1,458 research outputs found
Effective Vortex Mass from Microscopic Theory
We calculate the effective mass of a single quantized vortex in the BCS
superconductor at finite temperature. Based on effective action approach, we
arrive at the effective mass of a vortex as integral of the spectral function
divided by over frequency. The spectral function is
given in terms of the quantum-mechanical transition elements of the gradient of
the Hamiltonian between two Bogoliubov-deGennes (BdG) eigenstates. Based on
self-consistent numerical diagonalization of the BdG equation we find that the
effective mass per unit length of vortex at zero temperature is of order (=Fermi momentum, =coherence length), essentially
equaling the electron mass displaced within the coherence length from the
vortex core. Transitions between the core states are responsible for most of
the mass. The mass reaches a maximum value at and decreases
continuously to zero at .Comment: Supercedes prior version, cond-mat/990312
AGRICULTURAL VALUE ADDED: PROSPECTS FOR NORTH DAKOTA
Introduction: This report provides an overview of the important factors affecting investments in agricultural value-added ventures. The introductory section outlines current research on factors important in the location of economic activity. Research applied to specific agricultural value-added ventures, such as food manufacturing and livestock feeding and finishing operations, are discussed. A listing of resources available to entrepreneurs considering value-added investments concludes the introductory section. Following the introductory section are short overviews of industries that already have, or may have, potential for increasing economic activity in the state. All are based on the important foundation of agriculture in the state's economy or upon the natural resource base giving the state a comparative advantage in investments in alternative energy or resource-based recreation.Agribusiness,
A systematic review of the epidemiology of hepatitis E virus in Africa
BACKGROUND: Hepatitis E Virus (HEV) infection is a newly recognized serious threat to global public health and Africa is suspected to be among the most severely affected regions in the world. Understanding HEV epidemiology in Africa will expedite the implementation of evidence-based control policies aimed at preventing the spread of HEV including policies for the use of available resources such as HEV vaccines. METHODS: Here we present a comprehensive review of HEV epidemiology in Africa based on published data. We searched for articles on HEV epidemiology in Africa from online databases such as PubMed, Scopus, and ISI Web of Science and critically reviewed appropriate publications to extract consistent findings, identify knowledge gaps, and suggest future studies. RESULTS: Taking a particularly high toll in pregnant women and their fetuses, HEV has infected human populations in 28 of 56 African countries. Since 1979, 17 HEV outbreaks have been reported about once every other year from Africa causing a reported 35,300 cases with 650 deaths. CONCLUSIONS: In Africa, HEV infection is not new, is widespread, and the number of reported outbreaks are likely a significant underestimate. The authors suggest that this is a continent-wide public health problem that deserves the attention of local, regional and international agencies to implement control policies that can save numerous lives, especially those of pregnant women and their fetuses
Efficacy of multivalent recombinant herpesvirus of turkey vaccines against high pathogenicity avian influenza, infectious bursal disease, and Newcastle disease viruses
Vaccines are an essential tool for the control of viral infections in domestic animals. We generated recombinant vector herpesvirus of turkeys (vHVT) vaccines expressing computationally optimized broadly reactive antigen (COBRA) H5 of avian influenza virus (AIV) alone (vHVT-AI) or in combination with virus protein 2 (VP2) of infectious bursal disease virus (IBDV) (vHVT-IBD-AI) or fusion (F) protein of Newcastle disease virus (NDV) (vHVT-ND-AI). In vaccinated chickens, all three vHVT vaccines provided 90–100% clinical protection against three divergent clades of high pathogenicity avian influenza viruses (HPAIVs), and significantly decreased number of birds and oral viral shedding titers at 2 days post-challenge compared to shams. Four weeks after vaccination, most vaccinated birds had H5 hemagglutination inhibition antibody titers, which significantly increased post-challenge. The vHVT-IBD-AI and vHVT-ND-AI vaccines provided 100% clinical protection against IBDVs and NDV, respectively. Our findings demonstrate that multivalent HVT vector vaccines were efficacious for simultaneous control of HPAIV and other viral infections.info:eu-repo/semantics/publishedVersio
Diffusive Ionization of Relativistic Hydrogen-Like Atom
Stochastic ionization of highly excited relativistic hydrogenlike atom in the
monochromatic field is investigated. A theoretical analisis of chaotic dynamics
of the relativistic electron based on Chirikov criterion is given for the cases
of one- and three-dimensional atoms. Critical value of the external field is
evaluated analitically. The diffusion coefficient and ionization time are
calculated.Comment: 13 pages, latex, no figures, submitted to PR
Dynamics of false vacuum bubbles in Brans-Dicke theory
We study the dynamics of false vacuum bubbles in the Brans-Dicke theory of
gravity by using the thin shell or thin wall approximation. We consider a false
vacuum bubble that has a different value for the Brans-Dicke field between the
inside false vacuum region and the outside true vacuum region. Within a certain
limit of field values, the difference of field values makes the effective
tension of the shell negative. This allows new expanding false vacuum bubbles
to be seen by the outside observer, which are disallowed in Einstein gravity.Comment: 29 pages, 20 figure
SO/Sp Monopoles and Branes with Orientifold 3 Plane
We study BPS monopoles in 4 dimensional N=4 SO(N) and super
Yang-Mills theories realized as the low energy effective theory of
(physical and its mirror) parallel D3 branes and an {\it Orientifold 3 plane}
with D1 branes stretched between them in type IIB string theory. Monopoles on
D3 branes give the natural understanding by embedding in SU(N) through the
constraints on both the asymptotic Higgs field (corresponding to the horizontal
positions of D3 branes) and the magnetic charges (corresponding to the number
of D1 branes) imposed by the O3 plane. The compatibility conditions of Nahm
data for monopoles for these groups can be interpreted very naturally through
the D1 branes in the presence of O3 plane.Comment: 18 pages, Latex with RevTex, 1 table, 4 figures, v2: Clarified the
introduction and improved on the supersymmetric theory on D1 branes in page 7
and 8 and this final version to appear in Phys.Rev.
