18,366 research outputs found
Phase transition of a Bose gas in a harmonic potential
We consider a dilute Bose gas confined by a harmonic potential. We define an
appropriate thermodynamic limit and analyze the properties of the phases and
phase transition in this limit. Critical properties in the presence of the
potential are found to be different from, though simply related, to those in
the usual translationally invariant case. We argue that the properties of
magnetically trapped rubidium\cite{Wieman} and sodium\cite{ketterle} gases (in
which Bose-Einstein condensation has been recently observed) are well
approximated by our thermodynamic limit except in a narrow window of
temperature around the critical temperature. We also consider the effect of the
confining potential on the non-equilibrium dynamics following a rapid quench to
the ordered side and give a scaling description of the late time universal
dynamics.Comment: 10 page
Correlation of high energy muons with primary composition in extensive air shower
An experimental investigation of high energy muons above 200 GeV in extensive air showers has been made for studying high energy interaction and primary composition of cosmic rays of energies in the range 10 to the 14th power approx. 10 to the 15th power eV. The muon energies are estimated from the burst sizes initiated by the muons in the rock, which are measured by four layers of proportional counters, each of area 5 x 2.6 sq m, placed at 30 m.w.e. deep, Funasaka tunnel vertically below the air shower array. These results are compared with Monte Carlo simulations based on the scaling model and the fireball model for two primary compositions, all proton and mixed
Fast Predictive Image Registration
We present a method to predict image deformations based on patch-wise image
appearance. Specifically, we design a patch-based deep encoder-decoder network
which learns the pixel/voxel-wise mapping between image appearance and
registration parameters. Our approach can predict general deformation
parameterizations, however, we focus on the large deformation diffeomorphic
metric mapping (LDDMM) registration model. By predicting the LDDMM
momentum-parameterization we retain the desirable theoretical properties of
LDDMM, while reducing computation time by orders of magnitude: combined with
patch pruning, we achieve a 1500x/66x speed up compared to GPU-based
optimization for 2D/3D image registration. Our approach has better prediction
accuracy than predicting deformation or velocity fields and results in
diffeomorphic transformations. Additionally, we create a Bayesian probabilistic
version of our network, which allows evaluation of deformation field
uncertainty through Monte Carlo sampling using dropout at test time. We show
that deformation uncertainty highlights areas of ambiguous deformations. We
test our method on the OASIS brain image dataset in 2D and 3D
Directed flow as effect of transient matter rotation in hadron and nucleus collisions
We discuss directed flow introduced for description of nucleus collisions and
consider its possible behavior in hadronic and nuclei reactions due to rotation
of the transient matter.Comment: 18 pages, 6 figure
In-situ integrated processing and characterization of thin films of high temperature superconductors, dielectrics and semiconductors by MOCVD
In this strategy of depositing the basic building blocks of superconductors, semiconductors, and dielectric having common elements, researchers deposited superconducting films of Y-Ba-Cu-O, semiconductor films of Cu2O, and dielectric films of BaF2 and Y2O3 by metal oxide chemical vapor deposition (MOCVD). By switching source materials entering the chamber, and by using direct writting capability, complex device structures like three-terminal hybrid semiconductors/superconductors transistors can be fabricated. The Y-Ba-Cu-O superconducting thin films on BaF2/YSZ substrates show a T(sub c) of 80 K and are textured with most of the grains having their c-axis or a-axis perpendicular to the substrate. Electrical characteristics as well as structural characteristics of superconductors and related materials obtained by x-ray defraction, electron microscopy, and energy dispersive x-ray analysis are discussed
In-situ integrated processing and characterization of thin films of high temperature superconductors, dielectrics and semiconductors by MOCVD
In this strategy of depositing the basic building blocks of superconductors, semiconductors, and dielectrics having common elements, researchers deposited superconducting films of Y-Ba-Cu-O, semiconductor films of Cu2O, and dielectric films of BaF2 and Y2O3 by metal oxide chemical vapor deposition (MOCVD). By switching source materials entering the chamber, and by using direct writing capability, complex device structures like three terminal hybrid semiconductor/superconductor transistors can be fabricated. The Y-Ba-Cu-O superconducting thin films on BaF2/YSZ substrates show a T(sub c) of 80 K and are textured with most of the grains having their c-axis or a-axis perpendicular to the substrate. Electrical characteristics as well as structural characteristics of superconductors and related materials obtained by x-ray deffraction, electron microscopy, and energy dispersive x-ray analysis are discussed
A Tunable Anomalous Hall Effect in a Non-Ferromagnetic System
We measure the low-field Hall resistivity of a magnetically-doped
two-dimensional electron gas as a function of temperature and
electrically-gated carrier density. Comparing these results with the carrier
density extracted from Shubnikov-de Haas oscillations reveals an excess Hall
resistivity that increases with decreasing temperature. This excess Hall
resistivity qualitatively tracks the paramagnetic polarization of the sample,
in analogy to the ferromagnetic anomalous Hall effect. The data are consistent
with skew-scattering of carriers by disorder near the crossover to
localization
Disentanglement of two harmonic oscillators in relativistic motion
We study the dynamics of quantum entanglement between two Unruh-DeWitt
detectors, one stationary (Alice), and another uniformly accelerating (Rob),
with no direct interaction but coupled to a common quantum field in (3+1)D
Minkowski space. We find that for all cases studied the initial entanglement
between the detectors disappears in a finite time ("sudden death"). After the
moment of total disentanglement the correlations between the two detectors
remain nonzero until late times. The relation between the disentanglement time
and Rob's proper acceleration is observer dependent. The larger the
acceleration is, the longer the disentanglement time in Alice's coordinate, but
the shorter in Rob's coordinate.Comment: 16 pages, 8 figures; typos added, minor changes in Secs. I and
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