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

Combined Pre-Supernova Alert System with Kamland and Super-Kamiokande

International audiencePreceding a core-collapse supernova, various processes produce an increasing amount of neutrinos of all flavors characterized by mounting energies from the interior of massive stars. Among them, the electron antineutrinos are potentially detectable by terrestrial neutrino experiments such as KamLAND and Super-Kamiokande via inverse beta decay interactions. Once these pre-supernova neutrinos are observed, an early warning of the upcoming core-collapse supernova can be provided. In light of this, KamLAND and Super-Kamiokande have been monitoring pre-supernova neutrinos since 2015 and 2021, respectively. Recently, we performed a joint study between KamLAND and Super-Kamiokande on pre-supernova neutrino detection. A pre-supernova alert system combining the KamLAND detector and the Super-Kamiokande detector is developed and put into operation, which can provide a supernova alert to the astrophysics community. Fully leveraging the complementary properties of these two detectors, the combined alert is expected to resolve a pre-supernova neutrino signal from a 15 M$_{\odot}$ star within 510 pc of the Earth, at a significance level corresponding to a false alarm rate of no more than 1 per century. For a Betelgeuse-like model with optimistic parameters, it can provide early warnings up to 12 hours in advance

Combined Pre-Supernova Alert System with Kamland and Super-Kamiokande

International audiencePreceding a core-collapse supernova, various processes produce an increasing amount of neutrinos of all flavors characterized by mounting energies from the interior of massive stars. Among them, the electron antineutrinos are potentially detectable by terrestrial neutrino experiments such as KamLAND and Super-Kamiokande via inverse beta decay interactions. Once these pre-supernova neutrinos are observed, an early warning of the upcoming core-collapse supernova can be provided. In light of this, KamLAND and Super-Kamiokande have been monitoring pre-supernova neutrinos since 2015 and 2021, respectively. Recently, we performed a joint study between KamLAND and Super-Kamiokande on pre-supernova neutrino detection. A pre-supernova alert system combining the KamLAND detector and the Super-Kamiokande detector is developed and put into operation, which can provide a supernova alert to the astrophysics community. Fully leveraging the complementary properties of these two detectors, the combined alert is expected to resolve a pre-supernova neutrino signal from a 15 M$_{\odot}$ star within 510 pc of the Earth, at a significance level corresponding to a false alarm rate of no more than 1 per century. For a Betelgeuse-like model with optimistic parameters, it can provide early warnings up to 12 hours in advance