The probability to initiate X chromosome inactivation is determined by the X to autosomal ratio and x chromosome specific allelic properties.
Background: In female mammalian cells, random X chromosome inactivation (XCI) equalizes the dosage of X-encoded gene products to that in male cells. XCI is a stochastic process, in which each X chromosome has a probability to be inactivated. To obtain more insight in the factors setting up this probability, we studied the role of the X to autosome (X:A) ratio in initiation of XCI, and have used the experimental data in a computer simulation model to study the cellular population dynamics of XCI. Methodology/Principal Findings: To obtain more insight in the role of the X:A ratio in initiation of XCI, we generated triploid mouse ES cells by fusion of haploid round spermatids with diploid female and male ES cells. These fusion experiments resulted in only XXY triploid ES cells. XYY and XXX ES lines were absent, suggesting cell death related either to insufficient X-chromosomal gene dosage (XYY) or to inheritance of an epigenetically modified X chromosome (XXX). Analysis of active (Xa) and inactive (Xi) X chromosomes in the obtained triploid XXY lines indicated that the initiation frequency of XCI is low, resulting in a mixed population of XaXiY and XaXaY cells, in which the XaXiY cells have a small proliferative advantage. This result, and findings on XCI in diploid and tetraploid ES cell lines with different X:A ratios, provides evidence that the X:A ratio determines the probability for a given X chromosome to be inactivated. Furthermore, we found that the kinetics of the XCI process can be simulated using a probability for an X chromosome to be inactivated that is proportional to the X:A ratio. These simulation studies re-emphasize our hypothesis that the probability is a function of the concentration of an X-encoded activator of XCI, and of X chromosome specific allelic properties determining the threshold for this activator. Conclusions: The present findings reveal that the probability for an X chromosome to be inactivated is proportional to the X:A ratio. This finding supports the presence of an X-encoded activator of the XCI process. © 2009 Monkhorst et al
Coupling of localized moments and itinerant electrons in EuFe2As2 single crystals studied by Electron Spin Resonance
Electron spin resonance measurements in EuFe2As2 single crystals revealed an
absorption spectrum of a single resonance with Dysonian lineshape. Above the
spin-density wave transition at T_SDW = 190 K the spectra are isotropic and the
spin relaxation is strongly coupled to the CEs resulting in a Korringa-like
increase of the linewidth. Below T_SDW, a distinct anisotropy develops and the
relaxation behavior of the Eu spins changes drastically into one with
characteristic properties of a magnetic insulating system, where dipolar and
crystal-field interactions dominate. This indicates a spatial confinement of
the conduction electrons to the FeAs layers in the SDW state.Comment: 4 pages, 4 figure
Quantum Aspects of Supersymmetric Maxwell Chern-Simons Solitons
We study the various quantum aspects of the supersymmetric Maxwell
Chern-Simons vortex systems. The fermion zero modes around the vortices will
give rise the degenerate states of vortices. We analyze the angular momentum of
these zero modes and apply the result to get the supermultiplet structures of
the vortex. The leading quantum correction to the mass of the vortex coming
from the mode fluctuations is also calculated using various methods depending
on the value of the coefficient of the Chern-Simons term to be zero,
infinite and finite, separately. The mass correction is shown to vanish for all
cases. Fermion numbers of vortices are also discussed.Comment: 40 pages, ReVTeX, HYUPT-94/04 SNUTP 94-6
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