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Sample records for high specific impulse

  1. The evolutionary development of high specific impulse electric thruster technology

    NASA Technical Reports Server (NTRS)

    Sovey, James S.; Hamley, John A.; Patterson, Michael J.; Rawlin, Vincent K.; Myers, Roger M.

    1992-01-01

    Electric propulsion flight and technology demonstrations conducted primarily by Europe, Japan, China, the U.S., and the USSR are reviewed. Evolutionary mission applications for high specific impulse electric thruster systems are discussed, and the status of arcjet, ion, and magnetoplasmadynamic thrusters and associated power processor technologies are summarized.

  2. Efficiency Analysis of a High-Specific Impulse Hall Thruster

    NASA Technical Reports Server (NTRS)

    Jacobson, David (Technical Monitor); Hofer, Richard R.; Gallimore, Alec D.

    2004-01-01

    Performance and plasma measurements of the high-specific impulse NASA-173Mv2 Hall thruster were analyzed using a phenomenological performance model that accounts for a partially-ionized plasma containing multiply-charged ions. Between discharge voltages of 300 to 900 V, the results showed that although the net decrease of efficiency due to multiply-charged ions was only 1.5 to 3.0 percent, the effects of multiply-charged ions on the ion and electron currents could not be neglected. Between 300 to 900 V, the increase of the discharge current was attributed to the increasing fraction of multiply-charged ions, while the maximum deviation of the electron current from its average value was only +5/-14 percent. These findings revealed how efficient operation at high-specific impulse was enabled through the regulation of the electron current with the applied magnetic field. Between 300 to 900 V, the voltage utilization ranged from 89 to 97 percent, the mass utilization from 86 to 90 percent, and the current utilization from 77 to 81 percent. Therefore, the anode efficiency was largely determined by the current utilization. The electron Hall parameter was nearly constant with voltage, decreasing from an average of 210 at 300 V to an average of 160 between 400 to 900 V. These results confirmed our claim that efficient operation can be achieved only over a limited range of Hall parameters.

  3. Solar-powered rocket engine optimization for high specific impulse

    NASA Astrophysics Data System (ADS)

    Pande, J. Bradley

    1993-11-01

    Hercules Aerospace is currently developing a solar-powered rocket engine (SPRE) design optimized for high specific impulse (Isp). The SPRE features a low loss geometry in its light-gathering cavity, which includes an integral secondary concentrator. The simple one-piece heat exchanger is made from refractory metal and/or ceramic open-celled foam. The foam's high surface-area-to-volume ratio will efficiently transfer the thermal energy to the hydrogen propellant. The single-pass flow of propellant through the heat exchanger further boosts thermal efficiency by regeneratively cooling surfaces near the entrance of the optical cavity. These surfaces would otherwise reradiate a significant portion of the captured solar energy back out of the solar entrance. Such design elements promote a high overall thermal efficiency and hence, a high operating Isp

  4. A Very-High-Specific-Impulse Relativistic Laser Thruster

    SciTech Connect

    Horisawa, Hideyuki; Kimura, Itsuro

    2008-04-28

    Characteristics of compact laser plasma accelerators utilizing high-power laser and thin-target interaction were reviewed as a potential candidate of future spacecraft thrusters capable of generating relativistic plasma beams for interstellar missions. Based on the special theory of relativity, motion of the relativistic plasma beam exhausted from the thruster was formulated. Relationships of thrust, specific impulse, input power and momentum coupling coefficient for the relativistic plasma thruster were derived. It was shown that under relativistic conditions, the thrust could be extremely large even with a small amount of propellant flow rate. Moreover, it was shown that for a given value of input power thrust tended to approach the value of the photon rocket under the relativistic conditions regardless of the propellant flow rate.

  5. Plasmoid Thruster for High Specific-Impulse Propulsion

    NASA Technical Reports Server (NTRS)

    Fimognari, Peter; Eskridge, Richard; Martin, Adam; Lee, Michael

    2007-01-01

    A report discusses a new multi-turn, multi-lead design for the first generation PT-1 (Plasmoid Thruster) that produces thrust by expelling plasmas with embedded magnetic fields (plasmoids) at high velocities. This thruster is completely electrodeless, capable of using in-situ resources, and offers efficiencies as high as 70 percent at a specific impulse, I(sub sp), of up to 8,000 s. This unit consists of drive and bias coils wound around a ceramic form, and the capacitor bank and switches are an integral part of the assembly. Multiple thrusters may be gauged to inductively recapture unused energy to boost efficiency and to increase the repetition rate, which, in turn increases the average thrust of the system. The thruster assembly can use storable propellants such as H2O, ammonia, and NO, among others. Any available propellant gases can be used to produce an I(sub sp) in the range of 2,000 to 8,000 s with a single-stage thruster. These capabilities will allow the transport of greater payloads to outer planets, especially in the case of an I(sub sp) greater than 6,000 s.

  6. Coaxial plasma thrusters for high specific impulse propulsion

    NASA Technical Reports Server (NTRS)

    Schoenberg, Kurt F.; Gerwin, Richard A.; Barnes, Cris W.; Henins, Ivars; Mayo, Robert; Moses, Ronald, Jr.; Scarberry, Richard; Wurden, Glen

    1991-01-01

    A fundamental basis for coaxial plasma thruster performance is presented and the steady-state, ideal MHD properties of a coaxial thruster using an annular magnetic nozzle are discussed. Formulas for power usage, thrust, mass flow rate, and specific impulse are acquired and employed to assess thruster performance. The performance estimates are compared with the observed properties of an unoptimized coaxial plasma gun. These comparisons support the hypothesis that ideal MHD has an important role in coaxial plasma thruster dynamics.

  7. Coaxial plasma thrusters for high specific impulse propulsion

    NASA Technical Reports Server (NTRS)

    Schoenberg, Kurt F.; Gerwin, Richard A.; Barnes, Cris W.; Henins, Ivars; Mayo, Robert; Moses, Ronald, Jr.; Scarberry, Richard; Wurden, Glen

    1991-01-01

    A fundamental basis for coaxial plasma thruster performance is presented and the steady-state, ideal MHD properties of a coaxial thruster using an annular magnetic nozzle are discussed. Formulas for power usage, thrust, mass flow rate, and specific impulse are acquired and employed to assess thruster performance. The performance estimates are compared with the observed properties of an unoptimized coaxial plasma gun. These comparisons support the hypothesis that ideal MHD has an important role in coaxial plasma thruster dynamics.

  8. An Analytic Approximation to Very High Specific Impulse and Specific Power Interplanetary Space Mission Analysis

    NASA Technical Reports Server (NTRS)

    Williams, Craig Hamilton

    1995-01-01

    A simple, analytic approximation is derived to calculate trip time and performance for propulsion systems of very high specific impulse (50,000 to 200,000 seconds) and very high specific power (10 to 1000 kW/kg) for human interplanetary space missions. The approach assumed field-free space, constant thrust/constant specific power, and near straight line (radial) trajectories between the planets. Closed form, one dimensional equations of motion for two-burn rendezvous and four-burn round trip missions are derived as a function of specific impulse, specific power, and propellant mass ratio. The equations are coupled to an optimizing parameter that maximizes performance and minimizes trip time. Data generated for hypothetical one-way and round trip human missions to Jupiter were found to be within 1% and 6% accuracy of integrated solutions respectively, verifying that for these systems, credible analysis does not require computationally intensive numerical techniques.

  9. Trajectories for High Specific Impulse High Specific Power Deep Space Exploration

    NASA Technical Reports Server (NTRS)

    Polsgrove, T.; Adams, R. B.; Brady, Hugh J. (Technical Monitor)

    2002-01-01

    Preliminary results are presented for two methods to approximate the mission performance of high specific impulse high specific power vehicles. The first method is based on an analytical approximation derived by Williams and Shepherd and can be used to approximate mission performance to outer planets and interstellar space. The second method is based on a parametric analysis of trajectories created using the well known trajectory optimization code, VARITOP. This parametric analysis allows the reader to approximate payload ratios and optimal power requirements for both one-way and round-trip missions. While this second method only addresses missions to and from Jupiter, future work will encompass all of the outer planet destinations and some interstellar precursor missions.

  10. Simulation of Trajectories for High Specific Impulse Deep Space Exploration

    NASA Technical Reports Server (NTRS)

    Polsgrove, Tara; Adams, Robert B.; Brady, Hugh J. (Technical Monitor)

    2002-01-01

    Difficulties in approximating flight times and deliverable masses for continuous thrust propulsion systems have complicated comparison and evaluation of proposed propulsion concepts. These continuous thrust propulsion systems are of interest to many groups, not the least of which are the electric propulsion and fusion communities. Several charts plotting the results of well-known trajectory simulation codes were developed and are contained in this paper. These charts illustrate the dependence of time of flight and payload ratio on jet power, initial mass, specific impulse and specific power. These charts are intended to be a tool by which people in the propulsion community can explore the possibilities of their propulsion system concepts. Trajectories were simulated using the tools VARITOP and IPOST. VARITOP is a well known trajectory optimization code that involves numerical integration based on calculus of variations. IPOST has several methods of trajectory simulation; the one used in this paper is Cowell's method for full integration of the equations of motion. The analytical method derived in the companion paper was also used to simulate the trajectory. The accuracy of this method is discussed in the paper.

  11. Development and Characterization of High-Efficiency, High-Specific Impulse Xenon Hall Thrusters

    NASA Technical Reports Server (NTRS)

    Hofer, Richard R.; Jacobson, David (Technical Monitor)

    2004-01-01

    This dissertation presents research aimed at extending the efficient operation of 1600 s specific impulse Hall thruster technology to the 2000 to 3000 s range. Motivated by previous industry efforts and mission studies, the aim of this research was to develop and characterize xenon Hall thrusters capable of both high-specific impulse and high-efficiency operation. During the development phase, the laboratory-model NASA 173M Hall thrusters were designed and their performance and plasma characteristics were evaluated. Experiments with the NASA-173M version 1 (v1) validated the plasma lens magnetic field design. Experiments with the NASA 173M version 2 (v2) showed there was a minimum current density and optimum magnetic field topography at which efficiency monotonically increased with voltage. Comparison of the thrusters showed that efficiency can be optimized for specific impulse by varying the plasma lens. During the characterization phase, additional plasma properties of the NASA 173Mv2 were measured and a performance model was derived. Results from the model and experimental data showed how efficient operation at high-specific impulse was enabled through regulation of the electron current with the magnetic field. The electron Hall parameter was approximately constant with voltage, which confirmed efficient operation can be realized only over a limited range of Hall parameters.

  12. Trajectories for High Specific Impulse High Specific Power Deep Space Exploration

    NASA Technical Reports Server (NTRS)

    Polsgrove, Tara; Adams, Robert B.; Brady, Hugh J. (Technical Monitor)

    2002-01-01

    Flight times and deliverable masses for electric and fusion propulsion systems are difficult to approximate. Numerical integration is required for these continuous thrust systems. Many scientists are not equipped with the tools and expertise to conduct interplanetary and interstellar trajectory analysis for their concepts. Several charts plotting the results of well-known trajectory simulation codes were developed and are contained in this paper. These charts illustrate the dependence of time of flight and payload ratio on jet power, initial mass, specific impulse and specific power. These charts are intended to be a tool by which people in the propulsion community can explore the possibilities of their propulsion system concepts. Trajectories were simulated using the tools VARITOP and IPOST. VARITOP is a well known trajectory optimization code that involves numerical integration based on calculus of variations. IPOST has several methods of trajectory simulation; the one used in this paper is Cowell's method for full integration of the equations of motion. An analytical method derived in the companion paper was also evaluated. The accuracy of this method is discussed in the paper.

  13. A centre-triggered magnesium fuelled cathodic arc thruster uses sublimation to deliver a record high specific impulse

    NASA Astrophysics Data System (ADS)

    Neumann, Patrick R. C.; Bilek, Marcela; McKenzie, David R.

    2016-08-01

    The cathodic arc is a high current, low voltage discharge that operates in vacuum and provides a stream of highly ionised plasma from a solid conducting cathode. The high ion velocities, together with the high ionisation fraction and the quasineutrality of the exhaust stream, make the cathodic arc an attractive plasma source for spacecraft propulsion applications. The specific impulse of the cathodic arc thruster is substantially increased when the emission of neutral species is reduced. Here, we demonstrate a reduction of neutral emission by exploiting sublimation in cathode spots and enhanced ionisation of the plasma in short, high-current pulses. This, combined with the enhanced directionality due to the efficient erosion profiles created by centre-triggering, substantially increases the specific impulse. We present experimentally measured specific impulses and jet power efficiencies for titanium and magnesium fuels. Our Mg fuelled source provides the highest reported specific impulse for a gridless ion thruster and is competitive with all flight rated ion thrusters. We present a model based on cathode sublimation and melting at the cathodic arc spot explaining the outstanding performance of the Mg fuelled source. A further significant advantage of an Mg-fuelled thruster is the abundance of Mg in asteroidal material and in space junk, providing an opportunity for utilising these resources in space.

  14. Design Analysis of a High Temperature Radiator for the Variable Specific Impulse Magnetoplasma Rocket (VASIMR)

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik B.; Ungar, Eugene K.; Chambliss, Joe P.; Cassady, Leonard D.

    2011-01-01

    The Variable Specific Impulse Magnetoplasma Rocket (VASIMR), currently under development by Ad Astra Rocket Company, is a unique propulsion system that can potentially change the way space propulsion is performed. VASIMR's efficiency, when compared to that of a conventional chemical rocket, reduce propellant needed for exploration missions by a factor of 10. Currently plans include flight tests of a 200 kW VASIMR system, titled VF-200, on the International Space Station. The VF-200 will consist of two 100 kW thruster units packaged together in one engine bus. Each thruster unit has a unique heat rejection requirement of about 27 kW over a firing time of 15 minutes. In order to control rocket core temperatures, peak operating temperatures of about 300 C are expected within the thermal control loop. Design of a high temperature radiator is a unique challenge for the vehicle design. This paper will discuss the path taken to develop a steady state and transient based radiator design. The paper will describe radiator design options for the VASIMR thermal control system for use on ISS as well as future exploration vehicles.

  15. Design of a High Temperature Radiator for the Variable Specific Impulse Magnetoplasma Rocket

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik B.; Ungar, Eugene K.; Chambliss, Joe P.

    2012-01-01

    The Variable Specific Impulse Magnetoplasma Rocket (VASIMR), currently under development by Ad Astra Rocket Company (Webster, TX), is a unique propulsion system that could change the way space propulsion is performed. VASIMR's efficiency, when compared to that of a conventional chemical rocket, reduces the propellant needed for exploration missions by a factor of 10. Currently plans include flight tests of a 200 kW VASIMR system, titled VF-200, on the International Space Station (ISS). The VF-200 will consist of two 100 kW thruster units packaged together in one engine bus. Each thruster core generates 27 kW of waste heat during its 15 minute firing time. The rocket core will be maintained between 283 and 573 K by a pumped thermal control loop. The design of a high temperature radiator is a unique challenge for the vehicle design. This paper will discuss the path taken to develop a steady state and transient-based radiator design. The paper will describe the radiator design option selected for the VASIMR thermal control system for use on ISS, and how the system relates to future exploration vehicles.

  16. Ultrahigh Specific Impulse Nuclear Thermal Propulsion

    SciTech Connect

    Anne Charmeau; Brandon Cunningham; Samim Anghaie

    2009-02-09

    Research on nuclear thermal propulsion systems (NTP) have been in forefront of the space nuclear power and propulsion due to their design simplicity and their promise for providing very high thrust at reasonably high specific impulse. During NERVA-ROVER program in late 1950's till early 1970's, the United States developed and ground tested about 18 NTP systems without ever deploying them into space. The NERVA-ROVER program included development and testing of NTP systems with very high thrust (~250,000 lbf) and relatively high specific impulse (~850 s). High thrust to weight ratio in NTP systems is an indicator of high acceleration that could be achieved with these systems. The specific impulse in the lowest mass propellant, hydrogen, is a function of square root of absolute temperature in the NTP thrust chamber. Therefor optimizing design performance of NTP systems would require achieving the highest possible hydrogen temperature at reasonably high thrust to weight ratio. High hydrogen exit temperature produces high specific impulse that is a diret measure of propellant usage efficiency.

  17. Hybrid-PIC Modeling of a High-Voltage, High-Specific-Impulse Hall Thruster

    NASA Technical Reports Server (NTRS)

    Smith, Brandon D.; Boyd, Iain D.; Kamhawi, Hani; Huang, Wensheng

    2013-01-01

    The primary life-limiting mechanism of Hall thrusters is the sputter erosion of the discharge channel walls by high-energy propellant ions. Because of the difficulty involved in characterizing this erosion experimentally, many past efforts have focused on numerical modeling to predict erosion rates and thruster lifespan, but those analyses were limited to Hall thrusters operating in the 200-400V discharge voltage range. Thrusters operating at higher discharge voltages (V(sub d) >= 500 V) present an erosion environment that may differ greatly from that of the lower-voltage thrusters modeled in the past. In this work, HPHall, a well-established hybrid-PIC code, is used to simulate NASA's High-Voltage Hall Accelerator (HiVHAc) at discharge voltages of 300, 400, and 500V as a first step towards modeling the discharge channel erosion. It is found that the model accurately predicts the thruster performance at all operating conditions to within 6%. The model predicts a normalized plasma potential profile that is consistent between all three operating points, with the acceleration zone appearing in the same approximate location. The expected trend of increasing electron temperature with increasing discharge voltage is observed. An analysis of the discharge current oscillations shows that the model predicts oscillations that are much greater in amplitude than those measured experimentally at all operating points, suggesting that the differences in oscillation amplitude are not strongly associated with discharge voltage.

  18. Europa Sample Return Mission Utilizing High Specific Impulse Propulsion Refueled with Indigenous Resources

    NASA Astrophysics Data System (ADS)

    Paniagua, J.; Powell, J. R.; Maise, G.

    2002-01-01

    We have conducted studies of a revolutionary new concept for conducting a Europa Sample Return Mission. Robotic spacecraft exploration of the Solar System has been severely constrained by the large energy requirements of interplanetary trajectories and the inherent delta V limitations of chemical rockets. Current missions use gravitational assists from intermediate planets to achieve these high-energy trajectories restricting payload size and increasing flight times. We propose a 6-year Europa Sample Return mission with very modest launch requirements enabled by MITEE. A new nuclear thermal propulsion engine design, termed MITEE (MIniature reacTor EnginE), has over twice the delta V capability of H2/O2 rockets (and much greater when refueled with H2 propellant from indigenous extraterrestrial resources) enabling unique missions that are not feasible with chemical propulsion. The MITEE engine is a compact, ultra-lightweight, thermal nuclear rocket that uses hydrogen as the propellant. MITEE, with its small size (50 cm O.D.), low mass (200 kg), and high specific impulse (~1000 sec), can provide a quantum leap in the capability for space science and exploration missions. The Robotic Europa Explorer (REE) spacecraft has a two-year outbound direct trajectory and lands on the satellite surface for an approximate 9 month stay. During this time, the vehicle is refueled with H2 propellant derived from Europa ice by the Autonomous Propellant Producer (APP), while collecting samples and searching for life. A small nuclear-heated submarine probe, the Autonomous Submarine Vehicle (ASV), based on MITEE technology, would melt through the ice and explore the undersea realm. The spacecraft has approximately a three year return to Earth after departure from Europa with samples onboard. Spacecraft payload is 430 kg at the start of the mission and can be launched with a single, conventional medium-sized Delta III booster. The spacecraft can bring back 25 kg of samples from Europa

  19. Specific Impulse Definition for Ablative Laser Propulsion

    NASA Technical Reports Server (NTRS)

    Herren, Kenneth A.; Gregory, Don A.

    2004-01-01

    The term "specific impulse" is so ingrained in the field of rocket propulsion that it is unlikely that any fundamental argument would be taken seriously for its removal. It is not an ideal measure but it does give an indication of the amount of mass flow (mass loss/time), as in fuel rate, required to produce a measured thrust over some time period This investigation explores the implications of being able to accurately measure the ablation rate and how the language used to describe the specific impulse results may have to change slightly, and recasts the specific impulse as something that is not a time average. It is not currently possible to measure the ablation rate accurately in real time so it is generally just assumed that a constant amount of material will be removed for each laser pulse delivered The specific impulse dependence on the ablation rate is determined here as a correction to the classical textbook definition.

  20. Specific Impulse Definition for Ablative Laser Propulsion

    NASA Technical Reports Server (NTRS)

    Herren, Kenneth A.; Gregory, Don A.

    2004-01-01

    The term "specific impulse" is so ingrained in the field of rocket propulsion that it is unlikely that any fundamental argument would be taken seriously for its removal. It is not an ideal measure but it does give an indication of the amount of mass flow (mass loss/time), as in fuel rate, required to produce a measured thrust over some time period This investigation explores the implications of being able to accurately measure the ablation rate and how the language used to describe the specific impulse results may have to change slightly, and recasts the specific impulse as something that is not a time average. It is not currently possible to measure the ablation rate accurately in real time so it is generally just assumed that a constant amount of material will be removed for each laser pulse delivered The specific impulse dependence on the ablation rate is determined here as a correction to the classical textbook definition.

  1. Specific Impulse and Mass Flow Rate Error

    NASA Technical Reports Server (NTRS)

    Gregory, Don A.

    2005-01-01

    Specific impulse is defined in words in many ways. Very early in any text on rocket propulsion a phrase similar to .specific impulse is the thrust force per unit propellant weight flow per second. will be found.(2) It is only after seeing the mathematics written down does the definition mean something physically to scientists and engineers responsible for either measuring it or using someone.s value for it.

  2. Recent Results From Internal and Very-Near-Field Plasma Diagnostics of a High Specific Impulse Hall Thruster

    NASA Technical Reports Server (NTRS)

    Hofer, Richard R.; Gallimore, Alec D.; Jacobson, David (Technical Monitor)

    2003-01-01

    Floating potential and ion current density measurements were taken on the laboratory model NASA-173Mv2 in order to improve understanding of the physical processes affecting Hall thruster performance at high specific impulse. Floating potential was measured on discharge chamber centerline over axial positions spanning 10 mm from the anode to 100 mm downstream of the exit plane. Ion current density was mapped radially up to 300 mm from thruster centerline over axial positions in the very-near-field (10 to 250 mm from the exit plane). All data were collected using a planar probe in conjunction with a high-speed translation stage to minimize probe-induced thruster perturbations. Measurements of floating potential at a xenon flow rate of 10 mg/s have shown that the acceleration layer moved upstream 3 1 mm when the voltage increased from 300 to 600 V. The length of the acceleration layer was 14 2 mm and was approximately constant with voltage and magnetic field. Ion current density measurements indicated the annular ion beam crossed the thruster centerline 163 mm downstream of the exit plane. Radial integration of the ion current density at the cathode plane provided an estimate of the ion current fraction. At 500 V and 5 mg/s, the ion current fraction was calculated as 0.77.

  3. Liquid Bismuth Propellant Management System for the Very High Specific Impulse Thruster with Anode Layer

    NASA Technical Reports Server (NTRS)

    Polzin, K. A.; Markusic, T. E.; Stanojev, B. J.

    2007-01-01

    Two prototype bismuth propellant feed systems were constructed and operated in conjunction with a propellant vaporizer. One system provided bismuth to a vaporizer using gas pressurization but did not include a means to measure the flow rate. The second system incorporated an electromagnetic pump to provide fine control of the hydrostatic pressure and a new type of in-line flow sensor that was developed for accurate, real-time measurement of the mass flow rate. High-temperature material compatibility was a driving design requirement for the pump and flow sensor, leading to the selection of Macor for the main body of both components. Posttest inspections of both components revealed no degradation of the material. The gas pressurization system demonstrated continuous pressure control over a range from zero to 200 torr. In separate proof-of-concept experiments, the electromagnetic pump produced a linear pressure rise as a function of current that compared favorably with theoretical pump pressure predictions, producing a pressure rise of 10 kPa at 30 A. Preliminary flow sensor operation indicated a bismuth flow rate of 6 mg/s with an uncertainty of plus or minus 6%. An electronics suite containing a real-time controller was successfully used to control the entire system, simultaneously monitoring all power supplies and performing data acquisition duties.

  4. Variable Specific Impulse Magnetoplasma Rocket Engine

    NASA Technical Reports Server (NTRS)

    Chang-Diaz, Franklin R. (Inventor)

    2002-01-01

    An engine is disclosed, including a controllable output plasma generator, a controllable heater for selectably raising a temperature of the plasma connected to an outlet of the plasma generator, and a nozzle connected to an outlet of the heater, through which heated plasma is discharged to provide thrust. In one embodiment, the source of plasma is a helicon generator. In one embodiment, the heater is an ion cyclotron resonator. In one embodiment, the nozzle is a radially diverging magnetic field disposed on a discharge side of the heater so that helically travelling particles in the beater exit the heater at high axial velocity. A particular embodiment includes control circuits for selectably directing a portion of radio frequency power from an RF generator to the helicon generator and to the cyclotron resonator so that the thrust output and the specific impulse of the engine can be selectively controlled. A method of propelling a vehicle is also disclosed. The method includes generating a plasma, heating said plasma, and discharging the heated plasma through a nozzle. In one embodiment, the nozzle is a diverging magnetic field. In this embodiment, the heating is performed by applying a radio frequency electro magnetic field to the plasma at the ion cyclotron frequency in an axially polarized DC magnetic field.

  5. Variable Specific Impulse Magnetoplasma Rocket Engine

    NASA Technical Reports Server (NTRS)

    Chang-Diaz, Franklin R. (Inventor)

    2002-01-01

    An engine is disclosed, including a controllable output plasma generator, a controllable heater for selectably raising a temperature of the plasma connected to an outlet of the plasma generator, and a nozzle connected to an outlet of the heater, through which heated plasma is discharged to provide thrust. In one embodiment, the source of plasma is a helicon generator. In one embodiment, the heater is an ion cyclotron resonator. In one embodiment, the nozzle is a radially diverging magnetic field disposed on a discharge side of the heater so that helically travelling particles in the beater exit the heater at high axial velocity. A particular embodiment includes control circuits for selectably directing a portion of radio frequency power from an RF generator to the helicon generator and to the cyclotron resonator so that the thrust output and the specific impulse of the engine can be selectively controlled. A method of propelling a vehicle is also disclosed. The method includes generating a plasma, heating said plasma, and discharging the heated plasma through a nozzle. In one embodiment, the nozzle is a diverging magnetic field. In this embodiment, the heating is performed by applying a radio frequency electro magnetic field to the plasma at the ion cyclotron frequency in an axially polarized DC magnetic field.

  6. The Influence of Current Density and Magnetic Field Topography in Optimizing the Performance, Divergence, and Plasma Oscillations of High Specific Impulse Hall Thrusters

    NASA Technical Reports Server (NTRS)

    Hofer, Richard R.; Jankovsky, Robert S.

    2003-01-01

    Recent studies of xenon Hall thrusters have shown peak efficiencies at specific impulses of less than 3000 s. This was a consequence of modern Hall thruster magnetic field topographies, which have been optimized for 300 V discharges. On-going research at the NASA Glenn Research Center is investigating this behavior and methods to enhance thruster performance. To conduct these studies, a laboratory model Hall thruster that uses a pair of trim coils to tailor the magnetic field topography for high specific impulse operation has been developed. The thruster-the NASA-173Mv2 was tested to determine how current density and magnetic field topography affect performance, divergence, and plasma oscillations at voltages up to 1000 V. Test results showed there was a minimum current density and optimum magnetic field topography at which efficiency monotonically increased with voltage. At 1000 V, 10 milligrams per second the total specific impulse was 3390 s and the total efficiency was 60.8%. Plume divergence decreased at 400-1000 V, but increased at 300-400 V as the result of plasma oscillations. The dominant oscillation frequency steadily increased with voltage, from 14.5 kHz at 300 V, to 22 kHz at 1000 V. An additional oscillatory mode in the 80-90 kHz frequency range began to appear above 500 V. The use of trim coils to modify the magnetic field improved performance while decreasing plume divergence and the frequency and magnitude of plasma oscillations.

  7. Effective specific impulse of external nuclear pulse propulsion systems

    NASA Technical Reports Server (NTRS)

    Reynolds, T. W.

    1972-01-01

    An investigation of a simple self-similar flow model for an external nuclear pulse propulsion system indicates that to achieve the high effective specific impulse of such a system three principal factors are required. The are (1) attaining pulses of optimum energy, (2) attaining good propellant collimation, and (3) using an ablative material for the pusher surface which has high absorptivity for radiant energy at the propellant stagnation temperature.

  8. Dimensions and disorder specificity of impulsivity in pathological gambling.

    PubMed

    Kräplin, Anja; Bühringer, Gerhard; Oosterlaan, Jaap; van den Brink, Wim; Goschke, Thomas; Goudriaan, Anna E

    2014-11-01

    Impulsivity is a core characteristic of pathological gambling (PG), even though the underlying structure and disorder specificity is unclear. This study aimed to explore different dimensions of impulsivity in a clinical sample including PG. Furthermore, we aimed to test which alterations of the impulsivity-related dimensions are disorder specific for PG. Participants were individuals diagnosed with PG (n=51) and two groups also characterized by various impulsive behaviors: an alcohol dependence (AD; n=45) and a Gilles de la Tourette syndrome (GTS; n=49) group. A healthy control (HC; n=53) group was recruited as comparison group. A comprehensive assessment was used including impulsivity-related and antipodal parameters of the Stop Signal Task, Stroop Task, Tower of London Task, Card Playing Task, Iowa Gambling Task and the Barratt Impulsiveness Scale-11. Principal axis factor analysis revealed four impulsivity-related dimensions that were labeled 'self-reported impulsivity', 'prepotent response impulsivity', 'choice impulsivity' and 'motor impulsivity'. The PG group scored significantly higher on all four dimensions compared to the HC group. In contrast, the PG group did not differ on any of the dimensions from the AD or the GTS group, except for 'choice impulsivity' where the PG group exhibited higher factor scores compared to the GTS group. Altogether, PG is associated with generally heightened impulsivity profiles compared to a HC group, which may be further used for intervention strategies. However, heightened scores in the impulsivity dimensions are not disorder specific for PG. Further research on shared or different underlying mechanisms of these overlapping impulsivity impairments is necessary. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. An Overview of the VHITAL Program: A Two-Stage Bismuth Fed Very High Specific Impulse Thruster with Anode Layer

    NASA Technical Reports Server (NTRS)

    Sengupta, Anita; Marrese-Reading, Colleen; Capelli, Mark; Scharfe, David; Tverdokhlebov, Sergey; Semenkin, Sasha; Tverdokhlebov, Oleg; Boyd, Ian; Keidar, Michael; Yalin, Azer; hide

    2005-01-01

    The Very High Isp Thruster with Anode Layer (VHITAL) is a two stage Hall thruster program that is a part of NASA's Prometheus Program in NASA's New Exploration Systems Mission Directorate (ESMD). It is a potentially viable low-cost alternative to ion engines for near-term NEP applications with the growth potential to support mid-term and far-term NEP missions... This paper will present an overview of the thruster fabrication, pre-existing TAL 160 demonstration, feed system development, lifetime assessment, contamination assessment, and mission study activities performed to date.

  10. An Overview of the VHITAL Program: A Two-Stage Bismuth Fed Very High Specific Impulse Thruster with Anode Layer

    NASA Technical Reports Server (NTRS)

    Sengupta, Anita; Marrese-Reading, Colleen; Capelli, Mark; Scharfe, David; Tverdokhlebov, Sergey; Semenkin, Sasha; Tverdokhlebov, Oleg; Boyd, Ian; Keidar, Michael; Yalin, Azer; Markusic, Tom; Polzin, Kurt

    2005-01-01

    The Very High Isp Thruster with Anode Layer (VHITAL) is a two stage Hall thruster program that is a part of NASA's Prometheus Program in NASA's New Exploration Systems Mission Directorate (ESMD). It is a potentially viable low-cost alternative to ion engines for near-term NEP applications with the growth potential to support mid-term and far-term NEP missions... This paper will present an overview of the thruster fabrication, pre-existing TAL 160 demonstration, feed system development, lifetime assessment, contamination assessment, and mission study activities performed to date.

  11. Overweight in adolescent, psychiatric inpatients: A problem of general or food-specific impulsivity?

    PubMed

    Deux, Natalie; Schlarb, Angelika A; Martin, Franziska; Holtmann, Martin; Hebebrand, Johannes; Legenbauer, Tanja

    2017-05-01

    Adolescent psychiatric patients are vulnerable to weight problems and show an overrepresentation of overweight compared to the healthy population. One potential factor that can contribute to the etiology of overweight is higher impulsivity. As of yet, it is unclear whether it is a general impulse control deficit or weight-related aspects such as lower impulse control in response to food that have an impact on body weight. As this may have therapeutic implications, the current study investigated differences between overweight and non-overweight adolescent psychiatric inpatients (N = 98; aged 12-20) in relation to trait impulsivity and behavioral inhibition performance. The Barratt Impulsiveness Scale and two go/no-go paradigms with neutral and food-related stimulus materials were applied. Results indicated no significant differences concerning trait impulsivity, but revealed that overweight inpatients had significantly more difficulties in inhibition performance (i.e. they reacted more impulsively) in response to both food and neutral stimuli compared to non-overweight inpatients. Furthermore, no specific inhibition deficit for high-caloric vs. low-caloric food cues emerged in overweight inpatients, whereas non-overweight participants showed significantly lower inhibition skills in response to high-caloric than low-caloric food stimuli. The results highlight a rather general, non-food-specific reduced inhibition performance in an overweight adolescent psychiatric population. Further research is necessary to enhance the understanding of the role of impulsivity in terms of body weight status in this high-risk group of adolescent inpatients.

  12. Domain-Specific Impulsivity in School-Age Children

    PubMed Central

    Tsukayama, Eli; Duckworth, Angela Lee; Kim, Betty

    2013-01-01

    Impulsivity is a salient individual difference in children with well-established predictive validity for life outcomes. The current investigation proposes that impulsive behaviors vary systematically by domain. In a series of studies with ethnically and socioeconomically diverse samples of middle school students, we find that schoolwork-related and interpersonal-related impulsivity, as observed by teachers, parents, and the students themselves, are distinct, moderately correlated behavioral tendencies. Each demonstrates differentiated relationships with dimensions of childhood temperament, Big Five personality factors, and outcomes, such as sociometric popularity, report card grades, and classroom conduct. Implications for theoretical conceptions of impulsivity as well as for practical applications (e.g., domain-specific interventions) are discussed. PMID:24118714

  13. Comparative High Voltage Impulse Measurement

    PubMed Central

    FitzPatrick, Gerald J.; Kelley, Edward F.

    1996-01-01

    A facility has been developed for the determination of the ratio of pulse high voltage dividers over the range from 10 kV to 300 kV using comparative techniques with Kerr electro-optic voltage measurement systems and reference resistive voltage dividers. Pulse voltage ratios of test dividers can be determined with relative expanded uncertainties of 0.4 % (coverage factor k = 2 and thus a two standard deviation estimate) or less using the complementary resistive divider/Kerr cell reference systems. This paper describes the facility and specialized procedures used at NIST for the determination of test voltage divider ratios through comparative techniques. The error sources and special considerations in the construction and use of reference voltage dividers to minimize errors are discussed, and estimates of the measurement uncertainties are presented. PMID:27805083

  14. Impulse Control, Diabetes-Specific Self-Efficacy, and Diabetes Management Among Emerging Adults With Type 1 Diabetes

    PubMed Central

    Hanna, Kathleen M.; Slaven, James E.; Weaver, Michael T.; Fortenberry, J. Dennis

    2013-01-01

    Objective To explore the relationships among impulse control, diabetes-specific self-efficacy, and diabetes management behaviors among emerging adults with type 1 diabetes. Methods A total of 204 high school seniors (M = 18.25 years, SD = .45, 55.9% females) with type 1 diabetes self-reported on impulse control, diabetes-specific self-efficacy, and diabetes management behaviors during the past 3 months. Mediation and path analyses were used to address aims. Results Greater impulse control was associated with better diabetes management among these emerging adults. In addition, diabetes-specific self-efficacy partially mediated the relationship between impulse control and diabetes management. Conclusions Impulse control and diabetes-specific self-efficacy may be important in the management of type 1 diabetes among emerging adults. Diabetes-specific self-efficacy may play an important role in successful diabetes management among youth with lower impulse control. PMID:23115219

  15. Sleep patterns and impulse control among Japanese junior high school students.

    PubMed

    Abe, Takeru; Hagihara, Akihito; Nobutomo, Koichi

    2010-10-01

    Adolescents with decreased impulse control exhibit behavioral problems. Lifestyles are related to impulse control. However, the relations of sleep patterns and impulse control among adolescents are unknown. Thus we examined how sleep patterns were associated with impulse control among Japanese junior high school students. Surveys were completed by a nationwide sample of 1934 students. A significant association between decreased impulse control and bedtimes after midnight was revealed. Specific lifestyle factors related to bedtimes after midnight were older age, greater numbers of hours spent watching television, lack of participation in an extracurricular activity, greater use of convenience stores, and increased attendance at cram schools. This study revealed that going to sleep after midnight was significantly related to decreased impulse control among adolescents. Data about specific lifestyle factors related to going to sleep after midnight should be useful in preventing those behaviors demonstrated by school children that derive from decreased impulse control.

  16. Specifics of signal generation in receivers based on thermoelastic effect at multiple impulse exposure

    NASA Astrophysics Data System (ADS)

    Shevnina, Elena I.; Maraev, Anton A.; Ishanin, Gennady G.

    2016-04-01

    To provide operating supervision of the process there is a need of means of control with high temporal stability and resistance to radiation excess. Receivers based on the thermoelastic effect in crystalline quartz are designed for energy measurement of lasers in single impulse mode or for average power measurement in operation monitoring of industrial lasers. In the research we analyze work of the receiver at single impulse exposure. The heat storage time of the receiver is defined. Specifics of signal generation in receivers on thermoelastic effect at multiple impulse exposure are also analyzed. An algorithm for voltage calculation of the receiver with given parameters is developed. The modelling shows that generated signal growth in the detector exposed to an impulse consequence can influence the power measurement result and thus the ways to reduce the effect are proposed.

  17. Sandia National Laboratories` high power electromagnetic impulse sources

    SciTech Connect

    Rinehart, L.F.; Buttram, M.T.; Denison, G.J.; Lundstrom, J.M.; Crowe, W.R.; Aurand, J.F.; Patterson, P.E.

    1994-10-01

    Three impulse sources have been developed to cover a wide range of peak power, bandwidth and center frequency requirements. Each of the sources can operate in single shot, rep-rate, or burst modes. These devices are of rugged construction and are suitable for field use. This paper will describe the specifications and principals of operation for each source. The sources to be described are: SNIPER (Sub-Nanosecond ImPulsE Radiator), a coaxial Blumlein pulser with an in-line (series) peaking switch; EMBL (EnantioMorphic BLurfflein), a bipolar parallel plate Blumlein with a crowbar type (parallel) peaking switch; and the LCO (L-C Oscillator) a spark-switched L-C oscillator with damped sinusoidal output. SNIPER and EMBL are ultra-wideband (UWB) sources which produce a very fast high voltage transition. When differentiated by the antenna, an impulse whose width corresponds to the transition time is radiated. The LCO operates with a center frequency up to 800 MHz and up to 100 MHz bandwidth. Because the LCO output is relatively narrow band, high gain antennas may be employed to produce very high radiated field strengths.

  18. Sandia National Laboratories' high power electromagnetic impulse sources

    NASA Astrophysics Data System (ADS)

    Rinehart, L. F.; Buttram, M. T.; Denison, G. J.; Lundstrom, J. M.; Crowe, W. R.; Aurand, J. F.; Patterson, P. E.

    1994-05-01

    Three impulse sources have been developed to cover a wide range of peak power, bandwidth and center frequency requirements. Each of the sources can operate in single shot, rep-rate, or burst modes. These devices are of rugged construction and are suitable for field use. This paper will describe the specifications and principals of operation for each source. The sources to be described are: SNIPER (Sub-Nanosecond ImPulsE Radiator), a coaxial Blumlein pulser with an in-line (series) peaking switch; EMBL (EnantioMorphic BLurfflein), a bipolar parallel plate Blumlein with a crowbar type (parallel) peaking switch; and the LCO (L-C Oscillator) a spark-switched L-C oscillator with damped sinusoidal output. SNIPER and EMBL are ultra-wideband (UWB) sources which produce a very fast high voltage transition. When differentiated by the antenna, an impulse whose width corresponds to the transition time is radiated. The LCO operates with a center frequency up to 800 MHz and up to 100 MHz bandwidth. Because the LCO output is relatively narrow band, high gain antennas may be employed to produce very high radiated field strengths.

  19. High power impulse magnetron sputtering discharge

    SciTech Connect

    Gudmundsson, J. T.; Brenning, N.; Lundin, D.; Helmersson, U.

    2012-05-15

    The high power impulse magnetron sputtering (HiPIMS) discharge is a recent addition to plasma based sputtering technology. In HiPIMS, high power is applied to the magnetron target in unipolar pulses at low duty cycle and low repetition frequency while keeping the average power about 2 orders of magnitude lower than the peak power. This results in a high plasma density, and high ionization fraction of the sputtered vapor, which allows better control of the film growth by controlling the energy and direction of the deposition species. This is a significant advantage over conventional dc magnetron sputtering where the sputtered vapor consists mainly of neutral species. The HiPIMS discharge is now an established ionized physical vapor deposition technique, which is easily scalable and has been successfully introduced into various industrial applications. The authors give an overview of the development of the HiPIMS discharge, and the underlying mechanisms that dictate the discharge properties. First, an introduction to the magnetron sputtering discharge and its various configurations and modifications is given. Then the development and properties of the high power pulsed power supply are discussed, followed by an overview of the measured plasma parameters in the HiPIMS discharge, the electron energy and density, the ion energy, ion flux and plasma composition, and a discussion on the deposition rate. Finally, some of the models that have been developed to gain understanding of the discharge processes are reviewed, including the phenomenological material pathway model, and the ionization region model.

  20. Experimental validation of single pass ion cyclotron resonance absorption in a high speed flowing plasma applied to the variable specific impulse magnetoplasma rocket (VASIMR)

    NASA Astrophysics Data System (ADS)

    Davis, Christopher Nelson

    The topic of this thesis is the experimental characterization and analysis of single pass ion cyclotron resonance heating as applied to acceleration of ions for electric propulsion. The experimental work was done on the VX-10 experiment of the VASIMR (Variable Specific Impulse Magnetoplasma Rocket) concept. In ion cyclotron resonance heating (ICRH) a RF wave is launched into a magnetized plasma where it then accelerates the ions by increasing their rotational speed around the magnetic field lines. The electric field vector of the right hand component of the wave will rotate around the field lines with a frequency oRF in the same direction as the ion's cyclotron motion about the field lines. Consequently, when oRF ≈ oci (where oci is the ion's cyclotron frequency) the force from the electric field of the wave on the ions will result in a continuous rotational energy gain. The perpendicular velocity of the ions generated by ICRH is then converted into axial velocity by the decreasing gradient of the axial magnetic field at the exhaust of the propulsion system from conservation of the magnet moment. This increase in axial velocity is predicted to cause a decrease in density due to conservation of current in the plasma. In order to characterize this density drop during ion cyclotron heating, a single channel interferometer system was developed and implemented on the VX-10. Interferometer density measurements were taken at three different locations on the VX-10 experiment upstream and downstream of the ion acceleration zone. Measurements were made of the density drop in both Helium and Deuterium plasma discharges during ICRH under a variety of operating conditions including magnetic field profile, gas flow rate and ICRH power pulse timing, and ICRH power. A clear measurement of a density drop was observed downstream of the ion resonance zone characteristic of ion acceleration and measurement of little change in density upstream of the resonance zone where no

  1. Reactive high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gudmundsson, J. T.; Magnus, F.; Tryggvason, T. K.; Sveinsson, O. B.; Olafsson, S.

    2012-10-01

    Here we discuss reactive high power impulse magnetron sputtering sputtering (HiPIMS) [1] of Ti target in an Ar/N2 and Ar/O2 atmosphere. The discharge current waveform is highly dependent on both the pulse repetition frequency and discharge voltage. The discharge current increases with decreasing frequency or voltage. This we attribute to an increase in the secondary electron emission yield during the self-sputtering phase of the pulse, as nitride [2] or oxide [3] forms on the target. We also discuss the growth of TiN films on SiO2 at temperatures of 22-600 ^oC. The HiPIMS process produces denser films at lower growth temperature and the surface is much smoother and have a significantly lower resistivity than dc magnetron sputtered films on SiO2 at all growth temperatures due to reduced grain boundary scattering [4].[4pt] [1] J. T. Gudmundsson, N. Brenning, D. Lundin and U. Helmersson, J. Vac. Sci. Technol. A, 30 030801 (2012)[0pt] [2] F. Magnus, O. B. Sveinsson, S. Olafsson and J. T. Gudmundsson, J. Appl. Phys., 110 083306 (2011)[0pt] [3] F. Magnus, T. K. Tryggvason, S. Olafsson and J. T. Gudmundsson, J. Vac. Sci. Technol., submitted 2012[0pt] [4] F. Magnus, A. S. Ingason, S. Olafsson and J. T. Gudmundsson, IEEE Elec. Dev. Lett., accepted 2012

  2. Domain-Specific Impulsivity in School-Age Children

    ERIC Educational Resources Information Center

    Tsukayama, Eli; Duckworth, Angela Lee; Kim, Betty

    2013-01-01

    Impulsivity is a salient individual difference in children with well-established predictive validity for life outcomes. The current investigation proposes that impulsive behaviors vary systematically by domain. In a series of studies with ethnically and socioeconomically diverse samples of middle school students, we find that schoolwork-related…

  3. Domain-Specific Impulsivity in School-Age Children

    ERIC Educational Resources Information Center

    Tsukayama, Eli; Duckworth, Angela Lee; Kim, Betty

    2013-01-01

    Impulsivity is a salient individual difference in children with well-established predictive validity for life outcomes. The current investigation proposes that impulsive behaviors vary systematically by domain. In a series of studies with ethnically and socioeconomically diverse samples of middle school students, we find that schoolwork-related…

  4. A path model of different forms of impulsivity with externalizing and internalizing psychopathology: Towards greater specificity.

    PubMed

    Johnson, Sheri L; Tharp, Jordan A; Peckham, Andrew D; Carver, Charles S; Haase, Claudia M

    2017-09-01

    A growing empirical literature indicates that emotion-related impulsivity (compared to impulsivity that is unrelated to emotion) is particularly relevant for understanding a broad range of psychopathologies. Recent work, however, has differentiated two forms of emotion-related impulsivity: A factor termed Pervasive Influence of Feelings captures tendencies for emotions (mostly negative emotions) to quickly shape thoughts, and a factor termed Feelings Trigger Action captures tendencies for positive and negative emotions to quickly and reflexively shape behaviour and speech. This study used path modelling to consider links from emotion-related and non-emotion-related impulsivity to a broad range of psychopathologies. Undergraduates completed self-report measures of impulsivity, depression, anxiety, aggression, and substance use symptoms. A path model (N = 261) indicated specificity of these forms of impulsivity. Pervasive Influence of Feelings was related to anxiety and depression, whereas Feelings Trigger Action and non-emotion-related impulsivity were related to aggression and substance use. The findings of this study suggest that emotion-relevant impulsivity could be a potentially important treatment target for a set of psychopathologies. Recent work has differentiated two forms of emotion-related impulsivity. This study tests a multivariate path model linking emotion-related and non-emotion-related impulsivity with multiple forms of psychopathology. Impulsive thoughts in response to negative emotions were related to anxiety and depression. Impulsive actions in response to emotions were related to aggression and substance use, as did non-emotion-related impulsivity. The study was limited by the reliance on self-report measures of impulsivity and psychopathology. There is a need for longitudinal work on how these forms of impulsivity predict the onset and course of psychopathology. © 2017 The British Psychological Society.

  5. High-intensity drying processes: Impulse drying. Annual report

    SciTech Connect

    Orloff, D.I.; Phelan, P.M.

    1993-12-01

    Experiments were conducted on a sheet-fed pilot-scale shoe press to compare impulse drying and double-felted pressing. Both an IPST (Institute of Paper Science and Technology) ceramic coated and Beloit Type A press roll were evaluated for lienrboard sheet structures having a wide range of z-direction permeability. Purpose was to find ways of correcting sheet sticking problems observed in previous pilot-scale shoe press experiments. Results showed that impulse drying was superior to double felted pressing in both press dryness and in important paper physical properties. Impulse drying critical temperature was found to depend on specific surface of the heated layer of the sheet, thermal properties of the press roll surface, and choice of felt. Impulse drying of recycled and two-ply liner was demonstrated for both Southern Pile and Douglas fir-containing furnishes.

  6. Liquid Engine Design: Effect of Chamber Dimensions on Specific Impulse

    NASA Technical Reports Server (NTRS)

    Hoggard, Lindsay; Leahy, Joe

    2009-01-01

    Which assumption of combustion chemistry - frozen or equilibrium - should be used in the prediction of liquid rocket engine performance calculations? Can a correlation be developed for this? A literature search using the LaSSe tool, an online repository of old rocket data and reports, was completed. Test results of NTO/Aerozine-50 and Lox/LH2 subscale and full-scale injector and combustion chamber test results were found and studied for this task. NASA code, Chemical Equilibrium with Applications (CEA) was used to predict engine performance using both chemistry assumptions, defined here. Frozen- composition remains frozen during expansion through the nozzle. Equilibrium- instantaneous chemical equilibrium during nozzle expansion. Chamber parameters were varied to understand what dimensions drive chamber C* and Isp. Contraction Ratio is the ratio of the nozzle throat area to the area of the chamber. L is the length of the chamber. Characteristic chamber length, L*, is the length that the chamber would be if it were a straight tube and had no converging nozzle. Goal: Develop a qualitative and quantitative correlation for performance parameters - Specific Impulse (Isp) and Characteristic Velocity (C*) - as a function of one or more chamber dimensions - Contraction Ratio (CR), Chamber Length (L ) and/or Characteristic Chamber Length (L*). Determine if chamber dimensions can be correlated to frozen or equilibrium chemistry.

  7. Mission maps for use in the choice of specific impulse for manned Mars missions

    SciTech Connect

    Madsen, W.W.; Neuman, J.E.; Olson, T.S.; Siahpush, A.S.

    1991-01-01

    The choice of engine concept for the initial manned missions to Mars should be driven by what can be feasibly built and flight qualified in the near term, and by the level of engine performance that is required for these missions. This paper addresses how mission requirements affect the choice of specific impulse, and consequently what values of the specific impulse best serve these missions. Broad mission surveys and sensitivity studies were performed to determine the specific impulse values that allow for fast transfer times and wide launch windows. We find that a specific impulse of around 1000 to 1200 sec is sufficient. Choosing an engine concept that has a higher specific impulse value is not justified for these missions because the modest reduction in propellant requirements and further widening of the launch windows does not compensate for the substantially greater technical risk. 3 refs., 8 figs.

  8. Assessment of Community Response to High-Energy Impulsive Sounds

    DTIC Science & Technology

    1981-07-01

    10M --0 -- f·· ’ " .. ~’ 82. ol o~l41 ASSESSIENT OF COMMUNITY RESPONSE ( TO HIGH - ENERGY IMPtLSIVE SOUNDS Report of Working Group 84 Committee on...SOUNDS 4 SUBJECTIVE RESPONSE TO HIGH - ENERGY IMPULSIVE SOUNDS 5 SOUND LEVEL-WEIGHTED POPULATION 17 LAND-USE PLANNINC FOR COMBINED ENVIRONMENTS 18...Listening 13 4 Recomhmended Relationships for Predicting Coummunity Response to High - Energy Impulsive Sounds and to Other Sounds 15 ix MOuOM PA 60LN UM

  9. Amphetamine Conditioned Place Preference in High and Low Impulsive Rats

    PubMed Central

    Yates, Justin R.; Marusich, Julie A.; Gipson, Cassandra D.; Beckmann, Joshua S.; Bardo, Michael T.

    2011-01-01

    Stimulants such as d-amphetamine (AMPH) are used commonly to treat attention-deficit hyperactivity disorder (ADHD), but concerns have been raised regarding the use of AMPH due to its reinforcing and potentially addictive properties. The current study examined if individual differences in impulsive choice predict AMPH-induced hyperactivity and conditioned place preference (CPP). Rats were first tested in delay discounting using an adjusting delay procedure to measure impulsive choice and then were subsequently tested for AMPH CPP. High impulsive (HiI) and low impulsive (LoI) rats were conditioned across four sessions with 0.1, 0.5, or 1.5 mg/kg of AMPH. AMPH increased locomotor activity for HiI and LoI rats following 0.5 mg/kg but failed to increase activity following 0.1 and 1.5 mg/kg. CPP was established for HiI rats with both 0.5 and 1.5 mg/kg of AMPH, whereas LoI rats did not develop CPP following any dose of AMPH; HiI and LoI groups differed significantly following 0.5 mg/kg of AMPH. These results indicate that HiI rats are more sensitive to the rewarding effects of AMPH compared to LoI rats, which is consistent with research showing that high impulsive individuals may be more vulnerable to stimulant abuse. PMID:21807020

  10. Direct measurement method of specific impulse for pulse laser ablation micro-propulsion

    NASA Astrophysics Data System (ADS)

    Zhou, Weijing; Jin, Xing; Chang, Hao

    2017-05-01

    Laser ablation micro-propulsion technology is the most promising field in laser propulsion. The specific impulse is the important evaluate indicator of the micro propulsion performance. It represents the impulse generation by consuming unit weight of the working medium. Its accurate measurement can not only help to analyze the mechanism of laser ablation matter, but also help the design of micro laser ablation thruster. This paper presents a measurement method, which can not only obtain the impulse by single pulsed laser ablation the working medium, but also measure the ablation mass, which can directly measure the specific impulse. The method is based on the model of torsion pendulum in vertical direction movement, which is the direction of impulse by pulsed laser ablation and the gravitation direction caused by the loss of the ablation mass, to obtain the corresponding impulse and ablative weight. The paper deduced the measuring principle, pointed out the error and analysed the design principle of the torsion balance, the results show that, according to the torsion angle change due to the impulse by pulsed laser ablation and the mass loss by laser ablation, the maximum angle can be used to calculate the impulse and the stable rotation angle can be used to calculate the loss weight when the torsion period is much greater than four times the width of a single pulse.

  11. Attentional bias toward high-calorie food-cues and trait motor impulsivity interactively predict weight gain

    PubMed Central

    Meule, Adrian; Platte, Petra

    2016-01-01

    Strong bottom-up impulses and weak top-down control may interactively lead to overeating and, consequently, weight gain. In the present study, female university freshmen were tested at the start of the first semester and again at the start of the second semester. Attentional bias toward high- or low-calorie food-cues was assessed using a dot-probe paradigm and participants completed the Barratt Impulsiveness Scale. Attentional bias and motor impulsivity interactively predicted change in body mass index: motor impulsivity positively predicted weight gain only when participants showed an attentional bias toward high-calorie food-cues. Attentional and non-planning impulsivity were unrelated to weight change. Results support findings showing that weight gain is prospectively predicted by a combination of weak top-down control (i.e. high impulsivity) and strong bottom-up impulses (i.e. high automatic motivational drive toward high-calorie food stimuli). They also highlight the fact that only specific aspects of impulsivity are relevant in eating and weight regulation. PMID:28070402

  12. Attentional bias toward high-calorie food-cues and trait motor impulsivity interactively predict weight gain.

    PubMed

    Meule, Adrian; Platte, Petra

    2016-01-01

    Strong bottom-up impulses and weak top-down control may interactively lead to overeating and, consequently, weight gain. In the present study, female university freshmen were tested at the start of the first semester and again at the start of the second semester. Attentional bias toward high- or low-calorie food-cues was assessed using a dot-probe paradigm and participants completed the Barratt Impulsiveness Scale. Attentional bias and motor impulsivity interactively predicted change in body mass index: motor impulsivity positively predicted weight gain only when participants showed an attentional bias toward high-calorie food-cues. Attentional and non-planning impulsivity were unrelated to weight change. Results support findings showing that weight gain is prospectively predicted by a combination of weak top-down control (i.e. high impulsivity) and strong bottom-up impulses (i.e. high automatic motivational drive toward high-calorie food stimuli). They also highlight the fact that only specific aspects of impulsivity are relevant in eating and weight regulation.

  13. Impulsivity, aggression and brain structure in high and low lethality suicide attempters with borderline personality disorder

    PubMed Central

    Soloff, Paul; White, Richard; Diwadkar, Vaibhav A.

    2014-01-01

    Impulsivity and aggressiveness are trait dispositions associated with the vulnerability to suicidal behavior across diagnoses. They are associated with structural and functional abnormalities in brain networks involved in regulation of mood, impulse and behavior. They are also core characteristics of borderline personality disorder (BPD), a disorder defined, in part, by recurrent suicidal behavior. We assessed the relationships between personality traits, brain structure and lethality of suicide attempts in 51 BPD attempters using multiple regression analyses on structural MRI data. BPD was diagnosed by the Diagnostic Interview for Borderline Patients-revised, impulsivity by the Barratt Impulsiveness Scale (BIS), aggression by the Brown-Goodwin Lifetime History of Aggression (LHA), and high lethality by a score of 4 or more on the Lethality Rating Scale (LRS). Sixteen High Lethality attempters were compared to 35 Low Lethality attempters, with no significant differences noted in gender, co-morbidity, childhood abuse, BIS or LHA scores. Degree of medical lethality (LRS) was negatively related to gray matter volumes across multiple fronto-temporal-limbic regions. Effects of impulsivity and aggression on gray matter volumes discriminated High from Low Lethality attempters and differed markedly within lethality groups. Lethality of suicide attempts in BPD may be related to the mediation of these personality traits by specific neural networks. PMID:24656768

  14. Impulsivity, aggression and brain structure in high and low lethality suicide attempters with borderline personality disorder.

    PubMed

    Soloff, Paul; White, Richard; Diwadkar, Vaibhav A

    2014-06-30

    Impulsivity and aggressiveness are trait dispositions associated with the vulnerability to suicidal behavior across diagnoses. They are associated with structural and functional abnormalities in brain networks involved in regulation of mood, impulse and behavior. They are also core characteristics of borderline personality disorder (BPD), a disorder defined, in part, by recurrent suicidal behavior. We assessed the relationships between personality traits, brain structure and lethality of suicide attempts in 51 BPD attempters using multiple regression analyses on structural MRI data. BPD was diagnosed by the Diagnostic Interview for Borderline Patients-revised, impulsivity by the Barratt Impulsiveness Scale (BIS), aggression by the Brown-Goodwin Lifetime History of Aggression (LHA), and high lethality by a score of 4 or more on the Lethality Rating Scale (LRS). Sixteen High Lethality attempters were compared to 35 Low Lethality attempters, with no significant differences noted in gender, co-morbidity, childhood abuse, BIS or LHA scores. Degree of medical lethality (LRS) was negatively related to gray matter volumes across multiple fronto-temporal-limbic regions. Effects of impulsivity and aggression on gray matter volumes discriminated High from Low Lethality attempters and differed markedly within lethality groups. Lethality of suicide attempts in BPD may be related to the mediation of these personality traits by specific neural networks. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  15. High impulsivity as a risk factor for the development of internalizing disorders in detained juvenile offenders.

    PubMed

    Zhou, Jiansong; Witt, Katrina; Chen, Chen; Zhang, Simei; Zhang, Yingdong; Qiu, Changjian; Cao, Liping; Wang, Xiaoping

    2014-07-01

    Whilst impulsivity is most commonly linked to the development of internalizing disorders, high levels of impulsivity, anxiety, and depression have been found in detained juvenile offenders. We therefore sought to determine whether impulsivity is associated with the development of self-reported anxiety or depression in a sample of detained juvenile offenders. 323 male juvenile offenders and 86 typically developing controls, aged 15-17 were assessed. The Schedule for Affective Disorder and Schizophrenia for School-Age Children Present and Lifetime (SADS-PL) was used to assess psychiatric diagnoses, the Barratt Impulsivity Scale (BIS-11) was used to measure impulsivity, and the Screen for Child Anxiety Related Emotional Disorders (SCARED) and the Birleson Depression Self-Rating Scale (DSRS) were used to assess self-reported anxiety and depression respectively. Compared to controls, juvenile offenders had significantly higher scores on the BIS-11 total, as well as on the motor and nonplanning subscales (all p values <0.001), as well as higher DSRS (p<0.001) and SCARED (p<0.05) scores. Within the juvenile offender group, scores on the SCARED correlated positively with BIS-11 total, attention subscale, motor subscale, and total DSRS (all p values <0.01). DSRS scores correlated positively with BIS-11 total, attention subscale, nonplanning subscale, and total SCARED scores (all p values <0.01). Participants were then categorized low, middle or high impulsivity according to scores on the BIS-11. One-way ANOVAs demonstrated a significant difference between these tertiles on DSRS [F(2,320)=4.862, p<0.05] and SCARED total scores [F(2,320)=3.581, p<0.05]. Specifically, post-hoc analyses found that the high impulsivity tertile scored significant higher than the remaining tertiles on both DSRS (16.1 ± 0.3 vs. 14.0 ± 0.6, p<0.05) and SCARED (23.3 ± 0.9 vs. 18.4 ± 1.4, p<0.05) scores. Using multiple linear regression, BIS-11 attention scores, number of months served in custody

  16. Method and apparatus for improved high power impulse magnetron sputtering

    DOEpatents

    Anders, Andre

    2013-11-05

    A high power impulse magnetron sputtering apparatus and method using a vacuum chamber with a magnetron target and a substrate positioned in the vacuum chamber. A field coil being positioned between the magnetron target and substrate, and a pulsed power supply and/or a coil bias power supply connected to the field coil. The pulsed power supply connected to the field coil, and the pulsed power supply outputting power pulse widths of greater that 100 .mu.s.

  17. High-definition tDCS alters impulsivity in a baseline-dependent manner.

    PubMed

    Shen, Bo; Yin, Yunlu; Wang, Jiashu; Zhou, Xiaolin; McClure, Samuel M; Li, Jian

    2016-12-01

    In intertemporal choice (ITC), people discount future rewards in proportion to the time delay until reward receipt. Despite recent non-invasive brain stimulation studies suggesting a general causal link between dorsolateral prefrontal cortex (dlPFC) activity and ITC impulsivity, results regarding the functional specificity of dlPFC are mixed. We used high-definition transcranial direct current stimulation (HD-tDCS) to map changes in causal impulsivity through bi-directional modulation of left and right dlPFC during ITC. Model-free and model-based analyses demonstrated that anodal and cathodal stimulation of left dlPFC, but not right dlPFC, decreased and increased impulsivity, respectively. Critically, an individual differences analysis revealed that modulation of impulsivity was contingent on participants' baseline impulsivity. Overall, our results might reconcile the discrepancies in the existing literature and suggest a baseline-dependent role for left dlPFC during ITC. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  18. Impulsive sensation seeking, binge drinking, and alcohol-related consequences: Do protective behavioral strategies help high risk adolescents?

    PubMed

    Doumas, Diana M; Miller, Raissa; Esp, Susan

    2017-01-01

    This study examined protective behavioral strategies (PBS) as a moderator of the relationship between impulsive sensation seeking and binge drinking and alcohol-related consequences in a sample of high school seniors (N=346). Hierarchical regression analyses indicated that impulsive sensation seeking was a significant predictor of binge drinking and alcohol-related consequences and that PBS moderated these relationships. Specifically, manner of drinking moderated the relationships such that among students with high impulsive sensation seeking, those using strategies related to how they drink (e.g. avoiding rapid and excessive drinking) reported lower levels of binge drinking and alcohol-related consequences than those using fewer of these strategies. Clinical implications are discussed including using personality-targeted interventions that equip high impulsive sensation seeking adolescents with specific strategies to reduce binge drinking and alcohol-related consequences.

  19. Hybrid antenna sources for radiating high-power impulsive fields

    NASA Astrophysics Data System (ADS)

    Buchenauer, C. Jerald; Marek, J. Raley

    1995-09-01

    The transmission of impulsive signals through baluns and feed lines, between high-power, fast-risetime pulse generators and impulse-radiating antennas, leads to degraded system performance and increased pulse risetime due to transit-time dispersion, skin and dielectric losses, and electrical breakdown effects. These loss mechanisms are greatly reduced in system designs that eliminate feed lines and baluns by combining the antenna and generator in a single hybrid device that is compact, simple, and robust. This paper describes generators in which the antenna itself is pulse charged to hundreds of kV and subsequently shorted at the feed point by an oil spark switch. These Hertzian generators maintain conical symmetry to within a few millimeters of the feed-point switch, thus providing conditions for launching near-ideal spherical TEM step waves for driving impulse-radiating, focused-aperture antennas. Careful attention to symmetry, optical principles, and precise methods of measurement has yielded subnanosecond pulse risetimes that are more than ten times faster than predictions from spark- switch scaling laws.

  20. High harmonic generation from impulsively aligned SO2

    NASA Astrophysics Data System (ADS)

    Devin, Julien; Wang, Song; Kaldun, Andreas; Bucksbaum, Phil

    2016-05-01

    Previous work in high harmonics generation (HHG) in aligned molecular gases has mainly focused on rotational dynamics in order to determine the contributions of different orbitals to the ionization step. In our experiment, we focus on the shorter timescale of vibrational dynamics. We generate high harmonics from impulsively aligned SO2 molecules in a gas jet and record the emitted attosecond pulse trains in a home-built high resolution vacuum ultra violet (VUV) spectrometer. Using the high temporal resolution of our setup, we are able to map out the effects of vibrational wavepackets with a sub-femtosecond resolution. The target molecule, SO2 gas, is impulsively aligned by a near-infrared laser pulse and has accessible vibrations on the timescale of the short laser pulse used. We present first experimental results for the response to this excitation in high-harmonics. We observe both fast oscillations in the time domain as well as shifts of the VUV photon energy outside of the pulse overlaps. Research supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), Chemical Sciences, Geosciences, and Biosciences Division and by the National Science Foundation Graduate Research Fellowship.

  1. Discharge current modes of high power impulse magnetron sputtering

    SciTech Connect

    Wu, Zhongzhen Xiao, Shu; Ma, Zhengyong; Cui, Suihan; Ji, Shunping; Pan, Feng; Tian, Xiubo; Fu, Ricky K. Y.; Chu, Paul K.

    2015-09-15

    Based on the production and disappearance of ions and electrons in the high power impulse magnetron sputtering plasma near the target, the expression of the discharge current is derived. Depending on the slope, six possible modes are deduced for the discharge current and the feasibility of each mode is discussed. The discharge parameters and target properties are simplified into the discharge voltage, sputtering yield, and ionization energy which mainly affect the discharge plasma. The relationship between these factors and the discharge current modes is also investigated.

  2. Advanced concepts. [specific impulse, mass drivers, electromagnetic launchers, and the rail gun

    NASA Technical Reports Server (NTRS)

    Banks, B. A.

    1980-01-01

    The relative strengths of those interactions which enable propulsive forces are listed as well as the specific impulse of various propellants. Graphics show the linear synchronous motor of the mass driver, the principle of the direct current electromagnetic launcher, and the characteristics of the rail gun.

  3. High resolution imaging with impulse based thermoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Kellnberger, Stephan; Hajiaboli, Amir; Sergiadis, George; Razansky, Daniel; Ntziachristos, Vasilis

    2011-07-01

    Existing imaging modalities like microwave- or radiofrequency (RF) induced thermoacoustic tomography systems show the potential for resolving structures deep inside tissue due to the high penetration properties of RF. However, one of the major drawbacks of existing thermoacoustic tomography systems with pulse modulated carrier frequency excitation is the compromise between efficient signal generation and attainable spatial resolution. In order to overcome limitations of conventional thermoacoustic imaging methods, we herein present and experimentally validate our novel approach towards high resolution thermoacoustic tomography. Instead of carrier-frequency amplification, we utilize ultrahigh-energy electromagnetic impulses at nanosecond duration with near-field energy coupling, thus maintaining thermoacoustic signal strength without compromising spatial resolution. Preliminary experiments on highly absorbing objects, consisting of copper wires with characteristic sizes of ~100 μm, reveal the resolution performance which yields 160 μm. Furthermore, benefits like its cost effectiveness, simplicity and compactness with the potential application in small animal imaging as well as human body imaging show that thermoacoustic tomography with impulse excitation is a promising imaging modality which has a broad range of applications.

  4. Impulse control and restrained eating among young women: Evidence for compensatory cortical activation during a chocolate-specific delayed discounting task.

    PubMed

    Dong, Debo; Wang, Yulin; Jackson, Todd; Chen, Shuaiyu; Wang, Yu; Zhou, Feng; Chen, Hong

    2016-10-01

    Theory and associated research indicate that people with elevated restrained eating (RE) scores have higher risk for binge eating, future bulimic symptom onset and weight gain. Previous imaging studies have suggested hyper-responsive reward brain area activation in response to food cues contributes to this risk but little is known about associated neural impulse control mechanisms, especially when considering links between depleted cognitive resources related to unsuccessful RE. Towards illuminating this issue, we used a chocolate-specific delayed discounting (DD) task to investigate relations between RE scores, behavior impulsivity, and corresponding neural impulse control correlates in a functional magnetic resonance imaging (fMRI) study of 27 young women. Specifically, participants were required to choose between more immediate, smaller versus delayed, larger hypothetical chocolate rewards following initial consumption of a chocolate. As predicted, RE scores were correlated positively with behavior impulse control levels. More critically, higher RE scores were associated with stronger activation in impulse control region, the dorsal-lateral prefrontal cortex (DLPFC) during the completion of difficult decision trials reflecting higher cognitive demands and resource depletion relative to easy decision trials. Exploratory analyses revealed a positive correlation between RE scores and activity in a reward system hub, the right striatum. Moreover, a positive correlation between left DLPFC and striatum activation was posited to reflect, in part, impulse control region compensation in response to stronger reward signal among women with RE elevations. Findings suggested impulse control lapses may contribute to difficulties in maintaining RE, particularly when cognitive demands are high.

  5. Dysfunctional decision-making in pathological gambling: pattern specificity and the role of impulsivity.

    PubMed

    Kräplin, Anja; Dshemuchadse, Maja; Behrendt, Silke; Scherbaum, Stefan; Goschke, Thomas; Bühringer, Gerhard

    2014-03-30

    Dysfunctional decision-making in individuals with pathological gambling (PGs) may result from dominating reward-driven processes, indicated by higher impulsivity. In the current study we examined (1) if PGs show specific decision-making impairments related to dominating reward-driven processes rather than to strategic planning deficits and (2) whether these impairments are related to impulsivity. Nineteen PGs according to DSM-IV and 19 matched control subjects undertook the Cambridge Gambling Task (CGT) to assess decision-making. The delay discounting paradigm (DDP) as well as the UPPS Impulsive Behavior Scale (measuring urgency, premeditation, perseverance and sensation seeking) were administered as multidimensional measures of impulsivity. Results revealed that (1) PGs exhibited higher risk seeking and an immediate reward focus in the CGT and, in contrast, comparable strategic planning to the control group. (2) Decision-making impairments were related to more severe delay discounting and, specifically, to increased urgency and less premeditation. Our findings suggest (1) the necessity to disentangle decision-making components in order to improve etiological models of PGs, and (2) that urgency and premeditation are specifically related to disadvantageous decision-making and should be tackled in intervention strategies focusing on emotion tolerance and control strategies. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  6. Very low pressure high power impulse triggered magnetron sputtering

    DOEpatents

    Anders, Andre; Andersson, Joakim

    2013-10-29

    A method and apparatus are described for very low pressure high powered magnetron sputtering of a coating onto a substrate. By the method of this invention, both substrate and coating target material are placed into an evacuable chamber, and the chamber pumped to vacuum. Thereafter a series of high impulse voltage pulses are applied to the target. Nearly simultaneously with each pulse, in one embodiment, a small cathodic arc source of the same material as the target is pulsed, triggering a plasma plume proximate to the surface of the target to thereby initiate the magnetron sputtering process. In another embodiment the plasma plume is generated using a pulsed laser aimed to strike an ablation target material positioned near the magnetron target surface.

