Black South African youth are disproportionately affected by the HIV epidemic, and risky sexual behaviors increase youths’ vulnerability to HIV infection. U.S.-based research has highlighted several contextual factors that impact sexual risk, but these processes have not been examined in a South African context. In a sample of Black South African parent-youth dyads, this study examined relations among parenting, neighborhood quality, maternal social support, coparenting, and youth sexual risk. Hypotheses were evaluated using structural equation modeling. Results revealed that better neighborhood quality predicted less youth sexual risk via higher levels of positive parenting. Social support was positively related to parenting quality but did not interact with neighborhood quality to impact parenting. Coparenting did not moderate the relation between parenting and sexual risk. Results highlight the importance of family- and community-level processes for youth sexual risk in an understudied and high-risk sample. HIV prevention-interventions should be informed by these contextual factors.

Studies have found that the level of association between an area-level covariate and an outcome can vary depending on the spatial scale (SS) of a particular covariate. However, covariates used in regression models are customarily modeled at the same spatial unit. In this dissertation, we developed four SS model selection algorithms that select the best spatial scale for each area-level covariate. The SS forward stepwise, SS incremental forward stagewise, SS least angle regression (LARS), and SS lasso algorithms allow for the selection of different area-level covariates at different spatial scales, while constraining each covariate to enter at most one spatial scale. We applied our methods to two real applications with area-level covariates available at multiple scales to model variation in the following outcomes: 1) nitrate concentrations in private wells in Iowa and 2) body mass index z-scores of pediatric patients of the Virginia Commonwealth University Medical Center. In both applications, our SS algorithms selected covariates at different spatial scales, producing a better goodness of fit in comparison to traditional models, where all area-level covariates were modeled at the same scale. We evaluated our methods using simulation studies to examine the performance of the SS algorithms and found that the SS algorithms generally outperformed the conventional modeling approaches. These findings underscore the importance of considering spatial scale when performing model selection.

The purpose of this thesis is to provide leaders with a clear explanation of commercial corridor revitalization, standard for evaluation, and justification for the support of existing and future commercial corridor revitalization districts in New Orleans, LA. This thesis begins with a definition of commercial corridor revitalization and discussion of how it has been applied in New Orleans, LA. A standard framework for commercial corridor revitalization development and assessment is also established with several steps for implementation included. To test the feasibility, significance and relevance of the proposed framework, all of the steps mentioned were implemented in the New Orleans East Town Center Case Study. Key findings of this research may contribute to the providing a tool that evaluates criteria for evaluating city-wide policies to support the sustainability and vitality of existing and future commercial corridor revitalization districts in New Orleans, LA.

New Orleans experienced elevated homicide rates throughout the 30 years between 1985 and 2015. The city’s homicides were especially prominent in socioeconomically disadvantaged communities. This study explored the lived experiences of residents from one such neighborhood, Hollygrove. Using qualitative methods of individual interviews, focus groups, and participant observation, the study explored homicide through three prominent theoretical lenses, Social Disorganization Theory, Subcultural theories, and Institutional Anomie Theory, to better understand the conditions in a high-homicide neighborhood that help to explain neighborhood-level violence. While existing theories of homicide causation have taken a predominately quantitative approach that compare high-homicide neighborhoods, I took an ethnographic approach informed by a social constructivist paradigm to test existing theories against the lived experiences of those whose daily lives were impacted by neighborhood-level homicide in a single community. Interviews were conducted with neighborhood residents, community leaders, neighborhood politicians, and police officials. The data indicated three conditions connected to high- or low-homicide risk in the community. The neighborhood’s values-orientation moved between subcultural values and prosocial values. Structural conditions in the community shifted between marginalization and enhanced social capital. Finally, neighborhood boundaries were found to vacillate between porous and rigidly defensive. Each of these conditions impacted the neighborhood’s ability to enact collective efficacy and to create a milieu that either resisted or enhanced the likelihood of homicide. While none of the existing theories was sufficient to explain neighborhood homicide, elements of each were present in the data.

