On the existence of orthonormal geodesic bases for Lie algebras

We show that every unimodular Lie algebra, of dimension at most 4, equipped with an inner product, possesses an orthonormal basis comprised of geodesic elements. On the other hand, we give an example of a solvable unimodular Lie algebra of dimension 5 that has no orthonormal geodesic basis, for any inner product

COMPUTER INTERACTIVE TEACHING TECHNOLOGY FOR ELECTRONICS ENGINEERING UNIVERSITY.

Virtual reality technology currently tends to develop and apply strongly in all areas of social life. Therefore, the application of virtual reality technology in education and training is becoming more and more urgent. If we know how to effectively exploit and apply virtual reality technology to the design of the education and training process, the teaching of teachers and the acquisition of learners' knowledge will become easy, born dynamic. However, in order to achieve high efficiency, it is necessary to have a creative, flexible and appropriate application based on the actual conditions of each field, each school, the learning ability of learners, the ability to use using modern teaching facilities of teachers, specific subject

Survey on Mutation-based Test Data Generation

The critical activity of testing is the systematic selection of suitable test cases, which be able to reveal highly the faults. Therefore, mutation coverage is an effective criterion for generating test data. Since the test data generation process is very labor intensive, time-consuming and error-prone when done manually, the automation of this process is highly aspired. The researches about automatic test data generation contributed a set of tools, approaches, development and empirical results. In this paper, we will analyse and conduct a comprehensive survey on generating test data based on mutation. The paper also analyses the trends in this field

Reported weather shocks and rural household welfare : Evidence from panel data in Northeast Thailand and Central Vietnam

Extreme weather events are reported to have severe effects on rural households in the developing world. This study uses a unique and comparable panel dataset of about 4000 rural households collected in three years (2010, 2013, and 2016) from Northeast Thailand and Central Vietnam to examine and compare the welfare effects of floods, droughts, and storms reported to be experienced by rural households. Our results show that these weather shocks have significant effects on household income, consumption, and poverty in both countries, though the levels of severity are different. Drought is the common extreme weather event in these two countries with significant and negative effects on household income, consumption and poverty. In Thailand, floods have higher impacts on rural households in terms of income and poverty than storms do. Compared to Thailand, Vietnam is more exposed and significantly affected by storms. In addition to weather shocks, the welfare of rural households is significantly affected by other factors representing their livelihood platforms. Promoting farm mechanization and rural education should be given high priority in both countries. In Thailand, the accumulation of farmland should also be encouraged. In Vietnam, accelerating internet access and supporting livestock production would contribute to increasing household income and consumption and consequently decreasing poverty

Using Fine-Grained Sediment and Wave Attenuation as a New Measure for Evaluating the Efficacy of Offshore Breakwaters in Stabilizing an Eroded Muddy Coast: Insights from Ca Mau, the Mekong Delta of Vietnam

Offshore breakwaters can be effective in reducing the energy of incident waves through dissipation, refraction or reflection. Breakwaters are increasingly constructed to stabilize eroded muddy coasts, particularly in developing countries. Accumulation of fine-grained sediment and wave attenuation are two attributes of a stable muddy coast. Effective interventions in stabilizing eroded muddy coasts include two important elements: accumulation of fine-grained sediment and wave reduction. The efficacy of offshore breakwaters in stabilizing eroded muddy coasts is, however, not yet adequately understood. A crucial question needing attention is whether accumulation of fine-grained sediment and wave attenuation should be used in evaluating the efficacy of these offshore breakwaters in stabilizing eroded muddy coasts. To address this issue, a pile-rock offshore breakwater in Huong Mai, Tieu Dua of Ca Mau, Vietnam was selected as an appropriate example in this regard. Accumulation of fine-grained sediment and wave attenuation were tested as means to investigate the efficacy of the Huong Mai structure in stabilizing the eroded muddy coast. The study was undertaken using field-based measurements and semi-structured interviews in three stages between October 2016 and December 2020. We found that this structure has had limited efficacy in stabilizing the eroded muddy coast. The structure was effective in dissipating the energy of incident waves, but we found no evidence of fine-grained sediment accumulation due to an inappropriate structural design. There was also no monitoring system in place, leading to difficulties in evaluating its efficacy in terms of wave attenuation and accumulation of fine-grained sediment. The gaps between the shoreline and the structure have not been adequately explained, resulting in substantial challenges in replicating the structure elsewhere. The Huong Mai structure should be strengthened using supplementary measures and granulometric tests in order to improve the efficacy in stabilizing eroded muddy coasts. The methods in this study provide new insights in this regard

