34,139 research outputs found
Cylindrical Invisibility Cloak with Simplified Material Parameters is Inherently Visible
It was proposed that perfect invisibility cloaks can be constructed for
hiding objects from electromagnetic illumination (Pendry et al., Science 312,
p. 1780). The cylindrical cloaks experimentally demonstrated (Schurig et al.,
Science 314, p. 997) and proposed (Cai et al., Nat. Photon. 1, p. 224) have
however simplified material parameters in order to facilitate easier
realization as well as to avoid infinities in optical constants. Here we show
that the cylindrical cloaks with simplified material parameters inherently
allow the zeroth-order cylindrical wave to pass through the cloak as if the
cloak is made of a homogeneous isotropic medium, and thus visible. To all
high-order cylindrical waves, our numerical simulation suggests that the
simplified cloak inherits some properties of the ideal cloak, but finite
scatterings exist.Comment: 10 pages, 3 figure
Sub-barrier Coulomb effects on the interference pattern in tunneling ionization photoelectron spectra
We use a quantum trajectory-based semi-classical method to account for
Coulomb interaction between the photoelectron and the parent ion in the
classically forbidden, sub-barrier region during strong-field tunneling
ionization processes. We show that---besides the well-known modification of the
tunneling ionization probability---there is also an influence on the
interference pattern in the photoelectron spectra. In the long-wavelength
limit, the shift of the intra-cycle interference fringes caused by sub-barrier
Coulomb effects in the laser polarization direction can be derived
analytically. We compare our results with \emph{ab initio} solutions of the
time-dependent Schr\"odinger equation and find good agreement in the
long-wavelength regime, whereas the standard strong field approximation fails.
We show that the nodal structure along low-order above-threshold ionization
rings is also affected by sub-barrier Coulomb effects.Comment: 10 pages, 4 figures, RevTe
Wilson lines and UV sensitivity in magnetic compactifications
We investigate the ultraviolet (UV) behaviour of 6D N=1 supersymmetric
effective (Abelian) gauge theories compactified on a two-torus () with
magnetic flux. To this purpose we compute offshell the one-loop correction to
the Wilson line state self-energy. The offshell calculation is actually
necessary to capture the usual effective field theory expansion in powers of
. Particular care is paid to the regularization of the
(divergent) momentum integrals, which is relevant for identifying the
corresponding counterterm(s). We find a counterterm which is a new higher
dimensional effective operator of dimension d=6, that is enhanced for a larger
compactification area (where the effective theory applies) and is consistent
with the symmetries of the theory. Its consequences are briefly discussed and
comparison is made with orbifold compactifications without flux.Comment: 12 pages, 1 figure; (v2: added references and paragraph on page 7
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Computer-aided programming for multiprocessing systems
As both the number of processors and the complexity of problems to be solved increase, programming multiprocessing systems becomes more difficult and error-prone. This report discusses parallel models of computation and tools for computer-aided programming (CAP). Program development tools are necessary since programmers are not able to develop complex parallel programs efficiently. In particular, a CAP tool, named Hypertool, is described here. It performs scheduling and handles the communication primitive insertion automatically so that many errors are eliminated. It also generates the performance estimates and other program quality measures to help programmers in improving their algorithms and programs. Experiments have shown that up to a 300% performance improvement can be achieved by computer-aided programming
The Inuence of Misspecified Covariance on False Discovery Control when Using Posterior Probabilities
This paper focuses on the influence of a misspecified covariance structure on
false discovery rate for the large scale multiple testing problem.
Specifically, we evaluate the influence on the marginal distribution of local
fdr statistics, which are used in many multiple testing procedures and related
to Bayesian posterior probabilities. Explicit forms of the marginal
distributions under both correctly specified and incorrectly specified models
are derived. The Kullback-Leibler divergence is used to quantify the influence
caused by a misspecification. Several numerical examples are provided to
illustrate the influence. A real spatio-temporal data on soil humidity is
discussed.Comment: 22 pages, 5 figure
Exactly Solvable Model for Helix-Coil-Sheet Transitions in Protein Systems
In view of the important role helix-sheet transitions play in protein
aggregation, we introduce a simple model to study secondary structural
transitions of helix-coil-sheet systems using a Potts model starting with an
effective Hamiltonian. This energy function depends on four parameters that
approximately describe entropic and enthalpic contributions to the stability of
a polypeptide in helical and sheet conformations. The sheet structures involve
long-range interactions between residues which are far in sequence, but are in
contact in real space. Such contacts are included in the Hamiltonian. Using
standard statistical mechanical techniques, the partition function is solved
exactly using transfer matrices. Based on this model, we study thermodynamic
properties of polypeptides, including phase transitions between helix, sheet,
and coil structures.Comment: Updated version with correction
Early Delirium Assessment for Hospitalized Older People in Indonesia: a Systematic Review
Background: Due to the increasing risk of getting co-morbidity and frailty, older people tend to be prone to hospitalization. Hospitalization in older people brings many adverse effects. Moreover, when these elderly get delirium, the mortality and morbidity will increase. The risk of getting deterioration and worsening condition because of delirium would also increase. In fact, delirium assessment is not a high priority in taking care older people during hospitalization because the focus of care is treating the disease.Delirium screening as an early recognition of delirium in the hospitalized elderly inIndonesia remains unreported and even do not well evaluated. Therefore, delirium as a preventable problem or causing problems remains unrecognized.Purpose: This paper aims to review the current evidence of early assessment of delirium in hospitalized older people.Methods: A systematic review was conducted from four databases yielding to 4 articles which met the inclusion and exclusion criteria.Results: There are four focuses on the result, namely delirium screening tools, patient characteristics, identified early delirium assessment, and outcomes affected by early delirium assessment. Confusion Assessment Method (CAM) was used as the delirium screening tool in the hospital. Establishing the care team involving many disciplines will give a better way to improve the integrated care and collaborative care.Conclusion: Performing CAM integrated into comprehensive geriatric assessment can be the most important thing to be undertaken when looking after the hospitalized elderly
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