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Sample records for ac switch peripheries

  1. Non-oxidized porous silicon-based power AC switch peripheries

    PubMed Central

    2012-01-01

    We present in this paper a novel application of porous silicon (PS) for low-power alternating current (AC) switches such as triode alternating current devices (TRIACs) frequently used to control small appliances (fridge, vacuum cleaner, washing machine, coffee makers, etc.). More precisely, it seems possible to benefit from the PS electrical insulation properties to ensure the OFF state of the device. Based on the technological aspects of the most commonly used AC switch peripheries physically responsible of the TRIAC blocking performances (leakage current and breakdown voltage), we suggest to isolate upper and lower junctions through the addition of a PS layer anodically etched from existing AC switch diffusion profiles. Then, we comment the voltage capability of practical samples emanating from the proposed architecture. Thanks to the characterization results of simple Al-PS-Si(P) structures, the experimental observations are interpreted, thus opening new outlooks in the field of AC switch peripheries. PMID:23057856

  2. AC magnetohydrodynamic microfluidic switch

    SciTech Connect

    Lemoff, A V; Lee, A P

    2000-03-02

    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.

  3. Semiconductor ac static power switch

    NASA Technical Reports Server (NTRS)

    Vrancik, J.

    1968-01-01

    Semiconductor ac static power switch has long life and high reliability, contains no moving parts, and operates satisfactorily in severe environments, including high vibration and shock conditions. Due to their resistance to shock and vibration, static switches are used where accidental switching caused by mechanical vibration or shock cannot be tolerated.

  4. Optimization of spin-torque switching using AC and DC pulses

    SciTech Connect

    Dunn, Tom; Kamenev, Alex

    2014-06-21

    We explore spin-torque induced magnetic reversal in magnetic tunnel junctions using combined AC and DC spin-current pulses. We calculate the optimal pulse times and current strengths for both AC and DC pulses as well as the optimal AC signal frequency, needed to minimize the Joule heat lost during the switching process. The results of this optimization are compared against numeric simulations. Finally, we show how this optimization leads to different dynamic regimes, where switching is optimized by either a purely AC or DC spin-current, or a combination AC/DC spin-current, depending on the anisotropy energies and the spin-current polarization.

  5. Experimental investigation of resonant MEMS switch with ac actuation

    NASA Astrophysics Data System (ADS)

    Pal, Jitendra; Zhu, Yong; Wang, Boyi; Lu, Junwei; Khan, Fahimullah; Viet Dao, Dzung; Wang, Yifan

    2016-06-01

    In this letter, modeling, analysis, and experimental investigation for a resonant MEMS switch are presented. The resonant switch harnesses its mechanical resonance to lower the required actuation voltage by a substantial factor over the switch with static actuation. With alternating actuation voltage at its mechanical resonance frequency of 6.6 kHz, the average capacitance is tuned by changing the gap between fixed and movable electrodes. Based on the proposed actuation method, the device offers 57.44% lower actuation voltage compared with the switch with static actuation.

  6. Generalised mc × nc -stage switched-capacitor-voltage-multiplier-based boost DC-AC inverter

    NASA Astrophysics Data System (ADS)

    Chang, Yuen-Haw; Wu, Ming-Zong

    2012-01-01

    A closed-loop scheme of a generalised ? -stage (multistage) switched-capacitor-voltage-multiplier inverter (SCVMI) is proposed by combining a two-phase interleaved phase generator and a sinusoidal-pulse-width-modulation (SPWM) control for low-power boost dc-ac conversion and regulation. In this SCVMI, the power unit contains two parts: SCVM booster (front) and H-bridge (rear). The SCVM booster is composed of two ? -stage SC cells and two ? -stage SC cells in series for a boost dc-dc conversion, and these cells are operated with two-phase non-overlapping clocks of phase generator for a high conversion ratio of ? at most (like a voltage multiplier). The H-bridge consists of four switches for a dc-ac conversion, and these switches are controlled by SPWM not only for realising full-wave operation, but also for enhancing output regulation as well as robustness to source/loading variation. Further, some aspects of theoretical analysis and design are included: SCVMI formulation, steady-state/dynamic analysis, conversion ratio, power efficiency, stability, capacitance selection, output filter and control design. Finally, the closed-loop SCVMI is simulated and the hardware implemented and tested. All the results are illustrated to show the efficacy of the proposed scheme.

  7. Development of an AC power source for CSEM method using full-bridge switching configuration

    NASA Astrophysics Data System (ADS)

    Indrasari, Widyaningrum; Srigutomo, Wahyu; Djamal, Mitra; S, Rahmondia N.

    2015-04-01

    The electromagnetic (EM) method has been widely used in geophysical surveys. It is a non-destructive method that utilizes electromagnetic waves in characterizing subsurface profiles. Generally, EM method can be divided into passive EM and active EM. The passive EM uses the natural electromagnetic field sources, while the active EM or Controlled Source EM (CSEM) uses artificial source to generate electromagnetic wave. In this paper, we present the development of AC power source for CSEM transmitter. As the power source we used AC source with sine wave signal. To satisfy a high power and high voltage in the equipment, we used the full-bridge configuration switching. It works on 990 Hz maximum frequency, and can deliver maximum current of 1.9 A at 620 V. The switching is controlled by microcontroller using Pulse Width Modulation (PWM) and the driver of inverter is built using IGBT. The output frequency can be varied from 1 Hz to 990 Hz. For varied frequencies the harmonic distortion is different due to switching speed. As frequency increase the harmonic distortion also increase. We found that the total harmonic distortion can be reduced to 1 % at the output with 330 Hz.

  8. Switch contact device for interrupting high current, high voltage, AC and DC circuits

    DOEpatents

    Via, Lester C.; Witherspoon, F. Douglas; Ryan, John M.

    2005-01-04

    A high voltage switch contact structure capable of interrupting high voltage, high current AC and DC circuits. The contact structure confines the arc created when contacts open to the thin area between two insulating surfaces in intimate contact. This forces the arc into the shape of a thin sheet which loses heat energy far more rapidly than an arc column having a circular cross-section. These high heat losses require a dramatic increase in the voltage required to maintain the arc, thus extinguishing it when the required voltage exceeds the available voltage. The arc extinguishing process with this invention is not dependent on the occurrence of a current zero crossing and, consequently, is capable of rapidly interrupting both AC and DC circuits. The contact structure achieves its high performance without the use of sulfur hexafluoride.

  9. The Single-phase AC Regulator on Base of Bidirectional IGBT Switches

    NASA Astrophysics Data System (ADS)

    Cimanis, Vladimirs; Hramcovs, Vladimirs; Rankis, Ivars

    2010-01-01

    In the work one of the methods for regulation of sinus shape AC voltage for middle-power loads with activeinductive character is observed. Such a regulator keeping output voltage of sinus shape must be fast-reacting and work in closed-loop system. It's shown, that for providing such features Buck and Boost pulse regulators can be applied. The only difference from DC pulse converters is that electronic switches in the system must be with bidirectional conductivity. For this reason an IGBT transistors can be applied with implemented in structure reverse diodes and if such two transistors are connected in series and with contrary conductivity then at activating both one of them will be in on-state. Realization of AC regulators with such switches is described in the work. Results of computer modeling also are given. Output voltage ripples are investigated on subject of their range and efficiency of filtering equipment on LC base. Such regulators can be applied for instance in electrical transport self supply systems.

  10. Use of an AC electric field in galvanotactic on/off switching of the motion of a microstructure blotted by Serratia marcescens

    NASA Astrophysics Data System (ADS)

    Tran, Trung-Hieu; Hyung Kim, Dal; Kim, Jihoon; Jun Kim, Min; Byun, Doyoung

    2011-08-01

    In this study, we manipulated the swimming direction of bacteria and controlled the switching off movement by using dc and ac galvanotaxis. The microstructures blotted by Serratia marcescens could be spontaneously manipulated and switched off at the desired position. The optimum ac frequency for switching off the microstructural motion was 7 Hz. We built a mathematical model to analyze and understand the oscillating motion of microstructure.

  11. A high switching frequency IGBT PWM rectifier/inverter system for ac motor drives operating from single phase supply

    NASA Astrophysics Data System (ADS)

    Thiyagarajah, K.; Ranganathan, V. T.; Ramakrishna Iyengar, B. S.

    1991-10-01

    A pulse-width-modulated (PWM) rectifier/inverter system using insulated-gate-bipolar-transistors (IGBTs), capable of switching at 20 kHz is reported. The base drive circuit for the IGBT, incorporating short-circuit protection, is presented. The inverter uses an Undeland snubber together with a simple energy recovery circuit, which ensures reliable and efficient operation even for 20 kHz switching. The front end for the system is a regenerative single phase full-bridge IGBT inverter along with an ac reactor. Steady-state design considerations are explained, and control techniques for unity power factor operation and fast current control of the front end converter, in a rotating as well as a stationary reference frame, are discussed and compared. Results from computer simulations and experimental results for a 1.5-kW prototype system are presented.

  12. Effective variable switching point predictive current control for ac low-voltage drives

    NASA Astrophysics Data System (ADS)

    Stolze, Peter; Karamanakos, Petros; Kennel, Ralph; Manias, Stefanos; Endisch, Christian

    2015-07-01

    This paper presents an effective model predictive current control scheme for induction machines driven by a three-level neutral point clamped inverter, called variable switching point predictive current control. Despite the fact that direct, enumeration-based model predictive control (MPC) strategies are very popular in the field of power electronics due to their numerous advantages such as design simplicity and straightforward implementation procedure, they carry two major drawbacks. These are the increased computational effort and the high ripples on the controlled variables, resulting in a limited applicability of such methods. The high ripples occur because in direct MPC algorithms the actuating variable can only be changed at the beginning of a sampling interval. A possible remedy for this would be to change the applied control input within the sampling interval, and thus to apply it for a shorter time than one sample. However, since such a solution would lead to an additional overhead which is crucial especially for multilevel inverters, a heuristic preselection of the optimal control action is adopted to keep the computational complexity at bay. Experimental results are provided to verify the potential advantages of the proposed strategy.

  13. Analysis of three-phase rectifiers with AC-side switches and interleaved three-phase voltage-source converters

    NASA Astrophysics Data System (ADS)

    Miller, Stephanie Katherine Teixeira

    Of all the alternative and renewable energy sources, wind power is the fastest growing alternative energy source with a total worldwide capacity of over 93 GW as of the end of 2007. However, making wind energy a sustainable and reliable source of electricity doesn't come without its set of challenges. As the wind turbines increase in size and turbine technology moves towards off-shore wind farms and direct drive transmission, the need for a reliable and efficient power electronics interface to convert the variable-frequency variable-magnitude output of the wind turbine's generator into the fixed-frequency fixed-magnitude voltage of the utility grid is critical. This dissertation investigates a power electronics interface envisioned to operate with an induction generator-based variable-speed wind turbine. The research conclusions and the interface itself are applicable to a variety of applications, including uninterruptible power supplies, industrial drives, and power quality applications, among others. The three-phase PWM rectifiers with ac-side bidirectional switches are proposed as the rectification stage of the power electronics interface. Modulation strategies are proposed for the rectifiers and the operation of the rectifiers in conjunction with an induction generator is demonstrated. The viability of using these rectifiers in place of the standard three-phase voltage-source converter is analyzed by comparing losses and common-mode voltage generation of the two topologies. Parallel three-phase voltage-source converter modules operated in an interleaved fashion are proposed for the inversion stage of the power electronics interface. The interleaved three-phase voltage-source converters are analyzed by deriving analytical models for the common-mode voltage, ac phase current, and dc-link current to reveal their spectra and the harmonic cancellation effects of interleaving. The practical problem of low frequency circulating current in parallel voltage

  14. Power Quality Improvement in Bridgeless Ac-Dc Converter Based Multi-output Switched Mode Power Supply

    NASA Astrophysics Data System (ADS)

    Singh, Shihka; Singh, Bhim; Bhuvaneswari, G.; Bist, Vashist

    2014-12-01

    Computer power supplies are required to have multiple isolated regulated dc voltages with low ripple content and high input power factor at the utility interface. A dc-dc converter is used for obtaining these isolated multi-output dc voltages with excellent regulation. In this paper, a non-isolated ac-dc converter is proposed as the first stage converter to obtain a regulated dc output rather than using a simple uncontrolled diode bridge rectifier at the front end. A dc-dc converter is used at the second stage that has a high frequency transformer with multiple secondary windings to obtain different dc voltage levels at the output. The proposed bridgeless converter based power supply is designed using fundamental design equations, and different component values are calculated. Extensive simulations are carried out to demonstrate the improved performance of the proposed bridgeless converter based multi-output computer power supply at varying source voltages and load conditions. Experimental validation of the power supply is carried on a developed hardware prototype, and the test results are compared with the simulated performance for design verification.

  15. Effective switching frequency multiplier inverter

    DOEpatents

    Su, Gui-Jia; Peng, Fang Z.

    2007-08-07

    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.

  16. Emergence of core-peripheries in networks.

    PubMed

    Verma, T; Russmann, F; Araújo, N A M; Nagler, J; Herrmann, H J

    2016-01-29

    A number of important transport networks, such as the airline and trade networks of the world, exhibit a characteristic core-periphery structure, wherein a few nodes are highly interconnected and the rest of the network frays into a tree. Mechanisms underlying the emergence of core-peripheries, however, remain elusive. Here, we demonstrate that a simple pruning process based on removal of underutilized links and redistribution of loads can lead to the emergence of core-peripheries. Links are assumed beneficial if they either carry a sufficiently large load or are essential for global connectivity. This incentivized redistribution process is controlled by a single parameter, which balances connectivity and profit. The obtained networks exhibit a highly resilient and connected core with a frayed periphery. The balanced network shows a higher resilience than the world airline network or the world trade network, revealing a pathway towards robust structural features through pruning.

  17. Emergence of core–peripheries in networks

    PubMed Central

    Verma, T.; Russmann, F.; Araújo, N.A.M.; Nagler, J.; Herrmann, H.J.

    2016-01-01

    A number of important transport networks, such as the airline and trade networks of the world, exhibit a characteristic core–periphery structure, wherein a few nodes are highly interconnected and the rest of the network frays into a tree. Mechanisms underlying the emergence of core–peripheries, however, remain elusive. Here, we demonstrate that a simple pruning process based on removal of underutilized links and redistribution of loads can lead to the emergence of core–peripheries. Links are assumed beneficial if they either carry a sufficiently large load or are essential for global connectivity. This incentivized redistribution process is controlled by a single parameter, which balances connectivity and profit. The obtained networks exhibit a highly resilient and connected core with a frayed periphery. The balanced network shows a higher resilience than the world airline network or the world trade network, revealing a pathway towards robust structural features through pruning. PMID:26822856

  18. Emergence of core-peripheries in networks

    NASA Astrophysics Data System (ADS)

    Verma, T.; Russmann, F.; Araújo, N. A. M.; Nagler, J.; Herrmann, H. J.

    2016-01-01

    A number of important transport networks, such as the airline and trade networks of the world, exhibit a characteristic core-periphery structure, wherein a few nodes are highly interconnected and the rest of the network frays into a tree. Mechanisms underlying the emergence of core-peripheries, however, remain elusive. Here, we demonstrate that a simple pruning process based on removal of underutilized links and redistribution of loads can lead to the emergence of core-peripheries. Links are assumed beneficial if they either carry a sufficiently large load or are essential for global connectivity. This incentivized redistribution process is controlled by a single parameter, which balances connectivity and profit. The obtained networks exhibit a highly resilient and connected core with a frayed periphery. The balanced network shows a higher resilience than the world airline network or the world trade network, revealing a pathway towards robust structural features through pruning.

  19. Statistics for characterizing data on the periphery

    SciTech Connect

    Theiler, James P; Hush, Donald R

    2010-01-01

    We introduce a class of statistics for characterizing the periphery of a distribution, and show that these statistics are particularly valuable for problems in target detection. Because so many detection algorithms are rooted in Gaussian statistics, we concentrate on ellipsoidal models of high-dimensional data distributions (that is to say: covariance matrices), but we recommend several alternatives to the sample covariance matrix that more efficiently model the periphery of a distribution, and can more effectively detect anomalous data samples.

  20. Visualizing Transmedia Networks: Links, Paths and Peripheries

    ERIC Educational Resources Information Center

    Ruppel, Marc Nathaniel

    2012-01-01

    'Visualizing Transmedia Networks: Links, Paths and Peripheries' examines the increasingly complex rhetorical intersections between narrative and media ("old" and "new") in the creation of transmedia fictions, loosely defined as multisensory and multimodal stories told extensively across a diverse media set. In order…

  1. R. S. Peters and the Periphery

    ERIC Educational Resources Information Center

    Haynes, Bruce

    2013-01-01

    Paul Hirst claimed that Richard Peters "revolutionised philosophy of education". This does not accord with my experience in the Antipodean periphery. My experience of the work of Wittgenstein, Austin and Kovesi before reading Peters and Dewey, Kuhn and Toulmin subsequently meant that Peters was a major but not revolutionary figure in my…

  2. An efficient switch-mode power supply using an AC-DC interleaved boost converter and a DC-DC full-bridge topology

    NASA Astrophysics Data System (ADS)

    Lessa Tofoli, Fernando; Gallo, Carlos Alberto

    2011-04-01

    This work presents the conception and analysis of a switch-mode power supply with desirable characteristics of high power factor, low harmonic distortion, regulated output voltage, and high efficiency. An interleaved boost converter associated with a nondissipative snubber is used as a preregulator stage. Additionally, a soft switching full-bridge converter is chosen as DC-DC stage. The combination of both topologies results in the proposed switch-mode power supply. Theoretical background on each one of the converters is presented and analytical results are discussed in order to validate the proposal.

  3. Mathematical Modeling of the Auditory Periphery.

    NASA Astrophysics Data System (ADS)

    Koshigoe, Shozo

    The auditory periphery is conventionally divided into three parts, namely, the outer, middle, and inner ear (or cochlea). Mathematical modeling of the auditory periphery has been used for increasing our understanding of its mechanics via the simulation of experimental results, and for estimating unknown parameters. The various techniques used in this study for modeling the auditory periphery are: (1) Green function methods for investigation of the external ear directional filter functions; (2) finite difference methods in cochlear mechanical model calculations; (3) dispersion relation tests of the consistency of model calculations; (4) dispersion relation checks of experimental cochlear response data for approximate consistency with the implications of causality, linearity, time translation invariance, and minimum phase behavior; (5) dispersion relation tests of the stability of the linear cochlear models with active elements; (6) the introduction of viscosity effects in cochlear mechanics in order to account for data on the low frequency cochlear input impedance; and (7) the incorporation of a non-linear feedback outer-hair-cell model into a cochlear model in order to account for the physiological and psychological data (such as spontaneous and induced acoustic emissions from human ears and their active non-linear interactions with external stimuli).

  4. Potential Role of Acetyl-CoA Synthetase (acs) and Malate Dehydrogenase (mae) in the Evolution of the Acetate Switch in Bacteria and Archaea

    DOE PAGES

    Barnhart, Elliott P.; McClure, Marcella A.; Johnson, Kiki; Cleveland, Sean; Hunt, Kristopher A.; Fields, Matthew W.

    2015-08-03

    Although many Archaea have AMP-Acs (acetyl-coenzyme A synthetase) and ADP-Acs, the extant methanogenic genus Methanosarcina is the only identified Archaeal genus that can utilize acetate via acetate kinase (Ack) and phosphotransacetylase (Pta). Despite the importance of ack as the potential urkinase in the ASKHA phosphotransferase superfamily, an origin hypothesis does not exist for the acetate kinase in Bacteria, Archaea, or Eukarya. Here we demonstrate that Archaeal AMP-Acs and ADP-Acs contain paralogous ATPase motifs previously identified in Ack, which demonstrate a novel relation between these proteins in Archaea. The identification of ATPase motif conservation and resulting structural features in AMP- andmore » ADP-acetyl-CoA synthetase proteins in this study expand the ASKHA superfamily to include acetyl-CoA synthetase. Additional phylogenetic analysis showed that Pta and MaeB sequences had a common ancestor, and that the Pta lineage within the halophilc archaea was an ancestral lineage. Lastly, these results suggested that divergence of a duplicated maeB within an ancient halophilic, archaeal lineage formed a putative pta ancestor. These results provide a potential scenario for the establishment of the Ack/Pta pathway and provide novel insight into the evolution of acetate metabolism for all three domains of life.« less

  5. Potential Role of Acetyl-CoA Synthetase (acs) and Malate Dehydrogenase (mae) in the Evolution of the Acetate Switch in Bacteria and Archaea

    PubMed Central

    Barnhart, Elliott P.; McClure, Marcella A.; Johnson, Kiki; Cleveland, Sean; Hunt, Kristopher A.; Fields, Matthew W.

    2015-01-01

    Although many Archaea have AMP-Acs (acetyl-coenzyme A synthetase) and ADP-Acs, the extant methanogenic genus Methanosarcina is the only identified Archaeal genus that can utilize acetate via acetate kinase (Ack) and phosphotransacetylase (Pta). Despite the importance of ack as the potential urkinase in the ASKHA phosphotransferase superfamily, an origin hypothesis does not exist for the acetate kinase in Bacteria, Archaea, or Eukarya. Here we demonstrate that Archaeal AMP-Acs and ADP-Acs contain paralogous ATPase motifs previously identified in Ack, which demonstrate a novel relation between these proteins in Archaea. The identification of ATPase motif conservation and resulting structural features in AMP- and ADP-acetyl-CoA synthetase proteins in this study expand the ASKHA superfamily to include acetyl-CoA synthetase. Additional phylogenetic analysis showed that Pta and MaeB sequences had a common ancestor, and that the Pta lineage within the halophilc archaea was an ancestral lineage. These results suggested that divergence of a duplicated maeB within an ancient halophilic, archaeal lineage formed a putative pta ancestor. These results provide a potential scenario for the establishment of the Ack/Pta pathway and provide novel insight into the evolution of acetate metabolism for all three domains of life. PMID:26235787

  6. Potential Role of Acetyl-CoA Synthetase (acs) and Malate Dehydrogenase (mae) in the Evolution of the Acetate Switch in Bacteria and Archaea

    SciTech Connect

    Barnhart, Elliott P.; McClure, Marcella A.; Johnson, Kiki; Cleveland, Sean; Hunt, Kristopher A.; Fields, Matthew W.

    2015-08-03

    Although many Archaea have AMP-Acs (acetyl-coenzyme A synthetase) and ADP-Acs, the extant methanogenic genus Methanosarcina is the only identified Archaeal genus that can utilize acetate via acetate kinase (Ack) and phosphotransacetylase (Pta). Despite the importance of ack as the potential urkinase in the ASKHA phosphotransferase superfamily, an origin hypothesis does not exist for the acetate kinase in Bacteria, Archaea, or Eukarya. Here we demonstrate that Archaeal AMP-Acs and ADP-Acs contain paralogous ATPase motifs previously identified in Ack, which demonstrate a novel relation between these proteins in Archaea. The identification of ATPase motif conservation and resulting structural features in AMP- and ADP-acetyl-CoA synthetase proteins in this study expand the ASKHA superfamily to include acetyl-CoA synthetase. Additional phylogenetic analysis showed that Pta and MaeB sequences had a common ancestor, and that the Pta lineage within the halophilc archaea was an ancestral lineage. Lastly, these results suggested that divergence of a duplicated maeB within an ancient halophilic, archaeal lineage formed a putative pta ancestor. These results provide a potential scenario for the establishment of the Ack/Pta pathway and provide novel insight into the evolution of acetate metabolism for all three domains of life.

  7. Operation Method for AC Motor Control during Power Interruption in Direct AC/AC Converter System

    NASA Astrophysics Data System (ADS)

    Shizu, Keiichiro; Azuma, Satoshi

    Direct AC/AC converters have been studied due to their potential use in power converters with no DC-link capacitor, which can contribute to the miniaturization of power converters. However, the absence of a DC-link capacitor makes it difficult to control the AC motor during power interruption. First, this paper proposes a system that realizes AC motor control during power interruption by utilizing a clamp capacitor. In general, direct AC/AC converters have a clamp circuit consisting of a rectifier diode(s) and a clamp capacitor in order to avoid over-voltages. In the proposed system, there is an additional semiconductor switch reverse-parallel to the rectifier diode(s), and the clamp capacitor voltage can be utilized for AC motor control by turning on the additional switch. Second, this paper discusses an operation method for AC motor control and clamp capacitor voltage control during power interruption. In the proposed method “DC-link voltage control”, the kinetic energy in the AC motor is transformed into electrical energy and stored in the clamp capacitor; the clamp capacitor is therefore charged and the capacitor voltage is controlled to remain constant at an instruction value. Third, this paper discusses a switching operation during power interruption. A dead-time is introduced between the operation of turning off all switches on the rectifier side and the operation of turning on the additional switch, which prevents the occurrence of a short circuit between the interrupted power source and the clamp capacitor. Finally, experimental results are presented. During power interruptions, an output current was continuously obtained and the clamp capacitor voltage was maintained to be equal to the instruction value of the capacitor voltage. These results indicate that both AC motor control and capacitor voltage control were successfully achieved by using the proposed system.

  8. ac bidirectional motor controller

    NASA Technical Reports Server (NTRS)

    Schreiner, K.

    1988-01-01

    Test data are presented and the design of a high-efficiency motor/generator controller at NASA-Lewis for use with the Space Station power system testbed is described. The bidirectional motor driver is a 20 kHz to variable frequency three-phase ac converter that operates from the high-frequency ac bus being designed for the Space Station. A zero-voltage-switching pulse-density-modulation technique is used in the converter to shape the low-frequency output waveform.

  9. Dynamical feature extraction at the sensory periphery guides chemotaxis

    PubMed Central

    Schulze, Aljoscha; Gomez-Marin, Alex; Rajendran, Vani G; Lott, Gus; Musy, Marco; Ahammad, Parvez; Deogade, Ajinkya; Sharpe, James; Riedl, Julia; Jarriault, David; Trautman, Eric T; Werner, Christopher; Venkadesan, Madhusudhan; Druckmann, Shaul; Jayaraman, Vivek; Louis, Matthieu

    2015-01-01

    Behavioral strategies employed for chemotaxis have been described across phyla, but the sensorimotor basis of this phenomenon has seldom been studied in naturalistic contexts. Here, we examine how signals experienced during free olfactory behaviors are processed by first-order olfactory sensory neurons (OSNs) of the Drosophila larva. We find that OSNs can act as differentiators that transiently normalize stimulus intensity—a property potentially derived from a combination of integral feedback and feed-forward regulation of olfactory transduction. In olfactory virtual reality experiments, we report that high activity levels of the OSN suppress turning, whereas low activity levels facilitate turning. Using a generalized linear model, we explain how peripheral encoding of olfactory stimuli modulates the probability of switching from a run to a turn. Our work clarifies the link between computations carried out at the sensory periphery and action selection underlying navigation in odor gradients. DOI: http://dx.doi.org/10.7554/eLife.06694.001 PMID:26077825

  10. Learning English in the Periphery: A View from Myanmar (Burma)

    ERIC Educational Resources Information Center

    Tin, Tan Bee

    2014-01-01

    Although researchers have called for the investigation of local vernacular learning and teaching practices in various ELT (English language teaching) contexts, studies conducted in the Periphery are fewer in number. This study attempts to understand English learning experiences of a group of students from the Periphery, who were studying English…

  11. MOS-transistor power switches

    NASA Astrophysics Data System (ADS)

    Konev, Iu. I.; Mashukov, E. V.

    The output characteristics of vertical-channel MOS power transistors are analyzed. It is shown that it is possible to remove the basic energy and weight-volume constraints associated with the nonlinearity of the characeristics of devices with carrier injection (i.e., diodes, transistors, and thyristors). This makes it possible to increase the specific power of all types of power switches. The discussion covers switches for ac and dc power circuits, low-voltage rectifiers, and switches with pulse width modulation.

  12. Study of switching transients in high frequency converters

    NASA Technical Reports Server (NTRS)

    Zinger, Donald S.; Elbuluk, Malik E.; Lee, Tony

    1993-01-01

    As the semiconductor technologies progress rapidly, the power densities and switching frequencies of many power devices are improved. With the existing technology, high frequency power systems become possible. Use of such a system is advantageous in many aspects. A high frequency ac source is used as the direct input to an ac/ac pulse-density-modulation (PDM) converter. This converter is a new concept which employs zero voltage switching techniques. However, the development of this converter is still in its infancy stage. There are problems associated with this converter such as a high on-voltage drop, switching transients, and zero-crossing detecting. Considering these problems, the switching speed and power handling capabilities of the MOS-Controlled Thyristor (MCT) makes the device the most promising candidate for this application. A complete insight of component considerations for building an ac/ac PDM converter for a high frequency power system is addressed. A power device review is first presented. The ac/ac PDM converter requires switches that can conduct bi-directional current and block bi-directional voltage. These bi-directional switches can be constructed using existing power devices. Different bi-directional switches for the converter are investigated. Detailed experimental studies of the characteristics of the MCT under hard switching and zero-voltage switching are also presented. One disadvantage of an ac/ac converter is that turn-on and turn-off of the switches has to be completed instantaneously when the ac source is at zero voltage. Otherwise shoot-through current or voltage spikes can occur which can be hazardous to the devices. In order for the devices to switch softly in the safe operating area even under non-ideal cases, a unique snubber circuit is used in each bi-directional switch. Detailed theory and experimental results for circuits using these snubbers are presented. A current regulated ac/ac PDM converter built using MCT's and IGBT's is

  13. Power Switching Device

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The MOS-Controlled Thyristor is a new type of power switching device for faster and more efficient control and management of power electronics. It enables power electronic switching at frequencies of 50 to 100 thousand times a second with much lower power losses than other semiconductor devices. Advantages include electric power savings and smaller space. The device is used in motor and power controllers, AC & DC motor drives and induction heating. Early development was supported by Lewis Research Center (LEW) and other agencies. General Electric''s power semiconductor operation, the initial NASA contractor, was later purchased by Harris Semiconductor.

  14. Characterization and snubbing of a bidirectional MCT in a resonant ac link converter

    NASA Technical Reports Server (NTRS)

    Lee, Tony; Elbuluk, Malik E.; Zinger, Donald S.

    1993-01-01

    The MOS-Controlled Thyristor (MCT) is emerging as a powerful switch that combines the better characteristics of existing power devices. A study of switching stresses on an MCT switch under zero voltage resonant switching is presented. The MCT is used as a bidirectional switch in an ac/ac pulse density modulated inverter for induction motor drive. Current and voltage spikes are observed and analyzed with variations in the timing of the switching. Different snubber circuit configurations are under investigation to minimize the effect of these transients. The results will be extended to study and test the MCT switching in a medium power (5 hp) induction motor drive.

  15. Macedonian Direct Objects, Clitics and the Left Periphery

    ERIC Educational Resources Information Center

    Kochovska, Slavica

    2010-01-01

    This dissertation investigates the patterning of Macedonian direct object DPs with respect to clitic pronouns. The occurrence of clitics with direct objects in Macedonian varies along two dimensions, the type of DP and the position of DP. Two broad classes are considered, regular and wh DPs, and positions both within IP and at the left periphery.…

  16. UPS with input commutation between ac and dc sources of power

    SciTech Connect

    Severinsky, A.J.

    1993-08-31

    An uninterruptible power supply is described, said power supply comprising: AC input terminal means for receiving a first AC voltage from an AC power source; DC input terminal means for receiving a first DC voltage from a DC power source; AC output terminal means for connecting to a load; converter means for converting said first AC voltage to a second DC voltage across electrical charge storage means coupled to said converter means, said second DC voltage being larger than the maximum peak voltage of said first AC voltage and said first DC voltage; switching means coupled to said AC power source and said DC power source for selectively connecting said AC power source or said DC power source to said converter means; inverter means coupled to said electrical charge storage means for receiving said second DC voltage and inverting said second DC voltage to a second AC voltage, said second AC voltage being coupled to said AC output terminal means; and control means coupled to said switching means for controlling the operation of said switching means, said control means operating said switching means to connect said AC power source to said converter means only when said first AC voltage is within a predetermined range and operating to connect said DC power source to said converter means when said first AC voltage is outside of said range.

  17. Switch wear leveling

    SciTech Connect

    Wu, Hunter; Sealy, Kylee; Gilchrist, Aaron

    2015-09-01

    An apparatus for switch wear leveling includes a switching module that controls switching for two or more pairs of switches in a switching power converter. The switching module controls switches based on a duty cycle control technique and closes and opens each switch in a switching sequence. The pairs of switches connect to a positive and negative terminal of a DC voltage source. For a first switching sequence a first switch of a pair of switches has a higher switching power loss than a second switch of the pair of switches. The apparatus includes a switch rotation module that changes the switching sequence of the two or more pairs of switches from the first switching sequence to a second switching sequence. The second switch of a pair of switches has a higher switching power loss than the first switch of the pair of switches during the second switching sequence.

  18. Dynamics of the periphery current in Rhode Island Sound

    NASA Astrophysics Data System (ADS)

    Liu, Qianqian; Rothstein, Lewis M.; Luo, Yiyong; Ullman, David S.; Codiga, Daniel L.

    2016-09-01

    Observations reveal a near-surface circulation around the periphery of Rhode Island Sound (RIS) that occurs in summer stratified conditions and disappears in winter when weak solar insolation and wind stirring result in strong vertical mixing. According to a series of numerical simulations and theoretical analysis, we attribute the summer intensification of this "periphery current" to a circulation produced by seasonal bottom thermal fronts often observed from May to September. The strength of the thermal fronts is proportional to the surface solar radiation. Meanwhile, the simulations capture a continuous topographically rectified tidal residual current in RIS and a pair of opposite-sign headland eddies around Montauk Point in Block Island Sound (BIS). Our analysis suggests the importance of nonlinear vorticity advection and frictional torques in BIS. On the other hand, the vorticity balance shows the importance of velocity torque by contributing to the opposite headland gyres, while the effect by planetary vorticity stretching is negligible over BIS but important in RIS.

  19. Disentangling bipartite and core-periphery structure in financial networks

    NASA Astrophysics Data System (ADS)

    Barucca, Paolo; Lillo, Fabrizio

    2016-07-01

    A growing number of systems are represented as networks whose architecture conveys significant information and determines many of their properties. Examples of network architecture include modular, bipartite, and core-periphery structures. However inferring the network structure is a non trivial task and can depend sometimes on the chosen null model. Here we propose a method for classifying network structures and ranking its nodes in a statistically well-grounded fashion. The method is based on the use of Belief Propagation for learning through Entropy Maximization on both the Stochastic Block Model (SBM) and the degree-corrected Stochastic Block Model (dcSBM). As a specific application we show how the combined use of the two ensembles -SBM and dcSBM- allows to disentangle the bipartite and the core-periphery structure in the case of the e-MID interbank network. Specifically we find that, taking into account the degree, this interbank network is better described by a bipartite structure, while using the SBM the core-periphery structure emerges only when data are aggregated for more than a week.

  20. The importance of loading the periphery of the vertebral endplate

    PubMed Central

    Sutterlin, Chester; Dabirrahmani, Danè; Appleyard, Richard

    2016-01-01

    Background Commercial fusion cages typically provide support in the central region of the endplate, failing to utilize the increased compressive strength around the periphery. This study demonstrates the increase in compressive strength that can be achieved if the bony periphery of the endplate is loaded. Methods Sixteen cadaveric lumbar vertebrae (L1–L5) were randomly divided into two even groups. A different commercial mass produced implant (MPI) was allocated to each group: (I) a Polyether-ether-ketone (PEEK) anterior lumber inter-body fusion (ALIF) MPI; and (II) a titanium ALIF MPI. Uniaxial compression at a displacement rate of 0.5 mm/sec was applied to all vertebrae during two phases: (I) with the allocated MPI situated in the central region of the endplate; (II) with an aluminum plate, designed to load the bony periphery of the endplate. The failure load and mode of failure was recorded. Results From phase 1 to phase 2, the failure load increased from 1.1±0.4 to 2.9±1.4 kN for group 1; and from 1.3±1.0 to 3.0±1.9 kN for group 2. The increase in strength from phase 1 to phase 2 was statistically significant for each group (group 1: P<0.01, group 2: P<0.05, paired t-test). There was no significant difference between the groups in either phase (P>0.05, t-test). The mode of failure in phase 1 was the implant being forced through the endplate for both groups. In phase 2, the mode of failure was either a fracture of the epiphyseal rim or buckling of the side wall of the vertebral body. Conclusions Loading the periphery of the vertebral endplate achieved significant increase in compressive load capacity compared to loading the central region of the endplate. Clinically, this implies that patient-specific implants which load the periphery of the vertebral endplate could decrease the incidence of subsidence and improve surgical outcomes. PMID:27757430

  1. Trapping of Rb Atoms by ac Electric Fields

    SciTech Connect

    Schlunk, Sophie; Marian, Adela; Geng, Peter; Meijer, Gerard; Schoellkopf, Wieland; Mosk, Allard P.

    2007-06-01

    We demonstrate trapping of an ultracold gas of neutral atoms in a macroscopic ac electric trap. Three-dimensional confinement is obtained by switching between two saddle-point configurations of the electric field. Stable trapping is observed in a narrow range of switching frequencies around 60 Hz. The dynamic confinement of the atoms is directly visualized at different phases of the ac switching cycle. We observe about 10{sup 5} Rb atoms in the 1 mm{sup 3} large and several microkelvins deep trap with a lifetime of approximately 5 s.

  2. Optical switches and switching methods

    SciTech Connect

    Doty, Michael

    2008-03-04

    A device and method for collecting subject responses, particularly during magnetic imaging experiments and testing using a method such as functional MRI. The device comprises a non-metallic input device which is coupled via fiber optic cables to a computer or other data collection device. One or more optical switches transmit the subject's responses. The input device keeps the subject's fingers comfortably aligned with the switches by partially immobilizing the forearm, wrist, and/or hand of the subject. Also a robust nonmetallic switch, particularly for use with the input device and methods for optical switching.

  3. A switched catalysis qualified sealers capped one-step synthesis biocompatibility bimetallic scaffold film for Neu5Acα(2-6)Gal β MP Glycoside specific detection.

    PubMed

    Xia, Chunyong; He, Junlin; Yuan, Guolin; Li, Yuliang; Li, Qingying; Yu, Chao

    2016-03-15

    In this work, a novel label-free biosensor was designed for the sensitive and selective determination of Neu5Acα(2-6)Gal β MP Glycoside using AuPt-PPy(polypyrrole) conductive nanocomposite film as the sensor platform. The introduced AuPt-PPy nanocomposite provided a large surface area for the immobilization of Sambucus nigra agglutinis (SNA) through a coupling agent for specifically recognizing analytes and exhibited high electrocatalytic activity toward the reduction of hydrogen peroxide (H2O2) as an analytical signal. Subsequently, to block the non-specific sites of the modified electrode, GOx was employed instead of the usual sealers. Most importantly, in the presence of glucose, these localized GOx further enhanced the electrochemical signal, which was achieved by the efficient catalysis of glucose. This study is the first that demonstrates the specific detection of Neu5Acα(2-6)Gal β MP Glycoside using AuPt-PPy as the electrocatalytic. Under optimal conditions, the electrochemical biosensor exhibited a wide linear range of 0.01 pgmL(-1)-800 ngmL(-1) with a low detection limit of 0.003 pgmL(-1) (S/N=3), due to the affinity between SNA and Neu5Acα(2-6)Gal β MP Glycoside. Therefore, the co-catalysis signal amplification approach has considerable potential in clinical applications and is suitable for the quantification of other biomarkers. PMID:26516685

  4. A switched catalysis qualified sealers capped one-step synthesis biocompatibility bimetallic scaffold film for Neu5Acα(2-6)Gal β MP Glycoside specific detection.

    PubMed

    Xia, Chunyong; He, Junlin; Yuan, Guolin; Li, Yuliang; Li, Qingying; Yu, Chao

    2016-03-15

    In this work, a novel label-free biosensor was designed for the sensitive and selective determination of Neu5Acα(2-6)Gal β MP Glycoside using AuPt-PPy(polypyrrole) conductive nanocomposite film as the sensor platform. The introduced AuPt-PPy nanocomposite provided a large surface area for the immobilization of Sambucus nigra agglutinis (SNA) through a coupling agent for specifically recognizing analytes and exhibited high electrocatalytic activity toward the reduction of hydrogen peroxide (H2O2) as an analytical signal. Subsequently, to block the non-specific sites of the modified electrode, GOx was employed instead of the usual sealers. Most importantly, in the presence of glucose, these localized GOx further enhanced the electrochemical signal, which was achieved by the efficient catalysis of glucose. This study is the first that demonstrates the specific detection of Neu5Acα(2-6)Gal β MP Glycoside using AuPt-PPy as the electrocatalytic. Under optimal conditions, the electrochemical biosensor exhibited a wide linear range of 0.01 pgmL(-1)-800 ngmL(-1) with a low detection limit of 0.003 pgmL(-1) (S/N=3), due to the affinity between SNA and Neu5Acα(2-6)Gal β MP Glycoside. Therefore, the co-catalysis signal amplification approach has considerable potential in clinical applications and is suitable for the quantification of other biomarkers.

  5. Crowding deficits in the visual periphery of schizophrenia patients.

    PubMed

    Kraehenmann, Rainer; Vollenweider, Franz X; Seifritz, Erich; Kometer, Michael

    2012-01-01

    Accumulating evidence suggests that basic visual information processing is impaired in schizophrenia. However, deficits in peripheral vision remain largely unexplored. Here we hypothesized that sensory processing of information in the visual periphery would be impaired in schizophrenia patients and, as a result, crowding - the breakdown in target recognition that occurs in cluttered visual environments - would be stronger. Therefore, we assessed visual crowding in the peripheral vision of schizophrenia patients and healthy controls. Subjects were asked to identify a target letter that was surrounded by distracter letters of similar appearance. Targets and distracters were displayed at 8° and 10° of visual angle from the fixation point (eccentricity), and target-distracter spacing was 2°, 3°, 4°, 5°, 6°, 7° or 8° of visual angle. Eccentricity and target-distracter spacing were randomly varied. Accuracy was defined as the proportion of correctly identified targets. Critical spacing was defined as the spacing at which target identification accuracy began to deteriorate, and was assessed at viewing eccentricities of 8° and 10°. Schizophrenia patients were less accurate and showed a larger critical spacing than healthy individuals. These results indicate that crowding is stronger and sensory processing of information in the visual periphery is impaired in schizophrenia. This is in line with previous reports of preferential magnocellular dysfunction in schizophrenia. Thus, deficits in peripheral vision may account for perceptual alterations and contribute to cognitive dysfunction in schizophrenia.

  6. ION SWITCH

    DOEpatents

    Cook, B.

    1959-02-10

    An ion switch capable of transferring large magnitudes of power is described. An ion switch constructed in accordance with the invention includes a pair of spaced control electrodes disposed in a highly evacuated region for connection in a conventional circuit to control the passing of power therethrough. A controllable ionic conduction path is provided directiy between the control electrodes by a source unit to close the ion switch. Conventional power supply means are provided to trigger the source unit and control the magnitude, durations and pulse repetition rate of the aforementioned ionic conduction path.

  7. Strategies to regulate transcription factor–mediated gene positioning and interchromosomal clustering at the nuclear periphery

    PubMed Central

    Randise-Hinchliff, Carlo; Coukos, Robert; Sood, Varun; Sumner, Michael Chas; Zdraljevic, Stefan; Meldi Sholl, Lauren; Garvey Brickner, Donna; Ahmed, Sara; Watchmaker, Lauren

    2016-01-01

    In budding yeast, targeting of active genes to the nuclear pore complex (NPC) and interchromosomal clustering is mediated by transcription factor (TF) binding sites in the gene promoters. For example, the binding sites for the TFs Put3, Ste12, and Gcn4 are necessary and sufficient to promote positioning at the nuclear periphery and interchromosomal clustering. However, in all three cases, gene positioning and interchromosomal clustering are regulated. Under uninducing conditions, local recruitment of the Rpd3(L) histone deacetylase by transcriptional repressors blocks Put3 DNA binding. This is a general function of yeast repressors: 16 of 21 repressors blocked Put3-mediated subnuclear positioning; 11 of these required Rpd3. In contrast, Ste12-mediated gene positioning is regulated independently of DNA binding by mitogen-activated protein kinase phosphorylation of the Dig2 inhibitor, and Gcn4-dependent targeting is up-regulated by increasing Gcn4 protein levels. These different regulatory strategies provide either qualitative switch-like control or quantitative control of gene positioning over different time scales. PMID:26953353

  8. Electromechanical switch

    NASA Astrophysics Data System (ADS)

    Antonuzzi, Anthony P.; Carignan, Donald J.

    1986-06-01

    A hardened electromechanical switch is disclosed. When appropriate electrical contacts and pick-offs are aligned, four switches close. The possible number of switch combinations selectable are 4095 based upon a base eight counting system. The switch has a counter section and a memory section. The counter section uses an odometer like device based upon octal. Each counter wheel of the counter section has an electrical pick-off that interacts with the memory section. In the memory section, a plurality of octal numbers, four, are entered into and locked thereon such that each counter set disk, four, therein has one octal number thereon. Electrical contacts are placed on the counter set disks of the memory section and these touch the pick-offs of the counter wheels which will simultaneously close on the four contacts of the counter set disk in only one of the 4095 combinations noted above.

  9. Acceleration switch

    DOEpatents

    Abbin, J.P. Jr.; Devaney, H.F.; Hake, L.W.

    1979-08-29

    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.

  10. Acceleration switch

    DOEpatents

    Abbin, Jr., Joseph P.; Devaney, Howard F.; Hake, Lewis W.

    1982-08-17

    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.

  11. Ladder contours are undetectable in the periphery: a crowding effect?

    PubMed

    May, Keith A; Hess, Robert F

    2007-10-29

    We studied the perceptual integration of contours consisting of Gabor elements positioned along a smooth path, embedded among distractor elements. Contour elements either formed tangents to the path ("snakes") or were perpendicular to it ("ladders"). Perfectly straight snakes and ladders were easily detected in the fovea but, at an eccentricity of 6 degrees , only the snakes were detectable. The disproportionate impairment of peripheral ladder detection remained when we brought foveal performance away from ceiling by jittering the orientations of the elements. We propose that the failure to detect peripheral ladders is a form of crowding, the phenomenon observed when identification of peripherally located letters is disrupted by flanking letters. D. G. Pelli, M. Palomares, and N. J. Majaj (2004) outlined a model in which simple feature detectors are followed by integration fields, which are involved in tasks, such as letter identification, that require the outputs of several detectors. They proposed that crowding occurs because small integration fields are absent from the periphery, leading to inappropriate feature integration by large peripheral integration fields. We argue that the "association field," which has been proposed to mediate contour integration (D. J. Field, A. Hayes, & R. F. Hess, 1993), is a type of integration field. Our data are explained by an elaboration of Pelli et al.'s model, in which weak ladder integration competes with strong snake integration. In the fovea, the association fields were small, and the model integrated snakes and ladders with little interference. In the periphery, the association fields were large, and integration of ladders was severely disrupted by interference from spurious snake contours. In contrast, the model easily detected snake contours in the periphery. In a further demonstration of the possible link between contour integration and crowding, we ran our contour integration model on groups of three-letter stimuli

  12. The Critical Periphery in the Growth of Social Protests

    PubMed Central

    Barberá, Pablo; Wang, Ning; Bonneau, Richard; Jost, John T.; Nagler, Jonathan; Tucker, Joshua; González-Bailón, Sandra

    2015-01-01

    Social media have provided instrumental means of communication in many recent political protests. The efficiency of online networks in disseminating timely information has been praised by many commentators; at the same time, users are often derided as “slacktivists” because of the shallow commitment involved in clicking a forwarding button. Here we consider the role of these peripheral online participants, the immense majority of users who surround the small epicenter of protests, representing layers of diminishing online activity around the committed minority. We analyze three datasets tracking protest communication in different languages and political contexts through the social media platform Twitter and employ a network decomposition technique to examine their hierarchical structure. We provide consistent evidence that peripheral participants are critical in increasing the reach of protest messages and generating online content at levels that are comparable to core participants. Although committed minorities may constitute the heart of protest movements, our results suggest that their success in maximizing the number of online citizens exposed to protest messages depends, at least in part, on activating the critical periphery. Peripheral users are less active on a per capita basis, but their power lies in their numbers: their aggregate contribution to the spread of protest messages is comparable in magnitude to that of core participants. An analysis of two other datasets unrelated to mass protests strengthens our interpretation that core-periphery dynamics are characteristically important in the context of collective action events. Theoretical models of diffusion in social networks would benefit from increased attention to the role of peripheral nodes in the propagation of information and behavior. PMID:26618352

  13. The Critical Periphery in the Growth of Social Protests.

    PubMed

    Barberá, Pablo; Wang, Ning; Bonneau, Richard; Jost, John T; Nagler, Jonathan; Tucker, Joshua; González-Bailón, Sandra

    2015-01-01

    Social media have provided instrumental means of communication in many recent political protests. The efficiency of online networks in disseminating timely information has been praised by many commentators; at the same time, users are often derided as "slacktivists" because of the shallow commitment involved in clicking a forwarding button. Here we consider the role of these peripheral online participants, the immense majority of users who surround the small epicenter of protests, representing layers of diminishing online activity around the committed minority. We analyze three datasets tracking protest communication in different languages and political contexts through the social media platform Twitter and employ a network decomposition technique to examine their hierarchical structure. We provide consistent evidence that peripheral participants are critical in increasing the reach of protest messages and generating online content at levels that are comparable to core participants. Although committed minorities may constitute the heart of protest movements, our results suggest that their success in maximizing the number of online citizens exposed to protest messages depends, at least in part, on activating the critical periphery. Peripheral users are less active on a per capita basis, but their power lies in their numbers: their aggregate contribution to the spread of protest messages is comparable in magnitude to that of core participants. An analysis of two other datasets unrelated to mass protests strengthens our interpretation that core-periphery dynamics are characteristically important in the context of collective action events. Theoretical models of diffusion in social networks would benefit from increased attention to the role of peripheral nodes in the propagation of information and behavior. PMID:26618352

  14. The Critical Periphery in the Growth of Social Protests.

    PubMed

    Barberá, Pablo; Wang, Ning; Bonneau, Richard; Jost, John T; Nagler, Jonathan; Tucker, Joshua; González-Bailón, Sandra

    2015-01-01

    Social media have provided instrumental means of communication in many recent political protests. The efficiency of online networks in disseminating timely information has been praised by many commentators; at the same time, users are often derided as "slacktivists" because of the shallow commitment involved in clicking a forwarding button. Here we consider the role of these peripheral online participants, the immense majority of users who surround the small epicenter of protests, representing layers of diminishing online activity around the committed minority. We analyze three datasets tracking protest communication in different languages and political contexts through the social media platform Twitter and employ a network decomposition technique to examine their hierarchical structure. We provide consistent evidence that peripheral participants are critical in increasing the reach of protest messages and generating online content at levels that are comparable to core participants. Although committed minorities may constitute the heart of protest movements, our results suggest that their success in maximizing the number of online citizens exposed to protest messages depends, at least in part, on activating the critical periphery. Peripheral users are less active on a per capita basis, but their power lies in their numbers: their aggregate contribution to the spread of protest messages is comparable in magnitude to that of core participants. An analysis of two other datasets unrelated to mass protests strengthens our interpretation that core-periphery dynamics are characteristically important in the context of collective action events. Theoretical models of diffusion in social networks would benefit from increased attention to the role of peripheral nodes in the propagation of information and behavior.

