WorldWideScience

Sample records for specific impulse magnetoplasma

  1. Specific Impulse Definition for Ablative Laser Propulsion

    Science.gov (United States)

    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.

  2. Specific Impulse Definition for Ablative Laser Propulsion

    Science.gov (United States)

    Gregory, Don A.; Herren, Kenneth A.

    2005-04-01

    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.

  3. Ultrahigh Specific Impulse Nuclear Thermal Propulsion

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. 20mN, Variable Specific Impulse Colloid Thruster Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Colloid thrusters have long been known for their exceptional thrust efficiency and ability to operate over a range of specific impulse due to easily variable...

  5. Ablative laser propulsion: determination of specific impulse from plasma imaging

    Science.gov (United States)

    Lin, Jun; Thompson, M. S.; Pakhomov, Andrew V.

    2004-09-01

    This work summarizes the combination of experimental and digital image processing technique developed for determination of plasma expansion velocity angular profiles. Such profiles were used further for assessment of specific impulses for ablative laser propulsion. The technique uses time-resolved intensified charge-coupled device (ICCD) camera with 18 ns minimum time delay, 100 μm spatial resolution, and 5 ns gating speed. The plasma was formed in vacuum (~ 3x10-3 Torr) by focusing output pulses of a laser system (100-ps pulsewidth at 532 nm wavelength and ~35 mJ energy) on surfaces of C (graphite), Al, Si, Fe, Cu, Zn, Sn, and Pb targets. Plasma expansion velocity profiles were derived from plume edge contours. Specific impulse (Isp) was then deduced from the profiles. New Isp data appeared in excellent agreement with specific impulses derived from force measurements, conducted earlier. Observed angular profiles of plasma edge velocity and integral intensity are reported and discussed.

  6. Impulsivity.

    Science.gov (United States)

    Hollander, E; Rosen, J

    2000-01-01

    Disorders characterized by impulsivity include disorders of impulse control (intermittent explosive disorder, pyromania, kleptomania, pathological gambling and trichotillomania), paraphilias, sexual impulsions and sexual addictions and impulsive aggression personality disorders (borderline, antisocial, histrionic and narcissistic personality disorders). Impulsivity has a substantial impact on both individuals and society. Impulse control disorders may be conceptualized as a subset of the obsessive-compulsive spectrum. In this article, we examine the genetic and neurobiological aetiology of these disorders and possible treatment options. The link between serotonergic dysfunction and the pathophysiology of impulsivity is discussed, and studies that examine the efficacy of various selective serotonin reuptake inhibitors and other alternatives in the treatment of impulsive disorders such as pathological gambling, sexual addictions and borderline personality disorder are presented. PMID:10888030

  7. Coaxial plasma thrusters for high specific impulse propulsion

    Science.gov (United States)

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

    Science.gov (United States)

    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.

  9. Laser propulsion with a high specific impulse using a thin film propellant

    International Nuclear Information System (INIS)

    A new laser propulsion scheme with a high specific impulse is proposed in this paper. An extremely thin polyimide film is used as the propellant to eliminate thermal diffusion and sputter from the target material. It is found that a high specific impulse of 1520 s can be achieved at 1011-W/cm2 laser intensity because of economic use of the propellant. The influences of the laser intensity and the ablation area on the specific impulse are also studied in the experiment. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  10. Measurements of Laser Intensity Dependence of High Specific Impulse for Laser Ablative Propulsion

    International Nuclear Information System (INIS)

    One of the advantages of laser propulsion is the possibility of controlling exhaust velocity namely specific impulse and optimization of energy and propellant usage. Characteristics of laser plasma interaction with the incident laser intensities of 107?1010W/cm2 have been investigated using multiple plasma diagnostics such as ion collector. Electron temperatures will be discussed

  11. Measurements of Laser Intensity Dependence of High Specific Impulse for Laser Ablative Propulsion

    Science.gov (United States)

    Bato, Masafumi; Uchida, Shigeaki; Shimada, Yoshinori

    2004-03-01

    One of the advantages of laser propulsion is the possibility of controlling exhaust velocity namely specific impulse and optimization of energy and propellant usage. Characteristics of laser plasma interaction with the incident laser intensities of 107~1010W/cm2 have been investigated using multiple plasma diagnostics such as ion collector. Electron temperatures will be discussed.

  12. Resonance interaction of surface magnetoplasma polaritons in semiconductor layer

    International Nuclear Information System (INIS)

    Magnetoplasma polaritons in semiconductor layer with asymmetric dielectric surroundings are studied. Resonance interaction of surface magnetoplasma polaritons propagating on the opposite boundaries of the semiconductor layer is investigated. Quantitative criteria for the effect existence are determined

  13. Liquid-fueled, Laser-powered, N-class thrust Space Engine with Variable Specific Impulse

    Science.gov (United States)

    Phipps, Claude R.; Luke, James R.; Helgeson, Wesley

    2008-04-01

    We discuss the requirements for developing a lightweight laser-powered space engine with specific impulse range 200demanding maneuvers in short times, while generating the optimum specific impulse for each mission segment. We will address specific problems which have been solved. The first of these is fuel delivery to the laser focus. A pulsed laser format is required for reasons we will discuss. Solid-fuel configurations (such as the fuel tapes used in the Photonic Associates μLPT microthruster) are not amenable to the range of mass delivery rates (μg/s to mg/s) necessary for such an engine. Liquid fuels are suggested. However, liquids with ordinary viscosities splash under pulsed laser illumination, ruining engine performance by causing the majority of fuel mass to be ejected at low Isp. We have shown that Isp = 680 seconds can be achieved by a viscous fuel based on glycidyl azide polymer and an IR-dye laser absorber. The second problem is optics clouding from ablated material. This can be handled actively by a flowing gas system. The final problem is mass: we will present an engine design which fits within a 10-kg "dry mass" budget. The engine, 80 kg mass with fuel, is designed to fit within a 180-kg spacecraft, and use up 3 kW of prime power to deliver a Δv of 17.5 km/s to the spacecraft in sixteen months.

  14. Laser-powered multi-newton thrust space engine with variable specific impulse

    Science.gov (United States)

    Phipps, Claude R.; Luke, James R.; Helgeson, Wesley

    2008-05-01

    Recently we became interested in applying previous work with liquid fueled laser powered minithrusters for spacecraft orientation to the conceptual design of a multi-newton thruster based on the same principles. Solid-fuel configurations (such as the fuel tapes used in the Photonic Associates microthruster) are not amenable to the range of mass delivery rates (g/s to g/s) necessary for such an engine. We will discuss problems for this design which have been solved, including identifying a practical method of delivering liquid fuel to the laser focus, avoiding splashing of liquid fuels under pulsed laser illumination, and avoiding optics clouding due to ablation backstreaming on optical surfaces from the laser-fuel interaction region. We have already shown that Isp = 680 seconds can be achieved by a viscous liquid fuel based on glycidyl azide polymer and an IR-dye laser absorber. The final problem is mass: we will discuss a notional engine design which fits within a 10-kg "dry mass" budget. This engine, 80kg mass with fuel, is designed to fit within a 180-kg spacecraft, and use 3kW of prime power to deliver a Δv of 17.5 km/s to the spacecraft in sixteen months. Its specific impulse will be adjustable over the range 200demanding maneuvers in short times, while generating the optimum specific impulse for each mission segment. We see no reason why Isp = 10,000 seconds cannot be achieved with liquid fuels.

  15. Development of the 900 second specific impulse carbide low enriched uranium nuclear thermal rocket

    International Nuclear Information System (INIS)

    This study presents the Carbide Low Enriched Uranium Nuclear Thermal Rocket (LEU-NTR) in its latest form. First, a background on the design methodology is given along with a summary of previous work on the mass optimization of the core. The issue of the rather large power peaking is then raised and addressed through the implementation of radial enrichment zoning and increasing the radial reflector thickness. The advantages and disadvantages of each variation are then addressed before the issue of how to raise the coolant exit temperature is raised. Two methods to do so are then discussed and combined to produce three configurations of the Carbide LEU-NTR that operate with a specific impulse of 900 sec. Finally, the new performance characteristics are presented and compared with previous iterations of the design. (author)

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. Liquid-fueled, Laser-powered, N-class thrust Space Engine with Variable Specific Impulse

    International Nuclear Information System (INIS)

    We discuss the requirements for developing a lightweight laser-powered space engine with specific impulse range 200spsp. We have shown that Isp = 680 seconds can be achieved by a viscous fuel based on glycidyl azide polymer and an IR-dye laser absorber. The second problem is optics clouding from ablated material. This can be handled actively by a flowing gas system. The final problem is mass: we will present an engine design which fits within a 10-kg 'dry mass' budget.The engine, 80 kg mass with fuel, is designed to fit within a 180-kg spacecraft, and use up 3 kW of prime power to deliver a Δv of 17.5 km/s to the spacecraft in sixteen months

  19. Angular distributions of plasma edge velocity and integrated intensity: Update on specific impulse for Ablative Laser Propulsion

    International Nuclear Information System (INIS)

    This work concludes our discussion of the image processing technique developed earlier for determination of specific impulse (Isp) for Ablative Laser Propulsion (ALP). The plasma plumes are recorded with a time-resolved intensified charge-coupled device (ICCD) camera. The plasma was formed in vacuum (∼ 3x10-3 Torr) by focusing output pulses of a laser system (100-ps pulsewidth at 532 nm wavelength and ∼35 mJ energy) on surfaces of C (graphite), Al, Si, Fe, Cu, Zn, Sn, and Pb elements. Angular profiles for integrated intensity and plasma expansion velocity were determined for the tested elements. Such profiles were used further for assessment of specific impulse. Specific impulses derived from angular distributions of plasma expansion velocity and integral intensity appeared in excellent agreement with the data derived earlier from force measurements

  20. Angular distributions of plasma edge velocity and integrated intensity: Update on specific impulse for Ablative Laser Propulsion

    Science.gov (United States)

    Lin, Jun; Pakhomov, Andrew V.

    2005-04-01

    This work concludes our discussion of the image processing technique developed earlier for determination of specific impulse (Isp) for Ablative Laser Propulsion (ALP). The plasma plumes are recorded with a time-resolved intensified charge-coupled device (ICCD) camera. The plasma was formed in vacuum (˜ 3×10-3 Torr) by focusing output pulses of a laser system (100-ps pulsewidth at 532 nm wavelength and ˜35 mJ energy) on surfaces of C (graphite), Al, Si, Fe, Cu, Zn, Sn, and Pb elements. Angular profiles for integrated intensity and plasma expansion velocity were determined for the tested elements. Such profiles were used further for assessment of specific impulse. Specific impulses derived from angular distributions of plasma expansion velocity and integral intensity appeared in excellent agreement with the data derived earlier from force measurements.

  1. A POPULATION-SPECIFIC HTR2B STOP CODON PREDISPOSES TO SEVERE IMPULSIVITY

    Science.gov (United States)

    Bevilacqua, Laura; Doly, Stéphane; Kaprio, Jaakko; Yuan, Qiaoping; Tikkanen, Roope; Paunio, Tiina; Zhou, Zhifeng; Wedenoja, Juho; Maroteaux, Luc; Diaz, Silvina; Belmer, Arnaud; Hodgkinson, Colin A.; Dell’Osso, Liliana; Suvisaari, Jaana; Coccaro, Emil; Rose, Richard J; Peltonen, Leena; Virkkunen, Matti; Goldman, David

    2011-01-01

    SUMMARY Impulsivity, describing action without foresight, is an important feature of several psychiatric diseases, suicidality and violent behavior. The complex origins of impulsivity hinder identification of the genes influencing both it and diseases with which it is associated. We performed exon-centric sequencing of impulsive individuals in a founder population, targeting fourteen genes belonging to the serotonin and dopamine domain. A stop codon in HTR2B that is common (MAF >1%) but exclusive to Finns was identified. Expression of the gene in the human brain was assessed, as well as the molecular functionality of the stop codon that was associated with psychiatric diseases marked by impulsivity in both population and family-based analyses. Knockout of Htr2b increased impulsive behaviors in mice, indicative of predictive validity. Our study shows the potential for identifying and tracing effects of rare alleles in complex behavioral phenotypes using founder populations, and suggests a role for HTR2B in impulsivity. PMID:21179162

  2. A POPULATION-SPECIFIC HTR2B STOP CODON PREDISPOSES TO SEVERE IMPULSIVITY

    OpenAIRE

    Bevilacqua, Laura; Doly, Stéphane; Kaprio, Jaakko; Yuan, Qiaoping; Tikkanen, Roope; Paunio, Tiina; Zhou, Zhifeng; Wedenoja, Juho; Maroteaux, Luc; Diaz, Silvina,; Belmer, Arnaud; Hodgkinson, Colin; Dell'Osso, Liliana; Suvisaari, Jaana; Coccaro, Emil

    2010-01-01

    Impulsivity, describing action without foresight, is an important feature of several psychiatric diseases, suicidality and violent behaviour. The complex origins of impulsivity hinder identification of the genes influencing it and the diseases with which it is associated. Here we perform exon-focused sequencing of impulsive individuals in a founder population, targeting fourteen genes belonging to the serotonin and dopamine domain. A stop codon in HTR2B was identified that is common (minor al...

  3. Current collection in a magnetoplasma

    Science.gov (United States)

    Laframboise, Jim G.; Sonmor, L. J.

    1990-12-01

    The authors present a survey of a very incomplete subject, current collection in a magnetoplasma. The best-developed and simplest theories for current collection are steady-state collisionless theories, and these must be understood before departures from them can be analyzed usefully. Thus, the authors begin with a review of them. The authors include some recent numerical results which indicate that steady-state collisionless Laplace-limit currents remain substantially below the Parker-Murphy (1967) canonical upper bound out to very large electrode potentials, and approach it as a limit only very slowly if at all. Attempts to correct this theory for space-charge effects lead to potential disturbances which extend to infinite distance along the electrode's magnetic shadow, unless collisional effects are also taken into account. However, even a small amount of relative plasma drift motion, such as that involved in a typical rocket experiment, can change this conclusion fundamentally. It is widely believed that time-averaged current collection may be increased by effects of plasma turbulence, and the authors review the available evidence for and against this contention. Steady-state collisionless particle dynamics predicts the existence of a toroidal region of trapped orbits which surrounds the electrode. Light emissions from this region have been photographed, indicating that collisional ionization may also occur there, and this, and/or scattering by collisions or possibly turbulent fluctuations in this region, may also increase current collection by the electrode. The authors also discuss effects on particle motions near the electrode, associated with breakdown of magnetic insulation in the region of large electric fields near it.

  4. A population-specific HTR2B stop codon predisposes to severe impulsivity.

    Science.gov (United States)

    Bevilacqua, Laura; Doly, Stéphane; Kaprio, Jaakko; Yuan, Qiaoping; Tikkanen, Roope; Paunio, Tiina; Zhou, Zhifeng; Wedenoja, Juho; Maroteaux, Luc; Diaz, Silvina; Belmer, Arnaud; Hodgkinson, Colin A; Dell'osso, Liliana; Suvisaari, Jaana; Coccaro, Emil; Rose, Richard J; Peltonen, Leena; Virkkunen, Matti; Goldman, David

    2010-12-23

    Impulsivity, describing action without foresight, is an important feature of several psychiatric diseases, suicidality and violent behaviour. The complex origins of impulsivity hinder identification of the genes influencing it and the diseases with which it is associated. Here we perform exon-focused sequencing of impulsive individuals in a founder population, targeting fourteen genes belonging to the serotonin and dopamine domain. A stop codon in HTR2B was identified that is common (minor allele frequency > 1%) but exclusive to Finnish people. Expression of the gene in the human brain was assessed, as well as the molecular functionality of the stop codon, which was associated with psychiatric diseases marked by impulsivity in both population and family-based analyses. Knockout of Htr2b increased impulsive behaviours in mice, indicative of predictive validity. Our study shows the potential for identifying and tracing effects of rare alleles in complex behavioural phenotypes using founder populations, and indicates a role for HTR2B in impulsivity. PMID:21179162

  5. Overlapping and disease specific aspects of impulsivity in children and adolescents with schizophrenia spectrum disorders or Attention-Deficit/Hyperactivity Disorder

    DEFF Research Database (Denmark)

    Jepsen, Jens Richardt Møllegaard; Rydkjær, Jacob; Fagerlund, Birgitte; Pagsberg, Anne Katrine; Oranje, Bob; Glenthøj, Birte Yding

    Objectives: To identify disease specific and overlapping aspects of impulsivity in children and adolescents with early-onset schizophrenia spectrum disorders or ADHD. Methods: Motor impulsivity (Stop Signal Task), reflection impulsivity (Information Sampling Task), and trait impulsivity (Barratt...... Impulsiveness Scale) are compared between three groups of children and adolescents between 12 and 17 years of age: patients with early-onset schizophrenia spectrum disorders (N=29), patients with ADHD (N=29), and healthy controls (N=45). Results: Preliminary results: Reflection impulsivity is significantly...... increased in patients with ADHD but not in early-onset schizophrenia spectrum disorder patients who perform non-significantly different from the healthy controls in the decreased win condition. Discussion: Reduced information sampling in children and adolescents with ADHD may reflect an inability to delay...

  6. Nonlinear wave interactions in quantum magnetoplasmas

    International Nuclear Information System (INIS)

    Nonlinear interactions involving electrostatic upper-hybrid (UH), ion-cyclotron (IC), lower-hybrid (LH), and Alfven waves in quantum magnetoplasmas are considered. For this purpose, the quantum hydrodynamical equations are used to derive the governing equations for nonlinearly coupled UH, IC, LH, and Alfven waves. The equations are then Fourier analyzed to obtain nonlinear dispersion relations, which admit both decay and modulational instabilities of the UH waves at quantum scales. The growth rates of the instabilities are presented. They can be useful in applications of our work to diagnostics in laboratory and astrophysical settings

  7. Radiation pattern from a cold magnetoplasma antenna

    International Nuclear Information System (INIS)

    In this paper a theoretical study of the radiation pattern of an antenna build up from a confined magnetoplasma is made. Assuming that the electron gas is in the linear regime, we derived expressions for the conductivity tensor of the plasma and the radiated electromagnetic field under the influence of both dc magnetic and ac electric externally applied fields. It is found that the radiation patterns are dependent on the relative orientations of the applied fields and in the frequency of the applied electric field.

  8. Jeans stability in collisional quantum dusty magnetoplasmas

    Energy Technology Data Exchange (ETDEWEB)

    Jamil, M.; Asif, M. [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Mir, Zahid [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Faculty of Engineering and Technology, Superior University, Lahore 54000 (Pakistan); Salimullah, M. [Department of Physics, Jahangirnagar University, Savar, Dhaka 1342 (Bangladesh)

    2014-09-15

    Jeans instability is examined in detail in uniform dusty magnetoplasmas taking care of collisional and non-zero finite thermal effects in addition to the quantum characteristics arising through the Bohm potential and the Fermi degenerate pressure using the quantum hydrodynamic model of plasmas. It is found that the presence of the dust-lower-hybrid wave, collisional effects of plasma species, thermal effects of electrons, and the quantum mechanical effects of electrons have significance over the Jeans instability. Here, we have pointed out a new class of dissipative instability in quantum plasma regime.

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

    Science.gov (United States)

    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. Europa, in the Jovian system, is a high priority target for an outer Solar System exploration mission. More than a decade ago the Voyager spacecraft revealed Europa as a world swathed in ice and geologically young. NASA's Galileo spacecraft passed approximately 500 miles above the surface and provided detailed images of Europa's terrain marked by a dynamic topology that appeared to be remnants of ice volcanoes or geysers. The surface temperature averages a chilly -200° C. The pictures appear to show a relatively young surface of ice, possibly only 1 km thick in some places. Internal heating of Europa from Jupiter's tidal pull could form an ocean of liquid water beneath the surface. More recently, Ganymede and Callisto are believed to be ocean-bearing Jovian moons based on magnetometer measurements from the Galileo spacecraft. If liquid water exists, life may also. NASA plans to send an orbiting spacecraft to Europa to measure the thickness of the ice and to detect if an underlying liquid ocean exists. This mission would precede the proposed Europa Sample Return mission, which includes dispatching an autonomous submarine-like vehicle that could melt through the ice and explore the undersea realm. Because of the large energy requirements typical of these ambitious solar system science missions, use of chemical rockets results in interplanetary spacecraft that are prohibitive in terms of Initial Mass in Low- Earth Orbit (IMLEO) and cost. For example, using chemical rockets to return samples from Europa appears to be technically impractical, as it would require large delta V and launch vehicle capabilities. On the other hand, use of nuclear thermal rockets will significantly reduce IMLEO and, subsequently, costs. Moreover, nuclear thermal rockets can utilize extraterrestrial resources as propellants, an option not practical with chemical rockets. This "refueling" capability would enable nuclear rockets to carry out very high-energy missions, such as the return of large amounts of extraterrestrial material to Earth. The Europa missions considered in this proposal will be restricted to starting from LEO only after being placed in a stable orbit by a launch vehicle. This simplifies and eases the safety issues and mitigates political concerns. High propulsive efficiency of the MITEE engine yields the benefits of reduced transit time and a smaller launch vehicle.

  10. Potential coherent structures in nonuniform streaming dusty magnetoplasma

    Energy Technology Data Exchange (ETDEWEB)

    Vranjes, Jovo [Inst. of Physics, Belgrade (Yugoslavia); Shukla, Padma Kant [Ruhr-Universitaet Bochum, Institut fuer Theoretische Physik IV, Bochum (Germany)

    2001-07-01

    In this paper we study linear and nonlinear behaviour of modified convective cells and vortices in nonuniform dusty magnetoplasmas with perpendicular and parallel to the magnetic field plasma flows, and in basically two different physical systems, with stationary (corresponding to the case of ShuklaVarma mode) and nonstationary (i.e. taking part in perturbations) dust particles. For the case of stationary dust, by choosing some specific profiles for the sheared plasma flow and the dust density, we analyze the eigenvalue equation in order to deduce the growth rate. A threshold is also obtained for the wavenumber separating spatially damped and convective modes (growing in space) due to its interaction with the sheared plasma flow. In the nonlinear regime, for both stationary and nonstationary dust particles, and in the presence of various plasma flows perpendicular and parallel to the magnetic field lines, a variety of possible nonlinear solutions, driven by the nonuniform shear flow and dust density is presented, i.e., single and double vortex chains accompanied with zonal flows, and tripolar and global vortices. (author)

  11. Obliquely propagating magnetosonic waves in multicomponent quantum magnetoplasma

    International Nuclear Information System (INIS)

    Linear properties of obliquely propagating magnetosonic waves (both fast and slow) in multicomponent (electron-positron-ion (e-p-i) and dust-electron-ion (d-e-i)) quantum magnetoplasma are studied. It is found that the quantum Bohm potential term significantly changes the propagation of fast and slow magnetosonic waves in both e-p-i and d-e-i quantum plasmas. The variation of the dispersion characteristics with the increase/decrease of positron concentration in e-p-i and dust concentration in d-e-i quantum magnetoplasma is explored. Finally, the effect of angle θ (that the ambient magnetic field makes with the x-axis) on the dispersion properties of magnetosonic waves in multicomponent quantum magnetoplasma is investigated. The relevance of the present investigation to the dense astrophysical environments and microelectronic devices is also pointed out

  12. Instantaneous Impulses.

    Science.gov (United States)

    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)

  13. Mach cones in space and laboratory dusty magnetoplasmas

    International Nuclear Information System (INIS)

    We present a rigorous theoretical investigation on the possibility for the formation of Mach cones in both space and laboratory dusty magnetoplasmas. We find the parametric regimes for which different types of Mach cones, such as dust acoustic Mach cones, dust magneto-acoustic Mach cones, oscillonic Mach cones, etc. are formed in space and laboratory dusty magnetoplasmas. We also identify the basic features of such different classes of Mach cones (viz. dust- acoustic, dust magneto-acoustic, oscillonic Mach cones, etc.), and clearly explain how they are relevant to space and laboratory dusty manetoplasmas. (author)

  14. 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

    Science.gov (United States)

    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.

  15. Enhancement of D-T reaction rate in nonuniform magnetoplasma

    International Nuclear Information System (INIS)

    The rate of D-T reaction is calculated in nonuniform magnetoplasmas where the characteristic length of the spatial inhomogeneity perpendicular to the magnetic field is of the order of gyroradius. The probability of head-on collisions increases, when the guiding centers of the reactants are separated by the distance of the sum of the gyroradii. (author)

  16. Parametric excitation of acoustic waves in piezoelectric solid state magnetoplasma

    International Nuclear Information System (INIS)

    Absolute instability of the acoustic wave (excited parametrically) has been explored on the basis of the Bers and Briggs criterion in the presence of a large transverse static magnetic field. In the magnetoplasma threshold the electric field decreases to about 0.4 times the value at zero magnetic field. (Auth.)

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

    Science.gov (United States)

    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.

  18. Impulsive action: emotional impulses and their control.

    Science.gov (United States)

    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

  19. Impedance of a large circular loop antenna in a magnetoplasma

    International Nuclear Information System (INIS)

    The input impedance of a large circular loop antenna with arbitrary orientation in a cold magnetoplasma is calculated by using a transmission line theory. New impedance resonances for antennas of finite size in a magnetoplasma in the frequency region below and near the electron cyclotron frequency are indicated theoretically. The resonance peak of the impedance at the lower hybrid resonance frequency is also predicted to exist for arbitrarily oriented antennas of finite size. The experiments on the impedance of a large circular loop antenna are carried out for the cases of normal and parallel orientation of the magnetic field with respect to the plane of the loop immersed in a radio frequency-generated laboratory plasma. The newly predicted impedance resonances for the antenna of finite size are observed. It is also shown that the measured impedances agree fairly well with the calculated ones

  20. Experimental investigation of magnetoplasma acceleration of dielectric projectiles in a rail gun

    International Nuclear Information System (INIS)

    The authors present results of experimental investigations of the process of a nondestructive electrodynamic acceleration of dielectric projectiles in a magnetoplasma accelerator of rail gun type upon discharge of the electrical energy of the capacitor bank. They describe the phenomenon of decay of the plasma driving piston. They describe the causes of this phenomenon and the practical steps to avoid it. In a specific facility regimes have been achieved with electrodynamic acceleration of projectiles without plasma piston decay at working currents of up to 0.7 MA. In acceleration of projectiles of mass ? 1 g a speed of 6 km/sec has been attained and reproduced. The facility constructed can be used efficiently in experiments to investigate the thermophysical properties of substances using dynamic methods as a means of creating intense kinetic energy pulses

  1. Spin effect on parametric interactions of waves in magnetoplasmas

    International Nuclear Information System (INIS)

    The parametric decay instability of upper hybrid wave into low-frequency electromagnetic Shear Alfvén wave and Ordinary mode radiation (O-mode) has been investigated in an electron-ion plasma immersed in the uniform external magnetic field. Incorporating quantum effect due to electron spin, the fluid model has been used to investigate the linear and nonlinear response of the plasma species for three-wave coupling in a magnetoplasma. It is shown that the spin of electrons has considerable effect on the parametric decay of upper hybrid wave into Ordinary mode radiation (O-mode) and Shear Alfvén wave even in classical regime.

  2. Antiphased Cyclotron-Magnetoplasma Mode in a Quantum Hall System

    OpenAIRE

    Kulik, L. V.; Dickmann, S.; Drozdov, I. K.; Zhuravlev, I. S.; Kirpichev, V. E.; Kukushkin, I. V.; Schmult, S.; Dietsche, W.

    2008-01-01

    An antiphased magnetoplasma (MP) mode in a two-dimensional electron gas (2DEG) has been studied by means of inelastic light scattering (ILS) spectroscopy. Unlike the cophased MP mode it is purely quantum excitation which has no classic plasma analogue. It is found that zero momentum degeneracy for the antiphased and cophased modes predicted by the first-order perturbation approach in terms of the {\\it e-e} interaction is lifted. The zero momentum energy gap is determined by a negative correla...

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

    Directory of Open Access Journals (Sweden)

    Lindberg Nina

    2007-07-01

    Full Text Available Abstract 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.

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

    Science.gov (United States)

    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

  5. Current collection by probes and electrodes in space magnetoplasmas - A review

    Science.gov (United States)

    Laframboise, J. G.; Sonmor, L. J.

    1993-01-01

    The problem of predicting current collection by probes in space magnetoplasmas is addressed. Collisionless steady state theories are considered for the case of a spherical probe in a collisionless plasma containing a uniform magnetic field. The combined effects of space charge and collisions in space magnetoplasmas are examined, as are the effects of plasma turbulence. Particle trapping and the 'toroidal glow' region, the breakdown of magnetic insulation, and phenomena around large orbiting objects at high voltages are also discussed.

  6. Dispersion properties of compressional electromagnetic waves in quantum dusty magnetoplasmas

    Science.gov (United States)

    Ali, S.; Shukla, P. K.

    2006-05-01

    A new dispersion relation for low-frequency compressional electromagnetic waves is derived by employing quantum magnetohydrodynamic model and Maxwell equations in cold quantum dusty magnetoplasmas. The latter is composed of inertialess electrons, mobile ions, and immobile charged dust particulates. The dispersion relation for the low-frequency compressional electromagnetic modes is further analyzed for the waves propagating parallel, perpendicular, and oblique to the external magnetic field direction. It is found theoretically and numerically that the quantum parameter αq=(ni0/ne0)ℏ2/(4memi) affects the real angular frequencies and the phase speeds of the compressional electromagnetic modes. Here, ni0 (ne0) is the equilibrium number density of the ions (electrons), me (mi) is the electron (ion) mass, and ℏ is the Plank constant divided by 2π.

  7. Amplitude modulated drift wave packets in a nonuniform magnetoplasma

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, P.K., E-mail: profshukla@yahoo.de [International Centre for Advanced Studies in Physical Sciences and Institute for Theoretical Physics, Faculty of Physics and Astronomy, Ruhr University Bochum, D-447 80 Bochum (Germany); Misra, A.P., E-mail: apmisra@gmail.com [Department of Mathematics, Siksha Bhavana, Visva-Bharati University, Santiniketan 731 235 (India)

    2012-08-06

    We consider the amplitude modulation of low-frequency, long wavelength electrostatic drift wave packets in a nonuniform magnetoplasma with the effects of equilibrium density, electron temperature and magnetic field inhomogeneities. The dynamics of the modulated drift wave packet is governed by a nonlinear Schrödinger equation. The latter is used to study the modulational instability of a Stoke's wave train to a small longitudinal perturbation. It is shown that the drift wave packet is stable (unstable) against the modulation when the drift wave number lies in 0

  8. Electric field variability and classifications of Titan's magnetoplasma environment

    CERN Document Server

    Arridge, Chris; Guio, Patrick

    2011-01-01

    The atmosphere of Saturn's largest moon Titan is driven by photochemistry, charged particle precipitation from Saturn's upstream magnetosphere, and presumably by the diffusion of the magnetospheric field into the outer ionosphere, amongst other processes. Ion pickup, controlled by the upstream convection electric field, plays a role in the loss of this atmosphere. The interaction of Titan with Saturn's magnetosphere results in the formation of a flow-induced magnetosphere. The upstream magnetoplasma environment of Titan is a complex and highly variable system and significant quasi-periodic modulations of the plasma in this region of Saturn's magnetosphere have been reported. In this paper we quantitatively investigate the effect of these quasi-periodic modulations on the convection electric field at Titan. We show that the electric field can be significantly perturbed away from the nominal radial orientation inferred from Voyager 1 observations, and demonstrate that upstream categorisation schemes must be use...

  9. Thermal Management of Superconducting Electromagnets in VASIMR Thrusters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) engine currently being developed at NASA Johnson is an attractive technology for minimizing transit time...

  10. Magnetospheric substorm: Loss of the magnetoplasma equilibrium as a nonlinear dynamical bifurcation

    Science.gov (United States)

    Kropotkin, A. P.

    2012-04-01

    The fast onset of a substorm—a substorm "explosion"—is usually associated with the moment of stability loss of the magnetoplasma equilibrium in the geomagnetic tail. The origination of such a process either from the near-Earth part of the plasma sheet or from its remote part, which is highly stretched into the tail, is now being studied theoretically and verified experimentally (at the present time, in the THEMIS project). In the first case, the resulting disturbance must have the form of a ballooning mode; in the second case, of tearing perturbation. However, in both cases, this stability loss, i.e., a quick breakdown in the balance, replacing the slow quasi-static evolution of configuration, can only occur as a nonlinear process. Taking into account the specific properties of the configuration and possible disturbances in it, we indicate why such a process cannot be the previously proposed "substorm detonation." It is shown that a suitable mathematical model is a nonlinear dynamical bifurcation occurring on a small time scale, with a delay relative to the moment of passing the marginally stable state.

  11. Inductively coupled TI-MPD spacecraft electric propulsion. [thermionic magnetoplasma dynamic thruster design

    Science.gov (United States)

    Britt, E. J.; Clark, K. E.; Pawlik, E. V.

    1976-01-01

    A nuclear electric propulsion concept using a thermionic reactor inductively coupled to a magnetoplasma-dynamic (MPD) accelerator is described and the results of preliminary analyses are presented. In this system, the thermionic generating unit operates continuously at a power level of approximately 0.4 MW, while the MPD thruster operates intermittently at higher voltages and power levels. Energy storage is provided by building up a large current in an inductor. Periodically, the charging current is interrupted and the energy stored in the magnetic field of the inductor is utilized for a short duration thrust pulse. A typical thrust pulse is characterized by a power level of 1 to 4 MWe, a duration of 1 msec, and a duty cycle of approximately 20%. Results of the preliminary analysis show that approximately 85 to 90% of the power available from the thermionic converter array can be delivered to the MPD thruster for a nominal 400 kWe system with an inductive unit suitable for a flight vehicle. Optimized values of the total specific mass of the system including the thermionic reactor, the inductor, and the MPD thruster are estimated in the range of 23 to 24 kg/kWe.

  12. Bifurcation and Quasiperiodic Behaviors of Ion Acoustic Waves in Magnetoplasmas with Nonthermal Electrons Featuring Tsallis Distribution

    Science.gov (United States)

    Saha, Asit; Pal, Nikhil; Chatterjee, Prasanta

    2015-06-01

    Bifurcation and quasiperiodic behaviors of ion acoustic waves in electron-ion magnetoplasmas with nonthermal electrons featuring Cairns-Tsallis distribution have been investigated on the frameworks of non-perturbed and perturbed Kadomtsev-Petviashvili (KP) equations, respectively. Employing the reductive perturbation technique (RPT), we have derived the KP equation in electron-ion magnetoplasmas with nonthermal electrons featuring Cairns-Tsallis distribution. Bifurcations of ion acoustic traveling waves of the KP equation have been presented. Using the bifurcation theory of planar dynamical systems, the existence of solitary wave solutions and periodic traveling wave solutions has been established. Three analytical solutions of these waves have been derived depending on the system parameters. Considering an external periodic perturbation, we have presented the quasiperiodic behavior of ion acoustic waves in electron-ion magnetoplasmas.

  13. The Concept of the Pinch Helicon Magnetoplasma Thruster

    Science.gov (United States)

    Ribeiro, Celso

    2015-11-01

    A new concept of a high efficient electrodeless magnetoplasma-based electric thruster using a helicon plasma submitted to a pinch effect is proposed. This concept is intended to have high thrust for a short period, while reducing the plasma-wall contact. This proposal is highly suitable for rocket devices for faster satellites' orbital correction, a feasible way to lead manned missions into deep space, and for a more compact plasma sources for plasma materials for fusion studies. The pinch effect is created by a set of poloidal field coils placed around the insulating cylinder where the helical antenna is mounted. A pulsed current creates the pinch effect, which immediately insulates the plasma to the wall, thus reducing the perpendicular particle and energy losses. As a consequence, the axial flux, thus the thrust, should be increased because of particle balance. This may require an additional magnetic field produced by a single coil placed at the back of the helicon antenna (the gas entrance) to be acted during the pinch phase, leading to an unbalanced magnetic mirror-type configuration, therefore a net flux outwards. The combination with the double helicon structure may also maximize the efficiency. If everything is synchronized, there will be no gas or energy wasted, and the wall heat will be minimal, thus reducing the problems of material fatigue and failures, and making feasible the use of conventional materials.

  14. Laser pulse propagation in inhomogeneous magnetoplasma channels and wakefield acceleration

    International Nuclear Information System (INIS)

    Wakefield excitation in a preformed inhomogeneous parabolic plasma channel by an intense relativistic (?1019?W/cm2) circularly polarized Gaussian laser pulse is investigated analytically and numerically in the presence of an external longitudinal magnetic field. A three dimensional envelope equation for the evolution of the laser pulse is derived, which includes the effect of the nonparaxial and applied external magnetic field. A relation for the channel radius with the laser spot size is derived and examines numerically to see the external magnetic field effect. It is observed that the channel radius depends on the applied external magnetic field. An analytical expression for the wakefield is derived and validated with the help of a two dimensional particle in cell (2D PIC) simulation code. It is shown that the electromagnetic nature of the wakes in an inhomogeneous plasma channel makes their excitation nonlocal, which results in change of fields with time and external magnetic field due to phase mixing of the plasma oscillations with spatially varying frequencies. The magnetic field effect on perturbation of the plasma density and decreasing length is also analyzed numerically. In addition, it has been shown that the electron energy gain in the inhomogeneous parabolic magnetoplasma channel can be increased significantly compared with the homogeneous plasma channel

  15. Laser pulse propagation in inhomogeneous magnetoplasma channels and wakefield acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, B. S., E-mail: bs-phy@yahoo.com; Jain, Archana [Government College Kota, Kota 324001 (India); Jaiman, N. K. [Department of Pure and Applied Physics, University of Kota, Kota 324010 (India); Gupta, D. N. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Jang, D. G.; Suk, H. [Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Kulagin, V. V. [Sternberg Astronomical Institute of Moscow State University, Moscow 119992 (Russian Federation)

    2014-02-15

    Wakefield excitation in a preformed inhomogeneous parabolic plasma channel by an intense relativistic (?10{sup 19}?W/cm{sup 2}) circularly polarized Gaussian laser pulse is investigated analytically and numerically in the presence of an external longitudinal magnetic field. A three dimensional envelope equation for the evolution of the laser pulse is derived, which includes the effect of the nonparaxial and applied external magnetic field. A relation for the channel radius with the laser spot size is derived and examines numerically to see the external magnetic field effect. It is observed that the channel radius depends on the applied external magnetic field. An analytical expression for the wakefield is derived and validated with the help of a two dimensional particle in cell (2D PIC) simulation code. It is shown that the electromagnetic nature of the wakes in an inhomogeneous plasma channel makes their excitation nonlocal, which results in change of fields with time and external magnetic field due to phase mixing of the plasma oscillations with spatially varying frequencies. The magnetic field effect on perturbation of the plasma density and decreasing length is also analyzed numerically. In addition, it has been shown that the electron energy gain in the inhomogeneous parabolic magnetoplasma channel can be increased significantly compared with the homogeneous plasma channel.

  16. Anatomy of a SAR impulse response.

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Ion Acoustic Waves in an Alkali Magneto-Plasma

    International Nuclear Information System (INIS)

    By a series of experiments on ion wave propagation in a magneto-plasma of caesium ionized by surface ionization, the authors studied the effects due to collisions between ions and neutral particles, the mean plasma velocity, the ratio ? = Te/Ti of electron and ion temperatures and the non-linear behaviour of a collisionless plasma. In a machine called OPS using direct injection of caesium illuminating one emitter the effect of collisions between neutrals and ions has been studied. The ratio ? = Te/Ti of the electron and ion temperatures which is an important parameter for the propagation and damping of the ion waves can be easily modified by injection of helium into the machine. The variations of phase velocity and damping as functions of the frequency for different pressures of injected neutral gas show a change in the ion temperature, the mean plasma velocity and a continuous transition from the Landau damping to the collisionnal damping. A separation of the two zones, the first one where the ions are cooled and the other where the wave is propagating, allows the study of the Landau damping and the measurement of the ratio ?. A non-linear damping of the ion wave has been observed and studied. The classical Landau damping is found for the lower frequency range but as the distance of propagation is of the order of or larger than half a wavelength, the measured damping becomes less than the Landau damping rate, and amplitude modulation is observed. The pseudo-wavelength and the modulation rate are bound by the period and amplitude of the wave as is foreseen by a non-linear theory. We observed that the wave behaviour is similar to the effect obtained in mixing the ion wave and a fast wave which has been found in the experiments. (author)

  18. Linear and nonlinear low-frequency electrostatic waves in a nonuniform pair-ion-dust magnetoplasma

    International Nuclear Information System (INIS)

    Linear and nonlinear properties of the low-frequency (in comparison with the ion gyrofrequency) electrostatic oscillations in pair-ion-dust magnetoplasma are presented. In the linear limit, the Shukla-Varma mode is coupled with the ion oscillations while the nonlinearly coupled modes appear in the form of a dipolar or a monopolar vortex

  19. Modulationally stable envelope solitons in astrophysical magnetoplasmas with degenerate relativistic electrons

    Science.gov (United States)

    Irfan, M.; Ali, S.; Mirza, Arshad M.; Wang, Yunliang

    2015-12-01

    > and the quantum parameter significantly modify the profiles of the envelope magnetoacoustic solitons. The present results are important to understanding of the nonlinear dynamics of magnetoacoustic solitons in astrophysical dense magnetoplasmas (viz., white dwarfs, magnetars, neutron stars, etc.), where the relativistic degeneracy effects play a vital role in collective interactions.

  20. Nonlinear generation of zonal flows by ion-acoustic waves in a uniform magnetoplasma

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, Nitin [Department of Physics, Umea University, SE-90187 Umea (Sweden); Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Shukla, P.K., E-mail: ps@tp4.ruhr-uni-bochum.d [Department of Physics, Umea University, SE-90187 Umea (Sweden); Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

    2010-01-11

    It is shown that large-scale zonal flows (ZFs) can be excited by Reynolds stress of nonlinearly interacting random phase ion-acoustic waves (EIAWs) in a uniform magnetoplasma. Since ZFs are associated with poloidal sheared flows, they can tear apart short scale EIAW turbulence eddies, and hence contribute to the reduction of the cross-field turbulent transport in a magnetized plasma.

  1. Universal formula for the quasistatic second-order density perturbation by a cold magnetoplasma wave

    International Nuclear Information System (INIS)

    Using the general expression for the ponderomotive Hamiltonian, the quasi-static quasi-neutral density change caused by the ponderomotive force of a cold magnetoplasma wave of arbitrary frequency and polarization is obtained. This formula agrees with and extends previous results for unmagnetized and magnetized plasma

  2. Some questions of snf reprocessing at the stages of ionization and magnetoplasma separation in crossed fields

    International Nuclear Information System (INIS)

    Possible composition of spent nuclear fuel (SNF) before and after the thermal separation stage is shown. The possibility of SNF purification from fission products (FP) at the ionization stage is analyzed. Trajectories of charged particles - molecular ions, FP and nuclear fuel, remained in SNF, at magnetoplasma separation stage are calculated

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

    International Nuclear Information System (INIS)

    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 FeCu alloy layers were synthesized. The results of our investigation revealed a nanocrystalline structure of the layers. The differences in the phase composition of the FeCu alloy layers produced by these two methods were observed. The synthesis of the FeCu 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 FeCu 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.

  4. Electron parallel velocity and temperature gradient driven electrostatic fluctuations in nonuniform magnetoplasmas

    Science.gov (United States)

    Shukla, P. K.; Coppi, B.; Eliasson, B.

    2007-01-01

    The combined effects of the electron-temperature (ET) and parallel electron velocity (PEV) gradients on electrostatic instabilities in a nonuniform magnetoplasma are investigated. For this purpose, a hybrid approach is used, in which the electrons are treated as a magnetized fluid, while the ions are described by means of a kinetic description. A new dispersion relation is derived, which shows how different plasma modes are linear coupled in the presence of the ET and PEV gradients. The dispersion relation is analyzed analytically (numerically) to demonstrate the instability of long- and short-wavelength electrostatic modes (to examine the combined effects of ET and PEV gradients) in nonuniform magnetoplasmas. The present results may be useful in understanding the salient features of nonthermal fluctuations and associated anomalous cross-field electron fluxes in forthcoming laboratory experiments.

  5. Theoretical analysis of the resonance cone in an inhomogeneous magnetoplasma column

    International Nuclear Information System (INIS)

    The three dimensional behaviour of the high frequency resonance cone is investigated using an inhomogeneous slab magnetoplasma model under the quasistatic approximation and neglecting ion motion. The effects of finite k sub(y) and electron thermal motion are considered numerically, revealing that the cone angle is shifted to a slightly smaller angle and the reflection point also shifts toward the high density region compared with the results under the cold plasma approximation. (author)

  6. Growth of laser ripple in a collisional magnetoplasma and its effect on plasma wave excitation

    International Nuclear Information System (INIS)

    Growth of a radially symmetrical ripple, superimposed on a Gaussian laser beam in collisional magnetoplasma is investigated. The effect of the magnetic field and the intensity of the laser on the growth of ripple is presented. Furthermore, the effect of the growing ripple on the excitation of an electron plasma wave has also been studied. The combined effect of increased intensity and magnetic field is observed to suppress the growth of ripple as well as the excitation of the plasma wave. (author)

  7. Dispersion of Volume Relativistic Magnetoplasma Excitation in a Gated Two-Dimensional Electron System

    OpenAIRE

    Gusikhin, P. A.; Muravev, V. M.; Kukushkin, I. V.

    2015-01-01

    The dispersion of the volume relativistic magnetoplasma mode in a gated GaAs/AlGaAs quantum well is measured using a coupled resonators detection technique. The weakly damped relativistic mode exhibits an unusual zigzag-shaped magnetodispersion dependence dictated by the diagonal component of the resistivity tensor $\\rho_{xx}$. The plasma excitation easily hybridizes with photon modes due to a large spatial delocalization of its electromagnetic field. The effects of electron density and struc...

  8. On the mechanism of a plasma focus formation in an ablation type magnetoplasma compressor

    International Nuclear Information System (INIS)

    The formation of a plasma focus was experimentally investigated in an annular magnetoplasma accelerator, the plasma being created from ablated material. The focus formation was shown to be a two-stage process independent of the plasma chemical composition, namely: stage (1) a 'Hall squeezing' of the plasma in the interelectrode space towards the central electrode (cathode), and stage (2) the pinching of the plasma in the space behind the center electrode. (Auth.)

  9. Rethinking Impulsivity in Suicide

    Science.gov (United States)

    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,…

  10. Impulsive prion disease model

    Directory of Open Access Journals (Sweden)

    Lakmeche Abdelkader

    2015-01-01

    Full Text Available A model of prion diseases with impulse effects is studied in this work. First we transform the model to a system of three differential equations with impulse effects in order to study the stability of periodic solution. After that we study the general model by the mean of evolution semi group in order to find conditions of existence of mild solution.

  11. A Neurogenetic Approach to Impulsivity

    OpenAIRE

    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 mole...

  12. Risk Factors and Impulsivity in Obesity

    Directory of Open Access Journals (Sweden)

    Bilge Burcak Annagur

    2010-12-01

    Full Text Available In addition to genetic tendency, social, cultural, emotional and diet-related factors play important role in the development of obesity. Impulsivity is the possible predictor of relapse in obesity treatment. Impulsivity is also considered as a predicting factor among patients who quit the treatment. Research has shown that obese people are more impulsive than other people. Impulsive features are especially found to be higher with those who have binge eating disorder. Impulsive people appears to have no control over their behaviors on eating and they have more interest towards food with higher calories. Another issue that strengthens the assocaition between obesity and impulsivity is the obesity in children with attention deficit hyperactivity disorder. Dopaminergic deficiency in the reward centre of the brain can be a common pathway for both attention deficit and obesity. Several approaches have been searched and put forward to sustain the patients lost weights after diet. Specific cognitive behavioral approaches developed for the treatment of impulsive behavior could contribute much into obesity treatment . Obesity is a chronic disease that requires long term treatment and follow up.

  13. Multidimensional examination of impulsivity in relation to disordered gambling.

    Science.gov (United States)

    Mackillop, James; Miller, Joshua D; Fortune, Erica; Maples, Jessica; Lance, Charles E; Campbell, W Keith; Goodie, Adam S

    2014-04-01

    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, 4 latent factors were identified among 19 indices and were designated reward sensitivity, punishment sensitivity, delay discounting, and cognitive impulsivity. All 4 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 4 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

  14. An impulsive bathtub vortex

    Science.gov (United States)

    Tyvand, Peder A.; Haugen, Kjetil B.

    2005-06-01

    The impulsive free-surface flow due to a point sink at the bottom of a container with rotating inviscid fluid is investigated analytically by a small-time expansion. Before the sink is turned on impulsively, there is a steady rigid-body rotation with large Rossby number (small angular velocity). The theory is developed to first order in the inverse Rossby number. The evolution of the free-surface vorticity is investigated. The azimuthal surface velocity is a cubic function of time. It is shown that the influence of the rotation of the earth on an impulsive bathtub vortex is negligible.

  15. A quantum hydrodynamic model for multicomponent quantum magnetoplasma with Jeans term

    International Nuclear Information System (INIS)

    The effect of Jeans term in a multicomponent self-gravitating quantum magnetoplasma is investigated employing the quantum hydrodynamic (QHD) model. The effects of quantum Bohm potential and statistical terms as well as the ambient magnetic field are also investigated on both dust and ion dynamics driven waves in this Letter. We state the conditions that can drive the system unstable in the presence of Jeans term. The limiting cases are also presented. The present work may have relevance in the dense astrophysical environments where the self-gravitating effects are expected to play a pivotal role

  16. Magnetoplasma excitations of two-dimensional anisotropic heavy fermions in AlAs quantum wells

    OpenAIRE

    Muravev, V. M.; Khisameeva, A. R.; Belyanin, V. N.; Kukushkin, I. V.; Tiemann, L; Reichl, C.; Dietsche, W.; Wegscheider, W

    2015-01-01

    The spectra of plasma and magnetoplasma excitations in a two-dimensional system of anisotropic heavy fermions were investigated for the first time. The spectrum of microwave absorption by disk-like samples of stressed AlAs quantum wells at low electron densities showed two plasma resonances separated by a frequency gap. These two plasma resonances correspond to electron mass principle values of $(1.10 \\pm 0.05) m_0$ and $(0.20 \\pm 0.01) m_0$. The observed results correspond to the case of a s...

  17. Properties of solitary ion acoustic waves in a quantized degenerate magnetoplasma with trapped electrons

    Energy Technology Data Exchange (ETDEWEB)

    Tsintsadze, N. L.; Tagviashvili, M. N. [Faculty of Exact and Natural Sciences, Andronikashvili Institute of Physics, Tbilisi State University, Tbilisi 0128, Georgia (United States); Shah, H. A. [Department of Physics, Forman Christian College, Ferozepur Road, Lahore 54600 (Pakistan); Qureshi, M. N. S. [Department of Physics, GC University, Katchery Road, Lahore 54000 (Pakistan)

    2015-02-15

    We have undertaken the investigation of ion acoustic solitary waves in both weakly and strongly quantized degenerate magnetoplasmas. It is seen that a singular point clearly demarcates the regions of weak and strong quantization due to the ambient magnetic field. The effect of the magnetic field is taken into account via the parameter ??{sub 0}=??{sub ce}/?{sub Fe} and the Mach number, and their effect on the formation of solitary structures is investigated in both cases and some results are presented graphically.

  18. Impulsivity and Sensation Seeking in Alcohol Abusing Patients with Schizophrenia

    OpenAIRE

    AlainDervaux; Jean-Pierre Olié

    2010-01-01

    Objective: Some studies have found that high levels of impulsivity and sensation seeking, particularly disinhibition are associated with substance abuse in patients with schizophrenia, as in the general population. However, no study has assessed impulsivity and sensation seeking specifically in schizophrenia patients with alcohol abuse or dependence. Materials and methods: We compared impulsivity and sensation seeking in a group of schizophrenia patients (DSM-III-R criteria) with lifetime alc...

  19. Optically measured explosive impulse

    Science.gov (United States)

    Biss, Matthew M.; McNesby, Kevin L.

