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1

Variable Specific Impulse Magnetoplasma Rocket Engine  

Science.gov (United States)

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

Chang-Diaz, Franklin R. (Inventor)

2002-01-01

2

Evolutionary Development of High Specific Impulse Electric Thruster Technology.  

Science.gov (United States)

Electric propulsion flight and technology demonstrations conducted primarily by Europe, Japan, China, the U.S., and the USSR are reviewed. Evolutionary mission applications for high specific impulse electric thruster systems are discussed, and the status ...

J. S. Sovey J. A. Hamley M. J. Patterson V. K. Rawlin R. M. Myers

1992-01-01

3

The evolutionary development of high specific impulse electric thruster technology  

Energy Technology Data Exchange (ETDEWEB)

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

Sovey, J.S.; Hamley, J.A.; Patterson, M.J.; Rawlin, V.K.; Meyers, R.M.

1992-03-01

4

The evolutionary development of high specific impulse electric thruster technology  

Science.gov (United States)

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.

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

1992-01-01

5

Coaxial plasma thrusters for high specific impulse propulsion  

Science.gov (United States)

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.

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

1991-01-01

6

Solar-powered rocket engine optimization for high specific impulse  

Science.gov (United States)

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

Pande, J. Bradley

1993-11-01

7

HTS Magnets for Advanced Magnetoplasma Space Propulsion Applications  

Energy Technology Data Exchange (ETDEWEB)

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.

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

1999-07-12

8

Behavioural characterisation of high impulsivity on the 5-choice serial reaction time task: specific deficits in 'waiting' versus 'stopping'.  

Science.gov (United States)

Impulsivity is a core deficit of a number of neuropsychiatric disorders including attention-deficit hyperactivity disorder (ADHD), anti-social conduct disorder and drug addiction. Recent research has highlighted the multifaceted nature of impulsivity and the myriad of putative neural and psychological mechanisms thought to underpin behavioural syndromes of impaired self-control. Here we report a novel conceptualisation of impulsivity based on 'waiting' and 'stopping' efficiency with explanatory value in defining the psychological and neural basis of impulsivity and the high co-morbidity of brain disorders such as ADHD and drug addiction. Rats selected for high levels of impulsivity on a reaction time task analogous to the continuous performance test in humans exhibited correspondingly high levels of impulsive decision-making on a delay-of-reward task. The same rats, however, were unimpaired on a stop-signal task requiring inhibition of an already initiated motor response. The specific nature of this deficit in 'waiting impulsivity' was confirmed by unimpaired acquisition of appetitive Pavlovian conditioning, a putative ancillary measure of impulsive behaviour. These findings are significant in light of recent evidence linking impulsivity in rats to high levels of cocaine self-administration and development of compulsive cocaine seeking behaviour. We thus suggest that an inability to bridge delays to future rewards and reward-related stimuli is a candidate behavioural endophenotype that pre-disposes to clinical psychopathology. PMID:18940201

Robinson, E S J; Eagle, D M; Economidou, D; Theobald, D E H; Mar, A C; Murphy, E R; Robbins, T W; Dalley, J W

2009-01-23

9

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

Science.gov (United States)

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

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

2001-04-01

10

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

International Nuclear Information System (INIS)

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

2008-04-28

11

The Application of Gridded Ion Thrusters to High Thrust, High Specific Impulse Nuclear-Electric Missions  

Science.gov (United States)

Gridded ion thrusters are usually regarded as very efficient devices which can operate at high values of specific impulse (SI), of the order of 2800 to 5000 s, but with an inherently low thrust and thrust density. However, this latter limitation is due to the restricted power available from present spacecraft. It is shown in this paper that a very much enhanced thrust density can be provided if a nuclear fission power source is utilised, with an electrical output in the 100 kW to multi-MW range, and if higher values of SI can be employed. In that case, use can be made of a 4-grid ion extraction and acceleration system, permitting present thrust densities in the range 0.1 to 0.9 mN/cm2 to be increased to as much as 28 mN/cm2. Corresponding values of SI depend critically upon the propellant used and vary from about 8000 s to as high as 150,000 s. As an example of a possible application of this technology, a manned mission to Mars is considered, which employs existing space vehicles and launchers to the maximum possible extent in order to minimise cost. It is shown that such a mission is viable if a nuclear reactor system with an electrical output of about 1 MW is available, with a mass-to-power ratio of less than 20 kg/kW.

Fearn, D. G.

12

Impulsivity, emotion regulation, and developmental psychopathology: specificity versus generality of linkages.  

Science.gov (United States)

Impulsivity, closely related to the construct of response (dis)inhibition, is central to conceptions of both attention-deficit/hyperactivity (ADHD) and aggressive-spectrum or disruptive behavior disorders. The multifaceted nature of inhibitory deficits requires careful specification in any explanatory accounts of psychopathology. A host of brain regions and neural interconnections are involved in response inhibition; neural models are likely to be complex at the levels of neurotransmitter systems and white-matter tracts. Despite the substantial heritability of ADHD and the substantial continuity of early-onset forms of aggression, developmental processes (including gene-environment correlations and interactions) and transactional models are crucial to the unfolding of regulated versus dysregulated behavioral outcomes. Thus, stressful prenatal and childhood environments must be investigated with as much precision as genetic loci and neural pathways. Differentiating executive inhibition (believed to be largely dopaminergic and frontal/frontal-striatal in nature) from motivational inhibition (believed to be largely noradrenergic/serotonergic and limbic in nature) is necessary to distinguish subtypes of youth with attentional and aggressive problems, and to differentiate key etiologic processes. Indeed, the executive function deficits in children with ADHD appear to independent of their emotion dysregulation, which is specific to an aggressive subgroup. Sex differences in response inhibition and sex differences in its linkages to psychopathology are relatively unexplored. For progress in subsequent research to occur, the following are required: precision in measurement at both biological and behavioral levels; contrasts with clinical comparison samples and comorbid groups (as well as normal control samples); prospective longitudinal investigations; and attention to both developmental processes and contextual variables, including stressful life events, socialization practices, and cultural parameters. PMID:14998881

Hinshaw, Stephen P

2003-12-01

13

Ion acoustic solitons in a warm magnetoplasma  

International Nuclear Information System (INIS)

Kalita and Bujarbarua [J. Phys. A: Math. Gen. 16, 439 (1983)] obtained a set of equations to describe the nonlinear propagation of ion acoustic waves in a warm magnetoplasma and made a numerical study of these equations for particular values of the physical parameters. In this paper a rigorous and general analytical study is presented. Some simple necessary and sufficient conditions for solitary wave solutions are derived and it is also shown that cavity solutions are not possible

1987-01-01

14

TM Waves Propagation at Magnetoplasma-MTMs Interface  

Directory of Open Access Journals (Sweden)

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.

Rifa J. El-Khozondar

2012-11-01

15

TM Waves Propagation at Magnetoplasma-MTMs Interface  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

El-khozondar, Rifa J.; El-khozondar, Hala J.; Shabat, Mohammed M.; Koch, Alexander W.

2012-01-01

16

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

2001-03-01

17

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

Science.gov (United States)

We have conducted studies of a revolutionary new concept for conducting a Europa Sample Return Mission. Robotic spacecraft exploration of the Solar System has been severely constrained by the large energy requirements of interplanetary trajectories and the inherent delta V limitations of chemical rockets. Current missions use gravitational assists from intermediate planets to achieve these high-energy trajectories restricting payload size and increasing flight times. We propose a 6-year Europa Sample Return mission with very modest launch requirements enabled by MITEE. A new nuclear thermal propulsion engine design, termed MITEE (MIniature reacTor EnginE), has over twice the delta V capability of H2/O2 rockets (and much greater when refueled with H2 propellant from indigenous extraterrestrial resources) enabling unique missions that are not feasible with chemical propulsion. The MITEE engine is a compact, ultra-lightweight, thermal nuclear rocket that uses hydrogen as the propellant. MITEE, with its small size (50 cm O.D.), low mass (200 kg), and high specific impulse (~1000 sec), can provide a quantum leap in the capability for space science and exploration missions. The Robotic Europa Explorer (REE) spacecraft has a two-year outbound direct trajectory and lands on the satellite surface for an approximate 9 month stay. During this time, the vehicle is refueled with H2 propellant derived from Europa ice by the Autonomous Propellant Producer (APP), while collecting samples and searching for life. A small nuclear-heated submarine probe, the Autonomous Submarine Vehicle (ASV), based on MITEE technology, would melt through the ice and explore the undersea realm. The spacecraft has approximately a three year return to Earth after departure from Europa with samples onboard. Spacecraft payload is 430 kg at the start of the mission and can be launched with a single, conventional medium-sized Delta III booster. The spacecraft can bring back 25 kg of samples from Europa. Europa, in the Jovian system, is a high priority target for an outer Solar System exploration mission. More than a decade ago the Voyager spacecraft revealed Europa as a world swathed in ice and geologically young. NASA's Galileo spacecraft passed approximately 500 miles above the surface and provided detailed images of Europa's terrain marked by a dynamic topology that appeared to be remnants of ice volcanoes or geysers. The surface temperature averages a chilly -200° C. The pictures appear to show a relatively young surface of ice, possibly only 1 km thick in some places. Internal heating of Europa from Jupiter's tidal pull could form an ocean of liquid water beneath the surface. More recently, Ganymede and Callisto are believed to be ocean-bearing Jovian moons based on magnetometer measurements from the Galileo spacecraft. If liquid water exists, life may also. NASA plans to send an orbiting spacecraft to Europa to measure the thickness of the ice and to detect if an underlying liquid ocean exists. This mission would precede the proposed Europa Sample Return mission, which includes dispatching an autonomous submarine-like vehicle that could melt through the ice and explore the undersea realm. Because of the large energy requirements typical of these ambitious solar system science missions, use of chemical rockets results in interplanetary spacecraft that are prohibitive in terms of Initial Mass in Low- Earth Orbit (IMLEO) and cost. For example, using chemical rockets to return samples from Europa appears to be technically impractical, as it would require large delta V and launch vehicle capabilities. On the other hand, use of nuclear thermal rockets will significantly reduce IMLEO and, subsequently, costs. Moreover, nuclear thermal rockets can utilize extraterrestrial resources as propellants, an option not practical with chemical rockets. This "refueling" capability would enable nuclear rockets to carry out very high-energy missions, such as the return of large amounts of extraterrestrial material to Earth. The Europa missions considered in this pro

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

2002-01-01

18

Mach Cones in Space and Laboratory Dusty Magnetoplasmas  

Energy Technology Data Exchange (ETDEWEB)

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 magnetoacoustic, oscillonic Mach cones, etc.), and clearly explain how they are relevant to space and laboratory dusty magnetoplasmas.

Mamun, A.A. [Jahangirnagar Univ., Dhaka (Bangladesh). Dept. of Physics; Shukla, P.K. [Ruhr-Univ., Bochum (Germany). Inst. fuer Theoretische Physik IV

2005-04-01

19

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.

2012-01-09

20

Electron-acoustic vortices in multicomponent magnetoplasma  

International Nuclear Information System (INIS)

Linear and nonlinear properties of electron-acoustic waves in a multicomponent magnetoplasma comprising of cold and beam electrons and two species of thermal unmagnetized ions are investigated here. It is found that the electron beam velocity, electron Debye length, electron Larmor radius, and concentration of the cold and beam electrons affect the linear dispersion characteristics of electron-acoustic wave. It is also found that such a multicomponent plasma admits dipolar and vortex street type structures for the normalized electrostatic potential ?<1. The relevance of this investigation in laboratory as well as in space plasmas such as in auroral region, geomagnetic tail, etc. is also pointed out.

2010-05-01

 
 
 
 
21

Radiation pattern from a cold magnetoplasma antenna  

International Nuclear Information System (INIS)

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

2009-07-01

22

Wave fronts of radiated electromagnetic modes in a magnetoplasma waveguide  

International Nuclear Information System (INIS)

Wave fronts and ray trajectories of electromagnetic modes radiated from a local source are obtained in an inhomogeneous magnetoplasma waveguide. They are investigated numerically using a kinetic theory at frequencies below the electron cyclotron frequency

1981-01-01

23

Theory of vortex flows in partially ionized magnetoplasmas  

International Nuclear Information System (INIS)

A complete theory for vortex flows in partially ionized magnetoplasmas is presented. Accurate analytical and numerical results are obtained concerning the structure of a Burger's vortex and a tripolar vortex. A novel type of rotating tripolar vortices with elliptic cores are found in the systems dominated by the convection in incompressible flows, but whose generation is triggered by the diffusive and compressible effects. Our vortex flow models successfully explain recent observations from laboratory magnetoplasmas and geophysical flows

2004-06-07

24

Theory of vortex flows in partially ionized magnetoplasmas  

Energy Technology Data Exchange (ETDEWEB)

A complete theory for vortex flows in partially ionized magnetoplasmas is presented. Accurate analytical and numerical results are obtained concerning the structure of a Burger's vortex and a tripolar vortex. A novel type of rotating tripolar vortices with elliptic cores are found in the systems dominated by the convection in incompressible flows, but whose generation is triggered by the diffusive and compressible effects. Our vortex flow models successfully explain recent observations from laboratory magnetoplasmas and geophysical flows.

Jovanovic, D.; Shukla, P.K

2004-06-07

25

Electron acoustic soliton in a quantum magnetoplasma  

International Nuclear Information System (INIS)

A theoretical investigation is carried out for the first time to understand the linear and nonlinear properties of obliquely propagating electron-acoustic solitary waves (EASWs) in a two-electron population quantum magnetoplasma. A dispersion relation in the linear regime and the Zakharov-Kuznetsov (ZK) equation in the nonlinear regime are derived by using a quantum hydrodynamic set of equations. It is observed that the magnetic field contributes in the wave dispersion through the weakly transverse direction in the ZK equation. It is also found that propagation characteristics of the EASW are significantly affected by the presence of quantum corrections and the ratio of hot to cold electron concentration. The results presented in this study may be helpful to understand the salient features of the finite-amplitude localized electron acoustic solitary pulses in a two-population electron Fermi gas observed in laser-produced plasmas

2008-02-01

26

Wave propagation in an inhomogeneous relativistic magnetoplasma  

International Nuclear Information System (INIS)

This paper contains two subjects. In the first part a self-consistent description is given of the electron and ion statics in a relativistic inhomogeneous magnetoplasma. This problem is treated for a non-relativistic plasma with electrons and ions having equal charge. Furthermore it is shown that there exist equilibrium solutions that simulate the interface of a semi-infinite neutral plasma with a magnetic field. In the second part the time-dependent Vlasov-Maxwell system is linearized around this equilibrium. The case of a non-relativistic plasma was treated by Martin. In the present paper a set of fully relativistic differential equations is derived for the first order electric field. (author) 5 refs

1991-01-01

27

Wave propagation in an inhomogeneous relativistic magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

This paper contains two subjects. In the first part a self-consistent description is given of the electron and ion statics in a relativistic inhomogeneous magnetoplasma. This problem is treated for a non-relativistic plasma with electrons and ions having equal charge. Furthermore it is shown that there exist equilibrium solutions that simulate the interface of a semi-infinite neutral plasma with a magnetic field. In the second part the time-dependent Vlasov-Maxwell system is linearized around this equilibrium. The case of a non-relativistic plasma was treated by Martin. In the present paper a set of fully relativistic differential equations is derived for the first order electric field. (author) 5 refs.

Kerkehof, M.J.; Kamp, L.P.J.; Sluijter, F.W. (Technische Univ. Eindhoven (Netherlands)); Weenink, M.P.H. (Technische Hogeschool Eindhoven (Netherlands). Afdeling der Elektrotechniek)

1991-01-01

28

Potential coherent structures in nonuniform streaming dusty magnetoplasma  

International Nuclear Information System (INIS)

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

2000-12-05

29

Potential coherent structures in nonuniform streaming dusty magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

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

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

2001-07-01

30

Impulsiveness in professional fighters.  

Science.gov (United States)

Sports involving repeated head trauma are associated with risk of neurodegenerative disorders such as chronic traumatic encephalopathy (CTE). Among the behavioral manifestations of CTE is increased impulsiveness. Here, the authors investigate the relationship between impulsiveness and exposure to head trauma in a large group of active professional fighters. Fighters tended to report less impulsiveness than did non-fighting control respondents. Overall, greater fight exposure was associated with higher levels of a specific form of impulsiveness, although there were differences between mixed martial arts fighters and boxers. Fight exposure was associated with reduction in volume of certain brain structures, and these changes were also associated with impulsiveness patterns. Longitudinal studies of professional fighters are important to understand the risk for neuropsychiatric problems. PMID:24515676

Banks, Sarah J; Mayer, Brittany; Obuchowski, Nancy; Shin, Wanyong; Lowe, Mark; Phillips, Michael; Modic, Michael; Bernick, Charles

2014-01-01

31

Impulse Response Function  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Impulse response functions are useful for studying the interactions between variables in a vector autoregressive model. They represent the reactions of the variables to shocks hitting the system. It is often not clear, however, which shocks are relevant for studying specific economic problems. Therefore structural information has to be used to specify meaningful shocks. Structural vector autoregressive models and the estimation of impulse responses are discussed and extensions to models with ...

Luetkepohl, Helmut

2008-01-01

32

Parallel and perpendicular velocity sheared flows driven tripolar vortices in an inhomogeneous electron-ion quantum magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

Nonlinear equations governing the dynamics of finite amplitude drift-ion acoustic-waves are derived by taking into account sheared ion flows parallel and perpendicular to the ambient magnetic field in a quantum magnetoplasma comprised of electrons and ions. It is shown that stationary solution of the nonlinear equations can be represented in the form of a tripolar vortex for specific profiles of the equilibrium sheared flows. The tripolar vortices are, however, observed to form on very short scales in dense quantum plasmas. The relevance of the present investigation with regard to dense astrophysical environments is also pointed out.

Mirza, Arshad M. [Theoretical Plasma Physics Group, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Masood, W. [TPPD, PINSTECH, P.O. Nilore, Islamabad (Pakistan) and National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan)

2011-12-15

33

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

International Nuclear Information System (INIS)

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

1988-07-01

34

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)

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.

Lindberg Nina

2007-07-01

35

Oblique propagation of nonlinear electrostatic waves in dense astrophysical magnetoplasmas  

Energy Technology Data Exchange (ETDEWEB)

Nonlinear quantum ion-acoustic waves in dense dissipative as well as non-dissipative magnetized plasmas are investigated employing the quantum hydrodynamic model. In this regard, Zakharov Kuznetsov Burgers equation is derived in quantum plasmas, for the first time, using the small amplitude perturbation expansion method. The unique features of nonlinear electrostatic structures in pure electron-ion quantum magnetoplasma are highlighted and the parametric domain of the applicability of the model is unequivocally expressed. The present study may be useful to understand the nonlinear propagation characteristics of electrostatic shock and solitary structures in dense astrophysical systems where the quantum effects are expected to dominate.

Masood, W.; Siddiq, M. [Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad 54000 (Pakistan); National Centre for Physics (NCP), Shahdara Valley Road, 44000, Islamabad (Pakistan); Rizvi, H. [Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad 54000 (Pakistan)

2011-10-15

36

Explosive and solitary excitations in a very dense magnetoplasma  

International Nuclear Information System (INIS)

A two-component dense magnetoplasma consisting of ions and degenerate electrons is considered. The basic set of hydrodynamic and Poisson equations are reduced to the Zakharov-Kuznetsov (ZK) equation by using the reductive perturbation technique. The basic features of the electrostatic excitations are investigated by applying a new direct method to the ZK equation. It is found that the latter has new solutions, which admit the propagation of either solitary or explosive pulses. The relevance of the new direct method to other nonlinear partial differential equations is also discussed

2008-08-25

37

Zonal winds and dipolar vortices in a rotating dusty magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

It is shown that the Rossby and dust-Alfven waves in a rotating dusty magnetoplasma are coupled due to the spatial nonuniformity of the angular rotation velocity of the dust fluid. The nonlinear wave interaction is governed by a pair of equations comprising the evolution of the dust fluid vorticity and the dust-Alfven wave magnetic field. These nonlinear equations are then used to investigate the generation of zonal winds and the formation of a dipolar vortex. The results are relevant for understanding the origin of the strong turbulence and large scale structures, which are often observed in the planetary magnetospheres.

Shukla, P K [Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Dwivedi, P K [Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Stenflo, L [Department of Plasma Physics, Umeaa University, SE-90187 Umeaa (Sweden)

2003-03-01

38

Faraday tarotion: new parameter for electromagnetic pulse propagation in magnetoplasma  

International Nuclear Information System (INIS)

Extreme distortion and time-dependent Faraday rotation occur for propagation of short electromagnetic pulses in magnetoplasma, for some ranges of plasma parameters. In order to relate pulse and monochromatic waves for propagation-path diagnostic purposes, a new parameter is introduced for the transmitted pulse train which has properties that correspond very accurately to results that would be expected for Faraday rotation of a continuous wave having the central frequency of the incident pulse spectrum. Results for 5-ns pulses (10 GHz) are presented for varying propagating length, static magnetic field, electron density, and collisional absorption

1976-01-01

39

Faraday tarotion: new parameter for electromagnetic pulse propagation in magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

Extreme distortion and time-dependent Faraday rotation occur for propagation of short electromagnetic pulses in magnetoplasma, for some ranges of plasma parameters. In order to relate pulse and monochromatic waves for propagation-path diagnostic purposes, a new parameter is introduced for the transmitted pulse train which has properties that correspond very accurately to results that would be expected for Faraday rotation of a continuous wave having the central frequency of the incident pulse spectrum. Results for 5-ns pulses (10 GHz) are presented for varying propagating length, static magnetic field, electron density, and collisional absorption.

Bloch, S.C.; Lyons, P.W.

40

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

Energy Technology Data Exchange (ETDEWEB)

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.

Garkusha, I. E.; Tereshin, V. I.; Chebotarev, V. V.; Solyakov, D. G.; Petrov, Yu. V.; Ladygina, M. S.; Marchenko, A. K.; Staltsov, V. V.; Yelisyeyev, D. V. [National Academy of Sciences of Ukraine, Institute of Plasma Physics, National Science Center ' Kharkiv Institute of Physics and Technology,' (Ukraine)

2011-11-15

 
 
 
 
41

Buying impulses : a study on impulsive consumption  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This dissertation's objectives were to validate impulse buying tendency as a genuinely distinctive construct related to impulse purchase behavior and attached to fundamental personality traits, and its relationships to a number of relevant factors. Studies reported were steps to a better understanding of the impulse buying phenomenon. In the first 2 studies (using Dutch and Indonesian samples), a reliable 20-item scale to measure impulse buying tendency was developed. The scale has 2 facets r...

2003-01-01

42

Temperature effects on the beat heating of a collisional magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

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.

Arora, B.B. (State Forensic Science Lab., Rajasthan, Jaipur (India)); Phalswal, D.R.; Varma, N.L. (Rajasthan Univ., Jaipur (India). Dept. of Physics)

1983-01-01

43

Evolution of magnetic topology of an erupting arched laboratory magnetoplasma  

Science.gov (United States)

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)

Tripathi, S.; Gekelman, W. N.

2013-12-01

44

Sheath structure of a probe in a flowing magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

Distributions of plasma and fields near an electric probe in a flowing magnetoplasma are studied by means of 3-D numerical simulations. The flowing plasma represents the relative motion of the probe with respect to the plasma, as imposed by the orbital motion in space. The field distribution shows wings of a resonance-cone like structure, analogous to the whistler wings created by a moving electrode in a laboratory plasma. In addition to the wings, the relative motion also creates a ``bow shock`` in front of a positive probe along with the usual wake with negative potentials in its back. The relative motion significantly enhances the current collection by the positive probe over the upper-bound current given by the conservation of the canonical angular momentum in a stationary plasma.

Singh, N.; Bashi, B.I.; Leung, W.C. [Univ. of Alabama, Huntsville, AL (United States). Dept. of Electrical and Computer Engineering

1995-12-31

45

Amplitude modulated drift wave packets in a nonuniform magnetoplasma  

CERN Document Server

We consider the amplitude modulation of low-frequency, long wavelength electrostatic drift wave packets in a nonuniform magnetoplasma with the effects of equilibrium density, electron temperature and magnetic field inhomogeneities. The dynamics of the modulated drift wave packet is governed by a nonlinear Schr\\"odinger equation. The latter is used to study the modulational instability of a Stoke's wave train to a small longitudinal perturbation. It is shown that the drift wave packet is stable (unstable) against the modulation when the drift wave number lies in $0< k < 1/\\sqrt{2}$ $(1/\\sqrt{2}

Shukla, P K; 10.1016/j.physleta.2012.07.008

2012-01-01

46

Relativistic impulse approximation  

International Nuclear Information System (INIS)

During the past year has been used the relativistic impulse approximation (RIA)-Dirac equation model to describe intermediate energy proton-nucleus scattering. Specifically the energy and mass dependence characteristics of the model have been examined in detail. Improvements in the kinematics and investigation of the model sensitivity to the overall matter densities and to the lower components of the target nucleus wave function have been carried out. After giving a brief introduction to the subject the authors discuss the RIA-Dirac equation model is discussed and new results shown

1984-11-01

47

Anatomy of a SAR impulse response.  

Energy Technology Data Exchange (ETDEWEB)

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.

Doerry, Armin Walter

2007-08-01

48

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.

2012-02-27

49

Generation of zonal magnetic fields by drift waves in a current carrying nonuniform magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

It is shown that zonal magnetic fields (ZMFs) can be nonlinearly excited by incoherent drift waves (DWs) in a current carrying nonuniform magnetoplasma. The dynamics of incoherent DWs in the presence of ZMFs is governed by a wave-kinetic equation. The governing equation for ZMFs in the presence of nonlinear advection force of the DWs is obtained from the parallel component of the electron momentum equation and the Faraday law. Standard techniques are used to derive a nonlinear dispersion relation, which depicts instability via which ZMFs are excited in plasmas. ZMFs may inhibit the turbulent cross-field particle and energy transport in a nonuniform magnetoplasma.

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

2010-05-17

50

Self-gravitation effect on the nonlinear dynamics of an electron positron ion magnetoplasma  

Science.gov (United States)

A new set of nonlinear equations governing the dynamics of low-frequency electrostatic drift waves in a self-gravitating electron positron ion (e p i) magnetoplasma with equilibrium density, temperature, magnetic field and velocity gradients has been derived. It is shown that possible stationary solutions of the nonlinear equations can be represented in the form of dipolar and tripolar vortices of gravitational potential. The results of the present investigation are useful to understand the nonlinear dynamics of low-frequency gravitational-drift waves in laboratory and astrophysical e p i magnetoplasmas.

Azeem, M.; Mirza, Arshad M.

2006-01-01

51

Laser pulse propagation in inhomogeneous magnetoplasma channels and wakefield acceleration  

Science.gov (United States)

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

Sharma, B. S.; Jain, Archana; Jaiman, N. K.; Gupta, D. N.; Jang, D. G.; Suk, H.; Kulagin, V. V.

2014-02-01

52

Behavioral components of impulsivity.  

