De novo human genome assemblies reveal spectrum of alternative haplotypes in diverse populations.

The human reference genome is used extensively in modern biological research. However, a single consensus representation is inadequate to provide a universal reference structure because it is a haplotype among many in the human population. Using 10× Genomics (10×G) "Linked-Read" technology, we perform whole genome sequencing (WGS) and de novo assembly on 17 individuals across five populations. We identify 1842 breakpoint-resolved non-reference unique insertions (NUIs) that, in aggregate, add up to 2.1 Mb of so far undescribed genomic content. Among these, 64% are considered ancestral to humans since they are found in non-human primate genomes. Furthermore, 37% of the NUIs can be found in the human transcriptome and 14% likely arose from Alu-recombination-mediated deletion. Our results underline the need of a set of human reference genomes that includes a comprehensive list of alternative haplotypes to depict the complete spectrum of genetic diversity across populations

Mechanistic studies on photochemical reactions of metal carbon bonds with oxygen

The selective oxidation of alkanes has been investigated using three different approaches; namely heterogeneous, biomimetic and homogenous catalytic oxidations. Chapter 1 focuses on the selective oxidation of alkanes using homogenous transition metal catalysts. The first example was reported in the early 1970s, which is known as the Shilov system. Several drawbacks to this classic reaction include poor selectivity and the use of an expensive oxidant source. Therefore, alternative metal catalysts and oxidants have been developed to study the selective oxidation of alkanes. This thesis focuses on using oxygen as the oxidant and late transition metals, in particular platinum or palladium, as the metal catalyst. The reactivity of a range of novel platinum and palladium alkyl or aryl complexes with oxygen are discussed. Chapter 2 describes the synthesis of cationic palladium(II) chloro and palladium(II) methyl complexes bearing 6,6”-dimethylterpyridine ligand (dmterpy). The methyl substituents on the ligand are sterically bulky, which cause one arm of the ligand to flip away from the metal centre of [PdCl(dmterpy)]Cl (2.26a and 2.26b). Similar behaviour involving [PdMe(dmterpy)]SbF6 (2.25) was observed in acetone, but the complex is stable in acetonitrile and shows reactivity with oxygen. Chapter 3 focuses on the synthesis of a series of neutral platinum(II) and palladium(II) alkyl or aryl complexes containing the 1,3-bis(2-pyridylimino)isoindole (BPI) ligand. The structure of some of these complexes were characterised by X-ray crystallography. Chapter 4 illustrates the reactivity of oxygen with these neutral platinum(II) and palladium(II) alkyl or aryl complexes bearing BPI ligands in various chlorinated and non-chlorinated solvents. These oxygen insertion reactions were monitored upon UV light exposure and in the dark. The reaction time of [Pt(BPI)Me] (3.31), [Pd(BPI)Me] (3.32), [Pt(BPI)Et] (3.37) and [Pt(BPI)Ph] (3.38) with oxygen is fastest in chloroform. The chloro complex [M(BPI)Cl] (3.14 when M = Pt(II); 3.43 when M = Pd(II)) was formed whenever chlorinated solvents were used. The mechanistic studies on the reactions between these platinum(II) and palladium(II) alkyl complexes and chloroform was investigated. The studies carried out in this Chapter also showed that radicals and singlet oxygen are unlikely to be involved in oxygen insertion reactions. The decomposition of these neutral platinum(II) and palladium(II) alkylperoxo complexes were investigated in Chapter 5. The methylperoxo complex [M(BPI)OOMe] (4.18 when M = Pt(II); 4.20 when M = Pd(II)) is unstable and dissociates to methanol and formaldehyde. These compounds react further with the solvent or water to give a mixture of side products. Similarly, the ethylperoxo complex [Pt(BPI)OOEt] (4.24) decomposes to ethanol and acetaldehyde. In addition, deuterium labelling studies was carried out to understand the fate of the methyl ligands in [Pt(BPI)CD3] (5.8). Studies carried out here also showed that methylperoxo ligand exchange occurs between [Pt(BPI)CD3] (5.8) and [Pd(BPI)CH3] (3.32) upon exposure to UV light in the presence of oxygen. Finally, the oxygen insertion reaction involving [Pt(BPI)Me] (3.31) and [Pd(BPI)Me] (3.32) complexes were studied by in-situ NMR spectroscopy.Open Acces

