Accuracy of the adiabatic-impulse approximation for closed and open quantum systems

NASA Astrophysics Data System (ADS)

Tomka, Michael; Campos Venuti, Lorenzo; Zanardi, Paolo

2018-03-01

We study the adiabatic-impulse approximation (AIA) as a tool to approximate the time evolution of quantum states when driven through a region of small gap. Such small-gap regions are a common situation in adiabatic quantum computing and having reliable approximations is important in this context. The AIA originates from the Kibble-Zurek theory applied to continuous quantum phase transitions. The Kibble-Zurek mechanism was developed to predict the power-law scaling of the defect density across a continuous quantum phase transition. Instead, here we quantify the accuracy of the AIA via the trace norm distance with respect to the exact evolved state. As expected, we find that for short times or fast protocols, the AIA outperforms the simple adiabatic approximation. However, for large times or slow protocols, the situation is actually reversed and the AIA provides a worse approximation. Nevertheless, we found a variation of the AIA that can perform better than the adiabatic one. This counterintuitive modification consists in crossing the region of small gap twice. Our findings are illustrated by several examples of driven closed and open quantum systems.

Photopions from nuclei in the distorted-wave impulse approximation

NASA Astrophysics Data System (ADS)

Girija, V.; Devanathan, V.

1982-11-01

The formalism for photoproduction of pions from nuclei has been developed in the distorted-wave impulse approximation, taking into account the effect of the change in pion momentum in nuclear medium. Detailed calculations have been done for the reaction 16O(γ, π+)16N for photon energies from 170 to 380 MeV, with a view to investigate the effect due to the gradient operator ∇-->π for momentum of the pion and test the sensitivity of the photopion cross sections to the details of the pion-nucleus optical potential. The results clearly establish that the gradient operator increases the cross sections throughout the energy region considered, the increase being small at lower energies. Also with ∇-->π, the cross sections are rendered less sensitive to the optical potential. The calculated differential cross sections agree very well with the recent experimental data of Shoda et al. for γ-ray energy of 200 MeV. However, the cross sections obtained at medium energies are higher when compared to the available experimental data. NUCLEAR REACTIONS π+ photoproduction from 16O; distorted wave impulse approximation; pion-nucleus optical potentials; gradient operator for the pion momentum.

Recursive inversion of externally defined linear systems by FIR filters

NASA Technical Reports Server (NTRS)

Bach, Ralph E., Jr.; Baram, Yoram

1989-01-01

The approximate inversion of an internally unknown linear system, given by its impulse response sequence, by an inverse system having a finite impulse response, is considered. The recursive least-squares procedure is shown to have an exact initialization, based on the triangular Toeplitz structure of the matrix involved. The proposed approach also suggests solutions to the problem of system identification and compensation.

Laboratory studies of scales for measuring helicopter noise

NASA Technical Reports Server (NTRS)

Ollerhead, J. B.

1982-01-01

The adequacy of the effective perceived noise level (EPNL) procedure for rating helicopter noise annoyance was investigated. Recordings of 89 helicopters and 30 fixed wing aircraft (CTOL) flyover sounds were rated with respect to annoyance by groups of approximately 40 subjects. The average annoyance scores were transformed to annoyance levels defined as the equally annoying sound levels of a fixed reference sound. The sound levels of the test sounds were measured on various scales, with and without corrections for duration, tones, and impulsiveness. On average, the helicopter sounds were judged equally annoying to CTOL sounds when their duration corrected levels are approximately 2 dB higher. Multiple regression analysis indicated that, provided the helicopter/CTOL difference of about 2 dB is taken into account, the particular linear combination of level, duration, and tone corrections inherent in EPNL is close to optimum. The results reveal no general requirement for special EPNL correction terms to penalize helicopter sounds which are particularly impulsive; impulsiveness causes spectral and temporal changes which themselves adequately amplify conventionally measured sound levels.

Theta-Pinch Thruster for Piloted Deep Space Exploration

NASA Technical Reports Server (NTRS)

LaPointe, Mike R.; Reddy, Dhanireddy (Technical Monitor)

2000-01-01

A new high-power propulsion concept that combines a rapidly pulsed theta-pinch discharge with upstream particle reflection by a magnetic mirror was evaluated under a Phase 1 grant awarded through the NASA Institute for Advanced Concepts. Analytic and numerical models were developed to predict the performance of a theta-pinch thruster operated over a wide range of initial gas pressures and discharge periods. The models indicate that a 1 m radius, 10 m long thruster operated with hydrogen propellant could provide impulse-bits ranging from 1 N-s to 330 N-s with specific impulse values of 7,500 s to 2,500 s, respectively. A pulsed magnetic field strength of 2 T is required to compress and heat the preionized hydrogen over a 10(exp -3) second discharge period, with about 60% of the heated plasma exiting the chamber each period to produce thrust. The unoptimized thruster efficiency is low, peaking at approximately 16% for an initial hydrogen chamber pressure of 100 Torr. The specific impulse and impulse-bit at this operating condition are 3,500 s and 90 N-s, respectively, and the required discharge energy is approximately 9x10(exp 6) J. For a pulse repetition rate of 10 Hz, the engine would produce an average thrust of 900 N at 3,500 s specific impulse. Combined with the electrodeless nature of the device, these performance parameters indicate that theta-pinch thrusters could provide unique, long-life propulsion systems for piloted deep space mission applications.

Effects of dopamine agonist dose and gender on the prognosis of impulse control disorders in Parkinson's disease.

PubMed

Joutsa, Juho; Martikainen, Kirsti; Vahlberg, Tero; Kaasinen, Valtteri

2012-12-01

Cross-sectional studies have demonstrated that Parkinson's disease patients have an increased risk of impulse control disorders, and that the disorders frequently co-exist with depressive symptoms. There have been no previous large-scale prospective studies investigating predictive and prognostic factors of these disorders. A population of 290 Parkinson's disease patients was studied at baseline and approximately 15 months later. The same screening methodology was used at both time-points (demographic and medication data together with the Questionnaire for Impulsive-compulsive Disorders in Parkinson's disease and the Beck Depression Inventory). The data was analyzed separating patients with and without impulse control disorders at baseline to obtain clinically useful prognostic factors. In patients who had impulse control disorders at baseline (n = 119), high dopamine agonist dose was associated with the presence of disorders at follow-up. Dopamine agonist levodopa equivalent daily dose over 160 mg was significantly associated with impulse control disorders with a positive predictive value of 92.5% (95% confidence interval 79.6%-98.4%). In addition, females had a better prognosis of impulse control disorders compared to males. The development of novel impulse control disorders (no disorder at baseline, disorder at follow-up) was associated with a concurrent increase in depression scores. The results suggest that dopamine agonist dose and gender are associated with the prognosis of impulse control disorders. Symptoms of depression emerge together with novel impulse control disorders in Parkinson's disease. Copyright © 2012 Elsevier Ltd. All rights reserved.

A useful approximation for the flat surface impulse response

NASA Technical Reports Server (NTRS)

Brown, Gary S.

1989-01-01

The flat surface impulse response (FSIR) is a very useful quantity in computing the mean return power for near-nadir-oriented short-pulse radar altimeters. However, for very small antenna beamwidths and relatively large pointing angles, previous analytical descriptions become very difficult to compute accurately. An asymptotic approximation is developed to overcome these computational problems. Since accuracy is of key importance, a condition is developed under which this solution is within 2 percent of the exact answer. The asymptotic solution is shown to be in functional agreement with a conventional clutter power result and gives a 1.25-dB correction to this formula to account properly for the antenna-pattern variation over the illuminated area.

Auditory and behavioral responses of California sea lions (Zalophus californianus) to single underwater impulses from an arc-gap transducer.

PubMed

Finneran, James J; Dear, Randall; Carder, Donald A; Ridgway, Sam H

2003-09-01

A behavioral response paradigm was used to measure underwater hearing thresholds in two California sea lions (Zalophus californianus) before and after exposure to underwater impulses from an arc-gap transducer. Preexposure and postexposure hearing thresholds were compared to determine if the subjects experienced temporary shifts in their masked hearing thresholds (MTTS). Hearing thresholds were measured at 1 and 10 kHz. Exposures consisted of single underwater impulses produced by an arc-gap transducer referred to as a "pulsed power device" (PPD). The electrical charge of the PPD was varied from 1.32 to 2.77 kJ; the distance between the subject and the PPD was varied over the range 3.4 to 25 m. No MTTS was observed in either subject at the highest received levels: peak pressures of approximately 6.8 and 14 kPa, rms pressures of approximately 178 and 183 dB re: 1 microPa, and total energy fluxes of 161 and 163 dB re: 1 microPa2s for the two subjects. Behavioral reactions to the tests were observed in both subjects. These reactions primarily consisted of temporary avoidance of the site where exposure to the PPD impulse had previously occurred.

Neuronal codes for the inhibitory control of impulsive actions in the rat infralimbic cortex.

PubMed

Tsutsui-Kimura, Iku; Ohmura, Yu; Izumi, Takeshi; Matsushima, Toshiya; Amita, Hidetoshi; Yamaguchi, Taku; Yoshida, Takayuki; Yoshioka, Mitsuhiro

2016-01-01

Poor impulse control is a debilitating condition observed in various psychiatric disorders and could be a risk factor for drug addiction, criminal involvement, and suicide. The rat infralimbic cortex (IL), located in the ventral portion of the medial prefrontal cortex, has been implicated in impulse control. To elucidate the neurophysiological basis of impulse control, we recorded single unit activity in the IL of a rat performing a 3-choiceserial reaction time task (3-CSRTT) and 2-choice task (2-CT), which are animal models for impulsivity. The inactivation of IL neuronal activity with an injection of muscimol (0.1 μg /side) disrupted impulse control in the 3-CSRTT. More than 60% (38/56) of isolated IL units were linked to impulse control, while approximately 30% of all units were linked to attentional function in the 3-CSRTT. To avoid confounding motor-related units with the impulse control-related units, we further conducted the 2-CT in which the animals' motor activities were restricted during recording window. More than 30% (14/44) of recorded IL units were linked to impulse control in the 2-CT. Several types of impulse control-related units were identified. Only 16% of all units were compatible with the results of the muscimol experiment, which showed a transient decline in the firing rate immediately before the release of behavioral inhibition. This is the first study to elucidate the neurophysiological basis of impulse control in the IL and to propose that IL neurons control impulsive actions in a more complex manner than previously considered. Copyright © 2015 Elsevier B.V. All rights reserved.

Ion radial diffusion in an electrostatic impulse model for stormtime ring current formation

NASA Technical Reports Server (NTRS)

Chen, Margaret W.; Schulz, Michael; Lyons, Larry R.; Gorney, David J.

1992-01-01

Guiding-center simulations of stormtime transport of ring-current and radiation-belt ions having first adiabatic invariants mu is approximately greater than 15 MeV/G (E is approximately greater than 165 keV at L is approximately 3) are surprisingly well described (typically within a factor of approximately less than 4) by the quasilinear theory of radial diffusion. This holds even for the case of an individual model storm characterized by substorm-associated impulses in the convection electric field, provided that the actual spectrum of the electric field is incorporated in the quasilinear theory. Correction of the quasilinear diffusion coefficient D(sub LL)(sup ql) for drift-resonance broadening (so as to define D(sub LL)(sup ql)) reduced the typical discrepancy with the diffusion coefficients D(sub LL)(sup sim) deduced from guiding-center simulations of representative-particle trajectories to a factor of approximately 3. The typical discrepancy was reduced to a factor of approximately 1.4 by averaging D(sub LL)(sup sim), D(sub LL)(sup ql), and D(sub LL)(sup rb) over an ensemble of model storms characterized by different (but statistically equivalent) sets of substorm-onset times.

Electric propulsion options for 10 kW class earth space missions

NASA Technical Reports Server (NTRS)

Patterson, M. J.; Curran, Francis M.

1989-01-01

Five and 10 kW ion and arcjet propulsion system options for a near-term space demonstration experiment have been evaluated. Analyses were conducted to determine first-order propulsion system performance and system component mass estimates. Overall mission performance of the electric propulsion systems was quantified in terms of the maximum thrusting time, total impulse, and velocity increment capability available when integrated onto a generic spacecraft under fixed mission model assumptions. Maximum available thrusting times for the ion-propelled spacecraft options, launched on a DELTA II 6920 vehicle, range from approximately 8,600 hours for a 4-engine 10 kW system to more than 29,600 hours for a single-engine 5 kW system. Maximum total impulse values and maximum delta-v's range from 1.2x10(7) to 2.1x10(7) N-s, and 3550 to 6200 m/s, respectively. Maximum available thrusting times for the arcjet propelled spacecraft launched on the DELTA II 6920 vehicle range from approximately 528 hours for the 6-engine 10 kW hydrazine system to 2328 hours for the single-engine 5 kW system. Maximum total impulse values and maximum delta-v's range from 2.2x10(6) to 3.6x10(6) N-s, and approximately 662 to 1072 m/s, respectively.

Approximating a free-field blast environment in the test section of an explosively driven conical shock tube

NASA Astrophysics Data System (ADS)

Stewart, J. B.

2018-02-01

This paper presents experimental data on incident overpressures and the corresponding impulses obtained in the test section of an explosively driven 10° (full angle) conical shock tube. Due to the shock tube's steel walls approximating the boundary conditions seen by a spherical sector cut out of a detonating sphere of energetic material, a 5.3-g pentolite shock tube driver charge produces peak overpressures corresponding to a free-field detonation from an 816-g sphere of pentolite. The four test section geometries investigated in this paper (open air, cylindrical, 10° inscribed square frustum, and 10° circumscribed square frustum) provide a variety of different time histories for the incident overpressures and impulses, with a circumscribed square frustum yielding the best approximation of the estimated blast environment that would have been produced by a free-field detonation.

Stormtime ring current and radiation belt ion transport: Simulations and interpretations

NASA Technical Reports Server (NTRS)

Lyons, Larry R.; Gorney, David J.; Chen, Margaret W.; Schulz, Michael

1995-01-01

We use a dynamical guiding-center model to investigate the stormtime transport of ring current and radiation-belt ions. We trace the motion of representative ions' guiding centers in response to model substorm-associated impulses in the convection electric field for a range of ion energies. Our simple magnetospheric model allows us to compare our numerical results quantitatively with analytical descriptions of particle transport, (e.g., with the quasilinear theory of radial diffusion). We find that 10-145-keV ions gain access to L approximately 3, where they can form the stormtime ring current, mainly from outside the (trapping) region in which particles execute closed drift paths. Conversely, the transport of higher-energy ions (approximately greater than 145 keV at L approximately 3) turns out to resemble radial diffusion. The quasilinear diffusion coefficient calculated for our model storm does not vary smoothly with particle energy, since our impulses occur at specific (although randomly determined) times. Despite the spectral irregularity, quasilinear theory provides a surprisingly accurate description of the transport process for approximately greater than 145-keV ions, even for the case of an individual storm. For 4 different realizations of our model storm, the geometric mean discrepancies between diffusion coefficients D(sup sim, sub LL) obtained from the simulations and the quasilinear diffusion coefficient D(sup ql, sub LL) amount to factors of 2.3, 2.3, 1.5, and 3.0, respectively. We have found that these discrepancies between D(sup sim, sub LL) and D(sup ql, sub LL) can be reduced slightly by invoking drift-resonance broadening to smooth out the sharp minima and maxima in D(sup ql, sub LL). The mean of the remaining discrepancies between D(sup sim, sub LL) and D(sup ql, sub LL) for the 4 different storms then amount to factors of 1.9, 2.1, 1.5, and 2.7, respectively. We find even better agreement when we reduce the impulse amplitudes systematically in a given model storm (e.g., reduction of all the impulse amplitudes by half reduces the discrepancy factor by at least its square root) and also when we average our results over an ensemble of 20 model storms (agreement is within a factor of 1.2 without impulse-amplitude reduction). We use our simulation results also to map phase-space densities f in accordance with Liouville's theorem. We find that the stormtime transport of approximately greater than 145-keV ions produces little change in f-bar the drift-averaged phase-space density on any drift shell of interest. However, the stormtime transport produces a major enhancement from the pre-storm phase-space density at energies approximately 30-145 keV, which are representative of the stormtime ring current.

Increased self-reported impulsivity in methamphetamine users maintaining drug abstinence.

PubMed

Jones, Hannah W; Dean, Andy C; Price, Kimberly A; London, Edythe D

2016-09-01

Impulsivity has been proposed as an important factor in the initiation and maintenance of addiction. Indirect evidence suggests that some methamphetamine users report less impulsivity when they are using methamphetamine compared to when abstaining from drug use, but this hypothesis has not been directly tested. In this study, self-reports of impulsivity were obtained from 32 methamphetamine-dependent (DSM-IV) research participants and 41 healthy control subjects, using the Barratt Impulsiveness Scale-11. The methamphetamine users were assessed during an active period of methamphetamine use, as determined through urinalysis, and again after approximately 1 week of confirmed abstinence. Control subjects likewise completed two assessments. A subset of participants also completed serial assessments of the Beck Depression Inventory (Methamphetamine Group, N = 17, Control Group, N = 38) and the Methamphetamine Withdrawal Questionnaire (Methamphetamine Group, N = 12). There was a significant interaction of group with time on impulsivity (p = 0.044), reflecting a significant increase from the first to the second assessment in the methamphetamine users (p = 0.013), but no change among healthy control subjects. In contrast, depressive and withdrawal symptoms significantly decreased between the first and second assessments in the methamphetamine users (ps ≤0.01). Change in impulsivity in methamphetamine users was not significantly correlated with change in withdrawal or depression (ps >0.05). These findings suggest that methamphetamine users report more impulsivity when abstaining from drug use, an effect that is not significantly related to methamphetamine withdrawal. Attenuation of impulsivity may reinforce continued methamphetamine use in these individuals.

Screening for impulse control symptoms in patients with de novo Parkinson disease

PubMed Central

Papay, Kimberly; Siderowf, Andrew

2013-01-01

Objective: To determine the frequency and correlates of impulse control and related behavior symptoms in patients with de novo, untreated Parkinson disease (PD) and healthy controls (HCs). Methods: The Parkinson's Progression Markers Initiative is an international, multisite, case-control clinical study conducted at 21 academic movement disorders centers. Participants were recently diagnosed, untreated PD patients (n = 168) and HCs (n = 143). The outcome measures were presence of current impulse control and related behavior symptoms based on recommended cutoff points for the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease (QUIP)-Short Form. Results: There were 311 participants with complete QUIP data. Frequencies of impulse control and related behavior symptoms for patients with PD vs HCs were as follows: gambling (1.2% vs 0.7%), buying (3.0% vs 2.1%), sexual behavior (4.2% vs 3.5%), eating (7.1% vs 10.5%), punding (4.8% vs 2.1%), hobbyism (5.4% vs 11.9%), walkabout (0.6% vs 0.7%), and any impulse control or related behavior (18.5% vs 20.3%). In multivariable models, a diagnosis of PD was not associated with symptoms of any impulse control or related behavior (p ≥ 0.10 in all cases). Conclusions: PD itself does not seem to confer an increased risk for development of impulse control or related behavior symptoms, which further reinforces the reported association between PD medications and impulse control disorders in PD. Given that approximately 20% of patients with newly diagnosed PD report some impulse control or related behavior symptoms, long-term follow-up is needed to determine whether such patients are at increased risk for impulse control disorder development once PD medications are initiated. PMID:23296128

Screening for impulse control symptoms in patients with de novo Parkinson disease: a case-control study.

PubMed

Weintraub, Daniel; Papay, Kimberly; Siderowf, Andrew

2013-01-08

To determine the frequency and correlates of impulse control and related behavior symptoms in patients with de novo, untreated Parkinson disease (PD) and healthy controls (HCs). The Parkinson's Progression Markers Initiative is an international, multisite, case-control clinical study conducted at 21 academic movement disorders centers. Participants were recently diagnosed, untreated PD patients (n = 168) and HCs (n = 143). The outcome measures were presence of current impulse control and related behavior symptoms based on recommended cutoff points for the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease (QUIP)-Short Form. There were 311 participants with complete QUIP data. Frequencies of impulse control and related behavior symptoms for patients with PD vs HCs were as follows: gambling (1.2% vs. 0.7%), buying (3.0% vs. 2.1%), sexual behavior (4.2% vs. 3.5%), eating (7.1% vs. 10.5%), punding (4.8% vs. 2.1%), hobbyism (5.4% vs. 11.9%), walkabout (0.6% vs. 0.7%), and any impulse control or related behavior (18.5% vs. 20.3%). In multivariable models, a diagnosis of PD was not associated with symptoms of any impulse control or related behavior (p ≥ 0.10 in all cases). PD itself does not seem to confer an increased risk for development of impulse control or related behavior symptoms, which further reinforces the reported association between PD medications and impulse control disorders in PD. Given that approximately 20% of patients with newly diagnosed PD report some impulse control or related behavior symptoms, long-term follow-up is needed to determine whether such patients are at increased risk for impulse control disorder development once PD medications are initiated.

Relativistic impulse approximation analysis of unstable calcium isotopes: {sup 60-74}Ca

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaki, K.

2009-06-15

Recent relativistic mean-field calculations have provided nuclear distributions of Ca isotopes whose mass numbers are 60 through 74. We calculate observables of proton elastic scattering from these unstable isotopes and discuss relations between observables and nuclear distributions of such unstable nuclei. The calculations are based on relativistic impulse approximation (RIA) at incident proton energies from 100 through 500 MeV where predictions of RIA have been shown to provide good agreement with experimental data. To validate the use of optimal factorization and first-order calculations at these energies, contributions from the Fermi motion of the target nuclei and multiple scattering are estimatedmore » and compared with results calculated without these effects.« less

Prompt particle acceleration around moving X-point magnetic field during impulsive phase of solar flares

NASA Technical Reports Server (NTRS)

Sakai, Jun-Ichi

1992-01-01

We present a model for high-energy solar flares to explain prompt proton and electron acceleration, which occurs around moving X-point magnetic field during the implosion phase of the current sheet. We derive the electromagnetic fields during the strong implosion phase of the current sheets, which is driven by the converging flow derived from the magnetohydrodynamic equations. It is shown that both protons and electrons can be promptly (within 1 second) accelerated to approximately 70 MeV and approximately 200 MeV, respectively. This acceleration mechanism can be applicable for the impulsive phase of the gradual gamma ray and proton flares (gradual GR/P flare), which have been called two-ribbon flares.

Ultrawideband radar clutter measurements and analysis

NASA Astrophysics Data System (ADS)

Tuley, Michael T.; Sheen, David M.; Collins, H. D.; Sager, Earl V.; Schultheis, A. C.

1993-05-01

This paper reports the results of ultrawideband radar clutter measurements made by Battelle- Pacific Northwest Laboratories and the System Planning Corporation near Sequim, WA. The measurement area is a mountainous coniferous forest with occasional roads and clear-cut areas. Local grazing angles range from near zero to approximately 40 degree(s). Very limited data are also presented from measurements made in a desert-type terrain near Richland, WA. Two ultrawideband radar systems were employed in the data collection. An impulse system providing an approximate one nanosecond monocycle pulse (bandwidth of 300 MHz - 1000 MHz) acquired data over a 0.7 km2 area (121,000 resolution cells). A step chirp radar with the same total bandwidth as the impulse system collected data over a 6.2 km2 area (780,000 resolution cells), including the area sampled by the impulse system. Wideband TEM horn antennas (log-periodic antennas for the step chirp system) deployed on a 19 m horizontally scanned aperture were used for transmission and reception, providing a 1.5 degree(s) azimuth resolution at 300 MHz for both systems.

The distribution of the intervals between neural impulses in the maintained discharges of retinal ganglion cells.

PubMed

Levine, M W

1991-01-01

Simulated neural impulse trains were generated by a digital realization of the integrate-and-fire model. The variability in these impulse trains had as its origin a random noise of specified distribution. Three different distributions were used: the normal (Gaussian) distribution (no skew, normokurtic), a first-order gamma distribution (positive skew, leptokurtic), and a uniform distribution (no skew, platykurtic). Despite these differences in the distribution of the variability, the distributions of the intervals between impulses were nearly indistinguishable. These inter-impulse distributions were better fit with a hyperbolic gamma distribution than a hyperbolic normal distribution, although one might expect a better approximation for normally distributed inverse intervals. Consideration of why the inter-impulse distribution is independent of the distribution of the causative noise suggests two putative interval distributions that do not depend on the assumed noise distribution: the log normal distribution, which is predicated on the assumption that long intervals occur with the joint probability of small input values, and the random walk equation, which is the diffusion equation applied to a random walk model of the impulse generating process. Either of these equations provides a more satisfactory fit to the simulated impulse trains than the hyperbolic normal or hyperbolic gamma distributions. These equations also provide better fits to impulse trains derived from the maintained discharges of ganglion cells in the retinae of cats or goldfish. It is noted that both equations are free from the constraint that the coefficient of variation (CV) have a maximum of unity.(ABSTRACT TRUNCATED AT 250 WORDS)

Synchrotron cooling and annihilation of an E(+)-E(-) plasma: The radiation mechanism for the March 5, 1979 transient

NASA Technical Reports Server (NTRS)

Ramaty, R.; Lingenfelter, R. E.; Bussard, R. W.