    2014-06-01

    An experimental technique is investigated to optically measure the explosive impulse produced by laboratory-scale spherical charges detonated in air. Explosive impulse has historically been calculated from temporal pressure measurements obtained via piezoelectric transducers. The presented technique instead combines schlieren flow visualization and high-speed digital imaging to optically measure explosive impulse. Prior to an explosive event, schlieren system calibration is performed using known light-ray refractions and resulting digital image intensities. Explosive charges are detonated in the test section of a schlieren system and imaged by a high-speed digital camera in pseudo-streak mode. Spatiotemporal schlieren intensity maps are converted using an Abel deconvolution, Rankine-Hugoniot jump equations, ideal gas law, triangular temperature decay profile, and Schardin's standard photometric technique to yield spatiotemporal pressure maps. Temporal integration of individual pixel pressure profiles over the positive pressure duration of the shock wave yields the explosive impulse generated for a given radial standoff. Calculated explosive impulses are shown to exhibit good agreement between optically derived values and pencil gage pressure transducers.

  20. Evaluating Eve: visceral states influence the evaluation of impulsive behavior.

    Science.gov (United States)

    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. PMID:17605590

  1. High-power ultraviolet paraterphenyl-solution laser excited by the plasma focus of a magnetoplasma compressor

    International Nuclear Information System (INIS)

    High-power ultraviolet laser action was obtained in the 339-345 nm range by exciting an ethanol solution of paraterphenyl with a plasma focus of a magnetoplasma compressor in a vacuum approx.10-6 Torr. At 1710 J energy input to the discharge, the lasing energy was 2.6 J and the generated power was 26 MW

  2. The parametric decay of dust ion acoustic waves in non-uniform quantum dusty magnetoplasmas

    International Nuclear Information System (INIS)

    The parametric decay instability of a dust ion acoustic wave into low-frequency electrostatic dust-lower-hybrid and electromagnetic shear Alfven waves has been investigated in detail in an inhomogeneous cold quantum dusty plasma in the presence of external/ambient uniform magnetic field. The quantum magnetohydrodynamic model of plasmas with quantum effect arising through the Bohm potential and Fermi degenerate pressure has been employed in order to find the linear and nonlinear responses of the plasma particles for three-wave nonlinear coupling in a dusty magnetoplasma. A relatively high frequency electrostatic dust ion acoustic wave has been taken as the pump wave. It couples with two other low-frequency internal possible modes of the dusty magnetoplasma, viz., the dust-lower-hybrid and shear Alfven waves. The nonlinear dispersion relation of the dust-lower-hybrid wave has been solved to obtain the growth rate of the parametric decay instability. The growth rate is at a maximum for a small value of the external magnetic field B0. It is noted that the growth rate is proportional to the unperturbed electron number density noe and is independent of inhomogeneity beyond Le=2 cm. An extraordinary growth rate is observed with the quantum effect.

  3. Amplitude modulation of hydromagnetic waves and associated rogue waves in magnetoplasmas.

    Science.gov (United States)

    Sabry, R; Moslem, W M; Shukla, P K

    2012-09-01

    It is shown that the dynamics of amplitude-modulated compressional dispersive Alfvénic (CDA) waves in a collisional megnetoplasma is governed by a complex Ginzburg-Landau (CGL) equation. The nonlinear dispersion relation for the modulational instability of the CDA waves is derived and investigated numerically. It is found that the growth rate of the modulational instability decreases (increases) with the increase of the normalized electron-ion collision frequency α (the plasma β). The modulational instability criterion for the CGL equation is defined precisely and investigated numerically. The region of the modulational instability becomes narrower with the increase of α and β, indicating that the system dissipates the wave energy by collisions, and a stable CDA wave envelope packet in the form of a hole will be a dominant localized pulse. For a collisionless plasma, i.e., α=0, the CGL equation reduces to the standard nonlinear Schrödinger (NLS) equation. The latter is used to investigate the modulational (in)stability region for the CDA waves in a collisionless magnetoplasma. It is shown that, within unstable regions, a random set of nonlinearly interacting CDA perturbations leads to the formation of CDA rogue waves. In order to demonstrate that the characteristics of the CDA rogue waves are influenced by the plasma β, the relevant numerical analysis of the appropriate nonlinear solution of the NLS equation is presented. The application of our investigation to space and laboratory magnetoplasmas is discussed. PMID:23031035

  4. Modulation of drift-wave envelopes in a nonuniform quantum magnetoplasma

    Energy Technology Data Exchange (ETDEWEB)

    Misra, A. P., E-mail: apmisra@visva-bharati.ac.in, E-mail: apmisra@gmail.com [Department of Mathematics, Siksha Bhavana, Visva-Bharati University, Santiniketan-731 235, West Bengal (India)

    2014-04-15

    We study the amplitude modulation of low-frequency, long-wavelength electrostatic drift-wave envelopes in a nonuniform quantum magnetoplasma consisting of cold ions and degenerate electrons. The effects of tunneling associated with the quantum Bohm potential and the Fermi pressure for nonrelativistic degenerate electrons, as well as the equilibrium density and magnetic field inhomogeneities are taken into account. Starting from a set of quantum magnetohydrodynamic equations, we derive a nonlinear Schrödinger equation (NLSE) that governs the dynamics of the modulated quantum drift-wave packets. The NLSE is used to study the modulational instability (MI) of a Stoke's wave train to a small plane wave perturbation. It is shown that the quantum tunneling effect as well as the scale length of inhomogeneity plays crucial roles for the MI of the drift-wave packets. Thus, the latter can propagate in the form of bright and dark envelope solitons or as drift-wave rogons in degenerate dense magnetoplasmas.

  5. Relativistic impulse dynamics.

    Science.gov (United States)

    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 (Mller, 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. PMID:21929132

  6. Impulsivity, Risk Taking, and Timing

    OpenAIRE

    Baumann, Ana A; Odum, Amy. L.

    2012-01-01

    This study examined the relations among measures of impulsivity and timing. Impulsivity was assessed using delay and probability discounting, and self-report impulsivity (as measured by the Barratt Impulsiveness Scale; BIS-11). Timing was assessed using temporal perception as measured on a temporal bisection task and time perspective (as measured by the Zimbardo Time Perspective Inventory). One hundred and forty three college students completed these measures in a computer laboratory. The deg...

  7. Impulsive predator-prey model

    OpenAIRE

    Charif Fayssal; Helal Mohamed; Lakmeche Abdelkader

    2015-01-01

    In this paper we considered a predator-prey model with state-dependent impulse. We determine periodic solutions for the model without impulses and we prove the existence of nontrivial periodic solution in the case of impulse depending on the state of the model.

  8. Finite impulse response estimator

    Science.gov (United States)

    Kim, Kwang H.; Shafai, Bahram

    1990-10-01

    An attempt is made to combine a deterministic digital filter and a stochastic filter. The state equation is the standard form used for a Kalman filter derivation and the output equation is of the finite impulse response filter. An optimal estimator is derived for this combined structure, called a finite impulse response estimator (FIRE) which permits processing of a signal contaminated by deterministic and random noises. Derivation of the FIRE utilizes the state augmentation technique and the innovation technique. The proposed method is straight forward and easy to implement and it can be applied to areas such as time varying signal processing or target tracking where radar 'returns are contaminated by low frequency noises. Full derivation and a tracking application are presented.

  9. Micropower impulse radar imaging

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Impulsive consumer behavior

    OpenAIRE

    Kovač Žnideršić, Ružica; Grubor, Aleksandar; Marić, Dražen

    2014-01-01

    Research into consumer behaviour features as the foundation of all the planned and implemented marketing activities of a company. Consumer behaviour is determined by numerous factors, and is therefore characterised as highly complex and difficult to predict. A particular challenge for marketing science and practice is to research impulse consumer behaviour in shopping – a behaviour that occurs when consumers experience a sudden, powerful and persistent urge to buy something immediately. This ...

  11. Laboratory experiments on current flow between stationary and moving electrodes in magnetoplasmas

    Science.gov (United States)

    Stenzel, Reiner L.; Urrutia, J. M.

    1990-01-01

    Laboratory experiments were performed in order to investigate the basic physics of current flow between tethered electrodes in magnetoplasmas. The major findings are summarized. The experiments are performed in an effectively very large laboratory plasma in which not only the nonlinear current collection is addressed but also the propagation and spread of currents, the formation of current wings by moving electrodes, the current closure, and radiation from transmission lines. The laboratory plasma consists of a pulsed dc discharge whose Maxwellian afterglow provides a quiescent, current-free uniform background plasma. Electrodes consisting of collectors and electron emitters are inserted into the plasma and a pulsed voltage is applied between two floating electrodes via insulated transmission lines. Besides the applied current in the wire, the total current density in the plasma is obtained from space and time resolved magnetic probe measurements via Maxwell's law. Langmuir probes yield the plasma parameters.

  12. Electric dipole radiation at VLF in a uniform warm magneto-plasma.

    Science.gov (United States)

    Wang, T. N. C.; Bell, T. F.

    1972-01-01

    Use of a linear full electromagnetic wave theory to calculate the input impedance of an electric antenna embedded in a uniform, lossless, unbounded warm magnetoplasma, which is assumed to consist of warm electrons and cold ions. In calculating the dipole radiation resistance for the thermal modes and the thermally modified whistler mode the analysis includes the finite temperature only for the electrons. In deriving the formal solution of the warm plasma dipole input impedance a full-wave analysis is used and two antenna orientations are considered, parallel and perpendicular to the static magnetic field. A general dispersion equation governing the modes of propagation is derived and a detailed analysis is made of the propagation characteristics of these modes.

  13. Exact current to a spherical electrode in a collisionless, large-Debye-length magnetoplasma

    Science.gov (United States)

    Sonmor, L. J.; Laframboise, J. G.

    1991-09-01

    Calculations of the steady-state current collected by a spherical probe from a collisionless Maxwellian magnetoplasma are presented, which are exact in the limit of large Debye length. It is found that the electron current decreases as the electron potential increases from space potential with magnetic-field strength fixed. The ion current also diverges immediately from the adiabatic-limit current. For small fixed electrode potentials, the attracted-species current approaches monotonically the adiabatic-limit current as the magnetic field strength increases. For large electrode potentials this pattern reverses, i.e., the current monotonically approaches the canonical upper bound as the magnetic-field strength increases. It is inferred that, for large electrode potentials, the effect of decreasing the Debye length may be to reduce the current, as in the nonmagnetic case.

  14. Fully nonlinear ion-sound waves in a dense Fermi magnetoplasma

    International Nuclear Information System (INIS)

    The nonlinear propagation of ion-sound waves in a collisionless dense electron-ion magnetoplasma is investigated. The inertialess electrons are assumed to follow a non-Boltzmann distribution due to the pressure for the Fermi plasma and the ions are described by the hydrodynamic (HD) equations. An energy balance-like equation involving a new Sagdeev-type pseudo-potential is derived in the presence of the quantum statistical effects. Numerical calculations reveal that the profiles of the Sagdeev-like potential and the ion-sound density excitations are significantly affected by the wave direction cosine and the Mach number. The present studies might be helpful to understand the excitation of nonlinear ion-sound waves in dense plasmas such as those in superdense white dwarfs and neutron stars as well as in intense laser-solid density plasma experiments

  15. Propagation of nonlinear coherent structures in a collisional magnetoplasma with nonthermal electrons and finite ion temperature

    International Nuclear Information System (INIS)

    Nonlinear electrostatic waves in dissipative magnetized electron-ion (e-i) plasmas are investigated employing the two fluid model. In this regard, Zakharov Kuznetsov Burgers (ZKB) equation is derived using the small amplitude perturbation expansion method. It is observed that the nonthermal electron population, obliqueness, ion thermal effects, and kinematic viscosity significantly alter the structure of obliquely propagating nonlinear ion acoustic shock waves in dissipative e-i magnetoplasmas. It is observed that the system can admit both compressive and rarefactive shocks. The condition for the formation of both types of shocks is also given. The present study may be useful to understand the nonlinear propagation characteristics of electrostatic shock structures in space environments where the nonthermal electrons have been observed by various satellite missions such as Voyager and Freja.

  16. Specific Mass Estimates for A Vapor Core Reactor With MHD

    International Nuclear Information System (INIS)

    This study investigated the development of a system concept for space power generation and nuclear electric propulsion based on a vapor core reactor (VCR) with magnetohydrodynamic (MHD) power conversion system, coupled to a magnetoplasma-dynamic (MPD) thruster. The VCR is a liquid-vapor core reactor concept operating with metallic uranium or uranium tetrafluoride (UF4) vapor as the fissioning fuel and alkali metals or their fluorides as working fluid in a closed Rankine cycle with MHD energy conversion. Gaseous and liquid-vapor core reactors can potentially provide the highest reactor and cycle temperature among all existing or proposed fission reactor designs. This unique feature makes this reactor concept a very natural and attractive candidate for very high power (10 to 1000 MWe) and low specific mass (0.4 to 5 kg/kWe) nuclear electric propulsion (NEP) applications since the MHD output could be coupled with minimal power conditioning to MPD thrusters or other types of thruster for producing thrust at very high specific impulse (Isp 1500 to 10,000 s). The exceptional specific mass performance of an optimized VCRMHD- NEP system could lead to a dramatic reduction in the cost and duration of manned or robotic interplanetary as well as interstellar missions. The VCR-MHD-NEP system could enable very efficient Mars cargo transfers or short (<8 month) Mars round trips with less initial mass in low Earth orbit (IMLEO). The system could also enable highly efficient lunar cargo transfer and rapid missions to other destinations throughout the solar system. (authors)

  17. Reflection and transmission of light waves from the air-magnetoplasma interface: Spatial and angular Imbert-Fedorov shifts

    Energy Technology Data Exchange (ETDEWEB)

    Borhanian, Jafar, E-mail: borhanian@uma.ac.ir [Department of Physics, Faculty of Science, University of Mohaghegh Ardabili, P. O. Box 179, Ardabil (Iran, Islamic Republic of)

    2015-03-15

    We have investigated the reflection and transmission of an electromagnetic wave from the air-magnetoplasma interface. The reflection and transmission coefficients are obtained for an arbitrary polarized incident wave. The spatial and angular Imbert-Fedorov (IF) shifts are discussed. The numerical results are presented to study the dependence of the reflection and transmission coefficients and IF shifts on relevant parameters of the system. The plasma and wave parameters can be used to control the reflection coefficients and IF shifts.

  18. Reflection and transmission of light waves from the air-magnetoplasma interface: Spatial and angular Imbert-Fedorov shifts

    International Nuclear Information System (INIS)

    We have investigated the reflection and transmission of an electromagnetic wave from the air-magnetoplasma interface. The reflection and transmission coefficients are obtained for an arbitrary polarized incident wave. The spatial and angular Imbert-Fedorov (IF) shifts are discussed. The numerical results are presented to study the dependence of the reflection and transmission coefficients and IF shifts on relevant parameters of the system. The plasma and wave parameters can be used to control the reflection coefficients and IF shifts

  19. Physical Principles of Operation of a Two-Stage Light Gas Magnetoplasma Launcher for High-Vacuum Ballistic Tests

    Science.gov (United States)

    Khramtsov, P. P.; Penyazkov, O. G.; Vasetskii, V. A.; Grishchenko, V. M.; Makhnach, A. I.; Shikh, I. A.

    2015-09-01

    The results of experimental and theoretical investigations of the operation and a two-stage light gas magnetoplasma launcher are presented. An optical method for measuring the velocity of small bodies (2-10 mm) has been developed and used in testing a combined gas discharger for micro- and macroparticle acceleration. The experimental results are in good agreement with the mathematical model of the two-stage light gas gun in the approximation of constancy of the accelerating pressure behind the striker.

  20. Dependent heroin use and associated risky behaviour: the role of rash impulsiveness and reward sensitivity.

    Science.gov (United States)

    Dissabandara, Lakal O; Loxton, Natalie J; Dias, Shavindra R; Dodd, Peter R; Daglish, Mark; Stadlin, Alfreda

    2014-01-01

    Impulsive temperament has long been considered as a risk factor for substance use disorders (SUD). Considering the heterogeneity of impulsivity, a biologically-based 2-factor model incorporating reward sensitivity and rash impulsiveness facets, has been proposed. Here we report how these two facets of impulsiveness could be associated with different aspects of dependent heroin use and associated risky behaviour. Two hundred and ninety three dependent heroin users and 232 non-users were assessed on reward sensitivity, rash impulsivity, and the related trait of punishment sensitivity. After adjusting for multiple comparisons, heroin users were found to be more rash-impulsive and reward-sensitive than non-users (pdrug use. While greater impulsivity is a common trait in drug users compared with non-users, the use of a 2-factor model of impulsivity provides additional information regarding specific aspects of drug initiation and maintenance that can be targeted in the prevention and treatment of heroin dependence. PMID:24112954

  1. Dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Asit, E-mail: asit-saha123@rediffmail.com, E-mail: prasantachatterjee1@rediffmail.com [Department of Mathematics, Sikkim Manipal Institute of Technology, Majitar, Rangpo, East-Sikkim 737136 (India); Department of Mathematics, Siksha Bhavana, Visva Bharati University, Santiniketan-731235 (India); Pal, Nikhil; Chatterjee, Prasanta, E-mail: asit-saha123@rediffmail.com, E-mail: prasantachatterjee1@rediffmail.com [Department of Mathematics, Siksha Bhavana, Visva Bharati University, Santiniketan-731235 (India)

    2014-10-15

    The dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons has been investigated in the framework of perturbed and non-perturbed Kadomtsev-Petviashili (KP) equations. Applying the reductive perturbation technique, we have derived the KP equation in electron-positron-ion magnetoplasma with kappa distributed electrons and positrons. Bifurcations of ion acoustic traveling waves of the KP equation are presented. Using the bifurcation theory of planar dynamical systems, the existence of the solitary wave solutions and the periodic traveling wave solutions has been established. Two exact solutions of these waves have been derived depending on the system parameters. Then, using the Hirota's direct method, we have obtained two-soliton and three-soliton solutions of the KP equation. The effect of the spectral index κ on propagations of the two-soliton and the three-soliton has been shown. Considering an external periodic perturbation, we have presented the quasi periodic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas.

  2. Impulse control in developing brain

    OpenAIRE

    Lau, Miu-ching, Adelina.; 劉妙貞.

    2012-01-01

    Impulsivity is a complex, multifaceted domain with cognitive (level of attention), affective (emotion regulation) and behavioural (reward responsiveness) manifestations. No study had been done so far on trajectory of impulse control, attention and reward responsiveness in child development. The aim of the present study is to compare the level of impulsivity, attention and reward responsiveness among children at different stages of development. Forty Chines...

  3. Impulse Detectors for Noised Sequences

    Directory of Open Access Journals (Sweden)

    R. Lukac

    2001-06-01

    Full Text Available This paper is focused on a problem of impulse detection in thedynamic image environments corrupted by impulse noise. Using a proposedarchitecture that includes an impulse detector and the median filter,the effective methods can be designed. Thus, the image points areclassified into two classes such as a class of noise free samples and aclass of noised image points. In the case of impulse detection theestimate is performed by a median filter whereas a noise free sample ispassed on the output without the change i.e. system works as anidentity filter.

  4. Functional impulsivity and reinforcement sensitivity theory.

    Science.gov (United States)

    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. PMID:16451226

  5. Heroin and amphetamine users display opposite relationships between trait and neurobehavioral dimensions of impulsivity.

    Science.gov (United States)

    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. PMID:24342174

  6. Impulsivity Parameter for Solar Flares

    Science.gov (United States)

    Fajardo-Mendieta, W. G.; Martínez-Oliveros, J. C.; Alvarado-Gómez, J. D.; Calvo-Mozo, B.

    2016-02-01

    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.

  7. IMPULSE---an advanced, high performance nuclear thermal propulsion system

    International Nuclear Information System (INIS)

    IMPULSE is an advanced nuclear propulsion engine for future space missions based on a novel conical fuel. Fuel assemblies are formed by stacking a series of truncated (U, Zr)C cones with non-fueled lips. Hydrogen flows radially inward between the cones to a central plenum connected to a high performance bell nozzle. The reference IMPULSE engine rated at 75,000 lb thrust and 1800 MWt weighs 1360 kg and is 3.65 meters in height and 81 cm in diameter. Specific impulse is estimated to be 1000 for a 15 minute life at full power. If longer life times are required, the operating temperature can be reduced with a concomitant decrease in specific impulse. Advantages of this concept include: well defined coolant paths without outlet flow restrictions; redundant orificing; very low thermal gradients and hence, thermal stresses, across the fuel elements; and reduced thermal stresses because of the truncated conical shape of the fuel elements

  8. Alexithymia, emotion dysregulation, impulsivity and aggression: A multiple mediation model.

    Science.gov (United States)

    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. PMID:26803364

  9. Self-focusing and cross-focusing of Gaussian electromagnetic beams in fully ionized collisional magnetoplasmas

    International Nuclear Information System (INIS)

    This paper presents an analysis and subsequent discussion of the phenomena of self-focusing of single electromagnetic Gaussian beams and cross-focusing of multiple coaxial beams in fully ionized magnetoplasma, taking into account the Ohmic heating of the electrons by the beams and loss of energy by electrons due to collision with the ions and electronic thermal conduction; the energy gained by ions in collision with the electrons has been equated to the energy lost on account of ionic thermal conduction. It is seen that the inclusion of the ionic thermal conduction reduces self/cross-focusing for high values of the magnetic field (?ec) and enhances the same for low values of the magnetic field (?e>>?c); here ?e is the electron collision frequency and ?c,?c are the cyclotron frequencies of electrons and ions, respectively. The wave frequency is assumed to be much higher than the cyclotron frequency of the electrons. The results lead to the conclusion that considerable error occurs by neglecting ionic thermal conduction in a collisional plasma

  10. Dust acoustic solitary and shock excitations in a Thomas-Fermi magnetoplasma

    International Nuclear Information System (INIS)

    The linear and nonlinear properties of dust-acoustic waves are investigated in a collisionless Thomas-Fermi magnetoplasma, whose constituents are electrons, ions, and negatively charged dust particles. At dust time scale, the electron and ion number densities follow the Thomas-Fermi distribution, whereas the dust component is described by the classical fluid equations. A linear dispersion relation is analyzed to show that the wave frequencies associated with the upper and lower modes are enhanced with the variation of dust concentration. The effect of the latter is seen more strongly on the upper mode as compared to the lower mode. For nonlinear analysis, we obtain magnetized Korteweg-de Vries (KdV) and Zakharov-Kuznetsov (ZK) equations involving the dust-acoustic solitary waves in the framework of reductive perturbation technique. Furthermore, the shock wave excitations are also studied by allowing dissipation effects in the model, leading to the Korteweg-de Vries-Burgers (KdVB) and ZKB equations. The analysis reveals that the dust-acoustic solitary and shock excitations in a Thomas-Fermi plasma are strongly influenced by the plasma parameters, e.g., dust concentration, dust temperature, obliqueness, magnetic field strength, and dust fluid viscosity. The present results should be important for understanding the solitary and shock excitations in the environments of white dwarfs or supernova, where dust particles can exist

  11. Electrostatic probe measurements of low-density medium-pressure magneto-plasmas

    International Nuclear Information System (INIS)

    The influence of secondary electron emission from a probe surface on the probe diagnostics are studied in a medium-pressure (p >= 0.1 Torr) low-density (Nsub(e) 10 cm-3) plasma with a weak magnetic field (B <= 1 kG). Both electron and ion saturation currents (Isub(es) and Isub(is)) are used to obtain Nsub(e), and the results are compared with microwave measurements. The increase of Isub(i) due to electron emission occurs; this prevents the accurate determination of Nsub(e) in the same manner as that reported in a plasma without a magnetic field. Even though the uncertainty in determining Nsub(e) due to the effect of emission decreases with increasing B, Isub(is) is not always suitable for Nsub(e) determination. On the other hand, Nsub(e) determined from Isub(es) corrected for magnetic field effects agrees with microwave measurements within 50%. The continuum Laplace limit probe theory of Chang and Laframboise is modified for magneto-plasmas. This theory predicts that a probe in the presence of a magnetic field will be much more sensitive to departures from collisionless conditions than in the absence of a field. Theory and experiments agree satisfactorily. Plasma parameter diagnostic applications are developed in detail. (author)

  12. Stability analysis of self-gravitational electrostatic drift waves for a streaming nonuniform quantum dusty magnetoplasma

    Science.gov (United States)

    Bashir, M. F.; Jamil, M.; Murtaza, G.; Salimullah, M.; Shah, H. A.

    2012-04-01

    Using the quantum hydrodynamic model of plasmas, the stability analysis of self-gravitational electrostatic drift waves for a streaming non-uniform quantum dusty magnetoplasma is presented. For two different frequency domains, i.e., Ω0d≪ωquantum velocity vFe' make these oscillations propagate perpendicular to the ambient magnetic field. This oscillatory behavior of self-gravitational drift waves increases with increase in inhomogeneities and quantum effects while it decreases with increase in the gravitational potential. However, only for the unmagnetized case, the drift waves may become unstable under appropriate conditions giving rise to Jeans instability. The modified threshold condition is also determined for instability by using the intersection method for solving the cubic equation. We note that the inhomogeneity in magnetic field (equilibrium density) through streaming velocity (diamagnetic drift velocity) suppress the Jeans instability depending upon the characteristic scale length of these inhomogeneities. On the other hand, the dust-lower-hybrid wave and the quantum mechanical effects of electrons tend to reduce the growth rate as expected. A number of special cases are also discussed.

  13. Electric field variability and classifications of Titan's magnetoplasma environment

    Directory of Open Access Journals (Sweden)

    C. S. Arridge

    2011-07-01

    Full Text Available The atmosphere of Saturn's largest moon Titan is driven by photochemistry, charged particle precipitation from Saturn's upstream magnetosphere, and presumably by the diffusion of the magnetospheric field into the outer ionosphere, amongst other processes. Ion pickup, controlled by the upstream convection electric field, plays a role in the loss of this atmosphere. The interaction of Titan with Saturn's magnetosphere results in the formation of a flow-induced magnetosphere. The upstream magnetoplasma environment of Titan is a complex and highly variable system and significant quasi-periodic modulations of the plasma in this region of Saturn's magnetosphere have been reported. In this paper we quantitatively investigate the effect of these quasi-periodic modulations on the convection electric field at Titan. We show that the electric field can be significantly perturbed away from the nominal radial orientation inferred from Voyager 1 observations, and demonstrate that upstream categorisation schemes must be used with care when undertaking quantitative studies of Titan's magnetospheric interaction, particularly where assumptions regarding the orientation of the convection electric field are made.

  14. Diffusion and transport phenomena in a collisional magnetoplasma having both streaming and temperature anisotropy: Collisional kinetics

    Indian Academy of Sciences (India)

    J N Mohanty; K C Baral; G Nath

    2007-03-01

    Boltzmann-transport equation is analytically solved for two-component magnetoplasma using Chapman-Enskog analysis to include collisional diffusion transport having anisotropies in both streaming velocity and temperature components. The modified collisional integrals are analytically solved with flux integrals and perturbed kinetic equation to arrive at drift diffusion velocity and resulting transport coefficients which are markedly affected by both streaming and temperature anisotropy. The early isotropic results are recovered in the limit $V_{0} = 0$ and $T_{\\|} = T_{\\bot}$ which reduce to eqs (11.30) and (11.31) of [1] and eqs (2.7) and (2.13) of [2]. The electrical resistivity (n_{\\bot}) diminishes sharply in fusion temperature limit $kT_{\\bot} = 1$ keV. The shape of the curves for both electrical resistivity and thermal conductivity is rectangular hyperbolic. However, for low thermal ratio $(T_{\\|}/T_{\\bot} < 1)$, the curves are raised up and for high thermal ratio $(T_{\\|}/T_{\\bot} > 1)$, they are lowered down the isotropic case $(T_{\\|}/T_{\\bot} > 1)$, showing comparatively diminished magnitudes of the quantities.

  15. Determination of carrier mobility and density in semiconductors by the contactless magnetoplasma methods

    International Nuclear Information System (INIS)

    Considered are new contactless electromagnetic magnetoplasma methods for investigating conductivity parameters in semiconductors in the region of classically weak (BB approximately 1) magnetic fields. A semiconductor is placed into a constant magnetic field but, unlike the Hall measurements where determined are electric field components in a semiconductor with current, measurements according to the new methods include the contactless determination of the components of a variable magnetic field excited in the semiconductor. The case of an isotropic semiconductor was considered. It is shown that the new methods permit to determine the Hall mobility and charge carrier concentration in the region of weak magnetic fields. In the region of intermediate fields the factor ?1, included as a multiplier in expressions for experimentally measured nondiagonal component of conductivity tensor, has a simpler dependence on the magnetic field as compared with the Hall factor. This permit to determine drift mobility and exact concentration. Experimental measurements of electron mobility and density in InSb and Ge are given

  16. Impulsivity, gender, and the platelet serotonin transporter in healthy subjects

    Directory of Open Access Journals (Sweden)

    Donatella Marazziti

    2009-12-01

    Full Text Available Donatella Marazziti, Stefano Baroni, Irene Masala, Francesca Golia, Giorgio Consoli, Gabriele Massimetti, Michela Picchetti, Mario Catena Dell’Osso, Gino Giannaccini, Laura Betti, Antonio Lucacchini, Antonio CiapparelliDipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, University of Pisa, Pisa, ItalyAbstract: The present study explored the possible relationships between impulsivity, gender, and a peripheral serotonergic marker, the platelet serotonin (5-HT transporter (SERT, in a group of 32 healthy subjects. The impulsivity was measured by means of the Barratt Impulsivity Scale, version 11 (BIS-11, a widely used self-report questionnaire, and the platelet SERT was evaluated by means of the specific binding of 3H-paroxetine (3H-Par to platelet membranes, according to standardized protocols. The results showed that women had a higher BIS-11 total score than men, and also higher scores of two factors of the same scale: the motor impulsivity and the cognitive complexity. The analysis of the correlations revealed that the density of the SERT proteins, as measured by the maximum binding capacity (Bmax of 3H-Par, was significantly and positively related to the cognitive complexity factor, but only in men. Men showed also a significant and negative correlation with the dissociation constant, Kd, of (3H-Par binding, and the motor impulsivity factor. These findings suggest that women are generally more impulsive than men, but that the 5-HT system is more involved in the impulsivity of men than in that of women.Keywords: impulsivity, gender, serotonin transporter, Barratt Impulsivity Scale, platelets, 3H-paroxetine

  17. Impulsivity and rapid decision-making for reward

    Directory of Open Access Journals (Sweden)

    StephanieBurnett Heyes

    2012-05-01

    Full Text Available Impulsivity is a feature of many brain disorders. Although often defined as the predisposition to act with an inadequate degree of deliberation, forethought or control, it has proven difficult to measure. This may in part be because, increasingly, impulsivity is recognized as a multifaceted construct, with impulsive decisions potentially arising due to a number of underlying mechanisms. Indeed, in certain contexts, a ‘functional’ degree of impulsivity may promote effective, motivated behavior in healthy participants. Although many tasks have been developed to study impulsivity, few examine decisions made rapidly, for time-sensitive rewards: In this context, a degree of impulsivity may be adaptive. In the current study we examine behavior in 59 adults on a manual ‘Traffic Light’ task which requires participants to take risks under time pressure, if they are to maximize reward. We show that behavioral variables that index rapid anticipatory responding in this paradigm are correlated with a specific self-report measure of impulsivity: ‘lack of premeditation’ on the UPPS Impulsive Behavior Scale. Participants who scored more highly on this subscale performed better on the task. Moreover, anticipatory behavior reduced significantly with age (18-79 years, an effect that continued to be upheld after correction for potential age differences in the ability to judge the timing of responses. Based on these findings, we argue that the Traffic Light task provides a parametric method to study a ‘functional’ aspect of impulsivity in health and disease: namely, rapid decision-making in pursuit of risky, time-sensitive rewards.

  18. Temperament and Impulsivity Predictors of Smoking Cessation Outcomes

    Science.gov (United States)

    López-Torrecillas, Francisca; Perales, José C.; Nieto-Ruiz, Ana; Verdejo-García, Antonio

    2014-01-01

    Aims Temperament and impulsivity are powerful predictors of addiction treatment outcomes. However, a comprehensive assessment of these features has not been examined in relation to smoking cessation outcomes. Methods Naturalistic prospective study. Treatment-seeking smokers (n = 140) were recruited as they engaged in an occupational health clinic providing smoking cessation treatment between 2009 and 2013. Participants were assessed at baseline with measures of temperament (Temperament and Character Inventory), trait impulsivity (Barratt Impulsivity Scale), and cognitive impulsivity (Go/No Go, Delay Discounting and Iowa Gambling Task). The outcome measure was treatment status, coded as “dropout” versus “relapse” versus “abstinence” at 3, 6, and 12 months endpoints. Participants were telephonically contacted and reminded of follow-up face to face assessments at each endpoint. The participants that failed to answer the phone calls or self-reported discontinuation of treatment and failed to attend the upcoming follow-up session were coded as dropouts. The participants that self-reported continuing treatment, and successfully attended the upcoming follow-up session were coded as either “relapse” or “abstinence”, based on the results of smoking behavior self-reports cross-validated with co-oximetry hemoglobin levels. Multinomial regression models were conducted to test whether temperament and impulsivity measures predicted dropout and relapse relative to abstinence outcomes. Results Higher scores on temperament dimensions of novelty seeking and reward dependence predicted poorer retention across endpoints, whereas only higher scores on persistence predicted greater relapse. Higher scores on the trait dimension of non-planning impulsivity but not performance on cognitive impulsivity predicted poorer retention. Higher non-planning impulsivity and poorer performance in the Iowa Gambling Task predicted greater relapse at 3 and 6 months and 6 months respectively. Conclusion Temperament measures, and specifically novelty seeking and reward dependence, predict smoking cessation treatment retention, whereas persistence, non-planning impulsivity and poor decision-making predict smoking relapse. PMID:25474540

  19. Impulse Generation Mechanism in Glycerin Propellant Laser Thruster

    International Nuclear Information System (INIS)

    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 μm wavelength was focused in a 2-mm diameter glycerin droplet in vacuum condition (∼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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. The Neurobiology of Impulsive Aggression.

    Science.gov (United States)

    Blair, Robert J R

    2016-02-01

    This selective review provides a model of the neurobiology of impulsive aggression from a cognitive neuroscience perspective. It is argued that prototypical cases of impulsive aggression, those associated with anger, involve the recruitment of the acute threat response system structures; that is, the amygdala, hypothalamus, and periaqueductal gray. It is argued that whether the recruitment of these structures results in impulsive aggression or not reflects the functional roles of ventromedial frontal cortex and dorsomedial frontal and anterior insula cortex in response selection. It is also argued that impulsive aggression may occur because of impaired decision making. The aggression may not be accompanied by anger, but it will reflect disrupted evaluation of the rewards/benefits of the action. PMID:26465707

  2. Resonant Impulsive Stimulated Raman Scattering

    International Nuclear Information System (INIS)

    Using a femtosecond dye laser, we observe in real-time vibrational oscillations excited by impulsive stimulated Raman scattering (ISRS) close to an electronic resonance. We perform single-beam Raman excitation and probe the driven coherence by a polarization-sensitive detection. We demonstrate for the first time impulsively Raman-induced dichroism, birefringence as well as frequency and time delay shifts. We analyse the characteristics of resonant ISRS on a vibrational mode of a dye molecule (malachite green) in solution

  3. Impulsivity, risk taking, and timing.

    Science.gov (United States)

    Baumann, Ana A; Odum, Amy L

    2012-07-01

    This study examined the relations among measures of impulsivity and timing. Impulsivity was assessed using delay and probability discounting, and self-report impulsivity (as measured by the Barratt Impulsiveness Scale; BIS-11). Timing was assessed using temporal perception as measured on a temporal bisection task and time perspective (as measured by the Zimbardo Time Perspective Inventory). One hundred and forty three college students completed these measures in a computer laboratory. The degree of delay discounting was positively correlated with the mean and range of the temporal bisection procedure. The degree of delay and probability discounting were also positively correlated. Self-reported motor impulsiveness on the BIS-11 was positively correlated with present hedonism and negatively correlated with future orientation on the ZTPI. Self-reported non-planning on the BIS-11 was positively correlated with fatalism on the ZTPI. These results show that people who overestimate the passage of time (perceive time as passing more quickly) hold less value in delayed rewards. They also confirm previous results regarding the relation between delay and probability discounting, as well as highlight similarities in self-report measures of impulsivity and time perspective. PMID:22542458

  4. Impulsivity, Risk Taking, and Timing

    Science.gov (United States)

    Baumann, Ana A.; Odum, Amy. L.

    2012-01-01

    This study examined the relations among measures of impulsivity and timing. Impulsivity was assessed using delay and probability discounting, and self-report impulsivity (as measured by the Barratt Impulsiveness Scale; BIS-11). Timing was assessed using temporal perception as measured on a temporal bisection task and time perspective (as measured by the Zimbardo Time Perspective Inventory). One hundred and forty three college students completed these measures in a computer laboratory. The degree of delay discounting was positively correlated with the mean and range of the temporal bisection procedure. The degree of delay and probability discounting were also positively correlated. Self-reported Motor impulsiveness on the BIS-11 was positively correlated with Present Hedonism and negatively correlated with Future orientation on the ZTPI. Self-reported Non-Planning on the BIS-11 was positively correlated with Fatalism on the ZTPI. These results show that people who overestimate the passage of time (perceive time as passing more quickly) hold less value in delayed rewards. They also confirm previous results regarding the relation between delay and probability discounting, as well as highlight similarities in self-report measures of impulsivity and time perspective. PMID:22542458

  5. Cross-Field Electron Heat Transport in a Magnetoplasma, in the Presence of Ion Turbulence

    Science.gov (United States)

    Needelman, David Dore

    Cross-field heat transport through a cylindrical pulsed argon afterglow magnetoplasma, (B_0 = 48-300G, rm T_{e} ~ 0.5-7 eV, n_{e} ~ 10^{11} cm^{ -3}, Phi_{s } ~ 2V, radius = 5 cm), is investigated. The study of heat flow is relevant to the fields of fusion engineering and space physics. A BaO-coated dispenser cathode is used to produce a pulsed electron beam, (V_{b}=750 V, I_{b} = 1A, radius = 1.27 cm, tau_{b} = 5 - 10mus, fired 300 mus into the afterglow), propagating down the central axis of the plasma. The beam heats the background electrons within some centimeters of the beam launching point (Whe85); heat diffuses along field lines, forming a "flux tube" of hot plasma. Biased grids, (radius = 5 cm, V_{g} = -200V), are used to retard the axial heat flow through the tube. A radially inserted Langmuir probe is used to map T_{e}, n_ {e}, and Phi_{s } as a function of position and time. There profiles are used to deduce the electron cross-field thermal conductivity coefficient, kappa_| . Anomalous heat transport is found for all cases studied; kappa_| is found to be up to two orders of magnitude above classical predictions. Such transport is attributed to quasilinear effects; collisions of the background electrons with radial ion acoustic waves created indirectly by the beam, through action of the beam/plasma and oscillating two-stream instabilities (Whe85), and with azimuthal ion acoustic waves, created by the pressure-gradient instability(All74). An enhanced collision frequency leads to faster cross-field particle and heat diffusion. Measurements of wave amplitudes are presented, as are correlation measurements proving the waves are ion acoustic. Comparisons of experimental measurements with quasilinear theory predictions (Man78) are shown to be quite close.

  6. Self-organization of local magnetoplasma structures in the upper layers of the solar convection zone

    International Nuclear Information System (INIS)

    Self-organization and evolution of magnetoplasma structures in the upper layers of the solar convection zone are discussed as a process of diffuse aggregation of magnetic flux tubes. Equations describing the tube motion under the action of magnetic interaction forces, hydrodynamic forces, and random forces are written explicitly. The process of aggregation of magnetic flux tubes into magnetic flux clusters of different shapes and dimensions is simulated numerically. The obtained structures are compared with the observed morphological types of sunspot groups. The quantitative comparison with the observational data was performed by comparing the fractal dimensions of the photospheric magnetic structures observed in solar active regions with those of structures obtained in the numerical experiment. The model has the following free parameters: the numbers of magnetic flux tubes with opposite polarities on the considered area element (Nn and Ns), the average radius of the cross section of the magnetic flux tube (a), its effective length (l), the twist factor of the tube field (k), and the absolute value of the average velocity of chaotic tube displacements (d). Variations in these parameters in physically reasonable limits leads to the formation of structures (tube clusters of different morphological types) having different fractal dimensions. Using the NOAA 10488 active region, which appeared and developed into a complicated configuration near the central meridian, as an example, it is shown that good quantitative agreement between the fractal dimensions is achieved at the following parameters of the model: Nn = Ns = 250 ± 50; a = 150 ± 50 km; l ∼ 5000 km, and d = 80 ± 10 m/s. These results do not contradict the observational data and theoretical estimates obtained in the framework of the Parker “spaghetti” model and provide new information on the physical processes resulting in the origin and evolution of local magnetic plasma structures in the near-photospheric layers of the solar convection zone

  7. Non-linear diffusion of charged particles in a turbulent magnetoplasma

    International Nuclear Information System (INIS)

    A unified theory is presented which describes non-linear effects on relative and absolute diffusion of charged particles in a magnetoplasma, in analogy with analogous methods used for diffusion studies of pollutants in the environment. Explicit results are obtained for non-linear diffusion of test particles represented by their guiding centers in a turbulent energy spectrum in K-1 and K-3, which corresponds to recent measurements in the T.F.R. Tokamak. As expected, a BOHM scaling of the absolute diffusion coefficient is obtained for frozen turbulence. The growth of an initially small cloud of particles in an arbitrary turbulent medium corresponds to the process of relative diffusion. It is described by a generalization of the Brownian motion, including a first stage of very slow initial relative diffusion, followed by a stage of rapid expansion of the cloud up to the final stage in which particles become uncorrelated, and Brownian diffusion is reached asymptotically. The stage of exponential growth, observed in fluid turbulence corresponds to the clump effect in plasma turbulence. It is entirely due to the effect of trajectory correlations. The LJAPUNOV exponent of this exponential separation is obtained analytically. Numerical solutions of the diffusion equation are presented for the effective radius of the cloud as function of time in the case of a model spectrum of drift-wave turbulence. When compared with classical Brownian diffusion of uncorrelated particles, the effective ''diffusion coefficient'' for correlated particles is found to be reduced by orders of magnitude for rather long times. Practical implications for experimental situations are also discussed (Barium clouds released in the ionosphere, pellet injection in e.g. Tokamaks)

  8. Impulsivity and sensation seeking in alcohol abusing patients with schizophrenia

    Directory of Open Access Journals (Sweden)

    AlainDervaux

    2010-09-01

    Full Text Available Objective: Some studies have found that high levels of impulsivity and sensation seeking, particularly disinhibition are associated with substance abuse in patients with schizophrenia, as in the general population. However, no study has assessed impulsivity and sensation seeking specifically in schizophrenia patients with alcohol abuse or dependence. Material and Methods: We compared impulsivity and sensation seeking in a group of schizophrenia patients (DSM-III-R criteria with lifetime alcohol abuse or dependence (n=34 and in a group without lifetime substance abuse or dependence (n=66. The patients were assessed using the Composite International Diagnostic Interview (CIDI for DSM-III-R disorders, the Positive and Negative Syndrome Scale, the Barratt Impulsivity Scale (BIS, the Zuckerman Seeking Sensation Scale (SSS, and the Physical Anhedonia Scale (PAS. Results: The mean scores for impulsivity and sensation seeking were higher in the group with lifetime alcohol abuse or dependence than in the group without substance abuse or dependence (BIS: 63.4 SD: 18,7 vs 51.3 SD: 14.2 respectively, ANOVA: F=11.12, p=0.001; SSS: 17.6 SD: 5.9 vs 13.5 SD: 6.7 respectively, ANOVA: F=7.45, p=0.008. There was no significant differences between the two groups on PAS score. Conclusion: Increased impulsivity or sensation seeking may be a link between schizophrenia and alcohol abuse or dependence.

  9. Dense Z-pinch plasma as a dynamical percolating network: from laboratory plasmas to a magnetoplasma universe.

    Science.gov (United States)

    Kukushkin, A. B.; Rantsev-Kartinov, V. A.

    The results of a high-resolution processing, based on techniques of fractal dimension analysis, of experimental data from earlier experiments on the linear Z-pinches are presented, which prove the electric current-carrying plasmas to be a random fractal medium. The basic building block of this medium is identified to be an almost-closed helical filamentary magnetoplasma configuration (called heteromac). The heteromacs are coupled together through long-range self-sustained filamentation and, thus, form a dynamical percolating network with dissipation. The results (i) extend recently identified phenomenon of the 3D large-scale (up to several centimeter size) helical filamentary plasma structures (Kukushkin et al. 1994, 1995, 1997) in plasma focus gaseous discharges to the case of Z-pinch gaseous discharges and (ii) provide a novel view into the dynamics of Z-pinch's necks, plasma spikes, and magnetic bubbles as well as into generic features of electric current-carrying plasmas varying from low-electric current laboratory plasmas to cosmic plasmas. This covers about 30 orders of magnitude of length scale and suggests unprecedented opportunities for interpolating between and extrapolating from well-understood phenomena. A magnetoplasma universe model is suggested.

  10. Impulsivity Parameter for Solar Flares

    CERN Document Server

    Fajardo-Mendieta, W G; Alvarado-Gómez, J D; Calvo-Mozo, B

    2016-01-01

    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...

  11. Impulse control disorders and depression.

    Science.gov (United States)

    Lejoyeux, Michel; Arbaretaz, Marie; McLoughlin, Mary; Ads, Jean

    2002-05-01

    This study assessed the frequency of impulse control disorders (ICDs) and their association with bulimia, compulsive buying, and suicide attempts in a population of depressed inpatients. We investigated ICDs using the Minnesota Impulsive Disorders Interview. Patients answered the Zuckerman Sensation-Seeking Scale and the Barratt Impulsivity Rating Scale. Among the 31 depressed patients who met criteria for ICD (ICD+ group), we found 18 cases of intermittent explosive disorder, three cases of pathological gambling, four cases of kleptomania, three cases of pyromania, and three cases of trichotillomania. Patients with co-occurring ICDs were significantly younger (mean age = 37.7 versus 42.8 years). Patients with kleptomania had a higher number of previous depressive episodes (5.7 versus 1.3), and patients with pyromania had a higher number of previous depressions (3.3 versus 1.3, p =.01). Bipolar disorders were more frequent in the ICD+ group than in the ICD- group (19% versus 1.3%, p =.002), whereas antisocial personality was not (3% versus 1%, p = ns). Bulimia (42% versus 10.5%, p =.005) and compulsive buying (51% versus 22%, p =.006) were significantly more frequent in the ICD+ group. Patients from the ICD+ group had higher scores of motor impulsivity assessed with the Barratt Impulsivity rating scale (p =.01). PMID:12011611

  12. Modifying the risk associated with an impulsive temperament: a prospective study of drug dependence treatment.

    Science.gov (United States)

    Staiger, Petra K; Dawe, Sharon; Richardson, Ben; Hall, Kate; Kambouropoulos, Nicolas

    2014-11-01

    The evidence linking the personality trait of impulsivity and substance misuse is well established. Importantly, impulsivity not only predicts substance misuse problems but has an association with duration in treatment, likelihood of completing treatment and time to relapse. Treatment that focuses on increasing awareness and acceptance of thoughts and emotions may potentially address impulsive behaviour and in this respect improve treatment outcomes for substance misuse. The current paper investigated the relationship between the facet of impulsivity that taps into poor inhibitory control and treatment outcome. In addition, there was a specific focus on ascertaining the impact of an increase in awareness and attentional control measured in 144 adult substance users receiving treatment in a residential therapeutic community. Impulsivity predicted poorer treatment outcome (measured as drug use severity). Increases in awareness and acceptance of emotions and thoughts during treatment were related to better outcome although this was not associated with baseline levels of impulsivity. Clinical and theoretical implications are discussed. PMID:24924874

  13. Recreational drug use and impulsivity in a population of canadian undergraduate drinkers.

    Science.gov (United States)

    Balodis, Iris M; Potenza, Marc N; Olmstead, Mary C

    2010-01-01

    The consumption of drugs during young adulthood may be particularly detrimental given important neurodevelopmental changes occurring during this period. As impulsivity may lead to substance use and substance use to the commission of seemingly impulsive acts, an improved understanding of the relationship between alcohol use, other substance use and impulsivity in young adults is important. We gathered information on self-reported impulsivity, recreational drug use, and drinking habits of 205 (105 female) undergraduate students. Results showed that 64% of the students reported using marijuana at least once and these individuals were more likely to report binge drinking. Polysubstance use, defined as using marijuana and at least one other illicit substance, was reported by 20% of students. These individuals reported more drinking occasions per month and had higher levels of trait impulsivity. Rates of recreational drug use were similar to those reported in recent national surveys, suggesting an increase in experimentation with specific illicit drugs. Given that a majority of undergraduate drinkers reported marijuana use and its association with binge drinking, future research should clarify the relationship between marijuana use and binge consumption of alcohol and prevention efforts should consider the conjoint targeting of marijuana and binge drinking. The associations between polysubstance use, binge-level alcohol consumption and elevated self-reported impulsivity suggests that perceived trait impulsivity across multiple domains may predispose to excessive use of multiple substances. Longitudinal studies should examine the contribution of impulsivity to the initiation and experimentation with illicit drugs and the influence of specific substances on impulsivity. PMID:21423440

  14. Impulsive control of time-delay systems using delayed impulse and its application to impulsive master-slave synchronization

    International Nuclear Information System (INIS)

    This Letter is concerned with impulsive control of a class of nonlinear time-delay systems. Some uniform stability criteria for the closed-loop time-delay system under delayed impulsive control are derived by using piecewise Lyapunov functions. Then the criteria are applied to impulsive master-slave synchronization of some secure communication systems with transmission delays and sample delays under delayed impulsive control. Two numerical examples are given to illustrate the effectiveness of the derived results

  15. Impulse formalism for atom-molecule collisions: Inadequacy of the peaking approximation

    International Nuclear Information System (INIS)

    Expressions for differential and total cross sections for atom-diatom scattering are derived using the impulse formalism without any approximations. Results for the rotational-vibrational scattering are obtained without using the peaking approximation (PA). For the specific case of a hard-core potential, it is shown that, except for elastic scattering, PA results are substantially different from the true impulse results

  16. Impulse-Excited Energy Harvester based on Potassium-Ion- Electret

    Science.gov (United States)

    Ashizawa, H.; Mitsuya, H.; Ishibashi, K.; Ishikawa, T.; Fujita, H.; Hashiguchi, G.; Toshiyoshi, H.

    2015-12-01

    We have developed an energy harvester that is specifically desired for impulse acceleration of infrastructure vibrations such as sudden motion at railway bridges. The energy harvester based on potassium-ion-electret on the sidewalls of 1.8- ?m-gap comb electrodes generated a 64 ?Ap-p current during low impulse acceleration, which was large enough to light a green LED.

