SamACO: variable sampling ant colony optimization algorithm for continuous optimization

An ant colony optimization (ACO) algorithm offers algorithmic techniques for optimization by simulating the foraging behavior of a group of ants to perform incremental solution constructions and to realize a pheromone laying-and-following mechanism. Although ACO is first designed for solving discrete (combinatorial) optimization problems, the ACO procedure is also applicable to continuous optimization. This paper presents a new way of extending ACO to solving continuous optimization problems by focusing on continuous variable sampling as a key to transforming ACO from discrete optimization to continuous optimization. The proposed SamACO algorithm consists of three major steps, i.e., the generation of candidate variable values for selection, the ants’ solution construction, and the pheromone update process. The distinct characteristics of SamACO are the cooperation of a novel sampling method for discretizing the continuous search space and an efficient incremental solution construction method based on the sampled values. The performance of SamACO is tested using continuous numerical functions with unimodal and multimodal features. Compared with some state-of-the-art algorithms, including traditional ant-based algorithms and representative computational intelligence algorithms for continuous optimization, the performance of SamACO is seen competitive and promising

Co-occurrence of shedding Herpes Simplex Virus type-2 (HSV-2), Human Papilloma Virus (HPV) and Human Immunodeficiency Virus 1 (HIV-1) in the female genital tract among HIV-infected women

Introduction: Human Immunodeficiency Virus remains as one of the largest pandemics in the world, with the prevalence of more than 70% of HIV-infected individual reside in Sub-Saharan Africa. Moreover, other sexually transmitted viral infection such as Human Papillomavirus and Herpes Simplex Virus also show a high prevalence in Sub-Saharan Africa. Recent studies show the presence of other viral STI in the genital region may have increased HIV shedding in the genital region. However, it not clearly known if the presence of ART or HIV may affect the shedding of other viral STI in the genital region and if the combination of other viral STI treatment and ART is necessary to treat an individual with multiple STI infection. Methods: This is a secondary data analysis study, based on analysing the data collected from a single-site, double-blinded randomized control study (2-IUD study). The research site was the Gugulethu Community Health Centre, Cape Town, South Africa and samples were collected between 2014 and 2018. Analysis was conducted on genital tract specimens of study participants obtained via the Menstrual Cup (MC) and Endocervical Swabs (ECS), collected at baseline, 3 and 6 months’ follow up visit from randomly selected 52 ART-Naïve participants and 56 age-matched women from the ART-Using group of the primary study. Logistic regression models were constructed to measure the associations between possible risk factors and viral STIs. Results are presented as odds ratios (OR) with 95% confidence intervals (CI). Results: ART-Naïve women had higher rates of HIV shedding in the genital tract at each visit. However, more than half of women using ART, most of them virally suppressed, had detectable genital HIV at one or more visits. Most of the participants showed pre-exposure to HSV-2, but shedding of HSV-2 was substantially less common. HPV was detected in 72% of the participants, with no significant difference by ART status. Overall, 70.3% of samples had at least one viral pathogen detected - 60.4% among ART-Using women compared to 82.8% in ART-Naïve women (P<0.001). Compared to ART-Naïve women, ART-Using women were significantly less likely to have co-occurrence of viral shedding overall. However, ART-Using women with higher VL had levels of viral co-occurrence similar to those of ART-Naïve women. Conclusion: Our analysis demonstrated that the ART-Using women were less likely to shed HIV, HSV-2, HPV and viral STI co-infection in the genital tract compared to ART-Naïve women. This may be be driven by plasma VL levels where ART-Using women with lower VL are less likely to shed these viruses compared to women with elevated VL, including those not on ART

The development of penguinpox virus (PEPV) as a vaccine vector : transfer vector construction and rescue of virus growth in rabbit kidney cells (RK-13) by vaccinia virus K1

Includes bibliographical references (leaves 131-137).Of the many vaccine trials which have taken place, the most promising results have been obtained from the recent phase 3 clinical trial which tested the ability of a dual protein and Canarypox virus recombinant to protect humans against HIV-1 infections. Because poxviruses are being developed as vaccine vectors against a number of diseases, it is important to continue the search for novel poxvirus vectors, in particular, those that do not cross-neutralize one another. This thesis describes the preliminary work performed on the development of Penguinpox virus (PEPV) as a vaccine vector

Three Essays on Marriage, Health and Social Stratification in China

China has undergone remarkable socioeconomic and demographic transitions in recent decades. In the wake of these changes, a large body of research has investigated the ways that socioeconomic status shapes family formation, labor market outcomes, and health and wellbeing. While sociological research in China disproportionately focuses on socioeconomic status as an important factor in understanding family formation, labor market outcomes and health disparities, there is little attention to health as an important human capital dimension—one that might matter for labor market outcomes, and might be related to marriage. By utilizing the China Health and Nutrition Survey, a large-scale, longitudinal survey, this study enables investigation of competing hypotheses about linkages among marriage, health and social stratification over the life course. Chapter one of the dissertation addresses how marriage is related to an individual’s health over the life course. Chapter 2 investigates a) the association between marital transition and weight change and b) how this association differs by gender. Chapter 3 investigates the association between weight status and labor market opportunities, and how this relationship varies by gender and level of urbanization of communities, given rising concerns about labor market discrimination and imbalanced regional development. Empirical results show that marriage is related to individuals’ self-rated health over the life course, but that the relationship varies by gender. Among men, there are no health differences by marital status after accounting for selection bias. Among women, health differences between those who are single and those who are married are trivial, but health benefits of marriage emerge when comparing married and widowed women. Moreover, the health benefits of marriage for women erode over the life course. Married people are also heavier than non-married people, and non-married women lose more weight than their married counterparts. This phenomenon may be due to parental pressures to marry and other attributes of the Chinese context. Furthermore, heavier people--men and women--also face more difficulties in finding a job, and these difficulties are aggravated in highly-urbanized communities. In summary, this dissertation shows that health disparities are closely tied to marriage and to labor market opportunities in China