Dalhousie University is a public research university in Nova Scotia, Canada, with three campuses in Halifax, and a fourth in Bible Hill. Dalhousie offers more than 4,000 courses and 180 degree programs in twelve undergraduate, graduate, and professional faculties. The university is a member of the U15, a group of research-intensive universities in Canada.Dalhousie was established as a nonsectarian college in 1818 by the Lieutenant Governor of Nova Scotia, George Ramsay, 9th Earl of Dalhousie, after whom the university was named. The college did not hold its first class until 1838, until then operating sporadically due to financial difficulties. It reopened for a third time in 1863 following a reorganization which brought a change of name to "The Governors of Dalhousie College and University". The university formally changed its name to "Dalhousie University" in 1997 through provincial legislation, the same legislation which had merged the institution with the Technical University of Nova Scotia.The Dalhousie library system currently operates the largest library in Atlantic Canada, as well as holds the largest collection of agricultural resource material in the region. The university operates a total of fourteen residences. There are currently two student unions that represent student interests at the university, the Dalhousie Student Union, and the Dalhousie Association for Graduate Students. Dalhousie's varsity teams, the Tigers, compete in the Atlantic University Sport conference of Canadian Interuniversity Sport. Dalhousie’s Faculty of Agriculture varsity teams are the Dalhousie Rams, and compete in the ACAA and CCAA.Dalhousie is a coeducational university with more than 18,000 students and over 110,000 alumni. Notable alumni include government officials, academics, business leaders and 89 Rhodes Scholars. The university ranked 244th in the 2013 QS World University Rankings, 251-275th in the 2012-2013 Times Higher Education World University Rankings, and 201–300th in the 2012 Academic Ranking of World Universities. Dalhousie is a centre for marine research, and is host to the headquarters of the Ocean Tracking Network. Wikipedia.
Dufton M.,Dalhousie University |
Franz-Odendaal T.A.,Mount Saint Vincent University
Developmental Dynamics | Year: 2015
Background: Understanding differences in tissue morphology has not been well researched, yet provides crucial insight into evolution. We investigate the effect of eye reduction on the shape of surrounding bones by examining two morphs of the Mexican tetra (Tinaja cavefish and sighted fish), F1 intermediates, zebrafish, a sighted tetra after lens removal and a zebrafish mutant, bum-/-, which has a degenerating lens. Results: Significantly, by comparing the skulls, we show that there are broadly similar effects on bone shape after eye reduction with bones posterior and dorsal to the eye consistently most affected in both species. We conclude that there are conserved mechanisms underlying bone shape changes in response to a reduced or lost eye. Of interest, when we compare the shapes of individual bones and the mode of eye reduction, differences suggest that the finer details of these underlying mechanisms may indeed vary. We also show that cavefish occupy a unique morphospace with respect to skull morphology and that F1 intermediates are most similar to sighted fish than their cavefish parent. Conclusions: This study highlights the dynamic nature of the vertebrate skull and its ability to respond to tissue changes within the head, a topic which has been largely overlooked in the literature. © 2015 Wiley Periodicals, Inc.
Hartmann K.,University of Tasmania |
Wong D.,Dalhousie University |
Stadler T.,Universitatsstrasse 16
Systematic Biology | Year: 2010
A wide range of evolutionary models for species-level (and higher) diversification have been developed. These models can be used to test evolutionary hypotheses and provide comparisons with phylogenetic trees constructed from real data. To carry out these tests and comparisons, it is often necessary to sample, or simulate, trees from the evolutionary models. Sampling trees from these models is more complicated than it may appear at first glance, necessitating careful consideration and mathematical rigor. Seemingly straightforward sampling methods may produce trees that have systematically biased shapes or branch lengths. This is particularly problematic as there is no simple method for determining whether the sampled trees are appropriate. In this paper, we show why a commonly used simple sampling approach (SSA)-simulating trees forward in time until n species are first reached-should only be applied to the simplest pure birth model, the Yule model. We provide an alternative general sampling approach (GSA) that can be applied to most other models. Furthermore, we introduce the constant-rate birth-death model sampling approach, which samples trees very efficiently from a widely used class of models. We explore the bias produced by SSA and identify situations in which this bias is particularly pronounced. We show that using SSA can lead to erroneous conclusions: When using the inappropriate SSA, the variance of a gradually evolving trait does not correlate with the age of the tree; when the correct GSA is used, the trait variance correlates with tree age. The algorithms presented here are available in the Perl Bio:Phylo package, as a stand-alone program TreeSample, and in the R TreeSim package. © The Author(s) 2010.
Adamo S.A.,Dalhousie University
BioScience | Year: 2013
Women and men enter graduate programs in biology in about equal numbers, but women are less likely to become academic scientists. Various hypotheses have been suggested to explain this higher rate of attrition, most of which cite family issues as the reason. However, medicine successfully recruits and retains women physicians, despite being less family friendly than biology in terms of workload, stress, and inflexible work hours. Both professions are competitive but at different times in a person's career. Competition for entry into medical school is intense, but this period of competition occurs prior to family formation for most women. For women biologists, the most intense period of competition occurs during the search for faculty positions. Many women have partners or children at this time. The increasing competition for academic positions threatens to reverse the gains that women have made into the professoriate in biology, as well as in other sciences. © 2013 by American Institute of Biological Sciences. All rights reserved.
Doolittle W.F.,Dalhousie University
Biology and Philosophy | Year: 2013
Our understanding of what microbes are and how they evolve has undergone many radical shifts since the late nineteenth century, when many still believed that bacteria could be spontaneously generated and most thought microbial "species" (if any) to be unstable and interchangeable in form and function (pleomorphic). By the late twentieth century, an ontology based on single cells and definable species with predictable properties, evolving like species of animals or plants, was widely accepted. Now, however, genomic and metagenomic data show that lateral gene transfer compromises this picture of stability and predictability, and refocuses our attention on multilineage communities. Treating such communities as unstable but identifiable evolving "individuals" makes us again pleomorphists, of a sort. © 2012 Springer Science+Business Media Dordrecht.
Susko E.,Dalhousie University
Biometrika | Year: 2013
When the null hypothesis constrains parameters to the boundary of the parameter space, the asymptotic null distribution of the likelihood ratio statistic is often a mixture of chi-squared distributions, giving rise to the so-called chi-bar test, where weights can depend on the true unknown parameter and be difficult to calculate. We consider the test that conditions on the observed number of null hypothesis parameters in the interior of the parameter space. This approach uses simple chi-squared thresholds, yields conservative asymptotic Type I error, and is guaranteed to give power improvements over the naive approach of simply ignoring boundary constraints. Simulations validate the theoretical results, illustrate application settings, and find power comparable with but usually less than that of the chi-bar test. © 2013 Biometrika Trust.
Andreas H.A.,Dalhousie University
Journal of the Electrochemical Society | Year: 2015
This perspective article outlines some of the key considerations and literature that have been published on self-discharge in electrochemical capacitors. While for some consumer applications self-discharge is not considered to be a significant issue (e.g. energy storage from regenerative breaking) in applications where the electrochemical capacitor is stored in the charged state for significant times (e.g. coupled with a battery in a cell phone), the impact on energy, power and recharging frequency of both the capacitor and battery can be significant. A description is provided here of the common methods of self-discharge study: half cell vs. full cell measurements and open-circuit potential decay versus float currents. A description of some of the models used to evaluate faradaic self-discharge is presented, with a synopsis of the important aspects of the many available charge redistribution models. An overview of the current self-discharge mechanisms for various ECs is provided, highlighting that for many systems there are significant factors of the self-discharge process which remain unknown. Finally, some future directions are anticipated for the field of self-discharge in electrochemical capacitors. © The Author(s) 2015. Published by ECS.
Duffy A.,Dalhousie University
British Journal of Psychiatry | Year: 2010
The contemporary model of mood disorders proposes that multiple susceptibility genes interact with multiple other risk factors. However, the specific nature of the genetic vulnerability and the intermediate causal pathways are not known. In this edition of the Journal, Goodyer and colleagues report new findings suggesting genetic moderation of an association between elevated cortisol and depression in high-risk adolescents.
Spiteri L.F.,Dalhousie University
Journal of Documentation | Year: 2012
Purpose: New social discovery systems have social-type Web 2.0 features that allow users to enhance the content of bibliographic records by adding their own tags, ratings, and reviews. One of the primary underlying principles of cataloguing is that catalogue records be designed with the user in mind, i.e. user convenience. The purpose of this paper is to explore the relationship between the principle of user convenience and social discovery systems. Design/methodology/approach: A review of the literature and codes of ethics of associations of information professions was undertaken to examine: the ethical dimensions of creating catalogue records to reflect user convenience, the relationship between culture and user convenience, and how social discovery tools can facilitate the creation of interactive and flexible catalogue records that reflect the culture(s) and needs of the library communities in which they exist. Findings: Social discovery systems can address the primary barriers to creating catalogue records that meet user convenience: determining and reflecting the needs and cultural warrant of the users, and maintaining the quality and integrity of the catalogue records. Practical implications: Social discovery systems can serve as a bridge between cataloguers' desire to create accurate catalogue records that conform to accepted cataloguing standards, and their ethical imperative to ensure that these records meet the needs of the clients. Originality/value: The findings of this study pave the way for further research into how user-contributed metadata allow clients to express their needs and cultural warrant and to interact with one another and library staff. © Emerald Group Publishing Limited.
Morsi W.G.,University of Ontario Institute of Technology |
El-Hawary M.E.,Dalhousie University
Electric Power Systems Research | Year: 2011
High power quality level is required in smart grids especially for non-stationary situations due to increased use of nonlinear loads and PQ disturbances such as dips, swells, transients and interruptions. Many power quality indices (PQIs) are available. In this paper a new fuzzy-wavelet packet transform-based power quality Index (FWPTPQI) is developed to amalgamate existing power quality indices as the output of a fuzzy based module based on fuzzy inference systems, knowledge base and existing PQI as input. Fuzzy systems allow handling the uncertainties associated with the electric power quality evaluation. The proposed approach has been applied to two case studies; stationary balanced and non-stationary unbalanced three-phase systems. The results are compatible with prevalent situations. The new index gives significant sense of the quality of transmitted electrical power. A comparative study of using different wavelet basis functions is considered and results indicate that Daubechies 10 and Daubechies 15 could be considered as the overall best wavelet basis functions. Since the new index represents an amalgamation of the PQ indices with less number of wavelet coefficients, it helps reduce the size of data processed which is required in smart grid applications. © 2011 Elsevier B.V. All rights reserved.
Morsi W.G.,University of Ontario Institute of Technology |
El-Hawary M.E.,Dalhousie University
Electric Power Systems Research | Year: 2011
Symmetrical components method allows systematic analysis of unbalanced three-phase systems. This method represents the backbone for many applications in an electric power system (EPS) such as fault analysis, power system protection, power and energy measurements. Moreover, with the increased penetration of plug-in hybrid electric vehicles (PHEVs), studying and evaluating the distribution system unbalance considering power quality disturbance pronounced by fleet of these vehicles, becomes a necessity. In time-invariant polluted environment, the measurements of the symmetrical components for the fundamental and harmonic components could be performed using Fourier basics. However Fourier-based techniques are unsuitable in the presence of any time-variant power quality disturbance which is typically the case when considering PHEVs and other nonlinear industrial process such as computer numerical control (CNC) machines. In this paper, time-frequency expressions for the symmetrical components are developed using different wavelet transforms: Discrete Wavelet Transform (DWT), Wavelet Packet Transform (WPT) and Stationary Wavelet Transform (SWT). The paper also includes a comparative study of the results obtained when applying the developed approach using different wavelet basis functions, such as Daubechies, Coiflets and Symlets into three case studies (two synthetic and one real) including unbalanced three-phase system under different operating conditions while considering different kind of disturbances. The results are analyzed and conclusions are presented. The outcomes of this study lay the ground for further studies in unbalanced distribution system with high penetration of PHEVs, two-way protection devices for smart grid and power quality evaluation. © 2011 Published by Elsevier B.V.
Capps B.,Dalhousie University
British Medical Bulletin | Year: 2016
Background Systematic reviews analysing the influence of funding on the conduct of research have shown how Conflicts of Interest (COIs) create bias in the production and dissemination of data. Sources of data The following is a critical analysis of current opinions in respect to COIs created by industry funding of medical research in academic institutions. Areas of agreement Effective mechanisms are necessary to manage COIs in medical research, and to prohibit COIs that clearly affect validity of research conduct and outcomes. Areas of controversy While most hold that industry investment in university research is not a barrier to good science, there are questions about how securing funding opportunities might be prioritized over the risks of potential COIs. It is argued that COIs are inherent risks to research integrity, requiring the strengthening of current governance frameworks. Growing points The focus on COIs, created by the ostensibly categorical actions of industry, challenges the evolving research priorities within academic institutions. Areas timely for developing research Less well-defined COIs are equally culpable to financial ones, in terms of the systemic damage they do to science. So, are they appropriately managed as risks within university research settings? © 2016 The Author 2016.
Ungar M.,Dalhousie University
Journal of Child Psychology and Psychiatry and Allied Disciplines | Year: 2015
Background: With growing interest in resilience among mental health care providers globally, there is a need for a simple way to consider the complex interactions that predict adaptive coping when there is exposure to high levels of adversity such as family violence, mental illness of a child or caregiver, natural disasters, social marginalization, or political conflict.Methods: This article presents diagnostic criteria for assessing childhood resilience in a way that is sensitive to the systemic factors that influence a child's wellbeing. The most important characteristics of children who cope well under adversity and avoid problems like depression, PTSD, and delinquency are highlighted.Results: A multidimensional assessment of resilience is presented that examines, first, the severity, chronicity, ecological level, children's attributions of causality, and cultural and contextual relevance of experiences of adversity. Second, promotive and protective factors related to resilience are assessed with sensitivity to the differential impact these have on outcomes depending on a child's level of exposure to adversity. These factors include individual qualities like temperament, personality, and cognitions, as well as contextual dimensions of positive functioning related to the available and accessibility of resources, their strategic use, positive reinforcement by a child's significant others, and the adaptive capacity of the environment itself. Third, an assessment of resilience includes temporal and cultural factors that increase or decrease the influence of protective factors. A decision tree for the diagnosis of resilience is presented, followed by a case study and diagnosis of a 15-year-old boy who required treatment for a number of mental health challenges.Conclusions: The diagnostic criteria for assessing resilience and its application to clinical practice demonstrate the potential usefulness of a systemic approach to understanding resilience among child populations. © 2014 Association for Child and Adolescent Mental Health.
Gero S.,Dalhousie University |
Gero S.,Andrews University
Proceedings. Biological sciences / The Royal Society | Year: 2013
It is hypothesized that the primary function of permanent social relationships among female sperm whales (Physeter macrocephalus) is to provide allomothers for calves at the surface while mothers make foraging dives. In order to investigate how reciprocity of allocare within units of sperm whales facilitates group living, we constructed weighted social networks based on yearly matrices of associations (2005-2010) and correlated them across years, through changes in age and social role, to study changes in social relationships within seven sperm whale units. Pairs of association matrices from sequential years showed a greater positive correlation than expected by chance, but as the time lag increased, the correlation coefficients decreased. Over all units considered, calves had high values for all measured network statistics, while mothers had intermediate values for most of the measures, but high values for connectedness and affinity. Mothers showed sharp drops in strength and connectedness in the first year of their new calves' lives. These broad patterns appear to be consistent across units. Calves appeared to be significant nodes in the network of the social unit, and thus provide quantitative support for the theory in which communal care acts as the evolutionary force behind group formation in this species.
Kirby J.,Dalhousie University
Journal of Medical Ethics | Year: 2010
Historically, the triage of temporarily scarce health resources has served narrow utilitarian ends. The recent H1N1 pandemic experience provided an opportunity for expanding the theoretical foundations/understandings of critical care triage in the context of declared infectious pandemics. This paper briefly explores the ethics-related challenges associated with the development of modern critical care triage protocols and provides descriptions of some 'enhanced fairness' features which were developed through the use of an inclusive deliberative engagement process by a Canadian provincial Department of Health.
Wideman J.G.,University of Exeter |
Munoz-Gomez S.A.,Dalhousie University
Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids | Year: 2016
The ER-mitochondria organizing network (ERMIONE) in Saccharomyces cerevisiae is involved in maintaining mitochondrial morphology and lipid homeostasis. ERMES and MICOS are two scaffolding complexes of ERMIONE that contribute to these processes. ERMES is ancient but has been lost in several lineages including animals, plants, and SAR (stramenopiles, alveolates and rhizaria). On the other hand, MICOS is ancient and has remained present in all organisms bearing mitochondrial cristae. The ERMIONE precursor evolved in the α-proteobacterial ancestor of mitochondria which had the central subunit of MICOS, Mic60. The subsequent evolution of ERMIONE and its interactors in eukaryotes reflects the integrative co-evolution of mitochondria and their hosts and the adaptive paths that some lineages have followed in their specialization to certain environments. By approaching the ERMIONE from a perspective of comparative evolutionary cell biology, we hope to shed light on not only its evolutionary history, but also how ERMIONE components may function in organisms other than S. cerevisiae. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon. © 2016 Elsevier B.V.
Khakzad N.,Memorial University of Newfoundland |
Khan F.,Memorial University of Newfoundland |
Amyotte P.,Dalhousie University
Safety Science | Year: 2013
Blowouts are among the most undesired and feared accidents during drilling operations. The dynamic nature of blowout accidents, resulting from both rapidly changing physical parameters and time-dependent failure of barriers, necessitates techniques capable of considering time dependencies and changes during the lifetime of a well. The present work is aimed at demonstrating the application of bow-tie and Bayesian network methods in conducting quantitative risk analysis of drilling operations. Considering the former method, fault trees and an event tree are developed for potential accident scenarios, and then combined to build a bow-tie model. In the latter method, first, individual Bayesian networks are developed for the accident scenarios and finally, an object-oriented Bayesian network is constructed by connecting these individual networks. The Bayesian network method provides greater value than the bow-tie model since it can consider common cause failures and conditional dependencies along with performing probability updating and sequential learning using accident precursors. © 2013 Elsevier Ltd.
Cohen M.M.,Dalhousie University
American Journal of Medical Genetics, Part A | Year: 2013
RAGE stands for Receptor of Advanced Glycation Endproducts. The two main topics discussed are (1) the nature of RAGE signaling and (2) its role in cardiovascular disease. RAGE may occur in membrane-bound form or in secretory form. RAGE signaling involves multiple ligands: (1) several AGEs (2) amyloid β pecursor protein (APP), (3) high mobility group box 1 (HMGB1), (4) S100A4, (5) S100A8/A9, and (6) S100A12, which are calcium-binding proteins, and (7) S100B, a glial-derived protein. RAGE ligands and various diseases involving RAGE signaling are summarized in tabular form. © 2013 Wiley Periodicals, Inc.
Dunbar M.J.,Dalhousie University
The bone & joint journal | Year: 2013
Satisfaction is increasingly employed as an outcome measure for a successful total knee replacement (TKR). Satisfaction as an outcome measure encompasses many different intrinsic and extrinsic factors related to a person's experience before and after TKR. The Swedish Knee Arthroplasty Registry has previously demonstrated on a large population study that 17% of TKR recipients are not satisfied with their TKR outcome. This finding has been replicated in other countries. Similar significant factors emerged from these registry studies that are related to satisfaction. It would appear that satisfaction is better after more chronic diseases and whether the TKR results in pain relief or improved function. Importantly, unmet pre-operative expectations are a significant predictor for dissatisfaction following a TKR. It may be possible to improve rates by addressing the issues surrounding pain, function and expectation before embarking on surgery.
Gebel H.M.,Emory University |
Liwski R.S.,Dalhousie University |
Bray R.A.,Emory University
Current Opinion in Organ Transplantation | Year: 2013
Purpose of Review: Since the landmark studies of Patel and Terasaki, pretransplant identification of donor-directed HLA alloantibodies (DSAs) has been a critical prelude to renal allograft transplantation. Pretransplant, DSAs may be an acceptable risk or an unconditional contraindication to transplantation depending on the particular donorâ€Š: â€Šrecipient combination. Posttransplant, DSAs are associated with episodes of acute rejection, chronic rejection, and graft loss. Thus, monitoring for such antibodies is an important aspect of patient care. Recent Findings: The development of solid-phase antibody detection assays significantly enhanced our ability to identify HLA antibodies, taking virtual crossmatching from concept to reality. At the root of these detection assays are two questions that have been asked for almost 50 years: are donor-directed HLA antibodies present and, if so, are they clinically relevant? While the technology related to solid-phase antibody detection has seemingly allowed the first question to be answered with exquisite sensitivity and specificity, can the same be said for question 2? Summary: Solid-phase antibody detection assays have clear benefits over historical approaches to antibody identification, but are not flawless. In fact, the limitations of these assays are frequently ignored. Herein, the strengths and weaknesses of solid-phase antibody detection are highlighted. © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins.
Martin D.H.,Dalhousie University
International Journal of Circumpolar Health | Year: 2011
Objectives. Culture, history and social circumstances shape how people understand their relationships to food, what foods are eaten, when, how much and how often. This ultimately shapes overall health. This study aims to connect research about food, culture and health by positioning south-eastern Labrador Inuit understandings of food at the forefront of how we begin to address chronic disease within southeastern Labrador Inuit communities. Study design. This study collected stories about food from 3 generations of men and women who live in the south-east Labrador Inuit community of St. Lewis, Newfoundland and Labrador. Methods. Qualitative interviews (n=24) and 1 focus group (n=8) were conducted with 3 generations of men and women who were asked to share stories about how they experience and understand their relationships to food. Results. Local plants and animals have historically been used for shelter, clothing and medicines, and their procurement provided opportunities for physical activity, sharing with others and passing along generational knowledge. The historical absence of government services has meant that stable food supplies were unavailable; local sources of food have, until the recent past, been essential for survival. The significant change over a short period, from having to ensure that one has enough to eat and avoiding nutritional deficiencies, to having both healthy and unhealthy food choices constantly available, has required a different "way" of understanding food. Conclusions. It is imperative that nutrition programs and resources directed towards improving the health of south-east Labrador Inuit take into account how cultural, historical and social circumstances have shaped south-east Labrador Inuit understandings of food.
Coll M.,Dalhousie University |
Coll M.,CSIC - Institute of Marine Sciences |
Libralato S.,National Institute of Oceanography and Applied Geophysics - OGS
Fish and Fisheries | Year: 2012
Ecological modelling tools are applied worldwide to support the ecosystem-based approach of marine resources (EAM). In the last decades, numerous applications were attempted in the Mediterranean Sea, mainly using the Ecopath with Ecosim (EwE) tool. These models were used to analyse a variety of complex environmental problems. Many applications analysed the ecosystem impacts of fishing and assessed management options. Other studies dealt with the accumulation of pollution through the food web, the impact of aquaculture or the ecosystem effects of climate change. They contributed to the scientific aspects of an ecosystem-based approach in the region because they integrated human activities within an ecosystem context and evaluated their impact on the marine food web, including environmental factors. These studies also gathered a significant amount of information at an ecosystem level. Thus, in the second part of this review, we used this information to quantify structural and functional traits of Mediterranean marine ecosystems at regional scales as the illustration of further potentialities of EwE for an EAM. Results highlighted differential traits between ecosystem types and a few between basins, which illustrate the environmental heterogeneity of the Mediterranean Sea. Moreover, our analysis evidenced the importance of top predators and small pelagic fish in Mediterranean ecosystems, in addition to the structural role of benthos and plankton organisms. The impact of fishing was high and of a similar intensity in the western, central and eastern regions and showed differences between ecosystem types. The keystone role of species was more prominent in protected environments. © 2011 Blackwell Publishing Ltd.
Huismans R.S.,University of Bergen |
Beaumont C.,Dalhousie University
Earth and Planetary Science Letters | Year: 2014
Even though many basic properties of non-volcanic rifted margins are predicted by uniform extension of the lithosphere, uniform extension fails to explain other important characteristics. Particularly significant discrepancies are observed at: 1) the Iberia-Newfoundland conjugate margins (Type I), where large tracts of continental mantle lithosphere are exposed at the seafloor, and at 2) ultra-wide central South Atlantic margins (Type II) where continental crust spans wide regions below which it appears that lower crust and mantle lithosphere were removed. Neither corresponds to uniform extension in which crust and mantle thin by the same factor. Instead, either the crust or mantle lithosphere has been preferentially removed during extension. We show that the Type I and II styles are respectively reproduced by dynamical numerical lithospheric stretching models (Models I-A/C and II-A/C) that undergo depth-dependent extension. In this notation A and C imply underplating of the rift zone during rifting by asthenosphere and lower cratonic lithosphere, respectively. We also present results for models with a weak upper crust and strong lower crust, Models III-A/C, to show that lower crust can also be removed from beneath the rift zone by horizontal advection with the mantle lithosphere. From the model results we infer that these Type I, II, and III margin styles are controlled by the strength of the mid/lower crust, which determines the amount of decoupling between upper and lower lithosphere during extension and the excision of crust or mantle. We also predict the styles of sedimentary basins that form on these margins as a test of the concepts presented. © 2014 Elsevier B.V.
Oliver E.C.J.,University of Tasmania |
Oliver E.C.J.,Dalhousie University
Theoretical and Applied Climatology | Year: 2015
The Madden–Julian Oscillation (MJO), the dominant mode of intraseasonal variability in the tropics, is known to influence extratropical air temperature in the Northern Hemisphere. In particular, it has been shown that intraseasonal variations in wintertime Alaska surface air temperature (SAT) is linked with variations in cross-shore surface wind and that this mechanism is driven by a train of Rossby waves originating in the tropics due to MJO forcing. We show, using long station records of Alaska SAT and an independent reconstruction of the MJO index over the twentieth century, that the MJO–SAT connection in Alaska has undergone significant multidecadal variability over the last century. The Pacific Decadal Oscillation appears to explain some of the observed multidecadal variability but fails to capture a large proportion of it. We identify four distinct periods between the years 1910 and 2000 that exhibit either a weak, moderate or strong MJO–SAT connection. The nature of our method ensures that the detected multidecadal variability is due to changes in the teleconnection mechanism and not due to changes in the strength of the MJO index. Finally, we speculate on the mechanism which may bring about such multidecadal variations in the teleconnection mechanism. © 2014, Springer-Verlag Wien.
Mitchell D.E.,Dalhousie University
Clinical and Experimental Optometry | Year: 2013
Extended periods of complete darkness have long been used among other early experiential manipulations to explore the role of visual experience in the development of the visual pathways. In the last decade, short periods of darkness have been used to facilitate the imposition of different or conflicting visual input each day to explore the manner by which processes of perinatal development controlled by gene action are refined subsequently by visual experience. Very recently, periods of complete darkness of intermediate length (10 days) have been shown to promote very fast recovery from amblyopia induced by prior monocular deprivation (MD). When imposed immediately after a period of MD, in certain circumstances, darkness appears to insulate against the development of amblyopia. It is proposed that complete darkness may reverse maturation of many of the so-called braking molecules in the visual cortex, so that it reverts to a more juvenile state. Clinical and Experimental Optometry. © 2012 The Author Clinical and Experimental Optometry © 2012 Optometrists Association Australia.
Lees C.,Dalhousie University |
Hopkins J.,McMaster University
Preventing Chronic Disease | Year: 2013
Introduction Although the effects of aerobic physical activity (APA) on children's physical health is well characterized, the effect of aerobic physical activity on cognition, academic achievement, and psychosocial function has not yet been established. This systematic review provides an overview of research elucidating the relationship between aerobic physical activity and children's cognition, academic achievement, and psychosocial function. Methods A systematic review of English articles was performed in April 2013 using MEDLINE, Cochrane, PsycINFO, SPORTDiscus, and EMBASE. Additional studies were identified through back-searching bibliographies. Only randomized control trials with an intervention of aerobic physical activity in children younger than 19 years that measured psychological, behavioral, cognitive, or academic outcomes were included. Results We found 8 relevant randomized control trials that met our inclusion criteria and extracted relevant data and evaluated the methodologic quality of the studies. Of the 8 studies identified, 2 studies were crossover randomized control trials studying the effects of acute aerobic physical activity on cognitive performance. Six studies were parallel-group randomized control studies, of which only 2 had a follow-up period of longer than 6 months. All studies showed that APA had a generally positive impact on children's cognition and psychosocial function. However, this relationship was found to be minimal in many studies and in some measures, no significant improvement was seen at all. There was no documentation of APA having any negative impact on children's cognition and psychosocial health, even in cases where school curriculum time was reassigned from classroom teaching to aerobic physical activity. Conclusion APA is positively associated with cognition, academic achievement, behavior, and psychosocial functioning outcomes. More rigorous trials with adequate sample sizes assessing the impact of APA on children's cognitive abilities, psychosocial functioning, behavior, and academic achievement are needed, with standardized interventions, valid and reliable tools of measurement, and long-term follow-up for sustained cognitive and psychosocial outcomes.
File Jr. T.M.,Ohio University |
Marrie T.J.,Dalhousie University
Postgraduate Medicine | Year: 2010
To determine the burden of community-acquired pneumonia (CAP) affecting adults in North America, a comprehensive literature review was conducted to examine the incidence, morbidity and mortality, etiology, antibiotic resistance, and economic impact of CAP in this population. In the United States, there were approximately 4.2 million ambulatory care visits for pneumonia in 2006. Pneumonia and infl uenza continue to be a common cause of death in the United States (ranked eighth) and Canada (ranked seventh). In 2005, there were > 60 000 deaths due to pneumonia in persons aged ≥ 15 years in the United States alone. The hospitalization rate for all infectious diseases increased from 1525 hospitalizations per 100 000 persons in 1998 to 1667 per 100 000 persons in 2005. Admission to an intensive care unit was required in 10% to 20% of patients hospitalized with pneumonia. The mean length of stay for pneumonia was ≥ 5 days and the 30-day rehospitalization rate was as high as 20%. Mortality was highest for CAP patients who were hospitalized; the 30-day mortality rate was as high as 23%. All-cause mortality for CAP patients was as high as 28% within 1 year. Streptococcus pneumoniae continues to be the most frequently identifi ed pathogen associated with CAP, and pneumococcal resistance to antimicrobials may make treatment more diffi cult. The economic burden associated with CAP remains substantial at > $17 billion annually in the United States. Despite the availability and widespread adherence to recommended treatment guidelines, CAP continues to present a signifi cant burden in adults. Furthermore, given the aging population in North America, clinicians can expect to encounter an increasing number of adult patients with CAP. Given the signifi cance of the disease burden, the potential benefi t of pneumococcal vaccination in adults is substantial. © Postgraduate Medicine.
File T.M.,Northeast Ohio Medical University |
Marrie T.J.,Dalhousie University
Infectious Disease Clinics of North America | Year: 2013
The present controversy regarding the need to cover atypical pathogens in the empiric therapy of community-acquired pneumonia is related to several issues, including the relevance of terminology, imprecise diagnostic methods, and perceived contradictory results of published evidence. Studies evaluating the time to clinical recovery and the use of earlier endpoints for evaluation suggest that appropriate therapy provides a benefit if an atypical pathogen is a pathogen. Because recent surveillance studies suggest these pathogens are common and until there is the availability of accurate, cost-effective, and easily interpreted laboratory tests to provide the etiologic diagnosis at the time of point of care, empiric therapy of atypical pathogens is supported. © 2013 Elsevier Inc.
Ponomarenko S.A.,Dalhousie University
Optics Express | Year: 2011
We develop a general representation for ensembles of non-stationary random pulses in terms of statistically uncorrelated, timedelayed, frequency-shifted Gaussian pulses which are classical counterparts of coherent states of a quantum harmonic oscillator. We show that the two-time correlation function describing second-order statistics of the pulses can be expanded in terms of the complex Gaussian pulses. We also demonstrate how the novel formalism can be applied to describe recently introduced Gaussian Schell-model pulses and pulse trains generated by typical mode-locked lasers. © 2011 Optical Society of America.
