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.
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.
Gariepy T.D.,Agriculture and Agri Food Canada |
Lindsay R.,Public Health Agency of Canada Zoonotic Diseases and Special Pathogens |
Ogden N.,Public Health Agency of Canada |
Gregory T.R.,University of Guelph
Molecular Ecology Resources | Year: 2012
Ticks are among the most important vectors of disease in the Northern Hemisphere, and a better understanding of their feeding behaviour and life cycle is critical to the management and control of tick-borne zoonoses. DNA-based tools for the identification of residual bloodmeals in hematophagous arthropods have proven useful in the investigation of patterns of host use in nature. Using a blind test approach, we challenged the utility of the DNA barcode library for the identification of vertebrate bloodmeals in engorged, field-collected Ixodes scapularis. Universal vertebrate primers for the COI barcode region successfully amplified DNA from the host bloodmeal and only rarely amplified tick DNA. Of the 61 field-collected ticks, conclusive genus- and species-level identification was possible for 72% of the specimens. In all but two cases, barcode-based identification of the bloodmeal was consistent with the morphological identification of the vertebrate host the ticks were collected from. Possible explanations for mismatches or ambiguities are presented. This study validates the utility of the DNA barcode library as a valuable and reliable resource for the identification of unknown bloodmeals in arthropod vectors of disease. Future directions aimed at the refinement of these techniques to gain additional information and to improve the amplification success of digested vertebrate DNA in tick bloodmeals are discussed. © 2012 Blackwell Publishing Ltd.
Yankulov K.,University of Guelph
Nucleus | Year: 2015
Embryonal totipotent cells can produce both embryonic and extraembryonic tissues and can generate whole organisms. In mice this level of genome plasticity is preserved in the 2-cell embryos, but is absent in embryonic cells from later stages of development. Recently it has been demonstrated that totipotent-like cells spontaneously appear in embryonic stem cell cultures and that the depletion of the histone chaperone Chromatin Assembly Factor I (CAF-I) increases the abundance of 2cell-like cells. On the other hand, earlier studies have demonstrated that CAF-I is necessary for epigenetic conversions at the telomeres of S. cerevisiae. This commentary proposes that the absence of CAF-I confers totipotency of embryonic cells and that its activation triggers chromatin changes that reset the epigenome toward cell differentiation. © 2015 Taylor & Francis Group, LLC.
Bauer B.O.,University of British Columbia |
Davidson-Arnott R.G.D.,University of Guelph
Journal of Geophysical Research: Earth Surface | Year: 2014
Vertical profiles of aeolian sediment flux are commonly modeled as an exponential decay of particle (mass) transport with height above the surface. Data from field and wind-tunnel studies provide empirical support for this parameterization, although a large degree of variation in the precise shape of the vertical flux profile has been reported. This paper explores the potential influence of wind unsteadiness and time-varying intensity of transport on the geometry (slope, curvature) of aeolian particle flux profiles. Field evidence from a complex foredune environment demonstrates that (i) the time series of wind and sediment particle flux are often extremely variable with periods of intense transport (referred to herein as sediment "flurries") separated by periods of weak or no transport; (ii) sediment flurries contribute the majority of transport in a minority of the time; (iii) the structure of a flurry includes a "ramp-up" phase lasting a few seconds, a "core" phase lasting a few seconds to many tens of seconds, and a "ramp-down" phase lasting a few seconds during which the system relaxes to a background, low-intensity transport state; and (iv) conditional averaging of flux profiles for flurry and nonflurry periods reveals differences between the geometry of the mean profiles and hence the transport states that produce them. These results caution against the indiscriminate reliance on regression statistics derived from time-averaged sediment flux profiles, especially those with significant flurry and nonflurry periods, when calibrating or assessing the validity of steady state models of aeolian saltation. ©2014. American Geophysical Union. All Rights Reserved.
Allen-Vercoe E.,University of Guelph
Canadian journal of gastroenterology = Journal canadien de gastroenterologie | Year: 2012
A working group from across Canada comprised of clinician and basic scientists, epidemiologists, ethicists, Health Canada regulatory authorities and representatives of major funding agencies (Canadian Institutes of Health Research and the Crohn's and Colitis Foundation of Canada) met to review the current experience with fecal microbial therapy and to identify the key areas of study required to move this field forward. The report highlights the promise of fecal microbial therapy and related synthetic stool therapy (together called 'microbial ecosystems therapeutics') for the treatment of Clostridium difficile colitis and, possibly, other disorders. It identifies pressing clinical issues that need to be addressed as well as social, ethical and regulatory barriers to the use of these important therapies.
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.
Mason G.J.,University of Guelph
Trends in Ecology and Evolution | Year: 2010
Approximately 26 billion animals, spanning over 10 000 species, are kept on farms and in zoos, conservation breeding centers, research laboratories and households. Captive animals are often healthier, longer-lived and more fecund than free-living conspecifics, but for some species the opposite is true. Captivity is a very long way from the ideal 'common garden' often assumed by evolutionary and ecological researchers using data for captive animals. The use of comparative methods to investigate the fundamental biological causes of these species differences would help to improve husbandry and enclosure design, and might even reveal relationships between susceptibilities to poor captive welfare and susceptibilities to anthropogenic threat in the wild. Studies of these species differences could also inspire and facilitate 'evo-mecho' research into the functions of behavioral control mechanisms. © 2010 Elsevier Ltd.
Woo P.T.K.,University of Guelph
Journal of Biomedicine and Biotechnology | Year: 2010
Salmonid cryptobiosis is caused by the haemoflagellate, Cryptobia salmositica. Clinical signs of the disease in salmon (Oncorhynchus spp.) include exophthalmia, general oedema, abdominal distension with ascites, anaemia, and anorexia. The disease-causing factor is a metalloprotease and the monoclonal antibody (mAb-001) against it is therapeutic. MAb-001 does not fix complement but agglutinates the parasite. Some brook charr, Salvelinus fontinalis cannot be infected (Cryptobia-resistant); this resistance is controlled by a dominant Mendelian locus and is inherited. In Cryptobia-resistant charr the pathogen is lysed via the Alternative Pathway of Complement Activation. However, some charr can be infected and they have high parasitaemias with no disease (Cryptobia-tolerant). In infected Cryptobia-tolerant charr the metalloprotease is neutralized by a natural antiprotease, α2 macroglobulin. Two vaccines have been developed. A single dose of the attenuated vaccine protects 100% of salmonids (juveniles and adults) for at least 24 months. Complement fixing antibody production and cell-mediated response in vaccinated fish rise significantly after challenge. Fish injected with the DNA vaccine initially have slight anaemias but they recover and have agglutinating antibodies. On challenge, DNA-vaccinated fish have lower parasitaemias, delayed peak parasitaemias and faster recoveries. Isometamidium chloride is therapeutic against the pathogen and its effectiveness is increased after conjugation to antibodies. Copyright © 2010 Patrick T. K. Woo.
Schattat M.H.,University of Guelph |
Klosgen R.B.,Martin Luther University of Halle Wittenberg
BMC Plant Biology | Year: 2011
Stromules are dynamic tubular structures emerging from the surface of plastids that are filled with stroma. Despite considerable progress in understanding the importance of certain cytoskeleton elements and motor proteins for stromule maintenance, their function within the plant cell is still unknown. It has been suggested that stromules facilitate the exchange of metabolites and/or signals between plastids and other cell compartments by increasing the cytosolically exposed plastid surface area but experimental evidence for the involvement of stromules in metabolic processes is not available. The frequent occurrence of stromules in both sink tissues and heterotrophic cell cultures suggests that the presence of carbohydrates in the extracellular space is a possible trigger of stromule formation. We have examined this hypothesis with induction experiments using the upper epidermis from rosette leaves of Arabidopsis thaliana as a model system.Results: We found that the stromule frequency rises significantly if either sucrose or glucose is applied to the apoplast by vacuum infiltration. In contrast, neither fructose nor sorbitol or mannitol are capable of inducing stromule formation which rules out the hypothesis that stromule induction is merely the result of changes in the osmotic conditions. Stromule formation depends on translational activity in the cytosol, whereas protein synthesis within the plastids is not required. Lastly, stromule induction is not restricted to the plastids of the upper epidermis but is similarly observed also with chloroplasts of the palisade parenchyma.Conclusions: The establishment of an experimental system allowing the reproducible induction of stromules by vacuum infiltration of leaf tissue provides a suitable tool for the systematic analysis of conditions and requirements leading to the formation of these dynamic organelle structures. The applicability of the approach is demonstrated here by analyzing the influence of apoplastic sugar solutions on stromule formation. We found that only a subset of sugars generated in the primary metabolism of plants induce stromule formation, which is furthermore dependent on cytosolic translational activity. This suggests regulation of stromule formation by sugar sensing mechanisms and a possible role of stromules in carbohydrate metabolism and metabolite exchange. © 2011 Schattat and Klösgen; licensee BioMed Central Ltd.
Lundholm J.T.,Saint Marys University, Halifax |
Richardson P.J.,University of Guelph
Journal of Applied Ecology | Year: 2010
1. Current views of anthropogenic environments emphasize the extreme novelty of urban and industrial ecosystems. Proponents of reconciliation ecology argue that we need to use such habitats to conserve biodiversity, given the inadequacy of natural reserve systems.2. Some of the harshest anthropogenic ecosystems may be able to support indigenous biodiversity due to their structural or functional resemblance to natural ecosystems, habitats, or microsites that may be present in the region but not part of the historic ecosystem on a particular site. Here we review recent work that evaluates similarities between urban and industrial ecosystems and natural analogues, and explore the potential for these in reconciliation ecology.3. We find that artificial habitats represent a gradient of ecological novelty which may be independent of the degree of human influence. While hard-surfaced habitats such as walls and quarries are the most investigated artificial analogues (of natural rock pavements and cliffs), there are many other examples spanning a range of habitats in both terrestrial and marine settings. Analogous ecosystems may be present in the region but limits to dispersal can prevent appropriate species from reaching urban or industrial sites, and small differences in abiotic conditions can sometimes prevent colonization by native biota in otherwise similar artificial habitats. We suggest that a search for habitat analogues represents an important principle to guide reconciliation ecology in urban and industrial lands. In constrast, analogous ecosystems may also support pest species that exploit the similarities between anthropogenic habitats and their ancestral habitats.4. Synthesis and applications. Identifying analogous habitats and ecosystems could enhance biodiversity conservation and ecosystem services in anthropogenic environments. Abiotic and biotic differences between artificial analogues and natural systems can be frequently overcome by ecological engineering to make the environment more suitable for native biodiversity, and/or assisted dispersal to allow suitable native organisms to reach appropriate sites within artificial ecosystems. Altering some habitats to become less analogous may help reduce impacts of pest species in urban and industrial areas. © 2010 The Authors. Journal compilation © 2010 British Ecological Society.
Barbut S.,University of Guelph
World's Poultry Science Journal | Year: 2010
The poultry industry has seen significant changes in the methods used to harvest fresh poultry meat over the past four decades. Some of the major changes include a more than four-fold increase in line speed (new plants are designed to process 12,000 broilers per hour), a large increase in the proportion of cut up and deboned meat produced, as well as substantial improvements in sanitation. These advancements have been possible by gaining knowledge in areas such as computer science (e.g. image analysis, on line weighing and tracking), live bird handling (transportation, unloading, stunning), muscle biology (post mortem processes), heat and mass transfer (scalding, chilling), and engineering (machine building, metallurgy). This article includes a general overview of the different steps involved in primary poultry processing and focuses on some of the principles that have been used to achieve greater efficiencies in mechanising the whole process. The focus areas include stunning, electrical stimulation, chilling, and mechanical filleting. These topics will be used to demonstrate the importance of obtaining high meat quality (e.g. fewer downgrades, high water holding, acceptable tenderness and colour) currently demanded by processors as well as consumers. The advantages of in-line-processing will also be highlighted, where improved efficiencies have been achieved by incorporating real-time computerised monitoring and tracking systems. Overall, a comprehensive understanding of the whole process and the integration of the different steps is a challenge that must be met by both the equipment manufacturer and processing plant personnel. Because of the increased complexity of the whole integrated process, it is highly recommended that the processor team up with a very knowledgeable equipment manufacturer who has the technical understanding and experience within all stages of the process (farm gate to fork), to effectively optimise quality, yield, and speed. © 2010 World's Poultry Science Association.
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.
Sneyd L.Q.,University of Guelph
Sustainability (Switzerland) | Year: 2013
This article analyses wild food consumption in urban areas of Cameroon. Building upon findings from Cameroon's Comprehensive Food Security and Vulnerability Analysis (CFSVA) this case study presents empirical data collected from 371 household and market surveys in Cameroonian cities. It employs the UN Special Rapporteur on the Right to Food's framework for understanding challenges related to the availability, accessibility, and adequacy of food. The survey data suggest that many wild/traditional foods are physically available in Cameroonian cities most of the time, including fruits, vegetables, spices, and insects. Cameroonians spend considerable sums of their food budget on wild foods. However, low wages and the high cost of city living constrain the social and economic access most people have to these foods. The data also suggest that imports of non-traditional staple foods, such as low cost rice, have increasingly priced potentially more nutritious or safe traditional local foods out of markets after the 2008 food price crisis. As a result, diets are changing in Cameroon as the resource-constrained population continues to resort to the coping strategy of eating cheaper imported foods such as refined rice or to eating less frequently. Cameroon's nutrition transition continues to be driven by need and not necessarily by the preferences of Cameroonian consumers. The implications of this reality for sustainability are troubling. © 2013 by the authors; licensee MDPI, Basel, Switzerland.
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.
Sharom F.J.,University of Guelph
Essays in Biochemistry | Year: 2011
Pgp (P-glycoprotein) (ABCB1) is an ATP-powered efflux pump which can transport hundreds of structurally unrelated hydrophobic amphipathic compounds, including therapeutic drugs, peptides and lipid-like compounds. This 170 kDa polypeptide plays a crucial physiological role in protecting tissues from toxic xenobiotics and endogenous metabolites, and also affects the uptake and distribution of many clinically important drugs. It forms a major component of the blood-brain barrier and restricts the uptake of drugs from the intestine. The protein is also expressed in many human cancers, where it probably contributes to resistance to chemotherapy treatment. Many chemical modulators have been identified that block the action of Pgp, and may have clinical applications in improving drug delivery and treating cancer. Pgp substrates are generally lipid-soluble, and partition into the membrane before the transporter expels them into the aqueous phase, much like a 'hydrophobic vacuum cleaner'. The transporter may also act as a 'flippase', moving its substrates from the inner to the outer membrane leaflet. An X-ray crystal structure shows that drugs interact with Pgp within the transmembrane regions by fitting into a large flexible binding pocket, which can accommodate several substrate molecules simultaneously. The nucleotide-binding domains of Pgp appear to hydrolyse ATP in an alternating manner; however, it is still not clear whether transport is driven by ATP hydrolysis or ATP binding. Details of the steps involved in the drug-transport process, and how it is coupled to ATP hydrolysis, remain the object of intensive study. © 2011 Biochemical Society.
Leblanc S.,University of Guelph
Journal of Reproduction and Development | Year: 2010
There is much debate about possible antagonism between high milk production and reproductive performance. This paper reviews methods of measuring reproductive performance and the association of the level of milk production with pregnancy rate at the herd and individual levels. The main question is whether fertility (the capacity for reproductive function and successful pregnancy) of dairy cows has in fact declined, as opposed to the success of management systems and people at meeting the metabolic, nutritional, housing, and social needs of increasingly productive animals but with no less inherent capacity to achieve and maintain pregnancy; and if fertility really has diminished, the extent to which this decline is caused by increased milk production. There is no doubt that production per cow has increased, but it is unclear how much of this increase can explain the apparent decrease in fertility. It is important to separate the biology of reproductive function from the effects of economically based management decisions about culling and continuation of breeding. Most traditionally-used measures of reproductive performance (calving interval, conception rate, non-return rate) are incomplete or severely biased outcome measures. Both herd and cow-level data should include as much information as possible on confounders of the relationship of production with reproduction. Population or herd-level data should not be used to make inferences about individuallevel associations. Considering the quality of data and analytic methods in the published literature, it is not clear if there is any association between higher milk yield and the probability and timing of pregnancy, either among cows at various levels of production in a population at one time, or with increasing production over time.
DeVries T.J.,University of Guelph
Canadian Journal of Animal Science | Year: 2010
There has recently been a significant increase in the amount of scientific research relating dairy cattle behaviour to nutritional management, particularly with respect to the interaction with health. Much of this research has been focused on using information on the natural behavioural patterns of dairy cattle to improve management practices. As with calves and mature dairy cattle, the behaviour of growing replacement dairy heifers interacts with various nutritional management practices. For replacement dairy heifers, much of the research in this area has been focused on how these interactions relate to different feed delivery methods, the amount of feed provided, and stocking density at the feed bunk. This review describes empirical work focused on understanding how nutritional management practices affect heifer behaviour, and how these practices may affect the health, productivity, and welfare of these animals. In particular, evidence will be provided for those practices (such as total mixed ration feeding, feeding for ad libitum intake, and reducing feed bunk competition) that promote feeding behaviour patterns related to more consistent nutrient intake and improved rumen health. Even though the behavioural effects of these nutritional practices are known, additional research is still needed to further demonstrate the possible physiological consequences (e.g., rumen pH, growth rate) of these changes in behaviour. This information is needed so that further recommendations can be made on these practices so these animals may be raised for maximum production potential, while maintaining their behavioural needs, health and overall welfare.
Leblanc S.,University of Guelph
Journal of Reproduction and Development | Year: 2010
This paper reviews the importance of energy metabolism in transition dairy cows, its associations with disease and reproduction, and strategies for monitoring cows under field conditions during this critical time. Essentially all dairy cattle experience a period of insulin resistance, reduced feed intake, negative energy balance, hypocalcemia, reduced immune function, and bacterial contamination of the uterus soon before, or in the weeks after calving. One-third of dairy cows may be affected by some form of metabolic or infectious disease in early lactation. Routine, proactive actions, observations, or analysis are intended to accurately and efficiently provide early detection of problems, to provide an opportunity for investigation and intervention in order to limit the consequences and costs of health problems and reduced animal performance or welfare. Methods of early detection include monitoring of disease and culling records, feed intake, milk production, body condition, and simple metabolic tests. Methods, strategies, and interpretation of measurement of peripartum concentrations of non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHB) as indicators of aspects of energy status and disease risk are reviewed. High NEFA (> 0.4 mmol/l) in the last 7 to 10 days before expected calving is associated with increased risk of displaced abomasum (DA), retained placenta, culling before 60 days in milk, and less milk production in the first 4 months of lactation. Subclinical ketosis (serum BHB > 1200 to 1400 μmol/l) in the first or second week after calving is associated with increased risk of DA, metritis, clinical ketosis, endometritis, prolonged postpartum anovulation, increased severity of mastitis, and lower milk production in early lactation. There are several validated and practical tools for cow-side measurement of ketosis.
Defersha F.M.,University of Guelph |
Chen M.,Concordia University at Montreal
International Journal of Advanced Manufacturing Technology | Year: 2012
Lot streaming is the technique of splitting a given job into sublots to allow the overlapping of successive operations in multi-stage manufacturing systems thereby reducing production makespan. Several research articles appeared in literature to solve this problem and most of these studies are limited to pure flowshop environments where there is only a single machine in each stage. On the other hand, because of the applicability of hybrid flowshops in different manufacturing settings, the scheduling of these types of shops is also extensively studied by several authors. However, the issue of lot streaming in hybrid flowshop environment is not well studied. In this paper, we aim to contribute in bridging the gap between the research efforts in flowshop lot streaming and hybrid flowshop scheduling. We propose a mathematical model and a genetic algorithm for the lot streaming problem of several jobs in multi-stage flowshops where at each stage there are unrelated parallel machines. The jobs may skip some of the stages, and therefore, the considered system is a complex generalized flowshop. The proposed genetic algorithm is executed on both sequential and parallel computing platforms. Numerical examples showed that the parallel implementation greatly improved the computational performance of the developed heuristic. © 2011 Springer-Verlag London Limited.
Jung J.,Dongguk University |
Yi S.,University of Guelph
Addiction Research and Theory | Year: 2014
Although compulsive buying has been predominantly viewed as the chronic need to manage negative affective states, other emotions, such as positive affect and boredom, have also been reported to precede buying lapses among compulsive buyers. The main objectives of this article were to: (1) empirically examine the centrality of the frequent experience of negative affect prior to buying lapses in compulsive buying, and (2) assess the heterogeneity of compulsive buyers based on the frequency of experiencing negative affect, boredom, and positive affect that precede buying lapses. To examine these issues, we used survey data provided by individuals with excessive buying tendencies (N=419). Latent profile analysis of the frequency of the three types of affective states extracted three clusters of buyers: (1) the "escape seeker" cluster with a strong propensity to buy in excess in negative emotions, (2) the "excitement seeker" cluster that reported having lapsed when feeling boredom more frequently than negative affect, and (3) the "low affect management buyer" cluster whose frequency of experiencing the three types of emotions was lower than the other clusters. The majority of escape seekers and excitement seekers exceeded the diagnostic cut-off for compulsive buying. Clinical implications of the findings are also discussed. © 2014 Informa UK Ltd. All rights reserved: reproduction in whole or part not permitted.
Blackadar C.B.,University of Guelph
World Journal of Clinical Oncology | Year: 2016
In the early 1900s, numerous seminal publications reported that high rates of cancer occurred in certain occupations. During this period, work with infectious agents produced only meager results which seemed irrelevant to humans. Then in the 1980s ground breaking evidence began to emerge that a variety of viruses also cause cancer in humans. There is now sufficient evidence of carcinogenicity in humans for human T-cell lymphotrophic virus, human immunodeficiency virus, hepatitis B virus, hepatitis C virus, human papillomavirus, Epstein-Barr virus, and human herpes virus 8 according to the International Agency for Research on Cancer (IARC). Many other causes of cancer have also been identified by the IARC, which include: Sunlight, tobacco, pharmaceuticals, hormones, alcohol, parasites, fungi, bacteria, salted fish, wood dust, and herbs. The World Cancer Research Fund and the American Institute for Cancer Research have determined additional causes of cancer, which include beta carotene, red meat, processed meats, low fibre diets, not breast feeding, obesity, increased adult height and sedentary lifestyles. In brief, a historical review of the discoveries of the causes of human cancer is presented with extended discussions of the difficulties encountered in identifying viral causes of cancer. © 2016 Baishideng Publishing Group Inc. All rights reserved.
Preuss K.E.,University of Guelph
Coordination Chemistry Reviews | Year: 2014
The so-called "metal-radical approach" to the design of molecule-based magnetic materials relies on the availability of paramagnetic ligands that can reliably form coordination complexes with paramagnetic metal ions. While the most common radical ligands are based on nitroxides, other paramagnetic building blocks are also gaining attention. Thiazyls and their related selenazyls are promising candidates for the development of radical ligands and, because they have inherently interesting materials' properties, their use as ligands has the potential to generate novel materials with unprecedented properties. Significant progress has been made in this field in the past ten years. This review is a timely look back at the development of the field, highlighting the diversity of complexes and designs, and a look forward to a promising future. © 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.
