The University of Guelph, also known as U of G, is a comprehensive public research university in Guelph, Ontario, Canada. It was established in 1964 after the amalgamation of Ontario Agricultural College, the Macdonald Institute, and the Ontario Veterinary College, and has since grown to an institution of more than 21,000 students and academic staff. Wikipedia.
Schmidt M.L.,University of Guelph |
Davis J.H.,University of Guelph
Langmuir | Year: 2017
Model membranes composed of two types of long chain phospholipids, one unsaturated and one saturated, along with cholesterol can exhibit two coexisting fluid phases (liquid disordered (ld) and liquid ordered (lo)) at various temperatures and compositions. Here we used 1D and 2D 2H NMR to compare the behavior of multilamellar dispersions, magnetically oriented bicelles, and mechanically aligned bilayers on glass plates, all of which contain the same proportions of dipalmitoleoylphosphatidylcholine (DPoPC), dimyristoylphosphatidylcholine (DMPC), and cholesterol. We found that multilamellar dispersions and bilayers aligned on glass plates behave very similarly. These samples were close to a critical composition and exhibit exchange of the lipids between the two fluid phases at temperatures near the ld to ld-lo phase boundary. On the other hand, when a short chain lipid is added to the ternary long chain lipid/cholesterol mixture to form bicelles, the phase behavior is changed significantly and the lo phase occurs at a higher than expected temperature. In addition, there was no evidence of exchange of lipids between the ld and lo phases or critical fluctuations at the temperature where the bulk of the sample enters the two-phase region for these bicelles. It appears that the addition of the short chain lipid results in these samples no longer being near a critical composition. © 2017 American Chemical Society.
Siddique A.R.M.,University of Guelph |
Mahmud S.,University of Guelph |
Heyst B.V.,University of Guelph
Renewable and Sustainable Energy Reviews | Year: 2017
Thermoelectric generators are solid state energy harvesters which can convert thermal energy into electrical energy in a reliable and renewable manner. Over the last decade, the human body has been considered as a good source of heat to harvest electrical energy through wearable thermoelectric generators. It may become an alternative power generation technique compared to other conventional ones used for many wearable devices. The wearable thermoelectric generator has potential to generate sufficient energy for any wireless sensor nodes (typically power requirements
O'Connor J.J.M.,University of Guelph |
Barclay P.,University of Guelph
Evolution and Human Behavior | Year: 2017
Perceptions of trustworthiness are an important predictor of social outcomes, such as monetary exchanges, criminal sentencing, and the attainment of leadership roles. Higher testosterone levels predict both lower voice pitch and untrustworthy behavior, across economic and mating contexts. Here, we tested the influence of voice pitch on perceptions of trustworthiness across general, economic, and mating-related (mate poaching, infidelity) contexts. We found that the context of trust and the sex of the speaker both changed how voice pitch affected perceived trustworthiness. Listeners were more trusting of higher-pitched female voices in economic and mate poaching contexts, but trusted lower-pitched female voices more in general. Listeners were more trusting of higher-pitched male voices in economic and mating-related contexts, and also tended to perceive higher-pitched male voices as more trustworthy in general. Listeners' attributions of trustworthiness were generally unrelated to perceptions of attractiveness from similarly-pitched voices, indicating that trust-related attributions were independent of preferences for higher- or lower-pitched voices. Furthermore, perceptions of general trustworthiness were associated with perceptions of economic trust, but were not consistently associated with perceptions of mating-related trust. These findings provide evidence that voice pitch alone is sufficient to influence trust-related perceptions, and demonstrates that listeners use voice pitch as a cue to trustworthy behavior. © 2017 Elsevier Inc.
Wang X.,University of Guelph |
Lim L.-T.,University of Guelph
Food Chemistry | Year: 2017
Two CO2 formation pathways (chlorogenic acid (CGA) degradation and Maillard reaction) during coffee roasting were investigated. CGA is shown not a major contributor to CO2 formation, as heating of this compound under typical roasting conditions did not release a large quantity of CO2. However, heating of a CGA moiety, caffeic acid, resulted in high yield of CO2 (>98%), suggesting that CGA hydrolysis could be the rate limiting step for CO2 formation from CGA. A large amount of CO2 was detected from glycine-sucrose model system under coffee roasting conditions, implying the importance of Maillard reactions in CO2 formation. Further studies on the heating of various components isolated from green coffee beans showed that CO2 was generated from various green coffee components, including water insoluble proteins and polysaccharides. Around 50% of CO2 was formed from thermal reactions of lower molecular weight compounds that represent ∼25% by weight in green coffee. © 2016 Elsevier Ltd
Kreiner J.M.,University of Guelph |
Kron P.,University of Guelph |
Husband B.C.,University of Guelph
New Phytologist | Year: 2017
Fertilization involving unreduced (2n) gametes is considered the dominant mechanism of polyploid formation in angiosperms; however, our knowledge of the prevalence of and evolutionary mechanisms maintaining 2n gametes in natural populations is limited. We hypothesize that 2n gametes are deleterious consequences of meiotic errors maintained by mutation-selection balance and should increase in species with relaxed opportunities for selection on sexual processes (asexuality), reduced efficacy of selection (asexuality, selfing) and increased genome instability (high chromosome number). We used flow cytometry to estimate male 2n gamete production in 60 populations from 24 species of Brassicaceae. We quantified variation in 2n gamete production within and among species, and examined associations with life history, reproductive mode, genome size and chromosomal number while accounting for phylogeny. Most individuals produced < 2% 2n male gametes, whereas a small number had > 5% (up to 85%) production. Variation in 2n gamete production was significant among species and related to reproductive system; asexual species produced significantly more 2n gametes than mixed-mating and outcrossing species. Our results, unique in their multi-species perspective, are consistent with 2n gametes being deleterious but maintained when opportunities for selection are limited. Rare individuals with elevated 2n gamete production may be key contributors to polyploid formation. © 2017 New Phytologist Trust.
Preyde M.,University of Guelph
Journal of evidence-informed social work | Year: 2015
Through this article the authors present a case summary of the early phases of research conducted with an Integrated Knowledge Translation (iKT) approach utilizing four factors: research question, research approach, feasibility, and outcome. iKT refers to an approach for conducting research in which community partners, referred to as knowledge users, are engaged in the entire research process. In this collaborative approach, knowledge users and researchers jointly devise the entire research agenda beginning with the development of the research question(s), determination of a feasible research design and feasible methods, interpretation of the results, dissemination of the findings, and the translation of knowledge into practice or policy decisions. Engaging clinical or community partners in the research enterprise can enhance the utility of the research results and facilitate its uptake. This collaboration can be a complex arrangement and flexibility may be required to accommodate the various configurations that the collaboration can take. For example, the research question can be jointly determined and refined; however, one person must take the responsibility for orchestrating the project, including preparing the proposal and application to the Research Ethics Board. This collaborative effort also requires the simultaneous navigation of barriers and facilitators to the research enterprise. Navigating these elements becomes part of the conduct of research with the potential for rewarding results, including an enriched work experience for clinical partners and investigators. One practice implication is that iKT may be considered of great utility to service providers due to its field friendly nature.
Barclay P.,University of Guelph
Behavioral and Brain Sciences | Year: 2017
Physical attractiveness affects how one gets treated, but it is just a single component of one's overall "market value". One's treatment depends on other markers of market value, including social status, competence, warmth, and any other cues of one's ability or willingness to confer benefits on partners. To completely understand biased treatment, we must also incorporate these other factors. © Cambridge University Press 2017.
Cutler G.C.,Dalhousie University |
Scott-Dupree C.D.,University of Guelph
BioScience | Year: 2016
The issues of pesticides and the risks they pose to bees are hotly debated. A key area of contention is the "trustworthiness" of industry-funded studies that are used by regulatory agencies in their bee-pesticide risk assessments. Although some argue that research into pesticide safety should be funded only by government or independent bodies, systems such as good laboratory practice (GLP) help ensure the quality and transparency of regulatory data and reports, irrespective of the fact that industry may be the primary funding source. Here, we briefly describe some of our experiences in conducting GLP field studies examining the effects of neonicotinoid insecticides on honey bees, providing examples of the high degree of quality-assurance oversight, while reminding readers that so-called independent, peer-reviewed research has multiple potential shortcomings. © The Author(s) 2016. Published by Oxford University Press on behalf of the American Institute of Biological Sciences. All rights reserved.
Goodwin P.H.,University of Guelph |
Gao W.,University of Guelph
Plant Pathology | Year: 2017
The aim of this study was to determine if treatment of soil with a branched-chain alkane mixture known to induce resistance against Colletotrichum orbiculare also changes populations of bacterial endophytes from Nicotiana benthamiana. Eight culturable bacterial endophyte types matching six species of Bacillus and two species of Pseudomonas were found in roots, stem + petioles and/or leaves. Application of the branched-chain alkane mixture resulted in significantly higher endophyte populations compared to the water or emulsifier controls for the Pseudomonas sp. LW3, Bacillus simplex LW4 and Bacillus pumilis LW5 colony types in roots and the B. simplex LW4 colony type in stem + petioles. The Pseudomonas sp. LW3 and B. simplex LW4 colony types also had higher populations in pure cultures under in vitro conditions with the branched-chain alkane mixture compared to the controls. Inoculation with each of the eight colony types increased their population in the plant and induced resistance against C. orbiculare, with the most effective being Pseudomonas sp. LW3 and Pseudomonas alcaligenes SW1. Most of the endophytes could inhibit C. orbiculare growth in vitro, but the level of resistance in planta was not correlated to the ability of the colony type to inhibit C. orbiculare in culture. Thus, a branched-chain alkane mixture can selectively affect the biomass of a subset of bacterial endophytes, demonstrating that it is a novel in planta endophyte growth promoter. © 2017 British Society for Plant Pathology.
Prosser S.W.J.,University of Guelph |
Hebert P.D.N.,University of Guelph
Food Chemistry | Year: 2017
Honey is generated by various bee species from diverse plants, and because the value of different types of honey varies more than 100-fold, it is a target for fraud. This paper describes a protocol that employs DNA metabarcoding of three gene regions (ITS2, rbcLa, and COI) to provide an inexpensive tool to simultaneously deliver information on the botanical and entomological origins of honey. This method was used to examine seven varieties of honey: light, medium, dark, blended, pasteurized, creamed, and meliponine. Plant and insect sources were identified in five samples, but only the botanical or insect source could be identified in the other two. Two samples were found to be misrepresented. Although this method was generally successful in determining both plant and insect sources, honeys rich in polyphenolic compounds or subject to crystallization were recalcitrant to analysis, so further research is required to combat honey adulteration and mislabeling. © 2016
Ivy C.M.,University of Guelph |
Robertson C.E.,University of Guelph |
Bernier N.J.,University of Guelph
Proceedings of the Royal Society B: Biological Sciences | Year: 2017
Eutrophication and climate change are increasing the incidence of severe hypoxia in fish nursery habitats, yet the programming effects of hypoxia on stress responsiveness in later life are poorly understood. In this study, to investigate whether early hypoxia alters the developmental trajectory of the stress response, zebrafish embryos were exposed to 4 h of anoxia at 36 h post-fertilization and reared to adults when the responses to secondary stressors were assessed. While embryonic anoxia did not affect basal cortisol levels or the cortisol response to hypoxia in later life, it had a marked effect on the responses to a social stressor. In dyadic social interactions, adults derived from embryonic anoxia initiated more chases, bit more often, entered fewer freezes and had lower cortisol levels. Adults derived from embryonic anoxia also performed more bites towards their mirror image, had lower gonadal aromatase gene expression and had higher testosterone levels. We conclude that acute embryonic anoxia has long-lasting consequences for the hormonal and behavioural responses to social interactions in zebrafish. Specifically, we demonstrate that acute embryonic anoxia favours the development of a dominant and aggressive phenotype, and that a disruption in sex steroid production may contribute to the programming effects of environmental hypoxia. © 2017 The Author(s) Published by the Royal Society. All rights reserved.
Matta R.,University of Guelph |
Tiessen A.N.,University of Guelph |
Choleris E.,University of Guelph
Neuropsychopharmacology | Year: 2017
The neurobiological mechanisms underlying social learning (ie, in which an animal’s learning is influenced by another) are slowly being unraveled. Previous work with systemic treatments shows that dopamine (DA) D1-type receptors mediate social learning in the social transmission of food preferences (STFP) in mice. This study examines the involvement of one brain region underlying this effect. The ventral tegmental area has dopaminergic projections to many limbic structures, including the hippocampus—a site important for social learning in the STFP in rodents. In this study, adult male and female CD-1 mice received a dorsal hippocampal microinfusion of the D1-like receptor antagonist SCH23390 at 1, 2, 4, or 6 μg/μl 15 min before a 30 min social interaction with a same-sex conspecific, in which mice had the opportunity to learn a socially transmitted food preference. Results show that social learning was blocked in female mice microinfused with 6 μg/μl, and in males infused with 1, 4, or 6 μg/μl of SCH23390. This social learning impairment could not be explained by changes in total food intake, or olfactory discrimination. A detailed analysis of the social interactions also revealed that although SCH23390 did not affect oronasal investigation for either sex, drug treatments affected other social behaviors in a sex-specific manner; there was primarily a reduction in agonistic-related behaviors among males, and social investigatory-related behaviors among females. Thus, this study shows that dorsal hippocampal D1-type receptors mediate social learning and social behaviors in male and female mice.Neuropsychopharmacology advance online publication, 29 March 2017; doi:10.1038/npp.2017.43. © 2017 American College of Neuropsychopharmacology
Manderville R.A.,University of Guelph |
Wetmore S.D.,University of Lethbridge
Chemical research in toxicology | Year: 2017
The formation of DNA adducts by the attack of intermediates derived from toxic substances at C8 of 2'-deoxyguanosine (dG) is a common damaging event. Although the majority of studies on C8-dG adducts have focused on lesions containing a C8-N-C tether between the bulky moiety and the nucleobase, the formation of O-linked lesions with a similar tether topology and C-linked adducts involving direct C8-C connectivity have also been uncovered. Several studies have been done to try to better understand the structural impact and mutagenicity of O-linked and C-linked aryl C8-dG adducts, including lesions arising from unsubstituted and chloro-substituted phenols and the food mutagen ochratoxin A (OTA). Information about the structural preferences of the adducts in duplexes containing the NarI sequence has been gained from optical spectroscopy (UV-vis, CD, and fluorescence), 19F NMR spectroscopy, and computational chemistry (density functional theory calculations at the nucleobase, nucleoside, and nucleotide levels and molecular dynamics simulations of adducted duplexes). The replication of select adducts has also been investigated using primer-elongation assays, and model high-fidelity and Y-family polymerases. Although the (unsubstituted) O-linked phenoxy-dG adduct preferentially induces a single duplex conformation and is replicated as per natural dG, chloro substitution blocks DNA replication. In contrast, the unsubstituted C-linked phenyl-dG adduct induces mismatches, while the C-linked ortho- and para-phenoxy-dG lesions lead to conformational heterogeneity of adducted DNA indicative of strong mutagenic potential. Finally, the C-linked OTA-derived lesion exhibits the greatest conformational flexibility in duplexes, which provides structural explanations for observed outcomes in OTA-exposed cells. Overall, the variation in the conformational preferences of DNA containing O-linked and C-linked aryl-dG adducts highlights the fact that the type of C8 linkage, the presence and location of functional groups in the bulky moiety, the adduct ionization state, and the sequence context can have profound effects on the conformational outcomes of adducted DNA, which directly dictate the activity of the original toxin.
Wang F.,University of Guelph
Proceedings of the 32nd International Conference on Computers and Their Applications, CATA 2017 | Year: 2017
An intelligent tutoring system (ITS) can teach students in a one-To-one, interactive way. It may help students achieve their learning goals better than classroom lecturing. An ITS should be able to teach adaptively based on knowledge states of students. Uncertainty is a challenge in developing an ITS. In practical tutoring, student information available to a teacher may be incomplete and uncertain. The partially observable Markov decision process (POMDP) model provides useful tools for handling uncertainty. It enables an ITS to take optimal teaching actions even when uncertainty exists in tutoring processes. In this paper, we reported an experimental ITS developed on the POMDP model. We describe the definitions of states, actions, observations in the POMDP framework, and the techniques for dealing with exponential state space and POMDP solving, which are major barriers in building POMDP based ITSs for practical applications. keywords: Intelligent system, computer supported education, partially observable Markov decision process. © ISCA, CATA 2017.
Mariani S.,University of Salford |
Cawthorn D.-M.,University of Salford |
Hanner R.,University of Guelph
Conservation Letters | Year: 2017
Recently, Stawitz et al. collated existing primary literature on DNA identification of finfish products and conducted a series of analyses to explore the environmental and economic ripples of species substitution. While we agree that the assessment of the impacts of seafood mislabeling is paramount, we show that the main conclusion of the study, which hints at a positive ecological impact arising from misnaming traded finfish species, is not warranted by the data, and may inadvertently cause damage to public perceptions of seafood provision, sustainability, and marine resource management. © 2017 Wiley Periodicals, Inc.
Holloway G.P.,University of Guelph
Sports Medicine | Year: 2017
Since the seminal finding almost 50 years ago that exercise training increases mitochondrial content in skeletal muscle, a considerable amount of research has been dedicated to elucidate the mechanisms inducing mitochondrial biogenesis. The discovery of peroxisome proliferator-activated receptor γ co-activator 1α as a major regulator of exercise-induced gene transcription was instrumental in beginning to understand the signals regulating this process. However, almost two decades after its discovery, our understanding of the signals inducing mitochondrial biogenesis remain poorly defined, limiting our insights into possible novel training modalities in elite athletes that can increase the oxidative potential of muscle. In particular, the role of mitochondrial reactive oxygen species has received very little attention; however, several lifestyle interventions associated with an increase in mitochondrial reactive oxygen species coincide with the induction of mitochondrial biogenesis. Furthermore, the diminishing returns of exercise training are associated with reductions in exercise-induced, mitochondrial-derived reactive oxygen species. Therefore, research focused on altering redox signaling in elite athletes may prove to be effective at inducing mitochondrial biogenesis and augmenting training regimes. In the context of exercise performance, the biological effect of increasing mitochondrial content is an attenuated rise in free cytosolic adenosine diphosphate (ADP), and subsequently decreased carbohydrate flux at a given power output. Recent evidence has shown that mitochondrial ADP sensitivity is a regulated process influenced by nutritional interventions, acute exercise, and exercise training. This knowledge raises the potential to improve mitochondrial bioenergetics in the absence of changes in mitochondrial content. Elucidating the mechanisms influencing the acute regulation of mitochondrial ADP sensitivity could have performance benefits in athletes, especially as these individuals display high levels of mitochondria, and therefore are subjects in whom it is notoriously difficult to further induce mitochondrial adaptations. In addition to changes in ADP sensitivity, an increase in mitochondrial coupling would have a similar bioenergetic response, namely a reduction in free cytosolic ADP. While classically the stoichiometry of the electron transport chain has been considered rigid, recent evidence suggests that sodium nitrate can improve the efficiency of this process, creating the potential for dietary sources of nitrate (e.g., beetroot juice) to display similar improvements in exercise performance. The current review focuses on these processes, while also discussing the biological relevance in the context of exercise performance. © 2017, The Author(s).
Barclay P.,University of Guelph
Evolutionary Psychology | Year: 2017
Economists and biologists have both theorized that individuals can benefit from committing to courses of action because it forces others to concede a greater share of any surpluses, but little experimental work has tested the actual benefits of such a strategy and people's willingness to so "tie their hands." Participants played a Battle-of-the-Sexes (Experiment 1) or Hawk-Dove game (Experiment 2), where one member of each pair could not change his or her action once played (committed), whereas the other could change actions in response (uncommitted). Committed players were more likely to achieve their preferred outcomes. When bidding to select roles, most participants preferred to be committed rather than uncommitted, though they bid slightly less than the committed role was actually worth. These results provide empirical support for people's willingness to use commitment to their advantage and show that commitment devices (e.g., "irrational" emotions) can bring long-term benefits. © The Author(s) 2017.
Erland L.A.E.,University of Guelph |
Saxena P.K.,University of Guelph
Journal of Clinical Sleep Medicine | Year: 2017
Study Objectives: Melatonin is an important neurohormone, which mediates circadian rhythms and the sleep cycle. As such, it is a popular and readily available supplement for the treatment and prevention of sleep-related disorders including insomnia and jet lag. This study quantified melatonin in 30 commercial supplements, comprising different brands and forms and screened supplements for the presence of serotonin. Methods: A total of 31 supplements were analyzed by ultraperformance liquid chromatography with electrochemical detection for quantification of melatonin and serotonin. Presence of serotonin was confirmed through analysis by ultraperformance liquid chromatography with mass spectrometry detection. Results: Melatonin content was found to range from .83% to +478% of the labelled content. Additionally, lot-to-lot variable within a particular product varied by as much as 465%. This variability did not appear to be correlated with manufacturer or product type. Furthermore, serotonin (5-hydroxytryptamine), a related indoleamine and controlled substance used in the treatment of several neurological disorders, was identified in eight of the supplements at levels of 1 to 75 ìg. Conclusions: Melatonin content did not meet label within a 10% margin of the label claim in more than 71% of supplements and an additional 26% were found to contain serotonin. It is important that clinicians and patients have confidence in the quality of supplements used in the treatment of sleep disorders. To address this, manufacturers require increased controls to ensure melatonin supplements meet both their label claim, and also are free from contaminants, such as serotonin.
Kozyn A.,University of Guelph |
Lubitz W.D.,University of Guelph
Renewable Energy | Year: 2017
This paper presents a complete power loss model for an Archimedes screw used for power generation (ASG) including a non-dimensional model to predict power losses due to outlet submersion flooding. This model amends a prior idealized, frictionless ASG performance model to include power losses due to bearing friction, outlet exit effects, internal hydraulic friction and outlet submersion. This study presents data and a derived relationship for power losses due to outlet submergence and found that unmodified Manning's coefficients can be used to model internal fluid friction losses. Laboratory experiments on a scale-model ASG were conducted to determine variable relationships and validate power loss models. The performance of a 7 kW grid-connected ASG was measured and used to validate model predictions. The proposed ASG power loss model improves the prior frictionless power model significantly and was generally capable of predicting the power output of a real-world ASG. © 2017 Elsevier Ltd
Miotto P.M.,University of Guelph |
Steinberg G.R.,McMaster University |
Holloway G.P.,University of Guelph
Biochemical Journal | Year: 2017
The obligatory role of carnitine palmitoyltransferase-I (CPT-I) in mediating mitochondrial lipid transport is well established, a process attenuated by malonyl-CoA (M-CoA). However, the necessity of reducing M-CoA concentrations to promote lipid oxidation has recently been challenged, suggesting external regulation on CPT-I. Since previous work in hepatocytes suggests the involvement of the intermediate filament fraction of the cytoskeleton in regulating CPT-I, we investigated in skeletal muscle if CPT-I sensitivity for M-CoA inhibition could be regulated by the intermediate filaments, and whether AMP-activated protein kinase (AMPK) could be involved in this process. Chemical disruption (3,3′-iminodipropionitrile, IDPN) of the intermediate filaments did not alter mitochondrial respiration or sensitivity for numerous substrates ( palmitoyl-CoA, ADP, palmitoyl carnitine and pyruvate). In contrast, IDPN reduced CPT-I sensitivity for M-CoA inhibition in permeabilized muscle fibers, identifying M-CoA kinetics as a specific target for intermediate filament regulation. Importantly, exercise mimicked the effect of IDPN on M-CoA sensitivity, suggesting that intermediate filament disruption in vivo is physiologically important for CPT-I regulation. To ascertain a potential mechanism, since AMPK is activated during exercise, AMPK β1β2-KO mice were utilized in an attempt to ablate the observed exercise response. Unexpectedly, these mice displayed drastic attenuation in resting M-CoA sensitivity, such that exercise and IDPN could not further alter M-CoA sensitivity. These data suggest that AMPK is not required for the regulation of the intermediate filament interaction with CPT-I. Altogether, these data highlight that M-CoA sensitivity is important for regulating mitochondrial lipid transport. Moreover, M-CoA sensitivity appears to be regulated by intermediate filament interaction with CPT-I, a process that is important when metabolic homeostasis is challenged. © 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.
News Article | May 3, 2017
Neonicotinoid pesticides hinder wild queen bumblebee's reproductive success, according to a new University of Guelph study. The study is the first to link exposure to thiamethoxam -- one of the most commonly used neonicotinoid pesticides -- to fewer fully developed eggs in queens from four wild bumblebee species that forage in farmland. "Queen bees will only lay eggs when the eggs are fully developed," said Prof. Nigel Raine, holder of the Rebanks Family Chair in Pollinator Conservation. If queens need to use energy to clear pesticides from their system instead of investing in eggs, then fewer fully developed eggs will result, he said. "This will likely translate into slower egg-laying rates, which will then impede colony development and growth." Published in the journal Proceedings of the Royal Society B, the study was conducted by Raine, along with Mark Brown and Gemma Baron from Royal Holloway University of London. Neonicotinoids are one of a number of factors contributing to the decline of bees and are currently being phased out or restricted in several countries including Canada. The researchers examined the impacts of exposing queen bumblebees to thiamethoxam during the spring when they emerge from hibernation and are preparing to lay their first eggs and establish a colony. "Given the vital role spring queens have in maintaining bumblebee populations, we decided to focus on assessing the impacts at this stage in the life cycle," said Raine, a professor in the School of Environmental Sciences. "These spring queens represent the next generation of bumblebee colonies." Worker bees from those first eggs are needed to clean and guard the nest, find food and tend to the next batch of eggs. Without those workers, the colony will likely fail, said Raine. In this study, about 500 queen bees from four species were caught in early spring and for two weeks were fed syrup treated with pesticide doses similar to levels found in pollen and nectar in the wild. They were then observed for another two weeks before they were frozen, dissected and examined. The researchers found that across all four species the queen bees that were given higher doses of thiamethoxam had smaller, less-developed eggs than the queens not exposed to the pesticide. Raine suspects the metabolic costs associated with the detoxification required from pesticide exposure results in a reduced amount of nutrients available for other biological processes such as egg development. The researchers also found queen bees from two of the four species ate less nectar after being exposed to thiamethoxam. "If their feeding rates drop off, the queens go into a dormant state," said Raine. "They won't have enough energy to fly or to collect pollen to feed their larvae. They may not even have enough resources to lay eggs." The fact that queen feeding behavior was impacted by exposure to thiamethoxam in only two of the four bee species highlights the reality that sensitivity to pesticides differs among bee species, added Raine. "Most of the work to determine levels of toxic exposure to pesticide has used honeybees as a model pollinator. But our findings show that bee species vary in their level of sensitivity to pesticides, which is important information that should be factored into regulatory decisions on these chemicals."
News Article | April 24, 2017
As a newly-minted single father (of a handsome cat named Mizue), I've had to deal with all of the challenges that come along with raising a kitten. For example, wondering almost constantly: what in the fuck do you want from me? Seriously. What. Do. You. Want. My beautiful boy's saucer eyes glimmer as he looks up at me and a "come hither" meow liltingly falls from his lips—it's hella petting time, or so I think. But when I go in for the pet, ever so gently, he strikes me across the hand. Why have you done me so very dirty, my son? We need a little help communicating. So, I called Lauren Dawson, a postdoctoral researcher at Guelph University who's trying to figure out what a cat's facial expressions mean, and how humans and cats can get along. As it turns out, I'm not the only one who doesn't know what my cat's facial expressions mean—neither do scientists. "We're more or less starting from scratch, to put it bluntly," Dawson said over the phone. "Every cat owner will say that their cat has different expressions in different situations, but it's not a heavily researched area."Read More: Cats Are Actually Nice, Scientists Find Thankfully, Dawson and her colleagues at the University of Guelph just launched an experiment to lay the groundwork for understanding cat expressions. An online survey (which you can take here) shows participants a bunch of cats, faces isolated, and asks them to guess the cat's mood. The researchers don't have a baseline for feline facial expressions, so they're working backwards: every cat in the survey is either in an unambiguously positive or negative situation. "If we see that people are able to distinguish between facial expressions in positive and negative situations, then there's more evidence to suggest we should investigate further," Dawson said. But why are cats so understudied? They've been around forever, and they are beautiful and precious. Still, it seems like nobody's paying much attention. Another recent study from Oregon University looked at cats' preferences for socialization—and found that they prefer human interaction to food—simply because nobody had done it before, even though dogs had been similarly studied. "There's a lot more research for dogs," Dawson said. "I don't have a good reason for that, but research for cats is often under-funded, and at the end of the day if you don't have money to do a study, it doesn't get done." For the good of my relationship with my son, I'm glad that at least this one study is happening. Subscribe to Science Solved It , Motherboard's new show about the greatest mysteries that were solved by science.
News Article | April 20, 2017
TORONTO, ON--(Marketwired - April 20, 2017) - Canada's air quality has dramatically improved over the past four decades despite significant population and economic growth and increased energy usage, finds a new study released today by the Fraser Institute, an independent, non-partisan Canadian public policy think-tank. "Imposing additional regulations might only harm economic growth with little or no measurable public benefit given Canada's air quality standards are already among the strictest in the world," said Ross McKitrick, professor of economics at the University of Guelph, Fraser Institute senior fellow and co-author of Canada's Air Quality Since 1970: An Environmental Success Story. The study finds that levels of four major air pollutants -- ground-level ozone, sulphur dioxide, nitrogen dioxide and carbon monoxide -- have all fallen substantially. In fact, from 1975 to 2015, concentrations of sulfur dioxide fell 92.3 per cent, nitrogen dioxide levels dropped 74.4 per cent, and carbon monoxide levels fell 90.4 per cent. And ground-level ozone, a key contributor to smog, fell 27 per cent between 1979 and 2015. Moreover, in 1975, 54 per cent of monitoring stations across Canada recorded nitrogen dioxide readings above acceptable levels. In 2015, there were zero such readings. And since 1999, only one reading for carbon monoxide -- in New Brunswick in 2011 -- has been above acceptable levels. Levels of other pollutants including fine particulates are consistently below the most stringent target levels. During the same 40 years, the size of Canada's economy -- as measured by real GDP -- grew by a staggering 242 per cent and the population increased 68 per cent. Energy use has jumped 21 per cent since 1995, and even motor fuel consumption has risen 26 per cent since the 1980s -- all the while air quality has continued to improve. "Canadians should be proud of their environmental record, as air pollution that accompanied more than 100 years of industrialization has been reduced to extremely low levels and Canada has now achieved some of the strictest air quality targets in the world," McKitrick said. To arrange media interviews or for more information, please contact: Aanand Radia, Media Relations Consultant Fraser Institute (416) 363-6575 ext. 238 email@example.com Follow the Fraser Institute on Twitter | Become a fan on Facebook The Fraser Institute is an independent Canadian public policy research and educational organization with offices in Vancouver, Calgary, Toronto, and Montreal and ties to a global network of think-tanks in 87 countries. Its mission is to improve the quality of life for Canadians, their families and future generations by studying, measuring and broadly communicating the effects of government policies, entrepreneurship and choice on their well-being. To protect the Institute's independence, it does not accept grants from governments or contracts for research. Visit www.fraserinstitute.org
News Article | May 4, 2017
A Canadian judge has ruled it's not illegal to give a thirsty pig a drink of water on its way to slaughter, in a heated months-long court case.. Anita Krajnc, an animal activist from Toronto, was acquitted of the charges of criminal mischief after she dribbled some water through the slats of a transport truck full of pigs in the summer of 2015. She was facing fines of up to $5,000 and possible jail time, but the judge ruled that since the pigs were still slaughtered, her actions clearly didn't really disrupt anything. "Pigs are not persons, they are property," Justice David Harris said, in response to an argument the defense had presented. "But the simple answer is that Krajnc didn't interfere with the lawful enjoyment of the property." It may seem like a commonsense verdict—since when is giving an animal a drink of water a crime? But the trial served as paradigm for a contentious debate over animal welfare, property rights, and food security. Activists like Krajnc argued her actions were compassionate and should be applauded, not punished. Personal property defenders argue it's not up to her to interfere with a farmer's animals in any way, even if she's trying to help. And food security experts said these laws are in place to protect the food supply from contaminants, and that they're taken more seriously due to recent zoonotic disease outbreaks. Assistant Crown attorneys (Canada's version of district attorneys) argued that Krajnc's actions threatened the safety of the food supply, since the driver of the truck couldn't verify that she was only giving the pigs water. Eric Van Boekel, the farmer who owned the pigs in the truck, testified in court that any interference, no matter how well intentioned, puts his animals at risk of contamination, and could make them unfit for slaughter. Concerns about food-borne illnesses, or even terrorist attacks, have made biosecurity—the process that manages risks in the food system—much stricter in recent years, according to Keith Warriner, a food security expert and professor of food science at the University of Guelph, in Canada. Read more: A Canadian Court Might Jail Woman for Giving Pigs Water "The worst case scenario is that somebody could introduce drugs for whatever reason—when I say drugs, I don't mean LSD, I mean an unknown antibiotic, for example," Warriner told me. "I do believe [Krajnc] had the best intentions, I'm not suggesting at all that she was trying to harm the pigs. But in the broader picture, it is a biosecurity issue, because not everybody will have the best intentions." Warriner pointed to cases of people intentionally poisoning dogs with tainted dog treats and said that farmers, and truck drivers, are just trying to prevent any unknown variables from entering the food system. He also said that the benefit of a small amount of water given to one or two pigs may not be worth the risk. But Harris ruled that it was clear, at least in this case, Krajnc didn't do anything wrong and compared her actions to people who leave out water dishes for thirsty dogs. "How is this any different?" Harris asked the Crown lawyers. The trial attracting international attention, pitting animal welfare activists against farmers and champions of personal property rights. Hundreds of supporters attended the courthouse in Milton, a suburb of Toronto, on Thursday to hear the verdict and support Krajnc. Subscribe to Science Solved It , Motherboard's new show about the greatest mysteries that were solved by science.
News Article | May 3, 2017
The research was conducted by Dr Gemma Baron , Professor Mark Brown of Royal Holloway, University of London and Professor Nigel Raine, (now based at the University of Guelph). The study investigated the impact of exposure to field-realistic levels of a neonicotinoid insecticide (thiamethoxam) on the feeding behaviour and ovary development of four species of bumblebee queen. Lead author, Dr Baron said, "We consistently found that neonicotinoid exposure, at levels mimicking exposure that queens could experience in agricultural landscapes, resulted in reduced ovary development in queens of all four species we tested." She continued, "Impacts of neonicotinoid exposure on feeding behaviour were species-specific, with two out of four species eating less artificial nectar when exposed to the pesticide. These impacts are likely to reduce the success of bumblebee queens in the spring, with knock-on effects for bee populations later in the year" added Baron. As the first to examine the impacts of these chemicals across multiple bumblebee species, this study is an important contribution to understanding the potential costs of using this class of insecticides. Dr Baron explained, "Previous studies have focused on a single bumblebee species and examined impacts in workers and established colonies. Bumblebee populations rely on spring queens to succeed, and by looking at the impacts of thiamethoxam on multiple species of spring queens, we have gained a step-change in our understanding". Thiamethoxam is currently under an EU moratorium, along with two other neonicotinoids. "The EU, and other countries, is weighing the benefits of using neonicotinoids to protect crops, against real concerns about how such pesticides can cause unintended harm to pollinators and other beneficial insects." added Professor Raine. "This work on wild bumblebee queens adds significantly to the evidence base on which to make such important policy decisions". Professor Brown commented that. "Our work provides a major step forward in understanding the general and species-specific impacts of neonicotinoids on wild bees. Future studies across different species are likely to demonstrate further variation in the impact of neonicotinoids, and conducting such studies needs to be a priority for scientists and governments." Explore further: Exposure to pesticides results in smaller worker bees More information: Gemma L. Baron et al. General and species-specific impacts of a neonicotinoid insecticide on the ovary development and feeding of wild bumblebee queens, Proceedings of the Royal Society B: Biological Sciences (2017). DOI: 10.1098/rspb.2017.0123
News Article | April 18, 2017
Now, having shed new light on their ancestors, a team of researchers from the Biodiversity Institute of Ontario at University of Guelph, Agriculture and Agri-Food Canada and University of Vienna, published their findings in the open access journal Zoosystematics and Evolution. Together, Drs. Valentina Todisco, Vazrick Nazari and Paul Hebert arrived at the conclusion that the enigmatic genus (Calinaga) originated in southeast Tibet in the Eocene as a result of the immense geological and environmental impact caused by the collision between the Indian and Asian subcontinents. However, the diversification within the lineage was far from over at that point. In the following epochs, the butterflies had to adapt to major changes when Indochina drifted away, leading to the isolation of numerous populations; and then again, when the Pleistocene climatic changes took their own toll. To make their conclusions, the scientists studied 51 specimens collected from a wide range of localities spanning across India, South China, Laos, Vietnam, Myanmar and Thailand. For the first time for the genus, the authors conducted molecular data and combined it with an examination of both genitalia and wing patterns - distinct morphological characters in butterflies. While previous estimates had reported existence of anywhere between one and eleven species in the genus, the present study identified only four, while confirming how easy it is to mislabel samples based on earlier descriptions. However, the researchers note that they have not sampled specimens from all species listed throughout the years under the name of the genus, so they need additional data to confirm the actual number of valid Calinaga species. The authors are to enrich this preliminary study in the near future, analysing both a larger dataset and type specimens in collaboration with the Natural History Museum of London that holds the largest Calinaga collection. Despite being beautiful butterflies, the examined species belong to a genus whose name derives from the Hindu mythical reptilian creatures Nāga and a particular one of them - Kaliya, which is believed to live in Yamuna river, Uttar Pradesh, and is notorious for its poison. According to the Hindu myths, no sooner than Kaliya was confronted by the major deity Krishna, did it surrender. "It seems that the modern taxonomy of Calinaga is in need of a Krishna to conquer these superfluous names and cleanse its taxonomy albeit after careful examination of the types and sequencing of additional material," comment the authors. Explore further: A colorful yet little known snout moth genus from China with five new species More information: Valentina Todisco et al, Preliminary molecular phylogeny and biogeography of the monobasic subfamily Calinaginae (Lepidoptera, Nymphalidae), Zoosystematics and Evolution (2017). DOI: 10.3897/zse.93.10744
News Article | April 18, 2017
A group of rare Asian butterflies which have once inspired an association with Hindu mythological creatures have been quite a chaos for the experts. In fact, their systematics turned out so confusing that in order to decode their taxonomic placement, scientists had to dig up their roots some 43 million years back. Now, having shed new light on their ancestors, a team of researchers from the Biodiversity Institute of Ontario at University of Guelph, Agriculture and Agri-Food Canada and University of Vienna, published their findings in the open access journal Zoosystematics and Evolution. Together, Drs. Valentina Todisco, Vazrick Nazari and Paul Hebert arrived at the conclusion that the enigmatic genus (Calinaga) originated in southeast Tibet in the Eocene as a result of the immense geological and environmental impact caused by the collision between the Indian and Asian subcontinents. However, the diversification within the lineage was far from over at that point. In the following epochs, the butterflies had to adapt to major changes when Indochina drifted away, leading to the isolation of numerous populations; and then again, when the Pleistocene climatic changes took their own toll. To make their conclusions, the scientists studied 51 specimens collected from a wide range of localities spanning across India, South China, Laos, Vietnam, Myanmar and Thailand. For the first time for the genus, the authors conducted molecular data and combined it with an examination of both genitalia and wing patterns - distinct morphological characters in butterflies. While previous estimates had reported existence of anywhere between one and eleven species in the genus, the present study identified only four, while confirming how easy it is to mislabel samples based on earlier descriptions. However, the researchers note that they have not sampled specimens from all species listed throughout the years under the name of the genus, so they need additional data to confirm the actual number of valid Calinaga species. The authors are to enrich this preliminary study in the near future, analysing both a larger dataset and type specimens in collaboration with the Natural History Museum of London that holds the largest Calinaga collection. Despite being beautiful butterflies, the examined species belong to a genus whose name derives from the Hindu mythical reptilian creatures Nāga and a particular one of them - Kaliya, which is believed to live in Yamuna river, Uttar Pradesh, and is notorious for its poison. According to the Hindu myths, no sooner than Kaliya was confronted by the major deity Krishna, did it surrender. "It seems that the modern taxonomy of Calinaga is in need of a Krishna to conquer these superfluous names and cleanse its taxonomy albeit after careful examination of the types and sequencing of additional material," comment the authors. Todisco V, Nazari V, Hebert PDN (2017) Preliminary molecular phylogeny and biogeography of the monobasic subfamily Calinaginae (Lepidoptera, Nymphalidae). Zoosystematics and Evolution 93(2): 255-264. https:/
Wang S.,Peking University |
Ladizhansky V.,University of Guelph
Progress in Nuclear Magnetic Resonance Spectroscopy | Year: 2014
Membrane proteins mediate many critical functions in cells. Determining their three-dimensional structures in the native lipid environment has been one of the main objectives in structural biology. There are two major NMR methodologies that allow this objective to be accomplished. Oriented sample NMR, which can be applied to membrane proteins that are uniformly aligned in the magnetic field, has been successful in determining the backbone structures of a handful of membrane proteins. Owing to methodological and technological developments, Magic Angle Spinning (MAS) solid-state NMR (ssNMR) spectroscopy has emerged as another major technique for the complete characterization of the structure and dynamics of membrane proteins. First developed on peptides and small microcrystalline proteins, MAS ssNMR has recently been successfully applied to large membrane proteins. In this review we describe recent progress in MAS ssNMR methodologies, which are now available for studies of membrane protein structure determination, and outline a few examples, which highlight the broad capability of ssNMR spectroscopy. © 2014 Elsevier B.V. All rights reserved.
Nasser N.,University of Guelph |
Hassanein H.,Queen's University
IEEE Communications Surveys and Tutorials | Year: 2011
While the demand for wireless cellular services continues to increase, radio resources remain scarce. As a result, network operators have to competently manage these resources in order to increase the efficiency of their Wireless Cellular Networks (WCN) and meet the Quality of Service (QoS) of different users. A key component of Radio Resource Management (RRM) is congestion control. Congestion can severely degrade the performance of WCN and affect the satisfaction of the users and the obtained revenues. Several congestion control techniques have been proposed for WCN. These techniques, however, do not provide incentives to the users to use the wireless network rationally, and hence they cannot solve the problem of congestion. Recently, there has been some research on providing monetary incentives to the users through congestion pricing to use the wireless network rationally and efficiently. Congestion pricing is a promising solution that can help alleviate the problem of congestion and generate higher revenues for network operators. This paper surveys recent research work on congestion pricing in WCN. It also provides detailed discussions and comparisons of the surveyed work as well as open problems and possible future research directions in the area. © 2005 IEEE.
Bienzle D.,University of Guelph |
Vernau W.,University of California at Davis
Clinics in Laboratory Medicine | Year: 2011
Lymphoma in dogs is a heterogeneous cancer with highly variable prognosis. Many types of canine lymphoma have similar counterparts in the World Health Organization classification of human lymphoid tumors. The most common variant of canine lymphoma is diffuse large B-cell lymphoma, which, if treated with multiagent chemotherapy, has a survival time of approximately 12 months. T-cell lymphomas are more heterogeneous and high- and low-grade variants are common, which necessitates classification beyond B- versus T-cell lineage. © 2011 Elsevier Inc.
Anacker B.L.,University of California at Davis |
Klironomos J.N.,University of British Columbia |
Maherali H.,University of Guelph |
Reinhart K.O.,U.S. Department of Agriculture |
Strauss S.Y.,University of California at Davis
Ecology Letters | Year: 2014
We examined whether plant-soil feedback and plant-field abundance were phylogenetically conserved. For 57 co-occurring native and exotic plant species from an old field in Canada, we collected a data set on the effects of three soil biota treatments on plant growth: net whole-soil feedback (combined effects of mutualists and antagonists), feedback with arbuscular mycorrhizal fungi (AMF) collected from soils of conspecific plants, and feedback with Glomus etunicatum, a dominant mycorrhizal fungus. We found phylogenetic signal in both net whole-soil feedback and feedback with AMF of conspecifics; conservatism was especially strong among native plants but absent among exotics. The abundance of plants in the field was also conserved, a pattern underlain by shared plant responses to soil biota. We conclude that soil biota influence the abundance of close plant relatives in nature. © 2014 John Wiley & Sons Ltd/CNRS.
Wang S.,University of Guelph |
Munro R.A.,University of Guelph |
Kim S.Y.,Sogang University |
Jung K.-H.,Sogang University |
And 2 more authors.
Journal of the American Chemical Society | Year: 2012
Protein-protein interactions play critical roles in cellular function and oligomerization of membrane proteins is a commonly observed phenomenon. Determining the oligomerization state and defining the intermolecular interface in the bilayer is generally a difficult task. Here, we use site-specific spin labeling to demonstrate that relaxation enhancements induced by covalently attached paramagnetic tag can provide distance restraints defining the intermonomer interface in oligomers formed by a seven-helical transmembrane protein Anabaena Sensory Rhodopsin (ASR). We combine these measurements with visible CD spectroscopy and cross-linking experiments to demonstrate that ASR forms tight trimers in both detergents and lipids. © 2012 American Chemical Society.
Silva L.C.R.,University of Guelph |
Silva L.C.R.,University of California at Davis |
Anand M.,University of Guelph
Ecosystems | Year: 2011
Recent studies have shown that tropical and subtropical forests expanded during the late Holocene, but rates and mechanisms of expansion are still unknown. Here, we investigate how a forest-grassland mosaic changed over the past 10,000 years at the southernmost limit of the Brazilian Atlantic forest. We used soil organic matter carbon isotopes (δ13C and 14C) to quantify and date changes in vegetation, examining soil properties and leaf traits of tree species (nutrient content, δ13C, δ15N, and specific leaf area-SLA) to describe potential mechanisms of expansion. Our results show that after several millennia of stability, forests have been expanding over grasslands through continuous, but very slow, border dynamics and patch formation (<100 m since ~4,000 YBP). This process of expansion coincided with past changes in climate, but biotic feedback mechanisms also appear to be important for the long-term persistence and expansion of forests. Soil fertility and microbial biomass match current rather than past vegetation distribution, increasing progressively across the gradient: grasslands < isolated trees < forest patches < forests. Foliar δ15N values of trees that are able to colonize the grassland are consistently lower across this vegetation gradient, suggesting an increasingly greater reliance on symbiotic nutrient uptake from grasslands to forests. No significant relationships were found between soil and leaf nutrients, but SLA explained variation in leaf N, P, and K (positive relationships) and in leaf δ13C (negative relationship). These findings suggest that a tradeoff between tree growth and water use efficiency is an important regulator of forest-grassland dynamics in the study region. © 2011 Springer Science+Business Media, LLC.
Gellner G.,University of California at Davis |
McCann K.S.,University of Guelph
Nature Communications | Year: 2016
The growing realization of a looming biodiversity crisis has inspired considerable progress in the quest to link biodiversity, structure and ecosystem function. Here we construct a method that bridges low- and high-diversity approaches to food web theory by elucidating the connection between the stability of the basic building block of food webs and the mean stability properties of large random food web networks. Applying this theoretical framework to common food web models reveals two key findings. First, in almost all cases, high-diversity food web models yield a stability relationship between weak and strong interactions that are compatible in every way to simple low-diversity models. And second, the models that generate the recently discovered phenomena of being purely stabilized by increasing interaction strength correspond to the biologically implausible assumption of perfect interaction strength symmetry.
