25 research outputs found

    Photoemission from the gas phase using soft x-ray fs pulses: An investigation of the space-charge effects

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    An experimental and computational investigation of the space-charge effects occurring in ultrafast photoelectron spectroscopy from the gas phase is presented. The target sample CF3_3I is excited by ultrashort (100 fs) far-ultraviolet radiation pulses produced by a free-electron laser. The modification of the energy distribution of the photoelectrons, i.e. the shift and broadening of the spectral structures, is monitored as a function of the pulse intensity. A novel computational approach is presented in which a survey spectrum acquired at low radiation fluence is used to determine the initial energy distribution of the electrons after the photoemission event. The spectrum modified by the space-charge effects is then reproduced by NN-body calculations that simulate the dynamics of the photoelectrons subject to the mutual Coulomb repulsion and to the attractive force of the positive ions. The employed numerical method allows to reproduce the complete photoelectron spectrum and not just a specific photoemission structure. The simulations also provide information on the time evolution of the space-charge effects on the picosecond scale. Differences with the case of photoemission from solid samples are highlighted and discussed. The presented simulation procedure constitutes an effective tool to predict and account for space-charge effect in time-resolved photoemission experiments with high-intensity pulsed sources.Comment: 18 pages, 4 figures, 1 tabl

    福島県森林集水域における放射性セシウム濃度と外部被ばく線量評価

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    Monitoring of radiocesium activity concentration in stream water, river sediment and riverbank soil, and measurement of air dose rate were carried out in the forest catchments in 2018, and then external exposure doses of workers were measured using the dosimenter (DOSEe nano and D-Shuttle) and GPS. The external exposure doses of workers were calculated with based on the results of measurement of radiation dose rates. The observed ranges of air dose rate were 0.5~2.2 uSv/hr around Maeda river area in Ishikuma (Futaba town) and, 3.7~4.8 uSv/hr around Saruta river in Kajiyadaira and 0.5~2.2 uSv/hr in Sarutahashi (Namie town), respectively. Estimated external exposure doses due to work in 3 hours around Kajiyadaira were 2.4~3.0 Sv/hr (DOSEe nano) and 1.7~2.4 Sv/hr (D-Shuttle). These may be caused by the difference in accumulation time of the dosimeter, as the accumulation time of DOSEe nano and D-Shuttle are 1 minute and 1 hour, respectively. The dose rates calculated from the dosimeter installed on the dashboard of the car for reference were similar to the low values of worker. In this presentation, we report about the evaluation of external external dose and the relationship with the radiocesium activity concentrations around the forest catchments in 2018.第5回福島大学環境放射能研究所成果報告

    HPV-negatives Plattenepithelkarzinom der Zunge bei einer 16-jährigen Patientin

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    Wir berichten über den Fall einer 16-jährigen Patientin mit einem ausgedehnten Plattenepithelkarzinom der Zungenunterseite. Die Patientin gehört anamnestisch keiner Risikogruppe (bezüglich Nikotin- und/oder Alkoholabusus) an, eine Aspestexposition wird verneint und histologisch konnte keine HPV-Assoziation nachgewiesen werden. Plattenepithelkarzinome treten statistisch vornehmlich ab dem 6. Lebensjahrzehnt und gehäuft bei Patienten mit Nikotin- und Alkoholabusus auf. Die Erkrankung ist bei Kindern und Jugendlichen sehr selten. Nur 0,4-5,5% der Fälle treten vor dem 40. Lebensjahr auf. Die schlechte Überlebensprognose bei jungen Patienten ist damit zu erklären, daß diese Differnzialdiagnose bei Kindern oder Jugendlichen nicht bedacht wird und es zu einer verzögerten Diagnosestellung kommt, des Weiteren sind Karzinome der Mundhöhle im jungen Alter meist histologisch gering differenziert und aggressiv wachsend

    Behavior of Radiocaesium in Forest Catchments Contaminated by the Fukushima Dai-ichi Nuclear Power Station Accident

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    A huge amount of radionuclides such as radiocaesium and radiostrontium were dispersed and deposited on the territorial area of Fukushima Prefecture, Japan, after the accident at the TEPCO Fukushima Daiichi Nuclear Power Station (FDNPS) on March 2011. Since Fukushima prefecture is covered by 70% of forest area, it is important to clear the distribution, behavior and runoff process of radiocaesium in this area. In this study, we collected stream water from two type of forest catchments (the difference of air does rate) and river water in mainstream within evacuation zone in vicinity of the FDNPS from December 2017 to January 2019, and assessed the distribution, biogeochemical behavior and fluxes of dissolved radiocaesium in these areas. Activity concentrations of dissolved Cs-137 in stream water collected in Takase River (mainstream: ~1 μSv/h), Saruta River (~4 μSv/h), and Maeda River (~2 μSv/h) ranged from 10.3 to 37.2 mBq/L, 44.3 to 322.9 mBq/L and 8.6 to 29.8 mBq/L, respectively. These results indicate that the activity concentration of dissolved radiocaesium is depended on the air does rate around catchment area in the river. Also, activity concentration of dissolved radiocaesium collected in Takase River and Maeda River related to water temperature. This result suggests that influential source of dissolved radiocaesium in these two rivers are desorption from litter. However, activity concentration of dissolved radiocaesium in Saruta River unrelated to water temperature. The relationship between activity concentration of dissolved radiocaesium and total concentration of sodium and potassium showed positive correlation. From these results, it is inferred that some part of radiocaesium in Saruta River is likely bonded to an exchangeable fraction of particles, which is easy to leach into the water caused by ion exchange.2nd International Conference on Radioanalytical and Nuclear Chemistry(RANC 2019

    Effects of Nicotine Chewing Gum on UPDRS Score and P300 in Early-onset Parkinsonism

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    It has been reported that nicotine shows some beneficial effects on Parkinson's disease. The purpose of the present study is to assess the therapeutic effects of nicotine chewing gum in patients with early-onset parkinsonism (EOP). The subjects were 8 patients with early-onset parkinsonism (male/ female = 4/ 4, mean age; 51.3 years). Four out of 8 patients had a history of smoking (smokers). To estimate the effects of nicotine gum, the scores on the Unified Parkinson's Disease Rating Scale (UPDRS) and auditory event-related potentials (ERPs) were studied before and after taking nicotine gum in the EOP patients. In smokers, UPDRS scores improved by more than 10 % and the P300 latency of auditory ERPs was shortened by more than 30 msec. In contrast, nicotine had no remarkable effects on UPDRS scores or auditory ERPs in non-smokers. We suggest that nicotine chewing gum may be a possible choice for the treatment of patients with EOP, especially when they are smokers

    SIMULATION OF STEEL CORROSION IN CONCRETE BASED ON THE MODEL OF MACRO-CELL CORROSION CIRCUIT

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    [[abstract]]One comprehensive numerical simulation system is proposed for solving the problem of steel corrosion in concrete related to deterioration of reinforced concrete structures under the environment contaminated by chloride ions. Distribution of corrosion amount and corrosion rate along a reinforced bar is calculated based on macro-cell circuit model, which is constituted from micro-cell circuit model. Models are quantified by results of exposure experiments to two environments, one is cyclic wetting and drying in laboratory and the other is splash zone at offshore. The comparisons on time-dependent half-cell potential, corrosion location and corrosion amount indicate the quality coincidence between experimental and analytical results. Examples of calculation on macro-cell corrosion generated between patched area and non-patched area are shown
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