  15. Pointing in visual periphery: is DF's dorsal stream intact?

    PubMed

    Hesse, Constanze; Ball, Keira; Schenk, Thomas

    2014-01-01

    Observations of the visual form agnosic patient DF have been highly influential in establishing the hypothesis that separate processing streams deal with vision for perception (ventral stream) and vision for action (dorsal stream). In this context, DF's preserved ability to perform visually-guided actions has been contrasted with the selective impairment of visuomotor performance in optic ataxia patients suffering from damage to dorsal stream areas. However, the recent finding that DF shows a thinning of the grey matter in the dorsal stream regions of both hemispheres in combination with the observation that her right-handed movements are impaired when they are performed in visual periphery has opened up the possibility that patient DF may potentially also be suffering from optic ataxia. If lesions to the posterior parietal cortex (dorsal stream) are bilateral, pointing and reaching deficits should be observed in both visual hemifields and for both hands when targets are viewed in visual periphery. Here, we tested DF's visuomotor performance when pointing with her left and her right hand toward targets presented in the left and the right visual field at three different visual eccentricities. Our results indicate that DF shows large and consistent impairments in all conditions. These findings imply that DF's dorsal stream atrophies are functionally relevant and hence challenge the idea that patient DF's seemingly normal visuomotor behaviour can be attributed to her intact dorsal stream. Instead, DF seems to be a patient who suffers from combined ventral and dorsal stream damage meaning that a new account is needed to explain why she shows such remarkably normal visuomotor behaviour in a number of tasks and conditions. PMID:24626162

  16. On lossless switched-capacitor power converters

    SciTech Connect

    Tse, C.K.; Wong, S.C.; Chow, M.H.L.

    1995-05-01

    This paper addresses the design of efficient switched-capacitor power converters. The discussion starts with a review of the fundamental limitation of switched-capacitor circuits which shows that the topology of such circuits and the ``forced`` step changes of capacitor voltages are the inherent attributes of power loss. Although the argument follows from a rather trivial result from basic circuit theory, it addresses an important issue on the maximum efficiency achievable in a switched-capacitor converter circuit. Based on the observed topological constraint of switched-capacitor converter circuits, the simplest lossless topology for AC/DC conversion is deduced. Also discussed is a simple version of lossless topology that achieves isolation between the source and the load. Finally, an experimental AC/DC switched-capacitor converter, based on the proposed idea, is presented which demonstrates an improved efficiency over other existing switched-capacitor converters. The proposed AC/DC converter contains no inductors and thus is suitable for custom IC implementation for very low power applications.

  17. System and method for determining stator winding resistance in an AC motor

    DOEpatents

    Lu, Bin; Habetler, Thomas G.; Zhang, Pinjia; Theisen, Peter J.

    2011-05-31

    A system and method for determining stator winding resistance in an AC motor is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of an AC motor. The circuit includes at least one contactor and at least one switch to control current flow and terminal voltages in the AC motor. The system also includes a controller connected to the circuit and configured to modify a switching time of the at least one switch to create a DC component in an output of the system corresponding to an input to the AC motor and determine a stator winding resistance of the AC motor based on the injected DC component of the voltage and current.

  18. Optical switch

    DOEpatents

    Reedy, Robert P.

    1987-01-01

    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.

  19. Switching Transistor

    NASA Astrophysics Data System (ADS)

    1981-01-01

    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.

  20. [Vascular networks of the periphery of the finger nail].

    PubMed

    Sick, H; Wolfram-Gabel, R

    The vascular networks of the periphery of the nail of the finger are studied on fingers of adults, fetus and newborns, by injecting the vascular system with gelatinous Indian ink. The nail is an avascular horny structure, partially covered with the nail fold. It is lying on a nail bed which prolonges forwards with the hyponychium. Each part of the nail apparatus (nail fold, matricial and unmatricial parts of the nail bed, hyponychium) presents a characteristic network which is tributary of dorsal collaterals arising from the digital palmar vessels and from their arcades. These networks are papillar, pseudopapillar, reticular and subdermical. The morphology and density of these networks vary according to their localisation and are superimposed with the histological variations of the different parts of the nail apparatus. Thus the matricial part of the nail bed shows a poor vascularization. It corresponds to the germinative part of the nail and is responsible of the color of the lunula. The unmatricial part of the nail bed and the hyponychium have dense vascular networks with glomi.

  1. Asymmetric Switching For A PWM H-Bridge Power Circuit

    NASA Technical Reports Server (NTRS)

    Wong, See-Pok

    1995-01-01

    Only two of four switches interrupt substantial current. An asymmetric timing scheme improves design and operation of pulse-width-modulation (PWM) H-bridge switch-and-transformer circuit. Circuit part of dc-to-dc converter or dc-to-ac inverter; in either case, output current or voltage regulated by adjusting times of opening and closing of semiconductor switches 1 through 4 to adjust durations of current pulses in primary winding of transformer.

  2. System and method for determining stator winding resistance in an AC motor using motor drives

    DOEpatents

    Lu, Bin; Habetler, Thomas G; Zhang, Pinjia

    2013-02-26

    A system and method for determining the stator winding resistance of AC motors is provided. The system includes an AC motor drive having an input connectable to an AC source and an output connectable to an input terminal of an AC motor, a pulse width modulation (PWM) converter having switches therein to control current flow and terminal voltages in the AC motor, and a control system connected to the PWM converter. The control system generates a command signal to cause the PWM converter to control an output of the AC motor drive corresponding to an input to the AC motor, selectively generates a modified command signal to cause the PWM converter to inject a DC signal into the output of the AC motor drive, and determines a stator winding resistance of the AC motor based on the DC signal of at least one of the voltage and current.

  3. Alternator-driven, magnetically switched modulator

    NASA Astrophysics Data System (ADS)

    Kihara, R.; Kirbie, H. C.

    The technique of magnetically switching high-power pulses was recently revitalized with the development of amorphous magnetic alloys and the new power conditioning requirements of pulsed lasers and high-brightness particle accelerators. The most common magnetic switching technique for generating high-repetition-rate pulses consists of a dc power supply, a triggered switch (thyratron or solid-state), and a repeated network of magnetic switches and capacitors. The life of this type of pulser is limited by the aging of liquid and solid dielectric materials and by the reliability of the triggered switch. An alternator-driven, magnetically switched modulator differs from the conventional magnetic modulator in the replacement of the dc power supply and triggered switch with a high-frequency motor-generator set and an all-magnetic circuit. The power conditioning network converts each cycle of the applied ac power into a single, compressed, unipolar pulse. Consequently, the modulator produces a train of pulses with an interpulse separation equal to the period of the alternator. Additional compression can be attained by the addition of successive stages of magnetic switching. The absence of active switches within the network improves the system reliability and extends the service life of the modulator to the limits of component insulation fatigue and alternator bearing wear. This style of magnetic pulse compression was first described by Melville and reproduced at LLNL in order to quantify the network efficiency, jitter and reliability when modern magnetic materials are employed.

  4. Transport of cargo from periphery to brain by circulating monocytes.

    PubMed

    Cintron, Amarallys F; Dalal, Nirjari V; Dooyema, Jeromy; Betarbet, Ranjita; Walker, Lary C

    2015-10-01

    The misfolding and aggregation of the Aβ peptide - a fundamental event in the pathogenesis of Alzheimer׳s disease - can be instigated in the brains of experimental animals by the intracranial infusion of brain extracts that are rich in aggregated Aβ. Recent experiments have found that the peripheral (intraperitoneal) injection of Aβ seeds induces Aβ deposition in the brains of APP-transgenic mice, largely in the form of cerebral amyloid angiopathy. Macrophage-type cells normally are involved in pathogen neutralization and antigen presentation, but under some circumstances, circulating monocytes have been found to act as vectors for the transport of pathogenic agents such as viruses and prions. The present study assessed the ability of peripheral monocytes to transport Aβ aggregates from the peritoneal cavity to the brain. Our initial experiments showed that intravenously delivered macrophages that had previously ingested fluorescent nanobeads as tracers migrate primarily to peripheral organs such as spleen and liver, but that a small number also reach the brain parenchyma. We next injected CD45.1-expressing monocytes from donor mice intravenously into CD45.2-expressing host mice; after 24h, analysis by fluorescence-activated cell sorting (FACS) and histology confirmed that some CD45.1 monocytes enter the brain, particularly in the superficial cortex and around blood vessels. When the donor monocytes are first exposed to Aβ-rich brain extracts from human AD cases, a subset of intravenously delivered Aβ-containing cells migrate to the brain. These experiments indicate that, in mouse models, circulating monocytes are potential vectors by which exogenously delivered, aggregated Aβ travels from periphery to brain, and more generally support the hypothesis that macrophage-type cells can participate in the dissemination of proteopathic seeds. PMID:26168900

  5. Transport of Cargo from Periphery to Brain by Circulating Monocytes

    PubMed Central

    Cintron, Amarallys F.; Dalal, Nirjari V.; Dooyema, Jeromy; Betarbet, Ranjita; Walker, Lary C.

    2015-01-01

    The misfolding and aggregation of the Aβ peptide – a fundamental event in the pathogenesis of Alzheimer’s disease – can be instigated in the brains of experimental animals by the intracranial infusion of brain extracts that are rich in aggregated Aβ. Recent experiments have found that the peripheral (intraperitoneal) injection of Aβ seeds induces Aβ deposition in the brains of APP-transgenic mice, largely in the form of cerebral amyloid angiopathy. Macrophage-type cells normally are involved in pathogen neutralization and antigen presentation, but under some circumstances, circulating monocytes have been found to act as vectors for the transport of pathogenic agents such as viruses and prions. The present study assessed the ability of peripheral monocytes to transport Aβ aggregates from the peritoneal cavity to the brain. Our initial experiments showed that intravenously delivered macrophages that had previously ingested fluorescent nanobeads as tracers migrate primarily to peripheral organs such as spleen and liver, but that a small number also reach the brain parenchyma. We next injected CD45.1-expressing monocytes from donor mice intravenously into CD45.2-expressing host mice; after 24 hours, analysis by fluorescence-activated cell sorting (FACS) and histology confirmed that some CD45.1 monocytes enter the brain, particularly in the superficial cortex and around blood vessels. When the donor monocytes are first exposed to Aβ-rich brain extracts from human AD cases, a subset of intravenously delivered Aβ-containing cells migrate to the brain. These experiments indicate that, in mouse models, circulating monocytes are potential vectors by which exogenously delivered, aggregated Aβ travels from periphery to brain, and more generally support the hypothesis that macrophage-type cells can participate in the dissemination of proteopathic seeds. PMID:26168900

  6. The Functional Role of the Periphery in Emotional Language Comprehension

    PubMed Central

    Havas, David A.; Matheson, James

    2013-01-01

    Language can impact emotion, even when it makes no reference to emotion states. For example, reading sentences with positive meanings (“The water park is refreshing on the hot summer day”) induces patterns of facial feedback congruent with the sentence emotionality (smiling), whereas sentences with negative meanings induce a frown. Moreover, blocking facial afference with botox selectively slows comprehension of emotional sentences. Therefore, theories of cognition should account for emotion-language interactions above the level of explicit emotion words, and the role of peripheral feedback in comprehension. For this special issue exploring frontiers in the role of the body and environment in cognition, we propose a theory in which facial feedback provides a context-sensitive constraint on the simulation of actions described in language. Paralleling the role of emotions in real-world behavior, our account proposes that (1) facial expressions accompany sudden shifts in wellbeing as described in language; (2) facial expressions modulate emotional action systems during reading; and (3) emotional action systems prepare the reader for an effective simulation of the ensuing language content. To inform the theory and guide future research, we outline a framework based on internal models for motor control. To support the theory, we assemble evidence from diverse areas of research. Taking a functional view of emotion, we tie the theory to behavioral and neural evidence for a role of facial feedback in cognition. Our theoretical framework provides a detailed account that can guide future research on the role of emotional feedback in language processing, and on interactions of language and emotion. It also highlights the bodily periphery as relevant to theories of embodied cognition. PMID:23750145

  7. The functional role of the periphery in emotional language comprehension.

    PubMed

    Havas, David A; Matheson, James

    2013-01-01

    Language can impact emotion, even when it makes no reference to emotion states. For example, reading sentences with positive meanings ("The water park is refreshing on the hot summer day") induces patterns of facial feedback congruent with the sentence emotionality (smiling), whereas sentences with negative meanings induce a frown. Moreover, blocking facial afference with botox selectively slows comprehension of emotional sentences. Therefore, theories of cognition should account for emotion-language interactions above the level of explicit emotion words, and the role of peripheral feedback in comprehension. For this special issue exploring frontiers in the role of the body and environment in cognition, we propose a theory in which facial feedback provides a context-sensitive constraint on the simulation of actions described in language. Paralleling the role of emotions in real-world behavior, our account proposes that (1) facial expressions accompany sudden shifts in wellbeing as described in language; (2) facial expressions modulate emotional action systems during reading; and (3) emotional action systems prepare the reader for an effective simulation of the ensuing language content. To inform the theory and guide future research, we outline a framework based on internal models for motor control. To support the theory, we assemble evidence from diverse areas of research. Taking a functional view of emotion, we tie the theory to behavioral and neural evidence for a role of facial feedback in cognition. Our theoretical framework provides a detailed account that can guide future research on the role of emotional feedback in language processing, and on interactions of language and emotion. It also highlights the bodily periphery as relevant to theories of embodied cognition.

  8. ACS: ALMA Common Software

    NASA Astrophysics Data System (ADS)

    Chiozzi, Gianluca; Šekoranja, Matej

    2013-02-01

    ALMA Common Software (ACS) provides a software infrastructure common to all ALMA partners and consists of a documented collection of common patterns and components which implement those patterns. The heart of ACS is based on a distributed Component-Container model, with ACS Components implemented as CORBA objects in any of the supported programming languages. ACS provides common CORBA-based services such as logging, error and alarm management, configuration database and lifecycle management. Although designed for ALMA, ACS can and is being used in other control systems and distributed software projects, since it implements proven design patterns using state of the art, reliable technology. It also allows, through the use of well-known standard constructs and components, that other team members whom are not authors of ACS easily understand the architecture of software modules, making maintenance affordable even on a very large project.

  9. A decisional account of subjective inflation of visual perception at the periphery.

    PubMed

    Solovey, Guillermo; Graney, Guy Gerard; Lau, Hakwan

    2015-01-01

    Human peripheral vision appears vivid compared to foveal vision; the subjectively perceived level of detail does not seem to drop abruptly with eccentricity. This compelling impression contrasts with the fact that spatial resolution is substantially lower at the periphery. A similar phenomenon occurs in visual attention, in which subjects usually overestimate their perceptual capacity in the unattended periphery. We have previously shown that at identical eccentricity, low spatial attention is associated with liberal detection biases, which we argue may reflect inflated subjective perceptual qualities. Our computational model suggests that this subjective inflation occurs because under the lack of attention, the trial-by-trial variability of the internal neural response is increased, resulting in more frequent surpassing of a detection criterion. In the current work, we hypothesized that the same mechanism may be at work in peripheral vision. We investigated this possibility in psychophysical experiments in which participants performed a simultaneous detection task at the center and at the periphery. Confirming our hypothesis, we found that participants adopted a conservative criterion at the center and liberal criterion at the periphery. Furthermore, an extension of our model predicts that detection bias will be similar at the center and at the periphery if the periphery stimuli are magnified. A second experiment successfully confirmed this prediction. These results suggest that, although other factors contribute to subjective inflation of visual perception in the periphery, such as top-down filling-in of information, the decision mechanism may be relevant too.

  10. Ultraviolet Light Transmission through the Human Corneal Stroma Is Reduced in the Periphery

    PubMed Central

    Doutch, James J.; Quantock, Andrew J.; Joyce, Nancy C.; Meek, Keith M.

    2012-01-01

    This article investigates in vitro light transmission through the human cornea in the ultraviolet (UV) portion of the electromagnetic spectrum as a function of position across the cornea from center to periphery. Spectrophotometry was used to measure UV transmission in the wavelength range 310–400 nm, from the central cornea to its periphery. UV transmission decreases away from the center, and this is attributed to scattering and absorbance. Corneal endothelial cells, which line the back of the cornea and are more numerous in the periphery, therefore receive a lower dose of UV than do those in the central cornea. This is consistent with the recent observation that endothelial cells in the corneal periphery exhibit less nuclear oxidative DNA damage than those in the central cornea. PMID:22455908

  11. Recruitment to the Nuclear Periphery Can Alter Expression of Genes in Human Cells

    PubMed Central

    Finlan, Lee E.; Sproul, Duncan; Thomson, Inga; Boyle, Shelagh; Kerr, Elizabeth; Perry, Paul; Ylstra, Bauke; Chubb, Jonathan R.; Bickmore, Wendy A.

    2008-01-01

    The spatial organisation of the genome in the nucleus has a role in the regulation of gene expression. In vertebrates, chromosomal regions with low gene-density are located close to the nuclear periphery. Correlations have also been made between the transcriptional state of some genes and their location near the nuclear periphery. However, a crucial issue is whether this level of nuclear organisation directly affects gene function, rather than merely reflecting it. To directly investigate whether proximity to the nuclear periphery can influence gene expression in mammalian cells, here we relocate specific human chromosomes to the nuclear periphery by tethering them to a protein of the inner nuclear membrane. We show that this can reversibly suppress the expression of some endogenous human genes located near the tethering sites, and even genes further away. However, the expression of many other genes is not detectably reduced and we show that location at the nuclear periphery is not incompatible with active transcription. The dampening of gene expression around the nuclear periphery is dependent on the activity of histone deacetylases. Our data show that the radial position within the nucleus can influence the expression of some, but not all, genes. This is compatible with the suggestion that re-localisation of genes relative to the peripheral zone of the nucleus could be used by metazoans to modulate the expression of selected genes during development and differentiation. PMID:18369458

  12. THYRATRON SWITCH

    DOEpatents

    Creveling, R.; Bourgeois, N.A. Jr.

    1959-04-21

    An arrangement for utilizing a thyratron as a noise free switch is described. It has been discovered that the voltage between plate and cathode of a thyratron will oscillate, producing voltage spikes, if the tube carries only a fraction of its maximum rated current. These voltage spikes can produce detrimental effects where the thyratron is used in critical timing circuits. To alleviate this problem the disclosed circuit provides a charged capacitor and a resistor in parallel with the tube and of such value that the maximum current will flow from the capacitor through the thyratron when it is triggered. During this time the signal current is conducted through the tube, before the thyratron voltage starts to oscillate, and the signal current output is free of noise spikes.

  13. Microfabricated AC impedance sensor

    DOEpatents

    Krulevitch, Peter; Ackler, Harold D.; Becker, Frederick; Boser, Bernhard E.; Eldredge, Adam B.; Fuller, Christopher K.; Gascoyne, Peter R. C.; Hamilton, Julie K.; Swierkowski, Stefan P.; Wang, Xiao-Bo

    2002-01-01

    A microfabricated instrument for detecting and identifying cells and other particles based on alternating current (AC) impedance measurements. The microfabricated AC impedance sensor includes two critical elements: 1) a microfluidic chip, preferably of glass substrates, having at least one microchannel therein and with electrodes patterned on both substrates, and 2) electrical circuits that connect to the electrodes on the microfluidic chip and detect signals associated with particles traveling down the microchannels. These circuits enable multiple AC impedance measurements of individual particles at high throughput rates with sufficient resolution to identify different particle and cell types as appropriate for environmental detection and clinical diagnostic applications.

  14. Utilizing zero-sequence switchings for reversible converters

    DOEpatents

    Hsu, John S.; Su, Gui-Jia; Adams, Donald J.; Nagashima, James M.; Stancu, Constantin; Carlson, Douglas S.; Smith, Gregory S.

    2004-12-14

    A method for providing additional dc inputs or outputs (49, 59) from a dc-to-ac inverter (10) for controlling motor loads (60) comprises deriving zero-sequence components (V.sub.ao, V.sub.bo, and V.sub.co) from the inverter (10) through additional circuit branches with power switching devices (23, 44, 46), transforming the voltage between a high voltage and a low voltage using a transformer or motor (42, 50), converting the low voltage between ac and dc using a rectifier (41, 51) or an H-bridge (61), and providing at least one low voltage dc input or output (49, 59). The transformation of the ac voltage may be either single phase or three phase. Where less than a 100% duty cycle is acceptable, a two-phase modulation of the switching signals controlling the inverter (10) reduces switching losses in the inverter (10). A plurality of circuits for carrying out the invention are also disclosed.

  15. Development of a hardware-based AC microgrid for AC stability assessment

    NASA Astrophysics Data System (ADS)

    Swanson, Robert R.

    As more power electronic-based devices enable the development of high-bandwidth AC microgrids, the topic of microgrid power distribution stability has become of increased interest. Recently, researchers have proposed a relatively straightforward method to assess the stability of AC systems based upon the time-constants of sources, the net bus capacitance, and the rate limits of sources. In this research, a focus has been to develop a hardware test system to evaluate AC system stability. As a first step, a time domain model of a two converter microgrid was established in which a three phase inverter acts as a power source and an active rectifier serves as an adjustable constant power AC load. The constant power load can be utilized to create rapid power flow transients to the generating system. As a second step, the inverter and active rectifier were designed using a Smart Power Module IGBT for switching and an embedded microcontroller as a processor for algorithm implementation. The inverter and active rectifier were designed to operate simultaneously using a synchronization signal to ensure each respective local controller operates in a common reference frame. Finally, the physical system was created and initial testing performed to validate the hardware functionality as a variable amplitude and variable frequency AC system.

  16. Isolation of sequences flanking Ac insertion sites by Ac casting.

    PubMed

    Wang, Dafang; Peterson, Thomas

    2013-01-01

    Localizing Ac insertions is a fundamental task in studying Ac-induced mutation and chromosomal rearrangements involving Ac elements. Researchers may sometimes be faced with the situation in which the sequence flanking one side of an Ac/Ds element is known, but the other flank is unknown. Or, a researcher may have a small sequence surrounding the Ac/Ds insertion site and needs to obtain additional flanking genomic sequences. One way to rapidly clone unknown Ac/Ds flanking sequences is via a PCR-based method termed Ac casting. This approach utilizes the somatic transposition activity of Ac during plant development, and provides an efficient means for short-range genome walking. Here we describe the principle of Ac casting, and show how it can be applied to isolate Ac macrotransposon insertion sites.

  17. Switch Transcripts in Immunoglobulin Class Switching

    NASA Astrophysics Data System (ADS)

    Lorenz, Matthias; Jung, Steffen; Radbruch, Andreas

    1995-03-01

    B cells can exchange gene segments for the constant region of the immunoglobulin heavy chain, altering the class and effector function of the antibodies that they produce. Class switching is directed to distinct classes by cytokines, which induce transcription of the targeted DNA sequences. These transcripts are processed, resulting in spliced "switch" transcripts. Switch recombination can be directed to immunoglobulin G1 (IgG1) by the heterologous human metallothionein II_A promoter in mutant mice. Induction of the structurally conserved, spliced switch transcripts is sufficient to target switch recombination to IgG1, whereas transcription alone is not.

  18. Multiple DC, single AC converter with a switched DC transformer

    DOEpatents

    Donnelly, Matthew K.; Hammerstrom, Donald J.

    1997-01-01

    The invention is an improvement of the PASC inverter, wherein the improvements include the reduction from two shorting gates per transformer to one shorting gate per transformer and replacement of active control of the shorting gate with passive control of the shorting gate. Further advantages are obtained through the use of anti-parallel gate sets.

  19. Multiple DC, single AC converter with a switched DC transformer

    DOEpatents

    Donnelly, M.K.; Hammerstrom, D.J.

    1997-05-20

    The invention is an improvement of the PASC inverter, wherein the improvements include the reduction from two shorting gates per transformer to one shorting gate per transformer and replacement of active control of the shorting gate with passive control of the shorting gate. Further advantages are obtained through the use of anti-parallel gate sets. 14 figs.

  20. The nuclear periphery of embryonic stem cells is a transcriptionally permissive and repressive compartment

    PubMed Central

    Luo, Li; Gassman, Katherine L.; Petell, Lydia M.; Wilson, Christian L.; Bewersdorf, Joerg; Shopland, Lindsay S.

    2009-01-01

    Summary Chromatin adapts a distinct structure and epigenetic state in embryonic stem cells (ESCs), but how chromatin is three-dimensionally organized within the ESC nucleus is poorly understood. Because nuclear location can influence gene expression, we examined the nuclear distributions of chromatin with key epigenetic marks in ESC nuclei. We focused on chromatin at the nuclear periphery, a compartment that represses some but not all associated genes and accumulates facultative heterochromatin in differentiated cells. Using a quantitative, cytological approach, we measured the nuclear distributions of genes in undifferentiated mouse ESCs according to epigenetic state and transcriptional activity. We found that trimethyl histone H3 lysine 27 (H3K27-Me3), which marks repressed gene promoters, is enriched at the ESC nuclear periphery. In addition, this compartment contains 10-15% of chromatin with active epigenetic marks and hundreds of transcription sites. Surprisingly, comparisons with differentiated cell types revealed similar nuclear distributions of active chromatin. By contrast, H3K27-Me3 was less concentrated at the nuclear peripheries of differentiated cells. These findings demonstrate that the nuclear periphery is an epigenetically dynamic compartment that might be distinctly marked in pluripotent ESCs. In addition, our data indicate that the nuclear peripheries of multiple cell types can contain a significant fraction of both active and repressed genes. PMID:19773359

  1. Latching relay switch assembly

    DOEpatents

    Duimstra, Frederick A.

    1991-01-01

    A latching relay switch assembly which includes a coil section and a switch or contact section. The coil section includes at least one permanent magnet and at least one electromagnet. The respective sections are, generally, arranged in separate locations or cavities in the assembly. The switch is latched by a permanent magnet assembly and selectively switched by an overriding electromagnetic assembly.

  2. Electronically commutated serial-parallel switching for motor windings

    DOEpatents

    Hsu, John S.

    2012-03-27

    A method and a circuit for controlling an ac machine comprises controlling a full bridge network of commutation switches which are connected between a multiphase voltage source and the phase windings to switch the phase windings between a parallel connection and a series connection while providing commutation discharge paths for electrical current resulting from inductance in the phase windings. This provides extra torque for starting a vehicle from lower battery current.

  3. Anthem simulational studies of the plasma opening switch

    SciTech Connect

    Mason, R.J.

    1992-01-01

    For a deeper understanding of the physical processes governing the Plasma Opening Switch (POS) we use the ANTHEM 2D implicit simulation code to study: (1) ion dynamical effects on electrohydrodynamic (EHD) waves propagating along steep density interfaces in the switch plasmas. At radial interfaces where the density jumps toward the anode, these waves can drive a finger of magnetic field into the plasma toward the load. Ion dynamics can open the rear of such fingers into a wedge-like density gap. Then: (2) we examine ion effects in uniform switch plasmas. These first develop potential hill structures at the drive edge of the cathode from the competition between electron velocity advection and EHD magnetic exclusion waves. Magnetic pressure gradients at the hill periphery and EHD effects then establish a density gap propagating along the cathode with radial electron emission from its tip. Similar results are obtained under both multi-fluid and PIC modeling of the plasma components.

  4. Anthem simulational studies of the plasma opening switch

    SciTech Connect

    Mason, R.J.

    1992-07-01

    For a deeper understanding of the physical processes governing the Plasma Opening Switch (POS) we use the ANTHEM 2D implicit simulation code to study: (1) ion dynamical effects on electrohydrodynamic (EHD) waves propagating along steep density interfaces in the switch plasmas. At radial interfaces where the density jumps toward the anode, these waves can drive a finger of magnetic field into the plasma toward the load. Ion dynamics can open the rear of such fingers into a wedge-like density gap. Then: (2) we examine ion effects in uniform switch plasmas. These first develop potential hill structures at the drive edge of the cathode from the competition between electron velocity advection and EHD magnetic exclusion waves. Magnetic pressure gradients at the hill periphery and EHD effects then establish a density gap propagating along the cathode with radial electron emission from its tip. Similar results are obtained under both multi-fluid and PIC modeling of the plasma components.

  5. Simple eye-hand reaction time in the retinal periphery can be reduced with training.

    PubMed

    Ciuffreda, Kenneth J

    2011-05-01

    One critical aspect of sports vision is eye-hand reaction time, especially for visual stimuli in the retinal periphery. A key question is, "Can eye-hand reaction time be reduced with training?" Evidence from a series of recent experiments suggests that it can. The results in the retinal periphery demonstrated the following: (1) eye-hand reaction time can be reduced by training a small extent (∼10-20 msec) involving central visual processing changes, (2) the training effect transfers to other retinal loci, and (3) the improvement is retained following the cessation of training. These results suggest that training of eye-hand reaction time in the retinal periphery should be considered in athletes to potentially improve their on-field sports performance.

  6. Radiation hard vacuum switch

    DOEpatents

    Boettcher, Gordon E.

    1990-01-01

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction.

  7. Radiation hard vacuum switch

    DOEpatents

    Boettcher, Gordon E.

    1990-03-06

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction.

  8. Glioma Cells in the Tumor Periphery Have a Stem Cell Phenotype.

    PubMed

    Munthe, Sune; Petterson, Stine Asferg; Dahlrot, Rikke Hedegaard; Poulsen, Frantz Rom; Hansen, Steinbjørn; Kristensen, Bjarne Winther

    2016-01-01

    Gliomas are highly infiltrative tumors incurable with surgery. Although surgery removes the bulk tumor, tumor cells in the periphery are left behind resulting in tumor relapses. The aim of the present study was to characterize the phenotype of tumor cells in the periphery focusing on tumor stemness, proliferation and chemo-resistance. This was investigated in situ in patient glioma tissue as well as in orthotopic glioblastoma xenografts. We identified 26 gliomas having the R132 mutation in Isocitrate DeHydrogenase 1 (mIDH1). A double immunofluorescence approach identifying mIDH1 positive tumor cells and a panel of markers was used. The panel comprised of six stem cell-related markers (CD133, Musashi-1, Bmi-1, Sox-2, Nestin and Glut-3), a proliferation marker (Ki-67) as well as a chemo-resistance marker (MGMT). Computer-based automated classifiers were designed to measure the mIDH1 positive nucleus area-fraction of the chosen markers. Moreover, orthotopic glioblastoma xenografts from five different patient-derived spheroid cultures were obtained and the tumor cells identified by human specific immunohistochemical markers. The results showed that tumor cells in the periphery of patient gliomas expressed stem cell markers, however for most markers at a significantly lower level than in the tumor core. The Ki-67 level was slightly reduced in the periphery, whereas the MGMT level was similar. In orthotopic glioblastoma xenografts all markers showed similar levels in the core and periphery. In conclusion tumor cells in the periphery of patient gliomas have a stem cell phenotype, although it is less pronounced than in the tumor core. Novel therapies aiming at preventing recurrence should therefore take tumor stemness into account. Migrating cells in orthotopic glioblastoma xenografts preserve expression and stem cell markers. The orthotopic model therefore has a promising translational potential. PMID:27171431

  9. Glioma Cells in the Tumor Periphery Have a Stem Cell Phenotype

    PubMed Central

    Munthe, Sune; Petterson, Stine Asferg; Dahlrot, Rikke Hedegaard; Poulsen, Frantz Rom; Hansen, Steinbjørn; Kristensen, Bjarne Winther

    2016-01-01

    Gliomas are highly infiltrative tumors incurable with surgery. Although surgery removes the bulk tumor, tumor cells in the periphery are left behind resulting in tumor relapses. The aim of the present study was to characterize the phenotype of tumor cells in the periphery focusing on tumor stemness, proliferation and chemo-resistance. This was investigated in situ in patient glioma tissue as well as in orthotopic glioblastoma xenografts. We identified 26 gliomas having the R132 mutation in Isocitrate DeHydrogenase 1 (mIDH1). A double immunofluorescence approach identifying mIDH1 positive tumor cells and a panel of markers was used. The panel comprised of six stem cell-related markers (CD133, Musashi-1, Bmi-1, Sox-2, Nestin and Glut-3), a proliferation marker (Ki-67) as well as a chemo-resistance marker (MGMT). Computer-based automated classifiers were designed to measure the mIDH1 positive nucleus area-fraction of the chosen markers. Moreover, orthotopic glioblastoma xenografts from five different patient-derived spheroid cultures were obtained and the tumor cells identified by human specific immunohistochemical markers. The results showed that tumor cells in the periphery of patient gliomas expressed stem cell markers, however for most markers at a significantly lower level than in the tumor core. The Ki-67 level was slightly reduced in the periphery, whereas the MGMT level was similar. In orthotopic glioblastoma xenografts all markers showed similar levels in the core and periphery. In conclusion tumor cells in the periphery of patient gliomas have a stem cell phenotype, although it is less pronounced than in the tumor core. Novel therapies aiming at preventing recurrence should therefore take tumor stemness into account. Migrating cells in orthotopic glioblastoma xenografts preserve expression and stem cell markers. The orthotopic model therefore has a promising translational potential. PMID:27171431

  10. Three phase AC motor controller

    DOEpatents

    Vuckovich, Michael; Wright, Maynard K.; Burkett, John P.

    1984-03-20

    A motor controller for a three phase AC motor (10) which is adapted to operate bidirectionally from signals received either from a computer (30) or a manual control (32). The controller is comprised of digital logic circuit means which implement a forward and reverse command signal channel (27, 29) for the application of power through the forward and reverse power switching relays (16, 18, 20, 22). The digital logic elements are cross coupled to prevent activation of both channels simultaneously and each includes a plugging circuit (65, 67) for stopping the motor upon the removal of control signal applied to one of the two channels (27, 29) for a direction of rotation desired. Each plugging circuit (65, 67) includes a one-shot pulse signal generator (88, 102) which outputs a single pulse signal of predetermined pulsewidth which is adapted to inhibit further operation of the application of power in the channel which is being activated and to apply a reversal command signal to the other channel which provides a reversed phase application of power to the motor for a period defined by the pulse-width output of the one-shot signal generator to plug the motor (10) which will then be inoperative until another rotational command signal is applied to either of the two channels.

  11. Isolated and soft-switched power converter

    DOEpatents

    Peng, Fang Zheng; Adams, Donald Joe

    2002-01-01

    An isolated and soft-switched power converter is used for DC/DC and DC/DC/AC power conversion. The power converter includes two resonant tank circuits coupled back-to-back through an isolation transformer. Each resonant tank circuit includes a pair of resonant capacitors connected in series as a resonant leg, a pair of tank capacitors connected in series as a tank leg, and a pair of switching devices with anti-parallel clamping diodes coupled in series as resonant switches and clamping devices for the resonant leg. The power converter is well suited for DC/DC and DC/DC/AC power conversion applications in which high-voltage isolation, DC to DC voltage boost, bidirectional power flow, and a minimal number of conventional switching components are important design objectives. For example, the power converter is especially well suited to electric vehicle applications and load-side electric generation and storage systems, and other applications in which these objectives are important. The power converter may be used for many different applications, including electric vehicles, hybrid combustion/electric vehicles, fuel-cell powered vehicles with low-voltage starting, remote power sources utilizing low-voltage DC power sources, such as photovoltaics and others, electric power backup systems, and load-side electric storage and generation systems.

  12. Tevatron AC dipole system

    SciTech Connect

    Miyamoto, R.; Kopp, S.E.; Jansson, A.; Syphers, M.J.; /Fermilab

    2007-06-01

    The AC dipole is an oscillating dipole magnet which can induce large amplitude oscillations without the emittance growth and decoherence. These properties make it a good tool to measure optics of a hadron synchrotron. The vertical AC dipole for the Tevatron is powered by an inexpensive high power audio amplifier since its operating frequency is approximately 20 kHz. The magnet is incorporated into a parallel resonant system to maximize the current. The use of a vertical pinger magnet which has been installed in the Tevatron made the cost relatively inexpensive. Recently, the initial system was upgraded with a more powerful amplifier and oscillation amplitudes up to 2-3{sigma} were achieved with the 980 GeV proton beam. This paper discusses details of the Tevatron AC dipole system and also shows its test results.

  13. AC-3 audio coder

    NASA Astrophysics Data System (ADS)

    Todd, Craig

    1995-12-01

    AC-3 is a system for coding up to 5.1 channels of audio into a low bit-rate data stream. High quality may be obtained with compression ratios approaching 12-1 for multichannel audio programs. The high compression ratio is achieved by methods which do not increase decoder memory, and thus cost. The methods employed include: the transmission of a high frequency resolution spectral envelope; and a novel forward/backward adaptive bit allocation algorithm. In order to satisfy practical requirements of an emissions coder, the AC-3 syntax includes a number of features useful to broadcasters and consumers. These features include: loudness uniformity between programs; dynamic range control; and broadcaster control of downmix coefficients. The AC-3 coder has been formally selected for inclusion of the U.S. HDTV broadcast standard, and has been informally selected for several additional applications.

  14. Temporal switching jitter in photoconductive switches

    SciTech Connect

    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

    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.

  15. System and method for monitoring and controlling stator winding temperature in a de-energized AC motor

    DOEpatents

    Lu, Bin; Luebke, Charles John; Habetler, Thomas G.; Zhang, Pinjia; Becker, Scott K.

    2011-12-27

    A system and method for measuring and controlling stator winding temperature in an AC motor while idling is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of a multi-phase AC motor. The circuit further includes a plurality of switching devices to control current flow and terminal voltages in the multi-phase AC motor and a controller connected to the circuit. The controller is configured to activate the plurality of switching devices to create a DC signal in an output of the motor control device corresponding to an input to the multi-phase AC motor, determine or estimate a stator winding resistance of the multi-phase AC motor based on the DC signal, and estimate a stator temperature from the stator winding resistance. Temperature can then be controlled and regulated by DC injection into the stator windings.

  16. Fast high-temperature superconductor switch for high current applications

    NASA Astrophysics Data System (ADS)

    Solovyov, Vyacheslav F.; Li, Qiang

    2013-07-01

    Reversible operation of a high current superconductor switch based on the quench of high-resistance second generation high temperature superconducting wire is demonstrated. The quench is induced by a burst of an ac field generated by an inductively coupled radio-frequency coil. The switch makes a superconducting-to-normal transition within 5 ms and also has a rapid recovery to the superconducting state. The device has potential applications as an active current limiter or as a storage switch for superconducting magnetic energy storage systems. Operation in a full flux penetration/flow regime can effectively minimize the detrimental effects of the intrinsic conductor non-uniformity.

  17. Latching micro optical switch

    DOEpatents

    Garcia, Ernest J; Polosky, Marc A

    2013-05-21

    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.

  18. AC/RF Superconductivity

    SciTech Connect

    Ciovati, Gianluigi

    2015-02-01

    This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.

  19. On the influence of the heliomagnetospheric periphery on the galactic cosmic rays

    NASA Technical Reports Server (NTRS)

    Krainev, M. B.; Stozhkov, Y. I.; Charakhchyan, T. N.

    1985-01-01

    The suggestion is substantiated that the periphery of the heliomagnetosphere, the region in which properties depend on both solar wind and interstellar space parameters, plays a much more important role in the solar modulation of galactic cosmic rays than previously believed.

  20. Bit by Bit: Innovating at the Periphery to Extend Harvard's Core

    ERIC Educational Resources Information Center

    Laserna, Catalina; Leitner, Henry

    2008-01-01

    Faculty instructional time is a critical resource at all universities, but particularly in a major research institution like Harvard. Operating on the periphery of the Faculty of Arts and Sciences, Harvard's division of Continuing Education is often at a disadvantage when attempting to recruit senior faculty. However, through its distance…

  1. Young Women in a Male Periphery: Experiences from the Scandinavian North.

    ERIC Educational Resources Information Center

    Dahlstrom, Margareta

    1996-01-01

    Suggests that young women migrate from rural to urban areas in northern Scandinavia because the rural "periphery" is dominated by male economic and leisure activities. A study in northern Norway indicates that more young women than young men valued higher education and highly qualified careers, both of which were more attainable in urban than in…

  2. Task-Based Core-Periphery Organization of Human Brain Dynamics

    PubMed Central

    Bassett, Danielle S.; Wymbs, Nicholas F.; Rombach, M. Puck; Porter, Mason A.; Mucha, Peter J.; Grafton, Scott T.

    2013-01-01

    As a person learns a new skill, distinct synapses, brain regions, and circuits are engaged and change over time. In this paper, we develop methods to examine patterns of correlated activity across a large set of brain regions. Our goal is to identify properties that enable robust learning of a motor skill. We measure brain activity during motor sequencing and characterize network properties based on coherent activity between brain regions. Using recently developed algorithms to detect time-evolving communities, we find that the complex reconfiguration patterns of the brain's putative functional modules that control learning can be described parsimoniously by the combined presence of a relatively stiff temporal core that is composed primarily of sensorimotor and visual regions whose connectivity changes little in time and a flexible temporal periphery that is composed primarily of multimodal association regions whose connectivity changes frequently. The separation between temporal core and periphery changes over the course of training and, importantly, is a good predictor of individual differences in learning success. The core of dynamically stiff regions exhibits dense connectivity, which is consistent with notions of core-periphery organization established previously in social networks. Our results demonstrate that core-periphery organization provides an insightful way to understand how putative functional modules are linked. This, in turn, enables the prediction of fundamental human capacities, including the production of complex goal-directed behavior. PMID:24086116

  3. The nucleolus in Entamoeba histolytica and Entamoeba invadens is located at the nuclear periphery.

    PubMed

    Jhingan, Gagan Deep; Panigrahi, Sunil K; Bhattacharya, Alok; Bhattacharya, Sudha

    2009-09-01

    The ribosomal RNA genes in the human parasite Entamoeba histolytica and its reptilian counterpart Entamoeba invadens are located on extrachromosomal circles. The expression of rRNA genes generally takes place in a specialized nuclear compartment-the nucleolus. In Entamoeba species the nuclear space that may be called the nucleolus has yet to be defined. Previous studies showed that the rDNA circles are located at the nuclear periphery. Here we have raised antibodies against the E. histolytica homologue of fibrillarin, a highly conserved protein known to be a marker for nucleolus. These antibodies cross-reacted preferentially with the nuclear periphery, forming a peripheral ring. There was complete colocalization of fibrillarin with the signal obtained by antibodies against E. histolytica RNA polymerase I (but not polymerase II and III), strongly suggesting that the nucleolus in E. histolytica is indeed located at the nuclear periphery. The dynamic nature of the nucleolus was evident when cells were subjected to a variety of growth stresses. Although the peripheral nucleolar structure was retained, stress was accompanied by significant cytoplasmic localization of RNA polymerase I, and to some extent fibrillarin. The nucleolus in E. invadens was also located at the nuclear periphery. When these cells were induced to encyst the nucleolar ring structure was lost, giving way to small, fragmented foci. This study gives the first clear insight into nucleolar structure in Entamoeba.

  4. The Expanded Developmental Periphery: Framing the Institutional Role of University Continuing Education Units

    ERIC Educational Resources Information Center

    Fleming, Josephine

    2013-01-01

    This article argues that Burton Clark's notion of the expanded developmental periphery provides a useful conceptual framework for examining the differing relationships between continuing and professional education units and the institutional core of traditional research universities. The intent is to examine how Clark's notion offers a…

  5. What's the Place of Queer Theory in Studies of Gender, Sexuality, and Education on the Periphery?

    ERIC Educational Resources Information Center

    Rasmussen, Mary Lou

    2016-01-01

    This article is an exploration of the problem of theorizing gender and sexuality of people who Raewyn Connell might describe as coming from the global periphery, but whose lives and futures are also enmeshed in the politics, policies, and pedagogies of the metropole. Elizabeth Povinelli has done extensive research on Indigenous people in the…

  6. Heat Switches for ADRs

    NASA Technical Reports Server (NTRS)

    DiPirro, M. J.; Shirron, P. J.

    2014-01-01

    Heat switches are key elements in the cyclic operation of Adiabatic Demagnetization Refrigerators (ADRs). Several of the types of heat switches that have been used for ADRs are described in this paper. Key elements in selection and design of these switches include not only ON/OFF switching ratio, but also method of actuation, size, weight, and structural soundness. Some of the trade-off are detailed in this paper.

  7. Triggered plasma opening switch

    DOEpatents

    Mendel, Clifford W.

    1988-01-01

    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.

  8. Apollo Ring Optical Switch

    SciTech Connect

    Maestas, J.H.

    1987-03-01

    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.

  9. Triggered plasma opening switch

    SciTech Connect

    Mendel, C W

    1988-02-23

    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.

  10. Electromechanical systems with transient high power response operating from a resonant ac link

    NASA Technical Reports Server (NTRS)

    Burrows, Linda M.; Hansen, Irving G.

    1992-01-01

    The combination of an inherently robust asynchronous (induction) electrical machine with the rapid control of energy provided by a high frequency resonant ac link enables the efficient management of higher power levels with greater versatility. This could have a variety of applications from launch vehicles to all-electric automobiles. These types of systems utilize a machine which is operated by independent control of both the voltage and frequency. This is made possible by using an indirect field-oriented control method which allows instantaneous torque control all four operating quadrants. Incorporating the ac link allows the converter in these systems to switch at the zero crossing of every half cycle of the ac waveform. This zero loss switching of the link allows rapid energy variations to be achieved without the usual frequency proportional switching loss. Several field-oriented control systems were developed under contract to NASA.

  11. AC power systems handbook

    SciTech Connect

    Whitaker, J.

    1991-01-01

    Transient disturbances are what headaches are made of. Whatever you call them-spikes, surges, are power bumps-they can take your equipment down and leave you with a complicated and expensive repair job. Protection against transient disturbances is a science that demands attention to detail. This book explains how the power distribution system works, what can go wrong with it, and how to protect a facility against abnormalities. system grounding and shielding are covered in detail. Each major method of transient protection is analyzed and its relative merits discussed. The book provides a complete look at the critical elements of the ac power system. Provides a complete look at the ac power system from generation to consumption. Discusses the mechanisms that produce transient disturbances and how to protect against them. Presents diagrams to facilitate system design. Covers new areas, such as the extent of the transient disturbance problem, transient protection options, and stand-by power systems.

  12. Three-phase ac-to-ac series-resonant power converter with a reduced number of thyristors

    SciTech Connect

    Klaassens, J.B.; de Beer, F. )

    1991-07-01

    This paper reports that ac-ac series-resonant converters have been proven to be functional and useful. Power pulse modulation with internal frequencies of tens of kHz and suited for multikilowatt power levels is applied to a series-resonant converter system for generating synthesized multiphase bipolar waveforms with reversible power flow and flow distortion. The use of a series-resonant circuit for power transfer and control obtains natural current commutation of the thyristors and the prevention of excessive stresses on components. Switches are required which have bidirectional current conduction and voltage blocking ability. The conventional series-resonant ac-ac converter applies a total for 24 anti-parallel thyristors. An alternative circuit configuration for the series-resonant ac-ac converter with only 12 thyristors is also presented. The alternative power circuit has three neutrals, related to the polyphase source, the load and the converter, which may be interconnected. If they are connected, the high-frequency component of the source and load currents will flow through the connection between the neutrals. The test results of a converter system generating three-phase sinusoidal input and output waveforms have demonstrated the significant aspects of this type of power interfaces.

  13. Increased Ac excision (iae): Arabidopsis thaliana mutations affecting Ac transposition.

    PubMed

    Jarvis, P; Belzile, F; Page, T; Dean, C

    1997-05-01

    The maize transposable element Ac is highly active in the heterologous hosts tobacco and tomato, but shows very much reduced levels of activity in Arabidopsis. A mutagenesis experiment was undertaken with the aim of identifying Arabidopsis host factors responsible for the observed low levels of Ac activity. Seed from a line carrying a single copy of the Ac element inserted into the streptomycin phosphotransferase (SPT) reporter fusion, and which displayed typically low levels of Ac activity, were mutagenized using gamma rays. Nineteen mutants displaying high levels of somatic Ac activity, as judged by their highly variegated phenotypes, were isolated after screening the M2 generation on streptomycin-containing medium. The mutations fall into two complementation groups, iae1 and iae2, are unlinked to the SPT::Ac locus and segregate in a Mendelian fashion. The iae1 mutation is recessive and the iae2 mutation is semi-dominant. The iae1 and iae2 mutants show 550- and 70-fold increases, respectively, in the average number of Ac excision sectors per cotyledon. The IAE1 locus maps to chromosome 2, whereas the SPT::Ac reporter maps to chromosome 3. A molecular study of Ac activity in the iae1 mutant confirmed the very high levels of Ac excision predicted using the phenotypic assay, but revealed only low levels of Ac re-insertion. Analyses of germinal transposition in the iae1 mutant demonstrated an average germinal excision frequency of 3% and a frequency of independent Ac re-insertions following germinal excision of 22%. The iae mutants represents a possible means of improving the efficiency of Ac/Ds transposon tagging systems in Arabidopsis, and will enable the dissection of host involvement in Ac transposition and the mechanisms employed for controlling transposable element activity.

  14. REMOTE CONTROLLED SWITCHING DEVICE

    DOEpatents

    Hobbs, J.C.

    1959-02-01

    An electrical switching device which can be remotely controlled and in which one or more switches may be accurately operated at predetermined times or with predetermined intervening time intervals is described. The switching device consists essentially of a deck, a post projecting from the deck at right angles thereto, cam means mounted for rotation around said posts and a switch connected to said deck and actuated by said cam means. Means is provided for rotating the cam means at a constant speed and the switching apparatus is enclosed in a sealed container with external adjusting means and electrical connection elements.

  15. Structure of the spatial periphery of the isotopes {sup 9,11}Li

    SciTech Connect

    Galanina, L. I. Zelenskaya, N. S.

    2015-07-15

    The cross sections for the (t, p) reactions on the lithium isotopes {sup 9,11}Li were calculated within a theoretical approach based on employing integral equations of the four-body problem in the Alt—Grassberger-Sandhas formalism and the multiparticle shell model. This made it possible to determine the wave functions for the relative motion of various clusters and the nuclear core and to calculate, on their basis, the root-mean-square radii of nuclei of the isotopes {sup 9,11}Li and the spatial structure of their neutron periphery. It is shown that the {sup 9}Li nucleus has virtually no neutron halo. The {sup 11}Li nucleus is a Borromean halo nucleus. The two-neutron periphery of this nucleus manifests itself in both spatial configurations, a dineutron and a cigar one, the respective root-mean-square radii being large (about 6.5 to 6.9 fm)

  16. Synthesis of Periphery-Decorated and Core-Initiated Borane Polyanionic Macromolecules.

    PubMed

    Teixidor, Francesc; Pepiol, Ariadna; Viñas, Clara

    2015-07-20

    A new class of globular polybranched macromolecules that contain multiple anionic metallacarborane clusters at the o-carborane periphery is reported. The water soluble high boron rich containing molecules could be of interest for boron neutron capture therapy (BNCT) as well as for drug delivery. The reinforced electrostatic noncovalent interactions between anionic polyethylene glycol cobaltabisdicarbollide (PEG-COSAN) branches and the ammonium cation have been shown using ESI-MS.

