WorldWideScience
 
 
1

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

International Nuclear Information System (INIS)

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

2004-01-01

2

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

3

Domain-specific impulsivity in school-age children.  

UK PubMed Central (United Kingdom)

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 report card grades. Implications for theoretical conceptions of impulsivity as well as for practical applications (e.g. domain-specific interventions) are discussed.

Tsukayama E; Duckworth AL; Kim B

2013-11-01

4

HTS Magnets for Advanced Magnetoplasma Space Propulsion Applications  

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-07-12

5

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1991-01-01

6

Impulse control, diabetes-specific self-efficacy, and diabetes management among emerging adults with type 1 diabetes.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To explore the relationships among impulse control, diabetes-specific self-efficacy, and diabetes management behaviors among emerging adults with type 1 diabetes. METHODS: A total of 204 high school seniors (M = 18.25 years, SD = .45, 55.9% females) with type 1 diabetes self-reported on impulse control, diabetes-specific self-efficacy, and diabetes management behaviors during the past 3 months. Mediation and path analyses were used to address aims. RESULTS: Greater impulse control was associated with better diabetes management among these emerging adults. In addition, diabetes-specific self-efficacy partially mediated the relationship between impulse control and diabetes management. CONCLUSIONS: Impulse control and diabetes-specific self-efficacy may be important in the management of type 1 diabetes among emerging adults. Diabetes-specific self-efficacy may play an important role in successful diabetes management among youth with lower impulse control.

Stupiansky NW; Hanna KM; Slaven JE; Weaver MT; Fortenberry JD

2013-04-01

7

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

International Nuclear Information System (INIS)

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

2011-01-01

8

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

Science.gov (United States)

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

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

2008-04-01

9

A study of variable thrust, variable specific impulse trajectories for solar system exploration  

Science.gov (United States)

A study has been performed to determine the advantages and disadvantages of variable thrust and variable Isp (specific impulse) trajectories for solar system exploration. There have been several numerical research efforts for variable thrust, variable Isp, power-limited trajectory optimization problems. All of these results conclude that variable thrust, variable Isp (variable specific impulse, or VSI) engines are superior to constant thrust, constant Isp (constant specific impulse; or CSI) engines. However, most of these research efforts assume a mission from Earth to Mars, and some of them further assume that these planets are circular and coplanar. Hence they still lack the generality. This research has been conducted to answer the following questions: (1) Is a VSI engine always better than a CSI engine or a high thrust engine for any mission to any planet with any time of flight considering lower propellant mass as the sole criterion? (2) If a planetary swing-by is used for a VSI trajectory, is the fuel savings of a VSI swing-by trajectory better than that of a CSI swing-by or high thrust swing-by trajectory? To support this research, an unique, new computer-based interplanetary trajectory calculation program has been created. This program utilizes a calculus of variations algorithm to perform overall optimization of thrust, Isp, and thrust vector direction along a trajectory that minimizes fuel consumption for interplanetary travel. It is assumed that the propulsion system is power-limited, and thus the compromise between thrust and Isp is a variable to be optimized along the flight path. This program is capable of optimizing not only variable thrust trajectories but also constant thrust trajectories in 3-D space using a planetary ephemeris database. It is also capable of conducting planetary swing-bys. Using this program, various Earth-originating trajectories have been investigated and the optimized results have been compared to traditional CSI and high thrust trajectory solutions. Results show that VSI rocket engines reduce fuel requirements for any mission compared to CSI rocket engines. Fuel can be saved by applying swing-by maneuvers for VSI engines; but the effects of swing-bys due to VSI engines are smaller than that of CSI or high thrust engines.

Sakai, Tadashi

10

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

International Nuclear Information System (INIS)

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

2008-04-28

11

The hysteresis phenomena in a collisional magnetoplasma  

International Nuclear Information System (INIS)

[en] 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)

1981-01-01

12

Ion acoustic solitons in a warm magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

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

Ghosh, K.K.; Ray, D.

1987-11-01

13

Radiation pattern from a cold magnetoplasma antenna  

International Nuclear Information System (INIS)

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

2009-01-01

14

Specifics of impulse light-beam recrystallization of cadmium-mercury telluride layers  

International Nuclear Information System (INIS)

Changes in morphological and dislocation structures of CdxHg1-xTe(KMT) crystal surface under effect of layer impulses of various density of energy and duration are measured. Features of structure formation and change in the element composition of the near-the-surface layer of KMT crystals under nonequilibrium conditions of impulse melting and crystallization. It is shown that effect of high-power light pulses on monocrystalline samples Cd0.25Hg0.75Te leads to irreversible changes in the crystal near the surface layer, character of which depends on parameters of a laser impulse and treatment conditions. Choice of the proper conditions of laser heat radiation treatment of KMT crystals permits to form inhomogeneous structures with the assigned profile of impurity and linear defect distributions, to prepare layers with the required degree of structural development

1989-01-01

15

Enhancement of D-T reaction rate in nonuniform magnetoplasma  

International Nuclear Information System (INIS)

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

1986-01-01

16

Impedance of a large circular loop antenna in a magnetoplasma  

International Nuclear Information System (INIS)

[en] 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

1986-01-01

17

Optical parametric amplification in the magnetoplasma in semiconductors  

Science.gov (United States)

A nonlinear parametric interaction is found in the magnetoplasma in a semiconductor. The spatial asymmetry is produced by the magnetic field in the Voigt configuration, where the Lorentz force acts on the drifting electrons. The nonpolar semiconductor can be used as the nonlinear optical element. The optical parametric conversion and the second-harmonic generation are discussed. The device operates in the infrared range. The efficiencies are found to be much larger than in conventional nonlinear optical crystals.

Lida, Takashi; Mizushima, Yoshihiko

1995-01-01

18

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-12-15

19

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

20

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

 
 
 
 
21

Electromagnetic solitary structures in dense electron-positron-ion magnetoplasmas  

International Nuclear Information System (INIS)

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 ? 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.

2010-01-01

22

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

23

Electric field variability and classifications of Titan's magnetoplasma environment  

CERN Multimedia

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

24

Stochastic motion due to a single wave in a magnetoplasma  

International Nuclear Information System (INIS)

A single electrostatic wave in a magnetoplasma causes stochastic ion motion in several physically different situations. Various magnetic fields (uniform, tokamak, and mirror) and various propagation angles with respect to the field have been studied. A brief review of this work shows that all situations can be understood using the concept of overlapping resonances. Analytical calculations of the wave amplitude necessary for stochasticity have been carried out in some cases and compared with computer and laboratory experiments. In the case of an axisymmetric mirror field the calculations predict stochastic motion of ions with energy below a threshold that depends weakly on the wave amplitude and on the scale lengths of the magnetic field. Studies with an azimuthally asymmetric field show that the asymmetry causes substantial changes in the motion of some ions

1979-06-22

25

Temperature effects on the beat heating of a collisional magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

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

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

1983-01-01

26

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

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The validity of traditional categorical personality disorder diagnoses is currently re-evaluated from a continuous perspective, and the evolving DSM-V classification may describe personality disorders dimensionally. The utility of dimensional personality assessment, however, is unclear in violent offenders with severe personality pathology. Methods The temperament structure of 114 alcoholic violent offenders with antisocial personality disorder (ASPD) was compared to 84 offenders without ASPD, and 170 healthy controls. Inclusion occurred during a court-ordered mental examination preceded by homicide, assault, battery, rape or arson. Participants underwent assessment of temperament with the Tridimensional Personality Questionnaire (TPQ) and were diagnosed with DSM-III-R criteria. Results The typical temperament profile in violent offender having ASPD comprised high novelty seeking, high harm avoidance, and low reward dependence. A 21% minority scored low in trait harm avoidance. Results, including the polarized harm avoidance dimension, are in accordance with Cloninger's hypothesis of dimensional description of ASPD. The low harm avoidance offenders committed less impulsive violence than high harm avoidance offenders. High harm avoidance was associated with comorbid antisocial personality disorder and borderline personality disorder. Conclusion Results indicate that the DSM based ASPD diagnosis in alcoholic violent offenders associates with impulsiveness and high novelty seeking but comprises two different types of ASPD associated with distinct second-order traits that possibly explain differences in type of violent criminality. Low harm avoidance offenders have many traits in common with high scorers on the Hare Psychopathy Checklist-Revised (PCL-R). Results link high harm avoidance with broad personality pathology and argue for the usefulness of self-report questionnaires in clinical praxis.

Tikkanen Roope; Holi Matti; Lindberg Nina; Virkkunen Matti

2007-01-01

27

Optimal control of impulsive Volterra equations with variable impulse times  

CERN Multimedia

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

Belbas, S A

2008-01-01

28

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

International Nuclear Information System (INIS)

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

2010-05-17

29

Optimization of plasma flow parameters of the magnetoplasma compressor  

International Nuclear Information System (INIS)

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

2007-02-01

30

Nonlinear shock structure in a weakly ionised magnetoplasma  

Directory of Open Access Journals (Sweden)

Full Text Available The formation of a neutral induced weak nonlinear shock structure in a weakly ionised magnetoplasma has been analytically investigated. Using the reductive perturbation method, basic dynamical equations of a three-component (electron, ion and neutral) plasma have been reduced to a well-known Burger equation which can support a weak shock solution. Its stationary and initial value solutions have been derived to describe the characteristics of the weak shock profile. Asymptotic behaviour of the Burger solution results in a saw-tooth structure which has a practical implication to predict the nonlinear steepened structure of the nighttime irregularity in the lower portion of the Earth's ionosphere. Accordingly, it is suggested that the observation of saw-tooth shape of nighttime irregularity at 92 km could be attributed to the nonlinear saturation of the NILF mode instability as proposed by Dwivedi and Das in 1992. However, exact experimental verification of this suggestion requires more data on nighttime irregularity in the mesosphere and lower thermosphere (80-95 km) for a wide range of scale sizes extending up to about 1 km and above.

C. B. Dwivedi; S. C. Tripathy

0000-01-01

31

Amplification of an electromagnetic wave in the polariton mode of magnetoplasma  

Science.gov (United States)

The magnetoplasma amplification theory in an ionic semiconductor crystal is further expanded. A new type of a magnetoplasma amplification utilizes the phonon as an oscillator. The Lorentz force in the Voigt configuration causes the interaction between the electrons' space-charge wave, the optical phonon, and the electromagnetic wave. In the Reststrahlen frequency range, the induced dielectric constant dispersion provides a slow-wave structure and causes a phase shift in the waves, which are combined in drifting synchronization. It results in a traveling wave instability. The new amplifications appear very near the transverse phonon frequency and the longitudinal phonon frequency, respectively, corresponding to the forward-wave coupling and backward-wave coupling.

Lida, Takashi; Mizushima, Yoshihiko

1994-08-01

32

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

International Nuclear Information System (INIS)

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

2010-12-14

33

Impulsivity and Its Treatment  

Directory of Open Access Journals (Sweden)

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

P?nar Güzel Özdemir; Yavuz Selvi; Adem Ayd?n

2012-01-01

34

Risk Factors and Impulsivity in Obesity  

Directory of Open Access Journals (Sweden)

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

Bilge Burcak Annagur

2010-01-01

35

Zonal flow excitation by Shukla-Varma modes in a nonuniform dusty magnetoplasma  

International Nuclear Information System (INIS)

[en] The nonlinear coupling between the Shukla-Varma (SV) modes and the zonal flows in a nonuniform dusty magnetoplasma is considered. By using a two-fluid model and the guiding center particle drifts, a pair of coupled mode equations is obtained. The latter are Fourier analyzed to obtain a nonlinear dispersion relation, which exhibits the excitation of zonal flows by the ponderomotive force of the SV modes. The increment of the parametrically excited zonal flows is presented. The relevance of our investigation to laboratory and space plasmas is discussed

2002-01-01

36

Analytic theory for trajectories and current to a cylinder in a flowing magnetoplasma. Environmental research papers  

Energy Technology Data Exchange (ETDEWEB)

Two-dimensional guiding-center theory for a body in a flowing magnetoplasma leads to the electric potential satisfying Laplace's equation outside of the body, one or two forbidden regions, and the inner part of the wake. It is applied to a conducting cylinder larger than the shuttle, of circular cross section, with radius much less than the length, aligned with the magnetic field, which is perpendicular to the flow vector. Ion and electron trajectories and current to the cylinder are calculated. The effects of collisions, waves, and turbulence are neglected, as is the charge in the forbidden regions and wake. Because of this, the potential and trajectories of the nonimpacting particles are symmetric in the ram and wake. Therefore, the theory results in no particles hitting the wake side and no ion focusing. The steady-state potentials result in -0.26 and -0.61 V for cylinder radii of 25 and 250 m, respectively. The result of calculating the charging-time constant due to capacitance is of the order of 1 ns, which is negligible compared to the transit time. Therefore, the charging time is determined by the transit time and current to a cylinder in a flowing magnetoplasma.

Dubs, C.W.; Heinemann

1985-11-22

37

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

UK PubMed Central (United Kingdom)

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

Hamilton KR; Ansell EB; Reynolds B; Potenza MN; Sinha R

2013-01-01

38

Expanding impulsive gravitational waves  

CERN Multimedia

We explicitly demonstrate that the known solutions for expanding impulsive spherical gravitational waves that have been obtained by a "cut and paste" method may be considered to be impulsive limits of the Robinson-Trautman vacuum type N solutions. We extend these results to all the generically distinct subclasses of these solutions in Minkowski, de Sitter and anti-de Sitter backgrounds. For these we express the solutions in terms of a continuous metric. Finally, we also extend the class of spherical shock gravitational waves to include a non-zero cosmological constant.

Podolsky, J

1999-01-01

39

Relativistic impulse dynamics.  

UK PubMed Central (United Kingdom)

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

Swanson SM

2011-08-01

40

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)

1956-01-01

 
 
 
 
41

[Obsession-impulsion infanticide].  

UK PubMed Central (United Kingdom)

In 1836, the case-history of a young mother, the victim of a phobia of the impulsion to murder her infant. Esquirol considers her case as one of homocidial monomania, and classifies her among psychotic patients who have actually killed.

Gourévitch M

2006-07-01

42

[Obsession-impulsion infanticide].  

Science.gov (United States)

In 1836, the case-history of a young mother, the victim of a phobia of the impulsion to murder her infant. Esquirol considers her case as one of homocidial monomania, and classifies her among psychotic patients who have actually killed. PMID:17526415

Gourévitch, Michel

43

Nongyrotropy in magnetoplasmas: simulation of wave excitation and phase-space diffusion  

Directory of Open Access Journals (Sweden)

Full Text Available Nongyrotropic (gyrophase bunched) ion distributions in a magnetoplasma are studied by analytical methods and by two-dimensional hybrid code simulations. Nongyrotropy may not occur in a plasma being simultaneously homogeneous, stationary, and solenoidal in phase space. A detailed study is performed for a homogeneous and stationary plasma with sources and sinks in phase space. The analytical investigation cast in the framework of linearized Maxwell-Vlasov theory yields a coupling of low-frequency left-handed, right-handed, and longitudinal modes. Nongyrotropic ion distributions are unstable; they excite left-handed waves. The growth rate is comparable to that of the ion ring instability. The hybrid code simulation study confirms the expected propagation direction parallel to the background magnetic field. Three diffusion processes are studied: arc lengthening, arc broadening, and arc radius decreasing corresponding to particle energy diffusion. The characteristic diffusion time-scales are found to be of the order of 101 wave cycles.

U. Motschmann; H. Kafemann; M. Scholer

0000-01-01

44

Transverse propagation of low frequency waves in a switched magnetoplasma medium  

International Nuclear Information System (INIS)

It is known that the effect of switching a magnetoplasma medium on a travelling wave within the radio approximation (neglecting ion motion) for the case of the transverse propagation, where, electric field is normal to the direction of propagation, splits the original wave into four new extraordinary waves whose frequencies are different from the incident wave frequency (?0). However in the low frequency region ? much-lt ?be, called the hydromagnetic range, where ?be is the electron gyrofrequency, radio approximations are not valid and ion motion has to be taken into account. It can be observed from the figure that in the very low frequency range there is nearly 50% power in this wave for ?bi = 1.0. The variation of power with ?bi, the region over which the hydromagnetic approximations are valid and the failure of radio approximations within this range and other interesting results is presented.

1990-01-01

45

Shear driven electromagnetic drift-waves in a nonuniform dense magnetoplasma  

Energy Technology Data Exchange (ETDEWEB)

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

Tariq, Sabeen; Mirza, Arshad M. [Theoretical Plasma Physics Group, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Masood, Waqas [Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad 44000 (Pakistan); National Center for Physics (NCP), Islamabad 44000 (Pakistan)

2011-08-15

46

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-01-15

47

Langmuir Probe Diagnostics of the VASIMR Engine.  

Science.gov (United States)

NASA's VAriable Specific Impulse Magnetoplasma Rocket Engine (VASIMR) will provide a highly efficient propulsion source that can dramatically reduce Martian transit times, provide for more abort contingencies, and protect astronauts from space radiat...

B. C. Sinclair

2005-01-01

48

Micropower impulse radar imaging  

Energy Technology Data Exchange (ETDEWEB)

From designs developed at the Lawrence Livermore National Laboratory (LLNL) in radar and imaging technologies, there exists the potential for a variety of applications in both public and private sectors. Presently tests are being conducted for the detection of buried mines and the analysis of civil structures. These new systems use a patented ultra-wide band (impulse) radar technology known as Micropower Impulse Radar (GPR) imaging systems. LLNL has also developed signal processing software capable of producing 2-D and 3-D images of objects embedded in materials such as soil, wood and concrete. My assignment while at LLNL has focused on the testing of different radar configurations and applications, as well as assisting in the creation of computer algorithms which enable the radar to scan target areas of different geometeries.

Hall, M.S.

1995-11-01

49

An exploration of apathy and impulsivity in Parkinson disease.  

UK PubMed Central (United Kingdom)

Background. Apathy and impulsivity in Parkinson disease (PD) are associated with clinically significant behavioral disorders. Aim. To explore the phenomenology, distribution, and clinical correlates of these two behaviors. Methods. In PD participants (n = 99) without dementia we explored the distribution of measures of motivation and impulsivity using univariate methods. We then undertook factor analysis to define specific underlying dimensions of apathy and impulsivity. Regression models were developed to determine the associated demographic and clinical features of the derived dimensions. Results. The factor analysis of apathy (AES-C) revealed a two-factor solution: "cognitive-behavior" and "social indifference". The factor analysis of impulsivity (BIS-11) revealed a five-factor solution: "inattention"; "impetuosity"; "personal security"; "planning"; and "future orientation". Apathy was significantly associated with: age, age of motor symptom onset (positive correlation), disease stage, motor symptom severity, and depression. Impulsivity was significantly associated with: age of motor symptom onset (negative correlation), gambling and anxiety scores, and motor complications. We observed an overlap of apathy and impulsivity in some participants. Conclusion. In PD, apathy and impulsivity have specific phenomenological profiles and are associated with particular clinical phenotypes. In spite of this, there is some overlap of behaviors which may suggests common aspects in the pathology underlying motivation and reward processes.

Ahearn DJ; McDonald K; Barraclough M; Leroi I

2012-01-01

50

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; N. Achilleos; P. Guio

2011-01-01

51

Eruption of an arched magnetic flux rope in an ambient magnetoplasma  

Science.gov (United States)

Arched magnetic flux ropes (AMFRs) are arch-shaped, current-carrying, magnetized plasma structures that ubiquitously exist in the solar atmosphere. A laboratory plasma experiment [Tripathi and Gekelman, PRL 105, 075005 (2010)] has been built to study the eruption of AMFRs in two essential steps: (i) production of an AMFR (n˜ 10^19 m-3, Te˜14 eV, B˜1 kG, L˜0.5 m) with a persistent appearance lasting several Alfven transit times using a Lanthnum Hexaboride (LaB6) plasma source, and (ii) generation of controlled plasma flows from the foot-points of the AMFR using two laser beams (1064 nm, 1 J/pulse). An additional LaB6 source produces a large magnetoplasma in the background. The laser generated flows drive the eruption by injecting plasma and magnetic flux in the AMFR. The experiment is highly reproducible and runs continuously with a 0.5 Hz repetition rate, hence evolution of the AMFR is recorded using computer-controlled movable probes in 3D. High-speed imaging, Langmuir and 3-axis magnetic-loop probes are the main diagnostic tools. New results from this experiment on global kink-mode oscillations of the AMFR, excitation of fast waves, and ejection of a large magnetic flux rope from the apex of the AMFR will be presented.

Tripathi, Shreekrishna; Gekelman, Walter

2012-10-01

52

Electric and thermodynamic properties of plasma flows created by a magnetoplasma compressor  

International Nuclear Information System (INIS)

A magnetoplasma compressor of compact geometry (MPC-CG) with a semi-transparent electrode system that operates in the ion current transfer regime was constructed and studied. The electric and thermodynamic parameters of the discharge and the plasma flow created in different gases and their mixtures (hydrogen, nitrogen, argon and Ar + 3% H2) have been measured to optimize the working conditions within the 100-3000 Pa pressure range for input energy up to 6.4 kJ. A special construction of the accelerator electrode system shielded by the self-magnetic field results in protection from erosion, which is the main cause of the high current cut-off in conventional plasma accelerators. It was found that the compression plasma flow velocity, electron density and temperature predominantly depend on the energy conversion rate from the energy supply to the plasma, since the current cut-off is avoided. The maximum energy conversion rate for MPC-CG was found when operating in hydrogen. The plasma flow velocity and electron density maximum values are measured close to 100 km s-1 and 1017 cm-3, respectively, for input energy of 6.4 kJ at 1000 Pa pressure in hydrogen. Our results appear in good agreement with existing theoretical and experimental data.

2004-02-01

53

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

International Nuclear Information System (INIS)

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

2004-01-01

54

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

International Nuclear Information System (INIS)

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

2008-01-01

55

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1993-01-10

56

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

International Nuclear Information System (INIS)

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

1993-01-01

57

Impulsivity: A deficiency of inhibitory control?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Impulsivity has been defined as acting without thinking. Impulsivity can be quantified by impulsivity questionnaires, but also by behavioral paradigms which tax inhibitory control. Previous research has repeatedly demonstrated deficient inhibitory control in psychopathological samples characterized ...

Lansbergen, M.M.

58

Teaching about Impulse and Momentum  

Science.gov (United States)

This American Association of Physics Teachers/Physics Teaching Resource Agents (APPT/PTRA) spiral-bound manual features labs and demos physics teachers can use to give students hands-on opportunities to learn about impulse and momentum. "Make-and-take activities" include AAPT Apparatus Contest winners "An Air Impulse Rocket," "A Fan Driven…

Franklin, Bill

2004-01-01

59

Impulsivity and rapid decision-making for reward.  

UK PubMed Central (United Kingdom)

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

Burnett Heyes S; Adam RJ; Urner M; van der Leer L; Bahrami B; Bays PM; Husain M

2012-01-01

60

Experimental investigation of the effectiveness of the matching of a magnetoplasma compressor with an explosive magnetohydrodynamic generator  

Energy Technology Data Exchange (ETDEWEB)

The results of an experimental investigation of the matching of an explosive MHD generator with an actively inductive plasma load--a high-current discharge of an magnetoplasma compressor-are presented. The efficiency of the conversion of the chemical energy of the explosive into the light energy of the discharge was eta/sub rad/approx. = 0.3% and constituted 12--15 J of the radiation energy with 1 g of explosive charge. The possibility of using explosive MHD generators as very efficient (eta/sub rad/> or approx. =1%) sources of electrical power in experiments with high-current radiating discharges is demonstrated.

Kamrukov, A.S.; Kashnikov, G.N.; Kozlov, N.P.; Kondratenko, M.M.; Lebedev, E.F.; Orlov, V.K.; Ostashev, V.E.; Protasov, Y.S.; Semenov, A.M.

1984-03-01

 
 
 
 
61

Qualifying an impulse digitizer for measurements in HV impulse tests  

Energy Technology Data Exchange (ETDEWEB)

Working groups are presently engaged in preparing a standard on digital recorders for measurement in HV impulse tests. This paper shows how the main tests described in the proposed standard can be applied towards qualifying an impulse digitizer for HV Impulse measurements. Experimental results from the application of these techniques to different digitizers are presented. A major problem in using digital recorders in HV laboratories is electromagnetic interference. Previous low frequency measurements have indicated that high frequencies can be a problem and this paper reports some measurements at high frequencies. The consequences of these measurements for electromagnetic compatibility are discussed.

McComb, T.R. (National Research Council of Canada, Ottawa, Ontario (CA)); Kuffel, J. (Ontario Hydro, Toronto, ON (Canada). Research Div.); Malewski, R. (Institut de Recherche d' Hydro-Quebec, Varennes, PQ (Canada)); Schon, K. (Physikalisch-Technische Bundesanstalt, Braunschweig (Germany, F.R.))

1990-07-01

62

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

Directory of Open Access Journals (Sweden)

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

Donatella Marazziti; Stefano Baroni; Irene Masala; et al

2009-01-01

63

"Impulsivity": relations between self-report and behavior.  

UK PubMed Central (United Kingdom)

The trait of "impulsivity" is difficult to place within a personality framework due to the many potential pathways to impulsive behavior and the lack of consensus regarding the structure of the trait(s). This lack of consensus also hinders systematic investigation into relations between "impulsivity" and its behavioral manifestations. Undergraduates (Sample 1 N = 507) completed a battery of self-report measures, all purporting to assess trait "impulsivity"; a subset (n = 408) and Sample 2 (N = 388) also completed a retrospective questionnaire about specific behaviors they may have engaged in over the past year, and another subset of Sample 1 agreed to complete (n = 208) and actually completed (n = 152) a 2-week prospective measure of impulsive behaviors. Finally, a subset of Sample 1 (n = 321) and Sample 2 completed an omnibus self-report inventory in a follow-up study. Structural equation modeling confirmed a 3-factor structure of what we call impulsigenic traits-traits that are manifested in impulsive behavior. This finding is consistent with previous research and supports the growing consensus that "impulsivity" is a colloquial label attached to a group of distinct traits that have phenotypically similar behavioral manifestations. Each of these impulsigenic traits relates differentially to impulsive behavior and to broad temperamental dimensions. The results also show clear 2-factor structures of both daily and less frequent (yearly/semiyearly) impulsive behaviors. Finally, a unique method of data collection permitted an investigation of relations between the impulsigenic and other personality traits and observed behaviors, demonstrating the predictive utility of personality traits to discrete, in situ behaviors.

Sharma L; Kohl K; Morgan TA; Clark LA

2013-03-01

64

Impulsive rats are less maternal.  

UK PubMed Central (United Kingdom)

Early life environment and maternal care can have long-lasting effects on behavior and physiology. Previously, we found that compared to mother-reared (MR) female rats, rats reared without mothers, siblings, and nest, through artificially rearing (AR), show reduced levels of maternal behavior when they grow up. These effects can be reversed if AR pups are provided with extra "licking-like" tactile stimulation during the preweaning period [Gonzalez et al. [2001] Developmental Psychobiology, 38(1), 11-42]. We also found that AR rats are more action impulsive and have reduced attentional capacities in comparison to their MR siblings [Lovic, Fletcher, & Fleming, in preparation; Lovic & Fleming [2004] Behavioural Brain Research 148: 209-219]. However, it is unknown whether increased impulsivity contributes to reduced levels of maternal behaviors. The purpose of this study was to assess the relationship between impulsivity and maternal behavior in AR and MR rats. Female rats were reared with (MR) or without mothers (AR) and half of the AR rats received additional stroking stimulation. As adults, AR and MR rats were mated and maternal behavior towards their own pups was assessed. In addition, rats were assessed on impulsive action (differential reinforcement of low-rate schedule; DRL-20s). Consistent with previous findings, AR rats were both less maternal and more action impulsive than MR rats. Partial correlations revealed that impulsivity was inversely related to pup licking-impulsive rats were less maternal.

Lovic V; Palombo DJ; Fleming AS

2011-01-01

65

Impulse Generation Mechanism in Glycerin Propellant Laser Thruster  

International Nuclear Information System (INIS)

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

2004-03-30

66

High-intensity drying processes: Impulse drying. Annual report  

Energy Technology Data Exchange (ETDEWEB)

Experiments were conducted on a sheet-fed pilot-scale shoe press to compare impulse drying and double-felted pressing. Both an IPST (Institute of Paper Science and Technology) ceramic coated and Beloit Type A press roll were evaluated for lienrboard sheet structures having a wide range of z-direction permeability. Purpose was to find ways of correcting sheet sticking problems observed in previous pilot-scale shoe press experiments. Results showed that impulse drying was superior to double felted pressing in both press dryness and in important paper physical properties. Impulse drying critical temperature was found to depend on specific surface of the heated layer of the sheet, thermal properties of the press roll surface, and choice of felt. Impulse drying of recycled and two-ply liner was demonstrated for both Southern Pile and Douglas fir-containing furnishes.

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

1993-12-01

67

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

UK PubMed Central (United Kingdom)

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

Felthous AR; Lake SL; Rundle BK; Stanford MS

2013-05-01

68

Non-linear diffusion of charged particles in a turbulent magnetoplasma  

International Nuclear Information System (INIS)

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

1985-01-01

69

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

Science.gov (United States)

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

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

70

Resonant Impulsive Stimulated Raman Scattering  

International Nuclear Information System (INIS)

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

1988-01-01

71

Resonant Impulsive Stimulated Raman Scattering  

Energy Technology Data Exchange (ETDEWEB)

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

Mokhtari, A.; Chesnoy, J.

1988-03-15

72

Criteria for impulsive rock fracture  

International Nuclear Information System (INIS)

Explosive or percussive breakage of rock relies on impulsive rock fracture and both the fracture stress and fracture energy under such conditions are observed to be significantly greater than measured quasi-statically. The implication of rate dependence has been verified in recent tensile fracture studies and in the present report this data has been compiled, significant trends noted, and comparisons made with earlier impulsive fracture criteria

1980-01-01

73

Pre-attentive information processing and impulsivity in bipolar disorder.  

Science.gov (United States)

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

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

2013-09-03

74

Weakly nonlinear analysis of impulsively-forced Faraday waves.  

UK PubMed Central (United Kingdom)

Parametrically-excited surface waves, forced by a repeating sequence of delta-function impulses, are considered within the framework of the Zhang-Viñals model [W. Zhang and J. Viñals, J. Fluid Mech. 336, 301 (1997)]. With impulsive forcing, the linear stability analysis can be carried out exactly and leads to an implicit equation for the neutral stability curves. As noted previously [J. Bechhoefer and B. Johnson, Am. J. Phys. 64, 1482 (1996)], in the simplest case of N=2 equally-spaced impulses per period (which alternate up and down) there are only subharmonic modes of instability. The familiar situation of alternating subharmonic and harmonic resonance tongues emerges only if an asymmetry in the spacing between the impulses is introduced. We extend the linear analysis for N=2 impulses per period to the weakly nonlinear regime, where we determine the leading order nonlinear saturation of one-dimensional standing waves as a function of forcing strength. Specifically, an analytic expression for the cubic Landau coefficient in the bifurcation equation is derived as a function of the dimensionless spacing between the two impulses and the fluid parameters that appear in the Zhang-Viñals model. As the capillary parameter is varied, one finds a parameter regime of wave amplitude suppression, which is due to a familiar 1:2 spatiotemporal resonance between the subharmonic mode of instability and a damped harmonic mode. This resonance occurs for impulsive forcing even when harmonic resonance tongues are absent from the neutral stability curves. The strength of this resonance feature can be tuned by varying the spacing between the impulses. This finding is interpreted in terms of a recent symmetry-based analysis of multifrequency forced Faraday waves [J. Porter, C. M. Topaz, and M. Silber, Phys. Lett. 93, 034502 (2004); C. M. Topaz, J. Porter, and M. Silber, Phys. Rev. E 70, 066206 (2004)].