Schleuning M.,Biodiversity and Climate Research Center |
Frund J.,University of Guelph |
Garcia D.,University of Oviedo
Ecography | Year: 2015
Research linking biodiversity and ecosystem functioning (BEF) has been mostly centred on the influence of species richness on ecosystem functions in small-scale experiments with single trophic levels. In natural ecosystems, many ecosystem functions are mediated by interactions between plants and animals, such as pollination and seed dispersal by animals, for which BEF relationships are little understood. Largely disconnected from BEF research, network ecology has examined the structural diversity of complex ecological networks of interacting species. Here, we provide an overview of the most important concepts in BEF and ecological network research and exemplify their applicability to natural ecosystems with examples from pollination and seed-dispersal studies. In a synthesis, we connect the structural approaches of network analysis with the trait-based approaches of BEF research and propose a conceptual trait-based model for understanding BEF relationships of plant-animal interactions in natural ecosystems. The model describes the sequential processes that determine the BEF relationship, i.e. the responses of species to environmental filters, the matching of species in ecological networks and the functionality of species in terms of their quantitative and qualitative contributions to plant demography and ecosystem functioning. We illustrate this conceptual integration with examples from mutualistic interactions and highlight its value for predicting the consequences of biodiversity loss for multispecies interactions and ecosystem functions. We foresee that a better integration between BEF and network research will improve our mechanistic understanding of how biodiversity relates to the functioning of natural ecosystems. Our conceptual model is a step towards this integration between structural and functional biodiversity research. © 2014 The Authors.
Shi L.,University of Guelph |
Kawamura I.,Yokohama National University |
Jung K.-H.,Sogang University |
Brown L.S.,University of Guelph |
Ladizhansky V.,University of Guelph
Angewandte Chemie - International Edition | Year: 2011
Break on through: High-resolution multidimensional solid-state NMR spectroscopy was used to refine the molecular conformation of a seven-helical transmembrane photoreceptor in lipids (see picture, right). H/D exchange experiments (see picture, left; black spectrum: H2O, red spectrum: D2O) reveal the solvent-exposed surface of the protein, which is asymmetrically positioned in the bilayer. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Pinto S.M.,University of Guelph |
Pinto S.M.,University of Montana |
MacDougall A.S.,University of Guelph
American Naturalist | Year: 2010
Whether plant distributions are governed more by neutral-based distance effects or niche-based environmental responses remains elusive. A lack of habitat matching, where species distributions do not correspond to environmental variability, suggests neutrality but can also be explained by niche models through the interactions of dispersal limitation, spatial autocorrelation of the environment, species interactions, and spatial scale. We untangle these effects in a field study with multiscale statistical analyses. We demonstrate that despite significant niche-based environmental responses by a savanna plant, we still see weak habitat matching, with the mechanisms responsible differing by spatial scale. At the coarse scale (100-200 m), dispersal limitation restricted the occupation of optimal habitat. At the fine scale (<30 m), dispersal was not limiting, but a lack of autocorrelation of environmental variables prevented the aggregation of reproductively active plants in optimal microsites. Species associations were largely unimportant at all scales. Extending our analysis to the entire community revealed similar scale-dependent limitations of distance and the environment, indicating weak habitat matching for all species. This work supports predictions that environmental specializations do not necessarily produce deterministic distributions in plant communities. It also provides a mechanistic explanation for why co-occurring plant species can have largely undifferentiated distributions. © 2010 by The University of Chicago.
Van Elsas J.D.,University of Groningen |
Semenov A.V.,University of Groningen |
Costa R.,University of Algarve |
Trevors J.T.,University of Guelph
ISME Journal | Year: 2011
In this review, our current understanding of the species Escherichia coli and its persistence in the open environment is examined. E. coli consists of six different subgroups, which are separable by genomic analyses. Strains within each subgroup occupy various ecological niches, and can be broadly characterized by either commensalistic or different pathogenic behaviour. In relevant cases, genomic islands can be pinpointed that underpin the behaviour. Thus, genomic islands of, on the one hand, broad environmental significance, and, on the other hand, virulence, are highlighted in the context of E. coli survival in its niches. A focus is further placed on experimental studies on the survival of the different types of E. coli in soil, manure and water. Overall, the data suggest that E. coli can persist, for varying periods of time, in such terrestrial and aquatic habitats. In particular, the considerable persistence of the pathogenic E. coli O157:H7 is of importance, as its acid tolerance may be expected to confer a fitness asset in the more acidic environments. In this context, the extent to which E. coli interacts with its human/animal host and the organism's survivability in natural environments are compared. In addition, the effect of the diversity and community structure of the indigenous microbiota on the fate of invading E. coli populations in the open environment is discussed. Such a relationship is of importance to our knowledge of both public and environmental health. © 2011 International Society for Microbial Ecology All rights reserved.
Fieberg J.,Wildlife Biometrics Unit |
Borger L.,University of Guelph |
Borger L.,French National Institute for Agricultural Research
Journal of Mammalogy | Year: 2012
Statisticians frequently voice concern that their interactions with applied researchers start only after data have been collected. The same can be said for our experience with home-range studies. Too often, conversations about home range begin with questions concerning estimation methods, smoothing parameters, or the nature of autocorrelation. More productive efforts start by asking good (and interesting) research questions; once these questions are defined, it becomes possible to ask how various design and analysis strategies influence one's ability to answer these questions. With this process in mind, we address key sample-design and data-analysis issues related to the topic of home range. The impact of choosing a particular home-range estimator (e.g., minimum convex polygon, kernel density estimator, or local convex hull) will be question dependent, and for some problems other movement or use-based metrics (e.g., mean step lengths or time spent in particular areas) may be worthy of consideration. Thus, we argue the need for more question-driven and focused research and for clearly distinguishing the biological concept of an animal's home range from the statistical quantities one uses to investigate this concept. For comparative studies, it is important to standardize sampling regimes and estimation methods as much as possible, and to pay close attention to missing data issues. More attention should also be given to temporally changing space-use patterns, with biologically meaningful time periods (e.g., life-history stages) used to define sampling periods. Last, we argue the need for closer connections between theoretical and empirical researchers. Advances in ecological theory, and its application to natural resources management, will require carefully designed research studies to test theoretical predictions from more mechanistic modeling approaches. © 2012 American Society of Mammalogists.
Jain S.S.,University of Guelph |
Bird R.P.,University of Windsor
International Journal of Cancer | Year: 2010
Zucker obese rats are highly sensitive to colon cancer and possess a plethora of metabolic abnormalities including elevated levels of cytokine tumor necrosis factor-± (TNF-±). The main objective of this study was to determine if physiologically elevated TNF-± affects colonic tumor phenotype with regard to an altered TNF-± signaling pathway. Zucker obese (fa/fa, homozygous recessive for dysfunctional leptin receptors), Zucker lean (Fa/fa, Fa/Fa) and Sprague-Dawley (SD) rats were injected twice with azoxymethane (10 mg/kg) over 2 weeks. After 30 weeks, the animals were terminated and physiological and tumor parameters were assessed. Obese rats had notably higher body and organ weights as well as plasma TNF-±, insulin and leptin levels than lean or SD animals. A 100% tumor incidence and significantly higher tumor size, multiplicity and burden were found in obese rats compared to the lean group that had 47.8% tumor incidence. The SD group had the lowest tumor incidence (20.0%). Tumors from obese animals had higher protein levels of TNF-±, TNF-±-receptor-2 (TNFR2), nuclear transcription factor-°B (NF-°B) and I°B-kinase (IKK) compared to lean animals. In both obese and lean groups, expression levels of these proteins were higher in tumors than in surrounding, normal-appearing colonic mucosae. These findings support an important role for TNF-± signaling in tumorigenesis and demonstrate that tumors growing in an obese state had significantly different expression levels of TNFR2 and NF-°B, proteins known to play a critical role in growth and survival, than those growing in the lean state. It is concluded that the physiological state of the host intricately affects tumor phenotype. © 2010 UICC.
Hassan M.,University of Guelph |
Mohany A.,University of Ontario Institute of Technology
Journal of Pressure Vessel Technology, Transactions of the ASME | Year: 2013
Steam generators in nuclear power plants have experienced tube failures caused by flow-induced vibrations. Two excitation mechanisms are responsible for such failures; random turbulence excitation and fluidelastic instability. The random turbulence excitation mechanism results in long-term failures due to fretting-wear damage at the tube supports, while fluidelastic instability results in short-term failures due to excessive vibration of the tubes. Such failures may require shutdowns, which result in production losses, and pose potential threats to human safety and the environment. Therefore, it is imperative to predict the nonlinear tube response and the associated fretting-wear damage to tubes due to fluid excitation. In this paper, a numerical model is developed to predict the nonlinear dynamic response of a steam generator with multispan U-tubes and anti-vibration bar supports, and the associated fretting wear due to fluid excitation. Both the crossflow turbulence and fluidelastic instability forces are considered in this model. The finite element method is utilized to model the vibrations and impact dynamics. The tube bundle geometry is similar to the geometry used in CANDU steam generators. Eight sets of flat-bar supports are considered. Moreover, the effect of clearances between the tubes and their supports, and axial offset between the supports are investigated. The results are presented and comparisons are made for the parameters influencing the fretting-wear damage, such as contact ratio, impact forces, and normal work rate. It is clear that tubes in loose flat-bar supports have complex dynamics due to a combination of geometry, tube-to-support clearance, offset, and misalignment. However, the results of the numerical simulation along with the developed model provide new insight into the flow-induced vibration mechanism and fretting wear of multispan U-tubes that can be incorporated into future design guidelines for steam generators and large heat exchangers. © 2013 American Society of Mechanical Engineers.
Trevors J.T.,University of Guelph |
van Elsas J.D.,University of Groningen |
Bej A.K.,University of Alabama at Birmingham
Current Issues in Molecular Biology | Year: 2013
In this perspective, we discuss the cytoplasm in actively growing bacterial cells contrasted with viable but nonculturable (VBNC) cells. Actively growing bacterial cells contain a more molecularly crowded and organized cytoplasm, and are capable of completing their cell cycle resulting in cell division. In contrast, nutrient starving bacteria in the physiological VBNC state are struggling to survive, as essential nutrients are not available or limiting. The cytoplasm is not as molecularly crowded as gene expression is minimal (e.g., ribosome, transcript, tRNA and protein numbers are decreased), energy pools are depleted, cells may exhibit leakage, and DNA is not being replicated for cell division.
Silva L.C.R.,University of Guelph |
Silva L.C.R.,University of California at Davis |
Anand M.,University of Guelph
Global Ecology and Biogeography | Year: 2013
Aim: Rising atmospheric CO 2 and climate warming have induced changes in tree growth and intrinsic water-use efficiency (iWUE) world-wide, but the long-term impact of such changes on terrestrial productivity remains unknown. Based on a synthesis of the literature, here we investigate the net impact of recent atmospheric changes across forest biomes. Location: A range of sites covering major forest biomes. Methods: We use dendrochronological and isotopic records to provide an integrated analysis of changes in growth and iWUE, evaluating the impacts of atmospheric changes in tree growth. In our analysis, positive relationships between changes in growth and iWUE reflect CO 2 stimulation, while neutral effects yield inflections in growth curves (plotted against iWUE), and negative relationships indicate the prevalence of stressors. To estimate net effects (since 1960) and compare responses across biomes, we use a response contrast (RC) index, based on the ratio between cumulative changes in growth and iWUE. Results: In 37 recently published case studies changes in iWUE were consistently positive, increasing by between 10 and 60%, but shifts in growth varied widely within and among forest biomes. Positive RC values were observed in high latitudes (>40°N), while progressively lower (always negative) responses were observed toward lower latitudes. Growth rates declined between 15 and 55% in tropical forests. In subtropical sites growth declined by between 7 and 10%, while mixed responses occurred in other regions. Main conclusions: Over the past 50 years, tree growth decline has prevailed despite increasing atmospheric CO 2. The impact of atmospheric changes on forest productivity is latitude dependent (R 2=0.9, P<0.05), but our results suggest that, globally, CO 2 stimulation of mature trees will not counteract emissions. In most surveyed case studies warming-induced stress was evoked to explain growth decline, but other factors, such as nutrient limitation, could have overridden the potential benefits of rising CO 2 levels. © 2012 Blackwell Publishing Ltd.
Marshall S.A.,University of Guelph |
Gill B.D.,Canadian Food Inspection Agency
Canadian Entomologist | Year: 2014
The beetle-hunting wasp, Cerceris fumipennis Say (Hymenoptera: Crabronidae), native to eastern North America, provisions its subterranean nest almost exclusively with adult metallic wood-boring beetles (Coleoptera: Buprestidae), including the destructive emerald ash borer (Agrilus planipennis Fairmaire, EAB). This wasp provides a unique opportunity to survey indigenous and nonindigenous buprestid diversity. We discuss the accessibility, sustainability, and productivity of C. fumipennis with respect to its application as a buprestid surveying and monitoring tool. Copyright © Entomological Society of Canada 2013.
Jarungthammachote S.,Kasetsart University |
Dutta A.,University of Guelph
International Journal of Energy Research | Year: 2012
To achieve hydrogen-rich and low-tar producer gas, multi-stage air-blown and air-steam gasification processes were studied in this research. Results showed that the tar content from multi-stage air-blown and air-steam gasification were lower, compared to the average value of that from downdraft gasification. In the cases of air supplies of 80, 100lmin -1 and 100, 100lmin -1 with steam, hydrogen yields were increased by 40.71 and 41.62%, respectively, compared to that without steam. These were about 1.6 times of hydrogen flow rate of the base case (S/B = 0). However, it was found that too much steam added to the process was disadvantageous. The equilibrium model was also applied to predict the hydrogen production and the composition of producer gas obtained from the multi-stage air-blown and air-steam gasification processes. The predicted result showed a better match for the case of multi-stage air-blown gasification process. © 2010 John Wiley & Sons, Ltd.
News Article | September 22, 2016
As chief scientist for a voyage of the research vessel Endeavor, oceanographer Melissa Omand oversaw everything from the deployment of robotic submarines to crew-member bunk assignments. The November 2015 expedition 150 kilometers off Rhode Island’s coast was collecting data for Omand’s ongoing investigations of the fate of carbon dioxide soaked up by the ocean. But Omand, an assistant professor at the University of Rhode Island’s campus in Narragansett, wasn’t on the ship. Instead of riding the waves with her crew, she was working, sometimes 16-hour days, inside a dark room at the university’s Inner Space Center — staring at computer monitors in a sort of NASA mission control for oceanographers. When she submitted the trip proposal a year earlier, she hadn’t foreseen that she’d be eight months pregnant with her first child when the ship set sail. Still, missing the trip was unthinkable, she says. The Inner Space Center, she realized, offered a way to direct the mission from shore via satellite. After proposing the solution to her higher-ups, and a lot of meetings that followed, she got permission to be the first chief scientist to remotely lead an Endeavor cruise. “She doesn’t let many obstacles get in her way,” says Colleen Durkin, an oceanographer at Moss Landing Marine Laboratories in California, who participated in the cruise. “That’s one of the fun things about working with her. She’s willing to try new things.” Her commitment to her science and her drive to find creative solutions are helping Omand tackle a big problem in oceanography. For a decade, she has been studying the mechanisms — such as currents and the dining and dying of microorganisms — that move carbon and nutrients through the ocean. In a breakout paper, published last year in Science, she reported the discovery that eddies can pull carbon from phytoplankton deep into the ocean, a previously undescribed phenomenon. Studying the fate of that carbon isn’t just interesting, she says, it’s vital to predicting the fate of our climate. “The ocean has a huge capacity to absorb excess carbon dioxide in our atmosphere,” Omand says. But as the planet warms, atmosphere and ocean might interact differently. Scientists need all the information they can get to figure out how to adapt to those changing conditions and mitigate the effects of climate change. Omand, 36, first got her feet wet on the rivers and lakes surrounding her hometown of Toronto. In her teens, she worked as a canoe guide, exploring the region’s waterways. “That was absolutely the root of my interest in earth science and environmental issues,” she says. “I’m essentially doing the same thing now, just on a much bigger boat.” After starting off as a premed student at the University of Guelph in Canada, she was ultimately drawn to the university’s physics program. “I found it very satisfying that all these problems boiled down to a few underlying rules and equations,” she says. During her undergraduate studies, her focus was millions and millions of kilometers away from Earth’s oceans. She coded software used to help calibrate X-ray instruments on NASA’s Mars Exploration Rovers, which identified the makeup of Martian rocks. While considering areas of physics for her graduate studies, Omand received an email that altered her heading. Chris Garrett, a professor (now emeritus) at Canada’s University of Victoria, introduced her to physical oceanography. “He showed me demonstrations of what happens to dye in a rotating water tank,” she recalls. “I was hooked by that.” The churning of water appealed to Omand for the same reason the field of physics did: Whether in tanks or oceans, the water’s movements can be expressed by a set of specific equations, called the Navier-Stokes equations. Omand has applied these equations in much of her work. During a Ph.D. at the Scripps Institution of Oceanography in La Jolla, Calif., she and colleagues studied the origins of a red tide off California’s coast. The team found that the red tide, fertilized by a layer of nutrients, had been festering under the ocean surface for a week before being drawn upward. Omand and her colleagues used a Jet Ski modified with a GPS system and scientific instruments to collect data. Later, as a postdoctoral researcher at Woods Hole Oceanographic Institution in Massachusetts, she and mentor Amala Mahadevan investigated mechanisms to explain how nitrogen, an important nutrient for phytoplankton, moves around below the sunlit layer of the sea. During her time at Woods Hole, Omand also started tracking the journey of CO taken in by springtime algae blooms in the North Atlantic. When the phytoplankton in these colossal blooms, which can stretch hundreds of kilometers across, die or are digested by other marine life, particles containing organic carbon are released into the water. The heavier of these particles sink, quarantining the carbon from the atmosphere. About 30 percent of all CO emitted by human activities has ended up in the oceans, thanks in part to these sinking particles. Scientists had believed that smaller particles would remain near the surface. But with robotic submarines called gliders that cruised up and down the water column sensing light scattered by the particles, Omand and colleagues found a surprisingly large amount of small carbon particles. These particles were around 100 to 350 meters deep, in the ocean’s “twilight zone,” where phytoplankton rarely live. Omand combined measurements such as temperature and salinity from several gliders to explain how the particles got pulled so far down. By analyzing those measurements alongside computer simulations and satellite data — an innovative mix of sources that provided finer details and the bigger picture — she showed that the carbon-rich particles were carried down by spiraling ocean currents called eddies. Water escaping these bowl-shaped depressions can become sandwiched between deeper ocean layers, remaining trapped along with any particles even once an eddy subsides. The accompanying carbon drain cools the Earth, says Eric D’Asaro, an oceanographer at the University of Washington in Seattle who collaborated with Omand on the research. Though the finding doesn’t change the total amount of carbon known to be taken in, the study identifies a new mechanism that could account for as much as half of all carbon known to be pulled into the deep North Atlantic during spring. The mechanism could also play a role elsewhere in the world’s oceans, D’Asaro, Omand and colleagues reported in April 2015 in Science. “Her work sets the table for the next decade in terms of understanding the interaction between the turbulence of the ocean and how carbon is injected down to depth,” says David Siegel, an oceanographer from the University of California, Santa Barbara. “She’s going to be one of the new leaders of this field.” Now a mother — her daughter was born a few weeks after the cruise — and an assistant professor at the University of Rhode Island, Omand continues her creative problem-solving, often by calling on unexpected technology. On a research trip in June (she was on the ship this time), Omand used an iPhone in a waterproof case to automatically snap pictures every half hour of particles raining down from the ocean’s top layer. Scientists previously measured the rates of sinking particles with traps that provided no information about how the rates changed throughout the day. Omand got the idea to affix her old iPhone to the traps after being offered only $40 for the used phone. “There’s got to be something really amazing I can do with this,” she thought. Next spring, Omand will harness the same telepresence software she used for the 2015 Endeavor trip to virtually take undergraduate students on board. Omand’s ability to harness technology to solve tricky scientific challenges is a big reason why she can identify new truths about our oceans, says Mahadevan. “Every problem she touches,” Mahadevan says, “something beautiful comes out.”
News Article | February 15, 2017
DARIEN, IL - A new study suggests that the melatonin content of dietary supplements often varies widely from what is listed on the label. Results show that melatonin content did not meet within a 10-percent margin of the label claim in more than 71 percent of supplements, with the actual content ranging from 83 percent less to 478 percent more than the concentration declared on the label. The study also found that lot-to-lot variability within a particular product varied by as much as 465 percent. "We found that some products have much more melatonin than is indicated on the label," said study co-author Praveen K. Saxena, PhD, professor in the department of plant agriculture and the Gosling Research Institute for Plant Preservation at the University of Guelph in Ontario, Canada. "Our findings reveal that further research is needed to clearly establish the stability and appropriate storage conditions to ensure safety, efficacy, and quality of melatonin products." Study results are published in the Feb. 15 issue of the Journal of Clinical Sleep Medicine. Melatonin is a natural hormone that helps regulate the daily cycle of sleep and wakefulness, with melatonin production increasing at night and decreasing in the morning. It also is widely available as a dietary supplement. Data from the National Center for Health Statistics of the National Institutes of Health show that the use of melatonin supplements by adults in the U.S. more than doubled from 0.6 percent in 2007 to 1.3 percent in 2012, with an estimated 3.065 million adults reporting that they had taken melatonin during the past 30 days. Saxena and lead author Lauren A.E. Erland analyzed 31 supplements by ultraperformance liquid chromatography with electrochemical detection. All products were purchased from local grocery stores and pharmacies in Guelph, Ontario. Supplements spanned 16 different brands and included a representative sample of formulations, including liquids, capsules and chewable tablets. Further analysis with mass spectrometry also found serotonin, a much more strictly controlled substance, in 26 percent of the tested supplements. According to the authors, the presence of unlabeled but significant quantities of serotonin could lead to serious side effects. "Millions of people use melatonin for a variety of purposes, including as a sleep aid," said Erland. "It is important that clinicians and patients have confidence in the quality of supplements used in the treatment of sleep disorders." Clinical guidelines published by the American Academy of Sleep Medicine recommend strategically timed melatonin as a treatment option for some circadian rhythm sleep-wake disorders, including jet lag disorder and shift work disorder. However, a new clinical practice guideline published by the AASM in the February issue of the Journal of Clinical Sleep Medicine suggests that clinicians not use melatonin as a treatment for sleep onset or sleep maintenance insomnia because the overall evidence available was weakly against melatonin's efficacy. Because melatonin is classified as a dietary supplement, it is not subject to the same scrutiny as medications that are approved by the U.S. Food and Drug Administration. When comparing supplement labels, U.S. consumers should look for the "USP Verified" mark, which indicates that the formulation meets the requirements of the U.S. Pharmacopeial Convention. It is important to talk to a doctor before taking melatonin as a dietary supplement. Help for an ongoing sleep problem is available from more than 2,500 sleep centers that are accredited by the American Academy of Sleep Medicine. The study was supported by a grant through the National Sciences and Engineering Research Council (NSERC) of Canada. To request a copy of the study, "Melatonin natural health products and supplements: presence of serotonin and significant variability of melatonin content," or the commentary, "Poor quality control of over-the-counter melatonin: what they say is often not what you get," or to arrange an interview with the study author or an AASM spokesperson, please contact Communications Coordinator Lynn Celmer at 630-737-9700, ext. 9364, or firstname.lastname@example.org The monthly, peer-reviewed Journal of Clinical Sleep Medicine is the official publication of the American Academy of Sleep Medicine, a professional membership society that improves sleep health and promotes high quality, patient-centered care through advocacy, education, strategic research, and practice standards. The AASM encourages patients to talk to their doctor about sleep problems and visit http://www. for more information about sleep, including a searchable directory of AASM-accredited sleep centers.
News Article | December 6, 2016
People must be part of the equation in conservation projects. This will increase local support and the effectiveness of conservation. That's the main conclusion of a study published online Nov. 29 in the journal Biological Conservation. In it, an international group of scientists recognizes the need to consider humans' livelihoods, cultural traditions and dependence on natural resources when planning and carrying out conservation projects around the world. "We really need to think about people as we're creating conservation initiatives. Forgetting about humans in the conservation recipe is like forgetting yeast in a loaf of bread," said lead author Nathan Bennett, a researcher at the University of Washington, the University of British Columbia and Stanford University. As the Earth continues to lose species and natural resources, the common approach to conservation has been to emphasize natural science to solve ecological problems, leaving people's relationships to natural resources out of the discussion. Increasingly, natural scientists and social scientists are partnering to try to consider both the needs of nature and of stakeholders. But for lack of good precedent, funding and will, often conservation organizations and activities don't fully consider the human dimensions of conservation, the authors found. "When people are ignored and conservation measures are put in, we see opposition, conflict and often failure," Bennett said. "These problems require the best available evidence, and that includes having both natural and social scientists at the table." This paper follows dozens of studies that point out the need for humans to be considered in environmental management and conservation, but few have articulated the benefits of doing so and exactly how to do this, Bennett explained. This review paper is the first to bring together the entire storyline by listing the practical contributions the variety of social sciences can offer to improve conservation. "This paper helps us to move beyond statements about the need for this toward actually setting the agenda," Bennett said. Two years ago, Bennett convened an international working group to find ways to practically involve more social scientists from fields such as geography, history, anthropology and economics in conservation projects. This paper is one of several outcomes from that working group. Another paper published in July 2016 suggests that conservation organizations and funders should put more emphasis on social sciences and explains what an ideal "conservation team" could look like. This new study calls for action to ensure that we have learned the lessons from past failures and successes of ignoring or considering human dimensions in conservation. In Thailand, for example, officials set up a series of marine protected areas along the country's coastline to try to conserve threatened habitats, including coral reefs, mangroves and seagrass meadows. But they didn't consider the thousands of fishermen and women who live near or inside the marine protected areas and rely on fishing and harvesting for livelihoods and feeding their families. Fishing bans and unfair treatment have led to resentment and opposition. In one case, fishermen burned a ranger station in protest. To add to the divisiveness, big commercial boats still caught fish in these areas because the protection zones were not well enforced. A recent successful example was the creation of California's marine protected area network. Local fisheries and communities, along with scientists, fishery managers, government and industry, were all brought to the table and the outcome ultimately was supported by most groups involved, Bennett explained. Similarly, right now in British Columbia planning for marine protected areas is underway, and First Nations leaders are working alongside local and federal governments. Successful conservation projects happen when both natural and social scientists are working with government, nonprofits, resource managers and local communities to come up with solutions that benefit everyone. This can take more time and resources at the outset, but Bennett and his collaborators argue that social scientists are often in a position to help make this a more efficient process. "Ignoring the people who live in an area can be a costly mistake for conservation. This is one of those cases where an ounce of prevention can be worth more than a pound of cure," he said. "Specialists in the social sciences can develop more creative, robust and effective solutions to environmental problems that people are going to get behind." Patrick Christie, a UW professor in the School of Marine and Environmental Affairs, is a co-author on the paper. Other co-authors are from the University of British Columbia, Stanford University, the University of Guelph, the University of Saskatchewan, the American Museum of Natural History in New York, the University of Victoria, the University of Wyoming, the University of Waterloo, the International Union for Conservation of Nature in Switzerland, Oregon State University, Memorial University of Newfoundland, Cornell University, Slippery Rock University, Georgia State University and World Wildlife Fund International. This study and co-authors were funded by the Canadian Wildlife Federation, the Social Science and Humanities Research Council, the Liber Ero Foundation, Fulbright Canada, the Smith Fellowship Program, the National Science Foundation and a number of other organizations. See the paper for a complete list. For more information, contact Bennett at email@example.com or 360-820-0181.
News Article | March 2, 2017
Fiberstar, Inc. (http://www.FiberstarIngredients.com), a global market leader in clean label food ingredient solutions for the food and beverage industry announced the winners to the Citri-Fi 125 Student Innovation Contest. Citri-Fi 125, a natural, non-GMO citrus fiber is one of the most recent additions to the Citri-Fi portfolio. To find new uses for this natural citrus fiber, Fiberstar launched a global innovation contest targeting University students. Over 25 applicants, globally, submitted a proposal in how to use the Citri-Fi 125. “This is the first time a program like this has been created, so we are pleased with the interest from the applicants,” says Fiberstar, Inc. President and CEO, John Haen. “We continue to support University food science programs by offering students opportunities to create food ingredient solutions for the real world.” A panel of judges ranked the students’ applications based on originality of concept, justification/market need, ingredient commercial feasibility, technical feasibility and quality of their report. A total of $25,000 was awarded amongst the six winning proposals. The following winning teams and applications are: 1st Place: Citrus Fiber as an Effective Fat Blocker in Fried Seafood: Oregon State University Seafood Research and Education Center, U.S. (Dr. Jae Park, Kaitlin Junes and Angela Hunt). Citri-Fi 125 used in a coating formulation to reduce oil pick-up not only provides potential cost savings to processors due to reduced oil usage, but this also provides manufacturers opportunities to reduce fat and calories. The study also showed yield improvement due to increased pick-up and reduced cooking losses. 2nd Place: Reduced Fat Instant Laksa Paste: Surya University, Indonesia (Sylviana, Meutia Wafa' Khairunnisa Hakim, Amelia Adinda and Bryan Raharja). Citri-Fi 125 is used to reduce the amount of coconut milk used in Laksa paste to provide potential cost savings and fat reduction. Citri-Fi 125 provides emulsification stabilization and improved mouthfeel to simulate the texture of the full-fat version. This may be applicable to other coconut milks pastes, spreads, beverages and soups found not only in Asia, but also in other parts of the world due to the growing use of coconut. 3rd Place: Citri-Crunch Healthy Savory Extruded Pork Snack: Washington State University, U.S. (Ryan Kowalski, Bon-Jae Gu, Maria Dian Pratiwi Masli, Siyuan Wang and Hongchao Zhang). Citri-Fi 125 helped reduce the oil uptake and improved the flavor by enhancing the umami flavor of monosodium glutamate when reducing the sodium. This not only aligns with the market’s need for healthier snacks, but also offers snack manufacturers cost savings opportunities in less oil usage. 4th Place: Chicken Sausage with Reduced Oil & Improved Sensory: University of Peradeniya, Sri Lanka (Miss A.M. Aruni Shanika, Dr. Himali Samaraweera, Nirupa Edirisinghe, Hashinee Medika Ariyasena and Nuwan Jayawardena). Citri-Fi 125 provided emulsification stabilization and texturizing to help reduce the oil by at least 30% while maintaining a full-fat mouthfeel. This provides cost savings and health benefits due to the fat/caloric reduction. 5th Place: Calcium Fortification to Increase Viscosity and Enhance Gelling Properties: University of Guelph, Canada (Lisa Indris). Incorporating calcium with Citri-Fi 125 in liquid food formats improves the viscosity and provides improved stabilization. This enhanced feature opens doors in the natural dairy category where stabilization and mouthfeel are desired and needed. 6th Place: Natural Color Stabilizer in Berry Yammee Topping: Cornell University, U.S. (Fiona Harnischfeger, Sofía Lara, Victoria Chen, Katrina Cariño, Ana Chang, Sierra Jamir and Shiyu Cai). Citri-Fi 125 stabilizes natural colors during shelf-life to prevent phase separation and color bleeding. This benefit is crucial for consumer acceptance when using vibrant natural colors to indicate freshness. Fiberstar also offers other citrus fiber solutions via 100 series line which contains different fiber content than the 125 series, the 200 series which is citrus fiber and guar gum and the 300 series which is the citrus fiber and xanthan gum. The Citri-Fi citrus fiber product lines provide food manufacturers clean label texturizing solutions for various food products including bakery, beverages, dressings, meats, sauces and dairy. “We are excited to enhance our formulating tool box by promoting Citri-Fi 125 citrus fiber. Our team will continue working closely with our Customers to provide superior technical service support, quality product and new ideas especially those generated from the most recent innovation contest. And we look forward to connecting with Universities and students in the future to continue the collaboration.” For more information about the Innovation Contest applications, please contact Dr. Brock Lundberg at (651) 271-0328
LOWINPUTBREEDS - Development of integrated livestock breeding and management strategies to improve animal health, product quality and performance in European organic and low input milk, meat and egg production.
Agency: European Commission | Branch: FP7 | Program: CP-IP | Phase: KBBE-2007-1-3-07 | Award Amount: 8.94M | Year: 2009
The proposed integrating project LOWINPUTBREEDS aims to develop integrated LIVESTOCK BREEDING and MANAGEMENT strategies to improve ANIMAL HEALTH, product QUALITY and PERFORMANCE in European organic and low input milk, meat and egg production through research, dissemination and training activities. The consortium includes 11 academic centres of excellence and 6 genetics/breeding companies (4 SMEs) in 11 European, 2 ICPC and 2 industrialised third countries. The proposed project has 4 main Science and Technology OBJECTIVES: 1. To DEVELOP and evaluate INNOVATIVE BREEDING CONCEPTS, including (a) genome wide and (b) marker assisted selection, and (c) cross-, (d) flower- and (e) farmer participatory breeding strategies, which will deliver genotypes with robustness and quality traits required under low input conditions. The project will focus on 5 LIVESTOCK PRODUCTION SYSTEMS (dairy cows, dairy and meat sheep, pigs and laying hens) and design SPECIES-SPECIFIC BREEDING STRATEGIES for different macroclimatic regions in Europe. 2. To INTEGRATE the use of IMPROVED GENOTYPES with INNOVATIVE MANAGEMENT approaches including improved diets, feeding regimes and rearing systems. This will focus on issues (e.g. mastitis and parasite control, animal welfare problems) where breeding or management innovations alone are unlikely to provide satisfactory solutions. 3. To IDENTIFY potential ECONOMIC, ENVIRONMENTAL, GENETIC DIVERSITY and ETHICAL IMPACTS of project deliverables to ensure they conform to different societal priorities and consumer demands/expectations and are acceptable to producers. 4. To ESTABLISH an efficient TRAINING and DISSEMINATION programme aimed at rapid exploitation and application of project deliverables by the organic and low input livestock industry.
News Article | January 13, 2016
Marina Elliott never planned to apply her outdoor adventure skills to a career in research and exploration. But in October 2013, she saw an advertisement for a project in South Africa that called for cave explorers with archaeological experience who were also small enough to squeeze through a narrow passageway to excavate an underground chamber. She was startled by how perfectly qualified she was for the job. Already an avid rock climber and spelunker, Elliott was then finishing up a PhD in biological anthropology at Simon Fraser University in Vancouver, Canada. She had worked on excavations in remote places, including Siberia and northern Alaska. And she had the flexibility to drop everything to spend a month in Africa. She joined a team of five other women. One by one, they shimmied through a 12-metre-long chute with an 18-centimetre-wide pinch point, and they emerged with more than 1,500 fossils from 15 skeletons of a previously unknown species of ancient hominin called Homo naledi. The discovery helped her to land her current postdoc position in biological anthropology at the University of the Witwatersrand in Johannesburg, and she now leads a team of six cavers who continue to explore the region. Although Elliott's path required a dose of serendipity, her experience illustrates one of the many ways that scientists can combine a love for outdoor adventure with their career. Researchers who pursue extreme fieldwork say that the discoveries they make along the way provide a lifetime of adventure tales and shape their careers in positive ways. Combining an extracurricular passion for the outdoors with a high-stakes career, however, also brings complications, including the risk that nothing will go as planned. When preparing for fieldwork, 'adventure' researchers need to be particularly careful with logistics to ensure success — and their own survival. In addition, they often need to acquire specialized insurance and build a safety net of teammates and strategies to deal with inevitable obstacles. Even with the best-laid plans, disaster can still come in many forms — from violent weather and political strife to crippling injuries. Flexibility and quick thinking can be the difference between a productive trip and a waste of time — or worse. Stacy Kim, a marine ecologist at Moss Landing Marine Laboratories in California, regularly dives beneath the ice in Antarctica to study how human pollution affects life on the sea floor. On one trip, she spun out on a snowmobile and dislocated her shoulder. The weather was bad, and the remoteness of the location meant that it took several days for medical personnel to reach her by helicopter. For the rest of the trip, she was stuck on top of the ice, doing lab work instead of going underwater. Her teammates did the diving instead. “You try to make sure no single person is completely irreplaceable,” she says. When injuries and other obstacles occur, they can prematurely end expeditions — but stopping early is not always an option when a research agenda is involved. So, like Kim, many scientists who work in extreme locations try to factor in more time, gear and logistical support than they would for trips done purely for fun. Ecologist Catherine Cardelús of Colgate University in Hamilton, New York, does most of her field work in the tree canopies, a task that requires climbing up ropes while battling jungle heat and fending off biting insects. On each climb, she lugs a heavy pack filled with sample-collecting tags and bags, tape measures, notebooks, walkie-talkies, water, lunch and other supplies for days of work that can keep her in the trees for up to seven hours at a time. Cardelús says that her field season lasts two or three times longer than those of scientists whose research occurs on the ground. Some days of work are inevitably lost because of rain or wind, so she always makes sure to hit the trees immediately on good days. But because it is so exhausting, nobody is allowed to do work in the canopy for more than three days in a row. “You have to be incredibly flexible and forgiving,” says Cardelús. “You wake up in the morning and there's a shut-out rain, so you have to say, 'Oh well, let's punch in some data. Let's do lab work.' You constantly have to be open to the possibility that you can't do what you need to do.” It can help to consider unplanned diversions as opportunities, says Kyle Larson, a structural geologist at the University of British Columbia's Okanagan campus in Kelowna. In 2014 on a trip to Nepal, Larson and his team were stopped by snow at an elevation of 3,000 metres — only halfway to their planned destination. They collected what samples they could, but they were unable to gather data for a project of a student on the trek. She had to abandon the Nepal study and later did fieldwork in Saskatchewan instead, which led to some significant findings. “If you end up going to places you didn't expect to go,” Larson says, “you can discover things you didn't expect to discover.” Safety is also a major concern when working on the edge, and adventurous scientists recommend erring on the side of caution, both to protect team members and to sustain funding. After all, it can take extra effort to persuade a granting agency to give money to support a dangerous, lengthy or team-heavy expedition that may not go as intended. Early in his career, ecologist Douglas Larson (no relation to Kyle), now an emeritus professor at the University of Guelph, Canada, included climbing ropes in a purchase order so that he could rappel down cliffs in the Niagara Escarpment and study what turned out to be extremely ancient trees living there — a discovery so surprising that forest ecologists in the region disparaged the results before they saw samples. The university's director of safety and security told Larson that even one accident would shut his project down. From then on, he committed to extra precautions and redundancies in his equipment, so that even if someone had a heart attack, he or she could be pulled up. Instead of having two or three points of webbing attached to the anchors at a time, as do most recreational climbers, he and his group use four or five. Strong safety nets become essential in this line of work. Elliott's dig in South Africa had a medic on standby 24 hours a day. They notified several groups about their plans, including the South African military and a mining-rescue organization, so that they could get help quickly in case of a confined-space emergency. Many adventure-researchers buy specialized insurance that can provide rescue help in remote locations or that can cover accidents related to their work. But no insurance company can charter a helicopter-rescue mission to a place such as K2, the second-tallest mountain in the world, where geologist Mike Searle of the UK's University of Oxford has conducted research. He recommends building relationships with the locals in remote regions, and he always gets to know his porters. “If you're in trouble, those are the guys who are going to carry you down.” It also helps to be in shape, which is business as usual for many researchers who scale glaciers, climb mountains or dive to the ocean floor in frigid water. To prevent injury and to stay flexible and strong for caving, Elliott runs, hikes and takes exercise classes that combine ballet, Pilates and gymnastics. Kyle Larson lifts weights six days a week when he is not trekking. Kim freedives for fun, often down to 18 metres or so. And Searle, now aged 61, bikes to work every day. He also climbs, swims and surfs. “You can't climb mountains,” he says, “if you're a couch potato.” One summer day in 1998, Cardelús was dangling from a rope some 24 metres above ground, near the top of a tree in the Costa Rican jungle, when two howler monkeys began to make aggressive motions. Crouched about three metres away, they were shaking branches and baring their teeth with arms outstretched, ready to leap. “I thought, 'Oh my God, here they come',” she says. Then she heard “an ancestral guttural sound” — not from the two monkeys, but from her husband, who was working nearby. The monkeys scattered. Cardelús — who no longer climbs when monkeys are nearby — has experienced many such close calls that include run-ins with snakes, ants, bees and tarantulas (see 'Views from the other side'). “Each time you climb a tree for the first time, you have to be prepared to evacuate within 15 seconds,” she says. “It's always exciting getting into the canopy. And it's just as euphoric to get to the ground.” Wildlife is not the only source of heart-thumping adventure. One afternoon in the spring of 2011, Kyle Larson crested a mountain pass in Nepal to discover a steep, nearly sheer descent buried in waist-deep snow. The team could see neither the trail nor what they were stepping on. Last year, he arrived in the country's Makalu region on the heels of a busy storm season that had dumped metres of snow on the region. Piles of snow reached the rooftops, and trekking was treacherous. “Trying to walk down through that was scary,” he says. “There were lots of bruised knees and falls.” A certain level of psychological preparation is crucial for working in extreme environments that are, by nature, full of surprises. And that process often starts before the expedition begins. For Elliott, the idea of squeezing through an extremely tiny space presented the first mental obstacle. When Lee Berger, the palaeoanthropologist who recruited Elliott and her fellow cavers for the South Africa excavation, told them that they would need to fit through a small gap, “all of us ran around our houses measuring furniture and stuffing ourselves under it”, she says. She could wedge herself into the space just by expanding her lungs. As she applied, Elliott worried that she wasn't qualified enough or that she had screwed up the Skype interview. She continued to doubt herself even after arriving on site. On the first day of reconnaissance, she looked into the 12-metre-long vertical chute that the team was to descend. If someone were to get hurt, medics would have to tend to the injured person until she healed enough to get out on her own. “Psychologically, that was quite trying,” she says. “I remember looking down this shark's maw of rock, and you can't see where you're going because it's not a straight line, and thinking, 'Oh, gee, perhaps I've miscalculated my own skill set'.” Because academic courses typically do not cover the ins and outs of survival, Elliott relied instead on years of hands-on experience and prior training that had taught her to remain calm enough to deal with unexpected circumstances. Long before she took on the caving job in South Africa, she had worked as a field guide for an adventure-tour company in the Rocky Mountains and earned a certificate in wilderness first aid. Both equipped her with survival and decision-making skills. It is impossible to predict every emergency, she says. But one can learn to think quickly and clearly in any situation. “What you can prepare for,” she says, “is the mental stability to say, 'OK, what do we need to do next? Who needs to do it?” Elliott also advises young researchers to pursue all of their life passions, even if they seem completely unrelated. She started out studying veterinary medicine before earning a PhD in anthropology and landing the career-changing excavation post in South Africa. “My take-home message is, don't fuss if your career or life path appears to be a little bit circuitous,” she says. “You never really know where any given skill set or experience might lead you.”
News Article | August 22, 2016
TreeHugger has never had anything good to say about pod coffee or the pod people who sell it or drink it; it just always seemed like the world’s biggest, most ridiculous win of convenience over sustainability or economics, or flavour for that matter. We have in fact called them the ultimate design for unsustainability. But I was surprised to see a booth set up in little Dorset, Ontario by Muskoka Roastery, the local roaster in cottage country north of Toronto, displaying what they call a 100 percent compostable Keurig compatible coffee pod. Can this really exist? Actually, yes. The PurPod was developed by Club Coffee, a big 110 year old Canadian coffee distributor with help from the Bioproducts Discovery and Development Centre at the University of Guelph. The BDDC developed a bioplastic made from coffee chaff, the skin of the coffee bean that comes off during the roasting process. The filter mesh is also compostable and of course, so is the coffee. They had their pods certified by the Biodegradable Products Institute, a “not-for-profit association of individuals and groups from government, industry and academia is a leading authority on compostable products and has North America’s leading compostable label program.” They claim that after about 84 days “There is usually no visible trace of any part of the pod when it gets the air and moisture found in good large-scale aerobic composting processes.” This is very different from labelling something “biodegradable” which can take years, and certainly better than “recyclable” which when it comes to tiny complicated things like coffee pods, is ridiculous waste of time and energy to basically assuage the guilt of people buying the stuff. The love is not universal. It takes a lot more energy and material to make these pods, a lot more packaging, and they take up a lot more room when shipping. One Guelph environmentalist notes in the sadly now defunct Guelph Mercury, as we have, that “By and large, if you’re looking to be environmentally, socially and economically responsible, single-serve pods are not even part of the equation. You wouldn’t even consider using them.” The City of Toronto, home of Club Coffee, won’t accept them in their composting program. A company spokesperson told the CBC: “Toronto is saying they don't want to touch it," she said. "With so many of these pods out there, they're afraid of other pods that aren't biodegradable going into the green bin and contaminating it.” The City told the Globe and Mail: “It doesn’t make a difference if the company claims their products are compostable or biodegradable, largely because there is no consistency of production across the industry market.” But up here in Muskoka, a lot of people compost themselves, since you have to carry everything to the dump and they count every bag. The people who occupy the fancy second homes on the lakes in summer have the disposable income to spend a buck a cup on their coffee instead of the 26 cents it costs to make it from scratch with the same Muskoka roasted beans. They already own the damn Kuerig machines, so it is probably better that they feed them this. It still makes no sense, buying an expensive machine to make inferior coffee that costs four times as much per cup. But millions of people are doing it and at least it is getting a bit better. And Muskoka Roastery deserves credit for making the effort.
News Article | March 2, 2017
NDA Partners Chairman Carl Peck, MD, announced today that Greg Coulter, PhD, a pharmaceutical development executive with more than twenty years of experience in GLP, GMP, and GCP regulated drug development and manufacturing has joined the company as an Expert Consultant. He has extensive experience in drug substance characterization, drug product formulation, manufacturing scale-up, regulatory compliance, quality assurance, and CMC regulatory writing, and is a specialist in development of liquid and solid oral formulations, liquid and lyophilized injectable formulations, and clinical supplies manufacturing. During his professional career, Dr. Coulter has provided operational and regulatory CMC guidance for virtual, start-up, development stage, and commercial organizations. Dr. Coulter was formerly the Director of Formulations and Analytical Services at SNBL USA, Ltd.; Manager, cGMP Manufacturing at Cell Therapeutics, Inc.; Senior Process Chemist at Synthetech Inc.; and President of CTM Solutions, LLC. He is an experienced program manager and has planned and led the construction, equipping, hiring, and expansion of two GLP-compliant laboratories for a global CRO. “Dr. Coulter’s extensive experience in drug product formulation, process development, scale-up, and manufacturing, along with his expertise in clinical packaging, labeling, and distribution logistics for global clinical trials, make him an excellent addition to our Expert Consultant team,” said Dr. David Savello, Partner and Manager, Product Quality & CMC Practice. “We are pleased to welcome him to NDA Partners and introduce him to our clients.” Dr. Coulter earned his PhD in Biological Chemistry and MSc in Organic Chemistry from University of Guelph, Canada, and his BSc, Hon. in Biochemistry from Bishop’s University, Canada. About NDA Partners NDA Partners is a strategy consulting firm specializing in expert product development and regulatory advice to the medical products industry and associated service industries such as law firms, investment funds and government research agencies. The highly experienced Principals and Premier Experts of NDA Partners include three former FDA Center Directors; the former Chairman of the Medicines and Healthcare Products Regulatory Agency (MHRA) in the UK; an international team of more than 100 former pharmaceutical industry and regulatory agency senior executives; and an extensive roster of highly proficient experts in specialized areas including nonclinical development, toxicology, pharmacokinetics, CMC, medical device design control and quality systems, clinical development, regulatory submissions, and development program management. Services include product development and regulatory strategy, expert consulting, high-impact project teams, and virtual product development teams.
