Male Circumcision Pilot Program in Lilongwe, Malawi

Male circumcision is one method of effective prevention against HIV/AIDS. In Malawi, however, male circumcision is not the predominant practice. Project Malawi conducted a pilot program of male circumcision for villagers with fully subsidized operation costs. After we conducted sensitization programs to create demand for circumcision, the rate of male circumcision has increased. This pilot project allowed us to consider the acceptability of male circumcision in Malawi. Unsafe surgery, a long recovery period, religious beliefs, and age were the most-cited reasons Malawians rejected male circumcision. We also have found three critical barriers—operation cost, transportation cost, and opportunity cost—which can largely explain the limited accessibility of male circumcision procedures. Lastly, in order to scale up male circumcision in Malawi, the importance of delivering the complete information and significant availability issues need to be addressed

Three Essays on Development and Health Economics

This dissertation consists of three essays on development and health economics. In the first chapter, I study how abortion responds to drought-induced transitory income shocks and generates unintended demographic consequences under son preference. I focus on rural Vietnam where low rainfall induces a short-run downturn through a reduction in rice yields. With widely available sex-selection technologies at a low cost under son preference, Vietnamese parents can decide the quantity and the sex of child simultaneously, and it can be directly observed from rich household-level data on abortions. Linking rich microdata on fertility with droughts defined at a fine geographic unit, I first find no effects of droughts on the number and the composition of mothers who conceive. I then find compelling evidence that affected mothers were 30% more likely to get abortions, and the effect was mainly driven by the income effect because most abortions occurred in the pre-harvest season of the next rice crop when consumption smoothing is difficult. Surprisingly, droughts are associated with disproportionately more abortions of female fetuses, which exacerbated the problem of the skewed sex ratio: the affected birth cohorts become more male-biased due to the six abortions of female fetuses to one aborted male fetus, explaining up to approximately 3% of the sex ratio imbalance in rural Vietnam from 2004-2013. While a full rebound in births in approximately two years appears more consistent with the effect on the timing of fertility, the effect on the sex ratio at birth emphasizes that even transitory income shocks can have long-run demographic consequences. Thus, this study can shed light on how the gender gap can persist during a process of economic development. This study also enhances our understanding of the mechanism through which credit-constrained mothers adjust their fertility to smooth consumption. Finally, this study can provide timely evidence to developing countries which witness demographic transitions to low infant mortality but are vulnerable to extreme weather events. In the second chapter (joint work with Anna Choi and Semee Yoon), we study how usual economic activities can harm the health of people who are living in other countries. This study investigates the adverse effect of transboundary particulate matter on fetal health. The adverse health effects at exposures to particulate matter are evident by a handful of experimental and epidemiological studies. The health effects of PM2.5, which has a diameter of less than 2.5 micrometers, are particularly alarming because those hazardous particles are so diminutive that they can easily enter the bloodstream to cause cardiovascular and respiratory diseases. Unlike the consensus in the United States on the negative impact of pollution on human health, the evidence for the relationship between pollution and health in developing countries is not straightforward to quantify due to the lack of accurate pollution and welfare measures as well as the difficulty of finding exogenous variables to purge other endogenous factors. However, this study can circumvent these endogeneity concerns by exploiting the unique meteorological settings which can trigger transboundary transport of particulate matter. The westerlies from heavily polluted eastern China carry pollutants to South Korea, thereby intermittently exposing the population to pollution above threshold levels. We find that conditional on local weather and pollution trends, one standard deviation increase in Beijing’s PM2.5 explains 1.1% of standard deviation of daily fetal mortality rates in South Korea. We hope that the results of this research can suggest the first accurate cost estimates of transboundary fine-particle to highlight the urgent need for regional cooperation. In the third chapter, the unintended consequences of economic activities on human capital in developing countries can be further emphasized by a randomized control trial study (joint with Hyuncheol Bryant Kim, Booyuel Kim and Cristian Pop-Eleches). We use a four-year long follow-up of an intervention based on a two-step randomized design within classrooms in secondary schools in Malawi to understand the impact of male circumcision on risky sexual behaviors and the role that peers play in the decision and consequences of being circumcised. Although medical male circumcision can reduce HIV infections, its preventive effects may diminish if circumcised men are more likely to engage in risky sexual behaviors. Despite a number of short-term studies of risk compensation following male circumcision, there is scant rigorous evidence on how these behavioral responses change in the longer term. This study is the first evaluation of risk compensation over such a long follow-up period. Our analysis yields three main results. First, we show that the intervention substantially increased the demand for male circumcision for the students assigned to the treatment group. Second, we find evidence of positive peer effects in the decision to get circumcised among untreated students. Third, we find evidence of risk compensation using biomarkers of sexually transmitted infection for those who got circumcised due to the intervention, but not for those induced by peer effects

Effects of large-scale environment on the assembly history of central galaxies

We examine whether large-scale environment affects the mass assembly history of their central galaxies. To facilitate this, we constructed dark matter halo merger trees from a cosmological N-body simulation and calculated the formation and evolution of galaxies using a semi-analytic method. We confirm earlier results that smaller halos show a notable difference in formation time with a mild dependence on large-scale environment. However, using a semi-analytic model, we found that on average the growth rate of the stellar mass of central galaxies is largely insensitive to large-scale environment. Although our results show that the star formation rate (SFR) and the stellar mass of central galaxies in smaller halos are slightly affected by the assembly bias of halos, those galaxies are faint, and the difference in the SFR is minute, and therefore it is challenging to detect it in real galaxies given the current observational accuracy. Future galaxy surveys, such as the BigBOSS experiment and the Large Synoptic Survey Telescope, which are expected to provide observational data for fainter objects, will provide a chance to test our model predictions.Comment: 7 pages, 5 figure

