530 research outputs found
Routine Transmission of Elecetroencephalograms by Telephone from a Distant Community
journal articleBiomedical Informatic
A Model for the Telephone Transmission of Six-Channel Electroencephalograms
journal articleBiomedical Informatic
High-speed imaging and wavefront sensing with an infrared avalanche photodiode array
Infrared avalanche photodiode arrays represent a panacea for many branches of
astronomy by enabling extremely low-noise, high-speed and even photon-counting
measurements at near-infrared wavelengths. We recently demonstrated the use of
an early engineering-grade infrared avalanche photodiode array that achieves a
correlated double sampling read noise of 0.73 e- in the lab, and a total noise
of 2.52 e- on sky, and supports simultaneous high-speed imaging and tip-tilt
wavefront sensing with the Robo-AO visible-light laser adaptive optics system
at the Palomar Observatory 1.5-m telescope. We report here on the improved
image quality achieved simultaneously at visible and infrared wavelengths by
using the array as part of an image stabilization control-loop with
adaptive-optics sharpened guide stars. We also discuss a newly enabled survey
of nearby late M-dwarf multiplicity as well as future uses of this technology
in other adaptive optics and high-contrast imaging applications.Comment: Accepted to Astrophysical Journal. 8 pages, 3 figures and 1 tabl
Second generation Robo-AO instruments and systems
The prototype Robo-AO system at the Palomar Observatory 1.5-m telescope is
the world's first fully automated laser adaptive optics instrument. Scientific
operations commenced in June 2012 and more than 12,000 observations have since
been performed at the ~0.12" visible-light diffraction limit. Two new infrared
cameras providing high-speed tip-tilt sensing and a 2' field-of-view will be
integrated in 2014. In addition to a Robo-AO clone for the 2-m IGO and the
natural guide star variant KAPAO at the 1-m Table Mountain telescope, a second
generation of facility-class Robo-AO systems are in development for the 2.2-m
University of Hawai'i and 3-m IRTF telescopes which will provide higher Strehl
ratios, sharper imaging, ~0.07", and correction to {\lambda} = 400 nm.Comment: 11 pages, 4 figures, 3 table
Cyclosporin A protects hepatocytes subjected to high Ca2+ and oxidative stress
AbstractHepatocytes incubated with 0.8 mM t-butylhydroperoxide are protected by cyclosporin A when the medium Ca2+ concentration is 10 mM, but not when it is 2.5 mM. The highest Ca2+ level is associated with an inhibition of t-butylhydroperoxide-dependent malondialdehyde accumulation and with mitochondrial Ca2+ loading within the cells. These findings are new evidence that t-butylhydroperoxide can kill cells by peroxidation-dependent and -independent mechanisms, and suggest that the mitochondrial permeability transition and the resultant de-energization are components of the peroxidation-independent mechanism. Cyclosporin A may have considerable utility for the protection of cells subjected to oxidative stress
Relating Groundwater to Seasonal Wetlands in Southeastern Wisconsin, USA
Historically, drier types of wetlands have been difficult to characterize and are not well researched. Nonetheless, they are considered to reflect the precipitation history with little, if any, regard for possible relation to groundwater. Two seasonal coastal wetland types (wet prairie, sedge meadow) were investigated during three growing seasons at three sites in the Lake Michigan Basin, Wisconsin, USA. The six seasonal wetlands were characterized using standard soil and vegetation techniques and groundwater measurements from the shallow and deep systems. They all met wetland hydrology criteria (e.g., water within 30 cm of land surface for 5% of the growing season) during the early portion of the growing season despite the lack of appreciable regional groundwater discharge into the wetland root zones. Although root-zone duration analyses did not fit a lognormal distribution previously noted in groundwater-dominated wetlands, they were able to discriminate between the plant communities and showed that wet prairie communities had shorter durations of continuous soil saturation than sedge meadow communities. These results demonstrate that the relative rates of groundwater outflows can be important for wetland hydrology and resulting wetland type. Thus, regional stresses to the shallow groundwater system such as pumping or low Great Lake levels can be expected to affect even drier wetland types
Observables and a Hilbert Space for Bianchi IX
We consider a quantization of the Bianchi IX cosmological model based on
taking the constraint to be a self-adjoint operator in an auxiliary Hilbert
space. Using a WKB-style self-consistent approximation, the constraint chosen
is shown to have only continuous spectrum at zero. Nevertheless, the auxiliary
space induces an inner product on the zero-eigenvalue generalized eigenstates
such that the resulting physical Hilbert space has countably infinite
dimension. In addition, a complete set of gauge-invariant operators on the
physical space is constructed by integrating differential forms over the
spacetime. The behavior of these operators indicates that this quantization
preserves Wald's classical result that the Bianchi IX spacetimes expand to a
maximum volume and then recollapse.Comment: 23 pages, ReVTeX, CGPG-94/6-3, UCSBTH-94-3
Purification and properties of an erythrocyte hemoprotein with a unique prosthetic group
1. 1.|A unique hemoprotein has been isolated from a hemolysate of normal human erythrocytes by a procedure which involves (NH4)2SO4 precipitation and chromatography on Amberlite CG-50, DEAE-cellulose, Bio-Gel P-60, and Bio-Gel P-30.2. 2.|The purified hemoprotein appeared homogeneous on ultracentrifugation although small amounts of impurities were detected by polyacrylamide gel electrophoresis. The molecular weight was estimated to be 21 000 by gel filtration. Absorption maxima were located at 416 m[mu] for the oxidized form, 430 m[mu] for the CN- complex of the oxidized form, 434 m[mu] for the reduced form, and 425 m[mu] for the CO derivative of the reduced form. The reduced pyridine hemochrome of the isolated prosthetic group has maxima at 434, 540, and 579 m[mu], clearly indicating that the protein possesses a previously unrecognized heme.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32697/1/0000064.pd
Generalized Sums over Histories for Quantum Gravity I. Smooth Conifolds
This paper proposes to generalize the histories included in Euclidean
functional integrals from manifolds to a more general set of compact
topological spaces. This new set of spaces, called conifolds, includes
nonmanifold stationary points that arise naturally in a semiclasssical
evaluation of such integrals; additionally, it can be proven that sequences of
approximately Einstein manifolds and sequences of approximately Einstein
conifolds both converge to Einstein conifolds. Consequently, generalized
Euclidean functional integrals based on these conifold histories yield
semiclassical amplitudes for sequences of both manifold and conifold histories
that approach a stationary point of the Einstein action. Therefore sums over
conifold histories provide a useful and self-consistent starting point for
further study of topological effects in quantum gravity. Postscript figures
available via anonymous ftp at black-hole.physics.ubc.ca (137.82.43.40) in file
gen1.ps.Comment: 81pp., plain TeX, To appear in Nucl. Phys.
- …