Catllá A; Porter J; Silber M

2005-11-01

75

Weakly nonlinear analysis of impulsively-forced Faraday waves  

Science.gov (United States)

Parametrically-excited surface waves, forced by a repeating sequence of N delta-function impulses, are considered within the framework of the Zhang-Viñals model [W. Zhang and J. Viñals, J. Fluid Mech. 336, 301 (1997)]. With impulsive forcing, the linear stability analysis can be carried out exactly and leads to an implicit equation for the neutral stability curves. As noted previously [J. Bechhoefer and B. Johnson, Am. J. Phys. 64, 1482 (1996)], in the simplest case of N=2 equally-spaced impulses per period (which alternate up and down) there are only subharmonic modes of instability. The familiar situation of alternating subharmonic and harmonic resonance tongues emerges only if an asymmetry in the spacing between the impulses is introduced. We extend the linear analysis for N=2 impulses per period to the weakly nonlinear regime, where we determine the leading order nonlinear saturation of one-dimensional standing waves as a function of forcing strength. Specifically, an analytic expression for the cubic Landau coefficient in the bifurcation equation is derived as a function of the dimensionless spacing between the two impulses and the fluid parameters that appear in the Zhang-Viñals model. As the capillary parameter is varied, one finds a parameter regime of wave amplitude suppression, which is due to a familiar 1:2 spatiotemporal resonance between the subharmonic mode of instability and a damped harmonic mode. This resonance occurs for impulsive forcing even when harmonic resonance tongues are absent from the neutral stability curves. The strength of this resonance feature can be tuned by varying the spacing between the impulses. This finding is interpreted in terms of a recent symmetry-based analysis of multifrequency forced Faraday waves [J. Porter, C. M. Topaz, and M. Silber, Phys. Lett. 93, 034502 (2004); C. M. Topaz, J. Porter, and M. Silber, Phys. Rev. E 70, 066206 (2004)].

Catllá, Anne; Porter, Jeff; Silber, Mary

2005-11-01

76

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

UK PubMed Central (United Kingdom)

The control of impulse behavior is a multidimensional concept subdivided into separate subcomponents, which are thought to represent different underlying mechanisms due to either disinhibitory processes or poor decision-making. In patients with Parkinson's disease (PD), dopamine-agonist (DA) therapy has been associated with increased impulsive behavior. However, the relationship among these different components in the disease and the role of DA is not well understood. In this imaging study, we investigated in PD patients the effects of DA medication on patterns of brain activation during tasks testing impulsive choices and actions. Following overnight withdrawal of antiparkinsonian medication, PD patients were studied with a H2 ((15)) O PET before and after administration of DA (1?mg of pramipexole), while they were performing the delay discounting task (DDT) and the GoNoGo Task (GNG). We observed that pramipexole augmented impulsivity during DDT, depending on reward magnitude and activated the medial prefrontal cortex and posterior cingulate cortex and deactivated ventral striatum. In contrast, the effect of pramipexole during the GNG task was not significant on behavioral performance and involved different areas (i.e., lateral prefrontal cortex). A voxel-based correlation analysis revealed a significant negative correlation between the discounting value (k) and the activation of medial prefrontal cortex and posterior cingulate suggesting that more impulsive patients had less activation in those cortical areas. Here we report how these different subcomponents of inhibition/impulsivity are differentially sensitive to DA treatment with pramipexole influencing mainly the neural network underlying impulsive choices but not impulsive action. Hum Brain Mapp, 2013. © 2013 Wiley Periodicals, Inc.

Antonelli F; Ko JH; Miyasaki J; Lang AE; Houle S; Valzania F; Ray NJ; Strafella AP

2013-09-01

77

Impulsivity in the supermarket. Responses to calorie taxes and subsidies in healthy weight undergraduates.  

UK PubMed Central (United Kingdom)

The present study investigated the effect of taxing high-energy dense products and subsidizing low-energy dense products on changes in calorie consumption. More specifically, we hypothesized that 'more impulsive' individuals were less influenced by such pricing strategies compared to 'less impulsive' individuals. Contrary to our hypothesis, results showed that 'more impulsive' individuals adjusted their calorie consumption with regard to price changes whereas 'less impulsive' participants were less influenced by price changes. Furthermore, taxing high-energy dense products was more successful in reducing calorie consumption than subsidizing low-energy dense products.

Giesen JC; Havermans RC; Nederkoorn C; Jansen A

2012-02-01

78

The impact of self-reported life stress on current impulsivity in cocaine dependent adults.  

Science.gov (United States)

Current cocaine treatments may be enhanced with a better understanding of the underlying mechanisms that contribute to the onset and maintenance of the disease, such as life stress and impulsivity. Life stress and impulsivity have previously been studied independently as contributors to drug use, and the current study expands upon past research by examining how these factors interact with one another. The aim of the current study was to evaluate the role of life stress in predicting impulsivity in a non-treatment seeking cocaine-dependent sample (N=112). Analyses revealed that trait impulsivity (as measured by the Barratt Impulsiveness Scale) was associated with education (r=-3.09, p2.21, p=0.03). Overall exposure to life stress was not significantly correlated to either aspect of impulsivity. However several specific life stressors were significantly related to greater impulsivity including having been put up for adoption or in foster care (t=-2.96, p<0.01), and having a child taken away against their will (t=-2.68, p=0.01). These findings suggest that age and education relate to impulsivity; and that while an overall compilation of life stress scores was not related to impulsivity, specific types of stress related to either being taken away from a parent or having a child taken away were. Future studies should assess these constructs longitudinally to restrict response bias. PMID:23796525

Ross, Elizabeth L; Yoon, Jin H; Mahoney, James J; Omar, Yasmine; Newton, Thomas F; De La Garza, Richard

2013-06-21

79

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

International Nuclear Information System (INIS)

[en] 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.

2010-01-01

80

Brain circuitry of compulsivity and impulsivity.  

UK PubMed Central (United Kingdom)

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.

Grant JE; Kim SW

2013-05-01

 
 
 
 
81

Measurements of laser generated impulse  

Energy Technology Data Exchange (ETDEWEB)

The total impulse delivered by pulsed-laser illumination of planar targets in vacuum. Data are presented for several target materials (aluminum and some of its alloys, titanium, and kevlar/epoxy structural composite) as a function of incident fluence for laser wavelengths of 248 nm, 2.8 ..mu..m, and 10.6 ..mu..m. 4 tabs.

King, T.; Barrus, D.; Dingus, R.; Osborne, Z.; Phipps, C.

1986-01-01

82

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

UK PubMed Central (United Kingdom)

Impulsive choice, a form of impulsivity, is associated with tobacco smoking in humans. Trait impulsivity may be a vulnerability factor for smoking, or smoking may lead to impulsive behaviors. We investigated the effects of 14-day nicotine exposure (6.32mg/kg/day base, subcutaneous minipumps) and spontaneous nicotine withdrawal on impulsive choice in low impulsive (LI) and high impulsive (HI) rats. Impulsive choice was measured in the delayed reward task in which rats choose between a small immediate reward and a large delayed reward. HI and LI rats were selected from the highest and lowest quartiles of the group before exposure to nicotine. In non-selected rats, nicotine or nicotine withdrawal had no effect on impulsive choice. In LI rats, chronic nicotine exposure decreased preference for the large reward with larger effects at longer delays indicating increased impulsive choice. Impulsive choices for the smaller immediate rewards continued to be increased during nicotine withdrawal in LI rats. In HI rats, nicotine exposure and nicotine withdrawal had no effect on impulsive choice, although there was a tendency for decreased preference for the large reward at short delays. These results indicate that nicotine- and nicotine withdrawal-induced increases in impulsive choice depend on trait impulsivity with more pronounced increases in impulsive choice in LI compared to HI subjects. Increased impulsivity during nicotine exposure may strengthen the addictive properties of nicotine and contribute to compulsive nicotine use.

Kayir H; Semenova S; Markou A

2013-09-01

83

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

84

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

International Nuclear Information System (INIS)

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

1983-01-01

85

Plasma properties in high power impulse magnetron sputtering  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The work presented in this thesis involves experimental and theoretical studies related to plasma properties in high power impulse magnetron sputtering (HiPIMS), and more specifically plasma transport. HiPIMS is an ionized PVD method based on conventional direct current magnetron sputtering (dcMS). ...

Lundin, Daniel

86

Neuroanatomical and Neurochemical Basis of Impulsivity  

Directory of Open Access Journals (Sweden)

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

Kemal Yazici; Aylin Ertekin Yazici

2010-01-01

87

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

2008-01-01

88

Impulse-based methods for fluid flow  

Energy Technology Data Exchange (ETDEWEB)

A Lagrangian numerical method based on impulse variables is analyzed. A relation between impulse vectors and vortex dipoles with a prescribed dipole moment is presented. This relation is used to adapt the high-accuracy cutoff functions of vortex methods for use in impulse-based methods. A source of error in the long-time implementation of the impulse method is explained and two techniques for avoiding this error are presented. An application of impulse methods to the motion of a fluid surrounded by an elastic membrane is presented.

Cortez, R.

1995-05-01

89

Laser impulse coupling at 130 fs  

Energy Technology Data Exchange (ETDEWEB)

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

Phipps, C. [Photonic Associates, 200A Ojo de la Vaca Road, Santa Fe, NM 87508 (United States)]. E-mail: crphipps@aol.com; Luke, J. [Photonic Associates, 200A Ojo de la Vaca Road, Santa Fe, NM 87508 (United States); NMT Institute for Engineering Research and Applications, 901 University Blvd. SE, Albuquerque, NM 87106-4339 (United States); Funk, D. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Moore, D. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Glownia, J. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Lippert, T. [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

2006-04-30

90

Laser impulse coupling at 130 fs  

International Nuclear Information System (INIS)

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

2006-04-30

91

Emotion regulation and impulsivity in young adults  

DEFF Research Database (Denmark)

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

Schreiber, Liana R N; Grant, Jon E

2012-01-01

92

Pipeline integrity monitoring using system impulse response  

Energy Technology Data Exchange (ETDEWEB)

The impulse response function of a system can be used to predict, detect, and diagnose abnormality in the system. The impulse response function can be extracted indirectly using cross-correlations between a low amplitude pseudo-random binary disturbance and the system`s output. This method is applied to pipeline hydraulics as a means of integrity monitoring. The ability of the method to extract a pipeline`s impulse response function with the presence of data noise is demonstrated. Characteristic changes in the impulse response function as a result of a leak or a dent are identified. Examples show that the impulse response function can be used to detect and locate a leak. However, the impulse response is not sensitive to detect small to moderate-sized dents. The procedure of extracting the pipeline`s impulse response function by cross-correlations is noise-tolerant and can be conducted in the background without interfering pipeline operations.

Liou, J.C.P. [Univ. of Idaho, Moscow, ID (United States). Dept. of Civil Engineering

1996-12-31

93

Activity and impulsive action are controlled by different genetic and environmental factors.  

UK PubMed Central (United Kingdom)

Both impulsivity in operant tasks and locomotor activity in a novel open field are known to predict the development of addiction-related behavior in rodents. In this study, we investigated to what extent impulsivity in the five-choice serial reaction time task and various measures of novelty exploration are controlled by shared genetic and environmental factors in 12 different inbred mouse strains. No genetic correlation was observed between the level of impulsivity and levels of activity, a low correlation was observed with traditional measures of anxiety-like behavior (impulsive strains tend to be less anxious) and a highly significant correlation was found between impulsivity and specific aspects of movement. Furthermore, we found that impulsivity and all measures of novelty exploration were under control of different environmental factors. Interestingly, in the dorsal medial prefrontal cortex, a brain region involved in impulsivity and activity in novelty exploration tests; these behavioral measures correlated with the expression of different genes (respectively, Frzb, Snx5, BC056474 and the previously identified Glo1). Taken together, our study shows that impulsivity and activity in novelty exploration tests are genetically and environmentally distinct, suggesting that mouse models of these behaviors provide complementary insights into the development of substance abuse disorder.

Loos M; van der Sluis S; Bochdanovits Z; van Zutphen IJ; Pattij T; Stiedl O; Smit AB; Spijker S

2009-11-01

94

A profile approach to impulsivity in bipolar disorder: the key role of strong emotions.  

UK PubMed Central (United Kingdom)

OBJECTIVE: Bipolar disorder has been associated with elevated impulsivity - a complex construct subsuming multiple facets. We aimed to compare specific facets of impulsivity in bipolar disorder, including those related to key psychological correlates of the illness: reward sensitivity and strong emotion. METHOD: Ninety-one individuals diagnosed with bipolar I disorder (inter-episode period) and 80 controls completed several well-validated impulsivity measures, including those relevant to reward (Fun-seeking subscale of the Behavioral Activation System scale) and emotion (Positive Urgency and Negative Urgency scales). RESULTS: Bipolar participants reported higher impulsivity scores than did controls on all of the impulsivity measures, except the Fun-seeking subscale of the Behavioral Activation System scale. Positive Urgency - a measure assessing the tendency to act impulsively when experiencing strong positive emotion - yielded the largest group differences: F(1,170) = 78.69, P < 0.001, partial ?(2)  = 0.316. Positive Urgency was also associated with poorer psychosocial functioning in the bipolar group: ?R(2)  = 0.24, b = -0.45, P < 0.001. CONCLUSION: Individuals with bipolar I disorder appear to be at particular risk of behaving impulsively when experiencing strong positive emotions. Findings provide an important first step toward developing a more refined understanding of impulsivity in bipolar disorder with the potential to inform targeted interventions.

Muhtadie L; Johnson SL; Carver CS; Gotlib IH; Ketter TA

2013-04-01

95

Impulsivity and the modular organization of resting-state neural networks.  

UK PubMed Central (United Kingdom)

Impulsivity is a complex trait associated with a range of maladaptive behaviors, including many forms of psychopathology. Previous research has implicated multiple neural circuits and neurotransmitter systems in impulsive behavior, but the relationship between impulsivity and organization of whole-brain networks has not yet been explored. Using graph theory analyses, we characterized the relationship between impulsivity and the functional segregation ("modularity") of the whole-brain network architecture derived from resting-state functional magnetic resonance imaging (fMRI) data. These analyses revealed remarkable differences in network organization across the impulsivity spectrum. Specifically, in highly impulsive individuals, regulatory structures including medial and lateral regions of the prefrontal cortex were isolated from subcortical structures associated with appetitive drive, whereas these brain areas clustered together within the same module in less impulsive individuals. Further exploration of the modular organization of whole-brain networks revealed novel shifts in the functional connectivity between visual, sensorimotor, cortical, and subcortical structures across the impulsivity spectrum. The current findings highlight the utility of graph theory analyses of resting-state fMRI data in furthering our understanding of the neurobiological architecture of complex behaviors.

Davis FC; Knodt AR; Sporns O; Lahey BB; Zald DH; Brigidi BD; Hariri AR

2013-06-01

96

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

Directory of Open Access Journals (Sweden)

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

Donald M. Dougherty; Dawn M. Richard; Lisa M. James; Charles W. Mathias

2010-01-01

97

Impulsivity, self-control, and hypnotic suggestibility.  

UK PubMed Central (United Kingdom)

Hypnotic responding might be due to attenuated frontal lobe functioning after the hypnotic induction. Little is known about whether personality traits linked with frontal functioning are associated with responsiveness to hypnotic suggestions. We assessed whether hypnotic suggestibility is related to the traits of self-control and impulsivity in 154 participants who completed the Brief Self-Control Scale, the Self-Regulation Scale, the Barratt Impulsiveness Scale (BIS-11), and the Harvard Group Scale of Hypnotic Susceptibility (HGSHS:A). BIS-11 non-planning impulsivity correlated positively with HGSHS:A (Bonferroni-corrected). Furthermore, in the best model emerging from a stepwise multiple regression, both non-planning impulsivity and self-control positively predicted hypnotic suggestibility, and there was an interaction of BIS-11 motor impulsivity with gender. For men only, motor impulsivity tended to predict hypnotic suggestibility. Hypnotic suggestibility is associated with personality traits linked with frontal functioning, and hypnotic responding in men and women might differ.

Ludwig VU; Stelzel C; Krutiak H; Prunkl CE; Steimke R; Paschke LM; Kathmann N; Walter H

2013-06-01

98

Impulsivity and sexual assault in college men.  

UK PubMed Central (United Kingdom)

Although impulsivity has been consistently linked to perpetration of sexual aggression, results lack clarity because they do not account for the substantial heterogeneity associated with the construct. The UPPS-P model (Lynam, Smith, Whiteside, & Cyders, 2006), which was proposed to clarify the multidimensional nature of impulsivity, has yet to be applied to sexual aggression. We measured UPPS-P Impulsivity in a sample of male college students who also self-reported on perpetration of sexual aggression. As predicted, impulsivity distinguished perpetrators from nonperpetrators. Perpetrators scored higher than non-perpetrators on Negative Urgency, Positive Urgency, and lack of Premeditation. Results suggest that the impulsivity traits most relevant to sexual aggression are the tendency to act impulsively when experiencing intense emotions (Positive and Negative Urgency) and lack of forethought and planning (lack of Premeditation).

Mouilso ER; Calhoun KS; Rosenbloom TG

2013-01-01

99

Impulsivity and sexual assault in college men.  

Science.gov (United States)

Although impulsivity has been consistently linked to perpetration of sexual aggression, results lack clarity because they do not account for the substantial heterogeneity associated with the construct. The UPPS-P model (Lynam, Smith, Whiteside, & Cyders, 2006), which was proposed to clarify the multidimensional nature of impulsivity, has yet to be applied to sexual aggression. We measured UPPS-P Impulsivity in a sample of male college students who also self-reported on perpetration of sexual aggression. As predicted, impulsivity distinguished perpetrators from nonperpetrators. Perpetrators scored higher than non-perpetrators on Negative Urgency, Positive Urgency, and lack of Premeditation. Results suggest that the impulsivity traits most relevant to sexual aggression are the tendency to act impulsively when experiencing intense emotions (Positive and Negative Urgency) and lack of forethought and planning (lack of Premeditation). PMID:23862308

Mouilso, Emily R; Calhoun, Karen S; Rosenbloom, Thomas G

2013-01-01

100

Impulsive differential inclusions a fixed point approach  

CERN Multimedia

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

 
 
 
 
101

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

102

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

Directory of Open Access Journals (Sweden)

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

S.Janaki; Dr. Siva Yellampalli,

2013-01-01

103

Prueba de impulso cefálico/ Head impulse test  

Scientific Electronic Library Online (English)

Full Text Available 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 cont (more) ribuir 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 m (more) ethod: 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.

Breinbauer K, Hayo A; Anabalón B, José Luis

2011-08-01

104

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

International Nuclear Information System (INIS)

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

2007-01-01

105

Impulse in a Double Ball Bounce  

Directory of Open Access Journals (Sweden)

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

Daniel Y. Nielsen

2010-01-01

106

Simplified calculation of detonation induced impulse  

International Nuclear Information System (INIS)

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

1981-01-01

107

The effects of impulse noise on hearing.  

Science.gov (United States)

Impulse noise is a peculiar type of noise that retains its separate status, both as a physical phenomenon and as an adverse influence exerted upon human recipients. The ongoing research and numerous experiments with animals and industrial populations have not yet fully explained its nature. There are no clear-cut standards of measurement procedures, an impulse evaluation, and no admissible intensity levels. A comprehensive review of both Polish and foreign literature on this subject shows that the following features have the most traumatizing effect on the hearing organs: peak value, impulse duration rate, spectrum composition, repetition frequency, equivalent energy level, and a total number of impulses. PMID:2130867

Pawlas, K; Grzesik, J; Witula, R

1990-01-01

108

The effects of impulse noise on hearing.  

UK PubMed Central (United Kingdom)

Impulse noise is a peculiar type of noise that retains its separate status, both as a physical phenomenon and as an adverse influence exerted upon human recipients. The ongoing research and numerous experiments with animals and industrial populations have not yet fully explained its nature. There are no clear-cut standards of measurement procedures, an impulse evaluation, and no admissible intensity levels. A comprehensive review of both Polish and foreign literature on this subject shows that the following features have the most traumatizing effect on the hearing organs: peak value, impulse duration rate, spectrum composition, repetition frequency, equivalent energy level, and a total number of impulses.

Pawlas K; Grzesik J; Witula R

1990-01-01

109

Impulsivity moderates the association between racial discrimination and alcohol problems.  

UK PubMed Central (United Kingdom)

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

Latzman RD; Chan WY; Shishido Y

2013-08-01

110

Impulsivity moderates the association between racial discrimination and alcohol problems.  

Science.gov (United States)

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

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

2013-08-28

111

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

UK PubMed Central (United Kingdom)

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

Weygandt M; Mai K; Dommes E; Leupelt V; Hackmack K; Kahnt T; Rothemund Y; Spranger J; Haynes JD

2013-07-01

112

The uncompetitive NMDA receptor antagonists ketamine and memantine preferentially increase the choice for a small, immediate reward in low-impulsive rats.  

UK PubMed Central (United Kingdom)

RATIONALE: Impulsive behavior is categorically differentiated between impulsive action, the inability to withhold from acting out a response, and impulsive choice, the greater preference for an immediate and smaller reward over a delayed but more advantageous reward. While the effects of N-methyl-D-aspartic acid (NMDA) receptor antagonists on impulsive action have been extensively characterized, there are very few and conflicting reports on the effects of this class of drugs on impulsive choice. OBJECTIVES: Using a modified adjusting delay task, we investigated the effects of uncompetitive and competitive blockade of NMDA receptors on impulsive choice. METHODS: Male Wistar rats were trained in a modified adjusting delay task, which involved repeated choice between a low reinforcing solution delivered immediately and a highly reinforcing solution delivered after a variable delay. Rats were then administered either the NMDA receptor uncompetitive antagonists ketamine or memantine, or the competitive antagonists D-AP-5 or CGS 19755. RESULTS: Ketamine treatment dose-dependently increased impulsive choice, and this effect was selective for low-impulsive but not high-impulsive rats. Similarly, memantine treatment dose-dependently increased impulsive choice with a preferential effect for low-impulsive rats. While D-AP-5 treatment did not affect impulsive choice, CGS 19755 increased impulsivity, however, at the same doses at which it caused a marked response inhibition. CONCLUSIONS: NMDA receptor uncompetitive, but not competitive, antagonists significantly increased impulsive choice, preferentially in low-impulsive rats. These findings demonstrate that the effects of NMDA receptor blockade on impulsive choice are not generalizable and depend on the specific mechanism of action of the antagonist used.

Cottone P; Iemolo A; Narayan AR; Kwak J; Momaney D; Sabino V

2013-03-01

113

Structural Analysis of Portfolio Risk Using Beta Impulse Response Functions  

UK PubMed Central (United Kingdom)

We estimate the data generating process of daily excess returns of 20 major Germanstocks in a CAPM framework with time varying betas. Our sample spans a 23year period from 1974 to 1996. An asymmetric dependence of volatility on laggedinnovations is taken into account. We introduce beta impulse response functions toshed light on the structural implications of systematic risk associated with competingvolatility models. The dependence of beta on news is characterized with respectto different sources (asset specific vs. market general news). The empirical resultssuggest that negative news emerging from the market involve a stronger impact onbeta relative to positive news. Concerning firm specific news the opposite relationis found for the majority of the analysed data sets.Keywords: Multivariate GARCH--Models, asymmetry, impulse response analysis,CAPMInstitut fur Statistik und Okonometrie and Sonderforschungsbereich 373, WirtschaftswissenschaftlicheFakultat, Humboldt--Unive...

Christian M. Hafner; Helmut Herwartz

114

A new Calculation Procedure for Spatial Impulse Responses in Ultrasound  

UK PubMed Central (United Kingdom)

A new procedure for the calculation of spatial impulse responses for linear sound fieldsis introduced. This calculation procedure uses the well known technique of calculatingthe spatial impulse response from the intersection of a circle emanating from the projectedspherical wave with the boundary of the emitting aperture. This general result holds forall aperture boundaries for a flat transducer surface, and this is used in the procedure toyield the response for all types of flat transducers. An arbitrary apodization function overthe aperture can be incorporated through a simple one-dimensional integration. The caseof a soft baffle mounting of the aperture is also included. Specific solutions for transducerboundaries made from lines are given, so that any polygon transducer can be handled.Specific solutions for circles are also given. Finally, a solution for a general boundary isstated, and all these boundary elements can be combined to, e.g., handle annular arrays...

Jrgen Arendt Jensen Jasa; Jrgen Arendt Jensen

115

Oscillation criteria for impulsive dynamic equations on time scales  

Directory of Open Access Journals (Sweden)

Full Text Available Oscillation criteria for impulsive dynamic equations on time scales are obtained via impulsive inequality. An example is given to show that the impulses play a dominant part in the oscillations of dynamic equations on time scales.

Mugen Huang; Weizhen Feng

2007-01-01

116

Laser impulse generation required for space debris deorbiting  

Science.gov (United States)

Impulse generation using laser energy has advantages for aerospace propulsion; energy can be supplied from a remote device, thereby reducing a necessary mass on board and accompanied cost; the specific input energy is not limited by inherent energy of working fluid. After Kantrowitz proposed the concept of laser propulsion in 1972, impulse generation and launch performance either with single or multiple laser pulses has been experimentally studied. Possible application of this technique ranges even to space debris de-orbiting. As the example which actually launched a projectile, Yabe conducted an experiment that 0.1-gram paper airplane with an acryl overlay was launched at about 1.4 m/s using 0.6-J-class Nd:YAG laser. In Tanaka et al.'s experiment, 7 -microgram multi-layered flyer was accelerated to about 13 km/s using 20-J-class Nd:glass laser. Myrabo, using a 10-kW-class repetitive-pulse carbon dioxide laser, successfully launched a 51-gram 'lightcraft' at about 15 m/s up to altitude of 71 m. In these experiments, the values of impulse (i.e., momentum) and momentum coupling coefficient were estimated about 0.14 x 10-3 kg-m/s, 91x10-3 kg-m/s and 765x10-3 kg-m/s and about 240 N/MW, 4 N/MW and 50 N/MW, respectively. The objective of this study is to enhance a laser-driven impulse using a 300-J-class single pulsed laser owing to fluid-dynamic process. In this paper, we discuss a high-speed launch performance of a 1-gram projectile by enhanced impulse and achieved momentum coupling coefficient which are significantly improved using fluid-dynamic effect.

Watanabe, Keiko; Sasoh, Akihiro

2004-09-01

117

Risk Sensitive Impulse Control and Deterministic Games  

UK PubMed Central (United Kingdom)

We investigate the relationship between stochastic impulse control problemsand deterministic control problems. In particular, we study the problem ofcharacterizing the limit point of the value function of a stochastic impulse controlproblem as the variance of the underlying diffusion process tends to zero. In theconventional setting the limit point is found to be the value function of an appropriatedeterministic impulse control problem while in the risk-sensitive setting, where alogarithmic transform of the value function is the object of study, the limit point isfound to be the value function of an appropriate zero-sum differential game involvingimpulse controls.Keywords. Stochastic impulse control, Deterministic zero-sum differential games,Quasivariational inequalities, Viscosity solutions.1 IntroductionWe investigate the relationship between a class of stochastic optimal impulse controlproblems and deterministic control problems. In particular, we study the problem...

Peter Eichelsbacher

118

Cocaine-Induced Psychosis and Impulsivity in Cocaine-Dependent Patients.  

UK PubMed Central (United Kingdom)

Cocaine-dependent patients have high impulsiveness. Cocaine-induced psychosis is common among cocaine-dependent patients. Different risk factors associated with cocaine-induced psychosis have been reported. The aim of this study is to analyze the relationship between psychotic symptoms in cocaine-dependent patients and impulsivity and mental disorders characterized by impulsivity. This descriptive study included 287 outpatients with cocaine dependence according to the DSM-IV-TR criteria. The Structured Clinical Interview for DSM-IV Axis I and II, the Barratt Impulsiveness Scale, and a specific questionnaire on the presence of cocaine-induced psychosis were used to assess patients. Symptoms were observed in 59.9% of the study population. Total and cognitive impulsiveness scores obtained from the Barratt Impulsiveness Scale were significantly higher in patients with cocaine-induced psychosis. Individuals from this group reported more overdose incidents, initiated more treatments during their lifetime, and had a significantly greater prevalence of attention deficit hyperactivity disorder. Patients with cocaine-induced psychosis have a greater degree of impulsivity and a higher prevalence of attention deficit hyperactivity disorder. Thus, if these disorders are observed in cocaine-dependent participants, the presence of psychotic symptoms should be evaluated to prevent further occurrence and their consequences.

Roncero C; Daigre C; Grau-López L; Rodríguez-Cintas L; Barral C; Pérez-Pazos J; Gonzalvo B; Corominas M; Casas M

2013-07-01

119

Impulsivity moderates promotive environmental influences on adolescent delinquency: a comparison across family, school, and neighborhood contexts.  

UK PubMed Central (United Kingdom)

The present study examined moderating effects of impulsivity on the relationships between promotive factors from family (family warmth, parental knowledge), school (school connectedness), and neighborhood (neighborhood cohesion) contexts with delinquency using data collected from N?=?2,978 sixth to eighth graders from 16 schools surrounding a major city in the Midwestern United States. More than half of the respondents were non-Caucasian (M age ?=?12.48; 41.0 % male). Multilevel modeling analyses were conducted to take into account the clustering of the participants within schools. Impulsivity was positively associated with adolescent delinquency. Additionally, family warmth, parental knowledge, and school connectedness, but not neighborhood cohesion, were independently and inversely related to adolescent delinquency. Finally, impulsivity moderated relationships between family warmth and parental knowledge with delinquency but not relationships between school attachment and neighborhood cohesion with delinquency. Specifically, the negative relationship between family warmth and delinquency was significant for adolescents with high levels of, but not for those with below-average levels of, impulsivity. In addition, parental knowledge had a stronger association with decreased levels of delinquency for adolescents reporting higher levels of impulsivity. The moderating effects of impulsivity did not differ for males and females or for minority and non-minority participants. Findings indicate that impulsivity may have greater impact on adolescents' susceptibility to positive family influences than on their susceptibility to promotive factors from school or neighborhood contexts. Implications for future research and practice are discussed.

Chen P; Jacobson KC

2013-10-01

120

[Neurochemistry of impulsiveness and aggression].  

UK PubMed Central (United Kingdom)

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

Vetulani J

2013-01-01

 
 
 
 
121

Norepinephrine and impulsivity: effects of acute yohimbine.  

UK PubMed Central (United Kingdom)

RATIONALE: Rapid-response impulsivity, characterized by inability to withhold response to a stimulus until it is adequately appraised, is associated with risky behavior and may be increased in a state-dependent manner by norepinephrine. OBJECTIVE: We assessed effects of yohimbine, which increases norepinephrine release by blocking alpha-2 noradrenergic receptors, on plasma catecholamine metabolites, blood pressure, subjective symptoms, and laboratory-measured rapid-response impulsivity. METHODS: Subjects were 23 healthy controls recruited from the community, with normal physical examination and ECG, and negative history for hypertension, cardiovascular illness, and axis I or II disorder. Blood pressure, pulse, and behavioral measures were obtained before and periodically after 0.4 mg/kg oral yohimbine or placebo in a randomized, counterbalanced design. Metabolites of norepinephrine [3-methoxy-4-hydroxyphenylglycol (MHPG) and vanillylmandelic acid (VMA)] and dopamine [homovanillic acid (HVA)] were measured by high-pressure liquid chromatography with electrochemical detection. Rapid-response impulsivity was measured by commission errors and reaction times on the immediate memory task (IMT), a continuous performance test designed to measure impulsivity and attention. RESULTS: Yohimbine increased plasma MHPG and VMA but not HVA. Yohimbine increased systolic and diastolic blood pressure and pulse rate. On the IMT, yohimbine increased impulsive errors and impulsive response bias and accelerated reaction times. Yohimbine-associated increase in plasma MHPG correlated with increased impulsive response rates. Time courses varied; effects on blood pressure generally preceded those on metabolites and test performance. CONCLUSIONS: These effects are consistent with increased rapid-response impulsivity after pharmacological noradrenergic stimulation in healthy controls. Labile noradrenergic responses, or increased sensitivity to norepinephrine, may increase risk for impulsive behavior.

