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141.
Akira Tsuchiyama Masayuki Uesugi Kentaro Uesugi Tsukasa Nakano Ryo Noguchi Toru Matsumoto Junya Matsuno Takashi Nagano Yuta Imai Akira Shimada Akihisa Takeuchi Yoshio Suzuki Tomoki Nakamura Takaaki Noguchi Masanao Abe Toru Yada Akio Fujimura 《Meteoritics & planetary science》2014,49(2):172-187
In this study, the three‐dimensional (3‐D) microstructure of 48 Itokawa regolith particles was examined by synchrotron microtomography at SPring‐8 during the preliminary examination of Hayabusa samples. Moreover, the 3‐D microstructure of particles collected from two LL6 chondrites (Ensisheim and Kilabo meteorites) and an LL5 chondrite (Tuxtuac meteorite) was investigated by the same method for comparison. The modal abundances of minerals, especially olivine, bulk density, porosity, and grain size are similar in all samples, including voids and cracks. These results show that the Itokawa particles, which are surface materials from the S‐type asteroid Itokawa, are consistent with the LL chondrite materials in terms of not only elemental and isotopic composition of the minerals but also 3‐D microstructure. However, we could not determine whether the Itokawa particles are purely LL5, LL6, or a mixture of the two. No difference between the particles collected from Rooms A and B of the sample chamber, corresponding to the sampling sequence of the spacecraft's second and first touchdowns, respectively, was detected because of the statistically small amount of particles from Room B. 相似文献
142.
Hidetaka Nomaki Naohiko Ohkouchi Petra Heinz Hisami Suga Yoshito Chikaraishi Nanako O. Ogawa Kouhei Matsumoto Hiroshi Kitazato 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(9):1488-1503
We conducted an in situ feeding experiment using 13C-labeled unicellular algae in Sagami Bay, Japan (water depth, 1450 m), in order to understand the fate of lipid compounds in phytodetritus at the deep-sea floor. We examined the incorporation of excess 13C into lipid compounds extracted from bulk sediments and benthic foraminiferal cells. 13C-enriched fatty acids derived from 13C-labeled algae were exponentially degraded during 6 days of incubation in the sediment. Subsequent enrichments in 13C in sedimentary n-C15, anteiso-C17, and C17 fatty acids indicated the microbial degradation of algal material and production of bacterial biomass in the sediment. We observed the incorporation of 13C-labeled algal phytol and fatty acids into foraminiferal cells. The compositions of 13C-labeled algal lipids in foraminiferal cells were different from those in the bulk sediments, indicating that foraminiferal feeding and digestion influenced the lipid distribution in the sediments. Furthermore, some sterols in Globobulimina affinis (e.g., 24-ethylcholesta-5,22-dien-3β-ol, 24-ethylcholest-5-en-3β-ol, and 23,24-dimethylcholesta-5,22E-dien-3β-ol) were newly produced via the modification of dietary algal sterols within 4–6 days. In addition to the effects of bacteria, feeding by benthic foraminifera can result in a significant reorganization of the composition of organic matter and influence benthic food webs and carbon cycling at the deep-sea floor. 相似文献
143.
H. Sugai T. Usuda H. Kawabata M. Y. Inoue H. Kataza M. Tanaka 《Experimental Astronomy》1994,3(1-4):315-316
We have developed a near-infrared Fabry-Perot imager at the Nasmyth focus of the Communications Research Laboratory (CRL) 1.5 m telescope at Tokyo. Using this wide field Fabry-Perot imager, we obtained continuum-subtracted images of the H2
v=1–0 S(1) line for the Orion KL region. 相似文献
144.
145.
A simplified method of numerical analysis based on elasticity theory has been developed for the analysis of axially and laterally loaded piled raft foundations embedded in non‐homogeneous soils and incorporated into a computer program “PRAB”. In this method, a hybrid model is employed in which the flexible raft is modelled as thin plates and the piles as elastic beams and the soil is treated as springs. The interactions between structural members, pile–soil–pile, pile–soil–raft and raft–soil–raft interactions, are approximated based on Mindlin's solutions for both vertical and lateral forces with consideration of non‐homogeneous soils. The validity of the proposed method is verified through comparisons with some published solutions for single piles, pile groups and capped pile groups in non‐homogeneous soils. Thereafter, the solutions from this approach for the analysis of axially and laterally loaded 4‐pile pile groups and 4‐pile piled rafts embedded in finite homogeneous and non‐homogeneous soil layers are compared with those from three‐dimensional finite element analysis. Good agreement between the present approach and the more rigorous finite element approach is demonstrated. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
146.
147.
We present three-dimensional numerical simulations on binary formation through fragmentation. The simulations follow gravitational collapse of a molecular cloud core up to growth of the first core by accretion. At the initial stage, the gravity is only slightly dominant over the gas pressure. We made various models by changing initial velocity distribution (rotation speed, rotation law, and bar-mode perturbation). The cloud fragments whenever the cloud rotates sufficiently slowly to allow collapse but faster enough to form a disk before first-core formation. The latter condition is equivalent to Ω0 t ff ? 0.05, where Ω0 and t ff f denote the initial central angular velocity and the freefall time measured from the central density, and the condition is independent of the initial rotation law and bar-mode perturbation. Fragmentation is classified into six types. When the initial cloud rotates rigidly the cloud collapses to form a adiabatic disk supported by rotation. When the bar-mode perturbation is very minor, the disk deforms to a rotating bar, and the bar fragments. Otherwise, the adiabatic disk evolves into a central core surrounded by a circumstellar disk, and the the circumstellar disk fragments. When the initial cloud rotates differentially, the cloud deforms to a ring or bar in the isothermal collapse phase. The ring fragments into free or more cores, while the bar fragments into only two cores. In the latter case, the core merges due to low orbital angular momentum and new satellite cores form in the later stages. 相似文献
148.
