宇宙線μ中間子による屋内被曝のコンピュータ数値実験を非散乱・非カスケード近似の枠の中で実行した。モデルとして考える建物は矩形をなし, 標準コンクリートでできているとした。各建物は積層構造を持ち, 中2階などはないものとした。また壁の存在は考慮しなかった。いろいろな26階建てビルの内部の照射線量率分布を各パラメータ群ごとに等高線図によって示した。いずれも基本的にはアーチ状の分布パターンを示した。その解析結果によれば, 照射線量率は床板の厚みによって最も大きな影響を受ける。天井の高さは背の低い建物に対してはあまり影響がなさそうである。また中程度の大きさの建物内部の照射線量率の最小値/最大値の比は0.7を超えると推定された。

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Interactions between cosmic rays and atmospheric components produce various nuclear fragments. Cosmogenic ⁷Be distributes uniformly in the atmosphere which covers all over the earth. Thus, the vertical and horizontal transport of ⁷Be in the stratosphere as well as troposphere will work as an effective tracer with half life of 53.3 days. Many studies have been conducted on ⁷Be atmospheric concentration and deposition onto the ground. Generally, the atmospheric ⁷Be concentration and the ⁷Be deposition show seasonal and yearly variations which are controlled by solar activity, cosmic ray intensity, atmospheric circulation and other mechanisms such as “washout” and “rainout”. This paper presents atmospheric ⁷Be concentration and ⁷Be deposition data obtained by the authors as well as other investigators. The variations of atmospheric ⁷Be concentration and ⁷Be deposition and their influential factors are also reviewed.

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The author published in his present investigation of the heredity of the human blood group types, Part II, his own theory. The hypothesis he then propounded required as a matter of course a supplementary hypothesis, which, however, was left unstated; hence it may be here supplemented.
The supplementary hypothesis in question is the theory of the “Lethal Factor” put forward by Dyke & Budge. The gamete AB is weak in vitality, and, moreover, some phenomenon yet unexplained today takes place in the perion in which a blood type is formed. From these facts it is assumed that the gamete AB perishes in one generation. This assumption also corresponds to the instances reported by and Ito.

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The collective dose due to the background radiation outdoors in Japan was analyzed, and the influence of the time trend of the population movement on the per capita dose was estimated. Only the external dose was considered. It was previously shown that the per capita dose calculated for each year between 1952 and 1980 by the use of the surveyed background levels along with the registered population data has been decreasing continuously. In this work, the latest data in 1981 was added, and male and female statistics were pro-cessed separately. The result showed that the male values of the per capita dose have been always lower than the female values, if the deficit is small. It was also shown pre-viously that the prevailing population movement from countryside toward urban areas (often plains of volcanic ash) would be the cause which have changed the per capita dose, i.e. population-weighted mean dose of the whole country. In this work, it was anticipated that the gross population movement from the South-West toward the North-East Japan would be another cause of the decrease.

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The long term variation of the mean dose due to natural radiation in Japan received by an individual person was investigated. The mean exposure rate in each prefecture obtained by in-situ measurements was adopted as a basis of the radiation level. Population data were taken from both the resident registration and the census taking into account the essential difference of their meanings. It was revealed that the per capita dose due to outdoor natural radiaiton in Japan has been decreasing in the last approximate 30 yr. It will be due to the population movement from countrysides towards urban areas. That is because countrysides generally consist of stable mountainlands where granitic rocks distribute though urban areas generally consist of alluvial plains where volcanic ash or humus dominates. Although the contribution of low radiation level (below 9.0 μR/h) areas to the nation-wide collective dose still remains under 50%, its relative importance has certainly been increasing in the last three decades. It is expected that human population will be the dominating factor which eventually controls the mean dose due to natural radiation in Japan.

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Electronic Personal Dosemeter (EPD) was examined for effectiveness in cosmic radiation dosimetry at aircraft altitude through the measurements in a Japan-US round trip. The EPD value (H_epd) of individual dose equivalent, penetrating, H_p (10), was considered to be almost equal the deep absorbed dose attributed to electrons at the aircraft altitude. By assuming the fractions and the effective quality factors for other components (muons, protons, and neutrons) based on model-calculation data, an empirical equation to estimate a conservative deep dose-equivalent at 5 cm-tissue depth, H (50), was given as H (50) =3.1×H_epdEstimated H (50) values in the international flights were 4.9μSvh^-1from Tokyo to New York and 3.6μSvh^-1from Los Angeles to Tokyo. These values agreed well with the predicted values presented by NCRP.