Swann AC; Lijffijt M; Lane SD; Cox B; Steinberg JL; Moeller FG

2013-09-01

122

Behavioral and cognitive impulsivity in obsessive-compulsive disorder and eating disorders.  

UK PubMed Central (United Kingdom)

This study compared self-reported impulsivity and neurocognitively assessed response inhibition in obsessive-compulsive disorder (OCD), eating disorder (ED), and healthy control participants. Participants completed the Barratt Impulsiveness Scale (BIS-11), stop-signal reaction time task, and measures of OCD and ED symptomatology (Yale-Brown Obsessive-Compulsive Scale and Eating Disorders Examination-Questionnaire). Compared to controls, both clinical groups reported higher levels of impulsivity on the BIS-11 however; only the OCD demonstrated increased stop-signal reaction time. Heightened levels of self-reported impulsivity may reflect the experience of anxiety in both OCD and ED populations whereas a lack of inhibitory control may represent a specific behavioral deficit in OCD.

Boisseau CL; Thompson-Brenner H; Caldwell-Harris C; Pratt E; Farchione T; Barlow DH

2012-12-01

123

Predicting impulsive self-injurious behavior in a sample of adult women.  

Science.gov (United States)

Different types of self-injury have been classified as reflecting impulsive and compulsive characteristics (article by Simeon and Favazza [Self-injurious Behaviors: Assessment and Treatment {pp 1-28}. Washington, DC: American Psychiatric Publishing, Inc, 2001]). The current research used a prospective design to evaluate whether there is a progression between these different types of self-injurious behaviors (SIB) over time. Support was found for a progression from compulsive SIB (including hair pulling, nail-biting, skin picking, scratching, and preventing wounds from healing) to impulsive SIB (including cutting, burning, carving, pin sticking, and punching) in a group of adult women (N = 106). Other factors hypothesized to be linked to this outcome were disordered eating, age, and personality facets of impulsivity (specifically, urgency and lack of perseverance). Of these variables, only urgency positively predicted impulsive SIB at the study's conclusion. These findings are discussed, limitations of the study are noted, and directions for future research are outlined. PMID:23274300

Black, Emma B; Mildred, Helen

2013-01-01

124

Eating disorders, substance use disorders, and impulsiveness among disordered gamblers in a community sample.  

UK PubMed Central (United Kingdom)

Disordered gambling and many eating disorders (EDs) involve recurrent loss of impulse control. We examined rates of specific EDs, ED psychopathology, substance use disorders, and their interrelationships with impulsiveness among community members with disordered gambling. Community-recruited adults with pathological (n?=?95) or problem (n?=?9) gambling (N?=?104; 51% female) completed structured interviews and questionnaires. We observed high rates of substance dependence, lifetime EDs, and current ED psychopathology; 20.8% of women (vs 1.9% of men) had a DSM-IV ED, and 37.8% (vs 3.9%) had an ED according to proposed DSM-5 criteria. Although disordered gambling severity was not associated with ED diagnosis or severity of ED psychopathology, greater disordered gambling severity and an ED diagnosis were both associated with increased impulsiveness. These findings suggest that impulsiveness might constitute a common personality characteristic that underlies disordered gambling and EDs.

von Ranson KM; Wallace LM; Holub A; Hodgins DC

2013-03-01

125

Predicting impulsive self-injurious behavior in a sample of adult women.  

UK PubMed Central (United Kingdom)

Different types of self-injury have been classified as reflecting impulsive and compulsive characteristics (article by Simeon and Favazza [Self-injurious Behaviors: Assessment and Treatment {pp 1-28}. Washington, DC: American Psychiatric Publishing, Inc, 2001]). The current research used a prospective design to evaluate whether there is a progression between these different types of self-injurious behaviors (SIB) over time. Support was found for a progression from compulsive SIB (including hair pulling, nail-biting, skin picking, scratching, and preventing wounds from healing) to impulsive SIB (including cutting, burning, carving, pin sticking, and punching) in a group of adult women (N = 106). Other factors hypothesized to be linked to this outcome were disordered eating, age, and personality facets of impulsivity (specifically, urgency and lack of perseverance). Of these variables, only urgency positively predicted impulsive SIB at the study's conclusion. These findings are discussed, limitations of the study are noted, and directions for future research are outlined.

Black EB; Mildred H

2013-01-01

126

Laser-surface impulse delivery in vacuum  

Energy Technology Data Exchange (ETDEWEB)

Available experimental measurements of impulse delivery to solid surfaces in vacuum by pulsed laser radiation are presented and compared to predictions of simple theoretical models. The trend of impulse coupling coefficient measurements with increasing laser fluence is explained by three regimes of the laser-material interaction process for vacuum or very low pressure conditions. The results indicate that impulsive coupling measurements can be simply scaled over a wide range of laser wavelengths, pulse lengths and focal spot sizes and coupling coefficients can be predicted with fair accuracy if the effective laser-surface absorption coefficient is known.

Lowder, J.E.

1982-01-01

127

Stability analysis of impulsive functional differential equations  

CERN Document Server

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

Stamova, Ivanka

2009-01-01

128

Pressure impulses during microsecond laser ablation.  

UK PubMed Central (United Kingdom)

The collapse of laser-induced cavitation bubbles creates acoustic transients within the surrounding medium and also pressure impulses to the ablation target and light-delivery fiber during microsecond laser ablation. The impulses are investigated here with time-resolved flash photography, and they are found to occur whether or not the light-delivery fiber is in contact with the target. We demonstrate that the impulses depend primarily on the energy stored in the cavitation bubble. They are not directly dependent on the mode of light delivery (contact versus noncontact), and they are also not directly correlated to the other acoustic transients. The pressure impulses do seem to be associated with the bubble-driven jet formation caused by the bubble collapse.

Shangguan H; Casperson LW; Prahl SA

1997-12-01

129

Pathological love: impulsivity, personality, and romantic relationship.  

UK PubMed Central (United Kingdom)

INTRODUCTION: Pathological love (PL)--behavior characterized by providing repetitive and uncontrolled care and attention to the partner in a romantic relationship--is a rarely studied condition, despite not being rare and causing suffering. This study aims at investigating impulsivity, personality, and characteristics related to the romantic relationship in this population. METHODS: Eighty-nine individuals (50 with PL; 39 individuals with no psychiatric disorder) were compared regarding impulsivity, personality, type of attachment, satisfaction with romantic relationship, and love style. RESULTS: Individuals with PL have higher levels of impulsivity (P<.001; Barratt Impulsiveness Scale), higher self-transcendence, that is, are more unconventional and hold sense of communion with a wider reality (P<.001; Temperament and Character Inventory) and keep dissatisfactory romantic relationships (P<.001; Adapted Relationship Assessment Scale). CONCLUSION: Individuals with PL present personality traits and relationship aspects that must be taken into account in devising assessment and therapeutic strategies for this population.

Sophia EC; Tavares H; Berti MP; Pereira AP; Lorena A; Mello C; Gorenstein C; Zilberman ML

2009-05-01

130

Muscarinic agonists to treat impulse control disorders  

UK PubMed Central (United Kingdom)

The invention relates to a novel use of compounds and pharmaceutically acceptable salts thereof, which are muscarinic, in particular muscarine-1 (M1) agonists. These compounds are useful for the preparation of medicaments for treatment, amelioration or prevention of impulse control disorders. These include impulse control disorders 'Not Elsewhere Classified' such as intermittent explosive disorder, pyromania, kleptomania, pathological gambling and trichotillomania and impulse control disorders 'Not Otherwise Specified' such as: compulsive buying disorder, binge eating and binge drinking disorder, impulsive self-injurious behaviour such as pathological skin picking, nail-biting and nose-picking, gouging, head banging and self- biting paraphilic sexual addictions, including exhibitionism, fetishism, frotteurism, pedophilia, masochism, sadism, transvestic fetishism and voyeurism compulsive Internet use and excessive mobile phone use.

131

Impulsive nature in collisional driven reconnection  

Energy Technology Data Exchange (ETDEWEB)

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

Kitabata, Hideyuki; Hayashi, Takaya; Sato, Tetsuya

1995-11-01

132

Hybrid Impulsive Control for Closed Quantum Systems  

Science.gov (United States)

The state transfer problem of a class of nonideal quantum systems is investigated. It is known that traditional Lyapunov methods may fail to guarantee convergence for the nonideal case. Hence, a hybrid impulsive control is proposed to accomplish a more accurate convergence. In particular, the largest invariant sets are explicitly characterized, and the convergence of quantum impulsive control systems is analyzed accordingly. Numerical simulation is also presented to demonstrate the improvement of the control performance.

Sun, Jitao; Lin, Hai

2013-01-01

133

Robust Impulsive Synchronization of Discrete Dynamical Networks  

Directory of Open Access Journals (Sweden)

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

Ming Lei; Bin Liu

2008-01-01

134

Impulsivity in suicidal and nonsuicidal adolescents.  

UK PubMed Central (United Kingdom)

Nonsuicidal and suicidal adolescent inpatients were compared to community high school students using behavioral measures of impulsivity. Measures of problem solving ability, hopelessness, and depression were also administered to all groups. The suicidal inpatients were characterized by greater impulsivity, hopelessness, and depression than both nonsuicidal inpatients and community high school students. There were no differences in problem-solving abilities found between the suicidal inpatients and either the nonsuicidal inpatients or the community controls.

Kashden J; Fremouw WJ; Callahan TS; Franzen MD

1993-06-01

135

Hybrid impulsive control for closed quantum systems.  

UK PubMed Central (United Kingdom)

The state transfer problem of a class of nonideal quantum systems is investigated. It is known that traditional Lyapunov methods may fail to guarantee convergence for the nonideal case. Hence, a hybrid impulsive control is proposed to accomplish a more accurate convergence. In particular, the largest invariant sets are explicitly characterized, and the convergence of quantum impulsive control systems is analyzed accordingly. Numerical simulation is also presented to demonstrate the improvement of the control performance.

Zhao S; Sun J; Lin H

2013-01-01

136

Impulse control disorders in Parkinson's disease.  

UK PubMed Central (United Kingdom)

Impulse control disorders (ICDs), a group of complex behavioral disorders, occur more commonly in Parkinson's disease (PD) patients than in the general population, with a reported prevalence up to 13.6% in some studies. The most common ICDs reported are pathological gambling (PG), hypersexuality (HS), compulsive shopping and compulsive eating. More than a quarter of the patients with ICDs have 2 or more behavioral addictions. These abnormal behaviors impair activities of daily living and have a negative impact on quality of life of patients and their families. As with many other non motor symptoms in PD, ICDs are frequently under-reported by patients and caregivers and may be under-recognized by the treating physicians. Treatment with dopamine agonists (DA) is the main risk factor for developing ICDs, and stimulation of mesolimbic D3 receptors by DA is thought to underlie their development. The DA effect seems to be a class effect and not specific for any DA. Levodopa can also induce ICDs but much less so than the DAs. The management of ICDs in PD is complex. Modifications in dopaminergic drug treatment are frequently necessary. In some cases alternative therapies such as atypical antipsychotics, antidepressants or deep brain stimulation if motor symptoms become incapacitating after adjustment of dopamine replacement therapy should be considered.

Vilas D; Pont-Sunyer C; Tolosa E

2012-01-01

137

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; Meral BERKEM

2012-01-01

138

Enhanced awakening probability of repetitive impulse sounds.  

Science.gov (United States)

In the present study relations between the level of impulse sounds and the observed proportion of behaviorally confirmed awakening reactions were determined. The sounds (shooting sounds, bangs produced by door slamming or by container transshipment, aircraft landings) were presented by means of loudspeakers in the bedrooms of 50 volunteers. The fragments for the impulse sounds consisted of single or multiple events. The sounds were presented during a 6-h period that started 75?min after the subjects wanted to sleep. In order to take account of habituation, each subject participated during 18 nights. At equal indoor A-weighted sound exposure levels, the proportion of awakening for the single impulse sounds was equal to that for the aircraft sounds. The proportion of awakening induced by the multiple impulse sounds, however, was significantly higher. For obtaining the same rate of awakening, the sound level of each of the successive impulses in a fragment had to be about 15-25?dB lower than the level of one single impulse. This level difference was largely independent of the degree of habituation. Various explanations for the enhanced awakening probability are discussed. PMID:23967934

Vos, Joos; Houben, Mark M J

2013-09-01

139

Enhanced awakening probability of repetitive impulse sounds.  

UK PubMed Central (United Kingdom)

In the present study relations between the level of impulse sounds and the observed proportion of behaviorally confirmed awakening reactions were determined. The sounds (shooting sounds, bangs produced by door slamming or by container transshipment, aircraft landings) were presented by means of loudspeakers in the bedrooms of 50 volunteers. The fragments for the impulse sounds consisted of single or multiple events. The sounds were presented during a 6-h period that started 75?min after the subjects wanted to sleep. In order to take account of habituation, each subject participated during 18 nights. At equal indoor A-weighted sound exposure levels, the proportion of awakening for the single impulse sounds was equal to that for the aircraft sounds. The proportion of awakening induced by the multiple impulse sounds, however, was significantly higher. For obtaining the same rate of awakening, the sound level of each of the successive impulses in a fragment had to be about 15-25?dB lower than the level of one single impulse. This level difference was largely independent of the degree of habituation. Various explanations for the enhanced awakening probability are discussed.

Vos J; Houben MM

2013-09-01

140

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

Directory of Open Access Journals (Sweden)

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

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

2013-01-01

 
 
 
 
141

Impulsive control and synchronization of the Lorenz systems family  

International Nuclear Information System (INIS)

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

2007-01-01

142

Volatility Impulse Response Functions for Multivariate Garch Models  

UK PubMed Central (United Kingdom)

In the empirical analysis of financial time series, multivariate GARCH models havebeen used in various forms.As it is typical for nonlinear models there is yet nounique framework available to uncover dynamic covariance relationships for vectorreturn processes.We introduce a new concept of impulse response functions tracingthe e#ects of independent shocks on volatility through time.The advocatedmethodology avoids typical orthogonalization and ordering problems.Theoreticalproperties of volatility impulse response functions are derived and compared withconditional moment profiles introduced by Gallant, Rossi and Tauchen(1LLM forsemi-nonparametric models.In an empirical study of a bivariate foreign exchangerate series we use volatility impulse response functions to compare alternative parametricvolatility specifications.It is shown that for shocks a#ecting foreign exchangerates in an asymmetric way, the di#erence between our methodology and conditionalvolatility profiles can be substantial.Keywords: Multivariate GARCH, impulse response, exchange rate, volatilityJEL Classification: C221Electrabel, R&D Energy Markets, Place de l'Universite1E B-1J: Louvain-la-Neuve, Belgium.emailchristian.haff.2Institut fur Statistik und Okonometrie, Wirtschaftswissenschaftliche Fakultat, Humboldt--Universitatzu Berlin,SpandauerStr.1 D-11uBerlin, Germany. e-mail helmut@wiwi.hu-berlin.de.This paper is a revised version of CORE discussion paper 9847.Both authors would like to thank LucBauwens, Jeroen Rombouts and Helmut Lutkepohl for helpful comments.Financial support by theBelgian Government and the Deutsche Forschungsgemeinschaft is gratefully acknowledged.This text presents research results of the Belgian Program on Interuniversity Poles of At...

Mu Tivariate; Garch Models; Christian M. Hafner

143

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

2013-01-01

144

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

Science.gov (United States)

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

Masse, Louis Philippe

145

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. pMAOA uVNTR; (4) 5-HTTLPR and rs6313 and (5) HTR1B (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

2012-06-23

146

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

UK PubMed Central (United Kingdom)

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. p<.01 and False Discovery Rate <.10) interactions between (1) gender and TPH2 (rs1386483) genotype; (2) gender and HTR2A (rs6313) genotype; and epistatic interactions among (3) 5-HTTLPR and MAOA uVNTR; (4) 5-HTTLPR and rs6313 and (5) HTR1B (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.

Stoltenberg SF; Christ CC; Highland KB

2012-10-01

147

Exponential synchronization of linearly coupled neural networks with impulsive disturbances.  

UK PubMed Central (United Kingdom)

This brief investigates globally exponential synchronization for linearly coupled neural networks (NNs) with time-varying delay and impulsive disturbances. Since the impulsive effects discussed in this brief are regarded as disturbances, the impulses should not happen too frequently. The concept of average impulsive interval is used to formalize this phenomenon. By referring to an impulsive delay differential inequality, we investigate the globally exponential synchronization of linearly coupled NNs with impulsive disturbances. The derived sufficient condition is closely related with the time delay, impulse strengths, average impulsive interval, and coupling structure of the systems. The obtained criterion is given in terms of an algebraic inequality which is easy to be verified, and hence our result is valid for large-scale systems. The results extend and improve upon earlier work. As a numerical example, a small-world network composing of impulsive coupled chaotic delayed NN nodes is given to illustrate our theoretical result.

Lu J; Ho DW; Cao J; Kurths J

2011-02-01

148

How many impulsivities? A discounting perspective.  

UK PubMed Central (United Kingdom)

People discount the value of delayed and uncertain outcomes, and how steeply individuals discount is thought to reflect how impulsive they are. From this perspective, steep discounting of delayed outcomes (which fails to maximize long-term welfare) and shallow discounting of probabilistic outcomes (which fails to adequately take risk into account) reflect the same trait of impulsivity. Despite the fact that a hyperboloid function describes the discounting of both delayed and probabilistic outcomes, there is considerable evidence that the two kinds of discounting involve different processes as well as separate impulsivity traits. Several manipulations differentially affect delay and probability discounting, and correlational studies show that how steeply one discounts delayed rewards is relatively independent of how steeply one discounts probabilistic rewards. Moreover, people's discounting of delayed money and health outcomes are uncorrelated as are discounting of real, consumable rewards and hypothetical money. These results suggest that even within delay discounting, there may be multiple 'impulsivities,' each of which may be important for understanding a different aspect of decision making. Taken together, the pattern of findings reviewed here argues for a more nuanced view of impulsivity than that which is usually assumed in discounting research.

Green L; Myerson J

2013-01-01

149

Spatiotemporal impulse response and cortical magnification.  

UK PubMed Central (United Kingdom)

According to a model of the spatiotemporal weighting function (Manahilov, V. Spatiotemporal visual response at suprathreshold stimuli. Vision Research, 1995, 35, 227-237; and Triphasic temporal impulse responses and Mach bands in time. Vision Research, 38, 447-458) the waveform of the temporal-impulse response and the cortical spread of the spatial-impulse response should not depend on the retinal site of stimulation. To verify these model predictions, the spatiotemporal responses to brief near-threshold lines presented in the fovea and the near retinal periphery were studied. The effect of an inducing stimulus on the threshold for pattern detection of a test stimulus was measured, assuming that the pattern-detection threshold was determined by the test peak response. The spatial spread of the line response expressed in visual-field units was increased with eccentricity. The temporal-impulse responses to foveal and peripheral stimuli were similar. The model of the weighting function was used to evaluate the relative magnification factor for the retinal location tested. The calculated cortical spatial-impulse responses did not depend on the stimulation site. The data obtained are in line with the cortical magnification theory of peripheral vision.

Manahilov V; Atanassova S

1998-04-01

150

Impulsivity and apathy in Parkinson's disease.  

Science.gov (United States)

Impulse control disorders (ICDs) and apathy are recognized as two important neuropsychiatric syndromes associated with Parkinson's disease (PD), but as yet we understand very little about the cognitive mechanisms underlying them. Here, we review emerging findings, from both human and animal studies, that suggest that impulsivity and apathy are opposite extremes of a dopamine-dependent spectrum of motivated decision making. We first argue that there is strong support for a hypodopaminergic state in PD patients with apathy, as well as for an association between dopamine therapy and development of ICDs. However, there is little evidence for a clear dose-response relationship, and great heterogeneity of findings. We argue that dopaminergic state on its own is an insufficient explanation, and suggest instead that there is now substantial evidence that both apathy and impulsivity are in fact multi-dimensional syndromes, with separate, dissociable mechanisms underlying their 'surface' manifestations. Some of these mechanisms might be dopamine-dependent. According to this view, individuals diagnosed as impulsive or apathetic may have very different mechanisms underlying their clinical states. We propose that impulsivity and apathy can arise from dissociable deficits in option generation, option selection, action initiation or inhibition and learning. Review of the behavioural and neurobiological evidence leads us to a new conceptual framework that might help understand the variety of functional deficits seen in PD. PMID:23621377

Sinha, Nihal; Manohar, Sanjay; Husain, Masud

2013-04-29

151

Kalman filter algorithm for digitally recorded lightning impulse parameter evaluation  

Energy Technology Data Exchange (ETDEWEB)

Relevant standards establish the construction of a mean curve in lightning impulses with perturbations (oscillations, overshoot, noise) in order to determine impulse characteristic parameters (peak value, front time, time to half-value and voltage at the instant of chopping and time to chopping if it is the case). A new method for constructing a mean curve in lightning impulses that uses an extended Kalman filter is described. This method needs a model for the mean curve or smooth impulse. A smooth impulse model based on existing ones is adopted. Results obtained with mathematical and real impulses are presented.

Perez, J.; Martinez, J. [Univ. Politecnica de Madrid (Spain)

1996-10-01

152

Is premature ejaculation an impulse control disorder?  

UK PubMed Central (United Kingdom)

Premature ejaculation (PE) is defined as persistent or recurrent ejaculation with minimal sexual stimulation that occurs before the participant wishes to ejaculate and is associated with marked distress or interpersonal difficulty. Impulse control disorders (ICDs) are grouped as a heterogeneous cluster of disorders linked by a "failure to resist" impulses to engage in harmful, disturbing or distressing behaviours. I hypothesise that premature ejaculation is an impulse control disorder. ICDs share features with PE aspects of impaired control, rapid responses to stimuli and hypersensitivity. These disorders often occur with subjective and social distress for patients. In addition to these features, the neurotransmitter systems have been similarly implicated in ICDs and PE. The same treatment options further support a relationship between ICDs and PE. The behaviours likely exist on a spectrum.

Ozdemir Ö

2012-07-01

153

Micropower impulse radar technology and applications  

Energy Technology Data Exchange (ETDEWEB)

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

Mast, J., LLNL

1998-04-15

154

Impulsive differential equations with a small parameter  

CERN Multimedia

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

Bainov, DD

1994-01-01

155

Impulse control disorders in Parkinson's disease  

Directory of Open Access Journals (Sweden)

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

XIE An-mu; LI Yong-sheng; HAN Xun

2013-01-01

156

International comparison of HV impulse measuring systems  

Energy Technology Data Exchange (ETDEWEB)

Present standards for qualifying HV impulse measuring systems by unit-step-response parameters are complex and difficult to apply and some systems, which have response parameters within the limits of the standards, have unacceptable errors. This paper takes the first step in providing a simplified method based on simultaneous measurements of an HV impulse by a reference system and the system under test. Comparative measurements have been made in four National Laboratories and the relative differences are reported. The results are discussed and the further work which is required is outlined.

McComb, T.R.; Hughes, R.C.; Lightfoot, H.A.; Schon, K.; Schulte, R.; McKnight, R.; Zhang, Y.X.

1989-04-01

157

Presentation of solutions of impulsive fractional Langevin equations and existence results. Impulsive fractional Langevin equations  

Science.gov (United States)

In this paper, a class of impulsive fractional Langevin equations is firstly offered. Formula of solutions involving Mittag-Leffler functions and impulsive terms of such equations are successively derived by studying the corresponding linear Langevin equations with two different fractional derivatives. Meanwhile, existence results of solutions are established by utilizing boundedness, continuity, monotonicity and nonnegative of Mittag-Leffler functions and fixed point methods. Further, other existence results of nonlinear impulsive problems are also presented. Finally, an example is given to illustrate our theoretical results.

Wang, J.; Fec?kan, M.; Zhou, Y.

2013-09-01

158

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

UK PubMed Central (United Kingdom)

Current theories in economics, marketing, and psychology fail to explain underlying reasons for impulse buying and, crucially, why certain goods (e.g., clothes) are bought impulsively more than others (e.g., basic kitchen equipment). We propose and examine a social psychological model, which predicts that people impulse buy to acquire material symbols of personal and social identity. We predict that consumers will differ systematically in the goods they buy on impulse, and in their reasons for doing so, depending on their attitudes towards shopping, and also along important social categories, such as gender. Specifically, our theoretical model-drawing on a social constructionist model of material possessions (e.g., Dittmar, 1992) and symbolic self-completion theory (e.g. Wicklund and Gollwitzer, 1982)-leads to three sets of hypotheses: (i) some consumer durables are more likely to be bought on impulse than others, and there may be gender differences in object choices, (ii) differences will emerge in the buying considerations (e.g., functional, emotional, symbolic) that are used for impulse and planned buying, and (iii) magnitude of self-discrepancies will predict relative impulse buying frequency and the buying considerations used, if the individual uses consumption as a self-completion strategy. These predictions were expected to hold particularly strongly for individuals high in compulsive shopping tendencies. We test our model in a questionnaire study with a sample of British consumers (n = 61). The results lend support to all three sets of hypotheses. The implications of these findings are discussed with respect to economic and consumer theory, and the treatment offered to the increasing number of 'addicted' shoppers.

Dittmar H; Beattie J; Friese S

1996-09-01

159

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

Science.gov (United States)

Current theories in economics, marketing, and psychology fail to explain underlying reasons for impulse buying and, crucially, why certain goods (e.g., clothes) are bought impulsively more than others (e.g., basic kitchen equipment). We propose and examine a social psychological model, which predicts that people impulse buy to acquire material symbols of personal and social identity. We predict that consumers will differ systematically in the goods they buy on impulse, and in their reasons for doing so, depending on their attitudes towards shopping, and also along important social categories, such as gender. Specifically, our theoretical model-drawing on a social constructionist model of material possessions (e.g., Dittmar, 1992) and symbolic self-completion theory (e.g. Wicklund and Gollwitzer, 1982)-leads to three sets of hypotheses: (i) some consumer durables are more likely to be bought on impulse than others, and there may be gender differences in object choices, (ii) differences will emerge in the buying considerations (e.g., functional, emotional, symbolic) that are used for impulse and planned buying, and (iii) magnitude of self-discrepancies will predict relative impulse buying frequency and the buying considerations used, if the individual uses consumption as a self-completion strategy. These predictions were expected to hold particularly strongly for individuals high in compulsive shopping tendencies. We test our model in a questionnaire study with a sample of British consumers (n = 61). The results lend support to all three sets of hypotheses. The implications of these findings are discussed with respect to economic and consumer theory, and the treatment offered to the increasing number of 'addicted' shoppers. PMID:8826795

Dittmar, H; Beattie, J; Friese, S

1996-09-01

160

The role of impulsivity in self-mutilators, suicide ideators and suicide attempters - a study of 1265 male incarcerated individuals.  

UK PubMed Central (United Kingdom)

OBJECTIVE: We explored differences between high and low-impulsive incarcerated individuals in the context of lifetime self-mutilation, suicide ideation and suicide attempt. METHODS: A total of 1265 males detained in Italian penitentiary institutions were studied between January 2006 and December 2008. The study raters were specifically trained to discriminate between suicide attempters, ideators and self-mutilators. Participants completed the Barratt Impulsivity Scale, Childhood Trauma Questionnaire (CTQ), Eysenck Personality Questionnaire (EPQ), Connor-Davidson Resilience Scale (CD-RISC), Brown-Goodwin Assessment for Lifetime History of Aggression (BGLHA) and Buss and Durkee Hostility Inventory (BDHI). Based on BIS 7 total score distribution, two extreme quarters - high-impulsive group (n=306) and low-impulsive group (n=285) - were compared. RESULTS: Over 42% of participants had lifetime suicide ideation, 13% attempted suicide and 17% were self-mutilators. High-impulsive subjects were younger, more often single and with more prominent psychoticism, extraversion, aggression, hostility and resilience capacity. They were more frequently diagnosed with substance use disorders and engaged in self-mutilating behaviour. There was no difference in the rate of suicide attempts between the two groups. CONCLUSION: Although high-impulsive subjects were more prone to suicidal behaviour, it was not predicted by higher impulsivity when other psychological variables were accounted for.

Carli V; Jovanovi? N; Podlesek A; Roy A; Rihmer Z; Maggi S; Marusic D; Cesaro C; Marusic A; Sarchiapone M

2010-06-01

 
 
 
 
161

Similar effects of the selective noradrenaline reuptake inhibitor atomoxetine on three distinct forms of impulsivity in the rat.  

UK PubMed Central (United Kingdom)

Atomoxetine is a noradrenaline-specific reuptake inhibitor used clinically for the treatment of childhood and adult attention deficit hyperactivity disorder (ADHD). Studies in human volunteers and patient groups have shown that atomoxetine improves stop-signal reaction time (SSRT) performance, an effect consistent with a reduction in motor impulsivity. However, ADHD is a heterogeneous disorder and it is of interest to determine whether atomoxetine is similarly effective against other forms of impulsivity, as well as the attentional impairment present in certain subtypes of ADHD. The present study examined the effects of atomoxetine on impulsivity using an analogous SSRT task in rats and two additional tests of impulsivity; delay discounting of reward and the five-choice serial reaction time task (5CSRTT), the latter providing an added assessment of sustained visual attention. Atomoxetine produced a significant dose-dependent speeding of SSRT. In addition, atomoxetine produced a selective, dose-dependent decrease in premature responding on the 5CSRTT. Finally, on the delay-discounting task, atomoxetine significantly decreased impulsivity by increasing preference for the large-value reward across increasing delay. These findings conclusively demonstrate that atomoxetine decreases several distinct forms of impulsivity in rats. The apparent contrast of these effects with stimulant drugs such as amphetamine and methylphenidate, which generally act to increase impulsivity on the 5CSRTT, may provide new insights into the mechanisms of action of stimulant and nonstimulant drugs in ADHD.

Robinson ES; Eagle DM; Mar AC; Bari A; Banerjee G; Jiang X; Dalley JW; Robbins TW

2008-04-01

162

Similar effects of the selective noradrenaline reuptake inhibitor atomoxetine on three distinct forms of impulsivity in the rat.  

Science.gov (United States)

Atomoxetine is a noradrenaline-specific reuptake inhibitor used clinically for the treatment of childhood and adult attention deficit hyperactivity disorder (ADHD). Studies in human volunteers and patient groups have shown that atomoxetine improves stop-signal reaction time (SSRT) performance, an effect consistent with a reduction in motor impulsivity. However, ADHD is a heterogeneous disorder and it is of interest to determine whether atomoxetine is similarly effective against other forms of impulsivity, as well as the attentional impairment present in certain subtypes of ADHD. The present study examined the effects of atomoxetine on impulsivity using an analogous SSRT task in rats and two additional tests of impulsivity; delay discounting of reward and the five-choice serial reaction time task (5CSRTT), the latter providing an added assessment of sustained visual attention. Atomoxetine produced a significant dose-dependent speeding of SSRT. In addition, atomoxetine produced a selective, dose-dependent decrease in premature responding on the 5CSRTT. Finally, on the delay-discounting task, atomoxetine significantly decreased impulsivity by increasing preference for the large-value reward across increasing delay. These findings conclusively demonstrate that atomoxetine decreases several distinct forms of impulsivity in rats. The apparent contrast of these effects with stimulant drugs such as amphetamine and methylphenidate, which generally act to increase impulsivity on the 5CSRTT, may provide new insights into the mechanisms of action of stimulant and nonstimulant drugs in ADHD. PMID:17637611

Robinson, Emma S J; Eagle, Dawn M; Mar, Adam C; Bari, Andrea; Banerjee, Gargi; Jiang, Xiaosu; Dalley, Jeffrey W; Robbins, Trevor W

2007-07-18

163

A new Calculation Procedure for Spatial Impulse Responses in Ultrasound  

DEFF Research Database (Denmark)

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

Jensen, JØrgen Arendt

1999-01-01

164

Leupeptin reduces impulse noise induced hearing loss  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Background Exposure to continuous and impulse noise can induce a hearing loss. Leupeptin is an inhibitor of the calpains, a family of calcium-activated proteases which promote cell death. The objective of this study is to assess whether Leupeptin could reduce the hearing lo...

