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1.
During the 29th Soviet Antarctic Expedition in Novolazarevskaya from March 1984 to March 1985, the protein and energy metabolisms were studied in six expeditioners from the German Democratic Republic. The investigations were carried out at the beginning of the expedition (May), during the polar night (July) and during the polar day (December). The effect of a special stress situation (sledge trek in April 1984) was investigated in one subject. The stable nitrogen isotope 15N was used to study the protein metabolism. The assessment of the energy metabolism was based on the oxygen consumption, which was determined by means of a spirograph. In addition, the vital capacity, the breath minute volume, the blood pressure, etc. were measured. The following results were obtained: During the polar night, the utilisation of the dietary proteins and the whole body protein synthesis calculated by means of the 15N excretion of the total nitrogen in urine were greater (73.6±0.9 % and 3.48±0.17 g protein d?1 kg?1, n=3) than the respective values during the polar day (69.7±1.2, p<0.05, n=3 and 3.05±0.07, p<0.05, n=3) and at the beginning of the expedition (69.6±1.4, p<0.02, n=5 and 2.81±0.09, p<0.01, n=5). The lowest values (58.0 % and 2.43 g protein d?1 kg?1) were obtained in the subject after the trek. The resting metabolic rate (in kJ d?1 m?2) was decreased during the polar night (45.6±5.0, n=4) in comparison with the polar day (61.5±11.3, n=3) and the beginning of the expedition (52.3±9.6, n=4) with p<0.01 in both cases.  相似文献   

2.
The rate of neutrino-electron elastic scattering interactions from 862 keV (7)Be solar neutrinos in Borexino is determined to be 46.0±1.5(stat)(-1.6)(+1.5)(syst)?counts/(day·100 ton). This corresponds to a ν(e)-equivalent (7)Be solar neutrino flux of (3.10±0.15)×10(9) cm(-2)?s(-1) and, under the assumption of ν(e) transition to other active neutrino flavours, yields an electron neutrino survival probability of 0.51±0.07 at 862 keV. The no flavor change hypothesis is ruled out at 5.0?σ. A global solar neutrino analysis with free fluxes determines Φ(pp)=6.06(-0.06)(+0.02)×10(10) cm(-2)?s(-1) and Φ(CNO)<1.3×10(9) cm(-2)?s(-1) (95% C.L.). These results significantly improve the precision with which the Mikheyev-Smirnov-Wolfenstein large mixing angle neutrino oscillation model is experimentally tested at low energy.  相似文献   

3.
Stable sulphur isotope fractionation was investigated during reduction of thiosulphate and elemental sulphur at 28°C by growing batch cultures of the sulphur- and thiosulphate-reducing bacteria Dethiosulfovibrio marinus (type strain DSM 12537) and Dethiosulfovibrio russensis (type strain DSM 12538), using citrate as carbon and energy source. The cell-specific thiosulphate reduction rate in the growth phase was 7.4±3.9?fmol?cell(-1)?d(-1). The hydrogen sulphide produced was enriched in (32)S by 10.3±1?‰ compared with total thiosulphate sulphur, close to previous experimental results observed for other sulphate- and non-sulphate-reducing bacteria. Elemental sulphur reduction yields sulphur isotope enrichment factors between-1.3 and-5.2?‰ for D. russensis and-1.7 and-5.1?‰ for D. marinus. The smaller fractionation effects are observed in the exponential growth phase (cellular rates between 5 and 70?fmol?S°?cell(-1)?d(-1)) and enhanced discrimination under conditions of citrate depletion and cell lysis (cellular rates between 0.3 and 3?fmol?S°?cell(-1)?d(-1)).  相似文献   

4.
Highly correlated calculations at the multi-reference configuration interaction levels including singles and doubles excitations (MR-CISD) and extensivity corrections (MR-CISD?+?Q) have been performed to study some low-lying valence and Rydberg states of the CF3 radical. Our highest level results (at the MR-CISD?+?Q level) yield the following energy ordering: 3s (7.90?eV)?2A2 (8.61?eV)?π (8.72?eV)?z (8.73?eV). MR-CISD results indicate transitions of similar intensities from the ground to the following three final states, in the following order: 3pπ?>?3pz?>?3s. It has also been found that the aforementioned Rydberg states should be responsible for visible emissions and correspond to transitions between bound states. Therefore, it is suggested that the lack of vibrational structure in the visible band of parent systems (e.g. CF3Cl) may be due to a transition from a bound to an unbound state of the parent molecule.  相似文献   

