An electrical network approach to the analysis of semiconductordevices

A simple electrical network is used to represent the five differential equations describing basic phenomena in one-dimensional semiconductor devices. Both standard and integrated approaches for solving transport equations are developed. Also, an electrical network equivalent for the nonlinear Poisson equation was derived. It allows students to better understand the physical phenomena and the process of computer simulation of such semiconductor devices     

Using spreadsheets in introductory EE courses

Ways in which spreadsheet programs can be used to introduce practical considerations in introductory electrical engineering courses are discussed. Examples are presented which show that spreadsheets can be used to predict and/or minimize the errors due to loading, the availability of only standard resistor values, and resistor tolerances. The circuits considered in these examples were selected to be as simple as possible. These examples could be used in the first semester of sophomore credits. They illustrate trade-offs, performance criteria, and nonunique solutions, and are intended to illustrate the power of spreadsheet programs. In the first example, a macro is used to implement a simple iterative optimization procedure. In the second example, minimization is done by exhaustive search using the table lookup capabilities of the spreadsheet. In the final example, the spreadsheet's random number generator is used to perform a Monte Carlo analysis     

Hierarchical intelligent control with flexible AC transmission systems application

A novel hierarchical intelligent controller configuration is proposed using an artificial neural network as a control-mode classifier in the supervisory level and a set of pre-designed controllers in the lower level. Controller outputs are modified nonlinearly by the classifying signals in a structure resembling one artificial neuron with adaptively changed weights. The lower-level local controllers are implemented using neural networks. An illustrative example of this approach is based on the transient stabilization of a single-machine infinite-bus system studied in Flexible AC Transmission Systems (FACTS) research.     

Comparative autoradiographic distribution of central omega (benzodiazepine) modulatory site subtypes with high, intermediate and low affinity for zolpidem and alpidem

Pharmacological characterization of [3H]benzodiazepine binding to membrane preparations of adult rat hippocampus and neonatal rat brain have demonstrated, in addition to the omega 1 and omega 2 populations of central omega benzodiazepine binding sites associated with GABAA receptors, the existence of binding sites with microM affinity for the imidazopyridines zolpidem and alpidem. In the present study we have investigated their comparative autoradiographic distribution using [3H]flumazenil as a ligand. In the neonatal rat CNS, the imidazopyridine derivatives zolpidem and alpidem were found to discriminate two [3H]flumazenil binding site populations with an IC50 value ratio of more than 200-fold. In the different regions investigated (spinal cord, striatum, neocortex and inferior colliculus) the low affinity component had IC50 values of 20-40 microM (zolpidem) and 5-15 microM (alpidem) and accounted for ca. 50% of the total binding site population. In the adult rat, these imidazopyridine derivatives displayed a greater displacing potency in the cerebellum (IC50 = 6 and 36 nM, respectively) than in the hippocampus (IC50 = 37 and 403 nM, respectively). In the cerebellum, [3H]flumazenil binding was fully displaced by 1 microM of either compound and Hill coefficients of displacement curves were close to unity. In the hippocampus, 25% of [3H]flumazenil binding were resistant to 3 microM zolpidem or 1 microM alpidem, but were displaced by 100 microM of either compound. CL 218,872 also displayed a greater displacing potency in the cerebellum (IC50 = 83 nM) than in the hippocampus (IC50 = 711 nM) but [3H]flumazenil binding in the hippocampus was fully displaced by 10 microM of this compound. In adult rat hippocampus, zolpidem and alpidem were found to discriminate between three central omega site subtypes which display high (IC50 = 31 and 6.1 nM, for these imidazopyridine derivatives. In contrast, CL 218,872 discriminated between omega 1 and omega 2 sites but not between two omega 2 receptor subpopulations. omega 1 sites were mainly localized in layer IV of the sensorimotor cortex, cerebellum, substantia nigra, olfactory bulb and inferior colliculus. omega 2I sites were present in the cortical mantle (with higher levels in the cingulate and olfactory than in the sensorimotor cortex) and in subcortical (hippocampus, hypothalamus and nucleus accumbens) limbic structures. In the hippocampus, hypothalamus, spinal cord and nucleus accumbens, omega 2L sites accounted for more than 25% of the specific [3H]flumazenil binding; the density of these sites was minor in the cortex and in most pyramidal and extrapyramidal system structures.(ABSTRACT TRUNCATED AT 400 WORDS)     

Activity of quinolones in the Ames Salmonella TA102 mutagenicity test and other bacterial genotoxicity assays

Eight quinolones were examined for their bacterial mutagenicity in the Ames Salmonella TA102 assay and for their effects in other bacterial genotoxicity assays. In the quantitative Ames plate incorporation assay, all eight quinolones induced His+ deletion reversion in Salmonella tester strain TA102, with maximum reversion observed at about two to eight times the MIC. The quinolones also induced the SOS response. At quinolone concentrations close to the MIC, SOS cell filamentation gene sulA was induced in sulA::lacZ fusion strain Escherichia coli PQ37. RecA-mediated cleavage of lambda repressor in lambda::lacZ fusion strain E. coli BR513 was measurable at about 10 times the MIC, though no induction occurred at 20 micrograms of nalidixic or oxolinic acid per ml. Genotoxicity of quinolones also was observed in the Bacillus subtilis DNA repair assay, in which the mutant strain M45 (recA) was more susceptible to quinolones than its parent strain, H17 (rec+). The results from these analyses indicate that quinolones induce SOS functions and are mutagenic in bacteria; these properties correspond to their antimicrobial activities.     

The dimensions underlying perceived attitudes: Liberalism and concern for traditional values.

Two studies identified and labeled the dimensions that people use to judge others' attitudes. In the 1st study, 50 male and 50 female undergraduates viewed pairs of attitude statements drawn from 1 or 2 large sets. For each pair of statements, Ss judged whether or not a person who agreed with one statement in the pair would be likely to agree with the other. The dimensions of liberalism and traditional values were found to underlie perceived attitudes. Validity was confirmed in a 2nd study with 60 male and 60 female undergraduates who rated the characteristics of hypothetical people who agreed strongly with particular statements. Results suggest that there is a common structure to people's perceptions of others' attitudes. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Work-site smoking policies: their population impact in Washington State

This article presents data from a population-based, random-digit dialing telephone survey of 1228 employed adults in Washington State, conducted 1989 through 1990. Eighty-one percent of men and 91% of women reported work-site smoking restrictions. Employees in work sites with no-smoking policies were less likely to be current smokers; men in work sites with policies restricting smoking smoked fewer cigarettes on both workdays and nonworkdays. Forty-eight percent of male and 53% of female smokers reported reduced smoking as a result of work-site policy. Work-site smoking policies, intended to protect against smoke exposure, may also reduce employee smoking.