315 research outputs found
Characteristics of cosmic ray pole-equator anisotropy derived from spherical harmonic analysis of neutron monitor data
The spherical harmonic analysis of cosmic ray neutron data from the worldwide network neutron monitor stations during the years, 1966 to 1969 was carried out. The second zonal harmonic component obtained from the analysis corresponds to the Pole-Equator anisotropy of the cosmic ray neutron intensity. Such an anisotropy makes a semiannual variation. In addition to this, it is shown that the Pole-Equator anisotropy makes a variation depending on the interplanetary magnetic field (IMF) sector polarities around the passages of the IMF sector boundary. A mechanism to interpret these results is also discussed
Structural parts involved in activation and inactivation of the sodium channel.
Structure–function relationships of the sodium channel expressed inXenopus oocytes have been investigated by the combined use of site–directed mutagenesis and patch-clamp recording. This study provides evidence that the positive charges in segment S4 are involved in the voltage–sensing mechanism for activation of the channel and that the region between repeats III and IV is important for its inactivation
Dark energy constraints and correlations with systematics from CFHTLS weak lensing, SNLS supernovae Ia and WMAP5
We combine measurements of weak gravitational lensing from the CFHTLS-Wide
survey, supernovae Ia from CFHT SNLS and CMB anisotropies from WMAP5 to obtain
joint constraints on cosmological parameters, in particular, the dark energy
equation of state parameter w. We assess the influence of systematics in the
data on the results and look for possible correlations with cosmological
parameters.
We implement an MCMC algorithm to sample the parameter space of a flat CDM
model with a dark-energy component of constant w. Systematics in the data are
parametrised and included in the analysis. We determine the influence of
photometric calibration of SNIa data on cosmological results by calculating the
response of the distance modulus to photometric zero-point variations. The weak
lensing data set is tested for anomalous field-to-field variations and a
systematic shape measurement bias for high-z galaxies.
Ignoring photometric uncertainties for SNLS biases cosmological parameters by
at most 20% of the statistical errors, using supernovae only; the parameter
uncertainties are underestimated by 10%. The weak lensing field-to-field
variance pointings is 5%-15% higher than that predicted from N-body
simulations. We find no bias of the lensing signal at high redshift, within the
framework of a simple model. Assuming a systematic underestimation of the
lensing signal at high redshift, the normalisation sigma_8 increases by up to
8%. Combining all three probes we obtain -0.10<1+w<0.06 at 68% confidence
(-0.18<1+w<0.12 at 95%), including systematic errors. Systematics in the data
increase the error bars by up to 35%; the best-fit values change by less than
0.15sigma. [Abridged]Comment: 14 pages, 10 figures. Revised version, matches the one to be
published in A&A. Modifications have been made corresponding to the referee's
suggestions, including reordering of some section
An autopsy report on multiple system atrophy diagnosed immunohistochemically despite severe ischaemic damage: a new approach for investigation of medical practice associated deaths in Japan
A 60-year old man with a 10-year history of multiple system atrophy (MSA) was found in respiratory arrest. After 4 months of respiratory support with two episodes of septic shock, he died. Autopsy disclosed severe atrophy of the mesencephalon, brainstem, medulla oblongata and cerebellum. Gallyas–Braak, α-synuclein and ubiquitin-positive inclusions in the cytoplasm of glial cells were evident, despite the severe ischaemic damage due to respiratory arrest and subsequent respiratory support for 4 months. The cause of respiratory arrest was not identified, but could be explained by the natural history of MSA. The bereaved family, who had suspected malpractice, was satisfied with the explanation based on the investigation performed by eight expert doctors, one expert nurse, two coordinator nurses and two lawyers in the model project promoted by the Japanese government
Numerical Galaxy Catalog -I. A Semi-analytic Model of Galaxy Formation with N-body simulations
We construct the Numerical Galaxy Catalog (GC), based on a semi-analytic
model of galaxy formation combined with high-resolution N-body simulations in a
-dominated flat cold dark matter (CDM) cosmological model.
The model includes several essential ingredients for galaxy formation, such as
merging histories of dark halos directly taken from N-body simulations,
radiative gas cooling, star formation, heating by supernova explosions
(supernova feedback), mergers of galaxies, population synthesis, and extinction
by internal dust and intervening HI clouds. As the first paper in a series
using this model, we focus on basic photometric, structural and kinematical
properties of galaxies at present and high redshifts. Two sets of model
parameters are examined, strong and weak supernova feedback models, which are
in good agreement with observational luminosity functions of local galaxies in
a range of observational uncertainty. Both models agree well with many
observations such as cold gas mass-to-stellar luminosity ratios of spiral
galaxies, HI mass functions, galaxy sizes, faint galaxy number counts and
photometric redshift distributions in optical pass-bands, isophotal angular
sizes, and cosmic star formation rates. In particular, the strong supernova
feedback model is in much better agreement with near-infrared (K'-band) faint
galaxy number counts and redshift distribution than the weak feedback model and
our previous semi-analytic models based on the extended Press-Schechter
formalism. (Abridged)Comment: 26 pages including 27 figures, accepted for publication in ApJ,
full-resolution version is available at
http://grape.astron.s.u-tokyo.ac.jp/~yahagi/nugc
Transformation Pathways of Silica under High Pressure
Concurrent molecular dynamics simulations and ab initio calculations show
that densification of silica under pressure follows a ubiquitous two-stage
mechanism. First, anions form a close-packed sub-lattice, governed by the
strong repulsion between them. Next, cations redistribute onto the interstices.
