Science learning should be accessible for all learners including students with visually impaired (VI). Students with VI apparently have the same cognitive abilities range and can master higher-order ...science concept as well. The purpose of this study is to explain that students with VI can learn science well if there is the right learning support tool by in-depth literature review. This in-depth literature review uses the following steps: selection of the articles, analysis the studies and categorization of the articles. A total of seventeen journal articles from the year of 2009-2018 written in English on the topic of science learning for students with VI that divided based on how do the students with VI learn and teaching and learning science to students with VI. This literature was collected via the ERIC database and the Google Scholar website. Based on this literature reviews, students with VI can learn science well if there is a proper support tool for them to learn. If the teachers are able to apply the right learning model and are supported with good facilities such as orientation and movement, tactile and kinesthetic learning, auditory learning and accommodations, and assistive technology, it is possible that students with VI will be able to learn about science very well.
Gamma-ray bursts (GRBs) are flashes of high-energy radiation arising from energetic cosmic explosions. Bursts of long (greater than two seconds) duration are produced by the core-collapse of massive ...stars
, and those of short (less than two seconds) duration by the merger of compact objects, such as two neutron stars
. A third class of events with hybrid high-energy properties was identified
, but never conclusively linked to a stellar progenitor. The lack of bright supernovae rules out typical core-collapse explosions
, but their distance scales prevent sensitive searches for direct signatures of a progenitor system. Only tentative evidence for a kilonova has been presented
. Here we report observations of the exceptionally bright GRB 211211A, which classify it as a hybrid event and constrain its distance scale to only 346 megaparsecs. Our measurements indicate that its lower-energy (from ultraviolet to near-infrared) counterpart is powered by a luminous (approximately 10
erg per second) kilonova possibly formed in the ejecta of a compact object merger.
ABSTRACT We report the results of our observing campaign on GRB 140903A, a nearby (z = 0.351) short-duration (T90 ∼ 0.3 s) gamma-ray burst discovered by Swift. We monitored the X-ray afterglow with ...Chandra up to 15 days after the burst and detected a steeper decay of the X-ray flux after tj 1 day. Continued monitoring at optical and radio wavelengths showed a similar decay in flux at nearly the same time, and we interpret it as evidence of a narrowly collimated jet. By using the standard fireball model to describe the afterglow evolution, we derive a jet opening angle θj 5° and a collimation-corrected total energy release E 2 erg. We further discuss the nature of the GRB progenitor system. Three main lines disfavor a massive star progenitor: the properties of the prompt gamma-ray emission, the age and low star formation rate of the host galaxy, and the lack of a bright supernova. We conclude that this event likely originated from a compact binary merger.
It is well known that adult humans detect snakes as targets more quickly than flowers as the targets and that how rapidly they detect a snake picture does not differ whether the images are in color ...or gray-scale, whereas they find a flower picture more rapidly when the images are in color than when the images are gray-scale. In the present study, a total of 111 children were presented with 3-by-3 matrices of images of snakes and flowers in either color or gray-scale displays. Unlike the adults reported on previously, the present participants responded to the target faster when it was in color than when it was gray-scale, whether the target was a snake or a flower, regardless of their age. When detecting snakes, human children appear to selectively attend to their color, which would contribute to the detection being more rapidly at the expense of its precision.
To evaluate the use of deep-learning-based image reconstruction (DLIR) algorithms in dynamic contrast-enhanced computed tomography (CT) of the abdomen, and to compare the image quality and lesion ...conspicuity among the reconstruction strength levels.
This prospective study included 59 patients with 373 hepatic lesions who underwent dynamic contrast-enhanced CT of the abdomen. All images were reconstructed using four reconstruction algorithms, including 40% adaptive statistical iterative reconstruction–Veo (ASiR-V) and DLIR at low, medium, and high-strength levels (DLIR-L, DLIR-M, and DLIR-H, respectively). The signal-to-noise ratio (SNR) of the abdominal aorta, portal vein, liver, pancreas, and spleen and the lesion-to-liver contrast-to-noise ratio (CNR) were calculated and compared among the four reconstruction algorithms. The diagnostic acceptability was qualitatively assessed and compared among the four reconstruction algorithms and the conspicuity of hepatic lesions was compared between <5 and ≥5 mm lesions.
The SNR of each anatomical structure (p<0.0001) and CNR (p<0.0001) were significantly higher in DLIR-H than the other reconstruction algorithms. Diagnostic acceptability was significantly better in DLIR-M than the other reconstruction algorithms (p<0.0001). The conspicuity of hepatic lesions was highest when using 40% ASiR-V and tended to lessen as the reconstruction strength level was getting higher in DLIR, especially in <5 mm lesions; however, all hepatic lesions could be detected.
DLIR improved the SNR, CNR, and image quality compared with 40% ASiR-V, while making it possible to decrease lesion conspicuity using higher reconstruction strength.
•The DLIR demonstrated a significant noise reduction and improved image quality.•The DLIR could be used as a surrogate for the IR method.•Higher strength of the DLIR was possible to decrease lesion conspicuity.
