Karst and cave development and groundwater resources of Dong Van Karst Plateau, Northern Vietnam

Karst regions are not only valuable in terms of landscape, tourism, and culture but also offer a variety of natural resources such as freshwater and biodiversity. In particular, groundwater from karst aquifers has proven to be the major freshwater source for drinking-water supply and agricultural irrigation in many countries and regions throughout the world. In tropical and subtropical areas, like in Southeast Asia, the special climate conditions with dry and humid-rainy seasons have created numerous typical tropical karst landforms, but also hamper a continuous freshwater supply. In highland districts of Ha Giang province which is located in the Northern part of Vietnam, although the total surface water discharge is high, the large variations in rainfall, as well as discharge between dry and wet seasons, result in seasonal water scarcity. Since 2010, when Dong Van Karst Plateau was designed as a UNESCO Global Geopark, regional economic development, the number of visitors has strongly increased which has positively contributed to changing the lives of the local people, but also enhances the pressure on the already tensed water supply situation. In order to overcome this issue, plenty of solutions have been applied to address water scarcity in the dry season, but this is not effective or sustainable due to high costs, easy damage, and easily polluted water sources. Therefore, adapted water supply strategies such as the KaWaTech project model has developed and implemented to meet the increasing water demand. However, these areas belong to the small catchment which is located in the northeastern part of the geopark and consist of favorable geological conditions for groundwater availability. Meanwhile, the karst plateau south of Dong Van town is still facing serious water scarcity. In this context, studying and understanding the processes that take place in the Dong Van karst systems is a key basis for developing adequate solutions for the protection, management and sustainable use. Extensive field studies combined with analysis of the huge cave survey database was carried out and resulted in a karstification model which is presented in Chapter 2 of this thesis. Accordingly, the cave classification based on the cave conduit\u27s geometric parameters indicated that the karst evolution in Dong Van Karst Plateau is in a youthful stage, with cave systems developed mainly of the isometric form (developed almost vertically) in the vadose zone, and not yet deepened to the local base level. The development of horizontal cave passages is related to two levels of planation surfaces at 1000-1250 and 1250-1450 masl. Meanwhile, at an altitude of 240 masl, the Na Luong cave which belongs to the Na De spring system could be the local base level for karst erosion. Additionally, cave passage orientation shows that the cave system formed and developed under the influence of tectonic activities in the Cenozoic. The second study of this thesis (Chapter 3) focuses on the approach of using concentrations of major ions, trace and rare earth elements to clarify chemical signatures, and the ability for connections among sampling areas in the study area. To this end, a combination of different methods was applied, including mapping, hydrochemical analyses, using trace elements as the natural tracers, and multivariate statistical. It results in a basic hydrogeologic conceptual model for the Dong Van karst aquifer system. Accordingly, the Na De spring system and Na Luong cave are identified as belonging to the same discharge zone of Bac Son Carboniferous karst aquifer, while the southwestern springs and Tia Sang cave were identified as typical of shallow groundwater movement in the weathered surface zone in non-karst formations. In addition, it is possible to show a connection between the mining area and Na Luong cave by the abnormally high arsenic concentrations combined with location and geologic data. Meanwhile, Hang Rong cave has the features of a carbonate reservoir that developed in Triassic siliceous limestones of the Hong Ngai Formation, but is mainly associated with the Bac Son karst aquifer. Notwithstanding the significant differences in the water-chemistry signatures, the commonalities in REE distribution patterns between Tia Sang cave and the Na De spring system, combined with geologic data, lead to speculation that it could be one of the recharge sources of the Na De discharge zone. The results presented in this thesis have essentially clarified the development of karst and caves, as well as the hydrogeochemical processes and connectivity ability of karst aquifers on the Dong Van Karst Plateau. Although there are still some incompletions, the results obtained are rather positive, which provides the basis for future detailed hydrogeologic studies in this area

Employee Volunteer Program in the Eyes of College Students

The purpose of this study is to understand University of New Hampshire (UNH) students’ opinions about Employee Volunteer Program (EVP), especially what value they place upon EVP and what they are looking for in an ideal EVP. Based on the background and context of EVP among Millennials recently, the paper raises questions about EVP’s value to students generally and how factors like past volunteering experience, gender, and occupation/majors impact students’ valuation of EVP. Data collected from this research leads to several conclusions. Although many students do not fully understand EVP, most of them have positive opinions of the program, leaving great potential for employers’ education and recruiting messages transmission. It also suggests some potential areas for further study and recommendations to employers regarding EVP as a tool to attract top talent and keep employees engaged

