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Nepal Health Research Council and its role in ethics.
No full textThis presentation was given at First National Workshop in Nepal
Hydrochloric Acid Cyclic Exposure Effect on Microleakage of Resin Cements
No full textAbstract: Introduction: Marginal microleakage is one of the major complications associated with bonding to dental porcelain. The extent of microleakage is unpredictable and differs according to the types of cement used. Research has evaluated the effect of common acidic media on the oral cavity and dental restorations. However, little is known about the effect of hydrochloric acid from the stomach in gastroesophageal reflux patients on the microleakage of resin cements under ceramic restorations. Objective: To evaluate microleakage of different resin cements after immersion of zirconia-reinforced lithium silicate crowns (ZLS) in hydrochloric acid (HCl) solution. Materials and Methods: 45 extracted non-carious human molars were prepared for porcelain crowns. Teeth were randomized into three different types of resin cement: RelyX™ UniCem (3M, ESPE), Variolink® Esthetic Dual-cure (Ivoclar Vivadent) and Panavia™ 21 (Kuraray America Inc.). Five replicates were used as a control for each resin cement. ZLS crowns were designed and milled from Celtra® Duo blocks using CEREC CAD/CAM system and then cemented to the prepared teeth using the assigned cement according to the manufacturers' guidelines. Samples were thermal cycled between water temperatures of 5℃ and 55℃ for 5,000 cycles with a 15 second dwell-time after each temperature. In order to mimic one year of clinical time in a patient's mouth, samples of the experiment group were subjected to 91 one hour cycles in HCl (pH 2) followed by one hour in artificial saliva, however samples of the control group were submersed in artificial saliva for 91 hours. After the 91 cycles were completed, specimens were submerged in 50% silver nitrate solution for 24 hours followed by a developer solution for eight hours. The samples were embedded in clear epoxy resin and sectioned in a buccolingual direction at 0.5 mm. Sections were analyzed by a stereomicroscope at a magnification of 10X. Proportion of microleakage was calculated by dividing the total length of the dye penetration by the total length of the restoration. Data were analyzed with the Kruskal-Wallis test and Mann-Whitney U test with the Bonferroni correction. Results: There was a statistically significant difference in median microleakage between the experiment and the control groups (p <0.05) However, there was no statistically significant difference between the three types of cement in the experiment group. Conclusion: Within the limitations of this in-vitro study, the results indicated that all of the resin cements tested in the study exhibited microleakage to some degree, especially when they get exposed to the hydrochloric acid solution.Thesis (M.S.)--Tufts University, 2018.Submitted to the Dept. of Other.Advisor: Ala Ali.Committee: Vasiliki Tsakalelli, Aikaterini Kostagianni, and Sarah Pagni.Keyword: Dentistry
Governance of water use in agriculture: the role of innovation and regime type in sustainable agricultural water management
No full textAbstract: Background Anthropogenic impacts to water systems pose a serious threat to water security across the world. Agriculture, as the largest user and one of the primary polluters of water, plays a central role in water problems. The impending global water crisis cannot be resolved without making agricultural impacts to water more sustainable. Water problems are complex, and many are the result of governance failures. Overcoming them requires innovative solutions attained through good governance. This dissertation presents analysis at different scales, aspects, and contexts of agricultural water governance. Methods This dissertation uses a variety of methods, including technological innovation systems analysis, identifying the presence of Ostrom's eight institutional design principles for sustainable management of common pool resources, and applying the social-ecological systems framework. Chapter 2 identifies blocking mechanisms and opportunities for a sustainability transition involving water harvesting practices in Jordan's rainfed agricultural system. Chapter 3 analyzes the extent to which three different U.S. state-level groundwater governance regimes reflect Water Diplomacy principles for sustainable groundwater quantity management. Chapter 4 identifies conditions within Nebraska's groundwater governance regime that are likely achieve groundwater quality goals relative to nonpoint source nitrate pollution. Results The water harvesting innovation system in Jordan's rainfed agricultural system is negatively impacted by limited financial resources at the national level, and the reliance on donors, as well as by the lack of a common vision for achieving sustainable agriculture water use, and informal and formal institutional problems. In the U.S., findings indicate that groundwater governance regimes reflecting Water Diplomacy principles can lead to adaptive and collaborative approaches to sustainable groundwater abstraction. Findings from Nebraska show that a nested, polycentric groundwater governance regime granting significant authority to empowered and transparent local governance entities can create the enabling conditions for managing groundwater quantity and quality sustainably. Implications Chapter 2 reinforces findings on the utility of the technological innovation systems approach for studying different types of developing country innovation systems in the context of sustainability transitions. It finds that donors can contribute to directionality problems that favor one form of a technology over another. Another finding is that formal and informal institutions can have equal impact in developing country sustainability transitions. Chapter 3 makes an important contribution to the discipline of Water Diplomacy, expanding the concepts to the water governance context. Chapter 4 marks a contribution to the limited literature base on governance of agricultural nonpoint source pollution. Using Nebraska as a case study, it highlights generalizable institutional design principles for the governance of agricultural nonpoint source groundwater pollution.Thesis (Ph.D.)