Valuation Semigroups of Two Dimensional Local Rings

We consider the question of when a semigroup is the semigroup of a valuation dominating a two dimensional noetherian local domain, giving some surprising examples. We give a necessary and sufficient condition for the pair of a semigroup S and a field extension L/k to be the semigroup and residue field of a valaution dominating a regular local ring R of dimension two with residue field k, generalizing the theorem of Spivakovsky for the case when there is no residue field extension.Comment: 34 pages. Final versio

Efficient Inversion of Multiple-Scattering Model for Optical Diffraction Tomography

Optical diffraction tomography relies on solving an inverse scattering problem governed by the wave equation. Classical reconstruction algorithms are based on linear approximations of the forward model (Born or Rytov), which limits their applicability to thin samples with low refractive-index contrasts. More recent works have shown the benefit of adopting nonlinear models. They account for multiple scattering and reflections, improving the quality of reconstruction. To reduce the complexity and memory requirements of these methods, we derive an explicit formula for the Jacobian matrix of the nonlinear Lippmann-Schwinger model which lends itself to an efficient evaluation of the gradient of the data- fidelity term. This allows us to deploy efficient methods to solve the corresponding inverse problem subject to sparsity constraints

Impacts of the global economic crisis on foreign trade in lower-income economies in the Greater Mekong Sub-region and policy responses: the case of Vietnam and its implications for Lao PDR and Cambodia

This research seeks to better understand the impacts of the global economic crisis on Vietnam’s foreign trade and policy responses, and from this, draw inferences for Lao PDR and Cambodia.Global economic crisis, lower-income economices, GMS, CLMV

The Hallyu influences on travel motivation to Korea of Vietnamese Millennials and Generation Z: A case study on Korean dramas and movies

Growth of affordable tourism and expansion of Korean pop-culture, also known as Korean wave or Hallyu, are seen as factors that especially impact consumer habits of Millennials and Generation Z. This dissertation analyses the broad term of film-induced tourism with a specific case study of Korean dramas and movies as an influential factor motivating travel among Vietnamese young adults classified as Millennials and Generation Z. The analysis describes psychological factors, precisely travel motivation shaping decision-making process in tourism, and phenomenon of film-induced tourism. Thesis posed by this dissertation is supported by a practical exercise realized as a survey with a questionnaire designed as a set of nominal and 5-point Likert scale questions. Results of the survey are analyzed and discussed in detail. The findings confirm a relationship between Korean dramas, movies and travel decision of Vietnamese young adults where Korean dramas and movies exert their influence mainly on shaping image of featured locations and promoting awareness of Korea as a tourism destination. The findings also reveal that a low correlation between the level of exposure and travel decision as well as a moderate correlation of the level of affinity with travel decision. Moreover, two new determinants have been extracted from ten motivational elements, namely intrinsic desire and extrinsic factor which are seen as the primary motives behind travel decision

The Relationship between Teachers\u27 Interaction Strategies and Student Oral Involvement

A lot of research has focused on exploring reasons for and solutions to Asian students’ reticence in speaking. It is found that their unwillingness to speak is affected not only by the students themselves but also by the situations they are placed in. However, there is still space to explore how teachers use interaction strategies to enhance students’ speaking involvement, especially in Vietnam. This paper examines the relationship between teacher interaction strategies and student oral involvement. The data were collected via audio-recording and class observation. Five experienced teachers and their respective classes at a center for foreign languages were invited to participate in the study. The data were analyzed qualitatively based on the three interaction strategies proposed by Lee and Ng (2010). The findings show that three types of interaction strategies were used by the teachers in the classroom and had a positive effect on student oral involvement. The extent to which students are involved orally in response to these strategies was discrepant. More importantly, there are others elements related to pedagogical factors such as lesson objectives, task type, activities used, classroom management and the proficiency level of the students which were also identified to impact a teacher’s interaction strategy decision making