Cubitt T.S.,Complutense University of Madrid |
Chen J.,University of Guelph |
Chen J.,University of Waterloo |
Harrow A.W.,University of Washington
IEEE Transactions on Information Theory | Year: 2011
The zero-error classical capacity of a quantum channel is the asymptotic rate at which it can be used to send classical bits perfectly so that they can be decoded with zero probability of error. We show that there exist pairs of quantum channels, neither of which individually have any zero-error capacity whatsoever (even if arbitrarily many uses of the channels are available), but such that access to even a single copy of both channels allows classical information to be sent perfectly reliably. In other words, we prove that the zero-error classical capacity can be superactivated. This result is the first example of superactivation of a classical capacity of a quantum channel. © 2006 IEEE.
Hu J.,Michigan State University |
Baker A.,University of Leeds |
Bartel B.,Rice University |
Linka N.,Heinrich Heine University Düsseldorf |
And 3 more authors.
Plant Cell | Year: 2012
Peroxisomes are eukaryotic organelles that are highly dynamic both in morphology and metabolism. Plant peroxisomes are involved in numerous processes, including primary and secondary metabolism, development, and responses to abiotic and biotic stresses. Considerable progress has been made in the identification of factors involved in peroxisomal biogenesis, revealing mechanisms that are both shared with and diverged from non-plant systems. Furthermore, recent advances have begun to reveal an unexpectedly large plant peroxisomal proteome and have increased our understanding of metabolic pathways in peroxisomes. Coordination of the biosynthesis, import, biochemical activity, and degradation of peroxisomal proteins allows for highly dynamic responses of peroxisomal metabolism to meet the needs of a plant. Knowledge gained from plant peroxisomal research will be instrumental to fully understanding the organelle's dynamic behavior and defining peroxisomal metabolic networks, thus allowing the development of molecular strategies for rational engineering of plant metabolism, biomass production, stress tolerance, and pathogen defense. © 2012 American Society of Plant Biologists. All rights reserved.
Kasran M.,University of Guelph |
Cui S.W.,Guelph Food Research Center |
Goff H.D.,University of Guelph
Food Hydrocolloids | Year: 2013
Soy whey protein isolate (SWPI)-fenugreek gum (hydrolyzed and unhydrolyzed) conjugates were prepared by Maillard-type reaction in a controlled dry state condition (60 °C, 75% relative humidity for 3 days) to improve emulsification properties. Fenugreek gum was partially hydrolyzed using 0.05 M HCl at 90 °C for 10 min (HD10), 30 min (HD30) and 50 min (HD50) to examine if molecular weight had an effect on the emulsifying properties. The formation of SWPI-fenugreek gum conjugates was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Measurements of particle size distribution and average particle size have shown that conjugation of SWPI-fenugreek gum at 60 °C for 3 days was enough to produce relatively small droplet sizes in oil-in-water (o/w) emulsions. A ratio of 1:3 and 1:5 of SWPI:fenugreek gum was more effective in stabilizing emulsion compared to 1:1 ratio. Unhydrolyzed fenugreek gum conjugates exhibited better emulsifying properties compared to partially hydrolyzed fenugreek gum conjugates. The order of the conjugates in lowering the particle size of emulsions was as follows: SWPI-unhydrolzed fenugreek gum > SWPI-HD10 > SWPI-HD30 > SWPI-HD50. © 2012.
Sharma P.,University of Lethbridge |
Manderville R.A.,University of Guelph |
Wetmore S.D.,University of Lethbridge
Chemical Research in Toxicology | Year: 2013
The conformational flexibility of the C8-linked guanine adduct formed from attachment of ochratoxin A (OTA) was analyzed using a systematic computational approach and models ranging from the nucleobase to the adducted DNA helix. A focus was placed on the influence of the C8-modification of 2′- deoxyguanosine (dG) on the preferred relative arrangement of the nucleobase and the C8-substituent and, more importantly, the anti/syn conformational preference with respect to the glycosidic bond. Although OTA is twisted with respect to the base in the nucleobase model, addition of the deoxyribose sugar induces a further twist and restricts rotation about the C-C linkage due to close contacts between OTA and the sugar. The nucleoside model preferentially adpots a syn orientation (by 10-20 kJ mol-1 depending on the OTA conformation) due to the presence of an O5′-H···N3 interaction. However, when this hydrogen bond is eliminated, which better mimics the DNA environment, a small (<5 kJ mol-1) anti/syn energy difference is predicted. Inclusion of the 5′-monophosphate group leads to an up to 20 kJ mol-1 preference for the syn (nucleotide) conformation due to stabilizing base-phosphate interactions involving the amino group of guanine. Nevertheless, MD simulations and free energy analysis predict that both syn- and anti-conformations of OTB-dG are equally stable in helices when paired opposite cytosine. These results indicate that the adduct will likely adopt a syn conformation in an isolated nucleoside and nucleotide, while a mixture of syn and anti conformations will be observed in DNA duplexes. Since the syn conformation could stabilize base mismatches upon DNA replication or Z-DNA structures with varied biological outcomes, future computational and experimental work should elucidate the consequences of the conformational preference of this potentially harmful DNA lesion. © 2013 American Chemical Society.
Gherboudj I.,Université de Sherbrooke |
Magagi R.,Université de Sherbrooke |
Berg A.A.,University of Guelph |
Toth B.,Environment Canada
Remote Sensing of Environment | Year: 2011
The aim of this study was to estimate soil moisture from RADARSAT-2 Synthetic Aperture Radar (SAR) images acquired over agricultural fields. The adopted approach is based on the combination of semi-empirical backscattering models, four RADARSAT-2 images and coincident ground measurements (soil moisture, soil surface roughness and vegetation characteristics) obtained near Saskatoon, Saskatchewan, Canada during the summer of 2008. The depolarization ratio (χ v), the co-polarized correlation coefficient (ρ vvhh) and the ratio of the absolute value of cross polarization to crop height (Λ vh) derived from RADARSAT-2 data were analyzed with respect to changes in soil surface roughness, crop height, soil moisture and vegetation water content. This sensitivity analysis allowed us to develop empirical relationships for soil surface roughness, crop height and crop water content estimation regardless of crop type. The latter were then used to correct the semi-empirical Water-Cloud model for soil surface roughness and vegetation effects in order to retrieve soil moisture data. The soil moisture retrieved algorithm is evaluated over mature crop fields (wheat, pea, lentil, and canola) using ground measurements. Results show average relative errors of 19%, 10%, 25.5% and 32% respectively for the retrieval of crop height, soil surface roughness, crop water content and soil moisture. © 2010 Elsevier Inc.
Structural and energetic characterization of the major DNA adduct formed from the food mutagen ochratoxin A in the NarI hotspot sequence: Influence of adduct ionization on the conformational preferences and implications for the NER propensity
Sharma P.,University of Lethbridge |
Manderville R.A.,University of Guelph |
Wetmore S.D.,University of Lethbridge
Nucleic Acids Research | Year: 2014
The nephrotoxic food mutagen ochratoxin A (OTA) produces DNA adducts in rat kidneys, the major lesion being the C8-linked-2′-deoxyguanosine adduct (OTB-dG). Although research on other adducts stresses the importance of understanding the structure of the associated adducted DNA, site-specific incorporation of OTB-dG into DNA has yet to be attempted. The present work uses a robust computational approach to determine the conformational preferences of OTB-dG in three ionization states at three guanine positions in the NarI recognition sequence opposite cytosine. Representative adducted DNA helices were derived from over 2160 ns of simulation and ranked via free energies. For the first time, a close energetic separation between three distinct conformations is highlighted, which indicates OTA-adducted DNA likely adopts a mixture of conformations regardless of the sequence context. Nevertheless, the preferred conformation depends on the flanking bases and ionization state due to deviations in discrete local interactions at the lesion site. The structural characteristics of the lesion thus discerned have profound implications regarding its repair propensity and mutagenic outcomes, and support recent experiments suggesting the induction of double-strand breaks and deletion mutations upon OTA exposure. This combined structural and energetic characterization of the OTB-dG lesion in DNA will encourage future biochemical experiments on this potentially genotoxic lesion. © 2014 The Author(s).
Mahendran B.,University of Guelph |
Lishman L.,Environment Canada |
Liss S.N.,University of Guelph
Water Research | Year: 2012
Integrated fixed-film activated sludge systems (IFFAS) may achieve year-round nitrification or gain additional treatment capacity due to the presence of both flocs and biofilms, and the potential for multiple redox states and long solids retention time. Flocs and biofilms are distinctive microbial structures and characterization of the physicochemical and structural properties of these may provide insight into their respective roles in wastewater treatment and contaminant removal in IFFAS. Flocs and biofilms were examined from five different pilot media systems being evaluated for potential full scale implementation at a large municipal wastewater treatment plant. Flocs and biofilms within the same system possessed different surface characteristics; flocs were found to have a higher negative surface charge (-0.35 to -0.65 meq./g VSS) and are more hydrophobic (60%-75%) than biofilms (-0.05 to -0.07 meq/g VSS; 19-34%). The EPS content of flocs was significantly higher (range of 2.1-4.5 folds) than that of biofilms. In floc-derived extracellular polymeric substances (EPS), protein (PN) was clearly dominant; whereas in biofilm-derived EPS, PN and polysaccharide (PS) were present in approximately equal proportions. Biofilm EPS had a higher proportion of DNA when compared to flocs. Biofilm growth was preferential on the protected internal surfaces of the media. Colonization of the external surfaces of the media was evident by the presence of small microcolonies. The structural heterogeneity of the biofilms examined was supported by observed differences in biomass content, thickness and roughness of biofilm surface. The biofilm on the interior surface of media was found to be patchy with clusters of cells connected by an irregular arrangement of interconnecting EPS projections. Biofilm thickness ranged between 139 μm and 253 μm. The pattern of oxygen penetration is expected to be complex. Nitrifiers and denitrifiers were predominantly associated with the biofilms, and the latter were found to be dispersed throughout the film and arranged in micro-clusters, suggesting partial oxygen penetration. © 2012 Elsevier Ltd.
Bucklin A.,University of Connecticut |
Steinke D.,University of Guelph |
Blanco-Bercial L.,University of Connecticut
Annual Review of Marine Science | Year: 2011
More than 230,000 known species representing 31 metazoan phyla populate the world's oceans. Perhaps another 1,000,000 or more species remain to be discovered. There is reason for concern that species extinctions may outpace discovery, especially in diverse and endangered marine habitats such as coral reefs. DNA barcodes (i.e., short DNA sequences for species recognition and discrimination) are useful tools to accelerate species-level analysis of marine biodiversity and to facilitate conservation efforts. This review focuses on the usual barcode region for metazoans: a ∼648 base-pair region of the mitochondrial cytochrome c oxidase subunit I (COI) gene. Barcodes have also been used for population genetic and phylogeographic analysis, identification of prey in gut contents, detection of invasive species, forensics, and seafood safety. More controversially, barcodes have been used to delimit species boundaries, reveal cryptic species, and discover new species. Emerging frontiers are the use of barcodes for rapid and increasingly automated biodiversity assessment by high-throughput sequencing, including environmental barcoding and the use of barcodes to detect species for which formal identification or scientific naming may never be possible. Copyright © 2011 by Annual Reviews. All rights reserved.
Wilson A.D.M.,Carleton University |
McLaughlin R.L.,University of Guelph
Behavioral Ecology and Sociobiology | Year: 2010
Recently emerged brook charr (Salvelinus fontinalis) foraging in still-water pools along the sides of streams are either active, feeding on insects from the upper portion of the water column away from the stream bank, or sedentary, feeding on crustaceans emerging from the hyporheic zone near the stream bank. We tested whether the frequency of movement displayed by individual brook charr searching for prey in the field was related to the relative volume of the telencephalon, a brain region involved with movement and space use in fishes. Movement of individuals searching for prey was quantified in the field, individuals were captured and volumes of the telencephalon and of the olfactory bulbs, a brain region neighbouring the telencephalon but not implicated in space use, were measured. Individuals with larger telencephalon volumes moved more frequently on average while searching for prey in the field than did individuals with smaller telencephalon volumes. The frequency of movement was unrelated to differences in the volume of the olfactory bulbs, suggesting that the relationship between telencephalon volume and movement was not a consequence of differences in overall brain size. Demonstrating a correlation between foraging behaviour and brain morphology for brook charr exhibiting different foraging tactics suggests that diversification in brain structure and function could be important aspects of the foraging specialization believed to occur during early stages in the evolution and development of resource polymorphisms. © 2010 Springer-Verlag.
Burleigh T.J.,University of Guelph |
Schoenherr J.R.,Carleton University |
Lacroix G.L.,Carleton University
Computers in Human Behavior | Year: 2013
The uncanny valley theory (UVT) (Mori, 1970) proposes that when stimuli are defined by a near-perfect resemblance to humans they cause people to experience greater negative affect relative to when they have perfect human likeness (HL) or little to no HL. Empirical research to support this non-linear relationship between negative affect and HL has been inconclusive, however, and a satisfactory causal explanation has not yet emerged to explain existing findings. In two studies, we examined the relationship between HL and eeriness using digital human faces. First, we examined the relationship between HL and eeriness while controlling for extraneous variation in stimulus appearance. We created two HL continua by manipulating the facial proportions and polygon count of several digital human models. Second, we proposed and tested two causal hypotheses regarding the uncanny valley phenomenon that we refer to as category conflict and feature atypicality. We created two additional HL continua by manipulating the skin coloration and category membership of models. Across these continua we introduced an atypical feature. Our results suggest that HL is linearly related to emotional response, except under conditions where HL varies by category membership, suggesting that previous empirical findings might be explained as a category conflict. © 2012 Elsevier Ltd. All rights reserved.
Kim D.-G.,Landcare Research |
Vargas R.,CICESE |
Vargas R.,University of Delaware |
Bond-Lamberty B.,Pacific Northwest National Laboratory |
Turetsky M.R.,University of Guelph
Biogeosciences | Year: 2012
The rewetting of dry soils and the thawing of frozen soils are short-term, transitional phenomena in terms of hydrology and the thermodynamics of soil systems. The impact of these short-term phenomena on larger scale ecosystem fluxes is increasingly recognized, and a growing number of studies show that these events affect fluxes of soil gases such as carbon dioxide (CO 2), methane (CH4), nitrous oxide (N2O), ammonia (NH3) and nitric oxide (NO). Global climate models predict that future climatic change is likely to alter the frequency and intensity of drying-rewetting events and thawing of frozen soils. These future scenarios highlight the importance of understanding how rewetting and thawing will influence dynamics of these soil gases. This study summarizes findings using a new database containing 338 studies conducted from 1956 to 2011, and highlights open research questions. The database revealed conflicting results following rewetting and thawing in various terrestrial ecosystems and among soil gases, ranging from large increases in fluxes to non-significant changes. Studies reporting lower gas fluxes before rewetting tended to find higher post-rewetting fluxes for CO2, N2O and NO; in addition, increases in N2O flux following thawing were greater in warmer climate regions. We discuss possible mechanisms and controls that regulate flux responses, and recommend that a high temporal resolution of flux measurements is critical to capture rapid changes in gas fluxes after these soil perturbations. Finally, we propose that future studies should investigate the interactions between biological (i.e., microbial community and gas production) and physical (i.e., porosity, diffusivity, dissolution) changes in soil gas fluxes, apply techniques to capture rapid changes (i.e., automated measurements), and explore synergistic experimental and modelling approaches. © Author(s) 2012.
Agency: European Commission | Branch: FP7 | Program: CP-IP | Phase: KBBE-2007-3-1-03 | Award Amount: 11.21M | Year: 2008
Replacing fossil oil with renewable resources is perhaps the most urgent need and the most challenging task that human society faces today. Cracking fossil hydrocarbons and building the desired chemicals with advanced organic chemistry usually requires many times more energy than is contained in the final product. Thus, using plant material in the chemical industry does not only replace the fossil material contained in the final product but also save substantial energy in the processing. Of particular interest are seed oils which show a great variation in their composition between different plant species. Many of the oil qualities found in wild species would be very attractive for the chemical industry if they could be obtained at moderate costs in bulk quantities and with a secure supply. Genetic engineering of vegetable oil qualities in high yielding oil crops could in a relatively short time frame yield such products. This project aims at developing such added value oils in dedicated industrial oil crops mainly in form of various wax esters particularly suited for lubrication. This project brings together the most prominent scientists in plant lipid biotechnology in an unprecedented world-wide effort in order to produce added value oils in industrial oil crops within the time frame of four years as well as develop a tool box of genes und understanding of lipid cellular metabolism in order for rational designing of vast array of industrial oil qualities in oil crops. Since GM technologies that will be used in the project are met with great scepticism in Europe it is crucial that ideas, expectations and results are communicated to the public and that methods, ethics, risks and risk assessment are open for debate. The keywords of our communication strategies will be openness and an understanding of public concerns.
Agency: European Commission | Branch: H2020 | Program: RIA | Phase: COMPET-07-2014 | Award Amount: 4.55M | Year: 2015
Humanitys plans to further explore space require the development of bio-regenerative life support systems and in particular plant cultivation. Plants contribute to all major life support functions by producing food and oxygen, reducing carbon dioxide and recycling water and waste. Moreover, fresh crops also have a positive impact on crew psychological well-being. EDEN ISS aims to adapt, integrate and demonstrate plant cultivation technologies and operations procedures for safe food production on-board the International Space Station and for future human space exploration missions. The consortium will demonstrate operational capability of controlled environment agriculture technologies and procedures for safe food production in space. A mobile test facility will be built to provide realistic interfaces analogous to ISS. A one-year demonstration campaign at the Neumayer III Antarctic station will provide extensive testing and validation capability to increase the technology readiness level of key subsystems to 6. Further developing these technologies and operations procedures, including food quality and safety measurements, will also contribute to Europes interest in resource efficient crop cultivation, saving energy, countering the climate change and securing the supply of healthy and safe food. The interdisciplinary nature of EDEN ISS combines research in space engineering, horticulture, food science and microbiology. Leading space industries (Thales Alenia Space Italia, Airbus Defense and Space, Telespazio), research organizations (DLR, CNR, AWI), SMEs (Liquifer, Heliospectra, EnginSoft, Aero Sekur) and academia (Wageningen UR, University of Guelph, Limerick Institute of Technology) from six European countries (Germany, Ireland, Italy, Sweden, Austria, the Netherlands) and Canada join forces in a unique consortium to prepare the ground for further innovative research and development in human spaceflight and terrestrial applications.
News Article | February 21, 2017
A collaborative study describes a novel myoclonic epilepsy syndrome in dogs for the first time and discovers its genetic cause at DIRAS1 gene. The affected dogs developed myoclonic seizures at young age - on average 6 months old - and seizures occur typically at rest. In some of the dogs the seizures could be triggered by light. The canine myoclonic epilepsy resembles human juvenile myoclonic syndrome in many aspects and the study has therefore meaningful implications for epilepsy research across species, says Professor Hannes Lohi from the canine gene research group, University of Helsinki. Myoclonic epilepsies are one of the most common forms of epilepsy in human and the canine findings will not only help in diagnostics but also provide a novel entry point to understand the pathophysiology of the disease. The identified DIRAS1 gene may play a role in cholinergic transmission in the brain and provides a novel target for the development of epilepsy treatments. We found a novel epilepsy gene, DIRAS1, which has not been linked to any neurological diseases before. The gene is poorly characterized so far, but some studies suggest that it may play a role in cholinergic neurotransmission, which could be a highly relevant pathway for the myoclonic epilepsies, explains MSc Sarviaho, co-first author of the study. The genetic backgrounds of myoclonic epilepsies are not well known yet, and our study provides a new candidate gene, which helps to further characterize the underlying pathophysiology in future studies. This would be important for the development of new treatment scenarios, summarizes Professor Lohi, senior author of the study. The affected dogs continue to serve as preclinical models when new treatment options are sought in ongoing studies. The results have implications for both veterinary diagnostics and breeding programs. We screened over 600 Rhodesian Ridgebacks and about 1000 epileptic dogs in other breeds and found that the DIRAS1 defect was specific for juvenile myoclonic epilepsy in Rhodesian Ridgebacks so far, says MSc Sarviaho. With the help of the genetic test, veterinarians can diagnose this specific epilepsy in their canine patients while breeders will be able to identify carriers and revise the breeding plans to avoid future affected puppies. About 15% of the dogs in the breed carry the DIRAS1 mutation and dogs all over Europe and beyond are affected, says DVM Franziska Wieländer from LMU Munich. To characterize the clinical features, researchers utilized a novel wireless video-EEG recording method. This allows a real-time monitoring of the electrical events prior, during and after the seizure episode in unsedated dogs. All the wires from electrodes are attached to a small portable device on the dog's back that transmits the data straight to our computers. Thus, the dog is free to move around and we can record the EEG for long periods at one go, explains Professor Fiona James. She has been previously developing the method at the University of Guelph, Ontario, Canada. Video-EEG is a routine approach in the human epilepsy clinic but only piloted now for the dogs. The beauty of the method is that we can easily correlate the behavioral changes with the recorded electroencephalographs and compare them to human EEG results. Indeed, with this technique we were able to identify epilepsy at an early stage and prior to the development of generalized tonic-clonic seizures. Moreover, we found strikingly similar EEG patterns in dogs that have been described in human myoclonic epilepsy", describes Professor Andrea Fischer from LMU Munich. Video-EEG is a powerful new approach for veterinary epilepsy research compared to previous short, 20-minute interictal measurements under sedation and gives much more accurate results, says Wieländer. Careful clinical studies helped to establish proper study cohorts to identify the genetic cause. The study was published in Proceedings of the National Academy of Sciences of the USA (PNAS) on 20 February 2017.
News Article | December 22, 2016
Stop Hunger Now and the North Carolina State University Center for Student Leadership, Ethics and Public Service have named Jonathan Chin, a student at New York University, as the 2017 President William Jefferson Clinton Hunger Leadership Award recipient. The award will be presented at the Universities Fighting World Hunger Summit March 24-25 at Walsh University in North Canton, Ohio. Each year, students across the globe with a passion to end hunger are invited to apply for the award, named in honor of President Bill Clinton for his commitment to humanitarian causes, including the eradication of hunger. The award was first presented by President Clinton in 2009. Since then, the N.C. State Center for Student Leadership, Ethics & Public Service (CSLEPS) and Stop Hunger Now, a non-profit hunger relief organization, have presented the award to students from colleges or universities around the world. "For many people, college is really the last time that they're asked to think critically. If we can catch them at this crucial juncture and show them that being responsible for the people around them is powerful and fulfilling, then when they go out to become the leaders of tomorrow, they'll have that compassion with them," said Chin. When Chin discovered that many of his fellow students at New York University (NYU) did not have enough to eat, he used his coding skills to design a web platform connecting hungry students to those who had extra swipes available on their meal cards. His platform was the launching pad for his organization and subsequent mobile app, Share Meals. Chin’s next step was to conduct a study to find out how many students on campus were food insecure, as well as to determine how much food was being wasted in the form of expired meal card swipes. He found that 18.8% of students surveyed did not have enough to eat, while 523 students surveyed left $438,910.30 unused on their meal plans. Through collaboration with various university departments and students, Chin has dedicated himself to fighting hunger at NYU. In addition to the creation of Share Meals, he has played a lead role on a committee that is working to establish food pantries on campus. Chin has led cooking classes at NYU, teaching students how to create nutritious, affordable meals. He recently delivered a TEDx Talk at the University of Missouri, and his efforts have been featured in the New York Times. The Share Meals app was the winner of NYU’s 2016 Global Hackathon. Chin has advised students, faculty and staff from universities across the U.S. and the UK on how to implement programs to combat hunger on their own campuses. He hopes to expand Share Meals to other universities. Previous Clinton Award winners are: Balanding Mennah, Arizona State University (2016); Maria Rose Belding, American University (2015); Azeem Ahmed, Auburn University (2014); Brendan Rice, University of Alabama (2013); Ryan O’Donnell, NC State (2012); Gavin Armstrong, University of Guelph (2011); Sarah Nam, Harvard (2010); and John Coggin, NC State University (2009) About Stop Hunger Now Stop Hunger Now works to end hunger by providing food and life-changing aid to the world’s most vulnerable people, and by creating a global commitment to mobilize the necessary resources. Based in Raleigh, NC, Stop Hunger Now operates meal packaging programs in 20 U.S. cities and in six international locations. For information, visit http://www.stophungernow.org.
News Article | February 15, 2017
WEST WARWICK, R.I.--(BUSINESS WIRE)--LED innovation powerhouse Lighting Science today announced their entrée into the vertical farming space with the addition of an LED T8 grow lamp to their industry-leading VividGro product line. Engineered specifically for vertical farming facilities and grow chambers/facilities, the latest addition to the VividGro line packs high output, low heat radiation and the company’s patented grow spectrum into a sleek and flexible 4-foot linear design. “Providing lighting solutions for indoor food crop production was a logical extension of our VividGro product line,” said Pete Rumsey, Executive Vice President of Business Development for Lighting Science. “Unlike traditional high-pressure sodium (HPS) and fluorescent lighting, our new VividGro T8 emits very little radiated heat and can be used at close proximity to the plant canopy. It provides the same micromoles that our VividGro PAR 38 is known for, but with a thin profile that makes it a real problem-solver for vertical farming space constraints.” Since its introduction in 2015, VividGro has been providing growers with a low cost and energy-efficient alternative to high-pressure sodium (HPS) and fluorescent lighting. According to Rumsey, the new VividGro T8 uses about 50 percent less energy and lasts about ten times longer (50,000 hours) than comparable fluorescents, which typically have to be replaced every 8-10 months. VividGro’s proprietary spectrum technology also guarantees that plants receive the best levels of (photosynthetic photon flux) PPFD at each stage of growth. Academic research conducted by the University of Guelph showed that VividGro’s light spectrum accelerates the photosynthetic process, improves crop yield by up to 30 percent and increases the nutritional density of crops by 10-12 percent. As an added benefit, the VividGro T8’s flexible ballast bypass design provides indoor horticulturists with significant flexibility. The lamp can be hung individually, either vertically or horizontally, with single-ended connectors. For maximum customization, the VividGro T8 can also be installed in 1, 2, 3, 4 and 6 lamp, 4-foot troffers and hung in a direct wire troffer combo. Suitable for indoor commercial growers and do-it-yourself horticulturalists, the new VividGro T8 is highly adaptable to both urban and agricultural environments, including greenhouses of any scale. Driven by population growth, the decreasing availability of cultivatable land and demand for sustainably-grown local food, the vertical farming market is expected to reach an estimated $3.88 billion by 2020, up from $1.1 billion in 20151. Of that, lighting is expected to account for the largest share. Vertical farming is the practice of growing crops in vertically-stacked layers, often indoors where factors such as light, humidity and nutrients can be carefully controlled to maximize crop output and quality. Although a still relatively new concept in the United States, vertical farming has already taken off in countries such as Singapore, Japan and England, where large-scale facilities are seeing some success. According to The Vertical Garden author Dr. Dickson Despommier, “The vertical farm concept is about maximizing plant density to enable large numbers of people living in the built environment access to healthy, fresh vegetables year-round that are herbicide and pesticide-free.” Lighting Science continues to innovate with advanced technologies and spectrum control solutions to enhance plant growth at different stages. The company plans to further expand its VividGro product line with the launch its next generation VividGro 3 later this year. Lighting Science (OTCQB:LSCG) is a global leader in innovative LED lighting solutions that designs, manufactures and brings to market advanced, intelligent products for consumer and commercial applications. We are committed to using the science of light to improve the lives and health of people and our planet by inventing breakthrough, biologically-friendly LED lamps and lighting fixtures. Lighting Science is headquartered in West Warwick, RI, with research and development facilities in Cocoa Beach, Florida, and offices in China. Find out more about us and our products at www.lsgc.com and join us on Facebook, Twitter, LinkedIn and the Lighting Science Blog. 1 Vertical Farming Market by Functional Device (Lighting, Hydroponic Component, Climate Control, and Sensors), Growth Mechanism (Aeroponics, Hydroponics, and Others) and by Geography - Global Forecast to 2020, Market and Markets, January 2016
News Article | October 28, 2016
TORONTO, ON--(Marketwired - October 27, 2016) - Today NEXT Canada, a national non-profit organization committed to advancing Canadian entrepreneurship, announced the launch of NextAI, a program designed to bring together Canadian and international talent in the field of Artificial Intelligence (AI). By providing seed capital, expert advice, and sector-specific tools, program participants will be prepared to launch AI solutions in growing technology markets around the world. The program -- the first of its kind -- brings AI talent and entrepreneurs together with academic, corporate, and government partners to further position Canada as a leader in the global race to establish centres of excellence in the commercial application of AI. NextAI launches with partners in government and the private sector, including NEXT Canada's national partners EY, MasterCard, TD Group, and Osler, Hoskin & Harcourt. The program will provide access to technology platforms and organizational experts from a growing number of companies, including Google, Microsoft, and IBM. Teams will receive up to $200,000 in seed financing to develop their technology, and will also receive hands-on instruction from faculty at the University of Toronto, Georgetown University, University of Guelph, Massachusetts Institute of Technology, New York University, and Harvard University. "Canada has been at the forefront of artificial intelligence research for decades, and NEXT Canada has supported several AI-focused startups in past programs," said Graham Taylor, Academic Director at NextAI. "The launch of NextAI means we'll see the brightest minds from around the world creating industry-leading AI technology in Canada, cementing our place as a world leader in machine learning innovation." NextAI will run annually from February to September, recruiting up to 20 teams from graduate and undergraduate programs at top Canadian and international universities as well as industry professionals. The program will culminate in an AI Demo Day. NextAI applications are open today until January 5, 2017, and the program officially kicks off February 1, 2017. "Canada is the perfect place to shine a light on AI technology since we have the right combination of researchers, companies, and entrepreneurs who are already investing heavily in the space," said Sam Sebastian, Vice President and Country Director for Google Canada. "This is a win-win for anyone who believes in the potential of AI -- it means state-of-the-art AI technology will be developed in our backyard and deployed to solve commercially and socially important problems." This is NEXT Canada's third program devoted to helping young entrepreneurs succeed, and hundreds of entrepreneurs to date have participated in the Next 36 and Next Founders programs. NEXT Canada counts several AI and machine learning companies among its alumni, including Blue J Legal and Atomwise. The program was officially announced on stage at today's Rotman School of Management Machine Learning conference, which featured opening remarks from astronaut Chris Hadfield, a keynote by the Chair of President Obama's Council of Economic Advisors who described the White House's position on AI, presentations from some of the most influential pioneers in machine learning, and insights from investors focused on AI at top Silicon Valley-based VC firms including DFJ, DCVC, Andreessen Horowitz, and Kleiner Perkins. To learn more about NEXT Canada, visit www.nextcanada.com. NEXT Canada is an organization with a focus on increasing national prosperity through innovation and entrepreneurship. NEXT Canada was formerly known as The Next 36, a program founded in 2010 by a group of business leaders and academics. NEXT Canada's philosophy is to invest resources on exceptional individuals. With a strong belief in founder development, NEXT Canada uses a blend of mentorship, education and networking that inspires driven Canadians to disrupt industries and build globally relevant companies.
Bubenik G.A.,University of Guelph |
Konturek S.J.,Jagellonian University Medical College
Journal of Physiology and Pharmacology | Year: 2011
Human life span, with or without modern medicine is around 85-95 years. All living creatures have their inner clock that measures their daily (circadian) and their seasonal (circannual) time. These time changes are mediated by the alteration of levels of melatonin, an evolutionary ancient hormone, which is produced in many body tissues, including the pineal gland, retina and the gastrointestinal tract (GIT). Light is blocking the production of melatonin in the pineal gland, darkness is stimulating it. So, the diurnal changes of light intensity of melatonin, provide a daily clock and the seasonal changes provide a seasonal clock. Finally, the reduction of melatonin observed with aging, may indicate the presence of an age clock. Melatonin is a strong antioxidant (often it is called scavenger of free radicals), which protects the body from the effects of noxious compounds. Therefore it was hypothesized that the reduction of melatonin levels with age contributes to the aging process. So far, the only remedy to extend the life span was a 40% reduction in caloric intake, which prolonged the life in mice, rats, dogs and monkeys by 30-50%. A large group of people imitate these experiments performed on animals, but the results of these experiments will not be known for several decades. How is being hungry prolonging the life span? There is a connection between caloric reduction and melatonin levels in GIT. Several experiments indicate that fasting in animals substantially increased their production of GIT melatonin. Therefore, instead of being permanently hungry, a prolongation of human life could be achieved by a replacement melatonin therapy. A daily intake of melatonin before bed time might achieve the same effect as fasting e.g. an increase of body melatonin levels, which will protect the individual from the ravages of old age. That includes Parkinson's disease and Alzheimer's disease. There is a large group of people taking melatonin daily who believe that melatonin is the "fountain of youth". Those are the subjects which will one day provide an experimental evidence of the efficacy of melatonin.
Ernst O.P.,King's College |
Lodowski D.T.,Case Western Reserve University |
Elstner M.,Karlsruhe Institute of Technology |
Hegemann P.,Humboldt University of Berlin |
And 2 more authors.
Chemical Reviews | Year: 2014
Animal rhodopsins are employed in visual and nonvisual phototransduction, in the maintenance of the circadian clock and as photoisomerases. Animal rhodopsins are specialized G-protein-coupled receptors (GPCRs). Structures of animal and microbial rhodopsins differ largely and are drawn in opposite orientations with respect to the membrane. Light absorption initiates functions of both microbial and animal rhodopsins and the wavelength dependence of the absorption efficiency determines the colors of the proteins. The initial photochemical reaction in microbial and animal rhodopsins is known to be one of the fastest and most efficient chemical events in biology. Judging from the large number of new rhodopsin variants unearthed by genomic and metagenomic sequencing, new interesting functions of retinal proteins will continue to be discovered. This applies to both microbial and animal rhodopsins, and will lead to new breakthroughs in understanding microbial, invertebrate, and vertebrate physiology and evolution.
Ashigh J.,New Mexico State University |
Tardif F.J.,University of Guelph
Weed Science | Year: 2011
Many substitutions in the herbicide target enzyme acetohydroxyacid synthase (AHAS) confer whole-plant resistance and may reduce plant fitness. This study was done to determine the impact of different watering and temperature regimes on the germination, growth, and seed production of eastern black nightshade populations resistant (R) to AHAS inhibitors as conferred by an Ala205Val substitution in their AHAS. Growth and reproductive ability of four R and four susceptible (S) populations were determined in growth-cabinet and greenhouse studies. The R populations had lower total berry and viable seed production per plant than S under optimal conditions because of slower berry maturation. Seed production of both S and R populations decreased under lower or higher than optimal watering regimes; however, this reduction was more pronounced for the S populations so that seed production was comparable across S and R. The R populations had significantly higher germination and vegetative growth under cooler alternating temperature regimes. Although there were no differences between R and S plants under stress conditions, under optimal growth conditions, the Ala205Val substitution comes at a significant cost in eastern black nightshade. Under optimal growth conditions and in the absence of herbicide selection, S populations should eventually dominate over R; however, the lack of fitness differences under stress conditions could enhance the persistence of the R individuals.
Watt M.J.,Monash University |
Spriet L.L.,University of Guelph
American Journal of Physiology - Endocrinology and Metabolism | Year: 2010
Fatty acids derived from the hydrolysis of adipose tissue and skeletal muscle triacylglycerol (TG) are an important energy substrate at rest and during physical activity. This review outlines the identification of the new TG lipase, adipose triglyceride lipase, the current understanding of how cellular TG lipases are regulated, and the implications for understanding the integrated control of TG lipolysis. Furthermore, this review outlines recent advances that propose a "revised" role for TG lipases in cellular function, metabolic homeostasis, and disease prevention. Copyright © 2010 the American Physiological Society.
Munkholm L.J.,University of Aarhus |
Munkholm L.J.,University of Guelph
Geoderma | Year: 2011
This review gathers and synthesizes literature on soil friability produced during the last three decades. Soil friability is of vital importance for crop production and the impact of crop production on the environment. A friable soil is characterized by an ease of fragmentation of undesirably large aggregates/clods and a difficulty in fragmentation of minor aggregates into undesirable small elements. Soil friability has been assessed using qualitative field methods as well as quantitative field and laboratory methods at different scales of observation. The qualitative field methods are broadly used by scientists, advisors and farmers, whereas the quantitative laboratory methods demand specialized skills and more or less sophisticated equipment. Most methods address only one aspect of soil friability, i.e. either the strength of unconfined soil or the fragment size distribution after applying a stress. All methods have significant advantages and limitations. The use of a mixture of qualitative and quantitative methods to get a comprehensive and adequate assessment of soil friability is recommended. Poor friability can be experienced if soil is either too wet or too dry and there is a range in water contents for optimal friability. There is a strong need to get more detailed knowledge about effects of soil water content on soil friability and especially to be able to quantify the least limiting water range for soil friability and therefore soil tillage. A strong relationship between organic matter and friability has been found but it is not possible to identify a specific lower critical level of organic matter across soil types. Sustainable management of soil requires continuous and adequate inputs of organic matter to sustain or improve soil friability. Intensive tillage and traffic in unfavorable conditions threatens soil friability and may initiate a vicious cycle where increasingly higher intensity of tillage is needed to produce a proper seedbed. © 2011 Elsevier B.V..
Buechli M.E.,University of Guelph |
Lamarre J.,University of Guelph |
Koch T.G.,University of Guelph |
Koch T.G.,University of Aarhus
Stem Cells and Development | Year: 2013
MicroRNAs are a class of short noncoding RNAs that are involved in various biological processes, including differentiation. MicroRNA-140 (miR-140) has been identified as a cartilage-specific microRNA with several targets involved in cartilage development and homeostasis. The aim of this study was to investigate the expression of miR-140 during chondrogenic differentiation of equine cord blood-derived mesenchymal stromal cells (eCB-MSCs). We demonstrate both that miR-140 is highly expressed in normal equine articular cartilage and that eCB-MSCs express significantly higher levels of this microRNA after 14 days of chondrogenic differentiation. Furthermore, miR-140 expression closely paralleled that of the cartilage-specific transcription factor Sox9, suggesting that miR-140 may be under the transcriptional regulation of Sox9 in these cells. The expression patterns of miR-140 targets the chemokine (CXC motif) ligand 12 (CXCL12), A disintegrin and metalloproteinase with thrombosponin motifs (ADAMTS)-5 and insulin growth factor binding protein 5 (IGFBP5) were also determined; however, only CXCL12 and ADAMTS-5 were repressed while miR-140 expression was upregulated. Together, these studies suggest that miR-140 is an important regulator of cartilage development and homeostasis in eCB-MSCs that may act, in part, through the regulation of CXCL12 and ADAMTS-5. © Mary Ann Liebert, Inc.
Munkholm L.J.,University of Aarhus |
Munkholm L.J.,University of Guelph |
Heck R.J.,University of Guelph |
Deen B.,University of Guelph
Soil and Tillage Research | Year: 2013
Tillage and rotation are fundamental factors influencing soil quality and thus the sustainability of cropping systems. Many studies have focused on the effects of either tillage or rotation, but few have quantified the long term integrated effects of both. We studied the issue using a 30-year old long-term rotation and tillage treatment experiment on a Canadian silt loam soil. Topsoil measurements were carried out for three different rotations: R1, (C-C-C-C) continuous corn (Zea mays L.), R6, (C-C-O(RC), B(RC)) corn, corn, oats (Avena fatua L.) and spring barley (Hordeum vulgare L.) and R8, (C-C-S-S) corn, corn, soybean (Glycine max L.), soybean. A red clover (Trifolium pretense L.) cover crop was under seeded in oats and spring barley in R6. In 2010, first year corn was grown in R6 and R8. The tillage treatments included no tillage, NT and mouldboard ploughing, MP. Topsoil structural quality was visually evaluated in early June and mid October. Minimal disturbed soil cores collected in early June were used for X-ray CT scanning and to quantify water content and porosity. Soil friability was determined on the soil samples using a drop shatter test. Crop yield was determined and correlated to the soil quality estimates. We found significant effect of both rotation and tillage on visual soil structure at both times of assessment. Poor soil structure was found for NT except when combined with a diverse crop rotation (R6). The soil core pore characteristics data also displayed a significant effect of tillage but only a weak insignificant effect of rotation. The drop shatter results were in accordance with the visual assessment data. Crop yield correlated significantly with the visual soil structure scores. We conclude that a diverse crop rotation was needed for an optimal performance of NT for the studied soil. © 2012 Elsevier B.V.
Crow W.T.,U.S. Department of Agriculture |
Berg A.A.,University of Guelph |
Cosh M.H.,U.S. Department of Agriculture |
Loew A.,Max Planck Institute for Meteorology |
And 5 more authors.
Reviews of Geophysics | Year: 2012
The contrast between the point-scale nature of current ground-based soil moisture instrumentation and the ground resolution (typically >10 2 km 2) of satellites used to retrieve soil moisture poses a significant challenge for the validation of data products from current and upcoming soil moisture satellite missions. Given typical levels of observed spatial variability in soil moisture fields, this mismatch confounds mission validation goals by introducing significant sampling uncertainty in footprint-scale soil moisture estimates obtained from sparse ground-based observations. During validation activities based on comparisons between ground observations and satellite retrievals, this sampling error can be misattributed to retrieval uncertainty and spuriously degrade the perceived accuracy of satellite soil moisture products. This review paper describes the magnitude of the soil moisture upscaling problem and measurement density requirements for ground-based soil moisture networks. Since many large-scale networks do not meet these requirements, it also summarizes a number of existing soil moisture upscaling strategies which may reduce the detrimental impact of spatial sampling errors on the reliability of satellite soil moisture validation using spatially sparse ground-based observations. © 2012 by the American Geophysical Union.
News Article | February 15, 2017
Got BO? Blame the bacteria living in your armpits. In some people, bacteria cause body odour that no deodorant can disguise. But replacing them with underarm bacteria from a less smelly person can solve the problem, for a month or two at least. Our bodies are crawling with bacteria that have evolved with us and can affect our health. Disrupting the bacteria in our gut, for example has been linked to all kinds of intestinal, immune and brain disorders. The skin has its own microbiome too, and it varies by region – there can even be a difference between the bacterial ecosystem of your left and right armpits. The bacteria that live there probably have a role in producing the volatile compounds that give sweat its smell, says Chris Callewaert at the University of California, San Diego. A few years ago, Callewaert met a pair of identical twins – one of whom had particularly bad body odour. Callewaert suspected that the collection of bacteria living in the twins’ armpits might be responsible for their different personal scents. To find out, he swapped out the stinky twin’s armpit bacteria with that taken from his twin brother. Callewaert first asked the twin that didn’t smell to refrain from washing for four days. This is because the bacteria in our armpits live deep in the skin, so it takes a few days for them to be shed to the surface with dead skin. Meanwhile, the stinky twin scrubbed his pits with antibacterial soap every day, for four days. The idea was to remove as much of his armpit bacteria as possible, creating a clean state for his brother’s microbes. When Callewaert collected the nicer-smelling twin’s dead skin – which was loaded with his bacteria – and swabbed it in the armpits of the smellier twin, the man’s body odour problem rapidly disappeared. “The effects have persisted for over a year now,” says Callewaert. “We’re very happy with that. Callewaert and his colleagues have since repeated this procedure with 17 other pairs. In each case, one person in the pair had a body odour problem, and the other person was a close relative who was willing to donate bacteria from their armpit microbiome. Before and after the bacterial transplants, the offensiveness of the previously smelly people was judged by a “trained odour panel” of eight people, says Callewaert. Out of the 18 pairs, 16 saw improvements in body odour within a month. Half of the group had long-term improvements that lasted three months or more. Callewaert presented the results at the Karolinska Dermatology Symposium in Stockholm, Sweden, last month. “It’s very cool, and the idea is sound,” says Emma Allen-Vercoe at the University of Guelph in Ontario, Canada. “Some people suffer with body odour that’s really overwhelming,” she says. “Maybe the answer is to replace their microbes with ones that aren’t producing such volatile compounds.” She hopes that a similar approach might be useful in treating some skin conditions, like eczema and psoriasis. Callewaert and his colleagues are now formulating a more general brew of bacteria that could be used in place of a relative’s armpit scratchings. “It’s still very experimental, but I’m sure it can work,” he says. Until this is available, there are other ways you can improve your body odour bacteria. Microbes that feed on lipids – compounds that include fats and oils – are especially bad for body odour. You can try limiting the amount of lipids in your skin by keeping a healthy weight and avoiding fatty foods, says Callewaert. “People that eat fast food and meat smell worse, while those that eat vegetables smell better,” he says. Shaving can also help, as can wearing the right clothing. When we wear clothes, we transfer bacteria to them, and some fabrics encourage the growth of “bad” bacteria associated with offensive smells. Washing your clothes doesn’t solve the problem, either – it merely helps spread the bacteria among the contents of your washing machine. Polyester seems to be particularly bad, and is one to avoid, says Callewaert. Read more: These are the foods you should eat if you want less smelly farts
News Article | November 3, 2016
The number of outdoor cats in the city of Guelph is eye-raising, and these cats are more likely to be found in low-income residential areas, according to a new study from the University of Guelph. The researchers' study of outdoor felines appears as municipalities struggle to address issues of homeless cats, including bird deaths and nuisance complaints from residents. "Knowing the number of outdoor cats in our communities is the first step towards designing effective and humane management strategies for outdoor cat populations," said co-author Prof. Jason Coe, Department of Population Medicine. Based on 145 surveys around Guelph, the city has about 7,600 outdoor cats, or nearly 50 per city block. Guelph is home to 120,000 people. More cats live in low-income housing areas, according to the study, while fewer live around high-income commercial areas. "This is partly due to economic reasons but also ecological factors," said lead author Tyler Flockhart, a Liber Ero post-doctoral researcher at U of G. "We believe there are more cats in these areas because of increased opportunities for breeding, since in lower-income areas cats are less likely to be sterilized, and they have improved access to food sources. Cats also stay away from wooded areas where there may be more predators." By knowing where higher numbers of cats occur, "we can geographically target humane control methods for controlling outdoor cat populations as well as compare these populations to where birds occur in our communities to figure out where the greatest impact of cats on birds is," said co-author Prof. Ryan Norris, Department of Integrative Biology. The researchers counted cats on city streets, paths and alleys, and estimated totals for each survey area. The approach uses information readily available in most urban areas in North America, they said. "The study was done using techniques that are easy, quick and cheap, providing an opportunity to apply the method to any community that is interested in knowing their number of free-roaming outdoor cats," said Flockhart. "The hope is that we can bring together cat supporters and bird advocates to take actions to improve cat welfare and reduce the effect of outdoor cats on birds." The study was published in the journal Animal Conservation.
