手足としての介助者像とその社会的帰結 : 神経難病療養における障害者と介助者の関係の検討

学位の種別: 課程博士審査委員会委員 : （主査）東京大学准教授 赤川 学, 東京大学教授 松本 三和夫, 東京大学教授 武川 正吾, 東京大学教授 白波瀬 佐和子, 東京大学教授 榊原 哲也University of Tokyo(東京大学

Spacio-temporal distributions of atmospheric nitrous oxide and its isotopocules in the Arctic region

第6回極域科学シンポジウム分野横断セッション：[IA] 急変する北極気候システム及びその全球的な影響の総合的解明―GRENE北極気候変動研究事業研究成果報告2015―11月19日（木）　国立極地研究所１階交流アトリウ

The LTE simulation on decaying arc plasmas in various arc quenching gases in a model circuit breaker

The present report describes numerical thermofluid simulation results of various gas arcs in a nozzle space at atmospheric pressure on the assumption of local thermodynamic equilibrium condition. It is crucial to investigate fundamentals on arc extinction phenomena by numerical simulation approach as well as experimental approach. The SF6, Ar, CO2 and N2 arcs in our experimental setup were treated for the present calculation because we can accurately control the voltage and arc current in our experimtants and we can perform accurate electron density measurements for fundamental investigation and comparison. Two-dimensional temperature distributions in various gas-blast arcs were calculated in a steady state at a direct current of 50 A. Furthermore, transient temperature distributions in these arcs were computed under free recovery condition. Then, we calculated transient responses under free recovery condition by using calculated results in the steady state. The calculated arc voltage in the steady state and the transition of electron density under free recovery condition were compared with those obtained by laser Thomson scattering method in our experiments. © 2015 IEEE

Development of an atmospheric N2O isotopocule model and optimization procedure, and application to source estimation

This paper presents the development of an atmospheric N2O isotopocule model based on a chemistry-coupled atmospheric general circulation model (ACTM). We also describe a simple method to optimize the model and present its use in estimating the isotopic signatures of surface sources at the hemispheric scale. Data obtained from ground-based observations, measurements of firn air, and balloon and aircraft flights were used to optimize the long-term trends, interhemispheric gradients, and photolytic fractionation, respectively, in the model. This optimization successfully reproduced realistic spatial and temporal variations of atmospheric N2O isotopocules throughout the atmosphere from the surface to the stratosphere. The very small gradients associated with vertical profiles through the troposphere and the latitudinal and vertical distributions within each hemisphere were also reasonably simulated. The results of the isotopic characterization of the global total sources were generally consistent with previous one-box model estimates, indicating that the observed atmospheric trend is the dominant factor controlling the source isotopic signature. However, hemispheric estimates were different from those generated by a previous two-box model study, mainly due to the model accounting for the interhemispheric transport and latitudinal and vertical distributions of tropospheric N2O isotopocules. Comparisons of time series of atmospheric N2O isotopocule ratios between our model and observational data from several laboratories revealed the need for a more systematic and elaborate intercalibration of the standard scales used in N2O isotopic measurements in order to capture a more complete and precise picture of the temporal and spatial variations in atmospheric N2O isotopocule ratios. This study highlights the possibility that inverse estimation of surface N2O fluxes, including the isotopic information as additional constraints, could be realized

Evaluation on current interruption ability of CO2 and SF6 using current and voltage application highly controlled by power semiconductors

This paper reports a new simple test technique to evaluate current interruption ability of arc quenching gases. In the test, current and voltage applied to the arc was controlled using a insulated gate bipolar transistor (IGBT). Switching the IGBT enables us to produce free recovery conditions for a fundamental arc decay in nozzles. In addition to this, a voltage was intentionally applied to the free recovery arcs between the electrodes by switching-off IGBT again at the specified delay time td. This applied voltage is called quasi transient recovery voltage (quasi-TRV). We can evaluate successful interruption or interruption failure by measuring the current between the electrodes after quasi-TRV application. We compared the interruption ability of SF6 and CO2 through this developed technique. The experimental results show that a residual arc in SF6 gas flow decays four times more rapidly than that in CO2 gas flow. Influence of observation holes in the nozzles used in the experiments was also investigated, showing less influence of observation on the arc behavior. © 2015 IEEE