Gray M.W.,Dalhousie University
Cold Spring Harbor Perspectives in Biology | Year: 2014
Mitochondrial DNA (mtDNA) is unquestionably the remnant of an a-proteobacterial genome, yet only 10%-20% of mitochondrial proteins are demonstrably a-proteobacterial in origin (the "a-proteobacterial component," or APC). The evolutionary ancestry of the nona- proteobacterial component (NPC) is obscure and not adequately accounted for in current models of mitochondrial origin. I propose that in the host cell that accommodated an aproteobacterial endosymbiont, much of the NPC was already present, in the form of a membrane-bound metabolic organelle (the premitochondrion) that compartmentalized many of the non-energy-generating functions of the contemporary mitochondrion. I suggest that this organelle also possessed a protein import system and various ion and small-molecule transporters. In such a scenario, an a-proteobacterial endosymbiont could have been converted relatively directly and rapidly into an energy-generating organelle that incorporated the extant metabolic functions of the premitochondrion. This model (the "preendosymbiont hypothesis") effectively represents a synthesis of previous, contending mitochondrial origin hypotheses, with the bulk of the mitochondrial proteome (much of the NPC) having an endogenous origin and the minority component (the APC) having a xenogenous origin. © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.
Wasel B.A.,Dalhousie University
BMJ case reports | Year: 2013
Malignant serous cystic neoplasms (SCN) of the pancreas are exceptionally rare, and only a few cases have been reported. As a result, SCN have been unanimously classified as benign tumours. Contrary to this conviction, in 1989, George et al published the very first case of a patient found to have a malignant pancreatic SCN. Up to the time of the submission of this paper, 27 cases of serous cystoadenocarcinomas have been published. In all the previously published cases of malignant SCN, the correct diagnosis was made postoperatively or at the time of autopsy. The authors present a case of a 68-year-old patient who was incidentally found to have a large liver mass on transthoracic echocardiogram ordered for suspected coronary artery insufficiency. Subsequent investigations revealed an additional large mass in the pancreas and percutaneous biopsies of both lesions revealed histological features consistent with malignant SCN metastasised to the left hepatic lobe.
Weaver D.F.,Dalhousie University
Epilepsia | Year: 2013
Pharmacoresistant epilepsy is a significant medical problem. The 2nd Halifax International Epilepsy Conference & Retreat identified crucial needs, which if successfully addressed, will aid in paving the way to improved lives for people with pharmacoresistant epilepsy. These are needs: (1) for an evidence-based and dynamic definition of pharmacoresistant epilepsy; (2) for a comprehensive description of the natural history of pharmacoresistant epilepsy; (3) for a comprehensive description of the complications and comorbidities of pharmacoresistant epilepsy; (4) for a rigorous delineation of the epidemiology and socioeconomic impact of pharmacoresistant epilepsy; (5) for clinically meaningful diagnostic and prognostic physiologically based electroencephalography (EEG) biomarkers; (6) for clinically meaningful diagnostic and prognostic anatomically based (MRI Imaging) biomarkers; (7) for biomolecular/biochemical mechanistic understanding of etiopathogenesis for pharmacoresistant epilepsy; (8) for representative animal models of pharmacoresistant epilepsy; (9) for new and effective drugs or other novel treatments for pharmacoresistant epilepsy; and (10) to promote continuing research and research funding targeting pharmacoresistant epilepsy. Wiley Periodicals, Inc. © 2013 International League Against Epilepsy.
Feindel K.W.,Dalhousie University
Epilepsia | Year: 2013
Recent improvements in magnetic resonance imaging (MRI) hardware, software, and analysis routines are helping to put cases of "MR-negative" epilepsy on the decline. However, most standard-of-care MRI relies on careful manipulation and presentation of T1, T2, and diffusion-weighted contrast, which characterize the behavior of water in "bulk" tissue rather than providing pathology-specific contrast. Research efforts in MR physics continue to identify and develop novel theory, and methods such as diffusional kurtosis imaging (DKI) and temporal diffusion spectroscopy that can better characterize tissue substructure, and chemical exchange saturation transfer (CEST) that can target underlying biochemical processes. The potential role of each technique in targeting pathologies implicated in "MR-negative" epilepsy is outlined herein. Wiley Periodicals, Inc. © 2013 International League Against Epilepsy.
Teweldeberhan A.M.,Lawrence Livermore National Laboratory |
Dubois J.L.,Lawrence Livermore National Laboratory |
Bonev S.A.,Lawrence Livermore National Laboratory |
Bonev S.A.,Dalhousie University
Physical Review Letters | Year: 2010
The phase diagram of Ca is examined using a combination of density-functional theory (DFT) and diffusion quantum Monte Carlo (DMC) calculations. Gibbs free energies of several competing structures are computed at pressures near 50 GPa. Existing disagreements for the stability of Ca both at low and room temperature are resolved with input from DMC. Furthermore, DMC calculations are performed on 0 K crystalline structures up to 150 GPa and it is demonstrated that the widely used generalized gradient approximation of DFT is insufficient to accurately account for the relative stability of the high-pressure phases of Ca. The results indicate that the theoretical phase diagram of Ca needs a revision. © 2010 The American Physical Society.
Colohan S.M.,Dalhousie University |
Colohan S.M.,London School of Hygiene and Tropical Medicine
Journal of Burn Care and Research | Year: 2010
Burn injuries are a significant problem with high associated morbidity and mortality. Those associated with inhalational trauma (IHT) may be associated with higher mortality, but studies on prognosis are small and underpowered. This study was designed to identify prognostic factors that increase the risk of death, to quantify this risk, and to identify existing prognostic models. An electronic search of English-language publications that identify prognostic risk factors in thermal burns including IHT was carried out. Each article was reviewed systematically, and data extraction, quality assessment, and summarization of the articles were performed. Thirteen articles that met the inclusion/exclusion criteria of this study were reviewed. Overall, the mortality rate among burn patients in this review was 13.9% (4-28.3%), with the mortality rate among those with IHT being 27.6% (7.8-28.3%). Those studies with multivariate analyses identified increasing %TBSA, presence of IHT, and increasing age as the strongest predictors for mortality in this patient population. It seems that %TBSA, presence of IHT, and age are the best predictors of mortality among the current published literature on burn prognosis. © 2010 by the American Burn Association.
Lauzon-Guay J.-S.,Maurice Lamontagne Institute |
Scheibling R.E.,Dalhousie University
Marine Ecology Progress Series | Year: 2010
On the Atlantic coast of Nova Scotia, transitions between alternative states of the subtidal ecosystem, kelp beds and sea urchin barrens, occur on a decadal scale. To explore the process of urchin aggregation within kelp beds that leads to the shift to barrens, we developed a coupled map lattice model to simulate the spatial dynamics of kelp and green sea urchin Strongylocentrotus droebachiensis abundance over time. Our simulations show that the following factors can cause sea urchins to form grazing aggregations that create gaps in a kelp bed: (1) random movement by >60% of sea urchins residing in the bed, (2) moderate to high levels of spatial variability in sea urchin recruitment (30 to 90 [urchins m-2]2), (3) localized aggregation of sea urchins (150 urchins m-2) amid a moderate to high background density of sea urchins within the kelp bed (>10 urchins m-2), with or without a chemotactic response of sea urchins to kelp, and (4) removal of kelp from areas >20 m2 (to simulate physical or biological disturbance, or harvesting). Gaps formed at random locations within the spatial domain and expanded and coalesced to form barrens in which sea urchins were randomly distributed. Sea urchins formed circular fronts around gaps in the kelp bed. The rate of advance of fronts (and increase in gap size) was linearly related to the density of sea urchins at the front. The duration of the transition to the barrens state decreased with increases in (1) the proportion (Pm) of sea urchins moving (from >6 yr for Pm = 0.8 to <2 yr for P m = 1) and (2) the variance of sea urchin recruitment (from >5 yr for 30 [urchins m-2]2 to >3 yr for 90 [urchins m -2]2). Our findings support observations of gap formation within kelp beds that resulted in widespread destructive grazing on this coast in the late 1960s. Our model provides a predictive tool for the design of monitoring programs and field experiments to explore the underlying mechanisms of an ecosystem phase shift that has major ecological consequences. © Inter-Research 2010.
George R.B.,Dalhousie University |
Allen T.K.,Duke University |
Habib A.S.,Duke University
Anesthesia and Analgesia | Year: 2013
BACKGROUND:: The current standard labor epidural analgesic regimens consist of a local anesthetic in combination with an opioid delivered via continuous epidural infusion (CEI). With CEI local anesthetic, doses may be large with resulting profound motor blockade potentially affecting the incidence of instrumental deliveries. In this systematic review of randomized controlled trials (RCTs), we compared the effect of intermittent epidural bolus (IEB) to standard CEI dosing with or without patient-controlled epidural analgesia on patient satisfaction, the need for manual anesthesia interventions, labor progression, and mode of delivery in healthy women receiving labor epidural analgesia. METHODS:: A systematic review of RCTs that compared CEI with IEB for labor analgesia was performed. The articles were evaluated for validity, and data were extracted by the authors and summarized using odds ratios (ORs), mean differences (MDs), and 95% confidence intervals (CIs). RESULTS:: Nine RCTs were included in this systematic review. Three hundred forty-four subjects received CEI, whereas 350 subjects received IEB labor analgesia. All 9 studies were deemed to be low risk of bias. There was no statistical difference detected between IEB and CEI in the rate of cesarean delivery (OR, 0.87; 95% CI, 0.56-1.35), duration of labor (MD, -17 minutes; 95% CI, -42 to 7), or the need for anesthetic intervention (OR, 0.56; 95% CI, 0.29-1.06). IEB did result in a small but statistically significant reduction in local anesthetic usage (MD, -1.2 mg bupivacaine equivalent per hour; 95% CI, -2.2 to -0.3). Maternal satisfaction score (100-mm visual analog scale) was higher with IEB (MD, 7.0 mm; 95% CI, 6.2-7.8). CONCLUSIONS:: IEB is an appealing concept; current evidence suggests IEB slightly reduces local anesthetic usage and improves maternal satisfaction. Given the wide CIs of the pooled results for many outcomes, definite conclusions cannot be drawn for those outcomes, but there is also a potential that IEB improves instrumental delivery rate and need of anesthesia interventions. More study is required to conceptualize the ideal IEB regimen and investigate its effect on labor analgesia and obstetric outcomes. Copyright © 2012 International Anesthesia Research Society.
Coughlin J.E.,University of California at Santa Barbara |
Henson Z.B.,University of California at Santa Barbara |
Welch G.C.,Dalhousie University |
Bazan G.C.,University of California at Santa Barbara
Accounts of Chemical Research | Year: 2014
Organic semiconductors incorporated into solar cells using a bulk heterojunction (BHJ) construction show promise as a cleaner answer to increasing energy needs throughout the world. Organic solar cells based on the BHJ architecture have steadily increased in their device performance over the past two decades, with power conversion efficiencies reaching 10%. Much of this success has come with conjugated polymer/fullerene combinations, where optimized polymer design strategies, synthetic protocols, device fabrication procedures, and characterization methods have provided significant advancements in the technology. More recently, chemists have been paying particular attention to well-defined molecular donor systems due to their ease of functionalization, amenability to standard organic purification and characterization methods, and reduced batch-to-batch variability compared to polymer counterparts.There are several critical properties for efficient small molecule donors. First, broad optical absorption needs to extend towards the near-IR region to achieve spectral overlap with the solar spectrum. Second, the low lying highest occupied molecular orbital (HOMO) energy levels need to be between -5.2 and -5.5 eV to ensure acceptable device open circuit voltages. Third, the structures need to be relatively planar to ensure close intermolecular contacts and high charge carrier mobilities. And last, the small molecule donors need to be sufficiently soluble in organic solvents (≥10 mg/mL) to facilitate solution deposition of thin films of appropriate uniformity and thickness. Ideally, these molecules should be constructed from cost-effective, sustainable building blocks using established, high yielding reactions in as few steps as possible. The structures should also be easy to functionalize to maximize tunability for desired properties.In this Account, we present a chronological description of our thought process and design strategies used in the development of highly efficient molecular donors that achieve power conversion efficiencies greater than 7%. The molecules are based on a modular D1-A-D 2-A-D1 architecture, where A is an asymmetric electron deficient heterocycle, which allowed us to quickly access a library of compounds and develop structure-property-performance relationships. Modifications to the D1 and D2 units enable spectral coverage throughout the entire visible region and control of HOMO energy levels, while adjustments to the pendant alkyl substituents dictate molecular solubility, thermal transition temperatures, and solid-state organizational tendencies. Additionally, we discuss regiochemical considerations that highlight how individual atom placements can significantly influence molecular and subsequently device characteristics.Our results demonstrate the utility of this architecture for generating promising materials to be integrated into organic photovoltaic devices, call attention to areas for improvement, and provide guiding principles to sustain the steady increases necessary to move this technology forward. © 2013 American Chemical Society.
Langley R.G.,Dalhousie University |
Reich K.,Dermatologikum Hamburg
British Journal of Dermatology | Year: 2013
Psoriasis is a chronic disease requiring long-term therapy, which makes finding treatments with favourable long-term safety and efficacy profiles crucial. The goal of this review is to provide the background needed to evaluate properly long-term studies of biologic treatments for psoriasis. Firstly, important elements of design and analysis strategies are described. Secondly, data from published trials of biologic therapies for psoriasis are reviewed in light of the design and analysis choices implemented in the studies. Published reports of clinical trials of biologic treatments (adalimumab, alefacept, etanercept, infliximab or ustekinumab) that lasted 33 weeks or longer and included efficacy results and statistical analysis were reviewed. Study designs and statistical analyses were evaluated and summarized, emphasizing patient follow-up methods and handling of missing data. Various trial designs and data handling methods are used in long-term studies of biologic psoriasis treatments. Responder analyses in long-term trials can be conducted in responder enrichment, re-treated nonresponder or intent-to-treat trials. Missing data can be handled in four ways, including, from most to least conservative, nonresponder imputation, last-observation-carried-forward, as-observed analysis and anytime analysis. Long-term clinical trials have shown that adalimumab, alefacept, etanercept, infliximab and ustekinumab are efficacious for psoriasis treatment; however, without common standards for these trials, direct comparisons of these agents are difficult. Understanding differences in trial design and data handling is essential to make informed treatment decisions. What's already known about this topic? The chronic nature of psoriasis makes long-term efficacy studies particularly valuable for making treatment decisions. Complicated trial designs and inconsistent data handling methods make direct comparisons between trials difficult. What does this study add? A thorough explanation of trial types and data handling variations is provided, allowing readers to analyse effectively efficacy data reports. Currently available clinical trial results of biologic psoriasis treatment agents are reviewed and evaluated. © 2013 British Association of Dermatologists.
Dar R.,Tel Aviv University |
Barrett S.P.,Dalhousie University
Journal of Psychopharmacology | Year: 2014
The placebo effect of a psychoactive drug can be defined as the effect of expecting the drug in the absence of its pharmacological actions. As nicotine is widely believed to be the primary factor driving cigarette smoking, smokers are likely to expect nicotine to alleviate craving and withdrawal. The present review examines the extent to which any observed effects of nicotine, and especially its craving- and withdrawal-reducing effects, can be attributed to placebo. We begin by reviewing studies that examined the placebo effects of nicotine in the laboratory and follow with a review of potential placebo effects that are typically not controlled in placebo-controlled studies of nicotine replacement therapy (NRT). In laboratory studies, nicotine instructions decrease tobacco smoking, craving and/or withdrawal, while nicotine-specific effects have not been consistently reported. In field trials of NRT, there is a general failure to assess smokers' beliefs regarding their drug assignment. This omission makes it difficult to unequivocally attribute findings of placebo-controlled NRT studies to the physiological effects of nicotine. In sum, our review indicates that the placebo effects of nicotine, and specifically nicotine content expectations, may account for many of the benefits associated with nicotine delivery devices in both laboratory and field studies. © The Author(s) 2014.
Ghasemi A.,Dalhousie University |
Hodkiewicz M.R.,University of Western Australia
IEEE Transactions on Reliability | Year: 2012
This paper develops a prognostics model to estimate the Mean Residual Life of Rail Wagon Bearings within certain confidence intervals. The prognostics model is constructed using a Proportional Hazards approach, informed by imperfect data from a bearing acoustic monitoring system, and a failure database. The model supports prediction within a defined maintenance planning window from the time of receipt of the latest acoustic condition monitoring information. We use the model to decide whether to replace a bearing, or leave it until collection of the next condition monitoring indicators. The model is tested on a limited number of cases, and demonstrates good predictive capability. Opportunities to improve the performance of the model are identified, and the processes necessary and time required to build the model are described. Lessons learned from dealing with real field data will assist those interested in using prognostics to support maintenance planning activities. © 1963-2012 IEEE.
Khakzad N.,Memorial University of Newfoundland |
Khan F.,Memorial University of Newfoundland |
Amyotte P.,Dalhousie University
Reliability Engineering and System Safety | Year: 2012
Accident probability estimation is a common and central step to all quantitative risk assessment methods. Among many techniques available, bow-tie model (BT) is very popular because it represent the accident scenario altogether including causes and consequences. However, it suffers a static structure limiting its application in real-time monitoring and probability updating which are key factors in dynamic risk analysis. The present work is focused on using BT approach in a dynamic environment in which the occurrence probability of accident consequences changes. In this method, on one hand, failure probability of primary events of BT, leading to the top event, are developed using physical reliability models, and constantly revised as physical parameters (e.g., pressure, velocity, dimension, etc) change. And, on the other hand, the failure probability of safety barriers of the BT are periodically updated using Bayes' theorem as new information becomes available over time. Finally, the resulting, updated BT is used to estimate the posterior probability of the consequences which in turn results in an updated risk profile. © 2012 Elsevier Ltd. All rights reserved.
Fierlbeck K.,Dalhousie University
Social Science and Medicine | Year: 2014
For over a decade, beginning in the late 1990s, discussion over softer modes of governance animated academic scholarship in the fields of law, politics, and public policy. This debate was especially pronounced in Europe. Since the late 2000s, however, discussion of this approach has declined precipitously. Is the "soft governance" model dead? Or, more precisely, has the economic crisis killed it? This article argues that, to the contrary, the EU's austerity measures have made softer governance more relevant in two quite distinct ways. Administratively, new mechanisms of health policy coordination are able to provide policy solutions in a much more effective way than could more formal and rigid forms of legal harmonisation. Politically, it establishes a normative perspective which unifies actors across a number of administrative units and challenges the dominant ideological force of the market-based principles upon which the EU's austerity policies are constructed. © 2014.
Selinger P.,Dalhousie University
Electronic Notes in Theoretical Computer Science | Year: 2011
We show that an equation follows from the axioms of dagger compact closed categories if and only if it holds in finite dimensional Hilbert spaces. © 2011 Elsevier B.V. All rights reserved.
Ungar M.,Dalhousie University
Journal of Family Psychotherapy | Year: 2010
A convergence of epistemological innovations occurring in fields as diverse as sociology, ecology, and the cross-cultural study of psychology makes it difficult to assert what is and is not a benchmark of positive development under stress. Although these innovations complicate the study of resilience, understanding developmental outcomes of individuals and families as variable across cultures and contexts helps to broaden how we conceptualize protective processes. In this article, I use examples from family therapy and research to explore these areas of innovation. A definition of resilience based on these innovations explains how positive outcomes are the result of navigation to health resources and negotiation for resources to be provided in meaningful ways. Four implications for practice are discussed.
Zhaxybayeva O.,West Virginia University |
Doolittle W.F.,Dalhousie University
Current Biology | Year: 2011
The four disparate images shown in Figure 1 have this in common: each represents a radical adaptation that would not have happened had lateral gene transfer (LGT), also known as horizontal gene transfer (HGT), not been the powerful evolutionary force we now know it to be. Those who study the phenomenon are still struggling to quantitatively assess LGT as a process or processes and accommodate its implications for how patterns in nature should be represented - such as the existence of definable species or a meaningful universal Tree of Life. But all agree that the exchange of genetic information across species lines - which is how we will define LGT in this primer - is far more pervasive and more radical in its consequences than we could have guessed just a decade ago. Both prokaryotes (bacteria and archaea) and eukaryotes have experienced LGT, though its potential as a source of novel adaptations and as a challenge to phylogenetics are so far more obvious and better understood for prokaryotes, as are the mechanisms by which it is effected. © 2011 Elsevier Ltd.
Sawynok J.,Dalhousie University
Drugs and Aging | Year: 2014
Neuropathic pain (NeP) is a significant medical and socioeconomic burden with limited therapeutic options. Elderly patients exhibit a higher incidence of several NeP conditions and pose a particular challenge due to age-related pharmacokinetic and pharmacodynamic issues, comorbid conditions, and polypharmacy, as well as frailty and cognitive decline. Topical analgesics are of interest because of their comparable efficacy to oral agents, good tolerability and safety, and potential to be add-on therapies to oral treatments. In recent years, two topical formulations for NeP have been approved (5 % lidocaine medicated plaster, 8 % capsaicin patch) but are not available in all countries. There are controlled trials and a growing body of open-label reports on their use in clinical care. Some studies provide a post hoc analysis of data in relation to older age (≥65 years), which is useful. The body of evidence relating to topical investigational agents is growing and involves controlled trials as well as individual cases. The largest single body of information is for topical ketamine, administered either alone or combined with other agents (particularly amitriptyline), and some large randomized controlled trials report efficacy. Other large trials involve topical clonidine and further ketamine combinations. Compounding analgesics involves challenges, including uncertain composition (two to five ingredients are used) and concentrations (range 0.5–5 %), as well as the heterogeneity of data that support choices. Nevertheless, case reports and acceptable response rates in larger cohorts are intriguing, and this area merits further investigation in controlled settings as well as continued documentation of clinical experiences. © 2014, Springer International Publishing Switzerland.
Vallis M.,Dalhousie University
Canadian Journal of Diabetes | Year: 2015
Self-management and self-management support are concepts very familiar to those of us in diabetes care. These concepts require openness to understanding the behaviours of persons with diabetes broadly, not only behaviours restricted to the biomedical perspective. Understanding the importance of health behaviour change and working within the Expanded Chronic Care Model define the context within which self-management support should occur. The purpose of this perspective is to identify a potential limitation in existing self-management support initiatives. This potential limitation reflects provider issues, not patient issues; that is, true self-management support might require changes by healthcare providers. Specifically, although behavioural interventions within the context of academic research studies are evidence based, behaviour change interventions implemented in general practice settings might prove less effective unless healthcare providers are able to shift from a practice based on the biomedical model to a practice based on the self-management support model.The purpose of this article is to facilitate effective self-management support by encouraging providers to switch from a model of care based on the expert clinician encountering the uninformed help seeker (the biomedical model) to one guided by collaboration grounded in the principles of description, prediction and choice. Key to understanding the value of making this shift are patient-centered communication principles and the tenets of complexity theory. © 2015 Canadian Diabetes Association.
Corradi N.,University of Ottawa |
Slamovits C.H.,Dalhousie University
Briefings in Functional Genomics | Year: 2011
Microsporidia are a group of highly adapted unicellular fungi that are known to infect a wide range of animals, including humans and species of great economic importance. These organisms are best known for their very simple cellular and genomic features, an adaptive consequence of their obligate intracellular parasitism. In the last decade, the acquisition of a large amount of genomic and transcriptomic data from severalmicrosporidian species has greatly improved our understanding of the consequences of a purely intracellular lifestyle. In particular, genome sequence data from these pathogens has revealed how obligate intracellular parasitism can result in radical changes in the composition and structure of nuclear genomes and how these changes can affect cellular and evolutionary mechanisms that are otherwise well conserved among eukaryotes. This article reviews our current understanding of the genome content and structure ofmicrosporidia, discussing their evolutionary origin and cataloguing themechanisms that have often been involved in their extreme reduction. © The Author 2010. Published by Oxford University Press. All rights reserved.
Nyaga G.N.,Northeastern University |
Whipple J.M.,Michigan State University |
Lynch D.F.,Dalhousie University
Journal of Operations Management | Year: 2010
Firms are building collaborative relationships with their supply chain partners in order to achieve efficiencies, flexibility, and sustainable competitive advantage. However, it is unclear if collaborative relationships provide benefits that compensate for the additional expense associated with such relationships. Further, it is unclear what factors promote successful collaborations. This research examines collaborative relationships in two separate studies using structural equation modeling: one study examines buyers' perceptions and the second study examines suppliers' perceptions. The two studies are then compared using invariance testing in order to determine economic and relational factors that drive satisfaction and performance from each party's perspective. Results show that collaborative activities, such as information sharing, joint relationship effort, and dedicated investments lead to trust and commitment. Trust and commitment, in turn, lead to improved satisfaction and performance. Results from the two independent studies exhibit similarities and differences; while the conceptual model is highly similar, certain paths vary in their significance and/or their importance across buyer and supplier firms such that buyers focus more on relationship outcomes while suppliers look to safeguard their transaction specific investments through information sharing and joint relationship effort. Managerial and theoretical implications of the findings are discussed. © 2009 Elsevier B.V. All rights reserved.
Arnold D.V.,Dalhousie University
Genetic and Evolutionary Computation Conference, GECCO'11 | Year: 2011
We study the behaviour of a (1, λ)-ES that applies a simple repair mechanism to infeasible candidate solutions for the problem of maximising a linear function with a single linear constraint. Integral expressions that describe the strategy's one-generation behaviour are derived and used in a simple zeroth order model for the steady state of the strategy. Applied to the analysis of cumulative step size adaptation, the approach provides an intuitive explanation for the algorithm's behaviour as well as a condition on the setting of its parameters. A comparison with the strategy that re-samples infeasible candidate solutions rather than repairing them is drawn, and the qualitatively different behaviour is explained. Copyright 2011 ACM.
Vallino J.J.,Ecosystems Center |
Algar C.K.,Dalhousie University
Annual Review of Marine Science | Year: 2016
Nearly 100 years ago, Alfred Lotka published two short but insightful papers describing how ecosystems may organize. Principally, Lotka argued that ecosystems will grow in size and that their cycles will spin faster via predation and nutrient recycling so as to capture all available energy, and that evolution and natural selection are the mechanisms by which this occurs and progresses. Lotka's ideas have often been associated with the maximum power principle, but they are more consistent with recent developments in nonequilibrium thermodynamics, which assert that complex systems will organize toward maximum entropy production (MEP). In this review, we explore Lotka's hypothesis within the context of the MEP principle, as well as how this principle can be used to improve marine biogeochemistry models. We need to develop the equivalent of a climate model, as opposed to a weather model, to understand marine biogeochemistry on longer timescales, and adoption of the MEP principle can help create such models. © 2016 by Annual Reviews. All rights reserved.
Holloway K.,Dalhousie University
Social Science and Medicine | Year: 2014
In this article I report on an investigation of the pharmaceutical industry's influence in medical education. Findings are based on fifty semi-structured interviews with medical students in the United States and Canada conducted between 2010 and 2013. Participant responses support the survey-based literature demonstrating that there is clear and pervasive influence of the pharmaceutical industry in medical education. They also challenge the theory that medical students feel entitled to industry gifts and uncritically accept industry presence. I investigate how medical students who are critical of the pharmaceutical industry negotiate its presence in the course of their medical education. Findings suggest that these participants do not simply absorb industry presence, but interpret it and respond in complex ways. Participants were uncomfortable with industry influence throughout their medical training and found multifaceted ways to resist. They struggled with power relations in medical training and the prevailing notion that industry presence is a normal part of medical education. I argue that this pervasive norm of industry presence is located in neoliberal structural transformations within and outside both education and medicine. The idea that industry presence is normal and inevitable represents a challenge for students who are critical of industry. © 2014 .
Kirby J.,Dalhousie University
American Journal of Bioethics | Year: 2016
Critical-care decision making is highly complex, given the need for health care providers and organizations to consider, and constructively respond to, the diverse interests and perspectives of a variety of legitimate stakeholders. Insights derived from an identified set of ethics-related considerations have the potential to meaningfully inform inclusive and deliberative policy development that aims to optimally balance the competing obligations that arise in this challenging, clinical decision-making domain. A potential, constructive outcome of such policy engagement is the collaborative development of an as-fair-as-possible dispute resolution process that incorporates an appropriated-justified, defensible critical-care obligation threshold. © 2016, Copyright © Taylor & Francis Group, LLC.
Lalonde D.H.,Dalhousie University
Clinics in Plastic Surgery | Year: 2011
Wide awake hand surgery means no sedation, no tourniquet, and no general anesthesia for hand surgery. The only medications given to the patient are lidocaine with epinephrine. Lidocaine is for anesthesia, and epinephrine provides hemostasis, which deletes the need for a tourniquet. The advantages are: (1) the ability of the comfortable unsedated tourniquet-free patient to perform active movement of the reconstructed structures during surgery so the surgeon can make alterations to the reconstruction before the skin is closed to improve the outcome of many surgeries; and (2) the deletion of all risks, costs, and inconveniences of sedation and general anesthesia. © 2011 Elsevier Inc.
Bedard K.,Dalhousie University |
Jaquet V.,University Hospitals Geneva Medical Center |
Krause K.-H.,University Hospitals Geneva Medical Center
Free Radical Biology and Medicine | Year: 2012
In mammals, the NADPH oxidase family of enzymes comprises seven members: NOXs 1-5, DUOX1, and DUOX2. All of these enzymes function to move an electron across cellular membranes, transferring it to oxygen to generate the superoxide anion. This generation of reactive oxygen species has important physiological and pathophysiological roles. NOX5 is perhaps the least well understood of these NOX isoforms, in part because the gene is not present in mice or rats. In recent years, however, there has been a rapid increase in our understanding of the NOX5 gene, the structural and biochemical aspects of the NOX5 enzyme, the role NOX5 plays in health and disease, and the development of novel NOX inhibitors. This review takes a look back at some historical aspects of the discovery of NOX5 and summarizes our current understanding of the enzyme. © 2011 Elsevier Inc. All rights reserved.
Adamo S.A.,Dalhousie University
Journal of Experimental Biology | Year: 2013
For millions of years, parasites have altered the behaviour of their hosts. Parasites can affect host behaviour by: (1) interfering with the host's normal immune-neural communication, (2) secreting substances that directly alter neuronal activity via nongenomic mechanisms and (3) inducing genomic- and/or proteomic-based changes in the brain of the host. Changes in host behaviour are often restricted to particular behaviours, with many other behaviours remaining unaffected. Neuroscientists can produce this degree of selectivity by targeting specific brain areas. Parasites, however, do not selectively attack discrete brain areas. Parasites typically induce a variety of effects in several parts of the brain. Parasitic manipulation of host behaviour evolved within the context of the manipulation of other host physiological systems (especially the immune system) that was required for a parasite's survival. This starting point, coupled with the fortuitous nature of evolutionary innovation and evolutionary pressures to minimize the costs of parasitic manipulation, likely contributed to the complex and indirect nature of the mechanisms involved in host behavioural control. Because parasites and neuroscientists use different tactics to control behaviour, studying the methods used by parasites can provide novel insights into how nervous systems generate and regulate behaviour. Studying how parasites influence host behaviour will also help us integrate genomic, proteomic and neurophysiological perspectives on behaviour. © 2013 Published by The Company of Biologists Ltd.
Cohen Jr. M.M.,Dalhousie University
American Journal of Medical Genetics, Part A | Year: 2010
The role of hedgehog signaling is analyzed in relation to the developing endocrine glands: pituitary, ovary, testis, adrenal cortex, pancreas, prostate, and epiphyseal growth. Experimental and pathological correlates of these organs are also discussed. The second section addresses a number of topics. First, the pituitary gland, no matter how hypoplastic, is present in most cases of human holoprosencephaly, unlike animals in which it is always said to be absent. The difference appears to be that animal mutationsand teratogenic models involve both copies of the gene in question, whereas in humans the condition ismost commonly heterozygous. Second, tests of endocrine function are not reported with great frequency, and an early demise in severe cases of holoprosencephaly accounts for this trend. Reported tests of endocrine function are reviewed. Third, diabetes insipidus has been recorded in a number of cases of holoprosencephaly. Its frequency is unknown because it could be masked by adrenal insufficiency in some cases and may not be recognized in others. Because of the abnormal hypothalamic-infundibular region in holoprosencephaly, diabetes insipidus could be caused by a defect in the supra-optic or paraventricular hypothalamic nuclei or in release of ADH via the infundibulum and posterior pituitary. © 2009 Wiley-Liss, Inc.