Gavriel Haim; Shulman Abraham; Stracher Alfred; Sohmer Haim

165

Impulsive behavior in online groceries retail  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The impulsive behavior phenomenon has been extensively studied during the last decades. However, the online version of this behavior is a relatively new concept and there are few studies that try to explain and redefine this concept for the World Wide Web (Madhavaram and Laverie 2003, Zhang, Prybuto...

Silva, Sara Alexandra Ribeiro Martins e

166

The Relationship among Spontaneity, Impulsivity, and Creativity  

Science.gov (United States)

|The present study was designed to investigate two characteristics of spontaneity, its relationship to creativity and to impulsivity. We hypothesized a positive relationship between spontaneity and creativity, consistent with Moreno, 1953 "canon of spontaneity-creativity." We also predicted a negative relationship between spontaneity and…

Kipper, David A.; Green, Doreen J.; Prorak, Amanda

2010-01-01

167

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 ...

Lecointre, Aubin; Dragomirescu, Daniela; Plana, Robert

168

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; S. I. Kostadinov; N. Van Minh; N. Hong Thai; P. P. Zabreiko

1992-01-01

169

ADHD-hyperactive/impulsive subtype in adults  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This is the first study to evaluate ADHD-hyperactive/impulsive subtype in a large clinical sample of adults with ADHD. The Quality of Life, Effectiveness, Safety and Tolerability (QuEST) study included 725 adults who received clinician diagnoses of any ADHD subtype. Cross-sectional baseline data fro...

Christopher Gibbins; Margaret D. Weiss; David W. Goodman; Paul S. Hodgkins; Jeanne M. Landgraf; Stephen V. Faraone

170

Continuum of impulsiveness caused by auditory masking.  

UK PubMed Central (United Kingdom)

OBJECTIVE: Impulsivity is a hallmark of attention deficit/hyperactivity disorder (ADHD). Various auditory masking procedures can quantify the impulsivity caused by distracting background sounds. This study compares the impulsiveness and distraction caused by informational masking (unpredictable tones) with previously published data on central masking (contralateral noise) in children with and without ADHD. METHODS: Twenty-six normal and 14 children diagnosed as having ADHD (combined type), all between the ages of 7 and 13, indicated whether they heard a 512-ms, 500-Hz pure tone in a single-interval task under conditions of informational masking and in quiet. The masker consisted of 10 randomly selected frequencies between 1,000 and 2,500 Hz presented simultaneously at an overall level of 60 dB SPL. A maximum-likelihood method estimated thresholds and false alarm rates. RESULTS: There were no differences due to ADHD in thresholds or false alarm rates either with informational masking or in quiet. With informational masking, normal children had high false alarm rates, similar to those from children with ADHD under central masking. With informational masking, all children tended to say a stimulus was present when it was not. CONCLUSIONS: All children behave impulsively under some conditions. Pediatric patients with attention disorders can thus be reassured that impulsiveness with unpredictable background sounds is normal, to some extent. Response biases of children with ADHD may only diverge from normal in situations where distracting external stimuli have an intermediate level of predictability. A previous study showed that with central masking, children with ADHD are more impulsive than normal. There appears to be a limit to the uncertainty in auditory masking that can be tolerated by children. Children with ADHD become impulsive at lower levels of uncertainty than normal. Increasing the predictability of distracting background sounds may thus improve the performance of children with ADHD. Informational masking may, for normal listeners, mimic something of what it is like to have an attention deficit. ADHD can be profitably studied with auditory tasks.

Gray LC; Breier JI; Foorman BR; Fletcher JM

2002-12-01

171

Analysis of Caputo impulsive fractional order differential equations with applications  

CERN Multimedia

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

Mahto, Lakshman; Favini, Angelo

2012-01-01

172

Impulse-response analysis of the market share attraction model  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We propose a simulation-based technique to calculate impulse-response functions and their confidence intervals in a market share attraction model [MCI]. As an MCI model implies a reduced form model for the logs of relative market shares, simulation techniques have to be used to obtain the impulse-r...

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

173

On Exact Controllability of First-Order Impulsive Differential Equations  

Directory of Open Access Journals (Sweden)

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

Nieto JuanJ; Tisdell ChristopherC

2010-01-01

174

The relationship between impulsivity and craving in alcohol dependent patients.  

UK PubMed Central (United Kingdom)

RATIONALE: Impulsivity and craving are both associated with higher relapse rates and a worse prognosis in patients with a substance use disorder, but the relationship between these two phenomena has been largely ignored in the field of alcohol use disorders. OBJECTIVES: The primary aim of this study was to investigate the relationship between different dimensions of impulsivity and different forms of self-reported craving. Additionally, the influence of the severity of alcohol dependence on impulsivity, craving, and on their relationship was exploed. METHODS: Impulsivity and craving levels were investigated in 87 abstinent alcohol-dependent (AD) patients using a broad range of self-report questionnaires and behavioral impulsivity measures. Alcohol use was measured by means of the timeline followback method. RESULTS: Higher scores of emotional craving (Alcohol Urge Questionnaire-AUQ) were significantly related to higher self-reported impulsivity (Barratt Impulsiveness Scale, version 11) and to higher cognitive impulsivity (information sampling task). Additionally, exploratory analyses suggest that these relationships are more pronounced in severe AD patients compared to less severe AD patients. No significant relationships were found between emotional craving (AUQ) and motor impulsivity (stop signal task) or delay discounting and between obsessive-compulsive craving (Obsessive Compulsive Drinking Scale) and measures of impulsivity. CONCLUSIONS: Emotional craving is related to self-reported impulsivity and to cognitive impulsivity. These relationships seem to be more pronounced in AD patients with severe alcohol dependence. Further research is needed to explore the effect of this relationship on treatment outcome and relapse.

Joos L; Goudriaan AE; Schmaal L; De Witte NA; Van den Brink W; Sabbe BG; Dom G

2013-03-01

175

Nonlinear impulsive Volterra integral equations in Banach spaces and applications  

Directory of Open Access Journals (Sweden)

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

Dajun Guo

1993-01-01

176

New stability criterion for delayed neural networks with impulses  

International Nuclear Information System (INIS)

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

2008-01-01

177

An improved approximation for the spatial impulse response of a rectangular transducer.  

Science.gov (United States)

One common approximation for a field point located in the far field of the transducer is to trapezoidally-shaped function to approximate the true spatial impulse response. A quadrilaterally shaped function is proposed here. The quadrilaterally shaped function also includes the trapezoidally shaped function as a special case. This paper shows that the quadrilateral approximation applied in the specifically defined field location is superior to the trapezoidal approximation for the true spatial impulse response function when the transducer elements have the aspect ratio of approximately 10, typical of those found in 1.5 D arrays. PMID:18244160

Teo, T J

1998-01-01

178

An improved approximation for the spatial impulse response of a rectangular transducer.  

UK PubMed Central (United Kingdom)

One common approximation for a field point located in the far field of the transducer is to trapezoidally-shaped function to approximate the true spatial impulse response. A quadrilaterally shaped function is proposed here. The quadrilaterally shaped function also includes the trapezoidally shaped function as a special case. This paper shows that the quadrilateral approximation applied in the specifically defined field location is superior to the trapezoidal approximation for the true spatial impulse response function when the transducer elements have the aspect ratio of approximately 10, typical of those found in 1.5 D arrays.

Teo TJ

1998-01-01

179

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

180

Impulsive responses to positive mood and reward are related to mania risk.  

UK PubMed Central (United Kingdom)

Bipolar disorder is characterised by impulsivity, and recent research suggests it is important to consider more specific forms of impulsivity. In two student samples, we examined associations of self-reported impulsivity with mania risk (Hypomanic Personality Scale, HPS). We hypothesised that mania risk would relate to impulsivity in the context of opportunities for rewarding activities (delaying gratification inventory, DGI), reward pursuit (Fun-Seeking subscale of the behavioural activation scale, BAS), and when experiencing positive affect (positive urgency measure, PUM). In Study 1 (N=823), the HPS was uniquely related to fun-seeking and PUM scores. Study 2 (N=482) replicated the correlation of HPS scores with PUM while documenting positive associations between PUM and trait-like responses to positive affect. Findings across both studies stress the importance of considering the role of positive emotion in driving the impulsivity among persons at risk for mania. These findings have implications for refining our understanding of the aetiology of bipolar disorder and for treatment development.

Giovanelli A; Hoerger M; Johnson SL; Gruber J

2013-01-01

 
 
 
 
181

Can the distinction between intentional and unintentional interference control help differentiate varieties of impulsivity?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

It has recently been shown that perseverance specifically relates to resisting proactive interference [Gay, P., Rochat, L., Billieux, J., d'Acremont, M., & Van der Linden, M. (2008). Heterogeneous inhibition processes involved in different facets of self-reported impulsivity: Evidence from a communi...

Philippe, Gay; Courvoisier, Delphine S.; Billieux, Joël; Rochat, Lucien; Schmidt, Ralph E.; Van der Linden, Martial

182

ADHD-hyperactive/impulsive subtype in adults  

Directory of Open Access Journals (Sweden)

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

Christopher Gibbins; Margaret D. Weiss; David W. Goodman; Paul S. Hodgkins; Jeanne M. Landgraf; Stephen V. Faraone

2010-01-01

183

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

UK PubMed Central (United Kingdom)

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

Riemer S; Mills DS; Wright H

2013-10-01

184

Impulsive personality traits in male pedophiles versus healthy controls: is pedophilia an impulsive-aggressive disorder?  

UK PubMed Central (United Kingdom)

Pedophilia is characterized by sexual attraction to prepubescent children. Despite the extensive literature documenting the pervasive and pernicious effects of childhood sexual abuse, there is surprisingly little psychiatric literature on pedophilia and its etiology remains enigmatic. In recent years, the psychiatric literature on the phenomenology, neurobiology, and treatment of impulsive-aggressive disorders has grown significantly. As some investigators have conceptualized pedophilia as an impulsive-aggressive disorder, it is of interest whether recent advances in the study of impulsive-aggressive disorders might shed light on pathological mechanisms underlying pedophilia. In the following study, 20 male subjects with a DSM-IV diagnosis of pedophilia, heterosexual type were recruited from an outpatient facility for sexual offenders and compared to 24 demographically similar control subjects. Groups were compared on three personality instruments--the Millon Clinical Multiaxial Inventory-II (MCMI-II), the Temperament and Character Inventory (TCI), and the Dimensional Assessment of Personality Impairment-Questionnaire (DAPI-Q)--to assess for select impairment in impulsive-aggressive personality traits. Pedophiles showed severe and pervasive personality impairment relative to controls. Although there was evidence of impulsivity, the findings do not suggest a predominance of impulsive-aggressive traits, and in fact provide evidence of inhibition, passive-aggression, and harm avoidance. The notion of "compulsive-aggression" in pedophilia is proposed.

Cohen LJ; Gans SW; McGeoch PG; Poznansky O; Itskovich Y; Murphy S; Klein E; Cullen K; Galynker II

2002-03-01

185

Is impulsivity a common trait in bipolar and unipolar disorders?  

UK PubMed Central (United Kingdom)

OBJECTIVES: ? Impulsivity is increased in bipolar and unipolar disorders during episodes and is associated with substance abuse disorders and suicide risk. Impulsivity between episodes predisposes to relapses and poor therapeutic compliance. However, there is little information about impulsivity during euthymia in mood disorders. We sought to investigate trait impulsivity in euthymic bipolar and unipolar disorder patients, comparing them to healthy individuals and unaffected relatives of bipolar disorder patients. METHODS: ? Impulsivity was evaluated by the Barratt Impulsiveness Scale (BIS-11A) in 54 bipolar disorder patients, 25 unipolar disorder patients, 136 healthy volunteers, and 14 unaffected relatives. The BIS-11A mean scores for all four groups were compared through the Games-Howell test for all possible pairwise combinations. Additionally, we compared impulsivity in bipolar and unipolar disorder patients with and without a history of suicide attempt and substance abuse disorder. RESULTS: ? Bipolar and unipolar disorder patients scored significantly higher than the healthy controls and unaffected relatives on all measures of the BIS-11A except for attentional impulsivity. On the attentional impulsivity measures there were no differences among the unaffected relatives and the bipolar and unipolar disorder groups, but all three of these groups scored higher than the healthy participant group. There was no difference in impulsivity between bipolar and unipolar disorder subjects with and without suicide attempt. However, impulsivity was higher among bipolar and unipolar disorder subjects with past substance use disorder compared to patients without such a history. CONCLUSIONS: ? Questionnaire-measured impulsivity appears to be relatively independent of mood state in bipolar and unipolar disorder patients; it remains elevated in euthymia and is higher in individuals with past substance abuse. Elevated attentional and lower non-planning impulsivity in unaffected relatives of bipolar disorder patients distinguished them from healthy participants, suggesting that increased attentional impulsivity may predispose to development of affective disorders, while reduced attentional impulsivity may be protective.

Henna E; Hatch JP; Nicoletti M; Swann AC; Zunta-Soares G; Soares JC

2013-03-01

186

The role of impulsivity, inattention and comorbid ADHD in patients with bulimia nervosa.  

UK PubMed Central (United Kingdom)

INTRODUCTION: Little is known about the contribution of impulsivity, inattention and comorbid attention deficit/hyperactivity disorder (ADHD) in the development and maintenance of bulimia nervosa (BN). In particular, their specific contribution to disordered eating symptoms and whether they have additive effects to the general psychopathological burden remains unclear. METHODS: Fifty-seven female patients seeking treatment for BN and 40 healthy controls completed diagnostic questionnaires and interviews that investigated: a) ADHD, b) impulsivity, c) eating disorders and d) general psychopathology. Attentional processes and impulsivity were assessed by a comprehensive computer-based neuropsychological battery. RESULTS: Twenty-one percent of patients with BN met the clinical cut-off for previous childhood ADHD compared to 2.5% of healthy controls. Adult ADHD according to DSM IV was also more prevalent in patients with BN, with an odds ratio of 4.2. Patients with BN and previous childhood ADHD were more impulsive and inattentive than patients with BN alone. These patients also displayed more severely disordered eating patterns and more general psychopathological symptoms compared with those without ADHD. Severity of eating disorder symptoms was better explained by inattentiveness than by either impulsivity or hyperactivity. DISCUSSION: Our data suggest an elevated rate of former childhood and current ADHD-symptoms in treatment-seeking patients with BN. Stronger impulsivity and inattention associated with more severe neuropsychological deficits and eating disorder symptoms indicate an additive risk that is clinically relevant for these patients. Thus, clinicians should identify comorbid patients who might profit from additional ADHD-specific treatments.

Seitz J; Kahraman-Lanzerath B; Legenbauer T; Sarrar L; Herpertz S; Salbach-Andrae H; Konrad K; Herpertz-Dahlmann B

2013-01-01

187

The Role of Impulsivity, Inattention and Comorbid ADHD in Patients with Bulimia Nervosa  

Science.gov (United States)

Introduction Little is known about the contribution of impulsivity, inattention and comorbid attention deficit/hyperactivity disorder (ADHD) in the development and maintenance of bulimia nervosa (BN). In particular, their specific contribution to disordered eating symptoms and whether they have additive effects to the general psychopathological burden remains unclear. Methods Fifty-seven female patients seeking treatment for BN and 40 healthy controls completed diagnostic questionnaires and interviews that investigated: a) ADHD, b) impulsivity, c) eating disorders and d) general psychopathology. Attentional processes and impulsivity were assessed by a comprehensive computer-based neuropsychological battery. Results Twenty-one percent of patients with BN met the clinical cut-off for previous childhood ADHD compared to 2.5% of healthy controls. Adult ADHD according to DSM IV was also more prevalent in patients with BN, with an odds ratio of 4.2. Patients with BN and previous childhood ADHD were more impulsive and inattentive than patients with BN alone. These patients also displayed more severely disordered eating patterns and more general psychopathological symptoms compared with those without ADHD. Severity of eating disorder symptoms was better explained by inattentiveness than by either impulsivity or hyperactivity. Discussion Our data suggest an elevated rate of former childhood and current ADHD-symptoms in treatment-seeking patients with BN. Stronger impulsivity and inattention associated with more severe neuropsychological deficits and eating disorder symptoms indicate an additive risk that is clinically relevant for these patients. Thus, clinicians should identify comorbid patients who might profit from additional ADHD-specific treatments.

Seitz, Jochen; Kahraman-Lanzerath, Berrak; Legenbauer, Tanja; Sarrar, Lea; Herpertz, Stephan; Salbach-Andrae, Harriet; Konrad, Kerstin; Herpertz-Dahlmann, Beate

2013-01-01

188

Impulse-control disorders in gilles de la tourette syndrome.  

UK PubMed Central (United Kingdom)

Impulse-control disorders (ICDs) are more common in clinic populations with Gilles de la Tourette syndrome (GTS) than in the general population. The clinical phenomenology of ICDs differ between men with GTS (who tend to be externally impulsive) and women with GTS (who tend to be internally impulsive). This article reviews the relevant literature to-date on impulsivity in GTS, with special focus on intermittent, explosive disorder, self-injurious behavior, trichotillomania, and impulsive-compulsive sexual behavior. The medical and legal community should be aware of the full spectrum of organically-based behaviors that may predispose patients with GTS to unwanted legal disciplinary action.

Wright A; Rickards H; Cavanna AE

2012-01-01

189

Dorsal/ventral parcellation of the amygdala: relevance to impulsivity and aggression.  

UK PubMed Central (United Kingdom)

Investigations into the specific association of amygdala volume, a critical aspect of the fronto-limbic emotional circuitry, and aggression have produced results broadly consistent with the 'larger is more powerful' doctrine. However, recent reports suggest that the ventral and dorsal aspects of the amygdala play functionally specific roles, respectively, in the activation and control of behavior. Therefore, parceling amygdala volume into dorsal and ventral components might prove productive in testing hypotheses regarding volumetric association to aggression, and impulsivity, a related aspect of self-control. We sought to test this hypothesis in a group of 41 psychiatric patients who received standard magnetic resonance imaging and a psychometric protocol including aggression and impulsivity measures. Whole amygdala volumes were not associated with aggression or impulsivity, but significant correlations were found when dorsal/ventral amygdalae were analyzed separately. Specifically, left and right ventral amygdala volume was positively associated with motor impulsivity, and left dorsal amygdala was negatively associated with aggression. Results are discussed in terms of an activation and control model of brain-behavior relations. Potential relevance to the continuum of amygdala hyper- to hypo-activation and aggression is discussed.

Gopal A; Clark E; Allgair A; D'Amato C; Furman M; Gansler DA; Fulwiler C

2013-01-01

190

Different subtypes of impulsivity differentiate uncontrolled eating and dietary restraint.  

UK PubMed Central (United Kingdom)

The current study explored the relationship between three subtypes of impulsivity (Reflection Impulsivity, Impulsive Choice, and Impulsive Action) and measures of uncontrolled eating (TFEQ-D) and restraint (TFEQ-R). Eighty women classified as scoring higher or lower on TFEQ-D and TFEQ-R completed the Matching Familiar Figures Test (MFFT20), Delay Discounting Task (DDT), a Go No Go task, Balloon Analogue Risk Task (BART), and the Barrett Impulsivity Scale-11 (BIS-11). To test whether these relationships were affected by enforced controls overeating, half of the participants fasted the night before and ate breakfast in the laboratory before testing and half had no such control. Women scoring higher on the TFEQ-D were significantly more impulsive on the MFFT20 and BIS-11 overall but not on DDT, Go No Go or BART. Women scoring higher on TFEQ-R were significantly less impulsive on the Go No Go task but did not differ on other measures. The eating manipulation modulated responses on the BART and BIS-11 non-planning scale depending on TFEQ-D classification. These results confirm recent data that high scores on TFEQ-D are related to impulsivity, but imply this relates more to Reflection Impulsivity rather than Impulsive Choice or Action. In contrast restrained eating was associated with better inhibitory control. Taken together, these results suggest that subtypes of impulsivity further differentiate uncontrolled eating and restraint, and suggest that a poor ability to reflect on decisions may underlie some aspects of overeating.

Leitch MA; Morgan MJ; Yeomans MR

2013-10-01

191

Impulse response in various scanning geometries for digital tomosynthesis  

Energy Technology Data Exchange (ETDEWEB)

Digital tomosynthesis (DTS) is a three-dimensional imaging technique to reconstruct a set of planes in the object. Opposed to the computed tomography (CT), however, DTS uses projection images obtained from limited angular scanning, hence there exist some artifacts such as blurs that are originated from depletion of data in the Fourier domain. The main advantages of DTS technique are shorter reconstruction time and less patient dose. There are various geometries for angular scanning available in DTS, and which is mainly dependent upon specific imaging task and applications, such as mammography, dental imaging, industrial laminography etc. In principle, DTS shares the same concept in imaging reconstruction with the conventional CT, and thus incorporates a back-projection operation. This backprojection operation determines the transfer function, which is mainly resulted from the scanning geometry, if we regard the image reconstruction as an inverse problem. Therefore, the investigation of impulse response with respect to various imaging geometries is valuable to identify artifacts associated with the scanning geometry and thus optimize the system performance. We investigate and compare the system-transfer functions (impulse-response functions) for various image acquisition schemes to acquire projection data by numerical simulation. This study may suggest fundamental limitations of a certain scanning geometry and provide the best geometry with least blur artifacts

Kim, JeeYoung; Youn, Han Bean; Cho, Min Kook; Kim, Ho Kyung [Pusan National University, Busan (Korea, Republic of)

2010-05-15

192

Impulse response in various scanning geometries for digital tomosynthesis  

International Nuclear Information System (INIS)

Digital tomosynthesis (DTS) is a three-dimensional imaging technique to reconstruct a set of planes in the object. Opposed to the computed tomography (CT), however, DTS uses projection images obtained from limited angular scanning, hence there exist some artifacts such as blurs that are originated from depletion of data in the Fourier domain. The main advantages of DTS technique are shorter reconstruction time and less patient dose. There are various geometries for angular scanning available in DTS, and which is mainly dependent upon specific imaging task and applications, such as mammography, dental imaging, industrial laminography etc. In principle, DTS shares the same concept in imaging reconstruction with the conventional CT, and thus incorporates a back-projection operation. This backprojection operation determines the transfer function, which is mainly resulted from the scanning geometry, if we regard the image reconstruction as an inverse problem. Therefore, the investigation of impulse response with respect to various imaging geometries is valuable to identify artifacts associated with the scanning geometry and thus optimize the system performance. We investigate and compare the system-transfer functions (impulse-response functions) for various image acquisition schemes to acquire projection data by numerical simulation. This study may suggest fundamental limitations of a certain scanning geometry and provide the best geometry with least blur artifacts

2010-01-01

193

Impulse control disorders in women with eating disorders.  

Science.gov (United States)

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

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

2007-10-24

194

LMFBR core flowering response to an impulse load  

International Nuclear Information System (INIS)

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

1993-01-01

195

Filament-driven impulsive Raman spectroscopy.  

UK PubMed Central (United Kingdom)

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

Odhner JH; McCole ET; Levis RJ

2011-11-01

196

[Impulse control behaviors associated with antiparkinsonian medications].  

UK PubMed Central (United Kingdom)

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

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

2013-05-01

197

Elegant impulser developed for flat beam injection  

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 [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.

Wilson, M. J., LLNL

1998-05-26

198

FEM Analysis of Turgo Impulse Turbine Blade  

Directory of Open Access Journals (Sweden)

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

Sourabh KHURANA; Varun GOEL; Anoop KUMAR

2013-01-01

199

Impulse noise generated by starter pistols.  

UK PubMed Central (United Kingdom)

OBJECTIVE: This study describes signals generated by .22 and .32 caliber starter pistols in the context of noise-induced hearing loss risk for sports officials and athletes. DESIGN: Acoustic comparison of impulses generated from typical .22 and .32 caliber starter pistols firing blanks were made to impulses generated from comparable firearms firing both blanks and live rounds. Acoustic characteristics are described in terms of directionality and distance from the shooter in a simulated outdoor running track. Metrics include peak sound pressure levels (SPL), A-weighted equivalent 8-hour level (L(eqA8)), and maximum permissible number of individual shots, or maximum permissible exposures (MPE) for the unprotected ear. RESULTS: Starter pistols produce peak SPLs above 140 dB. The numbers of MPEs are as few as five for the .22-caliber starter pistol, and somewhat higher (? 25) for the .32-caliber pistol. CONCLUSION: The impulsive sounds produced by starter pistols correspond to MPE numbers that are unacceptably small for unprotected officials and others in the immediate vicinity of the shooter. At the distances included in this study, the risk to athletes appears to be low (when referencing exposure criteria for adults), but the sound associated with the starter pistol will contribute to the athlete's overall noise exposure.

Meinke DK; Finan DS; Soendergaard J; Flamme GA; Murphy WJ; Lankford JE; Stewart M

2013-02-01

200

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

UK PubMed Central (United Kingdom)

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.

Oliveira AS; Silva PB; Lund ME; Kersting UG; Farina D

2013-01-01

 
 
 
 
201

Single doses of THC and cocaine decrease proficiency of impulse control in heavy cannabis users.  

UK PubMed Central (United Kingdom)

BACKGROUND AND PURPOSE: Cannabis is the most popular drug used in the European Union, closely followed by cocaine. Whereas cannabis has been shown to impair neurocognitive function in occasional cannabis users, such impairments appear less prominent in heavy users, possibly as a result of tolerance. The present study was designed to assess whether the impairing effects of THC in heavy cannabis users would present in a wide range of neuropsychological functions or selectively pertain to specific performance domains. A second aim was to assess the acute effects of cocaine on neurocognitive functions of heavy cannabis users. EXPERIMENTAL APPROACH: Heavy cannabis users, who had a history of cocaine use (N=61), participated in a double-blind, placebo controlled, 3-way crossover study. Subjects received single doses of cocaine HCl 300 mg, cannabis (THC 300 ?g/kg) and placebo and completed a number of tests measuring impulse control and psychomotor function. KEY RESULTS: Results showed that single doses of cannabis impaired psychomotor function and increased response errors during impulsivity tasks. Single doses of cocaine improved psychomotor function and decreased response time in impulsivity tasks at a cost of making more errors. CONCLUSIONS AND IMPLICATIONS: Heavy cannabis users display impairments in a broad range of neuropsychological domains during THC intoxication. Impairments observed in psychomotor tasks, but not in impulsivity tasks, appeared smaller in magnitude as compared to those previously reported in occasional cannabis users. Heavy cannabis users were sensitive to the stimulatory and inhibitory effects of cocaine on psychomotor function and impulsivity respectively. The?reduction in proficiency in impulse control may put drug users at increased risk of repeated drug use.

van Wel JH; Kuypers KP; Theunissen EL; Toennes SW; Spronk DB; Verkes RJ; Ramaekers JG

2013-09-01

202

Impulsivity in adult ADHD patients with and without cocaine dependence.  

UK PubMed Central (United Kingdom)

BACKGROUND: Attention deficit hyperactivity disorder (ADHD) is present in about a quarter of patients with a substance use disorder (SUD) and impulsivity is a key feature of both disorders. However, very little is known about differences in impulse control and other cognitive functions between ADHD patients with and without SUD. METHODS: In adult male medication-naïve ADHD patients with and without comorbid cocaine dependence and healthy controls (matched on gender, age and IQ), we measured motor impulsivity (stop signal task), cognitive impulsivity (delay discounting task), divided attention (trail making test), interference (Stroop task), working memory (n-back task), and time reproduction (time reproduction task). Additionally, self-reported ADHD symptoms (using the ADHD Symptom Rating Scale; ASRS) and self-reported impulsivity (Barratt Impulsivity Scale; BIS) were assessed. RESULTS: Significantly higher levels of motor and cognitive impulsivity were found in ADHD patients with comorbid cocaine dependence compared to ADHD patients without cocaine dependence and controls, and both measures of impulsivity were highly correlated. No significant group differences were found on other cognitive measures. With regard to the self-report measures, only BIS attention subscores differed significantly between ADHD patients with and without cocaine dependence. ASRS and BIS scores were not significantly correlated. CONCLUSION: This is the first study showing that ADHD patients with cocaine dependence are a distinctly more impulsive subpopulation compared to ADHD patients without cocaine dependence on objective measures of impulsivity. These findings are relevant to optimize psycho-education and treatment of ADHD patients with comorbid SUD.

Crunelle CL; Veltman DJ; van Emmerik-van Oortmerssen K; Booij J; van den Brink W

2013-04-01

203

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

Directory of Open Access Journals (Sweden)

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

T. R. Robinson

0000-01-01

204

Impulsive choice and response in dopamine agonist-related impulse control behaviors.  

UK PubMed Central (United Kingdom)

RATIONALE: Dopaminergic medication-related impulse control disorders (ICDs) such as pathological gambling and compulsive shopping have been reported in Parkinson's disease (PD). HYPOTHESIS: We hypothesized that dopamine agonists (DAs) would be associated with greater impulsive choice or greater discounting of delayed rewards in PD patients with ICDs (PDI). METHODS: Fourteen PDI patients, 14 PD controls without ICDs, and 16 medication-free matched normal controls were tested on the Experiential Discounting Task (EDT), a feedback-based intertemporal choice task, spatial working memory, and attentional set shifting. The EDT was used to assess choice impulsivity (hyperbolic K value), reaction time (RT), and decision conflict RT (the RT difference between high conflict and low conflict choices). PDI patients and PD controls were tested on and off DA. RESULTS: On the EDT, there was a group by medication interaction effect [F(1,26) = 5.62; p = 0.03] with pairwise analyses demonstrating that DA status was associated with increased impulsive choice in PDI patients (p = 0.02) but not in PD controls (p = 0.37). PDI patients also had faster RT compared to PD controls [F(1,26) = 7.51, p = 0.01]. DA status was associated with shorter RT [F(3,24) = 8.39, p = 0.001] and decision conflict RT [F(1,26) = 6.16, p = 0.02] in PDI patients but not in PD controls. There were no correlations between different measures of impulsivity. PDI patients on DA had greater spatial working memory impairments compared to PD controls on DA (t = 2.13, df = 26, p = 0.04). CONCLUSION: Greater impulsive choice, faster RT, faster decision conflict RT, and executive dysfunction may contribute to ICDs in PD.

Voon V; Reynolds B; Brezing C; Gallea C; Skaljic M; Ekanayake V; Fernandez H; Potenza MN; Dolan RJ; Hallett M

2010-01-01

205

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

206

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

UK PubMed Central (United Kingdom)

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.

Leeman RF; Potenza MN

2011-04-01

207

Specifying the impulsivity of female inmates with borderline personality disorder.  

UK PubMed Central (United Kingdom)

Impulsivity is regarded as a core feature of borderline personality disorder (BPD; M. C. Zanarini, J. G. Gunderson, & F. R. Frankenburg, 1989) despite lack of evidence from laboratory research (D. M. Dougherty, J. M Bjork, H. C. G. Huckabee, F. G. Moeller, & A. C. Swann, 1999). This study examined impulsivity in incarcerated women with BPD using a passive avoidance task (J. P. Newman & W. A. Schmitt, 1998) and the Impulsiveness-Monotony Avoidance-Detachment inventory (IMD; D. Schalling, 1978). As predicted, incarcerated women diagnosed with BPD committed more passive avoidance errors and reported more impulsivity on the IMD than controls. These findings identify disinhibition as a potentially important component of the impulsivity that characterizes BPD. Specifying the impulsive behavior identified with BPD may contribute to the effective assessment and management of the disorder.

