Molecular Kondo effect in flat-band lattices

The Kondo effect of a single magnetic impurity embedded in the Lieb lattice is studied by the numerical renormalization group. When the band flatness is present in the local density of states, it quenches the participation of all dispersive electrons in the Kondo singlet formation, and reduces the many-body Kondo problem to a two-electron molecular Kondo problem. The two-electron analog of the many-body Kondo singlet, a quantum entanglement of two spins, is stable at low temperature, and the impurity contributions to thermodynamical and dynamical quantities are qualitatively different from that obtained in the conventional Kondo effect in systems without flat bands. The existence conditions of the molecular Kondo effect in narrow band systems are also discussed

INVESTIGATING EFL TEACHERS’ PERCEPTIONS OF IMPLEMENTING ACTIVE LEARNING TECHNIQUES IN TEACHING SPEAKING

Active learning (AL) is widely implemented in Asia including Vietnam. However, to date, research on this method seems to be scarce, particularly in the context of Vietnam. This study aims to investigate teachers' perceptions of AL and its principles in teaching English speaking. In addition, the study also explores teachers’ attitudes about AL implementation and their concerns about applying this method to their teaching context. Ten teachers of English teaching at a university in the Mekong Delta, South of Vietnam participated in the study. A semi-structured interview activity was employed to collect data. The results showed that the teachers generally had a high level of understanding of AL teaching principles and showed positive attitudes toward the implementation of it. The results also revealed teachers’ concerns about implementing AL. In particular, three problems of large class size, students’ mixed language proficiency and time limitation were addressed. Accordingly, possible suggestions for a better implementation of AL in teaching English speaking in Vietnam and similar contexts elsewhere will be provided.  Article visualizations

A novel autonomous wireless sensor node for IoT applications

A novel wireless sensor network node (WSNN) is presented in this paper where the solar energy harvester system is used as an autonomous power solution for endless battery lifetime. In this sensor node, the meander-line Inverted-F-Antenna (MIFA) is proposed and integrated in a single -CC2650 chip of Texas Instrument. The simple structure, low cost, compact size, high efficiency and low power consumption are advantages of this single-chip WSNN. The experimental results show that MIFA antenna is promising solution to enhance communication performance in WSN. In addition, the investigated single-chip WSNN with multi-wireless technologies including Bluetooth Low Energy and Zigbee as well as 6LowPAN is an attractive device for internet of thing (IoT) applications

Effects of Mannan Oligosaccharide (MOS) on the Survival, Physiological, and Immunological Response of the Black Tiger Prawn (Penaeus monodon Fabricius, 1798) when Challenged with two Different Stressors

Two trials were conducted to determine the effects of mannan oligosaccharide (MOS) on the resistance of the black tiger prawn (Penaeus monodon) to two different stressors, bacterial infection by Vibrio alginolyticus, and the environmental pollutant ammonia (NH3). Prawns were fed two different diets, 0% (control diet) and 0.15% MOS, for 8 weeks prior to exposure to the stressors. They were then tested for survival, physiological, and immunological parameters, as indicators of health status. When the two groups were exposed to NH3 and bacterial infection, survival of prawns fed the MOS diet was significantly higher (P<0.05) than prawns fed the control diet. Similarly, the wet hepatosomatic index (Hiw), dry hepatosomatic index (Hid), hepatopancreatic moisture content (HM), total hemocyte count (THC), and granular cell percentage (GC%), of the MOS fed prawns was significantly higher (P<0.05) than in prawns fed the control diet. Bacteremia of the MOS fed prawns was lower (P<0.05) than the control diet-fed prawns after bacterial infection. Findings demonstrated the potential of MOS to improve the survival, health status, and immunity of black tiger prawns when challenged with bacterial infection and NH3 exposure

Acquisition of request modifiers in Vietnamese as a second language

This study examines the acquisition of request modifiers by learners of L2 Vietnamese, with a view to expanding the range of target languages under inquiry and contributing to the field of L2 pragmatics acquisition. Data were collected from nine Vietnamese native speakers and 18 learners from various language backgrounds, using open role-plays in six scenarios with differing social power and imposition levels. An analysis was made of the learners' use of request modifiers in relation to their proficiency levels in Vietnamese and their lengths of residency in the target language environment. Findings supported claims in the literature that learning pragmatics is particularly challenging for low-proficiency learners, and provided some evidence of pragmatic development in the case of highproficiency learners who had stayed in the target language culture for an extended period

THE RELATIONSHIP BETWEEN LEARNING STRATEGY USE IN ENGLISH AND MOTIVATION OF STUDENTS AT A COLLEAGUE IN CAN THO CITY, VIETNAM

Among the many factors that increase students’ achievement in the mastery of foreign languages, including English, are motivation and use of language learning strategies. Previous studies by a range of researchers have identified these two elements as the most important in obtaining success in language learning. This study carried out on 152 university students, roughly equal in gender, studying at a university in Can Tho, Vietnam, sought to discover the relationships between these two factors within the Vietnamese language learning context. In particular, the study sought to 1) discover which of two types of motivation, intrinsic and extrinsic, is most prevalent among the students studied; 2) their use of language learning strategies; 3) reveals the relationship between students' motivation and use of language learning strategies; and 4) describe the differences in their use of language learning strategies based on whether their motivation was high, medium or low. Research instruments included Schmidt et al.'s Questionnaire on Motivation in Learning English, and Oxford's Strategy Inventory for Language Learning (both modified for the Vietnamese language learning context and translated into Vietnamese), plus an interview with 18 of the students to gain greater insight into the answers they gave on the questionnaires. Results were obtained using standard deviations and t-tests. They showed that Vietnamese university students are mainly extrinsically motivated; that all strategies were used at least at a medium level, amidst other fluctuations; and that those metacognitive strategies are most prevalent among medium and high motivated students but affective strategies are most common among low motivation students. Recommendations flowing from these results are that teachers should prioritize the formal teaching of learning strategies and should attempt to increase intrinsic motivation by putting greater emphasis on making language learning fun and relevant to the students' interests and passions. Article visualizations

