10,093 research outputs found
Scalar-tensor cosmological simulations
We present -body cosmlogical simulations in the framework of the Newtonian
limit of scalar-tensor theories of gravity. The scalar field is described by a
modified Helmholtz equation with a source that is coupled to the standard
Poisson equation of Newtonian gravity. The effective gravitational force is
given by two contributions: the standard Newtonian potential plus a Yukawa
potential stemming from massive scalar fields. In particular, we consider
simulations of CDM models and compute the density and velocity
profiles of the most massive groups found at z=0.Comment: 6 pages, 6 figures. Recent Developments in Gravitation and
Experimental Physics: 3rd Mexican Meeting of Mathematical and Experimental
Physics. Edited by A. Macias, C. Laemmerzahl, and A. Camacho. (American
Institute of Physics, 2008). Pag. 30
From vertex detectors to inner trackers with CMOS pixel sensors
The use of CMOS Pixel Sensors (CPS) for high resolution and low material
vertex detectors has been validated with the 2014 and 2015 physics runs of the
STAR-PXL detector at RHIC/BNL. This opens the door to the use of CPS for inner
tracking devices, with 10-100 times larger sensitive area, which require
therefore a sensor design privileging power saving, response uniformity and
robustness. The 350 nm CMOS technology used for the STAR-PXL sensors was
considered as too poorly suited to upcoming applications like the upgraded
ALICE Inner Tracking System (ITS), which requires sensors with one order of
magnitude improvement on readout speed and improved radiation tolerance. This
triggered the exploration of a deeper sub-micron CMOS technology, Tower-Jazz
180 nm, for the design of a CPS well adapted for the new ALICE-ITS running
conditions. This paper reports the R&D results for the conception of a CPS well
adapted for the ALICE-ITS.Comment: 4 pages, 4 figures, VCI 2016 conference proceeding
Reducing numerical diffusion for incompressible flow calculations
A number of approaches for improving the accuracy of incompressible, steady-state flow calculations are examined. Two improved differencing schemes, Quadratic Upstream Interpolation for Convective Kinematics (QUICK) and Skew-Upwind Differencing (SUD), are applied to the convective terms in the Navier-Stokes equations and compared with results obtained using hybrid differencing. In a number of test calculations, it is illustrated that no single scheme exhibits superior performance for all flow situations. However, both SUD and QUICK are shown to be generally more accurate than hybrid differencing
The Ingalls-Thomas Bijections
Given a finite acyclic quiver Q with path algebra kQ, Ingalls and Thomas have
exhibited a bijection between the set of Morita equivalence classes of
support-tilting modules and the set of thick subcategories of mod kQ and they
have collected a large number of further bijections with these sets. We add
some additional bijections and show that all these bijections hold for
arbitrary hereditary artin algebras. The proofs presented here seem to be of
interest also in the special case of the path algebra of a quiver.Comment: This is a modified version of an appendix which was written for the
paper "The numbers of support-tilting modules for a Dynkin algebra" (see
arXiv:1403.5827v1
Micro-device for coupling, multiplexing and demultiplexing using elliptical-core two-mode fiber
We propose and demonstrate experimentally a fiber optic micro-device that is capable of tunably splitting, multiplexing, and demultiplexing optical signals using elliptical-core two-mode optical fiber. A crosstalk of 15 dB with an insertion loss of 1.2 dB was obtained
Ultrafast dynamics of a magnetic antivortex - Micromagnetic simulations
The antivortex is a fundamental magnetization structure which is the
topological counterpart of the well-known magnetic vortex. We study here the
ultrafast dynamic behavior of an isolated antivortex in a patterned Permalloy
thin-film element. Using micromagnetic simulations we predict that the
antivortex response to an ultrashort external field pulse is characterized by
the production of a new antivortex as well as of a temporary vortex, followed
by an annihilation process. These processes are complementary to the recently
reported response of a vortex and, like for the vortex, lead to the reversal of
the orientation of the antivortex core region. In addition to its fundamental
interest, this dynamic magnetization process could be used for the generation
and propagation of spin waves for novel logical circuits.Comment: 4 pages, 4 figures. To be published in Physical Review B (R
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