News Article | November 25, 2015
A silent crisis is brewing in Africa where current farming methods strip potassium out of soils faster than it is being replaced with fertilizer. University of Guelph Professor Peter Van Straaten estimates for Uganda there is a nutrient deficit of about 77 pounds per acre. “This is a silent crisis, and it continues if we are not addressing this problem,” Van Straaten told the first International Workshop on Alternative Potash at MIT on Nov. 11. African farmers are replacing just 10 percent of the potassium being removed with each harvest, creating “a recipe for disaster,” David Manning, professor of soil science at Newcastle University in the United Kingdom, said. Consumers in the Northern Hemisphere may not be paying a sufficiently price for products such as bananas to allow these farmers to replenish their soils with fertilizer, he suggested. “The current price is too high for many farmers. Demand is high because there is not enough potash going onto the land, so there’s a bottom line here that world production of potash would have double to meet the present day’s population. And that is clearly not possible,” Manning said. Potash is one of three main fertilizers needed for farming. The others are nitrogen and phosphorus. Representatives from the U.S., Canada, France, England, Brazil, the Ivory Coast, Malawi, and Tanzania gathered at MIT Nov. 10-12 for the public workshop and several closed sessions examining the scientific and economic status of efforts to develop alternatives to traditional potassium chloride salts. Africa has faced famines and malnutrition in part because of low fertilizer use, according to Mshindo Msolla, who is based in Tanzania with the African Fertilizer and Agribusiness Partnership. "This particular organization is trying to ensure that fertilizers are timely and delivered in the right quantities, which are soil- and crop-specific. Currently we are supporting these particular activities in Tanzania, Mozambique, Ghana, Nigeria, and the Ivory Coast. ... I'm here because potash deficiency is becoming very common in East Africa and specifically so for Tanzania as well," he said. "We don't have the resources, so we really need to look for these alternatives, alternative K [potassium] sources, using the locally available silicate minerals." Potash is plentiful in the Northern Hemisphere, where producers in Canada, Belarus, and Russia dominate the world market. Manning said three countries produce more than 70 percent of the world's potash, with little or no production in Africa, South Asia, and Australasia. "We have got a serious problem of geographic distribution," he said. Potash shortages affect parts of the Southern Hemisphere from Africa, to Brazil, to India and China. Manning suggested consumers think of the connection between the food they buy in grocery stores and the fertilizer needs of the world's farmers. Crops such as bananas sold in the U.S. and Europe are imported from countries with hot climates. "When we take a crop from the soil, we are taking nutrients from the soil. We are actually mining when we eat our food," he explained. "We need to reflect upon [this] when we are buying those supermarket products. ... Are we actually paying a price that is enough for the farmers to put the nutrients back in the soil?" Manning asked. A price war over bananas in the UK leads him to doubt whether farmers are being paid enough to get the potash that they need, he said. "Mining of fertilizers is an absolutely essential aspect to support human life," Manning said. The United Kingdom recently approved an underground potash mine deep in the North York Moors National Park to York Potash Ltd., which is a wholly owned subsidiary of Sirius Minerals PLC. York Potash will be extracting polyhalite, a mineral with agriculturally significant amounts of potassium, magnesium, sulfur, and calcium. "Polyhalite was mined in the U.S. in the 1920s, is now seen as a new product, and as well as potassium, it's adding calcium, magnesium, and sulfate, all of them beneficial," Manning said. Internationally, the current price for potash is about $300 per ton, Van Straaten noted. As of early November, he said, colleagues in Nairobi, Kenya, told him potash was going for $578 per ton there, while colleagues in Kampala, Uganda, told him it was unavailable. While the potassium salts mined in the Northern Hemisphere work well for countries there, alternative sources may be needed for the Southern Hemisphere. Both soils and the rock beneath them differ in tropical climates from those in the Northern Hemisphere. This year, agricultural crop production in Brazil will reach more than $110 billion. Brazil's fertilizer consumption in 2014 reached 15 million tons of phosphorus and nitrogen, and 6 million tons of potash. But Brazil is dependent on imports for 90 percent of its potash and fertilizer costs have risen over the past two decades from 5 percent to 30 percent of agricultural costs. Eder Martins, a researcher with the Brazilian Agricultural Research Corp. (Embrapa) in Brazil, noted studies have identified five different types of sources of potassium. New mapping techniques can point to which potash sources are most appropriate for which agricultural regions. One promising avenue is potassium from syenite, a mineral rock that contains up to 95 percent potassium feldspar. Researchers in the lab of Antoine Allanore, the Thomas B. King Assistant Professor of Metallurgy at MIT, working with partners at Embrapa in Brazil, have developed and tested a new hydrothermal technique for producing hydrosyenite, a potassium feldspar-based fertilizer. Greenhouse tests conducted by Embrapa's Cerrado Ecoregional Center in Brazil showed the alternative potassium fertilizer developed at MIT performed better on corn (maize) plants than potassium chloride salt fertilizer. The MIT process uses mechanical grinding and hydrothermal treatment of potassium feldspar. "From an industrial standpoint, benefitting from the fact that this microstructure reacts better to mechanical treatment means lower energy, which means lower cost, which means more scalability," Allanore said. The MIT research was funded by Brazilian minerals company Terrativa. "This new technology can change the production of potash in Brazil," Martins said. An advantage of hydrosyenite, or hydropotash, for the Cerrado area of Brazil, Allanore said, is that it also makes available silicon and other elements from the feldspar. The Cerrado soil has a desirable pH to capture aluminum so that it doesn't interfere with plant growth. "At end of day, you don't need to separate all the elements that constitute K-feldspar," he said. Cost estimates suggest a hydrosyenite plant requires one-third to one-half the capital needed for a new potassium chloride (KCl) mine. Operating costs are expected to be comparable to that of traditional KCl producers. "However, there is a big difference, which is the fact that now we don't need to go after traditional resources. We can actually directly implement this plant in a region close to the farmers who don't have access to KCl because of other reasons than the price of production in Canada or Russia, such as transportation and infrastructure." "We see a huge engagement from the representatives from Africa, which identifies clearly the same problems as in Brazil from an economic standpoint, and we are curious about how the development we've made in Brazil could be translated in Africa ... because the farmers are different, the crops are different, the soils are different," Allanore said. "That's one of the benefits of having this workshop; we can share experience from different regions all over the world, different economic situations, and then translate that into actions." Lisa Stillings, a research geologist with the U.S. Geological Survey and the University of Nevada at Reno, presented a detailed overview of various silicate mineral dissolution rate studies, both her own and those of other researchers. Not all silicate minerals contain potassium, so not all are appropriate as a potassium fertilizer source. Stillings said her research on feldspar, a potassium-bearing silicate, showed that on the surface of the dissolved feldspar mineral, the leach layer is thicker at more acidic solutions. A recent paper by Allanore group postdoc Davide Ciceri demonstrated through microfluidic experiments that feldspar interacting with a strong acid can release sufficient quantities of potassium for agriculture. Benedict S. Kanu, an agricultural specialist with the African Development Bank in the Ivory Coast, asked about the implications for Africa. Stillings noted that grinding the mineral to the finest particle size possible would increase the potassium dissolution rate. "Acidic conditions, if that's possible, and if there are any organic acids, that might also help to remove potassium from the structure," she added. Lab experiments show that continually altering soil conditions can recreate initial dissolution after mineral-based fertilizer is applied. Adding humic acid is one possible route to increase acidity. University of Guelph professor Peter Van Straaten specializes in agrogeology. "Agrogeology is a bridging science, but it's also part of a strategy of low external input, sustainable agriculture," he said. Bananas grow well on potassium rich volcanic rocks, such as sanidine, while corn does poorly on deeply weathered granite. Van Straaten has worked on projects in sub-Saharan Africa, Brazil, and Indonesia. "We try to involve farmers at the onset of a project, not the end," he said. Potassium salts (KCl) have over 60 percent K O and are mined from ore that contains 20 to 30 percent K O. Potassium silicates, such as potassium feldspar, contain 8 to 16 percent K O but have low solubility, Van Straaten said. (The alternative hydrosyenite developed at MIT contains about 12 percent K O.) "The challenge is to increase the rate of K release," he said. British researcher Manning said feldspar, for example, has a low dissolution rate compared with other potassium bearing minerals. Leucite is 10,000 times more soluble than potassium feldspar, he said. "These are the minerals we want to go for and that's because their dissolution rates are so high," he said. Such resources are however not always as large, abundant, and pure as K-feldspar, a reality that often prevents a cost-effective exploitation at large scale. "If we could process K (potassium) silicates locally at low cost, with appropriate technologies, there would be an abundance of K resources available to farmers, but it's not that easy," Van Straaten said. New geophysical tools are enabling rapid identification of soils that require potassium fertilizer. Van Straaten offered an alternative for dissolving unreactive phosphate mineral rock using a mush formed by Penicillium mold and Aspergillus niger fungus, which produces citric acid from the waste. The citric acid at least partially dissolves apatite mineral, which contains phosphorus but not potassium. The process is being used in Indonesia to make a biophosphate product. "It could be replicated in many places," he said. Many processes used for producing phosphorus could also be used for producing potassium, he added. Assistant Professor Edith LeCadre of Montpellier SupAgro and INRA in France presented research on the role of plant roots in dissolving potassium from feldspar in the soil. The immediate area of interaction between plant roots and soils is known as the rhizosphere. "Roots can weakly modify the physics, the chemistry, and the biology just near the roots, so it's only a few millimeters around the roots. But in this critical zone, you have an interaction between soil minerals and plants," she said. Roots, for example, release organic carbon that can be used by bacteria and fungi. Her research showed bioavailabilty of potassium after seven days from three different mineral rocks: potassium feldspar, syenite, and albite. "Plants can absorb much more potassium in the presence of soil," she said. Contributors to this effect include the buffering effect of the soil and organisms present in the soil. LeCadre worked with colleagues in Brazil and the Republic of Congo. Experiments near Sao Paulo, Brazil compared areas with reduced rainfall to unaltered areas and estimated the importance of potassium for plant production. The researchers also studied the effect of substituting sodium chloride (ordinary table salt) for potassium. "Sodium can, in a certain extent, replace potassium," she said. The researchers also measured root depth. Professor Jian-Ming Liu described an alternative fertilizer now being produced in China. His "soil conditioner" was licensed in China in 2012 after a decade of tests on 80 crops in 27 provinces, he said through a recorded presentation. Tests demonstrated improved quality and yield in tea plants and apple trees. Liu, who is a research professor at the Institute of Geology and Geophysics at the Chinese Academy of Sciences, applies a pressurized steam curing process to potassium-rich silicate rocks to make the multi-element fertilizer. "Plant roots can secrete root acids such as citric acid, acetic acid, which can easily flow along the micropores and dissolve the microcrystals of the product and absorb all the elements in the microcrystals," Liu explained. The Chinese product is unlikely to be effective for Brazil, however, Allanore said. "The chemistry principles behind the processing developed by Professor Liu and our group are the same; however, the processing parameters are very different and therefore will lead to a very different product. The soil conditioner product is typically very diluted in potash content, which is not good from a commercial perspective, and the product also goes for much longer time of processing and much more addition of additional activators, which at the end of the day makes it suitable for some very specific regions or specific markets but is probably not transposable. We cannot translate that very well in the context of Brazil, for example, where you have big farmers, huge scale, and big consumers." Plants like rice need silicon as well as the three major fertilizers, Manning noted. Both potassium and silicon occur in silicate minerals, but from a geochemical viewpoint they differ in their behavior. The sugar cane harvest in Thailand, for example, removes about 220 pounds, or $50 worth, of potassium for every 10 tons of sugar cane harvested, Manning said. "You're taking the potassium away. You need to put potassium back and if you don't do that, then potassium is being mined with every crop that's taken away," he said. Manning noted the UK grows about 6 million tons of potatoes in a good year. "That's $9 million worth of potash taken from our soils, and we put that back. We do replenish our soils with the nutrition that's taken away," he said.
Owen-Smith N.,University of Witwatersrand |
Fryxell J.M.,University of Guelph |
Merrill E.H.,University of Edmonton
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2010
We outline how principles of optimal foraging developed for diet and food patch selection might be applied to movement behaviour expressed over larger spatial and temporal scales. Our focus is on large mammalian herbivores, capable of carrying global positioning system (GPS) collars operating through the seasonal cycle and dependent on vegetation resources that are fixed in space but seasonally variable in availability and nutritional value. The concept of intermittent movement leads to the recognition of distinct movement modes over a hierarchy of spatio-temporal scales. Over larger scales, periods with relatively low displacement may indicate settlement within foraging areas, habitat units or seasonal ranges. Directed movements connect these patches or places used for other activities. Selection is expressed by switches in movement mode and the intensity of utilization by the settlement period relative to the area covered. The type of benefit obtained during settlement periods may be inferred from movement patterns, local environmental features, or the diel activity schedule. Rates of movement indicate changing costs in time and energy over the seasonal cycle, between years and among regions. GPS telemetry potentially enables large-scale movement responses to changing environmental conditions to be linked to population performance. ©2010 The Royal Society.
Murrant C.L.,University of Guelph |
Sarelius I.H.,University of Rochester
Journal of Physiology | Year: 2015
The focus of this review is on local mechanisms modifying arteriolar resistance to match blood flow to metabolism. In skeletal muscle many local mediators are known, including K+, nitric oxide (NO), purines and prostaglandins. Each accounts for about 30% of the response; it is widely held that these act redundantly: this concept awaits systematic testing. Understanding signal integration also requires consideration of microvascular network morphology in relation to local communication pathways between endothelial and smooth muscle cells (which are critical for many local responses, including dilatation to skeletal muscle contraction) and in relation to the spread of vasodilator signals up- and downstream throughout the network. Mechanisms mediating the spread of dilatation from local to remote sites have been well studied using acetylcholine (ACh), but remote dilatations to contraction of skeletal muscle fibres also occur. Importantly, these mechanisms clearly differ from those initiated by ACh, but much remains undefined. Furthermore, capillaries contribute to metabolic dilatation as they dilate arterioles directly upstream in response to vasoactive agents or contraction of adjacent muscle fibres. Given the dispersed arrangement of motor units, precise matching of flow to metabolism is not attainable unless signals are initiated only by 'active' capillaries. As motor units are recruited, signals that direct blood flow towards these active fibres will eventually be supported by local and spreading responses in the arterioles associated with those fibres. Thus, mechanisms of integration of vasodilator signalling across elements of the microvasculature remain an important area of focus for new studies. © 2015 The Physiological Society.
Chapman K.D.,University of North Texas |
Dyer J.M.,U.S. Department of Agriculture |
Mullen R.T.,University of Guelph
Journal of Lipid Research | Year: 2012
The compartmentation of neutral lipids in plants is mostly associated with seed tissues, where triacylglycerols (TAGs) stored within lipid droplets (LDs) serve as an essential physiological energy and carbon reserve during postgerminative growth. However, some nonseed tissues, such as leaves, flowers and fruits, also synthesize and store TAGs, yet relatively little is known about the formation or function of LDs in these tissues. Characterization of LD-associated proteins, such as oleosins, caleosins, and sterol dehydrogenases (steroleosins), has revealed surprising features of LD function in plants, including stress responses, hormone signaling pathways, and various aspects of plant growth and development. Although oleosin and caleosin proteins are specific to plants, LD-associated sterol dehydrogenases also are present in mammals, and in both plants and mammals these enzymes have been shown to be important in (steroid) hormone metabolism and signaling. In addition, several other proteins known to be important in LD biogenesis in yeasts and mammals are conserved in plants, suggesting that at least some aspects of LD biogenesis and/or function are evolutionarily conserved. Copyright © 2012 by the American Society for Biochemistry and Molecular Biology, Inc.
Lira V.A.,University of Virginia |
Benton C.R.,University of Guelph |
Yan Z.,University of Virginia |
Bonen A.,University of Guelph
American Journal of Physiology - Endocrinology and Metabolism | Year: 2010
The peroxisome proliferator-activated receptor-γ (PPARγ) coactivator-1α (PGC-1α) is a major regulator of exercise-induced phenotypic adaptation and substrate utilization. We provide an overview of 1) the role of PGC-1α in exercise-mediated muscle adaptation and 2) the possible insulin-sensitizing role of PGC-1α. To these ends, the following questions are addressed. 1) How is PGC-1α regulated, 2) what adaptations are indeed dependent on PGC-1α action, 3) is PGC-1α altered in insulin resistance, and 4) are PGC-1α-knockout and -transgenic mice suitable models for examining therapeutic potential of this coactivator? In skeletal muscle, an orchestrated signaling network, including Ca 2+-dependent pathways, reactive oxygen species (ROS), nitric oxide (NO), AMP-dependent protein kinase (AMPK), and p38 MAPK, is involved in the control of contractile protein expression, angiogenesis, mitochondrial biogenesis, and other adaptations. However, the p38γ MAPK/PGC-1α regulatory axis has been con-firmed to be required for exercise-induced angiogenesis and mitochondrial biogenesis but not for fiber type transformation. With respect to a potential insulinsensitizing role of PGC-1α, human studies on type 2 diabetes suggest that PGC-1α and its target genes are only modestly downregulated (≤34%). However, studies in PGC-1α-knockout or PGC-1α-transgenic mice have provided unexpected anomalies, which appear to suggest that PGC-1α does not have an insulin-sensitizing role. In contrast, a modest (∼25%) upregulation of PGC-1α, within physiological limits, does improve mitochondrial biogenesis, fatty acid oxidation, and insulin sensitivity in healthy and insulin-resistant skeletal muscle. Taken altogether, there is substantial evidence that the p38γ MAPK-PGC-1α regulatory axis is critical for exercise-induced metabolic adaptations in skeletal muscle, and strategies that upregulate PGC-1α, within physiological limits, have revealed its insulin-sensitizing effects. Copyright © 2010 the American Physiological Society.
Colwell S.R.,University of Guelph |
Joshi A.W.,York University
Business Strategy and the Environment | Year: 2013
Institutional theory argues that conformity to institutional pressure enhances the survival probability of organizations. Two key limitations of institutional theory have been proposed in recent literature: one, that it ignores the role of top management, and two, that it focuses only on survival as a benefit to the exclusion of more strategic benefits such as growth and profitability. In this research, we build a conceptual model that addresses both of these limitations in the context of institutional pressure on organizations to behave more responsibly vis-à-vis the natural environment. Results from a survey of 199 manufacturing firms show that the relationship between institutional pressure and corporate responsiveness to the pressure (i.e. corporate environmental responsiveness) is enhanced when top management commitment to the environment is high. Moreover, results show that organizational conformity to institutional pressure enhances the strategic benefits that organizations receive. © 2011 John Wiley & Sons, Ltd and ERP Environment.
Harauz G.,University of Guelph |
Boggs J.M.,Hospital for Sick Children |
Boggs J.M.,University of Toronto
Journal of Neurochemistry | Year: 2013
The classic myelin basic protein (MBP) splice isoforms range in nominal molecular mass from 14 to 21.5 kDa, and arise from the gene in the oligodendrocyte lineage (Golli) in maturing oligodendrocytes. The 18.5-kDa isoform that predominates in adult myelin adheres the cytosolic surfaces of oligodendrocyte membranes together, and forms a two-dimensional molecular sieve restricting protein diffusion into compact myelin. However, this protein has additional roles including cytoskeletal assembly and membrane extension, binding to SH3-domains, participation in Fyn-mediated signaling pathways, sequestration of phosphoinositides, and maintenance of calcium homeostasis. Of the diverse post-translational modifications of this isoform, phosphorylation is the most dynamic, and modulates 18.5-kDa MBP's protein-membrane and protein-protein interactions, indicative of a rich repertoire of functions. In developing and mature myelin, phosphorylation can result in microdomain or even nuclear targeting of the protein, supporting the conclusion that 18.5-kDa MBP has significant roles beyond membrane adhesion. The full-length, early-developmental 21.5-kDa splice isoform is predominantly karyophilic due to a non-traditional P-Y nuclear localization signal, with effects such as promotion of oligodendrocyte proliferation. We discuss in vitro and recent in vivo evidence for multifunctionality of these classic basic proteins of myelin, and argue for a systematic evaluation of the temporal and spatial distributions of these protein isoforms, and their modified variants, during oligodendrocyte differentiation. © 2013 International Society for Neurochemistry.
Chapman K.D.,University of North Texas |
Dyer J.M.,U.S. Department of Agriculture |
Mullen R.T.,University of Guelph
Plant Science | Year: 2013
Recent pressures to obtain energy from plant biomass have encouraged new metabolic engineering strategies that focus on accumulating lipids in vegetative tissues at the expense of lignin, cellulose and/or carbohydrates. There are at least three important factors that support this rationale. (i) Lipids are more reduced than carbohydrates and so they have more energy per unit of mass. (ii) Lipids are hydrophobic and thus take up less volume than hydrated carbohydrates on a mass basis for storage in tissues. (iii) Lipids are more easily extracted and converted into useable biofuels than cellulosic-derived fuels, which require extensive fractionation, degradation of lignocellulose and fermentation of plant tissues. However, while vegetative organs such as leaves are the majority of harvestable biomass and would be ideal for accumulation of lipids, they have evolved as "source" tissues that are highly specialized for carbohydrate synthesis and export and do not have a propensity to accumulate lipid. Metabolism in leaves is directed mostly toward the synthesis and export of sucrose, and engineering strategies have been devised to divert the flow of photosynthetic carbon from sucrose, starch, lignocellulose, etc. toward the accumulation of triacylglycerols in non-seed, vegetative tissues for bioenergy applications. © 2013.
Sentelhas P.C.,University of Sao Paulo |
Gillespie T.J.,University of Guelph |
Santos E.A.,University of Guelph
Agricultural Water Management | Year: 2010
Grass reference evapotranspiration (ETo) is an important agrometeorological parameter for climatological and hydrological studies, as well as for irrigation planning and management. There are several methods to estimate ETo, but their performance in different environments is diverse, since all of them have some empirical background. The FAO Penman-Monteith (FAO PM) method has been considered as a universal standard to estimate ETo for more than a decade. This method considers many parameters related to the evapotranspiration process; net radiation (Rn), air temperature (T), vapor pressure deficit (Δe), and wind speed (U); and has presented very good results when compared to data from lysimeters populated with short grass or alfalfa. In some conditions, the use of the FAO PM method is restricted by the lack of input variables. In these cases, when data are missing, the option is to calculate ETo by the FAO PM method using estimated input variables, as recommended by FAO Irrigation and Drainage Paper 56. Based on that, the objective of this study was to evaluate the performance of the FAO PM method to estimate ETo when Rn, Δe, and U data are missing, in Southern Ontario, Canada. Other alternative methods were also tested for the region: Priestley-Taylor, Hargreaves, and Thornthwaite. Data from 12 locations across Southern Ontario, Canada, were used to compare ETo estimated by the FAO PM method with a complete data set and with missing data. The alternative ETo equations were also tested and calibrated for each location. When relative humidity (RH) and U data were missing, the FAO PM method was still a very good option for estimating ETo for Southern Ontario, with RMSE smaller than 0.53 mm day-1. For these cases, U data were replaced by the normal values for the region and Δe was estimated from temperature data. The Priestley-Taylor method was also a good option for estimating ETo when U and Δe data were missing, mainly when calibrated locally (RMSE = 0.40 mm day-1). When Rn was missing, the FAO PM method was not good enough for estimating ETo, with RMSE increasing to 0.79 mm day-1. When only T data were available, adjusted Hargreaves and modified Thornthwaite methods were better options to estimate ETo than the FAO PM method, since RMSEs from these methods, respectively 0.79 and 0.83 mm day-1, were significantly smaller than that obtained by FAO PM (RMSE = 1.12 mm day-1). © 2009 Elsevier B.V. All rights reserved.
Peckett A.J.,York University |
Wright D.C.,University of Guelph |
Riddell M.C.,York University
Metabolism: Clinical and Experimental | Year: 2011
Glucocorticoids (GCs) have long been accepted as being catabolic in nature, liberating energy substrates during times of stress to supply the increased metabolic demand of the body. The effects of GCs on adipose tissue metabolism are conflicting, however, because patients with elevated GCs present with central adiposity. We performed an extensive literature review of the effects of GCs on adipose tissue metabolism. The contradictory effects of GCs on lipid metabolism occur through a number of different mechanisms, some of which are well defined and others remain to be elucidated. Firstly, through increases in caloric and dietary fat intake, along with increased hydrolysis of circulating triglycerides (chylomicrons, very low-density lipoproteins) by lipoprotein lipase activity, GCs increase the amount of fatty acids in circulation, which are then available for ectopic fat distribution (liver, muscle, and central adipocytes). Glucocorticoids also increase de novo lipid production in hepatocytes through increased expression of fatty acid synthase. There is some controversy as to whether these same mechanisms occur in adipocytes, thereby contributing to adipose hypertrophy. Glucocorticoids promote preadipocyte conversion to mature adipocytes, causing hyperplasia of the adipose tissue. Glucocorticoids also have acute antilipolytic effect on adipocytes, whereas their genomic actions facilitate increased lipolysis after about 48 hours of exposure. The acute and long-term effects of GCs on adipose tissue lipolysis remain unclear. Although considerable evidence supports the notion that GCs increase lipolysis through glucocorticoid-induced increases of lipase expression, they clearly have antilipolytic effects within these same tissues and cell line models. © 2011 Elsevier Inc.
Vega I.,University of Guelph |
Wardell B.,Max Planck Institute For Gravitationphysik |
Diener P.,Louisiana State University
Classical and Quantum Gravity | Year: 2011
Numerical evaluation of the self-force on a point particle is made difficult by the use of delta functions as sources. Recent methods for self-force calculations avoid delta functions altogether, using instead a finite and extended 'effective source' for a point particle. We provide a review of the general principles underlying this strategy, using the specific example of a scalar point charge moving in a black hole spacetime. We also report on two new developments: (i) the construction and evaluation of an effective source for a scalar charge moving along a generic orbit of an arbitrary spacetime, and (ii) the successful implementation of hyperboloidal slicing that significantly improves on previous treatments of boundary conditions used for effective-source-based self-force calculations. Finally, we identify some of the key issues related to the effective source approach that will need to be addressed by future work. © 2011 IOP Publishing Ltd.
Ni J.,Hohai University |
Zhang C.,Hohai University |
Yang S.X.,University of Guelph
IEEE Transactions on Power Delivery | Year: 2011
High-voltage circuit breakers (HVCBs) play an important role in power systems, which can control and ensure the power grids are working properly. Real-time fault diagnosis of HVCBs is an essential issue for power systems. In this paper, a novel approach based on an adaptive kernel principal component analysis (KPCA) and support vector machine (SVM) is proposed for real-time fault diagnosis of HVCBs. In the proposed approach, a sample reduction algorithm based on a similarity degree function is proposed to analyze the similarity between the samples, and the redundant data can be eliminated. An adaptive KPCA method is used for the fault detection of HVCBs based on squared prediction error statistics. An SVM is used to carry out the fault recognition. Two spare data areas are set up for fault detection and recognition modeling. The data in the spare date areas are updated continuously, and the detection and recognition models are updated subsequently to improve the adaptivity of the diagnosis models and reduce the diagnosis error. The proposed approach can deal with various situations of the fault diagnosis for HVCBs. The experimental results show that the proposed approach is capable of detecting and recognizing the faults efficiently. © 2011 IEEE.
Peiman K.S.,University of California at Los Angeles |
Robinson B.W.,University of Guelph
Quarterly Review of Biology | Year: 2010
Direct interactions among conspecific and heterospecific animals are often mediated by aggressive behavior. We analyze the ecology and evolution of resource-related heterospecific aggression (HA) by reviewing and meta-analyzing 126 studies, contrasting HA with conspecific aggression (CA), and discussing terminological confisions and conceptual models. HA occurred in 78% of tests (n = 459), suggesting a high prevalence and potential effect on niche use and community structure. The benefits of both CA and HA are linked to resource defensibility and abundance, yet HA can change independently of CA. Ecological inferences about HA are often weak because they assume that interference always results from resource competition, and evolutionary inferences made by comparing HA to CA are also weak because they usually ignore history. We believe that comparisons between situations where a focal species is attopatric from and sympatric with a heterospecific competitor provide better opportunities to test hypotheses about HA. In general according to our data set, aggression was higher with increased resource overlap as expected, both because CA was greater than HA, and HA was greater within compared to between genera. Progress in understanding HA requires distinguishing traits (aggressive behavior) from interactions (agonism, interference), as well as from the ecological and evolutionary causes (competition, ancestry) and consequences (dominance, territoriality, exclusion) of those interactions. Copyright © 2010 by The University of Chicago Press. All rights reserved.
Sun B.,Shanghai Maritime University |
Zhu D.,Shanghai Maritime University |
Yang S.X.,University of Guelph
IEEE Transactions on Industrial Electronics | Year: 2014
In this paper, a new approach of tracking control is investigated for the 7000-m Jiaolong manned submarine vehicle (MSV). First, the formulation of control allocation problem and some background information about tracking control of the 7000-m Jiaolong MSV are presented. Then, a kinematic controller is derived. The filter design using bioinspired model is employed to handle the speed jump problem and to make sure that each thruster is within the saturation limit. The kinematic controller is then extended to incorporate a sliding-mode control technique to complete the dynamic control. The system stability is guaranteed, and tracking errors asymptotically converge to zero by Lyapunov stability theory. Another interesting phenomenon is that the bioinspired method can achieve more satisfactory tracking result with a less control effort compared to a typical backstepping method. Finally, simulations illustrate the performance of the derived cascaded tracking control technique. © 2013 IEEE.
Webb N.P.,U.S. Department of Agriculture |
Okin G.S.,University of California at Los Angeles |
Brown S.,University of Guelph
Journal of Geophysical Research: Atmospheres | Year: 2014
Representation of surface roughness effects on aeolian sediment transport is a key source of uncertainty in wind erosion models. Drag partitioning schemes are used to account for roughness by scaling the soil entrainment threshold by the ratio of shear stress on roughness elements to that on the vegetated land surface. This approach does not explicitly account for the effects of roughness configuration, which may be important for sediment flux. Here we investigate the significance of roughness configuration for aeolian sediment transport, the ability of drag partitioning approaches to represent roughness configuration effects, and the implications for model accuracy. We use wind tunnel measurements of surface shear stress distributions to calculate sediment flux for a suite of roughness configurations, roughness densities, and wind velocities. Roughness configuration has a significant effect on sediment flux, influencing estimates by more than 1 order of magnitude. Measured and modeled drag partitioning approaches overestimate the predicted flux by 2 to 3 orders of magnitude. The drag partition is sensitive to roughness configuration, but current models cannot effectively represent this sensitivity. The effectiveness of drag partitioning approaches is also affected by estimates of the aerodynamic roughness height used to calculate wind shear velocity. Unless the roughness height is consistent with the drag partition, resulting fluxes can show physically implausible patterns. These results should make us question current assessments of the magnitude of vegetated dryland dust emissions. Representing roughness effects on surface shear stress distributions will reduce uncertainty in quantifying wind erosion, enabling better assessment of its impacts and management solutions. Key Points Roughness configuration has a significant effect on aeolian sediment flux Drag partition is sensitive to configuration but not captured in models Drag partition approaches overestimate flux by up to 3 orders of magnitude ©2014. American Geophysical Union. All Rights Reserved.
Barausse E.,University of Guelph |
Morozova V.,Max Planck Institute For Gravitationsphysik |
Rezzolla L.,Max Planck Institute For Gravitationsphysik |
Rezzolla L.,Louisiana State University
Astrophysical Journal | Year: 2012
We derive an analytic phenomenological expression that predicts the final mass of the black hole (BH) remnant resulting from the merger of a generic binary system of BHs on quasi-circular orbits. Besides recovering the correct test-particle limit for extreme mass-ratio binaries, our formula reproduces well the results of all the numerical-relativity simulations published so far, both when applied at separations of a few gravitational radii and when applied at separations of tens of thousands of gravitational radii. These validations make our formula a useful tool in a variety of contexts ranging from gravitational-wave (GW) physics to cosmology. As representative examples, we first illustrate how it can be used to decrease the phase error of the effective-one-body waveforms during the ringdown phase. Second, we show that, when combined with the recently computed self-force correction to the binding energy of nonspinning BH binaries, it provides an estimate of the energy emitted during the merger and ringdown. Finally, we use it to calculate the energy radiated in GWs by massive BH binaries as a function of redshift, using different models for the seeds of the BH population. © 2012. The American Astronomical Society. All rights reserved.
Barclay P.,University of Guelph |
Reeve H.K.,Cornell University
Behavioral Ecology | Year: 2012
Individuals of different quality often differ in their helping behavior, but sometimes it is the high-quality individuals who help most (e.g., human meat sharing, vigilance) and other times it is the low-quality individuals (e.g., reproductive queues, primate grooming). We argue that these differences depend on individual differences in the performance costs of actually helping, the opportunity costs from forsaking alternative activities, and the fitness benefits for engaging the help. If helping is more difficult for some individuals to do (quality-dependent help), it will usually be done by high-quality individuals, whereas help that all individuals could do equally well (quality-independent help) will be done by whoever pays lower opportunity costs. Our model makes novel predictions about many kinds of helping, allows us to categorize different types of helping by their relationship with individual quality, and is general enough to apply to many situations. Furthermore, it can be generalized to any other type of (nonhelping) behavior where there are individual differences in benefits, performance costs, or opportunity costs. © 2012 The Author.
Henson S.,University of Guelph |
Henson S.,University of Sussex
Agriculture and Human Values | Year: 2011
This paper concludes the special issue of Agriculture and Human Values devoted to private governance of global agri-food systems. Rather than aiming to summarize the findings of the various papers that make up the issue, it highlights a number of cross-cutting issues relating to the increasing role of private governance. Key issues that are discussed include the legitimacy of private governance of agri-food systems and the scope for trade-off between its various dimensions, private governance in a global context and the motivation for firms to engage in governance. Throughout, the major focus is on unresolved issues and on-going controversies with the intention of stimulating further research in this area. © 2011 Springer Science+Business Media B.V.
Martino T.A.,University of Guelph |
Young M.E.,University of Alabama at Birmingham
Journal of Biological Rhythms | Year: 2015
Cardiac function and dysfunction exhibit striking time-of-day-dependent oscillations. Disturbances in both daily rhythms and sleep are associated with increased risk of heart disease, adverse cardiovascular events, and worsening outcomes. For example, the importance of maintaining normal daily rhythms is highlighted by epidemiologic observations that night shift workers present with increased incidence of cardiovascular disease. Rhythmicity in cardiac processes is mediated by a complex interaction between extracardiac (e.g., behaviors and associated neural and humoral fluctuations) and intracardiac influences. Over the course of the day, the intrinsic properties of the myocardium vary at the levels of gene and protein expression, metabolism, responsiveness to extracellular stimuli/stresses, and ion homeostasis, all of which affect contractility (e.g., heart rate and force generation). Over the past decade, the circadian clock within the cardiomyocyte has emerged as an essential mechanism responsible for modulating the intrinsic properties of the heart. Moreover, the critical role of this mechanism is underscored by reports that disruption, through genetic manipulation, results in development of cardiac disease and premature mortality in mice. These findings, in combination with reports that numerous cardiovascular risk factors (e.g., diet, diabetes, aging) distinctly affect the clock in the heart, have led to the hypothesis that aberrant regulation of this mechanism contributes to the etiology of cardiac dysfunction and disease. Here, we provide a comprehensive review on current knowledge regarding known roles of the heart clock and discuss the potential for using these insights for the future development of innovative strategies for the treatment of cardiovascular disease. © 2015 The Author(s).
Ni J.,Hohai University |
Yang S.X.,University of Guelph
IEEE Transactions on Neural Networks | Year: 2011
Multiple robot cooperation is a challenging and critical issue in robotics. To conduct the cooperative hunting by multirobots in unknown and dynamic environments, the robots not only need to take into account basic problems (such as searching, path planning, and collision avoidance), but also need to cooperate in order to pursue and catch the evaders efficiently. In this paper, a novel approach based on a bioinspired neural network is proposed for the real-time cooperative hunting by multirobots, where the locations of evaders and the environment are unknown and changing. The bioinspired neural network is used for cooperative pursuing by the multirobot team. Some other algorithms are used to enable the robots to catch the evaders efficiently, such as the dynamic alliance and formation construction algorithm. In the proposed approach, the pursuing alliances can dynamically change and the robot motion can be adjusted in real-time to pursue the evader cooperatively, to guarantee that all the evaders can be caught efficiently. The proposed approach can deal with various situations such as when some robots break down, the environment has different boundary shapes, or the obstacles are linked with different shapes. The simulation results show that the proposed approach is capable of guiding the robots to achieve the hunting of multiple evaders in real-time efficiently. © 2011 IEEE.
Noble D.W.A.,University of Guelph |
Qi Y.,CAS Chengdu Institute of Biology |
Fu J.,University of Guelph
BMC Evolutionary Biology | Year: 2010
Background. Species are fundamental units in biology, yet much debate exists surrounding how we should delineate species in nature. Species discovery now requires the use of separate, corroborating datasets to quantify independently evolving lineages and test species criteria. However, the complexity of the speciation process has ushered in a need to infuse studies with new tools capable of aiding in species delineation. We suggest that model-based assignment tests are one such tool. This method circumvents constraints with traditional population genetic analyses and provides a novel means of describing cryptic and complex diversity in natural systems. Using toad-headed agamas of the Phrynocephalus vlangalii complex as a case study, we apply model-based assignment tests to microsatellite DNA data to test whether P. putjatia, a controversial species that closely resembles P. vlangalii morphologically, represents a valid species. Mitochondrial DNA and geographic data are also included to corroborate the assignment test results. Results. Assignment tests revealed two distinct nuclear DNA clusters with 95% (230/243) of the individuals being assigned to one of the clusters with > 90% probability. The nuclear genomes of the two clusters remained distinct in sympatry, particularly at three syntopic sites, suggesting the existence of reproductive isolation between the identified clusters. In addition, a mitochondrial ND2 gene tree revealed two deeply diverged clades, which were largely congruent with the two nuclear DNA clusters, with a few exceptions. Historical mitochondrial introgression events between the two groups might explain the disagreement between the mitochondrial and nuclear DNA data. The nuclear DNA clusters and mitochondrial clades corresponded nicely to the hypothesized distributions of P. vlangalii and P. putjatia. Conclusions. These results demonstrate that assignment tests based on microsatellite DNA data can be powerful tools for distinguishing closely related species and support the validity of P. putjatia. Assignment tests have the potential to play a significant role in elucidating biodiversity in the era of DNA data. Nonetheless, important limitations do exist and multiple independent datasets should be used to corroborate results from assignment programs. © 2010 Noble et al; licensee BioMed Central Ltd.
Gulseren T.,University of Guelph |
Fang Y.,Pepsi Cola Company |
Corredig M.,University of Guelph
Food Hydrocolloids | Year: 2012
Whey protein isolate (WPI) nanoparticles were prepared by diluting an alkaline solution of protein in ethanol at concentrations varying between 50 and 80%. The nanoparticles were then immediately diluted in buffer. While the nanoparticles were not stable at pH 7, they showed no changes in size when diluted at pH 3. When 75-80% ethanol was added during preparation, the size of the WPI nanoparticles ranged between 10 and 100 nm, with no change in size after dilution and storage at pH 3 for 96 h at 22 °C. When heating was applied, particle aggregation occurred, and large aggregates (>1 μm) were observed at temperatures > 60 °C. The particle size of the heat-induced aggregates could be reduced by homogenization. The nanoparticles prepared by desolvation showed interfacial pressure values similar to those of the corresponding protein solutions, indicating similar interfacial properties and the potential to be used to stabilize emulsions but as supramolecular aggregates of WPI. © 2012 Elsevier Ltd.
Gulseren I.,University of Guelph |
Fang Y.,Pepsi Cola Company |
Corredig M.,University of Guelph
Food Chemistry | Year: 2012
Whey protein isolate (WPI) nanoparticles were prepared using ethanol desolvation, and their capacity to incorporate ZnCl2 was analysed. Desolvation was carried out at pH 9 and the volume of added ethanol was 0-3 times the volume of protein solution. The desolvated solutions were dispersed in acidified water (pH 3) immediately after desolvation. The size of the WPI nanoparticles increased with the volume ratio of ethanol:water used, as well as with the amount of ZnCl2. The nanoparticles showed high incorporation efficiencies, and remained stable after 30 days of storage at 22°C. The amount of zinc incorporated in the WPI particle suspensions was within the range of daily zinc requirements for healthy adults. © 2012 Elsevier Ltd. All rights reserved.
University of Rochester, University of California at Los Angeles and University of Guelph | Date: 2013-09-18
The present invention relates to synthetic lung surfactant compositions that contain one or more of phospholipase-resistant phospho-glycerol derivatives, phospholipase-resistant phospho-choline derivatives, and surface active proteins or peptides, more preferably a combination of at least two or all three of these materials. Novel phospholipase-resistant phospho-glycerol derivatives, phospholipase-resistant phospho-choline derivatives, and surface active peptides are also disclosed herein. Uses of the surfactant compositions of the present invention to treat endogenous surfactant dysfunctional or deficient lung tissue, to prepare synthetic peptides for use in the surfactant compositions, and to deliver therapeutic agents are also disclosed.
Diener P.,Louisiana State University |
Vega I.,University of Guelph |
Wardell B.,Max Planck Institute For Gravitationphysik |
Wardell B.,University College Dublin |
Detweiler S.,University of Florida
Physical Review Letters | Year: 2012
The motion of a charged particle is influenced by the self-force arising from the particle's interaction with its own field. In a curved spacetime, this self-force depends on the entire past history of the particle and is difficult to evaluate. As a result, all existing self-force evaluations in curved spacetime are for particles moving along a fixed trajectory. Here, for the first time, we overcome this long-standing limitation and present fully self-consistent orbits and waveforms of a scalar charged particle around a Schwarzschild black hole. © 2012 American Physical Society.
News Article | March 2, 2017
A poultry analysis of various fast food restaurants from CBC Marketplace last week found that Subway's chicken may actually contain less chicken DNA than one would hope. Obviously, Subway wasn't too pleased with this study, and after releasing multiple statements disputing the report and demanding the piece be retracted, it released its own study. The original CBC report conducted by Matt Harnden, a researcher at Trent University's Wildlife Forensic DNA Laboratory, found that the chicken used in some of Subway's wraps and sandwiches contains less than 50 percent chicken DNA, with the remaining majority being soy. Of the six sandwiches tested from various restaurants, Subway's oven roasted chicken and chicken strips were the worst offenders. SEE ALSO: Taco Bell ditched the Naked Chicken Chalupa, so here's how to make your own “The stunningly flawed test by Marketplace is a tremendous disservice to our customers,” said Suzanne Greco, Subway president and chief executive, in a statement issued to the Washington Post Wednesday night. “The allegation that our chicken is only 50 percent chicken is 100 percent wrong.” So Subway released its own study conducted by two independent laboratories in order to test the chicken from Canada, the Post reports. The Subway studies evaluated the soy protein in the chicken samples, and found the plant protein to be less than 1 percent of the sample. CBC stood by its test results, posting the six page report for all to see on its site. "Only the Subway samples had significant levels of plant DNA," the CBC wrote. The CBC also cited Robert Hanner, biologist and associate director for the Canadian Barcode of Life Network at the University of Guelph in Ontario. "DNA tests do not lie (especially when conducted multiple times), and anyone with access to a DNA laboratory could perform these tests," Hanner wrote. The CBC also clarified part of its study, stating that "DNA tests don't reveal an exact percentage of the amount of chicken in the whole piece, but DNA experts have told Marketplace that the testing is a good indicator of the proportion of animal and plant DNA in the product." Subway declined to talk on camera about its study with CBC, and show where and how its chicken is made. Subway did not immediately respond to request for comment and additional information. UPDATE: March 2, 2017, 12:51 p.m. EST Subway provided the following statement in an email.
News Article | March 1, 2017
MONCTON, NEW BRUNSWICK--(Marketwired - March 1, 2017) - Organigram Holdings Inc. (TSX VENTURE:OGI) (OTCQB:OGRMF) (the "Company") has appointed a medical marijuana, pharmaceutical, and biotechnology industry veteran as its new chief executive officer. Greg Engel will assume his new role effective March 13, 2017. Mr. Engel succeeds Organigram's current CEO Denis Arsenault who is stepping up to the newly created executive chairman's position. Engel will also join the Board of Directors of Organigram, replacing Larry Rogers, who steps down from the Board, but remains an important part of the Senior Management team. Engel, 52, has served in a number of senior-level and executive positions in related industries over the past 25 years in Canada, US and Internationally. Most recently he was chief executive officer for Tilray Canada Inc., an early medical marijuana leader and the first Canadian company to export medical cannabis products to Europe. "We consider ourselves extremely fortunate to find and recruit Greg," said Arsenault. "Greg emerged as the leading candidate following an international search. His experience and leadership will be instrumental as we enter the next phase of our growth." Currently based in Toronto, Engel is familiar with Moncton having served as district sales manager in the pharmaceutical industry earlier in his career. "I consider this appointment an outstanding opportunity," he said. "Organigram is poised to become one of the world's leading marijuana producers; it will be gratifying to be part of a leadership team that helps the company achieve its goals." Engel is a native of Picton, ON and earned an Honours Bachelor of Science degree in Microbiology from the University of Guelph in 1987 and then studied marketing at Queen's University. He has also attended York University's Schulich School of Business. For his part, Arsenault said the decision to turn the day-to-day management of Organigram over to an executive of Engel's calibre has been planned for some time. "It has been 3 years to the day since I joined Organigram and I've achieved most of my goals as company CEO and believe it's time for me to pass the torch to a seasoned Executive with demonstrated leadership skills" he said. "I will stay active in the areas of Investor Relations and Capital Markets and look forward to working with Greg as he leads us through our next phase of expansion" he concluded. Arsenault also wanted to acknowledge the leadership of Monique Imbeault, who was Chairwoman of the Board over the past year, and remains an important part of our Board of Directors moving forward. Organigram Holdings Inc. is a TSX Venture Exchange listed company whose wholly owned subsidiary, Organigram Inc., is a licensed producer of medical marijuana in Canada. Organigram is focused on producing the highest quality, condition specific medical marijuana for patients in Canada. Organigram's facility is located in Moncton, New Brunswick and the Company is regulated by the Access to Cannabis for Medical Purposes Regulations ("ACMPR"). Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release. This news release contains forward-looking information which involves known and unknown risks, uncertainties and other factors that may cause actual events to differ materially from current expectation. Important factors - including the availability of funds, the results of financing efforts, crop yields - that could cause actual results to differ materially from the Company's expectations are disclosed in the Company's documents filed from time to time on SEDAR (see www.sedar.com). Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this press release. The Company disclaims any intention or obligation, except to the extent required by law, to update or revise any forward looking statements, whether as a result of new information, future events or otherwise.
