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Showing papers by "Dalhousie University published in 2004"


Journal ArticleDOI
08 Apr 2004-Nature
TL;DR: Results indicate that haematopoietic stem cells do not readily acquire a cardiac phenotype, and raise a cautionary note for clinical studies of infarct repair.
Abstract: The mammalian heart has a very limited regenerative capacity and, hence, heals by scar formation. Recent reports suggest that haematopoietic stem cells can transdifferentiate into unexpected phenotypes such as skeletal muscle, hepatocytes, epithelial cells, neurons, endothelial cells and cardiomyocytes, in response to tissue injury or placement in a new environment. Furthermore, transplanted human hearts contain myocytes derived from extra-cardiac progenitor cells, which may have originated from bone marrow. Although most studies suggest that transdifferentiation is extremely rare under physiological conditions, extensive regeneration of myocardial infarcts was reported recently after direct stem cell injection, prompting several clinical trials. Here, we used both cardiomyocyte-restricted and ubiquitously expressed reporter transgenes to track the fate of haematopoietic stem cells after 145 transplants into normal and injured adult mouse hearts. No transdifferentiation into cardiomyocytes was detectable when using these genetic techniques to follow cell fate, and stem-cell-engrafted hearts showed no overt increase in cardiomyocytes compared to sham-engrafted hearts. These results indicate that haematopoietic stem cells do not readily acquire a cardiac phenotype, and raise a cautionary note for clinical studies of infarct repair.

2,239 citations


Journal ArticleDOI
TL;DR: In this paper, the authors describe the development of a short, general measure of experiential avoidance, based on a specific theoretical approach to this process, which is incorporated into Acceptance and Commitment Therapy.
Abstract: The present study describes the development of a short, general measure of experiential avoidance, based on a specific theoretical approach to this process. A theoretically driven iterative exploratory analysis using structural equation modeling on data from a clinical sample yielded a single factor comprising 9 items. A fully confirmatory factor analysis upheld this same 9-item factor in an independent clinical sample. The operational characteristics of the Acceptance and Action Questionnaire (AAQ) were then examined in 8 additional samples. All totaled, over 2,400 participants were studied. As expected, higher levels of experiential avoidance were associated with higher levels of general psychopathology, depression, anxiety, a variety of specific fears, trauma, and a lower quality of life. The AAQ related to more specific measures of avoidant coping and to self-deceptive positivity, but the relation to psychopathology could not be fully accounted for by these alternative measures. The data provide some initial support for the model of experiential avoidance based on Relational Frame Theory that is incorporated into Acceptance and Commitment Therapy, and provides researchers with a preliminary measure for use in population-based studies on experiential avoidance.

1,879 citations


Journal ArticleDOI
TL;DR: It appears, therefore, that controlled processing is carried out more effectively by bilinguals and that bilingualism helps to offset age-related losses in certain executive processes.
Abstract: Previous work has shown that bilingualism is associated with more effective controlled processing in children; the assumption is that the constant management of 2 competing languages enhances executive functions (E. Bialystok, 2001). The present research attempted to determine whether this bilingual advantage persists for adults and whether bilingualism attenuates the negative effects of aging on cognitive control in older adults. Three studies are reported that compared the performance of monolingual and bilingual middle-aged and older adults on the Simon task. Bilingualism was associated with smaller Simon effect costs for both age groups; bilingual participants also responded more rapidly to conditions that placed greater demands on working memory. In all cases the bilingual advantage was greater for older participants. It appears, therefore, that controlled processing is carried out more effectively by bilinguals and that bilingualism helps to offset age-related losses in certain executive processes.

1,401 citations


Journal ArticleDOI
01 Sep 2004-Ecology
TL;DR: A change in approach is needed to determine whether pollen limitation reflects random fluctuations around a pollen–resource equilibrium, an adaptation to stochastic pollination environments, or a chronic syndrome caused by an environmental perturbation.
Abstract: Determining whether seed production is pollen limited has been an area of intensive empirical study over the last two decades. Yet current evidence does not allow satisfactory assessment of the causes or consequences of pollen limitation. Here, we critically evaluate existing theory and issues concerning pollen limitation. Our main conclusion is that a change in approach is needed to determine whether pollen limitation reflects random fluctuations around a pollen–resource equilibrium, an adaptation to stochastic pollination environments, or a chronic syndrome caused by an environmental perturbation. We formalize and extend D. Haig and M. Westoby's conceptual model, and illustrate its use in guiding research on the evolutionary consequences of pollen limitation, i.e., whether plants evolve or have evolved to ameliorate pollen limitation. This synthesis also reveals that we are only beginning to understand when and how pollen limitation at the plant level translates into effects on plant population dynamics...