Merger relics of cluster galaxies

Context. Sheen and collaborators recently found that a surprisingly large portion (38%) of massive early-type galaxies in heavy clusters show strong merger-related disturbed features. This contradicts the general understanding that massive clusters are hostile environments for galaxy mergers. Considering the significance of mergers in galaxy evolution, it is important to understand this. Aims. We aim to present a theoretical foundation that explains galaxy mergers in massive clusters. Methods. We used the N-body simulation technique to perform a cosmological-volume simulation and derive dark-halo merger trees. Then, we used the semi-analytic modeling technique to populate each halo with galaxies. We ran hydrodynamic simulations of galaxy mergers to estimate the lifetime of merger features for the imaging condition used by Sheen and collaborators. We applied this merger feature lifetime to our semi-analytic models. Finally, we counted the massive early-type galaxies in heavy model clusters that would show strong merger features. Results. While there still are substantial uncertainties, our preliminary results are remarkably close to the observed fraction of galaxies with merger features. Key ingredients for the success are twofold: firstly, the subhalo motion in dark haloes has been accurately traced, and, second, the lifetime of merger features has been properly estimated. As a result, merger features are expected to last very long in cluster environments. Many massive early-type galaxies in heavy clusters therefore show merger features not because they experience mergers in the current clusters in situ, but because they still carry their merger features from their previous halo environments. Conclusions. Investigating the merger relics of cluster galaxies is potentially important, because it uniquely allows us to backtrack the halo merger history.Comment: 4 pages, 3 figures, accepted for publication in A&A Research Not

Turning behaviors of T cells climbing up ramp-like structures are regulated by myosin light chain kinase activity and lamellipodia formation

T cells navigate diverse microenvironments to perform immune responses. Micro-scale topographical structures within the tissues, which may inherently exist in normal tissues or may be formed by inflammation or injury, can influence T cell migration, but how T cell migration is affected by such topographical structures have not been investigated. In this study, we fabricated ramp-like structures with a 5 mu m height and various slopes, and observed T cells climbing up the ramp-like structures. T cells encountering the ramp-like structures exhibited MLC accumulation near head-tail junctions contacting the ramp-like structures, and made turns to the direction perpendicular to the ramp-like structures. Pharmacological study revealed that lamellipodia formation mediated by arp2/3 and contractility regulated by myosin light chain kinase (MLCK) were responsible for the intriguing turning behavior of T cells climbing the ramp-like structures. Arp2/3 or MLCK inhibition substantially reduced probability of T cells climbing sharp-edged ramp-like structures, indicating intriguing turning behavior of T cells mediated by lamellipodia formation and MLCK activity may be important for T cells to access inflamed or injured tissues with abrupt topographical changes.11Ysciescopu

Technical Adequacy of Curriculum-Based Measures in Writing in Grades 1–3

The purpose of this study was to investigate evidence of reliability, criterion validity, and grade-level differences of curriculum-based measures of writing (CBM-W) with 612 students in grades 1–3. Four scoring procedures (words written, words spelled correctly, correct word sequences, and correct minus incorrect word sequences) were used with two CBM-W tasks (picture–word and story prompt) during fall, winter, and spring of one academic year. A subsample of participants (n = 244) were given a criterion measure in spring of the academic year. Pearson’s r coefficients were calculated to determine evidence of alternate form reliability and criterion validity, and a MANOVA was used to detect significant growth within and across grade levels. Results indicated that scores on both CBM-W tasks had adequate reliability and validity coefficients in grades 2–3 and mixed results in grade 1. Significant growth was detected within and across all grades at each time point on each task. Implications for research and practice are discussed

X-ray: Discovering DRAM Internal Structure and Error Characteristics by Issuing Memory Commands

The demand for accurate information about the internal structure and characteristics of dynamic random-access memory (DRAM) has been on the rise. Recent studies have explored the structure and characteristics of DRAM to improve processing in memory, enhance reliability, and mitigate a vulnerability known as rowhammer. However, DRAM manufacturers only disclose limited information through official documents, making it difficult to find specific information about actual DRAM devices. This paper presents reliable findings on the internal structure and characteristics of DRAM using activate-induced bitflips (AIBs), retention time test, and row-copy operation. While previous studies have attempted to understand the internal behaviors of DRAM devices, they have only shown results without identifying the causes or have analyzed DRAM modules rather than individual chips. We first uncover the size, structure, and operation of DRAM subarrays and verify our findings on the characteristics of DRAM. Then, we correct misunderstood information related to AIBs and demonstrate experimental results supporting the cause of rowhammer. We expect that the information we uncover about the structure, behavior, and characteristics of DRAM will help future DRAM research.Comment: 4 pages, 7 figure

Rhus verniciflua Stokes against Advanced Cancer: A Perspective from the Korean Integrative Cancer Center

Active anticancer molecules have been searched from natural products; many drugs were developed from either natural products or their derivatives following the conventional pharmaceutical paradigm of drug discovery. However, the advances in the knowledge of cancer biology have led to personalized medicine using molecular-targeted agents which create new paradigm. Clinical benefit is dependent on individual biomarker and overall survival is prolonged through cytostatic rather than cytotoxic effects to cancer cell. Therefore, a different approach is needed from the single lead compound screening model based on cytotoxicity. In our experience, the Rhus verniciflua stoke (RVS) extract traditionally used for cancer treatment is beneficial to some advanced cancer patients though it is herbal extract not single compound, and low cytotoxic in vitro. The standardized RVS extract's action mechanisms as well as clinical outcomes are reviewed here. We hope that these preliminary results would stimulate different investigation in natural products from conventional chemicals