782 research outputs found
Structural and superconducting properties of MgBBe
We prepared MgBBe (, 0.2, 0.3, 0.4, and 0.6) samples where
B is substituted with Be. MgB structure is maintained up to .
In-plane and inter-plane lattice constants were found to decrease and increase,
respectively. Superconducting transition temperature decreases with
. We found that the decrease is correlated with in-plane contraction
but is insensitive to carrier doping, which is consistent with other
substitution studies such as MgAlB and MgBC.
Implication of this work is discussed in terms of the 2D nature of -band.Comment: 3 pages,4 figures, to be published in Phys. Rev.
Marginal Pinning of Quenched Random Polymers
An elastic string embedded in 3D space and subject to a short-range
correlated random potential exhibits marginal pinning at high temperatures,
with the pinning length becoming exponentially sensitive to
temperature. Using a functional renormalization group (FRG) approach we find
, with the
depinning temperature. A slow decay of disorder correlations as it appears in
the problem of flux line pinning in superconductors modifies this result, .Comment: 4 pages, RevTeX, 1 figure inserte
Triquark correlations and pentaquarks in a QCD sum rule approach
The role of quark correlations in the description of hadron dynamics in many
domains of physics, from low energy dynamics to very hot(dense) systems, is
being appreciated. Strong correlations of two quarks (diquark) have been widely
investigated in this respect. Recently, we have proposed a dynamical scheme to
describe the pentaquark in which also three quark correlations
(triquark) were instrumental in producing a low mass exotic state. We perform a
study, within the QCD sum rule approach including OPE and direct instanton
contributions, of triquark correlations and obtain two quasi-bound light
color quark clusters of 800 MeV and 930 MeV respectively.Comment: 11 pages, 9 figures, corrected typos, reference added, introduction
and conclusions modified slightl
MxA as a clinically applicable biomarker for identifying systemic interferon type I in primary Sjögren's syndrome
Objective: To establish an easy and practical assay for identifying systemic interferon (IFN) type I bioactivity in patients with primary Sjögren's syndrome (pSS). The IFN type I signature is present in over half of the pSS patients and identifies a subgroup with a higher disease activity. This signature is currently assessed via laborious expression profiles of multiple IFN type I-inducible genes. Methods: In a cohort of 35 pSS patients, myxovirus-resistance protein A (MxA) was assessed as a potential biomarker for ty
Effects of Pore Walls and Randomness on Phase Transitions in Porous Media
We study spin models within the mean field approximation to elucidate the
topology of the phase diagrams of systems modeling the liquid-vapor transition
and the separation of He--He mixtures in periodic porous media. These
topologies are found to be identical to those of the corresponding random field
and random anisotropy spin systems with a bimodal distribution of the
randomness. Our results suggest that the presence of walls (periodic or
otherwise) are a key factor determining the nature of the phase diagram in
porous media.Comment: REVTeX, 11 eps figures, to appear in Phys. Rev.
Impact of alcohol use disorder severity on human immunodeficiency virus (HIV) viral suppression and CD4 count in three international cohorts of people with HIV.
Alcohol use has been linked to worse human immunodeficiency virus (HIV) immunologic/virologic outcomes, yet few studies have explored the effects of alcohol use disorder (AUD). This study assessed whether AUD severity is associated with HIV viral suppression and CD4 count in the three cohorts of the Uganda Russia Boston Alcohol Network for Alcohol Research Collaboration on HIV/AIDS (URBAN ARCH) Consortium.
People with HIV (PWH) in Uganda (n = 301), Russia (n = 400), and Boston (n = 251), selected in-part based on their alcohol use, were included in analyses. Logistic and linear regressions were used to assess the cross-sectional associations between AUD severity (number of DSM-5 diagnostic criteria) and (1) HIV viral suppression, and (2) CD4 count (cells/mm <sup>3</sup> ) adjusting for covariates. Analyses were conducted separately by site.