1980-01-01

Positron-electron pair radiation is examined as a mechanism that could be responsible for the impulsive phase emission of the March 5, 1979 transient. Synchrotron cooling and subsequent annihilation of the pairs can account for the energy spectrum, the very high brightness, and the approximately 0.4 MeV feature observed from this transient, whose source is likely to be a neutron star in the supernova remnant N49 in the Large Magellanic Cloud. In this model, the observed radiation is produced in the skin layer of a hot, radiation dominated pair atmosphere, probably confined to the vicinity of the neutron star by a strong magnetic field. The width of this layer is only about 0.1 mm. In this layer, approximately 10 to the 12th power generations of pairs are formed (by photon-photon collisions), cooled and annihilated during the approximately 0.15 sec duration of the impulsive phase. The very large burst energy implied by the distance of the Large Magellanic Cloud, and its very rapid release, are unsolved problems. Nonetheless, the possibility of neutron star vibrations, which could transport the energy coherently to the surface, heat the atmosphere mechanically to a hot, pair-producing temperature, and have a characteristic damping time roughly equal to the duration of the impulsive phase are addressed.

Electric Propulsion Options for 10 kW Class Earth-Space Missions

NASA Technical Reports Server (NTRS)

Patterson, M. J.; Curran, Francis M.

1989-01-01

Five and 10 kW ion and arcjet propulsion system options for a near-term space demonstration experiment were evaluated. Analyses were conducted to determine first-order propulsion system performance and system component mass estimates. Overall mission performance of the electric propulsion systems was quantified in terms of the maximum thrusting time, total impulse, and velocity increment capability available when integrated onto a generic spacecraft under fixed mission model assumptions. Maximum available thrusting times for the ion-propelled spacecraft options, launched on a DELTA 2 6920 vehicle, range from approximately 8,600 hours for a 4-engine 10 kW system to more than 29,600 hours for a single-engine 5 kW system. Maximum total impulse values and maximum delta-v's range from 1.2x10 (exp 7) to 2.1x10 (exp 7) N-s, and 3550 to 6200 m/s, respectively. Maximum available thrusting times for the arcjet propelled spacecraft launched on the DELTA 2 6920 vehicle range from approximately 528 hours for the 6-engine 10 kW hydrazine system to 2328 hours for the single-engine 5 kW system. Maximum total impulse values and maximum delta-v's range from 2.2x10 (exp 6) to 3.6x10 (exp 6) N-s, and approximately 662 to 1072 m/s, respectively.

Does Drinking to Cope Explain Links Between Emotion-Driven Impulse Control Difficulties and Hazardous Drinking? A Longitudinal Test

PubMed Central

Watkins, Laura E.; Franz, Molly R.; DiLillo, David; Gratz, Kim L.; Messman-Moore, Terri L.

2016-01-01

Difficulty controlling impulsive behaviors when experiencing negative emotions is a prominent risk factor for hazardous alcohol use, and prior research suggests that drinking to cope may mediate this association. The present study examines this possibility prospectively in a sample of 490 young adult women between the ages of 18 and 25. Participants completed measures of emotion-driven impulse control difficulties, drinking to cope, and hazardous alcohol use at six time points over the course of approximately 20 months (i.e., one assessment every four months). Multilevel structural equation modeling revealed that drinking to cope fully mediated the relationship between emotion-driven impulse control difficulties and hazardous alcohol use when examining these relationships between individuals and partially mediated this relation when examining these relationships within individuals. These findings suggest that drinking to cope is a key mechanism in the relationship between emotion-driven impulse control difficulties and hazardous drinking. Results highlight the importance of targeting both emotion dysregulation and drinking to cope when treating young women for alcohol use problems. PMID:26502334

Impulsive Personality and Alcohol Use: Bidirectional Relations Over One Year

PubMed Central

Kaiser, Alison; Bonsu, Jacqueline A.; Charnigo, Richard J.; Milich, Richard; Lynam, Donald R.

2016-01-01

Objective: Impulsive personality traits have been found to be robust predictors of substance use and problems in both cross-sectional and longitudinal research. Studies examining the relations of substance use and impulsive personality over time indicate a bidirectional relation, where substance use is also predictive of increases in later impulsive personality. The present study sought to build on these findings by examining the bidirectional relations among the different impulsive personality traits assessed by the UPPS-P Impulsive Behavior Scale, with an interest in urgency (the tendency to act rashly when experiencing strong affect). Method: Participants were 525 first-year college students (48.0% male, 81.1% White), who completed self-report measures assessing personality traits and a structured interview assessing past and current substance use. Data collection took place at two different time points: the first occurred during the participants’ first year of college, and the second occurred approximately 1 year later. Bidirectional relations were examined using structural equation modeling. Results: Time 1 (T1) positive urgency predicted higher levels of alcohol use at Time 2 (T2), whereas T1 lack of perseverance predicted lower levels of alcohol use at T2. T1 alcohol use predicted higher levels of positive urgency, negative urgency, sensation seeking, and lack of premeditation at T2. Conclusions: Findings provide greater resolution in characterizing the bidirectional relation between impulsive personality traits and substance use. PMID:27172580

Energetic electrons in impulsive solar flares

NASA Technical Reports Server (NTRS)

Batchelor, D. A.

1984-01-01

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.

A method for calculating transient thrust and flow-rate levels for Mariner type attitude control nitrogen gas jets

NASA Technical Reports Server (NTRS)

Ferrera, J. D.

1972-01-01

The purpose of this report is to define and program the transient pneumatic flow equations necessary to determine, for a given set of conditions (geometry, pressures, temperatures, valve on time, etc.), the total nitrogen impulse and mass flow per pulse for the single pulsing of a Mariner type reaction control assembly valve. The rates of opening and closing of the valves are modeled, and electrical pulse durations from 20 to 100 ms are investigated. In developing the transient flow analysis, maximum use was made of the steady-state analysis. The impulse results are also compared to an equivalent square-wave impulse for both the Mariner Mars 1971 (MM'71) and Mariner Mars 1964 (MM'64) systems. It is demonstrated that, whereas in the MM'64 system, the actual impulse was as much as 56 percent higher than an assumed impulse (which is the product of the steady-state thrust and value on time i.e., the square wave), in the MM'71 system, these two values were in error in the same direction by only approximately 4 percent because of the larger nozzle areas and shorter valve stroke used.

Genetic support for the dual nature of attention deficit hyperactivity disorder: substantial genetic overlap between the inattentive and hyperactive-impulsive components.

PubMed

McLoughlin, Gráinne; Ronald, Angelica; Kuntsi, Jonna; Asherson, Philip; Plomin, Robert

2007-12-01

Attention deficit hyperactivity disorder (ADHD) is a common, complex and highly heritable disorder, characterised by inattentive, impulsive and overactive behaviour. Evidence for the heritability of ADHD measures in twin population samples has come from the analysis of total scores that combine inattentive and hyperactive-impulsive symptoms subscales. This study investigated, in a community sample, the aetiology of ADHD-like traits and the aetiological overlap between the two dimensions that define the ADHD disorder. Parents of 6,222 approximately 8-year-old twin pairs from the Twins Early Development Study (TEDS) population sample completed the two subscales of the Conners' 18-item DSMIV checklist, a screening instrument for ADHD symptoms. Both subscales were highly heritable (hyperactive-impulsive: 88%; inattentive: 79%). Bivariate genetic modelling indicated substantial genetic overlap between the two components; however, there were significant independent genetic effects. These findings suggest that many genes associated with the hyperactivity-impulsivity dimension will also be associated with the inattentive dimension but that there is significant genetic heterogeneity as well. These results provide genetic support for combining the two behavioural dimensions that define ADHD, but also suggest that some symptom-specific genes will also be identified.

On optimal infinite impulse response edge detection filters

NASA Technical Reports Server (NTRS)

Sarkar, Sudeep; Boyer, Kim L.

1991-01-01

The authors outline the design of an optimal, computationally efficient, infinite impulse response edge detection filter. The optimal filter is computed based on Canny's high signal to noise ratio, good localization criteria, and a criterion on the spurious response of the filter to noise. An expression for the width of the filter, which is appropriate for infinite-length filters, is incorporated directly in the expression for spurious responses. The three criteria are maximized using the variational method and nonlinear constrained optimization. The optimal filter parameters are tabulated for various values of the filter performance criteria. A complete methodology for implementing the optimal filter using approximating recursive digital filtering is presented. The approximating recursive digital filter is separable into two linear filters operating in two orthogonal directions. The implementation is very simple and computationally efficient, has a constant time of execution for different sizes of the operator, and is readily amenable to real-time hardware implementation.

Fast Spatial Resolution Analysis of Quadratic Penalized Least-Squares Image Reconstruction With Separate Real and Imaginary Roughness Penalty: Application to fMRI.

PubMed

Olafsson, Valur T; Noll, Douglas C; Fessler, Jeffrey A

2018-02-01

Penalized least-squares iterative image reconstruction algorithms used for spatial resolution-limited imaging, such as functional magnetic resonance imaging (fMRI), commonly use a quadratic roughness penalty to regularize the reconstructed images. When used for complex-valued images, the conventional roughness penalty regularizes the real and imaginary parts equally. However, these imaging methods sometimes benefit from separate penalties for each part. The spatial smoothness from the roughness penalty on the reconstructed image is dictated by the regularization parameter(s). One method to set the parameter to a desired smoothness level is to evaluate the full width at half maximum of the reconstruction method's local impulse response. Previous work has shown that when using the conventional quadratic roughness penalty, one can approximate the local impulse response using an FFT-based calculation. However, that acceleration method cannot be applied directly for separate real and imaginary regularization. This paper proposes a fast and stable calculation for this case that also uses FFT-based calculations to approximate the local impulse responses of the real and imaginary parts. This approach is demonstrated with a quadratic image reconstruction of fMRI data that uses separate roughness penalties for the real and imaginary parts.

Temporary shift in masked hearing thresholds in odontocetes after exposure to single underwater impulses from a seismic watergun.

PubMed

Finneran, James J; Schlundt, Carolyn E; Dear, Randall; Carder, Donald A; Ridgway, Sam H

2002-06-01

A behavioral response paradigm was used to measure masked underwater hearing thresholds in a bottlenose dolphin (Tursiops truncatus) and a white whale (Delphinapterus leucas) before and after exposure to single underwater impulsive sounds produced from a seismic watergun. Pre- and postexposure thresholds were compared to determine if a temporary shift in masked hearing thresholds (MTTS), defined as a 6-dB or larger increase in postexposure thresholds, occurred. Hearing thresholds were measured at 0.4, 4, and 30 kHz. MTTSs of 7 and 6 dB were observed in the white whale at 0.4 and 30 kHz, respectively, approximately 2 min following exposure to single impulses with peak pressures of 160 kPa, peak-to-peak pressures of 226 dB re 1 microPa, and total energy fluxes of 186 dB re 1 microPa2 x s. Thresholds returned to within 2 dB of the preexposure value approximately 4 min after exposure. No MTTS was observed in the dolphin at the highest exposure conditions: 207 kPa peak pressure, 228 dB re 1 microPa peak-to-peak pressure, and 188 dB re 1 microPa2 x s total energy flux.

Negative mood and interference control in nonsuicidal self-injury.

PubMed

Allen, Kenneth J D; Hooley, Jill M

2017-02-01

People who engage in nonsuicidal self-injury (NSSI) often report high levels of impulsivity. However, results from behavioral tasks measuring impulsivity have been mixed: those with a history of NSSI generally perform comparably to healthy controls. Recent research suggests, however, that people who self-injure have specific deficits in response inhibition to negative emotional stimuli. Here, we extend this work by testing whether negative mood impairs interference control in NSSI. 33 participants reporting a history of NSSI (approximately half in the past year) and 31 age- and gender-matched healthy controls completed the multi-source interference task before and after a written negative mood induction designed to increase feelings of worthlessness, guilt, and shame. After the induction, the NSSI group reported increased negative mood but did not show worse interference control. In other words, increased negative mood did not correspond to increased behavioral impulsivity in participants reporting NSSI. Consistent with past research, the NSSI and healthy control groups showed equivalent task performance. This study adds to evidence that NSSI is not characterized by behavioral impulsivity, even in the context of negative mood. Copyright © 2016 Elsevier Inc. All rights reserved.

The Subthalamic Nucleus, Limbic Function, and Impulse Control.

PubMed

Rossi, P Justin; Gunduz, Aysegul; Okun, Michael S

2015-12-01

It has been well documented that deep brain stimulation (DBS) of the subthalamic nucleus (STN) to address some of the disabling motor symptoms of Parkinson's disease (PD) can evoke unintended effects, especially on non-motor behavior. This observation has catalyzed more than a decade of research concentrated on establishing trends and identifying potential mechanisms for these non-motor effects. While many issues remain unresolved, the collective result of many research studies and clinical observations has been a general recognition of the role of the STN in mediating limbic function. In particular, the STN has been implicated in impulse control and the related construct of valence processing. A better understanding of STN involvement in these phenomena could have important implications for treating impulse control disorders (ICDs). ICDs affect up to 40% of PD patients on dopamine agonist therapy and approximately 15% of PD patients overall. ICDs have been reported to be associated with STN DBS. In this paper we will focus on impulse control and review pre-clinical, clinical, behavioral, imaging, and electrophysiological studies pertaining to the limbic function of the STN.

Qualitative analysis of MTEM response using instantaneous attributes

NASA Astrophysics Data System (ADS)

Fayemi, Olalekan; Di, Qingyun

2017-11-01

This paper introduces new technique for qualitative analysis of multi-transient electromagnetic (MTEM) earth impulse response over complex geological structures. Instantaneous phase and frequency attributes were used in place of the conventional common offset section for improved qualitative interpretation of MTEM data by obtaining more detailed information from the earth impulse response. The instantaneous attributes were used to describe the lateral variation in subsurface resistivity and the visible geological structure with respect to given offsets. Instantaneous phase attribute was obtained by converting the impulse response into a complex form using the Hilbert transform. Conversely, the polynomial phase difference (PPD) estimator was favored over the center finite difference (CFD) approximation method in calculating the instantaneous frequency attribute because it is computationally efficient and has the ability to give a smooth variation of the instantaneous frequency over a common offset section. The observed results from the instantaneous attributes were in good agreement with both the subsurface model used and the apparent resistivity section obtained from the MTEM earth impulse response. Hence, this study confirms the capability of both instantaneous phase and frequency attributes as highly effective tools for MTEM qualitative analysis.

Development and Characterization of High-Efficiency, High-Specific Impulse Xenon Hall Thrusters

NASA Technical Reports Server (NTRS)

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

2004-01-01

This dissertation presents research aimed at extending the efficient operation of 1600 s specific impulse Hall thruster technology to the 2000 to 3000 s range. Motivated by previous industry efforts and mission studies, the aim of this research was to develop and characterize xenon Hall thrusters capable of both high-specific impulse and high-efficiency operation. During the development phase, the laboratory-model NASA 173M Hall thrusters were designed and their performance and plasma characteristics were evaluated. Experiments with the NASA-173M version 1 (v1) validated the plasma lens magnetic field design. Experiments with the NASA 173M version 2 (v2) showed there was a minimum current density and optimum magnetic field topography at which efficiency monotonically increased with voltage. Comparison of the thrusters showed that efficiency can be optimized for specific impulse by varying the plasma lens. During the characterization phase, additional plasma properties of the NASA 173Mv2 were measured and a performance model was derived. Results from the model and experimental data showed how efficient operation at high-specific impulse was enabled through regulation of the electron current with the magnetic field. The electron Hall parameter was approximately constant with voltage, which confirmed efficient operation can be realized only over a limited range of Hall parameters.

The High Power Electric Propulsion (HiPEP) Ion Thruster

NASA Technical Reports Server (NTRS)

Foster, John E.; Haag, Tom; Patterson, Michael; Williams, George J., Jr.; Sovey, James S.; Carpenter, Christian; Kamhawi, Hani; Malone, Shane; Elliot, Fred

2004-01-01

Practical implementation of the proposed Jupiter Icy Moon Orbiter (JIMO) mission, which would require a total delta V of approximately 38 km/s, will require the development of a high power, high specific impulse propulsion system. Initial analyses show that high power gridded ion thrusters could satisfy JIMO mission requirements. A NASA GRC-led team is developing a large area, high specific impulse, nominally 25 kW ion thruster to satisfy both the performance and the lifetime requirements for this proposed mission. The design philosophy and development status as well as a thruster performance assessment are presented.

Personality and attempted suicide. Analysis of anger, aggression and impulsivity.

PubMed

Giegling, Ina; Olgiati, Paolo; Hartmann, Annette M; Calati, Raffaella; Möller, Hans-Jürgen; Rujescu, Dan; Serretti, Alessandro

2009-12-01

Suicide is one of the leading causes of death worldwide, mortality from suicide being approximately 2%. Attempted suicide appears to be a major risk factor for suicide completion. Anger, aggression and impulsivity are personality traits associated with suicide attempt. In this study we analysed a part of a previously reported sample in order to test anger, impulsivity and temperament/character scales as predictors of aggression and self-aggression in suicide attempters and to compare anger- and aggression-related traits between impulsive and premeditated suicide attempts as well as between violent and non-violent suicide methods. One-hundred-eleven consecutively admitted inpatients with a lifetime history of attempted suicide were assessed for anger (State-Trait Anger Expression Inventory, STAXI), aggression (Questionnaire for Measuring Factors of Aggression, FAF) and temperament/character (Temperament and Character Inventory, TCI). Higher aggression scores, as measured by FAF, were predicted by being male, meeting criteria for borderline personality disorder and having higher angry temperament scores as assessed by STAXI; low cooperativeness was also associated with aggression but not after controlling for STAXI scales. TCI dimensions associated with self-aggression were high harm avoidance, high impulsivity and low self-directedness; state anger, inwardly directed anger and inhibition of aggression were also predictors of self-aggression. In conclusion, impulsivity and harm avoidance have emerged as temperament dimensions independently associated with self-aggressive tendencies in personality. Such interactions could explain the correlation between temperament and suicidality but further research is needed. Anger and self-directedness appear to have some effects on suicide attempt.

Daily morphine administration increases impulsivity in rats responding under a 5‐choice serial reaction time task

PubMed Central

Maguire, DR; Henson, C

2016-01-01

Background and Purpose Repeated administration of a μ opioid receptor agonist can enhance some forms of impulsivity, such as delay discounting. However, it is unclear whether repeated administration alters motor impulsivity. Experimental Approach We examined the effects of acute administration of morphine and amphetamine prior to and during daily morphine administration in rats responding under a five‐choice serial reaction time task. Rats (n = 5) were trained to detect a brief flash of light presented randomly in one of five response holes; responding in the target hole delivered food, whereas responding in the wrong hole or responding prior to illumination of the target stimulus (premature response) initiated a timeout. Premature responding served as an index of motor impulsivity. Key Results Administered acutely, morphine (0.1–10 mg·kg−1, i.p.) increased omissions and modestly, although not significantly, premature responding without affecting response accuracy; amphetamine (0.1–1.78 mg·kg−1, i.p.) increased premature responding without changing omissions or response accuracy. After 3 weeks of 10 mg·kg−1·day−1 morphine, tolerance developed to its effects on omissions whereas premature responding increased approximately fourfold, compared with baseline. Effects of amphetamine were not significantly affected by daily morphine administration. Conclusions and Implications These data suggest that repeated administration of morphine increased effects of morphine on motor impulsivity, although tolerance developed to other effects, such as omissions. To the extent that impulsivity is a risk factor for drug abuse, repeated administration of μ opioid receptor agonists, for recreational or therapeutic purposes, might increase impulsivity and thus the risk for drug abuse. PMID:26776751

Theoretical Performance of Hydrogen-Oxygen Rocket Thrust Chambers

NASA Technical Reports Server (NTRS)

Sievers, Gilbert K.; Tomazic, William A.; Kinney, George R.

1961-01-01

Data are presented for liquid-hydrogen-liquid-oxygen thrust chambers at chamber pressures from 15 to 1200 pounds per square inch absolute, area ratios to approximately 300, and percent fuel from about 8 to 34 for both equilibrium and frozen composition during expansion. Specific impulse in vacuum, specific impulse, combustion-chamber temperature, nozzle-exit temperature, characteristic velocity, and the ratio of chamber-to-nozzle-exit pressure are included. The data are presented in convenient graphical forms to allow quick calculation of theoretical nozzle performance with over- or underexpansion, flow separation, and introduction of the propellants at various initial conditions or heat loss from the combustion chamber.

Determination of threshold and maximum operating electric stresses for selected high voltage insulations. Task 2: Investigation of oil-filled paper insulated cables

NASA Astrophysics Data System (ADS)

Sosnowski, M.; Eager, G. S., Jr.

1983-06-01

Threshold voltage of oil-impregnated paper insulated cables are investigaed. Experimental work was done on model cables specially manufactured for this project. The cables were impregnated with mineral and with synthetic oils. Standard impulse breakdown voltage tests and impulse voltage breakdown tests with dc prestressing were performed at room temperature and at 1000C. The most important result is the finding of very high level of threshold voltage stress for oil-impregnated paper insulated cables. This threshold voltage is approximately 1.5 times higher than the threshold voltage or crosslinked polyethylene insulated cables.

Fortran 4 program for two-impulse rendezvous analysis

NASA Technical Reports Server (NTRS)

Barling, W. H., Jr.; Brothers, W. J.; Darling, W. H., Jr.

1967-01-01

Program determines if rendezvous in near space is possible, and performs an analysis to determine the approximate required values of the magnitude and direction of two thrust applications of the upper stage of a rocket firing. The analysis is performed by using ordinary Keplerian mechanics.

Impulse propagation in the nocturnal boundary layer: analysis of the geometric component.

PubMed

Blom, Philip; Waxler, Roger

2012-05-01

On clear dry nights over flat land, a temperature inversion and stable nocturnal wind jet lead to an acoustic duct in the lowest few hundred meters of the atmosphere. An impulsive signal propagating in such a duct is received at long ranges from the source as an extended wave train consisting of a series of weakly dispersed distinct arrivals followed by a strongly dispersed low-frequency tail. The leading distinct arrivals have been previously shown to be well modeled by geometric acoustics. In this paper, the geometric acoustics approximation for the leading arrivals is investigated. Using the solutions of the eikonal and transport equations, travel times, amplitudes, and caustic structures of the distinct arrivals have been determined. The time delay between and relative amplitudes of the direct-refracted and single ground reflection arrivals have been investigated as parameters for an inversion scheme. A two parameter quadratic approximation to the effective sound speed profile has been fit and found to be in strong agreement with meteorological measurements from the time of propagation.

Mission and system optimization of nuclear electric propulsion vehicles for lunar and Mars missions

NASA Technical Reports Server (NTRS)

Gilland, James H.

1991-01-01

The detailed mission and system optimization of low thrust electric propulsion missions is a complex, iterative process involving interaction between orbital mechanics and system performance. Through the use of appropriate approximations, initial system optimization and analysis can be performed for a range of missions. The intent of these calculations is to provide system and mission designers with simple methods to assess system design without requiring access or detailed knowledge of numerical calculus of variations optimizations codes and methods. Approximations for the mission/system optimization of Earth orbital transfer and Mars mission have been derived. Analyses include the variation of thruster efficiency with specific impulse. Optimum specific impulse, payload fraction, and power/payload ratios are calculated. The accuracy of these methods is tested and found to be reasonable for initial scoping studies. Results of optimization for Space Exploration Initiative lunar cargo and Mars missions are presented for a range of power system and thruster options.

Derivative information recovery by a selective integration technique

NASA Technical Reports Server (NTRS)

Johnson, M. A.

1974-01-01

A nonlinear stationary homogeneous digital filter DIRSIT (derivative information recovery by a selective integration technique) is investigated. The spectrum of a quasi-linear discrete describing function (DDF) to DIRSIT is obtained by a digital measuring scheme. A finite impulse response (FIR) approximation to the quasi-linearization is then obtained. Finally, DIRSIT is compared with its quasi-linear approximation and with a standard digital differentiating technique. Results indicate the effects of DIRSIT on a wide variety of practical signals.

Computation of Nonlinear Hydrodynamic Loads on Floating Wind Turbines Using Fluid-Impulse Theory: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kok Yan Chan, G.; Sclavounos, P. D.; Jonkman, J.

