Published: 2018-03-30

Monitoring population dynamics of the citrus pock caterpillar (Prays endocarpa) by sex pheromone traps in the Mekong Delta of Vietnam

Chau Nguyen Quoc Khanh, Pham Kim Son, Le Van Vang
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The citrus pock caterpillar (CPC), Prays endocarpa, is an important insect pest of “Nam roi” pomelo in the Mekong delta of Vietnam. In order to establish an efficient timing for a sustainable management program of CPC, monitoring the population dynamics and ratios of infected pomelo fruits at Binh Tan district, Vinh Long province had been conducted by use of sex pheromone traps and field investigation. The CPC adult flight and CPC larval infestation on pomelo fruits presented through out the year. However, high numbers of CPC captured males and ratios of larval infected fruits were observed in the dry season (from November to May) indicating the generation overlapping and negative effect of rainfall on the CPC population. Closely (Tightly) positive correlation between numbers of captured CPC males by pheromone traps and ratios of larval infected fruits with the correlation coefficient r of 0.77 (P = 0.00000364, one tailed probability or 0.00000727, two tailed probability); df = 23) and the regression equation of y = 0.3283x + 7.1766 revealed that numbers of males captured by sex pheromone traps were able to use for estimation of the action threshold for CPC.

Pathogenesis of infectious bronchitis virus (IBV) and laboratory test methods available to detect IBV in chickens

Tran Ngoc Bich, Nguyen Cam Loan, Nguyen Phuc Khanh
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Infectious bronchitis is a high contagious disease of chicken caused by gamma coronavirus. The disease was characterized by respiratory, renal, urogenital, and alimentary infections. Different strains of IBV may show variable tissue tropisms. For example, the classical strains of Massachussetts serotype (M41) targeted in respiratory and reproductive system while variant serotypes including QX, 793/B, D388 have been detected in respiratory, reproductive, alimentary system and kidney. Because the evolution and mutation of IBV have contributed to the emergence of new genotypes of IBV, the outbreak of IB still occurred in the vaccinated flocks. Therefore, diagnosis of IB plays an important role for limiting the effects caused by IBV infection. Available laboratory tests for diagnosis of IBV include virus isolation, electron microscope, immunohistochemistry, serological tests (virus neutralization, haemagglutination inhibition, enzyme-linked immunosorbent assay –ELISA-, agar gel immunodiffusion), genotype identification (RT-PCR, genome sequencing [using NGS Miseq]). 

Impact of managerial human resource quality on growth of firms in the Mekong Delta, Vietnam

Nguyen Pham Thanh Nam, Le Khuong Ninh
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This paper empirically examines the impact of managerial human resource quality on firm growth, using a primary data set of 450 firms randomly selected out of the Mekong River Delta (MRD), in addition to secondary data retrieved from relevant governmental organizations. The results found using OLS estimation method reveal those components of managerial human resource quality that do have effects on the growth of firms. Firstly, better professional knowledge enables managers to manage firms and make use of good market opportunities. Secondly, participation in short trainings will enrich knowledge for managers so as to create chances for firms to grow. Thirdly, experience is also a precious source to help managers avoid mistakes, which spurs faster firm growth. Fourthly, age has impact on firm growth. Both too young and too old managers have intrinsic weaknesses that hold back the possibility to grow of firms. Finally, overseas Chinese managers do better Vietnamese counterparts in terms of boosting the growth of firms thanks to certain specific attributes. Solutions are then proposed to upgrade managerial human resource quality so as to promote growth of firms in the MRD.

Using benthic diatoms as bio-indicators of water quality of the Saigon River, Vietnam

Pham Thanh Luu, Nguyen Tan Duc
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This study evaluated the water quality in the Saigon River by using biological indices based on benthic diatom communities as indicators together with physic-chemical parameters. The samples were taken in dry and wet season at seven stations along the Saigon River. Physicochemical variables and benthic diatom metrics of abundance, taxa richness (S), Shannon Wiener diversity index (H), average tolerance score per taxon (ATSPT) scores, Simpson's diversity index (D), and similarity index (J) were used in the determination of water quality of the river. The results indicated that benthic diatom metrics and the concentrations of total nitrogen, total phosphate, COD and BOD­5 characterized that the lower section of the Saigon River had lower water quality than the upper section. Shannon–Wiener diversity index indicated that water quality differed significantly between the upper course sites and the lower course sites but no significant difference was found in dry and wet season. Results demonstrated that the benthic diatom composition was more sensitive and accurate than the routine investigation of water physico-chemical parameters. Therefore, it is important to use diatoms together with water physico-chemical variables for surface water quality assessment.

