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991.
A sample of 1,004 eighth and tenth grade students in twenty-three small Central/East Texas communities was assessed to determine 1) their perception of the number of their friends who use drugs, 2) the amount of information they received about drugs from their friends, and 3) the connection between those perceptions and drug use. A multiple regression model which included grade, gender, the degree to which friends are perceived to use drugs and the amount of information about drugs received from friends explained 39 percent of the variance in the degree to which rural adolescents were involved in drug use. An item specific analysis of the subcomponents of these composite variables explained 44 percent of the variance in the degree to which rural adolescents were involved in drug use. This same four-factor model accurately classified over 81 percent of non-drug-users and 67 percent of users using discriminant analysis. Students who perceived a higher degree of drug use among their friends and who received more information about drugs from their friends used drugs more frequently. Lower marijuana use in these rural areas as compared to the nation, both as a peer perception and as a fact, may protect these students to a degree from broader patterns of drug use. The findings of this study support the theory that peer pressure is related to drug abuse, even in rural areas. 相似文献
992.
993.
How is the transition to parenthood constructed in a context in which fatherhood and motherhood are therapeutically defined? Relying on ethnographic observations of 66 expectant and new parent couples assigned to 13 different parent educator‐led groups, we show how, with the arrival of a baby, a sense of transition is crafted and often amplified. Our analysis suggests that just as the overall life course is constructed through language and meaningful gesture, so also the transition to parenthood is constructed through verbal and nonverbal signification. Using a vocabulary of contrast and change, parent edu‐cators and expectant and new parents create a collective feeling that they are witnessing a transformation of major proportions. By emphasizing the idea that things are no longer the same, parent educators also establish themselves as authorities whose job it is to steer fathers and mothers through unfamiliar terrain. For their part, expectant and new parents not only listen to but often also replicate the parent educators’ vocabularies and, in so doing, further magnify distinctions between before parenthood and after, and between one stage of parenthood and another. Childbirth stands uncomfortably at the junction of the two worlds of nature and culture. Like death and disease it is a biological event, but the defining feature of biological events in human life is their social character. Ann Oakley (1980:7) 相似文献
994.
Stephen D. Whitney M.S. Emiko A. Tajima Ph.D. Todd I. Herrenkohl Ph.D. Bu Huang Ph.D. 《Child and Adolescent Social Work Journal》2006,23(3):316-342
This study investigated child welfare practitioners’ ratings of the severity of parental discipline practices. Ratings varied by the type of act, age of the child, and by chronicity. Exploratory investigation into changes across time found that current practitioners (N = 27) rated several practices (e.g. spanking and shaking) as more severe than did professionals (N = 24) sampled in 1977. Results underscore the complexity of defining child maltreatment and offer implications for practitioners, applied researchers, and child welfare policy makers.The authors Stephen D. Whitney, Emiko A. Tajima, Todd I. Herrenkohl, and Bu Huang are affiliated with the School of Social Work, University of Washington.Work on this project is supported by funds from the Social Work Prevention Research Center, School of Social Work, University of Washington (National Institute of Mental Health Grant R24MH56599, Lewayne Gilchrist, PI) and by the University of Washington Royalty Research Fund. 相似文献
995.
János Balogh József Békési Gábor Galambos Gerhard Reinelt 《Journal of Combinatorial Optimization》2014,27(1):115-131
Semi-on-line algorithms for the bin-packing problem allow, in contrast to pure on-line algorithms, the use of certain types of additional operations for each step. Examples include repacking, reordering or lookahead before packing the items. Here we define and analyze a semi-on-line algorithm where for each step at most k items can be repacked, for some positive integer k. We prove that the upper bound for the asymptotic competitive ratio of the algorithm is a decreasing function of k, which tends to 3/2 as k goes to infinity. We also establish lower bounds for this ratio and show that the gap between upper and lower bounds is relatively small. 相似文献
996.
Let G be a connected graph with n≥2 vertices. Suppose that a fire breaks out at a vertex v of G. A firefighter starts to protect vertices. At each time interval, the firefighter protects one vertex not yet on fire. At the end of each time interval, the fire spreads to all the unprotected vertices that have a neighbor on fire. Let sn(v) denote the maximum number of vertices in G that the firefighter can save when a fire breaks out at vertex v. The surviving rate ρ(G) of G is defined to be ∑ v∈V(G)sn(v)/n 2, which is the average proportion of saved vertices. In this paper, we show that if G is a planar graph with n≥2 vertices and having girth at least 7, then $\rho(G)>\frac{1}{301}$ . 相似文献
997.
Let k be a positive integer and G=(V,E) be a graph. A vertex subset D of a graph G is called a perfect k-dominating set of G, if every vertex v of G, not in D, is adjacent to exactly k vertices of D. The minimum cardinality of a perfect k-dominating set of G is the perfect k-domination number γ kp (G). In this paper, we give characterizations of graphs for which γ kp (G)=γ(G)+k?2 and prove that the perfect k-domination problem is NP-complete even when restricted to bipartite graphs and chordal graphs. Also, by using dynamic programming techniques, we obtain an algorithm to determine the perfect k-domination number of trees. 相似文献
998.
This paper advances knowledge regarding how fathers and mothers perceive and experience flexible working opportunities. It does this through applying the theoretical concept ‘belonging’ to ‘Parsonian’ classifications of parenting and work. In so doing it makes transparent the misconceptions and inequities which exist among parents and their organizational environments. Focusing initially on a qualitative study of fathers’ experience of working flexibly, the paper shows how fathers felt marginalized from the possibilities of flexible work due to line managers’ assumptions that men belonged to an ‘instrumental’ economic provider group. The paper contributes a new angle to debate by articulating how fathers perceived employed mothers as belonging to an ‘expressive’ child‐oriented group, with privileged access to flexibility. However, drawing upon a study of maternity and flexible work we query fathers’ assumptions that flexibility was easily available to mothers, suggesting that fathers’ perceptions of maternal privilege were misconceived. While mothers were categorized as belonging within an ‘expressive’ group associated with childcare, they were nevertheless discouraged from accessing flexibility. Inequities between women and men (with regard to flexibility) thus appeared to be less significant than fathers supposed. 相似文献
999.
This paper presents a theoretical model to help managers visualise and manage confidential situations more effectively. The model metaphorically likens a confidential setting to the properties of a soap bubble, e.g. elastic expansion or contraction, minimal surface area to contain a given volume, fragility, surface tension, pressure, stress, strain and the potential for bursting thereby releasing the contents to the external environment. We explore the conceptual developments in two phases. Firstly, looking at how a bubble and confidential scenario form and grow. Secondly, we consider how a bubble may burst and map these forces to ways in which confidentiality may be breached. Many attributes are mapped, the key ones being: the embedded value within the system, the criticality of maintaining confidentiality, increasing pressure, the corresponding stress/strain dynamics and the levels of trust between stakeholders. Key research propositions are derived from the model which aims to minimise the risk of a confidentiality breach. 相似文献
1000.