3,081 research outputs found
Evidence for Nodal superconductivity in SrScFePO
Point contact Andreev reflection spectra have been taken as a function of
temperature and magnetic field on the polycrystalline form of the newly
discovered iron-based superconductor Sr2ScFePO3. A zero bias conductance peak
which disappears at the superconducting transition temperature, dominates all
of the spectra. Data taken in high magnetic fields show that this feature
survives until 7T at 2K and a flattening of the feature is observed in some
contacts. Here we inspect whether these observations can be interpreted within
a d-wave, or nodal order parameter framework which would be consistent with the
recent theoretical model where the height of the P in the Fe-P-Fe plane is key
to the symmetry of the superconductivity. However, in polycrystalline samples
care must be taken when examining Andreev spectra to eliminate or take into
account artefacts associated with the possible effects of Josephson junctions
and random alignment of grains.Comment: Published versio
High Accretion Rate during Class 0 Phase due to External Trigger
Recent observations indicate that some class 0 sources have orders of
magnitude higher accretion rates than those of class I. We investigated the
conditions for the high accretion rates of some class 0 sources by numerical
calculations, modelling an external trigger. For no external trigger, we find
that the maximum value of the accretion rate is determined by the ratio
of the gravitational energy to the thermal one within a flat inner
region of the cloud core. The accretion rate reaches \sim 10^{-4} M_{\sun}
yr^{-1} if the cloud core has . For an external trigger we find
that the maximum value of the accretion rate is proportional to the momentum
given to the cloud core. The accretion rate reaches > 10^{-4} M_{\sun}
yr^{-1} with a momentum of \sim 0.1 M_{\sun} km s^{-1} when the initial
central density of the cloud core is . A comparison
between recent observational results for prestellar cores and our no triggered
collapse model indicates that the flat inner regions of typical prestellar
cores are not large enough to cause accretion rates of \sim 10^{-4} M_{\sun}
yr^{-1}. Our results show that the triggered collapse of the cloud core is
more preferable for the origin of the high accretion rates of class 0 sources
than no triggered collapse.Comment: 7 pages, 8 figures, accepted for publication in MNRA
Evolution of superconductivity by oxygen annealing in FeTe0.8S0.2
Oxygen annealing dramatically improved the superconducting properties of
solid-state-reacted FeTe0.8S0.2, which showed only a broad onset of
superconducting transition just after the synthesis. The zero resistivity
appeared and reached 8.5 K by the oxygen annealing at 200\degree C. The
superconducting volume fraction was also enhanced from 0 to almost 100%. The
lattice constants were compressed by the oxygen annealing, indicating that the
evolution of bulk superconductivity in FeTe0.8S0.2 was correlated to the
shrinkage of lattice.Comment: 13 pages, 6 figure
TGFBR2 and BAX Mononucleotide Tract Mutations, Microsatellite Instability, and Prognosis in 1072 Colorectal Cancers
Mononucleotide tracts in the coding regions of the TGFBR2 and BAX genes are commonly mutated in microsatellite instability-high (MSI-high) colon cancers. The receptor TGFBR2 plays an important role in the TGFB1 (transforming growth factor-Ξ², TGF-Ξ²) signaling pathway, and BAX plays a key role in apoptosis. However, a role of TGFBR2 or BAX mononucleotide mutation in colorectal cancer as a prognostic biomarker remains uncertain.We utilized a database of 1072 rectal and colon cancers in two prospective cohort studies (the Nurses' Health Study and the Health Professionals Follow-up Study). Cox proportional hazards model was used to compute mortality hazard ratio (HR), adjusted for clinical, pathological and molecular features including the CpG island methylator phenotype (CIMP), LINE-1 methylation, and KRAS, BRAF and PIK3CA mutations. MSI-high was observed in 15% (162/1072) of all colorectal cancers. TGFBR2 and BAX mononucleotide mutations were detected in 74% (117/159) and 30% (48/158) of MSI-high tumors, respectively. In Kaplan-Meier analysis as well as univariate and multivariate Cox regression analyses, compared to microsatellite stable (MSS)/MSI-low cases, MSI-high cases were associated with superior colorectal cancer-specific survival [adjusted HR, 0.34; 95% confidence interval (CI), 0.20-0.57] regardless of TGFBR2 or BAX mutation status. Among MSI-high tumors, TGFBR2 mononucleotide mutation was associated with CIMP-high independent of other variables [multivariate odds ratio, 3.57; 95% CI, 1.66-7.66; pβ=β0.0011].TGFBR2 or BAX mononucleotide mutations are not associated with the patient survival outcome in MSI-high colorectal cancer. Our data do not support those mutations as prognostic biomarkers (beyond MSI) in colorectal carcinoma
Collapse of Rotating Magnetized Molecular Cloud Cores and Mass Outflows
Collapse of the rotating magnetized molecular cloud core is studied with the
axisymmetric magnetohydrodynamical (MHD) simulations. Due to the change of the
equation of state of the interstellar gas, the molecular cloud cores experience
several different phases as collapse proce eds. In the isothermal run-away
collapse (), a pseudo-disk is formed and
it continues to contract till the opaque core is fo rmed at the center. In this
disk, a number of MHD fast and slow shock pairs appear running parallelly to
the disk. After the equation of state becomes hard, an adiabatic core is
formed, which is separated from the isothermal contracting pseudo-disk by the
accretion shock front facing radially outwards. By the effect of the magnetic
tension, the angular momentum is transferred from the disk mid-plane to the
surface. The gas with excess angular momentum near the surface is finally
ejected, which explains the molecular bipolar outflow. Two types of outflows
are observed. When the poloidal magnetic field is strong (magnetic energy is
comparable to the thermal one), a U-shaped outflow is formed in which fast
moving gas is confined to the wall whose shape looks like a capit al letter U.