Sligl W.I.,University of Alberta |
Asadi L.,University of Alberta |
Eurich D.T.,University of Alberta |
Tjosvold L.,University of Alberta |
And 2 more authors.
Critical Care Medicine | Year: 2014
OBJECTIVE:: Some studies suggest better outcomes with macrolide therapy for critically ill patients with community-acquired pneumonia. To further explore this, we performed a systematic review of studies with mortality endpoints that compared macrolide therapy with other regimens in critically ill patients with community-acquired pneumonia. DATA SOURCES:: Studies were identified via electronic databases, grey literature, and conference proceedings through May 2013. STUDY SELECTION:: Using prespecified criteria, two reviewers selected studies; studies of outpatients and hospitalized noncritically ill patients were excluded. DATA EXTRACTION:: Two reviewers extracted data and evaluated bias using the Newcastle-Ottawa Scale. Random effects models were used to generate pooled risk ratios and evaluate heterogeneity (I). DATA SYNTHESIS:: Twenty-eight observational studies (no randomized control trials) were included. Average age ranged from 58 to 78 years and 14-49% were women. In our primary analysis of 9,850 patients, macrolide use was associated with statistically significant lower mortality compared with nonmacrolides (21% [846 of 4,036 patients] vs 24% [1,369 of 5,814]; risk ratio, 0.82; 95% CI, 0.70-0.97; p = 0.02; I = 63%). When macrolide monotherapy was excluded, the macrolide mortality benefit was maintained (21% [737 of 3,447 patients] vs 23% [1,245 of 5,425]; risk ratio, 0.84; 95% CI, 0.71-1.00; p = 0.05; I = 60%). When broadly guideline-concordant regimens were compared, there was a trend to improved mortality and heterogeneity was reduced (20% [511 of 2,561 patients] mortality with beta-lactam/macrolide therapy vs 23% [386 of 1,680] with beta-lactam/ fluoroquinolone; risk ratio, 0.83; 95% CI, 0.67-1.03; p = 0.09; I = 25%). When adjusted risk estimates were pooled from eight studies, macrolide therapy was still associated with a significant reduction in mortality (risk ratio, 0.75; 95% CI, 0.58-0.96; p = 0.02; I = 57%). CONCLUSIONS:: In observational studies of almost 10,000 critically ill patients with community-acquired pneumonia, macrolide use was associated with a significant 18% relative (3% absolute) reduction in mortality compared with nonmacrolide therapies. After pooling data from studies that provided adjusted risk estimates, an even larger mortality reduction was observed. These results suggest that macrolides be considered first-line combination treatment in critically ill patients with community-acquired pneumonia and support current guidelines. © 2013 by the Society of Critical Care Medicine and Lippincott.
Zhang Z.,University of Ottawa |
Donaldson A.A.,Dalhousie University |
Ma X.,Northwest University, China
Biotechnology Advances | Year: 2012
Enzymatic hydrolysis of pre-treated lignocellulosic biomass is an ideal alternative to acid hydrolysis for bio-ethanol production, limited primarily by pre-treatment requirements and economic considerations arising from enzyme production costs and specific activities. The quest for cheaper and better enzymes has prompted years of bio-prospecting, strain optimization through genetic engineering, enzyme characterization for simple and complex lignocellulosic feedstock, and the development of pre-treatment strategies to mitigate inhibitory effects. The recent shift to systematic characterizations of de novo mixtures of purified proteins is a promising indicator of maturation within this field of study, facilitating progression towards feedstock assay-based rapid enzyme mixture optimization. It is imperative that international standards be developed to enable meaningful comparisons between these studies and the construction of a database of enzymatic activities and kinetics, aspects of which are explored here-in. Complementary efforts to improve the economic viability of enzymatic hydrolysis through process integration and reactor design are also considered, where membrane-confinement shows significant promise despite the associated technological challenges. Significant advancements in enzyme technology towards the economic conversion of lignocellulosic biomass should be expected within the next few years as systematic research in enzyme activities conforms to that of traditional reaction engineering. © 2012.
Parker R.W.R.,University of Tasmania |
Tyedmers P.H.,Dalhousie University
Fish and Fisheries | Year: 2014
Compared to a century ago, the world's fishing fleets are larger and more powerful, are travelling further and are producing higher quality products. These developments come largely at a cost of high-fossil fuel energy inputs. Rising energy prices, climate change and consumer demand for 'green' products have placed energy use and emissions among the sustainability criteria of food production systems. We have compiled all available published and unpublished fuel use data for fisheries targeting all species, employing all gears and fishing in all regions of the world into a Fisheries and Energy Use Database (FEUD). Here, we present results of our analysis of the relative energy performance of fisheries since 1990 and provide an overview of the current state of knowledge on fuel inputs to diverse fishing fleets. The median fuel use intensity of global fishery records since 1990 is 639 litres per tonne. Fuel inputs to fisheries vary by several orders of magnitude, with small pelagic fisheries ranking among the world's most efficient forms of animal protein production and crustaceans ranking among the least efficient. Trends in Europe and Australia since the beginning of the 21st century suggest fuel use efficiency is improving, although this has been countered by a more rapid increase in oil prices. Management decisions, technological improvements and behavioural changes can further reduce fuel consumption in the short term, although the most effective improvement to fisheries energy performance will come as a result of rebuilding stocks where they are depressed and reducing over-capacity. © 2014 John Wiley & Sons Ltd.
Wildeman S.,Dalhousie University
Journal of Law, Medicine and Ethics | Year: 2013
The World Health Organization (WHO) has identified mental health as a priority for global health promotion and international development to be targeted through promulgation of evidence-based medical practices, health systems reform, and respect for human rights. Yet these overlapping strategies are marked by tensions as the historical primacy of expert-led initiatives is increasingly subject to challenge by new social movements - in particular, disabled persons' organizations (DPOs). These tensions come into focus upon situating the WHO's mental health policy initiatives in light of certain controversies arising under the Convention on the Rights of Persons with Disabilities (CRPD), particularly as it applies to persons with mental (psychosocial) disabilities. I examine two such controversies - concerning, respectively, the legitimacy of involuntary psychiatric interventions and the legitimacy of regimes of substitute decision-making. These controversies illustrate the radical challenges to global and domestic mental health policy that have gained new momentum through the participation of DPOs in the CRPD process. At the same time, they illustrate the need for ongoing, inclusive forums for deliberation at the nexus of mental health policy and human rights, aimed at enabling human flourishing within a framework of respect for diversity. © 2013 American Society of Law, Medicine & Ethics, Inc.
Cohen M.M.,Dalhousie University
Journal of Craniofacial Surgery | Year: 2013
Three features of cleidocranial dysplasia that are not always appreciated are hypoplastic iliac wings, short stature, and brachydactyly. Because of the pelvic abnormality, pregnant women may require a cesarean delivery. Short stature and brachydactyly indicate more generalized skeletal abnormalities. These are derived from endochondral and intramembranous ossification, but the distinction between these 2 processes is oversimplified because both processes are involved in long bone and clavicular development. Two sections follow: the biology of RUNX2 and the nature of haploinsufficiency in RUNX2 mutations for cleidocranial dysplasia. Copyright © 2013 by Mutaz B. Habal, MD.
Hall R.,Dalhousie University |
Mazer C.D.,Li Ka Shing Knowledge Institute |
Mazer C.D.,University of Toronto
Anesthesia and Analgesia | Year: 2011
In the normal course of the delivery of care, anesthesiologists encounter many patients who are receiving drugs that affect platelet function as a fundamental part of primary and secondary management of atherosclerotic thrombotic disease. There are several antiplatelet drugs available for use in clinical practice and several under investigation. Aspirin and clopidogrel (alone and in combination) have been the most studied and have the most favorable risk-benefit profiles of drugs currently available. Prasugrel was recently approved for patients with acute coronary syndrome undergoing percutaneous interventions. Other drugs such as dipyridamole and cilostazol have not been as extensively investigated. There are several newer investigational drugs such as cangrelor and ticagrelor, but whether they confer significant additional benefits remains to be established. Management of patients who are receiving antiplatelet drugs during the perioperative period requires an understanding of the underlying pathology and rationale for their administration, pharmacology and pharmacokinetics, and drug interactions. Furthermore, the risk and benefit assessment of discontinuing or continuing these drugs should be made bearing in mind the proposed surgery and its inherent risk for bleeding complications as well as decisions relating to appropriate use of general or some form of regional anesthesia. In general, the safest approach to prevent thrombosis seems to be continuation of these drugs throughout the perioperative period except where concerns about perioperative bleeding outweigh those associated with the development of thrombotic occlusion. Knowledge of the pharmacodynamics and pharmacokinetics of antiplatelet drugs may allow practitioners to anticipate difficulties associated with drug withdrawal and administration in the perioperative period including the potential for drug interactions. Copyright © 2011 International Anesthesia Research Society.
Lefort E.C.,Dalhousie University |
Blay J.,University of Waterloo
Molecular Nutrition and Food Research | Year: 2013
Apigenin (4′,5,7-trihydroxyflavone, 5,7-dihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one) is a flavonoid found in many fruits, vegetables, and herbs, the most abundant sources being the leafy herb parsley and dried flowers of chamomile. Present in dietary sources as a glycoside, it is cleaved in the gastrointestinal lumen to be absorbed and distributed as apigenin itself. For this reason, the epithelium of the gastrointestinal tract is exposed to higher concentrations of apigenin than tissues at other locations. This would also be true for epithelial cancers of the gastrointestinal tract. We consider the evidence for actions of apigenin that might hinder the ability of gastrointestinal cancers to progress and spread. Apigenin has been shown to inhibit cell growth, sensitize cancer cells to elimination by apoptosis, and hinder the development of blood vessels to serve the growing tumor. It also has actions that alter the relationship of the cancer cells with their microenvironment. Apigenin is able to reduce cancer cell glucose uptake, inhibit remodeling of the extracellular matrix, inhibit cell adhesion molecules that participate in cancer progression, and oppose chemokine signaling pathways that direct the course of metastasis into other locations. As such, apigenin may provide some additional benefit beyond existing drugs in slowing the emergence of metastatic disease. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Ungar M.,Dalhousie University
Child Abuse and Neglect | Year: 2013
This practice note will show that resilience among children who have been maltreated is the result of multiple protective factors, including the quality of the services provided to children exposed to chronic adversity. This social ecological perspective of resilience suggests that resilience is a process resulting from interactions between individuals and their environments, and depends upon individual characteristics (temperament and personality), the social determinants of health that affect children and children's families, formal interventions by multiple service providers (child welfare, special education, mental health, addictions, public health, and juvenile corrections), and the social policies that influence service provision to vulnerable populations. Clinicians and researchers concerned with the resilience of chronically abused and neglected children have tended to overlook the protective processes unique to children who have been abused that are different from the protective processes that promote positive development among children who have experienced no maltreatment. Most importantly, studies of resilience among maltreated children have rarely investigated the impact child welfare interventions have on the resilience of children who have been maltreated, mistakenly attributing children's abilities to cope to be the result of individual factors rather than the responsiveness of service providers and governments to tailor interventions to children's needs. To enhance the likelihood of resilience among maltreated children, those who design and implement interventions need to address three aspects of resilience-related programming: make social supports and formal services more available and accessibility; design programs flexibly so that they can respond to the differential impact specific types of interventions have on children who are exposed to different forms of maltreatment; and design interventions to be more focused on subpopulations of children who have experienced maltreatment rather than diffuse population-wide initiatives. © 2012 Elsevier Ltd.
Jackman J.E.,Ohio State University |
Gott J.M.,Case Western Reserve University |
Gray M.W.,Dalhousie University
RNA | Year: 2012
The tRNA His guanylyltransferase (Thg1) family of enzymes comprises members from all three domains of life (Eucarya, Bacteria, Archaea). Although the initial activity associated with Thg1 enzymes was a single 3′-to-5′ nucleotide addition reaction that specifies tRNA His identity in eukaryotes, the discovery of a generalized base pair-dependent 3′-to-5′ polymerase reaction greatly expanded the scope of Thg1 family-catalyzed reactions to include tRNA repair and editing activities in bacteria, archaea, and organelles. While the identification of the 3′-to-5′ polymerase activity associated with Thg1 enzymes is relatively recent, the roots of this discovery and its likely physiological relevance were described ∼30 yr ago. Here we review recent advances toward understanding diverse Thg1 family enzyme functions and mechanisms. We also discuss possible evolutionary origins of Thg1 family-catalyzed 3′-to-5′ addition activities and their implications for the currently observed phylogenetic distribution of Thg1-related enzymes in biology. Published by Cold Spring Harbor Laboratory Press. Copyright © 2012 RNA Society.
MacDonald M.,Dalhousie University
Clinical Nurse Specialist | Year: 2010
Purpose: The purpose of this article was to examine the adequacy of the 5 rights (5 R's) for nurses and for including patients in medication administration while considering patient safety. Patient safety related to medication adverse events will be discussed; the 5 R's will be examined and critiqued and the importance of patient-centered care and patient participation in care will be presented. A path forward is offered based on the expressive-collaborative model. Suggestions for introduction of the model are outlined, and implications for practice, research, and education are discussed. Background: Nurses have been guided by the 5 R's of medication administration in both education and practice for many decades. Many have found the 5 R's to be lacking and proceeded to propose the addition of a variety of rights from right indication to the rights of nurses to have legible orders and timely access to information. Patients are no longer passive recipients of care and are choosing to play increasingly greater roles in the process of care. Innovation: In a collaborative patient-centered environment, an expressive-collaborative model of approaching systems of care is needed. In this model, individuals negotiate with one another to find out what people need to know and to strategize on the means to acquiring the necessary information. Providers are no longer expected to be all knowing. Conclusion: Medication administration is no longer simply the 5 R's. Medication administration is a process with many interconnected players including patients. We need to collaboratively restructure medication use in this era in which all involved in the process share the responsibility for a safe medication use system. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.
Russell E.J.,Lakehead University |
Fawcett J.M.,Dalhousie University |
Fawcett J.M.,MRC Cognition and Brain science Unit |
Mazmanian D.,Lakehead University
Journal of Clinical Psychiatry | Year: 2013
Objective: Although pregnant and postpartum women are presumed to be at greater risk of obsessive-compulsive disorder (OCD) than the general population, the evidence has been inconclusive. This meta-analysis provides an estimate of OCD prevalence in pregnant and postpartum women and synthesizes the evidence that pregnant and postpartum women are at greater risk of OCD compared to the general population. Data Sources: An electronic search of Google Scholar, PsycINFO, PsychARTICLES, and PubMed was performed by using the search terms OCD, obsessive-compulsive disorder, pregnancy, postpartum, prevalence, and epidemiology. We SUPPLemented our search with articles referenced in the obtained sources. The search was conducted until August 2012 without date restrictions. Study Selection: We included English-language studies reporting OCD prevalence (diagnosed according to DSM-III-R, DSM-IV, or ICD-10 criteria) in pregnant (12 studies) or postpartum (up to 12 months; 7 studies) women using structured diagnostic interviews. We also included a sample of regionally matched control studies (10 studies) estimating 12-month prevalence in the general female population for comparison. The control studies were limited to those conducted during the same time frame as the pregnant and postpartum studies. Data Extraction: We extracted author name, year of publication, diagnostic measure, sample size, diagnostic criteria, country, assessment time, subject population, and the point prevalence of OCD. Results: Mixed- and random-effects models revealed an increase in OCD prevalence across pregnancy and the postpartum period with the lowest prevalence in the general population (mean = 1.08%) followed by pregnant (mean = 2.07%) and postpartum women (mean = 2.43%). An exploratory analysis of regionally matched risk-ratios revealed both pregnant (mean = 1.45) and postpartum (mean = 2.38) women to be at greater risk of experiencing OCD compared to the general female population, with an aggregate risk ratio of 1.79. Conclusions: Pregnant and postpartum women are more likely to experience OCD compared to the general population. © Copyright 2013 Physicians Postgraduate Press, Inc.
Hall B.K.,Dalhousie University
American Journal of Medical Genetics, Part A | Year: 2014
This overview article highlights active areas of research in craniofacial genetics and developmental biology as reflected in presentations given at the 34th annual meeting of the Society of Craniofacial Genetics and Developmental Biology (SCGDB) in Montreal, Quebec on October 11, 2011. This 1-day meeting provided a stimulating occasion that demonstrated the present status of research in craniofacial genetics and developmental biology and where the field is heading. To accompany the abstracts published in this issue I have selected several themes that emerged from the meeting. After discussing the basis on which craniofacial defects/syndromes are classified and investigated, I address the multi-gene basis of craniofacial syndromes with an examination of the roles of Sox9 and FGF receptors in normal and abnormal craniofacial development. I then turn to the knowledge being gained from population-wide and longitudinal cohort studies and from the discovery of new signaling centers that regulate craniofacial development. © 2014 Wiley Periodicals, Inc.
Linsdell P.,Dalhousie University
Pflugers Archiv European Journal of Physiology | Year: 2014
Chloride permeation through the cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel is subject to voltage-dependent open-channel block by a diverse range of cytoplasmic anions. However, in most cases the ability of these blocking substances to influence the pore opening and closing process has not been reported. In the present work, patch clamp recording was used to investigate the state-dependent block of CFTR by cytoplasmic Pt(NO2)4 2− ions. Two major effects of Pt(NO2)4 2− were identified. First, this anion caused fast, voltage-dependent block of open channels, leading to an apparent decrease in single-channel current amplitude. Secondly, Pt(NO2)4 2− also decreased channel open probability due to an increase in interburst closed times. Interestingly, mutations in the pore that weakened (K95Q) or strengthened (I344K, V345K) interactions with Pt(NO2)4 2− altered blocker effects both on Cl− permeation and on channel gating, suggesting that both these effects are a consequence of Pt(NO2)4 2− interaction with a single site within the pore. Experiments at reduced extracellular Cl− concentration hinted that Pt(NO2)4 2− may have a third effect, possibly increasing channel activity by interfering with channel closure. These results suggest that Pt(NO2)4 2− can enter from the cytoplasm into the pore inner vestibule of both open and closed CFTR channels, and that Pt(NO2)4 2− bound in the inner vestibule blocks Cl− permeation as well as interfering with channel opening and, perhaps, channel closure. Implications for the location of the channel gate in the pore, and the operation of this gate, are discussed. © 2014, Springer-Verlag Berlin Heidelberg.
Wittmann W.,Umea University |
Iulianella A.,Dalhousie University |
Gunhaga L.,Umea University
Developmental Biology | Year: 2014
Signaling pathways and transcription factors are crucial regulators of vertebrate neurogenesis, exerting their function in a spatial and temporal manner. Despite recent advances in our understanding of the molecular regulation of embryonic neurogenesis, little is known regarding how different signaling pathways interact to tightly regulate this process during the development of neuroepithelia. To address this, we have investigated the events lying upstream and downstream of a key neurogenic factor, the Cut-like homeodomain transcription factor-2 (Cux2), during embryonic neurogenesis in chick and mouse. By using the olfactory epithelium as a model for neurogenesis we have analyzed mouse embryos deficient in Cux2, as well as chick embryos exposed to Cux2 silencing (si) RNA or a Cux2 over-expression construct. We provide evidence that enhanced BMP activity increases Cux2 expression and suppresses olfactory neurogenesis in the chick olfactory epithelium. In addition, our results show that up-regulation of Cux2, either BMP-induced or ectopically over-expressed, reduce Delta1 expression and suppress proliferation. Interestingly, the loss of Cux2 activity, using mutant mice or siRNA in chick, also diminishes neurogenesis, Notch activity and cell proliferation in the olfactory epithelium. Our results suggest that controlled low levels of Cux2 activity are necessary for proper Notch signaling, maintenance of the proliferative pool and ongoing neurogenesis in the olfactory epithelium. Thus, we demonstrate a novel conserved mechanism in vertebrates in which levels of Cux2 activity play an important role for ongoing neurogenesis in the olfactory epithelium. © 2014 The Authors.
Sterling S.M.,Dalhousie University |
Sterling S.M.,University Pierre and Marie Curie |
Ducharne A.,University Pierre and Marie Curie |
Polcher J.,University Pierre and Marie Curie
Nature Climate Change | Year: 2013
Floods and droughts cause perhaps the most human suffering of all climate-related events; a major goal is to understand how humans alter the incidence and severity of these events by changing the terrestrial water cycle. Here we use over 1,500 estimates of annual evapotranspiration and a database of global land-cover change to project alterations of global scale terrestrial evapotranspiration (TET) from current anthropogenic land-cover change. Geographic modelling reveals that land-cover change reduces annual TET by approximately 3,500 km 3 yr -1 (5%) and that the largest changes in evapotranspiration are associated with wetlands and reservoirs. Land surface model simulations support these evapotranspiration changes, and project increased runoff (7.6%) as a result of land-cover changes. Next we create a synthesis of the major anthropogenic impacts on annual runoff and find that the net result is an increase in annual runoff, although this is uncertain. The results demonstrate that land-cover change alters annual global runoff to a similar or greater extent than other major drivers, affirming the important role of land-cover change in the Earth System. Last, we identify which major anthropogenic drivers to runoff change have a mean global change statistic that masks large regional increases and decreases: land-cover change, changes in meteorological forcing, and direct CO 2 effects on plants. © 2013 Macmillan Publishers Limited. All rights reserved.
Blake J.T.,Dalhousie University
Transfusion | Year: 2014
Canadian Blood Services runs approximately 16,000 donor clinics annually. While there were more than 220 different clinic configurations used in 2011 and 2012, 67% of all clinic configurations followed one of 51 standard models. As part of operational planning for current and future configurations it was necessary for Canadian Blood Services to calculate staffing requirements for standard clinic models. In this article we present a method that incorporates both cost control and impact on donor experience. We calculate staffing requirements to minimize costs, but adjust using queuing theory to ensure donor wait time metrics are met. The method can be applied in a wide variety of situations. Although developed for a particular study, the methods described in this article can be applied in a wide variety of situations. A case study in which the model is used to review existing staffing arrangements at Canadian Blood Services is presented. The staffing model can be used to balance the requirements of minimizing staffing costs with that of ensuring that donors do not suffer unnecessary delays. Moreover, in an example application, savings of 3.4% were identified through the modeling process. © 2013 American Association of Blood Banks.
Simpson C.,Dalhousie University
HEC Forum | Year: 2012
There are several important conceptual issues and questions about the practice of healthcare ethics that can, and should, inform the development of any practice standards. This paper provides a relatively short overview of seven of these issues, with the invitation for further critical reflection and examination of their relevance to and implications for practice standards. The seven issues described include: diversity (from the perspective of training and experience); moral expertise and authority/influence; being an insider or outsider; flexibility and adaptability (for local contexts of practice); the relative weighting of procedural and normative aspects of ethics practice; making mistakes or errors; and conflicts of interest in practice. © Springer Science+Business Media B.V. 2012.
O'Dor R.K.,Dalhousie University
Canadian Journal of Zoology | Year: 2013
Squid have been studied extensively since 1982 to quantitatively measure their cost of locomotion and compare it with costs for fishes that are their primary competitors in the ocean. Early work focused on oxygen consumption in swim tunnels and led to the use of jet pressure tags to relate captive studies to behaviour in nature. Dosidicus gigas (d'Orbigny, 1835) (jumbo flying squid or Humboldt squid), which has expanded its range more than 10-fold, is used to illustrate how "live fast, die young" squid can out compete fishes in changing times by both swimming and flying. Recent work has provided quantitative data on the costs of flying and this report provides some comparisons. Costs of flight in nature require new technology, which has fortunately arrived just in time. Accelerometry tags can now provide similar and perhaps better data on travel rate in nature, both in water and in air. These work on both squid and fish, so more and better comparisons are becoming possible.
El-Naggar W.,Dalhousie University |
McNamara P.J.,University of Toronto
Journal of Perinatology | Year: 2012
Objective: To explore physicians experiences and views related to resuscitation practice of preterm infants at birth, and determine whether the Canadian modifications of 2006 Neonatal Resuscitation Program (NRP) guidelines have been accepted by neonatologists. Study Design: Neonatologists (n=146) at 25 tertiary neonatal intensive care units (NICUs) across Canada were contacted via email to participate in a web-based survey about their practice regarding resuscitation of preterm infants in the delivery room (DR). Result: In all, 78 respondents (53%) from 23 centres completed the survey. Participants reported significant variability in temperature control measures. Hypothermia, 36.5°C on NICU admission, was reported by 49% of respondents. Room air is used by 59% of respondents to initiate resuscitation. The majority (91%) of participants use pulse oximetry to titrate oxygen administration. Although more than two thirds (69%) of respondents target an oxygen saturation range of 85 to 92%, 51% of respondents would allow 5 to 10 min for the oxygen saturation to reach the target level. Carbon dioxide detectors are commonly used to confirm endotracheal tube placement (90%). Although respondents (96%) agree on the use of positive end- expiratory pressure (PEEP), when providing positive pressure ventilation (PPV), only 60% would initiate PPV with a pre-set peak inspiratory pressure, mostly 20 cm H2O. Conclusion: DR resuscitation practices are highly variable in Canadian NICU's and the currently recommended NRP guidelines are not uniformly followed. Factors leading to variability and discordance in practice should be investigated to facilitate better compliance. © 2012 Nature America, Inc. All rights reserved.
Madureira P.A.,University of Algarve |
Waisman D.M.,Dalhousie University
International Journal of Molecular Sciences | Year: 2013
Hydrogen peroxide (H2O2) is an important second messenger in cellular signal transduction. H2O2-dependent signalling regulates many cellular processes, such as proliferation, differentiation, migration and apoptosis. Nevertheless, H2O2 is an oxidant and a major contributor to DNA damage, protein oxidation and lipid peroxidation, which can ultimately result in cell death and/or tumourigenesis. For this reason, cells have developed complex antioxidant systems to scavenge ROS. Recently, our laboratory identified the protein, annexin A2, as a novel cellular redox regulatory protein. Annexin A2 possesses a reactive cysteine residue (Cys-8) that is readily oxidized by H2O2 and subsequently reduced by the thioredoxin system, thereby enabling annexin A2 to participate in multiple redox cycles. Thus, a single molecule of annexin A2 can inactivate several molecules of H2O2. In this report, we will review the studies detailing the reactivity of annexin A2 thiols and the importance of these reactive cysteine(s) in regulating annexin A2 structure and function. We will also focus on the recent reports that establish novel functions for annexin A2, namely as a protein reductase and as a cellular redox regulatory protein. We will further discuss the importance of annexin A2 redox regulatory function in disease, with a particular focus on tumour progression. © 2013 by the authors; licensee MDPI, Basel, Switzerland.
Tajbakhsh M.M.,Dalhousie University
Computers and Industrial Engineering | Year: 2010
We consider a continuous-review (Q, r) inventory model with a fill rate service constraint and relax the assumption that the distribution of lead time demand is known. We adopt a distribution free approach: We assume that only the first two moments of the lead time demand distribution are known, and then, optimize the policy parameters against the worst possible distribution. We are able to derive closed-form expressions for the optimal order quantity and reorder point. © 2010 Elsevier Ltd. All rights reserved.
Reithmeier L.,Dalhousie University
PloS one | Year: 2013
Ectomycorrhizal fungi (ECMF) are an important biotic factor in the survival of conifer seedlings under stressful conditions and therefore have the potential to facilitate conifer establishment into alpine and tundra habitats. In order to assess patterns of ectomycorrhizal availability and community structure above treeline, we conducted soil bioassays in which Picea mariana (black spruce) seedlings were grown in field-collected soils under controlled conditions. Soils were collected from distinct alpine habitats, each dominated by a different ectomycorrhizal host shrub: Betula glandulosa, Arctostaphylos alpina or Salix herbacaea. Within each habitat, half of the soils collected contained roots of ectomycorrhizal shrubs (host (+)) and the other half were free of host plants (host(-)). Forest and glacial moraine soils were also included for comparison. Fungi forming ectomycorrhizae during the bioassays were identified by DNA sequencing. Our results indicate that ECMF capable of colonizing black spruce are widespread above the current tree line in Eastern Labrador and that the level of available inoculum has a significant influence on the growth of seedlings under controlled conditions. Many of the host(-) soils possessed appreciable levels of ectomycorrhizal inoculum, likely in the form of spore banks. Inoculum levels in these soils may be influenced by spore production from neighboring soils where ectomycorrhizal shrubs are present. Under predicted temperature increases, ectomycorrhizal inoculum in soils with host shrubs as well as in nearby soils without host shrubs have the potential to facilitate conifer establishment above the present tree line.
Abidi S.R.,Dalhousie University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011
Handling comorbid diseases in a decision support framework is a challenging problem as it demands the synthesis of clinical procedures for two or more diseases whilst maintaining clinical pragmatics. In this paper we present a knowledge management approach for handling comorbid diseases by the systematic alignment of the Clinical Pathways (CP) of comorbid diseases. Our approach entails: (a) knowledge synthesis to derive disease-specific CP from evidence-bases sources; (b) knowledge modeling to abstract medical and procedural knowledge from the CP; (c) knowledge representation to computerize the CP in terms of a CP ontology; and (d) knowledge alignment by aligning multiple CP to develop a unified CP knowledge model for comorbid diseases. We present the COMET system that provides decision support to handle comorbid cardiac heart failure and atrial fibrillation. © 2011 Springer-Verlag.
Doolittle W.F.,Dalhousie University |
Zhaxybayeva O.,Environmental Proteomics NB Inc.
BioScience | Year: 2010
Metagenomics is a complex of research methodologies aimed at characterizing microbial communities and cataloging microbial diversity and distribution without isolating or culturing organisms. This approach will unavoidably engender new ways of thinking about microbial ecology that supplant the concept of "species." This concept-thanks to comparative-genomicshas in any case become increasingly unsustainable, either as a way of binning diversity or as a biological reality. Communities will become the units of evolutionary and ecological study. Although metagenomic methods will increasingly find uses in protistology and mycology, the emphasis so far has been, and our focus here will be, on prokaryotes (bacteria and archaea). © 2010 by American Institute of Biological Sciences.
Demas G.E.,Indiana University Bloomington |
Adamo S.A.,Dalhousie University |
French S.S.,Utah State University
Functional Ecology | Year: 2011
1.Communication among cells, tissues and organ systems is essential for survival. Vertebrate and invertebrate animals rely primarily on three physiological systems for intra-organismal communication: the nervous, endocrine and immune systems. Rather than acting independently of one another, these systems communicate in an integrated fashion to coordinate suites of species-appropriate physiological and behavioural responses. 2.Our understanding of how these three systems are coordinated remains incomplete, in part because the importance of the immune system as part of this regulatory network has only recently been recognized. In contrast to the well-established integrative approach to the study of the endocrine and nervous systems, the study of immunity has traditionally occurred in relative isolation from other physiological systems. Immunity was typically considered to be largely buffered from environmental perturbations. 3.In the last several decades, however, this simplistic view has changed dramatically; we now know that a wide variety of extrinsic and intrinsic factors can affect immune responses (reviewed in: Ader, Felten & Cohen 2001). This altered perspective has led to the development of new scientific disciplines including psychoneuroimmunology (Ader & Cohen 1981) and ecological immunology (Sheldon & Verhulst 1996). 4.These new research fields focus on the connections among the endocrine, nervous and immune systems. These fields also examine how environmental factors influence interactions among the three systems, and the implications of these interactions for behaviour and host defence. A comparative approach will benefit the search for the adaptive functions of these interactions. © 2010 The Authors. Functional Ecology © 2010 British Ecological Society.
