Light quark masses from Domain Wall Fermions

We present results for the renormalised light and strange quark masses calculated using Domain Wall Fermions in quenched QCD. New results using the DBW2 gauge action at inverse lattice spacings of approximately 2 GeV and 1.3 GeV will be presented and compared against existing results at 2 GeV using the Wilson gauge action. This comparison allows a study of the uncertainties due to both finite lattice spacing and residual chiral symmetry breaking effects.Comment: Lattice2002(spectrum), 3 pages, 4 figures. Added referenc

ALCOA #1 (41AN87): A Frankston Phase Settlement along Mound Prairie Creek, Anderson County, Texas

The ALCOA #1 (41AN87) site is a Frankston Phase (ca. A.D. 1400-1650) site located on a high alluvial terrace of Mound Prairie Creek, about seven kilometers northeast of Palestine, Texas. Mound Prairie Creek, a perennial stream, flows southeast to east across the county and drains into the Neches River. The site is approximately 10 meters above the Mound Prairie Creek floodplain, and the creek channel is 300 meters to the south. Although the investigations at the site have been rather limited to date, it appears that the ALCOA #1 site is a single component Frankston Phase homestead, or possibly a small hamlet. Other Frankston phase sites are known on Mound Prairie Creek, Hurricane Creek, Walnut Creek, and Brushy Creek, all Neches River tributaries, and the possibility exists that these may be part of a larger related Caddo community and settlement system

Primary neuronal degeneration in the guinea pig effects on spontaneous rate-type

Thesis (Ph. D.)--Harvard-MIT Program in Health Sciences and Technology.Cataloged from PDF version of thesis.Includes bibliographical references (p. 63-66).Acoustic overexposure can cause death of cochlear nerve fibers, even if elevations in cochlear sensitivity are reversible and even if there is no hair cell loss. We hypothesized that this primary neural degeneration does not raise cochlear thresholds because it is selective for cochlear neurons with high thresholds and low spontaneous rates (SRs). We tested this hypothesis by recording from single cochlear neurons in guinea pigs and evaluating neuronal degeneration via confocal microscopy 14 days after exposure to noise (4-8kHz, 106dB SPL, 2 hrs). Suprathreshold amplitudes of otoacoustic emissions recovered post-exposure, suggesting complete hair cell recovery; suprathreshold amplitudes of the auditory brainstem response remained attenuated for high-frequency stimuli, consistent with primary neural degeneration in the basal half of the cochlea. Single-fiber recordings from exposed animals showed that all sound-evoked response properties, including threshold, sharpness of tuning, maximum discharge rate, dynamic range, response adaptation, and recovery from forward masking, were indistinguishable from responses recorded from unexposed controls. The only physiological abnormalities were revealed in the population statistics: in high-frequency regions where low- SR (<20sp/sec) fibers are 47% of the control ear, that number was reduced to 29% in the exposed ear. Cochlear afferent synapses were counted after immunostaining for juxtaposed pre-synaptic ribbons and post-synaptic glutamate receptor patches in the inner hair cell area. The observed 20% synapse loss throughout the basal half of the cochlea was consistent with the physiological data. Analysis of synaptic morphology suggested remaining pre-synaptic ribbons were hypertrophied and membrane localization of post-synaptic glutamate receptors was reduced. The significance of the ribbon hypertrophy is unclear, but reduced receptor expression may represent receptor internalization, suggested as a mechanism to minimize the glutamate excitotoxicity that underlies this noise-induced degeneration. In the normal ear, fibers with high thresholds and low SRs are relatively insensitive to masking, thus are important for hearing in a noisy environment. We speculate that over a lifetime of repeated moderate noise exposure, the typical human ear may selectively lose these low-SR fibers and that this selective neuropathy may be an important contributor to the well-known problems with hearing-in-noise in the aging ear.by Adam C. Furman.Ph.D

Formation of plasma around a small meteoroid: 1. Kinetic theory

This article is a companion to Dimant and Oppenheim [2017] https://doi.org/10.1002/2017JA023963.This paper calculates the spatial distribution of the plasma responsible for radar head echoes by applying the kinetic theory developed in the companion paper. This results in a set of analytic expressions for the plasma density as a function of distance from the meteoroid. It shows that at distances less than a collisional mean free path from the meteoroid surface, the plasma density drops in proportion to 1/R where R is the distance from the meteoroid center; and, at distances much longer than the mean‐free‐path behind the meteoroid, the density diminishes at a rate proportional to 1/R2. The results of this paper should be used for modeling and analysis of radar head echoes.This work was supported by NSF grant AGS-1244842. (AGS-1244842 - NSF

Master Equation for Hydrogen Recombination on Grain Surfaces

Recent experimental results on the formation of molecular hydrogen on astrophysically relevant surfaces under conditions similar to those encountered in the interstellar medium provided useful quantitative information about these processes. Rate equation analysis of experiments on olivine and amorphous carbon surfaces provided the activation energy barriers for the diffusion and desorption processes relevant to hydrogen recombination on these surfaces. However, the suitability of rate equations for the simulation of hydrogen recombination on interstellar grains, where there might be very few atoms on a grain at any given time, has been questioned. To resolve this problem, we introduce a master equation that takes into account both the discrete nature of the H atoms and the fluctuations in the number of atoms on a grain. The hydrogen recombination rate on microscopic grains, as a function of grain size and temperature, is then calculated using the master equation. The results are compared to those obtained from the rate equations and the conditions under which the master equation is required are identified.Comment: Latex document. 14 pages of text. Four associated figs in in PS format on separate files that are "called-in" the LaTeX documen

Overview of MSFC Additive Electronics Capabilities

Focus: Marshall seeks to support the Agency in the development of next generation printed electronics technologies for living and working in space, with emphasis on enhanced electronics manufacturing processes and capabilities development on the ground and in-space. Near-Term: Human Habitation Elements and Life Support Systems - pursuing integrated flexible wearable air, water, vital monitoring solutions for next generation printed technologies; Complete startup printing technology demonstrations which prove basic processes and establish ISM (In-Space Manufacturing) infrastructure needed for future applications including metals based manufacturing. Medium Term: Target low-cost research and demonstration activities that support multi-material additive manufacturing, more sophisticated parts production, printed electronics and ISM; Maturation and flight demonstration of printed propulsion system components, with emphasis on infusion into small-spacecraft-based missions. Long-Term: Evolve systems capabilities to be supportive of destination (lunar or Mars) resources and requirements, increase autonomy in systems and utilize in-situ resources towards manufacturing; Support development of self-replicable systems and their infusion into future spacecraft and missions

Considerations on Neuberger's operator

We discuss new approaches to the numerical implementation of Neuberger's operator for lattice fermions and the possible use of block spin transformations.Comment: LATTICE 99 (Improvement and Renormalization

Studies of the beam-beam interaction for the LHC

We have used the beam-beam simulation code CBI to study the beam-beam interaction for the LHC. We find that for nominal LHC parameters, and assuming only one bunch per beam, there are no collective (coherent) beam-beam instabilities. We have investigated the effect of sweeping one of the beams around the other (a procedure that could be used as a diagnostic for head-on beam-beam collisions), We find that this does not cause any problems at the nominal current, though at higher currents there can be beam blow-up and collective beam motion. (4 refs)