  17. Inhibition of acute inflammation in the periphery by central action of salicylates.

    PubMed Central

    Catania, A; Arnold, J; Macaluso, A; Hiltz, M E; Lipton, J M

    1991-01-01

    Understanding of the antiinflammatory actions of nonsteroidal drugs is incomplete, but these actions are believed to occur in the periphery, without any contribution from the central nervous system. Recent research on the antipyretic antiinflammatory neuropeptide alpha-melanocyte-stimulating hormone indicates that it can act centrally to inhibit peripheral inflammation; this raises the possibility that other agents, such as nonsteroidal antiinflammatory drugs, may have similar activity. In the present research both lysine acetylsalicylate and sodium salicylate inhibited edema, induced in the mouse ear by topical application of picryl chloride, when injected into the lateral cerebral ventricle. This inhibitory activity on a measure of acute inflammation was not due to escape of the drugs into the periphery, because systemic injection of doses that were effective centrally did not affect inflammation. In contrast, central administration of a dose of indomethacin that was antiinflammatory when given intraperitoneally did not inhibit peripheral inflammation. Thus indomethacin apparently lacks the central antiinflammatory action of the salicylates. This observation, plus our inability to demonstrate either an antiinflammatory effect of intracerebroventricular dexamethasone, a prostaglandin inhibitor, or a pro-inflammatory influence of prostaglandin E2, suggests that prostaglandins are not important to central modulation of inflammation. The results indicate that, in addition to having central influences on fever and pain, salicylates can act within the brain to inhibit acute inflammation in the periphery. Images PMID:1924313

  18. Revealing a comet-like shape of the faint periphery of the nearby galaxy M 32

    NASA Astrophysics Data System (ADS)

    Georgiev, Ts. B.

    2016-02-01

    We performed BVRI photometry of the galaxy M 32 building images and isophote maps in magnitudes and in color indexes. While searching for the faint thick disk of M 32 we apply median filtering with aperture of 7.3 arcmin to detach the residual image of M 32 and its periphery above the surrounding magnitude or color background. The residual images in all photometric systems show that the periphery of M 32 possesses a comet-like shape with a tail oriented to SSE, in a direction opposite to the direction of M 110. The images calibrated in color indexes (b - v) and (b - v)+(r - i) show that the tail is redder than the local median background. The residual images in color indexes show that the red tail broadens and curves in direction towards S and SW. Simultaneously, the brightest part of M 32 occurs bounded from NW-NE-SE sides by a sickle-like formation with a significantly lower red color index. Generally, we do not find a faint thick disk of M 32. However, the comet-like shape on the periphery of M 32, especially as a formation with an increased red color index, provokes involuntarily the impression that the satellite M 32 overtakes the Andromeda galaxy. The redshifts show that the intimacy velocity of M 32 and Andromeda galaxy is about 100 km/s.

  19. Reducing crowding by weakening inhibitory lateral interactions in the periphery with perceptual learning.

    PubMed

    Maniglia, Marcello; Pavan, Andrea; Cuturi, Luigi F; Campana, Gianluca; Sato, Giovanni; Casco, Clara

    2011-01-01

    We investigated whether lateral masking in the near-periphery, due to inhibitory lateral interactions at an early level of central visual processing, could be weakened by perceptual learning and whether learning transferred to an untrained, higher-level lateral masking known as crowding. The trained task was contrast detection of a Gabor target presented in the near periphery (4°) in the presence of co-oriented and co-aligned high contrast Gabor flankers, which featured different target-to-flankers separations along the vertical axis that varied from 2λ to 8λ. We found both suppressive and facilitatory lateral interactions at target-to-flankers distances (2λ - 4λ and 8λ, respectively) that were larger than those found in the fovea. Training reduces suppression but does not increase facilitation. Most importantly, we found that learning reduces crowding and improves contrast sensitivity, but has no effect on visual acuity (VA). These results suggest a different pattern of connectivity in the periphery with respect to the fovea as well as a different modulation of this connectivity via perceptual learning that not only reduces low-level lateral masking but also reduces crowding. These results have important implications for the rehabilitation of low-vision patients who must use peripheral vision to perform tasks, such as reading and refined figure-ground segmentation, which normal sighted subjects perform in the fovea.

  20. Optoelectronic techniques for broadband switching

    NASA Astrophysics Data System (ADS)

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

    1988-01-01

    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.

  1. Modelling, analyses and design of switching converters

    NASA Technical Reports Server (NTRS)

    Cuk, S. M.; Middlebrook, R. D.

    1978-01-01

    A state-space averaging method for modelling switching dc-to-dc converters for both continuous and discontinuous conduction mode is developed. In each case the starting point is the unified state-space representation, and the end result is a complete linear circuit model, for each conduction mode, which correctly represents all essential features, namely, the input, output, and transfer properties (static dc as well as dynamic ac small-signal). While the method is generally applicable to any switching converter, it is extensively illustrated for the three common power stages (buck, boost, and buck-boost). The results for these converters are then easily tabulated owing to the fixed equivalent circuit topology of their canonical circuit model. The insights that emerge from the general state-space modelling approach lead to the design of new converter topologies through the study of generic properties of the cascade connection of basic buck and boost converters.

  2. AC resistance measuring instrument

    DOEpatents

    Hof, P.J.

    1983-10-04

    An auto-ranging AC resistance measuring instrument for remote measurement of the resistance of an electrical device or circuit connected to the instrument includes a signal generator which generates an AC excitation signal for application to a load, including the device and the transmission line, a monitoring circuit which provides a digitally encoded signal representing the voltage across the load, and a microprocessor which operates under program control to provide an auto-ranging function by which range resistance is connected in circuit with the load to limit the load voltage to an acceptable range for the instrument, and an auto-compensating function by which compensating capacitance is connected in shunt with the range resistance to compensate for the effects of line capacitance. After the auto-ranging and auto-compensation functions are complete, the microprocessor calculates the resistance of the load from the selected range resistance, the excitation signal, and the load voltage signal, and displays of the measured resistance on a digital display of the instrument. 8 figs.

  3. AC Resistance measuring instrument

    DOEpatents

    Hof, Peter J.

    1983-01-01

    An auto-ranging AC resistance measuring instrument for remote measurement of the resistance of an electrical device or circuit connected to the instrument includes a signal generator which generates an AC excitation signal for application to a load, including the device and the transmission line, a monitoring circuit which provides a digitally encoded signal representing the voltage across the load, and a microprocessor which operates under program control to provide an auto-ranging function by which range resistance is connected in circuit with the load to limit the load voltage to an acceptable range for the instrument, and an auto-compensating function by which compensating capacitance is connected in shunt with the range resistance to compensate for the effects of line capacitance. After the auto-ranging and auto-compensation functions are complete, the microprocessor calculates the resistance of the load from the selected range resistance, the excitation signal, and the load voltage signal, and displays of the measured resistance on a digital display of the instrument.

  4. Thermally actuated thermionic switch

    DOEpatents

    Barrus, D.M.; Shires, C.D.

    1982-09-30

    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.

  5. Thermally actuated thermionic switch

    DOEpatents

    Barrus, Donald M.; Shires, Charles D.

    1988-01-01

    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.

  6. Solid state switch

    DOEpatents

    Merritt, Bernard T.; Dreifuerst, Gary R.

    1994-01-01

    A solid state switch, with reverse conducting thyristors, is designed to operate at 20 kV hold-off voltage, 1500 A peak, 1.0 .mu.s pulsewidth, and 4500 pps, to replace thyratrons. The solid state switch is more reliable, more economical, and more easily repaired. The switch includes a stack of circuit card assemblies, a magnetic assist and a trigger chassis. Each circuit card assembly contains a reverse conducting thyristor, a resistor capacitor network, and triggering circuitry.

  7. Reusable fast opening switch

    DOEpatents

    Van Devender, John P.; Emin, David

    1986-01-01

    A reusable fast opening switch for transferring energy, in the form of a high power pulse, from an electromagnetic storage device such as an inductor into a load. The switch is efficient, compact, fast and reusable. The switch comprises a ferromagnetic semiconductor which undergoes a fast transition between conductive and insulating states at a critical temperature and which undergoes the transition without a phase change in its crystal structure. A semiconductor such as europium rich europhous oxide, which undergoes a conductor to insulator transition when it is joule heated from its conductor state, can be used to form the switch.

  8. Reusable fast opening switch

    DOEpatents

    Van Devender, J.P.; Emin, D.

    1983-12-21

    A reusable fast opening switch for transferring energy, in the form of a high power pulse, from an electromagnetic storage device such as an inductor into a load. The switch is efficient, compact, fast and reusable. The switch comprises a ferromagnetic semiconductor which undergoes a fast transition between conductive and metallic states at a critical temperature and which undergoes the transition without a phase change in its crystal structure. A semiconductor such as europium rich europhous oxide, which undergoes a conductor to insulator transition when it is joule heated from its conductor state, can be used to form the switch.

  9. Alarm toe switch

    DOEpatents

    Ganyard, Floyd P.

    1982-01-01

    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.

  10. Identification of /sup 233/Ac

    SciTech Connect

    Chu, Y.Y.; Zhou, M.L.

    1983-09-01

    We report in this paper identification of the new isotope /sup 233/Ac. Uranium targets were irradiated with 28 GeV protons; after rapid retrieval of the target and separation of actinium from thorium, /sup 233/Ac was allowed to decay into the known /sup 233/Th daughter. Exhaustive chemical purification was employed to permit the identification of /sup 233/Th via its characteristic ..gamma.. radiations. The half-life derived for /sup 233/Ac from several experiments is 2.3 +- 0.3 min. The production cross section for /sup 233/Ac is 100 ..mu..b.

  11. AC and DC power transmission

    SciTech Connect

    Not Available

    1985-01-01

    The technical and economic assessment of AC and DC transmission systems; long distance transmission, cable transmission, system inter-connection, voltage support, reactive compensation, stabilisation of systems; parallel operation of DC links with AC systems; comparison between alternatives for particular schemes. Design and application equipment: design, testing and application of equipment for HVDC, series and shunt static compensated AC schemes, including associated controls. Installations: overall design of stations and conductor arrangements for HVDC, series and shunt static AC schemes including insulation co-ordination. System analysis and modelling.

  12. Biodegradable resistive switching memory based on magnesium difluoride.

    PubMed

    Zhang, Zhiping; Tsang, Melissa; Chen, I-Wei

    2016-08-11

    This study presents a new type of resistive switching memory device that can be used in biodegradable electronic applications. The biodegradable device features magnesium difluoride as the active layer and iron and magnesium as the corresponding electrodes. This is the first report on magnesium difluoride as a resistive switching layer. With on-off ratios larger than one hundred, the device on silicon switches at voltages less than one volt and requires only sub-mA programming current. AC endurance of 10(3) cycles is demonstrated with ±1 V voltage pulses. The switching mechanism is attributed to the formation and rupture of conductive filaments comprising fluoride vacancies in magnesium difluoride. Devices fabricated on a flexible polyethylene terephthalate substrate are tested for functionality, and degradation is subsequently demonstrated in de-ionized water. An additional layer of magnesium difluoride is used to hinder the degradation and extend the lifetime of the device. PMID:27476796

  13. Single-switch 3{phi} PWM low harmonic rectifiers

    SciTech Connect

    Ismail, E.H.; Erickson, R.

    1996-03-01

    Existing 3{phi} ac-dc low-harmonic rectifiers are costly and require complex control schemes to minimize input current harmonics. Introduced here are two new classes of low cost 3{phi} ac-dc high power factor/low harmonic controlled rectifiers. These are derived from parent dc-dc converter topologies containing boost-type inputs and buck-type inputs. With a single active switch in addition to the diode bridge rectifier, the converters are capable of drawing a high-quality input current waveform naturally at nearly unit power factor. Thus, a simple 3{phi} ac-dc high power factor rectifier is obtained. Two algorithms are introduced in this paper for constructing a 3{phi} ac-dc high-quality rectifier. These algorithms depend on the simple switched-mode boost-type input converter and buck-type input converter modified by an input filter. For most known dc-dc converters which belong to these classes, there are corresponding 3{phi} ac-dc high power factor topologies, which use the same number of transistors and use six additional fast diodes. Analytical and simulation results are supplied to demonstrate the validity of the concept.

  14. Asymmetrical Switch Costs in Children

    ERIC Educational Resources Information Center

    Ellefson, Michelle R.; Shapiron, Laura R.; Chater, Nick

    2006-01-01

    Switching between tasks produces decreases in performance as compared to repeating the same task. Asymmetrical switch costs occur when switching between two tasks of unequal difficulty. This asymmetry occurs because the cost is greater when switching to the less difficult task than when switching to the more difficult task. Various theories about…

  15. Efficient Switches for Solar Power Conversion: Four Quadrant GaN Switch Enabled Three Phase Grid-Tied Microinverters

    SciTech Connect

    2012-02-13

    Solar ADEPT Project: Transphorm is developing power switches for new types of inverters that improve the efficiency and reliability of converting energy from solar panels into useable electricity for the grid. Transistors act as fast switches and control the electrical energy that flows in an electrical circuit. Turning a transistor off opens the circuit and stops the flow of electrical current; turning it on closes the circuit and allows electrical current to flow. In this way a transistor can be used to convert DC from a solar panel into AC for use in a home. Transphorm’s transistors will enable a single semiconductor device to switch electrical currents at high-voltage in both directions—making the inverter more compact and reliable. Transphorm is using Gallium Nitride (GaN) as a semiconductor material in its transistors instead of silicon, which is used in most conventional transistors, because GaN transistors have lower losses at higher voltages and switching frequencies.

  16. Submicrosecond Power-Switching Test Circuit

    NASA Technical Reports Server (NTRS)

    Folk, Eric N.

    2006-01-01

    repetitive waveform from a signal generator, momentary closure of a push-button switch, or closure or opening of a manually operated on/off switch. In the case of a signal generator, one can adjust the frequency and duty cycle as needed to obtain the desired AC power-supply response, which one could display on an oscilloscope. Momentary switch closure could be useful for obtaining (and, if desired, displaying on an oscilloscope set to trigger on an event) the response of a power supply to a single load transient. The on/off switch can be used to switch between load states in which static-load regulation measurements are performed.

  17. Digital ac monitor

    DOEpatents

    Hart, G.W.; Kern, E.C. Jr.

    1987-06-09

    An apparatus and method is provided for monitoring a plurality of analog ac circuits by sampling the voltage and current waveform in each circuit at predetermined intervals, converting the analog current and voltage samples to digital format, storing the digitized current and voltage samples and using the stored digitized current and voltage samples to calculate a variety of electrical parameters; some of which are derived from the stored samples. The non-derived quantities are repeatedly calculated and stored over many separate cycles then averaged. The derived quantities are then calculated at the end of an averaging period. This produces a more accurate reading, especially when averaging over a period in which the power varies over a wide dynamic range. Frequency is measured by timing three cycles of the voltage waveform using the upward zero crossover point as a starting point for a digital timer. 24 figs.

  18. Digital ac monitor

    DOEpatents

    Hart, George W.; Kern, Jr., Edward C.

    1987-06-09

    An apparatus and method is provided for monitoring a plurality of analog ac circuits by sampling the voltage and current waveform in each circuit at predetermined intervals, converting the analog current and voltage samples to digital format, storing the digitized current and voltage samples and using the stored digitized current and voltage samples to calculate a variety of electrical parameters; some of which are derived from the stored samples. The non-derived quantities are repeatedly calculated and stored over many separate cycles then averaged. The derived quantities are then calculated at the end of an averaging period. This produces a more accurate reading, especially when averaging over a period in which the power varies over a wide dynamic range. Frequency is measured by timing three cycles of the voltage waveform using the upward zero crossover point as a starting point for a digital timer.

  19. Cooling Floor AC Systems

    NASA Astrophysics Data System (ADS)

    Jun, Lu; Hao, Ding; Hong, Zhang; Ce, Gao Dian

    The present HVAC equipments for the residential buildings in the Hot-summer-and-Cold-winter climate region are still at a high energy consuming level. So that the high efficiency HVAC system is an urgently need for achieving the preset government energy saving goal. With its advantage of highly sanitary, highly comfortable and uniform of temperature field, the hot-water resource floor radiation heating system has been widely accepted. This paper has put forward a new way in air-conditioning, which combines the fresh-air supply unit and such floor radiation system for the dehumidification and cooling in summer or heating in winter. By analyze its advantages and limitations, we found that this so called Cooling/ Heating Floor AC System can improve the IAQ of residential building while keep high efficiency quality. We also recommend a methodology for the HVAC system designing, which will ensure the reduction of energy cost of users.

  20. Manually operated coded switch

    DOEpatents

    Barnette, Jon H.

    1978-01-01

    The disclosure relates to a manually operated recodable coded switch in which a code may be inserted, tried and used to actuate a lever controlling an external device. After attempting a code, the switch's code wheels must be returned to their zero positions before another try is made.

  1. Quantum cryptography without switching.

    PubMed

    Weedbrook, Christian; Lance, Andrew M; Bowen, Warwick P; Symul, Thomas; Ralph, Timothy C; Lam, Ping Koy

    2004-10-22

    We propose a new coherent state quantum key distribution protocol that eliminates the need to randomly switch between measurement bases. This protocol provides significantly higher secret key rates with increased bandwidths than previous schemes that only make single quadrature measurements. It also offers the further advantage of simplicity compared to all previous protocols which, to date, have relied on switching.

  2. Reflective HTS switch

    DOEpatents

    Martens, Jon S.; Hietala, Vincent M.; Hohenwarter, Gert K. G.

    1994-01-01

    A HTS switch includes a HTS conductor for providing a superconducting path for an electrical signal and an serpentine wire actuator for controllably heating a portion of the conductor sufficiently to cause that portion to have normal, and not superconducting, resistivity. Mass of the portion is reduced to decrease switching time.

  3. Reflective HTS switch

    DOEpatents

    Martens, J.S.; Hietala, V.M.; Hohenwarter, G.K.G.

    1994-09-27

    A HTS (High Temperature Superconductor) switch includes a HTS conductor for providing a superconducting path for an electrical signal and an serpentine wire actuator for controllably heating a portion of the conductor sufficiently to cause that portion to have normal, and not superconducting, resistivity. Mass of the portion is reduced to decrease switching time. 6 figs.

  4. From periphery to player: strategically positioning occupational therapy within the knowledge translation landscape.

    PubMed

    Cramm, Heidi; White, Catherine; Krupa, Terry

    2013-01-01

    Knowledge translation has emerged as a critical force across health research, funding, policy, and practice. Occupational therapy finds itself on the periphery of this emerging field, but opportunities specific to occupational therapy systems can facilitate a shift in which the profession develops its role as a key player. As occupational therapy increasingly recognizes the essential role of knowledge translation in health care, strategic action to create knowledge translator roles, technology, resources, opportunities, and communities of practice will be needed to align occupational therapy academic and health care systems with knowledge translation imperatives that increasingly shape the health care landscape. PMID:23245790

  5. Thermal history of the periphery of the Junggar Basin, Northwestern China

    USGS Publications Warehouse

    King, J.D.; Yang, J.; Pu, F.

    1994-01-01

    Geochemical analysis of rock core samples show that the basin periphery has experienced low thermal stress; present-day heat flows are in the range of 25-35 mW/m2 and have not been significantly higher than the worldwide mean of approx. 63 mW/m2 since the mid-Permian. Present day heat flows were determined from corrected borehole temperatures and rock thermal conductivities. Paleo-heat flows were determined by first-order reaction kinetic modeling of several geochemical paleothermometers (vitrinite reflectance, clay mineral diagenesis and relative proportions of sterane and hopane biological marker diastereomers). ?? 1994.

  6. Erected mirror optical switch

    DOEpatents

    Allen, James J.

    2005-06-07

    A microelectromechanical (MEM) optical switching apparatus is disclosed that is based on an erectable mirror which is formed on a rotatable stage using surface micromachining. An electrostatic actuator is also formed on the substrate to rotate the stage and mirror with a high angular precision. The mirror can be erected manually after fabrication of the device and used to redirect an incident light beam at an arbitrary angel and to maintain this state in the absence of any applied electrical power. A 1.times.N optical switch can be formed using a single rotatable mirror. In some embodiments of the present invention, a plurality of rotatable mirrors can be configured so that the stages and mirrors rotate in unison when driven by a single micromotor thereby forming a 2.times.2 optical switch which can be used to switch a pair of incident light beams, or as a building block to form a higher-order optical switch.

  7. Nanoscale memristive radiofrequency switches

    NASA Astrophysics Data System (ADS)

    Pi, Shuang; Ghadiri-Sadrabadi, Mohammad; Bardin, Joseph C.; Xia, Qiangfei

    2015-06-01

    Radiofrequency switches are critical components in wireless communication systems and consumer electronics. Emerging devices include switches based on microelectromechanical systems and phase-change materials. However, these devices suffer from disadvantages such as large physical dimensions and high actuation voltages. Here we propose and demonstrate a nanoscale radiofrequency switch based on a memristive device. The device can be programmed with a voltage as low as 0.4 V and has an ON/OFF conductance ratio up to 1012 with long state retention. We measure the radiofrequency performance of the switch up to 110 GHz and demonstrate low insertion loss (0.3 dB at 40 GHz), high isolation (30 dB at 40 GHz), an average cutoff frequency of 35 THz and competitive linearity and power-handling capability. Our results suggest that, in addition to their application in memory and computing, memristive devices are also a leading contender for radiofrequency switch applications.

  8. Avalanche photoconductive switching

    SciTech Connect

    Pocha, M.D.; Druce, R.L.; Wilson, M.J.; Hofer, W.W.

    1989-01-01

    This paper describes work being done at Lawrence Livermore National Laboratory on the avalanche mode of operation of laser triggered photoconductive switches. We have been able to generate pulses with amplitudes of 2 kV--35 kV and rise times of 300--500 ps, and with a switching gain (energy of output electrical pulse vs energy of trigger optical pulse) of 10{sup 3} to over 10{sup 5}. Switches with two very different physical configurations and with two different illumination wavelengths (1.06 {mu}m, 890 nm) exhibit very similar behavior. The avalanche switching behavior, therefore, appears to be related to the material parameters rather than the optical wavelength or switch geometry. Considerable further work needs to be done to fully characterize and understand this mode of operation. 3 refs., 6 figs.

  9. A Novel Soft Switching PWM Power Frequency Converter with Non DC Smoothing Filter Link for Consumer High Frequency Induction Heating

    NASA Astrophysics Data System (ADS)

    Sugimura, Hisayuki; Muraoka, Hidekazu; Hiraki, Eiji; Hirota, Izuo; Yasui, Kenji; Omori, Hideki; Lee, Hyun-Woo; Nakaoka, Mutsuo

    In this paper, high frequency power converter without DC smoothing electrolytic capacitor filter link which convert the 100V/200Vrms and 60Hz single phase utility frequency AC power into a high frequency AC. This proposed high frequency AC power converter without electrolytic capacitor filter can operate under a principle of soft switching PWM based on a lossless capacitor snubber is proposed and demonstrated for consumer high frequency induction heating (IH). In particular, this high frequency power converter capable of producing a high frequency AC more than 20kHz is developed for consumer IH applications as hot water producer and steamer based on the specially designed spiral type IH-Dual Packs Heater (DPH), which includes the dual mode pulse modulation control scheme based on soft switching PWM for high output power setting and commercial frequency AC zero voltage soft switching pulse density modulation (PDM) for low output power settings. This developed high frequency power frequency converter using trench gate IGBTs is clarified on the basis of experimental and simulation results for its circuit operation of the utility frequency AC to high frequency AC frequency PWM power converter without the electrolytic capacitor bank DC filter link for the IH hot water and IH steamer. These IH appliances are based upon an innovative electromagnetic IH-DPH for fluid heating as heat exchanger in consumer pipeline. Finally, its power regulation characteristics, power conversion efficiency and harmonic current components characteristics including power factor in utility AC grid side are evaluated and discussed from an experimental point of view. The practical effectiveness of this utility frequency AC to high frequency AC soft switching high power frequency converter defined conveniently as high frequency soft switching cyclo-inverter is proved as one of the important products effective for next generation IH application all electricity power utilizations.

  10. Sperm-induced calcium oscillations of human oocytes show distinct features in oocyte center and periphery.

    PubMed

    Tesarik, J; Sousa, M; Mendoza, C

    1995-06-01

    Temporal and spatial characteristics of explosive periodic increases (spikes) of intracellular free Ca2+ concentration ([Ca2+]i) induced by sperm in human oocytes (Ca2+ oscillations) were analyzed by confocal laser scanning microscopy and compared to Ca2+ oscillations induced in oocytes by the thiol reagent thimerosal. During the steady-state period of sperm-induced Ca2+ oscillations, each individual [Ca2+]i spike invariably began from a focus in oocyte periphery and spread throughout the entire peripheral region before propagating to the central ooplasm. This peripheral Ca2+ wave was immediately followed by an explosive [Ca2+]i increase in the central ooplasm. However, this central [Ca2+]i rise only peaked when [Ca2+]i in the peripheral ooplasm was already on the decline. Moreover, the peak [Ca2+]i values were always considerably higher in the oocyte center than in the periphery. In contrast, thimerosal-induced Ca2+ oscillations did not show this particular form of propagation. These data show that sperm-induced Ca2+ oscillations have a unique pattern of spatial dynamics and suggest that the bulk of Ca2+ mobilized during each spike is released from stores that have a relatively high threshold for Ca(2+)-induced Ca2+ release (CICR). These stores are poorly developed, if not absent, in the oocyte cortex, and CICR from them is triggered by previous CICR from another type of store with a lower threshold that are preferentially located in the oocyte cortex and act as a detonator.

  11. Density-based and transport-based core-periphery structures in networks

    NASA Astrophysics Data System (ADS)

    Lee, Sang Hoon; Cucuringu, Mihai; Porter, Mason A.

    2014-03-01

    Networks often possess mesoscale structures, and studying them can yield insights into both structure and function. It is most common to study community structure, but numerous other types of mesoscale structures also exist. In this paper, we examine core-periphery structures based on both density and transport. In such structures, core network components are well-connected both among themselves and to peripheral components, which are not well-connected to anything. We examine core-periphery structures in a wide range of examples of transportation, social, and financial networks—including road networks in large urban areas, a rabbit warren, a dolphin social network, a European interbank network, and a migration network between counties in the United States. We illustrate that a recently developed transport-based notion of node coreness is very useful for characterizing transportation networks. We also generalize this notion to examine core versus peripheral edges, and we show that the resulting diagnostic is also useful for transportation networks. To examine the properties of transportation networks further, we develop a family of generative models of roadlike networks. We illustrate the effect of the dimensionality of the embedding space on transportation networks, and we demonstrate that the correlations between different measures of coreness can be very different for different types of networks.

  12. A hardware model of the auditory periphery to transduce acoustic signals into neural activity

    PubMed Central

    Tateno, Takashi; Nishikawa, Jun; Tsuchioka, Nobuyoshi; Shintaku, Hirofumi; Kawano, Satoyuki

    2013-01-01

    To improve the performance of cochlear implants, we have integrated a microdevice into a model of the auditory periphery with the goal of creating a microprocessor. We constructed an artificial peripheral auditory system using a hybrid model in which polyvinylidene difluoride was used as a piezoelectric sensor to convert mechanical stimuli into electric signals. To produce frequency selectivity, the slit on a stainless steel base plate was designed such that the local resonance frequency of the membrane over the slit reflected the transfer function. In the acoustic sensor, electric signals were generated based on the piezoelectric effect from local stress in the membrane. The electrodes on the resonating plate produced relatively large electric output signals. The signals were fed into a computer model that mimicked some functions of inner hair cells, inner hair cell–auditory nerve synapses, and auditory nerve fibers. In general, the responses of the model to pure-tone burst and complex stimuli accurately represented the discharge rates of high-spontaneous-rate auditory nerve fibers across a range of frequencies greater than 1 kHz and middle to high sound pressure levels. Thus, the model provides a tool to understand information processing in the peripheral auditory system and a basic design for connecting artificial acoustic sensors to the peripheral auditory nervous system. Finally, we discuss the need for stimulus control with an appropriate model of the auditory periphery based on auditory brainstem responses that were electrically evoked by different temporal pulse patterns with the same pulse number. PMID:24324432

  13. A hardware model of the auditory periphery to transduce acoustic signals into neural activity.

    PubMed

    Tateno, Takashi; Nishikawa, Jun; Tsuchioka, Nobuyoshi; Shintaku, Hirofumi; Kawano, Satoyuki

    2013-01-01

    To improve the performance of cochlear implants, we have integrated a microdevice into a model of the auditory periphery with the goal of creating a microprocessor. We constructed an artificial peripheral auditory system using a hybrid model in which polyvinylidene difluoride was used as a piezoelectric sensor to convert mechanical stimuli into electric signals. To produce frequency selectivity, the slit on a stainless steel base plate was designed such that the local resonance frequency of the membrane over the slit reflected the transfer function. In the acoustic sensor, electric signals were generated based on the piezoelectric effect from local stress in the membrane. The electrodes on the resonating plate produced relatively large electric output signals. The signals were fed into a computer model that mimicked some functions of inner hair cells, inner hair cell-auditory nerve synapses, and auditory nerve fibers. In general, the responses of the model to pure-tone burst and complex stimuli accurately represented the discharge rates of high-spontaneous-rate auditory nerve fibers across a range of frequencies greater than 1 kHz and middle to high sound pressure levels. Thus, the model provides a tool to understand information processing in the peripheral auditory system and a basic design for connecting artificial acoustic sensors to the peripheral auditory nervous system. Finally, we discuss the need for stimulus control with an appropriate model of the auditory periphery based on auditory brainstem responses that were electrically evoked by different temporal pulse patterns with the same pulse number. PMID:24324432

  14. Optical Circuit Switched Protocol

    NASA Technical Reports Server (NTRS)

    Monacos, Steve P. (Inventor)

    2000-01-01

    The present invention is a system and method embodied in an optical circuit switched protocol for the transmission of data through a network. The optical circuit switched protocol is an all-optical circuit switched network and includes novel optical switching nodes for transmitting optical data packets within a network. Each optical switching node comprises a detector for receiving the header, header detection logic for translating the header into routing information and eliminating the header, and a controller for receiving the routing information and configuring an all optical path within the node. The all optical path located within the node is solely an optical path without having electronic storage of the data and without having optical delay of the data. Since electronic storage of the header is not necessary and the initial header is eliminated by the first detector of the first switching node. multiple identical headers are sent throughout the network so that subsequent switching nodes can receive and read the header for setting up an optical data path.

  15. Photoconductive switch package

    DOEpatents

    Ca[rasp, George J

    2013-10-22

    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.

  16. Photoconductive switch package

    SciTech Connect

    Caporaso, George J.

    2015-10-27

    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.

  17. SPARK GAP SWITCH

    DOEpatents

    Neal, R.B.

    1957-12-17

    An improved triggered spark gap switch is described, capable of precisely controllable firing time while switching very large amounts of power. The invention in general comprises three electrodes adjustably spaced and adapted to have a large potential impressed between the outer electrodes. The central electrode includes two separate elements electrically connected togetaer and spaced apart to define a pair of spark gaps between the end electrodes. Means are provided to cause the gas flow in the switch to pass towards the central electrode, through a passage in each separate element, and out an exit disposed between the two separate central electrode elements in order to withdraw ions from the spark gap.

  18. Solid state switch

    DOEpatents

    Merritt, B.T.; Dreifuerst, G.R.

    1994-07-19

    A solid state switch, with reverse conducting thyristors, is designed to operate at 20 kV hold-off voltage, 1,500 A peak, 1.0 [mu]s pulsewidth, and 4,500 pps, to replace thyratrons. The solid state switch is more reliable, more economical, and more easily repaired. The switch includes a stack of circuit card assemblies, a magnetic assist and a trigger chassis. Each circuit card assembly contains a reverse conducting thyristor, a resistor capacitor network, and triggering circuitry. 6 figs.

  19. ACS CCD Stability Monitor

    NASA Astrophysics Data System (ADS)

    Grogin, Norman

    2012-10-01

    A moderately crowded stellar field in the cluster 47 Tuc {6 arcmin West of the cluster core} is observed every four months with the WFC. The first visit exercises the full suite of broad and narrow band imaging filters and sub-array modes; following visits observe with only the six most popular Cycle 18 filters in full-frame mode. The positions and magnitudes of objects will be used to monitor local and large scale variations in the plate scale and the sensitivity of the detectors and to derive an independent measure of the detector CTE. One exposure in each sub-array mode with the WFC will allow us to verify that photometry obtained in full-frame and in sub-array modes are repeatable to better than 1%. This test is important for the ACS Photometric Cross-Calibration program, which uses sub-array exposures. This program may receive additional orbits to investigate ORIENT-dependent geometric distortion, which motivates the ORIENT and BETWEEN requirement on the first visit.

  20. AC photovoltaic module magnetic fields

    SciTech Connect

    Jennings, C.; Chang, G.J.; Reyes, A.B.; Whitaker, C.M.

    1997-12-31

    Implementation of alternating current (AC) photovoltaic (PV) modules, particularly for distributed applications such as PV rooftops and facades, may be slowed by public concern about electric and magnetic fields (EMF). This paper documents magnetic field measurements on an AC PV module, complementing EMF research on direct-current PV modules conducted by PG and E in 1993. Although not comprehensive, the PV EMF data indicate that 60 Hz magnetic fields (the EMF type of greatest public concern) from PV modules are comparable to, or significantly less than, those from household appliances. Given the present EMF research knowledge, AC PV module EMF may not merit considerable concern.

  1. Towards an AC-MOT of CaF

    NASA Astrophysics Data System (ADS)

    Anderegg, Loic; Chae, Eunmi; Ravi, Aakash; Augenbraun, Benjamin; Hemmerling, Boerge; Drayna, Garrett; Hutzler, Nicholas; Collopy, Alejandra; Wu, Yewei; Ding, Shiqian; Ye, Jun; Ketterle, Wolfgang; Doyle, John

    2016-05-01

    Ultra-cold diatomic molecules have rich prospects as candidates to study controlled ultra-cold chemistry, strongly correlated systems and precision measurements. They are also considered as possible qubits in quantum computing and simulation schemes. We report on progress towards loading CaF into a molecular magneto-optical trap (MOT). An AC-MOT will be used to actively remix magnetic dark states via both polarization and magnetic field switching. In order to load a molecular MOT, we have successfully laser slowed a CaF beam to near the expected capture velocity. We describe our AC-MOT apparatus, which is designed to co-trap CaF and Li. We outline our planned study of CaF-Li collisions to explore the feasibility of sympathetically cooling molecules to ultra-cold temperatures.

  2. Switching and stopping antidepressants.

    PubMed

    Keks, Nicholas; Hope, Judy; Keogh, Simone

    2016-06-01

    Switching from one antidepressant to another is frequently indicated due to an inadequate treatment response or unacceptable adverse effects. All antidepressant switches must be carried out cautiously and under close observation. Conservative switching strategies involve gradually tapering the first antidepressant followed by an adequate washout period before the new antidepressant is started. This can take a long time and include periods of no treatment with the risk of potentially life-threatening exacerbations of illness. Clinical expertise is needed for more rapid or cross-taper switching as drug toxicity, including serotonin syndrome, may result from inappropriate co-administration of antidepressants. Some antidepressants must not be combined. Antidepressants can cause withdrawal syndromes if discontinued abruptly after prolonged use. Relapse and exacerbation of depression can also occur. Gradual dose reduction over days to weeks reduces the risk and severity of complications. PMID:27346915

  3. An optical switch

    DOEpatents

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

    1987-04-30

    The invention is a gas mixture for a diffuse discharge switch having an electron attaching gas wherein electron attachment is brought about by indirect excitation of molecules to long live states by exposure to laser light. 3 figs.

  4. Switching and stopping antidepressants

    PubMed Central

    Keks, Nicholas; Hope, Judy; Keogh, Simone

    2016-01-01

    SUMMARY Switching from one antidepressant to another is frequently indicated due to an inadequate treatment response or unacceptable adverse effects. All antidepressant switches must be carried out cautiously and under close observation. Conservative switching strategies involve gradually tapering the first antidepressant followed by an adequate washout period before the new antidepressant is started. This can take a long time and include periods of no treatment with the risk of potentially life-threatening exacerbations of illness. Clinical expertise is needed for more rapid or cross-taper switching as drug toxicity, including serotonin syndrome, may result from inappropriate co-administration of antidepressants. Some antidepressants must not be combined. Antidepressants can cause withdrawal syndromes if discontinued abruptly after prolonged use. Relapse and exacerbation of depression can also occur. Gradual dose reduction over days to weeks reduces the risk and severity of complications. PMID:27346915

  5. Plasmonic enhanced ultrafast switch.

    SciTech Connect

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

    2009-09-01

    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.

  6. Irreversible magnetic switch

    SciTech Connect

    Karnowsky, M.M.; Yost, F.G.

    1991-12-31

    This invention is comprised of an irreversible magnetic switch containing a ferromagnetic amorphous metal having a predetermined crystallization temperature in its inductor magnetic path. With the incorporation of such material, the magnetic properties after cooling from a high temperature excursion above its crystallization temperature are only a fraction of the original value. The difference is used to provide a safety feature in the magnetic switch.

  7. High Power Switching Transistor

    NASA Technical Reports Server (NTRS)

    Hower, P. L.; Kao, Y. C.; Carnahan, D. C.

    1983-01-01

    Improved switching transistors handle 400-A peak currents and up to 1,200 V. Using large diameter silicon wafers with twice effective area as D60T, form basis for D7 family of power switching transistors. Package includes npn wafer, emitter preform, and base-contact insert. Applications are: 25to 50-kilowatt high-frequency dc/dc inverters, VSCF converters, and motor controllers for electrical vehicles.

  8. Cygnus Water Switch Jitter

    SciTech Connect

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

    2008-03-01

    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.

  9. Optical shutter switching matrix

    NASA Technical Reports Server (NTRS)

    Grove, Charles H.

    1991-01-01

    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.

  10. Shunt switched resistor regulator with diode snubber

    SciTech Connect

    Ekstrand, J.

    1989-03-21

    This patent describes a shunt switched resistor regulator power supply for supplying a variable amount of power to a load comprising: a rectifier means for accepting AC input voltage and converting it to DC output voltage at a positive and a negative terminal; first, second, third, and fourth nodes wherein the first and the fourth nodes are coupled to the positive and negative terminals, respectively; a current limiting resistor coupled between the first and second nodes; a capacitor coupled between the second and fourth nodes; a resistor having parasitic inductance coupled between the second and third nodes; a switch coupled between the third and fourth nodes; and a diode having its anode coupled to the third node and having its cathode coupled to the second node; means coupled to the load terminals for sensing the power being delivered to the load and for controlling the switch to have a duty cycle which results in the desired load current flowing through and a desired voltage appearing across the load in accordance with control input signals received at a control input.

  11. Power Electronic Transformer based Three-Phase PWM AC Drives

    NASA Astrophysics Data System (ADS)

    Basu, Kaushik

    A Transformer is used to provide galvanic isolation and to connect systems at different voltage levels. It is one of the largest and most expensive component in most of the high voltage and high power systems. Its size is inversely proportional to the operating frequency. The central idea behind a power electronic transformer (PET) also known as solid state transformer is to reduce the size of the transformer by increasing the frequency. Power electronic converters are used to change the frequency of operation. Steady reduction in the cost of the semiconductor switches and the advent of advanced magnetic materials with very low loss density and high saturation flux density implies economic viability and feasibility of a design with high power density. Application of PET is in generation of power from renewable energy sources, especially wind and solar. Other important application include grid tied inverters, UPS e.t.c. In this thesis non-resonant, single stage, bi-directional PET is considered. The main objective of this converter is to generate adjustable speed and magnitude pulse width modulated (PWM) ac waveforms from an ac or dc grid with a high frequency ac link. The windings of a high frequency transformer contains leakage inductance. Any switching transition of the power electronic converter connecting the inductive load and the transformer requires commutation of leakage energy. Commutation by passive means results in power loss, decrease in the frequency of operation, distortion in the output voltage waveform, reduction in reliability and power density. In this work a source based partially loss-less commutation of leakage energy has been proposed. This technique also results in partial soft-switching. A series of converters with novel PWM strategies have been proposed to minimize the frequency of leakage inductance commutation. These PETs achieve most of the important features of modern PWM ac drives including 1) Input power factor correction, 2) Common

  12. A PWM transistor inverter for an ac electric vehicle drive

    NASA Technical Reports Server (NTRS)

    Slicker, J. M.

    1981-01-01

    A prototype system consisting of closely integrated motor, inverter, and transaxle has been built in order to demonstrate the feasibility of a three-phase ac transistorized inverter for electric vehicle applications. The microprocessor-controlled inverter employs monolithic power transistors to drive an oil-cooled, three-phase induction traction motor at a peak output power of 30 kW from a 144 V battery pack. Transistor safe switching requirements are discussed, and a circuit is presented for recovering trapped snubber inductor energy at transistor turn-off.

  13. Finding a stabilising switching law for switching nonlinear models

    NASA Astrophysics Data System (ADS)

    Lendek, Zs.; Raica, P.; Lauber, J.; Guerra, T. M.

    2016-09-01

    This paper considers the stabilisation of switching nonlinear models by switching between the subsystems. We assume that arbitrary switching between two subsystems is possible once a subsystem has been active for a predefined number of samples. We use a Takagi-Sugeno representation of the models and a switching Lyapunov function is employed to develop sufficient stability conditions. If the conditions are satisfied, we construct a switching law that stabilises the system. The application of the conditions is illustrated in several examples.

  14. Canada's Neglected Tropical Disease Research Network: Who's in the Core—Who's on the Periphery?

    PubMed Central

    Phillips, Kaye; Kohler, Jillian Clare; Pennefather, Peter; Thorsteinsdottir, Halla; Wong, Joseph

    2013-01-01

    Background This study designed and applied accessible yet systematic methods to generate baseline information about the patterns and structure of Canada's neglected tropical disease (NTD) research network; a network that, until recently, was formed and functioned on the periphery of strategic Canadian research funding. Methodology Multiple methods were used to conduct this study, including: (1) a systematic bibliometric procedure to capture archival NTD publications and co-authorship data; (2) a country-level “core-periphery” network analysis to measure and map the structure of Canada's NTD co-authorship network including its size, density, cliques, and centralization; and (3) a statistical analysis to test the correlation between the position of countries in Canada's NTD network (“k-core measure”) and the quantity and quality of research produced. Principal Findings Over the past sixty years (1950–2010), Canadian researchers have contributed to 1,079 NTD publications, specializing in Leishmania, African sleeping sickness, and leprosy. Of this work, 70% of all first authors and co-authors (n = 4,145) have been Canadian. Since the 1990s, however, a network of international co-authorship activity has been emerging, with representation of researchers from 62 different countries; largely researchers from OECD countries (e.g. United States and United Kingdom) and some non-OECD countries (e.g. Brazil and Iran). Canada has a core-periphery NTD international research structure, with a densely connected group of OECD countries and some African nations, such as Uganda and Kenya. Sitting predominantly on the periphery of this research network is a cluster of 16 non-OECD nations that fall within the lowest GDP percentile of the network. Conclusion/Significance The publication specialties, composition, and position of NTD researchers within Canada's NTD country network provide evidence that while Canadian researchers currently remain the overall gatekeepers of the

  15. Low inductance gas switching.

    SciTech Connect

    Chavez, Ray; Harjes, Henry Charles III; Wallace, Zachariah; Elizondo, Juan E.

    2007-10-01

    The laser trigger switch (LTS) is a key component in ZR-type pulsed power systems. In ZR, the pulse rise time through the LTS is > 200 ns and additional stages of pulse compression are required to achieve the desired <100 ns rise time. The inductance of the LTS ({approx}500nH) in large part determines the energy transfer time through the switch and there is much to be gained in improving system performance and reducing system costs by reducing this inductance. The current path through the cascade section of the ZR LTS is at a diameter of {approx} 6-inches which is certainly not optimal from an inductance point of view. The LTS connects components of much greater diameter (typically 4-5 feet). In this LDRD the viability of switch concepts in which the diameter of cascade section is greatly increased have been investigated. The key technical question to be answered was, will the desired multi-channel behavior be maintained in a cascade section of larger diameter. This LDRD proceeded in 2 distinct phases. The original plan for the LDRD was to develop a promising switch concept and then design, build, and test a moderate scale switch which would demonstrate the key features of the concept. In phase I, a switch concept which meet all electrical design criteria and had a calculated inductance of 150 nH was developed. A 1.5 MV test switch was designed and fabrication was initiated. The LDRD was then redirected due to budgetary concerns. The fabrication of the switch was halted and the focus of the LDRD was shifted to small scale experiments designed to answer the key technical question concerning multi-channel behavior. In phase II, the Multi-channel switch test bed (MCST) was designed and constructed. The purpose of MCST was to provide a versatile, fast turn around facility for the study the multi-channel electrical breakdown behavior of a ZR type cascade switch gap in a parameter space near that of a ZR LTS. Parameter scans on source impedance, gap tilt, gap spacing and

  16. Visualizing the molecular sociology at the HeLa cell nuclear periphery.

    PubMed

    Mahamid, Julia; Pfeffer, Stefan; Schaffer, Miroslava; Villa, Elizabeth; Danev, Radostin; Cuellar, Luis Kuhn; Förster, Friedrich; Hyman, Anthony A; Plitzko, Jürgen M; Baumeister, Wolfgang

    2016-02-26

    The molecular organization of eukaryotic nuclear volumes remains largely unexplored. Here we combined recent developments in cryo-electron tomography (cryo-ET) to produce three-dimensional snapshots of the HeLa cell nuclear periphery. Subtomogram averaging and classification of ribosomes revealed the native structure and organization of the cytoplasmic translation machinery. Analysis of a large dynamic structure-the nuclear pore complex-revealed variations detectable at the level of individual complexes. Cryo-ET was used to visualize previously elusive structures, such as nucleosome chains and the filaments of the nuclear lamina, in situ. Elucidation of the lamina structure provides insight into its contribution to metazoan nuclear stiffness. PMID:26917770

  17. Crowding by a single bar: probing pattern recognition mechanisms in the visual periphery.

    PubMed

    Põder, Endel

    2014-11-06

    Whereas visual crowding does not greatly affect the detection of the presence of simple visual features, it heavily inhibits combining them into recognizable objects. Still, crowding effects have rarely been directly related to general pattern recognition mechanisms. In this study, pattern recognition mechanisms in visual periphery were probed using a single crowding feature. Observers had to identify the orientation of a rotated T presented briefly in a peripheral location. Adjacent to the target, a single bar was presented. The bar was either horizontal or vertical and located in a random direction from the target. It appears that such a crowding bar has very strong and regular effects on the identification of the target orientation. The observer's responses are determined by approximate relative positions of basic visual features; exact image-based similarity to the target is not important. A version of the "standard model" of object recognition with second-order features explains the main regularities of the data.

  18. A radiation hard vacuum switch

    DOEpatents

    Boettcher, G.E.

    1988-07-19

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction. 3 figs.

  19. Surfatron acceleration of protons by an electromagnetic wave at the heliosphere periphery

    SciTech Connect

    Loznikov, V. M. Erokhin, N. S.; Zol’nikova, N. N.; Mikhailovskaya, L. A.

    2013-10-15

    The trapping and subsequent efficient surfatron acceleration of weakly relativistic protons by an electromagnetic wave propagating across an external magnetic field in plasma at the heliosphere periphery is considered. The problem is reduced to analysis of a second-order time-dependent nonlinear equation for the wave phase on the particle trajectory. The conditions of proton trapping by the wave, the dynamics of the components of the particle momentum and velocity, the structure of the phase plane, the particle trajectories, and the dependence of the acceleration rate on initial parameters of the problem are analyzed. The asymptotic behavior of the characteristics of accelerated particles for the heliosphere parameters is investigated. The optimum conditions for surfatron acceleration of protons by an electromagnetic wave are discussed. It is demonstrated that the experimentally observed deviation of the spectra of cosmic-ray protons from standard power-law dependences can be caused by the surfatron mechanism. It is shown that protons with initial energies of several GeV can be additionally accelerated in the heliosphere (the region located between the shock front of the solar wind and the heliopause at distances of about 100 astronomical units (a.u.) from the Sun) up to energies on the order of several thousands of GeV. In order to explain the proton spectra in the energy range of ∼20–500 GeV, a two-component phenomenological model is proposed. The first component corresponds to the constant (in this energy range) galactic contribution, while the second (variable) component corresponds to the heliospheric contribution, which appears due to the additional acceleration of soft cosmic-ray protons at the heliosphere periphery. Variations in the proton spectra measured on different time scales between 1992 and 2008 in the energy range from several tens to several hundred GeV, as well as the dependence of these spectra on the heliospheric weather, can be explained

  20. Esc1, a Nuclear Periphery Protein Required for Sir4-Based Plasmid Anchoring and Partitioning

    PubMed Central

    Andrulis, Erik D.; Zappulla, David C.; Ansari, Athar; Perrod, Severine; Laiosa, Catherine V.; Gartenberg, Marc R.; Sternglanz, Rolf

    2002-01-01

    A targeted silencing screen was performed to identify yeast proteins that, when tethered to a telomere, suppress a telomeric silencing defect caused by truncation of Rap1. A previously uncharacterized protein, Esc1 (establishes silent chromatin), was recovered, in addition to well-characterized proteins Rap1, Sir1, and Rad7. Telomeric silencing was slightly decreased in Δesc1 mutants, but silencing of the HM loci was unaffected. On the other hand, targeted silencing by various tethered proteins was greatly weakened in Δesc1 mutants. Two-hybrid analysis revealed that Esc1 and Sir4 interact via a 34-amino-acid portion of Esc1 (residues 1440 to 1473) and a carboxyl-terminal domain of Sir4 known as PAD4 (residues 950 to 1262). When tethered to DNA, this Sir4 domain confers efficient partitioning to otherwise unstable plasmids and blocks the ability of bound DNA segments to rotate freely in vivo. Here, both phenomena were shown to require ESC1. Sir protein-mediated partitioning of a telomere-based plasmid also required ESC1. Fluorescence microscopy of cells expressing green fluorescent protein (GFP)-Esc1 showed that the protein localized to the nuclear periphery, a region of the nucleus known to be functionally important for silencing. GFP-Esc1 localization, however, was not entirely coincident with telomeres, the nucleolus, or nuclear pore complexes. Our data suggest that Esc1 is a component of a redundant pathway that functions to localize silencing complexes to the nuclear periphery. PMID:12417731

  1. Estrogenic support of motoneuron dendritic growth via the neuromuscular periphery in a sexually dimorphic motor system.

