WorldWideScience

Sample records for specific impulse magnetoplasma

  1. 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.

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

    Science.gov (United States)

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

    2011-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Science.gov (United States)

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

    2004-11-01

    Decay waves have been observed in the megahertz range in the helium plasma generated by the variable specific impulse magnetoplasma rocket magnetoplasma thruster. They are measured using one of the tips of a triple probe connected to a 50 ? 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.

  5. 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

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

    Science.gov (United States)

    Chavers, Donald Gregory

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

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

    Science.gov (United States)

    Davis, Christopher Nelson

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

  8. 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.

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

    Science.gov (United States)

    Molvig, Kim; Batishchev, Oleg

    2003-01-01

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

  10. Principles of magnetoplasma dynamics

    International Nuclear Information System (INIS)

    A self-contained account is given of magnetoplasma dynamics covering fluid dynamics, thermodynamics, kinetic theory of gases, particle dynamics and electromagnetism. The six chapter headings are, basic concepts, magnetohydrodynamics, dynamics of charged particles, transport in a magnetoplasma, magnetoplasma shock waves, and transport in tokamaks. There are 231 references. (U.K.)

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

    Science.gov (United States)

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

    1992-01-01

    Electric propulsion flight and technology demonstrations conducted in the USA, Europe, Japan, China, and USSR are reviewed with reference to the major flight qualified electric propulsion systems. These include resistojets, ion thrusters, ablative pulsed plasma thrusters, stationary plasma thrusters, pulsed magnetoplasmic thrusters, and arcjets. Evolutionary mission applications are presented for high specific impulse electric thruster systems. The current status of arcjet, ion, and magnetoplasmadynamic thrusters and their associated power processor technologies are summarized.

  12. 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.

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

    Science.gov (United States)

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

    2004-01-01

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

  14. Mission design for Human Outer Planet Exploration (HOPE) using a magnetoplasma spacecraft

    Science.gov (United States)

    Park, Sang-Young; Seywald, Hans; Krizan, Shawn A.; Stillwagen, Frederic H.

    2006-08-01

    To send humans beyond Mars, a Human Outer Planet Exploration (HOPE) mission has been studied for new spacecraft concepts and technologies. In this paper, an interplanetary trajectory and a preliminary spacecraft design are presented for the HOPE visit to Callisto, one of Jupiter's moons. To design a round-trip trajectory for the mission, the characteristics of the spacecraft and its trajectories are analyzed. A detailed optimization approach is formulated to utilize a Variable Specific Impulse Magnetoplasma Rocket (VASIMR) engine with capabilities of variable specific impulse, variable engine efficiency, and engine on-off control. It is mainly illustrated that a 30 MW powered spacecraft can make the mission possible in a 5-year round trip constraint around the year 2045. Trajectories with different power and reactor options are also discussed. The results obtained in this study can be used for formulating an overall concept for the mission.

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

    Science.gov (United States)

    Hoggard, Lindsay; Leahy, Joe

    2009-01-01

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

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

    International Nuclear Information System (INIS)

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

  17. 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.

  18. 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(?) (photopyroelectritermining C(?) (photopyroelectric spectroscopy) to the sub-GHz range.

  19. Specific impulse loss due to friction and dissipation in the nozzle of a liquid propellant rocket engine with film cooling

    Science.gov (United States)

    Lushchik, V. G.; Sizov, V. I.; Sternin, L. E.; Yakubenko, A. E.

    1993-07-01

    A method and algorithms for computing a compressible turbulent boundary layer in the nozzles of liquid propellant rocket engines with film cooling are developed which make it possible to determine losses of the specific impulse due to friction as well as heat fluxes and other flow characteristics. The calculations are based on the numerical solution of gasdynamic equations in the boundary layer approximation using a three-parameter turbulence model. The conditions for minimum specific impulse loss are determined.

  20. 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

  1. 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, aned 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

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

    OpenAIRE

    Bevilacqua, Laura; Doly, Ste?phane; Kaprio, Jaakko; Yuan, Qiaoping; Tikkanen, Roope; Paunio, Tiina; Zhou, Zhifeng; Wedenoja, Juho; Maroteaux, Luc; Diaz, Silvina; Belmer, Arnaud; Hodgkinson, Colin A.; Dell’osso, Liliana; Suvisaari, Jaana; Coccaro, Emil

    2010-01-01

    Impulsivity, describing action without foresight, is an important feature of several psychiatric diseases, suicidality and violent behavior. The complex origins of impulsivity hinder identification of the genes influencing both it and diseases with which it is associated. We performed exon-centric sequencing of impulsive individuals in a founder population, targeting fourteen genes belonging to the serotonin and dopamine domain. A stop codon in HTR2B that is common (MAF >1%) but exclusive to ...

  3. Alfvenic shock waves in a collisional magnetoplasma

    International Nuclear Information System (INIS)

    Compressional Alfvenic shock waves in a cold collisional magnetoplasma are investigated. For this purpose, we use the hydrodynamic equations and Faraday's law to derive the governing nonlinear equations for the compressional Alfven waves. It is shown that the latter can appear in the form of Alfvenic shock waves. -- Highlights: ? We model Alfvenic shock waves in a cold collisional plasma. ? The shock waves appear as monotonic or oscillatory, depending on temporal and spatial scales. ? Can be responsible for cross-field proton acceleration.

  4. TM Waves Propagation at Magnetoplasma-MTMs Interface

    Directory of Open Access Journals (Sweden)

    Rifa J. El-Khozondar

    2012-11-01

    Full Text Available A new structure for isolator is proposed in this work. The proposed structure consists of metamaterial-magnetoplasma semiconductors parallel plate structure. The utility of magnetoplasma semiconductors is promising in developing nonreciprocal components in the submillimeter-wave and millimeter-wave bands for satellite communications. Metamaterials (MTMs is used to enhance the behavior of the isolator.

  5. Tri polar vortices associated with toroidal ion temperature gradient modes in a magnetoplasma with sheared flows

    International Nuclear Information System (INIS)

    A system of nonlinear equations for low-frequency toroidal ion-temperature-gradient modes in a nonuniform magnetoplasma with sheared plasma flow is presented. For some specific profiles of the equilibrium density, the ion temperature and sheared plasma flows, the nonlinear equations admit a tripolar vortex. The numerical results show a negative potential vortex core between the lobs of a dipole-like structure which has a positive value of the potential

  6. Vortex Street in Homogeneous Dense Dusty Magnetoplasma

    Science.gov (United States)

    Yang, Jian-Rong; Wu, Bo; Mao, Jie-Jian; Liu, Ping; Wang, Jian-Yong

    2014-12-01

    For studying the vortex structure in uniform dense dusty astrophysical conditions, a two-dimensional nonlinear equation is derived employing the quantum magnetoplasma hydrodynamic model and considering the strong collisional effect. The coherent vortex solution is obtained by perturbation analysis method. It is shown that the distribution of the electrostatic potential forms spatially a periodic vortex street, and is controlled temporally by the arbitrary function of time that may lead to abundant spacial distributions. It is found that the dust charge number, collision frequency, electron Fermi wavelength and quantum correction all play significant roles to the spatial distribution of vortex street.

  7. Stationary Double Layers in a Collisionless Magnetoplasma

    DEFF Research Database (Denmark)

    Noriyoshi, Sato; Mieno, Tetsu

    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 double layer in the presence of sufficient plasma supply from the plate on the high-potential side.

  8. Electrostatic global vortices in a nonuniform cylindrical magneto-plasma

    International Nuclear Information System (INIS)

    We present nonlinear properties of the low-frequency nonlinear electrostatic waves in a nonuniform bounded magneto-plasma with the equilibrium density and parallel ion velocity gradients along the radial direction. The existence of electrostatic global vortices in a cylindrical magnetoplasma is established. The present results should help to understand the properties of coherent vortical structures in the presence of a magnetic field-aligned ion flow with a radial ion velocity gradient in laboratory magnetoplasmas that are bounded and nonuniform. -- Highlights: ? Sheared flow in bounded cylindrical plasmas. ? Formation of global vortices. ? Inhomogeneous plasma density.

  9. 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.

  10. Instantaneous Impulses.

    Science.gov (United States)

    Erlichson, Herman

    2000-01-01

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

  11. 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...

  12. Impulsive action: Emotional impulses and their control

    Directory of Open Access Journals (Sweden)

    K RichardRidderinkhof

    2014-06-01

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

  13. Impulsive action: emotional impulses and their control.

    Science.gov (United States)

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

    2014-01-01

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

  14. Magneto-Plasma Processes in Relativistic Astrophysics: Modern Developments

    Science.gov (United States)

    Tsupko, Oleg Yu.

    2015-01-01

    This contribution is a review of some talks presented at the session `Magneto-Plasma Processes in Relativistic Astrophysics' of the Thirteenth Marcel Grossmann Meeting MG13. We discuss the modern developments of relativistic astrophysics, connected with presence of plasma and magnetic fields. The influence of magneto-plasma processes on the structure of the compact objects and accretion processes is considered. We also discuss a crucial role of magnetic field for the mechanism of core-collapse supernova explosions. Gravitational lensing in plasma is also considered.

  15. 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)

  16. 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

  17. Surface and bulk magnetoplasma polaritons in the metal-semiconductor-dielectric structure

    International Nuclear Information System (INIS)

    The dispersion properties of bulk and surface magnetoplasma polaritons in the three-layed metal-semiconductor-dielectric structure have been investigated. Resonance interaction of surface magnetoplasma polaritons propagating along two boundaries of the semiconductor layer has been predicted. It is shown that at the definite direction of propagation on the dispersion curves of the surface and bulk magnetoplasma polaritons there are sections with negative dispersion. Accounting of the losses in the semiconductor layer leads to the decomposition of the initial branches of dispersion dependences into the curves of two types, corresponding to direct and backward waves. Non-reciprocal propagation of the bulk magnetoplasma polaritons has been founs

  18. Impulsions attosecondes

    Science.gov (United States)

    Mével, E.; Tcherbakoff, O.; Descamps, D.; Plumridge, J.; Constant, E.

    2003-06-01

    Des expériences récentes ont démontré que les harmoniques d'ordres élevés sont émises sous la forme d'un train d'impulsion attosecondes [1]. Cette découverte ouvre une nouvelle ère en métrologie puisque les échelles de temps sub-femtosecondes auxquelles évoluent les électrons dans les atomes sont désormais accessibles. Cependant, les techniques de type pompelsonde requièrent la sélection préalable d'une seule impulsion attoseconde. Dans cet article, nous présentons et testons une méthode expérimentale permettant de confiner l'émission harmonique en une seule impulsion attoseconde. Nous présentons ensuite quelques techniques de mesure d'impulsions XUV ultra-courtes puis nous suggérons des applications pour la mesure de processus ultra-rapides.

  19. Measurement of plasma parameters in the exhaust of a magnetoplasma rocket by gridded energy analyzer and emissive Langmuir probe

    Science.gov (United States)

    Glover, Timothy Ward

    2002-01-01

    The 10 kilowatt prototype of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) engine, abbreviated as VX-10, is designed to eject plasma at exhaust velocities of tens of kilometers per second. In this device, energy is imparted to the plasma ions by two mechanisms: ion cyclotron resonant heating (ICRH), and acceleration in an ambipolar electric field. Measurements from two different electrostatic probes are combined to determine how much each mechanism contributes to the total ion energy. The first probe is a gridded retarding potential analyzer (RPA) that incorporates a multi-channel collimator to obtain precise measurement of the ion and electron parallel energy distributions. The second is an emissive Langmuir probe that measures the DC and RF components of the plasma potential. The plasma potential obtained from the emitting probe allows calculation of the parallel velocity distribution once the parallel energy distribution is obtained from the energy analyzer data. Biasing the RPA housing is shown to minimize the plasma perturbation, as monitored by an auxiliary probe. When this minimization is done, the RPA measurements become compatible with the emissive probe's measurement of plasma potential. The collimated RPA and emissive probe have been used to examine the effects of a double dual half-turn (DDHT) antenna encircling the plasma. When power at the ion cyclotron frequency is applied, changes are seen in the saturation current and mean ion energy of the collimated RPA characteristic. The evolution of these changes as the RPA is moved downstream from the antenna is interpreted as firm evidence of ion cyclotron heating, albeit at absorbed energies of less than 1 electronvolt per ion. The emissive probe shows that, within experimental error, all of the increased ion energy is accounted for by an increase in the plasma potential that occurs when the ICRF power is applied. The combined RPA and emissive probe data also show that there is a jet of flowing plasma in the VX-10 when operated with the helicon source alone but that the signal from this jet is overwhelmed by a rapidly growing stationary plasma within the first second of the discharge.

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

    International Nuclear Information System (INIS)

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

  1. 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.

  2. Impulsive control for fast nanopositioning

    Science.gov (United States)

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

    2011-04-01

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

  3. Discharge characteristics and dynamics of compressive plasma streams generated by a compact magnetoplasma compressor

    International Nuclear Information System (INIS)

    Results from experimental studies of a compact magnetoplasma compressor designed for operation with heavy gases are presented. The integral characteristics of the discharge and the energy contents and other parameters of the generated xenon plasma streams are determined.

  4. The Current Status of the Magnetoplasma Compressor Device in Belgrade - Study of Plasma Facing Materials Important for Fusion Reactors

    Directory of Open Access Journals (Sweden)

    Nora Trklja

    2015-01-01

    Full Text Available The magnetoplasma compressor, a quasi stationary plasma accelerator, is a source of supersonic compression plasma flow. High plasma parameters of compression flow, large flow velocity and discharge duration enable their efficient usage for development of new plasma technologies, including material surface modification, creation of sub microstructures and nanostructures. In this paper spatial and temporal distribution of emissivity was studied using inverse Abel transform. This has been realized in LabVIEW environment. The plasma flow generated by quasi stationary plasma accelerators can be used for simulation of high energy plasma interaction with different materials of interest for fusion experiments. Surface phenomena are results of specific conditions during plasma flow interaction with target surface. As the next step in our research, spectral analysis of the plasma area around targets surface, after interaction between target and plasma, generated by magnetoplasma compressor, is planned. The first material which will be subjected to interaction with plasma will be a carbon fiber - material of big importance for divertor region in fusion devices.

  5. Thermal Management of Superconducting Electromagnets in VASIMR Thrusters Project

    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...

  6. Optimal control of impulsive Volterra equations with variable impulse times

    CERN Document Server

    Belbas, S A

    2008-01-01

    We obtain necessary conditions of optimality for impulsive Volterra integral equations with switching and impulsive controls, with variable impulse time-instants. The present work continues and complements our previous work on impulsive Volterra control with fixed impulse times.

  7. Temperature effects on the beat heating of a collisional magnetoplasma

    International Nuclear Information System (INIS)

    The beat heating of a magneto-plasma by two antiparallel electromagnetic waves at different temperatures is examined. The effects of plasma temperature, plasma electron collisions, plasma ion collisions and magnitude and direction of the magnetic field on the excitation of plasma electron waves and plasma ion waves are studied. A formula for the power absorption density of the plasma by using Maxwell's equations in conjuction with continuity and momentum equation, including collisions and pressure tensor terms, is derived. The contribution of the plasma temperature to the power absorption density, both at low and high beat frequencies, of the collisional and the noncollisional magnetised plasmas is found very significant and is illustrated numerically. The inclusion of pressure tensor term in the momentum equation is also found to cause characteristic changes in the power absorption density of the plasma with the orientation of magnetic field. (author)

  8. 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.

  9. Evolution of magnetic topology of an erupting arched laboratory magnetoplasma

    Science.gov (United States)

    Tripathi, S.; Gekelman, W. N.

    2013-12-01

    Arched magnetoplasma structures ubiquitously exist in the solar atmosphere and affect energetic phenomena such as flares and coronal mass ejections. Presence of an electrical current in such structures generates a twisted magnetic-field and the term arched magnetic flux rope (AMFR) is used for them. In the limit of low electrical current (compared to the current-threshold for the kink instability), the magnetic twist in an AMFR becomes small and it resembles the structure of an arched magnetic flux tube. However, the term arched magnetic flux rope can be used for arched magnetoplasma structures without any loss of generality. We report results on the evolution of the magnetic topology of an erupting laboratory AMFR during its eruption. The AMFR (plasma ? ? 10-3, Lundquist number ? 102-105, AMFR radius/ion-gyroradius ? 20, B ? 1000 Gauss at footpoints) is created using a lanthanum hexaboride (LaB6) plasma source and it evolves in an ambient magnetoplasma produced by another LaB6 source (See Ref. [2] for details of the experiment). The eruption is triggered by gradually increasing the electrical current in the AMFR and its evolution is captured by a fast-CCD camera. The relative magnitudes of the parameters of the AMFR and the ambient magnetoplasma can be varied to simulate a variety of conditions relevant to solar eruptions. The experiment runs continuously with a 0.5 Hz repetition rate. Hence, the plasma parameters of the AMFR are recorded with a good spatiotemporal resolution (spatial-resolution/AMFR-length ? 10-2 - 10-3, temporal-resolution/eruption-time ? 10-3) using computer-controlled movable probes. The three-dimensional magnetic-field of the AMFR is directly measured using a three-axis magnetic-loop probe. The pre-eruption phase of the AMFR remains quiescent for ? 100 Alfven transit times and the camera images evince a persistent appearance of the AMFR during this phase. In contrast, the post-eruption phase of the AMFR is associated with significant changes in its magnetic topology. Our measurements in the post-eruption phase have identified emergence of magnetic flux ropes from the leading edge of the AMFR and excitation of fast waves and global kink mode oscillations. The main focus of this presentation will be on demonstrating the dramatic changes in the connectivity of the magnetic-field lines of the AMFR during the eruption. Implication of the magnetic-field-line connectivity to the solar AMFR eruptions will also be discussed. References: (1) Tripathi and Gekelman, Phys. Rev. Lett. 105, 075005 (2010) (2) Tripathi and Gekelman, Solar Phys. 286, 479 (2013) (Work performed at Basic Plasma Science Facility, UCLA and supported by US DOE and NSF)

  10. 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.

  11. IMPULSE - advanced nuclear thermal propulsion

    International Nuclear Information System (INIS)

    The IMPULSE nuclear thermal rocket concept provides an evolutionary step toward high thrust-to-weight and specific impulse over a wide operating range. Most of the components and features of the concept are based on demonstrated or proven technology from the NER VA/Rover program. The performance increase is due to the use of a new solid nuclear fuel shape. The new fuel shape provides a large flow area while maintaining flow control and eliminating hot spots due to fuel-to-fuel contact. The control and eliminating hot spots due to fuel-to-fuel contact. The IMPULSE reactor utilizes a multi-pass, series flow configuration to provide excess turbine power while improving the thermal efficiency of the overall system. This configuration also provides a large area for moderator. The IMPULSE concept can provide a specific impulse of up to 1000 seconds and trust to weight ratios approaching 40. The improved performance will reduce the Initial Mass In Low Earth Orbit (IMLEO) and provide a consequent reduction in launch costs and logistics problems

  12. Impulsive action: emotional impulses and their control

    OpenAIRE

    K RichardRidderinkhof; ErikRietveld

    2014-01-01

    This paper presents a novel theoretical view on impulsive action, integrating thus far separate perspectives on nonreflective action, motivation, emotion regulation, and impulse control. We frame impulsive action in terms of directedness of the individual organism towards, away, or against other givens – towards future states and away from one's present state. First, appraisal of a perceived or thought-of event or object on occasion, rapidly and without premonition or conscious deliberat...

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

    Science.gov (United States)

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

    1976-01-01

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

  14. EXCITATION OF KINETIC ALFVEN WAVES BY DENSITY STRIATION IN MAGNETO-PLASMAS

    Energy Technology Data Exchange (ETDEWEB)

    Wu, D. J.; Chen, L., E-mail: clvslc214@pmo.ac.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2013-07-01

    Field-aligned density striation is one of the most common inhomogeneity phenomena in magneto-plasmas, such as in the solar coronal plasma and terrestrial auroral plasma. Kinetic Alfven waves (KAWs) can play an important role in the inhomogeneous heating of coronal magneto-plasmas as well as in the local acceleration of auroral energetic electrons. In this paper, we study the dispersion and instability of KAWs in a magneto-plasma with density striation structures. Results show that KAWs become unstable in the presence of the density striation and the corresponding instability has a maximal growth rate at the perpendicular wavelength close to the spatial scale of the density gradient. Related experimental phenomena in both laboratory and space plasmas are discussed. It is suggested that the excitation of KAWs by the density striation of magneto-plasmas can be of potential importance in understanding the physics of the formation of magneto-plasma filaments and their heating mechanisms, which are often present in the terrestrial auroral plasma, the solar coronal plasma, and other astrophysical plasmas.

  15. Optimization of plasma flow parameters of the magnetoplasma compressor

    International Nuclear Information System (INIS)

    Optimization of the working conditions of the magnetoplasma compressor (MPC) has been performed through analysing discharge and compression plasma flow parameters in hydrogen, nitrogen and argon at different pressures. Energy conversion rate, volt-ampere curve exponent and plasma flow velocities have been studied to optimize the efficiency of energy transfer from the supply source to the plasma. It has been found that the most effective energy transfer from the supply to the plasma is in hydrogen as a working gas at 1000 Pa pressure. It was found that the accelerating regime exists for hydrogen up to 3000 Pa pressures, in nitrogen up to 2000 Pa and in argon up to 1000 Pa pressure. At higher pressures MPC in all the gases works in the decelerating regime. At pressures lower than 200 Pa, high cathode erosion is observed. MPC plasma flow parameter optimization is very important because this plasma accelerating system may be of special interest for solid surface modification and other technology applications

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

    International Nuclear Information System (INIS)

    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.

  17. Effect of ionization energy loss on plasma focus formation in an erosion-type magnetoplasma compressor

    International Nuclear Information System (INIS)

    The equations of radiation magnetogasdynamics, together with the real flow pattern and experimental data, are used to analyze the processes taking place in the plasma focus of a magnetoplasma compressor. It is shown that the energy lost in multiple ionization plays a big role in the energy balance of the plasma in the compression region of an erosion-type magnetoplasma compressor. The mechanisms for energy conversion demonstrated here serve as a guide to ways of controlling the parameters of the plasma focus. 14 references

  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

    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.

  19. Ion Acoustic Waves in an Alkali Magneto-Plasma

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  1. Dopamine, serotonin and impulsivity.

    OpenAIRE

    Dalley, J. W.; Roiser, J. P.

    2012-01-01

    Impulsive people have a strong urge to act without thinking. It is sometimes regarded as a positive trait but rash impulsiveness is also widely present in clinical disorders such as attention deficit hyperactivity disorder (ADHD), drug dependence, mania, and antisocial behaviour. Contemporary research has begun to make major inroads into unravelling the brain mechanisms underlying impulsive behaviour with a prominent focus on the limbic cortico-striatal systems. With this progress has come th...

  2. On the Impulse Control of Jump Diffusions

    CERN Document Server

    Bayraktar, Erhan; Menaldi, Jose-Luis

    2012-01-01

    Regularity of the impulse control problem for a non-degenerate $n$-dimensional jump diffusion with infinite activity and finite variation jumps was recently examined by Davis, Guo, and Wu (SICON 2010). Here we extend the analysis to include infinite activity and infinite variation jumps. More specifically, we show that the value function $u$ of the impulse control problem satisfies $u\\in W^{2,p}_{\\mathrm{loc}}(\\mathbb{R}^{n})$.

  3. Impulsivity and Its Treatment

    Directory of Open Access Journals (Sweden)

    P?nar Güzel Özdemir

    2012-09-01

    Full Text Available Identification, description and therapeutic management of impulsivity, which underlies the mechanism and coexistence of many neurological and psychiatric diseases, are considered to be very crucial. Treatment can be applied in two ways; either for the disorder that occurs with impulsivity or for the treatment of the impulsive behavior itself. Disorders associated with or accompanied by impulsivity can be classified as borderline and antisocial personality disorders, schizophrenia, bipolar disorder, attention deficit and hyperactivity disorder, eating disorders, substance use disorders. In addition, impulsivity can manifest itself within the context of diagnostic criteria implicated in the impulse control disorders which include pathological gambling, intermittent explosive disorder, pyromania, kleptomania and trichotillomania. Behavioral and pharmacological interventions that are effective in treatment plans for these disorders should be integrated. These can be listed as insight-oriented psychotherapy and cognitive-behavioral psychotherapies, contingency management, and pharmacotherapy. The aim of the current review is to understand impulsivity and discuss its relation to other psychiatric disorders and to focus on the treatment of impulsivity.

  4. Non-linear wave interaction in a magnetoplasma column. I - Theory. II Experiment

    Science.gov (United States)

    Larsen, J.-M.; Crawford, F. W.

    1979-01-01

    The paper presents an analysis of non-linear three-wave interaction for propagation along a cylindrical plasma column surrounded either by a metallic boundary, or by an infinite dielectric, and immersed in an infinite, static, axial magnetic field. An averaged Lagrangian method is used and the results are specialized to parametric amplification and mode conversion, assuming an undepleted pump wave. Computations are presented for a magneto-plasma column surrounded by free space, indicating that parametric growth rates of the order of a fraction of a decibel per centimeter should be obtainable for plausible laboratory plasma parameters. In addition, experiments on non-linear mode conversion in a cylindrical magnetoplasma column are described. The results are compared with the theoretical predictions and good qualitative agreement is demonstrated.

  5. Obliquely propagating low frequency electromagnetic shock waves in two dimensional quantum magnetoplasmas

    International Nuclear Information System (INIS)

    Linear and nonlinear propagation characteristics of low frequency magnetoacoustic waves in quantum magnetoplasmas are studied employing the quantum magnetohydrodynamic model. In this regard, a quantum Kadomtsev-Petviashvili-Burgers (KPB) equation is derived using the small amplitude expansion method. The dissipation is introduced by taking into account the kinematic viscosity among the plasma constituents. Furthermore, the solution of KPB equation is presented using the tangent hyperbolic (tanh) method. The variation in the fast and slow magnetoacoustic shock profiles with the quantum Bohm potential via increasing number density, obliqueness angle ?, magnetic field, and the resistivity are also investigated. It is observed that the aforementioned plasma parameters significantly modify the propagation characteristics of nonlinear magnetoacoustic shock waves in quantum magnetoplasmas. The relevance of the present investigation with regard to dense astrophysical environments is also pointed out.

  6. Interactive Effects of Cumulative Stress and Impulsivity on Alcohol Consumption

    Science.gov (United States)

    Fox, Helen C.; Bergquist, Keri L.; Gu, Peihua; Sinha, Rajita

    2013-01-01

    Background Alcohol addiction may reflect adaptations to stress, reward, and regulatory brain systems. While extensive research has identified both stress and impulsivity as independent risk factors for drinking, few studies have assessed the interactive relationship between stress and impulsivity in terms of hazardous drinking within a community sample of regular drinkers. Methods One hundred and thirty regular drinkers (56M/74F) from the local community were assessed for hazardous and harmful patterns of alcohol consumption using the Alcohol Use Disorders Identification Test (AUDIT). All participants were also administered the Barratt Impulsiveness Scale (BIS-11) as a measure of trait impulsivity and the Cumulative Stress/Adversity Checklist (CSC) as a comprehensive measure of cumulative adverse life events. Standard multiple regression models were used to ascertain the independent and interactive nature of both overall stress and impulsivity as well as specific types of stress and impulsivity on hazardous and harmful drinking. Results Recent life stress, cumulative traumatic stress, overall impulsivity, and nonplanning-related impulsivity as well as cognitive and motor-related impulsivity were all independently predictive of AUDIT scores. However, the interaction between cumulative stress and total impulsivity scores accounted for a significant amount of the variance, indicating that a high to moderate number of adverse events and a high trait impulsivity rating interacted to affect greater AUDIT scores. The subscale of cumulative life trauma accounted for the most variance in AUDIT scores among the stress and impulsivity subscales. Conclusions Findings highlight the interactive relationship between stress and impulsivity with regard to hazardous drinking. The specific importance of cumulative traumatic stress as a marker for problem drinking is also discussed. PMID:20491738

  7. Effects of the cannabinoid CB1 receptor antagonist rimonabant on distinct measures of impulsive behavior in rats

    OpenAIRE

    Vries, Taco; Gonzalez-cuevas, Gustavo; Janssen, Mieke; Pattij, Tommy; Schepers, Inga; Schoffelmeer, Anton

    2007-01-01

    Rationale Pathological impulsivity is a prominent feature in several psychiatric disorders, but detailed understanding of the specific neuronal processes underlying impulsive behavior is as yet lacking. Objectives As recent findings have suggested involvement of the brain cannabinoid system in impulsivity, the present study aimed at further elucidating the role of cannabinoid CB1 receptor activation in distinct measures of impulsive behavior. Ma...