Farazdaghi H.,University of Guelph
BioSystems | Year: 2011
Photosynthesis is the origin of oxygenic life on the planet, and its models are the core of all models of plant biology, agriculture, environmental quality and global climate change. A theory is presented here, based on single process biochemical reactions of Rubisco, recognizing that: In the light, Rubisco activase helps separate Rubisco from the stored ribulose-1,5-bisphosphate (RuBP), activates Rubisco with carbamylation and addition of Mg 2+, and then produces two products, in two steps: (Step 1) Reaction of Rubisco with RuBP produces a Rubisco-enediol complex, which is the carboxylase-oxygenase enzyme (Enco) and (Step 2) Enco captures CO 2 and/or O 2 and produces intermediate products leading to production and release of 3-phosphoglycerate (PGA) and Rubisco. PGA interactively controls (1) the carboxylation-oxygenation, (2) electron transport, and (3) triosephosphate pathway of the Calvin-Benson cycle that leads to the release of glucose and regeneration of RuBP. Initially, the total enzyme participates in the two steps of the reaction transitionally and its rate follows Michaelis-Menten kinetics. But, for a continuous steady state, Rubisco must be divided into two concurrently active segments for the two steps. This causes a deviation of the steady state from the transitional rate. Kinetic models are developed that integrate the transitional and the steady state reactions. They are tested and successfully validated with verifiable experimental data. The single-process theory is compared to the widely used two-process theory of Farquhar et al. (1980. Planta 149, 78-90), which assumes that the carboxylation rate is either Rubisco-limited at low CO 2 levels such as CO 2 compensation point, or RuBP regeneration-limited at high CO 2. Since the photosynthesis rate cannot increase beyond the two-process theory's Rubisco limit at the CO 2 compensation point, net photosynthesis cannot increase above zero in daylight, and since there is always respiration at night, it leads to progressively negative daily CO 2 fixation with no possibility of oxygenic life on the planet. The Rubisco-limited theory at low CO 2 also contradicts all experimental evidence for low substrate reactions, and for all known enzymes, Rubisco included. © 2010 Elsevier Ireland Ltd.
Woodward B.,University of Guelph
International Journal of Molecular Sciences | Year: 2016
Inflammatory incompetence is characteristic of acute pediatric protein-energy malnutrition, but its underlying mechanisms remain obscure. Perhaps substantially because the research front lacks the driving force of a scholarly unifying hypothesis, it is adrift and research activity is declining. A body of animal-based research points to a unifying paradigm, the Tolerance Model, with some potential to offer coherence and a mechanistic impetus to the field. However, reasonable skepticism prevails regarding the relevance of animal models of acute pediatric malnutrition; consequently, the fundamental contributions of the animal-based component of this research front are largely overlooked. Design-related modifications to improve the relevance of animal modeling in this research front include, most notably, prioritizing essential features of pediatric malnutrition pathology rather than dietary minutiae specific to infants and children, selecting windows of experimental animal development that correspond to targeted stages of pediatric immunological ontogeny, and controlling for ontogeny-related confounders. In addition, important opportunities are presented by newer tools including the immunologically humanized mouse and outbred stocks exhibiting a magnitude of genetic heterogeneity comparable to that of human populations. Sound animal modeling is within our grasp to stimulate and support a mechanistic research front relevant to the immunological problems that accompany acute pediatric malnutrition. © 2016 by the author; licensee MDPI, Basel, Switzerland.
Levison H.F.,Southwest Research Institute |
Thommes E.,University of Guelph |
Duncan M.J.,Queens University
Astronomical Journal | Year: 2010
One of the most challenging problems we face in our understanding of planet formation is how Jupiter and Saturn could have formed before the solar nebula dispersed. The most popular model of giant planet formation is the so-called core accretion model. In this model a large planetary embryo formed first, mainly by two-body accretion. This is then followed by a period of inflow of nebular gas directly onto the growing planet. The core accretion model has an Achilles heel, namely the very first step. We have undertaken the most comprehensive study of this process to date. In this study, we numerically integrate the orbits of a number of planetary embryos embedded in a swarm of planetesimals. In these experiments, we have included a large number of physical processes that might enhance accretion. In particular, we have included (1) aerodynamic gas drag, (2) collisional damping between planetesimals, (3) enhanced embryo cross sections due to their atmospheres, (4) planetesimal fragmentation, and (5) planetesimal-driven migration. We find that the gravitational interaction between the embryos and the planetesimals leads to the wholesale redistribution of material - regions are cleared of material and gaps open near the embryos. Indeed, in 90% of our simulations without fragmentation, the region near those embryos is cleared of planetesimals before much growth can occur. Thus, the widely used assumption that the surface density distribution of planetesimals is smooth can lead to misleading results. In the remaining 10% of our simulations, the embryos undergo a burst of outward migration that significantly increases growth. On timescales of 105 years, the outer embryo can migrate 6 AU and grow to roughly 30 M ⊕. This represents a largely unexplored mode of core formation. We also find that the inclusion of planetesimal fragmentation tends to inhibit growth except for a narrow range of fragment migration rates. © 2010. The American Astronomical Society.
Di Mauro F.M.,University of Guelph
Journal of veterinary emergency and critical care (San Antonio, Tex. : 2001) | Year: 2013
Acetylsalicylic acid (ie, aspirin) administration inhibits platelet aggregation in dogs and is associated with increased perioperative blood loss and transfusion requirements in people. Desmopressin acetate (DDAVP) is used to control or prevent bleeding in dogs with type 1 von Willebrand disease and is also widely reported in the human literature as an emergency antithrombotic reversal agent. Three dogs undergoing surgery for intervertebral disc disease had marked prolongations in buccal mucosal bleeding time (BMBT) after aspirin administration. DDAVP was given intravenously preoperatively and achieved prompt reversal of the prolongation in BMBT. None of the dogs experienced intraoperative bleeding complications. IV DDAVP corrected prolongations in BMBT in dogs given aspirin and should be considered in dogs requiring prompt reversal of aspirin-induced coagulopathies to reduce the risk of bleeding complications. © Veterinary Emergency and Critical Care Society 2013.
Nonogaki H.,Oregon State University |
Bassel G.W.,University of Nottingham |
Bewley J.D.,University of Guelph
Plant Science | Year: 2010
Germination is a complex process during which the seed must quickly recover physically from maturation drying, resume a sustained intensity of metabolism, complete essential cellular events to allow for the embryo to emerge, and prepare for subsequent seedling growth. Early following the start of imbibition of the dry seed there is re-establishment of metabolism; restitution of the chemical and structural integrity of cells requires the co-participation of synthetic and protective events. Protein synthesis and respiratory activity initially involve components stored within the mature dry seed, although transcription and translation commence early during imbibition, as shown by transciptome and metabolome analyses. Increases or modifications to hormones, especially GA, play an important role in achieving the completion of germination, at least in intact seeds. Removal or deactivation of ABA is also important; interactions between this and GA play a regulatory role. A restraint on the completion of germination in seeds of some species is imposed by the surrounding structures, e.g. the endosperm, and thus there is a requirement either for it to be enzymically weakened to allow the radicle to emerge, or for sufficient force to be generated within the embryo axis to physically break through, or both. While there is much information with respect to changes in gene expression during germination, no key event(s) has been identified that results in its completion. The downstream effects of the observed hormone changes are not known, and given the multipart nature of the seed, the requirements imposed upon it (repair, maintenance, preparation for seedling growth) in addition to completing germination (which involves only a limited number of cells), the challenge to identify 'germination-completion' genes is large. Hence there are limited opportunities at present for improving germination through genetic manipulation. © 2010 Elsevier Ireland Ltd.
Acevedo N.C.,Iowa State University |
Marangoni A.G.,University of Guelph
Annual Review of Food Science and Technology | Year: 2015
A new understanding of the nature and organization of fat crystalline supramolecular structure, in particular at the nanoscale, has arisen in the past three years. These new findings have helped establish that the first step in the formation of a triacylglycerol network is the creation of nanocrystalline platelets that aggregate into polycrystalline clusters in the micrometer range, ultimately forming a three-dimensional network. This review explains how fat nanostructure can be characterized and highlights recent findings on how crystallization parameters influence the formation of fat nanocrystals. For instance, shear has been shown to modify not only nanoplatelet size but also their aggregation, affecting some macroscopic properties such as porosity and, therefore, the ability of the network to effectively bind liquid oil. This new information on fat nanostructure is relevant from scientific and technological standpoints and has opened up the possibility of nanoengineering material properties as well as developing new products and processes. Copyright ©2015 by Annual Reviews. All rights reserved.
Manderville R.A.,University of Guelph |
Wetmore S.D.,University of Lethbridge
Chemical Science | Year: 2016
Aryl radical species derived from enzymatic transformations of aromatic mutagens preferentially react at the 8-site of the guanine (G) nucleobase to afford carbon-linked 8arylG adducts. The resulting lesions possess altered biophysical and genetic coding properties compared to the precursor G nucleoside in B-form DNA. Unlike other adducts, these lesions also possess useful fluorescent properties, since direct attachment of the 8aryl ring extends the purine π-system to afford G mimics with red-shifted excitation maxima and emission that can be sensitive to the microenvironment of the 8arylG base within nucleic acid structures. In B-form DNA, 8arylG adducts are disruptive to duplex formation because they prefer to adopt the syn-conformation about the bond connecting the nucleobase to the deoxyribose backbone, which perturbs Watson-Crick (WC) H-bonding with the opposing cytosine (C). Thus, in a B-form duplex, the emissive properties of 8arylG adducts can be employed as a tool to provide insight into adduct conformation, which can be related to their biological outcomes. However, since Gs preferentially adopt the syn-conformation in left-handed Z-DNA and antiparallel G-quadruplex (GQ) structures, 8arylG lesions can be inserted into syn-G positions without disrupting H-bonding interactions. In fact, 8arylG lesions can serve as ideal fluorescent probes in an antiparallel GQ because their emission is sensitive to GQ folding. This perspective outlines recent developments in the biological implications of 8arylG formation together with their utility as fluorescent G analogs for use in DNA-based diagnostic systems. © The Royal Society of Chemistry 2016.
Silver J.J.,University of Guelph
Journal of Rural Studies | Year: 2013
This article interrogates shellfish aquaculture expansion efforts and outcomes in British Columbia (BC), Canada. While the clearest objectives of the Provincial Government's 1998 Shellfish Development Initiative were to privatize new ocean tenures and increase the wholesale value of the BC shellfish aquaculture sector, the analysis identifies and explores a range of government-led and government-funded interventions that emerged to discipline coastal space and subjects accordingly. These include: classifying productive space and projecting economic potential; identifying beneficiaries and enrolling Indigenous First Nations entrepreneurs; and, generating supportive knowledge, practice and public relations. I argue that these efforts work to produce 'new shellfish growing regions' imagined to be homogeneously ideal for shellfish aquaculture. They also reinforce the notion that coastal residents, especially First Nations, must adopt very specific outlooks and practices before the sector's full economic potential can be met. Theorizing these processes in terms of neoliberalization provides important perspective at a time when aquaculture is being widely promoted for its potential as an approach to economic modernization and sustainability in coastal communities in BC and beyond. © 2013 Elsevier Ltd.
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..
Caswell J.L.,University of Guelph
Veterinary Pathology | Year: 2014
The respiratory system is well defended against inhaled bacteria by a dynamic system of interacting layers, including mucociliary clearance, host defense factors including antimicrobial peptides in the epithelial lining fluid, proinflammatory responses of the respiratory epithelium, resident alveolar macrophages, and recruited neutrophils and monocytes. Nevertheless, these manifold defenses are susceptible to failure as a result of stress, glucocorticoids, viral infections, abrupt exposure to cold air, and poor air quality. When some of these defenses fail, the lung can be colonized by bacterial pathogens that are equipped to evade the remaining defenses, resulting in the development of pneumonia. This review considers the mechanisms by which these predisposing factors compromise the defenses of the lung, with a focus on the development of bacterial pneumonia in cattle and supplemented with advances based on mouse models and the study of human disease. Deepening our understanding of how the respiratory defenses fail is expected to lead to interventions that restore these dynamic immune responses and prevent disease. © The Author(s) 2013.
Weese J.S.,University of Guelph
Equine Veterinary Journal | Year: 2014
Infectious diseases are an important cause of morbidity and mortality in horses, along with economic costs and broader impacts associated with the loss of members of a species that generates income, acts as a working animal and is a companion. Endemic diseases continue to challenge, emerging diseases are an ever-present threat and outbreaks can be both destructive and disruptive. While infectious diseases can never be completely prevented, measures can be introduced to restrict the entry of pathogens into a population or limit the implications of the presence of a pathogen. Objective research regarding infection control and biosecurity in horses is limited, yet a variety of practical infection prevention and control measures can be used. Unfortunately, infection control can be challenging, because of the nature of the equine industry (e.g. frequent horse movement) and endemic pathogens, but also because of lack of understanding or motivation to try to improve practices. Recognition of the basic concepts of infection control and biosecurity, and indeed the need for measures to control infectious diseases, is the foundation for successful infection prevention and control. © 2014 EVJ Ltd.
Chouinard L.E.,University of Guelph
Canadian Journal of Dietetic Practice and Research | Year: 2011
North American family physicians and dietitians commonly recommend psyllium fibre supplementation for treating symptoms of irritable bowel syndrome (IBS). In this review, evidence on the effectiveness of psyllium supplementation for diagnosed IBS symptoms was evaluated and summarized. A systematic search of MEDLINE, CINAHL, and Web of Science was conducted. Included were full-length, peer-reviewed, Englishlanguage articles in which psyllium ingestion was tested for its effect on IBS symptoms. Quality of these articles also was assessed. Twelve met the criteria for complete data abstraction. Seventy-five percent of the studies examined were of weak quality. Study designs and methods were heterogeneous. Patient-perceived global symptoms improved significantly in six of the nine studies measuring a global symptom outcome. In one study, significant improvements occurred in reported abdominal pain; in three, improvement did not occur. Quality of life and flatulence did not improve significantly in any studies in which these outcomes were examined. The results of this systematic review indicate limited and conflicting evidence to support the recommendation of psyllium supplementation for symptomatic IBS treatment.
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.
Marshall S.A.,University of Guelph
Zootaxa | Year: 2013
Bregmosina, a new genus of Limosininae (Diptera, Sphaeroceridae), is described on the basis of five new species from Central and South America. The genus is characterized by a broad head, swollen face, large oral cavity, a single pair of very large cruciate interfrontal bristles, short, broad fore tarsomeres and swollen hind tarsomeres one and two. The unusual male genitalia, including a longitudinally split sternite 5, strongly indicate that the genus is monophyletic. All species are probably associated with treefalls. Copyright © 2013 Magnolia Press.
Trevors J.T.,University of Guelph
Current issues in molecular biology | Year: 2011
During his famous 1943 lecture series at Trinity College Dublin, the reknown physicist Erwin Schrodinger discussed the failure and challenges of interpreting life by classical physics alone and that a new approach, rooted in Quantum principles, must be involved. Quantum events are simply a level of organization below the molecular level. This includes the atomic and subatomic makeup of matter in microbial metabolism and structures, as well as the organic, genetic information code of DNA and RNA. Quantum events at this time do not elucidate, for example, how specific genetic instructions were first encoded in an organic genetic code in microbial cells capable of growth and division, and its subsequent evolution over 3.6 to 4 billion years. However, due to recent technological advances, biologists and physicists are starting to demonstrate linkages between various quantum principles like quantum tunneling, entanglement and coherence in biological processes illustrating that nature has exerted some level quantum control to optimize various processes in living organisms. In this article we explore the role of quantum events in microbial processes and endeavor to show that after nearly 67 years, Schrödinger was prophetic and visionary in his view of quantum theory and its connection with some of the fundamental mechanisms of life.
Lubitz W.D.,University of Guelph
Applied Energy | Year: 2011
Hourly typical meteorological year (TMY3) data was utilized with the Perez radiation model to simulate solar radiation on fixed, azimuth tracking and two axis tracking surfaces at 217 geographically diverse temperate latitude sites across the contiguous United States of America. The optimum tilt angle for maximizing annual irradiation on a fixed south-facing panel varied from being equal to the latitude at low-latitude, high clearness sites, to up to 14° less than the latitude at a north-western coastal site with very low clearness index. Across the United States, the optimum tilt angle for an azimuth tracking panel was found to be on average 19° closer to vertical than the optimum tilt angle for a fixed, south-facing panel at the same site. Azimuth tracking increased annual solar irradiation incident on a surface by an average of 29% relative to a fixed south-facing surface at optimum tilt angle. Two axis tracking resulted in an average irradiation increase of 34% relative to the fixed surface. Introduction of manual surface tilt changes during the year produced a greater impact for non-tracking surfaces than it did for azimuth tracking surfaces. Even monthly tilt changes only resulted in an average annual irradiation increase of 5% for fixed panels and 1% for azimuth tracked surfaces, relative to using a single optimized tilt angle in each case. In practice, the decision whether to manually tilt panels requires balancing the added cost in labor and the panel support versus the extra energy generation and the cost value of that energy. A Supplementary spreadsheet file is available that gives individual results for each of the 217 simulated sites. © 2010 Elsevier Ltd.
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.
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.
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.
Becker S.,University of Guelph
Hydrobiologia | Year: 2010
Bioassays with the toxic cyanobacterium Microcystis aeruginosa PCC 7806, its non-toxic mutant ΔmcyB, and Daphnia magna as grazer were used to evaluate biotic factors in induced defence, in particular cyanobacterial and grazer-released info-chemicals. Three main questions were addressed in this study: Does Daphnia grazing lead to a loss of cyanobaterial biomass? Is the survival time of Daphnia shorter in a culture of the toxic cyanobacterium? Does direct grazing or the presence of spent Daphnia medium or a high number of disrupted toxic Microcystis cells in the assays lead to an increase in the cellular microcystin content in the remaining intact cells? The biovolume (growth) as well as size and abundance of Microcystis aggregates were determined by particle analysis, while the survival time of Daphnia individuals was recorded by daily observation and counting, with the relative concentration of cell-bound microcystin-LR, was measured by HPLC analysis. Compared to some recent studies in the field of induced defence, in this study, evidence was found for a direct grazing effect, i.e. the loss of biovolume in the toxic culture. In addition, Daphnia magna ingested more non-toxic than toxic cells, and survived longer with non-toxic cells. In terms of increased cell-bound toxin concentration as a means of defence reported in some studies, a higher cell-bound microcystin-LR content was not measured in this study in any of the treatments (P > 0.05). Under low light conditions with impaired growth of Microcystis, and the presence of a high number of particles with less than 1-μm diameter (possibly heterotrophic bacteria), Daphnia medium was associated with a strong reduction in cell-bound toxin concentration (P < 0.05). This study showed no increased cell aggregation under direct grazing (P > 0.05), but increased aggregation with spent Daphnia medium under high light conditions (P < 0.05). Further, the addition of cell-free extract from disrupted toxic Microcystis cells strongly increased the aggregation of the intact cells under low light (P < 0.05). These findings are discussed with the possible role of microcystin and other infochemicals in the expression of proteins and morphology changes in Microcystis. © Springer Science+Business Media B.V. 2010.
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.
Mahian O.,Ferdowsi University of Mashhad |
Mahmud S.,University of Guelph |
Pop I.,Babes - Bolyai University
International Journal of Heat and Mass Transfer | Year: 2012
In this paper, an analysis of the first and second laws of thermodynamics is presented to show the effects of MHD flow on the distributions of velocity, temperature and entropy generation between two concentric rotating cylinders. The flow inside the gap is assumed to be steady state and laminar for an incompressible, viscous, and Newtonian fluid. The walls of the cylinders are kept at different constant temperatures. Governing equations in cylindrical coordinates are simplified and analytically solved to obtain the local and average (overall) entropy generation rate. Due to the nature of the problem, the velocity distribution in the annulus becomes as the modified Bessel functions I 1(MR) and K 1(MR). Therefore, to obtain the temperature field, the expansions of the modified Bessel functions I 1(MR) and K 1(MR), with 3 terms, are employed in the energy equation. The results are presented for various values of Hartmann number (M), radius ratio (Π), group parameter (Ω/Br), and Brinkman number (Br). © 2012 Elsevier Ltd. All rights reserved.
Humphries M.M.,University of Sainte-Anne |
Mccann K.S.,University of Guelph
Journal of Animal Ecology | Year: 2014
Summary: Ecological theory that is grounded in metabolic currencies and constraints offers the potential to link ecological outcomes to biophysical processes across multiple scales of organization. The metabolic theory of ecology (MTE) has emphasized the potential for metabolism to serve as a unified theory of ecology, while focusing primarily on the size and temperature dependence of whole-organism metabolic rates. Generalizing metabolic ecology requires extending beyond prediction and application of standardized metabolic rates to theory focused on how energy moves through ecological systems. A bibliometric and network analysis of recent metabolic ecology literature reveals a research network characterized by major clusters focused on MTE, foraging theory, bioenergetics, trophic status, and generalized patterns and predictions. This generalized research network, which we refer to as metabolic ecology, can be considered to include the scaling, temperature and stoichiometric models forming the core of MTE, as well as bioenergetic equations, foraging theory, life-history allocation models, consumer-resource equations, food web theory and energy-based macroecology models that are frequently employed in ecological literature. We conclude with six points we believe to be important to the advancement and integration of metabolic ecology, including nomination of a second fundamental equation, complementary to the first fundamental equation offered by the MTE. © 2013 British Ecological 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.
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.
Marks S.,University of Toronto |
Mountjoy M.,University of Guelph |
Marcus M.,York University
British Journal of Sports Medicine | Year: 2012
Sexual harassment and abuse occur in all sports and at all levels with an increased risk at the elite level. The physical and psychological consequences of sexual harassment and abuse are signifi cant for the athlete, their team and for the health and integrity of sport in general. The sports medicine health professional has an integral role to play in the prevention of sexual harassment and abuse in sport. This paper provides sport healthcare professionals with a practical guide on prevention strategies and advice on the recognition and management of suspected abuse.
