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41.
Jörg M. Colberg Ravi K. Sheth Antonaldo Diaferio Liang Gao Naoki Yoshida 《Monthly notices of the Royal Astronomical Society》2005,360(1):216-226
We study the formation and evolution of voids in the dark matter distribution using various simulations of the popular Λ cold dark matter cosmogony. We identify voids by requiring them to be regions of space with a mean overdensity of −0.8 or less – roughly the equivalent of using a spherical overdensity group finder for haloes. Each of the simulations contains thousands of voids. The distribution of void sizes in the different simulations shows good agreement when differences in particle and grid resolution are accounted for. Voids very clearly correspond to minima in the smoothed initial density field. Apart from a very weak dependence on the mass resolution, the rescaled mass profiles of voids in the different simulations agree remarkably well. We find a universal void mass profile of the form ρ(< r )/ρ( r eff ) ∝ exp[( r / r eff )α ] , where r eff is the effective radius of a void and α∼ 2 . The mass function of haloes in voids is steeper than that of haloes that populate denser regions. In addition, the abundances of void haloes seem to evolve somewhat more strongly between redshifts ∼1 and 0 than the global abundances of haloes. 相似文献
42.
Ryoshi Ishiwatari Naoki Fujino David Brincat Shuichi Yamamoto Hikaru Takahara Koji Shichi Sergey K. Krivonogov 《Organic Geochemistry》2009,40(1):51-60
We characterized the compositions of organic compounds in a Cheremushka bog sediment core (deposited over the last 35 kyr), located at the eastern coast of Lake Baikal, to obtain basic information about the terrestrial organic matter (OM) which contributed to Lake Baikal sediments. The bog sediment was analyzed for the molecular composition of n-alkanes, lignin phenols and n-C24 to C30 alkanoic acids, as well as the carbon isotopic composition of plant wax derived n-C27 to C33 alkanes.Concentrations of lignin phenols [vanillyl (V) plus syringyl (S) phenols] normalized to total organic carbon (TOC) in the Holocene are twice those for the last glacial maximum (LGM), while concentrations of TOC-normalized n-C24 to C30 alkanoic acids do not change markedly in this period. Thus, the ratio of lignin phenols to n-C24 to C30 alkanoic acids increases from the LGM to the Holocene. This result is essentially consistent with pollen analysis indicating an expansion of woody plants in the Holocene and a prevailing herb-abundant environment for the LGM. The δ13C values of n-C27 to C33 alkanes (e.g. ?29‰ to ?33‰ for C31) indicate the presence of C3-dominant plants throughout the core.The contribution of terrestrial OM to Lake Baikal sediments was estimated using the biomarkers, on the assumption that the OM in the bog sediments is a representative of the terrestrial OM around the lake. Hence, the estimation using lignin phenol or n-C24 to C30 alkanoic acid parameters indicates that 11–24% of the TOC in the Academician Ridge sediments is land-derived for both the Holocene and the LGM, which is similar to the estimates from C/N values of bulk OM. However, the estimates for terrestrial OM using the n-C27 to C33 alkane parameter are generally higher than those using lignin phenol or n-C24 to C30 alkanoic acid parameters. The difference is thought to be associated with the difference in source and behavior of these biomarkers. 相似文献
43.
Two processes are generally explained as causes of temporal changes in the stoichiometric silicon/nitrogen (Si/N) ratios of
sinking particles and of nutrient consumption in the surface water during the spring diatom bloom: (1) physiological changes
of diatom under the stress of photosynthesis of diatom and (2) differences of regeneration between silicon and nitrogen. We
investigated which process plays an important role in these changes using a one-dimensional ecosystem model that explicitly
represents diatom and the other non-silicious phytoplankton. The model was applied to station A7 (41°30′ N, 145°30′ E) in
the western North Pacific, where diatom regularly blooms in spring. Model simulations show that the Si/N ratios of the flux
exported by the sinking particles at 100 m depth and of nutrient consumptions in the upper 100 m surface water have their
maxima at the end of the spring diatom bloom, the values and timings of which are significantly different from each other.
Analyses of the model results show that the differences of regeneration between silicon and nitrogen mainly cause the temporal
changes of the Si/N ratios. On the other hand, the physiological changes of diatoms under stress can hardly cause these temporal
changes, because the effect of the change in the diatom's uptake ratio of silicon to nitrogen is cancelled by that in its
sinking rate. 相似文献
44.
Observation of human-induced large-amplitude lateral vibration of an actual pedestrian bridge in an extremely congested condition is reported. Walking motions of pedestrians recorded by a video camera are analysed. It is found that walking among 20 per cent or more of the pedestrians on the bridge was synchronized to the girder lateral vibration. With this synchronization, the total lateral force from the pedestrians to the girder is evidently increased and it acts as a resonant force on the girder lateral vibration. 相似文献
45.
The heat capacity of åkermanite solid solutions was measured by a small scale adiabatic calorimeter near the incommensurate-normal (I-N) transition. The heat capacity anomalies caused by the I-N transition show the type characteristic behavior implying the presence of dynamical fluctuations. The heat capacity anomalies were observed over the whole range of the åkermanite solid solutions Ca2Mg1-xCoxSi2O7 and Ca2Mg1-x-ZnxSi2O2. With increase of Co or Zn atoms, the transition temperature, Ti, rises linearly from ca. 83° C to 220° C and to 130° C, respectively. In the system Ca2CoSi2O7-Ca2FeSi2O7 and Ca2MgSi2O7-Ca2-FeSi2O7 electronic microscopy revealed that the temperature of the heat capacity anomaly decreases with increasing Fe content, whereas the Ti rises. This unusual behavior is ascribed to the microdomains observed in high resolution lattice images. 相似文献
46.
