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991.
Child protective services (CPS) case records of 639 children placed in out-of-home care due to maltreatment were reviewed, and substance abuse by the child's caregiver prior to the child's placement was evaluated systematically. Based on several different sources of information, 79% of the caregivers were found to meet the criteria for caregiver substance abuse (CSA). Children with and without evidence of CSA differed on age, ethnicity, family composition, and type of maltreatment. The importance of operational specificity in defining CSA and implications for policy and service delivery are discussed. 相似文献
992.
Bathtub distributions are characterized by bathtub failure rate functions . These are possibly more realisitic models than the monotone failure rate models . A systematic account of such distributions is not available and this review aims to give such an account . We give some easily verifiable conditions to check the bathtub property of a distribution along with methods to construct such distributions . We also discuss some stochastic and reliablity mechanisms which lead to bathtub distributions. These include mixtures ( stochastic failure rate models ) , series system , stochastic differential equation models and so on. We also review inference on bathtub distributions. The paper concludes with a rather exhaustive list of bathtub distributions. 相似文献
993.
Ruth A. Hopkins M.B.A. Karen M. Demartin Clifford B. Reifler M.D. 《Journal of American college health : J of ACH》2013,61(2):76-80
Abstract “A Double-Blind Study of Oral Acyclovir for Suppression of Recurrences of Genital Herpes Simplex Virus Infection,” JOHN M. DOUGLAS, et al. Patients with frequently recurring genital herpes were enrolled in a double-blind placebo-controlled trial comparing 200-mg acyclovir capsules, given five or two times daily, with placebo. Of 47 placebo recipients, 44 (94 per cent) had recurrences during the 120-day treatment period, compared with 13 (29 per cent) of 45 patients treated with acyclovir five times daily and 18 of 51 (35 per cent) treated with acyclovir twice daily (P < 0.001 for each regimen compared with placebo). The median time to the first clincial recurrence was 18 days in placebo recipients, compared with over 120 days in both acyclovir-treated groups (P < 0.001 for both groups compared with placebo). The mean monthly recurrence rate during the medication period was 0.86 in placebo recipients, compared with 0.13 in patients treated with acyclovir five times daily and 0.14 in patients treated with acyclovir twice daily (P < 0.001 for both groups compared with placebo). While receiving therapy, 86 of 96 acyclovir-treated patients had over a 50 per cent reduction in their pretreatment recurrence rate. Breakthrough recurrences in acyclovir recipients were of shorter duration and associated with a lower frequency of viral shedding than recurrences in placebo recipients. After medication was discontinued, the subsequent recurrence rate returned to pretreatment frequencies. Daily oral acyclovir was well tolerated. We conclude that oral acyclovir given for four months markedly reduces but does not completely prevent recurrences of genital herpes and does not influence the long-term natural history of the disease. (New England Journal of Medicine 1984 July;310:1551–6.) 相似文献
994.
Some improved ratio type estimators of population mean and ratio in finite population sample surveys
B. Prasad 《统计学通讯:理论与方法》2013,42(1):379-392
In this paper we present a class of ratio type estimators of the population mean and ratio in a finite population sample surveys with without replacement simple random sampling design, where information on an auxiliary variate x positively correlated with the main variate y is available. Large sample approximations to mean square errors (MSE) of these estimatorsare evaluated and their MSE's are compared with the MSE of the usual ratio estimator [ybar]R of [ybar] the population mean of y. It is shown that under certain conditions these estimators are more efficient than [ybar]R. When a prior knowledge of the value of thecoefficient of variation, cy, of y is at hand, ratio type estimator, say [ybar]1 of [ybar] is proposed. It is shown, under certain conditions, that [ybar]1 is more efficient than [ybar]R. When values of cy, cx and the population correlation coefficient ρ is at hand, then we have proposed another estimator, say [ybar]2 of [ybar], which is always better than [ybar]R as far as the efficiency is concerned. In fact, is [ybar] 2 is shown to be even better than [ybar]1. Finally estimators better than the usual ratio estimator [ybar]/[xbar] of [Ybar] are given. 相似文献
995.
For testing the equality of K-populations against ordered alternatives a quadratic form based on two-sample scores of (K-l) pairs of adjacent samples has been suggested as an alternative to the statistic proposed by Beslow(1970). The Pitman asymptotic efficiency of the proposed statistic relative to the Breslow's statistic is found to be one or very close to one in all cases considered. The Bahadur asymptotic efficiency has also been studied and found to be at least one for the situations taken up in this paper. 相似文献
996.
997.
998.
Miranda Witvliet Tjeert Olthof Jan B. Hoeksma Frits A. Goossens Marieke S. I. Smits Hans M. Koot 《Social Development》2010,19(2):285-303
To understand children's peer group affiliation, this study examined to what extent children in naturally occurring groups resemble each other on bullying, likeability, and perceived popularity. Participants were fourth‐ to sixth‐grade pupils (N = 461). Peer groups were identified using the social cognitive map procedure. Resemblance on bullying, likeability, and perceived popularity was evaluated by means of variance components models. Resemblance in peer groups was strongest for perceived popularity, followed by bullying and likeability. Moreover, resemblance on bullying could for a large part be attributed to the high‐perceived popularity of the group, and to a lesser extent, to the low likeability of the group. It is concluded that children showing bullying seem to affiliate with each other most of all to attain or maintain their position in a perceived popular peer group. Results stress the importance of considering the functionality of bullying from a group perspective. 相似文献
999.
Juvenile delinquency and high risk behaviors have been linked to disturbances in attachment. The present study examined parent
and peer attachment in 67 African American males and 97 Latinos (ages 12–17, M = 14.7 ± 1.3) attending an alternative school.
The Inventory of Parent and Peer Attachment was used to identify 3 attachment style groups: “Isolated,” “Disconnected,” and
“Connected.” Controlling for age, attachment group membership predicted differences in delinquent behaviors, as did ethnicity.
Further, on the Youth Self-Report of the Child Behavior Checklist, attachment group membership predicted differences in both
the Internalizing and Externalizing Scales. Implications for interventions with each identified attachment group are discussed. 相似文献
1000.
This article is based on a quantitative risk assessment (QRA) that was performed on a radioactive waste disposal area within the Western New York Nuclear Service Center in western New York State. The QRA results were instrumental in the decision by the New York State Energy Research and Development Authority to support a strategy of in‐place management of the disposal area for another decade. The QRA methodology adopted for this first of a kind application was a scenario‐based approach in the framework of the triplet definition of risk (scenarios, likelihoods, consequences). The measure of risk is the frequency of occurrence of different levels of radiation dose to humans at prescribed locations. The risk from each scenario is determined by (1) the frequency of disruptive events or natural processes that cause a release of radioactive materials from the disposal area; (2) the physical form, quantity, and radionuclide content of the material that is released during each scenario; (3) distribution, dilution, and deposition of the released materials throughout the environment surrounding the disposal area; and (4) public exposure to the distributed material and the accumulated radiation dose from that exposure. The risks of the individual scenarios are assembled into a representation of the risk from the disposal area. In addition to quantifying the total risk to the public, the analysis ranks the importance of each contributing scenario, which facilitates taking corrective actions and implementing effective risk management. Perhaps most importantly, quantification of the uncertainties is an intrinsic part of the risk results. This approach to safety analysis has demonstrated many advantages of applying QRA principles to assessing the risk of facilities involving hazardous materials. 相似文献