8,187 research outputs found
Music in George Eliot\u27s Life and Works
In the following thesis the author has attempted to show the importance of music to George Eliot personally, and her response to it as portrayed by the various characters in her books. In this study it was necessary to point out the various phases of music with which George Eliot was familiar and the interesting way in which she incorporated them in her stories
Aspects of brane-antibrane inflation
I describe a dynamical mechanism for solving the fine-tuning problem of
brane-antibrane inflation. By inflating with stacks of branes and antibranes,
the branes can naturally be trapped at a metastable minimum of the potential.
As branes tunnel out of this minimum, the shape of the potential changes to
make the minimum shallower. Eventually the minimum disappears and the remaining
branes roll slowly because the potential is nearly flat. I show that even with
a small number of branes, there is a good chance of getting enough inflation.
Running of the spectral index is correlated with the tilt in such a way as to
provide a test of the model by future CMB experiments.Comment: 6 pages, 5 figures; proceedings of Theory Canada 1 conference, 2-5
June 2005, UBC, Vancouve
No new limit on the size distribution of gamma-ray bursts
The results of a study (Carter et. al.) of gamma ray bursts using long duration balloon exposure are analyzed. Arguments are presented against the conclusion that the size spectrum extrapolates to a power law with index from -1.0 to -0.5, and that therefore the gamma ray bursts are of galactic origin. It is claimed that the data are consistent with an upper limit over 100 times that proposed, and that therefore no conclusion can be drawn from the measurements regarding the nature or origin of gamma ray bursts. The resulting upper limit to the rate of occurrence of small bursts lies above the -1.5 index power law extrapolation of the size spectrum of known events, i.e., greater than the rate expected from an infinitely extended source region
A summary of recent NASA/Army contributions to rotorcraft vibrations and structural dynamics technology
The requirement for low vibrations has achieved the status of a critical design consideration in modern helicopters. There is now a recognized need to account for vibrations during both the analytical and experimental phases of design. Research activities in this area were both broad and varied and notable advances were made in recent years in the critical elements of the technology base needed to achieve the goal of a jet smooth ride. The purpose is to present an overview of accomplishments and current activities of govern and government-sponsored research in the area of rotorcraft vibrations and structural dynamics, focusing on NASA and Army contributions over the last decade or so. Specific topics addressed include: airframe finite-element modeling for static and dynamic analyses, analysis of coupled rotor-airframe vibrations, optimization of airframes subject to vibration constraints, active and passive control of vibrations in both the rotating and fixed systems, and integration of testing and analysis in such guises as modal analysis, system identification, structural modification, and vibratory loads measurement
One hundred angstrom niobium wire
Composite of fine niobium wires in copper is used to study the size and proximity effects of a superconductor in a normal matrix. The niobium rod was drawn to a 100 angstrom diameter wire on a copper tubing
Depolarizing GABAergic conductances regulate the balance of excitation to inhibition in the developing retinotectal circuit in vivo
Neurotransmission during development regulates synaptic maturation in neural circuits, but the contribution of different neurotransmitter systems is unclear. We investigated the role of GABAA receptor-mediated Cl- conductances in the development of synaptic responses in the Xenopus visual system. Intracellular Cl- concentration ([Cl-]i) was found to be high in immature tectal neurons and then falls over a period of several weeks. GABAergic synapses are present at early stages of tectal development and, when activated by optic nerve stimulation or visual stimuli, induce sustained depolarizing Cl- conductances that facilitate retinotectal transmission by NMDA receptors. To test whether depolarizing GABAergic inputs cooperate with NMDA receptors during activity-dependent maturation of glutamatergic synapses, we prematurely reduced [Cl-]i in tectal neurons in vivo by expressing the Cl- transporter KCC2. This blocked the normal developmental increase in AMPA receptor-mediated retinotectal transmission and increased GABAergic synaptic input to tectal neurons. Therefore, depolarizing GABAergic transmission plays a pivotal role in the maturation of excitatory transmission and controls the balance of excitation and inhibition in the developing retinotectal circuit
Helios-2 Vela-Ariel-5 gamma-ray burst source position
The gamma-ray burst of 28 January 1976, one of 18 events thus far detected in interplanetary space with Helios-2, was also observed with the Vela-5A, -6A and the Ariel-5 satellites. A small source field is obtained from the intersection of the region derived from the observed time delays between Helios-2 and Vela-5A and -6A with the source region independently found with the Ariel-5 X-ray detector. This area contains neither any steady X-ray source as scanned by HEAO-A nor any previously catalogued X-ray, radio or infrared sources, X-ray transients, quasars, seyferts, globular clusters, flare stars, pulsars, white dwarfs or high energy gamma-ray sources. The region is however, within the source field of a gamma-ray transient observed in 1974, which exhibited nuclear gamma-ray line structure
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