  17. Neuroanatomical and Neurochemical Basis of Impulsivity

    Directory of Open Access Journals (Sweden)

    Kemal Yazici

    2010-08-01

    Full Text Available The term ‘impulsivity’ encompasses a multitude of behaviours that are poorly conceived, premature, inappropriate, and that frequently result in unwanted or deleterious outcomes. Impulsivity manifests as impatience carelessness, risk-taking, sensation-seeking and pleasure-seeking, an underestimated sense of harm, and extroversion. Impulsivity is a core symptom of a broad spectrum of psychiatric disorders. Through focusing on different aspects of impulsive behavior, it has proved possible to devise a variety of behavioral paradigms to measure impulsivity in both human and non-human subjects. These can be broadly divided into two categories: those measuring impulsive action or motoric impulsivity, and those measuring impulsive choice or impulsive decision-making. Impulsive action can be broadly defined as the inability to withhold from making a response. Within the framework of behavioral neuroscience and cognitive psychology, impulse control has been described as an active inhibitory mechanism which modulates the internally or externally driven pre-potent desire for primary reinforcers such as food, sex or other highly desirable rewards. This inhibitory control mechanism may provide the substrate by which rapid conditioned responses and reflexes are transiently suppressed, so that slower cognitive mechanisms can guide behavior. This process is referred to as response inhibition. Two of the most common tests used to study inhibitory processes are the go/no-go and stop-signal reaction time tasks. Impulsivity is also evident in the making of impulsive decisions or choices as well as in impulsive actions. Here, there is no “pre-potent” response that is primed and then forcibly inhibited, but a decision-making processes. Impulsive decision making or impulsive choice is defined as initiating actions without adequately considering other possible choices or consequences. Impulsive choice is typically measured in the delay discounting paradigm. In tis paradigm, the tendency to prefer small immediate rewards over larger, more delayed reinforcers is measured. İmpulsive choice is defined by a greater tendency to value or choose smaller, more immediate reinforcers. Impulsivity is a multi-faceted behaviour. This behaviour may be studied by subdividing it into different processes neuroanatomically and neurochemically. Neuroanatomical data support the suggestion that behavioral disinhibition (impulsive action / motoric impulsivity and delay-discounting (impulsive choice / decision making differ in the degree to which various components of frontostriatal loops are implicated in their regulation. The dorsal prefrontal cortex does not appear to be involved in mediating impulsive choice, yet does have some role in regulating inhibitory processes. In contrast, there appears to be a pronounced role for the orbitofrontal cortex and basolateral amygdala in controlling impulsive choice. Other structures, however, such as the nucleus accumbens and subthalamic nucleus may be common to both circuits. From the neurochemical perspective, dopamine system and dopamine- 2 (D2 receptors in particular, seems to be closely involved in making impulsive choice. When the noradrenaline system does not function optimally, it might contribute to increased impulsivity. Serotonin might act upon prefrontal cortex to decrease impulsive choices. Interactions between the serotonin and the dopamine systems are important in the regulation of impulsive behaviour. It is possible that various receptor subtypes of the serotonin system may exert differing and even contrasting effects on impulsive behaviour. Although it is very informative to study neurotransmitter systems separately, it should be kept in mind that there are very intimate interactions between the neurotransmitter systems mentioned above. Based on the fact that impulsivity is regulated through multiple neurotransmitters and even more receptors, one may suggest that pharmacotherapy of impulsivity requires a drug acting on more than one receptor. In addition, when considering improving impulsivity for the treatment of a psychiatric disorder, it is always necessary to know which type of impulsive behaviour exists in that particular disorder. Hence, improving impulsivity for the treatment of psychiatric disorders requires tailoring of pharmacological agents in a precise and perhaps in an individualized manner.

  18. Commentary on Hyperkinetic Impulse Disorder

    Science.gov (United States)

    Barkley, Russell A.

    2011-01-01

    Dr. Goldstein continues the laudable practice of reprinting articles of historical significance in the history of ADHD with this selective reprinting of material from the original article by Maurice Laufer, Eric Denhoff, and Gerald Solomons on hyperkinetic impulsive disorder (HID) in children. This article on HID is among the first articles to…

  19. Female impulsive aggression: a sleep research perspective.

    Science.gov (United States)

    Lindberg, Nina; Tani, Pekka; Putkonen, Hanna; Sailas, Eila; Takala, Pirjo; Eronen, Markku; Virkkunen, Matti

    2009-01-01

    The rate of violent crimes among girls and women appears to be increasing. One in every five female prisoners has been reported to have antisocial personality disorder. However, it has been quite unclear whether the impulsive, aggressive behaviour among women is affected by the same biological mechanisms as among men. Psychiatric sleep research has attempted to identify diagnostically sensitive and specific sleep patterns associated with particular disorders. Most psychiatric disorders are typically characterized by a severe sleep disturbance associated with decreased amounts of slow wave sleep (SWS), the physiologically significant, refreshing part of sleep. Among men with antisocial behaviour with severe aggression, on the contrary, increased SWS has been reported, reflecting either specific brain pathology or a delay in the normal development of human sleep patterns. In our preliminary study among medication-free, detoxified female homicidal offenders with antisocial personality disorder, the same profound abnormality in sleep architecture was found. From the perspective of sleep research, the biological correlates of severe impulsive aggression seem to share similar features in both sexes. PMID:19095304

  20. Impulse sales cooler. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, Per Henrik (DTI, Taastrup (Denmark))

    2010-11-15

    In the past years, the use of impulse coolers has increased considerably and it is estimated that at least 30.000 are installed in shops in Denmark. In addition, there are many small barrel-shaped can coolers. Most impulse coolers are open, which results in a large consumption of energy, and the refrigeration systems are often quite inefficient. A typical impulse cooler uses app. 5 - 8 kWh/day corresponding to a consumption of energy in the magnitude of 60 GWh/year. For several years, the Danish company Vestfrost A/S has produced an impulse sales cooler in the high-efficiency end and the energy consumption of the cooler is measured to be 4.15 kWh/day. The POS72 cooler formed the baseline of this project. At the start-up meeting in 2008, several ideas were discussed with the objective to reduce energy consumption and to use natural refrigerants. Among the ideas were better air curtains, removable lids, better condensers, use of R600a refrigeration system and better insulation. Three generations of prototypes were built and tested in a climate chamber at Danish Technological Institute and the third generation showed very good performance: the energy consumption was measured to 2.215 kWh/day, which is a 47% reduction compared to the baseline. That was achieved by: 1) Improving the cold air cycling system including the air curtain. 2) Using the natural refrigerant R600a (isobutane) and the Danfoss NLE9KTK compressor, which has better efficiency compared to the compressor in the baseline product. 3) Using a box type condenser without fins (preventing dust build-up) and with a relatively high surface area. 4) Improving the insulation value of the plastic cabinet by reducing turbulence in the air gap between the plastic walls and improving the insulation value of the EPS moulded insulation surrounding the refrigeration system at the bottom of the cooler. 5) Preventing short-circuit of warm air around the condenser. 6) The improvements are cost efficient and will not add much to the cost of the cooler. The development project has resulted in a unique impulse sales cooler using natural refrigerant and a refrigeration system, which consumes about half the amount of energy compared to the previous Vestfrost impulse cooler and less than half of the energy compared to other types of impulse sales coolers. (LN)

  1. Online Impulse Buying and Product Involvement

    OpenAIRE

    Tsai Chen

    2008-01-01

    Do consumers behavior different on the Internet from other marketing channels? This study investigates impulse buying behaviors in both traditional store and online shopping contexts. The results show that impulsive buying tendency and involvement with clothing products is positively associated with impulse buying behavior of clothing in traditional store shopping, but not online. For computer peripherals, on the other hand, higher impulsive buying tendency and higher product involvement are ...

  2. Full averaging of fuzzy impulsive differential inclusions

    Directory of Open Access Journals (Sweden)

    Natalia V. Skripnik

    2010-09-01

    Full Text Available In this paper the substantiation of the method of full averaging for fuzzy impulsive differential inclusions is studied. We extend the similar results for impulsive differential inclusions with Hukuhara derivative (Skripnik, 2007, for fuzzy impulsive differential equations (Plotnikov and Skripnik, 2009, and for fuzzy differential inclusions (Skripnik, 2009.

  3. Impulse noise estimation and removal for OFDM systems

    KAUST Repository

    Al-Naffouri, Tareq Y.

    2014-03-01

    Orthogonal Frequency Division Multiplexing (OFDM) is a modulation scheme that is widely used in wired and wireless communication systems. While OFDM is ideally suited to deal with frequency selective channels and AWGN, its performance may be dramatically impacted by the presence of impulse noise. In fact, very strong noise impulses in the time domain might result in the erasure of whole OFDM blocks of symbols at the receiver. Impulse noise can be mitigated by considering it as a sparse signal in time, and using recently developed algorithms for sparse signal reconstruction. We propose an algorithm that utilizes the guard band subcarriers for the impulse noise estimation and cancellation. Instead of relying on ℓ1 minimization as done in some popular general-purpose compressive sensing schemes, the proposed method jointly exploits the specific structure of this problem and the available a priori information for sparse signal recovery. The computational complexity of the proposed algorithm is very competitive with respect to sparse signal reconstruction schemes based on ℓ1 minimization. The proposed method is compared with respect to other state-of-the-art methods in terms of achievable rates for an OFDM system with impulse noise and AWGN. © 2014 IEEE.

  4. Simultaneous excitement of electron and ion resonances in a magnetoplasma by a high frequency electromagnetic field low frequency modulated

    International Nuclear Information System (INIS)

    A single-particle, collisionless, non-relativistic theory is exposed, in which the possibility is shown of exciting electron and ion resonances in a magnetoplasma, by means of a high frequency electromagnetic field, whose amplitude is low frequency modulated. Two solutions of this problem are given in this report. The first one rests on the possibility of exciting the ion cyclotron resonance taking into account the low frequency electromagnetic field low frequency modulated. In the second solution the possibility of exciting the electron and ion resonances is considered in an electromagnetic field, whose magnetic component parallel to vector B0 is low frequency modulated. The results are discussed in the field of a cylindrical wave guide driven in the TE01-mode, vector B0 being parallel to the axis. (Author)

  5. Nonparaxial theory of laser-driven plasma waves phase velocity in partially stripped magneto-plasma channels and wakefield acceleration

    International Nuclear Information System (INIS)

    A nonlinear theory of nonparaxial propagation of ultraintense and ultrashort circularly polarized Gaussian laser pulses through an inhomogeneous partially stripped underdense magneto-plasma channel with a parabolic radial density profile is examined analytically and by one-dimensional particle-in-cell simulations. The direction of magnetic field is considered along the direction of propagation of the pulse. An analytical expression for the wakefield is derived. It is observed that wakefield structures depend on the applied external magnetic field and inhomogeneity of a plasma. Further, equations for the plasma waves phase velocity and the laser pulse group velocity are derived and examined numerically. It is observed that the group velocity of a laser pulse is significantly greater than the plasma waves phase velocity. These velocities depend on the applied magnetic field and the polarization state of the electric field of the laser pulse. (paper)

  6. Effects of inhomogeneity on the Shukla-Nambu-Salimullah and wake potentials in a streaming dusty magnetoplasma

    International Nuclear Information System (INIS)

    Detailed properties of the electrostatic Shukla-Nambu-Salimullah and the dynamical oscillatory wake potentials in an inhomogeneous dusty magnetoplasma in the presence of ion streaming, as in a laboratory discharge plasma, have been examined analytically. The potentials become sensitive functions of the external static magnetic field, the scale-length of inhomogeneity, and the deviation from the linear ion streaming velocity. For a decreasing ion density gradient, there is a limit of existence of the static modified shielding potential. For a strongly inhomogeneous dusty plasma, the effective length of the oscillatory wake potential increases with increasing deviation of the ion streaming velocity (ui0y), but it does not depend on the external magnetic field. (author)

  7. Nonlinear dispersion and transverse profile of intense electromagnetic waves, propagating through electron-positron-ion hot magnetoplasma

    Energy Technology Data Exchange (ETDEWEB)

    Javan, N. Sepehri, E-mail: sepehri-javan@uma.ac.ir; Homami, S. H. H. [Department of physics, University of Mohaghegh Ardabili, PO Box 179, Ardabil (Iran, Islamic Republic of)

    2015-02-15

    Self-guided nonlinear propagation of intense circularly-polarized electromagnetic waves in a hot electron-positron-ion magnetoplasma is studied. Using a relativistic fluid model, a nonlinear equation is derived, which describes the interaction of the electromagnetic wave with the plasma in the quasi-neutral approximation. Transverse Eigen modes, the nonlinear dispersion relation and the group velocity are obtained. Results show that the transverse profile in the case of magnetized plasma with cylindrical symmetry has a radially damping oscillatory form. Effect of applying external magnetic fields, existence of the electron-positron pairs, changing the amplitude of the electromagnetic wave, and its polarization on the nonlinear dispersion relation and Eigen modes are studied.

  8. On Risk-Sensitive Ergodic Impulsive Control of Markov Processes

    International Nuclear Information System (INIS)

    Impulsive control of continuous-time Markov processes with risk- sensitive long-run average cost is considered. The most general impulsive control problem is studied under the restriction that impulses are in dyadic moments only. In a particular case of additive cost for impulses, the impulsive control problem is solved without restrictions on the moments of impulses

  9. Online Impulse Buying and Product Involvement

    Directory of Open Access Journals (Sweden)

    Tsai Chen

    2008-12-01

    Full Text Available Do consumers behavior different on the Internet from other marketing channels? This study investigates impulse buying behaviors in both traditional store and online shopping contexts. The results show that impulsive buying tendency and involvement with clothing products is positively associated with impulse buying behavior of clothing in traditional store shopping, but not online. For computer peripherals, on the other hand, higher impulsive buying tendency and higher product involvement are positively associated with higher impulse buying online, but not in-store shopping.

  10. Laser impulse coupling at 130 fs

    International Nuclear Information System (INIS)

    We measured the momentum coupling coefficient C m and laser-generated ion drift velocity and temperature in the femtosecond (fs) region, over a laser intensity range from ablation threshold to about one hundred times threshold. Targets were several pure metals and three organic compounds. The organic compounds were exothermic polymers specifically developed for the micro-laser plasma thruster, and two of these used 'tuned absorbers' rather than carbon particles for laser absorption. The metals ranged from Li to W in atomic weight. We measured time of flight (TOF) profiles for ions. Specific impulse reached record values for this type of measurement and ablation efficiency was near 100%. These measurements extend the laser pulsewidth three orders of magnitude downward in pulsewidth relative to previous reports. Over this range, we found C m to be essentially constant. Ion velocity ranged from 60 to 180 km/s

  11. Impulsivity, impulsive and reflective processes and the development of alcohol use and misuse in adolescents and young adults

    Directory of Open Access Journals (Sweden)

    ReinoutWiers

    2010-09-01

    Full Text Available This paper contrasts dual-process and personality approaches in the prediction of addictive behaviors and related risk behaviors. In dual-process models, behavior is described as the joint outcome of qualitatively different “impulsive” (or associative and “reflective” processes. There are important individual differences regarding both types of processes, and the relative strength of both in a specific situation is influenced by prior behavior and state variables (e.g., fatigue, alcohol use. From this perspective, a specific behavior (e.g., alcohol misuse can be predicted by the combined indices of the behavior-related impulsive processes (e.g., associations with alcohol, and reflective processes, including the ability to refrain from a motivationally salient action. Personality approaches have reported that general traits such as impulsivity predict addictive behaviors. Here we contrast these two approaches, with supplementary analyses on four datasets. We hypothesized that trait impulsivity can predict specific risky behaviors, but that its predictive power disappears once specific behavior-related associations, indicators of executive functioning, and their interaction are entered into the equation. In all four studies the observed interaction between specific associations and Executive Control (EC was robust: trait impulsivity did not diminish the prediction of alcohol use by the interaction. Trait impulsivity was not always related to alcohol use, and when it was, the predictive power disappeared after entering the interaction between behavior-specific associations and EC in one study, but not in the other. These findings are interpreted in relation to the validity of the measurements used, which leads to a more refined hypothesis.

  12. Neurophysiological markers of multiple facets of impulsivity.

    Science.gov (United States)

    Neal, Lauren B; Gable, Philip A

    2016-03-01

    Human behavior is influenced by three core personality systems: approach, avoidance, and supervisory control. The supervisory control system is inversely related to impulsivity. Although past research has related some aspects of impulsivity to frontal hemispheric asymmetry, impulsivity as a multi-faceted construct has not been studied in relation with frontal asymmetry. In addition, past work has potentially confounded impulsivity with approach-motivation. In the current study, greater relative left frontal activity was related to multiple facets of impulsivity: negative urgency, lack of premeditation, lack of perseverance, and positive urgency. Regressing both positive and negative urgency on frontal asymmetry revealed that approach-related positive urgency related to greater left frontal activity, but withdrawal-related negative urgency marginally related to greater right frontal activity. These results suggest that impulsivity, independent of affective valence, relates to greater left frontal activity. When controlling for trait approach motivation, the relationship between impulsivity and left frontal activity is unchanged. PMID:26808340

  13. Effects of multiple scatter on the propagation and absorption of electromagnetic waves in a field-aligned-striated cold magneto-plasma: implications for ionospheric modification experiments

    OpenAIRE

    Robinson, T. R.

    2002-01-01

    A new theory of the propagation of low power electromagnetic test waves through the upper-hybrid resonance layer in the presence of magnetic field-aligned plasma density striations, which includes the effects of multiple scatter, is presented. The case of sinusoidal striations in a cold magnetoplasma is treated rigorously and then extended, in an approximate manner, to the broad-band striation spectrum and warm plasma cases. In contrast to previous, single scatter theo...

  14. Effects of multiple scatter on the propagation and absorption of electromagnetic waves in a field-aligned-striated cold magneto-plasma: implications for ionospheric modification experiments

    OpenAIRE

    Robinson, T. R.

    2002-01-01

    A new theory of the propagation of low power electromagnetic test waves through the upper-hybrid resonance layer in the presence of magnetic field-aligned plasma density striations, which includes the effects of multiple scatter, is presented. The case of sinusoidal striations in a cold magnetoplasma is treated rigorously and then extended, in an approximate manner, to the broad-band striation spectrum and warm plasma cases. In contrast to previous, single scatter theories, it is found...

  15. Impulsivity and Concussion in Juvenile Rats: Examining Molecular and Structural Aspects of the Frontostriatal Pathway.

    Science.gov (United States)

    Hehar, Harleen; Yeates, Keith; Kolb, Bryan; Esser, Michael J; Mychasiuk, Richelle

    2015-01-01

    Impulsivity and poor executive control have been implicated in the pathogenesis of many developmental and neuropsychiatric disorders. Similarly, concussions/mild traumatic brain injuries (mTBI) have been associated with increased risk for neuropsychiatric disorders and the development of impulsivity and inattention. Researchers and epidemiologists have therefore considered whether or not concussions induce symptoms of attention-deficit/hyperactivity disorder (ADHD), or merely unmask impulsive tendencies that were already present. The purpose of this study was to determine if a single concussion in adolescence could induce ADHD-like impulsivity and impaired response inhibition, and subsequently determine if inherent impulsivity prior to a pediatric mTBI would exacerbate post-concussion symptomology with a specific emphasis on impulsive and inattentive behaviours. As these behaviours are believed to be associated with the frontostriatal circuit involving the nucleus accumbens (NAc) and the prefrontal cortex (PFC), the expression patterns of 8 genes (Comt, Drd2, Drd3, Drd4, Maoa, Sert, Tph1, and Tph2) from these two regions were examined. In addition, Golgi-Cox staining of medium spiny neurons in the NAc provided a neuroanatomical examination of mTBI-induced structural changes. The study found that a single early brain injury could induce impulsivity and impairments in response inhibition that were more pronounced in males. Interestingly, when animals with inherent impulsivity experienced mTBI, injury-related deficits were exacerbated in female animals. The single concussion increased dendritic branching, but reduced synaptic density in the NAc, and these changes were likely associated with the increase in impulsivity. Finally, mTBI-induced impulsivity was associated with modifications to gene expression that differed dramatically from the gene expression pattern associated with inherent impulsivity, despite very similar behavioural phenotypes. Our findings suggest the need to tailor treatment strategies for mTBI in light of an individual's premorbid characteristics, given significant differences in molecular profiles of the frontostriatal circuits that depend upon sex and the etiology of the behavioural phenotype. PMID:26448536

  16. A compressed sensing based method with support refinement for impulse noise cancelation in DSL

    KAUST Repository

    Quadeer, Ahmed Abdul

    2013-06-01

    This paper presents a compressed sensing based method to suppress impulse noise in digital subscriber line (DSL). The proposed algorithm exploits the sparse nature of the impulse noise and utilizes the carriers, already available in all practical DSL systems, for its estimation and cancelation. Specifically, compressed sensing is used for a coarse estimate of the impulse position, an a priori information based maximum aposteriori probability (MAP) metric for its refinement, followed by least squares (LS) or minimum mean square error (MMSE) estimation for estimating the impulse amplitudes. Simulation results show that the proposed scheme achieves higher rate as compared to other known sparse estimation algorithms in literature. The paper also demonstrates the superior performance of the proposed scheme compared to the ITU-T G992.3 standard that utilizes RS-coding for impulse noise refinement in DSL signals. © 2013 IEEE.

  17. Managing Impulsive Interference in Impulse Radio UWB Networks

    OpenAIRE

    Flury, Manuel; Merz, Ruben; Le Boudec, Jean-Yves

    2007-01-01

    Wireless sensor networks are ideally built on low-cost, low-complexity nodes that have a low power consumption to guarantee a long network lifetime. These are all properties that can potentially be achieved with impulse radio ultra-wide band (IR-UWB). In addition, IR-UWB has a fine timing resolution resulting in accurate ranging and localization possible. For all these reasons, IR-UWB is an extremely interesting physical layer technology for wireless sensor networks. In this article, we consi...

  18. Epidemiologic and clinical updates on impulse control disorders: a critical review

    OpenAIRE

    DellOsso, Bernardo; Altamura, A Carlo; Allen, Andrea; Marazziti, Donatella; Hollander, Eric

    2006-01-01

    The article reviews the current knowledge about the impulse control disorders (ICDs) with specific emphasis on epidemiological and pharmacological advances. In addition to the traditional ICDs present in the DSM-IVpathological gambling, trichotillomania, kleptomania, pyromania and intermittent explosive disordera brief description of the new proposed ICDscompulsiveimpulsive (CI) Internet usage disorder, CI sexual behaviors, CI skin picking and CI shoppingis provided. Specifically, th...

  19. Modification of impulse generation during piqué turns with increased rotational demands.

    Science.gov (United States)

    Zaferiou, Antonia M; Wilcox, Rand R; McNitt-Gray, Jill L

    2016-06-01

    During initiation of a piqué turn, a dancer generates impulse to achieve the desired lateral translation and whole-body rotation. The goal of this study was to determine how individuals regulate impulse generation when initiating piqué turns with increased rotational demands. Skilled dancers (n=10) performed single (∼360°) and double (∼720°) piqué turns from a stationary position. Linear and angular impulse generated by the push and turn legs were quantified using ground reaction forces and compared across turn conditions as a group and within a dancer using probability-based statistical methods. The results indicate that as the rotation demands of the piqué turn increased, the net angular impulse generated increased whereas net lateral impulse decreased. Early during turn initiation, the free moment contributed to angular impulse generation. Later during turn initiation, horizontal reaction forces were controlled to generate angular impulse. As rotational demands increased, the moment applied increased primarily from redirection of the horizontal reaction force (RFh) at the push leg and a combination of RFh magnitude and moment arm increases at the turn leg. RFh at each leg were coordinated to limit unwanted net linear impulse. Knowledge of observed subject-specific mechanisms is important to inform the design of turning performance training tools. PMID:27038006

  20. Posttraumatic Stress Disorder's Underlying Dimensions and Their Relation With Impulsivity Facets.

    Science.gov (United States)

    Contractor, Ateka A; Armour, Cherie; Forbes, David; Elhai, Jon D

    2016-01-01

    Research indicates a significant relationship between posttraumatic stress disorder (PTSD) and impulsivity (Kotler, Julian, Efront, and Amir, J Nerv Ment Dis 189:162-167, 2001; Ledgerwood and Petry, J Trauma Stress 19:411-416, 2006). The present study assessed relations between PTSD symptom clusters and impulsivity subscales in an effort to assess the specific impulsivity component most related to PTSD's alterations in arousal/reactivity and alterations in mood/cognitions symptoms. In the current study, the PTSD Checklist for Diagnostic and Statistical Manual of Mental Disorders, 5th Edition, and the UPPS Impulsivity Scale were administered to a sample of 412 nonclinical subjects with a trauma history. Results indicated that PTSD's alterations in arousal/reactivity and mood/cognition factors were most related to impulsivity's sensation-seeking tendency compared with other impulsivity components. Results highlight the importance of assessing and addressing (1) sensation-seeking tendencies and (2) urges to act impulsively when experiencing negative affect in trauma treatment. Furthermore, it is possible that sensation-seeking tendencies are primarily driving the comorbidity between PTSD and certain impulsive behaviors. PMID:26558499

  1. A Review of Impulse Buying Behavior

    OpenAIRE

    G. Muruganantham; Ravi Shankar Bhakat

    2013-01-01

    Researchers and Practitioners have been interested in the field of impulse buying for the past sixty years (Clover,1950; Stern, 1962; Rook, 1987; Peck and Childers, 2006; Chang et.al, 2011). The purpose of this paper is toprovide a detailed account of the impulse buying behavior by compiling the various research works literature inthe field of Retailing and Consumer Behavior. It gives a broad overview of the impulse buying construct and thevarious behavior related aspects. A wide range of jou...

  2. Impulsive differential inclusions a fixed point approach

    CERN Document Server

    Ouahab, Abdelghani; Henderson, Johnny

    2013-01-01

    Impulsive differential equations have been developed in modeling impulsive problems in physics, population dynamics, ecology, biotechnology, industrial robotics, pharmacokinetics, optimal control, etc. The questions of existence and stability of solutions for different classes of initial values problems for impulsive differential equations and inclusions with fixed and variable moments are considered in detail. Attention is also given to boundary value problems and relative questions concerning differential equations. This monograph addresses a variety of side issues that arise from its simple

  3. Optimal Control of Volterra Equations with Impulses

    OpenAIRE

    Belbas, S. A.; Schmidt, W. H.

    2004-01-01

    We consider an optimal control problem for a system governed by a Volterra integral equation with impulsive terms. The impulses act on both the state and the control; the control consists of switchings at discrete times. The cost functional includes both, an integrated cost rate (continuous part) and switching costs at the discrete impulse times (discrete part). We prove necessary optimality conditions of a form analogous to a discrete maximum principle. For the particular case of a system go...

  4. Components of Impulsivity in Gambling Disorder

    OpenAIRE

    Hodgins, David C; Holub, Alice

    2015-01-01

    This study examined the structure of impulsivity within gambling disorder. A group of 51 men and 53 women with gambling disorder completed self-report and behavioral measures of impulsivity. Principal component analyses found two factors. The first was interpreted as measuring trait impulsivity. This factor correlated with problem gambling severity, presence of comorbid mental health and substance use disorders, history of brain injury, and was higher in Aboriginal participants. The second fa...

  5. Theory of impulsive differential equations

    CERN Document Server

    Lakshmikantham, V; Simeonov, Pavel S

    1989-01-01

    Many evolution processes are characterized by the fact that at certain moments of time they experience a change of state abruptly. These processes are subject to short-term perturbations whose duration is negligible in comparison with the duration of the process. Consequently, it is natural to assume that these perturbations act instantaneously, that is, in the form of impulses. It is known, for example, that many biological phenomena involving thresholds, bursting rhythm models in medicine and biology, optimal control models in economics, pharmacokinetics and frequency modulated systems, do e

  6. Transient impulsive electronic Raman redistribution.

    Science.gov (United States)

    Miyabe, S; Bucksbaum, P

    2015-04-10

    Resonant Raman excitation by ultrafast vacuum ultraviolet laser pulses is a powerful means to study electron dynamics in molecules, but experiments must contend with linear background ionization: frequencies high enough to reach resonant core-valence transitions will usually ionize all occupied orbitals as well, and the ionization cross sections are usually dominant. Here we show that attosecond pulses can induce a process, transient impulsive stimulated Raman scattering, which can overwhelm valence ionization. Calculations are performed for atomic sodium, but the principal is valid for many molecular systems. This approach opens the path for high-fidelity multidimensional spectroscopy with attosecond pulses. PMID:25910119

  7. Impulsive synchronization of networked nonlinear dynamical systems

    International Nuclear Information System (INIS)

    In this Letter, we investigate the problem of impulsive synchronization of networked multi-agent systems, where each agent can be modeled as an identical nonlinear dynamical system. Firstly, an impulsive control protocol is designed for network with fixed topology based on the local information of agents. Then sufficient conditions are given to guarantee the synchronization of the networked nonlinear dynamical system by using algebraic graph theory and impulsive control theory. Furthermore, how to select the discrete instants and impulsive constants is discussed. The case that the topologies of the networks are switching is also considered. Numerical simulations show the effectiveness of our theoretical results.

  8. Simplified calculation of detonation induced impulse

    International Nuclear Information System (INIS)

    Simplified methods of estimating the impulse generated by detonations propagating through gaseous fuel-oxidizer mixtures are developed. First the ground and dynamic impulse are defined. Self similar solutions are used to derive expressions for the ground and dynamic impulse of detonations confined clouds with plane, cylindrical, and spherical symmetry in terms of universal impulse functions which are independent of the detonation properties. A similar analysis is developed for clouds bounded by an inert gas which results in side relief. In this case the results are found to be in good agreement with experiment and with hydrocode calculations

  9. Impulsivity and the Sexes: Measurement and Structural Invariance of the UPPS-P Impulsive Behavior Scale

    Science.gov (United States)

    Cyders, Melissa A.

    2013-01-01

    Before it is possible to test whether men and women differ in impulsivity, it is necessary to evaluate whether impulsivity measures are invariant across sex. The UPPS-P Impulsive Behavior Scale (negative urgency, lack of premeditation, lack of perseverance, and sensation seeking, with added subscale of positive urgency) is one measure of five

  10. Impulsivity and the Sexes: Measurement and Structural Invariance of the UPPS-P Impulsive Behavior Scale

    Science.gov (United States)

    Cyders, Melissa A.

    2013-01-01

    Before it is possible to test whether men and women differ in impulsivity, it is necessary to evaluate whether impulsivity measures are invariant across sex. The UPPS-P Impulsive Behavior Scale (negative urgency, lack of premeditation, lack of perseverance, and sensation seeking, with added subscale of positive urgency) is one measure of five…

  11. Reliability and validity of measures of impulsive choice and impulsive action in smokers trying to quit.

    Science.gov (United States)

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

    2016-04-01

    Cross-sectional research suggests that smokers are more impulsive than are nonsmokers, 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 postquit, whereas impulsive action was less stable. Test-retest reliability from prequit to 3 weeks' postquit was moderated by achievement of 7-day abstinence. Baseline impulsive action was significantly negatively related to quitting for at least 1 day in the first 2 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 7-day point-prevalence abstinence 12 weeks' postquit, 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 intercorrelation, differential stability, and differential relations with abstinence. Impulsive action may impede initial quitting, whereas impulsive choice may be an obstacle to maintaining lasting abstinence. (PsycINFO Database Record PMID:26751623

  12. Hyperkinetic Impulse Disorder in Children's Behavior Problems

    Science.gov (United States)

    Laufer, Maurice W.; Denhoff, Eric; Solomons, Gerald

    2011-01-01

    A very common cause of children's behavior disorder disturbance is an entity described as the hyperkinetic impulse disorder. This is characterized by hyperactivity, short attention span and poor powers of concentration, irritability, impulsiveness, variability, and poor schoolwork. The existence of this complexity may lead to many psychological…

  13. Development and implementation of a new ultrafast imaging diagnostic for laboratory magnetoplasma: application in the plasma radial transport characterization

    International Nuclear Information System (INIS)

    Non intrusive diagnostics have been developed in order to increase the precision in the data obtained from plasmas in a turbulent state. This thesis was carried on the development and the implementation of a new diagnostic for laboratory plasmas, i.e. an ultra-fast imaging system recording the spontaneous light emission, applied in turbulent plasmas of a magnetoplasma. The low resolution camera is composed of an array of photodetectors, their sensibility is centered on the main wavelength of the studied plasmas. Moreover, records can be longer than fifty milliseconds, even with a 100.000 frames per second recording frequency. This camera allows a precise study of both the spatial evolution of a phenomena and a statistical analysis of the recorded turbulent signal. Our prototype has been used to record different instable regimes of the laboratory magnetized plasma device. The main goal of this thesis was on the development and on the validation of this new diagnostic. Further studies will be devoted to the identification of the instabilities and underlying mechanisms. (author)

  14. Self-confined plasma in a magneto-plasma compressor and the influence of an externally imposed magnetic field

    International Nuclear Information System (INIS)

    The spatial profile of a magnetically self-confined plasma formed by a magneto-plasma compressor is measured in radial and axial direction with an array of Faraday cups, and radiation with a wavelength as short as extreme ultraviolet is detected. A Gaussian distribution approximates the radial profile of the ion current density. Along the axis, the ion current density remains approximately constant up to 2.25 inner anode radii from the electrodes end, before diverging. The plasma stream is further compressed by the addition of an external magnetic field. The external magnetic field is measured and is close to the self-induced magnetic field. The measurements of the profile show an increase in the ion current density after the inlet into the external magnetic field. The ion current density at 3.25 inner anode radii from the end of the electrodes doubles, and the width of the plasma stream decreases. Estimations show that the increase of the ion current density is also due to an increase of around 25% of the mean ion charge, hence to a temperature increase of around 50% enhancing photon emission at shorter wavelength. A design guideline is presented to dimensionalize the amplitude of the external magnetic field depending on the wanted temperature increase in the plasma stream. (paper)

  15. Impulse Regulation in Anorexia Nervosa and Bulimia Nervosa: Some Formulations

    OpenAIRE

    Staffan Sohlberg

    1991-01-01

    Empirical observations imply that impulsivity is specifically associated with poor prognosis in eating disorders. The present paper cites studies suggesting that this factor is predominantly associated with the bulimic pattern of eating disturbance, while restriction may be associated rather with hypercontrol of behaviour. Further evidence is cited suggesting that the relationship between hyper- and hypocontrol is actually very intimate, both on a behavioural and biochemical level. Rather t...

  16. Sex differences moderate decision making behaviour in high impulsive sensation seekers.

    Science.gov (United States)

    Dretsch, Michael N; Tipples, Jason

    2011-01-01

    We tested whether individuals with high levels of impulsive sensation seeking learn to choose advantageously in a specific decision-making context. One hundred twenty-eight participants (73 female) completed a neuropsychological task, the variant version of the Iowa Gambling Task (vIGT; Bechara, Tranel, & Damasio, 2000), in which individuals must select cards from decks that offer high initial losses if they are to eventually make a profit. The selection from decks of cards that led to the highest profit as the task progressed was higher in high, compared to low, impulsive sensation seekers. However, learning to choose advantageously was moderated by sex of participant. Specifically, compared to females, male high impulsive sensation seekers learned more quickly to make consistent selections from the advantageous decks despite the large immediate losses. Overall, the data support the hypothesis that insensitivity to loss due to impulsive sensation seeking can lead to financial gain. PMID:21432662

  17. Impulse position control algorithms for nonlinear systems

    Science.gov (United States)

    Sesekin, A. N.; Nepp, A. N.

    2015-11-01

    The article is devoted to the formalization and description of impulse-sliding regime in nonlinear dynamical systems that arise in the application of impulse position controls of a special kind. The concept of trajectory impulse-sliding regime formalized as some limiting network element Euler polygons generated by a discrete approximation of the impulse position control This paper differs from the previously published papers in that it uses a definition of solutions of systems with impulse controls, it based on the closure of the set of smooth solutions in the space of functions of bounded variation. The need for the study of such regimes is the fact that they often arise when parry disturbances acting on technical or economic control system.

  18. Recreational drug use and impulsivity in a population of Canadian undergraduate drinkers

    Directory of Open Access Journals (Sweden)

    IrisMBalodis

    2010-10-01

    Full Text Available The consumption of drugs during young adulthood may be particularly detrimental given important neurodevelopmental changes occurring during this period. As impulsivity may lead to substance use and substance use to the commission of seemingly impulsive acts, an improved understanding of the relationship between alcohol use, other substance use and impulsivity in young adults is important. We gathered information on self-reported impulsivity, recreational drug use, and drinking habits of 205 (105 female undergraduate students. Results showed that 64% of the students reported using marijuana at least once and these individuals were more likely to report binge drinking. Polydrug use, defined as using marijuana and at least one other illicit substance, was reported by 20% of students. These individuals reported more drinking occasions per month and had higher levels of trait impulsivity. Rates of recreational drug use were similar to those reported in recent national surveys, suggesting an increase in experimentation with specific illicit drugs. Given that a majority of undergraduate drinkers reported marijuana use and its association with binge drinking, future research should clarify the relationship between marijuana use and binge consumption of alcohol and prevention efforts should consider the conjoint targeting of marijuana and binge drinking. The associations between polydrug use, binge-level alcohol consumption and elevated self-reported impulsivity suggests that perceived trait impulsivity across multiple domains may predispose to excessive use of multiple substances. Longitudinal studies should examine the contribution of impulsivity to the initiation and experimentation with illicit drugs and the influence of specific substances on impulsivity.

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

    Science.gov (United States)

    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.

  20. Impulsivity, impulsive and reflective processes and the development of alcohol use and misuse in adolescents and young adults.

    OpenAIRE

    Wiers, R.W.; Ames, S.L.; Hofmann, W.; Krank, M.; Stacy, A.W.

    2010-01-01

    This paper contrasts dual-process and personality approaches in the prediction of addictive behaviors and related risk behaviors. In dual-process models, behavior is described as the joint outcome of qualitatively different "impulsive" (or associative) and "reflective" processes. There are important individual differences regarding both types of processes, and the relative strength of both in a specific situation is influenced by prior behavior and state variables (e.g., fatigue, alcohol use)...

  1. Differences and similarities between impulse buying and variety seeking: A personality-based perspective

    DEFF Research Database (Denmark)

    Olsen, Svein Ottar; Tudoran, Ana Alina; Honkanen, Pirjo; Verplanken, Bas

    2016-01-01

    Although personality is a key determinant of consumer purchasing decision making, the role of personality traits on impulse buying and variety seeking is not conclusive. This research uses a personality perspective to determine the unique associations between impulse buying tendency (IBT), variety......: Neuroticism and Openness to Experience. Specifically, the present study indicates that Neuroticism predicted IBT positively and VST negatively, while Openness was a strong predictor of VST and unrelated to IBT....

  2. Ion-Acoustic Vortices in Two-Electron-Temperature Magnetoplasma with Cairn's Distributed Electrons and in the Presence of Ion Shear Flow

    Science.gov (United States)

    Haque, Q.; Mirza, Arshad M.; Iqbal, Javed

    2016-04-01

    Linear and nonlinear characteristics of electrostatic waves in a multicomponent magnetoplasma comprising of Boltzmann distributed electrons, Cairn's distributed hot electrons, and cold dynamic ions are studied. It is found that the effect of superthermal electrons, ion-neutral collisions, and ion shear flow modifies the propagation of ion-acoustic and drift waves. The growth rate of the ion shear flow instability varies with the addition of Cairn's distributed hot electrons. It is also investigated that the behavior of different type of vortices changes with the inclusion of superthermal hot electrons. The relevance of this investigation in space plasmas such as in auroral region and geomagnetic tail is also pointed out.

  3. Impulsivity and emotion dysregulation as predictors of food addiction.

    Science.gov (United States)

    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 psaddiction, elucidate causal mechanisms, and support an explanatory model of food addiction. PMID:26164390

  4. Self-focusing of a Hermite-cosh Gaussian laser beam in a magnetoplasma with ramp density profile

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, Vikas; Kant, Niti; Wani, Manzoor Ahmad [Department of Physics, Lovely Professional University, Phagwara 144411, Punjab (India)

    2013-11-15

    The early and strong self-focusing of a Hermite-cosh-Gaussian laser beam in magnetoplasma in the presence of density ramp has been observed. Focusing and de-focusing nature of the Hermite-cosh-Gaussian laser beam with decentered parameter and magnetic field has been studied, and strong self-focusing is reported. It is investigated that decentered parameter 'b' plays a significant role for the self-focusing of the laser beam and is very sensitive as in case of extraordinary mode. For mode indices, m = 0, 1, 2, and b = 4.00, 3.14, and 2.05, strong self-focusing is observed. Similarly in case of ordinary mode, for m = 0, 1, 2 and b = 4.00, 3.14, 2.049, respectively, strong self-focusing is reported. Further, it is seen that extraordinary mode is more prominent toward self-focusing rather than ordinary mode of propagation. For mode indices m = 0, 1, and 2, diffraction term becomes more dominant over nonlinear term for decentered parameter b=0. For selective higher values of decentered parameter in case of mode indices m=0, 1, and 2, self-focusing effect becomes strong for extraordinary mode. Also increase in the value of magnetic field enhances the self-focusing ability of the laser beam, which is very useful in the applications like the generation of inertial fusion energy driven by lasers, laser driven accelerators, and x-ray lasers.

  5. Self-focusing of a Hermite-cosh Gaussian laser beam in a magnetoplasma with ramp density profile

    International Nuclear Information System (INIS)

    The early and strong self-focusing of a Hermite-cosh-Gaussian laser beam in magnetoplasma in the presence of density ramp has been observed. Focusing and de-focusing nature of the Hermite-cosh-Gaussian laser beam with decentered parameter and magnetic field has been studied, and strong self-focusing is reported. It is investigated that decentered parameter 'b' plays a significant role for the self-focusing of the laser beam and is very sensitive as in case of extraordinary mode. For mode indices, m = 0, 1, 2, and b = 4.00, 3.14, and 2.05, strong self-focusing is observed. Similarly in case of ordinary mode, for m = 0, 1, 2 and b = 4.00, 3.14, 2.049, respectively, strong self-focusing is reported. Further, it is seen that extraordinary mode is more prominent toward self-focusing rather than ordinary mode of propagation. For mode indices m = 0, 1, and 2, diffraction term becomes more dominant over nonlinear term for decentered parameter b=0. For selective higher values of decentered parameter in case of mode indices m=0, 1, and 2, self-focusing effect becomes strong for extraordinary mode. Also increase in the value of magnetic field enhances the self-focusing ability of the laser beam, which is very useful in the applications like the generation of inertial fusion energy driven by lasers, laser driven accelerators, and x-ray lasers

  6. Obtaining Binaural Room Impulse Responses from B-Format Impulse Responses

    OpenAIRE

    Menzer, Fritz; Faller, Christof

    2008-01-01

    Given a set of head related transfer functions (HRTFs) and a room impulse response measured with a Soundfield microphone, the proposed technique computes binaural room impulse responses (BRIRs) which are similar to binaural room impulse responses that would be measured if in place of the Soundfield microphone, the dummy head used for the HRTF set was directly recording the BRIRs. The proposed technique enables that from a set of HRTFs corresponding BRIRs for different rooms are ob...

  7. AGGRESSION AND IMPULSIVITY WITH IMPULSIVE BEHAVIOURS IN PATIENTS WITH PURGATIVE ANOREXIA AND BULIMIA NERVOSA

    OpenAIRE

    Zalar, Bojan; Weber, Urka; Sernec, Karin

    2011-01-01

    Background: The study aimed to compare purgative anorexia and bulimia nervosa patients in regard of their level of aggression and impulsivity traits, as well as dynamics of selected impulsive behaviours over time-course of eating disorder treatment. Subjects and methods: 30 females with purgative anorexia nervosa, 33 females with purgative bulimia nervosa and 31 controls were included. Impulsive behaviours were assessed upon hospital admission, discharge, and three and six months aft...

  8. Detecting Impulses in Mechanical Signals by Wavelets

    Directory of Open Access Journals (Sweden)

    Yang W-X

    2004-01-01

    Full Text Available The presence of periodical or nonperiodical impulses in vibration signals often indicates the occurrence of machine faults. This knowledge is applied to the fault diagnosis of such machines as engines, gearboxes, rolling element bearings, and so on. The development of an effective impulse detection technique is necessary and significant for evaluating the working condition of these machines, diagnosing their malfunctions, and keeping them running normally over prolong periods. With the aid of wavelet transforms, a wavelet-based envelope analysis method is proposed. In order to suppress any undesired information and highlight the features of interest, an improved soft threshold method has been designed so that the inspected signal is analyzed in a more exact way. Furthermore, an impulse detection technique is developed based on the aforementioned methods. The effectiveness of the proposed technique on the extraction of impulsive features of mechanical signals has been proved by both simulated and practical experiments.

  9. Impulsive fractional differential inclusions with infinite delay

    Directory of Open Access Journals (Sweden)

    Khalida Aissani

    2013-11-01

    Full Text Available In this article, we apply Bohnenblust-Karlin's fixed point theorem to prove the existence of mild solutions for a class of impulsive fractional equations inclusions with infinite delay. An example is given to illustrate the theory.

  10. Quantum Fluctuations for Gravitational Impulsive Waves

    OpenAIRE

    Enginer, Y.; Hortacsu, M.; Ozdemir, N.

    1998-01-01

    Quantum fluctuations for a massless scalar field in the background metric of spherical impulsive gravitational waves through Minkowski and de Sitter spaces are investigated. It is shown that there exist finite fluctuations for de Sitter space.

  11. Impulse breakdown delay in liquid dielectrics

    OpenAIRE

    Jadidian, Jouya; Zahn, Markus; Lavesson, Nils; Widlund, Ola; Borg, Karl

    2012-01-01

    Theoretical images of streamers, revealing the mechanisms behind impulse breakdown in liquid dielectrics, are presented. Streamers lead to electrical breakdown by forming paths, capable of carrying large current amplitudes between electrodes. Breakdown delays and terminal currents are calculated for various electrode geometries (40 μm needle and 6.35 mm sphere) and gap distances (up to 10 mm). Modeling results indicate that the breakdown in needle-needle electrodes requires higher impulse vol...

  12. Anger and Impulsivity in Adolescents Attempting Suicide

    OpenAIRE

    Elif AKIN; BERKEM, Meral

    2012-01-01

    Objective: We aimed to evaluate anger and impulsivity in adolescent suicide attempters between the ages of 12 and 18, compared with control group; investigate the relation between hostility, impulsivity and suicide intent.Patients and Methods: Thirty-six adolescent patients between the ages of 12 and 18 referred to the Marmara University Hospital, Child and Adolescent Psychiatry Policlinic because of attempted suicide between June 2009 and May 2010, were included in the study. Thirty-four hea...

  13. Leupeptin reduces impulse noise induced hearing loss

    OpenAIRE

    Gavriel Haim; Shulman Abraham; Stracher Alfred; Sohmer Haim

    2011-01-01

    Abstract Background Exposure to continuous and impulse noise can induce a hearing loss. Leupeptin is an inhibitor of the calpains, a family of calcium-activated proteases which promote cell death. The objective of this study is to assess whether Leupeptin could reduce the hearing loss resulting from rifle impulse noise. Methods A polyethelene tube was implanted into middle ear cavities of eight fat sand rats (16 ears). Following determination of auditory nerve brainstem evoked response (ABR) ...

  14. Neural substrates of time perception and impulsivity

    OpenAIRE

    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 impul...

  15. Forensic Psychiatric Aspects of Impulse Control Disorders

    Directory of Open Access Journals (Sweden)

    Huseyin Soysal

    2015-03-01

    Full Text Available Impulse control disorders is an important psychiatric disorder group which draws attention in recent years. Attention deficit hyperactivity disorder and other classical disorders like pyromania, kleptomania, intermittent explosive disorder and compulsive buying could be evasuated under this topic. The aim of this article is to review forensic psychiatric aspects of impulse control disorders and evaluate the disorders in terms of their legal status. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2015; 7(1: 16-29

  16. Anger and Impulsivity in Adolescents Attempting Suicide

    Directory of Open Access Journals (Sweden)

    Elif AKIN

    2012-01-01

    Full Text Available Objective: We aimed to evaluate anger and impulsivity in adolescent suicide attempters between the ages of 12 and 18, compared with control group; investigate the relation between hostility, impulsivity and suicide intent.Patients and Methods: Thirty-six adolescent patients between the ages of 12 and 18 referred to the Marmara University Hospital, Child and Adolescent Psychiatry Policlinic because of attempted suicide between June 2009 and May 2010, were included in the study. Thirty-four healthy subjects were selected as control group. Clinical assessment of participants was made with the Kiddie Schedule for Affective Disorders and Schizophrenia Present and Life Time Version. Adolescents were also evaluated with the Spielberg State Trait Anger Expression Inventory and Barratt's Impulsivity Scale. The seriousness of attempted suicide in adolescents was determined with the Suicide Intent Scale.Results: Average total and subscores (except anger control subscore of anger and impulsivity scales were found higher in adolescents attempting suicide than in control group (p0.05.Conclusion: Anger and impulsivity merit attention in adolescent attempted suicides. Additionally, our results reinforce the need for further studies investigating the relation between personality traits, psychiatric, familial and social factors for better understanding of the effect of anger and impulsivity in adolescent suicide behavior. (Marmara Medical Journal 2012;25:148-52

  17. 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

    Science.gov (United States)

    Maglich, Bogdan; Hester, Tim; Calsec Collaboration

    2015-10-01

    Uranium-uranium colliding beam experiment1, used fully ionized 238U92+ at energy 100GeV --> ions accelerated through 3 MV accelerator, will collide beam 240 MeV --> 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.

  18. Teens Impulsively React Rather than Retreat from Threat

    Science.gov (United States)

    Dreyfuss, Michael; Caudle, Kristina; Drysdale, Andrew T.; Johnston, Natalie E.; Cohen, Alexandra O.; Somerville, Leah H.; Galván, Adriana; Tottenham, Nim; Hare, Todd A.; Casey, BJ

    2014-01-01

    There is a significant inflection in risk taking and criminal behavior during adolescence, but the basis for this increase remains largely unknown. An increased sensitivity to rewards has been suggested to explain these behaviors. Yet juvenile offenses often occur in emotionally charged situations of negative valence. How behavior is altered by changes in negative emotional processes during adolescence has received less attention than changes in positive emotional processes. The current study uses a measure of impulsivity in combination with cues that signal threat or safety to assess developmental changes in emotional responses to threat cues. We show that adolescents, especially males, impulsively react to threat cues relative to neutral ones, more than adults or children, even when instructed not to respond. This adolescent specific behavioral pattern is paralleled by enhanced activity in limbic cortical regions implicated in detection and assignment of emotional value to inputs and in the subsequent regulation of responses to them when successfully suppressing impulsive responses to threat cues. In contrast, prefrontal control regions implicated in detecting and resolving competing responses show an adolescent emergent pattern (i.e., greater activity in adolescents and adults relative to children) during successful suppression of a response regardless of emotion. Our findings suggest that adolescence is a period of heightened sensitivity to social and emotional cues that results in diminished regulation of behavior in their presence. PMID:24821576

  19. Narcissism predicts impulsive buying: phenotypic and genetic evidence

    OpenAIRE

    Cai, Huajian; Shi, Yuanyuan; Fang, Xiang; Luo, Yu L.L.

    2015-01-01

    Impulsive buying makes billions of dollars for retail businesses every year, particularly in an era of thriving e-commerce. Narcissism, characterized by impulsivity and materialism, may serve as a potential antecedent to impulsive buying. To test this hypothesis, two studies examined the relationship between narcissism and impulsive buying. In Study 1, we surveyed an online sample and found that while adaptive narcissism was not correlated with impulsive buying, maladaptive narcissism was sig...

  20. Reliable impulsive synchronization for a class of nonlinear chaotic systems

    International Nuclear Information System (INIS)

    The problem of reliable impulsive synchronization for a class of nonlinear chaotic systems has been investigated in this paper. Firstly a reliable impulsive controller is designed by using the impulsive control theory. Then by the uniform asymptotic stability criteria of systems with impulsive effects, some sufficient conditions for reliable impulsive synchronization between the drive system and the response system are obtained. Numerical simulations are given to show the effectiveness of the proposed method. (general)

  1. Environmental Rearing Effects on Impulsivity and Reward Sensitivity

    OpenAIRE

    Kirkpatrick, Kimberly; Marshall, Andrew T; Clarke, Jacob; Cain, Mary E.

    2013-01-01

    Previous research has indicated that rearing in an enriched environment may promote self-control in an impulsive choice task. To further assess the effects of rearing environment on impulsivity, 2 experiments examined locomotor activity, impulsive action, impulsive choice, and different aspects of reward sensitivity and discrimination. In Experiment 1, rats reared in isolated or enriched conditions were tested on an impulsive choice procedure with a smaller-sooner versus a larger-later reward...

  2. BMI predicts emotion-driven impulsivity and cognitive inflexibility in adolescents with excess weight.

    Science.gov (United States)

    Delgado-Rico, Elena; Ro-Valle, Jacqueline S; Gonzlez-Jimnez, Emilio; Campoy, Cristina; Verdejo-Garca, Antonio

    2012-08-01

    Adolescent obesity is increasingly viewed as a brain-related dysfunction, whereby reward-driven urges for pleasurable foods "hijack" response selection systems, such that behavioral control progressively shifts from impulsivity to compulsivity. In this study, we aimed to examine the link between personality factors (sensitivity to reward (SR) and punishment (SP), BMI, and outcome measures of impulsivity vs. flexibility in--otherwise healthy--excessive weight adolescents. Sixty-three adolescents (aged 12-17) classified as obese (n = 26), overweight (n = 16), or normal weight (n = 21) participated in the study. We used psychometric assessments of the SR and SP motivational systems, impulsivity (using the UPPS-P scale), and neurocognitive measures with discriminant validity to dissociate inhibition vs. flexibility deficits (using the process-approach version of the Stroop test). We tested the relative contribution of age, SR/SP, and BMI on estimates of impulsivity and inhibition vs. switching performance using multistep hierarchical regression models. BMI significantly predicted elevations in emotion-driven impulsivity (positive and negative urgency) and inferior flexibility performance in adolescents with excess weight--exceeding the predictive capacity of SR and SP. SR was the main predictor of elevations in sensation seeking and lack of premeditation. These findings demonstrate that increases in BMI are specifically associated with elevations in emotion-driven impulsivity and cognitive inflexibility, supporting a dimensional path in which adolescents with excess weight increase their proneness to overindulge when under strong affective states, and their difficulties to switch or reverse habitual behavioral patterns. PMID:22421897

  3. Do online assessed self-report and behavioral measures of impulsivity-related constructs predict onset of substance use in adolescents?