News Article | April 22, 2016
If you talk to its proponents, and there are lots of them, sewage sludge fertilizer is a great way to divert human waste from landfills and to grow crops, despite the unappealing picture it may conjure. The US Environmental Protection Agency has a nicer name for the muck that’s left over after processing our shit—“biosolids”—and has encouraged its widespread use as a cheap, effective way to fertilize crops and recycle human waste. But while the EPA requires that bacteria and viruses are killed off before sludge is applied to farm fields, other contaminants, like pharmaceuticals and metals, are only minimally regulated, if at all. New research suggests this could be a problem, as contaminants are now showing up in treated sludge—and, in lower levels, even in some animals that have fed off the plants it fertilizes. “I don’t think the present rules are even remotely adequate,” Murray McBride, a soil contaminant researcher at Cornell University, told me. “There are a lot more toxic metals on the periodic table [and potentially in the soil] than what they decided to regulate.” According to him, the EPA’s rules are outdated. They regulate only nine metals with known health risks—including lead, cadmium and arsenic. And metals are just the beginning. Pharmaceuticals and other organic chemicals found in biosolids are cause for even greater concern, he said. Others agree. “If you look at what [could be] potentially regulated by EPA, it’s just a tiny fraction of the universe of the chemicals we live in,” David L. Lewis, a former EPA scientist who is now a fierce critic of the agency, told me. Cities like San Diego turn their sewage into fertilizer. Photo: William Garrett/Flickr EPA officials haven’t said whether the rules will be revised, but agency spokesperson Robert Daguillard noted in an email that the agency plans to assess the risks posed by pharmaceuticals in sludge. While they haven’t yet determined these risks, they do know what’s in it. An EPA sludge survey, Daguilllard said, includes “92 pharmaceuticals, steroids, and hormones.” But none of those are actually subject to enforceable limits under current rules. For many farmers, biosolids are a cheaper alternative to synthetic fertilizers. Municipal governments like them, too: since some cities divert as much as 50 percent of sludge to farms, they can reduce the amount of waste they have to pay to landfill. San Diego, Portland and Edmonton, among many others, process their waste to produce biosolids. It makes sense, then, that demand has been increasing. While the EPA hasn’t recently estimated the size of the market, it put biosolids production at 7.2 million tons in 2004, up four percent from six years earlier. If that growth rate has continued roughly apace, production would be near 8 million tons today. Organic farmers can’t use biosolids as fertilizer without risking their organic certification, but it’s relatively easy for others to get, often via local organizations. Biosolids boosters say the fertilizer is effective. “If there are any small negative impacts [from contaminants], they are overwhelmed by the positive effects” on crop yields, said Ned Beecher of Northeast Biosolids and Residuals Association, which promotes its use. He believes that the EPA rules are adequate as-is, noting that the agency has already considered the risks posed by dozens of sludge contaminants, and judged them minimal. “Just because there is no limit set, doesn’t mean risk assessment hasn’t been done,” Beecher told me. Before sewage sludge is used on farm fields, the EPA requires that it undergo two processes aimed at destroying pathogens: anaerobic digestion—in which bacteria break sludge down in the absence of oxygen––and high-heat sterilization. Even so, some suggest that enough bacteria may survive to contribute to the spread of antibiotic-resistant strains. That’s a major concern, because when these “superbugs” spread in livestock farms and hospitals, disease can run rampant. And the bacteria can’t be easily killed with penicillin or other antibiotics. Edo McGowan, a retired environmental scientist and outspoken critic of biosolids, is concerned about research showing antibiotic-resistance genes in soils treated with biosolids. These genes, he said, are easily spread by farm equipment or wind, winding up in bacteria that can be ingested by people and animals. “Some of these bugs are resistant to pretty much anything you can throw at them,” he told me. Not all experts agree that using biosolids as fertilizer is hurting the effectiveness of antibiotics, mostly because we still don’t know how much disease resistance occurs naturally in soils. “It’s just speculation at this point,” said Marc Habash, who researches microbes in biosolids at the University of Guelph in Ontario. “Antibiotic resistance genes are in our soil. There are a lot of natively-occurring bacteria that possess these genes.” Earthworms seem to have picked up some contaminants. Photo: schizoform/Flickr Research has backed up some of the critics. A 2012 study led by environmental chemist Chad Kinney of Colorado State University, Pueblo, found that earthworms in soil treated with biosolids contained a variety of manmade compounds, including pharmaceuticals and personal care products, like the antibiotic drug trimethoprim (used to treat urinary tract infections and other conditions) and the disinfectant triclosan (a common ingredient in antibacterial hand soap). Whether those synthetic compounds actually harm earthworms is unknown, and Kinney notes that the concentrations are low. But he said their presence shows that manmade contaminants in biosolids are moving up the food web. This suggests they could be reaching humans, too. Despite his worrisome findings, Kinney said that the risks of biosolids are mostly speculative and hard to measure, while the benefits are clear: it’s a way to keep sewage sludge out of landfills and return nutrients to soil. “If sludge isn’t meeting the regulatory requirements [to be classified] as biosolids, it has to be disposed some way. But then you lose all that valuable organic carbon and nutrients that can be released into a soil environment.” Any health risks associated with recycling contaminants in fertilizer and sending them up the food web may not be known for generations—if ever, according to Kinney. Part of the problem, he said, is that most studies look only for immediate damage or death, not slower, less obvious effects like reductions in fertility. “Most of the toxicology is based on acute studies of one compound in short-term exposure,” Kinney told Motherboard. “What’s happening in natural environments is long term exposure to low concentrations, so you’re not going to see those acute effects per se. We’re not going to see typical things like lethality.” “It’s going to be slower, subtler effects,” he said, “that have generational effects.”
News Article | July 7, 2016
Ticked Off! Here's What You Need To Know About Lyme Disease No, it's not a fire-breathing bee, but it's what you get when a Pokémon fan is a scientist. Spencer K. Monckton is currently a PhD student at the University of Guelph in Canada. When he was taking his Biology Master's degree at the York University, he discovered eight new species of bees, one of which he named the Chilicola charizard or the stem-nesting Charizard. Getting to name a species is a perk when you discover one and Monckton used this opportunity to show his love for Pokémon. "I played the game pretty much from when it was released and I picked Charmander when I first started the game," he said. In the game, Charmander evolves into Charmeleon, which then evolves into Charizard. While Monckton could have named the bee species he discovered just because he could, he actually has a logical reason behind the name: the bee has a long snout and an orange hue. The stem-nesting Charizard belongs to a subgenus of bees that has 17 species all endemic to various parts of Chile. In a study published in ZooKeys, Monckton described the bee species he discovered, including the stem-nesting Charizard, noting the tiny creatures typically measure 4 to 7 mm (0.16 to 0.28 inch) long. And where the stem-nesting Charizard has orange markings, others discovered by Monckton feature yellow hues. However, the yellow markings can also turn orange when a specimen is preserved, which is actually how Monckton made comparisons for his research. He also detailed a way to make it easier to tell apart the males from the females of the bee species in the study. The stem-nesting Charizard and Monckton's other bee discoveries are polyester bees. They are called as such because they produce secretions that dry into a smooth and cellophane-like material when applied to the walls of nest cells. The bees are solitary so while they can be found all over Chile — from moist forests to arid deserts and coastal areas to thousands of feet above sea level — they don't nest in groups in the hollows of plant stems. As someone who actively seeks out organisms to group and classify, Monckton is a lot like a real-life Pokémon trainer filling up his Pokédex. He now has a Charizard, but what's next? Maybe he can play Pokémon GO for now, whiling the days away catching virtual Pokémon while making his way to his next discovery. © 2016 Tech Times, All rights reserved. Do not reproduce without permission.
Filipova-Neumann L.,University of Augsburg |
Hoy M.,University of Guelph
Journal of Health Economics | Year: 2014
There is a prospect in the medium to long term future of substantial advancements in the understanding of the relationship between disease and genetics. We consider the implications of increased information from genetic tests about predisposition to diseases from the perspective of managing health care provision under a public health insurance scheme. In particular, we consider how such information may potentially improve the targeting of medical surveillance (or prevention) activities to improve the chances of early detection of disease onset. We show that the moral hazard implications inherent in surveillance and prevention decisions that are chosen to be privately rather than socially optimal may be exacerbated by increased information about person-specific predisposition to disease. © 2014 Elsevier B.V.
Teplitski M.,University of Florida |
Warriner K.,University of Guelph |
Bartz J.,University of Florida |
Schneider K.R.,University of Florida
Trends in Microbiology | Year: 2011
Recent outbreaks of vegetable-borne gastrointestinal illnesses across the globe demonstrate that human enteric pathogens can contaminate produce at any stage of production. Interactions of enterics with native plant-associated microbiota influence the microbiological safety of produce by affecting the attachment, persistence and proliferation of human pathogens on plants. Supermarket surveys have revealed that bacteria, but not fungi or mechanical damage, promote the growth of Salmonella enterica on produce. Field and laboratory studies have indicated that some plant pathogenic bacteria and fungi facilitate the entry and internalization of human pathogens in plants. Conversely, some phytobacteria, including those involved in biocontrol of plant diseases, significantly inhibit attachment and plant colonization by non-typhoidal Salmonella and enterovirulent Escherichia coli by producing antibiotics or competing for nutrients in the phyllosphere. In this review, we attempt to elucidate the mechanisms of interactions between human enteric pathogens and plant-associated microbiota, and describe how these interactions affect produce safety. © 2010 Elsevier Ltd.
Xiao Q.,Jiangnan University |
Lim L.-T.,University of Guelph |
Tong Q.,Jiangnan University
Carbohydrate Polymers | Year: 2012
Pullulan-sodium alginate blend films were prepared and characterized as a function of water activity (aw). At low aw, the incorporation of alginate into pullulan film increased the tensile strength and elastic modulus, but decreased the elongation at break of the composite films; the opposite trends were observed at elevated aw. Above 0.43 a w, water exerted a typical plasticization effect upon the biopolymer blends. As aw increased from 0.23 to 0.43, an anti-plasticization effect was observed as tensile strength and elastic modulus increased. The glass transition temperature of all samples decreased substantially as aw increased from 0.23 to 0.84 due to the plasticization effect of water. Within this a w range, one transition temperature was observed for all film specimens. The stretching vibration band of O-H was investigated using attenuated total reflection Fourier transform infrared spectroscopy to identify the various species of water interacting with the polysaccharide films. © 2011 Elsevier Ltd. All Rights Reserved.
Xiao Q.,Jiangnan University |
Tong Q.,Jiangnan University |
Lim L.-T.,University of Guelph
Carbohydrate Polymers | Year: 2012
Rheological properties of pullulan, sodium alginate and blend solutions were studied at 20 °C, using steady shear and dynamic oscillatory measurements. The intrinsic viscosity of pure sodium alginate solution was 7.340 dl/g, which was much higher than that of pure pullulan (0.436 dl/g). Pure pullulan solution showed Newtonian behavior between 0.1 and 100 s-1 shear rate range. However, increasing sodium alginate concentration in pullulan-alginate blend solution led to a shear-thinning behavior. The effect of temperature on viscosities of all solutions was well-described by Arrhenius equation. Results from dynamical frequency sweep showed that pure sodium alginate and blend solutions at 4% (w/w) polymer concentration were viscoelastic liquid, whereas the pure pullulan exhibited Newtonian behavior. The mechanical properties of pure sodium alginate and pullulan-alginate mixture were analyzed using the generalized Maxwell model and their relaxation spectra were determined. Correlation between dynamic and steady-shear viscosity was analyzed with the empirical Cox-Merz rule. © 2011 Elsevier Ltd. All rights reserved.
Glatz J.F.C.,Maastricht University |
Luiken J.J.F.P.,Maastricht University |
Bonen A.,University of Guelph
Physiological Reviews | Year: 2010
Long-chain fatty acids and lipids serve a wide variety of functions in mammalian homeostasis, particularly in the formation and dynamic properties of biological membranes and as fuels for energy production in tissues such as heart and skeletal muscle. On the other hand, long-chain fatty acid metabolites may exert toxic effects on cellular functions and cause cell injury. Therefore, fatty acid uptake into the cell and intracellular handling need to be carefully controlled. In the last few years, our knowledge of the regulation of cellular fatty acid uptake has dramatically increased. Notably, fatty acid uptake was found to occur by a mechanism that resembles that of cellular glucose uptake. Thus, following an acute stimulus, particularly insulin or muscle contraction, specific fatty acid transporters translocate from intracellular stores to the plasma membrane to facilitate fatty acid uptake, just as these same stimuli recruit glucose transporters to increase glucose uptake. This regulatory mechanism is important to clear lipids from the circulation postprandially and to rapidly facilitate substrate provision when the metabolic demands of heart and muscle are increased by contractile activity. Studies in both humans and animal models have implicated fatty acid transporters in the pathogenesis of diseases such as the progression of obesity to insulin resistance and type 2 diabetes. As a result, membrane fatty acid transporters are now being regarded as a promising therapeutic target to redirect lipid fluxes in the body in an organ-specific fashion. Copyright © 2010 the American Physiological Society.
Allen-Vercoe E.,University of Guelph |
Jobin C.,University of Florida
Immunology Letters | Year: 2014
The gut microbiota plays an essential role in regulating intestinal homeostasis through its capacity to modulate various biological activities ranging from barrier, immunity and metabolic function. Not surprisingly, microbial dysbiosis is associated with numerous intestinal disorders including inflammatory bowel diseases (IBD) and colorectal cancer (CRC). In this piece, we will review recent evidence that gut microbial dysbiosis can influence intestinal disease, including colitis and CRC. We will discuss the biological events implicated in the development of microbial dysbiosis and the emergence of CRC-associated microorganisms, focusing on Escherichia coli and Fusobacterium nucleatum. Finally, the mechanisms by which E. coli and F. nucleatum exert potentially carcinogenic effects on the host will be reviewed. © 2014 Elsevier B.V..
Barausse E.,University of Guelph |
Barausse E.,University Pierre and Marie Curie |
Sotiriou T.P.,International School for Advanced Studies |
Sotiriou T.P.,National Institute of Nuclear Physics, Italy
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013
In a recent paper we claimed that there are no slowly rotating, stationary, axisymmetric black holes in the infrared limit of Hořava-Lifshitz gravity, provided that they are regular everywhere apart from the central singularity. Here we point out a subtlety in the relation between Einstein-æther theory and the infrared limit of Hořava-Lifshitz gravity which was missed in our earlier derivation and drastically modifies our conclusion: our earlier calculations (which are otherwise technically correct) do not really imply that there are no slowly rotating black holes in Hořava-Lifshitz gravity, but that there are no slowly rotating black holes in the latter that are also solutions of Einstein-æther theory and vice versa. That is, even though the two theories share the static, spherically symmetric solutions, there are no slowly rotating black holes that are solutions to both theories. We proceed to generate slowly rotating black-hole solutions in the infrared limit of Hořava-Lifshitz gravity, and we show that the configuration of the foliation-defining scalar remains the same as in spherical symmetry, thus these black holes are expected to possess a universal horizon. © 2013 American Physical Society.
Pimchuai A.,Burapha University |
Dutta A.,University of Guelph |
Basu P.,Dalhousie University
Energy and Fuels | Year: 2010
Torrefaction improves the thermochemical properties of biomass that are relevant to combustion, co-combustion with coal, or gasification. This study examines torrefaction of rice husks and four other agriculture residues (sawdust, peanut husks, bagasse, and water hyacinth) in nitrogen. Two main operating parameters of torrefaction, temperature and residence time for the process, were varied in the range of 250-300 °C and 1-2 h, respectively. Product evolution and mass and energy losses during torrefaction were measured. Similar to other work, the torrefied products in the present work were characterized by a more brownish color, reduced moisture content and volatile matter, and increased ash, fixed carbon content, and energy density. The difference between the mass and energy yield was shown to improve for the higher torrefaction temperatures investigated. For the biomass studied, the torrefied bagasse at 300 °C and 1.5 h resulted in the highest higher heating value (HHV) of 25.68 MJ/kg of product, which was comparable to the HHV of lignite. Dependent upon the severity of the torrefaction conditions, the torrefied fuel can contain up to 98% of the original energy content on a mass basis. The combustion behavior of both raw and torrefied rice husks was studied in a spout-fluid bed combustor by measuring its temperature history at different zones. It is observed that torrefied husks ignite faster and raise the bed temperature to a higher level because of its low moisture content. © 2010 American Chemical Society.
Bauch C.T.,University of Guelph |
Li M.,Rutgers University |
Chapman G.,Rutgers University |
Galvani A.P.,Yale University
The Lancet Infectious Diseases | Year: 2010
Human papillomavirus vaccine prevents infection by two major oncogenic types of the virus. Continued screening is needed in vaccinated women to prevent cancers caused by high-risk types not included in the vaccine. An exaggerated sense of protection from the vaccine could lead to a decline in the rate of screening among vaccinated women, which in principle could lead to an increase in the incidence of cervical cancer. We present a simple mathematical model of vaccination, screening, and disease incidence, including an analysis of the effect of data uncertainties. For a population with opportunistic screening and 30% vaccine coverage, screening rates in vaccinated women would have to decline by at least 80% (median value of probabilistic uncertainty analysis) before the incidence of cervical cancer would increase in the era since the introduction of the vaccine. By comparison, the decline needed is at least 49% in a population with organised screening and 70% vaccine coverage. In populations that have highly effective cervical screening programmes, incidence of cervical cancer starts to increase after smaller, but still substantial, decreases in screening. Introduction of vaccine is unlikely to lead to an increased incidence of cervical cancer as a result of diminished screening. © 2010 Elsevier Ltd. All rights reserved.
Zinsstag J.,Swiss Tropical and Public Health Institute |
Schelling E.,Swiss Tropical and Public Health Institute |
Waltner-Toews D.,University of Guelph |
Tanner M.,Swiss Tropical and Public Health Institute
Preventive Veterinary Medicine | Year: 2011
Faced with complex patterns of global change, the inextricable interconnection of humans, pet animals, livestock and wildlife and their social and ecological environment is evident and requires integrated approaches to human and animal health and their respective social and environmental contexts. The history of integrative thinking of human and animal health is briefly reviewed from early historical times, to the foundation of universities in Europe, up to the beginning of comparative medicine at the end of the 19th century. In the 20th century, Calvin Schwabe coined the concept of " one medicine" It recognises that there is no difference of paradigm between human and veterinary medicine and both disciplines can contribute to the development of each other. Considering a broader approach to health and well-being of societies, the original concept of " one medicine" was extended to " one health" through practical implementations and careful validations in different settings. Given the global health thinking in recent decades, ecosystem approaches to health have emerged. Based on complex ecological thinking that goes beyond humans and animals, these approaches consider inextricable linkages between ecosystems and health, known as " ecosystem health" Despite these integrative conceptual and methodological developments, large portions of human and animal health thinking and actions still remain in separate disciplinary silos. Evidence for added value of a coherent application of " one health" compared to separated sectorial thinking is, however, now growing. Integrative thinking is increasingly being considered in academic curricula, clinical practice, ministries of health and livestock/agriculture and international organizations. Challenges remain, focusing around key questions such as how does " one health" evolve and what are the elements of a modern theory of health? The close interdependence of humans and animals in their social and ecological context relates to the concept of " human-environmental systems" , also called " social-ecological systems" The theory and practice of understanding and managing human activities in the context of social-ecological systems has been well-developed by members of The Resilience Alliance and was used extensively in the Millennium Ecosystem Assessment, including its work on human well-being outcomes. This in turn entails systems theory applied to human and animal health. Examples of successful systems approaches to public health show unexpected results. Analogous to " systems biology" which focuses mostly on the interplay of proteins and molecules at a sub-cellular level, a systemic approach to health in social-ecological systems (HSES) is an inter- and trans-disciplinary study of complex interactions in all health-related fields. HSES moves beyond " one health" and " eco-health" , expecting to identify emerging properties and determinants of health that may arise from a systemic view ranging across scales from molecules to the ecological and socio-cultural context, as well from the comparison with different disease endemicities and health systems structures. © 2010 Elsevier B.V.
Gellert R.,University of Guelph |
Clark B.C.,Space Science Institute
Elements | Year: 2015
The Alpha Particle X-ray Spectrometer (APXS) is a soda can-sized, arm-mounted instrument that measures the chemical composition of rocks and soils using X-ray spectroscopy. It has been part of the science payload of the four rovers that NASA has landed on Mars. It uses 244Cm sources for a combination of PIXE and XRF to quantify 16 elements. So far, about 700 Martian samples from about 50 km of combined traverses at the four landing sites have been documented. The compositions encountered range from unaltered basaltic rocks and extensive salty sandstones to nearly pure hydrated ferric sulfates and silica-rich subsurface soils. The APXS is used for geochemical reconnaissance, identification of rock and soil types, and sample triage. It provides crucial constraints for use with the mineralogical instruments. The APXS data set allows the four landing sites to be compared with each other and with Martian meteorites, and it provides ground truth measurements for comparison with orbital observations.
Barausse E.,University of Guelph |
Sotiriou T.P.,International School for Advanced Studies |
Sotiriou T.P.,National Institute of Nuclear Physics, Italy
Physical Review Letters | Year: 2012
We consider slowly rotating, stationary, axisymmetric black holes in the infrared limit of Hořava-Lifshitz gravity. We show that such solutions do not exist, provided that they are regular everywhere apart from the central singularity. This has profound implications for the viability of the theory, considering the astrophysical evidence for the existence of black holes with nonzero spin. © 2012 American Physical Society.
Holdo R.M.,University of Missouri |
Holt R.D.,University of Florida |
Fryxell J.M.,University of Guelph
Oikos | Year: 2013
Theoretical models of tree-grass coexistence in savannas have focused primarily on the role of resource availability and fire. It is clear that herbivores heavily impact vegetation structure in many savannas, but their role in driving tree-grass coexistence and the stability of the savanna state has received less attention. Theoretical models of tree-grass dynamics tend to treat herbivory as a constant rather than a dynamic variable, yet herbivores respond dynamically to changes in vegetation structure in addition to modifying it. In particular, many savannas host two distinct herbivore guilds, grazers and browsers, both of which have the potential to exert profound effects on tree/grass balance. For example, grazers may indirectly favor tree recruitment by suppressing the destructive effects of fire, and browsers may facilitate the expansion of grassland by reducing the competitive dominance of trees. We use a simple theoretical model to explore the role of grazer and browser dynamics on savanna vegetation structure and stability across fire and resource availability gradients. Our model suggests that herbivores may expand the range of conditions under which trees and grasses are able to stably coexist, as well as having positive reciprocal effects on their own niche spaces. In addition, we suggest that given reasonable assumptions, indirect mutualisms can arise in savannas between functional groups of herbivores because of the interplay of consumption and ecosystem feedbacks. © 2012 The Authors. Oikos © 2012 Nordic Society Oikos.
News Article | November 18, 2016
— Venus Factor is a guide which provides a complete course of actions with traditional knowledge equipped with advanced methods to dwindle negative energy and provide energy to perform unique yet simple postures described in the workout section. This book involves advanced and quick deals apportioned nicely for elevating energy and endurance. According to its official website complications regarding overweight women along with progressing age factor is perfectly defined. This has also created an alarming situation and an increase in demand for reducing weight. Read More: Nutritionists Recommend The Perfect Dinner Equation For Weight Loss Using the metabolic override which is known as a unique set of exercises accompanied with low in calorie but high fiber foods successfully overcome the need of hunger. It also cuts the fancy diet craving which is just a mere want of nervous system to divert itself from being in the state of boredom. According to the official website of Venus Factor, “Venus Factor modifies these unique diet and exercise strategies to the woman as an individual based on her current measurements, personal food preferences, schedule and exercise capabilities in order to help maximize her results. Custom nutritional software, meal plans and workout videos are provided as part of a distinct four phase plan Venus Factor uses to help women experience healthy weight loss.” Special qualities in Venus Factor that doesn’t require to sacrifice anyone’s favorite meal Venus Factor would keep everyone wondering with how it optimizes ideal weight by providing a better lifestyle. It provides scheduled diet routine that is not strict nor the inclusive recipes are tasteless. It doesn’t even require starvation or fasting methods to overcome weight issue. The best logic that has been specified in this course is that weight can only be controlled and balanced if a person is willing to spare time for themselves otherwise, it can never be altered with medications, drugs or weight loss pills. Instant access to download The Venus Factor, plus receive the complete physical collection Created by Jon Barban, who is best known for his widely sold book, multiple diet and fitness programs. He holds a master’s degree from the University of Guelph in Human Biology and Nutrition. He then did his specialization from the University of Florida whilst working there a faculty too in the department of Health and Human performance. He also has widespread clinical experience working in the health and sports supplement industry in research and development contributing as a consultant. It took him 10years to blend his knowledge and experience for compiling a master piece like Venus Factor. Venus factor is an interactive 12-weeks program with video tutorials and an E-Book comprising of 180 pages. Including all necessary information on how to avoid foods enriched with carbohydrates that stimulates fat producing agents. To have further information check Venus Factor’s official website This complete course book is available at an affordable price of $37. With book digital and physical collection package. They also offer 24/7 customer support via their email help desk at firstname.lastname@example.org. Also, they have a facility to call their customer representative which facilitates all the queries quiet well. their toll free number: (844) 687-3438. For more information, please visit http://live-strong.co/venus-factor/
News Article | August 29, 2016
Twenty papers in the special issue of the American Journal of Botany explore the evolutionary importance of polyploidy. Research presented in this issue highlights recent advances in old and new topics in the study of polyploidy. This image shows Crepis modocensis subsp. modocensis, Lake County, Oregon, United States. Crepis was among the first plant genera studied using biosystematic approaches, and the landmark monograph by Babcock and Stebbins (1938) established the genus as a model for research on asexual polyploids. Sears and Whitton (2016) revisit Crepis with contemporary data and largely find support for the classic results of Babcock and Stebbins (1938). Credit: Original unmodified image captured by Jeannette Whitton on a Canon PowerShot SX110 in July 2011. We might think of living organisms as typically having two sets of chromosomes—-one from mom and one from dad. But there are lots of variations out there. Polyploidy, or having more than two chromosome copies, is especially common in plants, including some of the tasty ones we eat, such as potatoes, wheat, and strawberries. In fact, polyploidy is a major driver of plant diversity both on our plates and in the wild. The resurgence in polyploidy research has followed the surprising result that many plant genomes are actually ancient polyploidy events. The American Journal of Botany Special Issue on "The Evolutionary Importance of Polyploidy" explores the latest developments and research in the field. Edited by Dr. Michael Barker (University of Arizona), along with Drs. Brian Husband (University of Guelph) and J. Chris Pires (University of Missouri), the collection gathers contributions that began as a symposium at the Botany 2015 meetings in Alberta, Canada. "We organized that symposium, and the issue, to highlight the recent renaissance of interest in polyploidy," says Dr. Barker. The special issue focuses on three main themes: polyploidy origins; evolutionary consequences; and impacts on plant ecology. The collection offers up-to-date reviews and modelling papers, together with comparative and in-depth studies from diverse polyploids. These articles shed light on questions of polyploidy old and new using both classical approaches and new techniques. Setting the foundations for both the special issue and future polyploidy work is a review by Soltis et al. (2016), who highlight what is known and the challenges of developing a unified theory of polyploidy. One immediate difficultly arising for a polyploid individual is finding suitable mates because of mismatches in genome number. Using modeling, Fowler and Levin (2016) show the importance of population size in polyploidy establishment, and phylogenetic analyses confirm polyploidy does often equal speciation (Zhan et al., 2016). However, speciation via polyploidy isn't entirely as simple as it sounds. Nuances of the mechanisms for reproductive isolation and speciation are explored further in the issue in two different species ((Husband et al., 2016; Vallejo-Marín et al., 2016). Unusual to most origin stories is that polyploids can do it more than once. Three groups trace the multiple independent origins of polyploidy showing how common it can be (McAllister and Miller, 2016; Rešetnik et al., 2016; Sears and Whitton, 2016). The consequences of genome duplication have important implications for how the genomes can evolve. Four papers explore the evolutionary consequences of polyploidy through literature review (Salse, 2016), a phylogenetic approach (Zenil-Ferguson et al., 2016), a laboratory study painting chromosomes (Mandáková et al., 2016), and a population genomic approach (Ågren et al., 2016) showing the diversity of methodologies taken to answering these questions. Other articles examine ancient polyploidy events to understand their consequences (Barker et al., 2016; Bergh et al., 2016), whereas a comparative approach suggests that there is a relationship between polyploidy and sexual system in plants (Glick et al., 2016). Although the evolutionary consequences of polyploidy are better studied, this collection highlights that genome duplications can have an impact on plant ecology. Segraves and Anneberg (2016) review the scant studies showing effects of polyploidy on plant interactions with pollinators, herbivores, and pathogens and suggest this is a rich avenue to explore. Stable environments may offer selection against polyploidization as suggested by an analysis of plants from the diverse flora of the South African Cape region (Oberlander et al., 2016), and two further studies show polyploids are associated with novel ecological niches (Arrigo et al., 2016; Laport et al., 2016). "A challenge for the community over the coming years will be to better integrate these disparate threads of research," said Barker. The way forward is to take an integrative approach. "Adding genetics and genomics to classically ecological study systems, or ecological and phenotypic analyses to well-studied genetic model systems will be a recipe for future success in polyploidy." Explore further: Genome duplication responsible for more plant species than previously thought More information: M. S. Barker et al, Spreading Winge and flying high: The evolutionary importance of polyploidy after a century of study, American Journal of Botany (2016). DOI: 10.3732/ajb.1600272
Evans M.,University of Manchester |
Lindsay J.,University of Guelph
Climate Research | Year: 2010
Over 50% of UK soil carbon is stored in peatland systems and 75% of these peatlands are upland blanket bog. The upland blanket bogs of the UK have suffered severe erosion over the last millennium so that they are widely dissected by gully systems. Gully erosion entails primary removal of particulate carbon from the peatland system but also has secondary effects in that it enhances drainage and lowers water tables, potentially enhancing decomposition of surface peats. This paper exploits recent high resolution mapping of the gully erosion on the Bleaklow Plateau in the southern Pennines and existing data on peat growth rates in the area to assess the impact of gully erosion on peatland carbon balance and the relative importance of primary and secondary impacts of gullying on carbon sequestration. The results indicate that gully erosion during the last millennium has shifted the Bleaklow Plateau from being a net sink of carbon (-20.3 gC m-2 yr-1) to a net source (29.4 gC m-2 yr-1). The relative importance of gullying impacts can be expressed as follows: particulate organic carbon (POC) flux > change in gully net ecosystem exchange ≫ loss of gully margin carbon sequestration. The implication of these findings is that the magnitude of the potentially reversible impacts of gully erosion (reduced carbon fixation due to vegetation loss and ongoing erosional loss of POC) far exceed the effects associated with irreversible morphological change (enhanced peat decomposition in gully margin locations). © Inter-Research 2010.
Luchman J.N.,Fors Marsh Group LLC |
Luchman J.N.,George Mason University |
Gonzalez-Morales M.G.,University of Guelph
Journal of Occupational Health Psychology | Year: 2013
The job demands-control-support model (DCS; Karasek, 1979) is an influential theory for understanding how work characteristics relate to employee well-being, health, and performance. However, previous research has largely neglected theory-building regarding the interrelationships between job demands, control, and support. We remedy such theoretical underdevelopment by reviewing and integrating theory on the relationships between demands, control, and support to develop five hypotheses. We test our hypotheses within a meta-analytic framework using a set of 106 studies. Our results show negative demands-supervisor support and demands-coworker support relationships, but no significant demand- control relationship. Our findings also indicate positive control-supervisor support and control- coworker support relationships. Using the meta-analytic effect sizes, we also estimate two competing structural equation models intended to discern which theoretical model using DCS work characteristics to predict occupational strain and well-being is more consistent with our data. Our results suggest that job control and both sources of social support should be treated independently, as opposed to indicators of a shared latent factor, in terms of their prediction of well-being and job demands. Our study offers support for the usefulness of the DCS and more modern conceptualizations of the working environment in understanding the employee work experience and for predicting important work outcomes. © 2013 American Psychological Association.
Turetsky M.R.,University of Guelph |
Kane E.S.,Michigan Technological University |
Harden J.W.,U.S. Geological Survey |
Ottmar R.D.,U.S. Department of Agriculture |
And 3 more authors.
Nature Geoscience | Year: 2011
Climate change has increased the area affected by forest fires each year in boreal North America. Increases in burned area and fire frequency are expected to stimulate boreal carbon losses. However, the impact of wildfires on carbon emissions is also affected by the severity of burning. How climate change influences the severity of biomass burning has proved difficult to assess. Here, we examined the depth of ground-layer combustion in 178 sites dominated by black spruce in Alaska, using data collected from 31 fire events between 1983 and 2005. We show that the depth of burning increased as the fire season progressed when the annual area burned was small. However, deep burning occurred throughout the fire season when the annual area burned was large. Depth of burning increased late in the fire season in upland forests, but not in peatland and permafrost sites. Simulations of wildfire-induced carbon losses from Alaskan black spruce stands over the past 60 years suggest that ground-layer combustion has accelerated regional carbon losses over the past decade, owing to increases in burn area and late-season burning. As a result, soils in these black spruce stands have become a net source of carbon to the atmosphere, with carbon emissions far exceeding decadal uptake. © 2011 Macmillan Publishers Limited. All rights reserved.
Hargreaves K.R.,University of Leicester |
Kropinski A.M.,Public Health Agency of Canada |
Kropinski A.M.,University of Guelph |
Clokie M.R.J.,University of Leicester
PLoS ONE | Year: 2014
The transfer of novel genetic material into the genomes of bacterial viruses (phages) has been widely documented in several host-phage systems. Bacterial genes are incorporated into the phage genome and, if retained, subsequently evolve within them. The expression of these phage genes can subvert or bolster bacterial processes, including altering bacterial pathogenicity. The phage phiCDHM1 infects Clostridium difficile, a pathogenic bacterium that causes nosocomial infections and is associated with antibiotic treatment. Genome sequencing and annotation of phiCDHM1 shows that despite being closely related to other C. difficile myoviruses, it has several genes that have not been previously reported in any phage genomes. Notably, these include three homologs of bacterial genes from the accessory gene regulator (agr) quorum sensing (QS) system. These are; a pre-peptide (AgrD) of an autoinducing peptide (AIP), an enzyme which processes the pre-peptide (AgrB) and a histidine kinase (AgrC) that detects the AIP to activate a response regulator. Phylogenetic analysis of the phage and C. difficile agr genes revealed that there are three types of agr loci in this species. We propose that the phage genes belonging to a third type, agr3, and have been horizontally transferred from the host. AgrB and AgrC are transcribed during the infection of two different strains. In addition, the phage agrC appears not to be confined to the phiCDHM1 genome as it was detected in genetically distinct C. difficile strains. The discovery of QS gene homologs in a phage genome presents a novel way in which phages could influence their bacterial hosts, or neighbouring bacterial populations. This is the first time that these QS genes have been reported in a phage genome and their distribution both in C. difficile and phage genomes suggests that the agr3 locus undergoes horizontal gene transfer within this species. © 2014 Hargreaves et al.
Chen P.X.,University of Guelph |
Wang S.,University of Guelph |
Nie S.,Nanchang University |
Marcone M.,University of Guelph
Journal of Functional Foods | Year: 2013
A great mystique and aura surrounds Cordyceps sinensis (syn.: Cephalosporium sinensis), an endoparasitic fungus which has claims of anti-cancer and anti-aging properties. Much research has been conducted over the years on crude extracts and its bioactivity. More research is now focused on culturing C. sinensis and on isolating and identifying pure compounds novel to C. sinensis in an attempt to alleviate strain on demand for the natural fungi. Several polysaccharides, nucleosides and sterols all have had reports of promoting health both in vitro and in vivo. Specific and novel compounds which are characteristic to C. sinensis are emerging with reports of two new epipolythiodioxopiperazines, gliocladicillins A and B capable of inhibiting growth of HeLa, HepG2 and MCF-7 tumor cells. Exclusive to natural C. sinensis, five constituents of cordysinin (A-E) has also been reported for the first time and has been linked to anti-inflammatory properties. Although it may still be premature to believe these results should translate into pharmaceutical use, there is sufficient evidence to warrant further research. © 2013.
Steelman C.M.,University of Waterloo |
Steelman C.M.,University of Guelph |
Endres A.L.,University of Waterloo
Journal of Hydrology | Year: 2012
Soil moisture measurement techniques are of utmost importance to vadose zone hydrologists. Surface hydrogeophysical methods, such as ground-penetrating radar (GPR), have the capacity to provide field-scale soil moisture information across a range of depth scales. This paper presents an extensive field study using multi-frequency (i.e., 225. MHz, 450. MHz, 900. MHz) GPR common-midpoint (CMP) soundings to monitor a complete annual cycle of soil moisture conditions at three distinct sites. We examine the use of normal-moveout (NMO) velocity analysis applied to CMP data for monitoring highly dynamic vertical soil moisture conditions in a mid-latitude climate consisting of wetting/drying and freeze/thaw cycles with varying degrees of magnitude and vertical velocity gradient. NMO velocity analysis is used to construct interval-velocity-depth models at a fixed location collected every 1-4. weeks. These time-lapse models are combined to construct temporal interval-velocity fields, which are converted into soil moisture content using an appropriate petrophysical relationship. Using these moisture fields, we were able to characterize the vertical distribution and dynamics of soil moisture in the shallow vadose zone. Although the use of multiple antenna frequencies provided varying investigation depths and vertical resolving capabilities, optimal characterization of soil moisture conditions was obtained with high-frequency 900. MHz antennas. The integration of direct ground wave and NMO velocity data from a single CMP sounding allowed us to better refine the shallow soil moisture profile and underlying vadose zone conditions during seasonal wetting, drying and freezing cycles. This study demonstrates the capacity of GPR to characterize vertical moisture dynamics, and highlights the importance of collecting high-resolution data along the air-soil interface to resolve the water content profile from the surface down to the deeper vadose zone conditions. © 2012 Elsevier B.V.
Pfohl-Leszkowicz A.,CNRS Chemical Engineering Laboratory |
Manderville R.A.,University of Guelph
Chemical Research in Toxicology | Year: 2012
Ochratoxin A (OTA) is a naturally occurring chlorophenolic fungal toxin that contaminates a wide range of food products and poses a cancer threat to humans. The mechanism of action (MOA) for OTA renal carcinogenicity is a controversial issue. In 2005, direct genotoxicity (covalent DNA adduct formation) was proposed as a MOA for OTA-mediated carcinogenicity [Manderville, R. A. (2005) Chem. Res. Toxicol. 18, 1091 - 1097]. At that time, inconsistent results had been published on OTA genotoxicity/mutagenicity, and conclusive evidence for OTA-mediated DNA adduction had been lacking. In this update, published data from the past 6 - 7 years are presented that provide new hypotheses for the MOA (Figure presented) of OTA-mediated carcinogenicity. While direct genotoxicity remains a controversial issue for OTA, new findings from the Umemura and Nohmi laboratories provide definitive results for the mutagenicity of OTA in the target tissue (outer medulla) of male rat kidney that rules out oxidative DNA damage. These findings, coupled with our own efforts that provide new structural evidence for DNA adduction by OTA, has strengthened the argument for involvement of direct genotoxicity in OTA-mediated renal carcinogenesis. This MOA should be taken into consideration for OTA human risk assessment. © 2011 American Chemical Society.
Karmali M.A.,Public Health Agency of Canada |
Gannon V.,Public Health Agency of Canada |
Sargeant J.M.,University of Guelph
Veterinary Microbiology | Year: 2010
Escherichia coli O157:H7 and other Verocytotoxin-producing E. coli (VTEC) are zoonotic pathogens associated with food and waterborne illness around the world. E. coli O157:H7 has been implicated in large outbreaks as well as in sporadic cases of haemorrhagic colitis and the sometimes fatal haemolytic uremic syndrome. VTs produced by these bacteria are thought to damage host endothelial cells in small vessels of the intestine, kidney and brain resulting in thrombotic microangiopathy. All VTs have the same subunit structure, glycolipid cell receptor and inhibit protein synthesis. During VTEC infection, it is thought one or more bacterial adhesins initiates colonization and establishes intimate attachment and is responsible for the translocation of a variety of effectors which alter the structure and function of host cells. VTEC are widespread in animals but ruminants are thought to be their natural reservoir. E. coli O157:H7 colonizes the terminal colon of cattle and can be shed in very large numbers by specific herdmates known as "supershedders". Faeces containing these organisms act as a source of contamination for a variety of foods and the environment. Many VTEC control efforts have been investigated along the "farm to fork" continuum including, vaccination of cattle with colonization factors, and the use of novel antimicrobials, such as bacteriocins, chloral hydrate, bacteriophage and substances which disrupt quorum sensing. In addition, many barriers have been developed for use in the slaughter and food processing industry such as steam pasteurization and irradiation. Despite these efforts many scientific, technical and regulatory challenges remain in the control and prevention of VTEC-associated human illness. © 2009 Elsevier B.V. All rights reserved.
Keller H.H.,University of Waterloo |
Duizer L.M.,University of Guelph
Journal of Nutrition in Gerontology and Geriatrics | Year: 2014
This qualitative study is based on in-depth interviews with 15 consumers (+4 family members) of pureed food. Transcripts were thematically analyzed to summarize and interpret these data. Although no consumer enjoyed eating pureed food, some were grateful to be able to be nourished orally. Food was described as being poor in terms of sensory appeal, and products were often indistinguishable from each other. Consistency in production, delivery, and approach to presentation was identified to be a challenge that affected the acceptance of products, and variety was often lacking. However, consumers saw the necessity of the texture and provided several suggestions that are practicable and feasible for improving their experience and "making the best of it." This is the first in-depth study on consumer perception of pureed food. It not only provides insights into their experience and the impacts on their quality of life but also provides information about ways providers can improve upon these products. © 2014 Copyright Taylor & Francis Group, LLC.
Evans M.,University of Manchester |
Lindsay J.,University of Guelph
Earth Surface Processes and Landforms | Year: 2010
The upland peatlands of the UK are severely eroded, with large areas affected by gully erosion. The peatlands are important areas of carbon storage and provide a range of other ecosystem services including water supply and biodiversity all of which are negatively impacted by erosion of the upland surface. The magnitude of the gully erosion, and consequent adjustment of the peatland morphology, is such that in degraded peatlands the extent and magnitude of erosion is a major control on peatland function. Accurate mapping of gully form is therefore a necessary precondition to the understanding and management of these systems. This paper develops an approach to extracting gully maps from high resolution digital elevation models (DEMs). Gully maps of the Bleaklow Plateau in northern England were derived from a 2 m LiDAR DEM by combining areas of low difference from mean elevation and high positive plan curvature. Gully depth was modelled by interpolating between gully edges. Testing of the gully mapping and depth modelling against aerial photography, manual interpretation of the DEM and ground survey revealed that gully plan form is well represented and gully width and depth are modelled with tolerances close to the horizontal and vertical resolution of the LiDAR imagery. Estimates of gully width and depth were less reliable for gullies with total width of less than four pixels. The approach allows for the first time the derivation of accurate estimates of gully extent and magnitude over large areas and provides the basis for modelling a range of processes controlled by gullying. The approach has wider appli- cability to mapping gully erosion in a wide range of environments. © 2010 John Wiley & Sons, Ltd.
Soliman S.S.M.,University of Guelph |
Soliman S.S.M.,Zagazig University |
Raizada M.N.,University of Guelph
Frontiers in Microbiology | Year: 2013
Within a plant, there can exist an ecosystem of pathogens and endophytes, the latter described as bacterial and fungal inhabitants that thrive without causing disease to the host. Interactions between microbial inhabitants represent a novel area of study for natural products research. Here we analyzed the interactions between the fungal endophytes of Taxus (yew) trees. Fungal endophytes of Taxus have been proposed to produce the terpenoid secondary metabolite, Taxol, an anti-cancer drug. It is widely reported that plant extracts stimulate endophytic fungalTaxol production, but the underlying mechanism is not understood. Here,Taxus bark extracts stimulated fungalTaxol production 30-fold compared to a 10-fold induction with wood extracts. However, candidate plant-derived defense compounds (i.e., salicylic acid, benzoic acid) were found to act only as modest elicitors of fungal Taxol production from the endophytic fungus Paraconiothyrium SSM001, consistent with previous studies. We hypothesized the Taxus plant extracts may contain elicitors derived from other microbes inhabiting these tissues. We investigated the effects of co-culturing SSM001 with other fungi observed to inhabit Taxus bark, but not wood. Surprisingly, co-culture of SSM001 with a bark fungus (Alternaria) caused a ~threefold increase in Taxol production. When SSM001 was pyramided with both the Alternaria endophyte along with another fungus (Phomopsis) observed to inhabit Taxus, there was an ~eightfold increase in fungal Taxol production from SSM001. These results suggest that resident fungi within a host plant interact with one another to stimulate Taxol biosynthesis, either directly or through their metabolites. More generally, our results suggest that endophyte secondary metabolism should be studied in the context of its native ecosystem. © 2013 Soliman and Raizada.
Schmidt S.,University of Waterloo |
Monk J.M.,University of Guelph |
Robinson L.E.,University of Guelph |
Mourtzakis M.,University of Waterloo
Obesity Reviews | Year: 2015
Obesity is an established risk factor for postmenopausal breast cancer. The mechanisms through which obesity influences the development and progression of breast cancer are not fully elucidated; however, several factors such as increased oestrogen, concentrations of various members of the insulin family and inflammation that are associated with adiposity are purported to be important factors in this relationship. Emerging research has also begun to focus on the role of adipokines, (i.e. adipocyte secreted factors), in breast cancer. Leptin secretion is directly related to adiposity and is believed to promote breast cancer directly and independently, as well as through involvement with the oestrogen and insulin signalling pathways. As leptin is secreted from white adipose tissue, any intervention that reduces adiposity may be favourable. However, it is also important to consider that energy expenditure through exercise, independent of fat loss, may improve leptin regulation. The purpose of this narrative review was to explore the role of leptin in breast cancer development and progression, identify key interactions with oestrogen and the insulin family, and distinguish the potential effects of exercise on these interactions. © 2015 The Authors.
Oraby T.,University of Guelph |
Oraby T.,University of Waterloo
Proceedings. Biological sciences / The Royal Society | Year: 2014
Mathematical models that couple disease dynamics and vaccinating behaviour often assume that the incentive to vaccinate disappears if disease prevalence is zero. Hence, they predict that vaccine refusal should be the rule, and elimination should be difficult or impossible. In reality, countries with non-mandatory vaccination policies have usually been able to maintain elimination or very low incidence of paediatric infectious diseases for long periods of time. Here, we show that including injunctive social norms can reconcile such behaviour-incidence models to observations. Adding social norms to a coupled behaviour-incidence model enables the model to better explain pertussis vaccine uptake and disease dynamics in the UK from 1967 to 2010, in both the vaccine-scare years and the years of high vaccine coverage. The model also illustrates how a vaccine scare can perpetuate suboptimal vaccine coverage long after perceived risk has returned to baseline, pre-vaccine-scare levels. However, at other model parameter values, social norms can perpetuate depressed vaccine coverage during a vaccine scare well beyond the time when the population's baseline vaccine risk perception returns to pre-scare levels. Social norms can strongly suppress vaccine uptake despite frequent outbreaks, as observed in some small communities. Significant portions of the parameter space also exhibit bistability, meaning long-term outcomes depend on the initial conditions. Depending on the context, social norms can either support or hinder immunization goals.
Kaltenbaek R.,University of Waterloo |
Lavoie J.,University of Waterloo |
Zeng B.,University of Waterloo |
Zeng B.,University of Guelph |
And 2 more authors.