5.
The high-temperature form (HT) of the ternary germanide TbTiGe was prepared by melting. The investigation of HT-TbTiGe by x-ray and neutron powder diffractions shows that the compound crystallizes in the tetragonal CeScSi-type structure (space group I4/mmm; a?=?404.84(5) and c?=?1530.10(9)?pm as unit cell parameters). Magnetization and specific heat measurements as well as neutron powder diffraction performed on HT-TbTiGe reveal a ferromagnet having T(C)?=?300(1)?K as the Curie temperature; the Tb-moments are aligned along the c-axis. This magnetic ordering is associated with a modest magnetocaloric effect around room temperature. The isothermal magnetic entropy change ΔS(m) was determined from the magnetization data; ΔS(m) reaches, respectively, a maximum value of -?4.3 and -?2.0?J?K(-1)?kg(-1) for a magnetic field change of 5 and 2?T.  相似文献   

6.
Concentration of (222)Rn was determined in selected natural spring and tap water samples collected during spring and summer seasons from Kastamonu, Turkey. The aim of this work was to produce a map of the radon concentrations in water sources of the province and to determine any potential radiological risk for the local population. Radon measurements were performed by an AlphaGUARD radon gas analyser. The average radon concentrations were found to vary from 0.39±0.02 to 12.73±0.39?Bq?l(-1) for natural springs and from 0.36±0.04 to 9.29±0.45?Bq?l(-1) for tap water in spring, from 0.50±0.09 to 19.21±1.00?Bq?l(-1) for natural springs and from 0.31±0.03 to 13.14±0.38?Bq?l(-1) for tap water in summer. Furthermore, the results are compared with international recommendations and concentrations reported for other countries. Doses resulting from the consumption of these waters were calculated. The effective dose equivalents due to the intake of the (222)Rn present in these waters are expected to range from 0.93 to 32.54?μSv?y(-1) in summer and from 0.80 to 49.09?μSv?y(-1) in spring.  相似文献   

7.
The analysis of gamma-emitting radionuclides in nature, i.e. (226)Ra, (232)Th, (40)K and (137)Cs, has been carried out in soil samples collected from Peshawar University Campus and surrounding areas using a high purity germanium detector coupled with a computer-based high-resolution multichannel analyser. The activity concentrations in soil ranged from 30.20±0.65 to 61.90±0.95, 50.10±0.54 to 102.80±1.04, 373.60±4.56 to 1082±11.38 and 9.50±0.11 to 46.60±0.42?Bq?kg(-1) for (226)Ra, (232)Th, (40)K and (137)Cs, with a mean value of 45±7.70, 67±12.50, 878±180 and 19±9.20?Bq?kg(-1), respectively. The radium equivalent activity, internal and external hazard indices have mean values of 203.40±29.40?Bq?kg(-1), 0.56 and 0.68, respectively. The mean values of outdoor and indoor absorbed dose rates in air and the annual effective dose equivalents were found to be 106.50 and 128?nGy?h(-1) and 0.19 and 0.54?mSv?y(-1), respectively. In the present study, (40)K was the major radionuclide present in soil samples. The presence of (137)Cs indicates that this area also received some fallout from the nuclear accident of the Chernobyl power plant in 1986. The activity concentrations of radionuclides found in soil samples during the current investigation were nominal. Therefore, they are not associated with any potential source of health hazard to the public.  相似文献   

8.
We measure the top quark mass (m(t)) in p ?p collisions at a center of mass energy √s = 1.96 TeV using dilepton t ?t→W(+)bW(-) ?b→?(+)ν(?)b?(-) ?ν(?) ?b events, where ? denotes an electron, a muon, or a tau that decays leptonically. The data correspond to an integrated luminosity of 5.4 fb(-1) collected with the D0 detector at the Fermilab Tevatron Collider. We obtain m(t)=174.0±1.8(stat)±2.4(syst) GeV, which is in agreement with the current world average m(t)=173.3±1.1 GeV. This is currently the most precise measurement of m(t) in the dilepton channel.  相似文献   

