Three Essays On Internal Migration And Risk Factors For Non-Communicable Diseases (ncds) In Low- And Middle-Income Countries (lmics)

Low- and middle-income countries (LMICs) have been experiencing extensive internal migration, which is closely associated with the increasing prevalence of risk factors for non-communicable diseases (NCDs). In this dissertation, I study the impact of internal migration on main NCD risk factors across three diverse LMIC contexts: China, Indonesia, and Malawi. In Chapter 1, I introduce the background, motivation, and research goals of this dissertation. In Chapter 2, I use data from the 2011 China Health and Retirement Longitudinal Study (CHARLS) to examine the associations between rural-urban migration and three main NCD risk factors, hypertension, obesity, and abdominal obesity, among older adults aged 45 or above. I find that rural-urban migrants have significantly higher chances of getting all three risk factors than rural non-migrants, suggesting a negative impact of rural-urban migration on health outcomes. Meanwhile, the number of years lived in cities significantly predicts being hypertensive, implying a “years since migration (YSM)” effect. In addition, health-related behaviors examined play a very limited role in mediating the association between migration and health. In Chapter 3, using data from the fourth and fifth waves of the Indonesia Family Life Survey (IFLS), I study the impact of rural-urban migration on overweight status in Indonesia. I find that rural-urban migration is significantly associated with being overweight, and the association is significantly stronger among women than men, demonstrating a gender disparity in health. Moreover, the number of years lived in cities does not predict overweight status, and health behavioral factors still explain little of the association between migration and health. In Chapter 4, I use data from the 2008 and 2019 waves of the Malawi Longitudinal Study of Families and Health (MLSFH) to investigate the impact of internal migration, not only rural-urban but also rural-rural, on weight status in Malawi. I find that rural-urban and rural-rural migration are both significantly associated with increased Body Mass Index (BMI) and that rural-rural migration significantly predicts being overweight. Meanwhile, the impact of rural-rural migration is significantly stronger among women than men, showing a gendered impact of migration on health. In Chapter 5, I summarize findings from the three main chapters and discuss their implications for policymaking and future research

SGLT2 inhibitor plus DPP‐4 inhibitor as combination therapy for type 2 diabetes: A systematic review and meta‐analysis

To assess the efficacy and safety of sodium‐glucose co‐transporter 2 (SGLT2) inhibitors plus a dipeptidyl peptidase‐4 (DPP‐4) inhibitor in patients with type 2 diabetes mellitus (T2DM), we performed a systematic review and meta‐analysis of 14 randomized controlled trials (RCTs) involving 4828 patients. Compared with a DPP‐4 inhibitor, SGLT2 inhibitor/DPP‐4 inhibitor combination therapy was significantly associated with a decrease in glycaemic control (HbA1c, −0.71%; fasting plasma glucose [FPG], −25.62 mg/dL; postprandial plasma glucose, −44.00 mg/dL), body weight (−2.05 kg) and systolic blood pressure (−5.90 mm Hg), but an increase in total cholesterol (TC) of 3.24%, high‐density lipoprotein of 6.15% and low‐density lipoprotein of 2.55%. Adding a DPP‐4 inhibitor to an SGLT2 inhibitor could reduce HbA1c by −0.31%, FPG by −8.94 mg/dL, TC by −1.48% and triglycerides by −3.25%. Interestingly, low doses of an SGLT2 inhibitor in the combination has similar or even better efficacy in some aspects than high doses. Similar adverse events were observed for the combination therapy, with the exception of genital infection vs DPP‐4 inhibitor (risk ratio [RR], 5.31) and consistent genital infection vs an SGLT2 inhibitor (RR, 0.61). Further studies are warranted to confirm these results

Compressive Property Comparisons Between Laser Engineered Net Shaping of In Situ TiBw-TMCs and Cp-Ti Materials

Titanium (Ti) and its alloys are widely used in chemical, astronautical, and biomedical industries. However, their poor load endurance properties affect their fields of applications especially under severe loading conditions. To enhance these properties, TiBw reinforcement was synthesized by in situ chemical reaction between elemental Ti and boron. Strong interfacial bonding between TiBw reinforcement and Ti matrix was obtained due to the in situ chemical reaction. Owing to its capability of producing difficult-to-machine bulk composites with uniform properties, laser engineered net shaping (LENS) technique was utilized to fabricate TiBw reinforced Ti matrix bulk composites. Few researches have been reported on these three-dimensional metal based bulk composites by using LENS. In this work, effects of TiBw reinforcement and laser power on compressive properties were investigated. The microstructures of the fabricated parts were observed and analyzed by using scanning electron microscopy.Mechanical Engineerin

Microstructural and Mechanical Performance of Al2O3 Nanoparticle Reinforced 17-4 PH Stainless Steel Bulk Composite Parts Fabricated by Laser Engineered Net Shaping Process

Alloy 17-4 PH (AISI 630) is a precipitation-hardening martensitic stainless steel that has been extensively employed in the industries of aerospace, marine, and chemical. In this study, bulk parts of both 17-4 PH and Al2O3 reinforced 17-4 PH composites were fabricated on a steel substrate by laser engineered net shaping (LENS) process to investigate the effects of Al2O3 reinforcements on the part performance. The 17-4 PH powders were pre-mixed with Al2O3 nanoparticles by ball milling. The microstructures of both parts were observed using scanning electron microscopy and mechanical properties including microhardness and compressive properties were evaluated by means of a Vickers microhardness tester and a universal tester, respectively. The results indicate that Al2O3 reinforced 17-4 PH composite parts fabricated by LENS process exhibited superior microhardness and compressive properties as compared to pure 17-4 PH parts.Mechanical Engineerin

