On damage accumulation and biological aging

If biological aging is understood as some process of damage accumulation, it does not necessarily lead to increasing mortality rate. Within the framework of suggested models and relevant examples we show that even for the monotonically increasing degradation, the mortality rate can, at least, ultimately decrease. Aging properties of systems with imperfect repair are also studied. It is shown that for some models of imperfect repair the corresponding age process is monotone and stable. This means that as t→∞$t\to \infty$, degradation slows down, which results in the mortality rate deceleration and its possible convergence to a constant.     

Achievement and Behavior Among Children of Welfare Recipients, Welfare Leavers, and Low-Income Single Mothers

This article examines the behavior and achievement of children infemale-headed families that were on welfare, that left welfare, and that were not on welfare in the3 years preceding the study. Data come from the Panel Study of Income Dynamics Child Development Supplement, a nationally representative sample of children under age 13 collected in 1997. The results suggest that there are both positive and negative outcomes of welfare transitions. Based upon our results, children whose mothers are able to leave and remain off welfare score consistently better on cognitive tests of their development. The transition period, however, is a difficult one. Children's emotional well-being may suffer during the parental transition from cash assistance to self-sufficiency.     

The developmental priority of the evaluative dimension in perceptions of nonverbal cues

Researchers who have attempted to map the basic structure of broad psychological domains (such as interpersonal behavior) have invariably pointed to the importance of the evaluative dimension. It was predicted that sensitivity to such a salient dimension would develop prior to sensitivity to other important but apparently weaker dimensions, such as dominance-submissiveness. The predicted developmental trend was supported in a study of nonverbal decoding. When judging pairs of emotional cues communicated by the face or body and by the tone of voice, younger subjects, compared to older ones, were more likely to notice discrepancies in the degree of expressed positivity than in the degree of expressed dominance.     

Family-centered group care

Alternate frameworks for a model of residential group care focused on the family have the primary objective of early discharge from group care. The proposals are based on an agency's experience.     

Burn-in for Eliminating Weak Items in Heterogeneous Populations

Burn-in is a method of eliminating early failures in populations of manufactured items. To burn-in a component or a system means to subject it to a ‘‘simulated operation’’ for some time (prior to its actual field use). Various optimal burn-in problems have been intensively studied in the literature under the assumption of decreasing or bathtub-shaped failure rates. However, most of these studies have been conducted for homogeneous populations. In this paper, we discuss burn-in for heterogeneous populations and develop approaches that minimize the risks of selecting items with large levels of individual failure rates. Using simple examples, we consider the optimal burn-in time, which minimizes these risks.     

Prevalence of sarcopenia and its association with functional and nutritional status among male residents in a nursing home in Turkey

Introduction The Aging Male Symptoms' (AMS) scale was designed as a health-related quality of life (QoL) scale and standardized as a self-administered scale, first, to assess symptoms of aging (independent from those which are disease-related) between groups of males under different conditions, second, to evaluate the severity of symptoms/QoL over time, and, third, to measure changes pre- and post-androgen replacement therapy. The scale is in widespread use (17 languages currently available) and a recent review of methodological data documented good psychometric characteristics and ability as a clinical utility. This paper describes test characteristics of the AMS (positive and negative predictive values), taking two internationally established and published screening scales for androgen deficiency as the available standard.

Method A sample of 150 German males aged 40–69 years completed the AMS scale and two screening scales for androgen deficiency: the ADAM scale of Morley and colleagues and the screener of Smith and colleagues. The technique of a computer-assisted telephone interview was applied.

Result The comparison of the AMS with the two screening instruments for androgen deficiency showed sufficiently good compatibility despite conceptual differences. The AMS scale sufficiently predicted the results of the two screening instruments. A positive predictive value of 92% and a negative predictive value of 50% were found regarding the ADAM scale. The respective figures regarding Smith's screener were 65% and 49% for positive and negative predictive values, respectively.

Conclusion The AMS scale obviously measures a similar phenomenon as the two established and widely used screeners for androgen deficiency, although it was not developed as a screening instrument.     

Estimation for an accelerated failure time model with intermediate states as auxiliary information

Lifetime Data Analysis - The accelerated failure time (AFT) model is a common method for estimating the effect of a covariate directly on a patient’s survival time. In some cases, death is...     

Conservative confidence intervals for a single parameter

The method of constructing confidence intervals from hypothesis tests is studied in the case in which there is a single unknown parameter and is proved to provide confidence intervals with coverage probability that is at least the nominal level. The confidence intervals obtained by the method in several different contexts are seen to compare favorably with confidence intervals obtained by traditional methods. The traditional intervals are seen to have coverage probability less than the nominal level in several instances, This method can be applied to all confidence interval problems and reduces to the traditional method when an exact pivotal statistic is known.     

A Model of Aging and a Shape of the Observed Force of Mortality

A probabilistic model of aging is considered. It is based on the assumption that a random resource, a stochastic process of aging (wear) and the corresponding anti-aging process are embedded at birth. A death occurs when the accumulated wear exceeds the initial random resource. It is assumed that the anti-aging process decreases wear in each increment. The impact of environment (lifestyle) is also taken into account. The corresponding relations for the observed and the conditional hazard rate (force of mortality) are obtained. Similar to some demographic models, the deceleration of mortality phenomenon is explained via the concept of frailty. Simple examples are considered.