Ramsey numbers for set-colorings

For s, t, n ∈ N with s ≥ t, an (s, t)-coloring of K$_n$ is an edge coloring of Kn in which each edge is assigned a set of t colors from {1, . . . , s}. For k ∈ N, a monochromatic K$_k$ is a set of k vertices S such that for some color i ∈ [s], i ∈ c(uv) for all distinct u, v ∈ S. As in the case of the classical Ramsey number, we are interested in the least positive integer n = R$_{s,t}$(k) such that for any (s, t)-coloring of K$_n$, there exists a monochromatic K$_k$. We estimate upper and lower bounds for general cases and calculate close bounds for some small cases of R$_{s,t}$(k)

Leprosy, impurity, and stigma in Vietnam

This Position Piece examines the nature of Vietnamese folk constructions of leprosy through Mary Douglas’s (1969) and Victor Turner’s (1967) works. Investigating Vietnamese explanations for the origins of leprosy and its channels of transmissions, symptoms, and consequences, I argue that these accounts are rooted in narratives of transition, transgression, the crossing of boundaries, and categorical confusion of various kinds. I argue that these deeply embedded perceptions of leprosy help to explain the existence of persistent stigma against leprosy in Vietnam, despite highly effective drug treatments and extensive state awareness programmes

Policy of mobilizing financial resources for developing new countryside in Vietnam

Financial resources and the institutional framework, as well as policies for mobilizing financial resources, are important issues that need to be addressed in the construction of new countryside in Vietnam. Financial resources for the new countryside mainly come from the state budget, credit sources, investments from enterprises, contributions, and support from organizations, individuals, and the local community. In recent years, the state has paid attention to financial investment and issued policies to mobilize financial resources for the new countryside. Through these policies, Vietnam's rural areas have achieved important results, with rural areas being renewed, the economy being developed, and the living standards of the people being improved. However, statistical analysis and research results show that, alongside the achievements, financial resources for new countryside have not yet satisfied the needs, and the policies for mobilizing resources are sluggish to innovate and have neither fully exploited the potential of rural areas nor effectively mobilized resources from the state and society. The state budget resources for investing in the new countryside are limited, and the investment resources from enterprises have yielded low results. Contributions from the people and the local community are voluntary and have not become the main resources mobilized for the new countryside. Based on the research results, the author proposes some solutions to improve the policies for mobilizing financial resources for the new countryside in Vietnam

Factors Affecting Responsibility Accounting: Evidence from Vietnamese Manufacturing Enterprises

Purpose: This study aims to examine (i) the number of product lines and steps in the manufacturing process affect the responsibility cost center in a responsibility accounting system (ii) the level of technology application, the qualification of managers at all levels affect the budgetary control system integrated to the responsibility accounting system in Vietnamese manufacturing enterprises.   Theoretical framework: The research identifies and examined the impacts of the number of product lines, the number of steps in the manufacturing process on the number of responsibility cost centers, and the impacts of the level of technology application, the qualification of managers at all levels on the budgetary control system to contribute the responsibility accounting system theory.   Design/methodology/approach:  A quantitative approach was applied with a sample of 108 Vietnamese manufacturing enterprises that is listed on the Vietnamese financial securities markets in 2020. OLS regression is applied to give a further analysis.   Findings: The regression findings support the significant positive impacts of the number of product lines and the number of steps in the manufacturing process on the number of cost centers as well as the significant positive correlation between the level of technology application and the effective budgetary control system, however, the effect of the qualification of managers at all levels is insignificant.   Research, Practical & Social implications: This study provides factors impacting the number of cost centers and the budgetary control system. The results of this study support the contingency theory.   Originality/value: These findings can be useful for Vietnamese manufacturing enterprises to take measures to strengthen cost control through the responsibility accounting system, thereby improving business efficiency

VIETNAMESE HIGH SCHOOL EFL TEACHERS’ PERCEPTIONS TOWARD ONLINE TEACHING UNDER THE IMPACT OF COVID-19

The coronavirus disease case, commonly known as Covid-19, has spread internationally since March 2020. Approximately 100 countries, including Vietnam, closed their schools due to a public health emergency, according to UNESCO. Due to the circumstance, teachers were forced to convert from in-person instruction to online instruction. In the context of Covid-19, this study investigated how EFL high school instructors felt about online English language education. A descriptive design and a mixed-methods approach were utilized in this investigation. Six EFL high school teachers in the Mekong Delta were interviewed for this study to get their perspectives. The findings demonstrated that the participants' opinions on the usefulness and simplicity of online instruction during the Covid-19 epidemic were overwhelmingly positive. Despite the challenges they encountered when conducting their online classes, the teachers were able to show the proper attitude toward using technology to teach. The pedagogical implications of online teaching and learning are also meant to encourage the development of innovative teaching strategies in the setting of high schools in the Vietnamese Mekong Delta.  Article visualizations