2015-04-02

A hydrodynamics computer module was developed for the evaluation of the linear and nonlinear loads on floating wind turbines using a new fluid-impulse formulation for coupling with the FAST program. The recently developed formulation allows the computation of linear and nonlinear loads on floating bodies in the time domain and avoids the computationally intensive evaluation of temporal and nonlinear free-surface problems and efficient methods are derived for its computation. The body instantaneous wetted surface is approximated by a panel mesh and the discretization of the free surface is circumvented by using the Green function. The evaluation of the nonlinear loadsmore » is based on explicit expressions derived by the fluid-impulse theory, which can be computed efficiently. Computations are presented of the linear and nonlinear loads on the MIT/NREL tension-leg platform. Comparisons were carried out with frequency-domain linear and second-order methods. Emphasis was placed on modeling accuracy of the magnitude of nonlinear low- and high-frequency wave loads in a sea state. Although fluid-impulse theory is applied to floating wind turbines in this paper, the theory is applicable to other offshore platforms as well.« less

Auditory and behavioral responses of bottlenose dolphins (Tursiops truncatus) and a beluga whale (Delphinapterus leucas) to impulsive sounds resembling distant signatures of underwater explosions.

PubMed

Finneran, J J; Schlundt, C E; Carder, D A; Clark, J A; Young, J A; Gaspin, J B; Ridgway, S H

2000-07-01

A behavioral response paradigm was used to measure masked underwater hearing thresholds in two bottlenose dolphins and one beluga whale before and after exposure to impulsive underwater sounds with waveforms resembling distant signatures of underwater explosions. An array of piezoelectric transducers was used to generate impulsive sounds with waveforms approximating those predicted from 5 or 500 kg HBX-1 charges at ranges from 1.5 to 55.6 km. At the conclusion of the study, no temporary shifts in masked-hearing thresholds (MTTSs), defined as a 6-dB or larger increase in threshold over pre-exposure levels, had been observed at the highest impulse level generated (500 kg at 1.7 km, peak pressure 70 kPa); however, disruptions of the animals' trained behaviors began to occur at exposures corresponding to 5 kg at 9.3 km and 5 kg at 1.5 km for the dolphins and 500 kg at 1.9 km for the beluga whale. These data are the first direct information regarding the effects of distant underwater explosion signatures on the hearing abilities of odontocetes.

Testing the Impulsiveness of Solar Flare Heating through Analysis of Dynamic Atmospheric Response

NASA Astrophysics Data System (ADS)

Newton, E. K.; Emslie, A. G.; Mariska, J. T.

1996-03-01

One crucial test of a solar flare energy transport model is its ability to reproduce the characteristics of the atmospheric motions inferred from soft X-ray line spectra. Using a recently developed diagnostic, the velocity differential emission measure (VDEM), we can obtain from observations a physical measure of the amount of soft X-ray mitting plasma flowing at each velocity, v, and hence the total momentum of the upflowing plasma, without approximation or parametric fitting. We have correlated solar hard X-ray emission profiles by the Yohkoh Hard X-ray telescope with the mass and momentum histories inferred from soft X-ray line profiles observed by the Yohkoh Bragg crystal spectrometers. For suitably impulsive hard X-ray emission, an analysis of the hydrodynamic equations predicts a proportionality between the hard X-ray intensity and the second time derivative of the soft X-ray mitting plasma's momentum. This relationship is borne out by an analysis of 18 disk-center impulsive flares of varying durations, thereby lending support to the hypothesis that a prompt energy deposition mechanism, such as an energetic electron flux, is indeed responsible for the soft X-ray response observed in the rise phase of sufficiently impulsive solar flares.

SELENE Translunar Trajectory Reconfiguration Plan Provided for the Case of Main Engine Anomaly

NASA Technical Reports Server (NTRS)

Kawakatsu, Yasuhiro

2007-01-01

In this paper, the reconfiguration of translunar trajectory in case of main engine anomaly is investigated. The objectives of the trajectory design are to reduce the excessive velocity at the Lunar encounter as well as to reduce the total required Delta-v to complete the sequence. 3-impulse Hohmann transfer based trajectory is adopted and possible trajectories are categorized under 2-body approximation. The solutions obtained are applied to more sophisticated models (3-body approximation and 4-body) and yields feasible trajectory.

An efficient approach to ARMA modeling of biological systems with multiple inputs and delays

NASA Technical Reports Server (NTRS)

Perrott, M. H.; Cohen, R. J.

1996-01-01

This paper presents a new approach to AutoRegressive Moving Average (ARMA or ARX) modeling which automatically seeks the best model order to represent investigated linear, time invariant systems using their input/output data. The algorithm seeks the ARMA parameterization which accounts for variability in the output of the system due to input activity and contains the fewest number of parameters required to do so. The unique characteristics of the proposed system identification algorithm are its simplicity and efficiency in handling systems with delays and multiple inputs. We present results of applying the algorithm to simulated data and experimental biological data In addition, a technique for assessing the error associated with the impulse responses calculated from estimated ARMA parameterizations is presented. The mapping from ARMA coefficients to impulse response estimates is nonlinear, which complicates any effort to construct confidence bounds for the obtained impulse responses. Here a method for obtaining a linearization of this mapping is derived, which leads to a simple procedure to approximate the confidence bounds.

Hot under the collar: The impact of heat on game play.

PubMed

Young, Michael E; McCoy, Anthony W; Hutson, John P; Schlabach, Meredith; Eckels, Steven

2017-03-01

High temperatures have been documented to affect behavior in a variety of ways depending on the nature of the task. We extended this prior research by examining the effects of dynamically changing temperature on various aspects of performance in a video game task. In the span of approximately an hour, temperature was gradually increased, stayed constant for a period of time, and gradually decreased to baseline. The gaming task was a variation on one used to assess impulsivity in participants thus allowing the possibility of assessing the effects of temperature on impulsive choice. Rather than heat increasing impulsivity and thus decreasing wait times, participants showed increases in wait times as temperature increased which either suggests that participants were becoming more self-controlled under heat or that the documented negative impact of heat on motor functioning was dominating their performance. Importantly, the participant's sensitivity to the changing task requirements was not affected by changes in temperature. Copyright © 2016 Elsevier Ltd. All rights reserved.

An investigation of lower-extremity functional asymmetry for non-preferred able-bodied walking speeds

PubMed Central

RICE, JOHN; SEELEY, MATTHEW K.

2010-01-01

Functional asymmetry is an idea that is often used to explain documented bilateral asymmetries during able-bodied gait. Within this context, this idea suggests that the non-dominant and dominant legs, considered as whole entities, contribute asymmetrically to support and propulsion during walking. The degree of functional asymmetry may depend upon walking speed. The purpose of this study was to better understand the potential relationship between functional asymmetry and walking speed. Bilateral ground reaction forces (GRF) were measured for 20 healthy subjects who walked at nine different speeds: preferred, +10%, +20%, +30%, +40, −10%, −20%, −30%, and −40%. Contribution to support was determined to be the support impulse: the time integral of the vertical GRF during stance. Contribution to propulsion was determined to be the propulsion impulse: the time integral of the anterior-posterior GRF, while this force was directed forward. Repeated measures ANOVA (α = 0.05) revealed leg × speed interactions for normalized support (p = 0.001) and propulsion (p = 0.001) impulse, indicating that speed does affect the degree of functional asymmetry during gait. Post hoc comparisons (α = 0.05) showed that support impulse was approximately 2% greater for the dominant leg, relative to the non-dominant leg, for the −10%, −20%, and −40% speeds. Propulsion impulse was 12% greater for the dominant leg than for the non-dominant leg at the +20% speed. Speed does appear to affect the magnitude of bilateral asymmetry during walking, however, only the bilateral difference for propulsion impulse at one fast speed (+20%) was supportive of the functional asymmetry idea. PMID:27182346

Self-stimulation in the rat: quantitative characteristics of the reward pathway.

PubMed

Gallistel, C R

1978-12-01

Quantitative characteristics of the neural pathway that carries the reinforcing signal in electrical self-stimulation of the brain were established by finding which combinations of stimulation parameters give the same performance in a runway. The reward for each run was a train of evenly spaced monophasic cathodal pulses from a monopolar electrode. With train duration and pulse frequency held constant, the required current was a hyperbolic function of pulse duration, with chronaxie c approximately 1.5 msec. With pulse duration held constant, the required strength of the train (the charge delivered per second) was a hyperbolic function of train duration, with chronaxie C approximately 500 msec. To a first approximation, the values of c and C were independent of the choice either of train duration and pulse frequency or of pulse duration, respectively. Hence, the current intensity required by any choice of train duration, pulse frequency, and pulse duration dependent on only two basic parameters, c and C, and one quantity, Qi, the required impulse charge. These may reflect, respectively, current integration by directly excited neurons; temporal integration of neural activity by synaptic processes in a neural network; and the peak of the impulse response of the network, assuming that the network has linear dynamics and that the reward depends on the peak of the output of the network.

Image Processing, Coding, and Compression with Multiple-Point Impulse Response Functions.

NASA Astrophysics Data System (ADS)

Stossel, Bryan Joseph

1995-01-01

Aspects of image processing, coding, and compression with multiple-point impulse response functions are investigated. Topics considered include characterization of the corresponding random-walk transfer function, image recovery for images degraded by the multiple-point impulse response, and the application of the blur function to image coding and compression. It is found that although the zeros of the real and imaginary parts of the random-walk transfer function occur in continuous, closed contours, the zeros of the transfer function occur at isolated spatial frequencies. Theoretical calculations of the average number of zeros per area are in excellent agreement with experimental results obtained from computer counts of the zeros. The average number of zeros per area is proportional to the standard deviations of the real part of the transfer function as well as the first partial derivatives. Statistical parameters of the transfer function are calculated including the mean, variance, and correlation functions for the real and imaginary parts of the transfer function and their corresponding first partial derivatives. These calculations verify the assumptions required in the derivation of the expression for the average number of zeros. Interesting results are found for the correlations of the real and imaginary parts of the transfer function and their first partial derivatives. The isolated nature of the zeros in the transfer function and its characteristics at high spatial frequencies result in largely reduced reconstruction artifacts and excellent reconstructions are obtained for distributions of impulses consisting of 25 to 150 impulses. The multiple-point impulse response obscures original scenes beyond recognition. This property is important for secure transmission of data on many communication systems. The multiple-point impulse response enables the decoding and restoration of the original scene with very little distortion. Images prefiltered by the random-walk transfer function yield greater compression ratios than are obtained for the original scene. The multiple-point impulse response decreases the bit rate approximately 40-70% and affords near distortion-free reconstructions. Due to the lossy nature of transform-based compression algorithms, noise reduction measures must be incorporated to yield acceptable reconstructions after decompression.

Vergence-mediated modulation of the human horizontal vestibulo-ocular reflex is eliminated by a partial peripheral gentamicin lesion.

PubMed

Migliaccio, Americo A; Minor, Lloyd B; Carey, John P

2004-11-01

The angular vestibulo-ocular reflex normally has an increased response during vergence on a near target. Surgical unilateral vestibular deafferentation reduces the horizontal vestibulo-ocular reflex (VOR) in response to far target viewing and eliminates this vergence effect. Intratympanic gentamicin treatment reduces VOR gain during far viewing, but the reduction is less severe than that after unilateral vestibular deafferentation. We sought to determine how gentamicin would affect vergence-mediated modulation of the VOR. The VOR in response to passive head impulses in the horizontal plane while viewing a far (124 cm) or near (15 cm) target was evaluated in 11 subjects following intratympanic gentamicin treatment. Three of these subjects had also been tested immediately prior to receiving gentamicin. The impulses were low amplitude (approximately 20 degrees ), high velocity (approximately 150 degrees /s), high acceleration (approximately 3,000 degrees /s2) horizontal head rotations administered manually by the investigator. Binocular eye and head velocity were recorded using the scleral search coil technique. The VOR gain was defined as eye velocity divided by inverted head velocity. Prior to intratympanic gentamicin, the VOR gain during rotations to either side was symmetric and showed the same vergence-mediated increase. Following gentamicin, head impulses towards the untreated side yielded VOR gains of 0.91+/-0.12 while viewing a far target and 1.27+/-0.22 while viewing a near target, an increase of 33%. Head impulses towards the treated side produced a hypometric VOR with no increase between far and near viewing. The average latency of the VOR was 7.6+/-2.5 ms towards the untreated side for either near or far viewing and 20.7+/-13.1 ms towards the treated side for either near or far viewing. Our findings show that a peripheral lesion caused by gentamicin does not ablate the VOR but does eliminate a component of the vestibular signal that is necessary for vergence-mediated modulation of the VOR. Gentamicin has preferential toxicity for the hair cells in the central zone of the crista, where irregular afferents predominate. Our findings are consistent with the hypothesis that irregular afferents provide the necessary signal for vergence-mediated modulation of the VOR.

Event-related wave activity in the EEG provides new marker of ADHD.

PubMed

Alexander, David M; Hermens, Daniel F; Keage, Hannah A D; Clark, C Richard; Williams, Leanne M; Kohn, Michael R; Clarke, Simon D; Lamb, Chris; Gordon, Evian

2008-01-01

This study examines the utility of new measures of event-related spatio-temporal waves in the EEG as a marker of ADHD, previously shown to be closely related to the P3 ERP in an adult sample. Wave activity in the EEG was assessed during both an auditory Oddball and a visual continuous performance task (CPT) for an ADHD group ranging in age from 6 to 18 years and comprising mostly Combined and Inattentive subtypes, and for an age and gender matched control group. The ADHD subjects had less wave activity at low frequencies ( approximately 1 Hz) during both tasks. For auditory Oddball targets, this effect was shown to be related to smaller P3 ERP amplitudes. During CPT, the approximately 1 Hz wave activity in the ADHD subjects was inversely related to clinical and behavioral measures of hyperactivity and impulsivity. CPT wave activity at approximately 1 Hz was seen to "normalise" following treatment with stimulant medication. The results identify a deficit in low frequency wave activity as a new marker for ADHD associated with levels of hyperactivity and impulsivity. The marker is evident across a range of tasks and may be specific to ADHD. While lower approximately 1 Hz activity partly accounts for reduced P3 ERPs in ADHD, the effect also arises for tasks that do not elicit a P3. Deficits in behavioral inhibition are hypothesized to arise from underlying dysregulation of cortical inhibition.

Greater impulsivity is associated with decreased brain activation in obese women during a delay discounting task.

PubMed

Stoeckel, Luke E; Murdaugh, Donna L; Cox, James E; Cook, Edwin W; Weller, Rosalyn E

2013-06-01

Impulsivity and poor inhibitory control are associated with higher rates of delay discounting (DD), or a greater preference for smaller, more immediate rewards at the expense of larger, but delayed rewards. Of the many functional magnetic resonance imaging (fMRI) studies of DD, few have investigated the correlation between individual differences in DD rate and brain activation related to DD trial difficulty, with difficult DD trials expected to activate putative executive function brain areas involved in impulse control. In the current study, we correlated patterns of brain activation as measured by fMRI during difficult vs. easy trials of a DD task with DD rate (k) in obese women. Difficulty was defined by how much a reward choice deviated from an individual's 'indifference point', or the point where the subjective preference for an immediate and a delayed reward was approximately equivalent. We found that greater delay discounting was correlated with less modulation of activation in putative executive function brain areas, such as the middle and superior frontal gyri and inferior parietal lobule, in response to difficult compared to easy DD trials. These results support the suggestion that increased impulsivity is associated with deficient functioning of executive function areas of the brain.

Personal noise exposure assessment from small firearms

NASA Astrophysics Data System (ADS)

Kardous, Chucri A.; Murphy, William J.; Willson, Robert D.

2003-04-01

The National Institute for Occupational Safety and Health conducted noise exposure evaluations of law-enforcement personnel during firearms training at indoor and outdoor firing ranges. A representative cross section of weapons used by officers was measured. Shooters participated in live-fire exercise at an indoor firing range using three different weapons: a Beretta .400 caliber pistol, a Remington 12-gauge shotgun, and an M4 .223-caliber assault rifle. Indoor and outdoor measurements were obtained for the Smith and Wesson .357 pistol and Colt .450 and 9-mm pistols, the Glock .400 pistol, and the Heckler and Koch and Colt AR15 .223 rifles. Impulses were measured using a Bruel and Kjaer 4136 1/4-in. microphone and TASCAM digital audio tape recorder. Relevant impulse noise metrics were calculated. Peak levels ranged from 155 to 168 dB SPL. A-weighted equivalent levels ranged from 124 to 128 dBA. The contributions of the secondary weapon firings were approximately 1 to 9 dBA. Other parameters such as A/B durations, number and mixture of impulses, spectral content, energy, kurtosis, temporal spacing, and hearing protectors' effectiveness were examined. Comparisons of applicable damage risk criteria are presented. Further studies are needed to establish an occupational impulse noise damage risk criterion.

Development and characterization of high-efficiency, high-specific impulse xenon Hall thrusters

NASA Astrophysics Data System (ADS)

Hofer, Richard Robert

This dissertation presents research aimed at extending the efficient operation of 1600 s specific impulse Hall thruster technology to the 2000--3000 s range. While recent studies of commercially developed Hall thrusters demonstrated greater than 4000 s specific impulse, maximum efficiency occurred at less than 3000 s. It was hypothesized that the efficiency maximum resulted as a consequence of modern magnetic field designs, optimized for 1600 s, which were unsuitable at high-specific impulse. Motivated by the industry efforts and mission studies, the aim of this research was to develop and characterize xenon Hall thrusters capable of both high-specific impulse and high-efficiency operation. The research divided into development and characterization phases. During the development phase, the laboratory-model NASA-173M Hall thrusters were designed with plasma lens magnetic field topographies and their performance and plasma characteristics were evaluated. Experiments with the NASA-173M version 1 (v1) validated the plasma lens design by showing how changing the magnetic field topography at high-specific impulse improved efficiency. Experiments with the NASA-173M version 2 (v2) showed there was a minimum current density and optimum magnetic field topography at which efficiency monotonically increased with voltage. Between 300--1000 V, total specific impulse and total efficiency of the NASA-173Mv2 operating at 10 mg/s ranged from 1600--3400 s and 51--61%, respectively. Comparison of the thrusters showed that efficiency can be optimized for specific impulse by varying the plasma lens design. During the characterization phase, additional plasma properties of the NASA-173Mv2 were measured and a performance model was derived accounting for a multiply-charged, partially-ionized plasma. Results from the model based on experimental data showed how efficient operation at high-specific impulse was enabled through regulation of the electron current with the magnetic field. The decrease of efficiency due to multiply-charged ions was minor. Efficiency was largely determined by the current utilization, which suggested maximum Hall thruster efficiency has yet to be reached. The electron Hall parameter was approximately constant with voltage, decreasing from an average of 210 at 300 V to an average of 160 between 400--900 V, which confirmed efficient operation can be realized only over a limited range of Hall parameters.

A dynamical proximity analysis of interacting galaxy pairs

NASA Technical Reports Server (NTRS)

Chatterjee, Tapan K.

1990-01-01

Using the impulsive approximation to study the velocity changes of stars during disk-sphere collisions and a method due to Bottlinger to study the post collision orbits of stars, the formation of various types of interacting galaxies is studied as a function of the distance of closest approach between the two galaxies.

Analysis and design of ion thruster for large space systems

NASA Technical Reports Server (NTRS)

Poeschel, R. L.; Kami, S.

1980-01-01

Design analyses showed that an ion thruster of approximately 50 cm in diameter will be required to produce a thrust of 0.5 N using xenon or argon as propellants, and operating the thruster at a specific impulse of 3530 sec or 6076 sec respectively. A multipole magnetic confinement discharge chamber was specified.

Gap formation by inclined massive planets in locally isothermal three-dimensional discs

NASA Astrophysics Data System (ADS)

Chametla, Raúl O.; Sánchez-Salcedo, F. J.; Masset, F. S.; Hidalgo-Gámez, A. M.

2017-07-01

We study gap formation in gaseous protoplanetary discs by a Jupiter mass planet. The planet's orbit is circular and inclined relative to the mid-plane of the disc. We use the impulse approximation to estimate the gravitational tidal torque between the planet and the disc, and infer the gap profile. For low-mass discs, we provide a criterion for gap opening when the orbital inclination is ≤30°. Using the fargo3d code, we simulate the disc response to an inclined massive planet. The dependence of the depth and width of the gap obtained in the simulations on the inclination of the planet is broadly consistent with the scaling laws derived in the impulse approximation. Although we mainly focus on planets kept on fixed orbits, the formalism permits to infer the temporal evolution of the gap profile in the cases where the inclination of the planet changes with time. This study may be useful to understand the migration of massive planets on inclined orbit, because the strength of the interaction with the disc depends on whether a gap is opened or not.

Window-Based Channel Impulse Response Prediction for Time-Varying Ultra-Wideband Channels.

PubMed

Al-Samman, A M; Azmi, M H; Rahman, T A; Khan, I; Hindia, M N; Fattouh, A

2016-01-01

This work proposes channel impulse response (CIR) prediction for time-varying ultra-wideband (UWB) channels by exploiting the fast movement of channel taps within delay bins. Considering the sparsity of UWB channels, we introduce a window-based CIR (WB-CIR) to approximate the high temporal resolutions of UWB channels. A recursive least square (RLS) algorithm is adopted to predict the time evolution of the WB-CIR. For predicting the future WB-CIR tap of window wk, three RLS filter coefficients are computed from the observed WB-CIRs of the left wk-1, the current wk and the right wk+1 windows. The filter coefficient with the lowest RLS error is used to predict the future WB-CIR tap. To evaluate our proposed prediction method, UWB CIRs are collected through measurement campaigns in outdoor environments considering line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios. Under similar computational complexity, our proposed method provides an improvement in prediction errors of approximately 80% for LOS and 63% for NLOS scenarios compared with a conventional method.

Window-Based Channel Impulse Response Prediction for Time-Varying Ultra-Wideband Channels

PubMed Central

Al-Samman, A. M.; Azmi, M. H.; Rahman, T. A.; Khan, I.; Hindia, M. N.; Fattouh, A.

2016-01-01

This work proposes channel impulse response (CIR) prediction for time-varying ultra-wideband (UWB) channels by exploiting the fast movement of channel taps within delay bins. Considering the sparsity of UWB channels, we introduce a window-based CIR (WB-CIR) to approximate the high temporal resolutions of UWB channels. A recursive least square (RLS) algorithm is adopted to predict the time evolution of the WB-CIR. For predicting the future WB-CIR tap of window wk, three RLS filter coefficients are computed from the observed WB-CIRs of the left wk−1, the current wk and the right wk+1 windows. The filter coefficient with the lowest RLS error is used to predict the future WB-CIR tap. To evaluate our proposed prediction method, UWB CIRs are collected through measurement campaigns in outdoor environments considering line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios. Under similar computational complexity, our proposed method provides an improvement in prediction errors of approximately 80% for LOS and 63% for NLOS scenarios compared with a conventional method. PMID:27992445

Line-source excited impulsive EM field response of thin plasmonic metal films

NASA Astrophysics Data System (ADS)

Štumpf, Martin; Vandenbosch, Guy A. E.

2013-08-01

In this paper, reflection against and transmission through thin plasmonic metal films, basic building blocks of many plasmonic devices, are analytically investigated directly in the time domain for an impulsive electric and magnetic line-source excitation. The electromagnetic properties of thin metallic films are modeled via the Drude model. The problem is formulated with the help of approximate thin-sheet boundary conditions and the analysis is carried out using the Cagniard-DeHoop technique. Closed-form space-time expressions are found and discussed. The obtained time-domain analytical expressions reveal the existence of the phenomenon of transient oscillatory surface effects along a plasmonic metal thin sheet. Illustrative numerical examples of transmitted/reflected pulsed fields are provided.

Impulsive acceleration and scatter-free transport of about 1 MeV per nucleon ions in (He-3)-rich solar particle events

NASA Technical Reports Server (NTRS)

Mason, G. M.; Ng, C. K.; Klecker, B.; Green, G.

1989-01-01

Impulsive solar energetic particle (SEP) events are studied to: (1) describe a distinct class of SEP ion events observed in interplanetary space, and (2) test models of focused transport through detailed comparisons of numerical model prediction with the data. An attempt will also be made to describe the transport and scattering properties of the interplanetary medium during the times these events are observed and to derive source injection profiles in these events. ISEE 3 and Helios 1 magnetic field and plasma data are used to locate the approximate coronal connection points of the spacecraft to organize the particle anisotropy data and to constrain some free parameters in the modeling of flare events.

Pelvic kinematic method for determining vertical jump height.

PubMed

Chiu, Loren Z F; Salem, George J

2010-11-01

Sacral marker and pelvis reconstruction methods have been proposed to approximate total body center of mass during relatively low intensity gait and hopping tasks, but not during a maximum effort vertical jumping task. In this study, center of mass displacement was calculated using the pelvic kinematic method and compared with center of mass displacement using the ground-reaction force-impulse method, in experienced athletes (n = 13) performing restricted countermovement vertical jumps. Maximal vertical jumps were performed in a biomechanics laboratory, with data collected using an 8-camera motion analysis system and two force platforms. The pelvis center of mass was reconstructed from retro-reflective markers placed on the pelvis. Jump height was determined from the peak height of the pelvis center of mass minus the standing height. Strong linear relationships were observed between the pelvic kinematic and impulse methods (R² = .86; p < .01). The pelvic kinematic method underestimated jump height versus the impulse method, however, the difference was small (CV = 4.34%). This investigation demonstrates concurrent validity for the pelvic kinematic method to determine vertical jump height.