Pardhan-Ali A.,University of Guelph
BMC public health | Year: 2013
Enteric pathogens are an important cause of illness, however, little is known about their community-level risk factors (e.g., socioeconomic, cultural and physical environmental conditions) in the Northwest Territories (NWT) of Canada. The objective of this study was to undertake ecological (group-level) analyses by combining two existing data sources to examine potential community-level risk factors for campylobacteriosis, giardiasis and salmonellosis, which are three notifiable (mandatory reporting to public health authorities at the time of diagnosis) enteric infections. The rate of campylobacteriosis was modeled using a Poisson distribution while rates of giardiasis and salmonellosis were modeled using a Negative Binomial distribution. Rate ratios (the ratio of the incidence of disease in the exposed group to the incidence of disease in the non-exposed group) were estimated for infections by the three major pathogens with potential community-level risk factors. Significant (p≤0.05) associations varied by etiology. There was increased risk of infection with Salmonella for communities with higher proportions of 'households in core need' (unsuitable, inadequate, and/or unaffordable housing) up to 42% after which the rate started to decrease with increasing core need. The risk of giardiasis was significantly higher both with increased 'internal mobility' (population moving between communities), and also where the community's primary health facility was a health center rather than a full-service hospital. Communities with higher health expenditures had a significantly decreased risk of giardiasis. Results of modeling that focused on each of Giardia and Salmonella infections separately supported and expanded upon previous research outcomes that suggested health disparities are often associated with socioeconomic status, geographical and social mobility, as well as access to health care (e.g. facilities, services and professionals). In the campylobacteriosis model, a negative association was found between food prices in communities and risk of infection. There was also a significant interaction between trapping and consumption of traditional foods in communities. Higher rates of community participation in both activities appeared to have a protective effect against campylobacteriosis. These results raise very interesting questions about the role that traditional activities might play in infectious enteric disease incidence in the NWT, but should be interpreted with caution, recognizing database limitations in collection of case data and risk factor information (e.g. missing data). Given the cultural, socioeconomic, and nutritional benefits associated with traditional food practices, targeted community-based collaborative research is necessary to more fully investigate the statistical correlations identified in this exploratory research. This study demonstrates the value of examining the role of social determinants in the transmission and risk of infectious diseases.
Lewis S.P.,University of Guelph
Journal of Nervous and Mental Disease | Year: 2016
Nonsuicidal self-injury (NSSI) has emerged as a significant mental health concern over the past several years. Accordingly, it is imperative thatmental health professionals be able to draw upon and use approaches that meet the needs of thosewho report NSSI enactment. Notwithstanding the utility inherent in published recommendations for NSSI assessment and intervention, the aspect of NSSI scarring and its potential impact on those who have self-injured seems to be largely overlooked. Indeed, there is emerging evidence that people's perceptions of their NSSI scars may thwart NSSI recovery. This commentary highlights what is currently known about NSSI scarring and its potential impact on individuals who have self-injured. From here, and based on the state of evidence in this nascent area, tentative albeit practical suggestions for assessment and intervention are presented. © Copyright 2015 Wolters Kluwer Health, Inc. All rights reserved.
Luksiene Z.,Vilnius University |
Brovko L.,University of Guelph
Food Engineering Reviews | Year: 2013
Development of novel methods for decontamination of food and food-processing, food-handling environment, which are compatible with the consumer demand for minimally processed safe foods, remains one of the urgent topics of food science. One of these methods-antibacterial photosensitization-based treatment-is gaining more attention recently due to its unique properties. The method is based on combined action of nontoxic dye (called photosensitizer), visible light, and oxygen-producing cytotoxic effect (photodynamic effect). Presently, this method is widely used as anticancer and antiinfections treatments under the name photodynamic therapy. Photosensitization-based treatment was shown to be effective against a wide range of microorganisms (Gram-positive and Gram-negative bacteria in both vegetative form and spores, as well as in biofilms, mammalian viruses and bacteriophages, fungi and yeasts, and parasitic protozoa); no existing or emerging resistance against this treatment was observed even after multiple applications and the possibility of that is considered very unlikely; possibility to initiate the process on-spot and on-demand by targeted delivery of illumination provides multiple treatment options tailored to each particular case. Recent advances in the area of antibacterial photosensitization-based treatment applications in food and food-processing environment are presented in this review. Advantages and shortcomings of the method are discussed. © 2013 Springer Science+Business Media New York.
Chagnon P.-L.,Universite de Sherbrooke |
Bradley R.L.,Universite de Sherbrooke |
Maherali H.,University of Guelph |
Klironomos J.N.,University of British Columbia
Trends in Plant Science | Year: 2013
Despite the growing appreciation for the functional diversity of arbuscular mycorrhizal (AM) fungi, our understanding of the causes and consequences of this diversity is still poor. In this opinion article, we review published data on AM fungal functional traits and attempt to identify major axes of life history variation. We propose that a life history classification system based on the grouping of functional traits, such as Grime's C-S-R (competitor, stress tolerator, ruderal) framework, can help to explain life history diversification in AM fungi, successional dynamics, and the spatial structure of AM fungal assemblages. Using a common life history classification framework for both plants and AM fungi could also help in predicting probable species associations in natural communities and increase our fundamental understanding of the interaction between land plants and AM fungi. © 2013 Elsevier Ltd.
Goldenberg M.J.,University of Guelph
Theoretical Medicine and Bioethics | Year: 2012
As the quality movement in health care now enters its fourth decade, the language of quality is ubiquitous. Practitioners, organizations, and government agencies alike vociferously testify their commitments to quality and accept numerous forms of governance aimed at improving quality of care. Remarkably, the powerful phrase "quality of care" is rarely defined in the health care literature. Instead it operates as an accepted and assumed goal worth pursuing. The status of evidence-based medicine, for instance, hinges on its ability to improve quality of care, and efforts are made by both proponents and detractors to unpack the contents and outcomes of evidence-based practice while the contents of "quality of care" are presumed to be understood. Because the goals of medicine are far from obvious, this paper investigates the neglected term, "quality of care," in an effort to understand what it is that health care practices are so uncritically assumed to be striving for. Finding lack of consensus on the terminology in the quality literature, I propose that the term operates rhetorically by way of persuasive appeal (and lack of descriptive meaning). Unsatisfied that "quality of care" operates as a mere buzzword in morally contentious debates over resource allocation and duties of care, I implore health care communities to go beyond mere commitments to quality and, instead, to focus attention on the difficult task of specifying what counts as quality care within an economically constrained health care system. © 2012 Springer Science+Business Media B.V.
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.
Delaplane K.S.,University of Georgia |
Van Der Steen J.,Wageningen University |
Guzman-Novoa E.,University of Guelph
Journal of Apicultural Research | Year: 2013
This paper covers measures of field colony strength, by which we mean population measures of adult bees and brood. There are generally two contexts in which an investigator wishes to measure colony strength: 1. at the beginning of a study as part of manipulations to produce uniform colonies and reduce experimental error and; 2. as response variables during or at the end of an experiment. Moreover, there are two general modes for measuring colony strength: 1. an objective mode which uses empirical measures and; 2. a subjective mode that relies on visual estimates by one or more observers. There is a third emerging mode for measuring colony strength; 3. computer-assisted digital image analysis. A final section deals with parameters that do not directly measure colony strength yet give important indicators of colony state: flight activity at the hive entrance; comb construction; and two proxy measures of colony fitness: production of queen cells and drone brood. Copyright © IBRA 2013.
Ferguson B.,University of Guelph
Substance Use and Misuse | Year: 2012
This note argues that addiction itself can be seen as a form of double failure, specifically the failure to stick to a predetermined optimal lifetime consumption path for an addictive commodity, which failure might be the result of bad luck, and the failure to adjust the level of consumption of the addictive commodity once the consumer is off their optimal path, which might be seen as a failure of judgment. © 2012 Informa Healthcare USA, Inc.
Fobel R.,University of Toronto |
Fobel R.,Donnelly College |
Fobel C.,University of Guelph |
Wheeler A.R.,University of Toronto |
Wheeler A.R.,Donnelly College
Applied Physics Letters | Year: 2013
We introduce DropBot: an open-source instrument for digital microfluidics (http://microfluidics.utoronto.ca/dropbot). DropBot features two key functionalities for digital microfluidics: (1) real-time monitoring of instantaneous drop velocity (which we propose is a proxy for resistive forces), and (2) application of constant electrostatic driving forces through compensation for amplifier-loading and device capacitance. We anticipate that this system will enhance insight into failure modes and lead to new strategies for improved device reliability, and will be useful for the growing number of users who are adopting digital microfluidics for automated, miniaturized laboratory operation. © 2013 AIP Publishing LLC.
Biglarbegian M.,University of Guelph
Proceedings of the American Control Conference | Year: 2012
This paper presents a rigorous mathematical development for the design of robust intelligent type-2 fuzzy control systems with regards to the disturbance rejection problem. The majority of the papers in the literature uses only type-1 fuzzy systems for the modeling of both plant ant controller. In the control structure presented in this paper, we use type-2 fuzzy systems, which are more generalized than their type-1 counterparts and particularly known for handling uncertainties. This work extends and generalizes the previous results for the design of robust intelligent control systems. The final robust criteria are given based on linear matrix inequalities (LMIs), and two examples are provided to demonstrate the developed methodologies. The simulation results also show the potential of type-2 fuzzy controllers in improving robustness compared to type-1. The mathematically-sound general framework proposed in this paper provides a systematic tool for the design of robust intelligent controllers, and hence it is expected to widen their applications. © 2012 AACC American Automatic Control Council).
Barbut S.,University of Guelph
Meat Science | Year: 2014
The global meat industry has seen significant changes in the methods used to harvest and process fresh meat over the past century. Increased use of automation has led to significant increases in line speed for beef, pork, sheep, poultry and fish operations. For example, currently the fastest line observed has been broilers at 13,500/h. Such developments have required in-depth understanding of the pre and post rigor processes to prevent defects. Procedures such as maturation chilling and electrical stimulation are now common in red meat and poultry processing; allowing shorter time to deboning, while harvesting high quality meat. Robots designed to cut meat are also appearing on the market, and replacing traditional manual operations. This is a challenge, because high speed equipment is not necessarily sensitive to variations in size/quality issues, and requires development of unique sensors and control systems. Also, progress in breeding and genetics is contributing to greater product uniformity and quality; helping in operating automated equipment. © 2013.
Griswold C.K.,University of Guelph
Journal of Theoretical Biology | Year: 2015
Epistatic gene action occurs when mutations or alleles interact to produce a phenotype. Theoretically and empirically it is of interest to know whether gene interactions can facilitate the evolution of diversity. In this paper, we explore how epistatic gene action affects the additive genetic component or heritable component of multivariate trait variation, as well as how epistatic gene action affects the evolvability of multivariate traits. The analysis involves a sexually reproducing and recombining population. Our results indicate that under stabilizing selection conditions a population with a mixed additive and epistatic genetic architecture can have greater multivariate additive genetic variation and evolvability than a population with a purely additive genetic architecture. That greater multivariate additive genetic variation can occur with epistasis is in contrast to previous theory that indicated univariate additive genetic variation is decreased with epistasis under stabilizing selection conditions. In a multivariate setting, epistasis leads to less relative covariance among individuals in their genotypic, as well as their breeding values, which facilitates the maintenance of additive genetic variation and increases a population's evolvability. Our analysis involves linking the combinatorial nature of epistatic genetic effects to the ancestral graph structure of a population to provide insight into the consequences of epistasis on multivariate trait variation and evolution. © 2015 Elsevier Ltd.
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.
Bertoft E.,University of Guelph
Cereal Chemistry | Year: 2013
The molecular structure of the starch components has been a focus of research since it was discovered that starch is transformed into sugar by treatment with acid or barley malt extract in the beginning of the 19th century. Only in 1940 was it definitely recognized that starch contains two glucan polymers, wherein amylose was defined as the linear component and amylopectin as the branched polymer. Since then, the structure of amylopectin has been exhaustively investigated, and during the years several models have been suggested, of which the cluster model has obtained the most acceptance. During the last decade, however, experimental results have been obtained that are not entirely in favor of this model, and an alternative, two-directional backbone model was proposed. This article discusses the latter model and its impact on our understanding of the structure, properties, and synthesis of the starch granule. © 2013 AACC International, Inc.
Dufresne F.,University of Quebec at Rimouski |
Jeffery N.,University of Guelph
Chromosome Research | Year: 2011
The study of genome size diversity is an ever-expanding field that is highly relevant in today's world of rapid and efficient DNA sequencing. Animal genome sizes range from 0.02 to 132.83 pg but the majority of animal genomes are small, with the most of these genome sizes being less than 5 pg. Animals with large genomes (>10 pg) are scattered within some invertebrates, including the Platyhelminthes, crustaceans, and orthopterans, and also the vertebrates including the Actinopterygii, Chondrichthyes, and some amphibians. In this paper, we explore the connections between organismal phenotype, physiology, and ecology to genome size. We also discuss some of the molecular mechanisms of genome shrinkage and expansion obtained through comparative studies of species with full genome sequences and how this may apply to species with large genomes. As most animal species sequenced to date have been in the small range for genome size (especially invertebrates) due to sequencing costs and to difficulties associated with large genome assemblies, an understanding of the structural composition of large genomes is still lacking. Studies using next-generation sequencing are being attempted for the first time in animals with larger genomes. Such analyses using low genome coverage are providing a glimpse of the composition of repetitive elements in animals with more complex genomes. These future studies will allow a better understanding of factors leading to genomic obesity in animals. © 2011 Springer Science+Business Media B.V.
Shokralla S.,University of Guelph
BioTechniques | Year: 2010
DNA extraction is the first step in many molecular biology protocols. However, we hypothesized that DNA from a preserved specimen can leak into its preservative medium, allowing the medium itself to be directly PCR-amplified. We successfully tested this idea on mescal-the alcoholic beverage famous for the "worm" (a caterpillar) that is placed in the bottle of many brands-and indeed obtained amplifiable quantities of caterpillar DNA. We then successfully amplified and sequenced DNA from the 95% ethanol preservative of 70 freshly collected specimens and 7 archival specimens 7-10 years old. These results suggest that DNA extraction is a superfluous step in many protocols and that preservative ethanol can be used as a source of genetic material for non-invasive sampling or when no tissue specimen is left for further DNA analyses.
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.
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.
Brown J.A.,University of Guelph
2012 IEEE Symposium on Computational Intelligence and Computational Biology, CIBCB 2012 | Year: 2012
In this study we look at a novel evolutionary technique known as the multiple worlds model for unsupervised classification of sequences via evolved motifs. This evolutionary algorithm uses the biological inspirations of species and species extinction as features modeled in the evolution in order to provide classifiers where the number of classes is not known a priori. In the multiple worlds model a number of populations which do not interbreed compete in fitness evaluation. Sequence motifs are small, biologically significant DNA/RNA or amino acid segments. They are represented as strings of symbols and wild cards. The model works well to locate classification motifs for sequences whose classes have statistical deviations such as those with a GC content difference or those created from differing Self-Driving Markov models. The creation of such classifiers will allow biologists to examine large sets of sequences in order to discover significant features. © 2012 IEEE.
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
Yang J.,University of Guelph
Environmental Modelling and Software | Year: 2011
Sensitivity analysis plays an important role in model development, calibration, uncertainty analysis, scenario analysis, and, hence, decision making. With the availability of different sensitivity analysis techniques, selecting an appropriate technique, monitoring the convergence and estimating the uncertainty of the sensitivity indices are very crucial for environmental modelling, especially for distributed models due to their high non-linearity, non-monotonicity, highly correlated parameters, and intensive computational requirements. It would be useful to identify whether some techniques outperform others with respect to computational requirements, reliability, and other criteria. This paper proposes two methods to monitor the convergence and estimate the uncertainty of sensitivity analysis techniques. One is based on the central limit theorem and the other on the bootstrap technique. These two methods are implemented to assess five different sensitivity analysis techniques applied to an environmental model. These techniques are: the Sobol' method, the Morris method, Linear Regression (LR), Regionalized Sensitivity Analysis (RSA), and non-parametric smoothing. The results show that: (i) the Sobol' method is very robust in quantifying sensitivities and ranking parameters despite a large number of model evaluations; (ii) the Morris method is efficient to rank out unimportant parameters at a medium cost; (iii) the non-parametric smoothing is reliable and robust in quantifying the main effects and low-order interactions while requiring a small number of model evaluations; finally (iv) the other two techniques, that is, LR and RSA, should be used with care. © 2010 Elsevier Ltd.
Preuss K.E.,University of Guelph
Polyhedron | Year: 2014
The nature of the chemical bond is fundamental to the modern concept of chemistry. Species that exhibit unusual interactions provide a valuable challenge to current theoretical models and computational techniques. One of the areas that has garnered significant interest in the past decade is the computational analysis of so-called "pancake bonds" between planar organic or light-atoms radicals. The present review provides a timely survey of the more common organic and light-atom neutral radicals, radical cations and radical anions that are known to form π-dimers in the solid state. © 2014 Elsevier Ltd. All rights reserved.
Brown R.D.,University of Guelph
Landscape and Urban Planning | Year: 2011
Microclimatic planning and design can ameliorate negative effects of global climate change. Design modifications to outdoor environments can increase thermal comfort, and in extreme cases can be life-saving. This is not work for amateurs, or for professionals using their intuition or personal experiences. This work must be based on scholarly evidence acquired through carefully designed studies, accurate and precise measurements, and appropriate analysis. Built landscapes should be evaluated to determine if they achieved their microclimate modifying objectives, and the resulting information should be used to inform future studies. Methods for incorporating microclimate information in design should be made more user-friendly and accessible to designers, and knowledge about the effects of landscape planning and design on climate should be effectively communicated to decision-makers at all levels. © 2011 Elsevier B.V.
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.
Abell B.M.,Sheffield Hallam University |
Mullen R.T.,University of Guelph
Plant Cell Reports | Year: 2011
Tail-anchored (TA) proteins are special class of integral membrane proteins that in recent years have received a considerable amount of attention due to their diverse cellular functions and unique targeting and insertion mechanisms. Defined by the presence of a single, hydrophobic membrane-spanning domain at or near their C terminus, TA proteins must be inserted into membranes post-translationally and are orientated such that their larger N-terminal domain (most often the functional domain) faces the cytosol, while their shorter C-terminal domain faces the interior of the organelle. The C-terminal domain of TA proteins also usually contains the information responsible for their selective targeting to the proper subcellular membrane, a process that, based primarily on studies with yeasts and mammals, appears to be highly complex due to the presence of multiple pathways. Within this context, we discuss here the biogenesis of plant TA proteins and the potential for hundreds of new TA proteins identified via bioinformatics screens to contribute to the already remarkable number of roles that this class of membrane proteins participates in throughout plant growth and development. © 2010 Springer-Verlag.
Trevors J.T.,University of Guelph
International Journal of Molecular Sciences | Year: 2011
This article discusses the hypothesized composition and organization of cytoplasm in prebiotic cells from a theoretical perspective and also based upon what is currently known about bacterial cytoplasm. It is unknown if the first prebiotic, microscopic scale, cytoplasm was initially contained within a primitive, continuous, semipermeable membrane, or was an uncontained gel substance, that later became enclosed by a continuous membrane. Another possibility is that the first cytoplasm in prebiotic cells and a primitive membrane organized at the same time, permitting a rapid transition to the first cell(s) capable of growth and division, thus assisting with the emergence of life on Earth less than a billion years after the formation of the Earth. It is hypothesized that the organization and composition of cytoplasm progressed initially from an unstructured, microscopic hydrogel to a more complex cytoplasm, that may have been in the volume magnitude of about 0.1-0.2 μm 3 (possibly less if a nanocell) prior to the first cell division. © 2011 by the authors; licensee MDPI, Basel, Switzerland.
Lipkowski J.,University of Guelph
Physical Chemistry Chemical Physics | Year: 2010
This article describes efforts to build a model biological membrane at a surface of a gold electrode. In this architecture, the membrane may be exposed to static electric fields on the order of 10 7 to 10 8 V m -1. These fields are comparable in magnitude to the static electric field acting on a natural biological membrane. The field may be conveniently used to manipulate organic molecules within the membrane. By turning a knob on the control instrument one can deposit or lift the membrane from the gold surface. Electrochemical techniques can be used to control the physical state of the film while the infrared reflection absorption spectroscopy (IRRAS), surface imaging by STM and AFM and neutron scattering techniques can be employed to study conformational changes of organic molecules and their ordering within the membrane. This is shown on examples of membranes built of a simple zwitterionic phospholipid such as 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) and a mixed membrane composed of DMPC and cholesterol. The results illustrate the tremendous effect of cholesterol on the membrane structure. Two methods of membrane deposition at the electrode surface, namely by unilamellar vesicles fusion and using the Langmuir-Blodgett technique, are compared. Applications of these model systems to study interactions of small antibiotic peptides with lipids are discussed. © the Owner Societies 2010.
Babin-Fenske J.,Laurentian University |
Anand M.,University of Guelph
Ecological Modelling | Year: 2011
The forest tent caterpillar (Malacosoma disstria Hübner) (FTC) has an outbreak cycle of approximately 10 years; however, smaller spatial scale analyses show some regions have longer or more frequent periods of high defoliation. This may be a result of local forest fragmentation, pollution or other sources of stress that may affect FTC directly or indirectly through stress on their hosts or parasitoids. Population dynamics of FTC were examined to investigate how stress may alter the severity and frequency of defoliation. We developed a spatially explicit agent-based model to simulate the host-parasitoid dynamics of FTC. Theoretical and empirically derived parameters were established using past literature and over 50 years of population data of FTC from Ontario, Canada. We find that increasing FTC fecundity, FTC dispersal or parasitoid mortality resulted in more severe outbreaks while a decrease in parasitoid fecundity or searching efficiency resulted in an overall elevation of defoliation. Parasitoid efficiency was the most effective parameter for altering the FTC defoliation. Since plant stress has been shown to alter several of these parameters in nature due to changes in food quality, habitat suitability, and chemical cue interference, our results suggest that forests affected by stressors such as climate change and pollution will have more severe and frequent defoliation from these insects than surrounding unaffected forests. As stressors such as drought and pollution emissions are predicted to increase in frequency or intensity over the next few decades, understanding how they may affect the outbreak cycle of a forest defoliator can aid in planning strategies to reduce the detrimental effects of this insect. © 2011 Elsevier B.V.
Goldman S.,University of Guelph
Journal of Chemical Physics | Year: 2010
Thermodynamic expressions are derived for the system relative Gibbs free energy, and the relative Gibbs free energy per bubble, for all possible equilibrium bubble states that can form in a soft slightly rigid material, initially supersaturated with a dissolved inert gas (N2). While the thermodynamic manipulations are exact, the final expressions are approximate, due to an approximation made in deriving the expression for the elastic free energy of a soft material containing more than a single bubble. The expressions predict that provided the shear modulus of the soft material is not negligibly small, free energy wells which stabilize small gas bubbles for finite periods of time exist in such materials. This is consistent with a previous calculation, based solely on the bubble pressure equation, which resulted in the conjecture that bubbles found in soft materials with some rigidity (or shear resistance) are likely to be small. The possible relevance of this to the field of decompression sickness is outlined. © 2010 American Institute of Physics.
Corry R.C.,University of Guelph
Impact Assessment and Project Appraisal | Year: 2011
Wind energy development is expanding. Preparations for wind farms include environmental impact assessments, specifically with visual impact assessments (VIAs). Often using simulated photographs, VIAs depict the post-development landscape appearance with new wind energy structures. This Ontario case study compares simulated photographs submitted as part of a VIA with post-development conditions. Simulations were judged for accuracy in turbine number, height, diameter, and location, and adequacy in representation of built conditions. Simulations were partially representative of postdevelopment conditions, yet commonly under-represented turbine number and size in different locations than they were built. Simulation frames were too narrow to adequately represent human vision and simulations under-estimated how many wind turbines were visible from a single landscape position. Outcomes suggest that visual simulations can lack accuracy or representativeness, misleading the public. Adopting province-wide VIA criteria and increasing adherence to visual simulation guidance may be necessary to improve the accuracy and representativeness of VIA content. © IAIA 2011.