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

    Science.gov (United States)

    HAMILTON, KRISTEN R.; ANSELL, EMILY B.; REYNOLDS, BRADY; POTENZA, MARC N.; SINHA, RAJITA

    2013-01-01

    Stress and impulsivity contribute to alcohol use, and stress may also act via impulsivity to increase drinking behavior. Impulsivity represents a multi-faceted construct and self-report and behavioral assessments may effectively capture distinct clinically relevant factors. The present research investigated whether aspects of impulsivity mediate the effect of stress on alcohol use. A community-based sample of 192 men and women was assessed on measures of cumulative stress, alcohol use, self-reported impulsivity, and behavioral choice and response impulsivity. Data were analyzed using regression and bootstrapping techniques to estimate indirect effects of stress on drinking via impulsivity. Cumulative adversity exhibited both direct effects and indirect effects (via self-reported impulsivity) on drinking behavior. Additional models examining specific types of stress indicated direct and indirect effects of trauma and recent life events, and indirect effects of major life events and chronic stressors on drinking behavior. Overall, cumulative stress was associated with increased drinking behavior, and this effect was partially mediated by self-reported impulsivity. Self-reported impulsivity also mediated the effects of different types of stress on drinking behavior. These findings highlight the value of mediation models to examine the pathways through which different types of stress increase drinking behavior. Treatment and prevention strategies should focus on enhancing stress management and self-control. PMID:22376044

  9. Impulsivity and rapid decision-making for reward

    Directory of Open Access Journals (Sweden)

    StephanieBurnett Heyes

    2012-05-01

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

  10. Compression zone of a magnetoplasma compressor as a source of extreme UV radiation

    International Nuclear Information System (INIS)

    Results from experimental studies of extreme UV (EUV) radiation from the compression zone of a magnetoplasma compressor (MPC) operating with xenon are presented. Two MPC operating modes that differ in the method of xenon injection into the discharge were studied. It is shown that EUV radiation in the wavelength range of 5–80 nm is emitted from the compression zone. In the MPC operating mode with local xenon injection directly into the compression zone surrounded by helium plasma, the radiation power reaches it peak value of 16–18 kW in the wavelength range of 12.2–15.8 nm.

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

    International Nuclear Information System (INIS)

    In this work, the phenomenon of formation of localised electrostatic waves (ESWs) 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 several space-based observations.

  12. Choice impulsivity: Definitions, measurement issues, and clinical implications.

    Science.gov (United States)

    Hamilton, Kristen R; Mitchell, Marci R; Wing, Victoria C; Balodis, Iris M; Bickel, Warren K; Fillmore, Mark; Lane, Scott D; Lejuez, C W; Littlefield, Andrew K; Luijten, Maartje; Mathias, Charles W; Mitchell, Suzanne H; Napier, T Celeste; Reynolds, Brady; Schütz, Christian G; Setlow, Barry; Sher, Kenneth J; Swann, Alan C; Tedford, Stephanie E; White, Melanie J; Winstanley, Catharine A; Yi, Richard; Potenza, Marc N; Moeller, F Gerard

    2015-04-01

    Impulsivity critically relates to many psychiatric disorders. Given the multifaceted construct that impulsivity represents, defining core aspects of impulsivity is vital for the assessment and understanding of clinical conditions. Choice impulsivity (CI), involving the preferential selection of smaller sooner rewards over larger later rewards, represents one important type of impulsivity. The International Society for Research on Impulsivity (InSRI) convened to discuss the definition and assessment of CI and provide recommendations regarding measurement across species. Commonly used preclinical and clinical CI behavioral tasks are described, and considerations for each task are provided to guide CI task selection. Differences in assessment of CI (self-report, behavioral) and calculating CI indices (e.g., area-under-the-curve, indifference point, and steepness of discounting curve) are discussed along with properties of specific behavioral tasks used in preclinical and clinical settings. The InSRI group recommends inclusion of measures of CI in human studies examining impulsivity. Animal studies examining impulsivity should also include assessments of CI and these measures should be harmonized in accordance with human studies of the disorders being modeled in the preclinical investigations. The choice of specific CI measures to be included should be based on the goals of the study and existing preclinical and clinical literature using established CI measures. (PsycINFO Database Record PMID:25867841

  13. Impulse radar studfinder

    Science.gov (United States)

    McEwan, T.E.

    1995-10-10

    An impulse radar studfinder propagates electromagnetic pulses and detects reflected pulses from a fixed range. Unmodulated pulses, about 200 ps wide, are emitted. A large number of reflected pulses are sampled and averaged. Background reflections are subtracted. Reflections from wall studs or other hidden objects are detected and displayed using light emitting diodes. 9 figs.

  14. External eating mediates the relationship between impulsivity and unhealthy food intake.

    Science.gov (United States)

    Kakoschke, Naomi; Kemps, Eva; Tiggemann, Marika

    2015-08-01

    Recent evidence from the eating domain shows a link between impulsivity and unhealthy food intake. However, the mechanism underlying this relationship remains unclear. One possibility is an external eating style, which has been linked to both impulsivity and food intake. The current study investigated the potential mediating role of external eating in the relationship between impulsivity and food intake. Participants were 146 undergraduate women who completed measures of impulsivity and external eating, and took part in a laboratory taste test as a behavioural index of unhealthy snack food intake. It was found that attentional and motor impulsivity interacted in predicting sweet food intake, but only motor impulsivity predicted both external eating and sweet food intake. Furthermore, the relationship between motor impulsivity and food intake was mediated by external eating. These findings support the development of interventions aimed at targeting specific aspects of impulsivity in order to reduce unhealthy eating behaviour. PMID:25911264

  15. 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.

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

    Science.gov (United States)

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

    2012-09-01

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

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

    CERN Document Server

    Misra, A P

    2014-01-01

    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 (QMHD) equations, we derive a nonlinear Schr\\"odinger 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 play 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.

  18. 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.

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

    Science.gov (United States)

    Vassileva, Jasmin; Paxton, Jessica; Moeller, F Gerard; Wilson, Michael J; Bozgunov, Kiril; Martin, Eileen M; Gonzalez, Raul; Vasilev, Georgi

    2014-03-01

    The multidimensional construct of impulsivity is implicated in all phases of the addiction cycle. Substance dependent individuals (SDIs) demonstrate elevated impulsivity on both trait and laboratory tests of neurobehavioral impulsivity; however our understanding of the relationship between these different aspects of impulsivity in users of different classes of drugs remains rudimentary. The goal of this study was to assess for commonalities and differences in the relationships between trait and neurobehavioral impulsivity in heroin and amphetamine addicts. Participants included 58 amphetamine dependent (ADIs) and 74 heroin dependent individuals (HDIs) in protracted abstinence. We conducted Principal Component Analyses (PCA) on two self-report trait and six neurobehavioral measures of impulsivity, which resulted in two trait impulsivity (action, planning) and four neurobehavioral impulsivity composites (discriminability, response inhibition efficiency, decision-making efficiency, quality of decision-making). Multiple regression analyses were used to determine whether neurobehavioral impulsivity is predicted by trait impulsivity and drug type. The analyses revealed a significant interaction between drug type and trait action impulsivity on response inhibition efficiency, which showed opposite relationships for ADIs and HDIs. Specifically, increased trait action impulsivity was associated with worse response inhibition efficiency in ADIs, but with better efficiency in HDIs. These results challenge the unitary account of drug addiction and contribute to a growing body of literature that reveals important behavioral, cognitive, and neurobiological differences between users of different classes of drugs. PMID:24342174

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

    International Nuclear Information System (INIS)

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

  1. Impulse Detectors for Noised Sequences

    Directory of Open Access Journals (Sweden)

    R. Lukac

    2001-06-01

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

  2. Impulsive water bells

    Science.gov (United States)

    Antkowiak, Arnaud; Josserand, Christophe; Zaleski, Stéphane; Villermaux, Emmanuel

    2008-11-01

    The impact of a liquid half-sphere located on a falling rigid rod is considered. Following the impact, the drop is strongly deformed into a liquid sheet evolving into the impulsive analogue of Savart's waterbell. We investigate the dynamics of this drop impact model by deriving the initial velocity field within the drop. Interestingly enough, it appears that viscosity plays a major role in the initial development of the liquid film. This behaviour is confirmed by detailed experiments conducted with high-speed video recording and numerical simulations. The subsequent development of the liquid layer, its ejection angle and ultimate formation of the waterbell is considered as well.

  3. Moment methods for solving asymmetrically driven rf probes in the collisional ionospheric magnetoplasma

    International Nuclear Information System (INIS)

    The moment method is discussed, and the application of this method for solving asymmetrically driven RF probes in the collisional and warm ionospheric magnetoplasma is presented. The first three velocity moments of the Boltzmann transport equations are used for the description of the plasma. No interrelation between the electromagnetic mode and the plasma mode is assumed. The effects of these two modes on the antenna impedance are compared and it is shown that the electromagnetic effect is negligible with respect to the plasma effect under certain conditions. The absorptive boundary condition is considered so that the ion sheath may be treated as collapsed. Typical monopole, symmetrical dipole and asymmetrical dipole antennas are considered and many impedance curves are presented. Since the antenna impedance curves are related to all the plasma parameters, the methods of the prediction of plasma parameters from the measured antenna impedances are mentioned. Further research is proposed to eliminate the quasi-static restriction

  4. Electrostatic drift-wave instability in a nonuniform quantum magnetoplasma with parallel velocity shear flows

    International Nuclear Information System (INIS)

    The propagation of high and low frequency (in comparison with the cyclotron frequency) electrostatic drift-waves is investigated in a nonuniform, dense magnetoplasma (composed of electrons and ions), in the presence of parallel shear flow, by employing the quantum magnetohydrodynamic (QMHD) model. Using QMHD model, a new set of equations is presented in order to investigate linear properties of electrostatic drift-waves with sheared plasma flows for dense plasmas. In this regard, dispersion relations for coupled electron-thermal and drift-ion acoustic modes are derived and several interesting limiting cases are discussed. For instance, it is found that sheared ion flow parallel to the external magnetic field can drive the quantum drift-ion acoustic wave unstable, etc. The present investigation may have relevance in dense astrophysical environments where quantum effects are significant.

  5. 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.

  6. Characteristics of plasma streams and optimization of operational regimes for magnetoplasma compressor

    International Nuclear Information System (INIS)

    The main objective of these studies is characterization of dense xenon plasma streams generated by magnetoplasma compressor (MPC) in different operational regimes. Optimization of plasma compression in MPC allows increase of the plasma stream pressure up to 22...25 bar, average temperature of electrons of 10...20 eV and plasma stream velocity varied in the range of (2...9)x106 cm/s depending on operation regime. Spectroscopy measurements demonstrate that in these conditions most of Xe spectral lines are reabsorbed. In the case of known optical thickness, the real value of electron density can be calculated with accounting self-absorption. Estimations of optical thickness were performed and resulting electron density in focus region was evaluated as 1018 cm-3.

  7. Shear driven electromagnetic drift-waves in a nonuniform dense magnetoplasma

    International Nuclear Information System (INIS)

    Linear characteristic properties of high- and low-frequency (in comparison with the cyclotron frequency) electromagnetic drift-waves are studied in a nonuniform, dense magnetoplasma (composed of electrons and ions), in the presence of parallel (magnetic field-aligned) velocity shear, by using quantum magnetohydrodynamic model. By applying the drift-approximation (viz., |? t|cice) to the quantum momentum equations, together with the continuity equations and the Poisson equation, we derive the governing equations for electromagnetic drift-waves with the shear flow. These linear equations are then Fourier transformed to obtain the dispersion relation in both high-frequency and low-frequency regimes. The dispersion relations are then discussed under various limiting cases.

  8. Effects of cumulative stress and impulsivity on smoking status

    Science.gov (United States)

    Ansell, Emily B.; Gu, Peihua; Tuit, Keri; Sinha, Rajita

    2013-01-01

    Objective The stress-vulnerability model of addiction predicts that environmental factors, such as cumulative stress, will result in individual adaptations that decrease self-control, increase impulsivity, and increase risk for addiction. Impulsivity and cumulative stress are risk factors for tobacco smoking that are rarely examined simultaneously in research. Methods We examined the indirect and direct effects of cumulative adversity in a community sample consisting of 291 men and women who participated in an assessment of cumulative stress, self-reported impulsivity, and smoking history. Data were analyzed using bootstrapping techniques to estimate indirect effects of stress on smoking via impulsivity. Results Cumulative adversity is associated with smoking status via direct effects and indirect effects through impulsivity scores. Additional models examining specific types of stress indicate contributions of traumatic stress and recent life events as well as chronic relationship stressors. Conclusions Overall, cumulative stress is associated with increased risk of smoking via increased impulsivity and via pathways independent of impulsivity. These findings support the stress-vulnerability model and highlight the utility of mediation models in assessing how, and for whom, cumulative stress increases risk of current cigarette smoking. Increasing self-control is a target for interventions with individuals who have experienced cumulative adversity. PMID:22389084

  9. Generalized synchronization via impulsive control

    International Nuclear Information System (INIS)

    This paper demonstrates theoretically that two completely different systems can implement GS via impulsive control, moreover by using impulsive control, for a given manifold y = H(x) we construct a response system to achieve GS with drive system and the synchronization manifold is y = H(x). Our theoretical results are supported by numerical examples

  10. 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.

  11. 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.

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

    International Nuclear Information System (INIS)

    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

  13. 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

  14. 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.

  15. 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

  16. Impulse Generation Mechanism in Glycerin Propellant Laser Thruster

    International Nuclear Information System (INIS)

    A sequential process from pulsed laser irradiation onto a spherical liquid propellant to impulse generation is discussed toward higher specific impulse performance of the thruster. A Q-switched 10-ns Nd: YAG laser pulse with 1 ?m wavelength was focused in a 2-mm diameter glycerin droplet in vacuum condition (?10 Pa). Visible image of the droplet shot with the laser pulse, laser energy transmitted through the droplet, emission spectrum in visible to near infrared region, and temporal impulse behavior measured with piezoelectric devices were obtained. It is found that the impulse generation mechanism can be divided into energy deposition on the surface and inside of the droplet, and subsequent explosion of the droplet, depending on laser irradiation conditions

  17. 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...

  18. Ultra-short electromagnetic impulses

    International Nuclear Information System (INIS)

    Ultra-short electromagnetic impulses (USEI) and their interaction with matter are the object of great attention because of their promising applications such as: - the simulation at the laboratory bench scale of astrophysical plasmas or - the development of new ways of accelerating particles that may lead to innovative particle accelerators or - the development of new plasma-laser ray-X sources or - the ignition of thermonuclear reactions. This book is dedicated to USEI, the first chapter begins with the historical aspect of electromagnetic waves and goes on by presenting fundamental physics about wave coherence, laser sources, synchrotron radiation and laser-matter interaction. The second chapter describes the different mathematical tools and analytical methods used in this domain. The third chapter deals more specifically with coherent laser radiation sources and with the interaction of ultra-short high intensity and high power density laser radiation with matter. The last chapter is dedicated to the latest improvements and perspectives in synchrotron radiation source field. (A.C.)

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

    Directory of Open Access Journals (Sweden)

    AlainDervaux

    2010-09-01

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

  20. Pre-attentive information processing and impulsivity in bipolar disorder.

    Science.gov (United States)

    Swann, Alan C; Lijffijt, Marijn; Lane, Scott D; Steinberg, Joel L; Acas, Michelle D; Cox, Blake; Moeller, F Gerard

    2013-12-01

    Early responses to stimuli can be measured by sensory evoked potentials (EP) using repeated identical stimuli, S1 and S2. Response to S1 may represent efficient stimulus detection, while suppression of response to S2 may represent inhibition. Early responses to stimuli may be related to impulsivity. We compared EP reflecting stimulus detection and inhibition in bipolar disorder and healthy controls, and investigated relationships to impulsivity. Subjects were 48 healthy controls without family histories of mood disorder and 48 with bipolar disorder. EP were measured as latencies and amplitudes for auditory P50 (pre-attentional), N100 (initial direction of attention) and P200 (initial conscious awareness), using a paired-click paradigm, with identical stimuli 0.5 s apart. Impulsivity was measured by questionnaire and by laboratory tests for inability to suppress responses to stimuli or to delay response for a reward. Analyses used general linear models. S1 amplitudes for P50, N100, and P200, and gating of N100 and P200, were lower in bipolar disorder than in controls. P50 S1 amplitude correlated with accurate laboratory-task responding, and S2 amplitude correlated with impulsive task performance and fast reaction times, in bipolar disorder. N100 and P200 EP did not correlate with impulsivity. These findings were independent of symptoms, treatment, or substance-use history. EPs were not related to questionnaire-measured or reward-based impulsivity. Bipolar I disorder is characterized by reduced pre-attentional and early attentional stimulus registration relative to controls. Within bipolar disorder, rapid-response impulsivity correlates with impaired pre-attentional response suppression. These results imply specific relationships between ERP-measured response inhibition and rapid-response impulsivity. PMID:24054520

  1. Impulsive phase of solar flares

    Science.gov (United States)

    Kane, S. R.; Crannell, C. J.; Datlowe, D.; Feldman, U.; Gabriel, A.; Hudson, H. S.; Kundu, M. R.; Maetzler, C.; Neidig, D.; Petrosian, V.

    1980-01-01

    The present understanding of the impulsive phase of a solar flare, characterized by short-duration bursts of impulsive hard X-ray, EUV, optical and radio emission indicating the release of energetic electrons is reviewed. Observations of the spectral distribution of impulsive hard X-ray bursts and of Type III and radio continuum bursts are presented and interpreted in terms of energetic electron distributions, and impulsive EUV, XUV, soft X-ray and optical observations, which provide a lower limit to total energy release during the impulsive phase, are discussed. The role of energetic electrons in exciting the hard X-ray, EUV and microwave emissions is considered, and thin-target, thick-target, partial-precipitation and thermal models of impulsive phase electron acceleration are evaluated in light of the observations. It is noted that available data do not allow discrimination between a thermal or a nonthermal electron distribution, on which depends the proportion of flare energy supplied by the energetic electrons, and that data favors models which permit at least partial electron precipitation. Future observational and theoretical work is indicated.

  2. Impulsive phase of solar flares

    International Nuclear Information System (INIS)

    The present understanding of the impulsive phase of a solar flare, characterized by short-duration bursts of impulsive hard X-ray, EUV, optical and radio emission indicating the release of energetic electrons is reviewed. Observations of the spectral distribution of impulsive hard X-ray bursts and of Type III and radio continuum bursts are presented and interpreted in terms of energetic electron distributions, and impulsive EUV, XUV, soft X-ray and optical observations, which provide a lower limit to total energy release during the impulsive phase, are discussed. The role of energetic electrons in exciting the hard X-ray, EUV and microwave emissions is considered, and thin-target, thick-target, partial-precipitation and thermal models of impulsive phase electron acceleration are evaluated in light of the observations. It is noted that available data do not allow discrimination between a thermal or a nonthermal electron distribution, on which depends the proportion of flare energy supplied by the energetic electrons, and that data favors models which permit at least partial electron precipitation. Future observational and theoretical work is indicated

  3. Impulsive nonlocal nonlinear parabolic differential problems

    OpenAIRE

    Ludwik Byszewski

    1993-01-01

    The aim of the paper is to prove a theorem about a weak impulsive nonlinear parabolic differential inequality together with weak impulsive nonlocal nonlinear inequalities. A weak maximum principle for an impulsive nonlinear parabolic differential inequality together with weak impulsive nonlocal nonlinear inequalities and an uniqueness criterion for the existence of the classical solution of an impulsive nonlocal nonlinear parabolic differential problem are obtained as a consequence of the the...

  4. 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.

  5. 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.

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

    International Nuclear Information System (INIS)

    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) × 107 cm/s at the MPC output to ? 6 cm/s in the region of maximum compression and then again increases to 107 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

  7. 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

  8. Three-dimensional current systems and turbulence generation by colliding plasmas in a background magnetoplasma.

    Science.gov (United States)

    Gekelman, W.; Collette, A.; Vincena, S.

    2007-05-01

    Results are presented from an experiment in which two plasmas, initially far denser than a background magnetoplasma (n~ 2× 1012 cm -3 dia ~ 60 cm, L ~ 18m ), collide as they move across the background magnetic field (B = 600 G). The dense plasmas are formed when two laser beams, nearly orthogonal to the background magnetic field strike two carbon targets. The experiment is repeated at 1 Hz and data is acquited at 10 ns intervals and over ten thousand spatial locations. The merging plasmas are observed to carry large diamagnetic currents, which initially shield out most of the background field. A magnetic reconnection event is triggered by the collision and the induced electric field generates a field aligned current, which is the first step in the development of a fully three-dimensional current system. After several ion gyro- periods the current systems become those of shear Alfvèn waves. As local currents move, small reconnection" flares" occur at many locations throughout the plasma volume but they do not seem to affect the overall system dynamics. The data clearly show that the induced electric field is transported though the system by shear Alfvèn waves. The magnetic helicity ?A· B dV is derived from the data and observed to grow with the Alfvèn wave currents and decay on the timescale of the wave magnetic energy. Osscillations in the helicity at the Alfvèn frequency are observed using a wavelet transfomation. Movies and data illustrating the three dimension-spacetime nature of the interaction will be presented.

  9. 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.

  10. 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

  11. Resolving the dispersion relation for a hot magnetoplasma for modes propagating almost perpendicalarly to the magnetic field

    International Nuclear Information System (INIS)

    The aim is to determine the eigenmodes of a warm magnetoplasma which propagates in a direction almost perpendicular to the confining magnetic field. This is done in two ways. First the exact dispersion relation in the complex plane is solved. Secondly, using an approximate equation which is valid for regions outside the vicinity of the cyclotron harmonics, the undamped modes are determined. It can be observed that in cases of almost perpendicular propagation the real high refractive indices previously obtained for perpendicular propagation are still valid. However there is an attenuation of the modes. This damping is calculated

  12. Solar flares - The impulsive phase

    Science.gov (United States)

    Dennis, Brian R.; Schwartz, Richard A.

    1989-01-01

    Only during the previous solar cycle have systematic observations begun to be made with the sensitivity and time resolution, and the continuous coverage required to catch the impulsive phase and measure the rapid variations present in many wavelength ranges. Observations in X-rays, gamma-rays, UV, H-alpha, and radio wavelengths all reveal rapid variations during the impulsive phase and have contributed to our understanding of the different phenomena involved. Results have been obtained from several spacecraft, from rocket and balloon flights, and from groung-based observations. These are reviewed in the context of a simple single loop flare model with a view to showing what results are consistent with this model and what the major problems are in understanding of the impulsive phase.

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

    International Nuclear Information System (INIS)

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

  14. 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

  15. Study on electromagnetic field distribution of impulse current wave

    International Nuclear Information System (INIS)

    The 10/350 ?s impulse current wave which is generated by impulse current generator in the laboratory is simulated by Heidler function current model. Based on dipole theory, electromagnetic field equations are calculated. Combined with Heidler function current model, electromagnetic field time-space distribution of 10/350 ?s impulse current wave is simulated. The results of simulations show that with an increase in the length of the current element, the electromagnetic field intensity, caused by the current element, increases correspondingly. The electromagnetic field caused by the same current element decreases gradually with an increase in the distance. Based on the above conclusions, some electromagnetic protection measures of the laboratory are presented, which have specific meaning to the shield design of the lab and the health of workers in the lab.

  16. 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 ...

  17. Characteristics of Impulsive Suicide Attempts and Attempters.

    Science.gov (United States)

    Simon, Thomas R.; Swann, Alan C.; Powell, Kenneth E.; Potter, Lloyd B.; Kresnow, Marcie-jo; O'Carroll, Patrick W.

    2002-01-01

    Examined impulsive suicide attempts within a population-based, case-control study of nearly lethal suicide attempts among adolescents and young adults. Impulsive attempts were more likely among those who had been in a physical fight and less likely among those who were depressed. Findings suggest inadequate control of aggressive impulses as a…

  18. 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.

  19. Neuroanatomical and Neurochemical Basis of Impulsivity

    Directory of Open Access Journals (Sweden)

    Kemal Yazici

    2010-08-01

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

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

    International Nuclear Information System (INIS)

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

  1. 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.

  2. Effects of Acute Tryptophan Depletion on Three Different Types of Behavioral Impulsivity

    Directory of Open Access Journals (Sweden)

    Donald M. Dougherty

    2010-06-01

    Full Text Available Introduction: While central nervous system serotonin has been implicated in a variety of problematic impulsive behaviors, biological manipulation of brain serotonin using acute tryptophan depletion for studying changes in impulsive behavior has received little attention. Methods: Using identical treatment conditions, we examined the effects of reduced serotonin synthesis for each of three matched groups using acute tryptophan depletion. Thirty healthy men and women (ages 18–45 were assigned to perform one of three tasks assessing different types of behavioral impulsivity: response initiation, response inhibition, and consequence sensitivity (N = 90. Participants completed two experimental days during which each consumed either a tryptophan-depletion or balanced-placebo amino-acid formulation and completed 5 sessions of their respective tasks at 0.25 h before and 1.5, 4.0, 5.0, and 6.0 h after beverage consumption. Results: During peak effectiveness (5.0 h to 6.0 h following amino-acid consumption, depletion produced selective differences dependent on the type of impulsivity being tested. Specifically, relative to baseline testing (pre-depletion, response initiation impulsivity was significantly increased during the peak effects of depletion. And, when compared to placebo control, both response initiation and consequence sensitivity impulsivity were increased during the peak effects of depletion. Conclusion: Though response initiation and consequence sensitivity impulsivity were affected by tryptophan depletion, response inhibition impulsivity was not, suggesting that other biological processes may underlie this specific component of impulsivity. Future research in other populations or using different pharmacological agents is warranted to further examine the biological processes underlying these components of impulsivity.

  3. Review of impulsive phase phenomena

    International Nuclear Information System (INIS)

    A brief review is given of impulsive phase phenomena in support of the models used to compute the energies of the different components of the flares under study. The observational characteristics of the impulsive phase are discussed as well as the evidence for multi-thermal or non-thermal phenomena. The significance of time delays between hard x rays and microwaves is discussed in terms of electron beams and Alfven waves, two-step acceleration, and secondary bursts at large distances from the primary source. Observations indicating the occurrence of chromospheric evaporation, coronal explosions, and thermal conduction fronts are reviewed briefly, followed by the gamma ray and neutron results. Finally, a preferred flare scenario and energy source are presented involving the interactions in a complex of magnetic loops with the consequent reconnection and electron acceleration

  4. The Impulse-Radiating Antenna

    OpenAIRE

    Rosenlind, Johanna

    2009-01-01

    As the interest in intentional electromagnetic interference (IEMI) increases, so does the need of a suitable antenna which endures those demanding conditions. The ultrawideband (UWB) technology provides an elegant way of generating high-voltage UWB pulses which can be used for IEMI. One UWB antenna, invented solely for the purpose of radiating pulses, is the impulse radiating antenna (IRA). In the course of this master thesis work, a suitable geometry of the IRA is suggested, and modelled, fo...

  5. 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

  6. 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

  7. 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)

  8. Electrodynamic Characteristics of a Strip Antenna Located on a Plane Interface of a Resonant Magnetoplasma and an Isotropic Medium

    Science.gov (United States)

    Zaboronkova, T. M.; Zaitseva, A. S.; Kudrin, A. V.; Spagnolo, B.

    2015-04-01

    We study the electrodynamic characteristics of an antenna having the form of an infinitesimally thin, perfectly conducting narrow strip located on a plane interface of a resonant magnetoplasma and an isotropic medium. The antenna is perpendicular to an external magnetic field and is excited by a given voltage. Singular integral equations for the antenna current, on the basis of which the current distribution is found in the case of an infinitely long radiator, are obtained. The limits of applicability of an approximate method based on the transmission line theory for determining the current distribution and input impedance of the antenna are established. Within the framework of this method, the results obtained are generalized to the case of a finite-length strip antenna.

  9. Energy losses by a charged particle moving through a magnetoplasma in the presence of high frequency external electrical field

    International Nuclear Information System (INIS)

    The problem of amplification and suppression of natural high frequency Langmuir oscillations excited by the charged particles passing through the magnetoplasma placed in an external high frequency electric field has been studied. It has been found that in the absence of the magnetic field, for weak high frequency electric field the excited Langmuir oscillations grow in amplitude whereas in the presence of strong high frequency field the Langmuir oscillations are suppressed. The inclusion of external static magnetic field leads to the excitation of upper hybrid frequency. The excited upper hybrid waves are amplified when the oscillating high frequency electric field is weak in intensity and they are damped when the high frequency electric field is strong. The analytical expressions for the polarisation loss under various conditions have been obtained. (auth.)

  10. 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)

  11. 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.

  12. Managing Impulsive Interference in Impulse Radio UWB Networks

    OpenAIRE

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

    2007-01-01

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

  13. A Review of Impulse Buying Behavior

    Directory of Open Access Journals (Sweden)

    G. Muruganantham

    2013-04-01

    Full Text Available 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 journal databases and books were referred to review the worksof various researchers. The content analysis of the various research works led to the classification of literatureinto different factors influencing impulse buying and further development of research framework. The multipleaspects of the subject are categorized for future research works in the area of impulse buying with thesuggestions. The paper will be useful for marketing practitioners and researchers towards comprehensiveunderstanding of the consumer’s impulsiveness.  

