111 research outputs found
Progressive internal gravity waves with bounded upper surface climbing a triangular obstacle
In this paper we discuss a theoretical model for the interfacial profiles of
progressive non-linear waves which result from introducing a triangular
obstacle, of finite height, attached to the bottom below the flow of a
stratified, ideal, two layer fluid, bounded from above by a rigid boundary. The
derived equations are solved by using a nonlinear perturbation method. The
dependence of the interfacial profile on the triangular obstacle size, as well
as its dependence on some flow parameters, such as the ratios of depths and
densities of the two fluids, have been studied
Quantum Error Correction via Convex Optimization
We show that the problem of designing a quantum information error correcting
procedure can be cast as a bi-convex optimization problem, iterating between
encoding and recovery, each being a semidefinite program. For a given encoding
operator the problem is convex in the recovery operator. For a given method of
recovery, the problem is convex in the encoding scheme. This allows us to
derive new codes that are locally optimal. We present examples of such codes
that can handle errors which are too strong for codes derived by analogy to
classical error correction techniques.Comment: 16 page
The double Caldeira-Leggett model: Derivation and solutions of the master equations, reservoir-induced interactions and decoherence
In this paper we analyze the double Caldeira-Leggett model: the path integral
approach to two interacting dissipative harmonic oscillators. Assuming a
general form of the interaction between the oscillators, we consider two
different situations: i) when each oscillator is coupled to its own reservoir,
and ii) when both oscillators are coupled to a common reservoir. After deriving
and solving the master equation for each case, we analyze the decoherence
process of particular entanglements in the positional space of both
oscillators. To analyze the decoherence mechanism we have derived a general
decay function for the off-diagonal peaks of the density matrix, which applies
both to a common and separate reservoirs. We have also identified the expected
interaction between the two dissipative oscillators induced by their common
reservoir. Such reservoir-induced interaction, which gives rise to interesting
collective damping effects, such as the emergence of relaxation- and
decoherence-free subspaces, is shown to be blurred by the high-temperature
regime considered in this study. However, we find that different interactions
between the dissipative oscillators, described by rotating or counter-rotating
terms, result in different decay rates for the interference terms of the
density matrix.Comment: 42 pages, 7 figures, new discussion added, typos adde
Defining lesional, perilesional and unaffected skin in hidradenitis suppurativa: proposed recommendations for clinical trials and translational research studies
Hidradenitis suppurativa (HS) is a chronic, recurring inflammatory skin condition for which the pathogenesis is not completely elucidated1. With the increase in HSârelated research comes the need to enhance reproducibility, quality and accuracy of scientific methods. Unlike other inflammatory dermatoses such as psoriasis or atopic dermatitis, HS lesions are morphologically diverse and include nodules, abscesses, tunnels and fibrosis in various permutations and combinations admixed in the same anatomical region1. This makes general definitions as âlesionalâ and ânonâlesionalâ insufficient for HSârelated investigations. A definition for nonâlesional skin is lacking
A theoretical and empirical investigation of nutritional label use
Due in part to increasing diet-related health problems caused, among others, by obesity, nutritional labelling has been considered important, mainly because it can provide consumers with information that can be used to make informed and healthier food choices. Several studies have focused on the empirical perspective of nutritional label use. None of these studies, however, have focused on developing a theoretical economic model that would adequately describe nutritional label use based on a utility theoretic framework. We attempt to fill this void by developing a simple theoretical model of nutritional label use, incorporating the time a consumer spends reading labels as part of the food choice process. The demand equations of the model are then empirically tested. Results suggest the significant role of several variables that flow directly from the model which, to our knowledge, have not been used in any previous empirical work
Neutronic Design and Measured Performance of the Low Energy Neutron Source (LENS) Target Moderator Reflector Assembly
The Low Energy Neutron Source (LENS) is an accelerator-based pulsed cold
neutron facility under construction at the Indiana University Cyclotron
Facility (IUCF). The idea behind LENS is to produce pulsed cold neutron beams
starting with ~MeV neutrons from (p,n) reactions in Be which are moderated to
meV energies and extracted from a small solid angle for use in neutron
instruments which can operate efficiently with relatively broad (~1 msec)
neutron pulse widths. Although the combination of the features and operating
parameters of this source is unique at present, the neutronic design possesses
several features similar to those envisioned for future neutron facilities such
as long-pulsed spallation sources (LPSS) and very cold neutron (VCN) sources.
We describe the underlying ideas and design details of the
target/moderator/reflector system (TMR) and compare measurements of its
brightness, energy spectrum, and emission time distribution under different
moderator configurations with MCNP simulations. Brightness measurements using
an ambient temperature water moderator agree with MCNP simulations within the
20% accuracy of the measurement. The measured neutron emission time
distribution from a solid methane moderator is in agreement with simulation and
the cold neutron flux is sufficient for neutron scattering studies of
materials. We describe some possible modifications to the existing design which
would increase the cold neutron brightness with negligible effect on the
emission time distribution.Comment: This is a preprint version of an article which has been published in
Nuclear Instruments and Methods in Physics Research A 587 (2008) 324-341.
http://dx.doi.org/10.1016/j.nima.2007.12.04
Near-IR Atlas of S0-Sa galaxies (NIRS0S)
An atlas of Ks-band images of 206 early-type galaxies is presented, including
160 S0-S0/a galaxies, 12 ellipticals, and 33 Sa galaxies. A majority of the
Atlas galaxies belong to a magnitude-limited (mB<12.5 mag) sample of 185 NIRS0S
(Near-IR S0 galaxy Survey) galaxies. To assure that mis-classified S0s are not
omitted, 25 ellipticals from RC3 classified as S0s in the Carnegie Atlas were
included in the sample. The images are 2-3 mag deeper than 2MASS images. Both
visual and photometric classifications are made. Special attention is paid to
the classification of lenses, coded in a systematic manner. A new lens-type,
called a 'barlens', is introduced. Also, boxy/peanut/x-shaped structures are
identified in many barred galaxies, even-though the galaxies are not seen in
edge-on view, indicating that vertical thickening is not enough to explain
them. Multiple lenses appear in 25% of the Atlas galaxies, which is a challenge
to the hierarchical evolutionary picture of galaxies. Such models need to
explain how the lenses were formed and survived in multiple merger events that
galaxies may have suffered during their lifetimes. Following the early
suggestion by van den Bergh, candidates of S0c galaxies are shown, which
galaxies are expected to be former Sc-type spirals stripped out of gas.Comment: 67 pages (include 16 figures and 6 tables). Accepted to MNRAS 2011
June 1
Special Libraries, April 1933
Volume 24, Issue 3https://scholarworks.sjsu.edu/sla_sl_1933/1002/thumbnail.jp
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