VARIATIONAL PROBLEMS INVOLVING NON-LOCAL ELLIPTIC OPERATORS

My thesis deals with nonlinear elliptic problems involving a non-local integrodifferential operator of fractional type. Our main results concern the existence of weak solutions for these problems and they are obtained using variational and topological methods

The Relative Health Burden of Selected Social and Behavioral Risk Factors in the United States: Implications for Policy

Objectives. We sought to quantify the potential health impact of selected medical and nonmedical policy changes within the United States. Methods. Using data from the 1997–2000 National Health Interview Surveys (linked to mortality data through 2002) and the 1996–2002 Medical Expenditure Panel Surveys, we calculated age-specific health-related quality-of-life scores and mortality probabilities for 8 social and behavioral risk factors. We then used Markov models to estimate the quality-adjusted life years lost. Results. Ranked quality-adjusted life years lost were income less than 200% of the poverty line versus 200% or greater (464 million; 95% confidence interval [CI] = 368, 564); current-smoker versus never-smoker (329 million; 95% CI = 226, 382); body mass index 30 or higher versus 20 to less than 25 (205 million; 95% CI = 159, 269); non-Hispanic Black versus non-Hispanic White (120 million; 95% CI = 83, 163); and less than 12 years of school relative to 12 or more (74 million; 95% CI = 52, 101). Binge drinking, overweight, and health insurance have relatively less influence on population health. Conclusions. Poverty, smoking, and high-school dropouts impose the greatest burden of disease in the United States

Mixed local-nonlocal quasilinear problems with critical nonlinearities

We study existence and multiplicity of nontrivial solutions of the following problem \left\{ \begin{array}{rcll} -\Delta_p u+(-\Delta_p)^{s} u & = & \lambda|u|^{q-2}u+|u|^{p^{\ast}-2}u & \mbox{ in }\Omega,\\ u & = & 0 & \mbox{ on } \mathbb{R}^{N} \setminus \Omega, \end{array} \right. where $\Omega\subset \mathbb{R}^N$ is a bounded open set with smooth boundary, dimension $N\geq 2$, parameter $\lambda>0$, exponents $0<s<1<p<N$, while $q\in(1,p^{\ast})$ with $p^{\ast}=\frac{Np}{N-p}$. The problem is driven by an operator of mixed order obtained by the sum of the classical $p$-Laplacian and of the fractional $p$-Laplacian. We analyze three different scenarios depending on exponent $q$. For this, we combine variational methods with some topological techniques, such as the Krasnoselskii genus and the Lusternik-Schnirelman category theories

Measurement confounding affects the extent to which verbal IQ explains social gradients in mortality

Background IQ is thought to explain social gradients in mortality. IQ scores are based roughly equally on Verbal IQ (VIQ) and Performance IQ tests. VIQ tests, however, are suspected to confound true verbal ability with socioeconomic status (SES), raising the possibility that associations between SES and IQ scores might be overestimated. We examined, first, whether two of the most common types of VIQ tests exhibited differential item functioning (DIF) favouring persons of higher SES and/or majority race/ethnicity. Second, we assessed what impact, if any, this had on estimates of the extent to which VIQ explains social gradients in mortality. Methods Data from the General Social Survey-National Death Index cohort, a US population representative dataset, was used. Item response theory models queried social-factor DIF on the Thorndike Verbal Intelligence Scale and Wechsler Adult Intelligence Scales, Revised Similarities test. Cox models examined mortality associations among SES and VIQ scores corrected and uncorrected for DIF. Results When uncorrected for DIF, VIQ was correlated with income, education, occupational prestige and race, with correlation coefficients ranging between |0.12| and |0.43|. After correcting for DIF, correlations ranged from |0.06| to |0.16|. Uncorrected VIQ scores explained 11–40% of the Relative Index of Inequalities in mortality for social factors, while DIF-corrected scores explained 2–29%. Conclusions Two of the common forms of VIQ tests appear confound verbal intelligence with SES. Since these tests appear in most IQ batteries, circumspection may be warranted in estimating the amount of social inequalities in mortality attributable to IQ

A community perspective on the role of fathers during pregnancy: a qualitative study