Impulse responses of visible phototubes used in National Ignition Facility neutron time of flight diagnostics.

PubMed

Datte, P S; Eckart, M; Moore, A S; Thompson, W; Vergel de Dios, G

2016-11-01

Neutron-induced visible scintillation in neutron time of flight (NToF) diagnostics at the National Ignition Facility (NIF) is measured with 40 mm single stage micro-channel plate photomultipliers and a 40 mm vacuum photodiode, outside the neutron line of sight. In NIF experiments with 14 MeV neutron yields above Y > 10 × 10 15 these tubes are configured to deliver of order 1 nC of charge in the nominally 5 ns NToF into a 50 Ω load. We have examined a number of 40 mm tubes manufactured by Photek Ltd. of St. Leonards on Sea, UK, to determine possible changes in the instrument impulse response as a function of signal charge delivered in 1 ns. Precision NToF measurements at approximately 20 m require that we characterize changes in the impulse response moments to <40 ps for the first central moment and ∼2% rms for the square root of the second central moment with ∼500 ps value. Detailed results are presented for three different diode configurations.

The Liquid Annular Reactor System (LARS) propulsion

NASA Technical Reports Server (NTRS)

Powell, James; Ludewig, Hans; Horn, Frederick; Lenard, Roger

1990-01-01

A concept for very high specific impulse (greater than 2000 seconds) direct nuclear propulsion is described. The concept, termed the liquid annular reactor system (LARS), uses liquid nuclear fuel elements to heat hydrogen propellant to very high temperatures (approximately 6000 K). Operating pressure is moderate (approximately 10 atm), with the result that the outlet hydrogen is virtually 100 percent dissociated to monatomic H. The molten fuel is contained in a solid container of its own material, which is rotated to stabilize the liquid layer by centripetal force. LARS reactor designs are described, together with neutronic and thermal-hydraulic analyses. Power levels are on the order of 200 megawatts. Typically, LARS designs use seven rotating fuel elements, are beryllium moderated, and have critical radii of approximately 100 cm (core L/D approximately equal to 1.5).

Development of a head-phantom and measurement setup for lightning effects.

PubMed

Machts, Rene; Hunold, Alexander; Leu, Carsten; Haueisen, Jens; Rock, Michael

2016-08-01

Direct lightning strikes to human heads lead to various effects ranging from Lichtenberg figures, over loss of consciousness to death. The evolution of the induced current distribution in the head is of great interest to understand the effect mechanisms. This work describes a technique to model a simplified head-phantom to investigate effects during direct lightning strike. The head-phantom geometry, conductive and dielectric parameters were chosen similar to that of a human head. Three layers (brain, skull, and scalp) were created for the phantom using agarose hydrogel doped with sodium chloride and carbon. The head-phantom was tested on two different impulse generators, which reproduce approximate lightning impulses. The effective current and the current distribution in each layer were analyzed. The biggest part of the current flowed through the brain layer, approx. 70 % in cases without external flashover. Approx. 23 % of the current flowed through skull layer and 6 % through the scalp layer. However, the current decreased within the head-phantom to almost zero after a complete flashover on the phantom occurred. The flashover formed faster with a higher impulse current level. Exposition time of current through the head decreases with a higher current level of the lightning impulse. This mechanism might explain the fact that people can survive a lightning strike. The experiments help to understand lightning effects on humans.

Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

NASA Astrophysics Data System (ADS)

Wang, Jun-Hua; Wang, Jin; Lu, Yan; Du, Mao-Hua; Han, Fu-Zhu

2015-01-01

The effects of single pulse energy on the properties of ceramic coating fabricated on a Ti-6Al-4V alloy via micro-arc oxidation (MAO) in aqueous solutions containing aluminate, phosphate, and some additives are investigated. The thickness, micro-hardness, surface and cross-sectional morphology, surface roughness, and compositions of the ceramic coating are studied using eddy current thickness meter, micro-hardness tester, JB-4C Precision Surface roughness meter, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Single pulse energy remarkably influences the ceramic coating properties. The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. The sizes of oxide particles, micro-pores and micro-cracks slightly increase with impulse width and single pulse energy. The main surface conversion products generated during MAO process in aqueous solutions containing aluminate are rutile TiO2, anatase TiO2, and a large amount of Al2TiO5. The effects of single pulse energy on the micro-hardness and phase composition of ceramic coating are not as evident as those of frequency and duty cycle.

Force-Velocity, Impulse-Momentum Relationships: Implications for Efficacy of Purposefully Slow Resistance Training

PubMed Central

Schilling, Brian K.; Falvo, Michael J.; Chiu, Loren Z.F.

2008-01-01

The purpose of this brief review is to explain the mechanical relationship between impulse and momentum when resistance exercise is performed in a purposefully slow manner (PS). PS is recognized by ~10s concentric and ~4-10s eccentric actions. While several papers have reviewed the effects of PS, none has yet explained such resistance training in the context of the impulse-momentum relationship. A case study of normal versus PS back squats was also performed. An 85kg man performed both normal speed (3 sec eccentric action and maximal acceleration concentric action) and PS back squats over a several loads. Normal speed back squats produced both greater peak and mean propulsive forces than PS action when measured across all loads. However, TUT was greatly increased in the PS condition, with values fourfold greater than maximal acceleration repetitions. The data and explanation herein point to superior forces produced by the neuromuscular system via traditional speed training indicating a superior modality for inducing neuromuscular adaptation. Key pointsAs velocity approaches zero, propulsive force approaches zero, therefore slow moving objects only require force approximately equal to the weight of the resistance.As mass is constant during resistance training, a greater impulse will result in a greater velocity.The inferior propulsive forces accompanying purposefully slow training suggest other methods of resistance training have a greater potential for adaptation. PMID:24149464

Modeling, Real-Time Estimation, and Identification of UWB Indoor Wireless Channels

DOE PAGES

Olama, Mohammed M.; Djouadi, Seddik M.; Li, Yanyan; ...

2013-01-01

Stochastic differential equations (SDEs) are used to model ultrawideband (UWB) indoor wireless channels. We show that the impulse responses for time-varying indoor wireless channels can be approximated in a mean-square sense as close as desired by impulse responses that can be realized by SDEs. The state variables represent the inphase and quadrature components of the UWB channel. The expected maximization and extended Kalman filter are employed to recursively identify and estimate the channel parameters and states, respectively, from online received signal strength measured data. Both resolvable and nonresolvable multipath received signals are considered and represented as small-scaled Nakagami fading. Themore » proposed models together with the estimation algorithm are tested using UWB indoor measurement data demonstrating the method’s viability and the results are presented.« less

A mini-cavity probe reactor.

NASA Technical Reports Server (NTRS)

Hyland, R. E.

1971-01-01

The mini-cavity reactor is a rocket engine concept which combines the high specific impulse from a central gaseous fueled cavity (0.6 m diam) and NERVA type fuel elements in a driver region that is external to a moderator-reflector zone to produce a compact light weight reactor. The overall dimension including a pressure vessel that is located outside of the spherical reactor is approximately 1.21 m in diameter. Specific impulses up to 2000 sec are obtainable for 220 to 890 N of thrust with pressures less than 1000 atm. Powerplant weights including a radiator for disposing of the power in the driver region are between 4600 and 32,000 kg - less than payloads of the shuttle. This reactor could also be used as a test reactor for gas-core, MHD, breeding and materials research.

Hormonal profile impact on female sexual function in young women

NASA Astrophysics Data System (ADS)

Stoian, Dana; Craciunescu, Mihalea; Craina, Marius; Pater, Liana; Pater, Flavius

2014-12-01

Female sexual function is dependent, in physiological milieu upon hormonal impulses: estradiol, testosterone, cortisol, progesterone, prolactin and TSH. Out study tries to appreciate the impact of testosterone, estradiol and prolactin, the major hormones involved in the sexual response, on the normal sexual function. This parameter is approximated by the value of the total FSFI score, a validated international structured interview.

A simple performance calculation method for LH2/LOX engines with different power cycles

NASA Technical Reports Server (NTRS)

Schmucker, R. H.

1973-01-01

A simple method for the calculation of the specific impulse of an engine with a gas generator cycle is presented. The solution is obtained by a power balance between turbine and pump. Approximate equations for the performance of the combustion products of LH2/LOX are derived. Performance results are compared with solutions of different engine types.

Power Spectral Density and Hilbert Transform

DTIC Science & Technology

2016-12-01

Fourier transform, Hilbert transform, digital filter , SDR 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER...terms. A very good approximation to the ideal Hilbert transform is a low-pass finite impulse response (FIR) filter . In Fig. 7, we show a real signal...220), converted to an analytic signal using a 255-tap Hilbert transform low-pass filter . For an ideal Hilbert

Airbreathing engine selection criteria for SSTO propulsion system

NASA Astrophysics Data System (ADS)

Ohkami, Yoshiaki; Maita, Masataka

1995-02-01

This paper presents airbreathing engine selection criteria to be applied to the propulsion system of a Single Stage To Orbit (SSTO). To establish the criteria, a relation among three major parameters, i.e., delta-V capability, weight penalty, and effective specific impulse of the engine subsystem, is derived as compared to these parameters of the LH2/LOX rocket engine. The effective specific impulse is a function of the engine I(sub sp) and vehicle thrust-to-drag ratio which is approximated by a function of the vehicle velocity. The weight penalty includes the engine dry weight, cooling subsystem weight. The delta-V capability is defined by the velocity region starting from the minimum operating velocity up to the maximum velocity. The vehicle feasibility is investigated in terms of the structural and propellant weights, which requires an iteration process adjusting the system parameters. The system parameters are computed by iteration based on the Newton-Raphson method. It has been concluded that performance in the higher velocity region is extremely important so that the airbreathing engines are required to operate beyond the velocity equivalent to the rocket engine exhaust velocity (approximately 4500 m/s).

Detecting the spatial chirp signals by fractional Fourier lens with transformation materials

NASA Astrophysics Data System (ADS)

Chen, J.; Hu, J.

2018-02-01

Fractional Fourier transform (FrFT) is the general form of the Fourier transform and is an important tool in signal processing. As one typical application of FrFT, detecting the chirp rate (CR, or known as the rate of frequency change) of a chirp signal is important in many optical measurements. The optical FrFT that based on graded index lens fails to detect the high CR chirp because the short wave propagation distance of the impulse in the lens will weaken the paraxial approximation condition. With the help of transformation optics, the improved FrFT lens is proposed to adjust the high CR as well as the impulse location of the given input chirp signal. The designed transformation materials can implement the effect of space compression, making the input chirp signal is equivalent to have lower CR, therefore the system can satisfy the paraxial approximation better. As a result, this lens can improve the detection precision for the high CR. The numerical simulations verified the design. The proposed device may have both theoretical and practical values, and the design demonstrates the ability and flexibility of TO in spatial signal processing.

Advanced Hydrocarbon Fuel Development

NASA Technical Reports Server (NTRS)

Bai, S. Don; Rodgers, Stephen L. (Technical Monitor)

2000-01-01

As a part of a high energy density materials (HEDM) development, the hot fire tests for Quadricyclane, 1,7 Octadiyne, AFRL-1, Biclopropylidene, and CINCH (Dimethyl amino ethyl azide) have been conducted at NASA/MSFC. The first 4 materials for this task are provided from Air Force Research Laboratory at Edward Air Force Base and US Army provided CINCH. The performance of these fuels is compared with RP-1. The preliminary results of these tests are presented. The preliminary results of Quadricyclane tests indicate that the specific impulse and c-star efficiency for quadricyclane at the mixture ratio 1.94 are approximately 5 sec and 105 ft/sec better than the RP-1 at mixture ratio 1.9. The 1,7 Octadiyne test indicate that the specific impulse and c-star efficiency at the mixture ratio 2.1 are approximately -1 sec and 89 ft/sec differ than the RP-1 at mixture ratio 2.04. The Quadricyclane soot buildup at the combustor is a little more than RP-1, but detail study of soot formation is not considered at this time. There was no visual soot buildup for the 1,7 Octadiyne and AFRL-1.

Strong potential wave functions with elastic channel distortion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Macek, J.; Taulbjerg, K.

1989-06-01

The strong-potential Born approximation is analyzed in a channel-distorted-wave approach. Channel-distorted SPB wave functions are reduced to a conventional form in which the standard off-energy-shell factor /ital g/ has been replaced by a modified factor ..gamma.., which represents a suitable average of /ital g/ over the momentum distribution of the distorted-channel function. The modified factor is evaluated in a physically realistic model for the distortion potential, and it is found that ..gamma.. is well represented by a slowly varying phase factor. The channel-distorted SPB approximation is accordingly identical to the impulse approximation if the phase variation of ..gamma.. can bemore » ignored. This is generally the case in applications to radiative electron capture and to a good approximation for ordinary capture at not too small velocities.« less

A Fast Method to Calculate the Spatial Impulse Response for 1-D Linear Ultrasonic Phased Array Transducers

PubMed Central

Zou, Cheng; Sun, Zhenguo; Cai, Dong; Muhammad, Salman; Zhang, Wenzeng; Chen, Qiang

2016-01-01

A method is developed to accurately determine the spatial impulse response at the specifically discretized observation points in the radiated field of 1-D linear ultrasonic phased array transducers with great efficiency. In contrast, the previously adopted solutions only optimize the calculation procedure for a single rectangular transducer and required approximation considerations or nonlinear calculation. In this research, an algorithm that follows an alternative approach to expedite the calculation of the spatial impulse response of a rectangular linear array is presented. The key assumption for this algorithm is that the transducer apertures are identical and linearly distributed on an infinite rigid plane baffled with the same pitch. Two points in the observation field, which have the same position relative to two transducer apertures, share the same spatial impulse response that contributed from corresponding transducer, respectively. The observation field is discretized specifically to meet the relationship of equality. The analytical expressions of the proposed algorithm, based on the specific selection of the observation points, are derived to remove redundant calculations. In order to measure the proposed methodology, the simulation results obtained from the proposed method and the classical summation method are compared. The outcomes demonstrate that the proposed strategy can speed up the calculation procedure since it accelerates the speed-up ratio which relies upon the number of discrete points and the number of the array transducers. This development will be valuable in the development of advanced and faster linear ultrasonic phased array systems. PMID:27834799

The neurobiology of impulse control disorders in Parkinson's disease: from neurotransmitters to neural networks.

PubMed

Vriend, Chris

2018-01-30

Impulse control disorders (ICD) are common neuropsychiatric disorders that can arise in Parkinson's disease (PD) patients after commencing dopamine replacement therapy. Approximately 15% of all patients develop these disorders and many more exhibit subclinical symptoms of impulsivity. ICD is thought to develop due to an interaction between the use of dopaminergic medication and an as yet unknown neurobiological vulnerability that either pre-existed before PD onset (possibly genetic) or is associated with neural alterations due to the PD pathology. This review discusses genes, neurotransmitters and neural networks that have been implicated in the pathophysiology of ICD in PD. Although dopamine and the related reward system have been the main focus of research, recently, studies have started to look beyond those systems to find new clues to the neurobiological underpinnings of ICD and come up with possible new targets for treatment. Studies on the whole-brain connectome to investigate the global alterations due to ICD development are currently lacking. In addition, there is a dire need for longitudinal studies that are able to disentangle the contributions of individual (genetic) traits and secondary effects of the PD pathology and chronic dopamine replacement therapy to the development of ICD in PD.

MHD Energy Bypass Scramjet Performance with Real Gas Effects

NASA Technical Reports Server (NTRS)

Park, Chul; Mehta, Unmeel B.; Bogdanoff, David W.

2000-01-01

The theoretical performance of a scramjet propulsion system incorporating an magneto-hydro-dynamic (MHD) energy bypass scheme is calculated. The one-dimensional analysis developed earlier, in which the theoretical performance is calculated neglecting skin friction and using a sudden-freezing approximation for the nozzle flow, is modified to incorporate the method of Van Driest for turbulent skin friction and a finite-rate chemistry calculation in the nozzle. Unlike in the earlier design, in which four ramp compressions occurred in the pitch plane, in the present design the first two ramp compressions occur in the pitch plane and the next two compressions occur in the yaw plane. The results for the simplified design of a spaceliner show that (1) the present design produces higher specific impulses than the earlier design, (2) skin friction substantially reduces thrust and specific impulse, and (3) the specific impulse of the MHD-bypass system is still better than the non-MHD system and typical rocket over a narrow region of flight speeds and design parameters. Results suggest that the energy management with MHD principles offers the possibility of improving the performance of the scramjet. The technical issues needing further studies are identified.

A control system design approach for flexible spacecraft

NASA Technical Reports Server (NTRS)

Silverberg, L. M.

1985-01-01

A control system design approach for flexible spacecraft is presented. The control system design is carried out in two steps. The first step consists of determining the ideal control system in terms of a desirable dynamic performance. The second step consists of designing a control system using a limited number of actuators that possess a dynamic performance that is close to the ideal dynamic performance. The effects of using a limited number of actuators is that the actual closed-loop eigenvalues differ from the ideal closed-loop eigenvalues. A method is presented to approximate the actual closed-loop eigenvalues so that the calculation of the actual closed-loop eigenvalues can be avoided. Depending on the application, it also may be desirable to apply the control forces as impulses. The effect of digitizing the control to produce the appropriate impulses is also examined.

A minimax technique for time-domain design of preset digital equalizers using linear programming

NASA Technical Reports Server (NTRS)

Vaughn, G. L.; Houts, R. C.

1975-01-01

A linear programming technique is presented for the design of a preset finite-impulse response (FIR) digital filter to equalize the intersymbol interference (ISI) present in a baseband channel with known impulse response. A minimax technique is used which minimizes the maximum absolute error between the actual received waveform and a specified raised-cosine waveform. Transversal and frequency-sampling FIR digital filters are compared as to the accuracy of the approximation, the resultant ISI and the transmitted energy required. The transversal designs typically have slightly better waveform accuracy for a given distortion; however, the frequency-sampling equalizer uses fewer multipliers and requires less transmitted energy. A restricted transversal design is shown to use the least number of multipliers at the cost of a significant increase in energy and loss of waveform accuracy at the receiver.

A finite element study of the EIDI system. [Electro-Impulse De-Icing System

NASA Technical Reports Server (NTRS)

Khatkhate, A. A.; Scavuzzo, R. J.; Chu, M. L.

1988-01-01

This paper presents a method for modeling the structural dynamics of an Electro-Impulse De-Icing System, using finite element analyses procedures. A guideline for building a representative finite element model is discussed. Modeling was done initially using four noded cubic elements, four noded isoparametric plate elements and eight noded isoparametric shell elements. Due to the size of the problem and due to the underestimation of shear stress results when compared to previous analytical work an approximate model was created to predict possible areas of shedding of ice. There appears to be good agreement with the test data provided by The Boeing Commercial Airplane Company. Thus these initial results of this method were found to be encouraging. Additional analytical work and comparison with experiment is needed in order to completely evaluate this approach.

Exclusive Meson Electroweak production off Bound Nucleons

NASA Astrophysics Data System (ADS)

Sato, Toru

2018-05-01

The effects of final state interaction in electroweak pion production reactions have been studied. The one loop corrections to the impulse approximation due to the nucleon and the pion rescattering is evaluated using the ANL-Osaka dynamical coupled channel model for the meson production reactions. It is found the final state interaction will affects the ν N cross section extracted in the previous analysis of the ν d data.

Ground Motion Prediction for M7+ scenarios on the San Andreas Fault using the Virtual Earthquake Approach

NASA Astrophysics Data System (ADS)

Denolle, M.; Dunham, E. M.; Prieto, G.; Beroza, G. C.

2013-05-01

There is no clearer example of the increase in hazard due to prolonged and amplified shaking in sedimentary, than the case of Mexico City in the 1985 Michoacan earthquake. It is critically important to identify what other cities might be susceptible to similar basin amplification effects. Physics-based simulations in 3D crustal structure can be used to model and anticipate those effects, but they rely on our knowledge of the complexity of the medium. We propose a parallel approach to validate ground motion simulations using the ambient seismic field. We compute the Earth's impulse response combining the ambient seismic field and coda-wave enforcing causality and symmetry constraints. We correct the surface impulse responses to account for the source depth, mechanism and duration using a 1D approximation of the local surface-wave excitation. We call the new responses virtual earthquakes. We validate the ground motion predicted from the virtual earthquakes against moderate earthquakes in southern California. We then combine temporary seismic stations on the southern San Andreas Fault and extend the point source approximation of the Virtual Earthquake Approach to model finite kinematic ruptures. We confirm the coupling between source directivity and amplification in downtown Los Angeles seen in simulations.

Simple systematization of vibrational excitation cross-section calculations for resonant electron-molecule scattering in the boomerang and impulse models.

PubMed

Sarma, Manabendra; Adhikari, S; Mishra, Manoj K

2007-01-28

Vibrational excitation (nu(f)<--nu(i)) cross-sections sigma(nu(f)<--nu(i) )(E) in resonant e-N(2) and e-H(2) scattering are calculated from transition matrix elements T(nu(f),nu(i) )(E) obtained using Fourier transform of the cross correlation function , where psi(nu(i))(R,t) approximately =e(-iH(A(2))-(R)t/h phi(nu(i))(R) with time evolution under the influence of the resonance anionic Hamiltonian H(A(2) (-))(A(2) (-)=N(2)(-)/H(2) (-)) implemented using Lanczos and fast Fourier transforms. The target (A(2)) vibrational eigenfunctions phi(nu(i))(R) and phi(nu(f))(R) are calculated using Fourier grid Hamiltonian method applied to potential energy (PE) curves of the neutral target. Application of this simple systematization to calculate vibrational structure in e-N(2) and e-H(2) scattering cross-sections provides mechanistic insights into features underlying presence/absence of structure in e-N(2) and e-H(2) scattering cross-sections. The results obtained with approximate PE curves are in reasonable agreement with experimental/calculated cross-section profiles, and cross correlation functions provide a simple demarcation between the boomerang and impulse models.

Predictive factors of excessive online poker playing.

PubMed

Hopley, Anthony A B; Nicki, Richard M

2010-08-01

Despite the widespread rise of online poker playing, there is a paucity of research examining potential predictors for excessive poker playing. The aim of this study was to build on recent research examining motives for Texas Hold'em play in students by determining whether predictors of other kinds of excessive gambling apply to Texas Hold'em. Impulsivity, negative mood states, dissociation, and boredom proneness have been linked to general problem gambling and may play a role in online poker. Participants of this study were self-selected online poker players (N = 179) who completed an online survey. Results revealed that participants played an average of 20 hours of online poker a week and approximately 9% of the sample was classified as a problem gambler according to the Canadian Problem Gambling Index. Problem gambling, in this sample, was uniquely predicted by time played, dissociation, boredom proneness, impulsivity, and negative affective states, namely depression, anxiety, and stress.

Analysis of gas turbine engines using water and oxygen injection to achieve high Mach numbers and high thrust

NASA Technical Reports Server (NTRS)

Henneberry, Hugh M.; Snyder, Christopher A.

1993-01-01

An analysis of gas turbine engines using water and oxygen injection to enhance performance by increasing Mach number capability and by increasing thrust is described. The liquids are injected, either separately or together, into the subsonic diffuser ahead of the engine compressor. A turbojet engine and a mixed-flow turbofan engine (MFTF) are examined, and in pursuit of maximum thrust, both engines are fitted with afterburners. The results indicate that water injection alone can extend the performance envelope of both engine types by one and one-half Mach numbers at which point water-air ratios reach 17 or 18 percent and liquid specific impulse is reduced to some 390 to 470 seconds, a level about equal to the impulse of a high energy rocket engine. The envelope can be further extended, but only with increasing sacrifices in liquid specific impulse. Oxygen-airflow ratios as high as 15 percent were investigated for increasing thrust. Using 15 percent oxygen in combination with water injection at high supersonic Mach numbers resulted in thrust augmentation as high as 76 percent without any significant decrease in liquid specific impulse. The stoichiometric afterburner exit temperature increased with increasing oxygen flow, reaching 4822 deg R in the turbojet engine at a Mach number of 3.5. At the transonic Mach number of 0.95 where no water injection is needed, an oxygen-air ratio of 15 percent increased thrust by some 55 percent in both engines, along with a decrease in liquid specific impulse of 62 percent. Afterburner temperature was approximately 4700 deg R at this high thrust condition. Water and/or oxygen injection are simple and straightforward strategies to improve engine performance and they will add little to engine weight. However, if large Mach number and thrust increases are required, liquid flows become significant, so that operation at these conditions will necessarily be of short duration.

