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1

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

Science.gov (United States)

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

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

2012-01-01

2

Rapid Estimation of Specific Impulse  

Directory of Open Access Journals (Sweden)

Full Text Available Specific impulse (Isp is one of the important criteria for propellant characterisation. In the present paper a semiempirical approach has been suggested to calculate Isp of composite modified doublebase(CMDB propellant formulations by utilizing calorimetric value(Cal-Val of the propellant composition. The Cal-Val of aluminium has been computed on the basis of oxygen balance of the propellant composition. The validity of the new approach has been demonstratedby comparing predicted values witli actual results.

V. K. Bhat

2013-08-01

3

Specific Impulse and Mass Flow Rate Error  

Science.gov (United States)

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

Gregory, Don A.

2005-01-01

4

Ultrahigh Specific Impulse Nuclear Thermal Propulsion  

Energy Technology Data Exchange (ETDEWEB)

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

Anne Charmeau; Brandon Cunningham; Samim Anghaie

2009-02-09

5

Domain-Specific Impulsivity in School-Age Children  

Science.gov (United States)

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

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

2013-01-01

6

Impulsivity.  

Science.gov (United States)

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

Hollander, E; Rosen, J

2000-01-01

7

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

8

Unique aspects of impulsive traits in substance use and overeating: specific contributions of common assessments of impulsivity  

Science.gov (United States)

Background Impulsivity is a complex trait often studied in substance abuse and overeating disorders, but the exact nature of impulsivity traits and their contribution to these disorders are still debated. Thus, understanding how to measure impulsivity is essential for comprehending addictive behaviors. Objectives Identify unique impulsivity traits specific to substance use and overeating. Methods Impulsive Sensation Seeking (ImpSS) and Barratt’s Impulsivity scales (BIS) Scales were analyzed with a non-parametric factor analytic technique (discriminant correspondence analysis) to identify group-specific traits on 297 individuals from five groups: Marijuana (n = 88), Nicotine (n = 82), Overeaters (n = 27), Marijuauna + Nicotine (n = 63), and Controls (n = 37). Results A significant overall factor structure revealed three components of impulsivity that explained respectively 50.19% (pperm<0.0005), 24.18% (pperm<0.0005), and 15.98% (pperm<0.0005) of the variance. All groups were significantly different from one another. When analyzed together, the BIS and ImpSS produce a multi-factorial structure that identified the impulsivity traits specific to these groups. The group specific traits are (1) Control: low impulse, avoids thrill-seeking behaviors; (2) Marijuana: seeks mild sensation, is focused and attentive; (3) Marijuana + Nicotine: pursues thrill-seeking, lacks focus and attention; (4) Nicotine: lacks focus and planning; (5) Overeating: lacks focus, but plans (short and long term). Conclusions Our results reveal impulsivity traits specific to each group. This may provide better criteria to define spectrums and trajectories – instead of categories – of symptoms for substance use and eating disorders. Defining symptomatic spectrums could be an important step forward in diagnostic strategies. PMID:25115831

Beaton, Derek; Abdi, Hervé; Filbey, Francesca M.

2015-01-01

9

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

10

Simulation of Trajectories for High Specific Impulse Deep Space Exploration  

Science.gov (United States)

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

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

2002-01-01

11

Variable thrust/specific-impulse of multiplexed electrospray microthrusters  

Science.gov (United States)

We report on the development of a single-propellant ElectroSpray (ES) microthruster able to: (a) cover a wide range of specific impulse (Isp) and thrust at high propulsion efficiency, and (b) provide macroscopic thrust via micro-fabricated emitter arrays. The electrospray is a mature technology for the emission of fast nanodroplets at a propulsive efficiency larger than 50% over the full Isp range. The size of the droplets depends on the propellant flow rate and the physical properties of the electrolyte, especially the electric conductivity. To achieve a useful thrust one needs to multiplex the ES by operating many in parallel, which we achieve via silicon microfabrication of arrays of multiple and identical nozzles. The Multiplexed Electrospray (MES) micro-thruster is composed mainly of two electrodes: a nozzle-array and an extractor electrode, between which the electric field needed to form the ES is established. We tested nozzle arrays with up to 37 capillaries, that are spaced 1mm apart, with ID/OD = 10/30? m. The capillaries are filled with 2.01? m silicon dioxide beads to increase the hydraulic impedance and ensure uniform flow rate through the different emitters. A third electrode (accelerator) is mounted downstream the extractor to accelerate the droplets, thereby increasing the microthruster performance. The system is packaged in an alumina casing for electrical insulation and propellant feed. Tests run in a vacuum chamber at a pressure ? 10-5 mbar demonstrated reliable operation for several hours with a relatively high beam energy of 7.56kV. The 37-nozzle MES device was tested with the ionic liquid ethylammonium nitrate (EAN), at estimated total flow rates between 1.2 and 14 ? L/h, emitted currents between 14.2 and 23.0 ? A, specific impulse ranging between 710 and 1930s, and thrust ranging between 7.5 and 33 ? N. EAN is well suited to cover a relatively broad range of charge/mass- at an average propulsion efficiency of 66%. With further scale-up to a 600-MES system, the device would be suitable for micro-satellites missions such as attitude control and station keeping.

Lenguito, G.; Fernandez de la Mora, J.; Gomez, A.

12

Trajectories for High Specific Impulse High Specific Power Deep Space Exploration  

Science.gov (United States)

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

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

2002-01-01

13

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

Science.gov (United States)

Dysfunctional decision-making in individuals with pathological gambling (PGs) may result from dominating reward-driven processes, indicated by higher impulsivity. In the current study we examined (1) if PGs show specific decision-making impairments related to dominating reward-driven processes rather than to strategic planning deficits and (2) whether these impairments are related to impulsivity. Nineteen PGs according to DSM-IV and 19 matched control subjects undertook the Cambridge Gambling Task (CGT) to assess decision-making. The delay discounting paradigm (DDP) as well as the UPPS Impulsive Behavior Scale (measuring urgency, premeditation, perseverance and sensation seeking) were administered as multidimensional measures of impulsivity. Results revealed that (1) PGs exhibited higher risk seeking and an immediate reward focus in the CGT and, in contrast, comparable strategic planning to the control group. (2) Decision-making impairments were related to more severe delay discounting and, specifically, to increased urgency and less premeditation. Our findings suggest (1) the necessity to disentangle decision-making components in order to improve etiological models of PGs, and (2) that urgency and premeditation are specifically related to disadvantageous decision-making and should be tackled in intervention strategies focusing on emotion tolerance and control strategies. PMID:24434041

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

2014-03-30

14

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

International Nuclear Information System (INIS)

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

15

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

Energy Technology Data Exchange (ETDEWEB)

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

Fivez, J [HUB, Stormstraat 2, B-1000 Brussel (Belgium); Salenbien, R; Malayil, M Kuriakose; Schols, W; Glorieux, C, E-mail: christ.glorieux@fys.kuleuven.b [Laboratorium voor Akoestiek en Thermische Fysica, Department Natuurkunde en Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B- 3001 Leuven (Belgium)

2011-01-01

16

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

17

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

Energy Technology Data Exchange (ETDEWEB)

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

Whitehead, J.C.

1996-06-06

18

The hysteresis phenomena in a collisional magnetoplasma  

International Nuclear Information System (INIS)

The discontinuous transitions between two magnetoplasma temperature states due to resonant Joule heating analysed. In the vicinity of Langmuir electron resonance the refraction index, the absorption coefficient and the energy flux direction of the extraordinary wave are characterized by considerable hysteresis exchanges via the thermic effects. These exchanges may lead to the jump-like deflection of the wave energy flux from some region inside the transparent plasma layer. (author)

19

Alfvenic shock waves in a collisional magnetoplasma  

International Nuclear Information System (INIS)

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

20

Magnetoplasma resonance of electron-hole drops in germanium  

International Nuclear Information System (INIS)

Magnetic field dependence of the carrier pair density in the electron-hole drop is obtained for pure germanium from magnetoplasma resonance experiments by far-infrared lasers. Peak positions of magnetoplasma resonances are analyzed by Mie's scattering theory. Effects of impurities on the carrier pair density and scattering relaxation time are also explored. (Auth.)

 
 
 
 
21

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

22

Vortex Street in Homogeneous Dense Dusty Magnetoplasma  

Science.gov (United States)

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

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

2014-12-01

23

Jeans stability in collisional quantum dusty magnetoplasmas  

International Nuclear Information System (INIS)

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

24

Jeans stability in collisional quantum dusty magnetoplasmas  

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-09-15

25

Electrostatic global vortices in a nonuniform cylindrical magneto-plasma  

Energy Technology Data Exchange (ETDEWEB)

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.

Saleem, H., E-mail: saleemhpk@hotmail.com [National Centre for Physics, Quaid-i-Azam University Campus, Islamabad 44000 (Pakistan); International Centre for Advanced Studies in Physical Sciences, Faculty of Physics and Astronomy, Ruhr University Bochum, D-44780 Bochum (Germany); Shukla, P.K. [International Centre for Advanced Studies in Physical Sciences, Faculty of Physics and Astronomy, Ruhr University Bochum, D-44780 Bochum (Germany); Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 93093 (United States)

2012-01-09

26

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.

27

Energy Deposition via Magnetoplasma-dynamic Acceleration  

International Nuclear Information System (INIS)

A time-dependent, two-dimensional, axisymmetric magnetohydrodynamics code is employed to model, validate and extend the experimentally-limited performance characteristics of a Gigawatt-level plasma source that utilized magnetoplasma-dynamic acceleration for gas energy deposition. Accurate modeling required an upgrade of the code's circuit routines to properly capture the Pulse-Forming-Network current waveform which also serves as the primary variable for validation. Comparisons to experimentally deduced current waveforms were in good agreement for all power levels. The simulations also produced values for the plasma voltage which were compared to the measured voltage across the electrodes. Trend agreement was encouraging while the magnitude of the discrepancy is approximately constant and interpreted as a representation of electrode fall voltage. Force computations captured the expected electromagnetic acceleration trends and serve as further verification. They also allow examination of the device as a very-high power magnetoplasma-dynamic thruster operating at power levels in the excess of 180 MW. The computations offer insights into the plasma's characteristics at different power levels through two-dimensional distributions of pertinent parameters and identify design guidelines for effective stagnation temperature values as a function of mass-flow rate. (authors)

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)

29

Sex differences in impulsive action and impulsive choice.  

Science.gov (United States)

Here, we review the evidence for sex differences in behavioral measures of impulsivity for both humans and laboratory animals. We focus on two specific components of impulsivity: impulsive action (i.e., difficulty inhibiting a prepotent response) and impulsive choice (i.e., difficulty delaying gratification). Sex differences appear to exist on these measures, but the direction and magnitude of the differences vary. In laboratory animals, impulsive action is typically greater in males than females, whereas impulsive choice is typically greater in females. In humans, women discount more steeply than men, but sex differences on measures of impulsive action depend on tasks and subject samples. We discuss implications of these findings as they relate to drug addiction. We also point out the major gaps in this research to date, including the lack of studies designed specifically to examine sex differences in behavioral impulsivity, and the lack of consideration of menstrual or estrous phase or sex hormone levels in the studies. PMID:24286704

Weafer, Jessica; de Wit, Harriet

2014-11-01

30

Mach cones in space and laboratory dusty magnetoplasmas  

International Nuclear Information System (INIS)

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

31

Whistler waves guided by density depletion ducts in a magnetoplasma  

Science.gov (United States)

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

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

2010-11-01

32

Whistler waves guided by density depletion ducts in a magnetoplasma  

International Nuclear Information System (INIS)

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

33

Impedance of a large circular loop antenna in a magnetoplasma  

Science.gov (United States)

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

Ohnuki, S.; Sawaya, K.; Adachi, S.

1986-08-01

34

Impedance of a large circular loop antenna in a magnetoplasma  

International Nuclear Information System (INIS)

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

35

Ultrastrong stationary double layers in a nondischarge magnetoplasma  

International Nuclear Information System (INIS)

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

36

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

37

Drift wave turbulence in a dense semiclassical magnetoplasma  

CERN Document Server

A semiclassical nonlinear collisional drift wave model for dense magnetized plasmas is developed and solved numerically. The effects of fluid electron density fluctuations associated with quantum statistical pressure and quantum Bohm force are included, and their influences on the collisional drift wave instability and the resulting fully developed nanoscale drift wave turbulence are discussed. It is found that the quantum effects increase the growth rate of the collisional drift wave instability, and introduce a finite de Broglie length screening on the drift wave turbulent density perturbations. The relevance to nanoscale turbulence in nonuniform dense magnetoplasmas is discussed.

Kendl, Alexander

2011-01-01

38

Electromagnetic solitary structures in dense electron-positron-ion magnetoplasmas  

Energy Technology Data Exchange (ETDEWEB)

The linear and nonlinear propagation characteristics of low-frequency obliquely propagating magnetoacoustic waves in dense electron-positron-ion magnetoplasmas are studied in this paper by using the quantum magnetohydrodynamic (QMHD) model. A quantum Kadomtsev-Petviashvili (KP) equation is derived by using the reductive perturbation technique. The dependence of the fast and slow magnetoacoustic solitary waves on the positron concentration, the obliqueness parameter {theta} and the magnetic field is also investigated. The present investigation may have relevance to dense astrophysical environments where the quantum effects are expected to dominate.

Masood, W; Hussain, S; Rizvi, H; Mushtaq, A [TPPD, PINSTECH, PO Nilore, Islamabad (Pakistan); Ayub, M, E-mail: waqasmas@gmail.co [Government College University (GCU), Lahore (Pakistan)

2010-12-15

39

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

40

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

International Nuclear Information System (INIS)

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

 
 
 
 
41

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

42

Impulsive control for fast nanopositioning  

International Nuclear Information System (INIS)

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

43

Impulsive control for fast nanopositioning  

Energy Technology Data Exchange (ETDEWEB)

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

Tuma, Tomas; Sebastian, Abu; Haeberle, Walter; Pantazi, Angeliki [IBM Research-Zurich, Saeumerstrasse 4, 8803 Rueschlikon (Switzerland); Lygeros, John, E-mail: uma@zurich.ibm.com, E-mail: ase@zurich.ibm.com, E-mail: wha@zurich.ibm.com, E-mail: lygeros@control.ee.ethz.ch, E-mail: agp@zurich.ibm.com [Automatic Control Laboratory, Swiss Federal Institute of Technology, Physikstrasse 3, 8092 Zurich (Switzerland)

2011-04-01

44

Electric field variability and classifications of Titan's magnetoplasma environment  

CERN Document Server

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

Arridge, Chris; Guio, Patrick

2011-01-01

45

Magnetoplasma resonance in electron-hole drops in germanium  

International Nuclear Information System (INIS)

A theory of magnetoplasma resonance (MPR) in electron-hole drops (EHD) in germanium is considered, the real quantum spectrum of the Ge carriers is taken into account as well as the shape of the drops in the magnetic field. The main regularities pertaining to the MPR in END are analyzed. Some of the most important parameters characterizing the electron-hole fluid in Ge are determined by comparing the theory and experimental data. These are the effective carrier masses, variation of the theory and experimental data. These are the effective carrier masses, variation of the equilibrium particle concentration in the drops induced by a magnetic field up to 40 kOe and so oriented tha Hlong [100] and Hlong [111], dependence of the momentum relaxation time of the carrier on the photon frequency and the magnetic field intensity. Various mechanisms of plasmon damping in Ge EHD are analyzed

46

Compression zone formation in magnetoplasma compressor operating with heavy gases  

International Nuclear Information System (INIS)

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

47

Temperature effects on the beat heating of a collisional magnetoplasma  

International Nuclear Information System (INIS)

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

48

Nonlinear electrostatic shock waves in inhomogeneous dense dusty magnetoplasmas  

Energy Technology Data Exchange (ETDEWEB)

The Linear and nonlinear propagation characteristics of drift dust acoustic waves were studied in an inhomogeneous electron-ion-dust (e-i-d) quantum magnetoplasma with neutrals in the background using the well-known quantum hydrodynamic (QHD) model. The Korteweg-de Vries-Burgers (KdVB) and Kadomtsev-Petviashvili-Burgers (KPB) equations are obtained. Furthermore, the solutions of the KdVB and KPB equations are presented using the tangent hyperbolic (tanh) method. The variation of the shock profile with the quantum Bohm potential, collision frequency, ratio of drift to shock velocity in the co-moving frame and effect of magnetic field is also investigated. The relevance of the present investigation to dense astrophysical environments is also highlighted.

Masood, W [TPPD, PINSTECH, PO Nilore, Islamabad (Pakistan); Karim, S; Shah, H A, E-mail: waqasmas@gmail.co [Department of Physics, GC University, 54000 Lahore (Pakistan)

2010-10-15

49

Wave modes in a magnetoplasma with anisotropic perturbation pressure  

Science.gov (United States)

The momentum balance equation and the balance equation for the pressure tensor of a collision-free one-species magnetoplasma are linearized and Fourier-transformed, together with Maxwell's curl equations. They are combined in an algebraic dispersion system for the average perturbation velocity of the plasma particles. To do this a set of five fourth-order projectors is introduced, constructed with the aid of a commutative ‘ring product’ of two second-order projectors. It is shown that the trace-free part of the anisotropic perturbation pressure tensor, usually ignored for the sake of simplicity in such analyses, is of the same order of magnitude as the trace of this tensor. The vanishing determinant of the dispersion system is the dispersion equation of fifth degree in the square of the refractive index.

Suchy, K.; Altman, C.

2003-01-01

50

Amplitude modulated drift wave packets in a nonuniform magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-08-06

51

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

52

Kinetic closure conditions for quasi-stationary collisionless axisymmetric magnetoplasmas  

Science.gov (United States)

A characteristic feature of fluid theories concerns the difficulty of uniquely defining consistent closure conditions for the fluid equations. In fact it is well known that fluid theories cannot generally provide a closed system of equations for the fluid fields. This feature is typical of collisionless plasmas where, in contrast to collisional plasmas, asymptotic closure conditions do not follow as a consequence of an H-theorem This issue is of particular relevance in astrophysics where fluid approaches are usually adopted. On the other hand, it is well known that the determination of the closure conditions is in principle achievable in the context of kinetic theory. In the case of multi-species thermal magnetoplasmas this requires the determination of the species tensor pressure and of the corresponding heat fluxes. In this paper we investigate this problem in the framework of the Vlasov-Maxwell description for collisionless axisymmetric magnetoplasmas arising in astrophysics, with particular reference to accretion discs around compact objects (like black holes and neutron stars). The dynamics of collisionless plasmas in these environments is determined by the simultaneous presence of gravitational and magnetic fields, where the latter may be both externally produced and self-generated by the plasma currents. Our starting point here is the construction of a solution for the stationary distribution function describing slowly-varying gyrokinetic equilibria. The treatment is applicable to non-relativistic axisymmetric systems characterized by temperature anisotropy and differential rotation flows. It is shown that the kinetic formalism allows one to solve the closure problem and to consistently compute the relevant fluid fields with the inclusion of finite Larmor-radius effects. The main features of the theory and relevant applications are discussed.

Cremaschini, Claudio; Miller, John C.; Tessarotto, Massimo

2011-06-01

53

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...

Herabadi, Astrid Gisela

2003-01-01

54

Impulsive behaviour in interpersonal encounters: Associations with quarrelsomeness and agreeableness.  

Science.gov (United States)

Associations between impulsivity and interpersonal behaviours have rarely been examined, even though impulsivity may disrupt the flow of social interactions. For example, it is unknown to what extent the commonly used Barratt Impulsiveness Scale (BIS-11) predicts impulsive behaviour in social situations, and how behaving impulsively during interpersonal encounters might influence levels of quarrelsomeness and agreeableness. In this study, 48 healthy working individuals completed the BIS-11 and recorded their behaviour in social situations using event-contingent recording. Record forms included items representing quarrelsome, agreeable, and impulsive behaviours. BIS-11 motor impulsiveness scores predicted impulsive behaviour in social situations. Impulsive behaviour was associated, in different interactions, with both agreeableness and quarrelsomeness. Behaving impulsively in specific interactions was negatively associated with agreeableness in participants with higher BIS-11 motor impulsiveness and positively associated with agreeableness in participants with lower BIS-11 motor impulsiveness. Impulsive quarrelsome behaviour may cause interpersonal problems. Impulsive agreeable behaviour may have positive effects in individuals with low trait impulsivity. The idea that there are between-person differences in the effects of state impulsivity on the flow of social interaction deserves further study. PMID:24606671

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

2015-02-01

55

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

International Nuclear Information System (INIS)

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

56

Laser pulse propagation in inhomogeneous magnetoplasma channels and wakefield acceleration  

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-02-15

57

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

58

Impulsivity and personality variables in adolescents with eating disorders.  

Science.gov (United States)

Impulsivity among individuals with eating disorders (EDs) is associated with severe comorbidities and poor treatment outcome. However, research investigating the construct of impulsivity in EDs is limited. The objectives of the present study were to characterize multiple dimensions of impulsivity in adolescents with EDs; determine if differences in impulsivity were associated with ED diagnosis and/or broader personality traits; and explore the relationship between impulsivity and etiologically significant variables. Experienced clinicians from a practice-research network provided data on ED symptoms, impulsive characteristics, personality pathology, The Diagnostic and Statistical Manual of Mental Disorders comorbidity, and family and developmental history for 120 adolescent patients with EDs. Three distinct types of impulsivity were identified: general, acting out, and aggressive/destructive. The impulsivity types showed specific relationships to ED diagnosis, broader personality factors, individual histories of adverse (traumatic) events, and family histories of externalizing disorders, supporting the importance of taking, assessing, and addressing impulsivity in ED research and treatment. PMID:19363381

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

2009-04-01

59

On the impulse in impulse learning  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper experimentally investigates the nature of impulses in impulse learning. Particularly, we analyze whether positive feedback (i.e., yielding a superior payoff in a game) or negative feedback (i.e., yielding an inferior payoff in a game) leads to a systematic change in the individual choices. The results reveal that subjects predominantly learn from negative feedback.

