786 resultados para covariates


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Carcass removal by scavengers has been identified as one of the largest biases in estimating bird mortality from anthropogenic sources. Only two studies have examined carcass removal by scavengers in an urban environment, and previous estimates of bird-window collision mortality at houses have relied on carcass removal rates from wind turbine studies. We placed a bird carcass and time-lapse camera at 44 houses in Edmonton, Alberta. In total, 166 7-day trials were conducted throughout 2015. Time-to-event (survival) analysis was used to identify covariates that affected removal. The carcass removal rate was determined for use in estimating the number of birds killed from bird-window collisions at houses in Alberta. In total, 67.5% of carcasses were removed. The date the carcass was placed, the year the house was built, and the level of development within 50 m of the house were the covariates that had the largest effect on carcass removal. In calculating our removal rate, the number of detected carcasses in the first 24 hours was adjusted by 1.47 to account for removal by scavengers. Previously collected citizen science data were used to create an estimate of 957,440 bird deaths each year in Alberta as a result of bird-window collisions with houses. This number is based on the most detailed bird-window collision study at houses to date and a carcass removal study conducted in the same area. Similar localized studies across Canada will need to be completed to reduce the biases that exist with the previous bird-window collision mortality estimate for houses in Canada.

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Cardiovascular disease is one of the leading causes of death around the world. Resting heart rate has been shown to be a strong and independent risk marker for adverse cardiovascular events and mortality, and yet its role as a predictor of risk is somewhat overlooked in clinical practice. With the aim of highlighting its prognostic value, the role of resting heart rate as a risk marker for death and other adverse outcomes was further examined in a number of different patient populations. A systematic review of studies that previously assessed the prognostic value of resting heart rate for mortality and other adverse cardiovascular outcomes was presented. New analyses of nine clinical trials were carried out. Both the original and extended Cox model that allows for analysis of time-dependent covariates were used to evaluate and compare the predictive value of baseline and time-updated heart rate measurements for adverse outcomes in the CAPRICORN, EUROPA, PROSPER, PERFORM, BEAUTIFUL and SHIFT populations. Pooled individual patient meta-analyses of the CAPRICORN, EPHESUS, OPTIMAAL and VALIANT trials, and the BEAUTIFUL and SHIFT trials, were also performed. The discrimination and calibration of the models applied were evaluated using Harrell’s C-statistic and likelihood ratio tests, respectively. Finally, following on from the systematic review, meta-analyses of the relation between baseline and time-updated heart rate, and the risk of death from any cause and from cardiovascular causes, were conducted. Both elevated baseline and time-updated resting heart rates were found to be associated with an increase in the risk of mortality and other adverse cardiovascular events in all of the populations analysed. In some cases, elevated time-updated heart rate was associated with risk of events where baseline heart rate was not. Time-updated heart rate also contributed additional information about the risk of certain events despite knowledge of baseline heart rate or previous heart rate measurements. The addition of resting heart rate to the models where resting heart rate was found to be associated with risk of outcome improved both discrimination and calibration, and in general, the models including time-updated heart rate along with baseline or the previous heart rate measurement had the highest and similar C-statistics, and thus the greatest discriminative ability. The meta-analyses demonstrated that a 5bpm higher baseline heart rate was associated with a 7.9% and an 8.0% increase in the risk of all-cause and cardiovascular death, respectively (both p less than 0.001). Additionally, a 5bpm higher time-updated heart rate (adjusted for baseline heart rate in eight of the ten studies included in the analyses) was associated with a 12.8% (p less than 0.001) and a 10.9% (p less than 0.001) increase in the risk of all-cause and cardiovascular death, respectively. These findings may motivate health care professionals to routinely assess resting heart rate in order to identify individuals at a higher risk of adverse events. The fact that the addition of time-updated resting heart rate improved the discrimination and calibration of models for certain outcomes, even if only modestly, strengthens the case that it be added to traditional risk models. The findings, however, are of particular importance, and have greater implications for the clinical management of patients with pre-existing disease. An elevated, or increasing heart rate over time could be used as a tool, potentially alongside other established risk scores, to help doctors identify patient deterioration or those at higher risk, who might benefit from more intensive monitoring or treatment re-evaluation. Further exploration of the role of continuous recording of resting heart rate, say, when patients are at home, would be informative. In addition, investigation into the cost-effectiveness and optimal frequency of resting heart rate measurement is required. One of the most vital areas for future research is the definition of an objective cut-off value for the definition of a high resting heart rate.

