Establishment of accuracy limits and standards for comparative thermal conductivity measurements

New techniques have been developed for reducing thermal conductivity data from thermal comparative measurements. The first of these techniques is based on making a Taylor-series expansion of the stack centerline temperature profile. The result is an expression giving the ratio of sample to reference conductivities at any temperature as a function of measured quantities, the stack thermocouple readings and stack element thicknesses. The conventional formula presently used to reduce comparative conductivity data is shown to be a special result of the general analysis. A second technique involves the use of linear least-squares (LS) techniques to derive both the sample and the reference conductivities from the measured data. The LS technique provides the coefficients for a polynomial temperature expansion of the reference and sample conductivities directly. Use of the new techniques is illustrated in a reduction of some comparative data on the conductivities of Pyrex 7740 and Pyroceram 9606. It is shown that a highly self-consistent pair of conductivity functions can be derived for these two commonly used reference materials if the conductivity vs temperature relation for Pyrex is modified slightly from its recommended value. The Pyroceram conductivity results from the comparative measurements are in good agreement with a conductivity derived from pulse diffusivity and differential scanning calorimetry measurements and also in good agreement with the recommended Pyroceram conductivity function.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

Discrepancy between predicted and obtained WAIS–R IQ scores discriminates between traumatic brain injury and insufficient effort.

This study examines how well the discrepancy between predicted and obtained Wechsler Adult Intelligence Scale–Revised (WAIS–R) scores discriminate between insufficient effort (IE) and traumatic brain injury (TBI). The 27 IE patients performed significantly more poorly on the WAIS–R than the 48 moderate-severe TBI patients. Premorbid IQs were calculated with formulae that use demographics (Barona Index) or demographics and WAIS–R performance (Best-3 and the Oklahoma Premorbid Intelligence Estimation). Predictions were similar on the Barona, but IE patients' predicted IQs were lower than TBIs for measures with a performance component. IE patients demonstrated a greater discrepancy score (i.e., predicted IQ—obtained IQ) than TBIs; variable levels of sensitivity and specificity were obtained when discriminate functions were developed on these scores. The potential advantage of using discrepancy scores versus performance-based measures to detect insufficient effort is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Diagnostic validity of the Luria-Nebraska Neuropsychological Battery—Children's Revision.

Compared the diagnostic validity of the Luria-Nebraska Neuropsychological Battery—Children's Revision (LNNB—C) and the Wechsler Intelligence Scale for Children—Revised (WISC—R) for 96 8–12 yr olds in 1 of 3 diagnostic groups: neurological, psychiatric, and normal controls. Interrater reliability was demonstrated. Separate stepwise discriminant analyses using 6 variables (subtest scores) selected by each test correctly classified 81% (LNNB—C) and 85% (WISC—R) of the psychiatric and neurological groups. No clear incremental validity for the use of the LNNB—C over the WISC—R was demonstrated. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Performance analysis of the segment npn anode LIGBT

The performance of a high-voltage lateral insulated gate bipolar transistor (LIGBTs) with segmented n+p/n anode fabricated in junction isolation technology is experimentally investigated at both room and elevated temperatures. Detailed two dimensional numerical modeling of a vertical representation of the structure shows that significant electron current passes through the n/sup +/p/n segment of the anode region during the on-state and when devices are subjected to clamped inductive switching. It is shown that the magnitude of electron current can be controlled by modifying the p-base charge which enables enhancement of the turn-off loss/forward voltage drop tradeoff in comparison to conventional LIGBTs.     

Innovation in power semiconductor industry: past and future

Power microelectronics plays an important role in many of the consumer and industrial applications today. With increase in demand for energy savings and efficient systems, the requirements for rapid advancement in MOS controlled power semiconductor device concepts and technologies are becoming more crucial than ever before. This puts a considerable pressure on industries to be innovative and competitive at the device, technology, manufacturing, and marketing levels. Today manufacturing companies are faced with intensifying competition and a turbulent economic environment. To some extent technology is seen as a means by which firms can strive to adapt to the requirements of this difficult and uncertain environment. On the other hand, rapid rates of technological change and associated shorter product cycles are themselves part of the difficulty, as is the increased blurring of long-established industrial boundaries (Kodama's, 1985) process of "technological fusion". The growing complexity and increased pace of industrial technological change especially in power microelectronics are forcing firms to forge new alliances and to seek greater flexibility and efficiency in responding to market changes. The aim of this paper is to explore these aspects.     

Bacterial lipopolysaccharide confers resistance to G418, doxorubicin, and taxol in the murine macrophage cell line, RAW264

Many bacterial pathogens including Salmonella and Listeria replicate within macrophages. The susceptibility of these organisms to various antibiotics is dependent on the ability of macrophages to take up, retain, and deliver the antibiotic to the correct intracellular compartment. In this context, macrophages are known to express proteins that are involved in efflux of antibiotics and cytotoxic drugs, thereby reducing intracellular accumulation of such compounds. In our studies on the action of bacterial lipopolysaccharide (LPS) on the macrophage-like cell line, RAW264 we found that LPS treatment of these cells conferred resistance to the neomycin-related aminoglycoside G418 (geneticin). This phenotype was stable and was specific to LPS since colony-stimulating factor 1 and phorbol myristate acetate had no effect on G418 resistance. We have extended this observation to show that LPS induces transient resistance to the cytotoxic drugs taxol and doxorubicin. Macrophage resistance to cytotoxic drugs and antibiotics may have a number of important clinical consequences.     