Hochhausen NM; Lorenz AR; Newman JP

2002-08-01

208

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

UK PubMed Central (United Kingdom)

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

Blonigen DM; Timko C; Moos RH

2013-01-01

209

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; Gheysar Maleki

2012-01-01

210

Increased reflection impulsivity in patients with ephedrone-induced Parkinsonism.  

UK PubMed Central (United Kingdom)

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

Djamshidian A; Sanotsky Y; Matviyenko Y; O'Sullivan SS; Sharman S; Selikhova M; Fedoryshyn L; Filts Y; Bearn J; Lees AJ; Averbeck BB

2013-04-01

211

Energetic electrons in impulsive solar flares  

International Nuclear Information System (INIS)

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

1984-01-01

212

Energetic electrons in impulsive solar flares  

Energy Technology Data Exchange (ETDEWEB)

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

Batchelor, D.A.

1984-05-01

213

Inhibitory Control Contributes to "Motor"- but not "Cognitive"- Impulsivity.  

UK PubMed Central (United Kingdom)

Literature on impulsivity regularly claims inhibitory control deficits underlie impulsive behavior. The current study investigated whether taxing inhibitory control will increase reflection (decision making under conditions of uncertainty), temporal (delay of gratification), and motor impulsivity (behavioral disinhibition). Inhibitory control was challenged, via a random letter generation task presented during responding to three impulsivity measures: the Information Sampling Task (IST), Single Key Impulsivity Paradigm, and the Stop Signal Task (SST). Participants (n = 33) were assigned to the inhibitory control challenging (experimental) condition, or to a control condition in which inhibitory control was not challenged. The SST was affected by the inhibitory control challenge: participants in the experimental condition displayed increased motor impulsivity, evidenced in longer stop signal reaction times (SSRTs) compared to the control group. The manipulation did not affect reflection- or temporal- impulsivity measures. These data support the suggestion that the mechanisms underlying the motor subtype of impulsivity are dissociable from the temporal and reflection subtypes, and that engagement of inhibitory control is not necessary to prevent impulsive decision making.

Caswell AJ; Morgan MJ; Duka T

2013-01-01

214

Impulsive waves in electrovac direct product spacetimes with ?  

International Nuclear Information System (INIS)

A complete family of non-expanding impulsive waves in spacetimes which are the direct product of two 2-spaces of constant curvature is presented. In addition to previously investigated impulses in Minkowski, (anti-)Nariai and Bertotti-Robinson universes, a new explicit class of impulsive waves which propagate in the exceptional electrovac Plebanski-Hacyan spacetimes with a cosmological constant ? is constructed. In particular, pure gravitational waves generated by null particles with an arbitrary multipole structure are described. The metrics are impulsive members of a more general family of the Kundt spacetimes of type II. The well-known pp-waves are recovered for ? = 0.

2002-10-21

215

Dynamical mechanical systems under random impulses  

CERN Multimedia

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

Iwankiewicz, R

1995-01-01

216

Impulsive stabilization of linear delay differential equations  

CERN Document Server

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

Berezansky, L; Berezansky, L; Braverman, E

1995-01-01

217

[Impulse control disorders and Parkinson's disease  

UK PubMed Central (United Kingdom)

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

Burkhard PR; Catalano-Chiuvé S; Gronchi-Perrin A; Berney A; Vingerhoets FJ; Lüscher C

2008-05-01

218

Impulsivity-related personality traits and adolescent alcohol use: a meta-analytic review.  

UK PubMed Central (United Kingdom)

Heightened impulsivity has been identified as a risk marker for excessive and problematic alcohol use, particularly during adolescence when impulsive behaviour is elevated and alcohol use is often initiated. Recent advances in personality theory indicate that impulsivity comprises several discrete traits which may influence alcohol use through different pathways. This review used meta-analysis to assess the degree to which the impulsivity-related traits of lack of premeditation, lack of perseverance, sensation seeking, negative urgency, positive urgency, and reward sensitivity are associated with alcohol consumption and problematic alcohol use in adolescent samples. All traits were positively associated with both alcohol outcomes. Sensation seeking and positive urgency showed the largest associations with alcohol consumption. Positive and negative urgency showed the largest associations with problematic alcohol use, although this was limited to older adolescent samples. A number of demographic and methodological variables were assessed as potential moderators of these associations. Results indicate that excessive alcohol consumption during adolescence may be driven in part by the desire to seek novel and exciting experiences. Problematic use, specifically amongst older adolescents, may be a consequence of a tendency to act rashly when in a heightened positive or negative mood.

Stautz K; Cooper A

2013-06-01

219

Overexpression of ?3/?5/?4 nicotinic receptor subunits modifies impulsive-like behavior.  

UK PubMed Central (United Kingdom)

Recent studies have revealed that sequence variants in genes encoding the ?3/?5/?4 nicotinic acetylcholine receptor subunits are associated with nicotine dependence. In this study, we evaluated two specific aspects of executive functioning related to drug addiction (impulsivity and working memory) in transgenic mice over expressing ?3/?5/?4 nicotinic receptor subunits. Impulsivity and working memory were evaluated in an operant delayed alternation task, where mice must inhibit responding between 2 and 8s in order to receive food reinforcement. Working memory was also evaluated in a spontaneous alternation task in an open field. Transgenic mice showed less impulsive-like behavior than wild-type controls, and this behavioral phenotype was related to the number of copies of the transgene. Thus, transgenic Line 22 (16-28 copies) showed a more pronounced phenotype than Line 30 (4-5 copies). Overexpression of these subunits in Line 22 reduced spontaneous alternation behavior suggesting deficits in working memory processing in this particular paradigm. These results reveal the involvement of ?3/?5/?4 nicotinic receptor subunits in working memory and impulsivity, two behavioral traits directly related to the vulnerability to develop nicotine dependence.

Viñals X; Molas S; Gallego X; Fernández-Montes RD; Robledo P; Dierssen M; Maldonado R

2012-05-01

220

The five-factor model of impulsivity-like traits and emotional lability in aggressive behavior.  

UK PubMed Central (United Kingdom)

Factors that increase automatic psychological processes may result in impulsive action and, consequently, aggressive behavior. The current cross-sectional study examined the association between the five-factor model of impulsivity-like traits (negative urgency, positive urgency, premeditation, perseverance, and sensation seeking), emotional lability, and physically aggressive behaviors among college students (n = 481) in a negative binomial hurdle model. In the logistic portion of the model, emotional lability was related to a higher likelihood of engaging in aggressive acts in the past 6 months. The association between emotional lability and the likelihood of aggressive behavior was moderated by two impulsivity-like traits: negative urgency and positive urgency. Specifically, emotional lability was related to engaging in aggressive acts among those with high negative urgency, and among those with low positive urgency. In the count portion of the model, emotional lability was uniquely related to the number of aggressive acts in the past 6 months. Our results indicate that emotional lability and facets of impulsivity interactively relate to engagement in aggressive behavior, suggesting that these variables be integrated into models of aggression.

Dvorak RD; Pearson MR; Kuvaas NJ

2013-05-01

 
 
 
 
221

Concrete structures under impact and impulsive loading  

International Nuclear Information System (INIS)

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

1982-06-04

222

Shock Dissipation in Magnetically Dominated Impulsive Flows  

CERN Multimedia

We have revisited the issue of shock dissipation and emission and its implications for the internal shock model of the prompt GRB emission and studied it in the context of impulsive Poynting-dominated flows. Our results show that unless the magnetization of GRB jets is extremely high, \\sigma > 100 in the prompt emission zone, the magnetic model may still be compatible with the observations. The main effect of reduced dissipation efficiency is merely an increase in the size of the dissipation zone and even for highly magnetised GRB jets this size may remain below the external shock radius, provided the central engine can emit magnetic shells on the time scale well below the typical observed variability scale of one second. Our analytical and numerical results suggest that magnetic shells begin strongly interact with each other well before they reach the coasting radius. As the result, the impulsive jet in the dissipation zone is best described not as a collection of shells but as a continuous highly magnetised...

Komissarov, S S

2012-01-01

223

An improved radial impulse turbine for OWC  

Energy Technology Data Exchange (ETDEWEB)

Traditionally, wells turbines have been widely used in OWC plants. However, an alternative has been studied over recent years: a self-rectifying turbine known as an impulse turbine. We are interested in the radial version of the impulse turbine, which was initially proposed by M. McCormick. Previous research was carried out using CFD (FLUENT {sup registered}), which aimed to improve knowledge of the local flow behavior and the prediction of the performance for this kind of turbine. This previous work was developed with a geometry taken from the literature, but now our goal is to develop a new geometry design with a better performance. To achieve this, we have redesigned the blade and vane profiles and improved the interaction between them by means of a new relation between their setting angles. Under sinusoidal flow conditions the new design improves the turbine efficiency by up to 5% more than the geometry proposed by Professor Setoguchi, in 2002. In this paper, the design criteria we have used is described, and the flow behavior and the performance of this new design are compared with the previous one. (author)

Pereiras, Bruno; Castro, Francisco; Rodriguez, Miguel A. [Energy Engineering and Fluid Mechanics Department, University of Valladolid, Paseo del cauce 59, 47011, Valladolid (Spain); Marjani, Abdelatif el [Labo. de Turbomachines, Ecole Mohammadia d' Ingenieurs (EMI), University of Mohammed V Agdal. Av Ibn Sina, B.P. 765 Agdal Rabat (Morocco)

2011-05-15

224

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

UK PubMed Central (United Kingdom)

Although traditionally obsessive-compulsive disorder (OCD) and impulse control disorders (ICD) have represented opposing ends of a continuum, recent research has demonstrated a frequent co-occurrence of impulsive and compulsive behaviours, which may contribute to a worse clinical picture of some psychiatric disorders. We hypothesize that individuals with 'impulsive' OCD as characterized by poor insight, low resistance, and reduced control towards their compulsions will have a deteriorative course, greater severity of hoarding and/or symmetry/ordering symptoms, and comorbid ICD and/or substance use disorders (SUD). The sample consisted of 869 individuals with a minimum score of 16 on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). Of these, 65 had poor insight, low resistance, and reduced control towards compulsions ('poor IRC') and 444 had preserved insight, greater resistance and better control over compulsions ('good IRC'). These two groups were compared on a number of clinical and demographic variables. Individuals with poor IRC were significantly more likely to have a deteriorative course (p < 0.001), longer duration of obsessions (p = 0.017), greater severity of symmetry/ordering (p < 0.001), contamination/cleaning (p < 0.001) and hoarding (p = 0.002) symptoms, and comorbid intermittent explosive disorder (p = 0.026), trichotillomania (p = 0.014) and compulsive buying (p = 0.040). Regression analysis revealed that duration of obsessions (p = 0.037) and hoarding severity (p = 0.005) were significant predictors of poor IRC. In the absence of specific measures for impulsivity in OCD, the study highlights the utility of simple measures such as insight, resistance and control over compulsions as a phenotypic marker of a subgroup of OCD with impulsive features demonstrating poor clinical outcome.

Kashyap H; Fontenelle LF; Miguel EC; Ferrão YA; Torres AR; Shavitt RG; Ferreira-Garcia R; do Rosário MC; Yücel M

2012-09-01

225

Few body impulse and fixed scatterer approximations for high energy scattering  

International Nuclear Information System (INIS)

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

2006-05-29

226

Research in impulse joining of self pierce riveting  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Results are shown in impulse joining of aluminium sheets with self-pierce-riveting. Two institutes are testing impulse-riveting with different setting velocities of the punch - up to 10 m/s by using pneumatic cylinders and about 100 m/s by using a propellant charge. One aim focus consists in rivetin...

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

227

Oscillation of solutions to impulsive dynamic equations on time scales  

Directory of Open Access Journals (Sweden)

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

Qiaoluan Li; Fang Guo

2009-01-01

228

The conduction of the cardiac impulse 1951-1986.  

UK PubMed Central (United Kingdom)

The study of the propagation of the cardiac impulse during the last 35 years is reviewed with special attention to the contributions of Silvio Weidmann and his colleagues. Special emphasis is placed on the need to prove that the cardiac impulse is transmitted electrically, even when it is conducted under very abnormal conditions.

Cranefield PF

1987-10-01

229

EFFECT OF POLARITY ON THE IMPULSE BREAKDOWN OF SF6  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effect of polarity on the impulse breakdown of SF6 and the influence which a thin dielectric coating has on the impulse breakdown for both polarities was studied in the pressure range of 1-7 bara in a coaxial cylinder electrode configuration.

Antonios Vlastós, E.

230

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; Xinzhi Liu

1991-01-01

231

Impulsivity and rapid decision-making for reward.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Impulsivity is a feature of many brain disorders. Although often defined as the predisposition to act with an inadequate degree of deliberation, forethought, or control, it has proven difficult to measure. This may in part be due to the fact that it is a multifaceted construct, with impulsive decisi...

232

Virtual Shopping and Impulse Purchasing Strengths and Weaknesses in Pakistan  

Directory of Open Access Journals (Sweden)

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

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

2011-01-01

233

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

DEFF Research Database (Denmark)

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

Callesen, Mette Buhl; Scheel-Krüger, JØrgen

2013-01-01

234

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.

2009-10-30

235

Force and impulse from an Aharonov-Bohm flux line  

CERN Document Server

We calculate the force and impulse operators for a charged particle in the field of an Aharonov-Bohm flux line. The force operator is formally the Lorentz force, with the magnetic field operator modified to include quantum corrections due to anomolous commutation relations. Expectation values for stationary states are calculated. Nonstationary states are treated by integrating the force operator in time to obtain the impulse operator. Expectation values of the impulse are calculated for slow wavepackets (which spread faster than they move) and for fast wavepackets (which spread only negligibly before their closest approach to the flux line). We give two derivations of the force and impulse operators, the first a simple derivation based on formal arguments, and the second a rigorous calculation of wavepacket expectation values. We also show that the same expressions for the force and impulse are obtained if the flux line is enclosed in an impenetrable cylinder,or distributed uniformly over a flux cylinder, in ...

Keating, J P

2001-01-01

236

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

International Nuclear Information System (INIS)

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

1997-01-01

237

Associations between trait impulsivity and prepotent response inhibition.  

Science.gov (United States)

This study addresses the relationship between trait impulsivity and inhibitory control, two features known to be impaired in a number of psychiatric conditions. While impulsivity is often measured using psychometric self-report questionnaires, the inhibition of inappropriate, impulsive motor responses is typically measured using experimental laboratory tasks. It remains unclear, however, whether psychometrically assessed impulsivity and experimentally operationalized inhibitory performance are related to each other. Therefore, we investigated the relationship between these two traits in a large sample using correlative and latent variable analysis. A total of 504 healthy individuals completed the Barratt Impulsiveness Scale (BIS-11) and a battery of four prepotent response inhibition paradigms: the antisaccade, Stroop, stop-signal, and go/no-go tasks. We found significant associations of BIS impulsivity with commission errors on the go/no-go task and directional errors on the antisaccade task, over and above effects of age, gender, and intelligence. Latent variable analysis (a) supported the idea that all four inhibitory measures load on the same underlying construct termed "prepotent response inhibition" and (b) revealed that 12% of variance of the prepotent response inhibition construct could be explained by BIS impulsivity. Overall, the magnitude of associations observed was small, indicating that while a portion of variance in prepotent response inhibition can be explained by psychometric trait impulsivity, the majority of variance remains unexplained. Thus, these findings suggest that prepotent response inhibition paradigms can account for psychometric trait impulsivity only to a limited extent. Implications for studies of patient populations with symptoms of impulsivity are discussed. PMID:22888795

Aichert, Désirée S; Wöstmann, Nicola M; Costa, Anna; Macare, Christine; Wenig, Johanna R; Möller, Hans-Jürgen; Rubia, Katya; Ettinger, Ulrich

2012-08-14

238

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present work is devoted to the study of stability of the zero solution to linear impulsive differential-difference equations with variable impulsive perturbations. With the aid of piecewise continuous auxiliary functions, which are generalizations of the classical Lyapunov's functions, sufficien...

D. D. Bainov; I. M. Stamova; A. S. Vatsala

239

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

UK PubMed Central (United Kingdom)

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.

Li C; Wu S; Feng GG; Liao X

2011-02-01

240

The functional anatomy of impulse control disorders.  

UK PubMed Central (United Kingdom)

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

Probst CC; van Eimeren T

2013-10-01

 
 
 
 
241

The functional anatomy of impulse control disorders.  

Science.gov (United States)

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

Probst, Catharina C; van Eimeren, Thilo

2013-10-01

242

Compton scattering beyond the impulse approximation  

CERN Multimedia

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

243

Magnetospheric plasma drift during a sudden impulse  

Energy Technology Data Exchange (ETDEWEB)

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

Baumjohann, W.; Bauer, O.H.; Haerendel, G.; Junginger, H.; Amata, E.

1983-11-01

244

Superconductivity switch with impulse current triggering  

International Nuclear Information System (INIS)

[en] Supplying reactive power by superconducting storage systems may have considerable advantages. The behaviour and parameters of the switching device, opening and closing the storage circuit are studied. Approximative mathematical solutions are checked against measured results. The influence of the impulse capacitor is studied and hints to design the triggering circuits are given. (orig.)[de] Die Bereitstellung der fuer die Erregung grosser Magnete noetigen Energie mit supraleitenden Energiespeichersystemen kann von Vorteil sein. Das Verhalten und die Parameter des Schaltgliedes, das den supraleitenden Speicherkreis schliesst und oeffnet, werden untersucht. Mathematische Naeherungsloesungen werden mit gemessenen Resultaten auf ihre Eignung geprueft. Der Einfluss des Stosskondensators wird untersucht und Hinweise fuer Auslegung der Stosskreise werden angegeben. (orig.)

1975-01-01

245

Investigation of gas discharge impulse image intensifiers  

CERN Multimedia

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

Gushchin, E M; Timofeev, M K

1999-01-01

246

Impulsive ion acceleration in earth's outer magnetosphere  

International Nuclear Information System (INIS)

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

1985-01-01

247

Energetic electrons in impulsive solar flares  

International Nuclear Information System (INIS)

Impulsive bursts of hard X rays and microwaves are observed during most solar flares, and both emissions can be attributed to a common distribution of source electrons with energies from approximately 10 keV to several hundred keV. A detailed account of the evolution of the electron distribution is crucial to a complete description of the energy release process in flares. In this dissertation, a new analysis is made of a thermal flare model proposed by Brown, Melrose, and Spicer (1979) and Smith and Lilliequist (1979). Brown, Melrose, and Spicer (1979) and Smith and Brown (1980) argued that the source assumed in this model would not explain the simultaneous impulsive microwave emission. In contrast, the new results presented here show that this model leads to the development of a quasi-Maxwellian distribution of electrons that explains both the hard x-ray and microwave emissions. This implies that the source sizes can be determined from observations of the optically-thick portions of microwave spectra and the temperatures obtained from associated hard x-ray observations. The x-ray observations were obtained with the Hard X-ray Burst Spectrometer on board the Solar Maximum Mission spacecraft, and the microwave observations were obtained from the Bern Radio Observatory in Switzerland. The results of this investigation are in good agreement with the model and are not explained by any other flare models which have been considered. A re-evaluation of contradictory reports regarding the visibility of individual starspots led to the conclusion that large spots would indeed be observable with equipment of high precision. A comprehensive physical and evolutional model for the cumulative spectroscopic and photometric behavior of AR Lac was constructed by augmentation of other models and incorporation of the results of the present investigation

1984-01-01

248

Energetic electrons in impulsive solar flares  

Energy Technology Data Exchange (ETDEWEB)

Impulsive bursts of hard X rays and microwaves are observed during most solar flares, and both emissions can be attributed to a common distribution of source electrons with energies from approximately 10 keV to several hundred keV. A detailed account of the evolution of the electron distribution is crucial to a complete description of the energy release process in flares. In this dissertation, a new analysis is made of a thermal flare model proposed by Brown, Melrose, and Spicer (1979) and Smith and Lilliequist (1979). Brown, Melrose, and Spicer (1979) and Smith and Brown (1980) argued that the source assumed in this model would not explain the simultaneous impulsive microwave emission. In contrast, the new results presented here show that this model leads to the development of a quasi-Maxwellian distribution of electrons that explains both the hard x-ray and microwave emissions. This implies that the source sizes can be determined from observations of the optically-thick portions of microwave spectra and the temperatures obtained from associated hard x-ray observations. The x-ray observations were obtained with the Hard X-ray Burst Spectrometer on board the Solar Maximum Mission spacecraft, and the microwave observations were obtained from the Bern Radio Observatory in Switzerland. The results of this investigation are in good agreement with the model and are not explained by any other flare models which have been considered. A re-evaluation of contradictory reports regarding the visibility of individual starspots led to the conclusion that large spots would indeed be observable with equipment of high precision. A comprehensive physical and evolutional model for the cumulative spectroscopic and photometric behavior of AR Lac was constructed by augmentation of other models and incorporation of the results of the present investigation.

Batchelor, D.A.

1984-01-01

249

The role of negative emotionality and impulsivity in depressive/anxiety disorders and alcohol dependence.  

UK PubMed Central (United Kingdom)

BACKGROUND: Much is still unclear about the role of personality in the structure of common psychiatric disorders such as depressive/anxiety disorders and alcohol dependence. This study will therefore examine whether various traits of negative emotionality and impulsivity showed shared or specific associations with these disorders. Method Cross-sectional data were used from the Netherlands Study of Depression and Anxiety (NESDA), including individuals with no DSM-IV psychiatric disorder (n = 460), depressive/anxiety disorder only (i.e. depressive and/or anxiety disorder; n = 1398), alcohol dependence only (n = 32) and co-morbid depressive/anxiety disorder plus alcohol dependence (n = 358). Aspects of negative emotionality were neuroticism, hopelessness, rumination, worry and anxiety sensitivity, whereas aspects of impulsivity included disinhibition, thrill/adventure seeking, experience seeking and boredom susceptibility. RESULTS: Aspects of negative emotionality formed a homogeneous dimension, which was unrelated to the more heterogeneous construct of impulsivity. Although all aspects of negative emotionality were associated with alcohol dependence only, associations were much stronger for depressive/anxiety disorder only and co-morbid depressive/anxiety disorder with alcohol dependence. The results for impulsivity traits were less profound and more variable, with disinhibition and boredom susceptibility showing modest associations with both depressive/anxiety disorder and alcohol dependence, whereas low thrill/adventure seeking and high disinhibition were more strongly related with the first and the latter, respectively. CONCLUSIONS: Our results suggest that depressive/anxiety disorder and alcohol dependence result from shared as well as specific aetiological pathways as they showed the same associations with all aspects of negative emotionality, disinhibition and boredom susceptibility as well as specific associations with thrill/adventure seeking and disinhibition.

Boschloo L; Vogelzangs N; van den Brink W; Smit JH; Beekman AT; Penninx BW

2013-06-01

250

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

UK PubMed Central (United Kingdom)

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

Bayard S; Raffard S; Gely-Nargeot MC

2011-12-01

251

Objectively-measured impulsivity and attention-deficit/hyperactivity disorder (ADHD): testing competing predictions from the working memory and behavioral inhibition models of ADHD.  

UK PubMed Central (United Kingdom)

Impulsivity is a hallmark of two of the three DSM-IV ADHD subtypes and is associated with myriad adverse outcomes. Limited research, however, is available concerning the mechanisms and processes that contribute to impulsive responding by children with ADHD. The current study tested predictions from two competing models of ADHD-working memory (WM) and behavioral inhibition (BI)-to examine the extent to which ADHD-related impulsive responding was attributable to model-specific mechanisms and processes. Children with ADHD (n?=?21) and typically developing children (n?=?20) completed laboratory tasks that provided WM (domain-general central executive [CE], phonological/visuospatial storage/rehearsal) and BI indices (stop-signal reaction time [SSRT], stop-signal delay, mean reaction time). These indices were examined as potential mediators of ADHD-related impulsive responding on two objective and diverse laboratory tasks used commonly to assess impulsive responding (CPT: continuous performance test; VMTS: visual match-to-sample). Bias-corrected, bootstrapped mediation analyses revealed that CE processes significantly attenuated between-group impulsivity differences, such that the initial large-magnitude impulsivity differences were no longer significant on either task after accounting for ADHD-related CE deficits. In contrast, SSRT partially mediated ADHD-related impulsive responding on the CPT but not VMTS. This partial attenuation was no longer significant after accounting for shared variance between CE and SSRT; CE continued to attenuate the ADHD-impulsivity relationship after accounting for SSRT. These findings add to the growing literature implicating CE deficits in core ADHD behavioral and functional impairments, and suggest that cognitive interventions targeting CE rather than storage/rehearsal or BI processes may hold greater promise for alleviating ADHD-related impairments.

Raiker JS; Rapport MD; Kofler MJ; Sarver DE

2012-07-01

252

Objectively-measured impulsivity and attention-deficit/hyperactivity disorder (ADHD): testing competing predictions from the working memory and behavioral inhibition models of ADHD.  

Science.gov (United States)

Impulsivity is a hallmark of two of the three DSM-IV ADHD subtypes and is associated with myriad adverse outcomes. Limited research, however, is available concerning the mechanisms and processes that contribute to impulsive responding by children with ADHD. The current study tested predictions from two competing models of ADHD-working memory (WM) and behavioral inhibition (BI)-to examine the extent to which ADHD-related impulsive responding was attributable to model-specific mechanisms and processes. Children with ADHD (n?=?21) and typically developing children (n?=?20) completed laboratory tasks that provided WM (domain-general central executive [CE], phonological/visuospatial storage/rehearsal) and BI indices (stop-signal reaction time [SSRT], stop-signal delay, mean reaction time). These indices were examined as potential mediators of ADHD-related impulsive responding on two objective and diverse laboratory tasks used commonly to assess impulsive responding (CPT: continuous performance test; VMTS: visual match-to-sample). Bias-corrected, bootstrapped mediation analyses revealed that CE processes significantly attenuated between-group impulsivity differences, such that the initial large-magnitude impulsivity differences were no longer significant on either task after accounting for ADHD-related CE deficits. In contrast, SSRT partially mediated ADHD-related impulsive responding on the CPT but not VMTS. This partial attenuation was no longer significant after accounting for shared variance between CE and SSRT; CE continued to attenuate the ADHD-impulsivity relationship after accounting for SSRT. These findings add to the growing literature implicating CE deficits in core ADHD behavioral and functional impairments, and suggest that cognitive interventions targeting CE rather than storage/rehearsal or BI processes may hold greater promise for alleviating ADHD-related impairments. PMID:22271141

Raiker, Joseph S; Rapport, Mark D; Kofler, Michael J; Sarver, Dustin E

2012-07-01

253

A spline-based approach for computing spatial impulse responses.  

UK PubMed Central (United Kingdom)

Computer simulations are an essential tool for the design of phased-array ultrasonic imaging systems. FIELD II, which determines the two-way temporal response of a transducer at a point in space, is the current de facto standard for ultrasound simulation tools. However, the need often arises to obtain two-way spatial responses at a single point in time, a set of dimensions for which FIELD II is not well optimized. This paper describes an analytical approach for computing the two-way, far-field, spatial impulse response from rectangular transducer elements under arbitrary excitation. The described approach determines the response as the sum of polynomial functions, making computational implementation quite straightforward. The proposed algorithm, named DELFI, was implemented as a C routine under Matlab and results were compared to those obtained under similar conditions from the well-established FIELD II program. Under the specific conditions tested here, the proposed algorithm was approximately 142 times faster than FIELD II for computing spatial sensitivity functions with similar amounts of error. For temporal sensitivity functions with similar amounts of error, the proposed algorithm was about 1.7 times slower than FIELD II using rectangular elements and 19.2 times faster than FIELD II using triangular elements. DELFI is shown to be an attractive complement to FIELD II, especially when spatial responses are needed at a specific point in time.

Ellis MA; Guenther D; Walker WF

2007-05-01

254

A spline-based approach for computing spatial impulse responses.  

Science.gov (United States)

Computer simulations are an essential tool for the design of phased-array ultrasonic imaging systems. FIELD II, which determines the two-way temporal response of a transducer at a point in space, is the current de facto standard for ultrasound simulation tools. However, the need often arises to obtain two-way spatial responses at a single point in time, a set of dimensions for which FIELD II is not well optimized. This paper describes an analytical approach for computing the two-way, far-field, spatial impulse response from rectangular transducer elements under arbitrary excitation. The described approach determines the response as the sum of polynomial functions, making computational implementation quite straightforward. The proposed algorithm, named DELFI, was implemented as a C routine under Matlab and results were compared to those obtained under similar conditions from the well-established FIELD II program. Under the specific conditions tested here, the proposed algorithm was approximately 142 times faster than FIELD II for computing spatial sensitivity functions with similar amounts of error. For temporal sensitivity functions with similar amounts of error, the proposed algorithm was about 1.7 times slower than FIELD II using rectangular elements and 19.2 times faster than FIELD II using triangular elements. DELFI is shown to be an attractive complement to FIELD II, especially when spatial responses are needed at a specific point in time. PMID:17523569

Ellis, Michael A; Guenther, Drake; Walker, William F

2007-05-01

255

Links between self-reported and laboratory behavioral impulsivity.  

UK PubMed Central (United Kingdom)

A major problem in the research considering impulsivity is the lack of mutual understanding on how to measure and define impulsivity. Our study examined the relationship between self-reported impulsivity, behavioral excitatory and inhibitory processes and time perception. Impulsivity--fast, premature, thoughtless or disinhibited behavior--was assessed in 58 normal, healthy participants (30 men, mean age 21.9?years). Self-reported impulsivity as measured by Adaptive and Maladaptive Impulsivity Scale (AMIS) and behavioral excitatory and inhibitory processes as measured by Stop Signal Task were not directly related. Time perception, measured by the retrospective Time Estimation Task, was related to both. The length of the perceived time interval was positively correlated to AMIS Disinhibition subscale and negatively to several Stop Signal Task parameters. The longer subjects perceived the duration to last, the higher was their score on Disinhibition scale and the faster were their reactive responses in the Stop Signal Task. In summary our findings support the idea of cognitive tempo as a possible mechanism underlying impulsive behavior.

Havik M; Jakobson A; Tamm M; Paaver M; Konstabel K; Uusberg A; Allik J; Oöpik V; Kreegipuu K

2012-06-01

256

Stability of Impulsive Differential Equation with any Time Delay  

Directory of Open Access Journals (Sweden)

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

Sanjay K. Srivastava; Kanwalpreet Kaur

2013-01-01

257

Time Domain Modeling of Powerline Impulsive Noise at Its Source  

Directory of Open Access Journals (Sweden)

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

Hassina Chaouche; Frederic Gauthier; Ahmed Zeddam; Mohamed Tlich; Mohamed Machmoum

2011-01-01

258

Epoch versus impulse models in the analysis of parametric fMRI studies.  

UK PubMed Central (United Kingdom)

OBJECTIVE: In parametric fMRI studies the relationship between the amplitude of the hemodynamic response and electrophysiological or behavioral parameters is commonly analyzed using the general linear model (GLM). We examined ways of using single-trial response time (RT) in the analysis of a decision-making task to better isolate task-specific activation. METHODS: fMRI and RT data were recorded in twenty-one subjects performing a visual-oddball-task. Four explanatory variables (EVs) were generated for the GLM-analysis: A conventional (constant impulse) EV, a constant epoch EV informed using subjects' average RT, a variable impulse EV and a variable epoch EV both informed using single-trial RT. EVs were tested individually and as orthogonalized pairs. RESULTS: The individual EVs all detected similar extensive patterns of activation, while orthogonalized EVs were mainly correlated with BOLD signal variance in sensorimotor and parietal areas. Orthogonalizing the variable epoch EV to the constant epoch EV isolated cortical regions resembling the "dorsal frontoparietal attention network" from activation detected by the conventional (i.e., constant impulse) analysis. CONCLUSION: For short event durations, the activation detected by individual EVs is very similar, but orthogonalized, parametrically informed EVs can improve isolation of task-specific BOLD signal change. SIGNIFICANCE: Different approaches for integrating parametric timing measures in fMRI analyses can significantly influence outcomes, refining or confounding findings.

