342 research outputs found
Application of two-parameter dynamical replica theory to retrieval dynamics of associative memory with non-monotonic neurons
The two-parameter dynamical replica theory (2-DRT) is applied to investigate
retrieval properties of non-monotonic associative memory, a model which lacks
thermodynamic potential functions. 2-DRT reproduces dynamical properties of the
model quite well, including the capacity and basin of attraction.
Superretrieval state is also discussed in the framework of 2-DRT. The local
stability condition of the superretrieval state is given, which provides a
better estimate of the region in which superretrieval is observed
experimentally than the self-consistent signal-to-noise analysis (SCSNA) does.Comment: 16 pages, 19 postscript figure
Transient dynamics for sequence processing neural networks
An exact solution of the transient dynamics for a sequential associative
memory model is discussed through both the path-integral method and the
statistical neurodynamics. Although the path-integral method has the ability to
give an exact solution of the transient dynamics, only stationary properties
have been discussed for the sequential associative memory. We have succeeded in
deriving an exact macroscopic description of the transient dynamics by
analyzing the correlation of crosstalk noise. Surprisingly, the order parameter
equations of this exact solution are completely equivalent to those of the
statistical neurodynamics, which is an approximation theory that assumes
crosstalk noise to obey the Gaussian distribution. In order to examine our
theoretical findings, we numerically obtain cumulants of the crosstalk noise.
We verify that the third- and fourth-order cumulants are equal to zero, and
that the crosstalk noise is normally distributed even in the non-retrieval
case. We show that the results obtained by our theory agree with those obtained
by computer simulations. We have also found that the macroscopic unstable state
completely coincides with the separatrix.Comment: 21 pages, 4 figure
Future changes in tropical cyclone activity in the North Indian Ocean projected by high-resolution MRI-AGCMs
Open Access at publisher's web site: http://www.springerlink.com/content/b682734237171631
Role of Ca2+ in the rapid cooling-induced Ca2+ release from sarcoplasmic reticulum in ferret cardiac muscles
Rapid lowering of the solution temperature (rapid cooling, RC) from 24 to 3°C within 3 s releases considerable amounts of Ca2+ from the sarcoplasmic reticulum (SR) in mammalian cardiac muscles. In this study, we investigated the intracellular mechanism of RC-induced Ca2+ release, especially the role of Ca2+, in ferret ventricular muscle. Saponin-treated skinned trabeculae were placed in a glass capillary, and the amount of Ca2+ released from the SR by RC and caffeine (50 mM) was measured with fluo-3. It was estimated that in the presence of ATP about 45% of the Ca2+ content in the SR was released by RC. The amount of SR Ca2+ released by RC was unchanged by the replacement of ATP by AMP-PCP (a non-hydrolysable ATP analogue and agonist for the ryanodine receptor but not for the Ca2+ pump of SR), suggesting that the suppression of the Ca2+ pump of SR at low temperature might not be a major mechanism in RC-induced Ca2+ release. The free Ca2+ concentration of the solution used for triggering RC-induced Ca2+ release was estimated to be only about 20 nM with fluo-3 or aequorin. When this solution was applied to the preparation at 3°C, only a small amount of Ca2+ was released from SR presumably by the Ca2+-induced Ca2+ release (CICR) mechanism. Thus, in mammalian cardiac muscles, RC releases a part of the (<50%) stored Ca2+ contained in the SR, and the mechanism of RC-induced Ca2+ release may differ from that of CICR, which is thought to play a role in frog skeletal muscle fibres that express ryanodine receptors of different types
A massive quiescent galaxy in a group environment at
We report on the spectroscopic confirmation of a massive quiescent galaxy at
in the COSMOS field with Keck/MOSFIRE. The object was
first identified as a galaxy with suppressed star formation at
from the COSMOS2020 catalog. The follow-up
spectroscopy with MOSFIRE in the -band reveals a faint [OII] emission and
the Balmer break, indicative of evolved stellar populations. We perform the
spectral energy distribution fitting using both the photometry and spectrum to
infer physical properties. The obtained stellar mass is high () and the current star formation rate is more than 1 dex
below that of main-sequence galaxies at . Its star formation history
suggests that this galaxy experienced starburst at followed by a rapid
quenching phase. This is one of the youngest quiescent galaxies at and is
likely a galaxy in the process of being quenched. An unique aspect of the
galaxy is that it is in an extremely dense region; there are four massive
star-forming galaxies at located within 150 physical
kpc from the galaxy. Interestingly, three of them have strongly overlapping
virial radii with that of the central quiescent galaxy (), suggesting that the over-density region is likely the
highest redshift candidate of a dense group with a spectroscopically confirmed
quiescent galaxy at the center. The group provides us with an unique
opportunity to gain insights into the role of the group environment for
quenching at 4 - 5 corresponding to the formation epoch of massive
elliptical galaxies in the local Universe.Comment: 13 pages, 7 figures, 2 tables; submitted to Ap
First Data Release of the Hyper Suprime-Cam Subaru Strategic Program
The Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) is a three-layered
imaging survey aimed at addressing some of the most outstanding questions in
astronomy today, including the nature of dark matter and dark energy. The
survey has been awarded 300 nights of observing time at the Subaru Telescope