Argument-based validation of a high-stakes Listening test in Vietnam

More than a decade ago, the Vietnamese Government announced an educational reform to enhance the quality of English language education in the country. An important aspect of this reform is the introduction of the localized test of English proficiency which covers four language skills, namely listening, speaking, reading, and writing. This high-stakes English test is developed and administered by only a limited number of institutions in Vietnam. Although the validity of the test is a considerable concern for test-takers and test score users, it has remained an under-researched area. This study aims to partly address the issue by validating a listening test developed by one of the authorized institutions in Vietnam. In this thesis, the test is referred to as the Locally Created Listening Test or the LCLT. Using the argument-based approach to validation (Kane, 1992, 2013; Chapelle, 2008), this research aims to develop a validity argument for the evaluation, generalization and explanation inferences of the LCLT. Three studies were carried out to elicit evidence to support these inferences. The first study investigated the statistical characteristics of the LCLT test scores, focusing on the evaluation and generalization inference. The second study shed light on the extent to which test items engaged the target construct. The third study examined whether test-takers’ scores on the LCLT correlated well with their scores on an international English test that measured a similar construct. Both the second and third study were carried out to support the explanation inference. These three studies did not provide enough evidence to successfully support the validity argument for the LCLT. The test was found to have major flaws that affected the validity of score interpretations. In light of the research findings, suggestions were given for the betterment of future LCLTs. At the same time, this research helped to uncover the impacts of certain text and task-related factors on the test-takers’ performance. Such insights led to practical implications for the assessment of second language listening in general. The results of this research also contributed to the theory and practice of test localization, a relatively new paradigm in language testing and assessment

Use of major ion chemistry and trace and rare earth elements to characterize hydraulic relations, mixing processes and water–rock interaction in the Dong Van karst aquifer system, Northern Vietnam

The effectiveness of using a groundwater geochemistry approach in karst hydrogeologic research is highlighted. In particular, this approach is useful for preliminary investigations, such as for the study described here on the Dong Van karst aquifer system in Northern Vietnam. Analyses of different groundwater chemistry parameters complement each other, to clarify hydrochemical processes that are occurring in the karst system. The results of this study show that major ion composition can be used to clarify water chemistry signatures, as well as to identify the mixing processes and water–rock interactions in aquifers. Meanwhile, trace element concentrations and rare earth element patterns can be used as potential natural tracers when some processes are not revealed through conventional hydrochemical methods. These natural tracers can also be used to identify contaminant sources and/or contaminant transport pathways in karst aquifers. Viewed holistically, the groundwater geochemistry approach provides scientific information to establish a basic hydrogeological conceptual model and to estimate the water balance, which has implications for water resources protection and management in karstic systems

Further Discussion On Applying Case Study Method In Investment Law Course – A Case Of Education Investment In Vietnam

Purpose: The aim of this study is to focus on clarifying using case study method to improve taching law course. Currently, many universities around the world are applying a new teaching method. It can help students absorb knowledge more efficiently and faster. That is the case study. Using a Case Study allows a deeper understanding of cases as a unit, through comparing the similarities and differences of individual cases. Design/methodology/approach: The study uses qualitative analysis, synthesis and inductive methods, together with studies and references from CPTPP, FTA Agreement, as well as Regulations on assurance of business investment activities. Findings: The application of this method to teaching helps learners to approach very applicable situations. The situations or problems close to the theory will also help them to systematize all the knowledge they have learned to apply to solve the assigned problem. Not only use the knowledge learned, but also learn related knowledge outside the program to solve the problem. Case Study is an extremely interesting and interesting learning method, helping us to associate reality and apply it to solve problems and help us remember longer. If you really understand what a case study is, then apply it to your life and work. The results show the regulations on guaranteeing ownership rights as well as ensuring investors' business investment activities have been clearly stipulated in the 2020 Labor Law of Vietnam. These regulations have concretized the constitutional principle of investors' freedom to invest and do business in industries that are not prohibited by la

Hierarchical robust fuzzy sliding mode control for a class of simo under-actuated systems with mismatched uncertainties

The development of the algorithms for single input multi output (SIMO) under-actuated systems with mismatched uncertainties is important. Hierarchical sliding-mode controller (HSMC) has been successfully employed to control SIMO under-actuated systems with mismatched uncertainties in a hierarchical manner with the use of sliding mode control. However, in such a control scheme, the chattering phenomenon is its main disadvantage. To overcome the above disadvantage, in this paper, a new compound control scheme is proposed for SIMO under-actuated based on HSMC and fuzzy logic control (FLC). By using the HSMC approach, a sliding control law is derived so as to guarantee the stability and robustness under various environments. The FLC as the second controller completely removes the chattering signal caused by the sign function in the sliding control law. The results are verified through theoretical proof and simulation software of MATLAB through two systems Pendubot and series double inverted pendulum

Quasi-Brittle Self-Healing Materials: Numerical Modelling and Applications in Civil Engineering.