    OpenAIRE

    2015-01-01

    Introduction: To prospectively predict the onset of use of alcohol, cigarettes and marijuana among Dutch adolescents, using behavioral and self-report measures of impulsivity-related facets. Specifically, we investigated whether behavioral measures of impulsivity predicted the onset of substance use above and beyond self-report measures of impulsivity and sensation seeking in an online sample. Methods: Self-report and behavioral data from 284 adolescents (195 girls, mean age = 14.8 years, SD ...

  4. Neural substrates of time perception and impulsivity.

    Science.gov (United States)

    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. PMID:21763642

  5. Neural substrates of time perception and impulsivity

    Science.gov (United States)

    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

  6. Impulsive corporal punishment by mothers and antisocial behavior and impulsiveness of children.

    Science.gov (United States)

    Straus, M A; Mouradian, V E

    1998-01-01

    This study tested the hypothesis that corporal punishment (CP), such as spanking or slapping a child for purposes of correcting misbehavior, is associated with antisocial behavior (ASB) and impulsiveness by the child. The data were obtained through interviews with a probability sample of 933 mothers of children age 2-14 in two small American cities. Analyses of variance found that the more CP experienced by the child, the greater the tendency for the child to engage in ASB and to act impulsively. These relationships hold even after controlling for family socioeconomic status, the age and sex of the child, nurturance by the mother, and the level of noncorporal interventions by the mother. There were also significant interaction effects of CP with impulsiveness by the mother. When CP was carried out impulsively, it was most strongly related to child impulsiveness and ASB; when CP was done when the mother was under control, the relationship to child behavior problems was reduced but still present. In view of the fact that there is a high risk of losing control when engaged in CP, even by parents who are not usually impulsive, and the fact that impulsive CP is so strongly associated with child behavior problems, the results of this study suggest that CP is an important risk factor for children developing a pattern of impulsive and antisocial behavior which, in turn, may contribute to the level of violence and other crime in society. PMID:9768466

  7. Impulse-control disorders in alcoholics are related to sensation seeking and not to impulsivity.

    Science.gov (United States)

    Lejoyeux, M; Feuch, N; Loi, S; Solomon, J; Ads, J

    1998-11-16

    Impulse-control disorders (ICD) include intermittent explosive disorder, kleptomania, trichotillomania, pyromania and pathological gambling. Several studies have suggested that the incidence of pathological gambling and impulsive violent behavior is substantially higher in alcohol-dependent patients than in the general population. The association between ICD and alcoholism, as well as personality characteristics such as sensation seeking and impulsivity, has never been systematically studied. The present study compared the levels of impulsivity and sensation seeking in age- and sex-matched groups of alcohol-dependent patients with concomitant ICD (ICD+, n = 30), alcohol-dependent patients without ICD (ICD-; n = 30) and control subjects (n = 30). All the alcohol-dependent patients (ICD+ and ICD-) were hospitalized for alcohol detoxification. Diagnoses of ICD were based on DSM-IV criteria and the Minnesota Impulsive Disorders Interview. All patients completed the Zuckerman Sensation-Seeking Scale (SSS) and the Barratt Impulsiveness Rating Scale (BIS). Mean scores on the SSS general factor, the SSS disinhibition subscale, and the SSS experience-seeking scale were significantly higher in ICD+ patients than in either ICD- patients or control subjects. By contrast, total scores and subscale scores on the BIS showed no significant differences among the three groups. Thus, it appears that measures of sensation seeking, rather than impulsivity, are relevant in distinguishing between alcohol-dependent patients with and without concomitant impulse control disorders. PMID:9858032

  8. Characterization of impulse noise and hazard analysis of impulse noise induced hearing loss using AHAAH modeling

    Science.gov (United States)

    Wu, Qing

    Millions of people across the world are suffering from noise induced hearing loss (NIHL), especially under working conditions of either continuous Gaussian or non-Gaussian noise that might affect human's hearing function. Impulse noise is a typical non-Gaussian noise exposure in military and industry, and generates severe hearing loss problem. This study mainly focuses on characterization of impulse noise using digital signal analysis method and prediction of the auditory hazard of impulse noise induced hearing loss by the Auditory Hazard Assessment Algorithm for Humans (AHAAH) modeling. A digital noise exposure system has been developed to produce impulse noises with peak sound pressure level (SPL) up to 160 dB. The characterization of impulse noise generated by the system has been investigated and analyzed in both time and frequency domains. Furthermore, the effects of key parameters of impulse noise on auditory risk unit (ARU) are investigated using both simulated and experimental measured impulse noise signals in the AHAAH model. The results showed that the ARUs increased monotonically with the peak pressure (both P+ and P-) increasing. With increasing of the time duration, the ARUs increased first and then decreased, and the peak of ARUs appeared at about t = 0.2 ms (for both t+ and t-). In addition, the auditory hazard of experimental measured impulse noises signals demonstrated a monotonically increasing relationship between ARUs and system voltages.

  9. Impulsivity and Concussion in Juvenile Rats: Examining Molecular and Structural Aspects of the Frontostriatal Pathway

    Science.gov (United States)

    Hehar, Harleen; Yeates, Keith; Kolb, Bryan; Esser, Michael J.; Mychasiuk, Richelle

    2015-01-01

    Impulsivity and poor executive control have been implicated in the pathogenesis of many developmental and neuropsychiatric disorders. Similarly, concussions/mild traumatic brain injuries (mTBI) have been associated with increased risk for neuropsychiatric disorders and the development of impulsivity and inattention. Researchers and epidemiologists have therefore considered whether or not concussions induce symptoms of attention-deficit/hyperactivity disorder (ADHD), or merely unmask impulsive tendencies that were already present. The purpose of this study was to determine if a single concussion in adolescence could induce ADHD-like impulsivity and impaired response inhibition, and subsequently determine if inherent impulsivity prior to a pediatric mTBI would exacerbate post-concussion symptomology with a specific emphasis on impulsive and inattentive behaviours. As these behaviours are believed to be associated with the frontostriatal circuit involving the nucleus accumbens (NAc) and the prefrontal cortex (PFC), the expression patterns of 8 genes (Comt, Drd2, Drd3, Drd4, Maoa, Sert, Tph1, and Tph2) from these two regions were examined. In addition, Golgi-Cox staining of medium spiny neurons in the NAc provided a neuroanatomical examination of mTBI-induced structural changes. The study found that a single early brain injury could induce impulsivity and impairments in response inhibition that were more pronounced in males. Interestingly, when animals with inherent impulsivity experienced mTBI, injury-related deficits were exacerbated in female animals. The single concussion increased dendritic branching, but reduced synaptic density in the NAc, and these changes were likely associated with the increase in impulsivity. Finally, mTBI-induced impulsivity was associated with modifications to gene expression that differed dramatically from the gene expression pattern associated with inherent impulsivity, despite very similar behavioural phenotypes. Our findings suggest the need to tailor treatment strategies for mTBI in light of an individuals premorbid characteristics, given significant differences in molecular profiles of the frontostriatal circuits that depend upon sex and the etiology of the behavioural phenotype. PMID:26448536

  10. 20mN, Variable Specific Impulse Colloid Thruster Project

    Data.gov (United States)

    National Aeronautics and Space Administration — During Phase I, Busek designed and manufactured an electrospray emitter capable of generating 20 mN in a 7" x 7" x 1.7" package. The thruster consists of nine...

  11. Human impulsive aggression: a sleep research perspective.

    Science.gov (United States)

    Lindberg, Nina; Tani, Pekka; Appelberg, Björn; Naukkarinen, Hannu; Rimón, Ranan; Porkka-Heiskanen, Tarja; Virkkunen, Matti

    2003-01-01

    Impulsive aggression is commonly associated with personality disorders, in particular antisocial and borderline personality disorders as well as with conduct disorder and intermittent explosive disorder. The relationship between impulsive aggression and testosterone is well established in many studies. One of the aims of this study was to characterize the relationship between earlier-mentioned different categorical psychiatric diagnosis describing human impulsive aggression and sleep using polysomnography and spectral power analysis. Another aim was to study the relationship between serum testosterone and sleep in persons with severe aggressive behaviour. Subjects for the study were 16 males charged with highly violent offences and ordered for a pretrial forensic psychiatric examination. The antisocials with borderline personality disorder comorbidity had significantly more awakenings and lower sleep efficiency compared with the subjects with only antisocial personality disorder. The subjects with severe conduct disorder in childhood anamnesis had higher amount of S4 sleep and higher relative theta and delta power in this sleep stage compared with males with only mild or moderate conduct disorder. The same kind of sleep architecture was associated with intermittent explosive disorder. In subgroups with higher serum testosterone levels also the amount of S4 sleep and the relative theta and delta power in this sleep stage were increased. The study gives further support to the growing evidence of brain dysfunction predisposing to severe aggressive behaviour and strengthens the view that there are different subpopulations of individuals with antisocial personality varying in impulsiveness. The differences in impulsiveness are reflected in sleep architecture as well. PMID:12765854

  12. Entrainment and the cranial rhythmic impulse.

    Science.gov (United States)

    McPartland, J M; Mein, E A

    1997-01-01

    Entrainment is the integration or harmonization of oscillators. All organisms pulsate with myriad electrical and mechanical rhythms. Many of these rhythms emanate from synchronized pulsating cells (eg, pacemaker cells, cortical neurons). The cranial rhythmic impulse is an oscillation recognized by many bodywork practitioners, but the functional origin of this impulse remains uncertain. We propose that the cranial rhythmic impulse is the palpable perception of entrainment, a harmonic frequency that incorporates the rhythms of multiple biological oscillators. It is derived primarily from signals between the sympathetic and parasympathetic nervous systems. Entrainment also arises between organisms. The harmonizing of coupled oscillators into a single, dominant frequency is called frequency-selective entrainment. We propose that this phenomenon is the modus operandi of practitioners who use the cranial rhythmic impulse in craniosacral treatment. Dominant entrainment is enhanced by "centering," a technique practiced by many healers, for example, practitioners of Chinese, Tibetan, and Ayurvedic medicine. We explore the connections between centering, the cranial rhythmic impulse, and craniosacral treatment. PMID:8997803

  13. Conception et caracterisation d'un magnetoplasma produit par une onde de surface pour la pulverisation d'echantillons solides

    Science.gov (United States)

    Masse, Louis Philippe

    Suite a l'extraordinaire explosion de l'informatique de la derniere decennie, la science et la technologie des materiaux ont pris un essor extraordinaire. Par exemple, il est devenu crucial de concevoir des materiaux a haut degre de purete. Ce besoin a fortement motive le developpement de methodes d'analyse de solides. Traditionnellement, la methode adoptee est l'analyse par torche ICP, mais pour de nombreuses raisons, dont la lenteur de cette methode, la communaute scientifique oeuvrant en chimie analytique recherche des techniques d'analyse de solides directes, rapides et plus sensibles. Parmi les voies possibles, on trouve les methodes basees sur la pulverisation par plasma. Dans ce contexte, nous avons etudie la possibilite et la pertinence d'utiliser un magnetoplasma entretenu par une onde de surface pour pulveriser des solides dans le but de les analyser. Nos travaux portent principalement sur l'etude du comportement du plasma lors de la pulverisation. Nous avons montre que la pulverisation affecte la decharge de diverses facons. En premier lieu, la concentration d'especes provenant du materiau pulverise dans le plasma augmente avec la tension de polarisation. De plus, la concentration d'especes pulverisees diminue lorsque la pression croit, possiblement a cause du redepot. Nous avons aussi montre qu'il etait possible de pulveriser des solides isolants en exploitant le phenomene d'autopolarisation du a l'application d'une tension RF. Nous avons aussi etudie l'effet de la pulverisation sur la temperature et la densite electronique. Ainsi, lors de la pulverisation de metaux tels que le cuivre, la temperature electronique diminue lorsque la tension de polarisation augmente. Ceci est attribuable a l'augmentation de la densite d'especes metalliques neutres facilement ionisables par impact electronique. Nous avons aussi note que la densite electronique augmente avec la concentration d'especes metalliques dans le plasma, ce qui resulte d'un meilleur bilan de puissance. Une etude des caracteristiques du plasma seul a revele que le champ magnetique confine si bien le plasma que le maximum de densite electronique se trouve hors axe, plus exactement a la position radiale correspondant au rayon du cylindre dielectrique servant a former l'interface dielectrique-plasma dans la zone source du reacteur. Ce phenomene indique une tres nette superiorite du coefficient de diffusion axial par rapport au coefficient de diffusion radial. Notre reacteur a un potentiel interessant pour l'analyse elementaire de materiaux solides puisque le taux de pulverisation y est eleve et que les especes pulverisees sont aisement excitees et ionisees par le plasma.

  14. Plasma properties in high power impulse magnetron sputtering

    OpenAIRE

    Lundin, Daniel

    2008-01-01

    The work presented in this thesis involves experimental and theoretical studies related to plasma properties in high power impulse magnetron sputtering (HiPIMS), and more specifically plasma transport. HiPIMS is an ionized PVD method based on conventional direct current magnetron sputtering (dcMS). In dcMS very little of the sputtered material is ionized since the plasma power density is not high enough. This is not the case for HiPIMS, where a substantial part is ionized, and thus presents m...

  15. Micropower impulse radar technology and applications

    Energy Technology Data Exchange (ETDEWEB)

    Mast, J., LLNL

    1998-04-15

    The LLNL-developed Micropower Impulse Radar (MIR) technology has quickly gone from laboratory concept to embedded circuitry in numerous government and commercial systems in the last few years[l]. The main ideas behind MIR, invented by T. McEwan in the Laser Program, are the generation and detection systems for extremely low- power ultra-wideband pulses in the gigaHertz regime using low-cost components. These ideas, coupled with new antenna systems, timing and radio-frequency (RF) circuitry, computer interfaces, and signal processing, have provided the catalyst for a new generation of compact radar systems. Over the past several years we have concentrated on a number of applications of MIR which address a number of remote-sensing applications relevant to emerging programs in defense, transportation, medical, and environmental research. Some of the past commercial successes have been widely publicized [2] and are only now starting to become available for market. Over 30 patents have been filed and over 15 licenses have been signed on various aspects of the MIR technology. In addition, higher performance systems are under development for specific laboratory programs and government reimbursables. The MIR is an ultra- wideband, range-gated radar system that provides the enabling hardware technology used in the research areas mentioned above. It has numerous performance parameters that can be Selected by careful design to fit the requirements. We have improved the baseline, short- range, MIR system to demonstrate its effectiveness. The radar operates over the hand from approximately I to 4 GHz with pulse repetition frequencies up to 10 MHz. It provides a potential range resolution of I cm at ranges of greater than 20 m. We have developed a suite of algorithms for using MIR for image formation. These algorithms currently support Synthetic aperture and multistate array geometries. This baseline MIR radar imaging system has been used for several programmatic applications.

  16. Measurement of impulse response of force transducers

    Science.gov (United States)

    Fujii, Yusaku

    2001-07-01

    Impulse responses of force transducers are measured. An object levitated with sufficiently small friction using a pneumatic linear bearing is made to collide with a force transducer under test. The inertial force acting on the object is measured as the product of the mass and the acceleration. The acceleration of the object is measured using an optical interferometer. The output signal of the force transducer and the inertial force acting on the levitated object are then compared. Impulses with a maximum value of approximately 80-90 N with a half value width of approximately 5-19 ms have been applied to two different types of force transducers. The inertial force is measured with standard uncertainty of approximately 0.9 N, which corresponds to approximately 1% of the maximum applied impulse.

  17. Impulse holograms in amorphous semiconductor films

    International Nuclear Information System (INIS)

    Impulse hologram recording in amorphous chalcogenide semiconductor films with pulse duration from minutes to picoseconds is considered. Nanosecond pulses are shown to be optimal due to the nonlinearity to films. Millisecond impulse hologram recording is experimentally studied. It is found that about 500 times lower exposure is needed to reach the same diffraction efficiency when compared to CW case. The millisecond recording is non-permanent. A nonlinear photoinduced recharging of localized states in the band gap is found to be responsible for the millisecond recording. It can be applied for non-permanent optical storage and optical information processing. (authors)

  18. [Arson--a disorder of impulse control?].

    Science.gov (United States)

    Hollweg, M

    1994-06-01

    Reviewing the literature the current knowledge about the motivational basis of arson is discussed. Fire-setters form a heterogenous group; they seem to commit their crimes for different reasons. Some of them are imbecile, some suicidal, and other showed autoaggressive behaviour in the past; sometimes a connection with sexual excitement can be observed. The criteria for the diagnosis "pyromania" used in the classification manuals DSM-III-R and ICD-10 are strict, in order to facilitate an operationalised diagnosis. Most of the fire-settings cannot be classified under this subcategory of "disorders of impulse control". However, impairments of impulse control are typical characteristics in most cases of arson. PMID:8061462

  19. Impulse control disorders in Parkinson's disease

    Directory of Open Access Journals (Sweden)

    HAN Xun

    2013-08-01

    Full Text Available Impulse control disorders (ICDs in Parkinson's disease (PD are common with a frequency of 13.61% , which are associated with impaired functioning and with depressive, anxiety and obsessive symptoms, novelty seeking and impulsivity. These behaviors have a bad influence on PD patients in the quality of life. Different behavioral subtypes suggest pathophysiological differences. Recent large scale studies and converging findings are beginning to provide an understanding of mechanisms underlying ICDs in PD which can guide the prevention of these behaviors and optimize therapeutic approaches. This paper will take a review on the recent advances in the epidemiology, risk factors, pathophysiology, diagnosis and therapy of ICDs in PD.

  20. Does drinking refusal self-efficacy mediate the impulsivity-problematic alcohol use relation?

    Science.gov (United States)

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

    2016-02-01

    There is consistent evidence that impulsivity-like traits relate to problematic alcohol involvement; however, identifying mechanisms that account for this relation remains an important area of research. Drinking refusal self-efficacy (or a person's ability to resist alcohol; DRSE) has been shown to predict alcohol use among college students and may be a relevant mediator of the impulsivity-alcohol relation. The current study examined the indirect effect of various constructs related to impulsivity (i.e., urgency, sensation seeking, and deficits in conscientiousness) via several facets of DRSE (i.e., social pressure, opportunistic, and emotional relief) on alcohol-related problems among a large sample of college students (N=891). Overall, results indicated that certain DRSE facets were significant mediators of the relation between impulsivity-related constructs and alcohol problems. More specifically, emotional-relief DRSE was a mediator for the respective relations between urgency and deficits in conscientiousness and alcohol problems, whereas social-DRSE was a significant mediator of the respective relations between urgency and sensation seeking with alcohol problems. Results from this study suggest particular types of DRSE are important mediators of the relations between specific impulsivity constructs and alcohol-related problems. These findings support prevention and intervention efforts that seek to enhance drinking refusal self-efficacy skills of college students, particularly those high in certain personality features, in order to reduce alcohol-related problems among this population. PMID:26547044

  1. Asymptotical p-Moment Stability of Stochastic Impulsive Differential Equations and Its Application in Impulsive Control

    International Nuclear Information System (INIS)

    In this paper, the asymptotical p-moment stability of stochastic impulsive differential equations is studied, and a comparison theory to ensure the asymptotical p-moment stability for trivial solution of this system is established, from which we can find out whether a stochastic impulsive differential system is stable just from a deterministic comparison system. As an application of this theory, we control the chaos of stochastic Chen system using impulsive method, and a stable region is deduced too. Finally, numerical simulations verify the feasibility of our method. (general)

  2. Linear and Nonlinear Coupled Dust-Acoustic and Dust-Drift Waves in a Nonuniform Magnetoplasma with Opposite Polarity Charged Dust Grains

    International Nuclear Information System (INIS)

    Linear and nonlinear properties of ultra low-frequency (in comparison with the dust gyrofrequency), short wavelength (in comparison with the ion gyroradius) coupled dust-acoustic (DA) and dust-drift (DD) waves in a nonuniform dusty magnetoplasma with opposite polarity dust grains are investigated. By using the Boltzmann distribution for electrons and ions, and the hydrodynamic equations for the dust fluid, a set of nonlinear equations is derived. In the linear limit, a dispersion relation is obtained which exhibits coupling between the DA and DD waves. In the nonlinear regime, the nonlinear equations in a stationary frame can be reduced to an inhomogeneous differential equation. The latter yields both a dipolar vortex and a vortex street, depending on the translational speed of the vortices. The results should be useful for understanding the salient features of electrostatic waves and coherent nonlinear structures in Saturn's rings

  3. The Hydraulic Ram (Or Impulse) Pump

    Science.gov (United States)

    Mills, Allan

    2014-01-01

    The hydraulic impulse pump utilizes a fraction of the momentum of a flowing stream to lift a small portion of that water to a higher level. There it may be accumulated in an elevated cistern to provide sufficient water for several families, for the pump works 24 h a day with no additional source of energy. The operation of the pump is described,

  4. Impulse noise trauma during army weapon firing

    OpenAIRE

    Munjal, K. R.; Singh, V.P.

    1997-01-01

    A 100 infanty personnel firing modern weapons such as the Anti Tank Guided Missile, 106mm Recoiless Gun (RCL), 84mm Rocket Launcher (RL) and 81mm Mortar were studied for the effect of impulse noise on the ear and the evolution of the Temporary Threshold Shift (TTS), Recovery Time (RT) and Permanent Threshold Shift (PTS) was traced.

  5. Reflectiveness/Impulsiveness and Mathematics Achievement

    Science.gov (United States)

    Cathcart, W. George; Liedtke, Werner

    1969-01-01

    Report of research to test the hypothesis that reflective students would be higher achievers in mathematics than impulsive pupils. An achievement test was developed to measure understanding of mathematical concepts and applications, ability to solve verbal problems and recall basic facts. Data suggest that reflective students obtain better

  6. Impulse Control of Multidimensional Jump Diffusions

    OpenAIRE

    Mark H A Davis; Guo, Xin; Wu, Guoliang

    2009-01-01

    This paper studies regularity property of the value function for an infinite-horizon discounted cost impulse control problem, where the underlying controlled process is a multidimensional jump diffusion with possibly `infinite-activity' jumps. Surprisingly, despite these jumps, we obtain the same degree of regularity as for the diffusion case, at least when the jump satisfies certain integrability conditions.

  7. Impulse Plasma In Surface Engineering - a review

    International Nuclear Information System (INIS)

    The article describes the view of the plasma surface engineering, assuming the role of non-thermal energy effects in the synthesis of materials and coatings deposition. In the following study it was underlined that the vapor excitation through the application of an electric field during coatings deposition gives new possibilities for coatings formation. As an example the IPD method was chosen. During the IPD (Impulse Plasma Deposition) the impulse plasma is generated in the coaxial accelerator by strong periodic electrical pulses. The impulse plasma is distributed in the form of energetic plasma pockets. Due to the almost completely ionization of gas, the nucleation of new phases takes place on ions directly in the plasma itself. As a result the coatings of metastable materials with nano-amorphous structure and excellent adhesion to the non-heated intentionally substrates could be deposited. Recently the novel way of impulse plasma generation during the coatings deposition was proposed and developed by our group. An efficient tool for plasma process control, the plasma forming gas injection to the interelectrode space was used. Periodic changing the gas pressure results in increasing both the degree of dispersion and the dynamics of the plasma pulses. The advantage of the new technique in deposition of coatings with exceptionally good properties has been demonstrated in the industrial scale not only in the case of the IPD method but also in the case of very well known magnetron sputtering method

  8. A Model-based Analysis of Impulsivity Using a Slot-Machine Gambling Paradigm

    Directory of Open Access Journals (Sweden)

    Saee Paliwal

    2014-07-01

    Full Text Available Impulsivity plays a key role in decision-making under uncertainty. It is a significant contributor to problem and pathological gambling. Standard assessments of impulsivity by questionnaires, however, have various limitations, partly because impulsivity is a broad, multi-faceted concept. What remains unclear is which of these facets contribute to shaping gambling behavior. In the present study, we investigated impulsivity as expressed in a gambling setting by applying computational modeling to data from 47 healthy male volunteers who played a realistic, virtual slot-machine gambling task. Behaviorally, we found that impulsivity, as measured independently by the 11th revision of the Barratt Impulsiveness Scale (BIS-11, correlated significantly with an aggregate read-out of the following gambling responses: bet increases, machines switches, casino switches and double-ups. Using model comparison, we compared a set of hierarchical Bayesian belief-updating models, i.e. the Hierarchical Gaussian Filter (HGF and Rescorla-Wagner reinforcement learning models, with regard to how well they explained different aspects of the behavioral data. We then examined the construct validity of our winning models with multiple regression, relating subject-specific model parameter estimates to the individual BIS-11 total scores. In the most predictive model (a three-level HGF, the two free parameters encoded uncertainty-dependent mechanisms of belief updates and significantly explained BIS-11 variance across subjects. Furthermore, in this model, decision noise was a function of trial-wise uncertainty about winning probability. Collectively, our results provide a proof of concept that hierarchical Bayesian models can characterize the decision-making mechanisms linked to impulsivity. These novel indices of gambling mechanisms unmasked during actual play may be useful for online prevention measures for at-risk players and future assessments of pathological gambling.

  9. Objects, decision considerations and self-image in men's and women's impulse purchases.

    Science.gov (United States)

    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. PMID:8826795

  10. Recent Translational Findings on Impulsivity in Relation to Drug Abuse

    OpenAIRE

    Weafer, Jessica; Mitchell, Suzanne H.; de Wit, Harriet

    2014-01-01

    Impulsive behavior is strongly implicated in drug abuse, as both a cause and a consequence of drug use. To understand how impulsive behaviors lead to and result from drug use, translational evidence from both human and non-human animal studies is needed. Here, we review recent (2009 or later) studies that have investigated two major components of impulsive behavior, inhibitory control and impulsive choice, across preclinical and clinical studies. We concentrate on the stop-signal task as the ...

  11. ADHD-hyperactive/impulsive subtype in adults

    Directory of Open Access Journals (Sweden)

    Stephen V. Faraone

    2010-01-01

    Full Text Available This is the first study to evaluate ADHD-hyperactive/impulsive subtype in a large clinical sample of adults with ADHD. The Quality of Life, Effectiveness, Safety and Tolerability (QuEST study included 725 adults who received clinician diagnoses of any ADHD subtype. Cross-sectional baseline data from 691 patients diagnosed with the hyperactive/impulsive (HI, inattentive (IA and combined subtypes were used to compare the groups on the clinician administered ADHD-RS, clinical features and health-related quality of life. A consistent pattern of differences was found between the ADHD-I and combined subtypes, with the combined subtype being more likely to be diagnosed in childhood, more severe symptom severity and lower HRQL. Twenty-three patients out of the total sample of 691 patients (3% received a clinician diagnosis of ADHD - hyperactive/impulsive subtype. Review of the ratings on the ADHD-RS-IV demonstrated, however, that this group had ratings of inattention comparable to the inattentive group. There were no significant differences found between the ADHD-HI and the other subtypes in symptom severity, functioning or quality of life. The hyperactive/impulsive subtype group identified by clinicians in this study was not significantly different from the rest of the sample. By contrast, significant differences were found between the inattentive and combined types. This suggests that in adults, hyperactivity declines and inattention remains significant, making the hyperactive/impulsive subtype as defined by childhood criteria a very rare condition and raising questions as to the validity of the HI subtype in adults.

  12. Analysis of Caputo impulsive fractional order differential equations with applications

    CERN Document Server

    Mahto, Lakshman; Favini, Angelo

    2012-01-01

    We use Sadavoskii's fixed point method to investigate the existence and uniqueness of solutions of Caputo impulsive fractional differential equations of order \\alpha between 0 and 1 with one example of impulsive logistic model and few other examples as well. We also discuss Caputo impulsive fractional differential equations with finite delay. The results proven are new and complement the existing one.

  13. Temperament and Character Dimensions: Correlates of Impulsivity in Morphine Addicts

    OpenAIRE

    Abassi; Abolghasemi

    2015-01-01

    Background Given the role of temperament and character dimensions on impulsivity in addicts, the purpose of this study was to temperament and character dimensions: correlates of impulsivity in morphine addicts. Objectives The aim of this study was to determine and verify the association of temperament and character dimensions with impulsivity in morphine addicts. Patients and Methods ...

  14. H∞ Control of Fuzzy Impulsive Systems with Quantized Feedback

    Directory of Open Access Journals (Sweden)

    Yingqi Zhang

    2009-07-01

    Full Text Available This paper is concerned with the problem of H∞ control of fuzzy nonlinear impulsive systems with quantized feedback. New results on the H∞ feedback control are established for one class of fuzzy nonlinear uncertain impulsive systems and one class of fuzzy nonlinear impulsive systems with nonlinear uncertainties by choosing appropriately quantized strategies and applying Lyapunov function approach, respectively.

  15. On some impulsive fractional differential equations in Banach spaces

    Directory of Open Access Journals (Sweden)

    JinRong Wang

    2010-01-01

    Full Text Available This paper deals with some impulsive fractional differential equations in Banach spaces. Utilizing the Leray-Schauder fixed point theorem and the impulsive nonlinear singular version of the Gronwall inequality, the existence of \\(PC\\-mild solutions for some fractional differential equations with impulses are obtained under some easily checked conditions. At last, an example is given for demonstration.

  16. Nonlinear impulsive Volterra integral equations in Banach spaces and applications

    OpenAIRE

    Dajun Guo

    1993-01-01

    In this paper, we first extend results on the existence of maximal solutions for nonlinear Volterra integral equations in Banach spaces to impulsive Volterra integral equations. Then, we give some applications to initial value problems for first order impulsive differential equations in Banach spaces. The results are demonstrated by means of an example of an infinite system for impulsive differential equations.

  17. Dwell-time conditions for robust stability of impulsive systems

    OpenAIRE

    Dashkovskiy, Sergey; Mironchenko, Andrii

    2012-01-01

    We prove that impulsive systems, which possess an ISS Lyapunov function, are ISS for impulse time sequences, which satisfy the fixed dwell-time condition. If the ISS Lyapunov function is the exponential one, we provide stronger result, which guarantees uniform ISS of the whole system over sequences of impulse times, which satisfy the generalized average dwell-time condition.

  18. Adaptive-impulsive synchronization of uncertain complex dynamical networks

    International Nuclear Information System (INIS)

    This Letter studies adaptive-impulsive synchronization of uncertain complex dynamical networks. Based on the stability analysis of impulsive system, several network synchronization criteria for local and global adaptive-impulsive synchronization are established. Numerical example is also given to illustrate the results

  19. Hyperactive-Impulsive Symptoms Associated with Self-Reported Sleep Quality in Nonmedicated Adults with ADHD

    Science.gov (United States)

    Mahajan, Neha; Hong, Nuong; Wigal, Timothy L.; Gehricke, Jean-G.

    2010-01-01

    Objective: Individuals with ADHD often report sleep problems. Though most studies on ADHD and sleep examined children or nonclinically diagnosed adults, the present study specifically examines nonmedicated adults with ADHD to determine whether inattentive and hyperactive-impulsive symptoms are associated with sleep problems. Method: A total of 22

  20. Unique Contributions of Impulsivity and Inhibition to Prereading Skills in Preschoolers at Head Start

    Science.gov (United States)

    Fuhs, Mary Wagner; Wyant, Autumn B.; Day, Jeanne D.

    2011-01-01

    The goal of this study was to explore the relationship between temperament (specifically impulsivity and inhibition) and prereading skills (letter knowledge and print concepts) in preschool children from disadvantaged backgrounds. The participants in the study were 111 preschool children with a mean age of 58.09 months (SD = 5.80) attending Head

  1. Non-smooth Approach for Contact Dynamics and Impulse-based Control of Frictional Furuta Pendulum

    CERN Document Server

    Zhang, Hantian

    2014-01-01

    In this thesis, a non-penetrated and physically consistent non-smooth numerical approach has been proposed, by employing the Prox formulation and Moreau's mid-point time-stepping rule, for the contact dynamics with coupled and decoupled constraints. Under this circumstance, the robust impulse-based control has been successfully implemented and validated on the motion system of controlled frictional oscillator. Further improvement has been achieved by utilizing shooting method in the impulse estimating process instead of robust estimation. This non-smooth numerical technique has been applied to the under-actuated friction-coupled mulit-body system, by means of an implementation on the controlled frictional Furuta pendulum. The specifically designed impulse-based controller has successfully solved the problem of stabilization of the inverted frictional Furuta pendulum, which is suffered from the stiction effect of friction.

  2. The Stomach-Derived Hormone Ghrelin Increases Impulsive Behavior.

    Science.gov (United States)

    Anderberg, Rozita H; Hansson, Caroline; Fenander, Maya; Richard, Jennifer E; Dickson, Suzanne L; Nissbrandt, Hans; Bergquist, Filip; Skibicka, Karolina P

    2016-04-01

    Impulsivity, defined as impaired decision making, is associated with many psychiatric and behavioral disorders, such as attention-deficit/hyperactivity disorder as well as eating disorders. Recent data indicate that there is a strong positive correlation between food reward behavior and impulsivity, but the mechanisms behind this relationship remain unknown. Here we hypothesize that ghrelin, an orexigenic hormone produced by the stomach and known to increase food reward behavior, also increases impulsivity. In order to assess the impact of ghrelin on impulsivity, rats were trained in three complementary tests of impulsive behavior and choice: differential reinforcement of low rate (DRL), go/no-go, and delay discounting. Ghrelin injection into the lateral ventricle increased impulsive behavior, as indicated by reduced efficiency of performance in the DRL test, and increased lever pressing during the no-go periods of the go/no-go test. Central ghrelin stimulation also increased impulsive choice, as evidenced by the reduced choice for large rewards when delivered with a delay in the delay discounting test. In order to determine whether signaling at the central ghrelin receptors is necessary for maintenance of normal levels of impulsive behavior, DRL performance was assessed following ghrelin receptor blockade with central infusion of a ghrelin receptor antagonist. Central ghrelin receptor blockade reduced impulsive behavior, as reflected by increased efficiency of performance in the DRL task. To further investigate the neurobiological substrate underlying the impulsivity effect of ghrelin, we microinjected ghrelin into the ventral tegmental area, an area harboring dopaminergic cell bodies. Ghrelin receptor stimulation within the VTA was sufficient to increase impulsive behavior. We further evaluated the impact of ghrelin on dopamine-related gene expression and dopamine turnover in brain areas key in impulsive behavior control. This study provides the first demonstration that the stomach-produced hormone ghrelin increases impulsivity and also indicates that ghrelin can change two major components of impulsivity-motor and choice impulsivity. PMID:26424164

  3. Impulsive Aggression as a Comorbidity of Attention-Deficit/Hyperactivity Disorder in Children and Adolescents

    Science.gov (United States)

    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 aggressive behaviors do not remit with primary ADHD therapy, empirical evidence does not currently support the use of any specific agent. Randomized controlled trials are needed to identify aggression-targeted agents with favorable benefit–risk profiles. PMID:26744906

  4. High impulsivity predicting vulnerability to cocaine addiction in rats

    DEFF Research Database (Denmark)

    Molander, Anna C; Mar, Adam; Norbury, Agnes; Steventon, Sarah; Moreno, Margarita; Caprioli, Daniele; Theobald, David E H; Belin, David; Everitt, Barry J; Robbins, Trevor W; Dalley, Jeffrey W

    2011-01-01

    RATIONALE: Impulsivity is a vulnerability marker for drug addiction in which other behavioural traits such as anxiety and novelty seeking ('sensation seeking') are also widely present. However, inter-relationships between impulsivity, novelty seeking and anxiety traits are poorly understood...... increasing or decreasing impulsivity in SHI and SLI rats, did reduce the contrast in impulsivity between these two groups of animals. CONCLUSIONS: This investigation indicates that behavioural impulsivity in rats on the 5-CSRTT, which predicts vulnerability for cocaine addiction, is distinct from anxiety......, novelty reactivity and novelty-induced stress responses, and thus has relevance for the aetiology of drug addiction....

  5. High impulsivity predicting vulnerability to cocaine addiction in rats

    DEFF Research Database (Denmark)

    Molander, Anna C; Mar, Adam; Norbury, Agnes; Steventon, Sarah; Moreno, Margarita; Caprioli, Daniele; Theobald, David E H; Belin, David; Everitt, Barry J; Robbins, Trevor W; Dalley, Jeffrey W

    2011-01-01

    RATIONALE: Impulsivity is a vulnerability marker for drug addiction in which other behavioural traits such as anxiety and novelty seeking ('sensation seeking') are also widely present. However, inter-relationships between impulsivity, novelty seeking and anxiety traits are poorly understood...... increasing or decreasing impulsivity in SHI and SLI rats, did reduce the contrast in impulsivity between these two groups of animals. CONCLUSIONS: This investigation indicates that behavioural impulsivity in rats on the 5-CSRTT, which predicts vulnerability for cocaine addiction, is distinct from anxiety...

  6. Stability and Stabilization of Impulsive Stochastic Delay Difference Equations

    Directory of Open Access Journals (Sweden)

    Liming Wang

    2010-01-01

    Full Text Available When an impulsive control is adopted for a stochastic delay difference system (SDDS, there are at least two situations that should be contemplated. If the SDDS is stable, then what kind of impulse can the original system tolerate to keep stable? If the SDDS is unstable, then what kind of impulsive strategy should be taken to make the system stable? Using the Lyapunov-Razumikhin technique, we establish criteria for the stability of impulsive stochastic delay difference equations and these criteria answer those questions. As for applications, we consider a kind of impulsive stochastic delay difference equation and present some corollaries to our main results.

  7. Impulsive control of nonlinear systems with time-varying delays

    International Nuclear Information System (INIS)

    A whole impulsive control scheme of nonlinear systems with time-varying delays, which is an extension for impulsive control of nonlinear systems without time delay, is presented in this paper. Utilizing the Lyapunov functions and the impulsive-type comparison principles, we establish a series of different conditions under which impulsively controlled nonlinear systems with time-varying delays are asymptotically stable. Then we estimate upper bounds of impulse interval and time-varying delays for asymptotically stable control. Finally a numerical example is given to illustrate the effectiveness of the method. (general)

  8. Alexithymia as a Mediator Between Childhood Maltreatment and Impulsivity.

    Science.gov (United States)

    Gaher, Raluca M; Arens, Ashley M; Shishido, Hanako

    2015-10-01

    Impulsivity, specifically negative urgency, is associated with diverse health risk behaviours, yet relatively little research has examined factors contributing to negative urgency. The purpose of this study was to examine the relationship between childhood maltreatment, alexithymia and negative urgency. The sample was comprised of 410 undergraduate students who completed measures online. A series of regression analyses tested whether alexithymia mediated the association between childhood maltreatment and negative urgency. Results supported the hypothesized mediation model. Subsequent analyses examined effects of specific subtypes of maltreatment and alexithymia subscales. These analyses indicated that growing up in a punishing environment (e.g. being hit or beat; expected to follow a strict code of behaviour) was indirectly associated with negative urgency via difficulty identifying feelings, suggesting that excessive use of punishment during childhood may reduce the development of the ability to identify and label feeling states. This difficulty in emotional processing may in turn lead to acting rashly when emotionally aroused. PMID:26468625

  9. State Estimation for the VASIMR Plasma Engine

    OpenAIRE

    Lynn, Shane; Ringwood, John; Del Valle Gamboa, Juan Ignacio

    2008-01-01

    This paper presents work on the application of virtual metrology techniques to the VAriable Specific Impulse Magnetoplasma Rocket (VASMIR) engine. The work concentrates on the estimation of internal temperatures of the rocket using state space models and Optical Emission Spectroscopy (OES). These estimations are useful as direct thermal measurements will not be available in the final system design.

  10. Impulsive action and impulsive choice across substance and behavioral addictions: cause or consequence?

    Science.gov (United States)

    Grant, Jon E; Chamberlain, Samuel R

    2014-11-01

    Substance use disorders are prevalent and debilitating. Certain behavioral syndromes ('behavioral addictions') characterized by repetitive habits, such as gambling disorder, stealing, shopping, and compulsive internet use, may share clinical, co-morbid, and neurobiological parallels with substance addictions. This review considers overlap between substance and behavioral addictions with a particular focus on impulsive action (inability to inhibit motor responses), and impulsive choice (preference for immediate smaller rewards to the detriment of long-term outcomes). We find that acute consumption of drugs with abuse potential is capable of modulating impulsive choice and action, although magnitude and direction of effect appear contingent on baseline function. Many lines of evidence, including findings from meta-analyses, show an association between chronic drug use and elevated impulsive choice and action. In some instances, elevated impulsive choice and action have been found to predate the development of substance use disorders, perhaps signifying their candidacy as objective vulnerability markers. Research in behavioral addictions is preliminary, and has mostly focused on impulsive action, finding this to be elevated versus controls, similar to that seen in chronic substance use disorders. Only a handful of imaging studies has explored the neural correlates of impulsive action and choice across these disorders. Key areas for future research are highlighted along with potential implications in terms of neurobiological models and treatment. In particular, future work should further explore whether the cognitive deficits identified are state or trait in nature: i.e. are evident before addiction perhaps signaling risk; or are a consequence of repetitive engagement in habitual behavior; and effects of novel agents known to modulate these cognitive abilities on various addictive disorders. PMID:24864028

  11. Narcissism predicts impulsive buying: phenotypic and genetic evidence

    Science.gov (United States)

    Cai, Huajian; Shi, Yuanyuan; Fang, Xiang; Luo, Yu L. L.

    2015-01-01

    Impulsive buying makes billions of dollars for retail businesses every year, particularly in an era of thriving e-commerce. Narcissism, characterized by impulsivity and materialism, may serve as a potential antecedent to impulsive buying. To test this hypothesis, two studies examined the relationship between narcissism and impulsive buying. In Study 1, we surveyed an online sample and found that while adaptive narcissism was not correlated with impulsive buying, maladaptive narcissism was significantly predictive of the impulsive buying tendency. By investigating 304 twin pairs, Study 2 showed that global narcissism and its two components, adaptive and maladaptive narcissism, as well as the impulsive buying tendency were heritable. The study found, moreover, that the connections between global narcissism and impulsive buying, and between maladaptive narcissism and impulsive buying were genetically based. These findings not only establish a link between narcissism and impulsive buying but also help to identify the origins of the link. The present studies deepen our understanding of narcissism, impulsive buying, and their interrelationship. PMID:26217251

  12. Narcissism predicts impulsive buying: phenotypic and genetic evidence.

    Science.gov (United States)

    Cai, Huajian; Shi, Yuanyuan; Fang, Xiang; Luo, Yu L L

    2015-01-01

    Impulsive buying makes billions of dollars for retail businesses every year, particularly in an era of thriving e-commerce. Narcissism, characterized by impulsivity and materialism, may serve as a potential antecedent to impulsive buying. To test this hypothesis, two studies examined the relationship between narcissism and impulsive buying. In Study 1, we surveyed an online sample and found that while adaptive narcissism was not correlated with impulsive buying, maladaptive narcissism was significantly predictive of the impulsive buying tendency. By investigating 304 twin pairs, Study 2 showed that global narcissism and its two components, adaptive and maladaptive narcissism, as well as the impulsive buying tendency were heritable. The study found, moreover, that the connections between global narcissism and impulsive buying, and between maladaptive narcissism and impulsive buying were genetically based. These findings not only establish a link between narcissism and impulsive buying but also help to identify the origins of the link. The present studies deepen our understanding of narcissism, impulsive buying, and their interrelationship. PMID:26217251

  13. Single-photon emission tomography imaging of monoamine transporters in impulsive violent behaviour

    International Nuclear Information System (INIS)

    Several studies have shown that impulsive violent and suicidal behaviour is associated with a central serotonin deficit, but until now it has not been possible to use laboratory tests with high sensitivity and specificity to study this kind of deficit or to localize the sites of serotonergic abnormalities in the living human brain. The aim of this study was to test the hypothesis that monoamine transporter density in brain is decreased in subjects with impulsive violent behaviour. We studied serotonin (5-HT) and dopamine (DA) transporter specific binding in 52 subjects (21 impulsive violent offenders, 21 age- and sex-matched healthy controls, and ten non-violent alcoholic controls) with single-photon emission tomography (SPET) using iodine-123-labelled 2β-carbomethoxy-3β(4-iodophenyl)tropane ([123I]β-CIT) as the tracer. The blind quantitative analysis revealed that the 5-HT specific binding of [123I]β-CIT in the midbrain of violent offenders was lower than that in the healthy control subjects (P<0.005; t test) or the non-violent alcoholics (P<0.05). The results imply that habitual impulsive aggressive behaviour in man is associated with a decrease in the 5-HT transporter density. (orig.)

  14. Morphometric correlation of impulsivity in medial prefrontal cortex.

    Science.gov (United States)

    Cho, Sang Soo; Pellecchia, Giovanna; Aminian, Kelly; Ray, Nicola; Segura, Barbara; Obeso, Ignacio; Strafella, Antonio P

    2013-07-01

    Impulsivity is a complex behaviour composed of different domains encompassing behavioural dis-inhibition, risky decision-making and delay discounting abnormalities. To investigate regional brain correlates between levels of individual impulsivity and grey matter volume, we performed voxel-based morphometric correlation analysis in 34 young, healthy subjects using impulsivity scores measured with Barratt Impulsivity Scale-11 and computerized Kirby's delay discounting task. The VBM analysis showed that impulsivity appears to be reliant on a network of cortical (medial prefrontal cortex and dorsolateral prefrontal cortex) and subcortical (ventral striatum) structures emphasizing the importance of brain networks associated with reward related decision-making in daily life as morphological biomarkers for impulsivity in a normal healthy population. While our results in healthy volunteers may not directly extend to pathological conditions, they provide an insight into the mechanisms of impulsive behaviour in patients with abnormalities in prefrontal/frontal-striatal connections, such as in drug abuse, pathological gambling, ADHD and Parkinson's disease. PMID:23274773

  15. Impact of Impulse Stops on Pedestrian Flow

    CERN Document Server

    Kwak, Jaeyoung; Luttinen, Tapio; Kosonen, Iisakki

    2015-01-01

    We numerically study the impact of impulse stops on pedestrian flow for a straight corridor with multiple attractions. The impulse stop is simulated by the switching behavior model, a function of the social influence strength and the number of attendees near the attraction. When the pedestrian influx is low, one can observe a stable flow where attendees make a complete stop at an attraction and then leave the attraction after a certain amount of time. When the pedestrian influx is high, an unstable flow is observed for strong social influence. In the unstable flow, attendees near the attraction are crowded out from the clusters by others due to the interpersonal repulsion. The expelled pedestrians impede the pedestrian traffic between the left and right boundaries of the corridor. These collective patterns of pedestrian flow are summarized in a schematic phase diagram.

  16. Coherent Jitter in Impulse Radio Tomography

    Science.gov (United States)

    Shipilov, S. .; Yakubov, V. P.; Satarov, R. N.

    2016-01-01

    A new method of increasing resolution of radio images due to nonlinear ultra-wideband data processing without any modification of the employed hardware is presented. The approach is applicable for stroboscopic filling of ultrashort impulses in which the error of triggering of a sensing impulse generator - a jitter - detected as noise in the gated data - is always presented. The nonlinear operation of selection of the coherent noise component in combination with the synthetic aperture radar (SAR) method provides a higher contrast of the radio image in comparison with operation of jitter smoothing. As a result, the physical effect of jitter occurrence that is typically negative yields a positive result. Examples of experimental data processing confirm this conclusion.

  17. Cigarette cravings, impulsivity and the brain

    Directory of Open Access Journals (Sweden)

    Stphane Potvin

    2015-09-01

    Full Text Available Craving is a core feature of tobacco use disorder as well as a significant predictor of smoking relapse. Studies have shown that appetitive smoking-related stimuli (e.g. someone smoking trigger significant cravings in smokers which impedes their self-control capacities and promotes drug seeking behavior. In this review, we begin by an overview of functional magnetic resonance imaging (fMRI studies investigating the neural correlates of smokers to appetitive smoking cues. The literature reveals a complex and vastly distributed neuronal network underlying smokers craving response that recruits regions involved in self-referential processing, panning/regulatory processes, emotional responding, attentional biases, and automatic conducts. We then selectively review important factors contributing to the heterogeneity of results that significantly limit the implications of these findings, namely between- (abstinence, smoking expectancies and self-regulation and within-studies factors (severity of smoking dependence, sex-differences, motivation to quit and genetic factors. Remarkably, we found that little to no attention has been devoted to examine the influence of personality traits on the neural correlates of cigarette cravings in fMRI studies. Impulsivity has been linked with craving and relapse in substance and tobacco use, which prompted our research team to examine the influence of impulsivity on cigarette cravings in an fMRI study. We found that the influence of impulsivity on cigarette cravings was mediated by fronto-cingular mechanisms. Given the high prevalence of cigarette smoking in several psychiatric disorders that are characterized by significant levels of impulsivity, we conclude by identifying psychiatric patients as a target population whose tobacco smoking habits deserve further behavioral and neuro-imaging investigation.

  18. Modeling High Power Impulse Magnetron Sputtering Discharges

    OpenAIRE

    Huo, Chunqing

    2012-01-01

    HiPIMS, high power impulse magnetron sputtering, is a promising technology that has attracted a lot of attention ever since its appearance. A time-dependent plasma discharge model has been developed for the ionization region in HiPIMS discharges. As a flexible modeling tool, it can be used to explore the temporal variations of the ionized fractions of the working gas and the sputtered vapor, the electron density and temperature, and the gas rarefaction and refill processes. The model developm...

  19. Fundamentals of High Power Impulse Magnetron Sputtering

    OpenAIRE

    Böhlmark, Johan

    2006-01-01

    In plasma assisted thin film growth, control over the energy and direction of the incoming species is desired. If the growth species are ionized this can be achieved by the use of a substrate bias or a magnetic field. Ions may be accelerated by an applied potential, whereas neutral particles may not. Thin films grown by ionized physical vapor deposition (I-PVD) have lately shown promising results regarding film structure and adhesion. High power impulse magnetron sputtering (HIPIMS) is a rela...

  20. Dynamic Properties of Impulse Measuring Systems

    DEFF Research Database (Denmark)

    Pedersen, A.; Lausen, P.

    1971-01-01

    After some basic considerations the dynamic properties of the measuring system are subjected to a general examination based on a number of responses, characteristic of the system. It is demonstrated that an impulse circuit has an internal impedance different from zero, for which reason the...... interaction between the generator and the measuring circuit is of paramount importance to the voltage across the test object. Based on the measured values the determination of the applied voltage is considered....

  1. FEM Analysis of Turgo Impulse Turbine Blade

    OpenAIRE

    Sourabh KHURANA; Goel, Varun; Kumar, Anoop

    2013-01-01

    The present research work describes the development of Turgo turbine blades on the Solidworks software. Finite element simulation (Ansys V14) has been used for analysis of stress and total deformation produced inside the Turgo impulse turbine. Finite element simulation is effective when it is used to analyze the strain and stress distribution. It has been observed during analysis that the maximum stress occurs at the root of blade suction side.

  2. FEM Analysis of Turgo Impulse Turbine Blade

    Directory of Open Access Journals (Sweden)

    Sourabh KHURANA

    2013-07-01

    Full Text Available The present research work describes the development of Turgo turbine blades on the Solidworks software. Finite element simulation (Ansys V14 has been used for analysis of stress and total deformation produced inside the Turgo impulse turbine. Finite element simulation is effective when it is used to analyze the strain and stress distribution. It has been observed during analysis that the maximum stress occurs at the root of blade suction side.

  3. Impulsivity, Peer Influence, and Adolescent Substance Use

    OpenAIRE

    Stautz, Kaidy

    2013-01-01

    Individuals in Western societies commonly begin to experiment with alcohol and/or cannabis during their adolescent years. Many experience negative consequences from the use of these substances and a minority develop pathological problems such as abuse and dependence. Previous research has identified myriad individual and environmental variables that precede and predict problematic substance use. Two such risk factors are the personality trait impulsivity and the influence of substance-using p...