Ding, Jieyao; Nicklisch, Andreas

2013-01-01

60

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-06-15

 
 
 
 
61

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

International Nuclear Information System (INIS)

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

62

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

63

Nerve Impulses in Plants  

Science.gov (United States)

Summarizes research done on the resting and action potential of nerve impulses, electrical excitation of nerve cells, electrical properties of Nitella, and temperature effects on action potential. (GS)

Blatt, F. J.

1974-01-01

64

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

65

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

66

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

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

Whistler waves guided by ducts with enhanced density in a collisional magnetoplasma  

Science.gov (United States)

We study the guided propagation of whistler waves along cylindrical ducts with enhanced density in a collisional magnetoplasma. It is shown that under certain conditions, the presence of comparatively small dissipative losses due to electron collisions in a plasma medium can lead to significant changes in the dispersion characteristics and field structures of whistler modes guided by such ducts compared with the case of a collisionless plasma. We present the results of numerical calculations showing such changes in the properties of whistler modes.

Es'kin, V. A.; Zaboronkova, T. M.; Kudrin, A. V.

2008-01-01

69

Vector dissipativity theory for large-scale impulsive dynamical systems  

Directory of Open Access Journals (Sweden)

Full Text Available 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 interconnections. In this paper, we develop vector dissipativity theory for large-scale impulsive dynamical systems. Specifically, using vector storage functions and vector hybrid supply rates, dissipativity properties of the composite large-scale impulsive systems are shown to be determined from the dissipativity properties of the impulsive subsystems and their interconnections. Furthermore, extended Kalman-Yakubovich-Popov conditions, in terms of the impulsive subsystem dynamics and interconnection constraints, characterizing vector dissipativeness via vector system storage functions, are derived. Finally, these results are used to develop feedback interconnection stability results for large-scale impulsive dynamical systems using vector Lyapunov functions.

Haddad Wassim M.

2004-01-01

70

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

71

Excitation of whistler waves in a collisional magnetoplasma in the presence of ducts with enhanced density  

Science.gov (United States)

A study is made of the excitation of waves in the whistler frequency range by a given ring electric current in a collisional magnetoplasma in the presence of a cylindrical duct with enhanced density. It is shown that, under certain conditions, dissipative losses due to electron collisions in plasma can lead to a substantial redistribution of the source radiation power over the spatial spectrum of the modes guided by the duct, as compared to the case of a collisionless plasma. Numerical results are presented that illustrate these changes in the excitation efficiency of whistler modes.

Es'kin, V. A.; Kudrin, A. V.

2009-09-01

72

Symmetry analysis and similarity electrostatic waves in a nonuniform dusty magnetoplasma  

International Nuclear Information System (INIS)

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

73

Symmetry analysis and similarity electrostatic waves in a nonuniform dusty magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

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

Tang Xiaoyan [Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44870 Bochum (Germany); Shukla, Padma Kant [Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44870 Bochum (Germany)

2007-06-01

74

Choice of operation conditions and plasma parameters of a magnetoplasma compressor  

International Nuclear Information System (INIS)

Results of optic and spectroscopic investigations into compression plasma flow of magnetoplasma compressor (MPC) are presented. MPC has a compact geometry with valve (pulsed) operating gas (hydrogen) feeding. Flow formation dynamics in such a MPC is studied. Rate, concentration of electrons and plasma temperature are determined. It is shown that the dependence of maximum discharge current value obtained on the mass operating gas flow rate allows one to chose the optimal conditions for MPC operation. Relatively high plasma flow parameters with the impurity quantity minimal for such systems, are relalized under the conditions mentioned

75

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.

76

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

International Nuclear Information System (INIS)

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

77

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

CERN Document Server

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

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

2012-01-01

78

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

79

Impulsive spherical gravitational waves  

CERN Document Server

Penrose's identification with warp provides the general framework for constructing the continuous form of impulsive gravitational wave metrics. We present the 2-component spinor formalism for the derivation of the full family of impulsive spherical gravitational wave metrics which brings out the power in identification with warp and leads to the simplest derivation of exact solutions. These solutions of the Einstein vacuum field equations are obtained by cutting Minkowski space into two pieces along a null cone and re-identifying them with warp which is given by an arbitrary non-linear holomorphic transformation. Using 2-component spinor techniques we construct a new metric describing an impulsive spherical gravitational wave where the vertex of the null cone lies on a world-line with constant acceleration.

Aliev, A N

2001-01-01

80

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

 
 
 
 
81

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

Science.gov (United States)

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

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

2012-09-01

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

Thermal coating development for impulse drying  

Science.gov (United States)

A plasma-sprayed coating has been developed for the heated surface of rolls used in a new energy-efficient paper drying process, known as“Impulse Drying,” which could save the US paper industry an estimated 800 million annually in reduced energy costs. Because impulse drying rolls operate at substantially higher surface temperatures than conventional drying rolls, the thermal properties of the roll surface must be carefully tailored to control energy transfer to the paper and thus prevent sheet delamination or other undesirable effects. To meet this requirement, a plasma-sprayed thermal barrier coating has been developed to control thermal mass, heat transfer, and steam infiltration. A coated test platen significantly outperformed a comparable uncoated steel platen in preliminary experiments with a heavyweight grade of paper on a laboratory-scale impulse drying simulator. Based on these results, the coating was then tested on the roll of a pilot-scale impulse dryer. Compared to conventional wet pressing, linerboard that was impulse dried with the coated test roll showed marked improvements in water removal as well as improved physical properties, such as density and specific elastic modulus. The successful prototype coating design has three plasma-sprayed layers that are deposited sequentially: a nickel alloy bond coat, a thick, 17% porous zirconia thermal barrier, and a thin, 5 to 7% porous zirconia top coat.

Lenling, W. J.; Smith, M. F.; Orloff, D. I.

1993-06-01

84

Specific Mass Estimates for A Vapor Core Reactor With MHD  

International Nuclear Information System (INIS)

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

85

Impulse abstractors with memories  

International Nuclear Information System (INIS)

The abstractor described here uses several properties of bistable circuits simultaneously in order to store, delay and connect the impulses. After considering the principle of its operation, several actual applications and some possible further uses of the apparatus are described. (author)

86

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

87

Impedance of a monopole antenna over a ground plane and immersed in a magnetoplasma  

Science.gov (United States)

A treatment of the input impedance of a monopole antenna over a ground plane covered with a magnetoplasma with any arbitrary direction of the static magnetic field is presented. The analysis is restricted to a cold plasma with uniaxial and quasi-static approximations. It has been found that for parallel and perpendicular directions of the static magnetic field with respect to the ground plane perfect mirror reflections can be obtained. For other directions of the static magnetic field, the reflection is birefringent so that the monopole impedance becomes modified over a dipole impedance. These modifications can be significant under hyperbolic plasma conditions. A short and a long monopole were considered. From laboratory measurements of a long monopole impedance, the resonance cone and the resonances corresponding to the antenna length have been observed.

Matin, M. A.; Sawaya, K.; Ishizone, T.; Mushiake, Y.

1980-05-01

88

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

International Nuclear Information System (INIS)

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

89

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.

90

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)

91

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-07-15

92

Dust kinetic Alfvén waves and streaming instability in a non-Maxwellian magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

The dust kinetic Alfvén wave (DKAW) instability is studied in a uniform dusty magnetoplasma by incorporating the superthermality effects of the electrons and perpendicularly streaming ?-distributed ions. The dispersion relation of the DKAW instability is investigated in the low-?{sub d} Lorentzian plasma limit. The solutions are analyzed for various scenarios of dusty and dusty-free plasmas. It is shown that the presence of dust particles and the cross-field superthermal ions sensibly modify the dispersion characteristics of the low-frequency DKAW. The present results are only valid for a frequency regime well below the dust cyclotron frequency. Numerical calculations are carried out for the growth rates by taking different dust parameters into account. It is found that the nonthermality is more effective for the dust kinetic Alfvén waves in the perpendicular direction as compared to the parallel one. The relevance of the results to the low-?{sub d} regions of space and astrophysical plasmas is highlighted.

Rubab, N.; Jaffer, G. [Department of Space Science, Institute of Space Technology (IST), Islamabad Expressway, Islamabad 44000 (Pakistan); Ali, S. [National Centre for Physics (NCP) at Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan)

2014-06-15

93

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

International Nuclear Information System (INIS)

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

94

Magnetoplasma waves on the surface of semiconducting nanotube with a superlattice  

International Nuclear Information System (INIS)

The spectra of plasma waves in the electron gas on the surface of semiconducting nanotube with a superlattice are considered. The external magnetic field is directed along the axis of the nanotube and the superlattice. The analysis of the intraband and interband magnetoplasma waves in the degenerate electron gas is presented in quantum and quasiclassical limits. If a number of angular motion levels are filled up then the magnetoplasmon frequencies oscillate with variation of nanotube parameters similarly to the de Haas-van Alphen oscillations. The frequencies demonstrate also the Aharonov-Bohm oscillations on magnetic flux through the nanotube cross-section. The oscillation pattern is determined by the ratio of the Fermi energy to minizone width. If this ratio is sufficiently large the beats appear in the plot of magnetoplasmon frequency as a function of tube parameters.

95

Individual differences in impulsivity predict anticipatory eye movements.  

Science.gov (United States)

Impulsivity is the tendency to act without forethought. It is a personality trait commonly used in the diagnosis of many psychiatric diseases. In clinical practice, impulsivity is estimated using written questionnaires. However, answers to questions might be subject to personal biases and misinterpretations. In order to alleviate this problem, eye movements could be used to study differences in decision processes related to impulsivity. Therefore, we investigated correlations between impulsivity scores obtained with a questionnaire in healthy subjects and characteristics of their anticipatory eye movements in a simple smooth pursuit task. Healthy subjects were asked to answer the UPPS questionnaire (Urgency Premeditation Perseverance and Sensation seeking Impulsive Behavior scale), which distinguishes four independent dimensions of impulsivity: Urgency, lack of Premeditation, lack of Perseverance, and Sensation seeking. The same subjects took part in an oculomotor task that consisted of pursuing a target that moved in a predictable direction. This task reliably evoked anticipatory saccades and smooth eye movements. We found that eye movement characteristics such as latency and velocity were significantly correlated with UPPS scores. The specific correlations between distinct UPPS factors and oculomotor anticipation parameters support the validity of the UPPS construct and corroborate neurobiological explanations for impulsivity. We suggest that the oculomotor approach of impulsivity put forth in the present study could help bridge the gap between psychiatry and physiology. PMID:22046334

Cirilli, Laetitia; de Timary, Philippe; Lefèvre, Phillipe; Missal, Marcus

2011-01-01

96

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

International Nuclear Information System (INIS)

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

97

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-08-15

98

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

International Nuclear Information System (INIS)

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

99

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

100

A model collision operator for the drift Fokker-Planck equation for applications to transport problems in magnetoplasmas  

International Nuclear Information System (INIS)

A model collision operator for the drift Fokker Planck equation for application to quiescent magnetoplasmas in presence of simmetric equilibrium hydromagnetic configurations is given. The main feature of this model, contrarily to approximate collision operators previously proposed by other authors, is that it allows to determine relevant microscopic variables by including first order corrections in terms of a suitable adimensional parameter which yields for the magnetic configuration inhomogeneities

 
 
 
 
101

Wave modes in a collision-free multi-species magnetoplasma with anisotropic background and perturbation pressures  

Science.gov (United States)

The momentum balance equations and the balance equations for the pressure tensors of a collision-free multi-species magnetoplasma are linearized and Fourier-transformed, together with Maxwell's curl equations. They are combined in an algebraic dispersion system for the electric wave vector. The vanishing determinant of this system is the dispersion equation. It is of degree 2+3s in the square of the refractive index if s is the number of different particle species.

Suchy, K.; Altman, C.

2006-02-01

102

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-10-15

103

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

International Nuclear Information System (INIS)

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

104

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

Science.gov (United States)

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

Meule, Adrian; Platte, Petra

2015-04-01

105

IMPULSE—an advanced, high performance nuclear thermal propulsion system  

Science.gov (United States)

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, Lyman J.; Disney, R. Kep; Mangus, James D.; Gunn, Stanley A.; Zweig, Herbert R.

1993-01-01

106

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

107

Impulsive phase transport  

Science.gov (United States)

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

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

1986-01-01

108

Temperament and Impulsivity Predictors of Smoking Cessation Outcomes  

Science.gov (United States)

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

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

2014-01-01

109

Impulsivity in disorders of food and drug misuse.  

Science.gov (United States)

Background. Evidence suggests some overlap between the pathological use of food and drugs, yet how impulsivity compares across these different clinical disorders remains unclear. Substance use disorders are commonly characterized by elevated impulsivity, and impulsivity subtypes may show commonalities and differences in various conditions. We hypothesized that obese subjects with binge-eating disorder (BED) and abstinent alcohol-dependent cohorts would have relatively more impulsive profiles compared to obese subjects without BED. We also predicted decision impulsivity impairment in obesity with and without BED. Method. Thirty obese subjects with BED, 30 without BED and 30 abstinent alcohol-dependent subjects and age- and gender-matched controls were tested on delay discounting (preference for a smaller immediate reward over a larger delayed reward), reflection impulsivity (rapid decision making prior to evidence accumulation) and motor response inhibition (action cancellation of a prepotent response). Results. All three groups had greater delay discounting relative to healthy volunteers. Both obese subjects without BED and alcohol-dependent subjects had impaired motor response inhibition. Only obese subjects without BED had impaired integration of available information to optimize outcomes over later trials with a cost condition. Conclusions. Delay discounting appears to be a common core impairment across disorders of food and drug intake. Unexpectedly, obese subjects without BED showed greater impulsivity than obese subjects with BED. We highlight the dissociability and heterogeneity of impulsivity subtypes and add to the understanding of neurocognitive profiles across disorders involving food and drugs. Our results have therapeutic implications suggesting that disorder-specific patterns of impulsivity could be targeted. PMID:25118940

Mole, T B; Irvine, M A; Worbe, Y; Collins, P; Mitchell, S P; Bolton, S; Harrison, N A; Robbins, T W; Voon, V

2015-03-01

110

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

111

Electric field variability and classifications of Titan's magnetoplasma environment  

Directory of Open Access Journals (Sweden)

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

C. S. Arridge

2011-07-01

112

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-04-15

113

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

International Nuclear Information System (INIS)

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

114

On the existence of compressional MHD oscillations in an inhomogeneous magnetoplasma  

International Nuclear Information System (INIS)

In a cold plasma the wave equation for solely compressional magnetic field perturbations appears to decouple in any surface orthogonal to the background magnetic field. However, the compressional fields in any two of these surfaces are related to each other by the condition that the perturbation field B be divergence-free. Hence the wave equations in these surfaces are not truly decoupled from one another. If the two solutions happen to be 'matched' (i.e. ?.b = 0) then the medium may execute a solely compressional oscillation. If the two solutions are unmatched then transverse fields must evolve. Two classes of compressional solutions are considered and a set of criteria is derived for when the medium will be able to support pure compressional field oscillations. These criteria relate to the geometry of the magnetic field and the plasma density distribution. The conditions are presented in such a manner that it is easy to see if a given magnetoplasma is able to execute either of the compressional solutions investigated. (author)

115

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

International Nuclear Information System (INIS)

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

116

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

International Nuclear Information System (INIS)

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

117

Radiation and propagation of electron waves in an arbitrary direction in a magnetoplasma  

International Nuclear Information System (INIS)

The theoretical and experimental investigation concerning the radiation and propagation of electron waves in some arbitrary direction from the point source in magnetoplasma were performed. The analyses based on the fluid and the kinetic theories were carried out, and comparison with experimental results was made. The characteristic feature of radiation in the anisotropic plasma changes largely at the boundary of the electron plasma frequency f sub (p) and the electron cyclotron frequency f sub (c). In the frequency region between f sub (p) and f sub (c), no serious difference between the fluid and the kinetic theories was found in the ray velocity, and the explanation for wave potential by the kinetic theory shows better agreement with the experimental results. When the frequency of the propagating waves is larger than f sub (c), the static electron cyclotron mode is seen as well as the electron plasma mode. The cyclotron mode waves propagate in wide range of angle, and the ray velocity surface is almost parallel to the magnetic field. These facts were partially confirmed by experimental results. (Kato, T.)

118

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

International Nuclear Information System (INIS)

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

119

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

120

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-07-15

 
 
 
 
121

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

122

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

123

Electron thermal effect on linear and nonlinear coupled Shukla-Varma and convective cell modes in dust-contaminated magnetoplasma  

International Nuclear Information System (INIS)

Linear and nonlinear properties of coupled Shukla-Varma (SV) and convective cell modes in the presence of electron thermal effects are studied in a nonuniform magnetoplasma composed of electrons, ions, and extremely massive and negatively charged immobile dust grains. In the linear case, the modified dispersion relation is given and, in the nonlinear case, stationary solutions of the nonlinear equations that govern the dynamics of coupled SV and convective cell modes are obtained. It is found that electrostatic dipolar and vortex street type solutions can appear in such a plasma. The relevance of the present investigation with regard to the Earth's mesosphere as well as in ionospheric plasmas is also pointed out.

124

Impulsive differential inclusions with constrains  

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In the paper, we study weak invariance of differential inclusions with non-fixed time impulses under compactness type assumptions. When the right-hand side is one sided Lipschitz an extension of the well known relaxation theorem is proved. In this case also necessary and sufficient condition for strong invariance of upper semi continuous systems are obtained. Some properties of the solution set of impulsive system (without constrains) in appropriate topology are investigated.

Tzanko Donchev

2006-01-01

125

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

126

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

127

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

Science.gov (United States)

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

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

2013-01-01

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

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

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

Science.gov (United States)

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

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

2014-11-01

131

Impulsive Neural Networks Algorithm Based on the Artificial Genome Model  

Directory of Open Access Journals (Sweden)

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

Yuan Gao

2014-05-01

132

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 circ...

Janaki, S.; Dr. Siva Yellampalli,

2013-01-01

133

Solar flares - The impulsive phase  

Science.gov (United States)

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

Dennis, Brian R.; Schwartz, Richard A.

1989-01-01

134

Sex differences in impulsivity: a meta-analysis.  

Science.gov (United States)

Men are overrepresented in socially problematic behaviors, such as aggression and criminal behavior, which have been linked to impulsivity. Our review of impulsivity is organized around the tripartite theoretical distinction between reward hypersensitivity, punishment hyposensitivity, and inadequate effortful control. Drawing on evolutionary, criminological, developmental, and personality theories, we predicted that sex differences would be most pronounced in risky activities with men demonstrating greater sensation seeking, greater reward sensitivity, and lower punishment sensitivity. We predicted a small female advantage in effortful control. We analyzed 741 effect sizes from 277 studies, including psychometric and behavioral measures. Women were consistently more punishment sensitive (d = -0.33), but men did not show greater reward sensitivity (d = 0.01). Men showed significantly higher sensation seeking on questionnaire measures (d = 0.41) and on a behavioral risk-taking task (d = 0.36). Questionnaire measures of deficits in effortful control showed a very modest effect size in the male direction (d = 0.08). Sex differences were not found on delay discounting or executive function tasks. The results indicate a stronger sex difference in motivational rather than effortful or executive forms of behavior control. Specifically, they support evolutionary and biological theories of risk taking predicated on sex differences in punishment sensitivity. A clearer understanding of sex differences in impulsivity depends upon recognizing important distinctions between sensation seeking and impulsivity, between executive and effortful forms of control, and between impulsivity as a deficit and as a trait. PMID:21219058

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

2011-01-01

135

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 R(2) = 0.23, F(1,16) = 5.83, P = 0.03] and improved problem solving on the One Touch Stockings of Cambridge [adjusted R(2) = 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. PMID:24893708

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

2014-07-01

136

Commentary on Hyperkinetic Impulse Disorder  

Science.gov (United States)

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

Barkley, Russell A.

2011-01-01

137

Colliding impulsive waves in succession  

International Nuclear Information System (INIS)

We formulate the initial-value problem for two colliding trains of impulsive gravitational waves. In the absence of a global, exact solution we show that in a region lying between the singularity u2+v2=1 and the wave trains, the solution is still the well-known Khan-Penrose solution

138

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 ...

Tsai Chen

2008-01-01

139

Brain circuitry of compulsivity and impulsivity.  

Science.gov (United States)

Impulsivity and compulsivity have been considered opposite poles of a continuous spectrum, but their relationship appears to be more complex. Disorders characterized by impulsivity often have features of compulsivity and vice versa. The overlaps of the constructs of compulsivity and impulsivity warrant additional investigation, not only to identify the similarities and differences, but also to examine the implications for prevention and treatment strategies of both compulsive and impulsive behaviors. PMID:23659364

Grant, Jon E; Kim, Suck Won

2014-02-01

140

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

 
 
 
 
141

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

142

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)

143

Investigation of the properties of electrostatic IA solitary wave structures in negative ion magneto-plasmas with superthermal electrons  

Science.gov (United States)

A rigorous theoretical investigation is carried out in analyzing the excitation of electrostatic ion acoustic (IA) solitary wave (SW) structures in two dimensional negative ion magneto-plasmas with superthermal electrons (following ? type distribution). The Zakharov-Kuznetsov (ZK) equation is derived by employing the well known reductive perturbation method, and the analytical solution of ZK equation assists to find out the SW profiles along with their properties. The consequences of different plasma parameters (regarding our considered plasma system) variation on SW structures has been studied. It is found that magnetic field intensity, superthermal parameter ? and temperature of positive and negative ions as well as their densities significantly modify the basic characteristics (amplitude, width, etc.) of the SW waves. A comparison of the SW structures is also presented when the electrons are Maxwellian to when they are superthermal. The relevance of the findings of this work with astrophysical plasmas is briefly pointed out.

Hussain, S.; Ali Shan, S.; Akhtar, N.; Masud, M. M.

2014-08-01

144

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

145

Trait impulsivity and increased pre-attentional sensitivity to intense stimuli in bipolar disorder and controls.  