Online Load Balancing for Network Functions Virtualization

Network Functions Virtualization (NFV) aims to support service providers to deploy various services in a more agile and cost-effective way. However, the softwarization and cloudification of network functions can result in severe congestion and low network performance. In this paper, we propose a solution to address this issue. We analyze and solve the online load balancing problem using multipath routing in NFV to optimize network performance in response to the dynamic changes of user demands. In particular, we first formulate the optimization problem of load balancing as a mixed integer linear program for achieving the optimal solution. We then develop the ORBIT algorithm that solves the online load balancing problem. The performance guarantee of ORBIT is analytically proved in comparison with the optimal offline solution. The experiment results on real-world datasets show that ORBIT performs very well for distributing traffic of each service demand across multipaths without knowledge of future demands, especially under high-load conditions

INTEGRATION OF CROSS-CULTURAL EXPERIENCES AND PROFESSIONAL COMPETENCIES: VIEWS FROM INTERNATIONAL EXCHANGE PROGRAMS IN HIGHER EDUCATION

Encouraging hospitality students in reflective and transformative learning toward a global mindset becomes an imperative for developing their cross-culturally professional competency in preparation of the future career path development. Oversea exchange programs are among the initiatives to raise personal, professional and cultural awareness for the hospitality students in a pathway to encourage cross-cultural learning among students in similar fields. However, to what extent the development of a global mindset gained from the cross-cultural experiences could help undergraduate hospitality students gain their professional competency in terms of cultural skills in the hospitality and tourism context is the main issue to be described by this study. Content analysis has been conducted on in-depth interview data given by hospitality oversea exchange students who are both current students and graduated ones. The most popular modes of international student exchanges such as team project, assignment, presentations, and travel exchanges are taken into consideration to highlight deeper insights into a mutual interest between the cross-cultural experiences and the professional competency related cultural skills. The study reveals that cultural understanding needs to be experienced in the real setting context. Furthermore, we also discovered that cultural exchange outcomes are normally obtained in the daily informal practices instead of formal studies. However, the current study is constrained within few selected countries where students have been experienced and the current partnership between the home and host Institutions. This paper provides actionable guidelines and approach for integrating the critical component of cultural exchange program in the traditional curriculum program of hospitality

Impact of foaming conditions on quality for foam-mat drying of Butterfly pea flower by multiple regression analysis

In recent years, the Butterfly pea flower has been increasingly interested in its color and function. However, the preservation of the extract faced many difficulties; therefore, foam drying technology was applied to solve this problem. The study was conducted to determine the effect of foaming conditions, including albumin ratio, carboxymethyl cellulose (CMC) ratio, and whipping time on foam characteristics. At the same time, the multi-dimensional regression method was also used to determine the most suitable foaming conditions for the following process. The research results showed that all 3 factors strongly influenced the foaming process of pea flower extract. It could be concluded that the most suitable condition for foaming is to use 9.3% albumin, 0.79% CMC and stir for 19 min. Under these conditions, the foam expansion and stability were 584.79% and 96.44% respectively. The powder obtained from the foam drying of Butterfly pea flower extract was also analyzed for quality. The temperature of 65 oC for 4 hrs gave relatively high-quality powder with protein content, anthocyanin and antioxidant activity of 9.89 g/100g, 1.15 mg/g and 87.34% respectively. In conclusion, the foam-mat dried powder from butterfly pea flower extract is suitable for other processing processes, especially in the processing of folk cakes, pasta and bread industry

Evaluation of water loss and solute uptake during osmotic treatment of white radishes (Raphanus sativus L.) in salt-sucrose solution

White radish, scientifically known as Raphanus sativus L., is a yearly vegetable. Currently, it was being grown and widely used in the world, including Vietnam. These plants have been used as food or food processing. The osmotic treatment of vegetables involves the removal of water from plants in which the solids from the osmotic solution are transported to the plant material by osmosis. By this procedure, sucrose and saline solution are usually performed. White radishes were dehydrated in different hypertonic solutions by combined sucrose and NaCl at three different concentrations, including 9 runs. Mass transfer behaviour was applied according to three common models such as Fick’s second law, Weibull and Peleg’s equations based on the change of moisture and solid content of white radish during osmotic dehydration. The obtained results showed that the mass transfer was fast at initial stage and became slowly at the later stage. The effective moisture (Dm) and solid diffusivities (Ds) were ranged from 1.0186 to 1.2826x10-8 and from 1.0692 to 2.3322x10-8 (m2/s) respectively. The Peleg’s equation was found to be the best fitting for water loss and solid uptake thanks to the high determination coefficient (&gt;97.64%) and the low average relative error (&lt;3.174%). Raised up solution concentration resulted in higher water loss and mass gain