    PubMed

    Nowacek, Ari S; Sengelaub, Dale R

    2006-08-01

    The lumbar spinal cord of rats contains the sexually dimorphic, steroid-sensitive spinal nucleus of the bulbocavernosus (SNB). In males, the growth of SNB dendrites is steroid-dependent: dendrites fail to grow after castration, but grow in castrates treated with androgens or estrogens. Blocking estradiol synthesis or estrogen receptors in gonadally intact males attenuates SNB dendritic growth, suggesting that estrogens are required and must be able to act at their receptors to support normal masculine dendritic growth. However, SNB motoneurons do not accumulate estrogens, suggesting that estrogens act indirectly to support SNB dendritic growth. In this experiment, we examined whether local estrogen action in the neuromuscular periphery was involved in the postnatal development of SNB motoneurons. Motoneuron morphology was assessed in gonadally intact and castrated males. Gonadally intact males were left untreated or given either blank or tamoxifen implants sutured to the target musculature, or tamoxifen interscapular implants. Castrated males were left untreated or were given estradiol by muscle or interscapular implants or systemic injection during the period of SNB dendritic growth. At postnatal day 28, when SNB dendritic length is normally maximal, SNB motoneurons were retrogradely labeled with cholera toxin-HRP and reconstructed in three dimensions. While interscapular tamoxifen implants were ineffective, blocking estrogen receptors at the target musculature resulted in attenuation of SNB dendritic growth. In contrast, while interscapular implants of estradiol were ineffective, local treatment with estradiol at the target musculature in castrated males resulted in masculinization of dendritic growth. Thus, estrogens may act by an indirect action in the neuromuscular periphery to support SNB dendritic growth.

  2. Vibration rendering on a thin plate with actuator array at the periphery

    NASA Astrophysics Data System (ADS)

    Woo, Jung-Han; Ih, Jeong-Guon

    2015-08-01

    Vibrations are rendered on the display panel of a mobile electronic device to transfer a tactile sensation to users. Because important electronic components are usually positioned in the central part of the devices, the only practical choice for actuator location is the periphery of the panel although the periphery is not the advantageous position for the excitation. As the basic principle to generate a rendered vibration pattern, two methods to determine the contributions of modes, viz., eigenfunction superposition or traveling wave control method, are implemented individually. The purpose is to generate a pattern of vibration amplitudes that can be felt by fingertip in the hot zone but not in the cold zone, which is outside the hot zone. General inverse methods are applied to obtain the actuator weightings for achieving the target pattern. Proper weighting for both amplitude and phase for each actuator in the array is determined by the relationship between modes or velocity responses and input signals of actuators. Two methods are implemented individually on the display panel of a commercial tablet computer using an array of moving-coil actuators, and the responses on the panel are measured. Performance index referred to as success ratio for evaluating satisfaction of target field constraints is proposed considering the different thresholds of vibration sensation. Reasonable fulfillment of achieving the target vibration pattern is observed experimentally. The success ratio is more than 86% by using the eigenfunction superposition, and more than 97% by using the traveling wave control for rendering 2×2 and 3×3 section.

  3. Energy losses in switches

    SciTech Connect

    Martin, T.H.; Seamen, J.F.; Jobe, D.O.

    1993-07-01

    The authors experiments show energy losses between 2 and 10 times that of the resistive time predictions. The experiments used hydrogen, helium, air, nitrogen, SF{sub 6} polyethylene, and water for the switching dielectric. Previously underestimated switch losses have caused over predicting the accelerator outputs. Accurate estimation of these losses is now necessary for new high-efficiency pulsed power devices where the switching losses constitute the major portion of the total energy loss. They found that the switch energy losses scale as (V{sub peak}I{sub peak}){sup 1.1846}. When using this scaling, the energy losses in any of the tested dielectrics are almost the same. This relationship is valid for several orders of magnitude and suggested a theoretical basis for these results. Currents up to .65 MA, with voltages to 3 MV were applied to various gaps during these experiments. The authors data and the developed theory indicates that the switch power loss continues for a much longer time than the resistive time, with peak power loss generally occurring at peak current in a ranging discharge instead of the early current time. All of the experiments were circuit code modeled after developing a new switch loss version based on the theory. The circuit code predicts switch energy loss and peak currents as a function of time. During analysis of the data they noticed slight constant offsets between the theory and data that depended on the dielectric. They modified the plasma conductivity for each tested dielectric to lessen this offset.

  4. Fast high-temperature superconductor switch for high current applications

    SciTech Connect

    Solovyov, VF; Li, Q

    2013-07-15

    Reversible operation of a high current superconductor switch based on the quench of high-resistance second generation high temperature superconducting wire is demonstrated. The quench is induced by a burst of an ac field generated by an inductively coupled radio-frequency coil. The switch makes a superconducting-to-normal transition within 5 ms and also has a rapid recovery to the superconducting state. The device has potential applications as an active current limiter or as a storage switch for superconducting magnetic energy storage systems. Operation in a full flux penetration/flow regime can effectively minimize the detrimental effects of the intrinsic conductor non-uniformity. (C) 2013 AIP Publishing LLC.

  5. Switching Power Universality in Unipolar Resistive Switching Memories

    PubMed Central

    Kim, Jongmin; Jung, Kyooho; Kim, Yongmin; Jo, Yongcheol; Cho, Sangeun; Woo, Hyeonseok; Lee, Seongwoo; Inamdar, A. I.; Hong, Jinpyo; Lee, Jeon-Kook; Kim, Hyungsang; Im, Hyunsik

    2016-01-01

    We investigate the resistive switching power from unipolar resistive switching current-voltage characteristics in various binary metal oxide films sandwiched by different metal electrodes, and find a universal feature (the so-called universality) in the switching power among these devices. To experimentally derive the switching power universality, systematic measurements of the switching voltage and current are performed, and neither of these correlate with one another. As the switching resistance (R) increases, the switching power (P) decreases following a power law P ∝ R−β, regardless of the device configurations. The observed switching power universality is indicative of the existence of a commonly applicable switching mechanism. The origin of the power universality is discussed based on a metallic filament model and thermo-chemical reaction. PMID:27033695

  6. Electromechanical systems with transient high power response operating from a resonant AC link

    NASA Technical Reports Server (NTRS)

    Burrows, Linda M.; Hansen, Irving G.

    1992-01-01

    The combination of an inherently robust asynchronous (induction) electrical machine with the rapid control of energy provided by a high frequency resonant AC link enables the efficient management of higher power levels with greater versatility. This could have a variety of applications from launch vehicles to all-electric automobiles. These types of systems utilize a machine which is operated by independent control of both the voltage and frequency. This is made possible by using an indirect field-oriented control method which allows instantaneous torque control in all four operating quadrants. Incorporating the AC link allows the converter in these systems to switch at the zero crossing of every half cycle of the AC waveform. This zero loss switching of the link allows rapid energy variations to be achieved without the usual frequency proportional switching loss. Several field-oriented control systems were developed by LeRC and General Dynamics Space Systems Division under contract to NASA. A description of a single motor, electromechanical actuation system is presented. Then, focus is on a conceptual design for an AC electric vehicle. This design incorporates an induction motor/generator together with a flywheel for peak energy storage. System operation and implications along with the associated circuitry are addressed. Such a system would greatly improve all-electric vehicle ranges over the Federal Urban Driving Cycle (FUD).

  7. Nucleoplasmic Lamin A/C and Polycomb group of proteins: An evolutionarily conserved interplay

    PubMed Central

    Marullo, F.; Cesarini, E.; Antonelli, L.; Gregoretti, F.; Oliva, G.; Lanzuolo, C.

    2016-01-01

    ABSTRACT Nuclear lamins are the main components of the nuclear lamina at the nuclear periphery, providing mechanical support to the nucleus. However, recent findings suggest that lamins also reside in the nuclear interior, as a distinct and dynamic pool with critical roles in transcriptional regulation. In our work we found a functional and evolutionary conserved crosstalk between Lamin A/C and the Polycomb group (PcG) of proteins, this being required for the maintenance of the PcG repressive functions. Indeed, Lamin A/C knock-down causes PcG foci dispersion and defects in PcG-mediated higher order structures, thereby leading to impaired PcG mediated transcriptional repression. By using ad-hoc algorithms for image analysis and PLA approaches we hereby show that PcG proteins are preferentially located in the nuclear interior where they interact with nucleoplasmic Lamin A/C. Taken together, our findings suggest that nuclear components, such as Lamin A/C, functionally interact with epigenetic factors to ensure the correct transcriptional program maintenance. PMID:26930442

  8. Nucleoplasmic Lamin A/C and Polycomb group of proteins: An evolutionarily conserved interplay.

    PubMed

    Marullo, F; Cesarini, E; Antonelli, L; Gregoretti, F; Oliva, G; Lanzuolo, C

    2016-04-25

    Nuclear lamins are the main components of the nuclear lamina at the nuclear periphery, providing mechanical support to the nucleus. However, recent findings suggest that lamins also reside in the nuclear interior, as a distinct and dynamic pool with critical roles in transcriptional regulation. In our work we found a functional and evolutionary conserved crosstalk between Lamin A/C and the Polycomb group (PcG) of proteins, this being required for the maintenance of the PcG repressive functions. Indeed, Lamin A/C knock-down causes PcG foci dispersion and defects in PcG-mediated higher order structures, thereby leading to impaired PcG mediated transcriptional repression. By using ad-hoc algorithms for image analysis and PLA approaches we hereby show that PcG proteins are preferentially located in the nuclear interior where they interact with nucleoplasmic Lamin A/C. Taken together, our findings suggest that nuclear components, such as Lamin A/C, functionally interact with epigenetic factors to ensure the correct transcriptional program maintenance. PMID:26930442

  9. Thermionic gas switch

    DOEpatents

    Hatch, G.L.; Brummond, W.A.; Barrus, D.M.

    1984-04-05

    The present invention is directed to an improved temperature responsive thermionic gas switch utilizing a hollow cathode and a folded emitter surface area. The folded emitter surface area of the thermionic switch substantially increases the on/off ratio by changing the conduction surface area involved in the two modes thereof. The improved switch of this invention provides an on/off ratio of 450:1 compared to the 10:1 ratio of the prior known thermionic switch, while providing for adjusting the on current. In the improved switch of this invention the conduction area is made small in the off mode, while in the on mode the conduction area is made large. This is achieved by utilizing a folded hollow cathode configuration and utilizing a folded emitter surface area, and by making the dimensions of the folds small enough so that a space charge will develop in the convolutions of the folds and suppress unignited current, thus limiting the current carrying surface in the off mode.

  10. Switching power pulse system

    DOEpatents

    Aaland, K.

    1983-08-09

    A switching system for delivering pulses of power from a source to a load using a storage capacitor charged through a rectifier, and maintained charged to a reference voltage level by a transistor switch and voltage comparator. A thyristor is triggered to discharge the storage capacitor through a saturable reactor and fractional turn saturable transformer having a secondary to primary turn ratio N of n:l/n = n[sup 2]. The saturable reactor functions as a soaker'' while the thyristor reaches saturation, and then switches to a low impedance state. The saturable transformer functions as a switching transformer with high impedance while a load coupling capacitor charges, and then switches to a low impedance state to dump the charge of the storage capacitor into the load through the coupling capacitor. The transformer is comprised of a multilayer core having two secondary windings tightly wound and connected in parallel to add their output voltage and reduce output inductance, and a number of single turn windings connected in parallel at nodes for the primary winding, each single turn winding linking a different one of the layers of the multilayer core. The load may be comprised of a resistive beampipe for a linear particle accelerator and capacitance of a pulse forming network. To hold off discharge of the capacitance until it is fully charged, a saturable core is provided around the resistive beampipe to isolate the beampipe from the capacitance until it is fully charged. 5 figs.

  11. Nanoscale memristive radiofrequency switches.

    PubMed

    Pi, Shuang; Ghadiri-Sadrabadi, Mohammad; Bardin, Joseph C; Xia, Qiangfei

    2015-01-01

    Radiofrequency switches are critical components in wireless communication systems and consumer electronics. Emerging devices include switches based on microelectromechanical systems and phase-change materials. However, these devices suffer from disadvantages such as large physical dimensions and high actuation voltages. Here we propose and demonstrate a nanoscale radiofrequency switch based on a memristive device. The device can be programmed with a voltage as low as 0.4 V and has an ON/OFF conductance ratio up to 10(12) with long state retention. We measure the radiofrequency performance of the switch up to 110 GHz and demonstrate low insertion loss (0.3 dB at 40 GHz), high isolation (30 dB at 40 GHz), an average cutoff frequency of 35 THz and competitive linearity and power-handling capability. Our results suggest that, in addition to their application in memory and computing, memristive devices are also a leading contender for radiofrequency switch applications. PMID:26108890

  12. Atomic Scale Plasmonic Switch.

    PubMed

    Emboras, Alexandros; Niegemann, Jens; Ma, Ping; Haffner, Christian; Pedersen, Andreas; Luisier, Mathieu; Hafner, Christian; Schimmel, Thomas; Leuthold, Juerg

    2016-01-13

    The atom sets an ultimate scaling limit to Moore's law in the electronics industry. While electronics research already explores atomic scales devices, photonics research still deals with devices at the micrometer scale. Here we demonstrate that photonic scaling, similar to electronics, is only limited by the atom. More precisely, we introduce an electrically controlled plasmonic switch operating at the atomic scale. The switch allows for fast and reproducible switching by means of the relocation of an individual or, at most, a few atoms in a plasmonic cavity. Depending on the location of the atom either of two distinct plasmonic cavity resonance states are supported. Experimental results show reversible digital optical switching with an extinction ratio of 9.2 dB and operation at room temperature up to MHz with femtojoule (fJ) power consumption for a single switch operation. This demonstration of an integrated quantum device allowing to control photons at the atomic level opens intriguing perspectives for a fully integrated and highly scalable chip platform, a platform where optics, electronics, and memory may be controlled at the single-atom level.

  13. Multiple switch actuator

    DOEpatents

    Beyer, Edward T.

    1976-01-06

    The present invention relates to switches and switch actuating devices to be operated for purposes of arming a bomb or other missile as it is dropped or released from an aircraft. The particular bomb or missile in which this invention is applied is one in which there is a plurality of circuits which are to be armed by the closing of switches upon dropping or releasing of the bomb. The operation of the switches to closed position is normally accomplished by means of a pull-out wire; that is, a wire which is withdrawn from the bomb or missile at the time of release of the bomb, one end of the wire being attached to the aircraft. The conditions to be met are that the arming switches must be positively and surely maintained in open position until the bomb is released and the arming action is effected. The action of the pull-out wire in achieving the arming action must be sure and positive with minimum danger of malfunctioning, jamming or binding.

  14. Input Power Quality Improvement in Switched Reluctance Motor Drive using Minnesota Rectifier

    NASA Astrophysics Data System (ADS)

    Singh, B.; Rajesh, M.

    2013-09-01

    This paper deals with an input power quality improvement in a midpoint converter based switched reluctance motor (SRM) drive at ac mains using Minnesota rectifier. Normally a midpoint converter is used as a power converter for SRM drive. Conventionally three phase ac mains fed bridge rectifier is used as a dc source to feed this power converter which produces high content of harmonics at ac mains with a very low power factor. The proposed Minnesota rectifier with a midpoint converter fed SRM drive improves the power factor at ac mains with low current harmonics. This method provides constant dc link voltage and balanced capacitor voltages of the midpoint converter. The Minnesota rectifier fed SRM drive is modelled and its performance is simulated in Matlab/Simulink environment. The performance of Minnesota rectifier is compared with a conventional bridge topology for SRM drive to demonstrate improved power quality at ac mains.

  15. Microfabricated triggered vacuum switch

    DOEpatents

    Roesler, Alexander W.; Schare, Joshua M.; Bunch, Kyle

    2010-05-11

    A microfabricated vacuum switch is disclosed which includes a substrate upon which an anode, cathode and trigger electrode are located. A cover is sealed over the substrate under vacuum to complete the vacuum switch. In some embodiments of the present invention, a metal cover can be used in place of the trigger electrode on the substrate. Materials used for the vacuum switch are compatible with high vacuum, relatively high temperature processing. These materials include molybdenum, niobium, copper, tungsten, aluminum and alloys thereof for the anode and cathode. Carbon in the form of graphitic carbon, a diamond-like material, or carbon nanotubes can be used in the trigger electrode. Channels can be optionally formed in the substrate to mitigate against surface breakdown.

  16. Switching power supply

    DOEpatents

    Mihalka, A.M.

    1984-06-05

    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.

  17. Optical computer switching network

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    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.

  18. FAST ACTING CURRENT SWITCH

    DOEpatents

    Batzer, T.H.; Cummings, D.B.; Ryan, J.F.

    1962-05-22

    A high-current, fast-acting switch is designed for utilization as a crowbar switch in a high-current circuit such as used to generate the magnetic confinement field of a plasma-confining and heat device, e.g., Pyrotron. The device particularly comprises a cylindrical housing containing two stationary, cylindrical contacts between which a movable contact is bridged to close the switch. The movable contact is actuated by a differential-pressure, airdriven piston assembly also within the housing. To absorb the acceleration (and the shock imparted to the device by the rapidly driven, movable contact), an adjustable air buffer assembly is provided, integrally connected to the movable contact and piston assembly. Various safety locks and circuit-synchronizing means are also provided to permit proper cooperation of the invention and the high-current circuit in which it is installed. (AEC)

  19. SWITCH user's manual

    NASA Technical Reports Server (NTRS)

    1987-01-01

    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.

  20. Trapping polar molecules in an ac trap

    SciTech Connect

    Bethlem, Hendrick L.; Veldhoven, Jacqueline van; Schnell, Melanie; Meijer, Gerard

    2006-12-15

    Polar molecules in high-field seeking states cannot be trapped in static traps as Maxwell's equations do not allow a maximum of the electric field in free space. It is possible to generate an electric field that has a saddle point by superposing an inhomogeneous electric field to an homogeneous electric field. In such a field, molecules are focused along one direction, while being defocused along the other. By reversing the direction of the inhomogeneous electric field the focusing and defocusing directions are reversed. When the fields are being switched back and forth at the appropriate rate, this leads to a net focusing force in all directions. We describe possible electrode geometries for creating the desired fields and discuss their merits. Trapping of {sup 15}ND{sub 3} ammonia molecules in a cylindrically symmetric ac trap is demonstrated. We present measurements of the spatial distribution of the trapped cloud as a function of the settings of the trap and compare these to both a simple model assuming a linear force and to full three-dimensional simulations of the experiment. With the optimal settings, molecules within a phase-space volume of 270 mm{sup 3} (m/s){sup 3} remain trapped. This corresponds to a trap depth of about 5 mK and a trap volume of about 20 mm{sup 3}.

  1. Thermionic gas switch

    DOEpatents

    Hatch, George L.; Brummond, William A.; Barrus, Donald M.

    1986-01-01

    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.

  2. Input current shaped ac-to-dc converters

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Input current shaping techniques for ac-to-dc converters were investigated. Input frequencies much higher than normal, up to 20 kHz were emphasized. Several methods of shaping the input current waveform in ac-to-dc converters were reviewed. The simplest method is the LC filter following the rectifier. The next simplest method is the resistor emulation approach in which the inductor size is determined by the converter switching frequency and not by the line input frequency. Other methods require complicated switch drive algorithms to construct the input current waveshape. For a high-frequency line input, on the order of 20 kHz, the simple LC cannot be discarded so peremptorily, since the inductor size can be compared with that for the resistor emulation method. In fact, since a dc regulator will normally be required after the filter anyway, the total component count is almost the same as for the resistor emulation method, in which the filter is effectively incorporated into the regulator.

  3. 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

  4. 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

  5. 43. OBLIQUE VIEW, GREEN SWITCH TOWER, COS COB, SHOWING SWITCH ...

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

    43. OBLIQUE 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

  6. 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

  7. 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

  8. Chemical dampening of Ly6C(hi) monocytes in the periphery produces anti-depressant effects in mice.

    PubMed

    Zheng, Xiao; Ma, Sijing; Kang, An; Wu, Mengqiu; Wang, Lin; Wang, Qiong; Wang, Guangji; Hao, Haiping

    2016-01-19

    The involvement of systemic immunity in depression pathogenesis promises a periphery-targeting paradigm in novel anti-depressant discovery. However, relatively little is known about druggable targets in the periphery for mental and behavioral control. Here we report that targeting Ly6C(hi) monocytes in blood can serve as a strategy for anti-depressant purpose. A natural compound, ginsenoside Rg1 (Rg1), was firstly validated as a periphery-restricted chemical probe. Rg1 selectively suppressed Ly6C(hi) monocytes recruitment to the inflamed mice brain. The proinflammatory potential of Ly6C(hi) monocytes to activate astrocytes was abrogated by Rg1, which led to a blunted feedback release of CCL2 to recruit the peripheral monocytes. In vitro study demonstrated that Rg1 pretreatment on activated THP-1 monocytes retarded their ability to trigger CCL2 secretion from co-cultured U251 MG astrocytes. CCL2-triggered p38/MAPK and PI3K/Akt activation were involved in the action of Rg1. Importantly, in mice models, we found that dampening Ly6C(hi) monocytes at the periphery ameliorated depression-like behavior induced by neuroinflammation or chronic social defeat stress. Together, our work unravels that blood Ly6C(hi) monocytes may serve as the target to enable remote intervention on the depressed brain, and identifies Rg1 as a lead compound for designing drugs targeting peripheral CCL2 signals.

  9. Capitalism Reborn, Chaos and the Post-Socialist Freefall: A View from Europe's "New Periphery"

    ERIC Educational Resources Information Center

    Templer, Bill

    2014-01-01

    The present paper--from a vantage in Bulgaria, and focusing in significant part on this country as an iconic example of the "post-socialist freefall' and its dystopia on European capitalism's neocolonial "new periphery"--is a revised version of an earlier chapter in "Immiseration Capitalism and Education: Austerity,…

  10. US Study Abroad from the Periphery to the Center of the Global Curriculum in the Information Age

    ERIC Educational Resources Information Center

    Mukherjee, Mousumi

    2012-01-01

    The Higher Education Act of 1965 for the first time gave discretionary authority to campuses to use federal financial aid in support of students studying abroad. Thereafter, US study abroad has thus evolved from the periphery to the center of the global curriculum. In 2005 the Lincoln Commission report proposed an ambitious goal of sending one…

  11. Muslim oil and gas periphery; the future of hydrocarbons in Africa, southeast Asia and the Caspian. Master`s thesis

    SciTech Connect

    Crockett, B.D.

    1997-12-01

    This thesis is a study of the contemporary political, economic, and technical developments and future prospects of the Muslim hydrocarbon exporters of Africa, Southeast Asia, and the Caspian. The established Muslim oil and gas periphery of Africa and Southeast Asia has four members in the Organization of Petroleum Exporting Countries (OPEC) and is systemically increasing its production of natural gas. I analyze US government and corporate policies regarding the countries and the major dilemmas of the Muslim hydrocarbon periphery. The first chapter provides a selective overview of global energy source statistics; the policies, disposition and composition of the major hydrocarbon production and consumption players and communities; a selective background of OPEC and its impact on the globe; and a general portrait of how the Muslim periphery piece fits into the overall Muslim oil and gas puzzle. Chapter two analyzes the established Muslim oil and gas periphery of Africa and Southeast Asia asking the following questions: What are the major political, economic, and technical trends and dilemmas affecting these producer nations. And what are the United States` policies and relationships with these producers. Chapter three asks the same questions as chapter two, but with regard to the newly independent states of the Caspian Sea. I probe the regional petroleum exploration and transportation dilemmas in some detail.

  12. Whoever Doesn't HOP Must Be Superior: The Russian Left-Periphery and the Emergence of Superiority

    ERIC Educational Resources Information Center

    Scott, Tatiana V.

    2012-01-01

    This dissertation maps the left-periphery of the Russian language, presenting a new geometry of Russian main and subordinate clauses in order to account for a number of phenomena: single and multiple wh-constructions, sluicing constructions, and coordinate multiple wh-constructions (CMW), as well as to predict various occurring word-orders.…

  13. Chemical dampening of Ly6Chi monocytes in the periphery produces anti-depressant effects in mice

    PubMed Central

    Zheng, Xiao; Ma, Sijing; Kang, An; Wu, Mengqiu; Wang, Lin; Wang, Qiong; Wang, Guangji; Hao, Haiping

    2016-01-01

    The involvement of systemic immunity in depression pathogenesis promises a periphery-targeting paradigm in novel anti-depressant discovery. However, relatively little is known about druggable targets in the periphery for mental and behavioral control. Here we report that targeting Ly6Chi monocytes in blood can serve as a strategy for anti-depressant purpose. A natural compound, ginsenoside Rg1 (Rg1), was firstly validated as a periphery-restricted chemical probe. Rg1 selectively suppressed Ly6Chi monocytes recruitment to the inflamed mice brain. The proinflammatory potential of Ly6Chi monocytes to activate astrocytes was abrogated by Rg1, which led to a blunted feedback release of CCL2 to recruit the peripheral monocytes. In vitro study demonstrated that Rg1 pretreatment on activated THP-1 monocytes retarded their ability to trigger CCL2 secretion from co-cultured U251 MG astrocytes. CCL2-triggered p38/MAPK and PI3K/Akt activation were involved in the action of Rg1. Importantly, in mice models, we found that dampening Ly6Chi monocytes at the periphery ameliorated depression-like behavior induced by neuroinflammation or chronic social defeat stress. Together, our work unravels that blood Ly6Chi monocytes may serve as the target to enable remote intervention on the depressed brain, and identifies Rg1 as a lead compound for designing drugs targeting peripheral CCL2 signals. PMID:26783261

  14. Gigantic low-gradient landslides in the northern periphery of the Crimean Mountains (Ukraine)

    NASA Astrophysics Data System (ADS)

    Pánek, Tomáš; Hradecký, Jan; Smolková, Veronika; Šilhán, Karel

    2008-03-01

    Large-scale, low-gradient ancient landslides estimated at 5.4-18.9 km 2 in area and ˜ 0.2-1.2 km 3 in volume have been studied in the northern hilly periphery of the Crimean Mountains (Ukraine). They originated on slopes along wide water gaps of rivers (Belbek, Kacha, Alma and Biyuk-Karasu) crossing the cuestas of the northern foothills. The slopes generally consist of slightly northward tilting Miocene (mainly Sarmatian) limestones overlying weak, clay-rich Lower Neogene-Palaeogene substratum with a significant content of smectite. Although the region is characterised by the least active contemporary morphodynamics within the Crimean Mountains, the landslides which were studied are of the same size or even larger than various types of landslides occupying active geomorphic domains of the highest mountain range in the southernmost part of the peninsula. The landslides are generally a spreading type, but the sliding mechanics were probably very complex, involving toppling, rotational slides, gravitational folding and translational block slides. All the landslides which were studied are located in the vicinity of regional faults and three of them have headscarps aligned along faults. A common feature is also a location close (within several km) to the Mesozoic suture zone which is the most important tectonic feature in the northern periphery of the Crimean Orogene. This suture was formerly classified as aseismic; however, evidence of strong, low-frequency palaeoearthquakes was collected during the last decade within both the Mesozoic suture and the low-lying northern part of the Crimean Peninsula. Radiocarbon dating of deposits associated with the landslides has revealed at least two phases of increased landslide-activity during the Late Glacial chronozone and Holocene epoch. The main landslide phase presumably took place at some time between the Late Glacial and Atlantic chronozones. Minor reactivation of landslide toes occurred during the Subatlantic chronozone

  15. Evaluating the Rationale for the Utility-Accessible External Disconnect Switch: Preprint

    SciTech Connect

    Coddington, M. H.

    2008-05-01

    This paper describes the utility-accessible alternating current (AC) external disconnect switch (EDS) for distributed generators, including photovoltaic (PV) systems, which is a hardware feature that allows a utility's employees to manually disconnect a customer-owned generator from the electricity grid.

  16. A Switching-Mode Power Supply Design Tool to Improve Learning in a Power Electronics Course

    ERIC Educational Resources Information Center

    Miaja, P. F.; Lamar, D. G.; de Azpeitia, M.; Rodriguez, A.; Rodriguez, M.; Hernando, M. M.

    2011-01-01

    The static design of ac/dc and dc/dc switching-mode power supplies (SMPS) relies on a simple but repetitive process. Although specific spreadsheets, available in various computer-aided design (CAD) programs, are widely used, they are difficult to use in educational applications. In this paper, a graphic tool programmed in MATLAB is presented,…

  17. Capillary micro-switches

    NASA Astrophysics Data System (ADS)

    Steen, Paul; Matalanis, Claude; Hirsa, Amir; Cox, Christhopher

    2002-11-01

    A capillary surface is a liquid/liquid or liquid/gas interface whose shape is determined by surface tension. Capillary surfaces occur when the capillary length is large compared to the container scale, as happens for typical liquids against gas on the sub-millimeter scale on Earth and on the meter scale in the micro-gravity environment of space vehicles. Manipulating capillary surfaces has emerged as a leading strategy for moving liquids on the micro-scale [1]. Practitioners have yet to take advantage of capillary instability in their design of devices, though. We illustrate how the response diagram of a single switch (bi-stable device) can be constructed from that of two capillary elements, how that of a system of switches (a pair) can be built from that of a single switch and finally how understanding the response of the system guides us to observations of new behavior in the laboratory. Experiments on capillary surfaces use either a soap-film analog (10 centimeter scale) or a liquid/gas (millimeter scale) apparatus. Progress is reported on the application of an array of micro-switches to make a controllable adhesion device, with the aim of effecting droplet transport. 1. Cho, Fan, Moon and Kim, "Towards digital microfluidic circuits: creating, transporting, cutting and merging liquid droplets by electrowetting-based actuation." Proc. 15th IEEE Int'l Conf. on MEMS, January 2002.

  18. Photonic MEMS switch applications

    NASA Astrophysics Data System (ADS)

    Husain, Anis

    2001-07-01

    As carriers and service providers continue their quest for profitable network solutions, they have shifted their focus from raw bandwidth to rapid provisioning, delivery and management of revenue generating services. Inherently transparent to data rate the transmission wavelength and data format, MEMS add scalability, reliability, low power and compact size providing flexible solutions to the management and/or fiber channels in long haul, metro, and access networks. MEMS based photonic switches have gone from the lab to commercial availability and are now currently in carrier trials and volume production. 2D MEMS switches offer low up-front deployment costs while remaining scalable to large arrays. They allow for transparent, native protocol transmission. 2D switches enable rapid service turn-up and management for many existing and emerging revenue rich services such as storage connectivity, optical Ethernet, wavelength leasing and optical VPN. As the network services evolve, the larger 3D MEMS switches, which provide greater scalability and flexibility, will become economically viable to serve the ever-increasing needs.

  19. Gas injected vacuum switch

    DOEpatents

    Hardin, K. Dan

    1977-01-01

    The disclosure relates to a gas injected vacuum switch comprising a housing having an interior chamber, a conduit for evacuating the interior chamber, within the chamber an anode and a cathode spaced from the anode, and a detonator for injecting electrically conductive gas into the chamber between the anode and the cathode to provide a current path therebetween.

  20. Kiowa Creek Switching Station

    SciTech Connect

    Not Available

    1990-03-01

    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.

  1. Multipath star switch controller

    NASA Technical Reports Server (NTRS)

    Anderson, T. O.

    1980-01-01

    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.

  2. Nanoelectromechanical digital logic circuits using curved cantilever switches with amorphous-carbon-coated contacts

    NASA Astrophysics Data System (ADS)

    Ayala, Christopher L.; Grogg, Daniel; Bazigos, Antonios; Bleiker, Simon J.; Fernandez-Bolaños, Montserrat; Niklaus, Frank; Hagleitner, Christoph

    2015-11-01

    Nanoelectromechanical (NEM) switches have the potential to complement or replace traditional CMOS transistors in the area of ultra-low-power digital electronics. This paper reports the demonstration of prototype circuits including the first 3-stage ring oscillator built using cell-level digital logic elements based on curved NEM switches. The ring oscillator core occupies an area of 30 μm × 10 μm using 6 NEM switches. Each NEM switch device has a footprint of 5 μm × 3 μm, an air gap of 60 μm and is coated with amorphous carbon (a-C) for reliable operation. The ring oscillator operates at a frequency of 6.7 MHz, and confirms the simulated inverter propagation delay of 25 ns. The successful fabrication and measurement of this demonstrator are key milestones on the way towards an optimized, scaled technology with sub-nanosecond switching times, lower operating voltages and VLSI implementation.

  3. Closing photoconductive semiconductor switches

    SciTech Connect

    Loubriel, G.M.; Zutavern, F.J.; Hjalmarson, H.P.; O'Malley, M.W.

    1989-01-01

    One of the most important limitations of Photoconductive Semiconductor Switches (PCSS) for pulsed power applications is the high laser powers required to activate the switches. In this paper, we discuss recent developments on two different aspects of GaAs PCSS that result in reductions in laser power by a factor of nearly 1000. The advantages of using GaAs over Si are many. First of all, the resistivity of GaAs can be orders of magnitude higher than that of the highest resistivity Si material, thus allowing GaAs switches to withstand dc voltages without thermal runaway. Secondly, GaAs has a higher carrier mobility than Si and, thus, is more efficient (per carrier). Finally, GaAs switches can have naturally fast (ns) opening times at room temperature and low fields, microsecond opening times at liquid nitrogen temperature of 77 K, or, on demand, closing and opening at high fields and room temperature by a mechanism called lock-on (see Ref. 1). By contrast, Si switches typically opening times of milliseconds. The amount of laser light required to trigger GaAs for lock-on, or at 77 K, is about three orders of magnitude lower than at room temperature. In this paper we describe the study of lock-on in GaAs and InP, as well as switching of GaAs at 77 K. We shall show that when GaAs is switched at 77 K, the carrier lifetime is about three orders of magnitude longer than it is at room temperature. We shall explain the change in lifetime in terms of the change in electron capture cross section of the deep levels in GaAs (these are defect or impurity levels in the band gap). In the second section, we describe the lock-on effect, now seen in GaAs and InP, and at fields as high as 70 kV/cm. We show how lock-on can be tailored by changing the GaAs temperature or by neutron bombardment. In the third section, we discuss possible lock-on mechanisms. 5 refs., 5 figs.

  4. Heat-transfer thermal switch

    NASA Technical Reports Server (NTRS)

    Friedell, M. V.; Anderson, A. J.

    1974-01-01

    Thermal switch maintains temperature of planetary lander, within definite range, by transferring heat. Switch produces relatively large stroke and force, uses minimum electrical power, is lightweight, is vapor pressure actuated, and withstands sterilization temperatures without damage.

  5. Switching power pulse system

    DOEpatents

    Aaland, Kristian

    1983-01-01

    A switching system for delivering pulses of power from a source (10) to a load (20) using a storage capacitor (C3) charged through a rectifier (D1, D2), and maintained charged to a reference voltage level by a transistor switch (Q1) and voltage comparator (12). A thyristor (22) is triggered to discharge the storage capacitor through a saturable reactor (18) and fractional turn saturable transformer (16) having a secondary to primary turn ratio N of n:l/n=n.sup.2. The saturable reactor (18) functions as a "soaker" while the thyristor reaches saturation, and then switches to a low impedance state. The saturable transformer functions as a switching transformer with high impedance while a load coupling capacitor (C4) charges, and then switches to a low impedance state to dump the charge of the storage capacitor (C3) into the load through the coupling capacitor (C4). The transformer is comprised of a multilayer core (26) having two secondary windings (28, 30) tightly wound and connected in parallel to add their output voltage and reduce output inductance, and a number of single turn windings connected in parallel at nodes (32, 34) for the primary winding, each single turn winding linking a different one of the layers of the multilayer core. The load may be comprised of a resistive beampipe (40) for a linear particle accelerator and capacitance of a pulse forming network (42). To hold off discharge of the capacitance until it is fully charged, a saturable core (44) is provided around the resistive beampipe (40) to isolate the beampipe from the capacitance (42) until it is fully charged.

  6. Transparent electrode for optical switch

    DOEpatents

    Goldhar, J.; Henesian, M.A.

    1984-10-19

    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.

  7. Radiation sensitive solid state switch

    NASA Technical Reports Server (NTRS)

    Hutto, R. J. (Inventor)

    1973-01-01

    A mechanically operable solid state switch suited for use in achieving a variable circuit-switching function is described. This switch is characterized by an annular array of photoresponsive switching devices, disposed in communication with an included source of radiation, and a plurality of interchangeable, mechanically operable interrupter disks. Each disk has a predetermined pattern of transparent and opaque portions. Operative displacement of each disk serves to make and break selected electrical circuits through the photo responsive devices of said array.

  8. The 'rural pipeline' and retention of rural health professionals in Europe's northern peripheries.

    PubMed

    Carson, Dean B; Schoo, Adrian; Berggren, Peter

    2015-12-01

    The major advance in informing rural workforce policy internationally over the past 25 years has been the recognition of the importance of the 'rural pipeline'. The rural pipeline suggests that people with 'rural origin' (who spent some childhood years in rural areas) and/or 'rural exposure' (who do part of their professional training in rural areas) are more likely to select rural work locations. What is not known is whether the rural pipeline also increases the length of time professionals spend in rural practice throughout their careers. This paper analyses data from a survey of rural health professionals in six countries in the northern periphery of Europe in 2013 to examine the relationship between rural origin and rural exposure and the intention to remain in the current rural job or to preference rural jobs in future. Results are compared between countries, between different types of rural areas (based on accessibility to urban centres), different occupations and workers at different stages of their careers. The research concludes that overall the pipeline does impact on retention, and that both rural origin and rural exposure make a contribution. However, the relationship is not strong in all contexts, and health workforce policy should recognise that retention may in some cases be improved by recruiting beyond the pipeline.

  9. [Throat disease in the periphery of Europe: the introduction of diphteria antitoxin in Romsdal county].

    PubMed

    Breivik, Edvard; Gradmann, Christoph

    2014-04-01

    Diphteria played a key role in establishing the bacteriological model for explaining infectious disease. This understanding of bacteriological factors spurred research that culminated in the development of diphteria antitoxin, the first effective therapeutic cure for an epidemiological disease. Prior to the introduction of antitoxin, isolation and disinfection were regarded as the key defences against diphteria. The opportunity to combine antitoxin therapy with existing methods for combatting the disease was a key factor for the rapid spread of the antitoxin. Diphteria antitoxin was first used in Romsdal county in 1895. Initially the serum had to be ordered from manufacturers abroad, which restricted its application in the district. Few available doctors and long transport routes were reasons that prevented the antitoxin from reaching its full potential. Industrial manufacturing methods were an obstacle to serum production in peripheral areas. In Norway, production of serum gradually got underway in Kristiania, which was one factor that caused mortality from diphteria to decline faster there than in other parts of the country. In this article we will elucidate the relationship between the centre and the periphery in the spread of medical advances by studying the implementation of diphteria antitoxin in Romsdal county. PMID:24721865

  10. The 'rural pipeline' and retention of rural health professionals in Europe's northern peripheries.

    PubMed

    Carson, Dean B; Schoo, Adrian; Berggren, Peter

    2015-12-01

    The major advance in informing rural workforce policy internationally over the past 25 years has been the recognition of the importance of the 'rural pipeline'. The rural pipeline suggests that people with 'rural origin' (who spent some childhood years in rural areas) and/or 'rural exposure' (who do part of their professional training in rural areas) are more likely to select rural work locations. What is not known is whether the rural pipeline also increases the length of time professionals spend in rural practice throughout their careers. This paper analyses data from a survey of rural health professionals in six countries in the northern periphery of Europe in 2013 to examine the relationship between rural origin and rural exposure and the intention to remain in the current rural job or to preference rural jobs in future. Results are compared between countries, between different types of rural areas (based on accessibility to urban centres), different occupations and workers at different stages of their careers. The research concludes that overall the pipeline does impact on retention, and that both rural origin and rural exposure make a contribution. However, the relationship is not strong in all contexts, and health workforce policy should recognise that retention may in some cases be improved by recruiting beyond the pipeline. PMID:26321193

  11. Precise localization of metal nanoparticles in dendrimer nanosnakes or inner periphery and consequences in catalysis

    PubMed Central

    Liu, Xiang; Gregurec, Danijela; Irigoyen, Joseba; Martinez, Angel; Moya, Sergio; Ciganda, Roberto; Hermange, Philippe; Ruiz, Jaime; Astruc, Didier

    2016-01-01

    Understanding the relationship between the location of nanoparticles (NPs) in an organic matrix and their catalytic performances is essential for catalyst design. Here we show that catalytic activities of Au, Ag and CuNPs stabilized by dendrimers using coordination to intradendritic triazoles, galvanic replacement or stabilization outside dendrimers strongly depends on their location. AgNPs are found at the inner click dendrimer periphery, whereas CuNPs and AuNPs are encapsulated in click dendrimer nanosnakes. AuNPs and AgNPs formed by galvanic replacement are larger than precursors and only partly encapsulated. AuNPs are all the better 4-nitrophenol reduction catalysts as they are less sterically inhibited by the dendrimer interior, whereas on the contrary CuNPs are all the better alkyne azide cycloaddition catalysts as they are better protected from aerobic oxidation inside dendrimers. This work highlights the role of the location in macromolecules on the catalytic efficiency of metal nanoparticles and rationalizes optimization in catalyst engineering. PMID:27759006

  12. Lethal Thermal Impact at Periphery of Pyroclastic Surges: Evidences at Pompeii

    PubMed Central

    Mastrolorenzo, Giuseppe; Petrone, Pierpaolo; Pappalardo, Lucia; Guarino, Fabio M.

    2010-01-01

    Background The evaluation of mortality of pyroclastic surges and flows (PDCs) produced by explosive eruptions is a major goal in risk assessment and mitigation, particularly in distal reaches of flows that are often heavily urbanized. Pompeii and the nearby archaeological sites preserve the most complete set of evidence of the 79 AD catastrophic eruption recording its effects on structures and people. Methodology/Principal Findings Here we investigate the causes of mortality in PDCs at Pompeii and surroundings on the bases of a multidisciplinary volcanological and bio-anthropological study. Field and laboratory study of the eruption products and victims merged with numerical simulations and experiments indicate that heat was the main cause of death of people, heretofore supposed to have died by ash suffocation. Our results show that exposure to at least 250°C hot surges at a distance of 10 kilometres from the vent was sufficient to cause instant death, even if people were sheltered within buildings. Despite the fact that impact force and exposure time to dusty gas declined toward PDCs periphery up to the survival conditions, lethal temperatures were maintained up to the PDCs extreme depositional limits. Conclusions/Significance This evidence indicates that the risk in flow marginal zones could be underestimated by simply assuming that very thin distal deposits, resulting from PDCs with poor total particle load, correspond to negligible effects. Therefore our findings are essential for hazard plans development and for actions aimed to risk mitigation at Vesuvius and other explosive volcanoes. PMID:20559555

  13. Sulfur-annulated hexa-peri-hexabenzocoronene decorated with phenylthio groups at the periphery.

    PubMed

    Tan, Yuan-Zhi; Osella, Silvio; Liu, Yi; Yang, Bo; Beljonne, David; Feng, Xinliang; Müllen, Klaus

    2015-03-01

    The chemical nature of the edge periphery essentially determines the physical properties of graphene. As a molecular-level model system, large polycyclic aromatic hydrocarbons, that is, so-called nanographenes, can be chemically modified through either edge functionalization or doping with heteroatoms. Although the synthetic methods for edge substitution are well-developed, incorporation with heteroatoms by the bay annulation of large PAHs remains an enormous challenge. In this study, we present a feasible peripheral sulfur annulation of hexa-peri-hexabenzocoronene (HBC) by thiolation of perchlorinated HBC. The tri-sulfur-annulated HBC and di-sulfur-annulated HBC decorated with phenylthio groups were obtained and characterized by X-ray diffraction, revealing their distinct sulfur-annulated peripheral structure. Associated with theoretical calculations, we propose that the regioselective sulfur annulation results from the minimization of strain in the aromatic backbone. We further demonstrate the structure-correlated property modulation by sulfur annulation, manifested by a decrease in band gap and tunable redox activity.

  14. The Circadian System: A Regulatory Feedback Network of Periphery and Brain.

    PubMed

    Buijs, Frederik N; León-Mercado, Luis; Guzmán-Ruiz, Mara; Guerrero-Vargas, Natali N; Romo-Nava, Francisco; Buijs, Ruud M

    2016-05-01

    Circadian rhythms are generated by the autonomous circadian clock, the suprachiasmatic nucleus (SCN), and clock genes that are present in all tissues. The SCN times these peripheral clocks, as well as behavioral and physiological processes. Recent studies show that frequent violations of conditions set by our biological clock, such as shift work, jet lag, sleep deprivation, or simply eating at the wrong time of the day, may have deleterious effects on health. This infringement, also known as circadian desynchronization, is associated with chronic diseases like diabetes, hypertension, cancer, and psychiatric disorders. In this review, we will evaluate evidence that these diseases stem from the need of the SCN for peripheral feedback to fine-tune its output and adjust physiological processes to the requirements of the moment. This feedback can vary from neuronal or hormonal signals from the liver to changes in blood pressure. Desynchronization renders the circadian network dysfunctional, resulting in a breakdown of many functions driven by the SCN, disrupting core clock rhythms in the periphery and disorganizing cellular processes that are normally driven by the synchrony between behavior and peripheral signals with neuronal and humoral output of the hypothalamus. Consequently, we propose that the loss of synchrony between the different elements of this circadian network as may occur during shiftwork and jet lag is the reason for the occurrence of health problems. PMID:27053731

  15. The impact of fiscal austerity on suicide mortality: Evidence across the 'Eurozone periphery'.

    PubMed

    Antonakakis, Nikolaos; Collins, Alan

    2015-11-01

    While linkages between some macroeconomic phenomena and suicides in some countries have been explored, only two studies, hitherto, have established a causal relationship between fiscal austerity and suicide, albeit in a single country. The aim of this study is to provide the first systematic multiple-country evidence of a causal relationship of fiscal austerity on time-, gender-, and age-specific suicide mortality across five Eurozone peripheral countries, namely Greece, Ireland, Italy, Portugal and Spain over the period 1968-2012, while controlling for various socioeconomic differences. The impact of fiscal adjustments is found to be gender-, age- and time-specific. Specifically, fiscal austerity has short-, medium- and long-run suicide increasing effects on the male population in the 65-89 age group. A 1% reduction in government spending is associated with a 1.38%, 2.42% and 3.32% increase in the short-, medium- and long-run, respectively, of male suicides rates in the 65-89 age group in the Eurozone periphery. These results are highly robust to alternative measures of fiscal austerity. Improved labour market institutions help mitigate the negative effects of fiscal austerity on suicide mortality. PMID:26458118

  16. Arf-like GTPase Arl8: Moving from the periphery to the center of lysosomal biology

    PubMed Central

    Khatter, Divya; Sindhwani, Aastha; Sharma, Mahak

    2015-01-01

    Lysosomes are dynamic organelles that not only mediate degradation of cellular substrates but also play critical roles in processes such as cholesterol homeostasis, plasma membrane repair, antigen presentation, and cell migration. The small GTPase Arl8, a member of Arf-like (Arl) family of proteins, has recently emerged as a crucial regulator of lysosome positioning and membrane trafficking toward lysosomes. Through interaction with its effector SKIP, the human Arl8 paralog (Arl8b) mediates kinesin-1 dependent motility of lysosomes on microtubule tracks toward the cell periphery. Arl8b-mediated kinesin-driven motility is also implicated in regulating lytic granule polarization in NK cells, lysosome tubulation in macrophages, cell spreading, and migration. Moreover, Arl8b regulates membrane traffic toward lysosomes by recruiting subunits of the HOPS complex, a multi-subunit tethering complex that mediates endo-lysosome fusion. Here we provide a brief review on this recently characterized lysosomal GTPase and summarize the studies focusing on its known functions in regulating lysosomal motility and delivery of endocytic cargo to the lysosomes. We also explore the role of human Arl8b and its orthologs upon infection by intracellular pathogens. PMID:27057420

  17. Simulated masking of right whale sounds by shipping noise: incorporating a model of the auditory periphery.

    PubMed

    Cunningham, Kane A; Mountain, David C

    2014-03-01

    Many species of large, mysticete whales are known to produce low-frequency communication sounds. These low-frequency sounds are susceptible to communication masking by shipping noise, which also tends to be low frequency in nature. The size of these species makes behavioral assessment of auditory capabilities in controlled, captive environments nearly impossible, and field-based playback experiments are expensive and necessarily limited in scope. Hence, it is desirable to produce a masking model for these species that can aid in determining the potential effects of shipping and other anthropogenic noises on these protected animals. The aim of this study was to build a model that combines a sophisticated representation of the auditory periphery with a spectrogram-based decision stage to predict masking levels. The output of this model can then be combined with a habitat-appropriate propagation model to calculate the potential effects of noise on communication range. For this study, the model was tested on three common North Atlantic right whale communication sounds, both to demonstrate the method and to probe how shipping noise affects the detection of sounds with varying spectral and temporal characteristics.

  18. Perceptual learning reduces crowding in amblyopia and in the normal periphery.

    PubMed

    Hussain, Zahra; Webb, Ben S; Astle, Andrew T; McGraw, Paul V

    2012-01-11

    Amblyopia is a developmental visual disorder of cortical origin, characterized by crowding and poor acuity in central vision of the affected eye. Crowding refers to the adverse effects of surrounding items on object identification, common only in normal peripheral but not central vision. We trained a group of adult human amblyopes on a crowded letter identification task to assess whether the crowding problem can be ameliorated. Letter size was fixed well above the acuity limit, and letter spacing was varied to obtain spacing thresholds for central target identification. Normally sighted observers practiced the same task in their lower peripheral visual field. Independent measures of acuity were taken in flanked and unflanked conditions before and after training to measure crowding ratios at three fixed letter separations. Practice improved the letter spacing thresholds of both groups on the training task, and crowding ratios were reduced after posttest. The reductions in crowding in amblyopes were associated with improvements in standard measures of visual acuity. Thus, perceptual learning reduced the deleterious effects of crowding in amblyopia and in the normal periphery. The results support the effectiveness of plasticity-based approaches for improving vision in adult amblyopes and suggest experience-dependent effects on the cortical substrates of crowding.

  19. Cortical organization in insectivora: the parallel evolution of the sensory periphery and the brain.

    PubMed

    Catania, K C

    2000-06-01

    Insectivores are traditionally described as a primitive group that has not changed much in the course of mammalian evolution. In contrast, recent studies reveal a great diversity of sensorimotor specializations among insectivores adapted to a number of different ecological niches, indicating that there has been significant diversification and change in the course of their evolution. Here the organization of sensory cortex is compared in the African hedgehog (Atelerix albiventris), the masked shrew (Sorex cinereus), the eastern mole (Scalopus aquaticus), and the star-nosed mole (Condylura cristata). Each of these four closely related species lives in a unique ecological niche, exhibits a different repertoire of behaviors, and has a different configuration of peripheral sensory receptors. Corresponding specializations of cortical sensory areas reveal a number of ways in which the cortex has evolved in parallel with changes to the sensory periphery. These specializations include expansion of cortical representations (cortical magnification), the addition or loss of cortical areas in the processing network, and the subdivision of areas into modules (barrels and stripes).

