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1

August 28, 2003: Critical Sulfhydryl Switches, Diet, and Cancer Prevention Workshop - Speakers List  

Cancer.gov

Critical Sulfhydryl Switches, Diet, and Cancer Prevention Workshop Speakers List Elizabeth H. Jeffery, Ph.D., Chair Professor Nutritional Sciences Research Group Division of Cancer Prevention National Cancer Institute National Institutes of Health

2

August 28, 2003: Critical Sulfhydryl Switches, Diet, and Cancer Prevention Workshop; Bethesda, MD  

Cancer.gov

Critical Sulfhydryl Switches, Diet, and Cancer Prevention Workshop Meeting Date August 28, 2003 Meeting Location Bethesda Marriott Hotel Bethesda, MD Meeting Materials Agenda Executive Summary (pdf, 96kb) Attendee List (pdf, 1kb) Speakers List

3

August 28, 2003: Critical Sulfhydryl Switches, Diet, and Cancer Prevention Workshop - Attendee List  

Cancer.gov

Prevention Workshop Attendee List Elizabeth H. Jeffery, Ph.D., Chair Professor Nutritional Sciences Research Group Division of Cancer Prevention National Cancer Institute National Institutes of Health Bethesda, Maryland Daniel E.

4

Ligand-promoted oligomerization and sulfhydryl modification of biodegradative L-threonine dehydratase of Escherichia coli  

E-print Network

of Enzyme Activity 39 Ligand Effects on The Stoichiometry of The DTNB Modification of Biodegradative L-Threonine Dehydratase. . . 44 Effects of Sulfhydryl Modification by NEM on the Catalytic Parameters Xm and Vmax. Sulfhydryl Modification and 5-'AMP... of cell function, which refers to the switching on and off of metabolic processes usually via the second messenger cAMP . 3. Allosteric control of regulatory enzymes which refers to the regulation of enzyme activity via protein-ligand interactions...

Cardozo, Luisa Elena

2012-06-07

5

Deciding when to switch tasks in time-critical multitasking Action editor: Christian Schunn  

E-print Network

Deciding when to switch tasks in time-critical multitasking Action editor: Christian Schunn Yelena switching in laboratory-task settings. In contrast, many real-world complex tasks, particularly time­49 www.elsevier.com/locate/cogsys #12;resources, at the time when switching between tasks takes place

Salvucci, Dario D.

6

Deciding When to Switch Tasks in Time-Critical Multitasking Yelena Kushleyeva (yk45@drexel.edu)  

E-print Network

Deciding When to Switch Tasks in Time-Critical Multitasking Yelena Kushleyeva (yk45@drexel focus on externally-driven task switching in laboratory-task settings. In contrast, many real the person her/himself decides when to switch between tasks. In this paper we propose an adaptation

Salvucci, Dario D.

7

A critical role for the right fronto-insular cortex in switching between central-executive and  

E-print Network

A critical role for the right fronto-insular cortex in switching between central with activation of a third network comprising the right fronto-insular cortex (rFIC) and anterior cin- gulate, plays a critical and causal role in switching between the CEN and the DMN. We replicated this causal

Allman, John M.

8

Critical switching impulse strength of phase-to-phase air insulation  

Microsoft Academic Search

The paper presents a new physical approach to modelling of positive leader inception and breakdown of phase-to-phase insulation in air, exposed to critical switching impulses of synchronized peaks and opposite polarity. The work constitutes a generalization of a recently published model dealing with phase-to-ground insulation and covers both conductor-conductor and horizontal rod-rod configurations. The influence of interphase separation, conductor height

F. A. M. Rizk

1993-01-01

9

Critical slowing down in polarization switching of vertical-cavity surface-emitting lasers  

NASA Astrophysics Data System (ADS)

This research investigated the critical slowing down in polarization switching (PS) of vertical-cavity surface-emitting lasers (VCSELs). The experiments were performed by step-function current injection in two types: step-up and stepdown. In the case of step-up and step-down, the relationship between relaxation time and final current in this experiment resembles critical slowing down (CSD). The critical currents of two step-function current experiment are compared. The PS in this experiment is a static case. We also find that the divergence of relaxation time follow a power law. These results contribute to the understanding of the mechanism of CSD in VCSEL's PS (VPS).

Wu, Yu-Heng; Li, Yueh-Chen; Kuo, Wang-Chuang; Yen, Tsu-Chiang

2014-05-01

10

Critical switching impulse strength of phase-to-phase air insulation  

SciTech Connect

The paper presents a new physical approach to modelling of positive leader inception and breakdown of phase-to-phase insulation in air, exposed to critical switching impulses of synchronized peaks and opposite polarity. The work constitutes a generalization of a recently published model dealing with phase-to-ground insulation and covers both conductor-conductor and horizontal rod-rod configurations. The influence of interphase separation, conductor height above ground, conductor radius and relative amplitude of the negative impulse on critical insulation strength is systematically investigated. A novel application of the model is a physically based prediction of air density effects on phase-to-phase leader inception and breakdown. The model findings are extensively compared with experimental results.

Rizk, F.A.M. (Inst. de recherche d'Hydro-Quebec, Varennes (Canada))

1993-07-01

11

Critical analysis and remedy of switching failures in straintronic logic using Bennett clocking in the presence of thermal fluctuations  

NASA Astrophysics Data System (ADS)

Straintronic logic is a promising platform for beyond Moore's law computing. Using Bennett clocking mechanism, information can propagate through an array of strain-mediated multiferroic nanomagnets, exploiting the dipolar coupling between the magnets without having to physically interconnect them. Here, we perform a critical analysis of switching failures, i.e., error in information propagation due to thermal fluctuations through a chain of such straintronic devices. We solved stochastic Landau-Lifshitz-Gilbert equation considering room-temperature thermal perturbations and show that magnetization switching may fail due to inherent magnetization dynamics accompanied by thermally broadened switching delay distribution. Avenues available to circumvent such issue are proposed.

Roy, Kuntal

2014-01-01

12

Caveolin-1 Is a Critical Determinant of Autophagy, Metabolic Switching, and Oxidative Stress in Vascular Endothelium  

PubMed Central

Caveolin-1 is a scaffolding/regulatory protein that interacts with diverse signaling molecules. Caveolin-1null mice have marked metabolic abnormalities, yet the underlying molecular mechanisms are incompletely understood. We found the redox stress plasma biomarker plasma 8-isoprostane was elevated in caveolin-1null mice, and discovered that siRNA-mediated caveolin-1 knockdown in endothelial cells promoted significant increases in intracellular H2O2. Mitochondrial ROS production was increased in endothelial cells after caveolin-1 knockdown; 2-deoxy-D-glucose attenuated this increase, implicating caveolin-1 in control of glycolytic pathways. We performed unbiased metabolomic characterizations of endothelial cell lysates following caveolin-1 knockdown, and discovered strikingly increased levels (up to 30-fold) of cellular dipeptides, consistent with autophagy activation. Metabolomic analyses revealed that caveolin-1 knockdown led to a decrease in glycolytic intermediates, accompanied by an increase in fatty acids, suggesting a metabolic switch. Taken together, these results establish that caveolin-1 plays a central role in regulation of oxidative stress, metabolic switching, and autophagy in the endothelium, and may represent a critical target in cardiovascular diseases. PMID:24498385

Sugiyama, Toru; Sartoretto, Juliano L.; Kalwa, Hermann; Yan, Zhonghua; Shimokawa, Hiroaki; Michel, Thomas

2014-01-01

13

[Estimation of sulfhydryl groups by laboratory titrator T-201].  

PubMed

A method for estimating sulfhydryl groups by laboratory titrator T-201 is proposed. It consists in culonometric titration of SH-groups by silver ions. The method is highly sensitive and reproducible. PMID:7378573

Aleksidze, N G; Koshoridze, N I

1980-01-01

14

Modification of membrane sulfhydryl groups in bacteriostatic action of nitrite  

SciTech Connect

The mechanism by which nitrite inhibits outgrowing spores of bacillus cereus T was examined by using techniques developed earlier for nitrite analogs. The morphological stage of inhibition, cooperativity effects, effect of pH on inhibition, kinetics of protection against tritiated iodoacetate incorporation into membrane sulfhydryl groups, and protection against the bacteriocidal effect of carboxymethylation of iodoacetate indicate that nitrite acts as a membrane-directed sulfhydryl agent. The mechanism by which nitrite modifies the chemical reactivity of the sulfhyrdyl group could be either direct covalent modification or inactivation through communication with another modified membrane component. Profiles of pH effects suggest that the active agent is the protonated form of nitrite. The nitrite concentrations which modify membrane sulfhydryl activity coincide with those which have a bacteriostatic effect. These results are consistent with membrane sulfhydryl modification as a component of the mechanism of nitrite-induced bacteriostasis in this aerobic sporeformer.

Buchman, G.W. III; Hansen, J.N.

1987-01-01

15

Interaction of pantetheinase with sulfhydryl reagents and disulfides.  

PubMed

The effect of many thiol reagents and disulfides on pantetheinase (E.C. 3.5.1.-; pantetheine hydrolase) was studied in the presence or absence of S-pantetheine-3-pyruvate as substrate. Iodoacetamide, iodoacetate, bromopyruvate and N-ethylmaleimide irreversibly inactivate the enzyme at very different rates. Inactivation constants, corrected for the different reactivity of halogeno derivatives with non-protein thiols, suggest the presence of an essential sulfhydryl group in the enzyme and a negatively charged environment near this group. p-Chloromercuribenzoate is the most effective inhibitor; 2-nitro-5-thiocyanobenzoate, o-iodosobenzoate and hydrogen peroxide give a biphasic inhibition pattern, indicating the existence of two sulfhydryl groups whose modification affects activity. Organic arsenicals decrease activity to about 50%. Neutral and positively charged disulfides are effective inhibitors. Substrate protects the enzyme from inactivation, except in the case of negatively charged disulfides, where the presence of substrate enhances the inhibitory effect. Titration with Ellman's reagent or 4,4'-dithiodipyridine under various experimental conditions demonstrated the existence of two sulfhydryls and three disulfides in the fully active enzyme. Pantetheinase may become inactive during purification with concomitant loss of one titrable sulfhydryl group. PMID:3753883

Ricci, G; Nardini, M; Chiaraluce, R; Duprè, S; Cavallini, D

1986-03-01

16

High Speed Spin-Transfer Switching Behavior of Low Critical Current Spin Valve Nanopillars  

NASA Astrophysics Data System (ADS)

For spin transfer writing to be effective for MRAM, the integration of a magnetic device with a scaled CMOS transistor in a memory cell requires that Ic for switching a thin, thermally stable element on ns time scales be << 1 mA. Since Ic scales with the volume of the magnetic element and the square of its saturation magnetization MS, the use of very small free layers with low MS can result in low Ic's. The challenge is obtaining a large enough magnetic anisotropy to ensure thermal stability at ˜100 C. We have fabricated 40x120 nm elliptical Py/Cu/Py nanopillar spin valves exhibiting free layer coercive fields in accord with 3-D micromagnetic modeling. For a 4.5 nm thick free layer device, currents necessary for 100% switching go from 0.6 mA for a 10 ns pulse, where thermal activation aids switching, to 2 mA for a 1 ns pulse, where there is insufficient time for thermal fluctuations and Ic is set by the current required to transfer enough spin into the free layer to force its reversal. We will discuss the switching mechanisms of these devices in the ns regime, and our progress towards achieving fully stable devices with low Ic's.

Braganca, P. M.

2005-03-01

17

Adverse effects profile of sulfhydryl compounds in man.  

PubMed

Many of the adverse reactions produced by penicillamine and other compounds with an active sulfhydryl group form a distinctive pattern when viewed as a class. Alterations in taste perception, mucocutaneous lesions, proteinuria due to immune-complex membranous glomerulopathy, and pemphigus are adverse reactions that have been encountered with all of the compounds discussed herein. Hematologic reactions such as neutropenia and thrombocytopenia occur rarely and with variable frequency. The angiotension converting enzyme inhibitor captopril has an active sulfhydryl group. When it was first given in high doses to patients with severe hypertension, adverse effects similar in pattern to those just outlined were reported. With reduced doses and more careful patient selection, the more serious reactions are no longer found, but disturbances of taste perception, rash, and oral mucosal ulcers are still encountered. PMID:2937293

Jaffe, I A

1986-03-01

18

Nonfunctional nature of sulfhydryl groups for pigeon liver malic enzyme.  

PubMed

The cyanylated derivative of pigeon liver malic enzyme (EC 1.1.1.40) may be prepared by reacting the sulfhydryl groups of the enzyme with 2-nitro-5-thiocyanobenzoic acid in the presence of excess KCN or by replacing the thionitrobenzoate moiety of the thionitrobenzoated enzyme with CN group. The -SCN derivative thus prepared is enzymatically active and is resistant to react with the affinity label bromopyruvate. In the generation of -SCN enzyme from the thionitrobenzoated enzyme, there is a correlation between the [14C] CN incorporation and the activity recovered. The sulfhydryl groups are thus not directly involved in the catalytic mechanism of the malic enzyme. Evidence is also provided to show that the SH groups were not involved in the binding of nucleotide coenzyme. PMID:7461912

Chang, G G; Chueh, S H

1980-10-01

19

THIOL-BASED REGULATORY SWITCHES  

Microsoft Academic Search

? Abstract Thiol-based regulatory switches play central roles in cellular responses to oxidative stress, nitrosative stress, and changes in the overall thiol-disulfide redox balance. Protein sulfhydryls offer a great deal of flexibility in the different types of modification they can undergo,and the range of chemical,signals they can perceive. For example, recent work on OhrR and OxyR has clearly established that

Mark S. B. Paget; Mark J. Buttner

2003-01-01

20

A new hybridocytochemical method based on mercurated nucleic acid probes and sulfhydryl-hapten ligands  

Microsoft Academic Search

In the preceding paper, a method to detect specific DNA sequences with mercurated nucleic acid probes and sulfhydryl-hapten ligands has been described. Due to the instability of the bond between mercury and a negatively charged sulfhydryl-hapten ligand (trinitrophenyl-glutathione), the in situ formed hybrid could not be detected. On basis of model system experiments it was suggested that this mercury-sulfhydryl bond

A. H. N. Hopman; J. Wiegant; P. Duijn

1986-01-01

21

Probing the active site of the reconstituted carnitine carrier from rat liver mitochondria with sulfhydryl reagents. A cysteine residue is localized in or near the substrate binding site.  

PubMed

The interaction of sulfhydryl reagents with the carnitine carrier of rat liver mitochondria was studied in detail in proteoliposomes. The addition of N-ethylmaleimide, mercurials at low concentrations, Cu(2+)-phenanthroline and diamide modified a single sulfhydryl group (the class II group) that is involved in transport function. The treatment of the inhibited protein with 1,4-dithioerythritol led to full recovery of carnitine exchange except for N-ethylmaleimide. Evidence is provided that the addition of carnitine to the carrier blocks the interaction of the sulfhydryl reagents with the protein. This result strongly suggests that the critical cysteine residue is localized in, or near, the substrate binding site. Interaction of other cysteine residues in the carrier protein with high concentrations of mercurials modified another class of sulfhydryl groups (the class I group) that are not directly involved in carnitine transport. The oxidized and reduced forms of the carnitine carrier show slightly different molecular masses on SDS/PAGE. Disulfide bridge(s) induced by Cu(2+)-phenanthroline and diamide are present in a single polypeptide part of the protein and induced no disulfide bridges between two polypeptide chains. PMID:7705339

Indiveri, C; Tonazzi, A; Giangregorio, N; Palmieri, F

1995-03-01

22

Sulfhydryl reagents and energy-linked reactions in monocot thylakoids.  

PubMed

Monofunctional maleimides have been used to covalently modify the coupling factor protein of monocot thylakoid membranes. As with dicot thylakoids, incubation of the monocot thylakoids with maleimides in the light but not in the dark results in inhibition of both ATP synthesis and hydrolysis. In the dark, sites on the gamma and epsilon subunits of maize Zea mays coupling factor 1 are modified after incubation of maize mesophyll thylakoids with the fluorescent maleimide N-(anilinonaphthyl-4) maleimide. A light accessible site localized solely to the gamma subunit has also been demonstrated. In contrast to the case with dicot thylakoids (spinach [Spinacia oleracea] and pea [Pisum sativum]) treatment of monocot thylakoids (maize, barley [Hordeum vulgare], crabgrass [Digitaria sanguinalis]) with bifunctional maleimides or thiol oxidants in the light does not result in functional uncoupling, i.e the bifunctional reagents act more like energy transfer inhibitors. The lack of functional uncoupling could be due either to a failure of the reagents to cross-link key sulfhydryl residues in the gamma subunit or to the continued ability of the gamma subunit to gate proton movements through the chloroplast coupling factor complex even though its conformation has been altered by sulfhydryl reagents. PMID:16667548

Cohen, W S; Baxter, D R

1990-07-01

23

A new hybridocytochemical method based on mercurated nucleic acid probes and sulfhydryl-hapten ligands  

Microsoft Academic Search

The mechanisms underlying a new hybridocytochemical method, which is based on mercurated nucleic acid probes and their binding to sulfhydryl-hapten ligands, have been studied. Furthermore we developed a simple procedure for the preparation of mercurated probes at a microgram scale. Nucleic acids immobilized on Sephadex beads have been immunochemically detected after hybridization with mercurated probes and binding of the sulfhydryl-hapten

A. H. N. Hopman; J. Wiegant; P. Duijn

1986-01-01

24

The Dynamic Disulfide Relay of Quiescin Sulfhydryl Oxidase  

PubMed Central

Protein stability, assembly, localization, and regulation often depend on formation of disulfide cross-links between cysteine side chains. Enzymes known as sulfhydryl oxidases catalyze de novo disulfide formation and initiate intra- and intermolecular dithiol/disulfide relays to deliver the disulfides to substrate proteins1,2. Quiescin sulfhydryl oxidase (QSOX) is a unique, multi-domain disulfide catalyst that is localized primarily to the Golgi apparatus and secreted fluids3 and has attracted attention due to its over-production in tumors4,5. In addition to its physiological importance, QSOX is a mechanistically intriguing enzyme, encompassing functions typically carried out by a series of proteins in other disulfide formation pathways. How disulfides are relayed through the multiple redox-active sites of QSOX and whether there is a functional benefit to concatenating these sites on a single polypeptide are open questions. We determined the first crystal structure of an intact QSOX enzyme, derived from a trypanosome parasite. Notably, sequential sites in the disulfide relay were found more than 40 Å apart in this structure, too far for direct disulfide transfer. To resolve this puzzle, we trapped and crystallized an intermediate in the disulfide hand-off, which showed a 165° domain rotation relative to the original structure, bringing the two active sites within disulfide bonding distance. The comparable structure of a mammalian QSOX enzyme, also presented herein, reveals additional biochemical features that facilitate disulfide transfer in metazoan orthologs. Finally, we quantified the contribution of concatenation to QSOX activity, providing general lessons for the understanding of multi-domain enzymes and the design of novel catalytic relays. PMID:22801504

Alon, Assaf; Grossman, Iris; Gat, Yair; Kodali, Vamsi K.; DiMaio, Frank; Mehlman, Tevie; Haran, Gilad; Baker, David; Thorpe, Colin; Fass, Deborah

2012-01-01

25

A Critical Interpersonal Distance Switches between Two Coordination Modes in Kendo Matches  

PubMed Central

In many competitive sports, players need to quickly and continuously execute movements that co-adapt to various movements executed by their opponents and physical objects. In a martial art such as kendo, players must be able to skillfully change interpersonal distance in order to win. However, very little information about the task and expertise properties of the maneuvers affecting interpersonal distance is available. This study investigated behavioral dynamics underlying opponent tasks by analyzing changes in interpersonal distance made by expert players in kendo matches. Analysis of preferred interpersonal distances indicated that players tended to step toward and away from their opponents based on two distances. The most preferred distance enabled the players to execute both striking and defensive movements immediately. The relative phase analysis of the velocities at which players executed steps toward and away revealed that players developed anti-phase synchronizations at near distances to maintain safe distances from their opponents. Alternatively, players shifted to in-phase synchronization to approach their opponents from far distances. This abrupt phase-transition phenomenon constitutes a characteristic bifurcation dynamics that regularly and instantaneously occurs between in- and anti-phase synchronizations at a critical interpersonal distance. These dynamics are profoundly affected by the task constraints of kendo and the physical constraints of the players. Thus, the current study identifies the clear behavioral dynamics that emerge in a sport setting. PMID:23284799

Okumura, Motoki; Kijima, Akifumi; Kadota, Koji; Yokoyama, Keiko; Suzuki, Hiroo; Yamamoto, Yuji

2012-01-01

26

A critical interpersonal distance switches between two coordination modes in kendo matches.  

PubMed

In many competitive sports, players need to quickly and continuously execute movements that co-adapt to various movements executed by their opponents and physical objects. In a martial art such as kendo, players must be able to skillfully change interpersonal distance in order to win. However, very little information about the task and expertise properties of the maneuvers affecting interpersonal distance is available. This study investigated behavioral dynamics underlying opponent tasks by analyzing changes in interpersonal distance made by expert players in kendo matches. Analysis of preferred interpersonal distances indicated that players tended to step toward and away from their opponents based on two distances. The most preferred distance enabled the players to execute both striking and defensive movements immediately. The relative phase analysis of the velocities at which players executed steps toward and away revealed that players developed anti-phase synchronizations at near distances to maintain safe distances from their opponents. Alternatively, players shifted to in-phase synchronization to approach their opponents from far distances. This abrupt phase-transition phenomenon constitutes a characteristic bifurcation dynamics that regularly and instantaneously occurs between in- and anti-phase synchronizations at a critical interpersonal distance. These dynamics are profoundly affected by the task constraints of kendo and the physical constraints of the players. Thus, the current study identifies the clear behavioral dynamics that emerge in a sport setting. PMID:23284799

Okumura, Motoki; Kijima, Akifumi; Kadota, Koji; Yokoyama, Keiko; Suzuki, Hiroo; Yamamoto, Yuji

2012-01-01

27

Fluorescent modification and orientation of myosin sulfhydryl 2 in skeletal muscle fibers  

Microsoft Academic Search

The authors describe a protocol for the selective covalent labeling of the sulfhydryl 2 (SH2) on the myosin cross-bridge in glycerinated muscle fibers using the sulfhydryl-selective label 4-(N-((iodoacetoxy)ethyl)-N-methylamino)-7-nitrobenz-2-oxa-1,3-diazole (IANBD). The protocol promotes the specificity of IANBD by using the ability to protect sulfhydryl 1 (SH1) from modification by binding the cross-bridge to the actin filament and using cross-bridge-bound MgADP to

Katalin Ajtai; Thomas P. Burghardt

1989-01-01

28

A critical role for the right fronto-insular cortex in switching between central-executive and default-mode networks.  

PubMed

Cognitively demanding tasks that evoke activation in the brain's central-executive network (CEN) have been consistently shown to evoke decreased activation (deactivation) in the default-mode network (DMN). The neural mechanisms underlying this switch between activation and deactivation of large-scale brain networks remain completely unknown. Here, we use functional magnetic resonance imaging (fMRI) to investigate the mechanisms underlying switching of brain networks in three different experiments. We first examined this switching process in an auditory event segmentation task. We observed significant activation of the CEN and deactivation of the DMN, along with activation of a third network comprising the right fronto-insular cortex (rFIC) and anterior cingulate cortex (ACC), when participants perceived salient auditory event boundaries. Using chronometric techniques and Granger causality analysis, we show that the rFIC-ACC network, and the rFIC, in particular, plays a critical and causal role in switching between the CEN and the DMN. We replicated this causal connectivity pattern in two additional experiments: (i) a visual attention "oddball" task and (ii) a task-free resting state. These results indicate that the rFIC is likely to play a major role in switching between distinct brain networks across task paradigms and stimulus modalities. Our findings have important implications for a unified view of network mechanisms underlying both exogenous and endogenous cognitive control. PMID:18723676

Sridharan, Devarajan; Levitin, Daniel J; Menon, Vinod

2008-08-26

29

A critical role for the right fronto-insular cortex in switching between central-executive and default-mode networks  

PubMed Central

Cognitively demanding tasks that evoke activation in the brain's central-executive network (CEN) have been consistently shown to evoke decreased activation (deactivation) in the default-mode network (DMN). The neural mechanisms underlying this switch between activation and deactivation of large-scale brain networks remain completely unknown. Here, we use functional magnetic resonance imaging (fMRI) to investigate the mechanisms underlying switching of brain networks in three different experiments. We first examined this switching process in an auditory event segmentation task. We observed significant activation of the CEN and deactivation of the DMN, along with activation of a third network comprising the right fronto-insular cortex (rFIC) and anterior cingulate cortex (ACC), when participants perceived salient auditory event boundaries. Using chronometric techniques and Granger causality analysis, we show that the rFIC-ACC network, and the rFIC, in particular, plays a critical and causal role in switching between the CEN and the DMN. We replicated this causal connectivity pattern in two additional experiments: (i) a visual attention “oddball” task and (ii) a task-free resting state. These results indicate that the rFIC is likely to play a major role in switching between distinct brain networks across task paradigms and stimulus modalities. Our findings have important implications for a unified view of network mechanisms underlying both exogenous and endogenous cognitive control. PMID:18723676

Sridharan, Devarajan; Levitin, Daniel J.; Menon, Vinod

2008-01-01

30

The role of microorganisms in the production of volatile sulfhydryl compounds in cheddar cheese slurries  

E-print Network

Acidifica- tion Statistical Analysis Gas Chromatography Cheesemaking Volatile Sulfhydryl compound Production in the Absence of Active Lactic Cultures Production of Volatile sulfhydryl compounds in Slurries Prepared from Direct Acid Curd 14 17 20 20.... The enormous effort expended determining chemical compounds that con- tribute to its flavor is a reflection of its economic importance. Cheddar cheese is manufactured on a large scale in more countries than any other cheese variety (28). The flavor...

Ponce-Trevino, Raul

2012-06-07

31

INACTIVATION OF AN INVERTEBRATE ACETYLCHOLINESTERASE BY SULFHYDRYL REAGENTS: A RECONSIDERATION OF THE IMPLICATIONS FOR INSECTICIDE DESIGN  

PubMed Central

Previously we used site-directed mutagenesis, in vitro expression, and molecular modeling to investigate the inactivation of an invertebrate acetylcholinesterase, cholinesterase 2 from amphioxus, by the sulfhydryl reagents 5,5’-dithiobis(2-nitrobenzoic acid) (DTNB) and N-ethylmaleimide (NEM). We created the mutants C310A, C466A, C310A/C466A and C310A/F312I to assess the roles of the two cysteines and a proposal that the increased rate of inactivation previously found in an F312I mutant was due to increased access of sulfhydryl reagents to Cys310. Our results indicated that both of the cysteines could be involved in inactivation by sulfhydryl reagents, but that the cysteine near the acyl pocket was more accessible. We speculated that the inactivation of aphid AChEs by sulfhydryl reagents was due to the presence of a cysteine homologous to Cys310 and proposed that this residue could be a target for a specific insecticide. Here we reconsider this proposal. PMID:18384763

Rowland, M.; Tsigelny, I.; Wolfe, M.; Pezzementi, L.

2008-01-01

32

N-iodoacetyltyramine: Preparation and use in sup 125 I labeling by alkylation of sulfhydryl groups  

SciTech Connect

Preparation and use of N-iodoacetyltyramine in generation of {sup 125}I-labeled compounds is described. The kinetics of alkylation of N-acetylcysteine by N-iodoacetyltyramine (k2 = 3.0 M-1 s-1) and N-chloroacetyltyramine (k2 = 0.12 M-1 s-1) indicate that N-iodoacetyltyramine is more useful for labeling sulfhydryl-containing compounds to high specific activity with {sup 125}I. Conditions for preparation of carrier-free {sup 125}I-labeled N-iodoacetyl-3-monoiodotyramine in 50% yield based on starting iodide are described. The high degree of group specificity of N-iodoacetyl-3-monoiodotyramine reaction with sulfhydryl groups is demonstrated by the high reactivity toward sulfhydryl-containing bovine serum albumin and low reactivity toward N-ethylmaleimide-blocked bovine serum albumin and IgG. {sup 125}I-labeled N-iodoacetyl-3-monoiodotyramine was also used to prepare an {sup 125}I-labeled ACTH derivative that retains full biological activity, further demonstrating the selectivity toward reactions with sulfhydryl groups.

Lin, C.M.; Mihal, K.A.; Krueger, R.J. (Univ. of Nebraska, Lincoln (USA))

1989-06-01

33

CHARACTERIZATION OF SULFHYDRYL PROTEINS INVOLVED IN THE MAINTENANCE OF FLAGELLAR STRAIGHTNESS IN HAMSTER SPERMATOZOA  

EPA Science Inventory

Hamster caput epididymal spermatozoa exhibit a marked 90-180 degree bend when induced to acquire progressive motility in vitro (Cornwall et al, 1988). lagellar bending is prevented by oxidizing sperm sulfhydryl (SH) groups with diamide. n the present study, the authors examined t...

34

Switch of sensitivity dynamics revealed with DyGloSA toolbox for dynamical global sensitivity analysis as an early warning for system's critical transition.  

PubMed

Systems with bifurcations may experience abrupt irreversible and often unwanted shifts in their performance, called critical transitions. For many systems like climate, economy, ecosystems it is highly desirable to identify indicators serving as early warnings of such regime shifts. Several statistical measures were recently proposed as early warnings of critical transitions including increased variance, autocorrelation and skewness of experimental or model-generated data. The lack of automatized tool for model-based prediction of critical transitions led to designing DyGloSA - a MATLAB toolbox for dynamical global parameter sensitivity analysis (GPSA) of ordinary differential equations models. We suggest that the switch in dynamics of parameter sensitivities revealed by our toolbox is an early warning that a system is approaching a critical transition. We illustrate the efficiency of our toolbox by analyzing several models with bifurcations and predicting the time periods when systems can still avoid going to a critical transition by manipulating certain parameter values, which is not detectable with the existing SA techniques. DyGloSA is based on the SBToolbox2 and contains functions, which compute dynamically the global sensitivity indices of the system by applying four main GPSA methods: eFAST, Sobol's ANOVA, PRCC and WALS. It includes parallelized versions of the functions enabling significant reduction of the computational time (up to 12 times). DyGloSA is freely available as a set of MATLAB scripts at http://bio.uni.lu/systems_biology/software/dyglosa. It requires installation of MATLAB (versions R2008b or later) and the Systems Biology Toolbox2 available at www.sbtoolbox2.org. DyGloSA can be run on Windows and Linux systems, -32 and -64 bits. PMID:24367574

Baumuratova, Tatiana; Dobre, Simona; Bastogne, Thierry; Sauter, Thomas

2013-01-01

35

Switch of Sensitivity Dynamics Revealed with DyGloSA Toolbox for Dynamical Global Sensitivity Analysis as an Early Warning for System's Critical Transition  

PubMed Central

Systems with bifurcations may experience abrupt irreversible and often unwanted shifts in their performance, called critical transitions. For many systems like climate, economy, ecosystems it is highly desirable to identify indicators serving as early warnings of such regime shifts. Several statistical measures were recently proposed as early warnings of critical transitions including increased variance, autocorrelation and skewness of experimental or model-generated data. The lack of automatized tool for model-based prediction of critical transitions led to designing DyGloSA – a MATLAB toolbox for dynamical global parameter sensitivity analysis (GPSA) of ordinary differential equations models. We suggest that the switch in dynamics of parameter sensitivities revealed by our toolbox is an early warning that a system is approaching a critical transition. We illustrate the efficiency of our toolbox by analyzing several models with bifurcations and predicting the time periods when systems can still avoid going to a critical transition by manipulating certain parameter values, which is not detectable with the existing SA techniques. DyGloSA is based on the SBToolbox2 and contains functions, which compute dynamically the global sensitivity indices of the system by applying four main GPSA methods: eFAST, Sobol's ANOVA, PRCC and WALS. It includes parallelized versions of the functions enabling significant reduction of the computational time (up to 12 times). DyGloSA is freely available as a set of MATLAB scripts at http://bio.uni.lu/systems_biology/software/dyglosa. It requires installation of MATLAB (versions R2008b or later) and the Systems Biology Toolbox2 available at www.sbtoolbox2.org. DyGloSA can be run on Windows and Linux systems, -32 and -64 bits. PMID:24367574

Baumuratova, Tatiana; Dobre, Simona; Bastogne, Thierry; Sauter, Thomas

2013-01-01

36

Differential effects of sulfhydryl reagents on saxitoxin and tetrodotoxin block of voltage-dependent Na channels.  

PubMed Central

We have probed a cysteine residue that confers resistance to tetrodotoxin (TTX) block in heart Na channels, with membrane-impermeant, cysteine-specific, methanethiosulfonate (MTS) analogs. Covalent addition of a positively charged group to the cysteinyl sulfhydryl reduced pore conductance by 87%. The effect was selectively prevented by treatment with TTX, but not saxitoxin (STX). Addition of a negatively charged group selectively inhibited STX block without affecting TTX block. These results agree with models that place an exposed cysteinyl sulfhydryl in the TTX site adjacent to the mouth of the pore, but do not support the contention that STX and TTX are interchangeable. The surprising differences between the two toxins are consistent with the hypothesis that the toxin-receptor complex can assume different conformations when STX or TTX bound. Images FIGURE 6 PMID:7696471

Kirsch, G E; Alam, M; Hartmann, H A

1994-01-01

37

Endogenous biochemical factors affecting the efficiency of some radioprotective or radiosensitizing drugs: sulfhydryl groups and lipid peroxides.  

PubMed

The changes in the amounts of blood and tissular sulfhydryl groups and lipid peroxides were investigated in lethally gamma-irradiated rats treated with cystamine, AET (radioprotectors) or alpha-methyl-dopa (a radiosensitizer). The results of experiments revealed the following findings: 1. The ionizing radiation generally causes increases in the levels of tissular sulfhydryl groups and lipid peroxides (excepting the hepatic levels of these compounds). 2. AET and, especially, cystamine are able to reverse the radiation-induced changes in the tissular amounts of sulfhydryl groups and lipid peroxides; there are close relationships between this effect (including its intensity and extension) and the radioprotective action of these drugs. 3. In spite of its radiosensitizing action, alpha-methyl-dopa induces approximately similar changes in the tissular amounts of sulfhydryl groups and lipid peroxides, suggesting that biochemical processes other than an excessive yield of free radicals are also involved in radiosensitivity. PMID:1258080

P?u?escu, E; P?un, C; Olinescu, R; Teodosiu, T

1976-01-01

38

EFFECTS OF THIMEROSAL, AN ORGANIC SULFHYDRYL MODIFYING AGENT, ON SEROTONIN TRANSPORT ACTIVITY INTO RABBIT BLOOD PLATELETS  

Microsoft Academic Search

The effects of the sulfhydryl group inhibitor thimerosal on serotonin (5-HT) transport activity into rabbit blood platelets were investigated, along with its effects on the intracellular concentration of Ca2+ ([Ca2+]i). 3H-5-HT transport activity into rabbit blood platelets was inhibited by treatment with 10?5 M thimerosal for 30 min, which did not cause 5-HT release from platelets. The thimerosal-induced inhibition of

HIROAKI NISHIO; KEN-ICHI NEZASA; JUN HIRANO; YOSHIHIRO NAKATA

1996-01-01

39

Probing the major skeletal muscle chloride channel with Zn 2+ and other sulfhydryl-reactive compounds  

Microsoft Academic Search

The sensitivity of the human skeletal muscle Cl–channel, hClC-1, towards various sulfhydryl-reactive agents was tested with the channel expressed in Xenopus oocytes and in human embryonic kidney cells. External but not internal Zn2+, at 1 mM, substantially reduced the current without affecting activation parameters. External Cd2+ and Hg2+ as well as organic mercurial compounds reduced the Cl–currents to a similar

L. Kürz; Susanne Wagner; Alfred L. George Jr.; Reinhardt Rüdel

1996-01-01

40

Sulfhydryl alkylating agents induce calcium current in skeletal muscle fibers of a crustacean ( Atya lanipes )  

Microsoft Academic Search

Summary Voltage-clamp experiments using the three-microelectrode voltage clamp technique were performed on ventroabdominal flexor muscles of the crustacean Atya lanipes. Potassium and chloride currents were found to underlie the normal, passive response of the muscle. Blocking potassium currents with tetraethylammonium and replacing chloride ions with methanesulfonate did not unmask an inward current. By treating the muscle with the sulfhydryl-alkylating agent

L. Lizardi; M. C. Garcia; J. A. Sanchez; C. Zuazaga

1992-01-01

41

Purification, characterization, and toxicity of the sulfhydryl-activated hemolysin listeriolysin O from Listeria monocytogenes.  

PubMed Central

We purified and characterized an extracellular hemolysin produced by Listeria monocytogenes. Hemolysin production was greatly enhanced by growing bacteria in resin (Chelex)-treated medium. This hemolysin was separated as a homogeneous protein of 60,000 daltons by using thiol-disulfide exchange affinity chromatography. This protein was a sulfhydryl-activated toxin, termed listeriolysin O, which shared the classical properties of other bacterial sulfhydryl-activated toxins: inhibition by very low amounts of cholesterol; activation by reducing agents and suppression of the lytic activity by oxidation; antigenic cross-reactivity with streptolysin O. However, listeriolysin O differed remarkably from the other sulfhydryl-activated toxins in that its cytolytic activity towards erythrocytes from various animal species was maximum at low pH (approximately 5.5) and was undetectable at pH 7.0. This suggests that the lytic activity of the toxin in host tissues might be better expressed in the acidic microenvironment, including macrophage phagosomes where bacteria presumably replicate. Listeriolysin O was lethal to mice (50% lethal dose of ca. 0.8 microgram) and induced a rapid inflammatory reaction when injected intradermally. These results favor the view that listeriolysin O might play a major role during intracellular replication of L. monocytogenes, ultimately promoting death of infected macrophages. Images PMID:3110067

Geoffroy, C; Gaillard, J L; Alouf, J E; Berche, P

1987-01-01

42

In vivo sulfhydryl distribution in brown cells of Mercenaria mercenaria exposed to cadmium  

SciTech Connect

Brown cells are found in the red glands of Mercenaria mercenaria (Bivalvia) and have a role in detoxification. Brown cell involvement in metal detoxification is due in part to endogenous glutathione (GSH) and protein bound sulfhydryl (PBSH). During treatment of Mercenaria with 0.5 and 1.0 ppm Cd{sup 2+}, brown cells were analyzed for total sulfhydryl (TSH), PBSH, non-protein bound sulfhydryl (NPSH) and GSH after 0.25, 1, 2, 3, 6, 12 and 20 days. Trend analyses indicated that treatment with 0.5 ppm Cd{sup 2+} caused a continuous increase in PBSH/TSH, whereas NPSH/TSH did not appear to change during 20 days treatment. The GSH/NPSH ratio increased significantly (P<0.01) for 6 days, followed by a significant (P<0.01) continuous decrease to day 20. Treatment with 1.0 ppm Cd{sup 2+} caused an increase in NPSH/TSH during the first 3 days, after which the ratio remained fairly constant to day 20, whereas PBSH/TSH decreased today 2, increased to day 3 and remained unchanged to day 20. The GSH/NPSH ratio remained fairly constant for the first 12 days after which it increased significantly (P<0.01). Histopathological examination after treatment with 1.0 ppm Cd 2{sup +} indicated darkening of the lysosomes during the first 2 days, followed by extensive brown cell sloughing into the tubule lumen and the abundance of small lysosomes at day 3. Sloughing and small lysosome formation continued to a lesser extent to day 20 when granulocyte infiltration and necrosis of the intertubular connective tissue occurred. The data indicate that GSH is more resistant to fluctuations than PBSH which suggests a more rapid synthesis or turnover rate for GSH. The ratio of GSH to PBSH has potential for a biomarker of cadmium exposure and health of Mercenaria.

Zaroogian, G. [Environmental Protection Agency, Narragansett, RI (United States)

1995-12-31

43

Definition of an electrostatic relay switch critical for the cAMP-dependent activation of protein kinase A as revealed by the D170A mutant of RIalpha.  

PubMed

The Regulatory (R) subunit of Protein Kinase A (PKA) inhibits its kinase activity by shielding the Catalytic (C) subunit from physiological substrates. This inhibition is reversed in response to extra-cellular signals that increase cAMP levels in the cytoplasm. Upon cAMP binding to R, C is allosterically released from R, activating a spectrum of downstream signaling cascades. Crystallographic data indicated that a series of distinct conformational changes within CBD-A must occur to relay the cAMP signal from the cAMP binding site to the R:C interaction interface. One critical cAMP relay site within the CBD-A of R has been identified as Asp170 because the D170A mutation selectively reduces the negative cooperativity between the cAMP- and C-recognition sites (i.e. the KD for the R:C complex in the presence of cAMP is reduced by more than 12-fold), without significantly compromising the high affinity of R for both binding partners. Here, utilizing an integrated set of comparative NMR analyses we have elucidated how this critical electrostatic switch is able to control the interaction network which transmits the cAMP signal within CBD-A. The D170A-induced variations in backbone chemical shifts as well as in hydrogen-deuterium and hydrogen-hydrogen exchange profiles show that Asp170 not only plays a pivotal role in controlling the local conformation of the phosphate binding cassette (PBC), where cAMP docks, but also significantly affects the long-range cAMP-dependent interaction network that extends from the PBC to the three major sites of C-recognition. We also found that the D170A mutation promotes partial unfolding, thus assisting the uncoupling of the alpha- and beta-subdomains of CBD-A as required for the major alpha-helical conformational re-arrangement necessary for C-binding. Overall, the emerging map of allosteric networks features Asp170 as an essential component of an electrostatic switch mechanism that stabilizes the conformation of the PBC region for optimal interaction with cAMP and that is also crucial for relaying allosteric effects leading to C subunit activation. Taken together, our results consolidate the interdependence between the Asp170 relay site and the R:C interaction interface. Furthermore, they provide insight into the driving forces for the in vivo formation of intermediate PKA ternary complexes. Finally, our current study is relevant for elucidating the antagonistic properties of Rp-cAMPS on PKA by providing a detailed picture of the long-range effects of the altered interaction between this analog and the PBC. PMID:17596845

Abu-Abed, Mona; Das, Rahul; Wang, Lijun; Melacini, Giuseppe

2007-10-01

44

Changes in sulfhydryl groups of honeybee glyceraldehyde phosphate dehydrogenase associated with generation of the intermediate plateau in its saturation kinetics  

NASA Technical Reports Server (NTRS)

Honeybee and rabbit muscle GPDH were studied to obtain information at the chemical level regarding anomolous saturation kinetics of the honeybee enzyme. Results demonstrate that the enzyme's sulfhydryl groups are implicated in the process. Measured by DTNB titration, native honeybee GPDH has one less active SH than the native rabbit muscle enzyme and displays changes in overall sulfhydryl reactivity after preincubation with G-3-P or G-3-P plus NAD+. The total DTNB reactive sulfhydryls of rabbit muscle GPDH are not changed by preincubation with NAD+ or G-3-P; honeybee GPDH, under certain conductions of preincubation with these ligands, shows a decrease of two total DTNB reactive SH groups. This difference has been confirmed by an independent experiment in which the two enzymes were carboxymethylated with C-14 bromoacetic acid.

Gelb, W. G.; Brandts, J. F.; Nordin, J. H.

1973-01-01

45

A non-radioactive in situ hybridization method based on mercurated nucleic acid probes and sulfhydryl-hapten ligands.  

PubMed Central

Mercurated nucleic acid probes can be used for non-radioactive in situ hybridization. The principle of the method is based on the reaction of the mercurated pyrimidine residues of the in situ hybridized probe with the sulfhydryl group of a ligand which contains a hapten. Next, the hapten is immunocytochemically detected. Previous experiments showed that stable coupling of the sulfhydryl ligands could only be obtained when positively charged amino groups are present in the ligand. On basis of this finding, ligands were synthesized containing a sulfhydryl group, two lysyl residues and hapten groups such as trinitrophenyl, fluorescyl and biotinyl. The ligands, free or bound to mercurated nucleic acids, were immunochemically characterized in ELISAs. The method was shown to be specific and sensitive in the detection of target DNA in situ on microscopic preparations and in dot-blot hybridization reactions on nitrocellulose. Images PMID:3748817

Hopman, A H; Wiegant, J; Tesser, G I; Van Duijn, P

1986-01-01

46

Effect of sulfhydryl group modification on the neurotoxic action of a sea snake toxin.  

PubMed

Pelamis toxin alpha is a major neurotoxin isolated from the venom of Pelamis platurus (yellow-bellied sea snake). The effect of sulfhydryl group modification by NN'-1,4-phenylenedimaleimide on the neurotoxic action of Pelamis toxin alpha has been investigated. The cross-linked toxin having a molecular weight of 11 000 was formed without significant structural changes in the toxin. Lethality tests on the modified toxin indicated that it retained considerable toxicity, although its potency was weaker than that of the native toxin. Binding studies with the acetylcholine receptor isolated from the electroplax of Torpedo californica indicated that the modified toxin binds to the receptor but less effectively than the native toxin. These results suggest that the decreases in toxicity and binding to the receptor are due to a decrease in accessibility of cross-linked neurotoxin to the receptor. This leads us to the conclusion that the region of the neurotoxin containing the sulfhydryl group is not essential for its biological activity. Analysis of the structure and function relationships of the modified toxin suggests that the neurotoxin-acetylcholine receptor interaction requires the proper orientation of the neurotoxin molecule. PMID:6141261

Ishizaki, H; Allen, M; Tu, A T

1984-01-01

47

Sulfhydryl Reagents and Energy-Linked Reactions in Monocot Thylakoids 1  

PubMed Central

Monofunctional maleimides have been used to covalently modify the coupling factor protein of monocot thylakoid membranes. As with dicot thylakoids, incubation of the monocot thylakoids with maleimides in the light but not in the dark results in inhibition of both ATP synthesis and hydrolysis. In the dark, sites on the ? and ? subunits of maize Zea mays coupling factor 1 are modified after incubation of maize mesophyll thylakoids with the fluorescent maleimide N-(anilinonaphthyl-4) maleimide. A light accessible site localized solely to the ? subunit has also been demonstrated. In contrast to the case with dicot thylakoids (spinach [Spinacia oleracea] and pea [Pisum sativum]) treatment of monocot thylakoids (maize, barley [Hordeum vulgare], crabgrass [Digitaria sanguinalis]) with bifunctional maleimides or thiol oxidants in the light does not result in functional uncoupling, i.e the bifunctional reagents act more like energy transfer inhibitors. The lack of functional uncoupling could be due either to a failure of the reagents to cross-link key sulfhydryl residues in the ? subunit or to the continued ability of the ? subunit to gate proton movements through the chloroplast coupling factor complex even though its conformation has been altered by sulfhydryl reagents. Images Figure 3 Figure 4 Figure 5 Figure 6 PMID:16667548

Cohen, William S.; Baxter, Donald R.

