Statistical Methods For Detecting Genetic Risk Factors of a Disease with Applications to Genome-Wide Association Studies

This thesis aims to develop various statistical methods for analysing the data derived from genome wide association studies (GWAS). The GWAS often involves genotyping individual human genetic variation, using high-throughput genome-wide single nucleotide polymorphism (SNP) arrays, in thousands of individuals and testing for association between those variants and a given disease under the assumption of common disease/common variant. Although GWAS have identified many potential genetic factors in the genome that affect the risks to complex diseases, there is still much of the genetic heritability that remains unexplained. The power of detecting new genetic risk variants can be improved by considering multiple genetic variants simultaneously with novel statistical methods. Improving the analysis of the GWAS data has received much attention from statisticians and other scientific researchers over the past decade. There are several challenges arising in analysing the GWAS data. First, determining the risk SNPs might be difficult due to non-random correlation between SNPs that can inflate type I and II errors in statistical inference. When a group of SNPs are considered together in the context of haplotypes/genotypes, the distribution of the haplotypes/genotypes is sparse, which makes it difficult to detect risk haplotypes/genotypes in terms of disease penetrance. In this work, we proposed four new methods to identify risk haplotypes/genotypes based on their frequency differences between cases and controls. To evaluate the performances of our methods, we simulated datasets under wide range of scenarios according to both retrospective and prospective designs. In the first method, we first reconstruct haplotypes by using unphased genotypes, followed by clustering and thresholding the inferred haplotypes into risk and non-risk groups with a two-component binomial-mixture model. In the method, the parameters were estimated by using the modified Expectation-Maximization algorithm, where the maximisation step was replaced the posterior sampling of the component parameters. We also elucidated the relationships between risk and non-risk haplotypes under different modes of inheritance and genotypic relative risk. In the second method, we fitted a three-component mixture model to genotype data directly, followed by an odds-ratio thresholding. In the third method, we combined the existing haplotype reconstruction software PHASE and permutation method to infer risk haplotypes. In the fourth method, we proposed a new way to score the genotypes by clustering and combined it with a logistic regression approach to infer risk haplotypes. The simulation studies showed that the first three methods outperformed the multiple testing method of (Zhu, 2010) in terms of average specificity and sensitivity (AVSS) in all scenarios considered. The logistic regression methods also outperformed the standard logistic regression method. We applied our methods to two GWAS datasets on coronary artery disease (CAD) and hypertension (HT), detecting several new risk haplotypes and recovering a number of the existing disease-associated genetic variants in the literature

The effects of chemical pressurization on screen electrode fuel cells

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (leaves 29-30).A large amount of fuel cell research focuses on porous gas diffusion (PGD) fuel cells which currently produce the best power density. However, this sect of fuel cell technology has many obstacles to overcome before becoming a viable large scale source or power. Nevertheless, alternatives to PGD fuel cells exist. Fluidized bed electrodes (FBE), packed bed electrodes, and packed screen electrodes are discussed and analyzed in this thesis. Fluidization provides a number of benefits, but also presents a different set of obstacles. One of the largest benefits of fluidization is the possibility of using chemical pressurization to increase the reactant concentration. Perfluorocarbons (PFC), currently being used in biomedical applications as oxygen carriers in plasma, can be used to effectively raise the cathode oxygen concentration. This thesis will propose a model of perfluorocarbon emulsions as applied to an oxygen half cell. The model is first developed for the simple case of a rotating disk electrode (RDE). The predictions of this model are then compared with data obtained from a RDE experiment with and without the use of PFC's. The model is then extended to the use of packed screen electrodes.(cont.) The key findings of the model include the relationships between bed length, power output, oxygen concentration, and volumetric flow rate. Finally, the thesis is concluded with a description of the setup created to test the predictions of the model and proposals for future extensions of this research.by Ali Ahmed.S.B

Why do students opt not to sit for SEC examinations at the end of their compulsory education?

In Malta, the number of female students registering for Secondary Education Certificate (SEC) examinations at the end of their compulsory schooling consistently outnumbers that of male students, a higher percentage of female students register for Matriculation Certificate Examinations and acquire the Matriculation Certificate and more female students than male students start University courses and eventually graduate per academic year. Statistics available show relatively low numbers of students, especially male students engaging in further education and this led the Gender Issues Committee of the University of Malta to ask: why do some students opt not to participate in further education but to drop out of the system at the earliest opportunity? This prompted the Gender Issues Committee to embark on research attempting to answer this question. The study carried out with school guidance teachers and students who opted not to sit for any SEC examinations also sought to determine whether there were any differences between reasons given by boys and those given by girls among other things. The results show that students who do not sit for any SEC examinations come mainly from Area Secondary Schools and the main reasons given were that the examinations are too difficult for them; that they do not like school; that they wished to stop studying; and that these students wanted seek employment. The dire necessity for higher levels of certification and the need for vocational courses at compulsory school level were among the conclusions reached through this study.peer-reviewe