A parameter quantifying radiation damping of bay oscillations excited by incident tsunamis

NASA Astrophysics Data System (ADS)

Endoh, Takahiro; Inazu, Daisuke; Waseda, Takuji; Hibiya, Toshiyuki

2018-04-01

The transient response of a bay with a narrow mouth to incident tsunamis is interpreted as the convolution of the input signal with the impulse response obtained by an inverse Fourier transform of the response curve of the oscillatory system with one degree of freedom. The rate of radiation damping associated with energy escaping seaward through the bay mouth is expressed in terms of the quality factor Q, which determines the decaying envelope of the impulse response. The value of Q of the resonant peak is approximated by the ratio of the resonant frequency ω0 to the bandwidth between frequencies at which the power spectral density of sea level within the bay drops to half of the peak value. Since the shape of the frequency power spectrum during the tsunami event is almost similar to that in the normal state in the neighborhood of ω0, Q can be estimated from sea level datasets in the normal state. Although the amplitude and phase of the impulse response need to be adjusted using the first crest or trough of the observed leading wave, this approach proves to work well in examining the transient responses of Miyako Bay and Kushimoto Bay on the Japanese Pacific coast to incident tsunamis.

Plasma Thruster Development: Magnetoplasmadynamic Propulsion, Status and Basic Problems.

DTIC Science & Technology

1986-02-01

34 9 Sublimation Rates vs. Temperature for Typical Electrode Materials 65 10 Time to Reach Melting vs. Surface Heat Load (One-Dimensional, Large Area...Approx.) for Different Electrode Materials and Initial Temperatures 75 V LIST OF TABLES TABLE PAGE I Models of Thruster Types (with approximation (1...much higher specific impulse values than the minimum must be achieved in order to obtain acceptable effi- Sciencies , e.g. for 30% efficiency with argon

Noise elimination algorithm for modal analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bao, X. X., E-mail: baoxingxian@upc.edu.cn; Li, C. L.; Xiong, C. B.

2015-07-27

Modal analysis is an ongoing interdisciplinary physical issue. Modal parameters estimation is applied to determine the dynamic characteristics of structures under vibration excitation. Modal analysis is more challenging for the measured vibration response signals are contaminated with noise. This study develops a mathematical algorithm of structured low rank approximation combined with the complex exponential method to estimate the modal parameters. Physical experiments using a steel cantilever beam with ten accelerometers mounted, excited by an impulse load, demonstrate that this method can significantly eliminate noise from measured signals and accurately identify the modal frequencies and damping ratios. This study provides amore » fundamental mechanism of noise elimination using structured low rank approximation in physical fields.« less

ESCORT: A Pratt & Whitney nuclear thermal propulsion and power system for manned mars missions

NASA Astrophysics Data System (ADS)

Feller, Gerald J.; Joyner, Russell

1999-01-01

The purpose of this paper is to describe the conceptual design of an upgrade to the Pratt & Whitney ESCORT nuclear thermal rocket engine. The ESCORT is a bimodal engine capable of supporting a wide range of vehicle propulsive and electrical power requirements. The ESCORT engine is powered by a fast-spectrum beryllium-reflected CERMET-fueled nuclear reactor. In propulsive mode, the reactor is used to heat hot hydrogen to approximately 2700 K which is expanded through a converging/diverging nozzle to generate thrust. Heat pickup in the nozzle and the radial beryllium reflectors is used to drive the turbomachinery in the ESCORT expander cycle. In electrical mode, the reactor is used to heat a mixture of helium and xenon to drive a closed-loop Brayton cycle in order to generate electrical energy. This closed loop system has the additional function of a decay heat removal system after the propulsive mode operation is discontinued. The original ESCORT design was capable of delivering 4448.2 N (1000 lbf) of thrust at a vacuum impulse level of approximately 900 s. Design Reference Mission requirements (DRM) from NASA Johnson Space Center and NASA Lewis Research Center studies in 1997 and 1998 have detailed upgraded requirements for potential manned Mars missions. The current NASA DRM requires a nuclear thermal propulsion system capable of delivering total mission requirements of 200170 N (45000 lbf) thrust and 50 kWe of spacecraft electrical power. This is met assuming three engines capable of each delivering 66723 N (15000 lbf) of vacuum thrust and 25 kWe of electrical power. The individual engine requirements were developed assuming three out of three engine reliability for propulsion and two out of three engine reliability for spacecraft electrical power. The approximate target vacuum impulse is 925 s. The Pratt & Whitney ESCORT concept was upgraded to meet these requirements. The hexagonal prismatic fuel elements were modified to address the uprated power requirements while maintaining the peak fuel temperature below the 2880 K limit for W-UO2 CERMET fuels. A system integrated performance methodology was developed to assess the sensitivity to weight, thrust and impulse to the DRM requirements. Propellant tanks, shielding, and Brayton cycle power conversion unit requirements were included in this evaluation.

Response of the solar atmosphere to a simple flare burst: UV emission from the flare transition layer.

NASA Astrophysics Data System (ADS)

Shmeleva, O. P.

The flare transition layer exists as a relatively steady formation even during impulsive heating. It is maintained by a heat flow from the high-temperature plasma, where the major part of the electron beam energy is absorbed. The lifetime of this plasma is much greater than the impulsive heating time. Intensities of resonance UV lines are calculated using both the model of impulsive nonthermal heating by energetic electrons and the model of continuous thermal heating. The calculated line intensity is almost constant during a long time. The line Doppler shifts predicted by the former model match observations. This suggests that the model represents sufficiently well the actual dynamics of the flare plasma. The flare transition layer is a thin formation, its thickness being Δξ = 1021m-2. It is therefore described adequately within the p = const approximation though the picture of hydrodynamic response of the solar atmosphere to the impulsive heating by energy flows is rather complicated and nonsteady, of course. The intensities of the C IV λλ154.8, 155.1 nm and O VI λλ103.2, 103.8 nm lines are calculated within the scope of the model of continuous thermal heating, in which the conductive heating of the flare transition layer is balanced by radiative cooling. The line intensities are proportional to the pressure in the layer, which permits the pressure to be found from the observed line intensities. The analysis reveals that both heating models adequately represent the actual structure and dynamics of plasma in a flare. In the flare transition layer, the classical heat conduction always does work.

Précis of Breakdown of Will.

PubMed

Ainslie, George

2005-10-01

Behavioral science has long been puzzled by the experience of temptation, the resulting impulsiveness, and the variably successful control of this impulsiveness. In conventional theories, a governing faculty like the ego evaluates future choices consistently over time, discounting their value for delay exponentially, that is, by a constant rate; impulses arise when this ego is confronted by a conditioned appetite. Breakdown of Will (Ainslie 2001) presents evidence that contradicts this model. Both people and nonhuman animals spontaneously discount the value of expected events in a curve where value is divided approximately by expected delay, a hyperbolic form that is more bowed than the rational, exponential curve. With hyperbolic discounting, options that pay off quickly will be temporarily preferred to richer but slower-paying alternatives, a phenomenon that, over periods from minutes to days, can account for impulsive behaviors, and over periods of fractional seconds can account for involuntary behaviors. Contradictory reward-getting processes can in effect bargain with each other, and stable preferences can be established by the perception of recurrent choices as test cases (precedents) in recurrent intertemporal prisoner's dilemmas. The resulting motivational pattern resembles traditional descriptions of the will, as well as of compulsive phenomena that can now be seen as side-effects of will: over-concern with precedent, intractable but circumscribed failures of self-control, a motivated ("dynamic") unconscious, and an inability to exploit emotional rewards. Hyperbolic curves also suggest a means of reducing classical conditioning to motivated choice, the last necessary step for modeling many involuntary processes like emotion and appetite as reward-seeking behaviors; such modeling, in turn, provides a rationale for empathic reward and the "construction" of reality.

Unusual Emissions at Various Energies and Coronal Mass Ejection Prior to the November 4, 2003 Large Solar Flare

NASA Astrophysics Data System (ADS)

Kaufmann, Pierre; Holman, G. D.; Su, Y.; Gimenez de Castro, C.; Correia, E.; de Souza, R. V.; Marun, A.; Pereyra, P.

2010-05-01

The November 4, 2003 GOES X28 flare was the largest ever recorded in its class. It produced the first evidence of the two spectrally separated radio/far-infrared emission components, one at microwaves and another in the THz range of frequencies (Kaufmann et al. 2004). We analyzed the 20 minutes before the impulsive onset of this event and found unusual activity at X-rays (RHESSI), at sub-THz frequencies (SST), at H-alpha (BBSO) and at microwaves (Itapetinga 7 GHz polarimeter, RSTN and OVSA). SOHO LASCO images have shown a large CME launched well before the large burst onset. The unusual activity began at about 19 27 UT with a slow rise at 6-10 keV and the start of a precursor at 7 GHz. Pulsations at sub-THz became pronounced, exhibiting correlations with RHESSI 25-50 keV pulsations and similar pulsations at 7 GHz. Impulsive bursts were detected with peaks at 19 34 UT at 100-300 keV and 7 GHz. LASCO movie show a large CME which linear extrapolation to the solar surface correspond to the first H-alpha BBSO brightening, suggesting an approximate launch time at about 1934 UT, close to the hard X-ray and microwave impulsive bursts and nearly 8 minutes before the onset of the large flare. These events had different locations within the AR that included the major flare location at the solar west limb, as indicated by SST pulses positions and images obtained by RHESSI and BBSO. The pulsations phenomena and superimposed impulsive events might represent the complex energy buildup mechanisms leading to the CME launch, quite distinct in time and space from the major flare that exploded afterwards.

PPT Thrust Stand

NASA Technical Reports Server (NTRS)

Haag, Thomas W.

1995-01-01

A torsional-type thrust stand has been designed and built to test Pulsed Plasma Thrusters (PPT's) in both single shot and repetitive operating modes. Using this stand, momentum per pulse was determined strictly as a function of thrust stand deflection, spring constant, and natural frequency. No empirical corrections were required. The accuracy of the method was verified using a swinging impact pendulum. Momentum transfer data between the thrust stand and the pendulum were consistent to within 1%. Following initial calibrations, the stand was used to test a Lincoln Experimental Satellite (LES-8/9) thruster. The LES-8/9 system had a mass of approximately 7.5 kg, with a nominal thrust to weight ratio of 1.3 x 10(exp -5). A total of 34 single shot thruster pulses were individually measured. The average impulse bit per pulse was 266 microN-s, which was slightly less than the value of 300 microN-s published in previous reports on this device. Repetitive pulse measurements were performed similar to ordinary steady-state thrust measurements. The thruster was operated for 30 minutes at a repetition rate of 132 pulses per minute and yielded an average thrust of 573 microN. Using average thrust, the average impulse bit per pulse was estimated to be 260 microN-s, which was in agreement with the single shot data. Zero drift during the repetitive pulse test was found to be approximately 1% of the measured thrust.

Are neutrons precursors of solar flares?

NASA Astrophysics Data System (ADS)

Martirosyan, H.

2001-08-01

The analysis of data of a worldwide network of neutron monitors (NM) shows, that at local noon and during approximately 4 hours after, the NM sometimes register statistically significant excess. Enhancement of count rate is approxi-mately ≈ 1.5÷2%. Depending on the geographical coordinates the time slice is determined, during which the global increase of a registered ux (characteristic time of the order of tens of hours) is observed. These data are correlated with data from space-borne sensors, proving significant increase ( ≈ 5 ÷ 10 times) of the low energy protons and electrons in near-earth space. In both cases the ux enhancement during tenths of hours is proceeding by an impulse phase of the next solar are. The analysis of data allows to put forward a hypothesis that the enhancement of the protons and electrons ux is stipulated by decay of solar neutrons with energies 10 ÷ 30 MeV . These neutrons during tenths of hours before an impulse phase of a are are born in active areas of the Sun, as a product of thermonuclear reactions (D + d → He3 + n, T + d → He4 + n). The part of neutrons are decaying in the interplanetary space, and part of high en-ergy neutrons (En > 20 V ) penetrate through terrestrial atmosphere (with probability ≈ 10-7 and are registered by neutron monitors.

The effects of a uniform axial magnetic field on the global stability of the rotating-disk boundary-layer

NASA Astrophysics Data System (ADS)

Davies, Christopher; Thomas, Christian

2006-11-01

Following on from the earlier discovery by Lingwood (1995) that the rotating-disk boundary-layer is absolutely unstable, Jasmine & Gajjar (2005) have shown that the application of a uniform axial magnetic field can raise the critical Reynolds number for the onset of absolute instability. As with Lingwood's analysis, a parallel-flow' type of approximation is needed in order to derive this locally-based stability result. The approximation amounts to a freezing out' of the underlying radial variation of the mean flow. Numerical simulations have been conducted to investigate the behaviour of linearized disturbances in the genuine rotating disk boundary layer, where the radial dependence of the mean flow is fully accounted for. This extends the work of Davies & Carpenter (2003), who studied the more usual rotating-disk problem, in the absence of any magnetic field. The simulation results suggest that globally unstable behaviour can be promoted when a uniform axial magnetic field is applied. Impulsively excited disturbances were found to display an increasingly rapid growth at the radial position of the impulse, albeit without any selection of a dominant frequency, as would be more usual for an unstable global mode. This is very similar to the behaviour to that was observed in a recent investigation by Davies & Thomas (2005) of the effects of mass transfer, where suction was also found to promote global instability.

Projection-free approximate balanced truncation of large unstable systems

NASA Astrophysics Data System (ADS)

Flinois, Thibault L. B.; Morgans, Aimee S.; Schmid, Peter J.

2015-08-01

In this article, we show that the projection-free, snapshot-based, balanced truncation method can be applied directly to unstable systems. We prove that even for unstable systems, the unmodified balanced proper orthogonal decomposition algorithm theoretically yields a converged transformation that balances the Gramians (including the unstable subspace). We then apply the method to a spatially developing unstable system and show that it results in reduced-order models of similar quality to the ones obtained with existing methods. Due to the unbounded growth of unstable modes, a practical restriction on the final impulse response simulation time appears, which can be adjusted depending on the desired order of the reduced-order model. Recommendations are given to further reduce the cost of the method if the system is large and to improve the performance of the method if it does not yield acceptable results in its unmodified form. Finally, the method is applied to the linearized flow around a cylinder at Re = 100 to show that it actually is able to accurately reproduce impulse responses for more realistic unstable large-scale systems in practice. The well-established approximate balanced truncation numerical framework therefore can be safely applied to unstable systems without any modifications. Additionally, balanced reduced-order models can readily be obtained even for large systems, where the computational cost of existing methods is prohibitive.

Universal Approximation by Using the Correntropy Objective Function.

PubMed

Nayyeri, Mojtaba; Sadoghi Yazdi, Hadi; Maskooki, Alaleh; Rouhani, Modjtaba

2017-10-16

Several objective functions have been proposed in the literature to adjust the input parameters of a node in constructive networks. Furthermore, many researchers have focused on the universal approximation capability of the network based on the existing objective functions. In this brief, we use a correntropy measure based on the sigmoid kernel in the objective function to adjust the input parameters of a newly added node in a cascade network. The proposed network is shown to be capable of approximating any continuous nonlinear mapping with probability one in a compact input sample space. Thus, the convergence is guaranteed. The performance of our method was compared with that of eight different objective functions, as well as with an existing one hidden layer feedforward network on several real regression data sets with and without impulsive noise. The experimental results indicate the benefits of using a correntropy measure in reducing the root mean square error and increasing the robustness to noise.

The Mars Exploration Rover (MER) Transverse Impulse Rocket System (TIRS)

NASA Technical Reports Server (NTRS)

SanMartin, Alejandro Miguel; Bailey, Erik

2005-01-01

In a very short period of time the MER project successfully developed and tested a system, TIRS/DIMES, to improve the probability of success in the presence of large Martian winds. The successful development of TIRS/DIMES played a big role in the landing site selection process by enabling the landing of Spirit on Gusev crater, a site of very high scientific interest but with known high wind conditions. The performance of TIRS by Spirit at Gusev Crater was excellent. The velocity prediction error was small and Big TIRS was fired reducing the impact horizontal velocity from approximately 23 meters per second to approximately 11 meters per second, well within the airbag capabilities. The performance of TIRS by Opportunity at Meridiani was good. The velocity prediction error was rather large (approximately 6 meters per second, a less than 2 sigma value, but TIRS did not fire which was the correct action.

Impulsivity in borderline personality disorder: a matter of disturbed impulse control or a facet of emotional dysregulation?

PubMed

Sebastian, Alexandra; Jacob, Gitta; Lieb, Klaus; Tüscher, Oliver

2013-02-01

Impulsivity is regarded as a clinical, diagnostic and pathophysiological hallmark of borderline personality disorder (BPD). Self-report measures of impulsivity consistently support the notion of higher impulsive traits in BPD patients as compared to healthy control subjects. Laboratory tests of impulsivity, i.e. neuropsychological tests of impulse control render weak and inconsistent results both across different cognitive components of impulse control and within the same cognitive component of impulse control. One important factor worsening impulsive behaviors and impulse control deficits in BPD is comorbid attention-deficit/hyperactivity disorder (ADHD). In addition, emotional dysregulation interacts with impulse control especially for BPD salient emotions. In sum, although basic mechanisms of impulse control seem not to be disturbed in BPD, clinically well observed impulsive behaviors may be explained by comorbid ADHD or may be the consequence of dysregulation of BPD salient emotions.

Genetic and Modeling Approaches Reveal Distinct Components of Impulsive Behavior

PubMed Central

Nautiyal, Katherine M; Wall, Melanie M; Wang, Shuai; Magalong, Valerie M; Ahmari, Susanne E; Balsam, Peter D; Blanco, Carlos; Hen, René

2017-01-01

Impulsivity is an endophenotype found in many psychiatric disorders including substance use disorders, pathological gambling, and attention deficit hyperactivity disorder. Two behavioral features often considered in impulsive behavior are behavioral inhibition (impulsive action) and delayed gratification (impulsive choice). However, the extent to which these behavioral constructs represent distinct facets of behavior with discrete biological bases is unclear. To test the hypothesis that impulsive action and impulsive choice represent statistically independent behavioral constructs in mice, we collected behavioral measures of impulsivity in a single cohort of mice using well-validated operant behavioral paradigms. Mice with manipulation of serotonin 1B receptor (5-HT1BR) expression were included as a model of disordered impulsivity. A factor analysis was used to characterize correlations between the measures of impulsivity and to identify covariates. Using two approaches, we dissociated impulsive action from impulsive choice. First, the absence of 5-HT1BRs caused increased impulsive action, but not impulsive choice. Second, based on an exploratory factor analysis, a two-factor model described the data well, with measures of impulsive action and choice separating into two independent factors. A multiple-indicator multiple-causes analysis showed that 5-HT1BR expression and sex were significant covariates of impulsivity. Males displayed increased impulsivity in both dimensions, whereas 5-HT1BR expression was a predictor of increased impulsive action only. These data support the conclusion that impulsive action and impulsive choice are distinct behavioral phenotypes with dissociable biological influences that can be modeled in mice. Our work may help inform better classification, diagnosis, and treatment of psychiatric disorders, which present with disordered impulsivity. PMID:27976680

Single-trial extraction of cognitive evoked potentials by combination of third-order correlation and wavelet denoising.

PubMed

Zhang, Z; Tian, X

2005-01-01

The application of a recently proposed denoising implementation for obtaining cognitive evoked potentials (CEPs) at the single-trial level is shown. The aim of this investigation is to develop the technique of extracting CEPs by combining both the third-order correlation and the wavelet denoising methods. First, the noisy CEPs was passed through a finite impulse response filter whose impulse response is matched with the shape of the noise-free signal. It was shown that it is possible to estimate the filter impulse response on basis of a select third-order correlation slice (TOCS) of the input noisy CEPs. Second, the output from the third-order correlation filter is decomposed with bi-orthogonal splines at 5 levels. The CEPs is reconstructed by wavelet final approximation a5. We study its performance in simulated data as well as in cognitive evoked potentials of normal rat and Alzheimer's disease (AD) model rat. For the simulated data, the method gives a significantly better reconstruction of the single-trial cognitive evoked potentials responses in comparison with the simulated data. Moreover, with this approach we obtain a significantly better estimation of the amplitudes and latencies of the simulated CEPs. For the real data, the method clearly improves the visualization of single-trial CEPs. This allows the calculation of better averages as well as the study of systematic or unsystematic variations between trials.

Saccadic entropy of head impulses in acute unilateral vestibular loss.

PubMed

Hsieh, Li-Chun; Lin, Hung-Ching; Lee, Guo-She

2017-10-01

To evaluate the complexity of vestibular-ocular reflex (VOR) in patients with acute unilateral vestibular loss (AUVL) via entropy analysis of head impulses. Horizontal head impulse test (HIT) with high-velocity alternating directions was used to evaluate 12 participants with AUVL and 16 healthy volunteers. Wireless electro-oculography and electronic gyrometry were used to acquire eye positional signals and head velocity signals. The eye velocity signals were then obtained through differentiation, band-pass filtering. The approximate entropy of eye velocity to head velocity (R ApEn ) was used to evaluate chaos property. VOR gain, gain asymmetry ratio, and R ApEn asymmetry ratio were also used to compare the groups. For the lesion-side HIT of the patient group, the mean VOR gain was significantly lower and the mean R ApEn was significantly greater compared with both nonlesion-side HIT and healthy controls (p < 0.01, one-way analysis of variance). Both the R ApEn asymmetry ratio and gain asymmetry ratio of the AUVL group were significantly greater compared with those of the control group (p < 0.05, independent sample t test). Entropy and gain analysis of HIT using wireless electro-oculography system could be used to detect the VOR dysfunctions of AUVL and may become effective methods for evaluating vestibular disorders. Copyright © 2017. Published by Elsevier B.V.

Understanding Coronal Heating through Time-Series Analysis and Nanoflare Modeling

NASA Astrophysics Data System (ADS)

Romich, Kristine; Viall, Nicholeen

2018-01-01

Periodic intensity fluctuations in coronal loops, a signature of temperature evolution, have been observed using the Atmospheric Imaging Assembly (AIA) aboard NASA’s Solar Dynamics Observatory (SDO) spacecraft. We examine the proposal that nanoflares, or impulsive bursts of energy release in the solar atmosphere, are responsible for the intensity fluctuations as well as the megakelvin-scale temperatures observed in the corona. Drawing on the work of Cargill (2014) and Bradshaw & Viall (2016), we develop a computer model of the energy released by a sequence of nanoflare events in a single magnetic flux tube. We then use EBTEL (Enthalpy-Based Thermal Evolution of Loops), a hydrodynamic model of plasma response to energy input, to simulate intensity as a function of time across the coronal AIA channels. We test the EBTEL output for periodicities using a spectral code based on Mann and Lees’ (1996) multitaper method and present preliminary results here. Our ultimate goal is to establish whether quasi-continuous or impulsive energy bursts better approximate the original SDO data.

Novel Approach on the Optimisation of Mid-Course Corrections Along Interplanetary Trajectories

NASA Astrophysics Data System (ADS)

Iorfida, Elisabetta; Palmer, Phil; Roberts, Mark

The primer vector theory, firstly proposed by Lawden, defines a set of necessary conditions to characterise whether an impulsive thrust trajectory is optimal with respect to propellant usage, within a two-body problem context. If the conditions are not satisfied, one or more potential intermediate impulses are performed along the transfer arc, in order to lower the overall cost. The method is based on the propagation of the state transition matrix and on the solution of a boundary value problem, which leads to a mathematical and computational complexity.In this paper, a different approach is introduced. It is based on a polar coordinates transformation of the primer vector which allows the decoupling between its in-plane and out-of-plane components. The out-of-plane component is solved analytically while for the in-plane ones a Hamiltonian approximation is made.The novel procedure reduces the mathematical complexity and the computational cost of Lawden's problem and gives also a different perspective about the optimisation of a transfer trajectory.

The linear interplay of intrinsic and extrinsic noises ensures a high accuracy of cell fate selection in budding yeast

PubMed Central

Li, Yongkai; Yi, Ming; Zou, Xiufen

2014-01-01

To gain insights into the mechanisms of cell fate decision in a noisy environment, the effects of intrinsic and extrinsic noises on cell fate are explored at the single cell level. Specifically, we theoretically define the impulse of Cln1/2 as an indication of cell fates. The strong dependence between the impulse of Cln1/2 and cell fates is exhibited. Based on the simulation results, we illustrate that increasing intrinsic fluctuations causes the parallel shift of the separation ratio of Whi5P but that increasing extrinsic fluctuations leads to the mixture of different cell fates. Our quantitative study also suggests that the strengths of intrinsic and extrinsic noises around an approximate linear model can ensure a high accuracy of cell fate selection. Furthermore, this study demonstrates that the selection of cell fates is an entropy-decreasing process. In addition, we reveal that cell fates are significantly correlated with the range of entropy decreases. PMID:25042292

Long life monopropellant hydrazine thruster evaluation for Space Station Freedom application - Test results

NASA Technical Reports Server (NTRS)

Popp, Christopher G.; Cook, Joseph C.; Ragland, Brenda L.; Pate, Leah R.

