Frequency-splitting Dynamic MRI Reconstruction using Multi-scale 3D Convolutional Sparse Coding and Automatic Parameter Selection

Department of Computer Science and EngineeringIn this thesis, we propose a novel image reconstruction algorithm using multi-scale 3D con- volutional sparse coding and a spectral decomposition technique for highly undersampled dy- namic Magnetic Resonance Imaging (MRI) data. The proposed method recovers high-frequency information using a shared 3D convolution-based dictionary built progressively during the re- construction process in an unsupervised manner, while low-frequency information is recovered using a total variation-based energy minimization method that leverages temporal coherence in dynamic MRI. Additionally, the proposed 3D dictionary is built across three different scales to more efficiently adapt to various feature sizes, and elastic net regularization is employed to promote a better approximation to the sparse input data. Furthermore, the computational com- plexity of each component in our iterative method is analyzed. We also propose an automatic parameter selection technique based on a genetic algorithm to find optimal parameters for our numerical solver which is a variant of the alternating direction method of multipliers (ADMM). We demonstrate the performance of our method by comparing it with state-of-the-art methods on 15 single-coil cardiac, 7 single-coil DCE, and a multi-coil brain MRI datasets at different sampling rates (12.5%, 25% and 50%). The results show that our method significantly outper- forms the other state-of-the-art methods in reconstruction quality with a comparable running time and is resilient to noise.ope

Outage performance analysis of non-orthogonal multiple access with time-switching energy harvesting

In recent years, although non-orthogonal multiple access (NOMA) has shown its potentials thanks to its ability to enhance the performance of future wireless communication networks, a number of issues emerge related to the improvement of NOMA systems. In this work, we consider a half-duplex (HD) relaying cooperative NOMA network using decode-and-forward (DF) transmission mode with energy harvesting (Ell) capacity, where we assume the NOMA destination (D) is able to receive two data symbols in two continuous time slots which leads to the higher transmission rate than traditional relaying networks. To analyse EH, we deploy time-switching (TS) architecture to comprehensively study the optimal transmission time and outage performance at D. In particular, we are going to obtain closed-form expressions for outage probability (OP) with optimal TS ratio for both data symbols with both exact and approximate forms. The given simulation results show that the placement of the relay (R) plays an important role in the system performance.Web of Science253918

STUDY ON ANTIBACTERIAL EFFECTS OF SEVERAL VIETNAMESE MEDICINE PLANTS AND THEIR RELATIONSHIPS WITH POLYPHENOL CONTENTS

Objective: Our study evaluated the inhibitory effects of 13 plant materials on bacterial growth, so as to explain their traditional uses in bacterial infections. In addition, the correlation between antibacterial effects of plants and the polyphenol contents or antioxidant activities was also verified to investigate if these properties were responsible for the plant antibacterial effects. Methods: We tested extracts with 20 bacterial strains purchased from Japan Veterinary Products Association (JVPA, Tokyo, Japan) and also the Escherichia coli (E. coli) and Streptococcus suis (S. suis) strains that we had previously isolated from livestock. After polyphenol contents and antioxidant activities were measured, we examined their correlations with antibacterial effects. Results: The results showed that all extracts exerted inhibitory effects on tested bacteria and at different levels. Among all of samples, betel and mother rhizome of turmeric showed the strongest effects and also exerted inhibition on antibiotic-resistant E. coli and S. suis bacteria. In addition, direct and significant correlations between antibacterial effects’ and polyphenol content’s values were established and thus demonstrating that antibacterial effects of plants were attributable, at least in part, to the presence of polyphenol compounds. Conclusions: Our study demonstrated the antibacterial effects of 13 plant materials and, therefore, partly gives pharmacological basis to explain their traditional uses in diseases associated with bacterial infections. In addition, as betel and mother rhizome of turmeric showed the highest effects, we suggested that they might serve as the most promissory candidates for bacterial treatment. However, follow-up researches are still required to assess their potentials

Policy research - implications of liberalisation of fish trade for developing countries. A case study of Vietnam

Since the end of the 1980s, when Viet Nam launched the doi moi policy of renovation, economic and social conditions have remarkably improved for the majority of the population. Poverty levels have been reduced by half over the past ten years. Social services have been improved and the economy in general continues to grow at a high rate. Vietnam is a country that has made significant strides in poverty reduction. Using the international poverty line, poverty incidence in Vietnam has been reduced from 37.4% in 1998 to 28.9% in 2002, or a 2% decline annually. Indicators such as access to basic services like electricity, clean water, health care and education show substantial improvement, especially in rural and remote mountainous areas. However, poverty still remains at a high level and the disparity among regions and ethnic groups is increasing. Poverty is still mainly concentrated in rural areas, where 90% of poor people live. In Vietnam the fisheries sector, especially coastal and inland aquaculture, is a prioritized sector for development. It is important not only for national income through exports but also as a subsistence activity for poverty reduction among the large rural population. Several million people depend on aquatic resources, directly or indirectly, for their livelihoods in inland and coastal areas. According to official employment statistics, one in every twenty-five persons in Vietnam is engaged in a fisheries activity. This means that there is a considerable labour force of around 3 million people is directly employed in the country’s fisheries sector. Farming of catfish is an important freshwater aquaculture activity in Vietnam, reared in floaing cases and ponds. “Tra” (Pangasius hypophthalmus1) and “basa” (Pangasius bocourti) farming is a traditional occupation and a means of livelihood for farmers in the Mekong Delta in the south of Vietnam (Trong et al, 2002). Thanks to the Government’s trade liberalization reforms catfish production increased substantially in recent years to catering to increased international demand and market opportunities. Volumes of cat fish fillet exported by Vietnamese export companies increased from 5,000 tonnes in 1996 to 10,000 tonnes in 2001 (90% of which was the tra species), with half exported to the United States

Job Creation in Hai Phong, Vietnam

A job is one of the basic needs of humans to ensure their life and comprehensive development. Job and job creation are listed as first priorities in sociodevelopment policies in Vietnam. Job policy, policies systems, and solutions to create jobs, develop a job market, and reduce jobless rates are the most basic policies of the nation. A job policy ensures that all persons who are capable of working will have the chance of a job and this will contribute to ensure the safety, stability, and development of society