Carlos Roberto Sanquetta Ana Paula Dalla Corte Alexandre Behling Luani Rosa de Oliveira Piva Sylvio Péllico Netto Aurélio Lourenço Rodrigues Mateus Niroh Inoue Sanquetta 《Carbon balance and management》2018,13(1):25
Background
Biomass models are useful for several purposes, especially for quantifying carbon stocks and dynamics in forests. Selecting appropriate equations from a fitted model is a process which can involves several criteria, some widely used and others used to a lesser extent. This study analyzes six selection criteria for models fitted to six sets of individual biomass collected from woody indigenous species of the Tropical Atlantic Rain Forest in Brazil. Six models were examined and the respective fitted equations evaluated by the residual sum of squares, adjusted coefficient of determination, absolute and relative estimates of the standard error of estimate, and Akaike and Schwartz (Bayesian) information criteria. The aim of this study was to analyze the numeric behavior of these model selection criteria and discuss the ease of interpretation of them. The importance of residual analysis in model selection is stressed.Results
The adjusted coefficient of determination (\( R^{2}_{adj.} \)) and the standard error of estimate in percentage (Syx%) are relative model selection criteria and are not affected by sample size and scale of the response variable. The sum of squared residuals (SSR), the absolute standard error of estimate (Syx), the Akaike information criterion and the Schwartz information criterion, in turn, depend on these quantities. The best fit model was always the same within a given data set regardless the model selection criteria considered (except for SSR in two cases), indicating they tend to converge to a common result. However, such criteria are not always closely related across different data sets. General model selection criteria are indicative of the average goodness of fit, but do not capture bias and outlier effects. Graphical residual analysis is a useful tool to this detection and must always be used in model selection.Conclusions
It is concluded that the criteria for model selection tend to lead to a common result, regardless their mathematical formulation and statistical significance. Relative measures of goodness of fitting are easier to interpret than the absolute ones. Careful graphical residual analysis must always be used to confirm the performance of the models.149.
I. S. Glass S. Matsumoto B. S. Carter K. Sekiguchi 《Monthly notices of the Royal Astronomical Society》2001,321(1):77-95
We report here the results of a 4-yr K -band (2.2 μm) survey for large-amplitude variable stars in a area centred on the Galactic Centre. A total of 409 likely long-period variables (LPVs) were detected, for which positions, amplitudes, average magnitudes and periods were obtained whenever possible. The surface density of LPVs is more than ten times greater than in the Sgr I Baade window at
The limits of completeness arising from interstellar and circumstellar absorption are discussed. Most of the area suffers interstellar extinction of The shorter-period LPVs are less luminous than the longer-period ones and may be slightly under-represented in the data. Extremely heavy extinction which affects the probability of detecting variables, occurs in less than 25 per cent of the area.
Almost all of the LPVs are Miras or OH/IR stars, with periods ranging from 150 d to about 800 d. K -band counterparts have been found for 59 per cent of the 109 known OH sources in the field. The average period of the variables found is 427 d, while that of the OH/IR stars is 524 d. For comparison, the average period in the Sgr I window, which contains no known OH/IR stars, is 333 d and only two stars are detected with The survey field also contains a number of long-period, large-amplitude variables that are not OH emitters. 相似文献
The limits of completeness arising from interstellar and circumstellar absorption are discussed. Most of the area suffers interstellar extinction of The shorter-period LPVs are less luminous than the longer-period ones and may be slightly under-represented in the data. Extremely heavy extinction which affects the probability of detecting variables, occurs in less than 25 per cent of the area.
Almost all of the LPVs are Miras or OH/IR stars, with periods ranging from 150 d to about 800 d. K -band counterparts have been found for 59 per cent of the 109 known OH sources in the field. The average period of the variables found is 427 d, while that of the OH/IR stars is 524 d. For comparison, the average period in the Sgr I window, which contains no known OH/IR stars, is 333 d and only two stars are detected with The survey field also contains a number of long-period, large-amplitude variables that are not OH emitters. 相似文献
150.
Tsunami deposit associated with the 2011 Tohoku‐oki tsunami in the Hasunuma site of the Kujukuri coastal plain,Japan
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Dan Matsumoto Yuki Sawai Koichiro Tanigawa Osamu Fujiwara Yuichi Namegaya Masanobu Shishikura Kyoko Kagohara Haruo Kimura 《Island Arc》2016,25(5):369-385
We describe the detailed sedimentary characteristics of a tsunami deposit associated with the 2011 Tohoku‐oki tsunami in Hasunuma, a site on the Kujukuri coastal plain, Japan. The thick tsunami deposit was limited to within 350 m from the coastline whereas the inundation area extended about 1 km from the coastline. The tsunami deposit was sampled by excavation at 29 locations along three transects and studied using peels, soft‐X imaging and grain‐size analysis. The deposit covers the pre‐existing soil and reached a maximum measured thickness of 35 cm. It consists mainly of well‐sorted medium to fine sand. On the basis of sedimentary structures and changes in grain size, we divided the tsunami deposit into several sedimentary units, which may correspond to multiple inundation flows. The numbers of units and their sedimentary features vary among the three transects, despite the similar topography. This variation implies a considerable influence of local effects such as elevation, vegetation, microtopography, and distance from footpaths, on the tsunami‐related sedimentation. 相似文献