Adjusting HIV Prevalence Estimates for Non-participation: an Application to Demographic Surveillance

Introduction: HIV testing is a cornerstone of efforts to combat the HIV epidemic, and testing conducted as part of surveillance provides invaluable data on the spread of infection and the effectiveness of campaigns to reduce the transmission of HIV. However, participation in HIV testing can be low, and if respondents systematically select not to be tested because they know or suspect they are HIV positive (and fear disclosure), standard approaches to deal with missing data will fail to remove selection bias. We implemented Heckman-type selection models, which can be used to adjust for missing data that are not missing at random, and established the extent of selection bias in a population-based HIV survey in an HIV hyperendemic community in rural South Africa.

Methods: We used data from a population-based HIV survey carried out in 2009 in rural KwaZulu-Natal, South Africa. In this survey, 5565 women (35%) and 2567 men (27%) provided blood for an HIV test. We accounted for missing data using interviewer identity as a selection variable which predicted consent to HIV testing but was unlikely to be independently associated with HIV status. Our approach involved using this selection variable to examine the HIV status of residents who would ordinarily refuse to test, except that they were allocated a persuasive interviewer. Our copula model allows for flexibility when modelling the dependence structure between HIV survey participation and HIV status.

Results: For women, our selection model generated an HIV prevalence estimate of 33% (95% CI 27–40) for all people eligible to consent to HIV testing in the survey. This estimate is higher than the estimate of 24% generated when only information from respondents who participated in testing is used in the analysis, and the estimate of 27% when imputation analysis is used to predict missing data on HIV status. For men, we found an HIV prevalence of 25% (95% CI 15–35) using the selection model, compared to 16% among those who participated in testing, and 18% estimated with imputation. We provide new confidence intervals that correct for the fact that the relationship between testing and HIV status is unknown and requires estimation.

Conclusions: We confirm the feasibility and value of adopting selection models to account for missing data in population-based HIV surveys and surveillance systems. Elements of survey design, such as interviewer identity, present the opportunity to adopt this approach in routine applications. Where non-participation is high, true confidence intervals are much wider than those generated by standard approaches to dealing with missing data suggest.

Approximating Credal Network Inferences by Linear Programming

An algorithm for approximate credal network updating is presented. The problem in its general formulation is a multilinear optimization task, which can be linearized by an appropriate rule for fixing all the local models apart from those of a single variable. This simple idea can be iterated and quickly leads to very accurate inferences. The approach can also be specialized to classification with credal networks based on the maximality criterion. A complexity analysis for both the problem and the algorithm is reported together with numerical experiments, which confirm the good performance of the method. While the inner approximation produced by the algorithm gives rise to a classifier which might return a subset of the optimal class set, preliminary empirical results suggest that the accuracy of the optimal class set is seldom affected by the approximate probabilities

Demographic, Physical, and Behavioral Characteristics Associated with TV Parenting Practices Among Latino Parents of Preschool Children

Thesis (Master's)--University of Washington, 2015

Bivalve taxonomic diversity throughout the Italian Pliocene as a tool for climatic-oceanographic and stratigraphic inferences

The state of research on the evolution of marine bivalve taxonomic diversity of the Mediterranean Pliocene is analysed. The following assertions are discussed: 1) The Early Pliocene malacofauna is characterized by a high number of warm-water taxa and a high taxonomic diversity with respect to that of the present time. 2) The first appreciable extinction event in the Mediterranean Pliocene approximates or just follows the FO of Globorotalia bononiensis. 3) The second appreciable extinction event is between the LAD of Discoaster tamalis and the LAD of Discoaster surculus . 4) A third minor extinction event is penecontemporaneous with the FO of Globorotalia inflaia. Taking into account the available data on the Pliocene extinction events it has been possible to distinguish 4 different molluscan units with different climatic-oceanographic significance.

