WorldWideScience

Sample records for specific impulse magnetoplasma

  1. An Injector for the Variable Specific Impulse Magnetoplasma Rocket

    Science.gov (United States)

    Glover, T. W.; Chang-Diaz, F. R.; Squire, J. P.; Chan, A. A.

    1997-11-01

    We present a summary of progress on the development of a plasma injector for NASA's VASIMR (Variable Specific Impulse Magnetoplasma Rocket) engine. The plasma rocket constrains a flowing plasma in an asymmetric magnetic bottle and exhausts it through a magnetic nozzle to produce thrust. The injector is a plasma source located on the axis of symmetry, forward of the series of coils forming the constraining magnetic field. The injector is intended to produce a well-collimated jet of highly ionized plasma which will enter the central cell of the machine through its forward mirror. The prototype design is based on that of a Lorentz Force Accelerator developed as a thruster by the electric propulsion research group at Princeton. Our investigation focuses on the effects of the rocket's magnetic field on the operation of the injector, the effect of a local magnetic field on the discharge behavior, and the effectiveness of discharge initiation by glow discharge versus initiation by ECRH. We evaluate the performance of this prototype injector by comparing the characteristics of the plasma it inserts into the central cell of the engine with the characteristics called for in the design of the plasma rocket.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ilin, A.V. [Lockheed Martin Space Mission Systems and Services, Houston, TX (United States); Diaz, F.R.C.; Squire, J.P. [JSC/NASA, Houston, TX (United States). Advanced Space Propulsion Lab.; Carter, M.D. [Oak Ridge National Lab., TN (United States)

    1999-01-01

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

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

    International Nuclear Information System (INIS)

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

  4. 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.

  5. 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...

  6. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-01-01

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

  8. Chaos in Magnetoplasmas

    Directory of Open Access Journals (Sweden)

    B. Buti

    1999-01-01

    Full Text Available A nonlinear wave, in general, is equivalent to a nonlinear dynamical system, which exhibits the phenomena of chaos. By means of techniques of nonlinear dynamical systems, we have investigated the conditions under which nonlinear Alfvén waves and lower-hybrid waves can become chaotic. The role of heavy ions, in controlling the chaos in magnetoplasmas, is examined. Chaotic routes to Alfvénic turbulence, with k-1 spectra, are observed in case of externally driven nonlinear Alfvén waves. Anomalous heating and particle acceleration resulting from chaotic fields, generated by lower-hybrid waves, are briefly outlined.

  9. HTS Magnets for Advanced Magnetoplasma Space Propulsion Applications

    Energy Technology Data Exchange (ETDEWEB)

    Carte, M.D.; Chang-Diaz, F.R. Squire, J.P.; Schwenterly, S.W.

    1999-07-12

    Plasma rockets are being considered for both Earth-orbit and interplanetary missions because their extremely high exhaust velocity and ability to modulate thrust allow very efficient use of propellant mass. In such rockets, a hydrogen or helium plasma is RF-heated and confined by axial magnetic fields produced by coils around the plasma chamber. HTS coils cooled by the propellant are desirable to increase the energy efficiency of the system. We describe a set of prototype high-temperature superconducting (HTS) coils that are being considered for the VASIMR ( Variable Specific Impulse Magnetoplasma Rocket) thruster proposed for testing on the Radiation Technology Demonstration (RTD) satellite. Since this satellite will be launched by the Space Shuttle, for safety reasons liquid helium will be used as propellant and coolant. The coils must be designed to operate in the space environment at field levels of 1 T. This generates a unique set of requirements. Details of the overall winding geometry and current density, as well as the challenging thermal control aspects associated with a compact, minimum weight design will be discussed.

  10. Dynamics of specific heat and other relaxation processes in supercooled liquids by impulsive stimulated scattering

    International Nuclear Information System (INIS)

    Laser based impulsive stimulated scattering or transient grating excitation in a heterodyne diffraction scheme is a powerful method to extract information about different relaxing properties from different signal contributions. Longitudinal acoustic waves are detected simultaneously with thermal expansion and thermal diffusion. Careful fitting of the time-domain density response at different temperatures makes it possible to obtain the various relaxing physical parameters, and to construct Arrhenius plots for the respective relaxation processes. In this work we focus on the influence of the specific heat capacity C on the slower part of the density response function S?(t), and, inversely, on the possibility to extract from experimental S?(t) data the relaxation behaviour C(?). The specific heat capacity is relevant for both the initially rising part of the impulsive stimulated scattering signal (together with the time and frequency dependent thermal expansion ?(t)), and for the thermal diffusion dominated decrease of the signal at later times after the excitation. By simulating S?(t) data in different scenarios, we address the feasibility of unravelling the impulse response functions C(t) and ?(t) (and via Fourier transform also C(?) and ?(?)) by careful fitting of the signal. This approach offers a unique possibility to extend the 100 kHz bandwidth of current dynamic calorimetric techniques determining C(?) (photopyroelectric spectroscopy) to the sub-GHz range.

  11. 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 200glycidyl 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 ?v of 17.5 km/s to the spacecraft in sixteen months.

  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. The Effect of High Concentration Guanidinium Azo-Tetrazolate on Thrust and Specific Impulse of a Hybrid Rocket

    Science.gov (United States)

    Tilahun, Dagim; Wright, A.; Foley, P.; Reason, M.

    2001-04-01

    A thrust and impulse study of the hybrid rocket fuel additive, Guanidinium Azo-Tetrazolate (GAT), was conducted at the University of Arkansas at Little Rock (UALR) Hybrid Rocket Facility. GAT is an organic salt with a high percentage of nitrogen. GAT was mixed with the standard hybrid rocket fuel, Hydroxyl-Terminated Polybutadiene (HTPB), in concentrations of 15% and 25%, by mass. The fuel grains with the GAT additive were fired for 4 second runs with oxygen flows of 0.04, 0.06, 0.08, and 0.10 lbm/sec. For each run, average thrust, standard deviation of thrust, total impulse, and specific impulse were measured. Average thrust, standard deviation of thrust, specific impulse and total impulse vs. oxygen flow were plotted. Similar data was collected for plain HTPB/PAPI fuels for comparison. GAT is found to increase the thrust output when added to the standard hybrid rocket fuel, HTPB. 25% GAT fuel produced approximately the same thrust as the 15% GAT fuel. Specific impulse was slightly lower with both 15% and 25% GAT fuels. Standard Deviation of thrust was used as a crude measure of amplitude of oscillations during combustion. GAT-added fuels showed a limited decrease in thrust oscillation amplitude.

  14. 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 ?v of 17.5 km/s to the spacecraft in sixteen months

  15. 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.

  16. 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 ?v of 17.5 km/s to the spacecraft in sixteen months. Its specific impulse will be adjustable over the range 200specific impulse for each mission segment. We see no reason why Isp = 10,000 seconds cannot be achieved with liquid fuels.

  17. Stationary Double Layers in a Collisionless Magnetoplasma

    DEFF Research Database (Denmark)

    Noriyoshi, Sato; Mieno, Tetsu; Hatakeyama, Rikizo; Iizuka, Satoru; Saeki, Koichi; Juul Rasmussen, Jens; Michelsen, Poul; Schrittwieser, Roman

    1983-01-01

    Stationary double layers are generated in a magnetoplasma by applying potential differences between two heated plates on which the plasma is produced by surface ionization. By measuring the double-layer formation process, a localized potential drop is found to be formed initially in front of the plate on the low-potential side, being accompanied with current limitation. This localized potential drop moves along the plasma column, but finally stops and results in the formation of the stationary d...

  18. 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 pro

  19. 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.

  20. 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.

  1. 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

    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 their decision making to gather more information in a condition with a conflict between reward and certainty. The reduced information sampling may also reflect an increased conviction in the decision at a point of relative uncertainty.

  2. 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)

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

    OpenAIRE

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

    2008-01-01

    Recent advances in personality theory indicate that there are distinct constructs that dispose individuals to rash action and risky behavior, as opposed to one broad trait of impulsivity. Two are emotion based, two represent deficits in conscientiousness, and one is sensation seeking. Previous studies of impulsivity and its relationship to bulimia nervosa have yielded mixed findings. The authors applied this advance in personality theory to the study of bulimia nervosa (BN) to test the hypoth...

  4. Whistler waves guided by density depletion ducts in a magnetoplasma

    Science.gov (United States)

    Bakharev, P. V.; Zaboronkova, T. M.; Kudrin, A. V.; Krafft, C.

    2010-11-01

    The guided propagation of whistler waves along cylindrical density depletion ducts in a magneto-plasma is studied. It is shown that, under certain conditions, such ducts can support volume and surface eigenmodes. The dispersion properties and field structure of whistler modes guided by density depletion ducts are analyzed. The effect of collisional losses in the plasma on the properties of modes is discussed.

  5. Specific dimensions of impulsivity are differentially associated with daily and non-daily cigarette smoking in young adults.

    Science.gov (United States)

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

    2015-07-01

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

  6. Ultrastrong Stationary Double Layers in a Nondischarge Magnetoplasma

    DEFF Research Database (Denmark)

    Sato, N.; Hatakeyama, R.; Iizuka, S.; Mieno, T.; Saeki, K.; Juul Rasmussen, Jens; Michelsen, Poul

    1981-01-01

    Ultrastrong stationary double layers are generated in a magnetoplasma by simply applying potential differences between two plasma sources. The potential drop ?D of the double layer is increased up to e?D/Te?2×103 (Te is the electron temperature in eV) with no difficulties caused by gas discharge. There are always large spiky fluctuations on the low-potential tail of the double layers.

  7. 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.

  8. 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...

  9. Compression zone formation in magnetoplasma compressor operating with heavy gases

    International Nuclear Information System (INIS)

    Present work is devoted to experimental investigations of the plasma compression zone dynamics and its influence on radiation characteristics. The construction of magneto-plasma compressor (MPC) of compact geometry with conical copper electrodes is described. Comprehensive information about dynamics of compression zone formation, it position, plasma parameters and geometric dimensions was obtained using spectral diagnostics. Plasma stream density ? 1018cm-3 was measured by Stark broadening of Xe spectral lines. Electron temperature 5...7 eV was estimated using the ratio of Xe lines intensities. EUV radiation intensity was detected by registration system consisting on absolutely calibrated AXUV diodes with integrated thin-films filter for different wavelength ranges and multi-layered MoSi mirrors. Spatial distributions of electrical currents has been performed also.

  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. 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.

  12. Dissipative drift wave instability in a radially bounded nonuniform dusty magnetoplasma

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, P.K., E-mail: pshukla@ucsd.edu [International Centre for Advanced Studies in Physical Sciences, Faculty of Physics and Astronomy, Ruhr University Bochum, D-44780 Bochum (Germany); Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093 (United States); Rosenberg, M., E-mail: rosenber@ecepops.ucsd.edu [Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA 92093 (United States)

    2012-02-27

    Properties of the dissipative drift wave instability in a radially bounded nonuniform dusty magnetoplasma are investigated. By using the two-fluid model for the electrons and ions, we derive a nonlocal wave equation for the low-frequency collisional drift wave in the bounded system. The charged dust is assumed to be immobile on the time scale of the instability. The wave equation admits a dispersion relation, which exhibits the modification of the drift wave frequency and the dissipative drift wave instability growth rate due to radial boundaries. Possible application of our investigation to forthcoming nonuniform dusty magnetoplasma experiments is discussed.

  13. Drift wave instability in a radially bounded dusty magnetoplasma with parallel ion velocity shear

    Science.gov (United States)

    Shukla, P. K.; Rosenberg, M.; Rosenberg

    2013-02-01

    Properties of the coupled dust ion-acoustic drift wave instability in a radially bounded dusty magnetoplasma with an equilibrium sheared parallel ion (SPI) flow are investigated. By using the two-fluid model for the electrons and ions, a wave equation for the low-frequency coupled dust ion-acoustic drift waves in a bounded plasma with stationary charged dust grains is derived. The wave equation admits a linear dispersion relation, which exhibits that the radial boundary affects the growth rate of the coupled ion-acoustic drift wave instability which is excited by the SPI flow. The results should be relevant to dusty magnetoplasma experiments with an SPI flow.

  14. Excitation of electromagnetic waves by a pulsed loop antenna in a magnetoplasma

    Energy Technology Data Exchange (ETDEWEB)

    Kudrin, Alexander V.; Shmeleva, Natalya M. [Department of Radiophysics, University of Nizhny Novgorod, 23 Gagarin Ave., Nizhny Novgorod 603950 (Russian Federation); Ferencz, Orsolya E. [Department of Geophysics and Space Sciences, Space Research Group, Eoetvoes University, Pazmany P. s. I./A., Budapest H-1117 (Hungary); Zaboronkova, Tatyana M. [Department of Nuclear Physics, Technical University of Nizhny Novgorod, 24 Minin St., Nizhny Novgorod 603950 (Russian Federation)

    2012-06-15

    A study is made of the radiation from a pulsed loop antenna immersed in a cold collisionless magnetoplasma. Using a rigorous solution for the total field of such an antenna, the energy characteristics of its radiation are determined. The radiated energy and its distribution over the spatial and frequency spectra of the excited waves are analyzed as functions of the antenna and plasma parameters. Numerical results referring to the case where the frequency spectrum of the antenna current is concentrated in the whistler frequency range are reported. The results obtained can be useful in understanding the basic features of wave excitation by pulsed sources in a magnetoplasma.

  15. 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

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

    Science.gov (United States)

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

    2011-01-01

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

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

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Nowakowska-Langier, Katarzyna, E-mail: k.nowakowska-langier@ncbj.gov.pl [Material Physics Department, National Centre for Nuclear Research, A. Soltana 7, 05-400 Otwock-Swierk (Poland); Chodun, Rafal [Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warsaw (Poland); Nietubyc, Robert [Material Physics Department, National Centre for Nuclear Research, A. Soltana 7, 05-400 Otwock-Swierk (Poland); Minikayev, Roman [Institute of Physics, Polish Academy of Sciences, Lotnikow 32/46, 02-668 Warsaw (Poland); Zdunek, Krzysztof [Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warsaw (Poland); Material Physics Department, National Centre for Nuclear Research, A. Soltana 7, 05-400 Otwock-Swierk (Poland)

    2013-06-15

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

  19. 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...

  20. Splitting of surface polariton dispersion curves due to resonance with magnetoplasma transition layer

    Science.gov (United States)

    Kushwaha, M. S.; Halevi, P.

    1987-12-01

    We study magnetoplasma polaritons of a thin semiconductor film on a polar-semiconductor substrate. In the vicinity of the hybrid cyclotron-plasmon frequency the surface-phonon polariton dispersion curve exhibits a splitting. The repulsion between the upper and lower branches depends on the intensity of the applied magnetic field. We have considered propagation in directions that are parallel or perpendicular to the magnetic field (itself parallel to the thin film) and find a strong directional effect.

  1. 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.

  2. Laboratory modeling of the interaction of electron beams with a magnetoplasma

    Science.gov (United States)

    Starodubtsev, M. V.; Krafft, C.

    2010-12-01

    We present the results of laboratory experiments in which the mechanisms of interaction of electron beams with whistler waves in a magnetoplasma are studied. Different mechanisms of whistler generation during the injection of a modulated electron beam in the plasma are studied, and the mechanism of conversion of the beam kinetic energy to radiation is demonstrated. The processes of whistler wave generation by the modulated beam at the ? Cerenkov and Doppler resonances are analyzed in detail. The excitation of whistler waves by means of a nonresonant mechanism of the transition radiation is studied.

  3. Three dimensional electrostatic solitary waves in a dense magnetoplasma with relativistically degenerate electrons

    International Nuclear Information System (INIS)

    In this paper, small but finite amplitude electrostatic solitary waves in a relativistic degenerate magnetoplasma, consisting of relativistically degenerate electrons and non-degenerate cold ions, are investigated. The Zakharov-Kuznetsov equation is derived employing the reductive perturbation technique and its solitary wave solution is analyzed. It is shown that only compressive electrostatic solitary structures can propagate in such a degenerate plasma system. The effects of plasma number density, ion cyclotron frequency, and direction cosines on the profiles of ion acoustic solitary waves are investigated and discussed at length. The relevance of the present investigation vis-a-vis pulsating white dwarfs is also pointed out

  4. Ion-acoustic solitons in warm magnetoplasmas with super-thermal electrons

    CERN Document Server

    Choudhury, B; Das, G C; Bora, M P

    2012-01-01

    In this work, the phenomenon of formation of localised electrostatic waves (ESW) or soliton is considered in a warm magnetoplasma with the possibility of non-thermal electron distribution. The parameter regime considered here is relevant in case of magnetospheric plasmas. We show that deviation from a usual relaxed Maxwellian distribution of the electron population has a significant bearing in the allowed parameter regime, where these ESWs can be found. We further consider the presence of more than one electron temperature, which is inspired by recent space-based observations[key-2].

  5. 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.

  6. Symmetry analysis and similarity electrostatic waves in a nonuniform dusty magnetoplasma

    International Nuclear Information System (INIS)

    We apply the group theory to a (3+1)-dimensional nonlinear system relevant for the low-frequency electrostatic waves in a nonuniform dusty magnetoplasma. In correspondence with the generators of the symmetry group allowed by the system, new types of similarity reductions are performed. Some new exact solutions are obtained, which can be in the form of solitary waves, shock waves and periodic waves. Especially, our solutions indicate that the system may have time-dependent nonlinear shears. Some explicit similarity electrostatic wave solutions with time periodic nonlinear shears are displayed graphically

  7. Three dimensional electrostatic solitary waves in a dense magnetoplasma with relativistically degenerate electrons

    Science.gov (United States)

    Ata-ur-Rahman; Masood, W.; Eliasson, B.; Qamar, A.

    2013-09-01

    In this paper, small but finite amplitude electrostatic solitary waves in a relativistic degenerate magnetoplasma, consisting of relativistically degenerate electrons and non-degenerate cold ions, are investigated. The Zakharov-Kuznetsov equation is derived employing the reductive perturbation technique and its solitary wave solution is analyzed. It is shown that only compressive electrostatic solitary structures can propagate in such a degenerate plasma system. The effects of plasma number density, ion cyclotron frequency, and direction cosines on the profiles of ion acoustic solitary waves are investigated and discussed at length. The relevance of the present investigation vis-a-vis pulsating white dwarfs is also pointed out.

  8. Ballistic impulse gauge

    Science.gov (United States)

    Ault, Stanley K. (Antioch, CA)

    1993-01-01

    A gauge for detecting the impulse generated in sample materials by X-rays or other impulse producing mechanisms utilizes a pair of flat annular springs to support a plunger relative to a housing which may itself be supported by a pair of flat annular springs in a second housing. The plunger has a mounting plate mounted on one end and at the other, a position or velocity transducer is mounted. The annular springs consist of an outer ring and an inner ring with at least three arcuate members connecting the outer ring with the inner ring.

  9. On transverse electric (TE) wave propagation in a warm moving magnetoplasma with sinusoidal electron-density distribution

    International Nuclear Information System (INIS)

    It has been shown, using the first three moment equations in conjunction with Maxwell's equations, that the wave equation for the TE mode in a warm moving stratified magnetoplasma transforms, for an assumed sinusoidal distribution of the electron density, to the standard form of the Hill's differential equation. (Auth.)

  10. 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.

  11. 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 (Møller, Mott) when the distance of closest approach is larger than the Compton wavelength of the particle. Magnetism emerges as a consequence of viewing retarded and advanced interactions from the vantage point of an instantaneous radius vector. Radiation reaction becomes the local conservation of energy-momentum between the radiating particle and the emitted impulse. A net action is defined that could be used in developing quantum dynamics without potentials. A reinterpretation of Newton's laws extends them to relativistic motion. PMID:21929132

  12. 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.

  13. Modified screening potential in a high density inhomogeneous quantum dusty magnetoplasma

    International Nuclear Information System (INIS)

    The effect of strong ambient static magnetic field on Shukla-Nambu-Salimullah (SNS) potential in a dusty quantum magnetoplasma has been investigated using quantum hydrodynamic model. The potential is significantly modified by quantum statistical effects, density inhomogeneity, and dust polarization drift effect. The effective length of the modified SNS potential is found to be a sensitive function of external static magnetic field, ExB0 drift, and the scale length of inhomogeneity. Here E is the electric polarization vector produced via density inhomogeneity, and B0 is the ambient static magnetic field. It is found that dust polarization drift effect predominates the ion polarization drift effect in high magnetic field environments. It attracts our attention to the careful study of the underlying physics of dusty plasma environment of neutron stars and magnetars.

  14. On the instability of electrostatic waves in a nonuniform electron-positron magnetoplasma

    Energy Technology Data Exchange (ETDEWEB)

    El-Taibany, W.F. [Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)], E-mail: eltaibany@hotmail.com; Moslem, W.M. [Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)], E-mail: wmmoslem@hotmail.com; Wadati, Miki [Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)], E-mail: wadati@rs.kagu.tus.ac.jp; Shukla, P.K. [Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)], E-mail: ps@tp4.rub.de

    2008-05-26

    The dispersion properties of three-dimensional electrostatic waves in a nonuniform electron-positron (EP) magnetoplasma are analyzed. A new dispersion relation is derived by use of the electron and positron density responses arising from the electron and positron continuity and Poisson equations. In the local approximation, the dispersion relation admits two wave modes with different velocities. The growth rates of various modes are illustrated both analytically and numerically. Considering the temperature gradients produces a linearly stable transverse mode. The growth rate of the slow mode instability due to the density inhomogeneity only is the highest one, though it appears at higher thermal energy. The angle of the wave propagation affects drastically on the instability features in each case. The applications of the present analysis are briefly discussed.

  15. Electron acoustic wave driven vortices with non-Maxwellian hot electrons in magnetoplasmas

    Energy Technology Data Exchange (ETDEWEB)

    Haque, Q. [Theoretical Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); National Center for Physics Shahdrah Valley Road, Islamabad 44000 (Pakistan); Mirza, Arshad M. [Theoretical Plasma Physics Group, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Zakir, U. [Institute of Physics and Electronics, University of Peshawar, and Khyber Pakhtun Khwa 25000 (Pakistan); Department of Physics, University of Malakand Chakdara Dir(L), Khyber Pakhtun Khwa 18800 Pakistan (Pakistan)

    2014-07-15

    Linear dispersion characteristics of the Electron Acoustic Wave (EAW) and the corresponding vortex structures are investigated in a magnetoplasma in the presence of non-Maxwellian hot electrons. In this regard, kappa and Cairns distributed hot electrons are considered. It is noticed that the nonthermal distributions affect the phase velocity of the EAW. Further, it is found that the phase velocity of EAW increases for Cairns and decreases for kappa distributed hot electrons. Nonlinear solutions in the form of dipolar vortices are also obtained for both stationary and non-stationary ions in the presence of kappa distributed hot electrons and dynamic cold electrons. It is found that the amplitude of the nonlinear vortex structures also reduces with kappa factor like the electron acoustic solitons.

  16. 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.

  17. Bifurcations of nonlinear ion-acoustic travelling waves in a multicomponent magnetoplasma with superthermal electrons

    Science.gov (United States)

    Selim, M. M.; El-Depsy, A.; El-Shamy, E. F.

    2015-12-01

    Properties of nonlinear ion-acoustic travelling waves propagating in a three-dimensional multicomponent magnetoplasma system composed of positive ions, negative ions and superthermal electrons are considered. Using the reductive perturbation technique (RPT), the Zkharov-Kuznetsov (ZK) equation is derived. The bifurcation theory of planar dynamical systems is applied to investigate the existence of the solitary wave solutions and the periodic travelling wave solutions of the resulting ZK equation. It is found that both compressive and rarefactive nonlinear ion-acoustic travelling waves strongly depend on the external magnetic field, the unperturbed positive-to-negative ions density ratio, the direction cosine of the wave propagation vector with the Cartesian coordinates, as well as the superthermal electron parameter. The present model may be useful for describing the formation of nonlinear ion-acoustic travelling wave in certain astrophysical scenarios, such as the D and F-regions of the Earth's ionosphere.

  18. Are Self-Injurers Impulsive?

    OpenAIRE

    Janis, Irene Belle; Nock, Matthew K

    2009-01-01

    Common clinical wisdom suggests that people who engage in self-injury are impulsive. However, virtually all prior work in this area has relied on individuals’ self-report of impulsiveness, despite evidence that people are limited in their ability to accurately report on cognitive processes that occur outside awareness. To address this knowledge gap, we used performance-based measures of several dimensions of impulsiveness to assess whether people engaging in non-suicidal self-injury (NSSI) ...

  19. Phase matching for third-harmonic generation in collisional magnetoplasmas

    International Nuclear Information System (INIS)

    This paper presents a derivation of the phase-matching conditions for generation of the third-harmonic (3?1) and combination frequencies (?1+2?2), by two fundamental electromagnetic waves of frequencies ?1 and ?2, propagating in the extraordinary mode along a magnetic field in a collisional plasma. Expressions for the corresponding optimum distance of propagation for maximum output and the associated values of the phase functions have been derived. In the case of the third-harmonic generation phase matching occurs when the gyrofrequency of the electrons is twice the wave frequency (for all values of plasma frequency). In the case of the combination frequencies, the phase-matching condition is represented by an expression for plasma frequency ?p in terms of the wave frequencies ?1, ?2 and the gyrofrequency ?c of electrons. Furthermore, it is seen that in the (?c/?1)-(?2/?1) plane, phase matching occurs in a narrow region; for every point in this region, there is a corresponding value of (?p/?1). The dependence of optimum distance of propagation and the corresponding value of the phase function on electron collision frequency ?av/?1 have been graphically illustrated for a specific case. An estimate of the maximum value of the third-harmonic conversion efficiency has also been made

  20. A comparison of parametric decay of oblique Langmuir wave in high and low density magneto-plasmas

    International Nuclear Information System (INIS)

    The parametric decay instability of an obliquely propagating Langmuir wave into the low-frequency electromagnetic shear Alfven wave and the Left-Handed Circularly Polarized wave has been investigated in an electron-ion plasma, immersed in a uniform external magnetic field. Quantum magneto-hydrodynamic model has been used to find the linear and non-linear response of a high density quantum magneto-plasma. Going to the classical limit (??0) retrieves the results for low density classical plasma. Nonlinear dispersion relations and growth rates are derived with analytically and numerically. It is observed that growth rate in the high density degenerate magneto-plasma increases exponentially, while in the low density classical case it increases logarithmically

  1. A comparison of parametric decay of oblique Langmuir wave in high and low density magneto-plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Shahid, M.; Hussain, A. [Salam Chair in Physics, Government College University, Lahore-54000 (Pakistan); Department of Physics, Government College University, Lahore-54000 (Pakistan); Murtaza, G. [Salam Chair in Physics, Government College University, Lahore-54000 (Pakistan)

    2013-09-15

    The parametric decay instability of an obliquely propagating Langmuir wave into the low-frequency electromagnetic shear Alfven wave and the Left-Handed Circularly Polarized wave has been investigated in an electron-ion plasma, immersed in a uniform external magnetic field. Quantum magneto-hydrodynamic model has been used to find the linear and non-linear response of a high density quantum magneto-plasma. Going to the classical limit (??0) retrieves the results for low density classical plasma. Nonlinear dispersion relations and growth rates are derived with analytically and numerically. It is observed that growth rate in the high density degenerate magneto-plasma increases exponentially, while in the low density classical case it increases logarithmically.

  2. Multi-dimensional instability of obliquely propagating ion acoustic solitary waves in electron-positron-ion superthermal magnetoplasmas

    Energy Technology Data Exchange (ETDEWEB)

    EL-Shamy, E. F., E-mail: emadel-shamy@hotmail.com [Department of Physics, Faculty of Science, Damietta University, New Damietta 34517, Egypt and Department of Physics, College of Science, King Khalid University, Abha P.O. 9004 (Saudi Arabia)

    2014-08-15

    The solitary structures of multi–dimensional ion-acoustic solitary waves (IASWs) have been considered in magnetoplasmas consisting of electron-positron-ion with high-energy (superthermal) electrons and positrons are investigated. Using a reductive perturbation method, a nonlinear Zakharov-Kuznetsov equation is derived. The multi-dimensional instability of obliquely propagating (with respect to the external magnetic field) IASWs has been studied by the small-k (long wavelength plane wave) expansion perturbation method. The instability condition and the growth rate of the instability have been derived. It is shown that the instability criterion and their growth rate depend on the parameter measuring the superthermality, the ion gyrofrequency, the unperturbed positrons-to-ions density ratio, the direction cosine, and the ion-to-electron temperature ratio. Clearly, the study of our model under consideration is helpful for explaining the propagation and the instability of IASWs in space observations of magnetoplasmas with superthermal electrons and positrons.

  3. Facets of impulsivity interactively predict body fat and binge eating in young women.

    Science.gov (United States)

    Meule, Adrian; Platte, Petra

    2015-04-01

    Impulsivity has been positively linked to overeating and obesity, but findings are inconsistent. Studies using the Barratt Impulsiveness Scale (BIS) show that measures of overeating appear to be most consistently associated with scores on the subscale attentional impulsivity in both non-clinical and clinical samples. Additionally, individuals with binge-eating behaviors may have elevated scores on the subscale motor impulsivity. In the current study, young women (N?=?133) completed the short form of the BIS (BIS-15), the Eating Disorder Examination - Questionnaire, and height, weight and body composition were measured. Regression analyses showed that attentional and motor impulsivity positively predicted binge eating and general eating pathology, while non-planning impulsivity negatively predicted these variables. Moreover, attentional and motor impulsivity interactively predicted percent body fat, and the number of subjective and objective binge episodes. Results show that only specific aspects of trait impulsivity (attentional and motor impulsivity) are positively associated with body mass and binge eating. Non-planning impulsivity appears to be unrelated or even inversely related to those variables, at least in female students. Elevated levels of attentional impulsivity in conjunction with high motor impulsivity may be a risk factor for overweight and clinically relevant binge eating. PMID:25582417

  4. 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

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

    OpenAIRE

    Kayir, Hakan; Semenova, Svetlana; Markou, Athina

    2013-01-01

    Impulsive choice, a form of impulsivity, is associated with tobacco smoking in humans. Trait impulsivity may be a vulnerability factor for smoking, or smoking may lead to impulsive behaviors. We investigated the effects of 14-day nicotine exposure (6.32 mg/kg/day base, subcutaneous minipumps) and spontaneous nicotine withdrawal on impulsive choice in low impulsive (LI) and high impulsive (HI) rats. Impulsive choice was measured in the delayed reward task in which rats choose between a small i...

  6. 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 ? 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.

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

    International Nuclear Information System (INIS)

    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 ? 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

  8. The effects of violence exposure on the development of impulse control and future orientation across adolescence and early adulthood: Time-specific and generalized effects in a sample of juvenile offenders.

    Science.gov (United States)

    Monahan, Kathryn C; King, Kevin M; Shulman, Elizabeth P; Cauffman, Elizabeth; Chassin, Laurie

    2015-11-01

    Impulse control and future orientation increase across adolescence, but little is known about how contextual factors shape the development of these capacities. The present study investigates how stress exposure, operationalized as exposure to violence, alters the developmental pattern of impulse control and future orientation across adolescence and early adulthood. In a sample of 1,354 serious juvenile offenders, higher exposure to violence was associated with lower levels of future orientation at age 15 and suppressed development of future orientation from ages 15 to 25. Increases in witnessing violence or victimization were linked to declines in impulse control 1 year later, but only during adolescence. Thus, beyond previous experiences of exposure to violence, witnessing violence and victimization during adolescence conveys unique risk for suppressed development of self-regulation. PMID:26439073

  9. 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

  10. Impulse control in pigeons.

    Science.gov (United States)

    Ainslie, G W

    1974-05-01

    Pigeons were given a small, immediate food reinforcement for pecking a key, and a larger, delayed reinforcement for not pecking this key. Most subjects pecked the key on more than 95% of trials. However, when pecking a differently colored key at an earlier time prevented this option from becoming available, three of 10 subjects consistently pecked it, thereby forcing themselves to wait for the larger reward. They did not peck the earlier key when it did not prevent this option. This is an experimental example of psychological impulse and a learnable device to control it. Although only a minority of the subjects learned it, the fact that such learning is possible at all argues for a theory of delayed reward that can predict change of preference as a function of elapsing time. PMID:16811760

  11. Neurobiological mechanisms for impulsive-aggression: the role of MAOA.

    Science.gov (United States)

    Dorfman, Hayley M; Meyer-Lindenberg, Andreas; Buckholtz, Joshua W

    2014-01-01

    Aggression may be present across a large part of the spectrum of psychopathology, and underlies costly criminal antisocial behaviors. Human aggression is a complex and underspecified construct, confounding scientific discovery. Nevertheless, some biologically tractable subtypes are apparent, and one in particular-impulsive (reactive) aggression-appears to account for many facets of aggression-related dysfunction in psychiatric illness. Impulsive-aggression is significantly heritable, suggesting genetic transmission. However, the specific neurobiological mechanisms that mediate genetic risk for impulsive-aggression remain unclear. Here, we review extant data on the genetics and neurobiology of individual differences in impulsive-aggression, with particular attention to the role of genetic variation in Monoamine Oxidase A (MAOA) and its impact on serotonergic signaling within corticolimbic circuitry. PMID:24470068

  12. Exact impulsive gravitational waves in spacetimes of constant curvature

    CERN Document Server

    Podolsky, J

    2002-01-01

    Exact solutions exist which describe impulsive gravitational waves propagating in Minkowski, de Sitter, or anti-de Sitter universes. These may be either nonexpanding or expanding. Both cases in each background are reviewed here from a unified point of view. All the main methods for their construction are described systematically: the Penrose "cut and paste" method, explicit construction of continuous coordinates, distributional limits of sandwich waves, embedding from higher dimensions, and boosts of sources or limits of infinite accelerations. Attention is concentrated on the most interesting specific solutions. In particular, the nonexpanding impulsive waves that are generated by null multipole particles are described. These generalize the well-known Aichelburg-Sexl and Hotta-Tanaka monopole solutions. Also described are the expanding spherical impulses that are generated by snapping and colliding strings. Geodesics and some other properties of impulsive wave spacetimes are also summarized.

  13. Nucleus accumbens core and shell inactivation differentially affects impulsive behaviours in rats.

    Science.gov (United States)

    Feja, Malte; Hayn, Linda; Koch, Michael

    2014-10-01

    Impulsivity is a multifactorial phenomenon, determined by deficits in decision-making (impulsive choice) and impulse control (impulsive action). Recent findings indicate that impulsive behaviour is not only top-down controlled by cortical areas, but also modulated at subcortical level. The nucleus accumbens (NAc) might be a key substrate in cortico-limbic-striatal circuits involved in impulsive behaviour. Dissociable effects of the NAc subregions in various behavioural paradigms point to a potential functional distinction between NAc core and shell concerning different types of impulsivity. The present study used reversible inactivation of the rats' NAc core and shell via bilateral microinfusion of the GABAA receptor agonist muscimol (0.05?g/0.3?l) and fluorophore-conjugated muscimol (FCM, 0.27?g/0.3?l) in order to study their contribution to different aspects of impulse control in a 5-choice serial reaction time task (5-CSRTT) and impulsive choice in a delay-based decision-making T-maze task. Acute inactivation of NAc core as well as shell by muscimol increased impulsive choice, with higher impairments of the rats' waiting capacity in the T-maze following core injections compared to shell. Intra-NAc shell infusion of muscimol also induced specific impulse control deficits in the 5-CSRTT, while deactivation of the core caused severe general impairments in task performance. FCM did not affect animal behaviour. Our findings reveal clear involvement of NAc shell in both forms of impulsivity. Both subareas play a key role in the regulation of impulsive decision-making, but show functional dichotomy regarding impulse control with the core being more implicated in motivational and motor aspects. PMID:24810333

  14. DIMENSIONS OF IMPULSIVITY AMONG HEAVY DRINKERS, SMOKERS, AND HEAVY DRINKING SMOKERS: SINGULAR AND COMBINED EFFECTS

    OpenAIRE

    Moallem, Nathasha R.; Ray, Lara A

    2012-01-01

    Alcohol use and cigarette smoking commonly co-occur. The role impulsivity may play as a common underlying mechanism in alcohol use and cigarette smoking is of particular interest due to emerging evidence of it being a critical component across multiple forms of addiction. Impulsivity can be examined through several constructs including, risky decision-making, response inhibition, and delay reward discounting. Impulsivity and each of these specific constructs play significant roles in the init...

  15. 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.