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The first InterComparison for Cosmic-ray with Heavy Ion Beams At NIRS (ICCHIBAN) project is an ongoing, international collaboration organized at the National Institute of Radiological Sciences (NIRS), Japan, for the purpose of characterizing and comparing at a controlled, ground-based heavy ion facility the radiation response of instruments used aboard piloted spacecraft for crew and area dosimetry. We present preliminary results from the first set of ICCHIBAN exposures made at HIMAC heavy ion accelerator in February 2002. The initial series of exposures (1^st ICCHIBAN run) was designed to establish the response of active detectors to two well-characterized heavy ion beams; 400 MeV/nucleon ¹²C and 400 MeV/nucleon ⁵⁶Fe. These beams are representative in charge and energy of two of the most significant heavy ion components present in the galactic cosmic radiation spectrum. The properties of the incident beam, including intensity, profile, charge and total energy, were characterized using several different detector systems, including silicon detectors, CR-39 plastic nuclear track detectors and plastic scintillation counters. Once the response of each detector to heavy ion beams of known composition has been measured, results from on-orbit measurements made by the different instruments can be more meaningfully compared. We conclude by discussing plans for future ICCHIBAN runs, including next 2^nd ICCHIBAN run for passive detectors in early summer 2002.

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Type 2 diabetes mellitus (T2DM) associated with metabolic syndrome (MetS) represents a high risk of cardiovascular disease. We compared the effect of early intervention with pioglitazone versus voglibose on physical and metabolic profiles and serum adiponectin level in patients with T2DM associated with MetS. Sixty patients who were diagnosed for the first time as T2DM associated with MetS were analyzed for insulin sensitivity, lipid profile, serum adiponectin and systemic inflammation. Those patients were randomly assigned to oral pioglitazone group (n = 30) or voglibose group (n = 30) in addition to conventional diet and exercise training. Body mass index and waist circumference did not change in the pioglitazone group, whereas these physical parameters significantly decreased in the voglibose group during a 6-month follow-up period. However, glycosylated hemoglobin, fasting plasma glucose, and HOMA-IR more significantly decreased in the pioglitazone group. The level of serum adiponectin especially high-molecular weight adiponectin markedly increased in the pioglitazone group. Moreover, high sensitive CRP significantly decreased only in the pioglitazone group. These results suggest that voglibose is superior in improving obesity, while pioglitazone is superior in ameliorating insulin sensitivity and increasing serum adiponectin in patients with an early stage of T2DM associated with MetS.

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宇宙線μ中間子による屋内被曝のコンピュータ数値実験を始めるにあたり, いろいろな物理パラメータの値を決めた。既知の情報を集約するとともに未知のものを新たに計算で求めた。実際的なモデル作りをするうえで立てた仮定や近似もここに記述した。標準コンクリートおよび空気に対するμ中間子の阻止能と飛程は数百GeVまでのエネルギーについて計算された。その結果と既製の数表との比較は低エネルギー部分でのみ可能であるが, そこではよい一致をみせた。宇宙線μ中間子が建物内部で受ける散乱効果はごく簡単なモデル計算によって数値的に調べられたが, きわめて小さい変動を問題にするのでなければその全体としての影響は無視し得るものであることが分かった。また鉄筋コンクリートに含まれる鉄分やコンクリートの密度といった要因も大した影響のないものであることが分かった。

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A simplified system for measuring time-resolved photoluminescence (PL) induced by UV laser pulses (λ= 337nm) is designed by a combination of a commercial PL reader and a digital oscilloscope. Using this system, PL emissions after pulsed UV excitation from a chip of sapphire (Al₂O₃) are successfully measured with intervals of 10ns. It is thus expected that this system will be conveniently used for searching new PL materials that would be more suitable for space radiation dosimetry.

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We observed absorbed dose rate in air at a uranium ore outcrop which is known as one of the high natural radiation spot of the Tono area in central Japan. This outcrop was mainly Toki granite and weathered soil. The absorbed dose rate in air measured on the rock and surface soil using a pocket survey meter ranged from 572 to 9684 nGy h^-1, and significantly high values were observed at a small rock body and the bottom of a trench. The uranium concentration of the soil in the trench was 1220 ppm which is a significantly high value. The measured absorbed dose rates in air were reasonably high compared with the general environment.