1,128 citations


Journal ArticleDOI
TL;DR: In this article, an in situ X-ray diffraction study of the reaction of lithium with a-Si has been performed, and the results confirm that a new crystalline Li 15 Si 4 phase is formed below 30 mV as Li/Li + as first reported by Obrovac and Christensen in an article published in Electrochemical and Solid-State Letters.
Abstract: Silicon is a very promising candidate to replace graphite as the anode in Li-ion batteries because of its very high theoretical capacity. It has not yet made its way into commercial cells because of severe problems with the charge and discharge cycling of the material. It seems that amorphous silicon and amorphous silicon-containing alloys exhibit much improved cycling performance. Therefore, it is desirable to fully understand the reaction of Li with a-Si. To this end, an in situ X-ray diffraction study of the reaction of lithium with a-Si has been performed. The results confirm that a new crystalline Li 15 Si 4 phase is formed below 30 mV as Li/Li + as first reported by Obrovac and Christensen in an article published in Electrochemical and Solid-State Letters. However, the crystalline phase only forms for films of a-Si above a critical thickness of about 2 μm.

991 citations


Journal ArticleDOI
TL;DR: Studies of this intriguing immune-effector cell provide important insights into the complex mechanisms by which appropriate innate and acquired immune responses are initiated.
Abstract: Mast cells have mainly been studied in the setting of allergic disease, but the importance of mast cells for host defence against several pathogens has now been well established. The location of mast cells, which are found closely associated with blood vessels, allows them to have a crucial sentinel role in host defence. The mast cell has a unique 'armamentarium' of receptor systems and mediators for responding to pathogen-associated signals. Studies of this intriguing immune-effector cell provide important insights into the complex mechanisms by which appropriate innate and acquired immune responses are initiated.

809 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the probability of failure of a cohesive slope using both simple and more advanced probabilistic analysis tools, and concluded that simplified probabilism, in which spatial variability is ignored by assuming perfect correlation, can lead to unconservative estimates of the failure probability.
Abstract: In this paper we investigate the probability of failure of a cohesive slope using both simple and more advanced probabilistic analysis tools. The influence of local averaging on the probability of failure of a test problem is thoroughly investigated. In the simple approach, classical slope stability analysis techniques are used, and the shear strength is treated as a single random variable. The advanced method, called the random finite-element method (RFEM), uses elastoplasticity combined with random field theory. The RFEM method is shown to offer many advantages over traditional probabilistic slope stability techniques, because it enables slope failure to develop naturally by “seeking out” the most critical mechanism. Of particular importance in this work is the conclusion that simplified probabilistic analysis, in which spatial variability is ignored by assuming perfect correlation, can lead to unconservative estimates of the probability of failure. This contradicts the findings of other investigators w...

794 citations


Journal ArticleDOI
TL;DR: It is proposed that SKPs represent an endogenous embryonic precursor cell that arises in peripheral tissues such as skin during development and maintains multipotency into adulthood.
Abstract: A fundamental question in stem cell research is whether cultured multipotent adult stem cells represent endogenous multipotent precursor cells. Here we address this question, focusing on SKPs, a cultured adult stem cell from the dermis that generates both neural and mesodermal progeny. We show that SKPs derive from endogenous adult dermal precursors that exhibit properties similar to embryonic neural-crest stem cells. We demonstrate that these endogenous SKPs can first be isolated from skin during embryogenesis and that they persist into adulthood, with a niche in the papillae of hair and whisker follicles. Furthermore, lineage analysis indicates that both hair and whisker follicle dermal papillae contain neural-crest-derived cells, and that SKPs from the whisker pad are of neural-crest origin. We propose that SKPs represent an endogenous embryonic precursor cell that arises in peripheral tissues such as skin during development and maintains multipotency into adulthood.