Thesis advisor: David T. Takeuchi / Thesis advisor: Graciela Teruel-Belismelis / Poverty and violence within cities frequently concentrate in the same places and evidence suggests these exposures have deleterious consequences on health. The 2007 homicide increase in both rich and poor Mexican municipalities and the available biomarkers in a public panel study offer a unique opportunity to test each contextual effect in isolation on an innovative health outcome. Using an ecological framework, the main hypothesis of the dissertation is that, in urban environments, exposure to higher levels of contextual violence works as a stressor that wears down the body by increasing the levels of cardiovascular risk. This effect was hypothesized to be independent from poverty but with significant interactions and with heterogeneous effects among subpopulations. Multilevel cross-sectional and longitudinal analyses were conducted treating the data as a natural experiment using the homicide rate increase as treatment. The outcomes were two indices and single biomarkers that reflect cardiovascular risk in three waves of data corresponding to the years 2002, 2006, and 2012. Results showed that three complementary statistical approaches provided evidence indicating that exposure to cumulative violence at the municipality level yielded higher cardiovascular risk when controlling for individual covariates like victimization and household expenditure. The significant threshold for homicide rates was 35 and the differences between exposed and unexposed municipalities was between 1.5% & 8.3%, while the threshold for changes in the homicide rates between 2006 and 2012 was 10, with an effect size of 7%. Poverty and violence were not correlated in Mexico during the homicide rate spike, so the effects were independent. Unexpectedly, they did not show interaction effects: affluent and violent municipalities were the most stressful contexts. These effects were higher in women, in individuals in the two lowest socioeconomic quintiles and had significant impact in cohorts younger than 40 years old. The dissertation expands the ecosocial approach by exploring independent effects that shape multiple stressful contexts. It demonstrates that violence is a public health concern in Mexico that has indirect effects in the whole population, which not only worsens the obesity epidemic, but also demands a new perspective on assessing the burden of violence on everyday life. / Thesis (PhD) — Boston College, 2017. / Submitted to: Boston College. Graduate School of Social Work. / Discipline: Social Work.

Thesis (M.S.)--Boston University

Orientador: Daniela Renata Cantane / Resumo: Originadas na década de 1970, as Infecções Hospitalares vêm cada vez mais tomando proporções colossais, acarretando óbito em cerca de 30% dos pacientes em Unidades de Terapia Intensiva (UTI). Os pacientes diagnosticados com a infecções permanecem muito tempo internados, gerando um custo muito alto para os hospitais. No ambiente hospitalar a bactéria Acinetobacter baumannii a principal responsável por tais infecções, devido a sua facilidade de sobreviver em ambientes secos e úmidos, podendo sobreviver tanto no organismo humano, quanto nos ambientes que os profissionais da saúde entram em contato (computadores, equipamentos médicos, etc). Os principais vetores desta bactéria são os próprios agentes de saúde, visto que os pacientes na UTI estão todos acamados. No entanto, medidas de higienização extremamente necessárias para conter surtos da infecções o. Por outro lado, devido as emergências nestas unidades, muitas vezes não há tempo hábil para tais procedimentos. Visto que impossível uma medida total de higienização e uma taxa nula de contato da equipe de trabalho com o ambiente em UTIs, importante conhecer quais são as mínimas medidas necessárias para a diminuição de infecções hospitalares. Neste contexto, o objetivo deste trabalho propor e analisar um modelo que descreva a dinâmica de transmissão da infecção dentro de uma UTI, considerando pacientes e profissionais da saúde, assim como, propor um modelo de otimização visando determinar quais as mínimas medidas de higienização... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Originated in the 1970s, Hospital Infections come every time more taking colossal proportions, causing death in about 30% of patients in Intensive Care Units (ICU). Patients diagnosed with infections remain long hospitalized, generating a very high cost for hospitals. In the hospital environment, Acinetobacter baumannii is the main responsible for such infections due to their ease of survival in dry and humid, and can survive both in the human body and in the environments that health workers contact (computers, medical equipment, etc.). The main vectors of this bacterium are the health agents themselves, since the patients in the ICU are all bedridden. However, hygiene measures are extremely necessary to contain outbreaks of infection. On the other hand, due to emergencies in these units, there is often no time for such procedures. Since a total sanitation measure and it is important to know the minimum measures necessary for the decrease of infections. In this context, the objective xiii of this work is to propose and analyze a model that describes the dynamics of transmission of infection within an ICU, considering patients and health professionals, as well as to propose an optimization model aiming to determine the minimum hygienic measures are needed to minimize the number of infected patients. A Variable Neighborhood Search Metaheuristic was proposed to solve the optimization model. For validation of the models were carried out computational simulations. These simulation... (Complete abstract click electronic access below) / Mestre