Temporal Characteristics of CH4 Vertical Profiles Observed in the West Siberian Lowland Over Surgut From 1993 to 2015 and Novosibirsk From 1997 to 2015

We have carried out monthly flask sampling using aircraft, in the altitude range of 0-7 km, over the boreal wetlands in Surgut (61°N, 73°E; since 1993) and a pine forest near Novosibirsk (55°N, 83°E; since 1997), both located in the West Siberian Lowland (WSL). The temporal variation of methane (CH4) concentrations at all altitudes at both sites exhibited an increasing trend with stagnation during 2000-2006 as observed globally from ground-based networks. In addition to a winter maximum as seen at other remote sites in northern middle to high latitudes, another seasonal maximum was also observed in summer, particularly in the lower altitudes over the WSL, which could be attributed to emissions from the wetlands. Our measurements suggest that the vertical gradient at Surgut has been decreasing; the mean CH4 difference between 5.5 km and 1.0 km changed from 64 ± 5 ppb during 1995-1999 to 37 ± 3 ppb during 2009-2013 (mean ± standard error). No clear decline in the CH4 vertical gradient appeared at Novosibirsk. Simulations using an atmospheric chemistry-transport model captured the observed decrease in the vertical CH4 gradient at Surgut when CH4 emissions from Europe decreased but increased from the regions south of Siberia, for example, East and South Asia. At Novosibirsk, the influence of the European emissions was relatively small. Our results also suggest that the regional emissions around the WSL did not change significantly over the period of our observations

The Orbiting Carbon Observatory (OCO-2) Tracks 2-3 Peta-Gram Increase in Carbon Release to the Atmosphere During the 2014-2016 El Nino

The powerful El Nio event of 2015-2016 - the third most intense since the 1950s - has exerted a large impact on the Earth's natural climate system. The column-averaged CO2 dry-air mole fraction (XCO2) observations from satellites and ground based networks are analyzed together with in situ observations for the period of September 2014 to October 2016. From the differences between satellite (OCO-2) observations and simulations using an atmospheric chemistry-transport model, we estimate that, relative to the mean annual fluxes for 2014, the most recent El Nio has contributed to an excess CO2 emission from the Earth's surface (land+ocean) to the atmosphere in the range of 2.4+/-0.2 PgC (1 Pg = 10(exp 15) g) over the period of July 2015 to June 2016. The excess CO2 flux is resulted primarily from reduction in vegetation uptake due to drought, and to a lesser degree from increased biomass burning. It is about the half of the CO2 flux anomaly (range: 4.4-6.7 PgC) estimated for the 1997/1998 El Nio. The annual total sink is estimated to be 3.9+/-0.2 PgC for the assumed fossil fuel emission of 10.1 PgC. The major uncertainty in attribution arise from error in anthropogenic emission trends, satellite data and atmospheric transport

TransCom N2O model inter-comparison - Part 2:Atmospheric inversion estimates of N2O emissions

This study examines N2O emission estimates from five different atmospheric inversion frameworks based on chemistry transport models (CTMs). The five frameworks differ in the choice of CTM, meteorological data, prior uncertainties and inversion method but use the same prior emissions and observation data set. The posterior modelled atmospheric N2O mole fractions are compared to observations to assess the performance of the inversions and to help diagnose problems in the modelled transport. Additionally, the mean emissions for 2006 to 2008 are compared in terms of the spatial distribution and seasonality. Overall, there is a good agreement among the inversions for the mean global total emission, which ranges from 16.1 to 18.7 TgN yr(-1) and is consistent with previous estimates. Ocean emissions represent between 31 and 38% of the global total compared to widely varying previous estimates of 24 to 38%. Emissions from the northern mid- to high latitudes are likely to be more important, with a consistent shift in emissions from the tropics and subtropics to the mid- to high latitudes in the Northern Hemisphere; the emission ratio for 0-30A degrees N to 30-90A degrees N ranges from 1.5 to 1.9 compared with 2.9 to 3.0 in previous estimates. The largest discrepancies across inversions are seen for the regions of South and East Asia and for tropical and South America owing to the poor observational constraint for these areas and to considerable differences in the modelled transport, especially inter-hemispheric exchange rates and tropical convective mixing. Estimates of the seasonal cycle in N2O emissions are also sensitive to errors in modelled stratosphere-to-troposphere transport in the tropics and southern extratropics. Overall, the results show a convergence in the global and regional emissions compared to previous independent studies

