Magnetic Gaps related to Spin Glass Order in Fermionic Systems

We provide evidence for spin glass related magnetic gaps in the fermionic density of states below the freezing temperature. Model calculations are presented and proposed to be relevant for explaining resistivity measurements which observe a crossover from variable-range- to activated behavior. The magnetic field dependence of a hardgap and the low temperature decay of the density of states are given. In models with fermion transport a new metal-insulator transition is predicted to occur due to the spin-glass gap, anteceding the spin glass to quantum paramagnet transition at smaller spin density. Important fluctuation effects due to finite range frustrated interactions are estimated and discussed.Comment: 4 pages, 1 Postscript figure, revised version accepted for publication in Physical Review Letter

The mechanical stability of polyimide films at high pH

Polyimide insulated electrical wire has been widely used in the aerospace industry in commercial, military, and to a lesser degree, general aviation aircraft since the early 1970s. Wiring failures linked to insulation damage have drawn much attention in the media and concerns have developed regarding the long term stability and safety of polyimide insulated electrical wire. The mechanical durability and chemical stability of polyimide insulated wire are affected by hydrolysis, notch propagation, wet and dry arc tracking, topcoat flaking, and degradation due to high pH fluids. Several polyimides were selected for evaluation for resistance to degradation by various aqueous alkaline solutions. The polyimides under evaluation include commercially available films such as KAPTON (tradename), APICAL (tradename), LARC-TPI, and UPILEX (tradename) R and S, as well as a number of experimental films prepared at NASA-Langley. Material properties investigated include viscosity, solubility, moisture absorption, glass transition temperature, dielectric constant, and mechanical properties before and after exposure to various conditions

Effects of dry-extruded whole soybeans on growth performance of nursery pigs and growth performance, carcass characteristics, and stomach morphology of finishing pigs

In a 3 I-d nursery experiment, replacing soybean meal (SBM) with dry-extruded whole soybeans (DEWS) tended to improve F/G (6% overall difference), but ADG was not affected. Adjusting the diet with DEWS to the nutrient:calorie ratio of the diet with SBM did not greatly improve growth performance compared to the diet that was simply formulated to the same concentration of lysine as the diet with SBM. In a second experiment (with finishing pigs), 50 and 100% of the SBM in a corn-based diet was replaced with DEWS. Replacement resulted in 2% greater ADG and 8% better F/G, without significantly increasing carcass fatness or the incidence of stomach ulcers. Our data suggest that DEWS are an acceptable (if not superior) alternative to SBM in diets for nursery and finishing pigs.; Swine Day, Manhattan, KS, November 16, 199

Turbulence Nonlinearities Shed Light on Geometric Asymmetry in Tokamak Confinement Transitions

A comprehensive study of fully frequency-resolved nonlinear kinetic energy transfer has been performed for the first time in a diverted tokamak, providing new insight into the parametric dependences of edge turbulence transitions. Measurements using gas puff imaging in the turbulent L-mode state illuminate the source of the long known but as yet unexplained "favorable-unfavorable" geometric asymmetry of the power threshold for transition to the turbulence-suppressed H mode. Results from the recently discovered I mode point to a competition between zonal flow (ZF) and geodesic-acoustic modes (GAM) for turbulent energy, while showing new evidence that the I-to-H transition is still dominated by ZFs. The availability of nonlinear drive for the GAM against net heat flux through the edge corresponds very well to empirical scalings found experimentally for accessing the I mode

The Chromospheric Activity and Ages of M Dwarf Stars in Wide Binary Systems

We investigate the relationship between age and chromospheric activity for 139 M dwarf stars in wide binary systems with white dwarf companions. The age of each system is determined from the cooling age of its white dwarf component. The current limit for activity-age relations found for M dwarfs in open clusters is 4 Gyr. Our unique approach to finding ages for M stars allows for the exploration of this relationship at ages older than 4 Gyr. The general trend of stars remaining active for a longer time at later spectral type is confirmed. However, our larger sample and greater age range reveals additional complexity in assigning age based on activity alone. We find that M dwarfs in wide binaries older than 4 Gyr depart from the log-linear relation for clusters and are found to have activity at magnitudes, colors and masses which are brighter, bluer and more massive than predicted by the cluster relation. In addition to our activity-age results, we present the measured radial velocities and complete space motions for 161 white dwarf stars in wide binaries.Comment: 22 pages including 9 figures and 5 tables. Accepted for publication in The Astronomical Journa