3,906 research outputs found
The interaction of amyloid A beta(1-40) with lipid bilayers and ganglioside as studied by P-31 solid-state NMR
Amyloid P-peptide (A beta) is a major component of plaques in Alzheimer's disease, and formation of senile plaques has been suggested to originate fro m regions of neuronal membrane rich in gangliosides. We analyzed the mode of interaction of A beta with lipid bilayers by multinuclear NMR using P-31 nuclei. We found that A beta (1-40) strongly perturbed the bilayer structure of dimyristoylphosphatidylcholine (DMPQ, to form a non-lamellar phase (most likely micellar). The ganglioside GM1 potentiated the effect of A beta (1-40), as viewed from P-31 NMR. The difference of the isotropic peak intensity between DMPC/A beta and DMPC/GM1/A beta suggests a specific interaction between A beta and GM1. We show that in the DMPC/GM1/A beta system there are three lipid phases, namely a lamellar phase, a hexagonal phase and non-oriented lipids. The latter two phases are induced by the presence of the A beta peptide, and facilitated by GM1. 9) 2008 Elsevier Ireland Ltd. All rights reserved
Constraints on the mass of a habitable planet with water of nebular origin
From an astrobiological point of view, special attention has been paid to the
probability of habitable planets in extrasolar systems. The purpose of this
study is to constrain a possible range of the mass of a terrestrial planet that
can get water. We focus on the process of water production through oxidation of
the atmospheric hydrogen--the nebular gas having been attracted
gravitationally--by oxide available at the planetary surface. For the water
production to work well on a planet, a sufficient amount of hydrogen and enough
high temperature to melt the planetary surface are needed. We have simulated
the structure of the atmosphere that connects with the protoplanetary nebula
for wide ranges of heat flux, opacity, and density of the nebular gas. We have
found both requirements are fulfilled for an Earth-mass planet for wide ranges
of the parameters. We have also found the surface temperature of planets of <=
0.3 Earth masses is lower than the melting temperature of silicate (~ 1500K).
On the other hand, a planet of more than several Earth masses becomes a gas
giant planet through runaway accretion of the nebular gas.Comment: 25 pages, 8 figures, to appear in the 01 September 2006 issue of Ap
Metallicity of the Fossil Group NGC 1550 Observed with Suzaku
We studied the temperature and metal abundance distributions of the
intra-cluster medium (ICM) in a group of galaxies NGC 1550 observed with
Suzaku. The NGC 1550 is classified as a fossil group, which have few bright
member galaxies except for the central galaxy. Thus, such a type of galaxy is
important to investigate how the metals are enriched to the ICM. With the
Suzaku XIS instruments, we directly measured not only Si, S, and Fe lines but
also O and Mg lines and obtained those abundances to an outer region of ~0.5
r_180 for the first time, and confirmed that the metals in the ICM of such a
fossil group are indeed extending to a large radius. We found steeper gradients
for Mg, Si, S, and Fe abundances, while O showed almost flat abundance
distribution. Abundance ratios of alpha-elements to Fe were similar to those of
the other groups and poor clusters. We calculated the number ratio of type II
to type Ia supernovae for the ICM enrichment to be 2.9 +- 0.5 within 0.1 r_180,
and the value was consistent with those for the other groups and poor clusters
observed with Suzaku. We also calculated metal mass-to-light ratios (MLRs) for
Fe, O and Mg with B-band and K-band luminosities of the member galaxies of NGC
1550. The derived MLRs were comparable to those of NGC 5044 group in the r<0.1
r_180 region, while those of NGC 1550 are slightly higher than those of NGC
5044 in the outer region.Comment: 11 pages, 7 figures, accepted for publication in PAS
Detection of Excess Hard X-ray Emission from the Group of Galaxies HCG62
From the group of galaxies HCG62, we detected an excess hard X-ray emission
in energies above keV with \A SCA. The excess emission is spatially
extended up to from the group center, and somewhat enhanced toward
north. Its spectrum can be represented by either a power-law of photon index
0.8-2.7, or a Bremsstrahlung of temperature keV. In the 2-10 keV range,
the observed hard X-ray flux, erg cm
s, implies a luminosity of erg s for a
Hubble constant of 50 km s Mpc. The emission is thus too luminous
to be attributed to X-ray binaries in the memb er galaxies. We discuss possible
origin of the hard X-ray emission.Comment: 6 pages, 3 Postscript figures, uses emulateapj.sty. Accepted for
publication in the Astrophysical Journal Letter
Automatic Computation of Cross Sections in HEP
For the study of reactions in High Energy Physics (HEP) automatic computation
systems have been developed and are widely used nowadays. GRACE is one of such
systems and it has achieved much success in analyzing experimental data. Since
we deal with the cross section whose value can be given by calculating hundreds
of Feynman diagrams, we manage the large scale calculation, so that effective
symbolic manipulation, the treat of singularity in the numerical integration
are required. The talk will describe the software design of GRACE system and
computational techniques in the GRACE.Comment: 6 pages, Latex, ICCP
Late-onset benefit in progressive advanced hepatocellular carcinoma with continued sorafenib therapy: a case report
<p>Abstract</p> <p>Introduction</p> <p>In the past, no effective systemic therapy has existed for patients with advanced hepatocellular carcinoma. Sorafenib, an oral multikinase inhibitor, has recently been shown to improve overall survival in patients with advanced hepatocellular carcinoma in two randomized, double-blinded, placebo-controlled trials. This drug has been approved as the first-line therapy for advanced hepatocellular carcinoma patients. We report an intriguing case of advanced hepatocellular carcinoma in which the patient achieved late- onset partial response by prolonged administration of sorafenib in spite of progressive disease.</p> <p>Case presentation</p> <p>A 54-year-old Japanese man was treated with sorafenib for multiple lung metastases after surgical resection for advanced hepatocellular carcinoma accompanied by vascular invasion of the left branch of the portal vein. Although the effective diagnosis was progressive disease, almost all sites began to reduce or disappear eight months after the diagnosis of progressive disease. A dramatic reduction in alpha-fetoprotein and des-gamma-carboxy prothrombin levels was observed. The patient finally achieved partial response and his status remains unchanged.</p> <p>Conclusions</p> <p>If tolerated, prolonged sorafenib treatment may be beneficial.</p
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