Molecular clouds towards RCW 49 and Westerlund 2; Evidence for cluster formation triggered by cloud-cloud collision

We have made CO(J=2-1) observations towards the HII region RCW 49 and its ionizing source, the rich stellar cluster Westerlund 2 (hereafter Wd2), with the NANTEN2 sub-mm telescope. These observations have revealed that two molecular clouds in velocity ranges of -11 to +9 km/s and 11 to 21 km/s respectively, show remarkably good spatial correlations with the Spitzer IRAC mid-infrared image of RCW 49, as well a velocity structures indicative of localized expansion around the bright central regions and stellar cluster. This strongly argues that the two clouds are physically associated with RCW 49. We obtain a new kinematic distance estimate to RCW 49 and Wd2 of 5.4^{+ 1.1}_{- 1.4} kpc, based on the mean velocity and velocity spread of the associated gas. We argue that acceleration of the gas by stellar winds from Wd2 is insufficient to explain the entire observed velocity dispersion of the molecular gas, and suggest a scenario in which a collision between the two clouds ~4 Myrs ago may have triggered the formation of the stellar cluster.Comment: A version with higher resolution figures is available from http://www.a.phys.nagoya-u.ac.jp/~naoko/research/apjl2009/fur09_rev_highreso.pd

Application of hot spring pool training in outpatients with chronic diseases and its clinical evaluation

1996年4月より6月までの3ヵ月間に,三朝分院内の温泉プールで水泳ないし歩行訓練を受けた内科外来患者は延べ2109例(実数213例)で,外来患者総数(延べ6848例)に対する利用率は30.8%であった｡これらの対象症例について,リハビリテーション受診カードにより,性別,年令別,疾患別の検討を行った｡その結果,性別では女性が多く(72.3%),年齢別では50才以上の患者が多い(80.3%)傾向が見られた｡また,地域別検討では,鳥取県内からの患 者が多い(88.3%)傾向であった。さらに,1996年12月より1997年1月へかけて,アンケート調査を行い(集計数;64例)継続期間,利用回数,効果を感じた期間,効果のあった症状などについて疾患別に比較検討した｡その結果,慢性閉塞性肺疾患を主とした呼吸器疾患では,週に1～2回の利用回数(50.0%)で長期間(3年以上:52.9%)続けている患者が多い傾向であった｡また慢性関節リウマチ,腰痛などの慢性疼痛性疾患では,訓練期間は比較的短期間であっ たが（3年以下:52.9%),利用回数は週に3～5回(38.0%)と多い傾向が見られた。温泉プール訓練では,疾患本来の症状改善に加えて,全身状態の改善,精神的リラックス,気分転換などを感じていることが示唆された｡For three months from April to June in 1996, 2109(30.8%) of 6848 outpatients (the total number) had swimming and walking traning in a hot spring pool. Of the 213 patients (the actual number), the numbers of female patients (72.3%), of patients over the age of 50 (80.3%), and of those coming inside Tottori prefecture (88.3%) were larger in analysis by the consultation cards for rehabillitation. The results of questionnaire from the patients performed from December 1996 to January 1997 demonstrated that patients with chronic respiratory disease had pool training 1 to 2 times a week (50.0%) and for longer term (more than 3 years, 52.9%), and patients with chronic pain disease had the training 3 to 5 times a week (38.0%) and for shoter term (less than 3 years, 61.9%). It was suggested from the results that tha training in a hot spring pool improved subjective and objective symptoms of each disease, and, furthermore, brought about improvement of general condition, psychological relaxation, and a change of feeling

Students' Approach to and Satisfaction with Online Courses in the First Semester of 2020 at Tokushima University

本研究の目的は，学生のオンライン授業に対する満足度を把握し，今後のオンライン授業の質保証に向けた基礎的資料を得ることである。本研究では，学生のオンライン授業に対する満足度に着目し，今後のオンライン授業の質保証について検討した。その結果，本調査対象者においては，1 年生がオンライン授業に対して参加頻度が高いことが把握された。そして，オンライン授業の受講生の満足度は，ライブ型オンライン授業の参加頻度とある程度の関連性があることが示唆された。This study aims to understand students' satisfaction with online classes and to obtain basic data for the quality assurance of online courses in the future. Therefore, in this study, we focused on students' satisfaction with online courses and examined the quality assurance of online classes in the future. As a result, it was found that first-year students participated more frequently in online courses than senior students among the subjects of this study. Furthermore, the results suggest that the degree of satisfaction of students in online courses is related to the frequency of participation in live online courses