  14. Impulsive control and synchronization of spatiotemporal chaos

    International Nuclear Information System (INIS)

    The impulsive control of spatiotemporal chaos of a particular type of non-linear partial differential equations has been investigated. A criterion for the solutions of these partial differential equations to be equi-attractive in the large is determined and an estimate for the basin of attraction is given in terms of the impulse durations and the magnitude of the impulses. Extending these results to impulsively synchronize spatiotemporal chaos of the same type of partial differential equations is explored. A proof for the existence of a certain kind of impulses for synchronization such that the error dynamics is equi-attractive in the large, is established. A comparison of the developed theoretical model with other existent numerical models available in the literature has been studied. Several simulation results are given to confirm the theoretical results. Moreover, an investigation of the Lyapunov exponents of the error dynamics between impulsively synchronized spatiotemporal chaotic systems, is done to further confirm the theoretical results

  15. Does mother know best? Adolescent and mother reports of impulsivity and subsequent delinquency.

    Science.gov (United States)

    Bechtold, Jordan; Cavanagh, Caitlin; Shulman, Elizabeth P; Cauffman, Elizabeth

    2014-11-01

    Although impulsivity is one of the strongest psychological predictors of crime, it is unclear how well impulsivity, measured at a specific moment in adolescence, predicts criminal behavior months or years into the future. The present study investigated how far into the future self-reports and parents' reports of a youth's impulsivity predicted whether he engaged in illegal behavior, whether one reporter's assessment was more predictive than the other's, and whether there is value in obtaining multiple reports. Data were obtained from a 6-year longitudinal study of adjudicated juvenile offenders (n = 701 mother-son dyads). Youth (m = 15.93 years old; sd = 1.14) and their mothers independently reported on adolescents' impulsivity at the initial assessment. We examined the prospective correlation of these measures with illegal behavior, assessed by official records of arrests and youths' self-reports of offending across the 72-month study period. Youths' and mothers' reports of the adolescents' impulsivity were weakly, but significantly, correlated with one another. Furthermore, mothers' ratings of their sons' impulsivity predicted arrest up to 6 years into the future, whereas youths' reports did not significantly predict arrest beyond 30 months. With respect to youths' self-reports of offending, mothers' ratings of impulsivity again predicted farther into the future (as late as 6 years later) than did youths' self-reports of impulsivity, which were not predictive beyond 4 years. However, across the first 4 years, youths' self-reports of impulsivity explained more variance in self-reported offending than did mothers' ratings. The results underscore the endurance of the predictive utility of an assessment of impulsivity and the importance (and accuracy) of parents' reports of developmental constructs, even when their children are adolescents. PMID:24337690

  16. 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...

  17. Optimal Control of Volterra Equations with Impulses

    OpenAIRE

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

    2004-01-01

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

  18. 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...

  19. Chaotification of complex networks with impulsive control

    Science.gov (United States)

    Guan, Zhi-Hong; Liu, Feng; Li, Juan; Wang, Yan-Wu

    2012-06-01

    This paper investigates the chaotification problem of complex dynamical networks (CDN) with impulsive control. Both the discrete and continuous cases are studied. The method is presented to drive all states of every node in CDN to chaos. The proposed impulsive control strategy is effective for both the originally stable and unstable CDN. The upper bound of the impulse intervals for originally stable networks is derived. Finally, the effectiveness of the theoretical results is verified by numerical examples.

  20. 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

  1. 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.

  2. 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

  3. The Relationship between Impulsive Choice and Impulsive Action: A Cross-Species Translational Study

    OpenAIRE

    Broos, N.; Schmaal, L.; Wiskerke, J.; Kostelijk, L.; Lam, T.; Stoop, N.; Weierink, L.; Ham, J.; Geus, E. J. C.; Schoffelmeer, A. N. M.; Brink, W. Den; Veltman, D. J.; Vries, T. J.; Pattij, T.; Goudriaan, A. E.

    2012-01-01

    Maladaptive impulsivity is a core symptom in various psychiatric disorders. However, there is only limited evidence available on whether different measures of impulsivity represent largely unrelated aspects or a unitary construct. In a cross-species translational study, thirty rats were trained in impulsive choice (delayed reward task) and impulsive action (five-choice serial reaction time task) paradigms. The correlation between those measures was assessed during baseline performance and aft...

  4. Test-retest reliability of behavioral measures of impulsive choice, impulsive action, and inattention

    OpenAIRE

    Weafer, Jessica; Baggott, Matthew J.; Wit, Harriet

    2013-01-01

    Behavioral measures of impulsivity are widely used in substance abuse research, yet relatively little attention has been devoted to establishing their psychometric properties, especially their reliability over repeated administration. The current study examined the test-retest reliability of a battery of standardized behavioral impulsivity tasks, including measures of impulsive choice (delay discounting, probability discounting, and the Balloon Analogue Risk Task), impulsive action (the stop ...

  5. Synthesis of Room Impulse Responses for Variable Source Characteristics

    OpenAIRE

    M. Kunkemoeller; Dietrich, P.; M. Pollow

    2011-01-01

    Every acoustic source, e.g. a speaker, a musical instrument or a loudspeaker, generally has a frequency dependent characteristic radiation pattern, which is preeminent at higher frequencies. Room acoustic measurements nowadays only account for omnidirectional source characteristics. This motivates a measurement method that is capable of obtaining room impulse responses for these specific radiation patterns by using a superposition approach of several measurements with technically well-defined...

  6. Impulse control disorders in Parkinson's disease: clinical characteristics and implications

    OpenAIRE

    Leeman, Robert F.; Potenza, Marc N.

    2011-01-01

    Impulse control disorders (ICDs), specifically those related to excessive gambling, eating, sex and shopping, have been observed in a subset of people with Parkinson's disease (PD). Although some initial case reports claimed that dopamine replacement therapies, particularly dopamine agonists, cause ICDs, more recent, larger and better controlled studies indicate a more complicated picture. While dopamine replacement therapy use is related to ICDs, other vulnerabilities, some related to PD and...

  7. RFI mitigation at Nanc¸ay Observatory: Impulsive Signal Processing

    OpenAIRE

    Ait-Allal, Dalal; Dumez-viou, Cedric; Weber, Rodolphe; Desvignes, Grégory; Cognard, Ismael; Theureau, Gilles

    2010-01-01

    Radio astronomy has protected frequency bands for free observations. However, it is often necessary to observe outside of those sanctuaries. For example, it is the case for HI radio-sources with high red-shifts that are observed into radarallocated frequency bands. A radar pulse blanker based on statistical analysis has been implemented in a FPGA. Several tricks has made the implementation possible at a low hardware cost. Pulsar is another kind of impulsive signal which needs specific process...

  8. Transient Impulsive Electronic Raman Redistribution

    Science.gov (United States)

    Miyabe, S.; Bucksbaum, P.

    2015-04-01

    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 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.

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

    Science.gov (United States)

    Cyders, Melissa A.

    2013-01-01

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

  10. 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...

  11. Stabilization of a Class of Nonlinear Systems using State-dependent Switching Control and Impulsive Control

    Science.gov (United States)

    Stechlinski, Peter; Liu, Xinzhi

    2011-11-01

    This paper develops a hybrid control strategy for stabilizing a class of nonlinear systems using switching and impulsive control. More specifically, some easily verifiable conditions are developed which guarantee the exponential stability of a class of switched and impulsive nonlinear systems under a particular state-dependent switching rule. The main result is proved using a common Lyapunov function. An illustrating example is given with a simulation.

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

    OpenAIRE

    Robinson, T. R.

    2002-01-01

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

  13. Plasma wave instabilities as inverse anderson localization: magnetoplasma Bernstein mode-drift wave and Bernstein mode-ion acoustic wave hybridization

    International Nuclear Information System (INIS)

    Plasma wave instabilities via wave-wave coupling are argued to be a form of inverse Anderson localization in the Siegel generalized-disorder collective-boson modesoftening universality-principle (GDCBMSUP). In particular, magnetoplasma Bernstein cyclotron modedrift wave and magnetoplasma Bernstein cyclotron mode-ion acoustic wave hybridization instabilities, whether growing or decaying in amplitude, are viewed as stopping-band formation in wavevector and/or energy(frequency) in the scatterer dispersion dispersion relation with hybridization induced density of states energy(frequency) gap formation due to isotropic backscattering in the scatteree dispersion relation. This isotropic backscattering of scatteree(positive group velocity) wave by scatterer(negative group velocity) wave at an up-down crossing in plasma wave dispersion relation produces a Mott-Hubbard gap in the scatteree plasma wave density of states in which scatteree plasma wave pass-band tails exponentially decay into the scatteree stopping-band gap in space and/or time. It is seen that a magnetoplasma Bernstein cyclotron mode experiences a drift wave or an ion acoustic wave (or even a deviation of its propagation angle from normal to the applied magnetic field direction) as generalized-disorder symmetry-breaking, and is thus driven to mode-soften with negative-dispersion via hybridization with the other (scatteree) plasma wave, yielding the negative group velocity stopping band in wavevector and energy(fy stopping band in wavevector and energy(frequency)

  14. 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…

  15. [Neurochemistry of impulsiveness and aggression].

    Science.gov (United States)

    Vetulani, Jerzy

    2013-01-01

    Aggression is the most frequent social reaction among animals and men, and plays an important role in survival of the fittest. The change of social conditions in the course of development of human civilisation rendered some forms of aggression counter-adaptive, but the neurobiological mechanism of expression of aggression have not fundamentally changed in the last stages of human evolution. The two different kinds of aggression: emotional, serving mainly as a threat, and rational, predatory, serving for the attainment of goal in the most effective way, have different anatomical and neurobiological background and reciprocally inhibit each other. Aggression is modulated by several neurotransmitter and hormonal systems, of which the key role is seemingly played by testosterone, a hormone involved in domination behaviour, and serotonin, whose deficit results in increased impulsiveness. PMID:23888748

  16. 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...

  17. An electret transducer for impulse voltage measurements

    International Nuclear Information System (INIS)

    It is known that lightning produces impulse voltages and currents in transmission and distribution lines. A low-cost method for measuring peak currents is to use devices such as magnetic links and magnetic tapes. In this paper, a new method for detecting impulse voltages that uses an electret as the element of transduction is proposed. The new sensor consists of two metallic electrodes separated by a piece of dielectric (Teflon FEP) and an air gap. The impulse voltage produces an electric discharge in the gap and charges are transferred from the electrode to the dielectric surface, forming the electret

  18. Borehole induction transmitter of electrical impulses

    Energy Technology Data Exchange (ETDEWEB)

    Vorob' ev, Yu.A.; Grigor' yan, B.N.

    1963-04-17

    This borehole induction transmitter of electrical impulses is hermetically sealed in an elongated body. For safety during lowering-hoisting operations, and for detonating explosives in the well, the device is made in the form of a multilayer coil (a solenoid), on the end of which a magnet is suspended by means of a spiral spring. An electrical impulse activates the solenoid and spring, causing the magnet to make electrical contact for detonating perforators or in well shooting. This spring also serves to dampen the vibrations following each thrust or impulse of the system.

  19. Spin Stabilized Impulsively Controlled Missile (SSICM)

    Science.gov (United States)

    Crawford, J. I.; Howell, W. M.

    1985-12-01

    This patent is for the Spin Stabilized Impulsively Controlled Missile (SSICM). SSICM is a missile configuration which employs spin stabilization, nutational motion, and impulsive thrusting, and a body mounted passive or semiactive sensor to achieve very small miss distances against a high speed moving target. SSICM does not contain an autopilot, control surfaces, a control actuation system, nor sensor stabilization gimbals. SSICM spins at a rate sufficient to provide frequency separation between body motions and inertial target motion. Its impulsive thrusters provide near instantaneous changes in lateral velocity, whereas conventional missiles require a significant time delay to achieve lateral acceleration.

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

    Directory of Open Access Journals (Sweden)

    Aleksandra Krasowska,

    2013-07-01

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

  1. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-11-15

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Giovannini, A. Z.; Barendregt, I.; Haslinde, T.; Hubbs, C.; Abhari, R. S.

    2015-04-01

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

  5. Stochastic impulsive control for the stabilization of Lorenz system

    Science.gov (United States)

    Wang, Liang; Zhao, Rui; Xu, Wei; Zhang, Ying

    2011-02-01

    This paper derives some sufficient conditions for the stabilization of Lorenz system with stochastic impulsive control. The estimate of the upper bound of impulse interval for asymptotically stable control is obtained. Some differences between the system with stochastic impulsive control and with deterministic impulsive control are presented. Computer simulation is given to show the effectiveness of the proposed method.

  6. Impulsive waves in the Nariai universe

    International Nuclear Information System (INIS)

    A new class of exact solutions is presented which describes impulsive waves propagating in the Nariai universe. It is constructed using a six-dimensional embedding formalism adapted to the background. Because of the topology of the latter, the wave front consists of two nonexpanding spheres. Special subclasses representing pure gravitational waves (generated by null particles with an arbitrary multipole structure) or shells of null dust are analyzed in detail. Smooth isometries of the metrics are briefly discussed. Furthermore, it is shown that the considered solutions are impulsive members of a more general family of radiative Kundt spacetimes of type II. A straightforward generalization to impulsive waves in the anti-Nariai and Bertotti-Robinson backgrounds is described. For a vanishing cosmological constant and electromagnetic field, results for well known impulsive pp waves are recovered

  7. Synchronization of impulsively coupled complex networks

    International Nuclear Information System (INIS)

    We investigate the synchronization of complex networks, which are impulsively coupled only at discrete instants. Based on the comparison theory of impulsive differential systems, a distributed impulsive control scheme is proposed for complex dynamical networks to achieve synchronization. The proposed scheme not only takes into account the influence of all nodes to network synchronization, which depends on the weight of each node in the network, but also provides us with a flexible method to select the synchronized state of the network. In addition, it is unnecessary for the impulsive coupling matrix to be symmetrical. Finally, the proposed control scheme is applied to a chaotic Lorenz network and Chua's circuit network. Numerical simulations are used to illustrate the validity of this control scheme. (general)

  8. Chronic Gambling Linked to Depression, Impulsivity

    Science.gov (United States)

    ... nih.gov/medlineplus/news/fullstory_152761.html Chronic Gambling Linked to Depression, Impulsivity Both should be treated ... were more likely to gamble later in life. "Gambling problems may be more a personal problem similar ...

  9. Feedback linearization of impulsive nonlinear control systems

    Science.gov (United States)

    Menini, L.; Tornambè, A.

    2012-09-01

    The goal of this paper is to extend to nonlinear impulsive control systems the necessary and sufficient conditions for feedback linearization recently developed for purely continuous-time nonlinear systems.

  10. 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.

  11. 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 ry is not restricted to loops but applied equally to open field regions

  12. Probing compulsive and impulsive behaviors, from animal models to endophenotypes: a narrative review.

    Science.gov (United States)

    Fineberg, Naomi A; Potenza, Marc N; Chamberlain, Samuel R; Berlin, Heather A; Menzies, Lara; Bechara, Antoine; Sahakian, Barbara J; Robbins, Trevor W; Bullmore, Edward T; Hollander, Eric

    2010-02-01

    Failures in cortical control of fronto-striatal neural circuits may underpin impulsive and compulsive acts. In this narrative review, we explore these behaviors from the perspective of neural processes and consider how these behaviors and neural processes contribute to mental disorders such as obsessive-compulsive disorder (OCD), obsessive-compulsive personality disorder, and impulse-control disorders such as trichotillomania and pathological gambling. We present findings from a broad range of data, comprising translational and human endophenotypes research and clinical treatment trials, focussing on the parallel, functionally segregated, cortico-striatal neural projections, from orbitofrontal cortex (OFC) to medial striatum (caudate nucleus), proposed to drive compulsive activity, and from the anterior cingulate/ventromedial prefrontal cortex to the ventral striatum (nucleus accumbens shell), proposed to drive impulsive activity, and the interaction between them. We suggest that impulsivity and compulsivity each seem to be multidimensional. Impulsive or compulsive behaviors are mediated by overlapping as well as distinct neural substrates. Trichotillomania may stand apart as a disorder of motor-impulse control, whereas pathological gambling involves abnormal ventral reward circuitry that identifies it more closely with substance addiction. OCD shows motor impulsivity and compulsivity, probably mediated through disruption of OFC-caudate circuitry, as well as other frontal, cingulate, and parietal connections. Serotonin and dopamine interact across these circuits to modulate aspects of both impulsive and compulsive responding and as yet unidentified brain-based systems may also have important functions. Targeted application of neurocognitive tasks, receptor-specific neurochemical probes, and brain systems neuroimaging techniques have potential for future research in this field. PMID:19940844

  13. Anger and Impulsivity in Adolescents Attempting Suicide

    OpenAIRE

    Elif AKIN; Berkem, Meral

    2012-01-01

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

  14. Impulse control problem with switching technology

    CERN Document Server

    Amami, Rim

    2010-01-01

    We consider an impulse control problem in infinite horizon applied with switching technology. We suppose that the firm decides at certain moments (impulse moments) to switch technology, leading to a jump of the firm value. We show that the value function for such problems satisfies a dynamic programming principle version. Our objective is to look for an optimal strategy which maximizes the value function associated with a switching problem.

  15. Outer Synchronization of Complex Networks by Impulse

    International Nuclear Information System (INIS)

    This paper investigates outer synchronization of complex networks, especially, outer complete synchronization and outer anti-synchronization between the driving network and the response network. Employing the impulsive control method which is uncontinuous, simple, efficient, low-cost and easy to implement in practical applications, we obtain some sufficient conditions of outer complete synchronization and outer anti-synchronization between two complex networks. Numerical simulations demonstrate the effectiveness of the proposed impulsive control scheme. (general)

  16. 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...

  17. ADHD-hyperactive/impulsive subtype in adults

    OpenAIRE

    FARAONE, STEPHEN V.; Jeanne M. Landgraf; Hodgkins, Paul S.; Goodman, David W.; Christopher Gibbins; Weiss, Margaret D

    2010-01-01

    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 hea...

  18. 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

  19. 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

  20. Impulsive control and synchronization of the Lorenz systems family

    International Nuclear Information System (INIS)

    In this paper, impulsive control and synchronization for the newly presented Lorenz systems family are systematically investigated. Some new and more comprehensive criteria for global exponential stability and asymptotical stability of impulsively controlled Lorenz systems family are established with varying impulsive intervals. In particular, several simple and easily verified criteria are derived with equivalent impulsive intervals. An illustrative example is also provided to show the effectiveness and feasibility of the impulsive control method

  1. Differential associations between impulsivity and risk-taking and brain activations underlying working memory in adolescents.

    Science.gov (United States)

    Panwar, Karni; Rutherford, Helena J V; Mencl, W Einar; Lacadie, Cheryl M; Potenza, Marc N; Mayes, Linda C

    2014-11-01

    Increased impulsivity and risk-taking are common during adolescence and relate importantly to addictive behaviors. However, the extent to which impulsivity and risk-taking relate to brain activations that mediate cognitive processing is not well understood. Here we examined the relationships between impulsivity and risk-taking and the neural correlates of working memory. Neural activity was measured in 18 adolescents (13-18 years) while they engaged in a working memory task that included verbal and visuospatial components that each involved encoding, rehearsal and recognition stages. Risk-taking and impulsivity were assessed using the Balloon Analogue Risk Task (BART) and the adolescent version of the Barratt Impulsiveness Scale-11 (BIS-11A), respectively. We found overlapping as well as distinct regions subserving the different stages of verbal and visuospatial working memory. In terms of risk-taking, we found a positive correlation between BART scores and activity in subcortical regions (e.g., thalamus, dorsal striatum) recruited during verbal rehearsal, and an inverse correlation between BART scores and cortical regions (e.g., parietal and temporal regions) recruited during visuospatial rehearsal. The BIS-11A evidenced that motor impulsivity was associated with activity in regions recruited during all stages of working memory, while attention and non-planning impulsivity was only associated with activity in regions recruited during recognition. In considering working memory, impulsivity and risk-taking together, both impulsivity and risk-taking were associated with activity in regions recruited during rehearsal; however, during verbal rehearsal, differential correlations were found. Specifically, positive correlations were found between: (1) risk-taking and activity in subcortical regions, including the thalamus and dorsal striatum; and, (2) motor impulsivity and activity in the left inferior frontal gyrus, insula, and dorsolateral prefrontal cortex. Therefore these findings suggest that while there may be some overlap in the neural correlates of working memory and their relationship to impulsivity and risk-taking, there are also important differences in these constructs and their relationship to the stages of working memory during adolescence. PMID:24582821

  2. Controlling your impulses: electrical stimulation of the human supplementary motor complex prevents impulsive errors.

    Science.gov (United States)

    Spieser, Laure; van den Wildenberg, Wery; Hasbroucq, Thierry; Ridderinkhof, K Richard; Burle, Borís

    2015-02-18

    To err is human. However, an inappropriate urge does not always result in error. Impulsive errors thus entail both a motor system capture by an urge to act and a failed inhibition of that impulse. Here we show that neuromodulatory electrical stimulation of the supplementary motor complex in healthy humans leaves action urges unchanged but prevents them from turning into overt errors. Subjects performed a choice reaction-time task known to trigger impulsive responses, leading to fast errors that can be revealed by analyzing accuracy as a function of poststimulus time. Yet, such fast errors are only the tip of the iceberg: electromyography (EMG) revealed fast subthreshold muscle activation in the incorrect response hand in an even larger proportion of overtly correct trials, revealing covert response impulses not discernible in overt behavior. Analyzing both overt and covert response tendencies enables to gauge the ability to prevent these incorrect impulses from turning into overt action errors. Hyperpolarizing the supplementary motor complex using transcranial direct current stimulation (tDCS) preserves action impulses but prevents their behavioral expression. This new combination of detailed behavioral, EMG, and tDCS techniques clarifies the neurophysiology of impulse control, and may point to avenues for improving impulse control deficits in various neurologic and psychiatric disorders. PMID:25698738

  3. 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

  4. Selective cocaine-related difficulties in emotional intelligence: relationship to stress and impulse control.

    Science.gov (United States)

    Fox, Helen C; Bergquist, Keri L; Casey, James; Hong, K Adam; Sinha, Rajita

    2011-01-01

    Emotional Intelligence (EI) comprises the ability to perceive, use, understand, and regulate emotions and may potentially contribute to variability in risk-related factors such as stress perception and impulse control in cocaine dependent individuals. The main objective of the current study is to better define EI in cocaine dependent individuals compared with healthy controls, using the Mayer, Salovey, and Caruso Emotional Intelligence Test (MSCEIT). Secondary analysis investigates the association between EI, IQ factors, perceived stress, and impulse control in both populations. Seventy-two abstinent treatment-seeking cocaine patients and 52 healthy controls were administered the MSCEIT as well as measures of IQ, perceived stress, and impulse control. Findings showed that cocaine dependent participants demonstrated highly selective EI difficulties compared with healthy controls, specifically with regard to higher-level emotional reasoning including the understanding, management, and regulation of emotion. These EI problems were associated with increased perceived stress and impulse control difficulties. IQ was significantly associated with all MSCEIT measures in the cocaine dependent participants, but not controls. Findings indicate that specific aspects of EI may be of clinical importance to cocaine dependent populations, impacting relapse-related factors such as stress dysregulation and impulse control.? PMID:21314758

  5. Selective Cocaine-Related Difficulties in Emotional Intelligence: Relationship to Stress and Impulse Control

    Science.gov (United States)

    Fox, Helen C.; Bergquist, Keri L.; Casey, James; Hong, K. Adam; Sinha, Rajita

    2010-01-01

    Emotional Intelligence (EI) comprises the ability to perceive, use, understand and regulate emotions and may potentially contribute to variability in risk-related factors such as stress perception and impulse control in cocaine dependent individuals. The main objective of the current study is to better define EI in cocaine dependent individuals compared with healthy controls, using the Mayer, Salovey, and Caruso Emotional Intelligence Test (MSCEIT1). Secondary analysis investigates the association between EI, IQ factors, perceived stress and impulse control in both populations. Seventy-two abstinent treatment-seeking cocaine patients and 52 healthy controls were administered the MSCEIT as well as measures of IQ, perceived stress and impulse control. Findings showed that cocaine dependent participants demonstrated highly selective EI difficulties compared with healthy controls, specifically with regard to higher level emotional reasoning including the understanding, management and regulation of emotion. These EI problems were associated with increased perceived stress and impulse control difficulties. IQ was significantly associated with all MSCEIT measures in the cocaine dependent participants, but not controls. Findings indicate that specific aspects of EI may be of clinical importance to cocaine dependent populations, impacting relapse related factors such as stress dysregulation and impulse control. PMID:21314758

  6. Evaluating Solid Boost Demonstrator Motor Specific Impulse Performance

    Science.gov (United States)

    Ahmad, Rashid A.; Laubacher, Brian

    2001-02-01

    The Integrated High Payoff Rocket Propulsion Technology (IHPRPT) Phase I solid Boost Demonstrator (Boost Demo) motor was fabricated as the Phase I demonstration of technologies from the IHPRPT program. This motor incorporates new technologies in an attempt to increase delivered performance compared with the IHPRPT Baseline motor. The IHPRPT Baseline motor and Boost Demo nozzle motor aft and nozzle contours are compared.

  7. 20mN, Variable Specific Impulse Colloid Thruster Project

    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...

  8. Experimental study of plasma focusing in erosion plasma accelerators. V. Mechanism of plasma focusing in a magnetoplasma compressor

    International Nuclear Information System (INIS)

    Experimental results are reported from a study of the dynamics, microscopic structure, and stability of successive developmental stages of high-current plasmodynamic discharges in magnetoplasma compressors of the erosion type under conditions of intense radiation transport. Particular attention was given to the transient stage of plasma focusing behind the cutoff of the accelerating channel, and to secondary pinching processes in the second half-period of the discharge current and methods for analyzing them when limited diagnostic facilities are available. It is shown that thermal instabilities, which dominate during the stages of formation and quasisteady flow in the compressed zone, do not cause the nonideal discharge plasma to have anomalous thermodynamic and transport properties; the accelerated plasma, which is thermalized in the compressed zone, is macroscopically stable when the current shell interacts with the relatively cold vapor (this interaction is accompanied by development of an intense shock-wave structure and power instabilities in various modes). It is demonstrated that either an inertial + Hall mechanism of plasma focusing or two-stage inertial compression of the plasma is possible, regardless of the chemical composition and ionization state of the electric discharge plasma. In the two-stage method of plasma compression, the plasma is compressed toward the central anode in the accelerating channel by the Hall effect and as a result of additional pinc effect and as a result of additional pinching in the outgoing Z currents; when energy is input to the MHD compression zone in a self-consistent manner, this makes it possible to control the dimensions and the dynamic and energy characteristics of the plasma stream

  9. Entrainment and the cranial rhythmic impulse.

    Science.gov (United States)

    McPartland, J M; Mein, E A

    1997-01-01

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

  10. Micropower impulse radar technology and applications

    Energy Technology Data Exchange (ETDEWEB)

    Mast, J., LLNL

    1998-04-15

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

  11. 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

  12. 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.

  13. Stall Control Simulation with an Impulse Jet

    Science.gov (United States)

    Jee, Sol Keun; Moser, Robert; Lopez, Omar

    2010-11-01

    An impulse jet is investigated numerically to understand the mechanism by which this jet controls a stalled flow over an airfoil. The DDES (delayed detached eddy simulation) turbulence model is used in this stall control study for a NACA 4415 airfoil at an angle of attack of 20 degree and Reynolds number Re=570,000. An impulse jet, which is applied upstream of the nominal flow separation point, generates vortices that convect downstream, interact with the separating shear layer, dismantle the layer and allow following vortices to propagate along the surface in the separation region. These following vortices shift the separation point aft reattaching the boundary layer, which returns slowly to its initial stall condition, as observed in wind-tunnel experiments. A simple model of the impulse jet actuator used herein is found to be sufficient to represent the global effects of the jet on the stalled flow because it correctly represents the momentum injected into the flow.

  14. Cortical thickness of superior frontal cortex predicts impulsiveness and perceptual reasoning in adolescence.

    Science.gov (United States)

    Schilling, C; Kühn, S; Paus, T; Romanowski, A; Banaschewski, T; Barbot, A; Barker, G J; Brühl, R; Büchel, C; Conrod, P J; Dalley, J W; Flor, H; Ittermann, B; Ivanov, N; Mann, K; Martinot, J-L; Nees, F; Rietschel, M; Robbins, T W; Smolka, M N; Ströhle, A; Kathmann, N; Garavan, H; Heinz, A; Schumann, G; Gallinat, J

    2013-05-01

    Impulsiveness is a pivotal personality trait representing a core domain in all major personality inventories. Recently, impulsiveness has been identified as an important modulator of cognitive processing, particularly in tasks that require the processing of large amounts of information. Although brain imaging studies have implicated the prefrontal cortex to be a common underlying representation of impulsiveness and related cognitive functioning, to date a fine-grain and detailed morphometric analysis has not been carried out. On the basis of ahigh-resolution magnetic resonance scans acquired in 1620 healthy adolescents (IMAGEN), the individual cortical thickness (CT) was estimated. Correlations between Cloninger's impulsiveness and CT were studied in an entire cortex analysis. The cluster identified was tested for associations with performance in perceptual reasoning tasks of the Wechsler Intelligence Scale for Children (WISC IV). We observed a significant inverse correlation between trait impulsiveness and CT of the left superior frontal cortex (SFC; Monte Carlo Simulation P<0.01). CT within this cluster correlated with perceptual reasoning scores (Bonferroni corrected) of the WISC IV. On the basis of a large sample of adolescents, we identified an extended area in the SFC as a correlate of impulsiveness, which appears to be in line with the trait character of this prominent personality facet. The association of SFC thickness with perceptual reasoning argues for a common neurobiological basis of personality and specific cognitive domains comprising attention, spatial reasoning and response selection. The results may facilitate the understanding of the role of impulsiveness in several psychiatric disorders associated with prefrontal dysfunctions and cognitive deficits. PMID:22665261

  15. 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.

  16. 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

  17. 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…

  18. 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…

  19. Increased reflection impulsivity in patients with ephedrone induced Parkinsonism

    Science.gov (United States)

    Djamshidian, Atbin; Sanotsky, Yanosh; Matviyenko, Yuriy; O’Sullivan, Sean S.; Sharman, Stephen; Selikhova, Marianna; Fedoryshyn, Ludmyla; Filts, Yuriy; Bearn, Jenny; Lees, Andrew J.; Averbeck, Bruno B.