Research on situation of environmental education for primary students in rural areas of Hau Giang province

Le Tran Thanh Liem, Pham Kieu Trang, Pham Ngoc Nhan
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The research: “Situation of environment education activities for primary schools in rural areas of Hau Giang province” was carried out from May 2016 to June 2017 to study the situation of education activities on environment in primary schools then to propose solutions to help improve the impact of these activities. The research focuses on education managers, teachers and students’ parents then proposes help improve the impact of these activities for primary schools. Results show that, most of teachers and students’ parents agree that environment education activities for primary students have positive impacts on raising students’ awareness on environment. Besides, these activites receive huge support from schools’ Board of Directors including providing related teaching materials, budget and delegating teachers to join these activities. However, one of the major issues is there’s not enough budget invested in two most popular activities which are adding environment education content in science subjects and organizing extra-curricular activities. The research also proposes some solutions to enhance the quality of the activities. These solutions are enhancing the engagement of education government bodies, more budget for the activities.

An evaluation of general English course from non-English major students’ learning needs analysis

Thai Cong Dan, Doan Thi Loan
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          The current research study aims to evaluate General English course (GEC) at The Southern Transport College (STC) in Can Tho City from analyzing learning needs of non-English major students to improve the quality of the course, meet students’ learning needs, and in accordance with the national criteria of curriculum design as well. The EFL students' learning needs are defined as encompassing students' reactions to GEC, language input, language skills, use of knowledge, teachers and teaching methods, testing and assessment, and learning outcome. Since the needs analysis and course evaluation were complex tasks with various possibilities of the needs, interviews of students and teachers were conducted to collect qualitative data purposing to strengthen the quantitative data from the two questionnaires. Two questionnaires of students learning needs and their evaluation of GEC were adapted from the original version of Stufflebeam’s CIPP evaluation model (1983) and Sarah Cook’s the ADDE model (2005) in Likert scales. The interview questions for students and teachers were adopted from interview questions in Mahmoud’s study (2014). The quantitative and qualitative data were analyzed to answer the two research questions: (1) What are non-English major students learning needs? (2) To what extent does general English course satisfy students’ learning needs? One hundred forty-eight students and four teachers got involved in the study as participants. The findings of the research revealed that students at STC are most interested in knowledge and language input provided from GEC. It was also determined that the students preferred extracurricular activities, watching videos or small group discussions in the language learning process. From the students’ evaluation of GEC, it was seen that their learning needs were different from the actual course they received. They fairly agree with teachers and teaching methods, testing and assessment, but the actual course does not satisfy students’ learning needs completely. Implications for teachers and school administrators are explored that they should add extracurricular activities to GEC as compulsory periods, increase the amount of periods in GEC curriculum, and open revision English courses to strengthen their English skills and test taking skills before encouraging them to register for the national examination of level A2.

Listening comprehension: First year English-major students’ perceptions and problems

Thai Cong Dan, Nguyen Ngoc Quyen
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This article reports on a study which attempts to investigate the first year English- major students’ perception of the role of listening skill development and find out the problems that they have to face while learning listening comprehension. The descriptive study was conducted with 115 of the freshmen who are studying at some universities in the Mekong Delta. The data were collected from questionnaires, interviews, and observations. The results of the study indicated that most of students held positive awareness toward the role of listening skill development and the listening comprehension problems including accent, pronunciation, speed of speech, insufficient vocabulary, different accent of speakers, lack of concentration, anxiety, and bad quality of recording were the major listening comprehension problems encountered by the first year English- major students.

Teaching practice collaborative learning in English for academic purposes writing classes at Vietnam National Economics University

Pham Thi Thanh Thuy
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The paper is a snapshot of the current practice of collaborative learning in English for Academic Purposes (EAP) writing classes at National Economics University (NEU) to show the effectiveness of collaborative learning activities in these classes. It is clear that teachers in this situation becomes facilitators who give guides when needed and do nothing but take note of how students participate into the activities as well as how students explain, give comments, ask their peers questions, and answer these questions. Besides, with collaborative learning activities, learning process takes place in a less face-threatening atmosphere with academic assistance from similar-age peers. The learning process is shifted from a passive reception to a more active process when students have chances to involve more in discussing, negotiating and arguing.

