57,822 research outputs found
Invariant measures for monotone SPDE's with multiplicative noise term
We study diffusion processes corresponding to infinite dimensional semilinear
stochastic differential equations with local Lipschitz drift term and an
arbitrary Lipschitz diffusion coefficient. We prove tightness and the Feller
property of the solution to show existence of an invariant measure. As an
application we discuss stochastic reaction diffusion equations.Comment: 10 page
Yang-Yang thermodynamics on an atom chip
We investigate the behavior of a weakly interacting nearly one-dimensional
(1D) trapped Bose gas at finite temperature. We perform in situ measurements of
spatial density profiles and show that they are very well described by a model
based on exact solutions obtained using the Yang-Yang thermodynamic formalism,
in a regime where other, approximate theoretical approaches fail. We use
Bose-gas focusing [Shvarchuck etal., Phys. Rev. Lett. 89, 270404 (2002)] to
probe the axial momentum distribution of the gas, and find good agreement with
the in situ results.Comment: extended introduction and conclusions, and minor changes throughout;
accepted for publication in Phys. Rev. Let
Initial results of finger imaging using Photoacoustic Computed Tomography
We present a photoacoustic computed tomography investigation on a healthy
human finger, to image blood vessels with a focus on vascularity across the
interphalangeal joints. The cross-sectional images were acquired using an
imager specifically developed for this purpose. The images show rich detail of
the digital blood vessels with diameters between 100 m and 1.5 mm in
various orientations and at various depths. Different vascular layers in the
skin including the subpapillary plexus could also be visualized. Acoustic
reflections on the finger bone of photoacoustic signals from skin were visible
in sequential slice images along the finger except at the location of the joint
gaps. Not unexpectedly, the healthy synovial membrane at the joint gaps was not
detected due to its small size and normal vascularization. Future research will
concentrate on studying digits afflicted with rheumatoid arthritis to detect
the inflamed synovium with its heightened vascularization, whose
characteristics are potential markers for disease activity.Comment: 2 figure
Box traps on an atom chip for one-dimensional quantum gases
We present the implementation of tailored trapping potentials for ultracold
gases on an atom chip. We realize highly elongated traps with box-like
confinement along the long, axial direction combined with conventional harmonic
confinement along the two radial directions. The design, fabrication and
characterization of the atom chip and the box traps is described. We load
ultracold (K) clouds of Rb in a box trap, and demonstrate
Bose-gas focusing as a means to characterize these atomic clouds in arbitrarily
shaped potentials. Our results show that box-like axial potentials on atom
chips are very promising for studies of one-dimensional quantum gases.Comment: 9 pages 4 figure
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