Joint attention and early social communication: implications for research on intervention with autism

Highly structured, intensive early intervention may lead to significant developmental gains for many children with autism. However, a clear understanding of early intervention effects may currently be hampered by a lack of precision in outcome measurement. To improve the precision and sensitivity of outcome assessment it may be useful to integrate research on the nature of the social disturbance of autism with research on early intervention. In this regard, it may be that measures of nonverbal social communication skills are especially important in the study of preschool intervention programs. This is because these measures appear to tap into a cardinal component of the early social disturbance of autism, and because these measures have been directly related to neurological, cognitive, and affective processes that may play a role in autism. The research and theory that support the potential utility of these types of measures for early intervention research are reviewed. Examples are provided to illustrate how these types of measures may assist in addressing current issues and hypotheses about early intervention with autism including the "recovery hypothesis," the "pivotal skill hypothesis," and the relative effectiveness of discrete trial versus incidental learning approaches to early intervention. A cybernetic model of autism is also briefly described in an effort to better understand one potential component of early psychoeducational treatment effects with children with autism.     

Improvement of Low‐Temperature zT in a Mg3Sb2–Mg3Bi2 Solid Solution via Mg‐Vapor Annealing

Materials with high zT over a wide temperature range are essential for thermoelectric applications. n‐Type Mg₃Sb₂‐based compounds have been shown to achieve high zT at 700 K, but their performance at low temperatures (<500 K) is compromised due to their highly resistive grain boundaries. Syntheses and optimization processes to mitigate this grain‐boundary effect has been limited due to loss of Mg, which hinders a sample's n‐type dopability. A Mg‐vapor anneal processing step that grows a sample's grain size and preserves its n‐type carrier concentration during annealing is demonstrated. The electrical conductivity and mobility of the samples with large grain size follows a phonon‐scattering‐dominated T^?3/2 trend over a large temperature range, further supporting the conclusion that the temperature‐activated mobility in Mg₃Sb₂‐based materials is caused by resistive grain boundaries. The measured Hall mobility of electrons reaches 170 cm² V^?1 s^?1 in annealed 800 °C sintered Mg_{3 + δ}Sb_1.49Bi_0.5Te_0.01, the highest ever reported for Mg₃Sb₂‐based thermoelectric materials. In particular, a sample with grain size >30 mm has a zT 0.8 at 300 K, which is comparable to commercial thermoelectric materials used at room temperature (n‐type Bi₂Te₃) while reaching zT 1.4 at 700 K, allowing applications over a wider temperature scale.     

Localization of the cellular expression of inhibin in trophoblastic tissue

We report four new cases of chordoma of "the mobile spine", all at the L2 level. Diagnosis was often delayed due to predominantly nonspecific low back symptoms; however, neurological involvement is more frequent than in chordoma with a sacrococcygeal localization. No pathognomonic images have been described for any imaging modality, and differential diagnosis should include metastases, chondrosarcoma, and giant-cell tumor. Histopathological analysis can be performed on CT-guided puncture biopsy samples, but a high level of suspicion must be present and, if there is any doubt, immunohistochemical studies should be carried out. Despite being the treatment of choice, complete tumor resection by a double-approach spondylectomy is barely feasible at the L2 level.     

Synthesis and characterization of cadmium telluride nanowire

CdTe nanowires with controlled composition were cathodically electrodeposited using track-etched polycarbonate membrane as scaffolds and their material and electrical properties were systematically investigated. As-deposited CdTe nanowires show nanocrystalline cubic phase structures with grain sizes of up to 60 nm. The dark-field images of nanowires reveal that the crystallinity of nanowires was greatly improved from nanocrystalline to a few single crystals within nanowires upon annealing at 200?°C for 6?h in a reducing environment (5%?H(2)+95%?N(2)). For electrical characterization, a single CdTe nanowire was assembled across microfabricated gold electrodes using the drop-casting method. In addition to an increase in grain size, the electrical resistivity of an annealed single nanowire (a few 10(5)?Ω?cm) was one order of magnitude greater than in an as-deposited nanowire, indicating that crystallinity of nanowires improved and defects within nanowires were reduced during annealing. By controlling the dopants levels (e.g.?Te content of nanowires), the resistivity of nanowires was varied from 10(4) to 10(0)?Ω?cm. Current-voltage (I-V) characteristics of nanowires indicated the presence of Schottky barriers at both ends of the Au/CdTe interface. Temperature-dependent I-V measurements show that the electron transport mode was determined by a thermally activated component at T>-50?°C and a temperature-independent component below -50?°C. Under optical illumination, the single CdTe nanowire exhibited enhanced conductance.     

Combinatorial chemistry, high‐speed screening and catalysis

Combinatorial and high‐speed screening techniques, which have revolutionized the search for new drug molecules, are now finding broader application in the chemical and materials development areas. The ability to generate large “libraries” of samples and to evaluate their performance simultaneously reduces the time and cost per sample and enables multicomponent parameter spaces to be explored. In the area of catalyst development, the impact of this technology promises to be substantial, not only in synthesis and performance evaluation, but also for the optimization of operating parameters. In this review, the major experimental approaches are described; for heterogeneous catalysts, especially, the parallel approach proves the most useful, rather than the “split‐and‐mix” methods of drug screening. Novel techniques for the high‐speed, parallel performance evaluation of catalyst arrays are reviewed with numerous recent examples. Indications are provided of expected future trends in this rapidly developing area. This revised version was published online in July 2006 with corrections to the Cover Date.     

