784 research outputs found
Acoustic Spectroscopy of Superfluid 3He in Aerogel
We have designed an experiment to study the role of global anisotropic
quasiparticle scattering on the dirty aerogel superfluid 3He system. We observe
significant regions of two stable phases at temperatures below the superfluid
transition at a pressure of 25 bar for a 98% aerogel.Comment: 2 pages, 2 figures, accepted for publication in proceedings of Low
Temperature Conference 2
Charge metastability and hysteresis in the quantum Hall regime
We report simultaneous quasi-dc magnetotransport and high frequency surface
acoustic wave measurements on bilayer two-dimensional electron systems in GaAs.
Near strong integer quantized Hall states a strong magnetic field sweep
hysteresis in the velocity of the acoustic waves is observed at low
temperatures. This hysteresis indicates the presence of a metastable state with
anomalously high conductivity in the interior of the sample. This
non-equilibrium state is not revealed by conventional low frequency transport
measurements which are dominated by dissipationless transport at the edge of
the 2D system. We find that a field-cooling technique allows the equilibrium
charge configuration within the interior of the sample to be established. A
simple model for this behavior is discussed.Comment: 8 pages, 4 postscript figure
Specific Heat of Disordered He
Porous aerogel is a source of elastic scattering in superfluid 3He and
modifies the properties of the superfluid, suppressing the transition
temperature and order parameter. The specific heat jumps for the B-phase of
superfluid 3He in aerogel have been measured as a function of pressure and
interpreted using the homogeneous and inhomogeneous isotropic scattering
models. The specific heat jumps for other p-wave states are estimated for
comparison.Comment: Manuscript prepared for LT 2
Sudden death due to hemoperitoneum following rupture of cirrhosis-related mesenteric varices
AbstractVarices are caused by increased hemodynamic stress on venous channels due to portal hypertension complicating cirrhosis. Although esophageal varices are the most common site of variceal rupture in cirrhosis, mesenteric variceal rupture causing hemoperitoneum is a rare but fatal complication. There are three similar previously reported cases in the literature. We report a fatal case of hemoperitoneum in a woman caused by spontaneous rupture of mesenteric varices as a result of cirrhosis due to chronic alcoholism. The original site of hemorrhage may remain obscure if the lesion is subtle and overlooked. Therefore a diligent search for mesenteric varices is indicated in all cases with unexplained hemoperitoneum
Anisotropic Aerogels for Studying Superfluid He
It may be possible to stabilize new superfluid phases of He with
anisotropic silica aerogels. We discuss two methods that introduce anisotropy
in the aerogel on length scales relevant to superfluid He. First,
anisotropy can be induced with uniaxial strain. A second method generates
anisotropy during the growth and drying stages. We have grown cylindrical
98% aerogels with anisotropy indicated by preferential radial shrinkage
after supercritical drying and find that this shrinkage correlates with small
angle x-ray scattering (SAXS). The growth-induced anisotropy was found to be
out of phase relative to that induced by strain. This has
implications for the possible stabilization of superfluid phases with specific
symmetry.Comment: 6 pages, 4 figures, submitted to Quantum Fluids and Solids (QFS)
conference 200
Contrasting Information Systems and Financial Executive Perspective on Implementing Regulatory Controls
New corporate compliance regulations such as the Sarbanes Oxley (SOX) Act of 2002 contain requirements for the chief executive and financial officers to certify the effectiveness of internal controls and processes leading to financial reporting. An inevitable result of implementing compliance with these regulations is an increased focus on improving systems and greater interdependence between the financial and IS functions. In this paper, we analyse the data collected on implementation of regulatory compliance and present some new empirical insights on the regulatory control implementation process and consequential changes in the institutional properties of IS and the accounting functions within the organization
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