  16. Formation of the compression zone in a plasma flow generated by a magnetoplasma compressor

    Energy Technology Data Exchange (ETDEWEB)

    Solyakov, D. G., E-mail: solyakov@ipp.kharkov.ua; Petrov, Yu. V.; Garkusha, I. E.; Chebotarev, V. V.; Ladygina, M. S.; Cherednichenko, T. N.; Morgal’, Ya. I.; Kulik, N. V.; Stal’tsov, V. V.; Eliseev, D. V. [National Academy of Sciences of Ukraine, Institute of Plasma Physics, National Science Center Kharkiv Institute of Physics and Technology (Ukraine)

    2013-12-15

    Processes occurring in a plasma flow generated by a magnetoplasma compressor (MPC) during the formation of the compression zone are discussed. The paper presents results of measurements of the spatial distribution of the electric current in the plasma flow, the temporal and spatial (along the flow) distributions of the plasma density, and the profiles of the velocity of individual flow layers along the system axis. The spatial distribution of the electromagnetic force in the flow is analyzed. It is shown that the plasma flow is decelerated when approaching the compression zone and reaccelerated after passing it. In this case, the plasma flow velocity decreases from ? = (2–3) × 10{sup 7} cm/s at the MPC output to ? < 10{sup 6} cm/s in the region of maximum compression and then again increases to 10{sup 7} cm/s at a distance of 15–17 cm from the MPC output. In some MPC operating modes, a displacement of the magnetic field from the compression zone and the formation of toroidal electric current vortices in the plasma flow after passing the compression zone were detected.

  17. 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.

  18. Whistler wave excitation by a loop antenna in a bounded collisional magnetoplasma

    Energy Technology Data Exchange (ETDEWEB)

    Kudrin, A V; Es' kin, V A [Department of Radiophysics, University of Nizhny Novgorod, 23 Gagarin Avenue, Nizhny Novgorod 603950 (Russian Federation); Krafft, C [Laboratoire de Physique et Technologie des Plasmas, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Zaboronkova, T M [Department of Applied Physics, Technical University of Nizhny Novgorod, 24 Minin Street, Nizhny Novgorod 603950 (Russian Federation)], E-mail: kud@rf.unn.ru

    2008-05-15

    Excitation of electromagnetic waves by spatially bounded given electric currents in the presence of an axially magnetized cylindrical plasma column surrounded by free space is studied. A rigorous solution for the total field comprising both the discrete and continuous parts of the spatial spectrum of the excited waves is found. Using the obtained field representation, an expression for the impedance of a loop antenna is derived and the contributions of guided and unguided modes of the column to the antenna impedance are determined for the whistler frequency range. Conditions have been revealed under which the real part of the antenna impedance is dominated by the contribution of guided waves. It is shown that when allowance for relatively small collisional losses in the plasma results in division of the guided whistler waves into weakly and strongly damped modes with significantly different field structures, appreciable redistribution of the antenna-launched power among the excited modes takes place. The results obtained are useful for clarification of the power-absorption mechanisms of whistler-range waves in a cylindrical magnetoplasma.

  19. 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

  20. 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

  1. Nonlinear ion-acoustic cnoidal waves in a dense relativistic degenerate magnetoplasma

    Science.gov (United States)

    El-Shamy, E. F.

    2015-03-01

    The complex pattern and propagation characteristics of nonlinear periodic ion-acoustic waves, namely, ion-acoustic cnoidal waves, in a dense relativistic degenerate magnetoplasma consisting of relativistic degenerate electrons and nondegenerate cold ions are investigated. By means of the reductive perturbation method and appropriate boundary conditions for nonlinear periodic waves, a nonlinear modified Korteweg-de Vries (KdV) equation is derived and its cnoidal wave is analyzed. The various solutions of nonlinear ion-acoustic cnoidal and solitary waves are presented numerically with the Sagdeev potential approach. The analytical solution and numerical simulation of nonlinear ion-acoustic cnoidal waves of the nonlinear modified KdV equation are studied. Clearly, it is found that the features (amplitude and width) of nonlinear ion-acoustic cnoidal waves are proportional to plasma number density, ion cyclotron frequency, and direction cosines. The numerical results are applied to high density astrophysical situations, such as in superdense white dwarfs. This research will be helpful in understanding the properties of compact astrophysical objects containing cold ions with relativistic degenerate electrons.

  2. Generalized magnetohydrodynamic equations for partially ionized dusty magnetoplasmas: Derivation and applications

    International Nuclear Information System (INIS)

    A comprehensive investigation of electromagnetic wave and instability phenomena in partially ionized, magnetized dusty plasmas has been carried out. By employing the multi-fluid balance equations along with the Maxwell equations, a compact set of coupled field equations for the cases in which the dust grains are either robust (vd=0) or dynamic is derived. These systems of partial differential equations are used to study wave phenomena and resistive tearing mode instabilities analytically as well as by means of numerical simulations. For robust dust grains, it is shown that coupled sound-Alfvacute en waves can appear even in the absence of ion-neutral collisions. The unstable tearing modes are coupled to convective drift modes, if the dust number density is inhomogeneous. In the induction equation two new source terms for self-generation of magnetic fields can be identified. In parameter regimes that are characterized by dynamic dust grains, the low-frequency phenomena develop on timescales that are governed by the dust particle inertia rather than the ion inertia, as it is the case in dust-free plasmas. The results of this investigation should be useful in understanding the properties of low-frequency electromagnetic wave phenomena and the formation of coherent structures in dusty magnetoplasmas whose main constituents are negatively charged dust grains, singly charged positive ions, and neutrals. copyright 1996 American Institute of Physics

  3. Solitons and shocks in dense astrophysical magnetoplasmas with relativistic degenerate electrons and positrons

    Energy Technology Data Exchange (ETDEWEB)

    Ali, S. [National Centre for Physics at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Ata-ur-Rahman [National Centre for Physics at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan)

    2014-04-15

    The linear and nonlinear properties of the ion-acoustic (IA) waves are investigated in a relativistically degenerate magnetoplasma, whose constituents are the electrons, positrons, and ions. The electrons and positrons are assumed to obey the Fermi-Dirac statistics, whereas the cold ions are taken to be inertial and magnetized. In linear analysis, various limiting cases are discussed both analytically and numerically. However, for nonlinear studies, the well-known reductive perturbation technique is employed to derive the Zakharov-Kuznetsov and Zakharov-Kuznetsov Burgers equations in the presence of relativistically degenerate electrons and positrons. Furthermore, with the use of hyperbolic tangent method, the equations are simplified to admit the soliton and shock wave solutions. Numerically, it is shown that the amplitude, width, and phase speed associated with the localized IA solitons and shocks are significantly influenced by the various intrinsic plasma parameters relevant to our model. The present analysis can be useful for understanding the collective processes in dense astrophysical environments like neutron stars, where the electrons and positrons are expected to be relativistic and degenerate.

  4. Dynamic behavior of the quantum Zakharov-Kuznetsov equations in dense quantum magnetoplasmas

    Science.gov (United States)

    Zhen, Hui-Ling; Tian, Bo; Wang, Yu-Feng; Zhong, Hui; Sun, Wen-Rong

    2014-01-01

    Quantum Zakharov-Kuznetsov (qZK) equation is found in a dense quantum magnetoplasma. Via the spectral analysis, we investigate the Hamiltonian and periodicity of the qZK equation. Using the Hirota method, we obtain the bilinear forms and N-soliton solutions. Asymptotic analysis on the two-soliton solutions shows that the soliton interaction is elastic. Figures are plotted to reveal the propagation characteristics and interaction between the two solitons. We find that the one soliton has a single peak and its amplitude is positively related to He, while the two solitons are parallel when He < 2, otherwise, the one soliton has two peaks and the two solitons interact with each other. Hereby, He is proportional to the ratio of the strength of magnetic field to the electronic Fermi temperature. External periodic force on the qZK equation yields the chaotic motions. Through some phase projections, the process from a sequence of the quasi-period doubling to chaos can be observed. The chaotic behavior is observed since the power spectra are calculated, and the quasi-period doubling states of perturbed qZK equation are given. The final chaotic state of the perturbed qZK is obtained.

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

    Energy Technology Data Exchange (ETDEWEB)

    Rahim, Z.; Qamar, A. [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan); National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Ali, S. [National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan)

    2014-07-15

    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.

  6. Dynamic behavior of the quantum Zakharov-Kuznetsov equations in dense quantum magnetoplasmas

    International Nuclear Information System (INIS)

    Quantum Zakharov-Kuznetsov (qZK) equation is found in a dense quantum magnetoplasma. Via the spectral analysis, we investigate the Hamiltonian and periodicity of the qZK equation. Using the Hirota method, we obtain the bilinear forms and N-soliton solutions. Asymptotic analysis on the two-soliton solutions shows that the soliton interaction is elastic. Figures are plotted to reveal the propagation characteristics and interaction between the two solitons. We find that the one soliton has a single peak and its amplitude is positively related to He, while the two solitons are parallel when He?e is proportional to the ratio of the strength of magnetic field to the electronic Fermi temperature. External periodic force on the qZK equation yields the chaotic motions. Through some phase projections, the process from a sequence of the quasi-period doubling to chaos can be observed. The chaotic behavior is observed since the power spectra are calculated, and the quasi-period doubling states of perturbed qZK equation are given. The final chaotic state of the perturbed qZK is obtained

  7. Dynamic behavior of the quantum Zakharov-Kuznetsov equations in dense quantum magnetoplasmas

    Energy Technology Data Exchange (ETDEWEB)

    Zhen, Hui-Ling; Tian, Bo, E-mail: tian-bupt@163.com; Wang, Yu-Feng; Zhong, Hui; Sun, Wen-Rong [State Key Laboratory of Information Photonics and Optical Communications, and School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China)

    2014-01-15

    Quantum Zakharov-Kuznetsov (qZK) equation is found in a dense quantum magnetoplasma. Via the spectral analysis, we investigate the Hamiltonian and periodicity of the qZK equation. Using the Hirota method, we obtain the bilinear forms and N-soliton solutions. Asymptotic analysis on the two-soliton solutions shows that the soliton interaction is elastic. Figures are plotted to reveal the propagation characteristics and interaction between the two solitons. We find that the one soliton has a single peak and its amplitude is positively related to H{sub e}, while the two solitons are parallel when H{sub e}?

  8. Impulsive Light-Like Signals

    Science.gov (United States)

    Barrabès, C.; Hogan, P. A.

    A general characterisation of an impulsive light-like signal was given1,2. The signal may consist of a shell of null matter and/or an impulsive gravitational wave. Both parts of the signal can be unambiguously identified3,4. The signals can be used to model bursts of gravitational radiation and light- like matter accompanying cataclysmic events such as supernovae and neutron star collisions. Also in high speed collisions of compact objects such as black-holes or neutron stars the gravitational fields of these objects resemble those of impulsive light-like signals when the objects are boosted to the speed of light. Several examples of impulsive light-like signals were presented, in particular those produced by recoil effects5 and by the Aichelburg-Sexl boost of an isolated gravitating multipole source6. The detection of these signals was also discussed7.

  9. 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.

  10. Periodic Motion of the van der Pol Equation with Impulsive Effect

    Science.gov (United States)

    Zheng, Shasha; Fu, Xilin

    In this paper, we investigate the dynamics of the periodic motion for switched van der Pol equation with impulsive effect, utilizing the theory of mapping dynamics in switching systems. For the optimized problem, we consider such impulsive dynamical model as switched system and analyze its features from a discontinuous point of view. Then, conceptions of switching sets as well as discrete mappings are briefly reviewed. By constructing generic mappings, we analyze the flow's periodic behaviors from the perspective of mapping structures. Finally, we apply our analysis and criterion to a specific impulsive model at fixed points and the periodic motions with impulse to the boundary are illustrated.

  11. The role of affective instability and UPPS impulsivity in borderline personality disorder features.

    Science.gov (United States)

    Tragesser, Sarah L; Robinson, R Joe

    2009-08-01

    Current theories of borderline personality disorder (BPD) suggest that extreme levels of affective instability/emotional dysregulation, impulsivity, or a combination of these traits account for the symptoms of BPD. The present study tested the extent to which personality measures of affective instability and impulsivity could account for BPD features in a nonclinical sample. One hundred forty-one undergraduates completed the Affective Lability Scale, the UPPS Impulsive Behavior Scale, and the Personality Assessment Inventory for Borderlines. Both affective instability and impulsivity were uniquely associated with BPD features. Shifts between euthymia and anger, and between anxiety and depression, were associated with BPD features, as were the urgency and (lack of) premeditation scales. Results indicated that specific BPD features may be differentially accounted for by affective instability vs. impulsivity, consistent with perspectives on BPD emphasizing combinations of affective instability and impulsivity as underlying dimensions of the disorder. PMID:19663657

  12. Impulsive Neural Networks Algorithm Based on the Artificial Genome Model

    Directory of Open Access Journals (Sweden)

    Yuan Gao

    2014-05-01

    Full Text Available To describe gene regulatory networks, this article takes the framework of the artificial genome model and proposes impulsive neural networks algorithm based on the artificial genome model. Firstly, the gene expression and the cell division tree are applied to generate spiking neurons with specific attributes, neural network structure, connection weights and specific learning rules of each neuron. Next, the gene segment duplications and divergence model are applied to design the evolutionary algorithm of impulsive neural networks at the level of the artificial genome. The dynamic changes of developmental gene regulatory networks are controlled during the whole evolutionary process. Finally, the behavior of collecting food for autonomous intelligent agent is simulated, which is driven by nerves. Experimental results demonstrate that the algorithm in this article has the evolutionary ability on large-scale impulsive neural networks

  13. 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

  14. Impulsivity: four ways five factors are not basic to addiction.

    Science.gov (United States)

    Gullo, Matthew J; Loxton, Natalie J; Dawe, Sharon

    2014-11-01

    Several impulsivity-related models have been applied to understanding the vulnerability to addiction. While there is a growing consensus that impulsivity is multifaceted, debate continues as to the precise number of facets and, more critically, which are most relevant to explaining the addiction-risk profile. In many ways, the current debate mirrors that which took place in the personality literature in the early 1990s (e.g., Eysenck's 'Big Three' versus Costa and McCrae's 'Big Five'). Indeed, many elements of this debate are relevant to the current discussion of the role of impulsivity in addictive behavior. Specifically, 1) the use of factor analysis as an atheoretical 'truth-grinding machine'; 2) whether additional facets add explanatory power over fewer; 3) the delineation of specific neurocognitive pathways from each facet to addictive behaviors, and; 4) the relative merit of 'top-down' versus 'bottom-up' approaches to the understanding of impulsivity. Ultimately, the utility of any model of impulsivity and addiction lies in its heuristic value and ability to integrate evidence from different levels of analysis. Here, we make the case that theoretically-driven, bottom-up models proposing two factors deliver the optimal balance of explanatory power, parsimony, and integration of evidence. PMID:24576666

  15. 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

  16. Formation of solitary structures in uniform and nonuniform magnetoplasmas with superthermal electrons: a non-reductive perturbative approach

    Science.gov (United States)

    Masood, W.; Hassan, Sunia; Batool, N.; Siddiq, M.

    2013-11-01

    Electrostatic solitary structures are studied in uniform and nonuniform magnetoplasmas with superthermal electrons. In the linear analysis, the differences in the acoustic frequencies for Maxwellian, Cairns, and Kappa distributed electrons for both homogeneous and inhomogeneous plasmas are highlighted and discussed. It is shown that using the linear dispersion relation, nonlinear Zakharov-Kuznetsov (ZK) equation can be derived both for the homogeneous and inhomogeneous magnetoplasmas. The solution of the ZK equation is presented using the tangent hyperbolic method. It is found that the increasing magnetic field and the angle of propagation enhances the amplitude whereas the increasing number density mitigates the amplitude of the acoustic drift solitary wave. Furthermore, it is observed that the amplitude of the solitary structure is maximum for Cairns, intermediate for Maxwellian, and minimum for the Kappa distributed electrons. The results presented in this paper may be beneficial to understand the formation of electrostatic drift solitary waves in planetary environments where the nonthermal population of electrons are observed by various satellite missions.

  17. 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 ?1 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 ?1 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.

  18. 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 ...

  19. High-intensity drying processes: Impulse drying. Progress report on furnish evaluations for impulse drying commercialization demonstration

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-02-01

    Laboratory and pilot scale experiments were performed to identify potential furnishes and operating parameters for upcoming high-speed pilot scale trials and commercial demonstration of impulse drying of heavy weight grades of paper. Results indicate that hydrodynamic specific surface is highly dependent on sheet formation and prehandling. Mill refined pulp and machine paper were comparable to laboratory prepared samples in regards to permeability and impulse drying. Process variables such as platen surface coating, felt type, felt moisture, and presteaming temperature profiles were investigated. Substantial improvements in sheet smoothness were achieved.

  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. 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.

  2. Impulsivity, Frontal Lobes and Risk for Addiction

    OpenAIRE

    Crews, Fulton Timm; Boettiger, Charlotte Ann

    2009-01-01

    Alcohol and substance abuse disorders involve continued use of substances despite negative consequences, i.e. loss of behavioral control of drug use. The frontal cortical areas of brain oversee behavioral control through executive functions. Executive functions include abstract thinking, motivation, planning, attention to tasks and inhibition of impulsive responses. Impulsiveness generally refers to premature, unduly risky, poorly conceived actions. Dysfunctional impulsivity includes deficits...

  3. 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.

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

    OpenAIRE

    Dell’Osso, 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-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, th...

  5. Impulsivity-like traits and risky driving behaviors among college students.

    Science.gov (United States)

    Pearson, Matthew R; Murphy, Elaine M; Doane, Ashley N

    2013-04-01

    The present study examined the predictive effects of five impulsivity-like traits (Premeditation, Perseverance, Sensation Seeking, Negative Urgency, and Positive Urgency) on driving outcomes (driving errors, driving lapses, driving violations, cell phone driving, traffic citations, and traffic collisions). With a convenience sample of 266 college student drivers, we found that each of the impulsivity-like traits was related to multiple risky driving outcomes. Positive Urgency (tendency to act impulsively when experiencing negative affect) was the most robust predictor of risky driving outcomes. Positive Urgency is a relatively newly conceptualized impulsivity-like trait that was not examined in the driving literature previously, suggesting a strong need to further examine its role as a personality trait related to risky driving. These findings generally support the multidimensional assessment of impulsivity-like traits, and they specifically support the addition of Positive Urgency to a list of risk factors for risky driving behaviors. PMID:23428428

  6. 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.

  7. 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)

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

    Science.gov (United States)

    Javan, N. Sepehri; Homami, S. H. H.

    2015-02-01

    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.

  9. 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)

  10. Effects of sleep deprivation on impulsive behaviors in men and women.

    Science.gov (United States)

    Acheson, Ashley; Richards, Jerry B; de Wit, Harriet

    2007-08-15

    The purpose of this study was to examine the effects of sleep deprivation on impulsive behavior. Patients with impulse control disorders often report sleep problems, and sleep deprivation even in healthy individuals impairs cognition, decision-making, and perhaps impulse control. To characterize the effects of sleep loss on specific forms of impulsive behavior, we tested the effects of overnight, monitored sleep deprivation on measures of impulsivity and cognition in healthy volunteers. Ten men and ten women completed two 24 h sessions in random order, in which they were either allowed to sleep normally or remained awake all night. At 8:30 am and 6:15 pm on the day after sleep or no sleep, participants were tested on the Balloon Analogue Risk Task (BART), the Experiential Discounting Task, the Adjusting Amount Delay and Probability Discounting Task, and the Stop Task. Participants also completed mood questionnaires and the Automated Neuropsychological Assessment Matrix (ANAM) throughout the course of the day. Sleep deprivation did not affect most of the measures of impulsive behavior. However, on the BART, sleep deprivation decreased risk taking in women, but not men. Sleep deprivation produced expected increases in subjective fatigue, and impaired performance on measures of attention and cognitive efficiency on the ANAM. The results indicate that sleep deprivation does not specifically increase impulsive behaviors but may differentially affect risk taking in men and women. PMID:17477941

  11. The role of neural impulse control mechanisms for dietary success in obesity.

    Science.gov (United States)

    Weygandt, Martin; Mai, Knut; Dommes, Esther; Leupelt, Verena; Hackmack, Kerstin; Kahnt, Thorsten; Rothemund, Yvonne; Spranger, Joachim; Haynes, John-Dylan

    2013-12-01

    Deficits in impulse control are discussed as key mechanisms for major worldwide health problems such as drug addiction and obesity. For example, obese subjects have difficulty controlling their impulses to overeat when faced with food items. Here, we investigated the role of neural impulse control mechanisms for dietary success in middle-aged obese subjects. Specifically, we used a food-specific delayed gratification paradigm and functional magnetic resonance imaging to measure eating-related impulse-control in middle-aged obese subjects just before they underwent a twelve-week low calorie diet. As expected, we found that subjects with higher behavioral impulse control subsequently lost more weight. Furthermore, brain activity before the diet in VMPFC and DLPFC correlates with subsequent weight loss. Additionally, a connectivity analysis revealed that stronger functional connectivity between these regions is associated with better dietary success and impulse control. Thus, the degree to which subjects can control their eating impulses might depend on the interplay between control regions (DLPFC) and regions signaling the reward of food (VMPFC). This could potentially constitute a general mechanism that also extends to other disorders such as drug addiction or alcohol abuse. PMID:23867558

  12. Prueba de impulso cefálico / Head impulse test

    Scientific Electronic Library Online (English)

    Hayo A, Breinbauer K; José Luis, Anabalón B.

    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. Abstract in english 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.

  13. Impulsivity, gambling cognitions, and the gambler's fallacy in university students.

    Science.gov (United States)

    Marmurek, Harvey H C; Switzer, Jessica; D'Alvise, Joshua

    2015-03-01

    The present study explored the associations among impulsivity, gambling cognitions, and behavioral adherence to the gambler's fallacy in university students (N = 142). Both impulsivity and gambling cognitions were significant predictors of non-problem and problem gambler categories as defined the Problem Gambling Severity Index. A logistic regression analysis showed that the independent contribution of cognition was statistically significant but that the contribution of impulsivity was not. A behavioral measure of gambling was obtained by asking participants to play an online game of roulette for a maximum of 15 min. Only outside bets were permitted whereby participants were to bet on the color of the winning number. Adherence to the gambler's fallacy was indexed by the likelihood of betting on an alternation in the color of the winning number as the number of consecutive outcomes of the other color increased. Gambling cognitions and gender, but not impulsivity, were associated with adherence to the gambler's fallacy. Tracing the sources of specific influences on gambling behavior may benefit from a framework that distinguishes between "hot" (emotional) and "cold" (non-emotional) mechanisms that promote problem gambling. PMID:24293013

  14. Differential associations between obesity and behavioral measures of impulsivity.

    Science.gov (United States)

    Lawyer, Steven R; Boomhower, Steven R; Rasmussen, Erin B

    2015-12-01

    A growing literature indicates that impulsivity is a fundamental behavioral process that underlies obesity. However, impulsivity is a multidimensional construct, which comprises independent patterns of decision-making that could be uniquely associated with obesity. No research to date has clarified whether obesity is differentially associated with specific behavioral aspects of impulsivity. This study examined whether obesity was differentially associated with patterns of decision-making associated with impulsivity-delay discounting, probability discounting, and response inhibition. Young adults (n = 296; 44.3% male) age 18-30 were recruited from the community with media advertisements. Participants completed a series of standard self-report measures of health outcomes and behavioral measures of delay discounting, probability discounting, and response inhibition individually in a laboratory. Associations between body mass index (BMI) and behavioral outcomes in the whole sample indicated that BMI was associated with age, delay discounting, and probability discounting, but not response inhibition. A logistic regression that included age, sex, and substance use as covariates found that delay discounting, but neither probability discounting nor response inhibition, was associated with obesity status. Sensitivity to delay, rather than response inhibition and sensitivity to uncertainty, may be the best correlate of obesity status in adults. These findings are relevant to our understanding of the fundamental behavioral processes associated with obesity. PMID:26235925

  15. Impulse control maximum principle: Theory and applications

    OpenAIRE

    Chahim, M.

    2013-01-01

    The contribution of this paper is threefold. First, this thesis extends the existing theory on Impulse Control by deriving the necessary optimality conditions in current value formulation and provide a transformation such that the Impulse Control Maximum Principle can be applied to problems having a fixed cost. Moreover, this thesis points out that meaningful problems do not satisfy the sufficiency conditions. Second, in this thesis the Impulse Control Maximum Principle is applied to dike hei...

  16. 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...

  17. On a SIS model with impulsive effects

    OpenAIRE

    De la sen, M.; A. Ibeas; S. Alonso-Quesada

    2011-01-01

    This paper is concerned with a SIS (susceptible, infected and susceptible populations) propagation disease model with a nonlinear incidence rate and eventual impulsive (non- necessarily being simultaneous) culling of both populations. The disease transmission does not necessarily take into account the total population as a normalizing effect. In this sense, the considered model is a mixed pseudo-mass. The positivity, stability of both the impulse- free and impulsive under pu...

  18. 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

  19. Impulsiveness without discounting: the ecological rationality hypothesis.

    OpenAIRE

    Stephens, David W.; Kerr, Benjamin; Fernández-Juricic, Esteban

    2004-01-01

    Observed animal impulsiveness challenges ideas from foraging theory about the fitness value of food rewards, and may play a role in important behavioural phenomena such as cooperation and addiction. Behavioural ecologists usually invoke temporal discounting to explain the evolution of animal impulsiveness. According to the discounting hypothesis, delay reduces the fitness value of the delayed food. We develop an alternative model for the evolution of impulsiveness that does not require discou...

  20. Impulse response matching estimators for DSGE models

    OpenAIRE

    Guerron-Quintana, Pablo; Inoue, Atsushi; Kilian, Lutz

    2014-01-01

    One of the leading methods of estimating the structural parameters of DSGE mod- els is the VAR-based impulse response matching estimator. The existing asympotic theory for this estimator does not cover situations in which the number of impulse response parameters exceeds the number of VAR model parameters. Situations in which this order condition is violated arise routinely in applied work. We establish the consistency of the impulse response matching estimator in this situation, we derive it...

  1. 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

  2. Impulse in a Double Ball Bounce

    Directory of Open Access Journals (Sweden)

    Daniel Y. Nielsen

    2010-06-01

    Full Text Available A steel ball was dropped onto a handball which was resting on top of a horizontal Vernier force-plate. The relationship between the impact momentum of the steel ball and the impulse on the force-plate was investigated. The measured impulse was found to be proportional to the impact momentum of the falling ball, with the impulse being 2.3 times greater than the momentum. The impact of the metal ball caused the handball to compress and then bounce up following the steel ball’s bounce. This contributed to the measured impulse being greater than twice the impact momentum.

  3. Saturation of Richtmyer's impulsive model

    International Nuclear Information System (INIS)

    In this Brief Communication, we use results from two-dimensional simulations to calculate for what product of perturbation wave number (k) and initial amplitude (a0) the Richtmyer impulsive model will fail in its prediction of shock wave driven instability growth as a function of initial shock Mach number. For ''large'' ka0, we suggest a formula which bounds the maximum value of the ratio of the amplitude growth rate over the interface speed by one minus the ratio of the interface speed and the transmitted shock speed. (c) 2000 American Institute of Physics

  4. 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…

  5. Acoustic Radiation Force Impulse Imaging for Differentiation of Thyroid Nodules

    OpenAIRE

    Bojunga, Joerg; Dauth, Nina; Berner, Christian; Meyer, Gesine; Holzer, Katharina; Voelkl, Lisa; Herrmann, Eva; Schroeter, Hartmut; Zeuzem, Stefan; Friedrich-Rust, Mireen

    2012-01-01

    Background: Acoustic Radiation Force Impulse (ARFI)-imaging is an ultrasound-based elastography method enabling quantitative measurement of tissue stiffness. The aim of the present study was to evaluate sensitivity and specificity of ARFI-imaging for differentiation of thyroid nodules and to compare it to the well evaluated qualitative real-time elastography (RTE). Methods: ARFI-imaging involves the mechanical excitation of tissue using acoustic pulses to generate localized displacements ...

  6. 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.

  7. A Thrust and Impulse Study of Guanidinium Azo-Tetrazolate as an Additive for Hybrid Rocket Fuel

    Science.gov (United States)

    Patton, J.; Wright, A. M.; Dunn, L.; Alford, B.

    2000-03-01

    A thrust and impulse study of the hybrid rocket fuel additive Guanidinium Azo-Tetrazolate (GAT) was conducted at the University of Arkansas at Little Rock (UALR) Hybrid Rocket Facility. GAT is an organic salt with a high percentage of nitrogen. GAT was mixed with the standard hybrid rocket fuel, Hydroxyl-Terminated Polybutadiene (HTPB), in the concentration of 15%, by mass. The fuel grains with the GAT additive were fired for 4 second runs with the oxygen flows of 0.05, 0.07, 0.09, and 0.12 lbm/sec. For each run average thrust, total impulse, and specific impulse were measured. Average thrust, specific impulse, and total impulse vs. oxygen flow were plotted. Similar data was collected for plain HTPB/PAPI fuels for comparison. GAT was found to increase the thrust output when it was added to the standard hybrid rocket fuel, HTPB. GAT also increased the total impulse during the run. The thrust and total impulse were increased at all flows, but especially at the lower oxygen flow rates. Specific impulse only increased during the lower oxygen flow runs, and decreased slightly for the higher oxygen flow runs.

  8. Overlapping and disease specific aspects of impulsivety in children and adolescents with schiozphrenia 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

    2014-01-01

    Background and aim: Dimensions of impulsivity have been observed in Attention-Deficit/Hyperactivity Disorder (ADHD) and schizophrenia patients. The purpose is to identify disease specific and overlapping aspects of impulsivity in children and adolescents with ADHD or early-onset schizophrenia spectrum disorders. Materials and plan: Motor impulsivity (Stop Signal Task), reflection impulsivity (Information Sampling Task), and trait impulsivity (Barratt Impulsiveness Scale) are compared between thr...

  9. Temporal Preparation, Response Inhibition and Impulsivity

    Science.gov (United States)

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

    2010-01-01

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

  10. On Some New Impulsive Integral Inequalities

    OpenAIRE

    Jianli Li

    2008-01-01

    We establish some new impulsive integral inequalities related to certain integral inequalities arising in the theory of differential equalities. The inequalities obtained here can be used as handy tools in the theory of some classes of impulsive differential and integral equations.

  11. 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…

  12. Robust dissipativity for uncertain impulsive dynamical systems

    Directory of Open Access Journals (Sweden)

    Liu Bin

    2003-01-01

    Full Text Available We discuss the robust dissipativity with respect to the quadratic supply rate for uncertain impulsive dynamical systems. By employing the Hamilton-Jacobi inequality approach, some sufficient conditions of robust dissipativity for this kind of system are established. Finally, we specialize the obtained results to the case of uncertain linear impulsive dynamical systems.

  13. Robust dissipativity for uncertain impulsive dynamical systems

    OpenAIRE

    Liu Bin; Liu Xinzhi; Liao Xiaoxin

    2003-01-01

    We discuss the robust dissipativity with respect to the quadratic supply rate for uncertain impulsive dynamical systems. By employing the Hamilton-Jacobi inequality approach, some sufficient conditions of robust dissipativity for this kind of system are established. Finally, we specialize the obtained results to the case of uncertain linear impulsive dynamical systems.

  14. Successful restrained eating and trait impulsiveness.

    Science.gov (United States)

    van Koningsbruggen, Guido M; Stroebe, Wolfgang; Aarts, Henk

    2013-01-01

    Restrained eaters with high scores on the Perceived Self-Regulatory Success in Dieting Scale (PSRS) are more successful than low scorers in regulating their food intake. According to the theory of temptation-elicited goal activation (Fishbach, Friedman, & Kruglanski, 2003), they have become successful because, due to earlier repeated instances of successful self-control, they formed an associative link between temptations and thoughts of dieting. It is unclear, however, why they should have been more successful in earlier attempts at self-control than their unsuccessful counterparts. We examined whether trait impulsiveness plays a role by investigating the associations between dietary restraint, trait impulsiveness, and PSRS. Results showed that the interaction between dietary restraint and impulsiveness predicted dieting success: A lower level of impulsiveness was associated with greater dieting success among restrained eaters. These results suggest that restrained eaters who are less impulsive are more likely to become successful restrained eaters as identified with the PSRS. PMID:23017465

  15. 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 ps<0.05). Future research is needed to confirm precursors to eating episodes in food addiction, elucidate causal mechanisms, and support an explanatory model of food addiction. PMID:26164390

  16. Inductance and near fields of a loop antenna in a cold magnetoplasma in the whistler frequency band

    Science.gov (United States)

    Gushchin, M. E.; Zaboronkova, T. M.; Krafft, C.; Korobkov, S. V.; Kostrov, A. V.

    2012-09-01

    The influence of a magnetoplasma on the inductance of a circular loop antenna oriented perpendicular to the ambient static magnetic field and operated in the whistler frequency band is studied. Based on a strict electrodynamic approach, the analytical treatment of the antenna reactance is performed for a uniform rf current distribution along the antenna wire. Calculations are made for plasma parameters and operating frequencies typical for active ionospheric experiments and laboratory rf (helicon) sources of dense magnetized plasmas. It is shown that the plasma influence on the inductance of the loop antenna remains relatively weak, even for antennas with dimensions close to half of the longitudinal whistler wavelength, when the rf field distribution in the antenna near zone is strongly different from that in vacuum. The theoretical predictions are confirmed by measurements performed on the large KROT plasma device. The results obtained are of crucial importance for the preparation of active ionospheric experiments and for the matching of loop antennas used in laboratory rf sources of dense magnetized plasmas.

  17. Inductance and near fields of a loop antenna in a cold magnetoplasma in the whistler frequency band

    Energy Technology Data Exchange (ETDEWEB)

    Gushchin, M. E.; Korobkov, S. V.; Kostrov, A. V. [Institute of Applied Physics, 603950 Nizhny Novgorod (Russian Federation); Zaboronkova, T. M. [Department of Applied Physics, Technical University of Nizhny Novgorod, 603950 Nizhny Novgorod (Russian Federation); Krafft, C. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, 91128 Palaiseau Cedex, Univ. Paris Sud, 91405 Orsay Cedex (France)

    2012-09-15

    The influence of a magnetoplasma on the inductance of a circular loop antenna oriented perpendicular to the ambient static magnetic field and operated in the whistler frequency band is studied. Based on a strict electrodynamic approach, the analytical treatment of the antenna reactance is performed for a uniform rf current distribution along the antenna wire. Calculations are made for plasma parameters and operating frequencies typical for active ionospheric experiments and laboratory rf (helicon) sources of dense magnetized plasmas. It is shown that the plasma influence on the inductance of the loop antenna remains relatively weak, even for antennas with dimensions close to half of the longitudinal whistler wavelength, when the rf field distribution in the antenna near zone is strongly different from that in vacuum. The theoretical predictions are confirmed by measurements performed on the large KROT plasma device. The results obtained are of crucial importance for the preparation of active ionospheric experiments and for the matching of loop antennas used in laboratory rf sources of dense magnetized plasmas.

  18. 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)

  19. Modified Zakharov-Kuznetsov equation for a non-uniform electron-positron-ion magnetoplasma with kappa-distributed electrons

    Science.gov (United States)

    Ahmad, Ali; Masood, W.

    2015-10-01

    > We investigate the low-frequency (by comparison with the ion Larmor frequency) electrostatic solitary structures in a spatially non-uniform electron-positron-ion (e-p-i) magnetoplasma with non-Maxwellian electrons. A linear dispersion relation for the obliquely propagating ion acoustic drift wave is derived and it is shown that the non-Maxwellian electron population modifies the dispersion characteristics of the wave under consideration. We also carry out a nonlinear analysis and derive the modified Zakharov-Kuznetsov (MZK) equation for the coupled drift acoustic wave in a non-uniform magnetized plasma. We highlight the differences between the MZK equation and its homogeneous counterpart. We also find the solution of the MZK equation using the tangent hyperbolic method. It is observed that the electron spectral index , positron concentration, and propagation angle alter the structure of the ion acoustic drift solitary waves. The results obtained in this paper may be beneficial to understanding the propagation characteristics of electrostatic drift solitary structures in the interstellar medium and in laboratory experiments where electron-positron plasmas have recently been created by impinging ultra-intense laser pulses on a solid density target at the Lawrence Livermore National Laboratory (LLNL).

  20. Impulse in a Double Ball Bounce

    OpenAIRE

    Daniel Y. Nielsen

    2010-01-01

    A steel ball was dropped onto a handball which was resting on top of a horizontal Vernier force-plate. The relationship between the impact momentum of the steel ball and the impulse on the force-plate was investigated. The measured impulse was found to be proportional to the impact momentum of the falling ball, with the impulse being 2.3 times greater than the momentum. The impact of the metal ball caused the handball to compress and then bounce up following the steel ball’s bounce. This cont...

