Stable hydrogen isotope measurement of archaeal ether-bound hydrocarbons     

Masanori KanekoFumio Kitajima  Hiroshi Naraoka 《Organic Geochemistry》2011,42(2):166-172

Compound-specific hydrogen isotope analysis of ether-bound isoprenoid hydrocarbons from archaeal membranes has been developed using chemical degradation and gas chromatography/pyrolysis/isotope ratio mass spectrometry. The ether-bound hydrocarbons are quantitatively converted to saturated hydrocarbons by cleavage of ether bonds with HI followed by H₂ reduction in the presence of PtO₂. The δD value of ether-bound hydrocarbon moieties are corrected by way of isotopic mass balance calculation for the hydrogen incorporated during the hydrogenation. The method was successfully applied to determination of the δD values of biphytane moieties in glycerol dialkyl glycerol tetraethers (GDGTs) from a Sulfolobus sp. culture and a marine sediment.  相似文献   

Regional long-term production modeling from a single well test, Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope   总被引：1，自引：0，他引：1  

Brian J. Anderson  Masanori KuriharaMark D. White  George J. MoridisScott J. Wilson  Mehran Pooladi-DarvishManohar Gaddipati  Yoshihiro MasudaTimothy S. Collett  Robert B. HunterHideo Narita  Kelly RoseRay Boswell 《Marine and Petroleum Geology》2011,28(2):493-501

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Statistical distribution of gravitational-lensing excursion angles: winding ways to us from the deep Universe     

Takashi Hamana  Matthias Bartelmann  Naoki Yoshida  Christoph Pfrommer 《Monthly notices of the Royal Astronomical Society》2005,356(3):829-838

We investigate statistical distributions of differences in gravitational-lensing deflections between two light rays, the so-called lensing excursion angles. A probability distribution function of the lensing excursion angles, which plays a key role in estimates of lensing effects on angular clustering of objects (such as galaxies, quasi-stellar objects and also the cosmic microwave background temperature map), is known to consist of two components: a Gaussian core and an exponential tail. We use numerical gravitational-lensing experiments in a ΛCDM cosmology for quantifying these two components. We especially focus on the physical processes responsible for generating these two components. We develop a simple empirical model for the exponential tail which allows us to explore its origin. We find that the tail is generated by the coherent lensing scatter by massive haloes with   M > 10¹⁴  h ⁻¹ M_⊙  at   z < 1  and that its exponential shape arises due to the exponential cut-off of the halo mass function at that mass range. On scales larger than 1 arcmin, the tail does not have a practical influence on the lensing effects on the angular clustering. Our model predicts that the coherent scatter may have non-negligible effects on angular clustering at subarcminute scales.  相似文献   

Modelling peculiar velocities of dark matter haloes     

Takashi Hamana  Issha Kayo  Naoki Yoshida  Yasushi Suto  Y. P. Jing 《Monthly notices of the Royal Astronomical Society》2003,343(4):1312-1318

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The influence of the brightness of the asteroidal dust bands on the gegenschein     

Tadashi Mukai  Masanori Fujino  Ryosuke Nakamura  Fumihiko Usui 《Icarus》2003,162(2):337-343

The position and shape of the Gegenschein’s maximum brightness provide information on the structure of the interplanetary dust cloud. We show that the asteroidal dust bands, extended near the anti-solar point, play an important role in determining both the position of the maximum brightness and the shape of the Gegenschein. After removing the asteroidal dust bands from an observation of the Gegenschein on November 2, 1997, it was found that the maximum brightness point shifted −0.4° in ecliptic latitude, i.e., to the south of the ecliptic plane, at an ecliptic longitude of 180°, in contrast to a latitude value of +0.1° when the dust bands were included. Furthermore, the part of the Gegenschein to the south of the ecliptic plane was brighter than the northern part at the time of observation. Referring to the cloud model of T. Kelsall et al. (1998, Astrophy. J. 508, 44-73), it can be estimated that the ascending node of the symmetry plane of the dust cloud is 57°^−3°_+7° when its inclination is 2.03° ? 0.50°.  相似文献   

High-temperature Raman spectroscopy and quasi-harmonic lattice dynamic simulation of diopside     

Varghese Swamy  Leonid S. Dubrovinsky  Masanori Matsui 《Physics and Chemistry of Minerals》1997,24(6):440-446