Nature Physics | Year: 2010
One-way quantum computation proceeds by sequentially measuring individual spins in an entangled many-spin resource state1. It remains a challenge, however, to efficiently produce such resources. Is it possible to reduce the task of their production to simply cooling a quantum many-body system to its ground state? Cluster states, the canonical resource for one-way quantum computing, do not naturally occur as ground states of physical systems 2,3, leading to a significant effort to identify alternatives that do appear as ground states in spin lattices4-8. An appealing candidate is a valence-bondsolid state described by Affleck, Kennedy, Lieb and Tasaki 9 (AKLT). It is the unique, gapped ground state for a two-body Hamiltonian on a spin-1 chain, and can be used as a resource for one-way quantum computing4-7. Here, we experimentally generate a photonic AKLT state and use it to implement singlequbit quantum logic gates. © 2010 Macmillan Publishers Limited. All rights reserved.
Gregory S.G.,University of Exeter |
Jardine M.,University of St. Andrews |
Gray C.G.,University of Guelph |
Donati J.-F.,French National Center for Scientific Research
Reports on Progress in Physics | Year: 2010
Magnetic fields play a crucial role at all stages of the formation of low-mass stars and planetary systems. In the final stages, in particular, they control the kinematics of in-falling gas from circumstellar discs, and the launching and collimation of spectacular outflows. The magnetic coupling with the disc is thought to influence the rotational evolution of the star, while magnetized stellar winds control the braking of more evolved stars and may influence the migration of planets. Magnetic reconnection events trigger energetic flares which irradiate circumstellar discs with high energy particles that influence the disc chemistry and set the initial conditions for planet formation. However, it is only in the past few years that the current generation of optical spectropolarimeters has allowed the magnetic fields of forming solar-like stars to be probed in unprecedented detail. In order to do justice to the recent extensive observational programs new theoretical models are being developed that incorporate magnetic fields with an observed degree of complexity. In this review we draw together disparate results from the classical electromagnetism, molecular physics/chemistry and the geophysics literature, and demonstrate how they can be adapted to construct models of the large scale magnetospheres of stars and planets. We conclude by examining how the incorporation of multipolar magnetic fields into new theoretical models will drive future progress in the field through the elucidation of several observational conundrums. © 2010 IOP Publishing Ltd.
Barausse E.,University of Guelph |
Barausse E.,University of Maryland University College
Monthly Notices of the Royal Astronomical Society | Year: 2012
Future space-based gravitational-wave detectors, such as the Laser Interferometer Space Antenna (LISA/SGO) or a similar European mission (eLISA/NGO), will measure the masses and spins of massive black holes up to very high redshift, and in principle discriminate among different models for their evolution. Because the masses and spins change as a result of both accretion from the interstellar medium and the black hole mergers that are expected to naturally occur in the hierarchical formation of galaxies, their evolution is inextricably entangled with that of their galactic hosts. On the one hand, the amount of gas present in galactic nuclei regulates the changes in the black hole masses and spins through accretion, and affects the mutual orientation of the spins before mergers by exerting gravitomagnetic torques on them. On the other hand, massive black holes play a central role in galaxy formation because of the feedback exerted by active galactic nuclei on the growth of structures. In this paper, we study the mass and spin evolution of massive black holes within a semi-analytical galaxy-formation model that follows the evolution of dark-matter haloes along merger trees, as well as that of the baryonic components (hot gas, stellar and gaseous bulges, and stellar and gaseous galactic discs). This allows us to study the mass and spin evolution in a self-consistent way, by taking into account the effect of the gas present in galactic nuclei both during the accretion phases and during mergers. Also, we present predictions, as a function of redshift, for the fraction of gas-rich black hole mergers - in which the spins prior to the merger are aligned due to the gravitomagnetic torques exerted by the circumbinary disc - as opposed to gas-poor mergers, in which the orientation of the spins before the merger is roughly isotropic. These predictions may be tested by LISA or similar spaced-based gravitational-wave detectors such as eLISA/NGO or SGO. © 2012 The Author. Monthly Notices of the Royal Astronomical Society © 2012 RAS.
Ostrowski J.,University of Waterloo |
Anjos M.F.,University of Waterloo |
Vannelli A.,University of Guelph
IEEE Transactions on Power Systems | Year: 2012
This paper examines the polytope of feasible power generation schedules in the unit commitment (UC) problem. We provide computational results comparing formulations for the UC problem commonly found in the literature. We introduce a new class of inequalities, giving a tighter description of feasible operating schedules for generators. Computational results show that these inequalities can significantly reduce overall solution times. © 2006 IEEE.
University of Guelph and Beth Israel Deaconess Medical Center | Date: 2014-03-11
The invention features thrombospondin-1 (TSP-1) polypeptides (e.g., 3TSR-Fc fusion proteins), nucleic acid molecules encoding the TSP-1 polypeptides, and compositions thereof. The invention also features methods of making and using the TSP-1 polypeptides of the invention (e.g., using 3TSR-Fc fusion proteins to treat a subject having a disorder associated with pathological angiogenesis, e.g., cancer, e.g., epithelial ovarian cancer (EOC)).
Beth Israel Deaconess Medical Center and University of Guelph | Date: 2016-03-01
The invention features thrombospondin-1 (TSP-1) polypeptides (e.g., 3TSR-Fc fusion proteins), nucleic acid molecules encoding the TSP-1 polypeptides, and compositions thereof. The invention also features methods of making and using the TSP-1 polypeptides of the invention (e.g., using 3TSR-Fc fusion proteins to treat a subject having a disorder associated with pathological angiogenesis, e.g., cancer, e.g., epithelial ovarian cancer (EOC)).
Pries F.,University of Guelph |
Guild P.,University of Waterloo
Technovation | Year: 2011
One of the key challenges in commercializing inventions arising from academic research is deciding on an appropriate business model for transferring the invention from the academic world to the commercial world. However, there is little empirical evidence to suggest which model to choose. This study attempts to address this gap by examining how characteristics of technologies affect the selection of business models. We consider four characteristics of technology: patent or other legal protection, specialized complementary assets, commercial uncertainty and technological dynamism. We relate these characteristics to the choice of three basic business models for commercializing inventions. Data for this study were gathered for 42 commercialized inventions. We found evidence that greater patent or other legal protection for the technology was associated with a greater likelihood that the technology was commercialized by transferring limited rights to the technology to existing firms. We also found evidence that greater commercial uncertainty was associated with a greater likelihood that the technology was commercialized by creation of a new firm or transfer of the rights to the technology to an existing firm. We did not find evidence of a relationship between the importance of specialized complementary assets or technological dynamism and the business model used. © 2010 Elsevier Ltd.
News Article | November 10, 2016
TORONTO, ON--(Marketwired - November 10, 2016) - The Magazine Grands Prix are proud to present author, commentator and critic Stanley Péan and award-winning writer Soraya Peerbaye as judging co-chairs for the new award and fellowship program that celebrates the diversity of the country's magazine media. "We are building a robust, transparent awards program that we can be proud of: right from the ground up," said Matthew Holmes, Magazines Canada's President and CEO. "With Canada's 150th being celebrated next year, we wanted to look forward and make a very intentional shift to include the full diversity of Canada's creators and -- just as important -- our community of readers, right into our judging process." Magazines Canada announced the awards and fellowship program in September. They will feature 26 categories: 13 awards for individuals and creators, and 13 for magazines that honour creative and editorial vision and execution. "Stanley Péan and I are honoured and immensely pleased to be co-chairing the adjudication process of the Magazine Grands Prix," said Peerbaye. "The team at Magazines Canada has developed a far-seeing vision for the awards; energetic and generous, they are broadening the circle of inclusion, and invigorating the conversation on both popular and critical culture in the magazine sector." With input and advice from judging co-chairs Péan and Peerbaye, the Magazine Grands Prix judging process will reflect an ambitious set of guiding principles, released today on the official awards website, maggrandsprix.ca. The document, "Guiding Principles for Adjudicating and Celebrating Excellence in Canada's Magazine Media," reflects the following aspirations and targets: To build and execute an awards program that showcases the sector's full range and excellence: seamlessly bilingual in English and French, reflective of Canada's diversity, and open to all; To represent a diversity of artistic and cultural practices, perspectives and expertise on all juries, valuing the magazine sector's creators and the public equally. Juries will be composed to reflect the diversity of Canada with regard to Indigenous peoples, race, regions, official languages, and gender; To have Indigenous jurists on the majority of the panels. This is just the beginning. The goal is to have Indigenous jurists on every single panel; To compose juries with care for plurality: no jury in which there is only one non-white jurist, and many in which there is a variety of diverse representatives. All jurists must feel able to speak freely and judge the submissions on their merits, without any obligation to represent minority or identity-based views; To reveal our entire roster of jurists during the submissions period: underrepresented communities must see themselves reflected and welcomed in order to participate fully; To aspire to do better than simply meeting the principles outlined and, in instances where we fall short of these goals, to recognize it and take action to improve. As part of this commitment to transparency and continuous improvement, the Magazine Grands Prix also pledge to provide an avenue for feedback and input into their processes and decisions. They invite the public to engage and share ideas on how to improve the awards by writing to them at email@example.com. Submissions open: December 12, 2016 Submissions close: January 30, 2017 Awards fête: April 27, 2017, in conjunction with Magazine Canada's annual MagNet conference, North America's largest annual gathering of magazine professionals. For more on the awards, visit maggrandsprix.ca. About Stanley Péan Stanley Péan was born in Port-au-Prince, Haiti and grew up in Jonquière, Québèc. He is the author of more than twenty books for adults and adolescents and wears many other hats: radio host, TV personality, translator, scriptwriter, journalist and former editor-in-chief of Le Libraire, the bi-monthly publication of a network of independent bookstores in Québéc. From 2004 to 2010, Péan was chairman of the l'Union des écrivaines et écrivains québécois (UNEQ), the association that advocates for writers and promotes their work. His collection of stories, Autochtones de la nuit (2007), was the third book of the trilogy that included La nuit démasque (2000) and Le cabinet du Docteur K (2001); the earlier books were re-released as paperbacks along with the novels Le Tumulte de mon sang (1991) and Zombi Blues (1996). During the same period as the release of the Italian translation by publisher Tropea Editore, Péan marked his return to the novel with Bizango (2011). About Soraya Peerbaye Soraya Peerbaye's most recent collection of poetry, Tell: Poems for a Girlhood (Pedlar Press, 2015), won the Trillium Book Award for Poetry in English and was a finalist for the Griffin Poetry prize. Her first collection, Poems for the Advisory Committee on Antarctic Names (Goose Lane Editions, 2009) was short-listed for the Gerald Lampert Award. Her poems have appeared in Red Silk: An Anthology of South Asian Women Poets, and the chapbook anthology Translating Horses. She holds an MFA in Creative Writing from the University of Guelph. For over a decade, Soraya worked in program and policy development and management, first as the Equity Coordinator at the Canada Council for the Arts, then as a grants officer at the Toronto Arts Council, where she oversaw adjudications in performing arts and strategic initiatives. She remains active as a consultant, curator and collaborator in national initiatives that center on equity, decolonization and intersectionality in the arts. About the Magazine Grands Prix Starting in 2017, a bold new awards program will celebrate the best of Canada's magazine media. From the most dog-eared pages to the best in multi-media content, the Canadian Magazine Awards will showcase the sector's range and excellence. Submissions are welcome from all Canadian magazines: large and small, niche, specialty and general interest, local, regional and national. The Magazine Grands Prix include 26 categories: 13 awards for individuals and creators, and 13 for magazines which honour creative and editorial vision and execution. The top two awards will recognize the editor of the year with the "Editor Grand Prix" and the magazine of the year with the "Magazine Grand Prix." Award categories are open to submissions from any platform and extend to new media applications, including videography, motion graphics and multi-platform treatment. Eligible magazines must maintain at least two print editions each year. The Magazine Grands Prix will also present a series of fellowships to Canadian journalists working on stories that explore in depth the issues that are most important to Canadians. About Magazines Canada Magazines Canada is the national association representing the majority of Canadian-owned, Canadian-content consumer, cultural, specialty, professional and business magazines. French and English member titles cover a wide range of interests across multiple platforms including arts and culture, business and professional, lifestyle and food, news and politics, sports and leisure, women and youth. The association focuses on government affairs, professional development, coordinating national awards programs and marketing campaigns, and delivering services that meet the needs of the magazine industry. Visit magazinescanada.ca.
News Article | September 22, 2016
University of Guelph researchers studying the intimate structure of edible fats are getting help from the United States Department of Energy (DOE). The researchers hope to replace unhealthful trans and saturated fats with better non-saturated versions – all without compromising texture. That swap could have great implications for the food industry, says Maria Fernanda Peyronel-Svaikauskas, a research associate working with food scientist Alejandro Marangoni. To conduct their studies, Peyronel-Svaikauskas and the other U of G researchers use the DOE’s Advanced Photon Source (APS) at Argonne National Laboratory in Lemont, Illinois. X-rays generated at that facility enable scientists to study and characterize the structure of edible fats at meso and micro levels (hundreds of nanometers to a few micrometers in size). Edible fats are made of triglycerides that clump to form crystalline nanoplatelets (CNPs), which in turn form larger masses of particles. The researchers use the APS to study those larger structures inside and out. Unlike using conventional microscopy, using X-rays means researchers need not condition or manipulate samples for in-situ measurement. Peyronel-Svaikauskas says trans and saturated fats are important because they provide structure for semi-solid edible fats such as shortening or butter-like spreads. But “as soon as the healthier unsaturated fats are used to replace the trans and saturated ones, the solid structure is lost,” she says. “The key problem is the food industry trying to do this with much trial and error. We are trying to help them with our research by removing the trial and error.” Researchers have looked at fats using other sophisticated imaging techniques for decades. The Guelph team uses new technology at the APS called ultra-small angle X-ray scattering for the first such structural analysis of fats and oils. The researchers model CNPs in computer simulations to guide experiments and predict outcomes. Researchers need to propose experiments and book APS time through the DOE. Peyronel-Svaikauskas says they need to be ready to go to Illinois and squeeze a lot of work into eight-hour shifts, all in a high-security facility. “You feel like you don’t want to touch anything, and every step you take, there is someone telling you what or what not to do. You’re always concerned that you’re going to press the wrong button or that the alarm will sound. It’s tense.” Radiation is a concern when working with X-rays, but she says researchers can accomplish a lot using the high-flux, high-energy X-ray beams at the APS. “You’re looking at X-ray scattering at really tiny angles. The smaller the angle, the larger the feature you look at in your sample. That’s important if you want to understand how the meso to micro structure gets formed.” They found characteristic patterns normally missed by conventional wide- or small-angle scattering. Their computer models and predictions helped them understand what was happening to fat structures. Food scientists may use this information to decide whether they have the desired product for a particular purpose, such as a spreading or a fat to make cookies or to get the best chocolate. “When you think about the amount of applications for fat, it’s tremendous,” says Peyronel-Svaikauskas. “It’s hard to say that what you see in one system can be translated to another system because you are talking about different molecules, and each one has to be processed according to the functionality you want at the end.” By understanding the structure of unhealthful fats, she hopes to advise industry when substituting an unsaturated fat for a saturated one. The U of G researchers also plan to look at the effects of enzymes on their samples.
Pokhrel L.R.,East Tennessee State University |
Dubey B.,University of Guelph
Critical Reviews in Environmental Science and Technology | Year: 2013
With rising valuation of mineral commodities, mining has been envisioned as a profitable industry regardless of many challenges it entails. This comprehensive review provides the state of knowledge about several aspects of the metal mining industry, including (a) the basic mining processes with reasons for mine closure, (b) the potential environmental and human health impacts associated with mining, (c) the potential techniques for impact mitigation, (d) the latest production statistics for the base and precious metals with identification of currently operational major metal mines for different countries, and (e) how mining activities are regulated in different nations. Finally, the authors provide critical appraisal on the debatable issue of mining and sustainability to stimulate thoughts on how metal mining can be made sustainable, and suggest a path forward. © 2013 Copyright Taylor and Francis Group, LLC.
Chen H.,U.S. Department of Agriculture |
Yada R.,University of Guelph
Trends in Food Science and Technology | Year: 2011
Nanoscale science and nanotechnology have been demonstrated to have great potential in providing novel and improved solutions to many grand challenges facing agriculture and society today and in the future. This review highlights some of the most promising and important nanotechnology applications in agriculture; and recommends several strategies for advancing the best scientific and technological knowledge presently being examined. In addition, implications for human and environmental health, and technical, financial and capacity-related challenges as they relate to developing countries are identified. Finally, some suggested mechanisms for partnerships and collaborations are also identified and suggested. © 2011.
Pokhrel L.R.,East Tennessee State University |
Dubey B.,University of Guelph
Science of the Total Environment | Year: 2013
The increasing applications of different nanomaterials in the myriad of nano-enabled products and their potential for leaching have raised considerable environmental, health and safety (EHS) concerns. As systematic studies investigating potential anomalies in the morphology and anatomy of crop plants are scarce, herein we report on the developmental responses of two agriculturally significant crop plants, maize (Zea mays L.) and cabbage (Brassica oleracea var. capitata L.), upon in vitro exposure to nanoparticles of citrate-coated silver (Citrate-nAg) and zinc oxide (nZnO). Analyses involve histology of the primary root morphology and anatomy using light microscopy, metal biouptake, moisture content, rate of germination, and root elongation. Comparative toxicity profiles of the ionic salts (AgNO3 and ZnSO4) are developed. Notably, we uncover structural changes in maize primary root cells upon exposure to Citrate-nAg, nZnO, AgNO3, and ZnSO4, possibly due to metal biouptake, suggesting potential for functional impairments in the plant growth and development. Citrate-nAg exposure results in lower Ag biouptake compared to AgNO3 treatment in maize. Microscopic evidence reveals 'tunneling-like effect' with nZnO treatment, while exposure to AgNO3 leads to cell erosion in maize root apical meristem. In maize, a significant change in metaxylem count is evident with Citrate-nAg, AgNO3, and ZnSO4 treatment, but not with nZnO treatment (p>0.1). In both maize and cabbage, measures of germination and root elongation reveal lower nanoparticle toxicity compared to free ions. As moisture data do not support osmotically-induced water stress hypothesis for explaining toxicity, we discuss other proximate mechanisms including the potential role of growth hormones and transcription factors. These findings highlight previously overlooked, anatomically significant effects of metal nanoparticles, and recommend considering detailed anatomical investigations in tandem with the standard developmental phytotoxicity assays (germination and root elongation) as the latter ones appear less sensitive for screening plant responses to nanomaterial insults. © 2013 Elsevier B.V.
Lehner L.,Perimeter Institute for Theoretical Physics |
Lehner L.,University of Guelph |
Lehner L.,Canadian Institute for Advanced Research CIFAR |
Pretorius F.,Princeton University
Physical Review Letters | Year: 2010
We describe the behavior of 5-dimensional black strings, subject to the Gregory-Laflamme instability. Beyond the linear level, the evolving strings exhibit a rich dynamics, where at intermediate stages the horizon can be described as a sequence of 3-dimensional spherical black holes joined by black string segments. These segments are themselves subject to a Gregory-Laflamme instability, resulting in a self-similar cascade, where ever-smaller satellite black holes form connected by ever-thinner string segments. This behavior is akin to satellite formation in low-viscosity fluid streams subject to the Rayleigh-Plateau instability. The simulation results imply that the string segments will reach zero radius in finite asymptotic time, whence the classical space-time terminates in a naked singularity. Since no fine-tuning is required to excite the instability, this constitutes a generic violation of cosmic censorship.
Casals M.,Perimeter Institute for Theoretical Physics |
Casals M.,University of Guelph |
Casals M.,University College Dublin |
Ottewill A.,University College Dublin
Physical Review Letters | Year: 2012
Linear field perturbations of a black hole are described by the Green function of the wave equation that they obey. After Fourier decomposing the Green function, its two natural contributions are given by poles (quasinormal modes) and a largely unexplored branch cut in the complex frequency plane. We present new analytic methods for calculating the branch cut on a Schwarzschild black hole for arbitrary values of the frequency. The branch cut yields a power-law tail decay for late times in the response of a black hole to an initial perturbation. We determine explicitly the first three orders in the power-law and show that the branch cut also yields a new logarithmic behavior TT for late times. Before the tail sets in, the quasinormal modes dominate the black hole response. For electromagnetic perturbations, the quasinormal mode frequencies approach the branch cut at large overtone index n. We determine these frequencies up to n -5 /2 and, formally, to arbitrary order. Highly damped quasinormal modes are of particular interest in that they have been linked to quantum properties of black holes. © 2012 American Physical Society.
Acevedo N.C.,Iowa State University |
Block J.M.,Federal University of Santa Catarina |
Marangoni A.G.,University of Guelph
Langmuir | Year: 2012
The effects of processing using a scraped surface heat exchanger (SSHE) before and after adding unsaturated monoglyceride (UM) on blends of fully hydrogenated soybean oil (FHSO) and soybean oil (SO) were studied. Mixtures of 40:60 and 45:55 FHSO:SO were melted at 80 °C for 30 min and crystallized statically or in the SSHE (shear rate of 25 s-1) at a cooling rate of 9 °C/min. Upon shearing and UM addition, polymorphic transformations toward more (β) or less (β') stable forms were governed by the combination between system concentration, composition, and crystallization conditions, as determined by differential scanning calorimetry and powder X-ray diffraction. Nuclear magnetic resonance was used to measure the solid fat content (SFC) development which showed to increase with processing conditions due to the high nucleation rate induced. Processing conditions greatly affected the nano- and microcrystalline structures which were characterized by polarized light microscopy (PLM), cryogenic transmission electron microscopy (Cryo- TEM), and Scherrer analysis of the powder X-ray diffraction data. Crystallization under shear promoted the longitudinal growth of the nanoplatelets; nevertheless, meso structural elements showed a decrease in their dimensions under the same crystallization conditions. The relative oil loss determined gravimetrically was inversely related to the elastic modulus and yield stress of the sheared fat blends, and values were closer to the desirable usability ranges for bakery applications. Our results suggest that fully hydrogenated fats can be functionalized by crystallization in a SSHE and/or by judicious addition of an unsaturated emulsifier. © 2012 American Chemical Society.
Xiang Y.,University of Guelph |
Chen J.,University of Guelph |
Deshmukh A.,University of Massachusetts Amherst
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014
We propose a decision-theoretic graphical model for collaborative design in a supply chain. The graphical model encodes the uncertain performance of a product resultant from an integrated design distributively. It represents preference of multiple manufacturers and endusers such that a decision-theoretic design is well-defined. We show that these distributed design information can be represented in a multiply sectioned Bayesian network. This result places collaborative design in a formal framework so that it can be subject to rigorous algorithmic study. © Springer-Verlag Berlin Heidelberg 2004.
Gillies J.A.,Desert Research Institute |
Nickling W.G.,University of Guelph |
Tilson M.,University of Guelph
Journal of Geophysical Research: Earth Surface | Year: 2013
Due, in part, to the challenging environment of Earth's high-latitude regions, available information on cold climate effects on aeolian processes in these areas remains limited. Data from these areas, however, provide insight into the physics of sediment transport by wind and the controls on erosive winds in proximity to ice caps and topographic influences. This study presents a 2 year record of meteorological, saltation activity, horizontal saltation flux, and particle size distribution data from four sites in the McMurdo Dry Valleys of Antarctica, 2008 to 2010. Saltation measurements revealed daily and seasonal patterns with spring and summer sediment transport events occurring between 09:00 and 24:00 hours due to thermally generated winds. Fall and winter events occur at any time of day with the strongest associated with foehn winds. Threshold wind speed at 4.2 m in all seasons for all locations was ≈10 m s-1. Saltation occurred in the temperature range -40°C to +5°C. Westerly winds in the fall/winter and easterly winds in spring/summer are associated with the majority of transport events. The sand in transport is mainly 250 to 500 μm in diameter and poorly sorted. The integrated saltation flux varies over three orders of magnitude among the sites, with the lowest mean flux recorded in the Taylor Valley (2.9 kg m-1 day-1) and the highest in the eastern Victoria Valley (2271 kg m-1 day -1) for 24 hours of continuous saltation. The percentage of time saltation active at these locations annually is ≈2%, ≈4%, and ≈13%, respectively, for the Victoria, Taylor, and Wright Valleys. Keypoints Characteristics of aeolian transport in Antarctica are described Frequency, magnitude, and seasonality of events presented Differences in saltation flux dynamics discussed ©2013. American Geophysical Union. All Rights Reserved.
Zimmerman P.,University of Guelph |
Vega I.,University of Guelph |
Poisson E.,University of Guelph |
Haas R.,California Institute of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013
We examine Hubeny's scenario according to which a near-extremal Reissner-Nordström black hole can absorb a charged particle and be driven toward an over-extremal state in which the charge exceeds the mass, signaling the destruction of the black hole. Our analysis incorporates the particle's electromagnetic self-force and the energy radiated to infinity in the form of electromagnetic waves. With these essential ingredients, our sampling of the parameter space reveals no instances of an overcharged final state, and we conjecture that the self-force acts as a cosmic censor, preventing the destruction of a near-extremal black hole by the absorption of a charged particle. We argue, on the basis of the third law of black hole mechanics, that this conclusion is robust and should apply to attempts to overspin a Kerr black hole. © 2013 American Physical Society.
Wirt H.K.,University of Helsinki |
Hebert P.D.N.,University of Guelph |
Kaartinen R.,University of Helsinki |
Prosser S.W.,University of Guelph |
And 2 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014
How networks of ecological interactions are structured has a major impact on their functioning. However, accurately resolving both the nodes of the webs and the links between them is fraught with difficulties. We ask whether the new resolution conferred by molecular information changes perceptions of network structure. To probe a network of antagonistic interactions in the High Arctic, we use two complementary sources of molecular data: parasitoid DNA sequenced from the tissues of their hosts and host DNA sequenced from the gut of adult parasitoids. The information added by molecular analysis radically changes the properties of interaction structure. Overall, three times as many interaction types were revealed by combining molecular information from parasitoids and hosts with rearing data, versus rearing data alone. At the species level, our results alter the perceived host specificity of parasitoids, the parasitoid load of host species, and the webwide role of predators with a cryptic lifestyle. As the northernmost network of host-parasitoid interactions quantified, our data point exerts high leverage on global comparisons of food web structure. However, how we view its structure will depend on what information we use: compared with variation among networks quantified at other sites, the properties of our web vary as much or much more depending on the techniques used to reconstruct it. We thus urge ecologists to combine multiple pieces of evidence in assessing the structure of interaction webs, and suggest that current perceptions of interaction structure may be strongly affected by the methods used to construct them.
Clare E.L.,University of Guelph |
Lim B.K.,Royal Ontario Museum |
Fenton M.B.,University of Western Ontario |
Hebert P.D.N.,University of Guelph
PLoS ONE | Year: 2011
DNA barcoding using the cytochrome c oxidase subunit 1 gene (COI) is frequently employed as an efficient method of species identification in animal life and may also be used to estimate species richness, particularly in understudied faunas. Despite numerous past demonstrations of the efficiency of this technique, few studies have attempted to employ DNA barcoding methodologies on a large geographic scale, particularly within tropical regions. In this study we survey current and potential species diversity using DNA barcodes with a collection of more than 9000 individuals from 163 species of Neotropical bats (order Chiroptera). This represents one of the largest surveys to employ this strategy on any animal group and is certainly the largest to date for land vertebrates. Our analysis documents the utility of this tool over great geographic distances and across extraordinarily diverse habitats. Among the 163 included species 98.8% possessed distinct sets of COI haplotypes making them easily recognizable at this locus. We detected only a single case of shared haplotypes. Intraspecific diversity in the region was high among currently recognized species (mean of 1.38%, range 0-11.79%) with respect to birds, though comparable to other bat assemblages. In 44 of 163 cases, well-supported, distinct intraspecific lineages were identified which may suggest the presence of cryptic species though mean and maximum intraspecific divergence were not good predictors of their presence. In all cases, intraspecific lineages require additional investigation using complementary molecular techniques and additional characters such as morphology and acoustic data. Our analysis provides strong support for the continued assembly of DNA barcoding libraries and ongoing taxonomic investigation of bats. © 2011 Clare et al.
Hajibabaei M.,University of Guelph |
Shokralla S.,University of Guelph |
Zhou X.,University of Guelph |
Singer G.A.C.,University of Guelph |
Baird D.J.,University of New Brunswick
PLoS ONE | Year: 2011
Timely and accurate biodiversity analysis poses an ongoing challenge for the success of biomonitoring programs. Morphology-based identification of bioindicator taxa is time consuming, and rarely supports species-level resolution especially for immature life stages. Much work has been done in the past decade to develop alternative approaches for biodiversity analysis using DNA sequence-based approaches such as molecular phylogenetics and DNA barcoding. On-going assembly of DNA barcode reference libraries will provide the basis for a DNA-based identification system. The use of recently introduced next-generation sequencing (NGS) approaches in biodiversity science has the potential to further extend the application of DNA information for routine biomonitoring applications to an unprecedented scale. Here we demonstrate the feasibility of using 454 massively parallel pyrosequencing for species-level analysis of freshwater benthic macroinvertebrate taxa commonly used for biomonitoring. We designed our experiments in order to directly compare morphology-based, Sanger sequencing DNA barcoding, and next-generation environmental barcoding approaches. Our results show the ability of 454 pyrosequencing of mini-barcodes to accurately identify all species with more than 1% abundance in the pooled mixture. Although the approach failed to identify 6 rare species in the mixture, the presence of sequences from 9 species that were not represented by individuals in the mixture provides evidence that DNA based analysis may yet provide a valuable approach in finding rare species in bulk environmental samples. We further demonstrate the application of the environmental barcoding approach by comparing benthic macroinvertebrates from an urban region to those obtained from a conservation area. Although considerable effort will be required to robustly optimize NGS tools to identify species from bulk environmental samples, our results indicate the potential of an environmental barcoding approach for biomonitoring programs. © 2011 Hajibabaei et al.
McNicholas P.D.,University of Guelph |
Murphy T.B.,University College Dublin
Bioinformatics | Year: 2010
Motivation: In recent years, work has been carried out on clustering gene expression microarray data. Some approaches are developed from an algorithmic viewpoint whereas others are developed via the application of mixture models. In this article, a family of eight mixture models which utilizes the factor analysis covariance structure is extended to 12 models and applied to gene expression microarray data. This modelling approach builds on previous work by introducing a modified factor analysis covariance structure, leading to a family of 12 mixture models, including parsimonious models. This family of models allows for the modelling of the correlation between gene expression levels even when the number of samples is small. Parameter estimation is carried out using a variant of the expectation-maximization algorithm and model selection is achieved using the Bayesian information criterion. This expanded family of Gaussian mixture models, known as the expanded parsimonious Gaussian mixture model (EPGMM) family, is then applied to two well-known gene expression data sets. Results: The performance of the EPGMM family of models is quantified using the adjusted Rand index. This family of models gives very good performance, relative to existing popular clustering techniques, when applied to real gene expression microarray data. © The Author 2010. Published by Oxford University Press. All rights reserved.
Curry R.A.,University of Guelph |
Curry R.A.,University of New Brunswick |
Neakes D.L.G.,University of Guelph
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2011
Spawning areas selected by brook trout (Salvelinus fontinalis) displayed variable relationships to discharging groundwater across geologic regions. In Canadian Shield waters, spawning was associated with areas of distinct, discharging groundwater. The specific mechanism of selection could not be determined. Groundwater did not appear to influence the selection of individual redd sites within these discharge areas. Competition among females for the opportunity to spawn in a limited area defined by the discharging groundwater appeared to control the selection of redd sites. In southwestern Ontario streams, discharging groundwater was prominent throughout areas of spawning both at redds and at adjacent, nonspawning substrates (≤7 m). Consequently, relationships between groundwater and spawning site selection were ambiguous. On the unglaciated plateau of central Pennsylvania, no groundwater was observed in redds or nonspawning substrates in streams. Brook trout management programmes must consider these groundwater relationships and therefore the impact of land use on groundwater quality and quantity. © 1995, (publisher). All rights reserved.
Acevedo N.C.,University of Guelph |
Block J.M.,Federal University of Santa Catarina |
Marangoni A.G.,University of Guelph
Faraday Discussions | Year: 2012
This article reports on the effect of laminar shear on structural and mechanical properties of physical mixtures of fully hydrogenated soybean oil (FHSO) in soybean oil (SO). Blends were crystallized statically and under laminar shear rates of 30 and 240 s-1 at different wall temperatures (-10, 0, 20 °C). The micro- and nanocrystalline structures were characterized using Polarized Light Microscopy (PLM), and Cryogenic Transmission Electron Microscopy (Cryo-TEM). Rheological analysis was used to determine changes in mechanical properties. Oil-binding capacity was analyzed through the measurement of the oil lost from the fat samples (OL). Shearing greatly affected the structure at the nano- and mesoscale. At low shear rates, blends displayed the largest increase in crystal size with an increase in wall temperature at both the nano- and mesoscale. On the other hand, at shear rates of 240 s -1, the effect of crystallization temperature was observed only at the nanoscale since no changes in meso-crystal sizes were observed at different temperatures. Crystallization under laminar shear promoted the growth of spherical crystalline particles at the mesoscale, called here "solid-lipid meso-particles". Crystallization under higher shear rates led to the formation of a weak network with low oil-binding capacity and promoted the asymmetric growth of nanoplatelets. In statically crystallized blends, nanoplatelets had an aspect ratio of ∼2, while in sheared blends this value increased significantly. These results revealed the existence of critical shear rate values above which strong alterations in the structure of the solid crystalline network took place. Shearing also affected the material's strength. Laminar shear induced a decrease in elastic modulus and yield stress values which was more pronounced at higher shear rate-temperature combinations. Shear-temperature combinations were successfully used to structure fats at the nano and mesoscale. © 2012 The Royal Society of Chemistry.
Bauch C.T.,University of Guelph |
Bauch C.T.,Princeton University |
Bhattacharyya S.,University of Guelph |
Bhattacharyya S.,University of Utah
PLoS Computational Biology | Year: 2012
Immunization programs have often been impeded by vaccine scares, as evidenced by the measles-mumps-rubella (MMR) autism vaccine scare in Britain. A "free rider" effect may be partly responsible: vaccine-generated herd immunity can reduce disease incidence to such low levels that real or imagined vaccine risks appear large in comparison, causing individuals to cease vaccinating. This implies a feedback loop between disease prevalence and strategic individual vaccinating behavior. Here, we analyze a model based on evolutionary game theory that captures this feedback in the context of vaccine scares, and that also includes social learning. Vaccine risk perception evolves over time according to an exogenously imposed curve. We test the model against vaccine coverage data and disease incidence data from two vaccine scares in England & Wales: the whole cell pertussis vaccine scare and the MMR vaccine scare. The model fits vaccine coverage data from both vaccine scares relatively well. Moreover, the model can explain the vaccine coverage data more parsimoniously than most competing models without social learning and/or feedback (hence, adding social learning and feedback to a vaccine scare model improves model fit with little or no parsimony penalty). Under some circumstances, the model can predict future vaccine coverage and disease incidence-up to 10 years in advance in the case of pertussis-including specific qualitative features of the dynamics, such as future incidence peaks and undulations in vaccine coverage due to the population's response to changing disease incidence. Vaccine scares could become more common as eradication goals are approached for more vaccine-preventable diseases. Such models could help us predict how vaccine scares might unfold and assist mitigation efforts. © 2012 Bauch, Bhattacharyya.
Wells C.R.,University of Guelph |
Klein E.Y.,Johns Hopkins University |
Bauch C.T.,University of Guelph
PLoS Computational Biology | Year: 2013
Theoretical models of infection spread on networks predict that targeting vaccination at individuals with a very large number of contacts (superspreaders) can reduce infection incidence by a significant margin. These models generally assume that superspreaders will always agree to be vaccinated. Hence, they cannot capture unintended consequences such as policy resistance, where the behavioral response induced by a new vaccine policy tends to reduce the expected benefits of the policy. Here, we couple a model of influenza transmission on an empirically-based contact network with a psychologically structured model of influenza vaccinating behavior, where individual vaccinating decisions depend on social learning and past experiences of perceived infections, vaccine complications and vaccine failures. We find that policy resistance almost completely undermines the effectiveness of superspreader strategies: the most commonly explored approaches that target a randomly chosen neighbor of an individual, or that preferentially choose neighbors with many contacts, provide at best a 2% relative improvement over their non-targeted counterpart as compared to 12% when behavioral feedbacks are ignored. Increased vaccine coverage in super spreaders is offset by decreased coverage in nonsuperspreaders, and superspreaders also have a higher rate of perceived vaccine failures on account of being infected more often. Including incentives for vaccination provides modest improvements in outcomes. We conclude that the design of influenza vaccine strategies involving widespread incentive use and/or targeting of superspreaders should account for policy resistance, and mitigate it whenever possible. © 2013 Wells et al.
Uchendu E.E.,University of Guelph |
Shukla M.R.,University of Guelph |
Reed B.M.,U.S. Department of Agriculture |
Saxena P.K.,University of Guelph
Journal of Pineal Research | Year: 2013
Climate change and global migrations of people and goods have exposed trees to new diseases and abiotic challenges that threaten the survival of species. In vitro germplasm storage via cryopreservation is an effective tool to ensure conservation of tree species, but plant cells and tissues are exposed to multiple stresses during the cryopreservation process. The current study was designed to evaluate the potential of melatonin to improve survival through the process of cryopreservation. Shoot tips of in vitro-grown plantlets and dormant winter buds of American elm were successfully cryopreserved in liquid nitrogen (LN) at -196°C under controlled environmental conditions following melatonin treatment and cold acclimation with either vitrification or encapsulation-vitrification protocols. Explants had optimal regrowth following cryopreservation when treated with the plant vitrification solution#2 (PVS2) for 10 min. Supplementation of both preculture and regrowth media with melatonin significantly enhanced regrowth of frozen shoots compared with the untreated control (P < 0.05). Approximately 80-100% of shoot explants grew under optimized conditions using melatonin-enriched media. Shoot tips of dormant winter buds consistently produced nearly 100% regrowth with both techniques. The main steps of the optimized protocol are 14-day cold-acclimated cultures exposed to preculture medium with 0.1-0.5 μm melatonin for 24 hr, application of PVS2 for 10 min, rapid cooling in LN, rapid rewarming, removal of cryoprotectants, and recovery on a medium supplemented with 0.1-0.5 μm melatonin. Our results demonstrate the usefulness of the antioxidant melatonin for long-term storage of naturally resistant elm germplasm. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Kekkonen M.,University of Helsinki |
Hebert P.D.N.,University of Guelph
Molecular Ecology Resources | Year: 2014
The analysis of DNA barcode sequences with varying techniques for cluster recognition provides an efficient approach for recognizing putative species (operational taxonomic units, OTUs). This approach accelerates and improves taxonomic workflows by exposing cryptic species and decreasing the risk of synonymy. This study tested the congruence of OTUs resulting from the application of three analytical methods (ABGD, BIN, GMYC) to sequence data for Australian hypertrophine moths. OTUs supported by all three approaches were viewed as robust, but 20% of the OTUs were only recognized by one or two of the methods. These OTUs were examined for three criteria to clarify their status. Monophyly and diagnostic nucleotides were both uninformative, but information on ranges was useful as sympatric sister OTUs were viewed as distinct, while allopatric OTUs were merged. This approach revealed 124 OTUs of Hypertrophinae, a more than twofold increase from the currently recognized 51 species. Because this analytical protocol is both fast and repeatable, it provides a valuable tool for establishing a basic understanding of species boundaries that can be validated with subsequent studies. © 2014 The Authors. Molecular Ecology Resources Published by John Wiley & Sons Ltd..
Baird D.J.,University of New Brunswick |
Hajibabaei M.,University of Guelph
Molecular Ecology | Year: 2012
Biological monitoring has failed to develop from simple binary assessment outcomes of the impacted/unimpacted type, towards more diagnostic frameworks, despite significant scientific effort over the past fifty years. It is our assertion that this is largely because of the limited information content of biological samples processed by traditional morphology-based taxonomy, which is a slow, imprecise process, focused on restricted groups of organisms. We envision a new paradigm in ecosystem assessment, which we refer to as 'Biomonitoring 2.0'. This new schema employs DNA-based identification of taxa, coupled with high-throughput DNA sequencing on next-generation sequencing platforms. We discuss the transformational nature of DNA-based approaches in biodiversity discovery and ecosystem assessment and outline a path forward for their future widespread application. © 2012 Crown in the right of Canada.
Mechoulam R.,Hebrew University of Jerusalem |
Parker L.,University of Guelph
British Journal of Pharmacology | Year: 2013
This commentary discusses the importance of a new study entitled 'Cannabidiol attenuates deficits of visuo-spatial associative memory induced by Δ9-tetrahydrocannabinol' by Wright et al. from the Scripps Institute in La Jolla, California. The results in this study show that the non-psychoactive cannabis constituent cannabidiol opposes some, but not all, forms of behavioural and memory disruption caused by Δ9- tetrahydrocannabinol in male rhesus monkeys. Linked Article This article is a commentary on the research paper by Wright et al., pp 1365-1373 of this issue. To view this paper visit http://dx.doi.org/10.1111/bph.12199 © 2013 The British Pharmacological Society.
News Article | March 14, 2016
The study, published today in Functional Ecology, is the first to explore how pesticides may impact the ability of bumblebees to forage from common wild flowers that have complex shapes such as white clover and bird's foot trefoil. Bees and other insects pollinate many of the world's important food crops and wild plants, and have been threatened in recent years. As such, there is an increasing need for field-realistic research into the impact of pesticides on bumblebees and other wild pollinators. In the study, bumblebees exposed to a realistic level of a neonicotinoid insecticide (thiamethoxam) collected more pollen but took longer to do so than control bees. Pesticide-exposed bees also chose to forage from a different flower in comparison to control bees. Professor Nigel Raine, University of Guelph (Canada), said: "Bees rely on learning to locate flowers, track their profitability and work-out how best to efficiently extract nectar and pollen. If exposure to low levels of pesticide affects their ability to learn, bees may struggle to collect food and impair the essential pollination services they provide to both crops and wild plants." Previous studies have found that exposure to neonicotinoid pesticides can cause changes in the brain, more specifically in the areas associated with learning and memory in honeybees. In this new study, the researchers found that, while bumblebees exposed to pesticides collected more pollen than control bees, control bees were able to learn how to manipulate these complex flowers after fewer visits. Dr Dara Stanley, Royal Holloway University of London, lead author of the study, said: "Bumblebees exposed to pesticide initially foraged faster and collected more pollen. However unexposed (control) bees may be investing more time and energy in learning. Our findings have important implications for society and the economy as pollinating insects are vital to support agriculture and wild plant biodiversity." "Our results suggest that current levels of pesticide-exposure could be significantly affecting how bees are interacting with wild-plants, and impairing the crucial pollination services they provide that support healthy ecosystem function," Raine added. Explore further: Exposure to pesticides results in smaller worker bees More information: Dara A. Stanley & Nigel E. Raine (2016) Chronic exposure to a neonicotinoid pesticide alters the interactions between bumblebees and wild plants. Functional Ecology DOI: 10.1111/1365-2435.12644
News Article | March 30, 2016
Bumblebees that have been exposed to neonicotinoid pesticides are slower to learn how best to collect pollen from wildflowers than are their unexposed counterparts. Neonicotinoids are widely used insecticides, and their application has been restricted in some countries because of their negative impact on bees. To study the effects of the chemicals on bee foraging, Dara Stanley at Royal Holloway University of London in Egham, UK, and Nigel Raine at the University of Guelph, Canada, observed individual bumblebees (Bombus terrestris) while the insects foraged on two species of wildflower. Bee colonies that had been dosed with the neonicotinoid thiamethoxam released more foragers, and these bees collected pollen more often than did controls. But unexposed bees required fewer visits to flowers to learn how to collect pollen efficiently. The results suggest that environmental exposure to this insecticide at sub-lethal levels probably changes how well bees forage and pollinate in the wild, say the authors.
Petrof E.O.,Queen's University |
Claud E.C.,University of Chicago |
Gloor G.B.,University of Western Ontario |
Allen-Vercoe E.,University of Guelph
Beneficial Microbes | Year: 2013
Increasing evidence indicates that the complex microbial ecosystem of the human intestine plays a critical role in protecting the host against disease. This review discusses gut dysbiosis (here defined as a state of imbalance in the gut microbial ecosystem, including overgrowth of some organisms and loss of others) as the foundation for several diseases, and the applicability of refined microbial ecosystem replacement therapies as a future treatment modality. Consistent with the concept of a 'core' microbiome encompassing key functions required for normal intestinal homeostasis, 'Microbial Ecosystem Therapeutics' (MET) would entail replacing a dysfunctional, damaged ecosystem with a fully developed and healthy ecosystem of 'native' intestinal bacteria. Its application in treating Clostridium difficile infection is discussed and possible applications to other diseases such as ulcerative colitis, obesity, necrotising enterocolitis, and regressive-type autism are reviewed. Unlike conventional probiotic therapies that are generally limited to a single strain or at most a few strains of bacteria 'Microbial Ecosystem Therapeutics' would utilise whole bacterial communities derived directly from the human gastrointestinal tract. By taking into account the intrinsic needs of the entire microbial ecosystem, MET would emphasise the rational design of healthy, resilient and robust microbial communities that could be used to maintain or restore human health. More than simply a new probiotic treatment, this emerging paradigm in medicine may lead to novel strategies in treating and managing a wide variety of human diseases. © 2013 Wageningen Academic Publishers.
Bell T.H.,University of Western Ontario |
Klironomos J.N.,University of Guelph |
Henry H.A.L.,University of Western Ontario
Soil Science Society of America Journal | Year: 2010
Soil microbial responses to climate warming in temperate regions may interact with the effects of increased atmospheric N deposition. In addition, the combined effects of these factors on microbial activity during the plant growing season may differ from the effects over winter, when reduced plant soil C inputs and soil freezing can alter microbial nutrient availability and demand. We examined seasonal changes in soil extracellular enzyme activity (EEA), microbial biomass C and N, and soil fungal and bacterial content in a warming and N addition experiment in a temperate old field. For EEA, we examined both hydrolases (organic C degrading enzymes, a chitinase and phosphatase) and ligninases (phenol oxidase and peroxidase). While both hydrolase and ligninase activities exhibited significant seasonal variation, EEA was unresponsive to the experimental treatments. Microbial biomass C increased with warming year round, however, and microbial biomass N increased with N addition but only over summer. Despite increased microbial biomass in response to warming, phosphatase was the only enzyme that exhibited a significant change in specific activity (enzyme activity per unit of microbial biomass) in response to warming. Likewise, soil fungal and bacterial biomass varied seasonally, but treatment effects on these variables were minimal. Overall, while the effects of N addition on microbial N varied seasonally, microbial responses were relatively insensitive to the warming and N addition treatments in our experiment. This insensitivity was unexpected given the large treatment effects on plant productivity and soil N dynamics documented during the same time frame in the field experiment. © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA All rights reserved.