  1. The relationship of momentary anger and impulsivity to bulimic behavior.

    Science.gov (United States)

    Engel, Scott G; Boseck, Justin J; Crosby, Ross D; Wonderlich, Stephen A; Mitchell, James E; Smyth, Joshua; Miltenberger, Raymond; Steiger, Howard

    2007-03-01

    Past research has suggested that negative affect may be a causal factor for eating disordered behaviors. More specifically, research has shown that anger appears to be one aspect of negative affect that is particularly relevant in bulimic patients. Previous studies have also shown that the relationship between negative affect and eating disordered behaviors may partially depend upon personality variables such as impulsivity. The present study examined whether the relationship between anger and eating disordered behaviors is moderated by impulsivity. Subjects completed an ecological momentary assessment (EMA) protocol for an average of 2 weeks. Findings revealed that overall antecedent anger level and the variability of antecedent anger predicted binge-eating episodes and that these relationships were moderated by participants' level of impulsivity. These findings suggest that personality variables impact the way that anger and eating behaviors relate. They also suggest that the variability of antecedent anger may be a fruitful avenue for future research for those interested in causal variables associated with bulimia nervosa. PMID:16697350

  2. Stability analysis of impulsive parabolic complex networks

    International Nuclear Information System (INIS)

    Highlights: ? Two impulsive parabolic complex network models are proposed. ? The global exponential stability of impulsive parabolic complex networks are considered. ? The robust global exponential stability of impulsive parabolic complex networks are considered. - Abstract: In the present paper, two kinds of impulsive parabolic complex networks (IPCNs) are considered. In the first one, all nodes have the same time-varying delay. In the second one, different nodes have different time-varying delays. Using the Lyapunov functional method combined with the inequality techniques, some global exponential stability criteria are derived for the IPCNs. Furthermore, several robust global exponential stability conditions are proposed to take uncertainties in the parameters of the IPCNs into account. Finally, numerical simulations are presented to illustrate the effectiveness of the results obtained here.

  3. Active noise cancellation algorithms for impulsive noise.

    Science.gov (United States)

    Li, Peng; Yu, Xun

    2013-04-01

    Impulsive noise is an important challenge for the practical implementation of active noise control (ANC) systems. The advantages and disadvantages of popular filtered-X least mean square (FXLMS) ANC algorithm and nonlinear filtered-X least mean M-estimate (FXLMM) algorithm are discussed in this paper. A new modified FXLMM algorithm is also proposed to achieve better performance in controlling impulsive noise. Computer simulations and experiments are carried out for all three algorithms and the results are presented and analyzed. The results show that the FXLMM and modified FXLMM algorithms are more robust in suppressing the adverse effect of sudden large amplitude impulses than FXLMS algorithm, and in particular, the proposed modified FXLMM algorithm can achieve better stability without sacrificing the performance of residual noise when encountering impulses. PMID:24363493

  4. 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.

  5. Impulsively generated fast coronal pulsations

    International Nuclear Information System (INIS)

    Rapid oscillations in the corona are discussed from a theoretical standpoint, developing some previous work on ducted, fast magnetoacoustic waves in an inhomogeneous medium. In the theory, impulsively (e.g., flare) generated mhd (magnetohydrodynamic) waves are ducted by regions of low Alfven speed (high density) such as coronal loops. Wave propagation in such ducts is strongly dispersive and closely akin to the behavior of Love waves in seismology, Pekeris waves in oceanography and guided waves in fiber optics. Such flare-generated magnetoacoustic waves possess distinctive temporal signatures consisting of periodic, quasi-periodic and decay phases. The quasi-periodic phase possesses the strongest amplitudes and the shortest time scales. Time scales are typically of the order of a second for inhomogeneities (coronal loop width) of 1000 km and Alfven speeds of 1000/kms, and pulse duration times are of tens of seconds. Quasi-periodic signatures have been observed in radio wavelengths for over a decade and more recently by SMM. It is hoped that the theoretical ideas outlined may be successfully related to these observations and thus aid the interpretation of oscillatory signatures recorded by SMM. Such signatures may also provide a diagnostic of coronal conditions. New aspects of the ducted mhd waves, for example their behavior in smoothly varying as opposed to tube-like inhomogeneities, are currently under investigation. The theory is not restricted to loops but applied equally to open field regions

  6. Anger and Impulsivity in Adolescents Attempting Suicide

    OpenAIRE

    AKIN, Elif; Meral BERKEM

    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...

  7. Arbitration between controlled and impulsive choices

    OpenAIRE

    Economides, M.; Guitart-Masip, M; Kurth-Nelson, Z.; DOLAN, R. J.

    2015-01-01

    The impulse to act for immediate reward often conflicts with more deliberate evaluations that support long-term benefit. The neural architecture that negotiates this conflict remains unclear. One account proposes a single neural circuit that evaluates both immediate and delayed outcomes, while another outlines separate impulsive and patient systems that compete for behavioral control. Here we designed a task in which a complex payout structure divorces the immediate value of acting from the o...

  8. 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

  9. Active noise cancellation algorithms for impulsive noise

    OpenAIRE

    Li, Peng; Yu, Xun

    2012-01-01

    Impulsive noise is an important challenge for the practical implementation of active noise control (ANC) systems. The advantages and disadvantages of popular filtered-X least mean square (FXLMS) ANC algorithm and nonlinear filtered-X least mean M-estimate (FXLMM) algorithm are discussed in this paper. A new modified FXLMM algorithm is also proposed to achieve better performance in controlling impulsive noise. Computer simulations and experiments are carried out for all three algorithms and th...

  10. BDNF concentration and impulsiveness level in post-traumatic stress disorder.

    Science.gov (United States)

    Martinotti, Giovanni; Sepede, Gianna; Brunetti, Marcella; Ricci, Valerio; Gambi, Francesco; Chillemi, Eleonora; Vellante, Federica; Signorelli, Maria; Pettorruso, Mauro; De Risio, Luisa; Aguglia, Eugenio; Angelucci, Francesco; Caltagirone, Carlo; Di Giannantonio, Massimo

    2015-10-30

    Among the symptoms of post-traumatic stress disorder (PTSD), impulsiveness has been observed in patients with high levels of hyperarousal. Recent literature reveals the importance of investigating the role of neurotrophins, such as brain-derived neurotrophic factor (BDNF), in several psychiatric disorders. Specifically, contrasting findings have been reported on the levels of serum BDNF in subjects with PTSD. The aim of the present study was to investigate the correlation between BDNF serum levels and impulsiveness in PTSD. To this end, we measured BDNF serum levels in 23 PTSD patients and a control group of 19 trauma-exposed non-PTSD subjects. Results indicate a positive correlation in the PTSD group; that is, the higher the BDNF levels the higher the impulsiveness score, as measured by the Barratt Impulsiveness Scale (BIS-11), suggesting that impulsiveness could be associated with greater BDNF production. Alternatively, it is also possible that high impulsiveness acts as a psychological mechanism that counteracts the negative effects exerted by the traumatic experience and the associated obsessive thoughts. The present paper discusses both hypotheses. PMID:26277035

  11. Approbation of the Russian-language version of the Barratt Impulsiveness Scale (BIS-11

    Directory of Open Access Journals (Sweden)

    Enikolopov S. N.

    2015-11-01

    Full Text Available The results of approbation of the Russian-language version of the questionnaire measure of impulsivity "Scale of the Barratt Impulsivity" (BIS-11. Demonstrated reliability and validity obtained the Russian version of the questionnaire. The study involved 200 people (among them 50 patients of the hospital. Assessment of validity was conducted by comparing the results with the results of the following methods: questionnaire of the I7 – Impulsiveness, (7-I version. A. Eysenck, S. Eysenck. Adaptation of the T. V. Kornilova, A. A. Dolnikova, 16 LF (Cattell. Correlation analysis of the scale of the Questionnaire with specific scales overall personality Questionnaire 16 PF and Kettell special I7 Impulsiveness Questionnaire Eysenck showed that the construct validity of the Questionnaire BIS-11 overall confirmed. It is shown that people with personality disorders (mainly psychopathy, Impulsivity Scale the Barratt have the level of impulsivity is significantly higher than the group norms. The results of the study allow to recommend the Russian version of the questionnaire BIS-11 for use in clinical diagnostics, in the field of training and education to determine proficiency.

  12. The effects of depression and impulsivity on obesity and binge eating disorder

    Directory of Open Access Journals (Sweden)

    bilge burcak annagur

    2015-01-01

    Full Text Available Objective: The aim of study was to evaluate depression and impulsivity in obese people with binge eating disorder (BED. Method: The study included 149 obese study participants who were compared to 151 non-obese healthy controls. They were assessed with the Structured Clinical Interview (SCID-I, Eating Attitudes Test (EAT, Beck Depression Inventory (BDI, and Barratt Impulsiveness Scale-11 (BIS-11. Results: The prevalence of BED was 47.6% in the obese study participants. Obesity with BED was more common in female participants. Depressive disorder was detected in 41.2% of the obese subjects. There was no significant difference between BED (+ and BED (- groups with respect to depressive disorder (p>0.05. The cognitive impulsivity and non-planning activity scores of the depressive group were significantly higher than for the participants without depression (p<0.05. The cognitive impulsivity scores of depressive obese participants were significantly higher than for obese participants without depression (p<0.05. Conclusion: Obesity appears to be associated with depression rather than impulsivity. Impulsivity was found in obese people with binge-eating specifically. This study suggests that depression and/or binge eating may be mediating factors for the outcome of obesity.

  13. 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

  14. 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

  15. Integral manifolds for uncertain impulsive differential–difference equations with variable impulsive perturbations

    International Nuclear Information System (INIS)

    In the present paper sufficient conditions for the existence of integral manifolds of uncertain impulsive differential–difference equations with variable impulsive perturbations are obtained. The investigations are carried out by means the concepts of uniformly positive definite matrix functions, Hamilton–Jacobi–Riccati inequalities and piecewise continuous Lyapunov’s functions

  16. 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

  17. [Impulsivity and compulsivity in cocaine dependent individuals].

    Science.gov (United States)

    Fernández-Serrano, María José; Cesar Peraleslópez, José; Moreno-López, Laura; Santos-Ruiz, Ana; Pérez-García, Miguel; Verdejogarcía, Antonio

    2012-01-01

    A recent theoretical approach describes addiction as a dynamic behavioural change process on the impulsivity-compulsivity axis. However, on the basis of current evidence, it is still difficult to establish a selective association between the course of addiction and individual transition along this axis. The aim of this study is to categorize each of the individuals in a sample of cocaine-dependent patients (CDI) as mainly impulsive or mainly compulsive, on the basis of their performance in neuropsychological inhibition and perseveration tests, and to test the association between the assigned category and their scores in trait impulsivity, and severity of cocaine addiction (measured by means of self-report assessment tools). A total of 42 CDI and 65 healthy control individuals (HCI) were assessed using the UPPS-P Scale (to explore trait impulsivity), the Stroop and Go/No Go (to assess response inhibition), and Revised-Strategy Application and Probabilistic Reversal tests (to assess response perseveration). Forty-five per cent of the CDIs were classified as compulsive, and this subgroup scored significantly higher than the impulsive group on the UPPS-P dimensions of lack of perseverance and lack of premeditation. A substantial proportion of CDIs can be classified as compulsive. No differences between compulsive and impulsive CDIs were found with regard to severity of exposure to cocaine; however, patients classified as compulsive by means of neuropsychological tasks are less perseverative in the pursuit of long-term objectives and more prone to make under-meditated decisions, as shown by trait impulsivity assessment questionnaires. PMID:22648313

  18. 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

  19. 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...

  20. Impulsive choice behavior in four strains of rats: Evaluation of possible models of Attention Deficit/Hyperactivity Disorder

    OpenAIRE

    Garcia, Ana; Kirkpatrick, Kimberly

    2012-01-01

    Several studies have examined impulsive choice behavior in spontaneously hypertensive rats (SHRs) as a possible pre-clinical model for Attention-Deficit/Hyperactivity Disorder (ADHD). However, this strain was not specifically selected for the traits of ADHD and as a result their appropriateness as a model has been questioned. The present study investigated whether SHRs would exhibit impulsive behavior in comparison to their control strain, Wistar Kyoto (WKY) rats. In addition, we evaluated a ...

  1. Video Game Therapy for Emotional Regulation and Impulsivity Control in a Series of Treated Cases with Bulimia Nervosa

    OpenAIRE

    Konstantas, Dimitri; Ben Moussa, Maher; Fagundo, Ana Beatriz; Santamaría, Juan José; Forcano, Laura; Giner-Bartolomé, Cristina; Jiménez-Murcia, Susana; Sánchez, Isabel; Granero, Roser; Magnenat-Thalmann, Nadia; Lam, Tony; Lucas, Mikkel; Nielsen, Jeppe; Bults, Richard; Tarrega, Salomé

    2013-01-01

    Although standard psychological treatments have been successful in treating several core features in eating disorders (ED), other characteristics such as emotional regulation or impulsivity appear to be more resistant to change. There is a growing body of evidence to support the efficacy of cognitive remediation for cognitive and emotional difficulties in ED. Playmancer/ Islands is a video game (VG) designed to specifically treat mental disorders, characterized by problems in impulse control....

  2. Underground scanning with an impulse radar

    International Nuclear Information System (INIS)

    Impulse radar is being evaluated for possible applications at the Waste Isolation Pilot Project (WIPP) in southeastern New Mexico. Potential applications are (1) scanning salt to identify inclusions, structural discontinuities, and other anomalies before excavation; and (2) verifying the locations of stored radioactive-waste canisters. Four underground experiments were run. The extent and shape of dome-salt pillars and a langbeinite pillar were measured with the radar. Metal targets that simulated waste canisters were located to within a few centimetres after they had been buried for 18 months. If the material being scanned contains clay seams and other conductive inclusions, penetration by radar is limited. It is anticipated that clean bedded salt will be an excellent medium for scanning with an impulse radar. The impulse radar as it now exists can be used for WIPP applications

  3. Almost periodic solutions of impulsive differential equations

    CERN Document Server

    Stamov, Gani T

    2012-01-01

    Impulsive differential equations are suitable for the mathematical simulation of evolutionary processes in which the parameters undergo relatively long periods of smooth variation followed by short-term rapid changes (that is, jumps) in their values. Processes of this type are often investigated in various fields of science and technology. The question of the existence and uniqueness of almost periodic solutions of differential equations is an age-old problem of great importance. The qualitative theory of impulsive differential equations is currently undergoing rapid development in relation to the investigation of various processes which are subject to impacts during their evolution, and many findings on the existence and uniqueness of almost periodic solutions of these equations are being made. This book systematically presents findings related to almost periodic solutions of impulsive differential equations and illustrates their potential applications.

  4. Impulsivity and Aggression in Female BPD and ADHD Patients: Association with ACC Glutamate and GABA Concentrations.

    Science.gov (United States)

    Ende, Gabriele; Cackowski, Sylvia; Van Eijk, Julia; Sack, Markus; Demirakca, Traute; Kleindienst, Nikolaus; Bohus, Martin; Sobanski, Esther; Krause-Utz, Annegret; Schmahl, Christian

    2016-01-01

    Borderline personality disorder (BPD) and attention-deficit-hyperactivity disorder (ADHD) are both characterized by high impulsivity and difficulties in controlling anger and aggression. In BPD, comorbid ADHD may further increase impulsivity. For both disorders, altered MR spectroscopy levels of the neurotransmitters glutamate and GABA as well as some correlations with impulsivity were previously reported. The objective of this study was to investigate the neurotransmitters glutamate and GABA in relation to impulsivity and aggression as expressed in the anterior cingulate cortex (ACC) in groups of female patients with BPD and ADHD, respectively. Associations of glutamate and GABA levels with further BPD (symptom severity) and ADHD aspects (hyperactivity and inattention) were exploratively evaluated. 1H MR spectra were acquired at 3T to determine glutamate to total creatine ratios (Glu/tCr) and GABA levels from the ACC in a BPD group (n=26), an ADHD group (n=22), and a healthy control (HC) group (n=30); all participants were females. Both patient groups showed higher scores on self-reported impulsivity, anger, and aggression compared with HCs. ACC GABA levels were significantly lower in ADHD than HC. Although measures of impulsivity were positively related to glutamate and negatively to GABA, for aggression only a negative correlation with GABA could be demonstrated. These data provide human in vivo evidence for the role of ACC Glu/tCr and GABA in impulsivity and aggression. If distinct associations of Glu/tCr and GABA for BPD and ADHD can be confirmed in future studies, this might yield implications for more specific pharmacological treatments. PMID:26040503

  5. 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.

  6. A model-based analysis of impulsivity using a slot-machine gambling paradigm.

    Science.gov (United States)

    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 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 (BIs), machines switches (MS), casino switches (CS), and double-ups (DUs). 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 (RL) 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 the impulsive traits of an individual. 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 PG. PMID:25071497

  7. Lewis rats have greater response impulsivity than Fischer rats.

    Science.gov (United States)

    Hamilton, Kristen R; Potenza, Marc N; Grunberg, Neil E

    2014-11-01

    Impulsivity, a tendency toward immediate action without consideration of future consequences, is associated with a wide array of problematic behaviors. Response impulsivity, a type of behaviorally-assessed impulsivity characterized by behavioral disinhibition, is also associated with health risk behaviors. Response impulsivity is distinct from choice impulsivity, which is characterized by intolerance for delay. Lewis rats have higher levels of choice impulsivity than Fischer rats (Anderson & Woolverton, 2005; Madden et al., 2008; Stein et al., 2012). However, no studies have examined whether Lewis and Fischer rats have different levels of response impulsivity. The present research examined response impulsivity in the two rat strains. Subjects were 16 male Lewis and Fischer rats. Rats' response impulsivity was measured using the Five Choice Serial Reaction Time Task (5-CSRTT). In addition, their locomotor activity was measured in locomotor activity chambers. Lewis rats had more premature responses than Fischer rats during the 5-CSRTT assessment [F(1, 14)=5.34, p<0.05], indicating higher levels of response impulsivity. Locomotor activity did not differ between rat strain groups [F(1, 14)=3.05, p=.10], suggesting that overall movement did not account for group differences in response impulsivity on the 5-CSRTT. It can be concluded from this research that Lewis rats have higher levels of response impulsivity than Fischer rats, and therefore provide a valid rat model of individual differences in impulsivity. PMID:24613059

  8. 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.

  9. 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…

  10. 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…

  11. 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.

  12. Losing control : Assaultive behavior as a predictor of impulse control disorders in young adults

    DEFF Research Database (Denmark)

    Leppink, Eric; Odlaug, Brian Lawrence

    2014-01-01

    OBJECTIVE: Assaultive behaviors are common among young people and have been associated with a range of other unhealthy, impulsive behaviors such as substance use and problem gambling. This study sought to determine the predictive ability of single assaultive incidents for impulse control disorders, an association that has yet to be examined, especially in young adults. METHODS: The authors conducted a university-wide email survey in the spring of 2011 on 6000 university students. The survey examined assaultive behavior and associated mental health variables (using a clinically validated screening instrument, the Minnesota Impulsive Disorders Interview), stress and mood states, and psychosocial functioning. RESULTS: The rate of response was 35.1% (n=2108). 109 (5.9%) participants reported that they had assaulted another person or destroyed property at some time in their lives. Compared with respondents without lifetime assaultive behavior, those with a history of assaultive or destructive behavior reported more depressive symptoms, more stress, and higher rates of a range of impulse control disorders (intermittent explosive disorder, compulsive sexual behavior, compulsive buying, and skin picking disorder). CONCLUSIONS: Assaultive behavior appears fairly common among college students and is associated with symptoms of depression and impulse control disorders. Significant distress and diminished behavioral control suggest that assaultive behaviors may often be associated with significant morbidity. Additional research is needed to develop specific prevention and treatment strategies for young adults attending college who report problems with assaultive behaviors.

  13. Attending at a Low Intensity Increases Impulsivity in an Auditory Sustained Attention to Response Task.

    Science.gov (United States)

    Roebuck, Hettie; Guo, Kun; Bourke, Patrick

    2015-12-01

    Why attention lapses during prolonged tasks is debated, specifically whether errors are a consequence of under-arousal or exerted effort. To explore this, we investigated whether increased impulsivity is associated with effortful processing by modifying the demand of a task by presenting it at a quiet intensity. Here, we consider whether attending at low but detectable levels affects impulsivity in a population with intact hearing. A modification of the Sustained Attention to Response Task was used with auditory stimuli at two levels: the participants' personal "lowest detectable" level and a "normal speaking" level. At the quiet intensity, we found that more impulsive responses were made compared with listening at a normal speaking level. These errors were not due to a failure in discrimination. The findings suggest an increase in processing time for auditory stimuli at low levels that exceeds the time needed to interrupt a planned habitual motor response. This leads to a more impulsive and erroneous response style. These findings have important implications for understanding the nature of impulsivity in relation to effortful processing. They may explain why a high proportion of individuals with hearing loss are also diagnosed with Attention Deficit Hyperactivity Disorder. PMID:26562860

  14. Sex differences in neurophysiological responses are modulated by attentional aspects of impulse control.

    Science.gov (United States)

    Omura, Kazufumi; Kusumoto, Kenji

    2015-11-01

    The amplitudes of the N2 and P3 components of event-related potentials (ERPs) may be influenced by personality traits such as impulsivity, and male/female differences may also have an effect. However, few studies have assessed the interaction between personality traits and the sex of the subject in these components. Therefore, in this study we evaluated sex differences in the amplitudes of the N2 and P3 ERP components during a continuous performance task, and their relation to impulse control. Twenty-seven healthy participants were asked to perform an AX-type continuous performance task, also known as a Go/Nogo task, during electroencephalographic recording. Participants then completed the Barratt impulsiveness scale (version 11; BIS-11), and the effortful control (EC) scale to self-report personality measures related to impulse control. We found that in the Nogo condition, males showed significantly larger N2 amplitudes than females in the frontal area. Interestingly, Nogo-N2 amplitudes were positively correlated with BIS-attentional subscale scores, but were negatively correlated with EC-attentional subscale scores, and both correlations were observed only in males. These results suggest that attentional aspects of impulse control modulate Nogo-N2 amplitude only in males. This modulatory effect may be related to a sex-specific inhibitory control mechanism acting during early stimulus evaluation. PMID:26473554

  15. 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.

  16. Impulsivity, risky behaviors and accidents in alcohol-dependent patients

    OpenAIRE

    Jakubczyk, Andrzej; Klimkiewicz, Anna; Wnorowska, Anna; Mika, Katarzyna; Bugaj, Marcin; Podgórska, Anna; Barry, Kristen; Blow, Frederic C.; Brower, Kirk J.; Wojnar, Marcin

    2012-01-01

    Impulsivity and alcohol drinking are both considered as important predictors of unintentional as well as intentional injuries. However, relationships of impulsivity with risky behaviors and a history of accidents have not been investigated in alcohol dependence. The aim of this study was to analyze relationships between the frequency of risky behaviors and level of behavioral as well as cognitive impulsivity in alcohol-dependent patients. By means of Barratt’s Impulsiveness Scale (BIS) and st...

  17. Stability of Impulsive Differential Equation with any Time Delay

    OpenAIRE

    Srivastava, Sanjay K.; Kanwalpreet Kaur

    2013-01-01

    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 descrip...

  18. Impulsivity and Personality Variables in Adolescents with Eating Disorders

    OpenAIRE

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

    2009-01-01

    Impulsivity among individuals with eating disorders (EDs) is associated with severe co-morbidities and poor treatment outcome. However, research investigating the construct of impulsivity in EDs is limited. The objectives of the present study were to characterize multiple dimensions of impulsivity in adolescents with eating disorders (EDs); determine if differences in impulsivity were associated with ED diagnosis and/or broader personality traits; and explore the relationship between impulsiv...

  19. Impulsivity and Risk Taking in Bipolar Disorder and Schizophrenia

    OpenAIRE

    Reddy, L Felice; Lee, Junghee; Davis, Michael C; Altshuler, Lori; Glahn, David C; Miklowitz, David J; Green, Michael F.

    2013-01-01

    Impulsive risk taking contributes to deleterious outcomes among clinical populations. Indeed, pathological impulsivity and risk taking are common in patients with serious mental illness, and have severe clinical repercussions including novelty seeking, response disinhibition, aggression, and substance abuse. Thus, the current study seeks to examine self-reported impulsivity (Barratt Impulsivity Scale) and performance-based behavioral risk taking (Balloon Analogue Risk Task) in bipolar disorde...

  20. Extreme Geoelectric Fields Induced By Magnetic Storm Sudden Impulses

    Science.gov (United States)

    Love, J. J.; Rigler, E. J.; Swidinsky, A.

    2014-12-01

    Large magnetic storms, as quantified by the Dst index, can produce geoelectric fields that are hazardous for the operation of electric power grids. The great storm of March 1989, for example, had the highest -Dst value of the 20th century. During the main phase of this storm, rapid magnetic variation induced geoelectric fields in the Earth's lithosphere that caused the complete collapse of the Canadian Hydro-Québec electric-power grid. In this study, we focus specifically on how sudden impulses in geomagnetic activity, those that occur during large storms, can induce geoelectric fields. These impulses can be seen during storm main phases, but they are most usually recognized as storm sudden commencements corresponding to the arrival, at Earth, of coronal mass ejections. We use a newly developed algorithm for estimating induced geoelectric fields from magnetic field variation recorded at ground-based observatories. We train the algorithm on 1-sec geomagnetic and geoelectric field data collected at Japanese observatories during the October 2003 Halloween storm. We then postdict geoelectric fields that would have been realized (but not directly measured at 1-sec resolution) in Japan during the 1989 Québec storm and during another intense storm that occurred in March 1991. The later storm is noteworthy, not because of its intense main phase, but because it commenced with a sudden impulse of enormous magnitude. For the first half minute of the 1991 storm, induced geoelectric fields far exceeded those realized during the 1989 storm. Recognizing the potential hazard, we also analyze a scenario geomagnetic time series of an extreme event sudden commencement, and we calculate the geoelectric fields that this scenario event might plausibly induce. Results show that substantial geoelectric field induction, possibly hazardous for electric power grids, can occur briefly but very abruptly as soon as a magnetic storm commences.

  1. Dopamine, Time, and Impulsivity in Humans

    OpenAIRE

    Pine, Alex; Shiner, Tamara; Seymour, Ben; Dolan, Raymond J.

    2010-01-01

    Disordered dopamine neurotransmission is implicated in mediating impulsiveness across a range of behaviors and disorders including addiction, compulsive gambling, attention-deficit/hyperactivity disorder, and dopamine dysregulation syndrome. Whereas existing theories of dopamine function highlight mechanisms based on aberrant reward learning or behavioral disinhibition, they do not offer an adequate account of the pathological hypersensitivity to temporal delay that forms a crucial behavioral...

  2. How Many Impulsivities? A Discounting Perspective

    Science.gov (United States)

    Green, Leonard; Myerson, Joel

    2013-01-01

    People discount the value of delayed and uncertain outcomes, and how steeply individuals discount is thought to reflect how impulsive they are. From this perspective, steep discounting of delayed outcomes (which fails to maximize long-term welfare) and shallow discounting of probabilistic outcomes (which fails to adequately take risk into account)…

  3. Impulse Plasma In Surface Engineering - a review

    Science.gov (United States)

    Zdunek, K.; Nowakowska-Langier, K.; Chodun, R.; Okrasa, S.; Rabinski, M.; Dora, J.; Domanowski, P.; Halarowicz, J.

    2014-11-01

    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.

  4. Arbitration between controlled and impulsive choices.

    Science.gov (United States)

    Economides, M; Guitart-Masip, M; Kurth-Nelson, Z; Dolan, R J

    2015-04-01

    The impulse to act for immediate reward often conflicts with more deliberate evaluations that support long-term benefit. The neural architecture that negotiates this conflict remains unclear. One account proposes a single neural circuit that evaluates both immediate and delayed outcomes, while another outlines separate impulsive and patient systems that compete for behavioral control. Here we designed a task in which a complex payout structure divorces the immediate value of acting from the overall long-term value, within the same outcome modality. Using model-based fMRI in humans, we demonstrate separate neural representations of immediate and long-term values, with the former tracked in the anterior caudate (AC) and the latter in the ventromedial prefrontal cortex (vmPFC). Crucially, when subjects' choices were compatible with long-run consequences, value signals in AC were down-weighted and those in vmPFC were enhanced, while the opposite occurred when choice was impulsive. Thus, our data implicate a trade-off in value representation between AC and vmPFC as underlying controlled versus impulsive choice. PMID:25573670

  5. 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,…

  6. 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.

  7. Designing a Stochastic Adaptive Impulsive Observer for Stochastic Linear and Nonlinear Impulsive Systems

    International Nuclear Information System (INIS)

    State observation (estimation) is a very important issue in system analysis and control. This paper develops a new observer called Stochastic Adaptive Impulsive Observer (SAIO) for the state estimation of impulsive systems. The proposed observer is applicable to linear and nonlinear stochastic impulsive systems. In addition, the effect of parametric uncertainty is considered and unknown parameters of the system are estimated by suitable adaptation laws. Impulsive system theory, particularly stochastic Lyapunov-like function, is used to analyze the stability and convergence of the state estimations. The main advantages of the proposed observer are: 1) it gives continuous estimation from discrete time measurements of the system output, and 2) it is useful for state estimation when continuous measurements are impossible or expensive. Simulation results show the effectiveness of the proposed observer and we believe that it has many applications in control and estimation theories.

  8. Instability of solutions of impulsive systems of differential equations

    Energy Technology Data Exchange (ETDEWEB)

    Bainov, D.D. [Academy of Medicine, Sofia (Bulgaria); Kulev, G.K. [Plovdiv Univ. (Bulgaria); Stamova, I.M. [Technical Univ., Sliven (Bulgaria)

    1996-08-01

    We consider instability of the zero solution of impulsive systems of differential equations with unfixed moments of the impulse effect. Piecewise continuous auxiliary functions are used which are analogues of the classical Lyapunov functions. An analogue of Chetaev`s theorem for systems of differential equations without impulses is proved and some corollaries are deduced.

  9. 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.

  10. Borderline personality disorder, impulsivity, and the orbitofrontal cortex.

    OpenAIRE

    Berlin, HA; Rolls, ET; Iversen, SD

    2005-01-01

    OBJECTIVE: Orbitofrontal cortex lesions produce disinhibited or socially inappropriate behavior and emotional irregularities. Characteristics of borderline personality disorder include impulsivity and affective instability. The authors investigated whether aspects of borderline personality disorder, in particular impulsivity, are associated with orbitofrontal cortex dysfunction. METHOD: Measures of personality, emotion, impulsivity, time perception, sensitivity to reinforcers, and spatial wor...

  11. 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.

  12. Why So Impulsive? White Matter Alterations Are Associated With Impulsivity in Chronic Marijuana Smokers

    OpenAIRE

    Gruber, Staci A; Silveri, Marisa M; Dahlgren, Mary Kathryn; Yurgelun-Todd, Deborah

    2011-01-01

    Difficulty monitoring and inhibiting impulsive behaviors has been reported in marijuana (MJ) smokers; neuroimaging studies, which examined frontal systems in chronic MJ smokers, have reported alterations during inhibitory tasks. Diffusion tensor imaging (DTI) provides a quantitative estimate of white matter integrity at the microstructural level. We applied DTI, clinical ratings, and impulsivity measures to explore the hypotheses that chronic, heavy MJ smokers would demonstrate alterations in...

  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 2?-carbomethoxy-3?(4-iodophenyl)tropane ([123I]?-CIT) as the tracer. The blind quantitative analysis revealed that the 5-HT specific binding of [123I]?-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. 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.

  15. Self-reported impulsivity, but not behavioral choice or response impulsivity, partially mediates the effect of stress on drinking behavior

    OpenAIRE

    Hamilton, Kristen R.; Ansell, Emily B; Reynolds, Brady; POTENZA, MARC N.; Sinha, Rajita

    2012-01-01

    Stress and impulsivity contribute to alcohol use, and stress may also act via impulsivity to increase drinking behavior. Impulsivity represents a multi-faceted construct and self-report and behavioral assessments may effectively capture distinct clinically relevant factors. The present research investigated whether aspects of impulsivity mediate the effect of stress on alcohol use. A community-based sample of 192 men and women was assessed on measures of cumulative stress, alcohol use, self-r...

  16. 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.

  17. 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

  18. Influence of current impulse on machining characteristics in EDM

    International Nuclear Information System (INIS)

    Electrical discharge machining (EDM) is a machining process transforming electric energy into thermal energy to remove materials. The current impulse is a very important factor for machining characteristics of EDM. A series of experiments were performed to investigate the influence of current impulse on machining characteristics. The features of current impulse have initial current, current rising slope and impulse pattern. The used patterns of current impulse included rectangular current impulse, trapezoidal current impulse and the Ist order current impulse. The machining characteristics are associated with relative wear ratio (RWR) and material removal rate (MRR). Experimental showed that using trapezoidal current impulse with small initial current or little current rising slope reduced relative wear ratio and material removal rate as well. However, larger relative wear ratio was obtained for workpiece of tungsten carbide when current rising slope was too little. Using the 1st order current impulse with 20 ?S current rising time can improve relative wear ratio about 30 % while remain material removal rate the same as rectangular current impulse for tungsten carbide

  19. Barratt Impulsivity and Neural Regulation of Physiological Arousal

    Science.gov (United States)

    Zhang, Sheng; Hu, Sien; Hu, Jianping; Wu, Po-Lun; Chao, Herta H.; Li, Chiang-shan R.

    2015-01-01

    Background Theories of personality have posited an increased arousal response to external stimulation in impulsive individuals. However, there is a dearth of studies addressing the neural basis of this association. Methods We recorded skin conductance in 26 individuals who were assessed with Barratt Impulsivity Scale (BIS-11) and performed a stop signal task during functional magnetic resonance imaging. Imaging data were processed and modeled with Statistical Parametric Mapping. We used linear regressions to examine correlations between impulsivity and skin conductance response (SCR) to salient events, identify the neural substrates of arousal regulation, and examine the relationship between the regulatory mechanism and impulsivity. Results Across subjects, higher impulsivity is associated with greater SCR to stop trials. Activity of the ventromedial prefrontal cortex (vmPFC) negatively correlated to and Granger caused skin conductance time course. Furthermore, higher impulsivity is associated with a lesser strength of Granger causality of vmPFC activity on skin conductance, consistent with diminished control of physiological arousal to external stimulation. When men (n = 14) and women (n = 12) were examined separately, however, there was evidence suggesting association between impulsivity and vmPFC regulation of arousal only in women. Conclusions Together, these findings confirmed the link between Barratt impulsivity and heightened arousal to salient stimuli in both genders and suggested the neural bases of altered regulation of arousal in impulsive women. More research is needed to explore the neural processes of arousal regulation in impulsive individuals and in clinical conditions that implicate poor impulse control. PMID:26079873

  20. A Delayed Impulse Control Strategy for Spacecraft Formations

    Science.gov (United States)

    Mok, Sung-Hoon; Choi, Yoonhyuk; Bang, Hyochoong; Leeghim, Henzeh

    2015-10-01

    An impulsive control strategy for spacecraft formation flying is suggested considering secular drift between satellites. The drift motion caused by orbital period difference affects impulsive correction. Preventing the drift has been treated as a natural effort in most of formation flying researches. However, this study proposes preserving the drift behavior by delaying the period-matching maneuver. The paper shows that the impulse delay could be effective under some conditions by reducing the required delta-v. Two impulsive control methods are designed by harnessing the drift in pure Keplerian orbits. By using a linear approximation, the proposed methods avoid iterative steps for obtaining the required impulse, so the new strategy can be implemented with less computational burden compared to numerical optimal solutions. Impulse magnitudes between an existing method and the proposed strategy are compared mathematically and the numerical simulation verifies that the impulse reduction could be achieved with the suggested methods.

  1. [Anti-impulsivity drugs and their mechanisms of action].