Science.gov (United States)

Impulsivity and sensation seeking are stimulus-oriented traits. Because they differ in degree of intention and planning, they may have distinct neurophysiological mechanisms. Impulsivity is prominent in bipolar disorder, and may be related to pre-attentional information filtering and stimulus-orientation. We investigated specificity of relationships between impulsivity and sensitivity to stimulus intensity in bipolar disorder and controls, using intensity-sensitivity of auditory evoked potentials. Seventy-six subjects (37 healthy controls, 39 with bipolar disorder) were administered an intensity-sensitivity paradigm. Additional measures included Barratt Impulsiveness Scale (BIS-11) and Eysenck Impulsivity and Venturesomeness scores. State-dependent rapid-response impulsivity was measured using the Immediate Memory Task. Intensity-sensitivities of the auditory evoked P1N1, N1P2, P1, N1, and P2 potentials were assessed as the slope of amplitude relative to loudness. Analyses used general linear models (GLM) with impulsivity-related measures as dependent variables and age, gender, education, and diagnosis as dependent variables. BIS-11 total, motor, and attentional impulsivity scores correlated positively with pre-attentional N1 and P1N1 intensity-sensitivity slopes in bipolar disorder, but not in controls. BIS-11 nonplanning and Eysenck Venturesomeness scores did not correlate with intensity-sensitivity. Intensity-sensitivity slopes did not correlate with rapid-response impulsivity. Correlations between N1 or P1N1 slopes and BIS-11 scores in bipolar disorder were not affected by age, education, WAIS, treatment, symptoms, or gender. Trait impulsivity in bipolar disorder may be related to poorly modulated stimulus-driven late pre-attentional responses to stimuli, potentially resulting in exaggerated responses to intense stimuli even before conscious awareness. Components of trait impulsivity are physiologically heterogenous relative to intensity-sensitivity. PMID:25455512

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

2014-10-12

146

Scale model ultrawideband impulse radar  

Science.gov (United States)

The Transient Electromagnetic Scattering Laboratory (TESL) is described which employs a unique dual-channel ultra-wideband impulsive illuminating source. This is a free-field facility where targets are suspended within an anechoic chamber. A highly coherent primal step pulse is amplified by two GaAs wideband power amplifiers having complementary passbands which feed individual wideband horn antennas. This yields an effective 1 - 12 GHz impulse bandwidth. A high speed digital processing oscilloscope samples the output of a single receiving horn. The TESL has facilitated research into radar target identification using complex natural resonances. Theory and operational characteristics of the facility are discussed and technical improvements are described which have yielded significant improvement in both the effective bandwidth and the signal-to-noise ratio of transient scattering measurements. Experimental validations are shown which illustrate the level of fidelity attainable and consideration is given to recent enhancements, including an increase of measurement bandwidth to 50 GHz.

Morgan, Michael A.

1993-05-01

147

FM over impulse radio UWB  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Recent regulatory action provided access to large chunks of spectrum for low spectral power density ultra-wideband communication and sensing devices, yet use of this spectrum currently lags behind expectations. The authors propose a simple migration path suitable for low-cost analog audio and video distribution. It uses FM modulation of the clock signal to an impulse radio pulse generator and a simple receiver based on a rectifier or squaring device which retrieves the FM modulated signal. Us...

Schleicher, Bernd; Ghaleb, Hatem; Trasser, Andreas; Schumacher, Hermann

2009-01-01

148

Managing Impulsive Interference in Impulse Radio UWB Networks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2007-01-01

149

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.

2011-08-01

150

A Review of Impulse Buying Behavior  

Directory of Open Access Journals (Sweden)

Full Text Available Researchers and Practitioners have been interested in the field of impulse buying for the past sixty years (Clover,1950; Stern, 1962; Rook, 1987; Peck and Childers, 2006; Chang et.al, 2011. The purpose of this paper is toprovide a detailed account of the impulse buying behavior by compiling the various research works literature inthe field of Retailing and Consumer Behavior. It gives a broad overview of the impulse buying construct and thevarious behavior related aspects. A wide range of journal databases and books were referred to review the worksof various researchers. The content analysis of the various research works led to the classification of literatureinto different factors influencing impulse buying and further development of research framework. The multipleaspects of the subject are categorized for future research works in the area of impulse buying with thesuggestions. The paper will be useful for marketing practitioners and researchers towards comprehensiveunderstanding of the consumer’s impulsiveness.  

G. Muruganantham

2013-04-01

151

Impulsive differential inclusions a fixed point approach  

CERN Document Server

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

Ouahab, Abdelghani; Henderson, Johnny

2013-01-01

152

On a SIS model with impulsive effects  

CERN Document Server

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

De la Sen, M; Alonso-Quesada, S

2011-01-01

153

Impulsive synchronization of Chen's hyperchaotic system  

International Nuclear Information System (INIS)

In this Letter the impulsive synchronization of the Chen's hyperchaotic systems is discussed. Some new and sufficient conditions on varying impulsive distance are established in order to guarantee the synchronizabillity of the systems using the synchronization method. In particular, some simple conditions are derived in synchronizing the systems by equal impulsive distances. Two illustrative examples are provided to show the feasibility and the effectiveness of the proposed method. The boundaries of the stable regions are also estimated

154

Impulsivity in restrained eaters: emotional and external eating are associated with attentional and motor impulsivity.  

Science.gov (United States)

The current study examined the relationships of motor, nonplanning, and attentional impulsivity to external and emotional eating among restrained eaters. Data were collected from a female college sample of restrained eaters (N=90). Aspects of impulsivity and disordered eating were assessed using the Barratt Impulsiveness Scale, Version 11, the Attentional Control Scale and the Dutch Eating Behavior Questionnaire. Significant correlations emerged between eating disturbances and different types of impulsivity. The results indicated that restrained eating is associated with motor and attentional forms of impulsivity. Emotional eating appears to be linked to both attentional and motor impulsivity whereas external eating seems to be linked only to motor impulsivity. Future studies should explore which aspects of disinhibited eating among restrained eaters are best predicted by a tendency to act impulsively. PMID:22751274

Ebneter, D; Latner, J; Rosewall, J; Chisholm, A

2012-03-01

155

Saturation of Richtmyer's impulsive model  

International Nuclear Information System (INIS)

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

156

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

157

Impulsive synchronization of networked nonlinear dynamical systems  

Energy Technology Data Exchange (ETDEWEB)

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

Jiang Haibo, E-mail: yctcjhb@gmail.co [Faculty of Science, Jiangsu University, Zhenjiang 212013 (China); School of Mathematics, Yancheng Teachers University, Yancheng 224051 (China); Bi Qinsheng [Faculty of Science, Jiangsu University, Zhenjiang 212013 (China)

2010-06-14

158

Impulsive synchronization of networked nonlinear dynamical systems  

International Nuclear Information System (INIS)

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

159

Compulsivity, impulsivity, and the DSM-5 process.  

Science.gov (United States)

Compulsivity and impulsivity are cross-cutting, dimensional symptom domains that span traditional diagnostic boundaries. We examine compulsivity and impulsivity from several perspectives and present implications for these symptom domains as they relate to classification. We describe compulsivity and impulsivity as general concepts, from the perspectives of the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) Research Planning Agenda, and from the DSM-5 workgroups, literature reviews, and field trials. Finally, we detail alternative modes of classification for compulsivity and impulsivity in line with the Research Domain Criteria (RDoC) and International Classification of Diseases (ICD-11). PMID:24229702

Berlin, Gregory S; Hollander, Eric

2014-02-01

160

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...

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

2011-01-01

 
 
 
 
161

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Leeman, Robert F.; Potenza, Marc N.

2011-01-01

162

Impulse responses in bacterial chemotaxis.  

Science.gov (United States)

The chemotactic behavior of Escherichia coli has been studied by exposing cells tethered by a single flagellum to pulses of chemicals delivered iontophoretically. Normally, wild-type cells spin alternately clockwise and counterclockwise, changing their direction on the average approximately once per second. When cells were exposed to a very brief diffusive wave of attractant, the probability of spinning counterclockwise quickly peaked, then fell below the prestimulus value, returning to baseline within a few seconds; repellent responses were similar but inverted. The width of the response indicates that cells integrate sensory inputs over a period of seconds, while the biphasic character implies that they also take time derivatives of these inputs. The sensory system is maximally tuned to concentration changes that occur over a span of approximately 2 sec, an interval over which changes normally occur when cells swim in spatial gradients; it is optimized to extract information from signals subject to statistical fluctuation. Impulse responses of cells defective in methylation were similar to those of wild-type cells, but did not fall as far below the baseline, indicating a partial defect in adaptation. Impulse responses of cheZ mutants were aberrant, indicating a serious defect in excitation. PMID:6760985

Block, S M; Segall, J E; Berg, H C

1982-11-01

163

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...

Meisal, Kjetil

2005-01-01

164

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

165

Hyperkinetic Impulse Disorder in Children's Behavior Problems  

Science.gov (United States)

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

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

2011-01-01

166

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

International Nuclear Information System (INIS)

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

167

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

168

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)

169

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-09-15

170

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

171

Bolometric detection of magnetoplasma resonances in microwave absorption by two-dimensional electron systems based on doping layer conductivity measurements in GaAs/AlGaAs heterostructures  

Science.gov (United States)

We have implemented a new bolometric method to detect resonances in magneto-absorption of microwave radiation by two-dimensional electron systems (2DES) in selectively doped GaAs/AlGaAs heterostructures. Radiation is absorbed by the 2DES and the thermally activated conductivity of the doping layer supplying electrons to the 2DES serves as a thermometer. The resonant absorption brought about by excitation of the confined magnetoplasma modes appears as peaks in the magnetic field dependence of the low-frequency impedance measured between the Schottky gate and 2DES.

Dorozhkin, S. I.; Sychev, D. V.; Kapustin, A. A.

2014-11-01

172

Spin Stabilized Impulsively Controlled Missile (SSICM)  

Science.gov (United States)

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

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

1985-12-01

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...

Menzer, Fritz; Faller, Christof

2008-01-01

174

Restoration of Images Corrupted by Impulse Noise and Mixed Gaussian Impulse Noise using Blind Inpainting  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This article studies the problem of image restoration of observed images corrupted by impulse noise and mixed Gaussian impulse noise. Since the pixels damaged by impulse noise contain no information about the true image, how to find this set correctly is a very important problem. We propose two methods based on blind inpainting and $\\ell_0$ minimization that can simultaneously find the damaged pixels and restore the image. By iteratively restoring the image and updating the ...

Yan, Ming

2013-01-01

175

Scramjet testing in impulse facilities  

Science.gov (United States)

The use of impulse facilities for gas dynamic experimentation on scramjets at high stagnation enthalpies is discussed. It is seen that, although such facilities will produce adequate stagnation enthalpies, it is necessary to compromise somewhat on the requirements for simulating test section densities, in order to allow realistic operating pressure levels. The shock tunnel and the expansion tube are briefly described, before focusing on operation of the reflected shock tunnel. It is shown that test times and flow starting times are such as to allow testing with models of reasonable size, provided that large regions of flow recirculation do not exist. Some examples of experimental scramjet studies, conducted in a reflected shock tunnel, are presented, demonstrating that the reflected shock tunnel is suitable for basic studies of scramjet flow processes. Provided that the effective enhancement of fuel calorific value by free stream 'freezing' of oxygen in the shock tunnel nozzle expansion does not prove to be an insuperable obstacle, the reflected shock tunnel may be expected to provide realistic simulation of scramjet flows up to speeds approaching earth orbital velocity.

Stalker, R. J.; Morgan, R. G.

1987-01-01

176

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)

177

Modification of Impulsive Visual Discrimination Performance  

Science.gov (United States)

Investigated was whether the visual discrimination performances of 16 primary-grade, conceptually impulsive school children could be modified by altering the directions and administration procedures of a visual discrimination match-to-sample test. (Author/JYC)

Margolis, Howard; And Others

1978-01-01

178

Detecting Impulses in Mechanical Signals by Wavelets  

Directory of Open Access Journals (Sweden)

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

Yang W-X

2004-01-01

179

Stochastic impulsive control for the stabilization of Lorenz system  

International Nuclear Information System (INIS)

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

180

Extending the impulse response in order to reduce errors due to impulse noise and signal fading  

Science.gov (United States)

A finite impulse response (FIR) digital smearing filter was designed to produce maximum intersymbol interference and maximum extension of the impulse response of the signal in a noiseless binary channel. A matched FIR desmearing filter at the receiver then reduced the intersymbol interference to zero. Signal fades were simulated by means of 100 percent signal blockage in the channel. Smearing and desmearing filters of length 256, 512, and 1024 were used for these simulations. Results indicate that impulse response extension by means of bit smearing appears to be a useful technique for correcting errors due to impulse noise or signal fading in a binary channel.

Webb, Joseph A.; Rolls, Andrew J.; Sirisena, H. R.

1988-01-01

 
 
 
 
181

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)

182

Autocorrélation interférométrique monocoup d'impulsions femtosecondes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nous présentons dans cet article une nouvelle méthode de caractérisation d'impulsions laser femtosecondes. Celle-ci est basée sur l'analyse du profil spatial du faisceau produit par doublage de fréquence lorsque deux impulsions se croisent dans un cristal non linéaire. Si ce profil est enregistré avec une précision interférométrique, la fonction d'autocorrélation est modulée par un système de franges. Cette fonction d'autocorrélation interférométrique monocoup permet d'obtenir...

Salin, Franck; Georges, Patrick; Le Saux, Gilles; Roger, Ge?rard; Brun, Alain

1987-01-01

183

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

International Nuclear Information System (INIS)

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

184

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

185

Impulsivity and decision making in alcohol-addicted individuals [Impulsywno?? a podejmowanie decyzji u osób uzale?nionych od alkoholu  

Directory of Open Access Journals (Sweden)

Full Text Available Decision making processes are the research problem, that has been increasingly undertaken. Alcohol addiction is a disease associated with unfavorable decision making, in spite of its negative consequences. Impulsivity plays an important role in alcoholics’ decision making. It can be understood in terms of behavioral and/or cognitive flexibility disorders, that manifest in cognitive function disorders, making it difficult or even impossible to quickly and adequately assess the situation and to adjust behavior according to its requirements. Neurobiological and genetic research indicate the existing relationship between impulsivity and certain genetic predisposition. In alcohol addicts, impulsivity can be understood also in terms of specific personality traits, e.g. novelty seeking according to the theory of Cloninger. Although the concept of impulsivity itself has been the main topic of many studies, not many of them concern also decision making processes. In studies concerning alcoholics’ decision making, the relationship between this processes and behavioral impulsivity defined in many different ways, has been noticed. Some of these works define unfavorable decision making processes itself as a feature of impulsivity. Based on the results of theoretical works and research studies, it seems that it would be worth to define more precisely the concept of impulsivity, in order to determine its effect on decision making. The assessment of whether - and to what extent - the two variables (impulsivity and decision making can be considered as separate should also be taken into account.

Ka?wa, Agnieszka

2013-04-01

186

Restrained eaters consume more food only if they are impulsive and male.  

Science.gov (United States)

This study utilised the preload paradigm to evaluate whether dietary restraint, impulsivity, or their interaction significantly predicts heightened food consumption among male and/or female participants. Following a high calorie preload, 79 participants aged 18 to 40 (53 females and 26 males) completed a deceptive taste test and questionnaires measuring restraint and impulsivity levels. A series of hierarchical regressions were run, controlling for self-rated hunger levels. A significant negative association between level of restraint and food consumption post-preload was found for males, but this relationship was not significant for female participants. The hypothesis that impulsivity would directly predict heightened food consumption was not supported for either gender. However, impulsivity was found to significantly moderate the relationship between restraint and food intake in the male sample, but not the female, providing partial support for this hypothesis. Potential reasons for this gender-specific interaction effect of impulsivity and restraint for food consumption are discussed. More broadly, present findings highlight the need for further consideration of the role of impulsivity in undermining food intake of restrained eaters. Future research should also consider how preload effects may differ across gender. PMID:25218355

Greenwood, J; Broadbent, J; Fuller-Tyszkiewicz, M

2014-12-01

187

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

Science.gov (United States)

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

Delgado-Rico, Elena; Río-Valle, Jacqueline S; González-Jiménez, Emilio; Campoy, Cristina; Verdejo-García, Antonio

2012-08-01

188

The effects of lactation on impulsive behavior in vasopressin-deficient Brattleboro rats.  

Science.gov (United States)

Vasopressin (AVP)-deficient Brattleboro rats develop a specific behavioral profile, which-among other things-include altered cognitive performance. This profile is markedly affected by alterations in neuroendocrine state of the animal such as during lactation. Given the links between AVP and cognition we hypothesized that AVP deficiency may lead to changes in impulsivity that is under cognitive control and the changes might be altered by lactation. Comparing virgin and lactating AVP-deficient female Brattleboro rats to their respective controls, we assessed the putative lactation-dependent effects of AVP deficiency on impulsivity in the delay discounting paradigm. Furthermore, to investigate the basis of such effects, we assessed possible interactions of AVP deficiency with GABAergic and serotonergic signaling and stress axis activity, systems playing important roles in impulse control. Our results showed that impulsivity was unaltered by AVP deficiency in virgin rats. In contrast a lactation-induced increase in impulsivity was abolished by AVP deficiency in lactating females. We also found that chlordiazepoxide-induced facilitation of GABAergic and imipramine-induced enhancement of serotonergic activity in virgins led to increased and decreased impulsivity, respectively. In contrast, during lactation these effects were visible only in AVP-deficient rats. These rats also exhibited increased stress axis activity compared to virgin animals, an effect that was abolished by AVP deficiency. Taken together, AVP appears to play a role in the regulation of impulsivity exclusively during lactation: it has an impulsivity increasing effect which is potentially mediated via stress axis-dependent mechanisms and fine-tuning of GABAergic and serotonergic function. PMID:25117459

Aliczki, Mano; Fodor, Anna; Balogh, Zoltan; Haller, Jozsef; Zelena, Dora

2014-08-01

189

Associations among types of impulsivity, substance use problems and Neurexin-3 polymorphisms  

Science.gov (United States)

Background Some of the genetic vulnerability for addiction may be mediated by impulsivity. This study investigated relationships among impulsivity, substance use problems and six neurexin-3 (NRXN3) polymorphisms. Neurexins (NRXNs) are presynaptic transmembrane proteins that play a role in the development and function of synapses. Methods Impulsivity was assessed with the Barratt Impulsiveness Scale Version 11 (BIS-11), the Boredom Proneness Scale (BPS) and the TIME paradigm; alcohol problems with the Michigan Alcoholism Screening Test (MAST); drug problems with the Drug Abuse Screening Test (DAST-20); and regular tobacco use with a single question. Participants (N = 439 Caucasians, 64.7% female) donated buccal cells for genotyping. Six NRXN3 polymorphisms were genotyped: rs983795, rs11624704, rs917906, rs1004212, rs10146997 and rs8019381. A dual luciferase assay was conducted to determine whether allelic variation at rs917906 regulated gene expression. Results In general, impulsivity was significantly higher in those who regularly used tobacco and/or had alcohol or drug problems. In men, there were modest associations between rs11624704 and attentional impulsivity (p = .005) and between rs1004212 and alcohol problems (p = .009). In women, there were weak associations between rs10146997 and TIME estimation (p = .03); and between rs1004212 and drug problems (p = .03). The dual luciferase assay indicated that C and T alleles of rs917906 did not differentially regulate gene expression in vitro. Conclusions Associations between impulsivity, substance use problems and polymorphisms in NRXN3 may be gender specific. Impulsivity is associated with substance use problems and may provide a useful intermediate phenotype for addiction. PMID:21676558

Stoltenberg, Scott F.; Lehmann, Melissa K.; Christ, Christa C.; Hersrud, Samantha L.; Davies, Gareth E.

2011-01-01

190

Serotonin system gene polymorphisms are associated with impulsivity in a context dependent manner.  

Science.gov (United States)

Impulsivity is a risk factor for adverse outcomes and characterizes several psychiatric disorders and risk for suicide. There is strong evidence that genetic variation influences individual differences in impulsivity, but the details are not yet understood. There is growing interest in better understanding the context dependency of genetic effects that is reflected in studies examining gender specificity, gene×environment interaction and epistasis (gene-gene interaction). In a cross-sectional study we examined whether polymorphisms in six serotonin system candidate genes and the experience of early life trauma (age 0-12) were associated with individual differences in impulsivity in a non-clinical sample of Caucasian university students (N=424). We specifically tested potential gender specific, gene-gene, and gene×environment (early life trauma) effects. In our main analyses with Barratt Impulsiveness Scale (BIS-11) total score, there were significant (i.e. pHTR1B (rs6296) and rs6313 genotypes. Our results strongly support the explicit investigation of context dependent genetic effects on impulsivity and may help to resolve some of the conflicting reports in the literature. PMID:22735397

Stoltenberg, Scott F; Christ, Christa C; Highland, Krista B

2012-10-01

191

Environmental Rearing Effects on Impulsivity and Reward Sensitivity  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2013-01-01

192

Plasma properties in high power impulse magnetron sputtering  

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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...

Lundin, Daniel

2008-01-01

193

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

Science.gov (United States)

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

Straus, M A; Mouradian, V E

1998-01-01

194

Stall Control Simulation with an Impulse Jet  

Science.gov (United States)

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

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

2010-11-01

195

Underground scanning with an impulse radar  

International Nuclear Information System (INIS)

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

196

Spray deposition using impulse atomization technique  

International Nuclear Information System (INIS)

A novel technique, impulse atomization, has been used for spray deposition. This single fluid atomization technique leads to different spray characteristics and impact conditions of the droplets compared to gas atomization technique which is the common technique used for spray deposition. Deposition experiments with a Cu-6Sn alloy were conducted to evaluate the appropriateness of impulse atomization to produce dense material. Based on these experiments, a model has been developed to simulate the thermal history and the local solidification rates of the deposited material. A numerical study shows how different cooling conditions affect the solidification rate of the material

197

Impulsive synchronization of different hyperchaotic (chaotic) systems  

Energy Technology Data Exchange (ETDEWEB)

The impulsive synchronization has been employed to synchronize two different hyperchaotic (chaotic) systems. Conditions on impulse distances are given in order to obtain stable synchronization in the nominal case and robust stability in the case that we experience uncertainties in the systems dynamic and/or measurement noise. Under the given conditions, it is guaranteed that the error dynamics is asymptotically stable for the nominal case and convergent to a predetermined level for uncertain and/or noisy circumstances. Computer simulations are provided to assess results of the given theorems in the paper.

