2,722 research outputs found
Effect of C. parvum and active specific immunotherapy on intracerebral transplants of a murine fibrosarcoma.
Dual Geometric Worm Algorithm for Two-Dimensional Discrete Classical Lattice Models
We present a dual geometrical worm algorithm for two-dimensional Ising
models. The existence of such dual algorithms was first pointed out by
Prokof'ev and Svistunov \cite{ProkofevClassical}. The algorithm is defined on
the dual lattice and is formulated in terms of bond-variables and can therefore
be generalized to other two-dimensional models that can be formulated in terms
of bond-variables. We also discuss two related algorithms formulated on the
direct lattice, applicable in any dimension. These latter algorithms turn out
to be less efficient but of considerable intrinsic interest. We show how such
algorithms quite generally can be "directed" by minimizing the probability for
the worms to erase themselves. Explicit proofs of detailed balance are given
for all the algorithms. In terms of computational efficiency the dual
geometrical worm algorithm is comparable to well known cluster algorithms such
as the Swendsen-Wang and Wolff algorithms, however, it is quite different in
structure and allows for a very simple and efficient implementation. The dual
algorithm also allows for a very elegant way of calculating the domain wall
free energy.Comment: 12 pages, 6 figures, Revtex
Dissipative Transport of a Bose-Einstein Condensate
We investigate the effects of impurities, either correlated disorder or a
single Gaussian defect, on the collective dipole motion of a Bose-Einstein
condensate of Li in an optical trap. We find that this motion is damped at
a rate dependent on the impurity strength, condensate center-of-mass velocity,
and interatomic interactions. Damping in the Thomas-Fermi regime depends
universally on the disordered potential strength scaled to the condensate
chemical potential and the condensate velocity scaled to the peak speed of
sound. The damping rate is comparatively small in the weakly interacting
regime, and the damping in this case is accompanied by strong condensate
fragmentation. \textit{In situ} and time-of-flight images of the atomic cloud
provide evidence that this fragmentation is driven by dark soliton formation.Comment: 14 pages, 20 figure
(5S,6R)-5-Methyl-6-phenyl-4-propyl-1,3,4-oxadiazinane-2-thione
The title molecule, C13H18N2OS, is an oxadiazinanthione derived from (1R,2S)-norephedrine. There are two molecules in the asymmetric. Both adopt roughly half-chair conformations; however, the 5-position carbon orients out of opposite faces of the oxadiazinanthiones plane in the two molecules. In the crystal structure, they are oriented as a dimer linked by a pair of N—H⋯S hydrogen bonds. The absolute configuration has been established from anomalous dispersion and confirms the known stereochemistry based on the synthetic procedure
(5R,6S)-4-Isopropyl-5-methyl-6-phenyl-3-propanoyl-2H-1,3,4-oxadiazinan-2-one
The title compound, C16H22N2O3, was synthesized during the course of a study on (1R,2S)-norephedrine-derived 1,3,4-oxadiazinan-2-ones. The conformation adopted by the isopropyl group is pseudo-axial relative to the oxadiazinan core. The allylic strain contributes to this conformational arrangement
Experimental detection of entanglement via witness operators and local measurements
In this paper we address the problem of detection of entanglement using only
few local measurements when some knowledge about the state is given. The idea
is based on an optimized decomposition of witness operators into local
operators. We discuss two possible ways of optimizing this local decomposition.
We present several analytical results and estimates for optimized detection
strategies for NPT states of 2x2 and NxM systems, entangled states in 3 qubit
systems, and bound entangled states in 3x3 and 2x4 systems.Comment: 24 pages, 2 figures. Contribution to the proceedings of the
International Conference on Quantum Information in Oviedo, Spain (July 13-18,
2002). Error in W_W1-witness Eq. (35) corrected as well as minor typos.