Multiobjective Optimization Design of Time-Modulated Concentric Circular Ring Arrays

A multiobjective approach based on the third evolution step of generalized differential evolution (GDE3) algorithm is proposed for optimizing the time-modulated array (TMA) in this paper. Different from the single-objective optimization, which optimizes a weighted sum of the peak sidelobe level (PSLL) and the peak sideband level (PSBL) of the array, the multiobjective algorithm treats the PSLL and the PSBL as two distinct objectives that are to be optimized simultaneously. Furthermore, not only one outstanding optimization result can be acquired but also a set of solutions known as Pareto front is obtained by using the GDE3 algorithm, which will guide the design of time-modulated array more effectively. Users can choose one appropriate outcome which has a suitable tradeoff between the PSLL and the PSBL. This approach is illustrated through a time-modulated concentric circular ring array (CCRA). The optimal parameters and the corresponding radiation patterns are presented at last. Experimental results reveal that the multiobjective optimization can be an effective approach for the TMA synthesis problems

Genome-wide DNA methylation and gene expression analyses in monozygotic twins identify potential biomarkers of depression

Depression is currently the leading cause of disability around the world. We conducted an epigenome-wide association study (EWAS) in a sample of 58 depression score-discordant monozygotic twin pairs, aiming to detect specific epigenetic variants potentially related to depression and further integrate with gene expression profile data. Association between the methylation level of each CpG site and depression score was tested by applying a linear mixed effect model. Weighted gene co-expression network analysis (WGCNA) was performed for gene expression data. The association of DNA methylation levels of 66 CpG sites with depression score reached the level of P < 1 x 10(-4). These top CpG sites were located at 34 genes, especially PTPRN2, HES5, GATA2, PRDM7, and KCNIP1. Many ontology enrichments were highlighted, including Notch signaling pathway, Huntington disease, p53 pathway by glucose deprivation, hedgehog signaling pathway, DNA binding, and nucleic acid metabolic process. We detected 19 differentially methylated regions (DMRs), some of which were located at GRIK2, DGKA, and NIPA2. While integrating with gene expression data, HELZ2, PTPRN2, GATA2, and ZNF624 were differentially expressed. In WGCNA, one specific module was positively correlated with depression score (r = 0.62, P = 0.002). Some common genes (including BMP2, PRDM7, KCNIP1, and GRIK2) and enrichment terms (including complement and coagulation cascades pathway, DNA binding, neuron fate specification, glial cell differentiation, and thyroid gland development) were both identified in methylation analysis and WGCNA. Our study identifies specific epigenetic variations which are significantly involved in regions, functional genes, biological function, and pathways that mediate depression disorder.Peer reviewe

Genome-wide DNA methylation analysis of pulmonary function in middle and old-aged Chinese monozygotic twins

Background Previous studies have determined the epigenetic association between DNA methylation and pulmonary function among various ethnics, whereas this association is largely unknown in Chinese adults. Thus, we aimed to explore epigenetic relationships between genome-wide DNA methylation levels and pulmonary function among middle-aged Chinese monozygotic twins. Methods The monozygotic twin sample was drawn from the Qingdao Twin Registry. Pulmonary function was measured by three parameters including forced expiratory volume the first second (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio. Linear mixed effect model was used to regress the methylation level of CpG sites on pulmonary function. After that, we applied Genomic Regions Enrichment of Annotations Tool (GREAT) to predict the genomic regions enrichment, and used comb-p python library to detect differentially methylated regions (DMRs). Gene expression analysis was conducted to validate the results of differentially methylated analyses. Results We identified 112 CpG sites with the level of P < 1 x 10(-4) which were annotated to 40 genes. We identified 12 common enriched pathways of three pulmonary function parameters. We detected 39 DMRs located at 23 genes, of which PRDM1 was related to decreased pulmonary function, and MPL, LTB4R2, and EPHB3 were related to increased pulmonary function. The gene expression analyses validated DIP2C, ASB2, SLC6A5, and GAS6 related to decreased pulmonary function. Conclusion Our DNA methylation sequencing analysis on identical twins provides new references for the epigenetic regulation on pulmonary function. Several CpG sites, genes, biological pathways and DMRs are considered as possible crucial to pulmonary function.Peer reviewe

An Edge-Preserved Image Denoising Algorithm Based on Local Adaptive Regularization

Image denoising methods are often based on the minimization of an appropriately defined energy function. Many gradient dependent energy functions, such as Potts model and total variation denoising, regard image as piecewise constant function. In these methods, some important information such as edge sharpness and location is well preserved, but some detailed image feature like texture is often compromised in the process of denoising. For this reason, an image denoising method based on local adaptive regularization is proposed in this paper, which can adaptively adjust denoising degree of noisy image by adding spatial variable fidelity term, so as to better preserve fine scale features of image. Experimental results show that the proposed denoising method can achieve state-of-the-art subjective visual effect, and the signal-noise-ratio (SNR) is also objectively improved by 0.3–0.6 dB