Doelle M.,Dalhousie University
Climate Law | Year: 2016
This article offers an overview of the two key outcomes of the 2015 Paris climate negotiations, the Paris cop decision, and the Paris Agreement. Collectively, they chart a new course for the un climate regime that started in earnest in Copenhagen in 2009. The Paris Agreement represents a path away from the top-down approach and rigid differentiation among parties reflected in the Kyoto Protocol, toward a bottom-up and flexible approach focused on collective long-term goals and principles. It represents an approach to reaching these long-term goals that is focused on self-differentiation, support, transparency, and review. The article highlights the key elements of the agreement reached in Paris, including its approach to mitigation, adaptation, loss and damage, finance, transparency, and compliance. © 2016 by Koninklijke Brill NV, Leiden, The Netherlands.
Wranik D.,Dalhousie University
Health Economics, Policy and Law | Year: 2012
This paper assesses which policy-relevant characteristics of a healthcare system contribute to health-system efficiency. Health-system efficiency is measured using the stochastic frontier approach. Characteristics of the health system are included as determinants of efficiency. Data from 21 OECD countries from 1970 to 2008 are analysed. Results indicate that broader health-system structures, such as Beveridgian or Bismarckian financing arrangements or gatekeeping, are not significant determinants of efficiency. Significant contributors to efficiency are policy instruments that directly target patient behaviours, such as insurance coverage and cost sharing, and those that directly target physician behaviours, such as physician payment methods. From the perspective of the policymaker, changes in cost-sharing arrangements or physician remuneration are politically easier to implement than changes to the foundational financing structure of the system. © 2011 Cambridge University Press.
Obrovac M.N.,Dalhousie University |
Chemical Reviews | Year: 2014
Most studies set out to make materials that improve on the specific capacity of graphite, usually without regard to average voltage, volumetric capacity, or the many other properties listed above that are more applicable to implementation in practical cells. One difficulty in choosing proper metrics for anodes stems from basic electrochemistry: it is not possible to calculate the energy of a single electrode. To provide motivation for using alloy anode materials and a framework for comparison, key performance metrics need to be defined. It is well-known that the volumetric and specific capacities of the active elements are far greater than that of graphite. Because all alloys expand considerably during lithiation, this volume must be accommodated somewhere within a battery. To make more informative performance comparisons, it is necessary to use a cell model, preferably one that is most representative of alloy materials application.
Manchia M.,Dalhousie University
Bipolar disorders | Year: 2013
Suicide is a significant cause of mortality in patients with major affective disorders (MAD), and suicidal behavior and MAD co-aggregate in families. However, the transmission of suicidal behavior is partially independent from that of MAD. We analyzed the lifetime prevalence of completed and attempted suicides in a large sample of families with bipolar disorder (BD), its relation to family history of MAD and BD, and the contribution of clinical and treatment factors to the risk of suicidal behavior. We studied 737 families of probands with MAD with 4919 first-degree relatives (818 affected, 3948 unaffected, and 153 subjects with no information available). Lifetime psychiatric diagnoses and suicidal behavior in first-degree relatives were assessed using semi-structured interviews, family history methods, and reviews of clinical records. Cox proportional hazard and logistic regression models were used to investigate the role of clinical covariates in the risk of suicidal behavior, and in the prevalence of MAD and BD. The estimated lifetime prevalence of suicidal behavior (attempted and completed suicides) in 737 probands was 38.4 ± 3.0%. Lithium treatment decreased suicide risk in probands (p = 0.007). In first-degree relatives, a family history of suicidal behavior contributed significantly to the joint risk of MAD and suicidal behavior (p = 0.0006). The liability to suicidal behavior is influenced by genetic factors (particularly family history of suicidal behavior and MAD). Even in the presence of high genetic risk for suicidal behavior, lithium treatment decreases suicide rates significantly. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Bingeman E.,Dalhousie University
Journal of Evaluation in Clinical Practice | Year: 2016
Since its inception in the early 1990s, evidence-based medicine (EBM) has become the dominant epistemic framework for Western medical practice. However, in light of powerful criticisms against EBM, alternatives such as casuistic medicine have been gaining support in both the medical and philosophical community. In the absence of empirical evidence in support of the claim that EBM improves patient outcomes, and in light of considerations that it is unlikely that such evidence will be forthcoming, another standard is needed to assess EBM against its alternatives. In this paper, I propose a set of criteria for this purpose based on Helen Longino's criteria for assessing the objectivity of a knowledge productive community. I then apply these criteria to assess EBM against a casuistic framework for medical knowledge. I argue that EBM's strict adherence to a hierarchical organization of knowledge can reasonably be expected to block it from fulfilling a high level of objectivity. A casuistic framework, on the other hand, because it emphasizes critical evaluation in conjunction with the flexibility of a case-based approach, could be expected to better facilitate a more optimal epistemic community. © 2016 John Wiley & Sons, Ltd.
Abidi S.,Dalhousie University
Pediatrics in Review | Year: 2013
On the basis of strong research evidence (1)(3) very early onset (VEOS) and early onset schizophrenia (EOS) carry significant morbidity and mortality risks for children and adolescents. On the basis of strong research evidence, the pathogenesis of EOS is linked to a dysregulation of dopamine and morphologic brain changes. (6)(7) On the basis of some research evidence and consensus, development of schizophrenia is the result of the interplay between genetic and environmental risk factors. (4) On the basis of strong research evidence, antipsychotic medications are the cornerstones of treatment for EOS. (11)(12)(13) On the basis of some research evidence and consensus, (13) treatment for schizophrenia should be timely, multimodal and multidisciplinary, including both pharmacologic and nonpharmacologic modalities to optimize recovery.
Duffy A.,Dalhousie University |
Duffy A.,Flourish Mood Disorders Clinical Research Program
Canadian Journal of Psychiatry | Year: 2010
Longitudinal high-risk research has provided convergent evidence that major mood and psychotic disorders often develop from nonspecific antecedents in predisposed people over time and development. For example, bipolar disorder (BD) appears to evolve from nonspecific childhood antecedents, including anxiety and sleep problems, followed by adjustment and minor mood disturbances through early adolescence, culminating in major mood episodes in later adolescence and early adulthood. Therefore, the current cross-sectional symptom-based diagnostic approach requires rethinking: it considers neither the familial risk nor the longitudinal clinical course, with the consequence that the early stages of illness are not recognized as belonging to the end-stage disorder. Emerging evidence of identifiable clinical stages in the development of BD has tremendous potential for early identification, development of stage-specific treatments, and advancing our understanding of the pathophysiology associated with illness onset and progression. The clinical staging model also has direct implications for the optimal organization of clinical services for high-risk youth. Specifically, specialty psychiatric programs are needed that break down traditional institutional barriers to provide surveillance and timely comprehensive psychiatric assessment during the entire risk period, from childhood through to early adulthood. In this regard, the development of specialty psychiatric programs aiming to identify youth in the early stages of evolving psychosis are substantially ahead of services for youth in the early stages of evolving major mood disorders.
Schmidt B.,Childrens Hospital of Philadelphia |
Schmidt B.,McMaster University |
Whyte R.K.,Dalhousie University |
Asztalos E.V.,University of Toronto |
And 5 more authors.
JAMA - Journal of the American Medical Association | Year: 2013
Importance: The goal of oxygen therapy is to deliver sufficient oxygen to the tissues while minimizing oxygen toxicity and oxidative stress. It remains uncertain what values of arterial oxygen saturations achieve this balance in preterm infants. Objective: To compare the effects of targeting lower or higher arterial oxygen saturations on the rate of death or disability in extremely preterm infants. Design, Setting, and Participants: Randomized, double-blind trial in 25 hospitals in Canada, the United States, Argentina, Finland, Germany, and Israel in which 1201 infants with gestational ages of 23 weeks 0 days through 27 weeks 6 days were enrolled within 24 hours after birth between December 2006 and August 2010. Follow-up assessments began in October 2008 and ended in August 2012. Interventions: Study participants were monitored until postmenstrual ages of 36 to 40 weeks with pulse oximeters that displayed saturations of either 3% above or below the true values. Caregivers adjusted the concentration of oxygen to achieve saturations between 88% and 92%, which produced 2 treatment groups with true target saturations of 85% to 89% (n=602) or 91% to 95% (n=599). Alarms were triggered when displayed saturations decreased to 86% or increased to 94%. Main Outcomes and Measures: The primary outcome was a composite of death, gross motor disability, cognitive or language delay, severe hearing loss, or bilateral blindness at a corrected age of 18 months. Secondary outcomes included retinopathy of prematurity and brain injury. Results: Of the 578 infants with adequate data for the primary outcome who were assigned to the lower target range, 298 (51.6%) died or survived with disability compared with 283 of the 569 infants (49.7%) assigned to the higher target range (odds ratio adjusted for center, 1.08; 95% CI, 0.85 to 1.37; P=.52). The rates of death were 16.6% for those in the 85% to 89% group and 15.3% for those in the 91% to 95% group (adjusted odds ratio, 1.11; 95% CI, 0.80 to 1.54; P=.54). Targeting lower saturations reduced the postmenstrual age at last use of oxygen therapy (adjusted mean difference, -0.8 weeks; 95% CI, -1.5 to -0.1; P=.03) but did not alter any other outcomes. Conclusion and Relevance In extremely preterm infants, targeting oxygen saturations of 85% to 89% compared with 91% to 95% had no significant effect on the rate of death or disability at 18 months. These results may help determine the optimal ©2013 American Medical Association. All rights reserved.
Cohen M.M.,Dalhousie University
American Journal of Medical Genetics, Part C: Seminars in Medical Genetics | Year: 2010
This review of holoprosencephaly provides a mythologic and teratologic distillate of the subject under the following headings: Babylonian tablets; Greek mythology; pictures from the 16th through the 20th Centuries; 19th Century teratology; history of more modern concepts and their terminologies; and ocean-going ships named "Cyclops." © 2010 Wiley-Liss, Inc.
Cohen Jr. M.M.,Dalhousie University
American Journal of Medical Genetics, Part A | Year: 2010
In vertebrate hedgehog signaling, hedgehog ligands are processed to become bilipidated and then multimerize, which allows them to leave the signaling cell via Dispatched 1 and become transported via glypicans and megalin to the responding cells. Hedgehog then interacts with a complex of Patched 1 and Cdo/ Boc, which activates endocytic Smoothened to the cilium. Patched 1 regulates the activity of Smoothened (1) via Vitamin D3, which inhibits Smoothened in the absence of hedgehog ligand or (2) via oxysterols, which activate Smoothened in the presence of hedgehog ligand. Hedgehog ligands also interact with Hip1, Patched 2, and Gas1, which regulate the range as well as the level of hedgehog signaling. In vertebrates, Smoothened is shortened at its C-terminal end and lacks most of the phosphorylation sites of importance in Drosophila. Cos2, also of importance in Drosophila, plays no role in mammalian transduction, nor do its homologs Kif7 and Kif27. The cilium may provide a function analogous to that of Cos2 by linking Smoothened to the modulation of Gli transcription factors. Disorders associated with the hedgehog signaling network follow, including nevoid basal cell carcinoma syndrome, holoprosencephaly, Smith-Lemli-Opitz syndrome, Greig cephalopolysyndactyly syndrome, Pallister-Hall syndrome, Carpenter syndrome, and Rubinstein-Taybi syndrome. © 2010 Wiley-Liss, Inc.
MacRae T.H.,Dalhousie University
Cellular and Molecular Life Sciences | Year: 2010
Diapause entails molecular, physiological and morphological remodeling of living animals, culminating in a dormant state characterized by enhanced stress tolerance. Molecular mechanisms driving diapause resemble those responsible for biochemical processes in proliferating cells and include transcriptional, post-transcriptional and post-translational processes. The results are directed gene expression, differential mRNA and protein accumulation and protein modifications, including those that occur in response to changes in cellular redox potential. Biochemical pathways switch, metabolic products change and energy production is adjusted. Changes to biosynthetic activities result for example in the synthesis of molecular chaperones, late embryogenesis abundant (LEA) proteins and protective coverings, all contributing to stress tolerance. The purpose of this review is to consider regulatory and mechanistic strategies that are potentially key to metabolic control and stress tolerance during diapause, while remembering that organisms undergoing diapause are as diverse as the processes itself. Some of the parameters described have well-established roles in diapause, whereas the evidence for others is cursory. © Springer Basel AG 2010.
Cohen M.M.,Dalhousie University
American Journal of Medical Genetics, Part A | Year: 2012
Topics discussed include asymmetry of the brain; prosopagnosia with asymmetric involvement; the blaspheming brain; effects of the numbers of X chromosomes on brain asymmetry; normal facial asymmetry; kissing asymmetry; left- and right-handedness; left-sided baby cradling; Nodal signaling and left/right asymmetry; primary cilium and left/right asymmetry in zebrafish; right/left asymmetry in snails; species differences in Shh and Fgf8; primary cilium in vertebrate asymmetry; Hedgehog signaling on the cilium; Wnt signaling on the cilium; situs solitus, situs inversus, and situs ambiguus (heterotaxy); ciliopathies; right-sided injuries in trilobites; unilateral ocular use in the octopus; fiddler crabs; scale-eating cichlids; narwhals; left-footed parrots; asymmetric whisker use in rats; and right-sided fatigue fractures in greyhounds. © 2012 Wiley Periodicals, Inc.
Selinger P.,Dalhousie University
Quantum Information and Computation | Year: 2014
We give an efficient randomized algorithm for approximating an arbitrary element of SU(2) by a product of Clifford+T operators, up to any given error threshold ε > 0. Under a mild hypothesis on the distribution of primes, the algorithm’s expected runtime is polynomial in log(1/ε). If the operator to be approximated is a z-rotation, the resulting gate sequence has T -count K+4 log2 (1/ε), where K is approximately equal to 10. We also prove a worst-case lower bound of K + 4 log2 (1/ε), where K = -9, so that our algorithm is within an additive constant of optimal for certain z-rotations. For an arbitrary member of SU(2), we achieve approximations with T -count K + 12 log2(1/ε). By contrast, the Solovay-Kitaev algorithm achieves T -count O(logc(1/ε)), where c is approximately 3.97. © Rinton Press.
Paulus M.,Ludwig Maximilians University of Munich |
Moore C.,Dalhousie University
Advances in Child Development and Behavior | Year: 2012
Early prosocial development has become a topic of great interest in recent years as experimental studies have provided evidence that instances of prosocial action can already be found in the second year of life. In this contribution, we review the recent literature on young children's production of prosocial actions, in particular helping, sharing, and comforting, and their understanding of others' prosocial behavior. We summarize the novel insights gained by recent studies and point to directions for future studies. Overall, we suggest that while the field consists of considerable knowledge about the developmental timeline of prosocial behavior, more research is needed to examine and better understand underlying social-cognitive mechanisms. © 2012 Elsevier Inc.
Gardner D.M.,Dalhousie University
Canadian Journal of Psychiatry | Year: 2014
There is little doubt that undergraduate and post-graduate training of physicians, pharmacists, and nurses is insufficient to prepare them to use psychotropics safely and effectively, especially in the context of their expanded off-label uses. Therefore, the development of competencies in psychotropic prescribing needs to be approached as a long-term, practice-based learning commitment. Proposed are the abilities and knowledge components necessary for safe and effective use of psychotropics. Typical challenges in prescribing for chronic and recurrent illnesses include highly variable responses and tolerability, drug interactions, and adverse effects that can be serious, irreversible, and even fatal. Prescribing psychotropics is further complicated by negative public and professional reports and growing patient concerns about the quality of care, and questions about the efficacy, safety, and addictive risks of psychotropics. Increased efforts are needed to enhance clinical training and knowledge in psychopharmacology among trainees and practising clinicians, with more comprehensive and sustained attention to the assessment of individual patients, and greater reliance on patient education and collaboration. Improved competence in psychotropic prescribing should lead to more informed, thoughtful, and better-targeted applications as one component of more comprehensive clinical care.
Mahmoudi M.,Pasteur Institute of Iran |
Mahmoudi M.,Tehran University of Medical Sciences |
Hosseinkhani H.,National Yang Ming University |
Hosseinkhani M.,Mount Sinai School of Medicine |
And 6 more authors.
Chemical Reviews | Year: 2011
Fetal stem cells, which can be isolated from the organs of fetuses, differentiate along multiple lineages. Their advantages over their adult counterparts include better intrinsic homing and engraftment and lower immunogenicity, and they are less ethically contentious. It is noteworthy that Mesenchymal Stem Cells (MSC) can be activated and mobilized at the site of damaged tissue. Since vascular delivery suffers from a pulmonary first pass effect, direct or systemic injection of MSCs into the damaged tissue is preferred, particularly in the case of versatile tissue ischemia. Ultrasound applies acoustic energy with a frequency above human hearing (20 kHz). Ultrasound imaging or sonography scanners operate between 2 and 13 MHz. The frequency determines the image's spatial resolution and the penetration depth into the examined patient.
Eajal A.A.,University of Tripoli |
El-Hawary M.E.,Dalhousie University
IEEE Transactions on Power Delivery | Year: 2010
Shunt capacitors installation in distribution systems requires optimal placement and sizing. More harmonics are being injected into distribution systems. Adding shunt capacitors may lead to high distortion levels. The capacitor placement and sizing problem is a nonlinear integer optimization problem, with locations and ratings of shunt capacitors being discrete values. The goal is to minimize the overall cost of the total real power loss and that of shunt capacitors while satisfying operating and power quality constraints. This paper proposes to solve the problem using particle swarm optimization (PSO). A discrete version of PSO is combined with a radial distribution power flow algorithm (RDPF) to form a hybrid PSO algorithm (HPSO). The former is employed as a global optimizer to find the global optimal solution, while the latter is used to calculate the objective function and to verify bus voltage limits. To include the presence of harmonics, the developed HPSO was integrated with a harmonic power flow algorithm (HPF). The proposed (HPSO-HPF)-based approach is tested on an IEEE 13-bus radial distribution system (13-Bus-RDS). The findings clearly demonstrate the necessity of including harmonics in optimal capacitor placement and sizing to avoid any possible problems associated with harmonics. © 2010 IEEE.
Lalonde D.,Dalhousie University
Hand Clinics | Year: 2014
The minimally invasive tumescent local anesthesia technique used in wide-awake hand surgery is having an impact in hand surgery practice. Patients spend less time and money and get to speak to their surgeon and receive education during the surgery itself. Improvements in operations such as flexor tendon repair have happened, because surgeons can see movement during the case and make adjustments before the skin is closed. Surgeons can perform more cases in the same amount of time with fewer personnel. The cost of the surgery is decreased, as all expenses surrounding the provision of sedation are removed. © 2014 Elsevier Inc.
Flavelle S.C.,Dalhousie University
Archives of Pediatrics and Adolescent Medicine | Year: 2011
Objective: To provide a unified description of an adolescent's experience of living with and dying of cancer. Design: Qualitative analysis using phenomenological methods. Setting: Izaak Walton Killam Health Centre, Halifax, Nova Scotia, Canada. Patient: A 15-year-old boy who was diagnosed as having osteosarcoma in 2003 and died of his disease 1 year later. Intervention: Analysis of his 90-page journal that spanned 3 months just before his death. Main Outcome Measures: Identification and clustering of key themes to capture the essence of his experience. Results: Five main themes that surfaced during analysis of the journal were adolescent development, escape from illness, changing relationships, symptoms, and spirituality. Conclusion: A single case study can provide valuable information in a field such as pediatric palliative care in which the patient's perspective may be difficult to access or ascertain. © 2011 American Medical Association.
Herder M.,Dalhousie University
Journal of Law, Medicine and Ethics | Year: 2014
Efforts to foster transparency in biopharmaceutical regulation are well underway: drug manufacturers are, for example, legally required to register clinical trials and share research results in the United States and Europe. Recently, the policy conversation has shifted toward the disclosure of clinical trial data, not just trial designs and basic results. Here, I argue that clinical trial registration and disclosure of clinical trial data are necessary but insufficient. There is also a need to ensure that regulatory decisions that flow from clinical trials - whether positive (i.e., product approvals) or negative (i.e., abandoned products, product refusals, and withdrawals) - are open to outside scrutiny. Further, a jurisprudence of drug regulation is needed. I develop two arguments motivated by (1) innovation concerns and (2) the value of good governance in support of openly publishing all final decisions for approved, abandoned, refused, and withdrawn products. After articulating why greater transparency in regulatory decision-making is needed, I distil four essential features of a jurisprudence of drug regulation that prescribe policy changes in terms not only of the transparency of regulatory outcomes and the underlying reasoning, but also regulatory organization. © 2014 American Society of Law, Medicine & Ethics, Inc.
Susko E.,Dalhousie University
Molecular Biology and Evolution | Year: 2014
This article considers two similar likelihood-based test statistics for comparing two fixed trees, the Kishino-Hasegawa (KH) test statistic and the likelihood ratio (LR) statistic, as well as a number of different methods for determining thresholds to declare a significant result. An explanation is given for why the KH test, which uses the KH test statistic and normal theory thresholds, need not give correct type I error probabilities under the appropriate null hypothesis. Simulations show that the KH test tends to give much smaller type I error probabilities than expected. The article presents a computationally efficient normal-theory parametric bootstrap method for determining better KH test statistic thresholds. For the LR statistic, existing mixture of chi-squares results for determining thresholds are extended to cases in which a tree with two or three zero edge-lengths exhibits the two trees being compared. The resulting chi-bar test and use of the KH test statistic with normal bootstrap are shown through simulation to give good performance but are more difficult to implement than the KH test. Two conservative approaches are presented which require only log likelihoods and simple chi-square thresholds. While they did not perform as well as chi-bar and normal bootstrap methods in the simulations considered, they gave better performance than the KH test and have just as simple an implementation. As a by-product of parametric bootstrap considerations, an adjustment to the Swofford-Olsen-Waddell-Hillis (SOWH) test is proposed. © 2014 The Author.
Smith D.R.,University of Western Ontario |
Lee R.W.,Dalhousie University
Plant Physiology | Year: 2014
Polytomella spp. are free-living, nonphotosynthetic green algae closely related to the model organism Chlamydomonas reinhardtii. Although colorless, Polytomella spp. have a plastid, but it is still unknown whether they harbor a plastid genome. We took a next generation sequencing approach, along with transcriptome sequencing, to search for a plastid genome and an associated gene expression system in Polytomella spp. Illumina sequencing of total DNA from four Polytomella spp. did not produce any recognizable plastid-derived reads but did generate a large number of mitochondrial DNA sequences. Transcriptomic analysis of Polytomella parva uncovered hundreds of putative nuclear-encoded, plastid-targeted proteins, which support the presence of plastid-based metabolic functions, similar to those observed in the plastids of other nonphotosynthetic algae. Conspicuously absent, however, were any plastid-targeted proteins involved in the expression, replication, or repair of plastid DNA. Based on these findings and earlier findings, we argue that the Polytomella genus represents the first wellsupported example, to our knowledge, of a primary plastid-bearing lineage without a plastid genome. © 2014 American Society of Plant Biologists. All Rights Reserved.
Parks D.H.,University of Queensland |
Tyson G.W.,University of Queensland |
Hugenholtz P.,University of Queensland |
Beiko R.G.,Dalhousie University
Bioinformatics | Year: 2014
STAMP is a graphical software package that provides statistical hypothesis tests and exploratory plots for analysing taxonomic and functional profiles. It supports tests for comparing pairs of samples or samples organized into two or more treatment groups. Effect sizes and confidence intervals are provided to allow critical assessment of the biological relevancy of test results. A user-friendly graphical interface permits easy exploration of statistical results and generation of publication-quality plots. © The Author 2014. Published by Oxford University Press.
Crosby K.,Dalhousie University |
Smith D.R.,University of British Columbia
PLoS ONE | Year: 2012
Plastid genomes show an impressive array of sizes and compactnesses, but the forces responsible for this variation are unknown. It has been argued that species with small effective genetic population sizes are less efficient at purging excess DNA from their genomes than those with large effective population sizes. If true, one may expect the primary mode of plastid inheritance to influence plastid DNA (ptDNA) architecture. All else being equal, biparentally inherited ptDNAs should have a two-fold greater effective population size than those that are uniparentally inherited, and thus should also be more compact. Here, we explore the relationship between plastid inheritance pattern and ptDNA architecture, and consider the role of phylogeny in shaping our observations. Contrary to our expectations, we found no significant difference in plastid genome size or compactness between ptDNAs that are biparentally inherited relative to those that are uniparentally inherited. However, we also found that there was significant phylogenetic signal for the trait of mode of plastid inheritance. We also found that paternally inherited ptDNAs are significantly smaller (n = 19, p = 0.000001) than those that are maternally, uniparentally (when isogamous), or biparentally inherited. Potential explanations for this observation are discussed. © 2012 Crosby, Smith.
MacLeod A.,Dalhousie University
Academic Medicine | Year: 2011
Purpose: Problem-based learning (PBL) cases tell a story of a medical encounter; however, the version of the story is typically very biomedical in focus. The patient and her or his experience of the situation are rarely the focus of the case despite a prevalent discourse of patient-centeredness in contemporary medical education. This report describes a qualitative study that explored the question, "How does PBL teach medical students about what matters in medicine?" Method: The qualitative study, culminating in 2008, involved three data collection strategies: (1) a discourse analysis of a set of PBL cases from 2005 to 2006, (2) observation of a PBL tutorial group, and (3) semistructured, in-depth, open-ended interviews with medical educators and medical students. Results: In this report, using data gathered from 67 PBL cases, 26 hours of observation, and 14 interviews, the author describes six specific ways in which PBL cases-if not thoughtfully conceptualized and authored-can serve to overlook social considerations, thereby undermining a patient-centered approach. These comprise the detective case, the shape-shifting patient, the voiceless PBL person, the joke name, the disembodied PBL person, and the stereotypical PBL person. Conclusions: PBL cases constitute an important component of undergraduate medical education. Thoughtful authoring of PBL cases has the potential to reinforce, rather than undermine, principles of patient-centeredness. Copyright © by the Association of American Medical Colleges.
Schuelert N.,University of Calgary |
McDougall J.J.,University of Calgary |
McDougall J.J.,Dalhousie University
Arthritis Research and Therapy | Year: 2012
Introduction: A subgroup of voltage gated sodium channels including Nav1.8 are exclusively expressed on small diameter primary afferent neurons and are therefore believed to be integral to the neurotransmission of nociceptive pain. The present study examined whether local application of A-803467, a selective blocker of the Nav 1.8 sodium channel, can reduce nociceptive transmission from the joint in a rodent model of osteoarthritis (OA).Methods: OA-like changes were induced in male Wistar rats by an intra-articular injection of 3 mg sodium monoiodoacetate (MIA). Joint nociception was measured at day 14 by recording electrophysiologically from knee joint primary afferents in response to non-noxious and noxious rotation of the joint both before and following close intra-arterial injection of A-803467. The effect of Nav1.8 blockade on joint pain perception and secondary allodynia were determined in MIA treated animals by hindlimb incapacitance and von Frey hair algesiometry respectively.Results: A-803467 significantly reduced the firing rate of joint afferents during noxious rotation of the joint but had no effect during non-noxious rotation. In the pain studies, peripheral injection of A-803467 into OA knees attenuated hindlimb incapacitance and secondary allodynia.Conclusions: These studies show for the first time that the Nav1.8 sodium channel is part of the molecular machinery involved in mechanotransduction of joint pain. Targeting the Nav1.8 sodium channel on joint nociceptors could therefore be useful for the treatment of OA pain, avoiding the unwanted side effects of non-selective nerve blocks. © 2012 Schuelert et al.; licensee BioMed Central Ltd.
Pearce J.A.,University of Cardiff |
Robinson P.T.,Dalhousie University
Gondwana Research | Year: 2010
Miyashiro (1973) famously initiated a debate on the tectonic setting of ophiolite complexes by proposing that 'the Troodos ophiolitic complex was probably formed in an island arc'. This paper evaluates and updates Miyashiro's work by: (a) using the Mehegan-Robinson set of 137 fresh volcanic glass analyses to sidestep the controversy over the effect of alteration on major element classification diagrams; (b) using the volcanic glass database for Troodos analogues such as back-arc basins, slab edges, forearcs and subduction initiation terranes; (c) revising Miyashiro's classifications by including the boninitic series and subdividing the tholeiitic series into high- and medium-Fe series; and (d) extending Miyashiro's methodologies to new developments in the interpretation of major element data. We conclude that the Troodos Massif is made up of oceanic crust built from a high-Si8, moderate-Fe tholeiitic magma, overlain by boninites. Its low K8/H8 is consistent with near-trench crustal accretion and its Na8-Fe8 systematics indicate that TP = c.1400 °C for the Lower Lavas, consistent with rapid slab roll-back and/or sideways influx of hot mantle. Overall, the geochemical characteristics and geological setting support models in which the Troodos Massif formed by slab roll-back following subduction initiation, probably near a slab edge. © 2009 International Association for Gondwana Research.
Fennel K.,Dalhousie University
Ocean Science | Year: 2010
Continental shelves play a key role in the cycling of nitrogen and carbon. Here the physical transport and biogeochemical transformation processes affecting the fluxes into and out of continental shelf systems are reviewed, and their role in the global cycling of both elements is discussed. Uncertainties in the magnitude of organic and inorganic matter exchange between shelves and the open ocean is a major source of uncertainty in observation-based estimates of nitrogen and carbon fluxes. The shelf-open ocean exchange is hard to quantify based on observations alone, but can be inferred from biogeochemical models. Model-based nitrogen and carbon budgets are presented for the Northwestern North Atlantic continental shelf. Results indicate that shelves are an important sink for fixed nitrogen and a source of alkalinity, but are not much more efficient in exporting organic carbon to the deep ocean than the adjacent open ocean for the shelf region considered. © Author(s) 2010.
Hall B.K.,Dalhousie University
Journal of Applied Ichthyology | Year: 2014
Vertebrates have both more than one skeleton and multiple skeletal systems reflecting origins from two germ layers (mesoderm and neural crest), locations of skeletal elements as external or internal (exo- and endoskeleton), and separate craniofacial, axial and appendicular skeleton systems. Current studies reinforce the exoskeleton as consisting of bone and dentine to the exclusion of cartilage. The endoskeleton is based in cartilage, which, depending on lineage may be replaced by bone. Current understanding of the nature of the exo- and endoskeletons, modes of ossification (intramembranous, endochondral, perichondral), and the contributions of mesodermal and neural crest cells to the skeleton(s) is summarized and then discussed in more depth using fin rays in paired and unpaired fins as examples. Recent studies demonstrating that fin rays and scales are mesodermal and not neural crest in origin are reviewed and whether trunk neural crest cells have skeletogenic potential is considered. These results are discussed in the context of whether scales and fin rays should continue to be regarded as components of the exoskeleton. The conclusion is that they should, thereby separating germ layer of origin from classification of skeletal elements as exo- or endoskeletal; germ layer of origin does not provide unambiguous evidence for classification of elements as parts of the exo- or endoskeletons. Recent studies indicating that turtle shells are mesodermal in origin provides further evidence of the contribution of mesoderm to skeletal elements traditionally regarded as part of the exoskeleton. Therefore, exoskeleton is not synonymous with neural crest origin. These studies on fish fin rays/scales and turtle shells herald a new paradigm in which germ layer of origin (mesoderm or neural crest) does not equate with classification of elements as parts of the endo- or exoskeleton. © 2014 Blackwell Verlag GmbH.
