49,632 research outputs found
Reflection matrices for the vertex model
The graded reflection equation is investigated for the
vertex model. We have found four classes of diagonal
solutions and twelve classes of non-diagonal ones. The number of free
parameters for some solutions depends on the number of bosonic and fermionic
degrees of freedom considered.Comment: 30 page
Generation of focusing ion beams by magnetized electron sheath acceleration.
We present the first 3D fully kinetic simulations of laser driven sheath-based ion acceleration with a kilotesla-level applied magnetic field. The application of a strong magnetic field significantly and beneficially alters sheath based ion acceleration and creates two distinct stages in the acceleration process associated with the time-evolving magnetization of the hot electron sheath. The first stage delivers dramatically enhanced acceleration, and the second reverses the typical outward-directed topology of the sheath electric field into a focusing configuration. The net result is a focusing, magnetic field-directed ion source of multiple species with strongly enhanced energy and number. The predicted improvements in ion source characteristics are desirable for applications and suggest a route to experimentally confirm magnetization-related effects in the high energy density regime. We additionally perform a comparison between 2D and 3D simulation geometry, on which basis we predict the feasibility of observing magnetic field effects under experimentally relevant conditions
Compact stars within an asy-soft quark-meson-coupling model
We investigate compact star properties within the quark meson coupling model
(QMC) with a soft symmetry energy density dependence at large densities. In
particular, the hyperon content and the mass/radius curves for the families of
stars obtained within the model are discussed. The hyperon-meson couplings are
chosen according to experimental values of the hyperon nuclear matter
potentials, and possible uncertainties are considered. It is shown that a
softer symmetry energy gives rise to stars with less hyperons, smaller radii
and larger masses. Hyperon-meson couplings may also have a strong effect on the
mass of the star.Comment: 7 pages, revtex, accepted in Phys. Rev.
Density Dependent Parametrization Models: Formalism and Applications
In this work we derive a formalism to incorporate asymmetry and temperature
effects in the Brown-Rho (BR) scaled lagrangian model in a mean field theory.
The lagrangian density discussed in this work requires less parameters than the
usual models with density dependent couplings. We also present the formalism
with the inclusion of the eight lightest baryons, two lightest leptons, beta
equilibrium and charge neutrality in order to apply the BR scaled model to the
study of neutron stars. The results are again compared with the ones obtained
from another density dependent parametrization model. The role played by the
rearrangement term at T=0 for nuclear or neutron star matter and at finite
temperature is investigated. The BR scaled model is shown to be a good tool in
studies involving density dependent effective masses and in astrophysics
applications.Comment: 23 pages, 10 figure
Password secured sites: stepping forward with keystroke dynamics
Computer Authentication is a critical component of
most computer systems – especially those used in e-
Commerce activities over the internet. Global access
to information makes security, namely the
authentication process, a critical design issue in these
systems. In what concerns to authentication, what is
required is a reliable, hardware independent and
efficient security system. In this paper, we propose an
extension to a keystroke dynamics based security
system. We provide evidence that completely software
based systems can be as effective as expensive and
cumbersome hardware based systems. Our system is a
behavioral based system that captures the normal
typing patterns of a user and uses that information, in
addition to standard login/password security to
provide a system that is user-friendly and very effective
at detecting imposters. The results provide a means of
dealing with enhanced security that is growing in
demand in web-based applications based on ECommerce
Android Malware Clustering through Malicious Payload Mining
Clustering has been well studied for desktop malware analysis as an effective
triage method. Conventional similarity-based clustering techniques, however,
cannot be immediately applied to Android malware analysis due to the excessive
use of third-party libraries in Android application development and the
widespread use of repackaging in malware development. We design and implement
an Android malware clustering system through iterative mining of malicious
payload and checking whether malware samples share the same version of
malicious payload. Our system utilizes a hierarchical clustering technique and
an efficient bit-vector format to represent Android apps. Experimental results
demonstrate that our clustering approach achieves precision of 0.90 and recall
of 0.75 for Android Genome malware dataset, and average precision of 0.98 and
recall of 0.96 with respect to manually verified ground-truth.Comment: Proceedings of the 20th International Symposium on Research in
Attacks, Intrusions and Defenses (RAID 2017
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