426 research outputs found
Hyperlink Management System and ID Converter System: enabling maintenance-free hyperlinks among major biological databases
Hyperlink Management System (HMS) is a system for automatically updating and maintaining hyperlinks among major public databases in the field of life science. We daily create corresponding tables of data IDs of major databases for human genes and proteins, and provide a CGI-program that returns correct and up-to-date URLs for showing data of various databases that correspond to user-specified IDs. The HMS can deal with various IDs: accession numbers of International Nucleotide Sequence Databases, HUGO Gene Symbols and IDs of UniProt, PDB, H-InvDB and others, and it can return URLs of various databases: H-InvDB, HUGO Gene Nomenclature Committee Database, NCBI Entrez Gene, UniProt, PDB and others. For example, 23 297 pages of Locus view of H-InvDB are reachable by using HUGO Gene Symbols through the HMS. Not only the CGI-program, the HMS provides a Web page for finding and opening URLs of these databases. Although hyperlinking is an effective way of relating biological data among different databases, updating hyperlinks has been a laborious work. The HMS fully automates the job, enabling maintenance-free hyperlinks. We also developed the ID Converter System (ICS) for simply converting data IDs by using corresponding tables in the HMS. The HMS and ICS are freely available at http://biodb.jp/
Flare Ribbons Observed with G-band and FeI 6302A Filters of the Solar Optical Telescope on Board Hinode
The Solar Optical Telescope (SOT) on board Hinode satellite observed an X3.4
class flare on 2006 December 13. Typical two-ribbon structure was observed, not
only in the chromospheric CaII H line but also in G-band and FeI 6302A line.
The high-resolution, seeing-free images achieved by SOT revealed, for the first
time, the sub-arcsec fine structures of the "white light" flare. The G-band
flare ribbons on sunspot umbrae showed a sharp leading edge followed by a
diffuse inside, as well as previously known core-halo structure. The underlying
structures such as umbral dots, penumbral filaments and granules were visible
in the flare ribbons. Assuming that the sharp leading edge was directly heated
by particle beam and the diffuse parts were heated by radiative back-warming,
we estimate the depth of the diffuse flare emission using the intensity profile
of the flare ribbon. We found that the depth of the diffuse emission is about
100 km or less from the height of the source of radiative back-warming. The
flare ribbons were also visible in the Stokes-V images of FeI 6302A, as a
transient polarity reversal. This is probably related to "magnetic transient"
reported in the literature. The intensity increase in Stokes-I images indicates
that the FeI 6302A line was significantly deformed by the flare, which may
cause such a magnetic transient.Comment: 14 pages, 7 figures, PASJ in pres
Comparative Analysis of Non-thermal Emissions and Study of Electron Transport in a Solar Flare
We study the non-thermal emissions in a solar flare occurring on 2003 May 29
by using RHESSI hard X-ray (HXR) and Nobeyama microwave observations. This
flare shows several typical behaviors of the HXR and microwave emissions: time
delay of microwave peaks relative to HXR peaks, loop-top microwave and
footpoint HXR sources, and a harder electron energy distribution inferred from
the microwave spectrum than from the HXR spectrum. In addition, we found that
the time profile of the spectral index of the higher-energy (\gsim 100 keV)
HXRs is similar to that of the microwaves, and is delayed from that of the
lower-energy (\lsim 100 keV) HXRs. We interpret these observations in terms
of an electron transport model called {\TPP}. We numerically solved the
spatially-homogeneous {\FP} equation to determine electron evolution in energy
and pitch-angle space. By comparing the behaviors of the HXR and microwave
emissions predicted by the model with the observations, we discuss the
pitch-angle distribution of the electrons injected into the flare site. We
found that the observed spectral variations can qualitatively be explained if
the injected electrons have a pitch-angle distribution concentrated
perpendicular to the magnetic field lines rather than isotropic distribution.Comment: 32 pages, 12 figures, accepted for publication in The Astronomical
Journa
Benefits of Artificially Generated Gravity Gradients for Interferometric Gravitational-Wave Detectors
We present an approach to experimentally evaluate gravity gradient noise, a
potentially limiting noise source in advanced interferometric gravitational
wave (GW) detectors. In addition, the method can be used to provide sub-percent
calibration in phase and amplitude of modern interferometric GW detectors.