ABSTRACT
We present a detailed multiwavelength analysis of two short gamma-ray bursts (sGRBs) detected by the Neil Gehrels Swift Observatory: GRB 160624A at $z$ = 0.483 and GRB 200522A at $z$ = ...0.554. These sGRBs demonstrate very different properties in their observed emission and environment. GRB 160624A is associated with a late-type galaxy with an old stellar population (≈3 Gyr) and moderate ongoing star formation (≈1 M⊙ yr−1). Hubble and Gemini limits on optical/near-infrared emission from GRB 160624A are among the most stringent for sGRBs, leading to tight constraints on the allowed kilonova properties. In particular, we rule out any kilonova brighter than AT2017gfo, disfavouring large masses of wind ejecta (≲0.03 M⊙). In contrast, observations of GRB 200522A uncovered a luminous (LF125W ≈ 1042 erg s−1 at 2.3 d) and red (r − H ≈ 1.3 mag) counterpart. The red colour can be explained either by bright kilonova emission powered by the radioactive decay of a large amount of wind ejecta (0.03 M⊙ ≲ M ≲ 0.1 M⊙) or moderate extinction, E(B − V) ≈ 0.1−0.2 mag, along the line of sight. The location of this sGRB in the inner regions of a young (≈0.1 Gyr) star-forming (≈2−6 M⊙ yr−1) galaxy and the limited sampling of its counterpart do not allow us to rule out dust effects as contributing, at least in part, to the red colour.
X-Ray Transients Observed with MAXI Kawai, N.
Proceedings of the International Astronomical Union,
11/2017, Letnik:
14, Številka:
S339
Journal Article
Recenzirano
MAXI (Monitor of All-sky X-ray Image) is an astronomical mission onboard the International Space Station. It started observations in August 2009. The Gas Slit Camera of MAXI is sensitive to X-rays in ...the energy range 2–30 keV. Most of the sky is scanned every 90 min with the orbital revolution of the ISS. With this unbiased monitoring, MAXI has detected numerous outbursts from known and unknown X-ray sources. MAXI discovered 18 X-ray novæ in seven years, including seven neutron star binaries, six black hole binaries (+candidates) and four unidentified sources. Other results include detections of superluminous stellar flares, a super-Eddington luminous flare from a white dwarf+Be Star binary near the SMC, and monitoring of recurrent outbursts from Be neutron-star binaries. Variations in X-ray-bright AGNs such as Cen A and Mrk 421 have been also monitored. This talk presented the highlights of the MAXI observations of variable sources, including the search for X-ray counterparts of gravitational-wave events.
We present the earliest X-ray observations of the 2018 outburst of XTE J1810−197, the first outburst since its 2003 discovery as the prototypical transient and radio-emitting anomalous X-ray pulsar ...(AXP). The Monitor of All-sky X-ray Image (MAXI) detected XTE J1810−197 immediately after a November 20-26 visibility gap, contemporaneous with its reactivation as a radio pulsar, first observed on December 8. On December 13 the Nuclear Spectroscopic Telescope Array (NuSTAR) detected X-ray emission up to at least 30 keV, with a spectrum well-characterized by a blackbody plus power-law model with temperature kT = 0.74 0.02 keV and photon index Γ = 4.4 0.2 or by a two-blackbody model with kT = 0.59 0.04 keV and kT = 1.0 0.1 keV, both including an additional power-law component to account for emission above 10 keV, with Γh = −0.2 1.5 and Γh = 1.5 0.5, respectively. The latter index is consistent with hard X-ray flux reported for the nontransient magnetars. In the 2-10 keV bandpass, the absorbed flux is 2 × 10−10 erg s−1 cm−2, a factor of 2 greater than the maximum flux extrapolated for the 2003 outburst. The peak of the sinusoidal X-ray pulse lags the radio pulse by 0.13 cycles, consistent with their phase relationship during the 2003 outburst. This suggests a stable geometry in which radio emission originates on magnetic field lines containing currents that heat a spot on the neutron star surface. However, a measured energy-dependent phase shift of the pulsed X-rays suggests that all X-ray emitting regions are not precisely coaligned.
In order to study seismo-mechanochemical processes, two kinds of shock compression experiments – the recovery and the in-situ VISAR (velocity interferometer system for any reflector) experiments – ...were performed, using a single crystal of forsteritic olivine and a single-stage powder propellant gun. The generated peak shock pressures were 31.1 GPa for both the recovery and the VISAR experiments. Many shear planes were generated in the olivine crystal. The VISAR experiment revealed detailed time profiles for the particle and shock wave velocities during the compression and yielded the Hugoniot elastic limit (HEL) of the olivine to be 7.44 GPa. We observed, in one recovered sample, a clear local melting occurring along a shear plane. The microstructural observations of the shear plane and its walls using a field-emission scanning electron microscopy (SEM) and an analytical transmission electron microscopy (ATEM) revealed that plastically-deformed olivine was pulverized into a few hundred-nanometer size particle assemblages within a few-micrometers narrow zone along the shear plane and, locally have partially melted. Moreover, injection veins filled with olivine melt were found in the wall of the same shear plane. It was shown from the estimate of the critical resolved shear stress (CRSS) along the shear planes and the inferred slip velocity using the Hugoniot elastic limit (HEL) data that the power generated by the friction was large enough for melting to occur in the olivine. The whole process occurred in a time scale <0.6 microsecond. Pulverization (comminution) before melting is considered to be a common phenomenon in the formation of pseudotachylytes and in dynamically expanding seismic faults upon earthquakes.
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•Shock compression experiments were performed using a forsterite single crystal and a powder propellant gun.•Particle velocity profile on the olivine surface was obtained by laser in situ measurement.•Many shear bands were generated in the olivine, where a clear local melting was observed.•It was found out that plastic deformation and pulverization took place before melting.•Pulverization before melting may be a common phenomenon in co-seismic faults in earthquakes.
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