761 citations


Journal ArticleDOI
TL;DR: Data from more than 230 populations reveal a median reduction of 83% in breeding population size from known historic levels, drawing attention to scientists' limited understanding of how fish behavior, habitat, ecology, and evolution affect population growth at low abundance.
Abstract: Rapid declines threaten the persistence of many marine fish. Data from more than 230 populations reveal a median reduction of 83% in breeding population size from known historic levels. Few populations recover rapidly; most exhibit little or no change in abundance up to 15 years after a collapse. Reductions in fishing pressure, although clearly necessary for population recovery, are often insufficient. Persistence and recovery are also influenced by life history, habitat alteration, changes to species assemblages, genetic responses to exploitation, and reductions in population growth attributable to the Allee effect, also known as depensation. Heightened extinction risks were highlighted recently when a Canadian population of Atlantic cod (Gadus morhua) was listed as endangered, on the basis of declines as high as 99.9% over 30 years. Unprecedented reductions in abundance and surprisingly low rates of recovery draw attention to scientists' limited understanding of how fish behavior, habitat, ecol...

711 citations


Journal ArticleDOI
TL;DR: It is concluded that QFASA provides estimates of diets for individuals at time scales that are relevant to the ecological processes affecting survival, and can be used to study diet variability within individuals over time, which will provide important opportunities rarely possible with other indirect methods.
Abstract: Accurate estimates of the diets of predators are required in many areas of ecology, but for many species current methods are imprecise, limited to the last meal, and often biased. The diversity of fatty acids and their patterns in organisms, coupled with the narrow limitations on their biosynthesis, properties of digestion in monogastric animals, and the prevalence of large storage reservoirs of lipid in many predators, led us to propose the use of quantitative fatty acid signature analysis (QFASA) to study predator diets. We present a statistical model that provides quantitative estimates of the proportions of prey species in the diets of individual predators using fatty acid signatures. We conducted simulation studies using a database of 28 prey species (n = 954 individuals) from the Scotian Shelf off eastern Canada to investigate properties of the model and to evaluate the reliability with which prey could be distinguished in the model. We then conducted experiments on grey seals (Halichoerus grypus, n = 25) and harp seals (Phoca groenlandica, n = 5) to assess quantitative characteristics of fatty acid deposition and to develop calibration coefficients for individual fatty acids to account for predator lipid metabolism. We then tested the model and calibration coefficients by estimating the diets of experimentally fed captive grey seals (n = 6, switched from herring to a mackerel/capelin diet) and mink kits (Mustela vison, n = 46, switched from milk to one of three oil-supplemented diets). The diets of all experimentally fed animals were generally well estimated using QFASA and were consistent with qualitative and quantitative expectations, provided that appropriate calibration coefficients were used. In a final case, we compared video data of foraging by individual free- ranging harbor seals (Phoca vitulina, n = 23) fitted with Crittercams and QFASA estimates of the diet of those same seals using a complex ecosystem-wide prey database. Among the 28 prey species in the database, QFASA estimated sandlance to be the dominant prey species in the diet of all seals (averaging 62% of diet), followed primarily by flounders, but also capelin and minor amounts of other species, although there was also considerable individual variability among seals. These estimates were consistent with video data showing sandlance to be the predominant prey, followed by flatfish. We conclude that QFASA provides estimates of diets for individuals at time scales that are relevant to the ecological processes affecting survival, and can be used to study diet variability within individuals over time, which will provide important opportunities rarely possible with other indirect methods. We propose that the QFASA model we have set forth will be applicable to a wide range of predators and ecosystems.

677 citations


Proceedings ArticleDOI
06 Nov 2004
TL;DR: A comprehensive picture of the role of tabletop territoriality in collaboration is provided with a synthesis of the findings and previous research findings and with several relevant design implications.
Abstract: Researchers seeking alternatives to traditional desktop computers have begun exploring the potential collaborative benefits of digital tabletop displays. However, there are still many open issues related to the design of collaborative tabletop interfaces, such as whether these systems should automatically orient workspace items or enforce ownership of workspace content. Understanding the natural interaction practices that people use during tabletop collaboration with traditional media (e.g., pen and paper) can help to address these issues. Interfaces that are modeled on these practices will have the additional advantage of supporting the interaction skills people have developed over years of collaborating at traditional tables. To gain a deeper understanding of these interaction practices we conducted two observational studies of traditional tabletop collaboration in both casual and formal settings. Our results reveal that collaborators use three types of tabletop territories to help coordinate their interactions within the shared tabletop workspace: personal, group, and storage territories. Findings from a spatial analysis of collaborators' tabletop interactions reveal important properties of these tabletop territories. In order to provide a comprehensive picture of the role of tabletop territoriality in collaboration, we conclude with a synthesis of our findings and previous research findings and with several relevant design implications.

