37,689 research outputs found
Second Order Noncommutative Corrections to Gravity
In this work, we calculate the leading order corrections to general
relativity formulated on a canonical noncommutative spacetime. These
corrections appear in the second order of the expansion in theta. First order
corrections can only appear in the gravity-matter interactions. Some
implications are briefly discussed.Comment: 10 page
A numerical finite size scaling approach to many-body localization
We develop a numerical technique to study Anderson localization in
interacting electronic systems. The ground state of the disordered system is
calculated with quantum Monte-Carlo simulations while the localization
properties are extracted from the ``Thouless conductance'' , i.e. the
curvature of the energy with respect to an Aharonov-Bohm flux. We apply our
method to polarized electrons in a two dimensional system of size . We
recover the well known universal one
parameter scaling function without interaction. Upon switching on the
interaction, we find that is unchanged while the system flows toward
the insulating limit. We conclude that polarized electrons in two dimensions
stay in an insulating state in the presence of weak to moderate
electron-electron correlations.Comment: 5 pages, 4 figure
Noncommutative General Relativity
We define a theory of noncommutative general relativity for canonical
noncommutative spaces. We find a subclass of general coordinate transformations
acting on canonical noncommutative spacetimes to be volume-preserving
transformations. Local Lorentz invariance is treated as a gauge theory with the
spin connection field taken in the so(3,1) enveloping algebra. The resulting
theory appears to be a noncommutative extension of the unimodular theory of
gravitation. We compute the leading order noncommutative correction to the
action and derive the noncommutative correction to the equations of motion of
the weak gravitation field.Comment: v2: 10 pages, Discussion on noncommutative coordinate transformations
has been changed. Corresponding changes have been made throughout the pape
Secalonic acid A from Pseudoparmelia sphaerospora (Nyl.) Hale and P. hypomilta (Fée) Hale (Parmeliaceae)
Secalonic acid A, a yellow pigment from fungal metabolism, was isolated from the lichens Pseudoparmelia sphaerospora and P. hypomilta. From P. sphaerospora was also isolated the depsidone hypostictic acid. The structure of these compounds was determined by spectroscopic methods and comparison with literature data
Mayall:a framework for desktop JavaScript auditing and post-exploitation analysis
Writing desktop applications in JavaScript offers developers the opportunity to write cross-platform applications with cutting edge capabilities. However in doing so, they are potentially submitting their code to a number of unsanctioned modifications from malicious actors. Electron is one such JavaScript application framework which facilitates this multi-platform out-the-box paradigm and is based upon the Node.js JavaScript runtime --- an increasingly popular server-side technology. In bringing this technology to the client-side environment, previously unrealized risks are exposed to users due to the powerful system programming interface that Node.js exposes. In a concerted effort to highlight previously unexposed risks in these rapidly expanding frameworks, this paper presents the Mayall Framework, an extensible toolkit aimed at JavaScript security auditing and post-exploitation analysis. The paper also exposes fifteen highly popular Electron applications and demonstrates that two thirds of applications were found to be using known vulnerable elements with high CVSS scores. Moreover, this paper discloses a wide-reaching and overlooked vulnerability within the Electron Framework which is a direct byproduct of shipping the runtime unaltered with each application, allowing malicious actors to modify source code and inject covert malware inside verified and signed applications without restriction. Finally, a number of injection vectors are explored and appropriate remediations are proposed
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