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Introducción: El tacrolimus es el medicamento de elección para evitar el rechazo al injerto hepático. Su dosis se ajusta a partir de los niveles séricos que se toman periódicamente para asegurar rango terapéutico. Además, niveles elevados se asocian con disfunción renal postrasplante. Sin embargo, no hay consenso frente a los niveles adecuados para pacientes con trasplante hepático. Objetivo: Determinar la relación entre los niveles de tacrolimus y la presencia de rechazo agudo al injerto hepático en pacientes con trasplante hepático realizado en la Fundación Cardioinfantil – Instituto de Cardiología (FCI-IC). Determinar la relación entre los niveles de tacrolimus y la TFG en pacientes con trasplante hepático realizado en la FCI-IC. Métodos: Estudio observacional tipo cohorte histórica en pacientes adultos con trasplante hepático realizado en la FCI-IC entre 2009-2014. Resultados: No se encontró una asociación estadísticamente significativa entre los niveles de tacrolimus y la presencia de rechazo agudo, en sus diferentes definiciones (OR=1,02, p=0,14 y OR=1,01, p=0,29) incluso al ajustar por otras covariables (OR=1,03, p=0,10 y OR=1,02, p=0,25). No fue posible corroborar el diagnóstico con biopsia porque no todos la tenían. Si bien la relación entre los niveles de tacrolimus y la TFG fue estadísticamente significativa (p≤0,001), tiene bajo impacto clínico, pues la TFG disminuyó menos de un punto por cada incremento en 1 ng/ml en los niveles de tacrolimus. Conclusiones: Se necesitan más estudios para establecer la relación entre la exposición a tacrolimus y estos desenlaces para definir si es seguro disminuir su dosis con el fin de reducir los eventos adversos.

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This study analyzes the impact of individual characteristics as well as occupation and industry on male wage inequality in nine European countries. Unlike previous studies, we consider regression models for five inequality measures and employ the recentered influence function regression method proposed by Firpo et al. (2009) to test directly the influence of covariates on inequality. We conclude that there is heterogeneity in the effects of covariates on inequality across countries and throughout wage distribution. Heterogeneity among countries is more evident in education and experience whereas occupation and industry characteristics as well as holding a supervisory position reveal more similar effects. Our results are compatible with the skill biased technological change, rapid rise in the integration of trade and financial markets as well as explanations related to the increase of the remunerative package of top executives.

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Failure to detect a species at sites where it is present (i.e. imperfect detection) is known to occur frequently, but this is often disregarded in monitoring programs and metapopulation studies. Here we modelled for the first time the probability of patch occupancy by a threatened small mammal, the southern water vole (Arvicola sapidus, while accounting for the probability of detection given occupancy. Based on replicated presence sign surveys conducted in autumn (November–December 2013) and winter (February–March 2014) in a farmland landscape, we used occupancy detection modelling to test the effects of vegetation, sampling effort, observer experience, and rainfall on detection probability. We then assessed whether occupancy was related to patch size, isolation, vegetation, or presence of water, after correcting for imperfect detection. The mean detection probabilities of water vole signs in autumn (0.71) and winter (0.81) indicated that false absences may be generated in about 20–30% of occupied patches surveyed by a single observer on a single occasion. There was no statistical support for the effects of covariates on detectability. After controlling for imperfect detection, the mean probabilities of occupancy in autumn (0.31) and winter (0.29) were positively related to patch size and presence of water, and negatively so, albeit weakly, to patch isolation. Overall, our study underlined the importance of accounting for imperfect detection in sign surveys of small mammals such as water voles, pointing out the need to use occupancy detection modelling together with replicate surveys for accurately estimating occupancy and the factors affecting it.

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Correlation between genetic parameters and factors such as backfat thickness (BFT), rib eye area (REA), and body weight (BW) were estimated for Canchim beef cattle raised in natural pastures of Brazil. Data from 1648 animals were analyzed using multi-trait (BFT, REA, and BW) animal models by the Bayesian approach. This model included the effects of contemporary group, age, and individual heterozygosity as covariates. In addition, direct additive genetic and random residual effects were also analyzed. Heritability estimated for BFT (0.16), REA (0.50), and BW (0.44) indicated their potential for genetic improvements and response to selection processes. Furthermore, genetic correlations between BW and the remaining traits were high (P > 0.50), suggesting that selection for BW could improve REA and BFT. On the other hand, genetic correlation between BFT and REA was low (P = 0.39 ± 0.17), and included considerable variations, suggesting that these traits can be jointly included as selection criteria without influencing each other. We found that REA and BFT responded to the selection processes, as measured by ultrasound. Therefore, selection for yearling weight results in changes in REA and BFT.