THE INTERACTION BETWEEN SELF-REGULATED LEARNING STRATEGIES AND EFL TEENAGER LEARNERS’ POSTCARD WRITING AT ENGLISH CENTER IN MEKONG DELTA, VIETNAM

The current study aims at investigating the possible interaction of EFL teenage learners’ postcard writing performance (according to A2 level) and their self-regulated learning strategies at an English center. The research also helps to determine the level of interaction between EFL teenagers’ self-regulated learning (SRL) strategies and their postcard writing performance. Thus, it also examined the frequency of use of SRL strategies in writing among those learners. A total of 74 learners completed 32 items in the self-regulated learning strategies questionnaire including six dimensions of three categories namely environmental processes, behavioral processes, and personal processes. Then, three successful writers and three less successful writers were invited into the semi-structured interview. The findings indicated that SRL strategies had a positive impact on EFL teenage learners' postcard writing. The more SRL strategies used in writing, the higher the learners' score. Among these strategies, environmental factors may have a stronger influence than behavioral or personal factors. Specifically, environmental structuring and help-seeking strategies are most frequently used. The findings also showed that EFL teenage learners use SRL strategies to a moderate degree when given writing tasks. Besides, the results of the interview reveal that successful learners self-regulated better than less successful ones. They also self-evaluated their writing more frequently than those who are less successful. Based on the findings of this study, pedagogical implications and recommendations for further study are presented.  Article visualizations

LEAF LITTER FUNGI ISOLATED IN BACH MA NATIONAL PARK, VIET NAM

A survey of fungi from leaf litter at Bach Ma National Park in Viet Nam was initiated.  Using surface disinfection and moist chamber with single spore isolation methods, 102 isolates were obtained and of those, 70 isolates were selected for further morphological study. They belong to 5 classes, 9 orders, 14 families, 33 genera, and 51 species. Among them, Ceratosporella deviata, Lateriramulosa sp., Isthmolongispora ampuliformis, Polylobatispora quinquecornuta, Scolecobasidium tricladiatum, Triglyphiuma labamense, Tricladiella pulvialis, Tripospermum myrti, Triscelophorus sp., Varicosporium elodeaea are newly recorded in Viet Nam

Optimization of ultrasound-assisted extraction of phenolic compounds from fresh Moringa oleifera leaves with a response surface methodology and comparison with the Soxhlet extraction method

ABSTRACT. The present study evaluated the optimum conditions of ultrasound-assisted extraction (UAE) and Soxhlet extraction (SE) of antioxidant capacities and total phenolics from fresh Moringa oleifera leaves, using the response surface methodology. Spectrophotometric method with Folin–Ciocalteu and 2,2-diphenyl-1-picrylhydrazyl (DPPH) reagents was used to determine the total phenolic content (TPC) and the antioxidant activity (AA), respectively. The four models obtained showed the non-linear and quadratic dependences of both measured responses (TPC and AA) which were influenced significantly by all control variables including the acetone solvent (70%, v/v) to solid (SS) ratio, extraction time, and extraction temperature of both extraction methods. Furthermore, at the same extraction temperature, the extraction efficacy of UAE was better than SE as significantly shorter extraction time, less extraction solvent, but higher bio-active content was experienced. The optimal UAE conditions included a SS ratio of 31:1 (mL/g), extraction time of 26 min, and extraction temperature of 59 oC, resulting in the maximum TPC (34.36 mg GAE/g dry weight, DW) and AA (491.9 µmol TE/g DW) in the extracts. In addition, the models proposed were considered to be accurate and reliable for predicting the TPC and AA of fresh M. oleifera leaf extract. The research findings also imply potential applications for ultra-sonication extraction to produce the extracts from fresh M. oleifera leaves for pharmaceutical industry as well as food technology.   KEY WORDS: Antioxidant activity, Herbal plant, Model, Polyphenols, RSM   Bull. Chem. Soc. Ethiop. 2022, 36(2), 261-275.                                                                DOI: https://dx.doi.org/10.4314/bcse.v36i2.