  20. Dynamic Re-calibration of Perceived Size in Fovea and Periphery through Predictable Size Changes.

    PubMed

    Valsecchi, Matteo; Gegenfurtner, Karl R

    2016-01-11

    The same object produces quite distinct images in the cortical representation, depending on whether it is looked at foveally or with the periphery, yet some form of size constancy prevents us from experiencing objects inflating or deflating as we move our eyes. According to the prominent sensorimotor account of vision by O'Regan and Noë [1], we constantly learn to discount the predictable sensory effects of motor actions, such as the projection of a stimulus on a larger cortical area as it gets foveated. Although previous studies have shown that foveal and parafoveal inputs can be associated in visual memory [2, 3], trans-saccadic prediction error could in principle re-calibrate even the appearance of peripheral and foveal stimuli. Here we introduce a new paradigm that induces such changes in the relative appearance of peripheral and foveal stimuli when directly compared. Repeated exposure to a trans-saccadic change in size, though unnoticed by most observers, induced a substantial modification of perceived size that lasted at least 1 day. Prediction is not limited to the motor system but can also occur for the sensory effects of external events, such as stimulus motion. We show that perceptual re-calibration can occur in the absence of eye movements if the change in size occurs predictably while objects move across the visual field. Perceptual uniformity emerges due to the continuously updated prediction of foveal appearance based on peripheral appearance. PMID:26711495

  1. Morphometry of E-PTA stained synapses at the periphery of pathological lesions.

    PubMed

    Bertoni-Freddari, Carlo; Fattoretti, Patrizia; Ricciuti, Riccardo; Vecchioni, Stefano; Casoli, Tiziana; Solazzi, Moreno; Ducati, Alessandro

    2002-01-01

    We carried out a novel application of the disector sampling and counting method, in a biopsy material from the pathologic human brain, to estimate the synaptic structural dynamics, quantitatively. Parietal cortex biopsies of adult (mean age: 40.0 years) and old (mean age: 66.2 years) patients having undergone surgical intervention were investigated. The tissue samples were excised at the periphery of meningioma masses. Synaptic contact zones were stained en bloc by the ethanol phosphotungstic acid (E-PTA) preferential technique which selectively enhances both the pre- and post-synaptic paramembranous material separated by a sharp cleft against a very faint background, thus facilitating and objectifying synaptic morphometry. The disector method, associated with currently used morphometric formulas, enabled us to measure the number of synapses/m3 of tissue (numeric density: Nv); the total area of the synaptic contact zones/m3 of tissue (surface density: Sv) and the average synaptic size (S). In old vs. adult patients, Nv decreased by 7.5% (Mean (SEM): Adult 2.0040(0.0452); Old 1.6780(0.0623)), while S increased by 17.5% (Adult 0.0203(0.0026); Old 0.0246(0.0035)). Sv did not show any age-related difference. The same negative correlation between Nv and S has also been reported in physiological aging, and this suggests the active presence of age-related synaptic restructuring mechanisms in the nervous tissue surrounding a tumoral mass.

  2. A Robust Speaker Identification System Using the Responses from a Model of the Auditory Periphery.

    PubMed

    Islam, Md Atiqul; Jassim, Wissam A; Cheok, Ng Siew; Zilany, Muhammad Shamsul Arefeen

    2016-01-01

    Speaker identification under noisy conditions is one of the challenging topics in the field of speech processing applications. Motivated by the fact that the neural responses are robust against noise, this paper proposes a new speaker identification system using 2-D neurograms constructed from the responses of a physiologically-based computational model of the auditory periphery. The responses of auditory-nerve fibers for a wide range of characteristic frequency were simulated to speech signals to construct neurograms. The neurogram coefficients were trained using the well-known Gaussian mixture model-universal background model classification technique to generate an identity model for each speaker. In this study, three text-independent and one text-dependent speaker databases were employed to test the identification performance of the proposed method. Also, the robustness of the proposed method was investigated using speech signals distorted by three types of noise such as the white Gaussian, pink, and street noises with different signal-to-noise ratios. The identification results of the proposed neural-response-based method were compared to the performances of the traditional speaker identification methods using features such as the Mel-frequency cepstral coefficients, Gamma-tone frequency cepstral coefficients and frequency domain linear prediction. Although the classification accuracy achieved by the proposed method was comparable to the performance of those traditional techniques in quiet, the new feature was found to provide lower error rates of classification under noisy environments. PMID:27392046

  3. A Robust Speaker Identification System Using the Responses from a Model of the Auditory Periphery

    PubMed Central

    Islam, Md. Atiqul; Jassim, Wissam A.; Cheok, Ng Siew; Zilany, Muhammad Shamsul Arefeen

    2016-01-01

    Speaker identification under noisy conditions is one of the challenging topics in the field of speech processing applications. Motivated by the fact that the neural responses are robust against noise, this paper proposes a new speaker identification system using 2-D neurograms constructed from the responses of a physiologically-based computational model of the auditory periphery. The responses of auditory-nerve fibers for a wide range of characteristic frequency were simulated to speech signals to construct neurograms. The neurogram coefficients were trained using the well-known Gaussian mixture model-universal background model classification technique to generate an identity model for each speaker. In this study, three text-independent and one text-dependent speaker databases were employed to test the identification performance of the proposed method. Also, the robustness of the proposed method was investigated using speech signals distorted by three types of noise such as the white Gaussian, pink, and street noises with different signal-to-noise ratios. The identification results of the proposed neural-response-based method were compared to the performances of the traditional speaker identification methods using features such as the Mel-frequency cepstral coefficients, Gamma-tone frequency cepstral coefficients and frequency domain linear prediction. Although the classification accuracy achieved by the proposed method was comparable to the performance of those traditional techniques in quiet, the new feature was found to provide lower error rates of classification under noisy environments. PMID:27392046

  4. New zero voltage switching DC converter with flying capacitors

    NASA Astrophysics Data System (ADS)

    Lin, Bor-Ren; Shiau, Tung-Yuan

    2016-04-01

    A new soft switching converter is presented for medium power applications. Two full-bridge converters are connected in series at high voltage side in order to limit the voltage stress of power switches at Vin/2. Therefore, power metal-oxide-semiconductor field-effect transistors (MOSFETs) with 600 V voltage rating can be adopted for 1200 V input voltage applications. In order to balance two input split capacitor voltages in every switching cycle, two flying capacitors are connected on the AC side of two full-bridge converters. Phase-shift pulse-width modulation (PS-PWM) is adopted to regulate the output voltage. Based on the resonant behaviour by the output capacitance of MOSFETs and the resonant inductance, active MOSFETs can be turned on under zero voltage switching (ZVS) during the transition interval. Thus, the switching losses of power MOSFETs are reduced. Two full-bridge converters are used in the proposed circuit to share load current and reduce the current stress of passive and active components. The circuit analysis and design example of the prototype circuit are provided in detail and the performance of the proposed converter is verified by the experiments.

  5. The ac53, ac78, ac101, and ac103 Genes Are Newly Discovered Core Genes in the Family Baculoviridae

    PubMed Central

    Garavaglia, Matías Javier; Miele, Solange Ana Belén; Iserte, Javier Alonso; Belaich, Mariano Nicolás

    2012-01-01

    The family Baculoviridae is a large group of insect viruses containing circular double-stranded DNA genomes of 80 to 180 kbp, which have broad biotechnological applications. A key feature to understand and manipulate them is the recognition of orthology. However, the differences in gene contents and evolutionary distances among the known members of this family make it difficult to assign sequence orthology. In this study, the genome sequences of 58 baculoviruses were analyzed, with the aim to detect previously undescribed core genes because of their remote homology. A routine based on Multi PSI-Blast/tBlastN and Multi HaMStR allowed us to detect 31 of 33 accepted core genes and 4 orthologous sequences in the Baculoviridae which were not described previously. Our results show that the ac53, ac78, ac101 (p40), and ac103 (p48) genes have orthologs in all genomes and should be considered core genes. Accordingly, there are 37 orthologous genes in the family Baculoviridae. PMID:22933288

  6. Organic Materials For Optical Switching

    NASA Technical Reports Server (NTRS)

    Cardelino, Beatriz H.

    1993-01-01

    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.

  7. Illuminated push-button switch

    NASA Technical Reports Server (NTRS)

    Iwagiri, T.

    1983-01-01

    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.

  8. Language Switching and Language Competition

    ERIC Educational Resources Information Center

    Macizo, Pedro; Bajo, Teresa; Paolieri, Daniela

    2012-01-01

    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…

  9. Abacus switch: a new scalable multicast ATM switch

    NASA Astrophysics Data System (ADS)

    Chao, H. Jonathan; Park, Jin-Soo; Choe, Byeong-Seog

    1995-10-01

    This paper describes a new architecture for a scalable multicast ATM switch from a few tens to thousands of input ports. The switch, called Abacus switch, has a nonblocking memoryless switch fabric followed by small switch modules at the output ports; the switch has input and output buffers. Cell replication, cell routing, output contention resolution, and cell addressing are all performed distributedly in the Abacus switch so that it can be scaled up to thousnads input and output ports. A novel algorithm has been proposed to resolve output port contention while achieving input and output ports. A novel algorithm has been proposed to reolve output port contention while achieving input buffers sharing, fairness among the input ports, and multicast call splitting. The channel grouping concept is also adopted in the switch to reduce the hardware complexity and improve the switch's throughput. The Abacus switch has a regular structure and thus has the advantages of: 1) easy expansion, 2) relaxed synchronization for data and clock signals, and 3) building the switch fabric using existing CMOS technology.

  10. High gain GaAs photoconductive semiconductor switches: Switch longevity

    SciTech Connect

    Loubriel, G.M.; Zutavern, F.J.; Mar, A.

    1998-07-01

    Optically activated, high gain GaAs switches are being tested for many different pulsed power applications that require long lifetime (longevity). The switches have p and n contact metallization (with intentional or unintentional dopants) configured in such a way as to produce p-i-n or n-i-n switches. The longevity of the switches is determined by circuit parameters and by the ability of the contacts to resist erosion. This paper will describe how the switches performed in test-beds designed to measure switch longevity. The best longevity was achieved with switches made with diffused contacts, achieving over 50 million pulses at 10 A and over 2 million pulses at 80 A.

  11. System and component design and test of a 10 hp, 18,000 rpm AC dynamometer utilizing a high frequency AC voltage link, part 1

    NASA Technical Reports Server (NTRS)

    Lipo, Thomas A.; Alan, Irfan

    1991-01-01

    Hard and soft switching test results conducted with one of the samples of first generation MOS-controlled thyristor (MCTs) and similar test results with several different samples of second generation MCT's are reported. A simple chopper circuit is used to investigate the basic switching characteristics of MCT under hard switching and various types of resonant circuits are used to determine soft switching characteristics of MCT under both zero voltage and zero current switching. Next, operation principles of a pulse density modulated converter (PDMC) for three phase (3F) to 3F two-step power conversion via parallel resonant high frequency (HF) AC link are reviewed. The details for the selection of power switches and other power components required for the construction of the power circuit for the second generation 3F to 3F converter system are discussed. The problems encountered in the first generation system are considered. Design and performance of the first generation 3F to 3F power converter system and field oriented induction moter drive based upon a 3 kVA, 20 kHz parallel resonant HF AC link are described. Low harmonic current at the input and output, unity power factor operation of input, and bidirectional flow capability of the system are shown via both computer and experimental results. The work completed on the construction and testing of the second generation converter and field oriented induction motor drive based upon specifications for a 10 hp squirrel cage dynamometer and a 20 kHz parallel resonant HF AC link is discussed. The induction machine is designed to deliver 10 hp or 7.46 kW when operated as an AC-dynamo with power fed back to the source through the converter. Results presented reveal that the proposed power level requires additional energy storage elements to overcome difficulties with a peak link voltage variation problem that limits reaching to the desired power level. The power level test of the second generation converter after the

  12. ACS Expands Role In High School Chemistry.

    ERIC Educational Resources Information Center

    Chemical and Engineering News, 1979

    1979-01-01

    Describes some of the services and programs of special interests to high school chemistry teachers that are being provided by ACS, and meant to make ACS membership more attractive to the teachers. (GA)

  13. Sonic crystal acoustic switch device.

    PubMed

    Alagoz, Serkan; Alagoz, Baris Baykant

    2013-06-01

    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.

  14. High gain photoconductive semiconductor switching

    SciTech Connect

    Zutavern, F.J.; Loubriel, G.M.; O'Malley, M.W.; Helgeson, W.D.; McLaughlin, D.L.

    1991-01-01

    Switching properties are reported for high gain photoconductive semiconductor switches (PCSS). A 200 ps pulse width laser was used in tests to examine the relations between electric field, rise time, delay, and minimum optical trigger energy for switches which reached 80 kV in a 50 {Omega} transmission line with rise times as short as 600 ps. Infrared photoluminescence was imaged during high gain switching providing direct evidence for current filamentation. Implications of these measurements for the theoretical understanding and practical development of these switches are discussed. 16 refs., 10 figs.

  15. Neurotransmitter Switching? No Surprise

    PubMed Central

    Spitzer, Nicholas C.

    2015-01-01

    Among the many forms of brain plasticity, changes in synaptic strength and changes in synapse number are particularly prominent. However, evidence for neurotransmitter respecification or switching has been accumulating steadily, both in the developing nervous system and in the adult brain, with observations of transmitter addition, loss, or replacement of one transmitter with another. Natural stimuli can drive these changes in transmitter identity, with matching changes in postsynaptic transmitter receptors. Strikingly, they often convert the synapse from excitatory to inhibitory or vice versa, providing a basis for changes in behavior in those cases in which it has been examined. Progress has been made in identifying the factors that induce transmitter switching and in understanding the molecular mechanisms by which it is achieved. There are many intriguing questions to be addressed. PMID:26050033

  16. MULTIPLE SPARK GAP SWITCH

    DOEpatents

    Schofield, A.E.

    1958-07-22

    A multiple spark gap switch of unique construction is described which will permit controlled, simultaneous discharge of several capacitors into a load. The switch construction includes a disc electrode with a plurality of protuberances of generally convex shape on one surface. A firing electrode is insulatingly supponted In each of the electrode protuberances and extends substantially to the apex thereof. Individual electrodes are disposed on an insulating plate parallel with the disc electrode to form a number of spark gaps with the protuberances. These electrodes are each connected to a separate charged capacitor and when a voltage ls applied simultaneously between the trigger electrodes and the dlsc electrode, each spark gap fires to connect its capacitor to the disc electrode and a subsequent load.

  17. Plasma opening switch

    DOEpatents

    Savage, Mark E.; Mendel, Jr., Clifford W.

    2001-01-01

    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.

  18. Cryogenic switched MOSFET characterization

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Both p channel and n channel enhancement mode MOSFETs can be readily switched on and off at temperatures as low as 2.8 K so that switch sampled readout of a VLWIR Ge:Ga focal plane is electronically possible. Noise levels as low as 100 rms electrons per sample (independent of sample rate) can be achieved using existing p channel MOSFETs, at overall rates up to 30,000 samples/second per multiplexed channel (e.g., 32 detectors at a rate of almost 1,000 frames/second). Run of the mill devices, including very low power dissipation n channel FETs would still permit noise levels of the order of 500 electrons/sample.

  19. A plasmonic Fano switch.

    PubMed

    Chang, Wei-Shun; Lassiter, J Britt; Swanglap, Pattanawit; Sobhani, Heidar; Khatua, Saumyakanti; Nordlander, Peter; Halas, Naomi J; Link, Stephan

    2012-09-12

    Plasmonic clusters can support Fano resonances, where the line shape characteristics are controlled by cluster geometry. Here we show that clusters with a hemicircular central disk surrounded by a circular ring of closely spaced, coupled nanodisks yield Fano-like and non-Fano-like spectra for orthogonal incident polarization orientations. When this structure is incorporated into an uniquely broadband, liquid crystal device geometry, the entire Fano resonance spectrum can be switched on and off in a voltage-dependent manner. A reversible transition between the Fano-like and non-Fano-like spectra is induced by relatively low (∼6 V) applied voltages, resulting in a complete on/off switching of the transparency window. PMID:22924610

  20. Switched matrix accelerator

    SciTech Connect

    Whittum, David H.; Tantawi, Sami G.

    2001-01-01

    We describe a new concept for a microwave circuit functioning as a charged-particle accelerator at mm wavelengths, permitting an accelerating gradient higher than conventional passive circuits can withstand consistent with cyclic fatigue. The device provides acceleration for multiple bunches in parallel channels, and permits a short exposure time for the conducting surface of the accelerating cavities. Our analysis includes scalings based on a smooth transmission line model and a complementary treatment with a coupled-cavity simulation. We also provide an electromagnetic design for the accelerating structure, arriving at rough dimensions for a seven-cell accelerator matched to standard waveguide and suitable for bench tests at low power in air at 91.392 GHz. A critical element in the concept is a fast mm-wave switch suitable for operation at high power, and we present the considerations for implementation in an H-plane tee. We discuss the use of diamond as the photoconductor switch medium.

  1. Switched Matrix Accelerator

    SciTech Connect

    Whittum, David H

    2000-10-04

    We describe a new concept for a microwave circuit functioning as a charged-particle accelerator at mm-wavelengths, permitting an accelerating gradient higher than conventional passive circuits can withstand consistent with cyclic fatigue. The device provides acceleration for multiple bunches in parallel channels, and permits a short exposure time for the conducting surface of the accelerating cavities. Our analysis includes scalings based on a smooth transmission line model and a complementary treatment with a coupled-cavity simulation. We provide also an electromagnetic design for the accelerating structure, arriving at rough dimensions for a seven-cell accelerator matched to standard waveguide and suitable for bench tests at low power in air at 91.392. GHz. A critical element in the concept is a fast mm-wave switch suitable for operation at high-power, and we present the considerations for implementation in an H-plane tee. We discuss the use of diamond as the photoconductor switch medium.

  2. A plasmonic Fano switch.

    PubMed

    Chang, Wei-Shun; Lassiter, J Britt; Swanglap, Pattanawit; Sobhani, Heidar; Khatua, Saumyakanti; Nordlander, Peter; Halas, Naomi J; Link, Stephan

    2012-09-12

    Plasmonic clusters can support Fano resonances, where the line shape characteristics are controlled by cluster geometry. Here we show that clusters with a hemicircular central disk surrounded by a circular ring of closely spaced, coupled nanodisks yield Fano-like and non-Fano-like spectra for orthogonal incident polarization orientations. When this structure is incorporated into an uniquely broadband, liquid crystal device geometry, the entire Fano resonance spectrum can be switched on and off in a voltage-dependent manner. A reversible transition between the Fano-like and non-Fano-like spectra is induced by relatively low (∼6 V) applied voltages, resulting in a complete on/off switching of the transparency window.

  3. CREE: Making the Switch

    SciTech Connect

    Grider, David; Palmer, John

    2014-03-06

    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.

  4. CREE: Making the Switch

    ScienceCinema

    Grider, David; Palmer, John

    2016-07-12

    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.

  5. Automatic switching matrix

    DOEpatents

    Schlecht, Martin F.; Kassakian, John G.; Caloggero, Anthony J.; Rhodes, Bruce; Otten, David; Rasmussen, Neil

    1982-01-01

    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.

  6. Composite Material Switches

    NASA Technical Reports Server (NTRS)

    Javadi, Hamid (Inventor)

    2001-01-01

    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.

  7. Automatic selection of switching paths

    NASA Astrophysics Data System (ADS)

    Meyer, B. A.

    A unique solution is presented to the problem of switching path selection through an analog switch complex. Known as the ROUTER, the software package performs a dynamic allocation of switching paths at the time that an analog signal connection is required. The ROUTER also chooses the type of relay that is appropriate to the signal being transmitted. Different types of switches are furnished for small signal, RF, video, power, or logic signals. Devices using a multiple number of leads, such as synchros or resolvers, are switched as a single unit. The algorithm used by the ROUTER is based on a tree search and connection technique. The interconnections of the hardware switches and devices are described by a connection matrix as a set of data structures. Each node of the switching complex is described in terms of its connectivity and attributes.

  8. Evolution of genetic switch complexity

    PubMed Central

    Broussard, Gregory W.; Hatfull, Graham F.

    2013-01-01

    The circuitry of the phage λ genetic switch determining the outcome of lytic or lysogenic growth is well-integrated and complex, raising the question as to how it evolved. It is plausible that it arose from a simpler ancestral switch with fewer components that underwent various additions and refinements, as it adapted to vast numbers of different hosts and conditions. We have recently identified a new class of genetic switches found in mycobacteriophages and other prophages, in which immunity is dependent on integration. These switches contain only three genes (integrase, repressor and cro) and represent a major departure from the λ-like circuitry, lacking many features such as xis, cII and cIII. These small self-contained switches represent an unrealized, elegant circuitry for controlling infection outcome. In this addendum, we propose a model of possible events in the evolution of a complex λ-like switch from a simpler integration-dependent switch. PMID:23819104

  9. Ultrafast gas switching experiments

    SciTech Connect

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

    1993-08-01

    We describe 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. The highly overvolted peaking gaps produce powerful electromagnetic pulses with risetimes < 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. We have produced and accurately measured pulses with 50 to 100 ps risetimes to peak levels of 75 to 160 kV at pulse repetition frequencies (PRF) to 1 kHz. 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 technology to practical systems antennas and bounded wave developed a thyristor/pulse transformer based system using a highly overvolted cable switch. This pulser driving a Sandia-designed TEM cell, provides an ultra wideband impulse with < 200 ps risetime to the test object at a PRF > Khz at > 100 kV/m E field.

  10. Ultrafast gas switching experiments

    SciTech Connect

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

    1996-11-01

    We describe 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. The highly overvolted peaking gaps produce powerful electromagnetic pulses with risetimes < 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. We have produced and accurately measured pulses with 50 to 100 ps risetimes to peak levels of 75 to 160 kV at pulse repetition frequencies (PRF) to I kHz. A unique gas switch was developed to hold off hundreds of kV with parasitic inductance less than I nH. An advanced diagnostic system using Fourier compensation was developed to measure single-shot risetimes below 35 ps. The complete apparatus is described and wave forms are presented. The measured data are compared with a theoretical model which predicts key features including dependence on gas species and pressure. We have applied this technology to practical systems driving ultrawideband radiating antennas and bounded wave simulators. For example, we have developed a thyristor/pulse transformer based system using a highly overvolted cable switch. This pulser driving a Sandia- designed TEM cell, provides an ultra wideband impulse with < 200 ps risetime to the test object at a PRF > 1 kHz at > 100 kV/m E field.

  11. "Platform switching": serendipity.

    PubMed

    Kalavathy, N; Sridevi, J; Gehlot, Roshni; Kumar, Santosh

    2014-01-01

    Implant dentistry is the latest developing field in terms of clinical techniques, research, material science and oral rehabilitation. Extensive work is being done to improve the designing of implants in order to achieve better esthetics and function. The main drawback with respect to implant restoration is achieving good osseointegration along with satisfactory stress distribution, which in turn will improve the prognosis of implant prosthesis by reducing the crestal bone loss. Many concepts have been developed with reference to surface coating of implants, surgical techniques for implant placement, immediate and delayed loading, platform switching concept, etc. This article has made an attempt to review the concept of platform switching was in fact revealed accidentally due to the nonavailability of the abutment appropriate to the size of the implant placed. A few aspect of platform switching, an upcoming idea to reduce crestal bone loss have been covered. The various methods used for locating and preparing the data were done through textbooks, Google search and related articles. PMID:24992863

  12. Ferroelectric switching of elastin

    PubMed Central

    Liu, Yuanming; Cai, Hong-Ling; Zelisko, Matthew; Wang, Yunjie; Sun, Jinglan; Yan, Fei; Ma, Feiyue; Wang, Peiqi; Chen, Qian Nataly; Zheng, Hairong; Meng, Xiangjian; Sharma, Pradeep; Zhang, Yanhang; Li, Jiangyu

    2014-01-01

    Ferroelectricity has long been speculated to have important biological functions, although its very existence in biology has never been firmly established. Here, we present compelling evidence that elastin, the key ECM protein found in connective tissues, is ferroelectric, and we elucidate the molecular mechanism of its switching. Nanoscale piezoresponse force microscopy and macroscopic pyroelectric measurements both show that elastin retains ferroelectricity at 473 K, with polarization on the order of 1 μC/cm2, whereas coarse-grained molecular dynamics simulations predict similar polarization with a Curie temperature of 580 K, which is higher than most synthetic molecular ferroelectrics. The polarization of elastin is found to be intrinsic in tropoelastin at the monomer level, analogous to the unit cell level polarization in classical perovskite ferroelectrics, and it switches via thermally activated cooperative rotation of dipoles. Our study sheds light onto a long-standing question on ferroelectric switching in biology and establishes ferroelectricity as an important biophysical property of proteins. This is a critical first step toward resolving its physiological significance and pathological implications. PMID:24958890

  13. Extended lifetime railgap switch

    SciTech Connect

    Cohn, D.B.; Mendoza, P.J.

    1988-02-02

    In a railgap switch of the type having an elongate blade electrode made of conductive material, an elongate housing made of insulating material for supporting the blade electrode and plate electrode in opposed relation extending in the same direction with the blade centered over the plate and separated therefrom by a gap, and a gas filling the housing and the gap, the gas being selected to breakdown and switch from a highly insulative state to a highly conductive state upon application of a high voltage across the blade and plate electrodes, the improvement is described comprising: forming the blade with laterally extending transverse wing portions at the edge of the blade and adjacent the gap so as to extend in spaced parallel relation to the surface of the plate, the blade generally following the contour thereof to form an inverted T-shape structure with the wing portions extending transversely of the elongate dimension of the blade. The wing portions terminating in a pair of spaced parallel edges extending along the elongate direction of the blade to thereby create two spaced elongate edges along which arcs form serving to divide the erosion effects of discharge between them, the current through each edge being one-half of that in single-edge devices with ablation wear reduced accordingly to give significantly larger switch lifetime. The blade and wing portions limiting ablation erosion of the edges in a direction generally align with the plate contour so that the edge-to-plate separation remains substantially constant.

  14. Cygnus Diverter Switch Analysis

    SciTech Connect

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

    2008-02-01

    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.

  15. Multiwavelength study of 20 jets that emanate from the periphery of active regions

    NASA Astrophysics Data System (ADS)

    Mulay, Sargam M.; Tripathi, Durgesh; Del Zanna, Giulio; Mason, Helen

    2016-05-01

    Aims: We present a multiwavelength analysis of 20 EUV jets which occurred at the periphery of active regions close to sunspots. We discuss the physical parameters of the jets and their relation with other phenomena such as Hα surges, nonthermal type-III radio bursts and hard X-ray (HXR) emission. Methods: These jets were observed between August 2010 and June 2013 by the Atmospheric Imaging Assembly (AIA) instrument that is onboard the Solar Dynamic Observatory (SDO). We selected events that were observed on the solar disk within +/-60° latitude. Using AIA wavelength channels that are sensitive to coronal temperatures, we studied the temperature distribution in the jets using the line of sight (LOS) differential emission measure (DEM) technique. We also investigated the role of the photospheric magnetic field using the LOS magnetogram data from the Helioseismic and Magnetic Imager (HMI) onboard SDO. Results: It has been observed that most of the jets originated from the western periphery of active regions. Their lifetimes range from 5 to 39 min with an average of 18 min and their velocities range from 87 to 532 km s-1 with an average of 271 km s-1. All the jets are co-temporally associated with Hα surges. Most of the jets are co-temporal with nonthermal type-III radio bursts observed by the Wind/WAVES spacecraft in the frequency range from 20 kHz to 13 MHz. We confirm the source region of these bursts using the potential field source surface (PFSS) technique. Using Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observations, we found that half of the jets produced HXR emission and they often shared the same source region as the HXR emission (6-12 keV). Ten out of 20 events showed that the jets originated in a region of flux cancellation and six jets in a region of flux emergence. Four events showed flux emergence and then cancellation during the jet evolution. DEM analyses showed that for most of the spires of the jets, the DEM peaked at around log

  16. Fused thiophene and its periphery fluorinated substitution derivatives: a theoretical study for organic semiconductors

    NASA Astrophysics Data System (ADS)

    Wei, Hui-Ling; Shi, Ya-Rui; Liu, Yu-Fang

    2015-06-01

    A series of phenyl end-capped derivatives of benzo[d,d‧]thieno[3,2-b4,5- b‧]dithiophene (BTDT) with periphery-fluorinated substitutions (PFS) were systematically investigated by using density functional theory (DFT) combined with the Marcus-Hush electron transfer theory. The substituting effects of PFS were discussed. Compared with the original compounds, (i) the PFS compounds have a relatively higher efficiency of charge transport, lower barriers of electron injection, and larger HOMO-LUMO gaps; (ii) the air-stability and the device performance are enhanced by PFS; and (iii) the HOMO-LUMO transitions in the absorption spectrum of the PFS compounds show an obvious blue-shift trend. The perfluorophenylbisbenzo[d, d‧]thieno[3,2-b4,5-b‧]dithiophene (BpF-BTDT) is found to be the most stable and most effective compound in charge transport among the investigated compounds, and it is suggested as an ambipolar semiconducting material. The results of electronic coupling of the bisbenzo[d, d‧]thieno[3,2-b 4,5- b‧]dithiophene (BBTDT) derivatives show that the orbital interaction is mainly contributed by the neighboring molecule in the two dimensional (2D) layer. The PFS compounds have lower oxidization potential, ionization potential, and electron affinity values than the corresponding original ones, which suggest that fluorination can enhance the performance of the thiophene-based organic solar cells. These findings provide a better understanding of the PFS effects on organic semiconductors and may help to design high-performance semiconductor materials.

  17. Competition between core and periphery-based processes in warm convective clouds - from invigoration to suppression

    NASA Astrophysics Data System (ADS)

    Dagan, G.; Koren, I.; Altaratz, O.

    2015-03-01

    How do changes in the amount and properties of aerosol affect warm clouds? Recent studies suggest that they have opposing effects. Some suggest that an increase in aerosol loading leads to enhanced evaporation and therefore smaller clouds, whereas other studies suggest clouds' invigoration. In this study, using an axisymmetric bin-microphysics cloud model, we propose a theoretical scheme that analyzes the evolution of key processes in warm clouds, under different aerosol loading and environmental conditions, to explain this contradiction. Such an analysis of the key processes reveals a robust reversal in the trend of the clouds' response to an increase in aerosol loading. When aerosol conditions are shifted from superpristine to slightly polluted, the clouds formed are deeper and have larger water mass. Such a trend continues up to an optimal concentration (Nop) that allows the cloud to achieve a maximal water mass. Hence, for any concentration below Nop the cloud formed contains less mass and therefore can be considered as aerosol-limited, whereas for concentrations greater thanNop cloud periphery processes, such as enhanced entrainment and evaporation, take over leading to cloud suppression. We show that Nop is a function of the thermodynamic conditions (temperature and humidity profiles). Thus, profiles that favor deeper clouds would dictate larger values of Nop, whereas for profiles of shallow convective clouds, Nop corresponds to the pristine range of the aerosol loading. Such a view of a trend reversal, marked by the optimal concentration, Nop, helps one to bridge the gap between the contradictory results of numerical models and observations. Satellite studies are biased in favor of larger clouds that are characterized by larger Nop values and therefore invigoration is observed. On the other hand, modeling studies of cloud fields are biased in favor of small, mostly trade-like convective clouds, which are characterized by low Nop values (in the pristine range

  18. Competition between core and periphery-based processes in warm convective clouds - from invigoration to suppression

    NASA Astrophysics Data System (ADS)

    Dagan, G.; Koren, I.; Altaratz, O.

    2014-09-01

    How do changes in the amount and properties of aerosol affect warm clouds? Recent studies suggest that they have opposing effects. Some suggest that an increase in aerosol loading leads to enhanced evaporation and therefore smaller clouds, whereas other studies suggest clouds' invigoration. In this study, using a bin-microphysics cloud model, we propose a theoretical scheme that analyzes the evolution of key processes in warm clouds, under different aerosol loading and environmental conditions, to explain this contradiction. Such a framework reveals a robust reversal in the trend of the clouds' response to an increase in aerosol loading. When aerosol conditions are shifted from super-pristine to slightly pollute, the clouds formed are deeper and have a larger water mass. Such a trend continues up to an optimal concentration (Nop) that allows the cloud to achieve a maximal water mass. Hence, for any concentration below Nop the cloud formed contains less mass and therefore can be considered as aerosol limited, whereas for concentrations greater than Nop cloud periphery processes, such as enhanced entrainment, take over leading to cloud suppression. We show that Nop is a function of the thermodynamic conditions (temperature and humidity profiles). Thus, profiles that favor deeper clouds would dictate larger values of Nop, whereas for profiles of shallow convective clouds, Nop corresponds to the pristine range of the aerosol loading. Such a view of a trend reversal, marked by the optimal concentration, Nop, helps one to bridge the gap between the contradictory results of numerical models and observations. Satellite studies are biased in favor of larger clouds that are characterized by larger Nop values and therefore invigoration is observed. On the other hand, modeling studies are biased in favor of small, mostly trade-like convective clouds, which are characterized by low Nop values (in the pristine range), and therefore cloud suppression is mostly reported as a

  19. The importance of an alternative for sustainability of agriculture around the periphery of the Amazon rainforest.

    PubMed

    Moura, Emanoel G; Sena, Virley G L; Corrêa, Mariana S; Aguiar, Alana das C F

    2013-04-01

    The unsustainable use of the soil of the deforested area at the Amazonian border is one of the greatest threats to the rainforest, because it is the predominant cause of shifting cultivation in the region. The sustainable management of soils with low natural fertility is a major challenge for smallholder agriculture in the humid tropics. In the periphery of Brazilian Amazonia, agricultural practices that are recommended for the Brazilian savannah, such as saturating soils with soluble nutrients do not ensure the sustainability of agroecosystems. Improvements in the tilled topsoil cannot be maintained if deterioration of the porous soil structure is not prevented and nutrient losses in the root zone are not curtailed. The information gleaned from experiments affirms that in the management of humid tropical agrosystems, the processes resulting from the interaction between climatic factors and indicators of soil quality must be taken into consideration. It must be remembered that these interactions manifest themselves in ways that cannot be predicted from the paradigm established in the other region like the southeast of Brazil, which is based only on improving the chemical indicators of soil quality. The physical indicators play important role in the sustainable management of the agrosystems of the region and for these reasons must be considered. Therefore, alley cropping is a potential substitute for slash and burn agriculture in the humid tropics with both environmental and agronomic advantages, due to its ability to produce a large amount of residues on the soil surface and its effect on the increase of economic crop productivity in the long term. The article presents some promising patents on the importance of an alternative for sustainability of agriculture. PMID:23305424

  20. The importance of an alternative for sustainability of agriculture around the periphery of the Amazon rainforest.

    PubMed

    Moura, Emanoel G; Sena, Virley G L; Corrêa, Mariana S; Aguiar, Alana das C F

    2013-04-01

    The unsustainable use of the soil of the deforested area at the Amazonian border is one of the greatest threats to the rainforest, because it is the predominant cause of shifting cultivation in the region. The sustainable management of soils with low natural fertility is a major challenge for smallholder agriculture in the humid tropics. In the periphery of Brazilian Amazonia, agricultural practices that are recommended for the Brazilian savannah, such as saturating soils with soluble nutrients do not ensure the sustainability of agroecosystems. Improvements in the tilled topsoil cannot be maintained if deterioration of the porous soil structure is not prevented and nutrient losses in the root zone are not curtailed. The information gleaned from experiments affirms that in the management of humid tropical agrosystems, the processes resulting from the interaction between climatic factors and indicators of soil quality must be taken into consideration. It must be remembered that these interactions manifest themselves in ways that cannot be predicted from the paradigm established in the other region like the southeast of Brazil, which is based only on improving the chemical indicators of soil quality. The physical indicators play important role in the sustainable management of the agrosystems of the region and for these reasons must be considered. Therefore, alley cropping is a potential substitute for slash and burn agriculture in the humid tropics with both environmental and agronomic advantages, due to its ability to produce a large amount of residues on the soil surface and its effect on the increase of economic crop productivity in the long term. The article presents some promising patents on the importance of an alternative for sustainability of agriculture.

  1. Dendritic Cells in the Periphery Control Antigen-Specific Natural and Induced Regulatory T Cells

    PubMed Central

    Yamazaki, Sayuri; Morita, Akimichi

    2013-01-01

    Dendritic cells (DCs) are specialized antigen-presenting cells that regulate both immunity and tolerance. DCs in the periphery play a key role in expanding naturally occurring Foxp3+ CD25+ CD4+ regulatory T cells (Natural T-regs) and inducing Foxp3 expression (Induced T-regs) in Foxp3− CD4+ T cells. DCs are phenotypically and functionally heterogeneous, and further classified into several subsets depending on distinct marker expression and their location. Recent findings indicate the presence of specialized DC subsets that act to expand Natural T-regs or induce Foxp3+ T-regs from Foxp3− CD4+ T cells. For example, two major subsets of DCs in lymphoid organs act differentially in inducing Foxp3+ T-regs from Foxp3− cells or expanding Natural T-regs with model-antigen delivery by anti-DC subset monoclonal antibodies in vivo. Furthermore, DCs expressing CD103 in the intestine induce Foxp3+ T-regs from Foxp3− CD4+ T cells with endogenous TGF-β and retinoic acid. In addition, antigen-presenting DCs have a capacity to generate Foxp3+ T-regs in the oral cavity where many antigens and commensals exist, similar to intestine and skin. In skin and skin-draining lymph nodes, at least six DC subsets have been identified, suggesting a complex DC-T-reg network. Here, we will review the specific activity of DCs in expanding Natural T-regs and inducing Foxp3+ T-regs from Foxp3− precursors, and further discuss the critical function of DCs in maintaining tolerance at various locations including skin and oral cavity. PMID:23801989

  2. Analysis of core-periphery organization in protein contact networks reveals groups of structurally and functionally critical residues.

    PubMed

    Isaac, Arnold Emerson; Sinha, Sitabhra

    2015-10-01

    The representation of proteins as networks of interacting amino acids, referred to as protein contact networks (PCN), and their subsequent analyses using graph theoretic tools, can provide novel insights into the key functional roles of specific groups of residues. We have characterized the networks corresponding to the native states of 66 proteins (belonging to different families) in terms of their core-periphery organization. The resulting hierarchical classification of the amino acid constituents of a protein arranges the residues into successive layers - having higher core order - with increasing connection density, ranging from a sparsely linked periphery to a densely intra-connected core (distinct from the earlier concept of protein core defined in terms of the three-dimensional geometry of the native state, which has least solvent accessibility). Our results show that residues in the inner cores are more conserved than those at the periphery. Underlining the functional importance of the network core, we see that the receptor sites for known ligand molecules of most proteins occur in the innermost core. Furthermore, the association of residues with structural pockets and cavities in binding or active sites increases with the core order. From mutation sensitivity analysis, we show that the probability of deleterious or intolerant mutations also increases with the core order. We also show that stabilization centre residues are in the innermost cores, suggesting that the network core is critically important in maintaining the structural stability of the protein. A publicly available Web resource for performing core-periphery analysis of any protein whose native state is known has been made available by us at http://www.imsc.res.in/ ~sitabhra/proteinKcore/index.html.

  3. A study of some features of ac and dc electric power systems for a space station

    NASA Technical Reports Server (NTRS)

    Hanania, J. I.

    1983-01-01

    This study analyzes certain selected topics in rival dc and high frequency ac electric power systems for a Space Station. The interaction between the Space Station and the plasma environment is analyzed, leading to a limit on the voltage for the solar array and a potential problem with resonance coupling at high frequencies. Certain problems are pointed out in the concept of a rotary transformer, and further development work is indicated in connection with dc circuit switching, special design of a transmission conductor for the ac system, and electric motors. The question of electric shock hazards, particularly at high frequency, is also explored. and a problem with reduced skin resistance and therefore increased hazard with high frequency ac is pointed out. The study concludes with a comparison of the main advantages and disadvantages of the two rival systems, and it is suggested that the choice between the two should be made after further studies and development work are completed.

  4. Trypanosoma cruzi DNA replication includes the sequential recruitment of pre-replication and replication machineries close to nuclear periphery

    PubMed Central

    Calderano, Simone Guedes; de Melo Godoy, Patrícia Diogo; Motta, Maria Cristina M; Mortara, Renato A; Schenkman, Sergio

    2011-01-01

    In eukaryotes, many nuclear processes are spatially compartmentalized. Previously, we have shown that in Trypanosoma cruzi, an early-divergent eukaryote, DNA replication occurs at the nuclear periphery where chromosomes remain constrained during the S phase of the cell cycle. We followed Orc1/Cdc6, a pre-replication machinery component and the proliferating cell nuclear antigen (PCNA), a component of replication machinery, during the cell cycle of this protozoon. We found that, at the G1 stage, TcOrc1/Cdc6 and TcPCNA are dispersed throughout the nuclear space. During the G1/S transition, TcOrc1/Cdc6 migrates to a region close to nuclear periphery. At the onset of S phase, TcPCNA is loaded onto the DNA and remains constrained close to nuclear periphery. Finally, in G2, mitosis and cytokinesis, TcOrc1/Cdc6 and TcPCNA are dispersed throughout the nuclear space. Based on these findings, we propose that DNA replication in T. cruzi is accomplished by the organization of functional machineries in a spatial-temporal manner. PMID:21738836

  5. Inhibition of tyrosine kinase receptors by SU6668 promotes abnormal stromal development at the periphery of carcinomas

    PubMed Central

    Farace, P; Galiè, M; Merigo, F; Daducci, A; Calderan, L; Nicolato, E; Degrassi, A; Pesenti, E; Sbarbati, A; Marzola, P

    2009-01-01

    Dynamic contrast-enhanced (albumin-Gd-DTPA) magnetic resonance imaging, performed during 2 weeks of daily administration of an inhibitor of tyrosine kinase receptors (SU6668) in an HT-29 colon carcinoma model, revealed the onset of a hyper-enhancing rim, not observed in untreated tumours. To account for tissue heterogeneity in the quantitative analysis, we segmented tumours into three subunits automatically identified by cluster analysis of the enhancement curves using a k-means algorithm. Transendothelial permeability (Kps) and fractional plasma volume (fPV) were calculated in each subunit. An avascular and necrotic region, an intermediate zone and a well-vascularised periphery were reliably identified. During untreated tumour growth, the identified sub-regions did not substantially change their enhancement pattern. Treatment with SU6668 induced major changes at tumour periphery where a significant increase of Kps and fPV was observed with respect to control tumours. Histology revealed a sub-capsular layer composed of hyper-dense viable tumour cells in the periphery of untreated tumours. The rim of viable neoplastic cells was reduced in treated tumours, and replaced by loose connective tissue characterised by numerous vessels, which explains the observed hyper-enhancement. The present data show a peripheral abnormal development of cancer-associated stroma, indicative of an adaptive response to anti-angiogenic treatment. PMID:19384298

  6. Illusory movement of stationary stimuli in the visual periphery: evidence for a strong centrifugal prior in motion processing.

    PubMed

    Zhang, Ruyuan; Kwon, Oh-Sang; Tadin, Duje

    2013-03-01

    Visual input is remarkably diverse. Certain sensory inputs are more probable than others, mirroring statistical regularities of the visual environment. The visual system exploits many of these regularities, resulting, on average, in better inferences about visual stimuli. However, by incorporating prior knowledge into perceptual decisions, visual processing can also result in perceptions that do not match sensory inputs. Such perceptual biases can often reveal unique insights into underlying mechanisms and computations. For example, a prior assumption that objects move slowly can explain a wide range of motion phenomena. The prior on slow speed is usually rationalized by its match with visual input, which typically includes stationary or slow moving objects. However, this only holds for foveal and parafoveal stimulation. The visual periphery tends to be exposed to faster motions, which are biased toward centrifugal directions. Thus, if prior assumptions derive from experience, peripheral motion processing should be biased toward centrifugal speeds. Here, in experiments with human participants, we support this hypothesis and report a novel visual illusion where stationary objects in the visual periphery are perceived as moving centrifugally, while objects moving as fast as 7°/s toward fovea are perceived as stationary. These behavioral results were quantitatively explained by a Bayesian observer that has a strong centrifugal prior. This prior is consistent with both the prevalence of centrifugal motions in the visual periphery and a centrifugal bias of direction tuning in cortical area MT, supporting the notion that visual processing mirrors its input statistics.

  7. Simultaneous distribution of AC and DC power

    DOEpatents

    Polese, Luigi Gentile

    2015-09-15

    A system and method for the transport and distribution of both AC (alternating current) power and DC (direct current) power over wiring infrastructure normally used for distributing AC power only, for example, residential and/or commercial buildings' electrical wires is disclosed and taught. The system and method permits the combining of AC and DC power sources and the simultaneous distribution of the resulting power over the same wiring. At the utilization site a complementary device permits the separation of the DC power from the AC power and their reconstruction, for use in conventional AC-only and DC-only devices.

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

    SciTech Connect

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

    1997-12-01

    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.

  9. A series of dinuclear Dy(iii) complexes bridged by 2-methyl-8-hydroxylquinoline: replacement on the periphery coordinated β-diketonate terminal leads to different single-molecule magnetic properties.

    PubMed

    Zhang, Wan-Ying; Tian, Yong-Mei; Li, Hong-Feng; Chen, Peng; Sun, Wen-Bin; Zhang, Yi-Quan; Yan, Peng-Fei

    2016-03-01

    A series of HMq-bridged dinuclear dysprosium complexes, namely, [Dy(acac)2(CH3OH)]2(μ-HMq)2 (1), [Dy(DBM)2]2(μ-HMq)2(n-C6H14) (2), [Dy(hmac)2]2(μ-HMq)2 (3) and [Dy(hfac)3]2(μ-HMq)2 (4) (HMq = 2-methyl-8-hydroxyquinoline, acac = acetylacetone, DBM = dibenzoylmethane, hmac = hexamethylacetylacetonate and hfac = hexafluoroacetylacetonate), were structurally and magnetically characterized. X-ray crystallographic analyses of the structures reveal that HMq serves as the effective bridge to link two Dy(III) centers by means of the phenoxyl oxygen and nitrogen atoms and the periphery β-diketonate ligands complete the coordination sphere by bidentate oxygen atoms. The different substituents on the β-diketonate terminal lead to different coordination models mostly due to the steric hindrance of these substituents, and the electron-withdrawing or donating effects likely influence the strength of the ligand fields and the Dy(III) ion anisotropy. Measurements of alternating-current (ac) susceptibility on complexes 1-4 reveal that complexes 3 and 4 display significant zero-field single-molecule magnetic (SMM) behavior with barrier energy Ueff/kB = 14.8 K, τ0 = 1.8 × 10(-5) s and Ueff/kB = 9.2 K, τ0 = 1.7 × 10(-5) s, respectively, whereas 1 and 2 exhibit field-induced SMM behavior, and these differences are attributed to the alteration on the periphery β-diketonate ligands. Their distinct slow magnetic relaxation behaviors were related to their different individual Dy(III) ion magnetic anisotropy and intramolecular coupling, which were confirmed by ab initio calculations. PMID:26905041

  10. Task switching and the measurement of "switch costs".

    PubMed

    Wylie, G; Allport, A

    2000-01-01

    The measurement of "switch costs" is held to be of interest because, as is widely believed, they may reflect the control processes that are engaged when subjects switch between two (or more) competing tasks. [In task-switching experiments, the reaction time (RT) switch cost is typically measured as the difference in RT between switch and non-switch (repeat) trials.] In this report we focus on the RT switch costs that remain even after the subject has had some time to prepare for the shift of task, when the switch cost may be approximately asymptotic (so-called residual switch costs). Three experiments are presented. All three experiments used Stroop colour/word, and neutral stimuli. Participants performed the two tasks of word-reading and colour-naming in a regular, double alternation, using the "alternating runs" paradigm (R. D. Rogers & S. Monsell, 1995). The experiments were designed to test the hypothesis that RT switch costs depend on a form of proactive interference (PI) arising from the performance of a prior, competing task. A. Allport, E. A. Styles and S. Hsieh (1994) suggested that these PI effects resulted from "task-set inertia", that is, the persisting activation-suppression of competing task-sets, or competing task-processing pathways. The results confirmed the existence of long-lasting PI from the competing task as a major contributor to switch costs. Non-switch trials, used as the baseline in the measurement of switch costs, were also shown to be strongly affected by similar PI effects. However, task-set inertia was not sufficient to account for these results. The results appeared inconsistent also with all other previous models of task switching. A new hypothesis to explain these between-task interference effects was developed, based on the stimulus-triggered retrieval of competing stimulus-response (S-R) associations, acquired (or strengthened) in earlier trials. Consistent with this retrieval hypothesis, switch costs were shown to depend

  11. Anisotropic high temperature superconductors as variable resistors and switches

    SciTech Connect

    Boenig, H.J.; Daugherty, M.A.; Fleshler, S.; Maley, M.P.; Mueller, F.M.; Prenger, F.C.; Coulter, J.Y.

    1994-12-01

    Several anisotropic high temperature superconductors show critical current densities which are strongly dependent on the direction of an applied external magnetic field. The resistance of a sample can change by several orders of magnitude by applying a magnetic field. The potential for using the field dependent variable resistor or switch for applications in power systems is evaluated. Test results with small samples are presented. The requirements for large scale applications are outlined. The magnetic field triggering requirement, the frequency response of the device, use in 60 Hz ac circuits and heat transfer consideration are investigated. Several application examples are discussed. Use of variable resistor as a fault current limiter, as a switching element in rectifier circuitry and as an improved dump resistor for a superconducting magnet is presented.

  12. Biological switches and clocks

    PubMed Central

    Tyson, John J.; Albert, Reka; Goldbeter, Albert; Ruoff, Peter; Sible, Jill

    2008-01-01

    To introduce this special issue on biological switches and clocks, we review the historical development of mathematical models of bistability and oscillations in chemical reaction networks. In the 1960s and 1970s, these models were limited to well-studied biochemical examples, such as glycolytic oscillations and cyclic AMP signalling. After the molecular genetics revolution of the 1980s, the field of molecular cell biology was thrown wide open to mathematical modellers. We review recent advances in modelling the gene–protein interaction networks that control circadian rhythms, cell cycle progression, signal processing and the design of synthetic gene networks. PMID:18522926

  13. Neutron activated switch

    DOEpatents

    Barton, David M.

