8,821 research outputs found
On particle acceleration and trapping by Poynting flux dominated flows
Using particle-in-cell (PIC) simulations, we study the evolution of a
strongly magnetized plasma slab propagating into a finite density ambient
medium. Like previous work, we find that the slab breaks into discrete magnetic
pulses. The subsequent evolution is consistent with diamagnetic relativistic
pulse acceleration of \cite{liangetal2003}. Unlike previous work, we use the
actual electron to proton mass ratio and focus on understanding trapping vs.
transmission of the ambient plasma by the pulses and on the particle
acceleration spectra. We find that the accelerated electron distribution
internal to the slab develops a double-power law. We predict that emission from
reflected/trapped external electrons will peak after that of the internal
electrons. We also find that the thin discrete pulses trap ambient electrons
but allow protons to pass through, resulting in less drag on the pulse than in
the case of trapping of both species. Poynting flux dominated scenarios have
been proposed as the driver of relativistic outflows and particle acceleration
in the most powerful astrophysical jets.Comment: 25 pages, Accepted by Plasma Physics and Controlled Fusio
ARGG-HDL: A High Level Python Based Object-Oriented HDL Framework
We present a High-Level Python-based Hardware Description Language
(ARGG-HDL), It uses Python as its source language and converts it to standard
VHDL. Compared to other approaches of building converters from a high-level
programming language into a hardware description language, this new approach
aims to maintain an object-oriented paradigm throughout the entire process.
Instead of removing all the high-level features from Python to make it into an
HDL, this approach goes the opposite way. It tries to show how certain features
from a high-level language can be implemented in an HDL, providing the
corresponding benefits of high-level programming for the user
The Supersymmetric Ward-Takahashi Identity in 1-Loop Lattice Perturbation Theory. I. General Procedure
The one-loop corrections to the lattice supersymmetric Ward-Takahashi
identity (WTi) are investigated in the off-shell regime. In the Wilson
formulation of the N=1 supersymmetric Yang-Mills (SYM) theory, supersymmetry
(SUSY) is broken by the lattice, by the Wilson term and is softly broken by the
presence of the gluino mass. However, the renormalization of the supercurrent
can be realized in a scheme that restores the continuum supersymmetric WTi
(once the on-shell condition is imposed). The general procedure used to
calculate the renormalization constants and mixing coefficients for the local
supercurrent is presented. The supercurrent not only mixes with the gauge
invariant operator . An extra mixing with other operators coming from
the WTi appears. This extra mixing survives in the continuum limit in the
off-shell regime and cancels out when the on-shell condition is imposed and the
renormalized gluino mass is set to zero. Comparison with numerical results are
also presented.Comment: 16 pages, 2 figures. Typos error correcte
Femoral Osteomyelitis due to Cladophialophora arxii in a Patient with Chronic Granulomatous Disease
Fungal infections in patients with chronic granulomatous disease (CGD) are a poor prognostic factor. We describe the first case of CGD with femoral osteomyelitis due to Cladophialophora arxii, which is a member of the dematiaceous group. The causative fungus was identified on the basis of its morphological characteristics, growth temperature profile, and nucleotide sequence on the internal transcribed space region of the ribosomal gene. The patient was successfully treated with surgical debridement, subsequent administration of itraconazolem and interferon-gamma.ArticleINFECTION. 37(5):469-473 (2009)journal articl
The Most Likely Sources of High Energy Cosmic-Ray Electrons in Supernova Remnants
Evidences of non-thermal X-ray emission and TeV gamma-rays from the supernova
remnants (SNRs) has strengthened the hypothesis that primary Galactic
cosmic-ray electrons are accelerated in SNRs. High energy electrons lose energy
via synchrotron and inverse Compton processes during propagation in the Galaxy.
Due to these radiative losses, TeV electrons liberated from SNRs at distances
larger than ~1 kpc, or times older than ~10^5 yr, cannot reach the solar
system. We investigated the cosmic-ray electron spectrum observed in the solar
system using an analytical method, and considered several candidate sources
among nearby SNRs which may contribute to the high energy electron flux.
Especially, we discuss the effects for the release time from SNRs after the
explosion, as well as the deviation of a source spectrum from a simple
power-law. From this calculation, we found that some nearby sources such as the
Vela, Cygnus Loop, or Monogem could leave unique signatures in the form of
identifiable structure in the energy spectrum of TeV electrons and show
anisotropies towards the sources, depending on when the electrons are liberated
from the remnant. This suggests that, in addition to providing information on
the mechanisms of acceleration and propagation of cosmic-rays, specific
cosmic-ray sources can be identified through the precise electron observation
in the TeV region.Comment: 32 pages, 6 figures, submitted to Ap
14-MeV Neutron Irradiation Effects on Superconducting Magnet Materials under Cryogenic Temperature
Detection of a Hard Tail in the X-ray Spectrum of the Z Source GX 349+2
We present the results of a BeppoSAX observation of the Z source GX 349+2
covering the energy range 0.1-200 keV. The presence of flares in the light
curve indicates that the source was in the flaring branch during the BeppoSAX
observation. We accumulated energy spectra separately for the non-flaring
intervals and the flares. In both cases the continuum is well described by a
soft blackbody ( keV) and a Comptonized spectrum
corresponding to an electron temperature of keV, optical depth
(for a spherical geometry), and seed photon temperature of keV. All temperatures tend to increase during the flares. In the
non-flaring emission a hard tail dominates the spectrum above 30 keV. This can
be fit by a power law with photon index , contributing of the
total source luminosity over the BeppoSAX energy range. A comparison with hard
tails detected in some soft states of black hole binaries suggests that a
similar mechanism could originate these components in black hole and neutron
star systems.Comment: 15 pages, including 8 figures, to appear in Ap
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