Journal ArticleDOI
TL;DR: A constructionist interpretation of resilience reflects a postmodern understanding of the construct that better accounts for cultural and contextual differences in how resilience is expressed by individuals, families, and communities as mentioned in this paper.
Abstract: An ecological approach to the study of resilience, informed by Systems Theory and emphasizing predictable relationships between risk and protective factors, circular causality, and transactional processes, is inadequate to account for the diversity of people’s experiences of resilience. In contrast, a constructionist interpretation of resilience reflects a postmodern understanding of the construct that better accounts for cultural and contextual differences in how resilience is expressed by individuals, families, and communities. Research supporting this approach has demonstrated a nonsystemic, nonhierarchical relationship between risk and protective factors that is characteristically chaotic, complex, relative, and contextual. This article critically reviews research findings that support an ecological perspective and explores the emerging literature that informs a constructionist approach to the study of resilience. It will show that an alternate constructionist discourse on resilience greatly enhances ...

Journal ArticleDOI
TL;DR: In this article, a thermal-mechanical numerical model was used to examine the development of mid-crustal channel flows in large hot orogens, where radioactive self-heating reduces the viscosity of tectonically thickened crust and increases its susceptibility to large-scale horizontal flow.
Abstract: [1] Plane strain, thermal-mechanical numerical models are used to examine the development of midcrustal channel flows in large hot orogens. In the models, radioactive self-heating reduces the viscosity of tectonically thickened crust and increases its susceptibility to large-scale horizontal flow. Channels can be exhumed and exposed by denudation focused on the high-relief transition between plateau and foreland. We interpret the Himalaya to have evolved in this manner. Channel flows are poorly developed if the channel has a ductile rheology based on wet quartz flow laws, and well developed if there is an additional reduction in viscosity to 1019 Pa s. This reduction occurs from 700°C to 750°C in the models and is attributed to a small percentage of in situ partial melt (“melt weakening”). Model HT1 provides an internally consistent explanation for the tectonic evolution of many features of the Himalayan-Tibetan orogenic system. Erosional exhumation exposes the migmatitic channel, equivalent to the Greater Himalayan Sequence (GHS), between coeval normal and thrust sense ductile shear zones, corresponding to the South Tibetan Detachment and the Main Central Thrust systems. Outward flow of unstable upper crust rotates these shears to low dip angles. In the model both the GHS and the Lesser Himalayan Sequence are derived from Indian crust, with the latter from much farther south. Similar models exhibit a range of tectonic styles, including the formation of domes resembling north Himalayan gneiss domes. Model results are relatively insensitive to channel heterogeneities and to variations in the behavior of the mantle lithosphere beneath the model plateau.

Journal ArticleDOI
TL;DR: It is proposed that the processes by which a cell enters into, maintains viability in, and exits from quiescence are best viewed as an environmentally triggered cycle: the cell quiescent cycle.
Abstract: The cells of organisms as diverse as bacteria and humans can enter stable, nonproliferating quiescent states. Quiescent cells of eukaryotic and prokaryotic microorganisms can survive for long periods without nutrients. This alternative state of cells is still poorly understood, yet much benefit is to be gained by understanding it both scientifically and with reference to human health. Here, we review our knowledge of one “model” quiescent cell population, in cultures of yeast grown to stationary phase in rich media. We outline the importance of understanding quiescence, summarize the properties of quiescent yeast cells, and clarify some definitions of the state. We propose that the processes by which a cell enters into, maintains viability in, and exits from quiescence are best viewed as an environmentally triggered cycle: the cell quiescence cycle. We synthesize what is known about the mechanisms by which yeast cells enter into quiescence, including the possible roles of the protein kinase A, TOR, protein kinase C, and Snf1p pathways. We also discuss selected mechanisms by which quiescent cells maintain viability, including metabolism, protein modification, and redox homeostasis. Finally, we outline what is known about the process by which cells exit from quiescence when nutrients again become available.