1992-01-01

In support of propulsion system thruster development activity for Space Station Freedom (SSF), NASA Johnson Space Center (JSC) conducted a hydrazine thruster technology demonstration program. The goal of this program was to identify impulse life capability of state-of-the-art long life hydrazine thrusters nominally rated for 50 pounds thrust at 300 psia supply pressure. The SSF propulsion system requirement for impulse life of this thruster class is 1.5 million pounds-seconds, corresponding to a throughput of approximately 6400 pounds of propellant. Long life thrusters were procured from The Marquardt Company, Hamilton Standard, and Rocket Research Company, Testing at JSC was completed on the thruster designs to quantify life while simulating expected thruster firing duty cycles and durations for SSF. This paper presents a review of the SSF propulsion system hydrazine thruster requirements, summaries of the three long life thruster designs procured by JSC and acceptance test results for each thruster, the JSC thruster life evaluation test program, and the results of the JSC test program.

Establishment and application of the estimation model for pollutant concentrfation in agriculture drain

NASA Astrophysics Data System (ADS)

Li, Qiangkun; Hu, Yawei; Jia, Qian; Song, Changji

2018-02-01

It is the key point of quantitative research on agricultural non-point source pollution load, the estimation of pollutant concentration in agricultural drain. In the guidance of uncertainty theory, the synthesis of fertilization and irrigation is used as an impulse input to the farmland, meanwhile, the pollutant concentration in agricultural drain is looked as the response process corresponding to the impulse input. The migration and transformation of pollutant in soil is expressed by Inverse Gaussian Probability Density Function. The law of pollutants migration and transformation in soil at crop different growth periods is reflected by adjusting parameters of Inverse Gaussian Distribution. Based on above, the estimation model for pollutant concentration in agricultural drain at field scale was constructed. Taking the of Qing Tong Xia Irrigation District in Ningxia as an example, the concentration of nitrate nitrogen and total phosphorus in agricultural drain was simulated by this model. The results show that the simulated results accorded with measured data approximately and Nash-Sutcliffe coefficients were 0.972 and 0.964, respectively.

Low voltage 30cm ion thruster

NASA Technical Reports Server (NTRS)

1972-01-01

The construction of an ion thruster module (including thruster, power conditioning, and control system) capable of operating for 10,000 hours over a five to one range at an effective specific impulse of approximately 2800 seconds is discussed. The several interrelated tasks involved in the construction of the engine are described. Performance tests of the engine and the effects of various modifications are reported. It was demonstrated that thruster performance and stability were not materially affected by reasonable changes from the nominal operating point.

Impulse Loading Resulting fromShallow Buried Explosives in Water-Saturated Sand

DTIC Science & Technology

2007-01-01

speed photographs of the associated soil cratering and ejecting phenomena. The work of Bergeron et al. [6] was subsequently extended by Braid [7] to...place, a series of water hoses is placed in pit bottom to allow the introduction of water into the pit from the bottom. Next, approximately 14.2 m3...blast. Final report for contract no. DAAK70-92-C-0058, US Army Belvoir RDEC, Ft. Belvoir, VA, 1993. 6 Bergeron, D. Hlady, S., and Braid , M. P

Campground marketing - the impulse camper

Treesearch

Wilbur F. LaPage; Dale P. Ragain

1972-01-01

Impulse or unplanned campground visits may account for one-fourth to one-half of all camping activity. The concepts of impulse travel and impulse camping appear to be potentially useful extensions of the broader concept of impulse purchasing, which has become an important influence in retail marketing. Impulse campers may also be impulse buyers; they were found to...

Unified synchronization criteria in an array of coupled neural networks with hybrid impulses.

PubMed

Wang, Nan; Li, Xuechen; Lu, Jianquan; Alsaadi, Fuad E

2018-05-01

This paper investigates the problem of globally exponential synchronization of coupled neural networks with hybrid impulses. Two new concepts on average impulsive interval and average impulsive gain are proposed to deal with the difficulties coming from hybrid impulses. By employing the Lyapunov method combined with some mathematical analysis, some efficient unified criteria are obtained to guarantee the globally exponential synchronization of impulsive networks. Our method and criteria are proved to be effective for impulsively coupled neural networks simultaneously with synchronizing impulses and desynchronizing impulses, and we do not need to discuss these two kinds of impulses separately. Moreover, by using our average impulsive interval method, we can obtain an interesting and valuable result for the case of average impulsive interval T a =∞. For some sparse impulsive sequences with T a =∞, the impulses can happen for infinite number of times, but they do not have essential influence on the synchronization property of networks. Finally, numerical examples including scale-free networks are exploited to illustrate our theoretical results. Copyright © 2018 Elsevier Ltd. All rights reserved.

Impulsive stabilization and impulsive synchronization of discrete-time delayed neural networks.

PubMed

Chen, Wu-Hua; Lu, Xiaomei; Zheng, Wei Xing

2015-04-01

This paper investigates the problems of impulsive stabilization and impulsive synchronization of discrete-time delayed neural networks (DDNNs). Two types of DDNNs with stabilizing impulses are studied. By introducing the time-varying Lyapunov functional to capture the dynamical characteristics of discrete-time impulsive delayed neural networks (DIDNNs) and by using a convex combination technique, new exponential stability criteria are derived in terms of linear matrix inequalities. The stability criteria for DIDNNs are independent of the size of time delay but rely on the lengths of impulsive intervals. With the newly obtained stability results, sufficient conditions on the existence of linear-state feedback impulsive controllers are derived. Moreover, a novel impulsive synchronization scheme for two identical DDNNs is proposed. The novel impulsive synchronization scheme allows synchronizing two identical DDNNs with unknown delays. Simulation results are given to validate the effectiveness of the proposed criteria of impulsive stabilization and impulsive synchronization of DDNNs. Finally, an application of the obtained impulsive synchronization result for two identical chaotic DDNNs to a secure communication scheme is presented.

Parental monitoring may protect impulsive children from overeating.

PubMed

Bennett, C; Blissett, J

2017-10-01

Research has highlighted links between impulsivity and weight in children and adults. Nevertheless, little is known about the nature of this link in very young children or about the underlying mechanism by which impulsivity leads to greater adiposity. The present study aimed to explore relationships between impulsivity, weight and eating behaviour in a sample of 95 2 to 4-year-olds. Parent-child dyads visited the laboratory and consumed a meal after which parents completed measures of child impulsivity, eating behaviour and parental feeding, whilst children completed impulsivity tasks measuring the impulsivity facet delay of gratification (Snack Delay task), motor impulsivity (Line Walking task) and inhibitory control (Tower task). Pearson's correlations showed that girls with greater motor impulsivity were heavier. Additionally, monitoring moderated the relationship between impulsivity and food approach behaviour, indicating that monitoring may protect more impulsive children from displaying problematic eating behaviours. The motor impulsivity facet appears particularly relevant to child weight; parents can modulate the impact of impulsivity on child eating behaviour through their feeding style. © 2016 World Obesity Federation.

Dynamics of propagation of premature impulses in structurally remodeled infarcted myocardium: a computational analysis

PubMed Central

Cabo, Candido

2014-01-01

Initiation of cardiac arrhythmias typically follows one or more premature impulses either occurring spontaneously or applied externally. In this study, we characterize the dynamics of propagation of single (S2) and double premature impulses (S3), and the mechanisms of block of premature impulses at structural heterogeneities caused by remodeling of gap junctional conductance (Gj) in infarcted myocardium. Using a sub-cellular computer model of infarcted tissue, we found that |INa,max|, prematurity (coupling interval with the previous impulse), and conduction velocity (CV) of premature impulses change dynamically as they propagate away from the site of initiation. There are fundamental differences between the dynamics of propagation of S2 and S3 premature impulses: for S2 impulses |INa,max| recovers fast, prematurity decreases and CV increases as propagation proceeds; for S3 impulses low values of |INa,max| persist, prematurity could increase, and CV could decrease as impulses propagate away from the site of initiation. As a consequence it is more likely that S3 impulses block at sites of structural heterogeneities causing source/sink mismatch than S2 impulses block. Whether premature impulses block at Gj heterogeneities or not is also determined by the values of Gj (and the space constant λ) in the regions proximal and distal to the heterogeneity: when λ in the direction of propagation increases >40%, premature impulses could block. The maximum slope of CV restitution curves for S2 impulses is larger than for S3 impulses. In conclusion: (1) The dynamics of propagation of premature impulses make more likely that S3 impulses block at sites of structural heterogeneities than S2 impulses block; (2) Structural heterogeneities causing an increase in λ (or CV) of >40% could result in block of premature impulses; (3) A decrease in the maximum slope of CV restitution curves of propagating premature impulses is indicative of an increased potential for block at structural heterogeneities. PMID:25566085

Dynamics of propagation of premature impulses in structurally remodeled infarcted myocardium: a computational analysis.

PubMed

Cabo, Candido

2014-01-01

Initiation of cardiac arrhythmias typically follows one or more premature impulses either occurring spontaneously or applied externally. In this study, we characterize the dynamics of propagation of single (S2) and double premature impulses (S3), and the mechanisms of block of premature impulses at structural heterogeneities caused by remodeling of gap junctional conductance (Gj) in infarcted myocardium. Using a sub-cellular computer model of infarcted tissue, we found that |INa,max|, prematurity (coupling interval with the previous impulse), and conduction velocity (CV) of premature impulses change dynamically as they propagate away from the site of initiation. There are fundamental differences between the dynamics of propagation of S2 and S3 premature impulses: for S2 impulses |INa,max| recovers fast, prematurity decreases and CV increases as propagation proceeds; for S3 impulses low values of |INa,max| persist, prematurity could increase, and CV could decrease as impulses propagate away from the site of initiation. As a consequence it is more likely that S3 impulses block at sites of structural heterogeneities causing source/sink mismatch than S2 impulses block. Whether premature impulses block at Gj heterogeneities or not is also determined by the values of Gj (and the space constant λ) in the regions proximal and distal to the heterogeneity: when λ in the direction of propagation increases >40%, premature impulses could block. The maximum slope of CV restitution curves for S2 impulses is larger than for S3 impulses. (1) The dynamics of propagation of premature impulses make more likely that S3 impulses block at sites of structural heterogeneities than S2 impulses block; (2) Structural heterogeneities causing an increase in λ (or CV) of >40% could result in block of premature impulses; (3) A decrease in the maximum slope of CV restitution curves of propagating premature impulses is indicative of an increased potential for block at structural heterogeneities.

Trait impulsive choice predicts resistance to extinction and propensity to relapse to cocaine seeking: a bidirectional investigation.

PubMed

Broos, Nienke; Diergaarde, Leontien; Schoffelmeer, Anton Nm; Pattij, Tommy; De Vries, Taco J

2012-05-01

Despite the strong association between impulsivity and addiction in humans, it is still a matter of debate whether impulsive choice predisposes to, or results from, drug dependence. Furthermore, it is unknown whether treating impulsivity can protect against relapse propensity. Therefore, this study explored the bidirectional relationship between impulsive choice and cocaine taking and seeking in rat behavioral models. In experiment 1, to determine whether impulsive choice predisposes to cocaine taking or seeking, rats were selected based on trait impulsivity in a delayed reward task and subsequently compared on various stages of cocaine self-administration (SA). To examine the consequence of cocaine intake on impulsive choice, impulsivity was monitored once a week throughout various stages of cocaine SA. To determine whether treating impulsive choice can protect against relapse propensity, in experiment 2, impulsive choice was manipulated by pharmacological interventions and cocaine-associated contextual cues. Trait impulsive choice as determined in experiment 1 predicted high extinction resistance and enhanced propensity to context-induced relapse in the cocaine SA model, whereas cocaine intake did not alter impulsive choice. Furthermore, acute changes in impulsive choice were not related to rates of context-induced relapse. Taken together, the current data indicate that trait impulsive choice predicts persistent cocaine seeking during extinction and enhanced propensity to relapse, whereas acute manipulations of impulsive choice had no favorable outcomes on relapse measures. These observations suggest that trait impulsivity can be used as a predictive factor for addiction liability, but treating this impulsivity does not necessarily protect against relapse.

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

PubMed

Morales-Vives, Fabia; Vigil-Colet, Andreu

2012-03-01

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. 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 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. 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.

Questionnaire and behavioral task measures of impulsivity are differentially associated with body mass index: A comprehensive meta-analysis.

PubMed

Emery, Rebecca L; Levine, Michele D

2017-08-01

Although impulsivity has been implicated in the development and maintenance of obesity, evidence linking impulsivity to obesity has been mixed. These mixed findings may be related to differences in the type of impulsivity measures used and the varied domains of impulsivity assessed by each measure. The present meta-analysis aimed to examine the impact of measurement selection on the relationship between impulsivity and body mass index (BMI). A total of 142 articles met inclusion criteria and were comprised of 315,818 participants. Effect sizes consisted of Fisher's z-transformed correlation coefficients, which were weighted by the inverse variance to establish the grand mean estimate of the relationship between impulsivity and BMI. Overall weighted mean effect sizes also were computed for each type and domain of impulsivity measure. Moderator analyses were conducted using a mixed-effects approach to determine if the relationship between impulsivity and BMI varied between the types of impulsivity measures used. On average, participants were 32.25 (SD = 12.41) years of age, with a BMI of 26.63 (SD = 5.73) kg/m2. The overall relationship between impulsivity and BMI was small but significant (r = .07). Behavioral task measures of impulsivity produced significantly larger effect sizes (r = .10) than did questionnaire measures of impulsivity (r = .05). Domains of impulsivity that assessed disinhibited behaviors (r = .10), attentional deficits (r = .11), impulsive decision-making (r = .10), and cognitive inflexibility (r = .17) produced significant effect sizes. These meta-analytic findings demonstrate that impulsivity is positively associated with BMI and further document that this association varies by the type of impulsivity measure used and the domain of impulsivity assessed. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Narcissism predicts impulsive buying: phenotypic and genetic evidence

PubMed Central

Cai, Huajian; Shi, Yuanyuan; Fang, Xiang; Luo, Yu L. L.

2015-01-01

Impulsive buying makes billions of dollars for retail businesses every year, particularly in an era of thriving e-commerce. Narcissism, characterized by impulsivity and materialism, may serve as a potential antecedent to impulsive buying. To test this hypothesis, two studies examined the relationship between narcissism and impulsive buying. In Study 1, we surveyed an online sample and found that while adaptive narcissism was not correlated with impulsive buying, maladaptive narcissism was significantly predictive of the impulsive buying tendency. By investigating 304 twin pairs, Study 2 showed that global narcissism and its two components, adaptive and maladaptive narcissism, as well as the impulsive buying tendency were heritable. The study found, moreover, that the connections between global narcissism and impulsive buying, and between maladaptive narcissism and impulsive buying were genetically based. These findings not only establish a link between narcissism and impulsive buying but also help to identify the origins of the link. The present studies deepen our understanding of narcissism, impulsive buying, and their interrelationship. PMID:26217251

Narcissism predicts impulsive buying: phenotypic and genetic evidence.

PubMed

Cai, Huajian; Shi, Yuanyuan; Fang, Xiang; Luo, Yu L L

2015-01-01

Impulsive buying makes billions of dollars for retail businesses every year, particularly in an era of thriving e-commerce. Narcissism, characterized by impulsivity and materialism, may serve as a potential antecedent to impulsive buying. To test this hypothesis, two studies examined the relationship between narcissism and impulsive buying. In Study 1, we surveyed an online sample and found that while adaptive narcissism was not correlated with impulsive buying, maladaptive narcissism was significantly predictive of the impulsive buying tendency. By investigating 304 twin pairs, Study 2 showed that global narcissism and its two components, adaptive and maladaptive narcissism, as well as the impulsive buying tendency were heritable. The study found, moreover, that the connections between global narcissism and impulsive buying, and between maladaptive narcissism and impulsive buying were genetically based. These findings not only establish a link between narcissism and impulsive buying but also help to identify the origins of the link. The present studies deepen our understanding of narcissism, impulsive buying, and their interrelationship.

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

PubMed

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

2012-06-01

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.

"Impulsive" suicide attempts: What do we really mean?

PubMed

May, Alexis M; Klonsky, E David

2016-07-01

Suicide attempts are often regarded as impulsive acts. However, there is little consensus regarding the definition or clinical characteristics of an "impulsive" attempt. To clarify this issue, we examined 3 indicators of the impulsivity of an attempt: (a) preparation, (b) time contemplating the attempt, and (c) self-report that impulsivity motivated the attempt. We examined relationships among the indicators and their relationship to trait impulsivity and characteristics of the suicide attempt. Adult participants (N = 205) with a history of suicide attempts were administered validated interviews and questionnaires. In general, the 3 attempt impulsivity indicators correlated only moderately with each other and not at all with trait impulsivity or with important characteristics of the attempt (e.g., lethality, preattempt communication, motivations). However, there were 2 exceptions. First, intent to die was inversely related to the 3 attempt impulsivity indicators (rs ranged from -.17 to .45) such that more impulsive attempts were associated with lower intent. Second, self-report that the attempt was motivated by impulsivity was related to 3 facets of trait impulsivity (rs ranged from .16 to .41). These findings suggest that individuals endorsing trait impulsivity are likely to describe their attempts as motivated by impulsivity, regardless of the presence of preparation or prolonged contemplation. Overall, study results suggest that the common conception of a unidimensional impulsive attempt may be inaccurate and that the emphasis on general impulsivity in prevention guidelines should be tempered. Implications for suicide risk assessment and prevention are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Trait impulsivity is associated with the risk of falls in Parkinson's disease.

PubMed

Smulders, Katrijn; Esselink, Rianne A; Cools, Roshan; Bloem, Bastiaan R

2014-01-01

Impulsivity is a "tendency to act prematurely without foresight." Clinical experience suggests that such impulsive behavior can impact on the fall risk in Parkinson's disease (PD), but this has never been tested. We investigated whether trait impulsivity is related to fall risk in a large cohort of PD patients. We also investigated whether trait impulsivity affects the fall risk differently for patients with more or less postural instability and gait disability (PIGD). 388 patients with PD (H&Y ≤ 3) completed the Barratt Impulsiveness Scale (BIS-11, higher scores indicating greater impulsivity) to assess trait impulsivity, including three subscales: motor impulsivity (e.g. "I do things without thinking"), attentional impulsivity (e.g. "I concentrate easily") and non-planning (e.g. "I plan tasks carefully"). Falls were registered prospectively for 6 months. Patients classified as non-fallers (0 falls, n = 237) were compared to recurrent PD fallers (>1 fall, n = 78). Total impulsivity scores were higher for recurrent fallers (59.5) compared to non-fallers (56.8; p = .012). This effect was predominantly driven by higher scores on the subscale for attentional impulsivity (p = .003). The difference in attentional impulsivity was independent of gender, disease severity, dopaminergic medication, and cognitive function. Motor and non-planning impulsivity did not differ between recurrent fallers and non-fallers. There was no evidence that impulsivity modulated the association between PIGD and fall risk. This is the first evidence that impulsivity, in particular in the attentional domain, is related to fall risk in PD.

Sweet taste liking is associated with impulsive behaviors in humans

PubMed Central

Weafer, Jessica; Burkhardt, Anne; de Wit, Harriet

2014-01-01

Evidence from both human and animal studies suggests that sensitivity to rewarding stimuli is positively associated with impulsive behaviors, including both impulsive decision making and inhibitory control. The current study examined associations between the hedonic value of a sweet taste and two forms of impulsivity (impulsive choice and impulsive action) in healthy young adults (N = 100). Participants completed a sweet taste test in which they rated their liking of various sweetness concentrations. Subjects also completed measures of impulsive choice (delay discounting), and impulsive action (go/no-go task). Subjects who discounted more steeply (i.e., greater impulsive choice) liked the high sweetness concentration solutions more. By contrast, sweet liking was not related to impulsive action. These findings indicate that impulsive choice may be associated with heightened sensitivity to the hedonic value of a rewarding stimulus, and that these constructs might share common underlying neurobiological mechanisms. PMID:24987343

[Electromagnetic radiation of non-thermal intensity and short exposition as a sub-threshold irritant for the central nervous system].

PubMed

Luk'ianova, S N

2013-01-01

This work represents generalization and the analysis of the long-term own materials characterizing reaction of the brain on electromagnetic radiation of low intensity (energy flow density in the continuous regime or in the impulse approximately 500 microW/sm2) and a short exposition (approximately 30 min). A set of the experimental results received on separate neurons, formations and brain as a whole give an idea about the reaction of the central nervous system to the studied influence. Comparison of these data with the corresponding responses to the known incentives (light, sound, electric current) testifies to the electromagnetic radiation of low energy flow density and a short exposition as a sub-threshold irritant for the central nervous system.

Spin-flip isovector giant resonances from the 90Zr(n,p)90Y reaction at 198 MeV

NASA Astrophysics Data System (ADS)

Raywood, K. J.; Spicer, B. M.; Yen, S.; Long, S. A.; Moinester, M. A.; Abegg, R.; Alford, W. P.; Celler, A.; Drake, T. E.; Frekers, D.; Green, P. E.; Häusser, O.; Helmer, R. L.; Henderson, R. S.; Hicks, K. H.; Jackson, K. P.; Jeppesen, R. G.; King, J. D.; King, N. S.; Miller, C. A.; Officer, V. C.; Schubank, R.; Shute, G. G.; Vetterli, M.; Watson, J.; Yavin, A. I.

1990-06-01

Doubly differential cross sections of the reaction 90Zr(n,p)90Y have been measured at 198 MeV for excitations up to 38 MeV in the residual nucleus. An overall resolution of 1.3 MeV was achieved. The spectra show qualitative agreement in shape and magnitude with recent random phase approximation calculations; however, all of the calculations underestimate the high excitation region of the spectra. A multipole decomposition of the data has been performed using differential cross sections calculated in the distorted-wave impulse approximation. An estimate of the Gamow-Teller strength in the reaction is given. The isovector spin-flip dipole giant resonance has been identified and there is also an indication of isovector monopole strength.

Coupled-Sturmian and perturbative treatments of electron transfer and ionization in high-energy p-He+ collisions

NASA Astrophysics Data System (ADS)

Winter, Thomas G.; Alston, Steven G.

1992-02-01

Cross sections have been determined for electron transfer and ionization in collisions between protons and He+ ions at proton energies from several hundred kilo-electron-volts to 2 MeV. A coupled-Sturmian approach is taken, extending the work of Winter [Phys. Rev. A 35, 3799 (1987)] and Stodden et al. [Phys. Rev. A 41, 1281 (1990)] to high energies where perturbative approaches are expected to be valid. An explicit connection is made with the first-order Born approximation for ionization and the impulse version of the distorted, strong-potential Born approximation for electron transfer. The capture cross section is shown to be affected by the presence of target basis functions of positive energy near v2/2, corresponding to the Thomas mechanism.

Experimental investigation of combustor effects on rocket thrust chamber performance

NASA Technical Reports Server (NTRS)

1972-01-01

A design and experimental program to develop special instrumentation systems, design engine hardware, and conduct tests using LOX/GH2 propellants in which the propellant flow stratification was controlled is described. The mixture ratio was varied from 4.6 to 6 overall. The mixture ratios in the core and outer zone were varied from 3.5 to 6 and 5 to 8, respectively. The range in boundary layer coolant was from 0 to 10 percent of the fuel. The nominal chamber pressure and thrust were 225 psia and 7000 pounds, respectively. Pressure and heat flux profiles as well as gas sampling of the exhaust products were obtained. Specific impulse efficiencies of approximately 94 percent and characteristic velocity efficiencies of approximately 97 percent were obtained during the experiments.

The interactive effect of hunger and impulsivity on food intake and purchase in a virtual supermarket.

PubMed

Nederkoorn, C; Guerrieri, R; Havermans, R C; Roefs, A; Jansen, A

2009-08-01

It has been shown repeatedly that impulsivity, obesity and food intake are related; obese people are more impulsive than lean people and impulsive people eat more than less impulsive people. The relation between impulsivity and food intake might be state dependent; hunger motivates food seeking behaviour and food consumption, especially of high caloric food. Difficulties to overrule automatic behavioural tendencies might make impulsive people more susceptible to the effects of hunger on food selection. Therefore, they are expected to increase their intake more than low impulsive people when feeling hungry. STUDY 1: Fifty-seven female participants were randomly assigned to a hunger or sated condition. Response inhibition (a measure of impulsivity) and food intake were measured. Results show that impulsive participants ate significantly more, but only when feeling hungry. STUDY 2: Ninety-four undergraduate students participated. Hunger, response inhibition and the purchase of food in a virtual supermarket were measured. The same interaction was found: impulsive participants bought most calories, especially from snack food, but only when feeling hungry. Hunger and impulsivity interact in their influence on consumption. These data suggest that reducing hunger during calorie restricting diets is important for successful weight loss, particularly for the impulsive dieters.

