STUDY OF NEGATIVE REFRACTIVE INDEX IN Rb FOUR-LEVEL N-TYPE ATOMIC GAS MEDIUM

In this work, we study the generation of a negative refractive index based on electromagnetically induced transparency (EIT) in a Rb four-level N-type atomic gas medium. We derive analytic expressions for the relative permittivity and relative permeability of the medium according to the parameters of the probe, pump, and signal laser fields. We then investigate the variation of the real parts of the relative permittivity and relative permeability with respect to the intensity and frequency of the pump and signal laser fields. In the presence of the pump laser beam, the medium becomes transparent to the probe laser beam even in the resonant region. At the same time, the real parts of the relative permittivity and relative permeability are simultaneously negative (i.e., the medium exhibits a negative refractive index) in the EIT spectral domain. In the presence of the signal laser beam, the EIT effect occurs over two different frequency domains of the probe beam, so a negative refractive index is also generated in these two frequency domains. The investigation of the real parts of the relative permittivity and relative permeability with intensity and frequency of the pump and signal laser fields allowed us to find the laser parameters for the appearance of the negative refractive index, which can be useful for experimental observations

Description of Geocenamus vietnamensis sp. n. (Nematoda : Merliniidae) from Vietnam

A new species of the genus Geocenamus was isolated from soil and root samples from the rhizosphere of Casuarina equisetifolia (Casuarinaceae) in Quang Nam province, Vietnam. This species is characterized by a round-to-hexagonal labial disc, the presence of a labial region, which is continuous or slightly offset from the body with six sectors, lateral sectors of first labial annulus being smaller than the submedian sectors, the presence of six to seven labial annules; the absence of deirids; stylet length 24 to 28 mu m long, body length 776 to 979 mu m long; lateral field with six to eight lateral lines, without areolation at mid-body and with areolation in outer bands at the tail region and a pointed tail terminus. Geocenamus vietnamensis n. sp. most closely resembles G. boghiae in having a non-sclerotized head framework and lacking a bursa in the males. It can be clearly distinguished from all other species of the genus Geocenamus by these characteristics. The combination of morphology, morphometric features, and phylogenetic trees, based on D2-D3 of 28S and ITS rDNA sequences, showed that this new species can be clearly separated from all other sequenced species. This record is the first for Geocenamus in Vietnam

Morphological and molecular characteristics of Pratylenchus haiduongensis sp. n., a new species of root-lesion nematodes associated with carrot in Vietnam

Pratylenchus haiduongensis sp. n. is described as associated with carrot (Daucus carota subsp. sativus (Hoffm.) Schubl. & G. Martens) in Hai Duong Province, Vietnam. P. haiduongensis sp. n. is characterized by the lip region with three annuli and slightly separated from the body. Stylet knobs are rounded (never indented anteriorly). The lateral field includes four incisures, bearing areolation at the pharynx region and tail region and occasionally appears in the vulval region. Sometimes the appearances of oblique broken striaes divide the lateral field into five or six incisures. The ovary is distinct with one row of oocytes. Spermatheca is oval in shape with round central cavity, without sperm or reduced in some specimens. The postvuval uterine sac is long surpassing the vulva body diameter by 2 to 2.5 times (PUS = 31 to 65 mm). High vulva position with V = 66 to 75%. The tail shape can be subhemispherical with a smooth, slightly indented, broadly smooth, or cleft terminus observed in some specimens. The matrix code of P. haiduongensis sp. n. is: A2, B1, C4, D(1,3), E1, F(5,6), G(1,2), H(1,4); I(1,2,3,4), J1, K(1,2) according to Castillo and Vovlas (2007). The LSU-D2D3 segment and the ITS-rDNA region of this species were amplified and sequenced. The morphological characters and molecular phylogenetic analyses confirmed that this is a new species of the genus Pratylenchus in Vietnam

Practice environmental cost management accounting: The case of Vietnamese brick production companies

During the past few years, there has been a growing interest in applications of environmental cost management accounting (ECMA) in different manufacturing industries. ECMA is a useful tool for environmental performance improvement and achieving better financial benefits. Nevertheless, ECMA implementation is in early stages in many countries such as Vietnam. Brick industry is one of the most polluted sectors, which has significant impact on the environment. The purpose of this paper is to provide a clear image of ECMA application in Vietnamese brick manufacturing enterprises. Both qualitative and quantitative research methodologies are used to analyze the participants' attitudes, perceptions and concerns about the potential for applying ECMA. The results indicate that the brick industry adopted low level of ECMA and provide some necessary suggestions to promote the enterprises applying ECMA

Auditing financial statements in insurance enterprises: The case of Vietnam

This study is conducted to study the implementation of the audit techniques and procedures executed by auditors using risk-based approach. The study also determines factors affecting audit quality of financial statements in Vietnamese insurance enterprises. Quantitative method is used in the study where questionnaires are sent to 250 independent auditors and 186 valid questionnaires are encrypted, declared and entered into SPSS software version 22.0. The results show that in audit techniques, except for document testing and verification technique, there were significant differences in application level of material testing, observation, interview, calculation and analysis techniques between big 4 firms and non-big 4 firms. The analysis also confirms that the most significant difference was between the two audit groups. In audit procedures, while control testing is not performed singly, detailed testing can be performed alone at all three assurance levels and the analysis is performed alone in the assurance level of 1. It is possible to combine them in these proce-dures with the assurance level of 2 and 3. On the other hand, the combination of these three proce-dures is only guaranteed at level 3. The results of the factor analysis and regression model test demonstrate that there were six factors influencing the audit quality of financial statements in insur-ance enterprises; namely audit method, auditors’ quality, awareness of auditors and director board, characteristics of insurance enterprises, legal environment and position of the audit firm. In particular, audit method and auditors’ quality are the strongest factors