Haeri, Mohammad [Advance Control System Laboratory, Electrical Engineering Department, Sharif University of Technology, Tehran (Iran, Islamic Republic of)], E-mail: haeri@sina.sharif.edu; Dehghani, Mahsa [Advance Control System Laboratory, Electrical Engineering Department, Sharif University of Technology, Tehran (Iran, Islamic Republic of)

2008-10-15

198

Impulsive synchronization of different hyperchaotic (chaotic) systems  

International Nuclear Information System (INIS)

The impulsive synchronization has been employed to synchronize two different hyperchaotic (chaotic) systems. Conditions on impulse distances are given in order to obtain stable synchronization in the nominal case and robust stability in the case that we experience uncertainties in the systems dynamic and/or measurement noise. Under the given conditions, it is guaranteed that the error dynamics is asymptotically stable for the nominal case and convergent to a predetermined level for uncertain and/or noisy circumstances. Computer simulations are provided to assess results of the given theorems in the paper

199

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

Directory of Open Access Journals (Sweden)

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

Saee Paliwal

2014-07-01

200

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

Science.gov (United States)

Impulsivity plays a key role in decision-making under uncertainty. It is a significant contributor to problem and pathological gambling (PG). Standard assessments of impulsivity by questionnaires, however, have various limitations, partly because impulsivity is a broad, multi-faceted concept. What remains unclear is which of these facets contribute to shaping gambling behavior. In the present study, we investigated impulsivity as expressed in a gambling setting by applying computational modeling to data from 47 healthy male volunteers who played a realistic, virtual slot-machine gambling task. Behaviorally, we found that impulsivity, as measured independently by the 11th revision of the Barratt Impulsiveness Scale (BIS-11), correlated significantly with an aggregate read-out of the following gambling responses: bet increases (BIs), machines switches (MS), casino switches (CS), and double-ups (DUs). Using model comparison, we compared a set of hierarchical Bayesian belief-updating models, i.e., the Hierarchical Gaussian Filter (HGF) and Rescorla-Wagner reinforcement learning (RL) models, with regard to how well they explained different aspects of the behavioral data. We then examined the construct validity of our winning models with multiple regression, relating subject-specific model parameter estimates to the individual BIS-11 total scores. In the most predictive model (a three-level HGF), the two free parameters encoded uncertainty-dependent mechanisms of belief updates and significantly explained BIS-11 variance across subjects. Furthermore, in this model, decision noise was a function of trial-wise uncertainty about winning probability. Collectively, our results provide a proof of concept that hierarchical Bayesian models can characterize the decision-making mechanisms linked to the impulsive traits of an individual. These novel indices of gambling mechanisms unmasked during actual play may be useful for online prevention measures for at-risk players and future assessments of PG. PMID:25071497

Paliwal, Saee; Petzschner, Frederike H; Schmitz, Anna Katharina; Tittgemeyer, Marc; Stephan, Klaas E

2014-01-01

 
 
 
 
201

State Estimation for the VASIMR Plasma Engine  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2008-01-01

202

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1998-03-01

203

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

204

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

CERN Document Server

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

Zhang, Hantian

2014-01-01

205

Improvement of impulse breakdown strength of an XLPE cable by modifing semiconducting layer  

Science.gov (United States)

A technique was investigated which reduces insulation thickness by improving breakdown strength of XLPE (cross-linked polyethylene) cables, using additives to improve interfaces of semiconducting layers, in order to restrain construction cost. Miniature model cables of 1mm insulation thick, 2mm diameter of inner semiconducting layer were manufactured. An additive was included in the semiconducting layer of each miniature cable to improve the interface with the insulating layer. The strength of dielectric breakdown was measured by testing of the impulsive pressure with lightning. The results of the impulse breakdown test show a rise in breakdown strength, indicating the effective function to make interface defects harmless. Based on the results of a previous report, a specific kind of additive which has an excellent function to improve both ac and impulse breakdown strength was selected. Additives used in this test are mainly nonionic surface active agents such as polyglyceric fatty acid esters.

Hozumi, N.; Okamoto, T.; Ishida, M.

1988-09-01

206

Mean – Median Filtering For Impulsive Noise Removal  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of this paper is a new Mean- Median filtering for denoising extremely corrupted images by impulsive noise. Whenever an image is converted from one form to another, some of degradation occurs at the output. Improvement in the quality of these degraded images can be achieved by the application of Restoration and /or Enhancement techniques. Noise removing is one of the categories of Enhancement. Removing noise from the original signal is still a challenging problem. Mean filtering fails to effectively remove heavy tailed noise & performance poorly in the presence of signal dependent noise. The successes of median filters are edge preservation and efficient attenuation of impulsive noise. An important shortcoming of the median filter is that the output is one of the samples in the input window. Based on this mixture distributions are proposed to effectively remove impulsive noise characteristics. Finally, the results of comparative analysis of mean-median algorithm with mean, median filters for impulsive noise removal show a high efficiency of this approach relatively to other ones.

N.Sakthivel

2014-04-01

207

Impulse Plasma In Surface Engineering - a review  

Science.gov (United States)

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

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

2014-11-01

208

Reflection-Impulsivity and Social Reasoning.  

Science.gov (United States)

The major purpose of this study was to assess the degree to which cognitive style, as indexed by the Matching Familiar Figures Test (MFFT), is related to the way in which children respond to problems with social or interpersonal content. Fifty-two reflective and 64 impulsive first- and second-grade boys were presented with a number of stories in…

Peters, R. DeV.; Bernfeld, Gary A.

209

Integral manifolds of impulsive differential equations  

Directory of Open Access Journals (Sweden)

Full Text Available The present paper is concerned with the existence of integral manifolds of impulsive differential equations as t?+?. Under the assumption of exponential trichotomy on the linear part of the right-hand side of the equation, it is proved that if the nonlinear perturbation is small enough, then there exist integral manifolds as t?+? for the perturbed equations.

D. D. Bainov

1992-01-01

210

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

211

Impulsivity and Personality Variables in Adolescents with Eating Disorders  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2009-01-01

212

PERFORMANCE OF IMPULSE NOISE DETECTION METHODS IN REMOTE SENSING IMAGES  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Remote sensing (RS) images are affected by different types of noises like Gaussian noise, speckle noise and impulse noise. These noises are introduced into the RS images during acquisition or transmission process. The main challenge in impulse noise removal is to suppress the noise as well as to preserve the details (edges). Removal ofthe impulse noise is done by two stages: detection of noisy pixel and replacement of that pixel. Detecting and Removing or reducing impulse noise is a very acti...

Mrs.V.RADHIKA,; Padmavathi, Dr G.

2010-01-01

213

Oscillation for higher order nonlinear ordinary differential equations with impulses  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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; Weizhen Feng

2006-01-01

214

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

215

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

216

Measuring Impulsivity in Adolescents with Serious Substance and Conduct Problems  

Science.gov (United States)

Adolescents with substance use and conduct disorders have high rates of aggression and attention deficit hyperactivity disorder (ADHD), all of which have been characterized in part by impulsivity. Developing measures that capture impulsivity behaviorally and correlate with self-reported impulsivity has been difficult. One promising behavioral…

Thompson, Laetitia L.; Whitmore, Elizabeth A.; Raymond, Kristen M.; Crowley, Thomas J.

2006-01-01

217

Flare kernel in the impulsive phase  

International Nuclear Information System (INIS)

The impulsive phase of a flare is characterized by impulsive bursts of x-ray and microwave radiation, related to impulsive footpoint heating up to 50 or 60 MK, by upward gas velocities (150 to 400 km/sec) and by a gradual increase of the flare's thermal energy content. These phenomena, as well as non-thermal effects, are all related to the impulsive energy injection into the flare. The available observations are also quantitatively consistent with a model in which energy is injected into the flare by beams of energetic electrons, causing ablation of chromospheric gas, followed by convective rise of gas. Thus, a hole is burned into the chromosphere; at the end of impulsive phase of an average flare the lower part of that hole is situated about 1800 km above the photosphere. H alpha and other optical and UV line emission is radiated by a thin layer (approx. 20 km) at the bottom of the flare kernel. The upward rising and outward streaming gas cools down by conduction in about 45 s. The non-thermal effects in the initial phase are due to curtailing of the energy distribution function by escape of energetic electrons. The single flux tube model of a flare does not fit with these observations; instead we propose the spaghetti-bundle model. Microwave and gamma-ray observations suggest the occurrence of dense flare knots of approx. 800 km diameter, and of high temperature. Future observations should concentrate on locating the microwave/gamma-ray sources, and on determining the kernel's fine structure and the related multi-loop structure of the flaring area

218

Low frequency electrostatic waves in weakly inhomogeneous magnetoplasma modeled by Lorentzian (kappa) distributions  

International Nuclear Information System (INIS)

Linear dispersion relations for electrostatic waves in spatially inhomogeneous, current-carrying anisotropic plasma, where the equilibrium particle velocity distributions are modeled by various Lorentzian (kappa) distributions and by well-known bi-Maxwellian distribution, are presented. Spatial inhomogeneities, assumed to be weak, include density gradients, temperature gradients, and gradients (shear) in the parallel (to the ambient magnetic field) flow velocities associated with the current. In order to illustrate the distinguishing features of the kappa distributions, stability properties of the low frequency (lower than ion cyclotron frequency) and long perpendicular wavelength (longer than ion gyroradius) modes are studied in detail, and the results are contrasted with those for the bi-Maxwellian distribution. Specific attention is given to the drift waves, the current-driven ion-acoustic waves in the presence of velocity shear, the velocity shear-driven ion-acoustic modes, and the ion temperature-gradient driven modes. Growth rates of the drift wave instability and the current-driven ion-acoustic instability are reduced from their values for bi-Maxwellian distribution due to larger ion Landau damping rates associated with the kappa distributions. For the same reason, excitation conditions for these two instabilities are more stringent in the case of the kappa distributions. Growth rates of the velocity shear-driven ion-acoustic instability and the ion temperatureoustic instability and the ion temperature-gradient driven instability are reduced from their values for bi-Maxwellian distribution as a consequence of the reduced adiabatic response of the electrons to the electrostatic potential perturbation. Frequencies of the drift waves and the ion-acoustic waves are also reduced in kappa-distribution plasmas due to the reduced adiabatic response of the electrons

219

Low frequency electrostatic waves in weakly inhomogeneous magnetoplasma modeled by Lorentzian (kappa) distributions  

Science.gov (United States)

Linear dispersion relations for electrostatic waves in spatially inhomogeneous, current-carrying anisotropic plasma, where the equilibrium particle velocity distributions are modeled by various Lorentzian (kappa) distributions and by well-known bi-Maxwellian distribution, are presented. Spatial inhomogeneities, assumed to be weak, include density gradients, temperature gradients, and gradients (shear) in the parallel (to the ambient magnetic field) flow velocities associated with the current. In order to illustrate the distinguishing features of the kappa distributions, stability properties of the low frequency (lower than ion cyclotron frequency) and long perpendicular wavelength (longer than ion gyroradius) modes are studied in detail, and the results are contrasted with those for the bi-Maxwellian distribution. Specific attention is given to the drift waves, the current-driven ion-acoustic waves in the presence of velocity shear, the velocity shear-driven ion-acoustic modes, and the ion temperature-gradient driven modes. Growth rates of the drift wave instability and the current-driven ion-acoustic instability are reduced from their values for bi-Maxwellian distribution due to larger ion Landau damping rates associated with the kappa distributions. For the same reason, excitation conditions for these two instabilities are more stringent in the case of the kappa distributions. Growth rates of the velocity shear-driven ion-acoustic instability and the ion temperature-gradient driven instability are reduced from their values for bi-Maxwellian distribution as a consequence of the reduced adiabatic response of the electrons to the electrostatic potential perturbation. Frequencies of the drift waves and the ion-acoustic waves are also reduced in kappa-distribution plasmas due to the reduced adiabatic response of the electrons.

Basu, B.

2008-04-01

220

Voltage impulse induced bistable magnetization switching in multiferroic heterostructures  

Science.gov (United States)

We report on voltage impulse induced reversible bistable magnetization switching in FeGaB/lead zirconate titanate (PZT) multiferroic heterostructures at room temperature. This was realized through strain-mediated magnetoelectric coupling between ferroelectric PZT and ferromagnetic FeGaB layer. Two reversible and stable voltage-impulse induced mechanical strain states were obtained in the PZT by applying an electric field impulse with its amplitude smaller than the electric coercive field, which led to reversible voltage impulse induced bistable magnetization switching. These voltage impulse induced bistable magnetization switching in multiferroic heterostructures provides a promising approach to power efficient bistable magnetization switching that is crucial for information storage.

Nan, T. X.; Zhou, Z. Y.; Lou, J.; Liu, M.; Yang, X.; Gao, Y.; Rand, S.; Sun, N. X.

2012-03-01

 
 
 
 
221

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

222

Influence of current impulse on machining characteristics in EDM  

International Nuclear Information System (INIS)

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

223

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

Science.gov (United States)

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

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

2014-04-01

224

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

Science.gov (United States)

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

Grant, Jon E; Chamberlain, Samuel R

2014-11-01

225

Pinning impulsive control algorithms for complex network  

International Nuclear Information System (INIS)

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

226

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

Science.gov (United States)

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

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

2013-01-01

227

Vacuum fluctuations for spherical gravitational impulsive waves  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Hortac?su, M.

1998-01-01

228

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

229

A Largely Reconfigurable Impulse Radio UWB Transceiver  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This letter presents a new and efficient digital baseband architecture for impulse radio ultra wideband (IR-UWB) transceivers with reconfigurable capacities for wireless sensor network (WSN) applications. An implementation is done on FPGA for validation by measurements. It achieves the highest data rate and the largest number of operating modes for an IR-UWB reconfigurable transceiver, to the best of the author's knowledge. Measurements demonstrate reconfigurability in data rate (from 4 to 12...

Lecointre, Aubin; Dragomirescu, Daniela; Plana, Robert

2010-01-01

230

Transient Impulsive Giant Electronic Raman Redistribution  

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Resonant Raman excitation by ultrafast vacuum ultraviolet laser pulses is a powerful means to study electron dynamics in molecules, but experiments must contend with linear background ionization: frequencies high enough to reach resonant core-valence transitions will usually ionize all occupied orbitals as well, and the ionization cross sections are usually dominant. Here we show that attosecond pulses can induce a new process, transient impulsive stimulated Raman scattering...

Miyabe, S.; Bucksbaum, P.

2014-01-01

231

Bending Wavelet for Flexural Impulse Response  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

232

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

233

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

234

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.)

235

Literature Survey on Impulse Noise Reduction  

Directory of Open Access Journals (Sweden)

Full Text Available In every image processing algorithm quality of image plays a very vital role because the output of thealgorithm depends on the quality of input image. Hence, several techniques are used for image qualityenhancement and image restoration. Some of them are common techniques applied to all the imageswithout having prior knowledge of noise and are called image enhancement algorithms. Some of the imageprocessing algorithms use the prior knowledge of the type of noise present in the image and are referred toas image restoration techniques. Image restoration techniques are also referred to as image de-noisingtechniques. In such cases, identified inverse degradation functions are used to restore images. In thissurvey, we review several impulse noise removal techniques reported in the literature and identify efficientimplementations. We analyse and compare the performance of different reported impulse noise reductiontechniques with Restored Mean Absolute Error (RMAE under different noise conditions. Also, we identifythe most efficient impulse noise removing filters. Marking the maximum and minimum performance offilters helps in designing and comparing the new filters which give better results than the existing filters

Manohar Koli

2013-10-01

236

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

Science.gov (United States)

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

Leeman, Robert F; Potenza, Marc N

2011-04-01

237

The integrated design of powder aligning and impulse magnetizing systems  

International Nuclear Information System (INIS)

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

238

The integrated design of powder aligning and impulse magnetizing systems  

Energy Technology Data Exchange (ETDEWEB)

This paper describes an integrated finite element based methodology for the design and analysis of powder aligning systems and impulse magnetizing fixtures for the manufacture of anisotropic bonded Nd Fe B permanent magnet components. The relationships between the final component properties and the magnitudes of the aligning field and subsequent magnetizing field are illustrated by extensive experimental characterization of a commercial grade of anisotropic Nd Fe B injection moulding compound (Compodic NDA502E). The modelling techniques employed are experimentally validated by a case study on a 4 pole self-shielding rotor, the mould and fixture parameters for which were specifically selected to produce only partial alignment and saturation. The utility of an automated design technique is illustrated by the optimization of a mould to achieve near full alignment and saturation of the 4 pole rotor. (author) 11 refs., 18 figs.

Riley, C.D.; Jewell, G.W.; Howe, D. [Sheffield Univ. (United Kingdom). Dept. of Electronic and Electrical Engineering

1996-12-31

239

Stochastic properties of gustatory impulse discharges in rat chorda tympani fibers.  

Science.gov (United States)

1. The present study was intended to elucidate the role of temporal patterns of impulse discharges of the gustatory primary afferents in the coding of taste qualities by the use of simultaneous analyses of the across-neuron patterning (5) and the temporal patterning of impulses. 2. Impulse discharges of 43 rat chorda tympani fibers elicited by gustatory stimulation (0.1 M NaCl, 0.5 M sucrose, 0.01 N HCl, 0.02 M quinine hydrochloride, 0.3 M KCl, and 0.02 M saccharin sodium) were recorded. The temporal patterns of impulse discharges elicited by these stimuli were statistically analyzed both in an initial dynamic phase and a succeeding stationary phase of responses. In the dynamic phase, the time courses of firing frequency were studied; however, these were not clearly associated with the qualities of taste stimuli. In the stationary phase, the stochastic properties of impulse trains were studied regarding the impulse trains as a stochastic point process (30). In this study, interspike interval histograms (ISI histograms), joint interval histograms, serial correlograms, and autocorrelograms were computed. 3. In general, the distribution patterns of ISI histogram were not absolutely specific to the taste qualities. However, the gamma or the exponential distribution occurred most often with 0.1 M NaCl, and the bimodal or the skewed distribution was dominated with 0.5 M sucrose stimulation among the stimuli tested. The rhythmic discharges did not occur exclusively with the sweet taste stimulation, though they occurred more often with the sweet taste stimulation than with other taste stimulations. The joint interval histogram and the serial correlogram were used to examine the stochastic properties of impulse trains with particular reference to the time dependence in the impulse trains. Generally, the time dependence was not concerned with the taste qualities. 4. The chorda tympani fibers were classified into three types according to the magnitude of responses and the temporal patterns of impulse discharges. The neurons predominantly responsive to NaCl and unresponsive to sucrose were classified as type I neurons. The remaining neurons, which moderately responded to both NaCl and sucrose, were further categorized into type II neurons and type III neurons, depending on their temporal patterns of impulse discharge. The type II neurons tended to show the rhythmic or burstlike firing of impulses in response to more than one kind of taste stimuli. 5. The results showed that the taste quality was represented in the characteristic temporal patterning of impulses as well as in the across-neuron patterning of responses. The possible origin of the temporal discharge pattern and its significance in gustatory information processing were discussed on the basis of the neuron types described above. PMID:7218015

Nagai, T; Ueda, K

1981-03-01

240

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 th...

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

2013-01-01

 
 
 
 
241

Impulsive and reflective processes related to alcohol use in young adolescents  

Directory of Open Access Journals (Sweden)

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

SaraPieters

2014-05-01

242

Stability Analysis and Design of Impulsive Control Lorenz Systems Family  

International Nuclear Information System (INIS)

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

243

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

244

Motor impulsivity during childhood and adolescence: a longitudinal biometric analysis of the go/no-go task in 9- to 18-year-old twins.  

Science.gov (United States)

In the present study, we investigated genetic and environmental effects on motor impulsivity from childhood to late adolescence using a longitudinal sample of twins from ages 9 to 18 years. Motor impulsivity was assessed using errors of commission (no-go errors) in a visual go/no-go task at 4 time points: ages 9-10, 11-13, 14-15, and 16-18 years. Significant genetic and nonshared environmental effects on motor impulsivity were found at each of the 4 waves of assessment with genetic factors explaining 22%-41% of the variance within each of the 4 waves. Phenotypically, children's average performance improved across age (i.e., fewer no-go errors during later assessments). Multivariate biometric analyses revealed that common genetic factors influenced 12%-40% of the variance in motor impulsivity across development, whereas nonshared environmental factors common to all time points contributed to 2%-52% of the variance. Nonshared environmental influences specific to each time point also significantly influenced motor impulsivity. Overall, results demonstrated that although genetic factors were critical to motor impulsivity across development, both common and specific nonshared environmental factors played a strong role in the development of motor impulsivity across age. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:25347305

Bezdjian, Serena; Tuvblad, Catherine; Wang, Pan; Raine, Adrian; Baker, Laura A

2014-11-01

245

Linking impulsivity to dysfunctional thought control and insomnia: a structural equation model.  

Science.gov (United States)

According to cognitive models of insomnia, excessive mental activity at bedtime may be viewed as an important impediment to the process of falling asleep. A further assumption of these models is that 'cognitive arousal' may be perpetuated and exacerbated by counterproductive strategies of thought management. As yet, little is known about factors that may predispose people to rely on these strategies when confronted with thoughts that keep them awake at night. This study examined the relations between impulsivity, use of different thought-control strategies and insomnia severity. A sample of 391 university students completed the UPPS Impulsive Behavior Scale, the Thought Control Questionnaire Insomnia-Revised and the Insomnia Severity Index. Correlation analyses revealed that two facets of impulsivity (urgency and lack of perseverance), two strategies of thought control (aggressive suppression and worry) and insomnia severity were positively associated. Follow-up structural equation modeling analyses showed that the two mentioned thought-control strategies mediated the effects of the two facets of impulsivity on sleep problems. These findings extend existing cognitive accounts of insomnia by suggesting how predisposing and perpetuating factors may be related: specific personality traits may incline individuals to respond with dysfunctional thought-control strategies to unwanted mental activity at night. PMID:19659917

Schmidt, Ralph E; Gay, Philippe; Ghisletta, Paolo; VAN DER Linden, Martial

2010-03-01

246

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...