  7. High Voltage Discharge Profile on Soil Breakdown Using Impulse Discharge

    NASA Astrophysics Data System (ADS)

    Fajingbesi, F. E.; Midi, N. S.; Elsheikh, E. M. A.; Yusoff, S. H.

    2017-06-01

    Grounding terminals are mandatory in electrical appliance design as they provide safety route during overvoltage faults. The soil (earth) been the universal ground is assumed to be at zero electric potential. However, due to properties like moisture, pH and available nutrients; the electric potential may fluctuate between positive and negative values that could be harmful for internally connected circuits on the grounding terminal. Fluctuations in soil properties may also lead to current crowding effect similar to those seen at the emitters of semiconductor transistors. In this work, soil samples are subjected to high impulse voltage discharge and the breakdown characteristics was profiled. The results from profiling discharge characteristics of soil in this work will contribute to the optimization of grounding protection system design in terms of electrode placement. This would also contribute to avoiding grounding electrode current crowding, ground potential rise fault and electromagnetic coupling faults.

  8. Considerations about the specific impulse of an antimatter-based thermal engine

    SciTech Connect

    Vulpetti, G.; Pecchioli, M. )

    1989-10-01

    Starting from both consolidated and new experimental data about the annihilation at rest of antiproton nucleons, and reconsidering the antimatter engine-design concepts that have been developed during the last 5-6 years, the practical limits of specific impulse are considered for classes of potential antimatter thrusters. The aim of this paper is to quantify considerations strongly related to the several different types of particles released by annihilation and the near-future technology. Major results from such an analysis are: (1) solid-shell gaseous-core engine specific impulses higher than 1000 s (the solid-core engine limit) may be attained only by appreciably decreasing the annihilation gamma-ray energy absorbed by the engine shells and, hence, by the propellant; and (2) specific impulses higher than about 6600 s cannot be achieved by a thermal engine because the annihilation charged-product engine energy efficiency to the gamma-ray engine energy-efficiency ratio is limited to about 40. Realistic value of this ratio is a maximum specific impluse of about 5800 s. 15 refs.

  9. Performance of different types of hearing protectors undergoing high-level impulse noise.

    PubMed

    Buck, Karl

    2009-01-01

    The paper describes the problems that may occur when hearing protectors, usually designed for industrial noise environments, are used for high-level impulse (weapon) noise. The military impulse noise environment is described, as are the different types of passive and active hearing protectors and the measurement procedures. The different mechanisms that may alter the effectiveness of the hearing protectors as well as their global efficiency when submitted to high-level impulse noise are presented. The paper also discusses how the performance values accessible to the user may be used in different damage risk criteria for continuous and impulse noise.

  10. Gender-specific mediational links between parenting styles, parental monitoring, impulsiveness, drinking control, and alcohol-related problems.

    PubMed

    Patock-Peckham, Julie A; King, Kevin M; Morgan-Lopez, Antonio A; Ulloa, Emilio C; Moses, Jennifer M Filson

    2011-03-01

    Recently, it has been suggested that traits may dynamically change as conditions change. One possible mechanism that may influence impulsiveness is parental monitoring. Parental monitoring reflects a knowledge regarding one's offspring's whereabouts and social connections. The aim of this investigation was to examine potential gender-specific parental influences to impulsiveness (general behavioral control), control over one's own drinking (specific behavioral control), and alcohol-related problems among individuals in a period of emerging adulthood. Direct and mediational links between parenting styles (permissive, authoritarian, and authoritative), parental monitoring, impulsiveness, drinking control, and alcohol-related problems were investigated. A multiple-group, SEM model with (316 women, 265 men) university students was examined. In general, the overall pattern among male and female respondents was distinct. For daughters, perceptions of a permissive father were indirectly linked to more alcohol-related problems through lower levels of monitoring by fathers and more impulsive symptoms. Perceptions of an authoritative father were also indirectly linked to fewer impulsive symptoms through higher levels of monitoring by fathers among daughters. For men, perceptions of a permissive mother were indirectly linked to more alcohol-related problems through lower levels of monitoring by mothers and more impulsive symptoms. For sons, perceptions of mother authoritativeness were indirectly linked to fewer alcohol-related problems through more monitoring by mothers and fewer impulsive symptoms. Monitoring by an opposite-gender parent mediated the link between parenting styles (i.e., permissive, authoritative) on impulsiveness.

  11. Reactive high power impulse magnetron sputtering: combining simulation and experiment

    NASA Astrophysics Data System (ADS)

    Kozak, Tomas; Vlcek, Jaroslav

    2016-09-01

    Reactive high-power impulse magnetron sputtering (HiPIMS) has recently been used for preparation of various oxide films with high application potential, such as TiO2, ZrO2, Ta2O5, HfO2, VO2. Using our patented method of pulsed reactive gas flow control with an optimized reactive gas inlet, we achieved significantly higher deposition rates compared to typical continuous dc magnetron depositions. We have developed a time-dependent model of the reactive HiPIMS. The model includes a depth-resolved description of the sputtered target (featuring sputtering, implantation and knock-on implantation processes) and a parametric description of the discharge plasma (dissociation of reactive gas, ionization and return of sputtered atoms and gas rarefaction). The model uses a combination of experimental and simulation data as input. We have calculated the composition of the target and substrate for several deposition conditions. The simulations predict a reduced compound coverage of the target in HiPIMS compared to the continuous dc sputtering regime which explains the increased deposition rate. The simulations show that an increased dissociation of oxygen in a HiPIMS discharge is beneficial to achieve stoichiometric films on the substrate at high deposition rates.

  12. Passive control of rotorcraft high-speed impulsive noise

    NASA Astrophysics Data System (ADS)

    Szulc, O.; Doerffer, P.; Tejero, F.

    2016-10-01

    A strong, normal shock wave, terminating a local supersonic area located at the tip of a helicopter blade, not only limits the aerodynamic performance, but also constitutes an origin of the High-Speed Impulsive (HSI) noise. The application of a passive control device (a shallow cavity covered by a perforated plate) just beneath the interaction region weakens the compression level, thus reducing the main source of the HSI noise. The numerical investigation based on the URANS approach and Bohning/Doerffer (BD) transpiration law (SPARC code) confirms a large potential of the new method. Two exemplary implementations, adapted to model helicopter rotors tested at NASA Ames facility in transonic conditions: Caradonna-Tung (lifting, transonic hover) and Caradonna-Laub-Tung (non-lifting, high-speed forward flight), demonstrate the possible gains in terms of the reduction of acoustic pressure fluctuations in the near-field of the blade tip. The CFD results are validated against the experimental data obtained for the reference configurations (no control), while the analysis of the passive control arrangement is based on a purely numerical research. The normal shock wave is effectively eliminated by the wall ventilation exerting a positive impact on the generated level of the HSI noise.

  13. Pharmacologic dissociation between impulsivity and alcohol drinking in High Alcohol Preferring mice

    PubMed Central

    Oberlin, Brandon G.; Bristow, R. Evan; Heighton, Meredith E.; Grahame, Nicholas J.

    2014-01-01

    Background Impulsivity is genetically correlated with, and precedes addictive behaviors and alcoholism. If impulsivity or attention is causally related to addiction, certain pharmacological manipulations of impulsivity and/or attention may affect alcohol drinking, and vice versa. The current studies were designed to explore the relationship among impulsivity, drinking, and vigilance in selectively bred High Alcohol Preferring (HAP) mice, a line that has previously demonstrated both high impulsivity and high alcohol consumption. Amphetamine, naltrexone and memantine were tested in a delay discounting (DD) task for their effects on impulsivity and vigilance. The same drugs and doses were also assessed for effects on alcohol drinking in a two-bottle choice test. Methods HAP mice were subjected to a modified version of adjusting amount DD using 0.5 sec and 10 sec delays to detect decreases and increases, respectively, in impulsive responding. In 2 experiments, mice were given amphetamine (0.4, 0.8 or 1.2 mg/kg), naltrexone (3 and 10 mg/kg), and memantine (1 and 5 mg/kg) before DD testing. Another pair of studies used scheduled access, two-bottle choice drinking to assess effects of amphetamine (0.4, 1.2, or 3.0 mg/kg), naltrexone (3 and 10 mg/kg), and memantine (1 and 5 mg/kg) on alcohol consumption. Results Amphetamine dose-dependently reduced impulsivity and vigilance decrement in DD, but similar doses left alcohol drinking unaffected. Naltrexone and memantine decreased alcohol intake at doses that did not affect water drinking, but had no effects on impulsivity or vigilance decrement in the DD task. Conclusions Contrary to our hypothesis, none of the drugs tested here, while effective either on alcohol drinking or impulsivity, decreased both behaviors. These findings suggest that the genetic association between drinking and impulsivity observed in this population is mediated by mechanisms other than those targeted by the drugs tested in these studies. PMID:20491739

  14. Plasma potential mapping of high power impulse magnetron sputtering discharges

    SciTech Connect

    Rauch, Albert; Mendelsberg, Rueben J.; Sanders, Jason M.; Anders, Andre

    2011-12-20

    Pulsed emissive probe techniques have been used to determine the plasma potential distribution of high power impulse magnetron sputtering (HiPIMS) discharges. An unbalanced magnetron with a niobium target in argon was investigated for pulse length of 100 μs at a pulse repetition rate of 100 Hz, giving a peak current of 170 A. The probe data were taken with a time resolution of 20 ns and a spatial resolution of 1 mm. It is shown that the local plasma potential varies greatly in space and time. The lowest potential was found over the target’s racetrack, gradually reaching anode potential (ground) several centimeters away from the target. The magnetic pre-sheath exhibits a funnel-shaped plasma potential resulting in an electric field which accelerates ions toward the racetrack. In certain regions and times, the potential exhibits weak local maxima which allow for ion acceleration to the substrate. Knowledge of the local E and static B fields lets us derive the electrons’ E×B drift velocity, which is about 105 m/s and shows structures in space and time.

  15. Discharge Physics of High Power Impulse Magnetron Sputtering

    SciTech Connect

    Anders, Andre

    2010-10-13

    High power impulse magnetron sputtering (HIPIMS) is pulsed sputtering where the peak power exceeds the time-averaged power by typically two orders of magnitude. The peak power density, averaged over the target area, can reach or exceed 107 W/m2, leading to plasma conditions that make ionization of the sputtered atoms very likely. A brief review of HIPIMS operation is given in a tutorial manner, illustrated by some original data related to the self-sputtering of niobium in argon and krypton. Emphasis is put on the current-voltage-time relationships near the threshold of self-sputtering runaway. The great variety of current pulse shapes delivers clues on the very strong gas rarefaction, self-sputtering runaway conditions, and the stopping of runaway due to the evolution of atom ionization and ion return probabilities as the gas plasma is replaced by metal plasma. The discussions are completed by considering instabilities and the special case of ?gasless? self-sputtering.

  16. Plasma potential mapping of high power impulse magnetron sputtering discharges

    SciTech Connect

    Rauch, Albert; Mendelsberg, Rueben J.; Sanders, Jason M.; Anders, Andre

    2012-04-15

    Pulsed emissive probe techniques have been used to determine the plasma potential distribution of high power impulse magnetron sputtering (HiPIMS) discharges. An unbalanced magnetron with a niobium target in argon was investigated for a pulse length of 100 {mu}s at a pulse repetition rate of 100 Hz, giving a peak current of 170 A. The probe data were recorded with a time resolution of 20 ns and a spatial resolution of 1 mm. It is shown that the local plasma potential varies greatly in space and time. The lowest potential was found over the target's racetrack, gradually reaching anode potential (ground) several centimeters away from the target. The magnetic presheath exhibits a funnel-shaped plasma potential resulting in an electric field which accelerates ions toward the racetrack. In certain regions and times, the potential exhibits weak local maxima which allow for ion acceleration to the substrate. Knowledge of the local E and static B fields lets us derive the electrons'ExB drift velocity, which is about 10{sup 5} m/s and shows structures in space and time.

  17. Low attentive and high impulsive rats: A translational animal model of ADHD and disorders of attention and impulse control.

    PubMed

    Hayward, Andrew; Tomlinson, Anneka; Neill, Joanna C

    2016-02-01

    Many human conditions such as attention deficit hyperactivity disorder (ADHD), schizophrenia and drug abuse are characterised by deficits in attention and impulse control. Carefully validated animal models are required to enhance our understanding of the pathophysiology of these disorders, enabling development of improved pharmacotherapy. Recent models have attempted to recreate the psychopathology of these conditions using chemical lesions or genetic manipulations. In a diverse population, where the aetiology is not fully understood and is multifactorial, these methods are restricted in their ability to identify novel targets for drug discovery. Two tasks of visual attention and impulsive action typically used in rodents and based on the human continuous performance task (CPT) include, the well-established 5 choice serial reaction time task (5C-SRTT) and the more recently validated, 5 choice continuous performance task (5C-CPT) which provides enhanced translational value. We suggest that separating animals by behavioural performance into high and low attentive and impulsivity cohorts using established parameters in these tasks offers a model with enhanced translational value. In this review, methods to separate animals are compared and the results discussed to highlight advantages over more constrained models, in addition to potential future directions for enhanced validation. Advantages include reliability, flexibility and enhanced translation to clinical conditions, all important considerations in modelling ADHD, schizophrenia and drug abuse, conditions with multifactorial aetiology. Based on the existing evidence, we suggest that future studies should incorporate an element of behavioural separation when studying the constructs of visual attention and impulsive action of relevance to human disorders.

  18. Performance characteristics of quasi-steady MPD discharges. [spacecraft plasma propulsion thrust efficiency and specific impulse

    NASA Technical Reports Server (NTRS)

    Rudolph, L. K.; Jahn, R. G.; Clark, K. E.; Von Jaskowsky, W. F.

    1976-01-01

    The onset of voltage fluctuations in a multi-megawatt quasi-steady MPD accelerator, indicative of increased cathode ablation and a consequent degradation of performance, is found to be a function of cathode size. With longer cathodes, this onset shifts to substantially higher powers per unit mass flow and the plasma exhaust velocity can be increased to values previously thought inaccessible to accelerators of this class. Centerline velocities up to 30 km/sec have been measured in argon, which for the observed exhaust profiles translate into specific impulses up to 2400 sec and corresponding thrust efficiencies above 30%.

  19. Monte-Carlo particle dynamics in a variable specific impulse magnetoplasma rocket

    SciTech Connect

    Ilin, A.V.; Diaz, F.R.C.; Squire, J.P.

    1999-01-01

    The self-consistent mathematical model in a Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is examined. Of particular importance is the effect of a magnetic nozzle in enhancing the axial momentum of the exhaust. Also, different geometries and rocket symmetries are considered. The magnetic configuration is modeled with an adaptable mesh, which increases accuracy without compromising the speed of the simulation. The single particle trajectories are integrated with an adaptive time-scheme, which can quickly solve extensive Monte-Carlo simulations for systems of hundred thousands of particles in a reasonable time (1--2 hours) and without the need for a powerful supercomputer.

  20. Specific cognitive-neurophysiological processes predict impulsivity in the childhood attention-deficit/hyperactivity disorder combined subtype.

    PubMed

    Bluschke, A; Roessner, V; Beste, C

    2016-04-01

    Attention-deficit/hyperactivity disorder (ADHD) is one of the most prevalent neuropsychiatric disorders in childhood. Besides inattention and hyperactivity, impulsivity is the third core symptom leading to diverse and serious problems. However, the neuronal mechanisms underlying impulsivity in ADHD are still not fully understood. This is all the more the case when patients with the ADHD combined subtype (ADHD-C) are considered who are characterized by both symptoms of inattention and hyperactivity/impulsivity. Combining high-density electroencephalography (EEG) recordings with source localization analyses, we examined what information processing stages are dysfunctional in ADHD-C (n = 20) compared with controls (n = 18). Patients with ADHD-C made more impulsive errors in a Go/No-go task than healthy controls. Neurophysiologically, different subprocesses from perceptual gating to attentional selection, resource allocation and response selection processes are altered in this patient group. Perceptual gating, stimulus-driven attention selection and resource allocation processes were more pronounced in ADHD-C, are related to activation differences in parieto-occipital networks and suggest attentional filtering deficits. However, only response selection processes, associated with medial prefrontal networks, predicted impulsive errors in ADHD-C. Although the clinical picture of ADHD-C is complex and a multitude of processing steps are altered, only a subset of processes seems to directly modulate impulsive behaviour. The present findings improve the understanding of mechanisms underlying impulsivity in patients with ADHD-C and might help to refine treatment algorithms focusing on impulsivity.

  1. High Trait Impulsivity Predicts Food Addiction-Like Behavior in the Rat

    PubMed Central

    Velázquez-Sánchez, Clara; Ferragud, Antonio; Moore, Catherine F; Everitt, Barry J; Sabino, Valentina; Cottone, Pietro

    2014-01-01

    Impulsivity is a behavioral trait frequently seen not only in drug-addicted individuals but also in individuals who pathologically overeat. However, whether impulsivity predates the development of uncontrollable feeding is unknown. In this study, we hypothesized that a high impulsivity trait precedes and confers vulnerability for food addiction-like behavior. For this purpose, we trained ad libitum-fed male Wistar rats in a differential reinforcement of low rates of responding (DRL) task to select Low- and High-impulsive rats. Then, we allowed Low- and High-impulsive rats to self-administer a highly palatable diet (Palatable group) or a regular chow diet (Chow group) in 1-h daily sessions, under fixed ratio (FR) 1, FR3, FR5, and under a progressive ratio (PR) schedules of reinforcement. In addition, we tested the compulsiveness for food in Low- and High-impulsive rats by measuring the food eaten in the aversive, open compartment of a light/dark conflict test. Finally, we measured the expression of the transcription factor ΔFosB in the shell and the core of the nucleus accumbens, which is a marker for neuroadaptive changes following addictive drug exposure. The data we obtained demonstrate that impulsivity is a trait that predicts the development of food addiction-like behaviors, including: (i) excessive intake, (ii) heightened motivation for food, and (iii) compulsive-like eating, when rats are given access to highly palatable food. In addition, we show that the food addiction phenotype in high impulsive subjects is characterized by an increased expression of the transcription factor ΔFosB in the nucleus accumbens shell. These results reveal that impulsivity confers an increased propensity to develop uncontrollable overeating of palatable food. PMID:24776685

  2. High trait impulsivity predicts food addiction-like behavior in the rat.

    PubMed

    Velázquez-Sánchez, Clara; Ferragud, Antonio; Moore, Catherine F; Everitt, Barry J; Sabino, Valentina; Cottone, Pietro

    2014-09-01

    Impulsivity is a behavioral trait frequently seen not only in drug-addicted individuals but also in individuals who pathologically overeat. However, whether impulsivity predates the development of uncontrollable feeding is unknown. In this study, we hypothesized that a high impulsivity trait precedes and confers vulnerability for food addiction-like behavior. For this purpose, we trained ad libitum-fed male Wistar rats in a differential reinforcement of low rates of responding (DRL) task to select Low- and High-impulsive rats. Then, we allowed Low- and High-impulsive rats to self-administer a highly palatable diet (Palatable group) or a regular chow diet (Chow group) in 1-h daily sessions, under fixed ratio (FR) 1, FR3, FR5, and under a progressive ratio (PR) schedules of reinforcement. In addition, we tested the compulsiveness for food in Low- and High-impulsive rats by measuring the food eaten in the aversive, open compartment of a light/dark conflict test. Finally, we measured the expression of the transcription factor ΔFosB in the shell and the core of the nucleus accumbens, which is a marker for neuroadaptive changes following addictive drug exposure. The data we obtained demonstrate that impulsivity is a trait that predicts the development of food addiction-like behaviors, including: (i) excessive intake, (ii) heightened motivation for food, and (iii) compulsive-like eating, when rats are given access to highly palatable food. In addition, we show that the food addiction phenotype in high impulsive subjects is characterized by an increased expression of the transcription factor ΔFosB in the nucleus accumbens shell. These results reveal that impulsivity confers an increased propensity to develop uncontrollable overeating of palatable food.

  3. Statistical studies of impulsive events at high latitudes

    NASA Technical Reports Server (NTRS)

    Lin, Z. M.; Bering, E. A.; Benbrook, J. R.; Liao, B.; Lanzerotti, L. J.; Maclennan, C. G.; Wolfe, A. N.; Friis-Christensen, E.

    1995-01-01

    A statistical study has been made of the high-latitude impulsive events that were observed during the 1985-1986 South Pole Balloon Campaign. The events were selected by searching for unipolar pulses greater than or equal to 10 nT above background in the vertical component of the magnetic field on the ground and/or pedestal or 'W' shaped horizontal electric field perturbations greater than or equal to 10 mV/m in amplitude and accompanied by perturbations in the vertical electric field at balloon altitude. A main event list comprising 112 events was compiled from the 468 hours of data available. Three aspects of the events were examined: the solar wind conditions prior to the event, local time of observation, and intrinsic properties of the events. The local time distribution was obtained from the 112 entry main event list and was found to be nearly uniform across the dayside, with no midday gap. The event rate found using our low-amplitude selection criteria was 0.7 event/hr, comparable to expectations based on in situ studies of the magnetopause. A total of 42 events were found for which data were available from Interplanetary Monitoring Platform (IMP) 8. Of these events, 12 occurred when the Z(sub GSM) component (B(sub Z)) of the interplanetary magnetic field (IMF) was northward and 30 occurred when B(sub Z) was southward or fluctuating. Only three of the B(sub Z) northward cases and only five of the B(sub Z) southward cases were preceded by pressure pulses greater than 0.4 nPa in amplitude. Ten of the events were studied in detail by means of a model-fitting method discussed elsewhere. This method infers values of several parameters, including the total current flowing in a coaxial or monopole system and a two-dimensional dipole system. The intrinsic properties of the events showed that only approximately 10% of the total current contributed to momentum transfer to the high-latitude ionosphere, that the direction of the motion depended more on local time of

  4. High Level Impulse Sounds and Human Hearing: Standards, Physiology, Quantification

    DTIC Science & Technology

    2012-05-01

    1976; Dancer , 2004). 3.1.2.2 Warned and Unwarned Response of the Ear The role of the AR in protecting hearing against impulse sounds has been...1974; Dancer , 2004). Price (2007a) refers to human reaction to unexpected and expected sounds as the unwarned response and warned response. The...Henderson et al., 2001; Maison and Liberman, 2000). This system has been referred to by Dancer (2004) as the inner ear acoustic reflex. Although

  5. Lateral prefrontal model-based signatures are reduced in healthy individuals with high trait impulsivity.

    PubMed

    Deserno, L; Wilbertz, T; Reiter, A; Horstmann, A; Neumann, J; Villringer, A; Heinze, H-J; Schlagenhauf, F

    2015-10-13

    High impulsivity is an important risk factor for addiction with evidence from endophenotype studies. In addiction, behavioral control is shifted toward the habitual end. Habitual control can be described by retrospective updating of reward expectations in 'model-free' temporal-difference algorithms. Goal-directed control relies on the prospective consideration of actions and their outcomes, which can be captured by forward-planning 'model-based' algorithms. So far, no studies have examined behavioral and neural signatures of model-free and model-based control in healthy high-impulsive individuals. Fifty healthy participants were drawn from the upper and lower ends of 452 individuals, completing the Barratt Impulsiveness Scale. All participants performed a sequential decision-making task during functional magnetic resonance imaging (fMRI) and underwent structural MRI. Behavioral and fMRI data were analyzed by means of computational algorithms reflecting model-free and model-based control. Both groups did not differ regarding the balance of model-free and model-based control, but high-impulsive individuals showed a subtle but significant accentuation of model-free control alone. Right lateral prefrontal model-based signatures were reduced in high-impulsive individuals. Effects of smoking, drinking, general cognition or gray matter density did not account for the findings. Irrespectively of impulsivity, gray matter density in the left dorsolateral prefrontal cortex was positively associated with model-based control. The present study supports the idea that high levels of impulsivity are accompanied by behavioral and neural signatures in favor of model-free behavioral control. Behavioral results in healthy high-impulsive individuals were qualitatively different to findings in patients with the same task. The predictive relevance of these results remains an important target for future longitudinal studies.

  6. Investigation of an Evaluation Method on the Improvement of Thrust and Specific Impulse by Nozzle Heating

    NASA Astrophysics Data System (ADS)

    Naganuma, Tetsushi; Iwaki, Yuuki; Sato, Shunya; Totani, Tsuyoshi; Wakita, Masashi; Nagata, Harunori

    A numerical analysis program is created to research effect of heat transfer for propellant flow in Laval nozzle and estimate improvements of thrust and specific impulse. Several types of gases are assumed as propellant. The energy ratio is defined as ratio of energy supplied to propellant by convective heat transfer to enthalpy of propellant at the inlet of nozzle. The energy ratio increases with elongating length of divergent nozzle, and finally becomes maximum value that depends on Prandtl number, propellant temperature and wall temperature at the inlet of nozzle. The conversion efficiency is defined as ratio of energy conversion to kinetic energy with nozzle to energy supplied to propellant. The conversion efficiency increases with elongating of divergent nozzle, and depends on profile of supplied heat.

  7. Single stage to orbit mass budgets derived from propellant density and specific impulse

    SciTech Connect

    Whitehead, J.C.

    1996-06-06

    The trade between specific impulse (Isp) and density is examined in view of Single Stage To Orbit (SSTO) requirements. Mass allocations for vehicle hardware are derived from these two properties, for several propellant combinations and a dual-fuel case. This comparative analysis, based on flight-proven hardware, indicates that the higher density of several alternative propellants compensates for reduced Isp, when compared with cryogenic oxygen and hydrogen. Approximately half the orbiting mass of a rocket- propelled SSTO vehicle must be allocated to propulsion hardware and residuals. Using hydrogen as the only fuel requires a slightly greater fraction of orbiting mass for propulsion, because hydrogen engines and tanks are heavier than those for denser fuels. The advantage of burning both a dense fuel and hydrogen in succession depends strongly on tripropellant engine weight. The implications of the calculations for SSTO vehicle design are discussed, especially with regard to the necessity to minimize non-tankage structure.

  8. Different relations between schedule-induced polydipsia and impulsive behaviour in the Spontaneously Hypertensive Rat and in high impulsive Wistar rats: questioning the role of impulsivity in adjunctive behaviour.

    PubMed

    Ibias, Javier; Pellón, Ricardo

    2014-09-01

    Rats belonging to three different strains (15 Wistar, 8 Spontaneously Hypertensive - SHR- and 8 Wistar Kyoto - WKY-) were used to evaluate the possible relationship between different levels of impulsivity and development of schedule-induced polydipsia (SIP). We first measured the rats' levels of impulsivity by means of delay-discounting and indifference-point procedures. Secondly, development of SIP was studied under a series of fixed time 15, 30, 60 and 120s food schedules, which were counterbalanced by means of a Latin-square design. Finally, we re-assessed the rats' levels of impulsivity by replicating the delay-discounting test. The findings showed that, starting from equivalent levels of impulsivity, development of SIP differed among the groups of rats. In comparison with the rest of the animals, the SHRs were observed to attain elevated drinking rates under SIP. On the other hand, the Wistar rats which had initial high impulsivity levels similar to those of the SHRs, displayed the lowest rates of induced drinking. Moreover, low levels of impulsivity in Wistar rats prior to SIP acquisition were reflected into high drinking rates. Relation of SIP and impulsivity is questioned by present results, which gives ground to the understanding of the behavioural mechanisms involved in adjunctive behaviour and its usefulness as an animal model of excessive behaviour.

  9. Mouthguard BITES (behavior, impulsivity, theory evaluation study): what drives mouthguard use among high school basketball and baseball/softball athletes.

    PubMed

    Collins, Christy L; McKenzie, Lara B; Roberts, Kristin J; Fields, Sarah K; Comstock, R Dawn

    2015-10-01

    Although mouthguards are effective, inexpensive, easy to use, and readily available, this form of protective equipment has been underutilized. "Impulsive delay discounting" (an index of impulsive behavior) among high school athletes may help explain their decision making regarding use of protective equipment such as mouthguards. We investigated the relationship between high school baseball, softball, and basketball players' mouthguard use, impulsive delay discounting, and the precaution adoption process model (a behavior change theory). A convenience sample of boys' and girls' basketball and baseball/softball players at 21 high schools in the Greater Columbus, Ohio, metro area completed a self-administered survey that captured their demographic information, knowledge, attitudes, and beliefs regarding mouthguard use, impulsive delay discounting, and precaution adoption process model stage. We surveyed a total of 1636 students (55.9 % male, 43.8 % female, 0.3 % unknown). Only 12.3 % reported using a mouthguard either every time or sometimes during practice or competition. The primary reasons reported for not wearing mouthguards were they were not required to (65.3 %) and that the athletes could not breathe or talk while wearing one (61.5 %). These reasons were consistent across sex and sport. Most athletes reported that their coaches (87.3 %) and parents (64.5 %) had never talked to them about wearing a mouthguard. Lower precaution adoption process model stage was significantly associated with higher impulsivity (p < 0.001) and higher delayed discounting (p = 0.016) after adjusting for school, sport, and sex. Voluntary mouthguard use among high school athletes playing basketball and baseball/softball remains low despite the risk of dental injury in these sports. Effective, evidence-based, targeted, and tailored interventions to improve adolescent athletes' use of mouthguards to prevent sports-related dental injuries should be based on the specific

  10. Impulsivity Characterization in the Roman High- and Low-Avoidance Rat Strains: Behavioral and Neurochemical Differences

    PubMed Central

    Moreno, Margarita; Cardona, Diana; Gómez, Maria José; Sánchez-Santed, Fernando; Tobeña, Adolf; Fernández-Teruel, Alberto; Campa, Leticia; Suñol, Cristina; Escarabajal, Maria Dolores; Torres, Carmen; Flores, Pilar

    2010-01-01

    The selective breeding of Roman high- (RHA) and low-avoidance (RLA) rats for rapid vs extremely poor acquisition of active avoidance behavior in a shuttle-box has generated two phenotypes with different emotional and motivational profiles. The phenotypic traits of the Roman rat lines/strains (outbred or inbred, respectively) include differences in sensation/novelty seeking, anxiety/fearfulness, stress responsivity, and susceptibility to addictive substances. We designed this study to characterize differences between the inbred RHA-I and RLA-I strains in the impulsivity trait by evaluating different aspects of the multifaceted nature of impulsive behaviors using two different models of impulsivity, the delay-discounting task and five-choice serial reaction time (5-CSRT) task. Previously, rats were evaluated on a schedule-induced polydipsia (SIP) task that has been suggested as a model of obsessive-compulsive disorder. RHA-I rats showed an increased acquisition of the SIP task, higher choice impulsivity in the delay-discounting task, and poor inhibitory control as shown by increased premature responses in the 5-CSRT task. Therefore, RHA-I rats manifested an increased impulsivity phenotype compared with RLA-I rats. Moreover, these differences in impulsivity were associated with basal neurochemical differences in striatum and nucleus accumbens monoamines found between the two strains. These findings characterize the Roman rat strains as a valid model for studying the different aspects of impulsive behavior and for analyzing the mechanisms involved in individual predisposition to impulsivity and its related psychopathologies. PMID:20090672

  11. General and Food-Specific Inhibitory Control As Moderators of the Effects of the Impulsive Systems on Food Choices.

    PubMed

    Zhang, Xuemeng; Chen, Shuaiyu; Chen, Hong; Gu, Yan; Xu, Wenjian

    2017-01-01

    The present study aimed to extend the application of the reflective-impulsive model to restrained eating and explore the effect of automatic attention (impulsive system) on food choices. Furthermore, we examined the moderating effects of general inhibitory control (G-IC) and food-specific inhibitory control (F-IC) on successful and unsuccessful restrained eaters (US-REs). Automatic attention was measured using "the EyeLink 1000," which tracked eye movements during the process of making food choices, and G-IC and F-IC were measured using the Stop-Signal Task. The results showed that food choices were related to automatic attention and that G-IC and F-IC moderated the predictive relationship between automatic attention and food choices. Furthermore, among successful restrained eaters (S-REs), automatic attention to high caloric foods did not predict food choices, regardless of whether G-IC or F-IC was high or low. Whereas food choice was positively correlated with automatic attention among US-REs with poor F-IC, this pattern was not observed in those with poor G-IC. In conclusion, the S-REs had more effective self-management skills and their food choices were affected less by automatic attention and inhibitory control. Unsuccessful restrained eating was associated with poor F-IC (not G-IC) and greater automatic attention to high caloric foods. Thus, clinical interventions should focus on enhancing F-IC, not G-IC, and on reducing automatic attention to high caloric foods.

  12. Maximization of the effective impulse delivered by a high-frequency/low-frequency planetary drill tool.

    PubMed

    Harkness, Patrick; Lucas, Margaret; Cardoni, Andrea

    2011-11-01

    Ultrasonic tools are used for a variety of cutting applications in surgery and the food industry, but when they are applied to harder materials, such as rock, their cutting performance declines because of the low effective impulse delivered by each vibration cycle. To overcome this problem, a technique known as high-frequency/low-frequency (or alternatively, ultrasonic/sonic) drilling is employed. In this approach, an ultrasonic step-horn is used to deliver an impulse to a free mass which subsequently moves toward a drilling bit, delivering the impulse on contact. The free mass then rebounds to complete the cycle. The horn has time between impacts to build significant vibration amplitude and thus delivers a much larger impulse to the free mass than could be delivered if it were applied directly to the target. To maximize the impulse delivered to the target by the cutting bit, both the momentum transfer from the ultrasonic horn to the free mass and the dynamics of the horn/free mass/cutting bit stack must be optimized. This paper uses finite element techniques to optimize the ultrasonic horns and numerical propagation of the stack dynamics to maximize the delivered effective impulse, validated in both cases by extensive experimental analysis.

  13. A review comparing cathodic arcs and high power impulse magnetron sputtering (HiPIMS)

    DOE PAGES

    Anders, André

    2014-09-02

    In this study, high power impulse magnetron sputtering (HiPIMS) has been in the center of attention over the last years as it is an emerging physical vapor deposition (PVD) technology that combines advantages of magnetron sputtering with various forms of energetic deposition of films such as ion plating and cathodic arc plasma deposition. It should not come at a surprise that many extension and variations of HiPIMS make use, intentionally or unintentionally, of previously discovered approaches to film processing such as substrate surface preparation by metal ion sputtering and phased biasing for film texture and stress control. Therefore, in thismore » review, an overview is given on some historical developments and features of cathodic arc and HiPIMS plasmas, showing commonalities and differences. To limit the scope, emphasis is put on plasma properties, as opposed to surveying the vast literature on specific film materials and their properties.« less

  14. A review comparing cathodic arcs and high power impulse magnetron sputtering (HiPIMS)

    SciTech Connect

    Anders, André

    2014-09-02

    In this study, high power impulse magnetron sputtering (HiPIMS) has been in the center of attention over the last years as it is an emerging physical vapor deposition (PVD) technology that combines advantages of magnetron sputtering with various forms of energetic deposition of films such as ion plating and cathodic arc plasma deposition. It should not come at a surprise that many extension and variations of HiPIMS make use, intentionally or unintentionally, of previously discovered approaches to film processing such as substrate surface preparation by metal ion sputtering and phased biasing for film texture and stress control. Therefore, in this review, an overview is given on some historical developments and features of cathodic arc and HiPIMS plasmas, showing commonalities and differences. To limit the scope, emphasis is put on plasma properties, as opposed to surveying the vast literature on specific film materials and their properties.

  15. Sex-specific attenuation of impulsive action by progesterone in a go/no-go task for cocaine in rats.

    PubMed

    Swalve, Natashia; Smethells, John R; Younk, Rebecca; Mitchell, Jared; Dougen, Ben; Carroll, Marilyn E

    2017-10-10

    Previous work indicated that progesterone (PRO) reduced impulsive choice for cocaine in female but not male rats (Smethells et al. Psychopharmacology 233:2999-3008, 2016). Impulsive action, typically measured by responding for a reinforcer during a signaled period of nonavailability of natural reinforcers, predicts initiation and escalation of drug use in animals and humans. The present study examined impulsive action for cocaine using PRO in male and female rats trained on a go/no-go task. Rats were trained on a go/no-go task to respond for cocaine infusions (0.4 mg/kg/inf). During the "go" component, responding was reinforced on a VI 30-s schedule, whereas during the "no-go" component, withholding a response was reinforced on a differential reinforcement of other behavior (DRO) 30-s schedule. A response during the no-go component resets the DRO timer and served as a measure of impulsive action. After baseline responding was established, rats were pretreated with vehicle (VEH) or PRO (0.5 mg/kg), and DRO resets and responding during the go component for cocaine were compared in males vs. females. DRO resets were significantly lower following PRO treatment compared to VEH in female, but not male, rats. Response rates and overall infusions during the go component were not significantly altered by PRO in either females or males. Treatment with PRO resulted in a sex-specific reduction in impulsive action for cocaine, while not affecting cocaine self-administration.

  16. Silicon oxynitride films deposited by reactive high power impulse magnetron sputtering using nitrous oxide as a single-source precursor

    SciTech Connect

    Hänninen, Tuomas Schmidt, Susann; Jensen, Jens; Hultman, Lars; Högberg, Hans

    2015-09-15

    Silicon oxynitride thin films were synthesized by reactive high power impulse magnetron sputtering of silicon in argon/nitrous oxide plasmas. Nitrous oxide was employed as a single-source precursor supplying oxygen and nitrogen for the film growth. The films were characterized by elastic recoil detection analysis, x-ray photoelectron spectroscopy, x-ray diffraction, x-ray reflectivity, scanning electron microscopy, and spectroscopic ellipsometry. Results show that the films are silicon rich, amorphous, and exhibit a random chemical bonding structure. The optical properties with the refractive index and the extinction coefficient correlate with the film elemental composition, showing decreasing values with increasing film oxygen and nitrogen content. The total percentage of oxygen and nitrogen in the films is controlled by adjusting the gas flow ratio in the deposition processes. Furthermore, it is shown that the film oxygen-to-nitrogen ratio can be tailored by the high power impulse magnetron sputtering-specific parameters pulse frequency and energy per pulse.

  17. Reduction of high-speed impulsive noise by blade planform modification of a model helicopter rotor

    NASA Technical Reports Server (NTRS)

    Conner, D. A.; Hoad, D. R.

    1982-01-01

    The reduction of high speed impulsive noise for the UH-1H helicopter was investigated by using an advanced main rotor system. The advanced rotor system had a tapered blade planform compared with the rectangular planform of the standard rotor system. Models of both the advanced main rotor system and the UH-1H standard main rotor system were tested at 1/4 scale in the 4 by 7 Meter Tunnel. In plane acoustic measurements of the high speed impulsive noise demonstrated that the advanced rotor system on the UH-1H helicopter reduced the high speed impulsive noise by up to 20 dB, with a reduction in overall sound pressure level of up to 5 dB.

  18. Impulsive movements lead to high hops on sand

    NASA Astrophysics Data System (ADS)

    Aguilar, Jeffrey; Goldman, Daniel I.

    2014-03-01

    Various animals exhibit locomotive behaviors (like sprinting and hopping) involving transient bursts of actuation coupled to the ground through internal elastic elements. The performance of such maneuvers is subject to reaction forces on the feet from the environment. On substrates like dry granular media, the laws that govern these forces are not fully understood, and can vary with foot size and shape, material compaction (measured by the volume fraction ϕ) and intrusion kinematics. To gain insight into how such interactions affect jumps on granular media, we study the performance of an actuated spring mass robot. We compare performance between two jump strategies: a single-cycle sine-wave actuation (a ``single jump'') and this actuation preceded by an impulsive preload (a ``preload jump''). We vary ϕ for both strategies, and find that ϕ significantly affects performance: we observe a 200% increase in the single jump height with only a 5% increase in volume fraction using a 7.62 cm diameter flat foot. The preload jump outperforms the single jump height by 150% for all ϕ. We hypothesize that this increase in performance results from higher intrusion velocities and accelerations associated with the preload. NSF POLS CAREER, Burroughs Wellcome Fund, and ARO.

  19. Deriving a dosage-response relationship for community response to high-energy impulsive noise

    NASA Technical Reports Server (NTRS)

    Fidell, Sanford; Pearsons, Karl S.

    1994-01-01

    The inability to systematically predict community response to exposure to sonic booms (and other high energy impulsive sounds) is a major impediment to credible analyses of the environmental effects of supersonic flight operations. Efforts to assess community response to high energy impulsive sounds are limited in at least two important ways. First, a paucity of appropriate empirical data makes it difficult to infer a dosage-response relationship by means similar to those used in the case of general transportation noise. Second, it is unclear how well the 'equal energy hypothesis' (the notion that duration, number, and level of individual events are directly interchangeable determinants of annoyance) applies to some forms of impulsive noise exposure. Some of the issues currently under consideration by a CHABA working group addressing these problems are discussed. These include means for applying information gained in controlled exposure studies about different rates of growth of annoyance with impulsive and non-impulsive sound exposure levels, and strategies for developing a dosage-response relationship in a data-poor area.

  20. Multidimensionality in Impulsivity and Alcohol Use: A Meta-Analysis using the UPPS Model of Impulsivity

    PubMed Central

    Coskunpinar, Ayca; Dir, Allyson L.; Cyders, Melissa A.

    2013-01-01

    Background Although there is considerable support for the relationship between impulsivity and alcohol use, the use of multidimensional conceptualizations of impulsivity and alcohol use has lead to varying relationship sizes across studies. The aims of the current meta-analysis are to (1) examine variability in the magnitude of the bivariate relationship between impulsivity and alcohol use across studies, and (2) describe the pattern of effects between specific impulsivity traits and alcohol use variables, using the UPPS Model of Impulsivity. Methods Ninety-six studies were meta-analyzed using a random effects model to examine the relationship between general impulsivity and alcohol use, as well as the relationships among separate impulsivity traits based in the UPPS model of impulsivity and specific alcohol use outcomes. Results Results indicate that, in general, impulsivity and alcohol use are related (r = .28); however, this effect size varied significantly across studies (from −.05 to 1.02). Drinking quantity was most strongly predicted by lack of perseverance (r = .32), whereas all traits equally predicted drinking frequency. Drinking problems were most highly related to negative (r = .35) and positive (r = .34) urgency, and alcohol dependence was most highly related to negative urgency (r = .38) and lack of planning (r = .37). Conclusion Effect sizes between impulsivity and alcohol use vary significantly by UPPS trait used in each study; thus, findings suggest and further reinforce the view in the literature that specific impulsivity-related constructs differentially relate to specific alcohol use outcomes. PMID:23578176

  1. Do individuals higher in impulsivity drink more impulsively? A pilot study within a high risk sample of young adults.

    PubMed

    Stevens, Angela K; Littlefield, Andrew K; Talley, Amelia E; Brown, Jennifer L

    2017-02-01

    Extant literature has established a strong relation between individual differences in "impulsivity" and alcohol consumption. However, the relation between "impulsivity," intentions-to-drink, and alcohol consumption has remained understudied. As a part of a larger study, 77 participants (60.5% female, 76.3% White, M age=20.8) completed 10days of daily diary reports regarding their intention to use alcohol and alcohol consumption. Hierarchical linear modeling (HLM) was used to estimate within-person relations between intentions-to-drink and subsequent alcohol use. All models were adjusted for participant age, biological sex, and day of the week. Results showed a strong positive association between daily intention to consume alcohol and self-reported alcohol use (β=0.50, p<0.01). Importantly, tests of interactions indicated that individuals higher in impulsivity were not significantly more likely to engage in unplanned drinking. Multilevel mediation analyses indicated significant indirect effects between impulsivity-like constructs, including positive urgency, lack-of-planning, and self-report delay discounting, and reported daily alcohol consumption via higher overall (i.e., between-person) levels of intentions-to-drink; that is, individuals who reported higher levels of these impulsivity-related constructs were more likely to intend to drink across the 10-days and, in turn, consumed more alcohol. Findings from the study suggest that treatment providers could address drinking intentions among individuals higher in impulsivity and work to establish potential replacement behaviors to reduce alcohol consumption in this population.

  2. Model rotor high-speed impulsive noise - Parametric variations and full-scale comparisons

    NASA Astrophysics Data System (ADS)

    Splettstoesser, W. R.; Schultz, K. J.; Schmitz, F. H.; Boxwell, D. A.

    1983-05-01

    The results of a 1/7-scale model of the AH-1 series helicopter main rotor test in the German-Dutch anechoic wind tunnel are discussed, with emphasis given on exploring the important scaling parameters of helicopter-rotor high-speed impulsive noise. Nondimensional parameters are derived from the governing equations and employed to compare the model rotor measurements with full-scale investigations, using an equivalent in-flight technique. The peak acoustic pressure, impulsive noise directivity, and acoustic waveform of the model are found to scale well in shape and in amplitude with full-scale results. Parametric variations of the model-rotor acoustic measurements, such as the change of the high-speed impulsive noise level over a range of advancing-tip Mach numbers at constant advance ratio or constant velocity, are presented. It is concluded that model-scale rotors can be used to explore potential acoustic design innovations on full-scale helicopters.

  3. Cocaine-, caffeine-, and stress-evoked cocaine reinstatement in high vs. low impulsive rats: Treatment with allopregnanolone

    PubMed Central

    Regier, Paul S.; Claxton, Alexander B.; Zlebnik, Natalie E.; Carroll, Marilyn E.

    2014-01-01

    Background Previous research indicates that individual differences in traits such as impulsivity, avidity for sweets, and novelty reactivity are predictors of several aspects of drug addiction. Specifically, rats that rank high on these behavioral measures are more likely than their low drug-seeking counterparts to exhibit several characteristics of drug-seeking behavior. In contrast, initial work suggests that the low drug-seeking animals are more reactive to negative events (e.g., punishment and anxiogenic stimuli). The goal of this study was to compare high and low impulsive rats on reinstatement of cocaine-seeking behavior elicited by cocaine (COC) and by negative stimuli such as the stress-inducing agent yohimbine (YOH) or a high dose of caffeine (CAFF). An additional goal was to determine whether treatment with allopregnanolone (ALLO) would reduce reinstatement (or relapse) of cocaine-seeking behavior under these priming conditions. Methods Female rats were selected as high (HiI) or low (LoI) impulsive using a delay-discounting task. After selection, they were allowed to self-administer cocaine for 12 days. Cocaine was then replaced with saline, and rats extinguished lever responding over 16 days. Subsequently, rats were pretreated with either vehicle control or ALLO, and cocaine seeking was reinstated by injections of COC, CAFF, or YOH. Results While there were no phenotype differences in maintenance and extinction of cocaine self-administration or reinstatement under control treatment conditions, ALLO attenuated COC- and CAFF-primed reinstatement in LoI but not HiI rats. Conclusions Overall, the present findings suggest that individual differences in impulsive behavior may influence efficacy of interventions aimed to reduce drug-seeking behavior. PMID:25073834

  4. Cocaine-, caffeine-, and stress-evoked cocaine reinstatement in high vs. low impulsive rats: treatment with allopregnanolone.

    PubMed

    Regier, Paul S; Claxton, Alexander B; Zlebnik, Natalie E; Carroll, Marilyn E

    2014-10-01

    Previous research indicates that individual differences in traits such as impulsivity, avidity for sweets, and novelty reactivity are predictors of several aspects of drug addiction. Specifically, rats that rank high on these behavioral measures are more likely than their low drug-seeking counterparts to exhibit several characteristics of drug-seeking behavior. In contrast, initial work suggests that the low drug-seeking animals are more reactive to negative events (e.g., punishment and anxiogenic stimuli). The goal of this study was to compare high and low impulsive rats on reinstatement of cocaine-seeking behavior elicited by cocaine (COC) and by negative stimuli such as the stress-inducing agent yohimbine (YOH) or a high dose of caffeine (CAFF). An additional goal was to determine whether treatment with allopregnanolone (ALLO) would reduce reinstatement (or relapse) of cocaine-seeking behavior under these priming conditions. Female rats were selected as high (HiI) or low (LoI) impulsive using a delay-discounting task. After selection, they were allowed to self-administer cocaine for 12 days. Cocaine was then replaced with saline, and rats extinguished lever responding over 16 days. Subsequently, rats were pretreated with either vehicle control or ALLO, and cocaine seeking was reinstated by injections of COC, CAFF, or YOH. While there were no phenotype differences in maintenance and extinction of cocaine self-administration or reinstatement under control treatment conditions, ALLO attenuated COC- and CAFF-primed reinstatement in LoI but not HiI rats. Overall, the present findings suggest that individual differences in impulsive behavior may influence efficacy of interventions aimed to reduce drug-seeking behavior. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  5. A web-based study of bipolarity and impulsivity in athletes engaging in extreme and high-risk sports.

    PubMed

    Dudek, Dominika; Siwek, Marcin; Jaeschke, Rafał; Drozdowicz, Katarzyna; Styczeń, Krzysztof; Arciszewska, Aleksandra; Chrobak, Adrian A; Rybakowski, Janusz K

    2016-06-01

    We hypothesised that men and women who engage in extreme or high-risk sports would score higher on standardised measures of bipolarity and impulsivity compared to age and gender matched controls. Four-hundred and eighty extreme or high-risk athletes (255 males and 225 females) and 235 age-matched control persons (107 males and 128 females) were enrolled into the web-based case-control study. The Mood Disorder Questionnaire (MDQ) and Barratt Impulsiveness Scale (BIS-11) were administered to screen for bipolarity and impulsive behaviours, respectively. Results indicated that extreme or high-risk athletes had significantly higher scores of bipolarity and impulsivity, and lower scores on cognitive complexity of the BIS-11, compared to controls. Further, there were positive correlations between the MDQ and BIS-11 scores. These results showed greater rates of bipolarity and impulsivity, in the extreme or high-risk athletes, suggesting these measures are sensitive to high-risk behaviours.

  6. Neural connectivity during reward expectation dissociates psychopathic criminals from non-criminal individuals with high impulsive/antisocial psychopathic traits.

    PubMed

    Geurts, Dirk E M; von Borries, Katinka; Volman, Inge; Bulten, Berend Hendrik; Cools, Roshan; Verkes, Robbert-Jan

    2016-08-01

    Criminal behaviour poses a big challenge for society. A thorough understanding of the neurobiological mechanisms underlying criminality could optimize its prevention and management. Specifically,elucidating the neural mechanisms underpinning reward expectation might be pivotal to understanding criminal behaviour. So far no study has assessed reward expectation and its mechanisms in a criminal sample. To fill this gap, we assessed reward expectation in incarcerated, psychopathic criminals. We compared this group to two groups of non-criminal individuals: one with high levels and another with low levels of impulsive/antisocial traits. Functional magnetic resonance imaging was used to quantify neural responses to reward expectancy. Psychophysiological interaction analyses were performed to examine differences in functional connectivity patterns of reward-related regions. The data suggest that overt criminality is characterized, not by abnormal reward expectation per se, but rather by enhanced communication between reward-related striatal regions and frontal brain regions. We establish that incarcerated psychopathic criminals can be dissociated from non-criminal individuals with comparable impulsive/antisocial personality tendencies based on the degree to which reward-related brain regions interact with brain regions that control behaviour. The present results help us understand why some people act according to their impulsive/antisocial personality while others are able to behave adaptively despite reward-related urges.

  7. Neural connectivity during reward expectation dissociates psychopathic criminals from non-criminal individuals with high impulsive/antisocial psychopathic traits

    PubMed Central

    von Borries, Katinka; Volman, Inge; Bulten, Berend Hendrik; Cools, Roshan; Verkes, Robbert-Jan

    2016-01-01

    Criminal behaviour poses a big challenge for society. A thorough understanding of the neurobiological mechanisms underlying criminality could optimize its prevention and management. Specifically,elucidating the neural mechanisms underpinning reward expectation might be pivotal to understanding criminal behaviour. So far no study has assessed reward expectation and its mechanisms in a criminal sample. To fill this gap, we assessed reward expectation in incarcerated, psychopathic criminals. We compared this group to two groups of non-criminal individuals: one with high levels and another with low levels of impulsive/antisocial traits. Functional magnetic resonance imaging was used to quantify neural responses to reward expectancy. Psychophysiological interaction analyses were performed to examine differences in functional connectivity patterns of reward-related regions. The data suggest that overt criminality is characterized, not by abnormal reward expectation per se, but rather by enhanced communication between reward-related striatal regions and frontal brain regions. We establish that incarcerated psychopathic criminals can be dissociated from non-criminal individuals with comparable impulsive/antisocial personality tendencies based on the degree to which reward-related brain regions interact with brain regions that control behaviour. The present results help us understand why some people act according to their impulsive/antisocial personality while others are able to behave adaptively despite reward-related urges. PMID:27217111

  8. Impulsive control for fast nanopositioning.

    PubMed

    Tuma, Tomas; Sebastian, Abu; Häberle, Walter; Lygeros, John; Pantazi, Angeliki

    2011-04-01

    In this paper we present a non-linear control scheme for high-speed nanopositioning based on impulsive control. Unlike in the case of a linear feedback controller, the controller states are altered in a discontinuous manner at specific instances in time. Using this technique, it is possible to simultaneously achieve good tracking performance, disturbance rejection and tolerance to measurement noise. Impulsive control is demonstrated experimentally on an atomic force microscope. A significant improvement in tracking performance is demonstrated.

  9. Modeling of the Reactive High Power Impulse Magnetron Sputtering (HiPIMS) process

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Jon Tomas; Lundin, Daniel; Raadu, Michael; Brenning, Nils; Minea, Tiberiu

    2015-09-01

    Reactive high power impulse magnetron sputtering (HiPIMS) provides both a high ionization fraction of the sputtered material and a high dissociation fraction of the molecular gas. We demonstrate this through an ionization region model (IRM) of the reactive Ar/O2 HiPIMS discharge with a titanium target. We explore the influence of oxygen dilution on the discharge properties such as electron density, the ionization fraction of the sputtered vapor and the oxygen dissociation fraction. We discuss the important processes and challenges for more detailed modeling of the reactive HiPIMS discharge. Furthermore, we discuss experimental observations during reactive high power impulse magnetron sputtering sputtering (HiPIMS) of Ti target in Ar/N2 and Ar/O2 atmosphere. The discharge current waveform is highly dependent on the reactive gas flow rate, pulse repetition frequency and discharge voltage. The discharge current increases with decreasing repetition frequency and increasing flowrate of the reactive gas.

  10. Child Problems as a Moderator of Relations Between Maternal Impulsivity and Family Environment in a High-Risk Sample.

    PubMed

    Friedman, Carly K; Ryan, Stacy R; Charles, Nora E; Mathias, Charles W; Acheson, Ashley; Dougherty, Donald M

    2016-08-23

    Previous studies have suggested that maternal characteristics are related to family environment; however, the relation between maternal impulsivity, in particular, and family environment is not well understood. As such, we examined direct relations between maternal impulsivity and family environment, as well as whether the relation between maternal impulsivity and family environment was moderated by child problems for sons and daughters. We hypothesized that child problems would moderate the association between maternal impulsivity and family environment. We also explored whether these associations differ for boys and girls. Data from the initial visit of a longitudinal study was used for the current study. Participants included 297 youth (137 boys; 160 girls) of 10 to 12 years of age (M = 10.99, SD = .84) and their mothers. The majority of the sample had a family history of substance use disorder (n = 236). Hierarchical linear regressions showed that for sons there was a significant interaction between maternal impulsivity and child problems on family environment. Maternal impulsivity was positively related to family environment problems among sons with few emotional and behavioral problems, but there was no significant correlation among sons with high problem levels. Among daughters, there was no significant interaction between maternal impulsivity and child emotional and behavioral problems on family environment. The results suggest that the association between maternal impulsivity and family environment may depend on problem level and child gender. Thus, addressing maternal impulsivity in therapy may benefit some families.

  11. Comparison of New Methods for Assessing Community Response to High Energy Impulsive Sounds

    NASA Technical Reports Server (NTRS)

    Fidell, Sanford; Pearsons, Karl S.

    1996-01-01

    The latest CHABA Working Group to have reviewed published information about the effects of high energy impulsive sounds (such as sonic booms) on communities has recommended abandonment of the dosage-response relationship identified by its predecessor in favor of two alternate prediction method. Both of the new assessment methods continue to rely on C-weighted measurements of impulsive sounds One of the two assessment methods retains the standard assumptions of the 'equal energy hypothesis' (the notion that annoyance is governed simply by the product of level, duration, and number noise events), and further assumes that the rate of growth of the prevalence of annoyance is proportional to the rate of growth of loudness with level. The other assessment method, however, assumes a level dependent (non-equal energy) summation of the C-weighted sound exposure levels of individual impulsive events. Since predictions of the second method are distribution-dependent, they are not readily represents graphically in the form of a single dosage-response function. The effects on annoyance predictions of variance in distributions of CSEL values of impulsive sounds are explored in this presentation.

  12. Comparison of New Methods for Assessing Community Response to High Energy Impulsive Sounds

    NASA Technical Reports Server (NTRS)

    Fidell, Sanford; Pearsons, Karl S.

    1996-01-01

    The latest CHABA Working Group to have reviewed published information about the effects of high energy impulsive sounds (such as sonic booms) on communities has recommended abandonment of the dosage-response relationship identified by its predecessor in favor of two alternate prediction method. Both of the new assessment methods continue to rely on C-weighted measurements of impulsive sounds One of the two assessment methods retains the standard assumptions of the 'equal energy hypothesis' (the notion that annoyance is governed simply by the product of level, duration, and number noise events), and further assumes that the rate of growth of the prevalence of annoyance is proportional to the rate of growth of loudness with level. The other assessment method, however, assumes a level dependent (non-equal energy) summation of the C-weighted sound exposure levels of individual impulsive events. Since predictions of the second method are distribution-dependent, they are not readily represents graphically in the form of a single dosage-response function. The effects on annoyance predictions of variance in distributions of CSEL values of impulsive sounds are explored in this presentation.

  13. Effects of smoking abstinence on impulsive behavior among smokers high and low in ADHD-like symptoms.

    PubMed

    Ashare, Rebecca L; Hawk, Larry W

    2012-01-01

    Impulsivity, a multifaceted construct that includes inhibitory control and heightened preference for immediate reward, is central to models of drug use and abuse. Within a self-medication framework, abstinence from smoking may lead to an increase in impulsive behavior and the likelihood of relapse, particularly among persons with disorders (e.g., attention-deficit/hyperactivity disorder, ADHD) and personality traits (e.g., impulsivity) linked to impulsive behavior. This study aimed to examine the effects of smoking abstinence on multiple measures of impulsivity among a non-clinical sample of adult smokers selected for high and low levels of ADHD symptoms. In a within-subjects design, participants selected for high or low levels of self-reported ADHD symptoms (N = 56) completed sessions following overnight abstinence and when smoking as usual (order counterbalanced). Measures of impulsive behavior included response inhibition (i.e., stop signal task), interference control (i.e., attentional modification of prepulse inhibition (PPI) of startle), and impulsive choice (i.e., hypothetical delay discounting). As hypothesized, abstinence decreased response inhibition and PPI. Although ADHD symptoms moderated abstinence effects on impulsive choice and response inhibition, the pattern was opposite to our predictions: the low-ADHD group responded more impulsively when abstinent, whereas the high-ADHD group was relatively unaffected by abstinence. These findings highlight the importance of utilizing multiple laboratory measures to examine a multifactorial construct such as impulsive behavior and raise questions about how best to assess symptoms of ADHD and impulsivity among non-abstinent smokers.

  14. JOLT: A Highly Directive, Very Intensive, Impulse-Like Radiator

    DTIC Science & Technology

    2006-05-01

    to suppress corona. In addition, multiple sheets of Mylar are installed to prevent surface flashover along the Sylgard 184 between the connections...Hz, a criterion to insure the inhibition of surface flashover in a high pressure atmosphere has been developed. The switch is composed of copper... surface flashover along the high pressure gas/insulating solid interface has been successfully demonstrated under pulse repetition rates of 600 Hz

  15. Evidence for Highly Inhomogeneous mm-Wave Sources During the Impulsive Flare of May 9, 1991

    NASA Technical Reports Server (NTRS)

    Hermann, R.; Magun, A.; Kaufmann, P.; Correia, E.; Costa, J. E. R.; Machado, M. E.; Fishman, G.

    1997-01-01

    In this paper multiwavelength observations of an impulsive flare of May 9, 1991 are presented. This event was observed with the 48 GHz multibeam focal array used at the Itapetinga radio telescope, the microwave patrol telescopes at Bem and the BATSE high time resolution hard X-ray spectrometer on board CGRO. While spatially unresolved low sensitivity observations show two major impulsive peaks, the mm-wave observations with the ability of spatially high resolved tracking of the emission centroids suggest a primarily bipolar source configuration. For the first time two mm-wave sources with a spacing below the HPBW could be separated with the multibeam technique. The general features of the observations are explained as emission of partially trapped electrons. Furthermore we present evidence for highly inhomogeneous substructures within one of the two mm-wave sources for which the positional scatter of the emission center, within 2s, is less than 2".

  16. Evidence for Highly Inhomogeneous mm-Wave Sources During the Impulsive Flare of May 9, 1991

    NASA Technical Reports Server (NTRS)

    Hermann, R.; Magun, A.; Kaufmann, P.; Correia, E.; Costa, J. E. R.; Machado, M. E.; Fishman, G.

    1997-01-01

    In this paper multiwavelength observations of an impulsive flare of May 9, 1991 are presented. This event was observed with the 48 GHz multibeam focal array used at the Itapetinga radio telescope, the microwave patrol telescopes at Bem and the BATSE high time resolution hard X-ray spectrometer on board CGRO. While spatially unresolved low sensitivity observations show two major impulsive peaks, the mm-wave observations with the ability of spatially high resolved tracking of the emission centroids suggest a primarily bipolar source configuration. For the first time two mm-wave sources with a spacing below the HPBW could be separated with the multibeam technique. The general features of the observations are explained as emission of partially trapped electrons. Furthermore we present evidence for highly inhomogeneous substructures within one of the two mm-wave sources for which the positional scatter of the emission center, within 2s, is less than 2".

  17. Characterization of high power impulse magnetron sputtering discharges

    NASA Astrophysics Data System (ADS)

    Hala, Matej

    Paper I: In the first paper, we present a new approach in the characterization of the high power pulsed magnetron sputtering (HiPIMS) discharge evolution—time- and species-resolved plasma imaging—employing a set of band-pass optical interference filters suitable for the isolation of the emission originating from different species populating the plasma. We demonstrate that the introduction of such filters can be used to distinguish different phases of the discharge, and to visualize numerous plasma effects including background gas excitations during the discharge ignition, gas shock waves, and expansion of metal-rich plasmas. In particular, the application of this technique is shown on the diagnostics of the 200 µs long non-reactive HiPIMS discharges using a Cr target. Paper II: In order to gain further information about the dynamics of reactive HiPIMS discharges, both fast plasma imaging and time- and space-resolved optical emission spectroscopy (OES) are used for a systematic investigation of the 200 µs long HiPIMS pulses operated in Ar, N2 and N 2/Ar mixtures and at various pressures. It is observed that the dense metal plasma created next to the target propagates in the reactor at a speed ranging from 0.7 to 3.5 km s-1, depending on the working gas composition and the pressure. In fact, it increases with higher N 2 concentration and with lower pressure. The visible form of the propagating plasma wave changes from a hemispherical shape in Ar to a drop-like shape extending far from the target with increasing N2 concentration, owing to the significant emission from molecular N2. Interestingly, the evidence of the target self-sputtering is found for all investigated conditions, including pure N2 atmosphere. Paper III: Here, we report on the time- and species-resolved plasma imaging analysis of the dynamics of the 200 µs long HiPIMS discharges above a Cr target ignited in pure O2. It is shown that the discharge emission is dominated solely by neutral and

  18. The Influence of Using Momentum and Impulse Computer Simulation to Senior High School Students’ Concept Mastery

    NASA Astrophysics Data System (ADS)

    Kaniawati, I.; Samsudin, A.; Hasopa, Y.; Sutrisno, A. D.; Suhendi, E.

    2016-08-01

    This research is based on students’ lack of mastery of physics abstract concepts. Thus, this study aims to improve senior high school students’ mastery of momentum and impulse concepts with the use of computer simulation. To achieve these objectives, the research method employed was pre experimental design with one group pre-test post-test. A total of 36 science students of grade 11 in one of public senior high school in Bandung became the sample in this study. The instruments utilized to determine the increase of students’ concept mastery were pretest and posttest in the form of multiple choices. After using computer simulations in physics learning, students’ mastery of momentum and impulse concept has increased as indicated by the normalized gain of 0.64 with the medium category.

  19. Adaptive iterated function systems filter for images highly corrupted with fixed - Value impulse noise

    NASA Astrophysics Data System (ADS)

    Shanmugavadivu, P.; Eliahim Jeevaraj, P. S.

    2014-06-01

    The Adaptive Iterated Functions Systems (AIFS) Filter presented in this paper has an outstanding potential to attenuate the fixed-value impulse noise in images. This filter has two distinct phases namely noise detection and noise correction which uses Measure of Statistics and Iterated Function Systems (IFS) respectively. The performance of AIFS filter is assessed by three metrics namely, Peak Signal-to-Noise Ratio (PSNR), Mean Structural Similarity Index Matrix (MSSIM) and Human Visual Perception (HVP). The quantitative measures PSNR and MSSIM endorse the merit of this filter in terms of degree of noise suppression and details/edge preservation respectively, in comparison with the high performing filters reported in the recent literature. The qualitative measure HVP confirms the noise suppression ability of the devised filter. This computationally simple noise filter broadly finds application wherein the images are highly degraded by fixed-value impulse noise.

  20. On the electron energy in the high power impulse magnetron sputtering discharge

    SciTech Connect

    Gudmundsson, J. T.; Sigurjonsson, P.; Larsson, P.; Lundin, D.; Helmersson, U.

    2009-06-15

    The temporal variation of the electron energy distribution function (EEDF) was measured with a Langmuir probe in a high power impulse magnetron sputtering (HiPIMS) discharge at 3 and 20 mTorr pressures. In the HiPIMS discharge a high power pulse is applied to a planar magnetron giving a high electron density and highly ionized sputtered vapor. The measured EEDF is Maxwellian-like during the pulse; it is broader for lower discharge pressure and it becomes narrower as the pulse progresses. This indicates that the plasma cools as the pulse progresses, probably due to high metal content of the discharge.

  1. A high power impulse magnetron sputtering model to explain high deposition rate magnetic field configurations

    NASA Astrophysics Data System (ADS)

    Raman, Priya; Weberski, Justin; Cheng, Matthew; Shchelkanov, Ivan; Ruzic, David N.

    2016-10-01

    High Power Impulse Magnetron Sputtering (HiPIMS) is one of the recent developments in the field of magnetron sputtering technology that is capable of producing high performance, high quality thin films. Commercial implementation of HiPIMS technology has been a huge challenge due to its lower deposition rates compared to direct current Magnetron Sputtering. The cylindrically symmetric "TriPack" magnet pack for a 10 cm sputter magnetron that was developed at the Center for Plasma Material Interactions was able to produce higher deposition rates in HiPIMS compared to conventional pack HiPIMS for the same average power. The "TriPack" magnet pack in HiPIMS produces superior substrate uniformity without the need of substrate rotation in addition to producing higher metal ion fraction to the substrate when compared to the conventional pack HiPIMS [Raman et al., Surf. Coat. Technol. 293, 10 (2016)]. The films that are deposited using the "TriPack" magnet pack have much smaller grains compared to conventional pack DC and HiPIMS films. In this paper, the reasons behind the observed increase in HiPIMS deposition rates from the TriPack magnet pack along with a modified particle flux model is discussed.

  2. Diagnostic Ultrasound High Mechanical Index Impulses Restore Microvascular Flow in Peripheral Arterial Thromboembolism

    PubMed Central

    Porter, Thomas R.; Radio, Stanley; Lof, John; Everbach, Carr; Powers, Jeffry E.; Vignon, Francois; Shi, William T.; Xie, Feng

    2016-01-01

    We sought to explore mechanistically how intermittent high mechanical index (MI) diagnostic ultrasound impulses restore microvascular flow. Thrombotic microvascular obstruction was created in the rat hindlimb muscle of 36 rats. A diagnostic transducer confirmed occlusion with low MI imaging during an intravenous microbubble infusion. This same transducer was used to intermittently apply an MI that produced stable or inertial (IC) cavitation for 10 minutes through a tissue mimicking phantom. A nitric oxide (NO) inhibitor L-NAME was pre-administered in six rats. Plateau microvascular contrast intensity quantified skeletal microvascular blood volume (MBV), and post mortem staining examined for perivascular hemorrhage. Intermittent IC impulses produced the greatest recovery of MBV (p<0.0001; ANOVA). NO inhibition did not affect the skeletal MBV improvement, but did result in more perivascular hemorrhage. IC inducing pulses from a diagnostic transducer can reverse microvascular obstruction following acute arterial thromboembolism. NO may prevent unwanted bioeffects from these IC pulses. PMID:27083977

  3. Attenuation of front-end reflections in an impulse radar using high-speed switching

    NASA Astrophysics Data System (ADS)

    Mazzaro, Gregory J.; Ressler, Marc A.; Smith, Gregory D.

    2011-06-01

    Pulse reflection between front-end components is a common problem for impulse radar systems. Such reflections arise because radio frequency components are rarely impedance-matched over an ultra-wide bandwidth. Any mismatch between components causes a portion of the impulse to reflect within the radar front-end. If the reflection couples into the transmit antenna, the radar emits an unintended, delayed and distorted replica of the intended radar transmission. These undesired transmissions reflect from the radar environment, produce echoes in the radar image, and generate false alarms in the vicinity of actual targets. The proposed solution for eliminating these echoes, without redesigning the transmit antenna, is to dissipate pulse reflections in a matched load before they are emitted. A high-speed switch directs the desired pulse to the antenna and redirects the undesired reflection from the antenna to a matched load. The Synchronous Impulse Reconstruction (SIRE) radar developed by the Army Research Laboratory (ARL) is the case-study. This paper reviews the current front-end design, provides a recent radar image which displays the aforementioned echoes, and describes the switch-cable-load circuit solution for eliminating the echoes. The consequences of inserting each portion of the new hardware into the radar front-end are explained. Measurements on the front-end with the high-speed switch show an attenuation of the undesired pulse transmissions of more than 18 dB and an attenuation in the desired pulse transmission of less than 3 dB.