Ecological Engineering and Restoration of Eroded Muddy Coasts in South East Asia: Knowledge Gaps and Recommendations

Ecological engineering (EE) was employed for developing strategies for stabilizing eroded muddy coasts (EMCs). However, there was a limited analysis of these EE strategies with respect to design, performance, and lessons learned. This study employed a critical review for addressing the limitations. There were four EE models designed with different restoration interventions for stabilizing EMCs. The models using active interventions have not been cost-effective in controlling erosion because the interventions failed to achieve their goals or were costly and unnecessary. Of the two passive intervention models, the one with structures constructed from onshore proved to be more cost-effective in terms of construction costs, the survival rate of transplanted seedlings, and levels of sea mud accumulation. Interventions with adequate consideration of the muddy coastal ecological processes and the ecological reasoning for the positioning of these interventions play a crucial role in stabilizing EMCs. A passive restoration model using gradually expanded interventions should be promoted in order to ensure sustainable management of EMCs in the future

Carrot hairy roots (Daucus carota L.) characterisation and optimisation for high β‐carotene extraction

Hairy roots are widely known as a biological system for the production of highly diverse biomolecules. β‐carotene – a precursor for vitamin A – is known to be an anti‐oxidant and anti‐gastric cancer and protection agent against cardiovascular disease, heart disease and stroke. β‐carotene has been chemically synthesised and consumed by humans. However, the chemical process often produces a by‐product that may be harmful to human health. Therefore, this study established a protocol to induce hairy roots (HRs) from a Vietnamese carrot variety and produce natural β‐carotene. The Rhizobium rhizogenes ATCC15834 harbouring Ri plasmid and a Vietnamese carrot variety were used as materials for genetic transformation and HR induction studies. The result showed that approximately 50 HR lines were obtained. Culture medium supplemented with 30 mg/L of sucrose that gave the highest biomass of HR was shown in carrot HR line 30, which had a doubling time of 6.5 days. The highest content of β‐carotene extraction, at 128 mg/100g hairy roots, was achieved with a ratio volume (v/v) of 2‐propanol and plant samples of 20:1, followed by two hours’ incubation with 2‐propanol at 60 °C. Our study reveals a highly efficient protocol for Vietnamese carrot hairy root establishment and multiplication. A very efficient protocol for β‐carotene extraction from the hairy root was established to produce natural β‐carotene that achieves the same β‐carotene quantity as that produced by normal roots. This study provides new insight into the production of high‐content and natural β‐carotene for therapeutic application

EXTRACURRICULAR SPORTS: POPULAR CONTENTS AND FORMS AMONG STUDENTS IN THE DORMITORY OF VIETNAM NATIONAL UNIVERSITY HO CHI MINH CITY

This article is written to provide thorough information about popular contents and forms of extracurricular sports performed by university students at a dormitory of Vietnam National University Ho Chi Minh City (VNUHCMC). The study uses document references, surveys, and statistical mathematics to investigate what extracurricular sports are favored by the students and how they organize their practices. The results indicate that the majority of students choose to practice football, volleyball, badminton, athletics, and martial arts. They play with themselves and/or in teams, without instructors, from 30 minutes to 02 hours in the afternoon after school time and/or in the morning, at the dormitory and/or sports centers.  Article visualizations

PHYSICAL CONDITION OF MALE STUDENTS AT VIETNAM NATIONAL UNIVERSITY OF HO CHI MINH CITY DORMITORY

The purpose of the study is to provide information about the current physical condition of 19-year-old male students of the Vietnam National University of Ho Chi Minh City (VNUHCMC) dormitory. The research used the methods of synthesizing sport-related documents, interviewing experts, applying pedagogical tests, and statistical analysis to determine appropriate physical fitness assessment tests. Afterward, the figures for the physical condition of male students at the VNUHCMC dormitory were compared with that of the average Vietnamese people, of Hanoi National University (HNU), University of Danang (UD), Can Tho University (CTU), and Ho Chi Minh City (HCMC) students at the same age and gender, and with the standard shown in Decision 53/2008/BGDDT of the Ministry of Education and Training. The results show that the “good” group accounts for 28.75%, the “acceptable” group for 23.19% and the “failed” group for 48.06%. It is notable that the agility, leg muscular strength, endurance, and motor skills of 19-year-old male students at the VNUHCMC dormitory are greater than the average physical fitness of Vietnamese people, as well as students of the same age and gender at HNU, UD, and CTU. Their endurance is also higher than that of male HCMC pupils of the same age, but their leg muscular strength and motor abilities are almost comparable.  Article visualizations

Study on structure of the Earth’s crust in Thua Thien-Hue province and adjacent areas by using gravity and magnetic data in combination

This paper presents the structural characteristics of the Earth’s crust in Thua Thien-Hue province and adjacent area based on interpretation of gravity and magnetic data in combination. Research results have shown that: The depth of crystalline basement varies complicatedly, in the range of 0–11 km. The depth of Conrad surface increases from Northeast (12 km) to Southwest (18 km) and the depth of Moho surface is 23–34 km; The density of sedimentary layer changes from 2.61 g/cm3 to 2.65 g/cm3. Meanwhile, the density of granitic layer is in the range of 2.68–2.73 g/cm3. The basaltic layer has the density value of 2.88–2.93 g/cm3 and the average density of lower layer of the Earth’s crust is about 3.30 g/cm3; The depth of second-order faults, Red River and A Luoi - Rao Quan, is through the Earth’s crust. Meanwhile, the depth of influence of third-order faults, Chay river, Dong Ha - Phu Vang, Vinh Linh, Hue - Son Tra and Tam Ky - Phuoc Son, is within the thickness of the Earth’s crust