214 research outputs found
Small-RNA characterization of Coffee Leaf Rust races having different virulence profiles
info:eu-repo/semantics/publishedVersio
Determination of the average ionization and thermodynamic regimes of xenon plasmas with an application to the characterization of blast waves launched in xenon clusters
Radiative shock waves play a pivotal role in the transport energy into the stellar medium. This fact has led to many efforts to scale the astrophysical phenomena to accessible laboratory conditions and their study has been highlighted as an area requiring further experimental investigations. Low density material with high atomic mass is suitable to achieve radiative regime, and, therefore, low density xenon gas is commonly used for the medium in which the radiative shock propagates. In this work the averageionization and the thermodynamicregimes of xenonplasmas are determined as functions of the matter density and temperature in a wide range of plasma conditions. The results obtained will be applied to characterize blastwaveslaunched in xenoncluster
Determination and analysis of plasma radiative properties for numerical simulations of laboratory radiative blast waves launched in xenon clusters
Radiative shock waves play a pivotal role in the transport energy into the stellar medium. This fact has led to many efforts to scale the astrophysical phenomena to accessible laboratory conditions and their study has been highlighted as an area requiring further experimental investigations. Low density material with high atomic mass is suitable to achieve radiative regime, and, therefore, low density xenon plasmas are commonly used for the medium in which the radiative shocks propagate. The knowledge of the plasma radiative properties is crucial for the correct understanding and for the hydrodynamic simulations of radiative shocks. In this work, we perform an analysis of the radiative properties of xenon plasmas in a range of matter densities and electron temperatures typically found in laboratory experiments of radiative shocks launched in xenon plasmas. Furthermore, for a particular experiment, our analysis is applied to make a diagnostics of the electron temperatures of the radiative shocks since they could not be experimentally measure
The quantum J_{1}-J_{1'}-J_{2} spin-1/2 Heisenberg antiferromagnet: A variational method study
The phase transition of the quantum spin-1/2 frustrated Heisenberg
antiferroferromagnet on an anisotropic square lattice is studied by using a
variational treatment. The model is described by the Heisenberg Hamiltonian
with two antiferromagnetic interactions: nearest-neighbor (NN) with different
coupling strengths J_{1} and J_{1'} along x and y directions competing with a
next-nearest-neighbor coupling J_{2} (NNN). The ground state phase diagram in
the ({\lambda},{\alpha}) space, where {\lambda}=J_{1'}/J_{1} and
{\alpha}=J_{2}/J_{1}, is obtained. Depending on the values of {\lambda} and
{\alpha}, we obtain three different states: antiferromagnetic (AF), collinear
antiferromagnetic (CAF) and quantum paramagnetic (QP). For an intermediate
region {\lambda}_{1}<{\lambda}<1 we observe a QP state between the ordered AF
and CAF phases, which disappears for {\lambda} above some critical value
{\lambda}_{1}. The boundaries between these ordered phases merge at the quantum
critical endpoint (QCE). Below this QCE there is again a direct first-order
transition between the AF and CAF phases, with a behavior approximately
described by the classical line {\alpha}_{c}{\simeq}{\lambda}/2
Analysis of microscopic magnitudes of radiative blast waves launched in xenon clusters with collisional-radiative steady-state simulations
Radiative shock waves play a pivotal role in the transport energy into the stellar medium. This fact has led to many efforts to scale the astrophysical phenomena to accessible laboratory conditions and their study has been highlighted as an area requiring further experimental investigations. Low density material with high atomic mass is suitable to achieve radiative regime, and, therefore, low density xenon gas is commonly used for the medium in which the radiative shocks such as radiative blast waves propagate. In this work, by means of collisional-radiative steady-state calculations, a characterization and an analysis of microscopic magnitudes of laboratory blast waves launched in xenon clusters are made. Thus, for example, the average ionization, the charge state distribution, the cooling time or photon mean free paths are studied. Furthermore, for a particular experiment, the effects of the self-absorption and self-emission in the specific intensity emitted by the shock front and that is going through the radiative precursor are investigated. Finally, for that experiment, since the electron temperature is not measured experimentally, an estimation of this magnitude is made both for the shock shell and the radiative precursor
Quasinormal modes for massless topological black holes
An exact expression for the quasinormal modes of scalar perturbations on a
massless topological black hole in four and higher dimensions is presented. The
massive scalar field is nonminimally coupled to the curvature, and the horizon
geometry is assumed to have a negative constant curvature.Comment: CECS style, 11 pages, no figures. References adde
Propagator of a Charged Particle with a Spin in Uniform Magnetic and Perpendicular Electric Fields
We construct an explicit solution of the Cauchy initial value problem for the
time-dependent Schroedinger equation for a charged particle with a spin moving
in a uniform magnetic field and a perpendicular electric field varying with
time. The corresponding Green function (propagator) is given in terms of
elementary functions and certain integrals of the fields with a characteristic
function, which should be found as an analytic or numerical solution of the
equation of motion for the classical oscillator with a time-dependent
frequency. We discuss a particular solution of a related nonlinear Schroedinger
equation and some special and limiting cases are outlined.Comment: 17 pages, no figure
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