Outram S.M.,Dalhousie University
Journal of Medical Ethics | Year: 2010
During the past few years considerable debate has arisen within academic journals with respect to the use of smart drugs or cognitive enhancement pharmaceuticals. The following paper seeks to examine the foundations of this cognitive enhancement debate using the example of methylphenidate use among college students. The argument taken is that much of the enhancement debate rests upon inflated assumptions about the ability of such drugs to enhance and over-estimations of either the size of the current market for such drugs or the rise in popularity as drugs for enhancing cognitive abilities. This article provides an overview of the empirical evidence that methylphenidate has the ability to significantly improve cognitive abilities in healthy individuals, and examines whether the presumed uptake of the drug is either as socially significant as implied or growing to the extent that it requires urgent regulatory attention. In addition, it reviews the evidence of side-effects for the use of methylphenidate which may be an influential factor in whether an individual decides to use such drugs. The primary conclusions are that neither drug efficacy, nor the benefit-to-risk balance, nor indicators of current or growing demand provide sufficient evidence that methylphenidate is a suitable example of a cognitive enhancer with mass appeal. In light of these empirically based conclusions, the article discusses why methylphenidate might have become seen as a smart drug or cognitive enhancer.
Mackay-Lyons M.,Dalhousie University
The Cochrane database of systematic reviews | Year: 2013
Stroke is the second leading cause of death among adults worldwide. Individuals who have suffered a stroke are at high risk of having another stroke likely leading to greater disability and institutionalization. Non-pharmacological interventions may have a role to play in averting a second stroke. To determine the effectiveness of multi-modal programs of non-pharmacological interventions compared with usual care in preventing secondary vascular events and reducing vascular risk factors after stroke or transient ischemic attack (TIA). We searched the Cochrane Stroke Group Trials Register (September 2012); The Cochrane Library databases CENTRAL, CDSR, DARE, HTA and NHS EED (2012 Issue 2); MEDLINE (1950 to February 2012); EMBASE (1974 to February 2012); CINAHL (1982 to February 2012); SPORTDiscus (1800 to February 2012); PsycINFO (1887 to February 2012) and Web of Science (1900 to February 2012). We also searched PEDro, OT Seeker, OpenSIGLE, REHABDATA and Dissertation Abstracts (February 2012). In an effort to identify further published, unpublished and ongoing trials we searched trials registers, scanned reference lists, and contacted authors and researchers. We included randomized controlled trials evaluating the use of non-pharmacological interventions that included components traditionally used in cardiac rehabilitation (CR) programs in adults with stroke or TIA. Primary outcomes were a cluster of second stroke or myocardial infarction or vascular death. Secondary outcomes were (1) secondary vascular events: second stroke, myocardial infarction, and vascular death, as well as (2) vascular risk factors: blood pressure, body weight, lipid profile, insulin resistance and tobacco use. We also recorded adverse events such as exercise-related musculoskeletal injuries or cardiovascular events. Two review authors independently scanned titles and abstracts and independently screened full reports of studies that were potentially relevant. At each stage, we compared results. The two review authors resolved disagreements through discussion or by involving a third review author. We identified one study, involving 48 participants, of a 10-week CR program for patients post-stroke that met the inclusion criteria. The results of this completed pilot trial show that patients post-stroke had significantly greater improvement in cardiac risk score in the CR group (13.4 ± 10.1 to 12.4 ± 10.5, P value < 0.05) when compared with usual care (9.4 ± 6.7 to 15.0 ± 6.1, P value < 0.05). In addition, five trials, which are ongoing, will likely meet the inclusion criteria for this review once completed. There is limited applicable evidence. Therefore, no implications for practice can be drawn. Further research is required and several trials are underway, the findings of which are anticipated to contribute to the body of evidence.
Martin-Misener R.,Dalhousie University
Nursing leadership (Toronto, Ont.) | Year: 2010
In Canada, education programs for the clinical nurse specialist (CNS) and nurse practitioner (NP) roles began 40 years ago. NP programs are offered in almost all provinces. Education for the CNS role has occurred through graduate nursing programs generically defined as providing preparation for advanced nursing practice. For this paper, we drew on pertinent sections of a scoping review of the literature and key informant interviews conducted for a decision support synthesis on advanced practice nursing to describe the following: (1) history of advanced practice nursing education in Canada, (2) current status of advanced practice nursing education in Canada, (3) curriculum issues, (4) interprofessional education, (5) resources for education and (6) continuing education. Although national frameworks defining advanced nursing practice and NP competencies provide some direction for education programs, Canada does not have countrywide standards of education for either the NP or CNS role. Inconsistency in the educational requirements for primary healthcare NPs continues to cause significant problems and interferes with inter-jurisdictional licensing portability. For both CNSs and NPs, there can be a mismatch between a generalized education and specialized practice. The value of interprofessional education in facilitating effective teamwork is emphasized. Recommendations for future directions for advanced practice nursing education are offered.
Vance J.E.,University of Alberta |
Karten B.,Dalhousie University
Journal of Lipid Research | Year: 2014
Niemann-Pick type C (NPC) disease is a lysosomal storage disease in which endocytosed cholesterol becomes sequestered in late endosomes/lysosomes (LEs/Ls) because of mutations in either the NPC1 or NPC2 gene. Mutations in either of these genes can lead to impaired functions of the NPC1 or NPC2 proteins and progressive neurodegeneration as well as liver and lung disease. NPC1 is a polytopic protein of the LE/L limiting membrane, whereas NPC2 is a soluble protein in the LE/L lumen. These two proteins act in tandem and promote the export of cholesterol from LEs/Ls. Consequently, a defect in either NPC1 or NPC2 causes cholesterol accumulation in LEs/Ls. In this review, we summarize the molecular mechanisms leading to NPC disease, particularly in the CNS. Recent exciting data on the mechanism by which the cholesterol-sequestering agent cyclodextrin can bypass the functions of NPC1 and NPC2 in the LEs/Ls, and mobilize cholesterol from LEs/Ls, will be highlighted. Moreover, the possible use of cyclodextrin as a valuable therapeutic agent for treatment of NPC patients will be considered. Copyright © 2014 by the American Society for Biochemistry and Molecular Biology, Inc.
Linsdell P.,Dalhousie University
Molecular Membrane Biology | Year: 2014
Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), a member of the ATP-binding cassette (ABC) family of membrane transport proteins. CFTR is unique among ABC proteins in that it functions not as an active transporter but as an ATP-gated Cl- channel. As an ion channel, the function of the CFTR transmembrane channel pore that mediates Cl- movement has been studied in great detail. On the other hand, only low resolution structural data is available on the transmembrane parts of the protein. The structure of the channel pore has, however, been modeled on the known structure of active transporter ABC proteins. Currently, significant barriers exist to building a unified view of CFTR pore structure and function. Reconciling functional data on the channel with indirect structural data based on other proteins with very different transport functions and substrates has proven problematic. This review summarizes current structural and functional models of the CFTR Cl- channel pore, including a comprehensive review of previous electrophysiological investigations of channel structure and function. In addition, functional data on the three-dimensional arrangement of pore-lining helices, as well as contemporary hypotheses concerning conformational changes in the pore that occur during channel opening and closing, are discussed. Important similarities and differences between different models of the pore highlight current gaps in our knowledge of CFTR structure and function. In order to fill these gaps, structural and functional models of the membrane-spanning pore need to become better integrated. © 2014 Informa UK Ltd.
Anderson T.R.,University of Southampton |
Gentleman W.C.,Dalhousie University |
Sinha B.,University of Southampton
Progress in Oceanography | Year: 2010
Sensitivity to nonlinear equations may be a characteristic feature of biological models, particularly those that are complex. A complex marine ecosystem model (PlankTOM5.2) that incorporates multiple plankton functional types (PFTs) was embedded in a global ocean general circulation model (OGCM) and its performance assessed for four different formulations of multiple-prey zooplankton functional response: Michaelis-Menten (MM: Holling Type II), Sigmoidal (S: Holling Type III), Blackman (B) and Ivlev (Iv). Predictions of the four simulations were compared for the North Atlantic and North Pacific oceans. Remarkable differences were seen in both spatial extent and magnitude of predicted distributions of PFTs, as well as bulk properties, highlighting how the choice of functional response has a major impact on the resulting ecosystem structure. The range of average concentration of diatoms in surface waters was particularly marked, varying between 0.04mgm -3 (B and MM) and 0.13mgm -3 (S) in spring and between 0.01mgm -3 (B) and 0.07mgm -3 (S) in autumn. Differences in ecosystem structure affected predicted export flux, which varied by more than 25% among the simulations. Overall, our work highlights that accuracy is required in ecosystem formulation if reliable predictions are to be made when using complex marine ecosystem models embedded in OGCMs and therefore the need for further studies, with appropriate validation, that address structural sensitivity. © 2010 Elsevier Ltd.
Moors-Murphy H.B.,Dalhousie University
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2014
There has been much research interest in the use of submarine canyons by cetaceans, particularly beaked whales (family Ziphiidae), which appear to be especially attracted to canyon habitats in some areas. However, not all submarine canyons are associated with large numbers of cetaceans and the mechanisms through which submarine canyons may attract cetaceans are not clearly understood. This paper reviews some of the cetacean associations with submarine canyons that have been anecdotally described or presented in scientific literature and discusses the physical, oceanographic and biological mechanisms that may lead to enhanced cetacean abundance around these canyons. Particular attention is paid to the Gully, a large submarine canyon and Marine Protected Area off eastern Canada for which there exists some of the strongest evidence available for submarine canyons as important cetacean habitat. Studies demonstrating increased cetacean abundance in the Gully and the processes that are likely to attract cetaceans to this relatively well-studied canyon are discussed. This review provides some limited evidence that cetaceans are more likely to associate with larger canyons; however, further studies are needed to fully understand the relationship between the physical characteristics of canyons and enhanced cetacean abundance. In general, toothed whales (especially beaked whales and sperm whales) appear to exhibit the strongest associations with submarine canyons, occurring in these features throughout the year and likely attracted by concentrating and aggregating processes. By contrast, baleen whales tend to occur in canyons seasonally and are most likely attracted to canyons by enrichment and concentrating processes. Existing evidence thus suggests that at least some submarine canyons are important foraging areas for cetaceans, and should be given special consideration for cetacean conservation and protection. © 2013 Elsevier Ltd.
Huang J.,Colorado School of Mines |
Griffiths D.V.,Colorado School of Mines |
Fenton G.A.,Dalhousie University
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2010
Coupled Biot consolidation theory was combined with the random finite-element method to investigate the consolidation behavior of soil deposits with spatially variable properties in one-dimensional (1D) and two-dimensional (2D) spaces. The coefficient of volume compressibility (mv) and the soil permeability (k) are assumed to be lognormally distributed random variables. The random fields of mv and k are generated by the local average subdivision method which fully takes account of spatial correlation, local averaging, and cross correlations. The generated random variables are mapped onto a finite-element mesh and Monte Carlo finite-element simulations follow. The results of parametric studies are presented, which describe the effect of the standard deviation, spatial correlation length, and cross correlation coefficient on output statistics relating to the overall "equivalent" coefficient of consolidation. It is shown that the average degree of consolidation defined by excess pore pressure and settlement are different in heterogeneous soils. The dimensional effect on the soil consolidation behaviors is also investigated by comparing the 1D and 2D results. © 2010 ASCE.
Mitnitski A.,Dalhousie University |
Rockwood K.,Health Science Center
Biogerontology | Year: 2016
People age at different rates. We have proposed that rates of aging can be quantified by the rate at which individuals accumulate health deficits. Earlier estimates, using cross-sectional analyses suggested that deficits accumulated exponentially, at an annual rate of 3.5 %. Here, we estimate the rate of deficit accumulation using longitudinal data from the Canadian National Population Health Survey. By analyzing age-specific trajectories of deficit accumulation in people aged 20 years and over (n = 13,668) followed biannually for 16 years, we found that the longitudinal average annual rate of deficit accumulation was 4.5 % (±0.75 %). This estimate was notably stable during the adult life span. The corresponding average doubling time in the number of deficits was 15.4 (95 % CI 14.82–16.03) years, roughly 30 % less than we had reported from the cross-sectional analysis. Earlier work also established that the average number of deficits accumulated by individuals (N), equals the product of the intensity of environmental stresses (λ) causing damage to the organism, by the average recovery time (W). At the individual level, changes in deficit accumulation can be attributed to both changes in environmental stresses and changes in recovery time. By contrast, at the population level, changes in the number of deficits are proportional to the changes in recovery time. In consequence, we propose here that the average recovery time, W doubles approximately every 15.4 years, independently of age. Such changes quantify the increase of vulnerability to stressors as people age that gives rise to increasing risk of frailty, disability and death. That deficit accumulation will, on average, double twice between ages 50 and 80 highlights the importance of health in middle age on late life outcomes. © 2015, Springer Science+Business Media Dordrecht.
Stone S.L.,Dalhousie University
Frontiers in Plant Science | Year: 2014
Ubiquitin is a small, highly conserved, ubiquitously expressed eukaryotic protein with immensely important and diverse regulatory functions. A well-studied function of ubiquitin is its role in selective proteolysis by the ubiquitin-proteasome system (UPS). The UPS has emerged as an integral player in plant response and adaptation to environmental stresses such as drought, salinity, cold and nutrient deprivation. The UPS has also been shown to influence the production and signal transduction of stress-related hormones such as abscisic acid. Understanding UPS function has centered mainly on defining the role of E3 ubiquitin ligases, which are the substrate-recruiting component of the ubiquitination pathway.The recent identification of stress signaling/regulatory proteins that are the subject of ubiquitin-dependent degradation has increased our knowledge of how the UPS facilitates responses to adverse environmental conditions. A brief overview is provided on role of the UPS in modulating protein stability during abiotic stress signaling. E3 ubiquitin ligases for which stress-related substrate proteins have been identified are discussed. © 2014 Stone.
McNeil M.L.,Dalhousie University
Journal of otolaryngology - head & neck surgery = Le Journal d'oto-rhino-laryngologie et de chirurgie cervico-faciale | Year: 2013
Otoplasty is a commonly performed surgical procedure that restores the ideal position of the pinna. Although the pinna is a well-recognized component of the auditory apparatus, no studies have assessed the audiological effects of this procedure. We sought to quantify the impact of pinna repositioning on speech intelligibility and reception. Eighteen adults with normal hearing and pinnae were recruited and the pinna positions were randomized in each participant. Intracanal acoustical analysis was performed to calculate the Speech Intelligibility Index (SII). Hearing In Noise Test (HINT) with two azimuth speaker arrangement was also performed. The outcome measures were compared using paired t-tests for both pinna positions. The SII significantly improved with the pinna in forward position (49.3 vs. 45.8, p<0.001). HINT thresholds also improved with the pinna forward (-6.43 dB vs. -5.08 dB, p=0.0003). Pinna position affects audiological performance, in both speech intelligibility and speech reception in noise. These are novel findings that may impact the informed consent process and decision to treat for patients undergoing otoplasty.
Law J.A.,Dalhousie University
Canadian Journal of Anesthesia | Year: 2013
Background: Previously active in the mid-1990s, the Canadian Airway Focus Group (CAFG) studied the unanticipated difficult airway and made recommendations on management in a 1998 publication. The CAFG has since reconvened to examine more recent scientific literature on airway management. The Focus Group's mandate for this article was to arrive at updated practice recommendations for management of the unconscious/induced patient in whom difficult or failed tracheal intubation is encountered. Methods: Nineteen clinicians with backgrounds in anesthesia, emergency medicine, and intensive care joined this iteration of the CAFG. Each member was assigned topics and conducted reviews of Medline, EMBASE, and Cochrane databases. Results were presented and discussed during multiple teleconferences and two face-to-face meetings. When appropriate, evidence- or consensus-based recommendations were made together with assigned levels of evidence modelled after previously published criteria. Conclusions: The clinician must be aware of the potential for harm to the patient that can occur with multiple attempts at tracheal intubation. This likelihood can be minimized by moving early from an unsuccessful primary intubation technique to an alternative Plan B technique if oxygenation by face mask or ventilation using a supraglottic device is non-problematic. Irrespective of the technique(s) used, failure to achieve successful tracheal intubation in a maximum of three attempts defines failed tracheal intubation and signals the need to engage an exit strategy. Failure to oxygenate by face mask or supraglottic device ventilation occurring in conjunction with failed tracheal intubation defines a failed oxygenation, cannot intubate, cannot oxygenate situation. Cricothyrotomy must then be undertaken without delay, although if not already tried, an expedited and concurrent attempt can be made to place a supraglottic device. © 2013 The Author(s).
Law J.A.,Dalhousie University
Canadian Journal of Anesthesia | Year: 2013
Background: Appropriate planning is crucial to avoid morbidity and mortality when difficulty is anticipated with airway management. Many guidelines developed by national societies have focused on management of difficulty encountered in the unconscious patient; however, little guidance appears in the literature on how best to approach the patient with an anticipated difficult airway. Methods: To review this and other subjects, the Canadian Airway Focus Group (CAFG) was re-formed. With representation from anesthesiology, emergency medicine, and critical care, CAFG members were assigned topics for review. As literature reviews were completed, results were presented and discussed during teleconferences and two face-to-face meetings. When appropriate, evidence- or consensus-based recommendations were made, and levels of evidence were assigned. Principal findings: Previously published predictors of difficult direct laryngoscopy are widely known. More recent studies report predictors of difficult face mask ventilation, video laryngoscopy, use of a supraglottic device, and cricothyrotomy. All are important facets of a complete airway evaluation and must be considered when difficulty is anticipated with airway management. Many studies now document the increasing patient morbidity that occurs with multiple attempts at tracheal intubation. Therefore, when difficulty is anticipated, tracheal intubation after induction of general anesthesia should be considered only when success with the chosen device(s) can be predicted in a maximum of three attempts. Concomitant predicted difficulty using oxygenation by face mask or supraglottic device ventilation as a fallback makes an awake approach advisable. Contextual issues, such as patient cooperation, availability of additional skilled help, and the clinician's experience, must also be considered in deciding the appropriate strategy. Conclusions: With an appropriate airway evaluation and consideration of relevant contextual issues, a rational decision can be made on whether an awake approach to tracheal intubation will maximize patient safety or if airway management can safely proceed after induction of general anesthesia. With predicted difficulty, close attention should be paid to details of implementing the chosen approach. This should include having a plan in case of the failure of tracheal intubation or patient oxygenation. © 2013 The Author(s).
Udenigwe C.C.,Dalhousie University
Trends in Food Science and Technology | Year: 2014
There has been heightened effort to discover bioactive peptides from food and uncover their human health benefits based on preclinical evaluation systems. Consequently, a myriad of bioactive peptides are continuously reported with emerging interest in elucidating structure-function and molecular mechanisms. However, there is limited clinical evidence to substantiate bioactivity and minimal emphasis on translation into functional peptide products for health uses. This paper highlights the prospects of bioinformatics and a proposed integrated approach for enhancing the production of existing and new bioactive peptides from sustainable food protein sources, followed by discussion of the major challenges that may impact prospective commercialization of food bioactive peptides for use in human health promotion. © 2014 Elsevier Ltd.
Cullen J.J.,Dalhousie University
Annual Review of Marine Science | Year: 2015
The phenomenon of subsurface chlorophyll maximum layers (SCMLs) is not a unique ecological response to environmental conditions; rather, a broad range of interacting processes can contribute to the formation of persistent layers of elevated chlorophyll a concentration (Chl) that are nearly ubiquitous in stratified surface waters. Mechanisms that contribute to the formation and maintenance of the SCMLs include a local maximum in phytoplankton growth rate near the nutricline, photoacclimation of pigment content that leads to elevated Chl relative to phytoplankton biomass at depth, and a range of physiologically influenced swimming behaviors in motile phytoplankton and buoyancy control in diatoms and cyanobacteria that can lead to aggregations of phytoplankton in layers, subject to grazing and physical control. A postulated typical stable water structure characterizes consistent patterns in vertical profiles of Chl, phytoplankton biomass, nutrients, and light across a trophic gradient structured by the vertical flux of nutrients and characterized by the average daily irradiance at the nutricline. Hypothetical predictions can be tested using a nascent biogeochemical global ocean observing system. Partial results to date are generally consistent with predictions based on current knowledge, which has strong roots in research from the twentieth century. Copyright © 2015 by Annual Reviews. All rights reserved.
Susko E.,Dalhousie University
Molecular Biology and Evolution | Year: 2010
The most frequent measure of phylogenetic uncertainty for splits is bootstrap support. Although large bootstrap support intuitively suggests that a split in a tree is well supported, it has not been clear how large bootstrap support needs to be to conclude that there is significant evidence that a hypothesized split is present. Indeed, recent work has shown that bootstrap support is not first-order correct and thus cannot be directly used for hypothesis testing. We present methods that adjust bootstrap support values in a maximum likelihood (ML) setting so that they have an interpretation corresponding to P values in conventional hypothesis testing; for instance, adjusted bootstrap support larger than 95% occurs only 5% of the time if the split is not present. Through examples and simulation settings, it is found that adjustments always increase the level of support. We also find that the nature of the adjustment is fairly constant across parameter settings. Finally, we consider adjustments that take into account the data-dependent nature of many hypotheses about splits: the hypothesis that they are present is being tested because they are in the tree estimated through ML. Here, in contrast, we find that bootstrap probability often needs to be adjusted downwards. © The Author 2010.
Fedortchouk Y.,Dalhousie University
Contributions to Mineralogy and Petrology | Year: 2015
The study develops a new approach utilizing parameters of trigonal etch pits on diamond crystals to infer the conditions of diamond residence in kimberlite magma. Diamond crystals from dissolution experiments conducted at 1 GPa and 1150–1350 °C in the presence of H2O-rich or CO2-rich fluid were studied with atomic force microscopy (AFM). The AFM data of resorbed diamond surfaces show that much deeper surface relief was produced in CO2 fluid. It also clearly distinguishes the profiles of the trigonal etch pits forming regular flat-bottomed trigons in H2O fluid, and round- or pointed-bottomed trigons in CO2 fluid. The relationship between the diameter and the depth of the trigonal pits is found to be another important indicator of the fluid composition. Dissolution in H2O fluid develops trigons with constant diameter and variable depth where the diameter increases with temperature. Trigons developed in CO2 fluid have a large range of diameters showing a strong positive correlation with the depth. The developed criteria applied to the natural diamond crystals from three Ekati Mine kimberlites indicate significant variation in CO2–H2O ratio and temperature of their magmatic fluid. This conclusion based on diamond resorption agrees with the mineralogy of microphenocrysts and groundmass of the studied kimberlites offering new method to study crystallization conditions of kimberlite magma. © 2015, Springer-Verlag Berlin Heidelberg.
Turner C.,Dalhousie University |
Kohandel M.,University of Waterloo |
Kohandel M.,Fields Institute
Seminars in Cancer Biology | Year: 2012
The last decade has witnessed significant advances in the application of mathematical and computational models to biological systems, especially to cancer biology. Here, we present stochastic and deterministic models describing tumour growth based on the cancer stem cell hypothesis, and discuss the application of these models to the epithelial-mesenchymal transition. In particular, we discuss how such quantitative approaches can be used to validate different possible scenarios that can lead to an increase in stem cell activity following induction of epithelial-mesenchymal transition, observed in recent experimental studies on human breast cancer and related cell lines. The utility of comparing mammosphere data to computational mammosphere simulations in elucidating the growth characteristics of mammary (cancer) stem cells is discussed as well. © 2012 Elsevier Ltd.
Webster W.G.,Dalhousie University
Journal of Interprofessional Care | Year: 2013
A bottom-up and menu-based approach to embedding interprofessional education (IPE) into the curricula of more than 20 health profession programs at Dalhousie University is described. In addition to adopting an IPE graduation requirement and a common time for IPE activities, progress appears to have been facilitated by placing responsibility directly with the schools that own the curricula rather than with a central office for IPE. © 2013 Informa UK, Ltd.
Herder M.,Dalhousie University
McGill Journal of Law and Health | Year: 2015
In the arena of pharmaceutical drug regulation, transparency is the favoured focus of many current policy initiatives. Transparency is predominantly understood in terms of information disclosure. Requirements to register clinical trials, publish summary results, share clinical trial data, and disclose physician-industry relationships as well as rationales behind regulatory decision making are each predicated upon this idea that imparting information will both inform and deter unwanted behaviours. In this paper, I argue that understanding transparency qua disclosure has clear limitations and suggest transparency can and should serve an additional function – namely, of enabling standard setting through a more participatory, public model of drug regulation. I turn to the history of Canadian drug regulation to demonstrate that such an alternative conception of transparency – transparency qua standard construction – is in fact possible. I document the regulator’s extensive use of publicity practices to develop standards for assessing drug adulteration through the early years of Canadian drug regulation, from 1887 to 1920 when hundreds of analytical bulletins were publicly disseminated. I also show how, from the 1920s onwards, this participatory, public transparency transmogrified into a form of closed, insider transparency as the regulator constituted a collaborative relationship with industry. Given this shift, I suggest that an alternative conception of transparency is not only possible but also increasingly needed, and then begin to sketch how tying transparency to a revitalized concept of fraud in drug research and development might activate that participatory, public regulatory work. © Matthew Herder 2015.
Scheibling R.E.,Dalhousie University |
Lauzon-Guay J.-S.,Maurice Lamontagne Institute
Limnology and Oceanography | Year: 2010
An increase in the incidence of disease in various marine organisms over the past few decades has been linked to ocean climate change. In Nova Scotia, Canada, mass mortalities of sea urchins, due to an amoebic disease, are associated with tropical cyclones of relatively high intensity that pass close to the coast when water temperature is above a threshold for disease propagation. These conditions increase the likelihood of introduction and spread of a nonindigenous water-borne pathogen through turbulent mixing. Our analysis shows that the most deadly storms, in terms of the probability of a sea urchin mass mortality, have become more deadly over the past 30 years. We also found that storms have been tracking closer to the coast and that surface temperature has increased during the hurricane season. These trends are likely to continue with climate warming, resulting in a regional shift to a kelp bed ecosystem and the loss of the urchin fishery. © 2010, by the American Society of Limnology and Oceanography, Inc.
Shea S.E.,Dalhousie University
Pediatrics in Review | Year: 2012
• Clinicians should consider replacing their use of the term mental retardation with intellectual disability (ID). • A careful history and physical examination remain the most helpful tools for determining the cause of a child's ID. • Genetic testing may reveal the etiology of ID in at least 14% of children with nondiagnostic histories and physical examinations. • Individuals who have ID are at risk for poorer health outcomes. • Transitions are points of particular vulnerability for persons who have ID and their families.
Coxon J.A.,Dalhousie University |
Hajigeorgiou P.G.,University of Nicosia
Journal of Chemical Physics | Year: 2010
A collection of 16 544 fluorescence series spectroscopic line positions involving the A 1 ∑u + →X 1 ∑g + transition in Cs2 has been analyzed by a modern direct potential fitting procedure to generate the first fully analytical potential energy function for the ground electronic state, and precise energy term values for the excited A 1 ∑u + state. The potential function yields an accurate representation of spectroscopic data that span 99.24% of the well depth and the number of fitted parameters is significantly less than half the number of parameters determined in conventional Dunham analyses. A novel variant of the Morse/long-range potential model has been employed in the representation of the ground state potential, and a critical comparison has been made with an extended modified Lennard-Jones potential model. Proper account has been taken of the known long-range van der Waals form of the potential, and our final potential function is determined with constrained literature values of the C8 and C10 dispersion energy coefficients, along with a fitted value of C6 =3.31 (5) × 107 cm-1 Å6 =6870(100) a.u. The fitted dissociation energy (De) is compared with the precisely known value based on the recent analysis of data from a two-photon transfer process (STIRAP) in ultracold Cs atoms. It is concluded that hyperfine effects in the X1 ∑g + state are not negligible, and that the estimate of De =3649.84 (7) cm-1 obtained in this work represents an effective dissociation limit lying between the two lowest hyperfine limits. Precise rotational and centrifugal distortion constants for the ground electronic state have also been calculated through conventional perturbation theory. These estimates are fully consistent with the derived potential function and the experimental spectroscopic information. © 2010 American Institute of Physics.
Beiko R.G.,Dalhousie University
Trends in Microbiology | Year: 2015
The names and lineages of microorganisms are critical to our understanding of the microbiome. However, microbial taxonomy and phylogeny are in perpetual flux, with emerging criteria being used to rename and reshape our views of the microbial world. Different candidate molecular and nonmolecular criteria are often broadly consistent with one another, which underpins the pluralistic approach to taxonomy. However, the taxonomic picture is clouded when underlying criteria are not in agreement, or when reference datasets contain erroneously named organisms. How does the shifting taxonomic landscape impact our interpretation of microbial communities, especially in the face of inconsistencies and errors? How can taxonomy be applied in a consistent way when different users have different requirements of the classifications that emerge? The key path forward involves finding ways to integrate conflicting taxonomic criteria, choosing the right units of analysis for microbiomic studies, and making molecular taxonomy transparent and accessible in a way that complements current genomic resources. © 2015 Elsevier Ltd.
Pinsky M.L.,Stanford University |
Jensen O.P.,Rutgers University |
Ricard D.,Dalhousie University |
Palumbi S.R.,Stanford University
Proceedings of the National Academy of Sciences of the United States of America | Year: 2011
Understanding which species are most vulnerable to human impacts is a prerequisite for designing effective conservation strategies. Surveys of terrestrial species have suggested that largebodied species and top predators are the most at risk, and it is commonly assumed that such patterns also apply in the ocean. However, there has been no global test of this hypothesis in the sea. We analyzed two fisheries datasets (stock assessments and landings) to determine the life-history traits of species that have suffered dramatic population collapses. Contrary to expectations, our data suggest that up to twice as many fisheries for small, low trophic-level species have collapsed compared with those for large predators. These patterns contrast with those on land, suggesting fundamental differences in the ways that industrial fisheries and land conversion affect natural communities. Even temporary collapses of small, low trophic-level fishes can have ecosystem-wide impacts by reducing food supply to larger fish, seabirds, and marine mammals.
Currie C.A.,University of Alberta |
Beaumont C.,Dalhousie University
Earth and Planetary Science Letters | Year: 2011
Diamond-bearing Cretaceous kimberlites of western North America were emplaced 1000-1500 km inboard of the Farallon plate subduction margin and overlap with the development of the Western Interior Seaway, shut-down of the Sierra Nevada arc, and the Laramide orogeny. These events are consistent with a decrease in subduction angle along much of the margin, which placed the subducted Farallon plate in close proximity to the continental interior at the time of kimberlite magmatism. Our numerical models demonstrate that low-angle subduction can result from high plate convergence velocities and enhanced westward motion of North America. Further, rapid subduction allows hydrous minerals to remain stable within the cool interior of the subducting plate to more than 1200 km from the trench. Destabilization of these minerals provides a fluid source that can infiltrate the overlying material, potentially triggering partial melting and kimberlite/lamproite magmatism. © 2010 Elsevier B.V.
Selinger P.,Dalhousie University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013
We give a Clifford+T representation of the Toffoli gate of T-depth one, using four ancillas. More generally, we describe a class of circuits whose T-depth can be reduced to one by using sufficiently many ancillas. We show that the cost of adding an additional control to any controlled gate is at most eight additional T gates and T-depth two. We also show that the circuit THT does not possess a T-depth one representation with an arbitrary number of ancillas initialized to |0âŒ. © 2013 American Physical Society.
Adamo S.A.,Dalhousie University
Hormones and Behavior | Year: 2012
This article is part of a Special Issue "Neuroendocrine-Immune Axis in Health and Disease." Stress-induced changes in immune function occur in animals across phyla, and these effects are usually immunosuppressive. The function of this immunomodulation remains elusive; however, the existence of specialized receptors on immune cells suggests that it is adaptive. A comparative approach may provide a useful perspective. Although invertebrates have simpler endocrine/neuroendocrine systems and immune systems than vertebrates, they have robust stress responses that include the release of stress hormones/neurohormones. Stress hormones modify immune function in mollusks, insects, and crustaceans. As in vertebrates, the effects of stress hormones/neurohormones on invertebrate immune function are complex, and are not always immunosuppressive. They are context-, stressor-, time- and concentration-dependent. Stress hormone effects on invertebrate immune function may help to re-align resources during fight-or-flight behavior. The data are consistent with the hypothesis that stress hormones induce a reconfiguration of networks at molecular, cellular and physiological levels that allow the animal to maintain optimal immunity as the internal environment changes. This reconfiguration enhances some immune functions while suppressing others. Knowing the molecular details of these shifts will be critical for understanding the adaptive function of stress hormones on immune function. © 2012 Elsevier Inc.