  4. The Hydraulic Ram (Or Impulse) Pump

    Science.gov (United States)

    Mills, Allan

    2014-01-01

    The hydraulic impulse pump utilizes a fraction of the momentum of a flowing stream to lift a small portion of that water to a higher level. There it may be accumulated in an elevated cistern to provide sufficient water for several families, for the pump works 24 h a day with no additional source of energy. The operation of the pump is described,…

  5. Impulse Control of Proportional Reinsurance with Constraints

    OpenAIRE

    Hui Meng; Tak Kuen Siu

    2011-01-01

    We consider an insurance company whose surplus follows a diffusion process with proportional reinsurance and impulse dividend control. Our objective is to maximize expected discounted dividend payouts to shareholders of the company until the time of bankruptcy. To meet some essential requirements of solvency control (e.g., bankruptcy not soon), we impose some constraints on the insurance company's dividend policy. Under two types of constraints, we derive the value functions and optimal contr...

  6. Vacuum fluctuations for spherical gravitational impulsive waves

    OpenAIRE

    Hortaçsu, M.

    1998-01-01

    We propose a method for calculating vacuum fluctuations on the background of a spherical impulsive gravitational wave which results in a finite expression for the vacuum expectation value of the stress-energy tensor. The method is based on first including a cosmological constant as an auxiliary constant. We show that the result for the vacuum expectation value of the stress-energy tensor in second-order perturbation theory is finite if both the cosmological constant and the infrared parameter...

  7. Strength measurement of impulse compacted moulding sand

    OpenAIRE

    T. Mikulczyński; S. Ciskowski

    2011-01-01

    Analysis of impulse compaction process shows that during compaction process moulding sand is subject to deformation and changes oftotal pressure, measured inside compacted moulding sand, represent fading sinusoid. Measured pressure values in stationary states (aftercompaction process) are equal to the sum of squeezing pressure pc and the pressure resulting from compacting the sandmix pu, whichexpresses the obtained strength. Therefore experimental research of moulding sands were conducted. St...

  8. Development of the relativistic impulse approximation

    International Nuclear Information System (INIS)

    This talk contains three parts. Part I reviews the developments which led to the relativistic impulse approximation for proton-nucleus scattering. In Part II, problems with the impulse approximation in its original form - principally the low energy problem - are discussed and traced to pionic contributions. Use of pseudovector covariants in place of pseudoscalar ones in the NN amplitude provides more satisfactory low energy results, however, the difference between pseudovector and pseudoscalar results is ambiguous in the sense that it is not controlled by NN data. Only with further theoretical input can the ambiguity be removed. Part III of the talk presents a new development of the relativistic impulse approximation which is the result of work done in the past year and a half in collaboration with J.A. Tjon. A complete NN amplitude representation is developed and a complete set of Lorentz invariant amplitudes are calculated based on a one-meson exchange model and appropriate integral equations. A meson theoretical basis for the important pair contributions to proton-nucleus scattering is established by the new developments. 28 references

  9. Theory of 'crotchet' impulse component generation

    International Nuclear Information System (INIS)

    It is known that increasing of the electromagnetic emissions flux during the solar flares is accompanied by sudden disturbance of the geomagnetic field, which manifests itself on the ground magnetograms as a 'crotchet'. This disturbance can be understood as a geomagnetic field response to a current intensification in the global ionosphere system due to the conductivity growing. Investigations for the past few years have showed that a temporal structure of the 'crotchet' at solar flares, characterized by harder spectra (presence of a gamma rays), is more complicated and, in reality, is the mixture of the two components: a classic or gradual component and an impulse one. It has been suggested that such impulse disturbance be called 'crotchet' impulse component (CIC). The possible generation mechanism of CIC is the main concern of this paper. According to the mechanism to be discussed, CIC is a geomagnetic field reaction to the changes in the global atmosphere-ionosphere current system related to the stratosphere absorption of solar flare gamma rays (0.1-10 MeV). In this energy band, the most important role the gamma rays absorption plays is the Compton scattering, providing favourable conditions for the vertical transfer of the Compton electrons being produced. The presence of this vertical electric current changes the parameters of the global ionosphere current system and causes the suitable geomagnetic field effect - the CIC event. The theoretical estimates demonstrate good agreement with the characteristics of the CIC event observed on the ground magnetograms. (author)

  10. Impulse approximation versus elementary particle method

    International Nuclear Information System (INIS)

    Calculations are made for radiative muon capture in 3He, both in impulse approximation and with the elementary particle method, and results are compared. It is argued that a diagrammatic method which takes a selected set of Feynman diagrams into account only provides insufficient warrant that effects not included are small. Therefore low-energy theorems are employed, as first given by Adler and Dothan, to determine the amplitude up to and including all terms linear in photon momentum and momentum transfer at the weak vertex. This amplitude is applied to radiative muon capture with the elementary particle method (EPM). The various form factors needed are discussed. It is shown that the results are particularly sensitive to the π-3He-3H coupling constant of which many contradictory determinations have been described in the literature. The classification of the nuclear wave function employed in the impulse approximation (IA) is summarized. The ν-decay of 3H and (radiative muon capture in 3He is treated and numerical results are given. Next, pion photoproduction and radiative pion capture are considered. IA and EPM for radiative muon capture are compared more closely. It is concluded that two-step processes are inherently difficult; the elementary particle method has convergence problems, and unknown parameters are present. In the impulse approximation, which is perhaps conceptually more difficult, the two-step interaction for the nucleon is considered as effectively point-like with small non-local corrections. (Auth.)

  11. Effect of Management of Patients with Anorexia and Bulimia nervosa on Symptoms and Impulsive Behavior

    OpenAIRE

    Sernec, Karin; Tomori, Martina; Zalar, Bojan

    2010-01-01

    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-purgat...

  12. Initial experience of acoustic radiation force impulse ultrasound imaging of cervical lymph nodes

    International Nuclear Information System (INIS)

    The aim of this study was to evaluate acoustic radiation force impulse imaging for cervical lymphadenopathy in routine clinical practice and to correlate the acoustic radiation force impulse values with the morphological signs and the pathological results, which were used as the reference standard. The virtual touch tissue quantification values were analyzed in 123 patients (mean age 40.8 years, range 181 years) with 181 cervical lymph nodes (87 benign, 94 malignant). The diagnostic performance of acoustic radiation force impulse values were evaluated with respect to sensitivity, specificity, and area under the curve using a receiver operating characteristic curve analysis. The mean virtual touch tissue quantification values of the benign lesions (2.01 0.95 m/s) differed from that of the malignant lesions (4.61 2.56 m/s; P < 0.001). The cutoff level for virtual touch tissue quantification value for malignancy was estimated to be 2.595 m/s. Using the receiver operating characteristic curve curves with the cutoff value, the virtual touch tissue quantification value predicted malignancy with a sensitivity of 82.9%, specificity of 93.1% and gave an areas under the curve of 0.906 (95% CI 0.8570.954). Acoustic radiation force impulse is feasible for cervical lymph nodes and provides quantitative elasticity measurements, which may complement B-mode ultrasound and potentially improve the characterization of cervical lymph nodes

  13. Methodology for Calculation of Pressure Impulse Distribution at Gas-Impulse Regeneration of Water Well Filters

    Directory of Open Access Journals (Sweden)

    V. V. Ivashechkin

    2014-07-01

    Full Text Available The paper considers a mathematical model for process of pressure impulse distribution in a water well which appear as a result of underwater gas explosions in cylindrical and spherical explosive chambers with elastic shells and in a rigid cylindrical chamber which is open from the bottom. The proposed calculation methodology developed on the basis of the mathematical model makes it possible to determine pressure in the impulse on a filter wall and at any point of a water well pre-filter zone. 

  14. Synthesis of Room Impulse Responses for Variable Source Characteristics

    Directory of Open Access Journals (Sweden)

    M. Kunkemoeller

    2011-01-01

    Full Text Available Every acoustic source, e.g. a speaker, a musical instrument or a loudspeaker, generally has a frequency dependent characteristic radiation pattern, which is preeminent at higher frequencies. Room acoustic measurements nowadays only account for omnidirectional source characteristics. This motivates a measurement method that is capable of obtaining room impulse responses for these specific radiation patterns by using a superposition approach of several measurements with technically well-defined sound sources. We propose a method based on measurements with a 12-channel independentlydriven dodecahedron loudspeaker array rotated by an automatically controlled turntable.Radiation patterns can be efficiently described with the use of spherical harmonics representation. We propose a method that uses this representation for the spherical loudspeaker array used for the measurements and the target radiation pattern to be used for the synthesis.We show validating results for a deterministic test sound source inside in a small lecture hall.

  15. Study of impulse control disorders among women presenting nicotine dependence.

    Science.gov (United States)

    Lejoyeux, Michel; Kerner, Laurent; Thauvin, Isabelle; Loi, Sabrina

    2006-01-01

    Objective. Impulse control disorders (ICDs) include intermittent explosive disorder, kleptomania, trichotillomania, pyromania and pathological gambling. Several studies have showed an association between ICDs and alcohol use disorders. The rate of co-occurrence ICDs and nicotine dependence has never been investigated. We thus assessed the frequency of all ICDs in a population of nicotine-dependent women compared to non-smoking women. We also checked criteria of two other impulsive behaviours, compulsive buying and bulimia. Methods. Five hundred consecutive patients were assessed by a general practitioner in Paris (France). One hundred and twenty-seven women presenting the DSM-IV-R criteria for nicotine dependence were included. They were compared to 127 women consulting the same practitioner but who did not smoke. Diagnosis of ICD (pyromania, kleptomania, trichotillomania, intermittent explosive disorder, pathological gambling) and of bulimia was based on DSM-IV criteria and a modified version of the Minnesota Impulsive Disorders Interview (MIDI). Diagnosis of compulsive buying was made with the McElroy et al. criteria and a specific questionnaire. Cigarette smoking was studied using the Fagerstrm questionnaire and the DSM-IV-R criteria for nicotine dependence. Alcohol use disorders were assessed with the DSM-IV-R criteria for dependence and the CAGE and the MAST questionnaires. Results. Thirteen patients presented trichotillomania, 22 explosive intermittent disorder and 12 pathological gambling. All these diagnoses were equally frequent in the nicotine-positive and nicotine-negative groups. We found no case of pyromania. Compulsive buying was the most frequent impulse control disorder. It was significantly more frequent in the nicotine-positive group than in the nicotine-negative group (58 vs. 39 cases, P=0.01). Scores of the compulsive buying scale were higher in the nicotine-positive group (4.07 vs. 2.9, P=0.01). None of the patients presented an association of two or more ICDs. Patients from the nicotine-positive group drunk higher quantities of alcohol each day, consumed alcohol more frequently each week and were more often intoxicated each week with alcohol. Their mean MAST scores of alcohol abuse disorders were higher. Conclusion. A total of 45.6% of the nicotine-dependent women presented compulsive buying and 23.6% bulimia. Compulsive buying was significantly more frequent among nicotine-dependent subjects than controls. Other impulse control disorders were as frequent among nicotine-dependent women as in controls. A total of 8.6% presented explosive intermittent disorder, 4.7% pathological gambling and 5% trichotillomania. Nicotine dependence in women was also associated with a higher level of alcohol consumption. These results indicate the possible need to systematically screen nicotine-dependent women, regardless of their motivation for consultation, for alcohol dependence, bulimia and compulsive buying. PMID:24941141

  16. Stability Analysis and Design of Impulsive Control Lorenz Systems Family

    International Nuclear Information System (INIS)

    Lorenz systems family unifying Lorenz system, Chen system and Lue system is a typical chaotic family. In this paper, we consider impulsive control Lorenz chaotic systems family with time-varying impulse intervals. By establishing an effective tool of a set of inequalities, we analyze the asymptotic stability of impulsive control Lorenz systems family and obtain some new less conservative conditions. Based on the stability analysis, we design a novel impulsive controller with time-varying impulse intervals. Illustrative examples are provided to show the feasibility and effectiveness of our method. The obtained results not only can be used to design impulsive control for Lorenz systems family, but also can be extended to other chaotic systems. (general)

  17. State-dependent impulses boundary value problems on compact interval

    CERN Document Server

    Rachůnková, Irena

    2015-01-01

    This book offers the reader a new approach to the solvability of boundary value problems with state-dependent impulses and provides recently obtained existence results for state dependent impulsive problems with general linear boundary conditions. It covers fixed-time impulsive boundary value problems both regular and singular and deals with higher order differential equations or with systems that are subject to general linear boundary conditions. We treat state-dependent impulsive boundary value problems, including a new approach giving effective conditions for the solvability of the Dirichlet problem with one state-dependent impulse condition and we show that the depicted approach can be extended to problems with a finite number of state-dependent impulses. We investigate the Sturm–Liouville boundary value problem for a more general right-hand side of a differential equation. Finally, we offer generalizations to higher order differential equations or differential systems subject to general linear boundary...

  18. Multidimensional Examination of Impulsivity in Relation to Disordered Gambling

    OpenAIRE

    MacKillop, James; Miller, Joshua D; Fortune, Erica; Maples, Jessica; Lance, Charles E.; Campbell, W. Keith; Adam S. Goodie

    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...

  19. Impulsive generalized function synchronization of complex dynamical networks

    International Nuclear Information System (INIS)

    This Letter investigates generalized function synchronization of continuous and discrete complex networks by impulsive control. By constructing the reasonable corresponding impulsively controlled response networks, some criteria and corollaries are derived for the generalized function synchronization between the impulsively controlled complex networks, continuous and discrete networks are both included. Furthermore, the generalized linear synchronization and nonlinear synchronization are respectively illustrated by several examples. All the numerical simulations demonstrate the correctness of the theoretical results

  20. Boundary conditions of the exact impulse wave function

    International Nuclear Information System (INIS)

    The behavior of the exact impulse wave function is investigated at intermediate and high impact energies. Numerical details of the wave function and its perturbative potential are reported. We conclude that the impulse wave function does not tend to the proper Coulomb asymptotic limit. For electron capture, however, it is shown that the impulse wave function produces reliable probabilities even for intermediate velocities and symmetric collision systems. copyright 1997 The American Physical Society

  1. Prediction of BMI by impulsivity, eating behavior and activity level

    OpenAIRE

    Jiang Xiaxia; Hong Yanping

    2016-01-01

    Objective: Discuss the relationship between the impulsivity, eating behavior and activity level and the body mass index (BMI). Method: Test 147 female college students with the impulsivity questionnaire (BIS-11 and BIS/BAS), Dutch Eating Behavior Questionnaire (DBEQ), Sitting Time Scale (STS) and Exercising Time Scale (ETS). Results: (1) The correlation analysis indicates that BMI and impulsivity (r = 0.43 and 0.52) have a significant positive correlation with the sitting time (r = 0.61) and ...

  2. SIMULATION OF IMPULSE VOLTAGE TESTING OF POWER TRANSFORMERS USING PSPICE

    OpenAIRE

    Lavkesh Patidar *; Hemant Sawarkar

    2015-01-01

    Impulse generator is an indispensible high voltage set. It simulates the voltage due to lightning and switching surges and used for testing of insulation of various electrical equipments like transformer, insulators etc. The standard impulse waveform could be used to test the strength of electrical equipments against the lightning. Lightning characteristics and standard impulse wave form are related to each other. But the lack of realization about relation between them would make ...

  3. Eyes Wide Shopped: Shopping Situations Trigger Arousal in Impulsive Buyers

    OpenAIRE

    Serfas, Benjamin G.; Büttner, Oliver B.; Florack, Arnd

    2014-01-01

    The present study proposes arousal as an important mechanism driving buying impulsiveness. We examined the effect of buying impulsiveness on arousal in non-shopping and shopping contexts. In an eye-tracking experiment, we measured pupil dilation while participants viewed and rated pictures of shopping scenes and non-shopping scenes. The results demonstrated that buying impulsiveness is closely associated with arousal as response to viewing pictures of shopping scenes. This pertained for hedon...

  4. Does mass media fuel, and easy credit facilitate, impulse buys?

    OpenAIRE

    Huovinen, Pasi; Rouvinen, Petri

    2008-01-01

    This paper studies whether exposure to mass media and liking advertising are associated with an increased impulse buy tendency, and whether the availability of a credit card acts as a facilitating stimulus. It is found that impulse buys are positively associated with exposure to commercial television, but not to other forms of mass media. For females, liking advertising in general is positively associated with impulse buying; for males, having a preference for informative advertising is negat...

  5. DTI and impulsivity in schizophrenia: a first voxelwise correlational analysis

    OpenAIRE

    Hoptman, Matthew J.; Ardekani, Babak A.; Butler, Pamela D.; Nierenberg, Jay; Javitt, Daniel C.; Lim, Kelvin O.

    2004-01-01

    Compromised white matter (WM) integrity in inferior frontal WM has been related to impulsivity in men with schizophrenia. However, these relationships may be more widespread. Fractional anisotropy (FA) derived from diffusion tensor imaging of 25 men with schizophrenia was transformed into Talairach space. Correlations between FA and impulsiveness were examined on a voxelwise basis. We found negative correlations between FA and impulsivity in inferior frontal WM, anterior cingulate, caudate, i...

  6. Stability of impulsive neural networks with time delays

    International Nuclear Information System (INIS)

    Since Hopfield neural networks have a wide application in our life, it is important to study it. In this Letter, we consider the stability of the equilibrium point of the impulsive Hopfield-type neural networks systems with time delays. By using Lyapunov functions and analysis technique, we get a result for the uniform stability of the equilibrium point of the impulsive Hopfield-type neural networks systems with time delays. We can see that impulses do contribute to system's stability behavior

  7. Effects of Strategies Marketing of Collective Buying about Impulsive Behavior

    OpenAIRE

    Suzi Elen Ferreira Dias; Rosilene Maria dos Santos; Vinicius Martins; Giuliana Isabella

    2014-01-01

    Brazil has the second largest e-commerce market in the world. One model used in this sector is "collective buying", a feature of which is impulse sales. Consumer behavior can be influenced by several factors, two of which are addressed in this article: the individual impulsivity of consumers and strategies of mix marketing. Impulsive buying is characterized by an unplanned purchase, i.e. the need to acquire the product arises just before the purchase. Consumers respond differently to mixed st...

  8. Effect of checkout stands' assortment heterogeneity on impulsive purchases

    OpenAIRE

    Canelas, Susana Isabel Monginho

    2014-01-01

    In-store consumer behavior has been comprehensively studied throughout the last decades. It is a fact that consumers are from day to day increasing their in-store decision making levels, whether through unplanned or impulsive purchases. However, it is believed that impulsive buying behavior through point-of-purchase marketing activities increases the profits of retailers on the long-run (Baumeister, 2002). It is also considered that impulsive purchases occur more frequently and are more signi...

  9. Virtual Shopping and Impulse Purchasing Strengths and Weaknesses in Pakistan

    OpenAIRE

    Muhammad Ali Hussain; Muhammad Zeeshan Anwar; Humna Mehboob; Ayesha Majeed; Tanzila Samin

    2011-01-01

    This research analyzed the perceptive of consumers doing online shopping and impulse purchasing. This study examined the behavior of thirty consumers who were asked to fill the questionnaire based on some close ended questions. The focus of this investigation was to discuss the strengths and Weaknesses of online shopping and impulse purchasing in developing country like Pakistan. Today consumers choose and buy things while sitting at home through internet and buy things impulsively. Do consum...

  10. Numerical Analysis of Impulse Turbine for Isolated Pilot OWC System

    OpenAIRE

    Zhen Liu(Pittsburgh Particle physics, Astrophysics, and Cosmology Center, Department of Physics and Astronomy, University of Pittsburgh, 3941 OHara St., Pittsburgh, PA 15260, U.S.A.); Jiyuan Jin; Ying Cui; Haiwen Fan

    2013-01-01

    Oscillating water column (OWC) is the most widely used wave energy converting technology in the world. The impulse turbine is recently been employed as the radial turbine in OWC facilities to convert bidirectional mechanical air power into electricity power. 3D numerical model for the impulse turbine is established in this paper to investigate its operating performance of the designed impulse turbine for the pilot OWC system which is under the construction on Jeju Island, Republic of Korea. T...

  11. Application of E^p-Stability to Impulsive Financial Model

    OpenAIRE

    Sam Olatunji Ale; Benjamin Oyediran Oyelami

    2013-01-01

    In this paper, we consider an impulsive stochastic model for an investment with production and saving profiles. The conditions for financial growth for the investment are investigated under impulsive action and results are obtained using the quantitative and Ep stability methods. The impulsive stochastic differential equation considered is assumed to be driven by a process with jump and non-linear gestation properties. One of the results established shows that, in the long run, it is impossib...

  12. Impulsivity in Animal Models for Drug Abuse Disorders

    OpenAIRE

    Jentsch, J. David

    2008-01-01

    Different conceptual frameworks have been generated to explain substance abuse; of relevance to this article, dysfunction of impulse control systems that are required for avoiding or stopping drug-seeking and –taking may play a key role in addiction. This review summarizes work in animal models that explains the pervasive association between impulse control and substance abuse. It further underscores the concept that impulse control may be a critical target for pharmacological intervention in...

  13. The genetic correlation between procrastination and impulsivity.

    Science.gov (United States)

    Loehlin, John C; Martin, Nicholas G

    2014-12-01

    The reported genetic correlation of 1.0 between the traits of procrastination and impulsivity (Gustavson, D. E., Miyake, A., Hewitt, J. K., & Friedman, N. P. (2014). Psychological Science), which was held to support an evolutionary origin of the relationship between the two traits, was tested in data from two large samples of twins from Australia. A genetic correlation of 0.299 was obtained. It was concluded that, although the presence of a genetic correlation between the two traits was supported, the modest magnitude of the correlation was such as to be consistent with many possible hypotheses, evolutionary and otherwise, about causal relationships between the traits in question. PMID:25431285

  14. High power impulse magnetron sputtering discharge

    OpenAIRE

    Gudmundsson, J. T.; Brenning, N; Lundin, Daniel; Helmersson, Ulf

    2012-01-01

    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...

  15. Impulse absorption by horizontal magnetic granular chain

    Directory of Open Access Journals (Sweden)

    Dingxin Leng

    2016-02-01

    Full Text Available The granular medium is known as a protecting material for shock mitigation. We study the impulse absorption of an alignment of magnetic spheres placed horizontally under a non-uniform magnetic field. The phenomenon of the wave dispersion is presented. This system can absorb 85% ∼ 95% (88% ∼ 98% of the incident peak force (energy under the applied magnetic field strength in 0.1 T ∼ 1.0 T. The shock attenuation capacities are enhanced by the increment of field strength. With an intelligent control system, it is conceivable that the magnetic granular chain may offer possibilities in developing adaptive shock protectors.

  16. Whistler observations during a magnetospheric sudden impulse

    International Nuclear Information System (INIS)

    Whistlers recorded at Siple, Antarctica (76degreeS, 84degreeW), show sudden changes in nose frequency (f/subn/) in response to a magnetospheric sudden impulse (si) on June 9, 1973. These changes are partly due to changes in local magnetic field strength and partly due to the motion of the duct under the influence of induced electric field. This example is used to illustrate how ground-based VLF radio techniques can be used to monitor the dynamic response of the magnetosphere to shocks and discontinuities in the solar wind

  17. Dynamical mechanical systems under random impulses

    CERN Document Server

    Iwankiewicz, R

    1995-01-01

    The book presents the methods of analysis of dynamical mechanical systems subjected to stochastic excitations in form of random trains of impulses. This particular class of excitations is adequately characterized by stochastic point processes and behaviour of dynamical systems is governed by stochastic differential equations driven by point processes. Based on the methods of point processes the analytical techniques are devised to characterize the response of linear and nonlinear mechanical systems as the solutions of underlying stochastic differential equations. A number of example problems o

  18. Transient Impulsive Giant Electronic Raman Redistribution

    CERN Document Server

    Miyabe, S

    2014-01-01

    Resonant Raman excitation by ultrafast vacuum ultraviolet laser pulses is a powerful means to study electron dynamics in molecules, but experiments must contend with linear background ionization: frequencies high enough to reach resonant core-valence transitions will usually ionize all occupied orbitals as well, and the ionization cross sections are usually dominant. Here we show that attosecond pulses can induce a new process, transient impulsive stimulated Raman scattering, which can overwhelm valence ionization. Calculations are performed for atomic sodium, but the principal is valid for many molecular systems. This approach opens the path for high fidelity multidimensional spectroscopy with attosecond pulses.

  19. Prueba de impulso cefálico Head impulse test

    Directory of Open Access Journals (Sweden)

    Hayo A Breinbauer K

    2011-08-01

    Full Text Available Introducción: Dentro del estudio de la función del equilibrio, la prueba de impulso cefálico representa una herramienta rápida, sencilla y de fácil interpretación, que explora la indemnidad del reflejo óculo-vestibular. Este examen ha cobrado relevancia reciente como complemento a la prueba calórica en diversos contextos y no ha sido explorado en nuestro país. Objetivo: Explorar sensibilidad y especificidad de esta prueba en nuestro contexto local, junto con contribuir a la difusión de una herramienta de creciente relevancia en otoneurología. Material y método: Estudio prospectivo, ciego, de evaluación de test diagnóstico. En una muestra de pacientes consultando por vértigo agudo se realizó prueba de impulso cefálico al momento de la consulta inicial, y al momento de realizar prueba funcional de VIII par. Resultados: Se evaluaron 52 pacientes, 44% de ellos con disfunción vestibular según prueba calórica clásica como patrón de oro. La sensibilidad de la prueba de impulso cefálico fue de 47,6% y su especificidad de 83,9%, con un valor predictivo positivo y negativo de 66,7% y 70,3%. El acuerdo del examen entre dos evaluadores independientes fue alto (Kappa = 0,84. Discusiones: A pesar de una baja sensibilidad por sí sola, la prueba de impulso cuenta con una alta especificidad y un valor predictivo positivo razonable. Es además altamente reproducible, realizable en menos de un minuto y no genera náuseas u otros síntomas en el paciente. Consideramos este examen como un complemento al estudio de la función vestibular, con implicaciones prácticas en el inicio precoz de terapia y con importantes potencialidades en diversos ámbitos de la otoneurología.Introduction: In balance function evaluation, head impulse test is a fast, simple and easy to interpret test, which explores the vestibulo-ocular reflex. Having gained in the last decade growing importance as a complement to traditional caloric test, this test hasn't been explored in our context yet. Aim: To assess sensitivity and specificity of this test in our context, along with contributing to the spread of an increasingly important tool in otoneurology Material and method: A prospective, blinded, diagnostic test assessment. In a sample of patients consulting for acute vertigo, head impulse test was performed at the time of initial consultation, and at the time of VIII nerve functional testing. Results: We evaluated 52 patients, 44% with vestibular dysfunction as shown in caloric test results as gold standard. Sensitivity of the head impulse test was 47.6%, its specificity 83.9%, with positive and negative predictive value of 66.7% and 70.3% respectively. Agreement between two independent examiners was high (Kappa = 0.84. Discussion: Despite its low sensitivity, impulse test showed a high specificity and a reasonable positive predictive value. It was also highly reproductible, and generates no nausea or other symptoms in the patient. We consider this test as a complement to vestibular function evaluation, with clinical applicationssupportingearly onset of therapy. We believe this test to withhold significant potential in various otoneurological developing applications.

  20. CHECK AND CONTROL ELECTRONIC SYSTEM IN MAGNETIC-IMPULSE SETUP WITH MULTIPLE REPEATING OF DISCHARGE IMPULSES

    Directory of Open Access Journals (Sweden)

    G.Kaljanov

    2009-01-01

    Full Text Available The modern microprocessor system controling the complex of electromagnetic flattening of vehicles is created in this work. Microprocessor system for control and check of magnetic-impulse setup meets the formulated conditions for the conversion on the other level of modern electro technical devices.

  1. Modified impulsive synchronization of fractional order hyperchaotic systems

    International Nuclear Information System (INIS)

    In this paper, a modified impulsive control scheme is proposed to realize the complete synchronization of fractional order hyperchaotic systems. By constructing a suitable response system, an integral order synchronization error system is obtained. Based on the theory of Lyapunov stability and the impulsive differential equations, some effective sufficient conditions are derived to guarantee the asymptotical stability of the synchronization error system. In particular, some simpler and more convenient conditions are derived by taking the fixed impulsive distances and control gains. Compared with the existing results, the main results in this paper are practical and rigorous. Simulation results show the effectiveness and the feasibility of the proposed impulsive control method. (general)

  2. Dissecting impulsivity and its relationships to drug addictions.

    Science.gov (United States)

    Jentsch, J David; Ashenhurst, James R; Cervantes, M Catalina; Groman, Stephanie M; James, Alexander S; Pennington, Zachary T

    2014-10-01

    Addictions are often characterized as forms of impulsive behavior. That said, it is often noted that impulsivity is a multidimensional construct, spanning several psychological domains. This review describes the relationship between varieties of impulsivity and addiction-related behaviors, the nature of the causal relationship between the two, and the underlying neurobiological mechanisms that promote impulsive behaviors. We conclude that the available data strongly support the notion that impulsivity is both a risk factor for, and a consequence of, drug and alcohol consumption. While the evidence indicating that subtypes of impulsive behavior are uniquely informative--either biologically or with respect to their relationships to addictions--is convincing, multiple lines of study link distinct subtypes of impulsivity to low dopamine D2 receptor function and perturbed serotonergic transmission, revealing shared mechanisms between the subtypes. Therefore, a common biological framework involving monoaminergic transmitters in key frontostriatal circuits may link multiple forms of impulsivity to drug self-administration and addiction-related behaviors. Further dissection of these relationships is needed before the next phase of genetic and genomic discovery will be able to reveal the biological sources of the vulnerability for addiction indexed by impulsivity. PMID:24654857

  3. Diagnostics and Impulse Performance of Laser-Ablative Propulsion

    Science.gov (United States)

    Sasoh, Akihiro; Mori, Koichi; Anju, Kohei; Suzuki, Koji; Shimono, Masaya; Sawada, Keisuke

    2008-04-01

    Pressure time variations and associated flows induced by pulsed laser ablation were experimentally studied using the Velocity Interferometer System for Any Reflector (VISAR) and framing Schlieren visualization. The combination of either aluminum or polyacetal target and TEA CO2 laser pulse were examined. The VISAR measurement resolved that the pressure modulated from the laser power variation in the impulse generation processes. Integrated impulse induced by repetative CO2 laser pulses was measured using a torsion-type impulse balance. The effect of the ambient pressure was significant. The measured impulse characteristics were closely associated with target surface morphology and fluid dynamics.

  4. Diagnostics and Impulse Performance of Laser-Ablative Propulsion

    International Nuclear Information System (INIS)

    Pressure time variations and associated flows induced by pulsed laser ablation were experimentally studied using the Velocity Interferometer System for Any Reflector (VISAR) and framing Schlieren visualization. The combination of either aluminum or polyacetal target and TEA CO2 laser pulse were examined. The VISAR measurement resolved that the pressure modulated from the laser power variation in the impulse generation processes. Integrated impulse induced by repetative CO2 laser pulses was measured using a torsion-type impulse balance. The effect of the ambient pressure was significant. The measured impulse characteristics were closely associated with target surface morphology and fluid dynamics

  5. Sleep and Impulsivity in Parkinson’s Disease

    Science.gov (United States)

    Scullin, Michael K.; Sollinger, Ann B.; Land, Julia; Wood-Siverio, Cathy; Zanders, Lavezza; Lee, Raven; Freeman, Alan; Goldstein, Felicia C.; Bliwise, Donald L.; Factor, Stewart A.

    2013-01-01

    Background Impulsive behavior and poor sleep are important non-motor features of Parkinson’s disease (PD) that negatively impact the quality of life of patients and their families. Previous research suggests a higher level of sleep complaints in PD patients who demonstrate impulsive behaviors, but the nature of the sleep disturbances has yet to be comprehensively tested. Methods Consecutive idiopathic PD patients (N=143) completed the Minnesota Impulse Disorder Interview and a sleep questionnaire that assessed sleep efficiency, excessive daytime sleepiness, restless legs symptoms, snoring, dreams/nightmares, and nocturia. Patients were also given a Unified Parkinson’s Disease Rating Scale motor examination and they completed cognitive testing. Results Impulsive PD patients endorsed more sleep complaints than non-impulsive PD patients. The group difference was primarily attributable to poor sleep efficiency (e.g., greater nocturnal awakenings), p < .01, and greater daytime sleepiness, p < .01, in the impulsive PD patients. Interestingly, restless legs symptoms were also greater in the impulsive PD patients, p < .05. The results could not be explained by medications or disease severity. Conclusions Poor sleep efficiency, restless legs symptoms, and increased daytime sleepiness are associated with impulsivity in PD. Longitudinal studies are needed to determine whether sleep disturbances precede impulsivity in PD. PMID:23880026

  6. Impulsive and reflective processes related to alcohol use in young adolescents

    Directory of Open Access Journals (Sweden)

    SaraPieters

    2014-05-01

    Full Text Available Background: Dual process models suggest that the development of addictive behaviors is the result of interplay between impulsive and reflective processes, modulated by boundary conditions such as individual or situational factors. Empirical support for this model has been repeatedly demonstrated in adult samples (for a meta-analysis see Rooke, Hine, & Thorsteinsson, 2008. The purpose of this study was to test these processes as they relate to emerging alcohol use in adolescents. Specifically, the interactive effects of several measures of impulsive and reflective processes and working memory capacity are examined as predictors of changes in alcohol use among adolescents. It was expected that measures of reflective processes would better predict changes in alcohol use than measures of impulsive processes. Moreover, it was anticipated that working memory capacity would moderate the relation between alcohol-specific impulsive and reflective processes and changes in adolescent alcohol use. Methods: The sample consisted of 427 adolescents (47.7% male between 12 and 16 years of age (M = 13.96, SD = .78 who reported drinking alcohol at least once. Four measures of impulsive processes were included. Attentional bias for alcohol was assessed with a Visual Probe Test; approach bias toward alcohol was assessed with a Stimulus Response Compatibility Test (SRC; and memory associations with alcohol were assessed with an Implicit Association Test (IAT and a Word Association Test (WAT. Two measures of reflective measures were included: positive and negative expectancies. Working memory capacity was measured using a Self-Ordered Pointing Task (SOPT. Results: Results showed that positive expectancies predicted changes in alcohol use, but this effect was qualified by an interaction with IAT scores. Moreover, SRC scores predicted changes in alcohol use only when negative expectancies were low. Attentional bias and word association scores did not predict changes in alcohol us

  7. Effects of multiple scatter on the propagation and absorption of electromagnetic waves in a field-aligned-striated cold magneto-plasma: implications for ionospheric modification experiments

    Science.gov (United States)

    Robinson, T. R.

    2002-01-01

    A new theory of the propagation of low power electromagnetic test waves through the upper-hybrid resonance layer in the presence of magnetic field-aligned plasma density striations, which includes the effects of multiple scatter, is presented. The case of sinusoidal striations in a cold magnetoplasma is treated rigorously and then extended, in an approximate manner, to the broad-band striation spectrum and warm plasma cases. In contrast to previous, single scatter theories, it is found that the interaction layer is much broader than the wavelength of the test wave. This is due to the combined electric fields of the scattered waves becoming localised on the contour of a fixed plasma density, which corresponds to a constant value for the local upper-hybrid resonance frequency over the whole interaction region. The results are applied to the calculation of the refractive index of an ordinary mode test wave during modification experiments in the ionospheric F-region. Although strong anomalous absorption arises, no new cutoffs occur at the upper-hybrid resonance, so that in contrast to the predictions of previous single scatter theories, no additional reflections occur there. These results are consistent with observations made during ionospheric modification experiments at Tromsø, Norway.

  8. Effects of multiple scatter on the propagation and absorption of electromagnetic waves in a field-aligned-striated cold magneto-plasma: implications for ionospheric modification experiments

    Directory of Open Access Journals (Sweden)

    T. R. Robinson

    Full Text Available A new theory of the propagation of low power electromagnetic test waves through the upper-hybrid resonance layer in the presence of magnetic field-aligned plasma density striations, which includes the effects of multiple scatter, is presented. The case of sinusoidal striations in a cold magnetoplasma is treated rigorously and then extended, in an approximate manner, to the broad-band striation spectrum and warm plasma cases. In contrast to previous, single scatter theories, it is found that the interaction layer is much broader than the wavelength of the test wave. This is due to the combined electric fields of the scattered waves becoming localised on the contour of a fixed plasma density, which corresponds to a constant value for the local upper-hybrid resonance frequency over the whole interaction region. The results are applied to the calculation of the refractive index of an ordinary mode test wave during modification experiments in the ionospheric F-region. Although strong anomalous absorption arises, no new cutoffs occur at the upper-hybrid resonance, so that in contrast to the predictions of previous single scatter theories, no additional reflections occur there. These results are consistent with observations made during ionospheric modification experiments at Tromsø, Norway.

    Key words. Ionosphere (active experiments; ionospheric irregularities Radio science (ionospheric propagation

  9. Correlations between the disintegration of melt and the measured impulses in steam explosions

    Energy Technology Data Exchange (ETDEWEB)

    Froehlich, G.; Linca, A.; Schindler, M. [Univ. of Stuttgart (Germany)

    1995-09-01

    To find our correlations in steam explosions (melt water interactions) between the measured impulses and the disintegration of the melt, experiments were performed in three configurations i.e. stratified, entrapment and jet experiments. Linear correlations were detected between the impulse and the total surface of the fragments. Theoretical considerations point out that a linear correlation assumes superheating of a water layer around the fragments of a constant thickness during the fragmentation process to a constant temperature (here the homogeneous nucleation temperature of water was assumed) and a constant expansion velocity of the steam in the main expansion time. The correlation constant does not depend on melt temperature and trigger pressure, but it depends on the configuration of the experiment or of a scenario of an accident. Further research is required concerning the correlation constant. For analysing steam explosion accidents the explosivity is introduced. The explosivity is a mass specific impulse. The explosivity is linear correlated with the degree of fragmentation. Knowing the degree of fragmentation with proper correlation constant the explosivity can be calculated and from the explosivity combined with the total mass of fragments the impulse is obtained which can be used to an estimation of the maximum force.

  10. Correlations between the disintegration of melt and the measured impulses in steam explosions

    International Nuclear Information System (INIS)

    To find our correlations in steam explosions (melt water interactions) between the measured impulses and the disintegration of the melt, experiments were performed in three configurations i.e. stratified, entrapment and jet experiments. Linear correlations were detected between the impulse and the total surface of the fragments. Theoretical considerations point out that a linear correlation assumes superheating of a water layer around the fragments of a constant thickness during the fragmentation process to a constant temperature (here the homogeneous nucleation temperature of water was assumed) and a constant expansion velocity of the steam in the main expansion time. The correlation constant does not depend on melt temperature and trigger pressure, but it depends on the configuration of the experiment or of a scenario of an accident. Further research is required concerning the correlation constant. For analysing steam explosion accidents the explosivity is introduced. The explosivity is a mass specific impulse. The explosivity is linear correlated with the degree of fragmentation. Knowing the degree of fragmentation with proper correlation constant the explosivity can be calculated and from the explosivity combined with the total mass of fragments the impulse is obtained which can be used to an estimation of the maximum force

  11. Insulation Characteristics of CO2 Gas for Non-standard Lightning Impulse Oscillations

    Science.gov (United States)

    Yokoi, Tetsuhiko; Kaneko, Shuhei; Okabe, Shigemitsu

    To improve GIS insulation specifications, it is important to recognize the insulation characteristics under oscillatory overvoltage waveforms occurring in the field. The actual lightning surge waveform (called non-standard lightning impulse waveform) in actual substations is different from the standard lightning impulse waveform (1.2/50μs). The actual lightning surge waveform generally rises steeply, however, the decay of the overvoltage is large, and the insulation requirements are not as severe as those of the standard lightning impulse waveform. Since SF6 gas was identified as a greenhouse gas at COP3 in 1997, alternative insulation gases to SF6 have been investigated. The CO2 gas insulation is one of the candidates, which is a natural gas and has lower global warming potential (GWP). V-t characteristics with CO2 showed a steep decline than SF6 and the effects of oscillation on the insulation characteristics with CO2 are not definite under the condition of frequency up to 4.0MHz. This paper describes the insulation characteristics of CO2 gas for single-frequency oscillatory waveforms with various frequencies from 5.3 to 20.0MHz and damping ratios. From experimental investigation, similarly to SF6, it might be possible to reduce the test voltage of CO2 gas insulation system by evaluating actual lightning surge waveform in terms of the equivalent standard lightning impulse waveform.

  12. Design and construction of an impulse turbine

    International Nuclear Information System (INIS)

    Impulse turbine has been constructed to be used in the program of Hydraulic Machines, Faculty of Mechanical Engineering at the Universidad Pontificia Bolivariana, sede Bucaramanga. For construction of the impulse turbine (Pelton) detailed plans were drawn up taking into account the design and implementation of the fundamental equations of hydraulic turbomachinery. From the experimental data found maximum mechanical efficiency of 0.6 ± 0.03 for a water flow of 2.1 l/s. The maximum overall efficiency was 0.23 ± 0.02 for a water flow of 0.83 l/s. The design parameter used was a power of 1 kW, as flow regulator built a needle type regulator, which performed well, the model of the bucket or vane is built on a machine type CNC (Computer Numerical Control). For the construction of the impeller and blades was used aluminium because of chemical and physical characteristics and the casing was manufactured in acrylic

  13. Force-Time Entropy of Isometric Impulse.

    Science.gov (United States)

    Hsieh, Tsung-Yu; Newell, Karl M

    2016-01-01

    The relation between force and temporal variability in discrete impulse production has been viewed as independent (R. A. Schmidt, H. Zelaznik, B. Hawkins, J. S. Frank, & J. T. Quinn, 1979 ) or dependent on the rate of force (L. G. Carlton & K. M. Newell, 1993 ). Two experiments in an isometric single finger force task investigated the joint force-time entropy with (a) fixed time to peak force and different percentages of force level and (b) fixed percentage of force level and different times to peak force. The results showed that the peak force variability increased either with the increment of force level or through a shorter time to peak force that also reduced timing error variability. The peak force entropy and entropy of time to peak force increased on the respective dimension as the parameter conditions approached either maximum force or a minimum rate of force production. The findings show that force error and timing error are dependent but complementary when considered in the same framework with the joint force-time entropy at a minimum in the middle parameter range of discrete impulse. PMID:26375900

  14. Low cost impulse compatible wideband antenna

    Science.gov (United States)

    Rosenbury, Erwin T. (Livermore, CA); Burke, Gerald J. (Livermore, CA); Nelson, Scott D. (Tracy, CA); Stever, Robert D. (Lathrop, CA); Governo, George K. (Livermore, CA); Mullenhoff, Donald J. (Livermore, CA)

    2002-01-01

    An antenna apparatus and method for building the antenna is disclosed. Impulse signals travel through a feed point of the antenna with respect to a ground plane. A geometric fin structure is connected to the feed point, and through a termination resistance to the ground plane. A geometric ridge structure connected to the ground is positioned with respect to the fin in order to receive and radiate electromagnetic energy from the impulse signal at a predetermined impedance and over a predetermined set of frequencies. The fin and ridge can be either a wire or a planar surface. The fin and ridge may be disposed within a radiation cavity such as a horn. The radiation cavity is constructed of stamped and etched metal sheets bent and then soldered together. The fin and ridge are also formed from metal sheets or wires. The fin is attached to the feed point and then to the cavity through a termination resistance. The ridge is attached to the cavity and disposed with respect to the fin in order to achieve a particular set of antenna characteristics.

  15. Design and construction of an impulse turbine

    Science.gov (United States)

    Hernández, E.

    2013-11-01

    Impulse turbine has been constructed to be used in the program of Hydraulic Machines, Faculty of Mechanical Engineering at the Universidad Pontificia Bolivariana, sede Bucaramanga. For construction of the impulse turbine (Pelton) detailed plans were drawn up taking into account the design and implementation of the fundamental equations of hydraulic turbomachinery. From the experimental data found maximum mechanical efficiency of 0.6 ± 0.03 for a water flow of 2.1 l/s. The maximum overall efficiency was 0.23 ± 0.02 for a water flow of 0.83 l/s. The design parameter used was a power of 1 kW, as flow regulator built a needle type regulator, which performed well, the model of the bucket or vane is built on a machine type CNC (Computer Numerical Control). For the construction of the impeller and blades was used aluminium because of chemical and physical characteristics and the casing was manufactured in acrylic.

  16. Concrete structures under impact and impulsive loading

    International Nuclear Information System (INIS)

    This book contains papers contributed to the RILEM/CEB/IABSE/IASS-Interassociation Symposium on 'Concrete Structures under Impact and Impulsive Loading'. The essential aim of this symposium is to provide an international forum for the exchange of information on existing and current research relating to impact problems as well as to identify areas to which further research activities should be directed. The subject of the symposium is far ranging. Fifty five papers were proposed and arranged in six technical sessions, a task which sometimes posed difficulties for the Organization Committee and the Advisory Group, because some of the papers touched several topics and were difficult to integrate. However, we are confident that these minor difficulties were solved to the satisfaction of everyone involved. Each session of the symposium is devoted to a major subject area and introduced by a distinguished Introductory Reporter. The large international attendance, some 21 countries are represented, and the large number of excellent papers will certainly produce a lively discussion after each session and thus help to further close the gaps in our knowledge about the behaviour of structures and materials under impact and impulsive loading. (orig./RW)

  17. Electrode Erosion of a High Energy Impulse Spark Gap Switch

    International Nuclear Information System (INIS)

    Based on the principle of thermal conduction, three metal alloys (stainless steel, copper-tungsten and graphite) were chosen as the material of the high impulse current discharging switch. Experimental results indicate that the mass loss and surface erosion morphology of the electrode are related with the electrode material (conductivity σ, melting point Tm, density ρ and thermal capacity c) and the impulse transferred charge (or energy) per impulse for the same total impulse transferred charge. The experimental results indicate that the mass loss of stainless steel, copper-tungsten and graphite are 380.10 μg/C, 118.10 μg/C and 81.90 μg/C respectively under the condition of a total impulse transferred charge of 525 C and a transferred charge per impulse of 10.5 C. Under the same impulse transferred charge, the mass loss of copper-tungsten (118.10 μg/C) with the transferred charge per impulse at 10.5 C is far larger than the mass loss (38.61 μg/C) at a 1.48 C transferred charge per impulse. The electrode erosion mechanism under high energy impulse arcs is analyzed briefly and it is suggested that by selecting high conductive metal or metal alloy as the electrode material of a high energy impulse spark gap switch and setting high erosion resistance material at the top of the electrode, the mass loss of the electrode can be reduced and the life of the switch prolonged

  18. College drinking behaviors: mediational links between parenting styles, impulse control, and alcohol-related outcomes.

    Science.gov (United States)

    Patock-Peckham, Julie A; Morgan-Lopez, Antonio A

    2006-06-01

    Mediational links between parenting styles (authoritative, authoritarian, permissive), impulsiveness (general control), drinking control (specific control), and alcohol use and abuse were tested. A pattern-mixture approach (for modeling non-ignorable missing data) with multiple-group structural equation models with 421 (206 female, 215 male) college students was used. Gender was examined as a potential moderator of parenting styles on control processes related to drinking. Specifically, the parent-child gender match was found to have implications for increased levels of impulsiveness (a significant mediator of parenting effects on drinking control). These findings suggest that a parent with a permissive parenting style who is the same gender as the respondent can directly influence control processes and indirectly influence alcohol use and abuse. PMID:16784353

  19. Epidemiologic and clinical updates on impulse control disorders: a critical review.

    Science.gov (United States)

    Dell'Osso, Bernardo; Altamura, A Carlo; Allen, Andrea; Marazziti, Donatella; Hollander, Eric

    2006-12-01

    The article reviews the current knowledge about the impulse control disorders (ICDs) with specific emphasis on epidemiological and pharmacological advances. In addition to the traditional ICDs present in the DSM-IV-pathological gambling, trichotillomania, kleptomania, pyromania and intermittent explosive disorder-a brief description of the new proposed ICDs-compulsive-impulsive (C-I) Internet usage disorder, C-I sexual behaviors, C-I skin picking and C-I shopping-is provided. Specifically, the article summarizes the phenomenology, epidemiology and comorbidity of the ICDs. Particular attention is paid to the relationship between ICDs and obsessive-compulsive disorder (OCD). Finally, current pharmacological options for treating ICDs are presented and discussed. PMID:16960655

  20. Impulsive integral equations in Banach spaces and applications

    Directory of Open Access Journals (Sweden)

    Dajun Guo

    1992-01-01

    Full Text Available In this paper, we first use the fixed point theory to prove two existence theorems of positive solutions for the impulsive Fredholm integral Equations in Banach spaces. And then, we offer some applications to the two-point boundary value problems for the second order impulsive differential equations in Banach spaces.

  1. Existence of periodic solutions of impulsive differential systems

    Directory of Open Access Journals (Sweden)

    L. H. Erbe

    1991-01-01

    Full Text Available In this paper, the existence of periodic solutions of impulsive differential systems is considered. Since the solutions of such a system are peicewise continuous, it is necessary to introduce piecewise continuous Lyapunov functions. By means of such functions, together with the comparison principle, some sufficient conditions for the existence of periodic solutions of impulsive differential systems are established.

  2. Impulsive Control for Fractional-Order Chaotic Systems

    International Nuclear Information System (INIS)

    We propose an impulsive control scheme for fractional-order chaotic systems. Based on the TakagiSugeno (T-S) fuzzy model and linear matrix inequalities (LMIs), some sufficient conditions are given to stabilize the fractional-order chaotic system via impulsive control. Numerical simulation shows the effectiveness of this approach. (general)

  3. Geodesics in spacetimes with expanding impulsive gravitational waves

    International Nuclear Information System (INIS)

    We study geodesic motion in expanding spherical impulsive gravitational waves propagating in a Minkowski background. Employing the continuous form of the metric we find and examine a large family of geometrically preferred geodesics. For the special class of axially symmetric spacetimes with the spherical impulse generated by a snapping cosmic string we give a detailed physical interpretation of the motion of test particles

  4. A Measure of Impulsiveness and its Relations to Extraversion.

    Science.gov (United States)

    Lorr, Maurice; Wunderlich, Richard A.

    1985-01-01

    The construct validity of the Impulsive scale of the Interpersonal Style Inventory (ISI), and its relation to Eysenck's extraversion were investigated. High school males completed self report personality measures. They were rated by counselors on an impulsive scale. Counselor ratings correlated at a significant level with self-report scores.…

  5. Sex Differences in Impulsivity: A Meta-Analysis

    Science.gov (United States)

    Cross, Catharine P.; Copping, Lee T.; Campbell, Anne

    2011-01-01

    Men are overrepresented in socially problematic behaviors, such as aggression and criminal behavior, which have been linked to impulsivity. Our review of impulsivity is organized around the tripartite theoretical distinction between reward hypersensitivity, punishment hyposensitivity, and inadequate effortful control. Drawing on evolutionary,

  6. Effects of Strategies Marketing of Collective Buying about Impulsive Behavior

    Directory of Open Access Journals (Sweden)

    Suzi Elen Ferreira Dias

    2014-08-01

    Full Text Available Brazil has the second largest e-commerce market in the world. One model used in this sector is "collective buying", a feature of which is impulse sales. Consumer behavior can be influenced by several factors, two of which are addressed in this article: the individual impulsivity of consumers and strategies of mix marketing. Impulsive buying is characterized by an unplanned purchase, i.e. the need to acquire the product arises just before the purchase. Consumers respond differently to mixed strategies depending on their degree of impulsivity. Thus, this article aims to analyze the efficacy of different marketing mix strategies for impulsive and non-impulsive consumer purchasing behavior. 137 participants were given a questionnaire containing the Buying Impulsiveness scale from Rook and Fisher (1995, and statements about the marketing strategies used by collective buying sites. Through a regression analysis, three strategies were found to relate more to impulsivity: search for products from well-known brands, search for deals with big discounts and confidence in receiving the product. For e-commerce and researchers, this study elucidates which strategies, from the consumer's perspective, effectively persuade purchasing behavior.

  7. Maximum Atmospheric Entry Angle for Specified Retrofire Impulse

    Directory of Open Access Journals (Sweden)

    T. N. Srivastava

    1969-07-01

    Full Text Available Maximum atmospheric entry angles for vehicles initially moving in elliptic orbits are investigated and it is shown that tangential retrofire impulse at the apogee results in the maximum entry angle. Equivalence of maximizing the entry angle and minimizing the retrofire impulse is also established.

