EFFECTIVENESS OF POWERPOINT PRESENTATION ON VOCABULARY RETENTION OF EFL FIRST-YEAR STUDENTS’ READING COMPREHENSION

Vocabulary learning plays an important role in language learning. To many language learners, lack of vocabulary is one of the biggest obstacles that prevent them from mastering the language. Moreover, there have been a lot of studies conducted to find out the way to help language learners acquire and retain learned vocabulary. Among them, PowerPoint is suggested by many researchers as one good way to help learners learn vocabulary retention through reading comprehension. The purpose of this study was to investigate the effect of PowerPoint on vocabulary retention in reading comprehension of EFL (English as a Foreign Language) first-year students at Long An University of Economics and Industry (DLA), Long An Province, Vietnam. Besides, this study investigates learners’ attitudes towards the use of PowerPoint in learning vocabulary. The participants were 60 non-English major students at DLA. Two instruments were (1) the tests on English vocabulary, (2) the questionnaire on the participants’ attitudes towards the use of PowerPoint in teaching and learning vocabulary, were investigated. The results demonstrated a significant difference in learners’ vocabulary retention: the participants in the experimental group remembered vocabulary longer than those in the control group. The study showed that the learners had positive attitudes towards the use of PPT (PowerPoint Presentation) in learning vocabulary retention.  Article visualizations

LP 714-37: A wide pair of ultracool dwarfs actually is a triple

LP 714-37 was identified by Phan-Bao et al. (2005) as one of the very few wide pairs of very low mass (VLM) stars known to date, with a separation of 33 AU. Here we present adaptive optics imaging which resolves the secondary of the wide pair into a tighter binary, with a projected angular separation of 0.36 arcsec, or 7 AU. The estimated spectral types of LP 714-37B and LP 714-37C are M8.0 and M8.5. We discuss the implications of this finding for brown dwarf formation scenarios.Comment: Accepted by ApJ Letter

Magnetic Field Topology in Low-Mass Stars: Spectropolarimetric Observations of M Dwarfs

(ABRIDGED) We report here our mapping of the magnetic field topology of the M4 dwarf G 164-31 (or Gl 490B), which is expected to be fully convective, based on time series data collected from 20 hours of observations spread over 3 successive nights with the ESPaDOnS spectropolarimeter. Our tomographic imaging technique applied to time series of rotationally modulated circularly polarized profiles reveals an axisymmetric large-scale poloidal magnetic field on the M4 dwarf. We then apply a synthetic spectrum fitting technique for measuring the average magnetic flux on the star. The flux measured in G 164-31 is Bf = 3.2+-0.4 kG, which is significantly greater than the average value of 0.68 kG determined from the imaging technique. The difference indicates that a significant fraction of the stellar magnetic energy is stored in small-scale structures at the surface of G 164-31. Our H_alpha emission light curve shows evidence for rotational modulation suggesting the presence of localized structure in the chromosphere of this M dwarf. The radius of the M4 dwarf derived from the rotational period and the projected equatorial velocity is at least 30% larger than that predicted from theoretical models. We argue that this discrepancy is likely primarily due to the young nature of G 164-31 rather than primarily due to magnetic field effects, indicating that age is an important factor which should be considered in the interpretation of this observational result. We also report here our polarimetric observations of five other M dwarfs with spectral types from M0 to M4.5, three of them showing strong Zeeman signatures.Comment: 16 pages, 6 figures, accepted by Ap

Lower and upper bound intercept probability analysis in amplifier-and-forward time switching relaying half-duplex with impact the eavesdropper

In this paper, we proposed and investigated the amplifier-and-forward (AF) time switching relaying half-duplex with impact the eavesdropper. In this system model, the source (S) and the destination (D) communicate with each other via a helping of the relay (R) in the presence of the eavesdropper (E). The R harvests energy from the S and uses this energy for information transferring to the D. For deriving the system performance, the lower and upper bound system intercept probability (IP) is proposed and demonstrated. Furthermore, the Monte Carlo simulation is provided to justify the correctness of the mathematical, analytical expression of the lower and upper bound IP. The results show that the analytical and the simulation curves are the same in connection with the primary system parameters

