No abstract

We report that the optical polarization in the afterglow of GRB 091208B is measured at t = 149 − 706 s after the burst trigger, and the polarization degree is P = 10.4% ± 2.5%. The optical light curve at this time shows a power-law decay with index −0.75 ± 0.02, which is interpreted as the forward shock synchrotron emission, and thus this is the first detection of the early-time optical polarization in the forward shock (rather than that in the reverse shock reported by (Steele et al. 2009)). This detection disfavors the afterglow model in which the magnetic fields in the emission region are random on the plasma skin depth scales, such as amplified by the plasma instabilities, e.g., Weibel instability. We suggest that the fields are amplified by the magnetohydrodynamic instabilities, which would be tested by future observations of the temporal changes of the polarization degrees and angles for other bursts.

Chiral discrimination of saturated hydrocarbons has been very difficult to establish, or has not been possible at all. The first chiral discrimination of cryptochiral 5-ethyl-5-propylundecane 1, that is, (n-butyl)ethyl(n-hexyl)(n-propyl)methane, a chiral saturated quaternary hydrocarbon, which is known to exhibit practically no detectable value of optical rotation between 280 and 580 nm, has been accomplished by asymmetric autocatalysis of pyrimidyl alkanol. The absolute configuration of 1 has been determined. In the presence of (R)- or (S)-1, the reaction between pyrimidine-5-carbaldehyde and diisopropylzinc affords (S)- and (R)-pyrimidyl alkanol with 91-97% ee, respectively. Thus, asymmetric autocatalysis serves as a powerful tool for the chiral discrimination of saturated hydrocarbons.

We presented optical and near-infrared multi-band linear polarimetry of the highly reddened Type Ia SN 2014J appeared in M82. SN 2014J exhibits large polarization at shorter wavelengths, e.g., 4.8% in B band, and the polarization decreases rapidly at longer wavelengths, with the position angle of the polarization remaining at approximately 40 • over the observed wavelength range. These polarimetric properties suggest that the observed polarization is likely to be caused predominantly by the interstellar dust within M82. Further analysis shows that the polarization peaks at a wavelengths much shorter than those obtained for the Galactic dust. The wavelength dependence of the polarization can be better described by an inverse power law rather than by Serkowski law for Galactic interstellar polarization. These suggests that the nature of the dust in M82 may be different from that in our Galaxy, with polarizing dust grains having a mean radius of < 0.1 µm .

To prevent cognitive decline, non-pharmacological therapies such as reminiscence for mild cognitive impairment (MCI) are required, however, the use of nursing homes was limited due to coronavirus disease 2019 (COVID-19). Therefore, the demand for remote-care is increasing. We hypothesized that immersive virtual reality (iVR) could be used more effectively than conventional reminiscence for anxiety. We first examined the effectiveness and safety of reminiscence using iVR (iVR reminiscence session) in patients with MCI. After COVID-19 imposed restriction on visiting nursing homes, we conducted online iVR reminiscence session (remote iVR reminiscence session) and compared its effectiveness with that of interpersonal iVR reminiscence session (face-to-face iVR reminiscence session). The results of two elderly with MCI suggested that iVR reminiscence could reduce anxiety and the burden of care without serious side effects. The effects of remote iVR reminiscence might be almost as effective as those of face-to-face one.