8,533 research outputs found
Implementation of a webGIS service platform for high mountain climate research: the SHARE GeoNetwork project
The implementation of a webGIS service platform dedicated to the management and sharing of climatological data acquired by
high elevation stations is the core of the Station at High Altitude for Research on the Environment (SHARE) GeoNetwork project,
promoted by the Ev-K2 CNR Committee. The web platform basically will provide three types of services: structured metadata
archive, data and results from high-altitude environments research and projects; access to high-altitude Ev-K2 CNR stations and
creation of a network of existing stations; dedicated webGIS for geo-referenced data collected during the research. High elevation
environmental and territorial data and metadata are catalogued in a single integrated platform to get access to the information
heritage of the SHARE project, using open-source tools: Geonetwork for the metadata catalogue and webGIS resources, and the
open-source Weather and Water Database (WDB), developed by the Norwegian Meteorological Institute, for the database information
system implementation. The information system is designed to have a main node, with the possibility to install relocated
subsystems based on the same technology, named focal point of SHARE, which will contain metadata and data connected to the
main node. In this study, a new structure of metadata for the description of the climatological stations is proposed and WDB
adaptation and data preprocessing are described in detail, giving code and script samples
On the nature of the X-ray absorption in the Seyfert 2 galaxy NGC 4507
We present results of the ASCA observation of the Seyfert 2 galaxy NGC 4507.
The 0.5-10 keV spectrum is rather complex and consists of several components:
(1) a hard X-ray power law heavily absorbed by a column density of about 3
10^23 cm^-2, (2) a narrow Fe Kalpha line at 6.4 keV, (3) soft continuum
emission well above the extrapolation of the absorbed hard power law, (4) a
narrow emission line at about 0.9 keV. The line energy, consistent with highly
ionized Neon (NeIX), may indicate that the soft X-ray emission derives from a
combination of resonant scattering and fluorescence in a photoionized gas. Some
contribution to the soft X-ray spectrum from thermal emission, as a blend of Fe
L lines, by a starburst component in the host galaxy cannot be ruled out with
the present data.Comment: 8 pages, LateX, 5 figures (included). Uses mn.sty and epsfig.sty. To
appear in MNRA
Field-Effect Transistor on SrTiO3 with sputtered Al2O3 Gate Insulator
A field-effect transistor that employs a perovskite-type SrTiO3 single
crystal as the semiconducting channel is revealed to function as n-type
accumulation-mode device with characteristics similar to that of organic FET's.
The device was fabricated at room temperature by sputter-deposition of
amorphous Al2O3 films as a gate insulator on the SrTiO3 substrate. The
field-effect(FE) mobility is 0.1cm2/Vs and on-off ratio exceeds 100 at room
temperature. The temperature dependence of the FE mobility down to 2K shows a
thermal-activation-type behavior with an activation energy of 0.6eV
Merging particle filter for sequential data assimilation
A new filtering technique for sequential data assimilation, the merging particle filter (MPF), is proposed. The MPF is devised to avoid the degeneration problem, which is inevitable in the particle filter (PF), without prohibitive computational cost. In addition, it is applicable to cases in which a nonlinear relationship exists between a state and observed data where the application of the ensemble Kalman filter (EnKF) is not effectual. In the MPF, the filtering procedure is performed based on sampling of a forecast ensemble as in the PF. However, unlike the PF, each member of a filtered ensemble is generated by merging multiple samples from the forecast ensemble such that the mean and covariance of the filtered distribution are approximately preserved. This merging of multiple samples allows the degeneration problem to be avoided. In the present study, the newly proposed MPF technique is introduced, and its performance is demonstrated experimentally
Criticality versus q in the 2+1-dimensional clock model
Using Monte Carlo simulations we have studied the clock model in
two different representations, the phase-representation and the
loop/dumbbell-gas (LDG) representation. We find that for the critical
exponents and for the specific heat and the correlation length,
respectively, take on values corresponding to the case , where
model, i.e. in terms of critical properties
the limiting behaviour is reached already at .Comment: Minor corrections; journal ref adde
Hard X-ray Luminosities of Multinuclei Infrared Luminous Galaxies Showing a Radio/Far-Infrared Excess
We report the results of hard X-ray observations of four multinuclei merging
infrared luminous galaxies (IRLGs). We selected these four sources for their
excess of radio to far-infrared luminosity ratio compared with starburst
galaxies. This excess suggests that activity associated with a supermassive
black hole (SMBH) contributes strongly to the IRLGs' bolometric luminosities.
Although we expect strong hard X-ray emission from the SMBH-driven activity,
the radio-excess multinuclei merging IRLGs show considerably smaller hard X-ray
luminosities relative to far-infrared (40500 m) and infrared (81000
m) luminosities than active galactic nuclei (AGNs) showing a similar
radio-excess. This result may demonstrate that emission in the hard X-ray
region from SMBH-driven activity in the multinuclei merging IRLGs is severely
suppressed compared to a typical spectral energy distribution of SMBH-driven
activity in AGNs. If this is a common property of merging IRLGs, without its
correction, hard X-ray observations underestimate the contribution of
SMBH-driven activity to the bolometric luminosities of merging IRLGs.Comment: 25 pages of text, 4 figures, aaspp4.sty, Astrophysical Journal, in
press (1999, Volume 527
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