A study of charge storage in silicon oxide resulting from non-penetrating electron irradiation

Charge storage in silicon dioxide resulting from electron irradiatio

Tertiary Climate Change and the Diversification of the Amazonian Gecko Genus Gonatodes (Sphaerodactylidae, Squamata)

The genus Gonatodes is a monophyletic group of small-bodied, diurnal geckos distributed across northern South America, Central America, and the Caribbean. We used fragments of three nuclear genes (RAG2, ACM4, and c-mos) and one mitochondrial gene (16S) to estimate phylogenetic relationships among Amazonian species of Gonatodes. We used Penalized Likelihood to estimate timing of diversification in the genus. Most cladogenesis occurred in the Oligocene and early Miocene and coincided with a burst of diversification in other South American animal groups including mollusks, birds, and mammals. The Oligocene and early Miocene were periods dominated by dramatic climate change and Andean orogeny and we suggest that these factors drove the burst of cladogenesis in Gonatodes geckos as well as other taxa. A common pattern in Amazonian taxa is a biogeographic split between the eastern and western Amazon basin. We observed two clades with this spatial distribution, although large differences in timing of divergence between the east–west taxon pairs indicate that these divergences were not the result of a common vicariant event

The Stellar Content Near the Galactic Center

High angular resolution J, H, K, and L' images are used to investigate the stellar content within 6 arcsec of SgrA*. The data, which are complete to K ~ 16, are the deepest multicolor observations of the region published to date.Comment: 34 pages, including 12 figure

On the ground electronic states of copper silicide and its ions

The low-lying electronic states of SiCu, SiCu^+, and SiCu^− have been studied using a variety of high-level ab initio techniques. As expected on the basis of simple orbital occupancy and bond forming for Si(s^2p^2)+Cu(s^1) species, ^2Π_r, ^1Σ^+, and ^3Σ^− states were found to be the ground electronic states for SiCu, SiCu^+, and SiCu^−, respectively; the ^2Π_r state is not that suggested in most recent experimental studies. All of these molecules were found to be quite strongly bound although the bond lengths, bond energies, and harmonic frequencies vary slightly among them, as a result of the nonbonding character of the 2π-MO (molecular orbital) [composed almost entirely of the Si 3p-AO (atomic orbital)], the occupation of which varies from 0 to 2 within the ^1Σ^+, ^2Π_r, and ^3Σ^− series. The neutral SiCu is found to have bound excited electronic states of ^4Σ^−, ^2Δ, ^2Σ^+, and ^2Π_i symmetry lying 0.5, 1.2, 1.8, and 3.2 eV above the ^2Π_r ground state. It is possible but not yet certain that the ^2Π_i state is, in fact, the “B state” observed in the recent experimental studies by Scherer, Paul, Collier, and Saykally

Itinerant ferromagnetism in an atomic Fermi gas: Influence of population imbalance

We investigate ferromagnetic ordering in an itinerant ultracold atomic Fermi gas with repulsive interactions and population imbalance. In a spatially uniform system, we show that at zero temperature the transition to the itinerant magnetic phase transforms from first to second order with increasing population imbalance. Drawing on these results, we elucidate the phases present in a trapped geometry, finding three characteristic types of behavior with changing population imbalance. Finally, we outline the potential experimental implications of the findings.Comment: 10 pages, 4 figures, typos added, references adde

Experimental study of turbulent coherent structures using particle image velocimetry and hydrogen bubble visualisation techniques

The characteristics of coherent structures in turbulent boundary layers were investigated experimentally using PIV and hydrogen bubble visualisation techniques. Turbulent boundary layers were generated and tested in two flumes with different scale, for two Reynolds numbers: Re=32,000 Re=32,000 and 71,200, both over a smooth bed. Measurements from the PIV technique and hydrogen bubble visualisation lead to the same research findings, suggesting a linear relationship between the instantaneous integral spatial scale and the instantaneous spacing between turbulent streaks. This new approach to determining the streak spacing provides some guidance for experimentalists in terms of experimental methodology. Results of hydrogen bubble visualisations provide additional evidence that streamwise vortices reside near low-speed streaks. Detailed statistical analysis further demonstrates the better performance of Burr distribution for the probability density function of streak spacing. Combining the measurements of flow field in the horizontal and vertical plane, streamwise vortices are observed to be tilted ± 8∘±8∘ in the (x, z) plane and shear layers are inclined to the wall at 30∘30∘ in the (x, y) plane

Concordance among physical educators’, teachers’, and parents’ perceptions of attention problems in children

Objective: The study examined the concordance among rating sources on attention problems of elementary school–aged children. Method: A randomly selected sample (N = 841) of children was rated by the physical educators, the teachers,and the parents, using the Attention Scales of the Motor Behavior Checklist (MBC), the Teacher Report Form, the Child Behavior Checklist, and the ADHD–Rating Scale–IV (ADHD-RS-IV ). Results: Convergent validity of the Lack of Attention Scale of the MBC with the corresponding subscales was supported. Correlations were higher between teachers’ ratings and between physical educators’ and teachers’ ratings than between physical educators’ and parents’ ratings or between teachers’ and parents’ ratings. Conclusion: Findings underscore the importance of taking the child’s settings and observer influences into account and suggest that MBC is a new promising instrument for screening attention problems in school settings

Agreement among physical educators, teachers and parents on children’s behaviors: A multitrait–multimethod design approach

The study examines the agreement among raters on children’s problematic behaviors. A multitrait–multimethod (MTMM) matrix was applied to a normative sample of elementary school-aged children (N = 841). The participants were rated by their physical educators, using the Motor Behavior Checklist for children (MBC; Efstratopoulou, Janssen,& Simons, 2012). Teachers and parents rated the same students using the Teacher Report Form (TRF; Achenbach, 1991b), the Child Behavior Checklist (CBCL; Achenbach, 1991a)and the ADHD Rating Scale-IV (DuPaul, Power, Anastopoulos, & Reid, 1998). The resulting matrix revealed significant correlations for the Rules Breaking, Lack of Attention, Hyperactivity/Impulsivity, Lack of Social interaction problem scale and for the Internalizing, Externalizing and Total scores. Convergent validity of the specific MBC subscales was supported by significant correlations with the corresponding subscales of TRF, CBCL and ADHD Rating Scale-IV. Findings underscore the importance of taking child’s settings and observer influences into account and suggest that MBC is a new promising instrument that can provide valid ratings on externalizing behavior and social problems in children when used by physical educators in school settings

RESCUE Testing of Full-Scale In-Situ Structures

At SRI International a state-of-the-art technique for testing large-scale structures to dynamic motion resembling that from a large magnitude earthquake has been developed. The technique, referred to as repeatable earth shaking by controlled underground expansion (RESCUE), may allow actual full-scale structures to be tested in-situ. In this paper we present the results of a finite element simulation of a full-scale highway overpass loaded from ground motion produced by the RESCUE technique. Results indicated that the RESCUE technique could generate significantly enough ground motion to excite failure damage modes