Gherboudj I.,Universite de Sherbrooke |
Magagi R.,Universite 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.
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.
Biglarbegian M.,University of Guelph
Journal of Intelligent and Robotic Systems: Theory and Applications | Year: 2013
To extend the utility of multiple mobile robots (MMRs) in formation on a larger scale, the algorithms developed for control of such robots must be robust. The majority of the developed controllers in the literature lack incorporating dynamics of the MMRs or lack robustness in their design. The very few recently developed robust controllers that consider dynamics, either rely on conservative assumptions to obtain robustness, or are sliding-mode based which suffer from the chattering problem. In this paper, (1) we consider both kinematics and dynamics as well as the actuator dynamics and their uncertainties in formulating the formation of non-holonomic MMRs, (2) we develop a novel robust control technique that can effectively handle the unknown parameters and uncertainties in the system, (3) unlike other papers, we relax the conservative assumptions to arrive at control design, and present rigorous mathematical analyses for the development of robust control and prove the system stability based on the Lyapunov theorem. Simulation results proved the effectiveness of the developed robust control method. It was concluded that the proposed control method, while not being conservative, is easy to use and can be readily adopted in real-time experiments. © 2012 Springer Science+Business Media Dordrecht.
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.
Bonnett B.N.,University of Guelph |
Egenvall A.,Swedish University of Agricultural Sciences
Journal of Comparative Pathology | Year: 2010
From 1995 to the present Agria Animal Insurance, Sweden (Agria Djurförsäkring, Stockholm, Sweden) has provided data on both health care and life insurance claims for descriptive and analytical research. From these data we have published extensively on insured dogs and horses and have recently submitted a study on cat mortality. Over the periods studied most extensively (1995-2002 for dogs, 1997-2004 for horses and 1999-2006 for cats), Agria has insured approximately 200,000 dogs, 100,000 horses and up to 200,000 cats per year. Estimates based on formal research or market surveys suggest that Agria insures approximately 40% of both the Swedish dog and horse populations and 50% of the purebred cat population. Where animal insurance is so widely embraced, the Agria-insured populations are likely to be representative of the national population. This paper focuses on age patterns of disease, differences between breeds and genders, body system and disease process and changes over time. An increase in survival over the years for dogs and cats is undoubtedly affected by owner, societal and veterinary factors relative to the availability of, and willingness and ability to access, and continue, veterinary care. In addition, marked differences in survival across breeds suggest that comparisons between people and companion animals in terms of health, disease and longevity must consider these complexities. © 2009 Elsevier Ltd. All rights reserved.
Xiang Y.,University of Guelph
International Journal of Approximate Reasoning | Year: 2012
To specify a Bayesian network (BN), a conditional probability table (CPT), often of an effect conditioned on its n causes, must be assessed for each node. Its complexity is generally exponential in n. Noisy-OR and a number of extensions reduce the complexity to linear, but can only represent reinforcing causal interactions. Non-impeding noisy-AND (NIN-AND) trees are the first causal models that explicitly express reinforcement, undermining, and their mixture. Their acquisition has a linear complexity, in terms of both the number of parameters and the size of the tree topology. As originally proposed, however, they allow only binary effects and causes. This work generalizes binary NIN-AND tree models to multi-valued effects and causes. It is shown that the generalized NIN-AND tree models express reinforcement, undermining, and their mixture at multiple levels, relative to each active value of the effect. The model acquisition is still efficient. For binary variables, they degenerate into binary NIN-AND tree models. Hence, this contribution enables CPTs of discrete BNs of arbitrary variables (binary or multi-valued) to be specified efficiently through the intuitive concepts of reinforcement and undermining. © 2012 Elsevier Inc. All rights reserved.
Irving J.,University of Lausanne |
Irving J.,University of Guelph |
Singha K.,Pennsylvania State University
Water Resources Research | Year: 2010
Quantifying the spatial configuration of hydraulic conductivity (K) in heterogeneous geological environments is essential for accurate predictions of contaminant transport, but is difficult because of the inherent limitations in resolution and coverage associated with traditional hydrological measurements. To address this issue, we consider crosshole and surface-based electrical resistivity geophysical measurements, collected in time during a saline tracer experiment. We use a Bayesian Markov-chain-Monte-Carlo (McMC) methodology to jointly invert the dynamic resistivity data, together with borehole tracer concentration data, to generate multiple posterior realizations of K that are consistent with all available information. We do this within a coupled inversion framework, whereby the geophysical and hydrological forward models are linked through an uncertain relationship between electrical resistivity and concentration. To minimize computational expense, a facies-based subsurface parameterization is developed. The Bayesian-McMC methodology allows us to explore the potential benefits of including the geophysical data into the inverse problem by examining their effect on our ability to identify fast flowpaths in the subsurface, and their impact on hydrological prediction uncertainty. Using a complex, geostatistically generated, two-dimensional numerical example representative of a fluvial environment, we demonstrate that flow model calibration is improved and prediction error is decreased when the electrical resistivity data are included. The worth of the geophysical data is found to be greatest for long spatial correlation lengths of subsurface heterogeneity with respect to wellbore separation, where flow and transport are largely controlled by highly connected flowpaths. Copyright © 2010 by the American Geophysical Union.
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.
Dumont Y.,CIRAD - Agricultural Research for Development |
Tchuenche J.M.,University of Guelph
Journal of Mathematical Biology | Year: 2012
Chikungunya is an arthropod-borne disease caused by the Asian tiger mosquito, Aedes albopictus. It can be an important burden to public health and a great cause of morbidity and, sometimes, mortality. Understanding if and when disease control measures should be taken is key to curtail its spread. Dumont and Chiroleu (Math Biosc Eng 7(2):315-348, 2010) showed that the use of chemical control tools such as adulticide and larvicide, and mechanical control, which consists of reducing the breeding sites, would have been useful to control the explosive 2006 epidemic in Réunion Island. Despite this, chemical control tools cannot be of long-time use, because they can induce mosquito resistance, and are detrimental to the biodiversity. It is therefore necessary to develop and test new control tools that are more sustainable, with the same efficacy (if possible). Mathematical models of sterile insect technique (SIT) to prevent, reduce, eliminate or stop an epidemic of Chikungunya are formulated and analysed. In particular, we propose a new model that considers pulsed periodic releases, which leads to a hybrid dynamical system. This pulsed SIT model is coupled with the human population at different epidemiological states in order to assess its efficacy. Numerical simulations for the pulsed SIT, using an appropriate numerical scheme are provided. Analytical and numerical results indicate that pulsed SIT with small and frequent releases can be an alternative to chemical control tools, but only if it is used or applied early after the beginning of the epidemic or as a preventive tool. © 2011 Springer-Verlag.
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.
Weese J.S.,University of Guelph |
van Duijkeren E.,University Utrecht
Veterinary Microbiology | Year: 2010
Staphylococci are important opportunistic pathogens in most animal species. Among the most relevant species are the coagulase positive species Staphylococcus aureus and Staphylococcus pseudintermedius. Methicillin resistance has emerged as an important problem in both of these organisms, with significant concerns about animal and public health. The relative importance of these staphylococci on different animal species varies, as do the concerns about zoonotic transmission, yet it is clear that both present a challenge to veterinary medicine. © 2009 Elsevier B.V. All rights reserved.
Alkhateeb H.,Hashemite University |
Bonen A.,University of Guelph
American Journal of Physiology - Regulatory Integrative and Comparative Physiology | Year: 2010
Thujone is thought to be the main constituent of medicinal herbs that have antidiabetic properties. Therefore, we examined whether thujone ameliorated palmitate-induced insulin resistance in skeletal muscle. Soleus muscles were incubated for ≤12 h without or with palmitate (2 mM). Thujone (0.01 mg/ml), in the presence of palmitate, was provided in the last 6 h of incubation. Palmitate oxidation, AMPK/acetyl-CoA carboxylase (ACC) phosphorylation and insulin-stimulated glucose transport, plasmalemmal GLUT4, and AS160 phosphorylation were examined at 0, 6, and 12 h. Palmitate treatment for 12 h reduced fatty acid oxidation (-47%), and insulin-stimulated glucose transport (-71%), GLUT4 translocation (-40%), and AS160 phosphorylation (-26%), but it increased AMPK (+51%) and ACC phosphorylations (+44%). Thujone (6-12 h) fully rescued palmitate oxidation and insulin-stimulated glucose transport, but only partially restored GLUT4 translocation and AS160 phosphorylation, raising the possibility that an increased GLUT4 intrinsic activity may also have contributed to the restoration of glucose transport. Thujone also further increased AMPK phosphorylation but had no further effect on ACC phosphorylation. Inhibition of AMPK phosphorylation with adenine 9-β-D-arabinofuranoside (Ara) (2.5 mM) or compound C (50 μM) inhibited the thujone-induced improvement in insulin-stimulated glucose transport, GLUT4 translocation, and AS160 phosphorylation. In contrast, the thujone-induced improvement in palmitate oxidation was only slightly inhibited (≤20%) by Ara or compound C. Thus, while thujone, a medicinal herb component, rescues palmitate-induced insulin resistance in muscle, the improvement in fatty acid oxidation cannot account for this thujone-mediated effect. Instead, the rescue of palmitate-induced insulin resistance appears to occur via an AMPK-dependent mechanism involving partial restoration of insulin-stimulated GLUT4 translocation. Copyright © 2010 the American Physiological Society.
Islam T.,University of Guelph |
Meade N.,Imperial College London
Energy Policy | Year: 2013
We are concerned with micro-generation, individual households generating electricity using a renewable technology. We focus on modeling the adoption probability of photo-voltaic solar panels by households. Using data from Ontario, Canada where a generous feed-in-tariff is available to households generating electricity from solar panels, we measure household level preferences for panels and use these preferences along with household characteristics to predict adoption time intentions. We use discrete choice experiments to measure household level preferences and establish a causal link between the attributes of the technology and adoption time intentions using discrete time survival mixture analysis. Significant preferences included lower cost, greater energy savings and lower fossil fuel inflation. The conditional (hazard) probability of adoption at a particular time given no previous adoption showed that the attribute preferences had intuitively reasonable effects. The hazard probabilities allow us to compute the cumulative probability of adoption over a 10-year period per household. Technology awareness has a significant effect on the adoption probability, reinforcing the need for effective education. Our approach indicates the level of heterogeneity in preferences, particularly high for investment criteria and CO2 emissions. These findings suggest that education campaigns should explain more about investment criteria, feed-in tariffs and environmental effects. © 2012 Elsevier Ltd.
Shaffer J.F.,University of Washington |
Gillis T.E.,University of Guelph
Physiological Genomics | Year: 2010
Troponin I (TnI) and myosin binding protein-C (MyBP-C) are key regulatory proteins of contractile function in vertebrate muscle. TnI modulates the Ca 2+ activation signal, while MyBP-C regulates cross-bridge cycling kinetics. In vertebrates, each protein is distributed as tissue-specific paralogs in fast skeletal (fs), slow skeletal (ss), and cardiac (c) muscles. The purpose of this study is to characterize how TnI and MyBP-C have changed during the evolution of vertebrate striated muscle and how tissue-specific paralogs have adapted to different physiological conditions. To accomplish this we have completed phylogenetic analyses using the amino acid sequences of all known TnI and MyBP-C isoforms. This includes 99 TnI sequences (fs, ss, and c) from 51 different species and 62 MyBP-C sequences from 26 species, with representatives from each vertebrate group. Results indicate that the role of protein kinase A (PKA) and protein kinase C (PKC) in regulating contractile function has changed during the evolution of vertebrate striated muscle. This is reflected in an increased number of phosphorylatable sites in cTnI and cMyBP-C in endothermic vertebrates and the loss of two PKC sites in fsTnI in a common ancestor of mammals, birds, and reptiles. In addition, we find that His132, Val134, and Asn141 in human ssTnI, previously identified as enabling contractile function during cellular acidosis, are present in all vertebrate cTnI isoforms except those from monotremes, marsupials, and eutherian mammals. This suggests that the replacement of these residues with alternative residues coincides with the evolution of endothermy in the mammalian lineage. Copyright © 2010 the American Physiological Society.
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.
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.
Mahian O.,Islamic Azad University at Mashhad |
Mahmud S.,University of Guelph |
Zeinali Heris S.,Ferdowsi University of Mashhad
Journal of Heat Transfer | Year: 2012
In this paper, the effects of uncertainties in physical properties on predicting entropy generation for a steady laminar flow of Al 2O 3-ethylene glycol nanofluid (0 6 ) between two concentric rotating cylinders are investigated. For this purpose, six different models by combining of three relations for thermal conductivity (Bruggeman, Hamilton-Crosser, and Yu-Choi) and two relations for dynamic viscosity (Brinkman and Maiga) are applied. The governing equations with reasonable assumptions in cylindrical coordinates are simplified and solved to obtain analytical expressions for average entropy generation (N S) ave and average Bejan number (Be) ave. The results show that, when the contribution of heat transfer to entropy generation for the base fluid is dominant, a critical radius ratio (Π C) can be determined at which all six models predict the reduction in entropy generation with increases of volume fraction of nanoparticles. It is also found that, when the contribution of viscous effects to entropy generation is adequately high for the base fluid ( = 0), all models predict the increase of entropy generation with increases of particle loading. © 2012 American Society of Mechanical Engineers.
Johnson C.A.,University of Guelph |
Krishnamurthy K.,World Food Program
Global Environmental Change | Year: 2010
This article explores the possibilities of using social protection to manage and reduce the risks of forced displacement resulting from climate change. It reviews the relevant literature on migration, disasters and climate change, and constructs a model through which international policies may be used to encourage resettlement options that support the capabilities and entitlements of poor and vulnerable populations. By distinguishing between rapid-onset disasters and long-term environmental change, it explores the ways in which cash transfers, asset transfers and conditional cash transfers may be used to break the cycle of vulnerability, destitution and distress migration that can occur during times of severe environmental stress. An important distinction is made between " economic migration," which implies that households have at their disposal an opportunity to engage in forward-looking analysis about the ways in which they will invest household resources and " distress migration," which implies that household decisions about investment and migration are largely ad hoc responses to external environmental processes and events. The article reviews recent discussions about the prospects of revising the international refugee regime, and identifies the opportunities and challenges of using social protection to support household decisions that can facilitate economic migration over the long-term. © 2010 Elsevier Ltd.
Green S.R.,University of Guelph |
Schiffrin J.S.,University of Chicago |
Wald R.M.,University of Chicago
Classical and Quantum Gravity | Year: 2014
We consider perfect fluid bodies ('stars') in general relativity, with the local state of the fluid specified by its 4-velocity, ua, its 'particle number density', n, and its 'entropy per particle', s. A star is said to be in dynamic equilibrium if it is a stationary, axisymmetric solution to the Einstein-fluid equations with circular flow. A star is said to be in thermodynamic equilibrium if it is in dynamic equilibrium and its total entropy, S, is an extremum for all variations of initial data that satisfy the Einstein constraint equations and have fixed total mass, M, particle number, N, and angular momentum, J. We prove that for a star in dynamic equilibrium, the necessary and sufficient condition for thermodynamic equilibrium is constancy of angular velocity, Ω, redshifted temperature, , and redshifted chemical potential, . A star in dynamic equilibrium is said to be linearly dynamically stable if all physical, gauge invariant quantities associated with linear perturbations of the star remain bounded in time; it is said to be mode stable if there are no exponentially growing solutions that are not pure gauge. A star in thermodynamic equilibrium is said to be linearly thermodynamically stable if δ2S < 0 for all variations at fixed M, N, and J; equivalently, a star in thermodynamic equilibrium is linearly thermodynamically stable if for all variations that, to first order, satisfy δM = δN = δJ = 0 (and, hence, δS = 0). Friedman previously identified positivity of canonical energy, , as a criterion for dynamic stability and argued that all rotating stars are dynamically unstable to sufficiently non-axisymmetric perturbations (the CFS instability), so our main focus is on axisymmetric stability (although we develop our formalism and prove many results for non-axisymmetric perturbations as well). We show that for a star in dynamic equilibrium, mode stability holds with respect to all axisymmetric perturbations if is positive on a certain subspace, , of axisymmetric Lagrangian perturbations that, in particular, have vanishing Lagrangian change in angular momentum density. Conversely, if fails to be positive on , then there exist perturbations that cannot become asymptotically stationary at late times. We further show that for a star in thermodynamic equilibrium, for all Lagrangian perturbations, we have , where denotes the 'canonical energy in the rotating frame', so positivity of for perturbations with δJ = 0 is a necessary condition for thermodynamic stability. For axisymmetric perturbations, we have , so a necessary condition for thermodynamic stability with respect to axisymmetric perturbations is positivity of on all perturbations with δJ = 0, not merely on the perturbations in . Many of our results are in close parallel with the results of Hollands and Wald for the theory of black holes. © 2014 IOP Publishing Ltd.
Sneyd A.,University of Guelph
Sustainability (Switzerland) | Year: 2014
The reality that food security is a contested concept and ultimately a matter of perspective has considerable implications for Cameroon's partnerships with emerging powers. This article argues that Cameroon could achieve a more sustainable and equitable food system if greater policy attention is directed toward understanding the range of perspectives that contend to influence food security policy, and to engaging with viewpoints that vie to assess the 'footprint' of emerging powers in this area. The analysis presented below shows that the principal perspectives that compete to influence Cameroonian policy vary depending on the particular dimension of food security or aspect of emerging power activity under discussion. This finding challenges previous typologies, and encourages more nuanced interpretations of debates on these matters moving forward. © 2014 by the author.
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.
LeBlanc S.J.,University of Guelph
Animal | Year: 2014
Up to half of dairy cows are affected by at least one of metritis, purulent vaginal discharge, endometritis or cervicitis in the postpartum period. These conditions result from inadequate immune response to bacterial infection (failure to clear pathogenic bacteria from the uterus) or persistent inflammation that impairs rather than enhances reproductive function. The degree of mobilization of fat and how effectively it is used as a metabolic fuel is well recognized as a risk factor for metabolic and infectious disease. Release of non-esterified fatty acids has direct effects on liver and immune function but also produces pro-inflammatory cytokines (tumor necrosis factor α and interleukin-6), which contribute to systemic inflammation and to insulin resistance. Therefore, reproductive tract inflammatory disease may be a function of both local and systemic inflammatory stimuli and regulation as well as regulation of fat metabolism. Better understanding of variables associated with insulin resistance and inflammatory regulation in the liver and adipose tissue may lead to improvement of reproductive tract health. This paper reviews factors that may contribute to postpartum reproductive tract inflammatory diseases in dairy cows and their inter-relationships, impacts and treatment. © 2014 The Animal Consortium.
Gabler M.,University of Guelph
Global Environmental Politics | Year: 2010
The United Nations Conference on Environment and Development (UNCED) recognized that sustainable development can only be actualized if environmental norms are integrated into other areas of policy across levels of governance. This article examines the Committee on Trade and Environment of the World Trade Organization (WTO) to answer the question of why actors' efforts to enhance the mutual supportiveness of trade and environmental norms have resulted in minimalist policy outcomes. I first introduce a framework for analyzing norms and their levels of compatibility and a social learning explanation for policy integration emphasizing the importance of normative and institutional conditions. Second, I show that low levels of both norm compatibility between UNCED and WTO and institutional capacity in the WTO for learning have contributed to weak integration. The approach contributes to constructivist theory development and the findings provide insights to policy-makers grappling with how to support the integration of norms and institutions in global governance. © 2010 by the Massachusetts Institute of Technology.
Wilson J.J.,University of Guelph
PLoS ONE | Year: 2011
Background: A common perception is that DNA barcode datamatrices have limited phylogenetic signal due to the small number of characters available per taxon. However, another school of thought suggests that the massively increased taxon sampling afforded through the use of DNA barcodes may considerably increase the phylogenetic signal present in a datamatrix. Here I test this hypothesis using a large dataset of macrolepidopteran DNA barcodes. Methodology/Principal Findings: Taxon sampling was systematically increased in datamatrices containing macrolepidopteran DNA barcodes. Sixteen family groups were designated as concordance groups and two quantitative measures; the taxon consistency index and the taxon retention index, were used to assess any changes in phylogenetic signal as a result of the increase in taxon sampling. DNA barcodes alone, even with maximal taxon sampling (500 species per family), were not sufficient to reconstruct monophyly of families and increased taxon sampling generally increased the number of clades formed per family. However, the scores indicated a similar level of taxon retention (species from a family clustering together) in the cladograms as the number of species included in the datamatrix was increased, suggesting substantial phylogenetic signal below the 'family' branch. Conclusions/Significance: The development of supermatrix, supertree or constrained tree approaches could enable the exploitation of the massive taxon sampling afforded through DNA barcodes for phylogenetics, connecting the twigs resolved by barcodes to the deep branches resolved through phylogenomics. © 2011 John James Wilson.
Schattat M.H.,University of Guelph
The Plant cell | Year: 2012
Stroma-filled tubules named stromules are sporadic extensions of plastids. Earlier, photobleaching was used to demonstrate fluorescent protein diffusion between already interconnected plastids and formed the basis for suggesting that all plastids are able to form networks for exchanging macromolecules. However, a critical appraisal of literature shows that this conjecture is not supported by unequivocal experimental evidence. Here, using photoconvertible mEosFP, we created color differences between similar organelles that enabled us to distinguish clearly between organelle fusion and nonfusion events. Individual plastids, despite conveying a strong impression of interactivity and fusion, maintained well-defined boundaries and did not exchange fluorescent proteins. Moreover, the high pleomorphy of etioplasts from dark-grown seedlings, leucoplasts from roots, and assorted plastids in the accumulation and replication of chloroplasts5 (arc5), arc6, and phosphoglucomutase1 mutants of Arabidopsis thaliana suggested that a single plastid unit might be easily mistaken for interconnected plastids. Our observations provide succinct evidence to refute the long-standing dogma of interplastid connectivity. The ability to create and maintain a large number of unique biochemical factories in the form of singular plastids might be a key feature underlying the versatility of green plants as it provides increased internal diversity for them to combat a wide range of environmental fluctuations and stresses.
Mark K.P.,Indiana University |
Murray S.H.,University of Guelph
Journal of Sex and Marital Therapy | Year: 2012
The authors examined desire discrepancy and its effect on sexual and relationship satisfaction in a sample of 133 heterosexual couples attending a midsize university. Couples were required to be in a relationship for at least 1 year (M = 4.32 years, SD = 3.13 years); 23.7% of the couples were cohabitating. Hierarchical multiple regression results indicated that higher desire discrepancy scores significantly predicted women's (but not men's) lower sexual satisfaction after controlling for relationship satisfaction. Higher desire discrepancy scores significantly predicted men's (but not women's) lower relationship satisfaction after controlling for sexual satisfaction. The authors assessed gender differences using a mixed model with the dyad and gender as factors and satisfaction as the outcome. Although gender difference patterns appeared in the regression models, the differences were nonsignificant within each couple in the extent to which desire discrepancy affected sexual and relationship satisfaction. These findings suggest moving away from focusing on only one partner with low desire and shifting attention to the dyad's interaction. Also, the way in which desire discrepancy affects sexual and relationship satisfaction deserves consideration. Therapeutic implications and study limitations are discussed. © 2012 Copyright Taylor and Francis Group, LLC.
