Deep traps in GaAs revealed at high resolution by simple fast photocapacitance methods

The characteristics of a new type of capacitance spectroscopy of deep traps in semiconductors are reviewed. A double radiation source technique is employed, the first source controlling the occupation of the traps and the characteristic time constant of the experiment, the second probing the spectral distribution of traps by selectively photoinducing emission to the conduction and valence bands. Time differentiation enhances the detectivity of the traps and minimizes drift problems. Typical spectra obtained with this quasi-equilibrium spectroscopic technique are described. The chromium trap in GaAs presents a distinctive feature with interesting properties which are discussed. Comparisons with thermal capacitance measurements are made, showing the complementary nature of the two methods. The use of the technique to detect out-diffusion of Cr from an insulating substrate into an epitaxial layer is described.     

A 2000 gate 10 n sec uncommitted logic array for telecommunications and computer applications

This paper discusses the development programme used for a VLSI bipolar process for the production of a 2000 Gate ULA.     

Fatty acids induce increased granulocyte macrophage-colony stimulating factor secretion through protein kinase C-activation in THP-1 macrophages

Insulin resistance and type 2 diabetes are associated with elevated circulating levels of nonesterified FA (NEFA) and lipoprotein remnants. The dyslipidemia is an important contributor to the excess arterial disease associated with insulin resistance and type 2 diabetes, but the mechanisms involved are elusive. In the present study we examined the effect of NEFA on macrophages. For this purpose, we utilized human macrophages, prepared by treating THP-1 monocytes with phorbol ester. We found that albumin-bound NEFA at physiological levels increase the secretion of granulocyte macrophage-colony stimulating factor (GM-CSF) by the THP-1 macrophages in a dose-dependent manner. The effect was registered as an increase in mRNA, and the amount of GM-CSF secreted correlated with the accumulation of TAG and DAG in the cell. The NEFA-induced rise in GM-CSF appeared to be mediated by activation of protein kinase C, probably acting on extracellular signal-regulated kinases 1 and 2 and being calcium dependent. We speculate that increased secretion of GM-CSF by resident macrophages in the intima exposed chronically to high levels of NEFA, such as those present in insulin resistance, may contribute to a proatherogenic response of arterial cells.     

Tobacco attributable deaths in South Africa

Background: In mid 1998, a question "Was the deceased a smoker five years ago?" was introduced on the newly revised South African death notification form. Design: A total of 16 230 new death notification forms from 1998 have been coded, and comparison of the prevalence of smoking among those who died of different causes was used to estimate, by case–control comparisons, tobacco attributed mortality in South Africa. Cases comprised deaths from causes known (from other studies) to be causally associated with smoking, and controls comprised deaths from medical conditions expected to be unrelated to smoking. Those who died from external causes, and from diseases strongly related to alcohol consumption, were excluded. Subjects: Reports were available from 5340 deceased adults (age 25+), whose smoking status was given by a family member. Results: Significantly increased risks were found for deaths from tuberculosis (odds ratio (OR) 1.61, 95% confidence interval (CI) 1.23 to 2.11), chronic obstructive pulmonary disease (COPD) (OR 2.5, 95% CI 1.9 to 3.4), lung cancer (OR 4.8, 95% CI 2.9 to 8.0), other upper aerodigestive cancer (OR 3.0, 95% CI 1.9 to 4.9) and ischaemic heart disease (OR 1.7, 95% CI 1.2 to 2.3). Conclusion: If smokers had the same death rate as non-smokers, 58% of lung cancer deaths, 37% of COPD deaths, 20% of tuberculosis deaths, and 23% of vascular deaths would have been avoided. About 8% of all adult deaths in South Africa (more than 20 000 deaths a year) were caused by smoking.     

Reconstruction and quantification of the carotid artery bifurcation from 3-D ultrasound images

Three-dimensional (3-D) ultrasound is a relatively new technique, which is well suited to imaging superficial blood vessels, and potentially provides a useful, noninvasive method for generating anatomically realistic 3-D models of the peripheral vasculature. Such models are essential for accurate simulation of blood flow using computational fluid dynamics (CFD), but may also be used to quantify atherosclerotic plaque more comprehensively than routine clinical methods. In this paper, we present a spline-based method for reconstructing the normal and diseased carotid artery bifurcation from images acquired using a freehand 3-D ultrasound system. The vessel wall (intima-media interface) and lumen surfaces are represented by a geometric model defined using smoothing splines. Using this coupled wall-lumen model, we demonstrate how plaque may be analyzed automatically to provide a comprehensive set of quantitative measures of size and shape, including established clinical measures, such as degree of (diameter) stenosis. The geometric accuracy of 3-D ultrasound reconstruction is assessed using pulsatile phantoms of the carotid bifurcation, and we conclude by demonstrating the in vivo application of the algorithms outlined to 3-D ultrasound scans from a series of patient carotid arteries.     