1990-01-01

48

Task switching  

Microsoft Academic Search

Everyday life requires frequent shifts between cognitive tasks. Research reviewed in this article probes the control processes that reconfigure mental resources for a change of task by requiring subjects to switch frequently among a small set of simple tasks. Subjects' responses are substantially slower and, usually, more error-prone immediately after a task switch. This ‘switch cost’ is reduced, but not

Stephen Monsell

2003-01-01

49

Exciter switch  

NASA Technical Reports Server (NTRS)

A new exciter switch assembly has been installed at the three DSN 64-m deep space stations. This assembly provides for switching Block III and Block IV exciters to either the high-power or 20-kW transmitters in either dual-carrier or single-carrier mode. In the dual-carrier mode, it provides for balancing the two drive signals from a single control panel located in the transmitter local control and remote control consoles. In addition to the improved switching capabilities, extensive monitoring of both the exciter switch assembly and Transmitter Subsystem is provided by the exciter switch monitor and display assemblies.

Mcpeak, W. L.

1975-01-01

50

Ellman's Test: Quantitative Determination of Peptides by Sulfhydryl (SH) Groups. Contributed by David Van Horn, Dept. of Chemistry, UC Berkeley  

E-print Network

Ellman's Test: Quantitative Determination of Peptides by Sulfhydryl (­SH) Groups. Contributed Overview This is the standard "Ellman's Test" for the determination of free thiols. (Ref. 1) It works well for small peptides and proteins synthesized using standard solid phase synthetic methods. Peptides from

Winfree, Erik

51

Nucleotide-Protectable Labeling of Sulfhydryl Groups in Subunit I of the ATPhase from Halobacterium Saccharovorum  

NASA Technical Reports Server (NTRS)

A membrane-bound ATPase from the archaebacterium Halobacterium saccharovorum is inhibited by N-ethyl-maleimide in a nucleotide-protectable manner. When the enzyme was incubated with N-[C-14]jethylmaleimide, the bulk of radioactivity was as- sociated with the 87,000-Da subunit (subunit 1). ATP, ADP, or AMP reduced incorporation of the inhibitor. No charge shift of subunit I was detected following labeling with N-ethylmaleimide, indicating an electroneutral reaction. The results are consistent with the selective modification of sulfhydryl groups in subunit I at or near the catalytic site and are further evidence of a resemblance between this archaebacterial ATPase and the vacuolar-type ATPases.

Sulzner, Michael; Stan-Lotter, Helga; Hochstein, Lawrence I.

1992-01-01

52

Role of Sulfhydryl Sites on Bacterial Cell Walls in the Biosorption, Mobility and Bioavailability of Mercury and Uranium  

SciTech Connect

The goal of this exploratory study is to provide a quantitative and mechanistic understanding of the impact of bacterial sulfhydryl groups on the bacterial uptake, speciation, methylation and bioavailability of Hg and redox changes of uranium. The relative concentration and reactivity of different functional groups present on bacterial surfaces will be determined, enabling quantitative predictions of the role of biosorption of Hg under the physicochemical conditions found at contaminated DOE sites.The hypotheses we propose to test in this investigation are as follows- 1) Sulfhydryl groups on bacterial cell surfaces modify Hg speciation and solubility, and play an important role, specifically in the sub-micromolar concentration ranges of metals in the natural and contaminated systems. 2) Sulfhydryl binding of Hg on bacterial surfaces significantly influences Hg transport into the cell and the methylation rates by the bacteria. 3) Sulfhydryls on cell membranes can interact with hexavalent uranium and convert to insoluble tetravalent species. 4) Bacterial sulfhydryl surface groups are inducible by the presence of metals during cell growth. Our studies focused on the first hypothesis, and we examined the nature of sulfhydryl sites on three representative bacterial species: Bacillus subtilis, a common gram-positive aerobic soil species; Shewanella oneidensis, a facultative gram-negative surface water species; and Geobacter sulfurreducens, an anaerobic iron-reducing gram-negative species that is capable of Hg methylation; and at a range of Hg concentration (and Hg:bacterial concentration ratio) in which these sites become important. A summary of our findings is as follows- ? Hg adsorbs more extensively to bacteria than other metals. Hg adsorption also varies strongly with pH and chloride concentration, with maximum adsorption occurring under circumneutral pH conditions for both Cl-bearing and Cl-free systems. Under these conditions, all bacterial species tested exhibit almost complete removal of Hg from the experimental solutions at relatively low bacterial concentrations. ? Synchrotron based X-ray spectroscopic studies of these samples indicate that the structure and the coordination environment of Hg surface complexes on bacterial cell walls change dramatically- with sulfhydryls as the dominant Hg-binding groups in the micromolar and submicromolar range, and carboxyls and phosphoryls dominating at high micromolar concentrations. ? Hg interactions change from a trigonal or T-shaped HgS{sub 3} complex to HgS or HgS{sub 2} type complexes as the Hg concentration increases in the submicromolar range. Although all bacterial species studied exhibited the same types of coordination environments for Hg, the relative concentrations of the complexes change as a function of Hg concentration.

Myneni, Satish C.; Mishra, Bhoopesh; Fein, Jeremy

2009-04-01

53

Sulfhydryl oxidation reduces hippocampal susceptibility to hypoxia-induced spreading depression by activating BK channels.  

PubMed

The cytosolic redox status modulates ion channels and receptors by oxidizing/reducing their sulfhydryl (SH) groups. We therefore analyzed to what degree SH modulation affects hippocampal susceptibility to hypoxia. In rat hippocampal slices, severe hypoxia caused a massive depolarization of CA1 neurons and a negative shift of the extracellular DC potential, the characteristic sign of hypoxia-induced spreading depression (HSD). Oxidizing SH groups by 5,5'-dithiobis 2-nitrobenzoic acid (DTNB, 2 mM) postponed HSD by 30%, whereas their reduction by 1,4-dithio-dl-threitol (DTT, 2 mM) or alkylation by N-ethylmaleimide (500 microM) hastened HSD onset. The DTNB-induced postponement of HSD was not affected by tolbutamide (200 microM), dl-2-amino-5-phosphonovaleric acid (150 microM), or 6-cyano-7-nitroquinoxaline-2,3-dione (25 microM). It was abolished, however, by Ni2+ (2 mM), withdrawal of extracellular Ca2+, charybdotoxin (25 nM), and iberiotoxin (50 nM). In CA1 neurons DTNB induced a moderate hyperpolarization, blocked spontaneous spike discharges and postponed the massive hypoxic depolarization. DTT induced burst firing, depolarized glial cells, and hastened the onset of the massive hypoxic depolarization. Schaffer-collateral/CA1 synapses were blocked by DTT but not by DTNB; axonal conduction remained intact. Mitochondria did not markedly respond to DTNB or DTT. While the targets of DTT are less clear, the postponement of HSD by DTNB indicates that sulfhydryl oxidation increases the tolerance of hippocampal tissue slices against hypoxia. We identified as the underlying mechanism the activation of BK channels in a Ca(2+)-sensitive manner. Accordingly, ionic disregulation and the loss of membrane potential occur later or might even be prevented during short-term insults. Therefore well-directed oxidation of SH groups could mediate neuroprotection. PMID:15872065

Hepp, Sebastian; Gerich, Florian J; Müller, Michael

2005-08-01

54

Arylation of sulfhydryl groups in vitro by the naturally occurring sesquiterpenoid benzoquinone avarone.  

PubMed

Avarone (AQ) is a naturally occurring sesquiterpenoid benzoquinone possessing antileukaemic activity. Its reactivity towards glutathione (GSH) and protein sulfhydryl (SH) groups was investigated. The stoichiometry of AQ reaction with GSH at [GSH]/[AQ] ratios lower than unity proved to be 1:2 (thiol:quinone), consistent with the formation of the corresponding hydroquinone (avarol) as well as a quinone-thioether in the reaction. Conversely, when the [GSH]/[AG] ratio was higher than unity, a hydroquinone-thioether was the only reaction product. AQ/protein interaction was also investigated by using bovine serum albumin (BSA) as model compound. As observed with GSH, arylation rather than oxidation of SH groups appeared to be the mechanism responsible for the AQ-induced depletion of protein SH groups. However, AQ proved to be less effective in depleting BSA sulfhydryls than that of GSH. AQ disappearance after BSA addition was greater than expected on the basis of the total SH groups depleted, if a stoichiometric ratio 1:2 (thiol:quinone) was assumed. It also occurred in the presence of BSA with blocked SH groups, thus suggesting that AQ may react with other nucleophilic protein residues, such as amino or imino groups. When HepG2 cells were exposed to AQ, depletion of both protein SH groups and GSH occurred. However, in contrast to the above, AQ proved to be more effective, probably because of its lipophilic nature, in depleting protein SH groups than GSH. Also, in intact cells AQ appeared to arylate both SH and other nucleophilic groups in proteins. This mechanism may play a major role in AQ-induced cytotoxicity. PMID:8134925

Belisario, M A; Pecce, R; Maturo, M; De Rosa, S

1994-01-26

55

Flavin-linked Erv-family sulfhydryl oxidases release superoxide anion during catalytic turnover.  

PubMed

Typically, simple flavoprotein oxidases couple the oxidation of their substrates with the formation of hydrogen peroxide without release of significant levels of the superoxide ion. However, two evolutionarily related single-domain sulfhydryl oxidases (Erv2p; a yeast endoplasmic reticulum resident protein and augmenter of liver regeneration, ALR, an enzyme predominantly found in the mitochondrial intermembrane) release up to ~30% of the oxygen they reduce as the superoxide ion. Both enzymes oxidize dithiol substrates via a redox-active disulfide adjacent to the flavin cofactor within the helix-rich Erv domain. Subsequent reduction of the flavin is followed by transfer of reducing equivalents to molecular oxygen. Superoxide release was initially detected using tris(3-hydroxypropyl)phosphine (THP) as an alternative reducing substrate to dithiothreitol (DTT). THP, and other phosphines, showed anomalously high turnover numbers with Erv2p and ALR in the oxygen electrode, but oxygen consumption was drastically suppressed upon the addition of superoxide dismutase. The superoxide ion initiates a radical chain reaction promoting the aerobic oxidation of phosphines with the formation of hydrogen peroxide. Use of a known flux of superoxide generated by the xanthine/xanthine oxidase system showed that one superoxide ion stimulates the reduction of 27 and 4.5 molecules of oxygen using THP and tris(2-carboxyethyl)phosphine (TCEP), respectively. This superoxide-dependent amplification of oxygen consumption by phosphines provides a new kinetic method for the detection of superoxide. Superoxide release was also observed by a standard chemiluminescence method using a luciferin analogue (MCLA) when 2 mM DTT was employed as a substrate of Erv2p and ALR. The percentage of superoxide released from Erv2p increased to ~65% when monomeric mutants of the normally homodimeric enzyme were used. In contrast, monomeric multidomain quiescin sulfhydryl oxidase enzymes that also contain an Erv FAD-binding fold release only 1-5% of their total reduced oxygen species as the superoxide ion. Aspects of the mechanism and possible physiological significance of superoxide release from these Erv-domain flavoproteins are discussed. PMID:22148553

Daithankar, Vidyadhar N; Wang, Wenzhong; Trujillo, Joliene R; Thorpe, Colin

2012-01-10

56

Acceleration switch  

DOEpatents

The disclosure relates to an improved integrating acceleration switch of the type having a mass suspended within a fluid filled chamber, with the motion of the mass initially opposed by a spring and subsequently not so opposed.

Abbin, Jr., Joseph P. (Albuquerque, NM); Devaney, Howard F. (Cedar Crest, NM); Hake, Lewis W. (Albuquerque, NM)

1982-08-17

57

Magnetic switching  

SciTech Connect

Magnetic switching is a pulse compression technique that uses a saturable inductor (reactor) to pass pulses of energy between two capacitors. A high degree of pulse compression can be achieved in a network when several of these simple, magnetically switched circuits are connected in series. Individual inductors are designed to saturate in cascade as a pulse moves along the network. The technique is particularly useful when a single-pulse network must be very reliable or when a multi-pulse network must operate at a high pulse repetition frequency (PRF). Today, magnetic switches trigger spark gaps, sharpen the risetimes of high energy pulses, power large lasers, and drive high PRF linear induction accelerators. This paper will describe the technique of magnetic pulse compression using simple networks and design equations. A brief review of modern magnetic materials and of their role in magnetic switch design will be presented. 12 refs., 8 figs.

Kirbie, H.C.

1989-04-14

58

An Optical Crosspoint Buffered Switching Architecture Lin Cai,1, 2  

E-print Network

& Networks, Pecking University, China Abstract - We propose an optical crosspoint buffered switching fabric to simplify the implementation of optical packet switches. With the proposed switching fabric architecture of the critical components of optical packet switching. Current optical buffers are mainly based on fiber delay

Wai, Ping-kong Alexander

59

Momentum switches  

E-print Network

Certain continuous-time quantum walks can be viewed as scattering processes. These processes can perform quantum computations, but it is challenging to design graphs with desired scattering behavior. In this paper, we study and construct momentum switches, graphs that route particles depending on their momenta. We also give an example where there is no exact momentum switch, although we construct an arbitrarily good approximation.

Andrew M. Childs; David Gosset; Daniel Nagaj; Mouktik Raha; Zak Webb

2014-06-17

60

Influence of certain essential oils on carcinogen?metabolizing enzymes and acid?soluble sulfhydryls in mouse liver  

Microsoft Academic Search

The influence of essential oils from naturally occurring plant dietary items such as cardamom, celery seed, cumin seed, coriander, ginger, nutmeg, and zanthoxylum on the activities of hepatic carcinogen?metabolizing enzymes (cytochrome P450, aryl hydrocarbon hydroxylase, and glu?tathione S?transferase) and acid?soluble sulfhydryl level was investigated in Swiss albino mice. Each oil was fed by gavage at 10 ?l\\/day for 14 days,

Sanjeev Banerjee; Roopa Sharma; Raosaheb K. Kale; A. Ramesha Rao

1994-01-01

61

Non-sulfhydryl-containing angiotensin-converting enzyme inhibitor (MK421): evidence for role of renin system in normotensive subjects  

Microsoft Academic Search

A non-sulfhydryl-containing inhibitor of angiotensin-converting enzyme (MK421) was given as a single dose in a randomised double-blind cross-over trial using 20 mg and 5 mg of MK-421 or matched placebo to nine normotensive volunteers receiving a sodium intake of 150 mmol (mEq) daily. The two dosages of MK-421 caused similar, significant falls in supine and standing blood pressure, which were

G A MacGregor; N D Markandu; J Bayliss; J E Roulston; M Squires; J J Morton

1981-01-01

62

False-positive results for ketone with the drug mesna and other free-sulfhydryl compounds.  

PubMed

All free-sulfhydryl compounds tested produced false-positive reactions in the Legal test for ketones. The color developed in the ketone pad of urine dipsticks [N-Multistix SG, Multistix 10 SG (Ames), and Chemstrip 9 (Boehringer-Mannheim)] was misinterpreted for ketone bodies, both by visual and automated reading. In contrast to the reaction with true ketones, a drop of glacial acetic acid added onto the ketone pad of dipsticks discharged the false-positive red color. A red-violet also developed instantly with free -SH compounds in the Acetest tablet assay (Ames), but quickly faded. In general, the presence of acidic groups such as -COOH and -SO3H in the structure appeared to increase the nitroprusside reactivity of free -SH compounds, whereas the presence of a -NH2 group appeared to decrease it. Currently, false-positive ketone reactions ascribable to a free -SH group are most likely to be seen for urine containing mesna. The false-positive test for ketones caused by free -SH compounds can be recognized and ruled out by proper procedures. On the other hand, this chromogenic reaction with free thiols might be used for monitoring urinary excretion of mesna. PMID:3100102

Csako, G

1987-02-01

63

Protein Substrate Discrimination in the Quiescin-sulfhydryl Oxidase (QSOX) Family†  

PubMed Central

This work explores the substrate specificity of the Quiescin-sulfhydryl oxidase (QSOX) family of disulfide-generating flavoenzymes to provide enzymological context for investigation of the physiological roles of these facile catalysts of oxidative protein folding. QSOX enzymes are generally unable to form disulfide bonds within well-structured proteins. Use of a temperature-sensitive mutant of ubiquitin-conjugating enzyme 4 (Ubc4?) as a model substrate shows that QSOX activity correlates with the unfolding of Ubc4? monitored by circular dichroism. Fusion of Ubc4? with the more stable glutathione-S-transferase domain demonstrates that QSOX can selectively introduce disulfides into the less stable domain of the fusion protein. In terms of intermolecular disulfide bond generation, QSOX is unable to crosslink well-folded globular proteins via their surface thiols. However, the construction of a septuple mutant of RNase A, retaining a single cysteine residue, demonstrates that flexible protein monomers can be directly coupled by the oxidase. Steady- and pre-steady state kinetic experiments, combined with static fluorescence approaches, indicate that while QSOX is an efficient catalyst for disulfide bond formation between mobile elements of structure, it does not appear to have a significant binding site for unfolded proteins. These aspects of protein substrate discrimination by QSOX family members are rationalized in terms of the stringent steric requirements for disulfide exchange reactions. PMID:22582951

Codding, Jennifer A.; Israel, Benjamin A.; Thorpe, Colin

2012-01-01

64

Production and characterisation of AoSOX2 from Aspergillus oryzae , a novel flavin-dependent sulfhydryl oxidase with good pH and temperature stability  

Microsoft Academic Search

Sulfhydryl oxidases have found application in the improvement of both dairy and baking products due to their ability to oxidise\\u000a thiol groups in small molecules and cysteine residues in proteins. A genome mining study of the available fungal genomes had\\u000a previously been performed by our group in order to identify novel sulfhydryl oxidases suitable for industrial applications\\u000a and a representative

Greta Faccio; Kristiina Kruus; Johanna Buchert; Markku Saloheimo

2011-01-01

65

Phenylethynyl-butyltellurium inhibits the sulfhydryl enzyme Na+, K+ -ATPase: an effect dependent on the tellurium atom.  

PubMed

Organotellurium compounds are known for their toxicological effects. These effects may be associated with the chemical structure of these compounds and the oxidation state of the tellurium atom. In this context, 2-phenylethynyl-butyltellurium (PEBT) inhibits the activity of the sulfhydryl enzyme, ?-aminolevulinate dehydratase. The present study investigated on the importance of the tellurium atom in the PEBT ability to oxidize mono- and dithiols of low molecular weight and sulfhydryl enzymes in vitro. PEBT, at high micromolar concentrations, oxidized dithiothreitol (DTT) and inhibited cerebral Na(+), K(+)-ATPase activity, but did not alter the lactate dehydrogenase activity. The inhibition of cerebral Na(+), K(+)-ATPase activity was completely restored by DTT. By contrast, 2-phenylethynyl-butyl, a molecule without the tellurium atom, neither oxidized DTT nor altered the Na(+), K(+)-ATPase activity. In conclusion, the tellurium atom of PEBT is crucial for the catalytic oxidation of sulfhydryl groups from thiols of low molecular weight and from Na(+), K(+)-ATPase. PMID:23955422

Quines, Caroline B; Rosa, Suzan G; Neto, José S S; Zeni, Gilson; Nogueira, Cristina W

2013-11-01

66

Facile Preparation of Biocompatible Sulfhydryl Cotton Fiber-Based Sorbents by "Thiol-ene" Click Chemistry for Biological Analysis.  

PubMed

Sulfhydryl cotton fiber (SCF) has been widely used as adsorbent for a variety of metal ions since 1971. Thanks to the abundant thiols on SCF, in this study, we reported a universal method for the facile preparation of SCF-based materials using "thiol-ene" click chemistry for the first time. With the proposed method, two types of SCF-based materials, phenylboronic acid grafted sulfhydryl cotton fiber (SCF-PBA) and zirconium phosphonate-modified sulfhydryl cotton fiber (SCF-pVPA-Zr(4+)), were successfully prepared. The grafted functional groups onto the thiol group of SCF were demonstrated by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX). The prepared fibrous materials exhibited excellent fiber strength, good stability in aqueous or nonaqueous solutions, and great biocompatibility. Moreover, we developed filter-free in-pipet-tip SPE using these SCF-based materials as adsorbent for the enrichment of ribonucleosides, glycopeptides and phosphopeptides. Our results showed that SCF-PBA adsorbent can selectively capture ribonucleosides and glycopeptides from complex biological samples. And SCF-pVPA-Zr(4+) adsorbent exhibited high selectivity and capacity in the enrichment of phosphopeptides from the digestion mixture of ?-casein and bovine serum albumin (BSA), as well as human serum and nonfat milk digest. Generally, the preparation strategy can be a universal method for the synthesis of other functionalized cotton-based adsorbents with special requirement in microscale biological analysis. PMID:25268138

He, Xiao-Mei; Zhu, Gang-Tian; Zhu, Yuan-Yuan; Chen, Xi; Zhang, Zheng; Wang, Shao-Ting; Yuan, Bi-Feng; Feng, Yu-Qi

2014-10-22

67

Optical Networks Circuit switched, Burst switched,  

E-print Network

Optical Networks Circuit switched, Burst switched, Packet switched Electronic vs. Optical) ·switched networks ? (Gigabit Ethernet) · optical core (WAN) · routed virtual topology (circuits/leased lines) ( )·dynamic provisioning (circuits ondemand) ·optical burst (packet/flow) switching (IP) Packet

Shihada, Basem

68

Optical switch  

DOEpatents

An optical switching device (10) is provided whereby light from a first glass fiber (16) or a second glass fiber (14) may be selectively transmitted into a third glass fiber (18). Each glass fiber is provided with a focusing and collimating lens system (26, 28, 30). In one mode of operation, light from the first glass fiber (16) is reflected by a planar mirror (36) into the third glass fiber (18). In another mode of operation, light from the second glass fiber (14) passes directly into the third glass fiber (18). The planar mirror (36) is attached to a rotatable table (32) which is rotated to provide the optical switching.

Reedy, Robert P. (Livermore, CA)

1987-01-01

69

Switched power workshop. [Switched power electron guns  

SciTech Connect

This paper discusses the design of a switched power electron gun. Particular topics discussed are: vacuum photodiode switch; laser switched solid state diodes; gun performance; charging supply; and laser requirements. (LSP)

Palmer, R.B.

1988-01-01

70

Modification Of A Communication Switch In A Helicopter  

NASA Technical Reports Server (NTRS)

Report describes preliminary study of modification of electronic circuitry connected to communication-channel-selecting switches in AH-1 Cobra helicopter. Switches in question are foot switch and cyclic thumb-wheel switch mounted on joystick flight control. Modification enables pilots and other crewmembers to select radio channels or intercommunication with less diversion of attention from flight control and other critical tasks. Intended to enhance safety and performance in critical situations.

Haworth, Loran; Szoboszlay, Zoltan; Shively, Robert; Bick, Frank J.

1992-01-01

71

Switching Transistor  

NASA Technical Reports Server (NTRS)

Westinghouse Electric Corporation's D60T transistors are used primarily as switching devices for controlling high power in electrical circuits. It enables reduction in the number and size of circuit components and promotes more efficient use of energy. Wide range of application from a popcorn popper to a radio frequency generator for solar cell production.

1981-01-01

72

Information Switching Processor (ISP) contention analysis and control  

NASA Technical Reports Server (NTRS)

In designing a satellite system with on-board processing, the selection of a switching architecture is often critical. The on-board switching function can be implemented by circuit switching or packet switching. Destination-directed packet switching has several attractive features, such as self-routing without on-board switch reconfiguration, no switch control memory requirement, efficient bandwidth utilization for packet switched traffic, and accommodation of circuit switched traffic. Destination-directed packet switching, however, has two potential concerns: (1) contention and (2) congestion. And this report specifically deals with the first problem. It includes a description and analysis of various self-routing switch structures, the nature of contention problems, and contention and resolution techniques.

Inukai, Thomas

1995-01-01

73

Redox Factor-1 Activates Endothelial SIRTUIN1 through Reduction of Conserved Cysteine Sulfhydryls in Its Deacetylase Domain  

PubMed Central

Apurinic/Apyrmidinic Endonuclease 1/Redox Factor-1 (APE1/Ref-1) is a reductant which is important for vascular homeostasis. SIRTUIN1 (SIRT1) is a lysine deacetylase that also promotes endothelium-dependent vasorelaxation. We asked if APE1/Ref-1 governs the redox state and activity of SIRT1, and whether SIRT1 mediates the effect of APE1/Ref-1 on endothelium-dependent vascular function. APE1/Ref-1 maintains sulfhydryl (thiol) groups of cysteine residues in SIRT1 in the reduced form and promotes endothelial SIRT1 activity. APE1/Ref-1 stimulates SIRT1 activity by targeting highly conserved vicinal thiols 371 and 374 which form a zinc tetra-thiolate motif in the deacetylase domain of SIRT1. Cysteine residues in the N-terminal redox domain of APE1/Ref-1 are essential for reducing SIRT1 and stimulating its activity. APE1/Ref-1 protects endothelial SIRT1 from hydrogen peroxide-induced oxidation of sulfhydryls and from inactivation. APE1/Ref-1 also promotes lysine deacetylation of the SIRT1 target endothelial nitric oxide synthase (eNOS). SIRT1 mutated at cysteines 371 and 374, which renders it non-reducible by APE1/Ref-1, prevents lysine deacetylation of eNOS by APE1/Ref-1. SIRT1 free thiol (reduced sulfhydryl) content and deacetylase activity are diminished in all examined tissues of APE1/Ref-1+/? mice, including the vasculature. Overexpression of SIRT1 in aortas of APE1/Ref-1+/? mice restores endothelium-dependent vasorelaxation and bioavailable nitric oxide (NO) to levels similar to those observed in wild-type mice. Thus, APE1/Ref-1, by maintaining functionally important cysteine sulfhydryls in SIRT1 in the reduced form, promotes endothelial SIRT1 activity. This reductive activation of endothelial SIRT1 by APE1/Ref-1 mediates the effect of APE1/Ref-1 on eNOS acetylation, promoting endothelium-derived NO and endothelium-dependent vasorelaxation. PMID:23755229

Naqvi, Asma; Yamamori, Tohru; Kumar, Santosh; Kumar, Ajay; Irani, Kaikobad

2013-01-01

74

Sulfhydryl-dependent attachment of Treponema denticola to laminin and other proteins.  

PubMed Central

Attachment of Treponema denticola ATCC 35405 to laminin, a major basement membrane protein, and to other proteins was studied. Microdilution plates were coated with the proteins, and the attachment of T. denticola was measured by the enzyme-linked immunosorbent assay technique. Compared with bovine serum albumin (BSA), T. denticola had a high affinity to laminin, fibronectin, fibrinogen, and gelatin, as well as to type I and type IV collagens. Attachment to RGD peptide (Gly-Arg-Gly-Asp-Ser, the integrin recognition sequence) was only about 30% of that to laminin and was comparable to attachment to BSA. Tests with laminin fragments obtained through elastase digestion showed that the spirochetes attached well to an A-chain 140-kDa fragment involved in eukaryote cell attachment but did not attach to a 50-kDa fragment that includes the heparin binding site. Pretreatment of T. denticola with soluble laminin, fibronectin, gelatin, BSA, or fibrinogen had no effect on the attachment of the bacteria to laminin or fibronectin. A wide variety of compounds were tested for their possible inhibitory actions on the attachment. While most treatments of T. denticola ATCC 35405 had little or no effect on the attachment to proteins, sulfhydryl reagents p-chloromercuribenzoic acid (pCMBA) and oxidized glutathione inhibited the attachment by 70 to 99%, depending on the protein. When T. denticola was first allowed to attach to proteins, addition of pCMBA or oxidized glutathione could no longer reverse the attachment. Heat treatment of the spirochetes also markedly reduced the attachment to laminin, gelatin, and fibrinogen but not to BSA. Mixed glycosidase treatment of the spirochetes inhibited the attachment by 20 to 80%. None of the above treatments of the substrate proteins had any marked effect on the spirochete attachment. The results indicate that T. denticola has the capacity to bind to many different kinds of proteins by utilizing specific attachment mechanisms. The binding appears to involve protein SH groups and/or carbohydrate residues on the surface of T. denticola. Images PMID:1937780

Haapasalo, M; Singh, U; McBride, B C; Uitto, V J

1991-01-01

75

Human augmenter of liver regeneration: probing the catalytic mechanism of a flavin-dependent sulfhydryl oxidase.  

PubMed

Augmenter of liver regeneration is a member of the ERV family of small flavin-dependent sulfhydryl oxidases that contain a redox-active CxxC disulfide bond in redox communication with the isoalloxazine ring of bound FAD. These enzymes catalyze the oxidation of thiol substrates with the reduction of molecular oxygen to hydrogen peroxide. This work studies the catalytic mechanism of the short, cytokine form of augmenter of liver regeneration (sfALR) using model thiol substrates of the enzyme. The redox potential of the proximal disulfide in sfALR was found to be approximately 57 mV more reducing than the flavin chromophore, in agreement with titration experiments. Rapid reaction studies show that dithiothreitol (DTT) generates a transient mixed disulfide intermediate with sfALR signaled by a weak charge-transfer interaction between the thiolate of C145 and the oxidized flavin. The subsequent transfer of reducing equivalents to the flavin ring is relatively slow, with a limiting apparent rate constant of 12.4 s(-1). However, reoxidation of the reduced flavin by molecular oxygen is even slower (2.3 s(-1) at air saturation) and thus largely limits turnover at 5 mM DTT. The nature of the charge-transfer complexes observed with DTT was explored using a range of simple monothiols to mimic the initial nucleophilic attack on the proximal disulfide. While ?-mercaptoethanol is a very poor substrate of sfALR (?0.3 min(-1) at 100 mM thiol), it rapidly generates a mixed disulfide intermediate allowing the thiolate of C145 to form a strong charge-transfer complex with the flavin. Unlike the other monothiols tested, glutathione is unable to form charge-transfer complexes and is an undetectable substrate of the oxidase. These data are rationalized on the basis of the stringent steric requirements for thiol-disulfide exchange reactions. The inability of the relatively bulky glutathione to attain the in-line geometry required for efficient disulfide exchange in sfALR may be physiologically important in preventing the oxidase from catalyzing the potentially harmful oxidation of intracellular glutathione. PMID:24147449

Schaefer-Ramadan, Stephanie; Gannon, Shawn A; Thorpe, Colin

2013-11-19

76

Reset Switching Probability of Resistive Switching Devices  

Microsoft Academic Search

The reset switching probability of resistive switching devices is characterized in array testing. The measured switching probability can be quantitatively explained based on the mecha- nism of a thermally activated reset process. An analytical model of switching probability is developed to describe the dependence of reset probability on operation parameters, including applied voltage, selection transistor gate voltage, and pulsewidth. The

An Chen; Ming-Ren Lin

2011-01-01

77

Integrated photonic switches for nanosecond packet-switched  

E-print Network

-speed waveguide switches for optical packet-switched routers and networks," OFC, paper MF53, Los Angeles, CAIntegrated photonic switches for nanosecond packet-switched optical wavelength conversion Onur controlled packet switching with a reconfiguration time of packet switching

Demir, Hilmi Volkan

78

Packet switching. [Contains glossary  

SciTech Connect

This report assembles information on the theories of store-and-forward packet switching, and surveys existing operational packet-switching networks. It includes a comparison of the types of packet switching; packet-switching techniques; procedures for controlling errors, flow, and congestion; and protocol layers used in packet-switching networks. 132 references, 25 figures, 2 tables.

Derr, K.W.

1980-03-01

79

Free-space micromachined optical switches with submillisecond switching time for large-scale optical crossconnects  

Microsoft Academic Search

Optical crossconnects with large port counts are fast becoming critical components for high-capacity optical transport networks. The free-space micromachined optical switches (FS-MOS) demonstrated in this letter represent a means of filling this network need by combining the advantages of free-space interconnection with the virtues of integrated optics. Featuring free-rotating hinged micromirrors, the switch overcomes the common drawback of mechanical-type switches,

L. Y. Lin; E. L. Goldstein; R. W. Tkach

1998-01-01

80

Is the normal content of sulfhydryl groups attributable to sparing from dystrophic pathology in dystrophin-deficient muscles?  

PubMed

Deficiency of dystrophin in skeletal muscles is supposed to be responsible for all the symptoms associated with Duchenne dystrophy (DMD) and Becker dystrophy (BMD). The dystrophin-deficient mdx mice, however, are clinically almost asymptomatic. Hence, other factor(s) might be responsible for the muscle pathology in DMD and BDM. As sulfhydryl groups are involved in maintaining the structure of membranes and the protein-phospholipid interactions, total, protein-bound and free sulfhydryl groups (-SH) in DMD, BMD, limb-girdle dystrophy (LGMD) and the mdx mice muscles have been determined. A significant decrease of total and protein-bound -SH groups content and an increased proportion of free -SH groups in DMD and BMD was found. In LGMD the changes of total and protein-bound -SH groups content were less expressed. In the mdx mice muscles the content of -SH groups was generally normal, only a higher than normal proportion of free-SH groups content in old and senile animals, especially in their diaphragm, was present. To test the sarcolemmal integrity, albumin/creatine kinase (CK) influx/efflux was determined. In early stages of DMD and BMD the albumin influx was increased. In advanced stages of these diseases albumin influx was not observed. In LGMD albumin penetration was present only in a few fibres. CK efflux in vitro was increased both in early and advanced DMD cases. In BMD and LGMD CK efflux was increased only in early stages of the diseases. In mdx mice an increased influx/efflux of albumin/CK was stated in adult animals. The changes persisted in the mdx hind limb muscles up to the senile age of the animals. In the mdx diaphragm of senile animals albumin did not penetrate the muscle cell and no increase of CK efflux was observed. It is suggested that changes in the distribution of -SH groups take part in the molecular disorganisation of the sarcolemma in course dystrophinopathies. Normal content of the sulfhydryl groups is supposed to be attributable to sparing from dystrophic pathology in dystrophin-deficient mdx mice muscles. PMID:12572920

Niebrój-Dobosz, Irena; Fidzia?ska, Anna; Glinka, Zofia; Hausmanowa-Petrusewicz, Irena

2002-01-01

81

Defining the Cancer Master Switch  

Microsoft Academic Search

Background  Recent research has focused on signaling cascades and their interactions yielding considerable insight into which genetic\\u000a pathways are targeted and how they tend to be altered in tumors. Therapeutic interventions now can be designed based on the\\u000a knowledge of pathways vital to tumor growth and survival. These critical targets for intervention, master switches for cancer,\\u000a are termed so because the

Courtney J. Balentine; David H. Berger; Shi-He Liu; Changyi Chen; John Nemunaitis; F. Charles Brunicardi

82

Temporal switching jitter in photoconductive switches  

SciTech Connect

This paper reports on a recent comparison made between the Air Force Research Laboratory (AFRL) gallium arsenide, optically-triggered switch test configuration and the Sandia National Laboratories (SNL) gallium arsenide, optically-triggered switch test configuration. The purpose of these measurements was to compare the temporal switch jitter times. It is found that the optical trigger laser characteristics are dominant in determining the PCSS jitter.

GAUDET,JOHN A.; SKIPPER,MICHAEL C.; ABDALLA,MICHAEL D.; AHERN,SEAN M.; MAR,ALAN; LOUBRIEL,GUILLERMO M.; ZUTAVERN,FRED J.; O'MALLEY,MARTIN W.; HELGESON,WESLEY D.; ROMERO,SAMUEL P.

2000-04-13

83

Irreversible activation of cyclic nucleotide-gated ion channels by sulfhydryl-reactive derivatives of cyclic GMP.  

PubMed

First discovered in the sensory epithelium of the visual and olfactory systems, cyclic nucleotide-gated (CNG) ion channels have now been found in tissues throughout the body. Native rod CNG channels are tetramers composed of homologous, but distinct, alpha- and beta-subunits. The goal of this study was to develop a novel method for targeting covalent attachment of cGMP to individual subunit types. Toward this goal, we have found that treatment of membrane patches expressing rod alpha-subunit channels with sulfhydryl-reactive derivatives of cGMP resulted in irreversible activation. The persistent currents were sensitive to block by both Mg(2+) and tetracaine. Pretreatment of the patch with the sulfhydryl-blocking reagents N-ethylmaleimide (NEM) and bis-dithionitrobenzoic acid (DTNB) prevented covalent activation; the effect of DTNB was reversed by reduction with DTT. Furthermore, the process of covalent activation was dramatically slowed by the presence of an excess of 8-Br-cGMP. These results suggested that covalent activation resulted from the tethering of cGMP near the channel's ligand-binding sites by reaction with an endogenous cysteine. The alpha-subunit of the rod channel contains seven cysteine residues, and we set out to determine the site of attachment by site-directed mutagenesis. Surprisingly, irreversible activation was not abolished by elimination of all seven cysteine residues. This result suggests that the site of attachment is on a tightly associated protein, rather than on the channel protein itself. To further investigate these results, we treated patches containing irreversibly activated channels with 100 microg/mL trypsin and discovered two modes of covalent activation. One type developed rapidly and was removed by trypsin treatment, and the second developed slowly and was resistant to trypsin treatment. Both types of covalent activation were present in all mutants tested and were also present when CNG channels were expressed in HEK-293 cells. These results suggest that CNG channel subunits may associate with endogenous proteins when they are expressed in heterologous systems. PMID:10631005

Brown, R L; Haley, T L; Snow, S D

2000-01-18

84

Latching micro optical switch  

DOEpatents

An optical switch reliably maintains its on or off state even when subjected to environments where the switch is bumped or otherwise moved. In addition, the optical switch maintains its on or off state indefinitely without requiring external power. External power is used only to transition the switch from one state to the other. The optical switch is configured with a fixed optical fiber and a movable optical fiber. The movable optical fiber is guided by various actuators in conjunction with a latching mechanism that configure the switch in one position that corresponds to the on state and in another position that corresponds to the off state.

Garcia, Ernest J; Polosky, Marc A

2013-05-21

85

The induction of the oxidative burst in Elodea densa by sulfhydryl reagents is independent of the inhibiting action of these reagents on photosynthesis  

Microsoft Academic Search

The sulfhydryl group-reagents NEM (N-ethylmaleimide), p-CMBS (parachloromercurybenzenesulfonate), Ag+ and Cu2+ inhibit very rapidly and drastically photosynthetic O2 evolution inElodea densa leaves. This effect has been compared with that of the same reagents in inducing in non illuminated leaves a strong increase\\u000a of O2 consumption (oxygen burst), presumably due to activation of some plasma membrane redox systems. The results suggest that

Francesco Albergoni; Pietro Rocco; Mario Bellando; Silvano Sacco; Maria Teresa Marrè; E. Marrè

1996-01-01

86

Pretreatment Based on Sulfhydryl Cotton Fiber Adsorption and Toluene Extraction for the Determination of Alkyl-Mercury Compounds in Aqueous Samples Using Capillary GC  

Microsoft Academic Search

A methodology of pretreatment for the determination of alkyl-mercury compounds in aqueous samples using capillary gas chromatography (GC) was described, which mainly comprised of sulfhydryl cotton fiber (SCF) adsorption\\/NaCl-HCl elution\\/toluene extraction. The factors with regard to the effect of adsorption were evaluated, which involved pH value and flow through SCF tube. The other factors affecting pretreatment were optimized, including eluent

Rongfang Yuan; Beihai Zhou; Hui Qi; Huimin Yin

2009-01-01

87

HSF1-Dependent Upregulation of Hsp70 by Sulfhydryl-Reactive Inducers of the KEAP1/NRF2/ARE Pathway  

PubMed Central

SUMMARY The KEAP1/NRF2/ARE pathway and the heat shock response are inducible cytoprotective systems regulated by transcription factors NRF2 and HSF1, respectively. We report that structurally distinct small molecule NRF2 activators, all of which react with sulfhydryl groups but differ in potency by 15,000-fold, upregulate Hsp70, a prototypic HSF1-dependent gene. Hsp70 upregulation requires HSF1 but is NRF2 independent. We further demonstrate that a sulfoxythiocarbamate inducer conjugates to the negative regulator of HSF1, Hsp90. The differential concentration dependence of the two responses suggests that activation of NRF2 precedes that of HSF1: the KEAP1/NRF2/ARE pathway is at the fore-front of cellular defense, protecting against instant danger; the heat shock response closely follows to resolve subsequent potentially devastating damage, saving the proteome. This uncovered duality undoubtedly contributes to the cytoprotective effects of such molecules in models of carcinogenesis, cardiovascular disease, and neurodegeneration. PMID:22118669

Zhang, Ying; Ahn, Young-Hoon; Benjamin, Ivor J.; Honda, Tadashi; Hicks, Ronald J.; Calabrese, Vittorio; Cole, Philip A.; Dinkova-Kostova, Albena T.

2012-01-01

88

Surface modification of titanium substrates with silver nanoparticles embedded sulfhydrylated chitosan/gelatin polyelectrolyte multilayer films for antibacterial application.  

PubMed

To develop Ti implants with potent antibacterial activity, a novel "sandwich-type" structure of sulfhydrylated chitosan (Chi-SH)/gelatin (Gel) polyelectrolyte multilayer films embedding silver (Ag) nanoparticles was coated onto titanium substrate using a spin-assisted layer-by-layer assembly technique. Ag ions would be enriched in the polyelectrolyte multilayer films via the specific interactions between Ag ions and -HS groups in Chi-HS, thus leading to the formation of Ag nanoparticles in situ by photo-catalytic reaction (ultraviolet irradiation). Contact angle measurement and field emission scanning electron microscopy equipped with energy dispersive X-ray spectroscopy were employed to monitor the construction of Ag-containing multilayer on titanium surface, respectively. The functional multilayered films on titanium substrate [Ti/PEI/(Gel/Chi-SH/Ag) n /Gel] could efficiently inhibit the growth and activity of Bacillus subtitles and Escherichia coli onto titanium surface. Moreover, studies in vitro confirmed that Ti substrates coating with functional multilayer films remained the biological functions of osteoblasts, which was reflected by cell morphology, cell viability and ALP activity measurements. This study provides a simple, versatile and generalized methodology to design functional titanium implants with good cyto-compatibility and antibacterial activity for potential clinical applications. PMID:24664672

Li, Wen; Xu, Dawei; Hu, Yan; Cai, Kaiyong; Lin, Yingcheng

2014-06-01

89

Uptake of {sup 10}B in gliosarcomas following the injection of gluthathione monoethyl ester and sulfhydryl borane  

SciTech Connect

The sulfhydryl borane Na{sub 2}{sup 10}B{sub 12}H{sub 11}SH (BSH) was developed as a capture agent for BNCT about 20 years ago and is the compound currently used clinically in Japan for BNCT of malignant brain tumors. Tumor {sup 10}B concentrations following the infusion of the oxidized BSH, a disulfide dimer (Na{sub 4}{sup 10}B{sub 24}H{sub 22}S{sub 2}), are nearly twice those obtained following administration of equal amounts of boron as BSH. Also, the rate of decrease of tumor {sup 10}B concentration is slower after dimer infusion than after BSH infusion. When BNCT was administered to rats bearing intracerebral gliosarcomas, the animals infused with dimer had a significant longer median survival time. Dimer, on the other hand, induces a moderately severe, but reversible, hepatotoxicity which may complicate its use in humans. Intracellular glutathione plays an important role in defense against radical-mediated tissue injury. Glutathione monoesters have been reported to have a protective effective on cisplatin toxicity and on radical-induced acute pancreatitis. We investigated the possibility of reducing dimer-induced hepatotoxicity by pre-administration of GSH-ME. The results indicate that not only does the pre-administration of GSH-ME markedly reduce dimer-induced hepatotoxicity, but also results in nearly a doubling of tumor boron concentration. Furthermore, GSH-ME markedly increases tumor boron uptake and retention following administration of BSH.

Joel, D.D.; Slatkin, D.N.; Coderre, J.A.

1992-12-31

90

Uptake of [sup 10]B in gliosarcomas following the injection of gluthathione monoethyl ester and sulfhydryl borane  

SciTech Connect

The sulfhydryl borane Na[sub 2][sup 10]B[sub 12]H[sub 11]SH (BSH) was developed as a capture agent for BNCT about 20 years ago and is the compound currently used clinically in Japan for BNCT of malignant brain tumors. Tumor [sup 10]B concentrations following the infusion of the oxidized BSH, a disulfide dimer (Na[sub 4][sup 10]B[sub 24]H[sub 22]S[sub 2]), are nearly twice those obtained following administration of equal amounts of boron as BSH. Also, the rate of decrease of tumor [sup 10]B concentration is slower after dimer infusion than after BSH infusion. When BNCT was administered to rats bearing intracerebral gliosarcomas, the animals infused with dimer had a significant longer median survival time. Dimer, on the other hand, induces a moderately severe, but reversible, hepatotoxicity which may complicate its use in humans. Intracellular glutathione plays an important role in defense against radical-mediated tissue injury. Glutathione monoesters have been reported to have a protective effective on cisplatin toxicity and on radical-induced acute pancreatitis. We investigated the possibility of reducing dimer-induced hepatotoxicity by pre-administration of GSH-ME. The results indicate that not only does the pre-administration of GSH-ME markedly reduce dimer-induced hepatotoxicity, but also results in nearly a doubling of tumor boron concentration. Furthermore, GSH-ME markedly increases tumor boron uptake and retention following administration of BSH.

