Abstract
In the present study, variations in ambient gamma dose rate associated with snow cover were examined in a radioactive-contaminated site in Fukushima Prefecture, Japan. The ambient gamma dose ...rates decreased with increasing snow depth. The reduction trends were different between fresh snow (0.1–0.2 g/cm3) and granular snow (0.3–0.4 g/cm3) depending on snow density. Snow cover water content (snow water equivalent) calculated from snow depth and density was a key parameter governing the reduction in the ambient gamma dose rate. The ambient gamma dose rates reduced to 0.6 and 0.5 at 4 g/cm2 and 8 g/cm2 of snow water equivalent, respectively. Based on gamma-ray flux density distributions, the ambient gamma dose rates from the primary gamma rays decreased more compared to those from scattered gamma rays due to snow cover.
The contributions of radon and thoron from building materials to total radon (thoron) entry rates in dwellings range from almost zero to several percent. It is necessary to measure radon and thoron ...exhalation rates, among other things, to assess the radiological hazard to human health in a living environment. Brick and granite specimens were used to study the changes of these rates as a function of the relative and absolute humidities. Measurement results showed that radon and thoron exhalation rates change to humidity with the same trends as well as effective dose could be changed by the factor of 2 due to this.
•Humidity has significant effect on radon and thoron exhalation rates.•The exhalation rate tendency was the same for samples with different porosity and density.•Humidity effect should be considered for calculation of the equivalent dose from radon and thoron.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We present component-separated maps of the primary cosmic microwave background/kinematic Sunyaev–Zel’dovich (SZ) amplitude and the thermal SZ Compton-y parameter, created using data from the South ...Pole Telescope (SPT) and the Planck satellite. These maps, which cover the ∼2500 deg2 of the southern sky imaged by the SPT-SZ survey, represent a significant improvement over previous such products available in this region by virtue of their higher angular resolution (1.′25 for our highest-resolution Compton-y maps) and lower noise at small angular scales. In this work we detail the construction of these maps using linear combination techniques, including our method for limiting the correlation of our lowest-noise Compton-y map products with the cosmic infrared background. We perform a range of validation tests on these data products to test our sky modeling and combination algorithms, and we find good performance in all of these tests. Recognizing the potential utility of these data products for a wide range of astrophysical and cosmological analyses, including studies of the gas properties of galaxies, groups, and clusters, we make these products publicly available at http://pole.uchicago.edu/public/data/sptsz_ymap and on the NASA/LAMBDA website.
Motivated by the results of recent transport and optical conductivity studies, we propose a semi-infinite two-dimensional lattice model for interacting massive Dirac electrons in the pressurized ...organic conductor α−(BEDT−TTF)2I3, and address the problem of domain wall conductivity in a charge-ordered insulating phase under realistic experimental conditions. Using the extended Hubbard model at a mean field level, we present results of extensive numerical studies around the critical region of the model, reporting on the resistivity and optical conductivity calculated by means of the Nakano-Kubo formula. We find that the activation gap extracted from the resistivity data can be much smaller than the optical gap in the critical region, which is induced by metallic conduction along a one-dimensional domain wall emerging at the border of two charge-ordered ferroelectric regions with opposite polarizations. The data are consistent with the observed transport gap in real α−(BEDT−TTF)2I3 samples that is reduced remarkably faster than the optical gap upon suppressing charge order with pressure. Our optical conductivity also reveals an additional shoulderlike structure at low energy inside the gap, which is argued to be directly relevant to the metallic bound states residing on the domain wall.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
The present study focuses on internal exposure caused by the inhalation of radon and thoron progenies because the internal exposures have not yet been clarified. For their dose assessment, radon, ...thoron and thoron progeny concentrations were measured by passive monitors over a long period (for 6 months). Consequently, radon, thoron and equilibrium equivalent thoron concentrations were given as 124 ± 78, 1247 ± 1189 and 7.8 ± 9.1 Bq m(-3), respectively. Annual effective doses are estimated to be 3.1 ± 2.0 mSv for radon and 2.2 ± 2.5 mSv for thoron. Total dose are estimated to be 5.3 ± 3.5 mSv a(-1). The present study has revealed that the radon dose was comparable with the thoron dose, and the total dose was ∼2 times higher than the worldwide average.
Bacterial production of humic-like fluorescent dissolved organic matter (FDOM sub(H)) was examined in a 90 d culture experiment using a bacterial assemblage collected from coastal water with ...artificial seawater amended by glucose. A rapid decrease in dissolved organic carbon concentration was noticed during Days 1 to 5, and this coincided with an increase in bacterial numbers. The increase in FDOM sub(H), which was determined by Excitation-Emission Matrix Spectroscopy (EEMS), was observed by Day 20, showing the production of FDOM sub(H) by bacteria. This increase lagged behind the increase in bacterial numbers, suggesting that the production of FDOM sub(H) was accompanied by an alteration of bacterial biomolecules. After Day 30, the fluorescence intensity showed no significant decrease, and 63% of the maximum intensity on Day 20 remained at the end of the experiment. This high remaining percentage likely reflects the recalcitrant properties of bacteria-derived FDOM sub(H) (BAC-FDOM sub(H)). High-performance size-exclusion chromatography with fluorescence detection (Excitation/Emission = 335/410 nm) revealed that most of BAC-FDOM sub(H) is composed of 3 molecular weight (MW) groups having similar fluorescent properties. The MWs of these were all <1.8 kDa relative to standards with known MW. A photodegradation experiment of BAC-FDOM sub(H) demonstrated that the photodegradability of fluorophores varied among the MW groups. Measurements of the MW composition of coastal seawater showed that a recalcitrant fraction of BAC-FDOM sub(H) resistant to solar irradiance constituted a part of FDOM sub(H) in ambient seawater.
