Local search algorithms for multiple-depot vehicle routing and for multiple traveling salesman problems with proved performance guarantees

We consider two related problems: the multiple-depot vehicle routing problem (MDVRP) and the Multiple traveling salesman problem (mTSP). In both of them, given is the complete graph on n vertices \(G = (V,E)\) with nonnegative edge lengths that form a metric on V. Also given is a positive integer k. In typical applications, V represents locations of customers and k represents the number of available vehicles. In MDVPR, we are also given a set of k depots \(\{O_1,\ldots ,O_k\} \subseteq V\) , and the goal is to find a minimum-length cycle cover of G of size k, that is, a collection of k (possibly empty) cycles such that each \(v \in V\) is in exactly one cycle, and each cycle in the cover contains exactly one depot. In mTSP, no depots are given, so the goal is to find (any) minimum-length cycle cover of G of size k. We present local search algorithms for both problems, and we prove that their approximation ratio is 2.     

Selfish bin coloring

The bin packing problem, a classical problem in combinatorial optimization, has recently been studied from the viewpoint of algorithmic game theory. In this bin packing game each item is controlled by a selfish player minimizing its personal cost, which in this context is defined as the relative contribution of the size of the item to the total load in the bin.     

Can Relaxation of Beliefs Rationalize the Winner's Curse?: An Experimental Study

We use a second‐price common‐value auction, called the maximal game, to experimentally study whether the winner's curse (WC) can be explained by models which retain best‐response behavior but allow for inconsistent beliefs. We compare behavior in a regular version of the maximal game, where the WC can be explained by inconsistent beliefs, to behavior in versions where such explanations are less plausible. We find little evidence of differences in behavior. Overall, our study casts a serious doubt on theories that posit the WC is driven by beliefs.     

The relationship between organizational factors and resident satisfaction with nursing home care and life

We examined the relationships between nursing home (NH) resident satisfaction and NH organizational characteristics, while controlling for the effect of resident characteristics within facilities. We used a stratified, random sample of NHs (N = 72) from two states and a prescreened and randomized sample of 1496 residents. Data sources included resident interviews, an administrator survey, the Minimum Data Set (MDS), and the Online Survey, Certification and Reporting System (OSCAR). Using Hierarchical Linear Modeling (HLM) techniques, we found that non-chain affiliation, certified nursing assistant staffing, and provision of a family council had significant positive effects on total resident satisfaction. The presence of a special care unit was associated with lower levels of satisfaction.     

Nonstandard Work and Marital Instability: Evidence From the National Longitudinal Survey of Youth

This article replicated and extended Harriet Presser's (2000) investigation of the linkages between nonstandard work and marital instability. We reexplored this question using data from a sample of 2,893 newlywed couples from the National Longitudinal Survey of Youth (NLSY) and using different analytic techniques. In contrast to Presser, we found that the key dimension of husbands' and wives' employment was nonemployment. Similar to Presser, we found that wives' working of fixed night shifts increased the risk of divorce, driven by the experience in marriages over 5 years in duration. However, we did not replicate Presser's finding that the effect is significant only among households with children; rather, wives' fixed night shifts were associated with divorce only among those without children.     

The beneficial effects of different types of exercise interventions on motor and cognitive functions in older age: a systematic review

The decline in cognitive and motor functions with age affects the performance of the aging healthy population in many daily life activities. Physical activity appears to mitigate this decline or even improve motor and cognitive abilities in older adults. The current systematic review will focus mainly on behavioral studies that look into the dual effects of different types of physical training (e.g., balance training, aerobic training, strength training, group sports, etc.) on cognitive and motor tasks in older adults with no known cognitive or motor disabilities or disease. Our search retrieved a total of 1095 likely relevant articles, of which 41 were considered for full-text reading and 19 were included in the review after the full-text reading. Overall, observations from the 19 included studies conclude that improvements on both motor and cognitive functions were found, mainly in interventions that adopt physical-cognitive training or combined exercise training. While this finding advocates the use of multimodal exercise training paradigms or interventions to improve cognitive-motor abilities in older adults, the sizeable inconsistency among training protocols and endpoint measures complicates the generalization of this finding.     

Couple Forgiveness and its Moderating Role in the Intergenerational Transmission of Veterans’ Posttraumatic Stress Symptoms

This study examined the moderating effect couple forgiveness (as perceived by the wives/mothers) may have on the intergenerational transmission of posttraumatic stress symptoms (PTSS) among families of combat veterans and former prisoners of war (ex‐POWs). The sample included 123 (79 ex‐POWs and 44 control combatants) Israeli father–mother–adult offspring triads. Self‐report measures were administered at 2008 to veterans, at 2010–2011 to wives, and at 2013–2014 to offspring. The findings indicated that ex‐POWs’ PTSS were positively related to their offspring's PTSS, while couple forgiveness buffered this effect, particularly, and detrimentally, when couple forgiveness was low. These findings imply that apprehending the quality of the forgiving atmosphere within the marital relationship may be important for understanding the apparatus of intergenerational transmissions of trauma.     

Self-Care—New Challenge to Individual Health

Abstract

We are beginning to recognize that further improvements in health care are best achieved through the development of the lay resource in health in contrast to the professional resource. Recent research has shown that the vast proportion of health care still remains in the hands of lay people, and that efforts aimed at improving this resource can have a powerful effect on health and the health care industry. It is important now that health professionals recognize a new public interest in demystifying medicine and deprofessionalizing health care.

With this increased recognition we can begin the road back to establishing a health competent society, less dependent on unnecessary professional intrusion. We can also look forward to a broader-based perspective on health and health care, which may very well involve new concepts of health that are at variance with present professional views and practices. We can also expect to achieve a new level of equity in responsibility for the production of health care as well as its consumption.     

Seasonality of Sexual Debut

This study brings together insights from two bodies of scholarship that have heretofore existed as parallel research literatures, namely, research on the social antecedents of sexual debut and scholarship on the seasonality of coital activity. The authors use the National Longitudinal Study of Adolescent Health to discover two seasonal peaks in the reported onset of first intercourse, one in the early summertime months for adolescents in general (the summer effect) and another during December for romantically involved adolescents (the holiday season effect). The authors explore the social contours of these patterns by analyzing the effects of gender, race, and partner relationship context (romantic vs. nonromantic) on each peak. Summertime debuts typically occur between nonromantic partners, and wintertime debuts typically occur between romantic partners.     

Will It Help? Identifying Socialization Discourses That Promote Sexual Risk and Sexual Health Among African American Youth

Because much of the existing research examining sexual communication to African American youth focuses on demographic and parental factors predicting sexual risk behaviors, less is known about factors predicting sexual health, and little is understood about the contributions of peer communications. The current study aimed to expand existing approaches by assessing which socialization discourses communicated by parents and peers contribute to sexual risk and health outcomes (sexual assertiveness, positive sexual affect, and condom self-efficacy). Participants were 631 African American undergraduates (73% female) who indicated the extent to which they had received from their parents and peers each of 28 messages representing four cultural discourses: abstinence, relational sex, sex positive, and gendered sexual roles. As expected, parents were perceived to emphasize relational sex and abstinence messages more than peers, and peers were perceived to communicate sex-positive and gendered sex role messages more than parents. Greater exposure to abstinence messages predicted lower levels of sexual experimentation, whereas exposure to sex-positive messages predicted higher levels. In addition, exposure to relational sex and sex-positive messages predicted higher levels of sexual assertiveness and positive sexual affect. Implications are discussed concerning sexual communications that could help Black youth develop healthy sexual perspectives.