635 research outputs found
Calculation of Effective Coulomb Interaction for , , and
In this paper, the Slater integrals for a screened Coulomb interaction of the
the Yukawa form are calculated and by fitting the Thomas-Fermi wavevector, good
agreement is obtained with experiment for the multiplet spectra of
and ions. Moreover, a predicted multiplet spectrum for the heavy
fermion superconductor is shown with a calculated Coulomb U of 1.6 eV.
These effective Coulomb interactions, which are quite simple to calculate,
should be useful inputs to further many-body calculations in correlated
electron metals.Comment: 8 pages, revtex, 3 uuencoded postscript figure
On the spherical-axial transition in supernova remnants
A new law of motion for supernova remnant (SNR) which introduces the quantity
of swept matter in the thin layer approximation is introduced. This new law of
motion is tested on 10 years observations of SN1993J. The introduction of an
exponential gradient in the surrounding medium allows to model an aspherical
expansion. A weakly asymmetric SNR, SN1006, and a strongly asymmetric SNR,
SN1987a, are modeled. In the case of SN1987a the three observed rings are
simulated.Comment: 19 figures and 14 pages Accepted for publication in Astrophysics &
Space Science in the year 201
Fine Root Productivity and Dynamics on a Forested Floodplain in South Carolina
The highly dynamic, fine-root component of forested wetland ecosystems has received inadequate attention in the literature. Characterizing fine root dynamics is a challenging endeavor in any system, but the difficulties are particularly evident in forested floodplains where frequent hydrologic fluctuations directly influence fine root dynamics. Fine root (\u3c 3mm) biomass, production, and turnover were estimated for three soils exhibiting different drainage patterns within a mixed-oak community on the Coosawhatchie River floodplain, Jasper County, SC. Within a 45-cm deep vertical profile, 74% of total fine root biomass was restricted to the upper 15 cm of the soil surface. Fine root biomass decreased as the soil became less well-drained (e.g., fine root biomass in well-drained soil \u3e intermediately drained soil \u3e poorly drained soil). Fine root productivity was measured for one year using minirhizotrons and in-situ screens. Both methods suggested higher fine root production in better drained soils but showed frequent fluctuations in fine root growth and mortality, suggesting the need for frequent sampling at short intervals (e.g., monthly) to accurately assess fine root growth and turnover. Fine root production, estimated with in-situ screens, was 1.5, 1.8, and 0.9 Mg ha-1 yr-1 in the well-drained, intermediately drained, and poorly drained soils, respectively. Results from minirhizotrons indicated that fine roots in well-drained soils grew to greater depths while fine roots in poorly drained soils were restricted to surface soils. Minirhizotrons also revealed that the distribution of fine roots among morphological classes changed between well-drained and poorly drained soils
Probing the Local Velocity Distribution of WIMP Dark Matter with Directional Detectors
We explore the ability of directional nuclear-recoil detectors to constrain
the local velocity distribution of weakly interacting massive particle (WIMP)
dark matter by performing Bayesian parameter estimation on simulated
recoil-event data sets. We discuss in detail how directional information, when
combined with measurements of the recoil-energy spectrum, helps break
degeneracies in the velocity-distribution parameters. We also consider the
possibility that velocity structures such as cold tidal streams or a dark disk
may also be present in addition to the Galactic halo. Assuming a
carbon-tetrafluoride detector with a 30-kg-yr exposure, a 50-GeV WIMP mass, and
a WIMP-nucleon spin-dependent cross-section of 0.001 pb, we show that the
properties of a cold tidal stream may be well constrained. However, measurement
of the parameters of a dark-disk component with a low lag speed of ~50 km/s may
be challenging unless energy thresholds are improved.Comment: 38 pages, 15 figure
Quantum Correlation in One-dimensional Extend Quantum Compass Model
We study the correlations in the one-dimensional extended quantum compass
model in a transverse magnetic field. By exactly solving the Hamiltonian, we
find that the quantum correlation of the ground state of one-dimensional
quantum compass model is vanishing. We show that quantum discord can not only
locate the quantum critical points, but also discern the orders of phase
transitions. Furthermore, entanglement quantified by concurrence is also
compared.Comment: 8 pages, 14 figures, to appear in Eur. Phys. J.