Joel, D.D.; Slatkin, D.N.; Coderre, J.A.

1992-01-01

91

Hepatic cysteamine and non-protein sulfhydryl levels following cystamine or cysteamine treatment of galactosamine-poisoned rats  

SciTech Connect

Hepatic cysteamine and non-protein sulfhydryl (NPSH) levels were determined in galactosamine (GAL)-poisoned rats following hepatoprotective cystamine or cysteamine treatments to determine whether alterations of hepatic NPSH status could contribute to their observed protective actions. D(+)-Galactosamine HC1 (400 mg/kg, ip) was administered to male Sprague-Dawley rats at 8 pm. Cystamine diHC1 (300 mg/kg, po) or cysteamine HC1 (170 mg/kg, ip) were administered 12 hr after GAL. Hepatic NPSH levels were determined using Ellman's reagent. Hepatic cysteamine levels were determined by separating NPSH Ellman's derivatives by reversed phase HPLC. Cystamine and cysteamine caused transient elevation of NPSH levels of 1-2 nanomoles/mg liver which correlated with the presence of 1-2 nanomoles of cysteamine/mg liver. However, neither cystamine nor cysteamine prevented NPSH levels from falling to 3 nanomoles/mg tissue 24 hr after GAL. Hepatoprotective treatments did not affect long term NPSH status in GAL-poisoned rats. However, transient NPSH increases, due to the intrahepatic presence of cysteamine, may contribute to the therapeutic effects of these hepatoprotective agents.

MacDonald, J.R.; Gandolfi, A.J.; Sipes, I.G.

1985-01-01

92

Eosinophil peroxidase oxidation of thiocyanate. Characterization of major reaction products and a potential sulfhydryl-targeted cytotoxicity system.  

PubMed

Although the pseudohalide thiocyanate (SCN(-)) is the preferred substrate for eosinophil peroxidase (EPO) in fluids of physiologic halide composition, the product(s) of this reaction have not been directly identified, and mechanisms underlying their cytotoxic potential are poorly characterized. We used nuclear magnetic resonance spectroscopy (NMR), electrospray ionization mass spectrometry, and quantitative chemical analysis to identify the principal reaction products of both the EPO/SCN(-)/H(2)O(2) system and activated eosinophils as roughly equimolar amounts of OSCN(-) (hypothiocyanite) and OCN(-) (cyanate). Red blood cells exposed to increasing concentrations of OSCN(-)/OCN(-) are first depleted of glutathione, after which glutathione S-transferase and glyceraldehyde-3-phosphate dehydrogenase then ATPases undergo sulfhydryl (SH) reductant-reversible inactivation before lysing. OSCN(-)/OCN(-) inactivates red blood cell membrane ATPases 10-1000 times more potently than do HOCl, HOBr, and H(2)O(2). Exposure of glutathione S-transferase to [(14)C]OSCN(-)/OCN(-) causes SH reductant-reversible disulfide bonding and covalent isotope labeling. We propose that EPO/SCN(-)/H(2)O(2) reaction products comprise a potential SH-targeted cytotoxic system that functions in striking contrast to HOCl, the highly but relatively indiscriminantly reactive product of the neutrophil myeloperoxidase system. PMID:11013238

Arlandson, M; Decker, T; Roongta, V A; Bonilla, L; Mayo, K H; MacPherson, J C; Hazen, S L; Slungaard, A

2001-01-01

93

The Role of Sulfhydryl Reactivity of Small Molecules for the Activation of the KEAP1/NRF2 Pathway and the Heat Shock Response  

PubMed Central

The KEAP1/NRF2 pathway and the heat shock response are two essential cytoprotective mechanisms that allow adaptation and survival under conditions of oxidative, electrophilic, and thermal stress by regulating the expression of elaborate networks of genes with versatile protective functions. The two pathways are independently regulated by the transcription factor nuclear factor-erythroid 2 p45-related factor 2 (NRF2) and heat shock factor 1 (HSF1), respectively. The activity of these transcriptional master regulators increases during conditions of stress and also upon encounter of small molecules (inducers), both naturally occurring as well as synthetically produced. Inducers have a common chemical property: the ability to react with sulfhydryl groups. The protein targets of such sulfhydryl-reactive compounds are equipped with highly reactive cysteine residues, which serve as sensors for inducers. The initial cysteine-sensed signal is further relayed to affect the expression of large networks of genes, which in turn can ultimately influence complex cell fate decisions such as life and death. The paper summarizes the multiple lines of experimental evidence demonstrating that the reactivity with sulfhydryl groups is a major determinant of the mechanism of action of small molecule dual activators of the KEAP1/NRF2 pathway and the heat shock response. PMID:24278719

Dinkova-Kostova, Albena T.

2012-01-01

94

Self-organized atomic switch networks  

NASA Astrophysics Data System (ADS)

The spontaneous emergence of complex behavior in dynamical systems occurs through the collective interaction of nonlinear elements toward a highly correlated, non-equilibrium critical state. Criticality has been proposed as a model for understanding complexity in systems whose behavior can be approximated as a state lying somewhere between order and chaos. Here we present unique, purpose-built devices, known as atomic switch networks (ASN), specifically designed to generate the class of emergent properties which underlie critical dynamics in complex systems. The network is an open, dissipative system comprised of highly interconnected (?109/cm2) atomic switch interfaces wired through the spontaneous electroless deposition of metallic silver fractal architectures. The functional topology of ASN architectures self-organizes to produce persistent critical dynamics without fine-tuning, indicating a capacity for memory and learning via persistent critical states toward potential utility in real-time, neuromorphic computation.

Stieg, Adam Z.; Avizienis, Audrius V.; Sillin, Henry O.; Martin-Olmos, Cristina; Lam, Miu-Ling; Aono, Masakazu; Gimzewski, James K.

2014-01-01

95

Optically Controlled 22 Switching Cell for Packet-Switched Networks  

E-print Network

Optically Controlled 2Ã?2 Switching Cell for Packet-Switched Networks C. C. Lee1 , L. F. K. Lui1-optical switches for all-optical packet-switched networks. All-optical packet-switching is performed based-optical packet add-drop for an all-optical packet-switched network [3]. In this paper, we demonstrated a 10 Gb

Wai, Ping-kong Alexander

96

Triggered plasma opening switch  

SciTech Connect

A triggerable opening switch for a very high voltage and current pulse includes a transmission line extending from a source to a load and having an intermediate switch section including a plasma for conducting electrons between transmission line conductors and a magnetic field for breaking the plasma conduction path and magnetically insulating the electrons when it is desired to open the switch.

Mendel, Clifford W. (Albuquerque, NM)

1988-01-01

97

Triggered plasma opening switch  

SciTech Connect

A triggerable opening switch for a very high voltage and current pulse includes a transmission line extending from a source to a load and having an intermediate switch section including a plasma for conducting electrons between transmission line conductors and a magnetic field for breaking the plasma conduction path and magnetically insulating the electrons when it is desired to open the switch.

Mendel, C.W.

1988-02-23

98

Apollo Ring Optical Switch  

SciTech Connect

An optical switch was designed, built, and installed at Sandia National Laboratories in Albuquerque, New Mexico, to facilitate the integration of two Apollo computer networks into a single network. This report presents an overview of the optical switch as well as its layout, switch testing procedure and test data, and installation.

Maestas, J.H.

1987-03-01

99

Fast electroholographic switching.  

PubMed

Electroholographic switching with a rise time of 13 ns is henceforth presented. The switching was demonstrated in a potassium lithium tantalate crystal doped with copper and titanium with Tc=10 degrees C. The crystal was operated at 17 degrees C. The switching operation was done in the g11/g12 configuration, in which the Bragg condition remains fulfilled at all levels of the applied field. As electroholography is a wavelength-selective switching method, this opens the way for implementing optical packet switching and fast wavelength addressing schemes in optical fiber networks that apply wavelength division multiplexing. PMID:19183656

Sapiens, Noam; Weissbrod, Aharon; Agranat, Aharon J

2009-02-01

100

Photoconductive power switches  

SciTech Connect

This paper outlines the advantages and the potential of photoconductive switches applied to high-power systems. The photoconductive effect can be used to switch large amounts of energy by changing the conductivity of a solid-state circuit element many orders of magnitude with a high-power laser. The simplicity of these devices offers many advantages in high-power applications when combined with high-power pulsed lasers. The surge capability, the switched energy gain, and the maximum average power for photoconductive power switches are discussed. In addition, the results of a 100-kV, 100-MW photoconductive switch experiment transferring 20 J in 200 ns are presented.

Nunnally, W.C.; Hammond, R.B.

1983-01-01

101

Oxidative Protein Folding in vitro: a Study of the Cooperation between Quiescin-sulfhydryl Oxidase and Protein Disulfide Isomerase  

PubMed Central

The flavin-dependent Quiescin-sulfhydryl oxidase (QSOX) inserts disulfide bridges into unfolded reduced proteins with the reduction of molecular oxygen to form hydrogen peroxide. This work investigates how QSOX and protein disulfide isomerase (PDI) cooperate in vitro to generate native pairings in two unfolded reduced proteins: ribonuclease A (RNase: 4 disulfide bonds and 105 disulfide isomers of the fully oxidized protein) and avian riboflavin binding protein (RfBP: 9 disulfide bonds and greater than 34 million corresponding disulfide pairings). Experiments combining avian or human QSOX with up to 200 ?M of avian or human reduced PDI show that the isomerase is not a significant substrate of QSOX. Both reduced RNase and RfBP can be efficiently refolded in an aerobic solution containing micromolar concentrations of reduced PDI and nanomolar levels of QSOX without any added oxidized PDI or glutathione redox buffer. Refolding of RfBP is followed continuously using the complete quenching of the fluorescence of free riboflavin that occurs on binding to apo-RfBP. The rate of refolding is half-maximal at 30 ?M reduced PDI when 1 ?M of the reduced client protein is used in the presence of 30 nM QSOX. The use of high concentrations of PDI, in considerable excess over the folding protein client, reflect the concentration prevailing in the lumen of the endoplasmic reticulum and allow the redox poise of these in vitro experiments to be set with oxidized and reduced PDI. In the absence of either QSOX or redox buffer, the fastest refolding of RfBP is accomplished with excess reduced PDI and just enough oxidized PDI to generate 9- disulfides in the protein client. These in vitro experiments are discussed in terms of current models for oxidative folding in the endoplasmic reticulum. PMID:18937500

Rancy, Pumtiwitt C.; Thorpe, Colin

2010-01-01

102

Effects of sulfhydryl compounds, carbohydrates, organic acids, and sodium sulfite on the formation of lysinoalanine in preserved egg.  

PubMed

To identify inhibitors for lysinoalanine formation in preserved egg, sulfhydryl compounds (glutathione, L-cysteine), carbohydrates (sucrose, D-glucose, maltose), organic acids (L-ascorbic acid, citric acid, DL-malic acid, lactic acid), and sodium sulfite were individually added at different concentrations to a pickling solution to prepare preserved eggs. Lysinoalanine formation as an index of these 10 substances was determined. Results indicate that glutathione, D-glucose, maltose, L-ascorbic acid, citric acid, lactic acid, and sodium sulfite all effectively diminished lysinoalanine formation in preserved egg albumen and yolk. When 40 and 80 mmol/L of sodium sulfite, citric acid, L-ascorbic acid, and D-glucose were individually added into the pickling solution, the inhibition rates of lysinoalanine in the produced preserved egg albumen and yolk were higher. However, the attempt of minimizing lysinoalanine formation was combined with the premise of ensuring preserved eggs quality. Moreover, the addition of 40 and 80 mmol/L of sodium sulfite, 40 and 80 mmol/L of D-glucose, 40 mmol/L of citric acid, and 40 mmol/L of L-ascorbic acid was optimal to produce preserved eggs. The corresponding inhibition rates of lysinoalanine in the albumen were approximately 76.3% to 76.5%, 67.6% to 67.8%, 74.6%, and 74.6%, and the corresponding inhibition rates of lysinoalanine in the yolk were about 68.7% to 69.7%, 50.6% to 51.8%, 70.4%, and 57.8%. It was concluded that sodium sulfite, D-glucose, L-ascorbic, and citric acid at suitable concentrations can be used to control the formation of lysinoalanine during preserved egg processing. PMID:25047093

Luo, Xu-Ying; Tu, Yong-Gang; Zhao, Yan; Li, Jian-Ke; Wang, Jun-Jie

2014-08-01

103

Studies on the plasma membrane H sup + -ATPase of oat roots: Preparation and assay, cytological localization, and sulfhydryl chemistry  

SciTech Connect

Biochemical and cytological studies were performed on the plasma membrane proton pump (H{sup +}-ATPase) of oat roots (Avena sativa cv. Stout). H{sup +}-ATPase activity in oat root plasma membranes is inhibited by N-ethylmaleimide (NEM), a covalent modifier of protein sulfhydryl groups. The rate of inhibition is reduced in the presence of ADP or MgADP. An M{sub r} = 100,000 plasma membrane polypeptide showed reduced labelling by ({sup 3}H)NEM in the presence of ADP. When tryptic peptides from ({sup 3}H)NEM-labeled M{sub r} = 100,000 polypeptide were separated by reverse-phase high-pressure liquid chromatography (HPLC), only one radioactive peak consistently showed labeling in the presence of ADP. In order to determine the location and identity of the NEM-reactive residue, the radioactive peptide in this peak was further purified by HPLC. The amino acid sequence(s) in the resulting sample were then determined by Edman degradation on an automated gas-phase sequenator. The PTH-amino acids released at each cycle of the degradation were separated by HPLC. Analysis of the chromatograms suggested that the radio-labeled residue was located in a peptide of sequence V-E-N-Q-D-A-I-D-A-C{sup *}-M-V-G-M-L-A-D-P-K. The NEM-reactive residue was cysteine, based on the retention time of the radioactivity released. The ATP-hydrolyzing activity observed in electron micrographs by lead-precipitation of enzymically released inorganic phosphate was compared with that observed in in vitro assays of the soluble and plasma membrane fractions of oat root homogenates. Although an ATP-hydrolyzing activity was observed on the plasma membrane in the electron micrographs, its substrate specificity and inhibitor sensitivity was identical to that observed for phosphatase activity.

Katz, D.B.

1989-01-01

104

Switching Languages, Switching Palabras (Words): An Electrophysiological Study of Code Switching  

Microsoft Academic Search

Switching languages has often been associated with a processing cost. In this study, the authors used event-related potentials to compare switches between two languages with within-language lexical switches as bilinguals read for comprehension. Stimuli included English sentences and idioms ending either with the expected English words, their Spanish translations (code switches), or English synonyms (lexical switches). As expected, lexical switches

Eva M. Moreno; Kara D. Federmeier; Marta Kutas

2002-01-01

105

Task switching: a high-density electrical mapping study  

Microsoft Academic Search

Flexibly switching between tasks is one of the paradigmatic functions of so-called “executive control” processes. Neuroimaging studies have implicated both prefrontal and parietal cortical regions in the processing necessary to effectively switch task. Beyond their general involvement in this critical function, however, little is known about the dynamics of processing across frontal and parietal regions. For instance, it remains to

G. R. Wylie; D. C. Javitt; J. J. Foxea

2003-01-01

106

Optoelectronic techniques for broadband switching  

NASA Technical Reports Server (NTRS)

Optoelectronic switching employs a hybrid optical/electronic principle to perform the switching function and is applicable for either analog broadband or high-bit rate digital switching. The major advantages of optoelectronic switching include high isolation, low crosstalk, small physical size, light weight, and low power consumption. These advantages make optoelectronic switching an excellent candidate for on-board satellite switching. This paper describes a number of optoelectronic switching architectures. System components required for implementing these switching architectures are discussed. Performance of these architectures are evaluated by calculating their crosstalk, isolation, insertion loss, matrix size, drive power, throughput, and switching speed. Technologies needed for monolithic optoelectronic switching are also identified.

Su, S. F.; Jou, L.; Lenart, J.

1988-01-01

107

Effective switching frequency multiplier inverter  

DOEpatents

A switching frequency multiplier inverter for low inductance machines that uses parallel connection of switches and each switch is independently controlled according to a pulse width modulation scheme. The effective switching frequency is multiplied by the number of switches connected in parallel while each individual switch operates within its limit of switching frequency. This technique can also be used for other power converters such as DC/DC, AC/DC converters.

Su, Gui-Jia (Oak Ridge, TN); Peng, Fang Z. (Okemos, MI)

2007-08-07

108

Alternatives to switch-cost scoring in the task-switching paradigm: their reliability and increased validity.  

PubMed

In the task-switching paradigm, the latency switch-cost score-the difference in mean reaction time between switch and nonswitch trials-is the traditional measure of task-switching ability. However, this score does not reflect accuracy, where switch costs may also emerge. In two experiments that varied in response deadlines (unlimited vs. limited time), we evaluated the measurement properties of two traditional switch-cost scoring methods (the latency switch-cost score and the accuracy switch-cost score) and three alternatives (a rate residual score, a bin score, and an inverse efficiency score). Scores from the rate residual, bin score, and inverse efficiency methods had comparable reliability for latency switch-cost scores without response deadlines but were more reliable than latency switch-cost scores when higher error rates were induced with a response deadline. All three alternative scoring methods appropriately accounted for differences in accuracy switch costs when higher error rates were induced, whereas pure latency switch-cost scores did not. Critically, only the rate residual and bin score methods were more valid indicators of task-switching ability; they demonstrated stronger relationships with performance on an independent measure of executive functioning (the antisaccade analogue task), and they allowed the detection of larger effect sizes when examining within-task congruency effects. All of the three alternative scoring methods provide researchers with a better measure of task-switching ability than do traditional scoring methods, because they each simultaneously account for latency and accuracy costs. Overall, the three alternative scoring methods were all superior to the traditional latency switch-cost scoring method, but the strongest methods were the rate residual and bin score methods. PMID:24356991

Hughes, Meredith M; Linck, Jared A; Bowles, Anita R; Koeth, Joel T; Bunting, Michael F

2014-09-01

109

AC magnetohydrodynamic microfluidic switch  

SciTech Connect

A microfluidic switch has been demonstrated using an AC Magnetohydrodynamic (MHD) pumping mechanism in which the Lorentz force is used to pump an electrolytic solution. By integrating two AC MHD pumps into different arms of a Y-shaped fluidic circuit, flow can be switched between the two arms. This type of switch can be used to produce complex fluidic routing, which may have multiple applications in {micro}TAS.

Lemoff, A V; Lee, A P

2000-03-02

110

Thermally actuated thermionic switch  

SciTech Connect

A thermally actuated thermionic switch which responds to an increase of temperature by changing from a high impedance to a low impedance at a predictable temperature set point. The switch has a bistable operation mode switching only on temperature increases. The thermionic material may be a metal which is liquid at the desired operation temperature and held in matrix in a graphite block reservoir, and which changes state (ionizes, for example) so as to be electrically conductive at a desired temperature.

Barrus, Donald M. (San Jose, CA); Shires, Charles D. (San Jose, CA)

1988-01-01

111

Modeling of fast switching processes in nanoscale spin valves  

NASA Astrophysics Data System (ADS)

Braganca et al. [Appl. Phys. Lett. 87, 112507 (2005)] fabricated spin valves (permalloy/copper/permalloy) with elliptical cross-sectional area designed to reduce the critical currents for spin-transfer switching maintaining its thermal stability. We performed a numerical experiment in that spin valve to study how the switching time is affected by saturation magnetization and damping. Those parameters can be experimentally tuned by changing the alloy percentage or by introducing impurities. We find out the switching time and the switching mechanism are independent of those parameters for nanosecond reversal processes.

Carpentieri, M.; Finocchio, G.; Torres, L.; Azzerboni, B.

2008-04-01

112

Relationship of membrane-bound sulfhydryl groups to vitamin D-stimulated uptake of ( sup 75 Se)Selenite by the brush border membrane vesicles from chick duodenum  

SciTech Connect

The uptake of selenite by purified brush border membrane vesicles isolated from duodena of rachitic or vitamin D-treated chicks was studied by using radioactive selenite and a rapid filtration technique. Cholecalciferol treatment (500 IU at 72 h) significantly enhanced selenite uptake, a response that decreased when the vesicles were stored at room temperature for 2.5 h prior to the uptake measurement. Preincubation of the vesicles in 1.0 mmol/L H2O2 reduced (75Se)selenite uptake, indicating the involvement of oxidizable groups in the uptake reaction. Iodoacetic acid (IAA), a sulfhydryl-blocking reagent, at 1-2 mmol/L concentration eliminated the difference in selenite uptake due to cholecalciferol and had no effect on vesicles from rachitic animals. A higher concentration of IAA (10 mmol/L) enhanced selenite uptake manyfold and increased the absolute difference due to cholecalciferol treatment. Single intravenous doses of 100 IU cholecalciferol, 100 IU ergocalciferol, or 0.1 micrograms 1,25-dihydroxycholecalciferol also stimulated selenite uptake, suggesting a general response to vitamin D compounds. Normal animals given a single dose of 1,25-dihydroxycholecalciferol 12 h prior to killing also responded. Treatments that enhanced the uptake of (75Se)selenite also increased the amount of membrane-bound sulfhydryl groups, suggesting the involvement of membrane-bound sulfhydryl groups in the vitamin D response. A significant increase in selenite uptake by intravenous 1,25-dihydroxycholecalciferol occurred within 10 min. This rapid effect provides a new tool to probe early biochemical effects of vitamin D on intestinal epithelium.

Mykkanen, H.M.; Wasserman, R.H. (Cornell Univ., Ithaca, NY (USA))

1990-08-01

113

Alarm toe switch  

DOEpatents

An alarm toe switch inserted within a shoe for energizing an alarm circuit n a covert manner includes an insole mounting pad into which a miniature reed switch is fixedly molded. An elongated slot perpendicular to the reed switch is formed in the bottom surface of the mounting pad. A permanent cylindrical magnet positioned in the forward portion of the slot with a diameter greater than the pad thickness causes a bump above the pad. A foam rubber block is also positioned in the slot rearwardly of the magnet and holds the magnet in normal inoperative relation. A non-magnetic support plate covers the slot and holds the magnet and foam rubber in the slot. The plate minimizes bending and frictional forces to improve movement of the magnet for reliable switch activation. The bump occupies the knuckle space beneath the big toe. When the big toe is scrunched rearwardly the magnet is moved within the slot relative to the reed switch, thus magnetically activating the switch. When toe pressure is released the foam rubber block forces the magnet back into normal inoperative position to deactivate the reed switch. The reed switch is hermetically sealed with the magnet acting through the wall so the switch assembly S is capable of reliable operation even in wet and corrosive environments.

Ganyard, Floyd P. (Albuquerque, NM)

1982-01-01

114

Effects of chemical modification of amino and sulfhydryl groups on K ATP channel function and sulfonylurea binding in CRI-G1 insulin-secreting cells  

Microsoft Academic Search

The effects of several group-specific chemical reagents were examined upon the activity of the ATP-sensitive potassium (KATP) channel in the CRI-G1 insulin-secreting cell line. Agents which interact with the sulfhydryl moiety (including 1 mM N-ethylmaleimide (NEM), 1 mM 5,5'-dithio-bis-(2-nitrobenzoic acid) (DNTB) and 1 mmo-iodobenzoate) produced an irreversible inhibition of KATP channel activity when applied to the intracellular surface of excised

K. Lee; S. E. Ozanne; C. N. Hales; M. L. J. Ashford

1994-01-01

115

The Respiratory Burst and Electrolyte Leakage Induced by Sulfhydryl Blockers in Egeria densa Leaves Are Associated with H2O2 Production and Are Dependent on Ca2+ Influx1  

PubMed Central

In leaves of Egeria densa Planchon, N-ethylmaleimide (NEM) and other sulfhydryl-binding reagents induce a temporary increase in nonmitochondrial respiration (?QO2) that is inhibited by diphenylene iodonium and quinacrine, two known inhibitors of the plasma membrane NADPH oxidase, and are associated with a relevant increase in electrolyte leakage (M. Bellando, S. Sacco, F. Albergoni, P. Rocco, M.T. Marré [1997] Bot Acta 110: 388–394). In this paper we report data indicating further analogies between the oxidative burst induced by sulfhydryl blockers in E. densa and that induced by pathogen-derived elicitors in animal and plant cells: (a) NEM- and Ag+-induced ?QO2 was associated with H2O2 production and both effects depended on the presence of external Ca2+; (b) Ca2+ influx was markedly increased by treatment with NEM; (c) the Ca2+ channel blocker LaCl3 inhibited ?QO2, electrolyte release, and membrane depolarization induced by the sulfhydryl reagents; and (d) LaCl3 also inhibited electrolyte leakage induced by the direct infiltration of the leaves with H2O2. These results suggest a model in which the interaction of sulfhydryl blockers with sulfhydryl groups of cell components would primarily induce an increase in the Ca2+ cytosolic concentration, followed by membrane depolarization and activation of a plasma membrane NADPH oxidase. This latter effect, producing active oxygen species, might further influence plasma membrane permeability, leading to the massive release of electrolytes from the tissue. PMID:9847112

Marre, Maria Teresa; Amicucci, Enrica; Zingarelli, Luisa; Albergoni, Francesco; Marre, Erasmo

1998-01-01

116

Redundant control of the Caenorhabditis elegans sperm oocyte switch by PUF-8 and FBF-1,  

E-print Network

is also critical for the hermaphrodite sperm oocyte switch. Most puf-8 mutant hermaphrodites make both-1 puf-8 double mutants fail in the hermaphrodite sperm oocyte switch. Therefore, puf-8 and fbf-1 act- rhabditis elegans sperm oocyte switch. C. elegans can exist as either a self-fertile hermaphrodite or a male

Kimble, Judith

117

Plasma Opening Switch Experiments On Hawk With An E-beam Diode Load  

Microsoft Academic Search

Successful application of inductive energy storage depends critically on the performance of the opening switch. The new Hawk generator at NRL~ is used in plasma opening switch (POS) experiments in the 1-ps conduction time regime to study lonq conduction time Pos physics. In this experiment, different POS configurations were used, including various switch to load distances and different cathode center

P. J. Goodrich; J. R. Boller; R. J. Commisso; D. D. Hinshelwood; J. C. Kellogg; B. V. Weber

1991-01-01

118

Reaction of cyclohexylamine with hypochlorite and enhancement of oxidation of plasma sulfhydryl groups by hypochlorite in vitro.  

PubMed

In this study we investigated the reaction of cyclamate and its major metabolite, cyclohexylamine (CyhNH2), with NaOCl. NaOCl at 100 microM was allowed to react with various concentrations of cyclamate and CyhNH2, and the reactivity was compared with those of reduced glutathione (GSH) and ascorbic acid. The results showed that CyhNH2 was less reactive with NaOCl than GSH but was slightly more reactive than ascorbic acid at concentrations below 50 microM. CyhNH2 at 75 and 100 microM did not further decrease NaOCl. Cyclamate was much less reactive than CyhNH2, with only 43% loss in NaOCl at 100 microM cyclamate. When human blood plasma was incubated with 0.75 microM NaOCl, inclusion of CyhNH2 enhanced oxidation of sulfhydryl groups in a concentration-dependent manner, with complete oxidation of SH groups at 7.5 mM CyhNH2. Cyclamate had no effect. This enhancement by CyhNH2 suggests the formation of reactive products from the reaction of CyhNH2 with NaOCl. Absorption spectra demonstrated that reaction of CyhNH2 with NaOCl at pH 7.4 produced N-monochloramine, as evidenced by the appearance of a new peak at 245 nm and by the disappearance of the 292-nm peak of NaOCl. Cyclamate, which contains a sulfamic acid instead of a primary amine, also reacted with NaOCl at pH 7.4, but the reaction was much less pronounced and the product was probably not monochloramine since the peak was at 270 nm rather than at 245 nm. Because cyclamate is an important sweetener in many countries for people with diabetes mellitus, the possibility exists that CyhNH2 may enhance oxidation of important proteins by HOCl/OCl-. PMID:9737422

Hu, M L; Tsai, H H

1998-01-01

119

Elevated Transcription of the Gene QSOX1 Encoding Quiescin Q6 Sulfhydryl Oxidase 1 in Breast Cancer  

PubMed Central

The q arm of chromosome 1 is frequently amplified at the gene level in breast cancer. Since the significance of this is unclear we investigated whether 1q genes are overexpressed in this disease. The cDNA levels of 1q-located genes were analysed in a search for overexpressed genes. 26 genes mapping to the 1q arm show highly significant (P?0.01) overexpression of transcripts in breast cancer compared to normal breast tissue. Amongst those showing the highest levels of overexpression in both expressed sequence tag (EST) and serial analysis of gene expression (SAGE) databases was enzyme quiescin Q6 sulfhydryl oxidase 1 (QSOX1). We investigated QSOX1 cDNA derived from T47D breast carcinoma cells by RT-PCR and 3?-RACE PCR and identified a novel extended form of QSOX1 transcript, containing a long 3?UTR, nearly double the size of the previously reported QSOX1 cDNA, and confirmed its 3? end nucleotide sequence using RACE-PCR. We also used quantitative real-time PCR to analyse a panel of cDNAs derived from 50 clinically-graded normal and malignant breast tissue samples for the expression of QSOX1 mRNAs. QSOX1 transcription was elevated in an increasing proportion in the grade 2 and grade 3 tumours (graded according to the Nottingham prognostic index), with 10 of the 15 grade 3 tumours (67%) examined exceeding the normal range. There was a significant correlation between relative transcript level and clinical grade (P?0.01) for all qPCR primer sets tested. QSOX1 mRNA levels, based on SAGE expression data, did not correlate with either Estrogen Receptor (ER) or Epidermal Growth Factor Receptor 2 (ErbB-2 or HER2/neu) expression. Our data indicate that QSOX1 is a potential new prognostic marker which may prove of use in the staging of breast tumours and the stratification of breast cancer patients. PMID:23460839

Soloviev, Mikhail; Esteves, Michelle P.; Amiri, Fakhria; Crompton, Mark R.; Rider, Christopher C.

2013-01-01

120

Critical pulse power components  

SciTech Connect

Critical components for pulsed power conditioning systems will be reviewed. Particular emphasis will be placed on those components requiring significant development efforts. Capacitors, for example, are one of the weakest elements in high-power pulsed systems, especially when operation at high-repetition frequencies for extended periods of time are necessary. Switches are by far the weakest active components of pulse power systems. In particular, opening switches are essentially nonexistent for most applications. Insulaton in all systems and components requires development and improvement. Efforts under way in technology base development of pulse power components will be discussed.

Sarjeant, W.J.; Rohwein, G.J.

1981-01-01

121

Task switching and the measurement of “switch costs”  

Microsoft Academic Search

The measurement of “switch costs” is held to be of interest because, as is widely believed, they may reflect the control\\u000a processes that are engaged when subjects switch between two (or more) competing tasks. [In task-switching experiments, the\\u000a reaction time (RT) switch cost is typically measured as the difference in RT between switch and non-switch (repeat) trials.]\\u000a In this report

Glenn Wylie; Alan Allport

2000-01-01

122

Photonic switching fabrics  

Microsoft Academic Search

The strengths and limitations of the photonic technology are reviewed, beginning with the temporal bandwidth limitations of photonic devices and then focusing on spatial bandwidth, commonly referred to as the parallelism of optics, and how it can be used in photonic fabrics. Some of the proposed photonic switching fabrics that are based on guided-wave devices are discussed, comprising switching fabrics

H. Scott Hinton

1990-01-01

123

Novel RF MEMS Switches  

Microsoft Academic Search

This paper reviews three novel RF MEMS ohmic contact switches, each being designed for specific applications. All three were developed at Imperial College London. The first is a packaged single-pole double throw (SPDT) version intended for space applications, operating from DC to 6 GHz; the second is a single-pole single throw (SPST) switch for high power applications in the 40

S. Lucyszyn; S. Pranonsatit; J. Y. Choi; R. W. Moseley; E. M. Yeatman; A. S. Holmes

2007-01-01

124

Optical Label Switching Technologies for Optical Packet Switched Networks.  

E-print Network

??Optical packet switching (OPS) is the most prominent candidate transport solution that can seamlessly integrate electrical and optical layers by transferring certain switching functionality from… (more)

Chowdhury, Arshad M.

2006-01-01

125

Triggered plasma opening switch  

SciTech Connect

A triggerable plasma opening switch for connecting a megavolt, megampere power supply to a load is described comprising: cathode means having an input end, an output end, and a switch portion between the ends; anode means having an input end, an output end, and a switch portion between the ends and spaced from the switch portion of the cathode means by a gap; whereby the power supply is connectable between the input ends and the load is connectable between the output ends; plasma source means for filling the gap with a plasma for providing a current path for shorting current from the load; and triggering means for generating a magnetic field for controllably moving the plasma away from one of the anode or the cathode to generate an insulating gap and to block the electron flow across the gap, thereby opening the switch and permitting current to flow from the power supply to the load.

Mendel, C.W.

1988-02-23

126

The 3-(bromoacetamido)-propylamine hydrochloride: A novel sulfhydryl reagent and its future potential in the configurational study of S1-myosin  

NASA Technical Reports Server (NTRS)

Configurational study of S1-Myosin is an important step towards understanding force generation in muscle contraction. Previously reported NMR studies were corroborated. A new compound was synthesized, 3-(Bromoacetamido)-propylamine hydrochloride. Its potential as a sulfhydryl reagent provides an indirect but elegant approach towards future structural elucidation of S1-Myosin. The preliminary investigation has shown that this compound, BAAP, reacted with S1 in the absence of MgADP. The modified enzyme had a 2-fold increase in CaATPase activity and no detectable K-EDTA ATPase activity. Reaction of BAAP with S1 in the presence of MgADP resulted in a modified enzyme which retained a Ca-ATPase activity that was about 60 percent of the unmodified S1 and had essentially zero K-EDTA ATPase activity. Sulfhydryl titration indicated that about 1.5 and 3.5 SH groups per S1 molecule were blocked by BAAP in the absence and presence of MgADP, respectively. When coupled to a carboxyl group of EDTA, the resulting reagent could become a useful SH reagent in which chelated paramagnetic or luminescent lanthanide ions can be exploited to probe S1 conformation.

Sharma, Prasanta; Cheung, Herbert C.

1989-01-01

127

High temperature superconductor resistive switch characteristics  

SciTech Connect

High Temperature Superconductor (HTSc) will switch from the superconducting state to the normal resistive state when an intrinsic critical current density is exceeded. The authors have measured the transition characteristics for HTSc thin films forced into transition by the application of voltage driven overcurrents. These thin films were used in the development of prototype HTSc fault current limiting devices. The prototype fault current limiters have exhibited excellent performance, combining low insertion loss during normal current conditions with rapid response and minimization of fault currents. This paper describes the results of several subscale power applications experiments which have demonstrated the usefulness of these devices. Also presented is an experiment demonstrating active switching of the devices to the resistive state. These experimental results will benefit researchers considering the use of HTSc switches for active control of current.

Scholz, T.J.; Barber, J.P. [IAP Research, Inc., Dayton, OH (United States)] [IAP Research, Inc., Dayton, OH (United States)

1997-01-01

128

Sleep State Switching  

PubMed Central

We take for granted the ability to fall asleep or to snap out of sleep into wakefulness, but these changes in behavioral state require specific switching mechanisms in the brain that allow well-defined state transitions. In this review, we examine the basic circuitry underlying the regulation of sleep and wakefulness, and discuss a theoretical framework wherein the interactions between reciprocal neuronal circuits enable relatively rapid and complete state transitions. We also review how homeostatic, circadian, and allostatic drives help regulate sleep state switching, and discuss how breakdown of the switching mechanism may contribute to sleep disorders such as narcolepsy. PMID:21172606

Saper, Clifford B.; Fuller, Patrick M.; Pedersen, Nigel P.; Lu, Jun; Scammell, Thomas E.

2010-01-01

129

Photoconductive switch package  

SciTech Connect

A photoconductive switch is formed of a substrate that has a central portion of SiC or other photoconductive material and an outer portion of cvd-diamond or other suitable material surrounding the central portion. Conducting electrodes are formed on opposed sides of the substrate, with the electrodes extending beyond the central portion and the edges of the electrodes lying over the outer portion. Thus any high electric fields produced at the edges of the electrodes lie outside of and do not affect the central portion, which is the active switching element. Light is transmitted through the outer portion to the central portion to actuate the switch.

Ca[rasp, George J

2013-10-22

130

Switching between oral anticoagulants.  

PubMed

Until about 4 years ago, warfarin was the only oral anticoagulant approved in the United States, and switching between oral anticoagulants has become an option since the emergence of the novel oral anticoagulants dabigatran, rivaroxaban, and apixaban. What are the reasons one may switch between the agents and how is this done? Discussed in this article are the 4 agents approved in the United States, their characteristics, reasons one may switch, and methods for conversion. After a thorough search of original trial data and recent expert review articles, we have summarized the most recent recommendations below and briefly discuss upcoming oral anticoagulants that show promise. PMID:25255408

Strasser, Kristen M; Qasem, Abdulraheem; Madhusudhana, Sheshadri

2014-08-01

131

SLOB: a switch with large optical buffers for packet switching  

Microsoft Academic Search

Recently, optical packet switch architectures, composed of devices such as optical switches, fiber delay lines, and passive couplers, have been proposed to overcome the electromagnetic interference (EMI), pinout and interconnection problems that would be encountered in future large electronic switch cores. However, attaining the buffer size (buffer depth) in optical packet switches required in practice is a major problem; in

David K. Hunter; W. David Cornwell; Tim H. Gilfedder; A. Franzen; I. Andonovic

1998-01-01

132

Basics of Safety Switches  

NSDL National Science Digital Library

This course is one of the quickStep series offered by Siemens in Safety Switches. These are FREE on-line industrial knowledge building tutorials. quickSTEPs are a great start for industry novices moving into technical jobs or staff in operational support rolls. They can also be very effectively used as out of class assignments for review or to build fundamental skills. Each course includes: an online tutorial organized as a number of units, lessons with self check quiz questions, a glossary of terms, a self-check final exam with scoring, an extensive downloadable PDF study guide. This course offers: current protection, fuses, enclosures, switch design, switch terminology, safety switches, a final exam, a glossary and a 72 page study guide.

2008-11-25

133

Plasmonic enhanced ultrafast switch.  

SciTech Connect

Ultrafast electronic switches fabricated from defective material have been used for several decades in order to produce picosecond electrical transients and TeraHertz radiation. Due to the ultrashort recombination time in the photoconductor materials used, these switches are inefficient and are ultimately limited by the amount of optical power that can be applied to the switch before self-destruction. The goal of this work is to create ultrafast (sub-picosecond response) photoconductive switches on GaAs that are enhanced through plasmonic coupling structures. Here, the plasmonic coupler primarily plays the role of being a radiation condenser which will cause carriers to be generated adjacent to metallic electrodes where they can more efficiently be collected.

Subramania,Ganapathi Subramanian; Reno, John Louis; Passmore, Brandon Scott; Harris, Tom.; Shaner, Eric Arthur; Barrick, Todd A.

2009-09-01

134

Pneumatic RF MEMS switch using a liquid metal droplet  

NASA Astrophysics Data System (ADS)

We introduce a new design for radio frequency (RF) microelectromechanical systems (MEMS) switch that uses a liquid metal (LM) droplet as a switching component. The switch uses a polymer membrane atop the droplet as a pressure transducer. Initially, a signal passes through a coplanar waveguide (CPW) line (i.e. the switch is on). Pneumatic pressure on the membrane pushes the droplet, thus reducing the gap between the bottom surface of the LM droplet and CPW line; when the gap becomes less than a critical distance, the signal is blocked (i.e. the switch is off). This switch is more stable and has better isolation than do existing RF MEMS switches that use LM droplets. We used a commercial simulation tool (CST Microwave Studio®) to confirm the feasibility of the concept, then fabricated a prototype device that has the same insertion loss as the reference configuration (i.e. a CPW line only). Applying ˜35 kPa pressure to the flexible membrane resulted in switching performances with ˜50 dB isolation at 3 GHz and when the pressure is removed, the switch insertion loss was measured ˜1.5 dB.

Baek, Seungbum; Park, Usung; Choi, In Ho; Kim, Joonwon

2013-05-01

135

Switching power supply filter  

NASA Technical Reports Server (NTRS)

A filter for a switching power supply. The filter includes a common mode inductor with coil configurations allowing differential mode current from a dc source to pass through but attenuating common mode noise from the power supply so that the noise does not reach the dc source. The invention also includes the use of feed through capacitors at the switching power supply input terminals to provide further high-frequency noise attenuation.

Kumar, Prithvi R. (Inventor); Abare, Wayne (Inventor)

1989-01-01

136

uv preilluminated gas switches  

SciTech Connect

We have designed, built, and characterized uv preilluminated gas switches for a trigger circuit and a low inductance discharge circuit. These switches have been incorporated into a 54 x 76 x 150 cm pulser module to produce a 1 Ma output current rising at 5 x 10/sup 12/ amps/sec with 1 ns jitter. Twenty such modules will be used on the Nova Inertial Confinement Fusion Laser System for plasma retropulse shutters.

Bradley, L.P.; Orham, E.L.; Stowers, I.F.; Braucht, J.R.

1980-06-03

137

Optical shutter switching matrix  

NASA Technical Reports Server (NTRS)

The interface switching systems are discussed which are related to those used in the Space Shuttle ground control system, transmission systems, communications systems, and airborne radar electronic countermeasure systems. The main goal is to identify a need that exists throughout the comprehensive information processing and communications disciplines supporting the Space Shuttle and Space Station programs, and introduce one viable approach to satisfy that need. The proposed device, described in NASA patent entitled 'Optical Shutter Switch Matrix', is discussed.

Grove, Charles H.

1991-01-01

138

Cygnus Water Switch Jitter  

SciTech Connect

The Cygnus Dual Beam Radiographic Facility consists of two identical radiographic sources - Cygnus 1 and Cygnus 2. Each source has the following x-ray output: 1-mm diameter spot size, 4 rad at 1 m, 50-ns Full Width Half Max. The diode pulse has the following electrical specifications: 2.25 MV, 60 kA, 60 ns. This Radiographic Facility is located in an underground tunnel test area at the Nevada Test Site (NTS). The sources were developed to produce high-resolution images on subcritical tests which are performed at NTS. Subcritical tests are single-shot, high-value events. For this application, it is desirable to maintain a high level of reproducibility in source output. The major components of the Cygnus machines are: Marx generator, water-filled pulse–forming line (PFL), water-filled coaxial transmission line, three-cell inductive voltage adder, and rod-pinch diode. A primary source of fluctuation in Cygnus shot-to-shot performance is jitter in breakdown of the main PFL switch, which is a “self-break” switch. The PFL switch breakdown time determines the peak PFL charging voltage, which ultimately affects the diode pulse. Therefore, PFL switch jitter contributes to shot-to-shot variation in source endpoint energy and dose. In this paper we will present PFL switch jitter analysis for both Cygnus machines and give the correlation with diode performance. For this analysis the PFL switch on each machine was maintained at a single gap setting which has been used for the majority of shots at NTS. In addition to this analysis, PFL switch performance for different switch gap settings taken recently will be examined. Lastly, implications of source jitter for radiographic diagnosis of subcritical shots will be discussed.

Charles V. Mitton, George D. Corrow, Mark D. Hansen, David J. Henderson, et al.

2008-03-01

139

Critical Critical Systems  

Microsoft Academic Search

I discuss the view of communication networks as self-organised critical systems, the mathematical models that may be needed to describe the emergent properties of such networks, and how certain security hygiene schemes may push a network into a super-critical state, potentially leading to large scale security disasters.

Susan Stepney

2002-01-01

140

PS'2006 -Photonics in Switching Conference Optical Buffering and Switching for Optical Packet Switching  

E-print Network

for future optical communication networking. Optical packet switching is a highly desirable approach; however, but severely limit network performance if used as the sole solution. The architecture for the packet switchPS'2006 - Photonics in Switching Conference Optical Buffering and Switching for Optical Packet

Bowers, John

141

The role of inhibition in task switching: A review  

Microsoft Academic Search

The concept of inhibition plays a major role in cognitive psychology. In the present article, we review the evidence for the\\u000a inhibition of task sets. In the first part, we critically discuss empirical findings of task inhibition from studies that\\u000a applied variants of the task-switching methodology and argue that most of these findings— such as switch cost asymmetries—are\\u000a ambiguous. In

Iring Koch; Miriam Gade; Stefanie Schuch; Andrea M. Philipp

2010-01-01

142

Free-space micromachined optical switches for optical networking  

Microsoft Academic Search

Fiber-optic switches with high port count have emerged as leading candidates for deployment in future optical transport networks, where restoration and provisioning in the optical layer will become increasingly important. This paper reviews the principle and performance of free-space micromachined optical switches (FS-MOS) featuring free-rotating hinged micromirrors. A single-chip FS-MOS that implements the critical function of bridging-essential for restoration in

L. Y. Lin; E. L. Goldstein; R. W. Tkach

1999-01-01

143

Dynamic critical curve of a synthetic antiferromagnet  

NASA Astrophysics Data System (ADS)

In this letter, a dynamic generalization of static critical curves (sCCs) for synthetic antiferromagnet (SAF) structures is presented, analyzing the magnetization switching of SAF elements subjected to pulsed magnetic fields. The dependence of dynamic critical curves (dCCs) on field pulse's shape and length, on damping, and on magnetostatic coupling is investigated. Comparing sCCs, which are currently used for studying the switching in toggle magnetic random access memories, with dCCs, it is shown that a consistent switching can be achieved only under specific conditions that take into account the dynamics of the systems. The study relies on the Landau-Lifshitz-Gilbert equation.

Pham, Huy; Cimpoesu, Dorin; Plamad?, Andrei-Valentin; Stancu, Alexandru; Spinu, Leonard

2009-11-01

144

SWITCH user's manual  

NASA Technical Reports Server (NTRS)

The planning program, SWITCH, and its surrounding changed-goal-replanning program, Runaround, are described. The evolution of SWITCH and Runaround from an earlier planner, DEVISER, is recounted. SWITCH's plan representation, and its process of building a plan by backward chaining with strict chronological backtracking, are described. A guide for writing knowledge base files is provided, as are narrative guides for installing the program, running it, and interacting with it while it is running. Some utility functions are documented. For the sake of completeness, a narrative guide to the experimental discrepancy-replanning feature is provided. Appendices contain knowledge base files for a blocksworld domain, and a DRIBBLE file illustrating the output from, and user interaction with, the program in that domain.