  8. Individual Differences in Impulsive Choice and Timing in Rats

    Science.gov (United States)

    Galtress, Tiffany; Garcia, Ana; Kirkpatrick, Kimberly

    2012-01-01

    Individual differences in impulsive choice behavior have been linked to a variety of behavioral problems including substance abuse, smoking, gambling, and poor financial decision-making. Given the potential importance of individual differences in impulsive choice as a predictor of behavioral problems, the present study sought to measure the extent…

  9. Asymptotic behavior of second-order impulsive differential equations

    Directory of Open Access Journals (Sweden)

    Haifeng Liu

    2011-02-01

    Full Text Available In this article, we study the asymptotic behavior of all solutions of 2-th order nonlinear delay differential equation with impulses. Our main tools are impulsive differential inequalities and the Riccati transformation. We illustrate the results by an example.

  10. Playmancer project: a serious videogame as additional therapy tool for eating and impulse control disorders

    OpenAIRE

    Dimitri Konstantas; Todor Ganchev; Tony Lam; Santamaría, Juan J.; Christian Breiteneder; Costas Davarakis

    2009-01-01

    Reviews and few non-controlled studies showed the effectiveness of several specific designed computer video-games as additional form of treatment in several areas. However, there is a lack in the literature of specially designed serious-games for treating mental disorders. Playmancer (ICT European initiative) aims to develop and assess a serious videogame that may help to treat underlying processes (e.g. lack of self-control strategies) in Eating and Impulse control disorders. Preliminary dat...

  11. Evaluation of behavioral impulsivity and aggression tasks as endophenotypes for borderline personality disorder

    OpenAIRE

    McCloskey, Michael S.; Antonia S. New; Larry J Siever; Goodman, Marianne; Koenigsberg, Harold W; Flory, Janine D.; Coccaro, Emil F.

    2009-01-01

    Borderline personality disorder (BPD) is marked by aggression and impulsive, often self-destructive behavior. Despite the severe risks associated with BPD, relatively little is known about the disorder’s etiology. Identification of genetic correlates (endophenotypes) of BPD would improve the prospects of targeted interventions for more homogeneous subsets of borderline patients characterized by specific genetic vulnerabilities. The current study evaluated behavioral measures of aggression and...

  12. Shoppers' motivations at the airport; The impact of impulse buying tendency and time-pressure

    OpenAIRE

    Sepp, Katri

    2014-01-01

    OBJECTIVES: The purpose of this study is to expand the understanding of the factors influencing customer behavior in airport retailing environment. More specifically, the focus is on Asian customers visiting the Finnair Tax-Free Shop at Helsinki Airport. The aim of the study is to find out how shopping motivations are affected by time pressure and impulse buying tendency, as both are factors related strongly to the shopping in the airport environment. METHODS: The study draws on ...

  13. Same-sex attraction in homophobic men: The role of impulsive processes

    OpenAIRE

    Guerra Meneses, Adrianne

    2015-01-01

    While the underlying causes of homophobia are not fully understood, one theory claims it stems from an unconscious or denied attraction to the same-sex. A study by Adams, Wright, and Lohr (1996) found evidence of this same-sex attraction in homophobic men, but other studies have shown mixed results. Drawing on dual-process models, this study tested the assumption that in homophobic men, sexual interest in homosexual stimuli depends on their specific impulses towards these stimuli. Thirty-eigh...

  14. Neutronics analysis of an open-cycle high-impulse gas core reactor concept

    Science.gov (United States)

    Whitmarsh, C. L., Jr.

    1972-01-01

    A procedure was developed to calculate the critical fuel mass, including the effects of propellant pressure, for coaxial-flow gas-core reactors operating at 196,600 newtons thrust and 4400 seconds specific impulse. Data were generated for a range of cavity diameter, reflector-moderator thickness, and quantity of structural material. Also presented are such core characteristics as upper limits on cavity pressure, spectral hardening in very-high-temperature hydrogen, and reactivity coefficients.

  15. Permanence of a General Periodic Single-Species System with Periodic Impulsive Perturbations

    OpenAIRE

    Liu, Xianning; TAKEUCHI, Yasuhiro

    2007-01-01

    Sufficient conditions for permanence of a general periodic single-species system with periodic impulsive perturbations are obtained via comparison theory of impulsive differential equations. An application is given to the periodic impulsive logistic system.

  16. Virtual Shopping and Impulse Purchasing Strengths and Weaknesses in Pakistan

    Directory of Open Access Journals (Sweden)

    Muhammad Ali Hussain

    2011-11-01

    Full Text Available This research analyzed the perceptive of consumers doing online shopping and impulse purchasing. This study examined the behavior of thirty consumers who were asked to fill the questionnaire based on some close ended questions. The focus of this investigation was to discuss the strengths and Weaknesses of online shopping and impulse purchasing in developing country like Pakistan. Today consumers choose and buy things while sitting at home through internet and buy things impulsively. Do consumer in Pakistan are using Internet for shopping online? Do they make more impulse purchase on the Internet? Does online shopping save time? Do online shopping is more attractive or consumer feels lack of trust? Impacts of advertising are also discussed. We covered the virtual shopping weakness and strengths in our VSIPSWP (Virtual Shopping and Impulse Purchasing Strengths and Weaknesses in Pakistan Models.

  17. Impulse Testing of Corporate-Fed Patch Array Antennas

    Science.gov (United States)

    Chamberlain, Neil F.

    2011-01-01

    This paper discusses a novel method for detecting faults in antenna arrays. The method, termed Impulse Testing, was developed for corporate-fed patch arrays where the element is fed by a probe and is shorted at its center. Impulse Testing was devised to supplement conventional microwave measurements in order to quickly verify antenna integrity. The technique relies on exciting each antenna element in turn with a fast pulse (or impulse) that propagates through the feed network to the output port of the antenna. The resulting impulse response is characteristic of the path through the feed network. Using an oscilloscope, a simple amplitude measurement can be made to detect faults. A circuit model of the antenna elements and feed network was constructed to assess various fault scenarios and determine fault-detection thresholds. The experimental setup and impulse measurements for two patch array antennas are presented. Advantages and limitations of the technique are discussed along with applications to other antenna array topologies

  18. Chaotic attitude control of satellite using impulsive control

    International Nuclear Information System (INIS)

    Nowadays, attitude control systems of satellites demand better performance, resulting in the application of new advanced nonlinear control theory. In this paper, impulsive control is applied to a six-dimensional system which describes the attitude dynamics of a satellite subjected to deterministic external perturbations which induce chaotic motion when no control is affected. Several theorems on the stability of impulsive control systems are presented. These theorems are then used to find the conditions under which the chaotic systems can be asymptotically controlled to the origin by using impulsive control. Given the parameters of the chaotic system and the impulsive control law, an estimation of the upper bound of the impulse interval is given. Finally, we give some simulations results to visualize the effectiveness and feasibility of the proposed method.

  19. Chaotic attitude control of satellite using impulsive control

    Energy Technology Data Exchange (ETDEWEB)

    Kemih, Karim [LAMEL Laboratory, Electrical Department, Jijel University, BP 98, 18000 Jijel (Algeria)], E-mail: K_kemih@yahoo.fr; Kemiha, Adel [Electronics Department, Jijel University, BP 98, 18000 Jijel (Algeria); Ghanes, Malek [ENSEA 06 Avenue du Ponceau, 95014 Cergy-pontoise Cedex (France)

    2009-10-30

    Nowadays, attitude control systems of satellites demand better performance, resulting in the application of new advanced nonlinear control theory. In this paper, impulsive control is applied to a six-dimensional system which describes the attitude dynamics of a satellite subjected to deterministic external perturbations which induce chaotic motion when no control is affected. Several theorems on the stability of impulsive control systems are presented. These theorems are then used to find the conditions under which the chaotic systems can be asymptotically controlled to the origin by using impulsive control. Given the parameters of the chaotic system and the impulsive control law, an estimation of the upper bound of the impulse interval is given. Finally, we give some simulations results to visualize the effectiveness and feasibility of the proposed method.

  20. Atmospheric Disturbances and Radiation Impulses Caused by Large-Meteoroid Impacts on the Surface of Mars. II. Radiation Impulse Characteristics and Parameters of the Warm Layer

    Science.gov (United States)

    Kosarev, I. B.; Loseva, T. V.; Nemtchinov, I. V.; Shuvalov, V. V.; Greely, R.

    2002-07-01

    This paper presents the results of the calculation of spectral and angular characteristics of radiation emitted by the disturbed region after the vertical impacts on the Martian surface of stony meteoroids with radii R0 from 1 to 100 m at speeds of 11-20 km/s. The time dependences are given for the density of the radiation flux incident on horizontal surface areas located at different distances from the impact point. For small impactors (R0 = 1 m), the heating of the surface and surrounding gas by the radiation impulse from the hot region formed after the impact is insignificant even at the crater edge. However, the radiation impulse that heats up the surface is also emitted during the meteoroid flight through the atmosphere. Although this heating is insufficient to initiate evaporation, heat transfer by turbulent diffusion leads to the formation of a layer with temperatures that substantially exceed the initial temperature of the atmosphere. For large impactors (R0 = 100 m), the total specific impulse of the plume radiation gives rise to the emergence of the heated layer with a thickness on the order of several meters within several kilometers of the impact point. The formation of this ``warm'' layer may lead to the formation of a high-speed jet moving along the Martian surface as well as eddies at the front of the precursor with a subsequent intense rise of dust.

  1. Bright 30 THz Impulsive Solar Bursts

    CERN Document Server

    Kaufmann, P; Marcon, R; Kudaka, A S; Cabezas, D P; Cassiano, M M; Francile, C; Fernandes, L O T; Ramirez, R F Hidalgo; Luoni, M; Marun, A; Pereyra, P; de Souza, R V

    2015-01-01

    Impulsive 30 THz continuum bursts have been recently observed in solar flares, utilizing small telescopes with a unique and relatively simple optical setup concept. The most intense burst was observed together with a GOES X2 class event on October 27, 2014, also detected at two sub-THz frequencies, RHESSI X-rays and SDO/HMI and EUV. It exhibits strikingly good correlation in time and in space with white light flare emission. It is likely that this association may prove to be very common. All three 30 THz events recently observed exhibited intense fluxes in the range of 104 solar flux units, considerably larger than those measured for the same events at microwave and sub-mm wavelengths. The 30 THz burst emission might be part of the same spectral burst component found at sub-THz frequencies. The 30 THz solar bursts open a promising new window for the study of flares at their origin

  2. Magnetospheric plasma drift during a sudden impulse

    International Nuclear Information System (INIS)

    An interplanetary shock front (monitored by the ISEE 1/2 satellite pair)= hit the earth's magnetosphere on October 17, 1978, around 0430 UT. The changes in magnetospheric plasma drift and magnetic field associated with this sudden impulse (SI) were measured by GEOS 2 in the equatorial plane near the dawn meridian. After the SI the plasma drift first increased (in an inward direction), followed by an exponential decay. The magnetic field changes were purely compressional with an amplitude increase which also exponentially decayed. These features can be explained by adiabatic (quasi-static) compression of the magnetopause due to the increased solar wind pressure behind the shock front. In addition, both data sets exhibit also the excitation of a highly damped compressional hydromagnetic oscillation by the SI, thus hinting of a second, wavelike component in the compression of the magnetosphere

  3. Investigation of gas discharge impulse image intensifiers

    CERN Document Server

    Gushchin, E M; Timofeev, M K

    1999-01-01

    The gas discharge impulse image intensifiers (GDIII) operated in the streamer mode are studied in this work. The GDIII has a resolution of 5-15 lines/cm and light amplification up to approx 10 sup 1 sup 0. The possibility to design a single-electron GDIII for RICH-detectors is considered. For this purpose the emission of photoelectrons in He, Ne, Ar, Xe, CO sub 2 , iC sub 4 H sub 1 sub 0 and their mixtures in the 50-760 Torr pressure range have been investigated. The best working gas for the GDIII is Ne+(approx 0.1%)iC sub 4 H sub 1 sub 0 mixture having an electron output factor up to 0.45.

  4. Abulia and impulsiveness revisited: a conceptual history.

    Science.gov (United States)

    Berrios, G E; Gili, M

    1995-09-01

    Historical analysis suggests that the decline and fall of the will was due not to any major piece of empirical work demonstrating that the concept was unsound but to general changes in philosophical fashion, and to the temporary influence of the anti-mentalistic tenets of behaviorism and the anti-volitional assumptions of psychoanalysis. Clinical disorders like abulia and impulsiveness share conceptual features that 19th-century alienists captured well in their clinical category of disorder of the will. Current accounts, which include semi-explanatory concepts such as "drive", "motivation" or frontal lobe "executive" are not conceptually better than the old notion of will nor are they superior as correlational variables for neurobiological studies. It is suggested that the will, updated according to modern work in the philosophy of action, be re-adopted as a research category in current psychiatry. PMID:7484191

  5. Impulsivity components measured by the Brazilian version of the Barratt Impulsiveness Scale (BIS-11

    Directory of Open Access Journals (Sweden)

    Alina Gomide Vasconcelos

    2015-03-01

    Full Text Available The main purpose of this study was to investigate the psychometric properties of the Barratt Impulsiveness Scale (BIS-11. Content item analysis was conducted by seven doctoral students. A convenience sample of 897 students was submitted to BIS-11 and they also filled self-reports about Minor Mental Disorder and ADHD symptoms, alcohol use and cigarette smoking. Mean age was 27.32 (SD=8.69 years, 56% were female and 52% had incomplete college degree. Content and factorial analyses revealed that impulsivity was best represented by two latent factors labeled non-planning and inhibition behaviors. Test retest agreement tended to produce similar score patterns seven months after the first evaluation. Additionally, BIS-11 scores discriminated subjects in terms of cigarette smoking and psychopathological symptoms, which indicated evidences regarding criterion-related validity. The theoretical discussion was present based on the neuropsychological model of hot and cool aspects of executive function.

  6. Ionospheric current contribution to the main impulse of a negative sudden impulse

    Science.gov (United States)

    Vichare, Geeta; Rawat, Rahul; Bhaskar, Ankush; Pathan, Bashir M.

    2014-12-01

    The geomagnetic field response to a moderate-amplitude negative sudden impulse (SI-) that occurred on 14 May 2009 at 10:30 UT was examined at 97 geomagnetic observatories situated all over the globe. The response signature contains a contribution from magnetospheric as well as ionospheric currents. The main impulse (MI) is defined as the maximum depression in the observed geomagnetic field. It is observed that for low-to-high latitudes, the amplitude of the MI is larger in the afternoon to post-dusk sector than in the dawn-noon sector, indicating asymmetry in the MI amplitude. We estimated the contribution at various observatories due to the Chapman-Ferraro magnetopause currents using the Tsyganenko model (T01) and subtracted this from the observed MI amplitude to obtain the contribution due to ionospheric currents. It is found that the ionospheric currents contribute significantly to the MI amplitude of moderate SI- even at low-to-mid latitudes and that the contribution is in the same direction as that from the magnetopause currents near dusk and in the opposite direction near dawn. The equivalent current vectors reveal a clockwise (anticlockwise) ionospheric current loop in the afternoon (morning) sector during the MI of the negative pressure impulse. This evidences an ionospheric twin-cell-vortex current system (DP2) due to field-aligned currents (FACs) associated with the dusk-to-dawn convection electric field during the MI of an SI-. We also estimated the magnetic field variation due to prompt penetration electric fields, which is found to be very small at low latitudes in the present case. The studied SI- is not associated with shock, and hence no preliminary reverse impulse was evident. In addition, the summer hemisphere reveals larger MI amplitudes than the winter hemisphere, indicating once again the role of ionospheric currents.

  7. Breakdown Characteristics of Gas Insulated Switchgears for Non-standard Lightning Impulse Waveforms under Non-uniform Electric Field

    Science.gov (United States)

    Ueta, Genyo; Kaneko, Shuhei; Okabe, Shigemitsu

    To improve insulation specification of a gas insulated switchgear (GIS), it is necessary to recognize the insulation characteristics of SF6 gas under actual surge (called non-standard lightning impulse waveform) occurring in the field substation. The authors had observed the insulation characteristics of SF6 gas gap under various types of non-standard lightning impulse waveforms and compared them with under standard lightning impulse waveform quantitatively. From the investigation of the experimental results, the evaluation method for real surges is shown and the method is applied to typical surges for various UHV and 500kV systems. In the proceeding study, therefore, only for the quasi-uniform electric field (with a typical range of the field utilization factors in the bus of a GIS) was investigated. In this paper, the insulation characteristics of SF6 gas gap for non-uniform electric field were observed experimentally and investigated about the evaluation method of converting non-standard lightning impulse waveforms equivalently to the standard lightning impulse waveform.

  8. Stability of Impulsive Differential Equation with any Time Delay

    Directory of Open Access Journals (Sweden)

    Sanjay K. Srivastava

    2013-03-01

    Full Text Available In this paper, the stability of general impulsive retarded functional differential equations with any time delay has been considered. Many evolution processes are characterized by the fact that at certain moments of time they experience a change of state abruptly. Consequently, it is natural to assume that these perturbations act instantaneously, that is, in the form of impulses. Impulsive differential equations, that is, differential equations involving impulse effects, are a natural description of observed evolution phenomena of several real world problems. Impulsive control which based on impulsive differential equations has attracted the interest of many researchers recently. The method of Lyapunov functions and Razumikhin technique have been widely applied to stability analysis of various delay differential equation. When Lyapunov functions are used, it becomes necessary to choose an appropriate minimal class of functionals relative to which the derivative of the Lyapunov function is estimated. This approach is known as the Lyapunov–Razumikhin technique. When Lyapunov functionals are used the corresponding derivative can be estimated without demanding minimal classes of functional. By using Lyapunov functions and analysis technique along with Razumikhin technique, some results for the uniform stability of such impulsive differential equations have been derived. The obtained results extend and generalize some results existing in the literature.

  9. Impulse control disorders in non-treatment seeking hair pullers.

    Science.gov (United States)

    Schreiber, Liana R N; Lust, Katherine; Odlaug, Brian; Derbyshire, Katherine L; Grant, Jon

    2013-06-01

    Background and aims Hair pulling is a common body focused repetitive behavior. The purpose of this paper is to examine the prevalence of impulse control disorders (as defined in DSM-IV-TR) in a non-treatment seeking sample of hair pullers. Methods 1,717 college students with (n = 44) and without (n = 1673) hair pulling completed a mental health survey. The college students were sent an online survey assessing hair pulling behavior and other impulse control disorders using the Minnesota Impulsive Disorders Interview. Results Students with hair pulling were significantly more likely to have a co-occurring impulse control disorder (20.5% vs. 8.9%, p = 0.009, OR = 2.71, CI = 1.28-5.75) and were significantly more likely to meet criteria for compulsive buying, compulsive sexual behavior and intermittent explosive disorder than students without hair pulling. Differences seemed to be moderated by the male gender among students with hair pulling. Discussion and conclusions Hair pulling is often comorbid with another impulse control disorder, which suggests that elements of impulsivity may be important in our understanding of hair pulling. Furthermore, gender may moderate impulse control comorbidity in hair pulling disorder. PMID:26165931

  10. Negative emotion-driven impulsivity predicts substance dependence problems.

    Science.gov (United States)

    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. PMID:17629632

  11. Tomographic reconstruction of indoor spatial temperature distributions using room impulse responses

    Science.gov (United States)

    Bleisteiner, M.; Barth, M.; Raabe, A.

    2016-03-01

    Temperature can be estimated by acoustic travel time measurements along known sound paths. By using a multitude of known sound paths in combination with a tomographic reconstruction technique a spatial and temporal resolution of the temperature field can be achieved. Based on it, this article focuses on an experimental method in order to determine the spatially differentiated development of room temperature with only one loudspeaker and one microphone. The theory of geometrical room acoustics is being used to identify sound paths under consideration of reflections. The travel time along a specific sound path is derived from the room impulse response. Temporal variances in room impulse response can be attributed primarily to a change in air temperature and airflow. It is shown that in the absence of airflow a 3D acoustic monitoring of the room temperature can be realized with a fairly limited use of hardware.

  12. Correlation Between Steady State and Impulse Earth Resistance Values

    Directory of Open Access Journals (Sweden)

    N. M. Nor

    2009-01-01

    Full Text Available This study presented experimental results of earthing systems under low-magnitude currents and under high impulse currents. The details of the measuring circuit involved for both types of testing were described. Three field sites were selected. At each site, three earth electrodes configurations were used. This makes up to nine earthing systems. From both low magnitude and impulse tests, the correlation between the steady state earth resistance value and the earth resistance under fast impulse currents can be observed. The relation between the calculated and measured steady state earth resistance is also shown in this study.

  13. CO2 laser with long impulsions of high energy

    International Nuclear Information System (INIS)

    Though they are similar in principle as the short impulsion laser, the CO2 long pulsation are less sophisticated and expensive. So they can be used by middle class laboratories where the matter-laser interaction is studied. The obtain long impulsions, it is necessary to limit the value of the current density in the electron gun which is realized in locating a grid connected to the ground by an ohmic resistance between the cathode and the anode of this gun. The two long impulsion lasers (6 and 10 ?s) of the Institut of Mecanique des Fluides, Universite d'Aix-Marseille I are described and the characteristics of their working are presented

  14. The definition of electro impulses used in weed control

    Directory of Open Access Journals (Sweden)

    Judaev I.V.

    2008-01-01

    Full Text Available In modern agriculture the use of chemicals and machines in weed control is not environmental and soil friendly. The use of electro impulses is offered to traditional ways of weed control. The researches done on technical characteristics of such operation and influence of these results on ecology gave picture that the use of electro impulses in weed control is harmless for environment and that is very effective. The basis for the technical project at designing of the electro impulse installation used with standard wheel tractor obtained data about values of electric energy doses that can make damage in various kinds of weeds.

  15. Impulse control in Kalman-like filtering problems

    Directory of Open Access Journals (Sweden)

    Michael V. Basin

    1998-01-01

    Full Text Available This paper develops the impulse control approach to the observation process in Kalman-like filtering problems, which is based on impulsive modeling of the transition matrix in an observation equation. The impulse control generates the jumps of the estimate variance from its current position down to zero and, as a result, enables us to obtain the filtering equations for the Kalman estimate with zero variance for all post-jump time moments. The filtering equations for the estimates with zero variances are obtained in the conventional linear filtering problem and in the case of scalar nonlinear state and nonlinear observation equations.

  16. Assortment of optimal conditions for running the impulse diode thermometer

    Science.gov (United States)

    Iskrenovic, P. S.; Mitic, D. B.

    1994-02-01

    In the algorithm for iterative evaluation of temperature measured by the p-n junction in the impulse regime two voltages appear as parameters. Their values are limited only by the operating characteristics of the impulse diode thermometer, i.e., both values must fall within the interval determined by the hardware normal operating conditions. The choice of these values within the allowed interval seems to be arbitrary; however, analysis of the expression for relative measurement errors leads to the criterion for the optimal choice of these parameters that allow the impulse diode thermometer to operate with the maximal resolution and minimal error.

  17. Towards Ultrahigh Speed Impulse Radio THz Wireless Communications

    DEFF Research Database (Denmark)

    Yu, Xianbin; Galili, Michael; Morioka, Toshio; Jepsen, Peter Uhd; Oxenløwe, Leif Katsuo

    2015-01-01

    evaluate the realistic throughput and accessible wireless range of a THz impulse radio communication link based on a uni-travelling photodiode (UTC-PD) as THz emitter and a photoconductive antenna (PCA) as THz receiver. The impact of highly frequency-selective THz channel and the noise in the system are......THz impulse radio technologies promise a new paradigm of fast wireless access with simplified wireless reception. However, huge loss of propagating broad bandwidth THz impulse radio signals limits THz wireless transmission distance and reduces the achievable link data rates. In this paper, we...

  18. Transient Positive Horizontal Head Impulse Test in Pregabalin Intoxication.

    Science.gov (United States)

    Jeong, Seong-Hae; Kim, Yong Soo; Lee, Ju-Hoen; Jo, Hyunjin; Lee, Ae Young; Kim, Jae-Moon

    2015-12-01

    Head impulse test (HIT) is helpful to understanding high-frequency vestibulo-ocular reflex in patients with dizziness and imbalance. There are some reports on abnormal HITs in cerebellar disorder. To our knowledge, there was no report of transient bilateral positive head impulse related to antiepileptic drugs. A 65-year-old woman developed dizziness and imbalance after treatment with pregabalin for pain control of radiation cystitis. Neurological examination exhibited positive bilateral HIT results, in addition to ataxia and gaze-evoked rebound nystagmus. Pregabalin intoxication can evoke transient positive horizontal head impulse test as another indicator of cerebellar dysfunction. PMID:26819943

  19. A Serious Videogame as an Additional Therapy Tool for Training Emotional Regulation and Impulsivity Control in Severe Gambling Disorder

    Science.gov (United States)

    Tárrega, Salomé; Castro-Carreras, Laia; Fernández-Aranda, Fernando; Granero, Roser; Giner-Bartolomé, Cristina; Aymamí, Neus; Gómez-Peña, Mónica; Santamaría, Juan J.; Forcano, Laura; Steward, Trevor; Menchón, José M.; Jiménez-Murcia, Susana

    2015-01-01

    Background: Gambling disorder (GD) is characterized by a significant lack of self-control and is associated with impulsivity-related personality traits. It is also linked to deficits in emotional regulation and frequently co-occurs with anxiety and depression symptoms. There is also evidence that emotional dysregulation may play a mediatory role between GD and psychopathological symptomatology. Few studies have reported the outcomes of psychological interventions that specifically address these underlying processes. Objectives: To assess the utility of the Playmancer platform, a serious video game, as an additional therapy tool in a CBT intervention for GD, and to estimate pre-post changes in measures of impulsivity, anger expression and psychopathological symptomatology. Method: The sample comprised a single group of 16 male treatment-seeking individuals with severe GD diagnosis. Therapy intervention consisted of 16 group weekly CBT sessions and, concurrently, 10 additional weekly sessions of a serious video game. Pre-post treatment scores on South Oaks Gambling Screen (SOGS), Barratt Impulsiveness Scale (BIS-11), I7 Impulsiveness Questionnaire (I7), State-Trait Anger Expression Inventory 2 (STAXI-2), Symptom Checklist-Revised (SCL-90-R), State-Trait Anxiety Inventory (STAI-S-T), and Novelty Seeking from the Temperament and Character Inventory-Revised (TCI-R) were compared. Results: After the intervention, significant changes were observed in several measures of impulsivity, anger expression and other psychopathological symptoms. Dropout and relapse rates during treatment were similar to those described in the literature for CBT. Conclusion: Complementing CBT interventions for GD with a specific therapy approach like a serious video game might be helpful in addressing certain underlying factors which are usually difficult to change, including impulsivity and anger expression. PMID:26617550

  20. High power impulse magnetron sputtering discharge

    Energy Technology Data Exchange (ETDEWEB)

    Gudmundsson, J. T.; Brenning, N.; Lundin, D.; Helmersson, U. [University of Michigan--Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240 (China) and Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Division of Space and Plasma Physics, School of Electrical Engineering, Royal Institute of Technology, SE-100 44, Stockholm (Sweden); Plasma and Coatings Division, IFM-Materials Physics, Linkoeping University, SE-581 83, Linkoeping (Sweden)

    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.

  1. On reactive high power impulse magnetron sputtering

    Science.gov (United States)

    Gudmundsson, J. T.

    2016-01-01

    High power impulse magnetron sputtering (HiPIMS) is an ionized physical vapor deposition (IPVD) technique that is particularly promising for reactive sputtering applications. However, there are few issues that have to be resolved before the full potential of this technique can be realized. Here we give an overview of the key experimental findings for the reactive HiPIMS discharge. An increase in the discharge current is commonly observed with increased partial pressure of the reactive gas or decreased repetition pulse frequency. There are somewhat conflicting claims regarding the hysteresis effect in the reactive HiPIMS discharge as some report reduction or elimination of the hysteresis effect while others claim a feedback control is essential. The ion energy distribution of the metal ion and the atomic ion of the reactive gas are similar and extend to very high energies while the ion energy distribution of the working gas and the molecular ion of the reactive gas are similar and are much less energetic.

  2. Minimum Impulse Thruster Valve Design and Development

    Science.gov (United States)

    Huftalen, R.; Parker, J. P.; Platt, A.; Yankura, G.

    2004-10-01

    The design and development of a minimum impulse thruster valve was conducted, by Moog, under contract by NASA's Jet Propulsion Laboratory, California Institute of Technology, for deep space propulsion systems. The effort was focused on applying known solenoid design techniques scaled to provide a 1-millisecond response capability for monopropellant, hydrazine ACS thruster applications. The valve has an extended operating temperature range of 20o F to +350o F with a total mass of less than 25 grams and nominal power draw of 7 watts. The design solution resulted in providing a solenoid valve that is one-tenth the scale of the standard product line. The valve has the capability of providing a mass flow rate of 0.0009 pounds per second hydrazine. The design life of 1,000,000 cycles was demonstrated both dry and wet. Not all design factors scaled as expected and proved to be the focus of the final development effort. These included the surface interactions, hydrodynamics and driver electronics. The resulting solution applied matured design approaches to minimize the program risk with innovative methods to address the impacts of scale.

  3. Bright 30 THz impulsive solar bursts

    Science.gov (United States)

    Kaufmann, P.; White, S. M.; Marcon, R.; Kudaka, A. S.; Cabezas, D. P.; Cassiano, M. M.; Francile, C.; Fernandes, L. O. T.; Hidalgo Ramirez, R. F.; Luoni, M.; Marun, A.; Pereyra, P.; Souza, R. V.

    2015-06-01

    Impulsive 30 THz continuum bursts have been recently observed in solar flares, utilizing small telescopes with a unique and relatively simple optical setup concept. The most intense burst was observed together with a GOES X2 class event on 27 October 2014, also detected at two subterahertz (sub-THz) frequencies, Reuven Ramaty High Energy Solar Spectroscopic Imager X-rays and Solar Dynamics Observatory/Helioseismic and Magnetic Imager and EUV. It exhibits strikingly good correlation in time and in space with white-light flare emission. It is likely that this association may prove to be very common. All three 30 THz events recently observed exhibited intense fluxes in the range of 104 solar flux units, considerably larger than those measured for the same events at microwave and submillimeter wavelengths. The 30 THz burst emission might be part of the same spectral burst component found at sub-THz frequencies. The 30 THz solar bursts open a promising new window for the study of flares at their origin.

  4. Reactive high power impulse magnetron sputtering

    Science.gov (United States)

    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

  5. High power impulse magnetron sputtering discharge

    International Nuclear Information System (INIS)

    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.

  6. Impulse formalism for atom-diatom collisions

    International Nuclear Information System (INIS)

    An exact formulation of the impulse approach (IA), or quantum-mechanical spectator model, is applied to atom-diatom collisions. Results are compared with previous work on the IA, which has always involved the peaking approximation (PA). The PA is seen to overestimate (underestimate) differential cross sections for processes involving projectile atom energy loss (gain). The internal consistency of the IA is explored by subjecting it to semidetailed balancing. For small scattering angles the IA is seen to be an inadequate theory, probably due to the neglect of double- and higher-collision terms in the multiple-collision expansion of the three-body T matrix. For large scattering angles, where the IA does appear to describe the scattering process accurately, the exact calculation is shown to give the same results as when only the energy-conserving on-the-energy-shell two-body processes are considered. An accurate approximation method is also developed for rapid computation of inelastic differential cross sections. Finally, the calculated results are compared with the experimental measurements, and the need to explore two-body potentials more complicated than the hard-core potential is pointed out

  7. Impulse control disorders in psychiatric inpatients.

    Science.gov (United States)

    Mller, Astrid; Rein, Katharina; Kollei, Ines; Jacobi, Andrea; Rotter, Andrea; Schtz, Patricia; Hillemacher, Thomas; de Zwaan, Martina

    2011-08-15

    The aim of this study was to examine the prevalence of impulse control disorders (ICDs) in a European psychiatric inpatient sample. Two hundred thirty four consecutive psychiatric inpatients (62% female) were examined using a module of the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders fourth edition (DSM-IV) that has been developed for ICDs (SCID-ICD). In addition to intermittent explosive disorder, pyromania, kleptomania, pathological gambling, and trichotillomania, the proposed ICDs not otherwise specified were assessed, including compulsive buying, nonparaphilic compulsive sexual behavior, pathological internet use, and pathological skin picking. Based on the SCID-ICD, a lifetime ICD rate of 23.5% and a current ICD rate of 18.8% were found. The most frequent ICDs were pathological skin picking (lifetime 7.3%, current 6.8%), compulsive buying (lifetime 6.8%, current 6.0%), and intermittent explosive disorder (lifetime 5.6%, current 3.4%). In contrast, referring to admission diagnoses taken from patients' charts only 3.8% of the inpatients were diagnosed with any current ICD. Individuals with comorbid ICD were significantly younger and had more admission diagnoses other than ICD. The results suggest high rates of ICDs among psychiatric inpatients that remain to be under-diagnosed in clinical routine. PMID:21546096

  8. Relationship between Impulsivity, Social Media Usage and Loneliness

    Directory of Open Access Journals (Sweden)

    Mustafa Savci

    2016-03-01

    Full Text Available The purpose of this study is to examine the relationships between impulsivity, social media usage, and loneliness and to test the structural hypothetical model developed based on the literature. The study was conducted on 307 (164 female, 143 male university students. Data collection instruments of the study were the Barratt Impulsivity Scale Short Form (BIS-11-SF, Social Media Usage Scale (SMUS, and UCLA Loneliness Scale Short Form (ULS-8. The measurement models of the latent variables were tested initially and it was observed that the scales of the latent variables were efficient enough to be included in the structural equation model. In addition, the suggested hypothetical model was tested. According to the analysis, it was observed that impulsivity directly, positively and significantly predicts social media usage, that social media usage directly, positively and significantly predicts loneliness, and that impulsivity indirectly, positively and significantly predicts loneliness.

  9. Channel Impulse Responses in Diffusive Molecular Communication with Spherical Transmitters

    CERN Document Server

    Noel, Adam; Hafid, Abdelhakim

    2016-01-01

    Molecular communication is an emerging paradigm for systems that rely on the release of molecules as information carriers. Communication via molecular diffusion is a popular strategy that is ubiquitous in nature and very fast over distances on the order of a micron or less. Existing closed-form analysis of the diffusion channel impulse response generally assumes that the transmitter is a point source. In this paper, channel impulse responses are derived for spherical transmitters with either a passive or absorbing receiver. The derived channel impulse responses are in closed-form for a one-dimensional environment and can be found via numerical integration for a three-dimensional environment. The point transmitter assumption (PTA) is formally defined so that its accuracy can be measured in comparison to the derived spherical transmitter impulse responses. The spherical transmitter model is much more accurate than the PTA when the distance between a transmitter and its receiver is small relative to the size of ...

  10. Self-Control and Impulsiveness Involving Aversive Events

    Science.gov (United States)

    Deluty, Marvin Z.

    1978-01-01

    A quantitative model is presented for understanding self-control and impulsiveness involving aversive events. Four experiments were conducted to test the model's adequacy in predicting how delay until punishment and duration of punishment affect choice. (Editor)

  11. The Relationship between Age and Impulsive Purchasing in Sri Lanka

    OpenAIRE

    Fernando, Charith Hubert

    2013-01-01

    The effect of age on impulsive buying has been extensively researched in the developed economies and to a limited extent in developing economies. However such research is not available for countries like Sri Lanka, which are experiencing a period of stability and economic growth following three decades of civil conflict that has had significant bearing on the population’s social behaviour. This research is an attempt to study the effect of age on factors that influence impulsive purchasing in...

  12. Geodesics in nonexpanding impulsive gravitational waves with $\\Lambda$

    CERN Document Server

    Sämann, Clemens; Lecke, Alexander; Podolský, Jiří

    2015-01-01

    We investigate the geodesics in the entire class of nonexpanding impulsive gravitational waves propagating in an (anti-)de Sitter universe using the distributional form of the metric. Employing a 5-dimensional embedding formalism and a general regularisation technique we prove existence and uniqueness of geodesics crossing the wave impulse leading to a completeness result. We also derive the explicit form of the geodesics thereby confirming previous results derived in a heuristic approach.

  13. Impulsive Choice Predicts Poor Working Memory in Male Rats

    OpenAIRE

    Renda, C. Renee; Stein, Jeffrey S.; Madden, Gregory J.

    2014-01-01

    A number of maladaptive behaviors and poor health outcomes (e.g., substance abuse, obesity) correlate with impulsive choice, which describes the tendency to prefer smaller, immediate rewards in lieu of larger, delayed rewards. Working memory deficits are often reported in those diagnosed with the same maladaptive behaviors. Human studies suggest that impulsive choice is associated with working memory ability but, to date, only one study has explored the association between working memory and ...

  14. Impulse Buying Behaviour of Young Males in an Airport Environment

    OpenAIRE

    Vänniä, Eeva

    2013-01-01

    The aim of this study is to conclude different areas and factors of impulse buying behaviours at the airport environment. The most important factors and research papers are researched on to find out how the topic has been regarded in the past. Impulse buying behaviour is a topic that has not been researched much on factors such as temporal factors and the effect of different environments. Air travelling is constantly increasing in popularity thus it was an interesting research topic for the a...

  15. Developmental role of acetylcholinesterase in impulse control in zebrafish

    OpenAIRE

    Parker, Matthew O.; Muy-Teck Teh; Fraser Combe

    2015-01-01

    Cellular and molecular processes that mediate individual variability in impulsivity, a key behavioural component of many neuropsychiatric disorders, are poorly understood. Zebrafish heterozygous for a nonsense mutation in Ache (achesb55/+) showed lower levels of impulsivity in a 5-choice serial reaction time task (5-CSRTT) than wild type and ache+/+. Assessment of expression of cholinergic (nAChR), serotonergic (5-HT) and dopamine (DR) receptor mRNA in both adult and larval (9dpf) achesb55/+ ...

  16. Developmental role of acetylcholinesterase in impulse control in zebrafish

    OpenAIRE

    Parker, Matthew O.; Brock, Alistair J.; Sudwarts, Ari; Teh, Muy-Teck; Combe, Fraser J.; Brennan, Caroline H.

    2015-01-01

    Cellular and molecular processes that mediate individual variability in impulsivity, a key behavioral component of many neuropsychiatric disorders, are poorly understood. Zebrafish heterozygous for a nonsense mutation in ache (ache sb55/+) showed lower levels of impulsivity in a 5-choice serial reaction time task (5-CSRTT) than wild type and ache+∕+. Assessment of expression of cholinergic (nAChR), serotonergic (5-HT), and dopamine (DR) receptor mRNA in both adult and larval (9 dpf) ache sb55...

  17. Switched impulsive control of the endocrine disruptor diethylstilbestrol singular model

    Science.gov (United States)

    Zamani, Iman; Shafiee, Masoud; Ibeas, Asier; de la Sen, M.

    2014-12-01

    In this work, a switched and impulsive controller is designed to control the Endocrine Disruptor Diethylstilbestrol mechanism which is usually modeled as a singular system. Then the exponential stabilization property of the proposed switched and impulsive singular model is discussed under matrix inequalities. A design algorithm is given and applied for the physiological process of endocrine disruptor diethylstilbestrol model to illustrate the effectiveness of the results.

  18. Impulsive and Compulsive Behaviors in Parkinsons Disease

    OpenAIRE

    Zhang, Guoxin; Zhang, Zhentao(School of Physics, Peking University, Beijing 100871, China); Liu, Ling; Yang, Jiaolong; Huang, Jinsha; Xiong, Nian; Wang, Tao

    2014-01-01

    Background: Impulsive and compulsive behaviors (ICBs) are a heterogeneous group of conditions that may be caused by long-term dopaminergic replacement therapy (DRT) of Parkinsons disease (PD). The spectrum of ICBs includes dopamine dysregulation syndrome (DDS), punding, and impulse control disorders (ICDs). Contents: We made a detailed review regarding the epidemiology, pathology, clinical characteristics, risk factors, diagnosis as well as treatment of ICBs. Results: The prevalence of...

  19. Impulsive and Compulsive Behaviors in Parkinsons Disease

    OpenAIRE

    Guoxin Zhang; Zhentao Zhang

    2014-01-01

    Background: Impulsive and compulsive behaviors (ICBs) are a heterogeneous group of conditions that may be caused by long-term dopaminergic replacement therapy (DRT) of Parkinson's disease (PD). The spectrum of ICBs includes dopamine dysregulation syndrome (DDS), punding and impulsive control disorders (ICDs). Contents: We made a detailed review regarding the epidemiology, pathology, clinical characteristics, risk factors, diagnosis as well as treatment of ICBs. Results: The prevalence o...

  20. Prostaglandin E receptor EP1 controls impulsive behavior under stress

    OpenAIRE

    Matsuoka, Yoko; Furuyashiki, Tomoyuki; Yamada, Kiyofumi; Nagai, Taku; Bito, Haruhiko; Tanaka, Yasuhiro; Kitaoka, Shiho; Ushikubi, Fumitaka; Nabeshima, Toshitaka; Narumiya, Shuh

    2005-01-01

    Animals under stress take adaptive actions that may lead to various types of behavioral disinhibition. Such behavioral disinhibition, when expressed excessively and impulsively, can result in harm in individuals and cause a problem in our society. We now show that, under social or environmental stress, mice deficient in prostaglandin E receptor subtype EP1 (Ptger1-/-) manifest behavioral disinhibition, including impulsive aggression with defective social interaction, impaired cliff avoidance,...

  1. Tangent-Impulse Interception for a Hyperbolic Target

    OpenAIRE

    Dongzhe Wang; Gang Zhang; Xibin Cao

    2014-01-01

    The two-body interception problem with an upper-bounded tangent impulse for the interceptor on an elliptic parking orbit to collide with a nonmaneuvering target on a hyperbolic orbit is studied. Firstly, four special initial true anomalies whose velocity vectors are parallel to either of the lines of asymptotes for the target hyperbolic orbit are obtained by using Newton-Raphson method. For different impulse points, the solution-existence ranges of the target true anomaly for any conic transf...

  2. Gigabit impulse radio UWB signal generation and fiber transmission

    DEFF Research Database (Denmark)

    Rodes Lopez, Roberto; Gibbon, Timothy Braidwood; Yu, Xianbin; Guerrero Gonzalez, Neil; Jensen, Jesper Bevensee; Tafur Monroy, Idelfonso

    We demonstrate 3.125 Gb/s photonic impulse radio UWB generation using an uncooled distributed feedback laser. After 50km fiber transmission the signal is recovered without errors using a digital signal processing receiver.......We demonstrate 3.125 Gb/s photonic impulse radio UWB generation using an uncooled distributed feedback laser. After 50km fiber transmission the signal is recovered without errors using a digital signal processing receiver....

  3. Addictions and Personality Traits: Impulsivity and Related Constructs

    OpenAIRE

    Mitchell, Marci R.; Potenza, Marc N.

    2014-01-01

    Behavioral tendencies that might be captured through self-report measures may provide insight into personality features that are associated with substance addictions. Recently, impulsivity and related constructs, such as sensation-seeking, have been examined to help better understand their relationships with addictions. Here, we review recent findings that show links over developmental epochs between addictive behaviors and impulsivity, sensation-seeking, and other constructs that are theoret...

  4. Do Different Facets of Impulsivity Predict Different Types of Aggression?

    OpenAIRE

    Derefinko, Karen; DeWall, C. Nathan; Metze, Amanda V.; Walsh, Erin C.; LYNAM, DONALD R.

    2011-01-01

    The current study examined the relations between impulsivity-related traits (as assessed by the UPPS-P Impulsive Behavior Scale) and aggressive behaviors. Results indicated that UPPS-P Lack of Premeditation and Sensation Seeking were important in predicting general violence. In contrast, UPPS-P Urgency was most useful in predicting intimate partner violence. To further explore relations between intimate partner violence and Urgency, a measure of autonomic response to pleasant and aversive sti...

  5. Reflection impulsivity in binge drinking: behavioural and volumetric correlates.

    Science.gov (United States)

    Banca, Paula; Lange, Iris; Worbe, Yulia; Howell, Nicholas A; Irvine, Michael; Harrison, Neil A; Moutoussis, Michael; Voon, Valerie

    2016-03-01

    The degree to which an individual accumulates evidence prior to making a decision, also known as reflection impulsivity, can be affected in psychiatric disorders. Here, we study decisional impulsivity in binge drinkers, a group at elevated risk for developing alcohol use disorders, comparing two tasks assessing reflection impulsivity and a delay discounting task, hypothesizing impairments in both subtypes of impulsivity. We also assess volumetric correlates of reflection impulsivity focusing on regions previously implicated in functional magnetic resonance imaging studies. Sixty binge drinkers and healthy volunteers were tested using two different information-gathering paradigms: the beads task and the Information Sampling Task (IST). The beads task was analysed using a behavioural approach and a Bayesian model of decision making. Delay discounting was assessed using the Monetary Choice Questionnaire. Regression analyses of primary outcomes were conducted with voxel-based morphometry analyses. Binge drinkers sought less evidence prior to decision in the beads task compared with healthy volunteers in both the behavioural and computational modelling analysis. There were no group differences in the IST or delay discounting task. Greater impulsivity as indexed by lower evidence accumulation in the beads task was associated with smaller dorsolateral prefrontal cortex and inferior parietal volumes. In contrast, greater impulsivity as indexed by lower evidence accumulation in the IST was associated with greater dorsal cingulate and precuneus volumes. Binge drinking is characterized by impaired reflection impulsivity suggesting a deficit in deciding on the basis of future outcomes that are more difficult to represent. These findings emphasize the role of possible therapeutic interventions targeting decision-making deficits. PMID:25678093

  6. Relationship between Impulsivity, Social Media Usage and Loneliness

    OpenAIRE

    Mustafa Savci; Ferda Aysan

    2016-01-01

    The purpose of this study is to examine the relationships between impulsivity, social media usage, and loneliness and to test the structural hypothetical model developed based on the literature. The study was conducted on 307 (164 female, 143 male) university students. Data collection instruments of the study were the Barratt Impulsivity Scale Short Form (BIS-11-SF), Social Media Usage Scale (SMUS), and UCLA Loneliness Scale Short Form (ULS-8). The measurement models of the latent variables w...

  7. Neural mechanisms of impulse control in sexually risky adolescents

    OpenAIRE

    Goldenberg, Diane; Eva H Telzer; Lieberman, Matthew D.; Fuligni, Andrew; Galván, Adriana

    2013-01-01

    The consequences of risky sexual behavior are of public concern. Adolescents contribute disproportionately to negative consequences of risky sexual behavior. However, no research has examined the neural correlates of impulse control and real-world engagement in risky sexual behavior in this population. The aim of the present study was to examine this question. Twenty sexually active adolescents performed an impulse control task during a functional magnetic resonance imaging (fMRI) scan and ri...

  8. Periodicity-based kurtogram for random impulse resistance

    Science.gov (United States)

    Xu, Xiaoqiang; Zhao, Ming; Lin, Jing; Lei, Yaguo

    2015-08-01

    The kurtogram developed from spectral kurtosis has been proven as an efficient tool for extracting the fault impulses in the diagnosis of rolling element bearings and gearboxes. Although the optimal narrowband chosen for demodulation by kurtogram is accurate and effective in experimental environment, this approach is very sensitive to large random impulses that are frequently encountered in industrial applications. The narrowband with maximum kurtosis is always associated with large interferential impulses, rather than the bearing fault. To overcome this limitation, the periodic component to aperiodic component ratio (PAR) is utilized in this article to differentiate the two types of impulses. The novel method named the PAR-based kurtogram focuses on finding the significant frequency band with periodic impulses. The effectiveness of the proposed method is verified by simulations, a test rig of locomotive rolling element bearings, and bearing data from the Case Western Reserve University. The results show that the PAR-based kurtogram improves the robustness to interference from aperiodic impulses significantly, which is very useful for bearing faults diagnosis.

  9. Two clusters of child molesters based on impulsiveness

    Directory of Open Access Journals (Sweden)

    Danilo A. Baltieri

    2015-06-01

    Full Text Available Objective:High impulsiveness is a general problem that affects most criminal offenders and is associated with greater recidivism risk. A cluster analysis of impulsiveness measured by the Barratt Impulsiveness Scale - Version 11 (BIS-11 was performed on a sample of hands-on child molesters.Methods:The sample consisted of 208 child molesters enrolled in two different sectional studies carried out in São Paulo, Brazil. Using three factors from the BIS-11, a k-means cluster analysis was performed using the average silhouette width to determine cluster number. Direct logistic regression was performed to analyze the association of criminological and clinical features with the resulting clusters.Results:Two clusters were delineated. The cluster characterized by higher impulsiveness showed higher scores on the Sexual Screening for Pedophilic Interests (SSPI, Static-99, and Sexual Addiction Screening Test.Conclusions:Given that child molesters are an extremely heterogeneous population, the “number of victims” item of the SSPI should call attention to those offenders with the highest motor, attentional, and non-planning impulsiveness. Our findings could have implications in terms of differences in therapeutic management for these two groups, with the most impulsive cluster benefitting from psychosocial strategies combined with pharmacological interventions.

  10. Impulsivity in sexual offenders – new ideas or back to basics?

    Directory of Open Access Journals (Sweden)

    Aleksandra Krasowska,

    2013-07-01

    Full Text Available Despite the fact that the group of sexual offenders remains a population which is still difficult to study, the results of current research are considered novel and interesting. Surprisingly, the very old descriptions applying to paraphilia, which is considered to be one of the reasons of sexual offences, appear to be accurate, especially in the context of similarities between impulsivity and pathologic sexual behaviors. Notably, the nomenclature concerning impulsivity enables a specific and reasonable description of behaviors associated with sexual offences. Moreover, the results of research studies show that it is the lack of inhibition, not pathologic arousal, which is the most important factor in the pathogenesis of forbidden sexual behaviors. In addition, it has been shown that behavioral manifestations of impulsivity (substance abuse, suicide attempts appear commonly in sexual offenders.Mutual relationships between alcohol drinking, suicide attempts, history of child sexual abuse and sexual offences, in symptomatologic and etiologic aspect, raise a suggestion that all these phenomena may share a common background of poor inhibitory control.

  11. Longitudinal trajectories of sensation seeking, risk taking propensity, and impulsivity across early to middle adolescence.

    Science.gov (United States)

    Collado, Anahi; Felton, Julia W; MacPherson, Laura; Lejuez, C W

    2014-11-01

    Adolescent substance use and abuse show associations with increases in disinhibitory constructs, including sensation seeking, risk taking propensity, and impulsivity. However, the longitudinal trajectories of these constructs from early to middle adolescence remain largely unknown. Thus, the current study examined these developmental trajectories in 277 adolescents (Mage=11.00 at Wave 1), over five consecutive yearly waves. Controlling for age, Hierarchical Linear Modeling analyses showed that sensation seeking increased linearly, whereas risk taking propensity and impulsivity demonstrated curvilinear changes. Specifically, risk taking propensity increased in the first four waves of assessment but did not evidence changes at the last assessment wave. Impulsivity, on the other hand peaked at wave four before subsequently declining. A comparison between females and males and Black and White adolescents suggested that these groups' trajectories were similar. Black adolescents' sensation seeking trajectory differed from adolescents who belonged to the "Other" racial group (i.e., adolescents who neither self-identified as Black or White). Generally, the study findings replicate and extend earlier work indicating that these risk factors increase across early adolescence and begin to level-off during middle adolescence. The importance of understanding the natural course of these core constructs is of great importance for directing future relevant prevention and intervention work. PMID:24566195

  12. Occurrence statistics of magnetic impulsive events

    Directory of Open Access Journals (Sweden)

    T. Moretto

    2004-01-01

    Full Text Available In this study, we perform a statistical investigation of magnetic impulse events identified in the Greenland magnetometer stations through the years 19952001. We focus on occurrence statistics that can be determined reliably with an automatic event identification procedure. Durin the first two years we observed almost 40% more events than in the following years. Season is not a significant factor in event occurrence. Event occurrence peaks near 12:00UT, corresponding to approximately 10:00 magnetic local time (MLT at the west coast of Greenland. More events occur prior to local noon than after. Event days are not distributed evenly. Large amplitude events, particularly, tend to appear on consecutive days. Events are observed at lower latitudes at earlier local times in a way consistent with the projection of the outer magnetospheric boundary into the ionosphere. Event latitude depends on dipole tilt angle in a manner similar to that reported for the cusp. Events occur during intervals of enhanced Kp. The main reason for this is that the events themselves contribute to the Kp index. Events exhibit a preference for high solar wind velocity. In particular, the large amplitude events occur during high-speed streams. A slight preference for lower density and more radial interplanetary magnetic fields, as compared to the nominal solar wind distribution, is also observed. However, both the nominal solar wind and event distribution exhibit large differences from year to year, indicating that events occur under a broad range of conditions.