Studying Brugada syndrome with an SCN1B variants in human-induced pluripotent stem cell-derived cardiomyocytes
BACKGROUND: Among rare channelopathies BrS patients are at high risk of sudden cardiac death (SCD). SCN5A mutations are found in a quarter of patients. Other rare gene mutations including SCN1B have been implicated to BrS. Studying the human cellular phenotype of BrS associated with rare gene mutation remains lacking. OBJECTIVES: We sought to study the cellular phenotype of BrS with the SCN1B gene variants using human-induced pluripotent stem cell (hiPSCs)–derived cardiomyocytes (hiPSC-CMs). METHODS AND RESULTS: A BrS patient suffering from recurrent syncope harboring a two variants (c.629T > C and c.637C > A) in SCN1B, which encodes the function-modifying sodium channel beta1 subunit, and three independent healthy subjects were recruited and their skin biopsies were used to generate hiPSCs, which were differentiated into cardiomyocytes (hiPSC-CMs) for studying the cellular electrophysiology. A significantly reduced peak and late sodium channel current (I(Na)) and a shift of activation curve to more positive potential as well as a shift of inactivation curve to more negative potential were detected in hiPSC-CMs of the BrS patient, indicating that the SCN1B variants impact the function of sodium channels in cardiomyocytes. The reduced I(Na) led to a reduction of amplitude (APA) and upstroke velocity (V(max)) of action potentials. Ajmaline, a sodium channel blocker, showed a stronger effect on APA and Vmax in BrS cells as compared to cells from healthy donors. Furthermore, carbachol was able to increase arrhythmia events and the beating frequency in BrS. CONCLUSION: Our hiPSC-CMs from a BrS-patient with two variants in SCN1B recapitulated some key phenotypic features of BrS and can provide a platform for studies on BrS with SCN1B variants
Gravitational Wave Emission From a Binary Black Hole System in Presence of an Accretion Disk
We study time evolution and gravitational wave emission properties of a black
hole orbiting {\it inside} an accretion disk surrounding a massive black hole.
We simultaneously solve the structure equations of the accretion disk in
presence of heating, cooling and viscosity as well as the equations governing
the companion orbit. The deviation from Keplerian distribution of angular
momentum of the disk due to pressure and advection effects causes a significant
exchange of angular momentum between the disk and the companion. This
significantly affects the gravitational wave emission properties from the
binary system. We show that when the companion is light, the effect is
extremely important and must be taken into account while interpreting
gravitational wave signals from such systems.Comment: 8 pages of Latex plus postscript fil
Time-Dependent Models for a decade of SN 1993J
A classical and a relativistic law of motion for a supernova remnant (SNR)
are deduced assuming an inverse power law behavior for the density of the
interstellar medium and applying the thin layer approximation. A third equation
of motion is found in the framework of relativistic hydrodynamics with
pressure, applying momentum conservation. These new formulas are calibrated
against a decade of observations of \snr. The existing knowledge of the
diffusive processes of ultrarelativistic electrons is reviewed in order to
explain the behavior of the `U' shaped profile of intensity versus distance
from the center of SN 1993J.Comment: 20 pages 19 figures, Accepted for pubblication in Astrophysics and
Space Science 201
Synthesis and DPPH scavenging assay of reserpine analogues, computational studies and in silico docking studies in AChE and BChE responsible for Alzheimer's disease
Alzheimer's disease (AD) is a fast growing neurodegenerative disorder of the central nervous system and anti-oxidants can be used to help suppress the oxidative stress caused by the free radicals that are responsible for AD. A series of selected synthetic indole derivatives were biologically evaluated to identify potent new antioxidants. Most of the evaluated compounds showed significant to modest antioxidant properties (IC50 value 399.07 140.0±50 µM). Density Functional Theory (DFT) studies were carried out on the compounds and their corresponding free radicals. Differences in the energy of the parent compounds and their corresponding free radicals provided a good justification for the trend found in their IC50 values. In silico, docking of compounds into the proteins acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), which are well known for contributing in AD disease, was also performed to predict anti-AD potential
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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