Self-injurious Behavior of Children with Autism in Vietnam: Across Sectional Study

This study explored self-injurious behaviour (SIB) of autistic children in Vietnam through a crosssectional design. 60 informants, including 57 parents and 3 caregivers completed the questionnaire on problem behaviour consisting of aggression, self-injury, stereotyping, property destruction, other problem behaviours and their functions. Results revealed that children experienced all mentioned problem behaviours, especially self-injurious behaviour. The topographies of self-injurious behaviour of the children included head-hitting, head-scratching, head-banging, hair-pulling, face-hitting, facepuncturing with a pen, ear-scratching, lip-picking, hand-biting, hand-scratching, hand-pinching, and belly-scratching. The most common area of self-injurious behaviour is the head. The functions of these problem behaviours were expressed in four types (social positive reinforcement, social negative reinforcement, automatic positive reinforcement and automatic negative reinforcement). Social positive reinforcement appeared as a prominent function. Out of these 57 children, 21 of them who were autistic with self-injurious behaviour went through a functional behaviour assessment (FBA) in which the four conditions known as attention, tangible items, escape from task/activities, automatic stimulation were tested. The results of functional behaviour assessment (FBA) further indicated the correspondence between the FAST-R and FBA outcome on function of problem behaviour, especially self-injurious behaviour. The research concluded that the prominent function of these self-injurious behaviours was social function. It means self-injurious behaviours usually occur within a condition of social interaction, especially, in this present study, in the tangible condition. The antecedent of selfinjurious behaviour is the removal of tangibles (e.g. food, preferred items). This paper contributes to our knowledge of self-injurious behaviour of children with autism in Vietnam where empirical research of this field was still very rare

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

First Confirmed Detection of a Bipolar Molecular Outflow from a Young Brown Dwarf

Studying the earliest stages in the birth of stars is crucial for understanding how they form. Brown dwarfs with masses between that of stars and planets are not massive enough to maintain stable hydrogen-burning fusion reactions during most of their lifetime. Their origins are subject to much debate in recent literature because their masses are far below the typical mass where core collapse is expected to occur. We present the first confirmed evidence that brown dwarfs undergo a phase of molecular outflow that is typical of young stars. Using the Submillimeter Array, we have obtained a map of a bipolar molecular outflow from a young brown dwarf. We estimate an outflow mass of 1.6 x 10^-4 M_Sun and a mass-loss rate of 1.4 x 10^-9 M_Sun. These values are over two orders of magnitude smaller than the typical ones for T Tauri stars. From our millimiter continuum data and our own analysis of Spitzer infrared photometry, we estimate that the brown dwarf has a disk with a mass of 8 x 10^-3 M_Sun and an outer disk radius of 80 AU. Our results demonstrate that the bipolar molecular outflow operates down to planetary masses, occurring in brown dwarfs as a scaled-down version of the universal process seen in young stars.Comment: accepted by ApJ Letter

Magnetic fields in M dwarfs: rapid magnetic field variability in EV Lac

We report here our spectropolarimetric observations obtained using the Espadons/CFHT high resolution spectrograph of two M dwarf stars which standard models suggest are fully convective: EV Lac (M3.5) and HH And (M5.5). The difference in their rotational velocity makes them good targets to study the dependence of the magnetic field topology in M dwarfs on rotation. Our results reveal some aspects of the field topology in EV Lac and HH And. We measured mean longitudinal magnetic field strengths (Bz) in EV Lac ranging from 18+-3 G to -40+-3 G. The Bz variations are seen to occur in a timescale of less than 50 minutes, significantly shorter than the rotation period, and are not due to a flaring event. We discuss some formation scenarios of the Zeeman signatures found in EV Lac. For HH And we could not detect circular polarization and thus we place an upper limit to Bz of 5 G.Comment: Accepted by ApJ Letter