Ph.DDOCTOR OF PHILOSOPH

Biochemical Basis of Autoactivity of a Pair of Plant NLR Immune Receptors

An immune system enables organisms to defend themselves against a myriad of pathogens and diseases. Plants, which can rely only on innate immunity, have evolved different types of receptors to detect pathogens. Transmembrane receptors can recognize pathogenic conserved structures called pathogen- associated molecular patterns (PAMPs) such as flagellin, leading to PAMP-triggered immunity (PTI). Intracellular receptors recognize specific molecules delivered by pathogens into plant cells, known as effectors, and activate effector-triggered immunity (ETI) when PTI is overcome. Most of the ETI-mediating intracellular receptors belong to the NLR protein family characterized by a nucleotide-binding domain and leucine-rich repeats. NLRs perceive matching effectors, through either physical binding to the effector (direct recognition) or by sensing effector-induced biochemical modifications of a host target (indirect recognition). NLR-dependent signaling often leads to a hypersensitive response (HR), featured by localized cell death at the site of the infection, which stops pathogen spread and disease development. Mis-regulation of NLRs in the absence of pathogens can lead to inappropriate responses of the immune system, known as autoimmunity, causing spontaneous cell death, necrotic lesions and developmental defects. Autoimmunity can occasionally be observed in hybrid plants. This type of hybrid weakness can result from deleterious epistatic interactions between NLR genes from the two parents. In this thesis, I investigated the biochemical mechanism of autoimmunity in hybrids of two natural Arabidopsis thaliana accessions from Umkirch (Southwestern Germany). The two causal genes involved, DM1 (DANGEROUS MIX 1) from Uk-3 and DM2 from Uk-1, both encode NLRs. The causal DM2 variant is located in a multi-gene cluster with diverse NLR members, while DM1 is a single-gene NLR locus. In this study,I showed that signaling mediated by DM1 and DM2 uses the same pathway that other plant NLRs deploy upon non-self recognition. Cell death signaling induced by DM1 and DM2 involves heteromeric association of both proteins through their N-terminal regions including TIR domains, with DM1 forming inactive homo-oligomers in the absence of DM2. Mutations in the P-loop of either DM1 or DM2 suppressed HR, indicating the 1 contribution of both proteins to signaling. The contributions of the two NLRs to downstream signaling are, however, not symmetrical. Mutations in an NLR signature motif that are likely to affect conformation around the ATP binding pocket greatly change the activity of only DM2. Taken together, my results suggest that DM1 acts primarily as a signal transducer, and DM2 as a signal trigger. Autoimmunity triggered by joint action of this NLR pair thus suggests that the activity of the signaling complex depends on the sum of the complementary activities of the partner NLRs. Knowledge of the biochemical basis of autoactivity induced by plant NLR pairs will help us to understand how plant autoimmunity arises through NLR interaction, and how NLR activity is regulated to avoid inappropriate activation to minimize the plant fitness cost in the absence of pathogens

SOCIAL SECURITY CONTRIBUTION INDEBTED FIRMS IN VIETNAM: CHARACTERISTICS AND MARKET VALUE

Abstract: This research is the first to empirically analyse the characteristics of firms that defer the social security contribution for their employees to the Vietnam Social Security agency, which is a chargeable offense starting 2018 as the Vietnam government focuses on ensuring worker welfare. Using data on 873 public firms headquartered in four major cities (Ha Noi, Ho Chi Minh, Da Nang, and Hai Phong), we find that non-state-owned firms and firms with lower profitability and higher debts are more likely to be in arrears on social security contribution. On the other hand, the roles of foreign ownership, size, number of employees, and number of branches/offices are insignificant. We further show that being social security contribution indebted would negatively affect shareholders’ interest as it is associated with lower firm market values.Key words: social security contribution, worker welfare, state ownership, foreign ownership, firm market valu