Reference adde
First principles theory of chiral dichroism in electron microscopy applied to 3d ferromagnets
Recently it was demonstrated (Schattschneider et al., Nature 441 (2006),
486), that an analogue of the X-ray magnetic circular dichroism (XMCD)
experiment can be performed with the transmission electron microscope (TEM).
The new phenomenon has been named energy-loss magnetic chiral dichroism (EMCD).
In this work we present a detailed ab initio study of the chiral dichroism in
the Fe, Co and Ni transition elements. We discuss the methods used for the
simulations together with the validity and accuracy of the treatment, which
can, in principle, apply to any given crystalline specimen. The dependence of
the dichroic signal on the sample thickness, accuracy of the detector position
and the size of convergence and collection angles is calculated.Comment: 9 pages, 6 figures, submitted to Physical Review
Dinosaur tracks from the Kilmaluag Formation (Bathonian, Middle Jurassic) of Score Bay, Isle of Skye, Scotland, UK
Tracks of a juvenile theropod dinosaur with footprint lengths of between 2 and 9 cm as well as adults of the same ichnospecies with footprints of about 15–25 cm in length were found in the Bathonian (Middle Jurassic) Kilmaluag Formation of Score Bay, northwestern Trotternish Peninsula, Isle of Skye, Scotland, UK. Two footprint sizes occur together on the same bedding plane in the central portion of Score Bay, both in situ and on loose blocks. Another horizon containing footprints above this was also identified. The footprints from the lowest horizon were produced in a desiccated silty mud that was covered with sand. A close association of both adults and juveniles with similar travel direction indicated by the footprints may suggest post-hatching care in theropod dinosaurs. Other footprints, produced on a rippled sandy substrate, have been found on the slightly higher bedding plane at this locality. Loose blocks found 130 m to the northeast in the central part of Score Bay have not been correlated with any in situ sediments, but were preserved in a similar manner to those from the higher bedding plane. These tracks represent the youngest dinosaur remains yet found in Scotland
Acoustic-to-Articulatory Speech Inversion Features for Mispronunciation Detection of /r/ in Child Speech Sound Disorders
Acoustic-to-articulatory speech inversion could enhance automated clinical
mispronunciation detection to provide detailed articulatory feedback
unattainable by formant-based mispronunciation detection algorithms; however,
it is unclear the extent to which a speech inversion system trained on adult
speech performs in the context of (1) child and (2) clinical speech. In the
absence of an articulatory dataset in children with rhotic speech sound
disorders, we show that classifiers trained on tract variables from
acoustic-to-articulatory speech inversion meet or exceed the performance of
state-of-the-art features when predicting clinician judgment of rhoticity.
Index Terms: rhotic, speech sound disorder, mispronunciation detectionComment: *denotes equal contribution. To appear in Proceedings of the Annual
Conference of the International Speech Communication Association, INTERSPEECH
202
Strain Relaxation Mechanisms and Local Structural Changes in Si_{1-x}$Ge_{x} Alloys
In this work, we address issues pertinent to the understanding of the
structural and electronic properties of Si_{1-x} Ge_{x}alloys, namely, (i) how
does the lattice constant mismatch between bulk Si and bulk Ge manifests itself
in the alloy system? and (ii) what are the relevant strain release mechanisms?
To provide answers to these questions, we have carried out an in-depth study of
the changes in the local geometric and electronic structures arising from the
strain relaxation in Si_{1-x} Ge_{x} alloys using an ab initio molecular
dynamics scheme. The optimized lattice constant, while exhibiting a general
trend of linear dependence on the composition (Vegard's law), shows a negative
deviation from Vegard's law in the vicinity of x=0.5. We delineate the
mechanisms responsible for each one of the above features. We show that the
radial-strain relaxation through bond stretching is responsible for the overall
trend of linear dependence of the lattice constant on the composition. On the
other hand, the negative deviation from Vegard's law is shown to arise from the
angular-strain relaxation.Comment: 21 pages, 7 figure
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