Lateralized human cortical activity for shifting visuospatial attention and initiating saccades

Lateralized human cortical activity for shifting visuospatial attention and initiating saccades. J. Neurophysiol. 80: 2900-2910, 1998. The relation between shifts of visual attention and saccade preparation was investigated by studying their electrophysiological correlates in human scalp-recorded electroencephalogram (EEG). Participants had to make saccades either to a saliently colored or to a gray circle, simultaneously presented in opposite visual hemifields, under different task instructions. EEG was measured within the short interval between stimulus onset and saccade, focusing on lateralized activity, contralateral either to the side of the relevant stimulus or to the direction of the saccade. Three components of lateralization were found: 1) activity contralateral to the relevant stimulus irrespective of saccade direction, peaking 250 ms after stimulus onset, largest above lateral parietal sites, 2) activity contralateral to the relevant stimulus if the stimulus was also the target of the saccade, largest 330-480 ms after stimulus onset, widespread over the scalp but with a focus again above lateral parietal sites, and 3) activity contralateral to saccade direction, beginning about 100 ms before the saccade, largest above mesial parietal sites, with some task-dependent fronto-central contribution. Because of their sensitivity to task variables, component 1 is interpreted as the shifting of attention to the relevant stimulus, component 2 is interpreted as reflecting the enhancement of the attentional shift if the relevant stimulus is also the saccade target, and component 3 is interpreted as the triggering signal for saccade execution. Thus human neurophysiological data provided evidence both for independent and interdependent processes of saccade preparation and shifts of visual attention.     

Selenoprotein P: recent studies in rats and in humans

Purification of selenoprotein P from rat plasma has allowed detailed characterization of the protein from that species. Chromatographic studies have revealed the existence of at least two isoforms of the protein. One isoform is a truncated protein with termination of protein synthesis occurring at the second selenocysteine codon. Immunohistochemical studies have shown that the rat protein is associated with capillary endothelial cells in the liver, kidney, and brain. In vivo experiments were designed to study the relationship between selenoprotein P and lipid peroxidation. F2 isoprostanes were measured to quantitate the extent of lipid peroxidation caused by diquat. Using selenium-deficient rats supplemented with selenium, it was demonstrated that selenoprotein P appearance correlated with disappearance of diquat-induced lipid peroxidation. This finding is consistent with the protein serving to protect the plasma membrane from oxidative damage. Development of a radioimmunoassay to measure selenoprotein P has allowed assessment of the protein in humans. Measurements of the protein in selenium-deficient Chinese subjects indicated that it can be used as an index of selenium nutritional status in humans.     

Self-consistent model of minority-carrier lifetime, diffusionlength, and mobility

A self-consistent approach is proposed for extracting the minority-carrier mobility from fits to experimental data for lifetime and diffusion length and then comparing the extracted mobility to experimental mobility data. A value for electron and hole lifetime is extracted using a doping-dependent Shockley-Read-Hall mechanism with an Auger process. The hole lifetime is used to extract a minority carrier hole mobility that is consistent with the reported measurements of the hole diffusion length. The good agreement between extracted and experimental mobilities justifies incorporating the results into numerical device and circuit CAD tools     

RF performance of SiC MESFET's on high resistivity substrates

State-of-the art SiC MESFET's showing a record high f_max of 26 GHz and RF gain of 8.5 dB at 10 GHz are described in this paper. These results were obtained by using high-resistivity SiC substrates for the first time to minimize substrate parasitics. The fabrication and characterization of these devices are discussed     

Declining prevalence of cervicovaginal human papillomavirus infection with age is independent of other risk factors

The purpose of this study was to determine whether the addition of small quantities of minor lecithin components (phosphatidylinositol, phosphatidic acid, lysophosphatidylethanolamine, and cholesterol) and Pluronic F68 to lecithin could improve the stability of lecithin-stabilized perfluorocarbon emulsions. Attempts were made to correlate emulsion stability with interfacial properties (tension and charge). Dynamic interfacial tension was determined using a Teflon Wilhelmy plate method [reported previously (1)]. Emulsions were prepared by microfluidization. Microelectrophoresis was used to measure emulsion droplet charge, and photon correlation spectroscopy and Coulter analysis were used to determine emulsion stability as a function of droplet size. Thermal kinetic accelerated stability testing was conducted. Various droplet size parameters were used to compare emulsion stabilities, and an overall stability ranking, based on these parameters, was obtained for each emulsion. Small quantities of additives altered emulsion stability and these data were correlated with interfacial properties and initial droplet diameters. The addition of cholesterol to lecithin resulted in the most stable perfluorocarbon emulsion.     

