McGill University

About: McGill University is a education organization based out in Montreal, Quebec, Canada. It is known for research contribution in the topics: Population & Context (language use). The organization has 72688 authors who have published 162565 publications receiving 6966523 citations. The organization is also known as: Royal institution of advanced learning & University of McGill College.

On the Foundations of Relaxation Labeling Processes

Abstract: A large class of problems can be formulated in terms of the assignment of labels to objects. Frequently, processes are needed which reduce ambiguity and noise, and select the best label among several possible choices. Relaxation labeling processes are just such a class of algorithms. They are based on the parallel use of local constraints between labels. This paper develops a theory to characterize the goal of relaxation labeling. The theory is founded on a definition of con-sistency in labelings, extending the notion of constraint satisfaction. In certain restricted circumstances, an explicit functional exists that can be maximized to guide the search for consistent labelings. This functional is used to derive a new relaxation labeling operator. When the restrictions are not satisfied, the theory relies on variational cal-culus. It is shown that the problem of finding consistent labelings is equivalent to solving a variational inequality. A procedure nearly identical to the relaxation operator derived under restricted circum-stances serves in the more general setting. Further, a local convergence result is established for this operator. The standard relaxation labeling formulas are shown to approximate our new operator, which leads us to conjecture that successful applications of the standard methods are explainable by the theory developed here. Observations about con-vergence and generalizations to higher order compatibility relations are described.

Averting biodiversity collapse in tropical forest protected areas

Abstract: The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon(1-3). With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses(4-9). As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad array of biodiversity groups have been unavailable for a sufficiently large and representative sample of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the world's major tropical regions. Our analysis reveals great variation in reserve 'health': about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of biodiversity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious biodiversity declines.

Usefulness of the Berg Balance Scale in Stroke Rehabilitation: A Systematic Review

Abstract: Background. In a recent study of 655 physical therapists working with a stroke population, the Berg Balance Scale (BBS) was identified as the most commonly used assessment tool across the continuum of stroke rehabilitation. Given the widespread popularity of the BBS, it is important to critically appraise the BBS for its use with a stroke population. Objective. The purposes of this study were to conduct a systematic review of the psychometric properties of the BBS specific to stroke and to identify strengths and weaknesses in its usefulness for stroke rehabilitation. Results. Twenty-one studies examining the psychometric properties of the BBS with a stroke population were retrieved. Internal consistency was excellent (Cronbach alpha.92‐.98) as was interrater reliability (intraclass correlation coefficients [ICCs].95‐.98), intrarater reliability (ICC.97), and test-retest reliability (ICC.98). Sixteen studies focused on validity and generally found excellent correlations with the Barthel Index, the Postural Assessment Scale for Stroke Patients, Functional Reach Test, the balance subscale of Fugl-Meyer Assessment, the Functional Independence Measure, the Rivermead Mobility Index (except for weight shift and step-up items), and gait speed. Berg Balance Scale scores predicted length of stay, discharge destination, motor ability at 180 days poststroke, and disability level at 90 days, but these scores were not predictive of falls. Eight studies focused on responsiveness; all reported moderate to excellent sensitivity. Three studies found floor or ceiling effects. Discussion and Conclusion. The BBS is a psychometrically sound measure of balance impairment for use in poststroke assessment. Given the floor and ceiling effects, clinicians may want to use the BBS in conjunction with other balance measures.

IL-17 is increased in asthmatic airways and induces human bronchial fibroblasts to produce cytokines.

Abstract: Background: IL-17 is a cytokine that has been reported to be produced by T lymphocytes. In vitro, IL-17 activates fibro-blasts and macrophages for the secretion of GM-CSF, TNF-α, IL-1β, and IL-6. A number of these cytokines are involved in the airway remodeling that is observed within the lungs of asthmatic individuals. Objective: In this study, we investigated the expression of IL-17 in sputum and bronchoalveolar lavage specimens obtained from asthmatic subjects and from nonasthmatic control subjects. Methods: IL-17 was detected through use of immunocytochemistry, in situ hybridization, and Western blot. Bronchial fibroblasts were stimulated with IL-17, and cytokine production and chemokine production were detected through use of ELISA and RT-PCR. Results: Using immunocytochemistry, we demonstrated that the numbers of cells positive for IL-17 are significantly increased in sputum and bronchoalveolar lavage fluids of subjects with asthma in comparison with control subjects ( P P P Conclusion: Our results, which demonstrate for the first time that eosinophils are a potential source of IL-17 within asthmatic airways, suggest that IL-17 might have the potential to amplify inflammatory responses through the release of proinflammatory mediators such as α-chemokines. (J Allergy Clin Immunol 2001;108:430-8.)