  4. Adaptive two-pass rank order filter to remove impulse noise in highly corrupted images.

    PubMed

    Xu, Xiaoyin; Miller, Eric L; Chen, Dongbin; Sarhadi, Mansoor

    2004-02-01

    In this paper, we present an adaptive two-pass rank order filter to remove impulse noise in highly corrupted images. When the noise ratio is high, rank order filters, such as the median filter for example, can produce unsatisfactory results. Better results can be obtained by applying the filter twice, which we call two-pass filtering. To further improve the performance, we develop an adaptive two-pass rank order filter. Between the passes of filtering, an adaptive process is used to detect irregularities in the spatial distribution of the estimated impulse noise. The adaptive process then selectively replaces some pixels changed by the first pass of filtering with their original observed pixel values. These pixels are then kept unchanged during the second filtering. In combination, the adaptive process and the second filter eliminate more impulse noise and restore some pixels that are mistakenly altered by the first filtering. As a final result, the reconstructed image maintains a higher degree of fidelity and has a smaller amount of noise. The idea of adaptive two-pass processing can be applied to many rank order filters, such as a center-weighted median filter (CWMF), adaptive CWMF, lower-upper-middle filter, and soft-decision rank-order-mean filter. Results from computer simulations are used to demonstrate the performance of this type of adaptation using a number of basic rank order filters.

  5. Ion energies in high power impulse magnetron sputtering with and without localized ionization zones

    SciTech Connect

    Yang, Yuchen; Tanaka, Koichi; Liu, Jason; Anders, André

    2015-03-23

    High speed imaging of high power impulse magnetron sputtering discharges has revealed that ionization is localized in moving ionization zones but localization disappears at high currents for high yield targets. This offers an opportunity to study the effect ionization zones have on ion energies. We measure that ions have generally higher energies when ionization zones are present, supporting the concept that these zones are associated with moving potential humps. We propose that the disappearance of ionization zones is caused by an increased supply of atoms from the target which cools electrons and reduces depletion of atoms to be ionized.

  6. [Relationship among inattentive and hyperactive-impulsive behavior, aggression, and depression in Japanese elementary and junior high school students].

    PubMed

    Noda, Wataru; Okada, Ryo; Tani, Iori; Ohnishi, Masafumi; Naoto, Mochizuki; Nakajima, Syunji; Tsujii, Masatsugu

    2013-06-01

    The present study examines the relationship among inattentive, and hyperactive-impulsive behavior, aggression, and depression in elementary school and junior high school students. The participants were 3,885 children and their teachers and caregivers. Children's inattentive and hyperactive-impulsive behavior was rated by their teachers and caregivers (ADHD-RS). Children rated aggression (HAQ-C) and depression (DSRS-C) themselves. Inattentive and hyperactive-impulsive behavior rated by teachers and caregivers were positively related to aggression and depression. Inattention predicted higher levels of aggression and depression. Inattentive and hyperactive-impulsive behavior as rated by teachers was more highly related to depression than those behaviors as rated by caregivers. The relationships among inattentive, and hyperactive-impulsive behavior, aggression, and depression were almost the same for both elementary school and junior high school students. This study suggests the importance of assessing inattentive and hyperactive-impulsive behavior from multiple views to examine the relationship between inattentive and hyperactive-impulsive behavior and mental health problems.

  7. fMRI investigation of response inhibition, emotion, impulsivity, and clinical high-risk behavior in adolescents

    PubMed Central

    Brown, Matthew R. G.; Benoit, James R. A.; Juhás, Michal; Dametto, Ericson; Tse, Tiffanie T.; MacKay, Marnie; Sen, Bhaskar; Carroll, Alan M.; Hodlevskyy, Oleksandr; Silverstone, Peter H.; Dolcos, Florin; Dursun, Serdar M.; Greenshaw, Andrew J.

    2015-01-01

    High-risk behavior in adolescents is associated with injury, mental health problems, and poor outcomes in later life. Improved understanding of the neurobiology of high-risk behavior and impulsivity shows promise for informing clinical treatment and prevention as well as policy to better address high-risk behavior. We recruited 21 adolescents (age 14–17) with a wide range of high-risk behavior tendencies, including medically high-risk participants recruited from psychiatric clinics. Risk tendencies were assessed using the Adolescent Risk Behavior Screen (ARBS). ARBS risk scores correlated highly (0.78) with impulsivity scores from the Barratt Impulsivity scale (BIS). Participants underwent 4.7 Tesla functional magnetic resonance imaging (fMRI) while performing an emotional Go/NoGo task. This task presented an aversive or neutral distractor image simultaneously with each Go or NoGo stimulus. Risk behavior and impulsivity tendencies exhibited similar but not identical associations with fMRI activation patterns in prefrontal brain regions. We interpret these results as reflecting differences in response inhibition, emotional stimulus processing, and emotion regulation in relation to participant risk behavior tendencies and impulsivity levels. The results are consistent with high impulsivity playing an important role in determining high risk tendencies in this sample containing clinically high-risk adolescents. PMID:26483645

  8. Characteristics of corona impulses from insulated wires subjected to high ac voltages

    NASA Technical Reports Server (NTRS)

    Doreswamy, C. V.; Crowell, C. S.

    1976-01-01

    Corona discharges arise due to ionization of air or gas subject to high electric fields. The free electrons and ions contained in these discharges interact with molecules of insulating materials, resulting in chemical changes and destroying the electrical insulating properties. The paper describes some results of measurements aimed at determining corona pulse waveforms, their repetition rate, and amplitude distribution during various randomly-sampled identical time periods of a 60-Hz high-voltage wave. Described are properties of positive and negative corona impulses generated from typical conductors at various test high voltages. A possible method for calculating the energies, densities, and electromagnetic interferences by making use of these results is suggested.

  9. Characteristics of corona impulses from insulated wires subjected to high ac voltages

    NASA Technical Reports Server (NTRS)

    Doreswamy, C. V.; Crowell, C. S.

    1976-01-01

    Corona discharges arise due to ionization of air or gas subject to high electric fields. The free electrons and ions contained in these discharges interact with molecules of insulating materials, resulting in chemical changes and destroying the electrical insulating properties. The paper describes some results of measurements aimed at determining corona pulse waveforms, their repetition rate, and amplitude distribution during various randomly-sampled identical time periods of a 60-Hz high-voltage wave. Described are properties of positive and negative corona impulses generated from typical conductors at various test high voltages. A possible method for calculating the energies, densities, and electromagnetic interferences by making use of these results is suggested.

  10. Triple monoamine uptake inhibitors demonstrate a pharmacologic association between excessive drinking and impulsivity in high alcohol-preferring (HAP) mice

    PubMed Central

    O’Tousa, David S.; Warnock, Kaitlin T.; Matson, Liana M.; Namjoshi, Ojas A.; Halcomb, Meredith E.; Cook, James; Grahame, Nicholas J.; June, Harry L.

    2013-01-01

    Approximately 30% of current drinkers in the US drink excessively, and are referred to as problem/hazardous drinkers. These individuals, who may not meet criteria for alcohol abuse or dependence, comprise binge, heavy drinkers, or both. Given their high prevalence, interventions that reduce the risk of binge and heavy drinking have important public health implications. Impulsivity has been repeatedly associated with excessive drinking in the clinical literature. As impulsivity is correlated with, and may play a critical role in the initiation and maintenance of excessive drinking, this behavior may be an important target for therapeutic intervention. Hence, a better understanding of pharmacological treatments capable of attenuating excessive drinking models and impulsivity may markedly improve clinical outcomes. The high alcohol-preferring (HAP) mice represent an optimal rodent model to study the relationship between impulsivity and excessive alcohol drinking, as recent evidence indicates they consume high levels of alcohol throughout their active cycle and are innately impulsive. Using this model, the present study demonstrates that the triple monoamine uptake inhibitors (TUIs) amitifadine and DOV 102, 677 effectively attenuate binge drinking, heavy drinking assessed via a 24-hour free-choice assay, and impulsivity measured by the delay discounting procedure. In contrast, 3-PBC, a GABA-A α1 preferring ligand, with mixed agonist-antagonist properties attenuates excessive drinking without affecting impulsivity. These findings suggest in the HAP mice, monoamine pathways may predominate as a common mechanism underlying impulsivity and excessive drinking, while the GABAergic system may be more salient in regulating excessive drinking. We further propose that TUIs such as amitifadine and DOV 102, 677 may be used to treat the co-occurrence of impulsivity and excessive drinking. PMID:24118509

  11. Pay attention to impulsivity: modelling low attentive and high impulsive subtypes of adult ADHD in the 5-choice continuous performance task (5C-CPT) in female rats.

    PubMed

    Tomlinson, Anneka; Grayson, Ben; Marsh, Samuel; Harte, Michael K; Barnes, Samuel A; Marshall, Kay M; Neill, Joanna C

    2014-08-01

    Varying levels of attention and impulsivity deficits are core features of the three subtypes of adult attention deficit-hyperactivity disorder (ADHD). To date, little is known about the neurobiological correlates of these subtypes. Development of a translational animal model is essential to improve our understanding and improve therapeutic strategies. The 5-choice continuous performance task (5C-CPT) in rats can be used to examine different forms of attention and impulsivity. Adult rats were trained to pre-set 5C-CPT criterion and subsequently separated into subgroups according to baseline levels of sustained attention, vigilance, premature responding and response disinhibition in the 5C-CPT. The behavioural subgroups were selected to represent the different subtypes of adult ADHD. Consequently, effects of the clinically used pharmacotherapies (methylphenidate and atomoxetine) were assessed in the different subgroups. Four subgroups were identified: low-attentive (LA), high-attentive (HA), high-impulsive (HI) and low-impulsive (LI). Methylphenidate and atomoxetine produced differential effects in the subgroups. Methylphenidate increased sustained attention and vigilance in LA animals, and reduced premature responding in HI animals. Atomoxetine also improved sustained attention and vigilance in LA animals, and reduced response disinhibition and premature responding in HI animals. This is the first study using adult rats to demonstrate the translational value of the 5C-CPT to select subgroups of rats, which may be used to model the subtypes observed in adult ADHD. Our findings suggest that this as an important paradigm to increase our understanding of the neurobiological underpinnings of adult ADHD-subtypes and their response to pharmacotherapy.

  12. High-Resolution Analysis of Seismic Air Gun Impulses and Their Reverberant Field as Contributors to an Acoustic Environment.

    PubMed

    Guerra, Melania; Dugan, Peter J; Ponirakis, Dimitri W; Popescu, Marian; Shiu, Yu; Rice, Aaron N; Clark, Christopher W

    2016-01-01

    In September and October 2011, a seismic survey took place in Baffin Bay, Western Greenland, in close proximity to a marine protected area (MPA). As part of the mitigation effort, five bottom-mounted marine acoustic recording units (MARUs) collected data that were used for the purpose of measuring temporal and spectral features from each impulsive event, providing a high-resolution record of seismic reverberation persistent after the direct impulse. Results were compared with ambient-noise levels as computed after the seismic survey to evidence that as a consequence of a series of repeating seismic impulses, sustained elevated levels create the potential for masking.

  13. Family history of suicide and high motor impulsivity distinguish suicide attempters from suicide ideators among college students.

    PubMed

    Wang, Yong-Guang; Chen, Shen; Xu, Zhi-Ming; Shen, Zhi-Hua; Wang, Yi-Quan; He, Xiao-Yan; Cao, Ri-Fang; Roberts, David L; Shi, Jian-Fei; Wang, Yi-Qiang

    2017-02-08

    Suicide in college students has become an important public health issue in China. The aim of this study was to identify the differences between suicide attempters and suicide ideators based on a cross-sectional survey. Our results indicate that although female gender, positive screening for psychiatric illness, positive family history of suicide, elevated overall impulsivity, and elevated motor impulsivity were correlated with suicidal ideation, only positive family history of suicide and high motor impulsivity could differentiate suicide attempters from suicidal ideators. Future research with a longitudinal and prospective study design should be conducted to confirm these findings.

  14. Genetics of impulsive behaviour.

    PubMed

    Bevilacqua, Laura; Goldman, David

    2013-01-01

    Impulsivity, defined as the tendency to act without foresight, comprises a multitude of constructs and is associated with a variety of psychiatric disorders. Dissecting different aspects of impulsive behaviour and relating these to specific neurobiological circuits would improve our understanding of the etiology of complex behaviours for which impulsivity is key, and advance genetic studies in this behavioural domain. In this review, we will discuss the heritability of some impulsivity constructs and their possible use as endophenotypes (heritable, disease-associated intermediate phenotypes). Several functional genetic variants associated with impulsive behaviour have been identified by the candidate gene approach and re-sequencing, and whole genome strategies can be implemented for discovery of novel rare and common alleles influencing impulsivity. Via deep sequencing an uncommon HTR2B stop codon, common in one population, was discovered, with implications for understanding impulsive behaviour in both humans and rodents and for future gene discovery.

  15. Genetics of impulsive behaviour

    PubMed Central

    Bevilacqua, Laura; Goldman, David

    2013-01-01

    Impulsivity, defined as the tendency to act without foresight, comprises a multitude of constructs and is associated with a variety of psychiatric disorders. Dissecting different aspects of impulsive behaviour and relating these to specific neurobiological circuits would improve our understanding of the etiology of complex behaviours for which impulsivity is key, and advance genetic studies in this behavioural domain. In this review, we will discuss the heritability of some impulsivity constructs and their possible use as endophenotypes (heritable, disease-associated intermediate phenotypes). Several functional genetic variants associated with impulsive behaviour have been identified by the candidate gene approach and re-sequencing, and whole genome strategies can be implemented for discovery of novel rare and common alleles influencing impulsivity. Via deep sequencing an uncommon HTR2B stop codon, common in one population, was discovered, with implications for understanding impulsive behaviour in both humans and rodents and for future gene discovery. PMID:23440466

  16. High power impulse magnetron sputtering discharges: Instabilities and plasma self-organization

    SciTech Connect

    Ehiasarian, A. P.; New, R.; Hecimovic, A.; Arcos, T. de los; Schulz-von der Gathen, V.; Boeke, M.; Winter, J.

    2012-03-12

    We report on instabilities in high power impulse magnetron sputtering plasmas which are likely to be of the generalized drift wave type. They are characterized by well defined regions of high and low plasma emissivity along the racetrack of the magnetron and cause periodic shifts in floating potential. The azimuthal mode number m depends on plasma current, plasma density, and gas pressure. The structures rotate in E-vectorxB-vector direction at velocities of {approx}10 km s{sup -1} and frequencies up to 200 kHz. Collisions with residual gas atoms slow down the rotating wave, whereas increasing ionization degree of the gas and plasma conductivity speeds it up.

  17. Energy spectrum of corona impulses generated from insulated wires under high a.c. voltages

    NASA Technical Reports Server (NTRS)

    Doreswamy, C. V.; Padiyar, K. R.; Crowell, C. S.

    1978-01-01

    This paper suggests methods for calculating spectral energy densities of corona impulses generated from insulated conductors. The calculation is based on the data obtained from the measurement of corona pulse waveforms, repetition rates and relevant statistical properties of corona impulses.

  18. Influence of High-Current-Density Impulses on the Compression Behavior: Experiments with Iron and a Nickel-Based Alloy

    NASA Astrophysics Data System (ADS)

    Demler, E.; Gerstein, G.; Dalinger, A.; Epishin, A.; Rodman, D.; Nürnberger, F.

    2017-01-01

    Difficulties of processing of high strength and/or brittle materials by plastic deformation, e.g., by forging, require to develop new industrial technologies. In particular, the feasible deformation rates are limited for low-ductile metallic materials. For this reason, processes were investigated to improve the deformability in which electrical impulses are to be applied to lower the yield strength. However, owing to the impulse duration and low current densities, concomitant effects always occur, e.g., as a result of Joule heating. Current developments in power electronics allow now to transmit high currents as short pulses. By reducing the impulse duration and increasing the current density, the plasticity of metallic materials can be correspondingly increased. Using the examples of polycrystalline iron and a single-crystal, nickel-based alloy (PWA 1480), current advances in the development of methods for forming materials by means of high-current-density impulses are demonstrated. For this purpose, appropriate specimens were loaded in compression and, using novel testing equipment, subjected to a current strength of 10 kA with an impulse duration of 2 ms. For a pre-defined strain, the test results show a significant decrease in the compressive stress during the compression test and a significant change in the dislocation distribution following the current impulse treatment.

  19. Influence of High-Current-Density Impulses on the Compression Behavior: Experiments with Iron and a Nickel-Based Alloy

    NASA Astrophysics Data System (ADS)

    Demler, E.; Gerstein, G.; Dalinger, A.; Epishin, A.; Rodman, D.; Nürnberger, F.

    2016-12-01

    Difficulties of processing of high strength and/or brittle materials by plastic deformation, e.g., by forging, require to develop new industrial technologies. In particular, the feasible deformation rates are limited for low-ductile metallic materials. For this reason, processes were investigated to improve the deformability in which electrical impulses are to be applied to lower the yield strength. However, owing to the impulse duration and low current densities, concomitant effects always occur, e.g., as a result of Joule heating. Current developments in power electronics allow now to transmit high currents as short pulses. By reducing the impulse duration and increasing the current density, the plasticity of metallic materials can be correspondingly increased. Using the examples of polycrystalline iron and a single-crystal, nickel-based alloy (PWA 1480), current advances in the development of methods for forming materials by means of high-current-density impulses are demonstrated. For this purpose, appropriate specimens were loaded in compression and, using novel testing equipment, subjected to a current strength of 10 kA with an impulse duration of 2 ms. For a pre-defined strain, the test results show a significant decrease in the compressive stress during the compression test and a significant change in the dislocation distribution following the current impulse treatment.

  20. Drifting potential humps in ionization zones: The ``propeller blades'' of high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Anders, André; Panjan, Matjaž; Franz, Robert; Andersson, Joakim; Ni, Pavel

    2013-09-01

    Ion energy distribution functions measured for high power impulse magnetron sputtering show features, such as a broad peak at several 10 eV with an extended tail, as well as asymmetry with respect to E ×B, where E and B are the local electric and magnetic field vectors, respectively. Here it is proposed that those features are due to the formation of a potential hump of several 10 V in each of the traveling ionization zones. Potential hump formation is associated with a negative-positive-negative space charge that naturally forms in ionization zones driven by energetic drifting electrons.

  1. Ground state atomic oxygen in high-power impulse magnetron sputtering: a quantitative study

    NASA Astrophysics Data System (ADS)

    Britun, Nikolay; Belosludtsev, Alexandr; Silva, Tiago; Snyders, Rony

    2017-02-01

    The ground state density of oxygen atoms in reactive high-power impulse magnetron sputtering discharges has been studied quantitatively. Both time-resolved and space-resolved measurements were conducted. The measurements were performed using two-photon absorption laser-induced fluorescence (TALIF), and calibrated by optical emission actinometry with multiple Ar emission lines. The results clarify the dynamics of the O ground state atoms in the discharge afterglow significantly, including their propagation and fast decay after the plasma pulse, as well as the influence of gas pressure, O2 admixture, etc.

  2. Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas

    SciTech Connect

    Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore; Andersson, Joakim; Ni, Pavel; Anders, Andre

    2013-07-17

    Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

  3. Plasma reactivity in high-power impulse magnetron sputtering through oxygen kinetics

    SciTech Connect

    Vitelaru, Catalin; Lundin, Daniel; Brenning, Nils; Minea, Tiberiu

    2013-09-02

    The atomic oxygen metastable dynamics in a Reactive High-Power Impulse Magnetron Sputtering (R-HiPIMS) discharge has been characterized using time-resolved diode laser absorption in an Ar/O{sub 2} gas mixture with a Ti target. Two plasma regions are identified: the ionization region (IR) close to the target and further out the diffusion region (DR), separated by a transition region. The μs temporal resolution allows identifying the main atomic oxygen production and destruction routes, which are found to be very different during the pulse as compared to the afterglow as deduced from their evolution in space and time.

  4. Breakage of Curved Copper Wires Caused by High Impulse Current of Lightning

    NASA Astrophysics Data System (ADS)

    Hu, Xiaobo; Inaba, Tsuginori; Kindersberger, Josef

    In past studies, after thin straight copper wires of 0.1mmφ were exposed to an impulse current, their temperature rose; they melted according to the specific pre-arcing Joule integral in an adiabatic state. However, in this study, we confirmed that thick straight copper wires of 1mmφ and over it were broken in a solid state before melting The effect of physical damage on copper wire performance was confirmed. The test data suggest that ohmic heating is the main reason for thin (less than 1mmφ) copper wire breakage in the experiments. However, the magnetic force and skin effect are primarily responsible for breaking thick copper wires rather than thermal failure, as previously thought. And the thicker the copper wires diameter was, the more noticeable the magnetic force and skin effect were. Then the impulse current was impressed through curved copper wires from 0.3mmφ to 2.0mmφ. Because of different breakage mechanism for thin and thick copper wires, the current-carrying capability of thin curved copper wires did not change comparing to that of straight ones. However, the current-carrying capability of thick copper wires greatly decreased when they were curved.

  5. Tridimensional Personality Questionnaire data on alcoholic violent offenders: specific connections to severe impulsive cluster B personality disorders and violent criminality

    PubMed Central

    Tikkanen, Roope; Holi, Matti; Lindberg, Nina; Virkkunen, Matti

    2007-01-01

    Background The validity of traditional categorical personality disorder diagnoses is currently re-evaluated from a continuous perspective, and the evolving DSM-V classification may describe personality disorders dimensionally. The utility of dimensional personality assessment, however, is unclear in violent offenders with severe personality pathology. Methods The temperament structure of 114 alcoholic violent offenders with antisocial personality disorder (ASPD) was compared to 84 offenders without ASPD, and 170 healthy controls. Inclusion occurred during a court-ordered mental examination preceded by homicide, assault, battery, rape or arson. Participants underwent assessment of temperament with the Tridimensional Personality Questionnaire (TPQ) and were diagnosed with DSM-III-R criteria. Results The typical temperament profile in violent offender having ASPD comprised high novelty seeking, high harm avoidance, and low reward dependence. A 21% minority scored low in trait harm avoidance. Results, including the polarized harm avoidance dimension, are in accordance with Cloninger's hypothesis of dimensional description of ASPD. The low harm avoidance offenders committed less impulsive violence than high harm avoidance offenders. High harm avoidance was associated with comorbid antisocial personality disorder and borderline personality disorder. Conclusion Results indicate that the DSM based ASPD diagnosis in alcoholic violent offenders associates with impulsiveness and high novelty seeking but comprises two different types of ASPD associated with distinct second-order traits that possibly explain differences in type of violent criminality. Low harm avoidance offenders have many traits in common with high scorers on the Hare Psychopathy Checklist-Revised (PCL-R). Results link high harm avoidance with broad personality pathology and argue for the usefulness of self-report questionnaires in clinical praxis. PMID:17662159

  6. Method and apparatus for generating seismic impulses using high pressure water pump as the energizing source

    SciTech Connect

    Chelminski, S.V.

    1980-11-18

    A powerful seismic impulse is generated in a body of water by a slug of water propelled from a seismic source by expanding pressurized gas, but the gas is retained in the source for use in subsequent firings. The seismic energy source, which is called a ''hydro gun'', is recharged by pumping an incompressible liquid, preferably, water, at high pressure into the gun to compress the retained pressurized gas. The hydro gun includes a firing cylinder, and a piston follower in the firing cylinder divides it into a liquid-charge chamber and a gas-propulsion chamber. The liquid-charge chamber is closed from liquid discharge ports by a shuttle which is held closed by the high pressure of gas in an operating chamber. By pumping an incompressible liquid into the liquid-charge chamber, the follower is forced to compress the pressurized gas which is trapped in the gas-propulsion chamber. Then, to trigger the source, the gas pressure in the operating chamber acting on a front surface of an operating piston of the shuttle is suddenly applied to the reverse surface of the operating piston. With the shuttle thus released, the compressed pressurized gas in the gas-propulsion chamber expands against the follower to propel the liquid in the liquid-charge chamber through the liquid discharge ports into the surrounding body of water for generating a powerful seismic impulse in the water.

  7. Experimental evidence of parametric decay processes in the variable specific impulse magnetoplasma rocket (VASIMR) helicon plasma source

    NASA Astrophysics Data System (ADS)

    Boswell, R. W.; Sutherland, O.; Charles, C.; Squire, J. P.; Chang Díaz, F. R.; Glover, T. W.; Jacobson, V. T.; Chavers, D. G.; Bengtson, R. D.; Bering, E. A.; Goulding, R. H.; Light, M.

    2004-11-01

    Decay waves have been observed in the megahertz range in the helium plasma generated by the variable specific impulse magnetoplasma rocket magnetoplasma thruster. They are measured using one of the tips of a triple probe connected to a 50 Ω input of a spectrum analyzer via a dc block (a small capacitor). The maximum amplitude of all waves is in the center of the plasma and does not appear correlated to the radial electron density or temperature profiles. The waves seem to be generated close to the helicon antenna that was 91 cm "upstream" from the measuring Langmuir probe. A possible explanation is parametric decay of the large amplitude helicon wave that also generates the plasma.

  8. Model helicopter rotor high-speed impulsive noise: Measured acoustics and blade pressures

    NASA Technical Reports Server (NTRS)

    Boxwell, D. A.; Schmitz, F. H.; Splettstoesser, W. R.; Schultz, K. J.

    1983-01-01

    A 1/17-scale research model of the AH-1 series helicopter main rotor was tested. Model-rotor acoustic and simultaneous blade pressure data were recorded at high speeds where full-scale helicopter high-speed impulsive noise levels are known to be dominant. Model-rotor measurements of the peak acoustic pressure levels, waveform shapes, and directively patterns are directly compared with full-scale investigations, using an equivalent in-flight technique. Model acoustic data are shown to scale remarkably well in shape and in amplitude with full-scale results. Model rotor-blade pressures are presented for rotor operating conditions both with and without shock-like discontinuities in the radiated acoustic waveform. Acoustically, both model and full-scale measurements support current evidence that above certain high subsonic advancing-tip Mach numbers, local shock waves that exist on the rotor blades ""delocalize'' and radiate to the acoustic far-field.

  9. Instantaneous Impulses.

    ERIC Educational Resources Information Center

    Erlichson, Herman

    2000-01-01

    Describes an experiment that extends Newton's instantaneous-impulse method of orbital analysis to a graphical method of orbit determination. Discusses the experiment's usefulness for teaching both horizontal projectile motion and instantaneous impulse. (WRM)

  10. Instantaneous Impulses.

    ERIC Educational Resources Information Center

    Erlichson, Herman

    2000-01-01

    Describes an experiment that extends Newton's instantaneous-impulse method of orbital analysis to a graphical method of orbit determination. Discusses the experiment's usefulness for teaching both horizontal projectile motion and instantaneous impulse. (WRM)

  11. Electric field and space charge distribution measurement in transformer oil struck by impulsive high voltage

    NASA Astrophysics Data System (ADS)

    Sima, Wenxia; Guo, Hongda; Yang, Qing; Song, He; Yang, Ming; Yu, Fei

    2015-08-01

    Transformer oil is widely used in power systems because of its excellent insulation properties. The accurate measurement of electric field and space charge distribution in transformer oil under high voltage impulse has important theoretical and practical significance, but still remains challenging to date because of its low Kerr constant. In this study, the continuous electric field and space charge distribution over time between parallel-plate electrodes in high-voltage pulsed transformer oil based on the Kerr effect is directly measured using a linear array photoelectrical detector. Experimental results demonstrate the applicability and reliability of this method. This study provides a feasible approach to further study the space charge effects and breakdown mechanisms in transformer oil.

  12. Time resolved tunable diode laser absoption spectroscopy of dual High Power Impulse Magnetron Sputtering discharges

    NASA Astrophysics Data System (ADS)

    Do, Hoang Tung; Stranak, Vitezslav; Hippler, Rainer

    2014-08-01

    Time-resolved measurements have been performed during dual High Power Impulse Magnetron Sputtering (dual-HiPIMS) with two cathodes in a closed magnetic field configuration. The dual-HiPIMS system, operated at a repetition frequency f = 100 Hz and duty cycle of 1 %, was equipped with two different metallic targets (Ti, Cu). The effect of a delay between subsequent pulses on argon excited atom density and temperature was investigated by means of tunable diode laser absorption spectroscopy. It is shown that the peak densities of pulses vary strongly with the delay. We observed an enhancement of metastable density due to pre-ionization effect but more effective than that is the contribution of metal atoms which have smaller ionization energy compare to that of buffer gas atom. Associate with the enhancement of density, the temporal variation of metastable atom temperature in the Cu pulse also transforms from those of low current pulse into the high current one.

  13. Steep front short duration low voltage impulse performance of distribution transformers

    SciTech Connect

    Burrage, L.M.; Veverka, E.F.; McConnell, B.W.

    1987-01-01

    An extensive literature search of steep front short duration (SFSD) impulse sources, their characteristics and effect on power system equipment has led to the specification of a test program to evaluate key apparatus and insulations. Distribution transformers, although not overly susceptible to impulse damage, have been selected as one of the candidate apparatus for low and high voltage SFSD impulse tests. This paper covers the low voltage SFSD impulse response of conventional oil insulated shell form and core form distribution transformers.

  14. Particle visualization in high-power impulse magnetron sputtering. I. 2D density mapping

    SciTech Connect

    Britun, Nikolay Palmucci, Maria; Konstantinidis, Stephanos; Snyders, Rony

    2015-04-28

    Time-resolved characterization of an Ar-Ti high-power impulse magnetron sputtering discharge has been performed. This paper deals with two-dimensional density mapping in the discharge volume obtained by laser-induced fluorescence imaging. The time-resolved density evolution of Ti neutrals, singly ionized Ti atoms (Ti{sup +}), and Ar metastable atoms (Ar{sup met}) in the area above the sputtered cathode is mapped for the first time in this type of discharges. The energetic characteristics of the discharge species are additionally studied by Doppler-shift laser-induced fluorescence imaging. The questions related to the propagation of both the neutral and ionized discharge particles, as well as to their spatial density distributions, are discussed.

  15. Are the argon metastables important in high power impulse magnetron sputtering discharges?

    SciTech Connect

    Gudmundsson, J. T.; Lundin, D.; Minea, T. M.; Stancu, G. D.; Brenning, N.

    2015-11-15

    We use an ionization region model to explore the ionization processes in the high power impulse magnetron sputtering (HiPIMS) discharge in argon with a titanium target. In conventional dc magnetron sputtering (dcMS), stepwise ionization can be an important route for ionization of the argon gas. However, in the HiPIMS discharge stepwise ionization is found to be negligible during the breakdown phase of the HiPIMS pulse and becomes significant (but never dominating) only later in the pulse. For the sputtered species, Penning ionization can be a significant ionization mechanism in the dcMS discharges, while in the HiPIMS discharge Penning ionization is always negligible as compared to electron impact ionization. The main reasons for these differences are a higher plasma density in the HiPIMS discharge, and a higher electron temperature. Furthermore, we explore the ionization fraction and the ionized flux fraction of the sputtered vapor and compare with recent experimental work.

  16. Particle visualization in high-power impulse magnetron sputtering. II. Absolute density dynamics

    SciTech Connect

    Britun, Nikolay Palmucci, Maria; Konstantinidis, Stephanos; Snyders, Rony

    2015-04-28

    Time-resolved characterization of an Ar-Ti high-power impulse magnetron sputtering discharge has been performed. The present, second, paper of the study is related to the discharge characterization in terms of the absolute density of species using resonant absorption spectroscopy. The results on the time-resolved density evolution of the neutral and singly-ionized Ti ground state atoms as well as the metastable Ti and Ar atoms during the discharge on- and off-time are presented. Among the others, the questions related to the inversion of population of the Ti energy sublevels, as well as to re-normalization of the two-dimensional density maps in terms of the absolute density of species, are stressed.

  17. A High-Power Reflector Impulse Antenna with Dual-Tem Source

    NASA Astrophysics Data System (ADS)

    Guo, Chen; Zhang, An-Xue; Wu, Hui; Jiang, Yan-Sheng; Wang, Wen-Bing

    2008-09-01

    There are different demands on radiation efficiency and direction pattern according to various ultra-wideband (UWB) antennas and high power applications. To obtain more radiating gain on bore-sight of paraboloidal reflector and centralized radiating direction, a novel feeding structure called dual-TEM source has been designed and applied in half-paraboloidal reflector impulse radiating antenna (IRA) applications. Simulation results proved that this proposed half-paraboloidal reflector IRA with dual-TEM source provided greater radiation performance on bore-sight as a result of the synthesized power in the aperture space of paraboloid. Moreover, lots of simulation work and comparison have been done in different feeding models to summarize a relative optimal feeding structure.

  18. Blunted cardiac stress reactors exhibit relatively high levels of behavioural impulsivity.

    PubMed

    Bibbey, Adam; Ginty, Annie T; Brindle, Ryan C; Phillips, Anna C; Carroll, Douglas

    2016-05-15

    Blunted physiological reactions to acute psychological stress are associated with a range of adverse health and behavioural outcomes. This study examined whether extreme stress reactors differ in their behavioural impulsivity. Individuals showing blunted (N=23) and exaggerated (N=23) cardiovascular reactions to stress were selected by screening a healthy student population (N=276). Behavioural impulsivity was measured via inhibitory control and motor impulsivity tasks. Blunted reactors exhibited greater impulsivity than exaggerated reactors on both stop-signal, F(1,41)=4.99, p=0.03, ηp(2)=0.108, and circle drawing, F(1,43)=4.00, p=0.05, η p(2)=0.085, tasks. Individuals showing blunted cardiovascular stress reactions are characterized by greater impulsivity which may contribute to their increased susceptibility to outcomes such as obesity and addiction.

  19. Highly impulsive rats: modelling an endophenotype to determine the neurobiological, genetic and environmental mechanisms of addiction

    PubMed Central

    Jupp, Bianca; Caprioli, Daniele; Dalley, Jeffrey W.

    2013-01-01

    Impulsivity describes the tendency of an individual to act prematurely without foresight and is associated with a number of neuropsychiatric co-morbidities, including drug addiction. As such, there is increasing interest in the neurobiological mechanisms of impulsivity, as well as the genetic and environmental influences that govern the expression of this behaviour. Tests used on rodent models of impulsivity share strong parallels with tasks used to assess this trait in humans, and studies in both suggest a crucial role of monoaminergic corticostriatal systems in the expression of this behavioural trait. Furthermore, rodent models have enabled investigation of the causal relationship between drug abuse and impulsivity. Here, we review the use of rodent models of impulsivity for investigating the mechanisms involved in this trait, and how these mechanisms could contribute to the pathogenesis of addiction. PMID:23355644

  20. Preliminary evaluation of the air and fuel specific-impulse characteristics of several potential ram-jet fuels IV : hydrogen, a-methylnaphthalene, and carbon / Benson E. Gammon

    NASA Technical Reports Server (NTRS)

    Gammon, Benson E

    1951-01-01

    A preliminary analytical evaluation of the air and fuel specific-impulse characteristics of hydrogen, a-methylnapthalene, and graphite carbon has been made. Adiabatic constant-pressure combustion flame temperatures for each fuel at several equivalence ratios were calculated for an initial air temperature of 560 degrees R and a pressure of 2 atmospheres.

  1. THE GENESIS OF AN IMPULSIVE CORONAL MASS EJECTION OBSERVED AT ULTRA-HIGH CADENCE BY AIA ON SDO

    SciTech Connect

    Patsourakos, S.; Vourlidas, A.; Stenborg, G.

    2010-12-01

    The study of fast, eruptive events in the low solar corona is one of the science objectives of the Atmospheric Imaging Assembly (AIA) imagers on the recently launched Solar Dynamics Observatory (SDO), which take full disk images in 10 wavelengths with arcsecond resolution and 12 s cadence. We study with AIA the formation of an impulsive coronal mass ejection (CME) which occurred on 2010 June 13 and was associated with an M1.0 class flare. Specifically, we analyze the formation of the CME EUV bubble and its initial dynamics and thermal evolution in the low corona using AIA images in three wavelengths (171 A, 193 A, and 211 A). We derive the first ultra-high cadence measurements of the temporal evolution of the CME bubble aspect ratio (=bubble height/bubble radius). Our main result is that the CME formation undergoes three phases: it starts with a slow self-similar expansion followed by a fast but short-lived ({approx}70 s) period of strong lateral overexpansion which essentially creates the CME. Then the CME undergoes another phase of self-similar expansion until it exits the AIA field of view. During the studied interval, the CME height-time profile shows a strong, short-lived, acceleration followed by deceleration. The lateral overexpansion phase coincides with the deceleration phase. The impulsive flare heating and CME acceleration are closely coupled. However, the lateral overexpansion of the CME occurs during the declining phase and is therefore not linked to flare reconnection. In addition, the multi-thermal analysis of the bubble does not show significant evidence of temperature change.

  2. Recombination processes in a flowing magnetized plasma: Application to ionization energy recovery in the variable specific impulse magnetoplasma rocket (VASIMR)

    NASA Astrophysics Data System (ADS)

    Chavers, Donald Gregory

    Electric propulsion involves the acceleration of charged particles (ions and electrons) through electric and magnetic body forces. The collection of these charged particles, or plasma, cannot be stored but must be created in-situ. Therefore, energy must be supplied to a neutral gas to create the plasma that is accelerated by the body forces. The energy that is used to create the plasma, i.e., ionization energy, is typically lost, "frozen" in the exhaust of the thruster. When the kinetic energy in the plasma flow is much larger than the energy used to create the plasma, this frozen-flow loss is negligible. Conversely, if the frozen-flow loss is a major fraction of the total plasma energy, its recovery, even in a partial way, may improve the energy efficiency of the thruster while also providing a potential means for thrust augmentation. This dissertation investigates the underlying physics, which could enable the practical recovery of frozen-flow losses by processes such as surface and volume recombination. For surface recombination, the ions approach the surface of the metal and are neutralized by electrons from the metal via the Auger neutralization process. For volume recombination, the ions and electrons recombine, with energy released via line radiation or by transferring energy to a third body such as another electron. Since the total energy of the neutralized ion, an atom, is less than the total energy of the ion and electron pair before recombination, conservation of energy requires the release of energy as the ion and electron recombine. The measurements described in this dissertation were performed on the VX-10 experiment, a plasma device supporting the development of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) concept and located at the Advanced Space Propulsion Laboratory of the Johnson Space Center. Results suggest that the recombination energy can be recovered. The available energy and power recovered depends on the local plasma

  3. Impulsivity and Academic Cheating

    ERIC Educational Resources Information Center

    Anderman, Eric M.; Cupp, Pamela K.; Lane, Derek

    2009-01-01

    The authors examined the relations between academic cheating and impulsivity in a large sample of adolescents enrolled in high school health education classes. Results indicated that impulsivity predicts academic cheating for students who report extensive involvement in cheating. However, students who engage in extensive cheating are less likely…

  4. Feasibility of Colliding-beam fast-fission reactor via 238U80++238 U80+ --> 4 FF + 5n + 430 MeV beam with suppressed plutonium and direct conversion of fission fragment (FF) energy into electricity and/or Rocket propellant with high specific impulse

    NASA Astrophysics Data System (ADS)

    Maglich, Bogdan; Hester, Tim; Calsec Collaboration

    2015-10-01

    Uranium-uranium colliding beam experiment1, used fully ionized 238U92+ at energy 100GeV --> <-- 100 GeV, has measured total σ = 487 b. Reaction rate of colliding beams is proportional to neutron flux-squared. First functional Auto-Collider3-6, a compact Migma IV, 1 m in diameter, had self-colliding deuterons, D+, of 725 KeV --> <-- 725 KeV, resulting in copious production of T and 3He. U +U Autocollider``EXYDER'' will use strong-focusing magnet7, which would increase reaction rate by 104. 80 times ionized U ions accelerated through 3 MV accelerator, will collide beam 240 MeV --> <-- 240 MeV. Reaction is: 238U80+ +238 U80+ --> 4 FF + 5n + 430 MeV. Using a simple model1 fission σf ~ 100 b. Suppression of Pu by a factor of 106 will be achieved because NO thermal neutron fission can take place; only fast, 1-3 MeV, where σabs is negligible. Direct conversion of 95% of 430 MeV produced is carried by electrically charged FFs which are magnetically funneled for direct conversion of energy of FFs via electrostatic decelerators4,11. 90% of 930 MeV is electrically recoverable. Depending on the assumptions, we project electric _ power density production of 20 to 200 MWe m-3, equivalent to Thermal 1.3 - 13 GWthm-3. If one-half of unburned U is used for propulsion while rest powers system, heavy FF ion mass provides specific impulse Isp = 106 sec., 103 times higher than current rocket engines.

  5. ZrN coatings deposited by high power impulse magnetron sputtering and cathodic arc techniques

    SciTech Connect

    Purandare, Yashodhan Ehiasarian, Arutiun; Hovsepian, Papken; Santana, Antonio

    2014-05-15

    Zirconium nitride (ZrN) coatings were deposited on 1 μm finish high speed steel and 316L stainless steel test coupons. Cathodic Arc (CA) and High Power Impulse Magnetron Sputtering (HIPIMS) + Unbalanced Magnetron Sputtering (UBM) techniques were utilized to deposit coatings. CA plasmas are known to be rich in metal and gas ions of the depositing species as well as macroparticles (droplets) emitted from the arc sports. Combining HIPIMS technique with UBM in the same deposition process facilitated increased ion bombardment on the depositing species during coating growth maintaining high deposition rate. Prior to coating deposition, substrates were pretreated with Zr{sup +} rich plasma, for both arc deposited and HIPIMS deposited coatings, which led to a very high scratch adhesion value (L{sub C2}) of 100 N. Characterization results revealed the overall thickness of the coatings in the range of 2.5 μm with hardness in the range of 30–40 GPa depending on the deposition technique. Cross-sectional transmission electron microscopy and tribological experiments such as dry sliding wear tests and corrosion studies have been utilized to study the effects of ion bombardment on the structure and properties of these coatings. In all the cases, HIPIMS assisted UBM deposited coating fared equal or better than the arc deposited coatings, the reasons being discussed in this paper. Thus H+U coatings provide a good alternative to arc deposited where smooth, dense coatings are required and macrodroplets cannot be tolerated.

  6. Impulsive action: emotional impulses and their control

    PubMed Central

    Frijda, Nico H.; Ridderinkhof, K. Richard; Rietveld, Erik

    2014-01-01

    This paper presents a novel theoretical view on impulsive action, integrating thus far separate perspectives on non-reflective action, motivation, emotion regulation, and impulse control. We frame impulsive action in terms of directedness of the individual organism toward, away, or against other givens – toward future states and away from one’s present state. First, appraisal of a perceived or thought-of event or object on occasion, rapidly and without premonition or conscious deliberation, triggers a motive to modify one’s relation to that event or object. Situational specifics of the event as perceived and appraised motivate and guide selection of readiness for a particular kind of purposive action. Second, perception of complex situations can give rise to multiple appraisals, multiple motives, and multiple simultaneous changes in action readiness. Multiple states of action readiness may interact in generating action, by reinforcing or attenuating each other, thereby yielding impulse control. We show how emotion control can itself result from a motive state or state of action readiness. Our view links impulsive action mechanistically to states of action readiness, which is the central feature of what distinguishes one kind of emotion from another. It thus provides a novel theoretical perspective to the somewhat fragmented literature on impulsive action. PMID:24917835

  7. Quality of life and impulsivity in bipolar disorder

    PubMed Central

    Victor, Sarah E; Johnson, Sheri L; Gotlib, Ian H

    2011-01-01

    Objectives Bipolar disorder (BD) is a chronic psychiatric illness that impairs quality of life (QoL) in numerous life domains even when mood symptoms are not present and is characterized by elevated impulsivity. Many of the comorbid conditions that are associated with diminished QoL in BD also involve impulsivity. The objective of this project was to investigate whether impulsivity might mediate the effects of these comorbid conditions on poor QoL. Methods A total of 76 participants diagnosed with bipolar I disorder by the Structured Clinical Interview for DSM-IV Axis I disorders completed the Quality of Life in Bipolar Disorder (QoL-BD) scale, the Barratt Impulsivity Scale (BIS-11), and the Positive Urgency Measure (PUM). Participants were also assessed for comorbid DSM-IV diagnoses of anxiety, substance use, and impulse control disorders. Results Several subscales of the BIS-11 as well as the PUM total score were significantly negatively correlated with overall QoL. PUM total score remained a significant predictor of QoL after controlling for comorbid anxiety, substance use, and impulse control disorders. After controlling for impulsivity, comorbid disorders were no longer significantly related to overall QoL. Conclusions The data support the hypothesis that impulsivity, specifically positive urgency, is highly correlated with QoL in BD. Impulsivity was found to mediate the relation between QoL and several comorbidities in BD. Interventions targeting impulsivity might help to improve QoL in BD. PMID:21676133

  8. Novel high power impulse magnetron sputtering enhanced by an auxiliary electrical field.

    PubMed

    Li, Chunwei; Tian, Xiubo

    2016-08-01

    The high power impulse magnetron sputtering (HIPIMS) technique is a novel highly ionized physical vapor deposition method with a high application potential. However, the electron utilization efficiency during sputtering is rather low and the metal particle ionization rate needs to be considerably improved to allow for a large-scale industrial application. Therefore, we enhanced the HIPIMS technique by simultaneously applying an electric field (EF-HIPIMS). The effect of the electric field on the discharge process was studied using a current sensor and an optical emission spectrometer. Furthermore, the spatial distribution of the electric potential and electric field during the EF-HIPIMS process was simulated using the ANSYS software. The results indicate that a higher electron utilization efficiency and a higher particle ionization rate could be achieved. The auxiliary anode obviously changed the distribution of the electric potential and the electric field in the discharge region, which increased the plasma density and enhanced the degree of ionization of the vanadium and argon gas. Vanadium films were deposited to further compare both techniques, and the morphology of the prepared films was investigated by scanning electron microscopy. The films showed a smaller crystal grain size and a denser growth structure when the electric field was applied during the discharge process.

  9. Spatial and temporal evolution of ion energies in high power impulse magnetron sputtering plasma discharge

    NASA Astrophysics Data System (ADS)

    Hecimovic, A.; Ehiasarian, A. P.

    2010-09-01

    High power impulse magnetron sputtering (HIPIMS) is a novel deposition technology successfully implemented on full scale industrial machines. HIPIMS utilizes short pulses of high power delivered to the target in order to generate high amount of metal ions. The life-span of ions between the pulses and their energy distribution could strongly influence the properties and characteristics of the deposited coating. In modern industrial coating machines the sample rotates on a substrate holder and changes its position and distance with regard to the magnetron. Time resolved measurements of the ion energy distribution function (IEDF) at different distances from the magnetron have been performed to investigate the temporal evolution of ions at various distances from target. The measurements were performed using two pressures, 1 and 3 Pa to investigate the influence of working gas pressure on IEDF. Plasma sampling energy-resolved mass spectroscopy was used to measure the IEDF of Ti1+, Ti2+, Ar1+, and Ar2+ ions in HIPIMS plasma discharge with titanium (Ti) target in Ar atmosphere. The measurements were done over a full pulse period and the distance between the magnetron and the orifice of the mass spectrometer was changed from 25 to 215 mm.

  10. Novel high power impulse magnetron sputtering enhanced by an auxiliary electrical field

    NASA Astrophysics Data System (ADS)

    Li, Chunwei; Tian, Xiubo

    2016-08-01

    The high power impulse magnetron sputtering (HIPIMS) technique is a novel highly ionized physical vapor deposition method with a high application potential. However, the electron utilization efficiency during sputtering is rather low and the metal particle ionization rate needs to be considerably improved to allow for a large-scale industrial application. Therefore, we enhanced the HIPIMS technique by simultaneously applying an electric field (EF-HIPIMS). The effect of the electric field on the discharge process was studied using a current sensor and an optical emission spectrometer. Furthermore, the spatial distribution of the electric potential and electric field during the EF-HIPIMS process was simulated using the ANSYS software. The results indicate that a higher electron utilization efficiency and a higher particle ionization rate could be achieved. The auxiliary anode obviously changed the distribution of the electric potential and the electric field in the discharge region, which increased the plasma density and enhanced the degree of ionization of the vanadium and argon gas. Vanadium films were deposited to further compare both techniques, and the morphology of the prepared films was investigated by scanning electron microscopy. The films showed a smaller crystal grain size and a denser growth structure when the electric field was applied during the discharge process.

  11. Novel high power impulse magnetron sputtering enhanced by an auxiliary electrical field

    SciTech Connect

    Li, Chunwei E-mail: xiubotian@163.com; Tian, Xiubo E-mail: xiubotian@163.com

    2016-08-15

    The high power impulse magnetron sputtering (HIPIMS) technique is a novel highly ionized physical vapor deposition method with a high application potential. However, the electron utilization efficiency during sputtering is rather low and the metal particle ionization rate needs to be considerably improved to allow for a large-scale industrial application. Therefore, we enhanced the HIPIMS technique by simultaneously applying an electric field (EF-HIPIMS). The effect of the electric field on the discharge process was studied using a current sensor and an optical emission spectrometer. Furthermore, the spatial distribution of the electric potential and electric field during the EF-HIPIMS process was simulated using the ANSYS software. The results indicate that a higher electron utilization efficiency and a higher particle ionization rate could be achieved. The auxiliary anode obviously changed the distribution of the electric potential and the electric field in the discharge region, which increased the plasma density and enhanced the degree of ionization of the vanadium and argon gas. Vanadium films were deposited to further compare both techniques, and the morphology of the prepared films was investigated by scanning electron microscopy. The films showed a smaller crystal grain size and a denser growth structure when the electric field was applied during the discharge process.

  12. Evolution of sputtering target surface composition in reactive high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Kubart, T.; Aijaz, A.

    2017-05-01

    The interaction between pulsed plasmas and surfaces undergoing chemical changes complicates physics of reactive High Power Impulse Magnetron Sputtering (HiPIMS). In this study, we determine the dynamics of formation and removal of a compound on a titanium surface from the evolution of discharge characteristics in an argon atmosphere with nitrogen and oxygen. We show that the time response of a reactive process is dominated by surface processes. The thickness of the compound layer is several nm and its removal by sputtering requires ion fluence in the order of 1016 cm-2, much larger than the ion fluence in a single HiPIMS pulse. Formation of the nitride or oxide layer is significantly slower in HiPIMS than in dc sputtering under identical conditions. Further, we explain very high discharge currents in HiPIMS by the formation of a truly stoichiometric compound during the discharge off-time. The compound has a very high secondary electron emission coefficient and leads to a large increase in the discharge current upon target poisoning.

  13. Plasma"anti-assistance" and"self-assistance" to high power impulse magnetron sputtering

    SciTech Connect

    Anders, Andre; Yushkov, Georgy Yu.

    2009-01-30

    A plasma assistance system was investigated with the goal to operate high power impulse magnetron sputtering (HiPIMS) at lower pressure than usual, thereby to enhance the utilization of the ballistic atoms and ions with high kinetic energy in the film growth process. Gas plasma flow from a constricted plasma source was aimed at the magnetron target. Contrary to initial expectations, such plasma assistance turned out to be contra-productive because it led to the extinction of the magnetron discharge. The effect can be explained by gas rarefaction. A better method of reducing the necessary gas pressure is operation at relatively high pulse repetition rates where the afterglow plasma of one pulse assists in the development of the next pulse. Here we show that this method, known from medium-frequency (MF) pulsed sputtering, is also very important at the much lower pulse repetition rates of HiPIMS. A minimum in the possible operational pressure is found in the frequency region between HiPIMS and MF pulsed sputtering.

  14. Study of the Helicon Source Operation in the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) Experiment

    NASA Technical Reports Server (NTRS)

    Molvig, Kim; Batishchev, Oleg

    2003-01-01

    During this research period the following models of the VASIMR helicon discharge have been further developed and applied to analyze the on-going VX- 10 ASPL experiment: A) 1D semi-analytical model for a mixed-collisional propellant flow B) OD power and balance model for the whole helicon discharge In this particular research period we have concentrated on the MW-level performance of the VASIMR helicon source. Favorable high-power scaling and reduced ionization costs were obtained, and presented at the VASIMR NASA review in the Fall '02. This Grant is continuation of the previous NAG9-1224 award. The research results are summarized in 14 publications; they were presented as 20+ talks at the major International Conferences and scientific seminars at the leading Academic and Research Institutions. The reported results allowed helicon discharge characterization, understanding of the several experimental observations, and helped to make predictions and propose structural modifications for the advanced VASIMR helicon source operation.

  15. High specific heat superconducting composite

    DOEpatents

    Steyert, Jr., William A.

    1979-01-01

    A composite superconductor formed from a high specific heat ceramic such as gadolinium oxide or gadolinium-aluminum oxide and a conventional metal conductor such as copper or aluminum which are insolubly mixed together to provide adiabatic stability in a superconducting mode of operation. The addition of a few percent of insoluble gadolinium-aluminum oxide powder or gadolinium oxide powder to copper, increases the measured specific heat of the composite by one to two orders of magnitude below the 5.degree. K. level while maintaining the high thermal and electrical conductivity of the conventional metal conductor.

  16. Origin of the Delayed Current Onset in High Power Impulse Magnetron Sputtering

    SciTech Connect

    Yushkov, Georgy Yu.; Anders, Andre

    2010-07-19

    Repetitive pulses of voltage and current are applied in high power impulse magnetron sputtering. The current pulse usually lags the applied voltage by a significant time, which in some cases can reach many 10s of microseconds. The current time lag is generally highly reproducible and jitters less than 1percent of the delay time. This work investigates the time lag experimentally and theoretically. The experiments include several different target and gas combinations, voltage and current amplitudes, gas pressures, pulse repetition rates, and pulse durations. It is shown that in all cases the inverse delay is approximately proportional to the applied voltage, where the proportionality factor depends on the combination of materials and the conditions selected. The proportionality factor contains the parameters of ionization and secondary electron emission. The statistical time lag is negligible while the formative time lag is large and usually dominated by the ion motion (inertia), although, at low pressure, the long free path of magnetized electrons causing ionization contributes to the delay.

  17. Duty cycle control in reactive high-power impulse magnetron sputtering of hafnium and niobium

    NASA Astrophysics Data System (ADS)

    Ganesan, R.; Treverrow, B.; Murdoch, B.; Xie, D.; Ross, A. E.; Partridge, J. G.; Falconer, I. S.; McCulloch, D. G.; McKenzie, D. R.; Bilek, M. M. M.

    2016-06-01

    Instabilities in reactive sputtering have technological consequences and have been attributed to the formation of a compound layer on the target surface (‘poisoning’). Here we demonstrate how the duty cycle of high power impulse magnetron sputtering (HiPIMS) can be used to control the surface conditions of Hf and Nb targets. Variations in the time resolved target current characteristics as a function of duty cycle were attributed to gas rarefaction and to the degree of poisoning of the target surface. As the operation transitions from Ar driven sputtering to metal driven sputtering, the secondary electron emission changes and reduces the target current. The target surface transitions smoothly from a poisoned state at low duty cycles to a quasi-metallic state at high duty cycles. Appropriate selection of duty cycle increases the deposition rate, eliminates the need for active regulation of oxygen flow and enables stable reactive deposition of stoichiometric metal oxide films. A model is presented for the reactive HIPIMS process in which the target operates in a partially poisoned mode with different degrees of oxide layer distribution on its surface that depends on the duty cycle. Finally, we show that by tuning the pulse characteristics, the refractive indices of the metal oxides can be controlled without increasing the absorption coefficients, a result important for the fabrication of optical multilayer stacks.

  18. Species transport on the target during high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Layes, V.; Monje, S.; Corbella, C.; Trieschmann, J.; de los Arcos, T.; von Keudell, A.

    2017-02-01

    High Power Impulse Magnetron Sputtering (HiPIMS) is a prominent technique to deposit superior materials due to the very energetic growth flux. The origin of this energetic growth flux is believed to be an electric potential structure inside localized ionization zones, the so-called spokes, in the HiPIMS plasma, which rotate in the E × B direction along the racetrack. The measurement of this electric potential or of the electric fields surrounding this ionization zone is extremely challenging due to the very high local power density that obstructs any traditional probe diagnostics. Here, we use a marker technique on the magnetron target to analyze the lateral transport of a target material on a HiPIMS target. We show that the target material is predominantly transported in the E × B direction irrespective of the presence of spokes. However, only when spokes are present, we observe also an enhanced transport in the opposite E × B direction. This is explained by the large electric field at the trailing edges of spokes.

  19. Codeposition of amorphous zinc tin oxide using high power impulse magnetron sputtering: characterisation and doping

    NASA Astrophysics Data System (ADS)

    Tran, H. N.; Mayes, E. L. H.; Murdoch, B. J.; McCulloch, D. G.; McKenzie, D. R.; Bilek, M. M. M.; Holland, A. S.; Partridge, J. G.

    2017-04-01

    Thin film zinc tin oxide (ZTO) has been energetically deposited at 100 °C using high power impulse magnetron sputtering (HiPIMS). Reactive co-deposition from Zn (HiPIMS mode) and Sn (DC magnetron sputtering mode) targets yielded a gradient in the Zn:Sn ratio across a 4-inch diameter sapphire substrate. The electrical and optical properties of the film were studied as a function of composition. As-deposited, the films were amorphous, transparent and semi-insulating. Hydrogen was introduced by post-deposition annealing (1 h, 500 °C, 100 mTorr H2) and resulted in significantly increased conductivity with no measurable structural alterations. After annealing, Hall effect measurements revealed n-type carrier concentrations of ˜1 × 1017 cm-3 and mobilities of up to 13 cm2 V-1 s-1. These characteristics are suitable for device applications and proved stable. X-ray photoelectron spectroscopy was used to explore the valence band structure and to show that downward surface band-bending resulted from OH attachment. The results suggest that HiPIMS can produce dense, high quality amorphous ZTO suitable for applications including transparent thin film transistors.

  20. Deposition Rates of High Power Impulse Magnetron Sputtering: Physics and Economics

    SciTech Connect

    Anders, Andre

    2009-11-22

    Deposition by high power impulse magnetron sputtering (HIPIMS) is considered by some as the new paradigm of advanced sputtering technology, yet this is met with skepticism by others for the reported lower deposition rates, if compared to rates of more conventional sputtering of equal average power. In this contribution, the underlying physical reasons for the rate changes are discussed, including (i) ion return to the target and self-sputtering, (ii) the less-than-linear increase of the sputtering yield with increasing ion energy, (iii) yield changes due to the shift of species responsible for sputtering, (iv) changes to due to greater film density, limited sticking, and self-sputtering on the substrate, (v) noticeable power losses in the switch module, (vi) changes of the magnetic balance and particle confinement of the magnetron due to self-fields at high current, and (vii) superposition of sputtering and sublimation/evaporation for selected materials. The situation is even more complicated for reactive systems where the target surface chemistry is a function of the reactive gas partial pressure and discharge conditions. While most of these factors imply a reduction of the normalized deposition rate, increased rates have been reported for certain conditions using hot targets and less poisoned targets. Finally, some points of economics and HIPIMS benefits considered.

  1. Deposition rates of high power impulse magnetron sputtering: Physics and economics

    SciTech Connect

    Anders, Andre

    2010-07-15

    Deposition by high power impulse magnetron sputtering (HIPIMS) is considered by some as the new paradigm of advanced sputtering technology, yet this is met with skepticism by others for the reported lower deposition rates, if compared to rates of more conventional sputtering of equal average power. In this contribution, the underlying physical reasons for the rate changes are discussed, including (i) ion return to the target and self-sputtering, (ii) the less-than-linear increase in the sputtering yield with increasing ion energy, (iii) yield changes due to the shift of species responsible for sputtering, (iv) changes due to greater film density, limited sticking, and self-sputtering on the substrate, (v) noticeable power losses in the switch module, (vi) changes in the magnetic balance and particle confinement of the magnetron due to self-fields at high current, and (vii) superposition of sputtering and sublimation/evaporation for selected materials. The situation is even more complicated for reactive systems where the target surface chemistry is a function of the reactive gas partial pressure and discharge conditions. While most of these factors imply a reduction in the normalized deposition rate, increased rates have been reported for certain conditions using hot targets and less poisoned targets. Finally, some points of economics and HIPIMS benefits are considered.

  2. Acoustic radiation force impulse (ARFI) imaging of zebrafish embryo by high-frequency coded excitation sequence.

    PubMed

    Park, Jinhyoung; Lee, Jungwoo; Lau, Sien Ting; Lee, Changyang; Huang, Ying; Lien, Ching-Ling; Kirk Shung, K

    2012-04-01

    Acoustic radiation force impulse (ARFI) imaging has been developed as a non-invasive method for quantitative illustration of tissue stiffness or displacement. Conventional ARFI imaging (2-10 MHz) has been implemented in commercial scanners for illustrating elastic properties of several organs. The image resolution, however, is too coarse to study mechanical properties of micro-sized objects such as cells. This article thus presents a high-frequency coded excitation ARFI technique, with the ultimate goal of displaying elastic characteristics of cellular structures. Tissue mimicking phantoms and zebrafish embryos are imaged with a 100-MHz lithium niobate (LiNbO₃) transducer, by cross-correlating tracked RF echoes with the reference. The phantom results show that the contrast of ARFI image (14 dB) with coded excitation is better than that of the conventional ARFI image (9 dB). The depths of penetration are 2.6 and 2.2 mm, respectively. The stiffness data of the zebrafish demonstrate that the envelope is harder than the embryo region. The temporal displacement change at the embryo and the chorion is as large as 36 and 3.6 μm. Consequently, this high-frequency ARFI approach may serve as a remote palpation imaging tool that reveals viscoelastic properties of small biological samples.

  3. Antimicrobial brass coatings prepared on poly(ethylene terephthalate) textile by high power impulse magnetron sputtering.

    PubMed

    Chen, Ying-Hung; Wu, Guo-Wei; He, Ju-Liang

    2015-03-01

    The goal of this work is to prepare antimicrobial, corrosion-resistant and low-cost Cu65Zn35 brass film on poly(ethylene terephthalate) (PET) fabric by high-power impulse magnetron sputtering (HIPIMS), which is known to provide high-density plasma, so as to generate a strongly adherent film at a reduced substrate temperature. The results reveal that the brass film grows in a layer-plus-island mode. Independent of their deposition time, the obtained films retain a Cu/Zn elemental composition ratio of 1.86 and exhibit primarily an α copper phase structure. Oxygen plasma pre-treatment for 1min before coating can significantly increase film adhesion such that the brass-coated fabric of Grade 5 or Grade 4-5 can ultimately be obtained under dry and wet rubbing tests, respectively. However, a deposition time of 1min suffices to provide effective antimicrobial properties for both Staphylococcus aureus and Escherichia coli. As a whole, the feasibility of using such advanced HIPIMS coating technique to develop durable antimicrobial textile was demonstrated.

  4. Modafinil increases reward salience in a slot machine game in low and high impulsivity pathological gamblers.

    PubMed

    Smart, Kelly; Desmond, Renée C; Poulos, Constantine X; Zack, Martin

    2013-10-01

    This study examined the effects of modafinil (200 mg) on slot machine betting profiles from a previous sample of low and high impulsivity (LI/HI) pathological gamblers (10/Group; Zack and Poulos, 2009). Hierarchical regression assessed the prospective relationship between Payoff and Bet Size on consecutive trials, along with moderating effects of Group, Cumulative Winnings (low/high) and Phase of game (early/late) under drug and placebo. Y intercepts for the simple regressions of Bet Size on Payoff indexed overall motivation to bet. Under placebo, both groups gauged their bets less closely to the preceding Payoff as trials continued when Winnings were low but not high. Under modafinil, both groups gauged their bets more closely to the preceding Payoff when Winnings were low but gauged their bets less closely to the previous Payoff when Winnings were high. The tendency to gauge bets closely to the previous Payoff coincided with a bias toward low overall Bet Size, and modafinil accentuated this relationship, in LI but not HI subjects. Results suggest that modafinil increases the salience of environmental rewards, leading to more tightly calibrated responses to individual rewards when resources are low, but progressively loosens reward-response calibration when resources are high. Increased relative impact of phasic vs. tonic dopamine signals may account for patterns seen at low vs. high Winnings, respectively, under the drug. Clinically, modafinil may deter pathological gamblers from chasing losses but also encourage them to continue betting rather than quit while they are ahead. Whether low-dose modafinil confers more uniform benefits deserves investigation.

  5. High precision micro-impulse measurements for micro-thrusters based on torsional pendulum and sympathetic resonance techniques.

    PubMed

    Zhang, Daixian; Wu, Jianjun; Zhang, Rui; Zhang, Hua; He, Zhen

    2013-12-01

    A sympathetic resonance theory is analyzed and applied in a newly developed torsional pendulum to measure the micro-impulse produced by a μN s-class ablative pulsed plasma thruster. According to theoretical analysis on the dynamical behaviors of a torsional pendulum, the resonance amplification effect of micro-signals is presented. In addition, a new micro-impulse measurement method based on sympathetic resonance theory is proposed as an improvement of the original single pulse measurement method. In contrast with the single pulse measurement method, the advantages of sympathetic resonance method are significant. First, because of the magnification of vibration signals due to resonance processes, measurement precision for the sympathetic resonance method becomes higher especially in reducing reading error. With an increase in peak number, the relative errors induced by readout of voltage signals decrease to approximately ±1.9% for the sympathetic resonance mode, whereas the relative error in single pulse mode is estimated as ±13.4%. Besides, by using the resonance amplification effect the sympathetic resonance method makes it possible to measure an extremely low-impulse beyond the resolution of a thrust stand without redesigning or purchasing a new one. Moreover, because of the simple operational principle and structure the sympathetic resonance method is much more convenient and inexpensive to be implemented than other high-precision methods. Finally, the sympathetic resonance measurement method can also be applied in other thrust stands to improve further the ability to measure the low-impulse bits.

  6. High precision micro-impulse measurements for micro-thrusters based on torsional pendulum and sympathetic resonance techniques

    NASA Astrophysics Data System (ADS)

    Zhang, Daixian; Wu, Jianjun; Zhang, Rui; Zhang, Hua; He, Zhen

    2013-12-01

    A sympathetic resonance theory is analyzed and applied in a newly developed torsional pendulum to measure the micro-impulse produced by a μN s-class ablative pulsed plasma thruster. According to theoretical analysis on the dynamical behaviors of a torsional pendulum, the resonance amplification effect of micro-signals is presented. In addition, a new micro-impulse measurement method based on sympathetic resonance theory is proposed as an improvement of the original single pulse measurement method. In contrast with the single pulse measurement method, the advantages of sympathetic resonance method are significant. First, because of the magnification of vibration signals due to resonance processes, measurement precision for the sympathetic resonance method becomes higher especially in reducing reading error. With an increase in peak number, the relative errors induced by readout of voltage signals decrease to approximately ±1.9% for the sympathetic resonance mode, whereas the relative error in single pulse mode is estimated as ±13.4%. Besides, by using the resonance amplification effect the sympathetic resonance method makes it possible to measure an extremely low-impulse beyond the resolution of a thrust stand without redesigning or purchasing a new one. Moreover, because of the simple operational principle and structure the sympathetic resonance method is much more convenient and inexpensive to be implemented than other high-precision methods. Finally, the sympathetic resonance measurement method can also be applied in other thrust stands to improve further the ability to measure the low-impulse bits.

  7. Localized traveling ionization zones and their importance for the high power impulse magnetron sputtering process

    NASA Astrophysics Data System (ADS)

    Maszl, Christian

    2016-09-01

    High power impulse magnetron sputtering (HiPIMS) is a technique to deposit thin films with superior quality. A high ionization degree up to 90% and the natural occurence of high energetic metal ions are the reason why HiPIMS exceeds direct current magnetron sputtering in terms of coating quality. On the other hand HiPIMS suffers from a reduced efficiency, especially if metal films are produced. Therefore, a lot of research is done by experimentalists and theoreticians to clarify the transport mechanisms from target to substrate and to identify the energy source of the energetic metal ions. Magnetron plasmas are prone to a wide range of wave phenomena and instabilities. Especially, during HiPIMS at elevated power/current densities, symmetry breaks and self-organization in the plasma torus are observed. In this scenario localized travelling ionization zones with certain quasi-mode numbers are present which are commonly referred to as spokes. Because of their high rotation speed compared to typical process times of minutes their importance for thin film deposition was underestimated at first. Recent investigations show that spokes have a strong impact on particle transport, are probably the source of the high energetic metal ions and are therefore the essence of HiPIMS plasmas. In this contribution we will describe the current understanding of spokes, discuss implications for thin film synthesis and highlight open questions. This project is supported by the DFG (German Science Foundation) within the framework of the Coordinated Research Center SFB-TR 87 and the Research Department ``Plasmas with Complex Interactions'' at Ruhr-University Bochum.

  8. Impulse Pump

    DTIC Science & Technology

    2016-06-17

    APPLICATIONS [0002] None. BACKGROUND OF THE INVENTION (1) Field of the Invention [0003] The present invention relates to an impulse pump for generating...impulse pump 15. The sleeve bearings 98 are affixed to the head block 90 to ease axial motion while the plunger 72 is under torsional loads. [0041

  9. Investigation of ionized metal flux in enhanced high power impulse magnetron sputtering discharges

    SciTech Connect

    Stranak, Vitezslav; Hubicka, Zdenek; Cada, Martin; Drache, Steffen; Hippler, Rainer; Tichy, Milan

    2014-04-21

    The metal ionized flux fraction and production of double charged metal ions Me{sup 2+} of different materials (Al, Cu, Fe, Ti) by High Power Impulse Magnetron Sputtering (HiPIMS) operated with and without a pre-ionization assistance is compared in the paper. The Electron Cyclotron Wave Resonance (ECWR) discharge was employed as the pre-ionization agent providing a seed of charge in the idle time of HiPIMS pulses. A modified grid-free biased quartz crystal microbalance was used to estimate the metal ionized flux fraction ξ. The energy-resolved mass spectrometry served as a complementary method to distinguish particular ion contributions to the total ionized flux onto the substrate. The ratio between densities of doubly Me{sup 2+} and singly Me{sup +} charged metal ions was determined. It is shown that ECWR assistance enhances Me{sup 2+} production with respect of absorbed rf-power. The ECWR discharge also increases the metal ionized flux fraction of about 30% especially in the region of lower pressures. Further, the suppression of the gas rarefaction effect due to enhanced secondary electron emission of Me{sup 2+} was observed.

  10. The behaviour of arcs in carbon mixed-mode high-power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Tucker, M. D.; Putman, K. J.; Ganesan, R.; Lattemann, M.; Stueber, M.; Ulrich, S.; Bilek, M. M. M.; McKenzie, D. R.; Marks, N. A.

    2017-04-01

    Mixed-mode deposition of carbon is an extension of high-power impulse magnetron sputtering in which a short-lived arc is deliberately allowed to ignite on the target surface to increase the ionised fraction of carbon in the deposition flux. Here we investigate the ignition and evolution of these arcs and examine their behaviour for different conditions of argon pressure, power supply voltage, and current. We find that mixed-mode deposition is sensitive to the condition of the target surface, and changing the operating parameters causes changes in the target surface condition which themselves affect the discharge in a process of negative feedback. Initially the arcs are evenly distributed on the target racetrack, but after a long period of operation the mode of erosion changes and arcs become localised in a small region, resulting in a pronounced nodular structure. We also quantify macroparticle generation and observe a power-law size distribution typical of arc discharges. Fewer particles are generated for operation at lower Ar pressure when the arc spot velocity is higher.

