3,156 research outputs found
Improving Annotations in Digital Documents
Περιέχει το πλήρες κείμενοAnnotation plays a major role in a user’s reading of a document: from
elementary school students making notes on text books to professors marking up
their latest research papers. A common place for annotations to appear is in the
margin of a document. Surprisingly, there is little systematic knowledge of how,
why and when annotations are written in margins or over the main text. This paper
investigates how margin size impacts the ease with which documents can be
annotated, and user annotation behavior. The research comprises of a two part
investigation: first, a paper study that examines margins and their use in physical
documents; secondly, we evaluate document reader software that supports an extended
margin for annotation in digital documents
On the SO(N) symmetry of the chiral SU(N) Yang--Mills model
The posibility of quantizing the anomalous Yang--Mills model
preserving the symmetry under the orthogonal subgroup is indicated. The
corresponding Wess--Zumino action (1-cocycle) possesses the additional
symmetry and can be expressed in terms of chiral fields taking values in the
homogeneous space . The modified anomaly and the constraints
commutator (2-cocycle) are calculated.Comment: 9 pages, preprint PAR-LPTHE 92-48 (DECEMBER 1992), Late
The three-nucleon bound state using realistic potential models
The bound states of H and He have been calculated using the Argonne
plus the Urbana three-nucleon potential. The isospin state
have been included in the calculations as well as the - mass difference.
The H-He mass difference has been evaluated through the charge
dependent terms explicitly included in the two-body potential. The calculations
have been performed using two different methods: the solution of the Faddeev
equations in momentum space and the expansion on the correlated hyperspherical
harmonic basis. The results are in agreement within 0.1% and can be used as
benchmark tests. Results for the CD-Bonn interaction are also presented. It is
shown that the H and He binding energy difference can be predicted
model independently.Comment: 5 pages REVTeX 4, 1 figures, 6 table
Quantum Theory Approach for Neutron Single and Double-Slit Diffraction
We provide a quantum approach description of neutron single and double-slit
diffraction, with specific attention to the cold neutron diffraction (\AA) carried out by Zeilinger et al. in 1988. We find the
theoretical results are good agreement with experimental data.Comment: 10 page
Far-infrared photo-conductivity of electrons in an array of nano-structured antidots
We present far-infrared (FIR) photo-conductivity measurements for a
two-dimensional electron gas in an array of nano-structured antidots. We
detect, resistively and spectrally resolved, both the magnetoplasmon and the
edge-magnetoplasmon modes. Temperature-dependent measurements demonstrates that
both modes contribute to the photo resistance by heating the electron gas via
resonant absorption of the FIR radiation. Influences of spin effect and phonon
bands on the collective excitations in the antidot lattice are observed.Comment: 5 pages, 3 figure
Moving Atom-Field Interaction: Correction to Casimir-Polder Effect from Coherent Back-action
The Casimir-Polder force is an attractive force between a polarizable atom
and a conducting or dielectric boundary. Its original computation was in terms
of the Lamb shift of the atomic ground state in an electromagnetic field (EMF)
modified by boundary conditions along the wall and assuming a stationary atom.
We calculate the corrections to this force due to a moving atom, demanding
maximal preservation of entanglement generated by the moving atom-conducting
wall system. We do this by using non-perturbative path integral techniques
which allow for coherent back-action and thus can treat non-Markovian
processes. We recompute the atom-wall force for a conducting boundary by
allowing the bare atom-EMF ground state to evolve (or self-dress) into the
interacting ground state. We find a clear distinction between the cases of
stationary and adiabatic motions. Our result for the retardation correction for
adiabatic motion is up to twice as much as that computed for stationary atoms.
We give physical interpretations of both the stationary and adiabatic atom-wall
forces in terms of alteration of the virtual photon cloud surrounding the atom
by the wall and the Doppler effect.Comment: 16 pages, 2 figures, clarified discussions; to appear in Phys. Rev.