Madden, Gregory J.; Johnson, P.; Brewer, A.; Pinkston, J. W.; Fowler, S.

2010-01-01

247

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...

Ajdler, Thibaut; Sbaiz, Luciano; Vetterli, Martin

2007-01-01

248

Stochastic Impulse Control of Non-Markovian Processes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Djehiche, Boualem; Hamadene, Said; Hdhiri, Ibtissam

2008-01-01

249

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...

Mirela Mihi?; Ivana Kursan

2010-01-01

250

Deletion of alpha-synuclein decreases impulsivity in mice  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The presynaptic protein alpha-synuclein, associated with Parkinson's Disease (PD), plays a role in dopaminergic neurotransmission and is implicated in impulse control disorders (ICDs) such as drug addiction. In this study we investigated a potential causal relationship between alpha-synuclein and impulsivity, by evaluating differences in motor impulsivity in the 5-choice serial reaction time task (5-CSRTT) in strains of mice that differ in the expression of the alpha-synuclein gene. C57BL/6JO...

Pen?a-oliver, Y.; Buchman, V. L.; Dalley, J. W.; Robbins, T. W.; Schumann, G.; Ripley, T. L.; King, S. L.; Stephens, D. N.

2011-01-01

251

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

252

Attention deficit and impulsivity: Driving, drugs and electrophysiology  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Impulsivity can be interpreted as a cognitive dysfunction or as a motivational dysfunction. Motivational dysfunctions are reflected in impulsive decision making such as increased preference for immediate reward over delayed more beneficial reward (delay aversion) or increased risk taking due to poor reflection on negative outcomes. Smoking is an example of impulsive decision making as it displays the tendency to choose for the immediate reward of cigarettes over reduced concern for long-term ...

Wester, A. E.

2009-01-01

253

Impulsive Deboost for Maximum and Minimum Atmospheric Entry Angles  

Directory of Open Access Journals (Sweden)

Full Text Available Deboost of rocket vehicles initially moving in elliptic orbits for maximum and minimum atmospheric entry is analysed. It is shown that in general with specified retrofire velocity impulse and entry altitude, maximum entry angle is obtained when impulse is applied tangentially at the apogee whereas entry angle occurs when retrofire impulse is applied tangentially at the perigee. Existence conditions for only maximum or minimum or both neither maximum nor minimum entry have also been investigated.

T. N. Srivastava

2014-03-01

254

Stability of impulsive neural networks with time delays  

International Nuclear Information System (INIS)

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

255

Impulsive generalized function synchronization of complex dynamical networks  

International Nuclear Information System (INIS)

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

256

Assessment of impulsivity after moderate to severe traumatic brain injury  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of the study was to develop and validate a short questionnaire assessing four dimensions of impulsivity (urgency, lack of premeditation, lack of perseverance, sensation seeking) in patients with traumatic brain injury (TBI). To this end, 82 patients with TBI and their caregivers completed a short questionnaire adapted from the UPPS Impulsive Behavior Scale designed to assess impulsivity changes after TBI. Confirmatory factor analyses (CFAs) performed on the version of the scale comple...

Rochat, Lucien; Beni, Catia; Billieux, Joe?l; Azouvi, Philippe; Annoni, Gian-maria; Linden, Martial

2010-01-01

257

FPGA IMPLEMENTATION OF RSEPD TECHNIQUE BASED IMPULSE NOISE REMOVAL  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the process of signals transmission and acquisition, image signals might be corrupted by impulse noise. Generally, digital images are corrupted by impulse noises. These are short duration noises, which degrade an image and are randomly distributed over the image. An efficient FPGA implementation for removing impulse noise in an image is presented in this paper. Existing techniques use standard median filter. These existing approaches changes the pixel values of both noise less and noisy pi...

Rajadurai, M.; Santhi, M.

2013-01-01

258

The definition of electro impulses used in weed control  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Judaev I.V.

2008-01-01

259

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

260

Impulsive synchronization of Chen's hyperchaotic system  

Energy Technology Data Exchange (ETDEWEB)

In this Letter the impulsive synchronization of the Chen's hyperchaotic systems is discussed. Some new and sufficient conditions on varying impulsive distance are established in order to guarantee the synchronizabillity of the systems using the synchronization method. In particular, some simple conditions are derived in synchronizing the systems by equal impulsive distances. Two illustrative examples are provided to show the feasibility and the effectiveness of the proposed method. The boundaries of the stable regions are also estimated.

Haeri, Mohammad [Advanced Control System Lab, Electrical Engineering Department, Sharif University of Technology, Tehran (Iran, Islamic Republic of)]. E-mail: haeri@sina.sharif.edu; Dehghani, Mahsa [Advanced Control System Lab, Electrical Engineering Department, Sharif University of Technology, Tehran (Iran, Islamic Republic of)

2006-08-07

 
 
 
 
261

Effects of emotional context on impulse control.  

Science.gov (United States)

High risk behaviors such as narcotic use or physical fighting can be caused by impulsive decision making in emotionally-charged situations. Improved neuroscientific understanding of how emotional context interacts with the control of impulsive behaviors may lead to advances in public policy and/or treatment approaches for high risk groups, including some high-risk adolescents or adults with poor impulse control. Inferior frontal gyrus (IFG) is an important contributor to response inhibition (behavioral impulse control). IFG also has a role in processing emotional stimuli and regulating emotional responses. The mechanism(s) whereby response inhibition processes interact with emotion processing in IFG are poorly understood. We used 4.7 T fMRI in 20 healthy young adults performing a rapid event-related emotional Go/NoGo task. This task combined the Go/NoGo task, which is a classic means of recruiting response inhibition processes, with emotionally neutral and aversive distractor images. In IFG, both response inhibition in an emotionally neutral context (neutral NoGo trials) and aversive emotional picture processing (aversive Go trials) evoked activation greater than the simple response baseline (neutral Go trials). These results are consistent with the literature. Activation for response inhibition in aversive contexts (aversive NoGo-neutral Go trials) was approximately the sum of response inhibition activation (neutral NoGo-neutral Go) and aversive emotional distractor activation (aversive Go-neutral Go). We conclude that response inhibition and aversive emotional stimulus processing activities combine additively (linearly) in IFG, rather than interfering with each other (sub-linearly) or mutually-enhancing each other (super-linearly). We also found previously undocumented interaction effects between response inhibition (NoGo vs. Go) and emotional context (aversive vs. neutral distractor pictures) in bilateral posterior middle temporal gyrus and angular gyrus, right frontal eye field, and other brain regions. These results may reflect the interaction of attention processes driven by emotional stimuli with conflict resolution processes related to Go/NoGo performance. PMID:22781161

Brown, Matthew R G; Lebel, R Marc; Dolcos, Florin; Wilman, Alan H; Silverstone, Peter H; Pazderka, Hannah; Fujiwara, Esther; Wild, T Cameron; Carroll, Alan M; Hodlevskyy, Oleksandr; Zedkova, Lenka; Zwaigenbaum, Lonnie; Thompson, Angus H; Greenshaw, Andrew J; Dursun, Serdar M

2012-10-15

262

Impulse Noise removal in Digital Images  

Directory of Open Access Journals (Sweden)

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

M.JayaManmadhaRao,

2010-10-01

263

Transient Impulsive Giant Electronic Raman Redistribution  

CERN Document Server

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

Miyabe, S

2014-01-01

264

High power impulse magnetron sputtering discharge  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2012-01-01

265

Impulse Plasma Deposition (IPD) of Compound powder  

International Nuclear Information System (INIS)

Different powder materials have been deposited by Impulse plasma Deposition(IPD) using coaxial plasma accelerator. Commercial compound powder is placed at the breach of the plasma accelerator. For discharge energy of 208 Joule, the deposited layer thickness was 3 nm/pulse. Analyses showed that the deposited layer consists of the different materials in the powder compound. Plasma current sheath carried the powder ions has been studied experimentally and theoretically. The grain size distribution for the deposited materials showed that most of the grain size is 2 um with Maxwellian distribution

266

Dissecting impulsivity and its relationships to drug addictions.  

Science.gov (United States)

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

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

2014-10-01

267

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

268

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

269

Influence of demographic and individual difference factors on impulse buying  

Directory of Open Access Journals (Sweden)

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

Mirela Mihi?

2010-06-01

270

PERFORMANCE OF IMPULSE NOISE DETECTION METHODS IN REMOTE SENSING IMAGES  

Directory of Open Access Journals (Sweden)

Full Text Available Remote sensing (RS images are affected by different types of noises like Gaussian noise, speckle noise and impulse noise. These noises are introduced into the RS images during acquisition or transmission process. The main challenge in impulse noise removal is to suppress the noise as well as to preserve the details (edges. Removal ofthe impulse noise is done by two stages: detection of noisy pixel and replacement of that pixel. Detecting and Removing or reducing impulse noise is a very active research area in image processing. In this paper three different existing detection methods are discussed with the intension of developing a new one.

Mrs.V.RADHIKA,

2010-09-01

271

Solar Impulse - Around the World in a Solar Airplane  

Digital Repository Infrastructure Vision for European Research (DRIVER)

- Einführung in das Projekt Solar Impulse (Entstehung, Herausforderung, Errungenschaften) - Beschreibung der eingesetzten Software Tools zur Entwicklung des Flugzeuges - Fallbeispiele für den Einsatz von Mathcad

Leblois, Richard

2012-01-01

272

Impulses for the new German energy concept; Impulse fuer das neue deutsche Energiekonzept  

Energy Technology Data Exchange (ETDEWEB)

The energy forum 2007 at 15th March, 2007, in Berlin (Federal Republic of Germany), dealt with impulses for the new German energy concept. The central message was the request of the policy for stable, reliable, transparent and simple boundary conditions. The topics of the discussions were energy mix, climate protection, supply security, economy and energy research.

NONE

2007-07-01

273

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...

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

2011-01-01

274

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...

Sturm, Bob L.; Defrance, Guillaume

2010-01-01

275

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 ...

Berthe, Abdoulaye; Lecointre, Aubin; Dragomirescu, Daniela; Plana, Robert

2009-01-01

276

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

277

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

International Nuclear Information System (INIS)

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

278

Impulsive brightenings in quiescent solar prominences  

International Nuclear Information System (INIS)

At large spatial scales, quiescent solar prominences appear static in nature, but they are dynamic at smaller scales. This thesis reports on high resolution observations of quiescent prominences using the tunable, Universal Birefringent Filter and the echelle spectrograph on the Vacuum Tower Telescope at Sacramento Peak Observatory. More than 40 hours of wavelength scans of H alpha and HeD3 disclose a class of activity near the edges of quiescent prominences, characterized by enhancement of H alpha radiative power by as much as 4 x 1024 erg s-1 and enhanced line widths of up to 0.92 A, over areas 5 to 25 arcseconds across, for lifetimes of tens of minutes; we call this activity impulsive brightenings. The H alpha profile is centrally reversed by as much as 25% in some, while other contain significant line-of-sight velocities. Brightenings with H alpha reversal show correlations between depth of reversal and both line width and peak intensity. The correlation between line width and reversal depth is closest; as functions of time and position these quantities display similar behavior. Comparison of the reversed profiles with those from a surge suggest an opacity-related cause of the central reversals. The other activity displays doppler shifts corresponding to 2 to 50 km s-1 and the H alpha profiles indicate high opacities, but are not necessarily reversed. Three models for impulsive brightening are consideredrightening are considered

279

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)

280

Relationship between circadian typology and functional and dysfunctional impulsivity.  

Science.gov (United States)

The present study explores the relationships between functional and dysfunctional impulsivity factors, circadian typology, and sex. A sample of 850 university students (396 men) aged between 18 and 33 yrs of age completed the Dickman's Impulsivity Inventory (DII) and reduced morningness-eveningness questionnaire (rMEQ). Factorial analysis showed a dimensional clustering with satisfactory item saturation for both dimensions of impulsivity, especially in men and evening-type. Men presented higher values than women for functional and dysfunctional impulsivity, while morning-type subjects obtained lower scores in dysfunctional impulsivity than the neither- and evening-types. An interactive effect between circadian typology and sex was obtained for dysfunctional impulsivity. Higher scores in men for dysfunctional impulsivity were found in neither- and evening-types, while no significant differences were obtained between men and women in the morning-type group. The morning-type typology can be considered a protective factor for impulse control disorders, especially in men, but further research is needed on the clinical and neurobiological implications of our results. PMID:20524804

Adan, Ana; Natale, Vincenzo; Caci, Hervé; Prat, Gemma

2010-05-01

 
 
 
 
281

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

282

A new Calculation Procedure for Spatial Impulse Responses in Ultrasound  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 surf...

Jensen, Jørgen Arendt

2006-01-01

283

Existence of periodic solutions of impulsive differential systems  

Directory of Open Access Journals (Sweden)

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

L. H. Erbe

1991-01-01

284

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)

285

Effects of Strategies Marketing of Collective Buying about Impulsive Behavior  

Directory of Open Access Journals (Sweden)

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

Suzi Elen Ferreira Dias

2014-08-01

286

Individual Differences in Impulsive Choice and Timing in Rats  

Science.gov (United States)

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

Galtress, Tiffany; Garcia, Ana; Kirkpatrick, Kimberly

2012-01-01

287

Chaotic attitude control of satellite using impulsive control  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-10-30

288

Chaotic attitude control of satellite using impulsive control  

International Nuclear Information System (INIS)

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

289

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

Science.gov (United States)

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. PMID:23938342

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

2013-01-01

290

Partial discharge characteristics and mechanism in voids at impulse voltages  

International Nuclear Information System (INIS)

Partial discharge (PD) characteristics and mechanism in artificial cavities in an epoxy plate have been investigated for different void dimensions and impulse voltage waveforms. A differential measurement system was developed in order to detect PD current pulses effectively. Experimental results showed that the 50% probability PD inception voltage (PDIV50) increases initially as the cavity diameter decreases at constant depth for double exponential impulses as well as oscillating impulses, but after aging, it becomes independent of the cavity diameter. Moreover, some distinctive characteristics of PD (e.g. main discharge and reverse discharge during the rise and fall phases of the applied voltage) were also investigated. The differences of the PD propagation and the mechanism between double exponential impulses and oscillating impulse were discussed

291

[Effect of narcotic analgesics on the cortical control process of impulse transmission in the afferent pathways of the sciatic nerve].  

Science.gov (United States)

The effect produced by narcotic analgetics with their intravenous administration on the process of cortical control over the transmission of impulses along specific routes of the sciatic nerve was studied. The conditioning stimulation of the cortex was effected by using a monopolar electrode through single electric impulses. The interval between conditioning and test (on sciatic nerve) impulses was of 80-120 ms. Morphine (1-2 mg/kg), promedol (trimeperidin) (1-2 mg/kg) and phentanyl (100 gamma/kg) potentiated the inhibition of evoked potentials in the nucleus gracilis and in VPL, observed upon stimulation of the cortex of optic lobuses. The intensification of inhibitory corticifugal mechanisms occurring under the effect of narcotic analgetics takes place both on the level of the medulla oblongata and of the thalamic one. PMID:6310

Churiukanov, V V; Bilibin, D P

1976-01-01

292

When is "impulsiveness" not impulsive? The case of hyperactive children's cognitive style.  

Science.gov (United States)

On two computerized versions of the Matching Familiar Figures Test (MFFT; Kagan, Child Development, 36, 609-628, 1965) pervasively hyperactive and matched control children had to identify a target from among five similar foils. One version had a temporal structure similar to the manual MFFT and trial length was determined by response speed. Hyperactive children behaved in an "impulsive" manner; they responded more quickly and made more mistakes than controls. Despite this they completed each trial more quickly than controls by identifying the target. On the second version, the length of each trial was fixed at 45 seconds. Although both groups were equally "reflective", hyperactive children still made more mistakes. Implications of these results for research in impulse control in general and hyperactivity in particular are discussed. PMID:7806608

Sonuga-Barke, E J; Houlberg, K; Hall, M

1994-10-01

293

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

294

Work done by a Gaussian impulse  

Science.gov (United States)

This paper was first motivated by the following question: 'A pair of twins, R and S, each gives the same hard push on a block. R's block is on a rougher floor than S's. Who does more work?' It is shown that S will do more work on his block if there is no constraint on the distance over which the force is applied. On the other hand, if the assumption is relaxed to 'the same hard push within some distance', say due to the length of their arms, then it is possible that R does more work than S. To resolve this issue, general formulae for the velocity, displacement and work done are obtained for a Gaussian impulsive force acting on a body moving on a horizontal surface.

Foong, S. K.

2010-05-01

295

Compton scattering beyond the impulse approximation  

CERN Document Server

We treat the non-relativistic Compton scattering process in which an incoming photon scatters from an N-electron many-body state to yield an outgoing photon and a recoil electron, without invoking the commonly used frameworks of either the impulse approximation (IA) or the independent particle model (IPM). An expression for the associated triple differential scattering cross section is obtained in terms of Dyson orbitals, which give the overlap amplitudes between the N-electron initial state and the (N-1) electron singly ionized quantum states of the target. We show how in the high energy transfer regime, one can recover from our general formalism the standard IA based formula for the cross section which involves the ground state electron momentum density (EMD) of the initial state. Our formalism will permit the analysis and interpretation of electronic transitions in correlated electron systems via inelastic x-ray scattering (IXS) spectroscopy beyond the constraints of the IA and the IPM.

Kaplan, I G; Bansil, A

2003-01-01

296

Impulse oscillometry: interpretation and practical applications.  

Science.gov (United States)

Simple spirometry and body plethysmography have been routinely used in children aged > 5 years. New techniques based on physiologic concepts that were first described almost 50 years ago are emerging in research and in clinical practice for measuring pulmonary function in children. These techniques have led to an increased understanding of the pediatric lung and respiratory mechanics. Impulse oscillometry (IOS), a simple, noninvasive method using the forced oscillation technique, requires minimal patient cooperation and is suitable for use in both children and adults. This method can be used to assess obstruction in the large and small peripheral airways and has been used to measure bronchodilator response and bronchoprovocation testing. New data suggest that IOS may be useful in predicting loss of asthma control in the pediatric population. This article reviews the clinical applications of IOS, with an emphasis on the pediatric setting, and discusses appropriate coding practices for the clinician. PMID:25180727

Bickel, Scott; Popler, Jonathan; Lesnick, Burton; Eid, Nemr

2014-09-01

297

Photonic generation multiband UWB impulse radio signal  

Science.gov (United States)

A novel method to photonic generation multiband ultra-wide band (MB-UWB) impulse radio signal based on the summation of multiple doublet pulses with different weights and proper time delays is proposed. Microwave sinusoidal signal is used to amplitude modulate a tunable laser to get multi-wavelength source. The optical signal is then phase modulation with Gaussian pulse and fed into a section of single-mode fiber (SMF). The SMF services as phase modulation to intensity modulation (PM-IM) conversion to generate Gaussian doublet pulse, and offers proper time delays to Gaussian doublet pulses with different weights. MB-UWB pulses with sidelobe suppression levels over 25 dB, central frequency from 5 to 8 GHz, 10 dB bandwidth from 2.9 to 3.8 GHz are obtained in experiment.

Sun, Guodan; Wang, Rong; Pu, Tao; Wei, Zhihu

2013-05-01

298

Stabilizing effects of impulses in discrete-time delayed neural networks.  

Science.gov (United States)

This brief studies the global exponential stability of the equilibrium point of discrete-time delayed Hopfield neural networks (DHNNs) with impulse effects by using difference inequalities. We shall consider the stabilizing effects of impulses when the corresponding impulse-free DHNN is even not asymptotically stable. The obtained results characterize the aggregated effects of impulses and deviation of the impulse-free DHNN from its equilibrium point on the exponential stability of the whole system. It is shown that, because of effects of impulses, the impulsive discrete-time DHNN may be exponentially stable even if the evolution of impulse-free component deviates from its equilibrium point exponentially. PMID:21233048

Li, Chuandong; Wu, Sichao; Feng, Gang Gary; Liao, Xiaofeng

2011-02-01

299

Impulsive moving mirror model and impulsive differential equations in Banach space  

International Nuclear Information System (INIS)

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

300

Relations between trait impulsivity, behavioral impulsivity, physiological arousal, and risky sexual behavior among young men.  

Science.gov (United States)

The current study examined how impulsivity-related traits (negative urgency, sensation seeking, and positive urgency), behavioral measures of risk taking and reward seeking, and physiological reactivity related to three different risky sexual behaviors in sexually active undergraduate men (N = 135). Regression analyses indicated that sensation seeking and behavioral risk-taking predicted unique variance in number of sexual partners. These findings suggest that, for young men, acquisition of new partners is associated with need for excitement and reward and willingness to take risks to meet those needs. Sensation seeking, behavioral risk-taking, and skin conductance reactivity to arousing stimuli was related to ever having engaged in sex with a stranger, indicating that, for men, willingness to have sex with a stranger is related not only to the need for excitement and risk-taking but also with innate responsiveness to arousing environmental triggers. In contrast, regression analyses indicated that young men who were impulsive in the context of negative emotions were less likely to use condoms, suggesting that emotion-based impulsivity may be an important factor in negligent prophylactic use. This study adds to the current understanding of the divergence between the correlates of risky sexual behaviors and may lend utility to the development of individualized HIV prevention programming. PMID:24958252

Derefinko, Karen J; Peters, Jessica R; Eisenlohr-Moul, Tory A; Walsh, Erin C; Adams, Zachary W; Lynam, Donald R

2014-08-01

 
 
 
 
301

Prediction of energy decay in room impulse responses simulated with an image-source model.  

