Cohen-Macaulayness of monomial ideals and symbolic powers of Stanley-Reisner ideals

We present criteria for the Cohen-Macaulayness of a monomial ideal in terms of its primary decomposition. These criteria allow us to use tools of graph theory and of linear programming to study the Cohen-Macaulayness of monomial ideals which are intersections of prime ideal powers. We can characterize the Cohen-Macaulayness of the second symbolic power or of all symbolic powers of a Stanley-Reisner ideal in terms of the simplicial complex. These characterizations show that the simplicial complex must be very compact if some symbolic power is Cohen-Macaulay. In particular, all symbolic powers are Cohen-Macaulay if and only if the simplicial complex is a matroid complex. We also prove that the Cohen-Macaulayness can pass from a symbolic power to another symbolic powers in different ways.Comment: The published version of this paper contains a gap in the proofs of Theorem 2.5 and Theorem 3.5. This version corrects the proofs with almost the same arguments. Moreover, we have to modify the definition of tight complexes in Theorem 2.5. These changes don't affect other things in the published version. A corrigendum has been sent to the journa

Language learning strategies among Vietnamese EFL High School students

Despite productive research on language learning strategies (LLS), LLS is still a multifaceted topic subject to controversy. Thus, previous researchers have encouraged conducting further LLS research in different educational contexts and student population. The current study was conducted to examine the LLS use among high school students, a relatively neglected population in previous LLS studies. Participants in the study were 83 Vietnamese tenth-graders who were administered the Strategy Inventory for Language Learning (SILL) by Oxford (1990), including six subscales: memory-related, cognitive, compensatory, metacognitive, affective and social strategies. The results suggested that high school learners utilized a wide range of language learning strategies at a medium level of frequency, indicating a necessity for more explicit LLS instruction. While metacognitive strategies were reported as the most frequently utilized strategies, affective strategies were the least. Cognitive strategies, which were strongly related to other LLS groups, tended to play the central role in the language learners’ LLS employment. Gender was confirmed to be a significant factor that influenced the students’ LLS usage only in the case of social strategies. Pedagogical implications regarding strategy instruction were discussed

Language learning strategies among Vietnamese EFL High School students

Despite productive research on language learning strategies (LLS), LLS is still a multifaceted topic subject to controversy. Thus, previous researchers have encouraged conducting further LLS research in different educational contexts and student population. The current study was conducted to examine the LLS use among high school students, a relatively neglected population in previous LLS studies. Participants in the study were 83 Vietnamese tenth-graders who were administered the Strategy Inventory for Language Learning (SILL) by Oxford (1990), including six subscales: memory-related, cognitive, compensatory, metacognitive, affective and social strategies. The results suggested that high school learners utilized a wide range of language learning strategies at a medium level of frequency, indicating a necessity for more explicit LLS instruction. While metacognitive strategies were reported as the most frequently utilized strategies, affective strategies were the least. Cognitive strategies, which were strongly related to other LLS groups, tended to play the central role in the language learners’ LLS employment. Gender was confirmed to be a significant factor that influenced the students’ LLS usage only in the case of social strategies. Pedagogical implications regarding strategy instruction were discussed

Natural disaster, information technology, and agriculture production in Vietnam : evidence from panel data analysis

Agriculture is among the most susceptible industries to natural calamities. Technology is crucial to agricultural output. While agricultural machinery directly impacts agricultural output by increasing yield and quality, information technology may influence coping mechanisms for responding to natural disasters and so increase agricultural productivity. This paper examines (1) the degree to which agriculture production in Vietnam is impacted by natural disasters such as floods, drought, typhoons, and landslides, (2) how coping strategies mitigate the negative effects of natural disasters, and (3) how information technology influences the selection of coping strategies in response to a natural disaster. Our primary premise is that natural catastrophes have a detrimental influence on agricultural production and that coping mechanisms might somewhat mitigate these negative effects. In addition, information technology can facilitate the selection of coping measures for natural disasters.Khai Cong Dinh (School of Government, College of Economics, Law, and Government, University of Economics Ho Chi Minh City), Thanh Quang Ngo (School of Government, College of Economics, Law, and Government, University of Economics Ho Chi Minh City)Includes bibliographical references