Whitfield C.,University of Guelph |
Stephen Trent M.,University of Texas at Austin
Annual Review of Biochemistry | Year: 2014
Lipopolysaccharide molecules represent a unique family of glycolipids based on a highly conserved lipid moiety known as lipid A. These molecules are produced by most gram-negative bacteria, in which they play important roles in the integrity of the outer-membrane permeability barrier and participate extensively in host-pathogen interplay. Few bacteria contain lipopolysaccharide molecules composed only of lipid A. In most forms, lipid A is glycosylated by addition of the core oligosaccharide that, in some bacteria, provides an attachment site for a long-chain O-antigenic polysaccharide. The complexity of lipopolysaccharide structures is reflected in the processes used for their biosynthesis and export. Rapid growth and cell division depend on the bacterial cell's capacity to synthesize and export lipopolysaccharide efficiently and in large amounts. We review recent advances in those processes, emphasizing the reactions that are essential for viability. Copyright © 2014 by Annual Reviews.
Rahimi E.,Islamic Azad University |
Jalali M.,Isfahan University of Medical Sciences |
Weese J.S.,University of Guelph
BMC Public Health | Year: 2014
Background: Clostridium difficile has been shown to be a nosocomial pathogen associated with diarrhoea and pseudomembranous colitis in hospitalised patients and the infection is believed to be acquired nosocomially. Recent studies have shown the occurrence of C. difficile in food animals which may act as a source of infection to humans.The aim of this study was to determine the occurrence of C. difficile in retail raw beef, cow, sheep, goat, camel and buffalo meat in Iran. Method. From April to October 2012, a total of 660 raw meat samples from beef, cow, sheep, goat, camel and buffalo were purchased from 49 butcheries in Isfahan and Khuzestan provinces, Iran, and were evaluated for the presence of C. difficile using a method including selective enrichment in C. difficile broth, subsequent alcohol shock-treatment and plating onto C. difficile selective medium. C. difficile isolates were tested for the presence of toxin genes and were typed using PCR ribotyping. Results: In this study, 13 of 660 meat samples (2%) were contaminated with C. difficile. The highest prevalence of C. difficile was found in buffalo meat (9%), followed by goat meat (3.3%), beef meat (1.7%), cow (0.94%) and sheep meat (0.9%). Seven of the 13C. difficile strains (53.9%) were positive for tcdA, tcdB and cdtB toxin genes and were classified as ribotype 078. Four strains (30.8%) were positive tcdA, and tcdB, and one strain (7.7%) was possessed only tcdB. The remaining isolate was non-toxigenic. Susceptibilities of 13C. difficile isolates were determined for 11 antimicrobial drugs using the disk diffusion assay. Resistance to clindamycin, gentamycin, and nalidixic acid was the most common finding. Conclusions: To our knowledge, the present study is the first report of the isolation of C. difficile from raw buffalo meat. This study indicates the potential importance of food, including buffalo meat, as a source of transmission of C. difficile to humans. © 2014 Rahimi et al.; licensee BioMed Central Ltd.
Sikes B.A.,University of Texas at Austin |
Maherali H.,University of Guelph |
Klironomos J.N.,University of British Columbia
Oikos | Year: 2012
Plant interactions with soil biota could have a significant impact on plant successional trajectory by benefiting plants in a particular successional stage over others. The influence of soil mutualists such as mycorrhizal fungi is thought to be an important feedback component, yet they have shown benefits to both early and late successional plants that could either retard or accelerate succession. Here we first determine if arbuscular mycorrhizal (AM) fungi differ among three stages of primary sand dune succession and then if they alter growth of plants from particular successional stages. We isolated AM fungal inoculum from early, intermediate or late stages of a primary dune succession and compared them using cloning and sequencing. We then grew eight plant species that dominate within each of these successional stages with each AM fungal inoculum. We measured fungal growth to assess potential AM functional differences and plant growth to determine if AM fungi positively or negatively affect plants. AM fungi isolated from early succession were more phylogenetically diverse relative to intermediate and late succession while late successional fungi consistently produced more soil hyphae and arbuscules. Despite these differences, inocula from different successional stages had similar effects on the growth of all plant species. Host plant biomass was not affected by mycorrhizal inoculation relative to un-inoculated controls. Although mycorrhizal communities differ among primary dune successional stages and formed different fungal structures, these differences did not directly affect the growth of plants from different dune successional stages in our experiment and therefore may be less likely to directly contribute to plant succession in sand dunes. © 2012 The Authors. Oikos © 2012 Nordic Society Oikos.
Clare E.L.,University of Guelph |
Barber B.R.,University of Western Ontario |
Sweeney B.W.,Stroud Water Research Center |
Hebert P.D.N.,University of Guelph |
Fenton M.B.,University of Western Ontario
Molecular Ecology | Year: 2011
We employ molecular methods to profile the diet of the little brown bat, Myotis lucifugus, and describe spatial and temporal changes in diet over their maternity season. We identified 61 prey species of insects and 5 species of arachnid. The largest proportion of prey (∼32%) were identified as species of the mass-emerging Ephemeroptera (mayfly) genus Caenis. Bats roosting in agricultural settings had lower dietary richness than those occupying a roost located on a forest fragment in a conservation area. We detected temporal fluctuations in diet over the maternity season. Dipteran (fly) species dominated the diet early in the season, replaced later by species of mayfly. Because our methodology provides species-level identification of prey, we were able to isolate environmental indicator species in the diet and draw conclusions about the location and type of their foraging habitat and the health of these aquatic systems. The species detected suggested that the bats use variable habitats; members of one agricultural roost foraged on insects originating in rivers or streams while those in another agricultural roost and the forest roost fed on insects from pond or lake environments. All source water for prey was of fair to good quality, though no species detected are intolerant of pollution thus the habitat cannot be classified as pristine. Our study outlines a model system to investigate the abiotic and biotic interactions between habitat factors through this simple food chain to the top predator. © 2011 Blackwell Publishing Ltd.
Sargolzaei M.,University of Guelph |
Chesnais J.P.,Semex Alliance |
Schenkel F.S.,University of Guelph
BMC Genomics | Year: 2014
Background: Genotype imputation can help reduce genotyping costs particularly for implementation of genomic selection. In applications entailing large populations, recovering the genotypes of untyped loci using information from reference individuals that were genotyped with a higher density panel is computationally challenging. Popular imputation methods are based upon the Hidden Markov model and have computational constraints due to an intensive sampling process. A fast, deterministic approach, which makes use of both family and population information, is presented here. All individuals are related and, therefore, share haplotypes which may differ in length and frequency based on their relationships. The method starts with family imputation if pedigree information is available, and then exploits close relationships by searching for long haplotype matches in the reference group using overlapping sliding windows. The search continues as the window size is shrunk in each chromosome sweep in order to capture more distant relationships.Results: The proposed method gave higher or similar imputation accuracy than Beagle and Impute2 in cattle data sets when all available information was used. When close relatives of target individuals were present in the reference group, the method resulted in higher accuracy compared to the other two methods even when the pedigree was not used. Rare variants were also imputed with higher accuracy. Finally, computing requirements were considerably lower than those of Beagle and Impute2. The presented method took 28 minutes to impute from 6 k to 50 k genotypes for 2,000 individuals with a reference size of 64,429 individuals.Conclusions: The proposed method efficiently makes use of information from close and distant relatives for accurate genotype imputation. In addition to its high imputation accuracy, the method is fast, owing to its deterministic nature and, therefore, it can easily be used in large data sets where the use of other methods is impractical. © 2014 Sargolzaei et al.; licensee BioMed Central Ltd.
Juhasz J.,Hamilton Health Sciences |
Davis J.H.,University of Guelph |
Sharom F.J.,University of Guelph
Biochemical Journal | Year: 2010
Direct visualization of raft-like lo (liquid-ordered) domains in model systems and cells using microscopic techniques requires fluorescence probes with known partitioning preference for one of the phases present. However, fluorescent probes may display dissimilar partitioning preferences in different lipid systems and can also affect the phase behaviour of the host lipid bilayer. Therefore a detailed understanding of the behaviour of fluorescent probes in defined lipid bilayer systems with known phase behaviour is essential before they can be used for identifying domain phase states. Using giant unilamellar vesicles composed of the ternary lipid mixture DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine)/DPPC (1,2-dipalmitoyl-sn-glycero-3- phosphocholine)/cholesterol, for which the phase behaviour is known, we examined nine commonly used fluorescent probes using confocal fluorescence microscopy. The partitioning preference of each probe was assigned either on the basis of quantification of the domain area fractions or by using a well-characterized ld (liquid-disordered)-phase marker. Fluorescent probes were examined both individually and using dual or triple labelling approaches. Most of the probes partitioned individually into the ld phase, whereas only NAP (naphtho[2,3-a]pyrene) and NBD-DPPE [1,2-dipalmitoyl-sn-glycero-3- phosphoethanolamine-N-(7-nitro-2-1, 3-benzoxadiazol-4-yl] preferred the l o phase. We found that Rh-DPPE (Lissamine™ rhodamine B-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine) increased the miscibility transition temperature, Tmix. Interestingly, the partitioning of DiIC18 (1,1′-dioctadecyl-3,3,3′,3′- tetramethylindocarbocyanine perchlorate) was influenced by Bodipy®-PC [2-(4,4-difluoro-5, 7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-1- hexadecanoyl-sn-glycero-3-phosphocholine]. The specific use of each of the fluorescent probes is determined by its photostability, partitioning preference, ability to detect lipid phase separations and induced change in T mix. We demonstrate the importance of testing a specific fluorescent probe in a given model membrane system, rather than assuming that it labels a particular lipid phase. © The Authors.
Balasubramanian V.,University of Western Ontario |
Buchel A.,University of Western Ontario |
Buchel A.,Perimeter Institute for Theoretical Physics |
Green S.R.,University of Guelph |
And 2 more authors.
Physical Review Letters | Year: 2014
For a real massless scalar field in general relativity with a negative cosmological constant, we uncover a large class of spherically symmetric initial conditions that are close to anti-de Sitter space (AdS) but whose numerical evolution does not result in black hole formation. According to the AdS/conformal field theory (CFT) dictionary, these bulk solutions are dual to states of a strongly interacting boundary CFT that fail to thermalize at late times. Furthermore, as these states are not stationary, they define dynamical CFT configurations that do not equilibrate. We develop a two-time-scale perturbative formalism that captures both direct and inverse cascades of energy and agrees with our fully nonlinear evolutions in the appropriate regime. We also show that this formalism admits a large class of quasiperiodic solutions. Finally, we demonstrate a striking parallel between the dynamics of AdS and the classic Fermi-Pasta-Ulam-Tsingou problem. © 2014 American Physical Society.
Roy M.M.,Lakehead University |
Dutta A.,University of Guelph |
Corscadden K.,Dalhousie University
Applied Energy | Year: 2013
This study presents combustion and emission results obtained using a prototype pellet furnace with 7-32kW capacity (designed for burning high ash content pellet fuels) for four biomass pellets: one grass pellet and three wood pellets. Fuel property, gas emissions and furnace efficiency are compared. In regard to fuel properties, proximate analysis, ultimate analysis and heating values are determined and emissions of carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO2), nitrogen oxides (NOx) and sulfur dioxide (SO2) are measured and compared. Scanning electron microscopy (SEM) was used for ash analysis. No ash agglomeration was observed and ash discharge was in the form of powder instead of lumped particles, which are usually observed for high ash biomass fuel. The results suggest that grass pellets can successfully be combusted with similar performance and emissions to that of other wood pellets if burned in appropriate combustion installations. © 2013 Elsevier Ltd.
Fatila E.M.,University of Guelph |
Rouzieires M.,CNRS Paul Pascal Research Center |
Jennings M.C.,FreeLance Crystallography |
Lough A.J.,University of Toronto |
And 2 more authors.
Journal of the American Chemical Society | Year: 2013
A supramolecular species composed of a pair of nonequivalent Dy(III)-radical complexes exhibits single-molecule magnet (SMM) properties. The weak effective antiferromagnetic coupling between the Dy(III) ions can be compensated by application of a small (700 Oe) dc field, revealing the relaxation mode of the two distinct SMMs. These unique results illustrate how the dynamics of a supramolecular [Dy-Radical]2 SMM can be fine-tuned by the exchange-bias and an applied magnetic field. © 2013 American Chemical Society.
Wang Y.,University of Hong Kong |
Jiao J.J.,University of Hong Kong |
Cherry J.A.,University of Guelph
Science of the Total Environment | Year: 2012
Elevated concentrations of arsenic, up to 161 μg/L, have been identified in groundwater samples from the confined basal aquifer underlying the aquitard of the Pearl River Delta (PRD). Both aquatic arsenic in pore water and solid arsenic in the sediments in the basal aquifer and aquitard were identified. Arsenic speciation of groundwater in the basal aquifer was elucidated on a pH-Eh diagram. In the PRD, arsenic is enriched in groundwater having both low and high salinity, and arsenic enriched groundwater is devoid of dissolved oxygen, has negative Eh values, is slightly alkaline, and has abnormally high concentrations of ammonium and dissolved organic carbon, but low concentrations of nitrate and nitrite. Results of geochemical and hydrochemical analyses and sequential extraction analysis suggest that reductive dissolution of iron oxyhydroxide could be one of the important processes that mobilized solid arsenic. We speculate that mineralization of sedimentary organic matter could also contribute to aquatic arsenic. Scanning electron microscope analysis confirms that abundant authigenic pyrite is present in the sediments. Sulphate derived from paleo-seawater served as the important sulfur source for authigenic pyrite formation. Co-precipitation of arsenic with authigenic pyrite significantly controlled concentrations of aquatic arsenic in the coastal aquifer-aquitard system. © 2012 Elsevier B.V.
Mueller A.S.,University of Western Ontario |
Trick L.M.,University of Guelph
Accident Analysis and Prevention | Year: 2012
Inexperience is one of the strongest predictors for collisions, but it remains unclear how novice drivers differ from experienced drivers in terms of safety-related behavioural adaptations such as speed reduction in the presence of reduced visibility. To investigate the influence of driving experience on behavioural compensations to fog, average speed, speed variability, steering variability, collision rate, and hazard response time were measured in a driving simulator. Experienced drivers drove faster in clear visibility than novice drivers, yet they reduced their speed more in reduced visibility so that both groups drove at the same speed in simulated fog. Compared to experienced drivers, novice drivers had higher hazard response times, greater speed and steering variability, and were the only drivers to have collisions. © 2012 Elsevier Ltd. All rights reserved.
Pan Y.,University of Western Ontario |
Brown L.,University of Guelph |
Konermann L.,University of Western Ontario
Journal of the American Chemical Society | Year: 2011
Many proteins act as molecular machines that are fuelled by a nonthermal energy source. Examples include transmembrane pumps and stator-rotor complexes. These systems undergo cyclic motions (CMs) that are being driven along a well-defined conformational trajectory. Superimposed on these CMs are thermal fluctuations (TFs) that are coupled to stochastic motions of the solvent. Here we explore whether the TFs of a molecular machine are affected by the occurrence of CMs. Bacteriorhodopsin (BR) is a light-driven proton pump that serves as a model system in this study. The function of BR is based on a photocycle that involves trans/cis isomerization of a retinal chromophore, as well as motions of transmembrane helices. Hydrogen/deuterium exchange (HDX) mass spectrometry was used to monitor the TFs of BR, focusing on the monomeric form of the protein. Comparative HDX studies were conducted under illumination and in the dark. The HDX kinetics of BR are dramatically accelerated in the presence of light. The isotope exchange rates and the number of backbone amides involved in EX2 opening transitions increase roughly 2-fold upon illumination. In contrast, light/dark control experiments on retinal-free protein produced no discernible differences. It can be concluded that the extent of TFs in BR strongly depends on photon-driven CMs. The light-induced differences in HDX behavior are ascribed to protein destabilization. Specifically, the thermodynamic stability of the dark-adapted protein is estimated to be 5.5 kJ mol -1 under the conditions of our work. This value represents the free energy difference between the folded state F and a significantly unfolded conformer U. Illumination reduces the stability of F by 2.2 kJ mol -1. Mechanical agitation caused by isomerization of the chromophore is transferred to the surrounding protein scaffold, and subsequently, the energy dissipates into the solvent. Light-induced retinal motions therefore act analogously to an internal heat source that promotes the occurrence of TFs. Overall, our data highlight the potential of HDX methods for probing the structural dynamics of molecular machines under "engine on" and "engine off" conditions. © 2011 American Chemical Society.
Goss M.J.,University of Guelph |
Tubeileh A.,University of Guelph |
Goorahoo D.,California State University, Fresno
Advances in Agronomy | Year: 2013
Historically, organic amendments-organic wastes-have been the main source of plant nutrients, especially N. Their use allows better management of often-finite resources to counter changes in soils that result from essential practices for crop production. Organic amendments provide macro- and micronutrients, including carbon for the restoration of soil physical and chemical properties. Challenges from the use of organic amendments arise from the presence of heavy metals and the inability to control the transformations required to convert the organic forms of N and P into the minerals available to crops, and particularly to minimize the losses of these nutrients in forms that may present a threat to human health. Animal manure and sewage biosolids, the organic amendments in greatest abundance, contain components that can be hazardous to human health, other animals and plants. Pathogens pose an immediate threat. Antibiotics, other pharmaceuticals and naturally produced hormones may pose a threat if they increase the number of zoonotic disease organisms that are resistant to multiple antimicrobial drugs or interfere with reproductive processes. Some approaches aimed at limiting N losses (e.g. covered liquid or slurry storage, rapid incorporation into the soil, timing applications to minimize delay before plant uptake) also tend to favor survival of pathogens. Risks to human health, through the food chain and drinking water, from the pathogens, antibiotics and hormonal substances that may be present in organic amendments can be reduced by treatment before land application, such as in the case of sewage biosolids. Other sources, such as livestock and poultry manures, are largely managed by ensuring that they are applied at the rate, time and. place most appropriate to the crops and soils. A more holistic approach to management is required as intensification of agriculture increases. © 2013 Elsevier Inc.
News Article | February 24, 2017
An international team of researchers, funded by Morris Animal Foundation, has shown that adipose (fat) stem cells might be the preferred stem cell type for use in canine therapeutic applications, including orthopedic diseases and injury. Researchers at the University of Guelph, University of Western Ontario and Aarhus University, Denmark, ran a battery of tests comparing the physiology characteristics of stem cells derived from adipose tissue versus bone marrow. They found that stem cells from both sources had similar functional properties, including tissue generation and immunomodulating capabilities (ability to adjust immune response), but adipose stem cells grow at a faster rate than bone marrow stem cells. Harvesting adipose stem cells also is less invasive than harvesting bone marrow. The study recently was published in PLoS ONE, an online scientific journal. In the last decade, the use of stem cell therapy in animals and humans has dramatically increased. In dogs, stem cell therapy is used in the treatment of a variety of orthopedic diseases and injuries. Stem cells are harvested from either fat tissue or bone marrow, purified and grown in culture, then placed back in the patient. Given the ease of harvesting, adipose tissue has become the site of most stem cell collections in canine patients. But questions persisted regarding the differences between these two sources of stem cells, and which is better suited to therapeutic applications. "Faster proliferation along with the potential for a less invasive method of their procurement makes them (adipose stem cells) the preferred source for canine mesenchymal stem cells," concluded the research team. Morris Animal Foundation is a global leader in funding scientific studies that advance the health of companion animals, horses and wildlife. Since its founding in 1948, the Foundation has invested over $113 million in more than 2,500 studies that have led to significant breakthroughs in the diagnosis, treatment and prevention of disease to benefit animals worldwide. Publication reference: Russell KA, Chow NHC, Dukoff D, Gibson TWG, LaMarre J, Betts DH, et al. (2016) Characterization and Immunomodulatory Effects of Canine Adipose Tissue- and Bone Marrow-Derived Mesenchymal Stromal Cells. PLoS ONE 11(12):e0167442. doi:10.1371/journal.pone.0167442
News Article | February 27, 2017
Vegesentials, the multiple international award-winning high-pressure pasteurized cold-pressed fruit and vegetable drink brand is now available on Amazon.com. In 2016, the London-based Vegesentials Ltd. partnered with Michigan-based Vegesentials USA, LLC to manufacture and distribute the Vegesentials line of juices throughout North America. Registered Dietitian Nutritionist (“RDN”) Nanette Cameron has been working with Vegesentials to improve their cold-pressed juices for children and young adults. Commenting on the ingredients of Vegesentials offerings, Cameron notes the added fiber “promotes blood sugar stabilization, but what it means is energy balance to improve a child’s focus and mood; something that is so important for learning and academics.” She continues that “digestive health refers to keeping healthy floral in the stomach, this decreases stomach pain, constipation, diarrhea, another common issue among children and many young adults.” Studying the various Vegesentials recipes and contents, Cameron commented, “What I like about these juices is the cold pressurized process. The nutrients from the fruit and vegetables are maintained; this is something that is not listed on a nutritional label. Consuming anti-oxidants and phyto-chemicals have been linked to a healthy immune system and prevention of disease.” The Vegesentials labels are “clean, and that’s what we advise our constituents to be on the look-out for: ‘clean labeling.’” As part of the required North American validation of the juice contents, Vegesentials retained the Department of Food Science at the University of Guelph (Ontario, CA) to certify its HPP process and juice ingredients. According to Dr. Keith Warriner, the aim of the validations is “to determine the efficacy of different HHP treatments to reduce model pathogens introduced into high acid juices.” Because HPP technology is relatively new and fresh juice has become so popular, Dr. Warriner will continue his academic research with Vegesentials to improve food safety for consumers. “The results [of our testing] indicate that juice formulation has a role in defining the pressure resistance of pathogens although which constituents provide protection to HHP remain unclear.” "Our biggest concern as a company is customer health," said Daniel Hoops, Vegesentials USA co-founder. "When you look at the vast array of cold-pressed juices sold on the Internet, few use the HPP technology. In addition to our juices having longer shelf life, we know that there is little to no risk of salmonella, ecoli, and other food-borne bacteria because we use HPP." Vegesentials is the United Kingdom’s first cold pressed vegetable and fruit drink brand. Following its launch in June 2012, Vegesentials can now be found in all but one WholeFoods in the U.K., 60% of the Waitrose supermarkets, and 50% of the Holland and Barrett outlets. Vegesentials has received numerous awards and recognition since its initial launch, including 2 Gold Stars awards for Superior Taste from the International Taste & Quality Institute, Winner of ‘the Health & Fitness Food and Drink ‘Smoothie Category 2014 Award’ by Women’s Fitness and Health & Fitness Magazines, Gold in the low calorie food and drink category by Women’s Fitness and Health & Fitness 2016, Voted as No.1 ‘Highly Recommended’ Drink at Be:Fit London Show 2014 by ‘Science of Fit’, Winner of 'Best Exhibitor Award 2014’ at The Food & Drink Expo Trade Show NEC Birmingham, UK’s largest ‘Food & Drink’ trade show in 2014, and Finalist for Grocer Gold Award for “Entrepreneur of 2014.” “We thought the American consumer might be a little hesitant to try a ‘foreign’ fruit and vegetable juice, but all of the feedback from our testing groups have come back with high marks. It’s been incredible and we’re honored to be the exclusive distributor here in North America.” Cameron said “I was genuinely shocked to hear my 16-year old nephew (who despises carrots) tell me that the Cheeky Carrot juice was ‘the best juice I have ever tasted!’ That was all the validation I needed.” Vegesentials USA will offer Amazon.com customers the Vegesentials 8.8oz Cheeky Carrot (carrot, apple, orange, lime, and chicory root), Cool Cucumber (cucumber, apple, spinach and chicory root), and Groovy Beet (beetroot, apple, cucumber, strawberry and chicory root). The child and senior version of these juices, sold in a 4.4oz bottle, will be available on Amazon.com at a later date. For more information about Vegesentials, visit http://www.vegesentials.co.uk or http://www.vegesentialsusa.com.
Michel V.,University of New Mexico |
Bakovic M.,University of Guelph
Central Nervous System Agents in Medicinal Chemistry | Year: 2012
Choline is a zwitter ion that is positively charged at certain pH, which necessitates transport systems to allow this amine to cross the phospholipid bilayer of cellular membranes. The solute carrier 44A1 (SLC44A1), also referred to as choline transporter-like protein 1 (CTL1), is a recently discovered choline transporter with an intermediate affinity for choline; this transport is Na+-independent and sensitive to inhibition by the drug hemicholinium-3. We highlight in this review the discovery and characterization of SLC44A1, describe its expression patterns and subcellular localization, and summarize evidence for the role of this choline transporter in the central nervous system. © 2012 Bentham Science Publishers.
Palenzuela C.,Canadian Institute for Theoretical Astrophysics |
Barausse E.,CNRS Paris Institute of Astrophysics |
Ponce M.,University of Guelph |
Lehner L.,Perimeter Institute for Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014
We present a framework to study generic neutron-star binaries in scalar-tensor theories of gravity. Our formalism achieves this goal by suitably interfacing a post-Newtonian orbital evolution (described by a set of ordinary differential equations) with a set of nonlinear algebraic equations, which provide a description of the scalar charge of each binary's component along the evolution in terms of isolated-star data. We validate this semianalytical procedure by comparing its results to those of fully general-relativistic simulations, and use it to investigate the behavior of binary systems in large portions of the parameter space of scalar-tensor theories. This allows us to shed further light on the phenomena of "dynamical scalarization," which we uncovered in [E. Barausse et al., Phys. Rev. D 87, 081506(R) (2013)] and which takes place in tight binaries, even for stars that have exactly zero scalar charge in isolation. We also employ our formalism to study representative binary systems, obtain their gravitational-wave signals and discuss the extent to which deviations from general relativity can be detected. The insights gained by this framework allow us to additionally show that eccentric binaries can undergo scalarization/descalarization phenomena. © 2014 American Physical Society.
Ernst J.B.,University of Guelph |
Kremer S.C.,University of Guelph |
Rodrigues J.J.P.C.,University of Beira Interior
Physical Communication | Year: 2014
Heterogeneous Wireless Networks (HWNs) are an important step in making connectivity ubiquitous and pervasive. Leveraging the increasing variety of connectivity options available to devices solves many problems such as capacity, spectrum efficiency, coverage and reliability. Anytime decisions are made for selection, handover, scheduling or routing many performance metrics along with energy efficiency and cost for access must be considered. The increased number of choices in an HWN makes the problem more difficult than traditional homogeneous networks since each Radio Access Technology (RAT) has unique characteristics. For instance, Bluetooth networks have low range and speed but are cheap compared to 4G networks. These types of observations can be factored into decision making in HWNs. Quality of Service and Experience should be considered so that the best possible configuration of connectivity, price and user application is made. All of this should occur autonomously. This paper provides a survey of recent works in HWNs with these ideas in mind. Existing approaches are categorized by function. Limitations and strengths of solutions are highlighted and comparisons between approaches are made to provide a starting point for further research in the area. © 2014 Published by Elsevier B.V.
Poisson E.,University of Guelph |
Poisson E.,CNRS Paris Institute of Astrophysics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015
In the first part of this article I determine the geometry of a slowly rotating black hole deformed by generic tidal forces created by a remote distribution of matter. The metric of the deformed black hole is obtained by integrating the Einstein field equations in a vacuum region of spacetime bounded by r
Moayyedi P.,McMaster University |
Surette M.G.,McMaster University |
Kim P.T.,University of Guelph |
Kim P.T.,McMaster University |
And 8 more authors.
Gastroenterology | Year: 2015
Background & Aims Ulcerative colitis (UC) is difficult to treat, and standard therapy does not always induce remission. Fecal microbiota transplantation (FMT) is an alternative approach that induced remission in small series of patients with active UC. We investigated its safety and efficacy in a placebo-controlled randomized trial. Methods We performed a parallel study of patients with active UC without infectious diarrhea. Participants were examined by flexible sigmoidoscopy when the study began and then were randomly assigned to groups that received FMT (50 mL, via enema, from healthy anonymous donors; n = 38) or placebo (50 mL water enema; n = 37) once weekly for 6 weeks. Patients, clinicians, and investigators were blinded to the groups. The primary outcome was remission of UC, defined as a Mayo score ≤2 with an endoscopic Mayo score of 0, at week 7. Patients provided stool samples when the study began and during each week of FMT for microbiome analysis. The trial was stopped early for futility by the Data Monitoring and Safety Committee, but all patients already enrolled in the trial were allowed to complete the study. Results Seventy patients completed the trial (3 dropped out from the placebo group and 2 from the FMT group). Nine patients who received FMT (24%) and 2 who received placebo (5%) were in remission at 7 weeks (a statistically significant difference in risk of 17%; 95% confidence interval, 2%-33%). There was no significant difference in adverse events between groups. Seven of the 9 patients in remission after FMT received fecal material from a single donor. Three of the 4 patients with UC ≤1 year entered remission, compared with 6 of 34 of those with UC >1 year (P =.04, Fisher's exact test). Stool from patients receiving FMT had greater microbial diversity, compared with baseline, than that of patients given the placebo (P =.02, Mann-Whitney U test). Conclusions FMT induces remission in a significantly greater percentage of patients with active UC than placebo, with no difference in adverse events. Fecal donor and time of UC appear to affect outcomes. ClinicalTrials.gov Number: NCT01545908. © 2015 AGA Institute.
Nasser N.,Alfaisal University |
Karim L.,University of Guelph |
Taleb T.,NEC Europe
IEEE Transactions on Wireless Communications | Year: 2013
Scheduling different types of packets, such as real-time and non-real-time data packets, at sensor nodes with resource constraints in Wireless Sensor Networks (WSN) is of vital importance to reduce sensors' energy consumptions and end-to-end data transmission delays. Most of the existing packet-scheduling mechanisms of WSN use First Come First Served (FCFS), non-preemptive priority and preemptive priority scheduling algorithms. These algorithms incur a high processing overhead and long end-to-end data transmission delay due to the FCFS concept, starvation of high priority real-time data packets due to the transmission of a large data packet in non-preemptive priority scheduling, starvation of non-real-time data packets due to the probable continuous arrival of real-time data in preemptive priority scheduling, and improper allocation of data packets to queues in multilevel queue scheduling algorithms. Moreover, these algorithms are not dynamic to the changing requirements of WSN applications since their scheduling policies are predetermined. In this paper, we propose a Dynamic Multilevel Priority (DMP) packet scheduling scheme. In the proposed scheme, each node, except those at the last level of the virtual hierarchy in the zone-based topology of WSN, has three levels of priority queues. Real-time packets are placed into the highest-priority queue and can preempt data packets in other queues. Non-real-time packets are placed into two other queues based on a certain threshold of their estimated processing time. Leaf nodes have two queues for real-time and non-real-time data packets since they do not receive data from other nodes and thus, reduce end-to-end delay. We evaluate the performance of the proposed DMP packet scheduling scheme through simulations for real-time and non-real-time data. Simulation results illustrate that the DMP packet scheduling scheme outperforms conventional schemes in terms of average data waiting time and end-to-end delay. © 2002-2012 IEEE.
Josephy P.D.,University of Guelph |
Novak M.,Miami University Ohio
Frontiers in Bioscience - Scholar | Year: 2013
Aromatic and heterocyclic amines are a major class of chemical mutagens and carcinogens. The toxicity of these compounds is a consequence of their metabolic activation. The best-characterized enzymatic pathways for aromatic amine activation lead to the formation of reactive esters such as N-acetoxyarylamines, which are believed to be precursors of short-lived nitrenium ions. In the 1960s, nitrenium ions were invoked as likely intermediates in the formation of arylamine-derived DNA adducts. More recently, nitrenium ion chemistry has been studied by methods such as trapping with azide ion, laser flash photolysis, and the preparation of highly stabilized of examples (e.g., dianisylnitrenium ion). In this review, we discuss the development of our understanding of nitrenium ion chemistry, with emphasis on their generation in biological systems and their reactions with critical targets such as DNA.
Zeng B.,University of Guelph |
Cross A.,SAIC |
Chuang I.L.,Massachusetts Institute of Technology
IEEE Transactions on Information Theory | Year: 2011
Logic gates can be performed on data encoded in quantum code blocks such that errors introduced by faulty gates can be corrected. The important class of transversal gates acts bitwise between corresponding qubits of code blocks and thus limits error propagation. If any quantum gate could be implemented using transversal gates, the set would be universal. We study the structure of GF(4)-additive quantum codes and prove that no universal set of transversal logic gates exists for these codes. This result is in stark contrast with the classical case, where universal transversal gate sets exist, and strongly supports the idea that additional quantum techniques, based, for example, on quantum teleportation or magic state distillation, are necessary to achieve universal fault-tolerant quantum computation on additive codes. © 2011 IEEE.
Queen's University, University of Guelph and Kingston General Hospital | Date: 2012-09-14
There are provided novel synthetic stool preparations comprising bacteria isolated from a fecal sample from a healthy donor. The synthetic stool preparations are used for treating disorders of the gastrointestinal tract, including dysbiosis, Clostridium difficile infection and recurrent Clostridium difficile infection, prevention of recurrence of Clostridium difficile infection, treatment of Crohns disease, ulcerative colitis, irritable bowel syndrome, inflammatory bowel disease, and diverticular disease, and treatment of food poisoning such as salmonella. Methods of preparation and methods of use of the synthetic stool preparations are also provided.
News Article | April 26, 2016
Soy isoflavones and peptides may inhibit the growth of microbial pathogens that cause food-borne illnesses, according to a new study from University of Guelph researchers. Soybean derivatives are already a mainstay in food products, such as cooking oils, cheeses, ice cream, margarine, food spreads, canned foods and baked goods. The use of soy isoflavones and peptides to reduce microbial contamination could benefit the food industry, which currently uses synthetic additives to protect foods, says engineering professor Suresh Neethirajan, director of the BioNano Laboratory. U of G researchers used microfluidics and high-throughput screening to run millions of tests in a short period. They found that soy can be a more effective antimicrobial agent than the current roster of synthetic chemicals. The study is set to be published in the journal Biochemistry and Biophysics Reports this summer and is available online now. "Heavy use of chemical antimicrobial agents has caused some strains of bacteria to become very resistant to them, rendering them ineffective for the most part," said Neethirajan. "Soy peptides and isoflavones are biodegradable, environmentally friendly and non-toxic. The demand for new ways to combat microbes is huge, and our study suggests soy-based isoflavones and peptides could be part of the solution." Neethirajan and his team found soy peptides and isoflavones limited growth of some bacteria, including Listeria and Pseudomonas pathogens. "The really exciting thing about this study is that it shows promise in overcoming the issue of current antibiotics killing bacteria indiscriminately, whether they are pathogenic or beneficial. You need beneficial bacteria in your intestines to be able to properly process food," he said. Peptides are part of proteins, and can act as hormones, hormone producers or neurotransmitters. Isoflavones act as hormones and control much of the biological activity on the cellular level. North America has one of the safest food sources in the world, said Neethirajan, but the United States Centers for Disease Control and Prevention estimates that about 48 million people in the U.S. suffer from some sort of food-borne illness every year. "In addition, some people are worried about the potential for long-term illnesses resulting from the use of synthetic chemicals," Neethirajan said. "The use of soy peptides and isoflavones could combat bacteria and reduce these concerns." The next step is for researchers to conduct large-scale tests, Neethirajan said. "We've created a recipe for this to go ahead. This could be very beneficial to food processors, as well as the farmers who grow soy beans."
News Article | February 28, 2017
The chicken meat that Subway restaurants serve to their customers may only have about 50 percent chicken DNA. In a Canadian Broadcasting Corporation Marketplace investigation, researchers at Trent University Wildlife Forensic DNA Laboratory tested chicken meat from fast food chains which included Wendy's, McDonald's, Tim Horton's, A&W, and Subway. Chickens sold in supermarkets need to test at 100 percent chicken DNA. The standard, however, is lowered when it comes to meat that has been marinated, seasoned or prepared such as those sold in food chains so they may have lower chicken DNA percentage. Chicken meat from most of the fast food chains had scores from 85 to 90 percent chicken DNA except Subway, which showed far lower percentage for chicken DNA. The score of Subway's oven roasted chicken was 53.6 percent chicken DNA while the Sweet Onion Chicken Teriyaki scored a mere 42.8 percent. What's in Subway's chicken meat? DNA tests revealed it is soy but Subway Canada said in a statement that they cannot confirm the veracity of the lab tests' results. The company said that its oven roasted chicken and chicken strips contain only 1 percent or less of soy protein, which it uses to stabilize mixture and texture. The company added that all of the chicken items it offers are 100 percent white meat chicken that has been marinated, oven-roasted and grilled. "We tested our chicken products recently for nutritional and quality attributes and found it met our food quality standards," Subway said adding that it will look into the matter with its supplier to ascertain that the chicken it offers to customers meet the highest standards it has set for all of its ingredients and menu items. University of Guelph food scientist Ben Bohrer said he does not know how the products that the Marketplace investigation tested were made but he explained what is known as restructured products in the fast food industry. Restructured products are in essence ground meat or smaller pieces of meat that were bound together with other ingredients so they would last longer, taste better, and even cost cheaper. The findings from the Marketplace investigation may be surprising but earlier analyses of food products have revealed an array of DNA that most people do not expect to be present in their food. Last year, California upstart Clear Labs used a molecular analysis technique to test hamburgers and found rat DNA in three samples. It also found human DNA in a frozen vegetarian burger. While these DNA traces may speak something about the quality of the meat products, the report said that these do not pose immediate risk to consumer health. "In general, the presence of human and rat DNA is a potential indicator of low quality and speaks to issues of inconsistent adherence to handling protocols," Clear Labs said. "While we don't consider it a public health concern, it also creates the potential risk for that product to become an outlier as the industry shifts towards greater transparency and more stringent quality standards." © 2017 Tech Times, All rights reserved. Do not reproduce without permission.
Olefeldt D.,McGill University |
Olefeldt D.,University of Guelph |
Roulet N.T.,McGill University
Global Change Biology | Year: 2014
Permafrost thaw in peatlands has the potential to alter catchment export of dissolved organic carbon (DOC) and thus influence downstream aquatic C cycling. Subarctic peatlands are often mosaics of different peatland types, where permafrost conditions regulate the hydrological setting of each type. We show that hydrological setting is key to observed differences in magnitude, timing, and chemical composition of DOC export between permafrost and nonpermafrost peatland types, and that these differences influence the export of DOC of larger catchments even when peatlands are minor catchment components. In many aspects, DOC export from a studied peatland permafrost plateau was similar to that of a forested upland catchment. Similarities included low annual export (2-3 g C m-2) dominated by the snow melt period (~70%), and how substantial DOC export following storms required wet antecedent conditions. Conversely, nonpermafrost fens had higher DOC export (7 g C m-2), resulting from sustained hydrological connectivity during summer. Chemical composition of catchment DOC export arose from the mixing of highly aromatic DOC from organic soils from permafrost plateau soil water and upland forest surface horizons with nonaromatic DOC from mineral soil groundwater, but was further modulated by fens. Increasing aromaticity from fen inflow to outlet was substantial and depended on both water residence time and water temperature. The role of fens as catchment biogeochemical hotspots was further emphasized by their capacity for sulfate retention. As a result of fen characteristics, a 4% fen cover in a mixed catchment was responsible for 34% higher DOC export, 50% higher DOC concentrations and ~10% higher DOC aromaticity at the catchment outlet during summer compared to a nonpeatland upland catchment. Expansion of fens due to thaw thus has potential to influence landscape C cycling by increasing fen capacity to act as biogeochemical hotspots, amplifying aquatic C cycling, and increasing catchment DOC export. © 2014 John Wiley & Sons Ltd.
Van Drunen W.E.,University of Guelph |
Van Kleunen M.,University of Konstanz |
Dorken M.E.,Trent University
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015
Clonality is a pervasive feature of sessile organisms, but this form of asexual reproduction is thought to interfere with sexual fitness via the movement of gametes among the modules that comprise the clone. This within-clone movement of gametes is expected to reduce sexual fitness via mate limitation of male reproductive success and, in some cases, via the production of highly inbred (i.e., self-fertilized) offspring. However, clonality also results in the spatial expansion of the genetic individual (i.e., genet), and this should decrease distances gametes and sexually produced offspring must travel to avoid competing with other gametes and offspring from the same clone. The extent to which any negative effects of clonality on mating success might be offset by the positive effects of spatial expansion is poorly understood. Here, we develop spatially explicit models in which fitness was determined by the success of genets through their male and female sex functions. Our results indicate that clonality serves to increase sexual fitness when it is associated with the outward expansion of the genet. Our models further reveal that the main fitness benefit of clonal expansion might occur through the dispersal of offspring over a wider area compared with nonclonal phenotypes. We conclude that, instead of interfering with sexual reproduction, clonal expansion should often serve to enhance sexual fitness. © 2015, National Academy of Sciences. All rights reserved.
Fraser E.D.G.,University of Leeds |
Fraser E.D.G.,University of Guelph
Ecological Economics | Year: 2011
Although many of today's ecological, climatic and socio-economic problems seem unprecedented, similar events have occurred in the past. As such, historic periods of climatic and economic volatility can be used as a way of developing frameworks for analyzing today's predicament. Western Europe's "middle ages" (circa 11-14th century) may be one such case. By the 12th century, medieval Europe had shifted from the subsistence agrarian economy that emerged following the collapse of the Roman Empire to one where spatially dispersed trade in agricultural commodities helped support a complex society that devoted considerable resources to cultural works. This shift was facilitated by new institutional arrangements centred on monastic orders that provided access to both new agricultural and food processing technologies as well as trade routes. These institutional arrangements contributed to population growth and land clearing. All of these factors increased the wealth of society but also concentrated this wealth in a small number of communities that were dependent on an ever-increasing and exploited hinterland for resources. Ultimately, this created a tightly coupled continent-wide subsistence system that was vulnerable to the weather, economic and disease shocks of the 14th century when Europe's population declined by perhaps 50%. In exploring this history, the goal of this paper is to draw on a diverse theoretical body of literature (that includes resiliency theory, landscape ecology, political science and ecological economics) to develop a series of hypotheses about how large-scale complex civilizations can become vulnerable to climate change. © 2010 Elsevier B.V.
Dantzer B.,Michigan State University |
Dantzer B.,University of Cambridge |
Newman A.E.M.,University of Guelph |
Boonstra R.,University of Toronto |
And 5 more authors.
Science | Year: 2013
In fluctuating environments, mothers may enhance the fitness of their offspring by adjusting offspring phenotypes to match the environment they will experience at independence. In free-ranging red squirrels, natural selection on offspring postnatal growth rates varies according to population density, with selection favoring faster-growing offspring under high-density conditions. We show that exposing mothers to high-density cues, accomplished via playbacks of territorial vocalizations, led to increased offspring growth rates in the absence of additional food resources. Experimental elevation of actual and perceived density induced higher maternal glucocorticoid levels, and females with naturally or experimentally increased glucocorticoids produced offspring that grew faster than controls. Therefore, social cues reflecting population density were sufficient to elicit increased offspring growth through an adaptive hormone-mediated maternal effect.
Turgeon K.,McGill University |
Turgeon K.,University of Guelph |
Kramer D.L.,McGill University
Journal of Animal Ecology | Year: 2012
1.Populations experiencing localized mortality can recover in the short term by net movement of individuals from adjacent areas, a process called compensatory immigration or spillover. Little is known about the factors influencing the magnitude of compensatory immigration or its impact on source populations. Such information is important for understanding metapopulation dynamics, the use of protected areas for conservation, management of exploited populations and pest control. 2.Using two small, territorial damselfish species (Stegastes diencaeus and S. adustus) in their naturally fragmented habitat, we quantified compensatory immigration in response to localized mortality, assessed its impact on adjacent source populations and examined the importance of potential immigrants, habitat quality and landscape connectivity as limiting factors. On seven experimental sites, we repeatedly removed 15% of the initial population size until none remained and immigration ceased. 3.Immigrants replaced 16-72% of original residents in S. diencaeus and 0-69% in S. adustus. The proportion of the source population that immigrated into depleted areas varied from 9% to 61% in S. diencaeus and from 3% to 21% in S. adustus. In S. diencaeus, compensatory immigration was strongly affected by habitat quality, to a lesser extent by the abundance of potential immigrants and not by landscape connectivity. In S. adustus, immigration was strongly affected by the density of potential migrants and not by habitat quality and landscape connectivity. On two control sites, immigration in the absence of creation of vacancies was extremely rare. 4.Immigration occurred in response to localized mortality and was therefore compensatory. It was highly variable, sometimes producing substantial impacts on both depleted and source populations. The magnitude of compensatory immigration was influenced primarily by the availability of immigrants and by the potential improvement in territory quality that they could achieve by immigrating and not by their ability to reach the depleted area. © 2012 British Ecological Society.
Karim L.,University of Guelph |
Nasser N.,Alfaisal University
IET Communications | Year: 2012
Designing energy efficient and reliable routing protocols for mobility centric applications of wireless sensor network (WSN) such as wildlife monitoring, battlefield surveillance and health monitoring is a great challenge since topology of the network changes frequently. Existing cluster-based mobile routing protocols such as LEACH-Mobile, LEACH-Mobile-Enhanced and CBR-Mobile consider only the energy efficiency of the sensor nodes. However, reliability of routing protocols by incorporating fault tolerance scheme is significantly important to identify the failure of data link and sensor nodes and recover the transmission path. Most existing mobile routing protocols are not designed as fault tolerant. These protocols allocate extra timeslots using time division multiple access (TDMA) scheme to accommodate nodes that enter a cluster because of mobility and thus, increases end-to-end delay. Moreover, existing mobile routing protocols are not location aware and assume that sensor nodes know their coordinates. In this study the authors, we propose a location-aware and fault tolerant clustering protocol for mobile WSN (LFCP-MWSN) that is not only energy efficient but also reliable. LFCP-MWSN also incorporates a simple range free approach to localise sensor nodes during cluster formation and every time a sensor moves into another cluster. Simulation results show that LFCP-MWSN protocol has about 25-30% less network energy consumptions and slightly less end-to-end data transmission delay than the existing LEACH-Mobile and LEACH-Mobile-Enhanced protocols. © 2012 The Institution of Engineering and Technology.
Tran A.X.,University of Guelph |
Dong C.,University of St. Andrews |
Whitfield C.,University of St. Andrews
Journal of Biological Chemistry | Year: 2010
LptC is a conserved bitopic inner membrane protein from Escherichia coli involved in the export of lipopolysaccharide from its site of synthesis in the cytoplasmic membrane to the outer membrane. LptC forms a complex with the ATP-binding cassette transporter, LptBFG, which is thought to facilitate the extraction of lipopolysaccharide from the inner membrane and release it into a translocation pathway that includes the putative periplasmic chaperone LptA. Cysteine modification experiments established that the catalytic domain of LptC is oriented toward the periplasm. The structure of the periplasmic domain is described at a resolution of 2.2-Å from x-ray crystallographic data. The periplasmic domain of LptC consists of a twisted boat structure with two β-sheets in apposition to each other. The β-sheets contain seven and eight antiparallel β-strands, respectively. This structure bears a high degree of resemblance to the crystal structure of LptA. Like LptA, LptC binds lipopolysaccharide in vitro. In vitro, LptA can displace lipopolysaccharide from LptC (but not vice versa), consistent with their locations and their proposed placement in a unidirectional export pathway. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.
