Context of First Same‐Sex Condom Use and Nonuse in Young Black Gay and Bisexual Males

Despite high human immunodeficiency virus (HIV) rates among young Black men who have sex with men (YBMSM), there are limited data about condom use during first same‐sex (FSS). This study sought to understand socio‐contextual factors of 50 YBMSM aged 15–19 years that influenced condom use during FSS. Condom use was influenced by individual, partner, and community factors. Individual factors—recent illness or sexually transmitted infections (STI)—prompted condom use, while frequent HIV testing prompted nonuse. Partner factors—proactive encouragement from partners—prompted condom use, while trust and condom discomfort prompted nonuse. Larger community factors—such as presence of females—were key for use, while limited sexual health information combined with peers who discouraged condoms prompted nonuse. A multilevel approach may be useful in developing sexual health programming for these young men.     

A clustering method for global optimization based on thekth nearest neighbour

In this paper we describe a stochastic method for global optimization based on a uniform sampling in the search domain. After a reduction of the sample, computing the distance between the remaining points and using the distribution of the kth nearest neighbour enables clusters of points to be built up, hopefully fitting the regions of attraction of significant local optima; from each of these a local search is started. The properties of the method are analysed, and detailed computational results on standard test functions are provided.     

Is it the Brazilian Way? Extending the Comparison of Public and Private Organizations

This study investigates the differences in select organizational characteristics, managerial practices and work attitudes among 670 public and private sector workers in Brazil. The results indicate that in some aspects there is a moderation effect by type of organization. For example,when public employees score high on autonomy and task significance, perceive organizational practices as favourable, and keep membership in the same organization, they tend to be more satisfied than private sector workers. Overall, the findings highlight the need for more international comparisons to gain a better understanding of the public-private distinction.     

JEEA‐FBBVA LECTURE 2013: THE NEW EMPIRICAL ECONOMICS OF MANAGEMENT

Over the last decade the World Management Survey (WMS) has collected firm‐level management practices data across multiple sectors and countries. We developed the survey to try to explain the large and persistent total factor productivity (TFP) differences across firms and countries. This review paper discusses what has been learned empirically and theoretically from the WMS and other recent work on management practices. Our preliminary results suggest that about a quarter of cross‐country and within‐country TFP gaps can be accounted for by management practices. Management seems to matter both qualitatively and quantitatively for performance at the level of the firm and the nation. Competition, governance, human capital, and informational frictions help account for the variation in management. We make some suggestions for both policy and future research.     

Special cases of the quadratic shortest path problem

The quadratic shortest path problem (QSPP) is the problem of finding a path with prespecified start vertex s and end vertex t in a digraph such that the sum of weights of arcs and the sum of interaction costs over all pairs of arcs on the path is minimized. We first consider a variant of the QSPP known as the adjacent QSPP. It was recently proven that the adjacent QSPP on cyclic digraphs cannot be approximated unless \(\hbox {P}=\hbox {NP}\). Here, we give a simple proof for the same result. We also show that if the quadratic cost matrix is a symmetric weak sum matrix and all s–t paths have the same length, then an optimal solution for the QSPP can be obtained by solving the corresponding instance of the shortest path problem. Similarly, it is shown that the QSPP with a symmetric product cost matrix is solvable in polynomial time. Further, we provide sufficient and necessary conditions for a QSPP instance on a complete symmetric digraph with four vertices to be linearizable. We also characterize linearizable QSPP instances on complete symmetric digraphs with more than four vertices. Finally, we derive an algorithm that examines whether a QSPP instance on the directed grid graph \(G_{pq}\) (\(p,q\ge 2\)) is linearizable. The complexity of this algorithm is \({\mathcal {O}(p^{3}q^{2}+p^{2}q^{3})}\).     

Fear of childbirth in primiparous Italian pregnant women: The role of anxiety,depression, and couple adjustment

Background

The prevalence of fear of childbirth in pregnant women is described to be about 20–25%, while 6–10% of expectant mothers report a severe fear that impairs their daily activities as well as their ability to cope with labour and childbirth. Research on fear of childbirth risk factors has produced heterogeneous results while being mostly done with expectant mothers from northern Europe, northern America, and Australia.