Pant L.P.,University of Guelph
Technological Forecasting and Social Change | Year: 2016
Paradox of mainstreaming agroecology refers to an apparent contradiction between upscaling niche innovations to produce more food in sustainable ways, and the concerns for a loss of core values and principles of agroecology in the mainstreaming process. This paper examines this paradox of mainstreaming and sidestreaming (continuity of niche practises) using longitudinal case studies of agroecological innovations in soil and water conservation, crop improvement, crop intensification, and market differentiation in the regional and rural contexts of developing countries. Findings suggest that there are latent and salient paradoxes of mainstreaming niche innovations, respectively explaining cooperative and competitive interactions with the incumbent regime of industrial food and agriculture. While the former paradox involves continuity of niche practises as well as regime conditions through incremental adaptations, the latter comprises regime shifts through transformational adaptations. However, as these two paradoxes are in flux a latent paradox can become salient when competitive elements of seemingly cooperative niche-regime interactions unravel. © 2016 Elsevier Inc.
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.
Kukkonen T.M.,University of Guelph
Current Sexual Health Reports | Year: 2014
A number of instruments have been developed for the physiological measurement of female sexual response. While vaginal photoplethysmography (VPP) remains the most widely used instrument to date, a number of alternate technologies have been examined to address the limitations in the literature on female sexual arousal. In the past 10 years, VPP, ultrasonography, temperature measurement via thermistors and thermographic cameras, magnetic resonance imaging, laser Doppler imaging, and labial and clitoral photoplethysmography have all been used to assess sexual response. To establish which method is best, one must consider the output of each device; how the data generated relate to self-reported sexual arousal; quantitative strengths and limitations and practical issues that arise in using each instrument. Based on these criteria, it appears that ultrasonography is well suited for analysis of genital structures, while temperature measurement provides the strongest evidence for use in research as a methodology for assessing female sexual response. © 2014 Springer Science+Business Media, LLC.
Thomas V.G.,University of Guelph
Environmentalist | Year: 2010
Lead from spent ammunition causes preventable lead exposure in wildlife and humans that may ingest it. Nontoxic substitutes for lead ammunition exist but are not adopted widely because of hunter opposition. Other forms of lead exposure in the human environment have been heavily regulated because there is no safe level of exposure. The use of lead ammunition should be regulated similarly to protect wildlife from this common disease. © Springer Science+Business Media, LLC 2010.
Mishra S.,University of Regina |
Barclay P.,University of Guelph |
Lalumiere M.L.,University of Ottawa
Evolution and Human Behavior | Year: 2014
Risk-sensitivity theory predicts that organisms are more likely to take risks when they are unlikely to achieve their goals through safer, low-risk means. Those who are competitively disadvantaged are less likely to succeed in social competition and should consequently show elevated risk taking. We experimentally tested this hypothesis by exposing participants to cues of relative competitive disadvantage or relative competitive advantage via feedback from a purported reaction time based intelligence test. Participants then made a number of high-risk or low-risk economic decisions (Experiment 1). Experiment 2 built on this design by either maintaining or ameliorating cues of relative competitive (dis)advantage. Results indicate that cues of relative competitive disadvantage leads to increased risk taking, and that risk taking can be reduced when cues of disadvantage are ameliorated. Since risk taking tends to generalize across domains, these results can potentially apply to a number of problematic risky behaviors. © 2014 Elsevier Inc.
Gill R.J.,Royal Holloway, University of London |
Gill R.J.,Imperial College London |
Raine N.E.,Royal Holloway, University of London |
Raine N.E.,University of Guelph
Functional Ecology | Year: 2014
Insect pollination is a vital ecosystem service that maintains biodiversity and sustains agricultural crop yields. Social bees are essential insect pollinators, so it is concerning that their populations are in global decline. Although pesticide exposure has been implicated as a possible cause for bee declines, we currently have a limited understanding of the risk these chemicals pose. Whilst environmental exposure to pesticides typically has non-lethal effects on individual bees, recent reports suggest that sublethal exposure can affect important behavioural traits such as foraging. However, at present, we know comparatively little about how natural foraging behaviour is impaired and the relative impacts of acute and chronic effects. Using Radio-Frequency Identification (RFID) tagging technology, we examined how the day-to-day foraging patterns of bumblebees (Bombus terrestris) were affected when exposed to either a neonicotinoid (imidacloprid) and/or a pyrethroid (λ-cyhalothrin) independently and in combination over a four-week period. This is the first study to provide data on the impacts of combined and individual pesticide exposure on the temporal dynamics of foraging behaviour in the field over a prolonged period of time. Our results show that neonicotinoid exposure has both acute and chronic effects on overall foraging activity. Whilst foragers from control colonies improved their pollen foraging performance as they gained experience, the performance of bees exposed to imidacloprid became worse: chronic behavioural impairment. We also found evidence, suggesting that pesticide exposure can change forager preferences for the flower types from which they collect pollen. Our findings highlight the importance of considering prolonged exposure (which happens in the field) when assessing the risk that pesticides pose to bees. The effects of chronic pesticide exposure could have serious detrimental consequences for both colony survival and also the pollination services provided by these essential insect pollinators. © 2014 British Ecological Society.
Cutler G.C.,Dalhousie University |
Scott-Dupree C.D.,University of Guelph |
Drexler D.M.,Consulting Inc.
Pest Management Science | Year: 2014
BACKGROUND: Neonicotinoid insecticides have been the target of much scrutiny as possible causes of recent declines observed in pollinator populations. Although neonicotinoids have been implicated in honey bee pesticide incidents, there has been little examination of incident report data. Here we summarize honey bee incident report data obtained from the Canadian Pest Management Regulatory Agency (PMRA). RESULTS: In Canada, there were very few honey bee incidents reported in 2007-2011 and data were not collected prior to 2007. In 2012, a significant number of incidents were reported in the province of Ontario, where exposure to neonicotinoid dust during planting of corn was suspected to have caused the incident in up to 70% of cases. Most of these incidents were classified as 'minor' by the PMRA, and only six cases were considered 'moderate' or 'major'. In that same year, there were over three times as many moderate or major incidents due to older non-neonicotinoid pesticides, involving numbers of hives or bees far greater than the number of moderate or major incidents suspected to be due to neonicotinoid poisoning. CONCLUSIONS: These data emphasize that, while exposure of honey bees to neonicotinoid-contaminated dust during corn planting needs to be mitigated, other pesticides also pose a risk. © 2013 Society of Chemical Industry.
LeBlanc C.,University of Guelph
Cattle Practice | Year: 2014
The foundations of fertility in dairy cows are laid in the transition period. Excessive negative energy balance is an important risk factor for reproductive tract disease and impairment or delay of return to a fertile oestrus cycle. Diminished immune response is an important risk factor for metritis and endometritis, and it is increasingly recognised that excessive inflammation is an important element of both metabolic and reproductive disease that links current concepts of health the peripartum period. While specific preventive and therapeutic interventions are elusive, best management practices for housing and nutrition are likely to support metabolic health, immune function, and in turn, reproductive performance.
Bailey H.N.,University of Guelph
Emotion (Washington, D.C.) | Year: 2012
Attachment anxiety has been associated with a hyperactivating response to threat. A modified emotional Stroop task was used to investigate temporal characteristics of the threat response by assessing response latencies to interpersonally threatening words (immediate interference) and two directly subsequent neutral filler words (delayed interference). Greater immediate and delayed interference to threatening words was observed (n = 125), with higher levels of attachment anxiety associated with immediate interference to threatening cues, and lower levels with delayed interference. Thus, attachment anxiety was related to the speed at which moderate perceived threat disrupted ongoing processes under top-down attentional control. Furthermore, top-down attentional control moderated the extent to which immediate or delayed interference was observed. Among participants who demonstrated relatively stronger top-down attentional control, immediate and delayed interference to threatening cues was minimal, suggesting that results involving emotional Stroop interference were primarily attributable to participants with relatively weaker top-down attentional control. The implications of these findings are considered within the broader context of performance-based and neuroimaging research, with suggestions for future applied research. (PsycINFO Database Record (c) 2012 APA, all rights reserved).
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.
Arnaud E.,University of Guelph
Sedimentary Geology | Year: 2012
This paper reviews the different types of soft sediment deformation structures that can form in glacial and non-glacial settings and explores the potential use of these structures in resolving long standing debates in paleoenvironmental reconstructions of Neoproterozoic glacigenic successions. Soft sediment deformation structures are created when compressional, gravitational or shear stress is applied to unlithified sediments during or shortly after deposition. In subglacial or ice marginal glacial settings, shear and compressional stress imparted by ice moving on top of a deformable substrate or advancing ice buldozing unlithified ice marginal sediments can result in a wide range of folding, faulting and shear structures. In glaciofluvial or stagnant ice marginal setting, gravitational collapse and remobilization of sediments associated with the melting of buried ice can result in normal faulting and broad folding. In glaciolacustrine or glaciomarine settings, compressional, shear and gravitational types of deformation structures can occur as a result of grounding ice or icebergs, rapid sedimentation and reworking downslope associated with high sedimentation rates. In non glacial settings, similar deformation structures can form as a result of slope instability and reworking of sediments downslope, rapid sedimentation, seismic shaking, wave induced shearing or loading. In this context, two case studies are presented to demonstrate the type of paleoenvironmental information that an analysis of deformation structures can provide. In the first case study, analysis of deformation in the Port Askaig Formation (Scotland) reveals a distinctive stratigraphic distribution of deformation structures. The types of deformation observed together with their recurrence over several 100s of meters and their basinal context are used to infer a seismic origin for the deformation, which in turn suggests a significant tectonic control on sedimentation atop a record of ice margin fluctuations in a glaciomarine setting. In the second example, analysis of deformation in the Smalfjord Formation (northern Norway) provides strong evidence for deformation by active ice overriding glaciofluvial deposits. The types of deformation in this example, together with its complexity, scale and associated facies, provide the strongest case for ice marginal deformation. In sum, analysis of deformation structures together with analysis of structural geology, stratigraphy, facies and facies associations can provide additional constraints on paleoenvironmental conditions at the time of deposition, which can help us refine or test paleoenvironmental models proposed for this critical time period in Earth history. © 2011 Elsevier B.V.
Zimmerman P.,University of Guelph
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015
Motivated by the theoretical possibility of floating orbits and the potential to contribute extra constraints on alternative theories, in this paper we derive the self-force equation for a small compact object moving on an accelerated world line in a background spacetime which is a solution of the coupled gravitational and scalar field equations of scalar-tensor theory. In the Einstein frame, the coupled field equations governing the perturbations sourced by the particle share the same form as the field equations for perturbations of a scalarvac spacetime in general relativity, with both falling under the general class of hyperbolic field equations studied in . Here, we solve the field equations formally in terms of retarded Green functions, which have explicit representations as Hadamard forms in the neighborhood of the world line. Using a quasilocal expansion of the Hadamard form, we derive the regular solutions in Fermi normal coordinates according to the Detweiler-Whiting prescription. To compute the equation of motion, we parametrize the world line by the particle's mass and "charge," which we define in terms of the original Jordan frame mass, its derivative, and the parameter which translates the proper time in the Jordan frame to the Einstein frame. These parameters depend on the value of the background scalar field and its self-field corrections. The equation of motion which follows from the regular fields strongly resembles the equation for the self-force acting on a charged, massive particle in a scalarvac geometry of general relativity. Unlike the scalar vacuum scenario, the charge parameter in the scalar-tensor self-force equation is time variable and leading to additional local and tail terms. We also provide evolution equations for the world line parameters under the influence of the self-fields. © 2015 American Physical Society.
Bag J.,University of Guelph
RNA biology | Year: 2010
Regulation of gene expression at the post-transcriptional level such as control of mRNA translation and stability is of fundamental importance because it allows cells to respond quickly to external signals, and change protein synthesis without new transcriptional activity. As such, control of translation and stability of mRNA play crucial roles in a variety of cellular processes, including regulating normal cellular growth, embryogenesis and neuronal plasticity. Consequently, misregulation of mRNA translation or degradation can be associated with a number of human diseases, such as cancer and diabetes. Studies have shown that the cytoplasmic poly (A)-binding protein (PABP) plays a crucial role in regulating both translation and stability of eukaryotic mRNA.
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.
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.
Perkins N.H.,University of Guelph
Facilities | Year: 2013
Purpose: Participation by patients, staff and visitors in healthcare design and planning offers multiple benefits in addressing the complex challenges of creating salutary environments for hospital patients, staff and visitors. The purpose of this paper is to present the benefits of participatory design and design imperatives to facilities architects and landscape architects. Design/methodology/approach: The paper describes three case studies in which participatory methods were used to engage users in decision making over 15 years and creates a framework using "design imperatives" that has been successful in the design of outdoor settings. Findings: Nine design imperatives can be used to design facilities that achieve a range of therapeutic benefits for patients, staff and visitors. Research limitations/implications: The research limitations of this paper are those of using case studies in general. The implications suggest that papers such as this can be used in future hypothesis-driven research. Practical implications: Designers do not have the luxury or ability to base myriad design decisions on experimental research findings, as almost all design is unique and a hypothesis waiting to be tested. The result is that guiding principles, or design imperatives based on participatory methods, can form the basis for design decision making. Social implications: The social implications are that some form of participatory decision making in facilities design has benefits to multiple constituencies, specifically, patients, staff and visitors. Originality/value: Although this paper refers to many existing studies and places the results and conclusions within a context that is supported by the literature, much of the value is because the results are based on practice. More than a dozen projects form the basis for concluding that general principles of design, person-environment interactions and participatory methods lead to desirable and beneficial outcomes. © Emerald Group Publishing Limited.
Spriet L.L.,University of Guelph
Sports Medicine | Year: 2014
Caffeine is a popular work-enhancing supplement that has been actively researched since the 1970s. The majority of research has examined the effects of moderate to high caffeine doses (5–13 mg/kg body mass) on exercise and sport. These caffeine doses have profound effects on the responses to exercise at the whole-body level and are associated with variable results and some undesirable side effects. Low doses of caffeine (<3 mg/kg body mass, ~200 mg) are also ergogenic in some exercise and sport situations, although this has been less well studied. Lower caffeine doses (1) do not alter the peripheral whole-body responses to exercise; (2) improve vigilance, alertness, and mood and cognitive processes during and after exercise; and (3) are associated with few, if any, side effects. Therefore, the ergogenic effect of low caffeine doses appears to result from alterations in the central nervous system. However, several aspects of consuming low doses of caffeine remain unresolved and suffer from a paucity of research, including the potential effects on high-intensity sprint and burst activities. The responses to low doses of caffeine are also variable and athletes need to determine whether the ingestion of ~200 mg of caffeine before and/or during training and competitions is ergogenic on an individual basis. © 2014, The Author(s).
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.
Caruso C.M.,University of Guelph |
Case A.L.,Kent State University |
Bailey M.F.,Providence College
Trends in Plant Science | Year: 2012
Interactions between cytoplasmic and nuclear genomes have significant evolutionary consequences. In angiosperms, the most common cytonuclear interaction is between mitochondrial genes that disrupt pollen production (cytoplasmic male sterility, CMS) and nuclear genes that restore it (nuclear male fertility restorers, Rf). The outcome of CMS/. Rf interactions can depend on whether Rf alleles have negative pleiotropic effects on fitness. Although these fitness costs are often considered to be independent of the ecological context, we argue that the effects of Rf alleles on fitness should be context dependent. Thus, measuring the cost of restoration across a range of environments could help explain geographic and phylogenetic variation in the distribution of Rf alleles and the outcome of CMS/. Rf interactions. © 2012 Elsevier Ltd.
Carr C.M.,University of Guelph
Marine Biodiversity | Year: 2012
As changes to Canada's marine biodiversity loom and the tools for assessing biodiversity advance, it becomes increasingly important to have baseline information about a region's species so that future comparisons can be made. The polychaetes represent a conspicuous component of benthic communities in Canadian marine waters, yet information on species diversity and distribution is available only at the local scale. This study compiles polychaete species records from Canada over the last 150 years to assess broad-scale patterns of species richness, beta diversity (partitioned into turnover and nestedness), and species distributions in the surrounding Atlantic, Arctic, and Pacific Oceans. Records indicate the presence of 1200 species belonging to 68 families, while statistical extrapolation estimated a total of 1629 species. Pacific waters have the highest richness with 791 recorded species. The eastern and western regions of the Arctic Ocean have the highest faunal similarity, but the fewest endemic species, reflecting the recent ice-free status of this basin. Species turnover is highest between Pacific and Atlantic basins, decreases with geographic proximity, and is lowest in comparisons with Hudson Bay. Similar patterns of turnover between temperate and (sub)Arctic basins suggest that both Atlantic and Pacific faunas played an important role in Arctic recolonization following deglaciation. Despite the vast geographic area, nearly 13% of species are reported in all three oceans; however, many of these taxa likely represent species complexes. These results highlight the need for more detailed examination of many species with broad distributions and suggest that diversity in Canada is currently underestimated. © 2011 Senckenberg, Gesellschaft für Naturforschung and Springer.
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.
Marangoni A.G.,University of Guelph
JAOCS, Journal of the American Oil Chemists' Society | Year: 2012
Structuring liquid oils has become an active area of research in the past decade, mainly due to pressures to reduce saturated fat intake and eliminate trans fats from our diets. However, replacing hard fats with liquid oil can lead to major changes in the quality of food products. Recent strategies to impart solid-fat functionality to liquid oils include the addition of unusual compounds to oil, leading to its gelation. These include small-molecule organogelators such as phytosterols and 12-hydroxystearic acid, which self-assemble into crystalline fibers which trap oil. Other crystalline additives include waxes, ceramides, monoacylglycerides, and other surfactants. Recently, the polymer ethyl cellulose was reported to form a polymer gel in triacylglyceride (TAG) oils. Other non-conventional strategies also include the formation of protein-stabilized cellular solids with oil trapped within the cells. In this review, we summarize the research on each one of these components in order to provide a comprehensive overview of the state of the area in oleogel research and provide future perspectives. © AOCS 2012.
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.
McEwen B.J.,University of Guelph
Journal of Forensic Sciences | Year: 2012
Pathologists at veterinary diagnostic laboratories receive medico-legal cases from a variety of animal species for postmortem examination. A search of computerized records of the Animal Health Laboratory, University of Guelph, Guelph, Ontario, Canada from 1998 to 2010 identified 1706 medicolegal cases. These were categorized according to the history as criminal investigations, anesthetic-related deaths, insurance, litigation, malpractice cases, and regulatory cases. Statistically significant linear trends in the proportion of medicolegal cases for all animals and criminal cases for companion animals were identified over the 12year period. Companion animals had significantly greater odds of being a medicolegal case in all categories except for insurance and regulatory cases, compared to noncompanion animals. Based on pathology reports for the 271 criminal cases, 43.1% were consistent with neglect, 29.2% were compatible with non-accidental injury, 4.80% were poisonings, 10.7% were deemed to be due to natural disease, and 11.43% were inconclusive. © 2012 American Academy of Forensic Sciences.
Boston S.,University of Florida |
Singh A.,University of Guelph
Veterinary Surgery | Year: 2014
Objective: To report total cystectomy with reimplantation of the ureters in the proximal aspect of the vagina. Study Design: Case report. Animals: An 11-year-old female spayed Vizsla with spontaneously occurring transitional cell carcinoma of the urethra and bladder. Methods: After initial treatment for transitional cell carcinoma of the bladder trigone with urethral stent placement and chemotherapy, the dog developed urinary incontinence 2 months after stent placement. Eleven months after initial diagnosis, the dog developed pulmonary metastasis and local progression, leading to bilateral ureteral dilatation. After palliative radiation, total cystectomy was performed. Results: The owners elected euthanasia 442 days after original presentation and 92 days after total cystectomy. Euthanasia was unrelated to the surgical procedure, but was related to the primary disease. Conclusions: Total cystectomy is a technically feasible procedure that should be considered for the treatment of bladder cancer in dogs. © 2014 by The American College of Veterinary Surgeons.
Strommer J.,University of Guelph
Plant Journal | Year: 2011
The structures, evolution and functions of alcohol dehydrogenase gene families and their products have been scrutinized for half a century. Our understanding of the enzyme structure and catalytic activity of plant alcohol dehydrogenase (ADH-P) is based on the vast amount of information available for its animal counterpart. The probable origins of the enzyme from a simple β-coil and eventual emergence from a glutathione-dependent formaldehyde dehydrogenase have been well described. There is compelling evidence that the small ADH gene families found in plants today are the survivors of multiple rounds of gene expansion and contraction. To the probable original function of their products in the terminal reaction of anaerobic fermentation have been added roles in yeast-like aerobic fermentation and the production of characteristic scents that act to attract animals that serve as pollinators or agents of seed dispersal and to protect against herbivores. © 2011 The Author.
Zimmerman P.,University of Guelph
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015
In this paper we investigate the motion of small compact objects in nonvacuum spacetimes using methods from effective field theory in curved spacetime. Although a vacuum formulation is sufficient in many astrophysical contexts, there are applications such as the role of the self-force in enforcing cosmic censorship in the context of the overcharging problem, which necessitate an extension into the nonvacuum regime. The defining feature of the self-force problem in nonvacuum spacetimes is the coupling between gravitational and nongravitational field perturbations. The formulation of the self-force problem for nonvacuum spacetimes was recently provided in simultaneous papers by Zimmerman and Poisson [Gravitational self-force in nonvacuum spacetimes, Phys. Rev. D 90, 084030 (2014)] and Linz, Friedmann, and Wiseman [Combined gravitational and electromagnetic self-force on charged particles in electrovac spacetimes, Phys. Rev. D 90, 084031 (2014)]. Here we distinguish ourselves by working with the effective action rather than the field equations. The formalism utilizes the multi-index notation developed by Zimmerman and Poisson [Gravitational self-force in nonvacuum spacetimes, Phys. Rev. D 90, 084030 (2014) to accommodate the coupling between the different fields. Using dimensional regularization, we arrive at a finite expression for the local self-force expressed in terms of multi-index quantities evaluated in the background spacetime. We then apply the formalism to compute the coupled gravitational self-force in two explicit cases. First, we calculate the self-force on a massive particle possessing scalar charge and moving in a scalarvac spacetime. We then derive an expression for the self-force on an electrically charged, massive particle moving in an electrovac spacetime. In both cases, the force is expressed as a sum of local terms involving tensors defined in the background spacetime and evaluated at the current position of the particle, as well as tail integrals that depend on the past history of the particle. © 2015 American Physical Society.