1987-01-01

145

Optical computer switching network  

NASA Technical Reports Server (NTRS)

The design for an optical switching system for minicomputers that uses an optical spatial light modulator such as a Hughes liquid crystal light valve is presented. The switching system is designed to connect 80 minicomputers coupled to the switching system by optical fibers. The system has two major parts: the connection system that connects the data lines by which the computers communicate via a two-dimensional optical matrix array and the control system that controls which computers are connected. The basic system, the matrix-based connecting system, and some of the optical components to be used are described. Finally, the details of the control system are given and illustrated with a discussion of timing.

Clymer, B.; Collins, S. A., Jr.

1985-01-01

146

Switching power supply  

DOEpatents

The invention is a repratable capacitor charging, switching power supply. A ferrite transformer steps up a dc input. The transformer primary is in a full bridge configuration utilizing power MOSFETs as the bridge switches. The transformer secondary is fed into a high voltage, full wave rectifier whose output is connected directly to the energy storage capacitor. The transformer is designed to provide adequate leakage inductance to limit capacitor current. The MOSFETs are switched to the variable frequency from 20 to 50 kHz to charge a capacitor from 0.6 kV. The peak current in a transformer primary and secondary is controlled by increasing the pulse width as the capacitor charges. A digital ripple counter counts pulses and after a preselected desired number is reached an up-counter is clocked.

Mihalka, A.M.

1984-06-05

147

Magnetic switches and circuits  

SciTech Connect

This report outlines the use of saturable inductors as switches in lumped-element, magnetic-pulse compression circuits is discussed and the characteristic use of each is defined. In addition, the geometric constraints and magnetic pulse compression circuits used in short-pulse, low-inductance systems are considered. The scaling of presaturation leakage currents, magnetic energy losses, and switching times with geometrical and material parameters are developed to aid in evaluating magnetic pulse compression systems in a particular application. Finally, a scheme for increasing the couping coefficient in saturable stripline transformers is proposed to enable their use in the short-pulse, high-voltage regime.

Nunnally, W.C.

1982-05-01

148

Improved optical pseudospark switch  

NASA Astrophysics Data System (ADS)

Disclosed is a high-voltage, high-current, multichannel, optically-triggered switch with the potential for improved lifetime of operation. Triggering of the switch is accomplished by ultraviolet illumination of multiple cathode apertures via fiber-optic cables. The trigger optics for each channel, being composed of a fiber-optic cable terminated by some collimating optics, are protected from damaging metalization by enclosing them in an angled metal or dielectric tubes in the cathode back-space. The use of collimating optics at the output of the fiber allows the fiber to be recessed inside the shield tube, providing further protection from discharge by-products.

Grothaus, Michael G.; Bernardes, Jack S.; Stoudt, David C.

1993-05-01

149

Thermionic gas switch  

DOEpatents

A temperature responsive thermionic gas switch having folded electron emitting surfaces. An ionizable gas is located between the emitter and an interior surface of a collector, coaxial with the emitter. In response to the temperature exceeding a predetermined level, sufficient electrons are derived from the emitter to cause the gas in the gap between the emitter and collector to become ionized, whereby a very large increase in current in the gap occurs. Due to the folded emitter surface area of the switch, increasing the "on/off" current ratio and adjusting the "on" current capacity is accomplished.

Hatch, George L. (San Francisco, CA); Brummond, William A. (Livermore, CA); Barrus, Donald M. (San Jose, CA)

1986-01-01

150

Bearingless switched reluctance motor  

NASA Technical Reports Server (NTRS)

A switched reluctance motor has a stator with a first set of poles directed toward levitating a rotor horizontally within the stator. A disc shaped portion of a hybrid rotor is affected by the change in flux relative to the current provided at these levitation poles. A processor senses the position of the rotor and changes the flux to move the rotor toward center of the stator. A second set of poles of the stator are utilized to impart torque upon a second portion of the rotor. These second set of poles are driven in a traditional switched reluctance manner by the processor.

Morrison, Carlos R. (Inventor)

2004-01-01

151

A nanophotonic switching cell  

NASA Astrophysics Data System (ADS)

We present a nanophotonic/nanometric switching cell to operate in the infrared and terahertz frequency range of telecommunications. This switching cell is based on a directional coupler made of two graphene nanoribbons separated in the vertical direction, which are embedded in a hexagonal boron nitride substrate. Theoretical analysis revealed that a graphene based nanophotonics coupler, initially working in the bar state (or cross state), can be brought into the cross state (or bar state), by modifying the graphene sheet chemical potential via the gate voltage. The analytical results are confirmed by the finite element method simulations and numerical analysis scripts.

Wirth L, A.; Sombra, A. S. B.

2014-10-01

152

Polariton Condensate Transistor Switch  

E-print Network

A polariton condensate transistor switch is realized through optical excitation of a microcavity ridge with two beams. The ballistically ejected polaritons from a condensate formed at the source are gated using the 20 times weaker second beam to switch on and off the flux of polaritons. In the absence of the gate beam the small built-in detuning creates potential landscape in which ejected polaritons are channelled toward the end of the ridge where they condense. The low loss photon-like propagation combined with strong nonlinearities associated with their excitonic component makes polariton based transistors particularly attractive for the implementation of all-optical integrated circuits.

Gao, T; Liew, T C H; Tsintzos, S I; Stavrinidis, G; Deligeorgis, G; Hatzopoulos, Z; Savvidis, P G

2012-01-01

153

Main electrical switch banks, plant switch house, looking to the ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Main electrical switch banks, plant switch house, looking to the North - Bureau of Mines Metallurgical Research Laboratory, Original Building, Date Street north of U.S. Highway 93, Boulder City, Clark County, NV

154

41. INTERIOR VIEW, GREEN SWITCH TOWER, COS COB, SHOWING SWITCH ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

41. INTERIOR VIEW, GREEN SWITCH TOWER, COS COB, SHOWING SWITCH LEVER ASSEMBLAGE AND DISPLAY BOARD - New York, New Haven & Hartford Railroad, Automatic Signalization System, Long Island Sound shoreline between Stamford & New Haven, Stamford, Fairfield County, CT

155

35. END VIEW, INTERIOR, SHOWING SWITCHING LEVERS, BERK SWITCH TOWER, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

35. END VIEW, INTERIOR, SHOWING SWITCHING LEVERS, BERK SWITCH TOWER, SOUTH NORWALK - New York, New Haven & Hartford Railroad, Automatic Signalization System, Long Island Sound shoreline between Stamford & New Haven, Stamford, Fairfield County, CT

156

36. INTERIOR VIEW, BERK SWITCH TOWER, SOUTH NORWALK, SHOWING SWITCHING ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

36. INTERIOR VIEW, BERK SWITCH TOWER, SOUTH NORWALK, SHOWING SWITCHING LEVERS FROM OPERATOR'S POSITION - New York, New Haven & Hartford Railroad, Automatic Signalization System, Long Island Sound shoreline between Stamford & New Haven, Stamford, Fairfield County, CT

157

Modeling Task Switching Without Switching Tasks: A Short-Term Priming Account of Explicitly Cued Performance  

E-print Network

Modeling Task Switching Without Switching Tasks: A Short-Term Priming Account of Explicitly Cued Performance Darryl W. Schneider and Gordon D. Logan Vanderbilt University Switch costs in task switching--including putative switch costs-- without switching tasks. Keywords: task switching, switch cost, priming, compound

Logan, Gordon D.

158

Switching of ferroelectrics without domains.  

PubMed

A discussion of switching in polyvinyl difluoride copolymers is given (see L. Zhang, EPL 2010, 91, 47001) in terms of the general history of ferroelectric switching with and without domain wall participation. PMID:21170923

Scott, James F

2010-12-01

159

Kiowa Creek Switching Station  

SciTech Connect

The Western Area Power Administration (Western) proposes to construct, operate, and maintain a new Kiowa Creek Switching Station near Orchard in Morgan County, Colorado. Kiowa Creek Switching Station would consist of a fenced area of approximately 300 by 300 feet and contain various electrical equipment typical for a switching station. As part of this new construction, approximately one mile of an existing 115-kilovolt (kV) transmission line will be removed and replaced with a double circuit overhead line. The project will also include a short (one-third mile) realignment of an existing line to permit connection with the new switching station. In accordance with the Council on Environmental Quality (CEQ) regulations for implementing the procedural provisions of the National Environmental Policy Act of 1969 (NEPA), 40 CFR Parts 1500--1508, the Department of Energy (DOE) has determined that an environmental impact statement (EIS) is not required for the proposed project. This determination is based on the information contained in this environmental assessment (EA) prepared by Western. The EA identifies and evaluates the environmental and socioeconomic effects of the proposed action, and concludes that the advance impacts on the human environment resulting from the proposed project would not be significant. 8 refs., 3 figs., 1 tab.

Not Available

1990-03-01

160

High Speed Packet Switching.  

National Technical Information Service (NTIS)

This document constitutes the final report prepared by Proteon, Inc. of Westborough, Massachusetts under contract NAS 5-30629 entitled High-Speed Packet Switching (SBIR 87-1, Phase 2) prepared for NASA-Greenbelt, Maryland. The primary goal of this researc...

1991-01-01

161

Multipath star switch controller  

NASA Technical Reports Server (NTRS)

Device concept permits parallel computers to scan several commonnetwork-connected data stations at maximum rate. Sequencers leap-frog to bypass ports already being serviced by another computer. Two-path system for 16-port star switch controller is cost effective if added bandwidth or increased reliability is desired. Triple-path system would be cost effective for 32-port controller.

Anderson, T. O.

1980-01-01

162

Tag switching architecture overview  

Microsoft Academic Search

Tag switching is a way to combine the label-swapping forwarding paradigm with network-layer routing with particular application to the Internet. This has several advantages. Tags can have a wide spectrum of forwarding granularities, so at one end of the spectrum a tag could be associated with a group of destinations, while at the other end, a tag could be associated

YAKOV REKHTER; BRUCE DAVIE; ERIC ROSEN; GEORGE SWALLOW; DINO FARINACCI; DAVE KATZ

1997-01-01

163

Molecular Rotors as Switches  

PubMed Central

The use of a functional molecular unit acting as a state variable provides an attractive alternative for the next generations of nanoscale electronics. It may help overcome the limits of conventional MOSFETd due to their potential scalability, low-cost, low variability, and highly integratable characteristics as well as the capability to exploit bottom-up self-assembly processes. This bottom-up construction and the operation of nanoscale machines/devices, in which the molecular motion can be controlled to perform functions, have been studied for their functionalities. Being triggered by external stimuli such as light, electricity or chemical reagents, these devices have shown various functions including those of diodes, rectifiers, memories, resonant tunnel junctions and single settable molecular switches that can be electronically configured for logic gates. Molecule-specific electronic switching has also been reported for several of these device structures, including nanopores containing oligo(phenylene ethynylene) monolayers, and planar junctions incorporating rotaxane and catenane monolayers for the construction and operation of complex molecular machines. A specific electrically driven surface mounted molecular rotor is described in detail in this review. The rotor is comprised of a monolayer of redox-active ligated copper compounds sandwiched between a gold electrode and a highly-doped P+ Si. This electrically driven sandwich-type monolayer molecular rotor device showed an on/off ratio of approximately 104, a read window of about 2.5 V, and a retention time of greater than 104 s. The rotation speed of this type of molecular rotor has been reported to be in the picosecond timescale, which provides a potential of high switching speed applications. Current-voltage spectroscopy (I-V) revealed a temperature-dependent negative differential resistance (NDR) associated with the device. The analysis of the device I–V characteristics suggests the source of the observed switching effects to be the result of the redox-induced ligand rotation around the copper metal center and this attribution of switching is consistent with the observed temperature dependence of the switching behavior as well as the proposed energy diagram of the device. The observed resistance switching shows the potential for future non-volatile memories and logic devices applications. This review will discuss the progress and provide a perspective of molecular motion for nanoelectronics and other applications.

Xue, Mei; Wang, Kang L.

2012-01-01

164

CRITICAL NOTICES 227 Critical Notices  

E-print Network

CRITICAL NOTICES 227 Critical Notices Critical Scientific Realism. ILKKA NIINILUOTO. Oxford: Oxford, there remain problems for realists to tackle if they are to demonstrate that the position is coherent. Critical

Chakravartty, Anjan

165

Transparent electrode for optical switch  

DOEpatents

The invention relates generally to optical switches and techniques for applying a voltage to an electro-optical crystal, and more particularly, to transparent electodes for an optical switch. System architectures for very large inertial confinement fusion (ICF) lasers require active optical elements with apertures on the order of one meter. Large aperture optical switches are needed for isolation of stages, switch-out from regenerative amplifier cavities and protection from target retroreflections.

Goldhar, J.; Henesian, M.A.

1984-10-19

166

Task set switching in schizophrenia  

Microsoft Academic Search

The authors used a task-switching paradigm to investigate set shifting ability in schizophre- nia. This paradigm included 2 choice reaction time (RT) tasks: up--down and right-left. Switching tasks were associated with costs (i.e., longer RT in task-switch trials than in task-repetition trials); patients responded more slowly than controls and suffered greater switching costs, were as efficient as controls in engaging

Nachshon Meiran; Joseph Levine; Naama Meiran; Avishai Henik

2000-01-01

167

Easily-wired toggle switch  

NASA Technical Reports Server (NTRS)

Crimp-type connectors reduce assembly and disassembly time. With design, no switch preparation is necessary and socket contracts are crimped to wires inserted in module attached to back of toggle switch engaging pins inside module to make electrical connections. Wires are easily removed with standard detachment tool. Design can accommodate wires of any gage and as many terminals can be placed on switch as wire gage and switch dimensions will allow.

Dean, W. T.; Stringer, E. J.

1979-01-01

168

Language Switching and Language Competition  

ERIC Educational Resources Information Center

This study examined the asymmetrical language switching cost in a word reading task (Experiment 1) and in a categorization task (Experiment 2 and 3). In Experiment 1, Spanish-English bilinguals named words in first language (L1) and second language (L2) in a switching paradigm. They were slower to switch from their weaker L2 to their more dominant…

Macizo, Pedro; Bajo, Teresa; Paolieri, Daniela

2012-01-01

169

Organic Materials For Optical Switching  

NASA Technical Reports Server (NTRS)

Equations predict properties of candidate materials. Report presents results of theoretical study of nonlinear optical properties of organic materials. Such materials used in optical switching devices for computers and telecommunications, replacing electronic switches. Optical switching potentially offers extremely high information throughout in compact hardware.

Cardelino, Beatriz H.

1993-01-01

170

High-power microstrip switch  

NASA Technical Reports Server (NTRS)

Switch, which uses only two p-i-n diodes on microstrip substrate, has been developed for application in spacecraft radio systems. Switch features improved power drain, weight, volume, magnetic cleanliness, and reliability, over currently-used circulator and electromechanical switches.

Choi, S. D.

1974-01-01

171

Research Article Inhibition Versus Switching  

E-print Network

information. We used a task-switching paradigm that can distinguish between these two processes. Two rumination are associated with difficulties in switching to a new task set, but not with inhibitionResearch Article Inhibition Versus Switching Deficits in Different Forms of Rumination Anson J

Banich, Marie T.

172

Component Processes in Task Switching.  

ERIC Educational Resources Information Center

Studied task switching in 4 experiments involving 111 Israeli undergraduates. Results show the preparation for a task switch is not a by-product of general preparation by phasic alertness or predicting target onset and establish reconfiguration as a separate preparatory process. Suggests that there are at least three components of task switching

Meiran, Nachshon; Chorev, Ziv; Sapir, Ayelet

2000-01-01

173

Task Switching: A PDP Model  

Microsoft Academic Search

When subjects switch between a pair of stimulus–response tasks, reaction time is slower on trial N if a different task was performed on trial N ? 1. We present a parallel distributed processing (PDP) model that simulates this effect when subjects switch between word reading and color naming in response to Stroop stimuli. Reaction time on “switch trials” can be

Sam J. Gilbert; Tim Shallice

2002-01-01

174

High speed switching in gases  

SciTech Connect

A fast, efficient and reliable switch is the basic ingredient of a pulse power accelerator. Two switches have been proposed so far: the solid state switch, and the vacuum photodiode switch. The solid state version has been tested to some extent, albeit at low (few kilovolts) level, with risetime around 10 ps in the radial line transformer configuration. The vacuum photodiode is being investigated by Fisher and Rao at Brookhaven National Laboratory. Common to both switches is the need of a short laser pulse; near infrared for the solid state switch, and ultraviolet for the vacuum photodiode switch. Another common feature is the poor energy gain of these switches: the gain being the ratio between the electrical energy switched and the laser energy needed to drive the switch. For the solid state switch, calculations and experimental data show that the energy gain cannot exceed a value between 5 and 10. For the vacuum photodiode, the situation is somewhat similar, unless very high quantum efficiency, rugged photocathodes can be found. A closing switch also can be used to produce short pulses of rf at frequencies related to its closing time, using a well-known device called the frozen wave generator. For a risetime of the order of 30 ps, one could produce several Gigawatts of rf at Xband at very low cost. 12 refs., 12 figs.

Cassell, R.E.; Villa, F.

1989-02-01

175

Task Switching: A PDP Model  

ERIC Educational Resources Information Center

When subjects switch between a pair of stimulus-response tasks, reaction time is slower on trial N if a different task was performed on trial N--1. We present a parallel distributed processing (PDP) model that simulates this effect when subjects switch between word reading and color naming in response to Stroop stimuli. Reaction time on "switch

Gilbert, Sam J.; Shallice, Tim

2002-01-01

176

Illuminated push-button switch  

NASA Technical Reports Server (NTRS)

An illuminated push-button switch is described. It is characterized by the fact that is consists of a switch group, an operator button opening and closing the switch group, and a light-emitting element which illuminates the face of the operator button.

Iwagiri, T.

1983-01-01

177

Advances in integrated photonic circuits for packet-switched interconnection  

NASA Astrophysics Data System (ADS)

Sustained increases in capacity and connectivity are needed to overcome congestion in a range of broadband communication network nodes. Packet routing and switching in the electronic domain are leading to unsustainable energy- and bandwidth-densities, motivating research into hybrid solutions: optical switching engines are introduced for massive-bandwidth data transport while the electronic domain is clocked at more modest GHz rates to manage routing. Commercially-deployed optical switching engines using MEMS technologies are unwieldy and too slow to reconfigure for future packet-based networking. Optoelectronic packet-compliant switch technologies have been demonstrated as laboratory prototypes, but they have so far mostly used discretely pigtailed components, which are impractical for control plane development and product assembly. Integrated photonics has long held the promise of reduced hardware complexity and may be the critical step towards packet-compliant optical switching engines. Recently a number of laboratories world-wide have prototyped optical switching circuits using monolithic integration technology with up to several hundreds of integrated optical components per chip. Our own work has focused on multi-input to multi-output switching matrices. Recently we have demonstrated 8×8×8? space and wavelength selective switches using gated cyclic routers and 16×16 broadband switching chips using monolithic multi-stage networks. We now operate these advanced circuits with custom control planes implemented with FPGAs to explore real time packet routing in multi-wavelength, multi-port test-beds. We review our contributions in the context of state of the art photonic integrated circuit technology and packet optical switching hardware demonstrations.

Williams, Kevin A.; Stabile, Ripalta

2014-03-01

178

The structure of Plasmodium falciparum serine hydroxymethyltransferase reveals a novel redox switch that regulates its activities  

PubMed Central

Plasmodium falciparum serine hydroxymethyltransferase (PfSHMT), an enzyme in the dTMP synthesis cycle, is an antimalarial target because inhibition of its expression or function has been shown to be lethal to the parasite. As the wild-type enzyme could not be crystallized, protein engineering of residues on the surface was carried out. The surface-engineered mutant PfSHMT-F292E was successfully crystallized and its structure was determined at 3?Å resolution. The PfSHMT-F292E structure is a good representation of PfSHMT as this variant revealed biochemical properties similar to those of the wild type. Although the overall structure of PfSHMT is similar to those of other SHMTs, unique features including the presence of two loops and a distinctive cysteine pair formed by Cys125 and Cys364 in the tetrahydrofolate (THF) substrate binding pocket were identified. These structural characteristics have never been reported in other SHMTs. Biochemical characterization and mutation analysis of these two residues confirm that they act as a disulfide/sulfhydryl switch to regulate the THF-dependent catalytic function of the enzyme. This redox switch is not present in the human enzyme, in which the cysteine pair is absent. The data reported here can be further exploited as a new strategy to specifically disrupt the activity of the parasite enzyme without interfering with the function of the human enzyme. PMID:24914963

Chitnumsub, Penchit; Ittarat, Wanwipa; Jaruwat, Aritsara; Noytanom, Krittikar; Amornwatcharapong, Watcharee; Pornthanakasem, Wichai; Chaiyen, Pimchai; Yuthavong, Yongyuth; Leartsakulpanich, Ubolsree

2014-01-01

179

Fault-tolerant onboard digital information switching and routing for communications satellites  

NASA Technical Reports Server (NTRS)

The NASA Lewis Research Center is developing an information-switching processor for future meshed very-small-aperture terminal (VSAT) communications satellites. The information-switching processor will switch and route baseband user data onboard the VSAT satellite to connect thousands of Earth terminals. Fault tolerance is a critical issue in developing information-switching processor circuitry that will provide and maintain reliable communications services. In parallel with the conceptual development of the meshed VSAT satellite network architecture, NASA designed and built a simple test bed for developing and demonstrating baseband switch architectures and fault-tolerance techniques. The meshed VSAT architecture and the switching demonstration test bed are described, and the initial switching architecture and the fault-tolerance techniques that were developed and tested are discussed.

Shalkhauser, Mary JO; Quintana, Jorge A.; Soni, Nitin J.; Kim, Heechul

1993-01-01

180

Experimental parametric study of the parasitic inductance influence on MOSFET switching characteristics  

Microsoft Academic Search

This paper presents an experimental parametric study of the parasitic inductance influence on MOSFET switching waveforms. The three most critical stray inductances, namely the gate-loop, switching-loop, and common-source inductances have all been studied and compared in terms of their effect on waveform ringing, switching loss, device stress, and electromagnetic interference. Based on the results obtained, a guideline has been established

Zheng Chen; Dushan Boroyevich; Rolando Burgos

2010-01-01

181

Optical fiber switch  

DOEpatents

Optical fiber switches operated by electrical activation of at least one laser light modulator through which laser light is directed into at least one polarizer are used for the sequential transport of laser light from a single laser into a plurality of optical fibers. In one embodiment of the invention, laser light from a single excitation laser is sequentially transported to a plurality of optical fibers which in turn transport the laser light to separate individual remotely located laser fuel ignitors. The invention can be operated electro-optically with no need for any mechanical or moving parts, or, alternatively, can be operated electro-mechanically. The invention can be used to switch either pulsed or continuous wave laser light.

Early, James W. (Los Alamos, NM); Lester, Charles S. (San Juan Pueblo, NM)

2002-01-01

182

Plasma opening switch  

DOEpatents

A command triggered plasma opening switch assembly using an amplification stage. The assembly surrounds a coaxial transmission line and has a main plasma opening switch (POS) close to the load and a trigger POS upstream from the main POS. The trigger POS establishes two different current pathways through the assembly depended on whether it has received a trigger current pulse. The initial pathway has both POS's with plasma between their anodes and cathodes to form a short across the transmission line and isolating the load. The final current pathway is formed when the trigger POS receives a trigger current pulse which energizes its fast coil to push the conductive plasma out from between its anode and cathode, allowing the main transmission line current to pass to the fast coil of the main POS, thus pushing its plasma out the way so as to establish a direct current pathway to the load.

Savage, Mark E. (Albuquerque, NM); Mendel, Jr., Clifford W. (Albuquerque, NM)

2001-01-01

183

Switching Power Supplies  

NSDL National Science Digital Library

Created by Work-Ready Electronics, a project of the Advanced Technological Education program, this module walks visitors through the basics of switching power supplies. The content of the site is divided into four areas: SMPS Basics and Switching Regulators; DC-DC Converters: Charge Pumps, Forwards Converters and Flyback Converters; Inverters, UPS and Hysteresis Curve, and SMPS: Advantages, Disadvantages and Troubleshooting. There is a quiz for each area in the Knowledge Probe area, and the Learning Resources section contains five activities to help cement student understanding. There are also further resources - both print and Web based - for more information and two Questors, a Flash trivia game. The Notebook function allows visitors to take notes and review them at any time. This is an excellent resource students and educators in electronics technician programs.

2008-09-05

184

The Acetate Switch  

PubMed Central

To succeed, many cells must alternate between life-styles that permit rapid growth in the presence of abundant nutrients and ones that enhance survival in the absence of those nutrients. One such change in life-style, the “acetate switch,” occurs as cells deplete their environment of acetate-producing carbon sources and begin to rely on their ability to scavenge for acetate. This review explains why, when, and how cells excrete or dissimilate acetate. The central components of the “switch” (phosphotransacetylase [PTA], acetate kinase [ACK], and AMP-forming acetyl coenzyme A synthetase [AMP-ACS]) and the behavior of cells that lack these components are introduced. Acetyl phosphate (acetyl?P), the high-energy intermediate of acetate dissimilation, is discussed, and conditions that influence its intracellular concentration are described. Evidence is provided that acetyl?P influences cellular processes from organelle biogenesis to cell cycle regulation and from biofilm development to pathogenesis. The merits of each mechanism proposed to explain the interaction of acetyl?P with two-component signal transduction pathways are addressed. A short list of enzymes that generate acetyl?P by PTA-ACKA-independent mechanisms is introduced and discussed briefly. Attention is then directed to the mechanisms used by cells to “flip the switch,” the induction and activation of the acetate-scavenging AMP-ACS. First, evidence is presented that nucleoid proteins orchestrate a progression of distinct nucleoprotein complexes to ensure proper transcription of its gene. Next, the way in which cells regulate AMP-ACS activity through reversible acetylation is described. Finally, the “acetate switch” as it exists in selected eubacteria, archaea, and eukaryotes, including humans, is described. PMID:15755952

Wolfe, Alan J.

2005-01-01

185

Automatic switching matrix  

DOEpatents

An automatic switching matrix that includes an apertured matrix board containing a matrix of wires that can be interconnected at each aperture. Each aperture has associated therewith a conductive pin which, when fully inserted into the associated aperture, effects electrical connection between the wires within that particular aperture. Means is provided for automatically inserting the pins in a determined pattern and for removing all the pins to permit other interconnecting patterns.

Schlecht, Martin F. (Cambridge, MA); Kassakian, John G. (Newton, MA); Caloggero, Anthony J. (Lynn, MA); Rhodes, Bruce (Dorchester, MA); Otten, David (Newton, MA); Rasmussen, Neil (Sudbury, MA)

1982-01-01

186

Composite Material Switches  

NASA Technical Reports Server (NTRS)

A device to protect electronic circuitry from high voltage transients is constructed from a relatively thin piece of conductive composite sandwiched between two conductors so that conduction is through the thickness of the composite piece. The device is based on the discovery that conduction through conductive composite materials in this configuration switches to a high resistance mode when exposed to voltages above a threshold voltage.

Javadi, Hamid (Inventor)

2001-01-01

187

Composite Material Switches  

NASA Technical Reports Server (NTRS)

A device to protect electronic circuitry from high voltage transients is constructed from a relatively thin piece of conductive composite sandwiched between two conductors so that conduction is through the thickness of the composite piece. The device is based on the discovery that conduction through conductive composite materials in this configuration switches to a high resistance mode when exposed to voltages above a threshold voltage.

Javadi, Hamid (Inventor)

2002-01-01

188

CREE: Making the Switch  

ScienceCinema

CREE, with the help of ARPA-E funding, has developed a Silicon Carbide (SIC) transistor which can be used to create solid state transformers capable of meeting the unique needs of the emerging smart grid. SIC transistors are different from common silicon computer chips in that they handle grid scale voltages with ease and their high frequency switching is well suited to the intermittent nature of renewable energy generation.

Grider, David; Palmer, John

2014-04-09

189

Optical switch fabric design for gigabit switching router  

NASA Astrophysics Data System (ADS)

One of the key issues of high performance IP Gigabit Switching Router (GSR) design is about switching fabrics. In the traditional bus-based router architectures, the data transfer rate of copper backplanes will soon reach the speed limit because of connector reflections and crosstalk. An alternative optical switching fabric technology is necessary in order to satisfy the demand for high switching bandwidth. In this paper we firstly present a novel all-optical broadcasting switch fabric design scheme based on broadcasting bus architecture. In this section we also illustrate the advantages and disadvantages of this kind of architecture and demonstrate that this kind of switching fabric architecture have no interior block as well as none I/O block. Second, we discuss such implementation scheme of all-optical broadcasting switch fabric architecture as queuing, scheduling and multicasting. Finally, we get a conclusion that all-optical broadcasting switch fabric is one of the cost-effective solutions to design high-speed, scalable and simple switch fabrics compared with those complicated electric crossbar switch fabrics in GSR design.

Wei, Wei; Zeng, QingJi

2001-10-01

190

Ultrafast gas switching experiments  

NASA Astrophysics Data System (ADS)

Recent experiments which studied the physics of ultrafast gas breakdown under the extreme overvoltages which occur when a high pressure gas switch is pulse charged to hundreds of kV in 1 ns or less are described. The highly overvolted peaking gaps produce powerful electromagnetic pulses with risetimes less than 100 ps which can be used for ultrawideband radar systems, particle accelerators, laser drivers, bioelectromagnetic studies, electromagnetic effects testing, and for basic studies of gas breakdown physics. Pulses with 50 to 100 ps risetimes to peak levels of 75 to 160 kV at pulse repetition frequencies (PRF) to 1 kHz were produced and accurately measured. A unique gas switch was developed to hold off hundreds of kV with parasitic inductance less than 1 nH. An advanced diagnostic system using Fourier compensation was developed to measure single-shot risetimes below 35 ps. The complete apparatus is described and waveforms are presented. The measured data are compared with a theoretical model which predicts key features including dependence on gas species and pressure. This technology was applied to practical systems driving ultrawideband radiating antennas and bounded wave simulators. A thyristor/pulse transformer based system using a highly overvolted cable switch was developed. This pulser driving a Sandia-designed TEM cell, provides an ultra wideband impulse with less than 200 ps risetime to the test object at a PRF greater than 1 kHz at grater tha n 100 kV/m E field.

Frost, C. A.; Martin, T. H.; Patterson, P. E.; Rinehart, L. F.; Rohwein, G. J.; Roose, L. D.; Aurand, J. F.; Buttram, M. T.

1993-06-01

191

Cygnus Diverter Switch Analysis  

SciTech Connect

The Cygnus Dual Beam Radiographic Facility consists of two 2.25-MV, 60-kA, 50-ns x-ray sources fielded in an underground laboratory at the Nevada Test Site. The tests performed in this laboratory involve study of the dynamic properties of plutonium and are called subcritical experiments. From end-to-end, the Cygnus machines utilize the following components: Marx generator, water-filled pulse-forming line (PFL), waterfilled coaxial transmission line (WTL), 3-cell inductive voltage adder (IVA), and rod-pinch diode. The upstream WTL interface to the PFL is via a radial insulator with coaxial geometry. The downstream WTL terminates in a manifold where the center conductor splits into three lines which individually connect to each of the IVA cell inputs. There is an impedance mismatch at this juncture. It is a concern that a reflected pulse due to anomalous behavior in the IVA or diode might initiate breakdown upon arrival at the upstream PFL/WTL insulator. Therefore near the beginning of the WTL a radial diverter switch is installed to protect the insulator from over voltage and breakdown. The diverter has adjustable gap spacing, and an in-line aqueous-solution (sodium thiosulfate) resistor array for energy dissipation. There are capacitive voltage probes at both ends of the WTL and on the diverter switch. These voltage signals will be analyzed to determine diverter performance. Using this analysis the usefulness of the diverter switch will be evaluated.

G. Corrow, M. Hansen, D. Henderson, C. Mitton et al.

2008-02-01

192

Effect of excess dietary iron as ferrous sulfate and excess dietary ascorbic acid on liver zinc, copper and sulfhydryl groups and the ovary  

SciTech Connect

Female guinea pigs of the NIH 13/N strain, weighing between 475 and 512 g, were fed diets supplemented with 50 to 2500 mg of iron per kg of diet as ferrous sulfate and 0.2 to 8.0 g of ascorbic acid per kg of diet. A significant effect was observed on tissue copper and zinc, ovary weight and liver protein sulfhydryl groups. The mean ovary weight for guinea pigs fed 2500 mg of iron was significantly less than that of animals fed 50 mg of iron, 0.045 +/- 0.012 g and 0.061 +/- 0.009 g, respectively. Liver zinc content of animals fed 2500 mg of iron and 200 mg of ascorbic acid per kg of diet was significantly less than that of animals fed 50 mg of iron and 200 mg of ascorbic acid, 16.3 +/- 3.3 ..mu..g and 19.6 +/- 1.6 ..mu..g, respectively. There was no difference in liver copper due to dietary iron, but when dietary ascorbic acid was increased to 8 g per kg of diet, there was a significant decrease (from 22.8 +/- 8.1 ..mu..g to 10.5 +/- 4.8 ..mu..g) in liver copper. Excess dietary ascorbic acid decreased ovarian zinc significantly when increased to 8 g per kg of diet, 2929 +/- 919 ..mu..g vs 1661 +/- 471 ..mu..g, respectively, when compared to the control group.

Edwards, C.H.; Adkins, J.S.; Harrison, B.

1986-03-05

193

Anti-ulcerogenic mechanisms of the sesquiterpene lactone onopordopicrin-enriched fraction from Arctium lappa L. (Asteraceae): role of somatostatin, gastrin, and endogenous sulfhydryls and nitric oxide.  

PubMed

Arctium lappa L. has been used in folk medicine as a diuretic, depurative, and digestive stimulant and in dermatological conditions. The mechanisms involved in the anti-ulcerogenic activity of the sesquiterpene onopordopicrin (ONP)-enriched fraction (termed the ONP fraction), obtained from A. lappa leaves, were studied. The gastroprotective mechanism of the ONP fraction was evaluated in experimental in vivo models in rodents, mimicking this disease in humans. ONP fraction (50?mg/kg, p.o.) significantly inhibited the mucosal injury induced by ethanol/HCl solution (75%), indomethacin/bethanecol (68.9%), and stress (58.3%). When the ONP fraction was investigated in pylorus ligature, it did not induce alteration in the gastric volume but did modify the pH and total acid concentration of gastric juice. ONP fraction significantly increased serum somatostatin levels (82.1±4.1 vs. control group 12.7±4?pmol/L) and decreased serum gastrin levels (62.6±6.04 vs. control group 361.5±8.2??U/mL). Mucus production was not significantly altered by the ONP fraction. Gastroprotection by the ONP fraction was completely inhibited by N-ethylmaleimide treatment and did not modify the effect in the animals pretreated with l-N(G)-nitroarginine methyl ester. These results suggest an antisecretory mechanism involved with the antiulcerogenic effect of the ONP fraction. However, only endogenous sulfhydryls play an important role in gastroprotection of the ONP fraction. PMID:22191571

de Almeida, Ana Beatriz Albino; Luiz-Ferreira, Anderson; Cola, Maíra; Di Pietro Magri, Luciana; Batista, Leonia Maria; de Paiva, Joseilson Alves; Trigo, José Roberto; Souza-Brito, Alba R M

2012-04-01

194

The effect of sulfhydryl blocking agents on the uptake of L-carnitine in an established human cell line (CCL 27).  

PubMed

The effect of sulfhydryl blocking agents on the active transport of L-carnitine into cells from an established cell line from human heart was studied. N-ethylmaleimide (MalNEt), 5,5-dithiobis-(2-nitrobenzoic acid) (Nbs2), parachloromercuribenzoate (ClHgBzO-) and cystamin all reduced the uptake of L-carnitine considerably. This was not due to a general membrane injury as judged by the trypan blue dye exclusion test. The inhibition caused by N-ethylmaleimide was irreversible, while that of Nbs2, ClHgBzO- and cystamin could be reversed by dithiothreitol. Excess L-carnitine in the medium exerted a small protective effect against the inhibition of Nbs2, but had no effect against the inhibition of the other agents. Neither could ClHgBzO- protect the uptake mechanism against the irreversible inhibition of N-ethylmaleimide. We conclude that the observations reflect the existence of a multitude of different SH-groups, and that some of these are essential for the cellular uptake of L-carnitine. PMID:7313503

Kjernes, U; Mølstad, P

1981-04-01

195

High-performance multi-queue buffers for VLSI communications switches  

Microsoft Academic Search

Small nxn switches are key components of multistage interconnection networks used in multiprocessors as well as in the communication coprocessors used in multicomputers. The design of the internal buffers in these switches is of critical importance for achieving high throughput low latency communication. We discuss several buffer structures and compare them in terms of implementation complexity and their ability to

Yuval Tamir; Gregory L. Frazier

1988-01-01

196

Operator Performance in Long Duration Control Operations: Switching from Low to High Task Load  

E-print Network

Operator Performance in Long Duration Control Operations: Switching from Low to High Task Load the critical switch to high task load will also affect the operator's ability to respond to the events properly, Cambridge, MA 2 Delft University of Technology, Delft, The Netherlands Long duration, low task load

Cummings, Mary "Missy"

197

Components of task switching: a closer look at task switching and cue switching.  

PubMed

Research using the diffusion model to decompose task-switching effects has contributed to a better understanding of the processes underlying the observed effect in the explicit task cueing paradigm: Previous findings could be reconciled with multiple component models of task switching or with an account on compound-cue retrieval/repetition priming. In the present study, we used two cues for each task in order to decompose task-switch and cue-switch effects. Response time data support previous findings that comparable parts of the switching effect can be attributed to cue-switching and task-switching. A diffusion model analysis of the data confirmed that non-decision time is increased and drift rates are decreased in unpredicted task-switches. Importantly, it was shown that non-decision time was selectively increased in task-switching trials but not in cue-switching trials. Results of the present study specifically support the notion of additional processes in task-switches and can be reconciled with broader multiple component accounts. PMID:25004102

Schmitz, Florian; Voss, Andreas

2014-09-01

198

Photoconductive semiconductor switches: Laser Q-switch trigger and switch-trigger laser integration  

SciTech Connect

This report provides a summary of the Pulser In a Chip 9000-Discretionary LDRD. The program began in January of 1997 and concluded in September of 1997. The over-arching goal of this LDRD is to study whether laser diode triggered photoconductive semiconductor switches (PCSS) can be used to activate electro-optic devices such as Q-switches and Pockels cells and to study possible laser diode/switch integration. The PCSS switches we used were high gain GaAs switches because they can be triggered with small amounts of laser light. The specific goals of the LDRD were to demonstrate: (1) that small laser diode arrays that are potential candidates for laser-switch integration will indeed trigger the PCSS switch, and (2) that high gain GaAs switches can be used to trigger optical Q-switches in lasers such as the lasers to be used in the X-1 Advanced Radiation Source and the laser used for direct optical initiation (DOI) of explosives. The technology developed with this LDRD is now the prime candidate for triggering the Q switch in the multiple lasers in the laser trigger system of the X-1 Advanced Radiation Source and may be utilized in other accelerators. As part of the LDRD we developed a commercial supplier. To study laser/switch integration we tested triggering the high gain GaAs switches with: edge emitting laser diodes, vertical cavity surface emitting lasers (VCSELs), and transverse junction stripe (TJS) lasers. The first two types of lasers (edge emitting and VCSELs) did activate the PCSS but are harder to integrate with the PCSS for a compact package. The US lasers, while easier to integrate with the switch, did not trigger the PCSS at the US laser power levels we used. The PCSS was used to activate the Q-switch of the compact laser to be used in the X-1 Advanced Radiation Source.

Loubriel, G.M.; Mar, A.; Hamil, R.A.; Zutavern, F.J.; Helgeson, W.D.

1997-12-01

199

Structural Determinants for Naturally Evolving H5N1 Hemagglutinin to Switch Its Receptor Specificity  

E-print Network

Of the factors governing human-to-human transmission of the highly pathogenic avian-adapted H5N1 virus, the most critical is the acquisition of mutations on the viral hemagglutinin (HA) to “quantitatively switch” its binding ...

Tharakaraman, Kannan

200

On fault tolerance increase of switched reluctance machines  

Microsoft Academic Search

The switched reluctance machine (SRM) is ideal for safety critical applications (aerospace, automotive, defense, medical, etc.) where it is desirable that the electrical drive system to be fault tolerant. The phase independence characteristics of the SRM enable it to operate (at lower power and higher torque ripples) also under partial phase failure conditions. Its reliability can be improved during its

Loránd SZABÓ; Mircea RUBA

2009-01-01

201

Quality of Service in Asynchronous Bufferless Optical Packet Switched Networks  

Microsoft Academic Search

Optical Packet Switching (OPS) is a promising technology for future core networks due to the ability to handle bursty traffic, adaptability to changes in the network infrastructure and good network utilization. In order to provide sufficient Quality of Service (QoS) to the emerging range of real-time and critical business applications, service differentiation should be present in future OPS. This paper

Harald Øverby; Norvald Stol

2004-01-01

202

Composite Thermal Switch  

NASA Technical Reports Server (NTRS)

Lithium primary and lithium ion secondary batteries provide high specific energy and energy density. The use of these batteries also helps to reduce launch weight. Both primary and secondary cells can be packaged as high-rate cells, which can present a threat to crew and equipment in the event of external or internal short circuits. Overheating of the cell interior from high current flows induced by short circuits can result in exothermic reactions in lithium primary cells and fully charged lithium ion secondary cells. Venting of the cell case, ejection of cell components, and fire have been reported in both types of cells, resulting from abuse, cell imperfections, or faulty electronic control design. A switch has been developed that consists of a thin layer of composite material made from nanoscale particles of nickel and Teflon that conducts electrons at room temperature and switches to an insulator at an elevated temperature, thus interrupting current flow to prevent thermal runaway caused by internal short circuits. The material is placed within the cell, as a thin layer incorporated within the anode and/or the cathode, to control excess currents from metal-to-metal or metal-to-carbon shorts that might result from cell crush or a manufacturing defect. The safety of high-rate cells is thus improved, preventing serious injury to personnel and sensitive equipment located near the battery. The use of recently available nanoscale particles of nickel and Teflon permits an improved, homogeneous material with the potential to be fine-tuned to a unique switch temperature, sufficiently below the onset of a catastrophic chemical reaction. The smaller particles also permit the formation of a thinner control film layer (<50 m), which can be incorporated into commercial high-rate lithium primary and secondary cells. The innovation permits incorporation in current lithium and lithium-ion cell designs with a minimal impact on cell weight and volume. The composite thermal switch (CTS(TradeMark)) coating can be incorporated in either the anode or cathode or both. The coating can be applied in a variety of different processes that permits incorporation in the cell and electrode manufacturing processes. The CTS responds quickly and halts current flow in the hottest parts of the cell first. The coating can be applied to metal foil and supplied as a cell component onto which the active electrode materials are coated.

McDonald, Robert; Brawn, Shelly; Harrison, Katherine; O'Toole, Shannon; Moeller, Michael

2011-01-01

203

The packet switching brain.  

PubMed

The computer metaphor has served brain science well as a tool for comprehending neural systems. Nevertheless, we propose here that this metaphor be replaced or supplemented by a new metaphor, the "Internet metaphor," to reflect dramatic new network theoretic understandings of brain structure and function. We offer a "weak" form and a "strong" form of this metaphor: The former suggests that structures and processes unique to Internet-like architectures (e.g., domains and protocols) can profitably guide our thinking about brains, whereas the latter suggests that one particular feature of the Internet-packet switching-may be instantiated in the structure of certain brain networks, particularly mammalian neocortex. PMID:20350173

Graham, Daniel; Rockmore, Daniel

2011-02-01

204

Laparoscopic Duodenal Switch  

Microsoft Academic Search

Laparoscopic biliopancreatic diversion with duodenal switch (BPD-DS) is one of the most effective weight loss procedures currently\\u000a available. Both short- and long-term weight loss exceed that of any other bariatric operation. BPD-DS involves a 150- to 200-cc\\u000a sleeve or vertical gastrectomy, a duodenoileal anastomosis, and a long Roux-en-Y with a 150-cm alimentary limb and a 100-cm\\u000a common channel (Fig. 14.1).

Manish Parikh; Michel Gagner; Alfons Pomp

205

Switching biologic agents for uveitis  

Microsoft Academic Search

PurposeTo observe whether switching between biological agents helps to gain or maintain uveitis remission in cases with sight-threatening refractory uveitis.MethodsWe reviewed the case notes of seven patients with refractory uveitis, who had switched between biological agents. The switch between biological agents (infliximab or adalimumab) was for gaining control of systemic symptoms, uveitis, or for the ease of administration.ResultsThere were three

N Dhingra; J Morgan; A D Dick

2009-01-01

206

Component Processes in Task Switching  

Microsoft Academic Search

Participants switched between two randomly ordered, two-choice reaction-time (RT) tasks, where an instructional cue preceded the target stimulus and indicated which task to execute. Task-switching cost dissipated passively while the participants waited for the instructional cue in order to know which task to execute (during the Response–Cue Interval). Switching cost was sharply reduced, but not abolished, when the participants actively

Nachshon Meiran; Ziv Chorev; Ayelet Sapir

2000-01-01

207

Thinking Critically about Critical Thinking  

ERIC Educational Resources Information Center

As a philosophy professor, one of my central goals is to teach students to think critically. However, one difficulty with determining whether critical thinking can be taught, or even measured, is that there is widespread disagreement over what critical thinking actually is. Here, I reflect on several conceptions of critical thinking, subjecting…

Mulnix, Jennifer Wilson

2012-01-01

208

Heat pipe thermal switch  

NASA Technical Reports Server (NTRS)

A thermal switch for controlling the dissipation of heat between a body is described. The thermal switch is comprised of a flexible bellows defining an expansible vapor chamber for a working fluid located between an evaporation and condensation chamber. Inside the bellows is located a coiled retaining spring and four axial metal mesh wicks, two of which have their central portions located inside of the spring while the other two have their central portions located between the spring and the side wall of the bellows. The wicks are terminated and are attached to the inner surfaces of the outer end walls of evaporation and condensation chambers respectively located adjacent to the heat source and heat sink. The inner surfaces of the end walls furthermore include grooves to provide flow channels of the working fluid to and from the wick ends. The evaporation and condensation chambers are connected by turnbuckles and tension springs to provide a set point adjustment for setting the gap between an interface plate on the condensation chamber and the heat sink.