  11. Distance-dependent plasma composition and ion energy in high power impulse magnetron sputtering

    SciTech Connect

    Ehiasarian, Arutiun P; Andersson, Joakim; Anders, André

    2010-04-18

    The plasma composition of high power impulse magnetron sputtering (HIPIMS) has been studied for titanium and chromium targets using a combined energy analyser and quadrupole mass spectrometer. Measurements were done at distances from 50 to 300 mm from the sputtering target. Ti and Cr are similar in atomic mass but have significantly different sputter yields, which gives interesting clues on the effect of the target on plasma generation and transport of atoms. The Ti and Cr HIPIMS plasmas operated at a peak target current density of ~;;0.5 A cm-2. The measurements of the argon and metal ion content as well as the ion energy distribution functions showed that (1) singly and doubly charged ions were found for argon as well as for the target metal, (2) the majority of ions were singly charged argon for both metals at all distances investigated, (3) the Cr ion density was maintained to distances further from the target than Ti. Gas rarefaction was identified as a main factor promoting transport of metal ions, with the stronger effect observed for Cr, the material with higher sputter yield. Cr ions were found to displace a significant portion of the gas ions, whereas this was less evident in the Ti case. The observations indicate that the presence of metal vapour promotes charge exchange and reduces the electron temperature and thereby practically prevents the production of Ar2+ ions near the target. The content of higher charge states of metal ions depends on the probability of charge exchange with argon.

  12. Study of cobalt mononitride thin films prepared using DC and high power impulse magnetron sputtering

    SciTech Connect

    Gupta, Rachana; Pandey, Nidhi; Behera, Layanta; Gupta, Mukul

    2016-05-23

    In this work we studied cobalt mononitride (CoN) thin films deposited using dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS). A Co target was sputtered using pure N{sub 2} gas alone as the sputtering medium. Obtained long-range structural ordering was studies using x-ray diffraction (XRD), short-range structure using Co L{sub 2,3} and N K absorption edges using soft x-ray absorption spectroscopy (XAS) and the surface morphology using atomic force microscopy (AFM). It was found that HiPIMS deposited films have better long-range ordering, better stoichiometric ratio for mononitride composition and smoother texture as compared to dcMS deposited films. In addition, the thermal stability of HiPIMS deposited CoN film seems to be better. On the basis of different type of plasma conditions generated in HiPIMS and dcMS process, obtained results are presented and discussed.

  13. Impulsive stimulated scattering on metal and semiconductor interfaces under high pressure

    NASA Astrophysics Data System (ADS)

    Chronister, Eric; Baer, Bruce; Yamaguchi, Masashi

    2005-03-01

    Impulsive stimulated scattering (ISS) is used to measure the orientation dependence of surface acoustic wave velocities on crystalline metal and semiconductor surfaces. ISS coherently drives surface acoustic modes yielding a relatively large scattering efficiency [1]. ISS data is obtained continuously from the Rayleigh surface wave (RSW) branch through the pseudo RSW branch, which is typically not possible with classical Brillouin scattering. The ISS technique is found to be a robust non-contact method of probing the surface acoustic properties of metal and semiconductor crystalline interfaces. Orientationally resolved acoustic velocity data on crystal surfaces can be used to determine the bulk elastic constants of the material and ISS results were also found to be more robust than Brillouin scattering with respect to surface quality. At high pressure, the solid surface is in contact with a pressure-mediating fluid (nitrogen in this case), and the liquid-solid interface supports the propagation of a Sholte surface mode in addition to the generalized Rayliegh wave, both of which are resolved in the ISS power spectrum. 1] Rogers, Maznev, Banet, Nelson, Annu.Rev.Mater.Sci.30, 117, 2000.

  14. Digital high-pass filter deconvolution by means of an infinite impulse response filter

    NASA Astrophysics Data System (ADS)

    Födisch, P.; Wohsmann, J.; Lange, B.; Schönherr, J.; Enghardt, W.; Kaever, P.

    2016-09-01

    In the application of semiconductor detectors, the charge-sensitive amplifier is widely used in front-end electronics. The output signal is shaped by a typical exponential decay. Depending on the feedback network, this type of front-end electronics suffers from the ballistic deficit problem, or an increased rate of pulse pile-ups. Moreover, spectroscopy applications require a correction of the pulse-height, while a shortened pulse-width is desirable for high-throughput applications. For both objectives, digital deconvolution of the exponential decay is convenient. With a general method and the signals of our custom charge-sensitive amplifier for cadmium zinc telluride detectors, we show how the transfer function of an amplifier is adapted to an infinite impulse response (IIR) filter. This paper investigates different design methods for an IIR filter in the discrete-time domain and verifies the obtained filter coefficients with respect to the equivalent continuous-time frequency response. Finally, the exponential decay is shaped to a step-like output signal that is exploited by a forward-looking pulse processing.

  15. Subtypes of trait impulsivity differentially correlate with neural responses to food choices.

    PubMed

    van der Laan, Laura N; Barendse, Marjolein E A; Viergever, Max A; Smeets, Paul A M

    2016-01-01

    Impulsivity is a personality trait that is linked to unhealthy eating and overweight. A few studies assessed how impulsivity relates to neural responses to anticipating and tasting food, but it is unknown how impulsivity relates to neural responses during food choice. Although impulsivity is a multi-faceted construct, it is unknown whether impulsivity subtypes have different underlying neural mechanisms. We investigated how impulsivity correlates with brain responses during food choice and in how far different impulsivity subtypes modulate brain responses during food choice differently. Twenty weight-concerned females performed an fMRI task in which they indicated for high and low energy snacks whether or not they wanted to eat them. Impulsivity subtypes were measured by the monetary delay discounting task and the Barratt Impulsiveness Scale (total BIS-11 and subscales). Only temporal subtypes of impulsivity, namely delay discounting and the BIS-11 non-planning subscale, modulated responses to food choice; both measures correlated positively with striatum activation during high versus low energy choices. However, only delay discounting predicted high energy choices, whereas BIS-11 non-planning independently related to a striatum region that reflects subjective stimulus value. To conclude, the brain mechanisms underlying subtypes of impulsivity have a common ground but differ in specific aspects of food-related decision-making. The findings advance our understanding of the neural correlates of different impulsivity subtypes in the food domain. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Impulsivity (delay discounting) for food and cocaine in male and female rats selectively bred for high and low saccharin intake

    PubMed Central

    Nelson, Sarah E.; Anderson, Marissa M.; Morgan, Andrew D.; Carroll, Marilyn E.

    2009-01-01

    Previous research in rats indicates that delay discounting for food, a model of impulsivity, predicted the rate of acquisition of cocaine self-administration. In other studies, rats bred for high saccharin intake (HiS) acquired cocaine self-administration at higher rates than those with low saccharin intake (LoS), and female (F) rats acquired cocaine self-administration more rapidly than males (M). The purpose of this study was to examine a possible connection between impulsivity, saccharin intake, and sex by comparing M and F rats from the HiS and LoS selectively bred lines on measures of impulsivity; i.e., their rate of delay discounting for food or i.v. cocaine infusions. The adjusting delay procedure allowed rats access to 2 response levers, and a pellet dispenser or an i.v. drug infusion pump. In 4 groups (HiS M, HiS F, LoS M, LoS F) responses under a fixed-ratio (FR) 1 schedule on one lever resulted in one 45 mg pellet immediately, and responses on the other lever resulted in 3 or 6 pellets after a delay. Four additional groups received either a small cocaine (0.2, 0.4, or 0.8 mg/kg) infusion immediately or a delayed larger infusion (3 × the amount of the small infusions). The delay to the larger reinforcer began at 6 sec and increased or decreased by 1 s following responses on the delay or immediate levers, respectively. A mean adjusted delay (MAD) was calculated over 30 choice trials during each daily 3-hr session, and it was used as a quantitative measure of impulsivity. In groups maintained by food, HiS rats were more impulsive (lower MADs) than LoS rats, and LoS females were more impulsive than LoS males. There were no phenotype or sex differences in delay discounting for cocaine. Understanding the relationship between impulsivity and other predictors of drug abuse (e.g., sex, saccharin intake) is important in developing prevention and treatment strategies. PMID:17498785

  17. Tutorial: Reactive high power impulse magnetron sputtering (R-HiPIMS)

    NASA Astrophysics Data System (ADS)

    Anders, André

    2017-05-01

    High Power Impulse Magnetron Sputtering (HiPIMS) is a coating technology that combines magnetron sputtering with pulsed power concepts. By applying power in pulses of high amplitude and a relatively low duty cycle, large fractions of sputtered atoms and near-target gases are ionized. In contrast to conventional magnetron sputtering, HiPIMS is characterized by self-sputtering or repeated gas recycling for high and low sputter yield materials, respectively, and both for most intermediate materials. The dense plasma in front of the target has the dual function of sustaining the discharge and providing plasma-assistance to film growth, affecting the microstructure of growing films. Many technologically interesting thin films are compound films, which are composed of one or more metals and a reactive gas, most often oxygen or nitrogen. When reactive gas is added, non-trivial consequences arise for the system because the target may become "poisoned," i.e., a compound layer forms on the target surface affecting the sputtering yield and the yield of secondary electron emission and thereby all other parameters. It is emphasized that the target state depends not only on the reactive gas' partial pressure (balanced via gas flow and pumping) but also on the ion flux to the target, which can be controlled by pulse parameters. This is a critical technological opportunity for reactive HiPIMS (R-HiPIMS). The scope of this tutorial is focused on plasma processes and mechanisms of operation and only briefly touches upon film properties. It introduces R-HiPIMS in a systematic, step-by-step approach by covering sputtering, magnetron sputtering, reactive magnetron sputtering, pulsed reactive magnetron sputtering, HiPIMS, and finally R-HiPIMS. The tutorial is concluded by considering variations of R-HiPIMS known as modulated pulsed power magnetron sputtering and deep-oscillation magnetron sputtering and combinations of R-HiPIMS with superimposed dc magnetron sputtering.

  18. Neural correlates of high-risk behavior tendencies and impulsivity in an emotional Go/NoGo fMRI task

    PubMed Central

    Brown, Matthew R. G.; Benoit, James R. A.; Juhás, Michal; Lebel, R. M.; MacKay, Marnie; Dametto, Ericson; Silverstone, Peter H.; Dolcos, Florin; Dursun, Serdar M.; Greenshaw, Andrew J.

    2015-01-01

    Improved neuroscientific understanding of high-risk behaviors such as alcohol binging, drug use, and unsafe sex will lead to therapeutic advances for high-risk groups. High-risk behavior often occurs in an emotionally-charged context, and behavioral inhibition and emotion regulation play important roles in risk-related decision making. High impulsivity is an important potential contributor to high-risk behavior tendencies. We explored the relationships between high-risk behavior tendencies, impulsivity, and fMRI brain activations in an emotional Go/NoGo task. This task presented emotional distractor pictures (aversive vs. neutral) simultaneously with Go/NoGo stimuli (square vs. circle) that required a button press or withholding of the press, respectively. Participants' risk behavior tendencies were assessed with the Cognitive Appraisal of Risky Events (CARE) scale. The Barratt Impulsivity Scale 11 (BIS) was used to assess participant impulsivity. Individuals with higher CARE risk scores exhibited reduced activation related to response inhibition (NoGo−Go) in right orbital frontal cortex (OFC) and ventromedial prefrontal cortex. These regions did not show a significant relationship with impulsivity scores. Conversely, more impulsive individuals showed reduced emotion-related activity (aversive−neutral distractors) in dorsomedial prefrontal cortex, perigenual anterior cingulate cortex, and right posterior OFC. There were distinct neural correlates of high-risk behavior tendency and impulsivity in terms of brain activity in the emotional Go/NoGo task. This dissociation supports the conception of high-risk behavior tendency as a distinct construct from that of impulsivity. Our results suggest that treatment for high-risk behavior may be more effective with a nuanced approach that does not conflate high impulsivity necessarily with high-risk behavior tendencies. PMID:25805975

  19. A fully enclosed, compact standard lightning impulse generator for testing ultra-high-voltage-class gas-insulated switchgears with high capacitance.

    PubMed

    Wen, Tao; Zhang, Qiaogen; Zhang, Lingli; Zhao, Junping; Liu, Xuandong; Li, Xiaoang; Guo, Can; You, Haoyang; Chen, Weijiang; Yin, Yu; Shi, Weidong

    2016-03-01

    At present, conducting standard lightning impulse (LI) tests in the field for gas-insulated switchgear (GIS) equipment is difficult because of the high capacitance of the test equipment and large circuit inductance of traditional impulse devices, which leads to a wavefront time T(f) ≥ 2.5 μs. A novel fully enclosed, compact standard LI generator for testing ultra-high-voltage-class GIS equipment with high capacitance is presented to solve the problem of T(f) exceeding the standard during LI voltage tests for actual large-sized equipment. The impulse generator is installed in a metal vessel filled with SF6 or SF6/N2 gas mixture at a pressure of 0.3-0.5 MPa, providing a more compact structure and a lower series inductance. A newly developed conical voltage sensor is used to accurately measure the output voltage waveform. Two test modes (via bushing docking and direct docking) for the GIS test based on the impulse generator are introduced. Calculation results show that the impulse generator can generate an LI test waveform following the present IEC standard for the test of equipment with capacitance >10,000 pF.

  20. A fully enclosed, compact standard lightning impulse generator for testing ultra-high-voltage-class gas-insulated switchgears with high capacitance

    NASA Astrophysics Data System (ADS)

    Wen, Tao; Zhang, Qiaogen; Zhang, Lingli; Zhao, Junping; Liu, Xuandong; Li, Xiaoang; Guo, Can; You, Haoyang; Chen, Weijiang; Yin, Yu; Shi, Weidong

    2016-03-01

    At present, conducting standard lightning impulse (LI) tests in the field for gas-insulated switchgear (GIS) equipment is difficult because of the high capacitance of the test equipment and large circuit inductance of traditional impulse devices, which leads to a wavefront time Tf ≥ 2.5 μs. A novel fully enclosed, compact standard LI generator for testing ultra-high-voltage-class GIS equipment with high capacitance is presented to solve the problem of Tf exceeding the standard during LI voltage tests for actual large-sized equipment. The impulse generator is installed in a metal vessel filled with SF6 or SF6/N2 gas mixture at a pressure of 0.3-0.5 MPa, providing a more compact structure and a lower series inductance. A newly developed conical voltage sensor is used to accurately measure the output voltage waveform. Two test modes (via bushing docking and direct docking) for the GIS test based on the impulse generator are introduced. Calculation results show that the impulse generator can generate an LI test waveform following the present IEC standard for the test of equipment with capacitance >10 000 pF.

  1. Enhancement of bioactivity on medical polymer surface using high power impulse magnetron sputtered titanium dioxide film.

    PubMed

    Yang, Yi-Ju; Tsou, Hsi-Kai; Chen, Ying-Hung; Chung, Chi-Jen; He, Ju-Liang

    2015-12-01

    This study utilizes a novel technique, high power impulse magnetron sputtering (HIPIMS), which provides a higher ionization rate and ion bombardment energy than direct current magnetron sputtering (DCMS), to deposit high osteoblast compatible titanium dioxide (TiO2) coatings with anatase (A-TiO2) and rutile (R-TiO2) phases onto the biomedical polyetheretherketone (PEEK) polymer substrates at low temperature. The adhesions of TiO2 coatings that were fabricated using HIPIMS and DCMS were compared. The in vitro biocompatibility of these coatings was confirmed. The results reveal that HIPIMS can be used to prepare crystallinic columnar A-TiO2 and R-TiO2 coatings on PEEK substrate if the ratio of oxygen to argon is properly controlled. According to a tape adhesion test, the HIPIMS-TiO2 coatings had an adhesion grade of 5B even after they were immersed in simulated body fluid (SBF) environments for 28days. Scratch tests proved that HIPIMS-TiO2 coatings undergo cohesive failure. These results demonstrate that the adhesive force between HIPIMS-TiO2 coating/PEEK is stronger than that between DCMS-TiO2 coating/PEEK. After a long period (28days) of immersion in SBF, a bone-like crystallinic hydroxyapatite layer with a corresponding Ca/P stoichiometry was formed on both HIPIMS-TiO2. The osteoblast compatibility of HIPIMS-TiO2 exceeded that of the bare PEEK substrate. It is also noticeable that the R-TiO2 performed better in vitro than the A-TiO2 due to the formation of many negatively charged hydroxyl groups (-OH(-)) groups on R-TiO2 (110) surface. In summary, the HIPIMS-TiO2 coatings satisfied the requirements for osseointegration, suggesting the possibility of using HIPIMS to modify the PEEK surface with TiO2 for spinal implants.

  2. Investigation of plasma spokes in reactive high power impulse magnetron sputtering discharge

    NASA Astrophysics Data System (ADS)

    Hecimovic, A.; Corbella, C.; Maszl, C.; Breilmann, W.; von Keudell, A.

    2017-05-01

    Spokes, localised ionisation zones, are commonly observed in magnetron sputtering plasmas, appearing either with a triangular shape or with a diffuse shape, exhibiting self-organisation patterns. In this paper, we investigate the spoke properties (shape and emission) in a high power impulse magnetron sputtering (HiPIMS) discharge when reactive gas (N2 or O2) is added to the Ar gas, for three target materials; Al, Cr, and Ti. Peak discharge current and total pressure were kept constant, and the discharge voltage and mass flow ratios of Ar and the reactive gas were adjusted. The variation of the discharge voltage is used as an indication of a change of the secondary electron yield. The optical emission spectroscopy data demonstrate that by addition of reactive gas, the HiPIMS plasma exhibits a transition from a metal dominated plasma to the plasma dominated by Ar ions and, at high reactive gas partial pressures, to the plasma dominated by reactive gas ions. For all investigated materials, the spoke shape changed to the diffuse spoke shape in the poisoned mode. The change from the metal to the reactive gas dominated plasma and increase in the secondary electron production observed as the decrease of the discharge voltage corroborate our model of the spoke, where the diffuse spoke appears when the plasma is dominated by species capable of generating secondary electrons from the target. Behaviour of the discharge voltage and maximum plasma emission is strongly dependant on the target/reactive gas combination and does not fully match the behaviour observed in DC magnetron sputtering.

  3. Specific Dimensions of Impulsivity Are Differentially Associated with Daily and Non-Daily Cigarette Smoking in Young Adults

    PubMed Central

    Lee, Dustin C.; Peters, Jessica R.; Adams, Zachary W.; Milich, Richard; Lynam, Donald R.

    2015-01-01

    Young adults are at risk for initiation of tobacco use and progression to tobacco dependence. Not every person who smokes cigarettes becomes tobacco dependent, however, and non-daily smoking is becoming more prevalent among those who use tobacco. It is likely that individual differences in psychosocial and behavioral factors influence risk for engaging in non-daily and daily cigarette smoking. The objective of this study was to investigate the associations between impulsivity and smoking status in young adults who vary in frequency of cigarette smoking. Young adult first-year college students between the ages of 18-24 (512) were classified to one of three groups: non-smokers, non-daily smokers, or daily smokers, and impulsivity was assessed using the UPPS-P(Negative and Positive Urgency, lack of Premeditation, lack of Perseverance, Sensation Seeking). When all impulsivity dimensions were used simultaneously to predict smoking status, negative urgency predicted increased risk of membership in the daily smoking group and lack of premeditation predicted increased risk of membership in the non-daily smoking group. These results suggest that dimensions of impulsivity may contribute differentially to forms of smoking behavior in young adults. PMID:25827335

  4. Nonsputtering impulse magnetron discharge

    SciTech Connect

    Khodachenko, G. V.; Mozgrin, D. V.; Fetisov, I. K.; Stepanova, T. V.

    2012-01-15

    Experiments with quasi-steady high-current discharges in crossed E Multiplication-Sign B fields in various gases (Ar, N{sub 2}, H{sub 2}, and SF{sub 6}) and gas mixtures (Ar/SF{sub 6} and Ar/O{sub 2}) at pressures from 10{sup -3} to 5 Torr in discharge systems with different configurations of electric and magnetic fields revealed a specific type of stable low-voltage discharge that does not transform into an arc. This type of discharge came to be known as a high-current diffuse discharge and, later, a nonsputtering impulse magnetron discharge. This paper presents results from experimental studies of the plasma parameters (the electron temperature, the plasma density, and the temperature of ions and atoms of the plasma-forming gas) of a high-current low-pressure diffuse discharge in crossed E Multiplication-Sign B fields.

  5. Antioxidant loading reduces oxidative stress induced by high-energy impulse noise (blast) exposure.

    PubMed

    Elsayed, N M; Armstrong, K L; William, M T; Cooper, M F

    2000-11-30

    Detonation of explosives, firing of large caliber weapons and occupational explosions, professional or accidental, produce high-energy impulse noise (blast) waves characterized by a rapid rise in atmospheric pressure (overpressure) followed by gradual decay to ambient level. Exposure to blast waves causes injury, predominantly to the hollow organs such as ears and lungs. We have previously reported that blast exposure can induce free radical-mediated oxidative stress in the lung characterized by antioxidant depletion, lipid peroxidation, and hemoglobin (Hb) oxidation. In this study, we examined whether pre-loading, adequately fed rats, with pharmacological doses of antioxidants would reduce the response to blast. Sprague-Dawley rats weighing 300-350 g were loaded with either 800 IU vitamin E (VE), 1000 mg vitamin C (VC) or 25 mg lipoic acid (LA) for 3 consecutive days by gavage before exposure to blast. Both VE, and LA were dissolved in 2 ml corn oil, but VC in 2 ml water. After the 3-day antioxidant loading, the rats were divided into six groups (five rats per group), deeply anesthetized with sodium pentobarbital (60 mg/kg body weight), then exposed to a low-level blast (62+/-2 kPa peak pressure and 5 ms duration). A matched number of groups were sham exposed and served as controls. One hour after exposure, all rats were euthanized then blood, and lung tissue was analyzed. We found that antioxidant loading resulted in restored Hb oxygenation, and reduced lipid peroxidation. Lung tissue VE content was elevated after loading but VC did not change possibly due to their different bioavailability and saturation kinetics. These observations, suggest that brief antioxidant loading with pharmacological doses can reduce blast-induced oxidative stress, and may have occupational and clinical implications.

  6. High-frequency vibration energy harvesting from impulsive excitation utilizing intentional dynamic instability caused by strong nonlinearity

    NASA Astrophysics Data System (ADS)

    Remick, Kevin; Dane Quinn, D.; Michael McFarland, D.; Bergman, Lawrence; Vakakis, Alexander

    2016-05-01

    The authors investigate a vibration-based energy harvesting system utilizing essential (nonlinearizable) nonlinearities and electromagnetic coupling elements. The system consists of a grounded, weakly damped linear oscillator (primary system) subjected to a single impulsive load. This primary system is coupled to a lightweight, damped oscillating attachment (denoted as nonlinear energy sink, NES) via a neodymium magnet and an inductance coil, and a piano wire, which generates an essential geometric cubic stiffness nonlinearity. Under impulsive input, the transient damped dynamics of this system exhibit transient resonance captures (TRCs) causing intentional large-amplitude and high-frequency instabilities in the response of the NES. These TRCs result in strong energy transfer from the directly excited primary system to the light-weight attachment. The energy is harvested by the electromagnetic elements in the coupling and, in the present case, dissipated in a resistive element in the electrical circuit. The primary goal of this work is to numerically, analytically, and experimentally demonstrate the efficacy of employing this type of intentional high-frequency dynamic instability to achieve enhanced vibration energy harvesting under impulsive excitation.

  7. Impulse noise generator--design and operation.

    PubMed

    Brinkmann, H

    1991-01-01

    In the seventies PFANDER (Pfander, 1975) proposed a screening test with an impulse noise simulator to check the particular responsivity of soldiers on vulnerability of the inner ear concerning the impulse noise-induced hearing loss. According to a system developed at the University of Oldenburg (Germany) (Klug & Radek, 1987), we have constructed an impulse noise generator designed for our specific requirements that will be presented. The simulator consists of an electrical ignited impulse noise spark gap which is supplied by a 3.5 kV high voltage source. At a distance of 1.10 m from the center of the impulse noise spark gap a peak pressure level of 155 dB with a C-Duration (Pfander, 1975) of .2 msec and with the main energy in the frequency range from 1 kHz to 2 kHz was good reproducible. It would be preferable to shift the impulse noise spectrum to lower frequencies but experimental effort has failed so far.

  8. Effects of the combination of wheel running and atomoxetine on cue- and cocaine-primed reinstatement in rats selected for high or low impulsivity

    PubMed Central

    Zlebnik, Natalie E.; Carroll, Marilyn E.

    2014-01-01

    BACKGROUND Aerobic exercise and the attention-deficit/hyperactivity disorder medication, atomoxetine (ATO), are two monotherapies that have been shown to suppress reinstatement of cocaine seeking in an animal model of relapse. The present study investigated the effects of combining wheel running and ATO vs. each treatment alone on cocaine seeking precipitated by cocaine and cocaine-paired cues in rats with differing susceptibility to drug abuse (i.e., high vs. low impulsive). METHODS Rats were screened for high (HiI) or low impulsivity (LoI) based on their performance on a delay-discounting task and then trained to self-administer cocaine (0.4 mg/kg/inf) for 10 days. Following 14 days of extinction, both groups were tested for reinstatement of cocaine seeking precipitated by cocaine or cocaine-paired cues in the presence of concurrent running wheel access (W), pretreatment with ATO, or both (W+ATO). RESULTS HiI rats acquired cocaine self-administration more quickly than LoI rats. While both individual treatments and W+ATO significantly attenuated cue-induced cocaine seeking in HiI and LoI rats, only W+ATO was effective in reducing cocaine-induced reinstatement compared to vehicle treatment. There were dose-dependent and phenotype-specific effects of ATO with HiI rats responsive to the low but not high ATO dose. Floor effects of ATO and W on cue-induced reinstatement prevented the assessment of combined treatment effects. CONCLUSIONS These findings demonstrated greater attenuation of cue- vs. cocaine-induced reinstatement by ATO and W alone and recapitulate impulsivity phenotype differences in both acquisition of cocaine self-administration and receptivity to treatment. PMID:25258161

  9. Tutorial: Reactive high power impulse magnetron sputtering (R-HiPIMS)

    DOE PAGES

    Anders, André

    2017-03-21

    High Power Impulse Magnetron Sputtering (HiPIMS) is a coating technology that combines magnetron sputtering with pulsed power concepts. Furthermore, by applying power in pulses of high amplitude and a relatively low duty cycle, large fractions of sputtered atoms and near-target gases are ionized. In contrast to conventional magnetron sputtering, HiPIMS is characterized by self-sputtering or repeated gas recycling for high and low sputter yield materials, respectively, and both for most intermediate materials. The dense plasma in front of the target has the dual function of sustaining the discharge and providing plasma-assistance to film growth, affecting the microstructure of growing films.more » Many technologically interesting thin films are compound films, which are composed of one or more metals and a reactive gas, most often oxygen or nitrogen. When reactive gas is added, non-trivial consequences arise for the system because the target may become “poisoned,” i.e., a compound layer forms on the target surface affecting the sputtering yield and the yield of secondary electron emission and thereby all other parameters. It is emphasized that the target state depends not only on the reactive gas' partial pressure (balanced via gas flow and pumping) but also on the ion flux to the target, which can be controlled by pulse parameters. This is a critical technological opportunity for reactive HiPIMS (R-HiPIMS). The scope of this tutorial is focused on plasma processes and mechanisms of operation and only briefly touches upon film properties. It introduces R-HiPIMS in a systematic, step-by-step approach by covering sputtering, magnetron sputtering, reactive magnetron sputtering, pulsed reactive magnetron sputtering, HiPIMS, and finally R-HiPIMS. The tutorial is concluded by considering variations of R-HiPIMS known as modulated pulsed power magnetron sputtering and deep-oscillation magnetron sputtering and combinations of R-HiPIMS with superimposed dc magnetron

  10. Another Look at Impulsivity: A Meta- Analytic Review Comparing Specific Dispositions to Rash Action in their Relationship to Bulimic Symptoms

    PubMed Central

    Fischer, Sarah; Smith, Gregory T.; Cyders, Melissa A.

    2008-01-01

    Recent advances in personality theory indicate that there are distinct constructs that dispose individuals to rash action and risky behavior, as opposed to one broad trait of impulsivity. Two are emotion based, two represent deficits in conscientiousness, and one is sensation seeking. Previous studies of impulsivity and its relationship to bulimia nervosa have yielded mixed findings. The authors applied this advance in personality theory to the study of bulimia nervosa (BN) to test the hypothesis that the emotion-based disposition of negative urgency (the tendency to act rashly when distressed) relates most strongly to BN symptoms. A meta analysis of 50 articles indicated the following. Negative urgency had by far the largest effect size (weighted r = .38), followed by sensation seeking (weighted r = .16); lack of planning (weighted r = .16) and lack of persistence (weighted r = .08). Methodological moderators of the effect of distinct traits on BN symptoms were the use of scales that precisely measured one construct as opposed to general impulsivity scales that measured several constructs, clinical vs. non-clinical samples, and whether or not the personality scale was translated from its original language or not. Negative urgency appears especially important for BN; more broadly, researchers should consider the role of emotion-based dispositions to rash acts in their risk theories. PMID:18848741

  11. The diagnosis value of acoustic radiation force impulse (ARFI) elastography for thyroid malignancy without highly suspicious features on conventional ultrasound

    PubMed Central

    Liu, Bo-Ji; Lu, Feng; Xu, Hui-Xiong; Guo, Le-Hang; Li, Dan-Dan; Bo, Xiao-Wan; Li, Xiao-Long; Zhang, Yi-Feng; Xu, Jun-Mei; Xu, Xiao-Hong; Qu, Shen

    2015-01-01

    Objective: The aim of this study was to evaluate the potential diagnostic performance of acoustic radiation force impulse (ARFI) elastography in identifying malignancy in nodules that do not appear highly suspicious on conventional ultrasound (US). Methods: 330 pathologically confirmed thyroid nodules (40 malignant and 290 benign; mean size, 22.0±11.6 mm) not suspicious of malignancy on conventional US in 330 patients (mean age 52.8±11.7 years) underwent ARFI elastography before surgery. ARFI elastography included qualitative ARFI-induced strain elastography (SE) and quantitative point shear wave elastography (p-SWE). ARFI-induced SE image was assessed by SE score, while p-SWE was denoted with shear wave velocity (SWV, m/s). The diagnostic performance of four criteria sets was evaluated: criteria set 1 (ARFI-induced SE), criteria set 2 (p-SWE), criteria set 3 (either set 1 or 2), criteria set 4 (both set 1 and 2). Receiver operating characteristic curve (ROC) analyses were performed to assess the diagnostic performance. Results: SE score ≥4 was more frequently found in malignant nodules (32/40) than in benign nodules (30/290, P<0.001). The mean SWV of malignant nodules (3.64±2.23 m/s) was significantly higher than that of benign nodules (2.02±0.69 m/s) (P<0.001). ARFI-induced SE (set 1) had a sensitivity of 80.0% (32/40) and a specificity of 89.7% (260/290) with a cut-off point of SE score ≥4; p-SWE (set 2) had a sensitivity of 80.0% (32/40) and a specificity of 57.9% (168/290) with a cut-off point of SWV ≥2.15 m/s. When ARFI-induced SE and p-SWE were combined, set 3 had the highest sensitivity (92.5%, 37/40) while set 4 had the highest specificity (95.2%, 276/290). Conclusion: ARFI elastography can be used for differential diagnosis of malignant thyroid nodules without highly suspicious features on US. The combination of ARFI-induced SE and p-SWE leads to improved sensitivity and specificity. PMID:26629025

  12. Impulsivity and methamphetamine use.

    PubMed

    Semple, Shirley J; Zians, Jim; Grant, Igor; Patterson, Thomas L

    2005-09-01

    The purpose of this study was to explore the relationship between methamphetamine (meth) use and impulsivity in a sample of 385 HIV-negative heterosexually identified meth users. Participants who scored highest on a self-report measure of impulsivity were compared with those who scored lower in terms of background characteristics, meth use patterns, use of alcohol and other illicit drugs, sexual risk behavior, and psychiatric health variables. Methamphetamine users in the high impulsivity group were younger, less educated, used larger quantities of meth, were more likely to be binge users, had a larger number of sexual partners, engaged in more unprotected vaginal and oral sex, and scored higher on the Beck Depression Inventory as compared with those in the low impulsivity group. In a logistic regression analysis, Beck depression was the factor that best distinguished between meth users who scored high and those who scored low on impulsivity. Neurophysiological pathways that may underlie the relationship between impulsivity and meth use are discussed.

  13. High specific activity silicon-32

    DOEpatents

    Phillips, D.R.; Brzezinski, M.A.

    1996-06-11

    A process for preparation of silicon-32 is provided and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidation state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.

  14. High specific activity silicon-32

    DOEpatents

    Phillips, Dennis R.; Brzezinski, Mark A.

    1996-01-01

    A process for preparation of silicon-32 is provided and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution to from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidization state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.

  15. Cocaine-induced c-Fos expression in rats selectively bred for high or low saccharin intake and in rats selected for high or low impulsivity.

    PubMed

    Regier, Paul S; Carroll, Marilyn E; Meisel, Robert L

    2012-08-01

    Sweet preference and impulsivity are predictors of cocaine self-administration; however, no research has been conducted to investigate neuronal activation in key brain reward areas after first time exposure to cocaine in rats that differ in their propensity for cocaine-seeking and -taking behavior. In this study we used rats that had been selectively bred for high vs. low saccharin intake and rats selected for high vs. low impulsivity for food. The goal of this study was to investigate whether there are differences of c-Fos reactivity between high and low phenotypes and determine whether these differences are similar between the two animal models. A group of rats was bred for high or low saccharin intake. Another group of rats was selected as high or low impulsive based on performance in a delay-discounting task. Subsequently, rats were given an acute injection of cocaine or saline and then c-Fos expression was observed and analyzed in several brain regions. The low reward-seeking phenotypes showed higher cocaine-induced c-Fos expression in several of these regions. Low saccharin preferring rats showed higher cocaine-induced c-Fos expression in the nucleus accumbens shell, and low impulsive rats showed higher cocaine-induced c-Fos expression in the orbitofrontal cortex and cingulate gyrus 1 area. In addition, both low impulsive and low saccharin rats had higher cocaine-induced c-Fos in the dorsal medial and dorsal lateral caudate putamen. The results indicate that individual differences in neuronal reactivity exist prior to chronic exposure to drugs of abuse. Furthermore, similar differences between the two animal models may be indicative of a common mechanism underlying vulnerability to drugs of abuse. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Cocaine-induced c-Fos expression in rats selectively bred for high or low saccharin intake and in rats selected for high or low impulsivity

    PubMed Central

    Carroll, Marilyn E.; Meisel, Robert L.

    2013-01-01

    Sweet preference and impulsivity are predictors of cocaine self-administration; however no research has been conducted to investigate neuronal activation in key brain reward areas after first time exposure to cocaine in rats that differ in their propensity for cocaine-seeking and – taking behavior. In this study we used rats that that been selectively bred for high vs. low saccharin intake and rats selected for high vs. low impulsivity for food. The goal of this study was to investigate whether there are differences of c-Fos reactivity between high and low phenotypes and determine whether these differences are similar between the two animal models. A group of rats was bred for either high or low saccharin intake. Another group of rats was selected as high or low impulsive based on performance in a delay-discounting task. Subsequently, rats were given an acute injection of cocaine or saline and then c-Fos expression was observed and analyzed in several brain regions. The low reward-seeking phenotypes showed higher cocaine-induced c-Fos expression in several of these regions. Low saccharin preferring rats showed higher cocaine-induced c-Fos expression in the nucleus accumbens shell, and low impulsive rats showed higher cocaine-induced c-Fos expression in the orbitofrontal cortex and cingulate gyrus 1 area. In addition, both low impulsive and low saccharin rats had higher cocaine-induced c-Fos in the dorsal medial and dorsal lateral caudate putamen. The results indicate that individual differences in neuronal reactivity exist prior to chronic exposure to drugs of abuse. Furthermore, similar differences between the two animal models may be indicative of a common mechanism underlying vulnerability to drugs of abuse. PMID:22613730

  17. Impulse generation by detonation tubes

    NASA Astrophysics Data System (ADS)

    Cooper, Marcia Ann

    Impulse generation with gaseous detonation requires conversion of chemical energy into mechanical energy. This conversion process is well understood in rocket engines where the high pressure combustion products expand through a nozzle generating high velocity exhaust gases. The propulsion community is now focusing on advanced concepts that utilize non-traditional forms of combustion like detonation. Such a device is called a pulse detonation engine in which laboratory tests have proven that thrust can be achieved through continuous cyclic operation. Because of poor performance of straight detonation tubes compared to conventional propulsion systems and the success of using nozzles on rocket engines, the effect of nozzles on detonation tubes is being investigated. Although previous studies of detonation tube nozzles have suggested substantial benefits, up to now there has been no systematic investigations over a range of operating conditions and nozzle configurations. As a result, no models predicting the impulse when nozzles are used exist. This lack of data has severely limited the development and evaluation of models and simulations of nozzles on pulse detonation engines. The first experimental investigation measuring impulse by gaseous detonation in plain tubes and tubes with nozzles operating in varying environment pressures is presented. Converging, diverging, and converging-diverging nozzles were tested to determine the effect of divergence angle, nozzle length, and volumetric fill fraction on impulse. The largest increases in specific impulse, 72% at an environment pressure of 100 kPa and 43% at an environment pressure of 1.4 kPa, were measured with the largest diverging nozzle tested that had a 12° half angle and was 0.6 m long. Two regimes of nozzle operation that depend on the environment pressure are responsible for these increases and were first observed from these data. To augment this experimental investigation, all data in the literature regarding

  18. High-intensity drying processes: Impulse drying modeling of fluid flow and heat transfer in a crown compensated impulse drying press roll, The lubrication problem. Annual report

    SciTech Connect

    Orloff, D.I.; Hojjatie, B.; Bloom, F.

    1994-08-01

    Although evaporative drying is currently used to dry paper, research has showed that significant energy savings could be realized with the newer impulse drying technology in drying heavy weight grades of paper. This report analyzes the lubrication problem which arises in modeling impulse drying employing a crown compensated roll. The geometry for the associated steady flow problem is constructed and expressions are derived for the relevant velocity fields, mass flow rates, and normal and tangential forces acting on both the bottom surface of an internal hydrostatic shoe and the inside surface of the crown-compensated roll. Results from the analytical model agreed well with experimental data from Beloit Corp. for the small shoe/roll configuration. The model can be used to predict effect of design and physical parameters on the performance of the press roll (lubricant thickness, pressure distributions, mechanical power required to operate the roll, etc.) and to determine optimal performance under various operating conditions.

  19. Seismic Emissions from a Highly Impulsive M6.7 Solar Flare

    NASA Astrophysics Data System (ADS)

    Martínez-Oliveros, J. C.; Moradi, H.; Donea, A.-C.

    2008-09-01

    On 10 March 2001 the active region NOAA 9368 produced an unusually impulsive solar flare in close proximity to the solar limb. This flare has previously been studied in great detail, with observations classifying it as a type 1 white-light flare with a very hard spectrum in hard X-rays. The flare was also associated with a type II radio burst and coronal mass ejection. The flare emission characteristics appeared to closely correspond to previous instances of seismic emission from acoustically active flares. Using standard local helioseismic methods, we identified the seismic signatures produced by the flare that, to date, is the least energetic (in soft X-rays) of the flares known to have generated a detectable acoustic transient. Holographic analysis of the flare shows a compact acoustic source strongly correlated with the impulsive hard X-rays, visible continuum, and radio emission. Time distance diagrams of the seismic waves emanating from the flare region also show faint signatures, mainly in the eastern sector of the active region. The strong spatial coincidence between the seismic source and the impulsive visible continuum emission reinforces the theory that a substantial component of the seismic emission seen is a result of sudden heating of the low photosphere associated with the observed visible continuum emission. Furthermore, the low-altitude magnetic loop structure inferred from potential-field extrapolations in the flaring region suggests that there is a significant anti-correlation between the seismicity of a flare and the height of the magnetic loops that conduct the particle beams from the corona.

  20. Quenching electron runaway in positive high-voltage-impulse discharges in air by laser filaments.

    PubMed

    Eto, S; Zhidkov, A; Oishi, Y; Miki, M; Fujii, T

    2012-03-15

    Strong hard (ε>100 keV) x rays being observed from impulse atmospheric discharges with maximal voltages from U=0.5 to 0.9 MV just before the breakdown were completely stopped with the use of femtosecond-laser-filament plasma. Runaway electrons generating such x rays and being estimated to achieve their maximal energy, ε~U, near the positive electrode disappear if a laser filament plasma is ignited perpendicularly to the runaway near the positive electrode. A preheating mechanism for formation of the electron runaway in air is proposed.

  1. Self-sputtering runaway in high power impulse magnetron sputtering: The role of secondary electrons and multiply charged metal ions

    SciTech Connect

    Anders, Andre

    2008-05-19

    Self-sputtering runaway in high power impulse magnetron sputtering is closely related to the appearance of multiply charged ions. This conclusion is based on the properties of potential emission of secondary electrons and energy balance considerations. The effect is especially strong for materials whose sputtering yield is marginally greater than unity. The absolute deposition rate increases {approx}Q{sup 1/2}, whereas the rate normalized to the average power decreases {approx}Q{sup -1/2}, with Q being the mean ion charge state number.

  2. Photonic generation and wireless transmission of different pulse modulation formats for high-speed impulse radio ultrawideband over fiber systems

    NASA Astrophysics Data System (ADS)

    Xie, Shizhong; Chen, Hongwei; Chen, Minghua; Yang, Sigang; Li, Pengxiao

    2011-12-01

    Novel methods on photonic generation of different pulse modulation formats for impulse radio ultra-wideband (IR-UWB) over fiber application is overviewed. A flexible, high-speed and power-efficient photonic on-off keying and binary phase shift keying modulated IR-UWB over fiber communication system is proposed and demonstrated. IR-UWB transmission over 20km fiber and 0.25m wireless link without any compensation is presented. The transmission performance for both modulation formats is evaluated and compared by measuring eye diagrams and the electrical spectra.

  3. The Relationship between the UPPS-P Impulsivity Dimensions and Nonsuicidal Self-Injury Characteristics in Male and Female High-School Students

    PubMed Central

    2013-01-01

    The present study investigated the association between nonsuicidal self-injury characteristics, functions, and the UPPS-P impulsivity-related traits in high-school students using self-report questionnaires. More than 17% of the 613 students engaged in at least one type of NSSI behavior. Compared to male students, female students engaged more often in cutting and less in head banging. All NSSI behaviors were significantly related to Negative and Positive Urgency, that is, the tendency to act impulsive in the presence of negative/positive affect. Interactions between different UPPS-P impulsivity dimensions did not increase the percentage of explained variance in the different NSSI behaviors. Furthermore, severe cutting was negatively related to Lack of Premeditation. Different NSSI functions showed differential relationships with the five UPPS-P impulsivity dimensions. PMID:24236284

  4. The Relationship between the UPPS-P Impulsivity Dimensions and Nonsuicidal Self-Injury Characteristics in Male and Female High-School Students.

    PubMed

    Claes, Laurence; Muehlenkamp, Jennifer

    2013-01-01

    The present study investigated the association between nonsuicidal self-injury characteristics, functions, and the UPPS-P impulsivity-related traits in high-school students using self-report questionnaires. More than 17% of the 613 students engaged in at least one type of NSSI behavior. Compared to male students, female students engaged more often in cutting and less in head banging. All NSSI behaviors were significantly related to Negative and Positive Urgency, that is, the tendency to act impulsive in the presence of negative/positive affect. Interactions between different UPPS-P impulsivity dimensions did not increase the percentage of explained variance in the different NSSI behaviors. Furthermore, severe cutting was negatively related to Lack of Premeditation. Different NSSI functions showed differential relationships with the five UPPS-P impulsivity dimensions.

  5. High pressure, energy, and impulse loading of the wall in a 1-GJ Laboratory Microfusion Facility

    SciTech Connect

    Harrach, R.J.

    1989-07-24

    A proposed Laboratory Microfusion Facility (LMF) must be able to withstand repeated, low-repetition-rate fusion explosions at the 1-GJ (one-quarter ton) yield level. The energy release will occur at the center of a chamber only a few meters in radius, subjecting the interior or first wall to severe levels of temperature, pressure, and impulse. We show by theory and computation that the wall loading can be ameliorated by interposing a spherical shell of low-Z material between the fuel and the wall. This sacrificial shield converts the source energy components that are most damaging to the wall (soft x-rays and fast ions) to more benign plasma kinetic energy from the vaporized shield, and stretches the time duration over which this energy is delivered to the wall from nanoseconds to microseconds. Numerical calculations emphasize thin, volleyball-sized plastic shields, and much thicker ones of frozen nitrogen. Wall shielding criteria of small (or no) amount of surface ablation, low impulse and pressure loading, minimal shrapnel danger, small expense, and convenience in handling all favor the thin plastic shields. 7 refs., 4 figs.

  6. Impulsivity in the supermarket. Responses to calorie taxes and subsidies in healthy weight undergraduates.

    PubMed

    Giesen, Janneke C A H; Havermans, Remco C; Nederkoorn, Chantal; Jansen, Anita

    2012-02-01

    The present study investigated the effect of taxing high-energy dense products and subsidizing low-energy dense products on changes in calorie consumption. More specifically, we hypothesized that 'more impulsive' individuals were less influenced by such pricing strategies compared to 'less impulsive' individuals. Contrary to our hypothesis, results showed that 'more impulsive' individuals adjusted their calorie consumption with regard to price changes whereas 'less impulsive' participants were less influenced by price changes. Furthermore, taxing high-energy dense products was more successful in reducing calorie consumption than subsidizing low-energy dense products.

  7. Impulsivity and aggressive behavior in Roman high and low avoidance rats: baseline differences and adolescent social stress induced changes.

    PubMed

    Coppens, Caroline M; de Boer, Sietse F; Steimer, Thierry; Koolhaas, Jaap M

    2012-03-20

    Adverse and stressful experiences during adolescence are often of a social nature. The social defeat model in rats is used as an animal model for bullying in humans. Usually large individual differences in response to social defeat are found. The personality type that is mostly affected and the underlying mechanisms are unknown. We used male rats of the Roman selection lines to test whether social defeat (between postnatal days 45 and 57) followed by social isolation has a different impact in animals with divergent levels of emotional reactivity and coping style. The level of offensive aggression, impulsivity and performance during frustrating non-reward (extinction) were used as measures for the adult coping style of animals. Impulsivity was measured by performance on an unpredictable operant conditioning schedule (variable interval-15, VI-15) for food reinforcement. This study demonstrates that the adult, baseline level of impulsivity is higher in Roman high avoidance (RHA) rats. RHA rats showed a higher number of lever presses compared to Roman low avoidance (RLA) rats on a VI-15 schedule. The level of offensive aggression did not differ between the two lines. Surprisingly, a tendency towards more offensive aggression in RLA rats was found. Social stress during adolescence disturbed the normal development of adult personality, mostly in RHA rats. RHA rats that were defeated during adolescence reduced the number of lever presses on the VI-15 schedule of reinforcement and were more persistent during a session of frustrating non-reward. However, we did not find an effect of social defeat on performance during extinction. A tendency towards increased attack latencies after social defeat in adolescence was found. The time spent on offensive aggression was unaffected by social defeat.

  8. Impulsive and long duration high-energy gamma-ray emission from the very bright 2012 March 7 solar flares

    SciTech Connect

    Ajello, M.; Albert, A.; Allafort, A.; Caliandro, G. A.; Cameron, R. A.; Charles, E.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Buson, S.; Bellazzini, R.; Bregeon, J.; Bissaldi, E.; Bonamente, E.; Cecchi, C.; Brandt, T. J.; Brigida, M.; Bruel, P.; Caraveo, P. A. E-mail: vahep@stanford.edu; and others

    2014-07-01

    The Fermi Large Area Telescope (LAT) detected gamma-rays up to 4 GeV from two bright X-class solar flares on 2012 March 7, showing both an impulsive and temporally extended emission phases. The gamma-rays appear to originate from the same active region as the X-rays associated with these flares. The >100 MeV gamma-ray flux decreases monotonically during the first hour (impulsive phase) followed by a slower decrease for the next 20 hr. A power law with a high-energy exponential cutoff can adequately describe the photon spectrum. Assuming that the gamma rays result from the decay of pions produced by accelerated protons and ions with a power-law spectrum, we find that the index of that spectrum is ∼3, with minor variations during the impulsive phase. During the extended phase the photon spectrum softens monotonically, requiring the proton index varying from ∼4 to >5. The >30 MeV proton flux observed by the GOES satellites also shows a flux decrease and spectral softening, but with a harder spectrum (index ∼2-3). Based on these observations, we explore the relative merits of prompt or continuous acceleration scenarios, hadronic or leptonic emission processes, and acceleration at the solar corona or by the fast coronal mass ejections. We conclude that the most likely scenario is continuous acceleration of protons in the solar corona that penetrate the lower solar atmosphere and produce pions that decay into gamma rays. However, acceleration in the downstream of the shock cannot be definitely ruled out.

  9. Impulsive And Long Duration High-Energy Gamma-Ray Emission From The Very Bright 2012 March 7 Solar Flares

    SciTech Connect

    Ajello, M.

    2014-06-10

    The Fermi Large Area Telescope (LAT) observed two bright X-class solar ares on 2012 March 7, and detected gamma-rays up to 4 GeV. We detected gamma-rays both during the impulsive and temporally-extended emission phases, with emission above 100 MeV lasting for approximately 20 hours. Accurate localization of the gamma-ray production site(s) coincide with the solar active region from which X-ray emissions associated with these ares originated. Our analysis of the > 100 MeV gamma-ray emission shows a relatively rapid monotonic decrease in flux during the first hour of the impulsive phase, and a much slower, almost monotonic decrease in flux for the next 20 hours. The spectra can be adequately described by a power law with a high energy exponential cutoff, or as resulting from the decay of neutral pions produced by accelerated protons and ions with an isotropic power-law energy distribution. The required proton spectrum has a number index 3, with minor variations during the impulsive phase, while during the temporally extended phase the spectrum softens monotonically, starting with index 4. The > 30 MeV proton flux and spectra observed near the Earth by the GOES satellites also show a monotonic flux decrease and spectral softening during the extended phase, but with a harder spectrum, with index 3. Based on the Fermi-LAT and GOES observations of the flux and spectral evolution of these bright ares, we explore the relative merits of prompt and continuous acceleration scenarios, hadronic and leptonic emission processes, and acceleration at the solar corona by the fast Coronal Mass Ejections (CME) as explanations for the observations. We conclude that the most likely scenario is continuous acceleration of protons in the solar corona which penetrate the lower solar atmosphere and produce pions that decay into gamma-rays.

  10. Impulsive And Long Duration High-Energy Gamma-Ray Emission From The Very Bright 2012 March 7 Solar Flares

    DOE PAGES

    Ajello, M.

    2014-06-10

    The Fermi Large Area Telescope (LAT) observed two bright X-class solar ares on 2012 March 7, and detected gamma-rays up to 4 GeV. We detected gamma-rays both during the impulsive and temporally-extended emission phases, with emission above 100 MeV lasting for approximately 20 hours. Accurate localization of the gamma-ray production site(s) coincide with the solar active region from which X-ray emissions associated with these ares originated. Our analysis of the > 100 MeV gamma-ray emission shows a relatively rapid monotonic decrease in flux during the first hour of the impulsive phase, and a much slower, almost monotonic decrease in fluxmore » for the next 20 hours. The spectra can be adequately described by a power law with a high energy exponential cutoff, or as resulting from the decay of neutral pions produced by accelerated protons and ions with an isotropic power-law energy distribution. The required proton spectrum has a number index 3, with minor variations during the impulsive phase, while during the temporally extended phase the spectrum softens monotonically, starting with index 4. The > 30 MeV proton flux and spectra observed near the Earth by the GOES satellites also show a monotonic flux decrease and spectral softening during the extended phase, but with a harder spectrum, with index 3. Based on the Fermi-LAT and GOES observations of the flux and spectral evolution of these bright ares, we explore the relative merits of prompt and continuous acceleration scenarios, hadronic and leptonic emission processes, and acceleration at the solar corona by the fast Coronal Mass Ejections (CME) as explanations for the observations. We conclude that the most likely scenario is continuous acceleration of protons in the solar corona which penetrate the lower solar atmosphere and produce pions that decay into gamma-rays.« less

  11. Application of a Channel Design Method to High-Solidity Cascades and Tests of an Impulse Cascade with 90 Degrees of Turning

    NASA Technical Reports Server (NTRS)

    Stanitz, John D; Sheldrake, Leonard J

    1953-01-01

    A technique is developed for the application of a channel design method to the design of high-solidity cascades with prescribed velocity distributions as a function of arc length along the blade-element profile. The technique is applied to both incompressible and subsonic compressible, nonviscous, irrotational fluid motion. For compressible flow, the ratio of specific heats is assumed equal to -1.0. An impulse cascade with 90 degree turning was designed for incompressible flow and was tested at the design angle of attack over a range of downstream Mach number from 0.2 to coke flow. To achieve good efficiency, the cascade was designed for prescribed velocities and maximum blade loading according to limitations imposed by considerations of boundary-layer separation.

  12. Impulsivity is Associated with Uric Acid: Evidence from Humans and Mice

    PubMed Central

    Sutin, Angelina R.; Cutler, Roy G.; Camandola, Simonetta; Uda, Manuela; Feldman, Neil H.; Cucca, Francesco; Zonderman, Alan B.; Mattson, Mark P.; Ferrucci, Luigi; Schlessinger, David; Terracciano, Antonio

    2013-01-01

    Background The ability to control impulses varies greatly, and difficulty with impulse control can have severe consequences; in the extreme, it is the defining feature of many psychiatric disorders. Evidence from disparate lines of research suggests that uric acid is elevated in psychiatric disorders characterized by high impulsivity, such as ADHD and bipolar disorder. The present research tests the hypothesis that impulsivity is associated with higher uric acid in humans and mice. Methods Using two longitudinal, non-clinical community samples (total N=6883), we test whether there is an association between uric acid and normal variation in trait impulsivity measured with the Revised NEO Personality Inventory. We also examined the effect of uric acid on behavior by comparing wild-type mice (WT), which naturally have low levels of uric acid, to mice genetically modified (UOX) to accumulate high levels of uric acid. Results In both human samples, the emotional aspects of trait impulsivity, specifically Impulsiveness and Excitement-Seeking, were associated with higher levels of uric acid concurrently and when uric acid was measured 3–5 years later. Consistent with the human data, the UOX mice displayed significantly more exploratory and novelty-seeking behavior than the WT mice. Conclusion Higher uric acid was associated with impulsivity in both humans and mice. The identification of biological markers of impulsivity may lead to a better understanding of the physiological mechanisms involved in impulsivity, and may suggest potential targets for therapeutic intervention. PMID:23582268

  13. Baseline impulsive choice predicts the effects of nicotine and nicotine withdrawal on impulsivity in rats.

    PubMed

    Kayir, Hakan; Semenova, Svetlana; Markou, Athina

    2014-01-03

    Impulsive choice, a form of impulsivity, is associated with tobacco smoking in humans. Trait impulsivity may be a vulnerability factor for smoking, or smoking may lead to impulsive behaviors. We investigated the effects of 14-day nicotine exposure (6.32mg/kg/day base, subcutaneous minipumps) and spontaneous nicotine withdrawal on impulsive choice in low impulsive (LI) and high impulsive (HI) rats. Impulsive choice was measured in the delayed reward task in which rats choose between a small immediate reward and a large delayed reward. HI and LI rats were selected from the highest and lowest quartiles of the group before exposure to nicotine. In non-selected rats, nicotine or nicotine withdrawal had no effect on impulsive choice. In LI rats, chronic nicotine exposure decreased preference for the large reward with larger effects at longer delays, indicating increased impulsive choice. Impulsive choices for the smaller immediate rewards continued to increase during nicotine withdrawal in LI rats. In HI rats, nicotine exposure and nicotine withdrawal had no effect on impulsive choice, although there was a tendency for decreased preference for the large reward at short delays. These results indicate that nicotine- and nicotine withdrawal-induced increases in impulsive choice depend on trait impulsivity with more pronounced increases in impulsive choice in LI compared to HI subjects. Increased impulsivity during nicotine exposure may strengthen the addictive properties of nicotine and contribute to compulsive nicotine use.

  14. DEPOSITION OF NIOBIUM AND OTHER SUPERCONDUCTING MATERIALS WITH HIGH POWER IMPULSE MAGNETRON SPUTTERING: CONCEPT AND FIRST RESULTS

    SciTech Connect

    High Current Electronics Institute, Tomsk, Russia; Anders, Andre; Mendelsberg, Rueben J.; Lim, Sunnie; Mentink, Matthijs; Slack, Jonathan L.; Wallig, Joseph G.; Nollau, Alexander V.; Yushkov, Georgy Yu.

    2011-07-24

    Niobium coatings on copper cavities have been considered as a cost-efficient replacement of bulk niobium RF cavities, however, coatings made by magnetron sputtering have not quite lived up to high expectations due to Q-slope and other issues. High power impulse magnetron sputtering (HIPIMS) is a promising emerging coatings technology which combines magnetron sputtering with a pulsed power approach. The magnetron is turned into a metal plasma source by using very high peak power density of ~ 1 kW/cm{sup 2}. In this contribution, the cavity coatings concept with HIPIMS is explained. A system with two cylindrical, movable magnetrons was set up with custom magnetrons small enough to be inserted into 1.3 GHz cavities. Preliminary data on niobium HIPIMS plasma and the resulting coatings are presented. The HIPIMS approach has the potential to be extended to film systems beyond niobium, including other superconducting materials and/or multilayer systems.

  15. Turbulent-PSO-Based Fuzzy Image Filter With No-Reference Measures for High-Density Impulse Noise.

    PubMed

    Chou, Hsien-Hsin; Hsu, Ling-Yuan; Hu, Hwai-Tsu

    2013-02-01

    Digital images are often corrupted by impulsive noise during data acquisition, transmission, and processing. This paper presents a turbulent particle swarm optimization (PSO) (TPSO)-based fuzzy filtering (or TPFF for short) approach to remove impulse noise from highly corrupted images. The proposed fuzzy filter contains a parallel fuzzy inference mechanism, a fuzzy mean process, and a fuzzy composition process. To a certain extent, the TPFF is an improved and online version of those genetic-based algorithms which had attracted a number of works during the past years. As the PSO is renowned for its ability of achieving success rate and solution quality, the superiority of the TPFF is almost for sure. In particular, by using a no-reference Q metric, the TPSO learning is sufficient to optimize the parameters necessitated by the TPFF. Therefore, the proposed fuzzy filter can cope with practical situations where the assumption of the existence of the "ground-truth" reference does not hold. The experimental results confirm that the TPFF attains an excellent quality of restored images in terms of peak signal-to-noise ratio, mean square error, and mean absolute error even when the noise rate is above 0.5 and without the aid of noise-free images.

  16. [Impulsivity as an immediate factor between addictive disorders and Attention Deficit-Hyperactivity Disorder].

    PubMed

    Lazaratou, H; Palaiologou, A; Anagnostopoulos, D

    2017-01-01

    Impulsivity is a behavior in everyday life of mentally healthy individuals. But in some cases the degree of impulsivity begins to create negative effects on one's life and acquires pathological connotation. Two clinical entities in which can be observed a high degree of impulsivity is Attention Deficit Hyperactivity Disorder (ADHD) and Addictive disorders. In these disorders, both impulsive act and impulsive choice are observed. According to some researchers, genetic factors are involved in the control of impulsivity. The impulsive choice, in the sense of delay discounting, may be an intermediate phenotype or endophenotype that contributes to vulnerability with respect to specific disorders in which impulsivity plays a central and decisive role. Another group of researchers argue that ADHD is one of the expressions of a more generalized disorder, known as reward-deficiency syndrome. In this syndrome, it is included increased frequency of addictive disorders. On the other hand, some researchers argue that ADHD in adolescence does not increase the likelihood of developing dependencies, when it is not accompanied by comorbidity of conduct disorders. Regarding the use of substances, there have been conflicting views in relation to etiopathogenesis of impulsivity observed in the addicted patients and whether this impulsivity precedes or follows the onset of substance use. The element that links ADHD with impaired preoccupation with gambling and has been studied most is also impulsivity. Some researchers theorize that ADHD mediates with the element of impulsivity in the development of disordered involvement with gambling in some patients. The positive correlation between impulsivity and addiction to gambling arises, whether behavioral scales or questionnaires about personality have been used. Moreover the higher measured impulsivity of the patient, the more serious are the symptoms of dependence. Abnormalities in neurotransmitter systems have been found both in patients

  17. Plasma diagnostics of low pressure high power impulse magnetron sputtering assisted by electron cyclotron wave resonance plasma

    SciTech Connect

    Stranak, Vitezslav; Herrendorf, Ann-Pierra; Drache, Steffen; Bogdanowicz, Robert; Hippler, Rainer; Cada, Martin; Hubicka, Zdenek; Tichy, Milan

    2012-11-01

    This paper reports on an investigation of the hybrid pulsed sputtering source based on the combination of electron cyclotron wave resonance (ECWR) inductively coupled plasma and high power impulse magnetron sputtering (HiPIMS) of a Ti target. The plasma source, operated in an Ar atmosphere at a very low pressure of 0.03 Pa, provides plasma where the major fraction of sputtered particles is ionized. It was found that ECWR assistance increases the electron temperature during the HiPIMS pulse. The discharge current and electron density can achieve their stable maximum 10 {mu}s after the onset of the HiPIMS pulse. Further, a high concentration of double charged Ti{sup ++} with energies of up to 160 eV was detected. All of these facts were verified experimentally by time-resolved emission spectroscopy, retarding field analyzer measurement, Langmuir probe, and energy-resolved mass spectrometry.

  18. Current-voltage-time characteristics of the reactive Ar/N{sub 2} high power impulse magnetron sputtering discharge

    SciTech Connect

    Magnus, F.; Sveinsson, O. B.; Olafsson, S.; Gudmundsson, J. T.

    2011-10-15

    The discharge current and voltage waveforms have been measured in a reactive high power impulse magnetron sputtering (HiPIMS) Ar/N{sub 2} discharge with a Ti target for 400 {mu}s long pulses. We observe that the current waveform in the reactive Ar/N{sub 2} HiPIMS discharge is highly dependent on the pulse repetition frequency, unlike the non-reactive Ar discharge. The current is found to increase significantly as the frequency is lowered. This is attributed to an increase in the secondary electron emission yield during the self-sputtering phase, when the nitride forms on the target at low frequencies. In addition, self-sputtering runaway occurs at lower discharge voltages when nitrogen is added to the discharge. This illustrates the crucial role of self-sputtering in the behavior of the reactive HiPIMS discharge.

  19. High power impulse magnetron sputtering and related discharges: scalable plasma sources for plasma-based ion implantation and deposition

    SciTech Connect

    Anders, Andre

    2009-09-01

    High power impulse magnetron sputtering (HIPIMS) and related self-sputtering techniques are reviewed from a viewpoint of plasma-based ion implantation and deposition (PBII&D). HIPIMS combines the classical, scalable sputtering technology with pulsed power, which is an elegant way of ionizing the sputtered atoms. Related approaches, such as sustained self-sputtering, are also considered. The resulting intense flux of ions to the substrate consists of a mixture of metal and gas ions when using a process gas, or of metal ions only when using `gasless? or pure self-sputtering. In many respects, processing with HIPIMS plasmas is similar to processing with filtered cathodic arc plasmas, though the former is easier to scale to large areas. Both ion implantation and etching (high bias voltage, without deposition) and thin film deposition (low bias, or bias of low duty cycle) have been demonstrated.

  20. Characterization of polycrystalline VO2 thin film with low phase transition temperature fabricated by high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Lin, Tiegui; Wang, Langping; Wang, Xiaofeng; Zhang, Yufen

    2016-04-01

    VO2 is a unique material that undergoes a reversible phase transformation around 68∘C. Currently, applications of VO2 on smart windows are limited by its high transition temperature. In order to reduce the temperature, VO2 thin film was fabricated on quartz glass substrate by high power impulse magnetron sputtering with a modulated pulsed power. The phase transition temperature has been reduced to as low as 32∘C. In addition, the VO2 film possesses a typical metal-insulator transition. X-ray diffraction and selected area electron diffraction patterns reveal that an obvious lattice distortion has been formed in the as-deposited polycrystalline VO2 thin film. X-ray photoelectron spectroscopy proves that oxygen vacancies have been formed in the as-deposited thin film, which will induce a lattice distortion in the VO2 thin film.

  1. Enhanced oxidation of TiO2 films prepared by high power impulse magnetron sputtering running in metallic mode

    NASA Astrophysics Data System (ADS)

    Stranak, V.; Kratochvil, J.; Olejnicek, J.; Ksirova, P.; Sezemsky, P.; Cada, M.; Hubicka, Z.

    2017-05-01

    A method is introduced that allows suppressing unwanted effects of target poisoning during reactive high-power impulse magnetron sputtering (R-HiPIMS) employed for deposition of oxide films. The method, based on higher reactivity of excited/activated oxygen species, is studied and demonstrated on TiO2 films deposited in R-HiPIMS discharge running very close to the metallic mode with a high deposition rate. An external source of energetic plasma that activates oxygen gas, delivered to the vicinity of the substrate, is combined with conventional R-HiPIMS of the Ti target. The activated oxygen species enable reducing the total flow rate, which simultaneously results in suppression of the target poisoning effect. On the other hand, sufficient oxidation and growth of transparent crystalline TiO2 films were observed.

  2. Mechanisms of Individual Differences in Impulsive and Risky Choice in Rats.

    PubMed

    Kirkpatrick, Kimberly; Marshall, Andrew T; Smith, Aaron P

    2015-01-01

    Individual differences in impulsive and risky choice are key risk factors for a variety of maladaptive behaviors such as drug abuse, gambling, and obesity. In our rat model, ordered individual differences are stable across choice parameters, months of testing, and span a broad spectrum, suggesting that rats, like humans, exhibit trait-level impulsive and risky choice behaviors. In addition, impulsive and risky choices are highly correlated, suggesting a degree of correlation between these two traits. An examination of the underlying cognitive mechanisms has suggested an important role for timing processes in impulsive choice. In addition, in an examination of genetic factors in impulsive choice, the Lewis rat strain emerged as a possible animal model for studying disordered impulsive choice, with this strain demonstrating deficient delay processing. Early rearing environment also affected impulsive behaviors, with rearing in an enriched environment promoting adaptable and more self-controlled choices. The combined results with impulsive choice suggest an important role for timing and reward sensitivity in moderating impulsive behaviors. Relative reward valuation also affects risky choice, with manipulation of objective reward value (relative to an alternative reference point) resulting in loss chasing behaviors that predicted overall risky choice behaviors. The combined results are discussed in relation to domain-specific versus domain-general subjective reward valuation processes and the potential neural substrates of impulsive and risky choice.

  3. Mechanisms of Individual Differences in Impulsive and Risky Choice in Rats

    PubMed Central

    Kirkpatrick, Kimberly; Marshall, Andrew T.; Smith, Aaron P.

    2016-01-01

    Individual differences in impulsive and risky choice are key risk factors for a variety of maladaptive behaviors such as drug abuse, gambling, and obesity. In our rat model, ordered individual differences are stable across choice parameters, months of testing, and span a broad spectrum, suggesting that rats, like humans, exhibit trait-level impulsive and risky choice behaviors. In addition, impulsive and risky choices are highly correlated, suggesting a degree of correlation between these two traits. An examination of the underlying cognitive mechanisms has suggested an important role for timing processes in impulsive choice. In addition, in an examination of genetic factors in impulsive choice, the Lewis rat strain emerged as a possible animal model for studying disordered impulsive choice, with this strain demonstrating deficient delay processing. Early rearing environment also affected impulsive behaviors, with rearing in an enriched environment promoting adaptable and more self-controlled choices. The combined results with impulsive choice suggest an important role for timing and reward sensitivity in moderating impulsive behaviors. Relative reward valuation also affects risky choice, with manipulation of objective reward value (relative to an alternative reference point) resulting in loss chasing behaviors that predicted overall risky choice behaviors. The combined results are discussed in relation to domain-specific versus domain-general subjective reward valuation processes and the potential neural substrates of impulsive and risky choice. PMID:27695580

  4. Impulsive control for hypervelocity missiles

    NASA Astrophysics Data System (ADS)

    Magness, R. W.

    1981-05-01

    A hypervelocity agile interceptor/quickshot is being developed for defense of ballistic missile launch sites. A guidance and control system is required to achieve the missile guidance accuracy necessary for direct target impact. Attitude control systems evaluated for the agile interceptor included aerodynamic controls, thrust vector controls and impulsive motor controls. The solid squib impulsive control motion was selected because of high response rate, low weight and low volume. A baseline motor configuration was designed and a solid propellant squib was developed for use in the control system. Ballistic pendulum and bench tests were conducted with a test impulsive control motor to measure nominal performance, establish the standard deviation of performance, and define requirements to prevent sympathetic ignition. A dynamic control wind tunnel test was also conducted to determine the impulse augmentation due to the impulsive motor jet interaction with the missile boundary layer. The degree and direction of augmentation was measured for variations in Mach number and angle of attack.

  5. IMPULSIVITY PARAMETER FOR SOLAR FLARES

    SciTech Connect

    Fajardo-Mendieta, W. G.; Alvarado-Gómez, J. D.; Calvo-Mozo, B.; Martinez-Oliveros, J. C. E-mail: bcalvom@unal.edu.co E-mail: jalvarad@eso.org

    2016-02-10

    Three phases are typically observed during solar flares: the preflare, impulsive, and decay phases. During the impulsive phase, it is believed that the electrons and other particles are accelerated after the stored energy in the magnetic field is released by reconnection. The impulsivity of a solar flare is a quantifiable property that shows how quickly this initial energy release occurs. It is measured via the impulsivity parameter, which we define as the inverse of the overall duration of the impulsive phase. We take the latter as the raw width of the most prominent nonthermal emission of the flare. We computed this observable over a work sample of 48 M-class events that occurred during the current Solar Cycle 24 by using three different methods. The first method takes into account all of the nonthermal flare emission and gives very accurate results, while the other two just cover fixed energy intervals (30–40 keV and 25–50 keV) and are useful for fast calculations. We propose an alternative way to classify solar flares according to their impulsivity parameter values, defining three different types of impulsivity, namely, high, medium, and low. This system of classification is independent of the manner used to calculated the impulsivity parameter. Lastly, we show the relevance of this tool as a discriminator of different HXR generation processes.

  6. SF6 dielectric behavior in a high voltage circuit breaker at low temperature under lightning impulses

    SciTech Connect

    Buret, F.; Beroual, A.

    1996-01-01

    This work concerns the study of the dielectric and thermodynamic behavior of SF{sub 6} in a 145 kV circuit breaker subjected to lightning impulse voltages in both polarities at temperatures varying from ambient (20 C) to {minus}45 C. The filling of the circuit breaker with SF{sub 6} is carried out at the reference point: T = 15 C, P = 6 bars abs. and d = 39.6 kg/m{sup 3}. Devices allowing to detect the appearance of local condensation of SF{sub 6} and to identify the breakdown between the circuit-breaker contacts and the flashover outside the circuit-breaker, are presented. The experimental results show a general tendency to a decrease in the U{sub 50%} voltage when the temperature is decreased at constant density (a decrease by about 5% when the temperature was decreased from +20 C to {minus}25 C). Such a variation would not have a significant influence in industrial practice. Even if this variation is very weak, it also appears from the obtained results that the gas density is not the only parameter which has an influence on the electric strength of the gas. However, to compare results at different temperatures, it would be better to make it at constant density and not at constant pressure, to avoid the dependency of the ratio (E/N) on N (where E is the electric strength and N the density). On the other hand, it seems that the presence of the liquid in the circuit breaker is not a penalizing parameter. The distribution of the electric field corresponding to the geometrical configuration of the studied circuit-breaker is also presented.