Relativistic theory of elastic deformable astronomical bodies: perturbation equations in rotating spherical coordinates and junction conditions
In this paper, the dynamical equations and junction conditions at the
interface between adjacent layers of different elastic properties for an
elastic deformable astronomical body in the first post-Newtonian approximation
of Einstein theory of gravity are discussed in both rotating Cartesian
coordinates and rotating spherical coordinates. The unperturbed rotating body
(the ground state) is described as uniformly rotating, stationary and
axisymmetric configuration in an asymptotically flat space-time manifold.
Deviations from the equilibrium configuration are described by means of a
displacement field. In terms of the formalism of relativistic celestial
mechanics developed by Damour, Soffel and Xu, and the framework established by
Carter and Quintana the post Newtonian equations of the displacement field and
the symmetric trace-free shear tensor are obtained. Corresponding
post-Newtonian junction conditions at interfaces also the outer surface
boundary conditions are presented. The PN junction condition is an extension of
Wahr's one which is a Newtonian junction conditions without rotating.Comment: Revtex4, 14 page
Theory of coherent Bragg spectroscopy of a trapped Bose-Einstein condensate
We present a detailed theoretical analysis of Bragg spectroscopy from a
Bose-Einstein condensate at T=0K. We demonstrate that within the linear
response regime, both a quantum field theory treatment and a meanfield
Gross-Pitaevskii treatment lead to the same value for the mean evolution of the
quasiparticle operators. The observable for Bragg spectroscopy experiments,
which is the spectral response function of the momentum transferred to the
condensate, can therefore be calculated in a meanfield formalism. We analyse
the behaviour of this observable by carrying out numerical simulations in
axially symmetric three-dimensional cases and in two dimensions. An approximate
analytic expression for the observable is obtained and provides a means for
identifying the relative importance of three broadening and shift mechanisms
(meanfield, Doppler, and finite pulse duration) in different regimes. We show
that the suppression of scattering at small values of q observed by
Stamper-Kurn et al. [Phys. Rev. Lett. 83, 2876 (1999)] is accounted for by the
meanfield treatment, and can be interpreted in terms of the interference of the
u and v quasiparticle amplitudes. We also show that, contrary to the
assumptions of previous analyses, there is no regime for trapped condensates
for which the spectral response function and the dynamic structure factor are
equivalent. Our numerical calculations can also be performed outside the linear
response regime, and show that at large laser intensities a significant
decrease in the shift of the spectral response function can occur due to
depletion of the initial condensate.Comment: RevTeX4 format, 16 pages plus 7 eps figures; Update to published
version: minors changes and an additional figure. (To appear in Phys. Rev. A
Charge-Symmetry Breaking and the Two-Pion-Exchange Two-Nucleon Interaction
Charge-symmetry breaking in the nucleon-nucleon force is investigated within
an effective field theory, using a classification of isospin-violating
interactions based on power-counting arguments. The relevant
charge-symmetry-breaking interactions corresponding to the first two orders in
the power counting are discussed, including their effects on the 3He-3H
binding-energy difference. The static charge-symmetry-breaking potential linear
in the nucleon-mass difference is constructed using chiral perturbation theory.
Explicit formulae in momentum and configuration spaces are presented. The
present work completes previously obtained results.Comment: 15 pages, 2 figure
Fermi surface instabilities at finite Temperature
We present a new method to detect Fermi surface instabilities for interacting
systems at finite temperature. We first apply it to a list of cases studied
previously, recovering already known results in a very economic way, and
obtaining most of the information on the phase diagram analytically. As an
example, in the continuum limit we obtain the critical temperature as an
implicit function of the magnetic field and the chemical potential
. By applying the method to a model proposed to describe reentrant
behavior in , we reproduce the phase diagram obtained
experimentally and show the presence of a non-Fermi Liquid region at
temperatures above the nematic phase.Comment: 10 pages, 10 figure
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