Science.gov (United States)

Acting in accord with long-term goals requires control of interfering impulses, the success of which depends on several different processes. Using a structural-equation modeling approach, we investigated 5 behavioral components of impulsivity: the control of stimulus interference, proactive interference, and response interference, as well as decisional and motivational impulsivity. Results support the existence of 5 correlated but separable components of impulsive behavior. The present study is the 1st to demonstrate the separability of stimulus and response interference. It also supports the notion that control of response-related interference is not a unitary construct: Response-selection demands were separable from those of withholding or stopping. Relations between behavioral impulsivity components and self-report measures of impulsivity were largely absent. We conclude that as the construct of impulsivity has been extended to describe an increasingly diverse set of phenomena and processes, it has become too broad to be helpful in guiding future research. PMID:23957282

Stahl, Christoph; Voss, Andreas; Schmitz, Florian; Nuszbaum, Mandy; Tüscher, Oliver; Lieb, Klaus; Klauer, Karl Christoph

2014-04-01

53

Algorithms for pharmacological treatment of personality dimensions: symptom-specific treatments for cognitive-perceptual, affective, and impulsive-behavioral dysregulation.  

Science.gov (United States)

A pharmacological approach to treating patients with personality disorders (PD) is based on evidence that some dimensions of personality are mediated by variations in neurotransmitter physiology and are responsive to medication effects. Target symptoms for pharmacotherapy in the PD patient are derived from expressions of cognitive-perceptual, affective, and impulsive-behavioral dysregulation of central neurotransmitter functions. Pharmacotherapy is directed at state symptoms during periods of acute decompensation and at trait vulnerabilities, which represent the diathesis to future episodes. A basic assumption of this approach is that neurotransmitter biology transcends Axis I and Axis II definitions and that closely related symptoms may share a common pathophysiology, independent of categorical definition. A common pathophysiology implies the possibility of shared responsiveness to medication. Using a dimensional definition of symptom domains, the author has developed treatment algorithms for cognitive-perceptual symptoms, affective dysregulation, and impulsive-behavioral dyscontrol in personality disorder patients. PMID:9604516

Soloff, P H

1998-01-01

54

Characteristics of slow magnetoplasma waves on the surface of a semiconductor  

Energy Technology Data Exchange (ETDEWEB)

It is demonstrated that it is possible to excite resonantly and detect magnetoplasma waves on the surface of a semiconductor; and the results of an investigation of the propagation of such waves at various angles relative to a magnetic field B are reported. (AIP)

Ruibis, G.; Tolutis, R.

1982-07-01

55

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.

2010-01-11

56

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  

Science.gov (United States)

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.

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

2013-06-01

57

Optical properties of impulsive flares  

Energy Technology Data Exchange (ETDEWEB)

The optical and morphological properties of impulsive flares are examined, showing that all impulsive flares occur close to sunspots and on magnetic inversion lines with steep gradients. Impulsive flares are defined and flare brightness variations and the magnetic structure of flares are discussed. The basic characteristics of impulsive flares are described and the evolution of a typical impulsive flare is outlined. 17 refs.

Zirin, H.; Tang, F.

1990-06-01

58

Model-free impulse responses  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper introduces methods for computing impulse response functions that do not require specification and estimation of the unknown dynamic multivariate system itself. The central idea behind these methods is to estimate flexible local projections at each period of interest rather than extrapolating into increasingly distant horizons from a given model, as it is usually done in vector autoregressions (VAR). The advantages of local projections are numerous: (1) they can be estimated by simp...

Jorda?, O?scar

2004-01-01

59

Model-Free Impulse Responses  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper introduces methods for computing impulse response functions that do not require specification and estimation of the unknown dynamic multivariate system itself. The central idea behind these methods is to estimate flexible local projections at each period of interest rather than extrapolating into increasingly distant horizons from a given model, as it is usually done in vector autoregressions (VAR). The advantages of local projections are numerous: (1) they can be estimated by simp...

Jorda?, O?scar

2003-01-01

60

A Neurogenetic Approach to Impulsivity  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Impulsivity is a complex and multidimensional trait that is of interest to both personality psychologists and to clinicians. For investigators seeking the biological basis of personality traits, the use of neuroimaging techniques such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) revolutionized personality psychology in less than a decade. Now, another revolution is under way, and it originates from molecular biology. Specifically, new findings in mole...

Congdon, Eliza; Canli, Turhan

2008-01-01

 
 
 
 
61

Impulsivity and Its Treatment  

Directory of Open Access Journals (Sweden)

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.

P?nar Güzel Özdemir

2012-09-01

62

Impulsivity and Academic Cheating  

Science.gov (United States)

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

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

2009-01-01

63

Impulse generation by detonation tubes  

Science.gov (United States)

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

Cooper, Marcia Ann

64

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

Science.gov (United States)

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 (i.e., delay discounting, probability discounting, and the Balloon Analogue Risk Task), impulsive action (i.e., the stop signal task, the go/no-go task, and commission errors on the continuous performance task), and inattention (i.e., attention lapses on a simple reaction time task and omission errors on the continuous performance task). Healthy adults (n = 128) performed the battery on two separate occasions. Reliability estimates for the individual tasks ranged from moderate to high, with Pearson correlations within the specific impulsivity domains as follows: impulsive choice (r range: .76-.89, ps Profile of Mood States, was assessed in relation to variability in performance on each of the behavioral tasks. Change in performance on the delay discounting task was significantly associated with change in positive mood and arousal. No other behavioral measures were significantly associated with mood. In sum, the current analysis demonstrates that behavioral measures of impulsivity are reliable measures and thus can be confidently used to assess various facets of impulsivity as intermediate phenotypes for drug abuse. PMID:24099351

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

2013-12-01

65

Modulation of drift-wave envelopes in a nonuniform quantum magnetoplasma  

International Nuclear Information System (INIS)

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

2014-04-01

66

Modulation of drift-wave envelopes in a nonuniform quantum magnetoplasma  

Science.gov (United States)

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.

Misra, A. P.

2014-04-01

67

Modulation of drift-wave envelopes in a nonuniform quantum magnetoplasma  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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) equ...

Misra, A. P.

2014-01-01

68

Langmuir Shock Pulses in a Rotating Electron-Positron-Ion Magnetoplasma  

International Nuclear Information System (INIS)

A theoretical investigation has been made for nonlinear Langmuir structures (Langmuir shock waves) in a rotating electron-positron-ion magnetoplasma with stationary positive ions. For this purpose, the reductive perturbation technique is employed to the hydrodynamical electrons/positrons fluid equations and Poisson equation, obtaining extended Zakharov-Kuznetsov (EZK) equation. The latter has been solved analytically and the features of the nonlinear excitations are investigated numerically. Furthermore, the propagation condition for the nonlinear structures is examined.

2010-12-14

69

Angular momentum transport produced by shear flow driven drift waves in a collisional magnetoplasma  

International Nuclear Information System (INIS)

A shear flow instability in a nonuniform partially ionized magnetoplasma has been investigated and the angular momentum transport of charged particles caused by drift waves has been estimated. The angular momentum transport of the electrons and ions is not equal because the system is not conservative. The present investigation should help to understand the origin of fluctuations and associated parallel momentum transport of charged particles in nonuniform laboratory and astrophysical plasmas with sheared ion flow

2008-10-27

70

Optically measured explosive impulse  

Science.gov (United States)

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

Biss, Matthew M.; McNesby, Kevin L.

2014-06-01

71

Ballistic impulse gauge  

Science.gov (United States)

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

Ault, Stanley K. (Antioch, CA)

1993-01-01

72

A calculable impulse voltage calibrator  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis describes the principle, design, construction, and uncertainty analysis of a calculable impulse voltage calibrator. The calibrator can be used as a primary reference for impulse voltage measurements. The calibrator generates lightning impulses (LI) with known peak value (UP), front time (T1), and time to half value (T2); or switching impulses (SI) with known peak value (UP), time to peak (TP), and time to half value (T2). The peak voltages of the constructed devices range from 50?...

Ha?llstro?m, Jari

2002-01-01

73

Impulse radar studfinder  

Energy Technology Data Exchange (ETDEWEB)

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.

McEwan, Thomas E. (Livermore, CA)

1995-01-01

74

Relativistic impulse dynamics  

Science.gov (United States)

Classical electrodynamics has some annoying rough edges. The self-energy of charges is infinite without a cutoff. The calculation of relativistic trajectories is difficult because of retardation and an average radiation reaction term. By reconceptuallizing electrodynamics in terms of exchanges of impulses rather than describing it by forces and potentials, we eliminate these problems. A fully relativistic theory using photonlike null impulses is developed. Numerical calculations for a two-body, one-impulse-in-transit model are discussed. A simple relationship between center-of-mass scattering angle and angular momentum was found. It reproduces the Rutherford cross section at low velocities and agrees with the leading term of relativistic distinguishable-particle quantum cross sections (Møller, Mott) when the distance of closest approach is larger than the Compton wavelength of the particle. Magnetism emerges as a consequence of viewing retarded and advanced interactions from the vantage point of an instantaneous radius vector. Radiation reaction becomes the local conservation of energy-momentum between the radiating particle and the emitted impulse. A net action is defined that could be used in developing quantum dynamics without potentials. A reinterpretation of Newton’s laws extends them to relativistic motion.

Swanson, Stanley M.

2011-08-01

75

Relativistic impulse dynamics.  

Science.gov (United States)

Classical electrodynamics has some annoying rough edges. The self-energy of charges is infinite without a cutoff. The calculation of relativistic trajectories is difficult because of retardation and an average radiation reaction term. By reconceptuallizing electrodynamics in terms of exchanges of impulses rather than describing it by forces and potentials, we eliminate these problems. A fully relativistic theory using photonlike null impulses is developed. Numerical calculations for a two-body, one-impulse-in-transit model are discussed. A simple relationship between center-of-mass scattering angle and angular momentum was found. It reproduces the Rutherford cross section at low velocities and agrees with the leading term of relativistic distinguishable-particle quantum cross sections (Møller, Mott) when the distance of closest approach is larger than the Compton wavelength of the particle. Magnetism emerges as a consequence of viewing retarded and advanced interactions from the vantage point of an instantaneous radius vector. Radiation reaction becomes the local conservation of energy-momentum between the radiating particle and the emitted impulse. A net action is defined that could be used in developing quantum dynamics without potentials. A reinterpretation of Newton's laws extends them to relativistic motion. PMID:21929132

Swanson, Stanley M

2011-08-01

76

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

Energy Technology Data Exchange (ETDEWEB)

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.

Choudhury, B.; Goswami, R.; Bora, M. P. [Department of Physics, Gauhati University, Guwahati 781014 (India); Das, G. C. [Material Science Division, Institute of Advanced Studies in Science and Technology, Guwahati 781035 (India)

2013-04-15

77

Vortical structures in a nonuniform pair-ion dust magnetoplasma with sheared flows  

International Nuclear Information System (INIS)

It has been shown that sheared pair-ion flows can generate low frequency electrostatic waves in a nonuniform dust pair-ion magnetoplasma. Linear analysis shows that the electrostatic driftlike waves can become unstable due to shear flow. The conditions of modes instability are given. These excited modes gain large amplitudes and start interacting among themselves. The interaction is governed by the nonlinear equations containing the vector nonlinearities. Stationary solutions of the nonlinear mode coupling equations can be represented in the form of a vortex chain and a dipolar vortex. The relevance of the work to laboratory plasmas are pointed out.

2010-01-01

78

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

International Nuclear Information System (INIS)

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

2013-09-01

79

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

Energy Technology Data Exchange (ETDEWEB)

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.

Garkusha, I. E.; Chebotarev, V. V.; Solyakov, D. G.; Petrov, Yu. V.; Ladygina, M. S.; Marchenko, A. K.; Staltsov, V. V.; Yelisyeyev, D. V. [National Academy of Sciences of Ukraine, Institute of Plasma Physics, National Science Center ' Kharkiv Institute of Physics and Technology,' (Ukraine)

2012-02-15

80

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

Energy Technology Data Exchange (ETDEWEB)

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

Ata-ur-Rahman,; Qamar, A. [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan); National Centre for Physics, QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Masood, W. [National Centre for Physics, QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); COMSATS, Institute of Information Technology, Park Road, Chak Shahzad, Islamabad 44000 (Pakistan); Eliasson, B. [Physics Department, University of Strathclyde, Glasgow G4 0NG, Scotland (United Kingdom)

2013-09-15

 
 
 
 
81

Measuring impulsivity in daily life: the momentary impulsivity scale.  

Science.gov (United States)

Impulsivity is a core feature of many psychiatric disorders. Traditionally, impulsivity has been assessed using retrospective questionnaires or laboratory tasks. Both approaches neglect intraindividual variability in impulsivity and do not capture impulsivity as it occurs in real-world settings. The goal of the current study was to provide a method for assessing impulsivity in daily life that provides both between-individual and within-individual information. Participants with borderline personality disorder (BPD; n = 67) or a depressive disorder (DD; n = 38) carried an electronic diary for 28 days and responded to 9 impulsivity items up to 6 times per day. Item distributions and iterative exploratory factor analysis (EFA) results were examined to select the items that best captured momentary impulsivity. A brief 4-item scale was created that can be used for the assessment of momentary impulsivity. Model fit was good for both within- and between-individual EFA. As expected, the BPD group showed significantly higher scores on our Momentary Impulsivity Scale than the DD group, and the resulting scale was moderately correlated with common trait impulsivity scales. PMID:24274047

Tomko, Rachel L; Solhan, Marika B; Carpenter, Ryan W; Brown, Whitney C; Jahng, Seungmin; Wood, Phillip K; Trull, Timothy J

2014-06-01

82

Modulation of drift-wave envelopes in a nonuniform quantum magnetoplasma  

CERN Document Server

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.

Misra, A P

2014-01-01

83

Role of ambient magnetic field in driving the eruption of an arched laboratory magnetoplasma  

Science.gov (United States)

Eruptions of arched magnetoplasma structures cover a wide spatiotemporal scale on the Sun and drive energetic phenomena such as coronal mass ejections. Due to presence of an electrical-current and associated twist in the magnetic-field, the term “arched magnetic flux rope” (AMFR) is used for these structures. Contemporary models of solar eruptions predict that solar AMFRs are confined for relatively long duration (days to weeks) by ambient magnetic fields (known as strapping field) before their sudden eruption. The structure of the ambient-magnetic-field plays an important role in the evolution of the confined and erupting solar AMFRs. In a laboratory plasma experiment, the interaction between an AMFR and its ambient magnetic field has been investigated. The AMFR (plasma ? ? 10-3, Lundquist number ?102-105, AMFR radius/ion-gyroradius ? 20, B ? 1000 G at footpoints) was produced using a LaB6 plasma source in an ambient magnetoplasma (B ? 0 - 100 G). The ambient magnetic field was oriented normal to the symmetry plane of the AMFR. The experiment runs continuously and generates reproducible AMFR eruptions with a period of 2 s. Hence, the plasma parameters were recorded with a good resolution (spatial-resolution/AMFR-length ? 10-2 - 10-3, temporal-resolution/eruption-time ? 10-3) using computer-controlled movable probes. A fast-CCD camera was utilized to capture the evolution of the AMFR. The pre-eruption phase of the AMFR remained quiescent for ? 100 Alfven transit times and the camera images evinced its persistent appearance. In contrast, the post-eruption phase of the AMFR was observed to be associated with significant changes in its magnetic topology. Our initial results suggest that linkage of the magnetic-field of the AMFR with the ambient magnetoplasma (which is ignored in the models of solar eruptions) plays the most important role in the ejection of a large flux rope from the leading edge of the AMFR. Implications of these results to actual solar eruptions will 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 the Basic Plasma Science Facility, UCLA and supported by US DOE and NSF)

Tripathi, Shreekrishna; Gekelman, Walter

2014-06-01

84

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

Science.gov (United States)

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

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

2014-03-01

85

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

Energy Technology Data Exchange (ETDEWEB)

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.

Petrosky, L.J.; Disney, R.K.; Mangus, J.D. (Advanced Programs Department, Westinghouse Electric Corporation, P.O. Box 158, Madison, Pennsylvania 15663-0158 (United States)); Gunn, S.A.; Zweig, H.R. (Rocketdyne Division, Rockwell International Corporation, 6633 Canoga Avenue, P.O. Box 7922, Canoga Park, California 91309-7922 (United States))

1993-01-10

86

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

1993-01-10

87

Reciprocity relations between currents and fields in plane-stratified magnetoplasmas  

International Nuclear Information System (INIS)

The dyadic Green's function, relating currents and fields in transverse=K space, is determined for a homogenous magnetoplasma, and then extended to a plane-stratified system by means of the reflexion and transmission matrices of the medium, taking into account multiple reflexions at the source and observation points. A conjugate problem is next considered, in which the propagation eigenvectors have a certain mirror symmetry with respect to those in the original problem and, by relating the scattering matrices in the two cases, a Lorentz-type reciprocity theorem is derived relating currents and fields in the original problem with the mirrored currents and their associated wave fields which characterize the conjugate problem. (author)

1981-01-01

88

Spectral characteristics of low-frequency turbulence in toroidal collisional magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

The dispersion and spectral characteristics of low-frequency fluctuations excited in collisional toroidal magnetoplasma is reported. The plasma produced under the operating conditions have magnetized electrons, unmagnetized ions, [bold E][parallel][del][ital n][perpendicular][bold B] and [del][ital n] antiparallel to effective gravity [bold g]. The low frequency ([lt]ion-gyrofrequency) electrostatic fluctuations observed in density and potential are turbulent, travel mainly in azimuthal direction and are excited by the cross-field instability. The spectral indices of the [ital k] spectra for the density and potential fluctuations, as computed using pair probe technique, are [minus]3.8[plus minus]0.5 and [minus]6.0[plus minus]0.6, respectively. These results are in good agreement with the [ital in] [ital situ] measurements of fluctuations in equatorial electrojet and the earlier laboratory experiments on the cross-field instability. Numerical simulations and nonlinear theories, however, predict flatter spectra.

Prasad, G.; Bora, D.; Saxena, Y.C. (Institute for Plasma Research, Bhat, Gandhinagar 382 424 (India))

1994-08-01

89

Spin effect on parametric decay of oblique Langmuir wave in degenerate magneto-plasmas  

Energy Technology Data Exchange (ETDEWEB)

The electron spin ?1/2 effects on the parametric decay instability of oblique Langmuir wave into low-frequency electromagnetic shear Alfven wave and Left-Handed Circularly Polarized wave (LHCP) has been investigated in detail, in an electron-ion quantum plasma immersed in the uniform external magnetic field. Incorporating the quantum effects due to electron spin, Fermi pressure and Bohm potential term, the quantum magneto-hydrodynamic (QMHD) model has been used to investigate the linear and nonlinear response of the plasma species for three-wave coupling interaction in a quantum magneto-plasmas. Nonlinear dispersion relations and growth rate of the problem have been derived analytically. It has been shown that the spin of electrons has considerable effect on the growth rate of parametric instability problem even when the external magnetic field B{sub 0} is below the quantum critical magnetic field strength B{sub Q}=4.4138×10{sup 13}G.

Shahid, M. [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)

2013-08-15

90

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.

2011-01-01

91

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

Energy Technology Data Exchange (ETDEWEB)

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

Masood, W. [Theoretical Plasma Physics Division, P. O. Nilore, Islamabad (Pakistan); National Center for Physics (NCP), Islamabad 44000 (Pakistan); Rizvi, H. [Theoretical Plasma Physics Division, P. O. Nilore, Islamabad (Pakistan); Imtiaz, N. [Department of Physics, University of Alberta, Edmonton, AB, T6G 2R3 (Canada)

2012-01-15

92

Highly nonlinear ion-acoustic solitons in a warm magnetoplasma with drifting effect of electrons  

International Nuclear Information System (INIS)

Ion-acoustic solitary waves in a warm, magnetoplasma under the initial drift motion of the electrons in the direction of the magnetic field, have been investigated. It has been established that both compressive and rarefactive solitons exist within the parametric domains. For higher (lower) values of the electron drift velocity v_e"', it is demonstrated that the solitary wave is always subsonic (supersonic) near the lower regime of ? (=T_i/T_e, the ion to electron temperature ratio) and upper regime of ?, respectively. It is of paramount importance to report that a higher and constant amplitude soliton region corresponding to low ion temperature and Mach number M exists for the upper ranged values of v_e"' but to the contrary a smaller and constant amplitude soliton region exists corresponding to high ion temperature for the lower ranged values of v_e"'

1994-07-01

93

Spin effect on parametric decay of oblique Langmuir wave in degenerate magneto-plasmas  

Science.gov (United States)

The electron spin -1/2 effects on the parametric decay instability of oblique Langmuir wave into low-frequency electromagnetic shear Alfven wave and Left-Handed Circularly Polarized wave (LHCP) has been investigated in detail, in an electron-ion quantum plasma immersed in the uniform external magnetic field. Incorporating the quantum effects due to electron spin, Fermi pressure and Bohm potential term, the quantum magneto-hydrodynamic (QMHD) model has been used to investigate the linear and nonlinear response of the plasma species for three-wave coupling interaction in a quantum magneto-plasmas. Nonlinear dispersion relations and growth rate of the problem have been derived analytically. It has been shown that the spin of electrons has considerable effect on the growth rate of parametric instability problem even when the external magnetic field B0 is below the quantum critical magnetic field strength BQ=4.4138×1013G.

Shahid, M.; Murtaza, G.

2013-08-01

94

Portable High Voltage Impulse Generator  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a portable high voltage impulse generator which was designed and built with insulation up to 20 kV. This design was based on previous work in which simulation software for standard waves was developed. Commercial components and low-cost components were used in this work; however, these particular elements are not generally used for high voltage applications. The impulse generators used in industry and laboratories are usually expensive; they are built to withstand extra high voltage and they are big, making them impossible to transport. The proposed generator is portable, thereby allowing tests to be made on devices that cannot be moved from their location. The results obtained with the proposed impulse generator were satisfactory in terms of time and waveforms compared to other commercial impulse generators and the standard impulse wave simulator.

S. Gómez

2011-07-01

95

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

96

Distinctive features of ion-acoustic solitons in electron-positron-ion superdense magnetoplasmas with degenerate electrons and positrons  

International Nuclear Information System (INIS)

Using the extended Poincare-Lighthill-Kuo reductive perturbation method to study the small-amplitude ion acoustic solitary wave dynamics (propagation and interaction), it is shown that in the Thomas-Fermi magnetoplasma consisting of inertial-less degenerate electrons and positrons and isothermal ions, distinctive features emerge when the ultrarelativistic degeneracy pressure applies to electrons and positrons. Calculations show that ion-acoustic solitary waves may interact differently in such plasmas under ultrarelativistic degeneracy pressure.

2010-09-01

97

[Kleptomania: an irresistible impulse].  

Science.gov (United States)

This review presents the historical-epidemiological and clinical aspects of Kleptomania. The diagnostic criteria, on the basis of which it is categorized in the group of Impulse Control Disorders, are defined precisely. All the aspects of its causative pathogenesis are deeply analyzed, as they are projected through its phenomenological, psychoanalytical and psycho-biological approach. Particular emphasis is given on its differential diagnosis from other psycho-pathological conditions and especially from the co-morbidities that often accompany it. The frame of treatment is established and its course and the final outcome are analyzed. Finally, it is determined what should be the objectives of future research, which will contribute decisively to the ascertainment of the exact incidence of Kleptomania in the general population, to the clarification of its causative pathogenesis and especially to the most effective treatment of this serious mental disorder. PMID:21688525

Hatzigeorgiou, K

2011-01-01

98

The relativistic impulse approximation  

International Nuclear Information System (INIS)

The scattering of medium-energy nucleons from nuclei can provide information about both nuclear structure and the nucleon-nucleon (NN) interaction. Since the NN interaction has complex spin, isospin, momentum, and density dependence, nucleon-nucleus scattering exhibits a variety of phenomena. As a starting point for describing these phenomena, we use the impulse approximation, which assumes that the interaction between the projectile and target nucleons has essentially the same form as the interaction between two nucleons in free space. This approximation also implies that the scattering is dominated by single-collision processes, so it is most appropriate for scattering at medium energies and small scattering angles. Nuclear structure and the NN interaction have been studied for many years within the context of the nonrelativistic Schroedinger equation. There is a growing body of evidence, however, that the NN interaction contains large Lorentz scalar and four-vector components. To maintain the distinction between these components, it is necessary to use the Dirac equation. Thus we will describe the motion of the projectile in the field of the nucleus with the Dirac equation, and to be consistent, we also compute the target structure in terms of Dirac nucleons. The basic ingradients contained in the codes that follow are the groundstate nuclear wave function, computed in the Dirac-Hartree approximation , and the Dirac optical potential for the projectile, computed in the so-called relativistic impulse approximation (RIA). The target nucleons interact with each other through static mean fields of Lorentz scalar and vector character; these fields are produced by the scalar and number densities of the nucleons, so that the ground-state calculation is self-consistent. For simplicity, we consider only spherically symmetric ('doubly magic') nuclei with well-closed shells. (orig./HSI)

1991-01-01

99

Phase matching for third-harmonic generation in collisional magnetoplasmas  

International Nuclear Information System (INIS)

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

2005-11-01

100

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

Directory of Open Access Journals (Sweden)

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

Donatella Marazziti

2009-12-01

 
 
 
 
101

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

2004-03-30

102

Pharmacotherapy of impulsive aggression: a quality comparison of controlled studies.  

Science.gov (United States)

The present study assessed the quality of pharmacotherapy trials to treat impulsive aggressive behavior. While a search of the literature found 55 peer-reviewed published studies on the pharmacotherapy of aggression, only 23 met criteria for inclusion in the quality analysis. To be included in this review, the study must have had at least one comparison group to control for placebo effects. The study must have also adequately defined and diagnosed the presence of impulsive aggression or intermittent explosive disorder. The primary reason studies were excluded from the quality analysis was that impulsive aggression was not specifically defined as the behavior being treated (25 of 32, 78%). The results of the quality analysis found that higher quality studies (n=10; 45%) were characterized by a clear definition of impulsive aggression; specific criteria for what constitutes an impulsive aggressive act; the exclusion of participants with neurological disorders, serious mental disorders, and/or low IQ; and information concerning the serum levels of the medication being investigated. A significant weakness found in the literature is the paucity of high quality studies accessing the efficacy of pharmacological agents other than anticonvulsants for the treatment of impulsive aggression. PMID:23642319

Felthous, Alan R; Lake, Sarah L; Rundle, Brian K; Stanford, Matthew S

2013-01-01

103

Impulsivity and physical aggression: examining the moderating role of anxiety.  