The effect of binocular eye position and head rotation plane on the human torsional vestibuloocular reflex.

PubMed

Migliaccio, Americo A; Della Santina, Charles C; Carey, John P; Minor, Lloyd B; Zee, David S

2006-08-01

We examined how the gain of the torsional vestibulo-ocular reflex (VOR) (defined as the instantaneous eye velocity divided by inverted head velocity) in normal humans is affected by eye position, target distance, and the plane of head rotation. In six normal subjects we measured three-dimensional (3D) eye and head rotation axes using scleral search coils, and 6D head position using a magnetic angular and linear position measurement device, during low-amplitude (approximately 20 degrees ), high-velocity (approximately 200 degrees/s), high-acceleration (approximately 4000 degrees /s2) rapid head rotations or 'impulses.' Head impulses were imposed manually and delivered in five planes: yaw (horizontal canal plane), pitch, roll, left anterior-right posterior canal plane (LARP), and right anterior-left posterior canal plane (RALP). Subjects were instructed to fix on one of six targets at eye level. Targets were either straight-ahead, 20 degrees left or 20 degrees right from midline, at distance 15 or 124 cm from the subject. Two subjects also looked at more eccentric targets, 30 degrees left or 30 degrees right from midline. We found that the vertical and horizontal VOR gains increased with the proximity of the target to the subject. Previous studies suggest that the torsional VOR gain should decrease with target proximity. We found, however, that the torsional VOR gain did not change for all planes of head rotation and for both target distances. We also found a dynamic misalignment of the vertical positions of the eyes during the torsional VOR, which was greatest during near viewing with symmetric convergence. This dynamic vertical skew during the torsional VOR arises, in part, because when the eyes are converged, the optical axes are not parallel to the naso-occipital axes around which the eyes are rotating. In five of six subjects, the average skew ranged 0.9 degrees -2.9 degrees and was reduced to <0.4 degrees by a 'torsional' quick-phase (around the naso-occipital axis) occurring <110 ms after the onset of the impulse. We propose that the torsional quick-phase mechanism during the torsional VOR could serve at least three functions: (1) resetting the retinal meridians closer to their usual orientation in the head, (2) correcting for the 'skew' deviation created by misalignment between the axes around which the eyes are rotating and the line of sight, and (3) taking the eyes back toward Listing's plane.

Diet-induced impulsivity: Effects of a high-fat and a high-sugar diet on impulsive choice in rats

PubMed Central

Pirkle, Jesseca R. A.; Kirkpatrick, Kimberly

2017-01-01

Impulsive choice is a common charactertistic among individuals with gambling problems, obesity, and substance abuse issues. Impulsive choice has been classified as a trans-disease process, and understanding the etiology of trait impulsivity could help to understand how diseases and disorders related to impulsive choice are manifested. The Western diet is a possible catalyst of impulsive choice as individuals who are obese and who eat diets high in fat and sugar are typically more impulsive. However, such correlational evidence is unable to discern the direction and causal nature of the relationship. The present study sought to determine how diet may directly contribute to impulsive choice. After 8 weeks of dietary exposure (high-fat, high-sugar, chow), the rats were tested on an impulsive choice task, which presented choices between a smaller-sooner reward (SS) and a larger-later reward (LL). Then, the rats were transferred to a chow diet and retested on the impulsive choice task. The high-sugar and high-fat groups made significantly more impulsive choices than the chow group. Both groups became more self-controlled when they were off the diet, but there were some residual effects of the diet on choice behavior. These results suggest that diet, specifically one high in processed fat or sugar, induces impulsive choice. This diet-induced impulsivity could be a precursor to other disorders that are characterized by impulsivity, such as diet-induced obesity, and could offer potential understanding of the trans-disease nature of impulsive choice. PMID:28662133

Diet-induced impulsivity: Effects of a high-fat and a high-sugar diet on impulsive choice in rats.

PubMed

Steele, Catherine C; Pirkle, Jesseca R A; Kirkpatrick, Kimberly

2017-01-01

Impulsive choice is a common charactertistic among individuals with gambling problems, obesity, and substance abuse issues. Impulsive choice has been classified as a trans-disease process, and understanding the etiology of trait impulsivity could help to understand how diseases and disorders related to impulsive choice are manifested. The Western diet is a possible catalyst of impulsive choice as individuals who are obese and who eat diets high in fat and sugar are typically more impulsive. However, such correlational evidence is unable to discern the direction and causal nature of the relationship. The present study sought to determine how diet may directly contribute to impulsive choice. After 8 weeks of dietary exposure (high-fat, high-sugar, chow), the rats were tested on an impulsive choice task, which presented choices between a smaller-sooner reward (SS) and a larger-later reward (LL). Then, the rats were transferred to a chow diet and retested on the impulsive choice task. The high-sugar and high-fat groups made significantly more impulsive choices than the chow group. Both groups became more self-controlled when they were off the diet, but there were some residual effects of the diet on choice behavior. These results suggest that diet, specifically one high in processed fat or sugar, induces impulsive choice. This diet-induced impulsivity could be a precursor to other disorders that are characterized by impulsivity, such as diet-induced obesity, and could offer potential understanding of the trans-disease nature of impulsive choice.

[Impulse control in addiction: a translational perspective].

PubMed

Schmaal, L; Broos, N; Joos, L; Pattij, T; Goudriaan, A E

2013-01-01

Impulsivity is a hallmark of addiction and predicts treatment response and relapse. Impulsivity is, however, a complex construct. Translational cross-species research is needed to give us greater insight into the neurobiology and the role of impulsivity in addiction and to help with the development of new treatment strategies for improving patients' impulse control. To review recent evidence concerning the concept of impulsivity and the role of impulsivity in addiction. The concept and neurobiology of impulsivity are reviewed from a translational perspective. The role of impulsivity in addiction and implications for treatment are discussed. Our recent translational cross-species study indicates that impulsivity is made up of several, separate independent features with partly distinct underlying neurobiological substrates. There are also indications that these features make a unique and independent contribution to separate stages of the addiction cycle. In addition, the improvement of impulse control is a promising new target area for treatments that could lead to better results. However, those involved in developing new treatment strategies will have to take into account the complexity and multidimensional character of impulsivity.

Stormtime transport of ring current and radiation belt ions

NASA Technical Reports Server (NTRS)

Chen, Margaret W.; Schulz, Michael; Lyons, L. R.; Gorney, David J.

1993-01-01

This is an investigation of stormtime particle transport that leads to formation of the ring current. Our method is to trace the guiding-center motion of representative ions (having selected first adiabatic invariants mu) in response to model substorm-associated impulses in the convection electric field. We compare our simulation results qualitatively with existing analytically tractable idealizations of particle transport (direct convective access and radial diffusion) in order to assess the limits of validity of these approximations. For mu approximately less than 10 MeV/G (E approximately less than 10 keV at L equivalent to 3) the ion drift period on the final (ring-current) drift shell of interest (L equivalent to 3) exceeds the duration of the main phase of our model storm, and we find that the transport of ions to this drift shell is appropriately idealized as direct convective access, typically from open drift paths. Ion transport to a final closed drift path from an open (plasma-sheet) drift trajectory is possible for those portions of that drift path that lie outside the mean stormtime separatrix between closed and open drift trajectories, For mu approximately 10-25 MeV/G (110 keV approximately less than E approximately less than 280 keV at L equivalent to 3) the drift period at L equivalent to 3 is comparable to the postulated 3-hr duration of the storm, and the mode of transport is transitional between direct convective access and transport that resembles radial diffusion. (This particle population is transitional between the ring current and radiation belt). For mu approximately greater than 25 MeV/G (radiation-belt ions having E approximately greater than 280 keV at L equivalent to 3) the ion drift period is considerably shorter than the main phase of a typical storm, and ions gain access to the ring-current region essentially via radial diffusion. By computing the mean and mean-square cumulative changes in 1/L among (in this case) 12 representative ions equally spaced in drift time around the steady-state drift shell of interest (L equivalent to 3), we have estimated (from both our forward and our time-reversed simulations) the time-integrated radial-diffusion coefficients D(sup sim)(sub LL) for particles having selected values of mu approximately greater than 15 MeV/G. The results agree surprisingly well with the predictions (D(sup ql)(sub LL)) of quasilinear radial diffusion theory, despite the rather brief duration (approximately 3 hrs) of our model storm and despite the extreme variability (with frequency) of the spectral-density function that characterizes the applied electric field during our model storm. As expected, the values of D(sup sim)(sub LL) deduced (respectively) from our forward and time-reversed simulations agree even better with each other and with D(sup sim)(sub LL) when the impulse amplitudes which characterize the individual substorms of our model storm are systematically reduced.

Acquisition and deconvolution of seismic signals by different methods to perform direct ground-force measurements

NASA Astrophysics Data System (ADS)

Poletto, Flavio; Schleifer, Andrea; Zgauc, Franco; Meneghini, Fabio; Petronio, Lorenzo

2016-12-01

We present the results of a novel borehole-seismic experiment in which we used different types of onshore-transient-impulsive and non-impulsive-surface sources together with direct ground-force recordings. The ground-force signals were obtained by baseplate load cells located beneath the sources, and by buried soil-stress sensors installed in the very shallow-subsurface together with accelerometers. The aim was to characterize the source's emission by its complex impedance, function of the near-field vibrations and soil stress components, and above all to obtain appropriate deconvolution operators to remove the signature of the sources in the far-field seismic signals. The data analysis shows the differences in the reference measurements utilized to deconvolve the source signature. As downgoing waves, we process the signals of vertical seismic profiles (VSP) recorded in the far-field approximation by an array of permanent geophones cemented at shallow-medium depth outside the casing of an instrumented well. We obtain a significant improvement in the waveform of the radiated seismic-vibrator signals deconvolved by ground force, similar to that of the seismograms generated by the impulsive sources, and demonstrates that the results obtained by different sources present low values in their repeatability norm. The comparison evidences the potentiality of the direct ground-force measurement approach to effectively remove the far-field source signature in VSP onshore data, and to increase the performance of permanent acquisition installations for time-lapse application purposes.

Fermi Detection of Gamma-Ray Emission from the M2 Soft X-Ray Flare on 2010 June 12

NASA Technical Reports Server (NTRS)

Ackermann, M.; Ajello, M.; Allafort, A.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bhat, P. N.;

Cannabinoid CB1 Receptor Activation Mediates the Opposing Effects of Amphetamine on Impulsive Action and Impulsive Choice

PubMed Central

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

2011-01-01

It is well known that acute challenges with psychostimulants such as amphetamine affect impulsive behavior. We here studied the pharmacology underlying the effects of amphetamine in two rat models of impulsivity, the 5-choice serial reaction time task (5-CSRTT) and the delayed reward task (DRT), providing measures of inhibitory control, an aspect of impulsive action, and impulsive choice, respectively. We focused on the role of cannabinoid CB1 receptor activation in amphetamine-induced impulsivity as there is evidence that acute challenges with psychostimulants activate the endogenous cannabinoid system, and CB1 receptor activity modulates impulsivity in both rodents and humans. Results showed that pretreatment with either the CB1 receptor antagonist/inverse agonist SR141716A or the neutral CB1 receptor antagonist O-2050 dose-dependently improved baseline inhibitory control in the 5-CSRTT. Moreover, both compounds similarly attenuated amphetamine-induced inhibitory control deficits, suggesting that CB1 receptor activation by endogenously released cannabinoids mediates this aspect of impulsive action. Direct CB1 receptor activation by Δ9-Tetrahydrocannabinol (Δ9-THC) did, however, not affect inhibitory control. Although neither SR141716A nor O-2050 affected baseline impulsive choice in the DRT, both ligands completely prevented amphetamine-induced reductions in impulsive decision making, indicating that CB1 receptor activity may decrease this form of impulsivity. Indeed, acute Δ9-THC was found to reduce impulsive choice in a CB1 receptor-dependent way. Together, these results indicate an important, though complex role for cannabinoid CB1 receptor activity in the regulation of impulsive action and impulsive choice as well as the opposite effects amphetamine has on both forms of impulsive behavior. PMID:22016780

A path model of different forms of impulsivity with externalizing and internalizing psychopathology: Towards greater specificity.

PubMed

Johnson, Sheri L; Tharp, Jordan A; Peckham, Andrew D; Carver, Charles S; Haase, Claudia M

2017-09-01

A growing empirical literature indicates that emotion-related impulsivity (compared to impulsivity that is unrelated to emotion) is particularly relevant for understanding a broad range of psychopathologies. Recent work, however, has differentiated two forms of emotion-related impulsivity: A factor termed Pervasive Influence of Feelings captures tendencies for emotions (mostly negative emotions) to quickly shape thoughts, and a factor termed Feelings Trigger Action captures tendencies for positive and negative emotions to quickly and reflexively shape behaviour and speech. This study used path modelling to consider links from emotion-related and non-emotion-related impulsivity to a broad range of psychopathologies. Undergraduates completed self-report measures of impulsivity, depression, anxiety, aggression, and substance use symptoms. A path model (N = 261) indicated specificity of these forms of impulsivity. Pervasive Influence of Feelings was related to anxiety and depression, whereas Feelings Trigger Action and non-emotion-related impulsivity were related to aggression and substance use. The findings of this study suggest that emotion-relevant impulsivity could be a potentially important treatment target for a set of psychopathologies. Recent work has differentiated two forms of emotion-related impulsivity. This study tests a multivariate path model linking emotion-related and non-emotion-related impulsivity with multiple forms of psychopathology. Impulsive thoughts in response to negative emotions were related to anxiety and depression. Impulsive actions in response to emotions were related to aggression and substance use, as did non-emotion-related impulsivity. The study was limited by the reliance on self-report measures of impulsivity and psychopathology. There is a need for longitudinal work on how these forms of impulsivity predict the onset and course of psychopathology. © 2017 The British Psychological Society.

Exponential stability preservation in semi-discretisations of BAM networks with nonlinear impulses

NASA Astrophysics Data System (ADS)

Mohamad, Sannay; Gopalsamy, K.

2009-01-01

This paper demonstrates the reliability of a discrete-time analogue in preserving the exponential convergence of a bidirectional associative memory (BAM) network that is subject to nonlinear impulses. The analogue derived from a semi-discretisation technique with the value of the time-step fixed is treated as a discrete-time dynamical system while its exponential convergence towards an equilibrium state is studied. Thereby, a family of sufficiency conditions governing the network parameters and the impulse magnitude and frequency is obtained for the convergence. As special cases, one can obtain from our results, those corresponding to the non-impulsive discrete-time BAM networks and also those corresponding to continuous-time (impulsive and non-impulsive) systems. A relation between the Lyapunov exponent of the non-impulsive system and that of the impulsive system involving the size of the impulses and the inter-impulse intervals is obtained.

Screening method based on walking plantar impulse for detecting musculoskeletal senescence and injury.

PubMed

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

2013-01-01

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

Destabilizing Effects of Impulse in Delayed Bam Neural Networks

NASA Astrophysics Data System (ADS)

Li, Chuandong; Li, Chaojie; Liu, Chao

This paper further studies the global exponential stability of the equilibrium point of the delayed bidirectional associative memory (DBAM) neural networks with impulse effects. Several results characterizing the aggregated effects of impulse and dynamical property of the impulse-free DBAM on the exponential stability of the considered DBAM have been established. It is shown that the impulsive DBAM will preserve the global exponential stability of the impulse-free DBAM even if the impulses have enlarging effects on the states of neurons.

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

PubMed Central

Powers, Robyn L; Russo, Manuela; Mahon, Katie; Brand, Jesse; Braga, Raphael J; Malhotra, Anil K; Burdick, Katherine E

2013-01-01

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 highlight 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. Discussion 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. PMID:24028391

Differences between Impulsive and Non-Impulsive Suicide Attempts among Individuals Treated in Emergency Rooms of South Korea

PubMed Central

Lim, Meerae; Lee, Soojung

2016-01-01

Objective A considerable proportion of suicide attempts are the result of sudden desires. Understanding such impulsive suicide attempts is necessary for effective interventions. We evaluated the impulsivity of suicide attempters treated in emergency rooms. The aim of the study was to identify the characteristics of impulsive suicide attempts by comparing these individuals to those who attempted to commit suicide in a non-impulsive manner. Methods This study analyzed suicide attempters who visited the emergency departments of seven selected university hospitals. A total of 269 medical records in which impulsivity of suicide attempt were confirmed were subject to be analyzed. The impulsivity of the suicide attempt was examined using a summative score of items 6 and 15 on the Suicide Intent Scale. Results A total of 48.0% of the participants were impelled by sudden inclinations to attempt suicide. Impulsive attempters were younger, unmarried and less physical illness than non-impulsive attempters, whereas no significant differences were found on psychiatric history and previous suicide history. Impulsive suicide attempters had suicide ideations that were not as severe (χ2=55.33, p<0.001) or intense (t=-8.38, p<0.001) as their counterparts'. Furthermore, medical results of impulsive suicide attempts were better than non-impulsive suicide attempts (t=-3.77, p<0.001). Conclusion The results suggested that a considerable proportion of suicide attempts were the result of sudden inclinations. Impulsive attempts were made in relatively earlier stages of suicide ideation; consequently, they have less intent than non-impulsive attempts. PMID:27482239

Braking and Propulsive Impulses Increase with Speed during Accelerated and Decelerated Walking

PubMed Central

Peterson, Carrie L.; Kautz, Steven A.; Neptune, Richard R.

2011-01-01

The ability to accelerate and decelerate is important for daily activities and likely more demanding than maintaining a steady-state walking speed. Walking speed is modulated by anterior-posterior (AP) ground reaction force (GRF) impulses. The purpose of this study was to investigate AP impulses across a wide range of speeds during accelerated and decelerated walking. Kinematic and GRF data were collected from ten healthy subjects walking on an instrumented treadmill. Subjects completed trials at steady-state speeds and at four rates of acceleration and deceleration across a speed range of 0 to 1.8 m/s. Mixed regression models were generated to predict AP impulses, step length and frequency from speed, and joint moment impulses from AP impulses during non-steady-state walking. Braking and propulsive impulses were positively related to speed. The braking impulse had a greater relationship with speed than the propulsive impulse, suggesting that subjects modulate the braking impulse more than the propulsive impulse to change speed. Hip and knee extensor, and ankle plantarflexor moment impulses were positively related to the braking impulse, and knee flexor and ankle plantarflexor moment impulses were positively related to the propulsive impulse. Step length and frequency increased with speed and were near the subjects’ preferred combination at steady-state speeds, at which metabolic cost is minimized in nondisabled walking. Thus, these variables may be modulated to minimize metabolic cost while accelerating and decelerating. The outcomes of this work provide the foundation to investigate motor coordination in pathological subjects in response to the increased task demands of non-steady-state walking. PMID:21356590

Impulsivity across the psychosis spectrum: Correlates of cortical volume, suicidal history, and social and global function.

PubMed

Nanda, Pranav; Tandon, Neeraj; Mathew, Ian T; Padmanabhan, Jaya L; Clementz, Brett A; Pearlson, Godfrey D; Sweeney, John A; Tamminga, Carol A; Keshavan, Matcheri S

2016-01-01

Patients with psychotic disorders appear to exhibit greater impulsivity-related behaviors relative to healthy controls. However, the neural underpinning of this impulsivity remains uncertain. Furthermore, it remains unclear how impulsivity might differ or be conserved between psychotic disorder diagnoses in mechanism and manifestation. In this study, self-reported impulsivity, measured by Barratt Impulsiveness Scale (BIS), was compared between 305 controls (HC), 139 patients with schizophrenia (SZ), 100 with schizoaffective disorder (SZA), and 125 with psychotic bipolar disorder (PBP). In each proband group, impulsivity was associated with regional cortical volumes (using FreeSurfer analysis of T1 MRI scans), suicide attempt history, Global Assessment of Functioning (GAF), and Social Functioning Scale (SFS). BIS scores were found to differ significantly between participant groups, with SZA and PBP exhibiting significantly higher impulsivity than SZ, which exhibited significantly higher impulsivity than HC. BIS scores were significantly related to suicide attempt history, and they were inversely associated with GAF, SFS, and bilateral orbitofrontal cortex (OFC) volume in both SZA and PBP, but not SZ. These findings indicate that psychotic disorders, particularly those with prominent affective symptoms, are characterized by elevated self-reported impulsivity measures. Impulsivity's correlations with suicide attempt history, GAF, and SFS suggest that impulsivity may be a mediator of clinical outcome. The observed impulsivity-OFC correlations corroborate the importance of OFC deficits in impulsivity. These correlations' presence in SZA and PBP but not in SZ suggests that impulsivity may have different underlying mechanisms in affective and non-affective psychotic disorders. Copyright © 2015 Elsevier B.V. All rights reserved.

Impulsive and non-impulsive suicide attempts in patients treated for alcohol dependence.

PubMed

Wojnar, Marcin; Ilgen, Mark A; Czyz, Ewa; Strobbe, Stephen; Klimkiewicz, Anna; Jakubczyk, Andrzej; Glass, Jennifer; Brower, Kirk J

2009-05-01

Suicidal behavior has been recognized as an increasing problem among alcohol-dependent subjects. The aim of the study was to identify correlates of impulsive and non-impulsive suicide attempts among a treated population of alcohol-dependent patients. A total of 154 patients with alcohol dependence consecutively admitted for addiction treatment participated in the study. Suicidal behavior was assessed together with severity of alcohol dependence, childhood abuse, impulsivity, and family history. A stop-signal procedure was used as a behavioral measure of impulsivity. Lifetime suicide attempts were reported by 43% of patients in alcohol treatment; of which 62% were impulsive. Compared to patients without a suicide attempt, those with a non-impulsive attempt were more likely to have a history of sexual abuse (OR=7.17), a family history of suicide (OR=4.09), and higher scores on a personality measure of impulsiveness (OR=2.27). The only significant factor that distinguished patients with impulsive suicide attempts from patients without a suicide attempt and from patients with a non-impulsive suicide attempt was a higher level of behavioral impulsivity (OR=1.84-2.42). Retrospective self-report of suicide attempts and family history. Lack of diagnostic measure.

A statistical study of merging galaxies: Theory and observations

NASA Technical Reports Server (NTRS)

Chatterjee, Tapan K.

1990-01-01

A study of the expected frequency of merging galaxies is conducted, using the impulsive approximation. Results indicate that if we consider mergers involving galaxy pairs without halos in a single crossing time or orbital period, the expected frequency of mergers is two orders of magnitude below the observed value for the present epoch. If we consider mergers involving several orbital periods or crossing times, the expected frequency goes up by an order of magnitude. Preliminary calculation indicate that if we consider galaxy mergers between pairs with massive halos, the merger is very much hastened.

He3 Spin-Dependent Cross Sections and Sum Rules

NASA Astrophysics Data System (ADS)

Slifer, K.; Amarian, M.; Auerbach, L.; Averett, T.; Berthot, J.; Bertin, P.; Bertozzi, B.; Black, T.; Brash, E.; Brown, D.; Burtin, E.; Calarco, J.; Cates, G.; Chai, Z.; Chen, J.-P.; Choi, Seonho; Chudakov, E.; Ciofi Degli Atti, C.; Cisbani, E.; de Jager, C. W.; Deur, A.; Disalvo, R.; Dieterich, S.; Djawotho, P.; Finn, M.; Fissum, K.; Fonvieille, H.; Frullani, S.; Gao, H.; Gao, J.; Garibaldi, F.; Gasparian, A.; Gilad, S.; Gilman, R.; Glamazdin, A.; Glashausser, C.; Glöckle, W.; Golak, J.; Goldberg, E.; Gomez, J.; Gorbenko, V.; Hansen, J.-O.; Hersman, B.; Holmes, R.; Huber, G. M.; Hughes, E.; Humensky, B.; Incerti, S.; Iodice, M.; Jensen, S.; Jiang, X.; Jones, C.; Jones, G.; Jones, M.; Jutier, C.; Kamada, H.; Ketikyan, A.; Kominis, I.; Korsch, W.; Kramer, K.; Kumar, K.; Kumbartzki, G.; Kuss, M.; Lakuriqi, E.; Laveissiere, G.; Lerose, J. J.; Liang, M.; Liyanage, N.; Lolos, G.; Malov, S.; Marroncle, J.; McCormick, K.; McKeown, R. D.; Meziani, Z.-E.; Michaels, R.; Mitchell, J.; Nogga, A.; Pace, E.; Papandreou, Z.; Pavlin, T.; Petratos, G. G.; Pripstein, D.; Prout, D.; Ransome, R.; Roblin, Y.; Rowntree, D.; Rvachev, M.; Sabatié, F.; Saha, A.; Salmè, G.; Scopetta, S.; Skibiński, R.; Souder, P.; Saito, T.; Strauch, S.; Suleiman, R.; Takahashi, K.; Teijiro, S.; Todor, L.; Tsubota, H.; Ueno, H.; Urciuoli, G.; van der Meer, R.; Vernin, P.; Voskanian, H.; Witała, H.; Wojtsekhowski, B.; Xiong, F.; Xu, W.; Yang, J.-C.; Zhang, B.; Zolnierczuk, P.

