Impairment in reciprocal social behavior (RSB), an essential component of early social competence, clinically defines autism spectrum disorder (ASD). However, the behavioral and genetic architecture of RSB in toddlerhood, when ASD first emerges, has not been fully characterized. We analyzed data from a quantitative video-referenced rating of RSB (vrRSB) in two toddler samples: a community-based volunteer research registry (n = 1,563) and an ethnically diverse, longitudinal twin sample ascertained from two state birth registries (n = 714). Variation in RSB was continuously distributed, temporally stable, significantly associated with ASD risk at age 18 months, and only modestly explained by sociodemographic and medical factors (r2 = 9.4%). Five latent RSB factors were identified and corresponded to aspects of social communication or restricted repetitive behaviors, the two core ASD symptom domains. Quantitative genetic analyses indicated substantial heritability for all factors at age 24 months (h2 ≥ .61). Genetic influences strongly overlapped across all factors, with a social motivation factor showing evidence of newly-emerging genetic influences between the ages of 18 and 24 months. RSB constitutes a heritable, trait-like competency whose factorial and genetic structure is generalized across diverse populations, demonstrating its role as an early, enduring dimension of inherited variation in human social behavior. Substantially overlapping RSB domains, measurable when core ASD features arise and consolidate, may serve as markers of specific pathways to autism and anchors to inform determinants of autism's heterogeneity.

In a recent Matters of the Record, Vermeij (1999) identifies what he regards as a fundamental problem with cladistic analysis. “The phylogenetic method,” he states (p. 431), “derives phylogeny in one part of the tree by relying on character-taxon relationships in another part of the tree, in direct violation of the principle that clades, once they have diverged from each other, are independent of one another.” Vermeij fails to appreciate the distinction between pattern-based cladograms, which are hierarchies founded on homology hypotheses, and logically contingent, process-based trees, which are depictions of temporal evolution. As a result, he treats cladograms as literal and direct estimates of evolution and thus confuses the treatment of characters and taxa in parsimony analyses with biological processes and interactions.

The effects of an embedded silver layer on the electrical properties of zinc oxide (ZnO) / silver (Ag)/ zinc oxide (ZnO) layered composite structures on polymer substrates have been investigated. We have engineered transparent conducting oxide structures with greatly improved conductivity. Electrical properties are correlated with Ag thickness. Film thicknesses were determined using Rutherford backscattering spectrometry. Hall effect, 4-point probe, and UV-Vis spectrophotometer analyses were used to characterize electrical and optical properties. The results show that carrier concentration, mobility, and conductivity increase with Ag thickness. Increasing Ag thickness from 8 to 14 nm enhances sheet resistance and resistivity by six orders of magnitude. We describe of the influence of Ag thickness on electrical properties of the ZnO/Ag/ZnO composite and propose a conduction mechanism for this system.

Extended abstract of a paper presented at Microscopy and Microanalysis 2007 in Ft. Lauderdale, Florida, USA, August 5 – August 9, 2007

The deposition and post-treatment processes involved in the production of porous organosilicate glasses (OSGs) by plasma-enhanced chemical vapor deposition (PECVD) with ultraviolet light (UV) treatment are investigated through the use of a deuterated organic porogen precursor using infrared spectroscopy and solid-state nuclear magnetic resonance spectroscopy. Infrared analysis provides evidence for hydrogen-deuterium scrambling between the chemical species during the deposition process, which is exacerbated by the UV treatment process. Analysis of 13C cross-polarized magic angle spinning (CP-MAS) NMR suggests that the porogen exists in domains relatively isolated from the network, in agreement with short UV treatment time morphological data that indicates the pore size is relatively constant from the early stages of UV treatment process. The chemical and morphological information provides further support for a deposition controlled morphology and has implications towards enhanced chemical processing of porous organosilicate glass (OSG) films for back-end-of-line integrated circuit manufacturing.

This work investigated the viability of tungsten-titanium barrier layers for silver metallization. Reactive sputtered W-Ti was deposited on a Si wafer followed by an Ag thin film over layer. These samples were then annealed in vacuum at temperatures up to 700 °C. Characterization of these samples included using x-ray diffractometry, Rutherford backscattering spectrometry, scanning transmission microscopy, secondary ion mass spectroscopy, transmission electron microscopy, and four point probe analysis. The results indicated that the metal/diffusion barrier stack was stable up to 600 °C. Silicon started moving into the tungsten-titanium film at temperatures above 600 °C. Movement of Si resulted in local Si voiding. These results showed the promise of W-Ti as an effective barrier layer for silver metallization for process temperatures below 600 °C.

Intrinsic biaxial strain values of strained Si on insulator (SSOI) layers were measured using symmetric Bragg-Brentano configuration (i.e., {004} θ-2θ scans) and asymmetric {224} rocking curves. We confirmed that the twist angle between the layer and substrate can be incorporated into the biaxial strain equations for epitaxial layers. Moreover, as the samples were annealed up to 1200°C, the tensile parallel strains increased from 0.56% to 0.7%. Since both the overlying strained Si and underlying substrate maintained a stressed state in the buried SiO2, the compressively strained oxide retained the lattice expansion of the overlying strained Si and resulted in the increasing parallel strains after annealing.

Grazing experiments have shown that using a ryegrass (Lolium perenne L.) variety bred by conventional techniques for high water-soluble carbohydrate (WSC) concentrations can improve liveweight gain in pre-weaned lambs (Lee et al., 2001) and increase milk yields and reduce N excretion in dairy cows (Miller et al., 2001) compared to conventional ryegrass. The aim of this study was to determine the effects of using reseeded upland pastures, sown with either a ryegrass variety bred for elevated levels of WSC or a control ryegrass on the production performance of grazing steers when compared to steers grazing permanent ryegrass/white clover pastures.