Science.gov (United States)

A method is proposed that provides an approximation of the acoustic energy decay (energy-time curve) in room impulse responses generated using the image-source technique. A geometrical analysis of the image-source principle leads to a closed-form expression describing the energy decay curve, with the resulting formula being valid for a uniform as well as nonuniform definition of the enclosure's six absorption coefficients. The accuracy of the proposed approximation is demonstrated on the basis of impulse-response simulations involving various room sizes and reverberation levels, with uniform and nonuniform sound absorption coefficients. An application example for the proposed method is illustrated by considering the task of predicting an enclosure's reflection coefficients in order to achieve a specific reverberation level. The technique presented in this work enables designers to undertake a preliminary analysis of a simulated reverberant environment without the need for time-consuming image-method simulations. PMID:18646975

Lehmann, Eric A; Johansson, Anders M

2008-07-01

302

Impulsivity and control of inhibition in Benign Focal Childhood Epilepsy (BFCE).  

Science.gov (United States)

Childhood epilepsy represents abnormal brain functioning and may affect cognitive functions that depend on the late development of the frontal lobes. This study addresses the possible consequences of benign epilepsy on frontal functions, specifically action regulation and inhibition in the absence of explicit frontal neurological signs. Thirteen children (8 males; 6-12 years old) with benign epilepsy were matched to 13 controls. They performed tasks designed to measure impulsivity and control of inhibition: CPT, Stop Signal Paradigm, Stroop test, and Matching Familiar Figures Test (MFFT). Children with epilepsy made more errors on the MFFT (p < .02), made more errors in the interference condition on the Stroop test (p < .01), and had a longer response time to the Stop Signal (p < .05) than controls, with no differences on nonexecutive functions measures. Thus, children with benign epilepsy have a deficit on some measures of impulsivity and inhibition, which may reflect poor frontal lobe functioning. PMID:10857669

Chevalier, H; Metz-Lutz, M N; Segalowitz, S J

2000-01-01

303

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

Directory of Open Access Journals (Sweden)

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

MassimoSartori

2013-06-01

304

Additive effects of serotonergic and dopaminergic polymorphisms on trait impulsivity.  

Science.gov (United States)

Twin studies suggest 45% heritability of trait impulsivity. Results from candidate gene studies to date are contradictory; impulsivity phenotypes were measured by different behavioral and questionnaire methods related either to the dopaminergic or to the serotonergic system. Here we report an association study of both dopaminergic (COMT rs4680, DRD4 48?bp VNTR, DRD2/ANKK1 rs1800497) and serotonergic (HTR1A rs6925, HTR1B rs13212041, SLC6A4 5-HTTLPR) gene polymorphisms and trait impulsivity assessed with the Barratt Impulsiveness Scale (BIS-11) in a sample of 687 Caucasian young adults. Results showed lower impulsivity in the presence of the DRD4 7-repeat (P?=?0.006) and the HTR1B rs13212041 alleles (P?=?0.003). These findings stayed significant after Bonferroni correction. A multivariate analysis using Bayesian networks confirmed independent effects of these two polymorphisms and provided a coherent characterization of the system of dependencies with respect to the impulsivity construct as well as its subscales. These results clearly suggest an additive effect of dopaminergic and serotonergic polymorphisms on trait impulsivity. PMID:22259185

Varga, Gabor; Szekely, Anna; Antal, Peter; Sarkozy, Peter; Nemoda, Zsofia; Demetrovics, Zsolt; Sasvari-Szekely, Maria

2012-04-01

305

Simulation of impulse effects from explosive charges containing metal particles  

Science.gov (United States)

The propagation of an explosive blast wave containing inert metal particles is investigated numerically using a robust two-phase methodology with appropriate models to account for real gas behavior, inter-phase interactions, and inter-particle collisions to study the problem of interest. A new two-phase Eulerian-Lagrangian formulation is proposed that can handle the dense nature of the flow-field. The velocity and momentum profiles of the gas and particle phases are analyzed and used to elucidate the inter-phase momentum transfer, and its effect on the impulsive aspects of heterogeneous explosive charges. The particles are found to pick up significant amounts of momentum and kinetic energy from the gas, and by virtue of their inertia, are observed to sustain it for a longer time. The impulse characteristics of heterogeneous explosives are compared with a homogeneous explosive containing the same amount of high explosive, and it is observed that the addition of solid particles augments the impulsive loading significantly in the near-field, and to a smaller extent in the far-field. The total impulsive loading is found to be insensitive to the particle size added to the explosive charge above a certain cut-off radius, but the individual impulse components are found to be sensitive, and particles smaller than this cut-off size deliver about 8% higher total impulse than the larger ones. Overall, this study provides crucial insights to understand the impulsive loading characteristics of heterogeneous explosives.

Balakrishnan, K.; Nance, D. V.; Menon, S.

2010-06-01

306

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

International Nuclear Information System (INIS)

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

307

Stability of impulsive neural networks with time delays  

Energy Technology Data Exchange (ETDEWEB)

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

Zhang Yu [Department of Applied Mathematics, Tongji University, Shanghai 200092 (China); Sun Jitao [Department of Applied Mathematics, Tongji University, Shanghai 200092 (China)]. E-mail: sunjt@sh163.net

2005-12-19

308

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

309

Impulsive Alfven coupling between the magnetosphere and ionosphere  

International Nuclear Information System (INIS)

Basic properties of the impulsive Alfven interaction between the magnetosphere and ionosphere have been studied by means of a three-dimensional self-consistent simulation of the coupled magnetosphere and ionosphere system. It is found that the duration time of an impulsive perturbation at the magnetospheric equator, the latitudinal distribution of the Alfven propagation time along the field lines, and the ratio between the magnetospheric impedance and the ionospheric resistance is the main key factors that determine the propagation dynamics and the ionospheric responses for an impulsive MHD perturbation in the magnetosphere. (author)

310

The definition of electro impulses used in weed control  

Directory of Open Access Journals (Sweden)

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

Judaev I.V.

2008-01-01

311

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Revisar os artigos sobre substratos neurobiológicos dos transtornos do controle dos impulsos. O jogo patológico é o foco central desta revisão na medida em que a maioria dos estudos biológicos dos formalmente classificados como transtornos do controle dos impulsos examinou este transtorno. [...] MÉTODO: Foi feita uma busca no banco de dados Medline de artigos publicados de 1966 até o presente para identificar aqueles relevantes para serem revisados neste artigo. DESFECHOS: Estudos pré-clínicos sugerem que a neuromodulação das monoaminas cerebrais está associada à tomada de decisões impulsivas e aos comportamentos de risco. Os estudos clínicos implicam diversos sistemas de neurotransmissores (serotoninérgico, dopaminérgico, adrenérgico e opióide) na fisiopatologia do jogo patológico e de outros transtornos do controle dos impulsos. Estudos de neuroimagem preliminares têm indicado o córtex pré-frontal ventromedial e o estriato ventral como atuantes na fisiopatologia do jogo patológico e de outros transtornos do controle dos impulsos. As contribuições genéticas para o jogo patológico parecem substanciais e os estudos iniciais têm relacionado esse transtorno a polimorfismos alélicos específicos, ainda que os achados de varredura genômica ainda tenham que ser publicados. CONCLUSÃO: Mesmo que tenham sido logrados avanços significativos em nossa compreensão sobre os transtornos do controle dos impulsos, mais pesquisas são necessárias para ampliar o conhecimento existente e traduzir esses achados em avanços clínicos. Abstract in english OBJECTIVE: To review the neurobiological substrates of impulse control disorders. Pathological gambling is a main focus of the review in that most biological studies of the formal impulse control disorders have examined this disorder. METHOD: The medical database Medline from 1966 to present was sea [...] rched to identify relevant articles that were subsequently reviewed to generate this manuscript. RESULTS: Preclinical studies suggest that differential brain monoamine neuromodulation is associated with impulsive decision-making and risk-taking behaviors. Clinical studies implicate multiple neurotransmitter systems (serotonergic, dopaminergic, adrenergic, and opioidergic) in the pathophysiology of pathological gambling and other impulse control disorders. Initial neuroimaging studies have implicated the ventromedial prefrontal cortex and ventral striatum in the pathophysiology of pathological gambling and other impulse control disorders. Genetic contributions to pathological gambling seem substantial and initial studies have implicated specific allelic polymorphisms, although genome-wide analyses have yet to be published. CONCLUSION: Although significant advances have been made in our understanding of the neurobiology of impulse control disorders, more research is needed to extend existing knowledge and translate these findings into clinical advances.

Wendol A, Williams; Marc N, Potenza.

2008-05-01

312

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

Science.gov (United States)

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

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

2014-11-01

313

Model of laser impulse coupling to metals  

International Nuclear Information System (INIS)

A two-dimensional hydrodynamics code, LITE (Laser Interaction with Targets Experiment), has been developed to calculate the plasma dynamics and impulse coupling of short wavelength lasers to metal targets in vacuum. The code has been optimized for speed and performance in the range of laser intensities from 10/sup 7/ up to about 10/sup 11/ W/cm/sup 2/ and spot sizes as small as 1 mm. The LITE code is unique in several respects. The hydrodynamics is solved by a hybrid of 1-D Lagrangian and 2-D Eulerian codes to which 1-D nonlinear thermo-physics in the solid target is coupled. The ablation rate is determined by energy balance and by a two-phase thermodynamic treatment of the solid-to-vapor interface that uses a semiempirical modification of the Clausius-Clapeyron equation. Instead of using equation-of-state lookup tables, the code calculates populations of multiple ionization states and uses the ideal gas law for electrons, ions, and neutrals. Laser absorption by inverse bremsstrahlung photoionization, and resonant absorption is found self-consistently with the degree of ionization. Latent heats, ionization, excitation, and plasma reradiation are treated as energy sinks. Thermal conduction by electrons and phonons is also included

314

Impulsive dynamic equations on a time scale  

Directory of Open Access Journals (Sweden)

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

315

Performance analysis of the impulse shift transmission  

Energy Technology Data Exchange (ETDEWEB)

The transmission plays a key role in improving the driven train's comfort, fuel efficiency and performance. Both the comfort and fuel efficiency can be greatly improved by earlier upshifting, i.e., driving with lower average engine speeds. However, by doing so a solution should be found to improve the acceleration response (agility), and damping of engine oscillations, while adhering to strict packaging and cost issues. Both items run into principal limitations due to constraints on the engine sided inertias in the drivetrain. For acceleration performance these inertias should be as small as possible. On the other hand, for improving the damping of engine oscillations these inertias should be high, as is the case with a Dual Mass Flywheel (DMF). Drivetrain Innovations BV (DTI) has lifted this compromise to a higher level by reconfiguring the engine and transmission inertias. The new 'Impulse Shift (IS)' configuration is integrated with the launch clutch into a module comparable to a DMF. Additional to a DMF, the second inertia of the IS-module partly cancels out the parasitic dynamic effects from the engine-flywheel inertia during downshifts. In combination with an Automated Manual Transmission (AMT), the IS-module also enables shifting with torque fill in all up- and downshifts. In this paper simulations of the performance of the IS-module are presented and compared to those of AMT equipped vehicles. Furthermore, comfort and fuel economy are quantified and discussed. (orig.)

Druten, R. van; Pesgens, M.; Vroemen, B.; Serrarens, A. [Drivetrain Innovations BV, Eindhoven (Netherlands)

2004-07-01

316

Generalized impulse response analysis: General or Extreme?  

Scientific Electronic Library Online (English)

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

Hyeongwoo, Kim.

2013-12-01

317

Gigabit impulse radio UWB signal generation and fiber transmission  

DEFF Research Database (Denmark)

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

Rodes Lopez, Roberto; Gibbon, Timothy Braidwood

318

Numerical analysis on acoustic impulse response for watermelon  

International Nuclear Information System (INIS)

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

319

Eyes Wide Shopped: Shopping Situations Trigger Arousal in Impulsive Buyers  

Science.gov (United States)

The present study proposes arousal as an important mechanism driving buying impulsiveness. We examined the effect of buying impulsiveness on arousal in non-shopping and shopping contexts. In an eye-tracking experiment, we measured pupil dilation while participants viewed and rated pictures of shopping scenes and non-shopping scenes. The results demonstrated that buying impulsiveness is closely associated with arousal as response to viewing pictures of shopping scenes. This pertained for hedonic shopping situations as well as for utilitarian shopping situations. Importantly, the effect did not emerge for non-shopping scenes. Furthermore, we demonstrated that arousal of impulsive buyers is independent from cognitive evaluation of scenes in the pictures. PMID:25489955

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

2014-01-01

320

Pinning impulsive synchronization of complex-variable dynamical network  

Science.gov (United States)

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

Wu, Zhaoyan; Liu, Danfeng; Ye, Qingling

2015-01-01

 
 
 
 
321

Impulsive stimulated light scattering from opaque materials at high pressure  

International Nuclear Information System (INIS)

Recent progress in the application of impulsive stimulated light scattering to opaque materials under high pressure is reviewed. Measured elastic constants and sound velocities of polycrystalline hcp ?-iron to 115 GPa are presented

322

On second order impulsive functional differential equations in Banach spaces  

Directory of Open Access Journals (Sweden)

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

323

Existence and uniqueness of solutions to impulsive fractional differential equations  

Directory of Open Access Journals (Sweden)

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

324

Numerical analysis on acoustic impulse response for watermelon  

Energy Technology Data Exchange (ETDEWEB)

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

Kim, Yong Sul; Yang, Dong Hoon; Choi, Young Jae; Bae, Tas Joo; So, Chul Ho [Dongshin University, Naju (Korea, Republic of); Lee, Yun Ho [Korea Inspection and Engineering CO.,LTD., Seoul (Korea, Republic of)

2002-11-15

325

Existence and uniqueness of solutions to impulsive fractional differential equations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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; Mouffak Benchohra

2009-01-01

326

Stability Criteria for Linear Hamiltonian Systems Under Impulsive Perturbations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Stability criteria are given for linear periodic Hamiltonian systems with impulse effect. A Lyapunov type inequality and a disconjugacy criterion are also established. The results improve the ones in the literature for such systems.

Kayar, Zeynep; Zafer, Agacik

2011-01-01

327

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

328

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

Science.gov (United States)

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

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

2015-02-01

329

ALIGNEMENT UNI ET TRIDIMENSIONNEL DE MOLÉCULES PAR IMPULSION LASER FEMTOSECONDE  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Le sujet de cette thèse concerne l'étude de l'alignement de molécules linéaires et asymétriques engendré par une impulsion laser intense. Dans le cas d'une impulsion courte par rapport à la rotation moléculaire, l'alignement créé est périodique après l'extinction du champ. Nous étudions théoriquement et expérimentalement les effets d'intensité, de température et de polarisation du champ électrique sur l'alignement produit. Pour des champs polarisés linéairement, l'interact...

Rouze?e, Arnaud

2007-01-01

330

Impulsivity: The Behavioral and Neurological Science of Discounting  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Impulsivity explores the basis for the seemingly universal tendency to devalue rewards or punishments that are not immediately available. When confronted with any number of modern impulsive behaviors such as drug use, pathological gambling, marital infidelity, and gluttony individuals have a choice with two outcomes: an immediate benefit, such as getting high, or a delayed or probabilistic benefit, such as health, money saved, or the satisfaction of a good life. This volume is an approachable...

Madden, Gregory J.; Bickel, Warren K.

2010-01-01

331

Do Different Facets of Impulsivity Predict Different Types of Aggression?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2011-01-01

332

Periodic solution for nonautonomous cellular neural networks with impulses  

International Nuclear Information System (INIS)

In this paper, we study existence, uniqueness and global stability of periodic solution (i.e., stationary oscillation) for general nonautonomous cellular neural networks with impulses. Some criteria are obtained for stationary oscillation of the nonautonomous cellular neural networks with impulses. It is derived by using a new method which is different from those of the previous literatures. Previous results are extended and improved. An illustrative example is given to demonstrate the effectiveness and less conservativeness of the obtained results.

333

Impulse control disorders in Parkinson’s disease: recent advances  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Voon, V.; Mehta, Ar; Hallett, M.

2011-01-01

334

Design of IIR Filters by Impulse Response Optimisation  

Directory of Open Access Journals (Sweden)

Full Text Available The contribution describes a program system to design digital IIR filters by optimisation of impulse response. Besides briefly presenting the already published method, it emphasizes the necessity to regularize the problem by changing the requested impulse response into a causal one by reshuffling its values. The program enables to design the filters starting from either frequency or time domain response and also from a manually prescribed pole configuration which is particularly useful for teaching purposes.

J. Jan

1996-06-01

335

Acoustic Radiation Force Impulse (ARFI) Imaging: a Review  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Nightingale, Kathy

2011-01-01

336

Switched impulsive control of the endocrine disruptor diethylstilbestrol singular model  

Science.gov (United States)

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

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

2014-12-01

337

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

338

Orthogonal Exponential Spline Pulses with Application to Impulse Radio  

Digital Repository Infrastructure Vision for European Research (DRIVER)

With application to the impulse radio communications in mind, a locally supported and zero-mean pulse which is orthogonal to its shifts by integers is sought among the exponential splines having the knot interval 1/2 . An example pulse is obtained that complies with the regulation imposed by the US Federal Communications Commission and will potentially enable an impulse radio communications system as fast as 6G pulses per second.

Kamada, Masaru; O?zlem, Semih; Habuchi, Hiromasa

2009-01-01

339

Magnetic reconnection in the heliosphere: impulsive dynamics and particle acceleration  

International Nuclear Information System (INIS)

Magnetic reconnection in the heliosphere is often time-dependent and impulsive, as in the classic instance of solar flares. A large fraction of the energy liberated during such events shows up in the energy of accelerated particles. Collisionless reconnection theory can account for significant features of these observations, but several open questions remain. Recent theoretical developments and observations that shed light on impulsive reconnection dynamics and particle acceleration mechanisms will be reviewed. (author)

340

Impulsivity and Emotional Factors in Obesity: A Preliminary Study  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 spli...

Fatma Özlem Orhan; Bilge Burçak Annagür; Ali Özer; Lut Tamam; Çi?dem Erhan

2012-01-01

 
 
 
 
341

Impulse Control of a Diffusion with a Change Point  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper solves a Bayes sequential impulse control problem for a diffusion, whose drift has an unobservable parameter with a change point. The partially-observed problem is reformulated into one with full observations, via a change of probability measure which removes the drift. The optimal impulse controls can be expressed in terms of the solutions and the current values of a Markov process adapted to the observation filtration. We shall illustrate the application of our ...

Abbas-turki, Lokman A.; Karatzas, Ioannis; Li, Qinghua

2014-01-01

342

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Voon, V.; Gao, J.; Brezing, C.; Symmonds, M.; Ekanayake, V.; Fernandez, H.; Dolan, Rj; Hallett, M.

2011-01-01

343

INDIVIDUAL DIFFERENCES IN IMPULSIVE CHOICE AND TIMING IN RATS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Individual differences in impulsive choice behavior have been linked to a variety of behavioral problems including substance abuse, smoking, gambling, and poor financial decision-making. Given the potential importance of individual differences in impulsive choice as a predictor of behavioral problems, the present study sought to measure the extent of individual differences in a normal sample of hooded Lister rats. Three experiments utilized variations of a delay discounting task to measure th...

Galtress, Tiffany; Garcia, Ana; Kirkpatrick, Kimberly

2012-01-01

344

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

345

Impulse Electrotherapy in Reduction Treatment of the Tuboperitoneal Steri  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Aim of investigation is assessment of the impulse electrotherapy clinical effectiveness in a complex treatment of patients with the tuboperitoneal sterility.Materials and methods. A complex clinicolaboratory examination of 114 patients with the tuboperitoneal sterility (TPS) is made. All the females were divided into 3 groups. The females underwent a laparoscopic operation and ultrasonic therapy in the impulse mode to a suprapubic zone in the early postoperative period (10—15 procedures) in...

Belousova, T. E.; Kholmogorova, I. E.

2010-01-01

346

Industrial impulse noise, crest factor and the effect of earmuffs.  

Science.gov (United States)

Noise measurements were taken inside and outside earmuffs worn by 238 workers at 21 industrial plants in order to evaluate exposure to noise and to measure the attenuation by earmuffs used at workplaces. The means of the equivalent noise levels were 93 dB outside the earmuffs and 76 dB inside them. The mean earmuff attenuation was 17 dB. The standard deviations of each of these three values was 6 dB. Thus 90% of the employees wearing earmuffs experienced equivalent noise levels of lower than 85 dB(A) inside the earmuffs. In addition to equivalent noise level, the impulsiveness of the noise was determined based on the cumulative distribution of the crest factor of the signal. The impulse percentage F15 denotes the percentage of the total measurement time when the peak level exceeds the rms level by at least 15 dB. The mean impulse percentage F15 was 1.6% outside earmuffs and 0.8% inside earmuffs. The results showed that earmuffs also attenuated the impulsiveness of noise. The shipyard noise had the highest impulse percentage; the noise in printing plants and papermills had the lowest impulse percentage. PMID:3687731

Pekkarinen, J

1987-10-01

347

[Functional and dysfunctional impulsivity in young binge drinkers].  