BACKGROUND: Defining male involvement during pregnancy is essential for the development of future research and appropriate interventions to optimize services aiming to improve birth outcomes. Study Aim: To define male involvement during pregnancy and obtain community-based recommendations for interventions to improve male involvement during pregnancy. METHODS: We conducted focus groups with mothers and fathers from the National Healthy Start Association program in order to obtain detailed descriptions of male involvement activities, benefits, barriers, and proposed solutions for increasing male involvement during pregnancy. The majority of participants were African American parents. RESULTS: The involved “male” was identified as either the biological father, or, the current male partner of the pregnant woman. Both men and women described the ideal, involved father or male partner as present, accessible, available, understanding, willing to learn about the pregnancy process and eager to provide emotional, physical and financial support to the woman carrying the child. Women emphasized a sense of “togetherness” during the pregnancy. Suggestions included creating male-targeted prenatal programs, enhancing current interventions targeting females, and increasing healthcare providers’ awareness of the importance of men’s involvement during pregnancy. CONCLUSIONS: Individual, family, community, societal and policy factors play a role in barring or diminishing the involvement of fathers during pregnancy. Future research and interventions should target these factors and their interaction in order to increase fathers’ involvement and thereby improve pregnancy outcomes

Intraocular pressure and medication changes associated with Xen gel stent: A systematic review of the literature

The Xen gel stent (Allergan Inc, an AbbVie company; Dublin, Ireland) was conceived as an option for patients requiring modest IOP reduction but for whom trabeculectomy was not yet indicated. As with any glaucoma surgery, establishing criteria for patient selection and identifying factors that contribute to a high likelihood of success are important. To help guide clinical decision-making, a systematic review of published studies on the gel stent was performed, with the goal of understanding postoperative outcomes based on clinical and patient factors. Results were organized around a series of pertinent clinical questions based on scenarios encountered in clinical practice. Criteria for including studies were intentionally broad, with the objective of simulating the diverse population of glaucoma patients encountered in real-world practice. Outcomes for IOP and medication reduction postoperatively were assessed in various analyses, including in eyes with various glaucoma types and severity; in eyes naïve to surgery as well as those with a history of prior incisional glaucoma surgery; and when surgery was performed as a standalone procedure or at the time of cataract surgery. The results of each of the various analyses were consistent in demonstrating that successful gel stent surgery achieved a postoperative IOP of approximately 14.0 mm Hg and reduction to fewer than 1 glaucoma medication. Additional data are shown on outcomes by method of implant (ab interno vs ab externo); intraoperative use of antifibrotics; and rates of needling in published studies

Do changes in traditional coronary heart disease risk factors over time explain the association between socio-economic status and coronary heart disease?

<p>Abstract</p> <p>Background</p> <p>Socioeconomic status (SES) predicts coronary heart disease independently of the traditional risk factors included in the Framingham risk score. However, it is unknown whether <it>changes </it>in Framingham risk score variables over time explain the association between SES and coronary heart disease. We examined this question given its relevance to risk assessment in clinical decision making.</p> <p>Methods</p> <p>The Atherosclerosis Risk in Communities study data (initiated in 1987 with 10-years follow-up of 15,495 adults aged 45-64 years in four Southern and Mid-Western communities) were used. SES was assessed at baseline, dichotomized as low SES (defined as low education and/or low income) or not. The time dependent variables - smoking, total and high density lipoprotein cholesterol, systolic blood pressure and use of blood pressure lowering medication - were assessed every three years. Ten-year incidence of coronary heart disease was based on EKG and cardiac enzyme criteria, or adjudicated death certificate data. Cox survival analyses examined the contribution of SES to heart disease risk independent of baseline Framingham risk score, without and with further adjustment for the time dependent variables.</p> <p>Results</p> <p>Adjusting for baseline Framingham risk score, low SES was associated with an increased coronary heart disease risk (hazard ratio [HR] = 1.53; 95% Confidence Interval [CI], 1.27 to1.85). After further adjustment for the time dependent variables, the SES effect remained significant (HR = 1.44; 95% CI, 1.19 to1.74).</p> <p>Conclusion</p> <p>Using Framingham Risk Score alone under estimated the coronary heart disease risk in low SES persons. This bias was not eliminated by subsequent changes in Framingham risk score variables.</p