Opperman E.A.,University of Guelph
Spinal Cord | Year: 2010
Study design:Literature review. Objectives:Urinary tract infections (UTIs) are the most common medical complication experienced by individuals with spinal cord injury (SCI). Recent research presents conflicting evidence regarding use of cranberry in reducing growth and colonization of uroepithelial cells by uropathogenic bacteria. The objective was to determine whether the literature supports the use of cranberry in preventing or treating UTIs in the SCI population. Methods:MEDLINE was searched for intervention studies, which investigated the use of cranberry in the prevention or treatment of UTIs in the SCI population. If the studies met the inclusion criteria, full articles were located and reviewed. Results:Five studies (four randomized clinical controlthree trials using cranberry tablets vs placebos and one using cranberry juiceand one pilot study using cranberry juice) were identified which evaluated the effectiveness of cranberry products for the prevention or treatment of UTIs in the SCI population. Three studies reported no statistically significant effect of cranberry tablets in urinary pH, urinary bacterial count, urinary white blood cell (WBC) count, urinary bacterial, and WBC counts in combination or episodes of symptomatic UTIs. A fourth study showed that cranberry juice intake significantly reduced biofilm load compared with baseline. A final study reported fewer UTIs during the period with cranberry extract tablets vs placebo. Conclusions:Limited evidence from clinical trials that vary in design suggests that cranberry, in juice or supplement form, does not seem to be effective in preventing or treating UTIs in the SCI population. More rigorous clinical research is needed to confirm this. © 2010 International Spinal Cord Society All rights reserved.
Mendes R.F.P.,University of Guelph
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015
Scalar-tensor theories (STTs) are a widely studied alternative to general relativity (GR) in which gravity is endowed with an additional scalar degree of freedom. Although severely constrained by solar system and pulsar timing experiments, there remains a large set of STTs which are consistent with all present day observations. In this paper, we investigate the possibility of probing a yet unconstrained region of the parameter space of STTs based on the fact that stability properties of highly compact neutron stars in these theories may radically differ from those in GR. © 2015 American Physical Society.
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.
Lindinger M.I.,University of Guelph |
Heigenhauser G.J.F.,McMaster University
Comprehensive Physiology | Year: 2012
This paper describes the interactions between ventilation and acid-base balance under a variety of conditions including rest, exercise, altitude, pregnancy, and various muscle, respiratory, cardiac, and renal pathologies. We introduce the physicochemical approach to assessing acid-base status and demonstrate how this approach can be used to quantify the origins of acid-base disorders using examples from the literature. The relationships between chemoreceptor and metaboreceptor control of ventilation and acid-base balance summarized here for adults, youth, and in various pathological conditions. There is a dynamic interplay between disturbances in acid-base balance, that is, exercise, that affect ventilation as well as imposed or pathological disturbances of ventilation that affect acid-base balance. Interactions between ventilation and acid-base balance are highlighted for moderate- to high-intensity exercise, altitude, induced acidosis and alkalosis, pregnancy, obesity, and some pathological conditions. In many situations, complete acid-base data are lacking, indicating a need for further research aimed at elucidating mechanistic bases for relationships between alterations in acid-base state and the ventilatory responses. © 2012 American Physiological Society.
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.
Chang S.,University of Guelph
Desalination | Year: 2011
The main objective of this paper is to provide a review on the engineering concept of the submerged hollowfiber module and its operation in MBRs. The main design characteristics of the submerged hollow-fiber membrane modules, the filtration behavior of hollow fibers, the MBR system composition, the main design and operation parameters, and the membrane fouling under the subcritical flux condition in MBRs have been discussed in this paper. It is expected that this paper can provide improved understanding on the key design parameters of the submerged hollow fiber membrane modules, the non-uniform filtration behavior of the hollow fibers, the difference between the actual and observed fiber membrane permeability, the typical MBR system design and operation parameters, the filtration cycle TMP behavior, the operation strategies for the peak flow conditions, and the mechanisms of the development of the long-termmembrane fouling under subcritical flux conditions. © 2011 Elsevier B.V.
LeBlanc S.J.,University of Guelph |
Osawa T.,Iwate University |
Dubuc J.,University of Montreal
Theriogenology | Year: 2011
This paper briefly reviews recent data and concepts on the development and mitigation of infection and inflammation in the reproductive tract of dairy cows during the first 2 mo after calving. The incidence of metritis is typically between 10 and 20%, of clinical endometritis or purulent vaginal discharge (PVD) approximately 15%, and of subclinical or cytological endometritis a further 15%. Worse postpartum negative energy balance is associated with more severe or prolonged uterine inflammation. Changes in feed intake, expression of genes for pro-inflammatory cytokines, notably interleukin (IL) 1, IL6 and IL8, circulating concentrations of beta-hydroxybutyrate (BHBA) or nonesterified fatty acids (NEFA), and innate immune function precede both metritis and endometritis by several weeks. Infections with Escherichia coli and Arcanobacterium pyogenes are associated with both metritis and PVD. There are new data to suggest that specific virulence factors in E. coli associated with adherence may be important in metritis and PVD. Cytological endometritis and PVD are overlapping but largely distinct conditions, and there are emerging data that cervicitis exists both concurrent with and separate from endometritis. Much remains to be learned about what initiates and sustains harmful inflammation of the reproductive tract. Such information is necessary to develop effective treatments for the various forms of disease and, more importantly, to develop means to prevent endometritis and cervicitis. In particular, vaccination against specific uterine pathogens and interventions to modulate innate immune response appear to be important avenues for investigation. Presently, commonly recommended best management practices for cows in the transition period are likely to be helpful to mitigate the risk of reproductive disease. © 2011 Elsevier Inc.
Vyn R.J.,University of Guelph |
Mccullough R.M.,Policy Analyst
Canadian Journal of Agricultural Economics | Year: 2014
The increasing development of wind energy in North America has generated concerns from nearby residents regarding potential impacts of wind turbines on property values. Such concerns arose in Melancthon Township (in southern Ontario) following the construction of a large wind farm. Existing literature has not reached a consensus regarding the nature of these impacts. This paper applies a hedonic approach to detailed data on 5,414 rural residential sales and 1,590 farmland sales to estimate the impacts of Melancthon's wind turbines on surrounding property values. These impacts are accounted for through both proximity to turbines and turbine visibility-two factors that may contribute to a disamenity effect. The results of the hedonic models, which are robust to a number of alternate model specifications including a repeat sales analysis, suggest that these wind turbines have not significantly impacted nearby property values. Thus, these results do not corroborate the concerns raised by residents regarding potential negative impacts of turbines on property values. © 2014 Canadian Agricultural Economics Society.
Thomas V.G.,University of Guelph
European Journal of Wildlife Research | Year: 2016
Failure to distinguish between elemental tungsten and tungsten alloys has caused confusion, especially about their relative toxicity in shotgun ammunition. Controlled experiments indicate that the carcinogenicity of embedded tungsten–nickel–cobalt alloys derives from their nickel and cobalt content, and not the tungsten. The carcinogenicity of metallic nickel and cobalt implants in animal tissues is well-established. Studies in which pure tungsten metal is embedded in animal and human tissues indicate that there is no toxicity or carcinogenicity developed locally or systemically. The exposed tungsten corrodes slowly in the tissue fluids and is excreted from the body. Chronic studies in which pure tungsten-based shot are placed, continuously, in the foregut of ducks over 150 days indicate that there are no adverse physiological effects, nor disruption of ducks’ reproduction and development of their progeny. This type of shot is environmentally safe and non-toxic to animals. Shot containing nickel could pose health problems to animals if embedded in their tissues. The use of known toxic metals in lead-free shot should be subjected to further examination and, if warranted, regulation. © 2015, Springer-Verlag Berlin Heidelberg.
Canbolat M.S.,New York University |
Von Massow M.,University of Guelph
Expert Systems with Applications | Year: 2011
Locating emergency service facilities is a challenging problem. Planners do not know specifically where emergencies will occur and, therefore, struggle to find a location that effectively ensures that the risk of poor service to any specific emergency is minimized. In this paper, we study the problem where locations of each demand point (emergency occurence) are random. Our objective is to minimize the expected maximum rectilinear distance from the facility to the demand points. This problem has practical importance in public sector as it aims to minimize the expected maximum risk when locating an emergency response facility. We start with a one dimensional problem and extend the results to the more complex two dimensional case. We present some properties of the problem along with examples for special cases. We propose a simulation approach to solving complex two dimensional cases and present simulation results for general cases to illustrate the problem and provide insight into solutions. We show that the simulation approach provides solutions very close to optimal for the linear case and suggest that it may provide valuable insight into the location selection system. © 2011 Published by Elsevier Ltd.
Di Stefano B.N.,Nuptek Systems Ltd. |
Lawniczak A.T.,University of Guelph
Acta Physica Polonica B, Proceedings Supplement | Year: 2012
Agent-based models approximate the behaviour of simple natural and man-made systems. Their performance is limited by the abstractions used to implement them, i.e., finite state machines. "Cognitive Agents" perform "Cognitive Acts" (i.e., Perceiving, Reasoning, Judging, Responding, and Learning) and are the closest to the behaviour of simple biological entities. We present a simple cognitive agent capable of evaluating if a strategy has been applied successfully and capable of applying this strategy again with small changes to a similar but new situation. We describe how a simple agent can be trained to learn how to safely cross a road with "one lane one directional highway" and later, when the situation changes, a road with "two lanes one directional highway" and "two lanes on a bi-directional highway". Future research is outlined.
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.
Atalla H.,University of Guelph
Animal health research reviews / Conference of Research Workers in Animal Diseases | Year: 2011
Persistent or difficult-to-treat Staphylococcus aureus infections in animals and humans may be related to small colony variants (SCVs) that can hide inside host cells and modulate host defenses. S. aureus SCVs have gained much attention in human medicine but have been underestimated and overlooked in veterinary medicine. Recently, an SCV isolated from a dairy cow with a history of chronic mastitis was shown to possess similar phenotypic and transcriptomic properties to those of human SCVs. SCVs form small, colorless, non-hemolytic colonies after 48 h, are only slowly coagulase positive, fail to ferment mannitol, and can revert to the parental phenotype. The phenotype of SCVs is mostly related to alterations in hemin and/or menadione biosynthesis or to thymidine deficiency. Transcriptomic analysis of SCVs shows up-regulation of genes involved in glycolytic and arginine-deiminase pathways, capsular biosynthesis; increased sigma B activity; and down-regulation of genes for α-hemolysin, coagulase and effector molecule RNA III of the global virulence regulator Agr. Similar results are reported at the protein level. SCVs are less virulent but successful persisters in infection models. SCVs persist longer and at higher numbers within non-phagocytes than do their parents. SCVs survive within spacious vacuoles up to 24 h within cultured bovine mammary epithelial cells, likely due to up-regulation of protective mechanisms that counteract the lethal acidic environment of the phagolysosome. Persistence of SCVs within host cells may explain failures in antimicrobial therapy and vaccinations.
Prosser S.,University of Guelph |
Martinez-Arce A.,Colegio de Mexico |
Elias-Gutierrez M.,Colegio de Mexico
Molecular Ecology Resources | Year: 2013
Despite the contribution of DNA barcoding towards understanding the biodiversity and distribution of species, the success of COI amplification has been quite variable when it comes to freshwater zooplankton (Elías-Gutiérrez & Valdez-Moreno 2008; Jeffery et al. 2011). Some genera of microcrustaceans seem to be more difficult to amplify than others. For example, Macrothrix, Scapholeberis, Diaphanosoma and cyclopoids have yielded limited results. Among several possible reasons for the inability to barcode freshwater microcrustaceans is that there does not exist a specific set of primers for COI amplification. To this end, we developed a zooplankton - specific set of primers, which significantly increased average amplification success (20% increase). With these primers, we observed an overall success of over 70% for Sididae and Chydoridae, and more than 80% for Daphniidae, Moinidae, Bosminidae, Macrothricidae, Ilyocryptidae and Diaptomidae. We also demonstrate a simple alteration to a common specimen fixation method that increases the overall recovery of barcodes from freshwater zooplankton. Collectively, we believe our results will greatly aid the recovery of barcodes from these difficult groups. © 2013 John Wiley & Sons Ltd.
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.
Dufresne F.,University of Quebec at Rimouski |
Stift M.,University of Konstanz |
Vergilino R.,University of Guelph |
Mable B.K.,University of Glasgow
Molecular Ecology | Year: 2014
Despite the importance of polyploidy and the increasing availability of new genomic data, there remain important gaps in our knowledge of polyploid population genetics. These gaps arise from the complex nature of polyploid data (e.g. multiple alleles and loci, mixed inheritance patterns, association between ploidy and mating system variation). Furthermore, many of the standard tools for population genetics that have been developed for diploids are often not feasible for polyploids. This review aims to provide an overview of the state-of-the-art in polyploid population genetics and to identify the main areas where further development of molecular techniques and statistical theory is required. We review commonly used molecular tools (amplified fragment length polymorphism, microsatellites, Sanger sequencing, next-generation sequencing and derived technologies) and their challenges associated with their use in polyploid populations: that is, allele dosage determination, null alleles, difficulty of distinguishing orthologues from paralogues and copy number variation. In addition, we review the approaches that have been used for population genetic analysis in polyploids and their specific problems. These problems are in most cases directly associated with dosage uncertainty and the problem of inferring allele frequencies and assumptions regarding inheritance. This leads us to conclude that for advancing the field of polyploid population genetics, most priority should be given to development of new molecular approaches that allow efficient dosage determination, and to further development of analytical approaches to circumvent dosage uncertainty and to accommodate 'flexible' modes of inheritance. In addition, there is a need for more simulation-based studies that test what kinds of biases could result from both existing and novel approaches. © 2013 John Wiley & Sons Ltd.
Gregori S.,University of Guelph
Electronics Letters | Year: 2010
A simple circuit design improves the driving capability of conventional voltage doublers and, at the same time, eliminates short-circuit losses. Simulation results confirm higher conversion efficiency and extended operation. © 2010 The Institution of Engineering and Technology.
Harauz G.,University of Guelph |
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.
Marshall S.A.,University of Guelph
Zootaxa | Year: 2013
The Caribbean and North American species of the large, otherwise neotropical genus Grallipeza Rondani (Diptera: Micropezidae: Taeniapterinae) are revised and keyed. One species, G. nebulosa (Loew), is endemic to the southeastern United States and eighteen species are endemic to single Caribbean islands. Of these, the following nine are described as new: Grallipeza abeja, G. albiterga, G. cliffi, G. grenada, G. marleyi, G. mellea, G. paraplacida, G. perezi and G. turba. Copyright © 2013 Magnolia Press.
Mutsaers A.J.,University of Guelph |
Walkley C.R.,St. Vincents Institute |
Walkley C.R.,University of Melbourne
Bone | Year: 2014
Osteosarcoma is a disease with many complex genetic abnormalities but few well defined genetic drivers of tumor initiation and evolution. The disease is diagnosed and defined through the observation of malignant osteoblastic cells that produce osteoid, however the exact cell of origin for this cancer remains to be definitively defined. Evidence exists to support a mesenchymal stem cell as well as committed osteoblast precursors as the cell of origin. Increasing numbers of experimental models have begun to shed light on to the likely cell population that gives rise to OS in vivo with the weight of evidence favoring an osteoblastic population as the cell of origin. As more information is gathered regarding osteosarcoma initiating cells and how they may relate to the cell of origin we will derive a better understanding of the development of this disease which may ultimately lead to clinical improvements through more personalized therapeutic approaches. © 2014 Elsevier Inc.
Woo P.T.K.,University of Guelph |
Ardelli B.F.,Brandon University
Developmental and Comparative Immunology | Year: 2014
This discussion is on immune response to Amyloodinium ocellatum, Cryptobia salmositica, Trypanoplasma borreli and Trypanosoma carassii. Piscidin and histone-like proteins enhance innate resistance to Amyloodinium. Fish that are naturally resistant to Cryptobia and Trypanoplasma can be bred. Cryptobia resistance in charr is controlled by a dominant Mendelian locus and protection is via the Alternative Pathway of Complement Activation. Studies on Cryptobia-tolerant charr may lead to production of transgenic Cryptobia-tolerant salmon. Innate response to T. borreli is associated with NO in macrophages. Transferrin regulates resistance and carp have been bred for transferrin genotypes. Recovered fish are protected from homologous challenge, and complement fixing antibodies are crucial in protection. Studies on antigens in T. carassii may lead to a vaccine. There are two vaccines against cryptobiosis; a single dose of the attenuated vaccine protects salmonids. On challenge fish inoculated with the metalloprotease-DNA vaccine do not have the disease and they recover faster. © 2013 Published by Elsevier Ltd.
Keller H.,University of Guelph |
Chambers L.,Scientist Elisabeth Bruyere Research Institute |
Niezgoda H.,Elisabeth Bruyere Research Institute
Journal of Nutrition, Health and Aging | Year: 2012
Use of modified texture foods (MTF) is common in the geriatric population. There is a potential for increased prevalence of use of MTF due in part to longer survival of persons with dementia, those who have suffered from a stroke, as well as other degenerative diseases that affect chewing and swallowing. Unfortunately, little clinical, nutritional and sensory research has been conducted on MTF to inform practice. This review highlights issues identified in the literature to date that influence nutritional and sensory quality and acceptability of these foods. Use of MTF is highly associated with undernutrition, however causality is difficult to demonstrate due to confounding factors such as the requirement for feeding assistance. Knowledge gaps and considerations that need to be taken into account when conducting research are identified.
Yap N.T.,University of Guelph
Impact Assessment and Project Appraisal | Year: 2016
The growth of unconventional shale gas development has been accompanied by controversy over its environmental and social impacts. This paper reviews recent literature to clarify what is known and not known about the physical, chemical and toxicological properties of the process chemicals and wastewaters generated in hydraulic fracturing, the mechanisms and pathways by which they enter surface water and groundwater aquifers and the risks posed to human and ecosystem health. Assessing the impacts of unconventional shale gas development is clearly constrained by a lack of baseline information, complex hydrogeological histories for natural migration of hydrocarbons, lack of tracers to monitor and verify the source, timing and mechanism of contaminant migration into water resources. This is compounded by lack of transparency and accountability in policy decisions. The paper argues that managing the social and environmental risks of unconventional shale gas development calls for a new generation of impact assessment, one that marries the ideals of strategic environmental assessment, cumulative effects assessment, backcasting and deliberative and inclusive processes of community engagement towards collective risk management. © 2016 IAIA
Sharom F.J.,University of Guelph
Frontiers in Oncology | Year: 2014
Multidrug resistance in cancer is linked to expression of the P-glycoprotein multidrug transporter (Pgp, ABCB1), which exports many structurally diverse compounds from cells. Substrates first partition into the bilayer and then interact with a large flexible binding pocket within the transporter's transmembrane regions. Pgp has been described as a hydrophobic vacuum cleaner or an outwardly directed drug/lipid flippase. Recent X-ray crystal structures have shed some light on the nature of the drug-binding pocket and suggested routes by which substrates can enter it from the membrane. Detergents have profound effects on Pgp function, and several appear to be substrates. Biochemical and biophysical studies in vitro, some using purified reconstituted protein, have explored the effects of the membrane environment. They have demonstrated that Pgp is involved in a complex relationship with its lipid environment, which modulates the behavior of its substrates, as well as various functions of the protein, including ATP hydrolysis, drug binding, and drug transport. Membrane lipid composition and fluidity, phospholipid headgroup and acyl chain length all influence Pgp function. Recent studies focusing on thermodynamics and kinetics have revealed some important principles governing Pgp-lipid and substrate-lipid interactions, and how these affect drug-binding and transport. In some cells, Pgp is associated with cholesterol-rich microdomains, which may modulate its functions. The relationship between Pgp and cholesterol remains an open question; however, it clearly affects several aspects of its function in addition to substrate-membrane partitioning. The action of Pgp modulators appears to depend on their membrane permeability, and membrane fluidizers and surfactants reverse drug resistance, likely via an indirect mechanism. A detailed understanding of how the membrane affects Pgp substrates and Pgp's catalytic cycle may lead to new strategies to combat clinical drug resistance. © 2014 Sharom.
Kernaghan S.,University of Guelph
Animal health research reviews / Conference of Research Workers in Animal Diseases | Year: 2012
The tonsil of the soft palate in pigs is a secondary lymphoid tissue that provides a first line of defense against foreign antigens entering by the mouth or nares. It has been known for a long time to be the site of colonization of important swine and zoonotic bacterial pathogens. Initially our understanding of microbes present at this site came from culture-based studies. Very recently, sequence-based approaches have been used to identify the core microbiome of the swine tonsil. Although animal to animal and herd to herd variation was detected in these studies, >90 of the organisms detected belonged to the phyla Proteobacteria and Firmicutes. Members of the family Pasteurellaceae appeared to be predominate in the tonsil; however, the relative proportions of Actinobacillus, Haemophilus, and Pasteurella varied. Members of the families Moraxellaceae, Fusobacteriaceae, Veillonellaceae, and Neisseriaceae were also seen as frequent residents of the tonsil.
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.
Josephy P.D.,University of Guelph
Human Genomics and Proteomics | Year: 2010
Glutathione transferase enzymes (GSTs) catalyze reactions in which electrophiles are conjugated to the tripeptide thiol glutathione. While many GST-catalyzed transformations result in the detoxication of xenobiotics, a few substrates, such as dihaloalkanes, undergo bioactivation to reactive intermediates. Many molecular epidemiological studies have tested associations between polymorphisms (especially, deletions) of human GST genes and disease susceptibility or response to therapy. This review presents a discussion of the biochemistry of GSTs, the sourcesboth genetic and environmentalof interindividual variation in GST activities, and their implications for pharmaco- and toxicogenetics; particular attention is paid to the Theta class GSTs. © 2010 P. David Josephy.
Harrison X.A.,University of Exeter |
Blount J.D.,University of Exeter |
Inger R.,University of Exeter |
Norris D.R.,University of Guelph |
Bearhop S.,University of Exeter
Journal of Animal Ecology | Year: 2011
Carry-over effects occur when processes in one season influence the success of an individual in the following season. This phenomenon has the potential to explain a large amount of variation in individual fitness, but so far has only been described in a limited number of species. This is largely due to difficulties associated with tracking individuals between periods of the annual cycle, but also because of a lack of research specifically designed to examine hypotheses related to carry-over effects. We review the known mechanisms that drive carry-over effects, most notably macronutrient supply, and highlight the types of life histories and ecological situations where we would expect them to most often occur. We also identify a number of other potential mechanisms that require investigation, including micronutrients such as antioxidants. We propose a series of experiments designed to estimate the relative contributions of extrinsic and intrinsic quality effects in the pre-breeding season, which in turn will allow an accurate estimation of the magnitude of carry-over effects. To date this has proven immensely difficult, and we hope that the experimental frameworks described here will stimulate new avenues of research vital to advancing our understanding of how carry-over effects can shape animal life histories. We also explore the potential of state-dependent modelling as a tool for investigating carry-over effects, most notably for its ability to calculate optimal rates of acquisition of a multitude of resources over the course of the annual cycle, and also because it allows us to vary the strength of density-dependent relationships which can alter the magnitude of carry-over effects in either a synergistic or agonistic fashion. In conclusion carry-over effects are likely to be far more widespread than currently indicated, and they are likely to be driven by a multitude of factors including both macro- and micronutrients. For this reason they could feasibly be responsible for a large amount of the observed variation in performance among individuals, and consequently warrant a wealth of new research designed specifically to decompose components of variation in fitness attributes related to processes across and within seasons. © 2010 The Authors. Journal compilation © 2010 British Ecological Society.
