4,019 research outputs found
First principles investigation of transition-metal doped group-IV semiconductors: RY (R=Cr, Mn, Fe; Y=Si, Ge)
A number of transition-metal (TM) doped group-IV semiconductors,
RY (R=Cr, Mn and Fe; Y=Si, Ge), have been studied by the first
principles calculations. The obtained results show that antiferromagnetic (AFM)
order is energetically more favored than ferromagnetic (FM) order in Cr-doped
Ge and Si with =0.03125 and 0.0625. In 6.25% Fe-doped Ge, FM interaction
dominates in all range of the R-R distances while for Fe-doped Ge at 3.125% and
Fe-doped Si at both concentrations of 3.125% and 6.25%, only in a short R-R
range can the FM states exist. In the Mn-doped case, the RKKY-like mechanism
seems to be suitable for the Ge host matrix, while for the Mn-doped Si, the
short-range AFM interaction competes with the long-range FM interaction. The
different origin of the magnetic orders in these diluted magnetic
semiconductors (DMSs) makes the microscopic mechanism of the ferromagnetism in
the DMSs more complex and attractive.Comment: 14 pages, 2 figures, 6 table
Ethnobotanical Survey of Medicinal Plants in West Kordofan (Western Sudan)
The aim of the present study was primarily to evaluate the medicinal uses of the plants known to some western Kordofan tribes and to encourage preservation of their culture, conservation and sustainable utilization of the plant wealth. The present study revealed a record of 49 plant species belonging to 26 families which are used in the folk medicine of West Kordofan, Sudan. It is believed to be a form of healthcare in many aspects of curing practices. The plants were arranged alphabetically by their family name followed by species name, local name, parts used, mode of preparation and medicinal uses. This wisdom available with the tribes is transmitted only through oral communication therefore needs conservation
Electron-muon correlation as a new probe to strongly interacting quark-gluon plasma
As a new and clean probe to the strongly interacting quark-gluon plasma
(sQGP), we propose an azimuthal correlation of an electron and a muon which
originate from the semileptonic decay of charm and bottom quarks. By solving
the Langevin equation for the heavy quarks under the hydrodynamic evolution of
the hot plasma, we show that substantial quenching of the away-side peak in the
electron-muon correlation can be seen if the sQGP drag force acting on heavy
quarks is large enough as suggested from the gauge/gravity correspondence. The
effect could be detected in high-energy heavy-ion collisions at the
Relativistic Heavy Ion Collider and the Large Hadron Collider.Comment: 4 pages, 2 figure
Non-autonomous stochastic evolution equations and applications to stochastic partial differential equations
In this paper we study the following non-autonomous stochastic evolution
equation on a UMD Banach space with type 2,
{equation}\label{eq:SEab}\tag{SE} {{aligned} dU(t) & = (A(t)U(t) + F(t,U(t)))
dt + B(t,U(t)) dW_H(t), \quad t\in [0,T],
U(0) & = u_0. {aligned}. {equation}
Here are unbounded operators with domains
which may be time dependent. We assume that
satisfies the conditions of Acquistapace and Terreni. The
functions and are nonlinear functions defined on certain interpolation
spaces and is the initial value. is a cylindrical Brownian
motion on a separable Hilbert space .
Under Lipschitz and linear growth conditions we show that there exists a
unique mild solution of \eqref{eq:SEab}. Under assumptions on the interpolation
spaces we extend the factorization method of Da Prato, Kwapie\'n, and Zabczyk,
to obtain space-time regularity results for the solution of
\eqref{eq:SEab}. For Hilbert spaces we obtain a maximal regularity result.
The results improve several previous results from the literature.