  7. Impulsive choice and environmental enrichment: effects of d-amphetamine and methylphenidate.

    PubMed

    Perry, Jennifer L; Stairs, Dustin J; Bardo, Michael T

    2008-11-03

    Individual differences in impulsive choice and rearing in differential environments are factors that predict vulnerability to drug abuse. The present study determined if rearing influences impulsive choice, and if d-amphetamine or methylphenidate alters impulsive choice in differentially reared rats. Male Sprague-Dawley rats were raised from 21 days of age in either an enriched condition (EC) or an isolated condition (IC) and were tested as young adults on an adjusting delay task. In this task, two levers were available and a response on one lever yielded one 45mg food pellet immediately, whereas a response on the other yielded three pellets after an adjusting delay. The delay was initially set at 6s, and it decreased or increased by 1s following responses on the immediate or delayed levers, respectively. A mean adjusted delay (MAD) was calculated upon completion of each daily session, and it served as the quantitative measure of impulsivity. Once MADs stabilized, rats were injected with saline, d-amphetamine (0.5, 1.0, or 2.0mg/kg, s.c.), or methylphenidate (2.5, 5.0, or 10.0mg/kg, s.c.) 15min prior to adjusting delay sessions. EC rats had higher baseline MADs (were less impulsive) than IC rats. Additionally, administration of d-amphetamine, but not methylphenidate, dose-dependently increased impulsive choice (decreased MADs) in EC rats. In IC rats, d-amphetamine and methylphenidate dose-dependently decreased impulsivity (increased MADs). These results indicate that rearing environment influences impulsive choice and moderates the effect of psychostimulants on impulsive choice. Specifically, psychostimulants may decrease environment-dependent impulsive choice in individuals with high levels of impulsivity (e.g., those with ADHD), whereas they may increase impulsive choice in individuals with low levels of impulsivity.

  8. Reward processing deficits and impulsivity in high-risk offspring of alcoholics: A study of event-related potentials during a monetary gambling task

    PubMed Central

    Kamarajan, Chella; Pandey, Ashwini K.; Chorlian, David B.; Manz, Niklas; Stimus, Arthur T.; Bauer, Lance O.; Hesselbrock, Victor M.; Schuckit, Marc A.; Kuperman, Samuel; Kramer, John; Porjesz, Bernice

    2015-01-01

    Background Individuals at high risk to develop alcoholism often manifest neurocognitive deficits as well as increased impulsivity. The goal of the present study is to elucidate reward processing deficits, externalizing disorders, and impulsivity as elicited by electrophysiological, clinical and behavioral measures in subjects at high risk for alcoholism from families densely affected by alcoholism in the context of brain maturation across age groups and gender. Methods Event-related potentials (ERPs) and current source density (CSD) during a monetary gambling task (MGT) were measured in 12–25 year old offspring (N = 1864) of families in the Collaborative Study on the Genetics of Alcoholism (COGA) Prospective study; the high risk (HR, N = 1569) subjects were from families densely affected with alcoholism and the low risk (LR, N = 295) subjects were from community families. Externalizing disorders and impulsivity scores were also compared between LR and HR groups. Results HR offspring from older (16–25 years) male and younger (12–15 years) female subgroups showed lower P3 amplitude than LR subjects. The amplitude decrement was most prominent in HR males during the loss condition. Overall, P3 amplitude increase at anterior sites and decrease at posterior areas were seen in older compared to younger subjects, suggesting frontalization during brain maturation. The HR subgroups also exhibited hypofrontality manifested as weaker CSD activity during both loss and gain conditions at frontal regions. Further, the HR subjects had higher impulsivity scores and increased prevalence of externalizing disorders. P3 amplitudes during the gain condition were negatively correlated with impulsivity scores. Conclusions Older male and younger female HR offspring, compared to their LR counterparts, manifested reward processing deficits as indexed by lower P3 amplitude and weaker CSD activity, along with higher prevalence of externalizing disorders and higher impulsivity scores

  9. Telomere length is highly inherited and associated with hyperactivity-impulsivity in children with attention deficit/hyperactivity disorder

    PubMed Central

    Costa, Danielle de Souza; Rosa, Daniela Valadão Freitas; Barros, Alexandre Guimarães Almeida; Romano-Silva, Marco Aurélio; Malloy-Diniz, Leandro Fernandes; Mattos, Paulo; de Miranda, Débora Marques

    2015-01-01

    Telomere length (TL) is highly heritable, and a shorter telomere at birth may increase the risk of age-related problems. Additionally, a shorter TL may represent a biomarker of chronic stress and has been associated with psychiatric disorders. However, no study has explored whether there is an association between TL and the symptoms of one of the most common neurodevelopmental disorders in childhood: Attention Deficit/Hyperactive Disorder (ADHD). We evaluated 61 (range, 6–16 years) ADHD children and their parents between 2012 and 2014. TL was measured with a quantitative polymerase chain reaction method with telomere signal normalized to the signal from a single copy gene (36B4) to generate a T/S ratio. Family data was processed through a generalized estimated equations (GEE) model to determine the effect of parental TL on children TL. Inattentive and hyperactive-impulsive symptoms were also evaluated in relation to TL. For the first time, we found general heritability to be the major mechanism explaining interindividual TL variation in ADHD (father-child: 95% CI = 0.35/0.91, p < 0.001; mother-child: 95% CI = 0.38/0.74, p < 0.001). The hyperactive-impulsive dimension of ADHD was related with children’s TL (r = −339, p = 0.008) and maternal TL (r = −264, p = 0.047), but not with paternal TL (p > 0.05). The ADHD inattentive dimension was not significant associated with TL in this study (p > 0.05). TL was shown to be a potential biomarker of the ADHD symptoms burden in families affected by this neurodevelopmental disorder. However, it is crucial that future studies investigating the rate of telomere attrition in relation to psychiatric problems to consider the strong determination of TL at birth by inheritance. PMID:26217174

  10. Impulse Control and Anxiety Related to School Adjustment and Academic Achievement among High School Males. Final Report: Office of Education Project S-484.

    ERIC Educational Resources Information Center

    Barratt, Ernest S.

    The author attempts to determine the value of psychometric measures of impulsiveness and anxiety for predicting potential disciplinary problems among high school males. A secondary purpose is to relate these personality factors to academic achievement. Approximately 320 sophomores were administered a psychometric battery which included: (1) an…

  11. Relations among Academic Enablers and Academic Achievement in Children with and without High Levels of Parent-Rated Symptoms of Inattention, Impulsivity, and Hyperactivity

    ERIC Educational Resources Information Center

    Demaray, Michelle Kilpatrick; Jenkins, Lyndsay N.

    2011-01-01

    This study examined the relationships among academic enablers (i.e., engagement, interpersonal skills, motivation, study skills) and academic achievement in children with and without high levels of parent-rated symptoms of inattention, impulsivity, and hyperactivity (Symptoms of IIH Group). The study included 69 participants (29 [42%] in the IIH…

  12. Relations among Academic Enablers and Academic Achievement in Children with and without High Levels of Parent-Rated Symptoms of Inattention, Impulsivity, and Hyperactivity

    ERIC Educational Resources Information Center

    Demaray, Michelle Kilpatrick; Jenkins, Lyndsay N.

    2011-01-01

    This study examined the relationships among academic enablers (i.e., engagement, interpersonal skills, motivation, study skills) and academic achievement in children with and without high levels of parent-rated symptoms of inattention, impulsivity, and hyperactivity (Symptoms of IIH Group). The study included 69 participants (29 [42%] in the IIH…

  13. Separation methods for high specific activity radioarsenic

    NASA Astrophysics Data System (ADS)

    Jurisson, S. S.; Wycoff, D. E.; DeGraffenreid, A.; Embree, M. F.; Ketring, A. R.; Cutler, C. S.; Fassbender, M. E.; Ballard, B.

    2012-12-01

    Radiopharmaceuticals require the use of high specific activity radionuclides, especially when targeting limited numbers of receptors on tumor surfaces. Two radioisotopes of arsenic (72As and 77As) are potentially useful in diagnostic and therapeutic radiopharmaceuticals. Methods for the production, separation, and isolation of high specific activity 72As and 77As are presented.

  14. Impulse-based methods for fluid flow

    SciTech Connect

    Cortez, Ricardo

    1995-05-01

    A Lagrangian numerical method based on impulse variables is analyzed. A relation between impulse vectors and vortex dipoles with a prescribed dipole moment is presented. This relation is used to adapt the high-accuracy cutoff functions of vortex methods for use in impulse-based methods. A source of error in the long-time implementation of the impulse method is explained and two techniques for avoiding this error are presented. An application of impulse methods to the motion of a fluid surrounded by an elastic membrane is presented.

  15. Emotion Regulation and Impulsivity in Young Adults

    PubMed Central

    Schreiber, Liana R.N.; Grant, Jon E.; Odlaug, Brian L.

    2012-01-01

    Past research has linked both emotion regulation and impulsivity with the development and maintenance of addictions. However, no research has investigated the relationship between emotion regulation and impulsivity within young adults. In the present study, we analyzed 194 young adults (27.8% female; 21.3 ± 3.32 years old; 91.8% single; 85.1% Caucasian), grouping them as low, average, or high emotionally dysregulated, and compared self-reported impulsivity, impulsive behaviors (such as alcohol and substance use and gambling) and cognitive impulsivity. We hypothesized that those with high levels of emotion dysregulation would score higher on self-reported and cognitive impulsivity, and report more impulsive behaviors. Analysis indicated that compared to low, the high emotion dysregulation group scored significantly higher on two self-report measures of impulsivity, harm avoidance, and cognitive reasoning. No significant differences were found between groups in impulsive behaviors and cognitive impulsivity. Overall, this study highlights the relationship between emotion dysregulation and impulsivity, suggesting that emotion regulation may be an important factor to consider when assessing individuals at a higher risk for developing an addiction. PMID:22385661

  16. Functional impulsivity and reinforcement sensitivity theory.

    PubMed

    Smillie, Luke D; Jackson, Chris J

    2006-02-01

    In this article, we attempt to integrate Dickman's (1990) descriptive concept of Functional Impulsivity (FI) with Gray's (1970, 1991) Reinforcement Sensitivity Theory (RST). Specifically, we consider that FI bears great conceptual similarity to Gray's concept of reward-reactivity, which is thought to be caused by the combined effects of a Behavioral Activation System (BAS) and Behavioral Inhibition System (BIS). In our first study, we examine the construct validity and structural correlates of FI. Results indicate that FI is related positively to measures of BAS and Extraversion, negatively to measures of BIS and Neuroticism, and is separate from Psychoticism and typical trait Impulsivity, which Dickman calls Dysfunctional Impulsivity (DI). In our second study, we use a go/no-go discrimination task to examine the relationship between FI and response bias under conditions of rewarding and punishing feedback. Results indicate that FI, along with two measures of BAS, predicted the development of a response bias for the rewarded alternative. In comparison, high DI appeared to reflect indifference toward either reward or punishment. We consider how these findings might reconcile the perspectives of Gray and Dickman and help clarify the broader understanding of Impulsivity.

  17. Impulsivity, perceived self-regulatory success in dieting, and body mass in children and adolescents: A moderated mediation model.

    PubMed

    Meule, Adrian; Hofmann, Johannes; Weghuber, Daniel; Blechert, Jens

    2016-12-01

    Impulsivity has been suggested to contribute to overeating and obesity. However, findings are inconsistent and it appears that only specific facets of impulsivity are related to eating-related variables and to body mass. In the current study, relationships between self-reported impulsivity, perceived self-regulatory success in dieting, and objectively measured body mass were examined in N = 122 children and adolescents. Scores on attentional and motor impulsivity interactively predicted perceived self-regulatory success in dieting, but not body mass: Higher attentional impulsivity was associated with lower perceived self-regulatory success at high levels of motor impulsivity, but not at low levels of motor impulsivity. A moderated mediation model revealed an indirect effect of attentional and motor impulsivity on body mass, which was mediated by perceived self-regulatory success in dieting. Thus, results show that only specific facets of impulsivity are relevant in eating- and weight-regulation and interact with each other in the prediction of these variables. These facets of impulsivity, however, are not directly related to higher body mass, but indirectly via lower success in eating-related self-regulation in children and adolescents.

  18. The uncompetitive NMDA receptor antagonists ketamine and memantine preferentially increase the choice for a small, immediate reward in low-impulsive rats

    PubMed Central

    Iemolo, Attilio; Narayan, Aditi R.; Kwak, Jina; Momaney, Duncan

    2012-01-01

    Rationale Impulsive behavior is categorically differentiated between impulsive action, the inability to withhold from acting out a response, and impulsive choice, the greater preference for an immediate and smaller reward over a delayed but more advantageous reward. While the effects of N-methyl-D-aspartic acid (NMDA) receptor antagonists on impulsive action have been extensively characterized, there are very few and conflicting reports on the effects of this class of drugs on impulsive choice. Objectives Using a modified adjusting delay task, we investigated the effects of uncompetitive and competitive blockade of NMDA receptors on impulsive choice. Methods Male Wistar rats were trained in a modified adjusting delay task, which involved repeated choice between a low reinforcing solution delivered immediately and a highly reinforcing solution delivered after a variable delay. Rats were then administered either the NMDA receptor uncompetitive antagonists ketamine or memantine, or the competitive antagonists D-AP-5 or CGS 19755. Results Ketamine treatment dose-dependently increased impulsive choice, and this effect was selective for low-impulsive but not high-impulsive rats. Similarly, memantine treatment dose-dependently increased impulsive choice with a preferential effect for low-impulsive rats. While D-AP-5 treatment did not affect impulsive choice, CGS 19755 increased impulsivity, however, at the same doses at which it caused a marked response inhibition. Conclusions NMDA receptor uncompetitive, but not competitive, antagonists significantly increased impulsive choice, preferentially in low-impulsive rats. These findings demonstrate that the effects of NMDA receptor blockade on impulsive choice are not generalizable and depend on the specific mechanism of action of the antagonist used. PMID:23104264

  19. Does lightning destroy rocks?: Results from a laboratory lightning experiment using an impulse high-current generator

    NASA Astrophysics Data System (ADS)

    Wakasa, Sachi A.; Nishimura, Seisuke; Shimizu, Hiroyuki; Matsukura, Yukinori

    2012-08-01

    To understand the destruction of rocks and changes to landforms by lightning strikes, laboratory experiments of lightning strikes were performed using three kinds of rock samples as targets. Artificial lightning with known electric current was simulated by an impulse high-current generator in the laboratory. The artificial lightning is different to natural lightning. The high-current generator can generate up to 20 kA of electric current equal to 50% of the value of natural lightning, but up to 50 kV of electric voltage which is a tenth to hundredth that of natural lightning. Experimental results showed that the rock samples with low mechanical resistance, tuff and rhyolite, were destroyed, while the rock sample with high mechanical resistance, i.e., granite, was not broken by lightning strikes. These results indicate that natural lightning causes rocks and bedrock to break. These imply that lightning might change landforms, for example gnammas and fractures on tors and mountain peaks where lightning tends to strike.

  20. Time resolved ion energy distribution functions of non-reactive and reactive high power impulse magnetron sputtering of titanium

    NASA Astrophysics Data System (ADS)

    Grosse, Katharina; Breilmann, Wolfgang; Maszl, Christian; Benedikt, Jan; von Keudell, Achim

    2016-09-01

    High power impulse magnetron sputtering (HiPIMS) is a technique for thin film deposition and can be operated in reactive and non-reactive mode. The growth rate of HiPIMS in non-reactive mode reduces to 30% compared to direct current magnetron sputtering (dcMS) at same average power. However, the quality of the coatings produced with HiPIMS is excellent which makes these plasmas highly appealing. In reactive mode target poisoning is occurring which changes the plasma dynamics. An advantage of reactive HiPIMS is that it can be operated hysteresis-free which can result in a higher growth rate compared to dcMS. In this work thin films are deposited by a HiPIMS plasma which is generated by short pulses of 100 μs with high power densities in the range of 1 kW/cm2. Ar and Ar/N2 admixtures are used as a working gas to sputter a 2'' titanium target. The particle transport is analysed with time resolved ion energy distribution functions which are measured by a mass spectrometer with a temporal resolution of 2 μs. Phase resolved optical emission spectroscopy is executed to investigate the particle dynamics of different species. The time and energy resolved particle fluxes in non-reactive and reactive mode are compared and implications on the sputter process are discussed.

  1. Physics of Plasma-Based Ion Implantation&Deposition (PBIID)and High Power Impulse Magnetron Sputtering (HIPIMS): A Comparison

    SciTech Connect

    Anders, Andre

    2007-08-28

    The emerging technology of High Power Impulse MagnetronSputtering (HIPIMS) has much in common with the more establishedtechnology of Plasma Based Ion Implantation&Deposition (PBIID):both use pulsed plasmas, the pulsed sheath periodically evolves andcollapses, the plasma-sheath system interacts with the pulse-drivingpower supply, the plasma parameters are affected by the power dissipated,surface atoms are sputtered and secondary electrons are emitted, etc.Therefore, both fields of science and technology could learn from eachother, which has not been fully explored. On the other hand, there aresignificant differences, too. Most importantly, the operation of HIPIMSheavilyrelies on the presence of a strong magnetic field, confiningelectrons and causing their ExB drift, which is closed for typicalmagnetron configurations. Second, at the high peak power levels used forHIPIMS, 1 kW/cm2 or greater averaged over the target area, the sputteredmaterial greatly affects plasma generation. For PBIID, in contrast,plasma generation and ion processing of the surface (ion implantation,etching, and deposition) are considered rela-tively independentprocesses. Third, secondary electron emission is generally considered anuisance for PBIID, especially at high voltages, whereas it is a criticalingredient to the operation of HIPIMS. Fourth, the voltages in PBIID areoften higher than in HIPIMS. For the first three reasons listed above,modelling of PBIID seems to be easier and could give some guidance forfuture HIPIMS models, which, clearly, will be more involved.

  2. Constrained sheath optics for high thrust density, low specific impulse ion thrusters

    NASA Technical Reports Server (NTRS)

    Wilbur, Paul J.; Han, Jian-Zhang

    1987-01-01

    The results of an experimental study showing that a contoured, fine wire mesh attached to the screen grid can be used to control the divergence characteristics of ion beamlets produced at low net-to-total accelerating voltage ratios are presented. The influence of free and constrained-sheath optics systems on beamlet divergence characteristics are found to be similar in the operating regime investigated, but it was found that constrained-sheath optics systems can be operated at higher perveance levels than free-sheath ones. The concept of a fine wire interference probe that can be used to study ion beamlet focusing behavior is introduced. This probe is used to demonstrate beamlet focusing to a diameter about one hundreth of the screen grid extraction aperture diameter. Additional testing is suggested to define an optimally contoured mesh that could yield well focused beamlets at net-to-total accelerating voltage ratios below about 0.1.

  3. Laser-Powered Thrusters for High Efficiency Variable Specific Impulse Missions (Preprint)

    DTIC Science & Technology

    2007-04-10

    OF LASER ABLATION PROPULSION LOW TOXICITY FUELS AND COMBUSTION PRODUCTS In our Laser Plasma Microthruster, Glycidyl Azide Polymer (GAP) is the...If the surface is a passive (i.e., non -exothermic) material, inertial confinemt fusion theory allows us to derive expressions for Cm and Isp:4 (16...17) allows us to estimate Isp, where Ψ = (A/2)[Z2(Z+1)]1/3, A is the mean atomic mass number and Z the mean ionic charge in the laser-plasma plume

  4. Method to control deposition rate instabilities—High power impulse magnetron sputtering deposition of TiO{sub 2}

    SciTech Connect

    Kossoy, Anna E-mail: anna.kossoy@gmail.com; Magnusson, Rögnvaldur L.; Tryggvason, Tryggvi K.; Leosson, Kristjan; Olafsson, Sveinn

    2015-03-15

    The authors describe how changes in shutter state (open/closed) affect sputter plasma conditions and stability of the deposition rate of Ti and TiO{sub 2} films. The films were grown by high power impulse magnetron sputtering in pure Ar and in Ar/O{sub 2} mixture from a metallic Ti target. The shutter state was found to have an effect on the pulse waveform for both pure Ar and reactive sputtering of Ti also affecting stability of TiO{sub 2} deposition rate. When the shutter opened, the shape of pulse current changed from rectangular to peak-plateau and pulse energy decreased. The authors attribute it to the change in plasma impedance and gas rarefaction originating in geometry change in front of the magnetron. TiO{sub 2} deposition rate was initially found to be high, 1.45 Å/s, and then dropped by ∼40% during the first 5 min, while for Ti the change was less obvious. Instability of deposition rate poses significant challenge for growing multilayer heterostructures. In this work, the authors suggest a way to overcome this by monitoring the integrated average energy involved in the deposition process. It is possible to calibrate and control the film thickness by monitoring the integrated pulse energy and end growth when desired integrated pulse energy level has been reached.

  5. Patterns of disturbed impulse propagation in multiple sclerosis identified by low and high frequency somatosensory evoked potential components.

    PubMed

    Gobbelé, René; Waberski, Till Dino; Dieckhöfer, Anne; Kawohl, Wolfram; Klostermann, Fabian; Curio, Gabriel; Buchner, Helmut

    2003-01-01

    In human median nerve somatosensory evoked potentials (SSEPs), high frequency (600 Hz) oscillations (HFOs) are superimposed onto the low frequency SSEP component N20. High frequency oscillations are generated both in deep axon segments of thalamo-cortical projection neurons and at the primary somatosensory cortex. The present study aimed to test the hypothesis that HFOs might be more sensitive to temporal dispersion caused by demyelinating lesions in multiple sclerosis (MS) than the N20. The authors recorded HFOs in median nerve SSEPs in 50 patients with definite MS and in 30 healthy controls. Three patterns of SSEP alterations were found: (1) abolished HFOs with either normal (11% of stimulated limbs), or delayed N20 (16% of stimulated limbs); (2) an attenuation of N20 amplitude with preserved HFOs (13%); and (3) a mixture of both patterns (21%). The first pattern--normal N20 with abolished HFOs--indicates that the HFOs are a sensitive marker of slight demyelination. The second pattern is suggestive of a mainly axonal lesion type, while the third pattern points to a combined axonal/demyelinating process or a conduction block. Analysis of HFOs allows identification of slight demyelinating processes in MS patients in whom the N20 SSEP component remains unaffected. The HFOs provide a tool to distinguish different patterns of disturbed impulse propagation.

  6. Educational Specifications: University City High School.

    ERIC Educational Resources Information Center

    Philadelphia School District, PA.

    Educational specifications are presented delineating instructional space requirements and relationships for a new high school in Philadelphia, Pennsylvania. These specifications comprise a set of written instructions from which the architect can derive a design concept compatible with current educational needs and adaptable to future changes in…

  7. Trait impulsivity and impaired prefrontal impulse inhibition function in adolescents with internet gaming addiction revealed by a Go/No-Go fMRI study

    PubMed Central

    2014-01-01

    Background Recent studies suggest that Internet gaming addiction (IGA) is an impulse disorder, or is at least related to impulse control disorders. In the present study, we hypothesized that different facets of trait impulsivity may be specifically linked to the brain regions with impaired impulse inhibition function in IGA adolescents. Methods Seventeen adolescents with IGA and seventeen healthy controls were scanned during performance of a response-inhibition Go/No-Go task using a 3.0 T MRI scanner. The Barratt Impulsiveness Scale (BIS)-11 was used to assess impulsivity. Results There were no differences in the behavioral performance on the Go/No-Go task between the groups. However, the IGA group was significantly hyperactive during No-Go trials in the left superior medial frontal gyrus, right anterior cingulate cortex, right superior/middle frontal gyrus, left inferior parietal lobule, left precentral gyrus, and left precuneus and cuneus. Further, the bilateral middle temporal gyrus, bilateral inferior temporal gyrus, and right superior parietal lobule were significantly hypoactive during No-Go trials. Activation of the left superior medial frontal gyrus was positively associated with BIS-11 and Chen Internet Addiction Scale (CIAS) total score across IGA participants. Conclusions Our data suggest that the prefrontal cortex may be involved in the circuit modulating impulsivity, while its impaired function may relate to high impulsivity in adolescents with IGA, which may contribute directly to the Internet addiction process. PMID:24885073

  8. Impulsive behaviour in interpersonal encounters: associations with quarrelsomeness and agreeableness.

    PubMed

    aan Het Rot, Marije; Moskowitz, D S; Young, Simon N

    2015-02-01

    Associations between impulsivity and interpersonal behaviours have rarely been examined, even though impulsivity may disrupt the flow of social interactions. For example, it is unknown to what extent the commonly used Barratt Impulsiveness Scale (BIS-11) predicts impulsive behaviour in social situations, and how behaving impulsively during interpersonal encounters might influence levels of quarrelsomeness and agreeableness. In this study, 48 healthy working individuals completed the BIS-11 and recorded their behaviour in social situations using event-contingent recording. Record forms included items representing quarrelsome, agreeable, and impulsive behaviours. BIS-11 motor impulsiveness scores predicted impulsive behaviour in social situations. Impulsive behaviour was associated, in different interactions, with both agreeableness and quarrelsomeness. Behaving impulsively in specific interactions was negatively associated with agreeableness in participants with higher BIS-11 motor impulsiveness and positively associated with agreeableness in participants with lower BIS-11 motor impulsiveness. Impulsive quarrelsome behaviour may cause interpersonal problems. Impulsive agreeable behaviour may have positive effects in individuals with low trait impulsivity. The idea that there are between-person differences in the effects of state impulsivity on the flow of social interaction deserves further study.

  9. Influence of high power impulse magnetron sputtering plasma ionization on the microstructure of TiN thin films

    NASA Astrophysics Data System (ADS)

    Ehiasarian, A. P.; Vetushka, A.; Gonzalvo, Y. Aranda; Sáfrán, G.; Székely, L.; Barna, P. B.

    2011-05-01

    HIPIMS (High Power Impulse Magnetron Sputtering) discharge is a new PVD technology for the deposition of high-quality thin films. The deposition flux contains a high degree of metal ionization and nitrogen dissociation. The microstructure of HIPIMS-deposited nitride films is denser compared to conventional sputter technologies. However, the mechanisms acting on the microstructure, texture and properties have not been discussed in detail so far. In this study, the growth of TiN by HIPIMS of Ti in mixed Ar and N2 atmosphere has been investigated. Varying degrees of metal ionization and nitrogen dissociation were produced by increasing the peak discharge current (Id) from 5 to 30 A. The average power was maintained constant by adjusting the frequency. Mass spectrometry measurements of the deposition flux revealed a high content of ionized film-forming species, such as Ti1+, Ti2+ and atomic nitrogen N1+. Ti1+ ions with energies up to 50 eV were detected during the pulse with reducing energy in the pulse-off times. Langmuir probe measurements showed that the peak plasma density during the pulse was 3 × 1016 m-3. Plasma density, and ion flux ratios of N1+: N21+ and Ti1+: Ti0 increased linearly with peak current. The ratios exceeded 1 at 30 A. TiN films deposited by HIPIMS were analyzed by X-ray diffraction, and transmission electron microscopy. At high Id, N1+: N21+> 1 and Ti1+: Ti0> 1 were produced; a strong 002 texture was present and column boundaries in the films were atomically tight. As Id reduced and N1+: N21+ and Ti1+: Ti0 dropped below 1, the film texture switched to strong 111 with a dense structure. At very low Id, porosity between columns developed. The effects of the significant activation of the deposition flux observed in the HIPIMS discharge on the film texture, microstructure, morphology and properties are discussed.

  10. Fast charge exchange ions in high power impulse magnetron sputtering of titanium as probes for the electrical potential

    NASA Astrophysics Data System (ADS)

    Breilmann, W.; Maszl, C.; von Keudell, A.

    2017-03-01

    High power impulse magnetron sputtering (HiPIMS) plasmas exhibit a high ionization fraction of the sputtered material and ions with high kinetic energies, which produce thin films with superior quality. These ion energy distribution functions (IEDF) contain energetic peaks, which are believed to be linked to a distinct electrical potential hump {{Δ }}{{{Φ }}}{{ionization}{{zone}}} inside rotating localized ionization zones, so called spokes, at target power densities above 1 kW cm‑2. Any direct measurement of this electrical potential structure is, however, very difficult due to the dynamic nature of the spokes and the very high local power density, which hampers the use of conventional emissive probes. Instead, we use a careful analysis of the IEDFs for singly and doubly charged titanium ions from a HiPIMS plasma at varying target power density. The energy peaks in the IEDFs measured at the substrate depend on the point of ionization and any charge exchange collisions on the path between ionization and impact at the substrate. Thereby, the IEDFs contain a convoluted information about the electrical potential structure inside the plasma. The analysis of these IEDFs reveal that higher ionization states originate at high target power densities from the central part of the plasma spoke, whereas singly charged ions originate from the perimeter of the plasma spoke. Consequently, we observe different absolute ion energies with the energy of Ti2+ being slightly higher than two times the energy of Ti+. Additional peaks are observed in the IEDFs of Ti+ originating from charge exchange reactions from Ti2+ and Ti3+ with titanium neutrals. Based on this analysis of the IEDFs, the structure of the electrical potential inside a spoke is inferred yielding {{Δ }}{{{Φ }}}{{ionization}{{zone}}} = 25 V above the plasma potential, irrespective of target power density.

  11. Return of target material ions leads to a reduced hysteresis in reactive high power impulse magnetron sputtering: Experiment

    NASA Astrophysics Data System (ADS)

    Čapek, Jiří; Kadlec, Stanislav

    2017-05-01

    Titanium and aluminum targets have been reactively sputtered in Ar +O2 or Ar +N2 gas mixtures in order to systematically investigate the effect of reduced hysteresis in reactive high power impulse magnetron sputtering (HiPIMS) as compared to other sputtering techniques utilizing low discharge target power density (e.g., direct current or pulsed direct current mid-frequency magnetron sputtering) operated at the same average discharge power. We found that the negative slope of the flow rate of the reactive gas gettered by the sputtered target material as a function of the reactive gas partial pressure is clearly lower in the case of HiPIMS. This results in a lower critical pumping speed, which implies a reduced hysteresis. We argue that the most important effect explaining the observed behavior is covering of the reacted areas of the target by the returning ionized metal, effectively lowering the target coverage at a given partial pressure. This explanation is supported by a calculation using an analytical model of reactive HiPIMS with time and space averaging (developed by us).

  12. System for time-resolved laser absorption spectroscopy and its application to high-power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Adámek, P.; Olejníček, J.; Hubička, Z.; Čada, M.; Kment, Š.; Kohout, M.; Do, H. T.

    2017-02-01

    This paper deals with the development and construction of an apparatus for time-resolved tunable diode laser absorption spectroscopy (LAS) for the diagnostics of pulsed plasma. A detailed description of the extension of a progressive method of laser absorption spectroscopy in continuous regime to a direct triggering method of the time-resolved laser absorption spectroscopy (TR-LAS) is presented. The main advantage of the developed method is its capability to measure the time evolution of the whole absorption profile with a preset time resolution, which can be less than 1 μs. Therefore, the presented method of repetitive sampling applied on LAS in plasma processes is capable of simultaneous measurement of the density and kinetic temperature of selected particles. Its appropriate applications are to periodical processes in technological plasma, namely pulsed plasma discharges. The developed method of TR-LAS was applied to measurements of the temporal evolution of density and kinetic temperature of argon metastable species during high-power impulse magnetron sputtering of titanium and titanium dioxide thin films.

  13. Formation of hydrogenated amorphous carbon films by reactive high power impulse magnetron sputtering containing C2H2 gas

    NASA Astrophysics Data System (ADS)

    Kimura, Takashi; Kamata, Hikaru

    2015-09-01

    Diamond-like carbon (DLC) films have attracted interest for material industries, because they have unique properties. Hydrogenated amorphous carbon films are prepared by reactive high power impulse magnetron sputtering (HiPIMS) containing C2H2 gas and the properties of the films produced in Ar/C2H2 and Ne/C2H2 HiPIMS are compared. Production of hydrocarbon radicals and their ions strongly depends on both electron temperature and electron density in HiPIMS. Therefore, the influence of the difference in buffer gas (Ar and Ne) on the film properties is also valuable to investigate. The film preparation is performed at an average power of 60 W and a repetition frequency of 110 Hz. Total pressure ranges between 0.3 and 2 Pa. The maximum of instantaneous power is about 20-25 kW, and the magnitude of the current is 35 A. A negative pulse voltage is applied to the substrates for about 15 μs after the target voltage changed from about -500 V to 0 V. Hardness of the films prepared by Ar/C2H2 HiPIMS monotonically decreases with increasing the total pressure, whereas that of the films prepared by Ne/C2H2 HiPIMS does not strongly depend on the total pressure. This work is partially supported by JSPS KAKENHI Grant Number 26420230.

  14. An ionization region model of the reactive Ar/O2 high power impulse magnetron sputtering discharge

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Jon Tomas; Lundin, Daniel; Brenning, Nils; Raadu, Michel A.; Huo, Chunqing; Minea, Tiberiu

    2016-09-01

    A reactive ionization region model (R-IRM) is developed to describe the reactive Ar/O2 high power impulse magnetron sputtering (HiPIMS) discharge with titanium target. We compare the discharge properties when the discharge is operated in the two well established operating modes, the metal mode and the poisoned mode. Experimentally, it is found that in the metal mode the discharge current waveform displays a typical non-reactive evolution, while in the poisoned mode the discharge current waveform becomes distinctly triangular and the current increases significantly. Using the R-IRM we find that when the discharge is operated in the metal mode Ar+ and Ti+-ions contribute most significantly (roughly equal amounts) to the discharge current while in the poisoned mode the Ar+-ions contribute most significantly to the discharge current while the contribution of O+-ions and secondary electron emission is much smaller. Furthermore, we find that recycling of ionized atoms coming from the target are required for the current generation in both modes of operation. In the metal mode self-sputter recycling dominates and in the poisoned mode working gas recycling dominates, and it is concluded that the dominating type of recycling determines the discharge current waveform.

  15. High power impulse magnetron sputtering: Current-voltage-time characteristics indicate the onset of sustained self-sputtering

    NASA Astrophysics Data System (ADS)

    Anders, André; Andersson, Joakim; Ehiasarian, Arutiun

    2007-12-01

    The commonly used current-voltage characteristics are found inadequate for describing the pulsed nature of the high power impulse magnetron sputtering (HIPIMS) discharge; rather, the description needs to be expanded to current-voltage-time characteristics for each initial gas pressure. Using different target materials (Cu, Ti, Nb, C, W, Al, and Cr) and a pulsed constant-voltage supply, it is shown that the HIPIMS discharges typically exhibit an initial pressure dependent current peak followed by a second phase that is power and material dependent. This suggests that the initial phase of a HIPIMS discharge pulse is dominated by gas ions, whereas the later phase has a strong contribution from self-sputtering. For some materials, the discharge switches into a mode of sustained self-sputtering. The very large differences between materials cannot be ascribed to the different sputter yields but they indicate that generation and trapping of secondary electrons play a major role for current-voltage-time characteristics. In particular, it is argued that the sustained self-sputtering phase is associated with the generation of multiply charged ions because only they can cause potential emission of secondary electrons, whereas the yield caused by singly charged metal ions is negligibly small.

  16. Return of target material ions leads to a reduced hysteresis in reactive high power impulse magnetron sputtering: Model

    NASA Astrophysics Data System (ADS)

    Kadlec, Stanislav; Čapek, Jiří

    2017-05-01

    A tendency to disappearing hysteresis in reactive High Power Impulse Magnetron Sputtering (HiPIMS) has been reported previously without full physical explanation. An analytical model of reactive pulsed sputtering including HiPIMS is presented. The model combines a Berg-type model of reactive sputtering with the global HiPIMS model of Christie-Vlček. Both time and area averaging is used to describe the macroscopic steady state, especially the reactive gas balance in the reactor. The most important effect in the presented model is covering of reacted parts of target by the returning ionized metal, effectively lowering the target coverage by reaction product at a given partial pressure. The return probability of ionized sputtered metal has been selected as a parameter to quantify the degree of HiPIMS effects. The model explains the reasons for reduced hysteresis in HiPIMS. The critical pumping speed was up to a factor of 7 lower in reactive HiPIMS compared to the mid-frequency magnetron sputtering. The model predicts reduced hysteresis in HiPIMS due to less negative slope of metal flux to substrates and of reactive gas sorption as functions of reactive gas partial pressure. Higher deposition rate of reactive HiPIMS compared to standard reactive sputtering is predicted for some parameter combinations. Comparison of the model with experiment exhibits good qualitative and quantitative agreement for three material combinations, namely, Ti-O2, Al-O2, and Ti-N2.

  17. System for time-resolved laser absorption spectroscopy and its application to high-power impulse magnetron sputtering.

    PubMed

    Adámek, P; Olejníček, J; Hubička, Z; Čada, M; Kment, Š; Kohout, M; Do, H T

    2017-02-01

    This paper deals with the development and construction of an apparatus for time-resolved tunable diode laser absorption spectroscopy (LAS) for the diagnostics of pulsed plasma. A detailed description of the extension of a progressive method of laser absorption spectroscopy in continuous regime to a direct triggering method of the time-resolved laser absorption spectroscopy (TR-LAS) is presented. The main advantage of the developed method is its capability to measure the time evolution of the whole absorption profile with a preset time resolution, which can be less than 1 μs. Therefore, the presented method of repetitive sampling applied on LAS in plasma processes is capable of simultaneous measurement of the density and kinetic temperature of selected particles. Its appropriate applications are to periodical processes in technological plasma, namely pulsed plasma discharges. The developed method of TR-LAS was applied to measurements of the temporal evolution of density and kinetic temperature of argon metastable species during high-power impulse magnetron sputtering of titanium and titanium dioxide thin films.

  18. A multifactorial and integrative approach to impulsivity in neuropsychology: insights from the UPPS model of impulsivity.

    PubMed

    Rochat, Lucien; Billieux, Joël; Gagnon, Jean; Van der Linden, Martial

    2017-04-11

    Risky and excessive behaviors, such as aggressive and compulsive behaviors, are frequently described in patients with brain damage and have dramatic psychosocial consequences. Although there is strong evidence that impulsivity constitutes a key factor at play in these behaviors, the literature about impulsivity in neuropsychology is to date scarce. In addition, examining and understanding these problematic behaviors requires the assumption that impulsivity is a multidimensional construct. Consequently, this article aims at shedding light on frequent risky and excessive behaviors in patients with brain damage by focusing on a unified, comprehensive, and well-validated model, namely, the UPPS model of impulsivity. This model considers impulsivity as a multidimensional construct that includes four facets: urgency, (lack of) premeditation, (lack of) perseverance, and sensation seeking. Furthermore, we discuss the psychological mechanisms underlying the dimensions of impulsivity, as well as the laboratory tasks designed to assess each mechanism and their neural bases. We then present a scale specifically designed to assess these four dimensions of impulsivity in patients with brain damage and examine the data regarding this multidimensional approach to impulsivity in neuropsychology. This review supports the need to adopt a multifactorial and integrative approach toward impulsive behaviors, and the model presented provides a valuable rationale to disentangle the nature of brain systems and mechanisms underlying impulsive behaviors in patients with brain damage. It may also foster further relevant research in the field of impulsivity and improve assessment and rehabilitation of impulsive behaviors in clinical settings.

  19. Evidence for breathing modes in direct current, pulsed, and high power impulse magnetron sputtering plasmas

    SciTech Connect

    Yang, Yuchen; Zhou, Xue; Liu, Jason X.; Anders, André

    2016-01-18

    We present evidence for breathing modes in magnetron sputtering plasmas: periodic axial variations of plasma parameters with characteristic frequencies between 10 and 100 kHz. A set of azimuthally distributed probes shows synchronous oscillations of the floating potential. They appear most clearly when considering the intermediate current regime in which the direction of azimuthal spoke motion changes. Breathing oscillations were found to be superimposed on azimuthal spoke motion. Depending on pressure and current, one can also find a regime of chaotic fluctuations and one of stable discharges, the latter at high current. A pressure-current phase diagram for the different situations is proposed.

  20. Sweet taste liking is associated with impulsive behaviors in humans

    PubMed Central

    Weafer, Jessica; Burkhardt, Anne; de Wit, Harriet

    2014-01-01

    Evidence from both human and animal studies suggests that sensitivity to rewarding stimuli is positively associated with impulsive behaviors, including both impulsive decision making and inhibitory control. The current study examined associations between the hedonic value of a sweet taste and two forms of impulsivity (impulsive choice and impulsive action) in healthy young adults (N = 100). Participants completed a sweet taste test in which they rated their liking of various sweetness concentrations. Subjects also completed measures of impulsive choice (delay discounting), and impulsive action (go/no-go task). Subjects who discounted more steeply (i.e., greater impulsive choice) liked the high sweetness concentration solutions more. By contrast, sweet liking was not related to impulsive action. These findings indicate that impulsive choice may be associated with heightened sensitivity to the hedonic value of a rewarding stimulus, and that these constructs might share common underlying neurobiological mechanisms. PMID:24987343

  1. An ionization region model of the reactive Ar/O2 high power impulse magnetron sputtering discharge

    NASA Astrophysics Data System (ADS)

    Gudmundsson, J. T.; Lundin, D.; Brenning, N.; Raadu, M. A.; Huo, Chunqing; Minea, T. M.

    2016-12-01

    A new reactive ionization region model (R-IRM) is developed to describe the reactive Ar/O2 high power impulse magnetron sputtering (HiPIMS) discharge with a titanium target. It is then applied to study the temporal behavior of the discharge plasma parameters such as electron density, the neutral and ion composition, the ionization fraction of the sputtered vapor, the oxygen dissociation fraction, and the composition of the discharge current. We study and compare the discharge properties when the discharge is operated in the two well established operating modes, the metal mode and the poisoned mode. Experimentally, it is found that in the metal mode the discharge current waveform displays a typical non-reactive evolution, while in the poisoned mode the discharge current waveform becomes distinctly triangular and the current increases significantly. Using the R-IRM we explore the current increase and find that when the discharge is operated in the metal mode Ar+ and Ti+ -ions contribute most significantly (roughly equal amounts) to the discharge current while in the poisoned mode the Ar+ -ions contribute most significantly to the discharge current and the contribution of O+ -ions, Ti+ -ions, and secondary electron emission is much smaller. Furthermore, we find that recycling of atoms coming from the target, that are subsequently ionized, is required for the current generation in both modes of operation. From the R-IRM results it is found that in the metal mode self-sputter recycling dominates and in the poisoned mode working gas recycling dominates. We also show that working gas recycling can lead to very high discharge currents but never to a runaway. It is concluded that the dominating type of recycling determines the discharge current waveform.

  2. Perspective: Is there a hysteresis during reactive High Power Impulse Magnetron Sputtering (R-HiPIMS)?

    NASA Astrophysics Data System (ADS)

    Strijckmans, K.; Moens, F.; Depla, D.

    2017-02-01

    This paper discusses a few mechanisms that can assist to answer the title question. The initial approach is to use an established model for DC magnetron sputter deposition, i.e., RSD2013. Based on this model, the impact on the hysteresis behaviour of some typical HiPIMS conditions is investigated. From this first study, it becomes clear that the probability to observe hysteresis is much lower as compared to DC magnetron sputtering. The high current pulses cannot explain the hysteresis reduction. Total pressure and material choice make the abrupt changes less pronounced, but the implantation of ionized metal atoms that return to the target seems to be the major cause. To further substantiate these results, the analytical reactive sputtering model is coupled with a published global plasma model. The effect of metal ion implantation is confirmed. Another suggested mechanism, i.e., gas rarefaction, can be ruled out to explain the hysteresis reduction. But perhaps the major conclusion is that at present, there are too little experimental data available to make fully sound conclusions.

  3. Three-Dimensional ISAR Imaging Method for High-Speed Targets in Short-Range Using Impulse Radar Based on SIMO Array

    PubMed Central

    Zhou, Xinpeng; Wei, Guohua; Wu, Siliang; Wang, Dawei

    2016-01-01

    This paper proposes a three-dimensional inverse synthetic aperture radar (ISAR) imaging method for high-speed targets in short-range using an impulse radar. According to the requirements for high-speed target measurement in short-range, this paper establishes the single-input multiple-output (SIMO) antenna array, and further proposes a missile motion parameter estimation method based on impulse radar. By analyzing the motion geometry relationship of the warhead scattering center after translational compensation, this paper derives the receiving antenna position and the time delay after translational compensation, and thus overcomes the shortcomings of conventional translational compensation methods. By analyzing the motion characteristics of the missile, this paper estimates the missile’s rotation angle and the rotation matrix by establishing a new coordinate system. Simulation results validate the performance of the proposed algorithm. PMID:26978372

  4. Three-Dimensional ISAR Imaging Method for High-Speed Targets in Short-Range Using Impulse Radar Based on SIMO Array.

    PubMed

    Zhou, Xinpeng; Wei, Guohua; Wu, Siliang; Wang, Dawei

    2016-03-11

    This paper proposes a three-dimensional inverse synthetic aperture radar (ISAR) imaging method for high-speed targets in short-range using an impulse radar. According to the requirements for high-speed target measurement in short-range, this paper establishes the single-input multiple-output (SIMO) antenna array, and further proposes a missile motion parameter estimation method based on impulse radar. By analyzing the motion geometry relationship of the warhead scattering center after translational compensation, this paper derives the receiving antenna position and the time delay after translational compensation, and thus overcomes the shortcomings of conventional translational compensation methods. By analyzing the motion characteristics of the missile, this paper estimates the missile's rotation angle and the rotation matrix by establishing a new coordinate system. Simulation results validate the performance of the proposed algorithm.

  5. Relative effects of social self-control, sensation seeking, and impulsivity on future cigarette use in a sample of high-risk adolescents.

    PubMed

    Pokhrel, Pallav; Sussman, Steve; Stacy, Alan

    2014-03-01

    We used confirmatory factor analysis to compare convergence/divergence across self-report measures of social self-control, sensation seeking, and impulsivity in a sample of high-risk adolescents. In addition, we tested baseline social self-control as a predictor of cigarette use one year later, controlling for baseline cigarette use, impulsivity/sensation seeking, and demographic variables. Data were collected in 2004-2005 from 821 adolescents (M age = 16.3; SD = 1.36) enrolled in 14 continuation high schools in Southern California. Of the baseline sample, 566 students participated in a follow-up survey one year later. Results indicated that social self-control represents a unique dimension of self-control and is a salient predictor of future cigarette use.

  6. Relative Effects of Social Self-Control, Sensation Seeking, and Impulsivity on Future Cigarette Use in a Sample of High-Risk Adolescents

    PubMed Central

    Pokhrel, Pallav; Sussman, Steve; Stacy, Alan

    2016-01-01

    We used confirmatory factor analysis to compare convergence/divergence across self-report measures of social self-control, sensation seeking, and impulsivity in a sample of high-risk adolescents. In addition, we tested baseline social self-control as a predictor of cigarette use one year later, controlling for baseline cigarette use, impulsivity/sensation seeking, and demographic. variables. Data were collected in 2004–2005 from 821 adolescents (M age = 16.3; SD = 1.36) enrolled in 14 continuation high schools in Southern California. Of the baseline sample, 566 students participated in a follow-up survey one year later. Results indicated that social self-control represents a unique dimension of self-control and is a salient predictor of future cigarette use. PMID:24093522

  7. Behavioral assessment of impulsivity in pathological gamblers with and without substance use disorder histories versus healthy controls.

    PubMed

    Ledgerwood, David M; Alessi, Sheila M; Phoenix, Natalie; Petry, Nancy M

    2009-11-01

    Pathological gamblers (PGs) may have high levels of impulsivity, and a correlation between substance use disorders (SUDs) and impulsivity is well established. However, only a handful of studies have attempted to assess impulsivity and other impulse-spectrum traits (e.g., sensation seeking) using a variety of behavioral and self-report measures in PGs and few examined the independent impact of SUDs. We compared 30 PGs without SUD histories, 31 PGs with SUD histories and 40 control participants on self-reported impulsivity, delayed discounting, attention/memory, response inhibition, risk taking, sensation seeking and distress tolerance measures. PGs, regardless of SUD history, discounted delayed rewards at greater rates than controls. PGs also reported acting on the spur of the moment, experienced trouble planning and thinking carefully, and noted greater attention difficulties than controls. PGs with SUD took greater risks on a risk-taking task than did PGs without SUD histories, but the two groups did not differ on any other measures of impulsivity. We conclude that PGs are more impulsive than non-problem gamblers in fairly specific ways, but PGs with and without SUD histories differ on few measures. More research should focus on specific ways in which PGs exhibit impulsivity to better address impulsive behaviors in treatment.

  8. The use of segmented cathodes to determine the spoke current density distribution in high power impulse magnetron sputtering plasmas

    SciTech Connect

    Poolcharuansin, Phitsanu; Estrin, Francis Lockwood; Bradley, James W.

    2015-04-28

    The localized target current density associated with quasi-periodic ionization zones (spokes) has been measured in a high power impulse magnetron sputtering (HiPIMS) discharge using an array of azimuthally separated and electrical isolated probes incorporated into a circular aluminum target. For a particular range of operating conditions (pulse energies up to 2.2 J and argon pressures from 0.2 to 1.9 Pa), strong oscillations in the probe current density are seen with amplitudes up to 52% above a base value. These perturbations, identified as spokes, travel around the discharge above the target in the E×B direction. Using phase information from the angularly separated probes, the spoke drift speeds, angular frequencies, and mode number have been determined. Generally, at low HiPIMS pulse energies E{sub p} < 0.8 J, spokes appear to be chaotic in nature (with random arrival times), however as E{sub p} increases, coherent spokes are observed with velocities between 6.5 and 10 km s{sup −1} and mode numbers m = 3 or above. At E{sub p} > 1.8 J, the plasma becomes spoke-free. The boundaries between chaotic, coherent, and no-spoke regions are weakly dependent on pressure. During each HiPIMS pulse, the spoke velocities increase by about 50%. Such an observation is explained by considering spoke velocities to be determined by the critical ionization velocity, which changes as the plasma composition changes during the pulse. From the shape of individual current density oscillations, it appears that the leading edge of the spoke is associated with a slow increase in local current density to the target and the rear with a more rapid decrease. The measurements show that the discharge current density associated with individual spokes is broadly spread over a wide region of the target.

  9. Process stabilization by peak current regulation in reactive high-power impulse magnetron sputtering of hafnium nitride

    NASA Astrophysics Data System (ADS)

    Shimizu, T.; Villamayor, M.; Lundin, D.; Helmersson, U.

    2016-02-01

    A simple and cost effective approach to stabilize the sputtering process in the transition zone during reactive high-power impulse magnetron sputtering (HiPIMS) is proposed. The method is based on real-time monitoring and control of the discharge current waveforms. To stabilize the process conditions at a given set point, a feedback control system was implemented that automatically regulates the pulse frequency, and thereby the average sputtering power, to maintain a constant maximum discharge current. In the present study, the variation of the pulse current waveforms over a wide range of reactive gas flows and pulse frequencies during a reactive HiPIMS process of Hf-N in an Ar-N2 atmosphere illustrates that the discharge current waveform is a an excellent indicator of the process conditions. Activating the reactive HiPIMS peak current regulation, stable process conditions were maintained when varying the N2 flow from 2.1 to 3.5 sccm by an automatic adjustment of the pulse frequency from 600 Hz to 1150 Hz and consequently an increase of the average power from 110 to 270 W. Hf-N films deposited using peak current regulation exhibited a stable stoichiometry, a nearly constant power-normalized deposition rate, and a polycrystalline cubic phase Hf-N with (1 1 1)-preferred orientation over the entire reactive gas flow range investigated. The physical reasons for the change in the current pulse waveform for different process conditions are discussed in some detail.

  10. Process- and optoelectronic-control of NiOx thin films deposited by reactive high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Keraudy, Julien; Delfour-Peyrethon, Brice; Ferrec, Axel; Garcia Molleja, Javier; Richard-Plouet, Mireille; Payen, Christophe; Hamon, Jonathan; Corraze, Benoît; Goullet, Antoine; Jouan, Pierre-Yves

    2017-05-01

    In this contribution, based on the analyses of the discharge behavior as well as final properties of the deposited Ni-O films during reactive high power impulse magnetron sputtering discharge, we have demonstrated that monitoring the oxygen flow rate leads to 4 different regimes of discharge. Tuning the oxygen partial pressure allows deposition of a large range of chemical compositions from pure nickel to nickel-deficient NiOx (x > 1) in the poisoned mode. Investigation of the plasma dynamics by time-resolved optical emission spectroscopy suggests that the discharge behavior in the poisoned mode principally comes from the higher contribution of both oxygen and argon ions in the total ionic current, leading to a change in the ion induced secondary electron emission coefficient. Additionally, material characterizations have revealed that optoelectronic properties of NiOx films can be easily tuned by adjusting the O/Ni ratio, which is influenced by the change of the oxygen flow rate. Stoichiometric NiO films (O/Ni ratio ˜ 1) are transparent in the visible range with a transmittance ˜80% and insulating as expected with an electrical resistivity ˜106 Ω cm. On the other hand, increasing the O/Ni > 1 leads to the deposition of more conductive coating (ρ ˜ 10 Ω cm) films with a lower transmittance ˜ 50%. These optoelectronic evolutions are accompanied by a band-gap narrowing 3.65 to 3.37 eV originating from the introduction of acceptor states between the Fermi level and the valence band maximum. In addition, our analysis has demonstrated that nickel vacancies are homogeneously distributed over the film thickness, explaining the p-type of the films.

  11. Influence of high power impulse magnetron sputtering plasma ionization on the microstructure of TiN thin films

    SciTech Connect

    Ehiasarian, A. P.; Vetushka, A.; Gonzalvo, Y. Aranda; Safran, G.; Szekely, L.; Barna, P. B.

    2011-05-15

    HIPIMS (High Power Impulse Magnetron Sputtering) discharge is a new PVD technology for the deposition of high-quality thin films. The deposition flux contains a high degree of metal ionization and nitrogen dissociation. The microstructure of HIPIMS-deposited nitride films is denser compared to conventional sputter technologies. However, the mechanisms acting on the microstructure, texture and properties have not been discussed in detail so far. In this study, the growth of TiN by HIPIMS of Ti in mixed Ar and N{sub 2} atmosphere has been investigated. Varying degrees of metal ionization and nitrogen dissociation were produced by increasing the peak discharge current (I{sub d}) from 5 to 30 A. The average power was maintained constant by adjusting the frequency. Mass spectrometry measurements of the deposition flux revealed a high content of ionized film-forming species, such as Ti{sup 1+}, Ti{sup 2+} and atomic nitrogen N{sup 1+}. Ti{sup 1+} ions with energies up to 50 eV were detected during the pulse with reducing energy in the pulse-off times. Langmuir probe measurements showed that the peak plasma density during the pulse was 3 x 10{sup 16} m{sup -3}. Plasma density, and ion flux ratios of N{sup 1+}: N{sub 2}{sup 1+} and Ti{sup 1+}: Ti{sup 0} increased linearly with peak current. The ratios exceeded 1 at 30 A. TiN films deposited by HIPIMS were analyzed by X-ray diffraction, and transmission electron microscopy. At high I{sub d}, N{sup 1+}: N{sub 2}{sup 1+} > 1 and Ti{sup 1+}: Ti{sup 0} > 1 were produced; a strong 002 texture was present and column boundaries in the films were atomically tight. As I{sub d} reduced and N{sup 1+}: N{sub 2}{sup 1+} and Ti{sup 1+}: Ti{sup 0} dropped below 1, the film texture switched to strong 111 with a dense structure. At very low I{sub d}, porosity between columns developed. The effects of the significant activation of the deposition flux observed in the HIPIMS discharge on the film texture, microstructure, morphology and

  12. Activity and impulsive action are controlled by different genetic and environmental factors.

    PubMed

    Loos, M; van der Sluis, S; Bochdanovits, Z; van Zutphen, I J; Pattij, T; Stiedl, O; Smit, A B; Spijker, S

    2009-11-01

    Both impulsivity in operant tasks and locomotor activity in a novel open field are known to predict the development of addiction-related behavior in rodents. In this study, we investigated to what extent impulsivity in the five-choice serial reaction time task and various measures of novelty exploration are controlled by shared genetic and environmental factors in 12 different inbred mouse strains. No genetic correlation was observed between the level of impulsivity and levels of activity, a low correlation was observed with traditional measures of anxiety-like behavior (impulsive strains tend to be less anxious) and a highly significant correlation was found between impulsivity and specific aspects of movement. Furthermore, we found that impulsivity and all measures of novelty exploration were under control of different environmental factors. Interestingly, in the dorsal medial prefrontal cortex, a brain region involved in impulsivity and activity in novelty exploration tests; these behavioral measures correlated with the expression of different genes (respectively, Frzb, Snx5, BC056474 and the previously identified Glo1). Taken together, our study shows that impulsivity and activity in novelty exploration tests are genetically and environmentally distinct, suggesting that mouse models of these behaviors provide complementary insights into the development of substance abuse disorder.

  13. Impulsivity and the Modular Organization of Resting-State Neural Networks

    PubMed Central

    Davis, F. Caroline; Knodt, Annchen R.; Sporns, Olaf; Lahey, Benjamin B.; Zald, David H.; Brigidi, Bart D.; Hariri, Ahmad R.

    2013-01-01

    Impulsivity is a complex trait associated with a range of maladaptive behaviors, including many forms of psychopathology. Previous research has implicated multiple neural circuits and neurotransmitter systems in impulsive behavior, but the relationship between impulsivity and organization of whole-brain networks has not yet been explored. Using graph theory analyses, we characterized the relationship between impulsivity and the functional segregation (“modularity”) of the whole-brain network architecture derived from resting-state functional magnetic resonance imaging (fMRI) data. These analyses revealed remarkable differences in network organization across the impulsivity spectrum. Specifically, in highly impulsive individuals, regulatory structures including medial and lateral regions of the prefrontal cortex were isolated from subcortical structures associated with appetitive drive, whereas these brain areas clustered together within the same module in less impulsive individuals. Further exploration of the modular organization of whole-brain networks revealed novel shifts in the functional connectivity between visual, sensorimotor, cortical, and subcortical structures across the impulsivity spectrum. The current findings highlight the utility of graph theory analyses of resting-state fMRI data in furthering our understanding of the neurobiological architecture of complex behaviors. PMID:22645253

  14. Life Event Stress and Binge Eating Among Adolescents: The Roles of Early Maladaptive Schemas and Impulsivity.

    PubMed

    Zhu, Hong; Luo, Xingwei; Cai, Taisheng; He, Jinbo; Lu, Yao; Wu, Siyao

    2016-10-01

    This study examined the relationships between life event stress, early maladaptive schemas, impulsivity and binge eating among adolescents and investigated the effects of early maladaptive schemas and impulsivity on the relationship between life event stress and binge eating. Specifically, we examined a moderated mediation model in which early maladaptive schemas mediated this relationship and impulsivity moderated the mediation effect. Life event stress, early maladaptive schemas, impulsivity and binge eating were investigated in a sample of 2172 seventh-, eighth- and tenth-grade middle and high school students (mean age = 14.55 years, standard deviation = 1.29). The results indicated that adolescents with greater life event stress, more early maladaptive schemas and higher levels of impulsivity displayed more severe binge eating. In addition, early maladaptive schemas mediated the relationship between life event stress and binge eating, while impulsivity moderated this relationship. Furthermore, impulsivity also moderated the mediation effect of early maladaptive schemas; as impulsivity levels increased, the strength of the association between life event stress and early maladaptive schemas increased. This study illustrates the importance of understanding individual differences and their effects on the relationship between life event stress and binge eating. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  15. Anatomy of a SAR impulse response.

    SciTech Connect

    Doerry, Armin Walter

    2007-08-01

    A principal measure of Synthetic Aperture Radar (SAR) image quality is the manifestation in the SAR image of a spatial impulse, that is, the SAR's Impulse Response (IPR). IPR requirements direct certain design decisions in a SAR. Anomalies in the IPR can point to specific anomalous behavior in the radar's hardware and/or software.

  16. Impulsivity and personality variables in adolescents with eating disorders.

    PubMed

    Boisseau, Christina L; Thompson-Brenner, Heather; Eddy, Kamryn T; Satir, Dana A

    2009-04-01

    Impulsivity among individuals with eating disorders (EDs) is associated with severe comorbidities and poor treatment outcome. However, research investigating the construct of impulsivity in EDs is limited. The objectives of the present study were to characterize multiple dimensions of impulsivity in adolescents with EDs; determine if differences in impulsivity were associated with ED diagnosis and/or broader personality traits; and explore the relationship between impulsivity and etiologically significant variables. Experienced clinicians from a practice-research network provided data on ED symptoms, impulsive characteristics, personality pathology, The Diagnostic and Statistical Manual of Mental Disorders comorbidity, and family and developmental history for 120 adolescent patients with EDs. Three distinct types of impulsivity were identified: general, acting out, and aggressive/destructive. The impulsivity types showed specific relationships to ED diagnosis, broader personality factors, individual histories of adverse (traumatic) events, and family histories of externalizing disorders, supporting the importance of taking, assessing, and addressing impulsivity in ED research and treatment.

  17. Further evidence of the heterogeneous nature of impulsivity.

    PubMed

    Caswell, Amy J; Bond, Rod; Duka, Theodora; Morgan, Michael J

    2015-04-01

    'Impulsivity' refers to a range of behaviours including preference for immediate reward (temporal-impulsivity) and the tendency to make premature decisions (reflection-impulsivity) and responses (motor-impulsivity). The current study aimed to examine how different behavioural and self-report measurements of impulsivity can be categorised into distinct subtypes. Exploratory factor analysis using full information maximum likelihood was conducted on 10 behavioural and 1 self-report measure of impulsivity. Four factors of impulsivity were indicated, with Factor 1 having a high loading of the Stop Signal Task, which measures motor-impulsivity, factor 2 representing reflection-impulsivity with loadings of the Information Sampling Task and Matching Familiar Figures Task, factor 3 representing the Immediate Memory Task, and finally factor 4 which represents the Delay Discounting Questionnaire and The Monetary Choice Questionnaire, measurements of temporal-impulsivity. These findings indicated that impulsivity is not a unitary construct, and instead represents a series of independent subtypes. There was evidence of a distinct reflection-impulsivity factor, providing the first factor analysis support for this subtype. There was also support for additional factors of motor- and temporal-impulsivity. The present findings indicated that a number of currently accepted tasks cannot be considered as indexing motor- and temporal-impulsivity suggesting that additional characterisations of impulsivity may be required.

  18. Reliability and Validity of Measures of Impulsive Choice and Impulsive Action in Smokers Trying to Quit

    PubMed Central

    McCarthy, Danielle E.; Bold, Krysten W.; Minami, Haruka; Yeh, Vivian M.; Rutten, Emily; Nadkarni, Shruti G.; Chapman, Gretchen B.

    2016-01-01

    Cross-sectional research suggests that smokers are more impulsive than are non-smokers, but few studies have examined relations between impulsiveness and later success in quitting smoking. The purpose of this study was to investigate the reliability and predictive validity of facets of impulsiveness in adult smokers trying to quit. Baseline behavioral measures of impulsive choice (assessed with a delay discounting task) and impulsive action (assessed with a measure of behavioral disinhibition) were used as predictors of smoking cessation success over 12 weeks. The sample included 116 adult (18 years old or older) daily smokers from central New Jersey. Impulsive choice, impulsive action, and self-reported impulsiveness were not significantly related to one another at baseline. Impulsive choice had high test-retest reliability from pre- to post-quit, whereas impulsive action was less stable. Test-retest reliability from pre-quit to three weeks post-quit was moderated by achievement of seven-day abstinence. Baseline impulsive action was significantly negatively related to quitting for at least one day in the first two weeks of a quit attempt and of prolonged abstinence (no relapse over the next 10 weeks). Baseline impulsive choice was robustly associated with biochemically verified seven-day point-prevalence abstinence 12 weeks post-quit, such that those with lower delay discounting were more likely to achieve abstinence. Facets of impulsiveness appear to function largely independently in adult smokers, as indicated by their lack of inter-correlation, differential stability, and differential relations with abstinence. Impulsive action may impede initial quitting, whereas impulsive choice may be an obstacle to maintaining lasting abstinence. PMID:26751623

  19. Serotonergic modulation of ‘waiting impulsivity' is mediated by the impulsivity phenotype in humans

    PubMed Central

    Neufang, S; Akhrif, A; Herrmann, C G; Drepper, C; Homola, G A; Nowak, J; Waider, J; Schmitt, A G; Lesch, K-P; Romanos, M

    2016-01-01

    In rodents, the five-choice serial reaction time task (5-CSRTT) has been established as a reliable measure of waiting impulsivity being defined as the ability to regulate a response in anticipation of reinforcement. Key brain structures are the nucleus accumbens (NAcc) and prefrontal regions (for example, pre- and infralimbic cortex), which are, together with other transmitters, modulated by serotonin. In this functional magnetic resonance imaging study, we examined 103 healthy males while performing the 5-CSRTT measuring brain activation in humans by means of a paradigm that has been widely applied in rodents. Subjects were genotyped for the tryptophan hydroxylase-2 (TPH2; G-703T; rs4570625) variant, an enzyme specific for brain serotonin synthesis. We addressed neural activation patterns of waiting impulsivity and the interaction between the NAcc and the ventromedial prefrontal cortex (vmPFC) using dynamic causal modeling. Genetic influence was examined via interaction analyses between the TPH2 genotype (GG homozygotes vs T allele carriers) and the degree of impulsivity as measured by the 5-CSRTT. We found that the driving input of the vmPFC was reduced in highly impulsive T allele carriers (reflecting a reduced top-down control) in combination with an enhanced response in the NAcc after correct target processing (reflecting an augmented response to monetary reward). Taken together, we found a high overlap of our findings with reports from animal studies in regard to the underlying cognitive processes, the brain regions associated with waiting impulsivity and the neural interplay between the NAcc and vmPFC. Therefore, we conclude that the 5-CSRTT is a promising tool for translational studies. PMID:27824354

  20. Impulse control disorders in adult psychiatric inpatients.

    PubMed

    Grant, Jon E; Levine, Laura; Kim, Daniel; Potenza, Marc N

    2005-11-01

    The authors' goal was to examine the prevalence of impulse control disorders in psychiatric inpatients. They used the Minnesota Impulsive Disorders Interview, a semistructured clinical interview assessing pathological gambling, trichotillomania, kleptomania, pyromania, intermittent explosive disorder, compulsive buying, and compulsive sexual behavior, to screen 204 consecutively admitted psychiatric inpatients. One hundred twelve of the inpatients were women (54.9%), and the mean age of the 204 inpatients was 40.5 years (SD=13.2, range=18-83). Patients whose screen was positive for an impulse control disorder were evaluated with structured clinical interviews. Sixty-three patients (30.9%) were diagnosed with at least one current impulse control disorder. The most common impulse control disorders were compulsive buying (N=19 [9.3%]), kleptomania (N=16 [7.8%]), and pathological gambling (N=14 [6.9%]). Patients with and without co-occurring impulse control disorders did not differ significantly from each other on demographic measures or number or type of psychiatric diagnoses other than impulse control disorders. Impulse control disorders appear common among psychiatric inpatients. Additional, larger studies are needed to examine the prevalence of impulse control disorders in the general population and specific psychiatric groups.

  1. Conversion of Impulse Voltage Generator Into Steep Wave Impulse Test-Equipment

    NASA Astrophysics Data System (ADS)

    Khan, Mohammed Zaid; Tanwar, Surender Singh; Dayama, Ravindra; Choudhary, Rahul Raj; Mangal, Ravindra

    This paper demonstrates the alternative measures to generate the Steep wave impulse by using Impulse Voltage Generator (IVG) for high voltage testing of porcelain insulators. The modification of IVG by incorporating compensation of resistor, inductor, and capacitor has been achieved and further performance of the modified system has been analyzed by applying the generated lightning impulse and analyzing the electrical characteristics of impulse waves under standard lightning and fast rise multiple lightning waveform to determine the effect to improve rise time. The advantageous results have been received and being reported such as increase in overshoot compensation, increase in capacitive and inductive load ranges. Such further reduces the duration of oscillations of standard impulse voltages. The reduction in oscillation duration of steep front impulse voltages may be utilized in up gradation of Impulse Voltage Generator System. Stray capacitance could further be added in order to get the minimized difference of measurement between simulation and the field establishment.

  2. Micropower impulse radar

    SciTech Connect

    Azevedo, S.; McEwan, T.E.

    1996-01-01

    Invented and developed at Lawrence Livermore National Laboratory is an inexpensive and highly sensitive, low-power radar system that produces and samples extremely short pulses of energy at the rate of 2 million per second. Called micropower impulse radar (MIR), it can detect objects at a greater variety of distances with greater sensitivity than conventional radar. Its origins in the Laboratory`s Laser Directorate stem from Nova`s transient digitizer. The MIR`s extraordinary range of applications include security, search and rescue, life support, nondestructive evaluation, and transportation.

  3. Production of high specific activity silicon-32

    SciTech Connect

    Phillips, D.R.; Brzezinski, M.A.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development Project (LDRD) at Los Alamos National Laboratory (LANL). There were two primary objectives for the work performed under this project. The first was to take advantage of capabilities and facilities at Los Alamos to produce the radionuclide {sup 32}Si in unusually high specific activity. The second was to combine the radioanalytical expertise at Los Alamos with the expertise at the University of California to develop methods for the application of {sup 32}Si in biological oceanographic research related to global climate modeling. The first objective was met by developing targetry for proton spallation production of {sup 32}Si in KCl targets and chemistry for its recovery in very high specific activity. The second objective was met by developing a validated field-useable, radioanalytical technique, based upon gas-flow proportional counting, to measure the dynamics of silicon uptake by naturally occurring diatoms.

  4. Development of High Specific Strength Envelope Materials

    NASA Astrophysics Data System (ADS)

    Komatsu, Keiji; Sano, Masa-Aki; Kakuta, Yoshiaki

    Progress in materials technology has produced a much more durable synthetic fabric envelope for the non-rigid airship. Flexible materials are required to form airship envelopes, ballonets, load curtains, gas bags and covering rigid structures. Polybenzoxazole fiber (Zylon) and polyalirate fiber (Vectran) show high specific tensile strength, so that we developed membrane using these high specific tensile strength fibers as a load carrier. The main material developed is a Zylon or Vectran load carrier sealed internally with a polyurethane bonded inner gas retention film (EVOH). The external surface provides weather protecting with, for instance, a titanium oxide integrated polyurethane or Tedlar film. The mechanical test results show that tensile strength 1,000 N/cm is attained with weight less than 230g/m2. In addition to the mechanical properties, temperature dependence of the joint strength and solar absorptivity and emissivity of the surface are measured. 