    Science.gov (United States)

    Ohmura, Yu; Tsutsui-Kimura, Iku; Yoshioka, Mitsuhiro

    2014-04-01

    Higher impulsivity could be a risk factor for drug addiction, criminal involvement, and suicide. Moreover, poor inhibitory control is observed in several psychiatric disorders such as attention-deficit/hyperactivity disorder, schizophrenia, and bipolar disorder. Thus it is preferred that clinical drugs have anti-impulsive effects in addition to the therapeutic effects on the primary disease. At least it is better to use clinical drugs that do not increase impulsivity. We have developed a 3-choice serial reaction time task and examined the effects of clinical drugs on impulsivity in rats using the task. We have found several anti-impulsive drugs (lithium, tandospirone, and milnacipran) and elucidated the mechanism of action in some of these drugs. For example, we demonstrated that milnacipran enhanced the control of impulsive action by activating D1-like receptors in the infralimbic cortex. In this review, we introduce recent advances in this field and suggest future directions to develop anti-impulsive drugs. PMID:25080806

  2. 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

  3. A preliminary case study of androgen receptor gene polymorphism association with impulsivity in women with alcoholism

    Directory of Open Access Journals (Sweden)

    Mettman DJ

    2014-03-01

    Full Text Available Daniel J Mettman, Merlin G Butler, Albert B Poje, Elizabeth C Penick, Ann M Manzardo Departments of Psychiatry and Behavioral Sciences and Pediatrics, MS 4015, Kansas University Medical Center, Kansas City, KS, USA Objective: The androgen receptor (AR gene, located on the X chromosome, contains a common polymorphism involving cytosine-adenine-guanine (CAG repeats, which impacts disease and could contribute to the unequal sex ratio in alcoholism. CAG repeats in the AR gene are known to correlate with impulsivity in males. We report the first preliminary study examining the association between the number of CAG repeats and measures of impulsivity in females with chronic alcoholism. Methods: A total of 35 women and 85 men with chronic alcoholism were previously recruited for a nutritional clinical trial, and 26 well-characterized females (19 African–American and seven Caucasian with alcoholism agreed to participate for genetic testing. Genomic deoxyribonucleic acid (DNA was isolated from peripheral blood and CAG repeats determined by analyzing polymerase chain reaction (PCR-amplified products, using the polymorphic AR gene assay. CAG repeat length was correlated with raw scores from the Barratt Impulsivity Scale, version 11 and the Alcoholism Severity Scale. Results: CAG repeat lengths were significantly longer in Caucasian alcoholic women compared with African–Americans, and the average number of CAG repeats were significantly, positively correlated (P<0.05 with impulsivity scores. Women with average CAG repeat length (CAGave ?18, representing the upper quartile of the repeat range, showed significantly greater mean raw impulsivity scores. CAG repeat length appeared to have less effect in African–American compared with Caucasian women, possibly due to a shorter average repeat length. Conclusion: We found an association between the number of CAG repeats and impulsivity in females with chronic alcoholism, specifically in women with CAGave ?18, seen more commonly in Caucasian compared with African–American women. Keywords: AR gene, CAG repeat, African-American, Caucasian, behavior

  4. 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.

  5. 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.

  6. 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

  7. Pinning impulsive control algorithms for complex network

    International Nuclear Information System (INIS)

    In this paper, we further investigate the synchronization of complex dynamical network via pinning control in which a selection of nodes are controlled at discrete times. Different from most existing work, the pinning control algorithms utilize only the impulsive signals at discrete time instants, which may greatly improve the communication channel efficiency and reduce control cost. Two classes of algorithms are designed, one for strongly connected complex network and another for non-strongly connected complex network. It is suggested that in the strongly connected network with suitable coupling strength, a single controller at any one of the network's nodes can always pin the network to its homogeneous solution. In the non-strongly connected case, the location and minimum number of nodes needed to pin the network are determined by the Frobenius normal form of the coupling matrix. In addition, the coupling matrix is not necessarily symmetric or irreducible. Illustrative examples are then given to validate the proposed pinning impulsive control algorithms

  8. 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...

  9. Acoustic radiation force impulse imaging for aneurysms

    OpenAIRE

    Tierney, Áine P.; Dumont, Douglas; Callanan, Anthony; McGloughlin, Timothy M

    2009-01-01

    A method for reliable, noninvasive estimation of Abdominal Aortic Aneurysms (AAA) wall mechanics may be a useful clinical tool for rupture prediction. An in vitro AAA model was developed from an excised porcine aorta, with elastase treatment. The AAA model behaviour was analysed using Acoustic Radiation Force Impulse (ARFI) imaging techniques to generate displacements in both aneurysmal and normal aortic tissue. The incremental modulus of the arteries was indicative of ...

  10. Acoustic radiation force impulse of the liver

    OpenAIRE

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

    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 qualita...

  11. Cigarette cravings, impulsivity and the brain

    Directory of Open Access Journals (Sweden)

    Stéphane 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.

  12. Cigarette Cravings, Impulsivity, and the Brain.

    Science.gov (United States)

    Potvin, Stéphane; Tikàsz, Andràs; Dinh-Williams, Laurence Lê-Anh; Bourque, Josiane; Mendrek, Adrianna

    2015-01-01

    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 impede their self-control capacities and promote 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, planning/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-cingulate 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. PMID:26441686

  13. Cigarette Cravings, Impulsivity, and the Brain

    Science.gov (United States)

    Potvin, Stéphane; Tikàsz, Andràs; Dinh-Williams, Laurence Lê-Anh; Bourque, Josiane; Mendrek, Adrianna

    2015-01-01

    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 impede their self-control capacities and promote 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, planning/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-cingulate 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.

  14. 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

  15. 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 ?-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 ?-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.)

  16. Principles and Applications of Broadband Impulsive Vibrational Spectroscopy.

    Science.gov (United States)

    Liebel, M; Schnedermann, C; Wende, T; Kukura, P

    2015-09-10

    We present an experimental setup for recording vibrational coherences and thereby Raman spectra of molecules in their ground and excited electronic states over the 50-3000 cm(-1) spectral range using broadband impulsive vibrational spectroscopy. Our approach relies on the combination of a light continuum probe, which drastically reduces experimental complexity compared to frequency domain based techniques. We discuss the parameters determining vibrational coherence amplitudes, outline how to optimize the experimental setup including approaches aimed at conclusively assigning vibrational coherences to specific electronic states, and provide a clear comparison with existing techniques. To demonstrate the applicability of our spectroscopic approach we conclude with several examples revealing the evolution of vibrational coherence in rhodopsin and ?-carotene. PMID:26262557

  17. Magneto-plasma waveguide

    Science.gov (United States)

    Hur, Min Sup; Wurtele, Jonathan

    2003-10-01

    A new method of guiding electromagnetic radiation with plasmas is presented. The concept uses a homogeneous plasma and an inhomogeneous external magnetic field to make a guiding channel for electromagnetic (EM) radiation. The basic idea is to use the external magnetic field to create a transverse variation in the refractive index. This is possible since the refractive index of the magnetized plasma is dependent on the external magnetic field as well as the plasma density. Particle in cell simulations with XOOPIC show that the idea works as expected. In the simulations, a right-hand-polarized microwave pulse was launched into a uniform density plasma with an axial applied magnetic field whose intensity varied transversly. The results agreed well with an analysis based on an envelope equation for the transverse spot size of the wave. Owing to the resonance in the dispersion relation, the index of refraction exhibits much sharper gradients then the applied magnetic field. Using this fact, a simple theory based on specifying the boundary condition at a magnetic wall (defined by the radius where the cut-off is reached) yields a dispersion relation which agrees well with simulation results. A magnetic wiggler, which satisfies the Ampere's law with zero current (curl B=0), was also used. The wave intensity is well-conserved in the periodic focusing and defocusing channel created by a superposition of the wiggler and a uniform axial field. Possible applications of this magnetic guiding scheme are discussed.

  18. 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

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

    CERN Document Server

    Rach?nková, 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...

  20. 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.

  1. 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...

  2. 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...

  3. Impulsive consumption and reflexive thought: Nudging ethical consumer behavior

    OpenAIRE

    Lades, Leonhard K.

    2012-01-01

    The paper deals with impulsive consumption and highlights the roles that cognitive and motivational aspects of reflexive thought (namely self-control and self-image motives, respectively) play in intertemporal decisions. While self-control inhibits individuals from consuming impulsively, self-image motives can induce impulsive consumption. Based on recent neuroscientific findings about 'wanting'-'liking' dissociations, the paper presents a potential motivational mechanism underlying such impu...

  4. Lyapunov Control of Quantum Systems with Impulsive Control Fields

    OpenAIRE

    Wei Yang; Jitao Sun

    2013-01-01

    We investigate the Lyapunov control of finite-dimensional quantum systems with impulsive control fields, where the studied quantum systems are governed by the Schrödinger equation. By three different Lyapunov functions and the invariant principle of impulsive systems, we study the convergence of quantum systems with impulsive control fields and propose new results for the mentioned quantum systems in the form of sufficient conditions. Two numerical simulations are presented to illustrate the ...

  5. 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...

  6. Neural circuitry of impulsivity in a cigarette craving paradigm

    OpenAIRE

    StephanePotvin; JosianeBourque; AdriannaMendrek

    2013-01-01

    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 Sc...

  7. Cigarette smoking and measures of impulsivity in a college sample

    OpenAIRE

    Balevich, Emily C.; Wein, Naftali D.; Flory, Janine D.

    2013-01-01

    An association between impulsivity and smoking has been consistently reported in the literature, but few studies have examined how distinct dimensions of impulsivity may relate differentially to smoking initiation versus persistent smoking. The aim of the current study was to examine the relationship between self-report and behavioral measures of impulsivity and smoking status in college students. Participants (n=243) completed a self-report history of tobacco use, two self-report measures of...

  8. Neural Circuitry of Impulsivity in a Cigarette Craving Paradigm

    OpenAIRE

    Bourque, Josiane; Mendrek, Adrianna; Dinh-Williams, Laurence; Potvin, Stéphane

    2013-01-01

    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 Sc...

  9. Personality and Alcohol Use: The Role of Impulsivity

    OpenAIRE

    Shin, Sunny Hyucksun; Hong, Hyokyoung Grace; Jeon, Sae-Mi

    2011-01-01

    Research has shown that personality traits associated with impulsivity influence alcohol use during emerging adulthood, yet relatively few studies have examined how distinct facets of impulsivity are associated with alcohol use and abuse. We examine the influence of impulsivity traits on four patterns of alcohol use including frequency of alcohol use, alcohol-related problems, binge drinking, and alcohol use disorders (AUDs) in a community sample of young individuals (N = 190). In multivariat...

  10. Influence of demographic and individual difference factors on impulse buying

    Directory of Open Access Journals (Sweden)

    Mirela Mihi?

    2010-06-01

    Full Text Available The main purpose of the paper is to determine the correlation of consumers’ demographic or socioeconomic characteristics and individual difference factors on the impulse buying behavior with respect to a number of single impulsivity indicators and one collective indicator. The paper consists of theoretical and research aspects. The first part encompasses theoretical insights into the secondary research regarding impulse buying while the practical part presents the methodology and primary research results. With respect to the subject matter, research goals as well as previous findings and primary research results, corresponding hypotheses were set and mainly confirmed. The results showed that demographic factors, such as the age and working status, are related to most impulse buying indicators and to the impulsivity collective indicator. However, household income produced opposite results. Household income proved to have no major influence on the majority of impulse buying indicators but to be related noticeably to the collective impulsivity indicator, indicating that this result should be regarded with caution. Research results also pointed to the fact that the majority of individual indicators (innovativeness, tendency to the fashionable and shopping enjoyment are positively and negatively related to the impulse buying behavior and that individual difference factors have a greater influence on impulse buying than do demographic characteristics. The paper also summarizes research limitations as well as the work contribution and future research guidelines.

  11. 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

  12. Energetic electrons in impulsive solar flares

    International Nuclear Information System (INIS)

    A new analysis was made of a thermal flare model proposed by Brown, Melrose, and Spicer (1979) and Smith and Lilliequist (1979). They assumed the source of impulsive hard X-rays to be a plasma at a temperature of order 10 to the 8th power K, initially located at the apex of a coronal arch, and confined by ion-acoustic turbulence in a collisionless conduction front. Such a source would expand at approximately the ion-sound speed, C sub S square root of (k T sub e/m sub i), until it filled the arch. Brown, Melrose, and Spicer and Smith and Brown (1980) argued that the source assumed in this model would not explain the simultaneous impulsive microwave emission. In contrast, the new results presented herein suggest that this model leads to the development of a quasi-Maxwellian distribution of electrons that explains both the hard X-ray and microwave emissions. This implies that the source sizes can be determined from observations of the optically-thick portions of microwave spectra and the temperatures obtained from associated hard X-ray observations. In this model, the burst emission would rise to a maximum in a time, t sub r, approximately equal to L/c sub s, where L is the half-length of the arch. New observations of these impulsive flare emissions were analyzed herein to test this prediction of the model. Observations made with the Solar Maximum Mission spacecraft and the Bern Radio Observatory are in good agreement with the model

  13. Electron acceleration in impulsive solar flares

    International Nuclear Information System (INIS)

    Simultaneous observations of the hard X-ray, microwave, and type III and DCIM (decimetric)radio bursts associated with the 1978 December 4 solar flare have been used to study the physical parameters relevant to the acceleration and propagation of energetic electrons during the impulsive phase of a solar flare. The hard X-ray observations were made with the X-ray spectrometer aboard the ISEE 3 spacecraft. The radio spectra in metric and decimetric bands were recorded with the radiospectrograph located at Durnten, near Zurich, Switzerland. The microwave observations were made at the Sagamore Hill and Bern observatories. The three metric type III bursts coincided with the three most prominent hard X-ray peaks. This is the fist time a clear one-to-one association between single type III bursts and hard X-ray peaks has been established. The average delay of the type III bursts with respect to the X-ray peaks was 0.5 s. The harder the X-ray spectrum, the higher was the drift rate of the associated type III burst. The characteristic electron energies inferred from the drift rate are of the order of 70 keV. The observed increase in the high-frequency cutoff of the metric type III bursts during the impulsive phase has been examined in terms of the decreasing altitude of the electron acceleration/injection region, the increasing hardness of the electron spectrum, and the decreasing acceleration time. A pulsating decimetric continuum (DCIM) was also found to be present during and before the impulsive phase. The DCIM source seems to coincide spatially with the electron acceleration region and the (projected) origin of the associated type II shock.ction region

  14. 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.

  15. Graph completions for impulsive feedback controls

    OpenAIRE

    Bressan, Alberto; Mazzola, Marco

    2014-01-01

    The paper considers impulsive control systems, where the evolution equation depends linearly on the time derivatives of the control function. The basic theory of "graph completions" is here extended to control functions in feedback form. In the case where the control u=u(t,x) is piecewise smooth, with a jump along a hypersurface ? in the t-x space, results are proved on the existence and uniqueness of solutions, and on their approximation by means of smooth feedbacks. The paper is concluded w...

  16. 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

  17. Impulse Noise removal in Digital Images

    Directory of Open Access Journals (Sweden)

    M.JayaManmadhaRao,

    2010-10-01

    Full Text Available In this paper, we introduce a new class of filter, the modified spatial median filter (MSMF for the removal of impulse noise in digital images. The proposed filter is compared with four different filtering algorithms based on their ability to reconstruct noise-affected images. In-order to better appraise the noise cancellation behavior of our filter from the point of view of human perception, we perform edge detection using canny filter. Experimental results show that the filtering performance of the proposed approach is very satisfactory.

  18. Génération et application des impulsions Attosecondes

    OpenAIRE

    Diveki, Zsolt

    2011-01-01

    En vue de la capture de réearrangements électroniques au sein d'une molécule ou au cours de réactions chimiques il est indispensable de développer un dispositif dont la résolution temporelle est attoseconde (as 1 as = 10?18 s). La voie naturelle est de rechercher des impulsions lumineuses dans cette gamme de durée. Leur fréquence centrale doit alors être dans la gamme UVX et couvrir plusieurs dizaines d'eVs. De plus, ses composantes fréquencielles doivent être synchronisées. Le processus de g...

  19. [Impulse control disorders and Parkinson's disease].

    Science.gov (United States)

    Burkhard, P R; Catalano-Chiuvé, S; Gronchi-Perrin, A; Berney, A; Vingerhoets, F J G; Lüscher, C

    2008-05-01

    A variety of behavioral disorders occurring abruptly in patients with Parkinson's disease (PD) has been recently published and attracted considerable attention in the press. Taking the form of pathological gambling, compulsive shopping, addiction to Internet and to other recreational activities, hypersexuality or bulimia, impulse control disorders (ICD) related to PD are probably more frequent than previously appreciated and may have consequences as spectacular as disastrous for the involved patients. ICD are currently viewed as particular adverse reactions to antiparkinsonian medications, notably to dopamine agonists, and, accordingly, tend to improve or disappear when PD therapy is appropriately adjusted. PMID:18630168

  20. High power impulse magnetron sputtering discharge

    OpenAIRE

    Gudmundsson, J. T.; N. Brenning; 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...

  1. 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.

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

    DEFF Research Database (Denmark)

    Sturm, Bob L.; Defrance, Guillaume

    2010-01-01

    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 same number of sound rays per unit volume throughout the room. We compare the performance of two methods of greedy sparse approximation --- matching pursuit (MP) and orthogonal MP (OMP) --- for estim...

  3. Usage of measured reverberation tail in a binaural room impulse response synthesis

    DEFF Research Database (Denmark)

    Markovic, Milos; Olesen, Søren Krarup; Madsen, Esben; Hoffmann, Pablo F.; Hammershøi, Dorte

    2011-01-01

    The aim of the modern communication technologies is an immersive experience. One of the applications that should provide the feeling of being together and sharing the same environment during the communication process is BEAMING. The goal of this paper is to improve audible spatial impression 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 simulat...

  4. 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)

  5. Compulsivity and Impulsivity in Pathological Gambling: Does a Dimensional-Transdiagnostic Approach Add Clinical Utility to DSM-5 Classification?

    Science.gov (United States)

    Bottesi, Gioia; Ghisi, Marta; Ouimet, Allison J; Tira, Michael D; Sanavio, Ezio

    2015-09-01

    Although the phenomenology of Pathological Gambling (PG) is clearly characterized by impulsive features, some of the Diagnostic and Statistical Manual of Mental Disorder (DSM-5) criteria for PG are similar to those of Obsessive Compulsive Disorder (OCD). Therefore, the compulsive-impulsive spectrum model may be a better (or complementary) fit with PG phenomenology. The present exploratory research was designed to further investigate the compulsive and impulsive features characterizing PG, by comparing PG individuals, alcohol dependents (ADs), OCD patients, and healthy controls (HCs) on both self-report and cognitive measures of compulsivity and impulsivity. A better understanding of the shared psychological and cognitive mechanisms underlying differently categorized compulsive and impulsive disorders may significantly impact on both clinical assessment and treatment strategies for PG patients. With respect to self-report measures, PG individuals reported more compulsive and impulsive features than did HCs. As regards motor inhibition ability indices, PG individuals and HCs performed similarly on the Go/No-go task and better than AD individuals and OCD patients. Results from the Iowa Gambling Task highlighted that PG, AD, and OCD participants performed worse than did HCs. An in-depth analysis of each group's learning profile revealed similar patterns of impairment between PG and AD individuals in decision-making processes. Current findings support the utility of adopting a dimensional-transdiagnostic approach to complement the DSM-5 classification when working with PG individuals in clinical practice. Indeed, clinicians are encouraged to assess both compulsivity and impulsivity to provide individualized case conceptualizations and treatment plans focusing on the specific phenomenological features characterizing each PG patient. PMID:24863627

  6. 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

  7. 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.

  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. 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,…

  10. 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.

  11. 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.

  12. A Systematic Review of Impulse Control Disorders in Parkinson's Disease

    DEFF Research Database (Denmark)

    Callesen, Mette Buhl; Scheel-Krüger, JØrgen

    2013-01-01

    Throughout the past decade it has been recognized that dopaminergic medication administered to remedy motor symptoms in Parkinson's disease is associated with an enhanced risk for impulse control disorders and related compulsive behaviors such as hobbyism, punding, and the dopamine dysregulation syndrome. These complications are relatively frequent, affecting 6-15.5% of patients, and they most often appear, or worsen, after initiation of dopaminergic therapy or dosage increase. Recently, impulse control disorders have also been associated with subthalamic nucleus deep brain stimulation. Here we present a systematic overview of literature published between 2000 and January 2013 reporting impulse control disorders in Parkinson's disease. We consider prevalence rates and discuss the functional neuroanatomy, the impact of dopamine-serotonin interactions, and the cognitive symptomatology associated with impulse control disorders in Parkinson's disease. Finally, perspectives for future research and management of impulse control disorders in Parkinson's disease are discussed.

  13. Effect of nicotine on negative affect among more impulsive smokers.

    Science.gov (United States)

    Doran, Neal; McChargue, Dennis; Spring, Bonnie; VanderVeen, Joe; Cook, Jessica Werth; Richmond, Malia

    2006-08-01

    In the present study, the authors tested the hypothesis that nicotine would provide greater relief from negative affect for more impulsive smokers than for less impulsive smokers. Euthymic adult smokers (N=70) participated in 2 laboratory sessions, during which they underwent a negative mood induction (music + autobiographical memory), then smoked either a nicotinized or de-nicotinized cigarette. Mixed-effects regression yielded a significant Impulsivity x Condition (nicotinized vs. de-nicotinized) x Time interaction. Simple effects analyses showed that heightened impulsivity predicted greater negative affect relief after smoking a nicotinized cigarette but not after smoking a de-nicotinized cigarette. These data suggest that nicotine may be a disproportionately powerful negative reinforcer for highly impulsive smokers, promoting higher levels of nicotine dependence and inhibiting smoking cessation. PMID:16893271

  14. Group vs. single mindfulness meditation: exploring avoidance, impulsivity, and weight management in two separate mindfulness meditation settings.

    Science.gov (United States)

    Mantzios, Michail; Giannou, Kyriaki

    2014-07-01

    Recent research has identified that mindfulness meditation in group settings supports people who are trying to lose weight. The present research investigated mindfulness meditation in group and individual settings, and explored the potential impact on weight loss and other factors (i.e. mindfulness, impulsivity, and avoidance) that may assist or hinder weight loss. Specifically, the hypotheses tested were that the group setting assisted dieters more than the individual setting by reducing weight, cognitive-behavioral avoidance, and impulsivity and by increasing mindfulness. Participants (n?=?170) who were trying to lose weight were randomly assigned to practice meditation for 6 weeks within a group or independently. Measurements in mindfulness, cognitive-behavioral avoidance, impulsivity, and weight occurred twice (pre- and post-intervention). Results indicated that participants in the group setting lost weight and lowered their levels of cognitive-behavioral avoidance, while impulsivity and mindfulness remained stable. On the other hand, participants in the individual condition lost less weight, while there was an increase in cognitive-behavioral avoidance and mindfulness scores, but a decrease in impulsivity. Seeing that benefits and limitations observed in group settings are not replicated when people meditate alone, this study concluded that mindfulness meditation in individual settings needs to be used with caution, although there are some potential benefits that could aid future weight loss research. PMID:24585500

  15. 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. Copyright © 2013 John Wiley & Sons, Ltd. PMID:26468625

  16. The functional anatomy of impulse control disorders.

    Science.gov (United States)

    Probst, Catharina C; van Eimeren, Thilo

    2013-10-01

    Impulsive-compulsive disorders such as pathological gambling, hypersexuality, compulsive eating, and shopping are side effects of the dopaminergic therapy for Parkinson's disease. With a lower prevalence, these disorders also appear in the general population. Research in the last few years has discovered that these pathological behaviors share features similar to those of substance use disorders (SUD), which has led to the term "behavioral addictions". As in SUDs, the behaviors are marked by a compulsive drive toward and impaired control over the behavior. Furthermore, animal and medication studies, research in the Parkinson's disease population, and neuroimaging findings indicate a common neurobiology of addictive behaviors. Changes associated with addictions are mainly seen in the dopaminergic system of a mesocorticolimbic circuit, the so-called reward system. Here we outline neurobiological findings regarding behavioral addictions with a focus on dopaminergic systems, relate them to SUD theories, and try to build a tentative concept integrating genetics, neuroimaging, and behavioral results. PMID:23963609

  17. Complex dynamics in a linear impulsive system

    International Nuclear Information System (INIS)

    The dynamical behavior of a linear impulsive system is discussed by means of both theoretical and numerical ways. This paper investigates the existence and stability of the equilibrium and period-one solution, the discontinuous jumps of eigenvalues, and the conditions for system possessing infinite period-two, period-three, and period-six solutions. By using discrete maps, the conditions of existence for Neimark-Sacker bifurcation are derived. In particular, chaotic behavior in the sense of Marotto's definition of chaos is rigorously proven. Moreover, some detailed numerical results of the phase portraits, the periodic solutions, the bifurcation diagram, and the chaotic attractors, which are illustrated by some interesting examples, are in good agreement with the theoretical analysis.

  18. Optimal Stochastic Impulse Control with Delayed Reaction

    International Nuclear Information System (INIS)

    We study impulse control problems of jump diffusions with delayed reaction. This means that there is a delay ?>0 between the time when a decision for intervention is taken and the time when the intervention is actually carried out. We show that under certain conditions this problem can be transformed into a sequence of iterated no-delay optimal stopping problems and there is an explicit relation between the solutions of these two problems. The results are illustrated by an example where the problem is to find the optimal times to increase the production capacity of a firm, assuming that there are transaction costs with each new order and the increase takes place ? time units after the (irreversible) order has been placed

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. Dynamic behaviors of the periodic Lotka-Volterra competing system with impulsive perturbations

    International Nuclear Information System (INIS)

    In this paper, we investigate a classical periodic Lotka-Volterra competing system with impulsive perturbations. The conditions for the linear stability of trivial periodic solution and semi-trivial periodic solutions are given by applying Floquet theory of linear periodic impulsive equation, and we also give the conditions for the global stability of these solutions as a consequence of some abstract monotone iterative schemes introduced in this paper, which will be also used to get some sufficient conditions for persistence. By using the method of coincidence degree, the conditions for the existence of at least one strictly positive (componentwise) periodic solution are derived. The theoretical results are confirmed by a specific example and numerical simulations. It shows that the dynamic behaviors of the system we consider are quite different from the corresponding system without pulses

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

    DEFF Research Database (Denmark)

    Olsen, Svein Ottar; Tudoran, Ana Alina

    2015-01-01

    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 seeking tendency (VST), and the Big Five personality traits within one integrated framework. Based on data from a nationally representative sample of 1,644 Norwegian adults, the results show that while IBT and VST might be correlated, they differ significantly with respect to two major personality aspects: 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.

  5. The influence of impulsiveness on binge eating and problem gambling: A prospective study of gender differences in Canadian adults.

    Science.gov (United States)

    Farstad, Sarah M; von Ranson, Kristin M; Hodgins, David C; El-Guebaly, Nady; Casey, David M; Schopflocher, Don P

    2015-09-01

    This study investigated the degree to which facets of impulsiveness predicted future binge eating and problem gambling, 2 theorized forms of behavioral addiction. Participants were 596 women and 406 men from 4 age cohorts randomly recruited from a Canadian province. Participants completed self-report measures of 3 facets of impulsiveness (negative urgency, sensation seeking, lack of persistence), binge-eating frequency, and problem-gambling symptoms. Impulsiveness was assessed at baseline, and assessments of binge eating and problem gambling were followed up after 3 years. Weighted data were analyzed using zero-inflated negative binomial and Poisson regression models. We found evidence of transdiagnostic and disorder-specific predictors of binge eating and problem gambling. Negative urgency emerged as a common predictor of binge eating and problem gambling among women and men. There were disorder-specific personality traits identified among men only: High lack-of-persistence scores predicted binge eating and high sensation-seeking scores predicted problem gambling. Among women, younger age predicted binge eating and older age predicted problem gambling. Thus, there are gender differences in facets of impulsiveness that longitudinally predict binge eating and problem gambling, suggesting that treatments for these behaviors should consider gender-specific personality and demographic traits in addition to the common personality trait of negative urgency. (PsycINFO Database Record PMID:25961146

  6. A musculoskeletal model of human locomotion driven by a low dimensional set of impulsive excitation primitives

    Directory of Open Access Journals (Sweden)

    Massimo Sartori

    2013-06-01

    Full Text Available Human locomotion has been described as being generated by an impulsive (burst-like excitation of groups of musculotendon units, with timing dependent on the biomechanical goal of the task. Despite this view is supported by many experimental observations on specific locomotion tasks, it is still unknown if the same impulsive controller (i.e. a low-dimensional set of time-delayed excitation primitives can be used as input drive for large musculoskeletal models across different human locomotor tasks. For this purpose, we extracted, with non-negative matrix factorization, five non-negative factors from a large sample of muscle EMG signals in two healthy subjects during four motor tasks including walking, running, sidestepping, and crossover cutting maneuvers. The extracted non-negative factors were then averaged and parameterized to obtain task-generic Gaussian-shaped impulsive excitation curves or primitives. These were used to drive a subject-specific musculoskeletal model of the human lower extremity. Results showed that the same set of five impulsive excitation primitives could be used to predict the dynamics of 34 musculotendon units and the resulting hip, knee and ankle joint moments (i.e. NRMSE = 0.18±0.08, and R2 = 0.73±0.22 across all tasks and subjects without substantial loss of accuracy with respect to using experimental EMG recordings (i.e. NRMSE = 0.16±0.07, and R2 = 0.78±0.18 across all tasks and subjects. Results support the hypothesis that dynamically different motor tasks might share similar neuromuscular control strategies. This might have implications in neurorehabilitation technologies such as human-machine interfaces for the torque-driven, proportional control of powered prostheses and orthoses. In this, device control commands (i.e. predicted joint torque could be derived without direct experimental data but relying on simple parameterized Gaussian-shaped curves, thus decreasing the input drive complexity and the number of needed sensors.

  7. Religiosity and Impulsivity in Mental Health: Is There a Relationship?

    Science.gov (United States)

    Caribé, André C; Rocha, Marlos Fernando Vasconcelos; Junior, Davi Félix Martins; Studart, Paula; Quarantini, Lucas C; Guerreiro, Nicolau; Miranda-Scippa, Ângela

    2015-07-01

    Our aim is to evaluate the relationship between religiosity and impulsivity in patients with mental illness who had attempted suicide and in healthy individuals. This is a cross-sectional study that included 61 healthy individuals and 93 patients. The instruments used were a sociodemographic data questionnaire, the Mini International Neuropsychiatric Interview, the Barratt Impulsiveness Scale, and the Duke University Religion Index. The healthy individuals presented higher scores in the religiosity domains (organizational, p = 0.028; non-organizational, p = 0.000; intrinsic, p = 0.000). The patients presented higher scores in the impulsivity dimensions (attentional, p = 0.000; motor, p = 0.000; absence of planning, p = 0.000). In the patient group, intrinsic religiosity had a significant inverse relationship with total impulsivity (p = 0.023), attentional (p = 0.010), and absence of planning (p = 0.007), even after controlling for sociodemographic variables. Healthy individuals were more religious and less impulsive than patients. The relationship between religiosity, impulsiveness, and mental illness could be bidirectional; that is, just as mental illness might impair religious involvement, religiosity could diminish the expression of mental illness and impulsive behaviors. PMID:26020819

  8. 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.

  9. 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

  10. Synchronization of impulsively coupled complex systems with delay.

    Science.gov (United States)

    Sun, Wen; Austin, Francis; Lü, Jinhu; Chen, Shihua

    2011-09-01

    This paper investigates the synchronization of complex systems with delay that are impulsively coupled at discrete instants only. Based on the comparison theorem of impulsive differential system, a distributed impulsive control scheme is proposed to achieve the synchronization for systems with delay. In the control strategy, the influence of all nodes to network synchronization relies on its weight. The proposed control scheme is applied to the chaotic delayed Hopfield neural networks and numerical simulations are presented to demonstrate the effectiveness of the proposed scheme. PMID:21974658

  11. Neurobiologia dos transtornos do controle dos impulsos / The neurobiology of impulse control disorders

    Scientific Electronic Library Online (English)

    Wendol A, Williams; Marc N, Potenza.

    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. Abstract in english 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 sea [...] rched 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.

  12. 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.

  13. Dynamics of Dense Magnetized Plasma Streams and their Interaction with Material Surfaces: Comparative Studies with Magnetoplasma Compressor (MPC) and Quasi-Steady-State Plasma Accelerator QSPA Kh-50

    International Nuclear Information System (INIS)

    The quasi-steady-state plasma accelerator QSPA Kh-50 and short-pulsed magnetoplasma compressor (MPC) have been used for comparative studies of plasma-surface interaction and materials erosion issues, development of recommendations for fusion reactor materials and in numerical models for validation of predictive codes. The main advantage of QSPA in simulation experiments is possibility of generation of long magnetized pulse plasma streams with the pulse duration of 0.2-0.3 ms, the ion impact energy of 0.9 keV, the heat loads up to 20 MJ/m2, and the plasma parameter betta up to 0.3, which combination is not achievable in other types of plasma sources. Using within the framework of one problem both short- (?1-3 ?s) and long pulsed (300 ?s) plasma devices permitted to investigate the plasma effects on materials surfaces in a wide range of plasma pulse duration with varied energy and particle loads to the exposed surfaces. Crack patterns (major- and micro-type) in tungsten targets and cracking thresholds (both threshold energy load for the cracking onset and threshold target temperature related to ductile-to-brittle transition) as well as residual stresses after repetitive plasma pulses have been studied for different tungsten grades and, in particular, for a deformed W material, which is considered as the ITER-reference grade. The thickness of major- and micro-cracks, the network distance as well as the penetration of cracks into the material depth are analyzed. Comparisons of the cracking failure of deformed tungsten with behaviour of sintered W samples are performed. Results of QSPA plasma exposures are compared with short pulse PSI experiments with pulsed plasma gun and dense plasma-focus facilities, aiming at features of surface damage and tungsten impurities behavior in near-surface plasma in front of the target. (author)

  14. Eyes wide shopped: shopping situations trigger arousal in impulsive buyers.

    Science.gov (United States)

    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 hedonic shopping situations as well as for utilitarian shopping situations. Importantly, the effect did not emerge for non-shopping scenes. Furthermore, we demonstrated that arousal of impulsive buyers is independent from cognitive evaluation of scenes in the pictures. PMID:25489955

  15. 3D model of impulse compaction of moulding sands model

    Directory of Open Access Journals (Sweden)

    M. Ganczarek

    2008-04-01

    Full Text Available A mathematical 3D model is presented, fully describing the impulse compaction process of moulding sands. The model is based on the models of the impulse head dynamics as well as of the deformation and compaction processes of moulding sand. The deformation and compaction processes were modelled on the grounds of the viscoelastic rheological model of moulding sand. It was found that knowing the and coefficients characterising viscous and elastic properties of moulding sand makes the necessary and sufficient condition for simulation testing of the developed model. The coefficients can be determined by ultrasonic testing of moulding sand. The simulation and experimental research of the impulse compaction process proved that the developed model describes the impulse compaction process very well.

  16. Existence and uniqueness of solutions to impulsive fractional differential equations

    OpenAIRE

    Boualem Attou Slimani; Mouffak Benchohra

    2009-01-01

    In this article, we establish sufficient conditions for the existence of solutions for a class of initial value problem for impulsive fractional differential equations involving the Caputo fractional derivative.

  17. 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

    2010-01-01

    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.

  18. Pinning impulsive synchronization of complex-variable dynamical network

    Science.gov (United States)

    Wu, Zhaoyan; Liu, Danfeng; Ye, Qingling

    2015-01-01

    In this paper, pinning combining with impulsive control scheme is adopted to investigate the synchronization of complex-variable dynamical network. Based on the Lyapunov function method and mathematical analysis technique, sufficient conditions for achieving synchronization is first analytically derived. This result extends the condition derived for real-variable dynamical network to complex-variable network. Further, adaptive strategy is adopted to relax the restrictions on the impulsive intervals and reduce the control cost. Noticeably, the proposed adaptive pinning impulsive control scheme is universal for different dynamical networks to some extent. The impulsive instants are chosen by solving a series of maximum problems subject to the derived conditions. Several numerical simulations are performed to illustrate the effectiveness and correctness of the derived theoretical results.

  19. Personality and alcohol use: the role of impulsivity.

    Science.gov (United States)

    Shin, Sunny Hyucksun; Hong, Hyokyoung Grace; Jeon, Sae-Mi

    2012-01-01

    Research has shown that personality traits associated with impulsivity influence alcohol use during emerging adulthood, yet relatively few studies have examined how distinct facets of impulsivity are associated with alcohol use and abuse. We examine the influence of impulsivity traits on four patterns of alcohol use including frequency of alcohol use, alcohol-related problems, binge drinking, and alcohol use disorders (AUDs) in a community sample of young individuals (N=190). In multivariate regression analyses that controlled for peer and parental alcohol use, psychological distress, and developmental correlates (i.e., college, marriage, employment) in emerging adulthood, we found that urgency and sensation seeking were consistently related to all four constructs of alcohol use. The present study suggests that distinct impulsivity traits may play different roles in escalation of alcohol use and development of AUDs during emerging adulthood. PMID:21955874

  20. Generalized impulse response analysis: General or Extreme?

    Scientific Electronic Library Online (English)

    Hyeongwoo, Kim.

    2013-12-01

    Full Text Available Esta nota analiza la limitación de utilizar la función generalizada de impulso-respuesta (FGIR) de los modelos autoregresivos VAR (Pesaran y Shin, 1998). El FGIR es invariante al orden del rezago de las variables asociadas al modelo VAR . De hecho, el FGIR produce un conjunto de funciones respuestas [...] con base a supuestos de identificación extremos que se contradicen entre ellos, a menos que la matriz de covarianza sea diagonal. Con la ayuda de ejemplos empíricos, la presente nota demuestra que el FGIR puede generar inferencias incorrectas. Abstract in english This note discusses a pitfall of using the generalized impulse response function (GIRF) in vector autoregressive (VAR) models (Pesaran and Shin, 1998). The GIRF is general because it is invariant to the ordering of the variables in the VAR. The GIRF, in fact, is extreme because it yields a set of re [...] sponse functions that are based on extreme identifying assumptions that contradict each other, unless the covariance matrix is diagonal. With a help of empirical examples, the present note demonstrates that the GIRF may yield quite misleading economic inferences.

