230 research outputs found

    Future climate stimulates population out-breaks by relaxing constraints on reproduction

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    When conditions are stressful, reproduction and population growth are reduced, but when favourable, reproduction and population size can boom. Theory suggests climate change is an increasingly stressful environment, predicting extinctions or decreased abundances. However, if favourable conditions align, such as an increase in resources or release from competition and predation, future climate can fuel population growth. Tests of such population growth models and the mechanisms by which they are enabled are rare. We tested whether intergenerational increases in population size might be facilitated by adjustments in reproductive success to favourable environmental conditions in a large-scale mesocosm experiment. Herbivorous amphipod populations responded to future climate by increasing 20 fold, suggesting that future climate might relax environmental constraints on fecundity. We then assessed whether future climate reduces variation in mating success, boosting population fecundity and size. The proportion of gravid females doubled, and variance in phenotypic variation of male secondary sexual characters (i.e. gnathopods) was significantly reduced. While future climate can enhance individual growth and survival, it may also reduce constraints on mechanisms of reproduction such that enhanced intra-generational productivity and reproductive success transfers to subsequent generations. Where both intra and intergenerational production is enhanced, population sizes might boom.Katherine A. Heldt, Sean D. Connell, Kathryn Anderson, Bayden D. Russell, Pablo Mungui

    Spectrum-Guided Adversarial Disparity Learning

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    It has been a significant challenge to portray intraclass disparity precisely in the area of activity recognition, as it requires a robust representation of the correlation between subject-specific variation for each activity class. In this work, we propose a novel end-to-end knowledge directed adversarial learning framework, which portrays the class-conditioned intraclass disparity using two competitive encoding distributions and learns the purified latent codes by denoising learned disparity. Furthermore, the domain knowledge is incorporated in an unsupervised manner to guide the optimization and further boosts the performance. The experiments on four HAR benchmark datasets demonstrate the robustness and generalization of our proposed methods over a set of state-of-the-art. We further prove the effectiveness of automatic domain knowledge incorporation in performance enhancement

    Non-existence of stationary two-black-hole configurations: The degenerate case

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    In a preceding paper we examined the question whether the spin-spin repulsion and the gravitational attraction of two aligned sub-extremal black holes can balance each other. Based on the solution of a boundary value problem for two separate (Killing-) horizons and a novel black hole criterion we were able to prove the non-existence of the equilibrium configuration in question. In this paper we extend the non-existence proof to extremal black holes.Comment: 18 pages, 2 figure

    Is facilitation a true species interaction?

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    Current ecological literature considers facilitation to be a positive interaction alongside symbiosis or mutualism. But unlike these interactions, the fitness of one of the species involved in facilitation remains unaffected which precludes coevolution. Therefore, we believe that facilitation is not a true species interaction and should be kept within the framework of succession.Pablo Munguia, Alfredo F. Ojanguren, Andrew N. Evans, Laura Ryckman, Brad Gemmell, Colt Cook, Geoff Hensge

    Seroepidemiology of SARS-CoV-2 infections in an urban population-based cohort in León, Nicaragua

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    In a Nicaraguan population-based cohort, SARS-CoV-2 seroprevalence reached 28% in the first 6 months of the country's epidemic and reached 35% 6 months later. Immune waning was uncommon. Individuals with a seropositive household member were over three times as likely to be seropositive themselves, suggesting the importance of household transmission

    Urinary bisphenol A concentrations in girls from rural and urban Egypt: a pilot study

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    Abstract Background Exposure to endocrine active compounds, including bisphenol A (BPA), remains poorly characterized in developing countries despite the fact that behavioral practices related to westernization have the potential to influence exposure. BPA is a high production volume chemical that has been associated with metabolic dysfunction as well as behavioral and developmental effects in people, including children. In this pilot study, we evaluate BPA exposure and assess likely pathways of exposure among girls from urban and rural Egypt. Methods We measured urinary concentrations of total (free plus conjugated) species of BPA in spot samples in urban (N = 30) and rural (N = 30) Egyptian girls, and compared these concentrations to preexisting data from age-matched American girls (N = 47) from the U.S. National Health and Nutrition Examination Survey (NHANES). We also collected anthropometric and questionnaire data regarding food storage behaviors to assess potential routes of exposure. Results Urban and rural Egyptian girls exhibited similar concentrations of urinary total BPA, with median unadjusted values of 1.00 and 0.60 ng/mL, respectively. Concentrations of urinary BPA in this group of Egyptian girls (median unadjusted: 0.70 ng/mL) were significantly lower compared to age-matched American girls (median unadjusted: 2.60 ng/mL) according to NHANES 2009-2010 data. Reported storage of food in plastic containers was a significant predictor of increasing concentrations of urinary BPA. Conclusions Despite the relatively low urinary BPA concentrations within this Egyptian cohort, the significant association between food storage behaviors and increasing urinary BPA concentration highlights the need to understand food and consumer product patterns that may be closing the gap between urban and rural lifestyles.http://deepblue.lib.umich.edu/bitstream/2027.42/112495/1/12940_2011_Article_523.pd

