Individual factors that keep online English learners from greater success: the case of HCMC Open University

A variety of challenges in online training are found in numerous learning environments such as cultural background, accessibility, technology, learning content and so on. In the developed or western societies, the online training has been developing in a stable way for decades, while numerous typical obstacles seem to be visible in developing countries including student support, flexibility, teaching and learning activities, access, academic confidence, localization and attitudes (Andersson, 2008). These difficulties are not excluded in the context of online English training system (OETS) at Ho Chi Minh City Open University (HCMCOU). Although this institution ever makes effort to limit these possible challenges for ages, plenty of impactful issues leading to serious difficulties of OETS also obviously exist. Hence, to fully explore the key factors that cause greater barriers in this training system, a qualitative on traditions of bioghaphy and grounded theory method was applied. The qualitative data is to be collected from the responses on openended questionaire sent for 30 online English majors and indirect interviews with 5 salient learners were also conducted. The findings show that some minor limitations of learners such as negative learning habits, willpower shortage and neglected learning perception lead to greater barriers of online English training

NOISE TRADER RISK: EVIDENCE FROM VIETNAM STOCK MARKET

Abstract: This paper investigates the existence of noise trader risk in Vietnam’s stock market and its effect on the daily returns of stock prices. The methodologies contain the estimation of GARCH (1,1) model to filter the residuals using the moving average method to calculate the impact of information traders. Noise trader risk or the risk that is caused by noise traders is derived by subtracting the residuals by the rational traders’ impact. We find that the noise trader risk does exist in Vietnam’s stock market and its impact on daily returns of stocks is unpredictable. Meanwhile, we find a positive impact of information traders on the stock returns. It increases the daily stock returns, and in turn, helps the market to correct itself because the stock prices move back to its fundamental value.Keywords: noise trader risk, GARCH (1,1), Vietnam’s stock marke

Numerical modeling of thermal dust polarization from aligned grains in the envelope of evolved stars with updated POLARIS

Magnetic fields are thought to influence the formation and evolution of evolved star envelopes. Thermal dust polarization from magnetically aligned grains is potentially a powerful tool for probing magnetic fields and dust properties in these circumstellar environments. In this paper, we present numerical modeling of thermal dust polarization from the envelope of IK Tau using the magnetically enhanced radiative torque (MRAT) alignment theory implemented in our updated POLARIS code. Due to the strong stellar radiation field, the minimum size required for RAT alignment of silicate grains is $\sim 0.005 - 0.05\,\rm\mu m$. Additionally, ordinary paramagnetic grains can achieve perfect alignment by MRAT in the inner regions of $r < 500\,\rm au$ due to stronger magnetic fields of $B\sim 10$ mG - 1G, producing thermal dust polarization degree of $\sim 10\,\%$. The polarization degree can be enhanced to $\sim 20-40\%$ for grains with embedded iron inclusions. We also find that the magnetic field geometry affects the alignment size and the resulting polarization degree due to the projection effect in the plane-of-sky. We also study the spectrum of polarized thermal dust emission and find the increased polarization degree toward $\lambda > 50\,\rm\mu m$ due to the alignment of small grains by MRAT. Furthermore, we investigate the impact of rotational disruption by RATs (RAT-D) and find the RAT-D effect cause a decrease in the dust polarization fraction. Finally, we compare our numerical results with available polarization data observed by SOFIA/HAWC+ for constraining dust properties, suggesting grains are unlikely to have embedded iron clusters and might have slightly elongated shapes. Our modeling results suggest further observational studies at far-infrared/sub-millimeter wavelengths to understand the properties of magnetic fields and dust in AGB envelopes.Comment: 27 pages, 23 figures, 1 table, to be submitte

Premnaodoroside A and 10-o-trans-p-methoxycinnamoylcatalpol, two iridoid glycoside derivatives from the leaves of Premna integrifolia L

