Objective: We conducted a cohort study of recent wartime veterans to determine the postservice mortality risk due to motor vehicle accidents (MVAs).
Methods: Veterans were identified from the Defense Manpower Data Center records. Deployment to te Iraq or Afghanistan war zone was determined from the Contingency Tracking System. Vital status of 317,581 deployed and 964,493 nondeployed veterans was followed from their discharge dates between 2001 to 2007 until earlier of date of death or December 31, 2009. Underlying causes of death were obtained from the National Death Index Plus.
Results: Based on 9,353 deaths (deployed, 1,650; nondeployed, 7,703), of which 779 were MVA deaths as drivers (166; 613), both cohorts had 25 to 24% lower mortality risk from all causes but had 44 to 45% higher risk of MVA deaths relative to the U.S. general population. The higher MVA mortality risk was not associated with deployment to the war zone. After controlling for age, sex, race, marital status, branch of service, and rank, the risk for deployed veterans was comparable to that of nondeployed veterans (hazard ratio = 0.91; 95% confidence interval, 0.77–1.09).
Conclusions: Veterans exhibit significantly higher risk of MVA deaths compared to the U.S. general population. However, deployment to the Iraq or Afghanistan war was not associated with the excess risk. 相似文献
Studies on the population structure and dynamics of the stone centipede Monotarsobius curtipes C. Koch in soils of the northern Kola Peninsula have shown that, with respect to abundance and biomass, this species is a dominant of the soil macrofauna and, in particular, of the trophic group of zoophages. Life in high northern latitudes does not disturb the sex and age structure of populations but limits the reproductive activity of these centipedes. Specific biological features of M. curtipes at the northern periphery of its range include the absence of repeated breeding, completion of several developmental (age) stages within a short growing season, and long ontogeny involving several winterings. 相似文献
Measurements of low-level radioactivity often give results of the order of the detection limit. For many applications, interest is not only in estimating activity concentrations of a single radioactive isotope, but focuses on multi-isotope analyses, which often enable inference on the source of the activity detected (e.g. from activity ratios). Obviously, such conclusions become questionable if the measurement merely gives a detection limit for a specific isotope. This is particularly relevant if the presence of an isotope, which shows a low signal only (e.g. due to a short half-life or a small transition probability), is crucial for gaining the information of interest. 相似文献
In some fishes, water chemistry or temperature affects sex determination or creates sex‐specific selection pressures. The resulting population sex ratios are hard to predict from laboratory studies if the environmental triggers interact with other factors, whereas in field studies, singular observations of unusual sex ratios may be particularly prone to selective reporting. Long‐term monitoring largely avoids these problems. We studied a population of grayling (Thymallus thymallus) in Lake Thun, Switzerland, that has been monitored since 1948. Samples of spawning fish have been caught about 3 times/week around spawning season, and water temperature at the spawning site has been continuously recorded since 1970. We used scale samples collected in different years to determine the average age of spawners (for life‐stage specific analyses) and to identify the cohort born in 2003 (an extraordinarily warm year). Recent tissue samples were genotyped on microsatellite markers to test for genetic bottlenecks in the past and to estimate the genetically effective population size (Ne). Operational sex ratios changed from approximately 65% males before 1993 to approximately 85% males from 1993 to 2011. Sex ratios correlated with the water temperatures the fish experienced in their first year of life. Sex ratios were best explained by the average temperature juvenile fish experienced during their first summer. Grayling abundance is declining, but we found no evidence of a strong genetic bottleneck that would explain the apparent lack of evolutionary response to the unequal sex ratio. Results of other studies show no evidence of endocrine disruptors in the study area. Our findings suggest temperature affects population sex ratio and thereby contributes to population decline. Persistencia de Proporción de Sexos Desigual en una Población de Tímalos (Salmonidae) y el Posible Papel del Incremento de la Temperatura 相似文献
Abstract: Although there has been a call for the integration of behavioral ecology and conservation biology, there are few tools currently available to achieve this integration. Explicitly including information about behavioral strategies in population viability analyses may enhance the ability of conservation biologists to understand and estimate patterns of extinction risk. Nevertheless, most behavioral‐based PVA approaches require detailed individual‐based data that are rarely available for imperiled species. We present a mechanistic approach that incorporates spatial and demographic consequences of behavioral strategies into population models used for conservation. We developed a stage‐structured matrix model that includes the costs and benefits of movement associated with 2 habitat‐selection strategies (philopatry and direct assessment). Using a life table for California sea lions (Zalophus californianus), we explored the sensitivity of model predictions to the inclusion of these behavioral parameters. Including behavioral information dramatically changed predicted population sizes, model dynamics, and the expected distribution of individuals among sites. Estimated population sizes projected in 100 years diverged up to 1 order of magnitude among scenarios that assumed different movement behavior. Scenarios also exhibited different model dynamics that ranged from stable equilibria to cycles or extinction. These results suggest that inclusion of behavioral data in viability models may improve estimates of extinction risk for imperiled species. Our approach provides a simple method for incorporating spatial and demographic consequences of behavioral strategies into population models and may be easily extended to other species and behaviors to understand the mechanisms of population dynamics for imperiled populations.相似文献