Efficient Inexact Proximal Gradient Algorithm for Nonconvex Problems

The proximal gradient algorithm has been popularly used for convex optimization. Recently, it has also been extended for nonconvex problems, and the current state-of-the-art is the nonmonotone accelerated proximal gradient algorithm. However, it typically requires two exact proximal steps in each iteration, and can be inefficient when the proximal step is expensive. In this paper, we propose an efficient proximal gradient algorithm that requires only one inexact (and thus less expensive) proximal step in each iteration. Convergence to a critical point %of the nonconvex problem is still guaranteed and has a $O(1/k)$ convergence rate, which is the best rate for nonconvex problems with first-order methods. Experiments on a number of problems demonstrate that the proposed algorithm has comparable performance as the state-of-the-art, but is much faster

Competitive Cloud Resource Procurements via Cloud Brokerage

In current IaaS cloud markets, tenant consumers non-cooperatively compete for cloud resources via demand quantities, and the service quality is offered in a best effort manner. To better exploit tenant demand correlation, cloud brokerage services provide cloud resource multiplexing so as to earn profits by receiving volume discounts from cloud providers. A fundamental but daunting problem facing a tenant consumer is competitive resource procurements via cloud brokerage. In this paper, we investigate this problem via non-cooperative game modeling. In the static game, to maximize the experienced surplus, tenants judiciously select optimal demand responses given pricing strategies of cloud brokers and complete information of the other tenants' demands. We also derive Nash equilibrium of the non-cooperative game for competitive resource procurements. Performance evaluation on Nash equilibrium reveals insightful observations for both theoretical analysis and practical cloud resource procurements scheme design.published_or_final_versio

The use of feedback in training American listeners to perceive Cantonese tones

Thesis (B.Sc)--University of Hong Kong, 2008.Includes bibliographical references (leaves 29-30).Also available in print.A dissertation submitted in partial fulfilment of the requirements for the Bachelor of Science (Speech and Hearing Sciences), The University of Hong Kong, June 30, 2008.published_or_final_versionSpeech and Hearing SciencesBachelorBachelor of Science in Speech and Hearing Science

A Study of Competitive Cloud Resource Pricing under a Smart Grid Environment

In the current IaaS cloud market, to achieve profit maximization, multiple cloud providers compete non-cooperatively by offering diverse price rates. At the same time, tenant consumers judiciously adjust demands accordingly, which in turn affects cloud resource prices. In this paper, we tackle this fundamental but daunting cloud price competition problem with Bertrand game modeling, and propose a dynamic game to achieve Nash equilibrium in a distributed manner. Specifically, we realistically consider spot electricity prices under a smart grid environment, and systematically investigate the impact of different system parameters such as network delay, renewable availability, and cloud resource substitutability. We also perform stability analysis to investigate the convergence of the proposed dynamic game to Nash equilibrium. Cooperation among cloud providers can achieve aggregate cloud profit maximization, but is subject to strategic manipulations. We then propose our Striker strategy to stimulate cooperation, the efficiency of which is validated by repeated game analysis. Our evaluation is augmented with realistic electricity prices in the spot energy market, and reveals insightful observations for both theoretic analysis and practical pricing scheme design.published_or_final_versio

The Politics of Indigenization: A Case Study of Development of Social Work in China

Internationalization and indigenization are dialectical processes of knowledge transfer. However, social work literature has paid scant attention to the process of indigenization, which can best be understood as one of recontextualization. This paper introduces Basil Bernstein\u27s theory, which contends that recontextualization is a political process, as an analytical tool for us to understand the politics of indigenization. To demonstrate the usefulness of this tool, this paper analyzes how, in China, the Ministry of Civil Affairs and social work academics interactively compete for this control

Profiling buyers of green buildings

Thesis (B.Sc)--University of Hong Kong, 2009.Includes bibliographical references (p. 98-107).published_or_final_versio