Wolf, D. A. (inventor)

1983-01-01

209

The AutoBlast Interrupter Switch  

Microsoft Academic Search

An air interrupter switch may be defined as a nonautomatic air switch which combines the functions of a disconnecting switch with the ability to interrupt current up to a predetermined magnitude. It primarily differs in function from a circuit breaker in that it cannot interrupt overload or short-circuit currents. General specifications for interrupter switches are proposed. The Auto-Blast interrupter switch

E. A. Williams; W. G. Harlow

1943-01-01

210

Fast Switched Backplane for a Gigabit Switched Router  

E-print Network

1 Fast Switched Backplane for a Gigabit Switched Router Nick McKeown Department of Electrical....................................................................................................................2 3 The Architecture of Internet Routers..............................................................................................................29 #12;2 2 Abstract There is a new trend in the architecture of high performance Internet routers

Ratnasamy, Sylvia

211

Tuning the temperature dependence for switching in dithienylethene photochromic switches.  

PubMed

Diarylethene photochromic switches use light to drive structural changes through reversible electrocyclization reactions. High efficiency in dynamic photoswitching is a prerequisite for applications, as is thermal stability and the selective addressability of both isomers ring-opened and -closed diarylethenes. These properties can be optimized readily through rational variation in molecular structure. The efficiency with regard to switching as a function of structural variation is much less understood, with the exception of geometric requirements placed on the reacting atoms. Ultimately, increasing the quantum efficiency of photochemical switching in diarylethenes requires a detailed understanding of the excited-state potential energy surface(s) and the mechanisms involved in switching. Through studies of the temperature dependence, photoswitching and theoretical studies demonstrate the occurrence or absence of thermal activation barriers in three constitutional isomers that bear distinct ?-conjugated systems. We found that a decrease in the thermal barriers correlates with an increase in switching efficiency. The origin of the barriers is assigned to the decrease in ?-conjugation that is concomitant with the progress of the photoreaction. Furthermore, we show that balanced molecular design can minimize the change in the extent of ?-conjugation during switching and lead to optimal bidirectional switching efficiencies. Our findings hold implications for future structural design of diarylethene photochromic switches. PMID:23889496

Kudernac, Tibor; Kobayashi, Takao; Uyama, Ayaka; Uchida, Kingo; Nakamura, Shinichiro; Feringa, Ben L

2013-08-29

212

Introduction to Photonic Packet Switching Yatindra Nath Singh  

E-print Network

in a switch - why optical packet switching? - switching in near future optical networks - basic switching Modern day switching devices (for backbone networks) IP Switches/ routers - example of packet switch ATM, YNS Photonic Packet Switching 8 Functions in a packet switch - routing - providing network

Singh Yatindra Nath

213

Switching efficiency improvement in spin torque majority gates  

NASA Astrophysics Data System (ADS)

Spin torque majority gate (STMG) is one of the promising options for beyond complementary metal-oxide-semiconductor logic. Improvement of its performance—switching speed vs. required current—is critical for its competitiveness. In this paper, (a) we identify an optimized layout of the gate comprised of thin magnetic wires with in-plane magnetization; (b) we optimize geometries of perpendicular magnetization spin torque majority gates. Micromagnetic simulations demonstrate an improvement in switching current for in-plane magnetization (with less than 1 ns switching time) from 6 mA in the original scheme to 1.5 mA in the present one. Additionally, failures of switching caused by vortex formation are eliminated and desired output magnetization is achieved. Various geometries of STMG with perpendicular magnetization are explored. The scheme with a straight cross proves to be the most advantageous. It is predicted to operate with the switching current of 50 ?A and less than 4 ns switching time.

Nikonov, Dmitri E.; Manipatruni, Sasikanth; Young, Ian A.

2014-05-01

214

Ferroelastic switching for nanoscale non-volatile magnetoelectric devices  

SciTech Connect

Multiferroics, where (anti-) ferromagnetic, ferroelectric, and ferroelastic order parameters coexist [1-5], enables manipulation of magnetic ordering by electric field through switching of the electric polarization [6-9]. It has been shown that realization of magnetoelectric coupling in single-phase multiferroic such as BiFeO3 requires ferroelastic (71o, 109o) rather than ferroelectric (180o) domain switching [6]. However, the control of such ferroleastic switching in a singlephase system has been a significant challenge as elastic interactions tend to destabilize small switched volumes, resulting in subsequent ferroelastic backswitching at zero electric field, thus disappearance of nonvolatile information storage [10, 11]. Guided by our phase-field simulations, we here report an approach to stabilize ferroelastic switching by eliminating the stress-induced instability responsible for back-switching using isolated monodomain BiFeO3islands. This work demonstrates a critical step to control and utilize nonvolatile magnetoelectric coupling at the nanoscale. Beyond magnetoelectric coupling, it provides a framework for exploring a route to control multiple order parameters coupled to ferroelastic order in other low-symmetry materials.

Baek, S. H.; Jang, H. W.; Folkman, C. M.; Li, Yulan; Winchester, B.; Zhang, J. X.; He, Q.; Chu, Y. H.; Nelson, C. T.; Rzchowski, M. S.; Pan, X. Q.; Ramesh, R.; Chen , L.Q.; Eom, C.B.

2010-04-01

215

EDITORIAL: Molecular switches at surfaces Molecular switches at surfaces  

NASA Astrophysics Data System (ADS)

In nature, molecules exploit interaction with their environment to realize complex functionalities on the nanometer length scale. Physical, chemical and/or biological specificity is frequently achieved by the switching of molecules between microscopically different states. Paradigmatic examples are the energy production in proton pumps of bacteria or the signal conversion in human vision, which rely on switching molecules between different configurations or conformations by external stimuli. The remarkable reproducibility and unparalleled fatigue resistance of these natural processes makes it highly desirable to emulate nature and develop artificial systems with molecular functionalities. A promising avenue towards this goal is to anchor the molecular switches at surfaces, offering new pathways to control their functional properties, to apply electrical contacts, or to integrate switches into larger systems. Anchoring at surfaces allows one to access the full range from individual molecular switches to self-assembled monolayers of well-defined geometry and to customize the coupling between molecules and substrate or between adsorbed molecules. Progress in this field requires both synthesis and preparation of appropriate molecular systems and control over suitable external stimuli, such as light, heat, or electrical currents. To optimize switching and generate function, it is essential to unravel the geometric structure, the electronic properties and the dynamic interactions of the molecular switches on surfaces. This special section, Molecular Switches at Surfaces, collects 17 contributions describing different aspects of this research field. They analyze elementary processes, both in single molecules and in ensembles of molecules, which involve molecular switching and concomitant changes of optical, electronic, or magnetic properties. Two topical reviews summarize the current status, including both challenges and achievements in the field of molecular switches on metal surfaces, focusing on electronic and vibrational spectroscopy in one case and scanning tunneling microscopy studies in the other. Original research articles describe results in many aspects of the field, including: Self-assembly, self-organization, and controlled growth of molecular layers on various substrates. Highly-ordered arrays provide model systems with extraordinary structural properties, allowing one to adjust interactions between molecules and between molecule and substrate, and can be robustly prepared from solution, an essential prerequisite for applications. Conformational or electronic switching of molecules adsorbed at metal and semiconductor surfaces. These studies highlight the elementary processes governing molecular switching at surfaces as well as the wide range of possible stimuli. Carbon-based substrates such as graphene or carbon nanotubes. These substrates are attractive due to their effective two-dimensionality which implies that switching of adsorbed molecules can effect a significant back-action on the substrate. Mechanisms of conformational switching. Several contributions study the role of electron-vibron coupling and heating in current-induced conformational switching. We hope that the collection of articles presented here will stimulate and encourage researchers in surface physics and interfacial chemistry to contribute to the still emerging field of molecular switches at surfaces. We wish to acknowledge the support and input from many colleagues in preparing this special section. A significant part of this work has been conducted in the framework of the Sonderforschungsbereich 658 Elementary Processes in Molecular Switches at Surfaces of the Deutsche Forschungsgemeinschaft, to which we are grateful for financial support. Molecular surfaces at switches contents Molecular switches at surfacesMartin Weinelt and Felix von Oppen Optically and thermally induced molecular switching processes at metal surfacesPetra Tegeder Effects of electron-vibration coupling in transport through single moleculesKatharina J Franke and Jose Ignaci

Weinelt, Martin; von Oppen, Felix

2012-10-01

216

A high capacity satellite switched TDMA microwave switch matrix  

NASA Technical Reports Server (NTRS)

A description is given of the conceptual design of a high-capacity satellite switched-time division multiple access (SS-TDMA) microwave switch matrix fabricated with GaAs monolithic microwave integrated circuits (MMICs), including integration of both microwave and control logic circuits into the monolithic design. The technology required for a 30/20 GHz communications system includes an on-board SS-TDMA switch matrix. A conceptual design study that has been completed for a wideband, high-capacity (typically 100 x 100) channel switch matrix using technology anticipated for 1987 is described, noting that the study resulted in a switch matrix design concept using a coupled crossbar architecture implemented with MMIC. The design involves basic building block MMIC, permitting flexible growth and efficient wraparound redundancy to increase reliability.

Cory, B. J.; Berkowitz, M.

1981-01-01

217

The reactivity of ortho-methoxy-substituted catechol radicals with sulfhydryl groups: contribution for the comprehension of the mechanism of inhibition of NADPH oxidase by apocynin.  

PubMed

Redox processes are involved in the mechanism of action of NADPH oxidase inhibitors such as diphenyleneiodonium and apocynin. Here, we studied the structure-activity relationship for apocynin and analogous ortho-methoxy-substituted catechols as inhibitors of the NADPH oxidase in neutrophils and their reactivity with peroxidase. Aiming to alter the reduction potential, the ortho-methoxy-catechol moiety was kept constant and the substituents at para position related to the hydroxyl group were varied. Two series of compounds were employed: methoxy-catechols bearing electron-withdrawing groups (MC-W) such as apocynin, vanillin, 4-nitroguaiacol, 4-cyanoguaiacol, and methoxy-catechol bearing electron-donating groups (MC-D) such as 4-methylguaiacol and 4-ethylguaiacol. We found that MC-D were weaker inhibitors compared to MD-W. Furthermore, the radicals generated by oxidation of MC-W via MPO/H(2)O(2), but not for MC-D, were able to oxidize glutathione (GSH) as verified by the formation of thiyl radicals, depletion of GSH, and recycling of the ortho-methoxy-catechols during their oxidations. The capacity of oxidizing sulfhydryl (SH) groups was also verified when ovalbumin was incubated with MC-W, but not for MC-D. Since the effect of apocynin has been correlated with inactivation of the cytosolic fractions of the NADPH oxidase complex and its oxidation during the inhibitory process develops a special role in this process, we suggest that the close relationship between the reactivity of the radicals of MC-W compounds with thiol groups and their efficacy as NADPH oxidase inhibitor could be the chemical pathway behind the mechanism of action of apocynin and should be taken into account in the design of new and specific NADPH oxidase inhibitors. PMID:17544376

Kanegae, Marília P P; da Fonseca, Luiz Marcos; Brunetti, Iguatemy L; Silva, Sueli de Oliveira; Ximenes, Valdecir F

2007-08-01

218

The yin of exofacial protein sulfhydryls and the yang of intracellular glutathione in in vitro transfection with SS14 bioreducible lipoplexes.  

PubMed

Although redox-sensitive transfectants have been considered hitherto as the Holy Grail of gene delivery because of their ability to restrict the release of nucleic acids to intracellular compartments, the reasons for their sometimes lackluster performance do not seem likewise clear. To ascertain the possible influence of extracellular soluble thiols, exofacial protein sulfhydryls (EPTs) and glutathione (GSH) on the overall efficacy of bioreducible lipoplexes, we utilized a cationic gemini surfactant--SS14--in which the two single-chain amphiphiles are held together by a suitable redox-sensitive linkage. We herein draw a big picture whereby the interaction of bioreducible lipoplexes with cells and their internalization are tightly coupled events that ultimately do affect transfection. Specifically, we provide evidence that EPTs entail the reduction-triggered disruption of SS14 lipoplexes in plain Dulbecco's Modified Eagle Medium (DMEM), thereby resulting in a considerable waste (ca. 30%) of nucleic acids and low transgene expression. The DNA release from bioreducible lipoplexes can be blunted to ca. 16% by transfecting cells in complete medium and fully reverted by preincubating them for 1h before delivery in the same culture supernatant (i.e. preconditioning), thus significantly increasing transfection by ca. 3-fold and 10-fold, respectively. These results lead to the proposal of the protein corona as the central mediator in shielding SS14 bioreducible lipoplexes from the action of EPTs in the early phase of delivery and provide a smart solution as to how to increase their efficacy. Besides, we pinpoint associations between intracellular GSH levels and the extent of transfection. All these issues were unique to bioreducible lipoplexes. PMID:23123189

Pezzoli, Daniele; Zanda, Matteo; Chiesa, Roberto; Candiani, Gabriele

2013-01-10

219

Executive Control in Set Switching: Residual Switch Cost and Task-set Inhibition  

Microsoft Academic Search

Executive processes necessary for flexibly switching between different tasks were studied using a set switching paradigm that requires participants to rapidly switch between different tasks across consecutive trials. Switch cost reflects poorer performance for task-switch trials than for consecutive same-task trials. Significant switch cost was observed even with considerable preparation time before a task-switch, an effect known as residual switch

KATHERINE ARBUTHNOTT; JANIS FRANK

2000-01-01

220

Study of optoelectronic switch for satellite-switched time-division multiple access  

NASA Technical Reports Server (NTRS)

The use of optoelectronic switching for satellite switched time division multiple access will improve the isolation and reduce the crosstalk of an IF switch matrix. The results are presented of a study on optoelectronic switching. Tasks include literature search, system requirements study, candidate switching architecture analysis, and switch model optimization. The results show that the power divided and crossbar switching architectures are good candidates for an IF switch matrix.

Su, Shing-Fong; Jou, Liz; Lenart, Joe

1987-01-01

221

Switched Broadband Services For The Home  

NASA Astrophysics Data System (ADS)

In considering the deployment of fiber optics to the residence, two critical questions arise: what are the leading services that could be offered to justify the required investment; and what is the nature of the business that would offer these services to the consumer ? This talk will address these two questions together with the related issue of how the "financial engine" of today's television distribution infrastructure - TV advertising - would be affected by an open access system based on fiber optics coupled with broadband switching. On the business side, the talk concludes that the potential for open ended capacity expansion, fair competition between service providers, and new interactive services inherent in an open access, switched broadband system are the critical items in differentiating it from existing video and TV distribution systems. On the question of broadband services, the talk will highlight several new opportunities together with some findings from recent market research conducted by BNR. The talk will show that there are variations on existing services plus many new services that could be offered and which have real consumer appeal. The postulated open access system discussed here is visualized as having ultimately 1,000 to 2,000 video channels available to the consumer. Although this may appear to hopelessly fragment the TV audience and destroy the current TV advertising infrastructure, the technology of open access, switched broadband will present many new advertising techniques, which have the potential to be far more effective than those available today. Some of these techniques will be described in this talk.

Sawyer, Don M.

1990-01-01

222

Phenotypic switching in bacteria  

NASA Astrophysics Data System (ADS)

Living matter is a non-equilibrium system in which many components work in parallel to perpetuate themselves through a fluctuating environment. Physiological states or functionalities revealed by a particular environment are called phenotypes. Transitions between phenotypes may occur either spontaneously or via interaction with the environment. Even in the same environment, genetically identical bacteria can exhibit different phenotypes of a continuous or discrete nature. In this thesis, we pursued three lines of investigation into discrete phenotypic heterogeneity in bacterial populations: the quantitative characterization of the so-called bacterial persistence, a theoretical model of phenotypic switching based on those measurements, and the design of artificial genetic networks which implement this model. Persistence is the phenotype of a subpopulation of bacteria with a reduced sensitivity to antibiotics. We developed a microfluidic apparatus, which allowed us to monitor the growth rates of individual cells while applying repeated cycles of antibiotic treatments. We were able to identify distinct phenotypes (normal and persistent) and characterize the stochastic transitions between them. We also found that phenotypic heterogeneity was present prior to any environmental cue such as antibiotic exposure. Motivated by the experiments with persisters, we formulated a theoretical model describing the dynamic behavior of several discrete phenotypes in a periodically varying environment. This theoretical framework allowed us to quantitatively predict the fitness of dynamic populations and to compare survival strategies according to environmental time-symmetries. These calculations suggested that persistence is a strategy used by bacterial populations to adapt to fluctuating environments. Knowledge of the phenotypic transition rates for persistence may provide statistical information about the typical environments of bacteria. We also describe a design of artificial genetic networks that would implement a more general theoretical model of phenotypic switching. We will use a new cloning strategy in order to systematically assemble a large number of genetic features, such as site-specific recombination components from the R64 plasmid, which invert several coexisting DNA segments. The inversion of these segments would lead to discrete phenotypic transitions inside a living cell. These artificial phenotypic switches can be controlled precisely in experiments and may serve as a benchmark for their natural counterparts.

Merrin, Jack

223

IP switching and gigabit routers  

Microsoft Academic Search

To cope with the growth in the Internet and corporate IP networks, we require IP routers capable of much higher performance than is possible with existing architectures. This article examines two approaches to the design of a high-performance router, the gigabit router and the IP switch, and then provides some detail on the implementation of an IP switch and the

P. Newman; G. Minshall; T. Lyon; L. Huston

1997-01-01

224

Performance evaluation of transoceanic switching  

Microsoft Academic Search

The method of synchronous digital hierarchy self-healing ring (SDH SHR) in submarine operation is being developed to improve the reliability of international submarine optical communications. Transoceanic switching is applied in SDH SHR because of the unique features of an international optical submarine cable network: longer distance, submarine environment and fewer terminal stations. We study the system performance of transoceanic switching.

Du Yingzi; Hao Weimin

1998-01-01

225

s s 1 SECTIONALISING SWITCH  

E-print Network

AN OPEN SWITCH TO FORM A LOOP DETERMINE THE OPTIMAL FLOW PATTERN IN THE LOOP OPEN THE SWITCH CARRYING 22 23 24 25 26 27 28 2930 31 32 33 72 3435 36 44 45 46 47 48 49 50515253 54 55565758 59 6061 62 63 64

Sivaramakrishnan, Kartik K.

226

Basic Switching George Mason University  

E-print Network

and protocols for low and high speed digital packet networks (e.g. Ethernet, Frame Relay, MPLS, MPLS L3VPNs that involve configuring switches and routers. Course Text (Optional): Data Communications and NetworkingTCOM 514 Basic Switching George Mason University Summer 2011 Class Meeting Time and Location

227

Switching Matrix For Optical Signals  

NASA Technical Reports Server (NTRS)

Proposed matrix of electronically controlled shutters switches signals in optical fibers between multiple input and output channels. Size, weight, and power consumption reduced. Device serves as building block for small, low-power, broad-band television- and data-signal-switching systems providing high isolation between nominally disconnected channels.

Grove, Charles H.

1990-01-01

228

Breathalyzer enabled ignition switch system  

Microsoft Academic Search

Breath alcohol detector or better known as breathalyzer plays a vital role in monitoring alcohol concentration in a person's bloodstream. This project involves the design and development of breathalyzer device which controls ignition switch. The hardware modules include the PIC16F877A microcontroller, alcohol sensor, LCD panel and ignition switch circuitry. The software component includes the programming and source code which is

H. Abdul Rahim; S. D. S. Hassan

2010-01-01

229

Switch evaluation test system for the National Ignition Facility  

SciTech Connect

Flashlamp pumped lasers use pulsed power switches to commute energy stored in capacitor banks to the flashlamps. The particular application in which the authors are interested is the National Ignition Facility (NIF), being designed by Lawrence Livermore National Laboratory, Los Alamos National Laboratory, and Sandia National Laboratories (SNL). To lower the total cost of these switches, SNL has a research program to evaluate large closing switches. The target value of the energy switched by a single device is 1.6 MJ, from a 6 mF, 24kV capacitor bank. The peak current is 500 kA. The lifetime of the NIF facility is 24,000 shots. There is no switch today proven at these parameters. Several short-lived switches (100`s of shots) exist that can handle the voltage and current, but would require maintenance during the facility life. Other type devices, notably ignitrons, have published lifetimes in excess of 20,000 shots, but at lower currents and shorter pulse widths. The goal of the experiments at SNL is to test switches with the full NIF wave shape, and at the correct voltage. The SNL facility can provide over 500 kA at 24 kV charge voltage. the facility has 6.4 mF total capacitance, arranged in 25 sub-modules. the modular design makes the facility more flexible (for possible testing at lower current) and safer. For pulse shaping (the NIF wave shape is critically damped) there is an inductor and resistor for each of the 25 modules. Rather than one large inductor and resistor, this lowers the current in the pulse shaping components, and raises their value to those more easily attained with lumped inductors and resistors. The authors show the design of the facility, and show results from testing conducted thus far. They also show details of the testing plan for high current switches.

Savage, M.E.; Simpson, W.W. [Sandia National Labs., Albuquerque, NM (United States). High Energy Plasma Physics Dept.; Sharpe, R.A. [Sandia National Labs., Albuquerque, NM (United States). High Energy Plasma Physics Dept.]|[Ktech Corp., Albuquerque, NM (United States); Reynolds, F.D. [Sandia National Labs., Albuquerque, NM (United States). High Energy Plasma Physics Dept.]|[Tektronix, Inc., Albuquerque, NM (United States)

1997-07-01

230

Critic Markup  

NSDL National Science Digital Library

Everyone's a critic, but some of those critics use Markdown, Sublime Text, or other text editors instead of word. The CriticMarkup tool allows authors and editors to track changes to documents in plain text, which is most useful. Visitors can use the program to highlight insertions, deletions, substitutions, and comments. To see a full list of tools that Critic Markup is integrated with, visit the website.

Hess, Erik; Weatherhead, Gabe

2013-06-27

231

Toggling Bistable Atoms via Mechanical Switching of Bond Angle  

NASA Astrophysics Data System (ADS)

We reversibly switch the state of a bistable atom by direct mechanical manipulation of bond angle using a dynamic force microscope. Individual buckled dimers at the Si(100) surface are flipped via the formation of a single covalent bond, actuating the smallest conceivable in-plane toggle switch (two atoms) via chemical force alone. The response of a given dimer to a flip event depends critically on both the local and nonlocal environment of the target atom—an important consideration for future atomic scale fabrication strategies.

Sweetman, Adam; Jarvis, Sam; Danza, Rosanna; Bamidele, Joseph; Gangopadhyay, Subhashis; Shaw, Gordon A.; Kantorovich, Lev; Moriarty, Philip

2011-04-01

232

Sonic crystal acoustic switch device.  

PubMed

This study reports a wave-controlled sonic crystal switch device that exhibits a destructive interference-based wave to wave reverse switching effect. By applying control waves, this acoustic device, composed of a two-dimensional square lattice sonic crystal block, reduces acoustic wave transmission from input to output. The finite difference time domain simulation and experimental results confirm the wave-to-wave reverse switching effect at the peak frequencies of the second band. The proposed sonic crystal switch prototype provides a contrast rate of 86% at 11.3 kHz frequency. This wave-to-wave switching effect is useful for controlling wave propagation for smart structure applications. PMID:23742444

Alagoz, Serkan; Alagoz, Baris Baykant

2013-06-01

233

Optimized scalable network switch  

DOEpatents

In a massively parallel computing system having a plurality of nodes configured in m multi-dimensions, each node including a computing device, a method for routing packets towards their destination nodes is provided which includes generating at least one of a 2m plurality of compact bit vectors containing information derived from downstream nodes. A multilevel arbitration process in which downstream information stored in the compact vectors, such as link status information and fullness of downstream buffers, is used to determine a preferred direction and virtual channel for packet transmission. Preferred direction ranges are encoded and virtual channels are selected by examining the plurality of compact bit vectors. This dynamic routing method eliminates the necessity of routing tables, thus enhancing scalability of the switch.

Blumrich, Matthias A. (Ridgefield, CT); Chen, Dong (Croton On Hudson, NY); Coteus, Paul W. (Yorktown Heights, NY); Gara, Alan G. (Mount Kisco, NY); Giampapa, Mark E. (Irvington, NY); Heidelberger, Philip (Cortlandt Manor, NY); Steinmacher-Burow, Burkhard D. (Mount Kisco, NY); Takken, Todd E. (Mount Kisco, NY); Vranas, Pavlos M. (Bedford Hills, NY)

2007-12-04

234

Automatic thermal switch  

NASA Technical Reports Server (NTRS)

An automatic thermal switch to control heat flow includes a first thermally conductive plate, a second thermally conductive plate and a thermal transfer plate pivotally mounted between the first and second plates. A phase change power unit, including a plunger connected to the transfer plate, is in thermal contact with the first thermally conductive plate. A biasing element, connected to the transfer plate, biases the transfer plate in a predetermined position with respect to the first and second plates. When the phase change power unit is actuated by an increase in heat transmitted through the first plate, the plunger extends and pivots the transfer plate to vary the thermal conduction between the first and second plates through the transfer plate. The biasing element, transfer plate and piston can be arranged to provide either a normally closed or normally open thermally conductive path between the first and second plates.

Wing, L. D.; Cunningham, J. W. (inventors)

1981-01-01

235

MIRO Calibration Switch Mechanism  

NASA Technical Reports Server (NTRS)

The Jet Propulsion Laboratory has designed, analyzed, built, and tested a calibration switch mechanism for the MIRO instrument on the ROSETTA spacecraft. MIRO is the Microwave Instrument for the Rosetta Orbiter; this instrument hopes to investigate the origin of the solar system by studying the origin of comets. Specifically, the instrument will be the first to use submillimeter and millimeter wave heterodyne receivers to remotely examine the P-54 Wirtanen comet. In order to calibrate the instrument, it needs to view a hot and cold target. The purpose of the mechanism is to divert the instrument's field of view from the hot target, to the cold target, and then back into space. This cycle is to be repeated every 30 minutes for the duration of the 1.5 year mission. The paper describes the development of the mechanism, as well as analysis and testing techniques.

Suchman, Jason; Salinas, Yuki; Kubo, Holly

2001-01-01

236

High voltage coaxial switch  

DOEpatents

A coaxial high voltage, high current switch having a solid cylindrical cold cathode coaxially surrounded by a thin hollow cylindrical inner electrode and a larger hollow cylindrical outer electrode. A high voltage trigger between the cathode and the inner electrode causes electrons to be emitted from the cathode and flow to the inner electrode preferably through a vacuum. Some of the electrons penetrate the inner electrode and cause a volumetric discharge in the gas (which may be merely air) between the inner and outer electrodes. The discharge provides a low impedance path between a high voltage charge placed on the outer electrode and a load (which may be a high power laser) coupled to the inner electrode. For high repetition rate the gas between the inner and outer electrodes may be continuously exchanged or refreshed under pressure. 3 figs.

Rink, J.P.

1983-07-19

237

Critically Thinking about Critical Thinking  

ERIC Educational Resources Information Center

In this article, the author states that "critical thinking" has mesmerized academics across the political spectrum and that even high school students are now being called upon to "think critically." He furthers adds that it is no exaggeration to say that "critical thinking" has quickly evolved into a scholarly…

Weissberg, Robert

2013-01-01

238

Critical Thinking vs. Critical Consciousness  

ERIC Educational Resources Information Center

This article explores four kinds of critical thinking. The first is found in Socratic dialogues, which employ critical thinking mainly to reveal logical fallacies in common opinions, thus cleansing superior minds of error and leaving philosophers free to contemplate universal verities. The second is critical interpretation (hermeneutics) which…

Doughty, Howard A.

2006-01-01

239

Investigation of fullerenes for high speed low latency, photonic switching  

SciTech Connect

The components in high-speed, all-optical photonic systems must satisfy two essential requirements: (1) high switching speeds in the range of Tbit/s, and (2) low latency, where the latency is the amount of time that the optical signal remains in the device. An important problem precluding the practical implementation of high-speed, all- optical switching is the lack of a material with appropriate nonlinear optical properties needed to effect the switching. Numerous material systems have been studied in the past, but none have met all the necessary requirements. Development of such a material and its incorporation into photonic devices would advance the field tremendously. This Lab-wide LDRD project resolved this critical problem.

Lee, H. W. H; Shelton, R.N. [California Univ., Davis, CA (United States)

1997-02-13

240

Switch dynamics for stochastic model of genetic toggle switch  

NASA Astrophysics Data System (ADS)

Recently, more and more biological experiments have indicated that noise plays an important role in bistable systems, such as the case of the bimodal population distribution in the genetic toggle switch. In this paper, we further verify that noises in degradation rates can indeed induce switching in the genetic toggle switch. Meanwhile, we apply the theory of mean first passage time (MFPT) in high dimensional system to the above stochastic model. According to our assumption, the high order finite difference method is used to compute the MFPT (that the average time switching from one steady state to the other) and we find that the relationship between the MFPT and noise intensity is negative correlation. The result is also verified through another numerical simulation method.

Xu, Yong; Zhu, Ya-nan; Shen, Jianwei; Su, Jianbin

2014-12-01

241

Engineering precision RNA molecular switches  

PubMed Central

Ligand-specific molecular switches composed of RNA were created by coupling preexisting catalytic and receptor domains via structural bridges. Binding of ligand to the receptor triggers a conformational change within the bridge, and this structural reorganization dictates the activity of the adjoining ribozyme. The modular nature of these tripartite constructs makes possible the rapid construction of precision RNA molecular switches that trigger only in the presence of their corresponding ligand. By using similar enzyme engineering strategies, new RNA switches can be made to operate as designer molecular sensors or as a new class of genetic control elements. PMID:10097080

Soukup, Garrett A.; Breaker, Ronald R.

1999-01-01

242

Switching behavior of different contact materials under capacitive switching conditions  

Microsoft Academic Search

For vacuum circuit-breakers capacitive current switching means a specific operating condition. Though it differs notably from the short-circuit current interruption situation, the circuit-breaker design needs to be reconsidered and adapted. Capacitive switching combines high inrush-currents at the connection of a capacitive load and considerable low breaking currents at its disconnection. A reliable dielectric performance of the breaker is required since

Florian Körner; Manfred Lindmayer; Michael Kurrat; Dietmar Gentsch

2008-01-01

243

Task Switching versus Cue Switching: Using Transition Cuing to Disentangle Sequential Effects in Task-Switching Performance  

ERIC Educational Resources Information Center

Recent methodological advances have allowed researchers to address confounds in the measurement of task-switch costs in task-switching performance by dissociating cue switching from task switching. For example, in the transition-cuing procedure, which involves presenting cues for task transitions rather than for tasks, cue transitions (cue…

Schneider, Darryl W.; Logan, Gordon D.

2007-01-01

244

Critical Dynamics  

NASA Astrophysics Data System (ADS)

Part I. Near-Equilibrium Critical Dynamics: 1. Equilibrium critical phenomena; 2. Stochastic dynamics; 3. Dynamic scaling; 4. Dynamic perturbation theory; 5. Dynamic renormalization group; 6. Hydrodynamic modes and reversible mode couplings; 7. Phase transitions in quantum systems; Part II. Scale Invariance in Non-Equilibrium Systems; 8. Non-equilibrium critical dynamics; 9. Reaction-diffusion systems; 10. Active to absorbing state transitions; 11. Driven diffusive systems and growing interfaces; Index.

Täuber, Uwe C.

2014-03-01

245

Heteroleptic Copper Switches  

PubMed Central

Heteroleptic copper compounds have been designed and synthesized on solid supports. Chemical redox agents were used to change the oxidation state of the SiO2-immobilized heteroleptic copper compounds from Cu(I) to Cu(II) and then back to Cu(I). Optical spectroscopy of a dimethyl sulfoxide (DMSO) suspension demonstrated the reversibility of the Cu(I)/Cu(II) SiO2-immobilized compounds by monitoring the metal-to-ligand charge transfer (MLCT) peak at about 450 nm. EPR spectroscopy was used to monitor the isomerization of Cu(I) tetrahedral to Cu(II) square planar. This conformational change corresponds to a 90° rotation of one ligand with respect to the other. Conductive AFM (cAFM) and macroscopic gold electrodes were used to study the electrical properties of a p+ Si-immobilized heteroleptic copper compound where switching between the Cu(I)/Cu(II) states occurred at ?0.8 and +2.3 V. PMID:20964417

Kabehie, Sanaz; Xue, Mei; Stieg, Adam Z.; Liong, Monty; Wang, Kang L.

2013-01-01

246

Regenerative switching CMOS system  

DOEpatents

Complementary Metal Oxide Semiconductor (CMOS) Schottky barrier Field Effect Transistor systems, which are a series combination of N and P-Channel MOSFETS, in which Source Schottky barrier junctions of the N and P-Channel Schottky barrier MOSFETS are electrically interconnected, (rather than the Drains as in conventional diffused junction CMOS), which Schottky barrier MOSFET system demonstrates Regenerative Inverting Switching Characteristics in use are disclosed. Both the N and P-Channel Schottky barrier MOSFET devices are unique in that they provide operational Drain Current vs. Drain to Source voltage as a function of Gate voltage only where the polarities of the Drain voltage and Gate voltage are opposite, referenced to the Source as a common terminal, and where the polarity of the voltage applied to the Gate is appropriate to cause Channel inversion. Experimentally derived results which demonstrate and verify the operation of N and P-Channel Schottky barrier MOSFETS actually fabricated on P and N-type Silicon respectively, by a common procedure using vacuum deposited Chromium as a Schottky barrier forming metal, are also provided. 14 figs.

Welch, J.D.

1998-06-02

247

Regenerative switching CMOS system  

DOEpatents

Complementary Metal Oxide Semiconductor (CMOS) Schottky barrier Field Effect Transistor systems, which are a seriesed combination of N and P-Channel MOSFETS, in which Source Schottky barrier junctions of the N and P-Channel Schottky barrier MOSFETS are electically interconnected, (rather than the Drains as in conventional diffused junction CMOS), which Schottky barrier MOSFET system demonstrates Regenerative Inverting Switching Characteristics in use are disclosed. Both the N and P-Channel Schottky barrier MOSFET devices are unique in that they provide operational Drain Current vs. Drain to Source voltage as a function of Gate voltage only where the polarities of the Drain voltage and Gate voltage are opposite, referenced to the Source as a common terminal, and where the polarity of the voltage applied to the Gate is appropriate to cause Channel inversion. Experimentally derived results which demonstrate and verify the operation of N and P-Channel Schottky barrier MOSFETS actually fabricated on P and N-type Silicon respectively, by a common procedure using vacuum deposited Chromium as a Schottky barrier forming metal, are also provided.

Welch, James D. (10328 Pinehurst Ave., Omaha, NE 68124)

1998-01-01

248

49 CFR 236.342 - Switch circuit controller.  

Code of Federal Regulations, 2012 CFR

...342 Switch circuit controller. Switch circuit controller connected at the point to switch, derail, or movable-point frog, shall be maintained so that its contacts will not be in position corresponding to switch point closure when switch point...

2012-10-01

249

49 CFR 236.342 - Switch circuit controller.  

Code of Federal Regulations, 2011 CFR

...342 Switch circuit controller. Switch circuit controller connected at the point to switch, derail, or movable-point frog, shall be maintained so that its contacts will not be in position corresponding to switch point closure when switch point...

2011-10-01

250

49 CFR 236.342 - Switch circuit controller.  

Code of Federal Regulations, 2013 CFR

...342 Switch circuit controller. Switch circuit controller connected at the point to switch, derail, or movable-point frog, shall be maintained so that its contacts will not be in position corresponding to switch point closure when switch point...

2013-10-01

251

49 CFR 236.342 - Switch circuit controller.  

Code of Federal Regulations, 2010 CFR

...342 Switch circuit controller. Switch circuit controller connected at the point to switch, derail, or movable-point frog, shall be maintained so that its contacts will not be in position corresponding to switch point closure when switch point...

2010-10-01

252

Frequency switching in a relativistic magnetron with diffraction output  

NASA Astrophysics Data System (ADS)

Symmetric axial extraction of radiation from a relativistic magnetron with diffraction output (MDO) facilitates the use of any eigenmode as the operating one. As a consequence, a relatively small input RF signal can be used for mode switching, unlike the case for asymmetric extraction when only non-degenerate modes (the ? - mode or the 2?- mode) can be used as the operating one. Using the MAGIC particle-in-cell code we demonstrate that about 180 MW is required to switch these non-degenerate modes in the well-known 400 kV A6 magnetron with extraction of radiation from one of its cavities when driven by a solid cathode, and about 30 MW is required for the same device when driven by a transparent cathode. For the gigawatt A6 MDO with a transparent cathode, however, only 200-300 kW is sufficient for mode switching and the switched mode continues to be generated after elimination of the input short RF signal when the amplitude of the applied axial magnetic field is near the critical value corresponding to the boundary between synchronous regions for neighboring modes. In repetitively pulsed systems, in order to switch each subsequent pulse independent of the previous one, the time between voltage pulses must be chosen to be not less than 20-30 ns (the time for the stored electromagnetic energy to flow out of the cavity) so that decreasing the output power of the previous pulse cannot switch the subsequent pulse. Finally, using this mode switching technique, we demonstrate the possibility of generating short gigawatt microwave pulses with different frequency and polarization by using a short, weak, single frequency signal that is very attractive for radar applications.

Liu, Meiqin; Liu, Chun-Liang; Galbreath, David; Michel, Cedric; Prasad, Sarita; Fuks, Mikhail I.; Schamiloglu, Edl

2011-08-01

253

Electron collisions in gas switches  

SciTech Connect

Many technologies rely on the conduction/insulation properties of gaseous matter for their successful operation. Many others (e.g., pulsed power technologies) rely on the rapid change (switching or modulation) of the properties of gaseous matter from an insulator to a conductor and vice versa. Studies of electron collision processes in gases aided the development of pulsed power gas switches, and in this paper we shall briefly illustrate the kind of knowledge on electron collision processes which is needed to optimize the performance of such switching devices. To this end, we shall refer to three types of gas switches: spark gap closing, self-sustained diffuse discharge closing, and externally-sustained diffuse discharge opening. 24 refs., 15 figs., 2 tabs.

Christophorou, L.G.

1989-01-01

254

Electromagnetic Activation of Capillary Switches  

NASA Astrophysics Data System (ADS)

By designing coupled droplet pairs with the appropriate length scale to promote surface tension as the dominant force, one can create bi-stable capillary switches. This bi-stability can be triggered by pressure pulses, surface chemistry, electroosmosis, or body forces. To exploit the latter, we designed a capillary switch with electromagnetic activation. The resulting setup consists of a sub-millimeter tube, overfilled with a ferrofluid, surrounded by a wire coil to generate a magnetic field. Evidence of this capillary switching will be presented along with some theoretical basis in fluid- and electro-dynamics. The approach may also be used to investigate other transport phenomena in electromagnetically-coupled microfluidic systems, including the relative effects of translational motion of the ferrofluid (both particles and solvent molecules) versus the rotational effects of the individual magnetic grains. These individually addressable capillary switches offer intriguing applications including high-speed adaptive optics, actuators at the microscale, and possible PCB integration.

Malouin, Bernie; Dayal, Rohan; Parsa, Leila; Hirsa, Amir

2008-11-01

255

Investigation of a hybrid optical-electronic switch supporting different service classes  

NASA Astrophysics Data System (ADS)

Optical fiber is considered the most competitive wired transmission support thanks to its low attenuation, wide optical bandwidth, long reach, and low cost. However, optics do not yet perform higher functionalities such as switching. In fact, all-optical switches face a contention issue, due to the lack of practical optical buffers. Thus, the switching function is still performed electronically, which requires energetically costly optical-to-electronic conversions. The energy consumption is a critical issue within the growing data traffic. Thus, a proposition of hybrid switch architecture supplementing optical switch with an electronic buffer. In this paper, we propose to investigate the performance of hybrid switch that supports different priority classes where the priority is defined in terms of Packet Loss Ratio (PLR). We show that the hybrid switch is a good trade off since it allows significant performance improvements towards a buffer-less all optical switch in terms of PLR and sustainable load, for relatively few electronic ports of the buffer, which would reduce energy consumption compared to an electronic switch.

Samoud, Wiem; Ware, Cédric; Lourdiane, Mounia

2014-09-01

256

Electrical switching in sol-gel-derived SiO2 films  

NASA Astrophysics Data System (ADS)

We have investigated electrical switching behavior of sol-gel derived SiO2 films in c-Si(p)/SiO2/metal structures. The SiO2 film is fabricated from silicafilm (a soluble Si polymer in dissolved in denatured alcohol) using spin-coating technique. The thickness of the film is in the range of 300~2000 Å which depends on both spinning speed and the degree of dilution. We find that, with Ag as the top contact, when the applied voltage reaches a critical value of 1.5 ~ 2.5 V, current increases rapidly many orders of magnitude higher, and an irreversible switching occurs. The switching is also found to be polarity-dependent. The switching occurs only when the top contact (Ag) is biased positively, indicating the switching involves diffusion or electromigration of Ag. Both switching voltage and current are found to scale with the top contact area of the device. The switching dynamics is studied using voltage-pulse over a duration of 300 ns to 500 ms and amplitude of 2 to 20 V. We find that the switching electrical field is strongly dependent of the delay time prior to switching, and not related to the film thickness.

Hu, Jian; Ward, Scott; Wang, Qi

2003-07-01

257

High PRF high current switch  

DOEpatents

A triggerable, high voltage, high current, spark gap switch for use in pu power systems. The device comprises a pair of electrodes in a high pressure hydrogen environment that is triggered by introducing an arc between one electrode and a trigger pin. Unusually high repetition rates may be obtained by undervolting the switch, i.e., operating the trigger at voltages much below the self-breakdown voltage of the device.

Moran, Stuart L. (Fredericksburg, VA); Hutcherson, R. Kenneth (College Park, MD)

1990-03-27

258

Bridges, Switches, Routers 1.1 Introduction  

E-print Network

Chapter 1 Bridges, Switches, Routers 1.1 Introduction ¯ Packet vs circuit (and virtual circuit ¯ Packet processors--Bridges, Routers, ATM switches 1 #12;2 CHAPTER 1. BRIDGES, SWITCHES, ROUTERS Routing in an extended LAN. See Problem 2. #12;4 CHAPTER 1. BRIDGES, SWITCHES, ROUTERS Figure 1.3: LAN vs VLAN topology

Varaiya, Pravin

259

WDM burst switching for petabit capacity routers  

Microsoft Academic Search

WDM burst switching is an approach to building very high capacity routing switches based on optical data paths and electronic control. Burst switches assign user data bursts to channels in WDM links on-the-fly in order to provide efficient statistical multiplexing of high rate data channels. The overall system architecture is designed to facilitate the introduction of optical switching components as

Yuhua Chen; Jonathan S. Turner

1999-01-01

260

Ferroelectric liquid crystal optical interconnect switching systems  

Microsoft Academic Search

This grant explored the possible use of ferroelectric liquid crystals (FLC's) in the reamization of photonic switching fabrics. Problems addressed included device fabrication, switch architectures, and switch performance. Experimental versions of most architectures were constructed. The aim of the contract was to develop techniques for using ferroelectric liquid crystals (FLC's) for novel photonic switching architectures. Initial work was devoted to

Joseph W. Goodman

1993-01-01

261

Optical Packet Switching -1 Optical Networks  

E-print Network

Optical Packet Switching - 1 Optical Networks: from fiber transmission to photonic switching Optical Packet Switching Fabio Neri and Marco Mellia TLC Networks Group ­ Electronics Department e networks · Network management, reliability and fault recovery · Optical packet switching #12;Optical Packet

Mellia, Marco

262

Adaptive Optical Burst Switching Thomas Bonald  

E-print Network

Adaptive Optical Burst Switching Thomas Bonald Telecom ParisTech Paris, France thomas.indre,sara.oueslati}@orange-ftgroup.com Abstract--We propose a modified version of Optical Burst Switching (OBS) that adapts the size of switched refer to this technique as Adaptive Optical Burst Switching. We prove that the proposed scheme

Bonald, Thomas

263

Micromachined RF Switch With High Mechanical Reliability.  

National Technical Information Service (NTIS)

For this project, MESA (MEMS Early-Stage Analysis) was implemented to develop ,'tri state multi-contact' switch. The switch was designed and processed to enhance mechanical and RF performance compare to the conventional RF MEMS switches. The switch was su...