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.
Bowlby D.A.,University of Guelph
Neuroendocrinology | Year: 2015
Background/Aims: The contributions of the three principal ovarian steroid hormones (estradiol, progesterone and testosterone) to the regulation of estrogen receptor alpha (ERα) levels in the rat brain were examined during the estrous cycle. Methods: Receptor concentrations were measured using an in vitro autoradiographic technique designed to separately quantify free, unoccupied receptors and receptors ‘occupied' by (bound to) endogenous hormone. Results: ERα occupation increased at proestrus and declined at estrus, reflecting changes in circulating estradiol and testosterone levels. Total ERα content followed a pattern that was the inverse of the occupation data, falling over the night of proestrus. Between 2.00 and 10.00 a.m. on the day of estrus, total ERα concentrations recovered in all brain regions except the ventromedial nucleus (VMN), in which ERα binding remained depressed at estrus. Administration of the progesterone antagonist, mifepristone, on the afternoon of proestrus resulted in recovery of ERα levels in the VMN by the morning of estrus, consistent with the hypothesis that the preovulatory progesterone surge selectively inhibits VMN ERα expression. Residual ERα occupation observed at estrus, when estradiol is not detectable in the serum, likely reflects intracranial aromatization of circulating androgens, since the pattern of receptor occupation observed at this stage of the cycle could be reproduced in ovariectomized rats by replacement with testosterone. Conclusion: These findings indicate that ERα binding in the brain fluctuates during the rat estrous cycle in a region-specific manner and suggest that local aromatization of testosterone may contribute significantly to ERα occupation when circulating estradiol levels are low. © 2015 S. Karger AG, Basel Copyright © 2015, S. Karger AG. All rights reserved.
Deng Q.,TU Hamburg - Harburg |
Smetanin M.,University of Guelph |
Weissmuller J.,TU Hamburg - Harburg |
Weissmuller J.,Helmholtz Center Geesthacht
Journal of Catalysis | Year: 2014
Many modern catalyst materials exploit a strained surface layer as the active component. Here, we explore how the catalytic activity is affected by changes in the lattice parameter, focusing on the hydrogen evolution reaction on Au and Pt electrodes in H2SO4 as a model process. We present a lock-in technique that allows the modulation of the reaction current to be followed in situ while a small cyclic elastic strain is imposed on the electrode material. We find that tensile strain enhances the exchange current density and the reactivity at low overpotential, ΔE, whereas the trend is inverted and the reactivity diminished at higher ΔE. We introduce kinetic rate equations for Heyrowsky and Tafel kinetics, allowing for strain dependence of the hydrogen adsorption enthalpy as well as the activation enthalpy. The results link the reactivity modulation to electrocapillary coupling coefficients that are open to investigation by experiment or ab initio computation. The inversion in sign of the coupling as the function of ΔE emerges in agreement with experiment.© 2013 Elsevier Inc. All rights reserved.
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.
Griswold C.K.,University of Guelph
Proceedings of the Royal Society B: Biological Sciences | Year: 2015
A fundamental goal of the biological sciences is to determine processes that facilitate the evolution of diversity. These processes can be separated into ecological, physiological, developmental and genetic. An ecological process that facilitates diversification is frequency-dependent selection caused by competition. Models of frequency-dependent adaptive diversification have generally assumed a genetic basis of phenotype that is non-epistatic. Here, we present a model that indicates diversification is accelerated by an epistatic basis of phenotype in combination with a competition model that invokes frequencydependent selection. Our model makes use of a genealogical model of epistasis and insights into the effects of balancing selection on the genealogical structure of a population to understand how epistasis can facilitate diversification. The finding that epistasis facilitates diversification may be informative with respect to empirical results that indicate an epistatic basis of phenotype in experimental bacterial populations that experienced adaptive diversification. © 2015 The Author(s) Published by the Royal Society.
Bauch C.T.,University of Guelph
PloS one | Year: 2010
Mathematical models have formalized how free-rider effects can threaten the stability of high vaccine coverage levels under established voluntary vaccination programs. However, little research has addressed the question of when free-riding begins to develop when a new vaccine is first introduced in a population. Here, we combine a game theoretical model of vaccinating behavior with an age-structured compartmental model to analyze rational vaccinating behavior in the first years of a universal immunization program, where a new vaccine is free to all children of a specified age. The model captures how successive birth cohorts face different epidemiological landscapes that have been shaped by the vaccinating decisions of previous birth cohorts, resulting in a strategic interaction between individuals in different birth cohorts. The model predicts a Nash equilibrium coverage level of for the first few birth cohorts under the new program. However, free-riding behavior emerges very quickly, with the Nash equilibrium vaccine coverage dropping significantly within 2-5 years after program initiation. Subsequently, a rich set of coupled dynamics between infection prevalence and vaccinating behaviors is possible, ranging from relatively stable (but reduced) coverage in later birth cohorts to wide fluctuations in vaccine coverage from one birth cohort to the next. Individual tolerance for vaccine risk also starts out at relatively high levels before dropping significantly within a few years. These results suggest that even relatively new immunization programs can be vulnerable to drops in vaccine coverage caused by vaccine scares and exacerbated by herd immunity effects, necessitating vigilance from the start.
Plant growth and respiration re-visited: Maintenance respiration defined it is an emergent property of, not a separate process within, the system and why the respiration: Photosynthesis ratio is conservative
Thornley J.H.M.,University of Guelph
Annals of Botany | Year: 2011
Background and Aims: Plant growth and respiration still has unresolved issues, examined here using a model. The aims of this work are to compare the models predictions with McCrees observation-based respiration equation which led to the 'growth respiration/maintenance respiration paradigm' (GMRP) - this is required to give the model credibility; to clarify the nature of maintenance respiration (MR) using a model which does not represent MR explicitly; and to examine algebraic and numerical predictions for the respiration:photosynthesis ratio. • Methods: A two-state variable growth model is constructed, with structure and substrate, applicable on plant to ecosystem scales. Four processes are represented: photosynthesis, growth with growth respiration (GR), senescence giving a flux towards litter, and a recycling of some of this flux. There are four significant parameters: growth efficiency, rate constants for substrate utilization and structure senescence, and fraction of structure returned to the substrate pool. • Key Results: The model can simulate McCrees data on respiration, providing an alternative interpretation to the GMRP. The models parameters are related to parameters used in this paradigm. MR is defined and calculated in terms of the models parameters in two ways: first during exponential growth at zero growth rate; and secondly at equilibrium. The approaches concur. The equilibrium respiration:photosynthesis ratio has the value of 0·4, depending only on growth efficiency and recycling fraction. • Conclusions: McCrees equation is an approximation that the model can describe; it is mistaken to interpret his second coefficient as a maintenance requirement. An MR rate is defined and extracted algebraically from the model. MR as a specific process is not required and may be replaced with an approach from which an MR rate emerges. The model suggests that the respiration: photosynthesis ratio is conservative because it depends on two parameters only whose values are likely to be similar across ecosystems. © The Author 2011.
Bersenas A.M.,University of Guelph
Journal of Veterinary Emergency and Critical Care | Year: 2011
Objective: To review the principles and practice of peritoneal dialysis in veterinary medicine. Data Sources: Clinical and experimental studies and current guideline recommendations from the human literature; and original case studies, case reports, and previous reviews in the veterinary literature. Summary: Peritoneal dialysis involves the exchange of solutes and fluid between the peritoneal capillary blood and the dialysis solution across the peritoneal membrane. It requires placement of a peritoneal dialysis catheter for repeated dialysate exchange. The ideal catheter provides reliable, rapid dialysate flow rates without leaks or infections. Catheter selection and placement are reviewed along with dialysate selection, exchange prescriptions, and overall patient management. PD does not require specific or complex equipment, and it can achieve effective control of uremia and electrolyte imbalances. Conclusions: Peritoneal dialysis is a potential life-saving measure for patients with acute renal failure. Peritoneal dialysis results in gradual decline in uremic toxins. Previously low success rates have been reported. Improved success rates have been noted in dogs with acute kidney injury (AKI) secondary to leptospirosis. Cats also have a good success rate when PD is elected in patients with a potentially reversible underlying disease. Overall, PD remains a viable intervention for patients with AKI unresponsive to medical management. In select patients a favorable outcome is attained whereby PD provides temporary support until return of effective renal function is attained. © Veterinary Emergency and Critical Care Society 2011.
Scott Weese J.,University of Guelph
ILAR Journal | Year: 2010
Methicillin-resistant Staphylococcus aureus (MRSA) is a critically important human pathogen that is also an emerging concern in veterinary medicine and animal agriculture. It is present in a wide range of animal species, including dogs, cats, rabbits, horses, cattle, pigs, poultry, and exotic species, both as a cause of infection and in healthy carriers. Identification of MRSA in various species and in food has led to concerns about the roles of animals, both pets and livestock, in the epidemiology of MRSA infection and colonization in humans. There is evidence of the role of food animals in human MRSA infections in some countries and of pets as a possible source of human infection. Some groups of individuals who work closely with animals, such as veterinarians, have high MRSA colonization rates. This article includes discussions of MRSA in human medicine, animals, and food, as well as its interspecies transmission, colonization, infection, strains, and affected populations. However, clear answers are lacking in many of these areas and limited studies may lead to premature conclusions. It is certain that animals are a source of human MRSA infection in some circumstances-but humans may also serve as sources of infection in animals. Changes in the epidemiology of MRSA in one species may be reflected in changes in other species. The true scope of MRSA in animals and its impact on human health are still only superficially understood, but it is clear that MRSA is a potentially important veterinary and public health concern that requires a great deal more study to enhance understanding and effective response.
Wright D.C.,University of Guelph
Applied Physiology, Nutrition and Metabolism | Year: 2014
Owing to its obligatory role in locomotion and the fact that it accounts for the vast majority of whole-body glucose and lipid oxidation, much work has focused on studying the biochemical adaptations that occur in skeletal muscle in response to exercise. However, over the past several years there has been a growing appreciation that adipose tissue is an important player in regulating systemic carbohydrate and lipid homeostasis. Despite this, the examination of how exercise alters adipose tissue function and metabolism is, when compared with skeletal muscle, in its infancy. The purpose of the current review is to highlight some of the recent findings from our laboratory and others that focus on the emerging area of adipose tissue exercise biochemistry. Specifically, the role of exercise on the induction of mitochondrial and glyceroneogenic enzymes will be examined and will be compared with the well-characterized effects of thiazolidinediones, which are insulin-sensitizing drugs. A particular emphasis will be placed on the role of interleukin-6 in mediating the effects of exercise. Finally, we will discuss recent data from our laboratory demonstrating beneficial effects of resveratrol supplementation on adipose tissue metabolism.
Jeffery N.W.,University of Guelph
Polar Biology | Year: 2012
Krill (family Euphausiidae) represent some of the most abundant organisms in the both northern and southern oceanic environments and provide food for various animals including humans. Despite their importance, little is known about krill from a genomic standpoint, even with regard to basic properties such as total genome size. This study provides genome size estimates for six species of krill from both the North Atlantic and Southern Oceans which are the first such estimates for any species of euphausiid. Genome size estimates were obtained using both flow cytometry and Feulgen image analysis densitometry with chicken and trout blood as internal standards. Haploid genome sizes ranged from 12. 77 to 48. 53 pg, providing roughly fourfold variation within these six species alone. With such large estimates, sequencing of a krill genome will currently be costly and laborious, but further studies should be conducted to determine the composition of these exceptionally large genomes. © 2011 Springer-Verlag.
Alvarez D.,University of Murcia |
Barbut S.,University of Guelph
Meat Science | Year: 2013
The effects of fat level (20.0, 12.5 and 5.0%), Inulin (gel-IG, and powder-IP) and β-Glucan (βG) on emulsion stability, color, textural characteristics and microstructure of cooked meat batters were investigated. Reducing fat to 5.0% increased cooking loss and decreased emulsion stability, lightness, hardness and fracturability of cooked emulsions. Inulin, βG, and their mixtures were used as fat replacers in low fat formulations. Adding IP provided better emulsion stability compared to IG, which had no significant effect on stability. IP also produced harder (27-34. N) low fat products with a high fracturability (26-29. N). On the contrary, emulsions containing IG resulted in creamy and softer characteristics. The results were supported by light micrographs, which indicated that appropriate addition of IG and βG mixtures (3%-IG & 0.3%-βG, 6%-IG & 0.6%-βG) could compensate for some of the changes brought about by fat reduction, and maintained several of the textural characteristics of the product as well as reducing cook loss. © 2013 Elsevier Ltd.
Ford A.T.,University of Guelph |
Goheen J.R.,University of Wyoming
Trends in Ecology and Evolution | Year: 2015
Studies on trophic cascades involving large carnivores typically are limited by a lack of replication and control, giving rise to a spirited debate over the ecological role of these iconic species. We argue that much of this debate can be resolved by decomposing the trophic cascade hypothesis into three constituent interactions, quantifying each interaction individually, and accommodating alternative hypotheses. We advocate for a novel approach that couples the rigor characterizing foundational work on trophic cascades (i.e., from studies carried out in mesocosm and whole lake systems) with the conservation relevance of large carnivore-dominated food webs. Because of their iconic status, it is crucial that inferences about the ecological role of large carnivores rise to meet the same rigorous standards to which other studies in community ecology are held. Large carnivores are believed to play a key role in determining ecosystem properties via trophic cascades. While the recovery of large carnivore populations is generally heralded as a conservation success story, the common assertion that such recoveries alter plant communities and other ecosystem properties is currently not supported by the standards of evidence expected in other scientific disciplines.There have been very few replicated and controlled experiments documenting evidence for trophic cascades involving large carnivores, leaving a knowledge gap with crucial implications for ecology and wildlife conservation.The absence of a mechanistic understanding of food web dynamics and weak inference in many studies combine to obfuscate the mechanisms underlying if and how large carnivores affect ecosystems. © 2015 Elsevier Ltd.
Wright P.A.,University of Guelph
Integrative and Comparative Biology | Year: 2012
The mangrove rivulus (Kryptolebias marmoratus) is an excellent model species for understanding the physiological mechanisms that fish use in coping with extreme environmental conditions, particularly cutaneous exchange during prolonged exposure to air. Their ability to self-fertilize and produce highly homozygous lineages provides the potential for examining environmental influences on structures and related functions without the complications of genetic variation. Over the past 10 years or so, we have gained a broader understanding of the mechanisms K. marmoratus use to maintain homeostasis when out of water for days to weeks. Gaseous exchange occurs across the skin, as dramatic remodeling of the gill reduces its effective surface area for exchange. Ionoregulation and osmoregulation are maintained in air by exchanging Na +, Cl-, and H2O across skin that contains a rich population of ionocytes. Ammonia excretion occurs in part by cutaneous NH3 volatilization facilitated by ammonia transporters on the surface of the epidermis. Finally, new evidence indicates that cutaneous angiogenesis occurs when K. marmoratus are emersed for a week, suggesting a higher rate of blood flow to surface vessels. Taken together, these and other findings demonstrate that the skin of K. marmoratus takes on all the major functions attributed to fish gills, allowing them to move between aquatic and terrestrial environments with ease. Future studies should focus on variation in response to environmental changes between homozygous lineages to identify the genetic underpinnings of physiological responses. © 2012 The Author 2012. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: email@example.com.
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.
Wenger L.M.,University of Guelph
American Journal of Men's Health | Year: 2011
Although the literature on men's help seeking offers important insights into health service engagement patterns within this population, there remain gaps in our understanding. In addition to insufficient attention to a range of male experiences and a restricted focus on sex-specific or associated diseases, much of the extant work is limited by insufficient attention to how men navigate needs and supports across illness and a narrow conceptualization of the core concept of help seeking. Specifically, as research focuses on masculinity as a determinant of the decision to seek medical help (emphasis on prediction), less is known about how men, as gendered beings, are experiencing help seeking over the course of illness (emphasis on understanding). In this article, it is argued that research on men's help seeking can benefit from the integration of a dynamic conceptualization of help seeking that is considerate of shifting needs and a diversity of supports and which emphasizes the subjective, interactive, and ongoing patterns in how men are perceiving, interpreting, and responding to the challenges of illness. © The Author(s) 2011.
McKitrick R.,University of Guelph
Climatic Change | Year: 2013
The debate over whether urbanization and related socioeconomic developments affect large-scale surface climate trends is stalemated with incommensurable arguments. Each side can appeal to supporting evidence based on statistical models that do not overlap, yielding inferences that merely conflict but do not refute one another. I argue that such debates are only be resolved in an encompassing framework, in which both types of results can be demonstrated as restricted forms of the same statistical model, and the restrictions can be tested. The issues under debate make such data sets challenging to construct, but I give two illustrative examples. First, insignificant differences in warming trends in urban temperature data during windy and calm conditions are shown in a restricted model whose general form shows temperature data to be strongly affected by local population growth. Second, an apparent equivalence between trends in a data set stratified by a static measure of urbanization is shown to be a restricted finding in a model whose general form indicates significant influence of local socioeconomic development on temperatures. © 2013 Springer Science+Business Media Dordrecht.
Kutcher H.R.,Agriculture and Agri Food Canada |
Warland J.S.,University of Guelph |
Brandt S.A.,Agriculture and Agri Food Canada
Agricultural and Forest Meteorology | Year: 2010
Adverse weather is often associated with yield reduction of canola, also known as oilseed rape. Historical weather and crop yield data from Saskatchewan (SK) crop districts were analyzed with both simple correlation analysis and iterative principal components analysis. The analyses demonstrated the negative impacts of high temperatures and low precipitation, and the positive effects of greater-than-average precipitation, and to a lesser extent, cooler-than-average nocturnal temperatures. Iterative Chi-square analysis and iterative principal components analysis both showed that the beginning of July, which coincides with the early part of the flowering period of the crop in SK, was the critical time in which high temperatures (>30 °C) and low precipitation led to yield loss. Crown Copyright © 2009.
Fraser E.D.G.,University of Guelph
Global Environmental Change | Year: 2013
This paper examines four broad policy and public responses to the American Dust Bowl in the 1930s as a way of exploring how society today could address our own "food crisis". More particularly, in the Dust Bowl some argued that solutions would be found by engineers and farmers who would develop new ways of watering dry fields. A second group believed that inappropriate political and economic incentives had led to bad farming practices prior to the drought and this contributed to wide-spread erosion. To this group, the best solutions included governmental regulation of farm practices. A third group focused on the welfare of individuals, arguing that creating a social safety net to protect marginalized families was the highest priority. Finally, there were commentators who advocated for a smaller scale, ecological, and holistic approach to farming. Today, the same four perspectives are present in debates about how to maintain global food security in light of population growth, high energy prices and climate change. Exploring the similarity of the discourses between today's food crisis and the one that hit American society 80 years ago reveals that advocates of the four different camps are motivated by very different principles. Briefly, proponents of technological solutions base many of their arguments on the assumption that human ingenuity is capable of producing extremely productive food systems. The managerial arguments, by contrast, are based on the idea that the natural environment can be rationally and efficiently managed using scientific principles. The social welfare narrative seeks to create a more equitable food system. Finally, the ecological and holistic narrative argues that diverse, small scale and local food systems are a prerequisite for long term sustainability. The primary contribution of this paper, therefore, is to expose these deeply held ontological tensions as a way of arguing that policy makers today must de-politicise arguments and use the principles embedded in all four narratives when designing programmes to ensure that the 21st century does not face a repeat of the crisis of the 1930s. © 2013 Elsevier Ltd.
Ali S.I.,University of Guelph
Journal of Water and Health | Year: 2010
In response to rapid urbanization throughout the global South, urban and peri-urban slums are expanding at an alarming rate. Owing to inadequate financial and institutional resources at the municipal level, conventional approaches for safe water provision with centralized treatment and distribution infrastructure have been unable to keep pace with rapidly growing demand. In the absence of alternatives to centralized systems, a global public health emergency of infectious water-related diseases has developed. Alternative decentralized water treatment systems have been promoted in recent years as a means of achieving rapid health gains among vulnerable populations. Though much work with decentralized systems, especially in urban environments, has been at the household level, there is also considerable potential for development at the community level. Both levels of approach have unique sets of advantages and disadvantages that, just as with treatment technologies, may make certain options more appropriate than others in a particular setting. Integrating community, government and other relevant stakeholders into the process of systems development and implementation is essential if the outcome is to be appropriate to local circumstances and sustainable in the long term. © IWA Publishing 2010.
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.
Swatland H.J.,University of Guelph
Meat Science | Year: 2010
Meat products and consumption culture in the West may be traced back for at least 2,500 years. The dominant cultural source was Greco-Roman, with evidence from archeology, surviving documents and the names of meat cuts. The initial uniformity of meat technology and language in the Roman Empire was lost as national boundaries and languages fragmented. More recently, however, there has been a strong trend back to uniformity in meat cutting and grading. This started in the USA to solve logistical problems associated with long-distance commerce and similar changes occurred with the formation of the EU. Issues such as meat inspection and animal transport have been strongly influenced by the effect of literature on public opinion, which then led to legislated improvements. Innovations in other areas such as meat distribution and preservation had military origins. Meat consumption culture was involved in the early development of language, social grouping and religions. © 2010 The American Meat Science Association.
Green S.R.,University of Guelph |
Wald R.M.,University of Chicago
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013
In previous work, we introduced a new framework to treat large-scale backreaction effects due to small-scale inhomogeneities in general relativity. We considered one-parameter families of spacetimes for which such backreaction effects can occur, and we proved that, provided the weak energy condition on matter is satisfied, the leading effect of small-scale inhomogeneities on large-scale dynamics is to produce a traceless effective stress-energy tensor that itself satisfies the weak energy condition. In this work, we illustrate the nature of our framework by providing two explicit examples of one-parameter families with backreaction. The first, based on previous work of Berger, is a family of polarized vacuum Gowdy spacetimes on a torus, which satisfies all of the assumptions of our framework. As the parameter approaches its limiting value, the metric uniformly approaches a smooth background metric, but spacetime derivatives of the deviation of the metric from the background metric do not converge uniformly to zero. The limiting metric has nontrivial backreaction from the small-scale inhomogeneities, with an effective stress energy that is traceless and satisfies the weak energy condition, in accord with our theorems. Our second one-parameter family consists of metrics which have a uniform Friedmann-Lemaître-Robertson-Walker limit. This family satisfies all of our assumptions with the exception of the weak energy condition for matter. In this case, the limiting metric has an effective stress-energy tensor which is not traceless. We emphasize the importance of imposing energy conditions on matter in studies of backreaction. © 2013 American Physical Society.
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.