--Tufts University, 2018.Submitted to the Dept. of Agriculture, Food and Environment.Advisor: Timothy Griffin.Committee: Laurens Klerkx, Annette Huber-Lee, and William Masters.Keywords: Natural resource management, Agriculture, and Water resources management
Effect of Diet Quality and Statin Therapy on Coronary Atherosclerosis and Epicardial Adipose Tissue in the Ossabaw Miniature Pig
No full textAbstract: Background and Objective: Current cardiovascular disease risk reduction guidance focuses on overall dietary patterns, rather than single foods and nutrients. However, due to a lack of viable animal models few basic research studies have examined the effect of dietary patterns on coronary artery disease (CAD) development. Additionally, though statin medications are commonly prescribed in concurrence with dietary modifications for the prevention of CAD little data exists on potential diet x statin interactions. Epicardial adipose tissue (EAT) is the perivascular adipose tissue surrounding the coronary arteries. EAT inflammation is thought to potentiate the development of CAD and may be modulated by both diet quality and statin therapy. The objective of this thesis was to assess the effect of diet quality, statin therapy, and their potential interaction on coronary atherosclerosis and EAT using the Ossabaw miniature pig model. Methods: To meet this objective, pigs were fed a Heart Healthy (high in unsaturated fat, unrefined grain, fruits/vegetables [HHD]) or Western diet (high in saturated fat, cholesterol, refined grain [WD]) with or without atorvastatin (HHD+S and WD+S). Diets were food-based and designed to reflect human dietary patterns. Diets were matched for macronutrient composition and fed in isocaloric amounts. The effect of the respective diets and statin therapy was assessed by transcriptomic analyses of gene expression in both the left anterior descending (LAD) coronary artery and the surrounding EAT, and the determination of EAT fatty acid composition by gas chromatography. Results: The WD, relative to the HHD, led to the significant differential expression of 142 genes in the LAD coronary artery. Statin therapy resulted in the significant differential expression of 2 genes (CHRNB4 and an unknown transcript). Pathway analysis of differential expression attributable to the WD indicated the up-regulation of 8 pathways related to immune and inflammatory responses associated with atherosclerosis. EAT of pigs fed the WD, relative to the HHD, had a 12-fold increase of RSAD2; a gene induced by interferon signaling. Statin therapy resulted in the differential expression of 17 genes predominately induced by interferon signaling. A diet x statin interaction was found for 4 genes (IDO1, NKL, MYL4, and MYL7). Pathway analysis indicated an up-regulation of interferon signaling in response to the WD, statin therapy, and a potential diet x statin interaction implying up-regulation in interferon signaling by statin therapy is decreased in EAT of pigs fed the WD. A signature of all differentially expressed genes in EAT had no significant association with a histological assessment of atherosclerosis in the LAD. EAT fatty acid composition largely reflected dietary fat composition. SFAs (total SFAs, capric, lauric, palmitic and stearic acids) had positive associations with two genes involved in interferon signaling (IRF7 and IFIT1) and PTGS2. Total n-6 PUFAs, linoleic acid, and n-3 PUFAs (total n-3 PUFAs, α-linolenic, EPA, DPA and DHA) had strong positive associations with two anti-inflammatory genes (FFAR4 and PPARG), and weak to moderate positive associations with ALOX5. DHA was negatively associated with IL-1β. Conclusions: Collectively these findings indicate that poor diet quality, exemplified by the WD, induces expression of genes implicated in atherosclerosis development in the LAD coronary artery but did not have a similar effect on EAT gene expression. Statin therapy and to a lesser extent diet quality, potentially mediated by SFAs, induced changes in EAT gene expression predominately related to interferon signaling, which was not significantly associated with the development of coronary atherosclerosis. Results from this thesis imply that the Ossabaw miniature pig is a valuable model for the study of dietary patterns and CAD in vivo. However, the modulation of interferon stimulated genes in EAT may not be a mechanism by which diet quality and statin therapy effect the development of CAD in the Ossabaw miniature pig.Thesis (Ph.D.)--Tufts University, 2018.Submitted to the Dept. of Biochemical and Molecular Nutrition.Advisor: Alice Lichtenstein.Committee: Nirupa Matthan, Susan Fried, and William Johnson.Keyword: Nutrition
Thinking beyond Opisthorchis viverrini for risk of cholangiocarcinoma in the lower Mekong region: a systematic review and meta-analysis.
