Iterative Converging Algorithms for Computing Bounds on Durations of Activities in Pert and Pert-Like Models

Since its invention in 1958, Program Evaluation and Review Technique (PERT) has been widely used during the planning, design, and implementation of projects. Pert models the activities of a project as a single source-single sink directed acyclic graph where nodes represent events (end or beginning of activities) and arcs activities. The maximum amount by which an activity can be delayed without delaying the overall project is called the slack. Critical tasks have zero slack whereas all noncritical tasks have positive slacks. Pert is a valuable tool in the management of large projects since it allows to compute the slack of each activity of the project. Such information may be crucial in avoiding cost overruns that would be caused by delays to critical activities and/or excessive delays to noncritical activities. What Pert fails to provide is how one should go about distributing remaining slack on noncritical activities while taking into consideration properties of the activities as well as precedence relationships among them, so as to have reasonable upper bounds on duration of all activities, critical or noncritical. In this paper we propose several algorithms for the distribution of slack on non-critical activities. We show that if one desires to distribute the remaining slack proportionally to the initially assigned activity durations then the problem is in P, and propose an algorithm of linear time complexity. However if one desires to use distribution functions other than the initial durations of activities, then the problem of slack distribution becomes NP-complete. Finding the maximal bounds corresponding to zero-slack solution at the sink requires iterative application of exponential algorithm. For that case we introduce an approximation algorithm of linear time complexity on each iteration. The algorithm iteratively increases bounds on durations of activities and converges to the zero-slack solution on all paths from the source node to the sink node in the Pert-like graph. The algorithms described in this paper were successfully applied to solving timing bounds problems in VLSI design.     

Family environment in Hispanic college females with a history of childhood sexual abuse

This study sought to examine the family environments of a sample of Hispanic women who reported childhood sexual abuse. Eighteen women, taken from a larger college sample, were individually interviewed and administered the Family Environment Scale (FES; Moos & Moos, 1994). Cultural values and the relationship of family characteristics to the individual's experience of sexual abuse were explored. The abused women obtained significantly higher scores on the Achievement-Orientation subscale of the FES than the normative group. Qualitative data revealed some patterns in these families regarding sexual discussions and poor conflict resolution skills. Implications for treatment of Hispanic victims are discussed.     

POLICY-COMPARING SIMULATION EXPERIMENTS: DESIGN AND ANALYSIS

One of the principal uses of simulation in business and industry is to compare alternative policies or decision rules for the operation and control of complex systems. The immediate objective of such simulation studies is usually quite simple: to discover the best of the several policies under consideration. The measure of effectiveness used is also usually straightforward, often dollars of cost or profit. The basic experimental design that will produce the best comparison of alternatives is generally agreed upon: all policies should be compared under, to the extent possible, identical experimental conditions, i.e., when randomness is involved, all alternatives in a simulation experiment should be simulated using a common sequence of randomly-generated events.     

Children Exposed to Community Violence: Issues for Assessment and Treatment

Community violence is increasingly recognized as a risk factor for serious psychological problems with children particularly vulnerable to its effects. This article summarizes the existing knowledge on the effects of chronic exposure to community violence, highlights essential issues in assessing children for both exposure and resulting trauma from community violence, and provides treatment guidelines for those affected children.     

Household adversity and food security: The case of youth in public housing neighborhoods

This paper sets out to explore factors that may be associated with food hardship among young people who reside in public housing (N?=?124). The study is guided by Family Stress Theory and uses data from a cross-sectional study of African–American adolescents living in a public housing neighborhood located in West Baltimore. Results suggest that food security (defined as availability, accessibility, and adequacy) was negatively related to mother’s incarceration, large households, household experiencing material hardships, and interpersonal conflict as well as violence. It was also linked to community disorganization. Program and policy implications are suggested.     

Partner Violence Victimization Among Lesbian,Gay, Bisexual,Transgender, and Queer Youth: Associations Among Risk Factors

Literature shows that youth who identify as lesbian, gay, bisexual, transgender, or queer (LGBTQ) experience high rates of victimization across various contexts, though there is little research specific to partner violence victimization. Given the deleterious effects of partner violence seen in both youth generally and LGBTQ adults, it is imperative to investigate partner violence among LGBTQ youth. The authors investigated the prevalence of partner violence among a community sample of LGBTQ youth (N = 140) and examined potential correlates of said violence. Approximately half of the participants had ever experienced some form of partner violence. Rates of ever experiencing partner violence were approximately 2.5 times higher for youth who had binge drank in the past month or ever experienced familial abuse and nearly three times higher for youth who had experienced an episode of homelessness in the past year. Implications for professionals who serve LGBTQ youth are discussed.     

Ergonomics analyses of five joineries located in Florianópolis-SC, using the LEST Method

Considering the goal of Ergonomic Work Analysis to establish, from the point of view of workers, safe, healthy, comfortable and efficient environments, this study propose to analyze the work situation of machine operators at five joineries from Florianópolis-SC. For this, it was applied the LEST Method to evaluate the task made by the operators, considering the physical, cognitive and organizational work environment. As results, it was identified the main ergonomics problems of these workstations, presenting an ergonomic diagnosis and their implications on health and safety of workers. As result, it was concluded that the main ergonomics problems at joineries are related with noise, with constant load of weight and with the postures taken. Besides these problems, others were diagnosed, for example, the pressure for workers to comply strictly the task stipulated and also the poor training and capacity of workers.