Richter N; Warbrick T; Mobascher A; Brinkmeyer J; Musso F; Stoecker T; Shah NJ; Fink GR; Winterer G

2013-05-01

259

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

International Nuclear Information System (INIS)

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

2007-01-01

260

Impulsivity modulates performance under response uncertainty in a reaching task.  

UK PubMed Central (United Kingdom)

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

Tzagarakis C; Pellizzer G; Rogers RD

2013-03-01

 
 
 
 
261

Alcohol increases impulsivity and abuse liability in heavy drinking women.  

Science.gov (United States)

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

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

2012-10-15

262

Impulsive Control for Synchronization of Lorenz Chaotic System  

Directory of Open Access Journals (Sweden)

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

2013-01-01

263

Impulse control in Kalman-like filtering problems  

Directory of Open Access Journals (Sweden)

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

Michael V. Basin; Mark A. Pinsky

1998-01-01

264

Correlation Between Steady State and Impulse Earth Resistance Values  

Directory of Open Access Journals (Sweden)

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

N. M. Nor; R. Rajab

2009-01-01

265

Stability of impulsive neural networks with time delays  

International Nuclear Information System (INIS)

[en] 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

2005-12-19

266

Synchronization of impulsively coupled complex systems with delay.  

UK PubMed Central (United Kingdom)

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 W; Austin F; Lü J; Chen S

2011-09-01

267

CO2 laser with long impulsions of high energy  

International Nuclear Information System (INIS)

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

1979-01-01

268

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

UK PubMed Central (United Kingdom)

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 being 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 excitastion primitives) can be used as input drive for large musculoskeletal models across different human locomotion tasks. For this purpose, we extracted, with non-negative matrix factorization, five non-negative factors from a large sample of muscle electromyograms in two healthy subjects during four motor tasks. These included 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 R (2) = 0.73 ± 0.22 across all tasks and subjects) without substantial loss of accuracy with respect to using experimental electromyograms (i.e., NRMSE = 0.16 ± 0.07, and R (2) = 0.78 ± 0.18 across all tasks and subjects). Results support the hypothesis that biomechanically 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.

Sartori M; Gizzi L; Lloyd DG; Farina D

2013-01-01

269

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

Directory of Open Access Journals (Sweden)

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

Wendol A Williams; Marc N Potenza

2008-01-01

270

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

Scientific Electronic Library Online (English)

Full Text Available 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 (more) . 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 searched to identify relevant articles that were subsequently reviewed to generate this manuscript. RESULTS: Preclinical studies suggest that differential brain monoamine neuromod (more) ulation 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.

Williams, Wendol A; Potenza, Marc N

2008-05-01

271

Playing Violent Video Games Linked to Impulsive Behavior  

Science.gov (United States)

... on this page, please enable JavaScript. Playing Violent Video Games Linked to Impulsive Behavior But these same action ... making required in so-called first-person shooter video games improves visual skills but may reduce a person's ...

272

Electrical Sterilization of Juice by Discharged HV Impulse Waveform  

Directory of Open Access Journals (Sweden)

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

Hee K. Lee

2006-01-01

273

Impulsive neutral functional differential inclusions with variable times  

Directory of Open Access Journals (Sweden)

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

Mouffak Benchohra; Abdelghani Ouahab

2003-01-01

274

On eventual stability of impulsive systems of differential equations  

Directory of Open Access Journals (Sweden)

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

A. A. Soliman

2001-01-01

275

3D model of impulse compaction of moulding sands model  

Directory of Open Access Journals (Sweden)

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

M. Ganczarek; S. Ciskowski; T. Mikulczy?ski

2008-01-01

276

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.

2004-04-14

277

Impulsive stimulated light scattering from opaque materials at high pressure  

Energy Technology Data Exchange (ETDEWEB)

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 {epsilon}-iron to 115 GPa are presented.

Crowhurst, Jonathan C; Goncharov, Alexander F; Zaug, Joseph M [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94551 (United States)

2004-04-14

278

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

279

Stability Criteria for Linear Hamiltonian Systems Under Impulsive Perturbations  

CERN Document Server

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

2011-01-01

280

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.

Mouffak Benchohra; Boualem Attou Slimani

2009-01-01

 
 
 
 
281

Lightning Impulse Waveform Parameters Abstraction Based on High Speed Filter  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A simple, shortcut and accurate algorithm is needed in lightning Impulse waveforms (include chopped wave) parameters abstraction in embedded system. Algorithm is put forward which implements mountain shape template convolution by forming rectangle template convolution two times. This method greatly ...

Xiaodong Zheng; Xinghan Huang; Min Wang

282

Multiple solutions for nonresonance impulsive functional differential equations  

Directory of Open Access Journals (Sweden)

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

Mouffak Benchohra; Abdelghani Ouahab

2003-01-01

283

Which dimensions of impulsivity are related to cigarette craving?  

Science.gov (United States)

Cigarette smoking is a very important health problem and represents the largest preventable risk factor for premature death in developed countries. A considerable body of research indicates that impulsivity is a central etiological concept in many theoretical models of tobacco addiction. The aim of this study is to analyse which dimensions of impulsivity are related to cigarette craving. To this end, 40 undergraduate psychology students were screened using the revised Questionnaire on Smoking Urges (QSU-12) and the French adaptation of the UPPS Impulsive Behavior Scale (UPPS). This scale identifies four distinct components associated with impulsive behaviour: urgency, lack of premeditation, lack of perseverance, and sensation seeking. The results showed that urgency is a significant predictor of tobacco cravings, while depression and anxiety are not. PMID:16997490

Billieux, Joël; Van der Linden, Martial; Ceschi, Grazia

2006-09-25

284

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

UK PubMed Central (United Kingdom)

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

2013-01-01

285

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

286

Jet formation from impulsive cavity collapse  

Science.gov (United States)

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

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

2006-11-01

287

Reactive high power impulse magnetron sputtering  

Science.gov (United States)

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

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

2012-10-01

288

OUTWARD BRAZILIAN FOREIGN DIRECT INVESTMENT: IMPULSES AND RESPONSES OUTWARD BRAZILIAN FOREIGN DIRECT INVESTMENT: IMPULSES AND RESPONSES  

Directory of Open Access Journals (Sweden)

Full Text Available This paper models the outward foreign direct investment from Brazil series using time a series econometrics model, namely the Vector Auto Regressive (VAR) model. We have drawn impulse response functions for the key relevant factors that may explain the outward foreign direct investment flows. We start with a review of the literature on the Dunning location approach to international business. We worked with a data set of quarterly observations from Q1-1995 to Q1-2010. We carried also out Granger causality tests as for determining whether international business travelling should be included as an explanatory variable in our model. Results stressed that although the strong exchange rate in Brazil is often blamed for forcing companies to invest abroad, the evidence found in the aggregate data suggests that there is not a significant relationship between the level of foreign exchange rate and the outward Brazilian foreign direct investment. Differently from previous studies, this paper uses impulse response functions to present dynamic results, thus avoiding the typical binary results “affect” or “don’t affect”, and in so doing we provide a more detailed insight into this important location factor.This paper models the outward foreign direct investment from Brazil series using time a series econometrics model, namely the Vector Auto Regressive (VAR) model. We have drawn impulse response functions for the key relevant factors that may explain the outward foreign direct investment flows. We start with a review of the literature on the Dunning location approach to international business. We worked with a data set of quarterly observations from Q1-1995 to Q1-2010. We carried also out Granger causality tests as for determining whether international business travelling should be included as an explanatory variable in our model. Results stressed that although the strong exchange rate in Brazil is often blamed for forcing companies to invest abroad, the evidence found in the aggregate data suggests that there is not a significant relationship between the level of foreign exchange rate and the outward Brazilian foreign direct investment. Differently from previous studies, this paper uses impulse response functions to present dynamic results, thus avoiding the typical binary results “affect” or “don’t affect”, and in so doing we provide a more detailed insight into this important location factor.

Ronald de Oliveira Concer; Frederico Araujo Turolla; Mário Antonio Margarido

2010-01-01

289

Nonexpanding impulsive gravitational waves with an arbitrary cosmological constant  

CERN Document Server

Exact solutions for nonexpanding impulsive waves in a background with nonzero cosmological constant are constructed using a `cut and paste' method. These solutions are presented using a unified approach which covers the cases of de Sitter, anti-de Sitter and Minkowski backgrounds. The metrics are presented in continuous and distributional forms, both of which are conformal to the corresponding metrics for impulsive pp-waves, and for which the limit as

Podolsky, J

1999-01-01

290

Hazard from intense low-frequency acoustic impulses. Final report  

Energy Technology Data Exchange (ETDEWEB)

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

Price, G.R.

1986-10-01

291

Attentional blink in adolescents with varying levels of impulsivity.  

Science.gov (United States)

We explore the temporal attention function in a non-clinical sample of adolescents varying in impulsivity, as assessed with the Barratt Impulsiveness Scale. In a Rapid Serial Visual Presentation task, in which two targets (T(1) and T(2)) were presented in close temporal proximity among distractors, participants tried to identify T(1) and detect T(2) in one (dual-task) experiment and only to detect T(2) in a second, control (single-task) experiment. The sensitivity of T(2) detection was analyzed using signal detection theory. The attentional blink -- the impairment in T(2) detection following the identification of T(1) -- was increased in magnitude and protracted in adolescents with high impulsivity, compared with those with low impulsivity. Moreover, a few more participants with high impulsivity appeared to have a blink temporally weighing toward a later time, an observation also made in children with attention deficit hyperactivity disorder (ADHD) in an earlier study. Taken together, these findings suggest impairment in temporal attention in adolescents with high impulsivity. As in ADHD children, a gating deficit may play a central role in this attention impairment. PMID:15589569

Ray Li, Chiang-Shan; Chen, Sue-Huei; Lin, Wei-Hao; Yang, Yong-Yi

2005-03-01

292

Attentional blink in adolescents with varying levels of impulsivity.  

UK PubMed Central (United Kingdom)

We explore the temporal attention function in a non-clinical sample of adolescents varying in impulsivity, as assessed with the Barratt Impulsiveness Scale. In a Rapid Serial Visual Presentation task, in which two targets (T(1) and T(2)) were presented in close temporal proximity among distractors, participants tried to identify T(1) and detect T(2) in one (dual-task) experiment and only to detect T(2) in a second, control (single-task) experiment. The sensitivity of T(2) detection was analyzed using signal detection theory. The attentional blink -- the impairment in T(2) detection following the identification of T(1) -- was increased in magnitude and protracted in adolescents with high impulsivity, compared with those with low impulsivity. Moreover, a few more participants with high impulsivity appeared to have a blink temporally weighing toward a later time, an observation also made in children with attention deficit hyperactivity disorder (ADHD) in an earlier study. Taken together, these findings suggest impairment in temporal attention in adolescents with high impulsivity. As in ADHD children, a gating deficit may play a central role in this attention impairment.

Ray Li CS; Chen SH; Lin WH; Yang YY

2005-03-01

293

On Impulsive Control for Synchronization and Its Application to Matsumoto-Chua-Kobayashi (MCK) Circuit  

International Nuclear Information System (INIS)

The issue of impulsive control theory for synchronization of the MCK circuit is developed. We propose an impulsive control scheme for the complete synchronization of the MCK circuit including chaotic systems. A sufficient condition for the impulsive control is derived, with an easily calculated maximum impulsive interval. The proposed impulsive control scheme is applied to the MCK circuit and the simulation result demonstrates the effectiveness of the method.

2007-08-15

294

On Impulsive Control for Synchronization and Its Application to Matsumoto-Chua-Kobayashi (MCK) Circuit  

Science.gov (United States)

The issue of impulsive control theory for synchronization of the MCK circuit is developed. We propose an impulsive control scheme for the complete synchronization of the MCK circuit including chaotic systems. A sufficient condition for the impulsive control is derived, with an easily calculated maximum impulsive interval. The proposed impulsive control scheme is applied to the MCK circuit and the simulation result demonstrates the effectiveness of the method.

Li, Yang; Liao, Xiao-Feng; Li, Chuan-Dong; Wang, Yong

2007-08-01

295

How phenotype and developmental stage affect the genes we find: GABRA2 and impulsivity.  

UK PubMed Central (United Kingdom)

CONTEXT: The detection and replication of genes involved in psychiatric outcome has been notoriously difficult. Phenotypic measurement has been offered as one explanation, although most of this discussion has focused on problems with binary diagnoses. OBJECTIVE: This article focuses on two additional components of phenotypic measurement that deserve further consideration in evaluating genetic associations: (1) the measure used to reflect the outcome of interest, and (2) the developmental stage of the study population. We focus our discussion of these issues around the construct of impulsivity and externalizing disorders, and the association of these measures with a specific gene, GABRA2. DESIGN, SETTING, AND PARTICIPANTS: Data were analyzed from the Collaborative Study on the Genetics of Alcoholism Phase IV assessment of adolescents and young adults (ages 12-26; N = 2,128). MAIN OUTCOME MEASURES: Alcohol dependence, illicit drug dependence, childhood conduct disorder, and adult antisocial personality disorder symptoms were measured by psychiatric interview; Achenbach youth/adult self-report externalizing scale; Zuckerman Sensation-Seeking scale; Barratt Impulsivity scale; NEO extraversion and consciousness. RESULTS: GABRA2 was associated with subclinical levels of externalizing behavior as measured by the Achenbach in both the adolescent and young adult samples. Contrary to previous associations in adult samples, it was not associated with clinical-level DSM symptom counts of any externalizing disorders in these younger samples. There was also association with sensation-seeking and extraversion, but only in the adolescent sample. There was no association with the Barratt impulsivity scale or conscientiousness. CONCLUSIONS: Our results suggest that the pathway by which GABRA2 initially confers risk for eventual alcohol problems begins with a predisposition to sensation-seeking early in adolescence. The findings support the heterogeneous nature of impulsivity and demonstrate that both the measure used to assess a construct of interest and the age of the participants can have profound implications for the detection of genetic associations.

Dick DM; Aliev F; Latendresse S; Porjesz B; Schuckit M; Rangaswamy M; Hesselbrock V; Edenberg H; Nurnberger J; Agrawal A; Bierut L; Wang J; Bucholz K; Kuperman S; Kramer J

2013-06-01

296

Acute alcohol effects on subtypes of impulsivity and the role of alcohol-outcome expectancies.  

UK PubMed Central (United Kingdom)

RATIONALE: It is well established that alcohol acutely impairs the ability to inhibit a pre-potent response (motor impulsivity), but its effects on cognitive impulsivity, including temporal (delayed gratification) and reflection (decision making) impulsivity, are not clear. An important factor contributing to the effects of alcohol is cognitive expectancies of alcohol-related outcomes. OBJECTIVES: The current study investigated the effect of alcohol, and alcohol outcome expectancies, on subtypes of impulsivity. METHODS: Impulsivity was tested using the Stop Signal, the Single Key Impulsivity and the Information Sampling Task for motor, temporal and reflection impulsivity, respectively. Participants (n?=?48) received placebo, a low (0.4 g/kg) or high dose (0.8 g/kg) of alcohol, before completing the impulsivity measures. RESULTS: Motor impulsivity was affected by alcohol dose; participants receiving a high dose displayed reduced inhibitory control. Reflection impulsivity was affected by cognitive alcohol expectancies, but not by alcohol condition; participants expecting greater cognitive and behavioural impairment by alcohol exhibited low impulsivity. Temporal impulsivity was not affected by either alcohol dose or outcome expectancies. CONCLUSIONS: These data suggest that the effects of alcohol on the subtypes of impulsivity are dissociable. Motor impulsivity is sensitive to the pharmacological effects of alcohol, whereas the reflection subtype is affected by cognitive alcohol expectancies. The findings have implications for the understanding of impulsive behaviour under the influence of alcohol.

Caswell AJ; Morgan MJ; Duka T

2013-09-01

297

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)

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

2012-01-01

298

Examining impulse-variability in overarm throwing.  

Science.gov (United States)

The purpose of this study was to examine variability in overarm throwing velocity and spatial output error at various percentages of maximum to test the prediction of an inverted-U function as predicted by impulse-variability theory and a speed-accuracy trade-off as predicted by Fitts' Law Thirty subjects (16 skilled, 14 unskilled) were instructed to throw a tennis ball at seven percentages of their maximum velocity (40-100%) in random order (9 trials per condition) at a target 30 feet away. Throwing velocity was measured with a radar gun and interpreted as an index of overall systemic power output. Within-subject throwing velocity variability was examined using within-subjects repeated-measures ANOVAs (7 repeated conditions) with built-in polynomial contrasts. Spatial error was analyzed using mixed model regression. Results indicated a quadratic fit with variability in throwing velocity increasing from 40% up to 60%, where it peaked, and then decreasing at each subsequent interval to maximum (p < .001, ?2 = .555). There was no linear relationship between speed and accuracy. Overall, these data support the notion of an inverted-U function in overarm throwing velocity variability as both skilled and unskilled subjects approach maximum effort. However, these data do not support the notion of a speed-accuracy trade-off. The consistent demonstration of an inverted-U function associated with systemic power output variability indicates an enhanced capability to regulate aspects of force production and relative timing between segments as individuals approach maximum effort, even in a complex ballistic skill. PMID:22402218

Urbin, M A; Stodden, David; Boros, Rhonda; Shannon, David

2012-01-01

299

Examining impulse-variability in overarm throwing.  

UK PubMed Central (United Kingdom)

The purpose of this study was to examine variability in overarm throwing velocity and spatial output error at various percentages of maximum to test the prediction of an inverted-U function as predicted by impulse-variability theory and a speed-accuracy trade-off as predicted by Fitts' Law Thirty subjects (16 skilled, 14 unskilled) were instructed to throw a tennis ball at seven percentages of their maximum velocity (40-100%) in random order (9 trials per condition) at a target 30 feet away. Throwing velocity was measured with a radar gun and interpreted as an index of overall systemic power output. Within-subject throwing velocity variability was examined using within-subjects repeated-measures ANOVAs (7 repeated conditions) with built-in polynomial contrasts. Spatial error was analyzed using mixed model regression. Results indicated a quadratic fit with variability in throwing velocity increasing from 40% up to 60%, where it peaked, and then decreasing at each subsequent interval to maximum (p < .001, ?2 = .555). There was no linear relationship between speed and accuracy. Overall, these data support the notion of an inverted-U function in overarm throwing velocity variability as both skilled and unskilled subjects approach maximum effort. However, these data do not support the notion of a speed-accuracy trade-off. The consistent demonstration of an inverted-U function associated with systemic power output variability indicates an enhanced capability to regulate aspects of force production and relative timing between segments as individuals approach maximum effort, even in a complex ballistic skill.

Urbin MA; Stodden D; Boros R; Shannon D

2012-01-01

300

Occurrence statistics of magnetic impulsive events  

Directory of Open Access Journals (Sweden)

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; D. G. Sibeck; J. F. Watermann

2004-01-01

 
 
 
 
301

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; Stefano Crosara; Riccardo De Robertis; Stefano Canestrini; Emanuele Demozzi; Anna Gallotti; Roberto Pozzi Mucelli

2013-01-01

302

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

UK PubMed Central (United Kingdom)

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

Voon V; Gao J; Brezing C; Symmonds M; Ekanayake V; Fernandez H; Dolan RJ; Hallett M

2011-05-01

303

Reachable domain of spacecraft with a single tangent impulse considering trajectory safety  

Science.gov (United States)

The reachable domain of the two-body transfer orbit with a single upper-bounded tangent impulse is studied. Three cases are analyzed for either the magnitude of the tangent impulse or the initial impulse point being free, or both being free. For a fixed impulse magnitude and a free initial impulse point, the initial orbit is proved to be one of the envelopes of the reachable domain. Moreover, the trajectory safety for the transfer orbit requires a lower bound on the perigee altitude and an upper bound on the apogee altitude. Then the ranges of the impulse magnitude and the initial true anomaly can be obtained by solving quadratic and cubic inequalities, respectively. If both constraints are required for an arbitrary impulse point, the range of the impulse magnitude is obtained with impulses at the perigee and the apogee. Several numerical examples with different eccentricities are provided to show the geometry of the reachable domain and to verify the proposed method.

Zhang, Gang; Cao, Xibin; Ma, Guangfu

2013-10-01

304

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

UK PubMed Central (United Kingdom)

Several studies have examined impulsive choice behavior in spontaneously hypertensive rats (SHRs) as a possible pre-clinical model for Attention-Deficit/Hyperactivity Disorder (ADHD). However, this strain was not specifically selected for the traits of ADHD and as a result their appropriateness as a model has been questioned. The present study investigated whether SHRs would exhibit impulsive behavior in comparison to their control strain, Wistar Kyoto (WKY) rats. In addition, we evaluated a strain that has previously shown high levels of impulsive choice, the Lewis (LEW) rats and compared them with their source strain, Wistar (WIS) rats. In the first phase, rats could choose between a smaller-sooner (SS) reward of 1 pellet after 10 s and a larger-later (LL) reward of 2 pellets after 30 s. Subsequently, the rats were exposed to increases in LL reward magnitude and SS delay. These manipulations were designed to assess sensitivity to magnitude and delay within the choice task to parse out possible differences in using the strains as models of specific deficits associated with ADHD. The SHR and WKY strains did not differ in their choice behavior under either delay or magnitude manipulations. In comparison to WIS, LEW showed deficits in choice behavior in the delay manipulation, and to a lesser extent in the magnitude manipulation. An examination of individual differences indicated that the SHR strain may not be sufficiently homogeneous in their impulsive choice behavior to be considered as a viable model for impulse control disorders such as ADHD. The LEW strain may be worthy of further consideration for their suitability as an animal model.

Garcia A; Kirkpatrick K

2013-02-01

305

High-intensity drying processes---Impulse drying: Report 3  

Energy Technology Data Exchange (ETDEWEB)

The past two years of Department of Energy supported research on impulse drying have established the process as one of the most promising alternatives to conventional cylinder drying of paper and paperboard. The early work on impulse drying, documented in the first Progress Report in this series, identified the potential of the process as part of a study of several novel drying and pressing technologies. The second year's work, which is summarized in Progress Report Two included an extensive study on the response of several commercially important grades to impulse drying. The excellent performance of the process in terms of water removal, energy use and properties development was demonstrated during these studies. The present Progress Report covers work completed between October, 1986 and September, 1987. The principal project activity during that period was the design, construction, and preliminary testing of a pilot-scale roll impulse dryer. In addition to this significant equipment development task, experiments were performed to evaluate the effects of impulse drying on very wet sheets and to further develop mechanistic understanding of the process.

Lavery, H.P.

1988-02-01

306

Single species models with logistic growth and dissymmetric impulse dispersal.  

UK PubMed Central (United Kingdom)

In this paper, two classes of single-species models with logistic growth and impulse dispersal (or migration) are studied: one model class describes dissymmetric impulsive bi-directional dispersal between two heterogeneous patches; and the other presents a new way of characterizing the aggregate migration of a natural population between two heterogeneous habitat patches, which alternates in direction periodically. In this theoretical study, some very general, weak conditions for the permanence, extinction of these systems, existence, uniqueness and global stability of positive periodic solutions are established by using analysis based on the theory of discrete dynamical systems. From this study, we observe that the dynamical behavior of populations with impulsive dispersal differs greatly from the behavior of models with continuous dispersal. Unlike models where the dispersal is continuous in time, in which the travel losses associated with dispersal make it difficult for such dispersal to evolve e.g., [25,26,28], in the present study it was relatively easy for impulsive dispersal to positively affect populations when realistic parameter values were used, and a rich variety of behaviors were possible. From our results, we found impulsive dispersal seems to more nicely model natural dispersal behavior of populations and may be more relevant to the investigation of such behavior in real ecological systems.

Zhang L; Teng Z; Deangelis DL; Ruan S

2013-02-01

307

[Mental problems and impulsivity reported by adolescents: an epidemiological study].  

UK PubMed Central (United Kingdom)

OBJECTIVE: To determine whether number of self-reported impulsivity symptoms was associated with conduct problems, substance use, academic problems, relational problems and exposure to physical violence in adolescents. METHOD: A survey was developed to be used in a nationally representative general community sample. A 2-staged, stratified and clustered sampling was used. For the first stage (school selection) an equal probability, systematic random sampling and for the second stage (class selection) a simple random selection was used. The statistical analysis included the full and usable surveys obtained from 26009 students (97.5% of the invited sample). RESULTS: After parental education, parental employment, economic status and age; presence of antisocial behaviors; substance abuse; and exposure to physical violence were controlled, presence of even one self-reported impulsivity symptom was associated with physical violence, frequent smoking, frequent alcohol use, substance use, self injurious behaviors, carrying weapons, gang membership, poor relations with others, academic failure and poor mental health. ORs increased with the number of self-reported impulsivity symptoms for several behaviors. Several other associations among conduct problems, substance use, academic failure and relational problems are also reported. CONCLUSION: Even one definite impulsivity symptom must be addressed since it is associated with serious behavioral and relational problems. There may be dose-response interaction between the number of definite impulsivity symptoms and behavioral and relational problems.

Öner Ö; Ergüder T; Çak?r B; Ergun U; Er?ahin Y; Erol N; Özcebe H

2013-01-01

308

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; S. Usa

2005-01-01

309

Acetyl-L-carnitine reduces impulsive behaviour in adolescent rats.  

Science.gov (United States)

The attention deficit/hyperactivity disorder (ADHD) can affect human infants and adolescents. One important feature of this disorder is behavioural impulsivity. This study assessed the ability of chronic acetyl-L-carnitine (ALC, saline or 100 mg/kg SC, plus 50 mg/kg orally) to reduce impulsivity in a validated animal model for ADHD. Food-restricted rats were tested during adolescence (postnatal days, pnd, 30-45) in operant chambers with two nose-poking holes, one delivering one food pellet immediately, and the other five pellets after a delay. Delay length was increased over days (from 0 to 80 s). Individual differences in the preference-delay curve emerged, with the identification of two distinct subpopulations, i.e. one with a nearly horizontal curve and another with a very steep ("impulsive") slope. The impulsivity profile was slightly but consistently reduced by chronic ALC administration. Consistent results were also obtained with methylphenidate (MPH, saline or 3 mg/kg IP twice daily). Impulsive rats exhibited a lower metabolite/serotonin (5HIAA/5HT) ratio in the medial frontal cortex (MFC) and lower noradrenaline (NA) levels in the MFC and cingulate cortex (CC) when compared with the other subgroup. The ALC treatment increased NA levels in the CC and the 5HIAA/5HT ratio in both CC and MFC. Present data suggest that ALC, a drug devoid of psychostimulant properties, may have some beneficial effects in the treatment of ADHD children. PMID:15138763

Adriani, Walter; Rea, Monica; Baviera, Marta; Invernizzi, William; Carli, Mirjana; Ghirardi, Orlando; Caprioli, Antonio; Laviola, Giovanni

2004-05-08

310

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

311

Impulsivity and Risk-taking in Bipolar Disorder and Schizophrenia.  

UK PubMed Central (United Kingdom)

Impulsive risk-taking contributes to deleterious outcomes among clinical populations. Indeed, pathological impulsivity and risk-taking are common in patients with serious mental illness, and have severe clinical repercussions including novelty seeking, response disinhibition, aggression, and substance abuse. Thus, the current study seeks to examine self-reported impulsivity (Barratt Impulsivity Scale, BIS-11) and performance-based behavioral risk-taking (Balloon Analogue Risk Task, BART) in bipolar disorder and schizophrenia. Participants included 68 individuals with bipolar disorder, 38 with schizophrenia, and 36 healthy controls. Self-reported impulsivity was elevated in the bipolar group compared with schizophrenia patients and healthy controls, who did not differ from each other. On the risk-taking task, schizophrenia patients were significantly more risk-averse than the bipolar patients and controls. Aside from the diagnostic group differences, there was a significant effect of antipsychotic (AP) medication within the bipolar group: bipolar patients taking AP medications were more risk-averse than those not taking AP medications. This difference in risk-taking due to AP medications was not explained by history of psychosis. Similarly, the differences in risk-taking between schizophrenia and bipolar disorder were not fully explained by AP effects. Implications for clinical practice and future research are discussed.Neuropsychopharmacology accepted article preview online, 21 August 2013. doi:10.1038/npp.2013.218.

Reddy LF; Lee J; Davis MC; Altshuler L; Glahn DC; Miklowitz DJ; Green MF

2013-08-01

312

Impulsivity and negative mood in adolescents with loss of control eating and ADHD symptoms: an experimental study.  

Science.gov (United States)

The aim of the study was to experimentally examine the reactivity of mood and impulsivity to negative mood induction in adolescents with loss of control (LOC) eating and adolescents with attention deficit hyperactivity disorder (ADHD) symptoms. The study included eighty-eight adolescents with LOC eating, ADHD symptoms, and control. Participants self-reported on mood and participated in a stop signal task before and after negative mood induction with Cyberball. Groups did not differ in impulsivity at baseline (p > .05). The LOC group presented with greater increase of negative mood than the ADHD group, and with greater increase of impulsivity than both other groups from pre- to post-Cyberball (p < .05). Stronger reactivity of negative mood and impulsivity in LOC eating corroborates findings in adults that the concepts' association might be specific to binge eating disorder. Additionally, findings add to previous results showing emotion regulation deficits in LOC eating. Future research should examine the concepts' impact on actual eating behavior including binge eating. PMID:23757251

Hartmann, Andrea Sabrina; Rief, Winfried; Hilbert, Anja

2013-04-03

313

Impulsivity and negative mood in adolescents with loss of control eating and ADHD symptoms: an experimental study.  

UK PubMed Central (United Kingdom)

The aim of the study was to experimentally examine the reactivity of mood and impulsivity to negative mood induction in adolescents with loss of control (LOC) eating and adolescents with attention deficit hyperactivity disorder (ADHD) symptoms. The study included eighty-eight adolescents with LOC eating, ADHD symptoms, and control. Participants self-reported on mood and participated in a stop signal task before and after negative mood induction with Cyberball. Groups did not differ in impulsivity at baseline (p > .05). The LOC group presented with greater increase of negative mood than the ADHD group, and with greater increase of impulsivity than both other groups from pre- to post-Cyberball (p < .05). Stronger reactivity of negative mood and impulsivity in LOC eating corroborates findings in adults that the concepts' association might be specific to binge eating disorder. Additionally, findings add to previous results showing emotion regulation deficits in LOC eating. Future research should examine the concepts' impact on actual eating behavior including binge eating.

Hartmann AS; Rief W; Hilbert A

2013-03-01

314

Cocaine Modulation of Frontostriatal Expression of Zif268, D2, and 5-HT2c Receptors in High and Low Impulsive Rats.  