No full textBackground: Cholangiocarcinoma (CCA) is a fatal bile duct cancer associated with infection by the liver fluke, Opisthorchis viverrini, in the lower Mekong region. Numerous public health interventions have focused on reducing exposure to O. viverrini, but incidence of CCA in the region remains high. While this may indicate the inefficacy of public health interventions due to complex social and cultural factors, it may further indicate other risk factors or interactions with the parasite are important in pathogenesis of CCA. This systematic review aims to provide a comprehensive analysis of described risk factors for CCA in addition to O. viverrini to guide future integrative interventions.Keywords: Cholangiocarcinoma, Risk factors, Opisthorchis viverrini, Mekong, Southeast Asia, Thailand, Public health.Springer Open
Edible Mushrooms and Prevention of Atherosclerosis
No full textAbstract: For centuries, mushrooms have been used as medicinal food and, more recently, have been a growing component of a healthy diet. Mushrooms are low in sodium and are good sources of fiber, bioactive compounds, selenium, potassium and vitamin D, all of which are believed to benefit a healthy heart through anti-inflammatory and anti-atherogenic activities. While several types of mushrooms have been studied for their effects on serum lipid profiles, few studies have demonstrated edible mushrooms' effects on atherogenesis. The main objective of this study was to determine the effectiveness of two commonly consumed edible mushrooms, portobello mushroom (PBM) and shiitake mushroom (SHM), on the prevention of atherosclerosis and associated inflammation as well as further investigate the properties of ergothioneine (ERG), a bioactive compound found enriched in mushrooms, on the molecular pathophysiology of atherosclerotic events in both animal and cell culture models. The specific aims of the study included determining the protective impact of mushroom powder supplementation against atherosclerotic risk induced by a high-fat, Western diet in mice, and characterizing ERG's antioxidant and anti-inflammatory activities potentially involved in protection against atherosclerosis. Ldlr-/- mice were fed with one of the following 5 diets for 16 weeks: low-fat (4% fat w/w) control diet (LF-C), high fat (8% fat w/w) control (HF-C) diet, HF-C diet supplemented with 10% PBM powder (HF-PBM), 10% SHM powder (HF-SHM), or a "control mixture", which best matched to the average nutrient levels of the mushroom powders (MIX-C). Body weight was monitored, and body composition was determined using an EchoMRI™ machine. Post-mortem analyses were conducted which include 1) plasma measures of inflammatory markers and lipid profile; 2) quantification of aortic lesions by Oil Red O staining of the descending aorta and histological measures of the aortic tricuspid valve; 3) quantification of monocyte adhesion by ex vivo measure of splenocyte adhesion; 4) real-time polymerase chain reaction assay to quantitate gene expression of adhesion molecules and ERG transporter; 5) quantification of vascular cell adhesion molecule-1 expression in aortic valve by immunohistochemistry. Cell culture assays using human aortic endothelial cells were carried out to further investigate the role of ERG and its transporter in impacting atherosclerosis-associated inflammatory response. The results from this study further support the potential role of high levels of bioactive compounds such as ERG, a potent antioxidant, in suppression of dietary fat-induced atherosclerosis, an inflammatory disorder in arteries. This study is the first to comprehensively characterize the role of mushrooms and ERG and its transporter in atherosclerosis and associated inflammation. These positive findings in this study may encourage further investigation to validate in clinical trials whether increased dietary consumption of mushrooms in the daily diet can reduce cardiovascular disease risk.Thesis (Ph.D.)--Tufts University, 2018.Submitted to the Dept. of Biochemical and Molecular Nutrition.Advisor: Mohsen Meydani.Committee: Dayong Wu, José Ordovas, and Christopher Carman.Keyword: Nutrition
Missed Opportunities: Analyzing New York City's Community-Based Planning Statute
No full textAbstract: Beginning in 1989, New York City Charter Section 197-a gave Community Boards, the most local form of government in New York City, the opportunity to formally engage in community-based planning by sponsoring "Plans for the development, growth, and improvement of the city and of its boroughs and community districts." These 197-a plans are reviewed by the Borough President, Department of City Planning, City Planning Commission, and City Council, and, if adopted, are intended to inform the relevant actions of city agencies. Since 1989, in a city of 59 Community Boards and over eight million residents, only eleven Community Board-sponsored plans have been adopted. Using city documents, especially the 197-a plans, this thesis investigates the value of the 197-a process as a means of community-based planning. The thesis finds that the non-binding nature of these plans prevents them from being an effective method of community-based planning and offers recommendations for improvement.Thesis (M.A.)--Tufts University, 2018.Submitted to the Dept. of Urban and Environmental Policy and Planning.Advisor: Jon Witten.Committee: Sheldon Krimsky.Keywords: Urban planning, and Land use planning
A Micromachined Torsional Electric Field Sensor