Flipped model for improving students’ English speaking performance

Tran Thi Thanh Quyen, Nguyen Van Loi
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Flipping is a creative way for teachers to maximize class time for students’ practices. Motivated by relatively productive results of flipped instructional method in teaching content subjects, the current study employed a quasi-experimental design including pre- and post- speaking tests, a questionnaire and a semi structured interview to examine the effects of a flipped classroom model on EFL students’ speaking performance. Students’ attitudes towards the model were further explored. The results showed that the students improved their speaking skills as a result of the flipped model, and they had a positive perception about the model. The study provides useful implications of integrating flipped instruction in foreign language teaching. Mo hinh lop hoc nghich dao la mot phuong phap day hoc sang tao nham giup giao vien toi da hoa thoi gian hoc va thuc hanh cho nguoi hoc. Dua tren hieu qua tich cuc cua mo hinh, nghien cuu nay thuc nghiem mo hinh de phat trien ky nang noi cho sinh vien. Cong cu nghien cuu bao gom bai kiem tra noi truoc va sau khi thuc nghiem, bang cau hoi va phong van de danh gia tac dong cua Mo hinh lop hoc nghich dao doi voi viec phat trien ky nang noi cua sinh vien va khao sat thai do cua sinh vien doi voi mo hinh. Ket qua cho thay rang, Mo hinh lop hoc nghich dao gop phan phat trien ky nang noi cho sinh vien, va cac em cung co nhung nhan thuc tich cuc ve mo hinh. Nghien cuu da mang lai nhung ung dung huu ich cua viec tich hop Mo hinh lop hoc nghich dao trong giang day ngoai ngu.

English lecturers' perceptions of improving English teaching quality through action research: What do lecturers of Can Tho University say?

Vo Phuong Quyen, Phuong Hoang Yen
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Action research (AR) in English Language Teaching (ELT) has played a significant role in improving teachers’ roles as well as their professional development. However, in the context of Can Tho University (CTU), there are few studies of action research on foreign language teaching especially English language. Therefore, this mixed method study is aimed to give deep insights into English language lecturers’ perceptions of improving teaching quality using action research. The findings revealed the positive perceptions of CTU English language lecturers about the importance of action research. However, there were certain challenges faced by these lecturers with their AR practices in terms of internal and external factors. As a result, appropriate measures to tackle such challenges in the current teaching context regarding the roles of lecturers and administrators are proposed. 

Effect of CO2 on acid-base regulation and growth performance of basa catfish (Pangasius bocourti)

Nguyen Thi Kim Ha, Nguyen Thanh Phuong, Do Thi Thanh Huong, Nguyen Thi Xuan Bieu
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This study aims to evaluate the effects of different carbon dioxide levels on blood physiological parameters and growth performance of basa catfish (Pangasius bocourti). The study included two experiments, (1) change of fish blood physiological parameters at different CO2 levels such as 1%, 2%, 3% CO2;and (2) effect of CO2 levels on fish growth performance. In the first experiment, blood samples were collected at 0, 1, 6, 24, 48, 72, 96 and 168 hrs. after equilibration to investigate pHe, pCO2, [HCO3-] and [Cl-] in plasma. The grow-out experiment was set up for 60 days and fish was weighed at the day 0, 30 and 60. The results showed that, after 1 hr. of CO2 exposure, pHe wassignificantly decreased (7.51±0.01 in control fish and 7.28±0.02 in the fish exposed to CO2 3%, this parameter was recovered after 6 hrs. pCO2 and [HCO3-] increased at all CO2 exposed groups. After 168 hrs., pCO2 and [HCO3-] in plasma of 3% CO2 exposed fish were significantly increased and reached the values of 20.7±1.35 mmHg and 22.2±1.16 mM, respectively; those pCO2 and [HCO3-] values were 2.7 and 3.2 fold as high as the values of control fish. [Cl-] concentration in plasma of fish in 2% and 3% CO2 treatments were significantly decreased after 48 hrs. of CO2 exposure in comparison with control treatment (p2 concentrations (p

Effects of nitrite exposure on haematological parameters and growth in clown knifefish (Chitala ornata, Gray 1831)

Le Thi Hong Gam, Nguyen Thanh Phuong, Nguyen Thi Thuy Vu, Do Thi Thanh Huong, Pham Ngoc Nhu
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Physiological responses and growth of clown knifefish (Chitala ornata) (initial weight of 11-12 g) exposed to nitrite were investigated with three separate experiments. The first experiment was to determine the nitrite concentration causing 50% mortality in 96 hours (96-h LC50). The second experiment examined the effects of different nitrite concentrations on haematological parameters. The third experiment investigated into the effects of different nitrite concentrations on fish growth including 4 treatments such as control, 0.2 mM nitrite, 0.4 mM nitrite, and 4 mM nitrite for measuring growth parameters at days 0, 30, 60, and 90 days (sampling 30 fish/tank). The results showed that the clown knifefish had high nitrite tolerance with 96-h LC50 of 7.82 mM. There were significant increases in methaemoglobin and leukocytes while other haematological parameters decreased during nitrite exposures at the treatment of 4 mM nitrite. Particularly, methaemoglobin and the number of leukocytes increased from 0.4 to 29.5%, and from 39.89x103 to 72.33x103 cells/mm3, respectively. Differently, there were significant declines in the number of erythrocyte (3.19x106–2.33x106 cells/mm3), haemoglobin (10.47-7.04 mM), and haematocrit (38.07-26.5%) at the highest nitrite treatment. After 90 days, daily weight gain (0.25±0.02 g/day), specific growth rate (1.18±0.07 %/day), survival rate (59%) at the treatment of 4 mM nitrite were significantly lower than those of the control, but no significant difference was observed in such parameters between the control and the treatments of 0.2 or 0.4 mM nitrite.