    2012-01-01

    Aims To examine a syndrome of chronic manganism that occurs in drug addicts in Eastern Europe who use intravenous methcathinone (ephedrone) contaminated with potassium permanganate. The basal ganglia, especially the globus pallidus and the putamen, are damaged irreversibly in many cases. Routine neuropsychological assessment has revealed no cognitive deficits despite widespread abnormalities on brain imaging studies and severe extrapyramidal motor handicap on clinical examination. Design Case control study. Setting Ephedrone patients and patients with opioid dependence were recruited from Lviv, Ukraine. Participants We tested 15 patients with ephedrone induced toxicity, 13 opiate dependent patients, who were receiving opioid replacement therapy and 18 matched healthy volunteers. Measurements The ‘beads task’, an information gathering task to assess reflection impulsivity was used and feedback learning, working memory and risk taking were also assessed. Findings Opiate dependent patients differed from controls on three out of four tasks, whereas ephedrone patients differed from controls on only one task. More specifically both patient groups were more impulsive and made more irrational choices on the beads task than controls (p0.1) or risk taking (p>0.1) compared with controls. Opioid dependent patients had significantly worse working memory (p<0.001) and were significantly more risk prone than controls (p=0.002). Conclusions Ephedrone patients may have similar deficits in information gathering and decision making to opiate dependent patients, with preservation of working memory and risk taking. This may reflect specific damage to anterior cingulate- basal ganglia loops. PMID:23228208

  20. 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.

  1. Quantal-classical correspondence impulse theory

    Science.gov (United States)

    Flannery; Vrinceanu

    2000-07-01

    The quantal impulse cross section is derived in a novel form appropriate for direct classical correspondence. The classical impulse cross section is then uniquely defined and yields the first general classical expression for nl-n(')l(') collisional transitions. The derived cross sections satisfy the optical theorem and detailed balance. Direct connection with the classical binary encounter approximation is also firmly established. The unified method introduced is general in its application to various collision and recombination processes and enables new directions of enquiry to be pursued quite succinctly. PMID:10991144

  2. Intensity impulse response of SDM links.

    Science.gov (United States)

    Mecozzi, Antonio; Antonelli, Cristian; Shtaif, Mark

    2015-03-01

    We study the response of space-division multiplexed fiber links to an excitation by a short impulse of the optical intensity. We show that, in the presence of full mixing, the intensity impulse response is Gaussian, confirming recently reported experimental observations, and relate its variance to the mean square of the mode dispersion vector of the link ??. The good agreement between our theory and the previously published experiments provides solid foundations to the random coupling model of SDM fiber links, and provides a tool for efficient design of MIMO-DSP receivers. PMID:25836803

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

    International Nuclear Information System (INIS)

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

  4. Distinct Circuits Underlie the Effects of 5-HT1B Receptors on Aggression and Impulsivity.

    Science.gov (United States)

    Nautiyal, Katherine M; Tanaka, Kenji F; Barr, Mary M; Tritschler, Laurent; Le Dantec, Yannick; David, Denis J; Gardier, Alain M; Blanco, Carlos; Hen, René; Ahmari, Susanne E

    2015-05-01

    Impulsive and aggressive behaviors are both modulated by serotonergic signaling, specifically through the serotonin 1B receptor (5-HT1BR). 5-HT1BR knockout mice show increased aggression and impulsivity, and 5-HT1BR polymorphisms are associated with aggression and drug addiction in humans. To dissect the mechanisms by which the 5-HT1BR affects these phenotypes, we developed a mouse model to spatially and temporally regulate 5-HT1BR expression. Our results demonstrate that forebrain 5-HT1B heteroreceptors expressed during an early postnatal period contribute to the development of the neural systems underlying adult aggression. However, distinct heteroreceptors acting during adulthood are involved in mediating impulsivity. Correlating with the impulsivity, dopamine in the nucleus accumbens is elevated in the absence of 5-HT1BRs and normalized following adult rescue of the receptor. Overall, these data show that while adolescent expression of 5-HT1BRs influences aggressive behavior, a distinct set of 5-HT1B receptors modulates impulsive behavior during adulthood. PMID:25892302

  5. 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.

  6. Impulsivity, self-regulation,and pathological video gaming among youth: testing a mediation model.

    Science.gov (United States)

    Liau, Albert K; Neo, Eng Chuan; Gentile, Douglas A; Choo, Hyekyung; Sim, Timothy; Li, Dongdong; Khoo, Angeline

    2015-03-01

    Given the potential negative mental health consequences of pathological video gaming, understanding its etiology may lead to useful treatment developments. The purpose of the study was to examine the influence of impulsive and regulatory processes on pathological video gaming. Study 1 involved 2154 students from 6 primary and 4 secondary schools in Singapore. Study 2 involved 191 students from 2 secondary schools. The results of study 1 and study 2 supported the hypothesis that self-regulation is a mediator between impulsivity and pathological video gaming. Specifically, higher levels of impulsivity was related to lower levels of self-regulation, which in turn was related to higher levels of pathological video gaming. The use of impulsivity and self-regulation in predicting pathological video gaming supports the dual-system model of incorporating both impulsive and reflective systems in the prediction of self-control outcomes. The study highlights the development of self-regulatory resources as a possible avenue for future prevention and treatment research. PMID:22199156

  7. 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.

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

    Science.gov (United States)

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

    2014-06-30

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

  9. Final report of LDRD project: Electromagnetic impulse radar for detection of underground structures

    Energy Technology Data Exchange (ETDEWEB)

    Loubriel, G.; Aurand, J.; Buttram, M.; Zutavern, F.; Brown, D.; Helgeson, W.

    1998-03-01

    This report provides a summary of the LDRD project titled: Electromagnetic impulse radar for the detection of underground structures. The project met all its milestones even with a tight two year schedule and total funding of $400 k. The goal of the LDRD was to develop and demonstrate a ground penetrating radar (GPR) that is based on high peak power, high repetition rate, and low center frequency impulses. The idea of this LDRD is that a high peak power, high average power radar based on the transmission of short impulses can be utilized effect can be utilized for ground penetrating radar. This direct time-domain system the authors are building seeks to increase penetration depth over conventional systems by using: (1) high peak power, high repetition rate operation that gives high average power, (2) low center frequencies that better penetrate the ground, and (3) short duration impulses that allow for the use of downward looking, low flying platforms that increase the power on target relative to a high flying platform. Specifically, chirped pulses that are a microsecond in duration require (because it is difficult to receive during transmit) platforms above 150 m (and typically 1 km) while this system, theoretically could be at 10 m above the ground. The power on target decays with distance squared so the ability to use low flying platforms is crucial to high penetration. Clutter is minimized by time gating the surface clutter return. Short impulses also allow gating (out) the coupling of the transmit and receive antennas.

  10. 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.

  11. Behavioral and Biological Indicators of Impulsivity in the Development of Alcohol Use, Problems, and Disorders

    Science.gov (United States)

    Lejuez, C.W.; Magidson, Jessica F.; Mitchell, Suzanne H.; Sinha, Rajita; Stevens, Michael C.; de Wit, Harriet

    2011-01-01

    Alcohol Use Disorders (AUDs) are a devastating public health problem. The construct of impulsivity is biologically-based and heritable, and its various dimensions are relevant for understanding alcohol use. The goal of the current manuscript is to review recent behavioral and biological research examining various dimensions of impulsivity, and their relation to AUDs from risk for initial use through dependence and relapse. Moreover, we also highlight key psychological variables including affective processes as they relate to current use and early indications of alcohol problems, as well as psychopathology, violence, and aggression in relation to AUDs. Each section includes a critical summary and we conclude the review with future directions focused on issues relevant to measurement, causality, and intervention. Throughout the review, we attempt to be as specific as possible about the dimensions of impulsivity being referenced, while attempting to draw parallels and highlighting differences as the existing literature allows. PMID:20491733

  12. 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.

  13. Origin of multiply-impulsive emission from solar flares

    International Nuclear Information System (INIS)

    Over the past twenty years, our understanding of solar flares has been augmented greatly by the advent of rocket-, balloon-, and satellite-borne instrumentation dedicated to observations of the sun. In particular, the use of spacecraft-borne detectors has permitted coverage of the shorter-wavelength regions of the electromagnetic spectrum, inaccessible to ground-based facilities. Hard x-ray emission from solar flares provides direct evidence of the role of energetic electrons in these powerful explosions. Analyses of flare-associated hard x-rays, in conjunction with coincident coverage at other wavelengths, have contributed much of our current understanding of the basic energizing processes and resultant particle acceleration which characterize the flare phenomenon. During the previous solar maximum, the hard x-ray burst spectrometer on board the OSO-5 satellite observed hundreds of hard x-ray events on the sun, in the energy range 14 to 254 keV. The analysis and interpretation of a set of complex x-ray bursts, selected from the OSO-5 data, are presented in this work. The multiply-impulsive events were chosen on the basis of morphological characteristics: each event appears to consist of a number of overlapping spikes, with no apparent gradual component of significance. The two-stage events were selected on the basis of both morphological characteristics and association with the appropriate phenomena at other wavelengths. The present research is focussed on two specifpresent research is focussed on two specific aspects of the multiple-spike and two-stage bursts: (1) to look for the causes of multiplicity in complex impulsive events; and (2) to compare the impulsive emissions with associated gradual emissions, to pinpoint the basic processes which are applicable to each phase alone

  14. 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...

  15. 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...

  16. 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...

  17. 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

  18. Arbitration between controlled and impulsive choices

    Science.gov (United States)

    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 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

  19. 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,…

  20. Impulse Control of Multidimensional Jump Diffusions

    CERN Document Server

    Davis, Mark H A; Wu, Guoliang

    2009-01-01

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

  1. 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.

  2. Impulse Formulations of Hall Magnetohydrodynamic Equations

    OpenAIRE

    Shivamoggi, Bhimsen K.

    2008-01-01

    Impulse formulations of Hall magnetohydrodynamic (MHD) equations are developed. The Lagrange invariance of a generalized ion magnetic helicity is established for Hall MHD. The physical implications of this Lagrange invariant are discussed. The discussion is then extended to compressible Hall MHD. Compressibility effects are shown not to affect, as to be expected, the physical implications of the generalized ion magnetic helicity Lagrange invariant.

  3. 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.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Tiihonen, J.; Hallikainen, T.; Hakola, P. [Department of Forensic Psychiatry, University of Kuopio and Niuvanniemi Hospital, FIN-70240 Kuopio (Finland); Kuikka, J.T.; Bergstroem, K.A.; Yang, J. [Department of Clinical Physiology, Kuopio University Hospital, FIN-70210 Kuopio (Finland); Karhu, J. [Department of Clinical Neurophysiology, Kuopio University Hospital, FIN-70210 Kuopio (Finland); Viinamaeki, H.; Lehtonen, J. [Department of Psychiatry, Kuopio University Hospital, FIN-70210 Kuopio (Finland)

    1997-10-01

    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{beta}-carbomethoxy-3{beta}(4-iodophenyl)tropane ([{sup 123}I]{beta}-CIT) as the tracer. The blind quantitative analysis revealed that the 5-HT specific binding of [{sup 123}I]{beta}-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.) With 4 figs., 2 tabs., 55 refs.

  5. 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.

  6. 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...

  7. 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.

  8. Oscillation for higher order nonlinear ordinary differential equations with impulses

    Directory of Open Access Journals (Sweden)

    Chaolong Zhang

    2006-02-01

    Full Text Available In this paper, we study the oscillation of solutions to higher order nonlinear ordinary differential equations with impulses. Several criteria for the oscillations of solutions are given. We find some suitable impulse functions such that all solutions are oscillatory under the impulse control.

  9. Adaptive-impulsive synchronization of uncertain complex dynamical networks

    International Nuclear Information System (INIS)

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

  10. 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.

  11. 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...

  12. Mechanical impulses can control metaphase progression in a mammalian cell.

    Science.gov (United States)

    Itabashi, Takeshi; Terada, Yasuhiko; Kuwana, Kenta; Kan, Tetsuo; Shimoyama, Isao; Ishiwata, Shin'ichi

    2012-05-01

    Chromosome segregation machinery is controlled by mechanochemical regulation. Tension in a mitotic spindle, which is balanced by molecular motors and polymerization-depolymerization dynamics of microtubules, is thought to be essential for determining the timing of chromosome segregation after the establishment of the kinetochore-microtubule attachments. It is not known, however, whether and how applied mechanical forces modulate the tension balance and chemically affect the molecular processes involved in chromosome segregation. Here we found that a mechanical impulse externally applied to mitotic HeLa cells alters the balance of forces within the mitotic spindle. We identified two distinct mitotic responses to the applied mechanical force that either facilitate or delay anaphase onset, depending on the direction of force and the extent of cell compression. An external mechanical impulse that physically increases tension within the mitotic spindle accelerates anaphase onset, and this is attributed to the facilitation of physical cleavage of sister chromatid cohesion. On the other hand, a decrease in tension activates the spindle assembly checkpoint, which impedes the degradation of mitotic proteins and delays the timing of chromosome segregation. Thus, the external mechanical force acts as a crucial regulator for metaphase progression, modulating the internal force balance and thereby triggering specific mechanochemical cellular reactions. PMID:22523237

  13. Impulse Response from Seismic Interferometry and Earthquake Simulations

    Science.gov (United States)

    Juarez, A.; Ramirez-Guzman, L.

    2014-12-01

    We study the Green´s function (GF) retrieval based on the cross-correlation of numerically generated signals and its application to tomographic studies in central Mexico. The GF between two receivers is typically obtained based on the cross-correlation of noise recorded in two stations. Nevertheless, in this research we use large-scale earthquake numerical simulations to construct appropriate signals and optimal linear combinations of the displacements at two stations due to a small number of double-couple sources in a layered media to retrieve the Green´s function between receivers. The impulse response is obtained successfully by applying the cross-correlation, following standard interferometry theory. Additionally, the azimuthal dependence on the cross-correlations as an estimate of the impulse response is discussed using specific source locations. The main objective of our research is to elucidate the applicability of seismic interferometry in order to extend the frequency range and quality of tomographic studies based on observed regional earthquake records and dispersion maps. Thus, we show the results of the GF obtained using the aforementioned procedure in a realistic three-dimensional model of central Mexico, and quantify the discrepancies against the exact numerically computed GF. We conclude that a fair recovery is achieved by inverting velocity profiles at selected stations.

  14. Clarifying the relationship between impulsive delay discounting and nicotine dependence.

    Science.gov (United States)

    Amlung, Michael; MacKillop, James

    2014-09-01

    Impulsive delayed reward discounting (DRD) has been linked to nicotine dependence, but with some inconsistency. This may be related to the considerable variability in the literature with regard to the DRD assessments used, particularly in the case of the reward magnitudes assessed. In addition, previous studies have often not considered concurrent substance use when examining the relationship between DRD and nicotine dependence. The current study sought to further clarify the relationship between DRD and nicotine dependence by characterizing DRD across diverse reward magnitudes and incorporating other substance use. Daily smokers (N = 933) were assessed for DRD preferences across nine reward magnitudes (delayed reward range: $2.50-$850), comorbid substance use, and relevant demographic variables (age, education, income). A significant large effect size magnitude effect was found for DRD, reflecting steeper discounting for smaller delayed rewards, but significant correlations across magnitudes also suggested similar relative levels of discounting. Principal components analysis (PCA) was used to generate a single latent index of discounting across all magnitudes that accounted for 69% of the total variance. In correlation and regression analyses, steeper composite DRD was significantly associated with nicotine dependence severity. This relationship remained statistically significant after incorporating demographic variables and alcohol and illicit drug use. These findings provide evidence of a specific link between impulsive DRD and nicotine dependence and reveal that this association is robust across a broad range of monetary rewards. The study also demonstrates the utility of using PCA to generate latent indices of delay discounting across multiple magnitudes of delayed reward. PMID:24841186

  15. 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.

  16. 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

  17. [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

  18. PARTS: (Plasma Accelerated Reusable Transport System)

    Science.gov (United States)

    Aherne, Michael; Davis, Phil; England, Matt; Gustavsson, Jake; Pankow, Steve; Sampaio, Chere; Savella, Phil

    2002-01-01

    The Plasma Accelerated Reusable Transport System (PARTS) is an unmanned cargo shuttle intended to ferry large payloads to and from Martian orbit using a highly efficient VAriable Specific Impulse Magnetoplasma Rocket (VASIMR). The design of PARTS focuses on balancing cost and minimizing transit time for a chosen payload consisting of vehicles, satellites, and other components provided by interested parties.

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

    International Nuclear Information System (INIS)

    The aim of this study was to evaluate acoustic radiation force impulse imaging for cervical lymphadenopathy in routine clinical practice and to correlate the acoustic radiation force impulse values with the morphological signs and the pathological results, which were used as the reference standard. The virtual touch tissue quantification values were analyzed in 123 patients (mean age 40.8 years, range 1–81 years) with 181 cervical lymph nodes (87 benign, 94 malignant). The diagnostic performance of acoustic radiation force impulse values were evaluated with respect to sensitivity, specificity, and area under the curve using a receiver operating characteristic curve analysis. The mean virtual touch tissue quantification values of the benign lesions (2.01 ± 0.95 m/s) differed from that of the malignant lesions (4.61 ± 2.56 m/s; P < 0.001). The cutoff level for virtual touch tissue quantification value for malignancy was estimated to be 2.595 m/s. Using the receiver operating characteristic curve curves with the cutoff value, the virtual touch tissue quantification value predicted malignancy with a sensitivity of 82.9%, specificity of 93.1% and gave an areas under the curve of 0.906 (95% CI 0.857–0.954). Acoustic radiation force impulse is feasible for cervical lymph nodes and provides quantitative elasticity measurements, which may complement B-mode ultrasound and potentially improve the characterization of cervical lymph nodes

  20. Fast changes in direction during human locomotion are executed by impulsive activation of motor modules.

    Science.gov (United States)

    Oliveira, A S; Silva, P B; Lund, M E; Kersting, U G; Farina, D

    2013-01-01

    This study investigated the modular control of complex locomotor tasks that require fast changes in direction, i.e., cutting manoeuvres. It was hypothesized that such tasks are accomplished by an impulsive (burst-like) activation of a few motor modules, as observed during walking and running. It was further hypothesized that the performance in cutting manoeuvres would be associated to the relative timing of the activation impulses. Twenty-two healthy men performed 90° side-step cutting manoeuvres while electromyography (EMG) activity from 16 muscles of the supporting limb and trunk, kinematics, and ground reaction forces were recorded. Motor modules and their respective temporal activations were extracted from the EMG signals by non-negative matrix factorization. The kinematic analysis provided the velocity of the centre of mass and the external work absorbed during the load acceptance (negative work, external work during absorption (W-Abs)) and propulsion phases (positive work, external work during propulsion (W-Prp)) of the cutting manoeuvres. Five motor modules explained the EMG activity of all muscles and were driven in an impulsive way, with timing related to the initial contact (M2), load acceptance (M3), and propulsion (M4). The variability in timing between impulses across subjects was greater for cutting manoeuvres than for running. The timing difference between M2 and M3 in the cutting manoeuvres was significantly associated to W-Abs (r(2)=0.45) whereas the timing between M3 and M4 was associated to W-Prp (r(2)=0.43). These results suggest that complex locomotor tasks can be achieved by impulsive activation of muscle groups, and that performance is associated to the specific timing of the activation impulses. PMID:23085217

  1. 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

  2. Viscoplastic behaviors of structure under impulsive loadings

    International Nuclear Information System (INIS)

    The dynamic responses of structure under impulsive loading have been investigated according to its duration, based on the theory of viscoplasticity which can appropriately represents the effects of plasticity and rheology simultaneously. The viscoplastic model has been implemented into the two-dimensional finite element system to solve plane stress, plane strain or axisymmetric problems, and the implicit integration scheme, of which solutions are unconditionally stable for relatively large time step length, has been developed to simulate viscoplastic straining after deriving the explicit relationship between stress and strain at a material point level. After simulation, one carefully concludes that duration as well as magnitude of impulsive loading plays an important role in design of structures in the nuclear power plants. As the duration increases, the viscoplastic straining occurs, and the components of higher natural frequencies are negligible, which leads that the response curve becomes smooth corresponding to the damping mechanism of viscoplastic straining. (author)

  3. A review of impulsive phase phenomena

    Science.gov (United States)

    Dejager, C.

    1986-01-01

    A brief review is given of impulsive phase phenomena in support of the models used to compute the energies of the different components of the flares under study. The observational characteristics of the impulsive phase are discussed as well as the evidence for multi-thermal or non-thermal phenomena. The significance of time delays between hard X-rays and microwaves is discussed in terms of electron beams and Alfven waves, two-step acceleration, and secondary bursts at large distances from the primary source. Observations indicating the occurrence of chromospheric evaporation, coronal explosions, and thermal conduction fronts are reviewed briefly, followed by the gamma ray and neutron results. Finally, a preferred flare scenario and energy source are presented involving the interactions in a complex of magnetic loops with the consequent reconnection and electron acceleration.

  4. Thin foil electron beam impulse experiments

    International Nuclear Information System (INIS)

    Measurements were made of the impulse produced by thin, metallic foils that had been rapidly and uniformly heated in depth, to melt or vaporization by an electron beam. Blowoff predictions were done using two hydrocodes: PUFF, with the GRAY three phase equation of state, and CHART, with its three phase equation of state. An acceptable correlation variable, folding in electron beam and material characteristics, was derived and used successfully to plot and analyze predicted and measured data trends. We conclude that PUFF and CHART, with their present equations of state, predict impulse correctly within tolerances of +-30 percent. Unfortunately, the lack of repeatability of the electron beam machine precludes its use for doing more accurate equation of state measurements. (9 figs, 5 tables, 10 refs.) (auth)

  5. Interdependencies of Neural Impulse Pattern and Synchronization

    Science.gov (United States)

    Braun, Hans; Postnova, Svetlana; Schneider, Horst

    2008-03-01

    Neuronal synchronization plays a crucial role in many physiological functions such as information binding and wake-sleep transitions as well as in pathophysiological processes like Parkinson's disease and epileptic seizures. The occurrence of synchronized activity is often associated with significant alterations of the neuronal impulse pattern, mostly with a transition from tonic firing to burst discharges. We have used Hodgkin-Huxley type simulations to study how alterations of individual neurons' dynamics influence the synchronization in electrotonic coupled networks. The individual neurons have been tuned from tonic firing to bursting with chaotic dynamics in between. Our results demonstrate that these transitions have significant impact on the neurons' synchronization. Vice versa, the synchronization state can essentially modify the impulse pattern. The most remarkably effects appear when the individual neurons operate in a periodically tonic firing regime close to the transition to chaos.

  6. A Class of Solvable Impulse Control Problems

    International Nuclear Information System (INIS)

    We consider a class of stochastic impulse control problems where the controlled process evolves according to a linear, regular, and time homogeneous diffusion. We state a set of easily verifiable sufficient conditions under which the problem is explicitly solvable. We also state an algebraic equation from which the optimal impulse boundary can be determined and, given this threshold, we present the value of the optimal policy interms of the minimal increasing r-excessive mapping for the controlled diffusion. We also consider the comparative static properties of the optimal policy and state a set of typically satisfied conditions under which increased volatility unambiguously increases the value of the optimal policy and expands the continuation region where exercising the irreversible policy is suboptimal. We also illustrate our results explicitly in two models based on geometric Brownian motion

  7. Pinning impulsive control algorithms for complex network

    Science.gov (United States)

    Sun, Wen; Lü, Jinhu; Chen, Shihua; Yu, Xinghuo

    2014-03-01

    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. 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

  9. Strength measurement of impulse compacted moulding sand

    Directory of Open Access Journals (Sweden)

    T. Mikulczy?ski

    2011-01-01

    Full Text Available Analysis of impulse compaction process shows that during compaction process moulding sand is subject to deformation and changes oftotal pressure, measured inside compacted moulding sand, represent fading sinusoid. Measured pressure values in stationary states (aftercompaction process are equal to the sum of squeezing pressure pc and the pressure resulting from compacting the sandmix pu, whichexpresses the obtained strength. Therefore experimental research of moulding sands were conducted. Strength factor Rc and pressure puvalues were determined as a function of densening degree ?. Analysis of presented results proves that pu pressure resulting fromcompacting of the moulding sand expresses compressive strength factor Rc. This confirms that developed methodology permits strengthmeasurements of moulding sand in the mould. Moreover as it is possible to determine pu values with simulation research of developedmathematical model of impulse process it is possible to determine compressive strength factor.

  10. Solar proton flares with weak impulsive phases

    International Nuclear Information System (INIS)

    The current picture of a proton flare includes a well-defined impulsive phase characterized by a prominent hard X-ray (or microwave) peak. Lin and Hudson have argued that the correlation between intense flare hard X-ray bursts and large proton events is evidenced that the second stage of particle acceleration, during which the protons observed at 1 AU are thought to be accelerated, is fueled by energy originally contained in flash phase 10--100 keV electrons. In our examination of large (J[>10 MeV]-2 s-1 sr-1), prompt, proton events occurring between 1965--1979, however, we found several events that originated in flares with relatively weak (Sp[9 GHz]<100 sfu) impulsive phases. Various lines of evidence indicate that these flares were associated with mass ejection events which, given the absence of a prominent flash phase, appear to have been magnetically driven

  11. Science of NHL Hockey: Force, Impulse & Collisions

    Science.gov (United States)

    NBC Learn

    2010-10-07

    NHL hockey pucks are made of vulcanized rubber and weigh between 5.5 and 6 ounces (160 - 170 g). During a game, every movement of the puck follows the laws of physics and illustrates the concepts of force, impulse and collisions. "Science of NHL Hockey" is a 10-part video series produced in partnership with the National Science Foundation and the National Hockey League.

  12. Modeling High Power Impulse Magnetron Sputtering Discharges

    OpenAIRE

    Huo, Chunqing

    2012-01-01

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

  13. Impulsive flow over an elliptic cylinder

    Science.gov (United States)

    Jafroudi, Hamid; Yang, H. T.

    The initial flow field of an impulsively started incompressible, viscous flow over an elliptic cylinder is analyzed by the method of matched asymptotic expansions. The second-order solution of Wang (1972), as recovered by Billings (1984), and Hermel (1984) showed singularities in the progression of flow separation points on the perimeter of the ellipse. This singular behavior is studied in some detail. The separation time, surface vorticity, pressure distribution, lift, drag and streamline pattern are presented.

  14. 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...

  15. Fundamentals of High Power Impulse Magnetron Sputtering

    OpenAIRE

    Böhlmark, Johan

    2006-01-01

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

  16. Spalling of aluminum plates during impulsive heating

    Energy Technology Data Exchange (ETDEWEB)

    Akhmadeev, N.Kh.; Sorokina, E.P.; Iaushev, K.K.

    1983-09-01

    The impulsive heating of flat aluminum plates by electromagnetic radiation is investigated numerically. The irradiation of a plate results in the generation of compressive stresses up to several GPa for absorption energies of about 10 kJ. The generation of compressive stresses is due to an instantaneous heating of the plate. During the unloading stage, after irradiation is discontinued, considerable tensile stresses are generated. These are capable of producing spall damage on both the irradiated and the shadow surface. 5 references.

  17. Reducing confidence bands for simulated impulse responses

    OpenAIRE

    Lütkepohl, Helmut

    2012-01-01

    It is emphasized that the shocks in structural vector autoregressions are only identified up to sign and it is pointed out that this feature can result in very misleading confidence intervals for impulse responses if simulation methods such as Bayesian or bootstrap methods are used. The confidence intervals heavily depend on which variable is used for fixing the sign of the initial responses. In particular, when the shocks are identified via long-run restrictions the problem can be severe. It...

  18. Robust Algorithm for Impulse Noise Detection

    OpenAIRE

    Manohar Annappa Koli

    2012-01-01

    Efficiency of noise removing algorithms depends on two main parameters first one is how accurately it identify the noisy pixels and second one is how much accurately it calculate the replacing value for noisy pixels. This Paper presents highly efficient algorithm to detect impulse noise (salt and pepper) up to 99% of noise ratio. Experimental results shows efficiency of algorithm is more than 99.5 %.

  19. FEM Analysis of Turgo Impulse Turbine Blade

    OpenAIRE

    Khurana, Sourabh; Goel, Varun; Kumar, Anoop

    2013-01-01

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

  20. 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.)

  1. Leupeptin reduces impulse noise induced hearing loss

    Directory of Open Access Journals (Sweden)

    Gavriel Haim

    2011-12-01

    Full Text Available Abstract Background Exposure to continuous and impulse noise can induce a hearing loss. Leupeptin is an inhibitor of the calpains, a family of calcium-activated proteases which promote cell death. The objective of this study is to assess whether Leupeptin could reduce the hearing loss resulting from rifle impulse noise. Methods A polyethelene tube was implanted into middle ear cavities of eight fat sand rats (16 ears. Following determination of auditory nerve brainstem evoked response (ABR threshold in each ear, the animals were exposed to the noise of 10 M16 rifle shots. Immediately after the exposure, saline was then applied to one (control ear and non-toxic concentrations of leupeptin determined in the first phase of the study were applied to the other ear, for four consecutive days. Results Eight days after the exposure, the threshold shift (ABR in the control ears was significantly greater (44 dB than in the leupeptin ears (27 dB. Conclusion Leupeptin applied to the middle ear cavity can reduce the hearing loss resulting from exposure to impulse noise.

  2. 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

  3. Impulsive Injection for Compressor Stator Separation Control

    Science.gov (United States)

    Culley, Dennis E.; Braunscheidel, Edward P.; Bright, Michelle M.

    2005-01-01

    Flow control using impulsive injection from the suction surface of a stator vane has been applied in a low speed axial compressor. Impulsive injection is shown to significantly reduce separation relative to steady injection for vanes that were induced to separate by an increase in vane stagger angle of 4 degrees. Injected flow was applied to the airfoil suction surface using spanwise slots pitched in the streamwise direction. Injection was limited to the near-hub region, from 10 to 36 percent of span, to affect the dominant loss due to hub leakage flow. Actuation was provided externally using high-speed solenoid valves closely coupled to the vane tip. Variations in injected mass, frequency, and duty cycle are explored. The local corrected total pressure loss across the vane at the lower span region was reduced by over 20 percent. Additionally, low momentum fluid migrating from the hub region toward the tip was effectively suppressed resulting in an overall benefit which reduced corrected area averaged loss through the passage by 4 percent. The injection mass fraction used for impulsive actuation was typically less than 0.1 percent of the compressor through flow.