    1991-01-01

    A switch for reacting quickly to a neutron emission. A rod consisting of fissionable material is located inside a vacuum tight body. An adjustable contact is located coaxially at an adjustable distance from one end of the rod. Electrical leads are connected to the rod and to the adjustable contact. With a vacuum drawn inside the body, a neutron bombardment striking the rod causes it to heat and expand longitudinally until it comes into contact with the adjustable contact. This circuit closing occurs within a period of a few microseconds.

  14. Composite Thermal Switch

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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

  15. Power transistor switching characterization

    NASA Technical Reports Server (NTRS)

    Blackburn, D. L.

    1981-01-01

    The switching properties of power transistors are investigated. The devices studied were housed in IO-3 cases and were of an n(+)-p-n(-)-n(+) vertical dopant structure. The effects of the magnitude of the reverse-base current and temperature on the reverse-bias second breakdown characteristics are discussed. Brief discussions of device degradation due to second breakdown and of a constant voltage turn-off circuit are included. A description of a vacuum tube voltage clamp circuit which reduces clamped collector voltage overshoot is given.

  16. T lymphocytes in the murine vaginal mucosa are phenotypically distinct from those in the periphery.

    PubMed Central

    Fidel, P L; Wolf, N A; KuKuruga, M A

    1996-01-01

    The results from both clinical studies of women with recurrent vulvovaginal candidiasis and a murine model of experimental vaginitis indicate that systemic cell-mediated immunity may not represent a dominant host defense mechanism against vaginal infections by Candida albicans. Recent experimental evidence indicates the presence of local vaginal immune reactivity against C. albicans. The present study was designed to examine T-lymphocyte subpopulations in the vaginal mucosae of naive CBA/J mice. Vaginal lymphocytes (VL) were isolated by collagenase digestion of whole vaginal tissues. Cell populations were identified by flow cytometry, and the results were compared with those for both lymph node cells (LNC) and peripheral blood lymphocytes (PBL). The results of flow cytometry showed that 45% +/- 10% of lymphocytes in the vaginal mucosa are CD3+ compared with 75% +/- 5% in LNC and 50% +/- 5% in PBL. The majority (85%) of CD3+ VL are CD4+ and express the alpha/beta T-cell receptor (TCR), similar to the results for LNC and PBL. In contrast to LNC and PBL, VL contain a significantly higher percentage (15 to 20%) of gamma/delta TCR+ cells, 80% or more of which appear to express CD4. In addition, while CD4-CD8 cell ratios in LNC and PBL were 3:1 and 6:1, respectively, only 1% of VL expressed CD8, resulting in a CD4-CD8 cell ratio of > 100:1. Finally, while LNC and PBL recognized two epitope-distinct (GK 1.5 and 2B6) anti-CD4 antibodies, VL recognized only 2B6 anti-CD4 antibodies. Further analysis of VL showed that Thy-1 cells, but not CD4 cells, were reduced after intravaginal injection of complement-fixing anti-Thy-1.2 and GK 1.5 anti-CD4 antibodies, respectively. Taken together, these data suggest that T lymphocytes in the vaginal mucosae of mice are phenotypically distinct from those in the periphery and that CD4+ VL have an uncharacteristic or atypical expression of the CD4 receptor. PMID:8751931

  17. System for conveniently providing load testing termination of an AC power source having at least one battery

    NASA Astrophysics Data System (ADS)

    Morell, Wilbert J., III

    1995-05-01

    An AC uninterruptible power source is disclosed that provides multiphase power output signals for actual use and a selectable single phase power output signal for use in testing. The AC uninterruptible power source further comprises at least one battery. The single phase output signal is connected to a dummy load by means of a power switch of the break before make type. The invention further includes the dummy load as preferably having metering capabilities to measure the frequency, current, and voltage parameters of the single phase output signal. The arrangement of the present invention allows for the single phase output to be mated to the dummy load without the need of removing input power to the AC uninterruptible power source so as to reduce, or even eliminate, transient caused failures to the AC uninterruptible power source and to its sensitive load equipment which the power source services.

  18. A system for conveniently providing load testing termination of an AC power source having at least one battery

    NASA Astrophysics Data System (ADS)

    Morrell, Wilbert J., III

    1994-10-01

    An AC uninterruptible power source is disclosed that provides multi-phase power output signals for actual use and a selectable single phase power output signal for use in testing. The AC uninterruptible power source further comprises at least one battery. The single phase output signal is connected to a dummy load by means of a power switch of the break-before-make type. The invention further includes the dummy load as preferably having metering capabilities to measure the frequency, current, and voltage parameters of the single phase output signal. The arrangement of the present invention allows for the single phase output to be mated to the dummy load without the need of removing input power to the AC uninterruptible power source so as to reduce, or even eliminate, transient caused failures to the AC uninterruptible power source and to its sensitive load equipment which the power source services.

  19. Compound semiconductor optical waveguide switch

    DOEpatents

    Spahn, Olga B.; Sullivan, Charles T.; Garcia, Ernest J.

    2003-06-10

    An optical waveguide switch is disclosed which is formed from III-V compound semiconductors and which has a moveable optical waveguide with a cantilevered portion that can be bent laterally by an integral electrostatic actuator to route an optical signal (i.e. light) between the moveable optical waveguide and one of a plurality of fixed optical waveguides. A plurality of optical waveguide switches can be formed on a common substrate and interconnected to form an optical switching network.

  20. Double-injection, deep-impurity switch development

    NASA Technical Reports Server (NTRS)

    Whitson, D. W.

    1985-01-01

    The overall objective of this program was the development of device design and process techniques for the fabrication of a double-injection, deep-impurity (DI) sup 2 silicon switch that operates in the 2-10 kV range with conduction current values of 5 A at 2 kV and 1 A at 10 kV. Other major specifications include a holding voltage of 10 V with no gate current, 10 microsec switching time, and power dissipation of 50 W at 75 C. It was decided to concentrate on the lateral circular devices in order to optimize the gold diffusion. This resulted in devices that are much better switches (approx.1 micro sec switching time), and in a gold diffusion process that is much more controllable than those previously developed. Some results with injection-gated devices were also obtained. The current conduction for V less than VT was analyzed and seen to agree, for the most part, with Lampert's theory. Various sections of this report describe the device designs, wafer-processing techniques, and various measurements which include ac and dc characteristics and four-point probe.

  1. Input-current shaped ac to dc converters

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The problem of achieving near unity power factor while supplying power to a dc load from a single phase ac source of power is examined. Power processors for this application must perform three functions: input current shaping, energy storage, and output voltage regulation. The methods available for performing each of these three functions are reviewed. Input current shaping methods are either active or passive, with the active methods divided into buck-like and boost-like techniques. In addition to large reactances, energy storage methods include resonant filters, active filters, and active storage schemes. Fast voltage regulation can be achieved by post regulation or by supplementing the current shaping topology with an extra switch. Some indications of which methods are best suited for particular applications concludes the discussion.

  2. Development of AC and DC Power Supply Direct Interface Converter

    NASA Astrophysics Data System (ADS)

    Kato, Koji; Itoh, Jun-Ichi

    This paper proposes a novel control method for a direct interface converter for management of the energy flow in either an AC or DC supply. The proposed converter is constructed based on an indirect matrix converter. Therefore a proposed control strategy is based on an indirect control method with a triangular carrier wave. The basic operation of the proposed control method is confirmed by experimental results. In addition, this paper also proposes a commutation error compensation method of an output voltage error and an input current error for an indirect matrix converter. In the proposed method, the output voltage and input current error by the commutation can be compensated at the same time, because the PWM pulse of each switch is directly compensated. The validity of the proposed method is confirmed by experimental results. Those results prove that the proposed compensation method can decrease total harmonic distortion (THD) of the input and output current.

  3. Data center coolant switch

    SciTech Connect

    Iyengar, Madhusudan K.; Parida, Pritish R.; Schultz, Mark D.

    2015-10-06

    A data center cooling system is operated in a first mode; it has an indoor portion wherein heat is absorbed from components in the data center, and an outdoor heat exchanger portion wherein outside air is used to cool a first heat transfer fluid (e.g., water) present in at least the outdoor heat exchanger portion of the cooling system during the first mode. The first heat transfer fluid is a relatively high performance heat transfer fluid (as compared to the second fluid), and has a first heat transfer fluid freezing point. A determination is made that an appropriate time has been reached to switch from the first mode to a second mode. Based on this determination, the outdoor heat exchanger portion of the data cooling system is switched to a second heat transfer fluid, which is a relatively low performance heat transfer fluid, as compared to the first heat transfer fluid. It has a second heat transfer fluid freezing point lower than the first heat transfer fluid freezing point, and the second heat transfer fluid freezing point is sufficiently low to operate without freezing when the outdoor air temperature drops below a first predetermined relationship with the first heat transfer fluid freezing point.

  4. Small-Signal ac Analysis

    NASA Technical Reports Server (NTRS)

    Jagielski, James M.; Chen, Jess

    1987-01-01

    Program simulates power circuits and systems. Small Signal A.C. Analysis program (SSAC) valuable tool for design and analysis of electrical-power-system circuits. By combining "black box" power-system components operating in specified manner, user characterizes system modeled. Menu-driven program proved simple and cost effective in development and modification of arbitrary power-system configurations. Package includes sample data from Dynamic Explorer satellite family. Results compared favorable to calculations from such general circuit-analysis programs as SPICE. Written in FORTRAN 77.

  5. A high capacity satellite switched TDMA microwave switch matrix

    NASA Technical Reports Server (NTRS)

    Cory, B. J.; Berkowitz, M.

    1981-01-01

    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.

  6. Hybrid switch for resonant power converters

    DOEpatents

    Lai, Jih-Sheng; Yu, Wensong

    2014-09-09

    A hybrid switch comprising two semiconductor switches connected in parallel but having different voltage drop characteristics as a function of current facilitates attainment of zero voltage switching and reduces conduction losses to complement reduction of switching losses achieved through zero voltage switching in power converters such as high-current inverters.

  7. Effect of the magnetic material on AC losses in HTS conductors in AC magnetic field carrying AC transport current

    NASA Astrophysics Data System (ADS)

    Wan, Xing-Xing; Huang, Chen-Guang; Yong, Hua-Dong; Zhou, You-He

    2015-11-01

    This paper presents an investigation on the AC losses in several typical superconducting composite conductors using the H-formulation model. A single superconducting strip with ferromagnetic substrate or cores and a stack of coated conductors with ferromagnetic substrates are studied. We consider all the coated conductors carrying AC transport currents and simultaneously exposed to perpendicular AC magnetic fields. The influences of the amplitude, frequency, phase difference and ferromagnetic materials on the AC losses are investigated. The results show that the magnetization losses of single strip and stacked strips have similar characteristics. The ferromagnetic substrate can increase the magnetization loss at low magnetic field, and decrease the loss at high magnetic field. The ferromagnetic substrate can obviously increase the transport loss in stacked strips. The trends of total AC losses of single strip and stacked strips are similar when they are carrying current or exposed to a perpendicular magnetic field. The effect of the frequency on the total AC losses of single strip is related to the amplitude of magnetic field. The AC losses decrease with increasing frequency in low magnetic field region while increase in high magnetic field region. As the phase difference changes, there is a periodic variation for the AC losses. Moreover, when the strip is under only the transport current and magnetic field, the ferromagnetic cores will increase the AC losses for large transport current or field.

  8. Switching languages, switching palabras (words): an electrophysiological study of code switching.

    PubMed

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

    2002-02-01

    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 specifically enhanced the N400 response in both context types. Code switches, by contrast, elicited an increased negativity over left fronto-central sites in the regular nonidiomatic sentences (250-450 ms) and a large posterior positivity (450-850 ms) in both context types. In addition, both lexical and code switches elicited a late frontal positivity (650-850 ms) relative to expected completions, especially in idioms. Analysis of the individual response patterns showed correlations with vocabulary skills in English and in Spanish. Overall, the electrophysiological data suggest that for some speakers in some contexts, the processing of a code switch may actually be less costly than the processing of an unexpected within-language item.

  9. Convertible resistive switching characteristics between memory switching and threshold switching in a single ferritin-based memristor.

    PubMed

    Zhang, Chaochao; Shang, Jie; Xue, Wuhong; Tan, Hongwei; Pan, Liang; Yang, Xi; Guo, Shanshan; Hao, Jian; Liu, Gang; Li, Run-Wei

    2016-04-01

    A bio-memristor fabricated with ferritin exhibits novel resistive switching characteristics wherein memory switching and threshold switching are made steadily coexistent and inter-convertible through controlling the magnitude of compliance current presets.

  10. EDITORIAL: Molecular switches at surfaces Molecular switches at surfaces

    NASA Astrophysics Data System (ADS)

    Weinelt, Martin; von Oppen, Felix

    2012-10-01

    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

  11. ac electroosmosis in rectangular microchannels.

    PubMed

    Campisi, Michele; Accoto, Dino; Dario, Paolo

    2005-11-22

    Motivated by the growing interest in ac electroosmosis as a reliable no moving parts strategy to control fluid motion in microfluidic devices for biomedical applications, such as lab-on-a-chip, we study transient and steady-state electrokinetic phenomena (electroosmosis and streaming currents) in infinitely extended rectangular charged microchannels. With the aid of Fourier series and Laplace transforms we provide a general formal solution of the problem, which is used to study the time-dependent response to sudden ac applied voltage differences in case of finite electric double layer. The Debye-Huckel approximation has been adopted to allow for an algebraic solution of the Poisson-Boltzmann problem in Fourier space. We obtain the expressions of flow velocity profiles, flow rates, streaming currents, as well as expressions of the complex hydraulic and electrokinetic conductances. We analyze in detail the dependence of the electrokinetic conductance on the extension of linear dimensions relative to the Debye length, with an eye on finite electric double layer effects. PMID:16351310

  12. Switching Characteristics of Silica Nanoparticle-Doped Dual-Mode Liquid Crystal Device

    NASA Astrophysics Data System (ADS)

    Huang, Chi-Yen; Lai, Chien-Cheng; Huang, Yi-Jen; Chen, Jian-Hong

    2010-02-01

    We investigate the switching characteristics of a silica nanoparticle-doped dual-mode liquid crystal (LC) display. In the multistable mode, aggregated silica networks impede the relaxation of LCs and increase the response time of the cell. A low-frequency AC pulse voltage rotates LCs and breaks aggregated silica networks. The breaking of silica networks accelerates the relaxation of LCs and hence decreases the response time of the cell. The low-frequency AC pulse voltage gives the cell a fast response time of ˜23 ms, which is ˜4% of our previous result.

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    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.

  14. Megavolt, Multigigawatt Pulsed Plasma Switch

    NASA Technical Reports Server (NTRS)

    Lee, Ja H.; Choi, Sang H.; Song, Kyo D.

    1996-01-01

    Plasma switch proposed for use in high-voltage, high-current pulse power system. Designed not only to out-perform conventional spark-gap switch but also relatively compact and lightweight. Features inverse-pinch configuration to prevent constriction of current sheets into filaments, plus multiple-ring-electrode structure to resist high-voltage breakdown.

  15. Battery switch for downhole tools

    DOEpatents

    Boling, Brian E.

    2010-02-23

    An electrical circuit for a downhole tool may include a battery, a load electrically connected to the battery, and at least one switch electrically connected in series with the battery and to the load. The at least one switch may be configured to close when a tool temperature exceeds a selected temperature.

  16. Improved switch-resistor packaging

    NASA Technical Reports Server (NTRS)

    Redmerski, R. E.

    1980-01-01

    Packaging approach makes resistors more accessible and easily identified with specific switches. Failures are repaired more quickly because of improved accessibility. Typical board includes one resistor that acts as circuit breaker, and others are positioned so that their values can be easily measured when switch is operated. Approach saves weight by using less wire and saves valuable panel space.

  17. Task Switching: A PDP Model

    ERIC Educational Resources Information Center

    Gilbert, Sam J.; Shallice, Tim

    2002-01-01

    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…

  18. Component Processes in Task Switching.

    ERIC Educational Resources Information Center

    Meiran, Nachshon; Chorev, Ziv; Sapir, Ayelet

    2000-01-01

    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…

  19. Optical Fibre Switch

    NASA Astrophysics Data System (ADS)

    Markatos, S.; Ayres, S.; Kreit, D.; Kerr, A.; Youngquist, R. C.; Giles, I. P.

    1987-10-01

    The design construction and operation of a thermally controlled optical fibre switch, based upon the lap/polish technique, is described in this paper. The lap/polish method allows access to the evanescent field in an optical fibre and coupling between two fibres can be controlled from zero to total power transfer by changing the refractive index of the oil in the coupling region. Such refractive index changes can be induced thermally by directly heating the matching oil at the interaction area, with forming heating elements close to the fibre core. Power coupling is then proportional to the current supplied to the electrodes. Results are presented showing the frequency response of tlio device.

  20. FAST OPENING SWITCH

    DOEpatents

    Bender, M.; Bennett, F.K.; Kuckes, A.F.

    1963-09-17

    A fast-acting electric switch is described for rapidly opening a circuit carrying large amounts of electrical power. A thin, conducting foil bridges a gap in this circuit and means are provided for producing a magnetic field and eddy currents in the foil, whereby the foil is rapidly broken to open the circuit across the gap. Advantageously the foil has a hole forming two narrow portions in the foil and the means producing the magnetic field and eddy currents comprises an annular coil having its annulus coaxial with the hole in the foil and turns adjacent the narrow portions of the foil. An electrical current flows through the coil to produce the magnetic field and eddy currents in the foil. (AEC)

  1. "Smart" watchdog safety switch

    DOEpatents

    Kronberg, James W.

    1991-01-01

    A method and apparatus for monitoring a process having a periodic output so that the process equipment is not damaged in the event of a controller failure, comprising a low-pass and peak clipping filter, an event detector that generates an event pulse for each valid change in magnitude of the filtered periodic output, a timing pulse generator, a counter that increments upon receipt of any timing pulse and resets to zero on receipt of any event pulse, an alarm that alerts when the count reaches some preselected total count, and a set of relays that opens to stop power to process equipment. An interface module can be added to allow the switch to accept a variety of periodic output signals.

  2. Automatic thermal switch

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

  3. Optimized scalable network switch

    DOEpatents

    Blumrich, Matthias A.; Chen, Dong; Coteus, Paul W.

    2010-02-23

    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.

  4. Optimized scalable network switch

    DOEpatents

    Blumrich, Matthias A.; Chen, Dong; Coteus, Paul W.; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Steinmacher-Burow, Burkhard D.; Takken, Todd E.; Vranas, Pavlos M.

    2007-12-04

    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.

  5. ''Smart'' watchdog safety switch

    DOEpatents

    Kronberg, J.W.

    1991-10-01

    A method and apparatus for monitoring a process having a periodic output so that the process equipment is not damaged in the event of a controller failure, comprising a low-pass and peak clipping filter, an event detector that generates an event pulse for each valid change in magnitude of the filtered periodic output, a timing pulse generator, a counter that increments upon receipt of any timing pulse and resets to zero on receipt of any event pulse, an alarm that alerts when the count reaches some preselected total count, and a set of relays that opens to stop power to process equipment. An interface module can be added to allow the switch to accept a variety of periodic output signals. 21 figures.

  6. High-Voltage, High-Power Gaseous Electronics Switch For Electric Grid Power Conversion

    NASA Astrophysics Data System (ADS)

    Sommerer, Timothy J.

    2014-05-01

    We are developing a high-voltage, high-power gas switch for use in low-cost power conversion terminals on the electric power grid. Direct-current (dc) power transmission has many advantages over alternating current (ac) transmission, but at present the high cost of ac-dc power interconversion limits the use of dc. The gas switch we are developing conducts current through a magnetized cold cathode plasma in hydrogen or helium to reach practical current densities > 1 A/cm2. Thermal and sputter damage of the cathode by the incident ion flux is a major technical risk, and is being addressed through use of a ``self-healing'' liquid metal cathode (eg, gallium). Plasma conditions and cathode sputtering loss are estimated by analyzing plasma spectral emission. A particle-in-cell plasma model is used to understand various aspects of switch operation, including the conduction phase (where plasma densities can exceed 1013 cm-3), the switch-open phase (where the high-voltage must be held against gas breakdown on the left side of Paschen's curve), and the switching transitions (especially the opening process, which is initiated by forming an ion-matrix sheath adjacent to a control grid). The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000298.

  7. High genetic diversity declines towards the geographic range periphery of Adonis vernalis, a Eurasian dry grassland plant.

    PubMed

    Hirsch, H; Wagner, V; Danihelka, J; Ruprecht, E; Sánchez-Gómez, P; Seifert, M; Hensen, I

    2015-11-01

    Genetic diversity is important for species' fitness and evolutionary processes but our knowledge on how it varies across a species' distribution range is limited. The abundant centre hypothesis (ACH) predicts that populations become smaller and more isolated towards the geographic range periphery - a pattern that in turn should be associated with decreasing genetic diversity and increasing genetic differentiation. We tested this hypothesis in Adonis vernalis, a dry grassland plant with an extensive Eurasian distribution. Its life-history traits and distribution characteristics suggest a low genetic diversity that decreases and a high genetic differentiation that increases towards the range edge. We analysed AFLP fingerprints in 28 populations along a 4698-km transect from the geographic range core in Russia to the western range periphery in Central and Western Europe. Contrary to our expectation, our analysis revealed high genetic diversity (range of proportion of polymorphic bands = 56-81%, He = 0.168-0.238) and low genetic differentiation across populations (Φ(ST) = 0.18). However, in congruence with the genetic predictions of the ACH, genetic diversity decreased and genetic differentiation increased towards the range periphery. Spanish populations were genetically distinct, suggesting a divergent post-glacial history in this region. The high genetic diversity and low genetic differentiation in the remaining A. vernalis populations is surprising given the species' life-history traits and points to the possibility that the species has been widely distributed in the studied region or that it has migrated from a diverse source in an East-West direction, in the past. PMID:26122089

  8. Specially-Made Lipid-Based Assemblies for Improving Transmembrane Gene Delivery: Comparison of Basic Amino Acid Residue Rich Periphery.

    PubMed

    Jiang, Qian; Yue, Dong; Nie, Yu; Xu, Xianghui; He, Yiyan; Zhang, Shiyong; Wagner, Ernst; Gu, Zhongwei

    2016-06-01

    Cationic lipid based assemblies provide a promising platform for effective gene condensation into nanosized particles, and the peripheral properties of the assemblies are vital for complexation and interaction with physical barriers. Here, we report three cationic twin head lipids, and each of them contains a dioleoyl-glutamate hydrophobic tail and a twin polar head of lysine, arginine, or histidine. Such lipids were proven to self-assemble in aqueous solution with well-defined nanostructures and residual amino-, guanidine-, or imidazole-rich periphery, showing strong buffering capacity and good liquidity. The assemblies with arginine (RL) or lysine (KL) periphery exhibited positive charges (∼+35 mV) and complete condensation of pDNA into nanosized complexes (∼120 nm). In contrast, assemblies composed of histidine-rich lipids (HL) showed relatively low cationic electric potential (∼+10 mV) and poor DNA binding ability. As expected, the designed RL assemblies with guanidine-rich periphery enhanced the in vitro gene transfection up to 190-fold as compared with the golden standard PEI25k and Lipofectamine 2000, especially in the presence of serum. Meanwhile, interaction with cell and endo/lysosome membrane also revealed the superiority of RL complexes, that the guanidine-rich surface efficiently promoted transmembrane process in cellular internalization and endosomal disruption. More importantly, RL complexes also succeeded beyond others in vivo with significantly (∼7-fold) enhanced expression in HepG2 tumor xenografts in mice, as well as stronger green fluorescence protein imaging in isolated tumors and tumor frozen sections. PMID:27097286

  9. High genetic diversity declines towards the geographic range periphery of Adonis vernalis, a Eurasian dry grassland plant.

    PubMed

    Hirsch, H; Wagner, V; Danihelka, J; Ruprecht, E; Sánchez-Gómez, P; Seifert, M; Hensen, I

    2015-11-01

    Genetic diversity is important for species' fitness and evolutionary processes but our knowledge on how it varies across a species' distribution range is limited. The abundant centre hypothesis (ACH) predicts that populations become smaller and more isolated towards the geographic range periphery - a pattern that in turn should be associated with decreasing genetic diversity and increasing genetic differentiation. We tested this hypothesis in Adonis vernalis, a dry grassland plant with an extensive Eurasian distribution. Its life-history traits and distribution characteristics suggest a low genetic diversity that decreases and a high genetic differentiation that increases towards the range edge. We analysed AFLP fingerprints in 28 populations along a 4698-km transect from the geographic range core in Russia to the western range periphery in Central and Western Europe. Contrary to our expectation, our analysis revealed high genetic diversity (range of proportion of polymorphic bands = 56-81%, He = 0.168-0.238) and low genetic differentiation across populations (Φ(ST) = 0.18). However, in congruence with the genetic predictions of the ACH, genetic diversity decreased and genetic differentiation increased towards the range periphery. Spanish populations were genetically distinct, suggesting a divergent post-glacial history in this region. The high genetic diversity and low genetic differentiation in the remaining A. vernalis populations is surprising given the species' life-history traits and points to the possibility that the species has been widely distributed in the studied region or that it has migrated from a diverse source in an East-West direction, in the past.

  10. Multi-frequency forced oscillation technique using impulse oscillations: can it give mechanical information about the lung periphery?

    PubMed

    Hamakawa, Hiroshi; Sakai, Hiroaki; Takahashi, Ayuko; Bando, Toru; Date, Hiroshi

    2013-01-01

    Forced oscillation techniques (FOTs) using sine curved oscillatory waves are used for assessing the lung periphery, but measure only overall respiratory mechanics. Therefore, mathematical models of the respiratory system serve as vehicles to obtain detailed mechanics. Although the simplest model of respiratory mechanics is a simple 3-element series (RIC) model, the constant phase (CP) model is recently used for characterizing respiratory mechanics, which has the advantage of partitioning of respiratory mechanics into airway and tissue components. Meanwhile, FOTs using non-sine curved oscillatory waves are easily applied in patients with severe respiratory diseases because they do not require voluntary apnea. If the latter type of FOTs is as informative as the former, the question arises whether a FOT using non-sine curved oscillatory waves (IOS) could be used to study mechanical properties of the lung periphery. And the CP model should fit the impedance spectra. To answer this, subjects with lymphangioleiomyomatosis (LAM) were recruited as a cohort of patients with lung parenchymal disease. Impedance spectra obtained by the IOS were fitted to the CP and RIC models. Mean values of goodness of fit from the CP and RIC models were 0.978 ± 0.022 and 0.968 ± 0.026, respectively. The extra sum-of-squares F test was used to compare the two mathematical models. The F ratio was 2.37 ± 1.40 and the p-value was 0.29 ± 0.21. Unfortunately, there was no compelling evidence for adopting the CP model for the evaluation of impedance spectra obtained by IOS. This result might relate to the uncertainty of IOS for detecting mechanical properties of the lung periphery.

  11. Agricultural Activities of a Meadow Eliminated Plant Litter from the Periphery of a Farmland in Inner Mongolia, China

    PubMed Central

    Kawada, Kiyokazu; Borjigin, Wuyunna; Nakamura, Toru

    2015-01-01

    The purpose of our investigation was to clarify the effects of agriculture on the process of loss of litter at the periphery of a farmland. This study revealed the generation process of an ecologically unusual phenomenon that is observed around cropland in semi-arid regions. We hypothesized that the vegetation around a farmland cannot supply plant litter to the ground surface because the ecological structure has been changed by agricultural activities. The study was conducted at Xilingol steppe, Xilingol League, Inner Mongolia Autonomous Region, China. Four study lines were established from the edge of an arable field to the surrounding meadow and parallel to the wind direction during the strong wind season. Key measurement for each line was set at the border between the farmland and steppe. Four study sites were set at intervals along each line. Plant litter, soil particle size distribution, plant species composition, plant volume, and species diversity were investigated. Despite using the same mowing method at the meadows of all study sites, the litter at the only periphery of the farmland completely disappeared. Soil particle size distribution in steppe, which was adjacent to the farmland, was similar to that of the farmland. Plant community structure at the periphery of the farmland was different from that of the far side from the farmland. This implies that soil scattered from the farmland affected the species composition of the steppe. Consequently, the change in plant community structure induced litter loss because of mowing. We concluded that plant litter was lost near the farmland because of the combined effects of farming and mowing. The results support our hypothesis that the vegetation around a farmland cannot supply plant litter because the ecological structure has been changed by agricultural activities. PMID:26241943

  12. Affective modulation of attentional switching.

    PubMed

    Heerebout, Bram T; Todorović, Ana; Smedinga, Hilde E; Phaf, R Hans

    2013-01-01

    Affective modulation of attentional switching may have developed early in evolution and may therefore have primacy over other affective influences. This behavioral study investigated the influence of affect on attentional switching between emotionally neutral stimuli, whether limited-capacity control processes are involved, and whether attentional flexibility should be distinguished from attentional broadening. Experiment 1 showed that suboptimally presented happy faces facilitated switching from an automatized response routine, whereas angry faces had the opposite effect. In Experiment 2, participants with a dominant global (i.e., broad) or local (i.e., narrow) spatial bias switched more easily to the opposite bias after suboptimal happy faces than after neutral primes but less easily after angry faces. Affective modulation of attentional switching was probably incorporated during evolution in many more complex forms of information processing.

  13. 49 CFR 236.6 - Hand-operated switch equipped with switch circuit controller.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Hand-operated switch equipped with switch circuit..., AND APPLIANCES Rules and Instructions: All Systems General § 236.6 Hand-operated switch equipped with switch circuit controller. Hand-operated switch equipped with switch circuit controller connected to...

  14. 49 CFR 236.6 - Hand-operated switch equipped with switch circuit controller.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Hand-operated switch equipped with switch circuit..., AND APPLIANCES Rules and Instructions: All Systems General § 236.6 Hand-operated switch equipped with switch circuit controller. Hand-operated switch equipped with switch circuit controller connected to...

  15. 49 CFR 236.6 - Hand-operated switch equipped with switch circuit controller.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Hand-operated switch equipped with switch circuit..., AND APPLIANCES Rules and Instructions: All Systems General § 236.6 Hand-operated switch equipped with switch circuit controller. Hand-operated switch equipped with switch circuit controller connected to...

  16. 49 CFR 236.6 - Hand-operated switch equipped with switch circuit controller.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Hand-operated switch equipped with switch circuit..., AND APPLIANCES Rules and Instructions: All Systems General § 236.6 Hand-operated switch equipped with switch circuit controller. Hand-operated switch equipped with switch circuit controller connected to...

  17. 49 CFR 236.6 - Hand-operated switch equipped with switch circuit controller.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Hand-operated switch equipped with switch circuit..., AND APPLIANCES Rules and Instructions: All Systems General § 236.6 Hand-operated switch equipped with switch circuit controller. Hand-operated switch equipped with switch circuit controller connected to...

  18. RHIC spin flipper AC dipole controller

    SciTech Connect

    Oddo, P.; Bai, M.; Dawson, C.; Gassner, D.; Harvey, M.; Hayes, T.; Mernick, K.; Minty, M.; Roser, T.; Severino, F.; Smith, K.

    2011-03-28

    The RHIC Spin Flipper's five high-Q AC dipoles which are driven by a swept frequency waveform require precise control of phase and amplitude during the sweep. This control is achieved using FPGA based feedback controllers. Multiple feedback loops are used to and dynamically tune the magnets. The current implementation and results will be presented. Work on a new spin flipper for RHIC (Relativistic Heavy Ion Collider) incorporating multiple dynamically tuned high-Q AC-dipoles has been developed for RHIC spin-physics experiments. A spin flipper is needed to cancel systematic errors by reversing the spin direction of the two colliding beams multiple times during a store. The spin flipper system consists of four DC-dipole magnets (spin rotators) and five AC-dipole magnets. Multiple AC-dipoles are needed to localize the driven coherent betatron oscillation inside the spin flipper. Operationally the AC-dipoles form two swept frequency bumps that minimize the effect of the AC-dipole dipoles outside of the spin flipper. Both AC bumps operate at the same frequency, but are phase shifted from each other. The AC-dipoles therefore require precise control over amplitude and phase making the implementation of the AC-dipole controller the central challenge.

  19. Experimental evidence of impingement induced strains at the interface and the periphery of an embedded acetabular cup implant.

    PubMed

    Arndt, Christoph; Voigt, Christian; Steinke, Hanno; Salis-Soglio, Georg V; Scholz, Roger

    2012-01-01

    After total hip arthroplasty, impingement of implant components may occur during every-day patient activities causing increased shear stresses at the acetabular implant-bone interface. In the literature, impingement related lever-out moments were noted for a number of acetabular components. But there is little information about pelvic load transfer. The aim of the current study was to measure the three-dimensional strain distribution at the macrostructured hemispherical interface and in the periphery of a standard acetabular press-fit cup in an experimental implant-bone substitute model. An experimental setup was developed to simulate impingement loading via a lever arm representing the femoral component and the lower limb. In one experimental setup 12 strain gauges were embedded at predefined positions in the periphery of the acetabular cup implant inside a tray, using polyurethane composite resin as a bone substitute material. By incremental rotation of the implant tray in steps of 10 and 30 deg, respectively, the strains were measured at evenly distributed positions. With the described method 288 genuine strain values were measured in the periphery of an embedded acetabular cup implant in one experimental setup. In two additional setups the strains were evaluated at different distances from the implant interface. Both in radial and meridional interface directions strain magnitudes reach their peak near the rim of the cup below the impingement site. Values of equatorial strains vary near zero and reach their peaks near the rim of the cup on either side and in some distance from the impingement site. Interestingly, the maximum of averaged radial strains does not occur, as expected, close to the interface but at an interface offset of 5.6 mm. With the described experimental setup it is now possible to measure and display the three-dimensional strain distribution in the interface and the periphery of an embedded acetabular cup implant. The current study provides the

  20. Switching Phenomena in a System with No Switches

    NASA Astrophysics Data System (ADS)

    Preis, Tobias; Stanley, H. Eugene

    2010-02-01

    It is widely believed that switching phenomena require switches, but this is actually not true. For an intriguing variety of switching phenomena in nature, the underlying complex system abruptly changes from one state to another in a highly discontinuous fashion. For example, financial market fluctuations are characterized by many abrupt switchings creating increasing trends ("bubble formation") and decreasing trends ("financial collapse"). Such switching occurs on time scales ranging from macroscopic bubbles persisting for hundreds of days to microscopic bubbles persisting only for a few seconds. We analyze a database containing 13,991,275 German DAX Future transactions recorded with a time resolution of 10 msec. For comparison, a database providing 2,592,531 of all S&P500 daily closing prices is used. We ask whether these ubiquitous switching phenomena have quantifiable features independent of the time horizon studied. We find striking scale-free behavior of the volatility after each switching occurs. We interpret our findings as being consistent with time-dependent collective behavior of financial market participants. We test the possible universality of our result by performing a parallel analysis of fluctuations in transaction volume and time intervals between trades. We show that these financial market switching processes have properties similar to those of phase transitions. We suggest that the well-known catastrophic bubbles that occur on large time scales—such as the most recent financial crisis—are no outliers but single dramatic representatives caused by the switching between upward and downward trends on time scales varying over nine orders of magnitude from very large (≈102 days) down to very small (≈10 ms).

  1. Channelized coplanar waveguide pin-diode switches

    NASA Technical Reports Server (NTRS)

    Ponchak, G. E.; Simons, R. N.

    1989-01-01

    Three different types of p-i-n diode, reflective CPW switches are presented. The first two switches are the series and the shunt mounted diode switches. Each has achieved greater than 15 dB of isolation over a broad bandwidth. The third switch is a narrow band, high isolation switched filter which has achieved 19 dB of isolation. Equivalent circuits and measured performance for each switch is presented.

  2. Alarm toe switch. [Patent application

    DOEpatents

    Ganyard, F.P.

    1980-11-18

    An alarm toe switch inserted within a shoe for energizing an alarm circuit in 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.

  3. Scanning electron microscopy as a tool for the analysis of colony architecture produced by phenotypic switching of a human pathogenic yeast Candida tropicalis

    NASA Astrophysics Data System (ADS)

    Furlaneto, M. C.; Andrade, C. G. T. J.; Aragão, P. H. A.; França, E. J. G.; Moralez, A. T. P.; Ferreira, L. C. S.

    2012-07-01

    Candida tropicalis has been identified as one of the most prevalent pathogenic yeast species of the Candida-non-albicans group. Phenotypic switching is a biological phenomenon related to the occurrence of spontaneous emergence of colonies with different morphologies that provides variability within colonizing populations in order to adapt to different environments. Currently, studies of the microstructure of switching variant colonies are not subject of extensive research. SEM analysis was used to verify the architecture of whole Candida colonies. The strain 49/07 exhibited a hemispherical shape character, while the strain 335/07 showed a volcano shape with mycelated-edge colony. The ring switch variant is characterized by a highly wrinkled centre and an irregular periphery. The rough phenotype exhibited a three-dimensional architecture and was characterized by the presence of deep central and peripheral depressions areas. The ultrastructural analysis also allowed the observation of the arrangement of individual cells within the colonies. The whole smooth colony consisted entirely of yeast cells. Differently, aerial filaments were found all around the colony periphery of the volcano shape colony. For this colony type the mycelated-edge consisted mainly of hyphae, although yeast cells are also seen. The ring and rough colonies phenotypes comprised mainly yeast cells with the presence of extracellular material connecting neighbouring cells. This study has shown that SEM can be used effectively to examine the microarchitecture of colonies morphotypes of the yeast C. tropicalis and further our understanding of switching event in this pathogen.

  4. Prosthetic Avian Vocal Organ Controlled by a Freely Behaving Bird Based on a Low Dimensional Model of the Biomechanical Periphery

    PubMed Central

    Arneodo, Ezequiel M.; Perl, Yonatan Sanz; Goller, Franz; Mindlin, Gabriel B.

    2012-01-01

    Because of the parallels found with human language production and acquisition, birdsong is an ideal animal model to study general mechanisms underlying complex, learned motor behavior. The rich and diverse vocalizations of songbirds emerge as a result of the interaction between a pattern generator in the brain and a highly nontrivial nonlinear periphery. Much of the complexity of this vocal behavior has been understood by studying the physics of the avian vocal organ, particularly the syrinx. A mathematical model describing the complex periphery as a nonlinear dynamical system leads to the conclusion that nontrivial behavior emerges even when the organ is commanded by simple motor instructions: smooth paths in a low dimensional parameter space. An analysis of the model provides insight into which parameters are responsible for generating a rich variety of diverse vocalizations, and what the physiological meaning of these parameters is. By recording the physiological motor instructions elicited by a spontaneously singing muted bird and computing the model on a Digital Signal Processor in real-time, we produce realistic synthetic vocalizations that replace the bird's own auditory feedback. In this way, we build a bio-prosthetic avian vocal organ driven by a freely behaving bird via its physiologically coded motor commands. Since it is based on a low-dimensional nonlinear mathematical model of the peripheral effector, the emulation of the motor behavior requires light computation, in such a way that our bio-prosthetic device can be implemented on a portable platform. PMID:22761555

  5. A molecular network for the transport of the TI-VAMP/VAMP7 vesicles from cell center to periphery.

    PubMed

    Burgo, Andrea; Proux-Gillardeaux, Véronique; Sotirakis, Emmanuel; Bun, Philippe; Casano, Alessandra; Verraes, Agathe; Liem, Ronald K H; Formstecher, Etienne; Coppey-Moisan, Maïté; Galli, Thierry

    2012-07-17

    The compartmental organization of eukaryotic cells is maintained dynamically by vesicular trafficking. SNARE proteins play a crucial role in intracellular membrane fusion and need to be targeted to their proper donor or acceptor membrane. The molecular mechanisms that allow for the secretory vesicles carrying the v-SNARE TI-VAMP/VAMP7 to leave the cell center, load onto microtubules, and reach the periphery to mediate exocytosis are largely unknown. Here, we show that the TI-VAMP/VAMP7 partner Varp, a Rab21 guanine nucleotide exchange factor, interacts with GolginA4 and the kinesin 1 Kif5A. Activated Rab21-GTP in turn binds to MACF1, an actin and microtubule regulator, which is itself a partner of GolginA4. These components are required for directed movement of TI-VAMP/VAMP7 vesicles from the cell center to the cell periphery. The molecular mechanisms uncovered here suggest an integrated view of the transport of vesicles carrying a specific v-SNARE toward the cell surface.

  6. Prosthetic avian vocal organ controlled by a freely behaving bird based on a low dimensional model of the biomechanical periphery.

    PubMed

    Arneodo, Ezequiel M; Perl, Yonatan Sanz; Goller, Franz; Mindlin, Gabriel B

    2012-01-01

    Because of the parallels found with human language production and acquisition, birdsong is an ideal animal model to study general mechanisms underlying complex, learned motor behavior. The rich and diverse vocalizations of songbirds emerge as a result of the interaction between a pattern generator in the brain and a highly nontrivial nonlinear periphery. Much of the complexity of this vocal behavior has been understood by studying the physics of the avian vocal organ, particularly the syrinx. A mathematical model describing the complex periphery as a nonlinear dynamical system leads to the conclusion that nontrivial behavior emerges even when the organ is commanded by simple motor instructions: smooth paths in a low dimensional parameter space. An analysis of the model provides insight into which parameters are responsible for generating a rich variety of diverse vocalizations, and what the physiological meaning of these parameters is. By recording the physiological motor instructions elicited by a spontaneously singing muted bird and computing the model on a Digital Signal Processor in real-time, we produce realistic synthetic vocalizations that replace the bird's own auditory feedback. In this way, we build a bio-prosthetic avian vocal organ driven by a freely behaving bird via its physiologically coded motor commands. Since it is based on a low-dimensional nonlinear mathematical model of the peripheral effector, the emulation of the motor behavior requires light computation, in such a way that our bio-prosthetic device can be implemented on a portable platform. PMID:22761555

  7. Direct Space Vector PWM Strategy for Matrix Converters with Reduced Number of Switching Transitions

    NASA Astrophysics Data System (ADS)

    Tadano, Yugo; Hamada, Shizunori; Urushibata, Shota; Nomura, Masakatsu; Sato, Yukihiko; Ishida, Muneaki

    This paper proposes a novel “Direct Space Vector PWM (Direct SVPWM)” strategy based on the direct AC/AC conversion approach for three-phase to three-phase matrix converters. This method allows the sine input and sine output waveforms as a major premise, and gives top priority to the improvement of the output control performance in motor drive applications, for instance, provides maximum riding comfort for an elevator, etc. Output voltage harmonics, switching losses, and common-mode voltage can be reduced across the entire voltage region. In addition, the switching count can be reduced even further by fully utilizing the output current detection value. Direct space vectors are first defined, and the selection method of space vectors is described. Next, the PWM duty calculation technique is explained. Finally, the validity of the proposed method is proven from the comparison with the conventional virtual indirect method based on the experimental and analysis results.

  8. Regenerative switching CMOS system

    DOEpatents

    Welch, James D.

    1998-01-01

    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.

  9. Low impedance switch

    DOEpatents

    Hornig, Donald F.

    1976-01-01

    1. A low inductance switch comprising a pair of spaced apart, annularly shaped, plate members of conducting material supported in substantially parallel, insulated relationship, said plate members being provided with a plurality of radially extending, spoke-like extensions whereby said members may be connected into a plurality of electrical circuits, and an electrical discharge means connected across said spaced plate members for effecting the simultaneous closing of the electrical circuits connected thereto, said electrical discharge means including an elongated, sealed envelope which contains an ionizable gas and which is supported on one of said plate members with the major axis of said envelope extending generally perpendicular to the plane of said plate members, a pair of elongated, spaced apart, insulated electrodes supported within said envelope and extending axially thereof, one of said electrodes being connected to each of said plate members, and a third, firing or trigger electrode supported within said envelope intermediate said main electrodes and being insulated from said main electrodes.

  10. Regenerative switching CMOS system

    DOEpatents

    Welch, J.D.

    1998-06-02

    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.

  11. The magnetoelectrochemical switch

    PubMed Central

    Lunca Popa, Petru; Kemp, Neil T.; Majjad, Hicham; Dalmas, Guillaume; Faramarzi, Vina; Andreas, Christian; Hertel, Riccardo; Doudin, Bernard

    2014-01-01

    In the field of spintronics, the archetype solid-state two-terminal device is the spin valve, where the resistance is controlled by the magnetization configuration. We show here how this concept of spin-dependent switch can be extended to magnetic electrodes in solution, by magnetic control of their chemical environment. Appropriate nanoscale design allows a huge enhancement of the magnetic force field experienced by paramagnetic molecular species in solutions, which changes between repulsive and attractive on changing the electrodes’ magnetic orientations. Specifically, the field gradient force created within a sub-100-nm-sized nanogap separating two magnetic electrodes can be reversed by changing the orientation of the electrodes’ magnetization relative to the current flowing between the electrodes. This can result in a breaking or making of an electric nanocontact, with a change of resistance by a factor of up to 103. The results reveal how an external field can impact chemical equilibrium in the vicinity of nanoscale magnetic circuits. PMID:25009179

  12. Electrically switched ion exchange

    SciTech Connect

    Lilga, M.A.; Schwartz, D.T.; Genders, D.

    1997-10-01

    A variety of waste types containing radioactive {sup 137}Cs are found throughout the DOE complex. These waste types include water in reactor cooling basins, radioactive high-level waste (HLW) in underground storage tanks, and groundwater. Safety and regulatory requirements and economics require the removal of radiocesium before these wastes can be permanently disposed of. Electrically Switched Ion Exchange (ESIX) is an approach for radioactive cesium separation that combines IX and electrochemistry to provide a selective, reversible, and economic separation method that also produces little or no secondary waste. In the ESIX process, an electroactive IX film is deposited electrochemically onto a high-surface area electrode, and ion uptake and elution are controlled directly by modulating the potential of the film. For cesium, the electroactive films under investigation are ferrocyanides, which are well known to have high selectivities for cesium in concentrated sodium solutions. When a cathode potential is applied to the film, Fe{sup +3} is reduced to the Fe{sup +2} state, and a cation must be intercalated into the film to maintain charge neutrality (i.e., Cs{sup +} is loaded). Conversely, if an anodic potential is applied, a cation must be released from the film (i.e., Cs{sup +} is unloaded). Therefore, to load the film with cesium, the film is simply reduced; to unload cesium, the film is oxidized.

  13. Utility-Interconnected Photovoltaic Systems: Evaluating the Rationale for the Utility-Accessible External Disconnect Switch

    SciTech Connect

    Coddington, M.; Margolis, R.M.; Aabakken, J.

    2008-01-01

    The utility-accessible alternating current (AC) external disconnect switch (EDS) for distributed generators, including photovoltaic (PV) systems, is a hardware feature that allows a utility?s employees to manually disconnect a customer-owned generator from the electricity grid. This paper examines the utility-accessible EDS debate in the context of utility-interactive PV systems for residential and small commercial installations. It also evaluates the rationale for EDS requirements.

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

    ERIC Educational Resources Information Center

    Schneider, Darryl W.; Logan, Gordon D.

    2007-01-01

    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…

  15. Polariton condensates: Electrical spin switching

    NASA Astrophysics Data System (ADS)

    Liew, T. C. H.

    2016-10-01

    Ultra-low-power electronic switching of stable exciton-polariton spin states has now been achieved in a semiconductor microcavity. This opens a new route to the integration of spin-based photonics and electronics.

  16. Wide Bandgap Extrinsic Photoconductive Switches

    SciTech Connect

    Sullivan, James S.

    2012-01-20

    Photoconductive semiconductor switches (PCSS) have been investigated since the late 1970s. Some devices have been developed that withstand tens of kilovolts and others that switch hundreds of amperes. However, no single device has been developed that can reliably withstand both high voltage and switch high current. Yet, photoconductive switches still hold the promise of reliable high voltage and high current operation with subnanosecond risetimes. Particularly since good quality, bulk, single crystal, wide bandgap semiconductor materials have recently become available. In this chapter we will review the basic operation of PCSS devices, status of PCSS devices and properties of the wide bandgap semiconductors 4H-SiC, 6H-SiC and 2H-GaN.

  17. Electron collisions in gas switches

    SciTech Connect

    Christophorou, L.G.

    1989-01-01

    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.

  18. Workshop on Repetitive Opening Switches

    NASA Astrophysics Data System (ADS)

    Kristiansen, M.; Schoenbach, K. H.

    1981-04-01

    A workshop on Repetitive Opening Switches was conducted by Texas Tech University for the U.S. Army Research Office. Several papers on a wide range of innovative opening switch concepts were presented. Discussions about the research needs to advance the state-of-the-art in this important, emerging field are summarized. A concensus on research topics and their importance is summarized and a suggested research priority list given.

  19. A Piezoelectric Cryogenic Heat Switch

    NASA Technical Reports Server (NTRS)

    Jahromi, Amir E.; Sullivan, Dan F.

    2014-01-01

    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 greater than 100 were achieved when the positioner applied its maximum force of 8 N. We discuss the advantages of using this system in cryogenic applications, and estimate the ultimate performance of an optimized PZHS.

  20. High PRF high current switch

    DOEpatents

    Moran, Stuart L.; Hutcherson, R. Kenneth

    1990-03-27

    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.

  1. High-Speed Fiber Switches

    NASA Astrophysics Data System (ADS)

    Margulis, Walter; Tarasenko, Oleksandr; Yu, Zhangwei; Fonjallaz, Pierre-Yves; Knape, Harald

    2008-10-01

    All-fiber optical switches based on fiber with electrodes exhibit transition times <10 ns. The devices are monolithic and robust, they are simple and could potentially be manufactured at low cost. The insertion loss is extremely low and the devices are compatible with single mode fiber technology. Two types of switches are discussed, one based on polarization rotation, the other one relying on the wavelength shift of a fiber Bragg grating (FBG).

  2. K-Band Latching Switches

    NASA Technical Reports Server (NTRS)

    Piotrowski, W. S.; Raue, J. E.

    1984-01-01

    Design, development, and tests are described for two single-pole-double-throw latching waveguide ferrite switches: a K-band switch in WR-42 waveguide and a Ka-band switch in WR-28 waveguide. Both switches have structurally simple junctions, mechanically interlocked without the use of bonding materials; they are impervious to the effects of thermal, shock, and vibration stresses. Ferrite material for the Ka-band switch with a proper combination of magnetic and dielectric properties was available and resulted in excellent low loss, wideband performance. The high power handling requirement of the K-band switch limited the choice of ferrite to nickel-zinc compositions with adequate magnetic properties, but with too low relative dielectric constant. The relative dielectric constant determines the junction dimensions for given frequency responses. In this case the too low value unavoidably leads to a larger than optimum junction volume, increasing the insertion loss and restricting the operating bandwidth. Efforts to overcome the materials-related difficulties through the design of a composite junction with increased effective dielectric properties efforts to modify the relative dielectric constant of nickel-zinc ferrite are examined.

  3. Vanadium dioxide phase change switches

    NASA Astrophysics Data System (ADS)

    Field, M.; Hillman, C.; Stupar, P.; Hacker, J.; Griffith, Z.; Lee, K.-J.