    Key words. Ionosphere (ionospheric disturbances Magnetospheric physics (magnetosphere-ionosphere interactions; solar wind-magnetosphere interactions

  13. Acoustic radiation force impulse of the liver.

    Science.gov (United States)

    D'Onofrio, Mirko; Crosara, Stefano; De Robertis, Riccardo; Canestrini, Stefano; Demozzi, Emanuele; Gallotti, Anna; Pozzi Mucelli, Roberto

    2013-08-14

    Acoustic radiation force impulse (ARFI) imaging is a new and promising ultrasound-based diagnostic technique that, evaluating the wave propagation speed, allows the assessment of the tissue stiffness. ARFI is implemented in the ultrasound scanner. By short-duration acoustic radiation forces (less than 1 ms), localized displacements are generated in a selected region of interest not requiring any external compression so reducing the operator dependency. The generated wave scan provides qualitative or quantitative (wave velocity values) responses. Several non-invasive methods for assessing the staging of fibrosis are used, in order to avoid liver biopsy. Liver function tests and transient elastography are non-invasive, sensitive and accurate tools for the assessment of liver fibrosis and for the discrimination between cirrhotic and non-cirrhotic liver. Many published studies analyse ARFI performance and feasibility in studying diffuse liver diseases and compare them to other diagnostic imaging modalities such as conventional ultrasonography and transient elastography. Solid focal liver lesions, both benign and malignant, are common findings during abdominal examinations. The accurate characterization and differential diagnosis are important aims of all the imaging modalities available today. Only few papers describe the application of ARFI technology in the study of solid focal liver lesions, with different results. In the present study, the existing literature, to the best of our knowledge, about ARFI application on diffuse and focal liver pathology has been evaluated and results and statistical analyses have been compared, bringing to the conclusion that ARFI can be used in the study of the liver with similar accuracy as transient elastography in diagnosing significant fibrosis or cirrhosis and has got some advantages in respect to transient elastography since it does not require separate equipment, better displays anatomical structures and measurements can be successfully carried out almost in every patient. PMID:23946588

  14. Acoustic radiation force impulse of the liver

    Science.gov (United States)

    D’Onofrio, Mirko; Crosara, Stefano; De Robertis, Riccardo; Canestrini, Stefano; Demozzi, Emanuele; Gallotti, Anna; Pozzi Mucelli, Roberto

    2013-01-01

    Acoustic radiation force impulse (ARFI) imaging is a new and promising ultrasound-based diagnostic technique that, evaluating the wave propagation speed, allows the assessment of the tissue stiffness. ARFI is implemented in the ultrasound scanner. By short-duration acoustic radiation forces (less than 1 ms), localized displacements are generated in a selected region of interest not requiring any external compression so reducing the operator dependency. The generated wave scan provides qualitative or quantitative (wave velocity values) responses. Several non-invasive methods for assessing the staging of fibrosis are used, in order to avoid liver biopsy. Liver function tests and transient elastography are non-invasive, sensitive and accurate tools for the assessment of liver fibrosis and for the discrimination between cirrhotic and non-cirrhotic liver. Many published studies analyse ARFI performance and feasibility in studying diffuse liver diseases and compare them to other diagnostic imaging modalities such as conventional ultrasonography and transient elastography. Solid focal liver lesions, both benign and malignant, are common findings during abdominal examinations. The accurate characterization and differential diagnosis are important aims of all the imaging modalities available today. Only few papers describe the application of ARFI technology in the study of solid focal liver lesions, with different results. In the present study, the existing literature, to the best of our knowledge, about ARFI application on diffuse and focal liver pathology has been evaluated and results and statistical analyses have been compared, bringing to the conclusion that ARFI can be used in the study of the liver with similar accuracy as transient elastography in diagnosing significant fibrosis or cirrhosis and has got some advantages in respect to transient elastography since it does not require separate equipment, better displays anatomical structures and measurements can be successfully carried out almost in every patient. PMID:23946588

  15. Impulsivity and compulsive buying are associated in a non-clinical sample: an evidence for the compulsivity-impulsivity continuum?

    OpenAIRE

    de Paula, Jonas J.; Danielle S. Costa; Flavianne Oliveira; Joana O. Alves; Ldia R. Passos; Malloy-Diniz, Leandro F.

    2015-01-01

    Objective:Compulsive buying is controversial in clinical psychiatry. Although it is defined as an obsessive-compulsive disorder, other personality aspects besides compulsivity are related to compulsive buying. Recent studies suggest that compulsivity and impulsivity might represent a continuum, with several psychiatric disorders lying between these two extremes. In this sense, and following the perspective of dimensional psychiatry, symptoms of impulsivity and compulsivity should correlate ev...

  16. Impulsivity and Reasons for Living Among African American Youth: A Risk-Protection Framework of Suicidal Ideation

    Directory of Open Access Journals (Sweden)

    Temilola K. Salami

    2015-05-01

    Full Text Available This study aims to explore the impact of specific facets of impulsivity as measured by the UPPS Impulsive Behavior Scale (UPPS, as well as reasons for living in predicting suicidal ideation among African American college-aged students. The incremental validity of each facet of the UPPS interacting with reasons for living, a construct meant to buffer against risk for suicide, was explored in a sample of African American students (N = 130; ages 1824. Results revealed significant interactions between reasons for living and two factors of impulsivity, (lack of premeditation and sensation seeking. Higher levels of sensation seeking and lack of premeditation in conjunction with lower reasons for living was associated with increased suicidal ideation. Neither urgency nor (lack of perseverance significantly interacted with reasons for living in association with suicidal ideation. These results suggest including elements of impulsivity, specifically sensation seeking and (lack of premeditation, when screening for suicidal ideation among African American youth. Future investigations should continue to integrate factors of both risk and protection when determining risk for suicide.

  17. Impulsivity and compulsive buying are associated in a non-clinical sample: an evidence for the compulsivity-impulsivity continuum?

    Directory of Open Access Journals (Sweden)

    Jonas J. de Paula

    2015-09-01

    Full Text Available Objective:Compulsive buying is controversial in clinical psychiatry. Although it is defined as an obsessive-compulsive disorder, other personality aspects besides compulsivity are related to compulsive buying. Recent studies suggest that compulsivity and impulsivity might represent a continuum, with several psychiatric disorders lying between these two extremes. In this sense, and following the perspective of dimensional psychiatry, symptoms of impulsivity and compulsivity should correlate even in a non-clinical sample. The present study aims to investigate whether these two traits are associated in a healthy adult sample.Methods:We evaluated 100 adults, with no self-reported psychiatric disorders, using the Barratt Impulsiveness Scale-11 and two scales of compulsive buying.Results:Using multiple linear regressions, we found that impulsivity accounted for about 15% of variance in the compulsive-buying measure.Conclusions:Our results suggest that an association between impulsivity and compulsive buying occurs even in non-clinical samples, evidence that compulsivity and impulsivity might form a continuum and that compulsive buying might be an intermediate condition between these two personality traits.

  18. Impulsivity and Emotional Factors in Obesity: A Preliminary Study

    Directory of Open Access Journals (Sweden)

    Fatma Özlem Orhan

    2012-03-01

    Full Text Available Objective: The aim of this study was to investigate the relationship of obesity with impulsivity and emotional factors. Met­hods: Forty-eight obese participants included in the study were compared with 48 normal-weight controls. The Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I, Eating Attitudes Test (EAT, Beck Depression Scale (BDS, and the Barrat Impulsiveness Scale-11 (BIS-11 were administered to all participants. Re­sults: Forty-eight obese participants were split into two groups: with regard to presence of binge eating disorder - binge eating group (22 subjects - 19 females and 3 males and non-binge eating group (26 subjects - 25 females and 1 males. No difference was detected between the groups in terms of impulsivity scores (p>0.05. Twenty-five of the 48 subjects with obesity were diagnosed with depressive disorder according to the DSM-IV criteria. Eight of the 48 control subjects had depressive disorder. Eating Attitudes Test and Beck Depression Scale scores were statistically significantly higher in the obese group than in the control group (p<0.05. We also compared the impulsivity scores between the depression and non-depression groups where impulsivity scores were found to be significantly higher in the depression group than in the non-depression group (p<0.05. Similarly, in the obese group, impulsivity scores of subjects with more elevated depression scores were significantly higher than those with lower depression scores (p<0.05. Conc­lu­si­on: The foremost finding of this study was determination of a stronger relationship between obesity and emotional traits than the relationship between obesity and impulsivity traits. In the current study, we also observed high impulsivity scores in the depression group. This result was associated more with the relationship between depression and impulsivity than with the relationship between obesity and impulsivity. Further studies with larger samples are required. (Arc­hi­ves of Neu­ropsy­chi­atry 2012; 49: 14-9

  19. Neural circuitry of impulsivity in a cigarette craving paradigm

    Directory of Open Access Journals (Sweden)

    StephanePotvin

    2013-07-01

    Full Text Available Impulsivity has been shown to play a pivotal role in the onset, pattern of consumption, relapse and, most notably, craving of illicit and licit drugs such as cigarette smoking. The goal of this study was to examine the neurobiological influence of trait impulsivity during cue-induced cigarette craving. Thirty-one chronic smokers passively viewed appetitive smoking-related and neutral images while being scanned and reported their feelings of craving. They completed the Barratt Impulsiveness Scale, a measure of trait impulsivity. We conducted functional connectivity analyses using the psycho-physiological interaction method. During the processing of smoking stimuli, participants presented increased activations in the cingulate and prefrontal cortices, as well as in the limbic system. We observed a significant positive relationship between impulsivity scores and reported craving. A negative correlation was observed between the impulsivity score and activity in the posterior cingulate cortex (PCC. The insula, dorsal anterior cingulate cortex (dACC as well as the dorsolateral prefrontal cortex (DLPFC presented a negative connectivity with the PCC. Consistent with the view that the PCC is related to the ability to resist cigarette craving, our results suggest that high impulsive smokers have greater difficulty in controlling their cravings, and that this weakness may be mediated by lower PCC activity. Moreover, we argue that the less PCC activity, the greater the probability of a stronger emotional, physiological and biased attentional response to smoking cues mediated by insula, dACC and DLPFC activity. This is the first study on this topic, and so, results will need to be replicated in both licit and illicit drug abusers. Our findings also highlight a need for more emphasis on the PCC in drug addiction research, as it is one of the most consistently activated regions in fMRI studies examining the neural correlates of cue-induced alcohol, drug and tobacco cravings.

  20. [Heredity and role of serotonin in aggressive impulsive behavior].

    Science.gov (United States)

    Staner, L; Mendlewicz, J

    1998-01-01

    The idea that heredity could influence behaviour, including personality is very old. Until the early 1980s, the evidence for genetic influences on personality derived almost exclusively from twin studies. More recently, studies comparing twins raised together with those raised in different environment confirmed that about 40% of the observed personality variance can be attributable to genetic factors. Since complex behaviours, such as those underlying personality functioning, are likely to be influenced by many genes, a continuum of genetic risk underlying behavioural dimensions that extend from normal to abnormal behaviour has been hypothesized. Behaviours related to aggressive impulses regulation could delineate a biologically anchored model of dispositions to both normal and pathological functioning: these behaviours are identified in animal species where they are genetically transmitted, and a growing body of evidence suggests that disturbances in the regulation of aggressive impulses could belong to a behavioural dimension (disturbances of impulse control) linked to serotonin. Theorists involved in modelling personality according to psychobiologic basis agree with the idea of an inhibitory function of serotonin on impulsive behaviour and recognise that the way individuals control their impulses could underlie a basic psychobiological personality dimension. According to genotypes and to environmental factors, these serotonin mediated behaviours may be diversely expressed varying from minor personality peculiarities (characterised by impulsivity, hostility, irritability, psychopathic deviance, excessive violence or by more clear-cut personality dysfunctioning such as antisocial, borderline, narcissistic and histrionic personality traits or disorders) to major psychiatric disturbances (suicidal behaviour, overt aggressive behaviour, intermittent explosive disorder, pathological gambling, pyromania, bulimia and some type of substance or alcohol abuse). Finally, recent molecular genetic studies have demonstrated that genes encoding some key proteins involved in serotonin transmission could present some polymorphism in relation with impulsive-aggressive behaviours. PMID:9809241

  1. Stochastic Particle Acceleration in Impulsive Solar Flares

    Science.gov (United States)

    Miller, James A.

    2001-01-01

    The acceleration of a huge number of electrons and ions to relativistic energies over timescales ranging from several seconds to several tens of seconds is the fundamental problem in high-energy solar physics. The cascading turbulence model we have developed has been shown previously (e.g., Miller 2000; Miller & Roberts 1995; Miner, LaRosa, & Moore 1996) to account for all the bulk features (such as acceleration timescales, fluxes, total number of energetic particles, and maximum energies) of electron and proton acceleration in impulsive solar flares. While the simulation of this acceleration process is involved, the essential idea of the model is quite simple, and consists of just a few parts: 1. During the primary flare energy release phase, we assume that low-amplitude MHD Alfven and fast mode waves are excited at long wavelengths, say comparable to the size of the event (although the results are actually insensitive to this initial wavelength). While an assumption, this appears reasonable in light of the likely highly turbulent nature of the flare. 2. These waves then cascade in a Kolmogorov-like fashion to smaller wavelengths (e.g., Verma et al. 1996), forming a power-law spectral density in wavenumber space through the inertial range. 3. When the mean wavenumber of the fast mode waves has increased sufficiently, the transit-time acceleration rate (Miller 1997) for superAlfvenic electrons can overcome Coulomb energy losses, and these electrons are accelerated out of the thermal distribution and to relativistic energies (Miller et al. 1996). As the Alfven waves cascade to higher wavenumbers, they can cyclotron resonate with progressively lower energy protons. Eventually, they will resonate with protons in the tail of the thermal distribution, which will then be accelerated to relativistic energies as well (Miller & Roberts 1995). Hence, both ions and electrons are stochastically accelerated, albeit by different mechanisms and different waves. 4. When the protons become superAlfvenic (above about 1 MeV/nucleon), they too can suffer transit-time acceleration by the fast mode waves and will receive an extra acceleration "kick." The basic overall objective of this 1 year effort was to construct a spatially-dependent version of this acceleration model and this has been realized.

  2. Impulse Volt-Time Characteristics of Oil and OIP Insulation

    Directory of Open Access Journals (Sweden)

    S. Venkatesan

    2005-01-01

    Full Text Available Estimation of insulation strength of transformer oil and Oil Impregnated Paper (OIP insulation, which constitutes major portion of insulation in power transformer, is an important task. Also, it is often necessary to evaluate the breakdown strength of oil and OIP under non-standard impulse voltages, since the oil and OIP insulation is subjected to non-standard waveshapes between inter-disc and inter-turn insulation. This necessitates for a generalized model to estimate the insulation strength of it. In this study impulse strength of transformer oil and OIP insulation have been extensively analysed for very small electrode gap distances ranging from 0.1 to 2.5 mm, which represents the inter-turn and inter-disc thickness of the insulation. The statistical mean volt-time characteristics for uniform and highly non-uniform electrode configurations are obtained experimentally for few gap distances. A Hyperbolic model is developed based on the Disruptive Effect (DE model parameters, namely onset voltage (Uo and Critical Disruptive Effect Area (DE * to predict the volt-time characteristics. The DE parameters are also utilised to predict the impulse breakdown characteristics of oil and OIP under non-standard impulse voltages of standard and unidirectional oscillatory impulse waveshapes for all the gap distances and the errors are found to be less than 10%.

  3. Prediction of BMI by impulsivity, eating behavior and activity level

    Directory of Open Access Journals (Sweden)

    Jiang Xiaxia

    2016-01-01

    Full Text Available Objective: Discuss the relationship between the impulsivity, eating behavior and activity level and the body mass index (BMI. Method: Test 147 female college students with the impulsivity questionnaire (BIS-11 and BIS/BAS, Dutch Eating Behavior Questionnaire (DBEQ, Sitting Time Scale (STS and Exercising Time Scale (ETS. Results: (1 The correlation analysis indicates that BMI and impulsivity (r = 0.43 and 0.52 have a significant positive correlation with the sitting time (r = 0.61 and a significant negative correlation with the activity level (r= ?0.49. (2 The path analysis indicates that the reward sensitivity directly affects BMI and indirectly affects BMI through the activity level as well; the eating behavior has an insignificantly direct impact on BMI, because its impact is generated by the intermediary role of induced diet. Conclusion: (1 The impulsivity, eating behavior and activity level are closely related to BMI; (2 the activity level, sitting time and induced diet play an intermediary role between the impulsivity and BMI.

  4. Solar flare impulsive phase emission observed with SDO/EVE

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, Michael B.; Milligan, Ryan O.; Mathioudakis, Mihalis; Keenan, Francis P., E-mail: mkennedy29@qub.ac.uk [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, University Road, Belfast BT7 1NN (United Kingdom)

    2013-12-10

    Differential emission measures (DEMs) during the impulsive phase of solar flares were constructed using observations from the EUV Variability Experiment (EVE) and the Markov-Chain Monte Carlo method. Emission lines from ions formed over the temperature range log T{sub e} = 5.8-7.2 allow the evolution of the DEM to be studied over a wide temperature range at 10 s cadence. The technique was applied to several M- and X-class flares, where impulsive phase EUV emission is observable in the disk-integrated EVE spectra from emission lines formed up to 3-4 MK and we use spatially unresolved EVE observations to infer the thermal structure of the emitting region. For the nine events studied, the DEMs exhibited a two-component distribution during the impulsive phase, a low-temperature component with peak temperature of 1-2 MK, and a broad high-temperature component from 7 to 30 MK. A bimodal high-temperature component is also found for several events, with peaks at 8 and 25 MK during the impulsive phase. The origin of the emission was verified using Atmospheric Imaging Assembly images to be the flare ribbons and footpoints, indicating that the constructed DEMs represent the spatially average thermal structure of the chromospheric flare emission during the impulsive phase.

  5. Solar flare impulsive phase emission observed with SDO/EVE

    International Nuclear Information System (INIS)

    Differential emission measures (DEMs) during the impulsive phase of solar flares were constructed using observations from the EUV Variability Experiment (EVE) and the Markov-Chain Monte Carlo method. Emission lines from ions formed over the temperature range log Te = 5.8-7.2 allow the evolution of the DEM to be studied over a wide temperature range at 10 s cadence. The technique was applied to several M- and X-class flares, where impulsive phase EUV emission is observable in the disk-integrated EVE spectra from emission lines formed up to 3-4 MK and we use spatially unresolved EVE observations to infer the thermal structure of the emitting region. For the nine events studied, the DEMs exhibited a two-component distribution during the impulsive phase, a low-temperature component with peak temperature of 1-2 MK, and a broad high-temperature component from 7 to 30 MK. A bimodal high-temperature component is also found for several events, with peaks at 8 and 25 MK during the impulsive phase. The origin of the emission was verified using Atmospheric Imaging Assembly images to be the flare ribbons and footpoints, indicating that the constructed DEMs represent the spatially average thermal structure of the chromospheric flare emission during the impulsive phase.

  6. Solar Flare Impulsive Phase Emission Observed with SDO/EVE

    Science.gov (United States)

    Kennedy, Michael B.; Milligan, Ryan O.; Mathioudakis, Mihalis; Keenan, Francis P.

    2013-12-01

    Differential emission measures (DEMs) during the impulsive phase of solar flares were constructed using observations from the EUV Variability Experiment (EVE) and the Markov-Chain Monte Carlo method. Emission lines from ions formed over the temperature range log Te = 5.8-7.2 allow the evolution of the DEM to be studied over a wide temperature range at 10 s cadence. The technique was applied to several M- and X-class flares, where impulsive phase EUV emission is observable in the disk-integrated EVE spectra from emission lines formed up to 3-4 MK and we use spatially unresolved EVE observations to infer the thermal structure of the emitting region. For the nine events studied, the DEMs exhibited a two-component distribution during the impulsive phase, a low-temperature component with peak temperature of 1-2 MK, and a broad high-temperature component from 7 to 30 MK. A bimodal high-temperature component is also found for several events, with peaks at 8 and 25 MK during the impulsive phase. The origin of the emission was verified using Atmospheric Imaging Assembly images to be the flare ribbons and footpoints, indicating that the constructed DEMs represent the spatially average thermal structure of the chromospheric flare emission during the impulsive phase.

  7. The Impact of Visual Merchandising on Consumer Impulse Buying Behavior

    Directory of Open Access Journals (Sweden)

    Khurram L. Bhatti

    2014-05-01

    Full Text Available In present Post-Modern Era, the competitive situation in the business is characterized by a cut throat competition, which subsequently results in companies and retailers to pay almost anything for undifferentiated merchandising. This merchandising tool is being used by today’s retailer to distinguish him from other competitors, to be prominent in the market and become a source of attraction for the customers. A few researchers contribute in this field by exploring the reasons which causes the customers impulsive buying, but still there is more to be determined. Purpose of this study is to identify the relation between the consumer impulsive buying and visual merchandising on buying behavior of customers. This study was based on primary data in the form of a questioner. A total of 350 questioners were floated in different consumer outlets (super marts and self-service stores of Rawalpindi, Pakistan out of which 344 questioners were completed and received. Defined four hypotheses were window display, forum display, floor merchandising and shop brand name. These hypotheses were tested for regression analysis by using Statistical Packages for Social Sciences (SPSS software. It was found that window display, forum display, floor merchandising and shop brand name (independent variables are significantly associated to consumer impulse buying behavior (dependent variable. Hence, forum display is negatively related to consumer impulse buying and window display; however, floor merchandising and shop brand name are positively related to consumer impulse buying behavior.

  8. Characteristic Risk Factors Associated with Planned versus Impulsive Suicide Attempters

    Science.gov (United States)

    Kim, Jaeha; Lee, Kang-Sook; Kim, Dai Jin; Hong, Seung-Chul; Choi, Kyoung Ho; Oh, Youngmin; Wang, Sheng-Min; Lee, Hae-Kook; Kweon, Yong-Sil; Lee, Chung Tai; Lee, Kyoung-Uk

    2015-01-01

    Objective The present study aimed to investigate predictors for planned suicide attempters. Methods This study included 1,003 patients who attempted suicide and visited emergency department. They were divided into two groups, planned suicide attempters (SAs; n=133 [13.3%]) and impulsive SAs (n=870, [86.7%]), and the demographic variables, clinical characteristics, factors related to suicide, and psychiatric resources of the groups were compared. Results Major depressive disorder and substance use disorders were more common among planned SAs than among impulsive SAs. Additionally, the planned SAs were older, more likely to be divorced, separated or widowed, and more likely to have comorbid medical illnesses, severe depression, higher suicidality, and self-blaming tendencies than the impulsive SAs. Financial problems and physical illnesses were more common in planned SAs but interpersonal conflicts were more frequent in impulsive SAs. Planned SAs had fewer previous suicide attempts but these were more serious suicide attempts. The presence of the hope to die, a written will, and suicidal ideation of a repetitive, intense, and continuous nature were predictive of planned SAs. Conclusion The present findings demonstrated that planned SAs had more severe psychopathology and medical illnesses than impulsive SAs. Therefore, screening for depression, substance use disorders, and suicidal plans among old and medically ill patients may be important for preventing suicide attempts. PMID:26598591

  9. Vibration testing based on impulse response excited by laser ablation

    Science.gov (United States)

    Kajiwara, Itsuro; Hosoya, Naoki

    2011-10-01

    This paper proposes an innovative vibration testing method based on impulse response excited by laser ablation. In conventional vibration testing using an impulse hammer, high-frequency elements of over tens of kilohertz are barely present in the excitation force. A pulsed high-power YAG laser is used in this study for producing an ideal impulse force on a structural surface. Illuminating a point on a metal with the well-focused YAG laser, laser ablation is caused by generation of plasma on the metal. As a result, an ideal impulse excitation force generated by laser ablation is applied to the point on the structure. Therefore, it is possible to measure high-frequency FRFs due to the laser excitation. A water droplet overlay on the metal is used to adjust the force magnitude of laser excitation. An aluminum block that has nine natural frequencies below 40 kHz is employed as a test piece. The validity of the proposed method is verified by comparing the FRFs of the block obtained by the laser excitation, impulse hammer, and finite element analysis. Furthermore, the relationship between accuracy of FRF measurements and sensitivity of sensors is investigated.

  10. Modulating presence and impulsiveness by external stimulation of the brain

    Directory of Open Access Journals (Sweden)

    Baumgartner Thomas

    2008-08-01

    Full Text Available Abstract Background "The feeling of being there" is one possible way to describe the phenomenon of feeling present in a virtual environment and to act as if this environment is real. One brain area, which is hypothesized to be critically involved in modulating this feeling (also called presence is the dorso-lateral prefrontal cortex (dlPFC, an area also associated with the control of impulsive behavior. Methods In our experiment we applied transcranial direct current stimulation (tDCS to the right dlPFC in order to modulate the experience of presence while watching a virtual roller coaster ride. During the ride we also registered electro-dermal activity. Subjects also performed a test measuring impulsiveness and answered a questionnaire about their presence feeling while they were exposed to the virtual roller coaster scenario. Results Application of cathodal tDCS to the right dlPFC while subjects were exposed to a virtual roller coaster scenario modulates the electrodermal response to the virtual reality stimulus. In addition, measures reflecting impulsiveness were also modulated by application of cathodal tDCS to the right dlPFC. Conclusion Modulating the activation with the right dlPFC results in substantial changes in responses of the vegetative nervous system and changed impulsiveness. The effects can be explained by theories discussing the top-down influence of the right dlPFC on the "impulsive system".

  11. Dysfunctional inhibitory control and impulsivity in Internet addiction.

    Science.gov (United States)

    Choi, Jung-Seok; Park, Su Mi; Roh, Myoung-Sun; Lee, Jun-Young; Park, Chan-Bin; Hwang, Jae Yeon; Gwak, Ah Reum; Jung, Hee Yeon

    2014-02-28

    The purpose of this study was to explore a psychological profile of Internet addiction (IA) considering impulsivity as a key personality trait and as a key component of neuropsychological functioning. Twenty three subjects with IA (Young's Internet Addiction Test scores=70 or more) and 24 sex-, age-, and intelligence-matched healthy controls were enrolled. Participants filled out a questionnaire about trait impulsivity, the Trait Characteristic Inventory, depression, and anxiety. Next, we administered traditional neuropsychological tests including the Stroop et al. and computerized neuropsychological tests using the Cambridge Neuropsychological Test Automated Battery. The IA group exhibited more trait impulsivity than the healthy control group. They also scored higher for novelty seeking and harm avoidance. The IA group performed more poorly than the healthy control group in a computerized stop signal test, a test for inhibitory function and impulsivity; no group differences appeared for other neuropsychological tests. The IA group also scored higher for depression and anxiety, and lower for self-directedness and cooperativeness. In conclusion, individuals with IA exhibited impulsivity as a core personality trait and in their neuropsychological functioning. PMID:24370334

  12. Impulsive synchronization of chaotic Lur'e systems via partial states

    International Nuclear Information System (INIS)

    In this Letter, the problem of impulsive synchronization of two identical Lur'e systems via partial states is studied. The problem arises in the situation when only partial states of the driven systems are available. By using the method of the variation of parameters for linear impulsive systems and some analysis technique, a sufficient condition for the existence of the impulsive control law for synchronization via partial states is derived. The sufficient condition is given in terms of linear matrix inequalities concerning the interconnection matrices. By using this result, we propose a new impulsive synchronization scheme for a class of Lur'e systems. The new impulsive synchronization scheme only exerts the impulsive input on partial states of the driven system and is characterized by a set of conditions related to the impulsive interval bound, the impulsive magnitude and a coupling condition between them. The proposed impulsive synchronization method is illustrated through Chua's circuit

  13. Two impulse trajectory optimization for the RAE-B orbit trim problem

    Science.gov (United States)

    Payne, M. H.; Pines, S.; Horsewood, J. L.

    1972-01-01

    The results are reported of work on an appropriate approach to the solution of the optimum two-impulse transfer problem between orbits of specified inclination. The task included a literature search to identify the current state of the art and a definition of the suggested approach for the specific application of a lunar orbit trim. The applications of the results to the problem are included. The formulation for a computer program developed under this task following a more conventional approach is also included.

  14. Detection and Estimation of Arrivals in Room Impulse Responses by Greedy Sparse Approximation

    DEFF Research Database (Denmark)

    Sturm, Bob L.; Defrance, Guillaume

    We investigate the use of greedy sparse approximation for facilitating the time-domain analysis of room impulse responses (RIRs), specifically locating the times and amplitudes of arrivals to not long after the upper bound of the ``mixing time,'' i.e., the time after which there exists in theory ...... the performance of each estimator using dynamic time warping to optimally pair estimated and true arrivals. We find OMP significantly outperforms MP in estimating both the arrival times and amplitudes, and having fewer erroneous and duplicated arrivals....

  15. Oil and the U.S. Macroeconomy: A Reinvestigation Using Rolling Impulse Responses

    OpenAIRE

    Marc Gronwald

    2012-01-01

    This paper investigates the role of extreme oil price increases in empirical studies of the macroeconomics of oil prices. The innovative approach of rolling impulse responses is applied and data on both the aggregate and the industry-level is considered. The results show that the first oil crisis drives long-run results and superimposes both subsample and industry-specifics. Furthermore, there is evidence that the non-occurrence of large oil shocks after the mid1980s is an important explanati...

  16. Frontotemporal correlates of impulsivity and machine learning in retired professional athletes with a history of multiple concussions.

    Science.gov (United States)

    Goswami, R; Dufort, P; Tartaglia, M C; Green, R E; Crawley, A; Tator, C H; Wennberg, R; Mikulis, D J; Keightley, M; Davis, Karen D

    2016-05-01

    The frontotemporal cortical network is associated with behaviours such as impulsivity and aggression. The health of the uncinate fasciculus (UF) that connects the orbitofrontal cortex (OFC) with the anterior temporal lobe (ATL) may be a crucial determinant of behavioural regulation. Behavioural changes can emerge after repeated concussion and thus we used MRI to examine the UF and connected gray matter as it relates to impulsivity and aggression in retired professional football players who had sustained multiple concussions. Behaviourally, athletes had faster reaction times and an increased error rate on a go/no-go task, and increased aggression and mania compared to controls. MRI revealed that the athletes had (1) cortical thinning of the ATL, (2) negative correlations of OFC thickness with aggression and task errors, indicative of impulsivity, (3) negative correlations of UF axial diffusivity with error rates and aggression, and (4) elevated resting-state functional connectivity between the ATL and OFC. Using machine learning, we found that UF diffusion imaging differentiates athletes from healthy controls with significant classifiers based on UF mean and radial diffusivity showing 79-84 % sensitivity and specificity, and 0.8 areas under the ROC curves. The spatial pattern of classifier weights revealed hot spots at the orbitofrontal and temporal ends of the UF. These data implicate the UF system in the pathological outcomes of repeated concussion as they relate to impulsive behaviour. Furthermore, a support vector machine has potential utility in the general assessment and diagnosis of brain abnormalities following concussion. PMID:25721800

  17. IMPULSES FOR THE POLICY OF EDUCATION TOWARDS THE KNOWLEDGE SOCIETY

    Directory of Open Access Journals (Sweden)

    Antalová Mária

    2014-12-01

    Full Text Available Shaping the knowledge society has become a priority for all the educational policies in member countries of the European Union. Within it, it is a specific quality of life based on people's ability to create value intangible nature, which may take the form of ideas, inventions or solutions of socio-economic character. A knowledge worker becomes the core workforce of the company. This worker works in a team, cooperates with individual members as well as with the group, develops ideas and actively shares knowledge. The way he works considerably varies as well as tools he uses at work. Our purpose is to identify the future competency model for new qualified workforce, which could be applicable for the educational policy, concretely for innovation of the educational and job standards In this paper we apply the theoretical analysis aimed at identifying the knowledge worker specifying the set of professional competencies in frame of 4 partial models, which are: personal competence, individual competence, social competence and societal competence. Through primary analysis we obtained information about preferences of his abilities, needed for changes in the educational system. The aim of this paper is to identify the basic characteristics of the knowledge worker and propose the competency model focusing on the personal, individual, social, and societal competence with its verification and proposal for improving the education standard. The result or our paper present suggest of the competency model of the knowledge worker, which would allow his definition on macro and micro level as well as identification new impulses for the educational policy. Fulfilment of the objective relates to the demanding requirements for qualified workforce in the knowledge society, from which is expected to more specialized knowledge, skills and work habits that would facilitate and promote mobility on the national and international level.

  18. An approach to remove impulse noise from a corrupted image

    International Nuclear Information System (INIS)

    In this paper, we propose an efficient approach for detecting the impulse noise from corrupted images. This method is based on the principle that the feature of the digital image is usually local correlation and the feature of the impulse noise is usually located near one of the two ends of the image’s maximum and minimum gray values. After the noisy pixel has been detected by the proposed detector, a modified version of the mean filter is proposed to remove the detected impulse noise. Experimental results show that the implementation of the proposed method is simple, and it has better performance than comparison filters with regard to effective noise suppression and preservation of detail, especially when the noise ratio is very high. (paper)

  19. Deconvolution of impulse response by the truncated singular value decomposition

    Science.gov (United States)

    Cha, Hao; Dai, Mingzhen

    1992-12-01

    The impulse response of the target plays a very important part in the target identification. However, the impulse response of an electromagnetic system can be obtained through solving the convolution problem. In this paper, the ill-posed problem is solved directly in the time domain by the truncated singular value decomposition (TSVD) method. The less singular values which cause the problem to be ill-posed are discarded, so that the deconvolution problem is changed into a well-posed problem. The impulse response of a sphere is used to make simulations. The results show that the TSVD algorithm can improve the result of the deconvolution by about 10 dB (SNR) compared with the conventional conjugated gradient method.

  20. Impulse-excited pulsations during the July 29, 1977 event

    International Nuclear Information System (INIS)

    The propagation of a geomagnetic sudden impulse (si) and the magnetic field pulsations excited by it in the magnetosphere is traced from the bow shock in the solar wind, through the magnetosphere, to the ground. Within the magnetosphere the impulse appears as a compressive magnetohydrodynamic (MHD) impulse that travels rapidly (approx.1500 km/s) tailward. A resonant oscillation observed both in space and on the ground is excited near geostationary orbit. The effect of the si is enhanced by a factor of at least 5 on the ground near the geomagnetic equator. We suggest that discontinuities in the solar wind may be a more important source of exciting dayside pulsations than has been commonly assumed

  1. Application of E^p-Stability to Impulsive Financial Model

    Directory of Open Access Journals (Sweden)

    Sam Olatunji Ale

    2013-07-01

    Full Text Available In this paper, we consider an impulsive stochastic model for an investment with production and saving profiles. The conditions for financial growth for the investment are investigated under impulsive action and results are obtained using the quantitative and Ep stability methods. The impulsive stochastic differential equation considered is assumed to be driven by a process with jump and non-linear gestation properties. One of the results established shows that, in the long run, it is impossible for a financial investment to grow or dominates the prescribed average financial investment but has a threshold value for which the investment cannot grow beyond. It is also established that an $E^{p}-$ stable investment vector can be found which allows financial growth but this vector must be constrained to be in a given invariant set:It is advisable for the saving and depreciation to satisfy certain growth rates for proper income and investment growths.

  2. [Age-related factors of psychopathology of impulse control disorders].

    Science.gov (United States)

    Shiurkute, A

    1999-01-01

    15 children and adolescents with impulse control disorders (mean age 12.9 years) were examined. These disorders were presented as dromomania, kleptomania, aggressive-sadistic actions, tricholillomania, pyromania; a combination of different types was observed in some cases. Schizophrenia was diagnosed in 7 cases, affective disorders--in 8 patients. Independently of the nosologic unity of the disease, development of the impulse control disorders took place in affective disorders which manifested either by monopolar course (depression) (11 cases), or by bypolar attacks with unclear outlines of the phases (4 patients). Psychopathology of impulse control disorders in children and juveniles was analogous to that of the adults, however, their structure wasn't so complex and development of the phases wasn't so clear. PMID:11530454

  3. Research of Two Different Impulsive Faults of Rolling Element Bearing

    International Nuclear Information System (INIS)

    Fans and pumps are key machines in process industries such as petrochemical and petroleum industries. Their faults can be catastrophic and result in costly downtime. Bearing fault is almost the most common fault of fans and pumps as rolling element bearings are widely used in these machines. Hence, condition monitoring and diagnosis of bearings are important. Two different impulsive faults of bearings have been observed and studied in previous research. The first fault presents very clear impulsive symptom in envelope spectrum, but the bearing can work for a long time. The other fault shows relatively indistinct symptom, but the bearing will break down in a short time. To overcome the problems of inaccurate diagnosis, a combinational approach based on an impulsive energy indicator and traditional enveloping analysis is proposed in this paper. This approach discriminate these two faults well and can support the maintenance decision for the machines with rolling element bearings.

  4. Fuzzy modelling and impulsive control of the hyperchaotic Lü system

    International Nuclear Information System (INIS)

    This paper presents a novel approach to hyperchaos control of hyperchaotic systems based on impulsive control and the Takagi–Sugeno (T–S) fuzzy model. In this study, the hyperchaotic Lü system is exactly represented by the T–S fuzzy model and an impulsive control framework is proposed for stabilizing the hyperchaotic Lü system, which is also suitable for classes of T–S fuzzy hyperchaotic systems, such as the hyperchaotic Rössler, Chen, Chua systems and so on. Sufficient conditions for achieving stability in impulsive T–S fuzzy hyperchaotic systems are derived by using Lyapunov stability theory in the form of the linear matrix inequality, and are less conservative in comparison with existing results. Numerical simulations are given to demonstrate the effectiveness of the proposed method

  5. Fuzzy modelling and impulsive control of the hyperchaotic Lü system

    Science.gov (United States)

    Zhang, Xiao-Hong; Li, Dong

    2009-05-01

    This paper presents a novel approach to hyperchaos control of hyperchaotic systems based on impulsive control and the Takagi-Sugeno (T-S) fuzzy model. In this study, the hyperchaotic Lü system is exactly represented by the T-S fuzzy model and an impulsive control framework is proposed for stabilizing the hyperchaotic Lü system, which is also suitable for classes of T-S fuzzy hyperchaotic systems, such as the hyperchaotic Rössler, Chen, Chua systems and so on. Sufficient conditions for achieving stability in impulsive T-S fuzzy hyperchaotic systems are derived by using Lyapunov stability theory in the form of the linear matrix inequality, and are less conservative in comparison with existing results. Numerical simulations are given to demonstrate the effectiveness of the proposed method.

  6. Do different facets of impulsivity predict different types of aggression?

    Science.gov (United States)

    Derefinko, Karen; DeWall, C Nathan; Metze, Amanda V; Walsh, Erin C; Lynam, Donald R

    2011-01-01

    This study examined the relations between impulsivity-related traits (as assessed by the UPPS-P Impulsive Behavior Scale) and aggressive behaviors. Results indicated that UPPS-P Lack of Premeditation and Sensation Seeking were important in predicting general violence. In contrast, UPPS-P Urgency was most useful in predicting intimate partner violence. To further explore relations between intimate partner violence and Urgency, a measure of autonomic response to pleasant and aversive stimuli and facets of Neuroticism from the NEO PI-R were used as control variables. Autonomic responsivity was correlated with intimate partner violence at the zero-order level, and predicted significant variance in intimate partner violence in regression equations. However, UPPS-P Urgency was able to account for unique variance in intimate partner violence, above and beyond measures of Neuroticism and arousal. Implications regarding the use of a multifaceted conceptualization of impulsivity in the prediction of different types of violent behavior are discussed. PMID:21259270

  7. Dynamic Behaviour of Tension Leg Platform under Impulsive Loading

    Directory of Open Access Journals (Sweden)

    N. A. Siddiqui

    2003-04-01

    Full Text Available In the literature on dynamics of tension leg platforms (TLPs, the effect offrequently occurring environmental forces, such as those arising due to wave, wind, current, tide, etc. has given the due consideration. However, less probable forces, such as that arising due to collision ofship with iceberg or any huge sea creature, etc., have not been considered in the study. Such small duration impact forces, usually termed as impulsive forces, may take four possible shapes: (i rectangular, (ii sinusoidal, (iii triangular, and (iv half-triangular. In the present study, response ofTLP has been obtained for all these four shaped impulsive forces. The result ofthe analyses shows that there is a dramatic change in surge, heave, and yaw responses of TLP due to such forces. In addition, a comparative study to find the most influencing impulsive force out of these four has also been conducted.

  8. Four factors of impulsivity differentiate antisocial and borderline personality disorders.

    Science.gov (United States)

    DeShong, Hilary L; Kurtz, John E

    2013-04-01

    Impulsivity is a shared criterion for the diagnosis of antisocial and borderline personality disorders, and this link may account for the high comorbidity rates between the two disorders. The current study aimed to differentiate between borderline and antisocial personality disorders using the four factors of impulsivity identified by Whiteside and Lynam (2001). Five hundred thirty-six undergraduate participants completed the personality assessment inventory (PAI; Morey, 1991) to assess borderline and antisocial personality features and the NEO personality inventory, third edition (NEO-PI-3; McCrae & Costa, 2010) to assess the four factors of impulsivity. Results indicate that negative urgency and lack of perseverance were significantly and uniquely related to borderline features, while sensation seeking and lack of premeditation were significantly and uniquely related to antisocial features. The implications of these results for improved differential diagnosis are discussed. PMID:23514180

  9. Impulse Noise Removal from Medical Images Using Fuzzy Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Anisha K K

    2011-12-01

    Full Text Available Medical images are analyzed for diagnosis of various diseases. But, they are susceptible to impulse noise. Noise removal can be done much more efficiently by a combination of image filters or a composite filter,than by a single image filter. Determining the appropriate filter combination is a difficult task. In this paper, we propose a technique that uses Fuzzy Genetic Algorithm to find the optimal composite filters for removing all types of impulse noise from medical images. Here, a Fuzzy Rule Base is used to adaptively change the crossover probability of the Genetic Algorithm used to determine the optimal composite filters.The results of simulations performed on a set of standard test images for a wide range of noise corruption levels shows that the proposed method outperforms standard procedures for impulse noise removal bothvisually and in terms of performance measures such as PSNR, IQI and Tenengrad values.

  10. IMPULSE NOISE REMOVAL FROM MEDICAL IMAGES USING FUZZY GENETIC ALGORITHM

    Directory of Open Access Journals (Sweden)

    Anisha K K

    2011-11-01

    Full Text Available Medical images are analyzed for diagnosis of various diseases. But, they are susceptible to impulse noise. Noise removal can be done much more efficiently by a combination of image filters or a composite filter, than by a single image filter. Determining the appropriate filter combination is a difficult task. In this paper, we propose a technique that uses Fuzzy Genetic Algorithm to find the optimal composite filters for removing all types of impulse noise from medical images. Here, a Fuzzy Rule Base is used to adaptively change the crossover probability of the Genetic Algorithm used to determine the optimal composite filters.The results of simulations performed on a set of standard test images for a wide range of noise corruption levels shows that the proposed method outperforms standard procedures for impulse noise removal both visually and in terms of performance measures such as PSNR, IQI and Tenengrad values.

  11. A new approach to calculating spatial impulse responses

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    Using linear acoustics the emitted and scattered ultrasound field can be found by using spatial impulse responses as developed by Tupholme (1969) and Stepanishen (1971). The impulse response is calculated by the Rayleigh integral by summing the spherical waves emitted from all of the aperture...... surface. The evaluation of the integral is cumbersome and quite involved for different aperture geometries. This paper re-investigates the problem and shows that the field can be found from the crossings between the boundary of the aperture and a spherical wave emitted from the field point onto the plane...... of the emitting aperture. Summing the angles of the arcs within the aperture readily yields the spatial impulse response for a point in space. The approach makes is possible to make very general calculation routines for arbitrary, flat apertures in which the outline of the aperture is either...

  12. Neural mechanisms of impulse control in sexually risky adolescents.

    Science.gov (United States)

    Goldenberg, Diane; Telzer, Eva H; Lieberman, Matthew D; Fuligni, Andrew; Galván, Adriana

    2013-10-01

    The consequences of risky sexual behavior are of public concern. Adolescents contribute disproportionately to negative consequences of risky sexual behavior. However, no research has examined the neural correlates of impulse control and real-world engagement in risky sexual behavior in this population. The aim of the present study was to examine this question. Twenty sexually active adolescents performed an impulse control task during a functional magnetic resonance imaging (fMRI) scan and risky sexual behaviors were assessed through self-report. Sexual riskiness ratings were negatively associated with activation in the prefrontal cortex during response inhibition. These results suggest that diminished engagement of impulse control circuitry may contribute to sexual riskiness in adolescents. PMID:23835204

  13. FLANN Detector Based Filtering of Images Corrupted by Impulse Noise

    Directory of Open Access Journals (Sweden)

    Banshidhar Majhi

    2005-01-01

    Full Text Available We present a novel non-linear scheme for image restoration based on neuro-detector using Functional Link Artificial Neural Network (FLANN followed by an improved spatial filter. The method is applied to images corrupted by impulse noise with varying strengths and different noise probability. The neural detector is based on the concept of training or learning by examples. When trained properly, the detector used to detect impulse noise in any image degraded by impulse noise. Hence, the method is suitable for real time image restoration applications. The simulated results obtained from the proposed scheme outperforms existing approaches are highly satisfactory and it outperforms the earlier suggested methods in terms of residual NSR in restored images.

  14. The Impulse Response of an Exponential Assembly

    International Nuclear Information System (INIS)

    A spatial-dependent transfer function of an exponential assembly with rectangular geometry and the neutron source located at the origin in the middle of one side has been derived using diffusion theory and the usual approximations. If the end correction factor is neglected, the result G (x, y, z, s) = (Δϕ(x, y, z, s))/ΔS (o, o, o, o, s) = 2/abD ∞Σm=1∞Σn=1 1/(ρmn(s) cos (mπx)/a cos (nπy)/b e-ρmn(s)Z (1) where ρmn(s) = [s/(VD) + B2⊥mn - B2m]1/2 = [s/VD - γ2mn]1/2 (2) The inverse Laplace transform of Eq. (1) gives the spatial dependent impulse response function (Green's function) to be g (x, y, z, t) = 2/ab √v/πD 1/√t e-z2/4VDt∞Σm=1∞Σn=1 cos mπx/a cos nπy/b e-VDγ2mnt (3) If only the terms of Eq. (3) outside the double summation are considered (i.e. multiplicative and leakage effects are neglected) the result is 2/ab √V/πD 1/√t e-z2/4VDt = 4V/ab P(z), (4) where P(z) is a Gaussian distribution term of the form P(z) = 1/o√2π e-z2/2γ2 (5) with a time dependent standard deviation o = √2 VDt. (6) Hence, a pulse of thermal neutrons introduced at the origin spreads Out with time in a symmetrical manner about the z = 0 plane. However, the variation of amplitude with time at any position along the z axis shows that a peak value of neutron density does move out from the origin with a decreasing amplitude. Although the multiplication and transverse leakage influence the characteristics of the disturbance, it does propagate away from the source in a manner similar to the propagation of neutron waves. The propagation of a thermal-neutron pulse has been demonstrated experimentally in 1962 at the University of Florida using a pulsed-neutron source and a ''Thermalizer box''. However, the method used for the experiments reported here was the cross correlation between the pseudo-random binary (off-on) variation of source strength and the resulting variation of neutron density in the exponential assembly. Data are given for experiments carried out on both light- and heavy-water moderated assemblies using natural uranium. The results are discussed in terms of the theoretical relations derived and the physical phenomena taking place. The validity of the derived relationships and the need for considering higher harmonics for various arrangements of fuel and moderator are discussed briefly. (author)

  15. Transthoracic Cardiac Acoustic Radiation Force Impulse Imaging

    Science.gov (United States)

    Bradway, David Pierson

    This dissertation investigates the feasibility of a real-time transthoracic Acoustic Radiation Force Impulse (ARFI) imaging system to measure myocardial function non-invasively in clinical setting. Heart failure is an important cardiovascular disease and contributes to the leading cause of death for developed countries. Patients exhibiting heart failure with a low left ventricular ejection fraction (LVEF) can often be identified by clinicians, but patients with preserved LVEF might be undetected if they do not exhibit other signs and symptoms of heart failure. These cases motivate development of transthoracic ARFI imaging to aid the early diagnosis of the structural and functional heart abnormalities leading to heart failure. M-Mode ARFI imaging utilizes ultrasonic radiation force to displace tissue several micrometers in the direction of wave propagation. Conventional ultrasound tracks the response of the tissue to the force. This measurement is repeated rapidly at a location through the cardiac cycle, measuring timing and relative changes in myocardial stiffness. ARFI imaging was previously shown capable of measuring myocardial properties and function via invasive open-chest and intracardiac approaches. The prototype imaging system described in this dissertation is capable of rapid acquisition, processing, and display of ARFI images and shear wave elasticity imaging (SWEI) movies. Also presented is a rigorous safety analysis, including finite element method (FEM) simulations of tissue heating, hydrophone intensity and mechanical index (MI) measurements, and thermocouple transducer face heating measurements. For the pulse sequences used in later animal and clinical studies, results from the safety analysis indicates that transthoracic ARFI imaging can be safely applied at rates and levels realizable on the prototype ARFI imaging system. Preliminary data are presented from in vivo trials studying changes in myocardial stiffness occurring under normal and abnormal heart function. Presented is the first use of transthoracic ARFI imaging in a serial study of heart failure in a porcine model. Results demonstrate the ability of transthoracic ARFI to image cyclically-varying stiffness changes in healthy and infarcted myocardium under good B-mode imaging conditions at depths in the range of 3-5 cm. Challenging imaging scenarios such as deep regions of interest, vigorous lateral motion and stable, reverberant clutter are analyzed and discussed. Results are then presented from the first study of clinical feasibility of transthoracic cardiac ARFI imaging. At the Duke University Medical Center, healthy volunteers and patients having magnetic resonance imaging-confirmed apical infarcts were enrolled for the study. The number of patients who met the inclusion criteria in this preliminary clinical trial was low, but results showed that the limitations seen in animal studies were not overcome by allowing transmit power levels to exceed the FDA mechanical index (MI) limit. The results suggested the primary source of image degradation was clutter rather than lack of radiation force. Additionally, the transthoracic method applied in its present form was not shown capable of tracking propagating ARFI-induced shear waves in the myocardium. Under current instrumentation and processing methods, results of these studies support feasibility for transthoracic ARFI in high-quality B-Mode imaging conditions. Transthoracic ARFI was not shown sensitive to infarct or to tracking heart failure in the presence of clutter and signal decorrelation. This work does provide evidence that transthoracic ARFI imaging is a safe non-invasive tool, but clinical efficacy as a diagnostic tool will need to be addressed by further development to overcome current challenges and increase robustness to sources of image degradation.

  16. Impulsivity in Decision-Making: An Event-Related Potential Investigation

    OpenAIRE

    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 ma...

  17. Impulsivity trait in the early symptomatic BACHD transgenic rat model of Huntington disease.

    Science.gov (United States)

    Manfr, Giuseppe; Doyre, Valrie; 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. PMID:26592164

  18. Impulsive stabilization of a class of nonlinear system with bounded gain error

    International Nuclear Information System (INIS)

    Considering mechanical limitation or device restriction in practical application, this paper investigates impulsive stabilization of nonlinear systems with impulsive gain error. Compared with the existing impulsive analytical approaches, the proposed impulsive control method is more practically applicable, which includes control gain error with an acceptable boundary. A sufficient criterion for global exponential stability of an impulsive control system is derived, which relaxes the condition for precise impulsive gain efficiently. The effectiveness of the proposed method is confirmed by theoretical analysis and numerical simulation based on Chua's circuit. (general)

  19. Impulse Electrotherapy in Reduction Treatment of the Tuboperitoneal Sterility

    Directory of Open Access Journals (Sweden)

    Belousova T.E.