Science.gov (United States)

Individuals vary in their propensity to engage in aggressive behaviors, and recent research has sought to identify individual differences that contribute to a person's propensity for physical aggression. Previous research has shown that impulsivity and aggression have a consistent relational pattern among many different samples. However, not all impulsive people will engage in aggressive behavior, perhaps because of other factors such as level of physiological arousal from anxiety. Specifically, one factor, namely physiological symptoms of anxiety such as those often associated with panic, may help as a predictor variable to be used in risk assessments or subclassification systems of aggression. Participants included 689 college students who completed self-report questionnaires assessing impulsivity, physical aggression, and anxiety. Multivariate hierarchical regression analyses were conducted. Greater scores on the measure of impulsivity were associated with higher levels of reported physical aggression. The interaction (impulsivity x anxiety) was not statistically significant, suggesting that impulsivity has the same effect on physical aggression regardless of the level of anxiety. There was a main effect for anxiety, which was associated with higher levels of reported physical aggression. Our findings may help inform typologies for identifying predictor variables used in risk assessment and treatment planning. PMID:24934013

Hatfield, Joshua; Dula, Chris S

2014-01-01

104

Dopamine-agonists and impulsivity in Parkinson's disease: impulsive choices vs. impulsive actions.  

Science.gov (United States)

The control of impulse behavior is a multidimensional concept subdivided into separate subcomponents, which are thought to represent different underlying mechanisms due to either disinhibitory processes or poor decision-making. In patients with Parkinson's disease (PD), dopamine-agonist (DA) therapy has been associated with increased impulsive behavior. However, the relationship among these different components in the disease and the role of DA is not well understood. In this imaging study, we investigated in PD patients the effects of DA medication on patterns of brain activation during tasks testing impulsive choices and actions. Following overnight withdrawal of antiparkinsonian medication, PD patients were studied with a H2 ((15)) O PET before and after administration of DA (1?mg of pramipexole), while they were performing the delay discounting task (DDT) and the GoNoGo Task (GNG). We observed that pramipexole augmented impulsivity during DDT, depending on reward magnitude and activated the medial prefrontal cortex and posterior cingulate cortex and deactivated ventral striatum. In contrast, the effect of pramipexole during the GNG task was not significant on behavioral performance and involved different areas (i.e., lateral prefrontal cortex). A voxel-based correlation analysis revealed a significant negative correlation between the discounting value (k) and the activation of medial prefrontal cortex and posterior cingulate suggesting that more impulsive patients had less activation in those cortical areas. Here we report how these different subcomponents of inhibition/impulsivity are differentially sensitive to DA treatment with pramipexole influencing mainly the neural network underlying impulsive choices but not impulsive action. PMID:24038587

Antonelli, Francesca; Ko, Ji Hyun; Miyasaki, Janis; Lang, Anthony E; Houle, Sylvain; Valzania, Franco; Ray, Nicola J; Strafella, Antonio P

2014-06-01

105

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

Directory of Open Access Journals (Sweden)

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.

ReinoutWiers

2010-09-01

106

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

Science.gov (United States)

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. PMID:21833213

Wiers, Reinout W; Ames, Susan L; Hofmann, Wilhelm; Krank, Marvin; Stacy, Alan W

2010-01-01

107

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

Science.gov (United States)

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

Tragesser, Sarah L; Robinson, R Joe

2009-08-01

108

Statistical investigation of transport barrier effects produced by biasing in a nonfusion magnetoplasma  

International Nuclear Information System (INIS)

The effects of a biasing potential on the statistical properties of the fluctuating flux, particle density and radial velocity time series in the nonfusion magnetoplasma Thorello [C. Riccardi, D. Xuantong, M. Salierno, L. Gamberale, and M. Fontanesi, Phys. Plasmas 4, 3749 (1997)] are studied. The shape evolution of the probability distribution function (PDF) of the temporal coarse-grained fluctuating flux is investigated as a function of the radial position in the plasma equatorial plane, for different values of the bias potential applied to a limiter. A reduction of cross correlations between density and radial velocity, concomitant with an increase in the shearing rate of the radial electric field, is found near the center of the plane as a function of the bias potential. The partial density-velocity cross correlations, evaluated at different time scales, reach their asymptotic values for times of the order of those describing the change in shape of the fluctuating flux PDF. The magnitude of the shearing rate of the radial electric field, calculated at different radial positions in the plane, is consistent with the expected decorrelation mechanism of turbulent transport

2004-10-01

109

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

International Nuclear Information System (INIS)

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

2014-04-01

110

Dust grain dynamics due to nonuniform and nonstationary high-frequency radiations in cold magnetoplasmas  

Directory of Open Access Journals (Sweden)

Full Text Available A general nonlinear theory for low-frequency electromagnetic field generation due to high-frequency nonuniform and nonstationary electromagnetic radiations in cold, uniform, multicomponent, dusty magnetoplasmas is developed. This theory permits us to consider the nonlinear action of all waves that can exist in such plasmas. The equations are derived for the dust grain velocities in the low-frequency nonlinear electric fields arising due to the presence of electromagnetic cyclotron waves travelling along the background magnetic field. The dust grains are considered to be magnetized as well as unmagnetized. Different regimes for the dust particle dynamics, depending on the spatio-temporal change of the wave amplitudes and plasma parameters, are discussed. It is shown that induced nonlinear electric fields can have both an electrostatic and electromagnetic nature. Conditions for maximum dust acceleration are found. The results obtained may be useful for understanding the possible mechanisms of dust grain dynamics in astrophysical, cosmic and laboratory plasmas under the action of nonuniform and nonstationary electromagnetic waves.

A. K. Nekrasov

2006-03-01

111

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

Science.gov (United States)

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.

Ali, S.; Ata-ur-Rahman

2014-04-01

112

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

Science.gov (United States)

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

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

2014-01-01

113

Impulse control disorders and depression.  

Science.gov (United States)

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

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

2002-05-01

114

Optimal Control of Volterra Equations with Impulses  

CERN Document Server

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

Belbas, S A

2004-01-01

115

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

Science.gov (United States)

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

2014-01-01

116

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

Science.gov (United States)

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 age, male sex, greater novelty seeking, impulsivity, depression and premorbid impulse control disorders as the most consistent risk factors. Such patients may warrant special monitoring after starting treatment with a DA. Various individual screening tools are available for people without Parkinson's disease. The Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease has been developed specifically for Parkinson's disease. The best treatment for impulse control disorders is prevention. However, after the development of impulse control disorders, the mainstay intervention is to reduce or discontinue the offending anti-Parkinsonian medication. In refractory cases, other pharmacological interventions are available, including neuroleptics, antiepileptics, amantadine, antiandrogens, lithium and opioid antagonists. Unfortunately, their use is only supported by case reports, small case series or open-label clinical studies. Prospective, controlled studies are warranted. Ongoing investigations include naltrexone and nicotine. PMID:23634190

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

2013-05-01

117

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

Science.gov (United States)

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 age, male sex, greater novelty seeking, impulsivity, depression and premorbid impulse control disorders as the most consistent risk factors. Such patients may warrant special monitoring after starting treatment with a DA. Various individual screening tools are available for people without Parkinson’s disease. The Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease has been developed specifically for Parkinson’s disease. The best treatment for impulse control disorders is prevention. However, after the development of impulse control disorders, the mainstay intervention is to reduce or discontinue the offending anti-Parkinsonian medication. In refractory cases, other pharmacological interventions are available, including neuroleptics, antiepileptics, amantadine, antiandrogens, lithium and opioid antagonists. Unfortunately, their use is only supported by case reports, small case series or open-label clinical studies. Prospective, controlled studies are warranted. Ongoing investigations include naltrexone and nicotine.

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

2013-01-01

118

Online Impulse Buying and Product Involvement  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

2008-01-01

119

Attractivity of nonlinear impulsive delay differential equations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The attractivity of nonlinear differential equations with time delays and impulsive effects is discussed. We obtain some criteria to determine the attracting set and attracting basin of the impulsive delay system by developing an impulsive delay differential inequality and introducing the concept of nonlinear measure. Examples and their simulations illustrate the effectiveness of the results and different asymptotical behaviors between the impulsive system and the corresponding continuous sys...

2006-01-01

120

Attractivity of nonlinear impulsive delay differential equations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The attractivity of nonlinear differential equations with time delays and impulsive effects is discussed. We obtain some criteria to determine the attracting set and attracting basin of the impulsive delay system by developing an impulsive delay differential inequality and introducing the concept of nonlinear measure. Examples and their simulations illustrate the effectiveness of the results and different asymptotical behaviors between the impulsive system and the corresponding continuous...

2006-01-01

 
 
 
 
121

Attractivity of nonlinear impulsive delay differential equations  

Directory of Open Access Journals (Sweden)

Full Text Available The attractivity of nonlinear differential equations with time delays and impulsive effects is discussed. We obtain some criteria to determine the attracting set and attracting basin of the impulsive delay system by developing an impulsive delay differential inequality and introducing the concept of nonlinear measure. Examples and their simulations illustrate the effectiveness of the results and different asymptotical behaviors between the impulsive system and the corresponding continuous system.

Zhichun Yang

2006-01-01

122

Emotion Regulation and Impulsivity in Young Adults  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Past research has linked both emotion regulation and impulsivity with the development and maintenance of addictions. However, no research has investigated the relationship between emotion regulation and impulsivity within young adults. In the present study, we analyzed 194 young adults (27.8% female; 21.3 ± 3.32 years old; 91.8% single; 85.1% Caucasian), grouping them as low, average, or high emotionally dysregulated, and compared self-reported impulsivity, impulsive behaviors (such as alcoh...

2012-01-01

123

Impulsive radio discharges near Saturn  

International Nuclear Information System (INIS)

An unexpected type of emission was observed during the Voyager 1 Saturn encounter. This consisted of periodic episodes of many impulsive discharges throughout the frequency range (20.4 kHz to 40.2 MHz) of the planetary radio astronomy experiment. (author)

1981-08-20

124

Impulse sales cooler. Final report  

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-11-15

125

Impulsivity, Frontal Lobes and Risk for Addiction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Crews, Fulton Timm; Boettiger, Charlotte Ann

2009-01-01

126

Full averaging of fuzzy impulsive differential inclusions  

Directory of Open Access Journals (Sweden)

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.

Natalia V. Skripnik

2010-09-01

127

Targeting impulsivity in Parkinson's disease using atomoxetine  

Science.gov (United States)

Noradrenergic dysfunction may play a significant role in cognition in Parkinson’s disease due to the early degeneration of the locus coeruleus. Converging evidence from patient and animal studies points to the role of noradrenaline in dopaminergically insensitive aspects of the parkinsonian dysexecutive syndrome, yet the direct effects of noradrenergic enhancement have not to date been addressed. Our aim was to directly investigate these, focusing on impulsivity during response inhibition and decision making. To this end, we administered 40 mg atomoxetine, a selective noradrenaline re-uptake inhibitor to 25 patients with Parkinson’s disease (12 female /13 male; 64.4 ± 6.9 years old) in a double blind, randomized, placebo controlled design. Patients completed an extensive battery of neuropsychological tests addressing response inhibition, decision-making, attention, planning and verbal short term memory. Atomoxetine improved stopping accuracy on the Stop Signal Task [F(1,19) = 4.51, P = 0.047] and reduced reflection impulsivity [F(1,9) = 7.86, P = 0.02] and risk taking [F(1,9) = 9.2, P = 0.01] in the context of gambling. The drug also conferred effects on performance as a function of its measured blood plasma concentration: it reduced reflection impulsivity during information sampling [adjusted R2 = 0.23, F(1,16) = 5.83, P = 0.03] and improved problem solving on the One Touch Stockings of Cambridge [adjusted R2 = 0.29, F(1,17) = 8.34, P = 0.01]. It also enhanced target sensitivity during sustained attention [F(1,9) = 5.33, P = 0.046]. The results of this exploratory study represent the basis of specific predictions in future investigations on the effects of atomoxetine in Parkinson’s disease and support the hypothesis that targeting noradrenergic dysfunction may represent a new parallel avenue of therapy in some of the cognitive and behavioural deficits seen in the disorder.

Housden, Charlotte R.; Regenthal, Ralf; Barker, Roger A.; Muller, Ulrich; Rowe, James; Sahakian, Barbara J.; Robbins, Trevor W.

2014-01-01

128

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

2013-08-01

129

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

Energy Technology Data Exchange (ETDEWEB)

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.

Chumak, O. V., E-mail: chuo@yandex.ru [Moscow State University, Sternberg Astronomical Institute (Russian Federation)

2013-08-15

130

Neuroanatomical and Neurochemical Basis of Impulsivity  

Directory of Open Access Journals (Sweden)

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

Kemal Yazici

2010-08-01

131

Laser impulse coupling at 130 fs  

International Nuclear Information System (INIS)

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

2006-04-30

132

Online Impulse Buying and Product Involvement  

Directory of Open Access Journals (Sweden)

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.

Tsai Chen

2008-12-01

133

Emotion regulation and impulsivity in young adults  

DEFF Research Database (Denmark)

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

Schreiber, Liana R N; Grant, Jon E

2012-01-01

134

UWB impulse radio for RFID  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In recent years RFID has become more and more widespread and is being used in an ever growing number of applications. Current RFID technology does however face some difïculties in several possible new applications. A change in technology is needed and in this thesis we will examine a very promising candidate, namely Ultra wide band Impulse radio (UWB-IR). To verify the viability of this technology a test chip has been made in 90 nm CMOS process.

Moen, Ha?vard

2006-01-01

135

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

Directory of Open Access Journals (Sweden)

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.

Donald M. Dougherty

2010-06-01

136

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

2005-10-01

137

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

International Nuclear Information System (INIS)

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

2013-02-01

138

EUV radiation from pinching discharges of magnetoplasma compressor type and its dependence on the dynamics of compression zone formation  

Science.gov (United States)

This paper is devoted to the investigation of plasma stream parameters and the intensity of extreme ultraviolet (EUV) radiation from the compression zone in various modes of operation of a magnetoplasma compressor (MPC). Two gases of different masses, either helium or argon, were used for the ignition of MPC discharge under the residual pressure. The plasma stream density along the axis and the EUV radiation energy were measured. It was shown that the compression zone position depends on the initial density of the residual gas. The EUV radiation energy was measured with a calibrated AXUV in the wavelength range of 12.2–15.8 nm. It was revealed that the radiation energy increased by 30–50% with decreasing initial gas pressure.

Garkusha, I. E.; Cherednychenko, T. N.; Ladygina, M. S.; Makhlay, V. A.; Petrov, Yu V.; Solyakov, D. G.; Staltsov, V. V.; Yelisyeyev, D. V.; Hassanein, A.

2014-05-01

139

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)

1966-01-01

140

Prueba de impulso cefálico / Head impulse test  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish 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.

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

 
 
 
 
141

Prueba de impulso cefálico Head impulse test  

Directory of Open Access Journals (Sweden)

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

Hayo A Breinbauer K

2011-08-01

142

A Review of Impulse Buying Behavior  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 aspe...

2013-01-01

143

Chaotification of complex networks with impulsive control  

Science.gov (United States)

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.

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

2012-06-01

144

Impulsiveness without discounting: the ecological rationality hypothesis.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Stephens, David W.; Kerr, Benjamin; Ferna?ndez-juricic, Esteban

2004-01-01

145

Design and Implementation of Impulse Distributed Waveform Generator – Time Interleaved Impulse Generator  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the design and implementation of impulse distributed waveform generator which generates UWB pulses with a bandwidth of 7GHz (1GHz to 8GHz.It utilizes time interleaved impulse generators to generate waveforms. Wide bandwidth is achieved by reducing the width of the impulses generated by time-interleaved impulse generators. Each of the impulse generators are triggered by the tunable delay unit which introduces the delay between the impulses generated. The Pulse shaping circuit shapes the impulses, by pulse amplitude tuning. The amplitude tuned impulses are combined together to obtain the waveform by using on-chip transmission line. Pulse width tuning and delay tuning makes this circuit reconfigurable. The pulse width can be tuned from 80ps to 1ns, and trigger delay can be varied from 30ps to 100ps.

S.Janaki

2013-06-01

146

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

1981-09-01

147

Impulsivity moderates the association between racial discrimination and alcohol problems.  

Science.gov (United States)

Alcohol use among university students is a serious public health concern, particularly among minority students who may use alcohol to cope with experiences of racial discrimination. Although the impact of racial discrimination on alcohol use has been well-established, individual differences in factors that may act to either attenuate or exacerbate the negative effects of racial discrimination are largely unknown. One potentially fruitful individual differences trait that has repeatedly been found to predict alcohol problems is the multidimensional personality trait of impulsivity. Nonetheless, the ways in which various aspects of impulsivity interact with racial discrimination is yet unknown. The current study, therefore, examined the joint and interactive contribution of racial discrimination and impulsivity in the prediction of alcohol consumption among racial minority university students. Participants included 336 Black/African-American and Asian/Asian-American university students. Results revealed both racial discrimination and impulsivity to be significantly associated with alcohol problems. Further, individuals' responses to racial discrimination were not uniform. Specifically, the association between racial discrimination and alcohol problems was moderated by lack of Premeditation; racial discrimination was most strongly predictive of alcohol problems for those who reported low level of premeditation. Findings from the present study highlight the importance of investigating risk factors for alcohol problems across multiple levels of the ecology as individual personality traits appear to relate to how one might respond to the experience of racial discrimination. PMID:24051137

Latzman, Robert D; Chan, Wing Yi; Shishido, Yuri

2013-12-01

148

An impulse radio communications system  

Science.gov (United States)

Pulson Communications has built a prototype impulse radio. The transmitter has an average power of 450 microwatts as measured out of the antenna. This prototype, transmitting high quality audio, was tested to ranges in excess of 7 kilometers. The potential range of this type of system at this power level may exceed 20 kilometers. The prototype had a center frequency of 675 MHz and an approximately equal bandwidth. We used a small wideband omni-directional antenna. While Pulson's laboratory hardware has been optimized for short range, there is no theoretical reason it could not be used for longer range communications, e.g., satellite-to-ground communications or interplanetary probes.

Withington, Paul, II; Fullerton, Larry W.

1993-01-01

149

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Broos, Nienke; Schmaal, Lianne; Wiskerke, Joost; Kostelijk, Lennard; Lam, Thomas; Stoop, Nicky; Weierink, Lonneke; Ham, Jannemieke; Geus, Eco J. C.; Schoffelmeer, Anton N. M.; Den Brink, Wim; Veltman, Dick J.; Vries, Taco J.; Pattij, Tommy; Goudriaan, Anna E.

2012-01-01

150

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

Directory of Open Access Journals (Sweden)

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

IrisMBalodis

2010-10-01

151

Synthesis of Room Impulse Responses for Variable Source Characteristics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

2011-01-01

152

Disciplinary Sanctioning of Impulsive University Students.  

Science.gov (United States)

Offers a rationale for the use of sanctions as a therapeutic strategy for impulsive college students. Describes problems encountered when implementing them. Notes that sanctions that help students control their impulses are actively therapeutic, not reactively punitive. Concludes, when sanctions remain firm, students can begin to realize that they…

Frederickson, Jon

1992-01-01

153

On Some New Impulsive Integral Inequalities  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2008-01-01

154

On Some New Impulsive Integral Inequalities  

Directory of Open Access Journals (Sweden)

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

Jianli Li

2008-10-01

155

Impulse-approximation Dirac optical potential  

International Nuclear Information System (INIS)

The impulse approximation to the Dirac optical potential for proton-nucleus elastic scattering is deduced from elementary considerations and found to be in remarkably good agreement with phenomenological parameters. The large difference between the real parts of scalar and vector optical potentials is explained by the impulse approximation

1983-05-09

156

On Some New Impulsive Integral Inequalities  

Directory of Open Access Journals (Sweden)

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

Li Jianli

2008-01-01

157

Meson theory of the dirac impulse approximation  

International Nuclear Information System (INIS)

A new formulation of the dirac impulse approximation is discussed which connects the p-nucleus optical potential to a dynamical description of the relativistic NN amplitude. Use of pseudovector ?N coupling eliminates rapid energy dependence found in the original impulse approximation. First calculations demonstrate success for 181 MeV with no loss of effectiveness at 500 and 800 MeV

1985-04-01

158

Temporal Preparation, Response Inhibition and Impulsivity  

Science.gov (United States)

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…

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

2010-01-01

159

Impulsivity makes more susceptible to overeating after contextual appetitive conditioning.  

Science.gov (United States)

Animals can learn that specific contexts are associated with important biological events such as food intake through classical conditioning. Very few studies suggest this is also possible in humans and contextual appetitive conditioning might even be a main determinant of habitual overeating in vulnerable humans. A Virtual Reality laboratory was used to test whether humans show conditioned responding (increased food desires and expectations, increased salivation and increased food intake) to a specific context after repeated pairings of this context with intake. It was also examined whether the personality trait impulsivity strengthens this contextual appetitive conditioning. Conditioned context-induced reactivity was indeed demonstrated and impulsivity predicted increased intake in only the intake-associated context. It is concluded that humans easily learn desires to eat in intake-related environments. The data also suggest that in particular more impulsive people are vulnerable for conditioned context-induced overeating. This relatively easy learning of associations between specific contexts and intake might stimulate habitual overeating and contribute to increased obesity prevalence. PMID:23831016

van den Akker, Karolien; Jansen, Anita; Frentz, Florentine; Havermans, Remco C

2013-11-01

160

CMOS Ultra Wide-Band Impulse Radio Receiver Front-End  

Digital Repository Infrastructure Vision for European Research (DRIVER)

As most radio communication is based on a narrow banded carrier tech­ nique, the technique this thesis is based on utilizes single impulse trans­missions and wide bandwidths. The technique is called Ultra WideBand Impulse Radio (UWB­IR) and is based on emission of single pulses and time domain processing. Through modulation and pulse shaping energy is contained within a specific band in the frequency spectrum. This implies that the technique is low power compared to narrow banded technique...

2005-01-01

 
 
 
 
161

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

Science.gov (United States)

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.

Stechlinski, Peter; Liu, Xinzhi

2011-11-01

162

Nonrelativistic quantum mechanics of the interacting particles and the coordinate-impulse correlation relations  

International Nuclear Information System (INIS)

A quantum mechanical model for a system of interacting bodies, taking into account noncommutativity of the coordinate and impulse operators for different particles and also the correlation equalities, is considered. The noncommutativity of the operators is here the result of the action of interparticle forces and represents natural generalization of the conventional commutation relation between the coordinate and impulse operators for a single particle. The efficiency of the model is evidenced by the specific calculations of well-known systems of atomic physics

2005-01-01

163

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Dell’osso, Bernardo; Altamura, A. Carlo; Allen, Andrea; Marazziti, Donatella; Hollander, Eric

2006-01-01

164

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

Science.gov (United States)

Impulsive phenomena have frequently been associated with personality disorders, beginning with Reich's description of the impulsive-character (Reich, 1925/1975). However, questions remain regarding the cooccurrence of a wide variety of impulsive phenomena and whether an underlying structure influences the differential association of impulses to individual personality disorders. Adults entering residential treatment for treatment-refractory disorders were interviewed about their lifetime histories of 33 impulse items, following independent diagnostic interviews. Factor analysis suggested 12 underlying dimensions of impulsive phenomena, explaining 68% of the variance. Borderline and antisocial PDs had the highest impulse scores, followed by self-defeating, narcissistic, depressive, and passive-aggressive PDs. Schizoid, avoidant, obsessive-compulsive, and dependent types were negatively associated with impulsive phenomena. Individuals with the highest impulse scores showed higher levels of borderline, antisocial and either self-defeating or passive-aggressive personality pathology, and were characterized by high Neuroticism and Openness and low Agreeableness on the NEO-FFI. Personality disorders and the NEO-FFI personality traits both predicted unique variance in impulsive phenomena, with the former predominating. Our findings bear striking similarities to Reich's (1925/1975) descriptions of the impulsive character. PMID:22023297

Perry, J Christopher; Körner, Annett C

2011-10-01

165

Impulsivity, Impulsive and Reflective Processes and the Development of Alcohol Use and Misuse in Adolescents and Young Adults  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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, alco...

Wiers, Reinout W.; Ames, Susan L.; Hofmann, Wilhelm; Krank, Marvin; Stacy, Alan W.

2010-01-01

166

Vector dissipativity theory for large-scale impulsive dynamical systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Modern complex large-scale impulsive systems involve multiple modes of operation placing stringent demands on controller analysis of increasing complexity. In analyzing these large-scale systems, it is often desirable to treat the overall impulsive system as a collection of interconnected impulsive subsystems. Solution properties of the large-scale impulsive system are then deduced from the solution properties of the individual impulsive subsystems and the nature of the impulsive system in...

Haddad Wassim M; Chellaboina VijaySekhar; Hui Qing; Nersesov Sergey

2004-01-01

167

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

Science.gov (United States)

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

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

2000-03-01

168

Colliding Plane Impulsive Gravitational Waves  

CERN Document Server

When two non-interacting plane impulsive gravitational waves undergo ahead-on collision, the vacuum interaction region between the waves after thecollision contains backscattered gravitational radiation from both waves. Thetwo systems of backscattered waves have each got a family of rays (nullgeodesics) associated with them. We demonstrate that if it is assumed that aparameter exists along each of these families of rays such that the modulus ofthe complex shear of each is equal then Einstein's vacuum field equations, withthe appropriate boundary conditions, can be integrated systematically to revealthe well-known solutions in the interaction region. In so doing the mysterybehind the origin of such solutions is removed. With the use of the fieldequations it is suggested that the assumption leading to their integration maybe interpreted physically as implying that the energy densities of the twobackscattered radiation fields are equal. With the use of different boundaryconditions this approach can lead to new c...

Barrabès, C; Hogan, P A

1999-01-01

169

Cylinder electrode plasma impulse accelerator  

International Nuclear Information System (INIS)

Electromagnetic acceleration of macroparticles to hypervelocities in axisymmetric geometry is throughly considered and a new type of the plasma impulse accelerator with cylinder electrode is proposed. The accelerator (CEPIAC) is consisted of the series of cylinders with these axes of symmetry on a straight line. The projectile should be charged in the second cylinder electrode together with the ablator when it is ready to be propelled. The projectile is propelled by JxB force of the plasma current along the surface of ablator which is in the rear of the projectile. Switches to close the successive circuits would not be necessary because the switching is automatically provided by the plasma generated on the ablator surface

1985-01-01

170

Identifying the facets of impulsivity that explain the relation between ADHD symptoms and substance use in a nonclinical sample.  