From the leaves of Premna integrifolia L. two iridoid glycoside derivatives premnaodoroside A (1) and 10-O-trans-p-methoxycinnamoylcatalpol (2) were isolated. Their chemical structures were elucidated by means of ESI-mass MS, 1H-NMR, 13C-NMR (CPD and DEPT), HSQC, and HMBC spectra in comparison with the literature. This is the first report of 1 and 2 from P. integrifolia species

Clinical and Virological Features of Dengue in Vietnamese Infants

Dengue is a major public health problem in tropical and subtropical countries, including Vietnam. Dengue cases occur in children and young adults; however, severe dengue also occurs in infants less than 1 year of age. Prompt recognition of dengue is important for appropriate case management, particularly in infants in whom febrile illness from other causes is common. We describe the clinical picture, virological and immunological characteristics of infants with dengue admitted to three hospitals in southern Vietnam, compared with infants admitted with fever not due to dengue. We show that infants with dengue are difficult to distinguish from those with other febrile illnesses based on signs and symptoms at presentation, and so laboratory tests to confirm dengue virus infection may be useful for diagnosis and management. Conventional diagnostic methods for dengue have low sensitivity early in infection, and we show that an alternative antigen-detection assay that has demonstrated good sensitivity and specificity in older age groups also performs well in infants. This study will help to inform the diagnosis and management of dengue in infants

Dexamethasone and long-term outcome of tuberculous meningitis in Vietnamese adults and adolescents.

BACKGROUND: Dexamethasone has been shown to reduce mortality in patients with tuberculous meningitis but the long-term outcome of the disease is unknown. METHODS: Vietnamese adults and adolescents with tuberculous meningitis recruited to a randomised, double-blind, placebo-controlled trial of adjunctive dexamethasone were followed-up at five years, to determine the effect of dexamethasone on long-term survival and neurological disability. RESULTS: 545 patients were randomised to receive either dexamethasone (274 patients) or placebo (271 patients). 50 patients (9.2%) were lost to follow-up at five years. In all patients two-year survival, probabilities tended to be higher in the dexamethasone arm (0.63 versus 0.55; p = 0.07) but five-year survival rates were similar (0.54 versus 0.51, p = 0.51) in both groups. In patients with grade 1 TBM, but not with grade 2 or grade 3 TBM, the benefit of dexamethasone treatment tended to persist over time (five-year survival probabilities 0.69 versus 0.55, p = 0.07) but there was no conclusive evidence of treatment effect heterogeneity by TBM grade (p = 0.36). The dexamethasone group had a similar proportion of severely disabled patients among survivors at five years as the placebo group (17/128, 13.2% vs. 17/116, 14.7%) and there was no significant association between dexamethasone treatment and disability status at five years (p = 0.32). CONCLUSIONS: Adjunctive dexamethasone appears to improve the probability of survival in patients with TBM, until at least two years of follow-up. We could not demonstrate a five-year survival benefit of dexamethasone treatment which may be confined to patients with grade 1 TBM. TRIAL REGISTRATION: ClinicalTrials.gov NCT01317654

Sample size requirements for separating out the effects of combination treatments: Randomised controlled trials of combination therapy vs. standard treatment compared to factorial designs for patients with tuberculous meningitis