Case A.L.,Kent State University |
Caruso C.M.,University of Guelph
New Phytologist | Year: 2010
In many gynodioecious plants, sex is determined by cytoplasmic male sterility genes (CMS) and nuclear male fertility restorers (Rf). Models predict that the costs of restoration are important determinants of population sex ratios. However, current approaches to the estimation of these costs require prior identification of CMS genotypes, information that is available for few species.We tested a novel approach to estimating the cost of restoration in natural populations without determining CMS or Rf genotypes. We used estimates of pollen viability and offspring sex ratios from open- and hand-pollinated families of Lobelia siphilitica to test whether the cost of restoration, expressed as low pollen viability, is higher in populations with more females.Among populations with CMS, we found that variation in pollen viability was higher in small populations with more females, as expected if the proportion of females within populations increases with the maximum cost of restoration. In controlled crosses, families with low pollen viability also produced fewer females, suggesting that variation in viability is primarily determined by the number and frequency of Rf alleles carried.This approach to estimating the cost of restoration can be applied to other cytonuclear gynodioecious species, offering new opportunities for testing gynodioecy models in the wild. © The Authors (2010). Journal compilation © New Phytologist Trust (2010).
Mckitrick R.,University of Guelph
Atmospheric Science Letters | Year: 2010
We explain panel and multivariate regressions for comparing trends in climate data sets. They impose minimal restrictions on the covariance matrix and can embed multiple linear comparisons, which is a convenience in applied work. We present applications comparing post-1979 modeled and observed temperature trends in the tropical lower- and mid-troposphere. Results are sensitive to the sample length. In data spanning 1979-1999, observed trends are not significantly different from zero or from model projections. In data spanning 1979-2009, the observed trends are significant in some cases but tend to differ significantly from modeled trends. Copyright © 2010 Royal Meteorological Society.
Irving J.,University of Guelph |
Holliger K.,University of Lausanne
Geophysical Research Letters | Year: 2010
Estimation of the spatial statistics of subsurface velocity heterogeneity from surface-based geophysical reflection survey data is a problem of significant interest in seismic and ground-penetrating radar (GPR) research. A method to effectively address this problem has been recently presented, but our knowledge regarding the resolution of the estimated parameters is still inadequate. Here we examine this issue using an analytical approach that is based on the realistic assumption that the subsurface velocity structure can be characterized as a band-limited scale-invariant medium. Our work importantly confirms recent numerical findings that the inversion of seismic or GPR reflection data for the geostatistical properties of the probed subsurface region is sensitive to the aspect ratio of the velocity heterogeneity and to the decay of its power spectrum, but not to the individual values of the horizontal and vertical correlation lengths. © 2010 by the American Geophysical Union.
Gaufichon L.,French National Institute for Agricultural Research |
Rothstein S.J.,University of Guelph |
Suzuki A.,French National Institute for Agricultural Research
Plant and Cell Physiology | Year: 2016
Inorganic nitrogen in the form of ammonium is assimilated into asparagine via multiple steps involving glutamine synthetase (GS), glutamate synthase (GOGAT), aspartate aminotransferase (AspAT) and asparagine synthetase (AS) in Arabidopsis. The asparagine amide group is liberated by the reaction catalyzed by asparaginase (ASPG) and also the amino group of asparagine is released by asparagine aminotransferase (AsnAT) for use in the biosynthesis of amino acids. Asparagine plays a primary role in nitrogen recycling, storage and transport in developing and germinating seeds, as well as in vegetative and senescence organs. A small multigene family encodes isoenzymes of each step of asparagine metabolism in Arabidopsis, except for asparagine aminotransferase encoded by a single gene. The aim of this study is to highlight the structure of the genes and encoded enzyme proteins involved in asparagine metabolic pathways; the regulation and role of different isogenes; and kinetic and physiological properties of encoded enzymes in different tissues and developmental stages. © 2015 The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.
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.
Vyn R.J.,University of Guelph
Canadian Journal of Agricultural Economics | Year: 2012
Marketing decisions can be some of the most difficult decisions facing grain and oilseed producers. There is a lack of information about the marketing strategies that are most effective, and there is also a lack of consensus in the literature about whether some types of marketing strategies can consistently perform better than others. This paper uses a simulation model based on daily cash and futures prices to compare returns and risk over time from specific marketing strategies for corn and soybean producers in Ontario. This paper also examines whether there are differences in the relative effectiveness of strategies between higher-price years and lower-price years. The results indicate that preharvest marketing strategies for both corn and soybeans tend to generate prices that are much higher than selling everything at harvest (the baseline strategy), particularly for the higher-price years; however, these differences are not always statistically significant. Preharvest strategies are also found to reduce downside risk relative to the baseline. © 2012 Canadian Agricultural Economics Society.
Saibene D.,Pennsylvania State University |
Seetharaman K.,University of Guelph
Carbohydrate Polymers | Year: 2010
The granular organization of common corn and potato starch is characteristically different. The objective of this study was to investigate iodine complex formation with starch lintners from common corn starch (CCS) and potato starch (PS) litners as a function of water content. Starches were subjected to mild acid hydrolysis (lintnerization). Size exclusion chromatography of the lintners indicated that the linear chains remaining after lintnerization had smaller degree of polymerization in PS lintners than in the corresponding CCS lintners. For both CCS and PS, the absorbance intensity and the wavelength of maximum absorption (λmax) of molecularly dispersed starches, in diluted iodine solution, decreased with increasing lintnerization extent. When the granular lintners were exposed to iodine vapor, following equilibration to different moisture contents, the reduction in the iodine binding was evident in PS lintners but not in CCS lintners. Furthermore, the iodination partially destroyed the crystallinity of native PS granules but not that of CCS granules. However, B-type crystallinity was still evident in PS lintners. This behavior was attributed to different location of amylose within starch granules, supporting the involvement of amylose in the B-type crystallites of PS, and the independence of amylose from the A-type crystallites of CCS.
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.
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.
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.
Weese J.S.,University of Guelph
Clinical Microbiology and Infection | Year: 2010
Clostridium difficile is a critically important cause of disease in humans, particularly in hospitalized individuals. Three major factors have raised concern about the potential for this pathogen to be a cause of foodborne disease: the increasing recognition of community-associated C. difficile infection, recent studies identifying C. difficile in food animals and food, and similarities in C. difficile isolates from animals, food and humans. It is clear that C. difficile can be commonly found in food animals and food in many regions, and that strains important in human infections, such as ribotype 027/NAP1/toxinotype III and ribotype 078/toxinotype V, are often present. However, it is currently unclear whether ingestion of contaminated food can result in colonization or infection. Many questions remain unanswered regarding the role of C. difficile in community-associated diarrhoea: its source when it is a food contaminant, the infective dose, and the association between ingestion of contaminated food and disease. The significant role of this pathogen in human disease and its potential emergence as an important community-associated pathogen indicate that careful evaluation of different sources of exposure, including food, is required, but determination of the potential role of food in C. difficile infection may be difficult. © 2009 The Author. Journal Compilation © 2009 European Society of Clinical Microbiology and Infectious Diseases.
Quick V.,U.S. National Institutes of Health |
Wall M.,Second Street |
Larson N.,Second Street |
Haines J.,University of Guelph |
Neumark-Sztainer D.,Second Street
International Journal of Behavioral Nutrition and Physical Activity | Year: 2013
Background: The objective of this study was to identify 10-year longitudinal predictors of overweight incidence during the transition from adolescence to young adulthood.Methods: Data were from Project EAT (Eating and Activity in Teens and Young Adults). A diverse, population-based cohort (N = 2,134) completed baseline surveys in 1998-1999 (mean age = 15.0±1.6, 'adolescence') and follow-up surveys in 2008-2009 (mean age = 25.4±1.7, 'young adulthood'). Surveys assessed personal, behavioral and socio-environmental factors hypothesized to be of relevance to obesity, in addition to height and weight. Multivariable logistic regression was used to estimate the adjusted odds for each personal, behavioral and socio-environmental factor at baseline, and 10-year changes for these factors, among non-overweight adolescents (n = 1,643) being predictive of the incidence of overweight (BMI ≥ 25) at 10-year follow-up.Results: At 10-year follow-up, 51% of young adults were overweight (26% increase from baseline). Among females and males, higher levels of body dissatisfaction, weight concerns, unhealthy weight control behaviors (e.g., fasting, purging), dieting, binge eating, weight-related teasing, and parental weight-related concerns and behaviors during adolescence and/or increases in these factors over the study period predicted the incidence of overweight at 10-year follow-up. Females with higher levels of whole grain intake and breakfast and dinner consumption frequency during adolescence were protected against becoming overweight. Among males, increases in vegetable intake protected against the incidence of overweight 10 years later.Conclusions: Findings suggest that obesity prevention interventions for adolescents should address weight-specific factors from within the domains of personal, behavioral, and socio-environmental factors such as promoting positive body image, decreasing unhealthy weight control behaviors, and limiting negative weight talk. © 2013 Quick et al.; licensee BioMed Central Ltd.
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.
Zakharov A.V.,Russian Academy of Sciences |
Sullivan D.E.,University of Guelph
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010
We have carried out a numerical study of both the structural and thermodynamic properties of free-standing smectic films (FSSFs) for two cases of enhanced pair interactions in the bounding layers. Calculations, based upon the extended McMillan's approach with anisotropic forces, shows a stepwise reduction of the value of the heat capacity as the temperature is raised above the bulk smectic A-isotropic transition. The effects of surface "enhanced" pair interactions in the bounding layers and of film thickness on the orientational and translational order parameters, the Helmholtz free energy, and entropy of FSSFs have also been investigated. Reasonable agreement between the theoretically predicted and the experimentally obtained-by means of calorimetric techniques-data on the heat capacity of the partially fluorinated 5-n-alkyl-2-(4-n-(perfluoroalkyl-metheleneoxy)phenyl) (H10F5MOPP) films has been obtained. © 2010 The American Physical Society.
Purslow P.P.,University of Guelph
Annual Review of Food Science and Technology | Year: 2014
Intramuscular connective tissue (IMCT) forms a series of continuous networks integrating muscle fibers and fascicles into a whole organ. The contributions of IMCT to cooked meat toughness have long been recognized. This review concentrates on (a) the potential to manipulate IMCT in the growing animal, (b) postmortem effects on structure and properties of IMCT, and (c) developments in techniques to quantify IMCT in meat. A new hypothesis can explain why IMCT is enzymatically degraded in postmortem aging; however, after cooking, no differences are seen in the IMCT contribution to toughness. This hypothesis proposes that heat-insoluble collagen occurs in a weak pool and a strong pool, where the weak pool is most easily degraded by both proteolysis and heat. Far from being a constant background feature, the IMCT contribution to cooked meat toughness can be varied and deserves fresh research on how to achieve this. Copyright © 2014 by Annual Reviews.
Hunter R.C.,University of Guelph
Canadian journal of microbiology | Year: 2010
Environmental growth conditions and cell physiology have the potential to influence bacterial surface-metal interactions in both planktonic and biofilm systems. Here, Pseudomonas aeruginosa was studied to determine the influence of these factors (pH, redox potential, and active respiration) on surface electrostatics and metal immobilization. Acid-base titrations revealed a decrease in ionizable ligands at pKa 5 (putative carboxyls) in cells grown below pH 6.2 and in cells grown anaerobically relative to cells grown under oxic and circumneutral pH conditions. This observation correlates with Western immunoblotting assays that revealed a reduction in carboxylated B-band lipopolysaccharide in these cells. Furthermore, spectrophotometric analysis revealed a decrease in zinc, copper, and iron immobilization in these cells, suggesting that lipopolysaccharide modification in response to environmental stimuli influences metal binding. The effect of active versus inactive metabolism on metal adsorption was also examined using respiration inhibitors carbonyl cyanide m-chlorophenylhydrazone and sodium azide. Cells treated with these compounds bound more zinc, copper, and iron than untreated controls, suggesting proton extrusion through respiration competes with metal cations for reactive groups on the cell surface. Accumulation of gold did not show the same trend, and transmission electron microscopy studies confirmed it was not a surface-mediated process. These results suggest that variations in growth environment and cell physiology influence metal accumulation by bacterial cell surfaces and may help to explain discontinuous accumulation of metal observed throughout microbial communities.
Corry R.,University of Guelph
Landscape Research | Year: 2014
Farming in Canada and the USA is dominated by row cropping concentrated in central regions. Using the Corn Belt of Iowa and the Lake Erie Lowlands of Ontario-sources of pollution affecting the Gulf of Mexico and Great Lakes-as exemplary regions, this paper provides a retrospective review of the landscape effects of policies and practices related to environmental stewardship and agricultural trade. Conservation policies and typical farm practices are described and compared for the two regions with an emphasis on lasting beneficial environmental outcomes. Connections among land cover changes, environmental consequences, and changes in environmental and trade policies and programs are considered along with future changes in farm management, trade liberalisation, and farm revenue sources. The paper concludes with prospective ideas of how policies and practices can maintain or enhance environmental benefits within intensively farmed landscapes as best approaches for agriculture. © 2013 © 2013 Landscape Research Group Ltd.
Varela N.P.,University of Guelph
Animal health research reviews / Conference of Research Workers in Animal Diseases | Year: 2013
This paper reviews information on antimicrobial resistance patterns and prudent use of antimicrobials to reduce the impact and spread of resistant Streptococcus suis strains. S. suis is an important pathogen in swine, which can cause significant economic loss. Prudent use of antimicrobials for S. suis is essential to preserve the therapeutic efficacy of broad-spectrum antimicrobials and to minimize selection of resistant S. suis strains. Resistance of S. suis to antimicrobials commonly used in swine, including lincosamides, macrolides, sulphonamides, and tetracycline, has been documented worldwide, with resistance in up to 85% of strains. Among antimicrobials examined, resistance of S. suis has been demonstrated to be relatively low for penicillin (0-27%), ampicillin (0.6-23%), and ceftiofur (0-23%). For penicillin, this result may be due in part to the unique mechanism by which resistance is acquired through modifications in the structure of penicillin-binding proteins. Recommendations to control S. suis infection include focused and careful choice and appropriate use of antimicrobials, together with preventive measures intended to improve swine management.
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.
Sharom F.J.,University of Guelph
IUBMB Life | Year: 2011
The rapid movement of polar lipids from one membrane leaflet to the other is facilitated by lipid flippases or translocases. Although their activity was first observed over 30 years ago, the structures, physiological roles, and molecular mechanisms of this group of proteins remain enigmatic. Lipid flippases maintain membrane lipid asymmetry, and in eukaryotes they are also intimately involved in membrane budding and vesicle trafficking. The ATP-dependent flippases are members of well-characterized protein families, whose other members transport nonlipid substrates across cell membranes. The P 4-type ATPases carry out the inward translocation of phospholipids, and various ABC transporters are involved in outward lipid movement. The ATP-independent flippases move lipid substrates in both directions between membrane leaflets. With only a few exceptions, the molecular identity of these proteins is still unknown, despite their involvement in key biosynthetic pathways in both bacteria and eukaryotes. This review provides an overview of the different classes of flippases, and summarizes recent progress in their identification and functional characterization. The possible mechanisms of action of lipid flippases are discussed, and future directions explored. © 2011 International Union of Biochemistry and Molecular Biology, Inc.
DeVries T.J.,University of Guelph |
Gill R.M.,Liquid Feeds International Ltd.
Journal of Dairy Science | Year: 2012
This study was designed to determine the effect of adding a molasses-based liquid feed (LF) supplement to a total mixed ration (TMR) on the feed sorting behavior and production of dairy cows. Twelve lactating Holstein cows (88.2 ± 19.5 DIM) were exposed, in a crossover design with 21-d periods, to each of 2 treatment diets: 1) control TMR and 2) control TMR with 4.1% dietary dry matter LF added. Dry matter intake (DMI), sorting, and milk yield were recorded for the last 7 d of each treatment period. Milk samples were collected for composition analysis for the last 3 d of each treatment period; these data were used to calculate 4% fat-corrected milk and energy-corrected milk yield. Sorting was determined by subjecting fresh feed and orts samples to particle separation and expressing the actual intake of each particle fraction as a percentage of the predicted intake of that fraction. Addition of LF did not noticeably change the nutrient composition of the ration, with the exception of an expected increase in dietary sugar concentration (from 4.0 to 5.4%). Liquid feed supplementation affected the particle size distribution of the ration, resulting in a lesser amount of short and a greater amount of fine particles. Cows sorted against the longest ration particles on both treatment diets; the extent of this sorting was greater on the control diet (55.0 vs. 68.8%). Dry matter intake was 1.4. kg/d higher when cows were fed the LF diet as compared with the control diet, resulting in higher acid-detergent fiber, neutral-detergent fiber, and sugar intakes. As a result of the increased DMI, cows tended to produce 1.9. kg/d more milk and produced 3.1 and 3.2. kg/d more 4% fat-corrected milk and energy-corrected milk, respectively, on the LF diet. As a result, cows tended to produce more milk fat (0.13. kg/d) and produced more milk protein (0.09. kg/d) on the LF diet. No difference between treatments was observed in the efficiency of milk production. Overall, adding a molasses-based LF to TMR can be used to decrease feed sorting, enhance DMI, and improve milk yield. © 2012 American Dairy Science Association.
Hawley J.A.,RMIT University |
Burke L.M.,Australian Institute of Sport |
Phillips S.M.,McMaster University |
Spriet L.L.,University of Guelph
Journal of Applied Physiology | Year: 2011
Skeletal muscle displays remarkable plasticity, enabling substantial adaptive modifications in its metabolic potential and functional characteristics in response to external stimuli such as mechanical loading and nutrient availability. Contraction-induced adaptations are determined largely by the mode of exercise and the volume, intensity, and frequency of the training stimulus. However, evidence is accumulating that nutrient availability serves as a potent modulator of many acute responses and chronic adaptations to both endurance and resistance exercise. Changes in macronutrient intake rapidly alter the concentration of blood-borne substrates and hormones, causing marked perturbations in the storage profile of skeletal muscle and other insulin-sensitive tissues. In turn, muscle energy status exerts profound effects on resting fuel metabolism and patterns of fuel utilization during exercise as well as acute regulatory processes underlying gene expression and cell signaling. As such, these nutrient-exercise interactions have the potential to activate or inhibit many biochemical pathways with putative roles in training adaptation. This review provides a contemporary perspective of our understanding of the molecular and cellular events that take place in skeletal muscle in response to both endurance and resistance exercise commenced after acute and/or chronic alterations in nutrient availability (carbohydrate, fat, protein, and several antioxidants). Emphasis is on the results of human studies and how nutrient provision (or lack thereof) interacts with specific contractile stimulus to modulate many of the acute responses to exercise, thereby potentially promoting or inhibiting subsequent training adaptation. Copyright © 2011 the American Physiological Society.
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.
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.
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.
Costa M.C.,University of Guelph
Animal health research reviews / Conference of Research Workers in Animal Diseases | Year: 2012
The equine intestinal tract contains a complex microbial population (microbiota) that plays an important role in health and disease. Despite the undeniable importance of a 'normal' microbiota, understanding of the composition and function of this population is currently limited. As methods to characterize the microbiota and its genetic makeup (the microbiome) have evolved, the composition and complexity of this population are starting to be revealed. As is befitting a hindgut fermenter, members of the Firmicutes phylum appear to predominate, yet there are significant populations of numerous other phyla. The microbiome appears to be profoundly altered in certain disease states, and better understanding of these alterations may offer hope for novel preventive and therapeutic measures. The development and increasing availability of next generation sequencing and bioinformatics methods offer a revolution in microbiome evaluation and it is likely that significant advances will be made in the near future. Yet, proper use of these methods requires further study of basic aspects such as optimal testing protocols, the relationship of the fecal microbiome to more proximal locations where disease occurs, normal intra- and inter-horse variation, seasonal variation, and similar factors.
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.
Keller H.H.,University of Waterloo |
Duizer L.M.,University of Guelph
Journal of Nutrition in Gerontology and Geriatrics | Year: 2014
Twelve focus groups were conducted in five sites with 80 allied health providers to identify their perspectives on providing pureed food to consumers. Thematic care analysis was completed to summarize and interpret these data. Providers' greatest concern was keeping consumers safe, and the right texture was prioritized over sensory appeal and acceptance. Providers recognized that these foods impacted the quality of life of consumers and worked to rationalize these diets with residents/patients and their families. In addition, offering foods they knew to be poorly accepted affected their self-concept as providers. As a result of these challenges, they did whatever they could in the kitchen and tableside to promote intake of pureed foods. Those in the "food chain" of pureed food provision suggested several ways to further improve these products. Greater communication between those who assist consumers with eating and those who produce the pureed food they consume is needed to promote acceptable pureed products. © 2014 Copyright Taylor & Francis Group, LLC.
Barclay P.,University of Guelph
Behavioral and Brain Sciences | Year: 2012
While admirable, Guala's discussion of reciprocity suffers from a confusion between proximate causes (psychological mechanisms triggering behaviour) and ultimate causes (evolved function of those psychological mechanisms). Because much work on strong reciprocity commits this error, I clarify the difference between proximate and ultimate causes of cooperation and punishment. I also caution against hasty rejections of wide readings of experimental evidence. © 2012 Cambridge University Press.
Chatziioannou K.,Montana State University |
Poisson E.,University of Guelph |
Yunes N.,Montana State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013
We calculate the linear vacuum perturbations of a Kerr black hole surrounded by a slowly varying external spacetime to third order in the ratio of the black-hole mass to the radius of curvature of the external spacetime. This expansion applies to two relevant physical scenarios: (i) a small Kerr black hole immersed in the gravitational field of a much larger external black hole, and (ii) a Kerr black hole moving slowly around another external black hole of comparable mass. This small-hole/slow-motion approximation allows us to parametrize the perturbation through slowly varying, time-dependent electric and magnetic tidal tensors, which then enable us to separate the Teukolsky equation and compute the Newman-Penrose scalar analytically to third order in our expansion parameter. We obtain generic expressions for the mass and angular momentum flux through the perturbed black hole horizon, as well as the rate of change of the horizon surface area, in terms of certain invariants constructed from the electric and magnetic tidal tensors. We conclude by applying these results to the second scenario described above. © 2013 American Physical Society.
Dey T.,University of Guelph
LWT - Food Science and Technology | Year: 2013
A novel food-grade oleogel made of cellulosic polymer, surfactant and oil is being proposed, which can act as a trans-fat substitute. While cellulosic polymer is responsible for thermal gelation as well as fiber reinforcement, surfactant acts as plasticizer and oil gets entrapped inside the gel structure. The surfactants were varied structure-wise and the oils under study had different fatty acid profiles. Viscoelastic parameters of the gels were correlated to polymer viscosity, surfactant structure and oil composition. Sorbitan monostearate and glycerol monooleate imparted the maximum and minimum gel strengths respectively (G′ = 39,570 Pa and 264.70 Pa), rest of the surfactants contributing in between. Oleic acid containing surfactants offered more plasticizing effect than its stearic acid counterparts. The G′ values varied over a wide range with oil variation (749.40 Pa, fish oil to 39,570 Pa, flaxseed oil). The amount of unsaturation in oils was found to have a linear relationship with gel strength, as evident from the IR intensities of olefinic -C-H peaks. IR results also indicated the intactness of oil unsaturation and complete breakage of H-bonding upon gelation. The nature of oil greatly affected the thickness of polymer fibers in the oleogel, as evident from cryo-SEM results. © 2013 Elsevier Ltd. All rights reserved.
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 tak