The Second Survey of the Molecular Clouds in the Large Magellanic Cloud by NANTEN. II. Star Formation

We studied star formation activities in the molecular clouds in the Large Magellanic Cloud. We have utilized the second catalog of 272 molecular clouds obtained by NANTEN to compare the cloud distribution with signatures of massive star formation including stellar clusters, and optical and radio HII regions. We find that the molecular clouds are classified into three types according to the activities of massive star formation; Type I shows no signature of massive star formation, Type II is associated with relatively small HII region(s) and Type III with both HII region(s) and young stellar cluster(s). The radio continuum sources were used to confirm that Type I GMCs do not host optically hidden HII regions. These signatures of massive star formation show a good spatial correlation with the molecular clouds in a sense they are located within ~100 pc of the molecular clouds. Among possible ideas to explain the GMC Types, we favor that the Types indicate an evolutionary sequence; i.e., the youngest phase is Type I, followed by Type II and the last phase is Type III, where the most active star formation takes place leading to cloud dispersal. The number of the three types of GMCs should be proportional to the time scale of each evolutionary stage if a steady state of massive star and cluster formation is a good approximation. By adopting the time scale of the youngest stellar clusters, 10 Myrs, we roughly estimate the timescales of Types I, II and III to be 6 Myrs, 13 Myrs and 7 Myrs, respectively, corresponding to a lifetime of 20-30 Myrs for the GMCs with a mass above the completeness limit, 5 x 10^4 Msun.Comment: accepted to the Astrophysical Journal Supplement Series. 20 figures and 4 tables. Higher resolution color PDF is found at http://www.a.phys.nagoya-u.ac.jp/~kawamura/research/NANTEN_LMC_2_preprint.pdf (47 pages,32MB

Statistical study of dust properties in LMC molecular clouds

The objective of this paper is to construct a catalog providing the dust properties and the star formation efficiency (SFE) of the molecular clouds in the Large Magellanic Cloud (LMC). We use the infrared (IR) data obtained with the Spitzer telescope as part of the ``Surveying the Agents of a Galaxy's Evolution'' (SAGE) Legacy survey as well as the IRAS data. We also work with extinction (Av) maps of the LMC. A total of 272 molecular clouds have been detected in the LMC in a previous molecular survey, accounting for 230 giant molecular clouds and 42 smaller clouds. We perform correlations between the IR emission/extinction, and atomic and molecular gas tracers. We compare the atomic gas that surrounds the molecular cloud with the molecular gas in the cloud. Using a dust emission model, we derive the physical properties of dust in and outside the clouds: equilibrium temperature, emissivity and extinction. We also determine the luminosity of the interstellar radiation field intercepted by the cloud, and the total IR luminosity. Statistically, we do not find any significant difference in the dust properties between the atomic and the molecular phases. In particular we do not find evidence for a systematic decrease of the dust temperature in the molecular phase, with respect to the surrounding, presumably atomic gas. This is probably because giant molecular clouds are the sites of star formation, which heat the dust, while the smallest clouds are unresolved. The ratio between the IR luminosity and the cloud mass (LDust/Mgas) does not seem to correlate with Mgas. The highest value of the ratio we derived is 18.1 Lsol/Msol in the 30 Doradus region, which is known to be the most prominent star formation region of the LMC, while the most likely value is 0.5 and is representative of quiescent clouds. We provide a prescription to associate the various stages of star formation with its LDust/Mgas.Comment: Accepted for publication in A

Molecular Clouds as Cosmic Ray Laboratories

We will here discuss how the gamma-ray emission from molecular clouds can be used to probe the cosmic ray flux in distant regions of the Galaxy and to constrain the highly unknown cosmic ray diffusion coefficient. In particular we will discuss the GeV to TeV emission from runaway cosmic rays penetrating molecular clouds close to young and old supernova remnants and in molecular clouds illuminated by the background cosmic ray flux.Comment: to appear on Proceedings of 25th Texas Symposium on Relativistic Astrophysic