We consider the one-sided and the two-sided first-exit problem for a compound Poisson process with linear deterministic decrease between positive and negative jumps. This process (X(t))t≥0 occurs as the workload process of a single-server queueing system with random workload removal, which we denote by M/Gu/Gd/1, where Gu(Gd) stands for the distribution of the upward (downward) jumps; other applications are to cash management, dams, and several related fields. Under various conditions on Gu and Gd (assuming e.g. that one of them is hyperexponential, Erlang or Coxian), we derive the joint distribution of τy=inf{t≥0|X(t)?(0,y)}, y>0, and X(τy) as well as that of T=inf{t≥0|X(t)≤0} and X(T). We also determine the distribution of sup{X(t)|0≤t≤T}. 相似文献
A case–control study of lung cancer mortality in U.S. railroad workers in jobs with and without diesel exhaust exposure is reanalyzed using a new threshold regression methodology. The study included 1256 workers who died of lung cancer and 2385 controls who died primarily of circulatory system diseases. Diesel exhaust exposure was assessed using railroad job history from the US Railroad Retirement Board and an industrial hygiene survey. Smoking habits were available from next-of-kin and potential asbestos exposure was assessed by job history review. The new analysis reassesses lung cancer mortality and examines circulatory system disease mortality. Jobs with regular exposure to diesel exhaust had a survival pattern characterized by an initial delay in mortality, followed by a rapid deterioration of health prior to death. The pattern is seen in subjects dying of lung cancer, circulatory system diseases, and other causes. The unique pattern is illustrated using a new type of Kaplan–Meier survival plot in which the time scale represents a measure of disease progression rather than calendar time. The disease progression scale accounts for a healthy-worker effect when describing the effects of cumulative exposures on mortality. 相似文献
We address the staff rostering problem in call centers with the goal of balancing operational cost, agent satisfaction and customer service objectives. In metropolitan cities such as Istanbul and Mumbai, call centers provide the transportation of their staff so that shuttle costs constitute a significant part of the operational costs. We develop a mixed integer programming model that incorporates the shuttle requirements at the beginning and end of the shifts into the agent-shift assignment decisions, while considering the skill sets of the agents, and other constraints due to workforce regulations and agent preferences. We analyze model solutions for a banking call center under various management priorities to understand the interactions among the conflicting objectives. We show that considering transportation costs as well as agent preferences in agent-shift assignments provides significant benefits in terms of both cost savings and employee satisfaction. 相似文献
ABSTRACTIn Hungary, until the end of the 1940s, there were two main established methods of occupying the mentally ill who were fit for work. From the end of the nineteenth century, a lesser number of patients underwent work therapy in mental asylums, whereas the others were treated with so-called family therapy (otherwise known as the heterofamilial system), exploiting the capacities of families in the countryside. As an important part of this, the mentally ill helped in housekeeping and agricultural work. However, following the political and ideological turn of 1948, the latter form of treatment became debated, and then it was gradually superseded. Parallel to this process, work therapy came to be the most popular type of treatment for mental illnesses, as work formed the basis of the ideology of the communist state, and thus, healing through work harmonized with the general tendencies of the era. This article examines texts related to work therapy published in neurological–psychiatric and psychological journals and monographs between 1954 and 1964. However, although work therapy appeared to be the “handmaiden of ideology,” and even though it was supposed to fulfil a particular role, in reality, the role and perception of work therapy were a lot more complicated. 相似文献
Researchers have proposed that work-family policy use may either reinforce or challenge the existing gendered division of
labor within couples, but results from prior studies have been inconclusive. Using data from a regional survey of work and
family life, we extend this research by focusing on how housework is divided within couples and by differentiating between
traditionally female- and male- typed housework tasks. Results show that among dual-earning women, policy use is not related to share of female- or male-typed
tasks. Among dual-earning men, policy use is positively related to share of female-typed tasks and negatively related to share
of male-typed tasks. These findings suggest that work-family policy use does not reinforce the gendered division of housework.
This article argues that social work in the UK needs to renegotiate its relationship with community welfare agencies. It begins by examining what we mean by local community and how welfare needs reflect complex non-linear dynamics unique to the local circumstances. It is argued that these are not always recognised in centralised policy agendas. The article broadly draws a parallel between policy issues for the European Community and for the national state. The drive for both is towards uniformity, which potentially fails to acknowledge the unique circumstances at both the national level between nations and the local level between communities.
The focus of the analysis is the lack of engagement with the subtleties of the local within the arena of social work education and practice. With the opportunity presented by the introduction of a new social work degree in the UK, the authors describe how a social work programme in Liverpool undertook a piece of research with the aim of creating an appropriate place for community welfare agencies in practice placements, the academic curriculum and, ultimately, with the next generation of social work practitioners. Eight welfare agencies within the proximity of Liverpool University, an area known as Toxteth, agreed to participate in the research to investigate what kind of placement module would enable local welfare agencies to engage meaningfully in the social work degree. Out of this process emerged a model for research based curriculum development involving local community agencies and academic institutions. More specifically for Liverpool, it placed the notion of social work's relationship with local community welfare at the heart of professional development for qualifying social workers, paving the way in this region of England for closer links between welfare agencies associated with civil society and professional social workers. 相似文献
This article presents the findings of a four-year survey on the development of social work education in Russia from 1995 to the present day. Through a series of questionnaires, interviews and discussions with Russian academics, practitioners and students, the study looks at a variety of issues including the high rate of attrition. It focuses on aspects of students’ practice placements such as the type, length and quality of practice placements, the students’ workload and the supervision provided. It also looks at the contribution that international collaboration has made to the development of social work education in Russia.
The survey concludes that there is a need to enhance the overall package for social workers and raise the status of the profession in order to retain qualified personnel. Longer practice placements which start in the first year and are adequately funded and supervised are seen as the key to retaining new graduates. It concludes that although international projects have made a difference to those participating at the time, it is difficult to disseminate these benefits beyond the immediate region. Now that international funding to Russia has been reduced it is critical that any remaining funding is accurately targeted and properly coordinated. 相似文献