K. Ishikawa, H. Mamiya, T. Miki, Q. Yu

2005-01-01

264

Wavelength conversion in optical packet switching  

Microsoft Academic Search

A detailed traffic analysis of optical packet switch design is performed. Special consideration is given to the complexity of the optical buffering and the overall switch block structure is considered in general. Wavelength converters are shown to improve the traffic performance of the switch blocks for both random and bursty traffic. Furthermore, the traffic performance of switch blocks with add-drop

Soeren Lykke Danielsen; Peter Bukhave Hansen; Kristian E. Stubkjaer

1998-01-01

265

Critical Muralism  

ERIC Educational Resources Information Center

This study focuses on the development and practices of Critical Muralists--community-educator-artist-leader-activists--and situates these specifically in relation to the Mexican mural tradition of los Tres Grandes and in relation to the history of public art more generally. The study examines how Critical Muralists address artistic and…

Rosette, Arturo

2009-01-01

266

Mapping L1 Ligase ribozyme conformational switch  

PubMed Central

L1 Ligase (L1L)molecular switch is an in vitro optimized synthetic allosteric ribozyme that catalyzes the regioselective formation of a 5’-to-3’ phosphodiester bond, a reaction for which there is no known naturally occurring RNA catalyst. L1L serves as a proof of principle that RNA can catalyze a critical reaction for prebiotic RNA self-replication according to the RNA World hypothesis. L1L crystal structure captures two distinct conformations that differ by a re-orientation of one of the stems by around 80 Å and are presumed to correspond to the active and inactive state, respectively. It is of great interest to understand the nature of these two states in solution, and the pathway for their interconversion. In this study, we use explicit solvent molecular simulation together with a novel enhanced sampling method that utilizes concepts from network theory to map out the conformational transition between active and inactive states of L1L. We find that the overall switching mechanism can be described as a 3-state/2-step process. The first step involves a large-amplitude swing that re-orients stem C. The second step involves the allosteric activation of the catalytic site through distant contacts with stem C. Using a conformational space network representation of the L1L switch transition, it is shown that the connection between the three states follows different topographical patterns: the stem C swing step passes through a narrow region of the conformational space network, whereas the allosteric activation step covers a much wider region and a more diverse set of pathways through the network. PMID:22771572

Giambasu, George M.; Lee, Tai-Sung; Scott, William G.; York, Darrin M.

2012-01-01

267

Characterizing Uniformly Ultimately Bounded Switching Signals for Uncertain Switched Linear Systems  

E-print Network

exhibit unbounded behaviors under some switching signals [15], [7]. Therefore, the first task here task here is to identify a subclass of admissible switching signals such that the switched system hasCharacterizing Uniformly Ultimately Bounded Switching Signals for Uncertain Switched Linear Systems

Antsaklis, Panos

268

Electrohydrostatics of Capillary Switches  

NASA Astrophysics Data System (ADS)

A pair of supported droplets that are coupled via a liquid filled cylindrical hole of radius R in a plate is referred to as a capillary switch (CS). A CS is known to exhibit two stable equilibrium states when the combined volume of the top and the bottom droplets is greater than 4/3 ?R^3. This fact is exploited in various applications, including optical lenses and adhesion, where the main challenge is to come up with a method to"toggle" the CS between the two stable states that is reliable, is energy efficient, and has fast response. The use of an electric field to achieve this purpose is explored here through simulations in which the axisymmetric shapes and stability of a CS are determined as a function of applied field strength. In the simulations, the liquid is taken to be perfectly conducting and the ambient fluid on either side of the plate outside the CS to be a passive gas. An axial electric field is applied either on one or both sides of a grounded plate. The equilibrium shapes of the CS and the electric potential in the surrounding gas are governed by an augmented Young-Laplace equation and the Laplace equation, respectively. These equations are solved computationally using the Galerkin finite element method. Results are shown as plots of dimensionless volume difference between the two droplets against electrical Bond number (ratio of electric to surface tension force). These phase diagrams are used to infer whether an electric field represents an effective means for toggling a CS.

Sambath, Krishnaraj; Basaran, Osman

2010-11-01

269

Immunoglobulin class switch DNA recombination: induction, targeting and beyond  

PubMed Central

Class switch DNA recombination (CSR) of the immunoglobulin heavy chain (IgH) locus is central to the maturation of the antibody response and critically requires the AID cytidine deaminase. CSR entails changes of the chromatin state and transcriptional activation of the IgH locus upstream and downstream switch (S) regions that are to undergo S-S DNA recombination, induction of AID, and targeting of CSR factors to S regions by 14-3-3 adaptors and as enabled by the transcription machinery and histone modifications. In this Review, we focus on recent advances in CSR induction and targeting. We also outline an integrated model of the assembly of macromolecular complexes that transduce critical epigenetic information to enzymatic effectors of the CSR machinery. PMID:22728528

Xu, Zhenming; Zan, Hong; Pone, Egest J.; Mai, Thach; Casali, Paolo

2012-01-01

270

Testing results for the HCT-1400 switch  

SciTech Connect

The High Current Thyristor (HCT)-1400 was characterized for switching performance. This is a Soviet switching device that has recently become available to the U.S. community. Substantial claims have been made regarding the performance of this switch. In particular, the switch was claimed to be able to switch high currents, with very short risetime without any significant jitter. This is an independent evaluation of the high current thyristor.

Hoeberling, R.F.; Wheeler, R.B.

1996-07-01

271

All-optical switching in a highly efficient parametric fiber mixer: design study.  

PubMed

Ultrafast all-optical switching in a highly nonlinear fiber with a longitudinally varied zero-dispersion wavelength was investigated theoretically and experimentally. We describe fiber-matched methodology for construction of a fast, low energy photon switch. The design relies on static and dynamic models and allows performance target selection, under constraints of physical fiber characteristic. The new design methodology was used to construct one-pump switch in the highly efficient parametric mixer. We demonstrate that such a parametric gate can operate at 100 GHz rate, with 2 aJ control energy, while achieving better than 50% extinction ratio. Theoretical analysis and experimental measurements indicate that accurate mapping of the fiber local dispersion is critical in optimizing the bandwidth and control energy of the switch. Switching performance limits are discussed and means for impairment mitigation are described. PMID:25321820

Pejkic, Ana; Nissim, Ron R; Myslivets, Evgeny; Wiberg, Andreas O J; Alic, Nikola; Radic, Stojan

2014-09-22

272

Carrier type dependence on spatial asymmetry of unipolar resistive switching of metal oxides  

NASA Astrophysics Data System (ADS)

We report a carrier type dependence on the spatial asymmetry of unipolar resistive switching for various metal oxides, including NiOx, CoOx, TiO2-x, YSZ, and SnO2-x. n-type oxides show a unipolar resistive switching at the anode side whereas p-type oxides switch at the cathode side. During the forming process, the electrical conduction path of p-type oxides extends from the anode to cathode while that of n-type oxides forms from the cathode to anode. The carrier type of switching oxide layer critically determines the spatial inhomogeneity of unipolar resistive switching during the forming process possibly triggered via the oxygen ion drift.

Nagashima, Kazuki; Yanagida, Takeshi; Kanai, Masaki; Celano, Umberto; Rahong, Sakon; Meng, Gang; Zhuge, Fuwei; He, Yong; Ho Park, Bae; Kawai, Tomoji

2013-10-01

273

Integration-dependent bacteriophage immunity provides insights into the evolution of genetic switches.  

PubMed

Genetic switches are critical components of developmental circuits. Because temperate bacteriophages are vastly abundant and greatly diverse, they are rich resources for understanding the mechanisms and evolution of switches and the molecular control of genetic circuitry. Here, we describe a new class of small, compact, and simple switches that use site-specific recombination as the key decision point. The phage attachment site attP is located within the phage repressor gene such that chromosomal integration results in removal of a C-terminal tag that destabilizes the virally encoded form of the repressor. Integration thus not only confers prophage stability but also is a requirement for lysogenic establishment. The variety of these self-contained integration-dependent immunity systems in different genomic contexts suggests that these represent ancestral states in switch evolution from which more-complex switches have evolved. They also provide a powerful toolkit for building synthetic biological circuits. PMID:23246436

Broussard, Gregory W; Oldfield, Lauren M; Villanueva, Valerie M; Lunt, Bryce L; Shine, Emilee E; Hatfull, Graham F

2013-01-24

274

Laser controlled optical switching in semiconductors  

SciTech Connect

A method and apparatus for switching an infrared radiation signal laser beam in which a semiconductor, capable of transmitting the signal beam without damage, is provided and upon which the signal beam is incident at an angle which may preferably be brewster's angle. The surface of the semiconductor is irradiated by a second laser beam which has a sufficiently high frequency to produce free carriers in the semiconductor and which has a sufficient radiation intensity and time duration to produce a free carrier density greater than the critical density for the signal beam resulting in substantially total reflection of the signal beam from the semiconductor surface. In particular, a pulsed CO/sub 2/ laser beam which is incident on a polycrystalline n-type germanium semiconductor is reflected by irradiating the semiconductor with a pulsed ruby or Nd:glass laser beam.

Alcock, A.; Corkum, P.B.; James, D.J.

1980-02-26

275

Critical Careers.  

ERIC Educational Resources Information Center

Reports the critical shortage of qualified equipment technicians, especially in biomedical equipment. Cites the importance of encouraging careers in this field and describes a source of occupational information. (SK)

Bowles, Roger A.

2001-01-01

276

Critical Patriotism.  

ERIC Educational Resources Information Center

Asserts that, post 9-11, responsibility to critical thought complicates simple-minded notions of loyalty and patriotism, and that "classics" of Western thought persist as touchstones of self-reflection and reason. (EV)

Euben, J. Peter

2002-01-01

277

Switching Behaviors and its Dynamics of a Co/Pt Nanodot Under the Assistance of rf Fields  

NASA Astrophysics Data System (ADS)

We have studied the switching behavior of a single Co/Pt multilayer dot under the assistance of rf fields. The switching field monotonically decreases with increasing rf frequency up to a critical frequency. It is found that the reduction of the switching field is more significant than the theoretical prediction based on the single macrospin model. In addition, switching field distribution due to thermal fluctuation is also considerably suppressed. The simulation has revealed that these drastic changes are caused by excitation of large amplitude spin waves in the dot.

Okamoto, Satoshi; Kikuchi, Nobuaki; Furuta, Masaki; Kitakami, Osamu; Shimatsu, Takehito

2012-12-01

278

Spin-transfer switching current distribution and reduction in magnetic tunneling junction-based structures  

Microsoft Academic Search

Spin transfer switching current distribution within a cell and switching current reduction were studied at room temperature for magnetic tunnel junction-based structures with resistance area product (RA) ranged from 10 to 30 ?-?m2 and TMR of 15%-30%. These were patterned into current perpendicular to plane configured nanopillars having elliptical cross sections of area ?0.02 ?m2. The width of the critical

Yiming Huai; Mahendra Pakala; Zhitao Diao; Yunfei Ding

2005-01-01

279

Power and Cost Reduction by Hybrid Optical Packet Switching with Shared Memory Buffering  

Microsoft Academic Search

The power consumption of a network becomes a critical performance metric for a petabit-per-second scale Internet, in addition to the system cost. We investigate the power and cost efficiency of all-optical and electrical technologies to understand the design principle for petabit-scale hybrid optical switch nodes for optical packet and burst switching. In order to achieve an efficient hybrid design, we

June-Koo Kevin Rhee; Chan-Kyun Lee; Ji-Hwan Kim; Yong-Hyub Won; Jin Seek Choi; JungYul Choi

2011-01-01

280

High power solid state switches  

NASA Astrophysics Data System (ADS)

We have successfully produced an optically triggered thyristor based in Gallium Arsenide, developed a model for breakdown, and are developing two related devices, including a Gallium Arsenide based static inductor thyristor. We are getting at the basic limitations of Gallium Arsenide for these applications, and are developing models for the physical processes that will determine device limitations. The previously supported gas phase work - resulting in the back-lighted thyratron (BLT) - has actually resulted in a very changed view of how switching can be accomplished, and this is impacting the design of important machines. The BLT is being studied internationally: in Japan for laser fusion and laser isotope separation. ITT has built a BLT that has switched 30 kA at 60 kV in testing at NSWC Dahlgren and the device is being commercialized by another American company. Versions of the switch are now being tested for excimer laser and other applications. Basically, the switch, which arose from pulse power physics studies at USC, can switch more current faster (higher di/dt), with less housekeeping, and with other advantageous properties. There are a large number of other new applications, include kinetic energy weapons, pulsed microwave sources and R.F. accelerators.

Gundersen, Martin

1991-11-01

281

Optimized Switch Allocation to Improve the Restoration Energy in Distribution Systems  

NASA Astrophysics Data System (ADS)

In distribution networks switching devices play critical role in energy restoration and improving reliability indices. This paper presents a novel objective function to optimally allocate switches in electric power distribution systems. Identifying the optimized location of the switches is a nonlinear programming problem (NLP). In the proposed objective function a new auxiliary function is used to simplify the calculation of the objective function. The output of the auxiliary function is binary. The genetic algorithm (GA) optimization method is used to solve this optimization problem. The proposed method is applied to a real distribution network and the results reveal that the method is successful.

Dezaki, Hamed H.; Abyaneh, Hossein A.; Agheli, Ali; Mazlumi, Kazem

2012-01-01

282

Binary switching in a 'symmetric' potential landscape  

PubMed Central

A binary switch is the basic building block for information processing. The potential energy profile of a bistable binary switch is a ‘symmetric' double well. The traditional method of switching it from one state (one well) to the other is to tilt the profile towards the desired state. Here, we present a case, where no such tilting is necessary to switch successfully, even in the presence of thermal noise. This happens because of the built-in dynamics inside the switch itself. It differs from the general perception on binary switching that in a ‘symmetric' potential landscape, the switching probability is 50% in the presence of thermal noise. Our results, considering the complete three-dimensional potential landscape, demonstrate intriguing phenomena on binary switching mechanism. With experimentally feasible parameters, we theoretically demonstrate such intriguing possibility in electric field induced magnetization switching of a shape-anisotropic single-domain magnetostrictive nanomagnet with two stable states at room-temperature. PMID:24154561

Roy, Kuntal; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

2013-01-01

283

Domain dynamics during ferroelectric switching.  

PubMed

The utility of ferroelectric materials stems from the ability to nucleate and move polarized domains using an electric field. To understand the mechanisms of polarization switching, structural characterization at the nanoscale is required. We used aberration-corrected transmission electron microscopy to follow the kinetics and dynamics of ferroelectric switching at millisecond temporal and subangstrom spatial resolution in an epitaxial bilayer of an antiferromagnetic ferroelectric (BiFeO(3)) on a ferromagnetic electrode (La(0.7)Sr(0.3)MnO(3)). We observed localized nucleation events at the electrode interface, domain wall pinning on point defects, and the formation of ferroelectric domains localized to the ferroelectric and ferromagnetic interface. These results show how defects and interfaces impede full ferroelectric switching of a thin film. PMID:22096196

Nelson, Christopher T; Gao, Peng; Jokisaari, Jacob R; Heikes, Colin; Adamo, Carolina; Melville, Alexander; Baek, Seung-Hyub; Folkman, Chad M; Winchester, Benjamin; Gu, Yijia; Liu, Yuanming; Zhang, Kui; Wang, Enge; Li, Jiangyu; Chen, Long-Qing; Eom, Chang-Beom; Schlom, Darrell G; Pan, Xiaoqing

2011-11-18

284

One temperature step away from the critical point  

Microsoft Academic Search

The disappearance of a wide range of critical fluctuations following a sudden temperature step away from the critical point is investigated theoretically. The step switches off the strong interaction on length scales larger than the final state correlation radius. This results in a nonequilibrium free field with fluctuations much larger than those in the final equilibrium state. In the course

Alexander Z. Patashinski

1996-01-01

285

Molecular DNA switches and DNA chips  

NASA Astrophysics Data System (ADS)

We present an assay to detect single-nucleotide polymorphisms on a chip using molecular DNA switches and isothermal rolling- circle amplification. The basic principle behind the switch is an allele-specific oligonucleotide circularization, mediated by DNA ligase. A DNA switch is closed when perfect hybridization between the probe oligonucleotide and target DNA allows ligase to covalently circularize the probe. Mismatches around the ligation site prevent probe circularization, resulting in an open switch. DNA polymerase is then used to preferentially amplify the closed switches, via rolling-circle amplification. The stringency of the molecular switches yields 102 - 103 fold discrimination between matched and mismatched sequences.

Sabanayagam, Chandran R.; Berkey, Cristin; Lavi, Uri; Cantor, Charles R.; Smith, Cassandra L.

1999-06-01

286

An efficient multi-channel wireless switching system  

E-print Network

service in packet- switching networks,” Proceedings of thepacket communication in multi-channel wireless switching networks.packet scheduling strategy for wireless networks,” High Perfor- mance Switching

Shim, Jaewook

2010-01-01

287

A piezoelectric cryogenic heat switch  

NASA Astrophysics Data System (ADS)

We have measured the thermal conductance of a mechanical heat switch actuated by a piezoelectric positioner, the PZHS (PieZo electric Heat Switch), at cryogenic temperatures. The thermal conductance of the PZHS was measured between 4 K and 10 K, and on/off conductance ratios of about 100-200 at lowest and highest measures temperature were achieved when the positioner applied its maximum force of 8 N, respectively. We discuss the advantages of using this system in cryogenic applications, and estimate the ultimate performance of an ideal PZHS.

Jahromi, Amir E.; Sullivan, Dan F.

2014-06-01

288

A piezoelectric cryogenic heat switch.  

PubMed

We have measured the thermal conductance of a mechanical heat switch actuated by a piezoelectric positioner, the PZHS (PieZo electric Heat Switch), at cryogenic temperatures. The thermal conductance of the PZHS was measured between 4 K and 10 K, and on/off conductance ratios of about 100-200 at lowest and highest measures temperature were achieved when the positioner applied its maximum force of 8 N, respectively. We discuss the advantages of using this system in cryogenic applications, and estimate the ultimate performance of an ideal PZHS. PMID:24985863

Jahromi, Amir E; Sullivan, Dan F

2014-06-01

289

Ad Critic  

NSDL National Science Digital Library

Ad Critic strives to enter every television advertisement into its database of online commercials, which can be downloaded for free and viewed with QuickTime. A complete list of advertisements is indexed by company and by ad title. There are, however, also indexes of newly added ads, most-downloaded ads, movie trailers, and music found in ads, making it easier for users to search for a new or favorite advertisement. Ad Critic includes a section on advertising news and commentary and provides services for advertising agencies including online market research and detailed viewer statistics.

290

Critical depletion.  

PubMed

Depletion interactions and the critical Casimir effect are usually regarded as distinct phenomena in colloidal suspensions. By experimentally investigating how the Asakura-Oosawa picture, appropriate for a weakly correlated depletant, is modified when critical correlations develop within the depletion agent, we conversely show that the former merges continuously into the latter, leading to a distinctive scaling behavior solely dictated by the depletant correlation length. A model based on density functional theory provides a microscopic understanding of the phenomenon and properly accounts for the observed trends. PMID:21231200

Buzzaccaro, Stefano; Colombo, Jader; Parola, Alberto; Piazza, Roberto

2010-11-01

291

Laser-activated optical bubble switch element  

Microsoft Academic Search

In Agilent's photonic switching platform, resistive heaters control tiny bubbles enabling all-optical switching. This paper reports on the addition of more efficient laser-activated heaters. Measurements confirm improvements in power dissipation and insertion loss stability.

Stephan Hengstler; John J. Uebbing; Patrick McGuire

2003-01-01

292

Ultrafast Beam Switching Using Coupled VCSELs  

NASA Technical Reports Server (NTRS)

We propose a new approach to performing ultrafast beam switching using two coupled Vertical-Cavity Surface-Emitting Lasers (VCSELs). The strategy is demonstrated by numerical simulation, showing a beam switching of 10 deg at 42 GHz.

Ning, Cun-Zheng; Goorjian, Peter

2001-01-01

293

Solar array switching power management  

NASA Technical Reports Server (NTRS)

Solar array power switching concepts are explored for a 250 kWe manned LEO platform, a 50-250 kWe load for an orbit transfer vehicle (OTV), and an unmanned platform with a 50 kWe load in GEO. A solar array switching power management (SASPM) system is under study to satisfy the switching demands. Direct connections to arrays would be implemented for voltage regulations, power distribution, and the capability of reconfiguring the arrays to meet requirements. Mission characteristics that would require the power sources were explored. The LEO platform was projected to use a concentrator, have no reconfigurability, use 250 NiH2 batteries, supply 80-0 Vdc to an ion drive, and have a 20-30 yr life. Both GEO and OTV arrays were planar, would feature reconfigurability, and supply 800 Vdc to an ion drive. NiH2 batteries would be on the OTV, while the GEO spacecraft would use AgH2 cells. A block diagram of the basic switching configuration is presented.

Cassinelli, J. E.; Smith, L. D.; Valgora, M.

1982-01-01

294

Remotely-actuated biomedical switch  

NASA Technical Reports Server (NTRS)

Remotely-actuated biomedical switching circuit using transistors consumes no power in the off position and can be actuated by a single-frequency telemetry pulse to control implanted instrumentation. Silicon controlled rectifiers permit the circuit design which imposes zero drain on supply batteries when not in use.

Lee, R. D.

1969-01-01

295

Switching in High Vacuum Enviroment  

Microsoft Academic Search

An analysis is made of the properties and problems of Maximum current interrupting ability and photos of contacts contacts, switching, and holding off high and low voltages, high which are interrupting up to 18,000 a are shown. and low currents ac, dc, and RF in a high vacuum environment with some relation to outer space problems. Characteristics of contacts from

H. Ross

1963-01-01

296

Fast all-optical switch  

NASA Technical Reports Server (NTRS)

An apparatus and method wherein polarization rotation in alkali vapors or other mediums is used for all-optical switching and digital logic and where the rate of operation is proportional to the amplitude of the pump field. High rates of speed are accomplished by Rabi flopping of the atomic states using a continuously operating monochromatic atomic beam as the pump.

Shay, Thomas M. (Inventor); Poliakov, Evgeni Y. (Inventor); Hazzard, David A. (Inventor)

2001-01-01

297

A Scaffold Makes the Switch  

NSDL National Science Digital Library

Protein kinase cascades are a reoccurring feature of signal transduction pathways. Recent investigations have focused on how kinase-scaffolding proteins help to convert a graded stimulus into a switch-like or binary response. New findings reveal that the graded-to-binary conversion can be turned on or off, depending on the location of the scaffold within the cell.

Henrik G. Dohlman (Chapel Hill;University of North Carolina REV)

2008-10-21

298

Fast microwave switching power divider  

NASA Technical Reports Server (NTRS)

Unit divides power from single input among any 12 of 120 output terminals and redistributes it in 6 microseconds. Microwave current from coaxial line excites disk feeding many radial strip transmission lines. Built for use in electronically-steered S-band antenna, device also divides and switches energy among filters and phase shifters.

Johnson, R. W.; Stockton, R. J.

1981-01-01

299

Tag-switching architecture: overview  

Microsoft Academic Search

Tag switching is a way to combine the label-swapping forwarding paradigm with network layer routing. This has several advantages. Tags can have a wide spectrum of forwarding granularities, so at one end of the spectrum a tag could be associated with a group of desti-nations, while at the other a tag could be associated with a single application flow. At

Yakov Rekhter; B. Davie; E. Rosen; G. Swallow; D. Farinacci; D. Katz

1997-01-01

300

High voltage MOSFET switching circuit  

DOEpatents

The problem of source lead inductance in a MOSFET switching circuit is compensated for by adding an inductor to the gate circuit. The gate circuit inductor produces an inductive spike which counters the source lead inductive drop to produce a rectangular drive voltage waveform at the internal gate-source terminals of the MOSFET. 2 figs.

McEwan, T.E.

1994-07-26

301

High voltage MOSFET switching circuit  

DOEpatents

The problem of source lead inductance in a MOSFET switching circuit is compensated for by adding an inductor to the gate circuit. The gate circuit inductor produces an inductive spike which counters the source lead inductive drop to produce a rectangular drive voltage waveform at the internal gate-source terminals of the MOSFET.

McEwan, Thomas E. (Livermore, CA)

1994-01-01

302

Anode initiated surface flashover switch  

DOEpatents

A high voltage surface flashover switch has a pair of electrodes spaced by an insulator. A high voltage is applied to an anode, which is smaller than the opposing, grounded, cathode. When a controllable source of electrons near the cathode is energized, the electrons are attracted to the anode where they reflect to the insulator and initiate anode to cathode breakdown.

Brainard, John P. (Albuquerque, NM); Koss, Robert J. (Albuquerque, NM)

2003-04-29

303

Buffering in optical packet switches  

Microsoft Academic Search

This paper consists of a categorization of optical buffering strategies for optical packet switches, and a comparison of the performance of these strategies both with respect to packet loss\\/delay and bit error rate (BER) performance. Issues surrounding optical buffer implementation are discussed, and representative architectures are introduced under different categories. Conclusions are drawn about packet loss and BER performance, and

David K. Hunter; Meow C. Chia; Ivan Andonovic

1998-01-01

304

Critical Load  

NSDL National Science Digital Library

In this activity, learners explore the concepts of structural engineering and how to measure the critical load, or the maximum weight a structure can bear. Learners investigate basic structures, how to reinforce, materials selection, and working as a team, design and build a prototype structure to hold increasingly greater weights.

Ieee

2014-05-22

305

Spark gap switch with spiral gas flow  

DOEpatents

A spark gap switch having a contaminate removal system using an injected gas. An annular plate concentric with an electrode of the switch defines flow paths for the injected gas which form a strong spiral flow of the gas in the housing which is effective to remove contaminates from the switch surfaces. The gas along with the contaminates is exhausted from the housing through one of the ends of the switch.

Brucker, John P. (Espanola, NM)

1989-01-01

306

Energy loss in spark gap switches  

NASA Astrophysics Data System (ADS)

The paper reports on numerical study of the energy loss in spark gap switches. The operation of the switches is analyzed using the Braginsky model which allows calculation of the time dependence of the spark channel resistance. The Braginsky equation is solved simultaneously with generator circuit equations for different load types. Based on the numerical solutions, expressions which determine both the energy released in a spark gap switch and the switching time are derived.

Oreshkin, V. I.; Lavrinovich, I. V.

2014-04-01

307

A zero-current-switching PWM flyback converter with a simple auxiliary switch  

Microsoft Academic Search

A simple and effective approach of turning an isolated hard-switched converter design into a soft-switched one is presented. By adding an auxiliary winding, switch and small capacitor to the conventional pulsewidth modulation (PWM) isolated flyback converter, all switches and diodes are softly turned on and off. No extra active or passive voltage clamp circuit is needed to suppress voltage stress

Henry Shu-Hung Chung; S. Y. R. Hui; Wei-Hua Wang

1999-01-01

308

Degree of Conversational Code-Switching Enhances Verbal Task Switching in Cantonese-English Bilinguals  

ERIC Educational Resources Information Center

The study examined individual differences in code-switching to determine the relationship between code-switching frequency and performance in verbal and non-verbal task switching. Seventy-eight Cantonese-English bilinguals completed a semi-structured conversation to quantify natural code-switching, a verbal fluency task requiring language…

Yim, Odilia; Bialystok, Ellen

2012-01-01

309

Comparison of switching devices in scalable switch concept for medium voltage medium frequency power conversion  

Microsoft Academic Search

This paper provides a comparison of switch concepts for medium frequency (MF) medium voltage (MV) applications in the lower power range (> 1 kHz). The comparison is based on measurements of actual discrete switches for hard-switched and ZVS forward topologies. It is shown that standard low power IGBTs in a scalable switch can be used to obtain the lowest losses

Jochen Mast; Guntram Scheible; Henry Gueldner

2001-01-01

310

BER Performance in Wavelength Packet Switched WDM systems during Nano-second Wavelength Switching Events  

E-print Network

. This effect may ultimately influence the design of WDM wavelength packet- switched networks employing transmitter, as the overall design of the wavelength packet-switched WDM networks will be heavily dependentBER Performance in Wavelength Packet Switched WDM systems during Nano-second Wavelength Switching

311

Task Set Formation: Switching to a Completely Novel Task Enhances Task Switching Costs  

E-print Network

Task Set Formation: Switching to a Completely Novel Task Enhances Task Switching Costs Michael W from general task switching. Further, it is unclear how high-level task set formation processes a unique task set formation process, and that it would be reflected in enhanced task switching costs

312

49 CFR 218.103 - Hand-operated switches, including crossover switches.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Hand-operated switches, including crossover...Switches, and Fixed Derails § 218.103 Hand-operated switches, including crossover...operating or verifying the position of a hand-operated switch shall: (1)...

2011-10-01

313

49 CFR 218.103 - Hand-operated switches, including crossover switches.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Hand-operated switches, including crossover...Switches, and Fixed Derails § 218.103 Hand-operated switches, including crossover...operating or verifying the position of a hand-operated switch shall: (1)...

2010-10-01

314

49 CFR 218.103 - Hand-operated switches, including crossover switches.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Hand-operated switches, including crossover...Switches, and Fixed Derails § 218.103 Hand-operated switches, including crossover...operating or verifying the position of a hand-operated switch shall: (1)...

2013-10-01

315

49 CFR 218.103 - Hand-operated switches, including crossover switches.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Hand-operated switches, including crossover...Switches, and Fixed Derails § 218.103 Hand-operated switches, including crossover...operating or verifying the position of a hand-operated switch shall: (1)...

2012-10-01

316

BER Performance in Wavelength Packet Switched WDM systems during Nano-second Wavelength Switching Events  

E-print Network

BER Performance in Wavelength Packet Switched WDM systems during Nano-second Wavelength Switching of another WDM signal during fast wavelength switching events. A nano-second tuneable laser is switched across the monitored channel to perform the study. Introduction The migration from single wavelength SDH

317

Structural Constraints in Code-Switched Advertising  

Microsoft Academic Search

Code switching, the use of mixed-language expressions, is gaining prominence in advertising targeting linguistic minorities. Two studies investigate the existence of linguistic rules governing the use of code switching and identify situations in which those rules have a greater impact on persuasion. The studies extend Myers-Scotton's 1995 model of code switching by revealing an interaction between linguistic correctness and type

David Luna; Dawn Lerman

2005-01-01

318

Switch for serial or parallel communication networks  

DOEpatents

A communication switch apparatus and a method for use in a geographically extensive serial, parallel or hybrid communication network linking a multi-processor or parallel processing system has a very low software processing overhead in order to accommodate random burst of high density data. Associated with each processor is a communication switch. A data source and a data destination, a sensor suite or robot for example, may also be associated with a switch. The configuration of the switches in the network are coordinated through a master processor node and depends on the operational phase of the multi-processor network: data acquisition, data processing, and data exchange. The master processor node passes information on the state to be assumed by each switch to the processor node associated with the switch. The processor node then operates a series of multi-state switches internal to each communication switch. The communication switch does not parse and interpret communication protocol and message routing information. During a data acquisition phase, the communication switch couples sensors producing data to the processor node associated with the switch, to a downlink destination on the communications network, or to both. It also may couple an uplink data source to its processor node. During the data exchange phase, the switch couples its processor node or an uplink data source to a downlink destination (which may include a processor node or a robot), or couples an uplink source to its processor node and its processor node to a downlink destination. 9 figs.

Crosette, D.B.

1994-07-19

319

Algorithmic aspects of high speed switching  

E-print Network

A major drawback of the traditional output queuing technique is that it requires a switch speedup of N, where N is the size of the switch. This dependence on N makes the switch non-scalable at high speeds. Input queuing ...

Mneimneh, Saadeddine S

2002-01-01

320

Packet Scheduling with Switch Conguration Delays  

Microsoft Academic Search

In modern packet switches, technology limitations may introduce switch cong- uration delays that are non-negligible compared with the time required to transmit a single packet. In this paper, we propose a methodology for scheduling of packets, in the context of these technology limitations. If the total tolerable delay through a packet switch is at least on the order of the

R. L. Cruz; Saleh Al-Harthi

321

Switch for serial or parallel communication networks  

DOEpatents

A communication switch apparatus and a method for use in a geographically extensive serial, parallel or hybrid communication network linking a multi-processor or parallel processing system has a very low software processing overhead in order to accommodate random burst of high density data. Associated with each processor is a communication switch. A data source and a data destination, a sensor suite or robot for example, may also be associated with a switch. The configuration of the switches in the network are coordinated through a master processor node and depends on the operational phase of the multi-processor network: data acquisition, data processing, and data exchange. The master processor node passes information on the state to be assumed by each switch to the processor node associated with the switch. The processor node then operates a series of multi-state switches internal to each communication switch. The communication switch does not parse and interpret communication protocol and message routing information. During a data acquisition phase, the communication switch couples sensors producing data to the processor node associated with the switch, to a downlink destination on the communications network, or to both. It also may couple an uplink data source to its processor node. During the data exchange phase, the switch couples its processor node or an uplink data source to a downlink destination (which may include a processor node or a robot), or couples an uplink source to its processor node and its processor node to a downlink destination.

Crosette, Dario B. (DeSoto, TX)

1994-01-01

322

Voluntary Task Switching: Chasing the Elusive Homunculus  

ERIC Educational Resources Information Center

In the voluntary task switching procedure, subjects choose the task to perform on a series of bivalent stimuli, requiring top-down control of task switching. Experiments 1-3 contrasted voluntary task switching and explicit task cuing. Choice behavior showed small, inconsistent effects of external stimulus characteristics, supporting the assumption…

Arrington, Catherine M.; Logan, Gordon D.

2005-01-01

323

Components of Attentional Set-switching  

Microsoft Academic Search

A series of distinct event-related potentials (ERPs) have been recorded from the scalp of human subjects as they switch from one task to another. It is possible that task switching may depend on different mechanisms depending on whether the switch requires a change in attentional set, in other words the redirecting of attention to different aspects of a sensory stimulus,

M. F. S. Rushworth; R. E. Passingham; A. C. Nobre

2005-01-01

324

A Bilingual Advantage in Task Switching  

ERIC Educational Resources Information Center

This study investigated the possibility that lifelong bilingualism may lead to enhanced efficiency in the ability to shift between mental sets. We compared the performance of monolingual and fluent bilingual college students in a task-switching paradigm. Bilinguals incurred reduced switching costs in the task-switching paradigm when compared with…

Prior, Anat; MacWhinney, Brian

2010-01-01

325

Optimal control of switched autonomous linear systems  

Microsoft Academic Search

The paper deals with the optimal control of switched piecewise linear autonomous systems, where the objective is that of minimizing a quadratic performance index over an infinite time horizon. We assume that the switching sequence and the corresponding jump matrix sequence is known, while the unknown switching times are the optimization parameters. The optimal control for this class of systems,

Alessandro Giua; Carla Seatzu; Cornelis Van Der Mee

2001-01-01

326

Programmable Switch for Shared Bus Replacement  

Microsoft Academic Search

A switching interconnection architecture with programmable priorities is described. The switch has been designed to replace shared buses in order to increase bandwidth in the local clusters of large systems-on-chip. The design features guaranteed service for the highest priority input port and best effort service for the rest. Suitable standard cell switch fabrics are discussed and their implementations compared. A

T. Ahonen; J. Nurmi

2006-01-01

327

A CW Gunn Diode Switching Element.  

ERIC Educational Resources Information Center

As part of a study of the application of communication satellites to educational development, certain technical aspects of such a system were examined. A current controlled bistable switching element using a CW Gunn diode is reported on here. With modest circuits switching rates of the order of 10 MHz have been obtained. Switching is initiated by…

Hurtado, Marco; Rosenbaum, Fred J.

328

Quality-switched laser tattoo removal.  

PubMed

Quality-switched (Q-switched) laser is the most effective method to remove tattoos with minimal adverse outcomes. This article reviews the types of tattoos commonly treated with Q-switched lasers, mechanisms behind the procedure, technologies used, patient considerations and contraindications, addressing patient expectations, treatment procedures, possible adverse reactions, and future techniques and technology. PMID:24853159

Williams, Nkaya

2014-06-01

329

Critical Information at Critical Moments  

ERIC Educational Resources Information Center

On a daily basis, administrators are reminded of the potential, perhaps the likelihood, of violence or natural crises on their campuses. Comprehensive studies have been conducted and point to recommendations and best practices for planning, preparing, responding to, and recovering from critical incidents. The International Association of Campus…

Fierman, Ben; Thrower, Raymond H., Jr.

2011-01-01

330

Suppression of subtelomeric VSG switching by Trypanosoma brucei TRF requires its TTAGGG repeat-binding activity  

PubMed Central

Trypanosoma brucei causes human African trypanosomiasis and regularly switches its major surface antigen, VSG, in the bloodstream of its mammalian host to evade the host immune response. VSGs are expressed exclusively from subtelomeric loci, and we have previously shown that telomere proteins TbTIF2 and TbRAP1 play important roles in VSG switching and VSG silencing regulation, respectively. We now discover that the telomere duplex DNA-binding factor, TbTRF, also plays a critical role in VSG switching regulation, as a transient depletion of TbTRF leads to significantly more VSG switching events. We solved the NMR structure of the DNA-binding Myb domain of TbTRF, which folds into a canonical helix-loop-helix structure that is conserved to the Myb domains of mammalian TRF proteins. The TbTRF Myb domain tolerates well the bulky J base in T. brucei telomere DNA, and the DNA-binding affinity of TbTRF is not affected by the presence of J both in vitro and in vivo. In addition, we find that point mutations in TbTRF Myb that significantly reduced its in vivo telomere DNA-binding affinity also led to significantly increased VSG switching frequencies, indicating that the telomere DNA-binding activity is critical for TbTRF's role in VSG switching regulation. PMID:25313155

Jehi, Sanaa E.; Li, Xiaohua; Sandhu, Ranjodh; Ye, Fei; Benmerzouga, Imaan; Zhang, Mingjie; Zhao, Yanxiang; Li, Bibo

2014-01-01

331

Secure videoconferencing equipment switching system and method  

DOEpatents

A switching system and method are provided to facilitate use of videoconference facilities over a plurality of security levels. The system includes a switch coupled to a plurality of codecs and communication networks. Audio/Visual peripheral components are connected to the switch. The switch couples control and data signals between the Audio/Visual peripheral components and one but nor both of the plurality of codecs. The switch additionally couples communication networks of the appropriate security level to each of the codecs. In this manner, a videoconferencing facility is provided for use on both secure and non-secure networks.

Hansen, Michael E. (Livermore, CA)

2009-01-13

332

Energy storage, compression, and switching. Vol. 2  

SciTech Connect

This book is a compilation of papers presented at the Second International Conference on Energy Storage, Compression, and Switching, which was held in order to assemble active researchers with a major interest in plasma physics, electron beams, electric and magnetic energy storage systems, high voltage and high current switches, free-electron lasers, and pellet implosion plasma focus. Topics covered include: Slow systems: 50-60 Hz machinery, homopolar generators, slow capacitors, inductors, and solid state switches; Intermediate systems: fast capacitor banks; superconducting storage and switching; gas, vacuum, and dielectric switching; nonlinear (magnetic) switching; imploding liners capacitors; explosive generators; and fuses; and Fast systems: Marx, Blumlein, oil, water, and pressurized water dielectrics; switches; magnetic insulation; electron beams; and plasmas.

Nardi, V.; Bostick, W.H.; Sahlin, H.

1983-01-01

333

High power ferrite microwave switch  

NASA Technical Reports Server (NTRS)

A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out short-slot 3 db quadrature coupler, a dual driver electronic circuit, and input logic interface circuitry. The basic mode of operation of the high power ferrite microwave switch is identical to that of a four-port, differential phase shift, switchable circulator. By appropriately designing the phase shifters and electronic driver circuits to operate in the flux-transfer magnetization mode, power and temperature insensitive operation was achieved. A list of the realized characteristics of the developed units is given.

Bardash, I.; Roschak, N. K.

1975-01-01

334

Synthetic ferrimagnets with thermomagnetic switching  

NASA Astrophysics Data System (ADS)

Interlayer exchange coupling in strong/weak/strong ferromagnetic multilayers is investigated as a function of external magnetic field and temperature, with the focus on the magnetization switching near the Curie transition in the spacer composed of a diluted ferromagnet of concentration paramagnetic in the bulk. The effect of an externally applied reversing magnetic field on the width of the thermomagnetic transition is studied experimentally and explained theoretically as a result of the interplay between the proximity-induced exchange and the Zeeman effects in the system. Of high potential for applications should be the ability to switch one of the ferromagnetic outer layers using magnetic field, temperature, or a combination of the two.

Kravets, A. F.; Dzhezherya, Yu. I.; Tovstolytkin, A. I.; Kozak, I. M.; Gryshchuk, A.; Savina, Yu. O.; Pashchenko, V. A.; Gnatchenko, S. L.; Koop, B.; Korenivski, V.

2014-09-01

335

High frequency switching battery charger  

SciTech Connect

A power supply is described for charging a storage battery which consists of: power supply means adapted to be connected to a source of electrical energy for supply power; rectifying means operatively connected to the power supply means for rectifying the supplied power; output transformer means operatively connected to the rectifying means and to the battery for transforming the rectified power; power switching means operatively connected to the output transformer means for controlling a flow of current from the rectifying means through the output transformer means; pulse width modulator means operatively connected to the power switching means for controlling the power switching means, with a coupling transformer interposed between the pulse width modulator means and the power switching means; current sensing means for sensing the flow of current through the output transformer means; current limiting means responsive to the current sensing means and operatively connected to the pulse width modulator means for controlling the pulse width modulator means; charging voltage control means responsive to the current sensing means and operatively connected to the pulse width modulator means for controlling the pulse width modulator means; latch means for stopping the pulse width modulator means operatively connected to the pulse width modulator means; overcurrent sensing means responsive to the current sensing means operatively connected to the latch means for controlling the latch means; means for sensing the absense of the storage battery operatively connected to the latch means for controlling the latch means; and end-of-charge sensing means operatively connected to a terminal of the battery and to the latch means for controlling the latch means responsive to a predetermined voltage present at the terminal.

Kaminski, H.

1986-04-22

336

Switch for Good Community Program  

SciTech Connect

Switch4Good is an energy-savings program that helps residents reduce consumption from behavior changes; it was co-developed by Balfour Beatty Military Housing Management (BB) and WattzOn in Phase I of this grant. The program was offered at 11 Navy bases. Three customer engagement strategies were evaluated, and it was found that Digital Nudges (a combination of monthly consumption statements with frequent messaging via text or email) was most cost-effective.

Crawford, Tabitha; Amran, Martha

2013-11-19

337

Efficiency consideration of DC link soft-switching inverters for motor drive applications  

NASA Astrophysics Data System (ADS)

?his paper critically evaluates efficiency of soft switching inverters including an actively clamped resonant DC link inverter and a clamped-mode resonant pole inverter. An analytical approach to evaluating efficiency of the clamped-mode soft switching inverter has been developed. The evaluation results are compared with that of the standard pulse-width-modulation (PWM) inverter. A 50-kW induction motor is used as the variable load, and the inverter efficiency is evaluated under different speed and torque conditions. The clamped-mode soft-switching inverter, although eliminating the switching loss, shows poor efficiency over the entire load range. Under low load conditions, the efficiency profile is even worse. The actively clamped resonant DC link inverter shows highest efficiency over the entire speed and torque range. However, its energy saving over the standard PWM inverter is marginal under full load or high speed conditions.

Lai, J. S.; Young, R. W.; McKeever, J. W.

338

Two-terminal nanoelectromechanical bistable switches based on molybdenum-sulfur-iodine molecular wire bundles  

NASA Astrophysics Data System (ADS)

We demonstrate the application of Mo6S3I6 molecular wire bundles for electrically controllable two-terminal on-off switches. We investigate how changes in the contact electrode material and geometry influence the device characteristics, hysteretic switching behavior and device stability. We also determine the device operating parameters, particularly the Young's moduli (40-270 GPa), operating current densities (3.2 × 105-7 × 106 A m - 2) and force constants. Although qualitatively, the properties of Mo6S3I6 nanowires in nanoelectromechanical (NEM) switches are similar to those of carbon nanotubes (CNTs), their lower friction coefficient, higher mechanical stability and higher operation voltages give specific advantages in terms of smaller differences in on-off operating potentials, higher switching speeds and lower energy consumption than CNTs, which are critical for applications in NEM devices.

Andzane, J.; Prikulis, J.; Dvorsek, D.; Mihailovic, D.; Erts, D.

2010-03-01

339

Revealing the role of defects in ferroelectric switching with atomic resolution.  

PubMed

Ferroelectric materials are characterized by a spontaneous polarization, which can be reoriented with an applied electric field. The switching between polarized domains is mediated by nanoscale defects. Understanding the role of defects in ferroelectric switching is critical for practical applications such as non-volatile memories. This is especially the case for ferroelectric nanostructures and thin films in which the entire switching volume is proximate to a defective surface. Here we report the nanoscale ferroelectric switching of a tetragonal PbZr(0.2)Ti(0.8)O(3) thin film under an applied electric field using in situ transmission electron microscopy. We found that the intrinsic electric fields formed at ferroelectric/electrode interfaces determine the nucleation sites and growth rates of ferroelectric domains and the orientation and mobility of domain walls, whereas dislocations exert a weak pinning force on domain wall motion. PMID:22186887

Gao, Peng; Nelson, Christopher T; Jokisaari, Jacob R; Baek, Seung-Hyub; Bark, Chung Wung; Zhang, Yi; Wang, Enge; Schlom, Darrell G; Eom, Chang-Beom; Pan, Xiaoqing

2011-01-01

340

Novel Resistance Switching Devices Based on Sub-10 nm Polymer Thin Film  

NASA Astrophysics Data System (ADS)

Resistive switching memory devices were fabricated using ultrathin (<10 nm) poly(o-anthranilic acid-co-aniline) films. When the devices were biased beyond a critical value with a current compliance of 10 mA, the devices suddenly switched from a high resistive state to a low resistive state (10 mA), with a difference in injection current of more than 4 orders of magnitude. Controlling the injection current level (by controlling the current compliance) allowed the high resistive state of the device to be restored. The devices possess a prolonged retention time of 3 ×103 s after switching. The conduction mechanism in the OFF-state implies that the resistive switching of the device can be explained in terms of filament theory.

Lee, Dongjin; Baek, Sungsik; Ree, Moonhor; Kim, Ohyun

2008-07-01

341

H? control for switched fuzzy systems via dynamic output feedback: Hybrid and switched approaches  

NASA Astrophysics Data System (ADS)

Fuzzy T-S model has been proven to be a practical and effective way to deal with the analysis and synthesis problems for complex nonlinear systems. As for switched nonlinear system, describing its subsystems as fuzzy T-S models, namely switched fuzzy system, naturally is an alternative method to conventional control approaches. In this paper, the H? control problem for a class of switched fuzzy systems is addressed. Hybrid and switched design approaches are proposed with different availability of switching signal information at switching instant. The hybrid control strategy includes two parts: fuzzy controllers for subsystems and state updating controller at switching instant, and the switched control strategy contains the controllers for subsystems. It is demonstrated that the conservativeness is reduced by introducing the state updating behavior but its cost is an online prediction of switching signal. Numerical examples are given to illustrate the effectiveness of proposed approaches and compare the conservativeness of two approaches.