  4. Anomalous electron transport in high power impulse magnetron sputtering

    International Nuclear Information System (INIS)

    Oscillating electric fields in the megahertz range have been studied in a high power impulse magnetron sputtering (HIPIMS) plasma with the use of electric field probe arrays. One possible reason for these oscillations to occur is charge perturbation-or so-called modified two-stream instabilities (MTSIs). It is known that MTSIs give rise to acceleration of the charged plasma species and can give a net transport of electrons across the magnetic field lines. Measurements of these oscillations confirm trends, specifically of the frequency dependence on ion mass and magnetic field strength as expected from the theory of MTSI waves. These results help to explain the previously reported anomalous fast electron transport in HIPIMS discharges, where classical theory of diffusion using collisions to transport electrons has failed.

  5. The integrated design of powder aligning and impulse magnetizing systems

    International Nuclear Information System (INIS)

    This paper describes an integrated finite element based methodology for the design and analysis of powder aligning systems and impulse magnetizing fixtures for the manufacture of anisotropic bonded Nd Fe B permanent magnet components. The relationships between the final component properties and the magnitudes of the aligning field and subsequent magnetizing field are illustrated by extensive experimental characterization of a commercial grade of anisotropic Nd Fe B injection moulding compound (Compodic NDA502E). The modelling techniques employed are experimentally validated by a case study on a 4 pole self-shielding rotor, the mould and fixture parameters for which were specifically selected to produce only partial alignment and saturation. The utility of an automated design technique is illustrated by the optimization of a mould to achieve near full alignment and saturation of the 4 pole rotor. (author)

  6. Synthesis of Room Impulse Responses for Variable Source Characteristics

    Directory of Open Access Journals (Sweden)

    M. Kunkemoeller

    2011-01-01

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

  7. Impulse control disorders in Parkinson's disease: clinical characteristics and implications.

    Science.gov (United States)

    Leeman, Robert F; Potenza, Marc N

    2011-04-01

    Impulse control disorders (ICDs), specifically those related to excessive gambling, eating, sex and shopping, have been observed in a subset of people with Parkinson's disease (PD). Although some initial case reports claimed that dopamine replacement therapies, particularly dopamine agonists, cause ICDs, more recent, larger and better controlled studies indicate a more complicated picture. While dopamine replacement therapy use is related to ICDs, other vulnerabilities, some related to PD and/or its treatment directly and others seemingly unrelated to PD, have also been associated with ICDs in PD. This suggests a complex etiology with multiple contributing factors. As ICDs occur in a sizable minority of PD patients and can be associated with significant distress and impairment, further investigation is needed to identify factors that can predict who may be more likely to develop ICDs. Clinical implications are discussed and topics for future research are offered. PMID:21709778

  8. Impulsive moving mirror model in a Schroedinger picture 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 studing 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 is the stability of the vacuum of Casimir. The dependence of vacuum state energy on the distance between the uniformly relatively moving mirrors is used to calculate from the impulsive moving model the Schroedinger equation in a Banach space. 21 refs

  9. 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

  10. The Relationship between Impulsive and Reflective Problem Solving Behavior

    Directory of Open Access Journals (Sweden)

    Vahid Nejati

    2012-03-01

    Full Text Available Background: Problem solving is an axial ability of educational promotion. Impulsive individual against reflectivity has fewer tendencies to involve in solving different problems. The purpose of present study was to evaluate the correlation between impulsivity, need for cognition and problem solving performance.Materials and Method: In this study, 72 individuals were randomly selected. Missionaries and cannibal's problem, Barrat Impulsivity Scale (BIS-11 and need for cognition scale were used for evaluation. Results: Findings show negative correlation between problem solving performance and impulsivity and positive correlation between problem solving and need for cognition. Duration of problem solving was not correlated with need for cognition and impulsivity.Conclusion: Pearson coefficient of correlation show that individuals with high level of need for cognition had better performance in problem solving accuracy but duration of problem solving is not related to impulsivity and need for cognition

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

    International Nuclear Information System (INIS)

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

  12. Alcoholics Anonymous and reduced impulsivity: a novel mechanism of change.

    Science.gov (United States)

    Blonigen, Daniel M; Timko, Christine; Moos, Rudolf H

    2013-01-01

    ABSTRACT   Reduced impulsivity is a novel, yet plausible, mechanism of change associated with the salutary effects of Alcoholics Anonymous (AA). Here, the authors review their work on links between AA attendance and reduced impulsivity using a 16-year prospective study of men and women with alcohol use disorders (AUDs) who were initially untreated for their drinking problems. Across the study period, there were significant mean-level decreases in impulsivity, and longer AA duration was associated with reductions in impulsivity. In turn, decreases in impulsivity from baseline to Year 1 were associated with fewer legal problems and better drinking and psychosocial outcomes at Year 1, and better psychosocial functioning at Year 8. Decreases in impulsivity mediated associations between longer AA duration and improvements on several Year 1 outcomes, with the indirect effects conditional on participants' age. Findings are discussed in terms of their potential implications for research on AA and, more broadly, interventions for individuals with AUDs. PMID:23327499

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

    OpenAIRE

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

    2004-01-01

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

  14. 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...

  15. 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...

  16. Impulsivity in Animal Models for Drug Abuse Disorders

    OpenAIRE

    Jentsch, J. David

    2008-01-01

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

  17. Impulsive generalized function synchronization of complex dynamical networks

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qunjiao, E-mail: qunjiao99@163.com [College of Mathematics and Computer Science, Wuhan Textile University, Wuhan 430073 (China); Chen, Juan [College of Science, Wuhan University of Science and Technology, Wuhan 430081 (China); Wan, Li [College of Mathematics and Computer Science, Wuhan Textile University, Wuhan 430073 (China)

    2013-11-22

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

  18. Impulsive generalized function synchronization of complex dynamical networks

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Huovinen, Pasi; Rouvinen, Petri

    2008-01-01

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

  20. Impulsivity and Parkinson’s disease: More than just disinhibition?

    OpenAIRE

    Antonelli, Francesca; Ray, Nicola; Strafella, Antonio P

    2011-01-01

    In the last few years it has become clear that impulsivity is a complex behaviour composed of different domains and dependent on different neural networks. The proposed pathogenetic mechanisms for the emergence of impulsivity disorders in Parkinson’s Disease (PD) can be broadly separated into three potentially interacting processes: the contribution of premorbid susceptibility to impulsivity, the contribution of the disease itself to the behaviour and the potential contribution of therapeut...

  1. Stochastic Impulse Control of Non-Markovian Processes

    CERN Document Server

    Djehiche, Boualem; Hdhiri, Ibtissam

    2008-01-01

    We consider a class of stochastic impulse control problems of general stochastic processes i.e. not necessarily Markovian. Under fairly general conditions we establish existence of an optimal impulse control. We also prove existence of combined optimal stochastic and impulse control of a fairly general class of diffusions with random coefficients. Unlike, in the Markovian framework, we cannot apply quasi-variational inequalities techniques. We rather derive the main results using techniques involving reflected BSDEs and the Snell envelope.

  2. Stabilizability of discrete chaotic systems via unified impulsive control

    Science.gov (United States)

    Xu, Honglei; Teo, Kok Lay

    2009-12-01

    This Letter is concerned with the asymptotical stabilization problem of discrete chaotic systems by using a novel unified impulsive control scheme. Sufficient conditions for asymptotical stability of the impulsive controlled discrete systems are obtained by means of the Lyapunov stability theory and algebraic inequality techniques. Finally, numerical simulations on the Hénon and Ushio discrete chaotic systems are presented to illustrate the effectiveness and usefulness of the unified impulsive control scheme.

  3. Stochastic Impulse Control of Non-Markovian Processes

    International Nuclear Information System (INIS)

    We consider a class of stochastic impulse control problems of general stochastic processes i.e. not necessarily Markovian. Under fairly general conditions we establish existence of an optimal impulse control. We also prove existence of combined optimal stochastic and impulse control of a fairly general class of diffusions with random coefficients. Unlike, in the Markovian framework, we cannot apply quasi-variational inequalities techniques. We rather derive the main results using techniques involving reflected BSDEs and the Snell envelope.

  4. 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...

  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. Alcoholics Anonymous and Reduced Impulsivity: A Novel Mechanism of Change

    OpenAIRE

    Blonigen, Daniel M.; Timko, Christine; Moos, Rudolf H.

    2013-01-01

    Reduced impulsivity is a novel, yet plausible, mechanism of change associated with the salutary effects of Alcoholics Anonymous (AA). Here, we review our work on links between AA attendance and reduced impulsivity using a 16-year prospective study of men and women with alcohol use disorders (AUD) who were initially untreated for their drinking problems. Across the study period, there were significant mean-level decreases in impulsivity, and longer AA duration was associated with reductions in...

  7. The definition of electro impulses used in weed control

    OpenAIRE

    Judaev I.V.

    2008-01-01

    In modern agriculture the use of chemicals and machines in weed control is not environmental and soil friendly. The use of electro impulses is offered to traditional ways of weed control. The researches done on technical characteristics of such operation and influence of these results on ecology gave picture that the use of electro impulses in weed control is harmless for environment and that is very effective. The basis for the technical project at designing of the electro impulse installati...

  8. A stochastic Ginzburg-Landau equation with impulsive effects

    Science.gov (United States)

    Nguyen Tien, Dung

    2013-05-01

    In this paper we consider a stochastic Ginzburg-Landau equation with impulsive effects. We first prove the existence and uniqueness of the global solution which can be explicitly represented via the solution of a stochastic equation without impulses. Then, based on our obtained result, we study the qualitative properties of the solution, including the boundedness of moments, almost surely exponential convergence and pathwise estimations. Finally, we give a first attempt to study a fractional version of impulsive stochastic Ginzburg-Landau equations.

  9. Adaptive Impulsive Outer Synchronization Between Drive-Response Dynamical Networks

    International Nuclear Information System (INIS)

    In this paper, outer synchronization between drive-response dynamical networks is investigated. Impulsive control combining with adaptive strategy is adopted to design controllers for achieving the goal. Based on the Lyapunov function method and mathematical analysis technique, a synchronization criterion with respect to the impulsive gains and intervals is analytically derived. From the criterion, the impulsive gains can adjust themselves to proper values when the impulsive intervals and some constants are fixed, and vice versa. Finally, two numerical examples are provided to verify the effectiveness of the derived result. (general)

  10. Analyses and Modeling Impulse Noise Generated by Household Appliances

    Directory of Open Access Journals (Sweden)

    Jaroslav Krejci

    2014-01-01

    Full Text Available This paper describes analysis of impulse noise generated by small household appliances. Furthermore we propose a new model of impulse noise based on the averaged power spectrum and the random phase generation with various phase distributions. The Gaussian, Weibull and Log-normal phase distributions were used to generate random phase. As a result of this approach, new impulses appear – they are different in the time domain but in the frequency domain new impulses have the desired power spectrum and the randomly generated phase.

  11. Dissecting impulsivity and its relationships to drug addictions.

    Science.gov (United States)

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

    2014-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Lavkesh Patidar *

    2015-01-01

    Full Text Available Impulse generator is an indispensible high voltage set. It simulates the voltage due to lightning and switching surges and used for testing of insulation of various electrical equipments like transformer, insulators etc. The standard impulse waveform could be used to test the strength of electrical equipments against the lightning. Lightning characteristics and standard impulse wave form are related to each other. But the lack of realization about relation between them would make the solution to produce better protection against lightning surge becomes harder. Lightning impulse voltage and standard impulse voltage (1.2/50?s are similar to each other. So, to achieving better protection of high voltage equipment study of impulse voltage waveform is very important. In this paper comparison has been made between standard impulse waveform obtained by simulating Marx impulse generation circuit in Pspice software and practical Marx circuit. This impulse waveform can be used to test the capacity of electrical equipment against the lightning and switching surge voltage.

  13. Impulsivity Modulates Performance Under Response Uncertainty in a Reaching Task

    Science.gov (United States)

    Tzagarakis, C; Pellizzer, G; Rogers, RD

    2013-01-01

    We sought to explore the interaction of the impulsivity trait with response uncertainty. To this end, we used a reaching task (Pellizzer and Hedges 2003) where a motor response direction was cued at different levels of uncertainty (1 cue, ie no uncertainty, 2 cues or 3 cues). Data from 95 healthy adults (54 F, 41 M) were analyzed. Impulsivity was measured using the Barratt Impulsiveness Scale version 11 (BIS-11). Psychophysical variables recorded were reaction time (RT), errors of commission (referred to as “early errors”) and errors of precision. Data analysis employed generalised linear mixed models and generalized additive mixed models. Results For the early errors there was an interaction of impulsivity with uncertainty and gender, with increased errors for high impulsivity in the one-cue condition for women and the three cue condition for men. There was no effect of impulsivity on precision errors or RT. However, the analysis of the effect of RT and impulsivity on precision errors showed a different pattern for high vs low impulsives in the high uncertainty (3-cue) condition. In addition, there was a significant early error speed-accuracy tradeoff for women, primarily in low uncertainty and a “reverse” speed accuracy tradeoff for men in high uncertainty. We believe that these results extend the results of past studies of impulsivity which help define it as a behavioural trait that modulates speed vs accuracy response styles depending on environmental constraints and highlight once more the importance of gender in the interplay of personality and behaviour. PMID:23239199

  14. Dopamine precursors depletion impairs impulse control in healthy volunteers.

    Science.gov (United States)

    Ramdani, Céline; Carbonnell, Laurence; Vidal, Franck; Béranger, Cyrille; Dagher, Alain; Hasbroucq, Thierry

    2015-01-01

    The aim of the present study was to decipher the role of the dopamine system in impulse control. Impulsive actions entail (i) activation of the motor system by an impulse, which is an urge to act and (ii) a failure to suppress that impulse, when inappropriate, in order to prevent an error. These two aspects of action impulsivity can be experimentally disentangled in conflict reaction time tasks such as the Simon task, which measures susceptibility to acting on spontaneous impulses (as well as the proficiency of suppressing these impulses). In 12 healthy volunteers performing a Simon task, dopamine availability was reduced with an amino acid drink deficient in the dopamine precursors, phenylalanine and tyrosine. Classic behavioral measures were augmented with an analysis of the electromyographic activity of the response effectors. Electromyography allows one to detect covert activations undetectable with strictly behavioral measures and further reveals the participants' ability to quickly suppress covert activations before they result in an overt movement. Following dopamine depletion, compared with a placebo condition, participants displayed comparable impulse activation but were less proficient at suppressing the interference from this activation. These results provide evidence that the dopamine system is directly involved in the suppression of maladaptive response impulses. PMID:25038871

  15. Modified impulsive synchronization of fractional order hyperchaotic systems

    International Nuclear Information System (INIS)

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

  16. 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.

  17. Inhibitory spillover:increase urination urgency facilitates impulse control in unrelated domains

    OpenAIRE

    Tuk, Mirjam A.; Trampe, Debra; Warlop, Luk

    2011-01-01

    Visceral states are known to reduce the ability to exert self-control. In the current research, we investigated how self-control is affected by a visceral factor associated with inhibition rather than with approach: bladder control. We designed four studies to test the hypothesis that inhibitory signals are not domain-specific but can spill over to unrelated domains, resulting in increased impulse control in the behavioral domain. In Study 1, participants’ urination urgency correlated with ...

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

    OpenAIRE

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

    2009-01-01

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

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

    Science.gov (United States)

    Whitmarsh, C. L., Jr.

    1972-01-01

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

  20. High power impulse magnetron sputtering discharge

    OpenAIRE

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

    2012-01-01

    The high power impulse magnetron sputtering (HiPIMS) discharge is a recent addition to plasma based sputtering technology. In HiPIMS, high power is applied to the magnetron target in unipolar pulses at low duty cycle and low repetition frequency while keeping the average power about 2 orders of magnitude lower than the peak power. This results in a high plasma density, and high ionization fraction of the sputtered vapor, which allows better control of the film growth by controlling the energy...

  1. 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

  2. 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.

  3. Gyratonic pp waves and their impulsive limit

    Science.gov (United States)

    Podolský, J.; Steinbauer, R.; Švarc, R.

    2014-08-01

    We investigate a class of gravitational pp waves which represent the exterior vacuum field of spinning particles moving with the speed of light. Such exact spacetimes are described by the original Brinkmann form of the pp-wave metric including the often-neglected off-diagonal terms. We put emphasis on a clear physical and geometrical interpretation of these off-diagonal metric components. We explicitly analyze several new properties of these spacetimes associated with the spinning character of the source, such as rotational dragging of frames, geodesic deviation, impulsive limits and the corresponding behavior of geodesics.

  4. [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

  5. Impulse source versus dodecahedral loudspeaker for measuring parameters derived from the impulse response in room acoustics.

    Science.gov (United States)

    San Martín, Ricardo; Arana, Miguel; Machín, Jorge; Arregui, Abel

    2013-07-01

    This study investigates the performance of dodecahedral and impulse sources when measuring acoustic parameters in enclosures according to ISO 3382-1 [Acoustics-Measurement of room acoustic parameters. Part 1: Performance spaces (International Organization for Standardization, Geneva, Switzerland, 2009)]. In general, methods using speakers as a sound source are limited by their frequency response and directivity. On the other hand, getting impulse responses from impulse sources typically involves a lack of repeatability, and it is usually necessary to average several measurements for each position. Through experiments in different auditoriums that recreate typical situations in which the measurement standard is applied, it is found that using impulse sources leads to greater variation in the results, especially at low frequencies. However, this prevents subsequent dispersions due to variables that this technique does not require, such as the orientation of the emitting source. These dispersions may be relevant at high frequencies exceeding the established tolerance criteria for certain parameters. Finally, a new descriptor for dodecahedral sources reflecting the influence their lack of omnidirectionality produces on measuring acoustic parameters is proposed. PMID:23862805

  6. 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.

  7. 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)

  8. 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.

  9. Impulsivity, the orbifrontal cortex and borderline personality disorder

    OpenAIRE

    Berlin, Heather; Iverson, Susan; Edmund Rolls, Susan Iverson

    2003-01-01

    ?Damage to the orbitofrontal cortex (OFC) has been associated with disinhibited or socially inappropriate behaviour and emotional irregularities in both humans and monkeys. Prominent characteristics of several personality disorder syndromes, in particular Borderline Personality Disorder (BPD), are impulsivity and affective instability. This investigation aimed to determine if certain aspects of the Borderline Personality syndrome, in particular impulsivity, are associated wit...

  10. Treatment of nerve impulse data for comparison with theory.

    Science.gov (United States)

    Knight, B W; Brodie, S E; Sirovich, L

    1979-12-01

    A procedure is given for the comparison of nerve impulse data with model predictions. This method utilizes information in the nerve impulse train that is ignored by the post-stimulus-onset histogram and thereby gives an improved signal-to-noise ratio. Comparison of observed responses in the Limulus retina with predictions derived from a detailed model gives good agreement. PMID:293698

  11. Impulsive synchronization and control of directed transport in chaotic ratchets

    International Nuclear Information System (INIS)

    The impulsive synchronization problem of two identical chaotic ratchets is investigated in this paper. We demonstrate that the impulsive method to control directed transport is applicable when there are multiple co-existing attractors in phase space transporting particles in different directions. Numerical simulations are carried out to illustrate the effectiveness of the proposed method. (general)

  12. Impulsive synchronization and control of directed transport in chaotic ratchets

    Science.gov (United States)

    Guo, Liu-Xiao; Hu, Man-Feng; Xu, Zhen-Yuan

    2010-02-01

    The impulsive synchronization problem of two identical chaotic ratchets is investigated in this paper. We demonstrate that the impulsive method to control directed transport is applicable when there are multiple co-existing attractors in phase space transporting particles in different directions. Numerical simulations are carried out to illustrate the effectiveness of the proposed method.

  13. Error Estimates for a Stochastic Impulse Control Problem

    International Nuclear Information System (INIS)

    We obtain error bounds for monotone approximation schemes of a stochastic impulse control problem. This is an extension of the theory for error estimates for the Hamilton-Jacobi-Bellman equation. We obtain almost the same estimate on the rate of convergence as in the equation without impulsions

  14. Asymptotic behavior of second-order impulsive differential equations

    Directory of Open Access Journals (Sweden)

    Haifeng Liu

    2011-02-01

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

  15. 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.

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

    Science.gov (United States)

    Ueta, Genyo; Kaneko, Shuhei; Okabe, Shigemitsu

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

  17. 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.

  18. Sodar and RASS with the use of wideband acoustic impulses

    International Nuclear Information System (INIS)

    In the paper, possibilities of high-power wideband acoustic pulses for sodar and RASS are analyzed. It is taken into account that at propagation of unfilled acoustic impulses, effects of their nonlinear interaction with the air do not reveal themselves. An engineering mathematical model is built for propagation of the acoustic impulse from the gun shot in the neutral atmosphere with regard of the divergence, classic and relaxation absorption of sound waves in the air, and values of the impulse front cross-section for radio waves are obtained. Cross-sections of impulse fronts are compared with those of the atmospheric turbulent inhomogeneities. The results of comparison have shown that the echo-signal from the impulse front exceeds in level the echo-signal from the turbulent atmospheric inhomogeneities This confirms the practical realizability of such a RASS method, that allows simplifying the RASS equipment, lowering its cost and decreasing its dimensions

  19. Chaotic attitude control of satellite using impulsive control

    International Nuclear Information System (INIS)

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

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. Impulsive moving mirror model and impulsive differential equations in Banach space

    International Nuclear Information System (INIS)

    The dependence of vacuum state energy on the distance between the uniformly relatively moving mirrors is used to calculate impulsive differential equations in Banach space. We formulate the problem of moving mirrors, possibly with suddenly change of velocity v in t=tn, n=0, 1, 2, ..., upon which quantum fields satisfy Dirichlet boundary conditions, with the associated Casimir effect, in a functional Schroedinger picture. 10 refs

  5. 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

  6. Experimental study on a plasma focus in erosion plasma accelerators. Pt. 5. On the mechanism of a plasma focus formation in a magnetoplasma compressor

    International Nuclear Information System (INIS)

    The results of experimental investigation into dynamics, microstructure and stability of consequent stages of development of heavy-current plasma-dynamical discharges in erosion type magnetoplasma compressors under the conditions of intense radiation transfer are presented. Special attention is paid to sharply non-stationary stage of plasma focus formation outside the cut of the accelerating channel and processes of secondary pinching in the second half-period of discharge current, methods of their analysis at limited possibilities of diagnostics. It is shown that at the stages of formation and quasistationary flow in the compressed zone the dominating instabilities of superheating type do not result in appearance of anomalous thermodynamical and transfer properties of non-ideal discharge plasma; thermalized in compression zone and accelerated plasma is macroscopically stable during the interaction of current envelope with relatively cold vapor followed by formation of intense shock-wave structure and force instabilities of different modes. Irrespective of chemical and ionization composition of electric-discharge plasma shown is a possibility of exercising and inertial (in combination with Hall effect) mechanism of plasma focus formation or two-stage inertial subcompression of plasma-plasma compression at the expense of Hall effect to the central cathode in the accelerating channel and additional pinching in output zet-currents that permits to provide control of dimens that permits to provide control of dimensions, dynamical and energy characteristics of plasma flow at self-coordinated introduction of energy in the zone of MHD compression

  7. Time Domain Modeling of Powerline Impulsive Noise at Its Source

    Directory of Open Access Journals (Sweden)

    Hassina Chaouche

    2011-09-01

    Full Text Available Noise characteristics of an indoor power line network strongly influence the link capability to achieve high data rates. The appliances shared with PLC modems in the same powerline network generate different types of noises, among them the impulsive noises are the main source of interference resulting in signal distortions and bit errors during data transmission. With regard to impulsive noise many models were proposed in the literature and shared the same impulsive noise definition: “unpredictable noises measured in the receiver side”. Authors are, consequently, confronted to model thousands of impulsive noises whose plurality would very likely come from the diversity of paths that the original impulsive noise took. In this paper, an innovative modelling approach is applied to impulsive noises which are studied here directly at their sources. Noise at receiver would be simply the noise model at source convolved by powerline channel block. In the new analytical model, the impulsive noise at source is described by a succession of short pulses, each modeled by a phase-shifted Gaussian. Noises at source are classified into 6 different classes [1], and a noise generator is established for each class.

  8. Stability of Impulsive Differential Equation with any Time Delay

    Directory of Open Access Journals (Sweden)

    Sanjay K. Srivastava

    2013-03-01

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

  9. Alcohol increases impulsivity and abuse liability in heavy drinking women.

    Science.gov (United States)

    Reed, Stephanie Collins; Levin, Frances R; Evans, Suzette M

    2012-12-01

    Heavy drinking has increased in recent years and has been linked to numerous health-related risks, particularly in women. A number of factors may play a role in exacerbating the risks linked to heavy drinking, such as impulsivity, which itself is related to a number of risky behaviors. The present study investigated the effects of alcohol (0, 0.5, 0.75 g/kg) on impulsivity in female heavy drinkers (n = 23) and female light drinkers (n = 23) using a double-blind, placebo-controlled outpatient design; all women were tested during follicular phase of the menstrual cycle. Each session, participants completed a range of tasks including subjective measures of abuse liability, cognitive performance tasks, three behavioral impulsivity tasks, and a risk-taking task. Alcohol increased impulsivity on the Immediate and Delayed Memory Task (IMT and DMT) and Delay Discounting task. Heavy drinkers scored higher on impulsivity self-reports and were more impulsive on the IMT and the GoStop task than light drinkers. The high dose of alcohol further increased impulsive performance on the IMT and DMT in heavy drinkers. There were no group differences or alcohol effects on the Balloon Analogue Risk Task. Alcohol increased sedative-like effects more in light drinkers and increased stimulant-like effects and alcohol liking more in heavy drinkers. In summary, female heavy drinkers are less sensitive to the negative effects of alcohol, report more positive effects of alcohol, and are more impulsive than female light drinkers. Moreover, impulsive responding was exacerbated by alcohol drinking among female heavy drinkers, indicating that women who drink at this level are at increased risk for developing alcohol use disorders and engaging in other risky behaviors, particularly after drinking. PMID:23066857

  10. 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.

  11. 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.

  12. 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.

  13. Impulsive control of chaotic systems and its applications in synchronization

    International Nuclear Information System (INIS)

    In this paper, some novel sufficient conditions for asymptotic stability of impulsive control systems are presented by comparison systems. The results are used to obtain the conditions under which the chaotic systems can be asymptotically controlled to the origin via impulsive control. Compared with some existing results, our results are more relaxed in the sense that the Lyapunov function is required to be nonincreasing only along a subsequence of switchings. Moreover, a larger upper bound of impulsive intervals for stabilization and synchronization is obtained. (general)

  14. The definition of electro impulses used in weed control

    Directory of Open Access Journals (Sweden)

    Judaev I.V.

    2008-01-01

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

  15. Impulsive control of chaotic systems and its applications in synchronization

    Science.gov (United States)

    Wu, Bo; Liu, Yang; Lu, Jian-Quan

    2011-05-01

    In this paper, some novel sufficient conditions for asymptotic stability of impulsive control systems are presented by comparison systems. The results are used to obtain the conditions under which the chaotic systems can be asymptotically controlled to the origin via impulsive control. Compared with some existing results, our results are more relaxed in the sense that the Lyapunov function is required to be nonincreasing only along a subsequence of switchings. Moreover, a larger upper bound of impulsive intervals for stabilization and synchronization is obtained.

  16. Impulse-response analysis of the market share attraction model

    OpenAIRE

    Fok, D.; Franses, Ph.H.B.F.

    1999-01-01

    We propose a simulation-based technique to calculate impulse-response functions and their confidence intervals in a market share attraction model [MCI]. As an MCI model implies a reduced form model for the logs of relative market shares, simulation techniques have to be used to obtain the impulse-responses for the levels of the market shares. We apply the technique to an MCI model for a five-brand detergent market. We illustrate how impulse-response functions can help to interpret the est...