Journal ArticleDOI
TL;DR: Consensus approach is only an interim guide to a complex disorder such as HAE and should be replaced as soon as possible with large phase III and IV clinical trials, meta analyses, and using data base registry validation of approaches.
Abstract: C1 inhibitor deficiency (hereditary angioedema [HAE]) is a rare disorder for which there is a lack of consensus concerning diagnosis, therapy, and management, particularly in Canada. European initiatives have driven the approach to managing HAE with 3 C1-INH Deficiency Workshops held every 2 years in Hungary starting in 1999, with the third Workshop having recently been held in May 2003. The European Contact Board has established a European HAE Registry that will hopefully advance our knowledge of this disorder. The Canadian Hereditary Angioedema Society/Societe d'Angioedeme Hereditaire du Canada organized a Canadian International Consensus Conference held in Toronto, Ontario, Canada, on October 24 to 26, 2003, to foster consensus between major European and North American HAE treatment centers. Papers were presented by investigators from Europe and North America, and this consensus algorithm approach was discussed. There is a paucity of double-blind placebo-controlled trials in the treatment of HAE, making levels of evidence to support the algorithm less than optimal. Enclosed is the consensus algorithm approach recommended for the diagnosis, therapy, and management of HAE and agreed to by the authors of this article. This document is only a consensus algorithm approach and requires validation. As such, participants agreed to make this a living 2003 algorithm (ie, a work in progress) and agreed to review its content at future international HAE meetings. The consensus, however, has strength in that it was arrived at by the meeting of patient-care providers along with patient group representatives and individual patients reviewing information available to date and reaching agreement on how to approach the diagnosis, therapy, and management of HAE circa 2003. Hopefully evidence to support approaches to the management of HAE will approach the level of meta-analysis of randomized controlled trials in the near future.

Journal ArticleDOI
TL;DR: A frailty index that is clinically sensible and practical for geriatricians by basing it on a routinely used comprehensive geriatric assessment instrument is constructed and validated.
Abstract: Objectives: To construct and validate a frailty index (FI) that is clinically sensible and practical for geriatricians by basing it on a routinely used comprehensive geriatric assessment (CGA) instrument. Design: Secondary analysis of a 3-month randomized, controlled trial of a specialized mobile geriatric assessment team. Setting: Rural Nova Scotia. Participants were seen in their homes. Participants: Frail older adults, of whom 92 were in the intervention group and 77 in the control group. Measurements: A standard CGA form that accounts for impairment, disability, and comorbidity burden was scored and summed as a frailty index (FI-CGA). The FI-GCA was stratified to describe three levels of frailty. Patients were followed for up to 12 months to determine how well the index predicted adverse outcomes (institutionalization or mortality, whichever came first). Results: The three levels of frailty were mild (FI-CGA 0–7), moderate (FI-CGA 7–13), and severe (FI-CGA>13). Demographic and social traits were similar across groups, but greater frailty was associated with worse function (r=0.55) and mental status (r=0.33). Those with moderate and severe frailty had a greater risk of adverse outcomes than those with mild frailty (unadjusted hazard ratio=1.9 and 5.5, respectively). There was no difference between frailty groups in mean 3-month goal-attainment scaling scores. Intrarater reliability was 0.95. Conclusion: The FI-CGA is a valid, reliable, and sensible clinical measure of frailty that permits risk stratification of future adverse outcomes.

Journal ArticleDOI
TL;DR: Fitness and frailty form a continuum and predict survival, even in old age, and are potentially useful markers of the risk for adverse health outcomes, and add value to traditional medical assessments that focus on diagnoses.
Abstract: Background. Frailty and fitness are important attributes of older persons, but population samples of their prevalence, attributes, and outcomes are limited. Methods. The authors report data from the community-dwelling sample (n ¼ 9008) of the Canadian Study of Health and Aging, a representative, 5-year prospective cohort study. Fitness and frailty were determined by self-reported exercise and function level and testing of cognition. Results. Among the community-dwelling elderly population, 171 per 1000 were very fit and 12 per 1000 were very frail. Frailty increased with age, so that by age 85 years and older, 44 per 1000 were very frail. The risk for adverse health outcomes increased markedly with frailty: Compared with older adults who exercise, those who were moderately or severely frail had a relative risk for institutionalization of 8.6 (95% confidence interval, 4.9 to 15.2) and for death of 7.3 (95% confidence interval, 4.7 to 11.4). These risks persist after adjustments for age, sex, comorbid conditions, and poor self-rated health. At all ages, men reported higher levels of exercise and less frailty compared with women. Decreased fitness and increased frailty were also associated with poor self-ratings of health (42% in the most frail vs 7% in the most fit), more comorbid illnesses (6 vs 3), and more social isolation (34% vs 29%). Conclusions. Fitness and frailty form a continuum and predict survival. Exercise influences survival, even in old age. Relative fitness and frailty can be determined quickly in a clinical setting, are potentially useful markers of the risk for adverse health outcomes, and add value to traditional medical assessments that focus on diagnoses.