  5. A Twin Study of ADHD Symptoms in Early Adolescence: Hyperactivity-Impulsivity and Inattentiveness Show Substantial Genetic Overlap but Also Genetic Specificity

    ERIC Educational Resources Information Center

    Greven, Corina U.; Rijsdijk, Fruhling V.; Plomin, Robert

    2011-01-01

    A previous paper in this journal revealed substantial genetic overlap between the ADHD dimensions of hyperactivity-impulsivity and inattentiveness in a sample of 8-year old twins drawn from a UK-representative population sample. Four years later, when the twins were 12 years old, more than 5,500 pairs drawn from the same sample were rated again on…

  6. A Twin Study of ADHD Symptoms in Early Adolescence: Hyperactivity-Impulsivity and Inattentiveness Show Substantial Genetic Overlap but Also Genetic Specificity

    ERIC Educational Resources Information Center

    Greven, Corina U.; Rijsdijk, Fruhling V.; Plomin, Robert

    2011-01-01

    A previous paper in this journal revealed substantial genetic overlap between the ADHD dimensions of hyperactivity-impulsivity and inattentiveness in a sample of 8-year old twins drawn from a UK-representative population sample. Four years later, when the twins were 12 years old, more than 5,500 pairs drawn from the same sample were rated again on…

  7. Research on High-Specific-Heat Dielectrics

    DTIC Science & Technology

    1990-01-31

    wellp as related thermodynamic properties , we infer the following conclusions: 1. The exceptionally high C peaks for ZnCr204 andp 2 CdCr204 in the 2...which determine the electric, magnetic, and thermodynamic properties of the system. In addition, we have found from this microscopic analysis that... properties of this lattice will therefore be dominated by the properties of the cluster. The 3 thermodynamic properties such as the energy, the specific

  8. SiNx coatings deposited by reactive high power impulse magnetron sputtering: Process parameters influencing the residual coating stress

    NASA Astrophysics Data System (ADS)

    Schmidt, S.; Hänninen, T.; Wissting, J.; Hultman, L.; Goebbels, N.; Santana, A.; Tobler, M.; Högberg, H.

    2017-05-01

    The residual coating stress and its control is of key importance for the performance and reliability of silicon nitride (SiNx) coatings for biomedical applications. This study explores the most important deposition process parameters to tailor the residual coating stress and hence improve the adhesion of SiNx coatings deposited by reactive high power impulse magnetron sputtering (rHiPIMS). Reactive sputter deposition and plasma characterization were conducted in an industrial deposition chamber equipped with pure Si targets in N2/Ar ambient. Reactive HiPIMS processes using N2-to-Ar flow ratios of 0 and 0.28-0.3 were studied with time averaged positive ion mass spectrometry. The coatings were deposited to thicknesses of 2 μm on Si(001) and to 5 μm on polished CoCrMo disks. The residual stress of the X-ray amorphous coatings was determined from the curvature of the Si substrates as obtained by X-ray diffraction. The coatings were further characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, and nanoindentation in order to study their elemental composition, morphology, and hardness, respectively. The adhesion of the 5 μm thick coatings deposited on CoCrMo disks was assessed using the Rockwell C test. The deposition of SiNx coatings by rHiPIMS using N2-to-Ar flow ratios of 0.28 yield dense and hard SiNx coatings with Si/N ratios <1. The compressive residual stress of up to 2.1 GPa can be reduced to 0.2 GPa using a comparatively high deposition pressure of 600 mPa, substrate temperatures below 200 °C, low pulse energies of <2.5 Ws, and moderate negative bias voltages of up to 100 V. These process parameters resulted in excellent coating adhesion (ISO 0, HF1) and a low surface roughness of 14 nm for coatings deposited on CoCrMo.

  9. Campground marketing - the impulse camper

    Treesearch

    Wilbur F. LaPage; Dale P. Ragain

    1972-01-01

    Impulse or unplanned campground visits may account for one-fourth to one-half of all camping activity. The concepts of impulse travel and impulse camping appear to be potentially useful extensions of the broader concept of impulse purchasing, which has become an important influence in retail marketing. Impulse campers may also be impulse buyers; they were found to...

  10. Impulsive phenomena, the impulsive character (der Triebhafte Charakter) and DSM personality disorders.

    PubMed

    Perry, J Christopher; Körner, Annett C

    2011-10-01

    Impulsive phenomena have frequently been associated with personality disorders, beginning with Reich's description of the impulsive-character (Reich, 1925/1975). However, questions remain regarding the cooccurrence of a wide variety of impulsive phenomena and whether an underlying structure influences the differential association of impulses to individual personality disorders. Adults entering residential treatment for treatment-refractory disorders were interviewed about their lifetime histories of 33 impulse items, following independent diagnostic interviews. Factor analysis suggested 12 underlying dimensions of impulsive phenomena, explaining 68% of the variance. Borderline and antisocial PDs had the highest impulse scores, followed by self-defeating, narcissistic, depressive, and passive-aggressive PDs. Schizoid, avoidant, obsessive-compulsive, and dependent types were negatively associated with impulsive phenomena. Individuals with the highest impulse scores showed higher levels of borderline, antisocial and either self-defeating or passive-aggressive personality pathology, and were characterized by high Neuroticism and Openness and low Agreeableness on the NEO-FFI. Personality disorders and the NEO-FFI personality traits both predicted unique variance in impulsive phenomena, with the former predominating. Our findings bear striking similarities to Reich's (1925/1975) descriptions of the impulsive character.

  11. 5-HT(2A) and mGlu2 receptor binding levels are related to differences in impulsive behavior in the Roman Low- (RLA) and High- (RHA) avoidance rat strains.

    PubMed

    Klein, A B; Ultved, L; Adamsen, D; Santini, M A; Tobeña, A; Fernandez-Teruel, A; Flores, P; Moreno, M; Cardona, D; Knudsen, G M; Aznar, S; Mikkelsen, J D

    2014-03-28

    The Roman Low- and High-Avoidance rat strains (RLA-I vs RHA-I) have been bidirectionally selected and bred according to their performance in the two-way active avoidance response in the shuttle-box test. Numerous studies have reported a pronounced divergence in emotionality between the two rat strains including differences in novelty seeking, anxiety, stress coping, and susceptibility to addictive substances. However, the underlying molecular mechanisms behind these divergent phenotypes are not known. Here, we determined impulsivity using the 5-choice serial reaction time task and levels of serotonin transporter (SERT), 5-HT(2A) and 5-HT(1A) receptor binding using highly specific radioligands ((3)H-escitalopram, (3)H-MDL100907 and (3)H-WAY100635) and mGlu2/3 receptor binding ((3)H-LY341495) using receptor autoradiography in fronto-cortical sections from RLA-I (n=8) and RHA-I (n=8) male rats. In the more impulsive RHA-I rats, 5-HT(2A), 5-HT(1A) and SERT binding in the frontal cortex was significantly higher compared to RLA-I rats. In contrast, mGlu2/3 receptor binding was decreased by 40% in RHA-I rats compared to RLA-I rats. To differentiate between mGlu2 and mGlu3 receptor protein levels, these were further studied using western blotting, which showed non-detectable levels of mGlu2 receptor protein in RHA rats, while no differences were observed for mGlu3 receptor protein levels. Collectively, these data show general congenital differences in the serotonergic system and a pronounced difference in mGlu2 receptor protein levels. We suggest that the differences in the serotonergic system may mediate some of the phenotypic characteristics in this strain such as hyper-impulsivity and susceptibility to drug addiction.

  12. Association of ventral striatum monoamine oxidase-A binding and functional connectivity in antisocial personality disorder with high impulsivity: A positron emission tomography and functional magnetic resonance imaging study.

    PubMed

    Kolla, Nathan J; Dunlop, Katharine; Downar, Jonathan; Links, Paul; Bagby, R Michael; Wilson, Alan A; Houle, Sylvain; Rasquinha, Fawn; Simpson, Alexander I; Meyer, Jeffrey H

    2016-04-01

    Impulsivity is a core feature of antisocial personality disorder (ASPD) associated with abnormal brain function and neurochemical alterations. The ventral striatum (VS) is a key region of the neural circuitry mediating impulsive behavior, and low monoamine oxidase-A (MAO-A) level in the VS has shown a specific relationship to the impulsivity of ASPD. Because it is currently unknown whether phenotypic MAO-A markers can influence brain function in ASPD, we investigated VS MAO-A level and the functional connectivity (FC) of two seed regions, superior and inferior VS (VSs, VSi). Nineteen impulsive ASPD males underwent [(11)C] harmine positron emission tomography scanning to measure VS MAO-A VT, an index of MAO-A density, and resting-state functional magnetic resonance imaging that assessed the FC of bilateral seed regions in the VSi and VSs. Subjects also completed self-report impulsivity measures. Results revealed functional coupling of the VSs with bilateral dorsomedial prefrontal cortex (DMPFC) that was correlated with VS MAO-A VT (r=0.47, p=0.04), and functional coupling of the VSi with right hippocampus that was anti-correlated with VS MAO-A VT (r=-0.55, p=0.01). Additionally, VSs-DMPFC FC was negatively correlated with NEO Personality Inventory-Revised impulsivity (r=-0.49, p=0.03), as was VSi-hippocampus FC with Barratt Impulsiveness Scale-11 motor impulsiveness (r=-0.50, p=0.03). These preliminary results highlight an association of VS MAO-A level with the FC of striatal regions linked to impulsive behavior in ASPD and suggest that phenotype-based brain markers of ASPD have relevance to understanding brain function. Copyright © 2016 Elsevier B.V. and ECNP. All rights reserved.

  13. [Affective disorders and impulsivity].

    PubMed

    Belzeaux, R; Correard, N; Mazzola-Pomietto, P; Adida, M; Cermolacce, M; Azorin, J-M

    2014-12-01

    Impulsivity is a complex and important phenomenon in mood disorders. Impulse control disorders, as defined in DSM, are more frequent in mood disorders especially in Bipolar Disorder type I, and are associated with a more severe course of illness. Dimensional studies demonstrate that impulsivity is a core manifestation of bipolar disorder both as state- and trait-dependent markers in patients. Comorbid substance use disorders are often associated with a higher level of impulsivity whereas the relation between suicidal behaviors and higher impulsivity remains uncertain. Moreover, neuropsychological tests were used to study correlation between clinical impulsivity and laboratory measurements of impulsivity. Level of correlation remains weak and several explanations are proposed in the literature. Copyright © 2014 L’Encéphale. Published by Elsevier Masson SAS.. All rights reserved.

  14. Wp specific methylation of highly proliferated LCLs

    SciTech Connect

    Park, Jung-Hoon; Jeon, Jae-Pil; Shim, Sung-Mi; Nam, Hye-Young; Kim, Joon-Woo; Han, Bok-Ghee; Lee, Suman . E-mail: suman@cha.ac.kr

    2007-06-29

    The epigenetic regulation of viral genes may be important for the life cycle of EBV. We determined the methylation status of three viral promoters (Wp, Cp, Qp) from EBV B-lymphoblastoid cell lines (LCLs) by pyrosequencing. Our pyrosequencing data showed that the CpG region of Wp was methylated, but the others were not. Interestingly, Wp methylation was increased with proliferation of LCLs. Wp methylation was as high as 74.9% in late-passage LCLs, but 25.6% in early-passage LCLs. From two Burkitt's lymphoma cell lines, Wp specific hypermethylation was also found (>80%). Interestingly, the expression of EBNA2 gene which located directly next to Wp was associated with its methylation. Our data suggested that Wp specific methylation may be important for the indicator of the proliferation status of LCLs, and the epigenetic viral gene regulation of EBNA2 gene by Wp should be further defined possibly with other biological processes.

  15. Evolution of the plasma composition of a high power impulse magnetron sputtering system studied with a time-of-flight spectrometer

    SciTech Connect

    Oks, Efim; Anders, Andre

    2008-12-31

    The plasma of a high power impulse magnetron sputtering (HiPIMS) system has been investigated using a time-of-flight (TOF) spectrometer. The target materials included high sputter yield materials (Cu, Ag), transition metals (Nb, Cr, Ti), and carbon (graphite); the sputtering gases were argon, krypton and nitrogen, and two different target thicknesses were selected to consider the role of the magnetic field strength. Measurements for selected combinations of those parameters give quantitative information on the transition from gas-dominated to metal-dominated (self-sputtering) plasma, on the fractions of ion charge states, and in the case of molecular gases, on the fraction of atomic and molecular ions.

  16. Temporal Preparation, Response Inhibition and Impulsivity

    ERIC Educational Resources Information Center

    Correa, Angel; Trivino, Monica; Perez-Duenas, Carolina; Acosta, Alberto; Lupianez, Juan

    2010-01-01

    Temporal preparation and impulsivity involve overlapping neural structures (prefrontal cortex) and cognitive functions (response inhibition and time perception), however, their interrelations had not been investigated. We studied such interrelations by comparing the performance of groups with low vs. high non-clinical trait impulsivity during a…

  17. Temporal Preparation, Response Inhibition and Impulsivity

    ERIC Educational Resources Information Center

    Correa, Angel; Trivino, Monica; Perez-Duenas, Carolina; Acosta, Alberto; Lupianez, Juan

    2010-01-01

    Temporal preparation and impulsivity involve overlapping neural structures (prefrontal cortex) and cognitive functions (response inhibition and time perception), however, their interrelations had not been investigated. We studied such interrelations by comparing the performance of groups with low vs. high non-clinical trait impulsivity during a…

  18. Production Of High Specific Activity Copper-67

    DOEpatents

    Jamriska, Sr., David J.; Taylor, Wayne A.; Ott, Martin A.; Fowler, Malcolm; Heaton, Richard C.

    2003-10-28

    A process for the selective production and isolation of high specific activity Cu.sup.67 from proton-irradiated enriched Zn.sup.70 target comprises target fabrication, target irradiation with low energy (<25 MeV) protons, chemical separation of the Cu.sup.67 product from the target material and radioactive impurities of gallium, cobalt, iron, and stable aluminum via electrochemical methods or ion exchange using both anion and cation organic ion exchangers, chemical recovery of the enriched Zn.sup.70 target material, and fabrication of new targets for re-irradiation is disclosed.

  19. Production Of High Specific Activity Copper-67

    DOEpatents

    Jamriska, Sr., David J.; Taylor, Wayne A.; Ott, Martin A.; Fowler, Malcolm; Heaton, Richard C.

    2002-12-03

    A process for the selective production and isolation of high specific activity cu.sup.67 from proton-irradiated enriched Zn.sup.70 target comprises target fabrication, target irradiation with low energy (<25 MeV) protons, chemical separation of the Cu.sup.67 product from the target material and radioactive impurities of gallium, cobalt, iron, and stable aluminum via electrochemical methods or ion exchange using both anion and cation organic ion exchangers, chemical recovery of the enriched Zn.sup.70 target material, and fabrication of new targets for re-irradiation is disclosed.

  20. Specific Contributions of Age of Onset, Callous-Unemotional Traits and Impulsivity to Reactive and Proactive Aggression in Youths with Conduct Disorders.

    PubMed

    Urben, Sébastien; Habersaat, Stéphanie; Pihet, Sandrine; Suter, Maya; de Ridder, Jill; Stéphan, Philippe

    2017-03-27

    Youths with conduct disorders (CD) are particularly studied for their violent and aggressive behaviors. Many researchers considered aggressive behaviors as being either reactive or proactive. Moreover, factors such as age of CD onset, impulsivity, and callous-unemotional traits, separately, have been related to these different types of aggressive behaviors. However, very few studies addressed the combined contribution of these three factors on proactive and reactive aggression. This question was tested in a sample composed of 43 male adolescents with CD. A single regression analysis including all predictors and outcomes, using Bayesian statistics, was computed. Results indicated that impulsivity was related to reactive aggression, while CU traits were related to proactive aggression. These results suggest first, an important heterogeneity among youth with CD, probably leading to different trajectories and, second, that youths with callous-unemotional traits should receive special attention and care as they are more at risk for proactive aggression.

  1. High specific energy, high capacity nickel-hydrogen cell design

    NASA Technical Reports Server (NTRS)

    Wheeler, James R.

    1993-01-01

    A 3.5 inch rabbit-ear-terminal nickel-hydrogen cell has been designed and tested to deliver high capacity at a C/1.5 discharge rate. Its specific energy yield of 60.6 wh/kg is believed to be the highest yet achieved in a slurry-process nickel-hydrogen cell, and its 10 C capacity of 113.9 AH the highest capacity yet made at a discharge rate this high in the 3.5 inch diameter size. The cell also demonstrated a pulse capability of 180 amps for 20 seconds. Specific cell parameters, performance, and future test plans are described.

  2. Dependence of the specific features of two PAPVD methods: Impulse Plasma Deposition (IPD) and Pulsed Magnetron Sputtering (PMS) on the structure of Fe-Cu alloy layers

    NASA Astrophysics Data System (ADS)

    Nowakowska-Langier, Katarzyna; Chodun, Rafal; Nietubyc, Robert; Minikayev, Roman; Zdunek, Krzysztof

    2013-06-01

    This paper describes the study of the structural properties of the alloy layers prepared by two different, impulsively working PAPVD methods: the Pulsed Magnetron Sputtering (PMS) and the Impulse Plasma Deposition (IPD). The Fe-Cu alloy layers were synthesized. The results of our investigation revealed a nanocrystalline structure of the layers. The differences in the phase composition of the Fe-Cu alloy layers produced by these two methods were observed. The synthesis of the Fe-Cu layers by using the Pulsed Magnetron Sputtering method resulted in obtaining the two-phase, polycrystalline structures (fcc-Cu and bcc-Fe). In this case the clear evidence of mixing between the iron and copper atoms was not observed. The Fe-Cu layers deposited by the Impulse Plasma Deposition method were characterized by the non-equilibrium phase composition - the presence of one-phase supersaturated solid solution (fcc-Cu(Fe) or bcc-Fe(Cu)) was formed in immiscible systems. These results suggest a short-distance diffusion between the neighboring nanoparticles of the two metals (Cu and Fe) occurring during the IPD layers growth.

  3. Impulsive phase transport

    NASA Technical Reports Server (NTRS)

    Canfield, Richard C.; Bely-Dubau, Francoise; Brown, John C.; Dulk, George A.; Emslie, A. Gordon; Enome, Shinzo; Gabriel, Alan H.; Kundu, Mukul R.; Melrose, Donald; Neidig, Donald F.

    1986-01-01

    The transport of nonthermal electrons is explored. The thick-target electron beam model, in which electrons are presumed to be accelerated in the corona and typically thermalized primarily in the chromosphere and photosphere, is supported by observations throughout the electromagnetic spectrum. At the highest energies, the anisotropy of gamma-ray emission above 10 MeV clearly indicates that these photons are emitted by anisotropically-directed particles. The timing of this high-energy gamma-radiation with respect to lower-energy hard X-radiation implies that the energetic particles have short life-times. For collisional energy loss, this means that they are stopped in the chromosphere or below. Stereoscopic (two-spacecraft) observations at hard X-ray energies (up to 350 keV) imply that these lower-energy (but certainly nonthermal) electrons are also stopped deep in the chromosphere. Hard X-ray images show that, in spatially resolved flares whose radiation consists of impulsive bursts, the impulsive phase starts with X-radiation that comes mostly from the foot-points of coronal loops whose coronal component is outlined by microwaves.

  4. Development of a high specific 1.5 to 5 kW thermal arcjet

    NASA Technical Reports Server (NTRS)

    Riehle, M.; Glocker, B.; Auweter-Kurtz, M.; Kurtz, H.

    1993-01-01

    A research and development project on the experimental study of a 1.5-5 kW thermal arcjet thruster was started in 1992 at the IRS. Two radiation cooled thrusters were designed, constructed, and adapted to the test facilities, one at each end of the intended power range. These thrusters are currently subjected to an intensive test program with main emphasis on the exploration of thruster performance and thruster behavior at high specific enthalpy and thus high specific impulse. Propelled by simulated hydrazine and ammonia, the thruster's electrode configuration such as constrictor diameter and cathode gap was varied in order to investigate their influence and to optimize these parameters. In addition, test runs with pure hydrogen were performed for both thrusters.

  5. Helicopter impulsive noise: Theoretical and experimental status

    NASA Technical Reports Server (NTRS)

    Schmitz, F. H.; Yu, Y. H.

    1983-01-01

    The theoretical and experimental status of helicopter impulsive noise is reviewed. The two major source mechanisms of helicopter impulsive noise are addressed: high-speed impulsive noise and blade-vortex interaction impulsive noise. A thorough physical explanation of both generating mechanism is presented together with model and full-scale measurements of the phenomena. Current theoretical prediction methods are compared with experimental findings of isolated rotor tests. The noise generating mechanism of high speed impulsive noise are fairly well understood - theory and experiment compare nicely over Mach number ranges typical of today's helicopters. For the case of blade-vortex interaction noise, understanding of noise generating mechanisms and theoretical comparison with experiment are less satisfactory. Several methods for improving theory-experiment are suggested.

  6. Guidance and navigation requirements for unmanned flyby and swingby missions to the outer planets. Volume 2: impulsive high thrust missions, phase A

    NASA Technical Reports Server (NTRS)

    1969-01-01

    The impulsive, high thrust missions portion of a study on guidance and navigation requirements for unmanned flyby and swingby missions to the outer planet is presented. The proper balance between groundbased navigational capability, using the deep space network (DSN) alone, and an onboard navigational capability with and without supplemental use of DSN tracking, for unmanned missions to the outer planets of the solar system is defined. A general guidance and navigation requirements program is used to survey parametrically the characteristics associated with three types of navigation systems: (1) totally onboard, (2) totally Earth-based, and (3) a combination of these two.

  7. Angular dependence of plasma parameters and film properties during high power impulse magnetron sputtering for deposition of Ti and TiO2 layers

    NASA Astrophysics Data System (ADS)

    Hippler, R.; Hubicka, Z.; Cada, M.; Ksirova, P.; Wulff, H.; Helm, C. A.; Stranak, V.

    2017-05-01

    Angular distribution measurements have been carried out during High Power Impulse Magnetron Sputtering (HiPIMS) of a titanium target and deposition of titanium and titanium oxide films. The HiPIMS system was operated at a repetition frequency f = 100 Hz with a duty cycle of 1%. Langmuir probe diagnostics has been carried out at a distance of 7.5 cm from the target at four different angles with respect to the surface normal of the target. Film properties were investigated by means of SEM, XR, and GIXD, and a dependence of film thickness and crystalline structure on the deposition angle is observed.

  8. High repetition rate operation of a photoinitiated impulse-enhanced electrically excited CO2 laser discharge using a burst-mode technique

    NASA Astrophysics Data System (ADS)

    Nikumb, S. K.; Seguin, H. J. J.; Seguin, V. A.; Presakarchuk, D.

    1988-10-01

    The incorporation of a gating signal into the trigger circuit of a photoinitiated, impulse-enhanced, electrically excited (PIE) laser system has permitted high-power, pulsed operation of a normally cw CO2 discharge. The 40 liter gain medium has been run at repetition rates approaching 1 kHz utilizing this approach. Plasma uniformity and stability have been significantly enhanced, such that a factor of two increase in electrical power deposition into the excited volume has been achieved. Results suggest that pulsed performance considerably in excess of that achievable under cw operating conditions can be realized through the adoption of this simple modification to the PIE ionization process.

  9. Kinematics of the upper cervical spine during high velocity-low amplitude manipulation. Analysis of intra- and inter-operator reliability for pre-manipulation positioning and impulse displacements.

    PubMed

    Dugailly, Pierre-Michel; Beyer, Benoît; Sobczak, Stéphane; Salvia, Patrick; Rooze, Marcel; Feipel, Véronique

    2014-10-01

    To date, kinematics data analyzing continuous 3D motion of upper cervical spine (UCS) manipulation is lacking. This in vitro study aims at investigating inter- and intra-operator reliability of kinematics during high velocity low amplitude manipulation of the UCS. Three fresh specimens were used. Restricted dissection was realized to attach technical clusters to each bone (skull to C2). Motion data was obtained using an optoelectronic system during manipulation. Kinematics data were integrated into specific-subject 3D models to provide anatomical motion representation during thrust manipulation. The reliability of manipulation kinematics was assessed for three practitioners performing two sessions of three repetitions on two separate days. For pre-manipulation positioning, average UCS ROM (SD) were 10° (5°), 22° (5°) and 14° (4°) for lateral bending, axial rotation and flexion-extension, respectively. For the impulse phase, average axial rotation magnitude ranged from 7° to 12°. Reliability analysis showed average RMS up to 8° for pre-manipulation positioning and up to 5° for the impulse phase. As compared to physiological ROM, this study supports the limited angular displacement during manipulation for UCS motion components, especially for axial rotation. Kinematics reliability confirms intra- and inter-operator consistency although pre-manipulation positioning reliability is slightly lower between practitioners and sessions.

  10. Impulsivity moderates promotive environmental influences on adolescent delinquency: a comparison across family, school, and neighborhood contexts.

    PubMed

    Chen, Pan; Jacobson, Kristen C

    2013-10-01

    The present study examined moderating effects of impulsivity on the relationships between promotive factors from family (family warmth, parental knowledge), school (school connectedness), and neighborhood (neighborhood cohesion) contexts with delinquency using data collected from N = 2,978 sixth to eighth graders from 16 schools surrounding a major city in the Midwestern United States. More than half of the respondents were non-Caucasian (M age  = 12.48; 41.0 % male). Multilevel modeling analyses were conducted to take into account the clustering of the participants within schools. Impulsivity was positively associated with adolescent delinquency. Additionally, family warmth, parental knowledge, and school connectedness, but not neighborhood cohesion, were independently and inversely related to adolescent delinquency. Finally, impulsivity moderated relationships between family warmth and parental knowledge with delinquency but not relationships between school attachment and neighborhood cohesion with delinquency. Specifically, the negative relationship between family warmth and delinquency was significant for adolescents with high levels of, but not for those with below-average levels of, impulsivity. In addition, parental knowledge had a stronger association with decreased levels of delinquency for adolescents reporting higher levels of impulsivity. The moderating effects of impulsivity did not differ for males and females or for minority and non-minority participants. Findings indicate that impulsivity may have greater impact on adolescents' susceptibility to positive family influences than on their susceptibility to promotive factors from school or neighborhood contexts. Implications for future research and practice are discussed.

  11. High-intensity drying processes -- Impulse drying: Report 14 (progress report). Status of the pilot-scale research program

    SciTech Connect

    Orloff, D.I.

    1998-04-01

    As of April 1998, the project was behind on schedule. This was as a result of the need for additional process development work. Work has focused on evaluating nip decompression and post-nip depressurization techniques as used on the Beloit X2 pilot paper machine. The authors have also concentrated on implementing impulse drying technology on Beloit`s No. 4 and No. 2 pilot paper machines. Experiments on Beloit`s X4 pilot paper machine demonstrated that roll coating durability problems have been solved. They also showed that further development work on sheet picking, implementation of delamination suppression techniques and CD temperature control are necessary in order to ensure success on the X4 machine. Experiments on the Beloit`s X2 pilot paper machine were carried out to resolve issues identified on the X4 machine. Two methods of implementing press nip decompression were investigated. The results confirmed that the technology can be used to increase impulse drying operating temperatures. The work also led to the development of techniques to minimize picking.

  12. The Latent Structure of Impulsivity: Impulsive Choice, Impulsive Action, and Impulsive Personality Traits

    PubMed Central

    MacKillop, James; Weafer, Jessica; Gray, Joshua; Oshri, Assaf; Palmer, Abraham; de Wit, Harriet

    2016-01-01

    Rationale Impulsivity has been strongly linked to addictive behaviors, but can be operationalized in a number of ways that vary considerably in overlap, suggesting multidimensionality. Objective This study tested the hypothesis that the latent structure among multiple measures of impulsivity would reflect three broad categories: impulsive choice, reflecting discounting of delayed rewards; impulsive action, reflecting ability to inhibit a prepotent motor response; and impulsive personality traits, reflecting self-reported attributions of self-regulatory capacity. Methods The study used a cross-sectional confirmatory factor analysis of multiple impulsivity assessments. Participants were 1252 young adults (62% female) with low levels of addictive behavior who were assessed in individual laboratory rooms at the University of Chicago and the University of Georgia. The battery comprised a delay discounting task, Monetary Choice Questionnaire, Conners Continuous Performance Test, Go/NoGo Task, Stop Signal Task, Barratt Impulsivity Scale, and the UPPS-P Impulsive Behavior Scale. Results The hypothesized three-factor model provided the best fit to the data, although Sensation Seeking was excluded from the final model. The three latent factors were largely unrelated to each other and were variably associated with substance use. Conclusions These findings support the hypothesis that diverse measures of impulsivity can broadly be organized into three categories that are largely distinct from one another. These findings warrant investigation among individuals with clinical levels of addictive behavior and may be applied to understanding the underlying biological mechanisms of these categories. PMID:27449350

  13. Nerve Impulses in Plants

    ERIC Educational Resources Information Center

    Blatt, F. J.

    1974-01-01

    Summarizes research done on the resting and action potential of nerve impulses, electrical excitation of nerve cells, electrical properties of Nitella, and temperature effects on action potential. (GS)

  14. Nerve Impulses in Plants

    ERIC Educational Resources Information Center

    Blatt, F. J.

    1974-01-01

    Summarizes research done on the resting and action potential of nerve impulses, electrical excitation of nerve cells, electrical properties of Nitella, and temperature effects on action potential. (GS)

  15. Measuring Impulsivity in Adolescents with Serious Substance and Conduct Problems

    ERIC Educational Resources Information Center

    Thompson, Laetitia L.; Whitmore, Elizabeth A.; Raymond, Kristen M.; Crowley, Thomas J.

    2006-01-01

    Adolescents with substance use and conduct disorders have high rates of aggression and attention deficit hyperactivity disorder (ADHD), all of which have been characterized in part by impulsivity. Developing measures that capture impulsivity behaviorally and correlate with self-reported impulsivity has been difficult. One promising behavioral…

  16. Measuring Impulsivity in Adolescents with Serious Substance and Conduct Problems

    ERIC Educational Resources Information Center

    Thompson, Laetitia L.; Whitmore, Elizabeth A.; Raymond, Kristen M.; Crowley, Thomas J.

    2006-01-01

    Adolescents with substance use and conduct disorders have high rates of aggression and attention deficit hyperactivity disorder (ADHD), all of which have been characterized in part by impulsivity. Developing measures that capture impulsivity behaviorally and correlate with self-reported impulsivity has been difficult. One promising behavioral…

  17. Production of high specific activity silicon-32

    DOEpatents

    Phillips, Dennis R.; Brzezinski, Mark A.

    1994-01-01

    A process for preparation of silicon-32 is provide and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution to from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidization state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.

  18. Long-term, calorie-restricted intake of a high-fat diet in rats reduces impulse control and ventral striatal D2 receptor signalling - two markers of addiction vulnerability.

    PubMed

    Adams, Wendy K; Sussman, Jacob L; Kaur, Sukhbir; D'souza, Anna M; Kieffer, Timothy J; Winstanley, Catharine A

    2015-12-01

    High impulsivity, mediated through ventral striatal dopamine signalling, represents an established risk factor for substance abuse, and may likewise confer vulnerability to pathological overeating. Mechanistically, the assumption is that trait impulsivity facilitates the initiation of maladaptive eating styles or choices. However, whether consumption of appetitive macronutrients themselves causes deficits in impulse control and striatal signalling, thereby contributing to cognitive changes permissive of overeating behaviour, has yet to be considered. We examined the effects of chronic maintenance on restricted equicaloric, but high-fat or high-sugar, diets (48 kcal/day; 60 kcal% fat or sucrose) on rats' performance in the five-choice serial reaction time task, indexing impulsivity and attention. Markers of dopamine signalling in the dorsal and ventral striatum, and plasma insulin and leptin levels, were also assessed. Rats maintained on the high-fat diet (HFD) were more impulsive, whereas the high-sugar diet (HSD) did not alter task performance. Importantly, body weight and hormone levels were similar between groups when behavioural changes were observed. Maintenance on HFD, but not on HSD, reduced the levels of dopamine D2 receptor (D2 R), cAMP response element-binding protein (CREB) and phosphophorylated CREB (Ser133) proteins in the ventral, but not dorsal, striatum. D2 R expression in the ventral striatum also negatively correlated with impulsive responding, independently of diet. These data indicate that chronic exposure to even limited amounts of high-fat foods may weaken impulse control and alter neural signalling in a manner associated with vulnerability to addictions - findings that have serious implications for the propagation of uncontrolled eating behaviour in obesity and binge-eating disorder.

  19. Successful restrained eating and trait impulsiveness.

    PubMed

    van Koningsbruggen, Guido M; Stroebe, Wolfgang; Aarts, Henk

    2013-01-01

    Restrained eaters with high scores on the Perceived Self-Regulatory Success in Dieting Scale (PSRS) are more successful than low scorers in regulating their food intake. According to the theory of temptation-elicited goal activation (Fishbach, Friedman, & Kruglanski, 2003), they have become successful because, due to earlier repeated instances of successful self-control, they formed an associative link between temptations and thoughts of dieting. It is unclear, however, why they should have been more successful in earlier attempts at self-control than their unsuccessful counterparts. We examined whether trait impulsiveness plays a role by investigating the associations between dietary restraint, trait impulsiveness, and PSRS. Results showed that the interaction between dietary restraint and impulsiveness predicted dieting success: A lower level of impulsiveness was associated with greater dieting success among restrained eaters. These results suggest that restrained eaters who are less impulsive are more likely to become successful restrained eaters as identified with the PSRS.

  20. Dimensions of impulsive behavior in adolescents: laboratory behavioral assessments.

    PubMed

    Reynolds, Brady; Penfold, Robert B; Patak, Michele

    2008-04-01

    Impulsivity is a multifaceted construct that defines a range of maladaptive behavioral styles. The present research aimed to identify different dimensions of impulsive behavior in adolescents from a battery of laboratory behavioral assessments. In one analysis, correlations were examined between two self report and seven laboratory behavioral measures of impulsivity. The correlation between the two self report measures was high compared to correlations between the self report and laboratory behavioral measures. In a second analysis, a principal components analysis was performed with just the laboratory behavioral measures. Three behavioral dimensions were identified -- "impulsive decision-making", "impulsive inattention", and "impulsive disinhibition". These dimensions were further evaluated using the same sample with a confirmatory factor analysis, which did support the hypothesis that these are significant and independent dimensions of impulsivity. This research indicates there are at least three separate subtypes of impulsive behavior when using laboratory behavioral assessments with adolescent participants.

  1. [Differentiation of impulsive crimes from crimes of passion].

    PubMed

    Marneros, A

    2007-11-01

    In this article we try to differentiate between impulsive crimes and crimes of passion. The former are all impulsively executed and unplanned aggressive acts where we can find no specific preceding events which can be derived from a relevant relationship between offender and victim. Crimes of passion on the other hand are also impulsive and aggressive acts executed in a highly stressful affective state, but they are directed towards another relevant person and characterized by specific preceding events derived from the relationship between offender and victim. Thus they result from a perceived threat to the offender's self-image. We outline features for assessing crimes of passion as well as some indications which could facilitate them. The above mentioned differentiation between impulsive crimes and crimes of passion is relevant in forensic practice. Assessment of the psychological and psychopathological processes and states described in this article allows forensic psychiatric experts to give more reliable and more distinct recommendations to a court regarding the offender's criminal responsibility.

  2. Impulsive social influence increases impulsive choices on a temporal discounting task in young adults.

    PubMed

    Gilman, Jodi M; Curran, Max T; Calderon, Vanessa; Stoeckel, Luke E; Evins, A Eden

    2014-01-01

    Adolescents and young adults who affiliate with friends who engage in impulsive behavior are more likely to engage in impulsive behaviors themselves, and those who associate with prosocial (i.e. more prudent, future oriented) peers are more likely to engage in prosocial behavior. However, it is difficult to disentangle the contribution of peer influence vs. peer selection (i.e., whether individuals choose friends with similar traits) when interpreting social behaviors. In this study, we combined a novel social manipulation with a well-validated delay discounting task assessing impulsive behavior to create a social influence delay discounting task, in which participants were exposed to both impulsive (smaller, sooner or SS payment) and non-impulsive (larger, later or LL payment) choices from their peers. Young adults in this sample, n = 51, aged 18-25 had a higher rate of SS choices after exposure to impulsive peer influence than after exposure to non-impulsive peer influence. Interestingly, in highly susceptible individuals, the rate of non-impulsive choices did not increase after exposure to non-impulsive influence. There was a positive correlation between self-reported suggestibility and degree of peer influence on SS choices. These results suggest that, in young adults, SS choices appear to be influenced by the choices of same-aged peers, especially for individuals who are highly susceptible to influence.

  3. Impulsive Social Influence Increases Impulsive Choices on a Temporal Discounting Task in Young Adults

    PubMed Central

    Gilman, Jodi M.; Curran, Max T.; Calderon, Vanessa; Stoeckel, Luke E.; Evins, A. Eden

    2014-01-01

    Adolescents and young adults who affiliate with friends who engage in impulsive behavior are more likely to engage in impulsive behaviors themselves, and those who associate with prosocial (i.e. more prudent, future oriented) peers are more likely to engage in prosocial behavior. However, it is difficult to disentangle the contribution of peer influence vs. peer selection (i.e., whether individuals choose friends with similar traits) when interpreting social behaviors. In this study, we combined a novel social manipulation with a well-validated delay discounting task assessing impulsive behavior to create a social influence delay discounting task, in which participants were exposed to both impulsive (smaller, sooner or SS payment) and non-impulsive (larger, later or LL payment) choices from their peers. Young adults in this sample, n = 51, aged 18–25 had a higher rate of SS choices after exposure to impulsive peer influence than after exposure to non-impulsive peer influence. Interestingly, in highly susceptible individuals, the rate of non-impulsive choices did not increase after exposure to non-impulsive influence. There was a positive correlation between self-reported suggestibility and degree of peer influence on SS choices. These results suggest that, in young adults, SS choices appear to be influenced by the choices of same-aged peers, especially for individuals who are highly susceptible to influence. PMID:24988440

  4. A Neurogenetic Approach to Impulsivity

    PubMed Central

    Congdon, Eliza; Canli, Turhan

    2008-01-01

    Impulsivity is a complex and multidimensional trait that is of interest to both personality psychologists and to clinicians. For investigators seeking the biological basis of personality traits, the use of neuroimaging techniques such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) revolutionized personality psychology in less than a decade. Now, another revolution is under way, and it originates from molecular biology. Specifically, new findings in molecular genetics, the detailed mapping and the study of the function of genes, have shown that individual differences in personality traits can be related to individual differences within specific genes. In this article, we will review the current state of the field with respect to the neural and genetic basis of trait impulsivity. PMID:19012655

  5. Rethinking Impulsivity in Suicide

    ERIC Educational Resources Information Center

    Klonsky, E. David; May, Alexis

    2010-01-01

    Elevated impulsivity is thought to facilitate the transition from suicidal thoughts to suicidal behavior. Therefore, impulsivity should distinguish those who have attempted suicide (attempters) from those who have only considered suicide (ideators-only). This hypothesis was examined in three large nonclinical samples: (1) 2,011 military recruits,…

  6. Rethinking Impulsivity in Suicide

    ERIC Educational Resources Information Center

    Klonsky, E. David; May, Alexis

    2010-01-01

    Elevated impulsivity is thought to facilitate the transition from suicidal thoughts to suicidal behavior. Therefore, impulsivity should distinguish those who have attempted suicide (attempters) from those who have only considered suicide (ideators-only). This hypothesis was examined in three large nonclinical samples: (1) 2,011 military recruits,…

  7. Dealing with Impulsivity.

    ERIC Educational Resources Information Center

    Neidhardt, Janet

    1987-01-01

    A mother recounts her neurologically impaired son's struggles and progress in combating impulsivity in his work and social habits. Now 23 years old, employed full-time, and off medication, the son is still impulsive, has problems with social skills, but has improved his self-image through a photography hobby. (CB)

  8. High flux isotope reactor technical specifications

    SciTech Connect

    Not Available

    1982-04-01

    Technical specifications are presented concerning safety limits and limiting safety system settings; limiting conditions for operation; surveillance requirements; design features; administrative controls; and accidents and anticipated transients.

  9. High-sucrose diets in male rats disrupt aspects of decision making tasks, motivation and spatial memory, but not impulsivity measured by operant delay-discounting.

    PubMed

    Wong, Alanna; Dogra, Vimi R; Reichelt, Amy C

    2017-03-30

    Excessive consumption of sugar sweetened drinks is proposed to produce functional changes in the hippocampus and prefrontal cortex, leading to perturbations in behavioural control. Impairments in behavioural control have been observed in obese people on tasks that involve making choices, including delay-discounting, indicative of increased impulsivity. In this study we examined the impact of 2h daily access to 10% sucrose (or no sucrose in controls) in young male rats on behavioural tasks reliant on hippocampal function including delay-discounting, T-maze forced choice alternation and place recognition memory, as well as progressive ratio to measure motivation. We observed deficits in place recognition memory and T-maze forced choice alternation, indicative of hippocampal deficits in rats with a history of sucrose consumption. Moreover, rats with a history of sucrose consumption were less motivated to lever press for rewards on a progressive ratio schedule. However, rats with a history of sucrose consumption performed equally to control animals during the delay-discounting task, suggesting that they discounted for reward size over a delay in a manner comparable to control animals. These findings indicate that high-sucrose diets impact on spatial and working memory processes, but do not induce impulsive-like choice behaviours in rats, suggesting that unhealthy diet choices may not influence this aspect of decision-making behaviour.

  10. Delay Discounting, Locus of Control, and Cognitive Impulsiveness Independently Predict Tobacco Dependence Treatment Outcomes in a Highly Dependent, Lower Socioeconomic Group of Smokers

    PubMed Central

    Sheffer, Christine; MacKillop, James; McGeary, John; Landes, Reid; Carter, Lawrence; Yi, Richard; Jones, Bryan; Christensen, Darren; Stitzer, Maxine; Jackson, Lisa; Bickel, Warren

    2013-01-01

    Tobacco use disproportionately affects lower socioeconomic status (SES) groups. Current explanations as to why lower SES groups respond less robustly to tobacco control efforts and tobacco dependence treatment do not fully account for this disparity. The identification of factors that predict relapse in this population might help to clarify these differences. Good candidates for novel prognostic factors include the constellation of behaviors associated with executive function including self-control/impulsiveness, the propensity to delay reward, and consideration and planning of future events. This study examined the ability of several measures of executive function and other key clinical, psychological, and cognitive factors to predict abstinence for highly dependent lower SES participants enrolled in intensive cognitive-behavioral treatment for tobacco dependence. Consistent with predictions, increased discounting and impulsiveness, an external locus of control as well as greater levels of nicotine dependence, stress, and smoking for negative affect reduction predicted relapse. These findings suggest that these novel factors are clinically relevant in predicting treatment outcomes and suggest new targets for therapeutic assessment and treatment approaches. PMID:22494224

  11. The relationship between impulsivity and impulse control disorders in Parkinson's disease.

    PubMed

    Isaias, Ioannis U; Siri, Chiara; Cilia, Roberto; De Gaspari, Danilo; Pezzoli, Gianni; Antonini, Angelo

    2008-02-15

    A range of behaviors presumed to be related to dopaminergic medications have been recently recognized in Parkinson's disease (PD). We evaluated 50 consecutive cognitively intact PD patients on stable dopamine agonist and levodopa therapy and 100 healthy controls for compulsive sexual behavior, compulsive buying, or intermittent explosive disorders assessed by the Minnesota Impulsive Disorders Interview (MIDI), pathological gambling (South Oaks Gambling Screen, SOGS), impulsivity (Barratt Impulsiveness Scale), compulsivity (Maudsley obsessional-compulsive inventory), and depression scores (Geriatric Depression Scale). Overall 28% PD (14/50) and 20% healthy controls (20/100) reported at least one abnormal behavior at MIDI or pathological SOGS score. PD patients had higher scores than controls for impulsivity (P = 0.006), compulsivity (P < 0.001), and depression (P < 0.001). There was no correlation between impulsivity, compulsivity, and depression scores in PD. Male gender and higher impulsivity score, but not dose and kind of dopaminergic medications, were associated in PD with increased probability of impulsive disorders at MIDI. Impulse control disorders are also common in the control population. Individual susceptibility factors, such as high impulsivity and depression, underline abnormal behaviors in PD patients treated with stable dopaminergic therapy.

  12. High specific energy, high capacity nickel-hydrogen cell design

    NASA Technical Reports Server (NTRS)

    Wheeler, James R.

    1993-01-01

    A 3.5 inch rabbit-ear-terminal nickel-hydrogen cell was designed and tested to deliver high capacity at steady discharge rates up to and including a C rate. Its specific energy yield of 60.6 wh/kg is believed to be the highest yet achieved in a slurry-process nickel-hydrogen cell, and its 10 C capacity of 113.9 AH the highest capacity yet of any type in a 3.5 inch diameter size. The cell also demonstrated a pulse capability of 180 amps for 20 seconds. Specific cell parameters and performance are described. Also covered is an episode of capacity fading due to electrode swelling and its successful recovery by means of additional activation procedures.

  13. Premotor functional connectivity predicts impulsivity in juvenile offenders.

    PubMed

    Shannon, Benjamin J; Raichle, Marcus E; Snyder, Abraham Z; Fair, Damien A; Mills, Kathryn L; Zhang, Dongyang; Bache, Kevin; Calhoun, Vince D; Nigg, Joel T; Nagel, Bonnie J; Stevens, Alexander A; Kiehl, Kent A

    2011-07-05

    Teenagers are often impulsive. In some cases this is a phase of normal development; in other cases impulsivity contributes to criminal behavior. Using functional magnetic resonance imaging, we examined resting-state functional connectivity among brain systems and behavioral measures of impulsivity in 107 juveniles incarcerated in a high-security facility. In less-impulsive juveniles and normal controls, motor planning regions were correlated with brain networks associated with spatial attention and executive control. In more-impulsive juveniles, these same regions correlated with the default-mode network, a constellation of brain areas associated with spontaneous, unconstrained, self-referential cognition. The strength of these brain-behavior relationships was sufficient to predict impulsivity scores at the individual level. Our data suggest that increased functional connectivity of motor-planning regions with networks subserving unconstrained, self-referential cognition, rather than those subserving executive control, heightens the predisposition to impulsive behavior in juvenile offenders. To further explore the relationship between impulsivity and neural development, we studied functional connectivity in the same motor-planning regions in 95 typically developing individuals across a wide age span. The change in functional connectivity with age mirrored that of impulsivity: younger subjects tended to exhibit functional connectivity similar to the more-impulsive incarcerated juveniles, whereas older subjects exhibited a less-impulsive pattern. This observation suggests that impulsivity in the offender population is a consequence of a delay in typical development, rather than a distinct abnormality.

  14. Premotor functional connectivity predicts impulsivity in juvenile offenders

    PubMed Central

    Shannon, Benjamin J.; Raichle, Marcus E.; Snyder, Abraham Z.; Fair, Damien A.; Mills, Kathryn L.; Zhang, Dongyang; Bache, Kevin; Calhoun, Vince D.; Nigg, Joel T.; Nagel, Bonnie J.; Stevens, Alexander A.; Kiehl, Kent A.

    2011-01-01

    Teenagers are often impulsive. In some cases this is a phase of normal development; in other cases impulsivity contributes to criminal behavior. Using functional magnetic resonance imaging, we examined resting-state functional connectivity among brain systems and behavioral measures of impulsivity in 107 juveniles incarcerated in a high-security facility. In less-impulsive juveniles and normal controls, motor planning regions were correlated with brain networks associated with spatial attention and executive control. In more-impulsive juveniles, these same regions correlated with the default-mode network, a constellation of brain areas associated with spontaneous, unconstrained, self-referential cognition. The strength of these brain–behavior relationships was sufficient to predict impulsivity scores at the individual level. Our data suggest that increased functional connectivity of motor-planning regions with networks subserving unconstrained, self-referential cognition, rather than those subserving executive control, heightens the predisposition to impulsive behavior in juvenile offenders. To further explore the relationship between impulsivity and neural development, we studied functional connectivity in the same motor-planning regions in 95 typically developing individuals across a wide age span. The change in functional connectivity with age mirrored that of impulsivity: younger subjects tended to exhibit functional connectivity similar to the more-impulsive incarcerated juveniles, whereas older subjects exhibited a less-impulsive pattern. This observation suggests that impulsivity in the offender population is a consequence of a delay in typical development, rather than a distinct abnormality. PMID:21709236

  15. Final report of LDRD project: Electromagnetic impulse radar for detection of underground structures

    SciTech Connect

    Loubriel, G.; Aurand, J.; Buttram, M.; Zutavern, F.; Brown, D.; Helgeson, W.

    1998-03-01

    This report provides a summary of the LDRD project titled: Electromagnetic impulse radar for the detection of underground structures. The project met all its milestones even with a tight two year schedule and total funding of $400 k. The goal of the LDRD was to develop and demonstrate a ground penetrating radar (GPR) that is based on high peak power, high repetition rate, and low center frequency impulses. The idea of this LDRD is that a high peak power, high average power radar based on the transmission of short impulses can be utilized effect can be utilized for ground penetrating radar. This direct time-domain system the authors are building seeks to increase penetration depth over conventional systems by using: (1) high peak power, high repetition rate operation that gives high average power, (2) low center frequencies that better penetrate the ground, and (3) short duration impulses that allow for the use of downward looking, low flying platforms that increase the power on target relative to a high flying platform. Specifically, chirped pulses that are a microsecond in duration require (because it is difficult to receive during transmit) platforms above 150 m (and typically 1 km) while this system, theoretically could be at 10 m above the ground. The power on target decays with distance squared so the ability to use low flying platforms is crucial to high penetration. Clutter is minimized by time gating the surface clutter return. Short impulses also allow gating (out) the coupling of the transmit and receive antennas.

  16. Multidimensional Examination of Impulsivity in Relation to Disordered Gambling

    PubMed Central

    MacKillop, James; Miller, Joshua D.; Fortune, Erica; Maples, Jessica; Lance, Charles E.; Campbell, W. Keith; Goodie, Adam S.

    2014-01-01

    Impulsivity has been consistently associated with pathological gambling (PG), but the diversity of definitions and measures of impulsivity has led to ambiguity with regard to which indices are independently relevant. Toward clarifying this relationship, the current study examined indices from an array of commonly-used impulsivity measures in relation to PG severity in an adult community sample of frequent gamblers (N = 353). These included both survey assessments and behavioral tasks. Using a factor analytic approach, four latent factors were identified among 19 indices and were designated reward sensitivity, punishment sensitivity, delay discounting, and cognitive impulsivity. All four latent variables were positively and independently related to PG severity, albeit at a trend level for cognitive impulsivity in a combined model. These findings reveal four generally independent domains of impulsivity that are related to PG severity, clarify which assessment measures aggregate in each domain, and illustrate the importance of measurement specificity in studying impulsivity in relation to PG and other psychiatric disorders. PMID:24708148

  17. Gamma Aminobutyric Acidergic and Neuronal Structural Markers in the Nucleus Accumbens Core Underlie Trait-like Impulsive Behavior

    PubMed Central

    Caprioli, Daniele; Sawiak, Stephen J.; Merlo, Emiliano; Theobald, David E.H.; Spoelder, Marcia; Jupp, Bianca; Voon, Valerie; Carpenter, T. Adrian; Everitt, Barry J.; Robbins, Trevor W.; Dalley, Jeffrey W.

    2014-01-01

    Background Pathological forms of impulsivity are manifest in a number of psychiatric disorders listed in DSM-5, including attention-deficit/hyperactivity disorder and substance use disorder. However, the molecular and cellular substrates of impulsivity are poorly understood. Here, we investigated a specific form of motor impulsivity in rats, namely premature responding, on a five-choice serial reaction time task. Methods We used in vivo voxel-based magnetic resonance imaging and ex vivo Western blot analyses to investigate putative structural, neuronal, and glial protein markers in low-impulsive (LI) and high-impulsive rats. We also investigated whether messenger RNA interference targeting glutamate decarboxylase 65/67 (GAD65/67) gene expression in the nucleus accumbens core (NAcbC) is sufficient to increase impulsivity in LI rats. Results We identified structural and molecular abnormalities in the NAcbC associated with motor impulsivity in rats. We report a reduction in gray matter density in the left NAcbC of high-impulsive rats, with corresponding reductions in this region of glutamate decarboxylase (GAD65/67) and markers of dendritic spines and microtubules. We further demonstrate that the experimental reduction of de novo of GAD65/67 expression bilaterally in the NAcbC is sufficient to increase impulsivity in LI rats. Conclusions These results reveal a novel mechanism of impulsivity in rats involving gamma aminobutyric acidergic and structural abnormalities in the NAcbC with potential relevance to the etiology and treatment of attention-deficit/hyperactivity disorder and related disorders. PMID:23973096

  18. Measuring Specific Heats at High Temperatures

    NASA Technical Reports Server (NTRS)

    Vandersande, Jan W.; Zoltan, Andrew; Wood, Charles

    1987-01-01

    Flash apparatus for measuring thermal diffusivities at temperatures from 300 to 1,000 degrees C modified; measures specific heats of samples to accuracy of 4 to 5 percent. Specific heat and thermal diffusivity of sample measured. Xenon flash emits pulse of radiation, absorbed by sputtered graphite coating on sample. Sample temperature measured with thermocouple, and temperature rise due to pulse measured by InSb detector.

  19. Cross-correlation between vagal afferent impulses from pulmonary mechanoreceptors and high-frequency inflation (HFI) and deflation (HFD) in rabbits.

    PubMed

    Homma, I; Isobe, A; Iwase, M; Onimaru, H; Sibuya, M

    1987-04-10

    The effects of high-frequency airway inflation (HFI) and high-frequency airway deflation (HFD) generated by a triangular pressure pulse generator on pulmonary mechanoreceptors were examined. The cross-correlograms between vagal afferent impulses from the slowly adapting (SAR) and the rapidly adapting receptors (RAR) and the HFI or the HFD pulses were analysed. HFI stimulated SAR and RAR and HFD stimulated RAR, but inhibited SAR. The time lag of the mode in the correlogram between SAR and HFI was shorter than that of the mode in the correlogram between RAR and HFI. The span of the mode and the trough of SAR was shorter than the span of the mode of RAR. This may indicate that the time to peak of the generator potential of RAR is longer than that of SAR.

  20. Unilateral vestibular deafferentation (UVD) causes permanent asymmetry in the gain of the yaw VOR to high acceleration head impulses in guinea pigs.

    PubMed

    Curthoys, I S; Topple, A N; Halmagyi, G M

    1995-01-01

    Using an acute scleral search coil technique for measuring eye position in alert animals we have shown that after UVD the yaw VOR in the guinea pig shows a permanent gain asymmetry. There is a reduced gain during the first 100 ms of brief, high acceleration horizontal head rotations ("yaw head impulses") towards the operated side, but only a small loss in gain for similar rotations towards the intact side. This result confirms that the horizontal E response during the first 100 ms of an abrupt high acceleration head rotation is a clear indicator of the function of the horizontal canal. These results are similar to those in human patients after unilateral acoustic neuroma operations. The asymmetry in response is large shortly after UVD and decreases over time but is permanent.

  1. Experimental confirmation and physical understanding of ultra-high bit rate impulse radio in the THz digital communication channels of the atmosphere

    NASA Astrophysics Data System (ADS)

    Mandehgar, Mahboubeh; Yang, Yihong; Grischkowsky, D.

    2014-09-01

    We have performed highly accurate numerical calculations of high bit rate impulse propagation through the seven digital communication channels of the atmosphere at RH 58% (10 g m-3). These calculations maximized bit rates for pathlengths equal to or longer than 100 m. We have experimentally verified our calculations for three channels with a propagation pathlength of 137 m and RH 65% (11.2 g m-3). Excellent agreement between measurement and theory was obtained for Channel 3 at 252 GHz, bit rate 84 Gb s-1, FWHM bandwidth (BW) 180 GHz; Channel 6 at 672 GHz, 45 Gb s-1, BW 84 GHz; and Channel 7 at 852 GHz, 56.8 Gb s-1, BW 108 GHz.

  2. [Impulsiveness Among Short-Term Prisoners with Antisocial Personality Disorder].

    PubMed

    Lang, Fabian U; Otte, Stefanie; Vasic, Nenad; Jäger, Markus; Dudeck, Manuela

    2015-07-01

    The study aimed to investigate the correlation between impulsiveness and the antisocial personality disorder among short-term prisoners. The impulsiveness was diagnosed by the Barratt Impulsiveness Scale (BIS). Short-term prisoners with antisocial personality disorder scored significant higher marks on the BIS total scale than those without any personality disorder. In detail, they scored higher marks on each subscale regarding attentional, motor and nonplanning impulsiveness. Moderate and high effects were calculated. It is to be considered to regard impulsivity as a conceptual component of antisociality. © Georg Thieme Verlag KG Stuttgart · New York.

  3. Spin Stabilized Impulsively Controlled Missile (SSICM)

    NASA Astrophysics Data System (ADS)

    Crawford, J. I.; Howell, W. M.

    1985-12-01

    This patent is for the Spin Stabilized Impulsively Controlled Missile (SSICM). SSICM is a missile configuration which employs spin stabilization, nutational motion, and impulsive thrusting, and a body mounted passive or semiactive sensor to achieve very small miss distances against a high speed moving target. SSICM does not contain an autopilot, control surfaces, a control actuation system, nor sensor stabilization gimbals. SSICM spins at a rate sufficient to provide frequency separation between body motions and inertial target motion. Its impulsive thrusters provide near instantaneous changes in lateral velocity, whereas conventional missiles require a significant time delay to achieve lateral acceleration.

  4. Fractionating impulsivity: neuropsychiatric implications.

    PubMed

    Dalley, Jeffrey W; Robbins, Trevor W

    2017-02-17

    The ability to make decisions and act quickly without hesitation can be advantageous in many settings. However, when persistently expressed, impulsive decisions and actions are considered risky, maladaptive and symptomatic of such diverse brain disorders as attention-deficit hyperactivity disorder, drug addiction and affective disorders. Over the past decade, rapid progress has been made in the identification of discrete neural networks that underlie different forms of impulsivity - from impaired response inhibition and risky decision making to a profound intolerance of delayed rewards. Herein, we review what is currently known about the neural and psychological mechanisms of impulsivity, and discuss the relevance and application of these new insights to various neuropsychiatric disorders.

  5. Impulsivity and emotion dysregulation as predictors of food addiction.

    PubMed

    Pivarunas, Bernadette; Conner, Bradley T

    2015-12-01

    Food addiction is the clinical occurrence in which individuals develop physical and psychological dependencies on high fat, high sugar, and highly palatable foods. Past research has demonstrated a number of similarities between food addiction and drug use disorders including the activation of specific brain regions and neurotransmitters, disrupted neuronal circuitry, and behavioral indicators of addiction such as continued use despite negative consequences. The present study examined the role of impulsivity and emotion dysregulation in food addiction as both play salient roles in drug use disorders. Poisson regression analyses using data from 878 undergraduate students revealed negative urgency, the tendency to act impulsively when under distress, and emotion dysregulation positively predicted symptom count on the Yale Food Addiction Scale (Gearhardt, Corbin, & Brownell, 2009) whereas a lack of premeditation negatively predicted symptom count (all ps<0.05). Future research is needed to confirm precursors to eating episodes in food addiction, elucidate causal mechanisms, and support an explanatory model of food addiction.

  6. Icing tunnel tests of Electro-Impulse De-Icing of an engine inlet and high-speed wings

    NASA Technical Reports Server (NTRS)

    Zumwalt, G. W.

    1985-01-01

    A brief review is given of four earlier tests in the NASA Lewis Icing Research Tunnel and of flight tests in NASA's Icing Research Aircraft and in a Cessna 206 airplane. Details are given of recent icing tunnel tests of thicker-skinned wings, a Gates Learjet, a composite leading edge, and a Boeing 767, and of a Falcon Fanjet engine inlet. These were tested at speeds from 87 to 220 knots, air temperatures from -2 to -15 C, LWC values of 0.6 to 2.4 grams/cu meter, and median droplet diameters from 12 to 20 microns. Energy requirements are reported, as well as conclusions from comparisons of several Electro-Impulse De-Icing coil system designs. Fundamental studies of the structural dynamics and ice shedding of a 12.7 cm (5 inch) diameter semicylinder are described. Some potential problem areas are discussed: fatigue of skin and coil mountings, system weight and cost, electro-magnetic interference and noise.

  7. Lower Monoamine Oxidase-A Total Distribution Volume in Impulsive and Violent Male Offenders with Antisocial Personality Disorder and High Psychopathic Traits: An [11C] Harmine Positron Emission Tomography Study

    PubMed Central

    Kolla, Nathan J; Matthews, Brittany; Wilson, Alan A; Houle, Sylvain; Michael Bagby, R; Links, Paul; Simpson, Alexander I; Hussain, Amina; Meyer, Jeffrey H

    2015-01-01

    Antisocial personality disorder (ASPD) often presents with highly impulsive, violent behavior, and pathological changes in the orbitofrontal cortex (OFC) and ventral striatum (VS) are implicated. Several compelling reasons support a relationship between low monoamine oxidase-A (MAO-A), an enzyme that regulates neurotransmitters, and ASPD. These include MAO-A knockout models in rodents evidencing impulsive aggression and positron emission tomography (PET) studies of healthy subjects reporting associations between low brain MAO-A levels and greater impulsivity or aggression. However, a fundamental gap in the literature is that it is unknown whether brain MAO-A levels are low in more severe, clinical disorders of impulsivity, such as ASPD. To address this issue, we applied [11C] harmine PET to measure MAO-A total distribution volume (MAO-A VT), an index of MAO-A density, in 18 male ASPD participants and 18 age- and sex-matched controls. OFC and VS MAO-A VT were lower in ASPD compared with controls (multivariate analysis of variance (MANOVA): F2,33=6.8, P=0.003; OFC and VS MAO-A VT each lower by 19%). Similar effects were observed in other brain regions: prefrontal cortex, anterior cingulate cortex, dorsal putamen, thalamus, hippocampus, and midbrain (MANOVA: F7,28=2.7, P=0.029). In ASPD, VS MAO-A VT was consistently negatively correlated with self-report and behavioral measures of impulsivity (r=−0.50 to −0.52, all P-values<0.05). This study is the first to demonstrate lower brain MAO-A levels in ASPD. Our results support an important extension of preclinical models of impulsive aggression into a human disorder marked by pathological aggression and impulsivity. PMID:26081301

  8. Lower Monoamine Oxidase-A Total Distribution Volume in Impulsive and Violent Male Offenders with Antisocial Personality Disorder and High Psychopathic Traits: An [(11)C] Harmine Positron Emission Tomography Study.

    PubMed

    Kolla, Nathan J; Matthews, Brittany; Wilson, Alan A; Houle, Sylvain; Bagby, R Michael; Links, Paul; Simpson, Alexander I; Hussain, Amina; Meyer, Jeffrey H

    2015-10-01

    Antisocial personality disorder (ASPD) often presents with highly impulsive, violent behavior, and pathological changes in the orbitofrontal cortex (OFC) and ventral striatum (VS) are implicated. Several compelling reasons support a relationship between low monoamine oxidase-A (MAO-A), an enzyme that regulates neurotransmitters, and ASPD. These include MAO-A knockout models in rodents evidencing impulsive aggression and positron emission tomography (PET) studies of healthy subjects reporting associations between low brain MAO-A levels and greater impulsivity or aggression. However, a fundamental gap in the literature is that it is unknown whether brain MAO-A levels are low in more severe, clinical disorders of impulsivity, such as ASPD. To address this issue, we applied [(11)C] harmine PET to measure MAO-A total distribution volume (MAO-A VT), an index of MAO-A density, in 18 male ASPD participants and 18 age- and sex-matched controls. OFC and VS MAO-A VT were lower in ASPD compared with controls (multivariate analysis of variance (MANOVA): F2,33=6.8, P=0.003; OFC and VS MAO-A VT each lower by 19%). Similar effects were observed in other brain regions: prefrontal cortex, anterior cingulate cortex, dorsal putamen, thalamus, hippocampus, and midbrain (MANOVA: F7,28=2.7, P=0.029). In ASPD, VS MAO-A VT was consistently negatively correlated with self-report and behavioral measures of impulsivity (r=-0.50 to -0.52, all P-values<0.05). This study is the first to demonstrate lower brain MAO-A levels in ASPD. Our results support an important extension of preclinical models of impulsive aggression into a human disorder marked by pathological aggression and impulsivity.

  9. Scale model ultrawideband impulse radar

    NASA Astrophysics Data System (ADS)

    Morgan, Michael A.

    1993-05-01

    The Transient Electromagnetic Scattering Laboratory (TESL) is described which employs a unique dual-channel ultra-wideband impulsive illuminating source. This is a free-field facility where targets are suspended within an anechoic chamber. A highly coherent primal step pulse is amplified by two GaAs wideband power amplifiers having complementary passbands which feed individual wideband horn antennas. This yields an effective 1 - 12 GHz impulse bandwidth. A high speed digital processing oscilloscope samples the output of a single receiving horn. The TESL has facilitated research into radar target identification using complex natural resonances. Theory and operational characteristics of the facility are discussed and technical improvements are described which have yielded significant improvement in both the effective bandwidth and the signal-to-noise ratio of transient scattering measurements. Experimental validations are shown which illustrate the level of fidelity attainable and consideration is given to recent enhancements, including an increase of measurement bandwidth to 50 GHz.

  10. Impulsivity and psychopathy: associations between the barrett impulsivity scale and the psychopathy checklist revised.

    PubMed

    Snowden, Robert J; Gray, Nicola S

    2011-05-30

    Impulsivity is often cited as a core dysfunction in those who are high in psychopathic traits. However, both impulsivity and psychopathy are both multi-faceted constructs. We examined a 3-factor model of self-reported impulsivity (Barrett Impulsivity: BIS-11) against the 2-factor and 4-facet model of psychopathy as defined by the Psychopathy Checklist-Revised (PCL-R). Those high on 'secondary psychopathy' (Factor 2 and Facets 3 and 4 of the PCL-R) showed increased impulsivity as it related to acting with thinking (Motor Scale of BIS) and lack of future planning (Non-Planning scale of BIS), but not did not show any elevated features of poor concentration or distraction (Attention Scale of BIS). On the other hand, there was some evidence that 'primary psychopathy' (Factor 1 of PCL-R) was associated with reduced impulsivity as it relates to future planning (Non-Planning scale of BIS). Thus, our results show that only some psychopaths show increased impulsivity and that not all forms of impulsivity are raised.

  11. The Association Between Impulsivity and Alcohol/Drug Use Among Prison Inmates

    PubMed Central

    Bernstein, Michael H.; McSheffrey, Savannah N.; van den Berg, Jacob J.; Vela, Jamie E.; Stein, LAR; Roberts, Mary B.; Martin, Rosemarie A.; Clarke, Jennifer G.

    2015-01-01

    Background Few studies have examined the relation between impulsivity and drug involvement with prison inmates, in spite of their heavy drug use. Among this small body of work, most studies look at clinically relevant drug dependence, rather than drug use specifically. Method N=242 adult inmates (34.8% female, 52% White) with an average age of 35.58(SD=9.19) completed a modified version of the 15-item Barratt Impulsivity Scale (BIS) and measures assessing lifetime alcohol, opiates, benzodiazepines, cocaine, cannabis, hallucinogens, and polysubstance use. Lifetime users also reported the frequency of use for the 30 days prior to incarceration. Results Impulsivity was higher among lifetime users (versus never users) of all substances other than cannabis. Thirty day drug use frequency was only related to impulsivity for opiates and alcohol. Discussion This study extends prior work, by showing that a lifetime history of nonclinical substance use is positively associated with impulsivity among prison inmates. Implications for drug interventions are considered for this population, which is characterized by high rates of substance use and elevated impulsivity. PMID:25462662

  12. High specific activity platinum-195m

    SciTech Connect

    Mirzadeh, Saed; Du, Miting; Beets, Arnold L.; Knapp, Jr., Furn F.

    2004-10-12

    A new composition of matter includes .sup.195m Pt characterized by a specific activity of at least 30 mCi/mg Pt, generally made by method that includes the steps of: exposing .sup.193 Ir to a flux of neutrons sufficient to convert a portion of the .sup.193 Ir to .sup.195m Pt to form an irradiated material; dissolving the irradiated material to form an intermediate solution comprising Ir and Pt; and separating the Pt from the Ir by cation exchange chromatography to produce .sup.195m Pt.

  13. Different subtypes of impulsivity differentiate uncontrolled eating and dietary restraint.

    PubMed

    Leitch, Margaret A; Morgan, Michael J; Yeomans, Martin R

    2013-10-01

    The current study explored the relationship between three subtypes of impulsivity (Reflection Impulsivity, Impulsive Choice, and Impulsive Action) and measures of uncontrolled eating (TFEQ-D) and restraint (TFEQ-R). Eighty women classified as scoring higher or lower on TFEQ-D and TFEQ-R completed the Matching Familiar Figures Test (MFFT20), Delay Discounting Task (DDT), a Go No Go task, Balloon Analogue Risk Task (BART), and the Barrett Impulsivity Scale-11 (BIS-11). To test whether these relationships were affected by enforced controls overeating, half of the participants fasted the night before and ate breakfast in the laboratory before testing and half had no such control. Women scoring higher on the TFEQ-D were significantly more impulsive on the MFFT20 and BIS-11 overall but not on DDT, Go No Go or BART. Women scoring higher on TFEQ-R were significantly less impulsive on the Go No Go task but did not differ on other measures. The eating manipulation modulated responses on the BART and BIS-11 non-planning scale depending on TFEQ-D classification. These results confirm recent data that high scores on TFEQ-D are related to impulsivity, but imply this relates more to Reflection Impulsivity rather than Impulsive Choice or Action. In contrast restrained eating was associated with better inhibitory control. Taken together, these results suggest that subtypes of impulsivity further differentiate uncontrolled eating and restraint, and suggest that a poor ability to reflect on decisions may underlie some aspects of overeating.

  14. Near-Infrared Spectroscopy-Based Frontal Lobe Neurofeedback Integrated in Virtual Reality Modulates Brain and Behavior in Highly Impulsive Adults.

    PubMed

    Hudak, Justin; Blume, Friederike; Dresler, Thomas; Haeussinger, Florian B; Renner, Tobias J; Fallgatter, Andreas J; Gawrilow, Caterina; Ehlis, Ann-Christine

    2017-01-01

    Based on neurofeedback (NF) training as a neurocognitive treatment in attention-deficit/hyperactivity disorder (ADHD), we designed a randomized, controlled functional near-infrared spectroscopy (fNIRS) NF intervention embedded in an immersive virtual reality classroom in which participants learned to control overhead lighting with their dorsolateral prefrontal brain activation. We tested the efficacy of the intervention on healthy adults displaying high impulsivity as a sub-clinical population sharing common features with ADHD. Twenty participants, 10 in an experimental and 10 in a shoulder muscle-based electromyography control group, underwent eight training sessions across 2 weeks. Training was bookended by a pre- and post-test including go/no-go, n-back, and stop-signal tasks (SST). Results indicated a significant reduction in commission errors on the no-go task with a simultaneous increase in prefrontal oxygenated hemoglobin concentration for the experimental group, but not for the control group. Furthermore, the ability of the subjects to gain control over the feedback parameter correlated strongly with the reduction in commission errors for the experimental, but not for the control group, indicating the potential importance of learning feedback control in moderating behavioral outcomes. In addition, participants of the fNIRS group showed a reduction in reaction time variability on the SST. Results indicate a clear effect of our NF intervention in reducing impulsive behavior possibly via a strengthening of frontal lobe functioning. Virtual reality additions to conventional NF may be one way to improve the ecological validity and symptom-relevance of the training situation, hence positively affecting transfer of acquired skills to real life.

  15. Separation of formants from glottal impulses in high-resolution spectrograms using higher-order short-time Fourier transform (STFT) phase derivatives

    NASA Astrophysics Data System (ADS)

    Fulop, Sean A.