Science.gov (United States)

The pattern of binge drinking (BD), found especially among young people, has become an important social and health problem. However, its prevalence has not been carefully studied until recently, together with its consequences in the mid and long run and the possible risk factors. The aim of this work is to study, for the first time, the possible differences in the dimensions of functional and dysfunctional impulsivity in Dickman's model among university students with BD and non-consumers of alcohol or control group. 80 subjects (40 men) with a pattern of BD and 80 controls (40 men) participated in the study, aged 18 to 25 (21,38 ± 1,91). They all completed Dickman's Impulsivity Inventory (DII, 1990). Several variables known to affect the results, such as circadian typology, were controlled for. The scores on dysfunctional impulsivity were higher in the BD group compared to the controls, while no differences were found according to functional impulsivity. Men showed a higher degree of impulsivity than women, both functional and dysfunctional, although in dysfunctional impulsivity this is significant only in the BD group. The DII has proven sensitive to detecting BD, and thus it could become an assessment tool to take into account in preventive or treatment approaches in the future. PMID:22508013

Adan, Ana

2012-01-01

348

High power impulse magnetron sputtering discharge  

International Nuclear Information System (INIS)

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

349

Acoustic radiation force impulse of the liver  

Directory of Open Access Journals (Sweden)

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

Mirko D’Onofrio

2013-01-01

350

Occurrence statistics of magnetic impulsive events  

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Full Text Available In this study, we perform a statistical investigation of magnetic impulse events identified in the Greenland magnetometer stations through the years 1995–2001. We focus on occurrence statistics that can be determined reliably with an automatic event identification procedure. Durin the first two years we observed almost 40% more events than in the following years. Season is not a significant factor in event occurrence. Event occurrence peaks near 12:00 UT, corresponding to approximately 10:00 magnetic local time (MLT at the west coast of Greenland. More events occur prior to local noon than after. Event days are not distributed evenly. Large amplitude events, particularly, tend to appear on consecutive days. Events are observed at lower latitudes at earlier local times in a way consistent with the projection of the outer magnetospheric boundary into the ionosphere. Event latitude depends on dipole tilt angle in a manner similar to that reported for the cusp. Events occur during intervals of enhanced Kp. The main reason for this is that the events themselves contribute to the Kp index. Events exhibit a preference for high solar wind velocity. In particular, the large amplitude events occur during high-speed streams. A slight preference for lower density and more radial interplanetary magnetic fields, as compared to the nominal solar wind distribution, is also observed. However, both the nominal solar wind and event distribution exhibit large differences from year to year, indicating that events occur under a broad range of conditions.

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

T. Moretto

2004-01-01

351

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

352

A new approach to calculating spatial impulse responses  

DEFF Research Database (Denmark)

Using linear acoustics the emitted and scattered ultrasound field can be found by using spatial impulse responses as developed by Tupholme (1969) and Stepanishen (1971). The impulse response is calculated by the Rayleigh integral by summing the spherical waves emitted from all of the aperture surface. The evaluation of the integral is cumbersome and quite involved for different aperture geometries. This paper re-investigates the problem and shows that the field can be found from the crossings between the boundary of the aperture and a spherical wave emitted from the field point onto the plane of the emitting aperture. Summing the angles of the arcs within the aperture readily yields the spatial impulse response for a point in space. The approach makes is possible to make very general calculation routines for arbitrary, flat apertures in which the outline of the aperture is either analytically or numerically defined. The exact field can then be found without evaluating any integrals by merely finding the zerosof the either the analytic or numerically defined functions. This makes it possible to describe the transducer surface using an arbitrary number of lines for the boundary. The approach can also be used for finding analytic solutions to the spatial impulse response for new geometries of, for example, ellipsoidal shape. The approach also makes it easy to incorporate any apodization function and the effect from different transducers baffle mountings. Examples of spatial impulse responses for a shape made from lines bounding the aperture is shown along with solutions for Gaussian apodized round transducer

Jensen, JØrgen Arendt

1997-01-01

353

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

354

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

355

Modulating presence and impulsiveness by external stimulation of the brain  

Directory of Open Access Journals (Sweden)

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

Baumgartner Thomas

2008-08-01

356

Dysfunctional inhibitory control and impulsivity in Internet addiction.  

Science.gov (United States)

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

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

2014-02-28

357

Oscillation in O2 uptake in impulse exercise.  

Science.gov (United States)

The purpose of the present study was to examine 1) whether O(2) uptake (VO(2)) oscillates during light exercise and 2) whether the oscillation is enhanced after impulse exercise. After resting for 1 min on a bicycle seat, subjects performed 5-min pre-exercise with 25 watts work load, 10-s impulse exercise with 200 watts work load and 15-min post exercise with 25 watts work load at 80 rpm. VO(2) during pre-exercise significantly increased during impulse exercise and suddenly decreased and re-increased until 23 s after impulse exercise. In the cross correlation between heart rate (HR) and VO(2) after impulse exercise, VO(2) strongly correlated to HR with a time delay of -4 s. Peak of power spectral density (PSD) in HR appeared at 0.0039 Hz and peak of PSD in VO(2) appeared at 0.019 Hz. The peak of the cross power spectrum between VO(2) and HR appeared at 0.0078 Hz. The results suggested that there is an oscillation in O(2) uptake during light exercise that is associated with the oscillation in O(2) consumption in active muscle. The oscillation is enhanced not only by change in O(2) consumption but also by O(2) content transported from active muscle to the lungs. PMID:24901075

Yano, T; Afroundeh, R; Yamanaka, R; Arimitsu, T; Lian, C S; Shirakawa, K; Yunoki, T

2014-06-01

358

Limitations of using dosimeters in impulse noise environments.  

Science.gov (United States)

The National Institute for Occupational Safety and Health (NIOSH) investigated the capabilities of noise dosimeters to measure personal exposure to impulse noise. The two leading types of commercially available dosimeters were evaluated in terms of their ability to measure and integrate impulses generated from gunfire during live-fire exercises at a law enforcement indoor firing range. Sound measurements were conducted throughout the firing range using dosimeters, sound level meters, and a measurement configuration that consisted of a quarter-inch microphone and a digital audiotape recorder to capture the impulse waveforms. Personal dosimetry was conducted on eight shooters, an observer, and the range master. Peak levels from gunfire reached 163 decibels (dB), exceeding the nominal input limit of the dosimeters. The dosimeters "clipped" the impulses by acting as if the gunfire had a maximum level of 146 dB. In other cases, however, peak levels (e.g., 108 dB) were below the dosimeter input limits, but the dosimeters still showed a peak level of 146 dB. Although NIOSH recommends that sound levels from 80 to 140 dB (A-weighted) be integrated in the calculation of dose and the time-weighted average, our present data suggest this criterion may be inadequate. These results showed that some instruments are incapable of providing accurate measures of impulse sounds because of their electroacoustic limitations. PMID:15238316

Kardous, Chucri A; Willson, Robert D

2004-07-01

359

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

360

Biocontrol in an impulsive predator-prey model.  

Science.gov (United States)

We study a model for biological pest control (or "biocontrol") in which a pest population is controlled by a program of periodic releases of a fixed yield of predators that prey on the pest. Releases are represented as impulsive increases in the predator population. Between releases, predator-pest dynamics evolve according to a predator-prey model with some fairly general properties: the pest population grows logistically in the absence of predation; the predator functional response is either of Beddington-DeAngelis type or Holling type II; the predator per capita birth rate is bounded above by a constant multiple of the predator functional response; and the predator per capita death rate is allowed to be decreasing in the predator functional response and increasing in the predator population, though the special case in which it is constant is permitted too. We prove that, when the predator functional response is of Beddington-DeAngelis type and the predators are not sufficiently voracious, then the biocontrol program will fail to reduce the pest population below a particular economic threshold, regardless of the frequency or yield of the releases. We prove also that our model possesses a pest-eradication solution, which is both locally and globally stable provided that predators are sufficiently voracious and that releases occur sufficiently often. We establish, curiously, that the pest-eradication solution can be locally stable whilst not being globally stable, the upshot of which is that, if we delay a biocontrol response to a new pest invasion, then this can change the outcome of the response from pest eradication to pest persistence. Finally, we state a number of specific examples for our model, and, for one of these examples, we corroborate parts of our analysis by numerical simulations. PMID:25195089

Terry, Alan J

2014-10-01

 
 
 
 
361

FLANN Detector Based Filtering of Images Corrupted by Impulse Noise  

Directory of Open Access Journals (Sweden)

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

Banshidhar Majhi

2005-01-01

362

Dynamic Behaviour of Tension Leg Platform under Impulsive Loading  

Directory of Open Access Journals (Sweden)

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

N. A. Siddiqui

2012-04-01

363

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

364

Fuzzy modelling and impulsive control of the hyperchaotic Lü system  

International Nuclear Information System (INIS)

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

365

Research of Two Different Impulsive Faults of Rolling Element Bearing  

International Nuclear Information System (INIS)

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

366

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

CERN Document Server

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

Fraile-Pelaez, F Javier

2015-01-01

367

An approach to remove impulse noise from a corrupted image  

International Nuclear Information System (INIS)

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

368

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.

Benjamin Oyediran Oyelami

2013-07-01

369

Environmental rearing effects on impulsivity and reward sensitivity.  

Science.gov (United States)

Previous research has indicated that rearing in an enriched environment may promote self-control in an impulsive choice task. To further assess the effects of rearing environment on impulsivity, 2 experiments examined locomotor activity, impulsive action, impulsive choice, and different aspects of reward sensitivity and discrimination. In Experiment 1, rats reared in isolated or enriched conditions were tested on an impulsive choice procedure with a smaller-sooner versus a larger-later reward, revealing that the isolated rats valued the smaller-sooner reward more than the enriched rats. A subsequent reward challenge was presented in which the delay to the 2 rewards was the same but the magnitude difference remained. The enriched rats did not choose the larger reward as often as the isolated rats, reflecting poorer reward discrimination. Impulsive action was assessed using a differential-reinforcement-of-low-rate task, which revealed deficits in the enriched rats. In Experiment 2, rats reared in isolated, standard, or enriched conditions were tested on reward contrast and reward magnitude sensitivity procedures. The rats were presented with 2 levers that delivered different magnitudes of food on variable interval 30-s schedules. Across all tests, the enriched and social rats displayed more generalized responding to the small-reward lever, but a similar response to the large-reward lever, compared with the isolated rats. This confirmed the results of Experiment 1, indicating poorer reward discrimination in the enriched condition compared with the isolated condition. The results suggest that enrichment may moderate reward generalization/discrimination processes through alterations in incentive motivational processes. PMID:24128360

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

2013-10-01

370

Impulse Electrotherapy in Reduction Treatment of the Tuboperitoneal Steri  

Directory of Open Access Journals (Sweden)

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

T.E. Belousova

2010-03-01

371

Transthoracic Cardiac Acoustic Radiation Force Impulse Imaging  

Science.gov (United States)

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

Bradway, David Pierson

372

The Impulse Response of an Exponential Assembly  

International Nuclear Information System (INIS)

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

373

Fast Impulse Noise Removal from Highly Corrupted Images  

CERN Document Server

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

Hosseini, Hossein

2011-01-01

374

Oscillation of a Linear Delay Impulsive Differential Equation  

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The main result of the paper is that the oscillation (non-oscillation) of the impulsive delay differential equation $\\dot {x}(t)+\\sum_{k=1}^m A_k(t)x[h_k(t)]=0,~~t\\geq 0$, $x(\\tau_j)=B_jx(\\tau_j-0), \\lim \\tau_j = \\infty$ is equivalent to the oscillation (non-oscillation) of the equation without impulses $\\dot {x}(t)=\\sum_{k=1}^m A_k(t) \\prod_{h_k(t)<\\tau_j\\leq t} B_j^{-1}x[h_k(t)]=0, t \\geq 0$. Explicit oscillation results are presented.

Berezansky, L.; Braverman, E.

1995-01-01

375

Impulsive differential equations asymptotic properties of the solutions  

CERN Document Server

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

Bainov, DD

1995-01-01

376

Enhanced-SNR Impulse Radio Transceiver based on Phasers  

CERN Document Server

The concept of SNR enhancement in impulse radio transceivers based on phasers of opposite chirping slopes is introduced. It is shown that signal to-noise radio (SNR) enhancements by factors M2 and M are achieved for burst noise and Gaussian noise, respectively, where M is the stretching factor of the phasers. An experimental demonstration is presented, using stripline cascaded C-section phasers, where SNR enhancements in agreement with theory are obtained. The proposed radio analog signal processing transceiver system is simple, low-cost and frequency scalable, and may therefore be suitable for broadband impulse radio ranging and communication applications.

Nikfal, Babak; Caloz, Christophe

2014-01-01

377

Room impulse responses measurement using a moving microphone  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, we present a technique to record a large set of room impulse responses using a microphone moving along a tra jectory. The technique processes the signal recorded by the microphone to reconstruct the signals that would have been recorded at all possible spatial positions along the array. The speed of movement of the microphone is shown to be the key factor for the reconstruction. This fast method of recording spatial impulse responses can also be applied for the recording of hea...

Ajdler, Thibaut; Sbaiz, Luciano; Vetterli, Martin

2006-01-01

378

Impulsive Exponential Consensus of Multi-agent Nonlinear Fuzzy Systems  

Directory of Open Access Journals (Sweden)

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

Liping Zhang

2013-01-01

379

Exponential stability in Hopfield-type neural networks with impulses  

Energy Technology Data Exchange (ETDEWEB)

This paper demonstrates that there is an exponentially stable unique equilibrium state in a Hopfield-type neural network that is subject to quite large impulses that are not too frequent. The activation functions are assumed to be globally Lipschitz continuous and unbounded. The analysis exploits an homeomorphic mapping and an appropriate Lyapunov function, and also either a geometric-arithmetic mean inequality or a Young inequality, to derive a family of easily verifiable sufficient conditions for convergence to the unique globally stable equilibrium state. These sufficiency conditions, in the norm -parallel .-parallel {sub p} where p {>=} 1, include those governing the network parameters and the impulse magnitude and frequency.

Mohamad, Sannay [Department of Mathematics, Faculty of Science, Universiti Brunei Darussalam, Jalan Tunku Link BE1410 (Brunei Darussalam)]. E-mail: sannay@fos.ubd.edu.bn

2007-04-15

380

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

International Nuclear Information System (INIS)

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

 
 
 
 
381

Impulsive and hybrid dynamical systems stability, dissipativity, and control  

CERN Document Server

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

Haddad, Wassim M; Nersesov, Sergey G

2014-01-01

382

The detection of the X ray blow off impulses under the condition of intense nuclear radiation and its anti-radiation electronic studies  

International Nuclear Information System (INIS)

The detecting studies of the blow off impulses produced in the flat targets irradiated by nuclear explosion X ray are discussed. In detections, the detector principle of directly measuring the specific series of time intervals and variable reluctance transducing technique were used. A set of effective methods of anti-radiative interference are adopted in the whole detecting system. In addition, the moving frictions of the target groups are calibrated on the equipment of powder gun. Finally, the comparisons between the detective data and the computed results about the X ray blow off impulses are given. The results indicate that they coincide with each other satisfactorily

383

Obtaining Binaural Room Impulse Responses from B-Format Impulse Responses Using Frequency-Dependent Coherence Matching  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Measuring binaural room impulse responses (BRIRs) for different rooms and different persons is a costly and time-consuming task. In this paper, we propose a method that allows to compute BRIRs from a B-format room impulse response (B-format RIR) and a set of head-related transfer functions (HRTFs). This enables to measure the room-related properties and head-related properties of BRIRs separately, reducing the amount of measurements necessary for obtaining BRIRs for different rooms and differ...

Menzer, F.; Faller, C.; Lissek, H.

2011-01-01

384

Carrion crows cannot overcome impulsive choice in a quantitative exchange task.  

Science.gov (United States)

The ability to control an immediate impulse in return for a more desirable - though delayed - outcome has long been thought to be a uniquely human feature. However, studies on non-human primates revealed that some species are capable of enduring delays in order to get food of higher quality or quantity. Recently two corvid species, common raven (Corvus corax) and carrion crow (Corvus corone corone), exchanged food for a higher quality reward though seemed less capable of enduring delays when exchanging for the same food type in a higher quantity. In the present study, we specifically investigated the ability of carrion crows to overcome an impulsive choice in a quantitative exchange task. After a short delay, individuals were asked to give back an initial reward (cheese) to the human experimenter in order to receive a higher amount of the same reward (two, four, or eight pieces). We tested six captive crows - three individuals never exchanged the initial reward for a higher quantity; the other three birds did exchange though at very low rates. We performed a preference test between one or more pieces of cheese in order to address whether crow poor performance could be due to an inability to discriminate between different quantities or not attributing a higher value to the higher quantities. All birds chose the higher quantities significantly more often, indicating that they can discriminate between quantities and that higher quantities are more desirable. Taken together, these results suggest that, although crows may possess the cognitive abilities to judge quantities and to overcome an impulsive choice, they do so only in order to optimize the qualitative but not quantitative output in the exchange paradigm. PMID:22529833

Wascher, Claudia A F; Dufour, Valerie; Bugnyar, Thomas

2012-01-01

385

Carrion crows cannot overcome impulsive choice in a quantitative exchange task  

Directory of Open Access Journals (Sweden)

Full Text Available The ability to control an immediate impulse for a future, more preferred outcome has long been thought to be a uniquely human feature. However, studies on non-human primates revealed that some monkeys and apes are capable of enduring delays to get a more preferred food and/or more food of the same kind. Recently two corvid species, the common raven (Corvus corax and carrion crow (Corvus corone corone, exchanged food for a better quality reward, whereas they seemed to have difficulties to do so for a higher quantity. In the present study we specifically investigated carrion crows’ ability to overcome an impulsive choice in a quantitative exchange task. After a short delay, individuals were asked to give back an initial reward (cheese to the human experimenter in order to receive a higher amount of the same reward (2, 4 or 8 pieces. We successfully tested six captive crows. Three individuals never exchanged one piece of cheese against a higher quantity; the other three birds did exchange at very low rates. In order to rule out, that crows’ poor performance is due to the fact that they cannot discriminate between different quantities or that they do not attribute a higher value to higher quantities, we performed a preference test between one and more pieces of cheese. All birds chose the higher quantities significantly more often, indicating that they can discriminate between quantities and that higher quantities actually have a value for them. Taken together, these results suggest that, although crows may possess the cognitive abilities to judge quantities and to overcome an impulsive choice, they do so only in order to optimize the qualitative but not quantitative output in the exchange paradigm.

ThomasBugnyar

2012-04-01

386

Construction and enlargement of dilatonic wormholes by impulsive radiation  

CERN Document Server

The dynamical behavior of traversable wormholes and black holes under impulsive radiation is studied in an exactly soluble dilaton gravity model. Simple solutions are presented where a traversable wormhole is constructed from a black hole, or the throat of a wormhole is stably enlarged or reduced. These solutions illustrate the basic operating principles needed to construct similar analytic solutions in full Einstein gravity.

Koyama, H; Kim, S W; Koyama, Hiroko; Hayward, Sean A.; Kim, Sung-Won

2003-01-01

387

The Chaotification of Discrete Hopfield Neural Networks via Impulsive Control  

International Nuclear Information System (INIS)

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

388

Periodic solutions of nonautonomous cellular neural networks with impulses  

International Nuclear Information System (INIS)

Sufficient conditions are obtained for the existence and global exponential stability of a unique periodic solution of a class of neural networks with impulses by using Mawhin's continuation theorem of coincidence degree theory and constructing Lyapunov functions. An illustrative example is given to demonstrate the effectiveness of the obtained results

389

Cognitive Processes in the Reflective-Impulsive Cognitive Style  

Science.gov (United States)

In this study, the authors improved the understanding of the cognitive processes underlying the reflective-impulsive cognitive style (RI), which was initially measured by J. Kagan, B. L. Rosman, D. Day, J. Albert, and W. Phillips (1964) on the Matching Familiar Figures Test (MFFT). The authors determined the relationships between the RI style and…

Rozencwajg, Paulette; Corroyer, Denis

2005-01-01

390

Analysis of a developed analog trilateration system of impulsive sounds  

Science.gov (United States)

A characterization study is made from a trilateration system for impulsive sounds, in which theoretical analysis and experimental results are presented. This system uses an analog trilateration method, avoiding to implement high frequency ADC conversion elements. It also presents the optimization of the chosen array of microphones, thus allowing for a better trilateration algorithm behavior.

López R., Juan Manuel; Marulanda B., Jose Ignacio

2014-05-01

391

Bifurcations of planar Hamiltonian systems with impulsive perturbation  

CERN Document Server

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

Hu, Zhaoping; Romanovski, Valery G

2011-01-01

392

Cone-valued impulsive differential and integrodifferential inequalities  

Directory of Open Access Journals (Sweden)

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

Sam Olatunji Ale

2005-06-01

393

Dwell-time conditions for robust stability of impulsive systems  

CERN Document Server

We prove that impulsive systems, which possess an ISS Lyapunov function, are ISS for 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, which satisfy the generalized average dwell-time condition.

Dashkovskiy, Sergey

2012-01-01

394

Impulse response modeling of indoor radio propagation channels  

Science.gov (United States)

If indoor radio propagation channels are modeled as linear filters, they can be characterized by reporting the parameters of their equivalent impulse response functions. In this paper, the measurement and modeling of estimates for such functions in two different office buildings are reported. The resulting data base consists of 12,000 impulse response estimates of the channel, which are obtained by inverse Fourier transforming or the channel's transfer functions. Major results of the analysis are as follows. (1) The number of multipath components in each impulse response estimate is a normally-distributed random variable with a mean value that increases with increasing antenna separations. (2) A 'modified Poisson' distribution shows a good fit to the arrival time of the multipath components. (3) Amplitudes are normally distributed over both local and global areas, with a log-mean value that decreases almost linearly with increasing excess delay. (4) For small displacements of the receiving antenna, the amplitude of the multipath components are correlated; the correlation coefficient is a decreasing function of both displacement of the antenna position and excess delay. (5) The amplitudes of adjacent multipath components of the same impulse response function show negligible correlations. (6) The rms delay spread over large areas is normally distributed with mean values that increase with increasing antenna separation. The average rms delay spread for each location has great linear dependence with the average path loss for that location. Results reported in this paper can be used in the simulation of indoor radio propagation channels.