Xiang, Weiming; Xiao, Jian; Iqbal, Muhammad Naveed

2013-06-01

342

Critical points of adsorbed phases using a 2D lattice gas equation of state  

Microsoft Academic Search

The types of critical phase diagrams for adsorbed binary mixtures that can be predicted by an equation of state (EOS) based on a two-dimensional lattice gas theory are investigated. The search for critical point conditions was done using the Hicks and Young algorithm, switching to the Heidemann and Khalil algorithm in the close of vicinity of a critical point. We

Marcelo F. Alfradique; Papa M. Ndiaye; Marcelo Castier

2006-01-01

343

Optically-switched submillimeter-wave oscillator and radiator having a switch-to-switch propagation delay  

NASA Technical Reports Server (NTRS)

A submillimeter wave-generating integrated circuit includes an array of N photoconductive switches biased across a common voltage source and an optical path difference from a common optical pulse of repetition rate f sub 0 providing a different optical delay to each of the switches. In one embodiment, each incoming pulse is applied to successive ones of the N switches with successive delays. The N switches are spaced apart with a suitable switch-to-switch spacing so as to generate at the output load or antenna radiation of a submillimeter wave frequency f on the order of N f sub 0. Preferably, the optical pulse has a repetition rate of at least 10 GHz and N is of the order of 100, so that the circuit generates radiation of frequency of the order of or greater than 1 Terahertz.

Spencer, Michael G. (inventor); Maserjian, Joseph (inventor)

1995-01-01

344

A novel accelerometer tilt switch device for switch actuation in the patient with profound disability.  

PubMed

We describe the design and operation of a new switch that can be operated by patients with severely limited movement. The basis for the switch is an inexpensive single-chip accelerometer device. The switch responds to a relatively rapid rotation of the active components. We have ensured that the sensitivity of the switch device is adjustable over a wide range. The device automatically adjusts for changes in attitude of the device that result from a patient changing posture. We show that the device can operate in a wide range of attitudes. We describe 2 case studies in which the switch was successfully used as a head tilt switch. PMID:12808551

Perring, Stephen; Summers, Anthony; Jones, Emma L; Bowen, Frances J; Hart, Katharine

2003-06-01

345

Finite Ground Coplanar Waveguide Shunt MEMS Switches for Switched Line Phase Shifters  

NASA Technical Reports Server (NTRS)

Switches with low insertion loss and high isolation are required for switched line phase shifters and the transmit/receive switch at the front end of communication systems. A Finite Ground Coplanar (FGC) waveguide capacitive, shunt MEMS switch has been implemented on high resistivity Si. The switch has demonstrated an insertion loss of less than 0.3 dB and a return loss greater than 15 dB from 10 to 20, GHz. The switch design, fabrication, and characteristics are presented.

Ponchak, George E.; Simons, Rainee N.; Scardelletti, Maximillian; Varaljay, Nicholas C.

2000-01-01

346

COMMENTS AND CRITICISM COMMENTS AND CRITICISM  

E-print Network

COMMENTS AND CRITICISM COMMENTS AND CRITICISM MEASURING CONFIRMATION AND EVIDENCE2' ayesian In a recent paper, David Christensen3 criticizes these measures, and as a partial solution to the criticisms is a positive relevance measure. Christensen's criticisms of the standard measures focus mainly

Fitelson, Branden

347

Intrinsic single-domain switching in ferroelectric materials on a nearly ideal surface  

E-print Network

Intrinsic single-domain switching in ferroelectric materials on a nearly ideal surface S. V, TN, October 2, 2007 (received for review July 6, 2007) Ferroelectric domain nucleation and growth the decoupled Green function theory by using tip geometry determined from the domain wall profile. The critical

Chen, Long-Qing

348

Intrinsic Nucleation Mechanism and Disorder Effects in Polarization Switching on Ferroelectric Surfaces  

E-print Network

2009) The temperature dependence of ferroelectric domain nucleation in epitaxial films of BiFeO3-dimensional ferroelectrics, the polar- ization domain nucleation in confined geometries that approach the size of the critical nucleus, and the compara- tive role of domain nucleation and domain-wall motion in the switching

Chen, Long-Qing

349

Detection of Impulsive Effects in Switched DAEs with Applications to Power Electronics Reliability Analysis  

E-print Network

Detection of Impulsive Effects in Switched DAEs with Applications to Power Electronics Reliability-tolerant power electronics systems to identify design flaws that could jeopardize its reliability. The system-critical systems, e.g., shipboard, aircraft, and automotive, where electrical power provided by power electronics

Trenn, Stephan

350

Switched steerable multiple beam antenna system  

NASA Technical Reports Server (NTRS)

A steerable multibeam five element cross-feed cluster antenna system is described. The feed power is divided into five branches. Each branch includes a switching network comprised of a plurality of time delay elements each individually controlled by a respective electromagnetic latching switch. Frequency independent individual two-dimensional beam steering at intermediate (IF) scanning frequencies is thereby provided wherein discrete incremental time delays are introduced by the switching networks into each branch and the signals recombined thereafter to form each beam. The electromagnetic latched switching reduces power consumption and permits higher power switching and reciprocal coincident tranmsit and receive operation. Frequency independence due to incremental time delay switching permits coincident reciprocal operation and steering for transmit-receive signal paths carrying different transmit-receive frequencies. Diagonal quarter wave plates in the waveguides alter polarization from the circular to orthogonal linear to provide transmitter-receiver isolation.

Iwasaki, Richard S. (inventor)

1988-01-01

351

Dynamically reconfigurable optical packet switch (DROPS).  

PubMed

A novel Dynamically Reconfigurable Optical Packet Switch (DROPS) that combines both spectral and spatial switching capabilities is proposed and experimentally demonstrated for the first time. Compared with an Arrayed Waveguide Grating Router (AWGR), the added spatial switching capability provided by the microelectromechanical systems (MEMS) enables dynamically reconfigurable routing that is not possible with an AWGR alone. This methodology has several advantages over an AWGR including scalability, additional degrees of freedom in routing a packet from an ingress port to an egress port and more flexibility in path or line card recovery. The experimental demonstration implemented with 10-Gb/s packets shows that the added spatial switching does not degrade the bit-error-rate performance, indicating the promising potential of DROPS as a versatile and ultra-high capacity switch for optical packet-switched networks. PMID:19529627

Huang, Chi-Heng; Chou, Hsu-Feng; Bowers, John E; Toudeh-Fallah, Farzam; Gyurek, Russ

2006-12-11

352

Ferroelectric liquid crystal optical interconnect switching systems  

NASA Astrophysics Data System (ADS)

This grant explored the possible use of ferroelectric liquid crystals (FLC's) in the reamization of photonic switching fabrics. Problems addressed included device fabrication, switch architectures, and switch performance. Experimental versions of most architectures were constructed. The aim of the contract was to develop techniques for using ferroelectric liquid crystals (FLC's) for novel photonic switching architectures. Initial work was devoted to mastering the technology of making FLC polarization rotation shutters, which formed the basis for the switching architecture work to follow. Much of this work was performed using the facilities of Stanford's Center for Integrated Systems. We were able to build such shutters with respectable properties, including reasonable uniformity, insertion losses of the order X dB, and extinction ratios of the order of Y db. Switching speeds observed were on the order of ZZZ. Having mastered the basic shutter technology, we moved on to employing such shutters in novel architectures.

Goodman, Joseph W.

1993-02-01

353

Switched steerable multiple beam antenna system  

NASA Astrophysics Data System (ADS)

A steerable multibeam five element cross-feed cluster antenna system is described. The feed power is divided into five branches. Each branch includes a switching network comprised of a plurality of time delay elements each individually controlled by a respective electromagnetic latching switch. Frequency independent individual two-dimensional beam steering at intermediate (IF) scanning frequencies is thereby provided wherein discrete incremental time delays are introduced by the switching networks into each branch and the signals recombined thereafter to form each beam. The electromagnetic latched switching reduces power consumption and permits higher power switching and reciprocal coincident tranmsit and receive operation. Frequency independence due to incremental time delay switching permits coincident reciprocal operation and steering for transmit-receive signal paths carrying different transmit-receive frequencies. Diagonal quarter wave plates in the waveguides alter polarization from the circular to orthogonal linear to provide transmitter-receiver isolation.

Iwasaki, Richard S.

1988-09-01

354

Pulse switching for high energy lasers  

NASA Technical Reports Server (NTRS)

A saturable inductor switch for compressing the width and sharpening the rise time of high voltage pulses from a relatively slow rise time, high voltage generator to an electric discharge gas laser (EDGL) also provides a capability for efficient energy transfer from a high impedance primary source to an intermediate low impedance laser discharge network. The switch is positioned with respect to a capacitive storage device, such as a coaxial cable, so that when a charge build-up in the storage device reaches a predetermined level, saturation of the switch inductor releases or switches energy stored in the capactive storage device to the EDGL. Cascaded saturable inductor switches for providing output pulses having rise times of less than ten nanoseconds and a technique for magnetically biasing the saturable inductor switch are disclosed.

Laudenslager, J. B.; Pacala, T. J. (inventors)

1981-01-01

355

MEMS switches having non-metallic crossbeams  

NASA Technical Reports Server (NTRS)

A RF MEMS switch comprising a crossbeam of SiC, supported by at least one leg above a substrate and above a plurality of transmission lines forming a CPW. Bias is provided by at least one layer of metal disposed on a top surface of the SiC crossbeam, such as a layer of chromium followed by a layer of gold, and extending beyond the switch to a biasing pad on the substrate. The switch utilizes stress and conductivity-controlled non-metallic thin cantilevers or bridges, thereby improving the RF characteristics and operational reliability of the switch. The switch can be fabricated with conventional silicon integrated circuit (IC) processing techniques. The design of the switch is very versatile and can be implemented in many transmission line mediums.

Scardelletti, Maximillian C (Inventor)

2009-01-01

356

TILBW Bipolar Power Switching Transistor  

NASA Astrophysics Data System (ADS)

The work reports the development of TILBW (Two Interdigitation Levels with heavily-doped Base Wells) bipolar power switching transistors, which combine the main advantages of both TIL and GAT devices. The TILBW transistors exhibit the following many-fold advantages in comparison with identical, yet conventional devices of the same class (identical area and case) processed simultaneously: a reduction of the turn-on time by a factor of ˜ 20; a two-fold reduction of the fall time tf; an ˜ 18-percent increase of VCEO(SUS); an ˜ 23-percent increase of VCBO; an enhanced RBSOA.

Silard, Andrei P.; Nani, Gabriel

1989-03-01

357

Laser-triggered vacuum switch  

DOEpatents

A laser-triggered vacuum switch has a material such as a alkali metal halide on the cathode electrode for thermally activated field emission of electrons and ions upon interaction with a laser beam, the material being in contact with the cathode with a surface facing the discharge gap. The material is preferably a mixture of KCl and Ti powders. The laser may either shine directly on the material, preferably through a hole in the anode, or be directed to the material over a fiber optic cable.

Brannon, Paul J. (Albuquerque, NM); Cowgill, Donald F. (Danville, CA)

1990-01-01

358

Cobra communications switch integration program  

NASA Technical Reports Server (NTRS)

The paper describes a design modification to reduce the visual and manual workload associated with the radio selection and communications tasks in the U.S. Army AH-1 Cobra helicopter. The modification involves the integration of the radio selection and microphone actuating tasks into a single operation controlled by the transmit-intercom switch. Ground-based and flight tests were conducted to evaluate the modified configuration during twelve flight tasks. The results show that the proposed configuration performs twice as fast as the original configuration.

Shively, Robert J.; Haworth, Loran A.; Szoboszlay, Zoltan; Murray, F. Gerald

1989-01-01

359

Microwave-triggered laser switch  

DOEpatents

A high-repetition rate switch for delivering short duration, high-power electrical pulses from a pulsed-charged dc power supply. The present invention utilizes a microwave-generating device such as a magnetron that is capable of producing high-power pulses at high-pulse repetition rates and fast-pulse risetimes for long periods with high reliability. The rail-gap electrodes provide a large surface area that reduces induction effects and minimizes electrode erosion. Additionally, breakdown is initiated in a continuous geometric fashion that also increases operating lifetime of the device.

Piltch, Martin S. (Los Alamos, NM)

1984-01-01

360

Microwave-triggered laser switch  

DOEpatents

A high-repetition rate switch is described for delivering short duration, high-powered electrical pulses from a pulsed-charged dc power supply. The present invention utilizes a microwave-generating device such as a magnetron that is capable of producing high-power pulses at high-pulse repetition rates and fast-pulse risetimes for long periods with high reliability. The rail-gap electrodes provide a large surface area that reduces induction effects and minimizes electrode erosion. Additionally, breakdown is initiated in a continuous geometric fashion that also increases operating lifetime of the device.

Piltch, M.S.

1982-05-19

361

A new switched power linac structure  

SciTech Connect

A new pulse power structure has been described that utilizes an easily accessible rectilinear switch. The new structure is more ''forgiving'' (as far as risetime is concerned) than the radial line transformer, and contains fewer switching structures/unit length. The combination of the new structure with the switch proposed seems to offer interesting possibilities for a future linear collider. 13 refs., 6 figs., 2 tabs.

Villa, F.

1989-03-01

362

Caffeine improves anticipatory processes in task switching  

Microsoft Academic Search

We studied the effects of moderate amounts of caffeine on task switching and task maintenance using mixed-task (AABB) blocks, in which participants alternated predictably between two tasks, and single-task (AAAA, BBBB) blocks. Switch costs refer to longer reaction times (RT) on task switch trials (e.g. AB) compared to task-repeat trials (e.g. BB); mixing costs refer to longer RTs in task-repeat

Zoë Tieges; Jan Snel; Albert Kok; Jasper G. Wijnen; Monicque M. Lorist; K. Richard Ridderinkhof

2006-01-01

363

An Overview of Optical Label Switching Technology  

NASA Astrophysics Data System (ADS)

Optical label switching is a new technology of optical switching, which can overcome the electronic bottleneck of optical communication effectively, optical label switching (OLS) network as a specific implementation of future optical packet network has been paid more and more attention, its key technology is the generation and extraction of optical label. In this paper, subcarrier multiplexing label, OCDM optical code label and orthogonal modulation label are described and discussed. Their strength and weakness are analyzed.

Su, Fugen; Jin, Hongli; Jin, Fulu

364

Switching Optical Packets -Motivation and Prospects  

E-print Network

node (1) · Complexity reduction · Scalability improvement before after F·W F Taps F·W - Delay Lines (Tunable) - F Delay Lines (Fixed) F 2·F WDM Demultiplexers F·W F·W Receivers (Fixed) F·W F Transmitters (Fixed) F·W - 2x1 Couplers F F WDM Multiplexers W - FxF Switches - W (F-1)x(F-1) Switches Switch Control

Wichmann, Felix

365

Electro-optic Q-switch  

NASA Technical Reports Server (NTRS)

An electro-optic Q-switch for generating sequence of laser pulses was disclosed. The Q-switch comprises a quadratic electro-optic material and is connected with an electronic unit generating a radio frequency wave with positive and negative pulses alternatively. The Q-switch is controlled by the radio frequency wave in such a way that laser pulse is generated when the radio frequency wave changes its polarity.

Zou, Yingyin (Inventor); Chen, Qiushui (Inventor); Zhang, Run (Inventor); Jiang, Hua (Inventor)

2006-01-01

366

Diamond switches for high temperature electronics  

SciTech Connect

This paper presents the results of switching voltages of 500 V and currents of 10 A using chemical vapor deposited (CVD) diamond as a switching material. The switching is performed by using an electron beam that penetrates the diamond, creates electron hole pairs, and lowers its resistivity to about 20 {Omega}-cm and its resistance to about 4 {Omega}. Tests were performed at room temperature but in a configuration that allows for 250 C.

Loubriel, G.M.; Zutavern, F.J.; Ruebush, M.H. [and others

1997-06-01

367

Prospective pulsed power applications of pseudospark switches  

Microsoft Academic Search

In this paper, results of comparative tests of commercially available TDI model pseudospark switches (PSS, also known as: cold cathode thyratrons, copper vapor & low pressure switches) versus mercury type D ignitron switches in Field Reversed Configuration (FRC) installations with energy storage up to 14 kJ, operating voltage 5-40 kV, peak currents Imax =190 kA, jitter 4-10 ns are presented.

J. Slough; C. Pihl; V. D. Bochkov; D. V. Bochkov; P. V. Panov; I. N. Gnedin

2009-01-01

368

The effects of para-chloromercuribenzoic acid and different oxidative and sulfhydryl agents on a novel, non-AT1, non-AT2 angiotensin binding site identified as neurolysin.  

PubMed

A novel, non-AT1, non-AT2 brain binding site for angiotensin peptides that is unmasked by p-chloromercuribenzoate (PCMB) has been identified as a membrane associated variant of neurolysin. The ability of different organic and inorganic oxidative and sulfhydryl reactive agents to unmask or inhibit 125I-Sar1Ile8 angiotensin II (SI-Ang II) binding to this site was presently examined. In tissue membranes from homogenates of rat brain and testis incubated in assay buffer containing losartan (10 ?M) and PD123319 (10 ?M) plus 100 ?M PCMB, 5 of the 39 compounds tested inhibited 125I-SI Ang II binding in brain and testis. Mersalyl acid, mercuric chloride (HgCl2) and silver nitrate (AgNO3) most potently inhibited 125I-SI Ang II binding with IC50s ~1-20 ?M. This HgCl2 inhibition was independent of any interaction of HgCl2 with angiotensin II (Ang II) based on the lack of effect of HgCl2 on the dipsogenic effects of intracerebroventricularly administered Ang II and 125I-SI Ang II binding to AT1 receptors in the liver. Among sulfhydryl reagents, cysteamine and reduced glutathione (GSH), but not oxidized glutathione (GSSG) up to 1mM, inhibited PCMB-unmasked 125I-SI Ang II binding in brain and testis. Thimerosal and 4-hydroxymercuribenzoate moderately inhibited PCMB-unmasked 125I-SI Ang II binding in brain and testis at 100 ?M; however, they also unmasked non-AT1, non-AT2 binding independent of PCMB. 4-Hydroxybenzoic acid did not promote 125 I-SI Ang II binding to this binding site indicating that only specific organomercurial compounds can unmask the binding site. The common denominator for all of these interacting substances is the ability to bind to protein cysteine sulfur. Comparison of cysteines between neurolysin and the closely related enzyme thimet oligopeptidase revealed an unconserved cysteine (cys650, based on the full length variant) in the proposed ligand binding channel (Brown et al., 2001) [45] near the active site of neurolysin. It is proposed that the mercuric ion in PCMB and closely related organomercurial compounds binds to cys650, while the acidic anion forms an ionic bond with a nearby arginine or lysine along the channel to effect a conformational change in neurolysin that promotes Ang II binding. PMID:23511333

Santos, Kira L; Vento, Megan A; Wright, John W; Speth, Robert C

2013-06-10

369

An Accurate, Low-Voltage, CMOS Switching Power Supply With Adaptive On-Time Pulse-Frequency Modulation (PFM) Control  

Microsoft Academic Search

Integrated switching power supplies with multimode control are gaining popularity in state-of-the-art portable applications like cellular phones, personal digital assistants (PDAs), etc., because of their ability to adapt to various loading conditions and therefore achieve high efficiency over a wide load-current range, which is critical for extended battery life. Constant-frequency, pulsewidth modulated (PWM) switching converters, for instance, have poor light-load

Biranchinath Sahu; Gabriel A. Rincón-Mora

2007-01-01

370

Spin Transfer Magnetization Switching Read\\/Write Cycle Test in MgO-Based Magnetic Tunnel Junctions  

Microsoft Academic Search

We present the results of spin transfer torque magnetization switching results for some MgO-based magnetic tunnel junctions (MTJ) with tunneling magnetoresistance (TMR) ratios of 38.6% to 200% and critical current densities of 1.032 times 107 A\\/cm2 down to 1.68 times 106 A\\/cm2. We observed 2.2 times 104 stable read\\/write (R\\/W) cycles before failure under the spin transfer torque magnetization switching.

J. M. Lee; L. X. Ye; M. C. Weng; Y. C. Chen; S. C. Li; J. P. Su; Te-ho Wu

2007-01-01

371

Voltage-impulse-induced non-volatile ferroelastic switching of ferromagnetic resonance for reconfigurable magnetoelectric microwave devices.  

PubMed

A critical challenge in realizing magnetoelectrics based on reconfigurable microwave devices, which is the ability to switch between distinct ferromagnetic resonances (FMR) in a stable, reversible and energy efficient manner, has been addressed. In particular, a voltage-impulse-induced two-step ferroelastic switching pathway can be used to in situ manipulate the magnetic anisotropy and enable non-volatile FMR tuning in FeCoB/PMN-PT (011) multiferroic heterostructures. PMID:23857709

Liu, Ming; Howe, Brandon M; Grazulis, Lawrence; Mahalingam, Krishnamurthy; Nan, Tianxiang; Sun, Nian X; Brown, Gail J

2013-09-20

372

All optical switching in henna thin film  

NASA Astrophysics Data System (ADS)

The optical nonlinearity in henna (Lawson (2- hydroxyl-1,4 naphthoquinone) film was utilized to demonstrate all optical switching. The nonlinear absorption of the henna film was calculated by measuring the transmission of the laser beam ( ? = 488 nm) as a function of incident light intensities. The observed nonlinear absorption is attributed to a two-photon absorption process. The pump and probe technique was used to demonstrate all optical switching. The switching characteristics can be utilized to generate all-optical logic gates such as simple inverter switches (NOT) NOR, AND NAND logic functions.

Henari, Fryad Z.; Jasim, Khalil E.

2013-08-01

373

Magnetic switch coupling to synchronize magnetic modulators  

DOEpatents

Apparatus for synchronizing the output pulses from a pair of magnetic switches is disclosed. An electrically conductive loop is provided between the pair of switches with the loop having windings about the core of each of the magnetic switches. The magnetic coupling created by the loop removes voltage and timing variations between the outputs of the two magnetic switches caused by any of a variety of factors. The only remaining variation is a very small fixed timing offset caused by the geometry and length of the loop itself. 13 figs.

Reed, K.W.; Kiekel, P.

1999-04-27

374

Magnetic switch coupling to synchronize magnetic modulators  

DOEpatents

Apparatus for synchronizing the output pulses from a pair of magnetic switches. An electrically conductive loop is provided between the pair of switches with the loop having windlings about the core of each of the magnetic switches. The magnetic coupling created by the loop removes voltage and timing variations between the outputs of the two magnetic switches caused by any of a variety of factors. The only remaining variation is a very small fixed timing offset caused by the geometry and length of the loop itself.

Reed, Kim W. (Albuquerque, NM); Kiekel, Paul (Albuquerque, NM)

1999-01-01

375

High-index-contrast electromechanical optical switches  

E-print Network

System developers are looking to replace protocol-dependent, bandwidth-limited optical networks with intelligent optically-transparent integrated photonic networks. Several electromechanical optical switches are explored ...

Bryant, Reginald (Reginald Eugene), 1978-

2011-01-01

376

Fixing DNA breaks during class switch recombination  

PubMed Central

Immunoglobulin (Ig) class switch recombination (CSR) involves the breakage and subsequent repair of two DNA sequences, known as switch (S) regions, which flank IgH constant region exons. The resolution of CSR-associated breaks is thought to require the nonhomologous end-joining (NHEJ) DNA repair pathway, but the role of the NHEJ factor DNA-dependent protein kinase catalytic subunit (DNA-PKcs) in this process has been unclear. A new study, in which broken IgH-containing chromosomes in switching B cells were visualized directly, clearly demonstrated that DNA-PKcs and, unexpectedly, the nuclease Artemis are involved in the resolution of switch breaks. PMID:18332183

Jolly, Christopher J.; Cook, Adam J.L.; Manis, John P.

2008-01-01

377

Mechanism of conductance switching: An optical investigation  

NASA Astrophysics Data System (ADS)

Electronic conductance switching in devices based on thin films of an organic molecule has been studied. Switching between two conducting states has been induced by voltage pulse, while the states have been probed by optical and electrical measurements simultaneously. In situ optical measurements showed that electroreduction of molecules led to conductance switching and appearance of high-conducting state in the device. We could "write" or "erase" a state by applying electrical pulse and "read" it by measuring electronic absorbance and conductivity. The "write" and "read" processes have been carried out for many cycles to exhibit a correspondence between conductance switching and electrochromism.

Bandyopadhyay, Anirban; Chowdhury, Arabinda; Pal, Amlan J.

2006-09-01

378

Multi-megavolt low jitter multistage switch  

DOEpatents

It is one object of the present invention to provide a multistage switch capable of holding off numerous megavolts, until triggered, from a particle beam accelerator of the type used for inertial confinement fusion. The invention provides a multistage switch having low timing jitter and capable of producing multiple spark channels for spreading current over a wider area to reduce electrode damage and increase switch lifetime. The switch has fairly uniform electric fields and a short spark gap for laser triggering and is engineered to prevent insulator breakdowns.

Humphreys, D.R.; Penn, K.J. Jr.

1985-06-19

379

Electric field induced anisotropy modification in (Ga,Mn)As: A strategy for the precessional switching of the magnetization  

NASA Astrophysics Data System (ADS)

We propose a scheme for the precessional switching of the magnetization in the magnetic semiconductor (Ga,Mn)As using cubic anisotropy field reduction triggered by electric field and a small assisting magnetic field. We identify magnetic field regions for toggle switching and direct-overwrite of the magnetization and discuss the toggle switching critical curve dependence on the cubic anisotropy field decrease. We also determine the half-precession period of the magnetization and propose field conditions for magnetization trajectories which are optimally immune to external noise and damping.

Balestriere, P.; Devolder, T.; Wunderlich, J.; Chappert, C.

2010-04-01

380

Switching losses of IGBTs under zero-voltage and zero-current switching  

Microsoft Academic Search

Turn-off switching losses of punch-through (PT) and nonpunch-through (NPT) IGBTs under hard switching (HS) and zero-voltage switching (ZVS) are presented and evaluated at 25°C, 75°C and 125°C. A comparison between PT and NPT devices based on their internal device characteristics is given for HS and ZVS. The low emitter efficiency NPT IGBTs used in this paper have smaller switching losses

Ahmed Elasser; M. J. Schutten; V. Vlatkovic; David A. Torrey; M. H. Kheraluwala

1996-01-01

381

Task Switching Across the Life Span: Effects of Age on General and Specific Switch Costs  

Microsoft Academic Search

The authors investigated age-related changes in executive control using an Internet-based task-switching experiment with 5,271 participants between the ages of 10 and 66 years. Speeded face categorization was required on the basis of gender (G) or emotion (E) in single task blocks (GGG… and EEE…) or switching blocks (GGEEGGEE…). General switch costs, the difference between switching block and single task

Stian Reimers; Elizabeth A. Maylor

2005-01-01

382

Increased response switching, perseveration and perseverative switching following d -amphetamine in the rat  

Microsoft Academic Search

Four experiments examined the effects of d-amphetamine on response switching and perseveration in apparatus allowing a choice of response location. The relative ‘cost’ of a switch between two response locations and repetitive responding at a single location by rats was manipulated in the various test settings to provide baseline probabilities of switching. d-Amphetamine (0.2–2.3 mg\\/kg) increased response switching. This effect

J. L. Evenden; T. W. Robbins

1983-01-01

383

Enhancement of an Optical Burst Switch with Shared Electronic Buffers  

E-print Network

on the sustainable load. Index Terms--optical burst switching, optical packet switching, contention resolution. I considered [2], such as Optical Packet Switching (OPS) and Optical Burst Switching (OBS), recent studies under 0.2 for a target loss probability of 10-7 . Consequently, networks relying on all-optical switches

Paris-Sud XI, Université de

384

Sequential Effects in Deduction: Cost of Inference Switch  

ERIC Educational Resources Information Center

The task-switch paradigm has helped psychologists gain insight into the processes involved in changing from one activity to another. The literature has yielded consistent results about switch cost reconfiguration (abrupt offset in regular task-switch vs. gradual reduction in random task-switch; endogenous and exogenous components of switch cost;…

Milan, Emilio G.; Moreno-Rios, Sergio; Espino, Orlando; Santamaria, Carlos; Gonzalez-Hernandez, Antonio

2010-01-01

385

Ultrafast wavelength switching in bistable microlasers for optical memory applications  

Microsoft Academic Search

Bistability and ultrafast wavelength switching in coupled-cavity microlasers is investigated from the point of view of application in optical memory. Theoretical guidelines for optimizing the switching performance are drawn. A tradeoff between switching time and energy is found. Both these properties can be controlled by a proper choice of switching pulse parameters. At optimum, switching times of less than 10

Sergei V. Zhukovsky; Dmitry N. Chigrin

2009-01-01

386

A New Optical Switching Fabric Architecture Incorporating Rapidly Switching All-Optical Variable Delay Buffers  

E-print Network

.4250) Networks, (060.4510) Optical communications 1. Introduction Optical packet switching (OPS) [1] brings a new@ece.ucdavis.edu Abstract: This paper discusses new optical packet switch architectures utilizing all-optical variable delay and the optical layer. The OPS technology allows switching of packets directly in the optical domain, overcomes

Kolner, Brian H.

387

Top electrode material related bipolar memory and unipolar threshold resistance switching in amorphous Ta2O5 films  

NASA Astrophysics Data System (ADS)

Tantalum oxide (Ta2O5) is one of the most studied materials for its stable resistance switching and potential application in nonvolatile memory devices. Top electrode and essential switching material are two critical points dominating its switching characteristics. Here, Ta2O5 films of amorphous nature (a-Ta2O5) with tunable thicknesses were made by changing the applied voltage during anodic oxidation of Ta-metal foils. The resistance-switching behavior of an a-Ta2O5 film in a metal/a-Ta2O5/Ta configuration was investigated by using a sputtered W or Ag metal film as the top electrode. The unipolar threshold switching phenomenon was observed using W as top electrode (WTE), while bipolar switching behaviors were achieved using active Ag metal as top electrode (AgTE). The thickness of the a-Ta2O5 film shows an obvious effect on the SET voltage in a WTE/a-Ta2O5/Ta device. The interfacial redox reaction induced formation of more conductive Ta-rich suboxide and the Joule heating effect are proposed to contribute to the unipolar threshold switching behavior. It is also suggested that the bipolar switching could have resulted from the electrochemical reaction-induced dissolution and growth of Ag conducting channels inside the Ta2O5 films.

Cai, Yunyu; Sheng, Cuicui; Liang, Changhao

2013-06-01

388

Design of optimal switching surfaces for switched autonomous systems Axel Schild, Xu Ding, Magnus Egerstedt and Jan Lunze  

E-print Network

. Given a finite mode sequence, the control task requires to determine switching surfaces, whichDesign of optimal switching surfaces for switched autonomous systems Axel Schild, Xu Ding, Magnus for computing optimal switching surfaces, i.e. optimal feedback controllers for switched autonomous nonlin- ear

Egerstedt, Magnus

389

Task-set switching under cue-based versus memory-based switching conditions in younger and older adults  

Microsoft Academic Search

Adult age differences in task switching and advance preparation were examined by comparing cue-based and memory-based switching conditions. Task switching was assessed by determining two types of costs that occur at the general (mixing costs) and specific (switching costs) level of switching. Advance preparation was investigated by varying the time interval until the next task (short, middle, very long). Results

Jutta Kray

2006-01-01

390

COMMENTS AND CRITICISM 663 COMMENTS AND CRITICISM  

E-print Network

COMMENTS AND CRITICISM 663 COMMENTS AND CRITICISM MEASURING CONFIRMATION AND EVIDENCE* B ayesian of Philosophy, Inc. 664 THE JOURNAL OF PHILOSOPHY In a recent paper, David Christensen3 criticizes these measures, and as a partial solution to the criticisms he raises, suggests what he regards as an improved

Fitelson, Branden

391

Critical Pedagogy for Critical Mathematics Education  

ERIC Educational Resources Information Center

This article provides a brief introduction to critical pedagogy and further discussion on critical mathematics education. Critical mathematics education enables students to read the world with mathematics. Three emerging domains of mathematics education related to critical mathematics education are discussed in this manuscript: ethnomathematics,…

Tutak, Fatma Aslan; Bondy, Elizabeth; Adams, Thomasenia L.

2011-01-01

392

Ames Lab 101: Ultrafast Magnetic Switching  

SciTech Connect

Ames Laboratory physicists have found a new way to switch magnetism that is at least 1000 times faster than currently used in magnetic memory technologies. Magnetic switching is used to encode information in hard drives, magnetic random access memory and other computing devices. The discovery potentially opens the door to terahertz and faster memory speeds.

Jigang Wang

2013-04-08

393

Improved Two-Phase Switching Regulator  

NASA Technical Reports Server (NTRS)

Coupled-inductor polyphase regulator has better efficiency and lower inductor losses. Improved two-phase switching regulator employs negative coupling between inductors to achieve better power-to-weight ratio while reducing peak switching currents and inductor losses. Improvement of about 35 percent using new technique.

Rippel, W. E.

1984-01-01

394

Ames Lab 101: Ultrafast Magnetic Switching  

ScienceCinema

Ames Laboratory physicists have found a new way to switch magnetism that is at least 1000 times faster than currently used in magnetic memory technologies. Magnetic switching is used to encode information in hard drives, magnetic random access memory and other computing devices. The discovery potentially opens the door to terahertz and faster memory speeds.

Jigang Wang

2013-06-05

395

Differentiation-Induced Switching Costs and Poaching  

Microsoft Academic Search

We show that the presence of sufficiently significant switching costs, which are increasing in the degree of product differentiation, generates an equilibrium configuration with maximal differentiation within the framework of a Hotelling model with linear transportation costs. The equilibrium with maximal differentiation offers a formalization of the idea that competing firms have noncooperative incentives to establish maximal switching cost barriers.

Thomas Gehrig; Rune Stenbacka

2004-01-01

396

Stability of stochastic switched SIRS models  

NASA Astrophysics Data System (ADS)

Stochastic stability problems of a stochastic switched SIRS model with or without distributed time delay are considered. By utilizing the Lyapunov methods, sufficient stability conditions of the disease-free equilibrium are established. Stability conditions about the subsystem of the stochastic switched SIRS systems are also obtained.

Meng, Xiaoying; Liu, Xinzhi; Deng, Feiqi

2011-11-01

397

Morphological Priming Survives a Language Switch  

ERIC Educational Resources Information Center

In a long-lag morphological priming experiment, Dutch (L1)-English (L2) bilinguals were asked to name pictures and read aloud words. A design using non-switch blocks, consisting solely of Dutch stimuli, and switch-blocks, consisting of Dutch primes and targets with intervening English trials, was administered. Target picture naming was facilitated…

Verdonschot, Rinus G.; Middelburg, Renee; Lensink, Saskia E.; Schiller, Niels O.

2012-01-01

398

Proceedings of the switched power workshop  

SciTech Connect

These proceedings contain most of the presentations given at a workshop on the current state of research in techniques for switched power acceleration. The proceedings are divided, as was the workshop itself, into two parts. Part 1, contains the latest results from a number of groups active in switched power research. The major topic here is a method for switching externally supplied power onto a transmission line. Advocates for vacuum photodiode switching, solid state switching, gas switching, and synthetic pulse generation are all presented. Other important areas of research described in this section concern: external electrical and laser pulsing systems; the properties of the created electromagnetic pulse; structures used for transporting the electromagnetic pulse to the region where the electron beam is located; and possible applications. Part 2 of the proceedings considers the problem of designing a high brightness electron gun using switched power as the power source. This is an important first step in demonstrating the usefulness of switched power techniques for accelerator physics. In addition such a gun could have immediate practical importance for advanced acceleration studies since the brightness could exceed that of present sources by several orders of magnitude. I would like to take this opportunity to thank Kathleen Tuohy and Patricia Tuttle for their assistance in organizing and running the workshop. Their tireless efforts contribute greatly to a very productive meeting.

Fernow, R.C. (ed.)

1988-01-01

399

Language Switching in the Production of Phrases  

ERIC Educational Resources Information Center

The language switching task has provided a useful insight into how bilinguals produce language. So far, however, the studies using this method have been limited to lexical access. The present study provides empirical evidence on language switching in the production of simple grammar structures. In the reported experiment, Polish-English unbalanced…

Tarlowski, Andrzej; Wodniecka, Zofia; Marzecova, Anna

2013-01-01

400

Voice synchronization in packet switching networks  

Microsoft Academic Search

An algorithm for voice synchronization for packet switching networks is presented. The algorithm has been tested both in simulation and on a real network. The algorithm runs on the TRAME packet switching network for both the Vocoder and CELP DoD voice coding standards. Some results of these tests are presented. Some details of the algorithm development and implementation are given

Felipe Alvarez-Cuevas; Miquel Bertran; Francesc Oller; Josep M. Selga

1993-01-01

401

Connection principles for multipath, packet switching networks  

Microsoft Academic Search

Packet switched Multistage Interconnection Networks (MINs) have been mostly proposed to use unique connection path between any source and destination. We propose to add a few extra stages in an MIN to create multiple paths between any source and destination. Connection principles of Multipath MINs (MMINs) for packet switching are presented in this paper. Performance of such network is analyzed

Chi-Yuan Chin; Kai Hwang

1984-01-01

402

ERICA Switch Algorithm: A Complete Description  

Microsoft Academic Search

: The ERICA switch algorithm has been discussed extensively in TM group in the past. However, over the last two years, the algorithm has been substantially modified. This contribution describes the current version of ERICA switch algorithm in complete detail. The algorithm achieves both efficiency and fairness, and exhibits a fast transient response. The development of the algorithm is traced,

Raj Jain; Shiv Kalyanaraman; Rohit Goyal; Sonia Fahmy; Ram Viswanathan

1996-01-01

403

High-Performance Switched Reluctance Brushless Drives  

Microsoft Academic Search

Switched reluctance (SR) drives offer the advantages of simple and robust motor construction, high speeds, high overall efficiencies over a wide operating range of torque and speed, simple power converter circuits with a reduced number of switches, and excellent controllability. The basis of these claims is explained. The history of the SR system, in particular the extensive research at Nottingham

William F. Ray; Peter J. Lawrenson; Rex M. Davis; J. Michael Stephenson; Norman N. Fulton; Roy J. Blake

1986-01-01

404

Task Switching Effects in Anticipation Timing  

ERIC Educational Resources Information Center

To understand how task switching affects human performance, there is a need to investigate how it influences the performance of tasks other than those involving bivalent stimulus categorization. The purpose of this study, therefore, was to investigate the effects of task switching on anticipation timing performance, which typically requires…

Fairbrother, Jeffrey T.; Brueckner, Sebastian

2008-01-01

405

Technology advances in wideband packet switching  

Microsoft Academic Search

The authors examine some recent technology advances in the evolution of wideband packet technology (WPT). These advances include contention resolution in WPT switch fabrics, GaAs implementation of WPT switch fabric, and packet processing in trunk interfaces. It is concluded that WPT architectures are ideally suited for aggressive incorporation in advanced VLSI technology particularly for the implementation of the core of

A. K. Vaidya; M. A. Pashan

1988-01-01

406

Domain switching in polycrystalline ferroelectric ceramics  

E-print Network

of ferroelectricity using density functional theory6­8 , crystallographic and domain-wall structure using atomisticARTICLES Domain switching in polycrystalline ferroelectric ceramics J. Y. LI1, R. C. ROGAN2,3, E electrical or mechanical loads. Domain switching is important in technological exploitation of ferroelectric

Li, Jiangyu

407

Radio-controlled, sound-operated switch  

NASA Technical Reports Server (NTRS)

Switch presently provides remote control switching, by radio signals, or pollution sampling devices. Can be used for remote weather station interrogation, firing of pyrotechnics, control of dangerous equipment, or control of device in location where it is impractical to run metallic conductors because of time limitations, distance, or terrain.

Bryant, T. D.; Soloman, D. W., Jr.

1974-01-01

408

Assessing the Consequences of a Channel Switch  

Microsoft Academic Search

Switching marketing channels is an expensive and sticky decision. While a number of theories suggest efficiency and strategic differences between channels, there is virtually no work on combining these ideas into an empirically workable methodology to assess the impact of a channel switch. In this study, we undertake to close this gap with an empirical study of the sports drink

George John; Om Narasimhan

2008-01-01

409

Gas mixtures for spark gap closing switches  

DOEpatents

Gas mixtures for use in spark gap closing switches comprised of fluorocarbons and low molecular weight, inert buffer gases. To this can be added a third gas having a low ionization potential relative to the buffer gas. The gas mixtures presented possess properties that optimized the efficiency spark gap closing switches. 6 figs.

Christophorou, L.G.; McCorkle, D.L.; Hunter, S.R.

1987-02-20

410

"DISTINGUISHABILITY" OF SWITCHING SYSTEMS FOR DIAGNOSIS  

E-print Network

"DISTINGUISHABILITY" OF SWITCHING SYSTEMS FOR DIAGNOSIS E. A. Domlan, J. Ragot, D. Maquin Centre de.inpl-nancy.fr Abstract This article tackles the problem of the diagnosis of switching systems. These systems can be controlled or not. If the operating conditions are unknown, the diagnosis of such systems

Paris-Sud XI, Université de

411

Automatic Monitoring of Switching Power Supplies  

NASA Technical Reports Server (NTRS)

Fast analysis of switching waveforms allows detection of impending failures. Switching power conditioner converts dc power from source such as battery or solar cell array to well regulated dc at convenient voltages and currents. Concept originally developed for space stations and spacecraft also suitable for power conditioning equipment in aircraft and in terrestrial photovoltaic power systems.

Moser, R. L.

1985-01-01

412

Magnetic switch for reactor control rod  

Microsoft Academic Search

A magnetic reed switch assembly for activating an electromagnetic grapple utilized to hold a control rod in position above a reactor core. In normal operation the magnetic field of a permanent magnet is short-circuited by a magnetic shunt, diverting the magnetic field away from the reed switch. The magnetic shunt is made of a material having a Curie-point at the

Germer; John H

1986-01-01

413

Magnetic switch for reactor control rod. [LMFBR  

Microsoft Academic Search

A magnetic reed switch assembly is described for activating an electromagnetic grapple utilized to hold a control rod in position above a reactor core. In normal operation the magnetic field of a permanent magnet is short-circuited by a magnetic shunt, diverting the magnetic field away from the reed switch. The magnetic shunt is made of a material having a Curie-point

Germer

1982-01-01

414

Ultrafast Directional Beam Switching in Coupled VCSELs  

NASA Technical Reports Server (NTRS)

We propose a new approach to performing ultrafast directional beam switching using two coupled Vertical-Cavity Surface-Emitting Lasers (VCSELs). The proposed strategy is demonstrated for two VCSELs of 5.6 microns in diameter placed about 1 micron apart from the edges, showing a switching speed of 42 GHz with a maximum far-field angle span of about 10 degrees.

Ning, Cun-Zheng; Goorjian, Peter

2001-01-01

415

Children's Code Switching in Group Conversations.  

ERIC Educational Resources Information Center

There is a growing tendency to accept that schools can teach the concept of code switching in language awareness programs, and this has been done in Denmark, to an extent, for a decade or so. This research studied code switching as an interpersonal power tool in two minority children who participated in a longitudinal study of the bilingual…

Jorgensen, J. N.

416

A Switching Surge Transient Recording Device  

Microsoft Academic Search

A switching surge transient recording device has been designed, built, and tested which serves as a continuous, unattended monitor of power system switching transients. Rather than reproduce the transient waveform, the recorder senses and records the positive and negative peak magnitudes of the transient to within a 4.0 per unit overvoltage limit, the maximum positive and maximum negative rates of

Dean Perry; Richard Raupach; C. A. E. Uhlig

1968-01-01

417

Al-doped ZnO as a switching layer for transparent bipolar resistive switching memory  

NASA Astrophysics Data System (ADS)

In this report, we employ an Al-doped ZnO (AZO) layer as a resistive switching layer for transparent resistive switching random access memory devices. An Indium-Tin-Oxide (ITO)/AZO/ITO/glass device exhibits a transmittance of ˜80% (including a glass substrate) in the visible wavelength region and demonstrates reliable bipolar resistive switching behavior over d.c. 300 sweeping cycles with a low operation voltage and a very low variation in the switching threshold voltage. These results indicate that the AZO film is a promising transparent resistive switching layer.

Yu, Hyeongwoo; Kim, Minho; Kim, Yoonsu; Lee, Jeongsup; Kim, Kyoung-Kook; Choi, Sang-Jun; Cho, Soohaeng

2014-03-01

418

Dynamic switching characteristics of InGaAsP/InP multimode interference optical waveguide switch.  

PubMed

Multimode interference (MMI) waveguide switches show promise for switch in optical packet switching (OPS). In this work, we fabricated 1 x 4 InGaAsP/InP MMI waveguide switch device which consists of a 1 x 4 MMI splitter, 4 equally spaced single-mode waveguides with phase shifters, and a 4 x 4 MMI combiner. Good crosstalk and extinction ratio of -14.47 dB and 23.39 dB, respectively, are obtained. In addition, we experimentally demonstrate dynamic switching, and the rise and fall time of 1.4 ns and 1.2 ns, respectively, are obtained. PMID:20052045

Tomofuji, Shinji; Matsuo, Shinji; Kakitsuka, Takaaki; Kitayama, Ken-ichi

2009-12-21

419

47 CFR 32.6211 - Non-digital switching expense.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Non-digital switching expense. 32...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Accounts § 32.6211 Non-digital switching expense. This...expenses associated with non-digital electronic switching...

2010-10-01

420

47 CFR 32.2212 - Digital electronic switching.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 false Digital electronic switching. 32...Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED...Sheet Accounts § 32.2212 Digital electronic switching. ...of stored program control digital switches and their...

2010-10-01

421

21 CFR 870.2350 - Electrocardiograph lead switching adaptor.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Electrocardiograph lead switching adaptor. 870.2350 Section...Devices § 870.2350 Electrocardiograph lead switching adaptor. (a) Identification. An electrocardiograph lead switching adaptor is a passive...

