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論文

Catalog of gamma-ray glows during four winter seasons in Japan

和田 有希*; 松本 崇弘*; 榎戸 輝揚*; 中澤 知洋*; 湯浅 孝行*; 古田 禄大*; 米徳 大輔*; 澤野 達哉*; 岡田 豪*; 南戸 秀仁*; et al.

Physical Review Research (Internet), 3(4), p.043117_1 - 043117_31, 2021/12

In 2015 the Gamma-Ray Observation of Winter Thunderstorms (GROWTH) collaboration launched a mapping observation campaign for high-energy atmospheric phenomena related to thunderstorms and lightning discharges. This campaign has developed a detection network of gamma rays with up to 10 radiation monitors installed in Kanazawa and Komatsu cities, Ishikawa Prefecture, Japan, where low-charge-center winter thunderstorms frequently occur. During four winter seasons from October 2016 to April 2020, in total 70 gamma-ray glows, minute-lasting bursts of gamma rays originating from thunderclouds, were detected. Their average duration is 58.9 sec. Among the detected events, 77% were observed in nighttime. The gamma-ray glows can be classified into temporally-symmetric, temporally-asymmetric, and lightning-terminated types based on their count-rate histories. An averaged energy spectrum of the gamma-ray glows is well fitted with a power-law function with an exponential cutoff, whose photon index, cutoff energy, and flux are 0.613 $$pm$$ 0.009, 4.68 $$pm$$ 0.04 MeV, and (1.013 $$pm$$ 0.003) $$times$$ 10$$^{-5}$$ erg cm$$^{-2}$$s$$^{-1}$$ (0.2-20.0 MeV), respectively. The present paper provides the first catalog of gamma-ray glows and their statistical analysis detected during winter thunderstorms in the Kanazawa and Komatsu areas.

論文

Multiple gamma-ray glows and a downward TGF observed from nearby thunderclouds

久富 章平*; 中澤 知洋*; 和田 有希*; 辻 結菜*; 榎戸 輝揚*; 篠田 太郎*; 森本 健志*; 中村 佳敬*; 湯浅 孝行*; 土屋 晴文

Journal of Geophysical Research; Atmospheres, 126(18), p.e2021JD034543_1 - e2021JD034543_12, 2021/09

 被引用回数:13 パーセンタイル:83.81(Meteorology & Atmospheric Sciences)

Around 17:00 on January 12, 2020 (UTC), radiation detectors installed at two locations with a 1.35 km separation in Kanazawa City, Japan, captured a total of four gamma-ray enhancements. The first pair was simultaneously observed at the two locations at 17:03 and were abruptly terminated by a lightning discharge. The remaining two enhancements were also nearly simultaneously observed $$sim$$3 min later, and one of them was also terminated by another lightning discharge. At the last termination, a downward terrestrial gamma-ray flash and a negative energetic in-cloud pulse were observed. Both pairs were associated with thundercloud cells. In the first pair, simultaneous detection in two locations 1.35 km apart suggests either a gamma-ray glow emerged in-between and time variability of its intensity were directly observed or there were two (or more) gamma-ray glows in the cell which reached the two detectors coincidentally. In the latter pair, the peak time in the downwind detector was $$sim$$40 s later than that of the upwind detector. If the irradiation region moved with the cell, it would have taken $$sim$$110 s. The discrepancy suggests either the glow moved 2.5 times faster than the cell or there were two (or more) glows in the cell. Also, the fact that the thunderstorm cell hosting the latter glows experienced the lightning discharge $$sim$$3 min before suggests that the strong electric field in the cell can develop within a few minutes.