Science.gov (United States)

Adults with attention-deficit/hyperactivity disorder (ADHD) are at higher risk to use substances than their nonclinical peers. Increased levels of impulsivity are generally thought to contribute to their increased levels of risk. Impulsivity is a multifaceted construct, however, and little research to date has attempted to identify which facets of impulsivity contribute to the increased rates of substance abuse among individuals with ADHD. The current study examined the relation among ADHD symptom clusters (i.e., hyperactivity/impulsivity and inattention), substance use rates (i.e., alcohol use, nicotine use, and marijuana use), and personality processes associated with impulsive behavior in a group of young adults. Participants were 361 undergraduate students. Both symptom clusters were positively associated with rates of substance use. Specifically, hyperactive/impulsive symptoms were associated with alcohol and nicotine use, and inattentive symptoms were associated with alcohol use. Several pathways from hyperactive/impulsive symptoms to alcohol, nicotine, and marijuana use via specific facets of impulsivity were identified. These findings have implications for understanding the relation between ADHD symptoms and substance use, as well as clinical implications for preventing and treating substance use problems in individuals with symptoms of ADHD. PMID:24813555

Roberts, Walter; Peters, Jessica R; Adams, Zachary W; Lynam, Donald R; Milich, Richard

2014-08-01

171

Stability analysis of impulsive functional differential equations  

CERN Document Server

This book is devoted to impulsive functional differential equations which are a natural generalization of impulsive ordinary differential equations (without delay) and of functional differential equations (without impulses). At the present time the qualitative theory of such equationsis under rapid development. After a presentation of the fundamental theory of existence, uniqueness and continuability of solutions, a systematic development of stability theory for that class of problems is given which makes the book unique. It addresses to a wide audience such as mathematicians, applied research

Stamova, Ivanka

2009-01-01

172

Pathological gambling: an impulse control disorder? Measurement of impulsivity using neurocognitive tests.  

Science.gov (United States)

Pathological gambling is classified in the DSM-IV-TR (Diagnostic and Statistical Manual of Mental Disorders) and in the ICD-10 (International Classification of Disease) as an impulse control disorder. The association between impulsivity and pathological gambling remains a matter of debate: some researchers find high levels of impulsivity within pathological gamblers, others report no difference compared to controls, and yet others even suggest that it is lower. In this review we examine the relationship between pathological gambling and impulsivity assessed by various neurocognitive tests. These tests--the Stroop task, the Stop Signal Task, the Matching Familiar Figures Task, the Iowa Gambling Task, the Wisconsin Card Sorting Test, the Tower of London test, and the Continuous Performance Test--demonstrated less impulsivity in gambling behavior. The differences in performance between pathological gamblers and healthy controls on the neurocognitive tasks could be due to addictive behavior features rather than impulsive behavior. PMID:20803888

Dannon, Pinhas N; Shoenfeld, Netta; Rosenberg, Oded; Kertzman, Semion; Kotler, Moshe

2010-04-01

173

Obtaining Binaural Room Impulse Responses from B-Format Impulse Responses  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2008-01-01

174

Stability analysis of impulsive parabolic complex networks  

International Nuclear Information System (INIS)

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

2011-11-01

175

Transmission Channel Characterization by Impulse Response Measurements.  

Science.gov (United States)

Some basic concepts, design criteria and hardware implementation are reviewed for measuring the impulse responses which characterize radio transmission channels. A channel sounder which is presently being used by the Institute for Telecommunication Scienc...

R. F. Linfield R. W. Hubbard L. E. Pratt

1976-01-01

176

Impulsive waves in the Nariai universe  

CERN Document Server

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. Due to the topology of the latter, the wave front consists of two non-expanding spheres. Special sub-classes 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.

Ortaggio, M

2002-01-01

177

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)

2012-05-01

178

Impulsive frotteurism: a case report.  

Science.gov (United States)

Frotteurism is a perverted sexual behaviour wherein the person tends to rub or bring about physical contact between his genitals and an unrelated female or male to derive sexual pleasure. Moreover, frotteurism is a common phenomenon among the general population which usually goes unnoticed or overlooked. Nevertheless, public frottage has legal implications in almost all countries over the world. But, when frotteurism manifests on the backdrop of psychiatric illness or as a developmental abnormality then it is worth discussing what the legal liability would be. The present case report is based on hypersexual frotteuristic behaviour manifested on the background of a concealed psychiatric illness, featuring depression and obsessive compulsive disease. The hypersexual behaviour manifested in the form of masturbation with features of frotteurism and subsequent development of depression. Nevertheless, compulsive manifestation of frotteuristic behaviour and subsequent development of morbid depression is rare. This paper describes a 12-year-old boy having unrestrained impulsive frotteurism with his peers, school mates and with his younger brother. He was conscious of the fact and feeling guilty of what he was doing but unable to restrain himself. It was followed by the development of symptoms of depression which was treated with Sertraline. Concurrent psychiatric counseling and rehabilitation measures were taken too. There was complete remission of the symptoms 6 months after the onset of treatment and without relapse thereafter. The paper discusses the differential diagnosis and management of hypersexual behaviour. PMID:23929674

Patra, Ambika Prasad; Bharadwaj, Balaji; Shaha, Kusa Kumar; Das, Siddhartha; Rayamane, Anand P; Tripathi, Chandra Sekhara

2013-10-01

179

Multi-impulsivity of Japanese patients with eating disorders: primary and secondary impulsivity.  

Science.gov (United States)

Several studies have noted that multi-impulsive bulimia nervosa tends to be refractory to treatment. However, it is not known whether these impulsivities are an expression of more fundamental psychopathology or simply the consequence of chaotic eating behaviors. Studies of the temporal relationship between the onset of eating disorder and the occurrence of impulsive behaviors will facilitate a better understanding of these issues. Subjects consisted of 60 patients with anorexia nervosa restricting type (AN-R), 62 patients with anorexia nervosa binge-eating/purging type (AN-BP), 114 patients with bulimia nervosa purging type (BN) and 66 control subjects. Impulsive behaviors and childhood traumatic experiences were assessed by self-report questionnaire. Multi-impulsivity (defined by at least three of the following: heavy regular alcohol drinking; suicide attempt; self-mutilation; repeated shoplifting of items other than food; sexual relationships with persons not well known to the subject) was found in 2% of AN-R, 11% of AN-BP, 18% of BN and 2% of control subjects. Eighty percent of BN patients with multi-impulsivity had a history of suicide attempts or self-mutilation history prior to the onset of bulimia nervosa. In BN patients, there tended to be a relationship between childhood parental loss or borderline personality disorder and multi-impulsivity. In conclusion, primary impulsivity (chronological prior occurrence of impulsive behaviors) does exist even in a very different culture, although the number of patients of this type is very limited. PMID:10889288

Nagata, T; Kawarada, Y; Kiriike, N; Iketani, T

2000-07-17

180

The relationship between impulsivity and impulse control disorders in Parkinson's disease.  

Science.gov (United States)

A range of behaviors presumed to be related to dopaminergic medications have been recently recognized in Parkinson's disease (PD). We evaluated 50 consecutive cognitively intact PD patients on stable dopamine agonist and levodopa therapy and 100 healthy controls for compulsive sexual behavior, compulsive buying, or intermittent explosive disorders assessed by the Minnesota Impulsive Disorders Interview (MIDI), pathological gambling (South Oaks Gambling Screen, SOGS), impulsivity (Barratt Impulsiveness Scale), compulsivity (Maudsley obsessional-compulsive inventory), and depression scores (Geriatric Depression Scale). Overall 28% PD (14/50) and 20% healthy controls (20/100) reported at least one abnormal behavior at MIDI or pathological SOGS score. PD patients had higher scores than controls for impulsivity (P = 0.006), compulsivity (P impulsivity, compulsivity, and depression scores in PD. Male gender and higher impulsivity score, but not dose and kind of dopaminergic medications, were associated in PD with increased probability of impulsive disorders at MIDI. Impulse control disorders are also common in the control population. Individual susceptibility factors, such as high impulsivity and depression, underline abnormal behaviors in PD patients treated with stable dopaminergic therapy. PMID:18067187

Isaias, Ioannis U; Siri, Chiara; Cilia, Roberto; De Gaspari, Danilo; Pezzoli, Gianni; Antonini, Angelo

2008-02-15

 
 
 
 
181

Robust Impulsive Synchronization of Discrete Dynamical Networks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We aim to study robust impulsive synchronization problem for uncertain discrete dynamical networks. For the discrete dynamical networks with unknown but bounded network coupling, we will design some robust impulsive controllers which ensure that the state of a discrete dynamical network asymptotically synchronize with an arbitrarily assigned state of an isolate node of the network. Three representative examples are also worked through to illustrate our results.

Ming Lei; Bin Liu

2008-01-01

182

Impulse control problem with switching technology  

CERN Document Server

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.

Amami, Rim

2010-01-01

183

Impulsive nature in collisional driven reconnection  

Energy Technology Data Exchange (ETDEWEB)

Compressible magnetohydrodynamic simulation is carried out in order to investigate energy relaxation process of the driven magnetic reconnection in an open finite system through a long time calculation. It is found that a very impulsive energy release occurs in an intermittent fashion through magnetic reconnection for a continuous magnetic flux injection on the boundary. In the impulsive phase, the reconnection rate is remarkably enhanced up to more than ten times of the driving rate on the boundary. (author).

Kitabata, Hideyuki; Hayashi, Takaya; Sato, Tetsuya

1995-11-01

184

Nonlocal Impulsive Cauchy Problems for Evolution Equations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Of concern is the existence of solutions to nonlocal impulsive Cauchy problems for evolution equations. Combining the techniques of operator semigroups, approximate solutions, noncompact measures and the fixed point theory, new existence theorems are obtained, which generalize and improve some previous results since neither the Lipschitz continuity nor compactness assumption on the impulsive functions is required. An application to partial differential equations is also presented.

2011-01-01

185

Nonlocal Impulsive Cauchy Problems for Evolution Equations  

Directory of Open Access Journals (Sweden)

Full Text Available Of concern is the existence of solutions to nonlocal impulsive Cauchy problems for evolution equations. Combining the techniques of operator semigroups, approximate solutions, noncompact measures and the fixed point theory, new existence theorems are obtained, which generalize and improve some previous results since neither the Lipschitz continuity nor compactness assumption on the impulsive functions is required. An application to partial differential equations is also presented.

Liang Jin

2011-01-01

186

Impulsive nature in magnetohydrodynamic driven reconnection  

International Nuclear Information System (INIS)

Compressible magnetohydrodynamic simulation is carried out in order to investigate energy relaxation process of the driven magnetic reconnection in an open finite system through a long time calculation. It is found that a very impulsive energy release occurs in an intermittent fashion through magnetic reconnection for a continuous magnetic flux injection on the boundary. In the impulsive phase, the reconnection rate is remarkably enhanced up to more than ten times of the driving rate on the boundary. (author)

1996-10-01

187

Impulsive nature in collisional driven reconnection  

International Nuclear Information System (INIS)

Compressible magnetohydrodynamic simulation is carried out in order to investigate energy relaxation process of the driven magnetic reconnection in an open finite system through a long time calculation. It is found that a very impulsive energy release occurs in an intermittent fashion through magnetic reconnection for a continuous magnetic flux injection on the boundary. In the impulsive phase, the reconnection rate is remarkably enhanced up to more than ten times of the driving rate on the boundary. (author)

1995-01-01

188

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

Directory of Open Access Journals (Sweden)

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.

Aleksandra Krasowska,

2013-07-01

189

Clinical aspects of impulsive compulsive behaviours in Parkinson's disease.  

Science.gov (United States)

Impulsive-compulsive behaviours (ICBs) are an increasingly well-recognised adverse-effect of dopaminergic medications used to treat Parkinson's disease. ICBs include pathological gambling, compulsive sexual behaviour, compulsive buying, and binge eating, together with punding and the addiction-like compulsive use of dopamine replacement therapy, or dopamine dysregulation syndrome. The prevalence of ICBs was approximately 14% in a large study undertaken in specialist movement disorder clinics. Dopamine dysregulation syndrome is more associated with compulsive l-dopa use, whereas other ICBs are more linked with oral dopamine agonist use. Other mechanisms implicated in the development and perpetuation of ICBs in PD include aberrant learning from reward-related situations, including decreased learning from negative feedback, increased measures of impulsivity or sensation seeking, and strong preference for immediate over future rewards. Treatment options for impulsive-compulsive behaviours include pharmacological, surgical and psychological interventions. The early recognition and prevention of ICBs, coupled with awareness of clinical risk factors for the development of these behaviours is of paramount importance, given the lack of specific treatments for these sometimes debilitating behaviours. PMID:21839478

Djamshidian, Atbin; Averbeck, Bruno B; Lees, Andrew J; O'Sullivan, Sean S

2011-11-15

190

Sandia National Laboratories' high power electromagnetic impulse sources  

Science.gov (United States)

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

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

1994-05-01

191

The coherent Cerenkov radiated power from a group of field-aligned test particles in a magnetoplasma  

Science.gov (United States)

An expression is derived that describes the coherent Cerenkov radiated power from a group of test particles in a plasma medium moving parallel to a magnetic field. In this analysis, each particle has an arbitrary position and velocity along a field line and, as a consequence, both the spatial and temporal coherence of the radiation are considered. As an example, it is demonstrated that a monoenergetic electron beam consisting of small pulses can generate wave powers well above incoherent levels if the pulse spacing is comparable to an integer number of emission wavelengths. It is also shown that, if the beam particles have a velocity spread, Delta-V, the wave powers will decrease in time due to the reduced temporal coherence of the particle radiators, where this coherence scales as 1/Delta-V. This latter effect applies to any charged particle beam propagating in a magnetoplasma, because even an initially monoenergetic beam becomes thermalized by electrostatic wave-particle interactions reducing the radiated power.

Farrell, W. M.; Goertz, C. K.

1990-01-01

192

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)

2007-01-01

193

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

International Nuclear Information System (INIS)

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

2013-11-01

194

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2013-11-15

195

Anger and Impulsivity in Adolescents Attempting Suicide  

Directory of Open Access Journals (Sweden)

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

Elif AKIN

2012-01-01

196

New cut-off frequency for low-frequency electromagnetic waves in a multi-ion magnetoplasma with charged dust particulates  

Energy Technology Data Exchange (ETDEWEB)

Properties of low-frequency electromagnetic waves propagating in a multi-ion magnetoplasma with an ensemble of negatively charged stationary dust particles are investigated. It is found that the combined effects of negatively charged stationary dust particles and additional ion-species do not only significantly modify the existing cut-off and resonance frequencies, but also introduce a new cut-off frequency for the low-frequency electromagnetic waves. New laboratory experiments in a magnetized plasma with two-ion species and a dust component should be conducted to verify our theoretical predictions.

Mamun, A.A.; Shukla, P.K.; Morfill, G.E

2004-03-15

197

[Impulsivity and compulsivity in cocaine dependent individuals].  

Science.gov (United States)

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

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

2012-01-01

198

Plasma properties in high power impulse magnetron sputtering  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2008-01-01

199

Serotonin depletion induces 'waiting impulsivity' on the human four-choice serial reaction time task: cross-species translational significance.  

Science.gov (United States)

Convergent results from animal and human studies suggest that reducing serotonin neurotransmission promotes impulsive behavior. Here, serotonin depletion was induced by the dietary tryptophan depletion procedure (TD) in healthy volunteers to examine the role of serotonin in impulsive action and impulsive choice. We used a novel translational analog of a rodent 5-choice serial reaction time task (5-CSRTT)-- the human 4-CSRTT--and a reward delay-discounting questionnaire to measure effects on these different forms of 'waiting impulsivity'. There was no effect of TD on impulsive choice as indexed by the reward delay-discounting questionnaire. However, TD significantly increased 4-CSRTT premature responses (or impulsive action), which is remarkably similar to the previous findings of effect of serotonin depletion on rodent 5-CSRTT performance. Moreover, the increased premature responding in TD correlated significantly with individual differences on the motor impulsivity subscale of the Barratt Impulsivity Scale. TD also improved the accuracy of performance and speeded responding, possibly indicating enhanced attention and reward processing. The results suggest: (i) the 4-CSRTT will be a valuable addition to the tests already available to measure impulsivity in humans in a direct translational analog of a test extensively used in rodents; (ii) TD in humans produces a qualitatively similar profile of effects to those in rodents (ie, enhancing premature responding), hence supporting the conclusion that TD in humans exerts at least some of its effects on central serotonin; and (iii) this manipulation of serotonin produces dissociable effects on different measures of impulsivity, suggesting considerable specificity in its modulatory role. PMID:24385133

Worbe, Yulia; Savulich, George; Voon, Valerie; Fernandez-Egea, Emilio; Robbins, Trevor W

2014-05-01

200

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

Science.gov (United States)

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

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

2011-01-01

 
 
 
 
201

Impulsive-compulsive buying disorder: clinical overview.  

Science.gov (United States)

Impulsive-compulsive buying disorder (ICBD) is an impulse control disorder not otherwise specified (ICD-NOS) characterized by impulsive drives and compulsive behaviours (buying unneeded things), personal distress, impaired social and vocational functioning and financial problems. Despite being described in the 19th century, serious attention to ICBD began only in the last decade with the first epidemiological and pharmacological investigation. Biological, social and psychological factors contribute to the aetiology of ICBD. Cognitive-behavioural therapy and selective serotonin re-uptake inhibitors are currently considered the more effective interventions in the treatment of ICBD. The present review aims to provide a broad overview of the epidemiology, aetiology, phenomenology and treatment options of ICBD. PMID:18330768

Dell'Osso, Bernardo; Allen, Andrea; Altamura, A Carlo; Buoli, Massimiliano; Hollander, Eric

2008-04-01

202

Almost periodic solutions of impulsive differential equations  

CERN Document Server

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.

Stamov, Gani T

2012-01-01

203

Generalized impulse approximation for relativistic proton scattering  

International Nuclear Information System (INIS)

A complete set of Lorentz invariant nucleon-nucleon amplitudes, based on a meson-exchange model and on-mass-shell kinematics, is used to construct the impulse approximation optical potential for use in the Dirac equation. Relativistic nuclear densities are also used in the construction. No free parameters enter. The analysis provides a dynamical basis for the virtual pair couplings which are implicit in the Dirac equation for proton-nucleus scattering. A momentum space potential and a localized potential suitable for coordinate space analysis are developed. Initial numerical calculations are presented for proton scattering by /sup 40/Ca at 200, 500, and 800 MeV. The generalized impulse approximation provides a successful description of the elastic scattering data for these cases. Low energy results are improved substantially in comparison with the original form of Dirac impulse approximation based on using five Fermi amplitudes to represent nucleon-nucleon scattering

1987-01-01

204

Impulse holograms in amorphous semiconductor films  

International Nuclear Information System (INIS)

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

2002-01-01

205

Impulsive differential equations with a small parameter  

CERN Document Server

This book is devoted to impulsive differential equations with a small parameter. It consists of three chapters. Chapter One serves as an introduction. In Chapter Two, regularly perturbed impulsive differential equations are considered. Modifications of the method of small parameter, the averaging method, and the method of integral manifolds are proposed. In Chapter Three, singularly perturbed differential equations are considered. A modification of the method of boundary functions is proposed, and asymptotic expansions along the powers of the small parameters of the solutions of the initial va

Bainov, DD

1994-01-01

206

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)

2010-01-15

207

The relationship between impulse control disorders and obsessive-compulsive disorder: a current understanding and future research directions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Impulse control disorders (ICDs) constitute a heterogeneous group of conditions linked diagnostically by difficulties in resisting “the impulse, drive, or temptation to perform an act that is harmful to the person or to others.” Specific ICDs share clinical, phenomenological and biological features with obsessive-compulsive disorder (OCD) that have suggested that these disorders might be categorized together. However, other data suggest significant differences between OCD and ICDs. In thi...

Potenza, Marc Nicholas; Koran, Lorrin Michael; Pallanti, Stefano

2009-01-01

208

A new Calculation Procedure for Spatial Impulse Responses in Ultrasound  

DEFF Research Database (Denmark)

A new procedure for the calculation of spatial impulse responses for linear sound fields is introduced. This calculation procedure uses the well known technique of calculating the spatial impulse response from the intersection of a circle emanating from the projected spherical wave with the boundary of the emitting aperture. This general result holds for all aperture boundaries for a flat transducer surface, and this is used in the procedure to yield the response for all types of flat transducers. An arbitrary apodization function over the aperture can be incorporated through a simple one-dimensional integration. The case of a soft baffle mounting of the aperture is also included. Specific solutions for transducer boundaries made from lines are given, so that any polygon transducer can be handled. Specific solutions for circles are also given. Finally, a solution for a general boundary is stated, and all these boundary elements can be combined to, e.g., handle annular arrays or semi-circle transducers. Results from an implementation of the approach are given and compared to previously developed solutions for a simple aperture, a complex aperture, and a Gaussian apodized circular transducer.

Jensen, Jørgen Arendt

1999-01-01

209

Stability and Stabilization of Impulsive Stochastic Delay Difference Equations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 cri...

2010-01-01

210

Relationship between impulsivity and decision-making in cocaine dependence  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Impulsivity and decision-making are associated on a theoretical level in that impaired planning is a component of both. However, few studies have examined the relationship between measures of decision-making and impulsivity in clinical populations. The purpose of this study was to compare cocaine-dependent subjects to controls on a measure of decision-making (the Iowa Gambling Task or IGT), a questionnaire measure of impulsivity (the Barratt Impulsiveness Scale or BIS-11), and a measure of be...

Kjome, Kimberly L.; Lane, Scott D.; Schmitz, Joy M.; Green, Charles; Ma, Liangsuo; Prasla, Irshad; Swann, Alan C.; Moeller, F. Gerard

2010-01-01

211

Nonlinear RLS algorithm for impulsive CDMA channels  

Science.gov (United States)

Multiuser detection constitutes a class of advanced interference mitigation techniques for increasing the capacity of CDMA communication systems. Thus far, the work has been carried out under the Gaussian noise assumption for analytical convenience and yet physical noise encountered in real-life channels is impulsive and decidedly non-Gaussian. Since Gaussian signal processing schemes can perform poorly in impulsive noise, the applicability and performance of such multiuser detectors in realistic channels become strongly questionable. This paper addresses the development of non-Gaussian techniques for CDMA communications, by first examining the performance degradation of Linear Gaussian-based multiuser detectors in impulsive noise and then by presenting a series of nonlinear techniques to yield a more robust performance. A common approach to linear adaptive interference suppression in Direct Sequence CDMA is based on the Least Mean Square (LMS) or Recursive Least Square (RLS) algorithms to capture the cyclo-stationarity of multiple access interference (MAI) adaptively, mostly under the minimum mean squared error (MMSE) criterion. However, under impulsive noise environments, the performance of the conventional RLS algorithm deteriorates substantially, and therefore, a robust algorithm based on nonlinear RLS is suggested to obtain a modified CDMA receiver structure. Simulation results are presented to demonstrate that the proposed modified nonlinear RLS algorithm significantly outperforms the conventional RLS algorithm whilst it maintains comparable performance in Gaussian channels.

Sharif, Bayan S.; Chuah, Teong C.; Hinton, Oliver R.; Jimaa, Shihab A.

2003-08-01

212

Dopamine, Time, and Impulsivity in Humans  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2010-01-01

213

Impulse noise trauma during army weapon firing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

1997-01-01

214

Modification of Impulsivity: Implications for Teaching  

Science.gov (United States)

Cites studies showing that impulsive children can perform more reflectively with respect to response time and/or accuracy if exposed to reflective models, self-verbalization strategies, increased concern over performance accuracy, and training in attention deployment, delay of response and visual discrimination. (BF/JH)

Margolis, Howard; And Others

1977-01-01

215

Impulsivity and strategy transfer: metamemory as mediator.  

Science.gov (United States)

Acquisition, maintenance, and generalization of organizational strategies were studied as a function of impulsivity-reflectivity and metamemory. In Experiment 1, 64 second- and third-grade children, identified as impulsive or reflective, participated in strategy training and transfer sessions; 25 children in a control condition received the same tasks without strategy training. Strategy and metamemory scores were significantly higher for reflective than impulsive children. Metamemory predicted strategic behavior when cognitive tempo was removed. In Experiment 2, 80 children were given an expanded metamemory battery designed to assess verbalized knowledge of memory processes. Children in the experimental condition were trained to use an organizational strategy and later tested for its maintenance and transfer. Strategy scores were higher for the reflective children during transfer but not training, suggesting a relationship between cognitive tempo and the ability to use strategies in new contexts. Reflective children were again found to have higher metamemory scores. The correlation between metamemory and strategy use with cognitive tempo partialed out was significant, whereas the tempo-strategy use correlation was nonsignificant when metamemory was removed. Strategy maintenance and generalization in impulsive and reflective children appear mediated by metamemorial processes. PMID:6872634

Borkowski, J G; Peck, V A; Reid, M K; Kurtz, B E

1983-04-01

216

Characterization of Horizontal Impulse Accelerator Pin Profiles.  

Science.gov (United States)

Tests were run on the AFRL/HEPA Horizontal Impulse Accelerator (HIA) to document the dynamic response of 31 available metering pins. These interchangeable pins regulate the flow of gas through the HIA and produce an acceleration pulse unique to each pin. ...

J. P. Strzelecki

2005-01-01

217

Skin Friction Gauge for Impulsive Flows.  

Science.gov (United States)

A new skin friction gauge has been designed for use in impulsive facilities. The gauge was tested in the T4 free piston shock tunnel, at the University of Queensland, using a 1.5 m long plate that formed one of the inner walls of a rectangular duct. The t...

C. P. Goyne A. Paull R. J. Stalker

1995-01-01

218

Impulse response of a nonlinear dispersive wave  

International Nuclear Information System (INIS)

The spatiotemporal instability of a nonlinear wave is studied by applying impulse-response analysis. The time-asymptotic Green function is obtained analytically for both modulationally stable and unstable cases. The conditions for absolute and convective instability are found analytically, as is the frequency region for amplification and the spatial and temporal growth rates. (c) 1995 The American Physical Society

1995-12-01

219

Relative impulse approximation for antiproton scattering  

International Nuclear Information System (INIS)

A comparison is made between the relativistic and non-relativistic impulse approximation predictions for the differential cross-section and polarization observables for antiproton scattering off 40Ca at Tsub(lab) = 180 MeV. It is found that for the model considered here a clear distinction between these two approximations can only be made on the basis of polarization measurements. (author)

1985-01-01

220

Synchronizing Method for Impulse Radio Network  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In IR (Impulse Radio) network, the conventional synchronization (also called signal acquisition) method becomes inefficient and results in a certain failure of synchronization when concurrent transmissions are allowed without controlling their powers. The present invention aims to solve this problem by introducing a novel synchronization method. Moreover, the claimed method can replace the conventional one in all IR networks.

El Fawal, Alaeddine; Le Boudec, Jean-yves

2005-01-01

 
 
 
 
221

Synchronizing Method for Impulse Radio Network  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In IR (Impulse Radio) network, the conventional synchronization (also called signal acquisition) method becomes inefficient and results in a certain failure of synchronization when concurrent transmissions are allowed without controlling their powers. The present invention aims to solve this problem by introducing a novel synchronization method. Moreover, the claimed method can replace the conventional one in all IR networks.

El Fawal, Alaeddine; Le Boudec, Jean-yves

2004-01-01

222

Impulse Formulations of Hall Magnetohydrodynamic Equations  

CERN Multimedia

Impulse formulations of Hall magnetohydrodynamic (MHD) equations are developed. The Lagrange invariance of a generalized 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 show not to affect, as to be expected, the physical implications of the generalized magnetic helicity invariant.

Shivamoggi, Bhimsen K

2008-01-01

223

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.

2011-11-30

224

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

Science.gov (United States)

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 veloc...

G. Petrov

1992-01-01

225

'Impulsive compulsivity' in obsessive-compulsive disorder: a phenotypic marker of patients with poor clinical outcome.  