Experimental and numerical investigation of turbulent jets issuing through a realistic pipeline geometry: Asymmetry effects for air,helium, and hydrogen

Experiments and numerical simulations were conducted to investigate the dispersion of turbulent jets issuing from realistic pipe geometries. The effect of jet densities and Reynolds numbers on vertical buoyant jets were investigated, as they emerged from the side wall of a circular pipe, through a round orifice. Particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) techniques were employed simultaneously to provide time-averaged flow velocity and concentrations fields. Large eddy simulation (LES) was applied to provide further detail with regards to the three-dimensionality of air, helium, and hydrogen jets. These jets were always asymmetric and found to deflect about the vertical axis. The deflection was influenced by buoyancy, where heavier gases deflected more than lighter gases. Significant turbulent mixing was also observed in the near field. The jets from realistic pipe geometries experienced faster velocity decay and asymmetric jet spreading compared to round jets. These findings indicate that conventional round jet assumptions are, to some extent, inadequate to predict gas concentration, entrainment rates and, consequently, the extent of the flammability envelope of realistic gas leaks.     

Laminar Forced-Convective Heat Transfer with Varying Properties in the Entrance Region of Flat Rectangular Ducts

Numerical results for air undergoing laminar forced-convective heat transfer in the entrance region of a flat rectangular duct with uniform wall temperature are obtained for Uniform inlet velocity and temperature profiles. The coupled governing partial differential equal ions are solved in discretized form with property variations being updated through physical property relations. This enables the physical property and thermofluid solutions to converge simultaneously, resulting in a realistic solution to the governing equations. Constant-property results are also obtained, and Nusselt numbers of both the constant-and variable-property models are compared with those of other numerical computations. The results of the variable-property model are also compared with available experimental data. The variable-property results exhibit excellent correlation with the available experimental data. A sensitivity analysis is performed to determine the effects of individual property variations on local Nusselt numbers.     

Tectonic and radioactivity impacts of 238U on groundwater-based drinking water at Gosa and Lugbe areas of Abuja,North Central Nigeria

Tectonic contribution of activity level of ²³⁸U in groundwater-based drinking water in Gosa and Lugbe areas of Abuja was measured using inductively coupled plasma mass spectrometry (ICP-MS). The highest activity level of 2736 µBq L^?1 reported in Lugbe borehole, whereas the lowest value of 443 µBq L^?1 reported at Gosa borehole. The inhabitants permanently used water from the boreholes for daily consumption. The group receives 5.55 × 10^?5 mSv of the annual collective effective dose due to ²³⁸U in drinking water. The radiological risks of ²³⁸U in the water samples were found to be low, typically in magnitude of 10^?7 with cancer mortality value of 1.03 × 10^?7 and morbidity value of 1.57 × 10^?7. The chemical toxicity risk of ²³⁸U in drinking water over a lifetime consumption has a mean value of 4.0 × 10^?3 μg kg^?1 day^?1. It could be that the human risk due to ²³⁸U content in groundwater supplies from ingestion may likely be the chemical toxicity of ²³⁸U as a heavy metal rather than radiological risk. Significantly, Lugbe subsurface may have developed some fractions of granitic strata that contributed to the distribution of radioactive of ²³⁸U in tectonically weak zones.     

The acylation and phosphorylation pattern of lipid A from Xanthomonas campestris strongly influence its ability to trigger the innate immune response in Arabidopsis

Lipopolysaccharides (LPSs) are major components of the cell surface of Gram-negative bacteria. LPSs comprise a hydrophilic heteropolysaccharide (formed by the core oligosaccharide and the O-specific polysaccharide) that is covalently linked to the glycolipid moiety lipid A, which anchors these macromolecules to the external membrane. LPSs are one of a group of molecules called pathogen-associated molecular patterns (PAMPs) that are indispensable for bacterial growth and viability, and act to trigger innate defense responses in eukaryotes. We have previously shown that LPS from the plant pathogen Xanthomonas campestris pv. campestris (Xcc) can elicit defense responses in the model plant Arabidopsis thaliana. Here we have extended these studies by analysis of the structure and biological activity of LPS from a nonpathogenic Xcc mutant, strain 8530. We show that this Xcc strain is defective in core completion and introduces significant modification in the lipid A region, which involves the degree of acylation and nonstoichiometric substitution of the phosphate groups with phosphoethanolamine. Lipid A that was isolated from Xcc strain 8530 did not have the ability to induce the defense-related gene PR1 in Arabidopsis, or to prevent the hypersensitive response (HR) that is caused by avirulent bacteria as the lipid A from the wild-type could. This suggests that Xcc has the capacity to modify the structure of the lipid A to reduce its activity as a PAMP. We speculate that such effects might occur in wild-type bacteria that are exposed to stresses such as those that might be encountered during plant colonization and disease.