Knowledge of calibration to such certainties shall enhance the scientific
output of the instruments in case of an eventual detection of GWs. The method
relies on a rotating symmetrical two-body mass, a Dynamic gravity Field
Generator (DFG). The placement of the DFG in the proximity of one of the
interferometer's suspended test masses generates a change in the local
gravitational field detectable with current interferometric GW detectors.Comment: 16 pages, 4 figure
Statistics of low-energy levels of a one-dimensional weakly localized Frenkel exciton: A numerical study
Numerical study of the one-dimensional Frenkel Hamiltonian with on-site
randomness is carried out. We focus on the statistics of the energy levels near
the lower exciton band edge, i. e. those determining optical response. We found
that the distribution of the energy spacing between the states that are well
localized at the same segment is characterized by non-zero mean, i.e. these
states undergo repulsion. This repulsion results in a local discrete energy
structure of a localized Frenkel exciton. On the contrary, the energy spacing
distribution for weakly overlapping local ground states (the states with no
nodes within their localization segments) that are localized at different
segments has zero mean and shows almost no repulsion. The typical width of the
latter distribution is of the same order as the typical spacing in the local
discrete energy structure, so that this local structure is hidden; it does not
reveal itself neither in the density of states nor in the linear absorption
spectra. However, this structure affects the two-exciton transitions involving
the states of the same segment and can be observed by the pump-probe
spectroscopy. We analyze also the disorder degree scaling of the first and
second momenta of the distributions.Comment: 10 pages, 6 figure
Magnetic Reconnection in Non-Equilibrium Ionization Plasma
We have studied the effect of time-dependent ionization and recombination
processes on magnetic reconnection in the solar corona. Petschek-type steady
reconnection, in which model the magnetic energy is mainly converted at the
slow-mode shocks, was assumed. We carried out the time-dependent ionization
calculation in the magnetic reconnection structure. We only calculated the
transient ionization of iron; the other species were assumed to be in
ionization equilibrium. The intensity of line emissions at specific wavelengths
were also calculated for comparison with {\it Hinode} or other observations in
future. What we found is as follows: (1) iron is mostly in non-equilibrium
ionization in the reconnection region, (2) the intensity of line emission
estimated by the time-dependent ionization calculation is significantly
different from that with the ionization equilibrium assumption, (3) the effect
of time-dependent ionization is sensitive to the electron density in the case
that the electron density is less than cm, (4) the effect of
thermal conduction lessens the time-dependent ionization effect, (5) the effect
of radiative cooling is negligibly small even if we take into account
time-dependent ionization.Comment: accepted for publication in The Astrophysical Journa
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Regional analysis of FDG and PIB-PET images in normal aging, mild cognitive impairment, and Alzheimer’s disease
Assessment of diffuse Lewy body disease by 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET)
BACKGROUND: Lewy body disease is, after Alzheimer's disease, the second most common cause of senile degenerative dementia with progressive cognitive deterioration, fluctuation of cognitive and motoric functions and psychotic symptoms. It is characterized histologically by the occurrence of Lewy bodies in allocortical, neocortical and subcortical structures. The aim of this study was to measure the cortical glucose metabolism using FDG PET (2-[18F]fluoro-2-deoxy-D-glucose position emission tomography) compared to normal subjects. PATIENTS AND METHODS: Five patients (5 m, mean age 75 y) with clinically suspected diffuse Lewy body disease (DLB) were studied with FDG PET. PET studies of the head were performed with a Siemens ECAT-ART PET-scanner with attenuation correction using 137-Cs point sources. RESULTS: We found the same distribution pattern of diffuse glucose hypometabolism in the entire cortical region with relative sparing of the primary sensory-motor cortex in all the patients. The few cases reported in the literature so far describe findings similar to ours. CONCLUSION: The pattern of diffuse glucose hypometabolism in the entire cortex including the occipital region seems to be a typical feature of DLB that is distinctive from dementia of Alzheimer's disease
Mechanisms underlying fatigue: a voxel-based morphometric study of chronic fatigue syndrome
BACKGROUND: Fatigue is a crucial sensation that triggers rest, yet its underlying neuronal mechanisms remain unclear. Intense long-term fatigue is a symptom of chronic fatigue syndrome, which is used as a model to study the mechanisms underlying fatigue. METHODS: Using magnetic resonance imaging, we conducted voxel-based morphometry of 16 patients and 49 age-matched healthy control subjects. RESULTS: We found that patients with chronic fatigue syndrome had reduced gray-matter volume in the bilateral prefrontal cortex. Within these areas, the volume reduction in the right prefrontal cortex paralleled the severity of the fatigue of the subjects. CONCLUSION: These results are consistent with previous reports of an abnormal distribution of acetyl-L-carnitine uptake, which is one of the biochemical markers of chronic fatigue syndrome, in the prefrontal cortex. Thus, the prefrontal cortex might be an important element of the neural system that regulates sensations of fatigue
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