Hirotaka Ito Motoki Kino Nozomu Kawakatu Naoki Isobe Shoichi Yamada 《Astrophysics and Space Science》2007,311(1-3):335-339
We investigate the total kinetic powers (L
j) and ages (t
age) of powerful jets of four FR II radio sources (Cygnus A, 3C 223, 3C 284, and 3C 219) by the detail comparison of the dynamical
model of expanding cocoons with observed ones. It is found that these sources have quite large kinetic powers with the ratio
of L
j to the Eddington luminosity (L
Edd) resides in 0.02<L
j/L
Edd<10. Reflecting the large kinetic powers, we also find that the total energy stored in the cocoon (E
c) exceed the energy derived from the minimum energy condition (E
min ): 2<E
c/E
min <160. This implies that a large amount of kinetic power is carried by invisible components such as thermal leptons (electron
and positron) and/or protons. 相似文献
47.
High temperature creep of single crystal gadolinium gallium garnet (GGG) was studied in the temperature range of 1723–1853 K (0.86–0.94 Tm, Tm: melting temperature) and strain rate from 9 · 10?7 s?1 to 2 · 10?5 s?1. The compression tests were made along the 〈100〉 and 〈111〉 orientations. We have performed both constant strain-rate and stress-dip tests. For the 〈100〉 orientation, deformation occurs via the 〈111〉 slip systems. For the 〈111〉 orientation, both the 〈100〉 {010} and the 〈111〉 slip systems can be activated. GGG garnet is very strong under these conditions: σ/μ=(1–3)×10?3 (σ: creep strength, μ: shear modulus). The creep behavior is characterized by a power law with stress exponent n=2.9–3.3 and high activation energies E*=612–743 kJ/mol (E*~45×RTm, at zero stress which decrease with the increase of stress). Stress-dip tests suggest a small internal stress (σi/σ~0.62; σi: internal stress, σ: applied stress) compared to other materials. These results suggest that the high creep strength of GGG is mainly due to difficulty of dislocation glide rather than dislocation climb. 相似文献
48.
Yoshihiro Hidaka Naoki Shirai Akira Yamaguchi Mitsuru Ebihara 《Meteoritics & planetary science》2019,54(5):1153-1166
We have studied magnetic fractions of five acapulcoites, three lodranites, and two winonaites to investigate chemical compositions of their precursor materials and metallic partial melting processes occurring on their parent bodies. One winonaite metal is similar in composition to low Au, low Ni IAB iron subgroup, indicating genetic relationship between them. Magnetic fractions of chondrule‐bearing acapulcoite and winonaite have intermediate chemical compositions of metals between H chondrites and EL chondrites. This fact indicates that the precursor materials of acapulcoite–lodranites and winonaites were similar to H and/or EL chondrites in chemical compositions. Magnetic fractions in acapulcoite–lodranites have a large variety of chemical compositions. Most of them show enrichments of W, Re, Ir, Pt, Mo, and Rh, and one of them shows clear depletion in Re and Ir relative to those of chondrule‐bearing acapulcoite. Chemical compositional variations among acapulcoite–lodranite metals cannot be explained by a single Fe‐Ni‐S partial melting event, but a two‐step partial melting model can explain it. 相似文献
49.
Simple monitoring method for precaution of landslides watching tilting and water contents on slopes surface 总被引:2,自引:2,他引:0
Taro Uchimura Ikuo Towhata Trinh Thi Lan Anh Jou Fukuda Carlos J. B. Bautista Lin Wang Ichiro Seko Taro Uchida Akira Matsuoka Yosuke Ito Yuichi Onda Sho Iwagami Min-Seok Kim Naoki Sakai 《Landslides》2010,7(3):351-357
A low-cost and simple monitoring method for early warning of landslides is proposed. To detect abnormal deformation of a slope, this method employs a tilt sensor in place of an extensometer on the slope surface. In order to examine the relevance of measuring rotation angle on a slope surface by tilt sensor, model tests were conducted, and rotation on the slope surface was observed together with slide displacement along the surface. The rotation data responded 30 min before failure in a model test, which could be useful as a signal for early warning. However, the behavior of rotation before failure varies from case to case, and thus, criteria to issue warning should be defined more carefully. For a model slope made of uniform loose sand, measurement of slide displacement along the slope surface is sensitive to failure at the toe, while the measurement of rotation on the slope surface is useful to detect the development of progressive failure upward along the slope. Wireless sensor units with microelectromechanical systems (MEMS) tilt sensor and volumetric water content sensor were also examined on a real slope in Kobe City, and a long-term monitoring was attempted. A simple but possible way to define the criteria of judgment to issue warning can be proposed based on combination of data obtained by the tilt sensors and volumetric water content sensors. 相似文献
50.
Abstract Recent advanced chronological studies for the Tertiary volcanic rocks from the Northeast (NE) Japan arc revealed three volcanic fronts which differed in temporal and spatial distribution. These fronts were (i) the Matsumae-Shizukuishi-Shiogama line of 22–25 Ma which is obliquely across the Quaternary volcanic front (QVF); (ii) the Tomari-Shiogama line of 13–16 Ma which exists 30–50 km east of the QVF and (iii) a line of 0–8 Ma which is the same as the QVF. The first shifting of the 22–25 Ma line to the 13–16 Ma one was due to the counterclockwise rotation of the NE Japan arc during 20–12 Ma as proposed by Otofuji et al . (1985), and the second shifting of the 13–16 Ma line to the 0–8 Ma line could have contributed to a decrease in the dip of the slab of the Pacific plate which subducted beneath the NE Japan arc during 13–8 Ma. 相似文献