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Extensive field survey on natural radiation was conducted from 1967 to 1991 over Japan Islands. The average level of the islands was found to be 79.7 nGy/h. In general, Southwest Japan has higher level compared with the Northeast one. From the data obtained at 1304 sites of the survey, a contour map of natural radiation level in the islands was made by simple interpolations, and a geological interpretation on the distribution of the level was done by comparing the contour map with geological information. The islands were divided into four areas according to whether the level is higher or lower than the average level. The boundaries between these areas were found almost exactly coincide with major geo-tectonic lines. This feature suggests that natural radiation level is controlled mainly by distribution of granitic and volcanic rocks.

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The biggest concern about the health risk to astronauts is how large the stochastic effects (cancers and hereditary effects) of space radiation could be. The practical goal is to determine the "effective dose" precisely, which is difficult for each crew because of the complex transport processes of energetic secondary particles. The author and his colleagues thus attempted to measure an effective dose in space using a life-size human phantom torso in the STS-91 Shuttle-Mir mission, which flew at nearly the same orbit as that of the International Space Station (ISS). The effective dose for about 10-days flight was 4.1 mSv, which is about 90% of the dose equivalent (H) at the skin; the lowest H values were seen in deep, radiation-sensitive organs/tissues such as the bone marrow and colon. Succeeding measurements and model calculations show that the organ dose equivalents and effective dose in the low Earth orbit mission are highly consistent, despite the different dosimetry methodologies used to determine them.

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症例は44歳男性．10年来口渇，多飲，多尿を認めるも放置していた．受診の約1年前より両下腿の浮腫を認めるようになり近医を受診し，2型糖尿病と診断され内服治療となっていた．平成15年2月5日頃より左大腿部痛を認め近医を経て2月18日入院した．CK高値（932 U/l）炎症反応高値（CRP 4.31 mg/dl）を認めたため，左大腿筋炎を疑われ3月3日筋生検を施行した．筋繊維の壊死，変性，萎縮，線維化を認め臨床経過とあわせ糖尿病性筋梗塞（diabetic muscle infarction）と診断した．安静，血糖コントロール，理学療法にて症状の改善を認めた．

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Natural background radiation in Japan was analyzed based on surveyed data which were rearranged from macroscopic points of view. The background levels were classified into seventeen groups from which a contour map was made by simple interpolations. The general pattern obtained showed that high levels are prominent in Hida Mountains-Wakasa Bay area and Joetsu-northern Kanto provinces, and low levels are prominent in Hokkaido and northern Tohoku districts along with Kanto Plain. The whole area was further divided into two classes according to whether the level is higher than the country-wide mean level. A boundary between the two classes seen in Chubu District was found almost exactly coincides with Itoigawa-Shizuoka Tectonic Line. Kanto Mountainland was found to have higher levels than its neighborhood, which supports the current idea that old geology of granitic rocks gives high level radiation. A good correspondence could be seen between the radiation contours and every tectonic line proposed as the eastern border of Fossa Magna which is important in the tectonics of Japan Islands. It was then anticipated that informations of the natural radiation will give valuable side evidences to infer the geologic history of Japan Islands.

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The atmospheric concentration and deposition flux of cosmogenic ⁷Be were observed at Toki city, Gifu Prefecture, located in the central region of Japan, from September 2013 to March 2017, to understand the regional characteristics of the atmospheric environment. Atmospheric ⁷Be concentration ranged from 1.92 to 6.97 mBq m^-3 and high concentrations were observed in spring and fall. ⁷Be deposition ranged from 35.2 to 281.6 Bq m^-2 and it had a single peak in summer depending on monthly precipitation. These results are comparable to the previously reported values. Total deposition velocity of ⁷Be ranged from 0.25 to 4.92 cm sec^-1 with a mean value of 1.48 ±0.88 cm sec-1, and showed a seasonal variation pattern with a single large peak in summer which is similar to deposition pattern. These results suggest that precipitation is an important control factor of total deposition velocity.

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Space radiation exposures are distinct from those in charged particle radiotherapy in that they are typically low dose, low dose rate and mixed field. It is not feasible to exactly replicate these conditions in ground-based facilities, but carefully designed experiments at HIMAC have provided insight into the biological effects of space radiation.

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