Oxidation Behaviour of Model Cobalt-Rhenium Alloys During Short-Term Exposure to Laboratory Air at Elevated Temperature

The alloys being used in high-temperature systems such as stationary gas turbines and aircraft engines are iron-, cobalt- and nickel-based superalloys, amongst which the latter is the most widely used for highest temperatures. However, the use of Ni-based alloys is limited to temperatures below 1,100 °C. The experimental Co–Re-based alloys are promising for high-temperature applications for service temperatures beyond 1,200 °C. The purpose of the present investigations, at this still early stage of the alloy development, is to gain a first insight into the oxidation mechanisms and to find ways to improve oxidation resistance of this class of materials. Thermogravimetric studies in combination with microstructural examinations of six model Co–Re alloys with different compositions showed the negative influence of rhenium on the oxidation resistance of Co-based alloys due to evaporation of rhenium oxide(s). Oxidation at 1,000 °C in air yielded an oxide scale, that consists of a Co-oxide outer layer on a thick and porous Co–Cr oxide and a semicontinuous and therefore non-protective Cr-oxide film on the base metal substrate. This allowed for the vaporization of rhenium oxide formed during oxidation and hence led to a loss of Re. Computer-aided thermodynamic calculations were carried out to supplement the experimental analyses and were found to reasonably predict the stability ranges of the various oxide phases observed.     

Ultrastructural characteristics of ovine bone marrow‐derived mesenchymal stromal cells cultured with a silicon stabilized tricalcium phosphate bioceramic

Bioceramics are being used in experimental bone engineering application in association with bone marrow derived mesenchymal stem cells (BM‐MSCs) as a new therapeutic tool, but their effects on the ultrastructure of BM‐MSCs are yet unknown. In this study we report the morphological features of ovine (o)BM‐MSCs cultured with Skelite, a resorbable bioceramic based on silicon stabilized tricalcium phosphate (SiTCP), able to promote the repair of induced bone defect in sheep model. oBM‐MSCs were isolated from the iliac crest, cultured until they reached near‐confluence and incubated with SiTCP. After 48 hr the monolayers were highly damaged and only few cells adhered to the plastic. Thus, SiTCP was removed, and after washing the cells were cultured until they became confluent. Then, they were trypsinizated and processed for transmission electron microscopy (TEM) and RT‐PCR analysis. RT‐PCR displayed that oBM‐MSCs express typical surface marker for MSCs. TEM revealed the presence of electron‐lucent cells and electron‐dense cells, both expressing the CD90 surface antigen. The prominent feature of electron‐lucent cells was the concentration of cytoplasmic organelles around the nucleus as well as large surface blebs containing glycogen or profiles of endoplasmic reticulum. The dark cells had a multilocular appearance by the presence of peripheral vacuoles. Some dark cells contained endocytic vesicles, lysosomes, and glycogen aggregates. oBM‐MSCs showed different types of specialized interconnections. The comparison with ultrastructural features of untreated oBM‐MSCs suggests the light and dark cells are two distinct cell types which were differently affected by SiTCP bioceramic. Skelite cultured ovine BM‐MSCs display electron‐dense and electron‐lucent cells which are differently affected by this bioceramic. This suggests that they could play a different role in bioceramic based therapy.     

Advanced Cold Rolled Steels for Automotive Applications

Advanced high‐strength steels offer a great potential for the further development of automobile bodies‐in‐white due to their combined mechanical properties of high formability and strength. They represent the first choice in material selection for strength and crash‐relevant parts with challenging geometries. The intensive development of multiphase steels by ThyssenKrupp Steel has led to hot dip galvanizing concepts with an outstanding forming potential. Hot rolled, hot dip galvanized complex‐phase steels are currently produced in addition to cold rolled dual phase (DP) and retained austenite (RA) or transformation induced plasticity (TRIP) steels. New continuously annealed grades of steel are being developed with tensile strength levels of up to 1000 MPa in combination with sufficient ductility for the high demands of structural automobile components. These steels make use of the classic advantages of microalloying as well as the principles of DP steels and RA / TRIP steels. Further improvement of properties will be reached by the new class of high manganese alloyed steels.     

Captan residue reduction in apples as a result of rinsing and peeling

Apples, treated with captan for disease control in a commercial orchard in Quebec, Canada, were collected and sorted into post-harvest preparation types (no preparation; rinse; rinse and peel). Captan residues were greatest (25.5–5100 ng/g) in apples with no post-harvest preparation and lowest (0.146–136 ng/g) in apples that had been rinsed and peeled prior to extraction and analysis. Residues were significantly lower (p = 0.003) in apples that had been rinsed prior to extraction than in apples with no post-harvest preparation. Similarly, apples subjected to rinsing and peeling had significantly lower captan residues than had apples that had been rinsed alone (p < 0.0001). Although captan residues in rinsed apples were approximately 50% lower than those in apples that received no post-harvest preparation, the reduction associated with peeling of apples was much greater (98%). Estimated mean captan intakes resulting from consumption of raw apples were established and single day intakes, based on apples with no preparation, ranged from 2.58 μg/kg in females >70 years to 9.48 μg/kg for individuals aged three years (at this age no distinction is made between males and females). Mean intakes estimated using rinsed and peeled apples were approximately two orders of magnitude lower than intakes estimated using apples with no post-harvest preparation, demonstrating the effect of post-harvest preparation on captan intakes. Mean captan intake estimates from all post-harvest preparation types were well below the World Health Organization acceptable daily intake of 100 μg/kg/day, based on raw apple consumption.