UK PubMed Central (United Kingdom)

Impulsivity shares high comorbidity with substance abuse in humans, and high impulsivity (HI) in rats has been identified as a predictive factor for cocaine addiction-like behavior. Despite the evidence that high impulsivity is associated with altered function of corticostriatal networks, the specific neural substrates underlying the increased vulnerability of impulsive individuals to develop cocaine addiction remain unknown. We therefore investigated specific neural correlates of HI within the corticostriatal circuitry and determined how they interact with a protracted history of cocaine self-administration. We used in situ hybridization to map brain expression of two major genes implicated in impulsivity, encoding the dopamine D2 receptor (DA D2R) and the 5-HT2c receptor (5-HT2cR), and an immediate early gene associated with neuronal plasticity, zif268, in groups of rats selected for HI and low impulsivity (LI) on a 5-choice serial reaction time task (5-CSRTT) immediately after 5-CSRTT training, and following 10 or 50 days of cocaine self-administration. HI rats exhibited decreased DA D2R mRNA in the mesolimbic pathway, and increased 5-HT2cR mRNA in the orbitofrontal cortex compared with LI rats. HI rats also showed decreased zif268 mRNA in the ventral and dorsomedial striatum. Cocaine exposure decreased striatal D2R mRNA in both HI and LI rats, decreased 5-HT2cR mRNA differentially in striatal and prefrontal areas between HI and LI rats, and selectively decreased zif268 mRNA in the orbitofrontal and infralimbic cortices of HI animals. These findings implicate novel markers underlying the vulnerability of impulsive rats to cocaine addiction that localize to the OFC, infralimbic cortex, and striatum.

Besson M; Pelloux Y; Dilleen R; Theobald DE; Lyon A; Belin-Rauscent A; Robbins TW; Dalley JW; Everitt BJ; Belin D

2013-09-01

315

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; Mowafak Fathi

2005-01-01

316

Classification of Buried Objects Using Impulse Radar Measurements  

UK PubMed Central (United Kingdom)

The present report deals with the problem of classifying buriedobjects based on impulse radar measurements. The motivation fordealing with this problem is mainly to clear minefields in post-warzones. Another application is to detect and clear unexploded ordnance(UXO) in military proving grounds. This has traditionally been donewith magnetometers and metal detectors. Problems with these sensorsare that some modern mines are non-metallic and that the groundcontains a lot of metal fragments from exploded bomb shells, givingrise to a lot of false alarms. The impulse radar has shown promisingresults for detecting non-metallic objects and also for extracting informationthat can be used for classification purposes. The report isfocused on classification methods and on how to extract discriminantfeatures from the impulse radar measurements. The report has theform of an evaluation of possible classification and feature extractionmethods. The results indicate that under the experim...

H. Brunzell

317

Four factors of impulsivity differentiate antisocial and borderline personality disorders.  

UK PubMed Central (United Kingdom)

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.

DeShong HL; Kurtz JE

2013-04-01

318

The relation between acting out and disorders of impulse control.  

UK PubMed Central (United Kingdom)

THE TERM acting out has been used in many different ways and has often been misused. It is frequently applied indiscriminately to behavior, especially antisocial behavior, which is viewed by the observer as difficult to understand or unacceptable. In this misuse, the term sometimes encompasses behaviors which reflect disorders of impulse control. However, acting out and disorders of impulse control differ in many ways and should be distinguished from each other. A previous communication (Frosch and Wortis, 1954) reported on the nosology of the impulse disorders without attempting to differentiate these from acting out in any extensive manner. In the present communication, it is my intention to pursue this differentiation phenomenologically, dynamically, genetically, and therapeutically.

Frosch J

1977-11-01

319

Neural mechanisms of impulse control in sexually risky adolescents.  

UK PubMed Central (United Kingdom)

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

Goldenberg D; Telzer EH; Lieberman MD; Fuligni A; Galván A

2013-06-01

320

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; Sam Olatunji Ale

2013-01-01

 
 
 
 
321

Impulse-excited pulsations during the July 29, 1977 event  

Energy Technology Data Exchange (ETDEWEB)

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

Nopper, R.W. Jr.; Hughes, W.J.; Maclennan, C.G.; McPherron, R.L.

1982-08-01

322

A New Approach to Calculating Spatial Impulse Responses  

UK PubMed Central (United Kingdom)

Using linear acoustics the emitted and scattered ultrasoundfield can be found by using spatial impulse responses as developedby Tupholme and Stepanishen. The impulse responseis calculated by the Rayleigh integral by summing the sphericalwaves emitted from all of the aperture surface. The evaluationof the integral is cumbersome and quite involved fordifferent aperture geometries. This paper re-investigates theproblem and shows that the field can be found from the crossingsbetween the boundary of the aperture and a sphericalwave emitted from the field point onto the plane of the emittingaperture. Summing the angles of the arcs within the aperturereadily yields the spatial impulse response for a point inspace. The approach makes is possible to make very generalcalculation routines for arbitrary, flat apertures in which theoutline of the aperture is either analytically or numericallydefined. The exact field can then be found without evaluatingany integrals by merely finding...

Jrgen Arendt Jensen

323

Measuring long impulse responses with pseudorandom sequences and sweep signals  

DEFF Research Database (Denmark)

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

Torras Rosell, Antoni Technical University of Denmark,

2010-01-01

324

Environmental rearing effects on impulsivity and reward sensitivity.  

UK PubMed Central (United Kingdom)

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. (PsycINFO Database Record (c) 2013 APA, all rights reserved).

Kirkpatrick K; Marshall AT; Clarke J; Cain ME

2013-10-01

325

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. (PsycINFO Database Record (c) 2013 APA, all rights reserved). PMID:24128360

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

2013-10-01

326

Criminal conviction, impulsivity, and course of illness in bipolar disorder.  

UK PubMed Central (United Kingdom)

OBJECTIVE: Criminal behavior in bipolar disorder may be related to substance use disorders, personality disorders, or other comorbidities potentially related to impulsivity. We investigated relationships among impulsivity, antisocial personality disorder (ASPD) or borderline personality disorder symptoms, substance use disorder, course of illness, and history of criminal behavior in bipolar disorder. METHODS: A total of 112 subjects with bipolar disorder were recruited from the community. Diagnosis was by Structured Clinical Interview for DSM-IV (SCID-I and SCID-II); psychiatric symptom assessment by the Change version of the Schedule for Affective Disorders and Schizophrenia (SADS-C); severity of Axis II symptoms by ASPD and borderline personality disorder SCID-II symptoms; and impulsivity by questionnaire and response inhibition measures. RESULTS: A total of 29 subjects self-reported histories of criminal conviction. Compared to other subjects, those with convictions had more ASPD symptoms, less education, more substance use disorder, more suicide attempt history, and a more recurrent course with propensity toward mania. They had increased impulsivity as reflected by impaired response inhibition, but did not differ in questionnaire-measured impulsivity. On logit analysis, impaired response inhibition and ASPD symptoms, but not substance use disorder, were significantly associated with criminal history. Subjects convicted for violent crimes were not more impulsive than those convicted for nonviolent crimes. CONCLUSIONS: In this community sample, a self-reported history of criminal behavior is related to ASPD symptoms, a recurrent and predominately manic course of illness, and impaired response inhibition in bipolar disorder, independent of current clinical state.

Swann AC; Lijffijt M; Lane SD; Kjome KL; Steinberg JL; Moeller FG

2011-03-01

327

The role of impulse control disorders in Tourette syndrome: an exploratory study.  

UK PubMed Central (United Kingdom)

INTRODUCTION: Tourette syndrome (TS) is a neurodevelopmental condition characterised by the presence of multiple motor tics and one or more phonic tics, often associated with co-morbid behavioural problems. Impulse control disorders (ICDs) are a set of disorders where patients have significant difficulties in controlling their urges to perform rewarding behaviours. ICDs are expected to be common in patients with TS, as many problems reported in TS are related to difficulties in controlling impulsivity. AIMS: This exploratory study aimed to determine the clinical characteristics of ICDs in adult patients with TS, and to investigate the relationship between the presence of ICDs and health-related quality of life (HR-QOL). METHODS: Thirty-one patients with a diagnosis of TS were screened for ICDs using the Minnesota Impulsive Disorders Interview (MIDI). HR-QOL was assessed using a generic instrument, the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) and a disease-specific scale, the Gilles de la Tourette Syndrome-Quality of Life Scale (GTS-QOL). RESULTS: Twenty-three out of 31 participants (74.2%) had at least one ICD. The most common ICDs were intermittent explosive disorder (51.6%) and compulsive buying disorder (41.9%). The number of ICDs significantly correlated with reduced HR-QOL (p=0.011) as measured by the GTS-QOL, but not by the SF-36. CONCLUSIONS: ICDs are common in patients with TS. HR-QOL measures specific to this patient population show that the presence of co-morbid ICDs results in poorer HR-QOL.

Frank MC; Piedad J; Rickards H; Cavanna AE

2011-11-01

328

Single-impulse magnetic focusing of launched cold atoms  

CERN Multimedia

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

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

2004-01-01

329

Single-impulse magnetic focusing of launched cold atoms  

Energy Technology Data Exchange (ETDEWEB)

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

Pritchard, Matthew J [Department of Physics, Rochester Building, University of Durham, South Road, Durham, DH1 3LE (United Kingdom); Arnold, Aidan S [Department of Physics, University of Strathclyde, Glasgow, G4 0NG (United Kingdom); Smith, David A [Department of Physics, Rochester Building, University of Durham, South Road, Durham, DH1 3LE (United Kingdom); Hughes, Ifan G [Department of Physics, Rochester Building, University of Durham, South Road, Durham, DH1 3LE (United Kingdom)

2004-11-28

330

Impulsive differential equations asymptotic properties of the solutions  

CERN Multimedia

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

331

Diet-induced obesity: dopamine transporter function, impulsivity and motivation.  

UK PubMed Central (United Kingdom)

Objective:A rat model of diet-induced obesity (DIO) was used to determine dopamine transporter (DAT) function, impulsivity and motivation as neurobehavioral outcomes and predictors of obesity.Design:To evaluate neurobehavioral alterations following the development of DIO induced by an 8-week high-fat diet (HF) exposure, striatal D2-receptor density, DAT function and expression, extracellular dopamine concentrations, impulsivity, and motivation for high- and low-fat reinforcers were determined. To determine predictors of DIO, neurobehavioral antecedents including impulsivity, motivation for high-fat reinforcers, DAT function and extracellular dopamine were evaluated before the 8-week HF exposure.Methods:Striatal D2-receptor density was determined by in vitro kinetic analysis of [(3)H]raclopride binding. DAT function was determined using in vitro kinetic analysis of [(3)H]dopamine uptake, methamphetamine-evoked [(3)H]dopamine overflow and no-net flux in vivo microdialysis. DAT cell-surface expression was determined using biotinylation and western blotting. Impulsivity and food-motivated behavior were determined using a delay discounting task and progressive ratio schedule, respectively.Results:Relative to obesity-resistant (OR) rats, obesity-prone (OP) rats exhibited 18% greater body weight following an 8-week HF-diet exposure, 42% lower striatal D2-receptor density, 30% lower total DAT expression, 40% lower in vitro and in vivo DAT function, 45% greater extracellular dopamine and twofold greater methamphetamine-evoked [(3)H]dopamine overflow. OP rats exhibited higher motivation for food, and surprisingly, were less impulsive relative to OR rats. Impulsivity, in vivo DAT function and extracellular dopamine concentration did not predict DIO. Importantly, motivation for high-fat reinforcers predicted the development of DIO.Conclusion:Human studies are limited by their ability to determine if impulsivity, motivation and DAT function are causes or consequences of DIO. The current animal model shows that motivation for high-fat food, but not impulsive behavior, predicts the development of obesity, whereas decreases in striatal DAT function are exhibited only after the development of obesity.

Narayanaswami V; Thompson AC; Cassis LA; Bardo MT; Dwoskin LP

2013-08-01

332

Lightning Impulse Waveform Parameters Abstraction Based on High Speed Filter  

Directory of Open Access Journals (Sweden)

Full Text Available A simple, shortcut and accurate algorithm is needed in lightning Impulse waveforms (include chopped wave) parameters abstraction in embedded system. Algorithm is put forward which implements mountain shape template convolution by forming rectangle template convolution two times. This method greatly lower down the computational complexity and obtain the time and frequency localization at same time. The results of waveform parameters obtained by this method accord with the requirements of standard IEC1083-2 completely. And it was highly consistent with standard impulse calibration instrument. The computational complexity and the ability of frequency restraining of this algorithm was analyzed.

Xiaodong Zheng; Xinghan Huang; Min Wang

2005-01-01

333

PLC Impulsive Noise in Industrial Zone: Measurement and Characterization  

Directory of Open Access Journals (Sweden)

Full Text Available Noise in PLC is of relatively complex structure ofwhich the most important component is the asynchronousimpulsive noise. Based on measurements realized in anindustrial zone, this paper shows the heavy tail phenomenonobserved in experimental measures. Consequently, the alphastable model is the most natural to be used in describing thestatistics of PLC impulsive noise in industrial zones.Furthermore, the inter-arrival time is of Pareto distributionwhile the duration of impulses follows a mixed exponentialdistribution. All parameters of the alpha stable model as well asthe Pareto parameters and the mixed exponents are statisticallyestimated. The variation of these parameters with time is alsodiscussed.

Trung H. Tran; Dung D. Do; Tue H. Huynh

2013-01-01

334

Diet-induced obesity: dopamine transporter function, impulsivity and motivation.  

Science.gov (United States)

Objective:A rat model of diet-induced obesity (DIO) was used to determine dopamine transporter (DAT) function, impulsivity and motivation as neurobehavioral outcomes and predictors of obesity.Design:To evaluate neurobehavioral alterations following the development of DIO induced by an 8-week high-fat diet (HF) exposure, striatal D2-receptor density, DAT function and expression, extracellular dopamine concentrations, impulsivity, and motivation for high- and low-fat reinforcers were determined. To determine predictors of DIO, neurobehavioral antecedents including impulsivity, motivation for high-fat reinforcers, DAT function and extracellular dopamine were evaluated before the 8-week HF exposure.Methods:Striatal D2-receptor density was determined by in vitro kinetic analysis of [(3)H]raclopride binding. DAT function was determined using in vitro kinetic analysis of [(3)H]dopamine uptake, methamphetamine-evoked [(3)H]dopamine overflow and no-net flux in vivo microdialysis. DAT cell-surface expression was determined using biotinylation and western blotting. Impulsivity and food-motivated behavior were determined using a delay discounting task and progressive ratio schedule, respectively.Results:Relative to obesity-resistant (OR) rats, obesity-prone (OP) rats exhibited 18% greater body weight following an 8-week HF-diet exposure, 42% lower striatal D2-receptor density, 30% lower total DAT expression, 40% lower in vitro and in vivo DAT function, 45% greater extracellular dopamine and twofold greater methamphetamine-evoked [(3)H]dopamine overflow. OP rats exhibited higher motivation for food, and surprisingly, were less impulsive relative to OR rats. Impulsivity, in vivo DAT function and extracellular dopamine concentration did not predict DIO. Importantly, motivation for high-fat reinforcers predicted the development of DIO.Conclusion:Human studies are limited by their ability to determine if impulsivity, motivation and DAT function are causes or consequences of DIO. The current animal model shows that motivation for high-fat food, but not impulsive behavior, predicts the development of obesity, whereas decreases in striatal DAT function are exhibited only after the development of obesity. PMID:23164701

Narayanaswami, V; Thompson, A C; Cassis, L A; Bardo, M T; Dwoskin, L P

2012-11-20

335

Exponential dichotomies for linear systems with impulsive effects  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper we give conditions for the existence of a dichotomy for the impulsive equation $$displaylines{ mu(t,varepsilon) x'= A(t)x, ; t eq t_k,cr x(t_k^+ )= C_k x(t_k^-),, }$$ where $mu(t,varepsilon)$ is a positive function such that $limmu(t,varepsilon)=0$ in some sense. The results are expressed in terms of the properties of the eigenvalues of matrices $A(t)$, the properties of the eigenvalues of matrices ${C_k}$ and the location of the impulsive times ${t_k}$ in $[0, infty)$.

Raul Naulin

2001-01-01

336

Exponential stability in Hopfield-type neural networks with impulses  

International Nuclear Information System (INIS)

[en] 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 p where p ? 1, include those governing the network parameters and the impulse magnitude and frequency

2007-01-01

337

Efficient Techniques for Denoising of Highly Corrupted Impulse Noise Images  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, different types of impulse noiseremoval techniques are presented. Because of adaptive nature ofmask size depending on the noise quantity in the image, adaptivemedian filter works better in removing the salt and pepper noise.To show the performance of Adaptive Median filter, median filter,Lee filter, Frost and Kuan filters and DWT and Duqal treeComplex Wavelet Transform are considered. Adaptive medianfilter is compared with other filters and also the transformations.The superiority of Adaptive Median filter in removing the HighlyCorrupted with impulse noise in images are presented. Graphs aredrawn between the input PSNR and output PSNR for impulsenoise removal techniques.

Suresh Velaga; Sridhar Kovvada

2012-01-01

338

Are old people so gentle? Functional and dysfunctional impulsivity in the elderly.  

UK PubMed Central (United Kingdom)

BACKGROUND: Although old people may seem less impulsive than adults, numerous experimental studies report that they have inhibitory deficits. Bearing in mind that there is a relationship between inhibition processes and impulsivity, age-related inhibition deficits suggest that older people could be more impulsive than adults. METHODS: The aim of the current study was to compare the functional and dysfunctional impulsivity scores obtained in a sample of elderly people (65 years old and above) with those obtained in previous studies on samples of adolescents and adults. Dickman's Impulsivity Inventory was administered to 190 individuals aged between 65 and 94 years without dementia or cognitive impairment. RESULTS: Results indicated that the elderly sample showed higher dysfunctional impulsivity levels than the adult samples, which is consistent with the inhibition deficits mentioned above. There were no significant differences in functional impulsivity. Furthermore, old women had higher scores than old men on dysfunctional impulsivity. CONCLUSIONS: This study provides evidence of age-related changes in dysfunctional impulsivity. Functional impulsivity did not show the same pattern as dysfunctional impulsivity, being quite stable across the age span. it seems, then, that impulsivity cannot be considered to decrease with age and dysfunctional impulsivity may even increase.

Morales-Vives F; Vigil-Colet A

2012-03-01

339

Are adolescents gambling with cannabis use? A longitudinal study of impulsivity measures and adolescent substance use: the TRAILS study.  

UK PubMed Central (United Kingdom)

OBJECTIVE: This study examined (a) the predictive value of observed versus reported measures of impulsivity on the onset of cannabis use and determined if lifetime tobacco and cannabis users can be differentiated by their level of impulsivity and (b) the predictive value of observed versus reported measures of impulsivity on repeated cannabis use and determined if repeated tobacco and cannabis users can be differentiated by their level of impulsivity. METHOD: The present study involves 667 (50.5% female) adolescents assessed at two time points of the TRacking Adolescents' Individual Lives Survey (TRAILS). Adolescents in our study participated in the Bangor Gambling Task (BGT), as well as completed self-report questionnaires assessing cannabis use behavior (Mage = 16.11 years) and the Behavioral Inhibition System (BIS)/Behavioral Activation System (BAS) questionnaire (Mage = 13.56 years). RESULTS: Higher levels of BAS functioning increased the likelihood that adolescents would ever use substances such as tobacco or cannabis during their lifetime. In contrast, low BIS functioning increased the likelihood of repeated cannabis use. Repeated tobacco users did not significantly differ from lifetime users by their BIS functioning. The BGT measures were not significant in relation to lifetime or repeated use of cannabis or tobacco. CONCLUSIONS: High BAS seems to be more important for experimental substance use, whereas low BIS seems to be more important for progression into regular cannabis use specifically. In contrast to the BIS/BAS, our laboratory test of impulsivity, the BGT, is not correlated with early-onset tobacco/cannabis use. Furthermore, the BGT is not correlated with the BIS/BAS measures.

Prince van Leeuwen A; Creemers HE; Verhulst FC; Ormel J; Huizink AC

2011-01-01

340

The Separation of ADHD Inattention and Hyperactivity-Impulsivity Symptoms: Pathways from Genetic Effects to Cognitive Impairments and Symptoms.  

UK PubMed Central (United Kingdom)

Both shared and unique genetic risk factors underlie the two symptom domains of attention deficit hyperactivity disorder (ADHD): inattention and hyperactivity-impulsivity. The developmental course and relationship to co-occurring disorders differs across the two symptom domains, highlighting the importance of their partially distinct etiologies. Familial cognitive impairment factors have been identified in ADHD, but whether they show specificity in relation to the two ADHD symptom domains remains poorly understood. We aimed to investigate whether different cognitive impairments are genetically linked to the ADHD symptom domains of inattention versus hyperactivity-impulsivity. We conducted multivariate genetic model fitting analyses on ADHD symptom scores and cognitive data, from go/no-go and fast tasks, collected on a population twin sample of 1,312 children aged 7-10. Reaction time variability (RTV) showed substantial genetic overlap with inattention, as observed in an additive genetic correlation of 0.64, compared to an additive genetic correlation of 0.31 with hyperactivity-impulsivity. Commission errors (CE) showed low additive genetic correlations with both hyperactivity-impulsivity and inattention (genetic correlations of 0.17 and 0.11, respectively). The additive genetic correlation between RTV and CE was also low and non-significant at -0.10, consistent with the etiological separation between the two indices of cognitive impairments. Overall, two key cognitive impairments phenotypically associated with ADHD symptoms, captured by RTV and CE, showed different genetic relationships to the two ADHD symptom domains. The findings extend a previous model of two familial cognitive impairment factors in combined subtype ADHD by separating pathways underlying inattention and hyperactivity-impulsivity symptoms.

Kuntsi J; Pinto R; Price TS; van der Meere JJ; Frazier-Wood AC; Asherson P

2013-07-01

 
 
 
 
341

Studies of the blow off impulses in the aluminum alloy targets irradiated by intense pulsed X-ray  

International Nuclear Information System (INIS)

The studies of the blow off impulses produced in the aluminum alloy targets irradiated by intense pulsed X-ray are discussed. In experiments, the probe principle of directly measuring the specific series of time intervals and variable reluctance transduction technique was used. In computation, an analytic computing method was used. The results show that the computed values are in basically agreements with that of the measured

1998-01-01

342

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

Directory of Open Access Journals (Sweden)

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

Qiaoluan Li; Wing-Sum Cheung

2013-01-01

343

A Study on the Development of Standard Measuring System for Switching Impulse Voltage (III)  

Energy Technology Data Exchange (ETDEWEB)

This study aims to develop reference switching impulse voltage measuring system and to accumulate the basic data that is essential to evaluate characteristics of industrial switching impulse voltage test. Also this study aims to show the basic data for establishment in the calibration system of switching impulse voltage test in the our country. In this study, the reference measuring system were developed to satisfy the IEC standard for switching impulse voltage. The main results obtained from the study are summarized as follows : (a) Investigation on the characteristic parameters of reference switching impulse measuring system that is resistive type (b) Design and construction of reference switching impulse divider (c) Evaluation of reference switching impulse divider (d) Investigation of the institutional systematization of calibration system for switching impulse voltage. (author) refs., figs., tabs.

Kim, I. S.; Choi, B. J.; Lee, H. H.; Kim, Y. B.; Kim, M. K.; Seo, K. S.; Kim, J. G.; Moon, I. W. [Korea Electrotechnology Research Institute, Changwon (Korea, Republic of); Han, J. H.; Kim, C. K.; Oh, C. G.; Kim, J. H. [Shin-A Electric Ind. Co., Ltd, Ansan (Korea, Republic of)

1996-12-01

344

Impulse propagation from the SA-node to the ventricles.  

UK PubMed Central (United Kingdom)

Normally the pacemaker of the mammalian heart is located in the sinus node. In the rabbit the sinus node can be subdivided into two regions, the center of the node where the impulse originates and the border zone through which the impulse is conducted towards the atrium. Conduction properties of both regions were investigated. It appeared that conduction velocity increases and refractoriness decreases when one goes from the nodal center towards the atrium. The tissue mass of the atrium is large in comparison to the sinus node and normally the resting membrane potential of atrial fibers is more negative than that of nodal fibers; consequently, a potential difference exists causing a current flow between both areas. Evidently this hyperpolarizing current flow depresses impulse formation in the border zone fibers which have better intrinsic pacemaker properties than fibers in the nodal center. If the impulse has reached the atrium it is conducted with a relatively high safety factor and will reach the AV node in principle without difficulty. The AV node, if deprived of sinus nodal dominance, develops spontaneous activity originating from the lower nodal fibers. Also in this structure, electrotonic depression by surrounding tissue causes deceleration of the pacemaker.

Bonke FI; Kirchhof CJ; Allessie MA; Wit AL

1987-10-01

345

Impulse propagation from the SA-node to the ventricles.  

Science.gov (United States)

Normally the pacemaker of the mammalian heart is located in the sinus node. In the rabbit the sinus node can be subdivided into two regions, the center of the node where the impulse originates and the border zone through which the impulse is conducted towards the atrium. Conduction properties of both regions were investigated. It appeared that conduction velocity increases and refractoriness decreases when one goes from the nodal center towards the atrium. The tissue mass of the atrium is large in comparison to the sinus node and normally the resting membrane potential of atrial fibers is more negative than that of nodal fibers; consequently, a potential difference exists causing a current flow between both areas. Evidently this hyperpolarizing current flow depresses impulse formation in the border zone fibers which have better intrinsic pacemaker properties than fibers in the nodal center. If the impulse has reached the atrium it is conducted with a relatively high safety factor and will reach the AV node in principle without difficulty. The AV node, if deprived of sinus nodal dominance, develops spontaneous activity originating from the lower nodal fibers. Also in this structure, electrotonic depression by surrounding tissue causes deceleration of the pacemaker. PMID:3311792

Bonke, F I; Kirchhof, C J; Allessie, M A; Wit, A L

1987-10-15

346

Laboratory Measured Behavioral Impulsivity Relates to Suicide Attempt History  

Science.gov (United States)

|The purpose of this study was to examine the relationship between laboratory behavioral measured impulsivity (using the Immediate and Delayed Memory Tasks) and suicidal attempt histories. Three groups of adults were recruited, those with either: no previous suicide attempts (Control, n = 20), only a single suicide attempt (Single, n = 20), or…

Dougherty, Donald M.; Mathias, Charles W.; Marsh, Dawn M.; Papageorgiou, T. Dorina; Swann, Alan C.; Moeller, F. Gerard

2004-01-01

347

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

348

Global asymptotic stability of delay BAM neural networks with impulses  

International Nuclear Information System (INIS)

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

2006-01-01

349

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Impulsive-compulsive behaviours (ICBs) are an increasingly well-recognised adverse-effect of dopaminergic medications used to treat Parkinson's disease. ICBs include pathological gambling, compulsive sexual behaviour, compulsive buying, and binge eating, together with punding and the addiction-like ...

Djamshidian, A; Averbeck, BB; Lees, AJ; O'Sullivan, SS

350

Space-time diagnostics of reactive impulse plasma  

Energy Technology Data Exchange (ETDEWEB)

Spectral investigations of the space-time distribution of reactive impulse plasma ejected from a coaxial accelerator were carried out. A two-zone structure of the plasmoid, related to interactions between the gas plasma and the accelerator electrode, was found. The isotropization kinetics of the chemical composition of the plasmoid was determined.

Walkowicz, J.; Sekula, J.

1987-10-01

351

Second-order adaptive infinite impulse response filter  

Energy Technology Data Exchange (ETDEWEB)

A simple second-order infinite impulse response (IIR) filter is introduced. An efficient algorithm to use it as a line enhancer and tracker is presented. The related experimental results demonstrate that it can be used very effectively to enhance and track a single or dominant sinusoid in broadband noise.

Ahmed, N.; Hush, D.; Elliott, G.R.; Fogler, R.J.

1983-01-01

352

Inhibition and impulsivity: Behavioral and neural basis of response control.  

Science.gov (United States)

In many circumstances alternative courses of action and thoughts have to be inhibited to allow the emergence of goal-directed behavior. However, this has not been the accepted view in the past and only recently has inhibition earned its own place in the neurosciences as a fundamental cognitive function. In this review we first introduce the concept of inhibition from early psychological speculations based on philosophical theories of the human mind. The broad construct of inhibition is then reduced to its most readily observable component which necessarily is its behavioral manifestation. The study of 'response inhibition' has the advantage of dealing with a relatively simple and straightforward process, the overriding of a planned or already initiated action. Deficient inhibitory processes profoundly affect everyday life, causing impulsive conduct which is generally detrimental for the individual. Impulsivity has been consistently linked to several types of addiction, attention deficit/hyperactivity disorder, mania and other psychiatric conditions. Our discussion of the behavioral assessment of impulsivity will focus on objective laboratory tasks of response inhibition that have been implemented in parallel for humans and other species with relatively few qualitative differences. The translational potential of these measures has greatly improved our knowledge of the neurobiological basis of behavioral inhibition and impulsivity. We will then review the current models of behavioral inhibition along with their expression via underlying brain regions, including those involved in the activation of the brain's emergency 'brake' operation, those engaged in more controlled and sustained inhibitory processes and other ancillary executive functions. PMID:23856628

Bari, Andrea; Robbins, Trevor W

2013-07-13

353

A recursive adaptive lattice filters for impulsive signals  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The existence of impulsive noise with alpha-stable distributions has been addressed in many applications. Some adaptive lattice algorithms that factional lower order moments of residual errors are used to updated the filter coefficients are presented. In this paper, a new recursive adaptive lattice ...

Li, S; Qiu, T-S; Lin, B; Yu, D-W

354

Statistically-Efficient Filtering in Impulsive Environments: Weighted Myriad Filters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Linear filtering theory has been largely motivated by the characteristics of Gaussian signals. In the same manner, the proposed Myriad Filtering methods are motivated by the need for a flexible filter class with high statistical efficiency in non-Gaussian impulsive environments that can appear in pr...

Gonzalo R. Arce; Juan G. Gonzalez

355

Periodic components of hand acceleration/deceleration impulses during telemanipulation  

Energy Technology Data Exchange (ETDEWEB)

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.

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

1994-01-01

356

Time Domain Modeling of Powerline Impulsive Noise at Its Source  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Noise characteristics of an indoor power line network strongly influence the link capability to achieve high data rates. The appliances shared with PLC modems in the same powerline network generate different types of noises, among them the impulsive noises are the main source of interference resulti...

Hassina Chaouche; Frederic Gauthier; Ahmed Zeddam; Mohamed Tlich; Mohamed Machmoum

357

Internal current measurements in high power impulse magnetron sputtering  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The transport of charged particles in a high power impulse magnetron sputtering (HiPIMS) discharge is of great interest when optimizing this promising deposition technique with respect to deposition rate and control of the ion acceleration. In this study the internal current densities J? (azimuthal ...

Lundin, Daniel; Al Sahab, Seham; Brenning, Nils; Huo, Chunqing; Helmersson, Ulf

358

The regularity of geodesics in impulsive pp-waves  

CERN Document Server

We consider the geodesic equation in impulsive pp-wave space-times in Rosen form, where the metric is of Lipschitz regularity. We prove that the geodesics (in the sense of Caratheodory) are actually continuously differentiable, thereby rigorously justifying the $C^1$-matching procedure which has been used in the literature to explicitly derive the geodesics in space-times of this form.

Lecke, Alexander; Svarc, Robert

2013-01-01

359

Existence of solutions to singular fractional differential systems with impulses  

Directory of Open Access Journals (Sweden)

Full Text Available By constructing a weighted Banach space and a completely continuous operator, we establish the existence of solutions for singular fractional differential systems with impulses. Our results are proved using the Leray-Schauder nonlinear alternative, and are illustrated with examples.

Xingyuan Liu; Yuji Liu

2012-01-01

360

The Impulse toward Comedy in Margaret Atwood's Poetry.  

Science.gov (United States)

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

Benton, Carol L.

 
 
 
 
361

Radiative muon capture: impulse approximation and the continuity equation  

International Nuclear Information System (INIS)

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

1983-01-01

362

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 gav...

Judaev I.V.

363

Correlation Between Steady State and Impulse Earth Resistance Values  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study presented experimental results of earthing systems under low-magnitude currents and under high impulse currents. The details of the measuring circuit involved for both types of testing were described. Three field sites were selected. At each site, three earth electrodes configurations wer...

N. M. Nor; R. Rajab

364

Clinical features associated with impulse control disorders in Parkinson disease.  