The proportion of females was 51% (Uganda), 34% (Russia), and 33% (Boston); mean age (SD) was 40.7 (9.6), 38.6 (6.3), and 52.1 (10.5), respectively. All participants in Uganda and all but 27% in Russia and 5% in Boston were on antiretroviral therapy. In Uganda, 32% met criteria for AUD, 92% in Russia, and 43% in Boston. The mean (SD) number of AUD criteria was 1.6 (2.4) in Uganda, 5.6 (3.3) in Russia, and 2.4 (3.1) in Boston. Most participants had HIV viral suppression (Uganda 92%, Russia 57%, Boston 87%); median (IQR) CD4 count was 673 (506, 866), 351 (201, 542), and 591 (387, 881), respectively. In adjusted models, there were no associations between AUD severity and HIV viral suppression: adjusted odds ratios (AOR) (95%CI) per 1 additional AUD criterion in Uganda was 1.08 (0.87, 1.33); Russia 0.98 (0.92, 1.04); and Boston 0.95 (0.84, 1.08) or CD4 count: mean difference (95%CI) per 1 additional criterion: 5.78 (-7.47, 19.03), -3.23 (-10.91, 4.44), and -8.18 (-24.72, 8.35), respectively.
In three cohorts of PWH, AUD severity was not associated with HIV viral suppression or CD4 count. PWH with AUD in the current era of antiretroviral therapy can achieve virologic control
Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results
The chromosphere is a thin layer of the solar atmosphere that bridges the
relatively cool photosphere and the intensely heated transition region and
corona. Compressible and incompressible waves propagating through the
chromosphere can supply significant amounts of energy to the interface region
and corona. In recent years an abundance of high-resolution observations from
state-of-the-art facilities have provided new and exciting ways of
disentangling the characteristics of oscillatory phenomena propagating through
the dynamic chromosphere. Coupled with rapid advancements in
magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly
investigate the role waves play in supplying energy to sustain chromospheric
and coronal heating. Here, we review the recent progress made in
characterising, categorising and interpreting oscillations manifesting in the
solar chromosphere, with an impetus placed on their intrinsic energetics.Comment: 48 pages, 25 figures, accepted into Space Science Review
The Ultra-luminous M81 X-9 source: 20 years variability and spectral states
The source X-9 was discovered with the {\it Einstein Observatory} in the
field of M81, and is located in the dwarf galaxy Holmberg IX. X-9 has a 0.2-4.0
keV luminosity of ergs~s, if it is at the same
distance as Holmberg IX (3.4 Mpc). This luminosity is above the Eddington
luminosity of a 1~ compact accreting object. Past hypotheses on the
nature of this Super-Eddington source included a SNR or supershell, an
accreting compact object and a background QSO. To shed light on the nature of
this source, we have obtained and analyzed archival data, including the {\it
Einstein} data, 23 ROSAT observations, Beppo-SAX and ASCA pointings. Our
analysis reveals that most of the emission of X-9 arises from a point-like
highly-variable source, and that lower luminosity extended emission may be
associated with it. The spectrum of this source changes between low and high
intensity states, in a way reminiscent of the spectra of galactic Black Hole
candidates. Our result strongly suggest that X-9 is not a background QSO, but a
bonafide `Super-Eddington' source in Ho IX, a dwarf companion of M81.Comment: 31 pages, 10 figures, ApJ - accepted for publicatio
Deficiency in the mRNA export mediator Gle1 impairs Schwann cell development in the zebrafish embryo
GLE1 mutations cause lethal congenital contracture syndrome 1 (LCCS1), a severe autosomal recessive fetal motor neuron disease, and more recently have been associated with amyotrophic lateral sclerosis (ALS). The gene encodes a highly conserved protein with an essential role in mRNA export. The mechanism linking Gle1 function to motor neuron degeneration in humans has not been elucidated, but increasing evidence implicates abnormal RNA processing as a key event in the pathogenesis of several motor neuron diseases. Homozygous gle1−/− mutant zebrafish display various aspects of LCCS, showing severe developmental abnormalities including motor neuron arborization defects and embryonic lethality. A previous gene expression study on spinal cord from LCCS fetuses indicated that oligodendrocyte dysfunction may be an important factor in LCCS. We therefore set out to investigate the development of myelinating glia in gle1−/− mutant zebrafish embryos. While expression of myelin basic protein (mbp) in hindbrain oligodendrocytes appeared relatively normal, our studies revealed a prominent defect in Schwann cell precursor proliferation and differentiation in the posterior lateral line nerve. Other genes mutated in LCCS have important roles in Schwann cell development, thereby suggesting that Schwann cell deficits may be a common factor in LCCS pathogenesis. These findings illustrate the potential importance of glial cells such as myelinating Schwann cells in motor neuron diseases linked to RNA processing defects
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