    2010-03-01

    Full Text Available Aim of investigation is assessment of the impulse electrotherapy clinical effectiveness in a complex treatment of patients with the tuboperitoneal sterility. Materials and Methods. A complex clinicolaboratory examination of 114 patients with the tuboperitoneal sterility (TPS is made. All the females were divided into 3 groups. The females underwent a laparoscopic operation and ultrasonic therapy in the impulse mode to a suprapubic zone in the early postoperative period (1015 procedures in the 1st control group (n=30. The females underwent a laparoscopic operation and a course of impulse electrotherapy with the ?SCANAR-1-HT? apparatus with a use of vaginal electrode (1015 procedures in the 2nd group (n=42. A course of impulse electrotherapy was conducted without a vaginal electrode use (1015 procedures in the 3d group (n=42. Two parameters were considered at assessment of the female reproductive function reduction: a conservation of the uterine tube permeability after laparoscopy and a spontaneous pregnancy beginning. A hysterosalpingography was made in all the patients in 23 months after a reduction treatment. Results. An impulse electrotherapy used in the early reduction period after a laparoscopic operation in patients with the tuboperitoneal sterility improves the uterine tube permeability conservation values by 28%, the fertility values by 20% compared to a group, where an ultrasonic therapy in the impulse mode was used in the early reduction period. The proposed method normally effects the lipid peroxidation and antioxidant system state, a homeostasis, leads to a hemodynamics normalization in the small pelvis organs, a decrease of the organism regulatory mechanism tension degree, a decrease of a sympathetic nervous system influence and increase of a parasympathetic nervous system tonus, has an expressed psychocorrugating effect.

  20. Food reinforcement and impulsivity in overweight children and their parents.

    Science.gov (United States)

    Epstein, Leonard H; Dearing, Kelly K; Temple, Jennifer L; Cavanaugh, Meghan D

    2008-08-01

    Pediatric obesity involves choices among healthy and less healthy alternatives, as well as choices whose consequences vary over time, such as engaging in unhealthy behaviors now at the expense of future health. The purpose of this study was to examine the relative reinforcing value of food and behavioral impulsivity under different experimental conditions in a sample of 50 families screened for participation in a pediatric obesity treatment program. Relative reinforcing value for food versus money was studied under conditions in which increased response requirements were placed on either access to food or money, and the amount of money, the alternative reinforcer, was varied. Impulsivity for small immediate versus larger delayed monetary rewards was studied under conditions in which the value of the immediate reward and the duration of the delay were varied. Results showed that response requirements affected the choice of food for both parents and children (p<0.001), and there was a significant correlation between the number of food reinforcers chosen by parents and children (r=0.57, p<0.001). The value of the immediate reward differentially influenced choice of the immediate reward for parents and children (p<0.05), with children (p<0.001) but not parents (p=0.36) more impulsive as value of the immediate reward increased. The length of the delay influenced both parent (p=0.004) and child (p<0.01) choice of the immediate reward. Parent and child impulsivity were not correlated (r=0.15, p=0.29). This study suggests that food reinforcement may be more similar between parents and children than behavioral impulsivity, though additional research using other measures of relative reinforcing value and impulsivity is warranted. PMID:18549991

  1. Fast Impulse Noise Removal from Highly Corrupted Images

    CERN Document Server

    Hosseini, Hossein

    2011-01-01

    In this paper, we suggest a general model for the fixed-valued impulse noise and propose a two-stage method for high density noise suppression while preserving the image details. In the first stage, we apply an iterative impulse detector, exploiting the image entropy, to identify the corrupted pixels and then employ an Adaptive Iterative Mean filter (AIM) to restore them. The filter is adaptive in terms of the number of iterations, which is different for each noisy pixel, according to their Euclidean distance from the nearest uncorrupted pixel. Experimental results show that the AIM filter is fast and outperforms the best existing techniques in both objective and subjective performance measures.

  2. Investigation of the impulse response of an image inversion interferometer

    Science.gov (United States)

    Weigel, D.; Babovsky, H.; Kiessling, A.; Kowarschik, R.

    2010-02-01

    Based on the proposal of Wicker and Heintzmann "Interferometric resolution improvement for confocal microscopes" [1] we demonstrate in principle the functionality of an image inversion interferometer (III) experimentally, which can be described by an appropriate frequency transfer function. Thereby, the FWHM of the impulse response narrows around 30% compared to the PSF of a classical system. The experimental data yield a FWHM of the impulse response of 0.83 μm as compared to the theoretical value of 1.21 μm at λ0=589 nm by a wide field detection (NA=0.25) without an interferometer.

  3. Double-impulse magnetic focusing of launched cold atoms

    CERN Document Server

    Arnold, A S; Pritchard, M J; Smith, D A; Arnold, Aidan S; Hughes, Ifan G; Pritchard, Matthew J; Smith, David A

    2006-01-01

    We have theoretically investigated 3D focusing of a launched cloud of cold atoms using a pair of magnetic lens pulses (the alternate-gradient method). Individual lenses focus radially and defocus axially or vice-versa. We discuss the performance of the two possible pulse sequences and find they are ideal for loading both `pancake' and `sausage' shaped magnetic/optical microtraps. We show that focusing aberrations are considerably smaller for double-impulse magnetic lenses compared to single-impulse magnetic lenses.

  4. Reduced rank adaptive filtering in impulsive noise environments

    KAUST Repository

    Soury, Hamza

    2014-11-01

    An impulsive noise environment is considered in this paper. A new aspect of signal truncation is deployed to reduce the harmful effect of the impulsive noise to the signal. A full rank direct solution is derived followed by an iterative solution. The reduced rank adaptive filter is presented in this environment by using two methods for rank reduction, while the minimized objective function is defined using the Lp norm. The results are presented and the efficiency of each method is discussed. © 2014 IEEE.

  5. Impulsive and hybrid dynamical systems stability, dissipativity, and control

    CERN Document Server

    Haddad, Wassim M; Nersesov, Sergey G

    2014-01-01

    This book develops a general analysis and synthesis framework for impulsive and hybrid dynamical systems. Such a framework is imperative for modern complex engineering systems that involve interacting continuous-time and discrete-time dynamics with multiple modes of operation that place stringent demands on controller design and require implementation of increasing complexity--whether advanced high-performance tactical fighter aircraft and space vehicles, variable-cycle gas turbine engines, or air and ground transportation systems. Impulsive and Hybrid Dynamical Systems goes beyond similar

  6. Single-impulse magnetic focusing of launched cold atoms

    CERN Document Server

    Pritchard, M J; Smith, D A; Hughes, I G; Pritchard, Matthew J; Arnold, Aidan S; Smith, David A; Hughes, Ifan G

    2004-01-01

    We have theoretically investigated the focusing of a launched cloud of cold atoms. Time-dependent spatially-varying magnetic fields are used to impart impulses leading to a three-dimensional focus of the launched cloud. We discuss possible coil arrangements for a new focusing regime: isotropic 3D focusing of atoms with a single-impulse magnetic lens. We investigate focusing aberrations and find that, for typical experimental parameters, the widely used assumption of a purely harmonic lens is often inaccurate. The baseball lens offers the best possibility for isotropically focusing a cloud of weak-field-seeking atoms in 3D.

  7. Addictions and Personality Traits: Impulsivity and Related Constructs.

    Science.gov (United States)

    Mitchell, Marci R; Potenza, Marc N

    2014-03-01

    Behavioral tendencies that might be captured through self-report measures may provide insight into personality features that are associated with substance addictions. Recently, impulsivity and related constructs, such as sensation-seeking, have been examined to help better understand their relationships with addictions. Here, we review recent findings that show links over developmental epochs between addictive behaviors and impulsivity, sensation-seeking, and other constructs that are theoretically linked. These findings have significant implications for generating improved treatments and interventions aimed at preventing the development of addictive disorders. PMID:24772382

  8. A Serious Videogame as an Additional Therapy Tool for Training Emotional Regulation and Impulsivity Control in Severe Gambling Disorder

    OpenAIRE

    Tárrega, Salomé; Castro-Carreras, Laia; Fernández-Aranda, Fernando; Granero, Roser; Giner-Bartolomé, Cristina; Aymamí, Neus; Gómez-Peña, Mónica; Juan J Santamaría; Forcano, Laura; Steward, Trevor; Menchón, José M.; Jiménez-Murcia, Susana

    2015-01-01

    Background: Gambling disorder (GD) is characterized by a significant lack of self-control and is associated with impulsivity-related personality traits. It is also linked to deficits in emotional regulation and frequently co-occurs with anxiety and depression symptoms. There is also evidence that emotional dysregulation may play a mediatory role between GD and psychopathological symptomatology. Few studies have reported the outcomes of psychological interventions that specifically address the...

  9. Sufficient Conditions for the Lp-Equivalence Between two Nonlinear Impulse Differential Equations

    OpenAIRE

    Georgieva, A

    2008-01-01

    Sufficient conditions for the Lp-equivalence between two nonlinear impulse differential equations with unbounded linear parts and possibly unbounded nonlinearity parts are given. An example of two nonlinear impulse differential parabolic equations is considered.

  10. The restraint bias: how the illusion of self-restraint promotes impulsive behavior.

    Science.gov (United States)

    Nordgren, Loran F; van Harreveld, Frenk; van der Pligt, Joop

    2009-12-01

    Four studies examined how impulse-control beliefs--beliefs regarding one's ability to regulate visceral impulses, such as hunger, drug craving, and sexual arousal-influence the self-control process. The findings provide evidence for a restraint bias: a tendency for people to overestimate their capacity for impulse control. This biased perception of restraint had important consequences for people's self-control strategies. Inflated impulse-control beliefs led people to overexpose themselves to temptation, thereby promoting impulsive behavior. In Study 4, for example, the impulse-control beliefs of recovering smokers predicted their exposure to situations in which they would be tempted to smoke. Recovering smokers with more inflated impulse-control beliefs exposed themselves to more temptation, which led to higher rates of relapse 4 months later. The restraint bias offers unique insight into how erroneous beliefs about self-restraint promote impulsive behavior. PMID:19883487

  11. What is Impulse Buying? An analytical network processing framework for prioritizing factors affecting impulse buying

    Directory of Open Access Journals (Sweden)

    Javad Siahkali Moradi

    2012-08-01

    Full Text Available One of the most important issues affecting profitability is to determine the impact of different factors influencing purchasing activities. In this paper, we perform an extensive literature survey to detect different purchasing factors influencing customers' behavior. The factors are categorized in three different groups and they are ranked using analytical network process. The results of our survey indicate that three factors of personal, product and situational play important roles in purchasing impulse. The personal item includes different factors where demographic characteristic factors receive the highest ranking (35% followed by other factors are feelings, excitement and fun, self identify, education and novelty. There are also three sub-factors associated with demographic characteristics including gender, age and race and the weights are 0.46748, 0.42668 and 0.10584, respectively, which means gender is the most important factor followed by age and race. Finally, the other factor is associated with situational factors' group, which includes presence of others, culture, design of store, time available, local market condition, sales staff and self service with the relative importance of 0.04296, 0.08733, 0.12130, 0.22217, 0.05643, 0.15346 and 0.31635, respectively.

  12. Impulsivity, gender, and the platelet serotonin transporter in healthy subjects

    OpenAIRE

    Donatella Marazziti; Stefano Baroni; Irene Masala; et al

    2009-01-01

    Donatella Marazziti, Stefano Baroni, Irene Masala, Francesca Golia, Giorgio Consoli, Gabriele Massimetti, Michela Picchetti, Mario Catena Dell’Osso, Gino Giannaccini, Laura Betti, Antonio Lucacchini, Antonio CiapparelliDipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, University of Pisa, Pisa, ItalyAbstract: The present study explored the possible relationships between impulsivity, gender, and a peripheral serotonergic marker, the platelet serotonin (5-HT) tr...

  13. The Impact of Television on Preschoolers' Perseverance, Impulsivity and Restlessness.

    Science.gov (United States)

    Collins, Patricia A.

    This study tested the claim that television viewing reduces preschoolers' perseverance, increases their impulsivity, and induces restlessness. In the first of two laboratory visits with a parent, 328 5-year-olds were given the Peabody Picture Vocabulary Test. During the second visit, the parent completed the Parent Temperament Questionnaire and…

  14. Periodic components of hand acceleration/deceleration impulses during telemanipulation

    International Nuclear Information System (INIS)

    Responsiveness is the ability of a telemanipulator to recreate user trajectories and impedance in time and space. For trajectory production, a key determinant of responsiveness is the ability of the system to accept user inputs, which are forces on the master handle generated by user hand acceleration/deceleration (a/d) impulses, and translate them into slave arm acceleration/deceleration. This paper presents observations of master controller a/d impulses during completion of a simple target acquisition task. Power spectral density functions (PSDF's) calculated from hand controller a/d impulses were used to assess impulse waveform. The relative contributions of frequency intervals ranging up to 25 Hz for three spatially different versions of the task were used to determine which frequencies were most important. The highest relative power was observed in frequencies between 1 Hz and 6 Hz. The key frequencies related to task difficulty were in the range from 2 Hz to 8 Hz. the results provide clues to the source of the performance inhibition

  15. Solar Flare Impulsive Phase Emission Observed with SDO/EVE

    CERN Document Server

    Kennedy, Michael B; Mathioudakis, Mihalis; Keenan, Francis P

    2013-01-01

    Differential emission measures (DEMs) during the impulsive phase of solar flares were constructed using observations from the EUV Variability Experiment (EVE) and the Markov-Chain Monte Carlo method. Emission lines from ions formed over the temperature range log T = 5.8 - 7.2 allow the evolution of the DEM to be studied over a wide temperature range at 10s cadence. The technique was applied to several M- and X-class flares, where impulsive phase EUV emission is observable in the disk-integrated EVE spectra from emission lines formed up to 3 - 4 MK, and we use spatially-unresolved EVE observations to infer the thermal structure of the emitting region. For the nine events studied the DEMs exhibited a two component distribution during the impulsive phase, a low temperature component with peak temperature of 1 - 2 MK, and a broad high temperature one from 7 - 30 MK. A bimodal high temperature component is also found for several events, with peaks at 8 and 25 MK during the impulsive phase. The origin of the emissi...

  16. Minimum impulse trajectories for Mars round trip missions

    Science.gov (United States)

    Horvat, Glen M.; Alexander, Stephen W.

    1992-01-01

    Data are presented for minimum-impulse earth-Mars round-trip trajectories for the 2010 to 2027 Mars launch opportunities. Round-trip mission times from 120 to 600 days, including a 30-day rendezvous at Mars, for direct trajectories and trajectories utilizing a Venus gravitational assist are considered. Optimal planetary launch and arrival dates and total impulse requirements are based on all maneuvers being performed propulsively with no finite burn or other losses. Direct trajectories have the lowest impulse requirements for shorter mission times and Venus gravitational assist trajectories have the lowest impulse requirements for longer mission times. It is shown that one can depart on trajectories to Mars, beginning with lower energy trajectories to the moon. The fuel savings varies, depending on the final energy level required and on the swingby procedure used. Procedures discussed include single lunar swingbys, double-powered or unpowered lunar swingbys, third lunar flybys a year later, and gravity assists by Venus and earth after the final lunar swingby.

  17. Strict Stability Criteria for Impulsive Functional Differential Systems

    Directory of Open Access Journals (Sweden)

    Kaien Liu

    2008-02-01

    Full Text Available By using Lyapunov functions and Razumikhin techniques, the strict stability of impulsive functional differential systems is investigated. Some comparison theorems are given by virtue of differential inequalities. The corresponding theorems in the literature can be deduced from our results.

  18. Developmental role of acetylcholinesterase in impulse control in zebrafish.

    Science.gov (United States)

    Parker, Matthew O; Brock, Alistair J; Sudwarts, Ari; Teh, Muy-Teck; Combe, Fraser J; Brennan, Caroline H

    2015-01-01

    Cellular and molecular processes that mediate individual variability in impulsivity, a key behavioral component of many neuropsychiatric disorders, are poorly understood. Zebrafish heterozygous for a nonsense mutation in ache (ache (sb55/+)) showed lower levels of impulsivity in a 5-choice serial reaction time task (5-CSRTT) than wild type and ache(+∕+). Assessment of expression of cholinergic (nAChR), serotonergic (5-HT), and dopamine (DR) receptor mRNA in both adult and larval (9 dpf) ache (sb55/+) revealed significant downregulation of chrna2, chrna5, and drd2 mRNA in ache (sb55/+) larvae, but no differences in adults. Acute exposure to cholinergic agonist/antagonists had no effect on impulsivity, supporting the hypothesis that behavioral effects observed in adults were due to lasting impact of developmental alterations in cholinergic and dopaminergic signaling. This shows the cross-species role of cholinergic signaling during brain development in impulsivity, and suggests zebrafish may be a useful model for the role of cholinergic pathways as a target for therapeutic advances in addiction medicine. PMID:26528153

  19. Developmental role of acetylcholinesterase in impulse control in zebrafish

    Directory of Open Access Journals (Sweden)

    Matthew O Parker

    2015-10-01

    Full Text Available Cellular and molecular processes that mediate individual variability in impulsivity, a key behavioural component of many neuropsychiatric disorders, are poorly understood. Zebrafish heterozygous for a nonsense mutation in Ache (achesb55/+ showed lower levels of impulsivity in a 5-choice serial reaction time task (5-CSRTT than wild type and ache+/+. Assessment of expression of cholinergic (nAChR, serotonergic (5-HT and dopamine (DR receptor mRNA in both adult and larval (9dpf achesb55/+ revealed significant downregulation of Chrna2, Chrna5 and Drd2 mRNA in achesb55/+ larvae, but no differences in adults. Acute exposure to cholinergic agonist/antagonists had no effect on impulsivity, supporting the hypothesis that behavioural effects observed in adults were due to lasting impact of developmental alterations in cholinergic and dopaminergic signalling. This shows the cross-species role of cholinergic signalling during brain development in impulsivity, and suggests zebrafish may be a useful model for the role of cholinergic pathways as a target for therapeutic advances in addiction medicine.

  20. High energy nucleon incident optical potential by relativistic impulse approximation

    International Nuclear Information System (INIS)

    The optical potentials by relativistic impulse approximation (RIA) are utilized for the high energy nucleon incidence. The nucleon-nucleon scattering amplitudes are derived from the phase shift and parametrized as a function of the incident nucleon energy. The optical potential by RIA reproduces the experimental data. (author)

  1. Cone-valued impulsive differential and integrodifferential inequalities

    OpenAIRE

    Sam Olatunji Ale; Benjamin Oyediran Oyelami; Maligie S. Sesay

    2005-01-01

    In this paper, we present impulsive analogues of the Gronwall-Bellman inequalities. Conditions for the existence of maximal solutions of some integrodifferential equations are obtained by finding upper bounds for these inequalities. Using monotone iterative techniques and a fixed point theorem, we obtained a priori estimates for the inequalities.

  2. Cone-valued impulsive differential and integrodifferential inequalities

    Directory of Open Access Journals (Sweden)

    Sam Olatunji Ale

    2005-06-01

    Full Text Available In this paper, we present impulsive analogues of the Gronwall-Bellman inequalities. Conditions for the existence of maximal solutions of some integrodifferential equations are obtained by finding upper bounds for these inequalities. Using monotone iterative techniques and a fixed point theorem, we obtained a priori estimates for the inequalities.

  3. Useful In-space Impulse Generation Powered by Laser Energy

    International Nuclear Information System (INIS)

    After a pulsed laser beam irradiation, the pressure behind a projectile is increased due to shock wave generated by the ablating gas, resulting in a propulsive impulse generation. This principle can be applied to orbiting space debris. As the first stage, a CO2 laser beam was shot on various ablated material in the atmosphere, and projectile launch performance was measured

  4. Existence of solutions to singular fractional differential systems with impulses

    Directory of Open Access Journals (Sweden)

    Xingyuan Liu

    2012-11-01

    Full Text Available By constructing a weighted Banach space and a completely continuous operator, we establish the existence of solutions for singular fractional differential systems with impulses. Our results are proved using the Leray-Schauder nonlinear alternative, and are illustrated with examples.

  5. Impulse response measurements with an off-line cross correlator

    International Nuclear Information System (INIS)

    The impulse responses of simulated systems have been computed by off-line cross-correlation of the system input and output signals. The input test signal consisted of a discrete interval binary code whose autocorrelation was a triangular pulse at zero lag. The main object of the experiments was to study the inaccuracies introduced in ideal, noise free systems by determining the impulse response digitally from sampled versions of the system input and output signals. A second object was to determine the error introduced by adding controlled amounts of uncorrelated noise at the system outputs. The experimental results showed that for signal to noise ratios greater than 10:1 in the mean square sense, the impulse responses may be determined with reasonable accuracy using only one cycle of the binary code. The method lends itself to on-line computation of system impulse responses. The latter could be used to monitor the stability of the system or to determine control parameters in an adaptive control system. (author)

  6. Model Predictive Control based on Finite Impulse Response Models

    DEFF Research Database (Denmark)

    Prasath, Guru; Jørgensen, John Bagterp

    2008-01-01

    We develop a regularized l2 finite impulse response (FIR) predictive controller with input and input-rate constraints. Feedback is based on a simple constant output disturbance filter. The performance of the predictive controller in the face of plant-model mismatch is investigated by simulations...

  7. New examples of sandwich gravitational waves and their impulsive limit

    OpenAIRE

    Podolsky, J.; Vesely, K.

    1998-01-01

    Non-standard sandwich gravitational waves are constructed from the homogeneous pp vacuum solution and the motions of free test particles in the space-times are calculated explicitly. They demonstrate the caustic property of sandwich waves. By performing limits to impulsive gravitational wave it is demonstrated that the resulting particle motions are identical regardless of the ''initial'' sandwich.

  8. Construction and enlargement of dilatonic wormholes by impulsive radiation

    OpenAIRE

    Koyama, Hiroko; Hayward, Sean A.; Kim, Sung-Won

    2002-01-01

    The dynamical behavior of traversable wormholes and black holes under impulsive radiation is studied in an exactly soluble dilaton gravity model. Simple solutions are presented where a traversable wormhole is constructed from a black hole, or the throat of a wormhole is stably enlarged or reduced. These solutions illustrate the basic operating principles needed to construct similar analytic solutions in full Einstein gravity.

  9. Experimental Characterization of Extremely Broadband THz Impulse Radio Communication Systems

    DEFF Research Database (Denmark)

    Yu, Xianbin; Vidal, Borja; Galili, Michael; Jepsen, Peter Uhd; Oxenløwe, Leif Katsuo

    2015-01-01

    using a photoconductive antenna (PCA). We analyze the performance in terms of bandwidth and the features of the THz pulses. A 15 dB bandwidth of 1 THz confirms that this THz impulse system has a great potential of supporting ultrafast data rates, eventually for Terabit wireless communication era....

  10. Recreational Drug Use and Impulsivity in a Population of Canadian Undergraduate Drinkers

    OpenAIRE

    Balodis, Iris M.; Potenza, Marc N.; Olmstead, Mary C

    2010-01-01

    The consumption of drugs during young adulthood may be particularly detrimental given important neurodevelopmental changes occurring during this period. As impulsivity may lead to substance use and substance use to the commission of seemingly impulsive acts, an improved understanding of the relationship between alcohol use, other substance use and impulsivity in young adults is important. We gathered information on self-reported impulsivity, recreational drug use, and drinking habits of 205 (...

  11. Recreational drug use and impulsivity in a population of Canadian undergraduate drinkers

    OpenAIRE

    IrisMBalodis; MarcNPotenza

    2010-01-01

    The consumption of drugs during young adulthood may be particularly detrimental given important neurodevelopmental changes occurring during this period. As impulsivity may lead to substance use and substance use to the commission of seemingly impulsive acts, an improved understanding of the relationship between alcohol use, other substance use and impulsivity in young adults is important. We gathered information on self-reported impulsivity, recreational drug use, and drinking habits of 205 (...

  12. The influence of culture on students' impulsive buying behaviour in the Vaal Triangle area / Luzaan Hamilton

    OpenAIRE

    Hamilton, Luzaan

    2011-01-01

    Impulse buying or unplanned purchases by consumers constitute a major proportion of purchases in certain product categories. Studies in the United States widely reported that impulse consumer buying behaviour accounts for up to 80% of all purchases in certain product categories, and it has been suggested that purchases of new products result more from impulse purchasing than from prior planning. South Africa is a nation of shoppers with increasing numbers defined as impulse buyers who respond...

  13. Stability Analysis for Impulsive Stochastic Reaction-Diffusion Differential System and Its Application to Neural Networks

    OpenAIRE

    Du, Yanke; Li, Yanlu; Xu, Rui

    2013-01-01

    This paper is concerned with the stability of impulsive stochastic reaction-diffusion differential systems with mixed time delays. First, an equivalent relation between the solution of a stochastic reaction-diffusion differential system with time delays and impulsive effects and that of corresponding system without impulses is established. Then, some stability criteria for the stochastic reaction-diffusion differential system with time delays and impulsive effects are derived. Finally, the st...

  14. Understanding the construct of impulsivity and its relationship to alcohol use disorders

    OpenAIRE

    Dick, Danielle M; Smith, Gregory; Olausson, Peter; Mitchell, Suzanne H.; Leeman, Robert F.; O'Malley, Stephanie S.; Sher, Kenneth

    2010-01-01

    There are well-established links between impulsivity and alcohol use in humans and other model organisms; however, the etiological nature of these associations remains unclear. This is likely due, in part, to the heterogeneous nature of the construct of impulsivity. Many different measures of impulsivity have been employed in human studies, using both questionnaire and laboratory-based tasks. Animal studies also use multiple tasks to assess the construct of impulsivity. In both human and anim...

  15. Multidimensional Measures of Impulsivity in Obsessive-Compulsive Disorder: Cannot Wait and Stop

    OpenAIRE

    Sohn, Sung Yun; Kang, Jee In; Namkoong, Kee; Kim, Se Joo

    2014-01-01

    Objective Although the relationship between obsessive compulsive disorder (OCD) and impulsivity has long been debated, impulsivity has not been systematically examined in clinical samples of OCD. Meanwhile, recent findings suggest that impulsivity is multi-dimensional construct that can be examined through several constructs. Therefore, this study is aimed to evaluate multiple facets of impulsivity in OCD. Method The recruitment includes 80 OCD and 76 healthy control participants. Participant...

  16. Heroin and amphetamine users display opposite relationships between trait and neurobehavioral dimensions of impulsivity

    OpenAIRE

    Vassileva, Jasmin; Paxton, Jessica; Moeller, F. Gerard; Wilson, Michael; Bozgunov, Kiril; Martin, Eileen; Gonzalez, Raul; Vasilev, Georgi

    2013-01-01

    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 a...

  17. A model-based analysis of impulsivity using a slot-machine gambling paradigm

    OpenAIRE

    Paliwal, Saee; Petzschner, Frederike H; Schmitz, Anna Katharina; Tittgemeyer, Marc; Stephan, Klaas E.

    2014-01-01

    Impulsivity plays a key role in decision-making under uncertainty. It is a significant contributor to problem and pathological gambling (PG). Standard assessments of impulsivity by questionnaires, however, have various limitations, partly because impulsivity is a broad, multi-faceted concept. What remains unclear is which of these facets contribute to shaping gambling behavior. In the present study, we investigated impulsivity as expressed in a gambling setting by applying computational model...

  18. A Model-based Analysis of Impulsivity Using a Slot-Machine Gambling Paradigm

    OpenAIRE

    Saee Paliwal; Anna Katharina Schmitz; Klaas Enno Stephan

    2014-01-01

    Impulsivity plays a key role in decision-making under uncertainty. It is a significant contributor to problem and pathological gambling. Standard assessments of impulsivity by questionnaires, however, have various limitations, partly because impulsivity is a broad, multi-faceted concept. What remains unclear is which of these facets contribute to shaping gambling behavior. In the present study, we investigated impulsivity as expressed in a gambling setting by applying computational modeling t...

  19. Lag Synchronization of a Class of Time-delayed Chaotic Neural Networks by Impulsive Control

    Directory of Open Access Journals (Sweden)

    Jing Wan

    2013-06-01

    Full Text Available The paper studies the exponential lag synchronization of a class of delayed chaotic neural networks with impulsive effects via the unidirectional linear coupling. Some sufficient conditions are derived by establishing impulsive differential delay inequality and using M-matrix theory. An illustrative example is also provided to show the effectiveness and feasibility of the impulsive control method.  

  20. Impulsivity is relevant for trauma exposure and PTSD symptoms in a non-clinical population.

    Science.gov (United States)

    Netto, Liana R; Pereira, Juliana L; Nogueira, José F; Cavalcanti-Ribeiro, Patrícia; Santana, Rejane Conceição; Teles, Carlos A; Koenen, Karestan C; Quarantini, Lucas C

    2016-05-30

    Impulsivity is a relevant construct for explaining both normal individual differences in personality and more extreme personality disorder, and is often investigated within clinical populations. This study aims to explore the college students' impulsivity patterns and to investigate the association across levels of impulsivity with trauma exposure and PTSD development in a non-clinical population. A one-phase census survey of seven college institutions assessed 2213 students in three metropolitan regions of Northeastern Brazil. All subjects anonymously completed a self-applied protocol consisting of: a socio-demographic questionnaire, Trauma History Questionnaire (THQ), PTSD Checklist (PCL-C), and Barratt Impulsiveness Scale (BIS-11). The median for frequency of trauma exposure was 4 events for people with low and normal impulsivity, and 6 for highly impulsive ones. Individuals with higher impulsivity presented earlier exposition than non-impulsive ones, and worst outcome: 12.4% with PTSD, against 8.4% and 2.3% (normal and low impulsivity). Of the three factors of impulsivity, the Attentional factor conferred the strongest association with PTSD development. Results suggest that impulsivity is also a relevant trait in a non-clinical population and is associated with trauma exposure and PTSD. Strategies to promote mental health in adolescents may be pertinent, especially with the aim of managing impulsivity. PMID:27016879

  1. The Neurobiology and Genetics of Impulse Control Disorders: Relationships to Drug Addictions

    OpenAIRE

    Brewer, Judson A.; Potenza, Marc N.

    2007-01-01

    Impulse control disorders (ICDs), including pathological gambling, trichotillomania, kleptomania and others, have been conceptualized to lie along an impulsive-compulsive spectrum. Recent data have suggested that these disorders may be considered addictions. Here we review the genetic and neuropathological bases of the impulse control disorders and consider the disorders within these non-mutually exclusive frameworks.

  2. Carrion crows cannot overcome impulsive choice in a quantitative exchange task.

    Science.gov (United States)

    Wascher, Claudia A F; Dufour, Valerie; Bugnyar, Thomas

    2012-01-01

    The ability to control an immediate impulse in return for a more desirable - though delayed - outcome has long been thought to be a uniquely human feature. However, studies on non-human primates revealed that some species are capable of enduring delays in order to get food of higher quality or quantity. Recently two corvid species, common raven (Corvus corax) and carrion crow (Corvus corone corone), exchanged food for a higher quality reward though seemed less capable of enduring delays when exchanging for the same food type in a higher quantity. In the present study, we specifically investigated the ability of carrion crows to overcome an impulsive choice in a quantitative exchange task. After a short delay, individuals were asked to give back an initial reward (cheese) to the human experimenter in order to receive a higher amount of the same reward (two, four, or eight pieces). We tested six captive crows - three individuals never exchanged the initial reward for a higher quantity; the other three birds did exchange though at very low rates. We performed a preference test between one or more pieces of cheese in order to address whether crow poor performance could be due to an inability to discriminate between different quantities or not attributing a higher value to the higher quantities. All birds chose the higher quantities significantly more often, indicating that they can discriminate between quantities and that higher quantities are more desirable. Taken together, these results suggest that, although crows may possess the cognitive abilities to judge quantities and to overcome an impulsive choice, they do so only in order to optimize the qualitative but not quantitative output in the exchange paradigm. PMID:22529833

  3. Carrion crows cannot overcome impulsive choice in a quantitative exchange task

    Directory of Open Access Journals (Sweden)

    ThomasBugnyar

    2012-04-01

    Full Text Available The ability to control an immediate impulse for a future, more preferred outcome has long been thought to be a uniquely human feature. However, studies on non-human primates revealed that some monkeys and apes are capable of enduring delays to get a more preferred food and/or more food of the same kind. Recently two corvid species, the common raven (Corvus corax and carrion crow (Corvus corone corone, exchanged food for a better quality reward, whereas they seemed to have difficulties to do so for a higher quantity. In the present study we specifically investigated carrion crows’ ability to overcome an impulsive choice in a quantitative exchange task. After a short delay, individuals were asked to give back an initial reward (cheese to the human experimenter in order to receive a higher amount of the same reward (2, 4 or 8 pieces. We successfully tested six captive crows. Three individuals never exchanged one piece of cheese against a higher quantity; the other three birds did exchange at very low rates. In order to rule out, that crows’ poor performance is due to the fact that they cannot discriminate between different quantities or that they do not attribute a higher value to higher quantities, we performed a preference test between one and more pieces of cheese. All birds chose the higher quantities significantly more often, indicating that they can discriminate between quantities and that higher quantities actually have a value for them. Taken together, these results suggest that, although crows may possess the cognitive abilities to judge quantities and to overcome an impulsive choice, they do so only in order to optimize the qualitative but not quantitative output in the exchange paradigm.

  4. Impulsive Driving: Definition and Measurement Using the I-Driving Scale (IDS).

    Science.gov (United States)

    Pérez-Moreno, Elisa; Hernández-Lloreda, María José; Gallego-Largo, Trinidad Ruiz; Castellanos, Miguel Ángel

    2015-01-01

    Impulsivity has been widely studied in the context of traffic. The trait is believed to be the root of some accidents, along with other variables like aggression and anger. The present research objective is to develop a new scale - the I-Driving Scale (IDS) - to evaluate and measure the construct of impulsivity in specific driving situations. To that end, two studies were conducted, with 162 and 107 participants, respectively. In both studies, participants were recruited via their social networks, and answered anonymously. In addition to the IDS, they completed the Use the Vehicle to Express Anger subscale of the Driving Anger Expression Inventory (DAX), the Driving Anger Scale (DAS), and the Barratt Impulsivity Scale (BIS11), and also provided demographic information. The final scale had 11 items falling into two factors: impatience, and aggressiveness/abruptness. The results show a high consistency (αT = .81, αI = .70, and αA = .85 in the first study; αT = .83, αI = .80, and αA = .88 in the second study). Statistical results of Exploratory Factor Analysis in the first sample indicated goodness of fit to a two-factor model (RMSR = .057, GFI = .98). The second study confirmed that factorial structure (χ2/df = 80.50/43 = 1.87, RMSEA = .088, CFI = .94, TLI = .92). Correlations with other measures indicated the Impatience subscale is associated with different expressions of anger behind the wheel, and directly correlated with the loss of driver's license points. Furthermore, the Aggressiveness or Abruptness subscale was associated with more mechanical aspects, and correlated inversely with age. PMID:26610847

  5. Excessive Eating and Compulsive Buying Behaviours in Women: An Empirical Pilot Study Examining Reward Sensitivity, Anxiety, Impulsivity, Self-Esteem and Social Desirability

    Science.gov (United States)

    Davenport, Kate; Houston, James E.; Griffiths, Mark D.

    2012-01-01

    "Mall disorders" such as excessive eating and compulsive buying appear to be increasing, particularly among women. A battery of questionnaires was used in an attempt to determine this association between specific personality traits (i.e., reward sensitivity, impulsivity, cognitive and somatic anxiety, self-esteem, and social desirability) and

  6. Excessive Eating and Compulsive Buying Behaviours in Women: An Empirical Pilot Study Examining Reward Sensitivity, Anxiety, Impulsivity, Self-Esteem and Social Desirability

    Science.gov (United States)

    Davenport, Kate; Houston, James E.; Griffiths, Mark D.

    2012-01-01

    "Mall disorders" such as excessive eating and compulsive buying appear to be increasing, particularly among women. A battery of questionnaires was used in an attempt to determine this association between specific personality traits (i.e., reward sensitivity, impulsivity, cognitive and somatic anxiety, self-esteem, and social desirability) and…

  7. Definition of Impulsivity and Related Terms Following Traumatic Brain Injury: A Review of the Different Concepts and Measures Used to Assess Impulsivity, Disinhibition and other Related Concepts

    Science.gov (United States)

    Kocka, Andrea; Gagnon, Jean

    2014-01-01

    Impulsivity is a common and debilitating sequela following traumatic brain injury (TBI), but there is no consensual definition or measure to assess this construct. The following review aims to elucidate the differences and resemblances between impulsivity, disinhibition and other related terms following brain injury and the instruments that are commonly used to measure these constructs. To do so, a search through different databases was conducted in order to find articles that mention and define impulsivity, disinhibition, impulse control, regulation deficits, dyscontrol and risky behavior. The concepts that stand out from the literature, the measures used, the similarities, the differences between these concepts are observed. The fit with the UPPS model of impulsivity, according to which impulsivity is a multidimensional concept composed of four distinct dimensions (urgency, perseverance, premeditation and sensation-seeking) is discussed. PMID:25431442

  8. Definition of Impulsivity and Related Terms Following Traumatic Brain Injury: A Review of the Different Concepts and Measures Used to Assess Impulsivity, Disinhibition and other Related Concepts

    Directory of Open Access Journals (Sweden)

    Andrea Kocka

    2014-10-01

    Full Text Available Impulsivity is a common and debilitating sequela following traumatic brain injury (TBI, but there is no consensual definition or measure to assess this construct. The following review aims to elucidate the differences and resemblances between impulsivity, disinhibition and other related terms following brain injury and the instruments that are commonly used to measure these constructs. To do so, a search through different databases was conducted in order to find articles that mention and define impulsivity, disinhibition, impulse control, regulation deficits, dyscontrol and risky behavior. The concepts that stand out from the literature, the measures used, the similarities, the differences between these concepts are observed. The fit with the UPPS model of impulsivity, according to which impulsivity is a multidimensional concept composed of four distinct dimensions (urgency, perseverance, premeditation and sensation-seeking is discussed.

  9. Modulatory role of the brain-derived neurotrophic factor Val66Met polymorphism on the effects of serious life events on impulsive aggression in borderline personality disorder.

    Science.gov (United States)

    Wagner, S; Baskaya, O; Dahmen, N; Lieb, K; Tadić, A

    2010-02-01

    Impulsive aggression belongs to the key features of borderline personality disorder (BPD). In the development of BPD, serious life events are known to play a major role. Acute and chronic stress has been suggested to inhibit hippocampal brain-derived neurotrophic factor (BDNF) synthesis and to mediate neural plasticity in response to adverse social experiences. Recently it has been reported that the frequency of violent suicide attempts is higher in adult suicide attempters reporting severe childhood sexual abuse and carrying the Val(66)Val genotype of the BDNF Val(66)Met polymorphism. In this study we analysed modulating effects of BDNF Val(66)Met polymorphism on the effects of physical maltreatment, rape and childhood sexual abuse on impulsive aggression. One hundred and fifty-nine BPD patients from Germany and of Caucasian descent were included. Impulsive aggression was assessed by the Buss-Durkee-Hostility Inventory (BDHI). Childhood sexual abuse accounted for 23.6% of the variance of BDHI sum score. Childhood sexual abuse decreased BDHI sum score in BDNF Val/Val carriers but not in Met carriers. In contrast to previous findings this study analysing a specific gene x environment interaction in BPD patients suggests a decreasing effect of childhood sexual abuse on impulsive aggression in BPD patients, particularly in BDNF Val/Val carriers. The interrelations between serious life events, impulsive aggression and the BDNF Val(66)Met polymorphism as well as their implication for BPD are far from understood and require further investigations. PMID:19817874

  10. Impulse Control and Callous-Unemotional Traits Distinguish Patterns of Delinquency and Substance Use in Justice Involved Adolescents: Examining the Moderating Role of Neighborhood Context.

    Science.gov (United States)

    Ray, James V; Thornton, Laura C; Frick, Paul J; Steinberg, Laurence; Cauffman, Elizabeth

    2016-04-01

    Both callous-unemotional (CU) traits and impulse control are known risk factors associated with delinquency and substance use. However, research is limited in how contextual factors such as neighborhood conditions influence the associations between these two dispositional factors and these two externalizing behaviors. The current study utilized latent class analysis (LCA) to identify unique classes of delinquency and substance use within an ethnically diverse sample (n = 1216) of justice-involved adolescents (ages 13 to 17) from three different sites. Neighborhood disorder, CU traits, and impulse control were all independently associated with membership in classes with more extensive histories of delinquency and substance use. The effects of CU traits and impulse control in distinguishing delinquent classes was invariant across levels of neighborhood disorder, whereas neighborhood disorder moderated the association between impulse control and substance use. Specifically, the probability of being in more severe substance using classes for those low in impulse control was stronger in neighborhoods with fewer indicators of social and physical disorder. PMID:26201308

  11. Cued to Act on Impulse: More Impulsive Choice and Risky Decision Making by Women Susceptible to Overeating after Exposure to Food Stimuli

    OpenAIRE

    Yeomans, Martin R; Brace, Aaron

    2015-01-01

    There is increasing evidence that individual differences in tendency to overeat relate to impulsivity, possibly by increasing reactivity to food-related cues in the environment. This study tested whether acute exposure to food cues enhanced impulsive and risky responses in women classified on tendency to overeat, indexed by scores on the three factor eating questionnaire disinhibition (TFEQ-D), restraint (TFEQ-R) and hunger scales. Ninety six healthy women completed two measures of impulsive ...

  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.

    Science.gov (United States)

    Kolla, Nathan J; Dunlop, Katharine; Downar, Jonathan; Links, Paul; Michael Bagby, R; 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. PMID:26908392

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

    Energy Technology Data Exchange (ETDEWEB)

    Hänninen, Tuomas, E-mail: tuoha@ifm.liu.se; Schmidt, Susann; Jensen, Jens; Hultman, Lars; Högberg, Hans [Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linköping University, Linköping SE-581 83 (Sweden)

    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.

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

    International Nuclear Information System (INIS)

    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

  15. Rapid Vaporization of Thin Conductors Used for Impulse Metalworking

    Science.gov (United States)

    Vivek, Anupam

    Forming, cutting and welding of metal by impulse has significant advantages, in that short time scales change the fundamental nature of the forming process and short duration impulses can be used with much lighter and more agile equipment because large static forces do not need to be resisted. Impulse metalworking is commonly implemented using explosives or electromagnetic actuators. Explosives have limitations such as space requirements, handling and storage restrictions and ability to scale down the process. The application of electromagnetic forming is limited at high energies and large numbers of operations by the availability of long-lived electromagnetic coils (or actuators, as they are sometimes referred to). Here low-cost, disposable actuators have been suggested as one method to treat this issue. Forming, cutting and welding of metal by impulse has significant advantages, in that short time scales change the fundamental nature of the forming process and short duration impulses can be used with much lighter and more agile equipment because large static forces do not need to be resisted. Impulse metalworking is commonly implemented using explosives or electromagnetic actuators. Explosives have limitations such as space requirements, handling and storage restrictions and ability to scale down the process. The application of electromagnetic forming is limited at high energies and large numbers of operations by the availability of long-lived electromagnetic coils (or actuators, as they are sometimes referred to). Here low-cost, disposable actuators have been suggested as one method to treat this issue. Applications including cutting, forming, axisymmetric joining and collision welding are demonstrated and discussed. From analysis of the data from these applications, it was seen that degree of confinement has a great effect on effective geometries of a vaporizing foil. With less confinement, thicker foils were found to be more efficient whereas thinner foils were found to be more effective for the applications which require less confinement pressure on the foil. Collision welding of a wide range of dissimilar metals was implemented and mechanical testing yielded a wide spectrum of results. Optical micrographs of the weld interfaces also showed a wide range of morphology. A device called linear perforator has been created to use the pressure created by vaporizing wire and detonation of a chemical augment surrounding it, to launch a 3.174 mm thick, 25.4 mm tall and 152.4 mm long steel projectile to velocities close to 400 m/s. This projectile is used to fully penetrate 12.7 mm thick artillery shells made of steel. Design of the linear perforator and latest results will be discussed.

  16. Neurobiologia dos transtornos do controle dos impulsos The neurobiology of impulse control disorders

    Directory of Open Access Journals (Sweden)

    Wendol A Williams

    2008-05-01

    Full Text Available OBJETIVO: Revisar os artigos sobre substratos neurobiológicos dos transtornos do controle dos impulsos. O jogo patológico é o foco central desta revisão na medida em que a maioria dos estudos biológicos dos formalmente classificados como transtornos do controle dos impulsos examinou este transtorno. MÉTODO: Foi feita uma busca no banco de dados Medline de artigos publicados de 1966 até o presente para identificar aqueles relevantes para serem revisados neste artigo. DESFECHOS: Estudos pré-clínicos sugerem que a neuromodulação das monoaminas cerebrais está associada à tomada de decisões impulsivas e aos comportamentos de risco. Os estudos clínicos implicam diversos sistemas de neurotransmissores (serotoninérgico, dopaminérgico, adrenérgico e opióide na fisiopatologia do jogo patológico e de outros transtornos do controle dos impulsos. Estudos de neuroimagem preliminares têm indicado o córtex pré-frontal ventromedial e o estriato ventral como atuantes na fisiopatologia do jogo patológico e de outros transtornos do controle dos impulsos. As contribuições genéticas para o jogo patológico parecem substanciais e os estudos iniciais têm relacionado esse transtorno a polimorfismos alélicos específicos, ainda que os achados de varredura genômica ainda tenham que ser publicados. CONCLUSÃO: Mesmo que tenham sido logrados avanços significativos em nossa compreensão sobre os transtornos do controle dos impulsos, mais pesquisas são necessárias para ampliar o conhecimento existente e traduzir esses achados em avanços clínicos.OBJECTIVE: To review the neurobiological substrates of impulse control disorders. Pathological gambling is a main focus of the review in that most biological studies of the formal impulse control disorders have examined this disorder. METHOD: The medical database Medline from 1966 to present was searched to identify relevant articles that were subsequently reviewed to generate this manuscript. RESULTS: Preclinical studies suggest that differential brain monoamine neuromodulation is associated with impulsive decision-making and risk-taking behaviors. Clinical studies implicate multiple neurotransmitter systems (serotonergic, dopaminergic, adrenergic, and opioidergic in the pathophysiology of pathological gambling and other impulse control disorders. Initial neuroimaging studies have implicated the ventromedial prefrontal cortex and ventral striatum in the pathophysiology of pathological gambling and other impulse control disorders. Genetic contributions to pathological gambling seem substantial and initial studies have implicated specific allelic polymorphisms, although genome-wide analyses have yet to be published. CONCLUSION: Although significant advances have been made in our understanding of the neurobiology of impulse control disorders, more research is needed to extend existing knowledge and translate these findings into clinical advances.

  17. Usage of measured reverberation tail in a binaural room impulse response synthesis

    DEFF Research Database (Denmark)

    Markovic, Milos; Olesen, Sren Krarup; Madsen, Esben; Hoffmann, Pablo F.; Hammershi, Dorte

    utilizing correct acoustical properties of the specific environments. Binaural room impulse response (BRIR) synthesis represents one of the main tasks in the binaural auralization. When the BRIRs are simulated, high order reflections (reverberation tail) are usually modeled statistically because of the high...... case and measured late reverberation from the first one. All three cases are evaluated and compared objectively based on the obtained room acoustic parameters as well as subjectively by listening tests....... density of reflections. That can lead to metallic and unnatural sound. Also, room-specific sound envelopment feeling is lost. This paper investigates the possibility of using measured reverberation tail instead of the modeled one in BRIRs synthesis. Three cases are observed. In the first one, BRIRs...

  18. Impulsivity components measured by the Brazilian version of the Barratt Impulsiveness Scale (BIS-11) / Componentes da impulsividade avaliados pela verso brasileira da Barratt Impulsiveness Scale (BIS-11)

    Scientific Electronic Library Online (English)

    Alina Gomide, Vasconcelos; Maycoln Leni Martins, Teodoro; Leandro, Malloy-Diniz; Humberto, Correa.

    2015-03-01

    Full Text Available O objetivo principal desse estudo foi investigar as caractersticas psicomtricas da Barratt Impulsiveness Scale (BIS-11). A anlise do contedo dos itens foi realizada por sete doutorandos. A amostra foi composta por 897 estudantes submetidos a BIS-11 e a medidas de autorrelato sobre a presena de [...] sintomas de Transtorno Mental Comum e TDAH, uso de lcool e tabagismo. A idade mdia foi de 27,32 (DP=8,69) anos, 56% eram mulheres e 52% tinham educao superior incompleta. Anlises de contedo e fatorial indicaram que a impulsividade representada mais adequadamente por dois fatores denominados dificuldade de planejamento e controle inibitrio. Concordncia teste-reteste indicou que os escores se mantiveram estveis aps sete meses. Adicionalmente, os escores da BIS-11 discriminaram os indivduos em termos de tabagismo e sintomas psicopatolgicos, indicando evidncias de validade de critrio. A discusso dos resultados foi baseada no modelo neuropsicolgico dos componentes quentes e frios das funes executivas. Abstract in english The main purpose of this study was to investigate the psychometric properties of the Barratt Impulsiveness Scale (BIS-11). Content item analysis was conducted by seven doctoral students. A convenience sample of 897 students was submitted to BIS-11 and they also filled self-reports about Minor Mental [...] Disorder and ADHD symptoms, alcohol use and cigarette smoking. Mean age was 27.32 (SD=8.69) years, 56% were female and 52% had incomplete college degree. Content and factorial analyses revealed that impulsivity was best represented by two latent factors labeled non-planning and inhibition behaviors. Test retest agreement tended to produce similar score patterns seven months after the first evaluation. Additionally, BIS-11 scores discriminated subjects in terms of cigarette smoking and psychopathological symptoms, which indicated evidences regarding criterion-related validity. The theoretical discussion was present based on the neuropsychological model of hot and cool aspects of executive function.

  19. The mediating role of anger in the relationship between PTSD symptoms and impulsivity.

    Science.gov (United States)

    Contractor, Ateka A; Armour, Cherie; Wang, Xin; Forbes, David; Elhai, Jon D

    2015-03-01

    Research indicates a significant relationship between posttraumatic stress disorder (PTSD) and anger (Olatunji, Ciesielski, & Tolin, 2010; Orth & Wieland, 2006). Individuals may seek urgent coping to deal with the distress of anger, which is a mobilizing and action-oriented emotion (Novaco & Chemtob, 2002); possibly in the form of impulsive actions consistent with impulsivity's association with anger (Milligan & Waller, 2001; Whiteside & Lynam, 2001). This could be 1 of the explanations for the relationship between PTSD and impulsivity (Kotler, Julian, Efront, & Amir, 2001; Ledgerwood & Petry, 2006). The present study assessed the mediating role of anger between PTSD (overall scores and subscales of arousal and negative alterations in mood/cognitions) and impulsivity, using gender as a covariate of impulsivity. The PTSD Checklist for Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5), Dimensions of Anger Reaction scale-5, and the UPPS Impulsivity Scale were administered to a sample of 244 undergraduate students with a trauma history. Results based on 1000 bootstrapped samples indicated significant direct effects of PTSD (overall and 2 subscales) on anger, of anger on impulsivity, and of PTSD (overall and 2 subscales) on impulsivity. Further, anger significantly mediated the relationship between PTSD (overall and 2 subscales) and impulsivity, consistent with the hypothesized models. Results suggest that impulsivity aims at coping with distressing anger, possibly explaining the presence of substance usage, and other impulsive behaviors in people with PTSD. Further, anger probably serves as a mobilizing and action-oriented emotion coupled with PTSD symptoms. PMID:25793689

  20. A risk and maintenance model for bulimia nervosa: From impulsive action to compulsive behavior.

    Science.gov (United States)

    Pearson, Carolyn M; Wonderlich, Stephen A; Smith, Gregory T

    2015-07-01

    This article offers a new model for bulimia nervosa (BN) that explains both the initial impulsive nature of binge eating and purging, as well as the compulsive quality of the fully developed disorder. The model is based on a review of advances in research on BN and advances in relevant basic psychological science. It integrates transdiagnostic personality risk, eating-disorder-specific risk, reinforcement theory, cognitive neuroscience, and theory drawn from the drug addiction literature. We identify both a state-based and a trait-based risk pathway, and we then propose possible state-by-trait interaction risk processes. The state-based pathway emphasizes depletion of self-control. The trait-based pathway emphasizes transactions between the trait of negative urgency (the tendency to act rashly when distressed) and high-risk psychosocial learning. We then describe a process by which initially impulsive BN behaviors become compulsive over time, and we consider the clinical implications of our model. (PsycINFO Database Record PMID:25961467