Regional Methane Emission Estimation Based on Observed Atmospheric Concentrations (2002-2012)

Methane (CH4) plays important roles in atmospheric chemistry and short-term forcing of climate. A clear understanding of atmospheric CH4’s budget of emissions and losses is required to aid sustainable management of Earth’s future environment. We used an atmospheric chemistry-transport model (JAMSTEC’s ACTM) for simulating atmospheric CH4. A global inverse modeling system has been developed for estimating CH4 emissions from 53 land regions for 2002-2012 using measurements at 39 sites. An ensemble of 7 inversions is performed by varying a priori emissions. Global net CH4 emissions varied between 505-509 and 524-545 Tg yr-1 during 2002-2006 and 2008-2012, respectively (ranges based on 7 inversion cases), with a step like increase in 2007 in agreement with atmospheric measurements. The inversion system did not account for interannual variations in OH radicals reacting with CH4 in the atmosphere. Our results suggest that the recent update of the EDGAR inventory (version 4.2FT2010) overestimated the global total emissions by at least 25 Tg yr-1 in 2010. The increase in CH4 emission since 2004 originated in the tropical and southern hemisphere regions, coinciding with an increase in non-dairy cattle stocks by ~10 % from 2002 (with 1056 million heads) to 2012, leading to ~10 Tg yr-1 increase in emissions from enteric fermentation. All 7 ensemble cases robustly estimated the interannual variations in emissions, but poorly constrained the seasonal cycle amplitude or phase consistently for all regions due to the sparse observational network. Forward simulation results using both a priori and a posteriori emissions are compared with independent aircraft measurements for validation. Based on the results of the comparison, we reject the upper limit (545 Tg yr-1) of global total emissions as 14 Tg yr-1 too high during 2008-2012, which allows us to further conclude that the increase in CH4 emissions over the East Asia (mainly China) region was 7-8 Tg yr-1 between the 2002-2006 and 2008-2012 periods, contrary to 1-17 Tg yr-1 in the a priori emissions

Temporal Variations of the Mole Fraction, Carbon, and Hydrogen Isotope Ratios of Atmospheric Methane in the Hudson Bay Lowlands, Canada

We have conducted simultaneous measurements of the mole fraction and carbon and hydrogen isotope ratios (δ13C and δD) of atmospheric methane (CH4) at Churchill (58°44′N, 93°49′W) in the northern part of the Hudson Bay Lowlands (HBL), Canada, since 2007. Compared with the measurements at an Arctic baseline monitoring station, Ny‐Alesund, Svalbard (78°55′N, 11°56′E), CH4 mole fraction is generally higher and δ13C and δD are lower at Churchill due to regional biogenic CH4 emissions. Clear seasonal cycles in the CH4 mole fraction, δ13C, and δD are observable at Churchill, and their seasonal phases in summer are earlier by approximately 2 weeks than those at Ny‐Alesund. Using the one‐box model analysis, the phase difference is ascribed to the different seasonal influence of CH4 emissions from boreal wetlands on the two sites. Short‐term CH4 variations are also observed at Churchill throughout the year. The analysis of the observed isotopic signatures of atmospheric CH4 confirmed that the short‐term CH4 variations are mainly produced by biogenic CH4 released from the HBL wetlands in summer and by fossil fuel CH4 transported over the Arctic in winter. Forward simulations of an atmospheric chemistry‐transport model, with wetland CH4 fluxes prescribed by a process‐based model, show unrealistically high CH4 mole fractions at Churchill in summer, suggesting that CH4 emissions assigned to the HBL wetlands are overestimated. Our best estimate of the HBL CH4 emissions is 2.7 ± 0.3 Tg CH4 yr?1 as an average of 2007-2013, consistent with recent estimations by inverse modeling studies