Electrophysiological and pharmacological responses of chronically denervated lower esophageal sphincter of the opossum

BACKGROUND & AIMS: Achalasia is characterized by loss of myenteric neurons and incomplete relaxation of the lower esophageal sphincter (LES). The aim of this study was to develop an achalasia model in the opossum using the surfactant benzyldimethyltetradecylammonium chloride (BAC). This study further characterizes the achalasia model. METHODS: BAC or saline was injected circumferentially into the LES of 14 adult opossums. Eight months after injection, manometry, isolated muscle bath studies, electrical field stimulation, and histochemical analysis were performed. RESULTS: Manometrically, the LES of BAC-treated opossums showed higher pressures (38.7 +/- 12 mm Hg vs. 17 +/- 3.0 mm Hg) and reduced esophageal body contraction amplitudes (4.2 +/- 3 mm Hg vs. 27.4 +/- 12 mm Hg). Isolated muscle strips challenged with carbachol and sodium nitroprusside contracted and relaxed similarly to controls. Electrical field stimulation failed to induce relaxation in BAC-treated tissue but did induce contraction. Contractile responses were markedly reduced by tetrodotoxin and atropine in BAC-treated animals and controls. An altered nitric oxide system was shown by the lack of response to L-arginine and N omega-nitro-L-arginine. Histology showed loss of myenteric neurons and increased cholinergic nerve bundles. CONCLUSIONS: Loss of NO inhibitory myenteric neurons markedly reduces the relaxation of the LES, and histology and pharmacological responses suggest a proliferation of cholinergic nerves into the LES contributing to the static elevated pressures of the amyenteric LES.     

Evaluation of Wechsler Adult Intelligence Scale—Revised premorbid IQ formulas in clinical populations.

The use of demographic variables in the prediction of premorbid IQ has been noted to show some promise (R. S. Wilson et al; see record 1979-26429-001). With the revision of the Wechsler Adult Intelligence Scale (WAIS—R) and subsequent development of a regression formula for the WAIS—R (A. Barona et al; see record 1985-04035-001), some authors have suggested that continued use of the Wilson formulas is inappropriate. The present study examined the efficacy of both Wilson and Barona formulas in the prediction of concurrently obtained IQ levels in neurologically normal psychiatric (n?=?77) and brain-damaged (n?=?64) patients. The results demonstrated that neither formula differed significantly in terms of classifications of IQ range, with both formulas performing essentially at chance levels. Qualitative and quantitative differences between the formulas are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Active Control With an Isoluminant Display

Humans perceive isoluminant visual stimuli (i.e., stimuli that show little or no luminance variation across space) to move more slowly than their luminance-defined counterparts. To explore whether impaired motion perception at isoluminance also affects visuomotor control tasks, the authors examined the performance as humans actively controlled a moving line. They tested two types of displays matched for an overall salience: a luminant display composed of a luminance-defined Gaussian-blurred horizontal line and an isoluminant display composed of a color-defined line with the same spatial characteristics, but near-zero luminance information. Six subjects were asked to use a joystick to keep the line centered on a cathode ray tube display as its vertical position was perturbed pseudorandomly by a sum of ten sinusoids under two control regimes (velocity and acceleration control). The mean root mean square position error was larger for the isoluminant than for the luminant line (mean across subjects: 22% and 29% larger, for the two regimes, respectively). The describing functions (Bode plots) showed that, compared to the luminant line, the isoluminant line showed a lower open-loop gain (mean decrease: 3.4 and 2.9 dB, respectively) and an increase in phase lag, which can be accounted for by an increase in reaction time (mean increase: 103 and 155 ms, respectively). The performance data are generally well fit by McRuer's classical crossover model. In conclusion, both our model-independent and model-dependent analyses show that the selective loss of luminance information impairs human active control performance, which is consistent with the preferential loss of information from cortical visual motion processing pathways. Display engineers must therefore be mindful of the importance of luminance-contrast per se (not just total stimulus salience) in the design of effective visual displays for closed-loop active control tasks     

Phase formation and texture of nickel silicides on Si1−xCx epilayers

We investigated the phase formation and texture of nickel silicides formed during the reaction of 10 nm sputter deposited nickel with Si_1−xC_x epitaxial layers on Si(1 0 0) substrates, having a carbon content between 0 and 2.5 atomic percent. It was found that both the formation temperature as well as the texture of the metal-rich phases is influenced by the amount of carbon in the Si_1−xC_x layer. To determine the influence of the location of the carbon during the silicidation process we also investigated the reaction of 10 nm nickel on Si(1 0 0) substrates, where carbon was either alloyed in the nickel layer or deposited as an interlayer at the interface between the nickel and the substrate. Depending on the location of the carbon, a different thermal stability of the layer was found.