High-throughput comprehensive analysis of human plasma proteins: a step toward population proteomics

A high-throughput (HT) comprehensive analysis approach was developed for assaying proteins directly from human plasma. Proteins were selectively retrieved, by utilizing antibodies immobilized within affinity pipet tips, and eluted onto enzymatically active mass spectrometer targets for subsequent digestion and structural characterization. Several parameters, including uniform parallel protein elution from 96 affinity pipet tips, proper buffering for on-target digestion, termination of the digestion, and MALDI matrix (re)introduction, were evaluated and optimized. The approach was validated via parallel, high-throughput analysis of transthyretin (TTR) and transferrin (TRFE) from 96 identical plasma samples. The 96 parallel analyses for each protein were completed in less than 90 min, measured from protein extraction to insertion in the mass spectrometer. Virtually identical mass spectra were obtained from the 96 TTR analyses, characterized by the presence of 14 tryptic fragments that allowed TTR sequence mapping with 100% coverage. Database search returned TTR as the best match for all 96 data sets. In regard to the TRFE analyses, database searching using data from the 96 spectra returned TRFE as the best match for all but 1 of the spectra. TRFE was mapped with 47-69% sequence coverage, with gaps in the sequence coverage corresponding to the carbohydrate-containing peptide fragments and large and small trypsin fragments that fell outside the window of mass analysis. Overall, the combined high-throughput affinity capture-protein digestion approach showed high reproducibility and speed and yielded an exceptional level of protein characterization, suggesting its use in future population proteomics endeavors.     

Quantitative determination of heme for forensic characterization of bacillus spores using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

A quantitative method was developed for the determination of heme (ferriprotoporphyrin IX) using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). The method was designed for forensic characterization of the use of blood agar in preparation of Bacillus spores. An alkali wash of 0.3 M ammonium hydroxide was used to solubilize heme from spore samples. The wash was concentrated and analyzed by MALDI-TOFMS. Experimental parameters were optimized to obtain the best signal intensity, maximize signal reproducibility, and improve day-to-day repeatability of the measurement. Sinapinic acid was found to be the best matrix. A sandwich sample preparation protocol was determined to increase the shot-to-shot and point-to-point reproducibility of the measurement. Cobalt(III) protoporphyrin was used as an internal standard and the analyte/internal standard ratio responses from solutions of known concentrations were used to construct a calibration curve (R(2) = 0.993). Limits of detection and quantitation for heme were calculated to be approximately 0.4 (200 fmol) and 0.8 microM (400 fmol), respectively. Spore samples prepared on blood agar and nonblood agar were analyzed using the method. Heme was detected at a concentration of approximately 0.3 ng/mg of spore on samples prepared on blood agar and purified by extensive washing. Heme was not detected on spore samples prepared without blood.     

Pore closure models for gas-solid reactions: The effect of bulk flow and reversibility

A pore closure model of gas-solid reactions has been extended to include the effect of bulk flow and reversible reactions. Both effects are shown to be of major importance in the chlorination of magnesia. During the course of reaction the controlling resistance is shown to change from pore diffusion to product layer diffusion to pore diffusion caused by closure of the pore.     

"Development of Time, Speed, and Distance Concepts": Correction to Siegler and Richards.

Reports an error in the original article by Robert S. Siegler and D. Dean Richards (Developmental Psychology, 1979, Vol. 15[3], pp. 288-298). The column headings of Table 1 on p. 291 are incorrect. Each pair of lines in the column headings represents the starting points, stopping points, and total distance traveled by the trains. The corrected table appears below. (The following abstract of this article originally appeared in record 1979-28311-001.) Used the rule-assessment approach to examine understanding of the concepts of time, speed, and distance in 36 5-, 8-, and 11-yr-olds and 12 undergraduates. Parallel tasks were developed for the 3 concepts that allowed specification of whether Ss were relying on time, speed, distance, end point, end time, beginning point, or beginning time cues in making their judgments. It was found that 5-yr-olds understood all 3 concepts in the same way: Whichever train ended farther ahead on the tracks was said to have traveled for the longer time, at the faster speed, and for the greater distance. Undergraduates, at the other extreme, understood all 3 concepts as distinct and separate ideas. The transitional period was marked by specific confusions among the 3 concepts: Time was regularly confused with distance, distance was confused with time, and speed was confused with distance and to some extent with end point. Both speed and distance concepts appeared to be mastered well before the concept of time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)