Journal ArticleDOI
TL;DR: The LS-PGA, which is standardized, does not require experience, and provides discrete word-based scores with intrinsic meaning, is a reliable measure of therapeutic effect in psoriasis, and would allow comparisons across different clinical trials.
Abstract: Background Reliable assessment of severity in psoriasis is essential to document treatment responses in clinical research. The reliability of current clinical outcome measures is uncertain. Objective To quantify the relative variation in commonly used outcome measures (the Psoriasis Area and Severity Index [PASI] and one version of the Psoriasis Global Assessment [PGA]), and a newer measure, the Lattice System Physician's Global Assessment (LS-PGA). Methods Physicians who were experienced (53%; 9/17) or inexperienced (47%; 8/17) in using PASI and PGA evaluated 35 patients with psoriasis in random order twice with each rating system. We assessed the variation in scoring psoriasis severity within (intrarater) and among (interrater) physicians. Results PASI, PGA, and LS-PGA were highly correlated (r>0.8 for all comparisons) and had high overall reliability (Cronbach's α>0.9 for each). PGA and LS-PGA had lower intrarater variation than PASI. LS-PGA had a 55% higher concordance coefficient between the two evaluations than did PGA. Interrater variation was lower for PGA and LS-PGA than for PASI both before and after correction for measurement error. Experience was beneficial in reducing variation in PASI scores but was not required with PGA or LS-PGA. Conclusion The LS-PGA, which is standardized, does not require experience, and provides discrete word-based scores with intrinsic meaning, is a reliable measure of therapeutic effect in psoriasis, and would allow comparisons across different clinical trials.

Journal ArticleDOI
TL;DR: Risperidone was well tolerated and efficacious in treating behavioral symptoms associated with PDD in children and seemed manageable with dose/dose-schedule modification.
Abstract: Objective. To investigate the efficacy and safety of risperidone for the treatment of disruptive behavioral symptoms in children with autism and other pervasive developmental disorders (PDD). Methods. In this 8-week, randomized, double-blind, placebo-controlled trial, risperidone/placebo solution (0.01–0.06 mg/kg/day) was administered to 79 children who were aged 5 to 12 years and had PDD. Behavioral symptoms were assessed using the Aberrant Behavior Checklist (ABC), Nisonger Child Behavior Rating Form, and Clinical Global Impression-Change. Safety assessments included vital signs, electrocardiogram, extrapyramidal symptoms, adverse events, and laboratory tests. Results. Subjects who were taking risperidone (mean dosage: 0.04 mg/kg/day; 1.17 mg/day) experienced a significantly greater mean decrease on the irritability subscale of the ABC (primary endpoint) compared with those who were taking placebo. By study endpoint, risperidone-treated subjects exhibited a 64% improvement over baseline in the irritability score almost double that of placebo-treated subjects (31%). Risperidone-treated subjects also exhibited significantly greater decreases on the other 4 subscales of the ABC; on the conduct problem, insecure/anxious, hyperactive, and overly sensitive subscales of the Nisonger Child Behavior Rating Form (parent version); and on the Visual Analog Scale of the most troublesome symptom. More risperidone-treated subjects (87%) showed global improvement in their condition compared with the placebo group (40%). Somnolence, the most frequently reported adverse event, was noted in 72.5% versus 7.7% of subjects (risperidone vs placebo) and seemed manageable with dose/dose-schedule modification. Risperidone-treated subjects experienced statistically significantly greater increases in weight (2.7 vs 1.0 kg), pulse rate, and systolic blood pressure. Extrapyramidal symptoms scores were comparable between groups. Conclusions. Risperidone was well tolerated and efficacious in treating behavioral symptoms associated with PDD in children.