9.
Radon concentration levels in water and soil gas from 36 locations pertaining to some areas of Malwa region of Punjab have been measured on an in situ basis using a continuous active radon detector (AlphaGuard, Model - PQ 2000 PRO, Genitron instruments, Germany). Exhalation rate measurements have also been carried out at these places, using a closed-circuit technique. The radon concentrations in soil and water varied from 1.9 to 16.4?kBq?m(-3) and 5.01 to 11.6?kBq?m(-3), respectively. The exhalation rate (E (Rn)) ranged between 7.48 and 35.88?mBq?m(-2)?s(-1) with an average value of 18.17?mBq?m(-2)?s(-1). Annual dose rates have been calculated for water radon concentrations. The minimum to maximum values of dose rates were found to be 13.42-31.08?μSv?y(-1). The recorded values of radon concentration in water are within the safe limit of 11?Bq?l(-1) recommended by the US Environment Protection Agency [National Research Council, Risk Assessment of Radon in Drinking Water (Academy Press, Washington, DC, USA, 1999)]. All measurements were made in similar climatic and environmental conditions to ensure minimal variations in meteorological parameters. An intermediate correlation coefficient (0.5) was observed between radon exhalation rates and soil gas values.  相似文献   

10.
By correlating the effects of substrate temperature, oxygen pressure and laser energy on the electrical and microstructural properties of Ag-doped ZnO films grown on a sapphire (0001) substrate, p-type conductivity is achieved under various substrate temperatures in the wide range of 250-750?°C. All of the samples were deposited by pulsed-laser deposition under various designed conditions. Hall measurements indicate that the best conductivity is achieved in Ag-ZnO films under a substrate temperature of 500?°C, a partial oxygen pressure of 250-300?mTorr and laser energy between 330 and 345?mJ. The hole-carrier concentration is 2.29?×?10(18)?cm(-3), the resistivity is 0.9?Ω?cm and the mobility is 3.03?cm(2)?V(-1)?s(-1). Transmission-electron microscopy (TEM) studies on the p-type films reveal similar microstructural properties to one another, but different properties to that of the n-type films deposited at the same temperatures with different deposition parameters.  相似文献   

11.
The objective of this study was to describe magnetic resonance (MR) findings with a 1.5T imager for hepatic parenchymal changes after proton beam radiotherapy. Thirty-two patients who received proton radiotherapy with doses of 50-87 Gy underwent MR imaging 1-75 months (mean 22 months) after the start of irradiation. Axial T(2), T(1)-weighted imaging, and a dynamic study after a gadolinium injection were performed. The irradiated areas showed hypointense in T(1)-weighted images, hyperintense in T(2)-weighted images, and intense and prolonged enhancement on the dynamic study (maximum relative enhancement 441.8%+/-263.3 vs. surrounding liver 145.6%+/-67.7, p<0.0001). T(2) values of the irradiated areas were 50.6 to 65.8 msec greater than in the surrounding liver (p<0.005). The values increased with time, being significantly greater 13 months or longer after the beginning of the therapy than after a period of less than 3 months (p<0.05). Pathologic examinations (n = 3) indicated that the irradiated areas were composed of collapsed lobules with hepatic small vein occlusions, and rich extracellular matrices which retained extracellular fluid. MR imaging can demonstrate hepatic parenchymal changes after proton beam radiotherapy, and show the changes are irreversible.  相似文献   

12.
Yi H  Liu K  Chen W  Tan T  Wang L  Gao X 《Optics letters》2011,36(4):481-483
We applied for the first time, to our knowledge, broadband off-beam quartz-enhanced photoacoustic spectroscopy (BB-OB-QEPAS) to trace NO2 detection using a broadband blue laser diode centered at 450?nm. A detection limit of 18?ppbv (parts in 10(9) by volume) for NO2 in N2 at atmospheric pressure was achieved with an average laser power of 7?mW at a 1?s integration time, which corresponds to a 1?σ normalized noise equivalent absorption coefficient of 4.1×10(-9) cm(-1)?W=Hz(1=2). An Allan variance analysis was performed to investigate the long-term stability of the BB-OB-QEPAS-based NO2 sensor.  相似文献   

