Detection of the Far-infrared [O III] and Dust Emission in a Galaxy at Redshift 8.312: Early Metal Enrichment in the Heart of the Reionization Era

We present the Atacama Large Millimeter/submillimeter Array (ALMA) detection of the [O III] 88 $\mu$m line and rest-frame 90 $\mu$m dust continuum emission in a Y-dropout Lyman break galaxy (LBG), MACS0416_Y1, lying behind the Frontier Field cluster MACS J0416.1-2403. This [O III] detection confirms the LBG with a spectroscopic redshift of $z = 8.3118 \pm 0.0003$, making this object one of the furthest galaxies ever identified spectroscopically. The observed 850 $\mu$m flux density of $137 \pm 26$ $\mu$Jy corresponds to a de-lensed total infrared (IR) luminosity of $L_{\rm IR} = (1.7 \pm 0.3) \times 10^{11} L_{\odot}$ if assuming a dust temperature of $T_{\rm dust} = 50$ K and an emissivity index of $\beta = 1.5$, yielding a large dust mass of $4 \times 10^6 M_{\odot}$. The ultraviolet-to-far IR spectral energy distribution modeling where the [O III] emissivity model is incorporated suggests the presence of a young ($\tau_{\rm age} \approx 4$ Myr), star-forming (SFR $\approx 60 M_{\odot}$ yr$^{-1}$), moderately metal-polluted ($Z \approx 0.2 Z_{\odot}$) stellar component with a mass of $M_{\rm star} = 3 \times 10^8 M_{\odot}$. An analytic dust mass evolution model with a single episode of star-formation does not reproduce the metallicity and dust mass in $\tau_{\rm age} \approx 4$ Myr, suggesting a pre-existing evolved stellar component with $M_{\rm star} \sim 3 \times 10^9 M_{\odot}$ and $\tau_{\rm age} \sim 0.3$ Gyr as the origin of the dust mass.Comment: Accepted by ApJ. 18 pages, 10 figures, 5 table

Mechanisms of spindle bipolarity establishment in acentrosomal human cells

Centrosomes are not absolutely essential for cell division; acentrosomal bipolar spindles can be established in oocytes and centrosome-eliminated somatic cells. However, the detailed mechanisms describing how spindle bipolarity is established without centrosomes are not completely understood. We have recently demonstrated that in acentrosomal human cells, nuclear mitotic apparatus protein (NuMA) assemblies-mediated microtubule asters and EG5 promote spindle bipolarization in early mitosis

Airborne transmission during short-term events under stratum ventilation

Past studies on airborne spread of expiratory droplet nuclei between occupants were focused on long-term exposure under steady-state conditions. However, exposure during short-term events can be widely found in practice, e.g. medical examination or short meeting. Airborne transmission during short-term events under stratum ventilation was examined experimentally in this study. Two breathing thermal manikins were employed to simulate a standing infected person and a standing exposed person. The manikins were placed face-to-face and face-to-back to reproduce the exposure conditions with the highest and the lowest risk, respectively. Tracer gas was dosed into the air exhaled by the “infected” manikin to simulate the droplet nuclei. A newly developed average exposure index was used to evaluate the exposure risk. The time-averaged exposure index increases over time, but the increasing rate depends strongly on the duration of exposure time, e.g., the exposure index increases much faster during the first 5 minutes than during the period after 5 minutes. The exposure index during short-term events does not always decrease with the increase of separation distance. These findings imply that the control measures formulated based on steady-state conditions are not necessarily effective to short-term events

Measurement of Face-touching Frequency in a Simulated Train

Contact behavior in a public space influences the risk of contact infection because public spaces have many environmental surfaces contaminated with pathogens. It is useful for risk reduction to examine the factor of infection risk among behaviors. In the present study, a video monitoring survey was conducted in a simulated cabin of a commuter train, we had built, to investigate the relationship between face-touching frequencies and individual attributes. As a result, the average face-touching frequency was 17.8 times per hour. Of all face touches, mucosal contact was 42.2%. Focusing on the sex, the face-touching frequency was significantly higher for the males than for the females. Focusing on the skin condition, the face-touching frequency of those who did not wear makeup was significantly higher than that of those who did. The significant sex differences may depend on the makeup. Focusing on pollution awareness, higher pollution awareness related to lower frequency. Thus, by improving pollution awareness of the environmental surfaces in public spaces, it is possible to reduce effectively face-touching frequency and, hence, infection risk

Evaluation of Short-Distance Airborne Infection Risk Using a Cough Generator

Short-distance airborne infections are often thought to occur by large droplets or direct contact. Recent studies have investigated the phenomenon of short-range airborne infection. In this study, the effect of relative humidity and short-distance exposure to cough droplet nuclei were evaluated. The evaluation model for infection risk was designed based on experimental data and previous studies and included sampling efficiency and virus survival rate. As observed in the comparison between short-range exposure and long-range exposure, the short-range exposure to the droplet nuclei by one cough was equivalent to a long-range exposure of several seconds to, depending on the number of ventilations, even for a momentary high-concentration exposure. This suggests the possibility of an infection risk corresponding to the receiving condition. Since short-range exposure and long-range exposure have different factors affecting the risk of infection, it is suggested that effective infection control should be selected for each condition. The risk of infection due to long-range exposure is considered to be sufficiently reduced to that of a single cough if the building meets the necessary number of ventilations. It was suggested that the influence of relative humidity on infection risks is smaller than other factors such as ventilation