Gamma ray spectrometry of LDEF samples at SRL

A total of 31 samples from the Long Duration Exposure Facility (LDEF), including materials of aluminum, vanadium, and steel trunnions were analyzed by ultra-low-level gamma spectrometry. The study quantified particle induced activations of Na-22, Sc-46, Cr-51, Mn-54, Co-56, Co-57, Co-58, and Co-60. The samples of trunnion sections exhibited increasing activity toward the outer end of the trunnion and decreasing activity toward its radial center. The trunnion sections did not include end pieces, which were reported to collect noticeable Be-7 on their leading surfaces. No significant Be-7 was detected in the samples analyzed

Intermediate wave-function statistics

We calculate statistical properties of the eigenfunctions of two quantum systems that exhibit intermediate spectral statistics: star graphs and Seba billiards. First, we show that these eigenfunctions are not quantum ergodic, and calculate the corresponding limit distribution. Second, we find that they can be strongly scarred by short periodic orbits, and construct sequences of states which have such a limit. Our results are illustrated by numerical computations.Comment: 4 pages, 3 figures. Final versio

No quantum ergodicity for star graphs

We investigate statistical properties of the eigenfunctions of the Schrodinger operator on families of star graphs with incommensurate bond lengths. We show that these eigenfunctions are not quantum ergodic in the limit as the number of bonds tends to infinity by finding an observable for which the quantum matrix elements do not converge to the classical average. We further show that for a given fixed graph there are subsequences of eigenfunctions which localise on pairs of bonds. We describe how to construct such subsequences explicitly. These constructions are analogous to scars on short unstable periodic orbits.Comment: 26 pages, 5 figure

Modern control concepts in hydrology

Two approaches to an identification problem in hydrology are presented based upon concepts from modern control and estimation theory. The first approach treats the identification of unknown parameters in a hydrologic system subject to noisy inputs as an adaptive linear stochastic control problem; the second approach alters the model equation to account for the random part in the inputs, and then uses a nonlinear estimation scheme to estimate the unknown parameters. Both approaches use state-space concepts. The identification schemes are sequential and adaptive and can handle either time invariant or time dependent parameters. They are used to identify parameters in the Prasad model of rainfall-runoff. The results obtained are encouraging and conform with results from two previous studies; the first using numerical integration of the model equation along with a trial-and-error procedure, and the second, by using a quasi-linearization technique. The proposed approaches offer a systematic way of analyzing the rainfall-runoff process when the input data are imbedded in noise

Line-profile tomography of exoplanet transits I: The Doppler shadow of HD 189733b

We present a direct method for isolating the component of the starlight blocked by a planet as it transits its host star, and apply it to spectra of the bright transiting planet HD 189733b. We model the global shape of the stellar cross-correlation function as the convolution of a limb-darkened rotation profile and a gaussian representing the Doppler core of the average photospheric line profile. The light blocked by the planet during the transit is a gaussian of the same intrinsic width, whose trajectory across the line profile yields a precise measure of the misalignment angle and an independent measure of v sin I. We show that even when v sin I is less than the width of the intrinsic line profile, the travelling Doppler "shadow" cast by the planet creates an identifiable distortion in the line profiles which is amenable to direct modelling. Direct measurement of the trajectory of the missing starlight yields self-consistent measures of the projected stellar rotation rate, the intrinsic width of the mean local photospheric line profile, the projected spin-orbit misalignment angle, and the system's centre-of-mass velocity. Combined with the photometric rotation period, the results give a geometrical measure of the stellar radius which agrees closely with values obtained from high-precision transit photometry if a small amount of differential rotation is present in the stellar photosphere.Comment: 8 pages, 5 figures, 2 tables; accepted by MNRA

Assessing conduct disturbance and fly ash exposure in children.

Minimal research has been conducted on fly ash (a byproduct of coal combustion) and health outcomes among exposed communities, and even less has looked at its effect on children’s behavior. This study specifically looks at fly ash exposure and conduct disturbance, using logistic regression to characterize their relationship. Conduct disturbance was gauged by t-scores of 55 or higher on the dimensions of aggression and delinquency of the Child Behavior Checklist. Fly ash exposure was determined by air and surface sampling of the children’s homes. While the odds ratios suggested fly ash exposure increases the likelihood of conduct disturbance, the results were not statistically significant. Future studies should have a larger sample size. If further research confirms a relationship between fly ash and conduct problems, this may lead to policy change and preventative measures. It is also important for community members to be informed of the potential hazards of fly ash, and for those exposed to know proper steps moving forward

HATS-1b: The First Transiting Planet Discovered by the HATSouth Survey

We report the discovery of HATS-1b, a transiting extrasolar planet orbiting the moderately bright V=12.05 G dwarf star GSC 6652-00186, and the first planet discovered by HATSouth, a global network of autonomous wide-field telescopes. HATS-1b has a period P~3.4465 d, mass Mp~1.86MJ, and radius Rp~1.30RJ. The host star has a mass of 0.99Msun, and radius of 1.04Rsun. The discovery light curve of HATS-1b has near continuous coverage over several multi-day periods, demonstrating the power of using a global network of telescopes to discover transiting planets.Comment: Submitted to AJ 10 pages, 5 figures, 6 table

Global Citizenship as a Function of Higher Education: The Demographic and Institutional Determinants in a Graduate Student Population

Over the last twenty years, the explosive growth in information technologies, combined with the globalization and easy access to other cultures, has allowed people to think of themselves more as citizens of the world than of a particular nation. Although the notion of “global citizenship” is often discussed in the popular press, little scholarly attention has been devoted to its measurement. Less attention has been paid to the role higher education plays in creating global citizens. To address these problems, a survey instrument was created to measure three facets of global citizenship: environmentalism, social justice, and civic responsibility, and was administered to 217 graduate students at two California universities. Two analytic techniques were applied to the data -- factor analysis to construct indices for each of the facets as well as for the overall construct, and regression analysis to decompose the variation in global citizenship scores into both demographic and institutional components. The results of the study suggest that significant variation exists regarding the level of global citizenship among the participants, with scores ranging from 32 to 59 on the (60 point) global citizenship scale. More importantly, this variation extended to file three facets of global citizenship, and when regression analysis was used to identify the determinants of each component, both demographic and institutional variables were found to be predictors of global citizenship. Specifically, higher levels of global citizenship were found to occur among older individuals, those fluent in more than one language, those with strong feelings regarding the sustainability of our planet\u27s resources, and those individuals that attended undergraduate institutions with large percentages of minority students. Taken together, the results of this study suggest that although both institutional and demographic variables were significant predictors of global citizenship, when broken down into the individual facets, institutionally manipulated variables explained more of the variation than did demographic variables. As such, institutions and researchers are encouraged to use this newly created measure of global citizenship to both measure the extent of global citizenship among students and to determine the extent to which the findings of this study are generalizable