and it started in March 2014. This paper presents the first public data release
of HSC-SSP. This release includes data taken in the first 1.7 years of
observations (61.5 nights) and each of the Wide, Deep, and UltraDeep layers
covers about 108, 26, and 4 square degrees down to depths of i~26.4, ~26.5, and
~27.0 mag, respectively (5sigma for point sources). All the layers are observed
in five broad bands (grizy), and the Deep and UltraDeep layers are observed in
narrow bands as well. We achieve an impressive image quality of 0.6 arcsec in
the i-band in the Wide layer. We show that we achieve 1-2 per cent PSF
photometry (rms) both internally and externally (against Pan-STARRS1), and ~10
mas and 40 mas internal and external astrometric accuracy, respectively. Both
the calibrated images and catalogs are made available to the community through
dedicated user interfaces and database servers. In addition to the pipeline
products, we also provide value-added products such as photometric redshifts
and a collection of public spectroscopic redshifts. Detailed descriptions of
all the data can be found online. The data release website is
https://hsc-release.mtk.nao.ac.jp/.Comment: 34 pages, 20 figures, 7 tables, moderate revision, accepted for
publication in PAS
Size - Stellar Mass Relation and Morphology of Quiescent Galaxies at in Public Fields
We present the results of a systematic study of the rest-frame optical
morphology of quiescent galaxies at using the Near-Infrared Camera
(NIRCam) onboard . Based on a sample selected by color or
color, we focus on 26 quiescent galaxies with
at with publicly
available data. Their sizes are constrained by fitting the S\'ersic
profile to all available NIRCam images. We see a negative correlation between
the observed wavelength and the size in our sample and derive their size at the
rest-frame taking into account this trend. Our quiescent
galaxies show a significant correlation between the rest-frame size and the stellar mass at . The analytical fit for them at
implies that our size - stellar mass relations
are below those at lower redshifts, with the amplitude of
at . This value agrees with the
extrapolation from the size evolution of quiescent galaxies at in the
literature, implying that the size of quiescent galaxies increases
monotonically from . Our sample is mainly composed of galaxies with
bulge-like structures according to their median S\'ersic index and axis ratio
of and , respectively. On the other hand, there is a
trend of increasing fraction of galaxies with low S\'ersic index, suggesting
might be the epoch of onset of morphological transformation with a
fraction of very notable disky quenched galaxies.Comment: 23 pages, 16 figures, 2 tables; submitted to Ap
Study of fission using multi-nucleon transfer reactions
Multi-nucleon transfer channels of the reactions of 18O+232Th, 18O+238U, 18O+248Cm were used to measure fission-fragment mass distribution for various nuclides and their excitation energy dependence. Predominantly asymmetric fission is observed at low excitation energies for all the studied cases, with an increase of the symmetric fission towards high excitation energies. Experimental data are compared with predictions of the fluctuation-dissipation model, where effects of multi-chance fission (neutron evaporation prior to fission) was introduced. It was shown that a reliable understanding of the observed fission fragment mass distributions can be obtained only invoking multi-chance fissions
Background: Tokyo Guidelines for the management of acute cholangitis and cholecystitis
There are no evidence-based-criteria for the diagnosis, severity assessment, of treatment of acute cholecysitis or acute cholangitis. For example, the full complement of symptoms and signs described as Charcot’s triad and as Reynolds’ pentad are infrequent and as such do not really assist the clinician with planning management strategies. In view of these factors, we launched a project to prepare evidence-based guidelines for the management of acute cholangitis and cholecystitis that will be useful in the clinical setting. This research has been funded by the Japanese Ministry of Health, Labour, and Welfare, in cooperation with the Japanese Society for Abdominal Emergency Medicine, the Japan Biliary Association, and the Japanese Society of Hepato-Biliary-Pancreatic Surgery. A working group, consisting of 46 experts in gastroenterology, surgery, internal medicine, emergency medicine, intensive care, and clinical epidemiology, analyzed and examined the literature on patients with cholangitis and cholecystitis in order to produce evidence-based guidelines. During the investigations we found that there was a lack of high-level evidence, for treatments, and the working group formulated the guidelines by obtaining consensus, based on evidence categorized by level, according to the Oxford Centre for Evidence-Based Medicine Levels of Evidence of May 2001 (version 1). This work required more than 20 meetings to obtain a consensus on each item from the working group. Then four forums were held to permit examination of the Guideline details in Japan, both by an external assessment committee and by the working group participants (version 2). As we knew that the diagnosis and management of acute biliary infection may differ from country to country, we appointed a publication committee and held 12 meetings to prepare draft Guidelines in English (version 3). We then had several discussions on these draft guidelines with leading experts in the field throughout the world, via e-mail, leading to version 4. Finally, an International Consensus Meeting took place in Tokyo, on 1–2 April, 2006, to obtain international agreement on diagnostic criteria, severity assessment, and management
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