Sligl W.I.,University of Alberta |
Marrie T.J.,Dalhousie University
Critical Care Clinics | Year: 2013
Severe community-acquired pneumonia necessitating intensive care unit admission is associated with high morbidity, mortality, and health-care cost. This review article serves to summarize the epidemiology, diagnosis, treatment, and prognosis of this common life-threatening condition. Current practice guidelines as well as the role of several scoring systems (such as the PSI, CURB-65, and IDSA/ATS criteria) used to predict CAP severity, prognosis, and site of care are reviewed. In addition, common complications and prevention strategies are discussed. © 2013 Elsevier Inc.
Rockwood K.,Dalhousie University
International Journal of Alzheimer's Disease | Year: 2011
It is often surprisingly difficult to tell whether a treatment for Alzheimer's disease is effective. Biomarkers might offer the potential of a quantifiable objective measure of treatment effectiveness. This paper suggests several criteria by which biomarkers might be evaluated as outcomes measures. These include biological plausibility, statistical significance, dose dependence, convergence across measures, and replicability. If biomarkers can meet these criteria, then, pending regulatory approval, they may have a role in the evaluation of treatment effectiveness in Alzheimer's disease. If not, their usefulness may be in supplementing, but not supplanting, clinical profiles of treatment effects. Copyright © 2011 Kenneth Rockwood.
Martin F.S.,Dalhousie University
Addiction Research and Theory | Year: 2010
This article engages in a sociological analysis of young women's experiences of initiation; its aim is to complement epidemiological research on women injectors' relative vulnerability to drug-related risk through an exploration of the social conditions in which this increased vulnerability is produced. This article is based on the findings of qualitative research indicating that young women's initiation to injecting drug use often takes place in the context of intimate relationships. The analysis presented explores the social and personal significance of intimate relationships in young women's lives, and the link between risk-taking and intimacy. © 2010 Informa UK Ltd All rights reserved.
Whitehead H.,Dalhousie University
Current Biology | Year: 2015
Menopause evolved in humans and whales, presumably because older females can help their kin. But how do they help? New research shows that post-menopausal female killer whales lead foraging groups. This leadership is most significant when food is scarce. © 2015 Elsevier Ltd All rights reserved.
Steinbring E.,National Research Council Canada |
Ward W.,University of New Brunswick |
Drummond J.R.,Dalhousie University
Publications of the Astronomical Society of the Pacific | Year: 2012
Nighttime visible-light sky brightness and transparency are reported for the Polar Environment Research Laboratory (PEARL), located on a 610 m high ridge near the Eureka research station at 80° latitude, on Ellesmere Island, Canada. Photometry of Polaris obtained in the V band with the PEARL All Sky Imager (PASI) over two winters is supported by standard meteorological measurements and visual estimates of sky conditions from sea level. These data show that during the period of the study, 2008/2009 and 2009/2010 October through March, the sky near zenith had a mean surface brightness of 19:7 mag arcsec -2 when the Sun was more than 12° below the horizon, reaching 20:7 mag arcsec -2 during astronomical darkness with no Moon. Skies were without thick cloud and potentially usable for astronomy 86% of the time (extinction <2 mag). Up to 68% of the time was spectroscopic (≤0:5 mag), attenuated by ice crystals, or clear with stable atmospheric transparency. Those conditions can persist for over 100 hr at a time. Further analysis suggests the sky was entirely free of ice crystals (truly photometric) 48 ± 3% of the time at PEARL in winter and that a higher elevation location nearby may be better. © 2012. The Astronomical Society of the Pacific.
Bielawski J.P.,Dalhousie University
Current Protocols in Molecular Biology | Year: 2013
The field of molecular evolution, which includes genome evolution, is devoted to finding variation within and between groups of organisms and explaining the processes responsible for generating this variation. Many DNA changes are believed to have little to no functional effect, and a neutral process will best explain their evolution. Thus, a central task is to discover which changes had positive fitness consequences and were subject to Darwinian natural selection during the course of evolution. Due the size and complexity of modern molecular datasets, the field has come to rely extensively on statistical modeling techniques to meet this analytical challenge. For DNA sequences that encode proteins, one of the most powerful approaches is to employ a statistical model of codon evolution. This unit provides a general introduction to the practice of modeling codon evolution using the statistical framework of maximum likelihood. Four real-data analysis activities are used to illustrate the principles of parameter estimation, robustness, hypothesis testing, and site classification. Each activity includes an explicit analytical protocol based on programs provided by the Phylogenetic Analysis by Maximum Likelihood (PAML) package. © 2013 by John Wiley & Sons, Inc.
Cohen M.M.,Dalhousie University
American Journal of Medical Genetics, Part A | Year: 2013
AKT (AK mouse plus Transforming or Thymoma) is a common oncogene expressed in most tissues. Both AKT2 and AKT3, although important, have more limited distributions. The regulation of all three genes depends on two receptors-a receptor tyrosine kinase with a growth factor ligand, and a G protein coupled receptor, also with a ligand together with an explanation of how their downsteam components function. AKT2 is amplified or overexpressed in cancer with a higher frequency than those found with AKT1. AKT1 is cardioprotective to the heart by supporting its physiological growth and function. AKT2 is closely linked to Type II diabetes and the implications of various types of mutations are discussed. Various AKT3 mutations are important in neurological disorders, such as microcephaly, hemimegalencephaly, and megalencephaly syndromes. Finally, a reduced level of AKT1 in the frontal cortex has been found during post-mortem brain studies of schizophrenic patients in the populations of many countries. © 2013 Wiley Periodicals, Inc.
Purdy R.A.,Dalhousie University
Neurological Sciences | Year: 2011
The visual system plays a prominent role in migraine headache, especially migraine with aura. Anatomical and functional studies in migraine are showing an increasing role linking the visual system to migraine and its multiple and complex clinical expressions. Recent research on photophobia highlights the progress of our understanding of these relationships. This review overviews a practicing neurologist's view of some of the roles of the visual system in migraine and how a clinical understanding of this relationship is enhanced by recent research and discovery in this in this important area. © Springer-Verlag 2011.
Yoshino T.,Okayama University |
Laumonier M.,CNRS Earth Sciences Institute of Orleans |
McIsaac E.,Dalhousie University |
Katsura T.,Okayama University
Earth and Planetary Science Letters | Year: 2010
Electrical impedance measurements were performed on two types of partial molten samples with basaltic and carbonatitic melts in a Kawai-type multi-anvil apparatus in order to investigate melt fraction-conductivity relationships and melt distribution of the partial molten mantle peridotite under high pressure. The silicate samples were composed of San Carlos olivine with various amounts of mid-ocean ridge basalt (MORB), and the carbonate samples were a mixture of San Carlos olivine with various amounts of carbonatite. High-pressure experiments on the silicate and carbonate systems were performed up to 1600K at 1.5GPa and up to at least 1650K at 3GPa, respectively. The sample conductivity increased with increasing melt fraction. Carbonatite-bearing samples show approximately one order of magnitude higher conductivity than basalt-bearing ones at the similar melt fraction. A linear relationship between log conductivity (σbulk) and log melt fraction (Φ) can be expressed well by the Archie's law (Archie, 1942) (σbulk/σmelt=CΦn) with parameters C=0.68 and 0.97, n=0.87 and 1.13 for silicate and carbonate systems, respectively. Comparison of the electrical conductivity data with theoretical predictions for melt distribution indicates that the model assuming that the grain boundary is completely wetted by melt is the most preferable melt geometry. The gradual change of conductivity with melt fraction suggests no permeability jump due to melt percolation at a certain melt fraction. The melt fraction of the partial molten region in the upper mantle can be estimated to be 1-3% and ~0.3% for basaltic melt and carbonatite melt, respectively. © 2010 Elsevier B.V.
Mayerhofer M.S.,Saint Marys University, Halifax |
Kernaghan G.,Mount Saint Vincent University |
Harper K.A.,Dalhousie University
Mycorrhiza | Year: 2013
Fungal root endophytes are plant associates that colonize root tissue internally without causing any obvious harm to their host. Although ubiquitous, this relationship is not well understood. Our objectives were to determine the effects of fungal root endophyte inoculation on plant biomass and nitrogen concentration by conducting an extensive meta-analysis. We also explored the effects of experimental conditions on the host-endophyte relationship. We performed analyses weighted with non-parametric variance on plant response to root endophytes from the Ascomycetes (excluding the Clavacipitaceae), including categorical analyses of 21 experimental factors, ranging from the identity of the host and the endophyte, to the composition of the growing medium. The response of total biomass to endophyte inoculation was 18 % lower than non-inoculated controls, while individually, root biomass, shoot biomass, and nitrogen concentration responses to endophyte inoculation were neutral. The identities of both the host and the endophyte had an influence, as did the original source of the endophyte (whether or not the isolate used originated from the same host species). Experimental conditions also influenced the plant-endophyte relationship, with the most important being the availability and sources of carbon and organic nitrogen, particularly peat moss. Although our analysis demonstrates that overall plant biomass and nitrogen concentration responses to ascomycetous root endophyte inoculation is neutral to negative, these results are somewhat confounded by among-study differences in experimental conditions, which undoubtedly contribute to the high levels of variability in plant response seen in the literature. © 2012 Springer-Verlag.
Mann K.V.,Dalhousie University
Medical Education | Year: 2011
Context Pedagogical practices reflect theoretical perspectives and beliefs that people hold about learning. Perspectives on learning are important because they influence almost all decisions about curriculum, teaching and assessment. Since Flexner's 1910 report on medical education, significant changes in perspective have been evident. Yet calls for major reform of medical education may require a broader conceptualisation of the educational process.Past and current perspectives Medical education has emerged as a complex transformative process of socialisation into the culture and profession of medicine. Theory and research, in medical education and other fields, have contributed important understanding. Learning theories arising from behaviourist, cognitivist, humanist and social learning traditions have guided improvements in curriculum design and instruction, understanding of memory, expertise and clinical decision making, and self-directed learning approaches. Although these remain useful, additional perspectives which recognise the complexity of education that effectively fosters the development of knowledge, skills and professional identity are needed.Future perspectives Socio-cultural learning theories, particularly situated learning, and communities of practice offer a useful theoretical perspective. They view learning as intimately tied to context and occurring through participation and active engagement in the activities of the community. Legitimate peripheral participation describes learners' entry into the community. As learners gain skill, they assume more responsibility and move more centrally. The community, and the people and artefacts within it, are all resources for learning. Learning is both collective and individual. Social cognitive theory offers a complementary perspective on individual learning. Situated learning allows the incorporation of other learning perspectives and includes workplace learning and experiential learning. Viewing medical education through the lens of situated learning suggests teaching and learning approaches that maximise participation and build on community processes to enhance both collective and individual learning. © Blackwell Publishing Ltd 2010.
Chen H.,China University of Mining and Technology |
Gu J.J.,Dalhousie University |
Gu J.J.,Shandong University
IEEE/ASME Transactions on Mechatronics | Year: 2013
This paper describes the developed three-phase 6/8 poles switched reluctance external rotor motor drive for a fan in air conditioner. The external rotor core structure and the internal stator core structure, the three-phase windings arrangement, the slotted claw, and the setting structure of the photoelectric transducers on the rotor position detector are illustrated. The electromagnetic field calculation results are given. The three-phase asymmetric bridge power converter was used in the drive system. The block diagram of the switched reluctance external rotor motor drive with closed-loop rotor speed control is given. The closed-loop rotor speed control is implemented using a fuzzy logic algorithm. The experimental tests of the developed prototype are made for driving the fan from 200 to 950 r/min. The comparison results of the two systems show that the input power and input phase current RMS value are lower in the developed three-phase 6/8 poles external rotor switched reluctance motor drive prototype with the fan than those in the induction motor variable-frequency variable-speed drive with the fan. © 1996-2012 IEEE.
Johnson L.S.M.,Dalhousie University
Journal of Medical Ethics | Year: 2011
The right to die has for decades been recognised for persons in a vegetative state, but there remains controversy about ending life-sustaining medical treatment for persons in the minimally conscious state (MCS). The controversy is rooted in assumptions about the moral significance of consciousness, and the value of life for patients who are conscious and not terminally ill. This paper evaluates these assumptions in light of evidence that generates concerns about quality of life in the MCS. It is argued that surrogates should be permitted to make decisions to withdraw life-sustaining medical treatment from patients in the MCS.
Ungar M.,Dalhousie University
American Journal of Orthopsychiatry | Year: 2011
More than two decades after E. E. Werner and R. S. Smith (1982), N. Garmezy (1983), and M. Rutter (1987) published their research on protective mechanisms and processes that are most likely to foster resilience, ambiguity continues regarding how to define and operationalize positive development under adversity. This article argues that, because resilience occurs even when risk factors are plentiful, greater emphasis needs to be placed on the role social and physical ecologies play in positive developmental outcomes when individuals encounter significant amounts of stress. Four principles are presented as the basis for an ecological interpretation of the resilience construct: decentrality, complexity, atypicality, and cultural relativity. These 4 principles, and the research upon which they are based, inform a definition of resilience that emphasizes the environmental antecedents of positive growth. This framework can guide future theory development, research, and the design of interventions that promote well-being among populations who experience environments that inhibit resilience-promoting processes. © 2011 American Orthopsychiatric Association.
Walker T.R.,Dalhousie University
Marine Pollution Bulletin | Year: 2016
European maritime companies have adopted programs to limit operational impacts on the environment. For maritime companies in North America, the Green Marine Environmental Program (GMEP) offers a framework to establish and reduce environmental footprints. Green Marine (GM) participants demonstrate annual improvements of specific environmental performance indicators (e.g., reductions in air pollution emissions) to maintain certification. Participants complete annual self-evaluations with results determining rankings for performance indicators on a 1-to-5 scale. Self-evaluations are independently verified every two years to ensure rigor and individual results are made publicly available annually to achieve transparency. GM benefits the marine industry across North America by encouraging sustainable development initiatives. GM's credibility is reflected through a diverse network of environmental groups and government agencies that endorse and help shape the program. Merits of this relatively new maritime certification (not previously described in the academic literature), are discussed. © 2016 Elsevier Ltd.
Fletcher J.A.,Dalhousie University
Clinical Journal of Sport Medicine | Year: 2013
The purpose of this paper is to look at the effects of exercise in the treatment and prevention of osteoporosis in athletes of all age groups. Recommendations for exercise programs will be discussed as a tool to improve bone health. Medical management of osteoporosis will be reviewed mainly as it pertains to postmenopausal women. © 2013 by Lippincott Williams & Wilkins.
Cantor M.,Dalhousie University
Philosophical transactions of the Royal Society of London. Series B, Biological sciences | Year: 2013
Culture is increasingly being understood as a driver of mammalian phenotypes. Defined as group-specific behaviour transmitted by social learning, culture is shaped by social structure. However, culture can itself affect social structure if individuals preferentially interact with others whose behaviour is similar, or cultural symbols are used to mark groups. Using network formalism, this interplay can be depicted by the coevolution of nodes and edges together with the coevolution of network topology and transmission patterns. We review attempts to model the links between the spread, persistence and diversity of culture and the network topology of non-human societies. We illustrate these processes using cetaceans. The spread of socially learned begging behaviour within a population of bottlenose dolphins followed the topology of the social network, as did the evolution of the song of the humpback whale between breeding areas. In three bottlenose dolphin populations, individuals preferentially associated with animals using the same socially learned foraging behaviour. Homogeneous behaviour within the tight, nearly permanent social structures of the large matrilineal whales seems to result from transmission bias, with cultural symbols marking social structures. We recommend the integration of studies of culture and society in species for which social learning is an important determinant of behaviour.
Clackdoyle R.,Dalhousie University |
Defrise M.,University of Geneva
IEEE Signal Processing Magazine | Year: 2010
Image reconstruction from projections is the field that lays the foundations for computed tomography (CT). For several decades, the established principles were applied not only to medical scanners in radiology and nuclear medicine but also to industrial scanning. When speaking of image reconstruction from projections, one is generally considering the problem of recovering some density function from measurements taken over straight lines, or the line-integral model for short. Image reconstruction can be performed by directly applying analytic formulas derived from the theory or by using general optimization methods adapted to handling large linear systems. The latter techniques are referred to as iterative to distinguish them from the analytic (or direct) methods. This article considers only the analytic methods. The two-dimensional (2-D) reconstruction problem (or classical tomography) refers to a density function in two dimensions with measurement lines lying in the plane, and the three-dimensional (3-D) problem considers 3-D density functions and lines with arbitrary orientations in space. The widely used term 3-D imaging is potentially confusing in this context, because there are some 3-D forms of image reconstruction that are mathematically equivalent to performing 2-D reconstruction on a set of parallel contiguous planes. To emphasize the distinction between 2-D and 3-D reconstruction, the terminology fully 3-D image reconstruction (or sometimes truly 3-D reconstruction) was introduced in the late 1980s when there seemed to be very little left to do in two dimensions but a rich unexplored 3-D theory to be developed. © 2006 IEEE.
Deacon S.H.,Dalhousie University
Behavioral and Brain Sciences | Year: 2012
Reading development is integral to a universal model of reading. Developmental research can tell us which factors drive reading acquisition and which are the product of reading. Like adult research, developmental research needs to be contextualised within the language and writing system and it needs to include key cross-linguistic evaluations. This will create a universal model of reading development. © 2012 Cambridge University Press.
Dupre D.J.,Dalhousie University
Sub-cellular biochemistry | Year: 2012
G protein coupled receptors are involved in highly efficient and specific activation of signaling pathways. Yet, we do not fully understand the processes required to assemble the different partners of the GPCR signaling complex. In order to address this issue, we need to understand how receptors and their signaling -partners are synthesized, folded and regulated during quality control steps in order to generate functional proteins. Several molecular chaperones are involved in this process for most proteins, including GPCRs. Several membrane proteins require the assembly of different subunits to be functional. In recent years, GPCRs have been shown to form oligomers, which could be interpreted as subunits of a larger complex. Yet, those oligomers would not be functional without the association of other signaling partners; thus, there is a requirement for the specific assembly of the -different partners. In this chapter, we will cover some aspects of the current knowledge about how chaperones are involved in both the formation of GPCR oligomers and in the assembly of the receptors with their signaling complex components.
Hall B.K.,Dalhousie University
Evolution and Development | Year: 2012
Parallelism has been the subject of a number of recent studies that have resulted in reassessment of the term and the process. Parallelism has been aligned with homology leaving convergence as the only case of homoplasy, regarded as a transition between homologous and convergent characters, and defined as the independent evolution of genetic traits. Another study advocates abolishing the term parallelism and treating all cases of the independent evolution of characters as convergence. With the sophistication of modern genomics and genetic analysis, parallelism of characters of the phenotype is being discovered to reflect parallel genetic evolution. Approaching parallelism from developmental and genetic perspectives enables us to tease out the degree to which the reuse of pathways represent deep homology and is a major task for evolutionary developmental biology in the coming decades. © 2012 Wiley Periodicals, Inc.
Uher R.,Kings College London |
Uher R.,Dalhousie University |
Rutter M.,Kings College London
World Psychiatry | Year: 2012
Current classification of eating disorders is failing to classify most clinical presentations; ignores continuities between child, adolescent and adult manifestations; and requires frequent changes of diagnosis to accommodate the natural course of these disorders. The classification is divorced from clinical practice, and investigators of clinical trials have felt compelled to introduce unsystematic modifications. Classification of feeding and eating disorders in ICD-11 requires substantial changes to remediate the shortcomings. We review evidence on the developmental and cross-cultural differences and continuities, course and distinctive features of feeding and eating disorders. We make the following recommendations: a) feeding and eating disorders should be merged into a single grouping with categories applicable across age groups; b) the category of anorexia nervosa should be broadened through dropping the requirement for amenorrhoea, extending the weight criterion to any significant underweight, and extending the cognitive criterion to include developmentally and culturally relevant presentations; c) a severity qualifier "with dangerously low body weight" should distinguish the severe cases of anorexia nervosa that carry the riskiest prognosis; d) bulimia nervosa should be extended to include subjective binge eating; e) binge eating disorder should be included as a specific category defined by subjective or objective binge eating in the absence of regular compensatory behaviour; f) combined eating disorder should classify subjects who sequentially or concurrently fulfil criteria for both anorexia and bulimia nervosa; g) avoidant/restrictive food intake disorder should classify restricted food intake in children or adults that is not accompanied by body weight and shape related psychopathology; h) a uniform minimum duration criterion of four weeks should apply.
Valach M.,University of Montreal |
Burger G.,University of Montreal |
Gray M.W.,Dalhousie University |
Lang B.F.,University of Montreal
Nucleic Acids Research | Year: 2014
5S Ribosomal RNA (5S rRNA) is a universal component of ribosomes, and the corresponding gene is easily identified in archaeal, bacterial and nuclear genome sequences. However, organelle gene homologs (rrn5) appear to be absent from most mitochondrial and several chloroplast genomes. Here, we re-examine the distribution of organelle rrn5 b y building mitochondrion- and plastid-specific covariance models (CMs) with which we screened organelle genome sequences. We not only recover all organelle rrn5genes annotated in GenBank records, but also identify more than 50 previously unrecognized homologs in mitochondrial genomes of various stramenopiles, red algae, cryptomonads, malawimonads and apusozoans, and surprisingly, in the apicoplast (highly derived plastid) genomes of the coccidian pathogens Toxoplasma gondii and Eimeria tenella. Comparative modeling of RNA secondary structure reveals that mitochondrial 5S rRNAs from brown algae adopt a permuted triskelion shape that has not been seen elsewhere. Expression of the newly predicted rrn5genes is confirmed experimentally in 10 instances, based on our own and published RNA-Seq data. This study establishes that particularly mitochondrial 5S rRNA has a much broader taxonomic distribution and a much larger structural variability than previously thought. The newly developed CMs will be made available via the Rfam database and the MFannot organelle genome annotator. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.
Sawynok J.,Dalhousie University
Handbook of Experimental Pharmacology | Year: 2011
Caffeine, an antagonist of adenosine A 1, A 2A and A 2B receptors, is known as an adjuvant analgesic in combination with non-steroidal anti-inflammatory drugs (NSAIDs) and acetaminophen in humans. In preclinical studies, caffeine produces intrinsic antinociceptive effects in several rodent models, and augments the actions of NSAIDs and acetaminophen. Antagonism of adenosine A 2A and A 2B receptors, as well as inhibition of cyclooxygenase activity at some sites, may explain intrinsic antinociceptive and adjuvant actions. When combined with morphine, caffeine can augment, inhibit or have no effect depending on the dose, route of administration, nociceptive test and species; inhibition reflects spinal inhibition of adenosine A 1 receptors, while augmentation may reflect the intrinsic effects noted above. Low doses of caffeine given systemically inhibit antinociception by several analgesics (acetaminophen, amitriptyline, oxcarbazepine, cizolirtine), probably reflecting block of a component of action involving adenosine A 1 receptors. Clinical studies have demonstrated adjuvant analgesia, as well as some intrinsic analgesia, in the treatment of headache conditions, but not in the treatment of postoperative pain. Caffeine clearly exhibits complex effects on pain transmission; knowledge of such effects is important for understanding adjuvant analgesia as well as considering situations in which dietary caffeine intake may have an impact on analgesic regimens. © 2011 Springer Berlin Heidelberg.
Doolittle W.F.,Dalhousie University
Current Biology | Year: 2012
Two processes suggested to drive bacterial speciation - periodic selection and recombination - are generally thought to be mutually opposed. Recent work shows that data taken as evidence supporting the former may be explained by the latter, raising further problems for the idea of bacterial 'species'. © 2012 Elsevier Ltd.
Hong P.,Dalhousie University
American Journal of Otolaryngology - Head and Neck Medicine and Surgery | Year: 2014
Background Thyroglossal duct cysts are usually managed with the Sistrunk procedure, which involves excision of the cervical cyst with the central portion of the hyoid bone, along with its tract. Surgical drains are commonly placed with this procedure, which necessitates postoperative hospital admission.Objective The aim of this study is to determine if surgical drain placement is necessary in pediatric patients who underwent the Sistrunk procedure.Methods The current study describes the outcomes of 30 consecutive children who underwent the Sistrunk procedure without drain placement. Complication rates are compared to an age-matched control group who had drains placed.Results No major complications, including hematomas were observed in the study group; outpatient surgery was safely observed in 20 patients. No significant difference in complication rates was observed between the study and control groups.Conclusions Routine drain placement in children who are undergoing the Sistrunk procedure may not be necessary. Subsequently, postoperative admission may be avoided. © 2014 Elsevier Inc.
Moreside J.M.,Dalhousie University |
Mcgill S.M.,University of Waterloo
Journal of Strength and Conditioning Research | Year: 2013
The purpose of this study was to analyze the transference of increased passive hip range of motion (ROM) and core endurance to functional movement. Twenty-four healthy young men with limited hip mobility were randomly assigned to 4 intervention groups: group 1, stretching; group 2, stretching plus hip/spine disassociation exercises; group 3, core endurance; and group 4, control. Previous work has documented the large increase in passive ROM and core endurance that was attained over the 6-week interventions, but whether these changes transferred to functional activities was unclear. Four dynamic activities were analyzed before and after the 6-week interventions: active standing hip extension, lunge, a standing twist/reach maneuver, and exercising on an elliptical trainer. A Vicon motion capture system collected body segment kinematics, with hip and lumbar spine angles subsequently calculated in Visual 3D. Repeated measures analyses of variance determined group effects on various hip and spine angles, with paired t-tests on specific pre/post pairs. Despite the large increases in passive hip ROM, there was no evidence of increased hip ROM used during functional movement testing. Similarly, the only significant change in lumbar motion was a reduction in lumbar rotation during the active hip extension maneuver (p , 0.05). These results indicate that changes in passive ROM or core endurance do not automatically transfer to changes in functional movement patterns. This implies that training and rehabilitation programs may benefit from an additional focus on "grooving" new motor patterns if newfound movement range is to be used.©2013 National Strength and Conditioning Association.
Guedes R.N.C.,Federal University of Vicosa |
Cutler G.C.,Dalhousie University
Pest Management Science | Year: 2014
Ecological backlashes such as insecticide resistance, resurgence and secondary pest outbreaks are frequent problems associated with insecticide use against arthropod pest species. The last two have been particularly important in sparking interest in the phenomenon of insecticide-induced hormesis within entomology and acarology. Hormesis describes a biphasic dose-response relationship that is characterized by a reversal of response between low and high doses of a stressor (e.g. insecticides). Although the concept of insecticide-induced hormesis often does not receive sufficient attention, or has been subject to semantic confusion, it has been reported in many arthropod pest species and natural enemies, and has been linked to pest outbreaks and potential problems with insecticide resistance. The study of hormesis remains largely neglected in entomology and acarology. Here, we examined the concept of insecticide-induced hormesis in arthropods, its functional basis and potential fitness consequences, and its importance in arthropod pest management and other areas. © 2013 Society of Chemical Industry.
Martovetsky G.,University of California at San Diego |
Tee J.B.,Dalhousie University |
Nigam S.K.,University of California at San Diego
Molecular Pharmacology | Year: 2013
The transcriptional regulation of drug-metabolizing enzymes and transporters (here collectively referred to as DMEs) in the developing proximal tubule (PT) is not well understood. As in the liver, DME regulation in the PT may be mediated through nuclear receptors, which are thought to "sense" deviations from homeostasis by being activated by ligands, some of which are handled by DMEs, including drug transporters. Systems analysis of transcriptomic data during kidney development predicted a set of upstream transcription factors, including hepatocyte nuclear factor 4α (Hnf4a) and Hnf1a, as well as Nr3c1 (Gr), Nfe2l2 (Nrf2), peroxisome proliferator-activated receptor α (Pparα), and Tp53. Motif analysis of cis-regulatory enhancers further suggested that Hnf4a and Hnf1a are the main transcriptional regulators of DMEs in the PT. Available expression data from tissue-specific Hnf4a knockout tissues revealed that distinct subsets of DMEs were regulated by Hnf4a in a tissue-specific manner. Chromatin immunoprecipitation combined with massively parallel DNA sequencing was performed to characterize the PT-specific binding sites of Hnf4a in rat kidneys at three developmental stages (prenatal, immature, adult), which further supported a major role for Hnf4a in regulating PT gene expression, including DMEs. In ex vivo kidney organ culture, an antagonist of Hnf4a (but not a similar inactive compound) led to predicted changes in DME expression, including among others Fmo1, Cyp2d2, Cyp2d4, Nqo2, as well as organic cation transporters and organic anion transporters Slc22a1 (Oct1), Slc22a2 (Oct2), Slc22a6 (Oat1), Slc22a8 (Oat3), and Slc47a1 (Mate1). Conversely, overexpression of Hnf1a and Hnf4a in primary mouse embryonic fibroblasts, sometimes considered a surrogate for mesenchymal stem cells, induced expression of several of these proximal tubule DMEs, as well as epithelial markers and a PT-enriched brush border marker Ggt1. These cells had organic anion transporter function. Taken together, the data strongly supports a critical role for HNF4a and Hnf1a in the tissue-specific regulation of drug handling and differentiation toward a PT-like cellular identity. We discuss our data in the context of the "remote sensing and signaling hypothesis" (Ahn and Nigam, 2009; Wu et al., 2011). Copyright © 2013 by The American Society for Pharmacology and Experimental Therapeutics.
Simpson C.,Dalhousie University
Healthcare Papers | Year: 2015
Fooks et al. (2015) propose patient-centred care and engagement as "levers for change" in a healthcare system increasingly challenged to care for patients living with complex chronic illness. Patient-centred care, engagement and experience are presented as inherently relational concepts, but who is included under that relational umbrella is less clear. Using the rubric of "finding common ground" from the model of patient-centred care described by Hudon et al. (2011), I argue for including provider perspectives, not just patient/family. Otherwise the envisioned conversations of "change" will be missing the voices of those expected to facilitate the meaningful relational engagement of patients and the process of shared decision-making. I also discuss relational communication competence as a key factor in successful patientengagement, patient-centred care and, ultimately, the healthcare experience. Without attention to both these elements - broadening the understanding of therapeutic relationship to encompass all contributing stakeholders and the relational communication competency so necessary to this endeavour - whatever consensus we reach will be missing important aspects related to actionable content and process, both of which are needed to guide the development of relevant metrics. Without metrics, we will lack rigorous "evidence" with which to make the case that patient-centred care and engagement are indeed "levers" for positive system reform.
Oliver E.C.J.,Dalhousie University
International Journal of Climatology | Year: 2015
Atmospheric and oceanic reanalyses are used widely by the climate science community. These products provide full three-dimensional state fields and gapless time series, along with the confidence of being constrained by observational measurements, for atmospheric scientists and oceanographers to use in analyses of the climate system. However, as ubiquitous as reanalysis data are, it is not often considered how a scarcity of measurements in certain poorly observed regions, or over the course of a long period of time in which the observational system has changed significantly, impacts the realism of the data. This study explores this question using tropical surface pressures from the Twentieth Century Reanalysis to hindcast an index of the Madden-Julian Oscillation (MJO) over the 20th century. We show that by changing the choice of surface pressure predictor locations, and being aware of the observational measurements that have been assimilated by the reanalysis system, it is possible to control the estimated centennial-scale trend in MJO activity from nearly zero to an increase of 30% over the 20th century. We emphasize that this is an apparent trend as it arises solely from the use of reanalyzed surface pressures from locations that have either been poorly observed or have experienced significant changes in the observing system over the 20th century. This highlights the need to be aware of the observational measurements (or lack of them), particularly their density in space and time, that have been assimilated by a reanalysis system. © 2015 Royal Meteorological Society.
Uher R.,Dalhousie University
Genome Medicine | Year: 2013
Coinciding with the release of the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders, two recently published molecular genetics analyses suggest large overlaps in genetic liability to schizophrenia, bipolar disorder and major depressive disorder. This indicates that a broader category of severe mental illness may be an important target for future large-scale etiological and therapeutic investigations. Studies of patient groups not restricted to current diagnostic categories may lead to a genetically informed nosology. © 2013 BioMed Central Ltd.