    2004-10-01

    The channelized instantaneous frequency of a signal x(T) is CIFx(ω,T)=(∂/∂T)arg(Fh(ω,T)), where Fh is the short-time Fourier transform of x(T) using window function h. The local group delay of a signal is LGDx(ω,T)=-(∂/∂ω)arg(Fh(ω,T)). For each point Fh(ω0,T0) in the STFT, the f-t coordinates [CIF(ω0,T0),t-LGD(ω0,T0)] pinpoint the local mean of the Rihacek distribution of complex signal energy, and this reassignment of the STFT magnitude yields a high-resolution spectrogram without blurriness [Auger and Flandrin, ``Improving the readability of time-frequency and time-scale representations by the reassignment method,'' IEEE Trans. Signal Process 43(5), 1068-1089 (1995)]. Nelson [``Instantaneous higher order phase derivatives,'' Digital Signal Process 12, 416-428 (2002)] demonstrated that the significant AM/FM components of a signal x(T) have (∂/∂ω)CIFx(ω,T)~=0. By plotting just those STFT points meeting this condition to within a threshold, a spectrogram showing only speech resonances can be drawn using short analysis frames. By moving to a long-frame analysis, the resonance tracker becomes an effective pitch and harmonic tracker. Nelson further demonstrated that the impulses in a signal x(T) have (∂/∂T)LGDx(ω,T)~=1. By plotting just those points meeting this condition to within a threshold, a spectrogram of speech impulses can alternatively be drawn.

  16. High Density Jet Fuel Supply and Specifications

    DTIC Science & Technology

    1986-01-01

    same shortcomings. Perhaps different LAK blends using heavy reformate or heavy cat cracker naphtha (both high in aromatics and isoparaffins) could... catalytic cracking (FCC) process. Subsequent investigations funded by the U. S. Air Force concentrated on producing a similar fuel from the...cut (19% overhead) and adding heavy naphtha (320-440F) from a nearby paraffinic crude (40"API Wyoming Sweet) an excellent JP-8X can be created. Table 5

  17. Temporal preparation, response inhibition and impulsivity.

    PubMed

    Correa, Angel; Triviño, Mónica; Pérez-Dueñas, Carolina; Acosta, Alberto; Lupiáñez, Juan

    2010-08-01

    Temporal preparation and impulsivity involve overlapping neural structures (prefrontal cortex) and cognitive functions (response inhibition and time perception), however, their interrelations had not been investigated. We studied such interrelations by comparing the performance of groups with low vs. high non-clinical trait impulsivity during a temporal preparation go no-go task. This task measured, in less than 10 min, how response inhibition was influenced both by temporal orienting of attention (guided by predictive temporal cues) and by sequential effects (produced by repetition/alternation of the duration of preparatory intervals in consecutive trials). The results showed that sequential effects produced dissociable patterns of temporal preparation as a function of impulsivity. Sequential effects facilitated both response speed (reaction times - RTs - to the go condition) and response inhibition (false alarms to the no-go condition) selectively in the low impulsivity group. In the high impulsivity group, in contrast, sequential effects only improved RTs but not response inhibition. We concluded that both excitatory and inhibitory processing may be enhanced concurrently by sequential effects, which enables the temporal preparation of fast and controlled responses. Impulsivity could hence be related to less efficient temporal preparation of that inhibitory processing. 2010 Elsevier Inc. All rights reserved.

  18. Dimensions of impulsive behavior in adolescent smokers and nonsmokers.

    PubMed

    Fields, Sherecce; Collins, Christine; Leraas, Kristen; Reynolds, Brady

    2009-10-01

    Robust associations have been identified between impulsive personality characteristics and cigarette smoking during adolescents, indicating that impulsive behavior may play an important role in the initiation of cigarette smoking. The present study extended this research by using laboratory behavioral assessments to explore relationships between three specific dimensions of impulsive behavior (impulsive decision-making, inattention, and disinhibition) and adolescent cigarette smoking. Participants were male and female adolescent smokers (n = 50) and nonsmokers (n = 50). Adolescent smokers were more impulsive on a measure of decision-making; however, there were significant smoking status by gender interaction effects for impulsive inattention and disinhibition. Male smokers were most impulsive on the measure of inattention, but male smokers were least impulsive on the measure of disinhibition. Correlations between biomarkers of smoking and impulsive inattention and disinhibition were found for females but not males. The current findings, coupled with previous findings (Reynolds et al., 2007), indicate there may be robust gender difference in associations between certain types of impulsive behavior and cigarette smoking during adolescence.

  19. Evaluating Eve: visceral states influence the evaluation of impulsive behavior.

    PubMed

    Nordgren, Loran F; van der Pligt, Joop; van Harreveld, Frenk

    2007-07-01

    Impulsive behavior is a common source of stigma. The authors argue that people often stigmatize impulsive behavior because they fail to appreciate the influence visceral impulses have on behavior. Because people tend to underestimate the motivational force of cravings for sex, drugs, food, and so forth, they are prone to stigmatize those who act on these impulses. In line with this reasoning, in 4 studies, the authors found that participants who were in a cold state (e.g., not hungry) made less favorable evaluations of a related impulsive behavior (impulsive eating) than did participants who were in a hot state (e.g., hungry). This empathy gap effect was tested with 3 different visceral states--fatigue, hunger, and sexual arousal--and was found both when participants evaluated others' impulsive behavior (Studies 1 & 2) and when participants evaluated their own impulsive behavior (Study 3). Study 3 also demonstrated that the empathy gap effect is due to different perceptions of the strength of the visceral state itself. Finally, Study 4 revealed that this effect is state specific: Hungry people, for example, evaluated only hunger-driven impulses, and not other forms of impulse, more favorably.

  20. Mixed-mode high-power impulse magnetron sputter deposition of tetrahedral amorphous carbon with pulse-length control of ionization

    SciTech Connect

    Tucker, M. D.; Marks, N. A.; Ganesan, R.; Bilek, M. M. M.; McKenzie, D. R.; McCulloch, D. G.; Partridge, J. G.; Stueber, M.; Ulrich, S.

    2016-04-21

    High-power impulse magnetron sputtering (HiPIMS) is used to deposit amorphous carbon thin films with sp{sup 3} fractions of 13% to 82%. Increasing the pulse length results in a transition from conventional HiPIMS deposition to a “mixed-mode” in which an arc triggers on the target surface, resulting in a large flux of carbon ions. The films are characterized using X-ray photoelectron spectroscopy, Raman spectroscopy, ellipsometry, nanoindentation, elastic recoil detection analysis, and measurements of stress and contact angle. All properties vary in a consistent manner, showing a high tetrahedral character only for long pulses, demonstrating that mixed-mode deposition is the source of the high carbon ion flux. Varying the substrate bias reveals an “energy window” effect, where the sp{sup 3} fraction of the films is greatest for a substrate bias around −100 V and decreases for higher or lower bias values. In the absence of bias, the films' properties show little dependence on the pulse length, showing that energetic ions are the origin of the highly tetrahedral character.

  1. Mixed-mode high-power impulse magnetron sputter deposition of tetrahedral amorphous carbon with pulse-length control of ionization

    NASA Astrophysics Data System (ADS)

    Tucker, M. D.; Ganesan, R.; McCulloch, D. G.; Partridge, J. G.; Stueber, M.; Ulrich, S.; Bilek, M. M. M.; McKenzie, D. R.; Marks, N. A.

    2016-04-01

    High-power impulse magnetron sputtering (HiPIMS) is used to deposit amorphous carbon thin films with sp3 fractions of 13% to 82%. Increasing the pulse length results in a transition from conventional HiPIMS deposition to a "mixed-mode" in which an arc triggers on the target surface, resulting in a large flux of carbon ions. The films are characterized using X-ray photoelectron spectroscopy, Raman spectroscopy, ellipsometry, nanoindentation, elastic recoil detection analysis, and measurements of stress and contact angle. All properties vary in a consistent manner, showing a high tetrahedral character only for long pulses, demonstrating that mixed-mode deposition is the source of the high carbon ion flux. Varying the substrate bias reveals an "energy window" effect, where the sp3 fraction of the films is greatest for a substrate bias around -100 V and decreases for higher or lower bias values. In the absence of bias, the films' properties show little dependence on the pulse length, showing that energetic ions are the origin of the highly tetrahedral character.

  2. Self-reported impulsivity, but not behavioral choice or response impulsivity, partially mediates the effect of stress on drinking behavior

    PubMed Central

    HAMILTON, KRISTEN R.; ANSELL, EMILY B.; REYNOLDS, BRADY; POTENZA, MARC N.; SINHA, RAJITA

    2013-01-01

    Stress and impulsivity contribute to alcohol use, and stress may also act via impulsivity to increase drinking behavior. Impulsivity represents a multi-faceted construct and self-report and behavioral assessments may effectively capture distinct clinically relevant factors. The present research investigated whether aspects of impulsivity mediate the effect of stress on alcohol use. A community-based sample of 192 men and women was assessed on measures of cumulative stress, alcohol use, self-reported impulsivity, and behavioral choice and response impulsivity. Data were analyzed using regression and bootstrapping techniques to estimate indirect effects of stress on drinking via impulsivity. Cumulative adversity exhibited both direct effects and indirect effects (via self-reported impulsivity) on drinking behavior. Additional models examining specific types of stress indicated direct and indirect effects of trauma and recent life events, and indirect effects of major life events and chronic stressors on drinking behavior. Overall, cumulative stress was associated with increased drinking behavior, and this effect was partially mediated by self-reported impulsivity. Self-reported impulsivity also mediated the effects of different types of stress on drinking behavior. These findings highlight the value of mediation models to examine the pathways through which different types of stress increase drinking behavior. Treatment and prevention strategies should focus on enhancing stress management and self-control. PMID:22376044

  3. Self-reported impulsivity, but not behavioral choice or response impulsivity, partially mediates the effect of stress on drinking behavior.

    PubMed

    Hamilton, Kristen R; Ansell, Emily B; Reynolds, Brady; Potenza, Marc N; Sinha, Rajita

    2013-01-01

    Stress and impulsivity contribute to alcohol use, and stress may also act via impulsivity to increase drinking behavior. Impulsivity represents a multi-faceted construct and self-report and behavioral assessments may effectively capture distinct clinically relevant factors. The present research investigated whether aspects of impulsivity mediate the effect of stress on alcohol use. A community-based sample of 192 men and women was assessed on measures of cumulative stress, alcohol use, self-reported impulsivity, and behavioral choice and response impulsivity. Data were analyzed using regression and bootstrapping techniques to estimate indirect effects of stress on drinking via impulsivity. Cumulative adversity exhibited both direct effects and indirect effects (via self-reported impulsivity) on drinking behavior. Additional models examining specific types of stress indicated direct and indirect effects of trauma and recent life events, and indirect effects of major life events and chronic stressors on drinking behavior. Overall, cumulative stress was associated with increased drinking behavior, and this effect was partially mediated by self-reported impulsivity. Self-reported impulsivity also mediated the effects of different types of stress on drinking behavior. These findings highlight the value of mediation models to examine the pathways through which different types of stress increase drinking behavior. Treatment and prevention strategies should focus on enhancing stress management and self-control.

  4. Reconsidering the link between impulsivity and suicidal behavior.

    PubMed

    Anestis, Michael D; Soberay, Kelly A; Gutierrez, Peter M; Hernández, Theresa D; Joiner, Thomas E

    2014-11-01

    It is widely accepted that suicidal behavior often occurs with little planning. We propose, however, that suicidal behavior is rarely if ever impulsive-that it is too frightening and physically distressing to engage in without forethought-and that suicidal behavior in impulsive individuals is accounted for by painful and fearsome behaviors capable of enhancing their capacity for suicide. We conducted a meta-analysis of the association between trait impulsivity and suicidal behavior and a critical review of research considering the impulsiveness of specific suicide attempts. Meta-analytic results suggest the relationship between trait impulsivity and suicidal behavior is small. Furthermore, studies examining a mediating role of painful and provocative behaviors have uniformly supported our model. Results from our review suggest that researchers have been unable to adequately measure impulsivity of attempts and that measures sensitive to episodic planning must be developed to further our understanding of this phenomenon.

  5. Impulsive action and motivation.

    PubMed

    Frijda, Nico H

    2010-07-01

    This paper explores the way in which emotions are causal determinants of action. It argues that emotional events, as appraised by the individual, elicit changes in motive states (called states of action readiness), which in turn may (or may not) cause action. Actions can be elicited automatically, without prior intention (called impulsive actions), or intentionally. Impulsive actions reflect the simplest and biologically most general form in which emotions can cause action, since they require no reflection, no foresight, and no planning. Impulsive actions are determined conjointly by the nature of action readiness, the affordances perceived in the eliciting event as appraised, and the individual's action repertoire. Those actions from one's repertoire are performed that both match the perceived affordances and the aim of the state of action readiness. Copyright © 2010 Elsevier B.V. All rights reserved.

  6. Ballistic impulse gauge

    DOEpatents

    Ault, S.K.

    1993-12-21

    A gauge for detecting the impulse generated in sample materials by X-rays or other impulse producing mechanisms utilizes a pair of flat annular springs to support a plunger relative to a housing which may itself be supported by a pair of flat annular springs in a second housing. The plunger has a mounting plate mounted on one end and at the other, a position or velocity transducer is mounted. The annular springs consist of an outer ring and an inner ring with at least three arcuate members connecting the outer ring with the inner ring. 4 figures.

  7. Endeavour Impulse Tests

    NASA Image and Video Library

    2003-10-27

    In the Orbiter Processing Facility, Eric Madaras, NASA-Langley Research Center, conducts impulse tests on the right wing leading edge (WLE) of Space Shuttle Endeavour. The tests monitor how sound impulses propagate through the WLE area. The data collected will be analyzed to explore the possibility of adding new instrumentation to the wing that could automatically detect debris or micrometeroid impacts on the Shuttle while in flight. The study is part of the initiative ongoing at KSC and around the agency to return the orbiter fleet to flight status.

  8. Ballistic impulse gauge

    DOEpatents

    Ault, Stanley K.

    1993-01-01

    A gauge for detecting the impulse generated in sample materials by X-rays or other impulse producing mechanisms utilizes a pair of flat annular springs to support a plunger relative to a housing which may itself be supported by a pair of flat annular springs in a second housing. The plunger has a mounting plate mounted on one end and at the other, a position or velocity transducer is mounted. The annular springs consist of an outer ring and an inner ring with at least three arcuate members connecting the outer ring with the inner ring.

  9. A conditioned response as a measure of impulsive-compulsive behaviours in Parkinson's disease.

    PubMed

    Evans, Andrew H; Kettlewell, Jade; McGregor, Sarah; Kotschet, Katya; Griffiths, Robert I; Horne, Malcolm

    2014-01-01

    Parkinson's Disease patients wore a device on the wrist that gave reminders to take levodopa and also measured bradykinesia and dyskinesia. Consumption of medications was acknowledged by placing the thumb on the device. Some patients performed this acknowledgement repeatedly and unconsciously. This study examines whether this behaviour reflected increased impulsivity. Twenty five participants were selected because they had i) excess acknowledgements described above or ii) Impulsive-Compulsive Behaviours or iii) neither of these. A blinded assessor applied clinical scales to measure Impulsive-Compulsive Behaviours, cognition, depression, anxiety and apathy. A Response Ratio, representing the number of acknowledgements/number of doses (expressed as a percentage) was tightly correlated with ratings of Impulsive-Compulsive Behaviours (r² = 0.79) in 19/25 subjects. Some of these patients had dyskinesia, which was higher with extraneous responses than with response indicating medication consumption. Six of the 25 subjects had high Impulsive-Compulsive Behaviour Scores, higher apathy scores, low levels of dyskinesia and normal Response Ratios. Patients without ICB (low RR) also had low dyskinesia levels regardless of the relevance of the response. An elevated Response Ratio is a specific measure of a type of ICB where increased incentive salience is attributed to cues by the presence of high striatal dopamine levels, manifested by high levels of dyskinesia. This study also points to a second form of ICBs which occur in the absence of dyskinesia, has normal Response Ratios and higher apathy scores, and may represent prefrontal pathology.

  10. Selective cocaine-related difficulties in emotional intelligence: relationship to stress and impulse control.

    PubMed

    Fox, Helen C; Bergquist, Keri L; Casey, James; Hong, K Adam; Sinha, Rajita

    2011-01-01

    Emotional Intelligence (EI) comprises the ability to perceive, use, understand, and regulate emotions and may potentially contribute to variability in risk-related factors such as stress perception and impulse control in cocaine dependent individuals. The main objective of the current study is to better define EI in cocaine dependent individuals compared with healthy controls, using the Mayer, Salovey, and Caruso Emotional Intelligence Test (MSCEIT). Secondary analysis investigates the association between EI, IQ factors, perceived stress, and impulse control in both populations. Seventy-two abstinent treatment-seeking cocaine patients and 52 healthy controls were administered the MSCEIT as well as measures of IQ, perceived stress, and impulse control. Findings showed that cocaine dependent participants demonstrated highly selective EI difficulties compared with healthy controls, specifically with regard to higher-level emotional reasoning including the understanding, management, and regulation of emotion. These EI problems were associated with increased perceived stress and impulse control difficulties. IQ was significantly associated with all MSCEIT measures in the cocaine dependent participants, but not controls. Findings indicate that specific aspects of EI may be of clinical importance to cocaine dependent populations, impacting relapse-related factors such as stress dysregulation and impulse control. 

  11. Optimum Three Impulse Trajectory Generator with Patched Conic Trajectory Model

    NASA Technical Reports Server (NTRS)

    Payne, M. H.; Pines, S.; Horsewood, J. L.

    1972-01-01

    Optimal multi-impulse trajectories were investigated as a nominal about which asymptotic expansion was used to obtain approximations of optimal low thrust trajectories. The work consisted of the analysis and description of an optimal 3-impulse trajectory program. A patched-conic trajectory model was specifically designed for compatibility with the subsequent addition of the low thrust expansion approximation.

  12. Effects of a televised two-city safer sex mass media campaign targeting high-sensation-seeking and impulsive-decision-making young adults.

    PubMed

    Zimmerman, Rick S; Palmgreen, Philip M; Noar, Seth M; Lustria, Mia Liza A; Lu, Hung-Yi; Lee Horosewski, Mary

    2007-10-01

    This study evaluates the ability of a safer sex televised public service announcement (PSA) campaign to increase safer sexual behavior among at-risk young adults. Independent, monthly random samples of 100 individuals were surveyed in each city for 21 months as part of an interrupted-time-series design with a control community. The 3-month high-audience-saturation campaign took place in Lexington, KY, with Knoxville, TN, as a comparison city. Messages were especially designed and selected for the target audience (those above the median on a composite sensation-seeking/impulsive-decision-making scale). Data indicate high campaign exposure among the target audience, with 85%-96% reporting viewing one or more PSAs. Analyses indicate significant 5-month increases in condom use, condom-use self-efficacy, and behavioral intentions among the target group in the campaign city with no changes in the comparison city. The results suggest that a carefully targeted, intensive mass media campaign using televised PSAs can change safer sexual behaviors.

  13. Influence of ionisation zone motion in high power impulse magnetron sputtering on angular ion flux and NbO x film growth

    NASA Astrophysics Data System (ADS)

    Franz, Robert; Clavero, César; Kolbeck, Jonathan; Anders, André

    2016-02-01

    The ion energies and fluxes in the high power impulse magnetron sputtering plasma from a Nb target were analysed angularly resolved along the tangential direction of the racetrack. A reactive oxygen-containing atmosphere was used as such discharge conditions are typically employed for the synthesis of thin films. Asymmetries in the flux distribution of the recorded ions as well as their energies and charge states were noticed when varying the angle between mass-energy analyser and target surface. More positively charged ions with higher count rates in the medium energy range of their distributions were detected in +\\mathbf{E}× \\mathbf{B} than in -\\mathbf{E}× \\mathbf{B} direction, thus confirming the notion that ionisation zones (also known as spokes or plasma bunches) are associated with moving potential humps. The motion of the recorded negatively charged high-energy oxygen ions was unaffected. Nb{{\\text{O}}x} thin films at different angles and positions were synthesised and analysed as to their structure and properties in order to correlate the observed plasma properties to the film growth conditions. The chemical composition and the film thickness varied with changing deposition angle, where the latter, similar to the ion fluxes, was higher in +\\mathbf{E}× \\mathbf{B} than in -\\mathbf{E}× \\mathbf{B} direction.

  14. Influence of ionisation zone motion in high power impulse magnetron sputtering on angular ion flux and NbOx film growth

    DOE PAGES

    Franz, Robert; Clavero, César; Kolbeck, Jonathan; ...

    2016-01-21

    Here, the ion energies and fluxes in the high power impulse magnetron sputtering plasma from a Nb target were analysed angularly resolved along the tangential direction of the racetrack. A reactive oxygen-containing atmosphere was used as such discharge conditions are typically employed for the synthesis of thin films. Asymmetries in the flux distribution of the recorded ions as well as their energies and charge states were noticed when varying the angle between mass-energy analyser and target surface. More positively charged ions with higher count rates in the medium energy range of their distributions were detected in +E x B thanmore » in -E x B direction, thus confirming the notion that ionisation zones (also known as spokes or plasma bunches) are associated with moving potential humps. The motion of the recorded negatively charged high-energy oxygen ions was unaffected. NbOx thin films at different angles and positions were synthesised and analysed as to their structure and properties in order to correlate the observed plasma properties to the film growth conditions. The chemical composition and the film thickness varied with changing deposition angle, where the latter, similar to the ion fluxes, was higher in +E x B than in -E x B direction.« less

  15. Influence of ionisation zone motion in high power impulse magnetron sputtering on angular ion flux and NbOx film growth

    SciTech Connect

    Franz, Robert; Clavero, César; Kolbeck, Jonathan; Anders, André

    2016-01-21

    Here, the ion energies and fluxes in the high power impulse magnetron sputtering plasma from a Nb target were analysed angularly resolved along the tangential direction of the racetrack. A reactive oxygen-containing atmosphere was used as such discharge conditions are typically employed for the synthesis of thin films. Asymmetries in the flux distribution of the recorded ions as well as their energies and charge states were noticed when varying the angle between mass-energy analyser and target surface. More positively charged ions with higher count rates in the medium energy range of their distributions were detected in +E x B than in -E x B direction, thus confirming the notion that ionisation zones (also known as spokes or plasma bunches) are associated with moving potential humps. The motion of the recorded negatively charged high-energy oxygen ions was unaffected. NbOx thin films at different angles and positions were synthesised and analysed as to their structure and properties in order to correlate the observed plasma properties to the film growth conditions. The chemical composition and the film thickness varied with changing deposition angle, where the latter, similar to the ion fluxes, was higher in +E x B than in -E x B direction.

  16. Ion Species Fractions in the Far-Field Plume of a High-Specific Impulse Hall Thruster

    NASA Technical Reports Server (NTRS)

    Hofer, Richard R.; Gallimore, Alec D.

    2003-01-01

    An ExB probe was used to measure the ion species fractions of Xe(+), Xe(2+), and Xe(3+) in the far-field plume of the NASA-173Mv2 laboratory-model Hall thruster. The thruster was operated at a constant xenon flow rate of 10 milligrams per second and discharge voltages of 300 to 900 V. The ExB probe was placed two meters downstream of the thruster exit plane on the thruster centerline. At a discharge voltage of 300 V, the species fractions of Xe(2+) and Xe(3+) were lower, but still consistent with, previous Hall thruster studies using other mass analyzers. Over discharge voltages of 300 to 900 V, the Xe(2+) species fractions increased from 0.04 to 0.12 and the Xe(3+) species fraction increased from 0.01 to 0.02.

  17. Relativistic impulse dynamics.

    PubMed

    Swanson, Stanley M

    2011-08-01

    Classical electrodynamics has some annoying rough edges. The self-energy of charges is infinite without a cutoff. The calculation of relativistic trajectories is difficult because of retardation and an average radiation reaction term. By reconceptuallizing electrodynamics in terms of exchanges of impulses rather than describing it by forces and potentials, we eliminate these problems. A fully relativistic theory using photonlike null impulses is developed. Numerical calculations for a two-body, one-impulse-in-transit model are discussed. A simple relationship between center-of-mass scattering angle and angular momentum was found. It reproduces the Rutherford cross section at low velocities and agrees with the leading term of relativistic distinguishable-particle quantum cross sections (Møller, Mott) when the distance of closest approach is larger than the Compton wavelength of the particle. Magnetism emerges as a consequence of viewing retarded and advanced interactions from the vantage point of an instantaneous radius vector. Radiation reaction becomes the local conservation of energy-momentum between the radiating particle and the emitted impulse. A net action is defined that could be used in developing quantum dynamics without potentials. A reinterpretation of Newton's laws extends them to relativistic motion.

  18. Impulse radar studfinder

    DOEpatents

    McEwan, T.E.

    1995-10-10

    An impulse radar studfinder propagates electromagnetic pulses and detects reflected pulses from a fixed range. Unmodulated pulses, about 200 ps wide, are emitted. A large number of reflected pulses are sampled and averaged. Background reflections are subtracted. Reflections from wall studs or other hidden objects are detected and displayed using light emitting diodes. 9 figs.

  19. Impulse radar studfinder

    DOEpatents

    McEwan, Thomas E.

    1995-01-01

    An impulse radar studfinder propagates electromagnetic pulses and detects reflected pulses from a fixed range. Unmodulated pulses, about 200 ps wide, are emitted. A large number of reflected pulses are sampled and averaged. Background reflections are subtracted. Reflections from wall studs or other hidden objects are detected and displayed using light emitting diodes.

  20. Knee and hip joint biomechanics are gender-specific in runners with high running mileage.

    PubMed

    Gehring, D; Mornieux, G; Fleischmann, J; Gollhofer, A

    2014-02-01

    Female runners are reported to be more prone to develop specific knee joint injuries than males. It has been suggested that increased frontal plane joint loading might be related to the incidence of these knee injuries in running. The purpose of this study was to evaluate if frontal plane knee and hip joint kinematics and kinetics are gender-specific in runners with high mileage. 3D-kinematics and kinetics were recorded from 16 female and 16 male runners at a speed of 3 m/s, 4 m/s, and 5 m/s. Frontal plane joint angles and joint moments were ascertained and compared between genders among speed conditions. Across all speed conditions, females showed increased hip adduction and reduced knee adduction angles compared to males (p < 0.003). The initial peak in the hip adduction moment was enhanced in females (p = 0.003). Additionally, the hip adduction impulse showed a trend towards an increase in females at slow running speed (p = 0.07). Hip and knee frontal plane joint kinematics are gender-specific. In addition, there are indications that frontal plane joint loading is increased in female runners. Future research should focus on the relationship of these observations regarding overuse running injuries.

  1. Impulse Flashover Tests at Edgar Beauchamp High Voltage Test Facility, Dixon, California, in Support of Cutler Insulator Failure Investigation

    DTIC Science & Technology

    2006-07-01

    tests showed that flashover occurred along the surface of the insulator when the voltage rises very fast (high dV/dt). Flashover along the surface is...was melted at these current levels. Flashovers along the surface initiated from the region around the triple point at the ground end of the insulator...insulator surface at high values of dV/dt. The surface flashovers seemed to initiate from the triple point at the ground end of the insulator body and

  2. Combining a molecular modelling approach with direct current and high power impulse magnetron sputtering to develop new TiO2 thin films for antifouling applications

    NASA Astrophysics Data System (ADS)

    Guillot, Jérôme; Lecoq, Elodie; Duday, David; Puhakka, Eini; Riihimäki, Markus; Keiski, Riitta; Chemin, Jean-Baptiste; Choquet, Patrick

    2015-04-01

    The accumulation of crystallization deposits at the surface of heat exchangers results in the increase of the heat transfer resistance and a drastic loss of efficiency. Coating surfaces with a thin film can limit the scale-surface adhesion force and thus the fouling process. This study compares the efficiency of TiO2 layers exhibiting various crystalline planes and microstructures to reduce the kinetic of fouling. Molecular modelling with density functional theory is first carried out to determine the energy of CaCO3 deposition on anatase (1 0 1), (0 0 4), and (2 0 0) surfaces as well as on a rutile (1 0 1) one. TiO2 thin films (thickness < 1 μm) are then synthesized by direct current and high power impulse magnetron sputtering (dcMS and HiPIMS respectively) in order to tune their crystallinity and microstructure. Lastly, the induction time to grow CaCO3 crystals at the surface of such materials is determined. Comparing the modelling and fouling results allows to draw general trends on the potential anti-scaling properties of TiO2 crystallized under various forms. Until now, such a comparison combining a theoretical approach with experimental fouling tests has never been reported in the literature.

  3. Improving optical properties of silicon nitride films to be applied in the middle infrared optics by a combined high-power impulse/unbalanced magnetron sputtering deposition technique.

    PubMed

    Liao, Bo-Huei; Hsiao, Chien-Nan

    2014-02-01

    Silicon nitride films are prepared by a combined high-power impulse/unbalanced magnetron sputtering (HIPIMS/UBMS) deposition technique. Different unbalance coefficients and pulse on/off ratios are applied to improve the optical properties of the silicon nitride films. The refractive indices of the Si3N4 films vary from 2.17 to 2.02 in the wavelength ranges of 400-700 nm, and all the extinction coefficients are smaller than 1×10(-4). The Fourier transform infrared spectroscopy and x-ray diffractometry measurements reveal the amorphous structure of the Si3N4 films with extremely low hydrogen content and very low absorption between the near IR and middle IR ranges. Compared to other deposition techniques, Si3N4 films deposited by the combined HIPIMS/UBMS deposition technique possess the highest refractive index, the lowest extinction coefficient, and excellent structural properties. Finally a four-layer coating is deposited on both sides of a silicon substrate. The average transmittance from 3200 to 4800 nm is 99.0%, and the highest transmittance is 99.97% around 4200 nm.

  4. A study of the oxygen dynamics in a reactive Ar/O2 high power impulse magnetron sputtering discharge using an ionization region model

    NASA Astrophysics Data System (ADS)

    Lundin, D.; Gudmundsson, J. T.; Brenning, N.; Raadu, M. A.; Minea, T. M.

    2017-05-01

    The oxygen dynamics in a reactive Ar/O2 high power impulse magnetron sputtering discharge has been studied using a new reactive ionization region model. The aim has been to identify the dominating physical and chemical reactions in the plasma and on the surfaces of the reactor affecting the oxygen plasma chemistry. We explore the temporal evolution of the density of the ground state oxygen molecule O 2 ( X 1 Σg - ) , the singlet metastable oxygen molecules O 2 ( a 1 Δ g ) and O 2 ( b 1 Σ g ) , the oxygen atom in the ground state O(3P), the metastable oxygen atom O(1D), the positive ions O2 + and O+, and the negative ion O-. We furthermore investigate the reaction rates for the gain and loss of these species. The density of atomic oxygen increases significantly as we move from the metal mode to the transition mode, and finally into the compound (poisoned) mode. The main gain rate responsible for the increase is sputtering of atomic oxygen from the oxidized target. Both in the poisoned mode and in the transition mode, sputtering makes up more than 80% of the total gain rate for atomic oxygen. We also investigate the possibility of depositing stoichiometric TiO2 in the transition mode.

  5. Drifting localization of ionization runaway: Unraveling the nature of anomalous transport in high power impulse magnetron sputtering

    SciTech Connect

    Anders, Andre; Ni, Pavel; Rauch, Albert

    2012-03-01

    The plasma over a magnetron's erosion ''racetrack'' is not azimuthally uniform but concentrated in distinct dense ionization zones which move in the ExB direction with about 10% of the electron ExB/B{sup 2} drift velocity. The ionization zones are investigated with a gated camera working in concert with a streak camera for Al, Nb, Cu, and W targets in Ar or Kr background gas. It is found that each ionization zone has a high plasma density edge, which is the origin of a plasma-generating electron jet leaving the target zone. Each region of strong azimuthal plasma density gradient generates an azimuthal electric field, which promotes the escape of magnetized electrons and the formation of electron jets and plasma flares. The phenomena are proposed to be caused by an ionization instability where each dense plasma zone exhibits a high stopping power for drifting high energy electrons, thereby enhancing itself.

  6. Objects, decision considerations and self-image in men's and women's impulse purchases.

    PubMed

    Dittmar, H; Beattie, J; Friese, S

    1996-09-01

    Current theories in economics, marketing, and psychology fail to explain underlying reasons for impulse buying and, crucially, why certain goods (e.g., clothes) are bought impulsively more than others (e.g., basic kitchen equipment). We propose and examine a social psychological model, which predicts that people impulse buy to acquire material symbols of personal and social identity. We predict that consumers will differ systematically in the goods they buy on impulse, and in their reasons for doing so, depending on their attitudes towards shopping, and also along important social categories, such as gender. Specifically, our theoretical model-drawing on a social constructionist model of material possessions (e.g., Dittmar, 1992) and symbolic self-completion theory (e.g. Wicklund and Gollwitzer, 1982)-leads to three sets of hypotheses: (i) some consumer durables are more likely to be bought on impulse than others, and there may be gender differences in object choices, (ii) differences will emerge in the buying considerations (e.g., functional, emotional, symbolic) that are used for impulse and planned buying, and (iii) magnitude of self-discrepancies will predict relative impulse buying frequency and the buying considerations used, if the individual uses consumption as a self-completion strategy. These predictions were expected to hold particularly strongly for individuals high in compulsive shopping tendencies. We test our model in a questionnaire study with a sample of British consumers (n = 61). The results lend support to all three sets of hypotheses. The implications of these findings are discussed with respect to economic and consumer theory, and the treatment offered to the increasing number of 'addicted' shoppers.

  7. Impulsivity and Aggression in Female BPD and ADHD Patients: Association with ACC Glutamate and GABA Concentrations.

    PubMed

    Ende, Gabriele; Cackowski, Sylvia; Van Eijk, Julia; Sack, Markus; Demirakca, Traute; Kleindienst, Nikolaus; Bohus, Martin; Sobanski, Esther; Krause-Utz, Annegret; Schmahl, Christian

    2016-01-01

    Borderline personality disorder (BPD) and attention-deficit-hyperactivity disorder (ADHD) are both characterized by high impulsivity and difficulties in controlling anger and aggression. In BPD, comorbid ADHD may further increase impulsivity. For both disorders, altered MR spectroscopy levels of the neurotransmitters glutamate and GABA as well as some correlations with impulsivity were previously reported. The objective of this study was to investigate the neurotransmitters glutamate and GABA in relation to impulsivity and aggression as expressed in the anterior cingulate cortex (ACC) in groups of female patients with BPD and ADHD, respectively. Associations of glutamate and GABA levels with further BPD (symptom severity) and ADHD aspects (hyperactivity and inattention) were exploratively evaluated. 1H MR spectra were acquired at 3T to determine glutamate to total creatine ratios (Glu/tCr) and GABA levels from the ACC in a BPD group (n=26), an ADHD group (n=22), and a healthy control (HC) group (n=30); all participants were females. Both patient groups showed higher scores on self-reported impulsivity, anger, and aggression compared with HCs. ACC GABA levels were significantly lower in ADHD than HC. Although measures of impulsivity were positively related to glutamate and negatively to GABA, for aggression only a negative correlation with GABA could be demonstrated. These data provide human in vivo evidence for the role of ACC Glu/tCr and GABA in impulsivity and aggression. If distinct associations of Glu/tCr and GABA for BPD and ADHD can be confirmed in future studies, this might yield implications for more specific pharmacological treatments.

  8. Impulsivity and Aggression in Female BPD and ADHD Patients: Association with ACC Glutamate and GABA Concentrations

    PubMed Central

    Ende, Gabriele; Cackowski, Sylvia; Van Eijk, Julia; Sack, Markus; Demirakca, Traute; Kleindienst, Nikolaus; Bohus, Martin; Sobanski, Esther; Krause-Utz, Annegret; Schmahl, Christian

    2016-01-01

    Borderline personality disorder (BPD) and attention-deficit-hyperactivity disorder (ADHD) are both characterized by high impulsivity and difficulties in controlling anger and aggression. In BPD, comorbid ADHD may further increase impulsivity. For both disorders, altered MR spectroscopy levels of the neurotransmitters glutamate and GABA as well as some correlations with impulsivity were previously reported. The objective of this study was to investigate the neurotransmitters glutamate and GABA in relation to impulsivity and aggression as expressed in the anterior cingulate cortex (ACC) in groups of female patients with BPD and ADHD, respectively. Associations of glutamate and GABA levels with further BPD (symptom severity) and ADHD aspects (hyperactivity and inattention) were exploratively evaluated. 1H MR spectra were acquired at 3T to determine glutamate to total creatine ratios (Glu/tCr) and GABA levels from the ACC in a BPD group (n=26), an ADHD group (n=22), and a healthy control (HC) group (n=30); all participants were females. Both patient groups showed higher scores on self-reported impulsivity, anger, and aggression compared with HCs. ACC GABA levels were significantly lower in ADHD than HC. Although measures of impulsivity were positively related to glutamate and negatively to GABA, for aggression only a negative correlation with GABA could be demonstrated. These data provide human in vivo evidence for the role of ACC Glu/tCr and GABA in impulsivity and aggression. If distinct associations of Glu/tCr and GABA for BPD and ADHD can be confirmed in future studies, this might yield implications for more specific pharmacological treatments. PMID:26040503

  9. Reflective and impulsive determinants of social behavior.

    PubMed

    Strack, Fritz; Deutsch, Roland

    2004-01-01

    This article describes a 2-systems model that explains social behavior as a joint function of reflective and impulsive processes. In particular, it is assumed that social behavior is controlled by 2 interacting systems that follow different operating principles. The reflective system generates behavioral decisions that are based on knowledge about facts and values, whereas the impulsive system elicits behavior through associative links and motivational orientations. The proposed model describes how the 2 systems interact at various stages of processing, and how their outputs may determine behavior in a synergistic or antagonistic fashion. It extends previous models by integrating motivational components that allow more precise predictions of behavior. The implications of this reflective-impulsive model are applied to various phenomena from social psychology and beyond. Extending previous dual-process accounts, this model is not limited to specific domains of mental functioning and attempts to integrate cognitive, motivational, and behavioral mechanisms.

  10. Auto-programmable impulse neural circuits

    NASA Technical Reports Server (NTRS)

    Watula, D.; Meador, J.

    1990-01-01

    Impulse neural networks use pulse trains to communicate neuron activation levels. Impulse neural circuits emulate natural neurons at a more detailed level than that typically employed by contemporary neural network implementation methods. An impulse neural circuit which realizes short term memory dynamics is presented. The operation of that circuit is then characterized in terms of pulse frequency modulated signals. Both fixed and programmable synapse circuits for realizing long term memory are also described. The implementation of a simple and useful unsupervised learning law is then presented. The implementation of a differential Hebbian learning rule for a specific mean-frequency signal interpretation is shown to have a straightforward implementation using digital combinational logic with a variation of a previously developed programmable synapse circuit. This circuit is expected to be exploited for simple and straightforward implementation of future auto-adaptive neural circuits.

  11. Association between Impulsivity and Weight Status in a General Population

    PubMed Central

    Bénard, Marc; Camilleri, Géraldine M.; Etilé, Fabrice; Méjean, Caroline; Bellisle, France; Reach, Gérard; Hercberg, Serge; Péneau, Sandrine

    2017-01-01

    The objective of this study is to examine the association between impulsivity and weight status in a large sample of the adult general population in France, and the influence of gender on this relationship. A total of 11,929 men and 39,114 women participating in the NutriNet-Santé cohort were selected in this cross-sectional analysis. The Barratt Impulsiveness Scale (BIS-11) was used to assess impulsivity. Weight and height were self-reported. The association between impulsivity and BMI was estimated using logistic regressions adjusted for socio-demographic and lifestyle factors. Individuals with high impulsivity levels (BIS-11 total score >71) were more likely to be obese (Odds Ratio (OR) = 1.80, 95% Confidence Interval (CI): 1.39, 2.33 in men; OR = 1.30, 95% CI: 1.15, 1.48 in women) compared to individuals in the average range of impulsivity. The strongest associations between impulsivity and obesity were observed in men, where highly impulsive participants were more likely to be class III obese (BMI > 40 kg/m2) (OR = 3.57, 95% CI: 1.86, 6.85). This large sample analysis supports the existence of a relationship between impulsivity and weight status and the importance of psychological factors in the prevention of obesity. PMID:28257032

  12. Neural substrates of time perception and impulsivity.

    PubMed

    Wittmann, Marc; Simmons, Alan N; Flagan, Taru; Lane, Scott D; Wackermann, Jiří; Paulus, Martin P

    2011-08-11

    Several studies provide empirical evidence for the association between impulsivity and time perception. However, little is known about the neural substrates underlying this function. This investigation examined the influence of impulsivity on neural activation patterns during the encoding and reproduction of intervals with durations of 3, 9 and 18s using event-related functional magnetic resonance imaging (fMRI). Twenty-seven subjects participated in this study, including 15 high impulsive subjects that were classified based on their self-rating. FMRI activation during the duration reproduction task was correlated with measures of two self-report questionnaires related to the concept of impulsivity (Barratt Impulsiveness Scale, BIS; Zimbardo Time Perspective Inventory, ZTPI). Behaviorally, those individuals who under-reproduced temporal intervals also showed lower scores on the ZTPI future perspective subscale and higher scores on the BIS. FMRI activation revealed an accumulating pattern of neural activity peaking at the end of the 9- and 18-s intervals within right posterior insula. Activations of brain regions during the reproduction phase of the timing task, such as those related to motor execution as well as to the 'core control network' - encompassing the inferior frontal and medial frontal cortices, the anterior insula as well as the inferior parietal cortex - were significantly correlated with reproduced duration, as well as with BIS and ZTPI subscales. In particular, the greater activation in these regions the shorter were the reproduced intervals, the more impulsive was an individual and the less pronounced the future perspective. Activation in the core control network, thus, may form a biological marker for cognitive time management and for impulsiveness.

  13. Neural substrates of time perception and impulsivity

    PubMed Central

    Wittmann, Marc; Simmons, Alan N.; Flagan, Taru; Lane, Scott D.; Wackermann, Jiří; Paulus, Martin P.

    2011-01-01

    Several studies provide empirical evidence for the association between impulsivity and time perception. However, little is known about the neural substrates underlying this function. This investigation examined the influence of impulsivity on neural activation patterns during the encoding and reproduction of intervals with durations of 3, 9 and 18 seconds using event-related functional magnetic resonance imaging (fMRI). Twenty-seven subjects participated in this study, including 15 high impulsive subjects that were classified based on their self-rating. FMRI activation during the duration reproduction task was correlated with measures of two self-report questionnaires related to the concept of impulsivity (Barratt Impulsiveness Scale, BIS; Zimbardo Time Perspective Inventory, ZTPI). Behaviorally, those individuals who under-reproduced temporal intervals also showed lower scores on the ZTPI future perspective subscale and higher scores on the BIS. FMRI activation revealed an accumulating pattern of neural activity peaking at the end of the 9- and 18-s interval within right posterior insula. Activations of brain regions during the reproduction phase of the timing task, such as those related to motor execution as well as to the ‘core control network’ – encompassing the inferior frontal and medial frontal cortex, the anterior insula as well as the inferior parietal cortex – were significantly correlated with reproduced duration, as well as with BIS and ZTPI subscales. In particular, the greater activation in these regions the shorter were the reproduced intervals, the more impulsive was an individual and the less pronounced the future perspective. Activation in the core control network, thus, may form a biological marker for cognitive time management and for impulsiveness. PMID:21763642

  14. High School Educational Specifications: Facilities Planning Standards. Edition I.

    ERIC Educational Resources Information Center

    Jefferson County School District R-1, Denver, CO.

    The Jefferson County School District (Colorado) has developed a manual of high school specifications for Design Advisory Groups and consultants to use for planning and designing the district's high school facilities. The specifications are provided to help build facilities that best meet the educational needs of the students to be served.…

  15. Annoyance of helicopter impulsive noise

    NASA Technical Reports Server (NTRS)

    Dambra, F.; Damongeot, A.

    1978-01-01

    Psychoacoustic studies of helicopter impulsive noise were conducted in order to qualify additional annoyance due to this feature and to develop physical impulsiveness descriptors to develop impulsivity correction methods. The currently proposed descriptors and methods of impulsiveness correction are compared using a multilinear regression analysis technique. It is shown that the presently recommended descriptor and correction method provides the best correlation with the subjective evaluations of real helicopter impulsive noises. The equipment necessary for data processing in order to apply the correction method is discussed.

  16. Drifting localization of ionization runaway: Unraveling the nature of anomalous transport in high power impulse magnetron sputtering

    SciTech Connect

    Ni, Pavel; Rauch, Albert

    2011-12-04

    The plasma over the magnetron’s erosion “racetrack” is not azimuthally uniform but concentrated in distinct dense plasma zones which move in the {vector E}×{vector B} direction with about 10% of the electrons’ {vector E}×{vector B}/B{sup 2} drift velocity. The plasma zones are investigated with a gated camera working in concert with a streak camera for Al, Nb, Cu, and W targets in Ar or Kr background gas. It is found that each plasma zone has a high density edge which is the origin of a plasma-generating electron jet leaving the target zone. Each region of strong azimuthal density gradient generates an azimuthal electric field which promotes the escape of magnetized electrons and the formation of electron jets and plasma flares. The phenomena are proposed to be caused by an ionization instability where each dense plasma zone exhibits a high stopping power for drifting high energy electrons, thereby enhancing itself.

  17. Cocaine self-administration punished by i.v. histamine in rat models of high and low drug abuse vulnerability: effects of saccharin preference, impulsivity, and sex.

    PubMed

    Holtz, Nathan A; Anker, Justin J; Regier, Paul S; Claxton, Alex; Carroll, Marilyn E

    2013-10-02

    A key feature of substance use disorders is continued drug consumption despite aversive consequences. This has been modeled in the animal laboratory by pairing drug self-administration with electric shock, thereby punishing drug intake (Deroche-Gamonet et al. 2004). In the present experiments, we examined the effects of punishment on i.v. cocaine self-administration by adding histamine to the cocaine solution with three different animal models of high and low vulnerability to drug abuse: rats selectively bred for high (HiS) and low (LoS) saccharin consumption, rats selected for high (HiI) and low (LoI) impulsivity, and sex differences. Animals were allowed to self-administer cocaine (0.4 mg/kg/infusion) to establish a baseline of operant responding. Histamine (4.0mg/kg/infusion) was then added directly into the cocaine solution and its consequent effects on self-administration were compared to baseline. The histamine+cocaine solution was then replaced with a cocaine-only solution, and the rats' operant responding was again compared to baseline. Concurrent histamine exposure was effective in reducing cocaine consumption in all groups of rats; however, LoS and female rats took longer to return to baseline levels of cocaine consumption after histamine was removed compared to HiS and male rats. These data suggest that the reduction of drug self-administration by aversive consequences may differ in groups that vary in drug use vulnerability . Such results may inform pharmacological strategies that enhance the negative aspects of drug consumption. © 2013.

  18. Online and live regular poker players: Do they differ in impulsive sensation seeking and gambling practice?

    PubMed

    Barrault, Servane; Varescon, Isabelle

    2016-03-01

    Background and aims Online gambling appears to have special features, such as anonymity, speed of play and permanent availability, which may contribute to the facilitation and increase in gambling practice, potentially leading to problem gambling. The aims of this study were to assess sociodemographic characteristics, gambling practice and impulsive sensation seeking among a population of regular poker players with different levels of gambling intensity and to compare online and live players. Methods 245 regular poker players (180 online players and 65 live players) completed online self-report scales assessing sociodemographic data, pathological gambling (SOGS), gambling practice (poker questionnaire) and impulsive sensation seeking (ImpSS). We used SOGS scores to rank players according to the intensity of their gambling practice (non-pathological gamblers, problem gamblers and pathological gamblers). Results All poker players displayed a particular sociodemographic profile: they were more likely to be young men, executives or students, mostly single and working full-time. Online players played significantly more often whereas live players reported significantly longer gambling sessions. Sensation seeking was high across all groups, whereas impulsivity significantly distinguished players according to the intensity of gambling. Discussion Our results show the specific profile of poker players. Both impulsivity and sensation seeking seem to be involved in pathological gambling, but playing different roles. Sensation seeking may determine interest in poker whereas impulsivity may be involved in pathological gambling development and maintenance. Conclusions This study opens up new research perspectives and insights into preventive and treatment actions for pathological poker players.

  19. Online and live regular poker players: Do they differ in impulsive sensation seeking and gambling practice?

    PubMed Central

    Barrault, Servane; Varescon, Isabelle

    2016-01-01

    Background and aims Online gambling appears to have special features, such as anonymity, speed of play and permanent availability, which may contribute to the facilitation and increase in gambling practice, potentially leading to problem gambling. The aims of this study were to assess sociodemographic characteristics, gambling practice and impulsive sensation seeking among a population of regular poker players with different levels of gambling intensity and to compare online and live players. Methods 245 regular poker players (180 online players and 65 live players) completed online self-report scales assessing sociodemographic data, pathological gambling (SOGS), gambling practice (poker questionnaire) and impulsive sensation seeking (ImpSS). We used SOGS scores to rank players according to the intensity of their gambling practice (non-pathological gamblers, problem gamblers and pathological gamblers). Results All poker players displayed a particular sociodemographic profile: they were more likely to be young men, executives or students, mostly single and working full-time. Online players played significantly more often whereas live players reported significantly longer gambling sessions. Sensation seeking was high across all groups, whereas impulsivity significantly distinguished players according to the intensity of gambling. Discussion Our results show the specific profile of poker players. Both impulsivity and sensation seeking seem to be involved in pathological gambling, but playing different roles. Sensation seeking may determine interest in poker whereas impulsivity may be involved in pathological gambling development and maintenance. Conclusions This study opens up new research perspectives and insights into preventive and treatment actions for pathological poker players. PMID:28092187

  20. Choice impulsivity: Definitions, measurement issues, and clinical implications.

    PubMed

    Hamilton, Kristen R; Mitchell, Marci R; Wing, Victoria C; Balodis, Iris M; Bickel, Warren K; Fillmore, Mark; Lane, Scott D; Lejuez, C W; Littlefield, Andrew K; Luijten, Maartje; Mathias, Charles W; Mitchell, Suzanne H; Napier, T Celeste; Reynolds, Brady; Schütz, Christian G; Setlow, Barry; Sher, Kenneth J; Swann, Alan C; Tedford, Stephanie E; White, Melanie J; Winstanley, Catharine A; Yi, Richard; Potenza, Marc N; Moeller, F Gerard

    2015-04-01

    Impulsivity critically relates to many psychiatric disorders. Given the multifaceted construct that impulsivity represents, defining core aspects of impulsivity is vital for the assessment and understanding of clinical conditions. Choice impulsivity (CI), involving the preferential selection of smaller sooner rewards over larger later rewards, represents one important type of impulsivity. The International Society for Research on Impulsivity (InSRI) convened to discuss the definition and assessment of CI and provide recommendations regarding measurement across species. Commonly used preclinical and clinical CI behavioral tasks are described, and considerations for each task are provided to guide CI task selection. Differences in assessment of CI (self-report, behavioral) and calculating CI indices (e.g., area-under-the-curve, indifference point, and steepness of discounting curve) are discussed along with properties of specific behavioral tasks used in preclinical and clinical settings. The InSRI group recommends inclusion of measures of CI in human studies examining impulsivity. Animal studies examining impulsivity should also include assessments of CI and these measures should be harmonized in accordance with human studies of the disorders being modeled in the preclinical investigations. The choice of specific CI measures to be included should be based on the goals of the study and existing preclinical and clinical literature using established CI measures.

  1. Choice Impulsivity: Definitions, Measurement Issues, and Clinical Implications

    PubMed Central

    Hamilton, Kristen R.; Mitchell, Marci R.; Wing, Victoria C.; Balodis, Iris M.; Bickel, Warren K.; Fillmore, Mark; Lane, Scott D.; Lejuez, C. W.; Littlefield, Andrew K.; Luijten, Maartje; Mathias, Charles W.; Mitchell, Suzanne H.; Napier, T. Celeste; Reynolds, Brady; Schütz, Christian G.; Setlow, Barry; Sher, Kenneth J.; Swann, Alan C.; Tedford, Stephanie E.; White, Melanie J.; Winstanley, Catharine A.; Yi, Richard; Potenza, Marc N.; Moeller, F. Gerard

    2015-01-01

    Background Impulsivity critically relates to many psychiatric disorders. Given the multi-faceted construct that impulsivity represents, defining core aspects of impulsivity is vital for the assessment and understanding of clinical conditions. Choice impulsivity (CI), involving the preferential selection of smaller sooner rewards over larger later rewards, represents one important type of impulsivity. Method The International Society for Research on Impulsivity (InSRI) convened to discuss the definition and assessment of CI and provide recommendations regarding measurement across species. Results Commonly used preclinical and clinical CI behavioral tasks are described, and considerations for each task are provided to guide CI task selection. Differences in assessment of CI (self-report, behavioral) and calculating CI indices (e.g., area-under-the-curve, indifference point, steepness of discounting curve) are discussed along with properties of specific behavioral tasks used in preclinical and clinical settings. Conclusions The InSRI group recommends inclusion of measures of CI in human studies examining impulsivity. Animal studies examining impulsivity should also include assessments of CI and these measures should be harmonized in accordance with human studies of the disorders being modeled in the preclinical investigations. The choice of specific CI measures to be included should be based on the goals of the study and existing preclinical and clinical literature using established CI measures. PMID:25867841

  2. Validity of proposed DSM-5 ADHD impulsivity symptoms in children.

    PubMed

    Ünsel Bolat, Gül; Ercan, Eyüp Sabri; Salum, Giovanni Abrahão; Bilaç, Öznur; Massuti, Rafael; Uysal Özaslan, Taciser; Bolat, Hilmi; Rohde, Luis Augusto

    2016-10-01

    The American Psychiatric Association (APA) working group on Attention-Deficit/Hyperactivity Disorder (ADHD) proposed the inclusion of four new impulsivity symptoms. However, they were not included in DSM-5 due to the lack of sufficient evidence. The aim of this study is to investigate the performance of the proposed four ADHD impulsivity symptoms with respect to: (a) ADHD factor structure; (b) performance in predicting clinical impairment; (c) specificity for ADHD diagnosis and (d) best symptomatic threshold to predict clinical impairment. The sample comprised 416 children (31 ADHD subjects according to both DSM-IV and proposed DSM-5, 20 ADHD subjects according to just one diagnostic system and 365 controls) from 12 schools. Diagnoses were derived using semi-structured interviews and ADHD rating scales. Results from confirmatory factor analysis indicate that addition of the four new impulsivity items provided a slightly better factor structure if compared to models including only 18 items. Regression analyses showed that only one of the new impulsivity symptoms (impatient) was part of the list of best predictors of impairment. None of the four new impulsivity items was specifically associated with ADHD diagnosis. The best cutoff point in the hyperactivity/impulsivity dimension for predicting impairment did not change significantly. Overall, our findings suggest that the determination on how to best capture impulsivity dimension as part of the ADHD construct needs more investigation and that there is not enough evidence to include these four assessed impulsivity symptoms as part of the ADHD criteria.

  3. Impulsive for life? The nature of long-term impulsivity in domestic dogs.

    PubMed

    Riemer, Stefanie; Mills, Daniel S; Wright, Hannah

    2014-05-01

    Individual differences in impulsivity occur at a cognitive and/or behavioural level and are associated with differing life outcomes. However, there is a lack of empirical evidence to support the long-term stability of these characteristics in non-human animals. This study reports on the stability of convergent measures of impulsivity in domestic dogs assessed more than 6 years apart. Measures were (1) owner assessment by means of a questionnaire, the validated 'Dog Impulsivity Assessment Scale' (DIAS) and (2) dogs' performance in a delayed reward choice test. Dogs had 15-min free access to two food dispensers, one dispensing a piece of food immediately, the other dispensing three pieces after a delay, which increased by 1 s every other time the dogs sampled it. Maximum delay reached in this task reflects decision-making, or cognitive impulsivity, whereas the rate of extra presses on the delayed reward device during the delay can be considered as a measure of motor or behavioural impulsivity. DIAS scores were strongly and significantly correlated across years. The maximum delay reached in the behaviour test was also highly stable, whereas paw-pressing rate was uncorrelated between the years. These results demonstrate that cognitive but not motor impulsivity is highly consistent over time in dogs.

  4. Micropower impulse radar imaging

    SciTech Connect

    Hall, M.S.

    1995-11-01

    From designs developed at the Lawrence Livermore National Laboratory (LLNL) in radar and imaging technologies, there exists the potential for a variety of applications in both public and private sectors. Presently tests are being conducted for the detection of buried mines and the analysis of civil structures. These new systems use a patented ultra-wide band (impulse) radar technology known as Micropower Impulse Radar (GPR) imaging systems. LLNL has also developed signal processing software capable of producing 2-D and 3-D images of objects embedded in materials such as soil, wood and concrete. My assignment while at LLNL has focused on the testing of different radar configurations and applications, as well as assisting in the creation of computer algorithms which enable the radar to scan target areas of different geometeries.

  5. The Relationship between Impulsivity and Problem Gambling in Adolescence

    PubMed Central

    Secades-Villa, Roberto; Martínez-Loredo, Victor; Grande-Gosende, Aris; Fernández-Hermida, José R.

    2016-01-01

    Gambling has become one of the most frequently reported addictive behaviors among young people. Understanding risk factors associated with the onset or maintenance of gambling problems in adolescence has implications for its prevention and treatment. The main aim of the present study was to examine the potential relationships between impulsivity and problem gambling in adolescence. Participants were 874 high school students (average age: 15 years old) who were surveyed to provide data on gambling and impulsivity. Self-reported gambling behavior was assessed using the South Oaks Gambling Screen – Revised for Adolescents (SOGS-RA) and impulsivity was measured using the Impulsive Sensation Seeking Questionnaire (ZKPQ), the Barratt Impulsiveness Scale (BIS-11-A), and a delay discounting task. The data were analyzed using both a prospective-longitudinal and a cross-sectional design. In the longitudinal analyses, results showed that the impulsivity subscale of the ZKPQ increased the risk of problem gambling (p = 0.003). In the cross-sectional analyses, all the impulsivity measures were higher in at-risk/problem gamblers than in non-problem gamblers (p = 0.04; 0.03; and 0.01, respectively). These findings further support the relationship between impulsivity and gambling in adolescence. Moreover, our findings suggest a bidirectional relationship between impulsivity and problem gambling in adolescence. These results have consequences for the development of prevention and treatment programs for adolescents with gambling problems. PMID:28008322

  6. Impulsive actions and choices in laboratory animals and humans: effects of high vs. low dopamine states produced by systemic treatments given to neurologically intact subjects

    PubMed Central

    D’Amour-Horvat, Valérie; Leyton, Marco

    2014-01-01

    Increases and decreases in dopamine (DA) transmission have both been suggested to influence reward-related impulse-control. The present literature review suggests that, in laboratory animals, the systemic administration of DA augmenters preferentially increases susceptibility to premature responding; with continued DA transmission, reward approach behaviors are sustained. Decreases in DA transmission, in comparison, diminish the appeal of distal and difficult to obtain rewards, thereby increasing susceptibility to temporal discounting and other forms of impulsive choice. The evidence available in humans is not incompatible with this model but is less extensive. PMID:25566001

  7. Dynamics of processes during the deposition of ZrO2 films by controlled reactive high-power impulse magnetron sputtering: A modelling study

    NASA Astrophysics Data System (ADS)

    Kozák, Tomáš; Vlček, Jaroslav

    2017-07-01

    A time-dependent parametric model was applied to controlled reactive high-power impulse magnetron sputtering (HiPIMS) depositions of stoichiometric ZrO2 films, carried out in our laboratories, (i) to clarify the complicated dynamics of the processes on the target and substrate surfaces during voltage pulses, and (ii) to corroborate the importance of the O2 inlet configuration (position and direction) which strongly affects the O2 dissociation in the discharge and the chemisorption flux of oxygen atoms and molecules onto the substrate. The repetition frequency was 500 Hz at the deposition-averaged target power densities of 25 Wcm-2, being close to a target power density applicable in industrial HiPIMS systems, and 50 Wcm-2 with a pulse-averaged target power density up to 2 kWcm-2. The pulse duration was 50 μs. For the experimental conditions with the to-substrate O2 inlets, the deposition-averaged target power density of 50 Wcm-2, and the oxygen partial pressure of 0.05 Pa (being close to the mean value during controlled depositions), our model predicts a low compound fraction, changing between 8% and 12%, in the target surface layer at an almost constant high compound fraction, changing between 92% and 93%, in the substrate surface layer during the pulse period (2000 μs). The calculated deposition rate of 89 nm/min for these films is in good agreement with the measured value of 80 nm/min achieved for optically transparent stoichiometric ZrO2 films prepared under these conditions.

  8. Measurement and modeling of plasma parameters in reactive high-power impulse magnetron sputtering of Ti in Ar/O2 mixtures

    NASA Astrophysics Data System (ADS)

    Čada, M.; Lundin, D.; Hubička, Z.

    2017-05-01

    A reactive high-power impulse magnetron sputtering (HiPIMS) process using a titanium target in a mixture of Ar/O2 has been investigated for different modes of operation including pure argon, metallic, transition, and compound mode. The trends and changes in the plasma density ne and the effective electron temperature Teff, have been measured by the time-resolved Langmuir probe technique. The same experimental process conditions have also been studied using a recently developed reactive ionization region model (R-IRM), making it possible to compare the acquired experimental results with the model results. It was found that trends in the plasma density and mean electron energy as measured by the Langmuir probe are in good agreement with the results obtained from the R-IRM model for different pulse discharge current densities. The effective electron temperature generally increases with an increasing oxygen flow rate. It is likely due to a reduction of sputtered Ti, due to compound formation on the target, which forces the discharge to increase the electron energy to increase the ionization rate of the process gas (Ar/O2) to maintain a high HiPIMS discharge current. Small variations in the plasma density were detected between the middle part of the plasma pulse as compared to the end of the plasma pulse, when transitioning from the metal mode to the poisoned mode. It is found that the time-evolution of the electron density is rather well correlated with the discharge current waveform. On the other hand, the mean electron energy did not change significantly between the middle and the end of the plasma pulse. For the lower pulse discharge current, both the model and experimental data have shown a slight increase in the plasma density with increasing O2 mass flow rate.

  9. Impulsivity trait in the early symptomatic BACHD transgenic rat model of Huntington disease.

    PubMed

    Manfré, Giuseppe; Doyère, Valérie; Bossi, Simon; Riess, Olaf; Nguyen, Huu Phuc; El Massioui, Nicole

    2016-02-15

    Impulsivity trait was characterized in 3-5 months old BACHD rats, a transgenic model of Huntington disease, using (1) the delay discounting task to assess cognitive/choice impulsivity, and (2) the Differential Reinforcement of Low Rate of Responding task to evaluate motor/action impulsivity. Transgenic animals showed a high level of choice impulsivity and, to a lesser extent, action impulsivity. Our results provide the first evidence that the transgenic BACHD rat (TG5 line) displays impulsivity disorder as early as 3 months old, as described in early symptomatic HD patients, thus adding to the face validity of the rat model.

  10. Short range micro-power impulse radar with high resolution swept range gate with damped transmit and receive cavities

    DOEpatents

    McEwan, T.E.

    1998-06-30

    A radar range finder and hidden object locator is based on ultra-wide band radar with a high resolution swept range gate. The device generates an equivalent time amplitude scan with atypical range of 4 inches to 20 feet, and an analog range resolution as limited by a jitter of on the order of 0.01 inches. A differential sampling receiver is employed to effectively eliminate ringing and other aberrations induced in the receiver by the near proximity of the transmit antenna, so a background subtraction is not needed, simplifying the circuitry while improving performance. Uses of the invention include a replacement of ultrasound devices for fluid level sensing, automotive radar, such as cruise control and parking assistance, hidden object location, such as stud and rebar finding. Also, this technology can be used when positioned over a highway lane to collect vehicle count and speed data for traffic control. Techniques are used to reduce clutter in the receive signal, such as decoupling the receive and transmit cavities by placing a space between them, using conductive or radiative damping elements on the cavities, and using terminating plates on the sides of the openings. 20 figs.

  11. High power impulse magnetron sputtering: Current-voltage-timecharacteristics indicate the onset of sustained self-sputtering

    SciTech Connect

    Anders, Andre; Andersson, Joakim; Ehiasarian, Arutiun

    2007-08-03

    The commonly used current-voltage characteristics are foundinadequate for describing the pulsed nature of the high power impulsemagnetron sputtering (HIPIMS) discharge, rather, the description needs tobe expanded to current-voltage-time characteristics for each initial gaspressure. Using different target materials (Cu, Ti, Nb, C, W, Al, Cr) anda pulsed constant-voltage supply it is shown that the HIPIMS dischargestypically exhibit an initial pressure dependent current peak followed bya second phase that is power and material dependent. This suggests thatthe initial phase of a HIPIMS discharge pulse is dominated by gas ionswhereas the later phase has a strong contribution from self-sputtering.For some materials the discharge switches into a mode of sustainedself-sputtering. The very large differences between materials cannot beascribed to the different sputter yields but they indicate thatgeneration and trapping ofsecondary electrons plays a major role forcurrent-voltage-time characteristics. In particular, it is argued thatthe sustained self-sputtering phase is associated with thegeneration ofmultiply charged ions because only they can cause potential emission ofsecondary electrons whereas the yield caused by singly charged metal ionsis negligibly small.

  12. Short range micro-power impulse radar with high resolution swept range gate with damped transmit and receive cavities

    DOEpatents

    McEwan, Thomas E.

    1998-01-01

    A radar range finder and hidden object locator is based on ultra-wide band radar with a high resolution swept range gate. The device generates an equivalent time amplitude scan with atypical range of 4 inches to 20 feet, and an analog range resolution as limited by a jitter of on the order of 0.01 inches. A differential sampling receiver is employed to effectively eliminate ringing and other aberrations induced in the receiver by the near proximity of the transmit antenna, so a background subtraction is not needed, simplifying the circuitry while improving performance. Uses of the invention include a replacement of ultrasound devices for fluid level sensing, automotive radar, such as cruise control and parking assistance, hidden object location, such as stud and rebar finding. Also, this technology can be used when positioned over a highway lane to collect vehicle count and speed data for traffic control. Techniques are used to reduce clutter in the receive signal, such as decoupling the receive and transmit cavities by placing a space between them, using conductive or radiative damping elements on the cavities, and using terminating plates on the sides of the openings.

  13. Physical and electrical properties of induced high-k ZrHfO crystallization with ZrN cap by high power impulse magnetron sputtering for metal-gate metal-insulator-semiconductor structures

    NASA Astrophysics Data System (ADS)

    Tsai, Jung-Ruey; Juan, Pi-Chun; Lin, Cheng-Li; Lin, Guo-Cheng

    2017-01-01

    Metal-gate TiN/ZrN/ZrHfO/p-Si metal-insulator-semiconductor (MIS) structures have been fabricated in this work. The physical and electrical properties were characterized. The crystallization of high-k ZrHfO thin-film is induced by high power impulse magnetron sputtering (HIPIMS) during the deposition of ZrN capping layer. The binding energies and depth profiles were investigated by X-ray photoelectron spectroscopy (XPS). It is found that Zr and Hf out-diffusion from high-k dielectric in samples with HIPIMS is lesser than those in samples with the conventional DC magnetron sputtering (DCMS). The dielectric constant which strongly relates to the tetragonal phase becomes higher and the flatband voltage shift shows smaller by using the HIPIMS method than by the conventional DCMS. The cation and anion vacancies have been investigated by the defect reaction model.

  14. Influence of feeders on operating characteristics of the impulse seals

    NASA Astrophysics Data System (ADS)

    Martsynkovskyy, V. A.; Hudkov, S.; Kundera, C.

    2017-08-01

    The paper presents an refined calculation of impulse face seals with a self-regulated gap. Unlike the existing methods of calculation, wherein, for the sake of simplicity, influence of the feeder conductance is neglected, this article describes conductance effect on the operating characteristics of the seal. Static calculation method of a face impulse seal of the high-speed pump is presented.

  15. The Antarctic Impulsive Transient Antenna ultra-high energy neutrino detector: Design, performance, and sensitivity for 2006-2007 balloon flight

    SciTech Connect

    Gorham, P. W.; Allison, P.; Barwick, S. W.; Beatty, J. J.; Besson, D. Z.; Binns, W. R.; Chen, C.; Chen, P.; Clem, J. M.; Connolly, A.; Dowkontt, P. F.; DuVernois, M. A.; Field, R. C.; Goldstein, D.; Goodhue, A.; Hast, C.; Hebert, C. L.; Hoover, S.; Israel, M. H.; Learned, J. G.

    2009-05-23

    In this article, we present a comprehensive report on the experimental details of the Antarctic Impulsive Transient Antenna (ANITA) long-duration balloon payload, including the design philosophy and realization, physics simulations, performance of the instrument during its first Antarctic flight completed in January of 2007, and expectations for the limiting neutrino detection sensitivity.

  16. High-intensity drying processes -- Impulse drying: Report 15 (final report). Production of linerboard on a pilot paper machine, subsequent commercial converting trials and preliminary economic assessment

    SciTech Connect

    Orloff, D.I.

    1999-04-01

    In September 1998, 33{number_sign} liner was produced on the {number_sign}4 pilot machine under both single-felted wet pressing and impulse drying conditions. In October 1998, the pilot produced liner and commercial liner were converted to combined board and corrugated boxes at a commercial box plant. In January 1999, linerboard, medium, and combined board and box testing were completed. The pilot trials demonstrated that 33{number_sign} liner could be impulse dried at a reel speed of 380 m/min. Press dryness was improved by as much as 4 points, while CD STFI and CD ring crush were improved by more than 10%. Improvements to the smoothness of heated side of sheet were also realized. Commercial box plant converting trials demonstrated that impulse dried linerboard can be used to increase ECT and box compression strength by as much as 10%. As anticipated, print quality was found to be superior. A preliminary economic analysis was performed in which an impulse dryer would increase press dryness by 4 points and would allow the basis weight to be reduced by 10%. The economic model showed that the 4 points in dryness would translate to a 17% tonnage increase. Applying the 10% basis weight reduction resulted in an increase in productivity, on an area basis, of 30%. The pulp cost savings was found to outweigh any additional electric power costs.

  17. Impulsive Aggression as a Comorbidity of Attention-Deficit/Hyperactivity Disorder in Children and Adolescents

    PubMed Central

    Amann, Birgit H.

