An Analysis Using Eye-Mark Recorder of the Effectiveness of Presentation Methods for E-learning

Non

Primordial Black Holes for the LIGO Events in the Axion-like Curvaton Model

We revise primordial black hole (PBH) formation in the axion-like curvaton model and investigate whether PBHs formed in this model can be the origin of the gravtitational wave (GW) signals detected by the Advanced LIGO. In this model, small-scale curvature perturbations with large amplitude are generated, which is essential for PBH formation. On the other hand, large curvature perturbations also become a source of primordial GWs by their second-order effects. Severe constraints are imposed on such GWs by pulsar timing array (PTA) experiments. We also check the consistency of the model with these constraints. In this analysis, it is important to take into account the effect of non-Gaussianity, which is generated easily in the curvaton model. We see that, if there are non-Gaussianities, the fixed amount of PBHs can be produced with a smaller amplitude of the primordial power spectrum.Comment: 25 pages, 8 figure

デュアル・チャンネル・モデルに基づくeラーニング・マルチメディア教材におけるポインタ提示の効果分析

電気通信大学200

Slowed response to peripheral visual stimuli during strenuous exercise

Recently, we proposed that strenuous exercise impairs peripheral visual perception because visual responses to peripheral visual stimuli were slowed during strenuous exercise. However, this proposal was challenged because strenuous exercise is also likely to affect the brain network underlying motor responses. The purpose of the current study was to resolve this issue. Fourteen participants performed a visual reaction-time (RT) task at rest and while exercising at 50% (moderate) and 75% (strenuous) peak oxygen uptake. Visual stimuli were randomly presented at different distances from fixation in two task conditions: the Central condition (2° or 5° from fixation) and the Peripheral condition (30° or 50° from fixation). We defined premotor time as the time between stimulus onset and the motor response, as determined using electromyographic recordings. In the Central condition, premotor time did not change during moderate (167 ± 19 ms) and strenuous (168 ± 24 ms) exercise from that at rest (164 ± 17 ms). In the Peripheral condition, premotor time significantly increased during moderate (181 ± 18 ms, P < 0.05) and strenuous exercise (189 ± 23 ms, P < 0.001) from that at rest (173 ± 17 ms). These results suggest that increases in Premotor Time to the peripheral visual stimuli did not result from an impaired motor-response network, but rather from impaired peripheral visual perception. We conclude that slowed response to peripheral visual stimuli during strenuous exercise primarily results from impaired visual perception of the periphery

Preparation of Some α-Substituted Cyclopropanecarboxylic Acids via Dichlorocarbene

Some α, β-unsaturated esters (1), including trans-crotonate, trans-α-methoxycrotonate, irans-α-fluorocrotonate, trans-cinnamate, trans-α-chlorocinnamate, cis- and trans-α-fluorocinnamates, fumarate, and maleate, were allowed to react with dichlorocarbene, generated by the thermal decomposition of sodium trichloroacetate at 120-160°C, to give the corresponding β, β-dichlorocyclopropanecarboxylates (2) in fair to good yields (38-88%). The additions of dichlorocarbene to these esters were stereospecific. A similar reaction of n-butyl acrylate gave only a very low yield (6%) of the dichlorocarbene adduct, probably because of the accompanying polymerization of the starting ester. The reduction of 1-unsubstituted or 1-methoxysubstituted 2, 2-dichloro-3-methylcyclopropanecarboxylate with tri-n-butyltin hydride at 90°C yielded both the completely reduced (3) and the partially reduced esters (4 and 5). That of 1-fluoro-substituted ester gave only the completely reduced product. These cyclopropanecarboxylates (2 and 3) were hydrolyzed with potassium hydroxide to give the corresponding free acids (6 and 7) in good yields (72-92%). The properties (bp, mp, nᴅ, pmr spectral data, etc.) of the cyclopropanecarboxylic acids and esters thus prepared are described

Intersubband absorption linewidth in GaAs quantum wells due to scattering by interface roughness, phonons, alloy disorder, and impurities

We calculate the intersubband absorption linewidth in quantum wells (QWs) due to scattering by interface roughness, LO phonons, LA phonons, alloy disorder, and ionized impurities, and compare it with the transport energy broadening that corresponds to the transport relaxation time related to electron mobility. Numerical calculations for GaAs QWs clarify the different contributions of each individual scattering mechanism to absorption linewidth and transport broadening. Interface roughness scattering contributes about an order of magnitude more to linewidth than to transport broadening, because the contribution from the intrasubband scattering in the first excited subband is much larger than that in the ground subband. On the other hand, LO phonon scattering (at room temperature) and ionized impurity scattering contribute much less to linewidth than to transport broadening. LA phonon scattering makes comparable contributions to linewidth and transport broadening, and so does alloy disorder scattering. The combination of these contributions with significantly different characteristics makes the absolute values of linewidth and transport broadening very different, and leads to the apparent lack of correlation between them when a parameter, such as temperature or alloy composition, is changed. Our numerical calculations can quantitatively explain the previously reported experimental results.Comment: 17 pages, including 15 figure

Constraining dark matter annihilation with HSC Low Surface Brightness Galaxies

Searches for dark matter annihilation signals have been carried out in a number of target regions such as the Galactic Center and Milky Way dwarf spheroidal galaxies (dSphs), among a few others. Here we propose low surface brightness galaxies (LSBGs) asnovel targets for the indirect detection of dark matter emission. In particular, LSBGs are known to have very large dark matter contents and be less contaminated by extragalactic gamma-ray sources (e.g., blazars) compared to star forming galaxies. We report on an analysis that uses eight LSBGs (detected by Subaru Hyper Suprime-Cam survey data) with known redshifts to conduct a search for gamma-ray emission at the positions of these new objects in Fermi Large Area Telescope data. We found no excesses of gamma-ray emission and set constraints on the dark matter annihilation cross-section. We exclude (at the 95% C.L.) dark matter scenarios predicting a cross-section higher than 10^-23[cm^3/s] for dark matter particles of mass 10 GeV self-annihilating in the b_b channel. Although this constraint is weaker than the ones reported in recent studies using other targets, we note that in the near future, the number of detections of new LSBGs will increase by a few orders of magnitude. We forecast that with the use of the full catalog of soon-to-be-detected LSBGs the constraint will reach cross-section sensitivities of ~ 3*10^-25 [cm^3/s] for dark matter particles with masses less than 10 GeV.Comment: 19 pages, 6 figures, accepted to JCA