<p>Abstract</p> <p>Background</p> <p>In certain diseases clinical experts may judge that the intervention with the best prospects is the addition of two treatments to the standard of care. This can either be tested with a simple randomized trial of combination versus standard treatment or with a 2 × 2 factorial design.</p> <p>Methods</p> <p>We compared the two approaches using the design of a new trial in tuberculous meningitis as an example. In that trial the combination of 2 drugs added to standard treatment is assumed to reduce the hazard of death by 30% and the sample size of the combination trial to achieve 80% power is 750 patients. We calculated the power of corresponding factorial designs with one- to sixteen-fold the sample size of the combination trial depending on the contribution of each individual drug to the combination treatment effect and the strength of an interaction between the two.</p> <p>Results</p> <p>In the absence of an interaction, an eight-fold increase in sample size for the factorial design as compared to the combination trial is required to get 80% power to jointly detect effects of both drugs if the contribution of the less potent treatment to the total effect is at least 35%. An eight-fold sample size increase also provides a power of 76% to detect a qualitative interaction at the one-sided 10% significance level if the individual effects of both drugs are equal. Factorial designs with a lower sample size have a high chance to be underpowered, to show significance of only one drug even if both are equally effective, and to miss important interactions.</p> <p>Conclusions</p> <p>Pragmatic combination trials of multiple interventions versus standard therapy are valuable in diseases with a limited patient pool if all interventions test the same treatment concept, it is considered likely that either both or none of the individual interventions are effective, and only moderate drug interactions are suspected. An adequately powered 2 × 2 factorial design to detect effects of individual drugs would require at least 8-fold the sample size of the combination trial.</p> <p>Trial registration</p> <p>Current Controlled Trials <a href="http://www.controlled-trials.com/ISRCTN61649292">ISRCTN61649292</a></p

Studying Magnetic Fields and Dust in M17 Using Polarized Thermal Dust Emission Observed by SOFIA/HAWC

We report on the highest spatial resolution measurement to date of magnetic fields (B-fields) in M17 using thermal dust polarization measurements taken by SOFIA/HAWC+ centered at a wavelength of 154 μm. Using the Davis–Chandrasekhar–Fermi method, in which the polarization angle dispersion calculated using the structure function technique is the quantity directly observed by SOFIA/HAWC+, we found the presence of strong B-fields of 980 ± 230 and 1665 ± 885 μG in the lower-density M17-N and higher-density M17-S regions, respectively. The B-field morphology in M17-N possibly mimics the fields in gravitationally collapsing molecular cores, while in M17-S the fields run perpendicular to the density structure. M17-S also displays a pillar feature and an asymmetric large-scale hourglass-shaped field. We use the mean B-field strengths to determine Alfvénic Mach numbers for both regions, finding that B-fields dominate over turbulence. We calculate the mass-to-flux ratio, λ, finding λ = 0.07 for M17-N and 0.28 for M17-S. These subcritical λ values are consistent with the lack of massive stars formed in M17. To study dust physics, we analyze the relationship between dust polarization fraction, p, emission intensity, I, gas column density, N(H2), polarization angle dispersion function, S, and dust temperature, T d. p decreases with intensity as I −α with α = 0.51. p tends to first increase with T d, but then decreases at higher T d. The latter feature, seen in M17-N at high T d when N(H2) and S decrease, is evidence of the radiative torque disruption effect

Chemical constituents from fruits of Hydnocarpus hainanensis Merr. (Flacourtiaceae) in Vietnam

Five compounds were isolated from the fruits of Hydnocarpus hainanensis Merr. Sleum. (Flacourtiaceae). Their structures were determined by spectroscopic analysis including MS and NMR. The isolates were identified as taraktophyllin (1), hydnocarpic acid (2), 3,4-dihydroxybenzyl alcohol (3), 3,4-dihydroxybenzoic acid (4) and 3-hydroxy-4-methoxybenzoic acid (5)

Secondary metabolites from Micromonospora ectrinospora G017

Eight  compounds, cyclo-(Pro-Tryp) (1), N-[2-(1H-indol-3-yl)-2-oxo-ethyl] acetamide (2), cyclo-(Pro-Tyr) (3), cyclo-(Pro-Phe) (4), cyclo-trans-4-OH-(Pro-Phe) (5), cyclo-(Pro-Leu) (6), cyclo-(Pro-Val) (7), and  uracil (8) were isolated from the culture broth of the marine Micromonospora ectrinospora G017 strain. The structures of the isolated compounds were established on the basis of their spectral data, including mass spectrometry and NMR