  1. 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

  2. Impulsive dynamic equations on a time scale

    Directory of Open Access Journals (Sweden)

    Youssef N. Raffoul

    2008-05-01

    Full Text Available Let $mathbb{T}$ be a time scale such that $0, t_i, T in mathbb{T}$, $i = 1, 2, dots, n$, and $0 < t_i < t_{i+1}$. Assume each $t_i$ is dense. Using a fixed point theorem due to Krasnosel'skii, we show that the impulsive dynamic equation $$displaylines{ y^{Delta}(t = -a(ty^{sigma}(t+ f ( t, y(t ,quad t in (0, T],cr y(0 = 0,cr y(t_i^+ = y(t_i^- + I (t_i, y(t_i , quad i = 1, 2, dots, n, }$$ where $y(t_i^pm = lim_{t o t_i^pm} y(t$, and $y^Delta$ is the $Delta$-derivative on $mathbb{T}$, has a solution. Under a slightly more stringent inequality we show that the solution is unique using the contraction mapping principle. Finally, with the aid of the contraction mapping principle we study the stability of the zero solution on an unbounded time scale.

  3. 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.

  4. MAC protocol design for impulse radio UWB based WPANs:

    OpenAIRE

    Shi, N; Yang, Y.; Niemegeers, I.G.

    2007-01-01

    Ultra Wide Band (UWB) has recently gained great interest for high data rate short-range WPANs. Designing a MAC protocol for UWB WPANs must take into account the physical layer characteristics. Due to large bandwidth and spreading spectrum, a time hopping impulse radio UWB (IR-UWB) system can accomplish multiple access by using code division multiplexing. Unlike most existing MAC protocols relying on contention access to limit transmissions, the MAC design for impulse radio intends to accommod...

  5. Impulsivity-like traits and smoking behavior in college students

    OpenAIRE

    Spillane, Nichea S.; Smith, Gregory T.; Kahler, Christopher W.

    2010-01-01

    Recent research has deconstructed the concept of impulsivity by identifying five different traits that influence engagement in impulsive behaviors: positive urgency (tendency to act rashly in response to a positive mood), negative urgency (tendency to act rashly in response to a negative mood), sensation seeking, lack of planning, and lack of perseverance. The traits are only moderately related to each other. The aim of this study was to apply this advance to the study of smoking. We tested a...

  6. INDIVIDUAL DIFFERENCES IN IMPULSIVE CHOICE AND TIMING IN RATS

    OpenAIRE

    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 of individual differences in a normal sample of hooded Lister rats. Three experiments utilized variations of a delay discounting task to measure th...

  7. Single-impulse magnetic focusing of launched cold atoms

    OpenAIRE

    Pritchard, M. J.; Arnold, A S; Smith, D.A.; Hughes, I. G.

    2005-01-01

    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...

  8. Internal ellipsoidal estimates of reachable set of impulsive control systems

    Energy Technology Data Exchange (ETDEWEB)

    Matviychuk, Oksana G. [Institute of Mathematics and Mechanics, Russian Academy of Sciences, 16 S. Kovalevskaya str., Ekaterinburg, 620990, Russia and Ural Federal University, 19 Mira str., Ekaterinburg, 620002 (Russian Federation)

    2014-11-18

    A problem of estimating reachable sets of linear impulsive control system with uncertainty in initial data is considered. The impulsive controls in the dynamical system belong to the intersection of a special cone with a generalized ellipsoid both taken in the space of functions of bounded variation. Assume that an ellipsoidal state constraints are imposed. The algorithms for constructing internal ellipsoidal estimates of reachable sets for such control systems and numerical simulation results are given.

  9. 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...

  10. A Step towards Distinction between Supervisory Impulsive and Strategic Abuse

    OpenAIRE

    Khan, Shahid N

    2014-01-01

    In this article, the researcher proposed a theoretical frame work of supervisory impulsive and strategic abuse. Sofor majority of the literature had focused on the supervisory impulsive abuse and its effects on employee’spersonal and/or professional life while the supervisory strategic abuse have enormously been ignored in theliterature. The theoretical frame work offered in this paper will help to identify the boundary line between thesetwo sub-types of abusive supervision. The researcher tr...

  11. Interactive effects of drinking history and impulsivity on college drinking

    OpenAIRE

    Adams, Zachary W.; Milich, Richard; Lynam, Donald R.; Charnigo, Richard J.

    2013-01-01

    The transition from adolescence into emerging adulthood is a critical developmental period for changes in alcohol use and drinking related problems. Prior research has identified a number of distinct developmental alcohol use trajectories, which appear to be differentially related to young adult drinking outcomes. Another correlate of alcohol use in early adulthood is impulsivity. The primary aim of this study was to examine the moderating role of impulsivity in the relation between patterns ...

  12. Social influences of competition on impulsive choices in domestic chicks

    OpenAIRE

    Amita, Hidetoshi; Kawamori, Ai; Matsushima, Toshiya

    2009-01-01

    Social factors involved in the control of impulsiveness were examined in domestic chicks. In binary choices between a large/long-delay option (LL) and a small/short-delay alternative (SS), chicks that had been competitively trained in groups of three individuals showed fewer choices of LL than did those trained in isolation (experiment 1), suggesting that competition causes impulsive choice. In experiment 2, in order to identify the critical factor involved, we tested the effects of perceived...

  13. Neural mechanisms of impulse control in sexually risky adolescents

    OpenAIRE

    Goldenberg, Diane; Telzer, Eva H.; 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...

  14. 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 ...

  15. Acoustic Radiation Force Impulse (ARFI) Imaging: a Review

    OpenAIRE

    Nightingale, Kathy

    2011-01-01

    Acoustic radiation force based elasticity imaging methods are under investigation by many groups. These methods differ from traditional ultrasonic elasticity imaging methods in that they do not require compression of the transducer, and are thus expected to be less operator dependent. Methods have been developed that utilize impulsive (i.e. < 1 ms), harmonic (pulsed), and steady state radiation force excitations. The work discussed herein utilizes impulsive methods, for which two imaging appr...

  16. Partial Equalization of Non-Minimum-Phase Impulse Responses

    OpenAIRE

    Daoud Berkani; Kale Izzet; Krukowski Artur; Maamar Ahfir

    2006-01-01

    We propose a modified version of the standard homomorphic method to design a minimum-phase inverse filter for non-minimum-phase impulse responses equalization. In the proposed approach some of the dominant poles of the filter transfer function are replaced by new ones before carrying out the inverse DFT. This method is useful when partial magnitude equalization is intended. Results for an impulse response measured in the car interior show that by using the modified version we can control the...

  17. Dynamic Systems Driven by Non-Poissonian Impulses

    DEFF Research Database (Denmark)

    Nielsen, Søren R.K.; Iwankiewicz, R.

    1997-01-01

    Dynamic systems under random trains of impulses driven by renewal point processes are studied. Then the system state variables no longer form a Markov vector as it is in the case of Poisson impulses. A general format is given for the replacing an ordinary renewal process by an equivalent Poisson process at the expense of the introduction of auxiliary state variables. A technique is devised for truncating the hierarchy of stochastic equations governing the auxiliary state variables. For the gener...

  18. Cue-Elicited Negative Affect in Impulsive Smokers

    OpenAIRE

    Doran, Neal; Cook, Jessica; McChargue, Dennis; Myers, Mark; Spring, Bonnie

    2008-01-01

    Impulsivity is associated with cigarette smoking, but the nature of this relationship and the mechanisms that maintain it are relatively unknown. The relationship has often been thought to reflect appetitive processes, but research suggests that an affective pathway exists as well. The present study tested the effect of impulsivity on affective responses to an environmental smoking cue. Adult smokers (N = 62) were exposed to a neutral cue and a smoking cue in separate experimental sessions in...

  19. IMPULSE NOISE REMOVAL FROM MAMMOGRAM IMAGES USING COMBINER APPROACH

    OpenAIRE

    I. Laurence Aroquiaraj

    2010-01-01

    Median filter is quite effective in recovering the images confounded by salt and pepper noise. It discards outliers (impulses) effectively, but it fails to provide adequate moothing for images corrupted with non-impulse noise. In this paper, two nonlinear techniques for image filtering, namely, New Filter I and New Filter II are proposed based on a nonlinear high-pass filter algorithm. New Filter I is constructed using a median filter, a highpass filter and a combiner. It suppresses uniform n...

  20. 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.

  1. A Systematic Review of Impulse Control Disorders in Parkinson's Disease

    DEFF Research Database (Denmark)

    Callesen, Mette Buhl; Scheel-Krüger, Jørgen; Kringelbach, Morten L.; Møller, Arne

    2013-01-01

    Throughout the past decade it has been recognized that dopaminergic medication administered to remedy motor symptoms in Parkinson's disease is associated with an enhanced risk for impulse control disorders and related compulsive behaviors such as hobbyism, punding, and the dopamine dysregulation syndrome. These complications are relatively frequent, affecting 6-15.5% of patients, and they most often appear, or worsen, after initiation of dopaminergic therapy or dosage increase. Recently, impulse...

  2. Determination of acoustical transfer functions using an impulse method

    Science.gov (United States)

    MacPherson, J.

    1985-02-01

    The Transfer Function of a system may be defined as the relationship of the output response to the input of a system. Whilst recent advances in digital processing systems have enabled Impulse Transfer Functions to be determined by computation of the Fast Fourier Transform, there has been little work done in applying these techniques to room acoustics. Acoustical Transfer Functions have been determined for auditoria, using an impulse method. The technique is based on the computation of the Fast Fourier Transform (FFT) of a non-ideal impulsive source, both at the source and at the receiver point. The Impulse Transfer Function (ITF) is obtained by dividing the FFT at the receiver position by the FFT of the source. This quantity is presented both as linear frequency scale plots and also as synthesized one-third octave band data. The technique enables a considerable quantity of data to be obtained from a small number of impulsive signals recorded in the field, thereby minimizing the time and effort required on site. As the characteristics of the source are taken into account in the calculation, the choice of impulsive source is non-critical. The digital analysis equipment required for the analysis is readily available commercially.

  3. 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.

  4. Two clusters of child molesters based on impulsiveness

    Scientific Electronic Library Online (English)

    Danilo A., Baltieri; Douglas P., Boer.

    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. Method [...] s: 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.

  5. Two clusters of child molesters based on impulsiveness

    Scientific Electronic Library Online (English)

    Danilo A., Baltieri; Douglas P., Boer.

    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. Method [...] s: 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.

  6. Impulse pressuring diffusion bonding of titanium alloy to stainless steel

    International Nuclear Information System (INIS)

    Impulse pressuring diffusion bonding between a titanium alloy TA17 and an austenitic stainless steel 0Cr18Ni9Ti has been carried out in vacuum. Relationships between the bonding parameters and the tensile strength of the joints were investigated, and the optimum bond parameters were obtained: bonding temperature T = 825 deg. C, maximum impulse pressure Pmax = 50 MPa, minimum impulse pressure Pmin = 8 MPa, number of impulses N = 30, impulse frequency f = 0.5 Hz. The maximum tensile strength of the joint was 321 MPa and the effective bonding time was only 180 s. The reaction products and the interface structure of the joints were investigated by optical microscopy, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and X-ray diffraction (XRD). The study revealed the existence of FeTi, Fe2Ti, ? phase and ?-Ti in the reaction zone. Brittle Fe-Ti intermetallic phases lower the strength and ductility of the impulse pressuring diffusion bonded couples significantly. This technique provides a reliable and efficient bonding method of titanium alloy and stainless steel

  7. Bounded and Periodic Solutions of Semilinear Impulsive Periodic System on Banach Spaces

    OpenAIRE

    Wei W; Chen Qian; Wang JinRong; Xiang X

    2008-01-01

    Abstract A class of semilinear impulsive periodic system on Banach spaces is considered. First, we introduce the -periodic PC-mild solution of semilinear impulsive periodic system. By virtue of Gronwall lemma with impulse, the estimate on the PC-mild solutions is derived. The continuity and compactness of the new constructed Poincaré operator determined by impulsive evolution operator corresponding to homogenous linear impulsive periodic system are shown. This allows us to apply Horn's ...

  8. 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

  9. Acoustic radiation force impulse of the liver

    Directory of Open Access Journals (Sweden)

    Mirko D’Onofrio

    2013-01-01

    Full Text Available 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.

  10. 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.

  11. 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%.

  12. 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

  13. 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

  14. 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".

  15. Impulsive control of single-mode laser chaotic system

    Science.gov (United States)

    Xu, Honglei

    2005-01-01

    In nonlinear optics, single mode laser is a typical example occurring self-organization phenomenon of bistability, oscillation and chaos. Stability analysis and stabilization problem in nonlinear optical systems are problems of great interest. With the development of control theory, impulsive control becomes more and more attractive. Impulsive control can describe some control process which can be used to control the population of a kind of insects by leaving its natural enemies at some proper instant and control the process of reaction by adding chemicals which instantaneously change state variables in a chemical reactor and so on. This paper studies the stabilization problem of single mode laser chaotic system via impulsive control. By using the method of Lyapunov functions, we derive some sufficient conditions for impulsive stabilization. These results are then applied to the single mode laser chaotic system. It is shown that by employing impulsive control method, all the solutions of this kind of chaotic system will converge to an equilibrium point. Finally, some numerical simulation is given to illustrate the efficiency of the obtained results.

  16. 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)

  17. Measuring long impulse responses with pseudorandom sequences and sweep signals

    DEFF Research Database (Denmark)

    Torras Rosell, Antoni Technical University of Denmark,

    2010-01-01

    In architectural acoustics, background noise, loudspeaker nonlinearities, and time variances are the most common disturbances that can compromise a measurement. The effects of such disturbances on measurement of long impulse responses with pseudorandom sequences (maximum-length sequences (MLS) and inverse repeated sequences (IRS)) and with linear and logarithmic sweep signals have been examined. The results reveal that the sweep method can provide a significant reduction of the effect of distortion compared with MLS/IRS techniques but, unlike what is claimed in the literature, sweep signals cannot reject all distortion artifacts from the causal part of the estimated impulse response. In all cases, an improvement of 3 dB in signal-to-noise ratio can be achieved if the measurement time is doubled either by averaging over two excitations or by doubling the length of the excitation signal. The time-frequency selectivity performed by the sweep technique is found to yield higher immunity to impulsive noise and timevariances.

  18. Can an "impulse response" really be defined for a photoreceiver?

    CERN Document Server

    Fraile-Pelaez, F Javier

    2015-01-01

    In this paper we examine the validity of the concept of impulse response employed to characterize the time response and the signal-to-noise ratio of p-i-n and similar photodetecting devices. We analyze critically the way in which the formalism of analog linear systems has been extrapolated, by employing results from macroscopic electromagnetic theory such as the Shockley--Ramo theorem or any equivalent approach, to the extreme case of a single-photon detection. We argue that the concept of "response to an optical impulse" is ill-defined in the customary terms it is envisioned in the literature, this is, as an output current pulse having a certain predictable, calculated temporal shape, in response to the detection of an optical "Dirac delta" impulse, conceived in turn as the absorption of a single photon.

  19. 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.

  20. Changes in metal properties after thermal and electric impulse processing

    Science.gov (United States)

    Shaburova, N. A.

    2015-04-01

    The results of the experiments on processing metal melts by powerful electromagnetic impulses are given. The generator used in the experiments has the following characteristics: pulse height - 10KV, duration - 1ns, leading edge - 0.1ns, repetition rate - 1KHz, the output - 100KWt. The duration of the processing is 10-15min. The comparative analysis of the processed and unprocessed samples results in the changes of structure, increase of density, solidity, plasticity and resilience of cast metal. The result analysis of different external physical processing methods on alloys shows full agreement with the results of the ultrasonic processing of metals. The hypothesis of ultrasonic shock wave formation at the pulse front was adopted as the main mechanism of the electromagnetic impulse impact on alloys. The theoretical part of the research describes the transformation process of electromagnetic impulses into acoustic ones.

  1. The development of impulsivity and suicidality in borderline personality disorder.

    Science.gov (United States)

    Paris, Joel

    2005-01-01

    Borderline personality disorder (BPD) is characterized by a broad pattern of impulsivity and suicidality. BPD usually begins in adolescence; the full clinical picture of the disorder is associated with developmental increases in impulsivity. However, BPD also has childhood precursors. The developmental pathways are similar to those found in other impulsive spectrum disorders, but children who later develop BPD probably have both externalizing and internalizing symptoms. Research in this area has made use of retrospective data from adults, prospective data from community studies, follow-up studies from children at risk, as well as research on "borderline pathology of childhood" (a condition with symptoms similar to adult BPD). Existing evidence suggests that both temperamental and environmental risk factors play a role in the development of the behavioral patterns associated with the disorder. These pathways also help account for the life course and outcome of BPD in adulthood. PMID:16613432

  2. 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)

  3. 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.

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

    Science.gov (United States)

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

    2015-10-01

    Although mouthguards are effective, inexpensive, easy to use, and readily available, this form of protective equipment has been underutilized. "Impulsive delay discounting" (an index of impulsive behavior) among high school athletes may help explain their decision making regarding use of protective equipment such as mouthguards. We investigated the relationship between high school baseball, softball, and basketball players' mouthguard use, impulsive delay discounting, and the precaution adoption process model (a behavior change theory). A convenience sample of boys' and girls' basketball and baseball/softball players at 21 high schools in the Greater Columbus, Ohio, metro area completed a self-administered survey that captured their demographic information, knowledge, attitudes, and beliefs regarding mouthguard use, impulsive delay discounting, and precaution adoption process model stage. We surveyed a total of 1636 students (55.9 % male, 43.8 % female, 0.3 % unknown). Only 12.3 % reported using a mouthguard either every time or sometimes during practice or competition. The primary reasons reported for not wearing mouthguards were they were not required to (65.3 %) and that the athletes could not breathe or talk while wearing one (61.5 %). These reasons were consistent across sex and sport. Most athletes reported that their coaches (87.3 %) and parents (64.5 %) had never talked to them about wearing a mouthguard. Lower precaution adoption process model stage was significantly associated with higher impulsivity (p softball remains low despite the risk of dental injury in these sports. Effective, evidence-based, targeted, and tailored interventions to improve adolescent athletes' use of mouthguards to prevent sports-related dental injuries should be based on the specific behavioral and social factors influencing each athlete's decision making regarding use of mouthguards. PMID:26391156

  5. Impulsive differential equations asymptotic properties of the solutions

    CERN Document Server

    Bainov, DD

    1995-01-01

    The question of the presence of various asymptotic properties of the solutions of ordinary differential equations arises when solving various practical problems. The investigation of these questions is still more important for impulsive differential equations which have a wider field of application than the ordinary ones.The results obtained by treating the asymptotic properties of the solutions of impulsive differential equations can be found in numerous separate articles. The systematized exposition of these results in a separate book will satisfy the growing interest in the problems related

  6. 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.

  7. 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.

  8. Partial Equalization of Non-Minimum-Phase Impulse Responses

    Directory of Open Access Journals (Sweden)

    Daoud Berkani

    2006-01-01

    Full Text Available We propose a modified version of the standard homomorphic method to design a minimum-phase inverse filter for non-minimum-phase impulse responses equalization. In the proposed approach some of the dominant poles of the filter transfer function are replaced by new ones before carrying out the inverse DFT. This method is useful when partial magnitude equalization is intended. Results for an impulse response measured in the car interior show that by using the modified version we can control the sound quality more precisely than when using the standard method.

  9. 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

  10. 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.

  11. 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…

  12. 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.

  13. 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...

  14. 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...

  15. 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 (...

  16. 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 (...

  17. Impulse control and its application in portfolio and hedging with both fixed and proportional transaction costs

    OpenAIRE

    A. Delavarkhalafi; Karbaschi, M.

    2014-01-01

    In this paper, we will state impulse control and its application in portfolio selection. For this purpose, we first introduce Quasi Variational Inequalities. Introducing impulse control, in stochastic stopping times we have jumps with stochastic size. Then by using approximative Markov chain, the optimal impulse control is obtained in portfolio, including European option. Finally, considering default parameters, the numerical results in optimal impulse control is obtained.

  18. Linear Impulsive Periodic System with Time-Varying Generating Operators on Banach Space

    OpenAIRE

    Wei W; Wang JinRong; Xiang X

    2007-01-01

    A class of the linear impulsive periodic system with time-varying generating operators on Banach space is considered. By constructing the impulsive evolution operator, the existence of -periodic -mild solution for homogeneous linear impulsive periodic system with time-varying generating operators is reduced to the existence of fixed point for a suitable operator. Further the alternative results on -periodic -mild solution for nonhomogeneous linear impulsive periodic system with time-varying ...

  19. 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...

  20. Right ventromedial prefrontal cortex: a neuroanatomical correlate of impulse control in boys

    OpenAIRE

    Boes, Aaron D; Bechara, Antoine; TRANEL, DANIEL; Anderson, Steve W.; Richman, Lynn; Nopoulos, Peg

    2008-01-01

    Emerging data on the neural mechanisms of impulse control highlight brain regions involved in emotion and decision making, including the ventromedial prefrontal cortex (vmPFC), anterior cingulate cortex (ACC) and amygdala. Variation in the development of these regions may influence one's propensity for impulsivity and, by extension, one's vulnerability to disorders involving low impulse control (e.g. substance abuse). Here we test the hypothesis that lower impulse control is associated with s...

  1. Complexity of an SIR epidemic dynamics model with impulsive vaccination control

    International Nuclear Information System (INIS)

    This paper considered an IR epidemic model with impulsive vaccination, which may inherently oscillate. We studied the impulsive control and get the conditions on which epidemic-elimination solution is globally asymptotically and the conditions of boundedness of system. On the other hand if the epidemic is turn out to be endemic, we studied numerically the influences of impulsive vaccination on the periodic oscillation of the system which is without impulsion and found phenomenon of chaos in this case

  2. 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.

  3. Impulse control in the dorsolateral prefrontal cortex counteracts post-diet weight regain in obesity.

    Science.gov (United States)

    Weygandt, Martin; Mai, Knut; Dommes, Esther; Ritter, Kerstin; Leupelt, Verena; Spranger, Joachim; Haynes, John-Dylan

    2015-04-01

    A variety of studies suggest that efficient treatments to induce short-term dietary success in obesity exist. However, sustained maintenance of reduced weight is rare as a large proportion of patients start to regain weight when treatment is discontinued. Thus, from a clinical perspective, it would be desirable to identify factors that counteract post-diet weight regain across longer time-scales. To address this question, we extended our previous work on neural impulse control mechanisms of short-term dietary success in obesity and now investigated the mechanisms counteracting long-term weight regain after a diet. Specifically, we measured neural impulse control during a delay discounting task with fMRI at two time points, i.e. the beginning ('T0') and the end ('T12') of a one-year follow-up interval after a 12-week diet. Then, we tested whether activity in the dorsolateral prefrontal cortex (DLPFC) at T0 and whether activity changes across the follow-up period (T0-T12) are linked to success in weight maintenance. The analyses conducted show that control-related DLPFC activity at T0 was coupled to the degree of success in weight maintenance. Consistently, also behavioral measures of control were linked to the degree of success in maintenance. A direct comparison of neural and behavioral control parameters for prognostic weight change modeling revealed that neural signals were more informative. Taken together, neural impulse control in the DLPFC measured with fMRI directly after a diet predicts real-world diet success in obese patients across extended time periods. PMID:25576647

  4. Impulsive, Agitated Behaviors May Be Warning Signs for Suicide

    Science.gov (United States)

    Impulsive, Agitated Behaviors May Be Warning Signs for Suicide New study of more than 2,800 people with depression might give clearer clues to state of mind, ... HealthDay . All rights reserved. More Health News on: Depression Mental Health Suicide Recent Health News

  5. 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 (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 (9 dpf) 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 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

  6. A Survey on Oscillation of Impulsive Ordinary Differential Equations

    Directory of Open Access Journals (Sweden)

    Fatma Karakoç

    2010-01-01

    Full Text Available This paper summarizes a series of results on the oscillation of impulsive ordinary differential equations. We consider linear, half-linear, super-half-linear, and nonlinear equations. Several oscillation criteria are given. The Sturmian comparison theory for linear and half linear equations is also included.

  7. Brain structure correlates of emotion-based rash impulsivity.

    Science.gov (United States)

    Muhlert, N; Lawrence, A D

    2015-07-15

    Negative urgency (the tendency to engage in rash, ill-considered action in response to intense negative emotions), is a personality trait that has been linked to problematic involvement in several risky and impulsive behaviours, and to various forms of disinhibitory psychopathology, but its neurobiological correlates are poorly understood. Here, we explored whether inter-individual variation in levels of trait negative urgency was associated with inter-individual variation in regional grey matter volumes. Using voxel-based morphometry (VBM) in a sample (n=152) of healthy participants, we found that smaller volumes of the dorsomedial prefrontal cortex and right temporal pole, regions previously linked to emotion appraisal, emotion regulation and emotion-based decision-making, were associated with higher levels of trait negative urgency. When controlling for other impulsivity linked personality traits (sensation seeking, lack of planning/perseverance) and negative emotionality per se (neuroticism), these associations remained, and an additional relationship was found between higher levels of trait negative urgency and smaller volumes of the left ventral striatum. This latter finding mirrors recent VBM findings in an animal model of impulsivity. Our findings offer novel insight into the brain structure correlates of one key source of inter-individual differences in impulsivity. PMID:25957991

  8. 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

  9. Laboratory paradigms of impulsivity and alcohol dependence: a review.

    Science.gov (United States)

    Aragues, M; Jurado, R; Quinto, R; Rubio, G

    2011-01-01

    Impulsivity can be defined as choosing a smaller, immediate reward over a larger, delayed reward. From this perspective, addictive behaviors such as substance abuse and pathological gambling reflect a series of impulsive choices. However, impulsivity is not a homogeneous construct. Laboratory measures of impulsivity reflect two types of processes. The first is related to behavioral inhibition and refers to an individual's ability to appropriately inhibit thoughts or actions. The second is the delay of reward dimension, namely the degree to which immediate (rewarding) consequences have more control over an individual's behavior than consequences that are delayed. In this review, we describe how alcohol is associated with significant impairments in these paradigms. We also suggest that they may have a role in the development of alcohol dependence. These results are in agreement with a model in which delay of gratification might be a marker for early use and/or abuse of alcohol, whereas impairment in behavioral inhibition might be a marker for maintained use in time and, therefore, for progression towards alcohol dependence. PMID:21150205

  10. 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.

  11. Almost Periodic Solutions for Impulsive Fractional Stochastic Evolution Equations

    OpenAIRE

    Toufik Guendouzi; Lamia Bousmaha

    2014-01-01

    In this paper, we consider the existence of square-mean piecewise almost periodic solutions for impulsive fractional stochastic evolution equations involving Caputo fractional derivative. The main results are obtained by means of the theory of operators semi-group, fractional calculus, fixed point technique and stochastic analysis theory and methods adopted directly from deterministic fractional equations. Some known results are improved and generalized.

  12. Dimensions of impulsive behavior and treatment outcomes for adolescent smokers.

    Science.gov (United States)

    Harris, Millie; Penfold, Robert B; Hawkins, Ariane; Maccombs, Jared; Wallace, Bryan; Reynolds, Brady

    2014-02-01

    Adolescent cigarette smoking rates remain a significant public health concern, and as a result there is a continued need to understand factors that contribute to an adolescent's ability to reduce or quit smoking. Previous research suggests that impulsive behavior may be associated with treatment outcomes for smoking. The current research (N = 81) explored 3 dimensions of impulsive behavior as predictors of treatment response from a social-cognitive type program for adolescent smokers (i.e., Not On Tobacco; N-O-T). Measures included laboratory assessments of delay discounting, sustained attention, and behavioral disinhibition. A self-report measure of impulsivity was also included. Adolescent smokers who had better sustained attention were more likely to reduce or quit smoking by the end of treatment. No other measures of impulsivity were significantly associated with treatment response. From these findings, an adolescent smoker's ability to sustain attention appears to be an important behavioral attribute to consider when implementing smoking cessation programs such as N-O-T. PMID:24417209

  13. Impaired goal-directed behavioural control in human impulsivity

    OpenAIRE

    Hogarth, Lee; Chase, Henry W.; Baess, Kathleen

    2010-01-01

    Two dissociable learning processes underlie instrumental behaviour. Whereas goal-directed behaviour is controlled by knowledge of the consequences, habitual behaviour is elicited directly by antecedent Pavlovian stimuli without knowledge of the consequences. Predominance of habitual control is thought to underlie psychopathological conditions associated with corticostriatal abnormalities, such as impulsivity and drug dependence. To explore this claim, smokers were assessed for nicotine depend...

  14. The Impulse toward Comedy in Margaret Atwood's Poetry.

    Science.gov (United States)

    Benton, Carol L.

    The impulse toward comedy in the poetry of Canadian author Margaret Atwood occurs as a by-product of an interaction between scripted text and performing reader. Reading, then, may be profitably viewed as a rehearsal for both. In the classroom, this stylistic approach to Atwood's poetry can be emphasized over thematic analysis. In her poetry,…

  15. The Chaotification of Discrete Hopfield Neural Networks via Impulsive Control

    International Nuclear Information System (INIS)

    The chaotification of discrete Hopfield neural networks is studied with impulsive control techniques. No matter whether the original systems are stable or not, chaotification theorems for discrete Hopfield neural networks are derived, respectively. Finally, the effectiveness of the theoretical results is illustrated by some numerical examples. (general)

  16. Periodic components of hand acceleration/deceleration impulses during telemanipulation

    Energy Technology Data Exchange (ETDEWEB)

    Draper, J.V. [Oak Ridge National Lab., TN (United States); Handel, S. [Tennessee Univ., Knoxville, TN (United States). Dept. of Psychology

    1994-01-01

    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.

  17. Targeting impulsivity in Parkinson’s disease using atomoxetine

    OpenAIRE

    Kehagia, Angie A.; Housden, Charlotte R; Regenthal, Ralf; Barker, Roger A.; Müller, Ulrich; Rowe, James; SAHAKIAN, BARBARA J.; Robbins, Trevor W.

    2014-01-01

    In a double-blind randomized placebo-controlled study, Kehagia et al. investigate the effects of a single dose of atomoxetine, a selective noradrenaline reuptake inhibitor, in 25 patients with Parkinson’s disease. Consistent with the presence of a longstanding noradrenergic deficit, atomoxetine improved stopping accuracy, and reduced reflection impulsivity during decision making.

  18. An update on impulse control disorders in Parkinson's disease

    OpenAIRE

    V. VOON; Mehta, AR

    2012-01-01

    The impulse control disorders associated with dopaminergic medication in Parkinson's disease provide a clear and unequivocal demonstration of the biological basis of behavioural addiction. These behaviours can be dramatic, resulting in significant financial and social consequences, with functional impairments, and include pathological gambling, compulsive shopping, hypersexuality, binge eating, punding (complex prolonged, purposeless, and stereotyped behaviour) and compulsive medication use. ...

  19. Simplified transient model of the transformer during impulse test

    Energy Technology Data Exchange (ETDEWEB)

    Al-Ammar, E.; Karady, G.G. [Arizona State Univ., Tempe, AZ (United States). Dept. of Electrical Engineering

    2007-07-01

    The challenge of accurately modelling transformers within a power system was discussed with particular reference to transformer windings. The difficulty lies in the fact that transformers have a large number of core designs and their many parameters are both nonlinear and frequency dependent. A complete model of a transformer would require that every turn be represented and that all mutual couplings, inductive and capacitive, be included with every other turn. Transformer windings are exposed to various short duration impulse voltages of high amplitude produced by lightning or switching transients, and by insulator flashover. As such, winding insulation is one of the most important constructional elements of a transformer. Any weakness in insulation may cause transformer failure. A sensitive standard impulse test was performed in this study in order to verify the integrity of transformer insulation. High frequency transformer models from the literature were reviewed, and a simplified transient model was then proposed for a transformer operating during an impulse test via full wave impulse. The model parameters were identified. The simulation results from the Electromagnetic Transients Program (EMTP) were found to be in approximate agreement with the 25 kVA distribution transformer experimental results. 32 refs., 8 figs.

  20. Impulsive synchronization of two nonidentical chaotic systems with time-varying delay

    International Nuclear Information System (INIS)

    This Letter investigates synchronization of two nonidentical Lur'e systems with time-varying delay and parameter mismatches via impulsive control. Based on the theory of impulsive functional differential equations, sufficient conditions for impulsive synchronization with a bound on the synchronization error are derived. An illustrative example is provided to validate the proposed method.

  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. Dimensions of Impulsivity and Aggression Associated with Suicide Attempts Among Bipolar Patients: A Preliminary Study

    Science.gov (United States)

    Michaelis, Benjamin H.; Goldberg, Joseph F.; Davis, Glen P.; Singer, Tara M.; Garno, Jessica L.; Wenze, Susan J.

    2004-01-01

    Impulsivity and hostility are often thought to be interrelated among depressed patients with suicidal behavior, but few studies have examined this relationship empirically. In this study, we assessed trait impulsivity and hostility among 52 DSM-IV bipolar subjects with and without histories of suicide attempts. Impulsivity and hostility were…

  3. Selective excitation of spin resonance in orthoferrite PrFeO3 with impulsive polarized terahertz radiation

    International Nuclear Information System (INIS)

    Single cycle terahertz (THz) pulses were employed to excite coherent spin waves in (110)-oriented PrFeO3 single crystal. The free induction decay radiations at frequency of 0.34?THz (quasi-ferromagnetic mode, FM mode) and 0.41 THz (quasi-antiferromagnetic mode, AFM mode) were observed arising from the coupling of magnetic moment with the impulsive magnetic field of polarized terahertz radiation. These two spin modes in PrFeO3 can be excited and modulated by the magnetic field of THz pulse with a specific polarization with respect to the crystal axis. The extracted complex dielectric permittivity and magnetic permeability dispersion in THz range suggest a higher efficiency of energy transfer from the impulsive THz pulse into the AFM than the FM spin system

  4. Selective excitation of spin resonance in orthoferrite PrFeO{sub 3} with impulsive polarized terahertz radiation

    Energy Technology Data Exchange (ETDEWEB)

    Song, Gaibei; Jiang, Junjie; Wang, Xinyan; Jin, Zuanming; Lin, Xian; Ma, Guohong, E-mail: ghma@staff.shu.edu.cn, E-mail: sxcao@shu.edu.cn; Cao, Shixun, E-mail: ghma@staff.shu.edu.cn, E-mail: sxcao@shu.edu.cn [Department of Physics, Shanghai University, Shanghai 200444 (China)

    2013-12-28

    Single cycle terahertz (THz) pulses were employed to excite coherent spin waves in (110)-oriented PrFeO{sub 3} single crystal. The free induction decay radiations at frequency of 0.34?THz (quasi-ferromagnetic mode, FM mode) and 0.41 THz (quasi-antiferromagnetic mode, AFM mode) were observed arising from the coupling of magnetic moment with the impulsive magnetic field of polarized terahertz radiation. These two spin modes in PrFeO{sub 3} can be excited and modulated by the magnetic field of THz pulse with a specific polarization with respect to the crystal axis. The extracted complex dielectric permittivity and magnetic permeability dispersion in THz range suggest a higher efficiency of energy transfer from the impulsive THz pulse into the AFM than the FM spin system.

  5. Isolating the delay component of impulsive choice in adolescent rats

    Directory of Open Access Journals (Sweden)

    h n r

    2014-01-01

    Full Text Available Impulsive choice — the preference for small immediate rewards over larger delayed rewards — has been linked to various psychological conditions ranging from behavioral disorders to addiction. These links highlight the critical need to dissect the various components of this multifaceted behavioral trait. Delay discounting tasks allow researchers to study an important factor of this behavior: how the subjective value of a rewards changes over a delay period. However, existing methods of delay discounting include a confound of modifying reward sizes during the procedure. Here we present a new approach of using a single constant reward size to assess delay discounting. A complementary approach could hold delay constant and assess the utility of changing quantities of a reward. Isolating these behavioral components can advance our ability to explore the behavioral complexity of impulsive choice. We present the methods for isolating delay in detail, and further capitalize on this method by pairing it with a standard peak interval task to test whether individual variation in delay discounting can be explained by differences in perception of time in male and female adolescent rats. We find that rats that were more precise in discriminating time intervals were also less impulsive in their choice. Our data suggest that differences in timing and delay discounting are not causally related, but instead are more likely influenced by a common factor. Further, the mean-level change in our measure between postnatal day 28 and 42 suggests this test may be capturing a developmental change in this factor. In summary, this new method of isolating individual components of impulsive choice (delay or quantity can be efficiently applied in either adolescent or adult animal models and may help elucidate the mechanisms underlying impulsivity and its links to psychological disorders.