13.
The orthogonal projectors from the space L(n) of n-fermion operators onto its sub-spaces Lp(n) consisting of p-reducible elements of L(n>), as well as those from L(n) onto Lp(n)?Lp?1(n) are constructed. Using the above projectors the inverse problems of contraction and expansion are solved.  相似文献   

14.
The aim of the study was to investigate the whole-body protein turnover, either before or after continuous, moderate ethanol-induced oxidative stress by red wine consumption over a relatively short period in healthy volunteers. Ten healthy adults received an individual regular diet over 20 days. After 10 days, the subjects consumed 0.4 ml ethanol kg(-1) day(-1) as red wine together with dinner over a 10-day period. After 8 and 18 days, respectively, a (15)N-labelled yeast protein was administered in a dosage of 4.2 mg kg(-1) body weight. Urine and faeces were collected over 48 h, respectively. The (15)N-enrichment was measured by isotope ratio mass spectrometry, whereas the protein flux rates were calculated by a three-compartment model. The whole-body protein turnover without/with red wine consumption amounted to 3.73±0.6 and 3.49±0.6 g kg(-1) day(-1) (not significant), respectively. Moderate alcohol consumption does not induce significant short-term changes in the whole-body protein turnover of healthy adults.  相似文献   

15.
We deal with the influence of the applied stress on the domain wall velocity in glass-coated magnetic microwires. In general, the domain wall velocity decreases with the applied tensile stress. Four regimes of the domain wall dynamics appear: (1)?diffusion-damped, (2)?a regime with variable domain wall width, (3)?a viscous and (4)?a vortex regime. Detailed analysis of domain wall parameters shows that the structural relaxation plays an important role even at ambient temperatures if high tensile stress is present. At higher fields (viscous regime), the most important damping arises from magnetic relaxation of magnetic moments. Finally, the domain wall velocity steeply increases (reaching a maximum at 7000?m?s(-1)) in the vortex regime and so does the domain wall mobility.  相似文献   

16.
In Rechna Doab, samples of the most common vegetation, perennial grass Desmostachya bipinnata (dab), were collected along with soil samples from 29 sites. Natural radioactivity of 22?Ra, 232Th/22?Ac and ??K was measured by using high purity germanium-based gamma ray spectrometer. Activity concentration levels of 22?Ra, 232Th/22?Ac and ??K in soil were found to be 46.8 ± 6.2 (36.0-57.6), 61.4 ± 5.9 (48.2-73.2) and 644.8 ± 73.9 (537.7-868.4) Bq kg?1 (dry mass), respectively, and those in vegetation were 2.74 ± 1.70 (1.00-6.39), 2.24 ± 0.59 (1.56-2.61) and 172.72±113.37 (53.14-469.24) Bq kg?1 (dry mass), respectively. The measured values of the activity concentration in vegetation are comparable with some other international data. Calculated soil to vegetation transfer factors of 22?Ra, 22?Ac and ??K were 0.06 ± 0.03 (0.02-0.14), 0.04 ± 0.01 (0.03-0.04) and 0.26 ± 0.16 (0.09-0.69). The mean outdoor absorbed dose rate in air for the area under study was determined as 8.22 nGy h?1 and the mean indoor absorbed dose rate in air was 11.52 nGy h?1. The total annual effective dose to the general public from the vegetation was found to be (0.02-0.16) mSv, which is below the recommended limit value of 1 mSv y?1 for the general public. The dab vegetation under study was found to be radiologically safe for the population and environment.  相似文献   