Becke A.D.,Dalhousie University
Journal of Chemical Physics | Year: 2013
In this work, our exact-exchange-based static + dynamical correlation density functional [A. D. Becke, J. Chem. Phys. 122, 064101 (2005)]10.1063/1. 1844493 is generalized to include "strong" correlation, i.e., accurate computations on dissociating chemical systems without breaking space or spin symmetries and without using multi-determinantal reference states. Also, we introduce a strong-correlation benchmark set composed of space- and spin-symmetrized open-shell atoms on which the generalized functional is tested. Initial results are very promising. © 2013 American Institute of Physics.
Metaxas A.,Dalhousie University
Marine Ecology Progress Series | Year: 2011
Because of their ephemeral nature and patchy distribution, hydrothermal vents on mid-ocean ridges are newly colonized by allochthonous larval sources after catastrophic eruptions, but their hydrothermal benthic invertebrate populations are maintained by local larval supply. In the present study, I examined spatial patterns of larval abundance and associated adult assemblages at hydrothermal vents on 3 seamounts each at the Mariana Arc and Kermadec-Tonga Arc. Because seamounts are topographically distinct features on the ocean floor, colonization processes may differ from those on mid-ocean ridges. On every seamount, the chemosynthetically based macro-epifaunal populations were patchy, spatially constrained and consisting of 1 to 3 numerically dominant taxa that differed among locations within a seamount and among seamounts. Larval abundance was generally greater at 2-7 m above the sea floor than 20-30 m higher, and in 5 of the 6 seamounts, it was lower than has been measured at the same elevations in previous studies on mid-ocean ridges. I examined changes in vertical distribution in experiments using 2 vent species of gastropod larvae hatched from egg capsules collected in situ. For Shinkailepas cf. kaikatensis, larvae were initially more abundant near the water surface, but were more abundant near the bottom 3 d after hatching, whereas for Shinkailepas n. sp., they remained near the bottom for the duration of the experiment. The observed larval distributions in the field and experiments suggest high larval retention, which can result in high local recruitment, but low colonization of new locations within or among seamounts. In combination with gregarious settlement and potentially limited habitat availability, low colonization is likely to give rise to the paucity of the adult chemosynthetic assemblages observed in the present study, and effect recruitment limitation beyond the local source population of vent species on highly disturbed seamounts that are volcanically active. © Inter-Research 2011.
Dingle R.N.,Dalhousie University
The Journal of the Acoustical Society of America | Year: 2012
The current understanding of mammalian sound localization is that azimuthal (horizontal) position assignments are dependent upon the relative activation of two populations of broadly-tuned hemifield neurons with overlapping medial borders. Recent psychophysical work has provided evidence for a third channel of low-frequency interaural time difference (ITD)-sensitive neurons tuned to the azimuthal midline. However, the neurophysiological data on free-field azimuth receptive fields, especially of cortical neurons, has primarily studied high-frequency cells whose receptive fields are more likely to have been shaped by interaural level differences (ILDs) than ITDs. In four experiments, a selective adaptation paradigm was used to probe for the existence of a midline channel in the domain of ILDs. If no midline channel exists, symmetrical adaptation of the lateral channels should not result in a shift in the perceived intracranial location of subsequent test tones away from the adaptors because the relative activation of the two channels will remain unchanged. Instead, results indicate a shift in perceived test tone location away from the adaptors, which supports the existence of a midline channel in the domain of ILDs. Interestingly, this shift occurs not only at high frequencies, traditionally associated with ILDs in natural settings, but at low frequencies as well.
Luchtman D.W.,University of Alberta |
Song C.,Chinese Academy Engineer Institute for the Development of Endangered Medicinal Resource in Southwest of China |
Song C.,Dalhousie University
Neuropharmacology | Year: 2013
Omega-(n)-3 polyunsaturated fatty acids (PUFAs), including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are major components of neuronal membranes and have a wide range of functions, from modulating synaptic plasticity and neurochemistry, to neuroimmune-modulation and neuroprotection. Thus, it is not surprising that n-3 PUFA are widely acknowledged to have cognitive-enhancing effects. Although clinical evidence is somewhat conflicting, probably in large part due to methodological issues, animal studies have consistently demonstrated that n-3 PUFA are indispensable for proper brain development, may enhance cognitive function in healthy, adult individuals and attenuate cognitive impairment in aging and age-related disorders, such as dementia. This review discusses and integrates up to date evidence from clinical and animal studies investigating the cognitive-enhancing effects of n-3 PUFA during development, child- and adult-hood, as well as old-age with associated neurodegenerative diseases, such as Alzheimer's disease. Furthermore, we cover the major underlying biochemical and neurophysiological mechanisms by which n-3 PUFA mediate these effects on cognition. This article is part of a Special Issue entitled 'Cognitive Enhancers'. © 2012 Elsevier Ltd. All rights reserved.
Zaphiratos V.,Dalhousie University
Anesthesia and Analgesia | Year: 2016
BACKGROUND:: Combined spinal-epidural (CSE) analgesia is widely used for delivering labor analgesia. Epidural volume extension (EVE) involves the injection of fluid into the epidural space compressing the dural sac, causing cephalad shift of the cerebral spinal fluid. Our hypothesis was that EVE with 10 mL normal saline during CSE would increase the sensory block height at 15 minutes after intrathecal injection. We expected EVE to decrease pain scores, decrease analgesia onset time, and decrease motor block compared with performing CSE without EVE (NEVE). METHODS:: We randomly assigned 60 healthy term laboring nulliparous parturients with cervical dilation <5 cm to receive CSE either with EVE of 10 mL normal saline through the Tuohy needle before catheter insertion or CSE NEVE. Intrathecal analgesia consisted of 2 mg plain bupivacaine and 10 μg fentanyl (1 mL total). A blinded researcher assessed sensory dermatome level, analgesia, and motor blockade at regular intervals for 30 minutes. The primary outcome measure was the median peak sensory dermatome level at 15 minutes. RESULTS:: Fifty-four parturients were analyzed. There was no significant difference in peak sensory dermatome levels at 15 minutes (median difference, 1 dermatome level; 95% confidence interval of median difference, 0 to 2; P = 0.22) and 30 minutes (median difference, 0 dermatome level; 95% confidence interval, −2 to 2; P = 0.76). There was no difference in the time to peak dermatome, minimum pain score, or the time to minimum pain score between groups. CONCLUSIONS:: We found no significant difference between groups with regard to sensory dermatome level or pain scores when using EVE compared with NEVE. Our study demonstrates that addition of EVE does not offer superior analgesia when using a CSE technique for parturients requesting labor analgesia. © 2016 International Anesthesia Research Society
Tavori H.,Oregon Health And Science University |
Rashid S.,Dalhousie University |
Fazio S.,Oregon Health And Science University
Atherosclerosis | Year: 2015
Proprotein convertase subtilisin kexin type 9 (PCSK9) is a circulatory ligand that terminates the lifecycle of the low-density lipoprotein (LDL) receptor (LDLR) thus affecting plasma LDL-cholesterol (LDL-C) levels. Recent evidence shows that in addition to the straightforward mechanism of action, there are more complex interactions between PCSK9, LDLR and plasma lipoprotein levels, including: (a) the presence of both parallel and reciprocal regulation of surface LDLR and plasma PCSK9; (b) a correlation between PCSK9 and LDL-C levels dependent not only on the fact that PCSK9 removes hepatic LDLR, but also due to the fact that up to 40% of plasma PCSK9 is physically associated with LDL; and (c) an association between plasma PCSK9 production and the assembly and secretion of triglyceride-rich lipoproteins. The effect of PCSK9 on LDLR is being successfully utilized toward the development of anti-PCSK9 therapies to reduce plasma LDL-C levels. Current biochemical research has uncovered additional mechanisms of action and interacting partners for PCSK9, and this opens the way for a more thorough understanding of the regulation, metabolism, and effects of this interesting protein. © 2014 Elsevier Ireland Ltd.
Tong X.,University of Hong Kong |
Deacon S.H.,Dalhousie University |
Cain K.,Lancaster University
Journal of Learning Disabilities | Year: 2014
Poor comprehenders have intact word-reading skills but struggle specifically with understanding what they read. We investigated whether two metalinguistic skills, morphological and syntactic awareness, are specifically related to poor reading comprehension by including separate and combined measures of each. We identified poor comprehenders (n = 15) and average comprehenders (n = 15) in Grade 4 who were matched on word-reading accuracy and speed, vocabulary, nonverbal cognitive ability, and age. The two groups performed comparably on a morphological awareness task that involved both morphological and syntactic cues. However, poor comprehenders performed less well than average comprehenders on a derivational word analogy task in which there was no additional syntactic information, thus tapping only morphological awareness, and also less well on a syntactic awareness task, in which there were no morphological manipulations. Our task and participant-selection process ruled out key nonmetalinguistic sources of influence on these tasks. These findings suggest that the relationships among reading comprehension, morphological awareness, and syntactic awareness depend on the tasks used to measure the latter two. Future research needs to identify precisely in which ways these metalinguistic difficulties connect to challenges with reading comprehension. © Hammill Institute on Disabilities 2013.
Kaake L.G.,University of California at Santa Barbara |
Jasieniak J.J.,University of California at Santa Barbara |
Bakus R.C.,University of California at Santa Barbara |
Welch G.C.,Dalhousie University |
And 3 more authors.
Journal of the American Chemical Society | Year: 2012
Understanding the charge generation dynamics in organic photovoltaic bulk heterojunction (BHJ) blends is important for providing the necessary guidelines to improve overall device efficiency. Despite more than 15 years of experimental and theoretical studies, a universal picture describing the generation and recombination processes operating in organic photovoltaic devices is still being forged. We report here the results of ultrafast transient absorption spectroscopy measurements of charge photogeneration and recombination processes in a high-performing solution-processed molecular BHJ. For comparison, we also studied a high-performing polymer-based BHJ material. We find that the majority of charge carriers in both systems are generated on <100 fs time scales and posit that excited state delocalization is responsible for the ultrafast charge transfer. This initial delocalization is consistent with the fundamental uncertainty associated with the photon absorption process (in the visible, l/4π > 30 nm) and is comparable with the phase-separated domain size. In addition, exciton diffusion to charge-separating heterojunctions is observed at longer times (1-500 ps). Finally, charge generation in pure films of the solution processed molecule was studied. Polarization anisotropy measurements clearly demonstrate that the optical properties are dominated by molecular (Frenkel) exictons and delocalized charges are promptly produced (t < 100 fs). © 2012 American Chemical Society.
Valiquette F.,Dalhousie University
Differential Geometry and its Application | Year: 2012
The method of equivariant moving frames is used to obtain the equations governing the evolution of the differential invariants of an invariant affine symplectic curve flow in R 4 preserving arc length. Conditions guaranteeing that a geometric curve flow produces Hamiltonian evolution equations are obtained. Finally, we show that a constant tangential curve flow produces bi-Hamiltonian evolution equations. © 2012 Elsevier B.V.
Udenigwe C.C.,Dalhousie University
Food Chemistry | Year: 2016
Abstract Rice bran proteins (RBP) have been demonstrated to harbour biologically active peptides, which can be released by proteases and applied in human health promotion. In this study, the roles of rice bran cysteine protease inhibitors, oryzacystatins, were considered for efficient production of bioactive peptides from RBP. In silico evidence demonstrates that aspartate protease (pepsin at pH > 2) and metalloproteinase (thermolysin) have strong prospects for use in simultaneously cleaving the QXVXGX motif of oryzacystatins, which can lead to their inactivation, and in releasing bioactive sequences from the protease inhibitors. The cleaved bioactive peptides are known to possess activities that can be applied in the management of hypertension, oxidative stress, type 2 diabetes mellitus and other aberrant cellular processes. Moreover, several potentially bioactive di- and tripeptides were identified in oryzacystatin peptide pools. This study provides an important consideration and a direction that can lead to efficient release of bioactive peptides from rice bran proteins for functional food applications. © 2015 Elsevier Ltd.
France R.L.,Dalhousie University
Hydrobiologia | Year: 2014
Widespread omnivory in aquatic food webs has been recognized to compromise interpretation of Lindeman's "pyramid of energy" wherein organism biomass is constrained into rigidly delineated trophic levels. A compilation of global, pre-1997 stable nitrogen isotope data for aquatic food webs produced vertical energy profiles that were ataxonomic and therefore similar to Elton's "pyramid of numbers" which he believed to be based on size-structured feeding relationships. Further, the present secondary-analysis confirms findings from other recent data compilations in suggesting that aquatic animals in real food webs are rarely found above the fifth or sixth broadly based trophic category. Therefore, δ15N analysis of food webs permits a reconciliation between theoreticians and empiricists by assuming a middle position in estimates made of the vertical length of food webs. © 2013 Springer Science+Business Media Dordrecht.
Carson V.,University of Alberta |
Stone M.,Dalhousie University |
Faulkner G.,University of Toronto
Pediatric Exercise Science | Year: 2014
To make robust conclusions regarding the association between accelerometer-measured sedentary time and overweight and obesity among children, several gaps in the literature must be addressed. The purpose of this study was to examine associations between sedentary time, weekday sedentary time, weekend sedentary time, sedentary bouts, sedentary breaks, and BMI z-score among children and by low (bottom 50%) and high (top 50%) moderate- to vigorous-intensity physical activity (MVPA) participation. Results are based on 787 children aged 11 years living in Toronto, Canada. Children's physical activity and sedentary time were objectively assessed using ActiGraph accelerometers in 2010/11. Height and weight were measured and BMI z-scores were calculated based on the World Health Organization growth standards. When participants were stratified into low and high MVPA groups, sedentary bouts of 5-9 (β = 0.22 [95% CI: 0.01, 0.43]) and 10-19 (0.30 [0.05, 0.55]) minutes for total days were associated with BMI z-score in the low MVPA group only. Similar trends were observed with the weekday but not the weekend variables. Therefore, in addition to increasing MVPA, reducing time spent in 5- to 19-min sedentary bouts may have important implications for weight status particularly for children with lower MVPA participation during the week. © 2014 Human Kinetics, Inc.
De Santo E.M.,Dalhousie University
Marine Policy | Year: 2011
This paper examines the implications of environmental justice in the regime for Maritime Spatial Planning (MSP) currently developing in the European Union (EU). An 'ecosystem-based approach' to marine management is enshrined in the new Integrated Maritime Policy and Marine Strategy Framework Directive and forms the basis of MSP. This concept is intended to encompass all aspects of an ecosystem, including the human element. Yet the modes of including meaningful public participation in the decision-making process for MSP remain undetermined. At the same time, the Aarhus Convention (on access to information, public participation in decision making and access to justice in environmental matters) empowers non-governmental organisations to hold EU Member States to account. Consequently the issue of transparency will gain increased importance, as will linkages between human and environmental rights. Such public interest-based activism on the part of NGOs has the potential to enforce the developing framework for stakeholder engagement within MSP, but it also has implications worth considering regarding the appropriate role of interest-based organisations in the international political arena. © 2010 Elsevier Ltd.
Becke A.D.,Dalhousie University
Journal of Chemical Physics | Year: 2014
Since its formal inception in 1964-1965, Kohn-Sham density-functional theory (KS-DFT) has become the most popular electronic structure method in computational physics and chemistry. Its popularity stems from its beautifully simple conceptual framework and computational elegance. The rise of KS-DFT in chemical physics began in earnest in the mid 1980s, when crucial developments in its exchange-correlation term gave the theory predictive power competitive with well-developed wave-function methods. Today KS-DFT finds itself under increasing pressure to deliver higher and higher accuracy and to adapt to ever more challenging problems. If we are not mindful, however, these pressures may submerge the theory in the wave-function sea. KS-DFT might be lost. I am hopeful the Kohn-Sham philosophical, theoretical, and computational framework can be preserved. This Perspective outlines the history, basic concepts, and present status of KS-DFT in chemical physics, and offers suggestions for its future development. © 2014 AIP Publishing LLC.
Linsdell P.,Dalhousie University
Biochimica et Biophysica Acta - Biomembranes | Year: 2015
Binding of cytoplasmic anionic open channel blockers within the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel is antagonized by extracellular Cl-. In the present work, patch clamp recording was used to investigate the interaction between extracellular Cl- (and other anions) and cytoplasmic Pt(NO2)42 - ions inside the CFTR channel pore. In constitutively open (E1371Q-CFTR) channels, these different anions bind to two separate sites, located in the outer and inner vestibules of the pore respectively, in a mutually antagonistic fashion. A mutation in the inner vestibule (I344K) that greatly increased Pt(NO2)42 - binding affinity also greatly strengthened antagonistic Cl-:blocker interactions as well as the voltage-dependence of block. Quantitative analysis of ion binding affinity suggested that the I344K mutation strengthened interactions not only with intracellular Pt(NO2)42 - ions but also with extracellular Cl-, and that altered blocker Cl-- and voltage-dependence were due to the introduction of a novel type of antagonistic ion:ion interaction inside the pore that was independent of Cl- binding in the outer vestibule. It is proposed that this mutation alters the arrangement of anion binding sites inside the pore, allowing both Cl- and Pt(NO2)42 - to bind concurrently within the inner vestibule in a strongly mutually antagonistic fashion. However, the I344K mutation does not increase single channel conductance following disruption of Cl- binding in the outer vestibule in R334Q channels. Implications for the arrangement of ion binding sites in the pore, and their functional consequences for blocker binding and for rapid Cl- permeation, are discussed. © 2015 Elsevier B.V.
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.
Gillis J.A.,University of Cambridge |
Gillis J.A.,National Oceanic and Atmospheric Administration |
Gillis J.A.,Dalhousie University |
Modrell M.S.,University of Cambridge |
Baker C.V.H.,University of Cambridge
Nature Communications | Year: 2013
Gegenbaur's classical hypothesis of jaw-gill arch serial homology is widely cited, but remains unsupported by either palaeontological evidence (for example, a series of fossils reflecting the stepwise transformation of a gill arch into a jaw) or developmental genetic data (for example, shared molecular mechanisms underlying segment identity in the mandibular, hyoid and gill arch endoskeletons). Here we show that nested expression of Dlx genes - the 'Dlx code' that specifies upper and lower jaw identity in mammals and teleosts - is a primitive feature of the mandibular, hyoid and gill arches of jawed vertebrates. Using fate-mapping techniques, we demonstrate that the principal dorsal and ventral endoskeletal segments of the jaw, hyoid and gill arches of the skate Leucoraja erinacea derive from molecularly equivalent mesenchymal domains of combinatorial Dlx gene expression. Our data suggest that vertebrate jaw, hyoid and gill arch cartilages are serially homologous, and were primitively patterned dorsoventrally by a common Dlx blueprint. © 2013 Macmillan Publishers Limited.
Blanchard C.M.,Dalhousie University
Exercise and Sport Sciences Reviews | Year: 2012
Physical activity (PA) adherence is a problem that has plagued cardiovascular disease patients for years. Because of this, researchers have advocated for the identification of key theoretical correlates that can be used to guide PA intervention development. The present review will identify key PA correlates for these patients and provide subsequent recommendations to look beyond patient-level correlates. Copyright © 2011 by the American College of Sports Medicine.
Boudreau B.P.,Dalhousie University
Marine and Petroleum Geology | Year: 2012
This paper reviews current understanding of the physics of bubbles in soft (unlithified), cohesive sediments, certainly in the top 100 m from the sediment-water interface, but likely much deeper. Experimental evidence, primarily CT scans and internal pressure records, indicate that near-surface bubbles grow by elastically compressing and fracturing these sediments, which results in thin, irregular disks of gas. These data do not suggest either plastic or fluid behavior on the part of the bulk sediment. In addition there is no hint of capillary invasion of gas into the pores of fine-grained sediments. The growth rate of an elastic-fracturing, disk-shaped, bubble can vastly exceed that of a spherical bubble, depending on the eccentricity of the bubble. This effect results from the far more favorable surface-to-volume ratio of flattened bubbles. The initial rate of rise of bubbles in cohesive sediments also appears to be governed by a fracture process, which is driven by pseudo-buoyancy. The rate of bubble rise could be controlled by various possible mechanisms, but only the predictions from a visco-elastic-fracture propagation model seem to produce rise velocities that are not ballistic (
Jones A.,University of Southern Denmark |
Vallis M.,Dalhousie University |
Pouwer F.,University of Tilburg
Diabetic Medicine | Year: 2015
Despite improvements in pharmacological treatments and methods of care and care delivery, the burden of living with diabetes remains an ongoing challenge, as many people with diabetes are at increased risk of mental health disorders, psychological disturbances and functional problems associated with living with diabetes. Person-centred collaborative care that also meets the psychological needs of the individual is not available to many people with diabetes. The present article examines the role of psychological factors in the onset of diabetes and in relation to living with diabetes. It is argued that the pursuit of psychological well-being is worthy of individual attention in the care of people with diabetes and should not be contingent upon attainment of somatic indices of health. The barriers to attaining this goal are examined, including the costs of treating (or not treating) psychological problems in people with diabetes. Recommendations on how to improve diabetes care are offered, including psychological interventions that are both evidence-based and cost-effective. © 2014 Diabetes UK.
Howlett S.E.,Dalhousie University
American Journal of Physiology - Heart and Circulatory Physiology | Year: 2010
We evaluated effects of age on components of excitation-contraction (EC) coupling in ventricular myocytes from male and female rats to examine sex differences in mechanisms responsible for age-related contractile dysfunction. Myocytes were isolated from anesthetized young adult (∼3 mo) and aged (∼24 mo) Fischer 344 rats. Ca2+ concentrations and contractions were measured simultaneously (37° C, 2 Hz). Fractional shortening declined with age in males (6.7 ± 0.6% to 2.4 ± 0.4%; P < 0.05), as did peak Ca2+ transients (47.7 ± 4.6 to 28.1 ± 2.1 nM; P < 0.05) and Ca2+ current densities (-7.7 ± 0.7 to -6.2 ± 0.5 pA/pF; P < 0.05). Although sarcoplasmic reticulum (SR) Ca 2+ content was similar regardless of age in males, EC coupling gain declined significantly with age to 55.8 ± 7.8% of values in younger males. In contrast with results in males, contraction and Ca2+ transient amplitudes were unaffected by age in females. Ca2+ current density declined with age in females (-7.5 ± 0.5 to -5.1 ± 0.7 pA/pF; P < 0.05), but SR Ca2+ content actually increased dramatically (49.0 ± 7.5 to 147.3 ± 28.5 nM; P < 0.05). Even so, EC coupling gain was not affected by age in female myocytes. Age also promoted hypertrophy of male myocytes more than female myocytes. Age and sex differences in EC coupling were largely maintained when conditioning pulse frequency was increased to 4 Hz. Contractions, Ca2+ transients, and EC coupling gain were also smaller in young females than in young males. Thus age-dependent changes are more prominent in myocytes from males than females. Increased SR Ca2+ content may compensate for reduced Ca2+ current to preserve contractile function in aged females, which may limit the detrimental effects of age on cardiac contractile function. Copyright © 2010 the American Physiological Society.
Chitnis S.S.,University of Victoria |
Carpenter Y.-Y.,Dalhousie University |
Burford N.,University of Victoria |
McDonald R.,University of Alberta |
Ferguson M.J.,University of Alberta
Angewandte Chemie - International Edition | Year: 2013
Square deal: Reactions of SbF3 with Me3SiOSO 2CF3 produce Sb3+ and [Sb-F]2+ cations, which form complexes with two or three Me3P ligands. Subsequent reductive elimination of diphosphonium or fluorophosphonium cations from the complexes give the folded square cyclo-[(Me3P) 4Sb4][OTf]4. Formation of the tetracation framework reveals new redox chemistry for Sb. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Ng E.S.W.,Dalhousie University |
Law A.,Trent University
Canadian Journal on Aging | Year: 2014
How do older workers keep up and adapt to a changing workplace after age 55? In exploring that question, this study specifically examined how age-related changes affect workers, how older workers deal with a loss of resources, how they engage in life management, and why some are more successful than others. An in-depth analysis was undertaken using 32 semi-structured interviews conducted with workers aged 55 to 64. Findings revealed that older workers use various strategies to adapt to a change in resources, and that these strategies help them cope and maintain their functioning in the workplace. Because older workers require different types of employer support, this study offers an understanding of how employers can provide that support to encourage older workers to remain in the workforce longer. Several avenues for future research are suggested, including an exploration of the role played by internal sources of support. © 2013 Canadian Association on Gerontology.
Susko E.,Dalhousie University
Systematic Biology | Year: 2011
Generalized least squares (GLS) methods provide a relatively fast means of constructing a confidence set of topologies. Because they utilize information about the covariances between distances, it is reasonable to expect additional efficiency in estimation and confidence set construction relative to other least squares (LS) methods. Difficulties have been found to arise in a number of practical settings due to estimates of covariance matrices being ill conditioned or even noninvertible. We present here new ways of estimating the covariance matrices for distances that are much more likely to be positive definite, as the actual covariance matrices are. A thorough investigation of performance is also conducted. An alternative to GLS that has been proposed for constructing confidence sets of topologies is weighted least squares (WLS). As currently implemented, this approach is equivalent to the use of GLS but with covariances set to zero rather than being estimated. In effect, this approach assumes normality of the estimated distances and zero covariances. As the results here illustrate, this assumption leads to poor performance. A 95% confidence set is almost certain to contain the true topology but will contain many more topologies than are needed. On the other hand, the results here also indicate that, among LS methods, WLS performs quite well at estimating the correct topology. It turns out to be possible to improve the performance of WLS for confidence set construction through a relatively inexpensive normal parametric bootstrap that utilizes the same variances and covariances of GLS. The resulting procedure is shown to perform at least as well as GLS and thus provides a reasonable alternative in cases where covariance matrices are ill conditioned. © 2011 The Author(s).
Gabriel C.-E.,St. Francis Xavier University |
Gabriel C.-E.,Dalhousie University |
Kellman L.,St. Francis Xavier University
Soil Biology and Biochemistry | Year: 2014
Temperature and moisture are primary environmental drivers of soil organic matter (SOM) decomposition, and an improved understanding of how they interact to control SOM cycling processes in temperate forest soils is needed. Intact soil cores from shallow (0-25cm) and deep (25-50cm) mineral soils were incubated under constant and/or diurnal temperature regimes, and subjected to a series of moisture manipulations within a climate-controlled facility. Soil temperature, moisture, and CO2 efflux were monitored daily for all intact cores and monitored continuously on a subset of cores in order to establish predictive relationships between these variables. Moisture constraints upon the decomposition of SOM were observed below 0.20 and above 0.60 water filled pore space (WFPS) for all shallow mineral soils, and below 0.40 WFPS for shallow soils that had been recently rewet. These thresholds were also evidenced in phase lags between respiration and temperature at 5cm at high moisture contents, suggesting that while biological responses drive soil respiration at low moisture contents, diffusivity limits the response at high soil moisture. While the shallow mineral soil dominated the contribution to CO2 flux and consistently generated short term responses to rewetting events, deep mineral soil layers respired an order of magnitude lower than shallow layers (per gram C) with no short term measured response to rewetting events. The temperature sensitivity, measured using a Q10 function, was close to 2 for all soil cores, regardless of soil depth or (steady state) moisture content. The exclusion of fluxes collected following precipitation events from field-derived estimates of CO2 flux-temperature relationships, improved these relationships. This study provides insights into how we consider the role of moisture in evaluating SOM decomposition-temperature responses for temperate forest soils. © 2013 Elsevier Ltd.
Nams V.O.,Dalhousie University
Ecology Letters | Year: 2014
Animal movement paths show variation in space caused by qualitative shifts in behaviours. I present a method that (1) uses both movement path data and ancillary sensor data to detect natural breakpoints in animal behaviour and (2) groups these segments into different behavioural states. The method can also combine analyses of different path segments or paths from different individuals. It does not assume any underlying movement mechanism. I give an example with simulated data. I also show the effects of random variation, # of states and # of segments on this method. I present a case study of a fisher movement path spanning 8 days, which shows four distinct behavioural states divided into 28 path segments when only turning angles and speed were considered. When accelerometer data were added, the analysis shows seven distinct behavioural states divided into 41 path segments. © 2014 John Wiley & Sons Ltd/CNRS.
Murphy J.P.,Dalhousie University
Proteomics | Year: 2010
Dysregulation of the insulin-like growth factor 1 receptor signalling network is implicated in tumour growth and resistance to chemotherapy. We explored proteomic changes resulting from insulin-like growth factor 1 stimulation of MCF-7 adenocarcinoma cells as a function of time. Quantitative analysis using iTRAQ reagents and 2-D LC-MS/MS analysis of three biological replicates resulted in the identification of 899 proteins (p
Brunet T.D.P.,Dalhousie University
Journal of Biotechnology | Year: 2016
Applications of biotechnology to information security are now possible and have potentially far reaching political and technological implications. This change in information security practices, initiated by advancements in molecular biological and biotechnology, warrants reasonable and widespread consideration by biologists, biotechnologists and philosophers. I offer an explication of the landmark contributions, developments and current possibilities of biosteganography-the process of transmitting secure messages via biological mediums. I address, (i) how information can be stored and encoded in biological mediums, (ii) how biological mediums (e.g. DNA, RNA, protein) and storage systems (e.g. cells, biofilms, organisms) influence the nature of information security, and (iii) what constitutes a viable application of such biotechnologies. © 2016 Elsevier B.V.
Weerasinghe S.,Dalhousie University
Environmetrics | Year: 2010
Environmental data contains lengthy records of sequential missing values. Practical problem arose in the analysis of adverse health effects of sulphur dioxide (SO2) levels and asthma hospital admissions for Sydney, Nova Scotia, Canada. Reliable missing values imputation techniques are required to obtain valid estimates of the associations with sparse health outcomes such as asthma hospital admissions. In this paper, a new method that incorporates prediction errors to impute missing values is described using mean daily average sulphur dioxide levels following a stationary time series with a random error. Existing imputation methods failed to incorporate the prediction errors. An optimal method is developed by extending a between forecast method to include prediction errors. Validity and efficacy are demonstrated comparing the performances with the values that do not include prediction errors. The performances of the optimal method are demonstrated by increased validity and accuracy of the β coefficient of the Poisson regression model for the association with asthma hospital admissions. Visual inspection of the imputed values of sulphur dioxide levels with prediction errors demonstrated that the variation is better captured. The method is computationally simple and can be incorporated into the existing statistical software. © 2009 John Wiley & Sons, Ltd.
Croskerry P.,Dalhousie University
Academic Medicine | Year: 2011
Test ordering is an integral part of clinical decision making. Variation in test-ordering behavior appears to reflect uncertainty in the clinical reasoning and decision-making process. Among decision makers, novices function mostly in the analytic mode of reasoning, experiencing high levels of uncertainty and, therefore, account for the most variance. While less discriminate test ordering has both economical and clinical downsides, it nevertheless remains a rite of passage along the road toward expertise.In response to the article by Iwashyna and colleagues, the author of this commentary reflects on the implications of test-ordering behavior in the academic medicine setting. The process of ordering tests can serve purposes other than the obvious, not the least of which allows the decision maker additional time for reflection in the decision-making process, perhaps leading to a less mindless and more mindful approach.The author observes that test-ordering behavior of novitiates might be optimized through a variety of strategies that improve both active and passive learning in the clinical environment. In addition to specific education around costs, as well as Bayesian considerations, active learning importantly requires exposure to those processes that may subvert clinical reasoning, notably cognitive biases. Passive learning is enhanced in supportive environments. Throughout, those who supervise and teach should provide effective models. Copyright © by the Association of American Medical Colleges.