Journal ArticleDOI
01 Apr 2004-Nature
TL;DR: The depletion of silicic acid and the inefficient transfer of iron-increased POC below the permanent thermocline have major implications both for the biogeochemical interpretation of times of greater iron supply in the geological past, and also for proposed geo-engineering schemes to increase oceanic carbon sequestration.
Abstract: Iron supply has a key role in stimulating phytoplankton blooms in high-nitrate low-chlorophyll oceanic waters. However, the fate of the carbon fixed by these blooms, and how efficiently it is exported into the ocean's interior, remains largely unknown. Here we report on the decline and fate of an iron-stimulated diatom bloom in the Gulf of Alaska. The bloom terminated on day 18, following the depletion of iron and then silicic acid, after which mixed-layer particulate organic carbon (POC) concentrations declined over six days. Increased particulate silica export via sinking diatoms was recorded in sediment traps at depths between 50 and 125 m from day 21, yet increased POC export was not evident until day 24. Only a small proportion of the mixed-layer POC was intercepted by the traps, with more than half of the mixed-layer POC deficit attributable to bacterial remineralization and mesozooplankton grazing. The depletion of silicic acid and the inefficient transfer of iron-increased POC below the permanent thermocline have major implications both for the biogeochemical interpretation of times of greater iron supply in the geological past, and also for proposed geo-engineering schemes to increase oceanic carbon sequestration.

Journal ArticleDOI
TL;DR: An ongoing, international dialogue about the relationship between occupation, justice, and client-centred practice, prompted by the question: How do occupational therapists work for justice is described, encouraging occupational therapists to develop their own dialogue about occupational injustices.
Abstract: Background. This paper describes an ongoing, international dialogue about the relationship between occupation, justice, and client-centred practice, prompted by the question: How do occupational therapists work for justice? Methods. The authors critically reflect on their own dialogue and culturally situated interests, dialogues with workshop participants, and a literature review. Results. Four cases of occupational injustice are proposed: occupational alienation, occupational deprivation, occupational marginalization, and occupational imbalance. The naming of these occupational injustices suggests four occupational rights: to experience meaning and enrichment in one's occupations; to participate in a range of occupations for health and social inclusion; to make choices and share decision-making power in daily life; and to receive equal privileges for diverse participation in occupations. Practice Implications. Since silence implies compliance with the status quo, the authors encourage occupational therap...

Journal ArticleDOI
TL;DR: Integration of these models used to describe the caregiving process from two diverse fields, pediatrics and geriatrics, into one comprehensive model suitable for this population of children with disabilities and their caregivers is proposed.
Abstract: Parental care for a child with a developmental disability is an enormous responsibility, one that can far exceed that of typical parental care. While most parents adapt well to the situation of caring for a child with a disability, some do not. To understand parents' adaptations to their children's disabilities, the complex nature of stress processes must be accounted for and the constructs and factors that play a role in the caregiving must be considered. Evidence suggests that there is considerable variation in how caregivers adapt to their caregiving demands. Many studies have sought to qualify the association between caregiving and health outcomes of the caregivers. Contextual factors such as SES, child factors such as child behaviour problems and severity of disability, intra-psychic factors such as mastery and self-esteem, coping strategies and social supports have all been associated with psychological and/or physical outcome or parents or primary caregivers. In reviewing these issues, the literature appears to be limited by the use of traditional analytic approaches which examine the relationship between a factor and an outcome. It is clear, however, that changes to single factors, as represented in these studies, occur very rarely even in the experimental context. The literature has also been limited by lack of reliance on specific theoretical frameworks. This conceptual paper documents the state of current knowledge and explores the current theoretical frameworks that have been used to describe the caregiving process from two diverse fields, pediatrics and geriatrics. Integration of these models into one comprehensive model suitable for this population of children with disabilities and their caregivers is proposed. This model may guide future research in this area.

Journal ArticleDOI
TL;DR: In this article, the authors compare initial (1950s) and recent (late 1990s) standardized catch rates of pelagic sharks in the Gulf of Mexico, the area where methods of exploitation between these two periods were most comparable.
Abstract: Historical abundances of many large marine vertebrates were tremendously greater than today. However, while pelagic sharks are known to have declined rapidly in the northwest Atlantic in recent years, there, as elsewhere, little is known about the former natural abundances of these species. Here, we compare initial (1950s) and recent (late1990s) standardized catch rates of pelagic sharks in the Gulf of Mexico, the area where methods of exploitation between these two periods were most comparable. We estimate that oceanic whitetip and silky sharks, formerly the most commonly caught shark species, have declined by over 99 and 90%, respectively. That the former prevalence of oceanic whitetip sharks in this ecosystem is unrecognized today is clear evidence of shifting baselines. Our analysis provides the missing baseline for pelagic sharks in the Gulf of Mexico that is needed for the rational management and restoration of these species.