UK PubMed Central (United Kingdom)

In patients with Parkinson disease (PD), impulse control disorders (ICDs) such as hypersexuality and pathologic gambling and shopping can be devastating complications of antiparkinsonian treatment. To improve their detection, we investigated clinical features associated with ICDs. Subjects were participants in a longitudinal study of PD. ICDs were associated with use of dopamine agonists and depressed mood, disinhibition, irritability, and appetite disturbance.

Pontone G; Williams JR; Bassett SS; Marsh L

2006-10-01

365

Inhibition and impulsivity: Behavioral and neural basis of response control.  

UK PubMed Central (United Kingdom)

In many circumstances alternative courses of action and thoughts have to be inhibited to allow the emergence of goal-directed behavior. However, this has not been the accepted view in the past and only recently has inhibition earned its own place in the neurosciences as a fundamental cognitive function. In this review we first introduce the concept of inhibition from early psychological speculations based on philosophical theories of the human mind. The broad construct of inhibition is then reduced to its most readily observable component which necessarily is its behavioral manifestation. The study of 'response inhibition' has the advantage of dealing with a relatively simple and straightforward process, the overriding of a planned or already initiated action. Deficient inhibitory processes profoundly affect everyday life, causing impulsive conduct which is generally detrimental for the individual. Impulsivity has been consistently linked to several types of addiction, attention deficit/hyperactivity disorder, mania and other psychiatric conditions. Our discussion of the behavioral assessment of impulsivity will focus on objective laboratory tasks of response inhibition that have been implemented in parallel for humans and other species with relatively few qualitative differences. The translational potential of these measures has greatly improved our knowledge of the neurobiological basis of behavioral inhibition and impulsivity. We will then review the current models of behavioral inhibition along with their expression via underlying brain regions, including those involved in the activation of the brain's emergency 'brake' operation, those engaged in more controlled and sustained inhibitory processes and other ancillary executive functions.

Bari A; Robbins TW

2013-09-01

366

Solar Flare Impulsive Phase Emission Observed with SDO/EVE  

CERN Multimedia

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

367

Periodic components of hand acceleration/deceleration impulses during telemanipulation  

International Nuclear Information System (INIS)

[en] 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

1994-01-15

368

High energy nucleon incident optical potential by relativistic impulse approximation  

International Nuclear Information System (INIS)

[en] The optical potentials by relativistic impulse approximation (RIA) are utilized for the high energy nucleon incidence. The nucleon-nucleon scattering amplitudes are derived from the phase shift and parametrized as a function of the incident nucleon energy. The optical potential by RIA reproduces the experimental data. (author)

2000-01-01

369

Vestibulo-ocular reflex and the head impulse test.  

UK PubMed Central (United Kingdom)

The authors highlights the importance of the vestibulo-ocular reflex examination through the head impulse test as a diagnostic method for vestibular dysfunction as well as, and primarily, a bedside semiotic resource capable of differentiating between acute peripheral vestibulopathy and a cerebellar or brainstem infarction in emergency rooms.

Maranhão ET; Maranhão-Filho P

2012-12-01

370

Hysteresis-free reactive high power impulse magnetron sputtering  

Digital Repository Infrastructure Vision for European Research (DRIVER)

High power impulse magnetron sputtering (HIPIMS) of an Al target in Ar/O2 mixtures has been studied. The use of HIPIMS is shown to drastically influence the process characteristics compared to conventional sputtering. Under suitable conditions, oxide formation on the target as the reactive gas flow ...

Wallin, Erik; Helmersson, Ulf

371

What is Impulse Buying? An analytical network processing framework for prioritizing factors affecting impulse buying  

Directory of Open Access Journals (Sweden)

Full Text Available One of the most important issues affecting profitability is to determine the impact of different factors influencing purchasing activities. In this paper, we perform an extensive literature survey to detect different purchasing factors influencing customers' behavior. The factors are categorized in three different groups and they are ranked using analytical network process. The results of our survey indicate that three factors of personal, product and situational play important roles in purchasing impulse. The personal item includes different factors where demographic characteristic factors receive the highest ranking (35%) followed by other factors are feelings, excitement and fun, self identify, education and novelty. There are also three sub-factors associated with demographic characteristics including gender, age and race and the weights are 0.46748, 0.42668 and 0.10584, respectively, which means gender is the most important factor followed by age and race. Finally, the other factor is associated with situational factors' group, which includes presence of others, culture, design of store, time available, local market condition, sales staff and self service with the relative importance of 0.04296, 0.08733, 0.12130, 0.22217, 0.05643, 0.15346 and 0.31635, respectively.

Sahel Ehsani Masouleh; Marzieh Pazhang; Javad Siahkali Moradi

2012-01-01

372

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

1999-01-01

373

Sex modulates approach systems and impulsivity in substance dependence.  

Science.gov (United States)

BACKGROUND: Personality traits such as pathological engagement in approach behaviors, high levels of impulsivity and heightened negative affect are consistently observed in substance dependent individuals (SDI). The clinical course of addiction has been shown to differ between sexes. For example, women increase their rates of consumption of some drugs of abuse more quickly than men. Despite the potential influence of personality and sex on features of addiction, few studies have investigated the interaction of these factors in substance dependence. METHODS: Fifty-one SDI (26 males, 25 females) and 66 controls (41 males, 25 females) completed the Behavioral Inhibition/Behavioral Activation System (BIS/BAS) Scales, the Barratt Impulsiveness Scale, and the Positive and Negative Affect Schedule (PANAS-X). Data were analyzed with 2×2 ANCOVAs testing for main effects of group, sex and group by sex interactions, adjusting for education level. RESULTS: Significant group by sex interactions were observed for BAS scores [F(1,116)=7.03, p<.01] and Barratt Motor Impulsiveness [F(1,116)=6.11, p<.02] with female SDI showing the highest approach tendencies and impulsivity followed by male SDI, male controls, and finally female controls. SDI scored higher on negative affect [F(1,116)=25.23, p<.001] than controls. Behavioral Inhibition System scores were higher in women than men [F(1,116)=14.03, p<.001]. CONCLUSION: Higher BAS and motor impulsivity in SDI women relative to SDI men and control women suggest that personality traits that have been previously associated with drug use may be modulated by sex. These factors may contribute to differences in the disease course observed in male compared to female drug users. PMID:23725607

Perry, Robert I; Krmpotich, Theodore; Thompson, Laetitia L; Mikulich-Gilbertson, Susan K; Banich, Marie T; Tanabe, Jody

2013-05-28

374

Sex modulates approach systems and impulsivity in substance dependence.  

UK PubMed Central (United Kingdom)

BACKGROUND: Personality traits such as pathological engagement in approach behaviors, high levels of impulsivity and heightened negative affect are consistently observed in substance dependent individuals (SDI). The clinical course of addiction has been shown to differ between sexes. For example, women increase their rates of consumption of some drugs of abuse more quickly than men. Despite the potential influence of personality and sex on features of addiction, few studies have investigated the interaction of these factors in substance dependence. METHODS: Fifty-one SDI (26 males, 25 females) and 66 controls (41 males, 25 females) completed the Behavioral Inhibition/Behavioral Activation System (BIS/BAS) Scales, the Barratt Impulsiveness Scale, and the Positive and Negative Affect Schedule (PANAS-X). Data were analyzed with 2×2 ANCOVAs testing for main effects of group, sex and group by sex interactions, adjusting for education level. RESULTS: Significant group by sex interactions were observed for BAS scores [F(1,116)=7.03, p<.01] and Barratt Motor Impulsiveness [F(1,116)=6.11, p<.02] with female SDI showing the highest approach tendencies and impulsivity followed by male SDI, male controls, and finally female controls. SDI scored higher on negative affect [F(1,116)=25.23, p<.001] than controls. Behavioral Inhibition System scores were higher in women than men [F(1,116)=14.03, p<.001]. CONCLUSION: Higher BAS and motor impulsivity in SDI women relative to SDI men and control women suggest that personality traits that have been previously associated with drug use may be modulated by sex. These factors may contribute to differences in the disease course observed in male compared to female drug users.

Perry RI; Krmpotich T; Thompson LL; Mikulich-Gilbertson SK; Banich MT; Tanabe J

2013-05-01

375

Gambling severity, impulsivity, and psychopathology: comparison of treatment- and community-recruited pathological gamblers.  

UK PubMed Central (United Kingdom)

BACKGROUND AND OBJECTIVES: Because most studies of pathological gambling gather data from participants recruited from treatment, this study compared community and treatment-enrolled pathological gamblers (PGs) with respect to demographics, gambling severity, impulsivity, and psychopathology. METHODS: One hundred six PGs were recruited as part of two larger studies in Farmington, Connecticut (n= 61) and Windsor, Ontario (n= 45) using radio advertising, word of mouth, and/or newspaper ads, as well as a gambling treatment program at each location. RESULTS: Community (n= 49) and treatment-enrolled (n= 57) PGs did not differ on age, education, gender, race, employment, or marital status. Treatment-enrolled PGs were more likely to report past year illegal behaviors, preoccupation with gambling, and higher scores on the Barratt Impulsiveness Scale (BIS) Attention Impulsivity subscale. Assessment of psychopathology in the Ontario study indicated that treatment-enrolled PGs were more likely to present with Major Depressive and Dysthymic Disorders. Community-recruited PGs in the Connecticut study were overall more likely to present with any substance use disorder relative to their treatment-enrolled counterparts. CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE: Our findings inform intervention and research within the field of pathological gambling. Specifically, the distressing aspects of pathological gambling, such as legal issues, preoccupation with gambling, and depression, may be present more in treatment-enrolled PGs than in those recruited from the community. Such emotional disturbances should be further explored to increase motivation and treatment adherence in PGs. In addition, due to relative absence of overall differences between the groups, research findings utilizing treatment-enrolled PGs may be a good representation of both groups.

Knezevic B; Ledgerwood DM

2012-11-01

376

Effects of humoral factors on ventilation kinetics during recovery after impulse-like exercise.  

UK PubMed Central (United Kingdom)

To clarify the ventilatory kinetics during recovery after impulse-like exercise, subjects performed one impulse-like exercise test (one-impulse) and a five-times repeated impulse-like exercises test (five-impulse). Duration and intensity of the impulse-like exercise were 20 sec and 400 watts (80 rpm), respectively. Although blood pH during recovery (until 10 min) was significantly lower in the five-impulse test than in the one-impulse test, ventilation (.VE) in the two tests was similar except during the first 30 sec of recovery, in which it was higher in the five-impulse test. In one-impulse, blood CO2 pressure (PCO2) was significantly increased at 1 min during recovery and then returned to the pre-exercise level at 5 min during recovery. In the five-impulse test, PCO2 at 1 min during recovery was similar to the pre-exercise level, and then it decreased to a level lower than the pre-exercise level at 5 min during recovery. Accordingly, PCO2 during recovery (until 30 min) was significantly lower in the five-impulse than in one-impulse test..VE and pH during recovery showed a curvilinear relationship, and at the same pH, ventilation was higher in the one-impulse test. These results suggest that ventilatory kinetics during recovery after impulse-like exercise is attributed partly to pH, but the stimulatory effect of lower pH is diminished by the inhibitory effect of lower PCO2.

Afroundeh R; Arimitsu T; Yamanaka R; Lian C; Yunoki T; Yano T

2012-06-01

377

Determining attenuation of impulse noise with an electrical equivalent of a hearing protection device.  

UK PubMed Central (United Kingdom)

Determining the effectiveness of impulse noise attenuation with hearing protection devices (HPDs) is an important part of their selection. Measuring impulse noise parameters under an HPD would involve exposing subjects to impulses with a high peak sound pressure level. This paper presents a computational method of determining impulse noise parameters under the cups of earmuffs. Calculations are done using the transfer function of earmuffs, determined with Shaw's electrical equivalent of an HPD, taking into account the design parameters of earmuffs. The developed method was used for calculations in the presence of impulse noise generated by gunshots. To verify the computational method, the results of these calculations were compared with the results of measurements.

M?y?ski R; Koz?owski E

2013-01-01

378

Calculating the parameters of full lightning impulses using model-based curve fitting  

Energy Technology Data Exchange (ETDEWEB)

In this paper a brief review is presented of the techniques used for the evaluation of the parameters of high voltage impulses and the problems encountered. The determination of the best smooth curve through oscillations on a high voltage impulse is the major problem limiting the automatic processing of digital records of impulses. Non-linear regression, based on simple models, is applied to the analysis of simulated and experimental data of full lightning impulses. Results of model fitting to four different groups of impulses are presented and compared with some other methods. Plans for the extension of this work are outlined.

McComb, T.R.; Lagnese, J.E. (Electricity Div., National Inst. of Standards and Technology, Gaithersburg, MD (US))

1991-10-01

379

Calculating the parameters of full lightning impulses using model-based curve fitting  

International Nuclear Information System (INIS)

In this paper a brief review is presented of the techniques used for the evaluation of the parameters of high voltage impulses and the problems encountered. The determination of the best smooth curve through oscillations on a high voltage impulse is the major problem limiting the automatic processing of digital records of impulses. Non-linear regression, based on simple models, is applied to the analysis of simulated and experimental data of full lightning impulses. Results of model fitting to four different groups of impulses are presented and compared with some other methods. Plans for the extension of this work are outlined.

1991-01-01

380

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

CERN Multimedia

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

Berthe, Abdoulaye; Dragomirescu, Daniela; Plana, Robert

2010-01-01

 
 
 
 
381

Investigation of impulsivity in patients on dopamine agonist therapy for hyperprolactinemia: a pilot study.  

UK PubMed Central (United Kingdom)

The use of dopamine agonists (DAs) has been associated with increased impulsivity and impulse control disorders in several diseases, including Parkinson's disease. Such an effect of DAs on impulsivity has not been clearly characterized in hyperprolactinemic patients, where DAs are the mainstay of therapy. We studied the effects of DAs on impulsivity in hyperprolactinemic patients treated at a tertiary pituitary center, using validated psychometric tests. Cross-sectional study. Impulsivity was evaluated in 30 subjects, 10 hyperprolactinemic patients on DAs compared to two control groups; one comprising untreated hyperprolactinemic patients (n = 10) and a second group consisting of normoprolactinemic controls with pituitary lesions (n = 10). Measures of impulsivity included both self-report questionnaires as well as laboratory-based tasks. Hyperprolactinemic patients on DAs had a higher score (mean ± SD) in one self-report measure of impulsivity, the attention subscale of the Barratt Impulsiveness Scale (16.2 ± 2.7), as compared to the hyperprolactinemic control group (12.3 ± 2.5) and the normoprolactinemic group (14.7 ± 4.4) (p = 0.04). No statistically significant difference was found between groups with regards to the other impulsivity scales. In the DA-treated group, a correlation was observed between increased impulsivity (as assessed in the Experiential Discounting Task) and higher weekly cabergoline dose (r(2) = 0.49, p = 0.04). The use of DAs in hyperprolactinemic patients is associated with an increase in one aspect of impulsivity. This effect should be further characterized in larger, longitudinal studies.

Barake M; Evins AE; Stoeckel L; Pachas GN; Nachtigall LB; Miller KK; Biller BM; Tritos NA; Klibanski A

2013-03-01

382

Dimensions of impulsive behavior in obese, overweight, and healthy-weight adolescents.  

Science.gov (United States)

Impulsivity is a multidimensional construct that has been linked with obesity. To explore profiles of impulsive behavior potentially associated with adolescent weight status, we measured multiple dimensions of impulsivity (delay discounting, sustained attention, and behavioral disinhibition) using laboratory behavioral tasks in a sample of adolescents (N=61). For comparison purposes, we also assessed self-reported impulsive behavior with the BIS-11-A. Participants differed in body mass index: obese (n=21), overweight (n=20), and healthy-weight (n=20). Obese and overweight adolescents were more impulsive on the measure of delay discounting than healthy-weight adolescents, but no difference was found between obese and overweight adolescents on this measure. Obese adolescents also were more impulsive on the measure of inattention compared to overweight and healthy-weight adolescents, who did not differ on this measure. Behavioral disinhibition had no association with weight status, nor did the self-report measure of impulsivity. The additive pattern of these findings for certain laboratory behavioral measures indicates that obese adolescents are more impulsive than their healthy-weight counterparts on two dimensions of behavior, whereas overweight adolescents are more impulsive on only one dimension. Consequently, adolescents who are impulsive on two dimensions of behavior (i.e., delay discounting and sustained attention) may be at greater risk of becoming obese rather than overweight compared to adolescents who are impulsive on only one dimension of behavior (i.e., delay discounting). PMID:23831015

Fields, S A; Sabet, M; Reynolds, B

2013-07-04

383

Dimensions of impulsive behavior in obese, overweight, and healthy-weight adolescents.  

UK PubMed Central (United Kingdom)

Impulsivity is a multidimensional construct that has been linked with obesity. To explore profiles of impulsive behavior potentially associated with adolescent weight status, we measured multiple dimensions of impulsivity (delay discounting, sustained attention, and behavioral disinhibition) using laboratory behavioral tasks in a sample of adolescents (N=61). For comparison purposes, we also assessed self-reported impulsive behavior with the BIS-11-A. Participants differed in body mass index: obese (n=21), overweight (n=20), and healthy-weight (n=20). Obese and overweight adolescents were more impulsive on the measure of delay discounting than healthy-weight adolescents, but no difference was found between obese and overweight adolescents on this measure. Obese adolescents also were more impulsive on the measure of inattention compared to overweight and healthy-weight adolescents, who did not differ on this measure. Behavioral disinhibition had no association with weight status, nor did the self-report measure of impulsivity. The additive pattern of these findings for certain laboratory behavioral measures indicates that obese adolescents are more impulsive than their healthy-weight counterparts on two dimensions of behavior, whereas overweight adolescents are more impulsive on only one dimension. Consequently, adolescents who are impulsive on two dimensions of behavior (i.e., delay discounting and sustained attention) may be at greater risk of becoming obese rather than overweight compared to adolescents who are impulsive on only one dimension of behavior (i.e., delay discounting).

Fields SA; Sabet M; Reynolds B

2013-11-01

384

Environmental Stimulation Does Not Reduce Impulsive Choice in ADHD: A "Pink Noise" Study.  

UK PubMed Central (United Kingdom)

Objective: The preference for sooner smaller over larger later rewards is a prominent manifestation of impulsivity in ADHD. According to the State Regulation Deficit (SRD) model, this impulsive choice is the result of impaired regulation of arousal level and can be alleviated by adding environmental stimulation to increase levels of arousal. Method: To test this prediction, we studied the effects of adding background "pink noise" on impulsive choice using a classical and new adjusting choice delay task in a sample of 25 children with ADHD and 28 controls. Results: Children with ADHD made more impulsive choices than controls. Adding noise did not reduce impulsive choice in ADHD. Conclusion: The findings add to the existing evidence on impulsive choice in ADHD, but no evidence is found for the SRD model's explanation of this behavioral style. Alternative explanations for impulsive choice in ADHD are discussed. (J. of Att. Dis. 2013; XX(X) 1-XX).

Metin B; Roeyers H; Wiersema JR; van der Meere JJ; Gasthuys R; Sonuga-Barke E

2013-03-01

385

Impulsivity partially mediates the association between reduced working memory capacity and alcohol problems.  

UK PubMed Central (United Kingdom)

Although alcohol use disorders (AUDs) have been associated with impulsive personality traits and reduced working memory capacity (WMC), less is known about the nature of their interrelationships. This study was designed to test the hypothesis that low WMC is associated with both impulsive personality and alcohol problems, and that impulsive personality mediates the association between low WMC and alcohol problems. Measures of impulsive personality, WMC, and alcohol problems were assessed in a sample of young adults (N = 474), that varied widely in severity of alcohol problems, 57% of whom had alcohol dependence. Simple correlations revealed that WMC, impulsive personality traits, and alcohol problems were all significantly related. Structural equation models (SEMs) showed that impulsivity partially mediated the association between WMC and alcohol problems. Although directionality cannot be determined from these cross-sectional data, the results suggest that reduced WMC may promote impulsivity, which in turn, predisposes to alcohol problems.

Gunn RL; Finn PR

2013-02-01

386

Enhancing inhibition: How impulsivity and emotional activation interact with different implementation intentions.  

UK PubMed Central (United Kingdom)

Implementation intentions, a strategy in which a strong link is created between a cue and a to-be-performed action, have been shown to be efficacious in improving self-regulation. The relative efficacy of verbal and visual implementation intentions, however, has yet to be determined. Implementation intentions have also been shown to be inefficacious in participants with high impulsivity, specifically in individuals who reported having a high tendency to commit rash or regrettable actions as a result of intense affect (high urgency). Nevertheless, previous studies did not assess whether the individuals were in an emotional context at the time of the experiment. In the current study, we compared different forms of implementation intentions (verbal/visual/combined verbal-visual) on a computerized inhibition task while assessing impulsivity and emotional activation. The results showed that all types of implementation intentions improved inhibition performances significantly in participants with high urgency, but only when their emotional activation was low. There was no difference between the three types of implementation intentions.

Burkard C; Rochat L; Van der Linden M

2013-10-01

387

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

Directory of Open Access Journals (Sweden)

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

H Yurmiati; GA Wiedy; S Kusmajadi

2010-01-01

388

Impulsivity in bipolar disorder: relationships with neurocognitive dysfunction and substance use history.  

UK PubMed Central (United Kingdom)

OBJECTIVES: Impulsivity is a core feature in bipolar disorder. Although mood symptoms exacerbate impulsivity, self-reports of impulsivity are elevated, even during euthymia. Neurocognitive processes linked to impulsivity (e.g., attention, inhibition) are also impaired in patients with bipolar disorder, and a high frequency of comorbidities associated with impulsivity, such as substance use disorders, further highlights the clinical relevance of this dimension of the illness. Our objective was to assess the relationship between impulsivity and cognition in bipolar disorder. METHODS: We evaluated impulsivity in 98 patients with bipolar disorder and its relationship with symptoms, cognition, and substance use history. We assessed self-reports of trait impulsivity [Barrett Impulsiveness Scale (BIS)] and impulsive behaviors on the Iowa Gambling Task (IGT). A comprehensive clinical and neurocognitive battery was also completed. Patients were compared with 95 healthy controls. RESULTS: Patients with bipolar disorder had higher scores versus healthy controls on all BIS scales. Performance on the IGT was significantly impaired and patients showed a tendency toward more erratic choices. Depressive symptoms were positively correlated with trait impulsivity and with an increased tendency to attend more readily to losses versus gains on the IGT. We found no significant associations between impulsivity and neurocognition in the full bipolar sample; however, when sub-grouped based on substance abuse history, significant relationships were revealed only in subjects without a substance abuse history. CONCLUSIONS: Our data support prior reports of increased trait impulsivity and impairment on behavioral tasks of impulsiveness in bipolar disorder and suggest a differential relationship between these illness features that is dependent upon history of substance abuse.

Powers RL; Russo M; Mahon K; Brand J; Braga RJ; Malhotra AK; Burdick KE

2013-09-01

389

Experimental single-impulse magnetic focusing of launched cold atoms  

CERN Multimedia

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

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

2007-01-01

390

Review of Impulse Noise Removal from Digital Video  

Directory of Open Access Journals (Sweden)

Full Text Available With the advancement in communication and information technology, legacy system are replaced by high speed computer as a result of this the world is shifting from analog to digital systems. Now, it is possible to transmit the digital videos over a communication channel and vice versa. Color video processing systems are used for a variety of purposes ranging from capturing scenes, processing of frames for feature extraction etc. Digital videos are generally contaminated by noise. Impulse noise is one such noise which may corrupt the frames of a digital video during acquisition, transmission over a noisy channel or in storage etc. This paper discussed in details about the color video processing and various schemes for removal of impulse noise for digital video.

SHELEJ KHERA; RAVINDRA LUHACH

2013-01-01

391

A Device that can Produce Net Impulse Using Rotating Masses  

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes a device capable of producing net impulse, through two synchronized masses, which move along a figure-eight-shaped orbit. In addition to the detailed description of the mechanical components of this device, particular attention is paid to the theoretical treatment of the innovative principle on which the device is based. In more details, the mechanical system consists of two independent but simultaneous rotations, the former being related to the formation of the figure-eight-shaped path and the latter to an additional spinning. Based on the parametric equations of motion of the lumped masses, and considering semi-static tensile deformation of the connecting rods carrying them, it was found that the resultant impulse towards the direction of the spin vector includes a non-vanishing term that is linearly proportional to the time. In addition, reduced but encouraging experimental results are reported. These findings sustain the capability of the proposed mechanism to achieve propulsion.

Christopher G. Provatidis

2010-01-01

392

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.

Zhao Kaiyu; Yuan Zhaohui

2012-01-01

393

Impulse control disorders and dopaminergic treatments in Parkinson's disease.  

UK PubMed Central (United Kingdom)

A group of disorders sharing a failure to resist an impulse to perform a typically pleasurable activity that is finally harmful to the person or to others are known under the common denomination of impulse control disorders (ICDs). These behaviors, possibly previously neglected by lack of awareness, are increasingly reported among PD patients. Compelling evidence has stressed the relation between dopaminergic replacement and development of ICDs in PD, especially but not exclusively, with dopamine agonist therapy. Besides dopaminergic replacement, younger age, smoking habit, presence of familiar gambling problems and alcohol abuse can increase the risk. ICDs in PD may greatly affect patients and caregivers quality of life, stressing the importance of their screening. Management strategies include a careful use of dopaminergic therapy using the lowest effective doses.

Villa C; Pascual-Sedano B; Pagonabarraga J; Kulisevsky J

2011-11-01

394

Transient multiple impulsive signal analysis for pneumatic percussive rivet tools  

Science.gov (United States)

This paper presents a systematic study on the analysis of the multiple impulsive transient signals generated by the pneumatic percussive rivet tools, i.e. rivet hammers and bucking bars. Detailed discussions are provided on how to conduct vibration measurements of the tools and the methods of analysing the multiple impulsive signals. Important issues such as triggering method, averaging, windowing, recording, and conversion from fast Fourier transform narrow band spectrum to a one-third octave-band spectrum are included in the paper. In addition, the implementation of ISO 5349 standard on this type of measurement is addressed. It is believed that the methods presented in this paper can be applied for similar transient signals generated by other types of mechanical systems.

Cherng, John G.; Peng, Sheng-Lih

1994-01-01

395

Impulsivity Affects Suboptimal Gambling-Like Choice by Pigeons.  

UK PubMed Central (United Kingdom)

Pigeons prefer a low-probability, high-payoff but suboptimal alternative over a reliable low-payoff optimal alternative (i.e., one that results in more food). This finding is analogous to suboptimal human monetary gambling because in both cases there appears to be an overemphasis of the occurrence of the winning event (a jackpot) and an underemphasis of losing events. In the present research we found that pigeons chose suboptimally to the degree that they were impulsive as indexed by the steeper slope of the hyperbolic delay-discounting function (i.e., the shorter the delay they would accept in a smaller-sooner/larger-later procedure). These correlational findings have implications for the mechanisms underlying suboptimal choice by humans (e.g., problem gamblers) and they suggest that high baseline levels of impulsivity can enhance acquisition of a gambling habit. (PsycINFO Database Record (c) 2013 APA, all rights reserved).

Laude JR; Beckmann JS; Daniels CW; Zentall TR

2013-07-01

396

Observation of negative impulse velocity in free space  

CERN Document Server

Since the 1983 definition of the speed of light in vacuum as a fundamental constant with the exact value of 299792458 m/s the question remains as to what apart from the wavefront travels at that speed. It is commonly assumed that the entire wave-packet or an impulse of the electromagnetic radiation in free space does. Here it is shown, both theoretically and experimentally, that there exists a region close to the source, where, while the wave-front travels at the speed of light, the individual impulses comprising the body of the wave-packet appear to slow down and even go backwards in time. This three-dimensional near-field late-time effect may also explain some of the free-space superluminal measurements.

Budko, Neil V

2008-01-01

397

A suppression of an impulsive noise in ECG signal processing.  

UK PubMed Central (United Kingdom)

The biomedical signals are commonly recorded with a noise. Many different kinds of noise exist in biomedical environment. One of the noises is a waveform of an electrical activity of muscles. This "natural" distortion is usually modeled with a white Gaussian noise. But such assumption is not always true, because real-life muscle noise has sometimes impulsive character. First objective of this paper is an application of the alpha-stable distribution as a model of the real-life muscle noise in the ECG signal. Second objective of this paper is an application of a family of M-filters to suppression an impulsive noise in biomedical signals (ECG signals). The reference filter is the median filter.

Pander TP

2004-01-01

398

A suppression of an impulsive noise in ECG signal processing.  

Science.gov (United States)

The biomedical signals are commonly recorded with a noise. Many different kinds of noise exist in biomedical environment. One of the noises is a waveform of an electrical activity of muscles. This "natural" distortion is usually modeled with a white Gaussian noise. But such assumption is not always true, because real-life muscle noise has sometimes impulsive character. First objective of this paper is an application of the alpha-stable distribution as a model of the real-life muscle noise in the ECG signal. Second objective of this paper is an application of a family of M-filters to suppression an impulsive noise in biomedical signals (ECG signals). The reference filter is the median filter. PMID:17271747

Pander, T P

2004-01-01

399

Oscillation of a linear delay impulsive differential equation  

CERN Document Server

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\\geq0. Explicit oscillation results are presented.

Berezansky, L; Berezansky, L; Braverman, E

1995-01-01

400

[Repetitive impulse-associated behavioral disorders in Parkinson's disease].  

UK PubMed Central (United Kingdom)

Parkinson's disease (PD) is associated with a number of behavioral disorders which may cause considerable social, professional or financial problems. Impulse control disorders (ICDs), such as pathological gambling, binge eating, compulsive shopping and hypersexuality occur in approximately 13-14% of PD patients. Further behavioral disorders are the dopamine dysregulation syndrome (DDS), a substance dependence characterized by craving for dopaminergic substances and punding (prolonged repetitive activities which are not goal-oriented).Treatment-related risk factors are dopamine agonists for ICDs and a high total dopaminergic dose for DDS and punding. Shared risk factors are young age at onset, impulsive personality traits, depression and possibly dyskinesia. At the neuronal level these behavioral disorders seem to be associated with changes in the reward system and dysfunction of the orbitofrontal cortex. The evidence level for management strategies is at present insufficient. For ICDs current clinical practice consists of discontinuation or reduction of dopamine agonists.

Katzenschlager R; Goerlich KS; van Eimeren T

2012-12-01

 
 
 
 
401

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

402

Numerical method for impulse control of Piecewise Deterministic Markov Processes  

CERN Multimedia

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

de Saporta, Benoîte

2010-01-01

403

Luminescence spectra of zinc selenide during impulse irradiation with electrons  

Energy Technology Data Exchange (ETDEWEB)

Luminescence spectra of high-resistance zinc selenide during impulse irradiation by electrons are investigated. For the first time kinetics of luminescence drop is studied, on the basis of which the conclusion is drawn on the presence in samples of both, localised and non-localised centers. It has been found that in spite of the close impurities composition, zinc selenide samples may have different, by nature and intensity, luminescence centers.

Stel' makh, N.S.; Pirogova, G.N.; Glazunov, P.Ya.; Nepomnyashchij, O.N.; Ryabov, A.I. (AN SSSR, Moscow. Inst. Fizicheskoj Khimii)

1983-08-01

404

ASME code ductile failure criteria for impulsively loaded pressure vessels  

Energy Technology Data Exchange (ETDEWEB)

Ductile failure criteria suitable for application to impulsively loaded high pressure vessels that are designed to the rules of the ASME Code Section VI11 Division 3 are described and justified. The criteria are based upon prevention of load instability and the associated global failure mechanisms, and on protection against progressive distortion for multiple-use vessels. The criteria are demonstrated by the design and analysis of vessels that contain high explosive charges.

Nickell, Robert E.; Duffey, T. A. (Thomas A.); Rodriguez, E. A. (Edward A.)