713 research outputs found
ASCA Observations of Two Ultra-Luminous Compact X-Ray Sources in the Edge-on Spiral Galaxy NGC 4565
The edge-on spiral galaxy NGC 4565 was observed for 35 ks with ASCA in
the 0.5-10 keV energy band. The X-ray emission was dominated by two bright
sources, which can be identified with two point-like X-ray sources seen in the
ROSAT HRI image. The observed 0.5-10 keV fluxes of these sources, and , % % imply bolometric
luminosities of and ,
respectively. They exhibit similar spectra, which can be explained by emission
from optically thick accretion disks with the inner disk temperature of 1.4-1.6
keV. One of them, coincident in position with the nucleus, shows too low
absorption to be the active nucleus seen through the galaxy disk. Their spectra
and high luminosities suggest that they are both mass accreting black hole
binaries. However the black-hole mass required by the Eddington limit is rather
high (), and the observed disk temperature is too high to be
compatible with the high black-hole mass. Several attempts are made to solve
these problesms.Comment: 20page
Untangling the complexity of market competition in consumer goods -A complex Hilbert PCA analysis
Today's consumer goods markets are rapidly evolving with significant growth
in the number of information media as well as the number of competitive
products. In this environment, obtaining a quantitative grasp of heterogeneous
interactions of firms and customers, which have attracted interest of
management scientists and economists, requires the analysis of extremely
high-dimensional data. Existing approaches in quantitative research could not
handle such data without any reliable prior knowledge nor strong assumptions.
Alternatively, we propose a novel method called complex Hilbert principal
component analysis (CHPCA) and construct a synchronization network using Hodge
decomposition. CHPCA enables us to extract significant comovements with a time
lead/delay in the data, and Hodge decomposition is useful for identifying the
time-structure of correlations. We apply this method to the Japanese beer
market data and reveal comovement of variables related to the consumer choice
process across multiple products. Furthermore, we find remarkable customer
heterogeneity by calculating the coordinates of each customer in the space
derived from the results of CHPCA. Lastly, we discuss the policy and managerial
implications, limitations, and further development of the proposed method.Comment: 27 pages with 9 Figures and 7 Tables, including a 2-page Appendi
An integrated stratigraphy around the Plio-Pleistocene boundary in the Chikura Group, the Boso Peninsula, central Japan, based on data from paleomagnetic, oxygen isotopic and widespread tephra correlation
As widespread tephra is considered to have been deposited widely in an extremely short time after volcanic eruption, it has an important role as a useful geological time index. To improve the accuracy of tephrochronology, we propose a widespread tephra correlation based on various characteristics of the tephra layers for the middle section of the Chikura Group from the southernmost part of the Boso Peninsula, Japan, with a refined chronorostratigraphy based on magnetostratigraphy and oxygen isotopic stratigraphic analysis of benthic foraminifers. Around the Plio-Pleistocene boundary, we were able to compare seven tephra layers with the other tephra layers in Plio-Pleistocene strata in central Japan, and were able to obtain a detailed tephrochronology. The improved accuracy of the integrated tephrochronology is expected to contribute to the understanding of environmental changes over time
Phenotypic Characterization of Transgenic Mice Overexpressing Neuregulin-1
BACKGROUND: Neuregulin-1 (NRG1) is one of the susceptibility genes for schizophrenia and implicated in the neurotrophic regulation of GABAergic and dopaminergic neurons, myelination, and NMDA receptor function. Postmortem studies often indicate a pathologic association of increased NRG1 expression or signaling with this illness. However, the psychobehavioral implication of NRG1 signaling has mainly been investigated using hypomorphic mutant mice for individual NRG1 splice variants. METHODOLOGY/PRINCIPAL FINDINGS: To assess the behavioral impact of hyper NRG1 signaling, we generated and analyzed two independent mouse transgenic (Tg) lines carrying the transgene of green fluorescent protein (GFP)-tagged type-1 NRG1 cDNA. The promoter of elongation-factor 1α gene drove ubiquitous expression of GFP-tagged NRG1 in the whole brain. As compared to control littermates, both heterozygous NRG1-Tg lines showed increased locomotor activity, a nonsignificant trend toward decreasing prepulse inhibition, and decreased context-dependent fear learning but exhibited normal levels of tone-dependent learning. In addition, social interaction scores in both Tg lines were reduced in an isolation-induced resident-intruder test. There were also phenotypic increases in a GABAergic marker (parvalbumin) as well as in myelination markers (myelin basic protein and 2',3'-cyclic nucleotide 3'-phosphodiesterase) in their frontal cortex, indicating the authenticity of NRG1 hyper-signaling, although there were marked decreases in tyrosine hydroxylase levels and dopamine content in the hippocampus. CONCLUSIONS: These findings suggest that aberrant hyper-signals of NRG1 also disrupt various cognitive and behavioral processes. Thus, neuropathological implication of hyper NRG1 signaling in psychiatric diseases should be evaluated with further experimentation
Nonlinear Optical Response in two-dimensional Mott Insulators
We study the third-order nonlinear optical susceptibility and
photoexcited states of two-dimensional (2D) Mott insulators by using an
effective model in the strong-coupling limit of a half-filled Hubbard model. In
the numerically exact diagonalization calculations on finite-size clusters, we
find that the coupling of charge and spin degrees of freedom plays a crucial
role in the distribution of the dipole-allowed states with odd parity and the
dipole-forbidden states with even parity in the photoexcited states. This is in
contrast with the photoexcited states in one dimension, where the charge and
spin degrees of freedom are decoupled. In the third-harmonic generation (THG)
spectrum, main contribution is found to come from the process of three-photon
resonance associated with the odd-parity states. As a result, the two-photon
resonance process is less pronounced in the THG spectrum. The calculated THG
spectrum is compared with recent experimental data. We also find that
with cross-polarized configuration of pump and probe photons shows
spectral distributions similar to with co-polarized configuration,
although the weight is small. These findings will help the analyses of the
experimental data of in the 2D Mott insulators.Comment: 9 pages,5 figures,RevTeX
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