    2015-05-01

    The thermally driven metal insulator transition in vanadium dioxide (VO2) is used to create a low loss millimeter wave switch which operates up to and beyond W-band frequencies. We have built RF switches using vanadium dioxide thin films fabricated within a section of inverted transmission line with integrated on chip heaters to provide local thermal control. On heating the films above the metal insulator transition we obtain record low switch insertion loss of 0.13 dB at 50 GHz and 0.5 dB at 110 GHz. The switch cut-off frequency is high, fc ~ 45 THz, due to the low on state resistance and off state capacitance. We have investigated the device physics of these switches including self-latching of the devices under high RF powers, and demonstrated their integration with silicon germanium RF circuits where the switch heater current sources and control logic are also integrated into the same silicon germanium circuit.

  4. Working Memory Costs of Task Switching

    ERIC Educational Resources Information Center

    Liefooghe, Baptist; Barrouillet, Pierre; Vandierendonck, Andre; Camos, Valerie

    2008-01-01

    Although many accounts of task switching emphasize the importance of working memory as a substantial source of the switch cost, there is a lack of evidence demonstrating that task switching actually places additional demands on working memory. The present study addressed this issue by implementing task switching in continuous complex span tasks…

  5. Coupling an induction motor type generator to ac power lines. [making windmill generators compatible with public power lines

    NASA Technical Reports Server (NTRS)

    Nola, F. J. (Inventor)

    1984-01-01

    A system for coupling an induction motor type generator to an A.C. power line includes an electronic switch means that is controlled by a control system and is regulated to turn on at a relatively late point in each half cycle of its operation. The energizing power supplied by the line to the induction motor type generator is decreased and the net power delivered to the line is increased.

  6. Electronic logic for enhanced switch reliability

    DOEpatents

    Cooper, J.A.

    1984-01-20

    A logic circuit is used to enhance redundant switch reliability. Two or more switches are monitored for logical high or low output. The output for the logic circuit produces a redundant and fail-safe representation of the switch outputs. When both switch outputs are high, the output is high. Similarly, when both switch outputs are low, the logic circuit's output is low. When the output states of the two switches do not agree, the circuit resolves the conflict by memorizing the last output state which both switches were simultaneously in and produces the logical complement of this output state. Thus, the logic circuit of the present invention allows the redundant switches to be treated as if they were in parallel when the switches are open and as if they were in series when the switches are closed. A failsafe system having maximum reliability is thereby produced.

  7. 49 CFR 218.103 - Hand-operated switches, including crossover switches.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Hand-operated switches, including crossover... Equipment, Switches, and Fixed Derails § 218.103 Hand-operated switches, including crossover switches. (a)(1...) General. Employees operating or verifying the position of a hand-operated switch shall: (1) Conduct...

  8. 49 CFR 218.103 - Hand-operated switches, including crossover switches.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Hand-operated switches, including crossover... Equipment, Switches, and Fixed Derails § 218.103 Hand-operated switches, including crossover switches. (a)(1...) General. Employees operating or verifying the position of a hand-operated switch shall: (1) Conduct...

  9. 49 CFR 218.103 - Hand-operated switches, including crossover switches.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Hand-operated switches, including crossover... Equipment, Switches, and Fixed Derails § 218.103 Hand-operated switches, including crossover switches. (a)(1...) General. Employees operating or verifying the position of a hand-operated switch shall: (1) Conduct...

  10. 49 CFR 218.103 - Hand-operated switches, including crossover switches.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Hand-operated switches, including crossover... Equipment, Switches, and Fixed Derails § 218.103 Hand-operated switches, including crossover switches. (a)(1...) General. Employees operating or verifying the position of a hand-operated switch shall: (1) Conduct...

  11. Superconductor coil geometry and ac losses

    NASA Technical Reports Server (NTRS)

    Pierce, T. V., Jr.; Zapata, R. N.

    1976-01-01

    An empirical relation is presented which allows simple computation of volume-averaged winding fields from central fields for coils of small rectangular cross sections. This relation suggests that, in certain applications, ac-loss minimization can be accomplished by use of low winding densities, provided that hysteresis losses are independent of winding density. The ac-loss measurements on coils wound of twisted multifilamentary composite superconductors show no significant dependence on ac losses on winding density, thus permitting the use of winding density as an independent design parameter in loss minimization.

  12. Plasma flow switch experiment on Procyon

    SciTech Connect

    Benage, J.F. Jr.; Bowers, R.; Peterson, D.

    1995-09-01

    This report presents the results obtained from a series of plasma flow switch experiments done on the Procyon explosive pulse power generator. These experiments involved switching into a fixed inductance dummy load and also into a dynamic implosion load. The results indicated that the switch did fairly well at switching current into the load, but the results for the implosion are more ambiguous. The results are compared to calculations and the implications for future plasma flow switch work are discussed.

  13. Plasma flow switch experiment on Procyon

    NASA Astrophysics Data System (ADS)

    Benage, J. F., Jr.; Bowers, R.; Peterson, D.

    This report presents the results obtained from a series of plasma flow switch experiments done on the Procyon explosive pulse power generator. These experiments involved switching into a fixed inductance dummy load and also into a dynamic implosion load. The results indicated that the switch did fairly well at switching current into the load, but the results for the implosion are more ambiguous. The results are compared to calculations and the implications for future plasma flow switch work are discussed.

  14. Testing results for the HCT-1400 switch

    SciTech Connect

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

    1996-07-01

    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.

  15. Non-latching relay switch assembly

    DOEpatents

    Duimstra, Frederick A.

    1991-01-01

    A non-latching relay switch assembly which includes a coil section and a switch or contact section. The coil section includes a permanent magnet and an electromagnet. The respective sections are arranged in separate locations or cavities in the assembly. The switch has a "normal" position and is selectively switched by an overriding electromagnetic assembly. The switch returns to the "normal" position when the overriding electromagnetic assembly is inactive.

  16. Segregation of mass at the periphery of N -isopropylacrylamide-co-acrylic-acid microgels at high temperatures

    DOE PAGES

    Hyatt, John S.; Do, Changwoo; Hu, Xiaobo; Choi, Hong Sung; Kim, Jin Woong; Lyon, L. Andrew; Fernandez-Nieves, Alberto

    2015-09-29

    Here, we investigate poly(N-isopropylacrylamide) (pNIPAM) microgels randomly copolymerized with large mol % of protonated acrylic acid (AAc), finding that above the lower critical solution temperature the presence of the acid strongly disrupts pNIPAM's collapse, leading to unexpected new behavior at high temperatures. We see a dramatic increase in the ratio between the radius of gyration and the hydrodynamic radius above the theoretical value for homogeneous spheres, and a corresponding increase of the network length scale, which we attribute to the presence of a heterogeneous polymer distribution that forms due to frustration of pNIPAM's coil-to-globule transition by the AAc. Finally, wemore » analyze this phenomenon using a Debye-Bueche-like scattering contribution as opposed to the Lorentzian term often used, interpreting the results in terms of mass segregation at the particle periphery.« less

  17. Role of inflammation and apoptosis in multiple sclerosis: Comparative analysis between the periphery and the central nervous system.

    PubMed

    Macchi, Beatrice; Marino-Merlo, Francesca; Nocentini, Ugo; Pisani, Valerio; Cuzzocrea, Salvatore; Grelli, Sandro; Mastino, Antonio

    2015-10-15

    Multiple sclerosis (MS) is a complex, multifactorial disease associated with damage to the axonal myelin sheaths and neuronal degeneration. The pathognomonic event in MS is oligodendrocyte loss accompanied by axonal damage, blood-brain barrier leakage, inflammation and infiltration of immune cells. The etiopathogenesis of MS is far from being elucidated. However, increasing evidence suggests that the inflammatory and apoptotic responses, occurring in patients either at the peripheral level or the central nervous system (CNS), can play a role. In this review, we give a comprehensive picture of general aspects of inflammation and apoptosis in MS, with special emphasis on the until now not well highlighted possible links between phenomena relevant to these aspects occurring in either the periphery or in the CNS during MS. PMID:26439966

  18. High speed packet switching

    NASA Technical Reports Server (NTRS)

    1991-01-01

    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 research project is to use the results of the SBIR Phase 1 effort to develop a sound, expandable hardware and software router architecture capable of forwarding 25,000 packets per second through the router and passing 300 megabits per second on the router's internal busses. The work being delivered under this contract received its funding from three different sources: the SNIPE/RIG contract (Contract Number F30602-89-C-0014, CDRL Sequence Number A002), the SBIR contract, and Proteon. The SNIPE/RIG and SBIR contracts had many overlapping requirements, which allowed the research done under SNIPE/RIG to be applied to SBIR. Proteon funded all of the work to develop new router interfaces other than FDDI, in addition to funding the productization of the router itself. The router being delivered under SBIR will be a fully product-quality machine. The work done during this contract produced many significant findings and results, summarized here and explained in detail in later sections of this report. The SNIPE/RIG contract was completed. That contract had many overlapping requirements with the SBIR contract, and resulted in the successful demonstration and delivery of a high speed router. The development that took place during the SNIPE/RIG contract produced findings that included the choice of processor and an understanding of the issues surrounding inter processor communications in a multiprocessor environment. Many significant speed enhancements to the router software were made during that time. Under the SBIR contract (and with help from Proteon-funded work), it was found that a single processor router achieved a throughput significantly higher than originally anticipated. For this reason, a single processor router was

  19. Woodland dynamics at the northern range periphery: a challenge for protected area management in a changing world.

    PubMed

    Powell, Scott L; Hansen, Andrew J; Rodhouse, Thomas J; Garrett, Lisa K; Betancourt, Julio L; Dicus, Gordon H; Lonneker, Meghan K

    2013-01-01

    Managers of protected natural areas increasingly are confronted with novel ecological conditions and conflicting objectives to preserve the past while fostering resilience for an uncertain future. This dilemma may be pronounced at range peripheries where rates of change are accelerated and ongoing invasions often are perceived as threats to local ecosystems. We provide an example from City of Rocks National Reserve (CIRO) in southern Idaho, positioned at the northern range periphery of pinyon-juniper (P-J) woodland. Reserve managers are concerned about P-J woodland encroachment into adjacent sagebrush steppe, but the rates and biophysical variability of encroachment are not well documented and management options are not well understood. We quantified the rate and extent of woodland change between 1950 and 2009 based on a random sample of aerial photo interpretation plots distributed across biophysical gradients. Our study revealed that woodland cover remained at approximately 20% of the study area over the 59-year period. In the absence of disturbance, P-J woodlands exhibited the highest rate of increase among vegetation types at 0.37% yr(-1). Overall, late-successional P-J stands increased in area by over 100% through the process of densification (infilling). However, wildfires during the period resulted in a net decrease of woody evergreen vegetation, particularly among early and mid-successional P-J stands. Elevated wildfire risk associated with expanding novel annual grasslands and drought is likely to continue to be a fundamental driver of change in CIRO woodlands. Because P-J woodlands contribute to regional biodiversity and may contract at trailing edges with global warming, CIRO may become important to P-J woodland conservation in the future. Our study provides a widely applicable toolset for assessing woodland ecotone dynamics that can help managers reconcile the competing demands to maintain historical fidelity and contribute meaningfully to the U

  20. Low Surface Brightness Imaging of the Magellanic System: Imprints of Tidal Interactions between the Clouds in the Stellar Periphery

    NASA Astrophysics Data System (ADS)

    Besla, Gurtina; Martínez-Delgado, David; van der Marel, Roeland P.; Beletsky, Yuri; Seibert, Mark; Schlafly, Edward F.; Grebel, Eva K.; Neyer, Fabian

    2016-07-01

    We present deep optical images of the Large and Small Magellanic Clouds (LMC and SMC) using a low cost telephoto lens with a wide field of view to explore stellar substructure in the outskirts of the stellar disk of the LMC (<10° from the LMC center). These data have higher resolution than existing star count maps, and highlight the existence of stellar arcs and multiple spiral arms in the northern periphery, with no comparable counterparts in the south. We compare these data to detailed simulations of the LMC disk outskirts, following interactions with its low mass companion, the SMC. We consider interaction in isolation and with the inclusion of the Milky Way tidal field. The simulations are used to assess the origin of the northern structures, including also the low density stellar arc recently identified in the Dark Energy Survey data by Mackey et al. at ˜15°. We conclude that repeated close interactions with the SMC are primarily responsible for the asymmetric stellar structures seen in the periphery of the LMC. The orientation and density of these arcs can be used to constrain the LMC’s interaction history with and impact parameter of the SMC. More generally, we find that such asymmetric structures should be ubiquitous about pairs of dwarfs and can persist for 1-2 Gyr even after the secondary merges entirely with the primary. As such, the lack of a companion around a Magellanic Irregular does not disprove the hypothesis that their asymmetric structures are driven by dwarf-dwarf interactions.

  1. Woodland Dynamics at the Northern Range Periphery: A Challenge for Protected Area Management in a Changing World

    PubMed Central

    Powell, Scott L.; Hansen, Andrew J.; Rodhouse, Thomas J.; Garrett, Lisa K.; Betancourt, Julio L.; Dicus, Gordon H.; Lonneker, Meghan K.

    2013-01-01

    Managers of protected natural areas increasingly are confronted with novel ecological conditions and conflicting objectives to preserve the past while fostering resilience for an uncertain future. This dilemma may be pronounced at range peripheries where rates of change are accelerated and ongoing invasions often are perceived as threats to local ecosystems. We provide an example from City of Rocks National Reserve (CIRO) in southern Idaho, positioned at the northern range periphery of pinyon-juniper (P-J) woodland. Reserve managers are concerned about P-J woodland encroachment into adjacent sagebrush steppe, but the rates and biophysical variability of encroachment are not well documented and management options are not well understood. We quantified the rate and extent of woodland change between 1950 and 2009 based on a random sample of aerial photo interpretation plots distributed across biophysical gradients. Our study revealed that woodland cover remained at approximately 20% of the study area over the 59-year period. In the absence of disturbance, P-J woodlands exhibited the highest rate of increase among vegetation types at 0.37% yr−1. Overall, late-successional P-J stands increased in area by over 100% through the process of densification (infilling). However, wildfires during the period resulted in a net decrease of woody evergreen vegetation, particularly among early and mid-successional P-J stands. Elevated wildfire risk associated with expanding novel annual grasslands and drought is likely to continue to be a fundamental driver of change in CIRO woodlands. Because P-J woodlands contribute to regional biodiversity and may contract at trailing edges with global warming, CIRO may become important to P-J woodland conservation in the future. Our study provides a widely applicable toolset for assessing woodland ecotone dynamics that can help managers reconcile the competing demands to maintain historical fidelity and contribute meaningfully to the U

  2. Design studies for the Mead-Phoenix 500 kV AC transmission project

    SciTech Connect

    Thallam, R.S.; Lundquist, T.G.; Gerlach, D.W.; Atmuri, S.R.; Selin, D.A.

    1995-10-01

    The Mead-Phoenix 500 kV ac line is 243 miles long and runs parallel to the existing Mead-Liberty 345 kV line. This line is planned for 70% series and 70% shunt compensation; it also incorporates the first application of a 50 kV phase shifting transformer that enables a 1,300 MW transmission capacity. This paper presents the design studies that were undertaken in arriving at the equipment ratings and insulation levels that lead to the equipment specifications. The shunt reactor switching requirements utilizing MOV across the breaker, line switching with line connected arresters and the breaker transient recovery voltage are also dealt with in the paper.

  3. High School Teachers Win ACS Prizes

    NASA Astrophysics Data System (ADS)

    Editorial Staff, Jce

    2009-07-01

    William E. Snyder is the 2009 winner of the ACS Division of Chemical Education Central Region Award for Excellence in High School Teaching; Sally Mitchell is the winner of the 2009 James Bryant Conant Award in High School Chemistry Teaching.

  4. Tevatron optics measurements using an AC dipole

    SciTech Connect

    Miyamoto, R.; Kopp, S.E.; Jansson, A.; Syphers, M.J.; /Fermilab

    2007-06-01

    The AC dipole is a device to study beam optics of hadron synchrotrons. It can produce sustained large amplitude oscillations with virtually no emittance growth. A vertical AC dipole for the Tevatron is recently implemented and a maximum oscillation amplitude of 2{sigma} (4{sigma}) at 980 GeV (150 GeV) is achieved [1]. When such large oscillations are measured with the BPM system of the Tevatron (20 {micro}m resolution), not only linear but even nonlinear optics can be directly measured. This paper shows how to measure {beta} function using an AC dipole and the result is compared to the other measurement. The paper also shows a test to detect optics changes when small changes are made in the Tevatron. Since an AC dipole is nondestructive, it allows frequent measurements of the optics which is necessary for such an test.

  5. The AC-120: The advanced commercial transport

    NASA Technical Reports Server (NTRS)

    Duran, David; Griffin, Ernest; Mendoza, Saul; Nguyen, Son; Pickett, Tim; Noernberg, Clemm

    1993-01-01

    The main objective of this design was to fulfill a need for a new airplane to replace the aging 100 to 150 passenger, 1500 nautical mile range aircraft such as the Douglas DC9 and Boeing 737-100 airplanes. After researching the future aircraft market, conducting extensive trade studies, and analysis on different configurations, the AC-120 Advanced Commercial Transport final design was achieved. The AC-120's main design features include the incorporation of a three lifting surface configuration which is powered by two turboprop engines. The AC-120 is an economically sensitive aircraft which meets the new FM Stage Three noise requirements, and has lower NO(x) emissions than current turbofan powered airplanes. The AC-120 also improves on its contemporaries in passenger comfort, manufacturing, and operating cost.

  6. Wide Bandgap Extrinsic Photoconductive Switches

    NASA Astrophysics Data System (ADS)

    Sullivan, James Stephen

    Wide Bandgap Extrinsic Photoconductive Switches Semi-insulating Gallium Nitride, 4H and 6H Silicon Carbide are attractive materials for compact, high voltage, extrinsic, photoconductive switches due to their wide bandgap, high dark resistance, high critical electric field strength and high electron saturation velocity. These wide bandgap semiconductors are made semi-insulating by the addition of vanadium (4H and 6H-SiC) and iron (2H-GaN) impurities that form deep acceptors. These deep acceptors trap electrons donated from shallow donor impurities. The electrons can be optically excited from these deep acceptor levels into the conduction band to transition the wide bandgap semiconductor materials from a semi-insulating to a conducting state. Extrinsic photoconductive switches with opposing electrodes have been constructed using vanadium compensated 6H-SiC and iron compensated 2H-GaN. These extrinsic photoconductive switches were tested at high voltage and high power to determine if they could be successfully used as the closing switch in compact medical accelerators. The successful development of a vanadium compensated, 6H-SiC extrinsic photoconductive switch for use as a closing switch for compact accelerator applications was realized by improvements made to the vanadium, nitrogen and boron impurity densities. The changes made to the impurity densities were based on the physical intuition outlined and simple rate equation models. The final 6H-SiC impurity 'recipe' calls for vanadium, nitrogen and boron densities of 2.5 e17 cm-3, 1.25e17 cm-3 and ≤ 1e16 cm-3, respectively. This recipe was originally developed to maximize the quantum efficiency of the vanadium compensated 6H-SiC, while maintaining a thermally stable semi-insulating material. The rate equation models indicate that, besides increasing the quantum efficiency, the impurity recipe should be expected to also increase the carrier recombination time. Three generations of 6H-SiC materials were tested. The

  7. Photoresistance Switching of Plasmonic Nanopores

    PubMed Central

    2015-01-01

    Fast and reversible modulation of ion flow through nanosized apertures is important for many nanofluidic applications, including sensing and separation systems. Here, we present the first demonstration of a reversible plasmon-controlled nanofluidic valve. We show that plasmonic nanopores (solid-state nanopores integrated with metal nanocavities) can be used as a fluidic switch upon optical excitation. We systematically investigate the effects of laser illumination of single plasmonic nanopores and experimentally demonstrate photoresistance switching where fluidic transport and ion flow are switched on or off. This is manifested as a large (∼1–2 orders of magnitude) increase in the ionic nanopore resistance and an accompanying current rectification upon illumination at high laser powers (tens of milliwatts). At lower laser powers, the resistance decreases monotonically with increasing power, followed by an abrupt transition to high resistances at a certain threshold power. A similar rapid transition, although at a lower threshold power, is observed when the power is instead swept from high to low power. This hysteretic behavior is found to be dependent on the rate of the power sweep. The photoresistance switching effect is attributed to plasmon-induced formation and growth of nanobubbles that reversibly block the ionic current through the nanopore from one side of the membrane. This explanation is corroborated by finite-element simulations of a nanobubble in the nanopore that show the switching and the rectification. PMID:25514824

  8. Method and apparatus for pulse width modulation control of an AC induction motor

    DOEpatents

    Geppert, Steven; Slicker, James M.

    1984-01-01

    An inverter is connected between a source of DC power and a three-phase AC induction motor, and a micro-processor-based circuit controls the inverter using pulse width modulation techniques. In the disclosed method of pulse width modulation, both edges of each pulse of a carrier pulse train are equally modulated by a time proportional to sin .THETA., where .THETA. is the angular displacement of the pulse center at the motor stator frequency from a fixed reference point on the carrier waveform. The carrier waveform frequency is a multiple of the motor stator frequency. The modulated pulse train is then applied to each of the motor phase inputs with respective phase shifts of 120.degree. at the stator frequency. Switching control commands of electronic switches in the inverter are stored in a random access memory (RAM) and the locations of the RAM are successively read out in a cyclic manner, each bit of a given RAM location controlling a respective phase input of the motor. The DC power source preferably comprises rechargeable batteries and all but one of the electronic switches in the inverter can be disabled, the remaining electronic switch being part of a "flyback" DC-DC converter circuit for recharging the battery.

  9. Method and apparatus for pulse width modulation control of an AC induction motor

    NASA Technical Reports Server (NTRS)

    Geppert, Steven (Inventor); Slicker, James M. (Inventor)

    1984-01-01

    An inverter is connected between a source of DC power and a three-phase AC induction motor, and a micro-processor-based circuit controls the inverter using pulse width modulation techniques. In the disclosed method of pulse width modulation, both edges of each pulse of a carrier pulse train are equally modulated by a time proportional to sin .THETA., where .THETA. is the angular displacement of the pulse center at the motor stator frequency from a fixed reference point on the carrier waveform. The carrier waveform frequency is a multiple of the motor stator frequency. The modulated pulse train is then applied to each of the motor phase inputs with respective phase shifts of 120.degree. at the stator frequency. Switching control commands of electronic switches in the inverter are stored in a random access memory (RAM) and the locations of the RAM are successively read out in a cyclic manner, each bit of a given RAM location controlling a respective phase input of the motor. The DC power source preferably comprises rechargeable batteries and all but one of the electronic switches in the inverter can be disabled, the remaining electronic switch being part of a flyback DC-DC converter circuit for recharging the battery.

  10. HOLLOTRON switch for megawatt lightweight space inverters

    NASA Technical Reports Server (NTRS)

    Poeschel, R. L.; Goebel, D. M.; Schumacher, R. W.

    1991-01-01

    The feasibility of satisfying the switching requirements for a megawatt ultralight inverter system using HOLLOTRON switch technology was determined. The existing experimental switch hardware was modified to investigate a coaxial HOLLOTRON switch configuration and the results were compared with those obtained for a modified linear HOLLOTRON configuration. It was concluded that scaling the HOLLOTRON switch to the current and voltage specifications required for a megawatt converter system is indeed feasible using a modified linear configuration. The experimental HOLLOTRON switch operated at parameters comparable to the scaled coaxial HOLLOTRON. However, the linear HOLLOTRON data verified the capability for meeting all the design objectives simultaneously including current density (greater than 2 A/sq cm), voltage (5 kV), switching frequency (20 kHz), switching time (300 ns), and forward voltage drop (less than or equal to 20 V). Scaling relations were determined and a preliminary design was completed for an engineering model linear HOLLOTRON switch to meet the megawatt converter system specifications.

  11. Finite-time quantised feedback asynchronously switched control of sampled-data switched linear systems

    NASA Astrophysics Data System (ADS)

    Wang, Ronghao; Xing, Jianchun; Li, Juelong; Xiang, Zhengrong

    2016-10-01

    This paper studies the problem of stabilising a sampled-data switched linear system by quantised feedback asynchronously switched controllers. The idea of a quantised feedback asynchronously switched control strategy originates in earlier work reflecting actual system characteristic of switching and quantising, respectively. A quantised scheme is designed depending on switching time using dynamic quantiser. When sampling time, system switching time and controller switching time are all not uniform, the proposed switching controllers guarantee the system to be finite-time stable by a piecewise Lyapunov function and the average dwell-time method. Simulation examples are provided to show the effectiveness of the developed results.

  12. Optical Switch Using Risley Prisms

    DOEpatents

    Sweatt, William C.; Christenson, Todd R.

    2005-02-22

    An optical switch using Risley prisms and rotary microactuators to independently rotate the wedge prisms of each Risley prism pair is disclosed. The optical switch comprises an array of input Risley prism pairs that selectively redirect light beams from a plurality of input ports to an array of output Risley prism pairs that similarly direct the light beams to a plurality of output ports. Each wedge prism of each Risley prism pair can be independently rotated by a variable-reluctance stepping rotary microactuator that is fabricated by a multi-layer LIGA process. Each wedge prism can be formed integral to the annular rotor of the rotary microactuator by a DXRL process.

  13. Optical switch using Risley prisms

    SciTech Connect

    Sweatt, William C.; Christenson, Todd R.

    2003-04-15

    An optical switch using Risley prisms and rotary microactuators to independently rotate the wedge prisms of each Risley prism pair is disclosed. The optical switch comprises an array of input Risley prism pairs that selectively redirect light beams from a plurality of input ports to an array of output Risley prism pairs that similarly direct the light beams to a plurality of output ports. Each wedge prism of each Risley prism pair can be independently rotated by a variable-reluctance stepping rotary microactuator that is fabricated by a multi-layer LIGA process. Each wedge prism can be formed integral to the annular rotor of the rotary microactuator by a DXRL process.

  14. Switch Using Radio Frequency Identification

    NASA Technical Reports Server (NTRS)

    Fink, Patrick W. (Inventor); Lin, Gregory Y. (Inventor); Kennedy, Timothy F. (Inventor); Ngo, Phong H. (Inventor)

    2015-01-01

    Disclosed is an apparatus for use as a switch. In one embodiment, the switch comprises at least one RFID tag, each RFID tag comprising an antenna element and an RFID integrated circuit, at least one source element, and at least one lever arm. Each lever arm is connected to one of the RFID tags, and each lever arm is capable of two positions. One of the positions places the lever arm and the RFID tag connected thereto into alignment with the source element. Other embodiments are also described.

  15. Bumpless switching control for switched systems with partial actuator failures

    NASA Astrophysics Data System (ADS)

    Qi, Yiwen; Bao, Wen; Zhang, Qingxin; Chang, Juntao

    2016-11-01

    This study is concerned with the bumpless transfer problem for switched systems with partial actuator failures, in order to obtain smooth system performance output transition. Taking into account that the system requires a controller switching from current sub-controller to a fault-tolerant sub-controller after actuator fault. And bumpless transfer for control input cannot be traditionally designed when the actuator fault occurs, while performance smoothing can be considered and it is actually the ultimate goal of bumpless transfer. Specifically, the actuator fault model is firstly established and partial actuator fault is considered. Then, the system performance output signal is deemed as the main design variable of bumpless transfer, and closed-loop control systems both previous and after controller switching are constructed. Moreover, by using model matching thought and the adaptive sliding mode control technique, a bumpless transfer compensator design strategy is given to drive the performance output variable (after controller switching) to track the one of reference model. At last, simulation results of numeric and application examples demonstrate the effectiveness of the proposed bumpless transfer strategy.

  16. 78 FR 39345 - ACS Wireless, Inc.; Notice of Application

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-01

    ... COMMISSION ACS Wireless, Inc.; Notice of Application AGENCY: Securities and Exchange Commission (``Commission...''). Summary of Application: ACS Wireless, Inc. (``ACS Wireless'') seeks an order under section 3(b)(2) of the..., owning, holding or trading in securities. ACS Wireless is primarily engaged in providing...

  17. 21 CFR 888.1240 - AC-powered dynamometer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered dynamometer. 888.1240 Section 888.1240...) MEDICAL DEVICES ORTHOPEDIC DEVICES Diagnostic Devices § 888.1240 AC-powered dynamometer. (a) Identification. An AC-powered dynamometer is an AC-powered device intended for medical purposes to...

  18. 21 CFR 886.4440 - AC-powered magnet.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered magnet. 886.4440 Section 886.4440 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4440 AC-powered magnet. (a) Identification. An AC-powered magnet is an AC-powered device that generates a magnetic field intended to find and...

  19. 21 CFR 886.1630 - AC-powered photostimulator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered photostimulator. 886.1630 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1630 AC-powered photostimulator. (a) Identification. An AC-powered photostimulator is an AC-powered device intended to provide light stimulus...

  20. 21 CFR 886.1850 - AC-powered slitlamp biomicroscope.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered slitlamp biomicroscope. 886.1850... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1850 AC-powered slitlamp biomicroscope. (a) Identification. An AC-powered slitlamp biomicroscope is an AC-powered device that is...

  1. 21 CFR 886.4440 - AC-powered magnet.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false AC-powered magnet. 886.4440 Section 886.4440 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4440 AC-powered magnet. (a) Identification. An AC-powered magnet is an AC-powered device that generates a magnetic field intended to find and...

  2. 21 CFR 886.4440 - AC-powered magnet.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false AC-powered magnet. 886.4440 Section 886.4440 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4440 AC-powered magnet. (a) Identification. An AC-powered magnet is an AC-powered device that generates a magnetic field intended to find and...

  3. 21 CFR 886.4440 - AC-powered magnet.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false AC-powered magnet. 886.4440 Section 886.4440 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4440 AC-powered magnet. (a) Identification. An AC-powered magnet is an AC-powered device that generates a magnetic field intended to find and...

  4. 21 CFR 886.4440 - AC-powered magnet.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false AC-powered magnet. 886.4440 Section 886.4440 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4440 AC-powered magnet. (a) Identification. An AC-powered magnet is an AC-powered device that generates a magnetic field intended to find and...

  5. AC Electrokinetics of Physiological Fluids for Biomedical Applications.

    PubMed

    Lu, Yi; Liu, Tingting; Lamanda, Ariana C; Sin, Mandy L Y; Gau, Vincent; Liao, Joseph C; Wong, Pak Kin

    2015-12-01

    Alternating current (AC) electrokinetics is a collection of processes for manipulating bulk fluid mass and embedded objects with AC electric fields. The ability of AC electrokinetics to implement the major microfluidic operations, such as pumping, mixing, concentration, and separation, makes it possible to develop integrated systems for clinical diagnostics in nontraditional health care settings. The high conductivity of physiological fluids presents new challenges and opportunities for AC electrokinetics-based diagnostic systems. In this review, AC electrokinetic phenomena in conductive physiological fluids are described followed by a review of the basic microfluidic operations and the recent biomedical applications of AC electrokinetics. The future prospects of AC electrokinetics for clinical diagnostics are presented.

  6. Multiserver switch scheduling for high speed optical switches

    NASA Astrophysics Data System (ADS)

    Golla, Prasad; Blanton, John; Damm, Gerard

    2003-10-01

    A switch matrix implemented as an optical crossbar using semiconductor optical amplifiers is able to accommodate extreme concentrations of data traffic. Due to the need to reduce optical guard band overhead it is beneficial to switch fixed size bursts of data cells on a time slot basis. The high capacity of the optical matrix supports multiple optical ports per burst card, and the implementation of multiple queue servers per burst card helps make better use of the multiplicity of ports. Problems associated with arbitrating multiple ports and multiple servers per burst card have been resolved by extending the operation of existing iterative, single server scheduling algorithms. The multiserver arbitration time will be in proportion to the number of servers -- corresponding to the channels of DWDM link -- unless a reconciliation stage is used after each iteration when an arbiter per server is used. The reconciliation stage sets the problem of broken data dependencies between server arbitrations in this case. Further, to address the time limitations for computing the scheduling solution, parallel arbiter implementations have been developed and tested against single arbiter designs. Again, the broken dependencies between iterations of an arbitration are addressed through the use of a grant reconciliation stage. The use of multiple queue servers per burst card also resolves some of the data loss problems related to polarized traffic. Simulations of the multiple server and parallel arbiter implementations have demonstrated their efficiency compared to previous implementations. Compounded to this problem is maintaining high throughput of the switch matrix while observing data transit time limits. This involves balancing two contradictory requirements; switch or line card efficiency and data transit times. To improve efficiency it is desirable to transmit only full packets. However, to prevent loss of data due to timeout it will be necessary to transmit some incomplete

  7. Photoconductive Semiconductor Switches for pulsed power applications

    SciTech Connect

    Loubriel, G.M.; Zutavern, F.J.; Denison, G.J.; Helgeson, W.D.; McLaughlin, D.L.; O`Malley, M.W.; Buttram, M.T.

    1993-08-01

    Photoconductive Semiconductor Switches (PCSS) are being used in, or tested for, many different pulsed power applications as diverse as ultrawideband (UWB) transmitters and high current pulsers. Some aspects of the switches that are relevant to most of the applications are: switch lifetime (longevity), switch opening time (related to the lifetime of carriers in the semiconductor), switching jitter, and the required laser energy. This paper will emphasize the results that we have obtained with Si switches for UWB applications. These include: measurement of switch longevity (a total of 80 Coulombs or 40 C/cm for a 2 cm wide switch and 18.4 Coulombs or 73 Coulombs/cm for a 0.25 cm wide switch), switching at high repetition rates (up to 540 Hz), measurement of carrier lifetime decay rates (a fast one of a few {mu}s, and a slow one of about 330 {mu}s), and measurements on the effect of neutron irradiation on carrier lifetimes. The total charge switched seems to be the highest ever reported for a PCSS. We have used these Si switches in a variety of circuits to produce: a monocycle with a period of about 10 ns corresponding to a center frequency of about 84 MHz, and ringing (many pulse) waveforms with periods of about 1 ns and 7.5 ns corresponding to center frequencies of 770 MHz and 133 MHz. We will also discuss recent studies on the switching properties of GaP.

  8. In silico Analysis of 2085 Clones from a Normalized Rat Vestibular Periphery 3′ cDNA Library

    PubMed Central

    Roche, Joseph P.; Cioffi, Joseph A.; Kwitek, Anne E.; Erbe, Christy B.; Popper, Paul

    2005-01-01

    The inserts from 2400 cDNA clones isolated from a normalized Rattus norvegicus vestibular periphery cDNA library were sequenced and characterized. The Wackym-Soares vestibular 3′ cDNA library was constructed from the saccular and utricular maculae, the ampullae of all three semicircular canals and Scarpa's ganglia containing the somata of the primary afferent neurons, microdissected from 104 male and female rats. The inserts from 2400 randomly selected clones were sequenced from the 5′ end. Each sequence was analyzed using the BLAST algorithm compared to the Genbank nonredundant, rat genome, mouse genome and human genome databases to search for high homology alignments. Of the initial 2400 clones, 315 (13%) were found to be of poor quality and did not yield useful information, and therefore were eliminated from the analysis. Of the remaining 2085 sequences, 918 (44%) were found to represent 758 unique genes having useful annotations that were identified in databases within the public domain or in the published literature; these sequences were designated as known characterized sequences. 1141 sequences (55%) aligned with 1011 unique sequences had no useful annotations and were designated as known but uncharacterized sequences. Of the remaining 26 sequences (1%), 24 aligned with rat genomic sequences, but none matched previously described rat expressed sequence tags or mRNAs. No significant alignment to the rat or human genomic sequences could be found for the remaining 2 sequences. Of the 2085 sequences analyzed, 86% were singletons. The known, characterized sequences were analyzed with the FatiGO online data-mining tool (http://fatigo.bioinfo.cnio.es/) to identify level 5 biological process gene ontology (GO) terms for each alignment and to group alignments with similar or identical GO terms. Numerous genes were identified that have not been previously shown to be expressed in the vestibular system. Further characterization of the novel cDNA sequences may lead

  9. Deletion of AcMNPV ac146 eliminates the production of budded virus.

    PubMed

    Dickison, Virginia L; Willis, Leslie G; Sokal, Nadia R; Theilmann, David A

    Autographa californica multiple nucleopolyhedrovirus (AcMNPV) ac146 is a highly conserved gene in the Alpha- and Betabaculovirus genera that has an unknown function. Northern blot analysis and transcript mapping showed that ac146 is transcribed at late times post infection as a 1.2 kb mRNA. To determine the role of ac146 in the baculovirus life cycle ac146 knock out viruses were constructed. Transfection and plaque assays showed that all the ac146 deletions produced a single cell phenotype indicating that no infectious budded virus (BV) was produced, however occlusion bodies were formed. The lack of BV production was confirmed by viral titration utilizing both qPCR and TCID₅₀. Analysis of BV and occlusion derived virus (ODV) revealed that AC146 is associated with both forms of the virus and is modified specifically in ODV. This study therefore demonstrates that AC146 is a late virion associated protein and is essential for the viral life cycle.

  10. New internal multi-range resistors for ac voltage calibration by using TVC

    NASA Astrophysics Data System (ADS)

    Ali, Rasha S. M.

    2015-10-01

    Accurate calibration of ac voltages up to 1000 V by using thermal converters requires range resistors connected in series with the converter. The combination of a thermal converter and range resistor is known as the thermal voltage converter. In this paper, multi-range internal range resistors are designed and implemented in the National Institute for Standards (NIS), Egypt to cover the ac voltage ranges from 10 V to 750 V. The range resistor values are 2 kΩ, 10 kΩ, 20 kΩ, 40 kΩ, 100 kΩ, and 150 kΩ to cover the voltage ranges 10 V, 50 V, 100 V, 200 V, 500 V, and 750 V, respectively. The six range resistors are mounted in series with a single-junction thermo-element in the same box to provide a new thermal voltage converter. The required range resistor is selected by using a six-pin selector switch. Each resistor is connected to a selector pin. The new thermal voltage converter ranges are automatically calibrated against other standard thermal voltage converters at different frequencies by using a LabVIEW program to determine their ac-dc transfer difference at each range. The expanded uncertainties are estimated according to the GUM for all ranges at different frequencies. The performance of the new thermal voltage converter is also evaluated by comparing its ac-dc differences and its accuracy in measuring the ac voltage at different frequencies with a traditional thermal voltage converter.

  11. High voltage MOSFET switching circuit

    DOEpatents

    McEwan, T.E.

    1994-07-26

    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.

  12. High voltage MOSFET switching circuit

    DOEpatents

    McEwan, Thomas E.

    1994-01-01

    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.

  13. Anode initiated surface flashover switch

    DOEpatents

    Brainard, John P.; Koss, Robert J.

    2003-04-29

    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.

  14. Fast all-optical switch

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  15. Fast superconducting magnetic field switch

    SciTech Connect

    Goren, Y.; Mahale, N.K.

    1995-12-31

    The superconducting magnetic switch or fast kicker magnet is employed with an electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater than the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles. Magnetic switches and particularly fast kicker magnets are used in the accelerator industry to quickly deflect particle beams into and out of various transport lines, storage rings, dumps, and specifically to differentially route individual bunches of particles from a train of bunches which are injected or ejected from a given ring.

  16. Wide Bandgap Extrinsic Photoconductive Switches

    SciTech Connect

    Sullivan, James S.

    2013-07-03

    Semi-insulating Gallium Nitride, 4H and 6H Silicon Carbide are attractive materials for compact, high voltage, extrinsic, photoconductive switches due to their wide bandgap, high dark resistance, high critical electric field strength and high electron saturation velocity. These wide bandgap semiconductors are made semi-insulating by the addition of vanadium (4H and 6HSiC) and iron (2H-GaN) impurities that form deep acceptors. These deep acceptors trap electrons donated from shallow donor impurities. The electrons can be optically excited from these deep acceptor levels into the conduction band to transition the wide bandgap semiconductor materials from a semi-insulating to a conducting state. Extrinsic photoconductive switches with opposing electrodes have been constructed using vanadium compensated 6H-SiC and iron compensated 2H-GaN. These extrinsic photoconductive switches were tested at high voltage and high power to determine if they could be successfully used as the closing switch in compact medical accelerators.

  17. Optically-switched multiwavelength networks

    NASA Astrophysics Data System (ADS)

    Jeong, Gibong

    1997-05-01

    Optical networks are widely regarded as the ultimate solution to the bandwidth needs of future communication systems. With fiber-optic links deployed between nodes, the electronic devices at the switch nodes rather than the transmission medium, limit the bandwidth of a network. Instead, in an optically-switched network, a photonic switch can control connection paths without optical-to-electrical conversion of the signal, thereby avoiding speed and data-format restrictions imposed by such conversions. Despite the recognized potential of optically-switched multiwavelength networks, however, their overall effectiveness remains hampered by problems related to signal impairment such as noise, crosstalk and dispersion accumulating over a transparent path, and a finite number of wavelengths available limiting the network size. This dissertation analyzes the performance of optical networks at both the network and the device levels, and develops techniques to circumvent these problems. To begin with, we investigate the benefits of wavelength translation that has been claimed to be essential to best utilize a limited number of wavelengths in multiwavelength networks. A performance analysis shows that the network size and bandwidth are limited by dispersion, and spontaneous emission noise and crosstalk. First, we propose a technique to adaptively compensate bit skew caused by dispersion. In its basic form, the compensation method measures the skew using a pseudo- white training sequence and controls the read pointers of elastic buffers. The efficacy of this compensation technique is demonstrated for a WDM parallel data link. To better understand signal impairment, then we analyze and optimize the performance of photonic switches based on semiconductor optical amplifiers (SOA). SOAs have been used in photonic switches both to overcome loss and to serve as switchable crosspoints. Nonlinear noise figure optimization based on a steady-state analysis is followed by a dynamic model

  18. Cyclotron and linac production of Ac-225.

    PubMed

    Melville, Graeme; Allen, Barry J

    2009-04-01

    Radium needles that were once implanted into tumours as a cancer treatment are now obsolete and constitute a radioactive waste problem, as their half-life is 1600 years. The reduction of radium by photonuclear transmutation by bombarding Ra-226 with high-energy photons from a medical linear accelerator (linac) has been investigated. A linac dose of 2800 Gy produced about 2.4 MBq (64 microCi) of Ra-225, which decays to Ac-225 and can then be used for 'Targeted Alpha Therapy' (TAT) of cancer. This result, while consistent with theoretical calculations, is far too low to be of practical use unless much larger quantities of radium are irradiated. The increasing application of Ac-225 for cancer therapy indicates the potential need for its increased production and availability. This paper investigates the possibility of producing of Ac-225 in commercial quantities, which could potentially reduce obsolete radioactive material and displace the need for expensive importation of Ac-225 from the USA and Russia in the years ahead. Scaled up production of Ac-225 could theoretically be achieved by the use of a high current cyclotron or linac. Production specifications are determined for a linac in terms of current, pulse length and frequency, as well as an examination of other factors such as radiation issues and radionuclei separation. Yields are compared with those calculated for the Australian National Cyclotron in Sydney.

  19. Design and synthesis of 225Ac radioimmunopharmaceuticals.

    PubMed

    McDevitt, Michael R; Ma, Dangshe; Simon, Jim; Frank, R Keith; Scheinberg, David A

    2002-12-01

    The alpha-particle-emitting radionuclides 213Bi, 211At, 224Ra are under investigation for the treatment of leukemias, gliomas, and ankylosing spondylitis, respectively. 213Bi and 211At were attached to monoclonal antibodies and used as targeted immunotherapeutic agents while unconjugated 224Ra chloride selectively seeks bone. 225Ac possesses favorable physical properties for radioimmunotherapy (10d half-life and 4 net alpha particles), but has a history of unfavorable radiolabeling chemistry and poor metal-chelate stability. We selected functionalized derivatives of DOTA as the most promising to pursue from out of a group of potential 225Ac chelate compounds. A two-step synthetic process employing either MeO-DOTA-NCS or 2B-DOTA-NCS as the chelating moiety was developed to attach 225Ac to monoclonal antibodies. This method was tested using several different IgG systems. The chelation reaction yield in the first step was 93+/-8% radiochemically pure (n=26). The second step yielded 225Ac-DOTA-IgG constructs that were 95+/-5% radiochemically pure (n=27) and the mean percent immunoreactivity ranged from 25% to 81%, depending on the antibody used. This process has yielded several potential novel targeted 225Ac-labeled immunotherapeutic agents that may now be evaluated in appropriate model systems and ultimately in humans.

  20. Cosmic Shear - with ACS Pure Parallel Observations

    NASA Astrophysics Data System (ADS)

    Ratnatunga, Kavan

    2002-07-01

    The ACS, with greater sensitivity and sky coverage, will extend our ability to measure the weak gravitational lensing of galaxy images caused by the large scale distribution of dark matter. We propose to use the ACS in pure parallel {non- proprietary} mode, following the guidelines of the ACS Default Pure Parallel Program. Using the HST Medium Deep Survey WFPC2 database we have measured cosmic shear at arc-min angular scales. The MDS image parameters, in particular the galaxy orientations and axis ratios, are such that any residual corrections due to errors in the PSF or jitter are much smaller than the measured signal. This situation is in stark contrast with ground-based observations. We have also developed a statistical analysis procedure to derive unbiased estimates of cosmic shear from a large number of fields, each of which has a very small number of galaxies. We have therefore set the stage for measurements with the ACS at fainter apparent magnitudes and smaller, 10 arc-second scales corresponding to larger cosmological distances. We will adapt existing MDS WFPC2 maximum likelihood galaxy image analysis algorithms to work with the ACS. The analysis would also yield an online database similar to that in archive.stsci.edu/mds/

  1. Ultrafast Beam Switching Using Coupled VCSELs

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Goorjian, Peter

    2001-01-01

    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.

  2. Spark gap switch with spiral gas flow

    DOEpatents

    Brucker, John P.

    1989-01-01

    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.

  3. Hot electrons injection in carbon nanotubes under the influence of quasi-static ac-field

    NASA Astrophysics Data System (ADS)

    Amekpewu, M.; Mensah, S. Y.; Musah, R.; Mensah, N. G.; Abukari, S. S.; Dompreh, K. A.

    2016-07-01

    The theory of hot electrons injection in carbon nanotubes (CNTs) where both dc electric field (Ez), and a quasi-static ac field exist simultaneously (i.e. when the frequency ω of ac field is much less than the scattering frequency v (ω ≪ v or ωτ ≪ 1, v =τ-1) where τ is relaxation time) is studied. The investigation is done theoretically by solving semi-classical Boltzmann transport equation with and without the presence of the hot electrons source to derive the current densities. Plots of the normalized current density versus dc field (Ez) applied along the axis of the CNTs in the presence and absence of hot electrons reveal ohmic conductivity initially and finally negative differential conductivity (NDC) provided ωτ ≪ 1 (i.e. quasi- static case). With strong enough axial injection of the hot electrons, there is a switch from NDC to positive differential conductivity (PDC) about Ez ≥ 75 kV / cm and Ez ≥ 140 kV / cm for a zigzag CNT and an armchair CNT respectively. Thus, the most important tough problem for NDC region which is the space charge instabilities can be suppressed due to the switch from the NDC behaviour to the PDC behaviour predicting a potential generation of terahertz radiations whose applications are relevance in current-day technology, industry, and research.

  4. Broad and Largely Concordant Molecular Changes Characterize Tolerogenic and Immunogenic Dendritic Cell Maturation in Thymus and Periphery.

    PubMed

    Ardouin, Laurence; Luche, Hervé; Chelbi, Rabie; Carpentier, Sabrina; Shawket, Alaa; Montanana Sanchis, Frédéric; Santa Maria, Camille; Grenot, Pierre; Alexandre, Yannick; Grégoire, Claude; Fries, Anissa; Vu Manh, Thien-Phong; Tamoutounour, Samira; Crozat, Karine; Tomasello, Elena; Jorquera, Audrey; Fossum, Even; Bogen, Bjarne; Azukizawa, Hiroaki; Bajenoff, Marc; Henri, Sandrine; Dalod, Marc; Malissen, Bernard

    2016-08-16

    Dendritic cells (DCs) are instrumental in the initiation of T cell responses, but how thymic and peripheral tolerogenic DCs differ globally from Toll-like receptor (TLR)-induced immunogenic DCs remains unclear. Here, we show that thymic XCR1(+) DCs undergo a high rate of maturation, accompanied by profound gene-expression changes that are essential for central tolerance and also happen in germ-free mice. Those changes largely overlap those occurring during tolerogenic and, more unexpectedly, TLR-induced maturation of peripheral XCR1(+) DCs, arguing against the commonly held view that tolerogenic DCs undergo incomplete maturation. Interferon-stimulated gene (ISG) expression was among the few discriminators of immunogenic and tolerogenic XCR1(+) DCs. Tolerogenic XCR1(+) thymic DCs were, however, unique in expressing ISGs known to restrain virus replication. Therefore, a broad functional convergence characterizes tolerogenic and immunogenic XCR1(+) DC maturation in the thymus and periphery, maximizing antigen presentation and signal delivery to developing and to conventional and regulatory mature T cells. PMID:27533013

  5. Perceptual learning of Gabor orientation identification in visual periphery: complete inter-ocular transfer of learning mechanisms.

    PubMed

    Lu, Zhong-Lin; Chu, Wilson; Dosher, Barbara Anne; Lee, Sophia

    2005-09-01

    We combined the external noise paradigm, the Perceptual Template Model approach, and transfer tests to investigate the mechanisms and eye-specificity of perceptual learning of Gabor orientation in visual periphery. Coupled with a fixation task, discriminating a 5 from an S in a rapid small character string at fixation, contrast thresholds were estimated for each of eight external noise levels at two performance criteria using 3/1 and 2/1 staircases. Perceptual learning in one eye was measured over 10 practice sessions, followed by five sessions of practice in the new eye to assess transfer. We found that monocular learning improved performance (reduced contrast thresholds) with virtually equal magnitude across a wide range of external noise levels with no significant change in central task performance. Based on measurements of learning effects at two performance criterion levels, we identified a mixture of stimulus enhancement and external noise exclusion as the mechanism of perceptual learning underlying the observed improvements. Perceptual learning in the trained eye generalized completely to the untrained eye. We related the transfer patterns to known physiology and psychophysics on orientation direction coding.