The other is the turbulent outflow in which magnetic field lines and velocity
fi elds are randomly oriented. In this case, turbulent gas moves out almost
perpendicularly from the disk. The continuous mass accretion leads to the
quasistatic contraction of the first core. A second collapse due to
dissociation of H in the first core follows. Finally another quasistatic
core is again formed by atomic hydrogen (the second core). It is found that
another outflow is ejected around the second atomic core, which seems to
correspond to the optical jets or the fast neutral winds.Comment: submitted to Ap
Central administration of L- and D-aspartate attenuates stress behaviors by social isolation and CRF in neonatal chicks (Check Similarity)
Comparison of centrally injected tryptophan-related substances inducing sedation in acute isolation stress-induced neonatal chicks
First-principles Electronic Structure of Superconductor CaAlOFeP: Comparison with LaFePO and CaAlOFeAs
We investigate the electronic structures of iron-based superconductors having
perovskite-like blocking layers, %CaAlOFe(AsP)
from first principles. CaAlOFeP and
CaAlOFeAs from first principles.
CaAlOFeP is found to have two hole-like Fermi surfaces
around , and one hole-like Fermi surface around M in the unfolded
Brillouin zone. This is in contrast with LaFePO, where no Fermi surface is
found around M. The relationship of their band structures and measured
transition temperatures of superconductivity is discussed. The number of Fermi
surfaces in CaAlOFeP is also different from that of
CaAlOFeAs, in which only one Fermi surface is formed around
. Analysis using maximally localized Wannier functions clarifies that
the differences between their band structures originate mainly from the
pnictogen height. We then analyze the alloying effect on the electronic
structure of CaAlOFeAsP. It is found that its electronic
structure is similar to that of CaAlOFeP and
CaAlOFeAs with the average crystal structure, though
CaAlOFeAsP contains the pnictogen height disorder. We calculate
the generalized susceptibility for CaAlOFe(AsP)
and clarify the factors determining its tendency.Comment: 5 figures, to be published in J. Phys. Soc. Jp
The Optical System for the Large Size Telescope of the Cherenkov Telescope Array
The Large Size Telescope (LST) of the Cherenkov Telescope Array (CTA) is
designed to achieve a threshold energy of 20 GeV. The LST optics is composed of
one parabolic primary mirror 23 m in diameter and 28 m focal length. The
reflector dish is segmented in 198 hexagonal, 1.51 m flat to flat mirrors. The
total effective reflective area, taking into account the shadow of the
mechanical structure, is about 368 m. The mirrors have a sandwich structure
consisting of a glass sheet of 2.7 mm thickness, aluminum honeycomb of 60 mm
thickness, and another glass sheet on the rear, and have a total weight about
47 kg. The mirror surface is produced using a sputtering deposition technique
to apply a 5-layer coating, and the mirrors reach a reflectivity of 94%
at peak. The mirror facets are actively aligned during operations by an active
mirror control system, using actuators, CMOS cameras and a reference laser.
Each mirror facet carries a CMOS camera, which measures the position of the
light spot of the optical axis reference laser on the target of the telescope
camera. The two actuators and the universal joint of each mirror facet are
respectively fixed to three neighboring joints of the dish space frame, via
specially designed interface plate.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
Doping Dependence of Anisotropic Resistivities in Trilayered Superconductor Bi2Sr2Ca2Cu3O10+delta (Bi-2223)
The doping dependence of the themopower, in-plane resistivity rho_ab(T),
out-of-plane resistivity rho_c(T), and susceptibility has been systematically
measured for high-quality single crystal Bi2Sr2Ca2Cu3O10+delta. We found that
the transition temperature Tc and pseudogap formation temperature T_rho_c*,
below which rho_c shows a typical upturn, do not change from their optimum
values in the "overdoped" region, even though doping actually proceeds. This
suggests that, in overdoped region, the bulk is determined by the always
underdoped inner plane, which have a large superconducting gap, while the
carriers are mostly doped in the outer planes, which have a large phase
stiffness.Comment: 5 pages, 4 figures. to be published in PR
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