Although the rates of delinquent behavior have been decreasing since the 1990s, adolescent delinquent behavior continues to take a great toll on society as well as on perpetrators themselves. In this way, it is essential to understand the process of delinquency development. The current dissertation is comprised of three studies that analyzed the predictors and the development of delinquency using genetically-informed designs. The sample used for all studies comes from the Add Health dataset, a nationally-representative data on adolescents followed across 14 years. The first study modeled the longitudinal development of delinquency in three adolescent cohorts: early, middle, and late adolescence. The results showed significant heritability effects on delinquency, with varying estimates across cohorts. The longitudinal stability of delinquency was mostly driven by heritability, while changes were affected by nonshared environmental influences. The second study tested the GxE interaction between two dopaminergic polymorphisms (DRD4 7-repeat allele and DRD2 A1 allele) and parenting, operationalized by child abuse on the one negative extreme and maternal closeness on the other, in longitudinally predicting delinquent behaviors. Main effects of maternal closeness and childhood abuse on later delinquency were found. On the other hand, no significant interaction of DRD2 or DRD4 polymorphisms with either maternal closeness or childhood abuse were observed. The third study used a twin design to test whether neighborhood disadvantage has a genetic component and whether this might be explained by an individual’s IQ and self-control. The results showed substantial heritability of the neighborhoods the individuals moved into as adults. This was partly explained by IQ, as adolescents’ IQ predicted neighborhood disadvantage 14 years later.

Verbal communication relies heavily on the ability to effortlessly produce intended words to express a meaning. This capacity is frequently impaired in individuals with aphasia, and impairment often lasts well into the chronic stages. However, the nature of anomia can vary. Phonological neighborhood density (PND) is one feature of words which has been shown to impact the ease of retrieval in speakers with aphasia; words with more similar-sounding neighbors are easier to retrieve because the neighbors help activate the target. However, it is unclear how different types of lexical access breakdowns affect the impact of PND. The aim of this project was to analyze the relationship between word retrieval accuracy, speech error patterns, and PND in individuals with aphasia. Twenty-two participants with various types and severities of aphasia named 200 single-syllable line drawings. WebFit, an online software program designed to fit naming data to a theoretical model of word retrieval, was used to characterize participants' error patterns by calculating the strength of connections within the lexicon, as well as the rate of decay. Analyses confirmed previous findings that participants with all types of breakdown achieved lower rates of overall accuracy. Weaker connections between semantic knowledge and words resulted in a more errors that were close to the target, relative to errors with no relationship to the target. Individuals with more severe impairments of the semantic-lexical connections and the lexical-phonological connections produced words with many neighbors more accurately than words with fewer neighbors. Implications for initial therapy target selection and directions for further research are discussed.

The Weapon Target Assignment (WTA) problem is a fundamental problem arising in defense-related applications of operations research. This problem consists of optimally assigning n weapons to m targets so that the total expected survival value of the targets after all the engagements is minimum. The WTA problem can be formulated as a nonlinear integer programming problem and is known to be NP-complete. There do not exist any exact methods for the WTA problem which can solve even small size problems (for example, with 20 weapons and 20 targets). Though several heuristic methods have been proposed to solve the WTA problem, due to the absence of exact methods, no estimates are available on the quality of solutions produced by such heuristics. In this paper, we suggest linear programming, integer programming, and network flow based lower bounding methods using which we obtain several branch and bound algorithms for the WTA problem. We also propose a network flow based construction heuristic and a very large-scale neighborhood (VLSN) search algorithm. We present computational results of our algorithms which indicate that we can solve moderately large size instances (up to 80 weapons and 80 targets) of the WTA problem optimally and obtain almost optimal solutions of fairly large instances (up to 200 weapons and 200 targets) within a few seconds