In cristobalite silica, the first stage is manifest by the formation of a
metastable phase, which was observed experimentally a decade ago, but never
indexed due to ambiguous diffraction patterns. Our simulations conclusively
reveal its structure and its role in the densification of silica.Comment: 14 pages, 4 figure
Usefulness and safety of 0.4% sodium hyaluronate solution as a submucosal fluid "cushion" for endoscopic resection of colorectal mucosal neoplasms: A prospective multi-center open-label trial
<p>Abstract</p> <p>Background</p> <p>Sodium hyaluronate (SH) solution has been used for submucosal injection in endoscopic resection to create a long-lasting submucosal fluid "cushion". Recently, we proved the usefulness and safety of 0.4% SH solution in endoscopic resection for gastric mucosal tumors. To evaluate the usefulness of 0.4% SH as a submucosal injection solution for colorectal endoscopic resection, we conducted an open-label clinical trial on six referral hospitals in Japan.</p> <p>Methods</p> <p>A prospective multi-center open-label study was designed. A total of 41 patients with 5–20 mm neoplastic lesions localized in the colorectal mucosa at six referral hospitals in Japan in a single year period from December 2002 to November 2003 were enrolled and underwent endoscopic resection with SH. The usefulness of 0.4% SH was assessed by the <it>en bloc </it>complete resection and the formation and maintenance of mucosal lesion-lifting during endoscopic resection. Safety was evaluated by analyzing adverse events during the study period.</p> <p>Results</p> <p>The usefulness rate was high (82.5%; 33/40). The following secondary outcome measures were noted: 1) steepness of mucosal lesion-lifting, 75.0% (30/40); 2) intraoperative complications, 10.0% (4/40); 3) time required for mucosal resection, 6.7 min; 4) volume of submucosal injection, 6.8 mL and 5) ease of mucosal resection, 87.5% (35/40). Two adverse events of bleeding potentially related to 0.4% SH were reported.</p> <p>Conclusion</p> <p>Using 0.4% SH solution enabled sufficient lifting of a colorectal intramucosal lesion during endoscopic resection, reducing the need for additional injections and the risk of perforation. Therefore, 0.4% SH may contribute to the reduction of complications and serve as a promising submucosal injection solution due to its potentially superior safety in comparison to normal saline solution.</p
VLT photometry in the Antlia Cluster: the giant ellipticals NGC 3258 and NGC 3268 and their globular cluster systems
We present a deep VLT photometry in the regions surrounding the two dominant
galaxies of the Antlia cluster, the giant ellipticals NGC 3258 and NGC 3268. We
construct the luminosity functions of their globular cluster systems (GCSs) and
determine their distances through the turn-over magnitudes. These distances are
in good agreement with those obtained by the SBF method. There is some, but not
conclusive, evidence that the distance to NGC 3268 is larger by several Mpc.
The GCSs colour distributions are bimodal but the brightest globular clusters
(GCs) show a unimodal distribution with an intermediate colour peak. The radial
distributions of both GCSs are well fitted by de Vaucouleurs laws up to 5
arcmin. Red GCs present a steeper radial density profile than the blue GCs, and
follow closely the galaxies' brightness profiles. Total GC populations are
estimated to be about 6000+/-150 GCs in NGC 3258 and 4750+/-150 GCs in NGC
3268. We discuss the possible existence of GCs in a field located between the
two giant galaxies (intracluster GCs). Their luminosity functions and number
densities are consistent with the two GCSs overlapping in projection.Comment: 13 pages, 16 figures. Accepted for publication in MNRA
Merger rates of dark matter haloes: a comparison between EPS and N-body results
We calculate merger rates of dark matter haloes using the Extended
Press-Schechter approximation (EPS) for the Spherical Collapse (SC) and the
Ellipsoidal Collapse (EC) models.
Merger rates have been calculated for masses in the range
to and for
redshifts in the range 0 to 3 and they have been compared with merger rates
that have been proposed by other authors as fits to the results of N-body
simulations. The detailed comparison presented here shows that the agreement
between the analytical models and N-body simulations depends crucially on the
mass of the descendant halo. For some range of masses and redshifts either SC
or EC models approximate satisfactory the results of N-body simulations but for
other cases both models are less satisfactory or even bad approximations. We
showed, by studying the parameters of the problem that a disagreement --if it
appears-- does not depend on the values of the parameters but on the kind of
the particular solution used for the distribution of progenitors or on the
nature of EPS methods.
Further studies could help to improve our understanding about the physical
processes during the formation of dark matter haloes.Comment: 29 pages, 9 figure
On the cosmological mass function theory
This paper provides, from one side, a review of the theory of the
cosmological mass function from a theoretical point of view, starting from the
seminal paper of Press & Shechter (1974) to the last developments (Del Popolo &
Gambera (1998, 1999), Sheth & Tormen 1999 (ST), Sheth, Mo & Tormen 2001 (ST1),
Jenkins et al. 2001 (J01), Shet & Tormen 2002 (ST2), Del Popolo 2002a, Yagi et
al. 2004 (YNY)), and from another side some improvements on the multiplicity
function models in literature. ...Comment: Astronomy Reports, in prin
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