Hashemi, Homayoun

1993-09-01

395

Periodic components of hand acceleration/deceleration impulses during telemanipulation  

International Nuclear Information System (INIS)

Responsiveness is the ability of a telemanipulator to recreate user trajectories and impedance in time and space. For trajectory production, a key determinant of responsiveness is the ability of the system to accept user inputs, which are forces on the master handle generated by user hand acceleration/deceleration (a/d) impulses, and translate them into slave arm acceleration/deceleration. This paper presents observations of master controller a/d impulses during completion of a simple target acquisition task. Power spectral density functions (PSDF's) calculated from hand controller a/d impulses were used to assess impulse waveform. The relative contributions of frequency intervals ranging up to 25 Hz for three spatially different versions of the task were used to determine which frequencies were most important. The highest relative power was observed in frequencies between 1 Hz and 6 Hz. The key frequencies related to task difficulty were in the range from 2 Hz to 8 Hz. the results provide clues to the source of the performance inhibition

396

Solar Flare Impulsive Phase Emission Observed with SDO/EVE  

CERN Document Server

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

Kennedy, Michael B; Mathioudakis, Mihalis; Keenan, Francis P

2013-01-01

397

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Impulsivity plays a key role in decision-making under uncertainty. It is a significant contributor to problem and pathological gambling. Standard assessments of impulsivity by questionnaires, however, have various limitations, partly because impulsivity is a broad, multi-faceted concept. What remains unclear is which of these facets contribute to shaping gambling behavior. In the present study, we investigated impulsivity as expressed in a gambling setting by applying computational modeling t...

Saee Paliwal; Anna Katharina Schmitz; Klaas Enno Stephan

2014-01-01

398

Impulsivity and pathological gambling among Chinese: is it a state or a trait problem?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

BACKGROUND: This study tested 37 Chinese male pathological gamblers and 40 controls to understand the relationship between pathological gambling and impulsivity as a long-term trait or a short-term state in the cognitive and affective domain. RESULTS: Trait impulsivity was measured by the Barratt Impulsiveness Scale-11. State impulsivity in the cognitive and affective domains were measured by the Stroop Color Word Test and the Emotional Conflict Task, respectively. The pathological gamblers s...

Lai, Fdm; Ip, Aky; Lee, Tmc

2011-01-01

399

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Background This study tested 37 Chinese male pathological gamblers and 40 controls to understand the relationship between pathological gambling and impulsivity as a long-term trait or a short-term state in the cognitive and affective domain. Results Trait impulsivity was measured by the Barratt Impulsiveness Scale-11. State impulsivity in the cognitive and affective domains were measured by the Stroop Color Word Test and the Emotional Conflict Task, res...

Dm, Lai Florence; Ky, Ip Alison; Mc, Lee Tatia

2011-01-01

400

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

International Nuclear Information System (INIS)

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

 
 
 
 
401

Existence and uniqueness of periodic solutions of nonautonomous cellular neural networks with impulses  

International Nuclear Information System (INIS)

By using the continuation theorem of Mawhin's coincidence degree theory and some analysis techniques, some new sufficient conditions are obtained ensuring existence, uniqueness and global exponential stability of periodic solution of nonautonomous cellular neural networks with impulses. The results extend earlier ones where impulses are absent. Further, using numerical simulation method the influences of the impulsive perturbations on the inherent oscillation are investigated

402

Invariant Probability Measures and Non-wandering Sets for Impulsive Semiflows  

Science.gov (United States)

We consider impulsive dynamical systems defined on compact metric spaces and their respective impulsive semiflows. We establish sufficient conditions for the existence of probability measures which are invariant under such impulsive semiflows. Under these conditions we also deduce the forward invariance of their non-wandering sets except the discontinuity points.

Alves, José F.; Carvalho, Maria

2014-12-01

403

A scalable piezoelectric impulse-excited energy harvester for human body excitation  

International Nuclear Information System (INIS)

Harvesting energy from low-frequency and non-harmonic excitations typical of human motion presents specific challenges. While resonant devices do have an advantage in environments where the excitation frequency is constant, and while they can make use of the entire proof mass travel range in the case of excitation amplitudes that are smaller than the internal displacement limit, they are not suitable for body applications since the frequencies are random and the amplitudes tend to be larger than the device size. In this paper a piezoelectric, impulse-excited approach is presented. A cylindrical proof mass actuates an array of piezoelectric bi-morph beams through magnetic attraction. After the initial excitation these transducers are left to vibrate at their natural frequency. This increases the operational frequency range as well as the electromechanical coupling. The principle of impulse excitation is discussed and a centimetre-scale functional model is introduced as a proof of concept. The obtained data show the influence of varying the frequency, acceleration and proof mass. Finally, a commercially available integrated circuit for voltage regulation is tested. At a frequency of 2 Hz and an acceleration of 2.7 m s?2 a maximal power output of 2.1 mW was achieved. (paper)

404

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

International Nuclear Information System (INIS)

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

405

Rapid Vaporization of Thin Conductors Used for Impulse Metalworking  

Science.gov (United States)

Forming, cutting and welding of metal by impulse has significant advantages, in that short time scales change the fundamental nature of the forming process and short duration impulses can be used with much lighter and more agile equipment because large static forces do not need to be resisted. Impulse metalworking is commonly implemented using explosives or electromagnetic actuators. Explosives have limitations such as space requirements, handling and storage restrictions and ability to scale down the process. The application of electromagnetic forming is limited at high energies and large numbers of operations by the availability of long-lived electromagnetic coils (or actuators, as they are sometimes referred to). Here low-cost, disposable actuators have been suggested as one method to treat this issue. Forming, cutting and welding of metal by impulse has significant advantages, in that short time scales change the fundamental nature of the forming process and short duration impulses can be used with much lighter and more agile equipment because large static forces do not need to be resisted. Impulse metalworking is commonly implemented using explosives or electromagnetic actuators. Explosives have limitations such as space requirements, handling and storage restrictions and ability to scale down the process. The application of electromagnetic forming is limited at high energies and large numbers of operations by the availability of long-lived electromagnetic coils (or actuators, as they are sometimes referred to). Here low-cost, disposable actuators have been suggested as one method to treat this issue. Applications including cutting, forming, axisymmetric joining and collision welding are demonstrated and discussed. From analysis of the data from these applications, it was seen that degree of confinement has a great effect on effective geometries of a vaporizing foil. With less confinement, thicker foils were found to be more efficient whereas thinner foils were found to be more effective for the applications which require less confinement pressure on the foil. Collision welding of a wide range of dissimilar metals was implemented and mechanical testing yielded a wide spectrum of results. Optical micrographs of the weld interfaces also showed a wide range of morphology. A device called linear perforator has been created to use the pressure created by vaporizing wire and detonation of a chemical augment surrounding it, to launch a 3.174 mm thick, 25.4 mm tall and 152.4 mm long steel projectile to velocities close to 400 m/s. This projectile is used to fully penetrate 12.7 mm thick artillery shells made of steel. Design of the linear perforator and latest results will be discussed.

Vivek, Anupam

406

Case-control study of allele frequencies of 15 short tandem repeat loci in males with impulsive violent behavior  

Science.gov (United States)

Background Analysis of genetic polymorphisms in short tandem repeats (STRs) is an accepted method for detecting associations between genotype and phenotype but it has not previously been used in the study of the genetics of impulsive violent behavior. Objective Compare the prevalence of different polymorphisms in 15 STR loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818 and FGA) between men with a history of impulsive violence and male control subjects without a history of impulsive violence. Methods The distributions of the alleles of the 15 STR loci were compared between 407 cases with impulsive violent behavior and 415 controls using AmpFlSTR® Identifiler™ kits. Results Compared to controls, the average frequencies of the following alleles were significantly lower in individuals with a history of violent behavior: allele 10 of TH01 (OR=0.29, 95%CI=0.16-0.52, p<0.0001,), allele 8 of TPOX (OR=0.71, 95%CI=0.58-0.86, p=0.0005), allele 9 of TPOX (OR=0.65, 95%CI=0.47-0.89, p=0.0072) and allele 14 of CSF1PO (OR=0.27, 95%CI=0.11-0.68, p=0.0035). One allele was significantly higher in cases than controls: allele 11 of TPOX (OR=1.79, 95%CI=1.45-2.22, p<0.0001). Conclusions To the best of our knowledge, this is the first behavioral genetic study that clearly demonstrates a close relationship between specific genetic markers and impulsive aggression in non-psychiatric offenders. Further prospective work will be needed to determine whether or not the alleles identified can be considered risk factors for impulsive aggression and, if so, the underlying mechanisms that result in this relationship. PMID:24991178

Yang, Chun; Ba, Huajie; Gao, Zhiqin; Zhao, Hanqing; Yu, Haiying; Guo, Wei

2013-01-01

407

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

Science.gov (United States)

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

Qi, Jiangtao; Li, Chuandong; Huang, Tingwen

2014-10-01

408

An elegant impulser developed for flat beam injection  

International Nuclear Information System (INIS)

The following report describes the design, construction, and checkout of a high-voltage (HV) impulser built for the heavy ion fusion (HIF) project [1]. The purpose of this impulser is to provide an adjustable diode voltage source of sufficient quality and level to allow the optimization of beam transport and accelerator sections of HIF [2, 3]. An elegant, low-impedance, high-energy storage capacitor circuit has been selected for this application. Circuit parameters of the retrofit to the diode region [4] have been included to provide the controlled rise time. The critical part of this circuit that is common to all candidates is the impedance matching component. The following report provides a description of the implemented circuit, the basic circuit variables for wave shaping, screening techniques revealing the weakest circuit component, and the resulting output of the injector

409

Heavy ion fusion (HIF) impulse injector design, construction, and checkout  

Energy Technology Data Exchange (ETDEWEB)

The following report describes the design, construction, and checkout of a high-voltage (HV) impulser built for the heavy ion fusion (HIF) project. The purpose of this impulser is to provide an adjustable diode voltage source of sufficient quality and level to allow the optimization of beam transport and accelerator sections of HIF. An elegant, low-impedance, high-energy storage capacitor circuit has been selected for this application. A retrofit to the diode region has been included to provide additional beam stability and a controlled rise time. The critical part of this circuit that is common to all candidates is the impedance matching component. The following report provides a description of the implemented circuit, the basic circuit variables for wave shaping, component screening techniques, resulting operating parameters, diode modifications, operating considerations, and fault protection.

Wilson, M. J., LLNL

1998-05-04

410

Simulation Analysis and Design for the Pressure Impulse Test  

Directory of Open Access Journals (Sweden)

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

Yuan Zhaohui

2012-01-01

411

Impulse generated during unsteady maneuvering of swimming fish  

Science.gov (United States)

The relationship between the maneuvering kinematics of a Giant Danio (Danio aequipinnatus) and the resulting vortical wake is investigated for a rapid, 'C'-start maneuver using fully time-resolved (500 Hz) particle image velocimetry (PIV). PIV illuminates the two distinct vortices formed during the turn. The fish body rotation is facilitated by the initial, or "maneuvering" vortex formation, and the final fish velocity is augmented by the strength of the second, "propulsive" vortex. Results confirm that the axisymmetric vortex ring model is reasonable to use in calculating the hydrodynamic impulse acting on the fish. The total linear momentum change of the fish from its initial swimming trajectory to its final swimming trajectory is balanced by the vector sum of the impulses of both vortex rings. The timing of vortex formation is uniquely synchronized with the fish motion, and the choreography of the maneuver is addressed in the context of the resulting hydrodynamic forces.

Epps, Brenden P.; Techet, Alexandra H.

412

Spatial impulse responses from a flexible baffled circular piston.  

Science.gov (United States)

The theory of orthogonal polynomial (Zernike) expansions of functions on a disk, as used in the diffraction theory of optical aberrations, is applied to obtain (semi-) analytical expressions for the spatial impulse responses arising from a non-uniformly moving, baffled, circular piston. These expressions are in terms of the expansion coefficients of the non-uniformity and the responses of the orthogonal expansion functions. The latter impulse responses have a closed form as finite series involving the Legendre functions and the sinc function. The method is compared with a similar method, proposed by P. R. Stepanishen [J. Acoust. Soc. Am. 70, 1176-1181 (1981)] where zeroth order orthogonal Bessel functions, rather than Zernike polynomials, are used as expansion functions. PMID:21568398

Aarts, Ronald M; Janssen, Augustus J E M

2011-05-01

413

Fuzzy Impulsive Control of Permanent Magnet Synchronous Motors  

International Nuclear Information System (INIS)

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

414

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

International Nuclear Information System (INIS)

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

415

Problems Related to Bootstrapping Impulse Responses of Autoregressive Processes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Bootstrap confidence intervals for impulse responses computed from autoregressive processes are considered. A detailed analysis of the methods in current use shows that they are not very reliable in some cases. In particular, there are theoretical reasons for them to have actual coverage probabilities which deviate considerably from the nominal level in some situations of practical importance. For a simple case alternative bootstrap methods are proposed which provide correct results asymptoti...

Benkwitz, Alexander; Lu?tkepohl, Helmut; Neumann, Michael H.

1997-01-01

416

Anomalous electron transport in high power impulse magnetron sputtering  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Oscillating electric fields in the megahertz range have been studied in a high power impulse magnetron sputtering (HIPIMS) plasma with the use of electric field probe arrays. One possible reason for these oscillations to occur is charge perturbation—or so-called modified two-stream instabilities (MTSIs). It is known that MTSIs give rise to acceleration of the charged plasma species and can give a net transport of electrons across the magnetic field lines. Measurements of these oscillations ...

Lundin, Daniel; Helmersson, Ulf; Kirkpatrick, Scott; Rohde, Suzanne; Brenning, Nils

2008-01-01

417

Simulation Analysis and Design for the Pressure Impulse Test  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The pressure impulse test system is a complex nonlinear system; its control methods are very different from the traditional linear systems. The difficulty of its analysis focused on the physical realization of the entire system and mathematical model on complex pipeline system. We analyze the composition and principles of the entire test system, detailed study the basic equation of unsteady flow and do the static design which provides parameters for the dynamic simulation. Method of character...

Yuan Zhaohui; Zhao Kaiyu

2012-01-01

418

Planar elliptically shaped dipole antenna for UWB Impulse Radio:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The goal of this thesis was to develop design concepts of the UWB antenna with improved characteristics for impulse radio applications. To reach this goal a number of theoretical and experimental investigations were carried out. The major result of the thesis is a number of novel concepts for UWB antennas including: - The shielded elliptically-shaped dipole; - The active UWB antenna with an integrated pulse generator on chip; - The differential feeding of balanced UWB antennas via a shie...

Vorobyov, A. V.

2008-01-01

419

Naked Singularities, Cosmic Time Machines and Impulsive Events  

CERN Document Server

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

De Felice, F

2007-01-01

420

Optimal Waveforms Design for Ultra-Wideband Impulse Radio Sensors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ultra-wideband impulse radio (UWB-IR) sensors should comply entirely with the regulatory spectral limits for elegant coexistence. Under this premise, it is desirable for UWB pulses to improve frequency utilization to guarantee the transmission reliability. Meanwhile, orthogonal waveform division multiple-access (WDMA) is significant to mitigate mutual interferences in UWB sensor networks. Motivated by the considerations, we suggest in this paper a low complexity pulse forming technique, and i...

Chong Zhao; Bin Li; Zheng Zhou; Dejian Li; Weixia Zou

2010-01-01

 
 
 
 
421

Impulse Volt-Time Characteristics of Oil and OIP Insulation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Estimation of insulation strength of transformer oil and Oil Impregnated Paper (OIP) insulation, which constitutes major portion of insulation in power transformer, is an important task. Also, it is often necessary to evaluate the breakdown strength of oil and OIP under non-standard impulse voltages, since the oil and OIP insulation is subjected to non-standard waveshapes between inter-disc and inter-turn insulation. This necessitates for a generalized model to estimate th...

Venkatesan, S.; Usa, S.

2005-01-01

422

Almost Periodic Solutions for Impulsive Fractional Stochastic Evolution Equations  

Directory of Open Access Journals (Sweden)

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

Toufik Guendouzi

2014-08-01

423

Enhanced-SNR Impulse Radio Transceiver based on Phasers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The concept of SNR enhancement in impulse radio transceivers based on phasers of opposite chirping slopes is introduced. It is shown that signal to-noise radio (SNR) enhancements by factors M2 and M are achieved for burst noise and Gaussian noise, respectively, where M is the stretching factor of the phasers. An experimental demonstration is presented, using stripline cascaded C-section phasers, where SNR enhancements in agreement with theory are obtained. The proposed radio...

Nikfal, Babak; Zhang, Qingfeng; Caloz, Christophe

2014-01-01

424

Subtyping pathological gamblers based on impulsivity, depression and anxiety  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Ledgerwood, David M.; Petry, Nancy M.

2010-01-01

425

On Heat and Paper : From Hot Pressing to Impulse Technology  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Lucisano, Marco Francesco Carlo

2002-01-01

426

Real-time acoustic radiation force impulse imaging  

Science.gov (United States)

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

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

2005-04-01

427

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2011-01-01

428

Acoustic Radiation Force Impulse Imaging of Human Prostates ex vivo  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2010-01-01

429

A Parallel Tracking Method for Acoustic Radiation Force Impulse Imaging  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2007-01-01

430

Impulsive and Compulsive Behaviors in Parkinson’s Disease  

Science.gov (United States)

Background: Impulsive and compulsive behaviors (ICBs) are a heterogeneous group of conditions that may be caused by long-term dopaminergic replacement therapy (DRT) of Parkinson’s disease (PD). The spectrum of ICBs includes dopamine dysregulation syndrome (DDS), punding, and impulse control disorders (ICDs). Contents: We made a detailed review regarding the epidemiology, pathology, clinical characteristics, risk factors, diagnosis as well as treatment of ICBs. Results: The prevalence of ICBs in PD patients is approximately 3–4% for DDS, 0.34–4.2% for punding, and 6–14% for ICDs, with higher prevalence in Western populations than in Asian. Those who take high dose of levodopa are more prone to have DDS, whereas, ICDs are markedly associated with dopamine agonists. Different subtypes of ICBs share many risk factors such as male gender, higher levodopa equivalent daily dose, younger age at PD onset, history of alcoholism, impulsive, or novelty-seeking personality. The Questionnaire for Impulsive–Compulsive Disorder in Parkinson’s Disease-Rating Scale seems to be a rather efficacious instrument to obtain relevant information from patients and caregivers. Treatment of ICBs is still a great challenge for clinicians. Readjustment of DRT remains the primary method. Atypical antipsychotics, antidepressants, amantadine, and psychosocial interventions are also prescribed in controlling episodes of psychosis caused by compulsive DRT, but attention should be drawn to balance ICBs symptoms and motor disorders. Moreover, deep brain stimulation of the subthalamic nucleus might be a potential method in controlling ICBs. Conclusion: The exact pathophysiological mechanisms of ICBs in PD remains poorly understood. Further researches are needed not only to study the pathogenesis, prevalence, features, and risk factors of ICBs, but to find efficacious therapy for patients with these devastating consequences. PMID:25452726

Zhang, Guoxin; Zhang, Zhentao; Liu, Ling; Yang, Jiaolong; Huang, Jinsha; Xiong, Nian; Wang, Tao

2014-01-01

431

Impulsive Hybrid Discrete-Continuous Delay Differential Equations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Lenz, Simon Manfred

2014-01-01

432

Volatility impulse response functions for multivariate GARCH models  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Hafner, Christian; Herwatz, Helmut

2001-01-01

433

On Integrable Solutions of Impulsive Delay Differential Equations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The connection of function properties of solutions with exponential stability of linear impulsive differential equation $$\\dot{x} (t) - \\sum_{k=1}^m {A_k (t) x[h_k(t)]} = r(t),~ t \\geq 0, x(\\xi ) = \\varphi (\\xi),~ \\xi < 0,$$ $$x(\\tau_j) = B_j x(\\tau_j - 0) , ~j=1,2, \\dots .$$ The explicit stability results and sufficient conditions for existence of integrable solutions are presented.

Berezansky, L.; Braverman, E.

1994-01-01

434

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

Science.gov (United States)

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

Howell, W. M.

1985-09-01

435

Gronwall-type integral inequalities with impulses on time scales  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract In this article, some Gronwall-type integral inequalities with impulses on time scales are investigated. Our results extend some known dynamic inequalities on time scales, unify and extend some continuous inequalities and their corresponding discrete analogues. Some applications of the main results are given in the end of this article. AMS (MOS Subject Classification 34D09; 34D99, 37M10, 35D05, 49K25, 90C46.

Kang Ying

2011-01-01

436

Dynamic pressure measurements in high power impulse magnetron sputtering  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A microphone has been used to measure the dynamic pressure inside a vacuum chamber during high power impulse magnetron sputtering with high enough time-resolution (~µs) to track the pressure change during the discharge pulse. An experimental measurement of the dynamic pressure is of interest since it would give information about gas depletion, which is believed to dramatically alter the plasma discharge characteristics. This investigation has shown that the magnitude of the pressure wave, wh...

Forse?n, Rikard

2009-01-01

437

Eroding ribbon thermocouples: impulse response and transient heat flux analysis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have investigated a particular type of fast-response surface thermocouple to determine if it is appropriate to use a one-dimensional transient heat conduction model to derive the transient surface heat flux from the measurements of surface temperature. With these sensors, low thermal inertia thermocouple junctions are formed near the surface by abrasive wear. Using laser excitation, we obtained the impulse response of these commercially available devices. The response of particular sensors...

Buttsworth, Dr; Stevens, R.; Stone, Cr

2005-01-01

438

Model Checking Markov Reward Models with Impulse Rewards  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper considers model checking of Markov reward models (MRMs), continuous-time Markov chains with state rewards as well as impulse rewards. The reward extension of the logic CSL (continuous stochastic logic) is interpreted over such MRMs, and two numerical algorithms are provided to check the reachability of a set of goal states under a time and an accumulated reward constraint. This extends existing model-checking techniques for MRMs with just state rewards, and improves the applicabili...

Cloth, L.; Katoen, J. P.; Maneesh Khattri, M.; Pulungan, R.

2005-01-01

439

Review of Impulse Noise Removal from Digital Video  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

RAVINDRA LUHACH; SHELEJ KHERA

2013-01-01

440

An Impulse Response Function for Evaluation of UWB SAR Imaging  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Based on analysis of a point target imaged by different synthetic aperture radar (SAR) systems, the commonly used impulse response function in SAR Imaging (IRF-SAR)—a two-dimensional (2-D) sinc function—is shown to be inappropriate for ultrawideband-ultrawi