  6. 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

  7. Global asymptotic stability analysis of bidirectional associative memory neural networks with distributed delays and impulse

    International Nuclear Information System (INIS)

    Many systems existing in physics, chemistry, biology, engineering and information science can be characterized by impulsive dynamics caused by abrupt jumps at certain instants during the process. These complex dynamical behaviors can be model by impulsive differential system or impulsive neural networks. This paper formulates and studies a new model of impulsive bidirectional associative memory (BAM) networks with finite distributed delays. Several fundamental issues, such as global asymptotic stability and existence and uniqueness of such BAM neural networks with impulse and distributed delays, are established

  8. Robust stability of stochastic fuzzy delayed neural networks with impulsive time window.

    Science.gov (United States)

    Wang, Xin; Yu, Junzhi; Li, Chuandong; Wang, Hui; Huang, Tingwen; Huang, Junjian

    2015-07-01

    The urgent problem of impulsive moments which cannot be determined in advance brings new challenges beyond the conventional impulsive systems theory. In order to solve this problem, the novel concept of impulsive time window is proposed in this paper. And the stability problem of stochastic fuzzy uncertain delayed neural networks with impulsive time window is investigated. By combining the discretized Lyapunov function approach with mathematical induction method, several novel and easy-to-check sufficient conditions concerning the impulsive time window are derived to ensure that the model considered here is exponentially stable in mean square. Numerical simulations are presented to further demonstrate the effectiveness of the proposed stability criterion. PMID:25897509

  9. Direct measurement of the impulse in a magnetic thrust chamber system for laser fusion rocket

    Energy Technology Data Exchange (ETDEWEB)

    Maeno, Akihiro; Yamamoto, Naoji; Nakashima, Hideki [Interdisciplinary Graduate School of Engineering Science, Kyushu University, 6-1 Kasuga-kouen, Kasuga, Fukuoka 816-8580 (Japan); Fujioka, Shinsuke; Johzaki, Tomoyuki [Institute of Laser Engineering, Osaka University, Suita, Osaka 565-087 (Japan); Mori, Yoshitaka [Graduate School for the Creation of New Photonics Industries, Hamamatsu, Shizuoka 431-1202 (Japan); Sunahara, Atsushi [Institute for Laser Technology, Suita, Osaka 565-087 (Japan)

    2011-08-15

    An experiment is conducted to measure an impulse for demonstrating a magnetic thrust chamber system for laser fusion rocket. The impulse is produced by the interaction between plasma and magnetic field. In the experiment, the system consists of plasma and neodymium permanent magnets. The plasma is created by a single-beam laser aiming at a polystyrene spherical target. The impulse is 1.5 to 2.2 {mu}Ns by means of a pendulum thrust stand, when the laser energy is 0.7 J. Without magnetic field, the measured impulse is found to be zero. These results indicate that the system for generating impulse is working.

  10. The impact of craving and impulsivity on aggression in detoxified cocaine-dependent patients.

    Science.gov (United States)

    Roozen, Hendrik G; van der Kroft, Petra; van Marle, Hjalmar J; Franken, Ingmar H A

    2011-06-01

    Patients with substance use disorders are frequently associated with impulsivity that may underlie elevated levels life-threatening types of behavior, including aggression. In addition, craving is a prominent feature of addiction and appears to be closely related to impulsivity. This study assessed the unique contribution of cocaine craving and impulsivity in predicting aggression by means of correlational and mediational analyses. Forty inpatient detoxified cocaine-dependent patients and 40 matched healthy controls were enrolled. These participants filled out the Obsessive Compulsive Drug Use Scale, the Dickman Impulsivity Inventory, and the Aggression Questionnaire. The patient group showed elevated levels of impulsivity and aggression as compared with the control group. Although cocaine craving is positively correlated with both impulsivity and aggression, craving did not mediate the relationship between both constructs. It is concluded that craving does not have an impact on the relationship between impulsivity and trait aggression in this patient sample. PMID:21315541

  11. Hybrid optimization for multiple-impulse reconfiguration trajectories of satellite formation flying

    Science.gov (United States)

    Kim, Dong-Yoon; Woo, Byoungsam; Park, Sang-Young; Choi, Kyu-Hong

    2009-12-01

    A hybrid optimization method is developed for fuel-optimal reconfigurations of a group of satellites flying in formation. The genetic algorithm performs a global search to find two-impulse trajectories, and primer vector analysis finds multiple-impulsive local optimal trajectories with the two-impulse trajectories as initial guesses. Hybrid optimization finds globally optimal trajectories for formation reconfigurations, including formation resizing, reassignment and reorientation maneuvers. Multiple-impulse trajectories reduce the fuel consumption from the two-impulse trajectories by up to 4.4% for those maneuvers. In real missions, satellites can follow two-impulse trajectories to gain the advantage of a smaller number of impulses, with the cost of slightly more propellant. The qualitative characteristics of the optimal trajectories are analyzed from the number of optimal trajectories found by hybrid optimization.

  12. Impulsivity components measured by the Brazilian version of the Barratt Impulsiveness Scale (BIS-11) / Componentes da impulsividade avaliados pela versão brasileira da Barratt Impulsiveness Scale (BIS-11)

    Scientific Electronic Library Online (English)

    Alina Gomide, Vasconcelos; Maycoln Leôni Martins, Teodoro; Leandro, Malloy-Diniz; Humberto, Correa.

    2015-03-01

    Full Text Available O objetivo principal desse estudo foi investigar as características psicométricas da Barratt Impulsiveness Scale (BIS-11). A análise do conteúdo 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 presença de [...] sintomas de Transtorno Mental Comum e TDAH, uso de álcool e tabagismo. A idade média foi de 27,32 (DP=8,69) anos, 56% eram mulheres e 52% tinham educação superior incompleta. Análises de conteúdo e fatorial indicaram que a impulsividade é representada mais adequadamente por dois fatores denominados dificuldade de planejamento e controle inibitório. Concordância teste-reteste indicou que os escores se mantiveram estáveis após sete meses. Adicionalmente, os escores da BIS-11 discriminaram os indivíduos em termos de tabagismo e sintomas psicopatológicos, indicando evidências de validade de critério. A discussão dos resultados foi baseada no modelo neuropsicológico dos componentes quentes e frios das funções 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.

  13. The impulsive and gradual phases of a solar limb flare as observed from the solar maximum mission satellite

    International Nuclear Information System (INIS)

    Simultaneous observations of a solar limb flare in the X-ray and ultraviolet regions of the spectrum are presented. Temporal and spectral X-ray observations were obtained for the 25-300 keV range while temporal, spectral, and spatial X-ray observations were obtained for the 30-0.3 keV range. The ultraviolet observations were images with a 10'' spatial resolution in the lines of O v (Tsub(e) approx. equal to 2.5 x 105 K) and Fe XXI (Tsub(e) approx. equal to 1.1 x 107 K). The hard X-ray and O v data indicate that the impulsive phase began in the photosphere or chromosphere and continued for several minutes as material was ejected into the corona. Impulsive excitation was observed up to 30,000 km above the solar surface at specific points in the flare loop. The Fe XXI observations indicate a preheating before the impulsive phase and showed the formation of hot post-flare loops. This later formation was confirmed by soft X-ray observations. These observations provide limitations for current flare models and will provide the data needed for initial conditions in modeling the concurrent coronal transient. (orig.)

  14. Video game therapy for emotional regulation and impulsivity control in a series of treated cases with bulimia nervosa.

    Science.gov (United States)

    Fagundo, Ana B; Santamaría, Juan J; Forcano, Laura; Giner-Bartolomé, Cristina; Jiménez-Murcia, Susana; Sánchez, Isabel; Granero, Roser; Ben-Moussa, Maher; Magnenat-Thalmann, Nadia; Konstantas, Dimitri; Lam, Tony; Lucas, Mikkel; Nielsen, Jeppe; Bults, Richard G A; Tarrega, Salomé; Menchón, José M; de la Torre, Rafael; Cardi, Valentina; Treasure, Janet; Fernández-Aranda, Fernando

    2013-11-01

    Although standard psychological treatments have been successful in treating several core features in eating disorders (ED), other characteristics such as emotional regulation or impulsivity appear to be more resistant to change. There is a growing body of evidence to support the efficacy of cognitive remediation for cognitive and emotional difficulties in ED. Playmancer/ Islands is a video game (VG) designed to specifically treat mental disorders, characterized by problems in impulse control. The objective of the game is to increase self-control over emotions, decision making and behaviours. The aim of this study is to describe the results from a consecutive series of nine bulimia nervosa patients who were treated with the VG in addition to cognitive behaviour therapy (CBT). The outcomes included clinical and psychopathological questionnaires, and physiological measures were obtained during the VG. Emotional regulation improved, heart rate variability increased, and respiratory rate and impulsivity measures reduced after the treatment. These findings suggest that VG training may enhance treatment for ED. PMID:24092598

  15. Impulsive delayed reward discounting as a genetically-influenced target for drug abuse prevention: a critical evaluation

    Science.gov (United States)

    Gray, Joshua C.; MacKillop, James

    2015-01-01

    This review evaluates the viability of delayed reward discounting (DRD), an index of how much an individual devalues a future reward based on its delay in time, for genetically-informed drug abuse prevention. A review of the literature suggests that impulsive DRD is robustly associated with drug addiction and meets most of the criteria for being an endophenotype, albeit with mixed findings for specific molecular genetic influences. Several modes of experimental manipulation have been demonstrated to reduce DRD acutely. These include behavioral strategies, such as mindfulness, reward bundling, and episodic future thinking; pharmacological interventions, including noradrenergic agonists, adrenergic agonists, and multiple monoamine agonists; and neuromodulatory interventions, such as transcranial magnetic stimulation and transcranial direct current stimulation. However, the generalization of these interventions to positive clinical outcomes remains unclear and no studies to date have examined interventions on DRD in the context of prevention. Collectively, these findings suggest it would be premature to target DRD for genetically-informed prevention. Indeed, given the evidence of environmental contributions to impulsive DRD, whether genetically-informed secondary prevention would ever be warranted is debatable. Progress in identifying polymorphisms associated with DRD profiles could further clarify the underlying biological systems for pharmacological and neuromodulatory interventions, and, as a qualitatively different risk factor from existing prevention programs, impulsive DRD is worthy of investigation at a more general level as a novel and promising drug abuse prevention target. PMID:26388788

  16. Fuzzy Impulsive Control of Permanent Magnet Synchronous Motors

    International Nuclear Information System (INIS)

    The permanent magnet synchronous motors (PMSMs) may experience chaotic behaviours with systemic parameters falling into a certain area or under certain working conditions, which threaten the secure and stable operation of motor-driven. Hence, it is important to study the methods of controlling or suppressing chaos in PMSMs. In this work, the Takagi–Sugeno (T-S) fuzzy impulsive control model for PMSMs is established via the T-S modelling methodology and impulsive technology. Based on the new model, the control conditions of asymptotical stability and exponential stability for PMSMs have been derived by the Lyapunov method. Finally, an illustrated example is also given to show the effectiveness of the obtained results

  17. Impulsive Spot Heating and Thermal Explosion of Interstellar Grains Revisited

    CERN Document Server

    Ivlev, A V; Vasyunin, A; Caselli, P

    2015-01-01

    The problem of impulsive heating of dust grains in cold, dense interstellar clouds is revisited theoretically, with the aim to better understand leading mechanisms of the explosive desorption of icy mantles. It is rigorously shown that if the heating of a reactive medium occurs within a sufficiently localized spot (e.g., heating of mantles by cosmic rays), then the subsequent thermal evolution is characterized by a single dimensionless number $\\lambda$. This number identifies a bifurcation between two distinct regimes: When $\\lambda$ exceeds a critical value (threshold), the heat equation exhibits the explosive solution, i.e., the thermal (chemical) explosion is triggered. Otherwise, thermal diffusion causes the deposited heat to spread over the entire grain -- this regime is commonly known as the whole-grain heating. The theory allows us to find a critical combination of the physical parameters that govern the explosion of icy mantles due to impulsive spot heating. In particular, the calculations suggest tha...

  18. Idiopathic Basal Ganglia Calcification Presented with Impulse Control Disorder.

    Science.gov (United States)

    Sahin, Cem; Levent, Mustafa; Akbaba, Gulhan; Kara, Bilge; Yeniceri, Emine Nese; Inanc, Betul Battaloglu

    2015-01-01

    Primary familial brain calcification (PFBC), also referred to as Idiopathic Basal Ganglia Calcification (IBGC) or "Fahr's disease," is a clinical condition characterized by symmetric and bilateral calcification of globus pallidus and also basal ganglions, cerebellar nuclei, and other deep cortical structures. It could be accompanied by parathyroid disorder and other metabolic disturbances. The clinical features are dysfunction of the calcified anatomic localization. IBGC most commonly presents with mental damage, convulsion, parkinson-like clinical picture, and neuropsychiatric behavior disorders; however, presentation with impulse control disorder is not a frequent presentation. In the current report, a 43-year-old male patient who has been admitted to psychiatry policlinic with the complaints of aggressive behavior episodes and who has been diagnosed with impulse control disorder and IBGC was evaluated in the light of the literature. PMID:26246920

  19. An impulse radar array for detecting land mines

    Energy Technology Data Exchange (ETDEWEB)

    Gavel, D.T.; Mast, J.E.; Warhus, J.; Azevedo, S.G.

    1995-04-03

    The Lawrence Livermore National Laboratory has developed radar and imaging technologies with potential application in demining efforts. A patented wideband (impulse) radar that is very compact, very low cost, and very low power, has been demonstrated in test fields to be able to detect and image nonmetallic land mines buried in 2-10 cm of soil. The scheme takes advantage of the very short radar impulses and the ability to form a large synthetic aperture with many small individual units, to generate high resolution 2-D or 3-D tomographic images of the mine and surrounding ground. Radar range calculations predict that a vehicle-mounted or man-carried system is quite feasible using this technology. This paper presents the results of field tests using a prototype unit and describes practical mine detection system concepts. Predicted capabilities in terms of stand-off range and radiated power requirements are discussed.

  20. Develop of a generator of current impulses with floating electrodes

    International Nuclear Information System (INIS)

    Under very defined conditions, the floating electrodes have the property of generating repetitive current impulses and of constant energy, which can have diverse electric applications. One of these applications is described in this paper: The construction of a prototype generates of repetitive impulses of current, of constant energy, with floating electrodes. In the design it was defined the available energy for the discharge starting from the capacity of the floating electrode. The distances inter-electrodes they were obtained starting from the field's electric disruptive. Once it determines two the electric parameters; the generator were modeled with the program A TP/EMTP. In this article the results of the modeling and the obtained mensurations of the currents are presented and the generator prototype

  1. DETECTION OF LANDMINES USING IMPULSE GROUND PENETRATING RADAR

    OpenAIRE

    RAMAKRISHNA PORANDLA; PODILI RAMU; GELLA RAVIKANTH

    2013-01-01

    Landmines are affecting the lives and livelihood of millions of people around the world. In this paper, we presentThe video impulse ground penetrating radar system for detection for small and shallow buried objects has been developed. The hardware combines commercially available components with components specially developed or modified for being used in the system. The GPR system has been desired to measure accurately electromagnetic field backscattered from subsurface targets in order to al...

  2. Protocols for Impulse Radio UWB Ad Hoc Networks :

    OpenAIRE

    Shi, N

    2010-01-01

    Ultra Wideband (UWB) technology offers an unprecedented opportunity to further accelerate the evolution of wireless communication and expand the application landscape by enabling outstanding capabilities. UWB radio is fundamentally different from most radio technologies, e.g., Bluetooth, WLAN, etc. UWB has many forms. A promising but, not well explored form is single-band impulse radio UWB (IR-UWB). In IR-UWB data is transmitted by using a series of very narrow pulses rather than by modulatin...

  3. Impulse Turbine Efficiency Calculation Methods with Organic Rankine Cycle

    OpenAIRE

    Dahlqvist, Johan

    2012-01-01

    A turbine was investigated by various methods of calculating its efficiency. The project was based on an existing impulse turbine, a one-stage turbine set in an organic Rankine cycle with the working fluid being R245fa. Various methods of loss calculation were explored in the search for a method sufficiently accurate to make valid assumptions regarding the turbine performance, while simple enough to be time efficient for use in industrial research and development.  The calculations were prima...

  4. Cavitation and bubble dynamics: the Kelvin impulse and its applications.

    Science.gov (United States)

    Blake, John R; Leppinen, David M; Wang, Qianxi

    2015-10-01

    Cavitation and bubble dynamics have a wide range of practical applications in a range of disciplines, including hydraulic, mechanical and naval engineering, oil exploration, clinical medicine and sonochemistry. However, this paper focuses on how a fundamental concept, the Kelvin impulse, can provide practical insights into engineering and industrial design problems. The pathway is provided through physical insight, idealized experiments and enhancing the accuracy and interpretation of the computation. In 1966, Benjamin and Ellis made a number of important statements relating to the use of the Kelvin impulse in cavitation and bubble dynamics, one of these being 'One should always reason in terms of the Kelvin impulse, not in terms of the fluid momentum…'. We revisit part of this paper, developing the Kelvin impulse from first principles, using it, not only as a check on advanced computations (for which it was first used!), but also to provide greater physical insights into cavitation bubble dynamics near boundaries (rigid, potential free surface, two-fluid interface, flexible surface and axisymmetric stagnation point flow) and to provide predictions on different types of bubble collapse behaviour, later compared against experiments. The paper concludes with two recent studies involving (i) the direction of the jet formation in a cavitation bubble close to a rigid boundary in the presence of high-intensity ultrasound propagated parallel to the surface and (ii) the study of a 'paradigm bubble model' for the collapse of a translating spherical bubble, sometimes leading to a constant velocity high-speed jet, known as the Longuet-Higgins jet. PMID:26442141

  5. Double-impulse magnetic focusing of launched cold atoms

    OpenAIRE

    Arnold, A S; Pritchard, M. J.; Smith, D.A.; Hughes, I. G.

    2005-01-01

    We have theoretically investigated three-dimensional 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. The performance of the two possible pulse sequences are compared and found to be ideal for loading both 'pancake' and 'sausage' shaped magnetic/optical microtraps. It is shown that focusing aberrations are considerably smaller for double-impulse magnetic lenses c...

  6. Subtyping pathological gamblers based on impulsivity, depression and anxiety

    OpenAIRE

    Ledgerwood, David M; Petry, Nancy M.

    2010-01-01

    This study examined putative subtypes of pathological gamblers (PGs) based on the Pathways Model, and it also evaluated whether the subtypes would benefit differentially from treatment. Treatment-seeking PGs (N = 229) were categorized into Pathways subtypes based on scores from questionnaires assessing anxiety, depression and impulsivity. The Addiction Severity Index Gambling assessed severity of gambling problems at baseline, post-treatment and 12-month follow-up. Compared with Behaviorally ...

  7. Robust Consensus in the Presence of Impulsive Channel Noise

    OpenAIRE

    Dasarathan, Sivaraman; Tepedelenlioglu, Cihan; Banavar, Mahesh; Spanias, Andreas

    2014-01-01

    A distributed average consensus algorithm robust to a wide range of impulsive channel noise distributions is proposed. This work is the first of its kind in the literature to propose a consensus algorithm which relaxes the requirement of finite moments on the communication noise. It is shown that the nodes reach consensus asymptotically to a finite random variable whose expectation is the desired sample average of the initial observations with a variance that depends on the ...

  8. Response Due To Impulsive Force In Generalized Thermomicrostretch Elastic Solid

    Science.gov (United States)

    Kumar, V.; Singh, R.

    2015-08-01

    A two dimensional Cartesian model of a generalized thermo-microstretch elastic solid subjected to impulsive force has been studied. The eigen value approach is employed after applying the Laplace and Fourier transforms on the field equations for L-S and G-L model of the plain strain problem. The integral transforms have been inverted into physical domain numerically and components of normal displacement, normal force stress, couple stress and microstress have been illustrated graphically.

  9. Almost Periodic Solutions for Impulsive Fractional Stochastic Evolution Equations

    Directory of Open Access Journals (Sweden)

    Toufik Guendouzi

    2014-08-01

    Full Text Available In this paper, we consider the existence of square-mean piecewise almost periodic solutions for impulsive fractional stochastic evolution equations involving Caputo fractional derivative. The main results are obtained by means of the theory of operators semi-group, fractional calculus, fixed point technique and stochastic analysis theory and methods adopted directly from deterministic fractional equations. Some known results are improved and generalized.

  10. Stage-Structured Impulsive SI Model for Pest Management

    Directory of Open Access Journals (Sweden)

    Lansun Chen

    2008-01-01

    Full Text Available An SI epidemic model with stage structure is investigated. In the model, impulsive biological control is taken, that is, we release infected pests to the field at a fixed time periodically. We get a sufficient condition for the global asymptotical stability of the pest-eradication periodic solution (0,0,I˜(t, and a condition for the permanence of the system. At last, a brief discussion shows that our results will be helpful for pest management.

  11. Real-time acoustic radiation force impulse imaging

    Science.gov (United States)

    Pinton, Gianmarco F.; McAleavey, Stephen A.; Dahl, Jeremy J.; Nightingale, Kathryn R.; Trahey, Gregg E.

    2005-04-01

    Acoustic Radiation Force Impulse (ARFI) imaging uses short duration acoustic pulses to generate and subsequently determine localized displacements in tissue. Time delay estimators, such as normalized cross correlation and phase shift estimation, form the computational basis for ARFI imaging. This paper considers these algorithms and the effects of noise, interpolation, and quadrature demodulation on the accuracy of the time delay estimates. These results are used to implement a real-time ARFI imaging system and in an ex vivo liver ablation study.

  12. Acoustic Radiation Force Impulse (ARFI) Imaging-Based Needle Visualization

    OpenAIRE

    Rotemberg, Veronica; Palmeri, Mark; Rosenzweig, Stephen; Grant, Stuart; MacLeod, David; Nightingale, Kathryn

    2011-01-01

    Ultrasound-guided needle placement is widely used in the clinical setting, particularly for central venous catheter placement, tissue biopsy and regional anesthesia. Difficulties with ultrasound guidance in these areas often result from steep needle insertion angles and spatial offsets between the imaging plane and the needle. Acoustic Radiation Force Impulse (ARFI) imaging leads to improved needle visualization because it uses a standard diagnostic scanner to perform radiation force based el...

  13. A Parallel Tracking Method for Acoustic Radiation Force Impulse Imaging

    OpenAIRE

    Dahl, Jeremy J.; Pinton, Gianmarco F.; Mark, L.; Agrawal, Vineet; Nightingale, Kathryn R.; TRAHEY, GREGG E.

    2007-01-01

    Radiation force-based techniques have been developed by several groups for imaging the mechanical properties of tissue. Acoustic Radiation Force Impulse (ARFI) imaging is one such method that uses commercially available scanners to generate localized radiation forces in tissue. The response of the tissue to the radiation force is determined using conventional B-mode imaging pulses to track micron-scale displacements in tissue. Current research in ARFI imaging is focused on producing real-time...

  14. Acoustic Radiation Force Impulse Imaging of Human Prostates ex vivo

    OpenAIRE

    Zhai, Liang; Madden, John; Foo, Wen-Chi; Palmeri, Mark L; Mouraviev, Vladimir; Polascik, Thomas J; Nightingale, Kathryn R.

    2010-01-01

    It has been challenging for clinicians using current imaging modalities to visualize internal structures and detect lesions inside human prostates. Lack of contrast among prostatic tissues and high false positive or negative detection rates of prostate lesions have limited the use of current imaging modalities in the diagnosis of prostate cancer. In this study, Acoustic Radiation Force Impulse (ARFI) imaging is introduced to visualize the anatomic and abnormal structures in freshly excised hu...

  15. An impulsive dynamical systems framework for reset control systems

    OpenAIRE

    Baños, Alfonso; Mulero, Juan I.; Barreiro, Antonio; Davó, Miguel A.

    2015-01-01

    Impulsive dynamical systems is a well-established area of dynamical systems theory, and it is used in this work to analyze several basic properties of reset control systems: existence and uniqueness of solutions, and continuous dependence on the initial condition (well-posedness). The work scope is about reset control systems with a linear and time-invariant base system, and a zero-crossing resetting law. A necessary and sufficient condition for existence and uniqueness of s...

  16. Boosted static multipole particles as sources of impulsive gravitational waves

    OpenAIRE

    Podolsky, J.; Griffiths, J. B.

    1998-01-01

    It is shown that the known solutions for nonexpanding impulsive gravitational waves generated by null particles of arbitrary multipole structure can be obtained by boosting the Weyl solutions describing static sources with arbitrary multipole moments, at least in a Minkowski background. We also discuss the possibility of boosting static sources in (anti-) de Sitter backgrounds, for which exact solutions are not known, to obtain the known solutions for null multipole particle...

  17. Behavior of impulsive fuzzy cellular neural networks with distributed delays

    Directory of Open Access Journals (Sweden)

    Kelin Li

    2007-04-01

    Full Text Available In this paper, we investigate a generalized model of fuzzy cellular neural networks with distributed delays and impulses. By employing the theory of topological degree, M-matrix and Lypunov functional, we find sufficient conditions for the existence, uniqueness and global exponential stability of both the equilibrium point and the periodic solution. Two examples are given to illustrate the results obtained here.

  18. Review of Impulse Noise Removal from Digital Video

    OpenAIRE

    RAVINDRA LUHACH; SHELEJ KHERA

    2013-01-01

    With the advancement in communication and information technology, legacy system are replaced by high speed computer as a result of this the world is shifting from analog to digital systems. Now, it is possible to transmit the digital videos over a communication channel and vice versa. Color video processing systems are used for a variety of purposes ranging from capturing scenes, processing of frames for feature extraction etc. Digital videos are generally contaminated by noise. Impulse noise...

  19. Naked Singularities, Cosmic Time Machines and Impulsive Events

    OpenAIRE

    FELICE, F

    2007-01-01

    Continued gravitational collapse gives rise to curvature singularities. If a curvature singularity is globally naked then the space-time may be causally future ill-behaved admitting closed time-like or null curves which extend to asymptotic distances and generate a Cosmic Time Machine (de Felice (1995) Lecture Notes in Physics 455, 99). The conjecture that Cosmic Time Machines give rise to high energy impulsive events is here considered in more details.

  20. Morphological Filtering Algorithm for Restoring Images Contaminated by Impulse Noise

    Directory of Open Access Journals (Sweden)

    Jorge Domingo Mendiola-Santibañez

    2015-01-01

    Full Text Available In this paper a methodology to restore gray scale images with pixels polluted by random impulsive noise is presented. Noise is discovered using a criterion based on the white top-hat by reconstruction. Pixels detected as corrupted are restored using an iterative morphological algorithm built with extensive and antiex- tensive morphological transformations. The proposal is compared with the rank ordered mean filter (ROM and other morphological transformations reported in the current literature.

  1. A systematic review of impulse control disorders in Parkinson's disease.

    OpenAIRE

    Callesen, MB; Scheel-Krüger, J; Kringelbach, ML; Møller, A.

    2013-01-01

    Throughout the past decade it has been recognized that dopaminergic medication administered to remedy motor symptoms in Parkinson's disease is associated with an enhanced risk for impulse control disorders and related compulsive behaviors such as hobbyism, punding, and the dopamine dysregulation syndrome. These complications are relatively frequent, affecting 6-15.5% of patients, and they most often appear, or worsen, after initiation of dopaminergic therapy or dosage increase. Recently, impu...

  2. On Heat and Paper : From Hot Pressing to Impulse Technology

    OpenAIRE

    Lucisano, Marco Francesco Carlo

    2002-01-01

    Impulse technology is a process in which water is removedfrom a wet paper web by the combined action of mechanicalpressure and intense heat. This results in increased dewateringrates, increased smoothness on the roll side of the sheet, andincreased density. Although the potential benefits of impulsepressing have been debated over the past thirty years, itsindustrial acceptance has been prevented by web delamination,which is defined as a reduction in the z-directional strengthof paper. This th...

  3. Exact impulsive gravitational waves in spacetimes of constant curvature

    OpenAIRE

    Podolsky, J.

    2002-01-01

    Exact solutions exist which describe impulsive gravitational waves propagating in Minkowski, de Sitter, or anti-de Sitter universes. These may be either nonexpanding or expanding. Both cases in each background are reviewed here from a unified point of view. All the main methods for their construction are described systematically: the Penrose "cut and paste" method, explicit construction of continuous coordinates, distributional limits of sandwich waves, embedding from higher...

  4. Impulsive Hybrid Discrete-Continuous Delay Differential Equations

    OpenAIRE

    Lenz, Simon Manfred

    2014-01-01

    This thesis deals with impulsive hybrid discrete-continuous delay differential equations (IHDDEs). This new class of differential equations is highly challenging for two reasons. First, because of a dependency of the right-hand-side function on past states, with time delays that depend on the current state. Second, because both the right-hand-side function and the state itself are discontinuous at implicitly defined time points. The theoretical results and numerical methods presented in ...

  5. Chimpanzees use self-distraction to cope with impulsivity

    OpenAIRE

    Evans, Theodore A.; Beran, Michael J.

    2007-01-01

    It is unknown whether animals, like humans, can employ behavioural strategies to cope with impulsivity. To examine this question, we tested whether chimpanzees (Pan troglodytes) would use self-distraction as a coping strategy in a situation in which they had to continually inhibit responses to accumulating candies in order to earn a greater amount of those rewards. We tested animals in three conditions in which they were sometimes given a set of toys and were sometimes allowed physical access...

  6. Volatility impulse response functions for multivariate GARCH models

    OpenAIRE

    Hafner, Christian; Herwatz, Helmut

    2001-01-01

    In the empirical analysis of financial time series, multivariate GARCH models have been used in various forms. As it is typical for nonlinear models there is yet no unique framework available to uncover dynamic covariance relationships for vector return processes. We introduce a new concept of impulse response functions tracing the effects of independent shocks on volatility through time. The advocated methodology avoids typical orthogonalization and ordering problems. Theoretical properties ...

  7. A Novel Chaotic Synchronization Scheme Based on Impulsive Stability Theory

    Directory of Open Access Journals (Sweden)

    Mengfan Cheng

    2012-03-01

    Full Text Available This paper introduces a new chaotic synchronization scheme based on impulsive stability theory. The synchronization of two identical chaotic systems with parametric uncertainties and mismatch is considered. Some sufficient conditions are developed to guarantee the robust synchronization of the chaotic systems. Compared with existing schemes, the amount of information transmitted between the two systems is reduced significantly. A numerical example is presented to demonstrate the effectiveness of the method.

  8. Estimation of channel impulse response and FPGA simulation

    Directory of Open Access Journals (Sweden)

    YU Longjie

    2015-02-01

    Full Text Available Wideband code division multiple access (WCDMA is a 3G wireless communication network.The common pilot channel in downlink of WCDMA provides an effective method to estimate the channel impulse response.In this paper,universal software radio peripheral (USRP is utilized to sample and process WCDMA signal which is emitted by China Unicom base station.Firstly,the received signal is pre-processed with filtering and down-sampling.Secondly,fast algorithm of WCDMA cell search is fulfilled.Thirdly,frequency shift caused by USRP?s crystal oscillator is checked and compensated.Eventually,channel impulse response is estimated.In this paper,MATLAB is used to describe the above algorithm and field programmable gate array (FPGA is used to simulate algorithm.In the process of simulation,pipeline and IP core multiplexing are introduced.In the case of 32 MHz clock frequency,FPGA simulation time is 80.861 ms.Simulation results show that FPGA is able to estimate the channel impulse response quickly and accurately with less hardware resources.

  9. Eroding ribbon thermocouples: impulse response and transient heat flux analysis

    Science.gov (United States)

    Buttsworth, David R.; Stevens, Robert; Stone, C. Richard

    2005-07-01

    We have investigated a particular type of fast-response surface thermocouple to determine if it is appropriate to use a one-dimensional transient heat conduction model to derive the transient surface heat flux from the measurements of surface temperature. With these sensors, low thermal inertia thermocouple junctions are formed near the surface by abrasive wear. Using laser excitation, we obtained the impulse response of these commercially available devices. The response of particular sensors can vary if new junctions are created by abrasive wear. Furthermore, the response of these sensors was found to deviate substantially from the one-dimensional model and varied from sensor to sensor. The impulse response was simulated with greater fidelity using a two-dimensional finite element model, but three-dimensional effects also appear to be significant. The impact of these variations on the derived heat flux is assessed for the case of measurements in an internal combustion engine. When the measured impulse response is used to derive the surface heat flux, the apparent reversal of heat flux during the expansion stroke does not occur.

  10. Low prolactin response to fenfluramine in impulsive aggression.

    Science.gov (United States)

    New, Antonia S; Trestman, Robert F; Mitropoulou, Vivian; Goodman, Marianne; Koenigsberg, Harold H; Silverman, Jeremy; Siever, Larry J

    2004-01-01

    To examine the prolactin (prl) response to d,l-fenfluramine in a large sample of personality disorder patients with impulsive aggression. Patients were screened from clinics at the Bronx VAMC and the Mount Sinai Medical Center and from press releases. One hundred and forty-six personality disorder patients (90M;56F) and 23 normal controls (15M;8F) underwent oral d,l-fenfluramine challenge. The peak change in prolactin(deltapkprl) was calculated by subtracting baseline prolactin from peak response following fenfluramine administration (3 h). Analysis of variance and regression analysis were used to detect group differences in deltapkprl. Deltapkprl in impulsive aggressive men, but not women, with personality disorders was blunted compared with controls. Men with suicide histories also had a blunted deltapkprl compared with those without, which was not accounted for by depression. This study represents a replication of previous studies, in a much larger sample, showing a blunted PRL response to fenfluramine of male patients with personality disorder in relation to impulsive aggression and to suicide attempts. PMID:15003426

  11. Design of shielded voltage divider for impulse voltage measurement

    International Nuclear Information System (INIS)

    The dividers used for the study of the insulation and electric discharge phenomena in high voltage equipments have the problems of the change of response characteristics owing to adjacent bodies and of induced noise. To improve the characteristics, the enclosed type divider shielded with metal has been investigated, and the divider of excellent response has been obtained by adopting the frequency-separating divider system, which is divided into two parts, resistance divider (lower frequency region) and capacitance divider (higher frequency region), for avoiding to degrade the response. Theoretical analysis was carried out in the cases that residual inductance can be neglected or can not be neglected in the small capacitance divider, and that the connecting wires are added. Next, the structure of the divider and the design of the electric field for the divider manufactured on the basis of the theory are described. The response characteristics were measured. The results show that 1 MV impulse voltage can be measured within the response time of 10 ns. Though this divider aims at the impulse voltage, the duration time of which is about that of standard lightning impulse, in view of the heat capacity because of the input resistance of 10.5 k?, it is expected that the divider can be applied to the voltage of longer duration time by increasing the input resistance in future. (Wakatsuki, Y.)

  12. Temperature of the Source Plasma for Impulsive Solar Energetic Particles

    CERN Document Server

    Reames, Donald V; Kahler, Stephen W

    2015-01-01

    The steep power-law dependence of element abundance enhancements on the mass-to-charge ratios [A/Q] of the ions in impulsive solar energetic-particle (SEP) events causes these enhancements to reflect the temperature-dependent pattern of Q of the ions in the source plasma. We searched for SEP events from coronal plasma that is hotter or cooler than the limited region of 2.5 - 3.2 MK previously found to dominate 111 impulsive SEP events. Fifteen new events were found, four (three) originated in 2-MK (4-MK) plasma, but none from outside this temperature range. Although the impulsive SEP events are strongly associated with flares, this result indicates that these ions are not accelerated from flare-heated plasma, which can often exceed 10 MK. Evidently the ions of 2 - 20 MeV/amu that we observe in space are accelerated from active-region plasma on open magnetic-field lines near the flare, but not from the closed loops of the flare. The power-law dependence of the abundance enhancements on A/Q of the ions is expec...

  13. Obsessive compulsive disorder and impulse control disorder comorbidity and evaluation of impulsivity and compulsivity in alcohol dependent patients

    Directory of Open Access Journals (Sweden)

    buket belkiz gungor

    2014-01-01

    Results: There was at least one ICD in 24.6 of the alcohol dependent patients. The most commonly encountered subtype was pathological gambling (16.0 which was followed by intermittent explosive disorder (6.1 and compulsive shopping (3.7. 13.5 of the patients were diagnosed with OCD while OCD at a subclinical level was found in 19.8 of them. 46.9 of the patients presented either with "obsessive compulsive traits" or ICD or both. Conclusion: In addition to the evaluation of impulsivity and compulsivity with using scales, OCD and ICD comorbidity was investigated in alcohol dependent patients. Together with the not otherwise specified impulse control disorders, at least one ICD was found in 24.6 of the addicts while 13.5 presented with OCD comorbidity.