Science.gov (United States)

Although traditionally obsessive-compulsive disorder (OCD) and impulse control disorders (ICD) have represented opposing ends of a continuum, recent research has demonstrated a frequent co-occurrence of impulsive and compulsive behaviours, which may contribute to a worse clinical picture of some psychiatric disorders. We hypothesize that individuals with 'impulsive' OCD as characterized by poor insight, low resistance, and reduced control towards their compulsions will have a deteriorative course, greater severity of hoarding and/or symmetry/ordering symptoms, and comorbid ICD and/or substance use disorders (SUD). The sample consisted of 869 individuals with a minimum score of 16 on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). Of these, 65 had poor insight, low resistance, and reduced control towards compulsions ('poor IRC') and 444 had preserved insight, greater resistance and better control over compulsions ('good IRC'). These two groups were compared on a number of clinical and demographic variables. Individuals with poor IRC were significantly more likely to have a deteriorative course (p buying (p = 0.040). Regression analysis revealed that duration of obsessions (p = 0.037) and hoarding severity (p = 0.005) were significant predictors of poor IRC. In the absence of specific measures for impulsivity in OCD, the study highlights the utility of simple measures such as insight, resistance and control over compulsions as a phenotypic marker of a subgroup of OCD with impulsive features demonstrating poor clinical outcome. PMID:22647523

Kashyap, Himani; Fontenelle, Leonardo F; Miguel, Euripedes C; Ferrão, Ygor A; Torres, Albina R; Shavitt, Roseli G; Ferreira-Garcia, Rafael; do Rosário, Maria C; Yücel, Murat

2012-09-01

226

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

Science.gov (United States)

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

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

2014-06-30

227

New stability criterion for delayed neural networks with impulses  

Energy Technology Data Exchange (ETDEWEB)

This paper studies the exponential stability of impulsive delayed neural networks (IDNN). By employing the standard Lyapunov function and the modified Halanay inequalities, two new sufficient conditions guaranteeing the global exponential stability of the origin of IDNN are established. The proposed results characterize the effects of impulses, delay and the exponential convergence rate of the impulse-free DNN in an aggregated form.

Shen, J; Wan, J; Li, C [School of Computer, Hangzhou Dianzi University, Hangzhou 310018 (China)], E-mail: licd@cqu.edu.cn

2008-02-15

228

New stability criterion for delayed neural networks with impulses  

Science.gov (United States)

This paper studies the exponential stability of impulsive delayed neural networks (IDNN). By employing the standard Lyapunov function and the modified Halanay inequalities, two new sufficient conditions guaranteeing the global exponential stability of the origin of IDNN are established. The proposed results characterize the effects of impulses, delay and the exponential convergence rate of the impulse-free DNN in an aggregated form.

Shen, J.; Wan, J.; Li, C.

2008-02-01

229

New stability criterion for delayed neural networks with impulses  

International Nuclear Information System (INIS)

This paper studies the exponential stability of impulsive delayed neural networks (IDNN). By employing the standard Lyapunov function and the modified Halanay inequalities, two new sufficient conditions guaranteeing the global exponential stability of the origin of IDNN are established. The proposed results characterize the effects of impulses, delay and the exponential convergence rate of the impulse-free DNN in an aggregated form

2008-02-01

230

Dwell-time conditions for robust stability of impulsive systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Dashkovskiy, Sergey; Mironchenko, Andrii

2012-01-01

231

H? Control of Fuzzy Impulsive Systems with Quantized Feedback  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper is concerned with the problem of H? control of fuzzy nonlinear impulsive systems with quantized feedback. New results on the H? feedback control are established for one class of fuzzy nonlinear uncertain impulsive systems and one class of fuzzy nonlinear impulsive systems with nonlinear...

Yingqi Zhang; Caixia Liu

2009-01-01

232

Teaching Emotional Intelligence to Impulsive-Aggressive Youth.  

Science.gov (United States)

Describes complex issues involved in helping impulsive-aggressive youth who are devoid of emotional intelligence. Reviews anatomy of impulsivity and the irrational beliefs used as defense mechanisms by impulsive-aggressive students. Discusses two alternative intervention strategies, Life Space Crisis Intervention techniques and the Self Control…

Henley, Martin; Long, Nicholas J.

1999-01-01

233

Stability analysis of impulsive functional systems of fractional order  

Science.gov (United States)

In this paper, a class of impulsive fractional functional differential systems is investigated. Sufficient conditions for stability of the zero solution are proved, extending the corresponding theory of impulsive functional differential equations. The investigations are carried out by using the comparison principle, coupled with the Lyapunov function method. We apply our results to an impulsive single species model of Lotka-Volterra type.

Stamova, Ivanka; Stamov, Gani

2014-03-01

234

On Exact Controllability of First-Order Impulsive Differential Equations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Many dynamical systems have an impulsive dynamical behavior due to abrupt changes at certain instants during the evolution process. The mathematical description of these phenomena leads to impulsive differential equations. In this work, we present some new results concerning the exact controllability of a nonlinear ordinary differential equation with impulses.

2010-01-01

235

On Exact Controllability of First-Order Impulsive Differential Equations  

Directory of Open Access Journals (Sweden)

Full Text Available Many dynamical systems have an impulsive dynamical behavior due to abrupt changes at certain instants during the evolution process. The mathematical description of these phenomena leads to impulsive differential equations. In this work, we present some new results concerning the exact controllability of a nonlinear ordinary differential equation with impulses.

Juan J. Nieto

2010-01-01

236

Nonlinear impulsive Volterra integral equations in Banach spaces and applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

1993-01-01

237

On some impulsive fractional differential equations in Banach spaces  

Directory of Open Access Journals (Sweden)

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.

W. Wei

2010-01-01

238

Nonlinear impulsive Volterra integral equations in Banach spaces and applications  

Directory of Open Access Journals (Sweden)

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

Dajun Guo

1993-01-01

239

Premotor functional connectivity predicts impulsivity in juvenile offenders.  

Science.gov (United States)

Teenagers are often impulsive. In some cases this is a phase of normal development; in other cases impulsivity contributes to criminal behavior. Using functional magnetic resonance imaging, we examined resting-state functional connectivity among brain systems and behavioral measures of impulsivity in 107 juveniles incarcerated in a high-security facility. In less-impulsive juveniles and normal controls, motor planning regions were correlated with brain networks associated with spatial attention and executive control. In more-impulsive juveniles, these same regions correlated with the default-mode network, a constellation of brain areas associated with spontaneous, unconstrained, self-referential cognition. The strength of these brain-behavior relationships was sufficient to predict impulsivity scores at the individual level. Our data suggest that increased functional connectivity of motor-planning regions with networks subserving unconstrained, self-referential cognition, rather than those subserving executive control, heightens the predisposition to impulsive behavior in juvenile offenders. To further explore the relationship between impulsivity and neural development, we studied functional connectivity in the same motor-planning regions in 95 typically developing individuals across a wide age span. The change in functional connectivity with age mirrored that of impulsivity: younger subjects tended to exhibit functional connectivity similar to the more-impulsive incarcerated juveniles, whereas older subjects exhibited a less-impulsive pattern. This observation suggests that impulsivity in the offender population is a consequence of a delay in typical development, rather than a distinct abnormality. PMID:21709236

Shannon, Benjamin J; Raichle, Marcus E; Snyder, Abraham Z; Fair, Damien A; Mills, Kathryn L; Zhang, Dongyang; Bache, Kevin; Calhoun, Vince D; Nigg, Joel T; Nagel, Bonnie J; Stevens, Alexander A; Kiehl, Kent A

2011-07-01

240

Oscillation for higher order nonlinear ordinary differential equations with impulses  

Directory of Open Access Journals (Sweden)

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.

Chaolong Zhang

2006-02-01

 
 
 
 
241

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

Science.gov (United States)

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 performance on color-naming but not word-meaning trials of a Stroop task. In Studies 2 and 3, we found that higher levels of bladder pressure resulted in an increased ability to resist impulsive choices in monetary decision making. We found that inhibitory spillover effects are moderated by sensitivity of the Behavioral Inhibition System (Study 3) and can be induced by exogenous cues (Study 4). Implications for inhibition and impulse-control theories are discussed. PMID:21467548

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

2011-05-01

242

The effect of spinal manipulation impulse duration on spine neuromechanical responses  

Science.gov (United States)

Introduction: Spinal manipulation therapy (SMT) is characterized by specific kinetic and kinematic parameters that can be modulated. The purpose of this study is to investigate fundamental aspects of SMT dose-physiological response relation in humans by varying SMT impulse duration. Methods: Twenty healthy adults were subjected to four different SMT force-time profiles delivered by a servo-controlled linear actuator motor and differing in their impulse duration. EMG responses of the left and right thoracic paraspinal muscles (T6 and T8 levels) and vertebral displacements of T7 and T8 were evaluated for all SMT phases. Results: Significant differences in paraspinal EMG were observed during the “Thrust phase” and immediately after (“Post-SMT1”) (all T8 ps 0.05). Conclusion: Decreasing SMT impulse duration leads to a linear increase in EMG response of thoracic paraspinal during and following the SMT thrust.

Page, Isabelle; Nougarou, Francois; Dugas, Claude; Descarreaux, Martin

2014-01-01

243

Self-Reported Impulsivity, Rather than Sociosexuality, Predicts Women's Preferences for Masculine Features in Male Faces.  

Science.gov (United States)

Previous research has suggested that an individual's sociosexual orientation (i.e., their willingness to engage in sexual behavior outside of long-term relationships) may influence the qualities they find attractive in a potential mate. Results, however, have not been consistent and, moreover, studies have tended to draw from specific social groups. Here, we tested the relationship between sociosexuality and female's preferences for masculinity in male faces, using a diverse population. We furthermore investigated impulsivity alongside sociosexuality, as this trait has been suggested as a "root" cause of variation in sexual behavior (Cross, 2010) and thus may better explain variation in mate choice. Results showed a significant association between increases in both sociosexuality and two subcomponents of impulsivity and greater preferences for masculine male features. Regression analysis suggested that a subcomponent of impulsivity, namely lack of planning, was the primary determinant of preferences. We discuss the implications these results have for our understanding of female attraction to masculine features. PMID:24346865

Boothroyd, Lynda G; Brewer, Gayle

2014-07-01

244

ADHD-hyperactive/impulsive subtype in adults  

Directory of Open Access Journals (Sweden)

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.

Stephen V. Faraone

2010-01-01

245

Impulsive for life? The nature of long-term impulsivity in domestic dogs.  

Science.gov (United States)

Individual differences in impulsivity occur at a cognitive and/or behavioural level and are associated with differing life outcomes. However, there is a lack of empirical evidence to support the long-term stability of these characteristics in non-human animals. This study reports on the stability of convergent measures of impulsivity in domestic dogs assessed more than 6 years apart. Measures were (1) owner assessment by means of a questionnaire, the validated 'Dog Impulsivity Assessment Scale' (DIAS) and (2) dogs' performance in a delayed reward choice test. Dogs had 15-min free access to two food dispensers, one dispensing a piece of food immediately, the other dispensing three pieces after a delay, which increased by 1 s every other time the dogs sampled it. Maximum delay reached in this task reflects decision-making, or cognitive impulsivity, whereas the rate of extra presses on the delayed reward device during the delay can be considered as a measure of motor or behavioural impulsivity. DIAS scores were strongly and significantly correlated across years. The maximum delay reached in the behaviour test was also highly stable, whereas paw-pressing rate was uncorrelated between the years. These results demonstrate that cognitive but not motor impulsivity is highly consistent over time in dogs. PMID:24136014

Riemer, Stefanie; Mills, Daniel S; Wright, Hannah

2014-05-01

246

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

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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...

2013-01-01

247

Stability and Stabilization of Impulsive Stochastic Delay Difference Equations  

Directory of Open Access Journals (Sweden)

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.

Liming Wang

2010-01-01

248

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

Science.gov (United States)

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

Masse, Louis Philippe

249

LMFBR core flowering response to an impulse load  

International Nuclear Information System (INIS)

Some incidental situations like MFCI (Meeting Fuel Coolant Incident) may induce a core flowering and lead to consider impulse loads applied to LMFBR core. These highly dynamic loads are very different considering their spatial repartition and their frequency content from the seismic loads which have been deeply studied. Recently, tests have been performed on the LMFBR core mock-up RAPSODIE in order to validate the calculation methods for centered impulse load. These tests consist in injecting water quickly in the mock-up through a specific device replacing the core central assembly. The influence of the injection pressure and the influence of the injection axial position have been investigated. During the tests, the top displacements of some assemblies have been measured. The aim of this paper is first to present the experimental device and the test results. Then a non linear numerical model is described; this model includes the impact between subassemblies and is based on an homogenization method allowing to take into account with accuracy the fluid structure interaction. The comparisons between calculation results and test results will finally be presented

1993-08-15

250

Impulse control disorders in women with eating disorders.  

Science.gov (United States)

We compared symptom patterns, severity of illness, and comorbidity in individuals with eating disorders with and without impulse control disorders (ICD), and documented the temporal pattern of illness onset. Lifetime ICD were present in 16.6% of 709 women with a history of eating disorders. The most common syndromes were compulsive buying disorder and kleptomania. ICD occurred more in individuals with binge eating subtypes, and were associated with significantly greater use of laxatives, diuretics, appetite suppressants and fasting, and with greater body image disturbance, higher harm avoidance, neuroticism, cognitive impulsivity, and lower self-directedness. In addition, individuals with ICD were more likely to have obsessive-compulsive disorder, any anxiety disorder, specific phobia, depression, cluster B personality disorder, avoidant personality disorder, and to use psychoactive substances. Among those with ICD, 62% reported the ICD predated the eating disorder and 45% reported the onset of both disorders within the same 3-year window. The presence of a lifetime ICD appears to be limited to eating disorders marked by binge eating and to be associated with worse eating-related psychopathology, more pathological personality traits, and more frequent comorbid Axis I and II conditions. Untreated ICD may complicate recovery from eating disorders. PMID:17961717

Fernández-Aranda, Fernando; Pinheiro, Andréa Poyastro; Thornton, Laura M; Berrettini, Wade H; Crow, Scott; Fichter, Manfred M; Halmi, Katherine A; Kaplan, Allan S; Keel, Pamela; Mitchell, James; Rotondo, Alessandro; Strober, Michael; Woodside, D Blake; Kaye, Walter H; Bulik, Cynthia M

2008-01-15

251

Filament-driven impulsive Raman spectroscopy.  

Science.gov (United States)

Vibrational Raman spectroscopy is performed in the gas phase using a femtosecond laser pulse undergoing filamentation as an impulsive excitation source. The molecular coherence induced by the filamentary pulse is subsequently probed using a narrowband, sub-picosecond laser pulse to produce Raman spectra of gas phase species in a few tens of milliseconds (~10 laser shots). Pulse shortening with concomitant spectral broadening during filamentation results in a pulse that is both sufficiently short and of sufficient spectral power density to impulsively excite the highest energy ground state vibrations (up to 4158 cm(-1) corresponding to H(2)). Gas phase detection of chloroform, methylene chloride, cyclohexane, toluene, pentane, triethylamine, ammonia, nitromethane, and gasoline is performed. PMID:21977899

Odhner, Johanan H; McCole, Erin T; Levis, Robert J

2011-11-24

252

Design and construction of an impulse turbine  

Science.gov (United States)

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.

Hernández, E.

2013-11-01

253

[Impulse control behaviors associated with antiparkinsonian medications].  

Science.gov (United States)

In some patients, impulse control behaviours can be triggered by dopaminergic replacement therapy, particularly dopamine agonist drugs: hobbyism, punding (stereotyped behaviours), compulsive buying, binge eating disorder, pathological gamgling, hypersexuality, hedonistic homeostatic dysregulation syndrome ... The pathogenesis of these behaviours: is not well understood, but likely involves aberrant changes in the dopaminergic pathways that mediate motivation i.e., a dopaminergic "overdose" in meso-cortico-limbic circuits, An early diagnosis is difficult, but mandatory to prevent the occurrence of devastating familial, marital, professional, socio-economic, medical and medico-legal consequences. Their management is not yet well standardized. Patients and caregivers should be warned about impulse control behaviours before starting dopamine agonists and monitoring for such behaviours while on therapy is requested. PMID:23888568

Depierreux-Lahaye, F; Crémers, J; Skawiniak, E; Parmentier, E; Delvaux, V; Garraux, G

2013-01-01

254

Strength measurement of impulse compacted moulding sand  

Directory of Open Access Journals (Sweden)

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.

T. Mikulczy?ski

2011-01-01

255

Temporal shift from magnetoplasma resonance to cyclotron resonance of photo-carriers generated from 1s-exciton in cuprous oxide crystal  

Science.gov (United States)

We have established a method for time-resolved cyclotron resonance measurements using an electron spin resonance cavity with a temporal resolution 15 ns under photo-excitation in an undoped semiconductor, cuprous oxide. The observed photo-carriers are generated via long-lived 1s-excitons excited at the phonon assisted absorption edge below the yellow gap. This work focuses on the fast response that is within 80 ns after photo-excitation of high-density excitons. A shift of the photo-carriers from a magnetoplasma resonance to a cyclotron resonance, previously known as a steady resonance in highly doped semiconductors, is observed for the first time in the temporal domain. We successfully explain the real and imaginary parts of the transient microwave absorption using spectral simulations, taking account of the depolarization factors in two different sample shapes and configurations in the cavity.

Akimoto, I.; Torai, S.; Naka, N.; Shirai, M.

2012-11-01

256

Science of NHL Hockey: Force, Impulse & Collisions  

Science.gov (United States)

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.

Learn, Nbc

2010-10-07

257

FEM Analysis of Turgo Impulse Turbine Blade  

Directory of Open Access Journals (Sweden)

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

Sourabh KHURANA

2013-07-01

258

Acoustic radiation force impulse of the liver  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Acoustic radiation force impulse (ARFI) imaging is a new and promising ultrasound-based diagnostic technique that, evaluating the wave propagation speed, allows the assessment of the tissue stiffness. ARFI is implemented in the ultrasound scanner. By short-duration acoustic radiation forces (less than 1 ms), localized displacements are generated in a selected region of interest not requiring any external compression so reducing the operator dependency. The generated wave scan provides qualita...

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

2013-01-01

259

Modeling High Power Impulse Magnetron Sputtering Discharges  

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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...

2012-01-01

260

Impulse response measurement of ultrasonic transducers  

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Digital processing of acoustic signals introduces pulses to measurement of impedances and transfer functions of ultrasonic systems. Digital impulse measurements of electroacoustic transducers described in the paper are based on comparison between the Fourier transforms of the input signals and the responses of the ultrasonic systems. Measuring signals consisting of two separate parts have been used where the power piezoelectric transducer is the input part of the system. Similarly, the output...

Kadlec, F.

1994-01-01

 
 
 
 
261

Nonparametric estimation of generalized impulse response function  

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A local linear estimator of generalized impulse response (GIR) functions for nonlinear conditional heteroskedastic autoregressive processes is derived and shown to be asymptotically normal. A plug-in bandwidth is obtained that minimizes the asymptotical mean squared error of the GIR estimator. A local linear estimator for the conditional variance function is proposed which has simpler bias than the standard estimator. This is achieved by appropriately eliminating the conditional mean. Alterna...

2000-01-01

262

The Dirac distorted wave impulse approximation revisited  

International Nuclear Information System (INIS)

Recently, we have proposed a new interpretation of the successful Dirac approach to proton-nucleus elastic scattering, based on relativistic kinematics and the Lorentz-Lorenz correction. Here, we show that the Dirac distorted wave impulse approximation for low-lying collective states can be understood along the same lines. This confirms our view that relativistic effects are not the only possible explanation of the polarization data at intermediate energies. (orig.)

1986-01-01

263

Model dependence of the impulse approximation  

International Nuclear Information System (INIS)

We investigate the model dependence of the impulse approximation for proton-nucleus elastic scattering stemming from off-shell and non-local effects. A perturbative treatment allows a direct comparison between off-shell and relativistic effects. Off-shell effects are found to be significantly smaller and unable to account in a natural way for the needed repulsive central potential in the nuclear interior region at proton energies between 300 and 800 MeV. (orig.)

1991-01-01

264

Relativistic impulse approximation for nuclear inelastic scattering  

International Nuclear Information System (INIS)

The Relativistic Impulse Approximation (RIA) for proton-nucleus elastic and inelastic scattering is contrasted with its non-relativistic counterpart (the NRIA). Differences between the two approaches are examined with special emphasis on the nuclear convection current and its generalizations which may show signatures of strong relativistic nuclear potentials. A simple extension of the RIA to meson-nucleus scattering based on the linear, spin-zero Duffin-Kemmer wave equation is considered

1985-09-15

265

FEM Analysis of Turgo Impulse Turbine Blade  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

Khurana, Sourabh; Goel, Varun; Kumar, Anoop

2013-01-01

266

FEM Analysis of Turgo Impulse Turbine Blade  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present research work describes the development of Turgo turbine blades on Solid works software then 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 maximum stress at the root of blade suction side. 

Khurana, Sourabh; Goel, Varun; Kumar, Anoop

2013-01-01

267

Fundamentals of High Power Impulse Magnetron Sputtering  

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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...

Bo?hlmark, Johan

2006-01-01

268

Bending Wavelet for Flexural Impulse Response  

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The work addresses the definition of a wavelet that is adapted to analyse a flexural impulse response. The wavelet gives the opportunity to directly analyse the dispersion characteristics of a pulse. The aim is to localize a source or to measure material parameters. An overview of the mathematical properties of the wavelet is presented. An algorithm to extract the dispersion characteristics with the use of genetic algorithms is outlined. The application of the wavelet is sho...

Buessow, Richard

2006-01-01

269

A Study of Impulse Response System Identification  

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In system identification, different methods are often classified as parametric or non-parametric methods. For parametric methods, a parametric model of a system is considered and the model parameters are estimated. For non-parametric methods, no parametric model is used and the result of the identification is given as a curve or a function. One of the non-parametric methods is the impulse response analysis. This approach is dynamic simulation. This thesis introduces a new paradigm for dynamic...

Paluri, Suraj; Patluri, Sandeep

2007-01-01

270

Dynamic Properties of Impulse Measuring Systems  

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

Pedersen, A.; Lausen, P.

2009-01-01

271

Theory of 'crotchet' impulse component generation  

International Nuclear Information System (INIS)

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

2002-06-21

272

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.)

1982-01-01

273

Meson theoretical basis for Dirac impulse approximation  

International Nuclear Information System (INIS)

Basic features of proton-nucleus optical potentials for use in the Dirac equation are discussed. The original form of the Dirac impulse approximation follows from using Fermi covariants (scalar, vector, tensor, pseudoscalar, and axial vector) to extend physical NN amplitudes into operators in the full Dirac space. Overly large scalar and vector optical potentials are shown to follow at low energy in this case due to forcing pion exchange contributions to be pseudoscalar. The pair contributions to proton-nucleus scattering are much too large at low energy. A variant of the impulse approximation is developed by replacing pseudoscalar covariants by pseudovector ones. Much reduced scalar and vector strengths are obtained at low energy in the pseudovector case. The pair contributions are similarly reduced to reasonable values. However, the large differences between optical potentials based on pseudoscalar and pseudovector covariants are not controlled by physical NN scattering data. These differences represent a basic ambiguity in NN amplitudes when the only constraint is positive energy scattering data. Using a complete and unambiguous set of NN Lorentz invariant amplitudes obtained from a relativistic one-meson-exchange model, the scalar and vector optical potential strengths are found to be reasonably constant over the range of 50 to 1000 MeV of proton energy. The meson theory results for nuclear matter are found to be comparable to those obtained when the pseudoscalar covariant is replaced by the pseudovector covariant in the original impulse approximation

1985-01-01

274

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

1985-02-02

275

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

Directory of Open Access Journals (Sweden)

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

Mettman DJ

2014-03-01

276

Cannabinoid CB1 receptor activation mediates the opposing effects of amphetamine on impulsive action and impulsive choice.  

Science.gov (United States)

It is well known that acute challenges with psychostimulants such as amphetamine affect impulsive behavior. We here studied the pharmacology underlying the effects of amphetamine in two rat models of impulsivity, the 5-choice serial reaction time task (5-CSRTT) and the delayed reward task (DRT), providing measures of inhibitory control, an aspect of impulsive action, and impulsive choice, respectively. We focused on the role of cannabinoid CB1 receptor activation in amphetamine-induced impulsivity as there is evidence that acute challenges with psychostimulants activate the endogenous cannabinoid system, and CB1 receptor activity modulates impulsivity in both rodents and humans. Results showed that pretreatment with either the CB1 receptor antagonist/inverse agonist SR141716A or the neutral CB1 receptor antagonist O-2050 dose-dependently improved baseline inhibitory control in the 5-CSRTT. Moreover, both compounds similarly attenuated amphetamine-induced inhibitory control deficits, suggesting that CB1 receptor activation by endogenously released cannabinoids mediates this aspect of impulsive action. Direct CB1 receptor activation by ?9-Tetrahydrocannabinol (?9-THC) did, however, not affect inhibitory control. Although neither SR141716A nor O-2050 affected baseline impulsive choice in the DRT, both ligands completely prevented amphetamine-induced reductions in impulsive decision making, indicating that CB1 receptor activity may decrease this form of impulsivity. Indeed, acute ?9-THC was found to reduce impulsive choice in a CB1 receptor-dependent way. Together, these results indicate an important, though complex role for cannabinoid CB1 receptor activity in the regulation of impulsive action and impulsive choice as well as the opposite effects amphetamine has on both forms of impulsive behavior. PMID:22016780

Wiskerke, Joost; Stoop, Nicky; Schetters, Dustin; Schoffelmeer, Anton N M; Pattij, Tommy

2011-01-01

277

Perceived parental rejection mediates the influence of serotonin transporter gene (5-HTTLPR) polymorphisms on impulsivity in Japanese adults.  