Socio-demographic correlates of physical activity of European adults: A cross-sectional study from the European Social Survey

ABSTRACT - Background: From a public health perspective, the study of socio-demographic factors related to physical activity is important in order to identify subgroups for intervention programs. Purpose: This study also aimed to identify the prevalence and the socio-demographic correlates related with the achievement of recommended physical activity levels. Methods: Using data from the European Social Survey round 6, physical activity and socio-demographic characteristics were collected from 39278 European adults (18271 men, 21006 women), aged 18-64 years, from 28 countries in 2012. Meeting physical activity guidelines was assessed using World Health Organization criteria. Results: 64.50% (63.36% men, 66.49% women) attained physical activity recommended levels. The likelihood of attaining physical activity recommendations was higher in age group of 55-64 years (men: OR=1.22, p<0.05; women: OR=1.66, p<0.001), among those who had completed high school (men: OR=1.28, p<0.01; women: OR=1.26, p<0.05), among those who lived in rural areas (men: OR=1.20, p<0.001; women: OR=1.10, p<0.05), and among those who had 3 or more people living at home (men: OR=1.40, p<0.001; women: OR=1.43, p<0.001). On the other hand, attaining physical activity recommendations was negatively associated with being unemployed (men: OR=0.70, p<0.001; women: OR=0.87, p<0.05), being a student (men: OR=0.56, p<0.001; women: OR=0.64, p<0.01), being a retired person (men: OR=0.86, p<0.05) and with having a higher household income (OR=0.80, p<0.001; women: OR=0.81, p<0.01). Conclusion: This research helped clarify that, as the promotion of physical activity is critical to sustain health and prevent disease, socio-demographic factors are important to consider when planning the increase of physical activity.

A comparison of life satisfaction, job satisfaction, and happiness using demographic variables

This study examined the interrelationships among life satisfaction, job satisfaction, and happiness and the selected demographic variables of income, age, marital status, education, sex, job tenure, job title, type of school, and location of employment. Survey data were collected from 1,993 elementary, high school, and community college teachers in the southern Ontario area, representing ten public school boards, three Roman Catholic school boards and three community colleges. Several theories were utilized in developing thirteen hypotheses and eleven experimental hypotheses. A thorough review of the literature (to January, 1980) was undertaken and major conclusions noted. Hoppock's (1935) Job Satisfaction Measure, Gurin, Veroff, and Feld's (1960) Happiness Scale, and Converse and Robinson's (1965) Life Satisfaction Scale were used as the instrument. Chi-square analysis was employed as the statistical method. Indicative of the findings: the level of education taught was significantly related to all three organizational variables, sex was unrelated to life satisfaction though positively related to job satisfaction, and income was found not to be related to either happiness or life satisfaction. A minority of findings were contrary to hypothesized relationships. Specifically, age was found to be unrelated to any of the three organizational variables, and educational achievement was not significantly related to happiness. A model was developed to illustrate the interrelationships of the organizational and demographic variables. This model was designed specifically to reflect teacher attitudes, though it may have reasonable application for other relatively homogeneous groups of employees such as nurses, engineers, or social workers.

Demographic and genetic attributes of dispersing and resident individuals of an enclosed Microtus pennsylvanicus population

A dispersal polymorphism may exist in emigrants from cyclic populations of Microtus '~nnsylvanicus biasing trap-revealed movements of unenclosed animals in favour of sedentary or colonizing individuals. The dispersal tendency of emigrants from an enclosed population was investigated by releasing animals via tubes into one of two adjacent enclosures, one vacant and one inhabited. Individuals from the enclosed population were monitored for age, sex, weight and electrophoretically detectable serum transferrin genotype in an intensive live-trapping program. In 1973 the minimum number alive in the introduced enclosed study population reached approximately l67/ha when breeding stopped in October. In 1974 intensive breeding increased the population density to 333/ha by mid-July when a long decline in numbers and breeding intensity began without an intervening plateau. An adjacent unenclosed area had a much lower density and longer breeding season in 1974. The growth rate of young males in the enclosed population tended to be lowest during the decline period in 1974. Survival of the enclosed population was high throughout but was lowest during the decline phase in both sexes, especially males. Low transferrin heterozygote survival during the decline coincided with a significant heterozygote deficiency in females whereas in males genotype frequencies did not depart from Hardy-Weinberg equilibrium values throughout th.e study. Twenty-nine suitable ani.mals were released during the decline in five periods from July to November 1974. The proportions of males and transferrin heterozygotes in the released graun were generally greater than in the source population~ In the test enclosures 21% of the released animals continued their movement through the vacant area while 41% (no significant difference) moved through the inhabited enclosure. In the vacant test area, females had a greater tendency than males to continue dispersal whereas no difference was noted in the inhabited area. Low frequency of captures in the tubes, predator disturbances and cold weather forced the termination of the study. The role of dispersal as a population regulating mechanism was further substantiated. The genetic differences between emigrant and resident animals lend support to Howard's hypothesis that a genetic polymorphism influences the tendency to disperse. Support is also given to Myers' and Krebs' contention that among dispersers an additional density dependent polymorphism influences the distance dispersed.