  17. From gene to brain to behavior: schizophrenia-associated variation in AMBRA1 alters impulsivity-related traits.

    Science.gov (United States)

    Heinrich, Angela; Nees, Frauke; Lourdusamy, Anbarasu; Tzschoppe, Jelka; Meier, Sandra; Vollstädt-Klein, Sabine; Fauth-Bühler, Mira; Steiner, Sabina; Bach, Christiane; Poustka, Luise; Banaschewski, Tobias; Barker, Gareth J; Büchel, Christian; Conrod, Patricia J; Garavan, Hugh; Gallinat, Jürgen; Heinz, Andreas; Ittermann, Bernd; Loth, Eva; Mann, Karl; Artiges, Eric; Paus, Tomáš; Lawrence, Claire; Pausova, Zdenka; Smolka, Michael N; Ströhle, Andreas; Struve, Maren; Witt, Stephanie H; Schumann, Gunter; Flor, Herta; Rietschel, Marcella

    2013-09-01

    Recently, genome-wide association between schizophrenia and an intronic variant in AMBRA1 (rs11819869) was reported. Additionally, in a reverse genetic approach in adult healthy subjects, risk allele carriers showed a higher medial prefrontal cortex blood oxygen level-dependent (BOLD) response during a flanker task examining motor inhibition as an aspect of impulsivity. To test whether this finding can be expanded to further aspects of impulsivity, we analysed the effects of the rs11819869 genotype on impulsivity-related traits on a behavioral, temperament and neural level in a large sample of healthy adolescents. We consider this reverse genetic approach specifically suited for use in a healthy adolescent sample, as these individuals comprise those who will eventually develop mental disorders in which impulsivity is implicated. Healthy adolescents from the IMAGEN study were included in the neuropsychological analysis (n = 848) and a functional magnetic resonance imaging (fMRI) task (n = 512). Various aspects of impulsivity were assessed using the Temperament and Character Inventory-Revised, the Substance Use Risk Profile Scale, the Cambridge Cognition Neuropsychological Test Automated Battery, and the Stop Signal Task (SST) in the fMRI paradigm. On a behavioral level, increased delay aversion was observed in risk allele carriers. Furthermore, risk allele carriers showed a higher BOLD response in an orbito-frontal target region during the SST, which declined to trend status after Family Wise Error correction. Our findings support the hypothesis that the schizophrenia-related risk variant of rs11819869 is involved in various aspects of impulsivity, and that this involvement occurs on a behavioral as well as an imaging genetics level. PMID:23551272

  18. Peak load-impulse characterization of critical pulse loads in structural dynamics

    International Nuclear Information System (INIS)

    The P-I characterization scheme greatly facilitates specification of critical loads for structures subjected to air blast loading and is generally useful for structures subjected to pulse loads. A general feature of the P-I characterization scheme is that critical load curves are represented reasonably well by a rectangular hyperbola [(P/P0)-1][(I/I0)-1]=1, where P is the peak load, P0 the step load required to produce the critical displacement, I the impulse, area under the load-time curve, I0 the ideal (zero duration) impulse required to produce the critical displacement. This representation is useful for common structural elements such as beams, plates and shells. Some increase in accuracy is obtained by replacing the right-hand side with a constant C, determined by fitting to experimental results or to a theoretical critical load curve. A key feature of the P-I characterization scheme is that the critical load curves are not sensitive to pulse shape. The P-I characterization scheme contains the same information as the dynamic load factor (DLF). Although they contain the same information, these two characterizations emphasize different aspects. The DLF characterization displays the relation of dynamic loads to an equivalent static load. The P-I characterization displays equivalent dynamic loads in terms of peak load and impulse, the load parameters that are important at the long-duration and short-duration extremes. (Authuration and short-duration extremes. (Auth.)

  19. Early Life Stress Produces Compulsive-Like, but Not Impulsive, Behavior in Females

    Science.gov (United States)

    2015-01-01

    Adverse experiences during childhood are associated with the development of psychiatric disorders later in life. In particular, childhood abuse and neglect are risk factors for addictive disorders, such as substance misuse and pathological gambling. Impulsivity and compulsivity are key features of these disorders. Therefore, we investigated whether childhood adversity might increase vulnerability for addictive disorders through promotion of compulsive and impulsive behaviors. Rats were exposed to a brief, variable childhood or prepubertal stress protocol (Postnatal Days 25–27), and their behavior in a delay discounting task was compared with that of control animals in adulthood. Prepubertal stress produced compulsive-type behavior in females. Specifically, stressed females displayed inappropriate responses during a choice phase of the task, perseverating with nosepoke responding instead of choosing between 2 levers. Stressed females also showed learning impairments during task training. However, prepubertal stress was not associated with the development of impulsive behavior, as rates of delay discounting were not affected in either sex. Childhood adversity may contribute to the establishment and maintenance of addictive disorders by increasing perseveration in females. Perseverative behavior may therefore provide a viable therapeutic target for preventing the development of addictive disorders in individuals exposed to childhood adversity. These effects were not seen in males, highlighting sex differences in response to early life stress. PMID:26030429

  20. [Impulsivity in sexual offenders--new ideas or back to basics?].

    Science.gov (United States)

    Krasowska, Aleksandra; Jakubczyk, Andrzej; Czernikiewicz, Wies?aw Marek; Wojnar, Marcin; Nasierowski, Tadeusz

    2013-01-01

    Despite the fact that the group of sexual offenders remains a population which is still difficult to study, the results of current research are considered novel and interesting. Surprisingly, the very old descriptions applying to paraphilia, which is considered to be one of the reasons of sexual offences, appear to be accurate, especially in the context of similarities between impulsivity and pathologic sexual behaviors. Notably, the nomenclature concerning impulsivity enables a specific and reasonable description of behaviors associated with sexual offences. Moreover, the results of research studies show that it is the lack of inhibition, not pathologic arousal, which is the most important factor in the pathogenesis of forbidden sexual behaviors. In addition, it has been shown that behavioral manifestations of impulsivity (substance abuse, suicide attempts) appear commonly in sexual offenders. Mutual relationships between alcohol drinking, suicide attempts, history of child sexual abuse and sexual offences, both in symptomatologic and etiologic aspect, raise a suggestion that all these phenomena may share a common background of poor inhibitory control. PMID:24946478

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

    Science.gov (United States)

    Niu, Yu-Jun; Xu, Wei; Li, Hong-Wu

    2010-01-01

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

  2. Acoustic radiation force impulse imaging for evaluation of renal parenchyma elasticity in diabetic nephropathy.

    Science.gov (United States)

    Goya, Cemil; Kilinc, Faruk; Hamidi, Cihad; Yavuz, Alpaslan; Yildirim, Yasar; Cetincakmak, Mehmet Guli; Hattapoglu, Salih

    2015-02-01

    OBJECTIVE. The goal of this study is to evaluate the changes in the elasticity of the renal parenchyma in diabetic nephropathy using acoustic radiation force impulse imaging. SUBJECTS AND METHODS. The study included 281 healthy volunteers and 114 patients with diabetic nephropathy. In healthy volunteers, the kidney elasticity was assessed quantitatively by measuring the shear-wave velocity using acoustic radiation force impulse imaging based on age, body mass index, and sex. The changes in the renal elasticity were compared between the different stages of diabetic nephropathy and the healthy control group. RESULTS. In healthy volunteers, there was a statistically significant correlation between the shear-wave velocity values and age and sex. The shear-wave velocity values for the kidneys were 2.87, 3.14, 2.95, 2.68, and 2.55 m/s in patients with stage 1, 2, 3, 4, and 5 diabetic nephropathy, respectively, compared with 2.35 m/s for healthy control subjects. Acoustic radiation force impulse imaging was able to distinguish between the different diabetic nephropathy stages (except for stage 5) in the kidneys. The threshold value for predicting diabetic nephropathy was 2.43 m/s (sensitivity, 84.1%; specificity, 67.3%; positive predictive value, 93.1%; negative predictive value 50.8%; accuracy, 72.1%; positive likelihood ratio, 2.5; and negative likelihood ratio, 0.23). CONCLUSION. Acoustic radiation force impulse imaging could be used for the evaluation of the renal elasticity changes that are due to secondary structural and functional changes in diabetic nephropathy. PMID:25615754

  3. The Development of Reflection-Impulsivity and Cognitive Efficiency

    Science.gov (United States)

    Salkind, Neil J.; Wright, John C.

    1977-01-01

    Presents an alternative conceptual model of Reflection-Impulsivity. The alternative dimension delineates both a cognitive style and a cognitive efficiency dimension. A methodological alternative for use with the model is also presented. (BD)

  4. Gigabit impulse radio UWB signal generation and fiber transmission

    DEFF Research Database (Denmark)

    Rodes Lopez, Roberto; Gibbon, Timothy Braidwood

    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.

  5. Numerical analysis on acoustic impulse response for watermelon

    International Nuclear Information System (INIS)

    In this study, we conducted both analysis on impact pulse signal and acoustic impulse response method using numerical analysistic finite element method. Considering its velocity, density, Young's Modulus, and Poisson's Ratio, we extracted featured parameters and compared both results of analysis on impact pulse signal and numerical analysis on acoustic impulse response then we found the feature of generated acoustic sound signal by way of numerical analysis varying featured parameters and consequently intended to extract feature indices influenced on its internal maturity through analysis of acoustic impulse response. As we analyzed impact pulse signal and extracted featured parameters concerned with evaluation of its ripeness, we found the plausibility of progress on nondestructive evaluation of ripeness and adoption of numerical analysis on acoustic impulse response.

  6. 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.

  7. On coating adhesion during impulse plasma deposition

    International Nuclear Information System (INIS)

    The impulse plasma deposition (IPD) technique is the only method of plasma surface engineering (among plasma-based technologies) that allows a synthesis of layers upon a cold unheated substrate and which ensures a good adhesion. This paper presents a study of plasma impacts upon a copper substrate surface during the IPD process. The substrate was exposed to pulsed N2/Al plasma streams during the synthesis of AlN layers. For plasma–material interaction diagnostics, the optical emission spectroscopy method was used. Our results show that interactions of plasma lead to sputtering of the substrate material. It seems that the obtained adhesion of the layers is the result of a complex surface mechanism combined with the effects of pulsed plasma energy impacts upon the unheated substrate. An example of such a result is the value of the critical load for the Al2O3 layer, which was measured by the scratch-test method to be above 40 N. (paper)

  8. Jet formation from impulsive cavity collapse

    Science.gov (United States)

    Antkowiak, Arnaud; Bremond, Nicolas; Le Dizés, Stéphane; Villermaux, Emmanuel

    2006-11-01

    A cavity at a free liquid/gas interface collapsing due to an impulsive body force forms an intense concentrated jet. This is the paradigm for bubbles bursting at a liquid surface, the collapse of cavitation bubbles near a rigid boundary, collapsing voids following an impact, shaped charges, gravity waves colliding a dam, high amplitude Faraday waves, to quote a few examples among many. We address this problem by considering the axial impact of a cylindrical tube falling by gravity and filled with a liquid wetting the tube wall. Following the impact on a rigid floor, the curvature of the spherical meniscus initially fixed by the tube radius reverses violently, prelude of the birth of a rapid ascending jet. We derive the initial velocity and pressure field around the cavity just after the impact from Euler equations. They are insensitive to liquid viscosity and surface tension, consistently with detailed PIV measurements from high speed movies of the phenomenon. The extension to a cavity no more confined by rigid walls, the dynamics of the resulting jet and its final fragmentation will be considered as well.

  9. Minimum Impulse Thruster Valve Design and Development

    Science.gov (United States)

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

    2004-10-01

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

  10. Reactive high power impulse magnetron sputtering

    Science.gov (United States)

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

    2012-10-01

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

  11. Minimum impulse thruster valve design and development

    Science.gov (United States)

    Huftalen, Richard L.; Platt, Andrea L.; Parker, Morgan J.; Yankura, George A.

    2003-01-01

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

  12. 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.

  13. Manipulation of plasma grating by impulsive molecular alignment

    International Nuclear Information System (INIS)

    We experimentally demonstrated that multiphoton-ionization-induced plasma grating in air could be precisely manipulated by impulsive molecular alignment. In the linear region, the impulsively aligned molecules modulated the diffraction efficiency of the plasma grating for a time-delayed femtosecond laser pulse. In the nonlinear region, the third harmonic generation from the plasma grating was either enhanced or suppressed by following the alignment of the molecules

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

    OpenAIRE

    Va?nnia?, Eeva

    2013-01-01

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

  15. Exploiting spatiospectral correlation for impulse denoising in hyperspectral images

    Science.gov (United States)

    Aggarwal, Hemant Kumar; Majumdar, Angshul

    2015-01-01

    This paper proposes a technique for reducing impulse noise from corrupted hyperspectral images. We exploit the spatiospectral correlation present in hyperspectral images to sparsify the datacube. Since impulse noise is sparse, denoising is framed as an ?1-norm regularized ?1-norm data fidelity minimization problem. We derive an efficient split Bregman-based algorithm to solve the same. Experiments on real datasets show that our proposed technique, when compared with state-of-the-art denoising algorithms, yields better results.

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

    OpenAIRE

    Anisha K K; M.Wilscy

    2012-01-01

    Medical images are analyzed for diagnosis of various diseases. But, they are susceptible to impulse noise. Noise removal can be done much more efficiently by a combination of image filters or a composite filter,than by a single image filter. Determining the appropriate filter combination is a difficult task. In this paper, we propose a technique that uses Fuzzy Genetic Algorithm to find the optimal composite filters for removing all types of impulse noise from medical images. Here, a Fuzzy Ru...

  17. 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 ...

  18. Heritability and Longitudinal Stability of Impulsivity in Adolescence

    OpenAIRE

    Niv, Sharon; Tuvblad, Catherine; Raine, Adrian; Wang, Pan; BAKER, LAURA A.

    2011-01-01

    Impulsivity is a multifaceted personality construct that plays an important role throughout the lifespan in psychopathological disorders involving self-regulated behaviors. Its genetic and environmental etiology, however, is not clearly understood during the important developmental period of adolescence. This study investigated the relative influence of genes and environment on self-reported impulsive traits in adolescent twins measured on two separate occasions (waves) between the ages of 11...

  19. 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...

  20. An Impulse Control Disorder Case with Penile Fracture and Trichotillomania

    OpenAIRE

    Cumurcu, Birgu?l Elbozan

    2007-01-01

    Penile fractures are classically described as presenting with rapid detumescence of an erection associated with blunt trauma. This clinical finding is due to a tear in the tunica albuginea surrounding the corpora cavernosum. In this study, we report and discuss a case of trichotillomania and penile bending impulse resulting in penile fracture, which was operated in the urology clinic. The possible psychological and psychiatric problems underlying the impulsive behavior are discussed, and the ...

  1. Impulse waves at Kühtai reservoir generated by avalanches and lindslides

    OpenAIRE

    Schleiss, Anton J.; Boes, Robert M.; Fuchs, H.; Boes, M.; Pfister, Michael

    2011-01-01

    The Kühtai reservoir is planned as an addition to the existing Sellrain-Silz group of HPPs. Two natural hazards relevant in terms of potential impulse wave impact on the dam were identified: a snow avalanche near the dam axis and a possible landslide further upstream. A preliminary analytical evaluation of impulse wave heights and wave run-up based on empirical equations showed that dam overtopping could not be excluded. However, several limitations of this evaluation were not satisfied, res...

  2. 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 ...

  3. Impulse control disorders in Parkinson’s disease: recent advances

    OpenAIRE

    Voon, V; Mehta, AR; Hallett, M

    2011-01-01

    PURPOSE OF REVIEW: The aim is to review the recent advances in the epidemiology and pathophysiology of impulse control disorders (ICDs) in Parkinson's disease. RECENT FINDINGS: Large cross-sectional and case-control multicentre studies show that ICDs in Parkinson's disease are common, with a frequency of 13.6%. These behaviours are associated with impaired functioning and with depressive, anxiety and obsessive symptoms, novelty seeking and impulsivity. Behavioural subtypes demonstrate differe...

  4. 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.

  5. Complete and lag synchronization of hyperchaotic systems using small impulses

    International Nuclear Information System (INIS)

    The complete synchronization and lag synchronization of the hyperchaotic systems are restated as the impulsive control issues. Some simple and easy-to-be-verified stability criteria for impulsive control systems are derived, and then applied to synchronize and lag-synchronize the hyperchaotic Chua's oscillators. Moreover, the boundaries of the stable regions are also estimated. Some computer simulations illustrate the effectiveness of our results

  6. Asymptotic stability of a genetic network under impulsive control

    Science.gov (United States)

    Li, Fangfei; Sun, Jitao

    2010-07-01

    The study of the stability of genetic network is an important motif for the understanding of the living organism at both molecular and cellular levels. In this Letter, we provide a theoretical method for analyzing the asymptotic stability of a genetic network under impulsive control. And the sufficient conditions of its asymptotic stability under impulsive control are obtained. Finally, an example is given to illustrate the effectiveness of the obtained method.

  7. Impulsive control of projective synchronization in chaotic systems

    International Nuclear Information System (INIS)

    Scaling factor of projective synchronization in coupled partially linear chaotic systems is hardly predictable. To control projective synchronization of chaotic systems in a preferred way, an impulsive control scheme is introduced to direct the scaling factor onto a desired value. The control approach is derived from the impulsive differential equation theory. Numerical simulations on the chaotic Lorenz system are illustrated to verify the theoretical results. Furthermore, some interesting and surprising numerical results are discussed

  8. 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.

  9. 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.

  10. Effects of Electrical Stimulation with Different Impulses on Physical Characteristics of Rabbit Meat

    OpenAIRE

    H Yurmiati; GA Wiedy; S Kusmajadi

    2010-01-01

    Meat becoming less tender with age. One of the methods to increase the meat tenderness is by electrical simulation. The objective of this study was to investigate the effect of electrical simulation with different level of impulses on physical characteristics of rabbit meat. Twenty carcasses of Flemish Giant rabbit were randomly subjected into four differents treatments (impulse levels), which were control, impulse 25, impulse 50, and impulse 75. Each treatment was repeated 5 times. Measured...

  11. 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 analracks 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)

  12. 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

  13. Physical and engineering aspects in the development of a separation apparatus for magneto-plasma separation of a material into elements and their isotopes on a beam-plasma discharge base

    International Nuclear Information System (INIS)

    The review contains the authors' and literature data about the study of possibilities in the development of a magneto-plasma separation apparatus on the beam-plasma discharge (BPD) base and its implementation in the state of the art. There formulated and substantiated is the physical background for solution of such a problem concerning a conception of the project, selection of its characteristics, conditions for required plasma formation and heating which should be provided by the evolution of physical mechanisms (processes) inside the plasma leading to the effective self-excitation of microwave and high-frequency oscillations responsible for the electron- and ion heating. Comparative analysis of existing and magneto-plasma separators (MPS) and being developed ones is carried out. The problems on the separated material injection by means of the beam-plasma discharge for ion-atomic separation technologies, thermal and gas (vapor) dynamic characteristics of the phase transformation unit are considered, the capacity of MPS for production of isotopic-purity materials is estimated, and the prospects of using them for reprocessing of NW and RAW are discussed.

  14. High power impulse magnetron sputtering discharge

    International Nuclear Information System (INIS)

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

  15. Performance of children with attention deficit hyperactivity disorder (ADHD) on a test battery of impulsiveness.

    Science.gov (United States)

    Rubia, Katya; Smith, Anna; Taylor, Eric

    2007-05-01

    Children with ADHD were compared to healthy controls on a task battery of cognitive control, measuring motor inhibition (Go/No-Go and Stop tasks), cognitive inhibition (motor Stroop and Switch tasks), sustained attention and time discrimination. Children with ADHD showed an inconsistent and premature response style across all 6 tasks. In addition they showed task-specific impairments in measures of sustained attention, time discrimination, and motor inhibition, but spared cognitive inhibition. Measures of impairment correlated with behavioral hyperactivity and with each other, suggesting that they measure interrelated aspects of a multifaceted construct of cognitive impulsiveness. The task battery as a whole showed 76% correct discrimination of cases and controls. PMID:17453834

  16. Impulsividade e acidentes de trânsito / Impulsiveness and traffic accidents

    Scientific Electronic Library Online (English)

    Marcus Maximilliano, Araújo; Leandro Fernandes, Malloy-Diniz; Fábio Lopes, Rocha.

    Full Text Available CONTEXTO: As lesões por acidentes de trânsito são um problema de saúde pública e constituem uma das principais causa mortis de adultos jovens no mundo. OBJETIVO: Revisar resultados relevantes sobre a relação entre impulsividade e comportamentos de risco e acidentes de trânsito. MÉTODO: O levantament [...] o bibliográfico foi realizado nas bases MedLine, LILACS, Desastres, Cochrane Lybrary, no banco de teses da CAPES e PsycINFO, compreendendo o período de 1966 a 2006. RESULTADOS: Dos 11 estudos originais encontrados ("n" de 3806 indivíduos), seis abordaram a associação entre impulsividade e comportamento de risco no trânsito e cinco trataram da impulsividade e acidentes de trânsito. A associação entre impulsividade e correr por aventura foi observada em dois estudos e a correlação entre impulsividade e infrações em três. No desfecho acidentes, três autores mostraram associação e dois não. CONCLUSÕES: A impulsividade está associada ao comportamento de risco no trânsito, correr por aventura e infrações. A associação entre impulsividade e mais envolvimento em acidentes é controversa. Abstract in english BACKGROUND: Injuries due to road traffic accidents are a major public health problem as well as one of the main causes of death among young males aged 15 to 44 years. OBJECTIVES: This paper reviews the relation between impulsiveness and risk driving behavior and between impulsiveness and traffic acc [...] idents. METHODS: Bibliographic review. Sources: MedLine (1966 to 2006), Cochrane databases, LILACS, Desastres, PsycINFO and CAPES theses archive. RESULTS: In total, 11 original studies (n=3806). Association between impulsiveness and speeding for the thrill (02 articles), impulsiveness and driver violations (03 articles) and impulsiveness traffic road accidents (03 articles). CONCLUSIONS: The impulsiveness is associated to the risky driving behavior, "run for thrill" and "traffic violations". The association between impulsiveness and accident proness is controversal.

  17. Impulsividade e acidentes de trânsito Impulsiveness and traffic accidents

    Directory of Open Access Journals (Sweden)

    Marcus Maximilliano Araújo

    2009-01-01

    Full Text Available CONTEXTO: As lesões por acidentes de trânsito são um problema de saúde pública e constituem uma das principais causa mortis de adultos jovens no mundo. OBJETIVO: Revisar resultados relevantes sobre a relação entre impulsividade e comportamentos de risco e acidentes de trânsito. MÉTODO: O levantamento bibliográfico foi realizado nas bases MedLine, LILACS, Desastres, Cochrane Lybrary, no banco de teses da CAPES e PsycINFO, compreendendo o período de 1966 a 2006. RESULTADOS: Dos 11 estudos originais encontrados ("n" de 3806 indivíduos, seis abordaram a associação entre impulsividade e comportamento de risco no trânsito e cinco trataram da impulsividade e acidentes de trânsito. A associação entre impulsividade e correr por aventura foi observada em dois estudos e a correlação entre impulsividade e infrações em três. No desfecho acidentes, três autores mostraram associação e dois não. CONCLUSÕES: A impulsividade está associada ao comportamento de risco no trânsito, correr por aventura e infrações. A associação entre impulsividade e mais envolvimento em acidentes é controversa.BACKGROUND: Injuries due to road traffic accidents are a major public health problem as well as one of the main causes of death among young males aged 15 to 44 years. OBJECTIVES: This paper reviews the relation between impulsiveness and risk driving behavior and between impulsiveness and traffic accidents. METHODS: Bibliographic review. Sources: MedLine (1966 to 2006, Cochrane databases, LILACS, Desastres, PsycINFO and CAPES theses archive. RESULTS: In total, 11 original studies (n=3806. Association between impulsiveness and speeding for the thrill (02 articles, impulsiveness and driver violations (03 articles and impulsiveness traffic road accidents (03 articles. CONCLUSIONS: The impulsiveness is associated to the risky driving behavior, "run for thrill" and "traffic violations". The association between impulsiveness and accident proness is controversal.

  18. Impulsivity and risk taking in bipolar disorder and schizophrenia.

    Science.gov (United States)

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

    2014-01-01

    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 disorder and schizophrenia. Participants included 68 individuals with bipolar disorder, 38 with schizophrenia, and 36 healthy controls. Self-reported impulsivity was elevated in the bipolar group compared with schizophrenia patients and healthy controls, who did not differ from each other. On the risk-taking task, schizophrenia patients were significantly more risk averse than the bipolar patients and controls. Aside from the diagnostic group differences, there was a significant effect of antipsychotic (AP) medication within the bipolar group: bipolar patients taking AP medications were more risk averse than those not taking AP medications. This difference in risk taking because of AP medications was not explained by history of psychosis. Similarly, the differences in risk taking between schizophrenia and bipolar disorder were not fully explained by AP effects. Implications for clinical practice and future research are discussed. PMID:23963117

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

    Directory of Open Access Journals (Sweden)

    Khurram L. Bhatti

    2014-05-01

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

  20. 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".

  1. 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%.

  2. Open-loop dereverberation of multichannel room impulse responses

    Science.gov (United States)

    Lee, Bowon; Hasegawa-Johnson, Mark A.; Goudeseune, Camille

    2003-04-01

    We are developing the audio display for a CAVE-type virtual reality theater, a 3-m cube with displays covering all six rigid faces. The user's headgear continuously reports ear positions so headphones would be possible, but we nevertheless prefer loudspeakers because this enhances the sense of total immersion. Because sounds produced at the loudspeakers are distorted by the room impulse responses, we therefore face the problem of controlling the sound at the listener's two ears. Our proposed solution consists of open-loop acoustic point control, i.e., dereverberation. The room impulse responses from each loudspeaker to each ear of the listener are inverted using multichannel inversion methods, to create exactly the desired sound field at the listener's ears. Because the actual room impulse responses cannot be measured in real time (as the listener walks around), instead the impulse responses simulated by the image-source method is used. A new evaluation criterion is proposed to quantitatively evaluate both the simulation and the open-loop dereverberation. The actual impulse responses used for this evaluation are measured with a starter pistol, since this best approximates the point source assumed by the image-source method.

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Ma, Tie-Dong; Zhao, Fei-Ya

    2014-12-01

    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.

  5. Impulsive Noise Suppression from Images with the Noise Exclusive Filter

    Directory of Open Access Journals (Sweden)

    Alç? Mustafa

    2004-01-01

    Full Text Available A novel impulsive noise elimination filter, entitled noise exclusive filter (NEF, which shows a high performance at the restoration of images distorted by impulsive noise, is proposed in this paper. NEF uses chi-square goodness-of-fit test in order to detect the corrupted pixels more accurately. Simulation results show that the proposed filter achieves a superior performance compared with the other filters mentioned in this paper in terms of noise suppression and detail preservation, particularly when the noise density is very high. The proposed method also achieves the robustness and detail preservation perfectly for a wide range of impulsive noise density. NEF provides efficient filtering performance with reduced computational complexity.

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

    Directory of Open Access Journals (Sweden)

    Anisha K K

    2011-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Benjamin Oyediran Oyelami

    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.

  8. Cognition and removal of impulse noise with uncertainty.

    Science.gov (United States)

    Zhou, Zhe

    2012-07-01

    Uncertainties are the major inherent feature of impulse noise. This fact makes image denoising a difficult task. Understanding the uncertainties can improve the performance of image denoising. This paper presents a novel adaptive detail-preserving filter based on the cloud model (CM) to remove impulse noise. It is called the CM filter. First, an uncertainty-based detector identifies the pixels corrupted by impulse noise. Then, a weighted fuzzy mean filter is applied to remove the noise candidates. The experimental results show that, compared with the traditional switching filters, the CM filter makes a great improvement in image denoising. Even at a noise level as high as 95%, the CM filter still can restore the image with good detail preservation. PMID:22389145

  9. Impulsivity and the self-defeating behavior of narcissists.

    Science.gov (United States)

    Vazire, Simine; Funder, David C

    2006-01-01

    Currently prominent models of narcissism (e.g., Morf and Rhodewalt, 2001) primarily explain narcissists' self-defeating behaviors in terms of conscious cognitive and affective processes. We propose that the disposition of impulsivity may also play an important role. We offer 2 forms of evidence. First, we present a meta-analysis demonstrating a strong positive relationship between narcissism and impulsivity. Second, we review and reinterpret the literature on 3 hallmarks of narcissism: self-enhancement, aggression, and negative long-term outcomes. Our reinterpretation argues that impulsivity provides a more parsimonious explanation for at least some of narcissists' self-defeating behavior than do existing models. These 2 sources of evidence suggest that narcissists' quest for the status and recognition they so intensely desire is thwarted, in part, by their lack of the self-control necessary to achieve those goals. PMID:16768652

  10. 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)

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Efficiency of fusion under impulse-periodic laser welding

    International Nuclear Information System (INIS)

    The causes of substantial difference in the penetration depth in laser beam welding under impulse-periodic and continuous conditions at identical mean power are considered. It is shown that one of the cause is the difference in power supply conditions, which are more favourable for impulse-periodic conditions due to the absence of beam screening by plasma and a liquid interlayer during a moment of pulse radiation. The second and more substantial cause is the high efficiency of fusion at considerable power density in the interaction front, being characteristic for impulse-periodic heating conditions. Numerical and analytical sulutions of the problem on heat transfer, confirming correctness of the given solution, are suggested

  16. Impulse Electrotherapy in Reduction Treatment of the Tuboperitoneal Steri

    Directory of Open Access Journals (Sweden)

    T.E. Belousova

    2010-03-01

    Full Text Available Aim of investigation is assessment of the impulse electrotherapy clinical effectiveness in a complex treatment of patients with the tuboperitoneal sterility.Materials and methods. A complex clinicolaboratory examination of 114 patients with the tuboperitoneal sterility (TPS is made. All the females were divided into 3 groups. The females underwent a laparoscopic operation and ultrasonic therapy in the impulse mode to a suprapubic zone in the early postoperative period (10—15 procedures in the 1st control group (n=30. The females underwent a laparoscopic operation and a course of impulse electrotherapy with the «SCANAR-1-HT» apparatus with a use of vaginal electrode (10—15 procedures in the 2nd group (n=42. A course of impulse electrotherapy was conducted without a vaginal electrode use (10—15 procedures in the 3d group (n=42. Two parameters were considered at assessment of the female reproductive function reduction: a conservation of the uterine tube permeability after laparoscopy and a spontaneous pregnancy beginning. A hysterosalpingography was made in all the patients in 2—3 months after a reduction treatment.Results. An impulse electrotherapy used in the early reduction period after a laparoscopic operation in patients with the tuboperitoneal sterility improves the uterine tube permeability conservation values by 28%, the fertility values — by 20% compared to a group, where an ultrasonic therapy in the impulse mode was used in the early reduction period.The proposed method normally effects the lipid peroxidation and antioxidant system state, a homeostasis, leads to a hemodynamics normalization in the small pelvis organs, a decrease of the organism regulatory mechanism tension degree, a decrease of a sympathetic nervous system influence and increase of a parasympathetic nervous system tonus, has an expressed psychocorrugating effect.