  14. Impulsive moving mirror model and the stability of Schroedinger equation with impulse effect in a Banach space

    International Nuclear Information System (INIS)

    From a special class of systems has been used a Schroedinger equation with impulse effect in Minkowski space field theory with time dependent boundary conditions, i.e. those of moving mirrors. The field theoretical approach for studying the properties of the vacuum starts from an analysis of the behaviour of local field quantities in Minkowski space with uniformly moving mirrors. For the impulsive moving mirror model is the real process of interaction between the quantum field and the external mirror a subject to disturbances in its evolution acting in time very short compared with the entire duration of the process. So the stability of the solution of the Schroedinger evolution equation for the process in the stability of the vacuum of Casimir. 8 refs

  15. Trait Impulsive Choice Predicts Resistance to Extinction and Propensity to Relapse to Cocaine Seeking: A Bidirectional Investigation

    OpenAIRE

    Broos, N.; Diergaarde, L.; Schoffelmeer, A.N.M.; Pattij, T.; De Vries, T.J.

    2012-01-01

    Despite the strong association between impulsivity and addiction in humans, it is still a matter of debate whether impulsive choice predisposes to, or results from, drug dependence. Furthermore, it is unknown whether treating impulsivity can protect against relapse propensity. Therefore, this study explored the bidirectional relationship between impulsive choice and cocaine taking and seeking in rat behavioral models. In experiment 1, to determine whether impulsive choice predisposes to cocai...

  16. Novel Approach of Designing Multiplier-less Finite Impulse Response Filter using Differential Evolution Algorithm

    Directory of Open Access Journals (Sweden)

    Abhijit Chandra

    2012-04-01

    Full Text Available Reduction of computational complexity of digital hardware has drawn the special attention of researchers in recent past. Proper emphasis is needed in this regard towards the settlement of computationally efficient as well as functionally competent design of digital systems. In this communication, we have made one novel attempt for designing multiplier-free Finite duration Impulse Response (FIR digital filter using one robust evolutionary optimization technique, called Differential Evolution (DE. The search has been directed through two sequentially opposite paths which include quantization and optimization as fundamental operations. Besides performing a detailed comparative analysis between these two proposed approaches; the performance evaluation of the designed filter with other existing discrete coefficient FIR models has also been carried out. Finally, the optimum search method for realizing the required set of specifications has been suggested.

  17. THEORETICAL ANALYSIS OF DYNAMIC RESPONSE OF A BRIDGE SECTION LOADING BY THE IMPULSIVE FORCE

    Directory of Open Access Journals (Sweden)

    ADRIAN LEOPA

    2012-06-01

    Full Text Available The work in seismic design of bridges is needed to develop physical models and mathematical theory, based on which will be assessed and quantified the dynamic response of bridge structures subjected to stress arising from road traffic or seismic activity. The need for this modeling is imposed three requirements: to ensure the structural integrity of the bridge elements for subjected impulsive, proper choice of dynamic insulation elements placed as a interface between the superstructure and infrastructure, as well as analysis of effects on joints in these situations demand. This paper proposes a physical model of a general nature, enabling customization depending on the specific constructive bridge, or the way it is solicited. Customize this model was developed for this study based on the existing viaduct Transylvania highway located between km 29 +602.75 and km 29 +801.25.

  18. Parity violation in quasielastic electron-nucleus scattering within the relativistic impulse approximation

    CERN Document Server

    González-Jiménez, R; Donnelly, T W

    2015-01-01

    We study parity violation in quasielastic (QE) electron-nucleus scattering using the relativistic impulse approximation. Different fully relativistic approaches have been considered to estimate the effects associated with the final-state interactions. We have computed the parity-violating quasielastic (PVQE) asymmetry and have analyzed its sensitivity to the different ingredients that enter in the description of the reaction mechanism: final-state interactions, nucleon off-shellness effects, current gauge ambiguities. Particular attention has been paid to the description of the weak neutral current form factors. The PVQE asymmetry is proven to be an excellent observable when the goal is to get precise information on the axial-vector sector of the weak neutral current. Specifically, from measurements of the asymmetry at backward scattering angles good knowledge of the radiative corrections entering in the isovector axial-vector sector can be gained. Finally, scaling properties shown by the interference $\\gamma...

  19. Impulsivity is associated with the disinhibition but not restraint factor from the Three Factor Eating Questionnaire.

    Science.gov (United States)

    Yeomans, Martin R; Leitch, Margaret; Mobini, Sirous

    2008-01-01

    Recent data implicate impulsivity as a personality trait associated with obesity, binge eating and restrained eating. However, impulsivity is recognised as having multiple dimensions, and it remains unclear which aspects of impulsive behaviour best predict disordered eating. To try and elucidate further the relationship between impulsivity and eating behaviour, 147 women completed a behavioural measure and two self-report measures of impulsivity along with the Three Factor Eating Questionnaire (TFEQ). Overall scores on the Barratt Impulsiveness Scale (BIS-II), along with scores on the Non-planning and Motor Subscales of the BIS-II, were higher in women scoring high on the TFEQ disinhibition (TFEQ-D) scale. Likewise, women scoring high on the TFEQ-D showed more impulsive choice when discounting hypothetical monetary awards. However, responses to measures of functional relative to dysfunctional impulsivity did not differ depending on TFEQ-D score. No measure of impulsivity was related to scores on the TFEQ restraint scale. These data suggest that a tendency to act impulsively is associated with a tendency to overeat, and may be a factor which predicts the likelihood of the development of binge eating and the breakdown of dieting. PMID:18069081

  20. Impulsivity and overeating in children in the absence and presence of hunger.

    Science.gov (United States)

    Nederkoorn, Chantal; Dassen, Fania C M; Franken, Loes; Resch, Christine; Houben, Katrijn

    2015-10-01

    Overweight children appear to be more responsive to environmental, hedonic cues and easily overeat in the current obesogenic environment. They are also found to overeat in the absence of hunger, and this overeating seems related to impulsivity: impulsive participants are more prone to external eating. However, some studies showed that impulsive adults are also more prone to hunger cues: impulsive participants overate especially when feeling hungry. This would mean impulsive people are more reactive to both external and internal cues. The overeating was limited to palatable high energy-dense foods: hunger made them fancy a snack. In the current study, we wanted to test the interaction between impulsivity, hunger and consumption of food type in children. Impulsivity was measured in 88 children between the ages of 7 and 9. Next, half of the participants performed a taste test before their own regular lunch and half of the participants immediately after their lunch. During the taste test, low, medium and high energy-dense food items were presented. Results showed that impulsive children ate more high energy-dense foods than low impulsive children, both before and after their lunch. No differences were found on low or medium energy-dense foods. Impulsive children therefore showed normal sensitivity for internal hunger and satiety cues, but abnormal response to high energy-dense foods. This might render them vulnerable to tasty temptation in the environment and to weight gain in their future. PMID:25841646

  1. 3-D, Impulsive Magnetic Reconnection in a Laboratory Plasma (Invited)

    Science.gov (United States)

    Dorfman, S. E.; Ji, H.; Yamada, M.; Yoo, J.; Myers, C. E.; Roytershteyn, V.; Daughton, W. S.; Jara-Almonte, J.

    2013-12-01

    Magnetic reconnection is a fundamental plasma process involving the efficient conversion of magnetic field energy to plasma kinetic energy through changing field line topology. In many space and astrophysical systems, including the solar surface and the Earth's magnetotail, reconnection is not only fast, but also impulsive; in other words, a slow buildup phase is followed by a comparatively quick release of magnetic energy. An important question in the literature is if these examples of impulsive reconnection can be described by a two-dimensional model with no variation in the out-of-plane direction or if impulsive reconnection is fundamentally three-dimensional. Events observed on the Magnetic Reconnection Experiment (MRX) are characterized by large local gradients in the third direction and cannot be explained by 2-D models [1]. Detailed measurements show that the ejection of flux rope structures from the current sheet plays a key role in these events. By contrast, even though electromagnetic fluctuations in the lower hybrid frequency range are also observed concurrently with the impulsive behavior, they are not the key physics responsible. Furthermore, an important discrepancy in the layer width and force balance between the collisionless regime of MRX and kinetic simulations [2-4] persists when the fluctuations are small or absent, implying that they are not the cause of the wider electron layers observed in the experiment [5]. These wider layers may instead be due to the formation of flux ropes with a wide range of sizes; consistent with this hypothesis, flux rope signatures are observed down to the smallest scales resolved by the diagnostics. Finally, a qualitative, 3-D, two-fluid model is proposed to explain the observed disruptions. Many of the features observed in MRX including current disruptions [6], flux ropes [7], and electromagnetic fluctuations [8] have analogues in space observations. Thus, further detailed comparisons may enhance our understanding of space and astrophysical plasmas where impulsive reconnection occurs. In particular, this work has relevance to the upcoming Magnetospheric Multiscale (MMS) Mission which aims to understand how electron scale structure may affect the global reconnection process. [1] S. Dorfman, et. al., Geophys. Res. Lett. 40, 233-238 (2013). [2] S. Dorfman, et. al., Phys. Plasmas 15, 102107 (2008). [3] H. Ji, et. al., Geophys. Res. Lett., 35, L13106 (2008). [4] V. Roytershteyn, et. al., Phys. Plasmas 17, 055706 (2010). [5] V. Roytershteyn, et. al., Phys. Plasmas 20, 061212 (2013). [6] S. Ohtani, et. al., J. Geophys. Res., 97(A12), 19311-19324 (1992). [7] J. P. Eastwood, et. al., J. Geophys. Res., 112, A06235 (2007). [8] J. S. Pickett, et. al., J. Geophys. Res., 106(A9), 19081-19099 (2001).

  2. Global asymptotical synchronization of chaotic neural networks by output feedback impulsive control: An LMI approach

    International Nuclear Information System (INIS)

    In this paper, impulsive control for master-slave synchronization schemes consisting of identical chaotic neural networks is studied. Impulsive control laws are derived based on linear static output feedback. A sufficient condition for global asymptotic synchronization of master-slave chaotic neural networks via output feedback impulsive control is established, in which synchronization is proven in terms of the synchronization errors between the full state vectors. An LMI-based approach for designing linear static output feedback impulsive control laws to globally asymptotically synchronize chaotic neural networks is discussed. With the help of LMI solvers, linear output feedback impulsive controllers can be easily obtained along with the bounds of the impulsive intervals for global asymptotic synchronization. The method is finally illustrated by numerical simulations.

  3. Modelling and analysis of an impulsive SI model with Monod-Haldane functional response

    International Nuclear Information System (INIS)

    An impulsive SI model with Monod-Haldane functional response for pest control is proposed and investigated. First, we have proved that there exists an asymptotically stable pest-eradication periodic solution when the impulsive period is less than some critical value. Otherwise, the above system can be permanent. Then, influences of impulsive perturbation including impulse period, the time of spraying pesticide and the quantity of releasing infective pests on the above system have been studied. Moreover, numerical simulations show that the system has rich dynamical behaviors. Finally, it is concluded that the approach of combining impulsive infective releasing with impulsive pesticide spraying is more effective than the classical one if the chemical control is adopted rationally.

  4. The effect of citalopram hydrobromide on 5-HT2A receptors in the impulsive-aggressive dog, as measured with 123I-5-I-R91150 SPECT

    International Nuclear Information System (INIS)

    Involvement of the serotonergic system in impulsive aggression has been demonstrated in both human and animal studies. The purpose of the present study was to investigate the effect of citalopram hydrobromide (a selective serotonin re-uptake inhibitor) on the 5-HT2A receptor and brain perfusion in impulsive-aggressive dogs by means of single-photon emission computed tomography. The binding index of the radioligand 123I-5-I-R91150 was measured before and after treatment with citalopram hydrobromide in nine impulsive-aggressive dogs. Regional perfusion was measured with 99mTc-ethyl cysteinate dimer (ECD). Behaviour was assessed before treatment and again after 6 weeks of treatment. A correlation was found between decreased binding and behavioural improvement in eight out of nine dogs. The 5-HT2A receptor binding index was significantly reduced after citalopram hydrobromide treatment in all cortical regions but not in the subcortical area. None of the dogs displayed alterations in perfusion on the post-treatment scans. This study supports previous findings regarding the involvement of the serotonergic system in impulsive aggression in dogs in general. More specifically, the effect of treatment on the 5-HT2A receptor binding index could be demonstrated and the decreased binding index correlated with behavioural improvement. (orig.)

  5. Effect of dog breed and body conformation on vertical ground reaction forces, impulses, and stance times

    OpenAIRE

    Voss, K; Wiestner, T; Galeandro, L; Hässig, M; Montavon, P M

    2011-01-01

    OBJECTIVES: To assess whether fully normalised vertical ground reaction forces and stance times obtained at a trot depend on dog breed or body conformations. METHODS: Peak vertical forces (PVF), vertical impulses (VI), stance times (ST), and ratio of forelimb impulse to total impulse (RVI) of 54 dogs of seven different breeds were normalised to body weight and body size according to the theory of dynamic similarity, and were tested for differences between breeds. Breeds were Borzoi...

  6. APPLICATION OF STIMULUS & RESPONSE MODEL TO IMPULSE BUYING BEHAVIOR OF ALGERIAN CONSUMERS

    OpenAIRE

    Amel Graa; Maachou Dani-elKebir

    2012-01-01

    This paper investigates the influence of situational factors on the impulse buying behavior usinga Mehrabian and Russell's (1974) framework (Stimulus & response model). The results suggest thata consumer's emotions can be a mediating factor in the impulse purchase process. In this study, weidentify and explore how situational factors and emotional states may influence various dimensionsof impulse purchase behavior of Algerian shoppers. By tapping the responses of 687 consumers inthe area of A...

  7. The occurrence and experience of impulsivity and extreme positive mood in a non-clinical sample

    OpenAIRE

    Rawlings, Jodie

    2012-01-01

    The literature has struggled to reach an acceptable definition for the construct of impulsivity. Different models have variously suggested that the crux of the impulsivity construct lies in lack of planning, difficulties in concentration, failure of inhibition or attraction to sensation or immediate reward. More recently, research has suggested that impulsivity is increased in conditions of extreme affect, either positive or negative. The development of a novel measure of affective impulsivit...

  8. Impulsivity, Neural Deficits, and the Addictions: The “Oops” Factor in Relapse

    OpenAIRE

    Adinoff, Bryon; Rilling, Laurie M.; Williams, Mark J; Schreffler, Erica; Schepis, Ty S.; Rosvall, Traci; Rao,Uma

    2007-01-01

    Impulsive behaviors are observed in a wide range of psychiatric disorders, including substance use, bipolar, attention-deficit hyperactivity, antisocial and borderline personality, gambling, and eating disorders. The shared phenotype of impulsivity is thought to significantly contribute to both the etiology and perpetuation of these disorders. In this review, we focus upon the relevance of impulsivity to the addictive disorders, particularly substance use disorders. First, the literature supp...

  9. Impulsive choice and environmental enrichment: Effects of d-amphetamine and methylphenidate

    OpenAIRE

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

    2008-01-01

    Individual differences in impulsive choice and rearing in differential environments are factors that predict vulnerability to drug abuse. The present study determined if rearing influences impulsive choice, and if d-amphetamine or methylphenidate alters impulsive choice in differentially-reared rats. Male Sprague-Dawley rats were raised from 21 days of age in either an enriched condition (EC) or an isolated condition (IC) and were tested as young adults on an adjusting delay task. In this tas...

  10. The effects of impulsiveness and alcohol abuse on traffic code violations

    OpenAIRE

    Estrella Romero; José Antonio Gómez-Fraguela; Beatriz González-Iglesias; Jorge Sobral

    2012-01-01

    This paper examines the contribution of the facets assessed by the I7 Impulsiveness Questionnaire (viz., impulsiveness, venturesomeness and empathy), and of alcohol abuse, to the prediction of traffic rule violations controlling for the effect of variables such as age and annual mileage. To this end, a study was conducted on a sample of 535 drivers aged 20–73 years and the results were examined separately by gender. Based on them, impulsiveness and venturesomeness account for a substantial pr...

  11. Taking More, Now: The Optimality of Impulsive Choice Hinges on Environment Structure

    OpenAIRE

    Otto, A. Ross; Markman, Arthur B.; Love, Bradley C.

    2012-01-01

    Impulsivity is a stable personality trait associated with myopic choice behavior that favors immediate rewards over larger, delayed rewards and is often characterized as maladaptive inside and outside of the laboratory. An alternative view suggests that the consequences of trait impulsivity depend on the nature of the task environment. On this view, the optimal level of impulsivity varies across task payoff structures. This hypothesis is tested in two dynamic decision-making tasks that differ...

  12. Are self-injurers impulsive?:Results from two behavioral laboratory studies

    OpenAIRE

    Janis, Irene Belle; Nock, Matthew K

    2009-01-01

    Common clinical wisdom suggests that people who engage in self-injury are impulsive. However, virtually all prior work in this area has relied on individuals’ self-report of impulsiveness, despite evidence that people are limited in their ability to accurately report on cognitive processes that occur outside awareness. To address this knowledge gap, we used performance-based measures of several dimensions of impulsiveness to assess whether people engaging in non-suicidal self-injury (NSSI) de...

  13. Impulsivity and symptoms of nicotine dependence in a young adult population

    OpenAIRE

    Chase, Henry W.; Hogarth, Lee

    2011-01-01

    Introduction: Impulsivity is widely regarded as a risk factor for drug dependence. However, its relationship with the symptomatology of nicotine dependence is poorly understood. Methods: To examine the nature of these relationships, we recruited 404 daily and occasional smokers from a predominantly student population and assessed the association between impulsivity, as measured by the Barratt Impulsiveness Scale (BIS-11) and several self-reported measures of smoking rate and nicot...

  14. THE RELATIONSHIP BETWEEN IMPULSIVITY, -TAKING PROPENSITY AND NICOTINE DEPENDENCE AMONG OLDER ADOLESCENT SMOKERS

    OpenAIRE

    Ryan, Katherine K.; MacKillop, James; Carpenter, Matthew J.

    2012-01-01

    Impulsivity and risk-taking propensity are neurobehavioral traits that reliably distinguish between smoking and non-smoking adults. However, how these traits relate to smoking quantity and nicotine dependence among older adolescent smokers is unclear. The current study examined impulsivity and risk-taking propensity in relation to smoking behavior and nicotine dependence among current older adolescent smokers (age 16–20 years; N = 107). Participants completed the Barratt Impulsiveness Scale–1...

  15. Adaptive-impulsive synchronization in drive-response networks of continuous systems and its application

    Energy Technology Data Exchange (ETDEWEB)

    Sun Mei, E-mail: sunm@ujs.edu.c [Nonlinear Scientific Research Center, Jiangsu University, Zhenjiang, Jiangsu 212013 (China); Zeng Changyan; Tao Yangwei; Tian Lixin [Nonlinear Scientific Research Center, Jiangsu University, Zhenjiang, Jiangsu 212013 (China)

    2009-08-17

    Based on the comparison theorem for the stability of impulsive control system, adaptive-impulsive synchronization in drive-response networks of continuous systems with time-delay and non-time-delay is investigated. And the continuous control input, the simple updated laws and a linear impulsive controller are proposed. Moreover, two numerical examples are presented to verify the effectiveness and correctness of the theorem, using the energy resource system and Lue's system as the nodes of the networks.

  16. Mise en forme d'impulsions en phase et polarisation pour la microscopie non-linéaire.

    OpenAIRE

    Schön, Peter

    2010-01-01

    La mise en forme en amplitude, phase spectrale et polarisation des impulsions laser ultracourtes dans le régime femtoseconde peut fortement influencer le résultat d'une expérience d'optique non-linéaire. Dans cette thèse nous présentons un dispositif de façonnage d'impulsions basé sur l'utilisation de deux modulateurs spatiaux de lumière (SLM) pour contrôler ces trois propriétés simultanément et ce pour toutes les fréquences présentes dans l'impulsion. Une méthode basée sur la génération de s...

  17. Difference inequality for stability of impulsive difference equations with distributed delays

    Directory of Open Access Journals (Sweden)

    Long Shujun

    2011-01-01

    Full Text Available Abstract In this paper, we consider a class of impulsive difference equations with distributed delays. By establishing an impulsive delay difference inequality and using the properties of "?-cone" and eigenspace of the spectral radius of non-negative matrices, some new sufficient conditions for global exponential stability of the impulsive difference equations with distributed delays are obtained. An example is given to demonstrate the effectiveness of the theory.

  18. The Damage of ZnO Arrester Block Due To Multiple Impulse Currents

    OpenAIRE

    Tarcicius Haryono; K. Tunggul Sirait; Tumiran .; Hamzah Berahim

    2011-01-01

    A lightning arrester installed in an electrical power system is designed to protect some electrical equipment against damage due to lightning impulse strike. However, if there is a multiple impulse current striking a lightning arrester, it may damage the lightning arrester itself and then, as a result, it cannot provide lightning protection to the electrical equipment anymore. In this research, three peak values of lightning impulse current,which were 600, 1300, and 2500A, each of whic...

  19. Impulsive choice and workplace safety: A new area of inquiry for research in occupational settings

    OpenAIRE

    Reynolds, Brady; Schiffbauer, Ryan M.

    2004-01-01

    A conceptual argument is presented for the relevance of behavior-analytic research on impulsive choice to issues of occupational safety and health. Impulsive choice is defined in terms of discounting, which is the tendency for the value of a commodity to decrease as a function of various parameters (e.g., having to wait or expend energy to receive the commodity). A high degree of discounting is often considered an index of impulsivity. We argue that for workers, possible negative consequences...

  20. Impulse control disorders and related behaviours (ICD-RBs in Parkinson?s disease patients: Assessment using “Questionnaire for impulsive-compulsive disorders in Parkinson?s disease” (QUIP

    Directory of Open Access Journals (Sweden)

    Ashish Sharma

    2015-01-01

    Full Text Available Background: There is limited data on the prevalence of impulse control disorder and related behaviors (ICD-RBs in Indian patients with Parkinson?s Disease (PD. In the context of potential genetic and environmental factors affecting the expression of ICD-RBs, studying other multiethnic populations may bring in-sights into the mechanisms of these disorders. Objectives: To ascertain point prevalence estimate of ICD-RBs in Indian PD patients, using the validated “Questionnaire for Impulsive-Compulsive Disorders in Parkinson?s disease (QUIP” and to examine their association with Dopamine replacement therapy (DRT. Materials and Methods: This was a hospital based observational cross-sectional study. After taking informed consent, patients and their informants (spouse, or primary caregiver were made to complete the QUIP, and were instructed to answer questions based on behaviors that occurred anytime during PD that lasted at least four consecutive weeks. Results: Total of 299 patients participated in the study. At least one ICD-RB was present in 128 (42.8%, at least one Impulse control disorder (ICD was present in 74 (24.75% and at least one Impulse control related compulsive behaviour (ICRB was present in 93 (31.1% patients. Punding was the most frequent (12.4% followed by hyper sexuality (11.04%, compulsive hobbyism (9.4%, compulsive shopping (8.4%, compulsive medication use (7.7%, compulsive eating (5.35%, walkabout (4% and pathological gambling (3.3%. ? 2 ICD-RBs were observed in 15.7% of patients. After multivariate analysis, younger age of onset, being unmarried were specifically associated with presence of ICD. Longer disease duration was specifically associated with presence of ICRB. Whereas smoking and higher dopamine levodopa equivalent daily doses (DA LEDD were associated with both presence of ICD and ICRB. Higher LD LEDD was specifically associated with presence of ICD-RB. Conclusions: Our study revealed a relatively higher frequency of ICD-RBs, probably because of the use of screening instrument and because we combined both ICDs and ICRBs. Also high proportion of DA use (81.6% among our patients might be responsible. The role of genetic factors that might increase the risk of developing ICD-RBs in this population needs further exploration.

  1. Cued to Act on Impulse: More Impulsive Choice and Risky Decision Making by Women Susceptible to Overeating after Exposure to Food Stimuli.

    Science.gov (United States)

    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 responding (delayed discounting, DDT and a Go No-Go, GNG, task) and a measure of risky decision making (the balloon analogue risk task, BART) as well as questionnaire measures of impulsive behaviour either after looking at a series of pictures of food or visually matched controls. Impulsivity (DDT) and risk-taking (BART) were both positively associated with TFEQ-D scores, but in both cases this effect was exacerbated by prior exposure to food cues. No effects of restraint were found. TFEQ-D scores were also related to more commission errors on the GNG, while restrained women were slower on the GNG, but neither effect was modified by cue exposure. Overall these data suggest that exposure to food cues act to enhance general impulsive responding in women at risk of overeating and tentatively suggest an important interaction between tendency for impulsive decision making and food cues that may help explain a key underlying risk factor for overeating. PMID:26378459

  2. Exponential periodic attractor of impulsive BAM networks with finite distributed delays

    Energy Technology Data Exchange (ETDEWEB)

    Huang Zhenkun [Department of Mathematics, Zhejiang University, Hangzhou, Zhejiang 310027 (China); School of Sciences, Jimei University, Xiamen, Fujian 361021 (China)], E-mail: Huangdoc@tom.com; Xia Yonghui [Department of Mathematics, Fuzhou University, Fuzhou, Fujian 350002 (China)

    2009-01-15

    In this paper, we investigate a class of impulsive bidirectional associative memory (BAM) networks with both periodic coefficients and finite distributed delays. New criteria are established for the existence of an exponential periodic attractor, which generalize and improve the previously known results. Our criteria are less restrictive and can be applied to impulsive or non-impulsive BAM networks with a broad range of activation functions without differentiability and strict monotonicity. Moreover, our results are given in terms of system parameters and finite delay kernels of impulsive BAM networks by employing inequality technique, M-matrix and spectral theory. Finally, an example is given to show the feasibility and effectiveness of our results.

  3. Impulse Noise on Multi-Antenna Receiving System in WLAN Band

    Directory of Open Access Journals (Sweden)

    Asif Ahmed

    2014-07-01

    Full Text Available The effect of impulse noise in wireless communication has been a popular research topic for many researchers over the years. It has been observed that most of the wireless receivers are prone to the disturbing effects of impulsive and nonstationary noise that is generated from different manmade and natural sources. We had constructed a measurement system that acted as a multi-antenna wireless receiver for WLAN band. The measurement has been taken in an impulsive environment with impulse noise sources, such as drill machine, car ignition, etc. The received noise has been approximated by available noise models. The approximation with Gaussian-Gaussian model is presented in this paper.  

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

    Science.gov (United States)

    Buck, Karl

    2009-01-01

    The paper describes the problems that may occur when hearing protectors, usually designed for industrial noise environments, are used for high-level impulse (weapon) noise. The military impulse noise environment is described, as are the different types of passive and active hearing protectors and the measurement procedures. The different mechanisms that may alter the effectiveness of the hearing protectors as well as their global efficiency when submitted to high-level impulse noise are presented. The paper also discusses how the performance values accessible to the user may be used in different damage risk criteria for continuous and impulse noise. PMID:19534855

  5. Dynamic response of missile structures to impulsive loads caused by nuclear effects blowoff. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Cost, T.L.

    1976-06-01

    Two dynamic structural analysis computer codes have been developed for the analysis of missile type structures subjected to impulsive loads produced by nuclear effects blowoff. One code, IMPLATE, is applicable to flat plate structures prestressed by inplane mechanical and thermal loads and the other code, IMPSHELL, can be applied to thin cylindrical shell type structures preloaded by internal pressure. The impulsive loads are calculated with the aid of a photoelectric energy deposition code, KNISH, and a blowoff model. A theory for correlating the nuclear effects blowoff impulse with impulse produced by a laboratory simulation 'exploding fail' technique is presented.

  6. Impulsivity and pathological gambling: Is it a state or a trait problem?

    Directory of Open Access Journals (Sweden)

    Lai Florence DM

    2011-11-01

    Full Text Available Abstract Background This study tested 37 Chinese male pathological gamblers and 40 controls to understand the relationship between pathological gambling and impulsivity as a long-term trait or a short-term state in the cognitive and affective domain. Results Trait impulsivity was measured by the Barratt Impulsiveness Scale-11. State impulsivity in the cognitive and affective domains were measured by the Stroop Color Word Test and the Emotional Conflict Task, respectively. The pathological gamblers scored significantly higher than the controls on the Barratt Impulsiveness Scale-11. However, there were no significant group differences in performance on the Stroop Color Word Test or the Emotional Conflict Task. Conclusions Findings clearly show that pathological gambling is associated with trait but not state impulsivity. In other words, pathological gambling is associated with an impulsivity stemming from enduring personality characteristics that lead gamblers to focus on short-term gains (trait impulsivity rather than momentary cognitive or affective disinhibition (state impulsivity. Interventions should aim to change pathological gamblers' habitual functioning style by cultivating healthy reflection habits and focusing on long-term rewards.

  7. Indicator circuit for detection of after impulses in Geiger-Mueller counters

    International Nuclear Information System (INIS)

    In applications for monitoring it is supposed that the impulses are of constant form and height and the counting rate is low. The circuit should indicate after impulse an low counting rate but stop indicating at higher counting rates in order not to misinterpret a true second impulse coming shortly after the first as an after impulse. Temperature stability between -200C and +500C was also required. Two different circuits have been developed. The advantages and disadvantages of the two circuits are discussed. (G.Q.)

  8. Impulsive controller design for exponential synchronization of chaotic neural networks with mixed delays

    Science.gov (United States)

    Li, Xiaodi; Rakkiyappan, R.

    2013-06-01

    This paper considers the chaotic synchronization problem of neural networks with time-varying and distributed delays using impulsive control method. By utilizing the stability theory for impulsive functional differential equations, several impulsive control laws are derived to guarantee the exponential synchronization of neural networks with time-varying and distributed delays. It is shown that chaotic synchronization of the networks is heavily dependent on the designed impulsive controllers. Moreover, these conditions are expressed in terms of LMI and can be easily checked by MATLAB LMI toolbox. Finally, a numerical example and its simulation are given to show the effectiveness and advantage of the proposed control schemes.

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

    Science.gov (United States)

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

    2013-01-01

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

  10. DETECTION OF LANDMINES USING IMPULSE GROUND PENETRATING RADAR

    Directory of Open Access Journals (Sweden)

    RAMAKRISHNA PORANDLA

    2013-06-01

    Full Text Available Landmines are affecting the lives and livelihood of millions of people around the world. In this paper, we presentThe video impulse ground penetrating radar system for detection for small and shallow buried objects has been developed. The hardware combines commercially available components with components specially developed or modified for being used in the system. The GPR system has been desired to measure accurately electromagnetic field backscattered from subsurface targets in order to allow identification of detected targets through the solution of the inverse scattering problem. The GPR has been tested in different environmental conditions and has proved its ability to detect small and shallow buried targets.

  11. Discharge current modes of high power impulse magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Zhongzhen Wu

    2015-09-01

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

  12. Probing impulsive strain propagation with x-ray pulses

    CERN Document Server

    Reis, D A; Bucksbaum, P H; Clarke, R; Dufresne, E R; Hertlein, M P; Merlin, R; Falcone, R; Kapteyn, H C; Murnane, M; Larsson, J; Missalla, T; Wark, J; Missalla, Th.

    2001-01-01

    Pump-probe time-resolved x-ray diffraction of allowed and nearly forbidden reflections in InSb is used to follow the propagation of a coherent acoustic pulse generated by ultrafast laser-excitation. The surface and bulk components of the strain could be simultaneously measured due to the large x-ray penetration depth. Comparison of the experimental data with dynamical diffraction simulations suggests that the conventional model for impulsively generated strain underestimates the partitioning of energy into coherent modes.

  13. Advanced Impulse Detection & Reduction Based on Multimodal Filter

    Directory of Open Access Journals (Sweden)

    P. Thirumurugan

    2014-07-01

    Full Text Available Impulse noises are occurred in the images during image signal acquisition and processing from one location to another location. In this paper, the optimal detector noise filtering algorithm and its efficient hardware architecture is presented. The proposed architecture comprises of orthogonal direction pattern generation, sorter, thresholder, local binary converter, multimodal filter and pixel converter units respectively. The local binary converter unit detects and corrects the noise pixel efficiently using a simple logic circuit. The design possesses only two line memory buffers with very low computational complexity, thereby reducing the hardware cost and appropriate for several real-time applications.

  14. Observation of negative impulse velocity in free space

    OpenAIRE

    Budko, Neil V.

    2008-01-01

    Since the 1983 definition of the speed of light in vacuum as a fundamental constant with the exact value of 299792458 m/s the question remains as to what apart from the wavefront travels at that speed. It is commonly assumed that the entire wave-packet or an impulse of the electromagnetic radiation in free space does. Here it is shown, both theoretically and experimentally, that there exists a region close to the source, where, while the wave-front travels at the speed of li...

  15. Excitement tem-horn antenna by impulsive relativistic electron beam

    CERN Document Server

    Balakirev, V A; Egorov, A M; Lonin, Y F

    2000-01-01

    In the given operation the opportunity of reception powerful electromagnetic irradiation (EMI) is observationally explored by excitation by a impulsive relativistic electronic beam (IREB) of a TEM-horn antenna. It is revealed, that at such expedient of excitation of the TEM-horn antenna, the signal of radiation of the antenna contains three various components caused by oscillation of radiation by forward front IREB, high-voltage discharge between plates irradiation of TEM-horn antenna a and resonant properties of the antenna devices.

  16. Electro-impulse de-icing testing analysis and design

    Science.gov (United States)

    Zumwalt, G. W.; Schrag, R. L.; Bernhart, W. D.; Friedberg, R. A.

    1988-01-01

    Electro-Impulse De-Icing (EIDI) is a method of ice removal by sharp blows delivered by a transient electromagnetic field. Detailed results are given for studies of the electrodynamic phenomena. Structural dynamic tests and computations are described. Also reported are ten sets of tests at NASA's Icing Research Tunnel and flight tests by NASA and Cessna Aircraft Company. Fabrication of system components are described and illustrated. Fatigue and electromagnetic interference tests are reported. Here, the necessary information for the design of an EIDI system for aircraft is provided.

  17. Effects of Impulsive Pile-Driving Exposure on Fishes.

    Science.gov (United States)

    Casper, Brandon M; Carlson, Thomas J; Halvorsen, Michele B; Popper, Arthur N

    2016-01-01

    Six species of fishes were tested under aquatic far-field, plane-wave acoustic conditions to answer several key questions regarding the effects of exposure to impulsive pile driving. The issues addressed included which sound levels lead to the onset of barotrauma injuries, how these levels differ between fishes with different types of swim bladders, the recovery from barotrauma injuries, and the potential effects exposure might have on the auditory system. The results demonstrate that the current interim criteria for pile-driving sound exposures are 20 dB or more below the actual sound levels that result in the onset of physiological effects on fishes. PMID:26610952

  18. Application des impulsions attosecondes à la spectroscopie harmonique des molécules

    OpenAIRE

    Lin, Nan

    2013-01-01

    La génération d'harmoniques d'ordre élevé (HHG) est un processus non linéaire extrême qui peut être compris intuitivement par la séquence de trois étapes: i) ionisation tunnel de la cible atome/ molécule et création d'un paquet d'ondes électronique (EWP) dans le continuum, ii) accélération de l'EWP par le champ laser intense et iii) recombinaison avec le cœur ionique et émission d'une impulsion attoseconde de lumière cohérente dans l'extrême UV (XUV). La HHG fournit ainsi une source ultracour...

  19. Investigations on the balloon as an impulse source.

    Science.gov (United States)

    Pätynen, Jukka; Katz, Brian F G; Lokki, Tapio

    2011-01-01

    Measurements of impulses produced by bursting balloons are presented. Various sizes of balloons were popped with a mechanical device in an anechoic chamber and recorded with a spherical microphone array. The power responses and directivity of the balloons are analyzed. Results indicate that power responses have two emphasized frequencies which depend on balloon size and inflation level. Larger balloons radiated more energy and higher inflation levels resulted in stronger high frequency content. Balloon directivity patterns are stable over repetitions. However, balloons do not radiate omnidirectionally. The degree of omnidirectionality improves with balloon size and for midrange frequencies. PMID:21302978

  20. Albedo's determination by the method of neutron impulse

    International Nuclear Information System (INIS)

    Experiments with non-stationary neutron transport in large cavity moderators (l>>?sub(tr)-1) (where l is the characteristic cavity length and ?sub(tr)-1 the macroscopic transport section of the moderator) led to the method reported in this study which, based on neutron impulses for determining albedo of thermal neutrons, gave a precision greater by an order of magnitude over previous methods. A sufficient time interval after introduction of the neutron flux into the moderator chamber decreased exponentially the decay constant L, which was itself related to albedo by a function called f. Numerical calculations of albedo were assisted. (author)

  1. Infinite impulse response modal filtering in visible adaptive optics

    CERN Document Server

    Agapito, G; Quirós-Pacheco, F; Puglisi, A; Esposito, S

    2012-01-01

    Diffraction limited resolution adaptive optics (AO) correction in visible wavelengths requires a high performance control. In this paper we investigate infinite impulse response filters that optimize the wavefront correction: we tested these algorithms through full numerical simulations of a single-conjugate AO system comprising an adaptive secondary mirror with 1127 actuators and a pyramid wavefront sensor (WFS). The actual practicability of the algorithms depends on both robustness and knowledge of the real system: errors in the system model may even worsen the performance. In particular we checked the robustness of the algorithms in different conditions, proving that the proposed method can reject both disturbance and calibration errors.

