13,677 research outputs found
Insulin resistance for glucose metabolism in disused soleus muscle of mice
Results of this study on mice provide the first direct evidence of insulin resistance for glucose metabolism in skeletal muscle that has undergone a previous period of reduced muscle usage. This lack of responsiveness to insulin developed in one day and in the presence of hypoinsulinemia. Future studies will utilize the model of hindlimb immobilization to determine the causes of these changes
Phase Diagrams For The Blue Phases Of Highly Chiral Liquid Crystals
Polarizing microscopy and optical-activity measurements are used to determine the phase diagram for the blue phases of chiral-racemic mixtures of terephthaloyloxy-bis-4-(2\u27-methylbutyl) benzoate. Contrary to an earlier report, it is the second blue phase (BP II) rather than the first blue phase (BP 1) that is not stable relative to the other blue phases at high chirality. With this development, all phase diagrams for the blue phases reported to date have the same topology. Using similar data for two other highly chiral systems, it is found that a simple scaling of the temperature and chiral-fraction axes produces phase diagrams in quantitative agreement with the present results. Thus, in spite of differences in molecular structure, the number of chiral centers, and phase-transition temperatures, these three systems possess remarkably similar phase diagrams and lend evidence for a universal phase diagram for the blue phases
Horizon energy and angular momentum from a Hamiltonian perspective
Classical black holes and event horizons are highly non-local objects,
defined in terms of the causal past of future null infinity. Alternative,
(quasi)local definitions are often used in mathematical, quantum, and numerical
relativity. These include apparent, trapping, isolated, and dynamical horizons,
all of which are closely associated to two-surfaces of zero outward null
expansion. In this paper we show that three-surfaces which can be foliated with
such two-surfaces are suitable boundaries in both a quasilocal action and a
phase space formulation of general relativity. The resulting formalism provides
expressions for the quasilocal energy and angular momentum associated with the
horizon. The values of the energy and angular momentum are in agreement with
those derived from the isolated and dynamical horizon frameworks.Comment: 39 pages, 3 figures, Final Version : content essentially unchanged
but many small improvements made in response to referees, a few references
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Letters between F. M. Booth and W. J. Kerr
Letters concerning a position at the Utah Agricultural College, including recommendations for F. M. Booth and Mrs. F. M. Booth
X-ray Absorption Fine Structure in Embedded Atoms
Oscillatory structure is found in the atomic background absorption in
x-ray-absorption fine structure (XAFS). This atomic-XAFS or AXAFS arises from
scattering within an embedded atom, and is analogous to the Ramsauer-Townsend
effect. Calculations and measurements confirm the existence of AXAFS and show
that it can dominate contributions such as multi-electron excitations. The
structure is sensitive to chemical effects and thus provides a new probe of
bonding and exchange effects on the scattering potential.Comment: 4 pages plus 2 postscript figures, REVTEX 3.
Recommended from our members
Complete Genome Sequence of the Citrobacter freundii Type Strain.
Citrobacter freundii is a species of facultative anaerobic Gram-negative bacteria of the family Enterobacteriaceae The complete genome is composed of a single chromosomal circle of 4,957,773 bp with a G+C content of 52%
Fundamental properties and applications of quasi-local black hole horizons
The traditional description of black holes in terms of event horizons is
inadequate for many physical applications, especially when studying black holes
in non-stationary spacetimes. In these cases, it is often more useful to use
the quasi-local notions of trapped and marginally trapped surfaces, which lead
naturally to the framework of trapping, isolated, and dynamical horizons. This
framework allows us to analyze diverse facets of black holes in a unified
manner and to significantly generalize several results in black hole physics.
It also leads to a number of applications in mathematical general relativity,
numerical relativity, astrophysics, and quantum gravity. In this review, I will
discuss the basic ideas and recent developments in this framework, and
summarize some of its applications with an emphasis on numerical relativity.Comment: 14 pages, 2 figures. Based on a talk presented at the 18th
International Conference on General Relativity and Gravitation, 8-13 July
2007, Sydney, Australi
Enhanced sheath heating in capacitively coupled discharges due to non-sinusoidal voltage waveforms
Through the use of particle-in-cell simulations, we demonstrate that the power deposition in
capacitively coupled discharges (in argon) can be increased by replacing sinusoidal waveforms
with Gaussian-shaped voltage pulses (with a repetition frequency of 13.56 MHz). By changing the
Gaussian pulse width, electron heating can be directly controlled, allowing for an increased plasma
density and ion flux for the same gas pressure and geometrical operating conditions. Analysis
of the power deposition profiles and electron distribution functions shows that enhanced
electron-sheath heating is responsible for the increased power absorption
Sedentary death syndrome is what researchers now call America's second largest threat to public health
Press release.Obesity has doubled, Type 2 diabetes has increased nine-fold, and heart disease remains the number one cause of death for Americans. Sedentary Death Syndrome, or "SeDS," is a growing list of health disorders that are exacerbated by lack of physical activity, causing premature disability and death. Sixty percent of all Americans are at risk, including children. SeDS is expected to add as much as $3 trillion to healthcare costs over ten years, more than twice the tax cut passed by the US Senate
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