  6. Specific nuclear envelope transmembrane proteins can promote the location of chromosomes to and from the nuclear periphery

    PubMed Central

    2013-01-01

    Background Different cell types have distinctive patterns of chromosome positioning in the nucleus. Although ectopic affinity-tethering of specific loci can be used to relocate chromosomes to the nuclear periphery, endogenous nuclear envelope proteins that control such a mechanism in mammalian cells have yet to be widely identified. Results To search for such proteins, 23 nuclear envelope transmembrane proteins were screened for their ability to promote peripheral localization of human chromosomes in HT1080 fibroblasts. Five of these proteins had strong effects on chromosome 5, but individual proteins affected different subsets of chromosomes. The repositioning effects were reversible and the proteins with effects all exhibited highly tissue-restricted patterns of expression. Depletion of two nuclear envelope transmembrane proteins that were preferentially expressed in liver each reduced the normal peripheral positioning of chromosome 5 in liver cells. Conclusions The discovery of nuclear envelope transmembrane proteins that can modulate chromosome position and have restricted patterns of expression may enable dissection of the functional relevance of tissue-specific patterns of radial chromosome positioning. PMID:23414781

  7. RNA11 protein is associated with the yeast spliceosome and is localized in the periphery of the cell nucleus.

    PubMed Central

    Chang, T H; Clark, M W; Lustig, A J; Cusick, M E; Abelson, J

    1988-01-01

    The yeast rna mutations (rna2 through rna10/11) are a set of temperature-sensitive mutations that result in the accumulation of pre-mRNAs at the nonpermissive temperature. Most of the yeast RNA gene products are involved in and essential for mRNA splicing in vitro, suggesting that they code for components of the splicing machinery. We tested this proposal by using an in vitro-synthesized RNA11 protein to complement the temperature-sensitive defect of the rna11 extract. During the in vitro complementation, the input RNA11 protein was associated with the 40S spliceosome and a 30S complex, suggesting that the RNA11 protein is indeed a component of the spliceosome. The formation of the RNA11-associated 30S complex did not require any exogenous RNA substrate, suggesting that this 30S particle is likely to be a preassembled complex involved in splicing. The RNA11-specific antibody inhibited the mRNA splicing in vitro, confirming the essential role of the RNA11 protein in mRNA splicing. Finally, using the anti-RNA11 antibody, we localized the RNA11 protein to the periphery of the yeast nucleus. Images PMID:3043176

  8. The crossover from collective motion to periphery diffusion for two-dimensional adatom-islands on Cu(111).

    PubMed

    Karim, Altaf; Kara, Abdelkader; Trushin, Oleg; Rahman, Talat S

    2011-11-23

    The diffusion of two-dimensional adatom-islands (up to 100 atoms) on Cu(111) has been studied, using the self-learning kinetic Monte Carlo method (Trushin et al 2005 Phys. Rev. B 72 115401). A variety of multiple- and single-atom processes are revealed in the simulations, and the size dependences of the diffusion coefficients and effective diffusion barriers are calculated for each. From the tabulated frequencies of events found in the simulation, we show a crossover from diffusion due to the collective motion of the island to a regime in which the island diffuses through periphery-dominated mass transport. This crossover occurs for island sizes between 13 and 19 atoms. For islands containing 19-100 atoms the scaling exponent is 1.5, which is in good agreement with previous work. The diffusion of islands containing 2-13 atoms can be explained primarily on the basis of a linear increase of the barrier for the collective motion with the size of the island.

  9. Galvanic stimulation of the vestibular periphery in guinea pigs during passive whole body rotation and self-generated head movement

    PubMed Central

    Lim, K.; Dye, J.; King, W. M.

    2012-01-01

    Irregular vestibular afferents exhibit significant phase leads with respect to angular velocity of the head in space. This characteristic and their connectivity with vestibulospinal neurons suggest a functionally important role for these afferents in producing the vestibulo-collic reflex (VCR). A goal of these experiments was to test this hypothesis with the use of weak galvanic stimulation of the vestibular periphery (GVS) to selectively activate or suppress irregular afferents during passive whole body rotation of guinea pigs that could freely move their heads. Both inhibitory and excitatory GVS had significant effects on compensatory head movements during sinusoidal and transient whole body rotations. Unexpectedly, GVS also strongly affected the vestibulo-ocular reflex (VOR) during passive whole body rotation. The effect of GVS on the VOR was comparable in light and darkness and whether the head was restrained or unrestrained. Significantly, there was no effect of GVS on compensatory eye and head movements during volitional head motion, a confirmation of our previous study that demonstrated the extravestibular nature of anticipatory eye movements that compensate for voluntary head movements. PMID:22262827

  10. [Sandfly fauna (Diptera: Psychodidae) in a focus of American cutaneous leishmaniasis on the urban periphery of Manaus, State of Amazonas].

    PubMed

    Barbosa, Maria das Graças Vale; Fé, Nelson Ferreira; Marcião, Alexandre Herculano Ribera; Silva, Ana Paula Thome; Monteiro, Wuelton Marcelo; Guerra, Jorge Augusto de Oliveira

    2008-01-01

    From August 2001 to July 2002, sand flies were collected from the bases of trees and, using CDC and Disney traps, from areas surrounding homes and forested areas in the São João community, on the urban periphery of Manaus, State of Amazonas. 4,104 specimens belonging to four subtribes, 13 genera and 49 species of the Phlebotominae subfamily were collected. The subtribe Psychodopygina predominated, with 3,403 (83%) specimens, especially of Nyssomyia umbratilis, Nyssomyia anduzei, Trichophoromyia eurypyga, Bichromomyia olmeca nociva and Bichromomyia flaviscutellata. The occurrences of Nyssomyia umbratilis and Nyssomyia anduzei, which have been incriminated as vectors for Leishmania (Viannia) guyanensis, and of Bichromomyia flaviscutellata and Bichromomyia olmeca nociva, for Leishmania (Leishmania) amazonensis, indicate that there is a risk of infection for people living in this area. Most (98.5%) of the sand flies were caught in the forested area. Nyssomyia anduzei and Bichromomyia olmeca nociva were collected from areas surrounding homes. The richness of vector species for Leishmania in this area shows the need for constant entomological surveillance.

  11. Speed discrimination in the far monocular periphery: A relative advantage for interocular comparisons consistent with self-motion

    PubMed Central

    Greer, Devon A.; Bonnen, Kathryn; Huk, Alexander C.; Cormack, Lawrence K.

    2016-01-01

    Some animals with lateral eyes (such as bees) control their navigation through the 3D world using velocity differences between the two eyes. Other animals with frontal eyes (such as primates, including humans) can perceive 3D motion based on the different velocities that a moving object projects upon the two retinae. Although one type of 3D motion perception involves a comparison between velocities from vastly different (monocular) portions of the visual field, and the other involves a comparison within overlapping (binocular) portions of the visual field, both compare velocities across the two eyes. Here we asked whether human interocular velocity comparisons, typically studied in the context of binocularly overlapping vision, operate in the far lateral (and hence, monocular) periphery and, if so, whether these comparisons were accordant with conventional interocular motion processing. We found that speed discrimination was indeed better between the two eyes' monocular visual fields, as compared to within a single eye's (monocular) visual field, but only when the velocities were consistent with commonly encountered motion. This intriguing finding suggests that mechanisms sensitive to relative motion information on opposite sides of an animal may have been retained, or at some point independently achieved, as the eyes became frontal in some animals. PMID:27548085

  12. Speed discrimination in the far monocular periphery: A relative advantage for interocular comparisons consistent with self-motion.

    PubMed

    Greer, Devon A; Bonnen, Kathryn; Huk, Alexander C; Cormack, Lawrence K

    2016-08-01

    Some animals with lateral eyes (such as bees) control their navigation through the 3D world using velocity differences between the two eyes. Other animals with frontal eyes (such as primates, including humans) can perceive 3D motion based on the different velocities that a moving object projects upon the two retinae. Although one type of 3D motion perception involves a comparison between velocities from vastly different (monocular) portions of the visual field, and the other involves a comparison within overlapping (binocular) portions of the visual field, both compare velocities across the two eyes. Here we asked whether human interocular velocity comparisons, typically studied in the context of binocularly overlapping vision, operate in the far lateral (and hence, monocular) periphery and, if so, whether these comparisons were accordant with conventional interocular motion processing. We found that speed discrimination was indeed better between the two eyes' monocular visual fields, as compared to within a single eye's (monocular) visual field, but only when the velocities were consistent with commonly encountered motion. This intriguing finding suggests that mechanisms sensitive to relative motion information on opposite sides of an animal may have been retained, or at some point independently achieved, as the eyes became frontal in some animals. PMID:27548085

  13. 46 CFR 112.43-1 - Switches.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Switches. 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 emergency lighting system must not have a switch,...

  14. 46 CFR 112.43-1 - Switches.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Switches. 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 emergency lighting system must not have a switch,...

  15. 46 CFR 112.43-1 - Switches.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Switches. 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 emergency lighting system must not have a switch,...

  16. 46 CFR 112.43-1 - Switches.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Switches. 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 emergency lighting system must not have a switch,...

  17. 46 CFR 112.43-1 - Switches.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Switches. 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 emergency lighting system must not have a switch,...

  18. RF switch positioner for communications satellite network

    NASA Technical Reports Server (NTRS)

    Storaasli, A. G.; Griesser, H. P.; Grant, R. W.

    1986-01-01

    The RF switch positioner is a simple, lightweight, redundant positioning mechanism used to reconfigure the antenna beam on the INTELSAT VI satellite. It simultaneously rotates approximately 100 squareax waveguide switches through a full 360 deg. The RF switch positioner has been space qualified and has performed to expectations in conjunction with the feed networks in range testing.

  19. Switch for serial or parallel communication networks

    DOEpatents

    Crosette, Dario B.

    1994-01-01

    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.

  20. Photoconductive switching for high power microwave generation

    SciTech Connect

    Pocha, M.D.; Hofer, W.W.

    1990-10-01

    Photoconductive switching is a technology that is being increasingly applied to generation of high power microwaves. Two primary semiconductors used for these devices are silicon and gallium arsenide. Diamond is a promising future candidate material. This paper discusses the important material parameters and switching modes, critical issues for microwave generation, and future directions for this high power, photoconductive switching technology.

  1. Bilingual Control: Sequential Memory in Language Switching

    ERIC Educational Resources Information Center

    Declerck, Mathieu; Philipp, Andrea M.; Koch, Iring

    2013-01-01

    To investigate bilingual language control, prior language switching studies presented visual objects, which had to be named in different languages, typically indicated by a visual cue. The present study examined language switching of predictable responses by introducing a novel sequence-based language switching paradigm. In 4 experiments,…

  2. A CW Gunn Diode Switching Element.

    ERIC Educational Resources Information Center

    Hurtado, Marco; Rosenbaum, Fred J.

    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…

  3. 14 CFR 25.1145 - Ignition switches.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Powerplant Controls and Accessories § 25.1145 Ignition switches. (a) Ignition switches must control each engine ignition circuit on each engine. (b) There must be means to quickly shut off all ignition by the grouping of switches or by a master ignition control....

  4. 49 CFR 213.135 - Switches.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... closed positions to allow wheels to pass the switch point. Lateral and vertical movement of a stock rail...) Each switch shall be maintained so that the outer edge of the wheel tread cannot contact the gage side... the lock or keeper in place. (g) Each switch position indicator shall be clearly visible at all...

  5. 49 CFR 213.135 - Switches.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... closed positions to allow wheels to pass the switch point. Lateral and vertical movement of a stock rail...) Each switch shall be maintained so that the outer edge of the wheel tread cannot contact the gage side... the lock or keeper in place. (g) Each switch position indicator shall be clearly visible at all...

  6. 49 CFR 213.135 - Switches.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... closed positions to allow wheels to pass the switch point. Lateral and vertical movement of a stock rail...) Each switch shall be maintained so that the outer edge of the wheel tread cannot contact the gage side... the lock or keeper in place. (g) Each switch position indicator shall be clearly visible at all...

  7. 49 CFR 213.135 - Switches.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... closed positions to allow wheels to pass the switch point. Lateral and vertical movement of a stock rail...) Each switch shall be maintained so that the outer edge of the wheel tread cannot contact the gage side... the lock or keeper in place. (g) Each switch position indicator shall be clearly visible at all...

  8. 49 CFR 213.135 - Switches.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... closed positions to allow wheels to pass the switch point. Lateral and vertical movement of a stock rail...) Each switch shall be maintained so that the outer edge of the wheel tread cannot contact the gage side... the lock or keeper in place. (g) Each switch position indicator shall be clearly visible at all...

  9. Switch Detection in Preschoolers' Cognitive Flexibility

    ERIC Educational Resources Information Center

    Chevalier, Nicolas; Wiebe, Sandra A.; Huber, Kristina L.; Espy, Kimberly Andrews

    2011-01-01

    The current study addressed the role of switch detection in cognitive flexibility by testing the effect of transition cues (i.e., cues that directly signal the need to switch or maintain a given task goal) in a cued set-shifting paradigm at 5 years of age. Children performed better, especially on switch trials, when transition cues were combined…

  10. 49 CFR 236.822 - Switch, spring.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Switch, spring. A switch equipped with a spring device which forces the points to their original position after being trailed through and holds them under spring compression. ... 49 Transportation 4 2014-10-01 2014-10-01 false Switch, spring. 236.822 Section...

  11. 49 CFR 236.822 - Switch, spring.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Switch, spring. A switch equipped with a spring device which forces the points to their original position after being trailed through and holds them under spring compression. ... 49 Transportation 4 2010-10-01 2010-10-01 false Switch, spring. 236.822 Section...

  12. 49 CFR 236.822 - Switch, spring.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Switch, spring. A switch equipped with a spring device which forces the points to their original position after being trailed through and holds them under spring compression. ... 49 Transportation 4 2011-10-01 2011-10-01 false Switch, spring. 236.822 Section...

  13. 49 CFR 236.822 - Switch, spring.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Switch, spring. A switch equipped with a spring device which forces the points to their original position after being trailed through and holds them under spring compression. ... 49 Transportation 4 2013-10-01 2013-10-01 false Switch, spring. 236.822 Section...

  14. 49 CFR 236.822 - Switch, spring.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Switch, spring. A switch equipped with a spring device which forces the points to their original position after being trailed through and holds them under spring compression. ... 49 Transportation 4 2012-10-01 2012-10-01 false Switch, spring. 236.822 Section...

  15. A new very high voltage semiconductor switch

    NASA Technical Reports Server (NTRS)

    Sundberg, G. R.

    1985-01-01

    A new family of semiconductor switches using double injection techniques and compensated deep impurities is described. They have the potential to raise switching voltages a factor of 10 higher (up to 100 kV) than p-n junction devices while exhibiting extremely low (or zero) forward voltage. Several potential power switching applications are indicated.

  16. A gain-coefficient switched Alexandrite laser

    NASA Astrophysics Data System (ADS)

    Lee, Chris J.; van der Slot, Peter J. M.; Boller, Klaus-J.

    2013-01-01

    We report on a gain-coefficient switched Alexandrite laser. An electro-optic modulator is used to switch between high and low gain states by making use of the polarization dependent gain of Alexandrite. In gain-coefficient switched mode, the laser produces 85 ns pulses with a pulse energy of 240 mJ at a repetition rate of 5 Hz.

  17. A Bilingual Advantage in Task Switching

    ERIC Educational Resources Information Center

    Prior, Anat; MacWhinney, Brian

    2010-01-01

    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…

  18. 47 CFR 69.106 - Local switching.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Local switching. 69.106 Section 69.106... Computation of Charges § 69.106 Local switching. (a) Except as provided in § 69.118, charges that are... switching facilities for the provision of interstate or foreign services. (b) The per minute...

  19. Voluntary Task Switching: Chasing the Elusive Homunculus

    ERIC Educational Resources Information Center

    Arrington, Catherine M.; Logan, Gordon D.

    2005-01-01

    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…

  20. Switch for serial or parallel communication networks

    DOEpatents

    Crosette, D.B.

    1994-07-19

    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.

  1. ac propulsion system for an electric vehicle

    NASA Technical Reports Server (NTRS)

    Geppert, S.

    1980-01-01

    It is pointed out that dc drives will be the logical choice for current production electric vehicles (EV). However, by the mid-80's, there is a good chance that the price and reliability of suitable high-power semiconductors will allow for a competitive ac system. The driving force behind the ac approach is the induction motor, which has specific advantages relative to a dc shunt or series traction motor. These advantages would be an important factor in the case of a vehicle for which low maintenance characteristics are of primary importance. A description of an EV ac propulsion system is provided, taking into account the logic controller, the inverter, the motor, and a two-speed transmission-differential-axle assembly. The main barrier to the employment of the considered propulsion system in EV is not any technical problem, but inverter transistor cost.

  2. Atrial-caval shunting (ACS) after trauma.

    PubMed

    Kudsk, K A; Sheldon, G F; Lim, R C

    1982-02-01

    Since 1968 the atrial-caval shunt (ACS), along with inflow occlusion at the porta hepatis, has been used at San Francisco General Hospital in 18 trauma patients to control massive hemorrhage from the inferior vena cava, hepatic veins, or liver. Thirteen patients died from irreversible shock. Five patients survived their initial injuries; one of them died 45 days later from the complications of shock and sepsis. No patients survived who sustained blunt trauma and were admitted in cardiac arrest. Only one of ten patients with BP less than 70 mm Hg after resuscitation survived, whereas four of eight with BP greater than 70 mm Hg survived. ACS was used to control caval injuries in seven patients (one survivor), severe hepatic parenchymal fractures in four patients (two survivors), and combined hepatic and caval injuries in seven patients (two survivors). Survivors had an average of 5.75 associated injuries; nonsurvivors had 3.8. No complications of ACS occurred in the surviving patients.

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

    ERIC Educational Resources Information Center

    Yim, Odilia; Bialystok, Ellen

    2012-01-01

    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…

  4. Investigation of edge- and bulk-related resistive switching behaviors and backward-scan effects in SiOx-based resistive switching memory

    NASA Astrophysics Data System (ADS)

    Chang, Yao-Feng; Ji, Li; Wang, Yanzhen; Chen, Pai-Yu; Zhou, Fei; Xue, Fei; Fowler, Burt; Yu, Edward T.; Lee, Jack C.

    2013-11-01

    Switching characteristics of edge and bulk device structures and an unusual backward-scan effect are investigated in SiOx-based resistive memory. Adding external resistance is found to dramatically affect reset voltage, providing insight into the unique unipolar operation. Non-edge, bulk SiOx-based devices allow flexibility in the fabrication process and hydrogen incorporation improves electroforming and device yield. A backward-scan phenomenon is examined by investigating the DC and AC pulse responses, which defines requirements for ON and OFF programming duration. Circuit-level simulation using a Verilog-A model aids device characterization and programming strategy development for future nonvolatile memory applications.

  5. Beneficial Effects of Adenylyl Cyclase Type 6 (AC6) Expression Persist Using a Catalytically Inactive AC6 Mutant

    PubMed Central

    Tang, Tong; Lai, Ngai Chin; Miyanohara, Atsushi; Guo, Tracy; Tang, Rouying; Firth, Amy L.; Yuan, Jason X.; Hammond, H. Kirk

    2011-01-01

    Cardiac-directed expression of AC6 has pronounced favorable effects on cardiac function possibly not linked with cAMP production. To determine rigorously whether cAMP generation is required for the beneficial effects of increased AC6 expression, we generated a catalytically inactive AC6 mutant (AC6mut) that has markedly diminished cAMP generating capacity by replacing aspartic acid with alanine at position 426 in the C1 domain (catalytic region) of AC6. Gene transfer of AC6 or AC6mut (adenovirus-mediated) in adult rat cardiac myocytes resulted in similar expression levels and intracellular distribution, but AC6mut expression was associated with marked reduction in cAMP production. Despite marked reduction in cAMP generation, AC6mut influenced intracellular signaling events similarly to that observed after expression of catalytically intact AC6. For example, both AC6 and AC6mut reduced phenylephrine-induced cardiac myocyte hypertrophy and apoptosis (p < 0.001), expression of cardiac ankyrin repeat protein (p < 0.01), and phospholamban (p < 0.05). AC6mut expression, similar to its catalytically intact cohort, was associated with increased Ca2+ transients in cardiac myocytes after isoproterenol stimulation. Many of the biological effects of AC6 expression are replicated by a catalytically inactive AC6 mutant, indicating that the mechanisms for these effects do not require increased cAMP generation. PMID:21127130

  6. Nonlinear interface optical switch structure for dual mode switching revisited

    NASA Astrophysics Data System (ADS)

    Bussjager, Rebecca J.; Osman, Joseph M.; Chaiken, Joseph

    1998-07-01

    There is a need for devices which will allow integration of photonic/optical computing subsystems into electronic computing architectures. This presentation reviews the nonlinear interface optical switch (NIOS) concept and then describes a new effect, the erasable optical memory (EOM) effect. We evaluate an extension of the NIOS device to allow simultaneous optical/electronic, i.e. dual mode, switching of light utilizing the EOM effect. Specific devices involve the fabrication of thin film tungsten (VI) oxide (WO3) and tungsten (V) oxide (W2O5) on the hypotenuse of glass (BK-7), fused silica (SiO2) and zinc selenide (ZnSe) right angle prisms. Chemical reactions and temporal response tests were performed and are discussed.

  7. Recent progress on silica-based optical switches and free-space optical switches

    NASA Astrophysics Data System (ADS)

    Himeno, Akira; Yamaguchi, Masayasu

    1996-03-01

    Space-division optical switches will be indispensable for future fiber-optic communication systems such as fiber-optic subscriber-line concentrators, photonic inter-module connectors, and protection switches. This paper reports recent progress on both silica-based thermo-optic optical switches with drive electronics. Two types of free-space switch modules are also reviewed; analog free-space switching modules which use liquid crystal beam shifters and digital free-space switching modules which incorporate semiconductor photonic switch array devices.

  8. Electronic logic to enhance switch reliability in detecting openings and closures of redundant switches

    DOEpatents

    Cooper, James A.

    1986-01-01

    A logic circuit is used to enhance redundant switch reliability. Two or more switches are monitored for logical high or low output. The output for the logic circuit produces a redundant and failsafe representation of the switch outputs. When both switch outputs are high, the output is high. Similarly, when both switch outputs are low, the logic circuit's output is low. When the output states of the two switches do not agree, the circuit resolves the conflict by memorizing the last output state which both switches were simultaneously in and produces the logical complement of this output state. Thus, the logic circuit of the present invention allows the redundant switches to be treated as if they were in parallel when the switches are open and as if they were in series when the switches are closed. A failsafe system having maximum reliability is thereby produced.

  9. The Autographa californica Multiple Nucleopolyhedrovirus ac54 Gene Is Crucial for Localization of the Major Capsid Protein VP39 at the Site of Nucleocapsid Assembly

    PubMed Central

    Guan, Zhanwen; Zhong, Ling; Li, Chunyan; Wu, Wenbi; Yuan, Meijin

    2016-01-01

    ABSTRACT Baculovirus DNAs are synthesized and inserted into preformed capsids to form nucleocapsids at a site in the infected cell nucleus, termed the virogenic stroma. Nucleocapsid assembly of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) requires the major capsid protein VP39 and nine minor capsid proteins, including VP1054. However, how VP1054 participates in nucleocapsid assembly remains elusive. In this study, the VP1054-encoding gene (ac54) was deleted to generate the ac54-knockout AcMNPV (vAc54KO). In vAc54KO-transfected cells, nucleocapsid assembly was disrupted, leading to the formation of abnormally elongated capsid structures. Interestingly, unlike cells transfected with AcMNPV mutants lacking other minor capsid proteins, in which capsid structures were distributed within the virogenic stroma, ac54 ablation resulted in a distinctive location of capsid structures and VP39 at the periphery of the nucleus. The altered distribution pattern of capsid structures was also observed in cells transfected with AcMNPV lacking BV/ODV-C42 or in cytochalasin d-treated AcMNPV-infected cells. BV/ODV-C42, along with PP78/83, has been shown to promote nuclear filamentous actin (F-actin) formation, which is another requisite for nucleocapsid assembly. Immunofluorescence using phalloidin indicated that the formation and distribution of nuclear F-actin were not affected by ac54 deletion. However, immunoelectron microscopy revealed that BV/ODV-C42, PP78/83, and 38K failed to integrate into capsid structures in the absence of VP1054, and immunoprecipitation further demonstrated that in transient expression assays, VP1054 interacted with BV/ODV-C42 and VP80 but not VP39. Our findings suggest that VP1054 plays an important role in the transport of capsid proteins to the nucleocapsid assembly site prior to the process of nucleocapsid assembly. IMPORTANCE Baculoviruses are large DNA viruses whose replication occurs within the host nucleus. The localization of

  10. Pulsed laser triggered high speed microfluidic switch

    NASA Astrophysics Data System (ADS)

    Wu, Ting-Hsiang; Gao, Lanyu; Chen, Yue; Wei, Kenneth; Chiou, Pei-Yu

    2008-10-01

    We report a high-speed microfluidic switch capable of achieving a switching time of 10 μs. The switching mechanism is realized by exciting dynamic vapor bubbles with focused laser pulses in a microfluidic polydimethylsiloxane (PDMS) channel. The bubble expansion deforms the elastic PDMS channel wall and squeezes the adjacent sample channel to control its fluid and particle flows as captured by the time-resolved imaging system. A switching of polystyrene microspheres in a Y-shaped channel has also been demonstrated. This ultrafast laser triggered switching mechanism has the potential to advance the sorting speed of state-of-the-art microscale fluorescence activated cell sorting devices.

  11. Secure videoconferencing equipment switching system and method

    DOEpatents

    Hansen, Michael E.

    2009-01-13

    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.

  12. Crossbar switch backplane and its application

    SciTech Connect

    Atac, R.; Cook, A.; Deepe, J.; Fischler, M.; Gaines, I.; Husby, D.; Nash, T.; Pham, T.; Zmuda, T.; Eichten, E.

    1988-11-01

    A crossbar switch backplane design (Bus Switch Backplane) based on TI's crossbar switch chip is described. This backplane holds a maximum of 16 modules and allows simultaneous communications between up to 8 pairs of modules. The aggregate data transfer rate on the backplane is 160 Mbyte/sec. The Bus Switch Backplane is an essential part of the ACP Multi Array Processor, a supercomputer for site oriented problems. The first application of this machine is in Lattice Gauge Theory calculations. The Bus Switch Backplane also finds ready application in data acquisition schemes based on the ACP multi-microprocessor system. 4 refs., 8 figs.

  13. Comprehensive review of high power factor ac-dc boost converters for PFC applications

    NASA Astrophysics Data System (ADS)

    De Castro Pereira, Dênis; Da Silva, Márcio Renato; Mateus Silva, Elder; Lessa Tofoli, Fernando

    2015-08-01

    High power factor rectifiers have been consolidated as an effective solution to improve power quality indices in terms of input power factor correction, reduction in the total harmonic distortion of the input current and also regulated dc voltages. Within this context, this subject has motivated the introduction of numerous converter topologies based on classic dc-dc structures associated with novel control techniques, thus leading to the manufacturing of dedicated integrated circuits that allow high input power factor by adding a front-end stage to switch-mode converters. In particular, boost converters in continuous current mode (CCM) are widely employed since they allow obtaining minimised electromagnetic interference levels. This work is concerned with a literature review involving relevant ac-dc single-phase boost-based topologies with high input power factor. The evolution of aspects regarding the conventional boost converter is shown in terms of improved characteristics inherent to other ac-dc boost converters. Additionally, the work intends to be a fast and concise reference to single-phase ac-dc boost converters operating in CCM for engineers, researchers and experts in the field of power electronics by properly analysing and comparing the aforementioned rectifiers.

  14. Very low noise AC/DC power supply systems for large detector arrays

    NASA Astrophysics Data System (ADS)

    Arnaboldi, C.; Baù, A.; Carniti, P.; Cassina, L.; Giachero, A.; Gotti, C.; Maino, M.; Passerini, A.; Pessina, G.

    2015-12-01

    In this work, we present the first part of the power supply system for the CUORE and LUCIFER arrays of bolometric detectors. For CUORE, it consists of AC/DC commercial power supplies (0-60 V output) followed by custom DC/DC modules (48 V input, ±5 V to ±13.5 V outputs). Each module has 3 floating and independently configurable output voltages. In LUCIFER, the AC/DC + DC/DC stages are combined into a commercial medium-power AC/DC source. At the outputs of both setups, we introduced filters with the aim of lowering the noise and to protect the following stages from high voltage spikes that can be generated by the energy stored in the cables after the release of accidental short circuits. Output noise is very low, as required: in the 100 MHz bandwidth the RMS level is about 37 μVRMS (CUORE setup) and 90 μVRMS (LUCIFER setup) at a load of 7 A, with a negligible dependence on the load current. Even more importantly, high frequency switching disturbances are almost completely suppressed. The efficiency of both systems is above 85%. Both systems are completely programmable and monitored via CAN bus (optically coupled).

  15. Shape memory thermal conduction switch

    NASA Technical Reports Server (NTRS)

    Vaidyanathan, Rajan (Inventor); Krishnan, Vinu (Inventor); Notardonato, William U. (Inventor)

    2010-01-01

    A thermal conduction switch includes a thermally-conductive first member having a first thermal contacting structure for securing the first member as a stationary member to a thermally regulated body or a body requiring thermal regulation. A movable thermally-conductive second member has a second thermal contacting surface. A thermally conductive coupler is interposed between the first member and the second member for thermally coupling the first member to the second member. At least one control spring is coupled between the first member and the second member. The control spring includes a NiTiFe comprising shape memory (SM) material that provides a phase change temperature <273 K, a transformation range <40 K, and a hysteresis of <10 K. A bias spring is between the first member and the second member. At the phase change the switch provides a distance change (displacement) between first and second member by at least 1 mm, such as 2 to 4 mm.

  16. High power ferrite microwave switch

    NASA Technical Reports Server (NTRS)

    Bardash, I.; Roschak, N. K.

    1975-01-01

    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.

  17. Transient AC voltage related phenomena for HVDC schemes connected to weak AC systems

    SciTech Connect

    Pilotto, L.A.S.; Szechtman, M. ); Hammad, A.E. )

    1992-07-01

    In this paper a didactic explanation of voltage stability associated phenomena at HVDC terminals is presented. Conditions leading to ac voltage collapse problems are identified. A mechanism that excites control-induced voltage oscillations is shown. The voltage stability factor is used for obtaining the maximum power limits of ac/dc systems operating with different control strategies. Correlation to Pd {times} Id curves is given. Solutions for eliminating the risks of voltage collapse and for avoiding control-induced oscillations are discussed. The results are supported by detailed digital simulations of a weak ac/dc system using EMTP.

  18. Switch for Good Community Program

    SciTech Connect

    Crawford, Tabitha; Amran, Martha

    2013-11-19

    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.

  19. Correlated randomness and switching phenomena

    NASA Astrophysics Data System (ADS)

    Stanley, H. E.; Buldyrev, S. V.; Franzese, G.; Havlin, S.; Mallamace, F.; Kumar, P.; Plerou, V.; Preis, T.

    2010-08-01

    One challenge of biology, medicine, and economics is that the systems treated by these serious scientific disciplines have no perfect metronome in time and no perfect spatial architecture-crystalline or otherwise. Nonetheless, as if by magic, out of nothing but randomness one finds remarkably fine-tuned processes in time and remarkably fine-tuned structures in space. Further, many of these processes and structures have the remarkable feature of “switching” from one behavior to another as if by magic. The past century has, philosophically, been concerned with placing aside the human tendency to see the universe as a fine-tuned machine. Here we will address the challenge of uncovering how, through randomness (albeit, as we shall see, strongly correlated randomness), one can arrive at some of the many spatial and temporal patterns in biology, medicine, and economics and even begin to characterize the switching phenomena that enables a system to pass from one state to another. Inspired by principles developed by A. Nihat Berker and scores of other statistical physicists in recent years, we discuss some applications of correlated randomness to understand switching phenomena in various fields. Specifically, we present evidence from experiments and from computer simulations supporting the hypothesis that water’s anomalies are related to a switching point (which is not unlike the “tipping point” immortalized by Malcolm Gladwell), and that the bubbles in economic phenomena that occur on all scales are not “outliers” (another Gladwell immortalization). Though more speculative, we support the idea of disease as arising from some kind of yet-to-be-understood complex switching phenomenon, by discussing data on selected examples, including heart disease and Alzheimer disease.

  20. Switching strategies to optimize search

    NASA Astrophysics Data System (ADS)

    Shlesinger, Michael F.

    2016-03-01

    Search strategies are explored when the search time is fixed, success is probabilistic and the estimate for success can diminish with time if there is not a successful result. Under the time constraint the problem is to find the optimal time to switch a search strategy or search location. Several variables are taken into account, including cost, gain, rate of success if a target is present and the probability that a target is present.

  1. AcsA-AcsB: The core of the cellulose synthase complex from Gluconacetobacter hansenii ATCC23769.

    PubMed

    McManus, John B; Deng, Ying; Nagachar, Nivedita; Kao, Teh-hui; Tien, Ming

    2016-01-01

    The gram-negative bacterium, Gluconacetobacter hansenii, produces cellulose of exceptionally high crystallinity in comparison to the cellulose of higher plants. This bacterial cellulose is synthesized and extruded into the extracellular medium by the cellulose synthase complex (CSC). The catalytic component of this complex is encoded by the gene AcsAB. However, several other genes are known to encode proteins critical to cellulose synthesis and are likely components of the bacterial CSC. We have purified an active heterodimer AcsA-AcsB from G. hansenii ATCC23769 to homogeneity by two different methods. With the purified protein, we have determined how it is post-translationally processed, forming the active heterodimer AcsA-AcsB. Additionally, we have performed steady-state kinetic studies on the AcsA-AcsB complex. Finally through mutagenesis studies, we have explored the roles of the postulated CSC proteins AcsC, AcsD, and CcpAx. PMID:26672449

  2. AcsA-AcsB: The core of the cellulose synthase complex from Gluconacetobacter hansenii ATCC23769.

    PubMed

    McManus, John B; Deng, Ying; Nagachar, Nivedita; Kao, Teh-hui; Tien, Ming

    2016-01-01

    The gram-negative bacterium, Gluconacetobacter hansenii, produces cellulose of exceptionally high crystallinity in comparison to the cellulose of higher plants. This bacterial cellulose is synthesized and extruded into the extracellular medium by the cellulose synthase complex (CSC). The catalytic component of this complex is encoded by the gene AcsAB. However, several other genes are known to encode proteins critical to cellulose synthesis and are likely components of the bacterial CSC. We have purified an active heterodimer AcsA-AcsB from G. hansenii ATCC23769 to homogeneity by two different methods. With the purified protein, we have determined how it is post-translationally processed, forming the active heterodimer AcsA-AcsB. Additionally, we have performed steady-state kinetic studies on the AcsA-AcsB complex. Finally through mutagenesis studies, we have explored the roles of the postulated CSC proteins AcsC, AcsD, and CcpAx.

  3. Influence of AC and DC electrical stimulation on wound healing in pigs: a biomechanical analysis.

    PubMed

    Kambic, H E; Reyes, E; Manning, T; Waters, K C; Reger, S I

    1993-01-01

    To evaluate the effects of electrical stimulation on the mechanical properties of healing skin, 20 Hanford mini-pigs weighing 10-15 kg with trochanteric pressure ulcers were subjected to electrical stimulation. Examination of the biomechanical properties of the skin and changes in wound area and volume was done on previously wounded and healing pigskin subject to AC or DC electrical stimulation. The behavior of normal pigskin was compared to (1) denervated controls, (2) denervated AC-stimulated skin, and (3) denervated DC-stimulated skin. A denervated limb trochanteric pressure sore model developed in house permitted the use of a 6.5-mm percutaneous cancellous screw for wound formation and a 3-cm-diameter spring compression indentor to create reproducible and uniformly controlled grade 3 or higher tissue ulcers in the monoplegic hind limbs. Denervation was accomplished by right unilateral extradural rhizotomies from L2 to S1 nerve roots. Electrodes were placed 1 cm distal and proximal to the wound periphery, and wounds were stimulated 2 h/day, 5 days/week for 30 days. Dumbbell-shaped skin specimens with a length to width ratio of 3:1 were uniaxially loaded in tension until failure at an extension rate of 150 mm/min. The stiffness values for skin samples oriented parallel to the current flow were reduced by nearly half the values obtained for normal controls. Statistical differences (P < .05) were found for stress, Young modulus, and stiffness when compared to normal skin. Samples oriented in the perpendicular direction were comparable to normal skin (P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

  4. Electrical switching in cadmium boracite single crystals

    NASA Technical Reports Server (NTRS)

    Takahashi, T.; Yamada, O.

    1981-01-01

    Cadmium boracite single crystals at high temperatures ( 300 C) were found to exhibit a reversible electric field-induced transition between a highly insulative and a conductive state. The switching threshold is smaller than a few volts for an electrode spacing of a few tenth of a millimeter corresponding to an electric field of 100 to 1000 V/cm. This is much smaller than the dielectric break-down field for an insulator such as boracite. The insulative state reappears after voltage removal. A pulse technique revealed two different types of switching. Unstable switching occurs when the pulse voltage slightly exceeds the switching threshold and is characterized by a pre-switching delay and also a residual current after voltage pulse removal. A stable type of switching occurs when the voltage becomes sufficiently high. Possible device applications of this switching phenomenon are discussed.

  5. Fast superconducting magnetic field switch

    DOEpatents

    Goren, Yehuda; Mahale, Narayan K.

    1996-01-01

    The superconducting magnetic switch or fast kicker magnet is employed with electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater that the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles.

  6. Fast superconducting magnetic field switch

    DOEpatents

    Goren, Y.; Mahale, N.K.

    1996-08-06

    The superconducting magnetic switch or fast kicker magnet is employed with electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater that the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles. 6 figs.

  7. Meristem-Specific Suppression of Mitosis and a Global Switch in Gene Expression in the Root Cap of Pea by Endogenous Signals1

    PubMed Central

    Brigham, Lindy A.; Woo, Ho-Hyung; Wen, Fushi; Hawes, Martha C.

    1998-01-01

    Two functionally distinct sets of meristematic cells exist within root tips of pea (Pisum sativum): the root apical meristem, which gives rise to the body of the root; and the root cap meristem, which gives rise to cells that differentiate progressively through the cap and separate ultimately from its periphery as border cells. When a specific number of border cells has accumulated on the root cap periphery, mitosis within the root cap meristem, but not the apical meristem, is suppressed. When border cells are removed by immersion of the root tip in water, a transient induction of mitosis in the root cap meristem can be detected starting within 5 min. A corresponding switch in gene expression throughout the root cap occurs in parallel with the increase in mitosis, and new border cells begin to separate from the root cap periphery within 1 h. The induction of renewed border cell production is inhibited by incubating root tips in extracellular material released from border cells. The results are consistent with the hypothesis that operation of the root cap meristem and consequent turnover of the root cap is self-regulated by a signal from border cells. PMID:9847096

  8. A dry-cooled AC quantum voltmeter

    NASA Astrophysics Data System (ADS)

    Schubert, M.; Starkloff, M.; Peiselt, K.; Anders, S.; Knipper, R.; Lee, J.; Behr, R.; Palafox, L.; Böck, A. C.; Schaidhammer, L.; Fleischmann, P. M.; Meyer, H.-G.

    2016-10-01

    The paper describes a dry-cooled AC quantum voltmeter system operated up to kilohertz frequencies and 7 V rms. A 10 V programmable Josephson voltage standard (PJVS) array was installed on a pulse tube cooler (PTC) driven with a 4 kW air-cooled compressor. The operating margins at 70 GHz frequencies were investigated in detail and found to exceed 1 mA Shapiro step width. A key factor for the successful chip operation was the low on-chip power consumption of 65 mW in total. A thermal interface between PJVS chip and PTC cold stage was used to avoid a significant chip overheating. By installing the cryocooled PJVS array into an AC quantum voltmeter setup, several calibration measurements of dc standards and calibrator ac voltages up to 2 kHz frequencies were carried out to demonstrate the full functionality. The results are discussed and compared to systems with standard liquid helium cooling. For dc voltages, a direct comparison measurement between the dry-cooled AC quantum voltmeter and a liquid-helium based 10 V PJVS shows an agreement better than 1 part in 1010.

  9. AC power generation from microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Lobo, Fernanda Leite; Wang, Heming; Forrestal, Casey; Ren, Zhiyong Jason

    2015-11-01

    Microbial fuel cells (MFCs) directly convert biodegradable substrates to electricity and carry good potential for energy-positive wastewater treatment. However, the low and direct current (DC) output from MFC is not usable for general electronics except small sensors, yet commercial DC-AC converters or inverters used in solar systems cannot be directly applied to MFCs. This study presents a new DC-AC converter system for MFCs that can generate alternating voltage in any desired frequency. Results show that AC power can be easily achieved in three different frequencies tested (1, 10, 60 Hz), and no energy storage layer such as capacitors was needed. The DC-AC converter efficiency was higher than 95% when powered by either individual MFCs or simple MFC stacks. Total harmonic distortion (THD) was used to investigate the quality of the energy, and it showed that the energy could be directly usable for linear electronic loads. This study shows that through electrical conversion MFCs can be potentially used in household electronics for decentralized off-grid communities.

  10. Manipulating Flames with AC Electric Fields

    NASA Astrophysics Data System (ADS)

    Bishop, Kyle

    2013-11-01

    Time-oscillating electric fields applied to plasmas present in flames create steady flows of gas capable of shaping, directing, enhancing, or even extinguishing flames. Interestingly, electric winds induced by AC electric fields can be stronger that those due to static fields of comparable magnitude. Furthermore, unlike static fields, the electric force due to AC fields is localized near the surface of the flame. Consequently, the AC response depends only on the local field at the surface of the flame - not on the position of the electrodes used to generate the field. These results suggest that oscillating electric fields can be used to manipulate and control combustion processes at a distance. To characterize and explain these effects, we investigate a simple experimental system comprising a laminar methane-air flame positioned between two parallel-plate electrodes. We quantify both the electric and hydrodynamic response of the flame as a function of frequency and magnitude of the applied field. A theoretical model shows how steady gas flows emerge from the time-averaged electrical force due to the field-induced motion of ions generated within the flame and by their disappearance by recombination. These results provide useful insights into the application of AC fields to direct combustion processes.

  11. Ac-dc converter firing error detection

    SciTech Connect

    Gould, O.L.

    1996-07-15

    Each of the twelve Booster Main Magnet Power Supply modules consist of two three-phase, full-wave rectifier bridges in series to provide a 560 VDC maximum output. The harmonic contents of the twelve-pulse ac-dc converter output are multiples of the 60 Hz ac power input, with a predominant 720 Hz signal greater than 14 dB in magnitude above the closest harmonic components at maximum output. The 720 Hz harmonic is typically greater than 20 dB below the 500 VDC output signal under normal operation. Extracting specific harmonics from the rectifier output signal of a 6, 12, or 24 pulse ac-dc converter allows the detection of SCR firing angle errors or complete misfires. A bandpass filter provides the input signal to a frequency-to-voltage converter. Comparing the output of the frequency-to-voltage converter to a reference voltage level provides an indication of the magnitude of the harmonics in the ac-dc converter output signal.

  12. Genetic enrichment of the arctic clonal plant Saxifraga cernua at its southern periphery via the alpine sexual Saxifraga sibirica.

    PubMed

    Kapralov, Maxim V; Gabrielsen, Tove M; Sarapultsev, Ivan E; Brochmann, Christian

    2006-10-01

    Isolation of populations at the margins of a species range may lead to decreasing genetic diversity via genetic drift and inbreeding. Hybridization between peripheral populations of two species can, however, counteract genetic impoverishment. The mainly clonal, polyploid plant Saxifraga cernua has a wide arctic distribution but also extends southwards into alpine sites. In the Ural Mountains, its peripheral distribution overlaps with that of its sexually reproducing, diploid relative Saxifraga sibirica, and fertile polyploids of more or less intermediate appearance are found in this overlap zone. We used amplified fragment length polymorphism (AFLP) analysis to address the potential impact of interspecific gene flow on genetic diversity in the peripheral populations. A total of 149 plants from 17 populations along a 1650 km south-north gradient were analysed for 253 markers. The results suggest that three Middle Ural populations containing fertile and morphologically more or less intermediate plants have been affected by hybridization. All of these plants formed a strongly supported (100%) group with S. cernua in a neighbour-joining tree, but their AFLP phenotypes assigned either to S. cernua or to artificial (simulated) F(1) hybrids between S. cernua and S. sibirica in multilocus assignment tests. The three populations were highly diverse with virtually every plant representing a distinct AFLP phenotype, providing additional evidence for formation of later-generation hybrids and/or backcrossing to S. cernua. In contrast, other peripheral populations of S. cernua were typically monoclonal, suggesting that hybridization with S. sibirica can increase genetic diversity in S. cernua at its southern periphery.

  13. The mobile thylakoid phosphoprotein TSP9 interacts with the light-harvesting complex II and the peripheries of both photosystems.

    PubMed

    Hansson, Maria; Dupuis, Tiphaine; Strömquist, Ragna; Andersson, Bertil; Vener, Alexander V; Carlberg, Inger

    2007-06-01

    The localization of the plant-specific thylakoid-soluble phosphoprotein of 9 kDa, TSP9, within the chloroplast thylakoid membrane of spinach has been established by the combined use of fractionation, immunoblotting, cross-linking, and mass spectrometry. TSP9 was found to be exclusively confined to the thylakoid membranes, where it is enriched in the stacked grana membrane domains. After mild solubilization of the membranes, TSP9 migrated together with the major light-harvesting antenna (LHCII) of photosystem II (PSII) and with PSII-LHCII supercomplexes upon separation of the protein complexes by either native gel electrophoresis or sucrose gradient centrifugation. Studies with a cleavable cross-linking agent revealed the interaction of TSP9 with both major and minor LHCII proteins as identified by mass spectrometric sequencing. Cross-linked complexes that in addition to TSP9 contain the peripheral PSII subunits CP29, CP26, and PsbS, which form the interface between LHCII and the PSII core, were found. Our observations also clearly suggest an interaction of TSP9 with photosystem I (PSI) as shown by both immunodetection and mass spectrometry. Sequencing identified the peripheral PSI subunits PsaL, PsaF, and PsaE, originating from cross-linked protein complexes of around 30 kDa that also contained TSP9. The distribution of TSP9 among the cross-linked forms was found to be sensitive to conditions such as light exposure. An association of TSP9 with LHCII as well as the peripheries of the photosystems suggests its involvement in regulation of photosynthetic light harvesting. PMID:17400553

  14. Genetic enrichment of the arctic clonal plant Saxifraga cernua at its southern periphery via the alpine sexual Saxifraga sibirica.

    PubMed

    Kapralov, Maxim V; Gabrielsen, Tove M; Sarapultsev, Ivan E; Brochmann, Christian

    2006-10-01

    Isolation of populations at the margins of a species range may lead to decreasing genetic diversity via genetic drift and inbreeding. Hybridization between peripheral populations of two species can, however, counteract genetic impoverishment. The mainly clonal, polyploid plant Saxifraga cernua has a wide arctic distribution but also extends southwards into alpine sites. In the Ural Mountains, its peripheral distribution overlaps with that of its sexually reproducing, diploid relative Saxifraga sibirica, and fertile polyploids of more or less intermediate appearance are found in this overlap zone. We used amplified fragment length polymorphism (AFLP) analysis to address the potential impact of interspecific gene flow on genetic diversity in the peripheral populations. A total of 149 plants from 17 populations along a 1650 km south-north gradient were analysed for 253 markers. The results suggest that three Middle Ural populations containing fertile and morphologically more or less intermediate plants have been affected by hybridization. All of these plants formed a strongly supported (100%) group with S. cernua in a neighbour-joining tree, but their AFLP phenotypes assigned either to S. cernua or to artificial (simulated) F(1) hybrids between S. cernua and S. sibirica in multilocus assignment tests. The three populations were highly diverse with virtually every plant representing a distinct AFLP phenotype, providing additional evidence for formation of later-generation hybrids and/or backcrossing to S. cernua. In contrast, other peripheral populations of S. cernua were typically monoclonal, suggesting that hybridization with S. sibirica can increase genetic diversity in S. cernua at its southern periphery. PMID:16968278

  15. Screening of urocanic acid isomers in human basal and squamous cell carcinoma tumors compared with tumor periphery and healthy skin.

    PubMed

    Decara, Juan Manuel; Aguilera, José; Abdala, Roberto; Sánchez, Purificación; Figueroa, Félix L; Herrera, Enrique

    2008-10-01

    Trans-urocanic acid is a major chromophore for ultraviolet (UV) radiation in human epidermis. The UV induces photoisomerization of trans-urocanic acid (tUCA) form to cis-urocanic acid (cUCA) and has been reported as an important mediator in the immunosuppression induced by UV. This immunomodulation has been recognized as an important factor related to skin cancer development. This is the first time that UCA isomers have been measured in epidermis of skin biopsies from patients with squamous cell carcinoma (SCC) and with basal cell carcinoma (BCC) and compared with the tumor periphery and biopsies of healthy photoexposed and non-photoexposed skin as controls. The UCA isomers were separated and quantified by high performance liquid chromatography. Analysis of UCA in healthy skin showed significant increase in total UCA content in non-photoexposed body sites compared with highly exposed skins. In contrast, the percentage of cUCA was higher in photoexposed body sites. Maximal levels of cUCA were found in cheek, forehead and forearm and lower levels in abdomen and thigh. No differences were found in total UCA concentration between the tumor samples and healthy photoexposed skin. However, differences were found in relation between isomers. Higher levels of cUCA were detected in SCC biopsies (44% of total UCA) compared with samples of BCC and that of healthy photoexposed skin (30%). These results suggest that the UV radiation exposure, a main factor in development of SCC can be mediated, apart from direct effect to cells (DNA damage), by immunosuppression pathways mediated by high production of cUCA. PMID:18312386

  16. High voltage AC/AC electrochemical capacitor operating at low temperature in salt aqueous electrolyte

    NASA Astrophysics Data System (ADS)

    Abbas, Qamar; Béguin, François

    2016-06-01

    We demonstrate that an activated carbon (AC)-based electrochemical capacitor implementing aqueous lithium sulfate electrolyte in 7:3 vol:vol water/methanol mixture can operate down to -40 °C with good electrochemical performance. Three-electrode cell investigations show that the faradaic contributions related with hydrogen chemisorption in the negative AC electrode are thermodynamically unfavored at -40 °C, enabling the system to work as a typical electrical double-layer (EDL) capacitor. After prolonged floating of the AC/AC capacitor at 1.6 V and -40°C, the capacitance, equivalent series resistance and efficiency remain constant, demonstrating the absence of ageing related with side redox reactions at this temperature. Interestingly, when temperature is increased back to 24 °C, the redox behavior due to hydrogen storage reappears and the system behaves as a freshly prepared one.

  17. 48 CFR Appendixes A-C to Chapter 7 - [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false A Appendixes A-C to Chapter 7 Federal Acquisition Regulations System AGENCY FOR INTERNATIONAL DEVELOPMENT Appendixes A-C to Chapter 7...

  18. 48 CFR Appendixes A-C to Chapter 7 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false A Appendixes A-C to Chapter 7 Federal Acquisition Regulations System AGENCY FOR INTERNATIONAL DEVELOPMENT Appendixes A-C to Chapter 7...

  19. 21 CFR 886.1630 - AC-powered photostimulator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) Identification. An AC-powered photostimulator is an AC-powered device intended to provide light stimulus which allows measurement of retinal or visual function by perceptual or electrical methods (e.g.,...

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    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.