18,264 research outputs found
Preparation of a geologic photo map and hydrologic study of the Yemen Arab Republic
There are no author-identified significant results in this report
The generalized Fenyes-Nelson model for free scalar field theory
The generalized Fenyes--Nelson model of quantum mechanics is applied to the
free scalar field. The resulting Markov field is equivalent to the Euclidean
Markov field with the times scaled by a common factor which depends on the
diffusion parameter. This result is consistent between Guerra's earlier work on
stochastic quantization of scalar fields. It suggests a deep connection between
Euclidean field theory and the stochastic interpretation of quantum mechanics.
The question of Lorentz covariance is also discussed.Comment: 6 page
On rigidly rotating perfect fluid cylinders
The gravitational field of a rigidly rotating perfect fluid cylinder with
gamma- law equation of state is found analytically. The solution has two
parameters and is physically realistic for gamma in the interval (1.41,2].
Closed timelike curves always appear at large distances.Comment: 10 pages, Revtex (galley
Photoionization and Photoelectric Loading of Barium Ion Traps
Simple and effective techniques for loading barium ions into linear Paul
traps are demonstrated. Two-step photoionization of neutral barium is achieved
using a weak intercombination line (6s2 1S0 6s6p 3P1, 791 nm) followed by
excitation above the ionization threshold using a nitrogen gas laser (337 nm).
Isotopic selectivity is achieved by using a near Doppler-free geometry for
excitation of the triplet 6s6p 3P1 state. Additionally, we report a
particularly simple and efficient trap loading technique that employs an
in-expensive UV epoxy curing lamp to generate photoelectrons.Comment: 5 pages, Accepted to PRA 3/20/2007 -fixed typo -clarified figure 3
caption -added reference [15
A Memory Bandwidth-Efficient Hybrid Radix Sort on GPUs
Sorting is at the core of many database operations, such as index creation,
sort-merge joins, and user-requested output sorting. As GPUs are emerging as a
promising platform to accelerate various operations, sorting on GPUs becomes a
viable endeavour. Over the past few years, several improvements have been
proposed for sorting on GPUs, leading to the first radix sort implementations
that achieve a sorting rate of over one billion 32-bit keys per second. Yet,
state-of-the-art approaches are heavily memory bandwidth-bound, as they require
substantially more memory transfers than their CPU-based counterparts.
Our work proposes a novel approach that almost halves the amount of memory
transfers and, therefore, considerably lifts the memory bandwidth limitation.
Being able to sort two gigabytes of eight-byte records in as little as 50
milliseconds, our approach achieves a 2.32-fold improvement over the
state-of-the-art GPU-based radix sort for uniform distributions, sustaining a
minimum speed-up of no less than a factor of 1.66 for skewed distributions.
To address inputs that either do not reside on the GPU or exceed the
available device memory, we build on our efficient GPU sorting approach with a
pipelined heterogeneous sorting algorithm that mitigates the overhead
associated with PCIe data transfers. Comparing the end-to-end sorting
performance to the state-of-the-art CPU-based radix sort running 16 threads,
our heterogeneous approach achieves a 2.06-fold and a 1.53-fold improvement for
sorting 64 GB key-value pairs with a skewed and a uniform distribution,
respectively.Comment: 16 pages, accepted at SIGMOD 201
Exactly separable version of the Bohr Hamiltonian with the Davidson potential
An exactly separable version of the Bohr Hamiltonian is developed using a
potential of the form u(beta)+u(gamma)/beta^2, with the Davidson potential
u(beta)= beta^2 + beta_0^4/beta^2 (where beta_0 is the position of the minimum)
and a stiff harmonic oscillator for u(gamma) centered at gamma=0. In the
resulting solution, called exactly separable Davidson (ES-D), the ground state
band, gamma band and 0_2^+ band are all treated on an equal footing. The
bandheads, energy spacings within bands, and a number of interband and
intraband B(E2) transition rates are well reproduced for almost all
well-deformed rare earth and actinide nuclei using two parameters (beta_0,
gamma stiffness). Insights regarding the recently found correlation between
gamma stiffness and the gamma-bandhead energy, as well as the long standing
problem of producing a level scheme with Interacting Boson Approximation SU(3)
degeneracies from the Bohr Hamiltonian, are also obtained.Comment: 35 pages, 11 postscript figures, LaTe
About the dynamics and thermodynamics of trapped ions
This tutorial introduces the dynamics of charged particles in a
radiofrequency trap in a very general manner to point out the differences
between the dynamics in a quadrupole and in a multipole trap. When dense
samples are trapped, the dynamics is modified by the Coulomb repulsion between
ions. To take into account this repulsion, we propose to use a method,
originally developed for particles in Penning trap, that model the ion cloud as
a cold fluid. This method can not reproduce the organisation of cold clouds as
crystals but it allows one to scale the size of large samples with the trapping
parameters and the number of ions trapped, for different linear geometries of
trap.Comment: accepted for publication in the "Modern Applications of Trapped Ions"
special issu
Vector meson spectral function and dilepton rate in an effective mean field model
We have studied the vector meson spectral function (VMSF) in a hot and dense
medium within an effective QCD model namely the Nambu-Jona-Lasinio (NJL) and
its Polyakov Loop extended version (PNJL) with and without the effect of
isoscalar vector interaction (IVI). The effect of the IVI has been taken into
account using the ring approximation. We obtained the dilepton production rate
(DPR) using the VMSF and observed that at moderate temperature it is enhanced
in the PNJL model as compared to the NJL and Born rate due to the suppression
of color degrees of freedom.Comment: 5 pages, 7 figures, conference proceedings of the XXI DAE-BRNS HEP
Symposium, IIT Guwahati, December 2014; to appear in 'Springer Proceedings in
Physics Series
Unitary ambiguity in the extraction of the E2/M1 ratio for the transition
The resonant electric quadrupole amplitude in the transition is of great interest for the understanding of
baryon structure. Various dynamical models have been developed to extract it
from the corresponding photoproduction multipole of pions on nucleons. It is
shown that once such a model is specified, a whole class of unitarily
equivalent models can be constructed, all of them providing exactly the same
fit to the experimental data. However, they may predict quite different
resonant amplitudes. Therefore, the extraction of the E2/M1() ratio (bare or dressed) which is based on a dynamical
model using a largely phenomenological interaction is not unique.Comment: 10 pages revtex including 4 postscript figure
Preparation of a geologic photo map and hydrologic study of the Yemen Arab Republic
There are no author-identified significant results in this report
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