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TL;DR: The findings from this literature both support the original hypothesis and suggest important modifications of the perception-action hypothesis and the ongoing challenge for neurobiologists is to map these behavioural findings onto their corresponding neural substrates.

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TL;DR: The data interpreted to mean that MS susceptibility is genetically influenced, and a single dominant or even a single recessive gene is unlikely to account for this effect is unlikely, suggests that at least two or more genes are operative.
Abstract: This study is a 7.5-year follow-up of a population-based series of twins with multiple sclerosis (MS) whose mean age now exceeds 50 years. The twin pairs were identified through the Canadian nationwide system of MS clinics and were drawn from a population of 5,463 patients. After 7.5 years, the monozygotic concordance rate increased from 25.9 to 30.8% and the dizygotic-like sex concordance rate from 2.4 to 4.7%. These results are very similar to those of other population-based studies and to our own modified replication twin data reported here. We interpret the data to mean that MS susceptibility is genetically influenced, and a single dominant or even a single recessive gene is unlikely to account for this effect. The difference in concordance rates suggests that at least two or more genes are operative. These data also have important implications for the nature of the environmental effect(s) in MS susceptibility. Most monozygotic twins are discordant even after a correction for age and magnetic resonance imaging findings. This unambiguously demonstrates the powerful effect of nonheritable factors.

Journal ArticleDOI
TL;DR: In this article, the role of coating LiCoO 2 with oxides in improving the capacity retention of LiO 2 cycled to 4.5 V has been discussed, and it is shown that the mechanism for the improvement in capacity retention proposed by Cho et al. is incorrect.

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TL;DR: Magnesium given within 12 h of acute stroke does not reduce the chances of death or disability significantly, although it may be of benefit in lacunar strokes.

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TL;DR: Parrot feather showed greater tolerance to toxicity followed by water mint and creeping primrose, and the growth of creeps primrose was significantly affected by heavy metal toxicity.

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TL;DR: In this article, a thermal-mechanical model (HT1) that includes midcrustal channel flow is compatible with many features of the Himalayan-Tibetan system.
Abstract: [1] Results from a thermal-mechanical model (HT1) that includes midcrustal channel flow are compatible with many features of the Himalayan-Tibetan system. Radioactive self-heating and rheological weakening of thickened model orogenic crust lead to the formation of a hot, low-viscosity midcrustal channel and a broad plateau. Channel material, corresponding to the Greater Himalayan Sequence (GHS), flows outward from beneath the plateau in response to topographically induced differential pressure. At the plateau flank it is exhumed by focused surface denudation and juxtaposed with cooler, newly accreted material corresponding to the Lesser Himalayan Sequence (LHS). The model channel is bounded by coeval thrust and normal sense ductile shear zones, interpreted to represent the Main Central Thrust (MCT) zone and South Tibetan Detachment system, respectively. Inverted metamorphism associated with the model MCT zone results from distributed ductile shear along the MCT and extrusion of the hot channel. A variety of model P-T-t path styles, resembling those observed in the GHS and LHS, are produced for points traveling through contrasting tectonic regimes that coexist in different parts of the model. Predicted times of peak metamorphism, cooling, and erosion of metamorphic facies are generally compatible with observations, although model GHS cooling ages are too young. The times of M1 and M2 metamorphic “events” observed in the GHS correspond to model times of maximum burial and maximum heating, respectively. The results highlight the need to integrate tectonics and metamorphism in continental collision models and demonstrate the importance of lateral transport of both heat and material in large hot orogens.

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TL;DR: The major problems in interpreting the results of immune assays are: (1) correlations between assays of immunity and disease resistance are typically pathogen specific, (2) correlation between assay results are sometimes weak or nonexistent, (3) research suggests that some immune components have a threshold value such that changes above that threshold value may have no biological significance, and (4) the immune system can change its response characteristics in order to optimize its defence against different kinds of intruders.