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981.
This article reports on the survey component of a study examining urban high school students' experiences with violence. The survey's purpose was to collect information on students' experiences with violence, explore gender differences, and identify which factors are associated with the self-reported use of violence. Two prominent risk factors for the self-reported use of violence were found: having a close friend or family member injured by violence, and gun possession. Young men and women did not differ significantly in overall exposure, victimization, and perpetration. However, gender clearly informed the types of violence reported. The findings offer practical strategies for addressing adolescent violence, such as reducing gun availability and community-level violence, but future research must further examine the role of gender in order to structure more effective prevention and intervention approaches that target different kinds of violence. 相似文献
982.
Millions of workers suffer from upper extremity (musculoskeletal) disorders. Many of these workers are predisposed to upper extremity musculoskeletal disorders because of early exposure to ergonomic risks as students. Computer usage for four or more hours remains the greatest risk for upper extremity musculoskeletal disorders for workers and students alike. Developing preventative methods to reduce student exposure, and thus protect future workers from upper extremity musculoskeletal disorders later in life, requires an appropriate measure for upper extremity musculoskeletal disorder prevalence and related limitations for student functioning. Item response theory analysis was used to evaluate and further develop a upper extremity functioning scale for the student role. 相似文献
983.
Given the emerging interest among researchers, practitioners, and policymakers in youth participation, it is important to examine and assess carefully the promise and challenges of youth engagement. 相似文献
984.
Mutations in the muscle protein titin have been linked to dilated cardiomyopathy, a condition in which the heart chambers are enlarged and blood is ineffectively pumped, in humans and in animal models. This protein, which is a component of sarcomeres, provides essential scaffolding for other muscle proteins and acts as a spring to confer passive elasticity on the cardiomyocyte. Several titin isoforms exist, and they display varying size and degrees of elasticity. We review two interesting reports that show how variations in titin isoforms might be implicated in cardiac failure. 相似文献
985.
Hoopes LL 《Science of aging knowledge environment : SAGE KE》2002,2002(45):vp6
The error catastrophe theory of aging, proposed by Orgel in 1963, predicted a decrease in the fidelity of information transfer that accelerated as aging progressed, until properly functioning macromolecules could no longer be reliably made. The theory was extensively tested by comparing DNA polymerases, transfer RNAs, and proteins derived from aging versus young animals, but it did not prove to have general applicability to the process of aging. Recently, the heritable eye disorder progressive external ophthalmoplegia has been found to result from mutation of the gene encoding DNA polymerase gamma, which replicates mitochondrial DNA. The mutant form of the polymerase replicates DNA less accurately than the wild-type enzyme, providing an explanation for the accumulation of mutations in the mitochondrial DNA of patients with this disorder. The affected mitochondria appear to exhibit an age-dependent error catastrophe. It is possible that other genetic diseases might result in error catastrophes in mitochondria as well. 相似文献
986.
Choice of Parametric Accelerated Life and Proportional Hazards Models for Survival Data: Asymptotic Results 总被引:1,自引:0,他引:1
We discuss the impact of misspecifying fully parametric proportional hazards and accelerated life models. For the uncensored case, misspecified accelerated life models give asymptotically unbiased estimates of covariate effect, but the shape and scale parameters depend on the misspecification. The covariate, shape and scale parameters differ in the censored case. Parametric proportional hazards models do not have a sound justification for general use: estimates from misspecified models can be very biased, and misleading results for the shape of the hazard function can arise. Misspecified survival functions are more biased at the extremes than the centre. Asymptotic and first order results are compared. If a model is misspecified, the size of Wald tests will be underestimated. Use of the sandwich estimator of standard error gives tests of the correct size, but misspecification leads to a loss of power. Accelerated life models are more robust to misspecification because of their log-linear form. In preliminary data analysis, practitioners should investigate proportional hazards and accelerated life models; software is readily available for several such models. 相似文献
987.
Probabilistic risk analyses often construct multistage chance trees to estimate the joint probability of compound events. If random measurement error is associated with some or all of the estimates, we show that resulting estimates of joint probability may be highly skewed. Joint probability estimates based on the analysis of multistage chance trees are more likely than not to be below the true probability of adverse events, but will sometimes substantially overestimate them. In contexts such as insurance markets for environmental risks, skewed distributions of risk estimates amplify the "winner's curse" so that the estimated risk premium for low-probability events is likely to be lower than the normative value. Skewness may result even in unbiased estimators of expected value from simple lotteries, if measurement error is associated with both the probability and pay-off terms. Further, skewness may occur even if the error associated with these two estimates is symmetrically distributed. Under certain circumstances, skewed estimates of expected value may result in risk-neutral decisionmakers exhibiting a tendency to choose a certainty equivalent over a lottery of equal expected value, or vice versa. We show that when distributions of estimates of expected value are, positively skewed, under certain circumstances it will be optimal to choose lotteries with nominal values lower than the value of apparently superior certainty equivalents. Extending the previous work of Goodman (1960), we provide an exact formula for the skewness of products. 相似文献
988.
Schenke R Berkowitz E Ludden JM Gaintner JR Hickey ME Hodge RH Randolph LM 《Physician executive》2001,27(2):8-11
The Leading Beyond the Bottom Line article series has received an overwhelming response from ACPE members, mostly in enthusiastic support of this new leadership concept. Some of the important questions raised by members are presented with answers from the authors. This article also explores the moral challenge of leadership and why health care is more than a business. In recent years, there's been confusion about the role of the health care enterprise, its leadership and its management. We have lost our way about the "moral" thing, the "right" thing, because we have no philosophy to guide us. To manage or lead in this "business" of health care, a philosophy is required that recognizes the multiple elements to which the leader has responsibility and obligations: the customers, community, employees, and, certainly, the financial assets. 相似文献
989.
Securing excellent care and positive outcomes for seriously ill, high-risk patients requires extraordinary measures. A health system in Georgia is experiencing strong results by taking a team approach to health care with case managers, physicians and patients working together. 相似文献
990.