  2. Delineating the psychic structure of substance abuse and addictions: should anxiety, mood and impulse-control dysregulation be included?

    Science.gov (United States)

    Pani, Pier Paolo; Maremmani, Icro; Trogu, Emanuela; Gessa, Gian Luigi; Ruiz, Pedro; Akiskal, Hagop Souren

    2010-05-01

    Current "official" nosology (e.g. DSM IV) is largely limited to physical manifestations of addiction that can be objectively observed and are suited to the maintaining of an "atheoretical" perspective. However, addicted subjects display additional psychiatric symptoms that affect their well-being and social functioning and, in accordance with DSM IV, are typically relegated to the domain of psychiatric "comorbidity." We contend that the relationship of these psychiatric symptoms with addiction is very close, as demonstrated by the high frequency of association observed. We further assert that substance use may modify pre-existing psychic structures such as temperament and related subthreshold conditions and lead to addiction as a specific mental disorder, inclusive also of symptoms pertaining to mood/anxiety, or impulse-control dimensions. The present contribution addresses the weaknesses of the current DSM-based nosology of addiction-related mental comorbidity. We highlight the overlap of the biological substrates and the neurophysiology of addictive processes and psychiatric symptoms associated with addiction, and propose the inclusion of specific mood, anxiety, and impulse-control dimensions in the psychopathology of addictive processes. We postulate that addiction reaches beyond the mere result of drug-elicited effects on the brain and cannot be peremptorily equated only with the use of drugs despite the adverse consequences produced. We infer that mood, anxiety and impulse-control dysregulation is at the very core of both the origins and clinical manifestations of addiction and should be incorporated into the nosology of the same, emphasising how addiction is a relapsing chronic condition in which psychiatric manifestations play a crucial role. To conclude, addictionology cannot be severed from its psychopathological connotations, in view of the undeniable presence of symptoms, of their manifest contribution to the way addicted patients feel and behave, and to the role they play in maintaining the continued use of substances. PMID:19584019

  3. Acoustic Radiation Force Impulse Elastography in the Diagnosis of Thyroid Nodules: Useful or Not Useful?

    Science.gov (United States)

    Zhang, Yi-Feng; Xu, Hui-Xiong; Xu, Jun-Mei; Liu, Chang; Guo, Le-Hang; Liu, Lin-Na; Zhang, Jing; Xu, Xiao-Hong; Qu, Shen; Xing, Mingzhao

    2015-10-01

    The goal of this study is to evaluate the diagnostic performance of acoustic radiation force impulse (ARFI) elastography for differentiating benign from malignant thyroid nodules. One hundred and seventy-four pathologically proven thyroid nodules (139 benign, 35 malignant) in 154 patients (mean age: 49.2 ± 12.1 y; range: 16-72 y) were included in this study. Conventional ultrasound (US) and ARFI elastography using virtual touch tissue imaging (VTI) and virtual touch tissue quantification (VTQ) were performed to examine the thyroid nodules. Two blinded readers with different amounts of experience independently scored the likelihood of malignancy on the basis of a five-point scale in three different image-reading sets. The diagnostic performances among different image-reading sets and between the two readers were compared. The diagnostic specificity of both readers improved significantly after reading the VTI images or both VTI and VTQ images (all p ARFI elastography improves the specificity in diagnosing malignant thyroid nodules compared with conventional US on its own. ARFI elastography particularly facilitates the specific diagnosis for thyroid nodules smaller than 1.0 cm. ARFI elastography is also able to increase the diagnostic confidence of the readers. PMID:26119458

  4. Role of serotonin transporter function in rat orbitofrontal cortex in impulsive choice.

    Science.gov (United States)

    Darna, Mahesh; Chow, Jonathan J; Yates, Justin R; Charnigo, Richard J; Beckmann, Joshua S; Bardo, Michael T; Dwoskin, Linda P

    2015-10-15

    Impulsivity is a multi-faceted personality construct that plays a prominent role in drug abuse vulnerability. Dysregulation of 5-hydroxytryptamine (serotonin, 5-HT) systems in subregions of the prefrontal cortex has been implicated in impulsivity. Extracellular 5-HT concentrations are regulated by 5-HT transporters (SERTs), indicating that these transporters may be important molecular targets underlying individual differences in impulsivity and drug abuse vulnerability. The present study evaluated the role of SERT in mediating individual differences in impulsivity. Rats were tested for both impulsive action using the cued go/no-go task and for impulsive choice using a delay discounting task in a counterbalanced design. Following behavioral evaluation, Km and Vmax were obtained from kinetic analysis of [(3)H]5-HT uptake by SERT using synaptosomes prepared from both orbitofrontal cortex (OFC) and medial prefrontal cortex (mPFC) obtained from each individual rat. Vmax for SERT in OFC, but not mPFC, was negatively correlated with mean adjusted delay scores in the delay discounting task. In contrast, Vmax for SERT in OFC and mPFC was not correlated with performance in the cued go/no-go task. To further evaluate the relationship between SERT function and impulsive choice, a selective SERT inhibitor, fluoxetine (0, 15, 50 and 150pmol/side) was microinjected bilaterally into OFC and effects on the delay discounting task determined. Following stabilization of behavior, fluoxetine increased mean adjusted delay scores (decreased impulsivity) in high impulsive rats compared to saline microinjection, but had no effect in low impulsive rats. These ex vivo and in vivo results suggest that enhanced SERT function in OFC underlies high impulsive choice behavior. PMID:26183652

  5. Transition Region Abundance Measurements During Impulsive Heating Events

    CERN Document Server

    Warren, Harry P; Doschek, George A; Feldman, Uri

    2015-01-01

    It is well established that elemental abundances vary in the solar atmosphere and that this variation is organized by first ionization potential (FIP). Previous studies have shown that in the solar corona low-FIP elements, such as Fe, Si, Mg, and Ca, are generally enriched relative to high-FIP elements, such as C, N, O, Ar, and Ne. In this paper we report on measurements of plasma composition made during impulsive heating events observed at transition region temperatures with the Extreme Ultraviolet Imaging Spectrometer (EIS) on Hinode. During these events the intensities of O IV, V, and VI emission lines are enhanced relative to emission lines from Mg V, VI, and VII and Si VI and VII and indicate a composition close to that of the photosphere. Long-lived coronal fan structures, in contrast, show an enrichment of low-FIP elements. We conjecture that the plasma composition is an important signature of the coronal heating process, with impulsive heating leading to the evaporation of unfractionated material from...

  6. A distorted wave impulse approach for atom--diatom collisions

    International Nuclear Information System (INIS)

    A formalism is derived to include the effects of the long-range attractive part of the interaction potential in the calculation of atom--diatom collision cross sections using the impulse approach (IA). These calculations have, until now, assumed the atom--diatom potential given by a sum of two atom--atom interactions, consequently yielding a poor representation of the long-range attractive part. In the distorted wave impulse approach (DWIA) the long-range attractive part, located at the center of mass of the diatom, is a spherically symmetric potential which ''distorts'' the incoming and outgoing waves. The DWIA formalism is used to calculate differential cross sections for the rotationally inelastic process Li++N2(v=0, j=2)?Li++N2(v'=0, j'), as a function of the final rotational level j', at a relative kinetic energy of 4.23 eV and center of mass scattering angles of 49.2 degree and 37.1 degree. It is shown that differential cross sections calculated using the DWIA formalism are in much better agreement with experimentally measured ones than IA differential cross sections using atom--atom interactions expressed by either hard-core, or exponential repulsive, functions

  7. THE EMISSION MEASURE DISTRIBUTION OF IMPULSIVE PHASE FLARE FOOTPOINTS

    Energy Technology Data Exchange (ETDEWEB)

    Graham, D. R.; Hannah, I. G.; Fletcher, L. [School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Milligan, R. O., E-mail: d.graham.3@research.gla.ac.uk [Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom)

    2013-04-10

    The temperature distribution of the emitting plasma is a crucial constraint when studying the heating of solar flare footpoints. However, determining this for impulsive phase footpoints has been difficult in the past due to insufficient spatial resolution to resolve the footpoints from the loop structures, and a lack of spectral and temporal coverage. We use the capabilities of Hinode/Extreme Ultraviolet Imaging Spectrometer to obtain the first emission measure distributions (EMDs) from impulsive phase footpoints in six flares. Observations with good spectral coverage were analyzed using a regularized inversion method to recover the EMDs. We find that the EMDs all share a peak temperature of around 8 MK, with lines formed around this temperature having emission measures (EMs) peaking between 10{sup 28} and 10{sup 29} cm{sup -5}, indicating a substantial presence of plasma at very high temperatures within the footpoints. An EMD gradient of EM(T) {approx} T is found in all events. Previous theoretical work on EM gradients shows this to be consistent with a scenario in which the deposited flare energy directly heats only the top layer of the flare chromosphere, while deeper layers are heated by conduction.

  8. Impulsive Loading of Armour by High Explosive Squash Head Munition

    Directory of Open Access Journals (Sweden)

    P.U. Deshpande

    2003-10-01

    Full Text Available Results obtained by theoretical modelling studies involving classical stress-strain theories, duly validated by experimental investigation in understanding the mechanism of impulsive loading (scabbing and blast under dynamic and static conditions, are discussed. This concept has been used in designing a high explosive squash head ammunition being effective in defeating monolithic armour. Efforts have been made to carry out an in-depth study in understanding the mechanism of scabbing under static and dynamic (live firing conditions. For this purpose, a one-dimensional computer code has been used to predict the spread of explosive against time on the target. The simulations were carried out using a 2-D Lagrangian hydrodynamic code for scabbing effect. The blast effect that follows under static and dynamic conditions has also been studied. Blast parameters have been computed in terms of TNT equivalent and compared with experimental results. The events occurring during impulsive loading of 135 mm monolithic rolled homogenous armour have been illustrated.

  9. Sudden impulse observations in the dayside magnetosphere by THEMIS

    Science.gov (United States)

    Samsonov, A. A.; Sibeck, D. G.; Walsh, B. M.; Zolotova, N. V.

    2014-12-01

    We present a study of the magnetospheric response to interplanetary shocks. We show eight events with simultaneous observations of sudden impulses in the dayside magnetosphere and interplanetary shocks in the solar wind. The spacecraft measurements in the equatorial plane, even those very close to the Earth, can be interpreted in terms of the vortices predicted by previous studies employing global MHD models. In fact, these vortices are velocity oscillations with the properties of Alfvén waves. The amplitude and frequency of the oscillations depend on radial distance from the Earth. The amplitude of the velocity perturbations decreases with increase of the density and magnetic field magnitude, but the velocity amplitude shows no dependence on magnitude of the solar wind dynamic pressure change attending the interplanetary shocks. The oscillations are observed both in the outer magnetosphere and the plasmasphere, but they become less sinusoidal near the plasmapause, i.e., in the region with a large-density gradient. The amplitude of the magnetic field enhancement in the sudden impulses also depends on the radial distance. The MHD simulations successfully predict the amplitudes of magnetic field increase and the first cycles of the velocity oscillations in these events.

  10. Impulsive Heating of Solar Flare Ribbons Above 10 MK

    Science.gov (United States)

    Simões, P. J. A.; Graham, D. R.; Fletcher, L.

    2015-06-01

    The chromospheric response to the input of flare energy is marked by extended extreme ultraviolet (EUV) ribbons and hard X-ray (HXR) footpoints. These are usually explained as the result of heating and bremsstrahlung emission from accelerated electrons colliding in the dense chromospheric plasma. We present evidence of impulsive heating of flare ribbons above 10 MK in a two-ribbon flare. We analyse the impulsive phase of SOL2013-11-09T06:38, a C2.6 class event using data from Atmospheric Imaging Assembly (AIA) on board of the Solar Dynamics Observatory (SDO) and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) to derive the temperature, emission measure and differential emission measure of the flaring regions and investigate the evolution of the plasma in the flaring ribbons. The ribbons were visible at all SDO/AIA EUV/UV wavelengths, in particular, at 94 and 131 Å filters, sensitive to temperatures of 8 MK and 12 MK. The time evolution of the emission measure of the plasma above 10 MK at the ribbons has a peak near the HXR peak time. The presence of hot plasma in the lower atmosphere is further confirmed by a RHESSI imaging spectroscopy analysis, which shows resolved sources at 11 - 13 MK that are associated with at least one ribbon. We found that collisional beam-heating can only marginally explain the power necessary to heat the 10 MK plasma at the ribbons.

  11. Impulsive Heating of Solar Flare Ribbons Above 10 MK

    CERN Document Server

    Simões, Paulo J A; Fletcher, Lyndsay

    2015-01-01

    The chromospheric response to the input of flare energy is marked by extended extreme ultraviolet (EUV) ribbons and hard X-ray (HXR) footpoints. These are usually explained as the result of heating and bremsstrahlung emission from accelerated electrons colliding in the dense chromospheric plasma. We present evidence of impulsive heating of flare ribbons above 10 MK in a two-ribbon flare. We analyse the impulsive phase of SOL2013-11-09T06:38, a C2.6 class event using data from Atmospheric Imaging Assembly (AIA) on board of Solar Dynamics Observatory (SDO) and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) to derive the temperature, emission measure and differential emission measure of the flaring regions and investigate the evolution of the plasma in the flaring ribbons. The ribbons were visible at all SDO/AIA EUV/UV wavelengths, in particular, at 94 and 131 \\AA\\ filters, sensitive to temperatures of 8 MK and 12 MK. Time evolution of the emission measure of the plasma above 10 MK at the ribb...

  12. Solar Flare Impulsive Phase Observations from SDO and Other Observatories

    Science.gov (United States)

    Chamberlin, Phillip C.; Woods, Thomas N.; Schrijver, Karel; Warren, Harry; Milligan, Ryan; Christe, Steven; Brosius, Jeffrey W.

    2010-01-01

    With the start of normal operations of the Solar Dynamics Observatory in May 2010, the Extreme ultraviolet Variability Experiment (EVE) and the Atmospheric Imaging Assembly (AIA) have been returning the most accurate solar XUV and EUV measurements every 10 and 12 seconds, respectively, at almost 100% duty cycle. The focus of the presentation will be the solar flare impulsive phase observations provided by EVE and AIA and what these observations can tell us about the evolution of the initial phase of solar flares. Also emphasized throughout is how simultaneous observations with other instruments, such as RHESSI, SOHO-CDS, and HINODE-EIS, will help provide a more complete characterization of the solar flares and the evolution and energetics during the impulsive phase. These co-temporal observations from the other solar instruments can provide information such as extending the high temperature range spectra and images beyond that provided by the EUV and XUV wavelengths, provide electron density input into the lower atmosphere at the footpoints, and provide plasma flows of chromospheric evaporation, among other characteristics.

  13. The iterative shrinkage method for impulsive noise reduction from images

    International Nuclear Information System (INIS)

    In this paper, we present a novel scheme to compensate impulsive noise from images using the sparse shrinkage method. In this scheme, we assume the remaining noise after using a simple median filtering in place of corrupted pixels, found by boundary discriminative noise detection method, to be Gaussian additive noise. This assumption will later be verified by the means of simulation. Knowing that the pure image in the discrete wavelet transform (DWT) domain is a sparse vector, we define an optimization problem to minimize the l0-norm of the estimated image vector from the noisy one in the DWT domain. l0-norm makes the optimization problem a combinatorial optimization problem which is NP-hard to solve. To come up with a solution for our optimization problem, we convert the l0-norm problem to a continuous optimization problem which is then solved to find the estimated image with reduced noise. In the simulation and discussion part, the performance of our proposed method in reducing impulsive noise is compared to that of existing methods in the literature. We show that our proposed algorithm generally performs better in terms of both subjective and objective evaluations and is less complex. (paper)

  14. Effect of casing yield stress on bomb blast impulse

    Directory of Open Access Journals (Sweden)

    Hutchinson M.D.

    2012-08-01

    Full Text Available An equation to predict blast effects from cased charges was first proposed by U. Fano in 1944 and revised by E.M. Fisher in 1953 [1]. Fisher’s revision provides much better matches to available blast impulse data, but still requires empirical parameter adjustments. A new derivation [2], based on the work of R.W. Gurney [3] and G.I. Taylor [4], has resulted in an equation which nearly matches experimental data. This new analytical model is also capable of being extended, through the incorporation of additional physics, such as the effects of early case fracture, finite casing thickness, casing metal strain energy dissipation, explosive gas escape through casing fractures and the comparative dynamics of blast wave and metal fragment impacts. This paper will focus on the choice of relevant case fracture strain criterion, as it will be shown that this allows the explicit inclusion of the dynamic properties of the explosive and casing metal. It will include a review and critique of the most significant earlier work on this topic, contained in a paper by Hoggatt and Recht [5]. Using this extended analytical model, good matches can readily be made to available free-field blast impulse data, without any empirical adjustments being needed. Further work will be required to apply this model to aluminised and other highly oxygen-deficient explosives.

  15. Autonomous gauge for blast impulse determination close to explosive charges

    Science.gov (United States)

    Kisters, T.; Kuder, J.; Nau, S.

    2015-08-01

    This paper reports on a new gauge for blast impulse determination close to explosive charges. The gauge is based on the autonomous data recorder g-rec developed at the Ernst-Mach-Institute for data acquisition in harsh environments. Combined with an acceleration sensor these data recorders allow for the direct determination of the momentum transferred to an object by a blast wave even in the immediate vicinity of the explosive charge. From this the blast impulse can be determined. Using autonomous electronics distinct advantages are gained compared to classical passive momentum traps. The paper summarizes the properties of the g-rec recorder and describes the setup of the autonomous momentum trap in detail. Numerical simulations are presented which illustrate the gauge performance and its limitations. Tests with 1 kg charges demonstrate the feasibility of the approach. Good agreement was found between simulations and tests. The application range of the gauges is determined by the measurement range of the built-in acceleration sensor and its overall dimensions and weight. The present configuration is designed for distances between ˜ 0.3 and 1 m from charges between several 100 g and several kilograms. Data were successfully collected down to reduced distances of 0.25 m/kg^{1/3} . Minor changes in gauge dimensions, weight, or measurement range enable the gauges to be deployed at even closer distances.

  16. Specific Phobias

    Science.gov (United States)

    ... Health This information in Spanish ( en español ) Specific phobias Treatment More information on specific phobias A specific ... psychotherapy. Return to top More information on Specific phobias Explore other publications and websites Phobias (Copyright © American ...

  17. Impulse control disorders in Parkinson's disease are associated with dysfunction in stimulus valuation but not action valuation.

    Science.gov (United States)

    Piray, Payam; Zeighami, Yashar; Bahrami, Fariba; Eissa, Abeer M; Hewedi, Doaa H; Moustafa, Ahmed A

    2014-06-01

    A substantial subset of Parkinson's disease (PD) patients suffers from impulse control disorders (ICDs), which are side effects of dopaminergic medication. Dopamine plays a key role in reinforcement learning processes. One class of reinforcement learning models, known as the actor-critic model, suggests that two components are involved in these reinforcement learning processes: a critic, which estimates values of stimuli and calculates prediction errors, and an actor, which estimates values of potential actions. To understand the information processing mechanism underlying impulsive behavior, we investigated stimulus and action value learning from reward and punishment in four groups of participants: on-medication PD patients with ICD, on-medication PD patients without ICD, off-medication PD patients without ICD, and healthy controls. Analysis of responses suggested that participants used an actor-critic learning strategy and computed prediction errors based on stimulus values rather than action values. Quantitative model fits also revealed that an actor-critic model of the basal ganglia with different learning rates for positive and negative prediction errors best matched the choice data. Moreover, whereas ICDs were associated with model parameters related to stimulus valuation (critic), PD was associated with parameters related to action valuation (actor). Specifically, PD patients with ICD exhibited lower learning from negative prediction errors in the critic, resulting in an underestimation of adverse consequences associated with stimuli. These findings offer a specific neurocomputational account of the nature of compulsive behaviors induced by dopaminergic drugs. PMID:24899705

  18. Greater sensitivity to novelty in rats is associated with increased motor impulsivity following repeated exposure to a stimulating environment: implications for the etiology of impulse control deficits.

    Science.gov (United States)

    Ferland, Jacqueline-Marie N; Zeeb, Fiona D; Yu, Katrina; Kaur, Sukhbir; Taves, Matthew D; Winstanley, Catharine A

    2014-12-01

    Heightened motor impulsivity and increased novelty-seeking commonly co-occur in psychiatric disorders, including drug addiction. However, the relationship between these two phenomena remains unclear. One-time tests of novelty sensitivity commonly used in preclinical experiments, such as the open-field or novel-object test, fail to capture the fact that novelty-seekers repeatedly experience novel, stimulating situations. The present study therefore investigated whether repeated exposure to a novel, stimulating environment (SE) altered impulsive action. Male Long-Evans rats were trained to perform the five-choice serial reaction time task (5CSRTT) which measures motor impulsivity in the form of premature responding as well as attention and motivation. Animals were then exposed to a novel SE (1 h/day for 16 days) immediately prior to the 5CSRTT. Significant increases in premature responding were observed in a subgroup of reactive animals termed high responders (HR-SE). These rats were not more impulsive at baseline, and levels of impulsivity normalised once exposure to the SE was discontinued. No other aspect of 5CSRTT performance was affected by the SE challenge. We also determined that HR-SE rats were hyperactive in a novel environment. Biochemical analyses revealed changes in gene and protein expression within the dorsal hippocampus of HR-SE rats, including decreases in mRNA encoding the dopamine D1 receptor and brain-derived neurotrophic factor. These results indicate a novel mechanism by which impulsivity and novelty-reactivity interact that may enhance addiction vulnerability synergistically. Furthermore, studying such context-induced impulsivity may provide insight into the process by which environmental load precipitates psychiatric symptoms in impulse control disorders. PMID:25308904

  19. Chronic Corticosterone Exposure during Adolescence Reduces Impulsive Action but Increases Impulsive Choice and Sensitivity to Yohimbine in Male Sprague-Dawley Rats

    OpenAIRE

    Torregrossa, Mary M.; Xie, Maylene; Taylor, Jane R

    2012-01-01

    Chronic stress during adolescence is associated with an increased risk for alcoholism and addictive disorders. Addiction is also associated with increased impulsivity, and stress during adolescence could alter cortical circuits responsible for response inhibition. Therefore, the present study determined the effect of chronic exposure to the stress hormone corticosterone (CORT) during adolescence on tests of impulsivity in adulthood and examined possible biochemical mechanisms. Male Sprague-Da...

  20. Existence of solutions to second-order boundary-value problems with small perturbations of impulses

    OpenAIRE

    Gabriele Bonanno; Beatrice Di Bella; Johnny Henderson

    2013-01-01

    In this article we study second-order impulsive differential equations with Dirichlet boundary conditions, depending on two real parameters. We show that an appropriate growth condition of the nonlinear term, under small perturbations of impulsive terms, ensures the existence of three solutions. The approach is based on variational methods.

  1. Existence of solutions to second-order boundary-value problems with small perturbations of impulses

    Directory of Open Access Journals (Sweden)

    Gabriele Bonanno

    2013-05-01

    Full Text Available In this article we study second-order impulsive differential equations with Dirichlet boundary conditions, depending on two real parameters. We show that an appropriate growth condition of the nonlinear term, under small perturbations of impulsive terms, ensures the existence of three solutions. The approach is based on variational methods.

  2. Impulsive Choice and Workplace Safety: A New Area of Inquiry for Research in Occupational Settings

    Science.gov (United States)

    Reynolds, Brady; Schiffbauer, Ryan M.

    2004-01-01

    A conceptual argument is presented for the relevance of behavior-analytic research on impulsive choice to issues of occupational safety and health. Impulsive choice is defined in terms of discounting, which is the tendency for the value of a commodity to decrease as a function of various parameters (e.g., having to wait or expend energy to receive…

  3. Quasilinearization for the periodic boundary value problem for systems of impulsive differential equations

    Directory of Open Access Journals (Sweden)

    S. G. Hristova

    2006-01-01

    Full Text Available The method of generalized quasilinearization for the system of nonlinear impulsive differential equations with periodic boundary conditions is studied. As a byproduct, the result for the system without impulses can be obtained, which is a new result as well.

  4. "Speedy Action over Goal Orientation": Cognitive Impulsivity in Male Forensic Patients with Dyslexia

    Science.gov (United States)

    Daderman, Anna M.; Meurling, Ann Wirsen; Levander, Sten

    2012-01-01

    Previous neuropsychiatric studies suggest a relationship between reading disability and cognitive impulsivity. This relationship is not entirely explained by the high comorbidity between reading disability and attention deficit hyperactivity disorder (ADHD), as children with a co-occurrence of these disorders tend to be more impulsive than those…

  5. Practical Stability and Vector-Lyapunov Functions for Impulsive Differential Equations with "Supremum"

    OpenAIRE

    Georgieva, Atanaska; Hristova, Snezhana

    2010-01-01

    Stability of nonlinear impulsive differential equations with "supremum" is studied. A special type of stability, combining two different measures and a dot product on a cone, is defined. Perturbing cone-valued piecewise continuous Lyapunov functions have been applied. Method of Razumikhin as well as comparison method for scalar impulsive ordinary differential equations have been employed.

  6. Lyapunov-Razumikhin method for asymptotic stability of sets for impulsive functional differential equations

    OpenAIRE

    Ivanka M. Stamova; Gani T. Stamov

    2008-01-01

    In the present paper, we study the global stability of sets of sufficiently general type with respect to impulsive functional differential equations with variable impulsive perturbations. The main results are obtained by means of piecewise continuous Lyapunov functions and the use of the Razumikhin technique.

  7. Assessing Inattention and Impulsivity in Children during the Go/NoGo Task

    Science.gov (United States)

    Bezdjian, Serena; Baker, Laura A.; Lozano, Dora Isabel; Raine, Adrian

    2009-01-01

    Behavioural performance in the Go/NoGo task was compared with caregiver and teacher reports of inattention and hyperactivity-impulsivity in 1,151 children (N = 557 boys; N = 594 girls) age 9-10 years old. Errors of commission (NoGo errors) were significantly correlated with symptom counts of hyperactivity-impulsivity, while errors of omission (Go…

  8. Microwave emission from lead zirconate titanate induced by impulsive mechanical load

    Science.gov (United States)

    Aman, A.; Majcherek, S.; Hirsch, S.; Schmidt, B.

    2015-10-01

    This paper focuses on microwave emission from Lead zirconate titanate Pb [ZrxTi1-x] O3 (PZT) induced by mechanical stressing. The mechanical stress was initiated by impact of a sharp tungsten indenter on the upper surface of PZT ceramic. The sequences of microwave and current impulses, which flew from indenter to electric ground, were detected simultaneously. The voltage between the upper and lower surface of ceramic was measured to obtain the behavior of mechanical force acting on ceramic during the impact. It was found that the amplitude, form, and frequency of measured microwave impulses were different by compression and restitution phase of impact. Two different mechanisms of electron emission, responsible for microwave impulse generation, were proposed based on the dissimilar impulse behavior. The field emission from tungsten indenter is dominant during compression, whereas ferroemission dominates during restitution phase. Indeed, it was observed that the direction of the current flow, i.e., sign of current impulses is changed by transitions from compression to restitution phase of impact. The observed dissimilar behavior of microwave impulses, caused by increasing and decreasing applied force, can be used to calculate the contact time and behavior of mechanical force during mechanical impact on ceramic surface. It is shown that the generation of microwave impulses exhibits high reproducibility, impulse intensity, a low damping factor, and high mechanical failure resistance. Based on these microwave emission properties of PZT, the development of new type of stress sensor with spatial resolution of few microns becomes possible.

  9. Family Routine Moderates the Relation between Child Impulsivity and Oppositional Defiant Disorder Symptoms

    Science.gov (United States)

    Lanza, H. Isabella; Drabick, Deborah A. G.

    2011-01-01

    Although child impulsivity is associated with oppositional defiant disorder (ODD) symptoms, few studies have examined whether family processes moderate this association. To address this gap, we tested whether child-reported family routine moderated the relation between child hyperactivity/impulsivity (HI) and ODD symptoms among a sample of…

  10. Impulsivity and Its Relationship to Risky Sexual Behaviors and Drug Abuse

    Science.gov (United States)

    Winters, Ken C.; Botzet, Andria M.; Fahnhorst, Tamara; Baumel, Lindsey; Lee, Susanne

    2009-01-01

    We examined a mediational model of the interrelationship of drug use, sexual risk, and impulsivity in a sample of young adults (N = 89), of which almost half displayed highly disruptive behaviors as children. We chose a mediational model given the emerging evidence that impulsivity is an underlying risk factor for many youth health risk problems,…

  11. The Forms and Functions of Impulsive Actions: Implications for Behavioral Assessment and Therapy

    Science.gov (United States)

    Farmer, Richard F.; Golden, Jeannie A.

    2009-01-01

    Impulsivity is a central defining feature of several psychiatric disorders and a frequent correlate of many forms of psychopathology and maladjustment. Despite recognition of the importance of impulsivity to an understanding of a wide variety of clinically-relevant behaviors, this multifaceted construct remains ill-defined and not well understood.…

  12. Experiment on Impulsive Excitation, Resonance, and Fourier Analysis of a Harmonic Oscillator.

    Science.gov (United States)

    Macomber, Hilliard K.

    1981-01-01

    Describes an electric circuit permitting easy observation and measurement of the response of a damped harmonic oscillator to impulsive excitation. The impulse analysis is carried out and related to experimental observations. The phenomenon of resonance is then interpreted and demonstrated, and through it, contact is made with Fourier analysis.…

  13. Determination of Elastic Moduli of Fiber-Resin Composites Using an Impulse Excitation Technique

    Science.gov (United States)

    Viens, Michael J.; Johnson, Jeffrey J.

    1996-01-01

    The elastic moduli of graphite/epoxy and graphite/cyanate ester composite specimens with various laminate lay-ups was determined using an impulse excitation/acoustic resonance technique and compared to those determined using traditional strain gauge and extensometer techniques. The stiffness results were also compared to those predicted from laminate theory using uniaxial properties. The specimen stiffnesses interrogated ranged from 12 to 30 Msi. The impulse excitation technique was found to be a relatively quick and accurate method for determining elastic moduli with minimal specimen preparation and no requirement for mechanical loading frames. The results of this investigation showed good correlation between the elastic modulus determined using the impulse excitation technique, strain gauge and extensometer techniques, and modulus predicted from laminate theory. The flexural stiffness determined using the impulse excitation was in good agreement with that predicted from laminate theory. The impulse excitation/acoustic resonance interrogation technique has potential as a quality control test.

  14. Extinction and Permanence of a Three-Species Lotka-Volterra System with Impulsive Control Strategies

    Directory of Open Access Journals (Sweden)

    Hunki Baek

    2008-10-01

    Full Text Available A three-species Lotka-Volterra system with impulsive control strategies containing the biological control (the constant impulse and the chemical control (the proportional impulse with the same period, but not simultaneously, is investigated. By applying the Floquet theory of impulsive differential equation and small amplitude perturbation techniques to the system, we find conditions for local and global stabilities of a lower-level prey and top-predator free periodic solution of the system. In addition, it is shown that the system is permanent under some conditions by using comparison results of impulsive differential inequalities. We also give a numerical example that seems to indicate the existence of chaotic behavior.

  15. Dynamics of continuous-time bidirectional associative memory neural networks with impulses and their discrete counterparts

    International Nuclear Information System (INIS)

    This paper is concerned with the global stability characteristics of a system of equations modelling the dynamics of continuous-time bidirectional associative memory neural networks with impulses. Sufficient conditions which guarantee the existence of a unique equilibrium and its exponential stability of the networks are obtained. For the goal of computation, discrete-time analogues of the corresponding continuous-time bidirectional associative memory neural networks with impulses are also formulated and studied. Our results show that the above continuous-time and discrete-time systems with impulses preserve the dynamics of the networks without impulses when we make some modifications and impose some additional conditions on the systems, the convergence characteristics dynamics of the networks are preserved by both continuous-time and discrete-time systems with some restriction imposed on the impulse effect.

  16. Impulsivity and Stillness: NADA, Pharmaceuticals, and Psychotherapy in Substance Use and Other DSM 5 Disorders.

    Science.gov (United States)

    Carter, Kenneth; Olshan-Perlmutter, Michelle

    2015-01-01

    Pharmaceuticals and psychotherapy are commonly used in the management of impulsivity.  The National Acupuncture Detoxification Association (NADA) protocol is an adjunctive therapy that involves the bilateral insertion of 1 to 5 predetermined ear needle points. One of the main benefits reported by patients, providers, and programs utilizing NADA is the sense of stillness, centering, and well-being. The induction of this attitude is seen as contributing to improved clinical outcomes including engagement and retention.  The attitude of stillness is also suggestive of a pathway to mitigating impulsivity. Impulsivity is associated with substance use disorders and other DSM 5 diagnoses.  Impulsivity has characteristics that are manifested clinically in behaviors such as disinhibition, poor self-control, lack of deliberation, thrill seeking, risk-taking. NADA holds promise as a useful treatment adjunct in the comprehensive management of disorders for which impulsivity is a prominent component. PMID:26703743

  17. A COMPARISON OF AGGRESSION AND IMPULSIVITY BETWEEN SMOKERS AND NON-SMOKERS

    Directory of Open Access Journals (Sweden)

    Uzma Zaidi

    2014-12-01

    Full Text Available The study aimed to investigate the role of aggression and impulsivity in smoking among male adult students. It was hypothesized that there would be significant difference between smokers and  non- smokers on the traits of aggression and impulsivity. The sample of two hundred male adult students was selected from different universities of Islamabad. Two subscales of Impulsiveness and Aggression  were administered to measure the personality traits of aggression and impulsivity. Descriptive statistics and  t-test was calculated for analysis of data. Results showed that there is significant differences in aggression and impulsivity between smokers and non-smokers. The result can be helpful for psychologist and other professionals to plan public health therapeutic and social reengineering interventions for youth.

  18. A generalized Halanay inequality on impulsive delayed dynamical systems and its applications

    International Nuclear Information System (INIS)

    Highlights: ? A generalized Halanay differential inequality is derived. ? By using the inequality, we can stabilize an unstable dynamical system via impulses. ? The results are applied to chaos-based secure communication systems. ? The results may develop an effective impulsive control strategy. - Abstract: The main objective of this paper is to extend previous results on Halanay inequality for impulsive delayed dynamical systems. Based on the Razumikhin technique, a generalized Halanay differential inequality on impulsive delayed dynamical systems is analytically established. Compared with some existing works, the distinctive feature of this work is that it can be used to stabilize an unstable delayed dynamical system via impulses. The generalized Halanay inequality may be applied to secure communication systems, and a numerical example is given for illustrating and interpreting the theoretical results.

  19. Use of instant messaging predicts self-report but not performance measures of inattention, impulsiveness, and distractibility.

    Science.gov (United States)

    Levine, Laura E; Waite, Bradley M; Bowman, Laura L

    2013-12-01

    We examined how young adults' use of instant messaging, text messaging, and traditional reading related to their self-reported experience of distractibility and impulsiveness and to their performance on computerized tasks designed to assess inattention and impulsive responses to visual stimuli. Participants reported their media use and completed self-report measures of impulsiveness (i.e., the Barratt Impulsiveness Scale) and distractibility for academic reading. They also completed performance based measures of inattention and impulsiveness using the Tests of Variables of Attention (T.O.V.A.(®)). Results demonstrated that instant message use was significantly related to higher levels of attentional impulsiveness and distractibility on the self-report measures, while traditional reading consistently predicted lower levels of impulsiveness and distractibility. However, media use was not significantly related to the performance measures of inattention and behavioral impulsiveness. PMID:23952624

  20. Examining impulsivity as a moderator of the relationship between body shame and bulimic symptoms in Black and White young women.

    Science.gov (United States)

    Higgins, M K; Lin, Stacy L; Alvarez, Alexandra; Bardone-Cone, Anna M

    2015-06-01

    Impulsivity has been linked to bulimic symptomatology in a number of studies; however, few have examined this relationship among Black women. We investigated the correlations between impulsivity and bulimic symptoms, and tested impulsivity as a moderator of the body shame/bulimic symptoms relationship among a sample of female undergraduates (N=276; 97 Blacks, 179 Whites). These participants provided data on body shame, impulsivity, and bulimic symptoms (EDE-Q binge eating frequency, BULIT-R, EDI-Bulimia). Among Blacks, impulsivity was significantly positively associated with all bulimic symptoms measures; among Whites, impulsivity was only positively correlated with binge eating frequency. Furthermore, among Blacks, the combination of high body shame and high impulsivity was associated with the highest levels of bulimic symptoms; these findings were not observed among Whites. This study highlights the importance of impulsivity and body shame in identifying bulimic symptomatology among Black women. PMID:25867526