2011-04-01

422

21 CFR 870.2350 - Electrocardiograph lead switching adaptor.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Electrocardiograph lead switching adaptor. 870.2350 Section...Devices § 870.2350 Electrocardiograph lead switching adaptor. (a) Identification. An electrocardiograph lead switching adaptor is a passive...

2012-04-01

423

21 CFR 870.2350 - Electrocardiograph lead switching adaptor.  

...2014-04-01 false Electrocardiograph lead switching adaptor. 870.2350 Section...Devices § 870.2350 Electrocardiograph lead switching adaptor. (a) Identification. An electrocardiograph lead switching adaptor is a passive...

2014-04-01

424

21 CFR 870.2350 - Electrocardiograph lead switching adaptor.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Electrocardiograph lead switching adaptor. 870.2350 Section...Devices § 870.2350 Electrocardiograph lead switching adaptor. (a) Identification. An electrocardiograph lead switching adaptor is a passive...

2010-04-01

425

21 CFR 870.2350 - Electrocardiograph lead switching adaptor.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Electrocardiograph lead switching adaptor. 870.2350 Section...Devices § 870.2350 Electrocardiograph lead switching adaptor. (a) Identification. An electrocardiograph lead switching adaptor is a passive...

2013-04-01

426

The Target of Task Switching Darryl W. Schneider  

E-print Network

The Target of Task Switching Darryl W. Schneider Carnegie Mellon University and Vanderbilt University Gordon D. Logan Vanderbilt University Task switching involves processing target stimuli support the idea that categorical target representations are central to task switching. Keywords: task

Logan, Gordon D.

427

Environmental Qualification of an Actuator Torque Switch  

SciTech Connect

Environmental qualification testing was performed on a modified Limitorque torque switch for the torque switch safety functions in the Limitorque type SMB actuators located inside and outside containment in a nuclear power plant. The torque switch specimen was installed in a Limitorque SMB-1 electric actuator mounted on an 8'' Velan gate valve and operated with a customized programmable logic controller to allow normal torque switch behaviour to be observed. The present paper describes the qualification testing performed. The modified torque switch was aged to a 30-year service life at the normal service conditions for both inside and outside containment. Aging included radiation, thermal and cycle aging. A seismic test and then a combined Loss of Coolant Accident (LOCA) and Main Steam Line Break (MSLB) steam accident simulation were followed. After each stage of aging, functional tests were done to confirm normal insulation resistance, normal contact resistance and normal operation. (authors)

Chan, A.M.; Barreca, S.L. [Kinectrics, Inc., 800 Kipling Avenue Toronto, Ontario M8Z 6C4 (Canada); Kostela, T. [Ontario Power Generation, Inc., 700 University Avenue Toronto, Ontario, M5G 1X6 (Canada)

2006-07-01

428

Push-pull switching power amplifier  

NASA Technical Reports Server (NTRS)

A true push-pull switching power amplifier is disclosed utilizing two dc-to-dc converters. Each converter is comprised of two inductances, one inductance in series with a DC source and the other inductor in series with the output load, and an electrical energy transferring device with storage capability, namely storage capacitance, with suitable switching means between the inductances to obtain DC level conversion, where the switching means allows bidirectional current (and power) flow, and the switching means of one dc-to-dc converter is driven by the complement of a square-wave switching signal for the other dc-to-dc converter for true push-pull operation. For reduction of current ripple, the inductances in each of the two converters may be coupled, and with proper design of the coupling, the ripple can be reduced to zero at either the input or the output, but preferably the output.

Cuk, Slobodan M. (Inventor)

1980-01-01

429

Photonic switching devices based on semiconductor nanostructures  

E-print Network

Squeezing and guiding light into semiconductor nanostructures delivers revolutionary concepts of photonic devices, which may offer a practical pathway towards power-efficient optical networks. In this review, we consider photonic switches using semiconductor quantum dots (QDs) and photonic cavities. By intuitively introducing in a field enhancement factor, the optical nonlinearity of nano-photonic switches can be understood and this has shown their unique features to dramatically improve the power-density/speed limitation that has lain in conventional photonic switches for decades. In addition, the power consumption has been reduced due to the atom-like characterization of QDs as well as the nano-size footprint of photonic cavities. Based on this theoretical perspective, the current progress of QD/cavity switches is reviewed in terms of various optical nonlinearities which have been employed to demonstrate photonic switching at the nanoscale. Emerging functionalities enabled by cavity nonlinear effects such a...

Jin, Chao-Yuan

2013-01-01

430

Low Power Switching for Antenna Reconfiguration  

NASA Technical Reports Server (NTRS)

Methods and systems for low power switching are provided. In one embodiment, an optical switching system is provided. The system comprises at least one optically controlled switch adapted to maintain one of an open state and a closed state based on an associated light signal; and at least one light source adapted to output the associated light signal to the at least one switch, wherein the at least one light source cycles the light signal on and off, wherein the at least one light source is cycled on for a sufficient duration of time and with a sufficient periodicity to maintain the optically controlled switch in one of an open state and a closed state.

Bauhahn, Paul E. (Inventor); Becker, Robert C. (Inventor); Meyers, David W. (Inventor); Muldoon, Kelly P. (Inventor)

2008-01-01

431

Seismic switch for strong motion measurement  

DOEpatents

A seismic switching device is described that has an input signal from an existing microseismic station seismometer and a signal from a strong motion measuring instrument. The seismic switch monitors the signal level of the strong motion instrument and passes the seismometer signal to the station data telemetry and recording systems. When the strong motion instrument signal level exceeds a user set threshold level, the seismometer signal is switched out and the strong motion signal is passed to the telemetry system. The amount of time the strong motion signal is passed before switching back to the seismometer signal is user controlled between 1 and 15 seconds. If the threshold level is exceeded during a switch time period, the length of time is extended from that instant by one user set time period. 11 figs.

Harben, P.E.; Rodgers, P.W.; Ewert, D.W.

1995-05-30

432

Seismic switch for strong motion measurement  

DOEpatents

A seismic switching device that has an input signal from an existing microseismic station seismometer and a signal from a strong motion measuring instrument. The seismic switch monitors the signal level of the strong motion instrument and passes the seismometer signal to the station data telemetry and recording systems. When the strong motion instrument signal level exceeds a user set threshold level, the seismometer signal is switched out and the strong motion signal is passed to the telemetry system. The amount of time the strong motion signal is passed before switching back to the seismometer signal is user controlled between 1 and 15 seconds. If the threshold level is exceeded during a switch time period, the length of time is extended from that instant by one user set time period.

Harben, Philip E. (Oakley, CA); Rodgers, Peter W. (Santa Barbara, CA); Ewert, Daniel W. (Patterson, CA)

1995-01-01

433

Microwave switching power divider. [antenna feeds  

NASA Technical Reports Server (NTRS)

A pair of parallel, spaced-apart circular ground planes define a microwave cavity with multi-port microwave power distributing switching circuitry formed on opposite sides of a thin circular dielectric substrate disposed between the ground planes. The power distributing circuitry includes a conductive disk located at the center of the substrate and connected to a source of microwave energy. A high speed, low insertion loss switching diode and a dc blocking capacitor are connected in series between the outer end of a transmission line and an output port. A high impedance, microwave blocking dc bias choke is connected between each switching diode and a source of switching current. The switching source forward biases the diodes to couple microwave energy from the conductive disk to selected output ports and, to associated antenna elements connected to the output ports to form a synthesized antenna pattern.

Stockton, R. J.; Johnson, R. W. (inventors)

1981-01-01

434

Nanoscale resistive switching devices: mechanisms and modeling.  

PubMed

Resistive switching devices (also termed memristive devices or memristors) are two-terminal nonlinear dynamic electronic devices that can have broad applications in the fields of nonvolatile memory, reconfigurable logic, analog circuits, and neuromorphic computing. Current rapid advances in memristive devices in turn demand better understanding of the switching mechanism and the development of physics-based as well as simplified device models to guide future device designs and circuit-level applications. In this article, we review the physical processes behind resistive switching (memristive) phenomena and discuss the experimental and modeling efforts to explain these effects. In this article three categories of devices, in which the resistive switching effects are driven by cation migration, anion migration, and electronic effects, will be discussed. The fundamental driving forces and the stochastic nature of resistive switching will also be discussed. PMID:24057010

Yang, Yuchao; Lu, Wei

2013-11-01

435

Thiol-based redox switches.  

PubMed

Regulation of protein function through thiol-based redox switches plays an important role in the response and adaptation to local and global changes in the cellular levels of reactive oxygen species (ROS). Redox regulation is used by first responder proteins, such as ROS-specific transcriptional regulators, chaperones or metabolic enzymes to protect cells against mounting levels of oxidants, repair the damage and restore redox homeostasis. Redox regulation of phosphatases and kinases is used to control the activity of select eukaryotic signaling pathways, making reactive oxygen species important second messengers that regulate growth, development and differentiation. In this review we will compare different types of reversible protein thiol modifications, elaborate on their structural and functional consequences and discuss their role in oxidative stress response and ROS adaptation. This article is part of a Special Issue entitled: Thiol-Based Redox Processes. PMID:24657586

Groitl, Bastian; Jakob, Ursula

2014-08-01

436

Input-to-state stability of switched nonlinear systems with time delays under asynchronous switching.  

PubMed

This paper is concerned with analyzing input-to-state stability (ISS) for a class of switched nonlinear systems with time delays under asynchronous switching. Due to the existence of switching delay, the switching of the controller does not coincide accurately with the switching of the system.When the subsystem is stabilized with the matched controller, the subsystem is ISS; otherwise, the subsystem may be not ISS. We establish efficient condition, in terms of an upper bound on the switching delay, and in terms of a lower bound on the matched time intervals for the subsystem and the controller, which ensures ISS for the whole switched nonlinear system. Finally, an illustrative example is presented to demonstrate the efficacy of the results. PMID:23757523

Wang, Yue-E; Sun, Xi-Ming; Shi, Peng; Zhao, Jun

2013-12-01

437

Unity power factor switching regulator  

NASA Technical Reports Server (NTRS)

A single or multiphase boost chopper regulator operating with unity power factor, for use such as to charge a battery is comprised of a power section for converting single or multiphase line energy into recharge energy including a rectifier (10), one inductor (L.sub.1) and one chopper (Q.sub.1) for each chopper phase for presenting a load (battery) with a current output, and duty cycle control means (16) for each chopper to control the average inductor current over each period of the chopper, and a sensing and control section including means (20) for sensing at least one load parameter, means (22) for producing a current command signal as a function of said parameter, means (26) for producing a feedback signal as a function of said current command signal and the average rectifier voltage output over each period of the chopper, means (28) for sensing current through said inductor, means (18) for comparing said feedback signal with said sensed current to produce, in response to a difference, a control signal applied to the duty cycle control means, whereby the average inductor current is proportionate to the average rectifier voltage output over each period of the chopper, and instantaneous line current is thereby maintained proportionate to the instantaneous line voltage, thus achieving a unity power factor. The boost chopper is comprised of a plurality of converters connected in parallel and operated in staggered phase. For optimal harmonic suppression, the duty cycles of the switching converters are evenly spaced, and by negative coupling between pairs 180.degree. out-of-phase, peak currents through the switches can be reduced while reducing the inductor size and mass.

Rippel, Wally E. (Inventor)

1983-01-01

438

49 CFR 229.87 - Hand-operated switches.  

Code of Federal Regulations, 2012 CFR

...Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD LOCOMOTIVE SAFETY STANDARDS Safety Requirements Electrical System § 229.87 Hand-operated switches. All hand-operated switches carrying...

2012-10-01

439

49 CFR 229.87 - Hand-operated switches.  

Code of Federal Regulations, 2011 CFR

...Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD LOCOMOTIVE SAFETY STANDARDS Safety Requirements Electrical System § 229.87 Hand-operated switches. All hand-operated switches carrying...

2011-10-01

440

49 CFR 229.87 - Hand-operated switches.  

Code of Federal Regulations, 2013 CFR

...Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD LOCOMOTIVE SAFETY STANDARDS Safety Requirements Electrical System § 229.87 Hand-operated switches. All hand-operated switches carrying...

2013-10-01

441

49 CFR 229.87 - Hand-operated switches.  

Code of Federal Regulations, 2010 CFR

...Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD LOCOMOTIVE SAFETY STANDARDS Safety Requirements Electrical System § 229.87 Hand-operated switches. All hand-operated switches carrying...

2010-10-01

442

Call for Papers: Photonics in Switching  

NASA Astrophysics Data System (ADS)

Call for Papers: Photonics in Switching

Guest Editors:

Lena Wosinska, Royal Institute of Technology (KTH) / ICT Sweden Madeleine Glick, Intel Research, Cambridge, UK

Technologies based on DWDM systems allow data transmission with bit rates of Tbit/s on a single fiber. To facilitate this enormous transmission volume, high-capacity and high-speed network nodes become inevitable in the optical network. Wideband switching, WDM switching, optical burst switching (OBS), and optical packet switching (OPS) are promising technologies for harnessing the bandwidth of WDM optical fiber networks in a highly flexible and efficient manner. As a number of key optical component technologies approach maturity, photonics in switching is becoming an increasingly attractive and practical solution for the next-generation of optical networks. The scope of this special issue is focused on the technology and architecture of optical switching nodes, including the architectural and algorithmic aspects of high-speed optical networks.

Scope of Submission

The scope of the papers includes, but is not limited to, the following topics:
  • WDM node architectures
  • Novel device technologies enabling photonics in switching, such as optical switch fabrics, optical memory, and wavelength conversion
  • Routing protocols
  • WDM switching and routing
  • Quality of service
  • Performance measurement and evaluation
  • Next-generation optical networks: architecture, signaling, and control
  • Traffic measurement and field trials
  • Optical burst and packet switching
  • OBS/OPS node architectures
  • Burst/Packet scheduling and routing algorithms
  • Contention resolution/avoidance strategies
  • Services and applications for OBS/OPS (e.g., grid networks, storage-area networks, etc.)
  • Burst assembly and ingress traffic shaping
  • Hybrid OBS/TDM or OBS/wavelength routing

Manuscript Submission

To submit to this special issue, follow the normal procedure for submission to JON and select ``Photonics in Switching' in the features indicator of the online submission form. For all other questions relating to this feature issue, please send an e-mail to jon@osa.org, subject line ``Photonics in Switching.' Additional information can be found on the JON website: http://www.osa-jon.org/journal/jon/author.cfm. Submission Deadline: 15 September 2006

Wosinska, Lena; Glick, Madeleine

2006-04-01

443

Organization of the channel-switching process in parallel computer systems based on a matrix optical switch  

NASA Technical Reports Server (NTRS)

After a classification and analysis of electronic and optoelectronic switching devices, the design principles and structure of a matrix optical switch is described. The switching and pair-exclusion operations in this type of switch are examined, and a method for the optical switching of communication channels is elaborated. Finally, attention is given to the structural organization of a parallel computer system with a matrix optical switch.

Golomidov, Y. V.; Li, S. K.; Popov, S. A.; Smolov, V. B.

1986-01-01

444

Staged circuit switching for network computers  

SciTech Connect

Staged cricuit switching (SCS) is a message-switching technique which combines a new protocol with new communication hardware. Protocol and hardware are designed specifically for networks which are intended to function as integrated, general-purpose MIMD machines, i.e. for network computers. The SCS protocol is a form of circuit switching which degrades automatically into packet switching when unavailable output lines make further extension of a partial circuit impossible. The SCS hardware uses a front-end crossbar switch to multiplex some small number of communication channels among all of a given node's incident links. Together, hardware and protocol represent an attempt to convert spare bandwidth into lower network delays. They also allow experimentation with networks which reconfigure themselves dynamically in response to measured traffic patterns. SCS is compared with packet switching, circuit switching and the virtual cut-through protocol of P. Kermani and L.Kleinrock (see Comput. Networks, vol.3, p.267, 1979, and IEEE Trans. Comput. C-29,12, p.1052, December 1980), and an SCS implementation designed for the SBN network computer is discussed. 23 references.

Arango, M.; Gelernter, D.; Badr, H.; Bernstein, A.J.

1983-03-01

445

A 'sticky' interhemispheric switch in bipolar disorder?  

PubMed Central

Despite years of research into bipolar disorder (manic depression), its underlying pathophysiology remains elusive. It is widely acknowledged that the disorder is strongly heritable, but the genetics are complex with less than full concordance in monozygotic twins and at least four susceptibility loci identified. We propose that bipolar disorder is the result of a genetic propensity for slow interhemispheric switching mechanisms that become 'stuck' in one or the other state. Because slow switches are also 'sticky' when compared with fast switches, the clinical manifestations of bipolar disorder may be explained by hemispheric activation being 'stuck' on the left (mania) or on the right (depression). Support for this 'sticky' interhemispheric switching hypothesis stems from our recent observation that the rate of perceptual alternation in binocular rivalry is slow in euthymic subjects with bipolar disorder (n = 18, median = 0.27 Hz) compared with normal controls (n = 49, median = 0.60 Hz, p < 0.0005). We have presented evidence elsewhere that binocular rivalry is itself an interhemispheric switching phenomenon. The rivalry alternation rate (putative interhemispheric switch rate) is robust in a given individual, with a test-retest correlation of more than 0.8, making it suitable for genetic studies. The interhemispheric switch rate may provide a trait-dependent biological marker for bipolar disorder. PMID:9872002

Pettigrew, J D; Miller, S M

1998-01-01

446

All-optical broadcasting switch fabric architecture for gigabit switching router (GSR)  

NASA Astrophysics Data System (ADS)

In current high performance IP Gigabit Switching Router (GSR) design, one of the key issues is about switching fabrics. In the traditional bus-based router architectures, the data transfer rate of copper backplanes will soon reach the speed limit because of connector reflections and crosstalk. An optical switching fabric technology is necessary in order to satisfy the demand for high bandwidth and line switching rate. In this paper we firstly present a novel all-optical broadcasting switch fabric design scheme based on broadcasting bus architecture. In this section we also discuss the advantages and disadvantages of this kind of architecture and demonstrate that this kind of switching fabric architecture have no interior blocking as well as none I/O blocking (e.g. HOL). Secondly, we discuss such implementation scheme of all-optical broadcasting switch fabric architecture as queuing, scheduling and multicasting. Finally we get a conclusion that all-optical broadcasting switch fabric is one of the cost-effective solutions to design high-speed, scalable and simple switch fabric compared with complicated electric crossbar switch fabrics in GSR design.

Wei, Wei; Zeng, QingJi

2001-10-01

447

Switching and enhanced bistability in an asymmetric nonlinear directional coupler with a metamaterial channel  

NASA Astrophysics Data System (ADS)

We numerically simulate the propagation and switching of ultra-short pulses in a metamaterial nonlinear directional asymmetric coupler where one of the guides is a conventional medium with a positive refraction index having a decreasing Kerr nonlinearity. The second guide is based in a metamaterial. A complete study of the nonlinear dynamics of ultra-short pulses propagation and switching in this new nonlinear directional coupler, including the transmission characteristics, bistability, critical power, compression factor and extinction coefficients are presented and compared to those of a conventional coupler. We conclude that the conventional coupler has higher transmission efficiency and extinction rate when compared with the metamaterial coupler. However the metamaterial coupler presents bistability which opens the possibility of such device to be used in a large variety of optical switching, storage and logical gates. We show that the input power range leading to bistability can be optimized by controlling the profile of the nonlinear refraction index of the conventional channel.

Coelho, A. G.; Queiroz, A. S. B.; da Silva, M. G.; Lyra, M. L.; Sombra, A. S. B.

2013-05-01

448

Universal Ferroelectric Switching Dynamics of Vinylidene Fluoride-trifluoroethylene Copolymer Films  

NASA Astrophysics Data System (ADS)

In this work, switching dynamics of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer films are investigated over unprecedentedly wide ranges of temperature and electric field. Remarkably, domain switching of copolymer films obeys well the classical domain nucleation and growth model although the origin of ferroelectricity in organic ferroelectric materials inherently differs from the inorganic counterparts. A lower coercivity limit of 50 MV/m and 180° domain wall energy of 60 mJ/m2 are determined for P(VDF-TrFE) films. Furthermore, we discover in copolymer films an anomalous temperature-dependent crossover behavior between two power-law scaling regimes of frequency-dependent coercivity, which is attributed to the transition between flow and creep motions of domain walls. Our observations shed new light on the switching dynamics of semi-crystalline ferroelectric polymers, and such understandings are critical for realizing their reliable applications.

Hu, Wei Jin; Juo, Deng-Ming; You, Lu; Wang, Junling; Chen, Yi-Chun; Chu, Ying-Hao; Wu, Tom

2014-04-01

449

Universal ferroelectric switching dynamics of vinylidene fluoride-trifluoroethylene copolymer films.  

PubMed

In this work, switching dynamics of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer films are investigated over unprecedentedly wide ranges of temperature and electric field. Remarkably, domain switching of copolymer films obeys well the classical domain nucleation and growth model although the origin of ferroelectricity in organic ferroelectric materials inherently differs from the inorganic counterparts. A lower coercivity limit of 50?MV/m and 180° domain wall energy of 60?mJ/m(2) are determined for P(VDF-TrFE) films. Furthermore, we discover in copolymer films an anomalous temperature-dependent crossover behavior between two power-law scaling regimes of frequency-dependent coercivity, which is attributed to the transition between flow and creep motions of domain walls. Our observations shed new light on the switching dynamics of semi-crystalline ferroelectric polymers, and such understandings are critical for realizing their reliable applications. PMID:24759786

Hu, Wei Jin; Juo, Deng-Ming; You, Lu; Wang, Junling; Chen, Yi-Chun; Chu, Ying-Hao; Wu, Tom

2014-01-01

450

New Insights into VEGF-A Alternative Splicing: Key Regulatory Switching in the Pathological Process  

PubMed Central

Vascular endothelial growth factor (VEGF-A) is one of the most important regulatory factors in pathological and physiological angiogenesis. Alternative splicing is a complicated molecular process in VEGF-A gene expression which adds complexity to VEGF-A biology. Among all VEGF-A exons, alternative splicing of exon 8 is the key determinant of isoform switching from pro-angio-genic VEGF-xxx to anti-angiogenic VEGF-xxxb. This is known as a key molecular switching in many pathological situations. In fact, the balance between VEGF-xxx and VEGF-xxxb isoforms is a critical controlling switch in both conditions of health and disease. Here, the properties of VEGF-xxx and VEGF-xxxb isoforms were discussed and their regulatory mechanism and their roles in certain pathological processes were evaluated. In summary, it was suggested that C-terminal VEGF-A alternative splicing can provide a new treatment opportunity in angiogenic diseases.

Dehghanian, Fariba; Hojati, Zohreh; Kay, Maryam

2014-01-01

451

Module 5: Switches, Fuses, and Circuit Breakers  

NSDL National Science Digital Library

This module on switches, fuses, and circuit breakers contains two experiments and a link to allaboutcircuits.com. The module was created by the California Regional Consortium for Engineering Advances in Technological Education (CREATE) which is “a joint effort between seven community colleges and over 30 large high tech engineering/technology employers.” This collection of study modules encourages students to learn about the basics of DC electronics and circuits. Module 5 teaches students about the Physics of Conductors and Insulators as well as Electromechanical Devices and Switches and Switching Circuits.

2014-08-15

452

How Do You Make Loops and Switches?  

NSDL National Science Digital Library

Students learn how to program using loops and switches. They see how loops enable us to easily and efficiently tell a computer to keep repeating an operation. They also see that switches permit programs to follow different instructions based on whether or not preconditions are fulfilled. Using the LEGO® MINDSTORMS® NXT robots, sensors and software, student pairs perform three mini programming activities using loops and switches individually, and then combined. With practice, they incorporate these tools into their programming skill sets in preparation for the associated activity. A PowerPoint® presentation, pre/post quizzes and worksheet are provided.

GK-12 Program, Computational Neurobiology Center,

453

Optical Switching In "Complementary" Electrochromic Windows  

NASA Astrophysics Data System (ADS)

The electrochemical and optical switching characteristics of a variety of variable transmittance complementary electrochromic windows are presented. The complementary configurations are based on hydrogen insertion in cathodically coloring amorphous WO3 and crystalline KxWO3+(x/2) combined with anodically coloring IrO2. These windows exhibit typical transmittance modulations from 70 to 15% in the visible spectrum and undergo ca. 4000 to 6000 switching cycles without degradation. The optical switching characteristics are discussed in terms of the complementary device structure and the electrochemistry of the individual electrochromic layers.

Cogan, Stuart F.; Plante, Timothy D.; McFadden, Robert S.; Rauh, R. David

1987-02-01

454

Neural network architecture for crossbar switch control  

NASA Technical Reports Server (NTRS)

A Hopfield neural network architecture for the real-time control of a crossbar switch for switching packets at maximum throughput is proposed. The network performance and processing time are derived from a numerical simulation of the transitions of the neural network. A method is proposed to optimize electronic component parameters and synaptic connections, and it is fully illustrated by the computer simulation of a VLSI implementation of 4 x 4 neural net controller. The extension to larger size crossbars is demonstrated through the simulation of an 8 x 8 crossbar switch controller, where the performance of the neural computation is discussed in relation to electronic noise and inhomogeneities of network components.

Troudet, Terry P.; Walters, Stephen M.

1991-01-01

455

CS Network Testbed Switches: Cisco, Asant, Packeteer, ...  

E-print Network

CS Network Testbed Switches: Cisco, Asanté, Packeteer, ... LRx LRx LRx Linux Router Nodes P2 P2 P2 PES-2 Cluster PatchPanel N2 Gulfstream C6C6a C6C6C6C6a 12-port Gigabit Ethernet Switch 3Com Super/5/06 Tornado C2 C2C2 36-port Fast Ethernet Switch 3Com SuperStack II 3900 N1 Typhoon C1 C1 C1 36-port Fast

Lewis, Robert Michael

456

The Cost of a Voluntary Task Switch  

Microsoft Academic Search

ABSTRACT—Task-switching paradigms,are widely used to study executive control. However, standard paradigms may not re- quire active control to switch tasks. We examined,voluntary,task switching by having,subjects choose which,task to perform,on a series of bivalent stimuli. Subjects performed,parity or magni- tude judgments,on single digits. Instructions were to perform,the two tasks equally often and in a random,order. The response-to- stimulus interval (RSI) was

Catherine M. Arrington; Gordon D. Logan

2004-01-01

457

Metal vapor arc switch electromagnetic accelerator technology  

NASA Technical Reports Server (NTRS)

A multielectrode device housed in an insulator vacuum vessel, the metal vapor vacuum switch has high power capability and can hold off voltages up to the 100 kilovolt level. Such switches can be electronically triggered and can interrupt or commutate at a zero current crossing. The physics of arc initiation, arc conduction, and interruption are examined, including material considerations; inefficiencies; arc modes; magnetic field effects; passive and forced extinction; and voltage recovery. Heating, electrode lifetime, device configuration, and external circuit configuration are discussed. The metal vapor vacuum switch is compared with SCRs, GTOs, spark gaps, ignitrons, and mechanical breakers.

Mongeau, P. P.

1984-01-01

458

The Critical Review on Facebook Critical Review  

E-print Network

The Critical Review on Facebook Like 136 Critical Review Brown University's Undergraduate Academic the class as a "necessary (boring) evil" but others recommended taking it with Ms. Stange and learning about

Stange, Katherine E.

459

Gastroprotective effect of desmosdumotin C isolated from Mitrella kentii against ethanol-induced gastric mucosal hemorrhage in rats: possible involvement of glutathione, heat-shock protein-70, sulfhydryl compounds, nitric oxide, and anti-Helicobacter pylori activity  

PubMed Central

Background Mitrella kentii (M. kentii) (Bl.) Miq, is a tree-climbing liana that belongs to the family Annonaceae. The plant is rich with isoquinoline alkaloids, terpenylated dihydrochalcones and benzoic acids and has been reported to possess anti-inflammatory activity. The purpose of this study is to assess the gastroprotective effects of desmosdumotin C (DES), a new isolated bioactive compound from M. kentii, on gastric ulcer models in rats. Methods DES was isolated from the bark of M. kentii. Experimental rats were orally pretreated with 5, 10 and 20 mg/kg of the isolated compound and were subsequently subjected to absolute ethanol-induced acute gastric ulcer. Gross evaluation, mucus content, gastric acidity and histological gastric lesions were assessed in vivo. The effects of DES on the anti-oxidant system, non-protein sulfhydryl (NP-SH) content, nitric oxide (NO)level, cyclooxygenase-2 (COX-2) enzyme activity, bcl-2-associated X (Bax) protein expression and Helicabacter pylori (H pylori) were also investigated. Results DES pre-treatment at the administered doses significantly attenuated ethanol-induced gastric ulcer; this was observed by decreased gastric ulcer area, reduced or absence of edema and leucocytes infiltration compared to the ulcer control group. It was found that DES maintained glutathione (GSH) level, decreased malondialdehyde (MDA) level, increased NP-SH content and NO level and inhibited COX-2 activity. The compound up regulated heat shock protein-70 (HSP-70) and down regulated Bax protein expression in the ulcerated tissue. DES showed interesting anti-H pylori effects. The efficacy of DES was accomplished safely without any signs of toxicity. Conclusions The current study reveals that DES demonstrated gastroprotective effects which could be attributed to its antioxidant effect, activation of HSP-70 protein, intervention with COX-2 inflammatory pathway and potent anti H pylori effect. PMID:23866830

2013-01-01

460

Simulation of mixed switched-capacitor/digital networks with signal-driven switches  

NASA Astrophysics Data System (ADS)

The simulation of mixed switched-capacitor/digital (SC/D) networks containing capacitors, independent and linear-dependent voltage sources, switches controlled either by periodic or nonperiodic Boolean signals, latched comparators, and logic gates is considered. A unified linear switched-capacitor network (SCN) and mixed SC/D network simulator, SWITCAP2, and its applications to several widely used and novel nonlinear SCNs are discussed. The switches may be controlled by periodic waveforms and by nonperiodic waveforms from the outputs of comparators and logic gates. The signal-dependent modification of network topology through the comparators, logic gates, and signal-driven switches makes the modeling of various nonlinear switched-capacitor circuits possible. Simulation results for a pulse-code modulation (PCM) voice encoder, a sigma-delta modulator, a neural network, and a phase-locked loop (PLL) are presented to demonstrate the flexibility of the approach.

Suyama, Ken; Tsividis, Yannis P.; Fang, San-Chin

1990-12-01

461

Comparison of circuit switching and packet switching for data transfer in two simple image processing algorithms  

SciTech Connect

The communication costs for parallel versions of two simple algorithms used in image processing are compared in packet switching and circuit switching formulations. The two algorithms are smoothing and histogramming. The histogramming algorithm, the recursive doubling algorithm of Stone (1975), is studied over a range of processor numbers and pixel intensity resolution. The packet and circuit switching properties of the interconnection networks of the multiprocessor systems are based on two network architectured multiprocessors which are well-documented in the literature, PASM and TRAC. Communication based upon circuit switching generally gives a somewhat lower communication cost with the advantage increasing with pixel intensity resolution. The results of the analysis suggest a high utility value for including both circuit switching and packet switching functionality in the networks of network architectured multiprocessor systems. 8 references.

Yasrebi, M.; Deshpande, S.; Browne, J.C.

1983-01-01

462

Electrically switched cesium ion exchange  

SciTech Connect

Electrically Switched Ion Exchange (ESIX) is a separation technology being developed as an alternative to conventional ion exchange for removing radionuclides from high-level waste. The ESIX technology, which combines ion exchange and electrochemistry, is geared toward producing electroactive films that are highly selective, regenerable, and long lasting. During the process, ion uptake and elution are controlled directly by modulating the potential of an ion exchange film that has been electrochemically deposited onto a high surface area electrode. This method adds little sodium to the waste stream and minimizes the secondary wastes associated with traditional ion exchange techniques. Development of the ESIX process is well underway for cesium removal using ferrocyanides as the electroactive films. Films having selectivity for perrhenate (a pertechnetate surrogate) over nitrate also have been deposited and tested. A case study for the KE Basin on the Hanford Site was conducted based on the results of the development testing. Engineering design baseline parameters for film deposition, film regeneration, cesium loading, and cesium elution were used for developing a conceptual system. Order of magnitude cost estimates were developed to compare with conventional ion exchange. This case study demonstrated that KE Basin wastewater could be processed continuously with minimal secondary waste and reduced associated disposal costs, as well as lower capital and labor expenditures.

Lilga, M.A.; Orth, R.J.; Sukamto, J.P.H. [Pacific Northwest National Lab., Richland, WA (United States); Schwartz, D.T.; Haight, S.M. [Univ. of Washington, Seattle, WA (United States); Genders, J.D. [Electrosynthesis Co., Inc. (United States)

1997-04-01

463

Electrically Switched Cesium Ion Exchange  

SciTech Connect

This report discusses the results of work to develop Electrically Switched Ion Exchange (ESIX) for separations of ions from waste streams relevant to DOE site clean-up. ESIX combines ion exchange and electrochemistry to provide a selective, reversible method for radionuclide separation that lowers costs and minimizes secondary waste generation typically associated with conventional ion exchange. In the ESIX process, an electroactive ion exchange film is deposited onto. a high surface area electrode, and ion uptake and elution are controlled directly by modulating the potential of the film. As a result, the production of secondary waste is minimized, since the large volumes of solution associated with elution, wash, and regeneration cycles typical of standard ion exchange are not needed for the ESIX process. The document is presented in two parts: Part I, the Summary Report, discusses the objectives of the project, describes the ESIX concept and the approach taken, and summarizes the major results; Part II, the Technology Description, provides a technical description of the experimental procedures and in-depth discussions on modeling, case studies, and cost comparisons between ESIX and currently used technologies.

JPH Sukamto; ML Lilga; RK Orth

1998-10-23

464

A noncovalent switch for lysozyme.  

PubMed

A new concept for the external control of protein activity is presented and demonstrated on the example of an artificial Lysozyme switch. Radical copolymerization of selected methacrylamide-based comonomer units tailored for amino acid residues surrounding the active site furnishes polymeric protein hosts that are able to inhibit enzymatic activity in a highly efficient dose-dependent manner (IC50 approximately 1.0 equiv approximately 0.7 microM). All binding site types on the polymer work cooperatively, using electrostatic attraction, hydrophobic forces, and substrate mimicry. In a native gel electrophoresis, the well-defined 2:1 complex (polymer/protein) migrates to the anode. Even at 250 mM NaCl, a 10-fold polymer excess is able to shut down bacterial cell wall degradation completely. A kinetic investigation points to a competitive mechanism (Lineweaver-Burk plots). CD spectra of pure Lysozyme and its polymer complex are indistinguishable; together with a total lack of preincubation time for maximum inhibition, experimental evidence is thus produced for a preserved tertiary enzyme structure-no denaturation occurs. Addition of the superior complexing agent polyarginine to the enzyme-polymer complex mildly detaches the inhibitor from the protein surface and leads to 90% recovery of enzymatic activity. Thus, Lysozyme could be turned off, on, and off again by consecutive addition of the polymeric inhibitor, polyarginine, and polymer again. PMID:18052064

Wenck, Kirstin; Koch, Sebastian; Renner, Christian; Sun, Wei; Schrader, Thomas

2007-12-26

465

Plasma opening switch conduction scaling  

SciTech Connect

Plasma opening switch (POS) experiments performed on the Hawk generator [Commisso {ital et} {ital al}., Phys. Fluids B {bold 4}, 2368 (1992)] (750 kA, 1.2 {mu}s) determine the dependence of the conduction current and conduction time on plasma density, electrode dimensions, and current rise rate. The experiments indicate that for a range of parameters, conduction is controlled by magnetohydrodynamic (MHD) distortion of the plasma, resulting in a low density region where opening can occur, possibly by erosion. The MHD distortion corresponds to an axial translation of the plasma center-of-mass by half the initial plasma length, leading to a simple scaling relation between the conduction current and time, and the injected plasma density and POS electrode dimensions that is applicable to a large number of POS experiments. For smaller currents and conduction times, the Hawk data suggest a non-MHD conduction limit that may correspond to electromagnetohydrodynamic (EMH) field penetration through the POS plasma. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Weber, B.V.; Commisso, R.J.; Goodrich, P.J.; Grossmann, J.M.; Hinshelwood, D.D.; Ottinger, P.F.; Swanekamp, S.B. [Pulsed Power Physics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375-5000 (United States)] [Pulsed Power Physics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375-5000 (United States)

1995-10-01

466

Double Two Switch Forward Soft Switching PWM DC-DC Converter  

NASA Astrophysics Data System (ADS)

A novel prototype of a double two-switch forward transformer linked zero-voltage and zero-current mode soft-switching (ZVZCS) pulse width modulation (PWM) DC-DC power converter using IGBTs for high power applications is presented. Based on a conventional two-switch forward transformer linked PWM DC-DC converter topology, this converter circuit configuration doesn't include any complex auxiliary resonant circuit. Combining two identical two-switch forward type DC-DC power conversion circuits with a tapped-inductor type DC smoothing filter into a power DC-DC conversion system makes it possible to achieve soft-switching conditions for the active power switches with aid of lossless snubber capacitors and transformer parasitic inductors. Lowered peak voltage across the power switching devices and their related peak current stresses, no transformer saturation effect, reducing of idle and circulating currents through circuit components are practically attained for this converter. This soft-switching PWM DC-DC power converter has some unique advantages such as better power conversion efficiency, lowered output DC ripple current, high power density, constant frequency PWM control scheme, cost effective and wide soft-switching operation range under load variations and PWM regulation settings for high power utilizations. The basic operating principle of the new soft switching power converter treated here is illustrated with approximate periodic steady-state circuit analysis for each mode equivalent circuit. The practical effectiveness of the proposed soft-switching DC-DC power converter is confirmed by the simulation results and is experimentally evaluated on basis of 500W-100kHz breadboard setup using the fast switching IGBTs.

Hamada, Satoshi; Moisseev, Serguei; Koudriavtsev, Oleg; Nakaoka, Mutsuo

467

Granular acoustic switches and logic elements  

NASA Astrophysics Data System (ADS)

Electrical flow control devices are fundamental components in electrical appliances and computers; similarly, optical switches are essential in a number of communication, computation and quantum information-processing applications. An acoustic counterpart would use an acoustic (mechanical) signal to control the mechanical energy flow through a solid material. Although earlier research has demonstrated acoustic diodes or circulators, no acoustic switches with wide operational frequency ranges and controllability have been realized. Here we propose and demonstrate an acoustic switch based on a driven chain of spherical particles with a nonlinear contact force. We experimentally and numerically verify that this switching mechanism stems from a combination of nonlinearity and bandgap effects. We also realize the OR and AND acoustic logic elements by exploiting the nonlinear dynamical effects of the granular chain. We anticipate these results to enable the creation of novel acoustic devices for the control of mechanical energy flow in high-performance ultrasonic devices.

Li, Feng; Anzel, Paul; Yang, Jinkyu; Kevrekidis, Panayotis G.; Daraio, Chiara

2014-10-01

468

Granular acoustic switches and logic elements.  

PubMed

Electrical flow control devices are fundamental components in electrical appliances and computers; similarly, optical switches are essential in a number of communication, computation and quantum information-processing applications. An acoustic counterpart would use an acoustic (mechanical) signal to control the mechanical energy flow through a solid material. Although earlier research has demonstrated acoustic diodes or circulators, no acoustic switches with wide operational frequency ranges and controllability have been realized. Here we propose and demonstrate an acoustic switch based on a driven chain of spherical particles with a nonlinear contact force. We experimentally and numerically verify that this switching mechanism stems from a combination of nonlinearity and bandgap effects. We also realize the OR and AND acoustic logic elements by exploiting the nonlinear dynamical effects of the granular chain. We anticipate these results to enable the creation of novel acoustic devices for the control of mechanical energy flow in high-performance ultrasonic devices. PMID:25354587

Li, Feng; Anzel, Paul; Yang, Jinkyu; Kevrekidis, Panayotis G; Daraio, Chiara

2014-01-01

469

72. LOCK ELECTRICAL SYSTEM CONTROL SWITCH CABINET ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

72. LOCK - ELECTRICAL SYSTEM - CONTROL SWITCH CABINET - PANEL ARRANGEMENT AND DETAILS (ML-5-29/33-FS), March 1934 - Upper Mississippi River 9-Foot Channel Project, Lock & Dam No. 5, Minneiska, Winona County, MN

470

Minimizing spikes in switching-regulator circuits  

NASA Technical Reports Server (NTRS)

Circuit, employing tapped inductor to back-bias rectifying diodes and extra diode to cummutate current, minimizes current spikes that cause premature transistor failure in switching-regulator circuits.

Mclyman, W. T.

1980-01-01

471

Vibration measurements in the switched reluctance motor  

Microsoft Academic Search

Techniques for the measurement of vibrations in switched reluctance motors (SRMs) are given in this paper, together with experimental results. The measured results are compared to each other as well as with finite element calculated results, with good correlation

W. Cai; P. Pillay; Z. Tang; A. Omekanda

2001-01-01

472

Fuel Switching Strategies for the 1990s  

E-print Network

butane in summer resulting from lowered gasoline volatility and various increasing supply factors will create fuel purchasing opportunities. It was found that in-place propane switching capability among manufacturers could be adapted to absorb all...

Cascone, R.

473

46 CFR 112.43-1 - Switches.  

Code of Federal Regulations, 2013 CFR

...112.43-1 Section 112.43-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING EMERGENCY LIGHTING AND POWER SYSTEMS Emergency Lighting Systems § 112.43-1 Switches. An...

2013-10-01

474

46 CFR 112.43-1 - Switches.  

Code of Federal Regulations, 2011 CFR

...112.43-1 Section 112.43-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING EMERGENCY LIGHTING AND POWER SYSTEMS Emergency Lighting Systems § 112.43-1 Switches. An...

2011-10-01

475

Clause chaining, switch reference and coordination  

E-print Network

In this thesis I ponder over a constellation of phenomena that revolve around switch reference and coordination, drawing mainly on their instantiation in Kisedje (Je, Brazil). I start by investigating Klsedje's case system. ...

Nonato, Rafael

2014-01-01

476

Switching Dynamics and the Stress Process  

PubMed Central

This paper shows how maintaining social relationships can be a daily hassle that has implications for the stress process, depending on how often individuals transition, or “switch,” between their various social roles and social settings throughout the day. I use nationally representative time diary data on 7,662 respondents from the 2010 American Time Use Survey to measure individual rates of this switching behavior and to examine how this relates to perceived stress. Regression analysis shows that, net of how many social roles they play and settings they visit on a given day, individuals who switch more frequently between these elements report higher levels of stress. This finding holds for women but not men, suggesting that switching dynamics are disproportionately stressful for women. I close by discussing the implications of the findings for research on gender and health. PMID:25110381

Cornwell, Benjamin

2014-01-01

477

Contralateral disconnection of the rat prelimbic cortex and dorsomedial striatum impairs cue-guided behavioral switching.  

PubMed

Switches in reward outcomes or reward-predictive cues are two fundamental ways in which information is used to flexibly shift response patterns. The rat prelimbic cortex and dorsomedial striatum support behavioral flexibility based on a change in outcomes. The present experiments investigated whether these two brain regions are necessary for conditional discrimination performance in which a switch in reward-predictive cues occurs every three to six trials. The GABA agonists baclofen and muscimol infused into the prelimbic cortex significantly impaired performance leading rats to adopt an inappropriate turn strategy. The NMDA receptor antagonist D-AP5 infused into the dorsomedial striatum or prelimbic cortex and dorsomedial striatum contralateral disconnection impaired performance due to a rat failing to switch a response choice for an entire trial block in about two out of 13 test blocks. In an additional study, contralateral disconnection did not affect nonswitch discrimination performance. The results suggest that the prelimbic cortex and dorsomedial striatum are necessary to support cue-guided behavioral switching. The prelimbic cortex may be critical for generating alternative response patterns while the dorsomedial striatum supports the selection of an appropriate response when cue information must be used to flexibly switch response patterns. PMID:25028395

Baker, Phillip M; Ragozzino, Michael E

2014-08-01

478

Bipolar resistive switching characteristics in CuO/ZnO bilayer structure  

NASA Astrophysics Data System (ADS)

Resistive switching characteristics in Cu/ZnO/AZO (Al-doped ZnO) were investigated. Reproducible bipolar resistance switching properties were observed in the single oxide layer (SL)-based device. To improve the switching performance, a CuO-ZnO bilayer (BL) was used to form a Cu/CuO/ZnO/AZO structure. RS characteristics such as retention time, endurance, variations of threshold voltage as well as distribution of resistance were investigated. The results demonstrated that the BL devices exhibit more excellent switching performance than SL devices. The conduction mechanisms of high and low resistance states can be explained by trap-controlled space charge limited current (SCLC) and Ohmic's Law, respectively. The CuO layer is proposed as a "reservoir" of oxygen ions in set process and acting as an oxygen ions "supplier" in reset process, which plays a critical role in recovery/rupture of filament paths and greatly improves the switching characteristics of the device.

Yang, F.; Wei, M.; Deng, H.

2013-10-01

479

Microwave Power Combiner With Switching Diodes  

NASA Technical Reports Server (NTRS)

In multiple-port microwave power combiner, each of outputs of two or more power amplifiers of same frequency and phase passed to common output port separately or together. Each amplifier connected to combiner through switch consisting of resonant structures, radio-frequency chokes, and diode. Switches not only permit flexiblity in selection of amplifiers but isolate unused amplifiers from network, all while operating at relatively low power loss.

Conroy, B. L.; Postal, R. B.; Boreham, J. F.

1986-01-01

480

WDMJTDM Optical Packet Switched Network for Supercomputing  

Microsoft Academic Search

ABSTRACT A new optical packet switching network and its enabling technologies are investigated for implementation,in a Petaflops scale supercomputer,system. We capitalize on the immense,bandwidth of the optical fiber interconnects by deploying WDM\\/TDM packet payloads. To accommodate current optical switching technologies, the routing operations in the network are drastically simplified and the need for buffering is completely eliminated. This paper presents

Q. Yang; M. F. Arend; G. D. Hughes; F. G. Johnson; K. Bergman

2000-01-01