Science.gov (United States)

This study examined (1) the interrelationships among 5-HTTLPR genotype, perceived parental rejection, and impulsivity, and (2) meditational models in which perceived paternal/maternal rejection mediates the relationship between the 5-HTTLPR genotype and impulsive behaviour. Participants included 403 adults (152 males and 252 females, mean age = 24.20) who provided genetic data and a set of the questionnaires (BIS11; Barratt Impulsiveness Scale-11 and EMBU; Egna Minnen av Bätraffande Uppfostran). Using SEM (Structural Equation Modeling), we evaluated 3 models for both direct and indirect relationships between 5-HTTLPR (5HTT) and Impulsivity (IMP), via maternal/fraternal rejection (MAT/FAT). In model 1, the direct path from 5HTT and IMP was not significant across the mother's and father's analysis. Models 2 and 3 assessed the indirect influence of 5HTT on IMP through MOT/FAT. The paths of models 2 and 3 were all significant and showed a good fit between the hypothesized model and data. Furthermore, the effects of the 5-HTTLPR genotype on impulsiveness in this Japanese sample were particularly accounted for by perceived rejection from the mother or father. The effects from the parents appeared to be robust especially among males. These results may help elucidate the specific pathways of risk in relation to genetic and environment influences on impulsive phenotypes. PMID:23112823

Nishikawa, Saori; Nishitani, Shota; Fujisawa, Takashi X; Noborimoto, Ippei; Kitahara, Takayuki; Takamura, Tsunehiko; Shinohara, Kazuyuki

2012-01-01

278

Perceived Parental Rejection Mediates the Influence of Serotonin Transporter Gene (5-HTTLPR) Polymorphisms on Impulsivity in Japanese Adults  

Science.gov (United States)

This study examined (1) the interrelationships among 5-HTTLPR genotype, perceived parental rejection, and impulsivity, and (2) meditational models in which perceived paternal/maternal rejection mediates the relationship between the 5-HTTLPR genotype and impulsive behaviour. Participants included 403 adults (152 males and 252 females, mean age?=?24.20) who provided genetic data and a set of the questionnaires (BIS11; Barratt Impulsiveness Scale-11 and EMBU; Egna Minnen av Bätraffande Uppfostran). Using SEM (Structural Equation Modeling), we evaluated 3 models for both direct and indirect relationships between 5-HTTLPR (5HTT) and Impulsivity (IMP), via maternal/fraternal rejection (MAT/FAT). In model 1, the direct path from 5HTT and IMP was not significant across the mother’s and father’s analysis. Models 2 and 3 assessed the indirect influence of 5HTT on IMP through MOT/FAT. The paths of models 2 and 3 were all significant and showed a good fit between the hypothesized model and data. Furthermore, the effects of the 5-HTTLPR genotype on impulsiveness in this Japanese sample were particularly accounted for by perceived rejection from the mother or father. The effects from the parents appeared to be robust especially among males. These results may help elucidate the specific pathways of risk in relation to genetic and environment influences on impulsive phenotypes.

Nishikawa, Saori; Nishitani, Shota; Fujisawa, Takashi X.; Noborimoto, Ippei; Kitahara, Takayuki; Takamura, Tsunehiko; Shinohara, Kazuyuki

2012-01-01

279

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

1992-01-01

280

Synthesis of Room Impulse Responses for Variable Source Characteristics  

Directory of Open Access Journals (Sweden)

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.

M. Kunkemoeller

2011-01-01

 
 
 
 
281

Collision of impulsive gravitational waves followed by dust clouds  

International Nuclear Information System (INIS)

The evolution of a space-time containing two colliding plane impulsive gravitational waves each of whose leading edges is followed by a distribution of null dust is determined. The conditions on the Ricci tensor that ensure that the evolution of such a space-time is unambiguous are determined. These are the same as those that apply in the planar case. The equations of motion of the medium contained in the region of interaction of the dust clouds are determined. These equations determine the change in energy density of each dust cloud as the interaction proceeds and involve the functions whose specifications ensure that the evolution of the space-time is unambiguous

1988-01-01

282

Study of impulse control disorders among women presenting nicotine dependence.  

Science.gov (United States)

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

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

2006-01-01

283

The Relationship between Impulsive and Reflective Problem Solving Behavior  

Directory of Open Access Journals (Sweden)

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

Vahid Nejati

2012-03-01

284

Influence of demographic and individual difference factors on impulse buying  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 re...

2010-01-01

285

Impulsivity in Animal Models for Drug Abuse Disorders  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Jentsch, J. David

2008-01-01

286

Impulsive consumption and reflexive thought: Nudging ethical consumer behavior  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Lades, Leonhard K.

2012-01-01

287

Dynamic Measurement of Room Impulse Responses using a Moving Microphone  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A novel technique for the recording of large sets of room impulse responses or head-related transfer functions is presented. The technique uses a microphone or a loudspeaker moving with constant speed. Given a setup (e.g. length of the room impulse response), a careful choice of the recording parameters (excitation signal, speed of movement) is shown to lead to the reconstruction of all impulse responses along the trajectory. In the case of moving element along a circle, the maximal a...

2007-01-01

288

Electrical Sterilization of Juice by Discharged HV Impulse Waveform  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the sterilization system by using HV impulse waveform, apple juice was sterilized with HV discharged oscillatory decay waveform. The optimal condition of impulse waveform for electrical sterilization has presented the excellent condition at 40kV cm?1, 4mH and over. The characteristics of this waveform shows oscillatory decay waveform with multiple pulses. And this impulse waveform was more effective to kill S. Cervisiae than exponential decay waveform. S. Cervisia...

Lee, Hee K.

2006-01-01

289

Effects of Pramipexole on Impulsive Choice in Male Wistar Rats  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Clinical reports, primarily with Parkinson's disease patients, note an association between the prescribed use of pramipexole (and other direct-acting dopamine agonist medications) and impulse control disorders, particularly pathological gambling. Two experiments examined the effects of acute pramipexole on rats' impulsive choices where impulsivity was defined as selecting a smaller–sooner over a larger–later food reward. In Experiment 1, pramipexole (0.1 to 0.3 mg/kg) significantly...

2010-01-01

290

Effects of Pramipexole on Impulsive Choice in Male Wistar Rats  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Clinical reports, primarily with Parkinson’s patients, note an association between the prescribed use of pramipexole (and other direct-acting dopamine agonist medications) and impulse control disorders, particularly pathological gambling. Two experiments examined the effects of acute pramipexole on rats’ impulsive choices where impulsivity was defined as selecting a smaller-sooner over a larger-later food reward. In Experiment 1, pramipexole (0.1 to 0.3 mg/kg) significantly increased impu...

2010-01-01

291

Virtual Shopping and Impulse Purchasing Strengths and Weaknesses in Pakistan  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2011-01-01

292

Dimensions of impulsivity among heavy drinkers, smokers, and heavy drinking smokers: singular and combined effects.  

Science.gov (United States)

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 initiation of drug use, continued use despite negative consequences, and potential to relapse. This study used three behavioral tasks to measure risky decision-making (balloon analog risk test; BART), response inhibition (stop signal task; SST), and delay reward discounting (delay discounting task; DDT). This study advances research on impulsivity and substance use by parsing out the various components of impulsivity and examining them across three groups, heavy drinkers only (HD) (N=107), smokers only (S) (N=67), and heavy drinking smokers (HDS) (N=213). Participants completed questionnaires, interviews, and neurocognitive tasks including the SST, BART, and DDT. Analyses supported an additive effect of alcohol and nicotine use in delay reward discounting. Heavy drinking smokers displayed steeper delay discounting of small rewards than did smokers only (p<.05) and heavy drinkers only (p<.05). This additive effect of smoking and drinking was not observed for risky decision-making and response inhibition, suggesting specificity of the effects for delay reward discounting. These findings indicate that those who both drink heavily and smoke cigarettes daily have increased delay reward discounting, than those in the S and HD groups. Future studies should examine these constructs longitudinally, as well as incorporate genetic and/or a neuroimaging component to these group comparisons in order to ascertain the biological bases of these behavioral findings. PMID:22445419

Moallem, Nathasha R; Ray, Lara A

2012-07-01

293

Analyses and Modeling Impulse Noise Generated by Household Appliances  

Directory of Open Access Journals (Sweden)

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.

Jaroslav Krejci

2014-01-01

294

Adaptive Impulsive Outer Synchronization Between Drive-Response Dynamical Networks  

Science.gov (United States)

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.

Wu, Zhao-Yan

2014-05-01

295

Impulsive control of a financial model [rapid communication  

Science.gov (United States)

In this Letter, several new theorems on the stability of impulsive control systems are presented. These theorem are then used to find the conditions under which an advertising strategy can be asymptotically control to the equilibrium point by using impulsive control. Given the parameters of the financial model and the impulsive control law, an estimation of the upper bound of the impulse interval is given, i.e., number of advert can been decreased (i.e., can decrease cost) for to obtain the equivalent advertising effect.The result is illustrated to be efficient through a numerical example.

Sun, Jitao; Qiao, Fei; Wu, Qidi

2005-02-01

296

Diagnostics and Impulse Performance of Laser-Ablative Propulsion  

International Nuclear Information System (INIS)

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

2008-04-28

297

Impulsive control and synchronization of a new chaotic system  

International Nuclear Information System (INIS)

This Letter derives some sufficient conditions for the stabilization and synchronization of the new chaotic system proposed by [G.Y. Qi, et al., Physica A 352 (2005) 295] via an impulsive method. Some new and less conservative criteria for the global exponential stability and asymptotical stability of impulsively controlled new chaotic system are obtained with varying impulsive intervals. In particular, some simple and easily verified criteria are established with equivalent impulsive intervals. An illustrative example is finally included to visualize the effectiveness and feasibility of the developed methods

2008-01-28

298

Impulsive control and synchronization of unified chaotic system  

International Nuclear Information System (INIS)

We investigate the issue on impulsive control and synchronization of the unified chaotic system, which unifies both the Lorenz system and the Chen system. Some new and general conditions with varying impulsive distances are obtained to guarantee the impulsive control and synchronization global asymptotical stable. Especially, in the case of equal impulsive distances, some simple and easily verified sufficient conditions are derived for stabilizing and synchronizing the unified chaotic system. An illustrative example, along with computer simulation results, is finally included to visualize the effectiveness and feasibility of the developed methods

2004-05-01

299

Impulsive and compulsive behaviors in Parkinson's disease.  

Science.gov (United States)

Antiparkinson therapy can be the primary cause of a range of nonmotor symptoms that include a set of complex disinhibitory psychomotor pathologies and are linked by their repetitive, reward or incentive-based natures. These behaviors relate to aberrant or excessive dopamine receptor stimulation and encompass impulse control disorders (ICDs), punding, and the dopamine dysregulation syndrome (DDS). Common ICDs include pathological gambling, hypersexuality, compulsive eating, and compulsive buying. This review focuses on the phenomenology, epidemiology, and methods to identify and rate these disorders. The management of dopaminergic drug-related compulsive behaviors is discussed in the light of the current understanding of the neurobiological substrate of these disorders. PMID:19526584

Evans, Andrew H; Strafella, Antonio P; Weintraub, Daniel; Stacy, Mark

2009-08-15

300

Dynamical mechanical systems under random impulses  

CERN Multimedia

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

Iwankiewicz, R

1995-01-01

 
 
 
 
301

On the completeness of impulsive gravitational waves  

CERN Document Server

We consider the impulsive limit of a class of space-times generalizing pp-waves that are given in the form $M=N\\times\\mathbb{R}^2_1$ where $(N,h)$ is a Riemannian manifold of arbitrary dimension and $M$ carries the line element $ds^2=dh^2+ 2dudv+f(x)\\delta(u)du^2$ with $dh^2$ the line element of $N$ and $\\delta$ the Dirac measure. We prove a completeness result for these space-times.

Sämann, Clemens

2012-01-01

302

High power impulse magnetron sputtering discharge  

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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...

2012-01-01

303

Mechanism of impulse compacting of moulding sands  

Directory of Open Access Journals (Sweden)

Full Text Available A mathematicat 3D modcl or impulsc compaction process. developed in the Basic Automalion Laboratory of thc Instimtc oFProductionEngineering and Automation is prcscnted. Experimental and simulation rcscarch analysis allowcd to dctcrminc mechanism or impulsecompacting of moulding sands. Mcchanisrn and dynamics of this proccss cvaluatcd on t hc grounds of relationships p, =I(d rrprcscnringtime functions of total prcssurc in thc sand 1aytrs Pocatcd at different heights of thc compactcd sand column. Presented expcrimcntal andsimrilation scscarch provcd that dcvclopcd 3D mathematical model of impulse compaction proccss of moulding sand describes [his proccssin dctail.

T. MikuIczy?ski

2008-03-01

304

A skin friction gauge for impulsive flows  

Science.gov (United States)

A new skin friction gauge has been designed for use in impulsive facilities. The gauge was tested in the T4 free piston shock tunnel, at the University of Queensland, using a 1.5 m long plate that formed one of the inner walls of a rectangular duct. The test gas was fair and the test section free stream flow had a stagnation enthalpy of 4.7 MJ/kg. Measurements were conducted in a laminar and turbulent boundary layer. The measurements compared well with laminar and turbulent analytical theory.

Goyne, C. P.; Paull, A.; Stalker, R. J.

305

Impulsive stabilization of linear delay differential equations  

CERN Document Server

The paper is concerned with stabilization of a scalar delay differention equation {\\dot x}(t) - \\sum_{k=1}^m A_k(t)x[h_k(t)] = 0,~t\\geq 0,~ x(\\xi)=\\varphi (\\xi), \\xi <0, by introducing impulses in certain moments of time x(\\tau_j) = B_j x(\\tau_j -0), ~j=1,2, \\dots ~. Explicit stability results are presented both for the equation with positive coefficients and for the equation with A_k being of arbitrary sign.

Berezansky, L; Berezansky, L; Braverman, E

1995-01-01

306

Polarization effect in impulsive rotational Raman scattering  

International Nuclear Information System (INIS)

We theoretically study rotational Raman coherence excited impulsively in a hydrogen-gas-filled hollow fiber by an fs pump pulse with an arbitrary ellipticity. The results of our simulations based on a rotationally invariant formalism show that the use of an elliptically polarized pulse leads to more efficient phonon excitation than that of a linearly or circularly polarized one. The phonon amplitude dramatically depends both on ellipticity and propagation distance. The passage of a probe pulse in this excited media leads to the generation of high-order Raman sidebands in the pulse

2002-09-01

307

Investigation of gas discharge impulse image intensifiers  

International Nuclear Information System (INIS)

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 ?1010. 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, CO2, iC4H10 and their mixtures in the 50-760 Torr pressure range have been investigated. The best working gas for the GDIII is Ne+(?0.1%)iC4H10 mixture having an electron output factor up to 0.45

1999-08-21

308

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

Science.gov (United States)

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

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

2006-06-01

309

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

Science.gov (United States)

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

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

2006-12-01

310

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)

1982-06-04

311

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

2009-01-01

312

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigate the use of greedy sparse approximation for facilitating the time-domain analysis of room impulse responses (RIRs), specifically locating the times and amplitudes of arrivals to not long after the upper bound of the ``mixing time,'' i.e., the time after which there exists in theory the same number of sound rays per unit volume throughout the room. We compare the performance of two methods of greedy sparse approximation --- matching pursuit (MP) and orthogonal MP (OMP) --- for es...

2012-01-01

313

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigate the use of greedy sparse approximation for facilitating the time-domain analysis of room impulse responses (RIRs), specifically locating the times and amplitudes of arrivals to not long after the upper bound of the ``mixing time,'' i.e., the time after which there exists in theory the same number of sound rays per unit volume throughout the room. We compare the performance of two methods of greedy sparse approximation --- matching pursuit (MP) and orthogonal MP (OMP) --- for es...

2010-01-01

314

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

Science.gov (United States)

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.

Whitmarsh, C. L., Jr.

1972-01-01

315

Few body impulse and fixed scatterer approximations for high energy scattering  

International Nuclear Information System (INIS)

The elastic scattering differential cross section is calculated for proton scattering from 6He at 717 MeV, using single scattering terms of the multiple scattering expansion of the total transition amplitude (MST). We analyse the effects of different scattering frameworks, specifically the factorized impulse approximation (FIA) and the fixed scatterer (adiabatic) approximation (FSA) and the uncertainties associated with the use different structure models

2006-05-29

316

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of the modern communication technologies is an immersive experience. One of the applications that should provide the feeling of being together and sharing the same environment during the communication process is BEAMING. The goal of this paper is to improve audible spatial impression utilizing correct acoustical properties of the specific environments. Binaural room impulse response (BRIR) synthesis represents one of the main tasks in the binaural auralization. When the BRIRs are simu...

2011-01-01

317

Magneto-plasma waveguide  

Science.gov (United States)

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

Hur, Min Sup; Wurtele, Jonathan

2003-10-01

318

Drug-induced impulse control disorders in Parkinson's disease.  

Science.gov (United States)

Dopamine replacement treatment with excessive or aberrant dopamine receptor stimulation can cause behavioral disturbances in Parkinson's disease, comprising dopamine dysregulation syndrome, punding, and impulse control disorders. Common impulse control disorders are compulsive buying, pathological gambling, binge eating, hypersexuality, and compulsive reckless driving. PMID:21560063

Reiff, J; Jost, W H

2011-05-01

319

Asymptotic stability of competitive systems with delays and impulsive perturbations  

Science.gov (United States)

A general impulsive nonautonomous Lotka-Volterra system of integro-differential equations with infinite delay is considered. The impulses are realized at fixed moments of time. Sufficient conditions for uniform stability and asymptotic stability of solutions are investigated. The main results are obtained by using the comparison principle and the Lyapunov method.

Ahmad, Shair; Stamova, Ivanka M.

2007-10-01

320

Impulsive integral equations in Banach spaces and applications  

Directory of Open Access Journals (Sweden)

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

Dajun Guo

1992-01-01

 
 
 
 
321

Asymptotic behavior of second-order impulsive differential equations  

Directory of Open Access Journals (Sweden)

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.

Haifeng Liu

2011-02-01

322

Oscillation of solutions to impulsive dynamic equations on time scales  

Directory of Open Access Journals (Sweden)

Full Text Available In this article, we study the oscillation of second order impulsive dynamic equations on time scales. The effect of the moments of impulse are fixed. Using Riccati transformation techniques, we obtain some conditions for the oscillation of all solutions

Qiaoluan Li

2009-09-01

323

Characteristic exponents of impulsive differential equations in a Banach space  

International Nuclear Information System (INIS)

The notion of general exponent of impulsive homogeneous differential equations is defined. A formula for the solution of impulsive nonhomogeneous differential equations is obtained and is used to establish a dependence between the existence of bounded solutions of such equations and the general exponent of the respective homogeneous equation

1988-01-01

324

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

2007-05-01

325

Impulsive integral equations in Banach spaces and applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

1992-01-01

326

A new nonlinear impulsive delay differential inequality and its applications  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract In this article, a new nonlinear impulsive delay differential inequality is established, which can be applied in the dynamical analysis of nonlinear systems to improve many extant results. Using the inequality, we obtain some sufficient conditions to guarantee the exponential stability of nonlinear impulsive functional differential equations. Two examples are given to illustrate the effectiveness and advantages of our results.

Wang Huali

2011-01-01

327

Impulsive Control and Synchronization of Rössler Chaotic System  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, synchronization between two Rössler Chaotic Systems with impulsively controlling is established by using the criteria on uniform equi-boundedness and equi-Lagrange stability for impulsive systems. After several theoretical derivations, some simulation results are given to demonstrate our results.

Yan Yan

2013-05-01

328

Impulsivity in internet addiction: a comparison with pathological gambling.  

Science.gov (United States)

Internet addiction has been considered to be associated with poor impulse control. The aim of this study is to compare the trait impulsivity of those suffering from Internet addiction with that of individuals suffering from pathological gambling. Twenty-seven patients diagnosed with Internet addiction (age: 24.78±4.37 years), 27 patients diagnosed with pathological gambling (age: 25.67±3.97 years), and 27 healthy controls (age: 25.33±2.79 years) were enrolled in this study. All patients were men seeking treatment. Trait impulsivity and the severity of the Internet addiction and pathological gambling were measured by the Barratt Impulsiveness Scale-11, the Young's Internet Addiction Test, and the South Oaks Gambling Screen, respectively. The Beck Depression Inventory and the Beck Anxiety Inventory were also administered to all subjects. Our results show that those suffering from Internet addiction showed increased levels of trait impulsivity which were comparable to those of patients diagnosed with pathological gambling. Additionally, the severity of Internet addiction was positively correlated with the level of trait impulsivity in patients with Internet addiction. These results state that Internet addiction can be conceptualized as an impulse control disorder and that trait impulsivity is a marker for vulnerability to Internet addiction. PMID:22663306

Lee, Hae Woo; Choi, Jung-Seok; Shin, Young-Chul; Lee, Jun-Young; Jung, Hee Yeon; Kwon, Jun Soo

2012-07-01

329

Impulsive Control for Fractional-Order Chaotic Systems  

International Nuclear Information System (INIS)

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

2008-08-01

330

Virtual Shopping and Impulse Purchasing Strengths and Weaknesses in Pakistan  

Directory of Open Access Journals (Sweden)

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.

Muhammad Ali Hussain

2011-11-01

331

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

DEFF Research Database (Denmark)

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.

Callesen, Mette Buhl; Scheel-Krüger, Jørgen

2013-01-01

332

Second method of Lyapunov for stability of linear impulsive differential-difference equations with variable impulsive perturbations  

Directory of Open Access Journals (Sweden)

Full Text Available The present work is devoted to the study of stability of the zero solution to linear impulsive differential-difference equations with variable impulsive perturbations. With the aid of piecewise continuous auxiliary functions, which are generalizations of the classical Lyapunov's functions, sufficient conditions are found for the uniform stability and uniform asymptotical stability of the zero solution to equations under consideration.

D. D. Bainov

1998-01-01

333

Impulse control disorders in obese patients.  

Science.gov (United States)

The aim of this study was to determine the prevalence of impulse control disorders (ICDs) in morbidly obese individuals. One hundred bariatric surgery candidates were examined using a module of the Structured Clinical Interview for DSM-IV that has been developed for ICDs. Nineteen per cent suffered from at least one current ICD and 27% met the criteria for any lifetime ICD, most frequently skin picking (current, 8%; lifetime, 9%), compulsive buying (current 6%, lifetime 8%), and intermittent explosive disorder (current, 5%; lifetime, 10%). Patients with regular binge eating (N?=?25) reported significantly more often a history of at least one ICD compared with those without binge eating. The results indicate a high prevalence of ICDs among morbidly obese prebariatric surgery patients that are related to regular binge eating. PMID:22367789

Schmidt, Frauke; Körber, Stephanie; de Zwaan, Martina; Müller, Astrid

2012-05-01

334

On coating adhesion during impulse plasma deposition  

Science.gov (United States)

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.

Nowakowska-Langier, Katarzyna; Zdunek, Krzysztof; Chodun, Rafal; Okrasa, Sebastian; Kwiatkowski, Roch; Malinowski, Karol; Sk?adnik-Sadowska, Elzbieta; Sadowski, Marek J.

2014-05-01

335

Impulsive electron acceleration by Gravitational Waves  

CERN Multimedia

We investigate the non-linear interaction of a strong Gravitational Wave with the plasma during the collapse of a massive magnetized star to form a black hole, or during the merging of neutron star binaries (central engine). We found that under certain conditions this coupling may result in an efficient energy space diffusion of particles. We suggest that the atmosphere created around the central engine is filled with 3-D magnetic neutral sheets (magnetic nulls). We demonstrate that the passage of strong pulses of Gravitational Waves through the magnetic neutral sheets accelerates electrons to very high energies. Superposition of many such short lived accelerators, embedded inside a turbulent plasma, may be the source for the observed impulsive short lived bursts. We conclude that in several astrophysical events, gravitational pulses may accelerate the tail of the ambient plasma to very high energies and become the driver for many types of astrophysical bursts.

Vlahos, L; Papadopoulos, D B; Vlahos, Loukas; Voyatzis, George; Papadopoulos, Demetrios

2004-01-01

336

SAR impulse response with residual chirps.  

Energy Technology Data Exchange (ETDEWEB)

A Linear Frequency-Modulated (LFM) chirp is a function with unit amplitude and quadratic phase characteristic. In a focused Synthetic Aperture Radar (SAR) image, a residual chirp is undesired for targets of interest, as it coarsens the manifested resolution. However, for undesired spurious signals, a residual chirp is often advantageous because it spreads the energy and thereby diminishes its peak value. In either case, a good understanding of the effects of a residual LFM chirp on a SAR Impulse Response (IPR) is required to facilitate system analysis and design. This report presents an analysis of the effects of a residual chirp on the IPR. As reference, there is a rich body of publications on various aspects of LFM chirps. A quick search reveals a plethora of articles, going back to the early 1950s. We mention here purely as trivia one of the earlier analysis papers on this waveform by Klauder, et al.

Doerry, Armin Walter

2009-06-01

337

Impulsive ion acceleration in earth's outer magnetosphere  

International Nuclear Information System (INIS)

Considerable observational evidence is found that ions are accelerated to high energies in the outer magnetosphere during geomagnetic disturbances. The acceleration often appears to be quite impulsive causing temporally brief (10's of seconds), very intense bursts of ions in the distant plasma sheet as well as in the near-tail region. These ion bursts extend in energy from 10's of keV to over 1 MeV and are closely associated with substorm expansive phase onsets. Although the very energetic ions are not of dominant importance for magnetotail plasma dynamics, they serve as an important tracer population. Their absolute intensity and brief temporal appearance bespeaks a strong and rapid acceleration process in the near-tail, very probably involving large induced electric fields substantially greater than those associated with cross-tail potential drops. Subsequent to their impulsive acceleration, these ions are injected into the outer trapping regions forming ion ''drift echo'' events, as well as streaming tailward away from their acceleration site in the near-earth plasma sheet. Most auroral ion acceleration processes occur (or are greatly enhanced) during the time that these global magnetospheric events are occurring in the magnetotail. A qualitative model relating energetic ion populations to near-tail magnetic reconnection at substorm onset followed by global redistribution is quite successful in explaining the primary observational features. Recent measurements of the elemental composition and charge-states have proven valuable for showing the source (solar wind or ionosphere) of the original plasma population from which the ions were accelerated

1985-06-03

338

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=t_n, n=0, 1, 2, ..., upon which quantum fields satisfy Dirichlet boundary conditions, with the associated Casimir effect, in a functional Schroedinger picture. 10 refs

1992-01-01

339

Do facets of self-reported impulsivity predict decision-making under ambiguity and risk? Evidence from a community sample.  

Science.gov (United States)

We investigated the links among decision-making assessed by the Iowa Gambling Task (IGT) and the Game of Dice Task (GDT), and the four facets of impulsivity (urgency, lack of premeditation, lack of perseverance, and sensation seeking, UPPS) proposed by Whiteside and Lynam (2001) in a sample of 107 healthy volunteers. Hierarchical regressions controlling for age and gender indicated that sensation seeking and urgency were linked to disadvantageous decisions on the GDT while no association was found between IGT performance and the UPPS. Sensation seeking and urgency facets of impulsivity are related in healthy individuals, to decision-making processes where potential consequences of different options and their subsequent probabilities rely on explicit information. In healthy controls, there is little overlap between decision-making influenced by both implicit and explicit information and impulsivity as measured by the UPPS. These findings add evidence to the notion that self-reported trait impulsivity is associated with the decision making process. Decisions made under risk seemed to be differentially associated with specific facets of impulsivity. PMID:21784534

Bayard, Sophie; Raffard, Stéphane; Gely-Nargeot, Marie-Christine

2011-12-30

340

Complex Dynamics of an Impulsive Control System in which Predator Species Share a Common Prey  

Science.gov (United States)

In an ecosystem, multiple predator species often share a common prey and the interactions between the predators are neutral. In view of this fact, we propose a three-species prey-predator system with the functional responses and impulsive controls to model the process of pest management. It is proved that the system has a locally stable pest-eradication periodic solution under the assumption that the impulsive period is less than some critical value. In particular, two single control strategies (biological control alone or chemical control alone) are proposed. Finally, we compare three pest control strategies and find that if we choose narrow-spectrum pesticides that are targeted to a specific pest’s life cycle to kill the pest, then the combined strategy is preferable. Numerical results show that our system has complex dynamics including period-doubling bifurcation, quasi-periodic oscillation, chaos, intermittency and crises.