Ford J.D.,McGill University |
Pearce T.,University of Guelph
Environmental Research Letters | Year: 2010
This letter systematically reviews and synthesizes scientific and gray literature publications (n = 420) to identify and characterize the nature of climate change vulnerability in the Inuvialuit Settlement Region of the western Canadian Arctic and identify gaps in understanding. The literature documents widespread evidence of climate change, with implications for human and biophysical systems. Adaptations are being employed to manage changing conditions and are indicative of a high adaptive capacity. However, barriers to adaptation are evident and are expected to constrain adaptive capacity to future climate change. Continued climate change is predicted for the region, with differential exposure sensitivity for communities, groups and sectors: a function of social-economic-biophysical characteristics and projected future climatic conditions. Existing climate risks are expected to increase in magnitude and frequency, although the interaction between projected changes and socio-economic-demographic trends has not been assessed. The capacity for adapting to future climate change has also not been studied. The review identifies the importance of targeted vulnerability research that works closely with community members and other stakeholders to address research needs. Importantly, the fully categorized list of reviewed references accompanying this letter will be a valuable resource for those working or planning to work in the region, capturing climate change research published since 1990. At a broader level, the systematic review methodology offers a promising tool for climate/environmental change studies in general where there is a large and emerging body of research but limited understanding of research gaps and needs. © 2010 IOP Publishing Ltd.
Ford J.D.,McGill University |
Pearce T.,University of Guelph
Canadian Geographer | Year: 2012
The last decade has witnessed a proliferation of research into the human dimensions of climate change in the Arctic. Much of this work has examined impacts on subsistence hunting, fishing, and trapping among Canadian Inuit communities. This scholarship has developed a baseline understanding of vulnerability and adaptation, drawing upon interviews with community members and stakeholders to identify and characterize climatic risks and adaptive strategies. To further advance this baseline understanding, new methodologies are needed to complement existing research if we are to capture the dynamic nature of how climate change is experienced and responded to, and fully engage communities as equal partners. Longitudinal studies, community-based monitoring, and targeted adaptation research offer significant promise to advance understanding. These methodologies provide a strong basis for developing meaningful partnerships with communities, the co-production of knowledge, and empowerment for adaptation: essential components of community-based participatory research. © Canadian Association of Geographers/L'Association canadienne des géographes.
Zhu L.,McGill University |
Jiang R.,McGill University |
Aoudjit L.,McGill University |
Jones N.,University of Guelph |
Takano T.,McGill University
Journal of the American Society of Nephrology | Year: 2011
Proper organization of the actin cytoskeleton is essential for the normal structure and function of podocytes. RhoA modulates actin dynamics but its role in podocyte biology is controversial. Here, we generated transgenic mice that express a constitutively active form of RhoA in a podocyte-specific and doxycycline-inducible manner. Induction of activated RhoA with doxycycline resulted in significant albuminuria. Furthermore, both the degree of albuminuria and the histologic changes in the glomerulus positively correlated with the level of constitutively active RhoA expression: low levels of expression associated with segmental foot-process effacement without changes observable by light microscopy, whereas higher levels of expression associated with both extensive foot-process effacement and histologic features of focal segmental glomerulosclerosis (FSGS). In addition, induction of activated RhoA markedly upregulated glomerular mRNA expression of fibronectin and collagen IA1, and the degree of upregulation positively correlated with the level of albuminuria. Withdrawal of doxycycline led to a decline in albuminuria toward basal levels in most mice, but heavy albuminuria persisted in some mice. Taken together, these data suggest that activation of RhoA in podocytes leads to albuminuria accompanied by a range of histologic changes characteristic of minimal change disease and FSGS in humans. Although most changes are reversible, severe and prolonged activation of RhoA may cause irreversible glomerulosclerosis. Copyright © 2011 by the American Society of Nephrology.
Olefeldt D.,McGill University |
Olefeldt D.,University of Guelph |
Roulet N.T.,McGill University
Journal of Geophysical Research: Biogeosciences | Year: 2012
Loss of permafrost can modify the export and composition of dissolved organic carbon (DOC) from subarctic peatlands by changing the hydrological regime and altering ecosystem structure and function. In Stordalen peatland complex (68.20N, 19.03E) recent permafrost thaw has caused a conversion of the palsa parts (an ombrotrophic, permafrost affected peatland type) into both bog and flow-through fen peatland types. Within the Stordalen peatland complex we estimated the DOC mass balance and assessed DOC composition for one palsa catchment, one bog catchment and two fens in order to assess the possible impacts of permafrost thaw on peatland complex DOC export. The fens were found to have higher net DOC export rates at 8.1 and 7.0 g C m-2 yr -1 than either the palsa or bog catchments, at 3.2 and 3.5 g C m -2 yr-1, respectively. The snowmelt period was more important for the annual DOC export from the palsa and bog catchments than for the fens, representing 65-100% of the palsa and bog catchment exports while 35-60% of the net fen exports. DOC exported from the palsa and bog catchments were characterized by high aromaticity, molecular weight, C/N ratios, and contained DOC of primarily terrestrial origin. The fens exhibited a shift in DOC composition between inflows and outflows that suggested that fens act as catchment locations for degradation and transformation of DOC. Permafrost thaw can thus alter the magnitude, timing, and composition of subarctic peatland DOC exports due to interactions among peatland type, permafrost conditions, and hydrological setting. Copyright © 2012 by the American Geophysical Union.
Lewis S.P.,University of Guelph |
Heath N.L.,McGill University |
Sornberger M.J.,McGill University |
Arbuthnott A.E.,University of Guelph
Journal of Adolescent Health | Year: 2012
Purpose: To examine viewers' comment responses to nonsuicidal self-injury (NSSI) YouTube videos to determine the potential risks (e.g., NSSI continuation) and benefits (e.g., recovery-oriented social support) of the videos. Methods: Viewers' comments from the 100 most-viewed NSSI videos on YouTube were examined using two coding rubrics, one for the global nature of comments and one for recovery-oriented themes. Both rubrics were developed using an inductive (bottom-up) approach and had high coding inter-rater reliability (exceeding.80 in all cases). For the global nature of comments, 869 randomly selected comments were evaluated using the rubric, which included 8 coding categories and 22 subcategories. For the examination of recovery-oriented themes, self-disclosure comments (n = 377) were evaluated for nature of recovery statements. Results: Results revealed that the most frequent comments were self-disclosure comments in which individuals shared their own NSSI experiences (38.39%), followed by feedback for the video uploader, including admiration of the video quality (21.95%) or message (17.01%), and admiration for the uploader (15.40%) or encouragement to the video uploader (11.15%). Evaluation of the common self-disclosure comments for recovery-oriented content revealed that the majority did not mention recovery at all (42.89%) and indicated that they were still self-injuring (34.00%). Positive recovery statements were uncommon. Conclusions: Results suggest that viewers' responses to videos may maintain the behavior (by sharing their own self-injury experiences) and rarely encourage or mention recovery. It is evident that sharing their own experience online is a strong motivator for viewers of NSSI YouTube videos. © 2012 Society for Adolescent Health and Medicine. All rights reserved.
Ziter C.,McGill University |
Macdougall A.S.,University of Guelph
Ecology | Year: 2013
Given the regulatory impact of resources and consumers on plant production, decomposition, and soil carbon sequestration, anthropogenic changes to nutrient inputs and grazing have likely transformed how grasslands process atmospheric CO2. The direction and magnitude of these changes, however, remain unclear in this system, whose soils contain ;20% of the world's carbon pool. Nutrients stimulate production but can also increase tissue palatability and decomposition. Grazing variously affects tissue quality and quantity, decreasing standing biomass, but potentially increasing leaf nutrient concentrations, root production, or investment in tissue defenses that slow litter decay. Here, we quantified individual and interactive impacts of nutrient addition and simulated grazing (mowing) on above-and belowground production, tissue quality, and soil carbon inputs in a western North American grassland with globally distributed agronomic species. Given that nutrients and grazing are often connected with increased root production and higher foliar tissue quality, we hypothesized that these treatments would combine to reduce inputs of recalcitrant-rich litter critical for C storage. This hypothesis was unsupported. Nutrients and defoliation combined to significantly increase belowground production but did not affect root tissue quality. There were no significant interactions between nutrients and defoliation for any measured response. Three years of nutrient addition increased root and shoot biomass by 37% and 23%, respectively, and had no impact on decomposition, resulting in a ;15% increase in soil organic matter and soil carbon. Defoliation triggered a significant burst of short-lived lignin-rich roots, presumably a compensatory response to foliar loss, which increased root litter inputs by 33%. The majority of root and shoot responses were positively correlated, with aboveground biomass a reasonable proxy for whole plant responses. The exceptions were decomposition, with roots six times more decay resistant, and grazing impacts on tissue chemistry, with shoots undergoing significant alterations, while roots were unaffected. Because neither treatment affected concentrations of decay-resistant compounds in roots, the implied net effect is higher soil C inputs with potentially longer residency times. Areas managed with nutrients and moderate grazing in our study system could thus accumulate significantly more soil C than unmanaged areas, with a greater capacity to serve as sinks for atmospheric CO2. © 2013 by the Ecological Society of America.
Joseph A.E.,University of Guelph |
Skinner M.W.,Trent University
Journal of Rural Studies | Year: 2012
This paper examines voluntarism as a response to the challenges faced by people growing old in rural communities that are themselves being transformed in fundamental ways, both socially and demographically. Informed by evolving theorisations within the rural aging and geographies of voluntarism literatures, we outline the key processes in space and consequent impacts in place that have affected the experience of growing old in rural communities. We identify the changes in service systems that have led to concerns about 'vulnerable people in vulnerable places' and explore this idea in regional contexts ranging from the agricultural heartland to the resource hinterland of Canada. We argue that a distinction needs to be made between the impacts of long and short cycles of change flowing across rural space and attention paid to voluntarism as a critical process at the intersection of broad shifts in service and settlement systems and particular changes in rural communities. Specifically, we suggest that the 'local dynamics of voluntarism' involving the activities of voluntary organisations, community groups and individual volunteers in particular communities can be understood, at once, as a 'barometer of change', a 'mechanism of adjustment' and a 'space of resistance', and we draw on recent case studies of rural voluntarism to illustrate this three-part distinction. In considering the transformative potential of voluntarism for the experience of aging in place, our findings suggest that public discourse, as reflected in media coverage, tends to romanticise voluntarism at the expense of a more nuanced and critical appreciation of its importance to the future of aging rural communities and their elderly residents. The research raises timely questions about academic-versus-popular conceptions of aging in evolving rural spaces and changing rural places. © 2012 Elsevier Ltd.
Gorrell J.C.,University of Alberta |
McAdam A.G.,University of Guelph |
Coltman D.W.,University of Alberta |
Humphries M.M.,McGill University |
Boutin S.,University of Alberta
Nature Communications | Year: 2010
Orphaned animals benefit from being adopted, but it is unclear why an adopting parent should incur the costs of rearing extra young. Such altruistic parental behaviour could be favoured if it is directed towards kin and the inclusive benefits of adoption exceed the costs. Here, we report the occurrence of adoption (five occurrences among 2,230 litters over 19 years) in asocial red squirrels (Tamiasciurus hudsonicus). Adoptions were always between kin, while orphans without nearby kin were never adopted. Adoptions were confined exclusively to circumstances in which the benefits to the adopted juvenile (b), discounted by the degree of relatedness between the surrogate and the orphan (r), exceeded the fitness costs of adding an extra juvenile to her litter (c), as predicted by Hamilton's rule (rb>c) for the evolution of altruism. By focusing on adoption in an asocial species, our study provides a clear test of Hamilton's rule that explains the persistence of occasional altruism in a natural mammal population. © 2010 Macmillan Publishers Limited. All rights reserved.
University of Arkansas, Texas A&M University and University of Guelph | Date: 2016-11-30
Vaccines comprising TRAP polypeptides and Salmonella enteritidis vectors comprising TRAP polypeptides are provided. The vaccines may also include a CD 154 polypeptide capable of binding to CD40. Also provided are methods of enhancing an immune response against Apicomplexan parasites and methods of reducing morbidity associated with infection with Apicomplexan parasites.
University of Arkansas, Texas A&M University and University of Guelph | Date: 2015-02-16
Vaccines comprising TRAP polypeptides and Salmonella enteritidis vectors comprising TRAP polypeptides are provided. The vaccines may also include a CD 154polypeptide capable of binding to CD40. Also provided are methods of enhancing an immune response against Apicomplexan parasites and methods of reducing morbidity associated with infection with Apicomplexan parasites.
News Article | February 15, 2017
The hagfish's successful use of its defense gel is remarkable, particularly because the animal exerts no direct control over the concentration of the slime it exudes into the seawater. Gaurav Chaudhary, a doctoral candidate in the department of mechanical science and engineering at the University of Illinois at Urbana-Champaign (UIUC), will present his work on hagfish slime during the 88th Annual Meeting of The Society of Rheology, being held Feb. 12-16, in Tampa, Florida. The research explores the hagfish's slime formation and the special properties allowing it to assemble into a solid gel without dissolving into the surrounding water. To do this, Chaudhary and his colleagues visited the University of Guelph in Canada, where Professor Doug Fudge maintains a large stock of hagfish. "We obtained raw slime material directly from live fish and then were able to produce our own slime samples of varying concentrations," said Chaudhary. The researchers used a rheometer, which measures the response of such unusual viscosity fluids to forces, to measure how the slime stretched and flowed over time and under various conditions. The research team, led by Randy Ewoldt, an assistant professor who runs the Ewoldt Research Group at UIUC, discovered that the slime's solid- and liquid-like properties remain "self-similar" for a wide range of concentrations. This means that even though the concentration may change dramatically, the general structure and properties of the gel will not. "The gel becomes stiffer with concentration," Ewoldt said. Their results also show that the consistency in how the slime deforms and flows exists because the slime has a similar structure at all concentrations. "We now know that this material, 10,000 times softer than Gelatin, isn't just an ultra-soft elastic solid as earlier believed," Chaudhary said. "Rather, it has very interesting time-dependent properties. Its concentration-dependent properties are very different compared with many other biopolymer or synthetic systems. Such properties make slime distinctly ideal for assembling under uncontrolled conditions." Slime has a myriad of potential applications. For example, it could plug or slow leaks from oil drilling equipment, or provide cell cultures with a sparse network of fibrous elements that may offer unique tissue scaffolds architectures and even support 3-D cell cultures. "Our future efforts will focus on gaining a better understanding of the mechanics of the slime's microstructural level," Chaudhary said. "We'd eventually like to develop materials to achieve similar functionality as hagfish slime by using synthetic components, and further develop ideas and methods to better engineer the material." Explore further: Hagfish slime as a model for tomorrow's natural fabrics More information: Network formation in an infinite sea of water: Concentration-dependent rheology of hagfish defense gel. www.rheology.org/SoR172/ViewPaper?ID=189
Pound A.,University of Southampton |
Carbotte J.P.,McMaster University |
Carbotte J.P.,Canadian Institute for Advanced Research |
Nicol E.J.,University of Guelph
Physical Review B - Condensed Matter and Materials Physics | Year: 2012
We show how coupling to an Einstein phonon ω E affects the absorption peaks seen in the optical conductivity of graphene under a magnetic field B. The energies and widths of the various lines are shifted, and additional peaks arise in the spectrum. Some of these peaks are Holstein sidebands, resulting from the transfer of spectral weight in each Landau level (LL) into phonon-assisted peaks in the spectral function. Other additional absorption peaks result from transitions involving split LLs, which occur when a LL falls sufficiently close to a peak in the self-energy. We establish the selection rules for the additional transitions and characterize the additional absorption peaks. For finite chemical potential, spectral weight is asymmetrically distributed about the Dirac point; we discuss how this causes an asymmetry in the transitions due to left- and right-handed circularly polarized light and therefore oscillatory behavior in the imaginary part of the off-diagonal Hall conductivity. We also find that the semiclassical cyclotron resonance region is renormalized by an effective-mass factor but is not directly affected by the additional transitions. Last, we discuss how the additional transitions can manifest in broadened, rather than split, absorption peaks due to large scattering rates seen in experiment. © 2012 American Physical Society.
Braukmann T.,University of Toronto |
Kuzmina M.,University of Toronto |
Kuzmina M.,University of Guelph |
Stefanovic S.,University of Toronto
Journal of Experimental Botany | Year: 2013
The genus Cuscuta (Convolvulaceae, the morning glory family) is one of the most intensely studied lineages of parasitic plants. Whole plastome sequencing of four Cuscuta species has demonstrated changes to both plastid gene content and structure. The presence of photosynthetic genes under purifying selection indicates that Cuscuta is cryptically photosynthetic. However, the tempo and mode of plastid genome evolution across the diversity of this group (~200 species) remain largely unknown. A comparative investigation of plastid genome content, grounded within a phylogenetic framework, was conducted using a slot-blot Southern hybridization approach. Cuscuta was extensively sampled (~56% of species), including groups previously suggested to possess more altered plastomes compared with other members of this genus. A total of 56 probes derived from all categories of protein-coding genes, typically found within the plastomes of flowering plants, were used. The results indicate that two clades within subgenus Grammica (clades 'O' and 'K') exhibit substantially more plastid gene loss relative to other members of Cuscuta. All surveyed members of the 'O' clade show extensive losses of plastid genes from every category of genes typically found in the plastome, including otherwise highly conserved small and large ribosomal subunits. The extent of plastid gene losses within this clade is similar in magnitude to that observed previously in some non-asterid holoparasites, in which the very presence of a plastome has been questioned. The 'K' clade also exhibits considerable loss of plastid genes. Unlike in the 'O' clade, in which all species seem to be affected, the losses in clade 'K' progress phylogenetically, following a pattern consistent with the Evolutionary Transition Series hypothesis. This clade presents an ideal opportunity to study the reduction of the plastome of parasites 'in action'. The widespread plastid gene loss in these two clades is hypothesized to be a consequence of the complete loss of photosynthesis. Additionally, taxa that would be the best candidates for entire plastome sequencing are identified in order to investigate further the loss of photosynthesis and reduction of the plastome within Cuscuta. © 2013 The Authors.
April J.,Laval University |
Hanner R.H.,University of Guelph |
Dion-Cote A.-M.,Laval University |
Bernatchez L.,Laval University
Molecular Ecology | Year: 2013
Allopatric speciation may be the principal mechanism generating new species. Yet, it remains difficult to judge the generality of this process because few studies have provided evidence that geographic isolation has triggered the development of reproductive isolation over multiple species of a regional fauna. Here, we first combine results from new empirical data sets (7 taxa) and published literature (9 taxa) to show that the eastern Great Lakes drainage represents a multispecies suture zone for glacial lineages of freshwater fishes with variable levels of genetic divergence. Second, we performed amplified fragment length polymorphism analyses among four pairs of lineages. Results indicate that lineages with relatively deep levels of mtDNA 5′ COI (barcode) sequence divergence (>2%) developed strong reproductive barriers, while lineages with lower levels of divergence show weaker reproductive isolation when found in sympatry. This suggests that a threshold of 2% sequence divergence at mtDNA could be used as a first step to flag cryptic species in North American freshwater fishes. By describing different levels of divergence and reproductive isolation in different co-occurring fishes, we offer strong evidence that allopatric speciation has contributed significantly to the diversification of north-eastern American freshwater fishes and confirm that Pleistocene glacial cycles can be viewed as a 'speciation pump' that played a predominant role in generating biodiversity. © 2012 Blackwell Publishing Ltd.
Agatha S.,University of Salzburg |
Struder-Kypke M.C.,University of Guelph
Acta Protozoologica | Year: 2014
The evolution of the dominant marine plankton ciliates, the oligotrichids and choreotrichids, is analysed for morphologic and genetic convergences and apomorphies based on literature and our own data. These findings have taxonomic implications. Within the oli-gotrichid genus Parallelostrombidium two subgenera, Parallelostrombidium Agatha, 2004 nov. stat. and Asymptokinetum nov. subgen., are established, using the courses of the ventral and girdle kineties as a distinguishing feature. Likewise, a different arrangement of extrusome attachment sites is used for a split of the oligotrichid genus Novistrombidium into the subgenera Novistrombidium Song and Bradbury, 1998 nov. stat. and Propecingulum nov. subgen.; Novistrombidium (Propecingulum) ioanum (Lynn and Gilron, 1993) nov. comb. and Novistrombidium (Propecingulum) platum (Song and Packroff, 1997) nov. comb. are affiliated. Based on discrepancies in the somatic ciliary pattern and the presence of conspicuous argyrophilic inclusions, the aloricate choreotrichid species Pelagostrobilidium kimae nov. spec. is distinguished from P. conicum. The diagnosis for the tintinnid family Eutintinnidae Bachy et al., 2012 is improved by including cell features. The co-operation of taxonomists and molecular biologists is strongly recommended to prevent misinterpretations of gene trees due to incorrectly identified species and for better species circumscriptions.
Carbotte J.P.,McMaster University |
Carbotte J.P.,Canadian Institute for Advanced Research |
Nicol E.J.,University of Guelph |
Sharapov S.G.,NASU Bogolyubov Institute for Theoretical Physics
Physical Review B - Condensed Matter and Materials Physics | Year: 2010
We calculate the effect of the electron-phonon interaction on the electronic density of states (DOS), the quasiparticle properties, and on the optical conductivity of graphene. In metals with DOS constant on the scale of phonon energies, the electron-phonon renormalizations drop out of the dressed DOS, however, due to the Dirac nature of the electron dynamics in graphene, the band DOS is linear in energy and phonon structures remain, which can be emphasized by taking an energy derivative. There is a shift in the chemical potential and in the position in energy of the Dirac point. Also, the DOS can be changed from a linear dependence out of value zero at the Dirac point to quadratic out of a finite value. The optical scattering rate 1/τ sets the energy scale for the rise of the optical conductivity from its universal dc value 4 e2 /πh (expected in the simplest theory when chemical potential and temperature are both 1/2τ) to its universal ac background value (σ0 =π e2 /2h). As in ordinary metals the dc conductivity remains unrenormalized while its ac value is changed. The optical spectral weight under the intraband Drude is reduced by a mass-renormalization factor as is the effective scattering rate. Optical weight is transferred to an Holstein phonon-assisted side band. Due to Pauli blocking the interband transitions are sharply suppressed, but also nearly constant, below twice the value of renormalized chemical potential and also exhibit a phonon-assisted contribution. The universal background conductivity is reduced below σ0 at large energies. © 2010 The American Physical Society.
Perera N.,University of Guelph |
Gharabaghi B.,University of Guelph |
Howard K.,University of Toronto
Journal of Hydrology | Year: 2013
Chloride from road salt enters streams primarily through surface runoff and groundwater discharge. Monitoring of dry-weather flow chloride concentrations in the Highland Creek watershed of the eastern Greater Toronto Area indicates the presence of a previously unrecognised, dual porosity aquifer system whereby preferential flow associated with " urban karst" exerts a significant influence on baseflow chloride concentrations early in the year. A chloride mass balance undertaken annually over four successive salting seasons suggests that as much as 40% of the chloride applied as road salt enters the shallow aquifer resulting in a net accumulation of chloride and a gradual increase in mean baseflow chloride concentrations. Assuming current road salt application rates are continued, late summer baseflow chloride concentrations will reach around 505. mg/L, almost double present levels. Elevated chloride concentrations can affect the potability of water (the Canadian aesthetic drinking water quality guideline for chloride is 250. mg/L) and can also be toxic to aquatic organisms (CCME aquatic chronic toxicity guideline is 208. mg/L). Meeting these guidelines would require that the release of salt-laden runoff to the subsurface be reduced by over 50%. © 2012 Elsevier B.V.
Huemer P.,Tiroler Landesmuseen Betriebsgesellschaft m.b.H. |
Hebert P.D.N.,University of Guelph
Zootaxa | Year: 2011
The taxonomy of Sattleria, a genus restricted to European high mountain systems, is critically revised based on morphology, DNA barcodes and phylogeography. Adult morphology combined with sequence information for the barcode region of COI supports the existence of 14 species. The full 658bp fragment of COI was obtained from 43 specimens representing 11 species and three shorter sequences were obtained from another two species. An illustrated key to the male genitalia of all species is provided. Three new species are described: Sattleria karsholti sp. nov. (Alpi Orobie, Adamello and Monte Baldo, Prov. Bergamo, Trento and Verona, Italy), Sattleria cottiella sp. nov. (Cottian Alps, Prov. Cuneo, Italy), and Sattleria graiaeella sp. nov. (Alpi Graie, Prov. Aosta, Italy; Savoie, France). Sattleria basistrigella Huemer, 1997 bona sp., stat. rev. is raised from subspecies rank of Sattleria triglavica Povolný, 1987 to species rank. Copyright © 2011 Magnolia Press.
Espie G.S.,University of Toronto |
Kimber M.S.,University of Guelph
Photosynthesis Research | Year: 2011
Cyanobacteria (as well as many chemoautotrophs) actively pump inorganic carbon (in the form of HCO3 -) into the cytosol in order to enhance the overall efficiency of carbon fixation. The success of this approach is dependent upon the presence of carboxysomes-large, polyhedral, cytosolic bodies which sequester ribulose 1,5- bisphosphate carboxylase/oxygenase (RubisCO) and carbonic anhydrase. Carboxysomes seem to function by allowing ready passage of HCO3 - into the body, but hindering the escape of evolved CO2, promoting the accumulation of CO2 in the vicinity of RubisCO and, consequently, efficient carbon fixation. This selectivity is mediated by a thin shell of protein, which envelops the carboxysome's enzymatic core and uses narrow pores to control the passage of small molecules. In this review, we summarize recent advances in understanding the organization and functioning of these intriguing, and ecologically very important molecular machines. © Springer Science+Business Media B.V. 2011.
Turko A.J.,University of Guelph |
Earley R.L.,University of Alabama |
Wright P.A.,University of Guelph
Animal Behaviour | Year: 2011
The self-fertilizing mangrove rivulus, Kryptolebias marmoratus, can produce homozygous 'clonal' offspring and are highly tolerant of severe environmental conditions, including air exposure (emersion) for weeks at a time. We tested the following hypotheses: (1) individual fish that voluntarily emerse more possess gill and skin features better suited for life on land than fish that emerse less often, and (2) individual differences in emersion tendencies cause these morphological changes. We predicted that individuals spending more time in air would have a reduced gill surface area (shorter, thicker gill lamellae and well developed interlamellar cell masses (ILCM)) and a thicker cutaneous epidermis compared to fish preferring to remain in water. These differences were predicted to disappear if fish were prevented from emersing and predicted to reappear if fish were once again allowed to emerse. Fish were videorecorded for 7 days while voluntarily moving between aquatic and terrestrial habitats to determine individual emersion tendencies. We prevented a subset of fish from emersing for 7 days, and then allowed a subset of these fish to emerse for a final 7 days. We found that individual fish spent anywhere from 0 to 78% of the time emersing. Emersion time was positively correlated with gill ILCM height, but not with any other morphological feature. There was no relationship between ILCM height and emersion time after fish were prevented from emersing for 7 days, but this relationship reappeared when fish were once again able to emerse. These results indicate that genetically identical K. marmoratus show highly variable behavioural phenotypes that influence gill remodelling. Fish that voluntarily spend more time emersed reduce gill surface area, a modification that may limit branchial water loss and provide support for gill lamellae. This is the first report of respiratory morphologies linked to variation in behavioural phenotype. © 2011 The Association for the Study of Animal Behaviour.
Kikkert J.,University of Guelph |
Berkelaar E.,Redeemer University College
Archives of Environmental Contamination and Toxicology | Year: 2013
Selenium (Se) plays a role in human health: It is an essential trace element but can be toxic if too much is consumed. The aim of this study was to determine which species of Se are most rapidly taken up and translocated to above-ground plant tissues. Specifically, we wished to determine if organic forms of Se in an exposure solution can contribute to the amount of Se found in shoot tissue. Durum wheat (Triticum turgidum) and spring canola (Brassica napus) were grown hydroponically, and young seedlings were exposed to 0.5 or 5.0 μM Se as selenate, selenite, seleno-methionione, or seleno-cystine for ≤300 min. Canola accumulated more Se than wheat, although the difference depended on Se speciation of the exposure solution. Organic forms of Se were taken up at a greater rate than inorganic forms. When exposed to 5.0 μM Se, the rate of uptake of selenite was 1.5- (canola) or 5-fold (wheat) greater than the rate of uptake of selenate, whereas seleno-methionine was taken up 40- (canola) or 100-fold (wheat) faster and seleno-cystine 2- (wheat) to 20-fold (canola) faster. Plants exposed to seleno-methionine had the highest shoot concentrations of Se even though selenate was more mobile once taken up; in plants exposed to selenate 〉 50 % of accumulated Se was translocated to shoot tissue. Because organic forms of Se (especially selenomethionine) can be readily taken up and translocated to above-ground tissues of wheat and canola, these Se species should be considered when attempting to predict Se accumulation in above-ground plant tissues. © Springer Science+Business Media New York 2013.
Ortega V.A.,University of Guelph |
Lovejoy D.A.,University of Toronto |
Bernier N.J.,University of Guelph
Frontiers in Neuroscience | Year: 2013
Corticotropin-releasing factor (CRF), urotensin I (UI) and serotonin (5-HT) are generally recognized as key regulators of the anorexigenic stress response in vertebrates, yet the proximal effects and potential interactions of these central messengers on food intake in salmonids are not known. Moreover, no study to date in fishes has compared the appetite-suppressing effects of CRF and UI using species-specific peptides. Therefore, the objectives of this study were to (1) assess the individual effects of synthesized rainbow trout CRF (rtCRF), rtUI as well as 5-HT on food intake in rainbow trout, and (2) determine whether the CRF and serotonergic systems interact in the regulation of food intake in this species. Intracerebroventricular (icv) injections of rtCRF and rtUI both suppressed food intake in a dose-related manner but rtUI [ED50 = 17.4 ng/g body weight (BW)] was significantly more potent than rtCRF (ED50 = 105.9 ng/g BW). Co-injection of either rtCRF or rtUI with the CRF receptor antagonist a-hCRF(9-41) blocked the reduction in food intake induced by CRF-related peptides. Icv injections of 5-HT also inhibited feeding in a dose-related manner (ED50 = 14.7 ng/g BW) and these effects were blocked by the serotonergic receptor antagonist methysergide. While the anorexigenic effects of 5-HT were reversed by a-hCRF(9-41) co-injection, the appetite-suppressing effects of either rtCRF or rtUI were not affected by methysergide co-injection. These results identify CRF, UI and 5-HT as anorexigenic agents in rainbow trout, and suggest that 5-HT-induced anorexia may be at least partially mediated by CRF- and/or UI-secreting neurons. © 2013 Ortega, Lovejoy and Bernier.
Vogan P.J.,University of Guelph |
Sage R.F.,University of Toronto
Oecologia | Year: 2012
This study evaluates acclimation of photosynthesis and stomatal conductance in three evolutionary lineages of C3, C3-C4 intermediate, and C4 species grown in the low CO2 and hot conditions proposed to favo r the evolution of C4 photosynthesis. Closely related C3, C3-C4, and C4 species in the genera Flaveria, Heliotropium, and Alternanthera were grown near 380 and 180 μmol CO2 mol-1 air and day/night temperatures of 37/29°C. Growth CO2 had no effect on photosynthetic capacity or nitrogen allocation to Rubisco and electron transport in any of the species. There was also no effect of growth CO2 on photosynthetic and stomatal responses to intercellular CO2 concentration. These results demonstrate little ability to acclimate to low CO2 growth conditions in closely related C3 and C3-C4 species, indicating that, during past episodes of low CO2, individual C3 plants had little ability to adjust their photosynthetic physiology to compensate for carbon starvation. This deficiency could have favored selection for more efficient modes of carbon assimilation, such as C3-C4 intermediacy. The C3-C4 species had approximately 50% greater rates of net CO2 assimilation than the C3 species when measured at the growth conditions of 180 μmol mol-1 and 37°C, demonstrating the superiority of the C3-C4 pathway in low atmospheric CO2 and hot climates of recent geological time. © 2011 Springer-Verlag.
Weaver L.,AquaResource Inc. |
Arnaud E.,University of Guelph
Sedimentary Geology | Year: 2011
A sedimentological investigation of Quaternary sediments in the Waterloo Moraine was conducted to characterize the nature of deformation in stratified sediments in the Kieswetter Holdings Ltd. aggregate quarry, Kitchener, Ontario. Highly deformed interbedded clay, silt, fine- to very coarse-grained sand and granular to cobble gravel is exposed in two sets of contiguous panels. Analysis of the sediment revealed five recognizable stratigraphic units: 1) climbing ripple cross-laminated silt, 2) normally graded cobble gravel, 3) cross-bedded, fine- to coarse-grained sand, 4) interbedded clay, silt and fine- to very coarse-grained sand with granules and 5) crudely channelized interbedded medium- to very coarse-grained sand and granule to pebble gravel. These units suggest rapid deposition and fluctuating energy in a subaqueous environment prior to deformation.Deformation structures include normal faults with offsets ranging from 1 to 50. cm, widespread occurrences of density-driven ductile deformation ranging from 0.5 to 5. cm, open to closed folds (cm to m scale), as well as isolated occurrences of overturned folding ranging in size from 0.5 cm to approximately 1.2 m. Abundant reverse faulting with offsets ranging from 0.5 to 7 cm (average of 2 cm) and widespread occurrences of boudinage, bed attenuation and shear folds ranging in scale from 0.5 to 1.5. m were also observed. The nature and scale of deformation structures suggest complex polyphase deformation of heterogeneous sediments related to rapid sedimentation, sediment gravity flow, active ice deformation and melting of buried ice in a dynamic subaqueous environment. © 2010 Elsevier B.V.
Olefeldt D.,University of Guelph |
Turetsky M.R.,University of Guelph |
Crill P.M.,University of Stockholm |
Mcguire A.D.,U.S. Geological Survey
Global Change Biology | Year: 2013
Methane (CH4) emissions from the northern high-latitude region represent potentially significant biogeochemical feedbacks to the climate system. We compiled a database of growing-season CH4 emissions from terrestrial ecosystems located across permafrost zones, including 303 sites described in 65 studies. Data on environmental and physical variables, including permafrost conditions, were used to assess controls on CH4 emissions. Water table position, soil temperature, and vegetation composition strongly influenced emissions and had interacting effects. Sites with a dense sedge cover had higher emissions than other sites at comparable water table positions, and this was an effect that was more pronounced at low soil temperatures. Sensitivity analysis suggested that CH4 emissions from ecosystems where the water table on average is at or above the soil surface (wet tundra, fen underlain by permafrost, and littoral ecosystems) are more sensitive to variability in soil temperature than drier ecosystems (palsa dry tundra, bog, and fen), whereas the latter ecosystems conversely are relatively more sensitive to changes of the water table position. Sites with near-surface permafrost had lower CH4 fluxes than sites without permafrost at comparable water table positions, a difference that was explained by lower soil temperatures. Neither the active layer depth nor the organic soil layer depth was related to CH4 emissions. Permafrost thaw in lowland regions is often associated with increased soil moisture, higher soil temperatures, and increased sedge cover. In our database, lowland thermokarst sites generally had higher emissions than adjacent sites with intact permafrost, but emissions from thermokarst sites were not statistically higher than emissions from permafrost-free sites with comparable environmental conditions. Overall, these results suggest that future changes to terrestrial high-latitude CH4 emissions will be more proximately related to changes in moisture, soil temperature, and vegetation composition than to increased availability of organic matter following permafrost thaw. © 2012 Blackwell Publishing Ltd.
Taylor C.M.,Tulane University |
Norris D.R.,University of Guelph
Theoretical Ecology | Year: 2010
Migratory animals are comprised of a complex series of interconnected breeding and nonbreeding populations. Because individuals in any given population can arrive from a variety of sites the previous season, predicting how different populations will respond to environmental change can be challenging. In this study, we develop a population model composed of a network of breeding and wintering sites to show how habitat loss affects patterns of connectivity and species abundance. When the costs of migration are evenly distributed, habitat loss at a single site can increase the degree of connectivity (mixing) within the entire network, which then acts to buffer global populations from declines. However, the degree to which populations are buffered depends on where habitat loss occurs within the network: a site that has the potential to receive individuals from multiple populations in the opposite season will lead to smaller declines than a site that is more isolated. In other cases when there are equal costs of migration to two or more sites in the opposite season, habitat loss can result in some populations becoming segregated (disconnected) from the rest of the network. The geographic structure of the network can have a significant influence on relative population sizes of sites in the same season and can also affect the overall degree of mixing in the network, even when sites are of equal intrinsic quality. When a migratory network is widely spaced and migration costs are high, an equivalent habitat loss will lead to a larger decline in global population size than will occur in a network where the overall costs of migration are low. Our model provides an important foundation to test predictions related to habitat loss in real-world migratory networks and demonstrates that migratory networks will likely produce different dynamics from traditional metapopulations. Our results provide strong evidence that estimating population connectivity is a prerequisite for successfully predicting changes in migratory populations. © Springer Science + Business Media B.V. 2009.
Esmailpour A.,University of Toronto |
Nasser N.,University of Guelph
IEEE Transactions on Vehicular Technology | Year: 2011
Broadband wireless communication systems, namely, Worldwide Interoperability for Microwave Access (WiMAX) and Long-Term Evolution (LTE), promise to revolutionize the mobile users wireless experience by offering many of the services and features promised by fourth-generation (4G) wireless systems, such as supporting multimedia services with high data rates and wide coverage area, as well as all-Internet Protocol (IP) with security and quality-of-service (QoS) support. These systems, however, require proficient radio resource management (RRM) schemes to provide the aforementioned features they promise. In this paper, we propose a new framework, which is called dynamic QoS-based bandwidth allocation (DQBA), to support heterogeneous traffic with different QoS requirements in WiMAX networks. The DQBA framework operates as such; it dynamically changes the bandwidth allocation (BA) for ongoing and new arrival connections based on traffic characteristics and service demand. The DQBA aims at maximizing the system capacity by efficiently utilizing its resources and by being fair, practical, and in compliance with the IEEE 802.16 standard specifications. To achieve its objectives, DQBA employs a flexible architecture that combines the following related components: 1) a two-level packet scheduler scheme; 2) an efficient call admission control policy; and 3) a dynamic BA mechanism. Simulation results and comparisons with existing schemes show the effectiveness and strengths of the DQBA framework in delivering promising QoS and being fair to all classes of services in a WiMAX network. © 2011 IEEE.
Tsutsui K.,Waseda University |
Bentley G.E.,University of California at Berkeley |
Bedecarrats G.,University of Guelph |
Osugi T.,Waseda University |
And 2 more authors.
Frontiers in Neuroendocrinology | Year: 2010
Identification of novel neurohormones that regulate the reproductive axis is essential for the progress of neuroendocrinology. The decapeptide gonadotropin-releasing hormone (GnRH) is the primary factor responsible for the hypothalamic control of gonadotropin secretion. Gonadal sex steroids and inhibin modulate gonadotropin secretion via feedback from the gonads, but a neuropeptide that directly inhibits gonadotropin secretion was unknown in vertebrates until 2000 when a hypothalamic dodecapeptide serving this function was discovered in quail. Because of its action on cultured pituitary in quail, it was named gonadotropin-inhibitory hormone (GnIH). GnIH acts on the pituitary and on GnRH neurons in the hypothalamus via a novel G protein-coupled receptor (GPR147). GPR74 may also be a possible candidate GnIH receptor. GnIH decreases gonadotropin synthesis and release, inhibiting gonadal development and maintenance. Melatonin stimulates the expression and release of GnIH via melatonin receptors expressed by GnIH neurons. GnIH actions and interactions with GnRH seem common not only to several avian species, but also to mammals. Thus, GnIH is considered to have an evolutionarily conserved role in controlling vertebrate reproduction, and GnIH homologs have also been identified in the hypothalamus of mammals. As in birds, mammalian GnIH homologs act to inhibit gonadotropin release in several species. More recent evidence in birds and mammals indicates that GnIH may operate at the level of the gonads as an autocrine/paracrine regulator of steroidogenesis and gametogenesis. Importantly, GnIH in birds and mammals appears to act at all levels of the hypothalamo-pituitary-gonadal (HPG) axis, and possibly over different time-frames (minutes-days). Thus, GnIH and its homologs appear to act as key neurohormones controlling vertebrate reproduction. The discovery of GnIH has enabled us to understand and manipulate vertebrate reproduction from an entirely new perspective. © 2010 Elsevier Inc.
Lobo D.,Tufts University |
Solano M.,Tufts University |
Bubenik G.A.,University of Guelph |
Levin M.,Tufts University
Journal of the Royal Society Interface | Year: 2014
A fundamental assumption of today's molecular genetics paradigm is that complex morphology emerges from the combined activity of low-level processes involving proteins and nucleic acids. An inherent characteristic of such nonlinear encodings is the difficulty of creating the genetic and epigenetic information that will produce a given self-assembling complex morphology. This 'inverse problem' is vital not only for understanding the evolution, development and regeneration of bodyplans, but also for synthetic biology efforts that seek to engineer biological shapes. Importantly, the regenerative mechanisms in deer antlers, planarian worms and fiddler crabs can solve an inverse problem: their target morphology can be altered specifically and stably by injuries in particular locations. Here, we discuss the class of models that use pre-specified morphological goal states and propose the existence of a linear encoding of the target morphology, making the inverse problem easy for these organisms to solve. Indeed, many model organisms such as Drosophila, hydra and Xenopus also develop according to nonlinear encodings producing linear encodings of their final morphologies. We propose the development of testable models of regeneration regulation that combine emergence with a top-down specification of shape by linear encodings of target morphology, driving transformative applications in biomedicine and synthetic bioengineering. & 2014 The Author(s) Published by the Royal Society. All rights reserved.
Tunney T.D.,University of Guelph |
McCann K.S.,University of Guelph |
Lester N.P.,Ontario Ministry of Natural Resources |
Lester N.P.,University of Toronto |
And 2 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014
Food webs unfold across a mosaic of micro and macro habitats, with each habitat coupled by mobile consumers that behave in response to local environmental conditions. Despite this fundamental characteristic of nature, research on how climate change will affect whole ecosystems has overlooked (i) that climate warming will generally affect habitats differently and (ii) that mobile consumers may respond to this differential change in a manner that may fundamentally alter the energy pathways that sustain ecosystems. This reasoning suggests a powerful, but largely unexplored, avenue for studying the impacts of climate change on ecosystem functioning. Here, we use lake ecosystems to show that predictable behavioral adjustments to local temperature differentials govern a fundamental structural shift across 54 food webs. Data show that the trophic pathways from basal resources to a cold-adapted predator shift toward greater reliance on a cold-water refuge habitat, and food chain length increases, as air temperatures rise. Notably, cold-adapted predator behavior may substantially drive this decoupling effect across the climatic range in our study independent of warmer-adapted species responses (for example, changes in nearshore species abundance and predator absence). Such modifications reflect a flexible food web architecture that requires more attention from climate change research. The trophic pathway restructuring documented here is expected to alter biomass accumulation, through the regulation of energy fluxes to predators, and thus potentially threatens ecosystem sustainability in times of rapid environmental change.
Green S.R.,University of Guelph |
Carrasco F.,CONICET |
Lehner L.,Perimeter Institute for Theoretical Physics
Physical Review X | Year: 2014
We study the dynamics of a 2 + 1-dimensional relativistic viscous conformal fluid in Minkowski spacetime. Such fluid solutions arise as duals, under the ''gravity/fluid correspondence,'' to 3 + 1-dimensional asymptotically anti-de Sitter (AAdS) black-brane solutions to the Einstein equation. We examine stability properties of shear flows, which correspond to hydrodynamic quasinormal modes of the black brane. We find that, for sufficiently high Reynolds number, the solution undergoes an inverse turbulent cascade to long-wavelength modes. We then map this fluid solution, via the gravity/fluid duality, into a bulk metric. This suggests a new and interesting feature of the behavior of perturbed AAdS black holes and black branes, which is not readily captured by a standard quasinormal mode analysis. Namely, for sufficiently large perturbed black objects (with long-lived quasinormal modes), nonlinear effects transfer energy from short- to long-wavelength modes via a turbulent cascade within the metric perturbation. As long-wavelength modes have slower decay, this transfer of energy lengthens the overall lifetime of the perturbation. We also discuss various implications of this behavior, including expectations for higher dimensions and the possibility of predicting turbulence in more general gravitational scenarios.
Landry P.,University of Guelph |
Poisson E.,University of Guelph |
Poisson E.,University of Toronto
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015
The deformation of a nonrotating body resulting from the application of a tidal field is measured by two sets of Love numbers associated with the gravitoelectric and gravitomagnetic pieces of the tidal field, respectively. The gravitomagnetic Love numbers were previously computed for fluid bodies under the assumption that the fluid is in a strict hydrostatic equilibrium that requires the complete absence of internal motions. A more realistic configuration, however, is an irrotational state that establishes, in the course of time, internal motions driven by the gravitomagnetic interaction. We recompute the gravitomagnetic Love numbers for this irrotational state and show that they are dramatically different from those associated with the strict hydrostatic equilibrium: while the Love numbers are positive in the case of strict hydrostatic equilibrium, they are negative in the irrotational state. Our computations are carried out in the context of perturbation theory in full general relativity and in a post-Newtonian approximation that reproduces the behavior of the Love numbers when the body's compactness is small. © 2015 American Physical Society.
Landry P.,University of Guelph |
Poisson E.,University of Toronto
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015
We construct the external metric of a slowly rotating, tidally deformed material body in general relativity. The tidal forces acting on the body are assumed to be weak and to vary slowly with time, and the metric is obtained as a perturbation of a background metric that describes the external geometry of an isolated, slowly rotating body. The tidal environment is generic and characterized by two symmetric trace-free tidal moments Eab and Bab, and the body is characterized by its mass M, its radius R, and a dimensionless angular-momentum vector χa蠐1. The perturbation accounts for all couplings between χa and the tidal moments. The body's gravitational response to the applied tidal field is measured in part by the familiar gravitational Love numbers K2el and K2mag, but we find that the coupling between the body's rotation and the tidal environment requires the introduction of four new quantities, which we designate as rotational-tidal Love numbers. All these Love numbers are gauge invariant in the usual sense of perturbation theory, and all vanish when the body is a black hole. © 2015 American Physical Society.
Leblanc J.P.F.,University of Guelph |
Carbotte J.P.,McMaster University |
Carbotte J.P.,Canadian Institute for Advanced Research |
Nicol E.J.,University of Guelph
Physical Review B - Condensed Matter and Materials Physics | Year: 2010
We have calculated the Raman B1g and B2g spectra as a function of temperature, as well as doping, for the underdoped cuprates, using a model based on the resonating valence-bond spin liquid. We discuss changes in intensity and peak position brought about by the presence of a pseudogap and the implied Fermi surface reconstruction, which are elements of this model. Signatures of Fermi surface reconstruction are evident as a sharp rise in the doping dependence of the antinodal to nodal peak ratio which occurs below the quantum critical point. The temperature dependence of the B1g polarization can be used to determine if the superconducting gap is limited to the Fermi pocket, as seen in angle-resolved photoemission spectroscopy, or extends beyond. We find that the slope of the linear low-energy B2g spectrum maintains its usual d -wave form, but with an effective gap which reflects the gap amplitude projected on the Fermi pocket. Our calculations capture the main qualitative features revealed in the extensive data set available on the HgBa2 CuO4+δ (Hg-1201) cuprate. © 2010 The American Physical Society.
Tunney T.D.,University of Guelph |
McCann K.S.,University of Guelph |
Lester N.P.,Ontario Ministry of Natural Resources |
Shuter B.J.,Ontario Ministry of Natural Resources |
Shuter B.J.,University of Toronto
Nature Communications | Year: 2012
Macroscopic ecosystem prope