Shape-dependent oriented trapping and scaffolding of plasmonic nanoparticles by topological defects for self-assembly of colloidal dimers in liquid crystals

We demonstrate scaffolding of plasmonic nanoparticles by topological defects induced by colloidal microspheres to match their surface boundary conditions with a uniform far-field alignment in a liquid crystal host. Displacing energetically costly liquid crystal regions of reduced order, anisotropic nanoparticles with concave or convex shapes not only stably localize in defects but also self-orient with respect to the microsphere surface. Using laser tweezers, we manipulate the ensuing nanoparticle-microsphere colloidal dimers, probing the strength of elastic binding and demonstrating self-assembly of hierarchical colloidal superstructures such as chains and arrays.     

Thermal properties and performance of carbon fiber-based ultra-high temperature ceramic matrix composites (Cf-UHTCMCs)

The thermophysical properties of carbon fiber-based ultra-high temperature ceramic matrix composites have been determined to aid designers who need these properties when considering using the composites in ultra-high temperature aerospace applications. The coefficient of thermal expansion (CTE) and thermal diffusivity of the composites were measured parallel and perpendicular to the ply direction; the thermal conductivity was measured using the laser-flash method and the heat capacity calculated from the relationship between the thermal diffusivity, density, and thermal conductivity. Both the CTE and thermal conductivity showed higher values across the ply and increased with increasing temperature as expected, whilst the thermal diffusivity showed higher values parallel to the ply and increased smoothly with temperature. In addition, two different but related oxyfuel torch tests, based on oxyacetylene and oxypropane, were used to evaluate the thermo-ablation behavior of the composites. The tests showed how good the composites were at withstanding the ultra-high temperatures, high heat fluxes, and gas velocities involved.     

Current-events knowledge in adults: An investigation of age, intelligence, and nonability determinants.

This study expanded the scope of knowledge typically included in intellectual assessment to incorporate domains of current-event knowledge from the 1930s to the 1990s across the areas of art/humanitites, politics/economics, popular culture, and nature/science/technology. Results indicated that age of participants was significantly and positively related to knowledge about current events. Moreover, fluid intelligence was a less effective predictor of knowledge levels than was crystallized intelligence. Personality (i.e., Openness to Experience) and self-concept were also positively related to current-events knowledge. The results are consistent with an investment theory of adult intellect, which views development as an ongoing outcome of the combined influences of intelligence-as-process, personality, and interests, leading to intelligence-as-knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Computing, Social Activity, and Entertainment: A Field Study of a Game MUD

Are game and entertainment systems different than work-oriented systems? What drives the user's experience in a collaborative game? To answer these questions, we performed a participant-observation study of a combat MUD, a game similar to Dungeons and Dragons. Our interest is in how this social world is arranged and managed (rather than, for example, in how participants form or display individual identities). The study explores the social arrangements and activities that give meaning and structure to the participants. We found that conflict and cooperation were the dominant social activities on this MUD, much more so than sociability. The game's management played a critical function in maintaining and promoting these activities. Moreover, novelty and entertainment were important for the design of both the system features and the sociality itself.     

Role of small bowel biopsy in the endoscopic evaluation of adults with iron deficiency anemia

OBJECTIVES: The recommended evaluation of adult patients presenting with iron deficiency anemia (IDA) includes the performance of colonoscopy and esophagogastroduodenoscopy. IDA is a common feature in patients with celiac disease and, in several, may be the only presenting sign. The performance of small bowel biopsy (SBB) for the evaluation of celiac disease as the cause of IDA is not routinely recommended. The aim of the present study was to determine the yield of SBB performed during routine endoscopy of adults with IDA. METHODS: We prospectively studied 93 patients with IDA. Three control groups were included: 23 patients with steatorrhea, 37 patients with idiopathic diarrhea, and 9 patients in whom SBB was performed for miscellaneous indications. RESULTS: Eleven patients with IDA and two patients with steatorrhea had SBB findings compatible with celiac disease. None of the patients from the other two groups had similar findings. Two patients with IDA, who were later diagnosed to suffer from celiac disease, presented: one with occult blood in the stool and the other with rectal bleeding. Subgroup analysis of patients with IDA revealed that patients with celiac disease were younger, had significantly more episodes of diarrhea, lower mean hemoglobin level, and longer duration of anemia than those without celiac disease. Other mucosal abnormalities were found in a substantial number of patients with celiac disease: esophagitis, gastritis, duodenitis, hemorrhoids, and colitis. CONCLUSIONS: A substantial number of adult Israeli patients who present with IDA are found, on SBB, to have mucosal abnormalities compatible with the diagnosis of celiac disease. The presence of esophagitis, gastritis, or duodenitis on esophagogastroduodenoscopy, or other abnormalities on colonoscopy, do not exclude the coexistence of celiac disease. Celiac disease should be included and routinely looked for in the differential diagnosis of adult patients with IDA.     

Differential effects of the Rac GTPase on Purkinje cell axons and dendritic trunks and spines

Neurons contain distinct compartments including dendrites, dendritic spines, axons and synaptic terminals. The molecular mechanisms that generate and distinguish these compartments, although largely unknown, may involve the small GTPases Rac and Cdc42, which appear to regulate actin polymerization. Having shown that perturbations of Rac1 activity block the growth of axons but not dendrites of Drosophila neurons, we investigated whether this also applies to mammals by examining transgenic mice expressing constitutively active human Rac1 in Purkinje cells. We found that these mice were ataxic and had a reduction of Purkinje-cell axon terminals in the deep cerebellar nuclei, whereas the dendritic trees grew to normal height and branched extensively. Unexpectedly, the dendritic spines of Purkinje cells in developing and mature cerebella were much reduced in size but increased in number. These 'mini' spines often form supernumerary synapses. These differential effects of perturbing Rac1 activity indicate that there may be distinct mechanisms for the elaboration of axons, dendrites and dendritic spines.     

On the design parameters of flip-chip PBGA package assembly foroptimum solder ball reliability

An experimental investigation of the warpage of a flip-chip plastic ball grid array package assembly is presented and a critical deformation mode is identified. The experimental data, documented while cooling the assembly from the underfill curing temperature to -40°C, clearly reveal the effect of the constraints from the chip and the PCB on the global behavior of the substrate. The constraints produce an inflection point of the substrate at the edge of the chip. An experimentally verified three-dimensional (3-D) nonlinear finite element analysis proceeds to quantify the effect of the substrate behavior on the second-level solder ball strains. An extensive parametric study is conducted to identify the most critical design parameter for optimum solder ball reliability