A simulation study of a discrete-time multiserver retrial queue with finite population

In this paper, we deal with a discrete-time multiserver retrial queue with finite population. Firstly, we study the Markov chain at the epochs immediately after slot boundaries making emphasis on the computation of its steady-state distribution. Then, the main performance measures are investigated. Besides, we simulate the waiting time of a customer in the retrial group under three different queueing policies. Some numerical examples are given to illustrate the analysis.     

Asthma Patients' Activities and Air Pollution: A Semiparametric Censored Regression Analysis

Asthma patients' health status may be especially sensitive to some types of air pollution, but the evidence on this is mixed. We explore the effects of ground-level ozone on asthma patient's activities, breaking apart the usual aggregated category of leisure into indoor and outdoor activities, and differentiating those by whether the activities were active or inactive. Applying the semiparametric censored estimation method we demonstrate that even though the period over which activities were observed was relatively low in ozone levels, there is a significant impact of ozone on a few activities. The (non-ozone) economic and demographic variables in the model play significant roles in explaining the allocation of time among seven activities, suggesting the suitability of the approach for other household decision-making contexts.     

Bayesian locally optimal design of knockout tournaments

The elimination or knockout format is one of the most common designs for pairing competitors in tournaments and leagues. In each round of a knockout tournament, the losers are eliminated while the winners advance to the next round. Typically, the goal of such a design is to identify the overall best player. Using a common probability model for expressing relative player strengths, we develop an adaptive approach to pairing players each round in which the probability that the best player advances to the next round is maximized. We evaluate our method using simulated game outcomes under several data-generating mechanisms, and compare it to random pairings, to the standard knockout format, and to two variants of the standard format.     

Disabled people's attitudes toward other impairment groups: a hierarchy of impairments

This article seeks to explore, through the literature, the notion that a hierarchy of impairment exists from the perspectives of both disabled and non-disabled people. The literature suggests that disabled people, like non-disabled people, do not always wish to be associated with other impairment groups for a variety of complex reasons, including competing for scarce allocations of funding/resources, sexual attraction, stigma, etc. The article concludes that further research is required in relation to disabled people's attitudes toward other disabled people, in general, and other impairment groups. Such research would expand our knowledge with respect to the degree to which disabled people view themselves as a homogenous in-group, as a set of separate impairment groups, or viewing impairment as only one facet of identity. These findings would help the disability movement to achieve greater inclusiveness amongst different impairments.     

The Impact of Maternal Characteristics and Sensitivity on the Concordance Between Maternal Reports and Laboratory Observations of Infant Negative Emotionality

The moderating role of maternal characteristics and maternal sensitivity on the concordance between maternal reports and laboratory observations of negative emotionality was examined. Participants were 90 primiparous mothers and their infants. Mothers completed questionnaires about remembered care from their own parents and their depressive symptoms prenatally, infant temperament (distress to novelty and distress to limitations), and depressive symptoms postnatally. Mothers and infants participated in a laboratory assessment of infant temperament (distress to novelty and limitations) and maternal sensitivity at 6 months postpartum. Several factors that moderate the degree of concordance between maternal reports and behavioral observations were identified, as predicted. Novelty concordance was higher when mothers reported having their emotional needs met in childhood and low prenatal depressive symptoms. Limitations concordance was higher when mothers were less sensitive during the observational tasks. Methodological and theoretical implications are discussed.     

Joint tests of non-nested models and general error specifications

This paper is concerned with joint tests of non-nested models and simultaneous departures from homoskedasticity, serial independence and normality of the disturbance terms. Locally equivalent alternative models are used to construct joint tests since they provide a convenient way to incorporate more than one type of departure from the classical conditions. The joint tests represent a simple asymptotic solution to the “pre-testing” problem in the context of non-nested linear regression models. Our simulation results indicate that the proposed tests have good finite sample properties.     

Complex belief-desire reasoning in children

Previous research concerned with children's belief-desire psychology has examined the capacity to predict or interpret action on the basis of the implicit proposition that ‘when an actor desires a particular end and believes that a particular action will achieve that end, he or she will undertake that action’. The limitations of this formulation for understanding acts of omission are outlined and an elaborated version of belief-desire psychology introduced. This version holds that ‘when an actor desires a particular end and believes that a particular action will achieve that end, and when it is believed that there are no co-occurring outcomes of that action whose avoidance is desired more highly than is the originally conceived end, then the actor will undertake the action which will satisfy the original desire’. An experiment is reported which examines 4-, 5, and 7-year-olds' ability to predict story characters' actions on the basis of either their true or false beliefs concerning undesirable outcomes associated with the pursuit of a desired end. Children of all age-groups provided evidence of understanding the elaborated version of belief-desire psychology. However, a significant improvement was noted between the ages of 4 and 7 years in the ability to understand circumstances involving false beliefs.     

Pulling together: building a community debriefing team.

1. Research shows that many emergency workers are affected physically and emotionally by critical incident stress. 2. Debriefings conducted by trained team members are an effective method to mitigate the impact of critical incident stress. A debriefing is a structured, time-limited group intervention. 3. Cooperation among community agencies is essential for the development and effective functioning of a critical incident stress debriefing team. 4. Several teams in Illinois have organized to form a Critical Incident Stress Debriefing Network. The Illinois network is part of an international organization composed of critical incident stress debriefing providers.