論文

Thundercloud project; Exploring high-energy phenomena in thundercloud and lightning

湯浅 孝行*; 和田 有希*; 榎戸 輝揚*; 古田 禄大; 土屋 晴文; 久富 章平*; 辻 結菜*; 奥田 和史*; 松元 崇弘*; 中澤 知洋*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2020(10), p.103H01_1 - 103H01_27, 2020/10

 被引用回数:13 パーセンタイル:76.43(Physics, Multidisciplinary)

We designed, developed, and deployed a distributed sensor network aiming at observing high-energy ionizing radiation, primarily gamma rays, from winter thunderclouds and lightning in coastal areas of Japan. Starting in 2015, we have installed, in total, more than 15 units of ground-based detector system in Ishikawa Prefecture and Niigata Prefecture, and accumulated 551 days of observation time in four winter seasons from late 2015 to early 2019. In this period, our system recorded 51 gamma-ray radiation events from thundercloud and lightning. Highlights of science results obtained from this unprecedented amount of data include the discovery of photonuclear reaction in lightning which produces neutrons and positrons along with gamma rays, and deeper insights into the life cycle of a particle-acceleration and gamma-ray-emitting region in a thunder-cloud. The present paper reviews objective, methodology, and results of our experiment, with a stress on its instrumentation.

論文

Seasonal variation in serum lipid levels in Japanese workers

亀崎 文彦; 園田 信成*; 友常 祐介; 湯中 弘美; 尾辻 豊*

Journal of Atherosclerosis and Thrombosis, 17(6), p.638 - 643, 2010/07

 被引用回数:22 パーセンタイル:48.34(Peripheral Vascular Disease)

Seasonal variation in serum lipid levels in Japanese population remains unclear. The aim of this study was to determine whether the variation in lipid levels exists in Japanese workers. We investigated a total of 1,331 employees in our institution (1,192 men, 44$$pm$$10 years; 139 women, 38$$pm$$11 years) who underwent health checkups in both June (summer) and December (winter), 2008. Serum levels of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol, and triglyceride were significantly higher in winter than in summer (129.1$$pm$$31.2 mg/dL versus 125.2$$pm$$30.2 mg/dL, $$p$$ $$<$$ 0.0001; 65.9$$pm$$16.8 mg/dL versus 63.5$$pm$$16.1 mg/dL, $$p$$ $$<$$0.0001; 110.4$$pm$$67.5 mg/dL versus 107.5$$pm$$70.4 mg/dL, $$p$$ $$<$$ 0.05; respectively), although the ratio of LDL to HDL cholesterol was comparable (2.11$$pm$$0.81 in summer versus 2.12$$pm$$0.81 in winter). Frequency of study subjects diagnosed hypercholesterolemia defined as LDL cholesterol $$geq$$140 mg/dL was significantly higher in winter than in summer (34.5% versus 30.9%, $$p$$ $$<$$ 0.0001). In Japanese workers, we demonstrated that there is seasonal variation in serum lipid levels and prevalence of hypercholesterolemia. This result indicates that we have to give careful consideration to the season of blood sampling in clinical diagnosis and management decisions of hypercholesterolemia.

論文

Seasonal variation in metabolic syndrome prevalence

亀崎 文彦; 園田 信成*; 友常 祐介; 湯中 弘美; 尾辻 豊*

Hypertension Research, 33(6), p.568 - 572, 2010/06

 被引用回数:44 パーセンタイル:72.96(Peripheral Vascular Disease)

Accumulating evidences have demonstrated that seasonal variations exist in metabolic syndrome parameters. The aim of this study was to examine the hypothesis that there is seasonal variation in metabolic syndrome prevalence in Japanese subjects. We investigated a total of 1,202 male workers in our institution (44 $$pm$$ 10 years), who underwent health checkups in both June (summer) and December (winter), 2008. In this study, metabolic syndrome was defined according to the criteria proposed by National Cholesterol Education Program (NCEP), International Diabetes Federation (IDF), and Japanese Society of Internal Medicine (JSIM). Serum levels of high-density lipoprotein-cholesterol and fasting glucose, and blood pressure (BP) were significantly higher in winter than in summer, whereas waist circumference and serum levels of triglyceride were little changed. Prevalence of NCEP-, IDF-, and JSIM- metabolic syndrome in this study was 3.8, 15.1 and 12.4% in winter, 3.2, 10.7 and 8.4% in summer, respectively. Out of the metabolic syndrome components, elevated BP component was mainly connected with the seasonal variation of metabolic syndrome prevalence. The present study demonstrated the seasonal variation in metabolic syndrome prevalence in Japanese male workers. This result indicates that season of health checkups may affect a clinical diagnosis and management of metabolic syndrome.

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