No full textAbstract: Neuroimaging is a relatively new discipline within medicine and psychology that is used to study the nervous system and can also help diagnose anomalies in cognitive functions. Unfortunately, the most popular techniques available (i.e. magnetic resonance imaging) are expensive, time-consuming, and inaccessible to most. Furthermore, emerging markets in virtual reality and education are also interested in creating new applications that would primarily rely on brain sensing technology. This research project is part of an internally funded program at Draper that is seeking to develop a sensor that would measure electric fields that are emitted from the outermost layer of the brain (usually ~1mV/m around 10-12Hz). If successful, this method would be relatively cheaper than most commercial techniques with the added benefits of being mobile and providing real-time measurements. In this thesis, a system level model was developed for characterizing the behavior of the device due to an electric field input as well as vibrations. A numerical model is also added to complement the electrostatics to capture any flux diversion that may influence the field strength near the device during operation. The micromachining process as well as the assembly are described. Results show agreement with modeling parameters. First, the expected resonant frequencies of the mechanical modes of the device during each major of the fabrication process are well predicted. Second, the scale factor of the device increases linearly with the amount of voltage applied to the system, which agrees with the model. Results suggest that the sensor's Brownian resolution limit with a 900V bias at resonance (2.5 kHz) will be 2.5 V/m/√Hz, and at low frequencies (~ 10 Hz) will be 1.5 mV/m/√Hz. Due to room vibrations, which are not attenuated by the current single-point laser vibrometry measurement method used for experiments, this resolution limit has not yet been approached. However, if a more optimal measurement scheme were used, that could approach the Brownian limit, which has been done in other MEMS systems, this resolution limit may plausibly be achievable in the future. At resonance this resolution would be nearly three orders of magnitude better than required for brain sensing applications. At low frequencies, the Brownian limit is of the same order as the required resolution. This thesis not only demonstrates the ability of the sensor to measure electric fields, but also develops a model and offers insights on further modifications that can be made to improve sensor performance.Thesis (M.S.)--Tufts University, 2018.Submitted to the Dept. of Mechanical Engineering.Advisor: Robert White.Committee: James Bickford, and Jason Rife.Keyword: Mechanical engineering
The Treacherous Path: The Externalization of Australian Asylum Policy in Southeast Asia.
No full textSubmitted in partial fulfillment of the degree Master of Arts in Law and Diplomacy at the Fletcher School of Law and Diplomacy. Abstract: Australia’s policy of indefinite offshore detention of migrants who attempt to reach its shores by boat has drawn increasing condemnation both at home and abroad, but the Australian government continues to maintain its “Operation Sovereign Borders” program. While significant scholarly attention has been paid to the human rights violations being carried out by Australia, much of this work fails to consider the regional forces and conditions that are driving refugees to risk their lives in the attempt to reach Australia, and the role Australia plays in creating these conditions. This thesis examines the connections between refugee protection policies and practices in Malaysia, Indonesia, and Australia, and concludes that the lack of protection for refugees in Malaysia and Indonesia is a significant driver of migration to Australia by boat, that Australia itself is directly and indirectly contributing to this lack of protection in nearby states through diplomatic pressure and material incentives, and that Australia is harming the human rights of migrants with its focus on deterrence and detention rather than protection. Without a change in Australia’s attitude towards migrants, their human rights (including the right to seek asylum) will continue to be unprotected, leaving them vulnerable to abuse, indefinite detention, refoulement, and other violations
Developing knowledge in engineering science courses: Sense-making and epistemologies in undergraduate mechanical engineering homework sessions
No full textAbstract: Constructing and applying conceptual knowledge about physical systems is a core activity of practicing mechanical engineers. Yet, studies have shown a surprising proportion of graduating engineering students respond to conceptual questions by recalling fragmented facts and equations; they struggle to reason systematically about the causal mechanisms that drive a phenomenon. One activity where students are expected to develop conceptual engineering knowledge in engineering science courses is during the completion of assigned homework problems. This dissertation examined six undergraduate engineering science homework sessions to identify sense-making conversations that may have lead to conceptual knowledge construction. These episodes of sense-making - or in some cases, only bids for sense-making - were analyzed to understand student shifts from task production to knowledge construction. Participants were also interviewed about homework sessions and other assigned tasks in engineering courses to explore their epistemologies. The interviews showed specifically what students believe counts as knowledge in engineering, how they believe they best develop engineering knowledge, and what pedagogical choices by the instructor students notice as productive for their development of knowledge. Findings have implications for the design of engineering science tasks and future research initiatives about conceptual knowledge building during homework sessions.Thesis (Ph.D.)--Tufts University, 2018.Submitted to the Dept. of Mechanical Engineering.Advisor: Kristen Wendell.Committee: Chris Rogers, David Hammer, and Milo Koretsky.Keywords: Mechanical engineering, Education, and Engineering