Application of thermal ion-molecule reactions in tackling spectroscopic inferences in inductively coupled plasma mass spectrometry

Part I: Ultra-trace determination of vanadium in lake sediments: a performance comparison using O2, N20, and NH3 as reaction gases in ICP-DRC-MS Thermal ion-molecule reactions, targeting removal of specific spectroscopic interference problems, have become a powerful tool for method development in quadrupole based inductively coupled plasma mass spectrometry (ICP-MS) applications. A study was conducted to develop an accurate method for the determination of vanadium in lake sediment samples by ICP-MS, coupled with a dynamic reaction cell (DRC), using two differenvchemical resolution strategies: a) direct removal of interfering C10+ and b) vanadium oxidation to VO+. The performance of three reaction gases that are suitable for handling vanadium interference in the dynamic reaction cell was systematically studied and evaluated: ammonia for C10+ removal and oxygen and nitrous oxide for oxidation. Although it was able to produce comparable results for vanadium to those using oxygen and nitrous oxide, NH3 did not completely eliminate a matrix effect, caused by the presence of chloride, and required large scale dilutions (and a concomitant increase in variance) when the sample and/or the digestion medium contained large amounts of chloride. Among the three candidate reaction gases at their optimized Eonditions, creation of VO+ with oxygen gas delivered the best analyte sensitivity and the lowest detection limit (2.7 ng L-1). Vanadium results obtained from fourteen lake sediment samples and a certified reference material (CRM031-040-1), using two different analytelinterference separation strategies, suggested that the vanadium mono-oxidation offers advantageous performance over the conventional method using NH3 for ultra-trace vanadium determination by ICP-DRC-MS and can be readily employed in relevant environmental chemistry applications that deal with ultra-trace contaminants.Part II: Validation of a modified oxidation approach for the quantification of total arsenic and selenium in complex environmental matrices Spectroscopic interference problems of arsenic and selenium in ICP-MS practices were investigated in detail. Preliminary literature review suggested that oxygen could serve as an effective candidate reaction gas for analysis of the two elements in dynamic reaction cell coupled ICP-MS. An accurate method was developed for the determination of As and Se in complex environmental samples, based on a series of modifications on an oxidation approach for As and Se previously reported. Rhodium was used as internal standard in this study to help minimize non-spectral interferences such as instrumental drift. Using an oxygen gas flow slightly higher than 0.5 mL min-I, arsenic is converted to 75 AS160+ ion in an efficient manner whereas a potentially interfering ion, 91Zr+, is completely removed. Instead of using the most abundant Se isotope, 80Se, selenium was determined by a second most abundant isotope, 78Se, in the form of 78Se160. Upon careful selection of oxygen gas flow rate and optimization ofRPq value, previous isobaric threats caused by Zr and Mo were reduced to background levels whereas another potential atomic isobar, 96Ru+, became completely harmless to the new selenium analyte. The new method underwent a strict validation procedure where the recovery of a suitable certified reference material was examined and the obtained sample data were compared with those produced by a credible external laboratory who analyzed the same set of samples using a standardized HG-ICP-AES method. The validation results were satisfactory. The resultant limits of detection for arsenic and selenium were 5 ng L-1 and 60 ng L-1, respectively.

Relationship between Socio-Demographic Factors and Familial and Partner Pressures to Conceive in HIV-Positive Women in Ontario

This study examined the relationship between socio-demographic factors and family and partner pressure to conceive in women living with HIV in Ontario, Canada. A total of 490 women, aged 18-52 years were included in the study. The HIV Pregnancy Planning Questionnaire was used to collect data on socio-demographic, medical, and pressure variables. Multivariate logistic regression analysis suggest that increased age, years lived in Canada, and living in Toronto were associated with lower odds, and being married and having 0-1 lifetime births were associated with higher odds of family pressure to conceive. Increased age was associated with lower odds, and being married and living in Toronto were associated with higher odds of partner pressure to conceive. Findings suggest that socio-demographic factors influence the fertility decision-making process. Health care providers should consider socio-demographic factors along with medical factors when assisting women living with HIV and their partners to make informed reproductive decisions.