Motivated by the results of recent thermoelectric effect studies, we show the effects of Coulomb interactions on the Seebeck coefficient based on an extended Hubbard model that describes the ...electronic states of a slightly doped organic Dirac electron system, α−(BEDT-TTF)2I3. Our results indicate that the Hartree terms of the Coulomb interactions enhance the electron-hole asymmetry of the energy band structure and change the energy dependence of the relaxation time from impurity scattering, which reflects the shape of the density of states. Thus, the Seebeck coefficient exhibits a nonmonotonic T dependence which qualitatively agrees with the experimental results. Furthermore, we also show that the signs of the Seebeck coefficient and the Hall coefficient calculated by linear response theory do not necessarily correspond to the sign of the chemical potential using a modified Weyl model with electron-hole asymmetry. These results point out that changing the electron-hole asymmetry by strong Coulomb interaction has the potential to control the sign and value of the Seebeck coefficient in the Dirac electron systems.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
Abstract The systemic injection of human mesenchymal stem cells (hMSCs) prepared from adult bone marrow has therapeutic benefits after cerebral artery occlusion in rats, and may have multiple ...therapeutic effects at various sites and times within the lesion as the cells respond to a particular pathological microenvironment. However, the comparative therapeutic benefits of multiple injections of hMSCs at different time points after cerebral artery occlusion in rats remain unclear. In this study, we induced middle cerebral artery occlusion (MCAO) in rats using intra-luminal vascular occlusion, and infused hMSCs intravenously at a single 6 h time point (low and high cell doses) and various multiple time points after MCAO. From MRI analyses lesion volume was reduced in all hMSC cell injection groups as compared to serum alone injections. However, the greatest therapeutic benefit was achieved following a single high cell dose injection at 6 h post-MCAO, rather than multiple lower cell infusions over multiple time points. Three-dimensional analysis of capillary vessels in the lesion indicated that the capillary volume was equally increased in all of the cell-injected groups. Thus, differences in functional outcome in the hMSC transplantation subgroups are not likely the result of differences in angiogenesis, but rather from differences in neuroprotective effects.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We present three maps of the millimeter-wave sky created by combining data from the South Pole Telescope (SPT) and the Planck satellite. We use data from the SPT-SZ survey, a survey of 2540 deg2 of ...the the sky with arcminute resolution in three bands centered at 95, 150, and 220 GHz, and the full-mission Planck temperature data in the 100, 143, and 217 GHz bands. A linear combination of the SPT-SZ and Planck data is computed in spherical harmonic space, with weights derived from the noise of both instruments. This weighting scheme results in Planck data providing most of the large-angular-scale information in the combined maps, with the smaller-scale information coming from SPT-SZ data. A number of tests have been done on the maps. We find their angular power spectra to agree very well with theoretically predicted spectra and previously published results.
The vertical change in the composition of marine humic-like fluorescent dissolved organic matter (FDOM
M) and its controlling factors were examined in the subtropical western North Pacific. ...Fluorescence intensity and molecular weight distribution were measured on the hydrophobic fraction of FDOM
M (O-FDOM
M) fractionated with ODS solid phase extraction. Although the same vertical trends with low fluorescence intensity in surface waters and high in deep waters were observed both for bulk FDOM
M and O-FDOM
M, the contribution of O-FDOM
M to bulk FDOM
M decreased with depth. A sunlight irradiation experiment of deep seawater revealed that the fluorescence intensity of O-FDOM
M as well as bulk FDOM
M tended to decrease, whereas the contribution of O-FDOM
M to FDOM
M increased from 42% to 62% throughout the irradiation experiment. This suggests that the hydrophobic fraction is more refractory to photoirradiation than a hydrophilic one and that the difference of photo-lability results in the vertical change of the contribution of O-FDOM
M to FDOM
M. Molecular weight (MW) distributions of O-FDOM
M were measured by high-performance size exclusion chromatography. O-FDOM
M was composed of three MW fractions throughout the samples examined and the compositional change was noted with an increase in the high MW fraction with depth. The photoirradiation experiment of deep seawater sample clearly showed that a high MW fraction was more susceptible than a low MW fraction of O-FDOM
M. The present study strongly suggests that FDOM
M is composed of some fractions with different photoreactivity, and that photoirradiation is the main factor controlling the compositional change in FDOM
M with depth. The fate of each fraction of FDOM
M after photoirradiation is presumably one of the key processes in the biogeochemical cycle of marine DOM.
►Hydrophobic FDOM
M consisted of three molecular weight fractions. ►The composition of FDOM
M differed between surface and mesopelagic waters. ►Sunlight irradiation altered the composition of FDOM
M. ►FDOM
M consisted of different photoreactive components.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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