17.
The photoinduced dynamics of a dithienylethene chromophore coupled to the surface of TiO(2) by either a tripodal linker or a carboxyl group was investigated with ultrafast transient absorption spectroscopy. The absence of electron transfer from the photoexcited tripodal dithienylethene chromophore demonstrates that the tripod efficiently uncouples the electronic systems of dithienylethene and TiO(2). Contrary to this situation, photoinduced electron transfer can compete with ultrafast intramolecular relaxation in the COOH-dithienylethene/TiO(2) coupled system. An electron transfer rate of 1.1?×?10(12)?s(-1) can be extracted, which is considerably slower than the intramolecular relaxation rate of the dithienylethene (3.7?×?10(12)?s(-1)). Consequently, the electron transfer reaction exhibits a low efficiency.  相似文献   

18.
Methods have been developed to facilitate the data analysis of multiple two-dimensional powder diffraction images. These include, among others, automatic detection and calibration of Debye-Scherrer ellipses using pattern recognition techniques, and signal filtering employing established statistical procedures like fractile statistics.All algorithms are implemented in the freely available program package Powder3D developed for the evaluation and graphical presentation of large powder diffraction data sets.As a case study, we report the pressure dependence of the crystal structure of iron antimony oxide FeSb(2)O(4) (p≤21?GPa, T = 298?K) using high-resolution angle dispersive x-ray powder diffraction. FeSb(2)O(4) shows two phase transitions in the measured pressure range. The crystal structures of all modifications consist of frameworks of Fe(2+)O(6) octahedra and irregular Sb(3+)O(4) polyhedra. At ambient conditions, FeSb(2)O(4) crystallizes in space group P4(2)/mbc (phase I). Between p = 3.2?GPa and 4.1?GPa it exhibits a displacive second order phase transition to a structure of space group P 2(1)/c (phase II, a = 5.7792(4)??, b = 8.3134(9)??, c = 8.4545(11)??, β = 91.879(10)°, at p = 4.2?GPa). A second phase transition occurs between p = 6.4?GPa and 7.4?GPa to a structure of space group P4(2)/m (phase III, a = 7.8498(4)??, c = 5.7452(5)??, at p = 10.5?GPa). A nonlinear compression behaviour over the entire pressure range is observed, which can be described by three Vinet equations in the ranges from p = 0.52?GPa to p = 3.12?GPa, p = 4.2?GPa to p = 6.3?GPa and from p = 7.5?GPa to p = 19.8?GPa. The extrapolated bulk moduli of the high-pressure phases were determined to K(0) = 49(2)?GPa for phase I, K(0) = 27(3)?GPa for phase II and K(0) = 45(2)?GPa for phase III. The crystal structures of all phases are refined against x-ray powder data measured at several pressures between p = 0.52?GPa, and 10.5?GPa.  相似文献   

19.
The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using (3)He as a buffer gas. At T=1.8 K this allows for larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with (4)He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV?m(a)?0.64 eV. From the absence of excess x rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g(aγ)?2.3×10(-10) GeV(-1) at 95% C.L., the exact value depending on the pressure setting. Kim-Shifman-Vainshtein-Zakharov axions are excluded at the upper end of our mass range, the first time ever for any solar axion search. In the future we will extend our search to m(a)?1.15 eV, comfortably overlapping with cosmological hot dark matter bounds.  相似文献   

20.
《Physical review letters》2011,107(2):021802
A first measurement of the polarization of W bosons with large transverse momenta in pp collisions is presented. The measurement is based on 36 pb?1 of data recorded at √s = 7 TeV by the CMS detector at the LHC. The left-handed, right-handed, and longitudinal polarization fractions (f(L), f(R), and f?, respectively) of W bosons with transverse momenta larger than 50 GeV are determined by using decays to both electrons and muons. The muon final state yields the most precise measurement: (f(L) - f(R))? = 0.240 ± 0.036(stat) ± 0.031(syst) and f?? = 0.183 ± 0.087(stat) ± 0.123(syst) for negatively charged W bosons and (f(L) - f(R))? = 0.310 ± 0.036(stat) ± 0.017(syst) and f?? = 0.171 ± 0.085(stat) ± 0.099(syst) for positively charged W bosons. This establishes, for the first time, that W bosons produced in pp collisions with large transverse momenta are predominantly left-handed, as expected in the standard model.  相似文献   

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