Institution
University of Alberta
Education•Edmonton, Alberta, Canada•
About: University of Alberta is a education organization based out in Edmonton, Alberta, Canada. It is known for research contribution in the topics: Population & Health care. The organization has 65403 authors who have published 154847 publications receiving 5358338 citations. The organization is also known as: Ualberta & UAlberta.
Papers published on a yearly basis
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TL;DR: In this article, the authors demonstrate the use of piecewise regression as a statistical technique to model ecological thresholds and demonstrate the need for a careful study of the likelihood surface when fitting and interpreting the results from piecewise-regression models.
Abstract: We demonstrate the use of piecewise regression as a statistical technique to model ecological thresholds. Recommended procedures for analysis are illustrated with a case study examining the width of edge effects in two understory plant communities. Piece-wise regression models are “broken-stick” models, where two or more lines are joined at unknown points, called “breakpoints.” Breakpoints can be used as estimates of thresholds and are used here to determine the width of edge effects. We compare a sharp-transition model with three models incorporating smooth transitions: the hyperbolic-tangent, bent-hyperbola, and bent-cable models. We also calculate three types of confidence intervals for the breakpoint estimate: an interval based on the computed standard error of the estimate from the fitting procedure, an empirical bootstrap confidence interval, and a confidence interval derived from an inverted F test. We recommend use of the inverted F test confidence interval when sample sizes are large, and cautious use of bootstrapped confidence intervals when sample sizes are smaller. Our analysis demonstrates the need for a careful study of the likelihood surface when fitting and interpreting the results from piecewise-regression models.
843 citations
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Pennington Biomedical Research Center1, University of Sydney2, University of Alberta3, University of Southern Maine4, Ghent University5, University of Newcastle6, University of Oklahoma Health Sciences Center7, Tokyo Gakugei University8, East Carolina University9, Southern Illinois University School of Medicine10, University of Puerto Rico11, University of Strathclyde12, Menzies Research Institute13, University of Georgia14, Queen's University Belfast15, University of South Carolina16
TL;DR: The evidence suggests that 30 minutes of daily MVPA accumulated in addition to habitual daily activities in healthy older adults is equivalent to taking approximately 7,000-10,000 steps/day, which approximates 8,000 Steps on days that include a target of achieving 20 minutes of moderate-to-vigorous physical activity (MVPA).
Abstract: Older adults and special populations (living with disability and/or chronic illness that may limit mobility and/or physical endurance) can benefit from practicing a more physically active lifestyle, typically by increasing ambulatory activity. Step counting devices (accelerometers and pedometers) offer an opportunity to monitor daily ambulatory activity; however, an appropriate translation of public health guidelines in terms of steps/day is unknown. Therefore this review was conducted to translate public health recommendations in terms of steps/day. Normative data indicates that 1) healthy older adults average 2,000-9,000 steps/day, and 2) special populations average 1,200-8,800 steps/day. Pedometer-based interventions in older adults and special populations elicit a weighted increase of approximately 775 steps/day (or an effect size of 0.26) and 2,215 steps/day (or an effect size of 0.67), respectively. There is no evidence to inform a moderate intensity cadence (i.e., steps/minute) in older adults at this time. However, using the adult cadence of 100 steps/minute to demark the lower end of an absolutely-defined moderate intensity (i.e., 3 METs), and multiplying this by 30 minutes produces a reasonable heuristic (i.e., guiding) value of 3,000 steps. However, this cadence may be unattainable in some frail/diseased populations. Regardless, to truly translate public health guidelines, these steps should be taken over and above activities performed in the course of daily living, be of at least moderate intensity accumulated in minimally 10 minute bouts, and add up to at least 150 minutes over the week. Considering a daily background of 5,000 steps/day (which may actually be too high for some older adults and/or special populations), a computed translation approximates 8,000 steps on days that include a target of achieving 30 minutes of moderate-to-vigorous physical activity (MVPA), and approximately 7,100 steps/day if averaged over a week. Measured directly and including these background activities, the evidence suggests that 30 minutes of daily MVPA accumulated in addition to habitual daily activities in healthy older adults is equivalent to taking approximately 7,000-10,000 steps/day. Those living with disability and/or chronic illness (that limits mobility and or/physical endurance) display lower levels of background daily activity, and this will affect whole-day estimates of recommended physical activity.
842 citations
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TL;DR: In this article, the authors show that sulfate reduction in diagenetic environments occurs in two mutually exclusive thermal regimes, i.e., low-temperature and hightemperature, respectively.
840 citations
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TL;DR: In a group of patients with chronically active Crohn's disease, methotrexate was more effective than placebo in improving symptoms and reducing requirements for prednisone.
Abstract: Background Although corticosteroids are highly effective in improving symptoms of Crohn's disease, they may have substantial toxicity. In some patients, attempts to discontinue corticosteroids are ...
839 citations
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TL;DR: In this article, the authors document the development of the body of work known as women's entrepreneurship research and assess the contributions of this work, specifically vis-a-vis the broader entrepreneurship literature.
Abstract: This paper has three overarching objectives. The first is to document the development of the body of work known as women's entrepreneurship research. The second is to assess the contributions of this work, specifically vis-a-vis the broader entrepreneurship literature. The third is to discuss how this broader literature poses challenges (both difficulties as well as opportunities) for scholarship on female entrepreneurs. We approach these objectives from the standpoint of informed pluralism, seeking to explore whether and how women's entrepreneurship research offers extensions to—and can be extended by—general research on entrepreneurs and their ventures.
839 citations
Authors
Showing all 66027 results
Name | H-index | Papers | Citations |
---|---|---|---|
Salim Yusuf | 231 | 1439 | 252912 |
Yi Chen | 217 | 4342 | 293080 |
Robert M. Califf | 196 | 1561 | 167961 |
Douglas R. Green | 182 | 661 | 145944 |
Russel J. Reiter | 169 | 1646 | 121010 |
Jiawei Han | 168 | 1233 | 143427 |
Jaakko Kaprio | 163 | 1532 | 126320 |
Tobin J. Marks | 159 | 1621 | 111604 |
Josef M. Penninger | 154 | 700 | 107295 |
Subir Sarkar | 149 | 1542 | 144614 |
Gerald M. Edelman | 147 | 545 | 69091 |
Rinaldo Bellomo | 147 | 1714 | 120052 |
P. Sinervo | 138 | 1516 | 99215 |
David A. Jackson | 136 | 1095 | 68352 |
Andreas Warburton | 135 | 1578 | 97496 |