We investigated the lattice vibrational properties and lattice dynamical behaviour of diopside by combining laser micro-Raman spectroscopic measurements with quasi-harmonic lattice dynamic simulation using a transferable interatomic potential. We obtained polarized Raman spectra from a Fe-poor natural diopside and the temperature dependencies of the Raman modes to 1125?K from high-temperature Raman spectra of a Fe-poor and a Fe-rich natural diopside. The various modes display different temperature dependencies: from ?0.021?cm^?1/K to ?0.004?cm^?1/K. The temperature shift of low frequency modes is generally higher. A comparison of experimentally determined frequencies and symmetries of vibrational modes of the optical type (Raman and infrared) obtained in this and earlier studies with those calculated by us suggests that a consistent characterization of the vibrational properties was achieved. The good agreement between the experimental and simulated data on the temperature-dpendencies of the Raman modes (within 5%), crystal structure (2%), bulk modulus (5%), volume thermal expansivity (6%), and constant volume heat capacity (0.2%) testifies to the applicability of the transferable interatomic potential and the lattice dynamic model to predicting the vibrational, physical, and thermodynamic properties. The simulated properties from the lattice dynamic calculations are very similar to those obtained by molecular dynamic calculations with the same potential model.  相似文献   

Quasi-radial modes of rotating stars in general relativity     

Shin'ichirou Yoshida  Yoshiharu Eriguchi 《Monthly notices of the Royal Astronomical Society》2001,322(2):389-396

By using the Cowling approximation, quasi-radial modes of rotating general relativistic stars are computed along equilibrium sequences from non-rotating to maximally rotating models. The eigenfrequencies of these modes are decreasing functions of the rotational frequency. The eigenfrequency curve of each mode as a function of the rotational frequency has discontinuities, which arise from the avoided crossing with other curves of axisymmetric modes.  相似文献   

Oscillations of vertically integrated relativistic tori – I. Axisymmetric modes in a Schwarzschild space–time     

Luciano Rezzolla  Shin'ichirou Yoshida  Olindo Zanotti 《Monthly notices of the Royal Astronomical Society》2003,344(3):978-992

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The Structure of Young Stellar Jets and Winds Revealed by High Resolution [Fe II] λ1.644μm Line Observations     

Tae-Soo Pyo  Masahiko Hayashi  Naoto Kobayashi  Alan T. Tokunaga  Hiroshi Terada  Miwa Goto  Takuya Yamashita  Yoichi Itoh  Hideki Takami  Naruhisa Takato  Yutaka Hayano  Wolfgang Gaessler  Yukiko Kamata  Yosuke Minowa  Masanori Iye 《Astrophysics and Space Science》2003,287(1-4):21-24

We present high angular resolution spectra taken along the jets from L1551 IRS 5 and DG Tau obtained with the Subaru Telescope. The position-velocity diagrams of the [Fe II] λ 1.644 μmemission line revealed remarkably similar characteristics for the two sources, showing two distinct velocity components separated from each other in both velocity and space with the entire emission range blueshifted with respect to the stellar velocity. The high velocity component (HVC) has a velocity of –200 ––300 km s^-1 with a narrow line width, while the low velocity component (LVC) is around –100 km s^-1 exhibitinig a broad line width. The HVC is located farther away from the origin and is more extended than the LVC. Our results suggest that the HVC is a well-collimated jet originating from the region close to the star, while the LVC is a widely-opened wind accelerated in the region near the inner edge of the accretion disk.  相似文献   

Can non-Gaussian cosmological models explain the WMAP high optical depth for reionization?     

Xuelei Chen  Asantha Cooray  Naoki Yoshida  Naoshi Sugiyama 《Monthly notices of the Royal Astronomical Society》2003,346(3):L31-L35

The first-year Wilkinson Microwave Anisotropy Probe data suggest a high optical depth for Thomson scattering of  0.17 ± 0.04  , implying that the Universe was reionized at an earlier epoch than previously expected. Such early reionization is likely to be caused by ultraviolet (UV) photons from first stars, but it appears that the observed high optical depth can be reconciled within the standard structure formation model only if star formation in the early Universe was extremely efficient. With normal star formation efficiencies, cosmological models with non-Gaussian density fluctuations may circumvent this conflict as high density peaks collapse at an earlier epoch than in models with Gaussian fluctuations. We study cosmic reionization in non-Gaussian models and explore to what extent, within available constraints, non-Gaussianities affect the reionization history. For mild non-Gaussian fluctuations at redshifts of 30 to 50, the increase in optical depth remains at a level of a few per cent and appears unlikely to aid significantly in explaining the measured high optical depth. On the other hand, within available observational constraints, increasing the non-Gaussian nature of density fluctuations can easily reproduce the optical depth and may remain viable in underlying models of non-Gaussianity with a scale-dependence.  相似文献