1,021 research outputs found
Magnetic field resistant quantum interferences in bismuth nanowires based Josephson junctions
We investigate proximity induced superconductivity in micrometer-long bismuth
nanowires con- nected to superconducting electrodes with a high critical field.
At low temperature we measure a supercurrent that persists in magnetic fields
as high as the critical field of the electrodes (above 11 T). The critical
current is also strongly modulated by the magnetic field. In certain samples we
find regular, rapid SQUID-like periodic oscillations occurring up to high
fields. Other samples ex- hibit less periodic but full modulations of the
critical current on Tesla field scales, with field-caused extinctions of the
supercurrent. These findings indicate the existence of low dimensionally, phase
coherent, interfering conducting regions through the samples, with a subtle
interplay between orbital and spin contributions. We relate these surprising
results to the electronic properties of the surface states of bismuth, strong
Rashba spin-orbit coupling, large effective g factors, and their effect on the
induced superconducting correlations.Comment: 5 page
The Extended Bose Hubbard Model on the Two Dimensional Honeycomb Lattice
We study the extended Bose-Hubbard model on a two-dimensional honeycomb
lattice by using large scale quantum Monte Carlo simulations. We present the
ground state phase diagrams for both the hard-core case and the soft-core case.
For the hard-core case, the transition between solid and the
superfluid is first order and the supersolid state is unstable towards phase
separation. For the soft-core case, due to the presence of the multiple
occupation, a stable particle induced supersolid (SS-p) phase emerges when
. The transition from the solid at to the SS-p is second
order with the superfluid density scaling as . The
SS-p has the same diagonal order as the solid at . As the chemical
potential increasing further, the SS-p will turn into a solid where two bosons
occupying each site of a sublattice through a first order transition. We also
calculate the critical exponents of the transition between solid and
superfluid at the Heisenberg point for the hard core case. We find the
dynamical critical exponent , which is smaller than results obtained on
smaller lattices. This indicates that approaches zero in the
thermodynamic limit, so the transition is also first order even at the
Heisenberg point.Comment: 6pages, 6figure
Lipopolysaccharide-stimulated Leukocytes Contribute to Platelet Aggregative Dysfunction, Which is Attenuated by Catalase in Rats
Endotoxemia causes several hematological dysfunctions, including platelet degranulation or disseminated intravascular coagulation, which lead to thrombotic and hemorrhagic events. Here, we tested the hypothesis that bacterial lipopolysaccharide (LPS)-stimulated leukocytes contribute to platelet aggregative dysfunction, and this function is attenuated by antioxidants. Plateletrich plasma (PRP) was prepared from whole blood of normal and endotoxemic rats. The ability of platelet aggregation was measured by an aggregometer. LPS (50–100 μg/mL) was incubated with PRP, whole blood and PRP with polymorphonuclear leukocytes (PMNs) for 30 minutes, 60 minutes and 90 minutes, and platelet aggregation was detected. LPS-induced platelet aggregative dysfunction was undetectable in intact PRP which was isolated from normal whole blood, whereas it was detected in PRP isolated from endotoxemic rats and LPS-treated whole blood. Moreover, the effect of LPS-induced platelet aggregative dysfunction on intact PRP was observed when the PMNs were added. LPS-induced platelet aggregative dysfunction was significantly attenuated by catalase alone and in combination with NG-nitro-L-arginine methyl ester, but not by NG-nitro-L-arginine methyl ester alone. These results indicate that LPS-stimulated PMNs modulate platelet aggregation during LPS treatment and the effects are reversed by antioxidants. PMNs serve as an approach to understand LPS-induced platelet aggregative dysfunction during endotoxemia. During this process, the generation of reactive oxygen species, hydrogen peroxide especially, from LPS-stimulated PMNs could be an important potential factor in LPS-induced platelet aggregative dysfunction. Catalase contributes to the prevention of platelet dysfunction during LPS-induced sepsis
Physical properties and chemical composition of the cores in the California molecular cloud
We aim to reveal the physical properties and chemical composition of the
cores in the California molecular cloud (CMC), so as to better understand the
initial conditions of star formation. We made a high-resolution column density
map (18.2") with Herschel data, and extracted a complete sample of the cores in
the CMC with the \textsl{fellwalker} algorithm. We performed new
single-pointing observations of molecular lines near 90 GHz with the IRAM 30m
telescope along the main filament of the CMC. In addition, we also performed a
numerical modeling of chemical evolution for the cores under the physical
conditions. We extracted 300 cores, of which 33 are protostellar and 267 are
starless cores. About 51\% (137 of 267) of the starless cores are prestellar
cores. Three cores have the potential to evolve into high-mass stars. The
prestellar core mass function (CMF) can be well fit by a log-normal form. The
high-mass end of the prestellar CMF shows a power-law form with an index
that is shallower than that of the Galactic field stellar
mass function. Combining the mass transformation efficiency ()
from the prestellar core to the star of and the core formation
efficiency (CFE) of 5.5\%, we suggest an overall star formation efficiency of
about 1\% in the CMC. In the single-pointing observations with the IRAM 30m
telescope, we find that 6 cores show blue-skewed profile, while 4 cores show
red-skewed profile. []/[HNC] and []/ in protostellar cores are higher than those in prestellar cores;
this can be used as chemical clocks. The best-fit chemical age of the cores
with line observations is ~years.Comment: Accepted by Astronomy & Astrophysics (A&A
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