Exposure to L2 online text on lexical and reading growth

With the fast-paced development of technology in today’s society, there has been emerging a shift from paper-based reading to digital online reading. While the benefits of exposure to print have been well-established in previous studies, how online reading may impact individuals’ literacy development is largely underexplored. The current study investigated if the amount of English reading experience on the Internet could predict EFL students’ lexical knowledge and reading comprehension ability. Participants were ninety-seven Vietnamese undergraduate students who were administered a website checklist and a vocabulary size test. Their reading comprehension scores were also collected as measures of their reading abilities. Descriptive statistics, hierarchical linear regression and structural equation modelling were utilized for data analysis. The results indicated that exposure to L2 online text was a significant predictor of the participants’ vocabulary size as well as their reading comprehension growth during a course of two years. Pedagogical implications are discussed

Criminal Justice Responses to Trafficking in Persons

Human trafficking is a domestic and transnational crime that poses complex law enforcement challenges to all nations. Vietnam is particularly affected due to rapid growth in labour migration and international tourism. The presumption of law makers is that by improving the criminal justice response to trafficking in persons (TIP), its incidence within the country and beyond its borders will decrease. Inherent in this premise is the assumption that strong legal sanctions deter would-be traffickers. This paper describes Vietnam’s criminal justice responses to human trafficking with reference to the legal framework and institutions. Barriers and challenges in implementing the ASEAN Convention on Trafficking in Persons (ACTIP), and the underlying reasons why the current response is inadequate in addressing TIP are identified with a focus on issues associated with victims and trials. The paper argues that Vietnam needs to increase efforts to meet its obligations and standards as set out in the United Nation’s Recommended Principles and Guideline on Human Rights and Human Trafficking and ACTIP. In particular, prosecution of traffickers and the protection of victims need to be prioritised.    Keywords: Human Trafficking, Human Rights, Labor Migration, Criminal Justice, Vietna

The Relation Between Environment and Psychological Development: Unpacking Vygotsky’s Influential Concept of Perezhivanie

In recent decades, Vygotsky’s sociocultural theory (VST) has become particularly influential in the fields of education and educational psychology. Perezhivanie is an important concept in VST that stipulates a relative influence of environment on a person’s psychological development depending on their age or stage of development. However, perezhivanie has been differentially interpreted and applied in previous literature to suit the purposes of domain-specific research. The lack of a comprehensive theoretical understanding of the concept can undermine research findings and their implications for educational practices. Drawing on a content analysis of Vygotsky’s key texts on perezhivanie, this paper provides a much-needed theoretical discussion that unpacks comprehensively the theoretical content of perezhivanie and the methodological principles guiding its application. The findings revealed that conceptually, perezhivanie can be defined as: (a) a theoretical relation between an individual and their environment, (b) an abstract experience of or attitude towards a life situation and (c) a concrete lived experience of an event within that situation. Four major discernible components of an individual’s perezhivanie include the environmental factor, personal characteristics mobilised, refraction prism and psychological influences. Five key methodological principles were conceived to assist the employment of perezhivanie in educational/psychological research: (1) utilising a perezhivanie as a unit of analysis, (2) analysing perezhivanie at different levels, (3) accounting for the perspective of the individual involved, (4) constructing the refraction prism and (5) determining the major personal characteristics mobilised in the perezhivanie. Implications for educational and research practices are then discussed

CFD results on hydrodynamic performances of a marine propeller

In this work, the commercial Computational Fluid Dynamics (CFD), ANSYS-Fluent V.14.5 has been used to illustrate the effects of rudder and blade pitch on hydrodynamic performances of a propeller. At first, the characteristic curves of a container ship propeller are computed. Then, effects of rudder on hydrodynamic performances of the propeller in the both cases of the propeller with and without rudder have been investigated. The relationships between the blade pitch angle and the hydrodynamic performances of the selected referent propeller in this work having designed conditions as diameter of 3.65 m; speed of 200 rpm; average pitch of 2.459 m and the boss ratio of 0.1730. Using CFD, the characteristic curves of the marine propeller, pressure distribution, velocity distribution around propeller and the efficiency of the propeller have been shown. From the obtained results, the effects of rudder and blade pitch angle on hydrodynamic performances of the propeller have been evaluated