Socio-demographic factors, smoking, symptoms, morbidities and pulmonary function and quality of life in individuals with a heavy smoking history

Objective: To determine which socio-demographic, exposure, morbidity and symptom variables are associated with health-related quality of life among former and current heavy smokers. Methods: Cross sectional data from 2537 participants were studied. All participants were at ≥2% risk of developing lung cancer within 6 years. Linear and logistic regression models utilizing a multivariable fractional polynomial selection process identified variables associated with health-related quality of life, measured by the EQ-5D. Results: Upstream and downstream associations between smoking cessation and higher health-related quality of life were evident. Significant upstream associations, such as education level and current working status and were explained by the addition of morbidities and symptoms to regression models. Having arthritis, decreased forced expiratory volume in one second, fatigue, poor appetite or dyspnea were most highly and commonly associated with decreased HRQoL. Discussion: Upstream factors such as educational attainment, employment status and smoking cessation should be targeted to prevent decreased health-related quality of life. Practitioners should focus treatment on downstream factors, especially symptoms, to improve health-related quality of life.

Socio-demographic, visual and psychological factors associated with adjustment to vision loss in retinitis pigmentosa

Malgré des recherches intensives portant sur l’hérédité et les aspects biologiques de la rétinite pigmentaire (RP), peu de recherches fondées ont porté sur les aspects psychologiques. Ces quelques études suggèrent que les personnes atteintes de rétinite pigmentaire s’adaptent différemment à la déficience visuelle. Le but de la présente étude était donc de vérifier si les personnes atteintes de rétinite pigmentaire s’adaptaient différemment d’un point de vue psychologique par rapport à des personnes ayant une déficience visuelle causée par une autre pathologie. Des entrevues téléphoniques incluant des personnes ayant la rétinite pigmentaire, la rétinopathie diabétique (RD) et l’albinisme ont été menées. Cinq questionnaires ont été utilisés afin d’évaluer le bien-être psychologique et de recueillir les données démographique. Les résultats de la première étude démontrent qu’il n’existe aucune différence entre les individus atteints de rétinite pigmentaire et ceux ayant d’autres pathologies visuelles d’un point de vue « bien-être psychologique ». En fait, les facteurs démographiques, la baisse de vision, les fluctuations et le type de perte de vision semblent être les seuls facteurs directement corrélés à l’adaptation et au bien-être psychologique. Dans la deuxième étude, aucune différence n’a pu être établie entre les trois types de pathologies. Ce sont plutôt, des facteurs comme la perception des capacités fonctionnelles, l’identité personnelle, l’appréhension de la perception sociale et le niveau d’indépendance qui étaient davantage reliés au bien-être psychologique associé à la déficience visuelle. Les résultats de cette étude suggèrent que les personnes atteintes de Rétinite pigmentaire ne présentent pas de différences au niveau du bien-être psychologique et de l’adaptation. Les facteurs démographiques et psychologiques sont plus importants que la pathologie elle-même.

Environment and Climate Changes During the Late Quaternary: Inferences from Sedimentary Records of Southeastern Arabian Sea

Department of Marine Geology & Geophysics, Cochin University of Science and Technology

Gender Bias and Caste Exclusion in Engineering Admission: Inferences from the Engineering Entrance Examination in Kerala

The major problem of the engineering entrance examination is the exclusion of certain sections of the society in social, economic, regional and gender dimensions. This has seldom been taken for analysis towards policy correction. To lessen this problem a minor policy shift was prepared in the year 2011 with a 50–50 proportion in academic marks and entrance marks. The impact of this change is yet to be scrutinized. The data for the study is obtained from the Nodal Centre of Kerala functioning at Cochin University of Science and Technology under the National Technical Manpower Information System and also estimated from the Centralized Allotment Process. The article focuses on two aspects of exclusion based on engineering entrance examination; gender centred as well as caste-linked. Rank order spectral density and Lorenz ratio are used to cognize the exclusion and inequality in community and gender levels in various performance scales. The article unfolds the fact that social status in society coupled with economic affordability to quality education seems to have significant influence in the performance of students in the Kerala engineering entrance examinations. But it also shows that there is wide gender disparity with respect to performance in the high ranking levels irrespective of social groups