Pei, Yongzhen; Liu, Shaoying; Li, Changguo

2009-06-01

 
 
 
 
341

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

Energy Technology Data Exchange (ETDEWEB)

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

Liu Bing [Department of Mathematics, Anshan Normal University, Anshan 114005, Liaoning (China) and Department of Mathematics, Xinjiang University, Urumqi 830046, Xinjiang (China)]. E-mail: liubing529@126.com; Teng Zhidong [Department of Mathematics, Xinjiang University, Urumqi 830046, Xinjiang (China); Liu Wanbo [Senior Middle School of Anshan Steel-Iron Company, Anshan 114034, Liaoning (China)

2007-01-15

342

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

International Nuclear Information System (INIS)

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

2007-01-01

343

Determination of poles and zeroes using SAVOSIM for digital impulse-shaping  

International Nuclear Information System (INIS)

Digital impulse pulse-shaping can be used to correct the pile-up for pulse-height (Energy) analyzer because of its fast processing speed. In this initial work on digital impulse pulse-shaping, a study is made on the input signals obtained from combination of preamplifier and prefilter of nuclear instrumentation with specific and general transfer function. Three types of pulses that are commonly produced by a nuclear detection preamplifier and prefilter are used for this application. For the determination of zeros and poles in z-transform, the summation of absolute value of output signal is minimum (SAVOSIM) method is used. Simulations for this type of signal are carried out using the MATLAB software and the TMS320C6701 evaluation module and the results are presented in this paper. Initial results show that the method can be expanded to design and develop for a nuclear spectroscopy based on digital signal processor. (Author)

2002-10-15

344

Tunnel ionization of hydrogen atom in laser impulse of short and ultrashort duration  

International Nuclear Information System (INIS)

By means of direct numerical integration of the Schroedinger nonstationary equation one investigates into hydrogen atom ionization in a low-frequency linearly polarized electromagnetic field. One compares data obtained for ionization different conditions and for different initial atomic states with the Keldysh and the Perelomov-Popov-Terentiev (PPT) theories. One specified application fields of a quasi-static model of the tunnel ionization and of the PPT theory based on intensity and frequency of laser radiation. One discusses peculiar features of tunnel ionization of the excited 2s- and 2p-states. One studied the specific nature of hydrogen atom ionization in an ultrashort laser impulse (impulse duration is of the order of one optical cycle)

2006-01-01

345

Attenuation of high-level impulses by earmuffs.  

Science.gov (United States)

Attenuation of high-level acoustic impulses (noise reduction) by various types of earmuffs was measured using a laboratory source of type A impulses and an artificial test fixture compatible with the ISO 4869-3 standard. The measurements were made for impulses of peak sound-pressure levels (SPLs) from 150 to 170 dB. The rise time and A duration of the impulses depended on their SPL and were within a range of 12-400 mus (rise time) and 0.4-1.1 ms (A duration). The results showed that earmuff peak level attenuation increases by about 10 dB when the impulse's rise time and the A duration are reduced. The results also demonstrated that the signals under the earmuff cup have a longer rise and A duration than the original impulses recorded outside the earmuff. Results of the measurements were used to check the validity of various hearing damage risk criteria that specify the maximum permissible exposure to impulse noise. The present data lead to the conclusion that procedures in which hearing damage risk is assessed only from signal attenuation, without taking into consideration changes in the signal waveform under the earmuff, tend to underestimate the risk of hearing damage. PMID:17902846

Zera, Jan; Mlynski, Rafal

2007-10-01

346

Method of reducing impulsive noise in electromagnetic geophysical data  

Energy Technology Data Exchange (ETDEWEB)

This patent describes a method of reducing impulsive noise in electromagnetic geophysical data. It comprises: providing receiving antenna means for receiving an electromagnetic signal. The receiving antenna means receiving impulsive noise; providing noise sensor means for receiving the impulsive noise and placing the noise sensor means so as to receive the impulsive noise that is received by the receiving antenna means and so as to minimize the reception of the electromagnetic signal; simultaneously receiving the electromagnetic signal with the receiving antenna means so as to create a signal record and receiving the impulsive noise with the noise sensor means so as to create a noise record; examining the noise record for occurrences of the impulsive noise by comparing the noise record with a threshold noise value and identifying those instances of time in which the noise record exceeds the threshold; removing those portions of the signal record which are simultaneous with the identified instances in which the noise records exceeds the threshold, wherein the signal record has reduced impulsive noise.

Spies, B.R.

1990-07-31

347

Stability of Impulsive Differential Equation with any Time Delay  

Directory of Open Access Journals (Sweden)

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.

Sanjay K. Srivastava

2013-03-01

348

Impulsivity and prefrontal hypometabolism in borderline personality disorder.  

Science.gov (United States)

Prefrontal hypoperfusion and decreased glucose uptake in the prefrontal cortex (PFC) are found in violent criminal offenders, murderers and aggressive psychiatric patients. These abnormalities may be independent of diagnosis and associated with impulsive-aggression as a personality trait. Impulsive-aggression is a clinical characteristic of borderline personality disorder (BPD) where it is associated with assaultive and suicidal behaviors. We conducted FDG-PET studies in 13 non-depressed, impulsive female subjects with BPD and 9 healthy controls to look for abnormalities in glucose metabolism in areas of the PFC associated with regulation of impulsive behavior. Statistical Parametric Mapping-99 (SPM99) was used to analyze the PET data with Hamilton depression scores as covariate. Significant reductions in FDG uptake in BPD subjects relative to healthy controls were found bilaterally in medial orbital frontal cortex, including Brodmann's areas 9, 10 and 11. There were no significant areas of increased uptake in BPD subjects compared to control subjects. Covarying for measures of impulsivity or impulsive-aggression rendered insignificant the differences between groups. Decreased glucose uptake in medial orbital frontal cortex may be associated with diminished regulation of impulsive behavior in BPD. PMID:12928103

Soloff, Paul H; Meltzer, Carolyn Cidis; Becker, Carl; Greer, Phil J; Kelly, Thomas M; Constantine, Doreen

2003-07-30

349

Impulsivity modulates performance under response uncertainty in a reaching task.  

Science.gov (United States)

We sought to explore the interaction of the impulsivity trait with response uncertainty. To this end, we used a reaching task (Pellizzer and Hedges in Exp Brain Res 150:276-289, 2003) where a motor response direction was cued at different levels of uncertainty (1 cue, i.e., no uncertainty, 2 cues or 3 cues). Data from 95 healthy adults (54 F, 41 M) were analysed. Impulsivity was measured using the Barratt Impulsiveness Scale version 11 (BIS-11). Behavioral 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 generalised additive mixed models. 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 versus low impulsives in the high uncertainty (3 cue) condition. In addition, there was a significant early error speed-accuracy trade-off for women, primarily in low uncertainty and a 'reverse' speed-accuracy trade-off for men in high uncertainty. These results extend those of past studies of impulsivity which help define it as a behavioural trait that modulates speed versus accuracy response styles depending on environmental constraints and highlight once more the importance of gender in the interplay of personality and behaviour. PMID:23239199

Tzagarakis, C; Pellizzer, G; Rogers, R D

2013-03-01

350

Near field impulsive source localization in a noisy environment  

Science.gov (United States)

When a machine has faults in its rotating parts, it normally generates a periodic vibration or acoustic signals. These signals are often periodic but impulsive. This paper addresses the way in which we can find out where the impulsive sources are. We propose a signal processing method that can identify an impulsive sources' location. The method is robust with respect to noise; a spatially distributed noise. Numerical simulation and experiments are performed to verify the method. Results show that the proposed technique is quite powerful for localizing the sources in noisy environments. The method also required less microphones than the conventional beamforming method.

Choi, Young-Chul; Kim, Yang-Hann

2007-06-01

351

Impulsive sources localisation in noisy environment using modified beamforming method  

Science.gov (United States)

When a machine has faults in its rotating part, it normally generates periodic vibration or acoustic signals. These signals are often periodic but impulsive. This paper addresses the way in which we can find where the impulsive sources are. We propose a signal processing method that can identify impulsive sources' location. The method is robust with respect to noise; spatially distributed noise. Numerical simulation and experiments are performed to verify the method. Results show that the proposed technique is quite powerful for localising the sources in noisy environments. The method also required less microphones than conventional beamforming method.

Choi, Young-Chul; Kim, Yang-Hann

2006-08-01

352

Synchronization of impulsively coupled complex systems with delay  

Science.gov (United States)

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

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

2011-09-01

353

The reshapers of current impulses for the contact welding  

Directory of Open Access Journals (Sweden)

Full Text Available The analysis and generalization of principles of construction of current impulses reshapers for the contact welding is conducted, taking into account new decisions in this domain and its progress modern trends. Signs on which it is possible to classify such devices are selected, and on the basis of these signs their modern classification is made. With the use of the offered classification chart the most perspective principle of construction of impulses reshapers for microwelding is selected. That is accumulation energy type reshaper of impulses without transformer on the basis of transistor regulators, workings in the continuous mode.

Paerand Yu. E.

2008-06-01

354

Chaos in three species food chain system with impulsive perturbations  

International Nuclear Information System (INIS)

In this paper, we investigate three species food chain system with periodic constant impulsive perturbations of mid-level predator. Conditions for extinction of lowest-level prey and top predator are given. By using the Floquet theory of impulsive equation and small amplitude perturbation skills, we consider the local stability of lowest-level prey and top predator eradication periodic solution. Further, influences of the impulsive perturbations on the inherent oscillation are studied numerically, which shows the rich dynamics (for example: period doubling, period halfing, non-unique dynamics) in the positive octant. The dynamics behavior is found to be very sensitive to the parameter values and initial value

2005-04-01

355

Correlation Between Steady State and Impulse Earth Resistance Values  

Directory of Open Access Journals (Sweden)

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

N. M. Nor

2009-01-01

356

Impulsive Control for Synchronization of Lorenz Chaotic System  

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Full Text Available Chaotic synchronization is the key technology of secure communication. In this paper,  an impulsive control method for chaotic synchronization of two coupled Lorenz chaotic system was proposed. The global asymptotic synchronization of two Lorenz systems was realized by using the linear error feedback of the state variables of the drive system and the response system as impulsive control signal. Based on stability theory of impulsive differential equation, conditions were obtained to guarantee the global asymptotic synchronization of two Lorenz systems. The theory analysis and computer simulation results validated its effectiveness.

2013-01-01

357

Impulse control in Kalman-like filtering problems  

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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.

Michael V. Basin

1998-01-01

358

Stability and asymptotic stability in impulsive semidynamical systems  

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Full Text Available In this paper we generalize two results of Lasalle's, the invariance theorem and asymptotic stability theorem of discrete and continuous semidynamical systems, to impulsive semidynamical systems.

Saroop K. Kaul

1994-01-01

359

Synchronization control for nonlinear stochastic dynamical networks: pinning impulsive strategy.  

Science.gov (United States)

In this paper, a new control strategy is proposed for the synchronization of stochastic dynamical networks with nonlinear coupling. Pinning state feedback controllers have been proved to be effective for synchronization control of state-coupled dynamical networks. We will show that pinning impulsive controllers are also effective for synchronization control of the above mentioned dynamical networks. Some generic mean square stability criteria are derived in terms of algebraic conditions, which guarantee that the whole state-coupled dynamical network can be forced to some desired trajectory by placing impulsive controllers on a small fraction of nodes. An effective method is given to select the nodes which should be controlled at each impulsive constants. The proportion of the controlled nodes guaranteeing the stability is explicitly obtained, and the synchronization region is also derived and clearly plotted. Numerical simulations are exploited to demonstrate the effectiveness of the pinning impulsive strategy proposed in this paper. PMID:24808507

Lu, Jianquan; Kurths, Jürgen; Cao, Jinde; Mahdavi, Nariman; Huang, Chi

2012-02-01

360

Synchronization of complex dynamical networks via impulsive control  

Science.gov (United States)

This paper investigates the problem of synchronization in complex dynamical networks. Based on the stability theory for impulsive differential equations, an impulsive control scheme is proposed to achieve impulsive synchronization for complex dynamical networks with unknown coupling. The synchronization strategy considers the influence of all nodes in the dynamical network and the effect intensity of every node to network synchronization relies on its weight in the network. For practical problems, by choosing appropriately the weights of the nodes in the network, network synchronization can be achieved by only a few useful nodes. Simulated examples are provided by using the chaotic Chua system as nodes of the dynamical network, and the effectiveness of the proposed impulsive control are demonstrated.

Zhang, Gang; Liu, Zengrong; Ma, Zhongjun

2007-12-01

 
 
 
 
361

3D model of impulse compaction of moulding sands model  

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

M. Ganczarek

2008-04-01

362

First- and second-order dynamic equations with impulse  

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Full Text Available We present existence results for discontinuous first- and continuous second-order dynamic equations on a time scale subject to fixed-time impulses and nonlinear boundary conditions.

D. C. Biles

2005-05-01

363

Multiple solutions for nonresonance impulsive functional differential equations  

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Full Text Available In this paper we investigate the existence of multiple solutions for first and second order impulsive functional differential equations with boundary conditions. Our main tool is the Leggett and Williams fixed point theorem.

Mouffak Benchohra

2003-05-01

364

Oscillation of high order linear functional differential equation with impulses  

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Full Text Available We study the solutions to high-order linear functional differential equations with impulses. We improve previous results in the oscillation theory for ordinary differential equations and obtain new criteria on the oscillation of solutions.

Haihua Liang

2005-08-01

365

On eventual stability of impulsive systems of differential equations  

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The notions of Lipschitz stability of impulsive systems of differential equations are extended and the notions of eventual stability are introduced. New notions called eventual and eventual Lipschitz stability. We give some criteria and results.

2001-01-01

366

Multiple solutions for nonresonance impulsive functional differential equations  

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In this paper we investigate the existence of multiple solutions for first and second order impulsive functional differential equations with boundary conditions. Our main tool is the Leggett and Williams fixed point theorem.

2003-01-01

367

Impulsive neutral functional differential inclusions with variable times  

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Full Text Available In this paper, we study the existence of solutions for first and second order impulsive neutral functional differential inclusions with variable times. Our main tool is a fixed point theorem due to Martelli for condensing multivalued maps.

Mouffak Benchohra

2003-06-01

368

On second order impulsive functional differential equations in Banach spaces  

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Full Text Available In this paper, a fixed point theorem due to Schaefer is used to investigate the existence of solutions for second order impulsive functional differential equations in Banach spaces.

M. Benchohra

2002-01-01

369

Variational Approach to Impulsive Differential Equations with Dirichlet Boundary Conditions  

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Full Text Available We study the existence of distinct pairs of nontrivial solutions for impulsive differential equations with Dirichlet boundary conditions by using variational methods and critical point theory.

Chen Huiwen

2010-01-01

370

Existence and uniqueness of solutions to impulsive fractional differential equations  

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

Boualem Attou Slimani

2009-01-01

371

Oscillation of nonlinear impulsive hyperbolic equations with several delays  

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Full Text Available In this paper, we study oscillatory properties of solutions to nonlinear impulsive hyperbolic equations with several delays. Sufficient conditions for oscillations of the solutions are established.

Anping Liu

2004-02-01

372

Synchronization of complex dynamical networks via impulsive control.  

Science.gov (United States)

This paper investigates the problem of synchronization in complex dynamical networks. Based on the stability theory for impulsive differential equations, an impulsive control scheme is proposed to achieve impulsive synchronization for complex dynamical networks with unknown coupling. The synchronization strategy considers the influence of all nodes in the dynamical network and the effect intensity of every node to network synchronization relies on its weight in the network. For practical problems, by choosing appropriately the weights of the nodes in the network, network synchronization can be achieved by only a few useful nodes. Simulated examples are provided by using the chaotic Chua system as nodes of the dynamical network, and the effectiveness of the proposed impulsive control are demonstrated. PMID:18163790

Zhang, Gang; Liu, Zengrong; Ma, Zhongjun

2007-12-01

373

Controllability of impulsive functional differential systems with nonlocal conditions  

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In this article, we study the controllability of impulsive functional differential equations with nonlocal conditions. We establish sufficient conditions for controllability, via the measure of noncompactness and Monch fixed point theorem.

2013-01-01

374

Controllability of impulsive functional differential systems with nonlocal conditions  

Directory of Open Access Journals (Sweden)

Full Text Available In this article, we study the controllability of impulsive functional differential equations with nonlocal conditions. We establish sufficient conditions for controllability, via the measure of noncompactness and Monch fixed point theorem.

Yansheng Liu

2013-08-01

375

On eventual stability of impulsive systems of differential equations  

Directory of Open Access Journals (Sweden)

Full Text Available The notions of Lipschitz stability of impulsive systems of differential equations are extended and the notions of eventual stability are introduced. New notions called eventual and eventual Lipschitz stability. We give some criteria and results.

A. A. Soliman

2001-11-01

376

Existence and uniqueness of solutions to impulsive fractional differential equations  

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

2009-01-01

377

Electrical Sterilization of Juice by Discharged HV Impulse Waveform  

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Full Text Available In the sterilization system by using HV impulse waveform, apple juice was sterilized with HV discharged oscillatory decay waveform. The optimal condition of impulse waveform for electrical sterilization has presented the excellent condition at 40kV cm?1, 4mH and over. The characteristics of this waveform shows oscillatory decay waveform with multiple pulses. And this impulse waveform was more effective to kill S. Cervisiae than exponential decay waveform. S. Cervisiae to become musty and sour for apple juice was used as the sample. This apple juice has good effect of electrical sterilization because of higher conductivity than water. Therefore this experiment can be treated sterilization without loss of vitamin C and original taste or perfume to apple juice. As a result, it is found that apple juice can be sterilized on 40kVcm?1, 4mH and over by using our designed HV impulse sterilizer.

Hee K. Lee

2006-01-01

378

Impulsive dynamic equations on a time scale  

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

Youssef N. Raffoul

2008-05-01

379

[Impulsive-compulsive syndrome in Parkinson's disease].  

Science.gov (United States)

Dopaminergic replacement therapy (DRT) is effective in treatment the motor symptoms of Parkinson's disease (PD) but can lead to impulse control disorders (ICD) in some patients. ICD include pathological gambling, hypersexuality, compulsive shopping, binge eating, punding, dopamine dysregulation syndrome (DDS). Authors studied the prevalence of ICD and its impact on the quality of life and daily activities of PD patients and their relatives. Among 246 patients studied, 55 patients (23%) (28 men, mean age 66.5±9.4 years) were diagnosed with ICD. DDS was noted in 36.4%, punding in 36.4%, binge eating in 23.6%, hypersexuality in 14.5%, compulsive shopping in 14.5% and pathological gambling in 1.8%. Of these 55 patients, 10 (18.1%) had symptoms of 2 of the ICDs: 3 (5.45%) had 3 of the ICDs and 2 (3.63%) patients had 5 of the ICDs. Quality of life ranged from 25% to 89%. Treatment approaches including the adjustment of doses of levodopa and dopamine receptor agonists in PD patients with ICD are presented. PMID:23994929

Nikitina, A V; Fedorova, N V

2013-01-01

380

Impulse control disorders in psychiatric inpatients.  

Science.gov (United States)

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

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

2011-08-15

 
 
 
 
381

Impulsive reactions to food-cues predict subsequent food craving.  

Science.gov (United States)

Low inhibitory control has been associated with overeating and addictive behaviors. Inhibitory control can modulate cue-elicited craving in social or alcohol-dependent drinkers, and trait impulsivity may also play a role in food-cue reactivity. The current study investigated food-cue affected response inhibition and its relationship to food craving using a stop-signal task with pictures of food and neutral stimuli. Participants responded slower to food pictures as compared to neutral pictures. Reaction times in response to food pictures positively predicted scores on the Food Cravings Questionnaire - State (FCQ-S) after the task and particularly scores on its hunger subscale. Lower inhibitory performance in response to food pictures predicted higher FCQ-S scores and particularly those related to a desire for food and lack of control over consumption. Task performance was unrelated to current dieting or other measures of habitual eating behaviors. Results support models on interactive effects of top-down inhibitory control processes and bottom-up hedonic signals in the self-regulation of eating behavior, such that low inhibitory control specifically in response to appetitive stimuli is associated with increased craving, which may ultimately result in overeating. PMID:24411760

Meule, Adrian; Lutz, Annika P C; Vögele, Claus; Kübler, Andrea

2014-01-01

382

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

Science.gov (United States)

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

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

383

Variational Method to the Impulsive Equation with Neumann Boundary Conditions  

Directory of Open Access Journals (Sweden)

Full Text Available We study the existence and multiplicity of classical solutions for second-order impulsive Sturm-Liouville equation with Neumann boundary conditions. By using the variational method and critical point theory, we give some new criteria to guarantee that the impulsive problem has at least one solution, two solutions, and infinitely many solutions under some different conditions, respectively. Some examples are also given in this paper to illustrate the main results.

Sun Juntao

2009-01-01

384

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

2013-11-25

385

Characterizing Impulse Radiating Antennas by an Intuitive Approach  

Science.gov (United States)

Referring to UWB-sensor applications and impulse radio, the ideal behavior of impulse radiating antennas will be summarized and some new characteristic functions will be introduced. The time domain Friis-formula will be derived based on normalized guided and free waves. By using the p-norm, a method is introduced to define the characteristic values and functions which can either refer to an antenna or yet the whole transmission chain.

Sachs, J.; Peyer, P.; Rauschenbach, P.; Tkac, F.; Zetik, R.

386

Dopamine and Impulse Control Disorders in Parkinson’s Disease  

Digital Repository Infrastructure Vision for European Research (DRIVER)

There is an increasing awareness that impulse control disorders (ICDs), including compulsive gambling, buying, sexual behavior, and eating, can occur as a complication of Parkinson’s disease (PD). In addition, other impulsive or compulsive disorders have been reported to occur, including dopamine dysregulation syndrome (DDS) and punding. Case reporting and prospective studies have reported an association between ICDs and the use of dopamine agonists (DAs), particularly at greater dosages, w...

2008-01-01

387

Input-to-state stability of nonlinear impulsive systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We prove that impulsive systems, which possess an ISS Lyapunov function, are ISS for time sequences satisfying the fixed dwell-time condition. If an ISS Lyapunov function is the exponential one, we provide a stronger result, which guarantees uniform ISS of the whole system over sequences satisfying the generalized average dwell-time condition. Then we prove two small-gain theorems that provide a construction of an ISS Lyapunov function for an interconnection of impulsive sys...

Dashkovskiy, Sergey; Mironchenko, Andrii

2012-01-01

388

Manipulation of plasma grating by impulsive molecular alignment  

Energy Technology Data Exchange (ETDEWEB)

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.

Lu, Peifen; Wu, Jian; Zeng, Heping [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China)

2013-11-25

389

Amphetamine Conditioned Place Preference in High and Low Impulsive Rats  

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Stimulants such as d-amphetamine (AMPH) are used commonly to treat attention-deficit hyperactivity disorder (ADHD), but concerns have been raised regarding the use of AMPH due to its reinforcing and potentially addictive properties. The current study examined if individual differences in impulsive choice predict AMPH-induced hyperactivity and conditioned place preference (CPP). Rats were first tested in delay discounting using an adjusting delay procedure to measure impulsive choice and then ...

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

2012-01-01

390

Error estimates for a stochastic impulse control problem  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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. For obtaining these bounds we build a sequence of stochastic impulse control problems, and a sequence of monotone approximation schemes. Extending methods of Barles and Jakobsen , we give error estimate for each problem of the sequence. Using these bounds we obtain the result. We obtain the same esti...

Bonnans, J. Frederic; Maroso, Stefania; Zidani, Hasnaa

2005-01-01

391

Correlation Between Steady State and Impulse Earth Resistance Values  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study presented experimental results of earthing systems under low-magnitude currents and under high impulse currents. The details of the measuring circuit involved for both types of testing were described. Three field sites were selected. At each site, three earth electrodes configurations were used. This makes up to nine earthing systems. From both low magnitude and impulse tests, the correlation between the steady state earth resistance value and the earth resistance under fast impuls...

Nor, N. M.; Rajab, R.

2009-01-01

392

Impulsivity and alcohol consumption in young social drinkers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Impulsivity may have different facets that contribute to drinking patterns in young people. This research examined how aspects of impulse control, especially the ability to inhibit a response, predicted recent alcohol use patterns in young social drinkers. Participants (N = 109) between the ages of 18 and 21 performed a cued go/no-go task that required quick responses to go targets and the inhibition of responses to no-go targets. Participants also completed several questionnaires that assess...

Henges, Amy L.; Marczinski, Cecile A.

2012-01-01

393

Impulse Buying Behaviour of Young Males in an Airport Environment  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Va?nnia?, Eeva

2013-01-01

394

THE IMPULSE RESPONSE FUNCTION ANALYSIS OF PORE PRESSURES MONITORING DATA  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Effective control of dam safety requires that the measured pore-pressure data be interpreted in the shortest possible time following the readings. Direct resolution based on partial differential equations are not appropriate. We present a relevant formalism for analysing pore-pressure monitoring data: the Impulse Response Function Analysis (IRFA) method. The model based on approximations for the impulse response of the dam gives the variations in the pore-pressure measurement resulting from c...

Bonelli, Stephane; Radzicki, Krzysztof

2007-01-01

395

Impulse response function analysis of pore pressure in earthdams  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Effective control of dam safety requires that the measured pore-pressure data be interpreted in the shortest possible time following the readings. Direct resolution based on partial differential equations are not appropriate. We present a relevant formalism for analysing pore-pressure monitoring data: the Impulse Response Function Analysis (IRFA) method. The model based on approximations for the impulse response of the dam gives the variations in the pore-pressure measurement resulting from c...

Radzicki, Krzysztof; Bonelli, Stephane

2007-01-01

396

Parental inconsistency, impulsive choice and neural value representations in healthy adolescents  

Science.gov (United States)

A well-characterized potential marker for addiction is impulsive choice, stably measured by delay discounting (DD) paradigms. While genetic influences partly account for inter-individual variance in impulsivity, environmental factors such as parenting practices may have an important role. The present study investigates how inconsistent fulfillment of delayed reward promises impacts on DD. A combined correlational and experimental functional magnetic resonance imaging (fMRI) design was performed in a sample of 48 healthy adolescents (13–15 years). More specifically, neural activation during a DD task was investigated at two assessment points (T0 and T1). Adolescents' self-reports of parenting and substance use were assessed at T0. Between assessment points, we experimentally varied the reliability of delayed reward promises, measuring the impact of this intervention on DD and neural value processing at T1. In the correlational part, same-sex parent reward inconsistency was associated with steeper DD and an attenuated subjective value (SV) representation in the nucleus accumbens (NAcc) and ventromedial prefrontal cortex (vmPFC). Steeper DD was in turn associated with alcohol use during the past year. In the experimental part, the reward inconsistency manipulation resulted in an attenuation of the NAcc SV representation, similar to the parental inconsistency effect. Together, our correlational and experimental findings raise new light on how parents may influence their children's degree of impulsivity, making parenting a potential target in addiction prevention.

