Evolution of the bilayer nu = 1 quantum Hall state under charge imbalance

We use high-mobility bilayer hole systems with negligible tunneling to examine how the bilayer nu = 1 quantum Hall state evolves as charge is transferred from one layer to the other at constant total density. We map bilayer nu = 1 state stability versus imbalance for five total densities spanning the range from strongly interlayer coherent to incoherent. We observe competition between single-layer correlations and interlayer coherence. Most significantly, we find that bilayer systems that are incoherent at balance can develop spontaneous interlayer coherence with imbalance, in agreement with recent theoretical predictions.Comment: 4 pages, 4 figure

Towards Rapid Parameter Estimation on Gravitational Waves from Compact Binaries using Interpolated Waveforms

Accurate parameter estimation of gravitational waves from coalescing compact binary sources is a key requirement for gravitational-wave astronomy. Evaluating the posterior probability density function of the binary's parameters (component masses, sky location, distance, etc.) requires computing millions of waveforms. The computational expense of parameter estimation is dominated by waveform generation and scales linearly with the waveform computational cost. Previous work showed that gravitational waveforms from non-spinning compact binary sources are amenable to a truncated singular value decomposition, which allows them to be reconstructed via interpolation at fixed computational cost. However, the accuracy requirement for parameter estimation is typically higher than for searches, so it is crucial to ascertain that interpolation does not lead to significant errors. Here we provide a proof of principle to show that interpolated waveforms can be used to recover posterior probability density functions with negligible loss in accuracy with respect to non-interpolated waveforms. This technique has the potential to significantly increase the efficiency of parameter estimation.Comment: 7 pages, 2 figure

Investigation to relate the chlorophyll and suspended sediment content in the waters of the lower Chesapeake Bay to ERTS-1 imagery

There are no author-identified significant results in this report

Correlation of ERTS multispectral imagery with suspended matter and chlorophyll in lower Chesapeake Bay

The feasibility of using multispectral satellite imagery to monitor the characteristics of estuarine waters is being investigated. Preliminary comparisons of MSS imagery with suspended matter concentrations, particle counts, chlorophyll, transmittance and bathymetry have been made. Some visual correlation of radiance with particulates and chlorophyll has been established. Effects of bathymetry are present, and their relation to transmittance and radiance is being investigated. Greatest detail in suspended matter is revealed by MSS band 5. Near-surface suspended sediment load and chlorophyll can be observed in bands 6 and 7. Images received to date have partially defined extent and location of high suspensate concentrations. Net quantity of suspended matter in the lower Bay has been decreasing since the inception of the study, and represents the diminution of turbid flood waters carried into the Bay in late September, 1972. The results so far point to the utility of MSS imagery in monitoring estuarine water character for the assessment of siltation, productivity, and water types

Intimate Partner Violence in Rural Low-Income Families: Correlates and Change in Prevalence Over the First 5 Years of a Child’s Life

Despite evidence that individuals living in low-income and rural communities may be at heightened risk for intimate partner violence (IPV), little is known about the prevalence and nature of IPV occurring in these communities. The goal of the current study, therefore, was to characterize IPV occurring in a population-based sample of families living in communities characterized by rural poverty. Specifically, we examined the prevalence, severity, and chronicity of IPV occurring in this high-risk sample, as well as the demographic correlates thereof. Using data from multiple assessments across the first five years of their child’s life, we also examined changes in the prevalence of IPV across this time. Results indicate that IPV was most prevalent around the birth of the target child and that the population-level prevalence of IPV decreased significantly over the subsequent five years. Although previous research suggests that children under the age of five are at heightened risk for IPV relative to older children, this is the first study to our knowledge to demonstrate that there are changes in the prevalence of IPV within this high-risk age period

Electrolytes Based on Primary Ammonium Salts as Ionic Liquids for PEMFC-membranes

Physico-chemical characterization of a series of salts prepared from primary amines was performed in order to obtain the salts as protonic ionic liquids (PILs). It was shown that the majority of these salts are thermally stable up to 400 °C, while the melting point of each salt depends on the nature of the anion and amine substitutions. The results of cyclic voltammetry experiments showed that the amines and the salts (HNR3+, A–) could be oxidized only at very high potentials (> 1.9 V/SHE) which is compatible with their use in PEM fuel cells. Conductivities of salts at 130 °C are between 0.01 and 13 mS cm–1. The best conductivity was observed for the salt resulting from asymmetric amines/trifluoromethanesulfonic acid association. Incorporation of these compounds within Nafion® has also been studied, particularly with respect to the compatibility of PIL/Nafion® and conductivity of these newly formed membranes

Correlation of chlorophyll, suspended matter, and related parameters of waters in the lower Chesapeake Bay area to LANDSAT-1 imagery

The author has identified the following significant results. An effort to relate water parameters of the lower Chesapeake Bay area to multispectral scanner images of LANDSAT 1 has shown that some spectral bands can be correlated to water parameters, and has demonstrated the feasibility of synoptic mapping of estuaries by satellite. Bands 5 and 6 were shown to be useful for monitoring total particles. Band 5 showed high correlation with suspended sediment concentration. Attenuation coefficients monitored continuously by ship along three baselines were cross correlated with radiance values on three days. Improved correlations resulted when tidal conditions were taken into consideration. A contouring program was developed to display sediment variation in the lower Chesapeake Bay from the MSS bands

Spin Susceptibility and Gap Structure of the Fractional-Statistics Gas

This paper establishes and tests procedures which can determine the electron energy gap of the high-temperature superconductors using the $t\!-\!J$ model with spinon and holon quasiparticles obeying fractional statistics. A simpler problem with similar physics, the spin susceptibility spectrum of the spin 1/2 fractional-statistics gas, is studied. Interactions with the density oscillations of the system substantially decrease the spin gap to a value of $(0.2 \pm 0.2)$ $\hbar \omega_c$, much less than the mean-field value of $\hbar\omega_c$. The lower few Landau levels remain visible, though broadened and shifted, in the spin susceptibility. As a check of the methods, the single-particle Green's function of the non-interacting Bose gas viewed in the fermionic representation, as computed by the same approximation scheme, agrees well with the exact results. The same mechanism would reduce the gap of the $t\!-\!J$ model without eliminating it.Comment: 35 pages, written in REVTeX, 16 figures available upon request from [email protected]