    2016-01-01

    Abstract Objective: This article examines the characteristics of impulsive aggression (IA) as a comorbidity in children and adolescents with attention-deficit/hyperactivity disorder (ADHD), focusing on its incidence, impact on ADHD outcomes, need for timely intervention, and limitations of current treatment practices. Methods: Relevant literature was retrieved with electronic searches in PubMed and PsycINFO using the search strategy of “ADHD OR attention deficit hyperactivity disorder” AND “impulsive aggression OR reactive aggression OR hostile aggression OR overt aggression” AND “pediatric OR childhood OR children OR pre-adolescent OR adolescent” with separate searches using review OR clinical trial as search limits. Key articles published before the 2007 Expert Consensus Report on IA were identified using citation analysis. Results: More than 50% of preadolescents with ADHD combined subtype reportedly display clinically significant aggression, with impulsive aggression being the predominant subtype. Impulsive aggression is strongly predictive of a highly unfavorable developmental trajectory characterized by the potential for persistent ADHD, increasing psychosocial burden, accumulating comorbidities, serious lifelong functional deficits across a broad range of domains, delinquency/criminality, and adult antisocial behavior. Impulsive aggression, which triggers peer rejection and a vicious cycle of escalating dysfunction, may be a key factor in unfavorable psychosocial outcomes attributed to ADHD. Because severe aggressive behavior does not remit in many children when treated with primary ADHD therapy (i.e., stimulants and behavioral therapy), a common practice is to add medication of a different class to specifically target aggressive behavior. Conclusions: Impulsive aggression in children and adolescents with ADHD is a serious clinical and public health problem. Although adjunctive therapy with an aggression-targeted agent is widely recommended when

  18. Oscillatory Activity in the Medial Prefrontal Cortex and Nucleus Accumbens Correlates with Impulsivity and Reward Outcome

    PubMed Central

    Rich, P. Dylan; Nevado-Holgado, Alejo J.; Fernando, Anushka B. P.; Van Dijck, Gert; Holzhammer, Tobias; Paul, Oliver; Ruther, Patrick; Paulsen, Ole; Robbins, Trevor W.; Dalley, Jeffrey W.

    2014-01-01

    Actions expressed prematurely without regard for their consequences are considered impulsive. Such behaviour is governed by a network of brain regions including the prefrontal cortex (PFC) and nucleus accumbens (NAcb) and is prevalent in disorders including attention deficit hyperactivity disorder (ADHD) and drug addiction. However, little is known of the relationship between neural activity in these regions and specific forms of impulsive behaviour. In the present study we investigated local field potential (LFP) oscillations in distinct sub-regions of the PFC and NAcb on a 5-choice serial reaction time task (5-CSRTT), which measures sustained, spatially-divided visual attention and action restraint. The main findings show that power in gamma frequency (50–60 Hz) LFP oscillations transiently increases in the PFC and NAcb during both the anticipation of a cue signalling the spatial location of a nose-poke response and again following correct responses. Gamma oscillations were coupled to low-frequency delta oscillations in both regions; this coupling strengthened specifically when an error response was made. Theta (7–9 Hz) LFP power in the PFC and NAcb increased during the waiting period and was also related to response outcome. Additionally, both gamma and theta power were significantly affected by upcoming premature responses as rats waited for the visual cue to respond. In a subgroup of rats showing persistently high levels of impulsivity we found that impulsivity was associated with increased error signals following a nose-poke response, as well as reduced signals of previous trial outcome during the waiting period. Collectively, these in-vivo neurophysiological findings further implicate the PFC and NAcb in anticipatory impulsive responses and provide evidence that abnormalities in the encoding of rewarding outcomes may underlie trait-like impulsive behaviour. PMID:25333512

  19. Impulsive Aggression as a Comorbidity of Attention-Deficit/Hyperactivity Disorder in Children and Adolescents.

    PubMed

    Saylor, Keith E; Amann, Birgit H

    2016-02-01

    This article examines the characteristics of impulsive aggression (IA) as a comorbidity in children and adolescents with attention-deficit/hyperactivity disorder (ADHD), focusing on its incidence, impact on ADHD outcomes, need for timely intervention, and limitations of current treatment practices. Relevant literature was retrieved with electronic searches in PubMed and PsycINFO using the search strategy of "ADHD OR attention deficit hyperactivity disorder" AND "impulsive aggression OR reactive aggression OR hostile aggression OR overt aggression" AND "pediatric OR childhood OR children OR pre-adolescent OR adolescent" with separate searches using review OR clinical trial as search limits. Key articles published before the 2007 Expert Consensus Report on IA were identified using citation analysis. More than 50% of preadolescents with ADHD combined subtype reportedly display clinically significant aggression, with impulsive aggression being the predominant subtype. Impulsive aggression is strongly predictive of a highly unfavorable developmental trajectory characterized by the potential for persistent ADHD, increasing psychosocial burden, accumulating comorbidities, serious lifelong functional deficits across a broad range of domains, delinquency/criminality, and adult antisocial behavior. Impulsive aggression, which triggers peer rejection and a vicious cycle of escalating dysfunction, may be a key factor in unfavorable psychosocial outcomes attributed to ADHD. Because severe aggressive behavior does not remit in many children when treated with primary ADHD therapy (i.e., stimulants and behavioral therapy), a common practice is to add medication of a different class to specifically target aggressive behavior. Impulsive aggression in children and adolescents with ADHD is a serious clinical and public health problem. Although adjunctive therapy with an aggression-targeted agent is widely recommended when aggressive behaviors do not remit with primary ADHD therapy

  20. External eating mediates the relationship between impulsivity and unhealthy food intake.

    PubMed

    Kakoschke, Naomi; Kemps, Eva; Tiggemann, Marika

    2015-08-01

    Recent evidence from the eating domain shows a link between impulsivity and unhealthy food intake. However, the mechanism underlying this relationship remains unclear. One possibility is an external eating style, which has been linked to both impulsivity and food intake. The current study investigated the potential mediating role of external eating in the relationship between impulsivity and food intake. Participants were 146 undergraduate women who completed measures of impulsivity and external eating, and took part in a laboratory taste test as a behavioural index of unhealthy snack food intake. It was found that attentional and motor impulsivity interacted in predicting sweet food intake, but only motor impulsivity predicted both external eating and sweet food intake. Furthermore, the relationship between motor impulsivity and food intake was mediated by external eating. These findings support the development of interventions aimed at targeting specific aspects of impulsivity in order to reduce unhealthy eating behaviour. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. [Impulsivity and decision making in alcohol-addicted individuals].

    PubMed

    Kałwa, Agnieszka

    2013-01-01

    Decision making processes are the research problem, that has been increasingly undertaken. Alcohol addiction is a disease associated with unfavorable decision making, in spite of its negative consequences. Impulsivity plays an important role in alcoholics' decision making. It can be understood in terms of behavioral and/or cognitive flexibility disorders, that manifest in cognitive function disorders, making it difficult or even impossible to quickly and adequately assess the situation and to adjust behavior according to its requirements.. Neurobiological and genetic research indicate the existing relationship between impulsivity and certain genetic predisposition. In alcohol addicts, impulsivity can be understood also in terms of specific personality traits, e.g. novelty seeking according to the theory of Cloninger. Although the concept of impulsivity itself has been the main topic of many studies, not many of them concern also decision making processes. In studies concerning alcoholics' decision making, the relationship between this processes and behavioral impulsivity defined in many different ways, has been noticed. Some of these works define unfavorable decision making processes itself as a feature of impulsivity. Based on the results of theoretical works and research studies, it seems that it would be worth to define more precisely the concept of impulsivity, in order to determine its effect on decision making. The assessment of whether - and to what extent - the two variables (impulsivity and decision making) can be considered as separate should also be taken into account.

  2. Indirect effects of trait impulsivity on body mass.

    PubMed

    Meule, Adrian; Blechert, Jens

    2017-08-01

    Trait impulsivity has been suggested as a risk factor for weight gain. However, it is implausible that a construct that does not cover energy intake or expenditure affects fat mass directly. Instead, it is likely that eating-related variables mediate the effect of impulsivity on body mass. In the current study, a serial mediation model tested two eating-related variables (trait food craving and perceived self-regulatory success in weight regulation) as mediators of the relationship between trait impulsivity and body mass. Participants (n=432, 88% female, 79% students) completed the Barratt Impulsiveness Scale - short form, the Food Cravings Questionnaire-Trait-reduced, and the Perceived Self-Regulatory Success in Dieting Scale (PSRS), in addition to providing sociodemographic and anthropometric data. Trait impulsivity did not correlate with body mass index (BMI), but was indirectly related to BMI via food cravings and PSRS scores. Specifically, higher impulsivity predicted more frequent food cravings, which in turn predicted lower perceived self-regulatory success in eating and weight regulation, which in turn predicted higher BMI. Findings suggest possible mechanisms that mediate the association between impulsivity and BMI. Importantly, they show that impulsivity can indirectly affect BMI via eating-related variables, even in the absence of a total effect. Longitudinal studies are needed that support these assumed causal directions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Impulse pumping modelling and simulation

    NASA Astrophysics Data System (ADS)

    Pierre, B.; Gudmundsson, J. S.

    2010-08-01

    Impulse pumping is a new pumping method based on propagation of pressure waves. Of particular interest is the application of impulse pumping to artificial lift situations, where fluid is transported from wellbore to wellhead using pressure waves generated at wellhead. The motor driven element of an impulse pumping apparatus is therefore located at wellhead and can be separated from the flowline. Thus operation and maintenance of an impulse pump are facilitated. The paper describes the different elements of an impulse pumping apparatus, reviews the physical principles and details the modelling of the novel pumping method. Results from numerical simulations of propagation of pressure waves in water-filled pipelines are then presented for illustrating impulse pumping physical principles, and validating the described modelling with experimental data.

  4. New Mexico High School Competency Examination. Domain Specifications.

    ERIC Educational Resources Information Center

    New Mexico State Dept. of Education, Santa Fe. Assessment and Evaluation Unit.

    The State Department of Education is releasing the domain specifications of the New Mexico High School Competency Examination (NMHSCE) for educator use because the Spring 1996 administration of the test will be in a different form. The NMHSCE is a high school graduation requirement in New Mexico. It assesses students' competence in writing,…

  5. Preparation of Labeled Aflatoxins with High Specific Activities

    PubMed Central

    Hsieh, D. P. H.; Mateles, R. I.

    1971-01-01

    Resting cells of Aspergillus parasiticus ATCC 15517 were used to prepare highly labeled aflatoxins from labeled acetate. High synthetic activity in growing cells was evidenced only during 40 to 70 hr of incubation. Glucose was required for high incorporation efficiency, whereas the concentration of the labeled acetate determined the specific activity of the product. When labeled acetate was continuously added to maintain a concentration near but not exceeding 10 mm, in a culture containing 30 g of glucose per liter, 2% of its labels could be recovered in the purified aflatoxins which have a specific activity more than three times that of the labeled acetate. PMID:4329435

  6. Impulse control disorders and attention deficit disorder in pathological gamblers.

    PubMed

    Specker, S M; Carlson, G A; Christenson, G A; Marcotte, M

    1995-12-01

    Little systematic research has been done on psychiatric comorbidity of pathological gambling, an impulse control disorder. This report describes the occurrence of attention deficit disorder and impulse control disorders in 40 pathological gamblers in treatment for gambling problems and 64 controls. Diagnoses were made by structured interviews which utilized operationalized diagnostic criteria. An impulse control disorder other than pathological gambling was noted in 35% of the pathological gamblers, compared to 3% of the controls (p < .001). Compulsive buying (p < .001) and compulsive sexual behavior (p < .05) were significantly higher in pathological gamblers than controls. A strong association was seen among pathological gambling, attention deficit, and other impulse control disorders. Attention deficit disorder was seen in 20% of the pathological gamblers. Rates of impulse control disorders did not differ by gender. Implications of these high rates of comorbidity are discussed.

  7. An Exploration of Apathy and Impulsivity in Parkinson Disease

    PubMed Central

    Ahearn, David J.; McDonald, Kathryn; Barraclough, Michelle; Leroi, Iracema

    2012-01-01

    Background. Apathy and impulsivity in Parkinson disease (PD) are associated with clinically significant behavioral disorders. Aim. To explore the phenomenology, distribution, and clinical correlates of these two behaviors. Methods. In PD participants (n = 99) without dementia we explored the distribution of measures of motivation and impulsivity using univariate methods. We then undertook factor analysis to define specific underlying dimensions of apathy and impulsivity. Regression models were developed to determine the associated demographic and clinical features of the derived dimensions. Results. The factor analysis of apathy (AES-C) revealed a two-factor solution: “cognitive-behavior” and “social indifference”. The factor analysis of impulsivity (BIS-11) revealed a five-factor solution: “inattention”; “impetuosity”; “personal security”; “planning”; and “future orientation”. Apathy was significantly associated with: age, age of motor symptom onset (positive correlation), disease stage, motor symptom severity, and depression. Impulsivity was significantly associated with: age of motor symptom onset (negative correlation), gambling and anxiety scores, and motor complications. We observed an overlap of apathy and impulsivity in some participants. Conclusion. In PD, apathy and impulsivity have specific phenomenological profiles and are associated with particular clinical phenotypes. In spite of this, there is some overlap of behaviors which may suggests common aspects in the pathology underlying motivation and reward processes. PMID:22829814

  8. Angular Impulse and Balance Regulation During the Golf Swing.

    PubMed

    Peterson, Travis J; Wilcox, Rand R; McNitt-Gray, Jill L

    2016-08-01

    Our aim was to determine how skilled players regulate linear and angular impulse while maintaining balance during the golf swing. Eleven highly-skilled golf players performed swings with a 6-iron and driver. Components contributing to linear and angular impulse generated by the rear and target legs (resultant horizontal reaction force [RFh], RFh-angle, and moment arm) were quantified and compared across the group and within a player (α = .05). Net angular impulse generated by both the rear and target legs was greater for the driver than the 6-iron. Mechanisms used to regulate angular impulse generation between clubs varied across players and required coordination between the legs. Increases in net angular impulse with a driver involved increases in target leg RFh. Rear leg RFh-angle was maintained between clubs whereas target leg RFh became more aligned with the target line. Net linear impulse perpendicular to the target line remained near zero, preserving balance, while net linear impulse along the target line decreased in magnitude. These results indicate that the net angular impulse was regulated between clubs by coordinating force generation of the rear and target legs while sustaining balance throughout the task.

  9. Advanced Tribological Coatings for High Specific Strength Alloys

    DTIC Science & Technology

    1989-09-29

    Hard Anodised 4 HSSA12 (SHT) Plasma Nitrided 1 HSSA13 (H&G) Plasma Nitrided 2 HSSA14 (SHT) High Temperature Nitrocarburized 1 HSSA15 (H&G) Nitrox 1...HSSA26 ( High Temperature Plasma Nitriding) has recently arrived, and is currently undergoing metallographic examination. The remaining samples are still...Report No 3789/607 Advanced Tribological Coatings For High Specific Strength Alloys, R&D 5876-MS-01 Contract DAJ A45-87-C-0044 5th Interim Report

  10. Impulsivity and self-harm in adolescence: a systematic review.

    PubMed

    Lockwood, Joanna; Daley, David; Townsend, Ellen; Sayal, Kapil

    2017-04-01

    Research supports an association between impulsivity and self-harm, yet inconsistencies in methodology across studies have complicated understanding of this relationship. This systematic review examines the association between impulsivity and self-harm in community-based adolescents aged 11-25 years and aims to integrate findings according to differing concepts and methods. Electronic searches of EMBASE, MEDLINE, PsychINFO, CINAHL, PubMed and The Cochrane Library, and manual searches of reference lists of relevant reviews identified 4496 articles published up to July 2015, of which 28 met inclusion criteria. Twenty-four of the studies reported an association between broadly specified impulsivity and self-harm. However, findings varied according to the conception and measurement of impulsivity and the precision with which self-harm behaviours were specified. Specifically, lifetime non-suicidal self-injury was most consistently associated with mood-based impulsivity-related traits. However, cognitive facets of impulsivity (relating to difficulties maintaining focus or acting without forethought) differentiated current self-harm from past self-harm. These facets also distinguished those with thoughts of self-harm (ideation) from those who acted on thoughts (enaction). The findings suggested that mood-based impulsivity is related to the initiation of self-harm, while cognitive facets of impulsivity are associated with the maintenance of self-harm. In addition, behavioural impulsivity is most relevant to self-harm under conditions of negative affect. Collectively, the findings indicate that distinct impulsivity facets confer unique risks across the life-course of self-harm. From a clinical perspective, the review suggests that interventions focusing on reducing rash reactivity to emotions or improving self-regulation and decision making may offer most benefit in supporting those who self-harm.

  11. Specific Impulses Losses in Solid Propellant Rockets

    DTIC Science & Technology

    1974-12-17

    The scanning electron microscope permits better image definition and -19-j offers numerous magnification possibilities. The plates are vacuum...encounter- ing one another agglomerate instantaneously and definitively . The condensed phase is described locally by the distribution law according to the...with the gaseous phase are translated by force terms and definition of the mean magnitude by supplementary terms. We can define a derivative in

  12. Volume-surface barrier discharge in dried air in three-electrode system fed by impulse high voltage with nanosecond rise time

    NASA Astrophysics Data System (ADS)

    Malashin, Maxim; Rebrov, Igor; Nebogatkin, Sergey; Sokolova, Marina; Nikitin, Alexey; Voevodin, Vadim; Krivov, Sergey

    2016-08-01

    Results of experimental investigation of a volume-surface barrier discharge in a three-electrode system under periodic impulse voltage applied to the surface discharge (SD) electrodes and a d.c. potential applied to an additional third electrode are presented. It is shown that there is a strong influence of polarity and amplitude of the d.c. potential on the direct current "extracted" out of the surface discharge plasma layer by electric field of the third electrode. The amount of charged positive species that constitute the "extracted" current prevails under positive impulse voltage for low values of the negative d.c. potential of the third electrode. The amount of negative species prevails with higher values of the positive d.c. positive of the third electrode. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  13. Neurobiological correlates of impulsivity in healthy adults: Lower prefrontal gray matter volume and spontaneous eye-blink rate but greater resting-state functional connectivity in basal ganglia-thalamo-cortical circuitry.

    PubMed

    Korponay, Cole; Dentico, Daniela; Kral, Tammi; Ly, Martina; Kruis, Ayla; Goldman, Robin; Lutz, Antoine; Davidson, Richard J

    2017-08-15

    Studies consistently implicate aberrance of the brain's reward-processing and decision-making networks in disorders featuring high levels of impulsivity, such as attention-deficit hyperactivity disorder, substance use disorder, and psychopathy. However, less is known about the neurobiological determinants of individual differences in impulsivity in the general population. In this study of 105 healthy adults, we examined relationships between impulsivity and three neurobiological metrics - gray matter volume, resting-state functional connectivity, and spontaneous eye-blink rate, a physiological indicator of central dopaminergic activity. Impulsivity was measured both by performance on a task of behavioral inhibition (go/no-go task) and by self-ratings of attentional, motor, and non-planning impulsivity using the Barratt Impulsiveness Scale (BIS-11). Overall, we found that less gray matter in medial orbitofrontal cortex and paracingulate gyrus, greater resting-state functional connectivity between nodes of the basal ganglia-thalamo-cortical network, and lower spontaneous eye-blink rate were associated with greater impulsivity. Specifically, less prefrontal gray matter was associated with higher BIS-11 motor and non-planning impulsivity scores, but was not related to task performance; greater correlated resting-state functional connectivity between the basal ganglia and thalamus, motor cortices, and prefrontal cortex was associated with worse no-go trial accuracy on the task and with higher BIS-11 motor impulsivity scores; lower spontaneous eye-blink rate was associated with worse no-go trial accuracy and with higher BIS-11 motor impulsivity scores. These data provide evidence that individual differences in impulsivity in the general population are related to variability in multiple neurobiological metrics in the brain's reward-processing and decision-making networks. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Impulsivity-related brain volume deficits in schizophrenia-addiction comorbidity.

    PubMed

    Schiffer, Boris; Müller, Bernhard W; Scherbaum, Norbert; Forsting, Michael; Wiltfang, Jens; Leygraf, Norbert; Gizewski, Elke R

    2010-10-01

    Despite a high prevalence of schizophrenia patients with comorbid substance abuse, little is known about possible impacts on the brain. Hence, our goal was to determine whether addicted and non-addicted schizophrenic patients suffer from different brain deficits. We were especially interested to determine if grey matter volumes were affected by impulsivity. We hypothesized that (comorbid) substance abuse would be associated with enhanced impulsivity and that this enhanced impulsivity would be related to grey matter volume deficits in prefrontal areas. We employed a voxel-based morphometry approach as well as neuropsychological assessment of executive functions and trait impulsivity in 51 participants (age range 23-55). The schizophrenia group comprised 24 patients (12 patients with paranoid schizophrenia and 12 with additional comorbid substance use disorders). The comparison group comprised 27 non-schizophrenic individuals, matched by age and education (14 healthy individuals and 13 patients with substance use disorders). Total grey matter volume deficits were found in all patient groups as compared with healthy controls but were largest (~8%) in both addicted groups. While grey matter volume losses in lateral orbitofrontal and temporal regions were affected by schizophrenia, volume decreases of the medial orbitofrontal, anterior cingulate and frontopolar cortex were associated with addiction. Compared with non-addicted schizophrenics, comorbid patients showed significant volume decreases in anterior cingulate, frontopolar and superior parietal regions. Additionally, they showed an increased non-planning impulsivity that was negatively related to grey matter volumes in the same regions, except for parietal ones. The present study indicates severe grey matter volume and functional executive deficits in schizophrenia, which were only partially exacerbated by comorbid addiction. However, the relationship between non-planning impulsivity and anterior cingulate and

  15. The high prevalence of impulse control behaviors in patients with early-onset Parkinson's disease: A cross-sectional multicenter study.

    PubMed

    Vela, L; Martínez Castrillo, J C; García Ruiz, P; Gasca-Salas, C; Macías Macías, Y; Pérez Fernández, E; Ybot, I; Lopez Valdés, E; Kurtis, M M; Posada Rodriguez, I J; Mata, M; Ruiz Huete, C; Eimil, M; Borrue, C; Del Val, J; López-Manzanares, L; Rojo Sebastian, A; Marasescu, R

    2016-09-15

    In Parkinson's disease patients, impulse control disorders (ICDs) have been associated with younger age and early disease onset, yet the prevalence of ICDs in early-onset Parkinson's disease (EOPD) patients has yet to be studied. Thus, we set out to compare the prevalence of impulse control behaviors (ICBs) in a cohort of EOPD patients with that in age and gender matched healthy controls (HCs), as well as to analyze the association of these symptoms with the use of dopaminergic drugs and other clinical or demographic factors. A cross-sectional, multicenter study was carried out on patients recruited from outpatient Movement Disorder Clinics, assessing ICBs using the short form of the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease (QUIP). In addition, depression and quality of life (QoL) were measured, along with other demographic and clinical variables. Of the 87 EOPD patients, 49 (58.3%) displayed an ICB, as did 28 of the 87 HCs (32.9%; p=0.001). Most of the EOPD patients that displayed an ICB (91.8%) were medicated with a dopamine agonist (DA) and accordingly, DA treatment was associated with a 7-fold increased risk of developing an ICB. Patients with ICBs had a higher depression score and a worse QoL. ICBs are much more prevalent in EOPD patients than in HCs and they are associated with DA intake, depression and a worse QoL. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Response inhibition in the parametric go/no-go task and its relation to impulsivity and subclinical psychopathy.

    PubMed

    Weidacker, Kathrin; Whiteford, Seb; Boy, Frederic; Johnston, Stephen J

    2017-03-01

    The current study utilizes the parametric go/no-go task (PGNG), a task that examines changes in inhibitory performance as executive function load increases, to examine the link between psychopathic traits, impulsivity, and response inhibition in a cohort of healthy participants. The results show that as executive function load increased, inhibitory ability decreased. High scores on the Cognitive Complexity subscale of the Barratt Impulsivity Scale (BIS-11) predict poor inhibitory ability in the PGNG. Similarly, high scores on the Psychopathy Personality Inventory-Revised (PPI-R) Blame Externalization subscale predict response inhibition deficits in the PGNG, which loads more on the executive functions than the standard go/no-go task. The remaining BIS-11 as well as PPI-R subscales did not interact with inhibitory performance in the PGNG highlighting the specificity of associations between aspects of personality and impulsivity with inhibitory performance as cognitive load is increased. These data point towards the sensitivity of the PGNG in studying response inhibition in the context of highly impulsive populations and its utility as a measure of impulsivity.

  17. Impulsivity in Decision-Making: An Event-Related Potential Investigation

    PubMed Central

    Martin, Laura E.; Potts, Geoffrey F.

    2009-01-01

    Impulsive individuals make risky choices, motivated more by immediate reward than potential long-term negative consequences. We used event-related potentials to study the impact of reward and punishment sensitivity in impulsivity on risky decision-making in a two-card choice task in groups of 14 high and 14 low impulsive undergraduates formed by a median split on the Barratt Impulsiveness Scale score. The high impulsives had a larger P3 and the low impulsives a smaller P3 to the cards when making a low-risk choice suggesting that the high-risk option was the default choice of the high impulsives and the low-risk choice the default for the low impulsives. The low, but not the high impulsives had a larger error-related negativity following high-risk choice indicating that the low impulsives evaluated the risky choice as a poor decision. The results indicate that high impulsive individuals are biased towards immediate reward during option evaluation but are less sensitive to the negative consequences of their choices. PMID:20126284

  18. Heroin and amphetamine users display opposite relationships between trait and neurobehavioral dimensions of impulsivity

    PubMed Central

    Vassileva, Jasmin; Paxton, Jessica; Moeller, F. Gerard; Wilson, Michael; Bozgunov, Kiril; Martin, Eileen; Gonzalez, Raul; Vasilev, Georgi

    2014-01-01

    The multidimensional construct of impulsivity is implicated in all phases of the addiction cycle. Substance dependent individuals (SDIs) demonstrate elevated impulsivity on both trait and laboratory tests of neurobehavioral impulsivity; however our understanding of the relationship between these different aspects of impulsivity in users of different classes of drugs remains rudimentary. The goal of this study was to assess for commonalities and differences in the relationships between trait and neurobehavioral impulsivity in heroin and amphetamine addicts. Participants included 58 amphetamine dependent (ADI) and 74 heroin dependent individuals (HDI) in protracted abstinence. We conducted principal components analyses (PCA) on two self-report trait and six neurobehavioral measures of impulsivity, which resulted in two trait impulsivity (action, planning) and four neurobehavioral impulsivity composites (discriminability, response inhibition efficiency, decision-making efficiency, quality of decision-making). Multiple regression analyses were used to determine whether neurobehavioral impulsivity is predicted by trait impulsivity and drug type. The analyses revealed a significant interaction between drug type and trait action impulsivity on response inhibition efficiency, which showed opposite relationships for ADIs and HDIs. Specifically, increased trait action impulsivity was associated with worse response inhibition efficiency in ADIs, but with better efficiency in HDIs. These results challenge the unitary account of drug addiction and contribute to a growing body of literature that reveals important behavioral, cognitive, and neurobiological differences between users of different classes of drugs. PMID:24342174

  19. Heroin and amphetamine users display opposite relationships between trait and neurobehavioral dimensions of impulsivity.

    PubMed

    Vassileva, Jasmin; Paxton, Jessica; Moeller, F Gerard; Wilson, Michael J; Bozgunov, Kiril; Martin, Eileen M; Gonzalez, Raul; Vasilev, Georgi

    2014-03-01

    The multidimensional construct of impulsivity is implicated in all phases of the addiction cycle. Substance dependent individuals (SDIs) demonstrate elevated impulsivity on both trait and laboratory tests of neurobehavioral impulsivity; however our understanding of the relationship between these different aspects of impulsivity in users of different classes of drugs remains rudimentary. The goal of this study was to assess for commonalities and differences in the relationships between trait and neurobehavioral impulsivity in heroin and amphetamine addicts. Participants included 58 amphetamine dependent (ADIs) and 74 heroin dependent individuals (HDIs) in protracted abstinence. We conducted Principal Component Analyses (PCA) on two self-report trait and six neurobehavioral measures of impulsivity, which resulted in two trait impulsivity (action, planning) and four neurobehavioral impulsivity composites (discriminability, response inhibition efficiency, decision-making efficiency, quality of decision-making). Multiple regression analyses were used to determine whether neurobehavioral impulsivity is predicted by trait impulsivity and drug type. The analyses revealed a significant interaction between drug type and trait action impulsivity on response inhibition efficiency, which showed opposite relationships for ADIs and HDIs. Specifically, increased trait action impulsivity was associated with worse response inhibition efficiency in ADIs, but with better efficiency in HDIs. These results challenge the unitary account of drug addiction and contribute to a growing body of literature that reveals important behavioral, cognitive, and neurobiological differences between users of different classes of drugs.

  20. Teaching about Impulse and Momentum

    ERIC Educational Resources Information Center

    Franklin, Bill

    2004-01-01

    This American Association of Physics Teachers/Physics Teaching Resource Agents (APPT/PTRA) spiral-bound manual features labs and demos physics teachers can use to give students hands-on opportunities to learn about impulse and momentum. "Make-and-take activities" include AAPT Apparatus Contest winners "An Air Impulse Rocket," "A Fan Driven…

  1. Teaching about Impulse and Momentum

    ERIC Educational Resources Information Center

    Franklin, Bill

    2004-01-01

    This American Association of Physics Teachers/Physics Teaching Resource Agents (APPT/PTRA) spiral-bound manual features labs and demos physics teachers can use to give students hands-on opportunities to learn about impulse and momentum. "Make-and-take activities" include AAPT Apparatus Contest winners "An Air Impulse Rocket," "A Fan Driven…

  2. Low-temperature growth of low friction wear-resistant amorphous carbon nitride thin films by mid-frequency, high power impulse, and direct current magnetron sputtering

    SciTech Connect

    Bakoglidis, Konstantinos D. Schmidt, Susann; Garbrecht, Magnus; Ivanov, Ivan G.; Jensen, Jens; Greczynski, Grzegorz; Hultman, Lars

    2015-09-15

    The potential of different magnetron sputtering techniques for the synthesis of low friction and wear resistant amorphous carbon nitride (a-CN{sub x}) thin films onto temperature-sensitive AISI52100 bearing steel, but also Si(001) substrates was studied. Hence, a substrate temperature of 150 °C was chosen for the film synthesis. The a-CN{sub x} films were deposited using mid-frequency magnetron sputtering (MFMS) with an MF bias voltage, high power impulse magnetron sputtering (HiPIMS) with a synchronized HiPIMS bias voltage, and direct current magnetron sputtering (DCMS) with a DC bias voltage. The films were deposited using a N{sub 2}/Ar flow ratio of 0.16 at the total pressure of 400 mPa. The negative bias voltage, V{sub s}, was varied from 20 to 120 V in each of the three deposition modes. The microstructure of the films was characterized by high-resolution transmission electron microscopy and selected area electron diffraction, while the film morphology was investigated by scanning electron microscopy. All films possessed an amorphous microstructure, while the film morphology changed with the bias voltage. Layers grown applying the lowest substrate bias of 20 V exhibited pronounced intercolumnar porosity, independent of the sputter technique. Voids closed and dense films are formed at V{sub s} ≥ 60 V, V{sub s} ≥ 100 V, and V{sub s} = 120 V for MFMS, DCMS, and HiPIMS, respectively. X-ray photoelectron spectroscopy revealed that the nitrogen-to-carbon ratio, N/C, of the films ranged between 0.2 and 0.24. Elastic recoil detection analysis showed that Ar content varied between 0 and 0.8 at. % and increased as a function of V{sub s} for all deposition techniques. All films exhibited compressive residual stress, σ, which depends on the growth method; HiPIMS produces the least stressed films with values ranging between −0.4 and −1.2 GPa for all V{sub s}, while CN{sub x} films deposited by MFMS showed residual stresses up to −4.2

  3. Recent Insights into the Neurobiology of Impulsivity

    PubMed Central

    Mitchell, Marci R.; Potenza, Marc N.

    2014-01-01

    Impulsivity is associated with various psychopathologies, and elevated impulsivity is typically disadvantageous. This manuscript reviews recent investigations into the neurobiology of impulsivity using human imaging techniques and animal models. Both human imaging and preclinical pharmacological manipulations have yielded important insights into the neurobiological underpinnings of impulsivity. A more thorough understanding of the complex neurobiology underlying aspects of impulsivity may provide insight into new treatment options that target elevated impulsivity and psychopathologies such as addictions. PMID:25431750

  4. High specific energy and specific power aluminum/air battery for micro air vehicles

    NASA Astrophysics Data System (ADS)

    Kindler, A.; Matthies, L.

    2014-06-01

    Micro air vehicles developed under the Army's Micro Autonomous Systems and Technology program generally need a specific energy of 300 - 550 watt-hrs/kg and 300 -550 watts/kg to operate for about 1 hour. At present, no commercial cell can fulfill this need. The best available commercial technology is the Lithium-ion battery or its derivative, the Li- Polymer cell. This chemistry generally provides around 15 minutes flying time. One alternative to the State-of-the Art is the Al/air cell, a primary battery that is actually half fuel cell. It has a high energy battery like aluminum anode, and fuel cell like air electrode that can extract oxygen out of the ambient air rather than carrying it. Both of these features tend to contribute to a high specific energy (watt-hrs/kg). High specific power (watts/kg) is supported by high concentration KOH electrolyte, a high quality commercial air electrode, and forced air convection from the vehicles rotors. The performance of this cell with these attributes is projected to be 500 watt-hrs/kg and 500 watts/kg based on simple model. It is expected to support a flying time of approximately 1 hour in any vehicle in which the usual limit is 15 minutes.

  5. [Kleptomania: an irresistible impulse].

    PubMed

    Hatzigeorgiou, K

    2011-01-01

    This review presents the historical-epidemiological and clinical aspects of Kleptomania. The diagnostic criteria, on the basis of which it is categorized in the group of Impulse Control Disorders, are defined precisely. All the aspects of its causative pathogenesis are deeply analyzed, as they are projected through its phenomenological, psychoanalytical and psycho-biological approach. Particular emphasis is given on its differential diagnosis from other psycho-pathological conditions and especially from the co-morbidities that often accompany it. The frame of treatment is established and its course and the final outcome are analyzed. Finally, it is determined what should be the objectives of future research, which will contribute decisively to the ascertainment of the exact incidence of Kleptomania in the general population, to the clarification of its causative pathogenesis and especially to the most effective treatment of this serious mental disorder.

  6. Networks underlying trait impulsivity: Evidence from voxel-based lesion-symptom mapping.

    PubMed

    McDonald, Valerie; Hauner, Katherina K; Chau, Aileen; Krueger, Frank; Grafman, Jordan

    2017-02-01

    Impulsivity is considered a multidimensional construct that encompasses a range of behaviors, including poor impulse control, premature decision-making, and the inability to delay gratification. In order to determine the extent to which impulsivity and its components share a common network, a voxel-based lesion-symptom mapping (VLSM) analysis was performed in a large sample of patients (N = 131) with focal, penetrating traumatic brain injuries (pTBI). Impulsivity was assessed using the Barratt Impulsiveness Scale (BIS-11), a standard self-report measure that allows for unique estimates of global impulsivity and its factor analysis-derived components (e.g., "motor impulsivity"). Heightened global impulsivity was associated with damage to multiple areas in bilateral prefrontal cortex (PFC), left superior, middle and inferior temporal gyrus, and left hippocampus. Moreover, a cluster was identified within the left PFC associated specifically with motor impulsivity (defined as "acting without thinking"). The results were consistent with the existing literature on bilateral prefrontal cortical involvement in behavioral impulsivity, but also provided new evidence for a more complex neuroanatomical representation of this construct, characterized by left-lateralized temporal and hippocampal involvement, as well as a left-lateralized prefrontal network specifically associated with motor impulsivity. Hum Brain Mapp 38:656-665, 2017. © 2016 Wiley Periodicals, Inc.

  7. Noncovalent functionalization of carbon nanotubes for highly specific electronic biosensors

    NASA Astrophysics Data System (ADS)

    Chen, Robert J.; Bangsaruntip, Sarunya; Drouvalakis, Katerina A.; Wong Shi Kam, Nadine; Shim, Moonsub; Li, Yiming; Kim, Woong; Utz, Paul J.; Dai, Hongjie

    2003-04-01

    Novel nanomaterials for bioassay applications represent a rapidly progressing field of nanotechnology and nanobiotechnology. Here, we present an exploration of single-walled carbon nanotubes as a platform for investigating surface-protein and protein-protein binding and developing highly specific electronic biomolecule detectors. Nonspecific binding on nanotubes, a phenomenon found with a wide range of proteins, is overcome by immobilization of polyethylene oxide chains. A general approach is then advanced to enable the selective recognition and binding of target proteins by conjugation of their specific receptors to polyethylene oxide-functionalized nanotubes. This scheme, combined with the sensitivity of nanotube electronic devices, enables highly specific electronic sensors for detecting clinically important biomolecules such as antibodies associated with human autoimmune diseases.

  8. A Ratio Test of Interrater Agreement with High Specificity

    ERIC Educational Resources Information Center

    Cousineau, Denis; Laurencelle, Louis

    2015-01-01

    Existing tests of interrater agreements have high statistical power; however, they lack specificity. If the ratings of the two raters do not show agreement but are not random, the current tests, some of which are based on Cohen's kappa, will often reject the null hypothesis, leading to the wrong conclusion that agreement is present. A new test of…

  9. Alexithymia, emotion dysregulation, impulsivity and aggression: A multiple mediation model.

    PubMed

    Velotti, Patrizia; Garofalo, Carlo; Petrocchi, Chiara; Cavallo, Francesca; Popolo, Raffaele; Dimaggio, Giancarlo

    2016-03-30

    There is a need to better understand the antecedent of aggressive behaviors in order to tailor treatments and reduce the associated damage to the others and the self. Possible mechanisms underlying aggression are poor emotional awareness and emotion dysregulation, as well as impulsivity. Here, we examined the relationships among alexithymia, emotion dysregulation, impulsivity and aggression, comparing a mixed psychiatric sample (N=257) and a community sample (N=617). The clinical sample reported greater levels of alexithymia, emotion dysregulation, trait impulsivity and aggression, than the community sample. Furthermore, in the community sample, emotion dysregulation and impulsivity mediated the relationship (i.e., accounted for the shared variance) between alexithymia and aggression. In the clinical sample, only emotion dysregulation explained the alexithymia-aggression link. In particular, specific dimensions of the emotion dysregulation (i.e., Negative Urgency) and impulsivity constructs (i.e., cognitive and motor impulsivity) played a unique role in explaining these associations. Finally, controlling for depressive symptoms reduced some of the findings involving impulsivity to nonsignificant results. Overall, our findings add to the extant literature attesting to the relevance of alexithymia and emotion dysregulation for understanding aggression, and providing concrete recommendation for the treatment and prevention of aggressive tendencies.

  10. Individual differences in impulsive action and dopamine transporter function in rat orbitofrontal cortex.

    PubMed

    Yates, J R; Darna, M; Beckmann, J S; Dwoskin, L P; Bardo, M T

    2016-01-28

    Impulsivity, which can be subdivided into impulsive action and impulsive choice, is implicated as a factor underlying drug abuse vulnerability. Although previous research has shown that dopamine (DA) systems in prefrontal cortex are involved in impulsivity and substance abuse, it is not known if inherent variation in DA transporter (DAT) function contributes to impulsivity. The current study determined if individual differences in either impulsive action or impulsive choice are related to DAT function in orbitofrontal (OFC) and/or medial prefrontal cortex (mPFC). Rats were first tested both for impulsive action in a cued go/no-go task and for impulsive choice in a delay-discounting task. Following behavioral evaluation, in vitro [(3)H]DA uptake assays were performed in OFC and mPFC isolated from individual rats. Vmax in OFC, but not mPFC, was correlated with performance in the cued go/no-go task, with decreased OFC DAT function being associated with high impulsive action. In contrast, Vmax in OFC and mPFC was not correlated with performance in the delay-discounting task. The current results demonstrate that impulsive behavior in cued go/no-go performance is associated with decreased DAT function in OFC, suggesting that hyperdopaminergic tone in this prefrontal subregion mediates, at least in part, increased impulsive action.

  11. Highly specific protein-protein interactions, evolution and negative design.

    PubMed

    Sear, Richard P

    2004-12-01

    We consider highly specific protein-protein interactions in proteomes of simple model proteins. We are inspired by the work of Zarrinpar et al (2003 Nature 426 676). They took a binding domain in a signalling pathway in yeast and replaced it with domains of the same class but from different organisms. They found that the probability of a protein binding to a protein from the proteome of a different organism is rather high, around one half. We calculate the probability of a model protein from one proteome binding to the protein of a different proteome. These proteomes are obtained by sampling the space of functional proteomes uniformly. In agreement with Zarrinpar et al we find that the probability of a protein binding a protein from another proteome is rather high, of order one tenth. Our results, together with those of Zarrinpar et al, suggest that designing, say, a peptide to block or reconstitute a single signalling pathway, without affecting any other pathways, requires knowledge of all the partners of the class of binding domains the peptide is designed to mimic. This knowledge is required to use negative design to explicitly design out interactions of the peptide with proteins other than its target. We also found that patches that are required to bind with high specificity evolve more slowly than those that are required only to not bind to any other patch. This is consistent with some analysis of sequence data for proteins engaged in highly specific interactions.

  12. Benchmarking Procedures for High-Throughput Context Specific Reconstruction Algorithms

    PubMed Central

    Pacheco, Maria P.; Pfau, Thomas; Sauter, Thomas

    2016-01-01

    Recent progress in high-throughput data acquisition has shifted the focus from data generation to processing and understanding of how to integrate collected information. Context specific reconstruction based on generic genome scale models like ReconX or HMR has the potential to become a diagnostic and treatment tool tailored to the analysis of specific individuals. The respective computational algorithms require a high level of predictive power, robustness and sensitivity. Although multiple context specific reconstruction algorithms were published in the last 10 years, only a fraction of them is suitable for model building based on human high-throughput data. Beside other reasons, this might be due to problems arising from the limitation to only one metabolic target function or arbitrary thresholding. This review describes and analyses common validation methods used for testing model building algorithms. Two major methods can be distinguished: consistency testing and comparison based testing. The first is concerned with robustness against noise, e.g., missing data due to the impossibility to distinguish between the signal and the background of non-specific binding of probes in a microarray experiment, and whether distinct sets of input expressed genes corresponding to i.e., different tissues yield distinct models. The latter covers methods comparing sets of functionalities, comparison with existing networks or additional databases. We test those methods on several available algorithms and deduce properties of these algorithms that can be compared with future developments. The set of tests performed, can therefore serve as a benchmarking procedure for future algorithms. PMID:26834640

  13. Power spectral density specifications for high-power laser systems

    SciTech Connect

    Lawson, J.K.; Aikens, D.A.; English, R.E. Jr.; Wolfe, C.R.

    1996-04-22

    This paper describes the use of Fourier techniques to characterize the transmitted and reflected wavefront of optical components. Specifically, a power spectral density, (PSD), approach is used. High power solid-state lasers exhibit non-linear amplification of specific spatial frequencies. Thus, specifications that limit the amplitude of these spatial frequencies are necessary in the design of these systems. Further, NIF optical components have square, rectangular or irregularly shaped apertures with major dimensions up-to 800 mm. Components with non-circular apertures can not be analyzed correctly with Zernicke polynomials since these functions are an orthogonal set for circular apertures only. A more complete and powerful representation of the optical wavefront can be obtained by Fourier analysis in 1 or 2 dimensions. The PSD is obtained from the amplitude of frequency components present in the Fourier spectrum. The shape of a resultant wavefront or the focal spot of a complex multicomponent laser system can be calculated and optimized using PSDs of the individual optical components which comprise the system. Surface roughness can be calculated over a range of spatial scale-lengths by integrating the PSD. Finally, since the optical transfer function (OTF) of the instruments used to measure the wavefront degrades at high spatial frequencies, the PSD of an optical component is underestimated. We can correct for this error by modifying the PSD function to restore high spatial frequency information. The strengths of PSD analysis are leading us to develop optical specifications incorporating this function for the planned National Ignition Facility (NIF).

  14. The flare kernel in the impulsive phase

    NASA Technical Reports Server (NTRS)

    Dejager, C.

    1986-01-01

    The impulsive phase of a flare is characterized by impulsive bursts of X-ray and microwave radiation, related to impulsive footpoint heating up to 50 or 60 MK, by upward gas velocities (150 to 400 km/sec) and by a gradual increase of the flare's thermal energy content. These phenomena, as well as non-thermal effects, are all related to the impulsive energy injection into the flare. The available observations are also quantitatively consistent with a model in which energy is injected into the flare by beams of energetic electrons, causing ablation of chromospheric gas, followed by convective rise of gas. Thus, a hole is burned into the chromosphere; at the end of impulsive phase of an average flare the lower part of that hole is situated about 1800 km above the photosphere. H alpha and other optical and UV line emission is radiated by a thin layer (approx. 20 km) at the bottom of the flare kernel. The upward rising and outward streaming gas cools down by conduction in about 45 s. The non-thermal effects in the initial phase are due to curtailing of the energy distribution function by escape of energetic electrons. The single flux tube model of a flare does not fit with these observations; instead we propose the spaghetti-bundle model. Microwave and gamma-ray observations suggest the occurrence of dense flare knots of approx. 800 km diameter, and of high temperature. Future observations should concentrate on locating the microwave/gamma-ray sources, and on determining the kernel's fine structure and the related multi-loop structure of the flaring area.

  15. Rapid Generation of Highly Specific Aptamers via Micromagnetic Selection

    PubMed Central

    Qian, Jiangrong; Lou, Xinhui; Zhang, Yanting; Xiao, Yi; Soh, H. Tom

    2009-01-01

    Aptamers are nucleic acid-based reagents that bind to target molecules with high affinity and specificity. However, methods for generating aptamers from random combinatorial libraries (e.g., SELEX) are often labor-intensive and time-consuming. Recent studies suggest that microfluidic SELEX (M-SELEX) technology can accelerate aptamer isolation by enabling highly stringent selection conditions through the use of very small amounts of target molecules. We present here an alternative M-SELEX method, which employs a disposable microfluidic chip to rapidly generate aptamers with high affinity and specificity. The Micro-Magnetic Separation (MMS) chip integrates microfabricated ferromagnetic structures to reproducibly generate large magnetic field gradients within its microchannel that efficiently trap magnetic bead-bound aptamers. Operation of the MMS device is facile, robust and demonstrates high recovery of the beads (99.5%), such that picomolar amounts of target molecule can be used. Importantly, the device demonstrates exceptional separation efficiency in removing weakly-bound and unbound ssDNA to rapidly enrich target-specific aptamers. As a model, we demonstrate here the generation of DNA aptamers against streptavidin in three rounds of positive selection. We further enhanced the specificity of the selected aptamers via a round of negative selection in the same device against bovine serum albumin (BSA). The resulting aptamers displayed dissociation constants ranging from 25 to 65 nM for streptavidin but negligible affinity for BSA. Since a wide spectrum of molecular targets can be readily conjugated on magnetic beads, MMS-based SELEX should provide a general platform for rapid generation of specific aptamers. PMID:19480397

  16. Impulsivity in disorders of food and drug misuse

    PubMed Central

    Mole, Tom B.; Irvine, Michael A.; Worbe, Yulia; Collins, Phoebe; Mitchell, Simon P.; Bolton, Sorcha; Harrison, Neil A.; Robbins, Trevor W.; Voon, Valerie

    2016-01-01

    Background Evidence suggests some overlap between the pathological use of food and drugs, yet how impulsivity compares across these different clinical disorders remains unclear. Substance use disorders are commonly characterized by elevated impulsivity, and impulsivity subtypes may show commonalities and differences in various conditions. We hypothesized that obese subjects with binge eating disorder (BED) and abstinent alcohol-dependent cohorts would have relatively more impulsive profiles compared to obese subjects without BED. We also predicted decision impulsivity impairment in obesity with and without BED. Methods Thirty obese subjects with BED, 30 without BED and 30 abstinent alcohol-dependent subjects and age- and gender-matched controls were tested on delay discounting (preference for a smaller immediate reward over a larger delayed reward), reflection impulsivity (rapid decision making prior to evidence accumulation) and motor response inhibition (action cancellation of a prepotent response). Results All three groups had greater delay discounting relative to healthy volunteers. Both Obese subjects without BED and alcohol dependent subjects had impaired motor response inhibition. Only Obese subjects without BED had impaired integration of available information to optimize outcomes over later trials with a cost condition. Conclusions Delay discounting appears to be a common core impairment across disorders of food and drug intake. Unexpectedly, obese subjects without BED showed greater impulsivity than obese subjects with BED. We highlight the dissociability and heterogeneity of impulsivity subtypes and add to the understanding of neurocognitive profiles across disorders involving food and drugs. Our results have therapeutic implications suggesting that disorder-specific patterns of impulsivity could be targeted. PMID:25118940

  17. "Impulsivity": relations between self-report and behavior.

    PubMed

    Sharma, Leigh; Kohl, Krista; Morgan, Theresa A; Clark, Lee Anna

    2013-03-01

    The trait of "impulsivity" is difficult to place within a personality framework due to the many potential pathways to impulsive behavior and the lack of consensus regarding the structure of the trait(s). This lack of consensus also hinders systematic investigation into relations between "impulsivity" and its behavioral manifestations. Undergraduates (Sample 1 N = 507) completed a battery of self-report measures, all purporting to assess trait "impulsivity"; a subset (n = 408) and Sample 2 (N = 388) also completed a retrospective questionnaire about specific behaviors they may have engaged in over the past year, and another subset of Sample 1 agreed to complete (n = 208) and actually completed (n = 152) a 2-week prospective measure of impulsive behaviors. Finally, a subset of Sample 1 (n = 321) and Sample 2 completed an omnibus self-report inventory in a follow-up study. Structural equation modeling confirmed a 3-factor structure of what we call impulsigenic traits-traits that are manifested in impulsive behavior. This finding is consistent with previous research and supports the growing consensus that "impulsivity" is a colloquial label attached to a group of distinct traits that have phenotypically similar behavioral manifestations. Each of these impulsigenic traits relates differentially to impulsive behavior and to broad temperamental dimensions. The results also show clear 2-factor structures of both daily and less frequent (yearly/semiyearly) impulsive behaviors. Finally, a unique method of data collection permitted an investigation of relations between the impulsigenic and other personality traits and observed behaviors, demonstrating the predictive utility of personality traits to discrete, in situ behaviors.

  18. Temperament and impulsivity predictors of smoking cessation outcomes.

    PubMed

    López-Torrecillas, Francisca; Perales, José C; Nieto-Ruiz, Ana; Verdejo-García, Antonio

    2014-01-01

    specifically novelty seeking and reward dependence, predict smoking cessation treatment retention, whereas persistence, non-planning impulsivity and poor decision-making predict smoking relapse.

  19. Heritability and Longitudinal Stability of Impulsivity in Adolescence

    PubMed Central

    Niv, Sharon; Tuvblad, Catherine; Raine, Adrian; Wang, Pan; Baker, Laura A.

    2012-01-01

    Impulsivity is a multifaceted personality construct that plays an important role throughout the lifespan in psychopathological disorders involving self-regulated behaviors. Its genetic and environmental etiology, however, is not clearly understood during the important developmental period of adolescence. This study investigated the relative influence of genes and environment on self-reported impulsive traits in adolescent twins measured on two separate occasions (waves) between the ages of 11 and 16. An adolescent version of the Barratt Impulsiveness Scale (BIS) developed for this study was factored into subscales reflecting inattention, motor impulsivity, and non-planning. Genetic analyses of these BIS subscales showed moderate heritability, ranging from 33–56% at the early wave (age 11–13 years) and 19–44% at the later wave (age 14–16 years). Moreover, genetic influences explained half or more of the variance of a single latent factor common to these subscales within each wave. Genetic effects specific to each subscale also emerged as significant, with the exception of motor impulsivity. Shared twin environment was not significant for either the latent or specific impulsivity factors at either wave. Phenotypic correlations between waves ranged from r = 0.25 to 0.42 for subscales. The stability correlation between the two latent impulsivity factors was r = 0.43, of which 76% was attributable to shared genetic effects, suggesting strong genetic continuity from mid to late adolescence. These results contribute to our understanding of the nature of impulsivity by demonstrating both multidimensionality and genetic specificity to different facets of this complex construct, as well as highlighting the importance of stable genetic influences across adolescence. PMID:22089391

  20. A Conditioned Response as a Measure of Impulsive-Compulsive Behaviours in Parkinson's Disease

    PubMed Central

    McGregor, Sarah; Kotschet, Katya; Griffiths, Robert I.; Horne, Malcolm

    2014-01-01

    Objectives Parkinson's Disease patients wore a device on the wrist that gave reminders to take levodopa and also measured bradykinesia and dyskinesia. Consumption of medications was acknowledged by placing the thumb on the device. Some patients performed this acknowledgement repeatedly and unconsciously. This study examines whether this behaviour reflected increased impulsivity. Methods and Results Twenty five participants were selected because they had i) excess acknowledgements described above or ii) Impulsive-Compulsive Behaviours or iii) neither of these. A blinded assessor applied clinical scales to measure Impulsive-Compulsive Behaviours, cognition, depression, anxiety and apathy. A Response Ratio, representing the number of acknowledgements/number of doses (expressed as a percentage) was tightly correlated with ratings of Impulsive-Compulsive Behaviours (r2 = 0.79) in 19/25 subjects. Some of these patients had dyskinesia, which was higher with extraneous responses than with response indicating medication consumption. Six of the 25 subjects had high Impulsive-Compulsive Behaviour Scores, higher apathy scores, low levels of dyskinesia and normal Response Ratios. Patients without ICB (low RR) also had low dyskinesia levels regardless of the relevance of the response. Conclusion An elevated Response Ratio is a specific measure of a type of ICB where increased incentive salience is attributed to cues by the presence of high striatal dopamine levels, manifested by high levels of dyskinesia. This study also points to a second form of ICBs which occur in the absence of dyskinesia, has normal Response Ratios and higher apathy scores, and may represent prefrontal pathology. PMID:24586685

  1. Contextualizing individual differences in error monitoring: Links with impulsivity, negative affect, and conscientiousness.

    PubMed

    Hill, Kaylin E; Samuel, Douglas B; Foti, Dan

    2016-08-01

    The error-related negativity (ERN) is a neural measure of error processing that has been implicated as a neurobehavioral trait and has transdiagnostic links with psychopathology. Few studies, however, have contextualized this traitlike component with regard to dimensions of personality that, as intermediate constructs, may aid in contextualizing links with psychopathology. Accordingly, the aim of this study was to examine the interrelationships between error monitoring and dimensions of personality within a large adult sample (N = 208). Building on previous research, we found that the ERN relates to a combination of negative affect, impulsivity, and conscientiousness. At low levels of conscientiousness, negative urgency (i.e., impulsivity in the context of negative affect) predicted an increased ERN; at high levels of conscientiousness, the effect of negative urgency was not significant. This relationship was driven specifically by the conscientiousness facets of competence, order, and deliberation. Links between personality measures and error positivity amplitude were weaker and nonsignificant. Post-error slowing was also related to conscientiousness, as well as a different facet of impulsivity: lack of perseverance. These findings suggest that, in the general population, error processing is modulated by the joint combination of negative affect, impulsivity, and conscientiousness (i.e., the profile across traits), perhaps more so than any one dimension alone. This work may inform future research concerning aberrant error processing in clinical populations.

  2. Impulsivity as a common process across borderline personality and substance use disorders.

    PubMed

    Bornovalova, Marina A; Lejuez, C W; Daughters, Stacey B; Zachary Rosenthal, M; Lynch, Thomas R

    2005-09-01

    Borderline personality disorder (BPD) is a significant public health problem characterized by persistent problems with emotional, behavioral, cognitive, and interpersonal functioning. Research indicates an especially high rate of comorbidity between BPD and Substance Use Disorders (SUD). In trying to better understand, and therefore improve the assessment, prevention, and treatment of these disorders, researchers have considered the role of impulsivity. Indeed, impulsivity consistently has been shown to be a biologically-based, heritable characteristic with emergent psychological properties linked to the development and maintenance of BPD and SUD. Following from a previous review of the comorbidity between BPD and SUD (Trull, T. J., Sher, K. J., Minks-Brown, C., Durbin, J., & Burr, R. (2000). Borderline personality disorder and substance use disorders: A review and integration. Clinical Psychology Review, 20, 235-253), the current manuscript revisits the role of impulsivity as a common process across these disorders with a specific focus on the multidimensional nature of impulsivity and its interaction with trait and state negative affectivity.

  3. Effect of management of patients with Anorexia and Bulimia nervosa on symptoms and impulsive behavior.

    PubMed

    Sernec, Karin; Tomori, Martina; Zalar, Bojan

    2010-12-01

    The aim of the study was to provide further and up to date information on the evaluation of the management of Anorexia and Bulimia nervosa at the Eating Disorders Unit (EDU) of the Ljubljana Psychiatric Clinic, based upon detailed assessment of the eating disorders specific and non specific symptoms of impulsive behaviors, highly correlated with these entities. 34 female patients with anorexia (restrictive or purgative type) and 38 female patients with Bulimia nervosa (purgative or non-purgative type) undergoing hospital treatment at the EDU were evaluated upon admission, as well as upon discharge and three and six months after discharge, using the Eating Disorder Questionnaire. Upon discharge a marked decrease in the overall symptoms was noted. The differences in symptoms incidences between the two groups were significantly specific for the individual form of eating disorder, especially upon admission, and were more pronounced in anorexia group. In later measurements, performed during the period of three and six months after discharge, a mild trend of increase in the disorder specific symptoms was detected in both groups, but was not statistically significant. In addition to binging on food, striking, quarreling and spending sprees are characteristics of patients with eating disorders, which in particular apply to the Bulimia nervosa group. Apart from the disorder specific symptoms, impulsive behavior was also reduced during study period, while the difference in its occurrence between the two groups gradually became non-significant. The management of patients with eating disorders at the EDU was successful in both groups, confirmed by an intense reduction of the disorder specific symptoms, impulsive behavior and increased stability recorded three and six months after discharge. The study strongly suggests that the effect of treatment regime for eating disorders can be predicted by careful assessment of the relevant symptoms and impulsive behavioral patterns.

  4. High specificity in plant leaf metabolic responses to arbuscular mycorrhiza.

    PubMed

    Schweiger, Rabea; Baier, Markus C; Persicke, Marcus; Müller, Caroline

    2014-05-22

    The chemical composition of plants (phytometabolome) is dynamic and modified by environmental factors. Understanding its modulation allows to improve crop quality and decode mechanisms underlying plant-pest interactions. Many studies that investigate metabolic responses to the environment focus on single model species and/or few target metabolites. However, comparative studies using environmental metabolomics are needed to evaluate commonalities of chemical responses to certain challenges. We assessed the specificity of foliar metabolic responses of five plant species to the widespread, ancient symbiosis with a generalist arbuscular mycorrhizal fungus. Here we show that plant species share a large 'core metabolome' but nevertheless the phytometabolomes are modulated highly species/taxon-specifically. Such a low conservation of responses across species highlights the importance to consider plant metabolic prerequisites and the long time of specific plant-fungus coevolution. Thus, the transferability of findings regarding phytometabolome modulation by an identical AM symbiont is severely limited even between closely related species.

  5. Impulse Generation Mechanism in Glycerin Propellant Laser Thruster

    SciTech Connect

    Fujita, Kazuhisa; Nakano, Masakatsu; Uchida, Shigeaki; Bato, Masafumi; Niino, Masayuki

    2004-03-30

    A sequential process from pulsed laser irradiation onto a spherical liquid propellant to impulse generation is discussed toward higher specific impulse performance of the thruster. A Q-switched 10-ns Nd: YAG laser pulse with 1 {mu}m wavelength was focused in a 2-mm diameter glycerin droplet in vacuum condition ({approx}10 Pa). Visible image of the droplet shot with the laser pulse, laser energy transmitted through the droplet, emission spectrum in visible to near infrared region, and temporal impulse behavior measured with piezoelectric devices were obtained. It is found that the impulse generation mechanism can be divided into energy deposition on the surface and inside of the droplet, and subsequent explosion of the droplet, depending on laser irradiation conditions.

  6. Negative emotion-driven impulsivity predicts substance dependence problems.

    PubMed

    Verdejo-García, Antonio; Bechara, Antoine; Recknor, Emily C; Pérez-García, Miguel

    2007-12-01

    Impulsivity is predominant among users of several drugs of abuse including alcohol, cocaine, and amphetamines, and it is considered a risk factor for later development of alcohol and substance abuse and dependence. However, there is little consensus on how impulsivity should be defined and measured, and there are few studies on the relationship between separate dimensions of impulsivity and substance dependence. We used a multidimensional measure of impulsivity (the UPPS scale) to examine differences between 36 individuals with substance dependence (ISD) and 36 drug-free controls on the dimensions of urgency, lack of premeditation, lack of perseverance, and sensation seeking. In addition, we examined which dimensions of impulsivity better predicted addiction-related problems as measured with the addiction severity index. Results revealed that ISD show high scores on dimensions of urgency, lack of perseverance, and lack of premeditation (effect sizes ranging from 1.10 to 1.96), but not on sensation seeking. Among the different impulsivity dimensions, urgency was the best predictor of severity of medical, employment, alcohol, drug, family/social, legal and psychiatric problems in ISD, explaining 13-48% of the total variance of these indices. Furthermore, urgency scores alone correctly classified 83% of the participants in the ISD group. Urgency is characterized by a tendency to act impulsively in response to negative emotional states. Thus, our results could have important implications for novel treatment approaches for substance dependence focused on emotional regulation.

  7. Impulsively Driven Waves And Flows In Coronal Active Regions

    NASA Astrophysics Data System (ADS)

    Ofman, Leon; Wang, T.; Davila, J. M.; Liu, W.

    2012-05-01

    Recent SDO/AIA and Hinode EIS observations indicate that both (super) fast and slow magnetosonic waves are present in active region (AR) magnetic structures. Evidence for fast (100-300 km/s) impulsive flows is found in spectroscopic and imaging observations of AR loops. The super-fast waves were observed in magnetic funnels of ARs. The observations suggest that waves and flow are produced by impulsive events, such as (micro) flares. We have performed three-dimensional magnetohydrodynamic (3D MHD) simulations of impulsively generated flows and waves in coronal loops of a model bi-polar active region (AR). The model AR is initiated with a dipole magnetic field and gravitationally stratified density, with impulsively driven flow at the coronal base of the AR in localized magnetic field structures. We model the excitation of the flows in hot (6MK) and cold (1MK) active region plasma, and find slow and fast magnetosonic waves produced by these events. We also find that high-density (compared to surrounding corona) loops are produced as a result of the upflows. We investigate the parametric dependence between the properties of the impulsive flows and the waves. The results of the 3D MHD modeling study supports the conjecture that slow magnetosonic waves are often produced by impulsive upflows along the magnetic field, and fast magnetosonic waves can result from impulsive transverse field line perturbations associated with reconnection events. The waves and flows can be used for diagnostic of AR structure and dynamics.

  8. Simulation of impulse effects from explosive charges containing metal particles

    NASA Astrophysics Data System (ADS)

    Balakrishnan, K.; Nance, D. V.; Menon, S.

    2010-06-01

    The propagation of an explosive blast wave containing inert metal particles is investigated numerically using a robust two-phase methodology with appropriate models to account for real gas behavior, inter-phase interactions, and inter-particle collisions to study the problem of interest. A new two-phase Eulerian-Lagrangian formulation is proposed that can handle the dense nature of the flow-field. The velocity and momentum profiles of the gas and particle phases are analyzed and used to elucidate the inter-phase momentum transfer, and its effect on the impulsive aspects of heterogeneous explosive charges. The particles are found to pick up significant amounts of momentum and kinetic energy from the gas, and by virtue of their inertia, are observed to sustain it for a longer time. The impulse characteristics of heterogeneous explosives are compared with a homogeneous explosive containing the same amount of high explosive, and it is observed that the addition of solid particles augments the impulsive loading significantly in the near-field, and to a smaller extent in the far-field. The total impulsive loading is found to be insensitive to the particle size added to the explosive charge above a certain cut-off radius, but the individual impulse components are found to be sensitive, and particles smaller than this cut-off size deliver about 8% higher total impulse than the larger ones. Overall, this study provides crucial insights to understand the impulsive loading characteristics of heterogeneous explosives.

  9. Accelerator Production and Separations for High Specific Activity Rhenium-186

    SciTech Connect

    Jurisson, Silvia S.; Wilbur, D. Scott

    2016-04-01

    Tungsten and osmium targets were evaluated for the production of high specific activity rhenium-186. Rhenium-186 has potential applications in radiotherapy for the treatment of a variety of diseases, including targeting with monoclonal antibodies and peptides. Methods were evaluated using tungsten metal, tungsten dioxide, tungsten disulfide and osmium disulfide. Separation of the rhenium-186 produced and recycling of the enriched tungsten-186 and osmium-189 enriched targets were developed.

  10. Method of preparing high specific activity platinum-195m

    SciTech Connect

    Mirzadeh, Saed; Du, Miting; Beets, Arnold L.; Knapp, Jr., Furn F.

    2004-06-15

    A method of preparing high-specific-activity .sup.195m Pt includes the steps of: exposing .sup.193 Ir to a flux of neutrons sufficient to convert a portion of the .sup.193 Ir to .sup.195m Pt to form an irradiated material; dissolving the irradiated material to form an intermediate solution comprising Ir and Pt; and separating the Pt from the Ir by cation exchange chromatography to produce .sup.195m Pt.

  11. Method for preparing high specific activity 177Lu

    DOEpatents

    Mirzadeh, Saed; Du, Miting; Beets, Arnold L.; Knapp, Jr., Furn F.

    2004-04-06

    A method of separating lutetium from a solution containing Lu and Yb, particularly reactor-produced .sup.177 Lu and .sup.177 Yb, includes the steps of: providing a chromatographic separation apparatus containing LN resin; loading the apparatus with a solution containing Lu and Yb; and eluting the apparatus to chromatographically separate the Lu and the Yb in order to produce high-specific-activity .sup.177 Yb.

  12. The influence of impulsiveness on binge eating and problem gambling: A prospective study of gender differences in Canadian adults.

    PubMed

    Farstad, Sarah M; von Ranson, Kristin M; Hodgins, David C; El-Guebaly, Nady; Casey, David M; Schopflocher, Don P

    2015-09-01

    This study investigated the degree to which facets of impulsiveness predicted future binge eating and problem gambling, 2 theorized forms of behavioral addiction. Participants were 596 women and 406 men from 4 age cohorts randomly recruited from a Canadian province. Participants completed self-report measures of 3 facets of impulsiveness (negative urgency, sensation seeking, lack of persistence), binge-eating frequency, and problem-gambling symptoms. Impulsiveness was assessed at baseline, and assessments of binge eating and problem gambling were followed up after 3 years. Weighted data were analyzed using zero-inflated negative binomial and Poisson regression models. We found evidence of transdiagnostic and disorder-specific predictors of binge eating and problem gambling. Negative urgency emerged as a common predictor of binge eating and problem gambling among women and men. There were disorder-specific personality traits identified among men only: High lack-of-persistence scores predicted binge eating and high sensation-seeking scores predicted problem gambling. Among women, younger age predicted binge eating and older age predicted problem gambling. Thus, there are gender differences in facets of impulsiveness that longitudinally predict binge eating and problem gambling, suggesting that treatments for these behaviors should consider gender-specific personality and demographic traits in addition to the common personality trait of negative urgency. (c) 2015 APA, all rights reserved).

  13. Elegant impulser developed for flat beam injection

    SciTech Connect

    Wilson, M. J., LLNL

    1998-05-26

    The following report describes the design, construction, and checkout of a high-voltage (HV) impulser built for the heavy ion fusion (HIF) project [1]. The purpose of this impulser is to provide an adjustable diode voltage source of sufficient quality and level to allow the optimization of beam transport and accelerator sections of HIF [2, 3]. An elegant, low-impedance, high-energy storage capacitor circuit has been selected for this application. Circuit parameters of the retrofit to the diode region [4] have been included to provide the controlled rise time. The critical part of this circuit that is common to all candidates is the impedance matching component. The following report provides a description of the implemented circuit, the basic circuit variables for wave shaping, screening techniques revealing the weakest circuit component, and the resulting output of the injector.

  14. An overview of measuring impulsive behavior in mice.

    PubMed

    Dent, Claire L; Isles, Anthony R

    2014-06-16

    Impulsive behavior is a key constituent of many psychiatric illnesses, with maladaptive response control being a feature of disorders such as ADHD, schizophrenia, mania, and addiction. In order to understand the neurological underpinnings of impulsivity, a number of behavioral tasks have been developed for use with animal models. Data from studies with rats and other animals have led to the idea of the existence of dissociable components of impulsivity, which in turn informs studies of human disorders and potentially the development of specific therapies. Increasingly, mouse models are being used to investigate the known genetic contribution to psychiatric disorders in which abnormal response control leads to altered impulsive behaviors. In order to maximize the potential of these mouse models, it is important that researchers take into account the non-unitary nature of response control and impulsivity. In this article, we briefly review the tasks available to behavioral neuroscientists and how these can be used in order to tease apart the contribution of a specific genetic lesion into the discrete aspects of impulsive behavior.

  15. The utility of rat models of impulsivity in developing pharmacotherapies for impulse control disorders

    PubMed Central

    Winstanley, Catharine A

    2011-01-01

    High levels of impulsive behaviours are a clinically significant symptom in a range of psychiatric disorders, such as attention deficit hyperactivity disorder, bipolar disorder, personality disorders, pathological gambling and substance abuse. Although often measured using questionnaire assessments, levels of different types of impulsivity can also be determined using behavioural tests. Rodent analogues of these paradigms have been developed, and similar neural circuitry has been implicated in their performance in both humans and rats. In the current review, the methodology underlying the measurement of different aspects of impulsive action and choice are considered from the viewpoint of drug development, with a focus on the continuous performance task (CPT), stop-signal task (SST), go/no-go and delay-discounting paradigms. Current issues impeding translation between animal and human studies are identified, and comparisons drawn between the acute effects of dopaminergic, noradrenergic and serotonergic compounds across species. Although the field could benefit from a more systematic determination of different pharmacological agents across paradigms, there are signs of strong concordance between the animal and human data. However, the type of impulsivity measured appears to play a significant role, with the SST and delay discounting providing more consistent effects for dopaminergic drugs, while the CPT and SST show better predictive validity so far for serotonergic and noradrenergic compounds. Based on the available data, it would appear that these impulsivity models could be used more widely to identify potential pharmacotherapies for impulse control disorders. Novel targets within the glutamatergic and serotonergic system are also suggested. LINKED ARTICLES This article is part of a themed issue on Translational Neuropharmacology. To view the other articles in this issue visit http://dx.doi.org/10.1111/bph.2011.164.issue-4 PMID:21410459

  16. Relationships of personality dimensions with impulsivity in alcohol-dependent inpatient men.

    PubMed

    Bozkurt, Muge; Evren, Cuneyt; Can, Yesim; Evren, Bilge; Cetingok, Sera; Yilmaz, Alkin

    2014-07-01

    Impulsivity is closely related to substance use and abuse, both as a contributor to use and as a consequence of use. Particular dimensions of temperament and character were reported to be associated with trait impulsivity in different populations. The aim of the present study was to evaluate the relationship of personality dimensions with impulsivity among men with alcohol dependence. Also we wanted to control the effect of depression and anxiety symptoms on this relationship. Participants were consecutively admitted male alcohol-dependent inpatients (n = 94) and healthy controls (n = 63). Patients were investigated with the Barratt Impulsiveness Scale, version 11 (BIS-11), the Temperament and Character Inventory (TCI) and the Symptom Checklist-Revised (SCL-90-R). Severity of impulsivity and dimensions of impulsivity were higher in alcohol-dependent inpatients than in healthy controls. Impulsivity was negatively correlated with reward dependence, persistence, self-directedness and cooperativeness, but positively correlated with novelty seeking, harm avoidance, depression and anxiety. Although high depression and temperament dimensions (high novelty seeking, harm avoidance and low reward dependence) predicted impulsivity, combinations of personality dimensions that predict dimensions of impulsivity differed. RESULTS may suggest that together with depression when impulsivity is the problem, both dimensions of impulsivity and personality must be eval