INITIAL ANALYSIS ACTIVITY OF HAYABUSA2-RETURNED SAMPLES FROM C-TYPE NEAREARTH ASTEROID (162173) RYUGU

Introduction: The JAXA's asteroid explorer Hayabusa2 investigated Cb-type near-Earth asteroid (162173) Ryugu from June 2018 to November 2019 [e.g., 1-3], during which the spacecraft made two touchdown operations onto the asteroid surface for sample collection with projectile shooting [4-8]. The spacecraft returned its reentry capsule to the Earth on December 6, 2020 [8, 9]. The mass of the returned samples was ~5 grams in total;~3 grams from the first touchdown site and ~2 grams from the second touchdown site [9]. At Institute of Space and Astronautical Science (ISAS), JAXA, particles larger than ~1 mm in size were individually photographed, weighed, and investigated spectroscopically inside the nitrogen-filled chamber system. Particles < 1mm were inspected in a sample dish as bulk aggregates. The initial characterization phase of the returned sample shows that it well represents the finding from spacecraft investigation of the asteroid surface [8-10]. Initial Analysis: After the first six-month of initial description at ISAS, ~300 mg of returned samples (~6 % of total mass) were allocated to the Hayabusa2 initial analysis team in June 2021 for one-year priority analysis led by the Hayabusa2 mission [11]. The number of allocated particles larger than 1 mm were 11 from the first touchdown site (Chamber A grains) and 11 from the second touchdown site (Chamber C grains). Ten sets of aggregate samples, consisting of particles smaller than 1 mm, were also allocated (5 from Chamber A and 5 from Chamber C). To characterize the Ryugu sample and to maximize the science output of the Hayabusa2 mission, the initial analysis team consisted of six sub-teams: Chemistry [12], Mineralogy and Petrology for coarse grains [13], Mineralogy and Petrology for fine grains [14], Volatiles [15], Macromolecular Organics [16], and Soluble Organic Matter [17]. The overall analysis activity went smoothly thanks to the dedication and hard work of the team in spite of challenges presented by a lack of in-person communication during the COVID-19 pandemic. What is Ryugu? All the results from the initial analysis are interpreted to support the hypothesis that Ryugu comes from a parent body of the most chemically primitive CI chondrites (least fractionated from the Sun's elemental abundance) [12-17]. Ryugu's volatile and organic contents are highest compared to the meteorites in our collections except for micrometeorites and interplanetary dust particles [15-17]. Because C-type asteroids are a major group of asteroids, the close relation of Ryugu to the rarest type of chondrites (CI) suggests that the Earth's atmosphere works an effective filter for the influx of fragile meteorites, resulting in a biased sampling of meteorites on the ground. A notable mineralogical difference of Ryugu samples from CI chondrites [12-14] indicates that all CI chondrites recovered on Earth experienced significant terrestrial weathering since their fall. The Hayabusa spacecraft retuned surface particles from S-type asteroid (25143) Itokawa in 2010, which was found to be a parent body of equilibrated LL ordinary chondrites [18, 19]. Therefore S-type asteroids and C-type asteroids are likely to be composed of the non-carbonaceous (NC) and carbonaceous chondrite (CC) group materials, representing isotopically dichotomous components in the early Solar System [20]. Coexistence of S- and C-type asteroids in the present main belt thus requires small body migration in the (early) Solar System, likely caused by migration of giant planets [21]. Comparison of Ryugu samples with the sample from B-type asteroid (101955) Bennu [22] will further constrain the dynamical and chemical evolution of small bodies and the (early) Solar System. [ FROM AUTHOR] Copyright of Meteoritics & Planetary Science is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

Association between Decreased Social Participation and Depressive Symptom Onset among Community-Dwelling Older Adults: A Longitudinal Study during the COVID-19 Pandemic.

OBJECTIVES: The coronavirus disease (COVID-19) pandemic has imposed restrictions on people's social behavior. However, there is limited evidence regarding the relationship between changes in social participation and depressive symptom onset among older adults during the pandemic. We examined the association between changes in social participation and the onset of depressive symptoms among community-dwelling older adults during the COVID-19 pandemic. DESIGN: This was a longitudinal study. SETTING: Communities in Minokamo City, a semi-urban area in Japan. PARTICIPANTS: We recruited community-dwelling older adults aged ≥ 65 years using random sampling. Participants completed a questionnaire survey at baseline (March 2020) and follow-up (October 2020). MEASUREMENTS: Depressive symptoms were assessed using the Two-Question Screen. Based on their social participation status in March and October 2020, participants were classified into four groups: "continued participation," "decreased participation," "increased participation," and "consistent non-participation." RESULTS: A total of 597 older adults without depressive symptoms at baseline were analyzed (mean age = 79.8 years; 50.4% females). Depressive symptoms occurred in 20.1% of the participants during the observation period. Multivariable Poisson regression analysis showed that decreased social participation was significantly associated with the onset of the depressive symptoms, compared to continued participation, after adjusting for all covariates (incidence rate ratio = 1.59, 95% confidence interval = 1.01-2.50, p = 0.045). CONCLUSION: Older adults with decreased social participation during the COVID-19 pandemic demonstrated a high risk of developing depressive symptoms. We recommend that resuming community activities and promoting the participation of older adults, with sufficient consideration for infection prevention, are needed to maintain mental health among older adults.

Coronavirus pandemic-medical law and ethical issues in the United States

This article examines Corona virus (Covid-19) originated in Wuhan, China in late 2019 and appeared in early January in the USA and California. During early March 2020, the virus spread rapidly throughout the USA. According to Governor Andrew Cuomo, the mass infection first spread to Europe and arrived in New York City (NYC), overwhelming healthcare facilities. The probability of California experiencing a similar situation to NYC was greatly diminished by Governor Gavin Newsom’s issuance of the Stay at Home order, issued on March 16, 2020, which encouraged businesses to continue adapting their offices to an online format and workers to work remotely. Another medical law and ethics issue is the racial hate and discrimination towards the Asian community. Discriminatory remarks such as “Go back to China” to Asians has been overheard. The Center for Disease Control (CDC) guidance was issued in May 2020 stating, “while some communities will progress sequentially through the reopening phases, there is the possibility of recrudescence in some areas.” “Given the potential for a rebound in the number of cases or level of community transmission, a low threshold for reinstating more stringent mitigation standards will be essential. A number of lessons can be learned from this event. A pandemic requires national and international coordination, planning and implementation. Until the global infection is eradicated, second waves of infection will likely surge.”. © 2020, William S. Hein & Co., Inc.. All rights reserved.