The theory is applied to a second order stochastic partial differential
equation which has been studied by Sanz-Sol\'e and Vuillermot. This leads to
several improvements of their result.Comment: Accepted for publication in Journal of Evolution Equation
An analytically solvable model of the effect of magnetic breakdown on angle-dependent magnetoresistance in a quasi-two-dimensional metal
We have developed an analytical model of angle-dependent magnetoresistance
oscillations (AMROs) in a quasi-two-dimensional metal in which magnetic
breakdown occurs. The model takes account of all the contributions from
quasiparticles undergoing both magnetic breakdown and Bragg reflection at each
junction and allows extremely efficient simulation of data which can be
compared with recent experimental results on the organic metal
kappa-ET2Cu(NCS)2. AMROs resulting from both closed and open orbits emerge
naturally at low field, and the model enables the transition to breakdown-AMROs
with increasing field to be described in detail.Comment: 4 pages, 3 figure
Effect of ethoxyformic anhydride on the Rieske ironâsulfur protein of bovine heart ubiquinol: Cytochrome c oxidoreductase
AbstractTreatment of bovine heart ubiquinol-cytochrome c oxidoreductase (complex III, bc1 complex) with ethoxyformic anhydride (EFA) inhibits electron transfer between cytochromes b and c1 [Yagi et al., Biochemistry 21 (1982) 4777â4782]. This paper shows that EFA alters the EPR lineshape of the Rieske ironâsulfur cluster in complex III and in the isolated Rieske protein without a significant decrease of spin concentration. The effect of EFA on the Rieske ironâsulfur cluster is competitive with that of Qo site inhibitors, such as stigmatellin, and is completely reversed by hydroxylamine. These results are consistent with the possible ethoxyformylation by EFA of histidine ligands of the Rieske ironâsulfur cluster at the non-iron binding imidazole nitrogens
Probing the evolution of early-type galaxies using multi-colour number counts and redshift distributions
We investigate pure luminosity evolution models for early-type (elliptical
and S0) galaxies (i.e., no number density change or morphology transition), and
examine whether these models are consistent with observed number counts in the
B, I and K bands and redshift distributions of two samples of faint galaxies
selected in the I and K bands. The models are characterized by the star
formation time scale and the time when galactic wind blows
in addition to several other conventional parameters. We find the single-burst
model (=0.1 Gyr and =0.353 Gyr), which is known to reproduce
the photometric properties of early-type galaxies in clusters, is inconsistent
with redshift distributions of early-type galaxies in the field environment due
to overpredictions of galaxies at z\gsim1.4 even with strong extinction which
is at work until . In order for dust extinction to be more effective,
we change and as free parameters, and find that models
with \tau_{SF}\gsim0.5 Gyr and Gyr can be made consistent with
both the observed redshift distributions and number counts, if we introduce
strong extinction as a peak value). These results suggest that
early-type galaxies in the field environment do not have the same evolutionary
history as described by the single-burst model.Comment: 6 pages including 4 PS figures; accepted for publication in MNRA
Transition from resistive-6 to ηi-driven turbulence in stellarator systems
B.âG. Hong et al., Physics of Fluids B: Plasma Physics 3, 1638 (1991) https://doi.org/10.1063/1.85968
The Halpha Luminosity Function of the Galaxy Cluster Abell 521 at z = 0.25
We present an optical multicolor-imaging study of the galaxy cluster Abell
521 at , using Suprime-Cam on the Subaru Telescope, covering an area
of arcmin ( Mpc at ). Our imaging data taken with both a narrow-band filter,
(\AA and \AA), and broad-band filters,
, and allow us to find 165 H
emitters. We obtain the H luminosity function (LF) for the cluster
galaxies within 2 Mpc; the Schechter parameters are ,
Mpc, and erg s. Although the faint end slope, , is consistent with
that of the local cluster H LFs, the characteristic luminosity,
, is about 6 times (or mag) brighter. This strong
evolution implies that Abell 521 contains more active star-forming galaxies
than the local clusters, being consistent with the observed Butcher-Oemler
effect. However, the bright of Abell 521 may be, at least in part,
due to the dynamical condition of this cluster.Comment: 21 pages, 7 figures, ApJ, Part 1, in pres
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