  17. Detection of Impulsive Light-Like Signals in General Relativity

    OpenAIRE

    Barrabès, C.; Hogan, P. A.

    2001-01-01

    The principal purpose of this paper is to study the effect of an impulsive light-like signal on neighbouring test particles. Such a signal can in general be unambiguously decomposed into a light-like shell of null matter and an impulsive gravitational wave. Our results are: (a) If there is anisotropic stress in the light-like shell then test particles initially moving in the signal front are displaced out of this 2-surface after encountering the signal; (b) For a light-like ...

  18. On the impulse approximation for the (n,p) reaction

    International Nuclear Information System (INIS)

    The impulse approximation used in the analysis of the co-planar symmetric (p,2p) reaction has been examined quantitatively. It is found that for low binding energy nucleons (approximately 10 MeV) this approximation is valid beyond 200 MeV while for high binding energy (approximately 40 MeV) it is valid beyond 250 MeV. Below these energies the peak cross-section in the impulse approximation could be as big an overestimate as a factor of 1.5. (author)

  19. 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

  20. Impulsive Exponential Consensus of Multi-agent Nonlinear Fuzzy Systems

    Directory of Open Access Journals (Sweden)

    Liping Zhang

    2013-01-01

    Full Text Available In this study, we investigate the problem of impulsive exponential consensus of multi-agent systems, where each agent is represented by an identical T-S fuzzy model. Firstly, a fuzzy impulsive control protocol is designed for networks with fixed topology based on the local information of agents. Then sufficient conditions in terms of linear matrix equalities are given to guarantee the exponential consensus of the multi-agent fuzzy systems. Numerical simulations show the effectiveness of our theoretical results.

  1. Fast Impulse Noise Removal from Highly Corrupted Images

    CERN Document Server

    Hosseini, Hossein

    2011-01-01

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

  2. Filtered backprojection for modifying the impulse response of circular tomosynthesis

    International Nuclear Information System (INIS)

    A filtering technique has been developed to modify the three-dimensional impulse response of circular motion tomosynthesis to allow the generation of images whose appearance is like those of some other imaging geometries. In particular, this technique can reconstruct images with a blurring function which is more homogeneous for off-focal plane objects than that from circular tomosynthesis. In this paper, we describe the filtering process, and demonstrate the ability to alter the impulse response in circular motion tomosynthesis from a ring to a disk. This filtering may be desirable because the blurred out-of-plane objects appear less structured

  3. Research in impulse joining of self pierce riveting

    OpenAIRE

    Hahn, O.; Neugebauer, Reimund; Leuschen, G.; Kraus, C.; Mauermann, R.

    2008-01-01

    Results are shown in impulse joining of aluminium sheets with self-pierce-riveting. Two institutes are testing impulse-riveting with different setting velocities of the punch - up to 10 m/s by using pneumatic cylinders and about 100 m/s by using a propellant charge. One aim focus consists in riveting without a C-frame against a flat anvil instead of using a C-frame with a contoured die. So accessibility is increased and disadvantages of occurring misalignments are avoidable. The strength prop...

  4. Impulsive formation control using orbital energy and angular momentum vector

    Science.gov (United States)

    Choi, Yoonhyuk; Mok, Sunghoon; Bang, Hyochoong

    2010-09-01

    This paper presents a multi-impulsive formation control strategy using orbit energy-matching and relative angular momentum vector between leader and follower satellites. These conservative parameters (energy and angular momentum) provide analytical and global solutions for orbital maneuver design without relying on Gauss variational equations. The relationship with orbit element differences is discussed in the simplifying assumptions. The proposed approach is free from small variation assumptions, so that it is suitable for handling even the case of large error corrections. General limitations of impulse control and associated compensation maneuvers are also addressed.

  5. DDCS interface system for safety logic with Fine Impulse Test

    International Nuclear Information System (INIS)

    DDCS interface system for Safety Logic with Fine Impulse Test (SLFIT) is developed for communicating reactor trip annunciations and logic fault annunciations to Distributed Digital Control System (DDCS). DDCS Interface system acquires Reactor trip annunciations at various stages of Safety Logic. It acquires various faults of Safety Logic and FIT logic. Trip annunciations, Logic faults and health status are scanned periodically and sent to Distributed Digital Control System. This paper describes the input signals, output packets, processing logic, architecture and software design of DDCS interface system for Safety Logic with Fine Impulse Test. (author)

  6. GENERAL: Bifurcation control and chaos in a linear impulsive system

    Science.gov (United States)

    Jiang, Gui-Rong; Xu, Bu-Gong; Yang, Qi-Gui

    2009-12-01

    Bifurcation control and the existence of chaos in a class of linear impulsive systems are discussed by means of both theoretical and numerical ways. Chaotic behaviour in the sense of Marotto's definition is rigorously proven. A linear impulsive controller, which does not result in any change in one period-1 solution of the original system, is proposed to control and anti-control chaos. The numerical results for chaotic attractor, route leading to chaos, chaos control, and chaos anti-control, which are illustrated with two examples, are in good agreement with the theoretical analysis.

  7. Second-order neutral impulsive stochastic evolution equations with delay

    Science.gov (United States)

    Ren, Yong; Sun, Dandan

    2009-10-01

    In this paper, we study the second-order neutral stochastic evolution equations with impulsive effect and delay (SNSEEIDs). We establish the existence and uniqueness of mild solutions to SNSEEIDs under non-Lipschitz condition with Lipschitz condition being considered as a special case by the successive approximation. Furthermore, we give the continuous dependence of solutions on the initial data by means of corollary of the Bihari inequality. An application to the stochastic nonlinear wave equation with impulsive effect and delay is given to illustrate the theory.

  8. Alcohol Increases Impulsivity and Abuse Liability in Heavy Drinking Women

    OpenAIRE

    Reed, Stephanie Collins; Levin, Frances R.; Evans, Suzette M

    2012-01-01

    Heavy drinking has increased in recent years and has been linked to numerous health-related risks, particularly in women. A number of factors may play a role in exacerbating the risks linked to heavy drinking, such as impulsivity, which itself is related to a number of risky behaviors. The present study investigated the effects of alcohol (0, 0.5, 0.75 g/kg) on impulsivity in female heavy drinkers (n = 23) and female light drinkers (n = 23) using a double-blind, placebo-controlled outpatient ...

  9. The Impulse Response of an Exponential Assembly

    International Nuclear Information System (INIS)

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

  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. Interval oscillation criteria for second-order forced delay differential equations under impulse effects

    OpenAIRE

    Qiaoluan Li; Wing-Sum Cheung

    2013-01-01

    We establish some oscillation criteria for a forced second-order differential equation with impulses. These results extend some well-known results for forced second-order impulsive differential equations with delay.

  12. 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.

  13. 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

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

    OpenAIRE

    Lai Florence DM; Ip Alison KY; Lee Tatia MC

    2011-01-01

    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 gam...

  15. 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...

  16. 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...

  17. 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...

  18. Information criteria for impulse response function matching estimation of DSGE models

    OpenAIRE

    Hall, Alastair; Inoue, Atsushi; Nason, James M.; Rossi, Barbara

    2008-01-01

    We propose a new information criterion for impulse response function matching estimators (IRFMEs) of the structural parameters of dynamic stochastic general equilibrium (DSGE) macroeconomic models. An advantage of our procedure is that it allows researchers to select the impulse responses that are most informative about DSGE model parameters and ignore the rest. The idea of tossing out superfluous impulse responses motivates our Redundant Impulse Response Selection Criterion (RIRSC). The RIRS...

  19. Generating chaos for discrete time-delayed systems via impulsive control

    Science.gov (United States)

    Guan, Zhi-Hong; Liu, Na

    2010-03-01

    Generating chaos for a class of discrete time-delayed systems via impulsive control is investigated in this paper. With the augmented matrix method, the time-delay impulsive systems can be transformed into a new class of linear discrete impulsive systems. Based on the largest Lyapunov exponent and the boundedness of the systems, some theoretical results about the chaotification for the discrete impulsive systems with time delay are derived and an example is given to visualize the satisfactory control performance.

  20. Controllability and Observability of Linear Time-Varying Impulsive Systems on Time Scales

    Science.gov (United States)

    Zhang, Kexue; Liu, Xinzhi

    2011-11-01

    This paper studies the problems of controllability and observability of a general linear time-varying impulsive control systems on time scales. By proposing a formula of variation of parameters for this type of systems on time scales, several necessary and sufficient criteria on controllability and observability of the impulsive control system on time scales are established. It is shown that the classical results about controllability and observability of linear continuous impulsive systems can be generalized to the impulsive systems on time scales.

  1. An Impulsive Two-Prey One-Predator System with Seasonal Effects

    OpenAIRE

    Hunki Baek

    2009-01-01

    In recent years, the impulsive population systems have been studied by many researchers. However, seasonal effects on prey are rarely discussed. Thus, in this paper, the dynamics of the Holling-type IV two-competitive-prey one-predator system with impulsive perturbations and seasonal effects are analyzed using the Floquet theory and comparison techniques. It is assumed that the impulsive perturbations act in a periodic fashion, the proportional impulses (the chemical controls) for all species...

  2. Diagnosis and treatment of impulse control disorders in patients with movement disorders

    OpenAIRE

    Mestre, Tiago A.; Strafella, Antonio P.; Thomsen, Teri; Voon, Valerie; Miyasaki, Janis

    2013-01-01

    Impulse control disorders are a psychiatric condition characterized by the failure to resist an impulsive act or behavior that may be harmful to self or others. In movement disorders, impulse control disorders are associated with dopaminergic treatment, notably dopamine agonists (DAs). Impulse control disorders have been studied extensively in Parkinson’s disease, but are also recognized in restless leg syndrome and atypical Parkinsonian syndromes. Epidemiological studies suggest younger ag...

  3. Cone-valued impulsive differential and integrodifferential inequalities

    Directory of Open Access Journals (Sweden)

    Sam Olatunji Ale

    2005-06-01

    Full Text Available In this paper, we present impulsive analogues of the Gronwall-Bellman inequalities. Conditions for the existence of maximal solutions of some integrodifferential equations are obtained by finding upper bounds for these inequalities. Using monotone iterative techniques and a fixed point theorem, we obtained a priori estimates for the inequalities.

  4. Cone-valued impulsive differential and integrodifferential inequalities

    OpenAIRE

    Sam Olatunji Ale; Benjamin Oyediran Oyelami; Maligie S. Sesay

    2005-01-01

    In this paper, we present impulsive analogues of the Gronwall-Bellman inequalities. Conditions for the existence of maximal solutions of some integrodifferential equations are obtained by finding upper bounds for these inequalities. Using monotone iterative techniques and a fixed point theorem, we obtained a priori estimates for the inequalities.

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

    Science.gov (United States)

    Amita, Hidetoshi; Kawamori, Ai; Matsushima, Toshiya

    2010-04-23

    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 competition (coincident feeding without interruption) and scrounging (gaining food without pecking bead) separately. To examine the effects of risk/noise that individual chicks experienced in competition, the food amount varied randomly in trials according to a binomial distribution around the expected mean. Perceived competition primarily contributed to the influence on the impulsive choice, whereas the contribution of scrounging was weaker. Collection risk did not explain the social influences since the perceived competition was not accompanied by actual interruption of the delayed food reward. The risk owing to variable food per se did not cause impulsive choices. Coincident foraging during competition is thought to play a critical role. PMID:19906684

  6. 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)

  7. Radiative muon capture: impulse approximation and the continuity equation

    International Nuclear Information System (INIS)

    A modified form of the impulse-approximation effective Hamiltonian of the nuclear radiative muon capture is developed. The electromagnetic-current continuity equation to minimise the meson-exchange-current corrections is used. The method is directly applicable to other radiative reactions with two currents, e. g., to the pion photoproduction process

  8. Bifurcations of planar Hamiltonian systems with impulsive perturbation

    CERN Document Server

    Hu, Zhaoping; Romanovski, Valery G

    2011-01-01

    In this paper, by means of the Melnikov functions we consider bifurcations of harmonic or subharmonic solutions from a periodic solution of a planar Hamiltonian system under impulsive perturbation. We give some sufficient conditions under which a harmonic or subharmonic solution exists.

  9. Impulsivity, aggression and suicidal behavior in unipolar and bipolar disorders

    OpenAIRE

    Perroud, Nader Ali; Baud, Patrick; Mouthon, Dominique; Courtet, Philippe; Malafosse, Alain

    2011-01-01

    Predictors of suicidal behaviors (SB) in bipolar (BD) and major depressive disorder (MDD) patients are poorly understood. It has been recognized that behavioral dysregulation characterizes SB with traits of impulsivity and aggression being particularly salient. However, little is known about how these traits are segregated among mood disorder patients with and without a history of suicide attempt (SA).

  10. 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

  11. A study on iterative learning control for impulsive differential equations

    Science.gov (United States)

    Liu, Shengda; Wang, JinRong; Wei, Wei

    2015-07-01

    In order to tracking the desired discontinuous output trajectory, we explore P-type iterative learning control law with initial state learning for impulsive differential equations. The sufficient conditions of open-loop and closed-loop iterative learning schemes in the sense of L2 -norm are established. Finally, an example is given to illustrate our theoretical results.

  12. Global asymptotic stability of delay BAM neural networks with impulses

    International Nuclear Information System (INIS)

    The global asymptotic stability of delay bi-directional associative memory neural networks with impulses are studied by constructing suitable Lyapunov functional. Sufficient conditions, which are independent to the delayed quantity, are obtained for the global asymptotic stability of the neural networks. Some illustrative examples are given to demonstrate the effectiveness of the obtained results

  13. Impulse response measurements with an off-line cross correlator

    International Nuclear Information System (INIS)

    The impulse responses of simulated systems have been computed by off-line cross-correlation of the system input and output signals. The input test signal consisted of a discrete interval binary code whose autocorrelation was a triangular pulse at zero lag. The main object of the experiments was to study the inaccuracies introduced in ideal, noise free systems by determining the impulse response digitally from sampled versions of the system input and output signals. A second object was to determine the error introduced by adding controlled amounts of uncorrelated noise at the system outputs. The experimental results showed that for signal to noise ratios greater than 10:1 in the mean square sense, the impulse responses may be determined with reasonable accuracy using only one cycle of the binary code. The method lends itself to on-line computation of system impulse responses. The latter could be used to monitor the stability of the system or to determine control parameters in an adaptive control system. (author)

  14. Volume expansion of nonmyelinated nerve fibers during impulse conduction.

    OpenAIRE

    Tasaki, I.; Byrne, P. M.

    1990-01-01

    Nonmyelinated nerve fibers undergo rapid volume expansion while carrying an impulse. This volume expansion is incurred as a consequence of a lateral expansion of the excited portion of the fibers, where the superficial layer is transformed into a low-density structure.

  15. Filtering of the Color Images Distorted by Impulse Noise

    Directory of Open Access Journals (Sweden)

    C. Stupak

    2001-09-01

    Full Text Available The paper deals with color image filtering distorted by impulsenoise. The component, transformation, and vector filtering areanalyzed. The filters are evaluated besides the classical criteria(mean absolute error and mean square error, and by the colordifference criterion. Moreover, use of the impulse detectors in thecolor image filtration is analyzed.

  16. Impulse Correlation Ratio in Solving Multiple Impact Problems

    Science.gov (United States)

    Hurmuzlu, Yildirim; Ceanga, Viorel

    In this chapter we consider first the most basic multi-impact system, the so called "Newton's Cradle". The task of developing an analytical method to predict the post impact velocities of the balls in the cradle has baffled investigators in the field of impact research for many years. The impulse based rigid body as well as the alternative time based approaches have failed to produce valid solutions to this problem. A new method that produces energetically consistent solutions to the problem is presented. The method is based on the traditional impulse-momentum based rigid body approach. We do, however, resolve the non-uniqueness difficulty in the rigid body approach by introducing a new constant called the Impulse Correlation Ratio. Finally, we verify our method by conducting a set of experiments and comparing the theoretical predictions with the experimental outcomes. The second part of the chapter deals with a second class of multi-impact problems. Such problems arise when a rigid body strikes an external surface at a point when it is resting on the surface at another point. The impulse correlation ratio is also applied to solve this problem. The method produces physically valid and energetically consistent solutions to the problem.

  17. Some Applications of Impulse Control in Mathematical Finance

    OpenAIRE

    Korn, Ralf

    1999-01-01

    We consider three applications of impulse control in financial mathematics, a cash management problem, optimal control of an exchange rate, and portfolio optimisation under transaction costs. We sketch the different ways of solving these problems with the help of quasi-variational inequalities. Further, some viscosity solution results are presented.

  18. 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.

  19. Simulation Platform for Wireless Sensor Networks Based on Impulse Radio Ultra Wide Band

    CERN Document Server

    Berthe, Abdoulaye; Dragomirescu, Daniela; Plana, Robert

    2010-01-01

    Impulse Radio Ultra Wide Band (IR-UWB) is a promising technology to address Wireless Sensor Network (WSN) constraints. However, existing network simulation tools do not provide a complete WSN simulation architecture, with the IR-UWB specificities at the PHYsical (PHY) and the Medium Access Control (MAC) layers. In this paper, we propose a WSN simulation architecture based on the IR-UWB technique. At the PHY layer, we take into account the pulse collision by dealing with the pulse propagation delay. We also modelled MAC protocols specific to IRUWB, for WSN applications. To completely fit the WSN simulation requirements, we propose a generic and reusable sensor and sensing channel model. Most of the WSN application performances can be evaluated thanks to the proposed simulation architecture. The proposed models are implemented on a scalable and well known network simulator: Global Mobile Information System Simulator (GloMoSim). However, they can be reused for all other packet based simulation platforms.

  20. 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.

  1. Interactions among impulsiveness, testosterone, sex hormone binding globulin and androgen receptor gene CAG repeat length.

    Science.gov (United States)

    Aluja, Anton; García, Luís F; Martí-Guiu, Maite; Blanco, Eduardo; García, Oscar; Fibla, J; Blanch, Àngel

    2015-08-01

    Impulsive personality phenotype has been extensively related with genetic and hormonal factors. This study has two objectives: a) to analyse the interactions between testosterone levels and CAG repeat length polymorphism as a modulator of androgen receptor (AR) sensitivity with regard to impulsiveness traits, and b) to evaluate the contribution of other biological variables as Luteinising Hormone, Follicle Stimulating Hormone, Sex Hormone Binding Globulin (LF, FSH, SHBG) and albumin in the relationship between testosterone levels and AR CAG length polymorphism with impulsiveness. A sample of 105 healthy males (mean age 26.71±9.68 SEM) was analysed resulting in three groups of subjects according to CAG repeat lengths. Impulsiveness was measured through the Barratt's Impulsiveness Personality Scale, including three components: Motor Impulsiveness, Cognitive Impulsiveness and Non-Planning Impulsiveness. A series of ANOVAS and linear regression models predicting impulsiveness scales were conducted. Age, hormones, CAG repeat length and hormone×CAG repeat interactions were included in the regression models as independent variables. Results show that subjects with short or medium CAG repeat length tended to show higher impulsiveness phenotypes compared to long CAG repeat. The interaction between Free Testosterone and CAG, and between SHBG and CAG accounted for differences on impulsiveness (R: .47, R(2): .22 and R: .43; R(2): .18, respectively).This pattern was especially observed for the short CAG repeat group and Motor Impulsiveness. PMID:25890275

  2. Impulsive Stabilization for a Class of Neural Networks with Both Time-Varying and Distributed Delays

    OpenAIRE

    Lizi Yin; Xiaodi Li

    2009-01-01

    The impulsive control method is developed to stabilize a class of neural networks with both time-varying and distributed delays. Some exponential stability criteria are obtained by using Lyapunov functionals, stability theory, and control by impulses. A numerical example is also provided to show the effectiveness and feasibility of the impulsive control method.

  3. Impulsive Stabilization for a Class of Neural Networks with Both Time-Varying and Distributed Delays

    Directory of Open Access Journals (Sweden)

    Lizi Yin

    2009-01-01

    Full Text Available The impulsive control method is developed to stabilize a class of neural networks with both time-varying and distributed delays. Some exponential stability criteria are obtained by using Lyapunov functionals, stability theory, and control by impulses. A numerical example is also provided to show the effectiveness and feasibility of the impulsive control method.

  4. A system of impulsive degenerate nonlinear parabolic functional-differential inequalities

    Directory of Open Access Journals (Sweden)

    Ludwik Byszewski

    1995-01-01

    Full Text Available A theorem about a system of strong impulsive degenerate nonlinear parabolic functional-differential inequalities in an arbitrary parabolic set is proved. As a consequence of the theorem, some theorems about impulsive degenerate nonlinear parabolic differential inequalities and the uniqueness of a classical solution of an impulsive degenerate nonlinear parabolic differential problem are established.

  5. Male axillary extracts modify the affinity of the platelet serotonin transporter and impulsiveness in women.

    Science.gov (United States)

    Marazziti, Donatella; Masala, Irene; Baroni, Stefano; Polini, Margherita; Massimetti, Gabriele; Giannaccini, Gino; Betti, Laura; Italiani, Paola; Fabbrini, Laura; Caglieresi, Carolina; Moschini, Cecilia; Canale, Domenico; Lucacchini, Antonio; Mauri, Mauro

    2010-06-16

    The presence of functional pheromones in axillary extracts in humans is still matter of debate. Scattered data suggest that unidentified human axillary compounds with pheromonal activity may influence mood and this may occur, perhaps, through the modulation of the serotonin (5-HT) system that has been linked to mood by several findings. Therefore, the aim of this study was to assess the possible changes of a peripheral marker of the 5-HT system, i.e., the platelet 5HT transporter, and of some psychological tests, in a group of women who were exposed to male axillary extracts (group 1). A matched group of women who underwent an exposure to a neutral solution, were used as control subjects (group 2). The 5-HT transporter was evaluated by means of the specific binding of (3)H-paroxetine ((3)H-Par) to platelet membranes, as well as by means of (3)H-5-HT reuptake in whole platelets, at baseline (T0) and 1h after the stimulation (T1). The following tests were used: the "Experiences in Close Relationships" questionnaire (ECR), the latest version of the Barratt Impulsiveness Scale (BIS-11) and the Structured Clinical Interview for Mood Spectrum, self-reported version. The dissociation constant (Kd) of (3)H-Par binding showed a significant decrease at T1 only in the women exposed to male axillary extracts, as compared with baseline values, while the Bmax and (3)H-5-HT reuptake parameters did not show any change in both groups. The correlation analyses showed that at T0, the Kd values correlated significantly and positively with the factor of motor impulsiveness in all subjects. Two factors of the BIS-11, in particular, the attentional and the motor impulsiveness were significantly lower at T1 in the group 1. Further, at T1 and still in the group 1, a significant and positive correlation was measured between the Kd values and two ECR attachment styles, the secure and preoccupied, as well as with the ECR anxiety scale. Taken together, these findings suggest that the application of male axillary extracts to women may modify the affinity of their platelet 5-HT transporter, as well as of some impulsiveness and romantic attachment characteristics. The substances responsible for this effect remain to be identified. PMID:20347855

  6. The nature of impulsivity: visual exposure to natural environments decreases impulsive decision-making in a delay discounting task.

    Science.gov (United States)

    Berry, Meredith S; Sweeney, Mary M; Morath, Justice; Odum, Amy L; Jordan, Kerry E

    2014-01-01

    The benefits of visual exposure to natural environments for human well-being in areas of stress reduction, mood improvement, and attention restoration are well documented, but the effects of natural environments on impulsive decision-making remain unknown. Impulsive decision-making in delay discounting offers generality, predictive validity, and insight into decision-making related to unhealthy behaviors. The present experiment evaluated differences in such decision-making in humans experiencing visual exposure to one of the following conditions: natural (e.g., mountains), built (e.g., buildings), or control (e.g., triangles) using a delay discounting task that required participants to choose between immediate and delayed hypothetical monetary outcomes. Participants viewed the images before and during the delay discounting task. Participants were less impulsive in the condition providing visual exposure to natural scenes compared to built and geometric scenes. Results suggest that exposure to natural environments results in decreased impulsive decision-making relative to built environments. PMID:24841421

  7. The Nature of Impulsivity: Visual Exposure to Natural Environments Decreases Impulsive Decision-Making in a Delay Discounting Task

    Science.gov (United States)

    Berry, Meredith S.; Sweeney, Mary M.; Morath, Justice; Odum, Amy L.; Jordan, Kerry E.

    2014-01-01

    The benefits of visual exposure to natural environments for human well-being in areas of stress reduction, mood improvement, and attention restoration are well documented, but the effects of natural environments on impulsive decision-making remain unknown. Impulsive decision-making in delay discounting offers generality, predictive validity, and insight into decision-making related to unhealthy behaviors. The present experiment evaluated differences in such decision-making in humans experiencing visual exposure to one of the following conditions: natural (e.g., mountains), built (e.g., buildings), or control (e.g., triangles) using a delay discounting task that required participants to choose between immediate and delayed hypothetical monetary outcomes. Participants viewed the images before and during the delay discounting task. Participants were less impulsive in the condition providing visual exposure to natural scenes compared to built and geometric scenes. Results suggest that exposure to natural environments results in decreased impulsive decision-making relative to built environments. PMID:24841421

  8. Sociodemographic, neuropsychiatric and cognitive characteristics of pathological gambling and impulse control disorders NOS in Parkinson's disease.

    Science.gov (United States)

    Pontieri, Francesco E; Assogna, Francesca; Pellicano, Clelia; Cacciari, Claudia; Pannunzi, Sara; Morrone, Annalucia; Danese, Emanuela; Caltagirone, Carlo; Spalletta, Gianfranco

    2015-01-01

    Despite of previous evidence supporting the association between impulse control disorder (ICD) and several demographic, clinical and therapeutic features in Parkinson's disease (PD), the relationships between pathological gambling (PG) or other variants of ICD (ICD-NOS) and specific neuropsychiatric or cognitive domains are not entirely defined. In this study, 155 PD patients without dementia or cognitive impairment underwent: i. the ICD diagnoses, using the Questionnaire for Impulsive-Compulsive Disorders, ii. the mood and anxiety disorders diagnoses, according to the DSM-IV-TR criteria, and iii. a comprehensive battery for measuring severity of psychopathology and neuropsychology domains. Patients were divided in those with pathological gambling (PG), ICDs not otherwise specified (ICD-NOS), or the lack of ICD (No-ICD). There was a progression in age and age at onset from the younger PG subjects throughout ICD-NOS to No-ICD. PG and ICD-NOS subjects had longer disease duration and were taking significantly higher dosages of antiparkinsonian drugs than No-ICD ones. PG subjects had significantly higher severity of depressive and anxious symptoms with respect to the other 2 groups. Both PG and ICD-NOS subjects suffer from increased severity of psychotic symptoms than No-ICD ones. The 3 groups did not differ in any cognitive measure. Our results support the concept that the different sociodemographic and neuropsychiatric profiles of PD patients are associated with different ICDs. Moreover, we clearly demonstrate the lack of relationship between ICD and cognitive performances in undemented PD patients. PMID:25435085

  9. 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

  10. 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

  11. Near-Capacity Coding for Discrete Multitone Systems with Impulse Noise

    OpenAIRE

    Kschischang Frank R; Yu Wei; Ardakani Masoud

    2006-01-01

    We consider the design of near-capacity-achieving error-correcting codes for a discrete multitone (DMT) system in the presence of both additive white Gaussian noise and impulse noise. Impulse noise is one of the main channel impairments for digital subscriber lines (DSL). One way to combat impulse noise is to detect the presence of the impulses and to declare an erasure when an impulse occurs. In this paper, we propose a coding system based on low-density parity-check (LDPC) codes and bit-in...

  12. The Moderating Effect of Social Support on the Relationship Between Impulsivity and Suicide in Rural China.

    Science.gov (United States)

    Zhang, Jie; Lin, Lin

    2015-07-01

    This study was to investigate the relationship among social support, impulsivity, and suicide, so as to test the hypothesis that social support moderates the effect of impulsivity on suicide for the rural young suicides in China. Subjects were 392 consecutively recruited suicides aged 15-34 years and 416 community controls of the same age range sampled in China. The case-control data were obtained using psychological autopsy. The results showed that high social support had the protective effect among individuals with low impulsivity. It can be concluded that impulsivity is a potential area for further study of suicidal behavior. The suicide prevention efforts in rural China may address impulsivity. PMID:25540027

  13. Stability analysis of nonlinear stochastic differential delay systems under impulsive control

    Science.gov (United States)

    Li, Chunxiang; Sun, Jitao

    2010-02-01

    In this Letter, we study the stability of nonlinear stochastic differential delay systems under impulsive control. First, we construct an impulsive control for a nonlinear stochastic differential delay system. Then, the equivalent relation between the stability of the nonlinear stochastic differential delay system under impulsive control and that of a corresponding nonlinear stochastic differential delay system without impulses is established. Third, some sufficient conditions ensuring various stabilities of the nonlinear stochastic differential delay systems under impulsive control are obtained. Finally, an example is also discussed to illustrate the effectiveness of the obtained results.

