57 research outputs found
MagnitudeâFrequency Distribution of Slope Failures in Japan: Statistical Approach to a True Perspective on Volcanic MegaâCollapses
The relationship between magnitude and frequency of megaâcollapses (i.e., sector collapses), mainly of volcanic edifices, in Japan is examined by using existing datasets for volcanic megaâcollapses and smaller but more frequent events. Statistical analysis of these datasets showed that the magnitudeâfrequency distribution of slope failures with volumes greater than or equal to 107 m3 can be expressed by a simple exponential function: logN(x) = a â bx, where N(x) is the cumulative number of massâmovement events with magnitude â„x. When this function was fitted to the datasets, the slope coefficient, b, was 0.7 or 0.8. The frequency distribution of megaâcollapses was similar to that of smaller (volume >105â6 m3) events. Records from the past millennium in Japan suggest that this magnitudeâfrequency relationship may be applicable to the last several tens of thousands of years. Therefore, it is possible to predict event probability and the recurrence interval of events of a certain magnitude. In this way, megaâcollapses with a volume of over 109 m3 may be estimated to occur at least every 1000â2000 years somewhere in Japan. Therefore, megaâcollapses in Japan should not be considered ârareâ; rather, they are ânormalâ events on a geomorphological timescale
Results of the search for inspiraling compact star binaries from TAMA300's observation in 2000-2004
We analyze the data of TAMA300 detector to search for gravitational waves
from inspiraling compact star binaries with masses of the component stars in
the range 1-3Msolar. In this analysis, 2705 hours of data, taken during the
years 2000-2004, are used for the event search. We combine the results of
different observation runs, and obtained a single upper limit on the rate of
the coalescence of compact binaries in our Galaxy of 20 per year at a 90%
confidence level. In this upper limit, the effect of various systematic errors
such like the uncertainty of the background estimation and the calibration of
the detector's sensitivity are included.Comment: 8 pages, 4 Postscript figures, uses revtex4.sty The author list was
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Observation results by the TAMA300 detector on gravitational wave bursts from stellar-core collapses
We present data-analysis schemes and results of observations with the TAMA300
gravitational-wave detector, targeting burst signals from stellar-core collapse
events. In analyses for burst gravitational waves, the detection and
fake-reduction schemes are different from well-investigated ones for a
chirp-wave analysis, because precise waveform templates are not available. We
used an excess-power filter for the extraction of gravitational-wave
candidates, and developed two methods for the reduction of fake events caused
by non-stationary noises of the detector. These analysis schemes were applied
to real data from the TAMA300 interferometric gravitational wave detector. As a
result, fake events were reduced by a factor of about 1000 in the best cases.
The resultant event candidates were interpreted from an astronomical viewpoint.
We set an upper limit of 2.2x10^3 events/sec on the burst gravitational-wave
event rate in our Galaxy with a confidence level of 90%. This work sets a
milestone and prospects on the search for burst gravitational waves, by
establishing an analysis scheme for the observation data from an
interferometric gravitational wave detector
Angular distribution control of extreme ultraviolet radiation from laser-produced plasma by manipulating the nanostructure of low-density SnO 2 targets
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±ć”æšéČæ©æ§We have found that the divergence of a relatively monochromatic extreme ultraviolet (EUV) emission from a laser-produced plasma can be manipulated by changing the target morphology which is a porous low-density tin oxide (Sn O2) structure. The fundamental light of a Nd-YAG laser was irradiated on the target with laser intensity of ⌠1011 W cm2 and pulse duration of 10 ns. The nanostructure and density of the targets were tuned by a combination of colloidal polymer template and sol-gel processes [Gu, Nagai, Norimatsu, Fujioka, Nishimura, Nishihara, Miyanaga, and Izawa, Chem. Mater. 17, 1115 (2005)], which has a merit in large-scale preparation. When the target has an open cell nanostructure, the EUV emission directed predominantly along target normal, while a closed cell target exhibited divergent emission. The angular distribution may be affected by the orientation of the microstructured initial target, and this phenomenon can be applied to wavefront control of EUV emission. © 2006 American Institute of Physics.Embargo Period 12 month
Finishing the euchromatic sequence of the human genome
The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers âŒ99% of the euchromatic genome and is accurate to an error rate of âŒ1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead
Comment on âImpact of â24 ka Nakanojo Mud Flow' Event on the Fluvial Landform Development in Nakanojo Basin, Central Japanâ
High Beam Quality for High-Average-Power Laser System Using Phase Conjugation Mirrors - Stimulated Brillouin Scattering from Optical Fiber to Fused-Silica Glass -
Base Level of the âNakanojo Mudflow Depositsâ at Nakanojo Basin-Reply to the Comments by H. Takemoto on âImpact of â24 ka Nakanojo Mud Flow' Event on the Fluvial Landform Development in Nakanojo Basin, Central Japanâ
Magnitude-Frequency Distribution of Hummocks on Rockslide-Debris Avalanche Deposits and Its Geomorphological Significance
A magnitude-frequency analysis of rockslide-debris avalanche deposits was performed. Hummocks are conical mounds formed in debris avalanche deposits from the catastrophic sector collapse of a mountain (often volcanic) that represent relatively cohesive fragments of the mountain edifice. Examination of 17 debris avalanche deposits in Japan and the Philippines showed that, in general, the larger the magnitude of the hummocks, the smaller their frequency. Hummocks followed an exponential distribution: log10N(x) = a â bx, where N(x) is the cumulative number of hummocks with magnitude â„ x and a and b are constants; x is equal to log10A, where A is the area of a hummock. The constants a and b were positively correlated. The value of b, which differs among avalanches and in this analysis ranged between 1 and 3, may be controlled by the mobility of the debris avalanche. Avalanches with higher mobility (relatively longer runout) have higher b and potentially produce more numerous fragments forming hummocks (i.e., higher a). From the above correlation, the magnitude-frequency relationship can be used to roughly estimate the original height of the collapsed volcanic body, if the runout distance of the rockslideâdebris avalanche can be estimated with sufficient accuracy
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