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Given a directed simple graph \(G=(V,E)\) and a cost function \(c:E \rightarrow R_+\), the power of a vertex \(u\) in a directed spanning subgraph \(H\) is given by \(p_H(u) = \max _{uv \in E(H)} c(uv)\), and corresponds to the energy consumption required for wireless node \(u\) to transmit to all nodes \(v\) with \(uv \in E(H)\). The power of \(H\) is given by \(p(H) = \sum _{u \in V} p_H(u)\). Power Assignment seeks to minimize \(p(H)\) while \(H\) satisfies some connectivity constraint. In this paper, we assume \(E\) is bidirected (for every directed edge \(e \in E\), the opposite edge exists and has the same cost), while \(H\) is required to be strongly connected. Moreover, we assume \(c:E \rightarrow \{A,B\}\), where \(0 \le A < B\). We improve the best known approximation ratio from 1.75 (Chen et al. IEEE GLOBECOM 2005) to \(\pi ^2/6 - 1/36 + \epsilon \le 1.61\) using an adaptation of the algorithm developed by Khuller et al. [SIAM J Comput 24(4):859–872 1995, Discr Appl Math 69(3):281–289 1996] for (unweighted) Minimum Strongly Connected Subgraph.  相似文献   
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Research in revenue management is rapidly changing as the environment in which firms operate changes. The Internet, the adoption of new information technologies, and other market forces are driving a new wave of research in revenue management. At the same time, more and more industries are adapting the tools of revenue management to their needs. Promising research directions are more sophisticated models of consumer behavior, more general models and understanding of rivalry, and more general pricing mechanisms. These are important issues for today's revenue managers and promising areas for both theoretical and empirical research.  相似文献   
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ABSTRACT

This study aims to understand the importance of embracing and promoting inclusiveness in higher education as a path to academic excellence. As student populations become increasingly diverse and higher education faces significant challenges at home and abroad, cultural competence – understanding the specific culture, language, social, and economic status of people-, becomes more important than ever before because a sense of belonging is essential for students. This study is to re-envision diversity and practice our commitment to inclusive excellence-both preparing students with a quality learning opportunity and facilitating a sense of belonging by providing an embracing environment on campus.  相似文献   
35.
Most undergraduate students pursue a social work major because of their desire to help others. Students tend to be more interested in doing than in understanding the research and knowledge of the profession and the complexities of social work practice. Instructors are often faced with the challenge of enhancing student motivation to learn challenging course material. This study explored student perceptions of instructor influences on their motivation and engagement in learning. Through online surveys, students described their experiences of being known and how those experiences affected their participation in practice, research, and human behavior in the social environment courses. Results showed that instructor caring (providing recognition, expressing relational qualities, and responding to students) positively influences student motivation and affective learning by increasing comfort, willingness to ask questions, take risks, and overall participation. Conversely, of those who reported mixed experiences or who felt unknown, most reported a negative impact on their motivation and participation. These findings suggest that social work faculty can influence student motivation and engagement with essential social work curriculum by expressing care and helping students feel known in the classroom.  相似文献   
36.
Single motherhood in sub-Saharan Africa has received surprisingly little attention, although it is widespread and has critical implications for children’s well-being. Using survival analysis techniques, we estimate the probability of becoming a single mother over women’s life course and investigate the relationship between single motherhood and child mortality in 11 countries in sub-Saharan Africa. Although a mere 5 % of women in Ethiopia have a premarital birth, one in three women in Liberia will become mothers before first marriage. Compared with children whose parents were married, children born to never-married single mothers were significantly more likely to die before age 5 in six countries (odds ratios range from 1.36 in Nigeria to 2.61 in Zimbabwe). In addition, up to 50 % of women will become single mothers as a consequence of divorce or widowhood. In nine countries, having a formerly married mother was associated with a significantly higher risk of dying (odds ratios range from 1.29 in Zambia to 1.75 in Kenya) relative to having married parents. Children of divorced women typically had the poorest outcomes. These results highlight the vulnerability of children with single mothers and suggest that policies aimed at supporting single mothers could help to further reduce child mortality in sub-Saharan Africa.  相似文献   
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Unusual events, beyond mere coincidences, may occur during the course of psychotherapy. Yet, clinical training often does not prepare therapists how to understand and potentially engage with these encounters. The aim of this report is to explore the emergence of synchronistic events in therapy, while providing two clinical case composites to illustrate the author’s central points. Drawing on the Celtic concept of “thin places,” a new understanding of synchronicities and the therapeutic relationship is offered.  相似文献   
39.
This cross-sectional study aimed to assess the impact of age and gender on 4 measures of grip and pinch force of well elderly community dwellers and to provide normative values. The hypotheses were that age and gender affect pinch and grip force and that these 2 factors might interact. Hand strength of 224 seniors 65-92 years old was tested. Grip and pinch force decreased in successively older age groups past 65 years. Men's grip force exceeded that of women in all age groups. Men's hand-force decline was steeper than that of women over successive age groups, suggesting that gender differences in force decreased with age. Trends were the same for all 4 types of grip- and pinch-force measurement but were most clearly visible in grip and key-pinch force. Norms were provided for seniors age 65-85+ years in 5-yr increments.  相似文献   
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