Improved Approximation for Breakpoint Graph Decomposition and Sorting by Reversals

Sorting by Reversals (SBR) is one of the most widely studied models of genome rearrangements in computational molecular biology. At present, is the best known approximation ratio achievable in polynomial time for SBR. A very closely related problem, called Breakpoint Graph Decomposition (BGD), calls for a largest collection of edge disjoint cycles in a suitably-defined graph. It has been shown that for almost all instances SBR is equivalent to BGD, in the sense that any solution of the latter corresponds to a solution of the former having the same value. In this paper, we show how to improve the approximation ratio achievable in polynomial time for BGD, from the previously known to for any > 0. Combined with the results in (Caprara, Journal of Combinatorial Optimization, vol. 3, pp. 149–182, 1999b), this yields the same approximation guarantee for n! – O((n – 5)!) out of the n! instances of SBR on permutations with n elements. Our result uses the best known approximation algorithms for Stable Set on graphs with maximum degree 4 as well as for Set Packing where the maximum size of a set is 6. Any improvement in the ratio achieved by these approximation algorithms will yield an automatic improvement of our result.     

Environmental and socioeconomic determinants of neonatal mortality in a northern Italian city in the early nineteenth century

Population and Environment - The research explores the effects of the environment on neonatal mortality in the early nineteenth century, controlling for social and economic factors. Individual...     

Divorce Chinese Style

This study investigated divorce during China's social and economic transformation period from 1970 to 2012. Specifically, the study examined the trend development of divorce and demonstrated how marriage formation type and individual socioeconomic characteristics were associated with the likelihood of divorce across time. Event‐history analysis was applied to longitudinal data from the China Family Panel Studies (2010–2012 waves). The results showed a threefold increase in divorce from the pre‐1990s to the 1990s. Surprisingly, the trend shifted to a plateau toward the 2000s. When cohabitation was in its rapidly diffusing stage in the 1990s, individuals who cohabited prior to marriage had a substantially higher likelihood of divorce. As cohabitation became increasingly common in the 2000s, its effect on divorce weakened. The role of socioeconomic characteristics in divorce also varied across time. This study enriches the knowledge of family dynamics in contemporary Chinese society.     

Model selection in high-dimensional noisy data: a simulation study

In many practical applications, high-dimensional regression analyses have to take into account measurement error in the covariates. It is thus necessary to extend regularization methods, that can handle the situation where the number of covariates p largely exceed the sample size n, to the case in which covariates are also mismeasured. A variety of methods are available in this context, but many of them rely on knowledge about the measurement error and the structure of its covariance matrix. In this paper, we set the goal to compare some of these methods, focusing on situations relevant for practical applications. In particular, we will evaluate these methods in setups in which the measurement error distribution and dependence structure are not known and have to be estimated from data. Our focus is on variable selection, and the evaluation is based on extensive simulations.     

Incorporating human sexuality content into a positive youth development framework: Implications for community prevention

As approaches to positive youth development (PYD) gain momentum, the issue of sexuality – a critical component of human development – is being subsumed by ideological debates. In the current political climate, sexuality education is often relegated to biological and/or values-based approaches, neglecting essential relational and collective aspects of sexuality. Through the explication of sexuality as an important component of youth's social ecology, this paper provides a conceptual link between the goals of the Sexuality Information and Education Council of the United States' (SIECUS) Guidelines for comprehensive sexuality education and those of PYD. We argue that sexuality, as a normative part of human development, culture, identity, and relationships, be approached from an asset-based perspective, rather than a deficit-based perspective. We propose a framework that illustrates how aspects of sexuality are embedded within PYD contexts, and demonstrates how a sexuality education program rooted in SIECUS guidelines can further PYD goals across community contexts.     

Summer temperature effects on deaths and hospital admissions among the elderly population in two Italian cities

In developed countries the effects of climate on health status are mainly due to temperature. Our analysis is aimed to deepen statistically the relationship between summer climate conditions and daily frequency of health episodes: deaths or hospital admissions. We expect to find a U-shaped relationship between temperature and frequencies of events occurring in summer regarding the elderly population resident in Milano and Brescia. We use as covariates hourly records of temperature recorded at observation sites located in Milano and Brescia. The analysis is performed using Generalized Additive Models (GAM), where the response variable is the daily number of events, which varies as a possibly non-linear function of meteorological variables measured on the same or previous day. We consider separate models for Milano and Brescia and then we compare temperature effects among the two towns and among different age classes. Moreover we consider separate models for all diagnosed events, for those due to respiratory disease and those due to circulatory pathologies. Model selection is a central problem, the basic methods used are the UBRE and GCV criteria but, instead of conditioning all final conclusions on the best model according to the chosen criterion, we investigated the effect of model selection by implementing a bootstrap procedure.     

Psychosocial contexts of the homosexuality of Filipino men in heterosexual unions

The Philippines is one developing country in which a systematic inquiry on the homosexuality of men in heterosexual consensual union is rare. With the thought that the public can be guided more knowledgeably in forming some responsible knowledge and opinion about homosexual men's lives within heterosexual unions, a small-scale exploratory study was carried out and completed in 1997 among 15 married or co-habiting men in Metro Manila, the Philippines. The research delved into respondents' sexual histories; their perceptions of own homosexual attraction, desire and orientation; and their reasons, motivations and expectations for marrying or cohabiting. It also looked into respondents' reports of whether their partners knew their sexual orientation; respondents' roles and responsibilities in household management and decision making; and effects of respondents' homosexuality on marital and familial relationships.