Antioxidant activity of isolated compounds from ethyl acetate extract of Bruguiera parviflora

Bruguiera parviflora belongs to Bruguiera genus, which possesses several biological activities such as antidiabetic, anti-inflammatory, and antioxidant. Phytochemical investigation of the ethyl acetate extract from Bruguiera parviflora leaves was carried out bioassay-guided isolation and obtained three known compounds, namely kochioside A (1), oleanolic acid (2) and quercitrin (3). The chemical structures of isolated compounds were identified by spectroscopic method and comparison with previously published data. All isolated compounds were evaluated for antioxidant activity with the free radical scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH). Among them, quercitrin (3) was the most potent compound against DPPH radical with the IC50 value of 16.4 ± 0.2 µg/mL, compared to vitamin C, which was used as a positive control

The impacts of rhetorical schema on English majors’ listening comprehension in academic situations at Ho Chi Minh City University of Technology And Education

Listening is a basic language skill which involves the interaction of diverse factors affecting learners’ listening comprehension. Learners often encounter various difficulties in listening to an oral text with a little knowledge of the reasons why it occurs. Moreover, teachers mainly pay more attention to it as a product rather than as a process. Also, the factors about listening strategies have been under-researched although they play a significant role in guiding learners through what to listen to and how to listen to it effectively. This study sought to investigate the effects of rhetorical schema including note-taking and four listening strategies, and the extent to which students change as regards strategy use and listening achievement in academic settings. Forty second-year EFL students from the two listening classes, one treated as the experimental group (EG) and the other as the control group (CG), at the Faculty of Foreign Languages of the Ho Chi Minh City University of Technology and Education (HCM UTE) were invited to participate in the study. Data were collected in the form of a questionnaire administered to EG and listening tests of IELTS part 4 taken by both groups. The findings indicate that EG students are more open to use the strategies introduced, so rhetorical schema positively enhance their listening comprehension. Notably, the scores of the rank high - distinction - appeared for the first time albeit its small percentage in EG. Students also express significant changes in their attitudes towards rhetorical strategies in terms of their awareness of its importance, frequent use, and confidence in listening to lectures in the future

Dinophysis spp. recorded in the coastal waters of northern Vietnam during 2002-2003

A monitoring on toxins responsible for Diarrhetic Shellfish Poisoning (DSP) was carried out at several culture areas of hard clam (Meretrix meretrix) in the northern coast of Vietnam during May 2002 and December 2003. Quantitative observation of Dinophysis spp. was made one to four times every month and DSP toxins in the hard clam grown in the area was analyzed monthly using the HPLC method. Six species of Dinophysis were recorded, including D. caudata, D. fortii, D. miles, D. rotundata, D. mitra and D. hastata. Among them, D. caudata was the most common species. Others were not common and their densities were ignorable. D. caudata appeared almost all around the year at all sampling sites with density ranged from 0 to more than 3000 cells/l. However, it was more abundant during the warm period, i.e. from late February to late November. For the rest of a year, cells were rarely found. D. caudata was recorded in a wide range of temperature (15-34.3℃), but its significant density (over 100 cells/l) was only observed when water temperature exceeded 20℃. D. caudata appeared and could reach high density at all salinity in the range of 8-34 PSU. The highest recorded density was 3128 cells/l at 22℃ and 8.2 PSU in Thanh Hoa area in February 2003. ""Blooms"" of D. caudata, together with other dominant dinoflagellates, usually coincided with the vanishing period of diatoms. Okadaic acid (OA) was detected in edible part of clams but at low concentration in all samples. Maximal level was 80ng OA/100g, encountered in Thanh Hoa transect during August 2002 and April 2003. DTX 1-4 were not detected in all samples. No significant correlation between OA concentration in clam and the density of D. caudata in the water sample was observed, although toxins sometimes peaked the same time with D. caudata density. Low concentration of toxins implicates low risk of DSP and explains the absence of poisoning cases in the area so far. However, other shellfishes in the area should also be subjected to toxin monitoring