ARICA: Demonstration of a Real-time Gamma-Ray Bursts Alert System using the Commercial Satellite Networks

We demonstrate the real-time alert system of the transient astronomical sources such as cosmic gamma-ray bursts (GRBs) using two commercial satellite network devices. One is the Iridium’s Short Burst Data (SBD) and the other is the Globalstar’s STX-3. Although these satellite communication devices have been used in the space environment, it still needs to verify whether the network can be used as a GRB alert system. We are currently developing a 1U CubeSat called AGU Remote Innovative CubeSat Alert system (ARICA) which contains both SBD and STX-3 to demonstrate the real-time GRB alert system. The ARICA has been selected as the JAXA Innovative Satellite Technology Demonstration-2 and scheduled to be launched in the Japanese fiscal year 2021

Flight Model Development of the AGU Remote Innovative CubeSat Alert System - ARICA

We present the flight model development of the 1U CubeSat, AGU Remote Innovative CubeSat Alert system (ARICA), which is scheduled to be launched in the Japanese fiscal year 2021 as the JAXA Innovative Satellite Technology Demonstration-2 project. The main goal of ARICA is to demonstrate the real-time alert system of the transient astronomical sources using commercial satellite network devices. The development of the flight components has been finished in April 2021. The thermal vacuum test was conducted at the end of April 2021. The vibration and shock tests were performed in May 2021. We are currently in the final stage of the development of ARICA to be ready for launch

Estimation of the Number of Sprites Observed over Japan in 5.5 Years Using Lightning Data

This study is based on 5.5 years of continuous observation of sprites from Sagamihara, Japan. Up to February 2022, we detected 537 sprites and found that the most significant number of sprites were observed during the winter (303 sprites); on the other hand, there were only 46 sprites in summer. The hourly distribution of the number of observed sprites peaked at midnight JST (15:00 and 16:00 UTC). To understand the seasonal and the hourly distribution of sprites, we estimate the number of sprites considering the energy and the polarity of lightning, the temporal changes of surrounding environments of sprites, and the conditions for generating sprites. We found that the energy of lightning, the monthly ratio of a positive cloud-to-ground discharge, and the hourly change in the electron number density are essential factors to match the observed sprite distributions

The Promotional Effect of GW4869 on C. albicans Invasion and Cellular Damage in a Murine Model of Oral Candidiasis

Candida albicans (C. albicans) is one of the most common fungi in the human body; it is an opportunistic pathogen and can cause candidiasis. Extracellular vesicles (EVs) derived from the host cells have a potentially protective effect against pathogens and can be developed as vaccine formulations. GW4869 can inhibit the production and release of EVs. Previous studies have indicated that GW4869 can alter the immune and inflammatory responses of the host. However, the effect of GW4869 on Candida infection and the anti-Candida response of the host has not been investigated. We evaluated the effect of GW4869 on C. albicans invasion, biofilm formation, and cellular damage in a murine model of oral candidiasis. In this study, C. albicans-infected mice were injected with or without GW4869. The results proven by macroscopic, microscopic, and ultramicroscopic methods showed that GW4869 treatment exacerbated the oral candidiasis of mice, promoted C. albicans invasion and biofilm formation, and aggravated oral mucosal inflammation and cellular ultrastructural damage. The results are beneficial in the further exploration of the immune mechanism of C. albicans infection

Extracellular vesicle‐packaged mitochondrial disturbing miRNA exacerbates cardiac injury during acute myocardial infarction

Abstract Mounting evidence suggests that extracellular vesicles (EVs) are effective communicators in biological signalling in cardiac physiology and pathology. However, the role of EVs in cardiac injury, particularly in ischemic myocardial scenarios, has not been fully elucidated. Here, we report that acute myocardial infarction (AMI)‐induced EVs can impair cardiomyocyte survival and exacerbate cardiac injury. EV‐encapsulated miR‐503, which is enriched during the early phase of AMI, is a critical molecule that mediates myocardial injury. Functional studies revealed that miR‐503 promoted cardiomyocyte death by directly binding to peroxisome proliferator‐activated receptor gamma coactivator‐1β (PGC‐1β) and a mitochondrial deacetylase, sirtuin 3 (SIRT3), thereby triggering mitochondrial metabolic dysfunction and cardiomyocyte death. Mechanistically, we identified endothelial cells as the primary source of miR‐503 in EVs after AMI. Hypoxia induced rapid H3K4 methylation of the promoter of the methyltransferase‐like 3 gene (METTL3) and resulted in its overexpression. METTL3 overexpression evokes N6‐methyladenosine (m6A)‐dependent miR‐503 biogenesis in endothelial cells. In summary, this study highlights a novel endogenous mechanism wherein EVs aggravate myocardial injury during the onset of AMI via endothelial cell‐secreted miR‐503 shuttling