Schneider, S; Peters, J; Peth, J M; Buchel, C

2014-01-01

397

STOP TALKING ! Inhibition of speech is affected by word frequency and dysfunctional impulsivity  

Directory of Open Access Journals (Sweden)

Full Text Available Speaking is a complex natural behavior that most people master very well. Nevertheless, systematic investigation of the factors that affect adaptive control over speech production is relatively scarce. The present experiments quantified and compared inhibitory control over manual and verbal responses using the stop-signal paradigm. In tasks with only two response alternatives, verbal expressions were slower than manual responses, but the stopping latencies of hand and verbal actions were comparable. When engaged in a standard picture-naming task using a large set of pictures, verbal stopping latencies were considerably prolonged. Interestingly, stopping was slower for naming words that are less frequently used compared to words that are used more frequently. These results indicate that adaptive action control over speech production is affected by lexical processing. This notion is compatible with current theories on speech self-monitoring. Finally, stopping latencies varied with individual differences in impulsivity, indicating that specifically dysfunctional impulsivity, and not functional impulsivity, is associated with slower verbal stopping.

WeryVan Den Wildenberg

2010-09-01

398

Hazard from intense low-frequency acoustic impulses. Final report  

Energy Technology Data Exchange (ETDEWEB)

It was predicted that because the ear is spectrally tuned, it should be most affected by intense impulses with spectral peaks near the frequency where it is tuned best (3.0 kHz for the human ear) and progressively less affected by impulses at lower frequencies. This prediction is counter to all the DRCs for impulse noise; therefore, an adequate test is essential. In order to augment the data on hearing loss to low-spectral-frequency impulses, three groups of cats (eight, nine, and ten animals) were exposed on one occasion to 50 impulses from a 105-mm howitzer at peak SPLs of 153, 159, and 166 dB. Threshold shifts were measured electrophysiologically on the day of exposure (CTS) and following a 2-month recovery period (PTS). Maximum PTSs appeared at 4 kHz (even though the spectral peak of the impulse had been at about 100 Hz), and CTSs recovered into PTSs about half as large. Furthermore, the group data, even small CTSs tended to have a permanent component. These data raise the question as to whether or not any threshold shift persisting an hour or two after exposure to high levels should be considered tolerable. When compared with data from rifle fire exposures, the data confirmed the earlier prediction that as the spectral frequency drops, hazard declines at the rate of a little more than 3 dB/oct, contrary to the rating by existing DRCs.

Price, G.R.

1986-10-01

399

The neuroscience of impulsive and self-controlled decisions.  

Science.gov (United States)

Impulsiveness and self-control are two antagonistic choice patterns. Whereas impulsive decisions can be exemplified by the preference for a small, immediate over a large, delayed reward, self-control can be characterised as the opposite preference order. This review focuses on current developments in investigating the neuroscience of impulsiveness and self-control, with particular emphasis on the neuroanatomy, psychopharmacology, and electrophysiology of this class of decision making. The role of the avian forebrain in representing and processing temporal reward discounting - a chief psychological mechanism responsible for producing impulsiveness - is especially highlighted. In addition to its role in impulsive decision making, the avian forebrain also appears to be involved in processing the key functions required for action- and self-control. In particular, recent electrophysiological studies indicate that single forebrain neurons reflect aspects of response omission strategy and the temporal scheduling of response withholding when execution of action needs to be controlled. In conclusion, the significant advances in this field of research may help to explain neuropathologies that are characterised by exaggerated impulsivity, or lack of self-control, as for instance attention deficit disorders, frontal lobe syndrome, drug addiction, or pathological gambling. PMID:16828187

Kalenscher, Tobias; Ohmann, Tobias; Güntürkün, Onur

2006-11-01

400

Implementation of powerful impulse ion beams in technologies. Chapter 5  

International Nuclear Information System (INIS)

Review of different trends of application of powerful impulse ion beams in technologies is given. Some shortcomings and advantages in comparison with laser technology and use of high-current electron beams are listed. There are following subdivisions in the chapter - 5.1. General tends on application of powerful impulse ion beams in technologies. Accelerators parameters; - 5.2. Elastic waves dynamics under powerful impulse ion beams irradiation; - 5.3. Wear mechanisms; - 5.4. Ion implantation influence on technical properties; - 5.5. Improvement of trybo technical properties of B 95 aluminium alloy by complex chemical and ion-beam processing; - 5.6. Modification of mechanical properties of metals and alloys by powerful impulse ion beams; - 5.7. Implantation, annealing and mixing; - 5.8. Applying of film coating; - 5. 9. Deluding of solid materials; - 5.10. Modification of ?-Fe under powerful impulse ion beams irradiation; - 5.11. Comparative analysis of powerful impulse ion and electron beams on ?-Fe; - 5.12. Ion irradiation action on beryllium; - 5.13. Formation of spatial hardened layers in steels; - 5.14. Role of some transformation processes and energy accumulation in mechanical hardening of steels under different kinds of radiation action; - 5.15. Investigation of residual deformation states in metals created by high-intensive ion irradiation; - 5.16. Model of depth metal hardening under high-intensive ion irradiation. 7 tabs., 54 figs

1998-01-01

 
 
 
 
401

Self-reported impulsivity and inhibitory control in problem gamblers.  

Science.gov (United States)

Impulsivity is considered a core feature of problem gambling; however, self-reported impulsivity and inhibitory control may reflect disparate constructs. We examined self-reported impulsivity and inhibitory control in 39 treatment-seeking problem gamblers and 41 matched controls using a range of self-report questionnaires and laboratory inhibitory control tasks. We also investigated differences between treatment-seeking problem gamblers who prefer strategic (e.g., sports betting) and nonstrategic (e.g., electronic gaming machines) gambling activities. Treatment-seeking problem gamblers demonstrated elevated self-reported impulsivity, more go errors on the Stop Signal Task, and a lower gap score on the Random Number Generation task than matched controls. However, overall we did not find strong evidence that treatment-seeking problem gamblers are more impulsive on laboratory inhibitory control measures. Furthermore, strategic and nonstrategic problem gamblers did not differ from their respective controls on either self-reported impulsivity questionnaires or laboratory inhibitory control measures. Contrary to expectations, our results suggest that inhibitory dyscontrol may not be a key component for some treatment-seeking problem gamblers. PMID:24479640

Lorains, Felicity K; Stout, Julie C; Bradshaw, John L; Dowling, Nicki A; Enticott, Peter G

2014-01-01

402

Impulsive moving mirror model and the stability of linear homogeneous differential equations with impulse effect in a Banach space.  

Science.gov (United States)

From a special class of systems has been used the linear homogeneous differential equations with impulse effect in Minkowski space field theory with time dependent boundary conditions, i.e. those of moving mirrors. The field theoretical approach for studi...

S. I. Kostadinov G. Petrov

1992-01-01

403

Analysis and design of set-stability for impulsive control systems  

International Nuclear Information System (INIS)

This Letter studies analysis and design of set-stability for impulsive control systems. A new comparison theorem of asymptotic set-stability for impulsive differential system is presented. Based on the new result, we derive some less conservative conditions for asymptotic set-stability of impulsive control systems with impulse at fixed times, and the results are used to design impulsive control laws of nonlinear systems for set-stability. A numerical example is used to verify the theoretical result

2007-10-29

404

Impulsive Behaviors as an Emotion Regulation Strategy: Examining Associations between PTSD, Emotion Dysregulation, and Impulsive Behaviors among Substance Dependent Inpatients  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Recent investigations have demonstrated that posttraumatic stress disorder (PTSD) is associated with a range of impulsive behaviors (e.g., risky sexual behavior and antisocial behavior). The purpose of the present study was to extend extant research by exploring whether emotion dysregulation explains the association between PTSD and impulsive behaviors. Participants were an ethnically diverse sample of 206 substance use disorder (SUD) patients in residential substance abuse treatment. Results...

2012-01-01

405

Impulsivity and Emotional Factors in Obesity: A Preliminary Study  

Directory of Open Access Journals (Sweden)

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

Fatma Özlem Orhan

2012-03-01

406

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

International Nuclear Information System (INIS)

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

2013-04-01

407

Dopamine agonists and risk: impulse control disorders in Parkinson's disease.  

Science.gov (United States)

Impulse control disorders are common in Parkinson's disease, occurring in 13.6% of patients. Using a pharmacological manipulation and a novel risk taking task while performing functional magnetic resonance imaging, we investigated the relationship between dopamine agonists and risk taking in patients with Parkinson's disease with and without impulse control disorders. During functional magnetic resonance imaging, subjects chose between two choices of equal expected value: a 'Sure' choice and a 'Gamble' choice of moderate risk. To commence each trial, in the 'Gain' condition, individuals started at $0 and in the 'Loss' condition individuals started at -$50 below the 'Sure' amount. The difference between the maximum and minimum outcomes from each gamble (i.e. range) was used as an index of risk ('Gamble Risk'). Sixteen healthy volunteers were behaviourally tested. Fourteen impulse control disorder (problem gambling or compulsive shopping) and 14 matched Parkinson's disease controls were tested ON and OFF dopamine agonists. Patients with impulse control disorder made more risky choices in the 'Gain' relative to the 'Loss' condition along with decreased orbitofrontal cortex and anterior cingulate activity, with the opposite observed in Parkinson's disease controls. In patients with impulse control disorder, dopamine agonists were associated with enhanced sensitivity to risk along with decreased ventral striatal activity again with the opposite in Parkinson's disease controls. Patients with impulse control disorder appear to have a bias towards risky choices independent of the effect of loss aversion. Dopamine agonists enhance sensitivity to risk in patients with impulse control disorder possibly by impairing risk evaluation in the striatum. Our results provide a potential explanation of why dopamine agonists may lead to an unconscious bias towards risk in susceptible individuals. PMID:21596771

Voon, Valerie; Gao, Jennifer; Brezing, Christina; Symmonds, Mkael; Ekanayake, Vindhya; Fernandez, Hubert; Dolan, Raymond J; Hallett, Mark

2011-05-01

408

Impulsividade e acidentes de trânsito Impulsiveness and traffic accidents  

Directory of Open Access Journals (Sweden)

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.

Marcus Maximilliano Araújo

2009-01-01

409

Screening Method Based on Walking Plantar Impulse for Detecting Musculoskeletal Senescence and Injury  

Science.gov (United States)

No consensus has been reached on how musculoskeletal system injuries or aging can be explained by a walking plantar impulse. We standardize the plantar impulse by defining a principal axis of plantar impulse. Based upon this standardized plantar impulse, two indexes are presented: plantar pressure record time series and plantar-impulse distribution along the principal axis of plantar impulse. These indexes are applied to analyze the plantar impulse collected by plantar pressure plates from three sources: Achilles tendon ruptures; elderly people (ages 62–71); and young people (ages 19–23). Our findings reveal that plantar impulse distribution curves for Achilles tendon ruptures change irregularly with subjects’ walking speed changes. When comparing distribution curves of the young, we see a significant difference in the elderly subjects’ phalanges plantar pressure record time series. This verifies our hypothesis that a plantar impulse can function as a means to assess and evaluate musculoskeletal system injuries and aging.

Fan, Yifang; Fan, Yubo; Li, Zhiyu; Newman, Tony; Lv, Changsheng; Zhou, Yi

2013-01-01

410

Conduits from community violence exposure to peer aggression and victimization: contributions of parental monitoring, impulsivity, and deviancy.  

Science.gov (United States)

Community violence exposure results in heightened risk for engaging in and being a victim of interpersonal violence. Despite this robust literature, few studies have specifically examined how the relation between community violence exposure, peer aggression, and victimization is modified by individual, peer, and familial influences (considered jointly). In the current study, we used risk and resiliency theory to examine links between community violence exposure and peer aggression and victimization. Impulsivity and parental monitoring were examined as potential moderators of the link between community violence exposure and outcomes, both directly and indirectly via deviant behavior. Survey data on bullying involvement, fighting, deviancy, parental monitoring, and impulsivity were collected on 3 occasions over an 18-month period among a large cohort of adolescents (N = 1,232) in 5th-7th grades. Structural equation modeling suggests that for both male and female adolescents, impulsivity exacerbates the effects of community violence exposure by increasing involvement in deviant behavior. Parental monitoring buffered the effects of community violence exposure on perpetration and victimization (for males and female adolescents) via reduced involvement in deviant behavior. Findings suggest that impulsivity and parental monitoring are implicated in modifying the effects of community violence exposure on both victimization and perpetration through deviancy, although deviancy is not as potent of a predictor for victimization. Thus, prevention efforts would seem to be optimally targeted at multiple ecological levels, including parental involvement and peer networks. PMID:24635595

Low, Sabina; Espelage, Dorothy

2014-04-01

411

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

Science.gov (United States)

Reviews and few non-controlled studies showed the effectiveness of several specific designed computer video-games as an additional form of treatment in several areas. However, there is a lack in the literature of specially designed serious-games for treating mental disorders. Playmancer (ICT European initiative) aims to develop and assess a serious videogame that may help to treat underlying processes (e.g. lack of self-control strategies) in Eating and Impulse control disorders. Preliminary data will be shown. PMID:19592756

Jiménez-Murcia, Susana; Fernández-Aranda, Fernando; Kalapanidas, Elias; Konstantas, Dimitri; Ganchev, Todor; Kocsis, Otilia; Lam, Tony; Santamaría, Juan J; Raguin, Thierry; Breiteneder, Christian; Kaufmann, Hannes; Davarakis, Costas

2009-01-01

412

Description of complex dynamics in a class of impulsive differential equations  

International Nuclear Information System (INIS)

Dynamical evolutions involving from equilibrium state to complex motion are prevalent not only in systems depicted by either continuous equations or discrete iterations but also in models governed by hybrid systems. In particular, chaotic motion could be found in hybrid systems whose dimension is even less than three. In this paper, we attempt to provide some concepts to describe various dynamics that occur in the simulations of a class of impulsive differential equations. Furthermore, some specific examples are also provided to illustrate these established concepts

2005-09-01

413

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

Science.gov (United States)

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

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

1972-01-01

414

Impulse noise in industrial plants: statistical distribution of levels.  

Science.gov (United States)

Impulse noise generated by industrial machines and occurring at a workplace is a cause of substantial hearing loss in workers. The paper presents data on workplace impulse noise, recorded in three plants of the machine industry. The data were collected in drop-forge, punch-press and machinery shops. The results of the measurements are shown as cumulative relative frequency distributions of the C-weighted peak sound pressure level, L(Cpeak), the A-weighted maximum RMS sound pressure level (SPL), L(Amax), and the A-weighted sound exposure level, L(EA) of isolated acoustic impulse noises. The survey shows that in the drop-forge shop over 90% of acoustic impulses generated by hammer strikes exceed permissible levels of L(Cpeak) = 135 dB and L(Amax) = 115 dB. In the stamp-press shop, only 10-20% of impulses generated during the technological process exceed maximum permissible levels. PMID:11548061

Zera, J

2001-01-01

415

Open-loop dereverberation of multichannel room impulse responses  

Science.gov (United States)

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.

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

2003-04-01

416

Drug Addiction Endophenotypes: Impulsive Versus Sensation-Seeking Personality Traits  

Science.gov (United States)

Background Genetic factors have been implicated in the development of substance abuse disorders, but the role of pre-existing vulnerability in addiction is still poorly understood. Personality traits of impulsivity and sensation-seeking are highly prevalent in chronic drug users and have been linked with an increased risk for substance abuse. However, it has not been clear whether these personality traits are a cause or an effect of stimulant drug dependence. Method We compared self-reported levels of impulsivity and sensation-seeking between 30 sibling pairs of stimulant-dependent individuals and their biological brothers/sisters who did not have a significant drug-taking history and 30 unrelated, nondrug-taking control volunteers. Results Siblings of chronic stimulant users reported significantly higher levels of trait-impulsivity than control volunteers but did not differ from control volunteers with regard to sensation-seeking traits. Stimulant-dependent individuals reported significantly higher levels of impulsivity and sensation-seeking compared with both their siblings and control volunteers. Conclusions These data indicate that impulsivity is a behavioral endophenotype mediating risk for stimulant dependence that may be exacerbated by chronic drug exposure, whereas abnormal sensation-seeking is more likely to be an effect of stimulant drug abuse.

Ersche, Karen D.; Turton, Abigail J.; Pradhan, Shachi; Bullmore, Edward T.; Robbins, Trevor W.

2010-01-01

417

Solar Flare Impulsive Phase Emission Observed with SDO/EVE  

Science.gov (United States)

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.

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

2013-12-01

418

Impulse Volt-Time Characteristics of Oil and OIP Insulation  

Directory of Open Access Journals (Sweden)

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%.

S. Venkatesan

2005-01-01

419

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Impulsive individuals make risky choices, motivated more by immediate reward than potential long-term negative consequences. We used event-related potentials to study the impact of reward and punishment sensitivity in impulsivity on risky decision-making in a two-card choice task in groups of 14 high and 14 low impulsive undergraduates formed by a median split on the Barratt Impulsiveness Scale score. The high impulsives had a larger P3 and the low impulsives a smaller P3 to the cards when ma...

Martin, Laura E.; Potts, Geoffrey F.

2009-01-01

420

Four factors of impulsivity differentiate antisocial and borderline personality disorders.  

Science.gov (United States)

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

DeShong, Hilary L; Kurtz, John E

2013-04-01

 
 
 
 
421

A review of impulse turbines for wave energy conversion  

Energy Technology Data Exchange (ETDEWEB)

Oscillating Water Column based wave energy plants convert wave energy into low pressure pneumatic power in the form of bi-directional air flows. Air turbines which are capable of rotating uni-directionally in bi-directional air flow, otherwise also known as self-rectifying turbines, are used to extract mechanical shaft power which is further converted into electrical power by a generator. This paper reviews the state of the art in self-rectifying impulse air turbines. New results on optimum parameters for the fixed-guide-vane impulse turbine are also presented. Starting characteristics and conversion efficiencies of two types of impulse turbines are compared with the well known Wells turbine. (Author)

Setoguchi, T.; Takao, M.; Kaneko, K. [Saga Univ., Dept. of Mechanical Engineering, Saga (Japan); Santhakumar, S. [Indian Inst. of Technology, Dept. of Aerospace Engineering, Madras (India); Maeda, H. [Torishima Pump Manufacturing Co. Ltd., Saga (Japan)

2001-06-01

422

Short pulses and reaction dynamics; Impulsions courtes et dynamique reactionnelle  

Energy Technology Data Exchange (ETDEWEB)

The observation in real time of molecular dynamics can be achieved by using an ultra-brief laser which delivers impulses shorter than the vibration period of the molecule to be examined. This experiment has been made with NaI molecule. A first laser impulse has put the molecule in an excited state and a series of ultra-brief impulses has given information on the movement of nuclei inside the molecule. The irradiation of matter with very energetic photon beams leads to the bursting of molecules. Today such photons are provided either by synchrotron radiation or high-power laser beams. The bursting involves 2 successive stages: the excitation then the fragmentation of the molecule. The ionic fragments are analysed by using a time of flight mass spectrometer, this technique has been applied to the bursting of the ClBrCH{sub 2} molecule. (A.C.)

Mons, M.; Gregoire, G.; Schmidt, M.; Normand, D.; Cornaggia, Ch.; Simon, M.; Morin, P.; Nenner, I. [CEA/Saclay, Dept. de Recherche sur l' Etat Condense, les Atomes et les Molecules (DRECAM), 91 - Gif-sur-Yvette (France); Jouvet, Ch. [Centre National de la Recherche Scientifique (CNRS), 91 - Orsay (France). Lab. de Photophysique Moleculaire; Morin, P. [Centre National de la Recherche Scientifique (CNRS), 91 - Orsay (France). Laboratoire pour l' Utilisation du Rayonnement Electromagnetique

1999-07-01

423

IMPULSE NOISE REMOVAL FROM MEDICAL IMAGES USING FUZZY GENETIC ALGORITHM  

Directory of Open Access Journals (Sweden)

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.

Anisha K K

2011-01-01

424

Impulse Noise Removal from Medical Images Using Fuzzy Genetic Algorithm  

Directory of Open Access Journals (Sweden)

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

Anisha K K

2011-12-01

425

Robust impulsive synchronization of complex delayed dynamical networks  

Energy Technology Data Exchange (ETDEWEB)

This Letter investigates robust impulsive synchronization of complex delayed dynamical networks with nonsymmetrical coupling from the view of dynamics and control. Based on impulsive control theory on delayed dynamical systems, some simple yet generic criteria for robust impulsive synchronization are established. It is shown that these criteria can provide a novel and effective control approach to synchronize an arbitrary given delayed dynamical network to a desired synchronization state. Comparing with existing results, the advantage of the control scheme is that synchronization state can be selected as a weighted average of all the states in the network for the purpose of practical control strategy. Finally, numerical simulations are given to demonstrate the effectiveness of the proposed control methodology.

Cai Shuiming [Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072 (China); Zhou Jin [Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072 (China)], E-mail: Jinzhousu@yahoo.com.cn; Xiang Lan [Department of Physics, Shanghai University, Shanghai 200444 (China); Liu Zengrong [Institute of System Biology, Shanghai University, Shanghai 200444 (China)

2008-07-21

426

Robust impulsive synchronization of complex delayed dynamical networks  

International Nuclear Information System (INIS)

This Letter investigates robust impulsive synchronization of complex delayed dynamical networks with nonsymmetrical coupling from the view of dynamics and control. Based on impulsive control theory on delayed dynamical systems, some simple yet generic criteria for robust impulsive synchronization are established. It is shown that these criteria can provide a novel and effective control approach to synchronize an arbitrary given delayed dynamical network to a desired synchronization state. Comparing with existing results, the advantage of the control scheme is that synchronization state can be selected as a weighted average of all the states in the network for the purpose of practical control strategy. Finally, numerical simulations are given to demonstrate the effectiveness of the proposed control methodology

2008-07-21

427

Impulsive control strategies in biological control of pesticide.  

Science.gov (United States)

By presenting and analyzing the pest-predator model under insecticides used impulsively, two impulsive strategies in biological control are put forward. The first strategy: the pulse period is fixed, but the proportional constant E(1) changes, which represents the fraction of pests killed by applying insecticide. For this scheme, two thresholds, E(1)(**) and E(1)(*) for E(1) are obtained. If E(1)>or=E(1)(*), both the pest and predator (natural enemies) populations go to extinction. If E(1)(**)strategy: the proportional constant E(1) is fixed (E(1)controlling the period impulsive effect tau

Lu, Zhonghua; Chi, Xuebin; Chen, Lansun

2003-08-01

428

Robust impulsive synchronization of complex delayed dynamical networks  

Science.gov (United States)

This Letter investigates robust impulsive synchronization of complex delayed dynamical networks with nonsymmetrical coupling from the view of dynamics and control. Based on impulsive control theory on delayed dynamical systems, some simple yet generic criteria for robust impulsive synchronization are established. It is shown that these criteria can provide a novel and effective control approach to synchronize an arbitrary given delayed dynamical network to a desired synchronization state. Comparing with existing results, the advantage of the control scheme is that synchronization state can be selected as a weighted average of all the states in the network for the purpose of practical control strategy. Finally, numerical simulations are given to demonstrate the effectiveness of the proposed control methodology.

Cai, Shuiming; Zhou, Jin; Xiang, Lan; Liu, Zengrong

2008-07-01

429

Three-dimensional, Impulsive Magnetic Reconnection in a Laboratory Plasma  

Energy Technology Data Exchange (ETDEWEB)

Impulsive, local, 3-D reconnection is identified for the first time in a laboratory current sheet. The events observed in the Magnetic Reconnection Experiment (MRX) are characterized by large local gradients in the third direction and cannot be explained by 2-D models. Detailed measurements show that the ejection of flux rope structures from the current sheet plays a key role in these events. By contrast, even though electromagnetic fluctuations in the lower hybrid frequency range are also observed concurrently with the impulsive behavior, they are not the key physics responsible. A qualitative, 3-D, two-fluid model is proposed to explain the observations. The experimental results may be particularly applicable to space and astrophysical plasmas where impulsive reconnection occurs.

S Dorfman, et al

2013-05-03

430

THz impulse radar for biomedical sensing: nonlinear system behavior  

Science.gov (United States)

The THz impulse radar is an "RF-inspired" sensor system that has performed remarkably well since its initial development nearly six years ago. It was developed for ex vivo skin-burn imaging, and has since shown great promise in the sensitive detection of hydration levels in soft tissues of several types, such as in vivo corneal and burn samples. An intriguing aspect of the impulse radar is its hybrid architecture which combines the high-peak-power of photoconductive switches with the high-responsivity and -bandwidth (RF and video) of Schottky-diode rectifiers. The result is a very sensitive sensor system in which the post-detection signal-to-noise ratio depends super-linearly on average signal power up to a point where the diode is "turned on" in the forward direction, and then behaves quasi-linearly beyond that point. This paper reports the first nonlinear systems analysis done on the impulse radar using MATLAB.

Brown, E. R.; Sung, Shijun; Grundfest, W. S.; Taylor, Z. D.

2014-03-01

431

Application of E^p-Stability to Impulsive Financial Model  

Directory of Open Access Journals (Sweden)

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.

Sam Olatunji Ale

2013-07-01

432

Experimental study on impulsive liquid pressure by sloshing  

International Nuclear Information System (INIS)

Pool type FBR (Fast Breeder Reactor) vessel contains large quantity (about 3,000 ? 4,000 tons) of high temperature (about 400 ? 500degC) liquid sodium with free surface. Sloshing wave gradually grow during earthquake and this liquid surface may collide with under roof of reactor vessel, cousing large impulsive pressure on heat insulator assembly under the roof. In this paper, we describe an experimental study of impulsive pressure by sloshing. Model used in this experiments are cylindrical (2.2 m Diameter; 1 m Depth), and two rectangular (6.7 m Length, 2 m Width; 2.5 m Depth, and 0.55 m Length; 0.2 m Width; 0.2 m Depth) models. In this experiment, we use water instead of liquid sodium, because water can be handled more easily than liquid sodium. From the experimental results, we derived a formula to obtain impulsive pressure value. (author)

1989-01-01

433

A Methodology for Rapid Prototyping Peak-Constrained Least-Squares Bit-Serial Finite Impulse Response Filters in FPGAs  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Area-efficient peak-constrained least-squares (PCLS) bit-serial finite impulse response (FIR) filter implementations can be rapidly prototyped in field programmable gate arrays (FPGA) with the methodology presented in this paper. Faster generation of the FPGA configuration bitstream is possible with a new application-specific mapping and placement method that uses JBits to avoid conventional general-purpose mapping and placement tools. JBits is a set of Java classes that provide an in...

2003-01-01

434

Single-impulse magnetic focusing of launched cold atoms  

International Nuclear Information System (INIS)

We have theoretically investigated the focusing of a launched clou