Stability of antioxidant phlorotannin beverage originated from Sargassum serratum on the storage time and temperature

Dang Xuan Cuong, Nguyen Van Thanh, Vu Ngoc Boi
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Stability of a product quality is usually the most interest in the technologist. The quality of beverage product is evaluated through colour value, biosubstance content and bioactivities. Therefore, total colour density, anthocyanin colour value, tannin colour value, polymer colour value, phlorotannin content and total antioxidant, reducing power and DPPH free radical scavenging activity of beverage were evaluated in 12 storage months at the room and cold temperature for the phlorotannin rich beverage with antioxidants. The beverage originated from marine algae Sargassum serratum in initial day, the phlorotannin content with activities (total antioxidant, reducing power and DPPH free radical scavenging) of 200ml of beverage orderly corresponded to 30 ± 0.01 mg phloroglucinols with activities (206.272 ± 0.233 mg ascorbic acid, 301.027 ± 0.378 mg FeSO4 and 67.45 ± 0.1 %). Total colour density, tannin colour value, polymer colour value correspond to 0.245 ± 0.002; 0.27 ± 0.001; 114.7 ± 0.01, respectively. After 12 storage months, the phlorotannin content of beverage was 66 - 79%; activities of total antioxidant, reducing power and DPPH free radical scavenging were correspond to 63.7 – 76.87%, 64.52 - 77.01% and 66.57 - 78.72% respectively, compared at initial day. Phlorotannin with antioxidant activities-rich beverage origin in marine algae Sargassum can be completely the vogue on the market.

Assessment on the technical and financial characteristics and livelihood strategy of while leg shrimp (Litopenaeus vannamei) and tiger shrimp (Penaeus monodon) farms in Cu Lao Dung district, Soc Trang province

Truong Hoang Minh
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This study was conducted from May to August, 2015 in 5 communes including An Thanh Nam, An Thanh Ba, An Thanh Nhi, An Thanh Dong and Dai An. There were 150 households were interviewed directly through questionnaires constituting of technical and financial aspects of farming system and 5 capitals of their likelihood strategy. The results showed that white leg (WLS) is the more popular cultured species compared to tiger shrimp (TS) accounting for 80% of the total number of interviewed farmers (120 households). In particularly, the total water surface area spent for white leg shrimp culture was 0.63±0.56 ha/household and for tiger shrimp was 0.62±0.41 ha/household with the average pond areas were 0.33±0.17 and 0.35±0.14 ha respectively. The average of shrimp stocking density for WLS was 83 individual/m2 and 31 individual/m2for TS (P

A study of fixed points and Hopf bifurcation of Fitzhugh-Nagumo model

Phan Van Long Em
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In this article, a class of FitzHugh-Nagumo model is studied. First we are finding all necessary conditions for the parameters of system such that we have just one stable fixed point which presents the resting state for this famous model. After that, by using the Hopf’s theorem, we proof analytically the existence of a Hopf bifurcation that is a critical point where a system’s stability switches and a periodic solution arises. More precisely, it is a local bifurcation in which a fixed point of a dynamical system loses stability, as a pair of complex conjugate eigenvalues cross the complex plane imaginary axis. With  reasonably generic assumptions for the dynamical system, a small-amplitude limit cycle branches from the fixed point.

English lecturers’ perceptions and practices of research engagement: The case of Can Tho University

Luu Bich Ngoc, Phuong Hoang Yen, Ly Thi Bich Phuong, Vo Phuong Quyen
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Engaging in research has been claimed to bring lecturers various benefits regarding their teaching and professional development. In Vietnam, lecturers have been mobilized to engage in research via various regulations and degrees by the government. However, not many English lecturers engage in research. The current study was conducted with fifty-six English lecturers from Can Tho University (CTU) to explore their perceptions and practices of research engagement. The results of the study revealed their positive but technical perceptions and moderate levels of research engagement. From the survey results, suggestions for promoting research engagement among English lecturers would be discussed.