  14. Impulsive synchronization of Roessler systems with parameter driven by an external signal

    International Nuclear Information System (INIS)

    In this Letter, an impulsive control scheme is presented to control two uncoupled identical Roessler systems. By driving the parameter of Roessler systems using external chaotic signal or periodic signal, chaotic synchronization and periodic synchronization can be implemented. This is a special impulsive control, but by using the existing results of impulsive control theory, a less conservative estimation of the upper bound of the impulse interval is given, which can guarantee the global asymptotical stability for the impulsive synchronization of Roessler systems. Numerical results are in accord with our estimation

  15. Analysis and design for unified exponential stability of three different impulsive T-S fuzzy systems

    International Nuclear Information System (INIS)

    Three different forms of impulsive T-S models are discussed in this paper; the first one is described by a nonlinear impulsive control system represented by T-S model, while the second one is expressed as a state feedback impulsive control plant and the third one is depicted by a hybrid system. A simple and unified Lyapunov-based stability criterion is proposed to guarantee the exponential stability of closed-loop impulsive fuzzy systems. Such criterion is expressed in the form of linear matrix inequalities and the corresponding design algorithms are presented. Several numerical simulations are shown to demonstrate how the proposed controllers can stabilize these impulsive fuzzy systems.

  16. Minimal Nonnegative Solution of Nonlinear Impulsive Differential Equations on Infinite Interval

    Directory of Open Access Journals (Sweden)

    Feng Meiqiang

    2011-01-01

    Full Text Available The cone theory and monotone iterative technique are used to investigate the minimal nonnegative solution of nonlocal boundary value problems for second-order nonlinear impulsive differential equations on an infinite interval with an infinite number of impulsive times. All the existing results obtained in previous papers on nonlocal boundary value problems are under the case of the boundary conditions with no impulsive effects or the boundary conditions with impulsive effects on a finite interval with a finite number of impulsive times, so our work is new. Meanwhile, an example is worked out to demonstrate the main results.

  17. The mediating role of anger in the relationship between PTSD symptoms and impulsivity.

    Science.gov (United States)

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

    2015-03-01

    Research indicates a significant relationship between posttraumatic stress disorder (PTSD) and anger (Olatunji, Ciesielski, & Tolin, 2010; Orth & Wieland, 2006). Individuals may seek urgent coping to deal with the distress of anger, which is a mobilizing and action-oriented emotion (Novaco & Chemtob, 2002); possibly in the form of impulsive actions consistent with impulsivity's association with anger (Milligan & Waller, 2001; Whiteside & Lynam, 2001). This could be 1 of the explanations for the relationship between PTSD and impulsivity (Kotler, Julian, Efront, & Amir, 2001; Ledgerwood & Petry, 2006). The present study assessed the mediating role of anger between PTSD (overall scores and subscales of arousal and negative alterations in mood/cognitions) and impulsivity, using gender as a covariate of impulsivity. The PTSD Checklist for Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5), Dimensions of Anger Reaction scale-5, and the UPPS Impulsivity Scale were administered to a sample of 244 undergraduate students with a trauma history. Results based on 1000 bootstrapped samples indicated significant direct effects of PTSD (overall and 2 subscales) on anger, of anger on impulsivity, and of PTSD (overall and 2 subscales) on impulsivity. Further, anger significantly mediated the relationship between PTSD (overall and 2 subscales) and impulsivity, consistent with the hypothesized models. Results suggest that impulsivity aims at coping with distressing anger, possibly explaining the presence of substance usage, and other impulsive behaviors in people with PTSD. Further, anger probably serves as a mobilizing and action-oriented emotion coupled with PTSD symptoms. PMID:25793689

  18. Medium-frequency impulsive-thrust-activated liquid hydrogen reorientation with Geyser

    Science.gov (United States)

    Hung, R. J.; Shyu, K. L.

    1992-01-01

    Efficient technique are studied for accomplishing propellant resettling through the minimization of propellant usage through impulsive thrust. A comparison between the use of constant-thrust and impulsive-thrust accelerations for the activation of propellant resettlement shows that impulsive thrust is superior to constant thrust for liquid reorientation in a reduced-gravity environment. This study shows that when impulsive thrust with 0.1-1.0-, and 10-Hz frequencies for liquid-fill levels in the range between 30-80 percent is considered, the selection of 1.0-Hz-frequency impulsive thrust over the other frequency ranges of impulsive thrust is the optimum. Characteristics of the slosh waves excited during the course of 1.0-Hz-frequency impulsive-thrust liquid reorientation were also analyzed.

  19. Stability of delayed memristive neural networks with time-varying impulses.

    Science.gov (United States)

    Qi, Jiangtao; Li, Chuandong; Huang, Tingwen

    2014-10-01

    This paper addresses the stability problem on the memristive neural networks with time-varying impulses. Based on the memristor theory and neural network theory, the model of the memristor-based neural network is established. Different from the most publications on memristive networks with fixed-time impulse effects, we consider the case of time-varying impulses. Both the destabilizing and stabilizing impulses exist in the model simultaneously. Through controlling the time intervals of the stabilizing and destabilizing impulses, we ensure the effect of the impulses is stabilizing. Several sufficient conditions for the globally exponentially stability of memristive neural networks with time-varying impulses are proposed. The simulation results demonstrate the effectiveness of the theoretical results. PMID:25206936

  20. Synchronization of stochastic dynamical networks under impulsive control with time delays.

    Science.gov (United States)

    Zhang, Wenbing; Tang, Yang; Miao, Qingying; Fang, Jian-An

    2014-10-01

    In this paper, the stochastic synchronization problem is studied for a class of delayed dynamical networks under delayed impulsive control. Different from the existing results on the synchronization of dynamical networks under impulsive control, impulsive input delays are considered in our model. By assuming that the impulsive intervals belong to a certain interval and using the mathematical induction method, several conditions are derived to guarantee that complex networks are exponentially synchronized in mean square. The derived conditions reveal that the frequency of impulsive occurrence, impulsive input delays, and stochastic perturbations can heavily affect the synchronization performance. A control algorithm is then presented for synchronizing stochastic dynamical networks with delayed synchronizing impulses. Finally, two examples are given to demonstrate the effectiveness of the proposed approach. PMID:25291731

  1. 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.

  2. 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.)

  3. Effects of Electrical Stimulation with Different Impulses on Physical Characteristics of Rabbit Meat

    Directory of Open Access Journals (Sweden)

    H Yurmiati

    2010-05-01

    Full Text Available Meat becoming less tender with age. One of the methods to increase the meat tenderness is by electrical simulation. The objective of this study was to investigate the effect of electrical simulation with different level of impulses on physical characteristics of rabbit meat. Twenty carcasses of Flemish Giant rabbit were randomly subjected into four differents treatments (impulse levels, which were control, impulse 25, impulse 50, and impulse 75. Each treatment was repeated 5 times. Measured variables were pH, tenderness, water holding capacity, and cooking lose. The results showed that different levels of electrical stimulation had significant effects on the physical characteristics of rabbit meat. Higher impulse level caused lower ultimate pH and more tender meat. Overall, the best physical characteristics of rabbit meat was obtained from electrical stimulation with impulse level of 50. (Animal Production 12(2: 124-127 (2010Key Words : Meat becoming less tender with age. One of the methods to increase the meat tenderness is by electrical simulation. The objective of this study was to investigate the effect of electrical simulation with different level of impulses on physical characteristics of rabbit meat. Twenty carcasses of Flemish Giant rabbit were randomly subjected into four differents treatments (impulse levels, which were control, impulse 25, impulse 50, and impulse 75. Each treatment was repeated 5 times. Measured variables were pH, tenderness, water holding capacity, and cooking lose. The results showed that different levels of electrical stimulation had significant effects on the physical characteristics of rabbit meat. Higher impulse level caused lower ultimate pH and more tender meat. Overall, the best physical characteristics of rabbit meat was obtained from electrical stimulation with impulse level of 50. (Animal Production 12(2: 124-127 (2010Key Words : electrical stimulation, tenderness, rabbit, meat

  4. 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...

  5. Experimental single-impulse magnetic focusing of launched cold atoms

    CERN Document Server

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

    2007-01-01

    Three-dimensional magnetic focusing of cold atoms with a single magnetic impulse has been observed for the first time. We load 7x10^7 85-Rb atoms into a magneto-optical trap, precool the atoms with optical molasses, then use moving molasses to launch them vertically through 20.5cm to the apex of flight. In transit the atoms are optically pumped, prior to the single magnetic lens impulse that occurs 16.5cm above the MOT. Fluorescence images at the apex of flight characterise the widths of the focussed cloud. Results were obtained for four different configurations of the baseball lens, which tuned the relationship between the axial and radial frequencies of the lens. Compact focused clouds were seen for all four configurations.

  6. Clinical spectrum of impulse control disorders in Parkinson's disease.

    Science.gov (United States)

    Weintraub, Daniel; David, Anthony S; Evans, Andrew H; Grant, Jon E; Stacy, Mark

    2015-02-01

    Impulse control disorders (ICDs), including compulsive gambling, buying, sexual behavior, and eating, are a serious and increasingly recognized psychiatric complication in Parkinson's disease (PD). Other impulsive-compulsive behaviors (ICBs) have been described in PD, including punding (stereotyped, repetitive, purposeless behaviors) and dopamine dysregulation syndrome (DDS; compulsive PD medication overuse). ICDs have been most closely related to the use of dopamine agonists (DAs), perhaps more so at higher doses; in contrast, DDS is primarily associated with shorter-acting, higher-potency dopaminergic medications, such as apomorphine and levodopa. Possible risk factors for ICDs include male sex, younger age and younger age at PD onset, a pre-PD history of ICDs, and a personal or family history of substance abuse, bipolar disorder, or gambling problems. Given the paucity of treatment options and potentially serious consequences, it is critical for PD patients to be monitored closely for development of ICDs as part of routine clinical care. PMID:25370355

  7. Quasifree proton knockout reaction in the distorted wave impulse approximation

    International Nuclear Information System (INIS)

    We investigate the applicability of the distorted wave impulse approximation on the factorization assumption for the (p,2p) reaction in the lower incident energy. We calculate contour maps of analyzing powers and cross sections for the /sup 12/C(p-arrow-right,2p) reaction at an incident energy E/sub p/ = 84 MeV using distorted wave impulse approximation including the spin-orbit interaction for the distorted waves. The proton-proton t matrix elements are calculated with the effective nucleon-nucleon interaction by Love-Franey taking account of the off-shell effect. Our calculations agree well with both experimental analyzing power and cross section data on the whole region of the contour maps

  8. 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

  9. The reflection of impulses from a nonlinear random sea

    Science.gov (United States)

    Jackson, F. C.

    1979-01-01

    A model of the reflection of radar impulses from the sea at near-vertical incidence is used to account for non-Gaussian ocean waves statistics. The joint probability density function (pdf), of wave height and slope, is calculated according to the theory of Longuet-Higgins (1963) on the distribution of variables in a 'weakly nonlinear' random era. The long-crested approximation is made, a Phillips wave spectrum is assumed, and the Gram-Charlier series is truncated after skewness terms. It is found that the height and height-slope skewness coefficients bear the ratio 1:2 and that the derived impulse response and conditional cross section versus wave height are in excellent agreement with previous observations. Finally, it is suggested that the empirically determined and theoretically predicted sea state bias be corrected for in the routine processing of satellite radar altimeter data.

  10. Evaluation of an Impulse Gravity Generator Based Beamed Propulsion Concept

    CERN Document Server

    Modanese, G; Modanese, Giovanni; Taylor, Chris Y.

    2002-01-01

    This paper analyzes the suitability of a beamed propulsion concept having properties consistent with the impulse gravity generator described by Podkletnov et al. [physics/0108005]. The use of this propulsion concept for orbital maneuver, Earth-to-orbit, interplanetary, and interstellar applications based on presently available experimental results and theory is considered, and areas for future research needed to better characterize this phenomenon are discussed. A beam of radiation or particles with the properties described for the impulse gravity generator would appear to be an excellent candidate for use in beamed spacecraft propulsion. Besides the usual benefits of beamed propulsion, it would not need sails or other special spacecraft components to function, could safely provide high accelerations to delicate components, and might operate at higher efficiencies than other beamed propulsion concepts.

  11. Review of Impulse Noise Removal from Digital Video

    Directory of Open Access Journals (Sweden)

    RAVINDRA LUHACH

    2013-06-01

    Full Text Available 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 is one such noise which may corrupt the frames of a digital video during acquisition, transmission over a noisy channel or in storage etc. This paper discussed in details about the color video processing and various schemes for removal of impulse noise for digital video.

  12. IMPULSE NOISE REMOVAL FROM MAMMOGRAM IMAGES USING COMBINER APPROACH

    Directory of Open Access Journals (Sweden)

    I. Laurence Aroquiaraj

    2010-10-01

    Full Text Available 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 noise quite well. New Filter II is configured using midpoint filter, a median smoother of window size 3x3, the high pass filter and the combiner. Both the filters are shown to exhibit good response at the image boundaries (edges. The proposed filters are evaluated for their performance on mammogram test image and the results obtained are included. Keywords: Median filter, Midpoint filter, Nonlinear filters, Nonlinear high pass filter, combiner

  13. Simulation Analysis and Design for the Pressure Impulse Test

    Directory of Open Access Journals (Sweden)

    Yuan Zhaohui

    2012-01-01

    Full Text Available The pressure impulse test system is a complex nonlinear system; its control methods are very different from the traditional linear systems. The difficulty of its analysis focused on the physical realization of the entire system and mathematical model on complex pipeline system. We analyze the composition and principles of the entire test system, detailed study the basic equation of unsteady flow and do the static design which provides parameters for the dynamic simulation. Method of characteristics is used to establish the mathematical model. Then we analyze the transient process of the test system with the model, main analyze the affecting factors of water hammer wave-shaped through simulation. Finally, verify the correctness of simulation analysis model and ensure the impulse test can be successfully completed through the test of our main specimen -retractable actuator of landing gear with different combinations of key parameters.

  14. Rapid-response impulsivity: Definitions, measurement issues, and clinical implications.

    Science.gov (United States)

    Hamilton, Kristen R; Littlefield, Andrew K; Anastasio, Noelle C; Cunningham, Kathryn A; Fink, Latham H L; Wing, Victoria C; Mathias, Charles W; Lane, Scott D; Schütz, Christian G; Swann, Alan C; Lejuez, C W; Clark, Luke; Moeller, F Gerard; Potenza, Marc N

    2015-04-01

    Impulsivity is a multifaceted construct that is a core feature of multiple psychiatric conditions and personality disorders. However, progress in understanding and treating impulsivity is limited by a lack of precision and consistency in its definition and assessment. Rapid-response impulsivity (RRI) represents a tendency toward immediate action that occurs with diminished forethought and is out of context with the present demands of the environment. Experts from the International Society for Research on Impulsivity (InSRI) met to discuss and evaluate RRI measures in terms of reliability, sensitivity, and validity, with the goal of helping researchers and clinicians make informed decisions about the use and interpretation of findings from RRI measures. Their recommendations are described in this article. Commonly used clinical and preclinical RRI tasks are described, and considerations are provided to guide task selection. Tasks measuring two conceptually and neurobiologically distinct types of RRI, "refraining from action initiation" (RAI) and "stopping an ongoing action" (SOA) are described. RAI and SOA tasks capture distinct aspects of RRI that may relate to distinct clinical outcomes. The InSRI group recommends that (a) selection of RRI measures should be informed by careful consideration of the strengths, limitations, and practical considerations of the available measures; (b) researchers use both RAI and SOA tasks in RRI studies to allow for direct comparison of RRI types and examination of their associations with clinically relevant measures; and (c) similar considerations be made for human and nonhuman studies in an effort to harmonize and integrate preclinical and clinical research. (PsycINFO Database Record PMID:25867840

  15. Performance analysis of adaptive lattice filters for impulsive signals

    OpenAIRE

    Kahaei, M. H.; Deriche, M.; Boashash, B.

    1997-01-01

    This paper shows that the a-stable distributions may be used to characterise the statistical behaviour of the impulsive phenomena. (Additional details can be found in the comprehensive book on Time-Frequency Signal Analysis and Processing (see http://www.elsevier.com/locate/isbn/0080443354). In addition, the most recent upgrade of the original software package that calculates Time-Frequency Distributions and Instantaneous Frequency estimators can be downloaded from the web site: www.ti...

  16. A Different Cameras Image Impulse Noise Removal Technique

    OpenAIRE

    Lakshmanan, S.; Mythili, C.; Kavitha, Dr V.

    2012-01-01

    Digital Cameras which capture images in directly in digital form. Digital Images are mostly often corrupted by impulse noises. It is affected by sharp & characteristics of the image signal. So the image processing scheme should be one of the important part in any vision application permitting to suppress noise& improve the imageperformances without any noises. This demands to have several filtering schemes such as fuzzy & non-fuzzy are used. In this paper, propose 3 step fuzzy filter is used ...

  17. Self-control: teaching tolerance for delay in impulsive children.

    OpenAIRE

    Schweitzer, J. B.; Sulzer-Azaroff, B

    1988-01-01

    We investigated a procedure to increase the selection of larger, more delayed reinforcers (i.e., more advantageous in the long run) over smaller immediate reinforcers, in an effort to increase a key aspect of self-control in children. Six preschoolers, including one comparison subject, identified by their teachers as impulsive, were preassessed and found consistently to select smaller immediate reinforcers over larger, more delayed ones. The teaching procedure consisted of gradually increasin...

  18. Behavioural Testing for the Study of Impulsivity in Rats

    OpenAIRE

    PALASANTZA, ATHANASIA

    2014-01-01

    The present work aims to prepare a study that will investigate the role of serotonin in respect to impulsive behaviour in rats. The methodology followed employs behavioural testing, based on operant conditioning, which will be later combined with optogenetic stimulations. The stimulations will be applied to the animals in order to influence their serotonergic system. For the implementation of this project, an experimental set up was built that consists of an operant behavioural box, connected...

  19. 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.

  20. Effectiveness of Distance-Decreasing Attacks Against Impulse Radio Ranging

    OpenAIRE

    Flury, Manuel; Poturalski, Marcin; Papadimitratos, Panos; Hubaux, Jean-Pierre; Le Boudec, Jean-Yves

    2010-01-01

    We expose the vulnerability of an emerging wireless ranging technology, impulse radio ultra-wide band (IR-UWB), to distance-decreasing attacks on the physical communication layer (PHY). These attacks violate the security of secure ranging protocols that allow two wireless devices to securely estimate the distance between them, with the guarantee that the estimate is an upper-bound on the actual distance. Such protocols serve as crucial building blocks in security-sensitive applications such a...

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

    OpenAIRE

    Mengfan Cheng; Hanping Hu

    2012-01-01

    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...

  2. 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...

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

    OpenAIRE

    Venkatesan, S.; Usa, S.

    2005-01-01

    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 th...

  4. Numerical method for impulse control of Piecewise Deterministic Markov Processes

    CERN Document Server

    de Saporta, Benoîte

    2010-01-01

    This paper presents a numerical method to calculate the value function for a general discounted impulse control problem for piecewise deterministic Markov processes. Our approach is based on a quantization technique for the underlying Markov chain defined by the post jump location and inter-arrival time. Convergence results are obtained and more importantly we are able to give a convergence rate of the algorithm. The paper is illustrated by a numerical example.

  5. Optimal control problem for impulsive systems with integral boundary conditions

    Science.gov (United States)

    Ashyralyev, Allaberen; Sharifov, Y. A.

    2012-08-01

    In the present work the optimal control problem is considered, when the state of the system is described by the impulsive differential equations with integral boundary conditions. Applying the Banach contraction principle the existence and uniqueness of solution is proved for the corresponding boundary problem by the fixed admissible control. The first and second variation of the functional is calculated. Various necessary conditions of optimality of the first and second order are obtained by the help of the variation of the controls.

  6. 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 ...

  7. Treatment of Inattention, Overactivity, and Impulsiveness in Autism Spectrum Disorders

    OpenAIRE

    Aman, Michael G.; Farmer, Cristan A.; Hollway, Jill; Arnold, L. Eugene

    2008-01-01

    We reviewed the recent literature on medicines used to manage inattention, impulsiveness, and overactivity in children with pervasive developmental disorders (autistic disorder, pervasive developmental disorder not otherwise specified, Asperger’s disorder) using computer searches of pharmacological studies. A substantial number of reports were identified and summarized. The literature tends to be dominated by uncontrolled studies, although the number of controlled trials is growing. The fin...

  8. SSICM (Spin Stabilized Impulsively Controlled Missile) guidance and control concept

    Science.gov (United States)

    Howell, W. M.

    1985-09-01

    The guidance scheme utilizing wide beam width semiactive RF sensors, a precision roll attitude reference, and a controlled grade pitch, yaw and roll rate gyros to deliver high quality homing guidance information to a spin stabilized controlled missile is presented. A filtering system is utilized to eliminate errors caused by body roll signals generated due to the spin of the missiles. The nutational motion is used to calibrate the sensors. Impulsive maneuvers are utilized to intercept incoming ballistic targets.

  9. Stochastic Impulse Control and Asset Allocation with Liquidity Breakdowns

    OpenAIRE

    Diesinger, Peter

    2009-01-01

    Continuous stochastic control theory has found many applications in optimal investment. However, it lacks some reality, as it is based on the assumption that interventions are costless, which yields optimal strategies where the controller has to intervene at every time instant. This thesis consists of the examination of two types of more realistic control methods with possible applications. In the first chapter, we study the stochastic impulse control of a diffusion process. We suppose that t...

  10. RFI mitigation at Nançay Observatory: Impulsive Signal Processing

    OpenAIRE

    Ait-Allal, Dalal; Weber, Rodolphe; Dumez-viou, Cedric

    2010-01-01

    The observation of known pulsars (pulsar timing) or the search for new pulsars can be limited by radio frequency interference (RFI) generated by Telecommunication activity. In this paper, we propose several RFI mitigation techniques to cope with impulsive and/or narrow band RFI. For pulsar timing, we have implemented, a pulse blanker and a cyclostationary blanker, both in real time. For pulsar search, we propose a new approach which combines a hardware-efficient search method and some RFI mit...

  11. 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...

  12. Statistically-Efficient Filtering in Impulsive Environments: Weighted Myriad Filters

    Directory of Open Access Journals (Sweden)

    Gonzalez Juan G

    2002-01-01

    Full Text Available Linear filtering theory has been largely motivated by the characteristics of Gaussian signals. In the same manner, the proposed Myriad Filtering methods are motivated by the need for a flexible filter class with high statistical efficiency in non-Gaussian impulsive environments that can appear in practice. Myriad filters have a solid theoretical basis, are inherently more powerful than median filters, and are very general, subsuming traditional linear FIR filters. The foundation of the proposed filtering algorithms lies in the definition of the myriad as a tunable estimator of location derived from the theory of robust statistics. We prove several fundamental properties of this estimator and show its optimality in practical impulsive models such as the -stable and generalized- . We then extend the myriad estimation framework to allow the use of weights. In the same way as linear FIR filters become a powerful generalization of the mean filter, filters based on running myriads reach all of their potential when a weighting scheme is utilized. We derive the "normal" equations for the optimal myriad filter, and introduce a suboptimal methodology for filter tuning and design. The strong potential of myriad filtering and estimation in impulsive environments is illustrated with several examples.

  13. Quaternion-based color image filtering for impulsive noise suppression

    Science.gov (United States)

    Jin, Lianghai; Liu, Hong; Xu, Xiangyang; Song, Enmin

    2010-10-01

    It is difficult to precisely detect all impulsive noise in color images due to the nonstationarity caused by edges and fine details. For many pixels, we can not absolutely classify them as noisy or noise-free, but can only describe them using the likelihood that they are corrupted by impulsive noise. Based on this consideration, we present a new filtering solution to removing impulsive noise from color images. The proposed method first utilizes the unit transforms of quaternions to represent the chromaticity difference of two color pixels, and then divides the image into noise-free and possible noisy pixels. Finally it performs adaptive weighted vector median filtering operations on only the possible noisy pixels to suppress noise. The new weighting mechanism is based on a joint spatial/quaternion-chromaticity criterion, which ensures that pixels with different contamination likelihoods have different contributions to the filter's output. The extensive simulation results indicate that the proposed method significantly outperforms some other well-known multichannel filtering techniques.

  14. Spatial impulse response of a rectangular double curved transducer

    DEFF Research Database (Denmark)

    Bæk, David; Jensen, JØrgen Arendt

    2012-01-01

    Calculation of the pressure field from transducers having both a convex and a concave surface geometry is a complicated assignment that often is accomplished by subdividing the transducer surface into smaller flat elements of which the spatial impulse response is known. This method is often seen applied to curved transducers because an analytical solution is un-known. In this work a semi-analytical algorithm for the exact solution to a first order in diffraction effect of the spatial impulse response of rectangular shaped double curved transducers is presented. The algorithm and an approximation of it are investigated. The approximation reformulates the algorithm to an analytically integrable expression which is computationally efficient to solve. Simulation results are compared with the simulation software Field II. Calculating the response from 200 different points yields a mean error for the different approximations ranging from 0.03 % to 0.8 % relative to a numerical solution for the spatial impulse response. It is shown that the presented algorithm gives consistent results with Field II for a linear flat, a linear focused, and a convex non-focused element. Best solution was found to be 0.01 % with a three-point Taylor expansion.

  15. Separation Control in a Multistage Compressor Using Impulsive Surface Injection

    Science.gov (United States)

    Wundrow, David W.; Braunscheidel, Edward P.; Culley, Dennis E.; Bright, Michelle M.

    2006-01-01

    Control of flow separation using impulsive surface injection is investigated within the multistage environment of a low speed axial-flow compressor. Measured wake profiles behind a set of embedded stator vanes treated with suction-surface injection indicate significant reduction in flow separation at a variety of injection-pulse repetition rates and durations. The corresponding total pressure losses across the vanes reveal a bank of repetition rates at each pulse duration where the separation control remains nearly complete. This persistence allows for demands on the injected-mass delivery system to be economized while still achieving effective flow control. The response of the stator-vane boundary layers to infrequently applied short injection pulses is described in terms of the periodic excitation of turbulent strips whose growth and propagation characteristics dictate the lower bound on the band of optimal pulse repetition rates. The eventual falloff in separation control at higher repetition rates is linked to a competition between the benefits of pulse-induced mixing and the aggravation caused by the periodic introduction of low-momentum fluid. Use of these observations for impulsive actuator design is discussed and their impact on modeling the time-average effect of impulsive surface injection for multistage steady-flow simulation is considered.

  16. 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.)

  17. 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...

  18. Mechanisms of impulsive magnetic reconnection: Global and local aspects

    International Nuclear Information System (INIS)

    The global and local aspects of mechanisms of impulsive magnetic reconnection are discussed focusing on results from a dedicated laboratory experiment, MRX (Magnetic Reconnection Experiment), as well as fusion experiments. Possible application of the present analysis to reconnection phenomena in solar and space plasmas is also discussed. An external force which drives internal current in a fusion plasma causes magnetic flux to accumulate in a core section of the plasma (flux build-up). When the flux build-up generates a magnetic profile that satisfies a condition for a global magnetohydrodynamic instability to develop, reconnection takes place in an induced current layer generated by the instability leading to a global self-organization of the plasma. Generally the flux build-up phase is significantly longer than the reconnection time, ?H >> ?Rec, thus making the waveform of flux evolution or other plasma parameters sawtooth shaped. In the reconnection layer of collisionless plasmas, the two fluid dynamics would lead to the formation of a narrow electron current channel which tends to become unstable against micro-instabilities, leading to an unsteady or impulsive reconnection. A common feature of impulsive reconnection after flux build-up is presented.

  19. Fundamental Insulation Characteristics and Impulse Ratio of CO2 Gas

    Science.gov (United States)

    Koshino, Naoto; Kinoshita, Osamu; Hayakawa, Naoki; Goshima, Hisashi; Okabe, Shigemitsu; Morii, Hiroshi; Okubo, Hitoshi

    SF6 gas has been used as an excellent insulating and arc-quenching gas for electric power apparatus such as SF6 gas insulated switchgear (GIS). However, since SF6 gas was specified to be a greenhouse gas because of its high global warming potential (GWP), environmental-friendly gases or gas mixtures alternative to SF6 gas are strongly required to be developed. Especially, the development of insulation gases without SF6 gas is an important task for the future electric power system. We focused our research on CO2 gas and CO2-based gas mixtures such as CO2/O2, CO2/N2 with small GWP as SF6 substitutes, and investigated partial discharge (PD) and breakdown (BD) characteristics under lightning impulse and ac voltage applications. In this paper, PD inception electric field (PDIE), BD electric field (BDE) and the impulse ratio were obtained in CO2, N2, SF6 gases and CO2-based gas mixtures, and discharge mechanisms of CO2 gas were discussed. Experimental results revealed that impulse ratio in CO2 gas was higher than those in SF6 and N2 gases, and dielectric-coating effect in CO2 gas was higher than that in SF6 gas. These results were attributed to the lower generation probability of initial electrons in CO2 gas.

  20. Fermi-LAT Observation of Impulsive Solar Flares

    CERN Document Server

    Omodei, N; Pesce-Rollins, M

    2013-01-01

    The Fermi Large Area Telescope (LAT) is the most sensitive instrument ever deployed in space for observing gamma-ray emission >100 MeV. This sensitivity has enabled the LAT to detect gamma-ray emission from the Sun during quiescent periods from pions produced by cosmic-ray protons interacting in the solar atmosphere and from cosmic-ray electrons interacting with solar optical photons. The LAT has detected high-energy gamma-ray emission associated with GOES M-class and X-class X-ray flares accompanied by coronal mass ejections and solar energetic particle events. In a number of cases, LAT has detected gamma rays with energies up to several hundreds of MeV during the impulsive phase and gamma rays up to GeV energies sustained for several hours after the impulsive phase. This presentation focuses on observations in the impulsive emission phase in solar flares, including the modest GOES M2-class flare at SOL2010-06-12T0057 and more recent detections, such as the bright X-class flares of March 2012.