Pelletier N.,Dalhousie University
Ecological Economics | Year: 2010
The ecological economic concern with environmental sustainability embodies the normative orientations of the field. This concern is foremost a matter of distributive justice, the definition of which determines the relevance of the appropriate scale and efficient allocation criteria. Yet it would appear that the discipline lacks a shared, internally consistent set of ethical premises by which this concern might be legitimized. Various authors have embraced a Rawlsian conception of liberal justice as the appropriate banner for ecological economics in place of the consequentialist-libertarian foundations of neoclassical economics (including environmental economics). It is argued here that this is insufficient in so far as it is premised on a vision of a discrete, self-sufficient economic actor. Instead, it is posited that an ecological economic ethic must proceed from an understanding of the economic actor as community member - a recognition implicit in recent ecological economic contributions focused on discourse ethics and deliberative democracy. An ecological communitarian conception of distributive justice, which views the well-being of the individual as inseparable from the integrity of its implicate, mutually constituting human and non-human natural communities, is advanced as the appropriate basis for the ecological economic world-view. In this light, the thermodynamic foundations of ecological economics are seen to provide the necessary departure point for normative decision-making oriented towards ensuring sustainability in economic organization. © 2010 Elsevier B.V.
Ungar M.,Dalhousie University |
Ghazinour M.,Umea Sweden |
Richter J.,University of Rostock
Journal of Child Psychology and Psychiatry and Allied Disciplines | Year: 2013
Background: The development of Bronfenbrenner's bio-social-ecological systems model of human development parallels advances made to the theory of resilience that progressively moved from a more individual (micro) focus on traits to a multisystemic understanding of person-environment reciprocal processes. Methods: This review uses Bronfenbrenner's model and Ungar's social-ecological interpretation of four decades of research on resilience to discuss the results of a purposeful selection of studies of resilience that have been done in different contexts and cultures. Results: An ecological model of resilience can, and indeed has been shown to help researchers of resilience to conceptualize the child's social and physical ecologies, from caregivers to neighbourhoods, that account for both proximal and distal factors that predict successful development under adversity. Three principles emerged from this review that inform a bio-social-ecological interpretation of resilience: equifinality (there are many proximal processes that can lead to many different, but equally viable, expressions of human development associated with well-being); differential impact (the nature of the risks children face, their perceptions of the resources available to mitigate those risks and the quality of the resources that are accessible make proximal processes more or less influential to children's development); and contextual and cultural moderation (different contexts and cultures provide access to different processes associated with resilience as it is defined locally). Conclusion: As this review shows, using this multisystemic social-ecological theory of resilience can inform a deeper understanding of the processes that contribute to positive development under stress. It can also offer practitioners and policy makers a broader perspective on principles for the design and implementation of effective interventions. © 2012 The Authors. Journal of Child Psychology and Psychiatry © 2012 Association for Child and Adolescent Mental Health.
Blake J.T.,Dalhousie University
Transfusion | Year: 2013
Background: Canadian Blood Services runs approximately 16,000 donor clinics annually. While there were more than 220 different clinic configurations used in 2011 and 2012, 67% of all clinic configurations followed one of 51 standard models. As part of operational planning for current and future configurations it was necessary for Canadian Blood Services to calculate staffing requirements for standard clinic models. Study Design and Methods: In this article we present a method that incorporates both cost control and impact on donor experience. We calculate staffing requirements to minimize costs, but adjust using queuing theory to ensure donor wait time metrics are met. The method can be applied in a wide variety of situations. Results: Although developed for a particular study, the methods described in this article can be applied in a wide variety of situations. A case study in which the model is used to review existing staffing arrangements at Canadian Blood Services is presented. Conclusion: The staffing model can be used to balance the requirements of minimizing staffing costs with that of ensuring that donors do not suffer unnecessary delays. Moreover, in an example application, savings of 3.4% were identified through the modeling process. © 2013 American Association of Blood Banks.
Becke A.D.,Dalhousie University
Journal of Chemical Physics | Year: 2013
In recent papers [A. D. Becke, J. Chem. Phys. 138, 074109 (2013); 138, 161101 (2013)], a density functional for strong correlations in quantum chemistry was introduced. The functional is designed to capture molecular dissociation limits using symmetry-restricted orbitals. Here we demonstrate that the functional describes, with good accuracy, two-determinant multi-reference states. The examples of this work involve 50/50 mixing of symmetry-equivalent Slater determinants at avoided crossings. We employ exactly-computed exchange and fractional spin-orbital occupancies. The connection with dissociated systems and single-determinant reference states is explained. © 2013 AIP Publishing LLC.
Becke A.D.,Dalhousie University
Journal of Chemical Physics | Year: 2013
In recent work [A. D. Becke, J. Chem. Phys. 138, 074109 (2013)10.1063/1.4790598], a suite of density functionals for static, dynamical, and strong correlation was introduced. The strong-correlation part is intended to describe dissociating chemical systems using symmetry-restricted orbitals, and was calibrated on spin- and spatially-symmetrized open-shell atoms of the first and second rows. This Communication extends the calibration of our functionals to transition-metal atoms by including all open-shell atoms through the third row. We find that the theory works well for transition-metal atoms also. The new concomitant parametrization will be applied to problems of chemical interest in upcoming work. © 2013 AIP Publishing LLC.
Pohlmann-Eden B.,Dalhousie University
Epilepsia | Year: 2011
The definitions of "first seizure" and "new-onset epilepsy" are arbitrary and rather simple for use to describe the beginning of a complex brain disease in which seizures are only one symptom. A diligent study of early stages in epilepsy including detailed clinical information, psychiatric comorbidities, sophisticated advanced neuroimaging, and timely functional brain tests may provide a better understanding of epileptogenesis. The goal will be to understand the process of evolution to chronic epilepsy and eventually to prevent refractory epilepsy. © 2011 International League Against Epilepsy.
Sherwin S.,Dalhousie University
Bioethics | Year: 2011
I reflect on the past, present, and future of the field of bioethics. In so doing, I offer a very situated overview of where bioethics has been, where it now is, where it seems to be going, where I think we could do better, and where I dearly hope the field will be heading. I also propose three ways of re-orienting our theoretic tools to guide us in a new direction: (1) adopt an ethics of responsibility; (2) explore the responsibilities of various kinds of actors and relationships among them; (3) expand the types of participants engaged in bioethics. © 2010 Blackwell Publishing Ltd.
Burrows M.,University of Cambridge |
Burrows M.,Dalhousie University
Journal of Experimental Biology | Year: 2013
The kinematics and jumping performance of treehoppers (Hemiptera, Auchenorrhyncha, Membracidae) were analysed from high speed images. The eight species analysed had an 11-fold range of body mass (3.8-41?mg) and a 2-fold range of body length (4.1-8.4?mm). Body shape was dominated by a prothoracic helmet that projected dorsally and posteriorly over the body, and in some species forwards to form a protruding horn. Jumping was propelled by rapid depression of the trochantera of the hindlegs. The hindlegs were only 30-60% longer than the front and middle legs, and 47-94% the length of the body in different species. They were slung beneath the body and moved together in the same plane. In preparation for a jump, the hindlegs were initially levated and rotated forwards so that the femora were pressed into indentations of the coxae. The tibiae were flexed about the femora and the tarsi were placed on the ground directly beneath the lateral edges of the abdomen. Movements of the front and middle legs adjusted the angle of the body relative to the ground, but for most treehoppers this angle was small, so that the body was almost parallel to the ground. The rapid depression of the hindlegs accelerated the body to take-off in 1.2ms in the lighter treehoppers and 3.7?ms in the heavier ones. Take-off velocities of 2.1-2.7ms-1 were achieved and were not correlated with body mass. In the best jumps, these performances involved accelerations of 560-2450?m?s-2 (g forces of 47-250), an energy expenditure of 13.5-101μJ, a power output of 12-32 mW and exerted a force of 9.5-29mN. The power output per mass of muscle far exceeds the maximum active contractile limit of normal muscle. Such requirements indicate that treehoppers must be using a power amplification mechanism in a catapult-like action. Some jumps were preceded by flapping movements of the wings, but the propulsive movements of the hindlegs were crucial in achieving take-off. © 2013. Published by The Company of Biologists Ltd.
Pelletier N.,Dalhousie University
Global Environmental Change | Year: 2010
The persistent failures of international environmental governance initiatives to halt the degradation of the global commons are directly linked to the implicit worldview and assumptions fueling the proliferation of industrial society. These include an instrumental conception on non-human nature, rampant materialism, technological optimism, and an expansionary economics premised on the axiomatic necessity of unconstrained growth. Permeating contemporary environmental governance regimes, it is argued that these premises are fundamentally incompatible with the requirements of environmental sustainability. Proceeding from the perspective of ecological economics, it is further argued that achieving environmental sustainability in industrial society requires foremost that we restructure and constrain the scale of economic activities relative to global biocapacity. It is concluded that a scale-based approach to governing the environmental commons, operationalized by a strong world environment organization, offers at least a partial solution to this conundrum. © 2009 Elsevier Ltd. All rights reserved.
Lynch M.E.,Dalhousie University |
Lynch M.E.,Pain Management Unit |
Ware M.A.,McGill University
Journal of Neuroimmune Pharmacology | Year: 2015
An updated systematic review of randomized controlled trials examining cannabinoids in the treatment of chronic non-cancer pain was conducted according to PRISMA guidelines for systematic reviews reporting on health care outcomes. Eleven trials published since our last review met inclusion criteria. The quality of the trials was excellent. Seven of the trials demonstrated a significant analgesic effect. Several trials also demonstrated improvement in secondary outcomes (e.g., sleep, muscle stiffness and spasticity). Adverse effects most frequently reported such as fatigue and dizziness were mild to moderate in severity and generally well tolerated. This review adds further support that currently available cannabinoids are safe, modestly effective analgesics that provide a reasonable therapeutic option in the management of chronic non-cancer pain. © 2015, Springer Science+Business Media New York.
Burger G.,University of Montreal |
Gray M.W.,Dalhousie University |
Forget L.,University of Montreal |
Lang B.F.,University of Montreal
Genome Biology and Evolution | Year: 2013
The most bacteria-like mitochondrial genome known is that of the jakobid flagellate Reclinomonas americana NZ. This genome also encodes the largest known gene set among mitochondrial DNAs (mtDNAs), including the RNA subunit of RNase P (transfer RNA processing), a reduced form of transfer-messenger RNA (translational control), and a four-subunit bacteria-like RNA polymerase, which in other eukaryotes is substituted by a nucleus-encoded, single-subunit, phage-like enzyme. Further, protein-coding genes are preceded by potential Shine-Dalgarno translation initiation motifs. Whether similarly ancestral mitochondrial characters also exist in relatives of R. americana NZ is unknown. Here, we report a comparative analysis of nine mtDNAs from five distant jakobid genera: Andalucia, Histiona, Jakoba, Reclinomonas, and Seculamonas. We find that Andalucia godoyi has an even larger mtDNA gene complement than R. americana NZ. The extra genes are rpl35 (a large subunit mitoribosomal protein) and cox15 (involved in cytochrome oxidase assembly), which are nucleus encoded throughout other eukaryotes. Andalucia cox15 is strikingly similar to its homolog in the free-living a-proteobacterium Tistrella mobilis. Similarly, a long, highly conserved gene cluster in jakobid mtDNAs, which is a clear vestige of prokaryotic operons, displays a gene ordermore closely resembling that in free-living a-proteobacteria than in Rickettsiales species. Although jakobid mtDNAs, overall, are characterized by bacteria-like features, they also display a few remarkably divergent characters, such as 30-tRNA editing in Seculamonas ecuadoriensis and genome linearization in Jakoba libera. Phylogenetic analysis with mtDNA-encoded proteins strongly supports monophyly of jakobids with Andalucia as the deepest divergence. However, it remains unclear which a-proteobacterial group is the closest mitochondrial relative. © 2012 The Author(s).
Reid L.,Dalhousie University
Perspectives in Biology and Medicine | Year: 2011
Conceptions of professionalism in medicine draw on social contract theory; its strengths and weaknesses play out in how we reason about professionalism. The social contract metaphor may be a heuristic device prompting reflection on social responsibility, and as such is appealing: it encourages reasoning about privilege and responsibility, the broader context and consequences of action, and diverse perspectives on medical practice.However,when this metaphor is elevated to the status of a theory, it has well-known limits: the assumed subject position of contractors engenders blind spots about privilege, not critical reflection; its tendency to dress up the status quo in the trappings of a theoretical agreement may limit social negotiation; its attempted reconciliation of social obligation and self-interest fosters the view that ethics and selfinterest should coincide; it sets up false expectations by identifying appearance and reality in morality; and its construal of prima facie duties as conditional misdirects ethical attention in particular situations from current needs to supposed past agreements or reciprocities. Using philosophical ideas as heuristic devices in medical ethics is inevitable, but we should be conscious of their limitations.When they limit the ethical scope of debate, we should seek new metaphors. © 2011 by The Johns Hopkins University Press.
Mahmoudi M.,Pasteur Institute of Iran |
Mahmoudi M.,Tehran University of Medical Sciences |
Azadmanesh K.,Pasteur Institute of Iran |
Shokrgozar M.A.,Pasteur Institute of Iran |
And 3 more authors.
Chemical Reviews | Year: 2011
A scientific review presents a broad overview of the effect of nanoparticles on the cell life cycle and their corresponding phase arresting the existing data. A comprehensive description of the available assays for probing the effect of nanoparticles on the cell life cycle is also presented. The cell cycle corresponds to a series of events which lead the cell to its division and duplication. The cell cycle can be divided into two brief periods in eukaryotes, such as the interphase during which the cell grows and accumulates nutrients needed for mitosis and DNA replication and the mitosis phase in which the cell splits itself into two distinct daughter cells. The mitosis phase corresponds to the actual cell division and requires significant amounts of energy. The final division is called cytokinesis after which the two daughter cells produced restart the cell cycle.
Shen Y.,China Three Gorges University |
Huang Y.,China Three Gorges University |
Gu J.,Dalhousie University
IEEE Transactions on Automatic Control | Year: 2011
This technical note presents a global finite-time observer design for a class of systems with Lipschitz nonlinearity. By applying a finite-time stability theorem and a careful selection of the homogeneity powers and weights, the problem of global and finite-time stable observers is studied. An observer design procedure is given and a numerical example is provided to illustrate the design method. © 2006 IEEE.
De Santo E.M.,Dalhousie University
Journal of Environmental Management | Year: 2013
International targets for marine protected areas (MPAs) and networks of MPAs set by the World Summit on Sustainable Development and United Nations Convention on Biological Diversity failed to meet their 2012 deadline and have been extended to 2020. Whilst targets play an important role in building momentum for conservation, they are also responsible for the recent designation of several extremely large no-take MPAs, which pose significant long-term monitoring and enforcement challenges. This paper critically examines the effectiveness of MPA targets, focusing on the underlying risks to achieving Millennium Development Goals posed by the global push for quantity versus quality of MPAs. The observations outlined in this paper have repercussions for international protected area politics with respect to (1) the science-policy interface in environmental decision-making, and (2) social justice concerns in global biodiversity conservation. © 2013 Elsevier Ltd.
Doyle L.,University of Prince Edward Island |
Mackay-Lyons M.,Dalhousie University
Journal of Neurologic Physical Therapy | Year: 2013
Background and purpose:: Although aerobic exercise (AE) has been shown to improve aerobic capacity and reduce morbidity in neurological populations, its application is challenging. The purpose of this study was to survey Canadian physical therapists practicing in adult neurorehabilitation regarding the use of AE in clinical practice. METHODS:: Members of the Neurosciences Division of the Canadian Physiotherapy Association were invited to participate in a Web-based survey. RESULTS:: Response rate was 36% (N = 155) with every Canadian province represented. The majority of respondents were females in full-time practice for more than 15 years. The majority (88%) agreed/strongly agreed with the following: "AE should be incorporated into treatment programs of patients with neurological conditions." Although 77% prescribed AE, barriers to use included patient concerns (cardiac status, cognitive/perceptual deficits, fatigue) and operations (lack of staff, time, screening tools). The most commonly used screening tools were health records and patient responses to exercise and the least common was exercise stress tests. Overground walking and cycle ergometry were the most frequently used AE modes, and general response to exercise and patient feedback were most frequently used for determining exercise intensity and monitoring AE. DISCUSSION AND CONCLUSIONS:: Respondents clearly recognized the importance of AE in neurorehabilitation. Barriers to application of AE and limitations in the use of appropriate screening and training procedures need to be addressed to advance clinical utilization of AE in neurological practice. Understanding current patterns of utilization of AE is important for the development of professional education initiatives and clinical guidelines for best practices in AE for neurological populations. © 2013 Neurology Section, APTA.
Unick G.J.,University of Maryland, Baltimore |
Rosenblum D.,Dalhousie University |
Mars S.,University of California at San Francisco |
Ciccarone D.,University of California at San Francisco
PLoS ONE | Year: 2013
The historical patterns of opiate use show that sources and methods of access greatly influence who is at risk. Today, there is evidence that an enormous increase in the availability of prescription opiates is fuelling a rise in addiction nationally, drawing in new initiates to these drugs and changing the geography of opiate overdoses. Recent efforts at supply-based reductions in prescription opiates may reduce harm, but addicted individuals may switch to other opiates such as heroin. In this analysis, we test the hypothesis that changes in the rates of Prescription Opiate Overdoses (POD) are correlated with changes in the rate of heroin overdoses (HOD). ICD9 codes from the Nationwide Inpatient Sample and population data from the Census were used to estimate overall and demographic specific rates of POD and HOD hospital admissions between 1993 and 2009. Regression models were used to test for linear trends and lagged negative binomial regression models were used to model the interrelationship between POD and HOD hospital admissions. Findings show that whites, women, and middle-aged individuals had the largest increase in POD and HOD rates over the study period and that HOD rates have increased in since 2007. The lagged models show that increases in a hospitals POD predict an increase in the subsequent years HOD admissions by a factor of 1.26 (p<0.001) and that each increase in HOD admissions increase the subsequent years POD by a factor of 1.57 (p<0.001). Our hypothesis of fungibility between prescription opiates and heroin was supported by these analyses. These findings suggest that focusing on supply-based interventions may simply lead to a shift in use to heroin rather minimizing the reduction in harm. The alternative approach of using drug abuse prevention resources on treatment and demand-side reduction is likely to be more productive at reducing opiate abuse related harm. © 2013 Unick et al.
Easton A.S.,Dalhousie University
Advances in experimental medicine and biology | Year: 2012
The blood-brain barrier refers to the very low permeability across microvessels in the Central Nervous System (CNS), created by the interaction between vascular endothelial cells and surrounding cells of the neurovascular unit. Permeability can be modulated (increased and decreased) by a variety of factors including inflammatory mediators, inflammatory cells such as neutrophils and through alterations in the phenotype of blood vessels during angiogenesis and apoptosis. In this chapter, some of these factors are discussed as well as the challenge of treating harmful increases in permeability that result in brain swelling (vasogenic cerebral edema).
Magera A.M.,Dalhousie University
PloS one | Year: 2013
Marine mammals have greatly benefitted from a shift from resource exploitation towards conservation. Often lauded as symbols of conservation success, some marine mammal populations have shown remarkable recoveries after severe depletions. Others have remained at low abundance levels, continued to decline, or become extinct or extirpated. Here we provide a quantitative assessment of (1) publicly available population-level abundance data for marine mammals worldwide, (2) abundance trends and recovery status, and (3) historic population decline and recent recovery. We compiled 182 population abundance time series for 47 species and identified major data gaps. In order to compare across the largest possible set of time series with varying data quality, quantity and frequency, we considered an increase in population abundance as evidence of recovery. Using robust log-linear regression over three generations, we were able to classify abundance trends for 92 spatially non-overlapping populations as Significantly Increasing (42%), Significantly Decreasing (10%), Non-Significant Change (28%) and Unknown (20%). Our results were comparable to IUCN classifications for equivalent species. Among different groupings, pinnipeds and other marine mammals (sirenians, polar bears and otters) showed the highest proportion of recovering populations, likely benefiting from relatively fast life histories and nearshore habitats that provided visibility and protective management measures. Recovery was less frequent among cetaceans, but more common in coastal than offshore populations. For marine mammals with available historical abundance estimates (n = 47), larger historical population declines were associated with low or variable recent recoveries so far. Overall, our results show that many formerly depleted marine mammal populations are recovering. However, data-deficient populations and those with decreasing and non-significant trends require attention. In particular, increased study of populations with major data gaps, including offshore small cetaceans, cryptic species, and marine mammals in low latitudes and developing nations, is needed to better understand the status of marine mammal populations worldwide.
Darnell S.C.,Dalhousie University
Sociology of Sport Journal | Year: 2010
Sport is currently mobilized as a tool of international development within the "Sport for Development and Peace" (SDP) movement. Framed by Gramscian hegemony theory and sport and development studies respectively, this article offers an analysis of the conceptualization of sport's social and political utility within SDP programs. Drawing on the perspectives of young Canadians (n = 27) who served as volunteer interns within Commonwealth Games Canada's International Development through Sport program, the dominant ideologies of development and social change that underpin current SDP practices are investigated. The results suggest that while sport does offer a new and unique tool that successfully aligns with a development mandate, the logic of sport is also compatible with the hegemony of neo-liberal development philosophy. As a result, careful consideration of the social politics of sport and development within the SDP movement is called for. © 2010 Human Kinetics, Inc.
The freedom to explore: Examining the influence of independent mobility on weekday, weekend and after-school physical activity behaviour in children living in urban and inner-suburban neighbourhoods of varying socioeconomic status
Stone M.R.,Dalhousie University |
Faulkner G.E.J.,University of Toronto |
Mitra R.,Ryerson University |
Buliung R.N.,University of Toronto
International Journal of Behavioral Nutrition and Physical Activity | Year: 2014
Background: Children's independent mobility (CIM) is critical to healthy development in childhood. The physical layout and social characteristics of neighbourhoods can impact opportunities for CIM. While global evidence is mounting on CIM, to the authors' knowledge, Canadian data on CIM and related health outcomes (i.e., physical activity (PA) behaviour) are missing. The purpose of this study was to examine if CIM is related to multiple characteristics of accelerometry-measured PA behaviour (total PA, light PA, moderate-to-vigorous PA, time spent sedentary) and whether associations between CIM and PA behaviour systematically vary by place of residence, stratifying by gender and type of day/period (weekdays, after-school, weekend).Methods: Participants were recruited through Project BEAT (Built Environment and Active Transport; http://www.beat.utoronto.ca). Children (n = 856) were stratified into four neighbourhood classifications based on the period of neighbourhood development (urban built environment (BE) (old BE) versus inner-suburban BE (new BE)) and socioeconomic status (SES; low SES and high SES). Physical activity was measured via accelerometry (ActiGraph GT1M). CIM was assessed via parental report and two categories were created (low CIM, n = 332; high CIM, n = 524). A series of two-factor ANOVAs were used to determine gender-specific differences in PA for weekdays, weekend days and the after-school period, according to level of CIM, across four neighbourhood classifications.Results: Children who were granted at least some independent mobility (high CIM) had more positive PA profiles across the school week, during the after-school period, and over the weekend; they were also less sedentary. The influence of CIM on PA behaviour was particularly salient during the after-school period. Associations of CIM with PA varied by gender, and also by neighbourhood classification. CIM seemed to matter more in urban neighbourhoods for boys and suburban neighbourhoods for girls.Conclusion: Our findings highlight the importance of independent mobility to multiple characteristics of children's PA behaviour across the week. Furthermore, they emphasize that independent mobility-activity relationships need to be considered by gender and the type of neighbourhood independent mobility is offered in. Future work will focus on developing a predictive model of CIM that could be used to inform decision-making around alleviating barriers to CIM. © 2014 Stone et al.; licensee BioMed Central Ltd.
Bogachev O.,Dalhousie University
Molecular medicine (Cambridge, Mass.) | Year: 2011
Atherogenesis is a long-term process that involves inflammatory response coupled with metabolic dysfunction. Foam cell formation and macrophage inflammatory response are two key events in atherogenesis. Adipocyte enhancer-binding protein 1 (AEBP1) has been shown to impede macrophage cholesterol efflux, promoting foam cell formation, via peroxisome proliferator-activated receptor (PPAR)-γ1 and liver X receptor α (LXRα) downregulation. Moreover, AEBP1 has been shown to promote macrophage inflammatory responsiveness by inducing nuclear factor (NF)-κB activity via IκBα downregulation. Lipopolysaccharide (LPS)-induced suppression of pivotal macrophage cholesterol efflux mediators, leading to foam cell formation, has been shown to be mediated by AEBP1. Herein, we showed that AEBP1-transgenic mice (AEBP1(TG)) with macrophage-specific AEBP1 overexpression exhibit hyperlipidemia and develop atherosclerotic lesions in their proximal aortas. Consistently, ablation of AEBP1 results in significant attenuation of atherosclerosis (males: 3.2-fold, P = 0.001 [en face]), 2.7-fold, P = 0.0004 [aortic roots]; females: 2.1-fold, P = 0.0026 [en face], 1.7-fold, P = 0.0126 [aortic roots]) in the AEBP1(-/-)/low-density lipoprotein receptor (LDLR )(-/-) double-knockout (KO) mice. Bone marrow (BM) transplantation experiments further revealed that LDLR (-/-) mice reconstituted with AEBP1(-/-)/LDLR (-/-) BM cells (LDLR (-/-)/KO-BM chimera) display significant reduction of atherosclerosis lesions (en face: 2.0-fold, P = 0.0268; aortic roots: 1.7-fold, P = 0.05) compared with control mice reconstituted with AEBP1(+/+)/LDLR (-/-) BM cells (LDLR (-/-)/WT-BM chimera). Furthermore, transplantation of AEBP1(TG) BM cells with the normal apolipoprotein E (ApoE) gene into ApoE (-/-) mice (ApoE (-/-)/TG-BM chimera) leads to significant development of atherosclerosis (males: 2.5-fold, P = 0.0001 [en face], 4.7-fold, P = 0.0001 [aortic roots]; females: 1.8-fold, P = 0.0001 [en face], 3.0-fold, P = 0.0001 [aortic roots]) despite the restoration of ApoE expression. Macrophages from ApoE (-/-)/TG-BM chimeric mice express reduced levels of PPARγ1, LXRα, ATP-binding cassette A1 (ABCA1) and ATP-binding cassette G1 (ABCG1) and increased levels of the inflammatory mediators interleukin (IL)-6 and tumor necrosis factor (TNF)-α compared with macrophages of control chimeric mice (ApoE (-/-)/NT-BM ) that received AEBP1 nontransgenic (AEBP1(NT) ) BM cells. Our in vivo experimental data strongly suggest that macrophage AEBP1 plays critical regulatory roles in atherogenesis, and it may serve as a potential therapeutic target for the prevention or treatment of atherosclerosis.
Noel M.,Dalhousie University
Journal of pediatric psychology | Year: 2010
OBJECTIVE: To examine whether children's experience of pain intensity and anxiety, and adult behaviors during venepuncture, were related to children's memories of the procedure. METHODS: Participants were 48 children (24 males, 24 females) between the ages of 5 and 10 years who underwent venepuncture. The venepunctures were videotaped and adult behaviors were coded. Children self-reported their pain intensity and anxiety immediately and 2 weeks following venepuncture and answered contextual questions at follow-up. RESULTS: Children who initially reported higher levels of pain tended to over-estimate their anxiety at follow-up, whereas children who reported lower levels of pain accurately- or under-estimated their anxiety. Staff coping-promoting behaviors predicted the accuracy of children's contextual memories. Staff and parent behaviors did not predict children's recalled pain intensity and anxiety. CONCLUSIONS: Results indicate that children's direct experience of pain intensity and staff behaviors during venepuncture are related to their memories. These data highlight the importance of effective pain management during medical procedures.
Borgerson K.,Dalhousie University
Theoretical Medicine and Bioethics | Year: 2013
Most phase III clinical trials today are explanatory. Because explanatory, or efficacy, trials test hypotheses under "ideal" conditions, they are not well suited to providing guidance on decisions made in most clinical care contexts. Pragmatic trials, which test hypotheses under "usual" conditions, are often better suited to this task. Yet, pragmatic, or effectiveness, trials are infrequently carried out. This mismatch between the design of clinical trials and the needs of health care professionals is frustrating for everyone involved, and explains some of the challenges inherent in attempts to enhance knowledge translation and encourage evidence-based practice. The situation is more than simply frustrating, however; it is potentially unethical. Clinical trials must be socially valuable in order to (1) warrant the risks they impose on human research subjects and (2) fairly and efficiently assess new clinical interventions. Most bioethicists would agree that trials that have no social value, for instance, because their results do not have the potential to advance clinical care, should not be performed. What is less widely appreciated is that given limited research resources, trials that are more socially valuable should be preferred to trials that are less socially valuable when all else is equal. With respect to clinical trial design, I argue that while explanatory trials often have some social value, many have less social value than their pragmatic counterparts. On the basis of this general ethical assessment, I provide a preliminary defense of the position that clinical researchers should aim to conduct pragmatic trials, that is, that researchers face a burden of justification related to any idealizing elements added to trial designs. © 2013 Springer Science+Business Media Dordrecht.
Lynch M.E.,Dalhousie University |
Campbell F.,University of Toronto
British Journal of Clinical Pharmacology | Year: 2011
Effective therapeutic options for patients living with chronic pain are limited. The pain relieving effect of cannabinoids remains unclear. A systematic review of randomized controlled trials (RCTs) examining cannabinoids in the treatment of chronic non-cancer pain was conducted according to the PRISMA statement update on the QUORUM guidelines for reporting systematic reviews that evaluate health care interventions. Cannabinoids studied included smoked cannabis, oromucosal extracts of cannabis based medicine, nabilone, dronabinol and a novel THC analogue. Chronic non-cancer pain conditions included neuropathic pain, fibromyalgia, rheumatoid arthritis, and mixed chronic pain. Overall the quality of trials was excellent. Fifteen of the eighteen trials that met the inclusion criteria demonstrated a significant analgesic effect of cannabinoid as compared with placebo and several reported significant improvements in sleep. There were no serious adverse effects. Adverse effects most commonly reported were generally well tolerated, mild to moderate in severity and led to withdrawal from the studies in only a few cases. Overall there is evidence that cannabinoids are safe and modestly effective in neuropathic pain with preliminary evidence of efficacy in fibromyalgia and rheumatoid arthritis. The context of the need for additional treatments for chronic pain is reviewed. Further large studies of longer duration examining specific cannabinoids in homogeneous populations are required. © 2011 The Authors. British Journal of Clinical Pharmacology © 2011 The British Pharmacological Society.
Zwanziger J.W.,Dalhousie University
Physics and Chemistry of Glasses: European Journal of Glass Science and Technology Part B | Year: 2012
Several issues raised by the recent discovery of compounds with four-fold coordinate boron in edge-shared pairs are addressed by means of first principles computations. First, site-specific assignments are made by computing the quadrupole coupling of each boron and comparing literature values. Then, the bonding contacts in this unusual arrangement are studied through the atoms-in-molecules approach. Finally, the unusual three-fold coordinate oxygen in another high pressure borate phase is studied in the same way. All computations were performed using the projector-augmented wave formalism.
Ford Doolittle W.,Dalhousie University
Cold Spring Harbor Perspectives in Biology | Year: 2014
Systematics balances uneasily between realism and nominalism, uncommitted as to whether biological taxa are discoveries or inventions. If the former, they might be taken as natural kinds. I briefly review some philosophers' concepts of natural kinds and then argue that several of these apply well enough to "eukaryote." Although there are some sticky issues around genomic chimerism and when eukaryotes first appeared, if we allow for degrees in the naturalness of kinds, existing eukaryotes rank highly, higher than prokaryotes. Most biologists feel this intuitively: All I attempt to do here is provide some conceptual justification. © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.
Zhao H.,Jilin University |
Zhang B.-L.,Jilin University |
Yang S.-J.,Jilin University |
Rusak B.,Dalhousie University
Behavioural Brain Research | Year: 2015
Serotonergic neurons in the dorsal raphe nucleus (DRN) play an important role in regulation of many physiological functions. The lateral nucleus of the habenula