PRINCIPLE BARRIERS TO INTERNATIONAL TRADEAND IT’S EFFECT ON LEBANESE FINANCIAL INSTITUTIONS

This paper provides an overview of the principal barriers of international trade and the sanctions imposed on countries and its effect on the Lebanese economy. Illustrating the barriers effect by two examples one related to decreasing tariffs on imports from Latin America and the other on protectionism system implemented in Europe. Then studying two other cases in the Lebanese market where barriers leave a huge effect on the businesses in Lebanon and giving examples faced in two different businesses in Lebanon in the financial sector. International trade promoted high standard of living for trading nations. Hence, despite its various unpleasant effects to some, it is still the best to practice free international trade since it is being a stimulator of the rise of global economies leaving economies having economic and social benefits. This paper attempts to bring to light to the free-trade and the general barriers international trade faces presently and some examples of the unions between two countries to form the best trade with fewer obstacles. Moreover, I would be lightening on Cash+; money transfer company and relate it to the barriers it faces in everyday business. As well as, giving a quick overview of the banks in Lebanon, we will talk about the offering of trade finance products which cut the risk of exporting products; the substantial risk between the buyer and seller. These cornerstones (banks) are a major pillar in the country leaving space for the neighbor countries’ citizens to benefit from their services too. As well as, relating that to the bans and the sanctions imposed on the Syrian country and the Syrians and concentrating on the effect of the international barriers on Syria as a country and on Syrian citizens and their work relating it to the banking sector in Lebanon. In the last part, an example on a closed versus open economy is mentioned with numbers to end up with why recommendations and solutions listed are important to all nations

BUILDING PERMIT: A CRITICAL REVIEW OF THE LEGALFRAMEWORK IN LEBANON

The Building Permit (BP) is a required administrative authorization issued by public authorities. It ensures that the planned construction is abiding by the legal framework governing the construction works in the targeted are or zone. In Lebanon, the Construction Law, No.646/2004 regulates the issuance of BPs. The technical and legal procedures involve require the engagement of various administrative authorities. In this context, three institutions are involved. At first, the Order of Engineers and Architects (OEA), the General Directorate of Urban Planning (GDUP) and the relevant local authorities on the Municipal level. However, as of 2014, the Ministry of the Interior issued four circulars, supposedly, aiming at facilitating the issuance of the BP. As result, it allowed for the circumvent of the notification and mandatory verification by OEA and GDUP. This concentration of power within the direct executive local authorities was portrayed as a way to trim down the massive displacements towards urban centers. Moreover, it aimed at lowering the rate of illegal building plots the disadvantaged peripheries. This article intends is to investigate the legality of these circulars vis-à-vis the Lebanese Construction Law. It will be closely assessing the impact of the 2017 circulars on the urban and rural environment. Moreover, it will inquire on the potential risks due to the sidelining of the main technical institutions. It is aimed that this article will contribute to the overall national debate regarding the healthiness and the legality of executive degrees and their impact on the everyday life of the resident

E-commerce and the Market Structure of Retail Industries

While a fast-growing body of research has looked at how the advent and diffusion of e- commerce has affected prices, much less work has investigated e-commerce's impact on the number and type of firms operating in an industry. This paper theoretically and empirically takes up the question of which producers most benefit and most suffer as consumers switch to purchasing products online. We specify a general industry model involving consumers with differing search costs buying products from heterogeneous-type producers. We interpret e-commerce as having created reductions in consumers' search costs. We show how such shifts in the search cost distribution reallocate market shares from an industry's low- type producers to its high-type businesses. We test the model using data for two industries in which e-commerce has arguably decreased consumers' search costs considerably: travel agencies and bookstores. We find evidence in both industries of the market share shifts predicted by the model. Interestingly, while both industries experienced similar changes, the specific mechanisms through which e-commerce induced them were different. For travel agencies, the shifts reflected aggregate changes driven by airlines' reductions in agent commissions as consumers started buying tickets online. For bookstores, on the other hand, industry-wide declines in small book stores reflected aggregated market-specific impacts, evidenced by the fact that more small-store exit occurred in those local markets where consumers' use of e-commerce channels grew fastest

Cultural intelligence and leadership style in the education sector

Purpose: Schools in UAE are multicultural in nature. In this context, cultural intelligence (CQ) is a tool, which can increase an individual’s ability to interact with people outside his/her culture. The purpose of this paper is to explore the perceptions of the school leaders regarding the key influences of cultural intelligence on their ability to adapt their leadership style in the Abu Dhabi Education Sector. Design/methodology/approach: An extensive review of the literature was carried out to acknowledge the cultural intelligence and leadership style adaptability concepts. This research has adopted a qualitative method of inquiry. Data for the study have been collected from three focus groups with 14 schools leaders in the Emirate of Abu Dhabi. Findings: This pilot study reveals that cultural intelligence has some influence on the school leaders’ ability to adapt their leadership style within a diverse work environment. This influence is complex in nature and multiple factors have been identified. Research limitations/implications: The main limitations of this study are associated with the small sample size. Regarding the implications, while this study was conducted in a UAE cultural context, it can be extended to other Gulf countries. Future research should prompt educational leaders, administrators, students, and research academics to further consider the impact of cultural intelligence on leadership style. Practical implications: This study contributes towards cultural intelligence literature. Schools should provide cultural training to managers before appointing them to leadership positions, which helps in understanding the culture which they are going to operate in, and effectively manage their drives, workforce, students, and the community. Originality/value: The paper highlights six core factors that influence the ability of school leaders to adapt their leadership style in culturally diverse environments. These preliminary factors need to be examined further to validate the dimensions of leadership adaptability in various contexts