    The placebo effect and its determinants in fibromyalgia: meta-analysis of randomized controlled trials

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    The aims of this study were to determine whether placebo treatment in randomised controlled trials (RCTs) is effective for fibromyalgia and to identify possible determinants of the magnitude of any such placebo effect. A systematic literature search was undertaken for RCTs in people with fibromyalgia that included a placebo and/or a no-treatment (observation only or waiting list) control group. Placebo effect size (ES) for pain and other outcomes was measured as the improvement of each outcome from baseline divided by the standard deviation of the change from baseline. This effect was compared with changes in the no-treatment control groups. Meta-analysis was undertaken to combine data from different studies. Subgroup analysis was conducted to identify possible determinants of the placebo ES. A total of 3912 studies were identified from the literature search. After scrutiny, 229 trials met the inclusion criteria. Participants who received placebo in the RCTs experienced significantly better improvements in pain, fatigue, sleep quality, physical function, and other main outcomes than those receiving no treatment. The ES of placebo for pain relief was clinically moderate (0.53, 95%CI 0.48 to 0.57). The ES increased with increasing strength of the active treatment, increasing participant age and higher baseline pain severity, but decreased in RCTS with more women and with longer duration of fibromyalgia. In addition, placebo treatment in RCTs is effective in fibromyalgia. A number of factors (expected strength of treatment, age, gender, disease duration) appear to influence the magnitude of the placebo effect in this condition

    Exercise and global well-being in community-dwelling adults with fibromyalgia: a systematic review with meta-analysis

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    <p>Abstract</p> <p>Background</p> <p>Exercise has been recommended for improving global-well being in adults with fibromyalgia. However, no meta-analysis has determined the effects of exercise on global well-being using a single instrument and when analyzed separately according to intention-to-treat and per-protocol analyses. The purpose of this study was to fill that gap.</p> <p>Methods</p> <p>Studies were derived from six electronic sources, cross-referencing from retrieved studies and expert review. Dual selection of randomized controlled exercise training studies published between January 1, 1980 and January 1, 2008 and in which global well-being was assessed using the Fibromyalgia Impact Questionnaire (FIQ) were included. Dual abstraction of data for study, subject and exercise program characteristics as well as assessment of changes in global well-being using the total score from the FIQ was conducted. Risk of bias was assessed using the Cochrane bias assessment tool. Random-effects models and Hedge's standardized effect size (<it>g</it>) were used to pool results according to per-protocol and intention-to-treat analyses.</p> <p>Results</p> <p>Of 1,025 studies screened, 7 representing 5 per-protocol and 5 intention-to-treat outcomes in 473 (280 exercise, 193 control) primarily female (99%) participants 18-73 years of age were included. Small, statistically significant improvements in global well-being were observed for per-protocol (<it>g </it>and 95% confidence interval, -0.39, -0.69 to -0.08) and intention-to-treat (-0.34, -0.53 to -0.14) analyses. No statistically significant within-group heterogeneity was found (per-protocol, Q<sub>w </sub>= 6.04, <it>p </it>= 0.20, <it>I</it><sup>2 </sup>= 33.8%; intention-to-treat, Q<sub>w </sub>= 3.19, <it>p </it>= 0.53, <it>I</it><sup>2 </sup>= 0%) and no between-group differences for per-protocol and intention-to-treat outcomes were observed (Q<sub>b </sub>= 0.07, <it>p </it>= 0.80). Changes were equivalent to improvements of 8.2% for per-protocol analyses and 7.3% for intention-to-treat analyses.</p> <p>Conclusions</p> <p>The results of this study suggest that exercise improves global well-being in community-dwelling women with fibromyalgia. However, additional research on this topic is needed, including research in men as well as optimal exercise programs for improving global well-being in adults.</p

    Keeping vigil over the profession: a grounded theory of the context of nurse anaesthesia practice

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    <p>Abstract</p> <p>Background</p> <p>Nurse anaesthetists in the US have faced continued, repeated challenges to their profession. Regardless, they have met these challenges and have established themselves as major anaesthesia care providers. In this paper we address the research question: How do certified registered nurse anaesthetists (CRNAs) manage the socio-political context in which they provide care for their patients?</p> <p>Methods</p> <p>Grounded theory was used to explore how nurse anaesthetists protect and promote their profession. Purposive, snowball, and theoretical sampling was used and data were collected through participant observation and interviews conducted at a conference of the professional association, an educational program, by telephone, email exchanges, and time spent in operating rooms and an outpatient surgical clinic. Analysis included coding at increasingly abstract levels and constant comparison.</p> <p>Results</p> <p>The basic social process identified was Keeping Vigil Over the Profession, which explains how nurse anaesthetists protect and promote their profession. It is comprised of three contextual categories: Establishing Public Credibility through regulatory and educational standards, Political Vigilance and taking action in governmental and policy arenas, and Tending the Flock through a continuous information loop between local and administrative/political levels.</p> <p>Conclusions</p> <p>From our study of the context of nurse anaesthesia practice, it is clear that CRNAs are dedicated to protecting their ability to provide high quality patient care by maintaining constant vigilance over their profession.</p
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