Inapproximability results for the lateral gene transfer problem

This paper concerns the Lateral Gene Transfer Problem. This minimization problem, defined by Hallett and Lagergren (2001), is that of finding the most parsimonious lateral gene transfer scenario for a given pair of gene and species trees. Our main results are the following:

Exposure to Violence,Coping Strategies,and Diagnosed Mental Health Problems Among Adults in a Migrant-Sending Community in Central Mexico

Deadly violence has spread throughout Mexico, affecting the well-being of citizens. What is the impact of this violence on the daily lives of Mexican adults? Building upon the stress process model, we used a mixed-methods approach to examine relationships between multiple indicators of exposure to and fear of violence and four diagnosed mental health outcomes, as well as self-rated mental health, in a Mexican community using the Survey of Health and Mexican Migration (456 surveys; 49 interviews). The multivariate models provide evidence that perceptions of insecurity are associated with diagnosed depressive episode, agoraphobia, alcohol abuse, a total count of mental health conditions, and poor self-rated mental health. Past victimization is associated with anxiety. Stress and coping behaviors did not formally mediate these violence–mental illness associations. The qualitative results confirm that residents fear violence and cope by adjusting their personal behaviors. These results foreshadow the emergence of mental health conditions as a critical public health concern for Mexicans living under the threat of violence.     

Urban park area and age determine the richness of native and exotic plants in parks of a Latin American city: Santiago as a case study

Plant diversity and composition in urban parks is determined by socio-economics, environmental, and ecological drivers. These drivers give rise to urban spaces with unique compositions of flora, consisting of planted and spontaneous species. The present study aimed to determine the contribution of native and exotic species in urban parks of a Latin American city, and to assess the related role of park area, age and socio-economic status. We also evaluated administration type (public or private) and the effect of environmental factors on plant richness. We hypothesized that the composition of park vegetation differs according to urban-rural gradient. To determine flora composition, two transects (100 m long by 1–3 m wide) per park were selected in 49 parks. In each of these, we identified all the vascular plants found (woody and herbs, planted and spontaneous), which were then classified as native or exotic. We conducted ANCOVAs in order to determine the effect of five independent variables and one factor, on native and exotic plant richness. Of 550 recorded species, 16.2% were native and 83.8% exotic. Number of plant species per park varied between 42 and 146. The parks are known urban habitats containing the highest planted and spontaneously occurring exotic diversity in the city of Santiago, contrasting with other types of habitats. Likewise, parks in Santiago are habitats with low levels of planted and spontaneously occurring native diversity, compared to the parks of Europe, America North and Asia. Ours results show that park area and age affected native plant richness, while exotic plant richness was determined only by park age. We rejected all other possible drivers. Finally, according to the low frequency of native species, we propose that Santiago’s parks could be gradually reoriented towards ex-situ conservation of native plants.     

The Sonoran Desert’s Domestic Bracero Programme: Institutional Actors and the Creation of Labour Migration Streams

This paper traces the journeys of male migrants to Empalme, Sonora, Mexico to uncover the development of the often overlooked domestic bracero programme that operated in conjunction with its well‐known international equivalent. Drawing on interviews and observations with ex‐braceros who met at a park near the Mexico‐US border, I examine their experiences and participation in Mexico’s domestic bracero program, an unintended and unexplored consequence of its international counterpart. The study shows how regulation and control were constantly reinvented at every step of the selection process by state actors and their affiliates in Mexico. The paper reveals how the oversupply of labour and modernization of agriculture in Sonora resulted in the development of a migration industry where local municipal leaders, coyotes, the state, and Mexican agribusiness capitalized from men’s displacement. The migration industry during the bracero selection process controlled who gained access to the United States labour market by capturing migrant labour en route to the United States in the process fueling a thriving cotton industry in the otherwise stagnant Sonoran Desert economy. The study concludes by taking the lessons from the historic domestic bracero programme to show one instance in which internal and international labour markets were closely interwoven. In the end, I call for more research that examines the relationship between markets on both sides of the border that uncovers how networks are not only structured by personal ties but also by state and market relations.     

Conditional Inference Trees: A Method for Predicting Intimate Partner Violence

A number of different methodologies have been employed to investigate the complex relationship between psychological and physical aggression. Herein, a method of unbiased recursive partitioning (conditional inference trees) was applied to a longitudinal sample to identify cutoffs of psychological aggression at baseline that differentiate between individuals who do and do not perpetrate physical aggression at follow‐up. The algorithm categorized men into low‐ and high‐risk groups, and women into mild‐, moderate‐, or high‐risk categories of perpetration. Couples responded anonymously to a self‐report measure of psychological and physical aggression (CTS2) at baseline and a 12‐month follow‐up. Sensitivity analyses for predicting physical aggression reached as high as 59% for women and 60% for men.     

Equality of Educational Opportunities,Schools’ Characteristics and Resilient Students: An Empirical Study of EU-15 Countries Using OECD-PISA 2009 Data

In the existent literature, little attention has been paid to the characteristics of the schools attended by the “resilient” students, i.e. those that, despite their socioeconomic background, are able to obtain high academic results. The paper explores this topic by using OECD-PISA 2009 data for EU-15 countries; we estimate a statistical model to find those school-level variables that are correlated with the probability of a disadvantaged student being resilient, net of country-specific structural differences. A by-product of the study is a better understanding of the educational drivers that help disadvantaged students and this can be beneficial for a country’s educational system as a whole. In particular, the analysis reveals that schools attended by resilient students do offer more extracurricular activities and are characterized by a better positive school climate.     

Entry and Exit Strategies in Migration Dynamics

In this paper, we use a real option framework in order to study the role of combined entry and exit strategies in migration. The paper’s aim consists in investigating migrants’ behaviour and in particular their duration of stay in the host country. Our framework shows two threshold levels: the first triggers the migration choice, while the second triggers the return to the country of origin. The difference between these two thresholds defines a region of inaction (hysteresis) i.e. the length of the immigrant’s stay in the host country (duration). Our theoretical results show that: (a) the phenomenon of hysteresis is amplified by ethnic communities both in entry and in exit cases; and (b) migration policies that attempt to exacerbate entry could increase duration of immigrants and the migration stock in the host country. Furthermore, the community could reduce the minimum wage level required to trigger both exit and entry. This fact could explain why we sometimes see migration inflows with a low wage differential and also with underemployment.     

Healthy, educated and wealthy: A primer on the impact of public and private welfare expenditures on economic growth

In this paper, we provide first evidence of the impact of public and private expenditures in health and education on economic growth, via their influence on people's health, skills and knowledge. We consider a growth accounting framework in order to test whether countries that devote a larger amount of resources to the consumption of health and educational services experience higher growth rates. We also test whether the effects on economic growth of public expenditure in health and education differ from those of private expenditure. Our empirical analysis is based on a panel of 19 OECD countries observed between 1971 and 1998. The results are consistent with the hypothesis that health and education expenditure affects positively growth. The estimated impact is stronger for health than for education. More importantly, we find some evidence that public expenditure influences GDP growth more than private expenditure.