2008-07-01

We present a measurement of the spin-dependent cross sections for the He→3(e→,e')X reaction in the quasielastic and resonance regions at a four-momentum transfer 0.1≤Q2≤0.9GeV2. The spin-structure functions have been extracted and used to evaluate the nuclear Burkhardt-Cottingham and extended Gerasimov-Drell-Hearn sum rules for the first time. The data are also compared to an impulse approximation calculation and an exact three-body Faddeev calculation in the quasielastic region.

Rayleigh wave effects in an elastic half-space.

NASA Technical Reports Server (NTRS)

Aggarwal, H. R.

1972-01-01

Consideration of Rayleigh wave effects in a homogeneous isotropic linearly elastic half-space subject to an impulsive uniform disk pressure loading. An approximate formula is obtained for the Rayleigh wave effects. It is shown that the Rayleigh waves near the center of loading arise from the portion of the dilatational and shear waves moving toward the axis, after they originate at the edge of the load disk. A study is made of the vertical displacement due to Rayleigh waves at points on the axis near the surface of the elastic half-space.

Adiabatic invariants in stellar dynamics. 2: Gravitational shocking

NASA Technical Reports Server (NTRS)

Weinberg, Martin D.

1994-01-01

A new theory of gravitational shocking based on time-dependent perturbation theory shows that the changes in energy and angular momentum due to a slowly varying disturbance are not exponentially small for stellar dynamical systems in general. It predicts significant shock heating by slowly varying perturbations previously thought to be negligible according to the adiabatic criterion. The theory extends the scenarios traditionally computed only with the impulse approximation and is applicable to a wide class of disturbances. The approach is applied specifically to the problem of disk shocking of star clusters.

Research program in nuclear and solid state physics. [including pion absorption spectra and muon spin precession

NASA Technical Reports Server (NTRS)

1974-01-01

The survey of negative pion absorption reactions on light and medium nuclei was continued. Muon spin precession was studied using an iron target. An impulse approximation model of the pion absorption process implied that the ion will absorb almost exclusively on nucleon pairs, single nucleon absorption being suppressed by energy and momentum conservation requirements. For measurements on both paramagnetic and ferromagnetic iron, the external magnetic field was supplied by a large C-type electromagnet carrying a current of about 100 amperes.

Test Area C-72 and Line of Sight, Eglin Air Force Base, Florida Final Range Environmental Assessment (REA), Revision 1

DTIC Science & Technology

2011-07-28

missions. It was recognized that a failure to remove the trees could result in valuable data loss on Eglin test missions. Four different methods have...4-57 to 4-59) The munitions used on TA C-72 would cause noise levels ofless than 115 P- weighted (impulse sound) decibels, and receptors would not...approximate calculation is: 600 x the cube root of the net explosive weight (NEW) = distance to the reservation boundary (infeet) . No detonation can

Healthfulness of Foods Advertised in Small and Nontraditional Urban Stores in Minneapolis–St. Paul, Minnesota, 2014

PubMed Central

Pelletier, Jennifer E.; Erickson, Darin J.; Caspi, Caitlin E.; Harnack, Lisa J.; Laska, Melissa N.

2016-01-01

Introduction Shopping at small food stores, such as corner stores and convenience stores, is linked with unhealthful food and beverage purchases, poor diets, and high risk of obesity. However, information on how foods and beverages are marketed at small stores is limited. The objective of this study was to examine advertisements and product placements for healthful and less healthful foods and beverages at small stores in Minneapolis–St. Paul, Minnesota. Methods We conducted in-store audits of 119 small and nontraditional food retailers (corner/small grocery stores, food–gas marts, pharmacies, and dollar stores) randomly selected from licensing lists in Minneapolis–St. Paul in 2014. We analyzed data on exterior and interior advertisements of foods and beverages and product placement. Results Exterior and interior advertisements for healthful foods and beverages were found in less than half of stores (exterior, 37% [44 of 119]; interior, 20% [24 of 119]). Exterior and interior advertisements for less healthful items were found in approximately half of stores (exterior, 46% [55 of 119]); interior, 66% [78 of 119]). Of the 4 store types, food–gas marts were most likely to have exterior and interior advertisements for both healthful and less healthful items. Corner/small grocery stores and dollar stores had fewer advertisements of any type. Most stores (77%) had at least 1 healthful item featured as an impulse buy (ie, an item easily reached at checkout), whereas 98% featured at least 1 less healthful item as an impulse buy. Conclusion Findings suggest imbalanced advertising and product placement of healthful and less healthful foods and beverages at small food stores in Minneapolis–St. Paul; less healthful items were more apt to be featured as impulse buys. Future interventions and polices should encourage reductions in advertisements and impulse-buy placements of unhealthful products, particularly in food–gas marts, and encourage advertisements of healthful products. PMID:27831683

Healthfulness of Foods Advertised in Small and Nontraditional Urban Stores in Minneapolis-St. Paul, Minnesota, 2014.

PubMed

Barnes, Timothy L; Pelletier, Jennifer E; Erickson, Darin J; Caspi, Caitlin E; Harnack, Lisa J; Laska, Melissa N

2016-11-10

Shopping at small food stores, such as corner stores and convenience stores, is linked with unhealthful food and beverage purchases, poor diets, and high risk of obesity. However, information on how foods and beverages are marketed at small stores is limited. The objective of this study was to examine advertisements and product placements for healthful and less healthful foods and beverages at small stores in Minneapolis-St. Paul, Minnesota. We conducted in-store audits of 119 small and nontraditional food retailers (corner/small grocery stores, food-gas marts, pharmacies, and dollar stores) randomly selected from licensing lists in Minneapolis-St. Paul in 2014. We analyzed data on exterior and interior advertisements of foods and beverages and product placement. Exterior and interior advertisements for healthful foods and beverages were found in less than half of stores (exterior, 37% [44 of 119]; interior, 20% [24 of 119]). Exterior and interior advertisements for less healthful items were found in approximately half of stores (exterior, 46% [55 of 119]); interior, 66% [78 of 119]). Of the 4 store types, food-gas marts were most likely to have exterior and interior advertisements for both healthful and less healthful items. Corner/small grocery stores and dollar stores had fewer advertisements of any type. Most stores (77%) had at least 1 healthful item featured as an impulse buy (ie, an item easily reached at checkout), whereas 98% featured at least 1 less healthful item as an impulse buy. Findings suggest imbalanced advertising and product placement of healthful and less healthful foods and beverages at small food stores in Minneapolis-St. Paul; less healthful items were more apt to be featured as impulse buys. Future interventions and polices should encourage reductions in advertisements and impulse-buy placements of unhealthful products, particularly in food-gas marts, and encourage advertisements of healthful products.

Impulsive And Long Duration High-Energy Gamma-Ray Emission From The Very Bright 2012 March 7 Solar Flares

DOE PAGES

Ajello, M.

2014-06-10

The Fermi Large Area Telescope (LAT) observed two bright X-class solar ares on 2012 March 7, and detected gamma-rays up to 4 GeV. We detected gamma-rays both during the impulsive and temporally-extended emission phases, with emission above 100 MeV lasting for approximately 20 hours. Accurate localization of the gamma-ray production site(s) coincide with the solar active region from which X-ray emissions associated with these ares originated. Our analysis of the > 100 MeV gamma-ray emission shows a relatively rapid monotonic decrease in flux during the first hour of the impulsive phase, and a much slower, almost monotonic decrease in fluxmore » for the next 20 hours. The spectra can be adequately described by a power law with a high energy exponential cutoff, or as resulting from the decay of neutral pions produced by accelerated protons and ions with an isotropic power-law energy distribution. The required proton spectrum has a number index 3, with minor variations during the impulsive phase, while during the temporally extended phase the spectrum softens monotonically, starting with index 4. The > 30 MeV proton flux and spectra observed near the Earth by the GOES satellites also show a monotonic flux decrease and spectral softening during the extended phase, but with a harder spectrum, with index 3. Based on the Fermi-LAT and GOES observations of the flux and spectral evolution of these bright ares, we explore the relative merits of prompt and continuous acceleration scenarios, hadronic and leptonic emission processes, and acceleration at the solar corona by the fast Coronal Mass Ejections (CME) as explanations for the observations. We conclude that the most likely scenario is continuous acceleration of protons in the solar corona which penetrate the lower solar atmosphere and produce pions that decay into gamma-rays.« less

Impulsive And Long Duration High-Energy Gamma-Ray Emission From The Very Bright 2012 March 7 Solar Flares

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ajello, M.

The Fermi Large Area Telescope (LAT) observed two bright X-class solar ares on 2012 March 7, and detected gamma-rays up to 4 GeV. We detected gamma-rays both during the impulsive and temporally-extended emission phases, with emission above 100 MeV lasting for approximately 20 hours. Accurate localization of the gamma-ray production site(s) coincide with the solar active region from which X-ray emissions associated with these ares originated. Our analysis of the > 100 MeV gamma-ray emission shows a relatively rapid monotonic decrease in flux during the first hour of the impulsive phase, and a much slower, almost monotonic decrease in fluxmore » for the next 20 hours. The spectra can be adequately described by a power law with a high energy exponential cutoff, or as resulting from the decay of neutral pions produced by accelerated protons and ions with an isotropic power-law energy distribution. The required proton spectrum has a number index 3, with minor variations during the impulsive phase, while during the temporally extended phase the spectrum softens monotonically, starting with index 4. The > 30 MeV proton flux and spectra observed near the Earth by the GOES satellites also show a monotonic flux decrease and spectral softening during the extended phase, but with a harder spectrum, with index 3. Based on the Fermi-LAT and GOES observations of the flux and spectral evolution of these bright ares, we explore the relative merits of prompt and continuous acceleration scenarios, hadronic and leptonic emission processes, and acceleration at the solar corona by the fast Coronal Mass Ejections (CME) as explanations for the observations. We conclude that the most likely scenario is continuous acceleration of protons in the solar corona which penetrate the lower solar atmosphere and produce pions that decay into gamma-rays.« less

Individual differences in impulsive action and dopamine transporter function in rat orbitofrontal cortex.

PubMed

Yates, J R; Darna, M; Beckmann, J S; Dwoskin, L P; Bardo, M T

2016-01-28

Impulsivity, which can be subdivided into impulsive action and impulsive choice, is implicated as a factor underlying drug abuse vulnerability. Although previous research has shown that dopamine (DA) systems in prefrontal cortex are involved in impulsivity and substance abuse, it is not known if inherent variation in DA transporter (DAT) function contributes to impulsivity. The current study determined if individual differences in either impulsive action or impulsive choice are related to DAT function in orbitofrontal (OFC) and/or medial prefrontal cortex (mPFC). Rats were first tested both for impulsive action in a cued go/no-go task and for impulsive choice in a delay-discounting task. Following behavioral evaluation, in vitro [(3)H]DA uptake assays were performed in OFC and mPFC isolated from individual rats. Vmax in OFC, but not mPFC, was correlated with performance in the cued go/no-go task, with decreased OFC DAT function being associated with high impulsive action. In contrast, Vmax in OFC and mPFC was not correlated with performance in the delay-discounting task. The current results demonstrate that impulsive behavior in cued go/no-go performance is associated with decreased DAT function in OFC, suggesting that hyperdopaminergic tone in this prefrontal subregion mediates, at least in part, increased impulsive action. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

Impulsive choice and pre-exposure to delays: iv. effects of delay- and immediacy-exposure training relative to maturational changes in impulsivity.

PubMed

Renee Renda, C; Rung, Jillian M; Hinnenkamp, Jay E; Lenzini, Stephanie N; Madden, Gregory J

2018-04-23

Impulsive choice describes preference for smaller, sooner rewards over larger, later rewards. Excessive delay discounting (i.e., rapid devaluation of delayed rewards) underlies some impulsive choices, and is observed in many maladaptive behaviors (e.g., substance abuse, gambling). Interventions designed to reduce delay discounting may provide therapeutic gains. One such intervention provides rats with extended training with delayed reinforcers. When compared to a group given extended training with immediate reinforcers, delay-exposed rats make significantly fewer impulsive choices. To what extent is this difference due to delay-exposure training shifting preference toward self-control or immediacy-exposure training (the putative control group) shifting preference toward impulsivity? The current study compared the effects of delay- and immediacy-exposure training to a no-training control group and evaluated within-subject changes in impulsive choice across 51 male Wistar rats. Delay-exposed rats made significantly fewer impulsive choices than immediacy-exposed and control rats. Between-group differences in impulsive choice were not observed in the latter two groups. While delay-exposed rats showed large, significant pre- to posttraining reductions in impulsive choice, immediacy-exposed and control rats showed small reductions in impulsive choice. These results suggest that extended training with delayed reinforcers reduces impulsive choice, and that extended training with immediate reinforcers does not increase impulsive choice. © 2018 Society for the Experimental Analysis of Behavior.

In situ impulse test: an experimental and analytical evaluation of data interpretation procedures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1975-08-01

Special experimental field testing and analytical studies were undertaken at Fort Lawton in Seattle, Washington, to study ''close-in'' wave propagation and evaluate data interpretation procedures for a new in situ impulse test. This test was developed to determine the shear wave velocity and dynamic modulus of soils underlying potential nuclear power plant sites. The test is different from conventional geophysical testing in that the velocity variation with strain is determined for each test. In general, strains between 10/sup -1/ and 10/sup -3/ percent are achieved. The experimental field work consisted of performing special tests in a large test sand fillmore » to obtain detailed ''close-in'' data. Six recording transducers were placed at various points on the energy source, while approximately 37 different transducers were installed within the soil fill, all within 7 feet of the energy source. Velocity measurements were then taken simultaneously under controlled test conditions to study shear wave propagation phenomenology and help evaluate data interpretation procedures. Typical test data are presented along with detailed descriptions of the results.« less

Gaussian step-pressure loading of rigid viscoplastic plates. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Hayduk, R. J.; Durling, B. J.

1978-01-01

The response of a thin, rigid viscoplastic plate subjected to a spatially axisymmetric Gaussian step pressure impulse loading was studied analytically. A Gaussian pressure distribution in excess of the collapse load was applied to the plate, held constant for a length of time, and then suddenly removed. The plate deforms with monotonically increasing deflections until the dynamic energy is completely dissipated in plastic work. The simply supported plate of uniform thickness obeys the von Mises yield criterion and a generalized constitutive equation for rigid viscoplastic materials. For the small deflection bending response of the plate, the governing system of equations is essentially nonlinear. Transverse shear stress is neglected in the yield condition and rotary inertia in the equations of dynamic equilibrium. A proportional loading technique, known to give excellent approximations of the exact solution for the uniform load case, was used to linearize the problem and to obtain the analytical solutions in the form of eigenvalue expansions. The effects of load concentration, of an order of magnitude change in the viscosity of the plate material, and of load duration were examined while holding the total impulse constant.

Long life monopropellant hydrazine thruster evaluation for Space Station Freedom application

NASA Technical Reports Server (NTRS)

Popp, Christopher G.; Henderson, John B.

1991-01-01

In support of propulsion system thruster development activity for Space Station Freedom (SSF), NASA Johnson Space Center (JSC) is conducting a hydrazine thruster technology demonstration program. The goal of this program is to identify impulse life capability of state-of-the-art long life hydrazine thrusters nominally rated for 50 pounds thrust at 300 psia supply pressure. The SSF propulsion system requirement for impulse life of this thruster class is 1.5 million pound-seconds, corresponding to a throughput of approximately 6400 pounds of propellant, with a high performance (234 pound-seconds per propellant pound). Long life thrusters were procured from Hamilton Standard, The Marquardt Company, and Rocket Research Company. Testing has initiated on the thruster designs to identify life while simulating expected thruster firing duty cycles and durations for SSF using monopropellant grade hydrazine. This paper presents a review of the SSF propulsion system and requirements as applicable to hydrazine thrusters, the three long life thruster designs procured by JSC and the resultant acceptance test data for each thruster, and the JSC test plan and facility.

Tidal disruption of open clusters in their parent molecular clouds

NASA Technical Reports Server (NTRS)

Long, Kevin

1989-01-01

A simple model of tidal encounters has been applied to the problem of an open cluster in a clumpy molecular cloud. The parameters of the clumps are taken from the Blitz, Stark, and Long (1988) catalog of clumps in the Rosette molecular cloud. Encounters are modeled as impulsive, rectilinear collisions between Plummer spheres, but the tidal approximation is not invoked. Mass and binding energy changes during an encounter are computed by considering the velocity impulses given to individual stars in a random realization of a Plummer sphere. Mean rates of mass and binding energy loss are then computed by integrating over many encounters. Self-similar evolutionary calculations using these rates indicate that the disruption process is most sensitive to the cluster radius and relatively insensitive to cluster mass. The calculations indicate that clusters which are born in a cloud similar to the Rosette with a cluster radius greater than about 2.5 pc will not survive long enough to leave the cloud. The majority of clusters, however, have smaller radii and will survive the passage through their parent cloud.

Completed suicide in childhood.

PubMed

Dervic, Kanita; Brent, David A; Oquendo, Maria A

2008-06-01

Suicide in children and young adolescents up to 14 years of age has increased in many countries, warranting research and clinical awareness. International reported suicide rates per 100,000 in this young population vary between 3.1 and 0 (mean rate worldwide, approximately 0.6/100.000; male-female ratio, 2:1). Suicide occurs only in vulnerable children; this vulnerability begins with parental mood disorder and impulsive aggression, and family history of suicide. Childhood affective and disruptive disorders and abuse are the most often reported psychiatric risk factors. Suicide becomes increasingly common after puberty, most probably because of pubertal onset of depression and substance abuse, which substantially aggravate suicide risk. Biologic findings are scarce; however, serotonergic dysfunction is assumed. The most common precipitants are school and family problems and may include actual/anticipated transitions in these environments. Suicides in children and young adolescents up to 14 years of age often follow a brief period of stress. Cognitive immaturity/misjudgment, age-related impulsivity, and availability of suicide methods play an important role. Psychologic autopsy studies that focus on suicides in this age group are needed.

Study of non-thermal photon production under different scenarios in solar flares. 1: Scenarios and formulations

NASA Technical Reports Server (NTRS)

Perez-Peraza, J.; Alvarez, M.; Gallegos, A.

1985-01-01

In order to study the overall phenomenology involved in solar flares, it is necessary to understand their individual manifestation before building a corresponding description of the global phenomenon. Here the concern is with the production of X and gamma rays in solar flares. Flares are initiated very often within the closed magnetic field configurations of active centers. According (2) when beta = kinetic energy density/magnetic energy density approximately 0.2, the magnetic trap configuration is destructed within the time scale of the impulsive phase of flares ( 100 s). A first particle acceleration stage occurs during this phase as indicated by impulsive microwave and hard X-rays bursts. In some flare events, when the field strength beta is very high, the broken field lines may close again, such that later, in the course of the flash and main phases more hot plasma of very high conductivity is created, and so, the field and frozen plasma expand outward, as the kinetic pressure inside the closed loops increases. The magnetically trapped particles excite strong Alfven wave turbulence of small transverse scale.

Trajectories for High Specific Impulse High Specific Power Deep Space Exploration

NASA Technical Reports Server (NTRS)

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

2002-01-01

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

Simulation of Trajectories for High Specific Impulse Deep Space Exploration

NASA Technical Reports Server (NTRS)

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

2002-01-01

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

Simulation analysis of impulse characteristics of space debris irradiated by multi-pulse laser

NASA Astrophysics Data System (ADS)

Lin, Zhengguo; Jin, Xing; Chang, Hao; You, Xiangyu

2018-02-01

Cleaning space debris with laser is a hot topic in the field of space security research. Impulse characteristics are the basis of cleaning space debris with laser. In order to study the impulse characteristics of rotating irregular space debris irradiated by multi-pulse laser, the impulse calculation method of rotating space debris irradiated by multi-pulse laser is established based on the area matrix method. The calculation method of impulse and impulsive moment under multi-pulse irradiation is given. The calculation process of total impulse under multi-pulse irradiation is analyzed. With a typical non-planar space debris (cube) as example, the impulse characteristics of space debris irradiated by multi-pulse laser are simulated and analyzed. The effects of initial angular velocity, spot size and pulse frequency on impulse characteristics are investigated.

Trait impulsivity components correlate differently with proactive and reactive control

PubMed Central

Huang, Shihua; Zhu, Zude; Zhang, Wei; Chen, Yu; Zhen, Shuangju

2017-01-01

The relationship between impulsivity and cognitive control is still unknown. We hypothesized that trait impulsivity would differentially correlate with specific cognitive control processes. Trait impulsivity was measured by the Barratt Impulsiveness Scale, which assesses motor, attention, and non-planning impulsiveness components. Cognitive control was measured by a hybrid-designed Stroop task, which distinguishes proactive and reactive control. Thirty-three participants performed the Stroop task while they were scanned by functional magnetic resonance imaging. Proactive and reactive control involved increased activity in the fronto-parietal network, and brain activity was associated with impulsivity scores. Specifically, higher motor impulsiveness was associated with a larger proactive control effect in the inferior parietal lobule and a smaller reactive control effect in the right dorsolateral prefrontal cortex (DLPFC) and anterior cingulate contex. Higher attention impulsivity was associated with a smaller proactive control effect in the right DLPFC. Such a correlation pattern suggests that impulsivity trait components are attributable to different cognitive control subsystems. PMID:28423021

Sex differences in impulsive action and impulsive choice.

PubMed

Weafer, Jessica; de Wit, Harriet

2014-11-01

Here, we review the evidence for sex differences in behavioral measures of impulsivity for both humans and laboratory animals. We focus on two specific components of impulsivity: impulsive action (i.e., difficulty inhibiting a prepotent response) and impulsive choice (i.e., difficulty delaying gratification). Sex differences appear to exist on these measures, but the direction and magnitude of the differences vary. In laboratory animals, impulsive action is typically greater in males than females, whereas impulsive choice is typically greater in females. In humans, women discount more steeply than men, but sex differences on measures of impulsive action depend on tasks and subject samples. We discuss implications of these findings as they relate to drug addiction. We also point out the major gaps in this research to date, including the lack of studies designed specifically to examine sex differences in behavioral impulsivity, and the lack of consideration of menstrual or estrous phase or sex hormone levels in the studies. © 2013.

Sex differences in impulsive action and impulsive choice

PubMed Central

Weafer, Jessica; de Wit, Harriet

2013-01-01

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

Activity in the left auditory cortex is associated with individual impulsivity in time discounting.

PubMed

Han, Ruokang; Takahashi, Taiki; Miyazaki, Akane; Kadoya, Tomoka; Kato, Shinya; Yokosawa, Koichi

2015-01-01

Impulsivity dictates individual decision-making behavior. Therefore, it can reflect consumption behavior and risk of addiction and thus underlies social activities as well. Neuroscience has been applied to explain social activities; however, the brain function controlling impulsivity has remained unclear. It is known that impulsivity is related to individual time perception, i.e., a person who perceives a certain physical time as being longer is impulsive. Here we show that activity of the left auditory cortex is related to individual impulsivity. Individual impulsivity was evaluated by a self-answered questionnaire in twelve healthy right-handed adults, and activities of the auditory cortices of bilateral hemispheres when listening to continuous tones were recorded by magnetoencephalography. Sustained activity of the left auditory cortex was significantly correlated to impulsivity, that is, larger sustained activity indicated stronger impulsivity. The results suggest that the left auditory cortex represent time perception, probably because the area is involved in speech perception, and that it represents impulsivity indirectly.

Trait impulsivity components correlate differently with proactive and reactive control.

PubMed

Huang, Shihua; Zhu, Zude; Zhang, Wei; Chen, Yu; Zhen, Shuangju

2017-01-01

The relationship between impulsivity and cognitive control is still unknown. We hypothesized that trait impulsivity would differentially correlate with specific cognitive control processes. Trait impulsivity was measured by the Barratt Impulsiveness Scale, which assesses motor, attention, and non-planning impulsiveness components. Cognitive control was measured by a hybrid-designed Stroop task, which distinguishes proactive and reactive control. Thirty-three participants performed the Stroop task while they were scanned by functional magnetic resonance imaging. Proactive and reactive control involved increased activity in the fronto-parietal network, and brain activity was associated with impulsivity scores. Specifically, higher motor impulsiveness was associated with a larger proactive control effect in the inferior parietal lobule and a smaller reactive control effect in the right dorsolateral prefrontal cortex (DLPFC) and anterior cingulate contex. Higher attention impulsivity was associated with a smaller proactive control effect in the right DLPFC. Such a correlation pattern suggests that impulsivity trait components are attributable to different cognitive control subsystems.

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

PubMed Central

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

2013-01-01

No consensus has been reached on how musculoskeletal system injuries or aging can be explained by a walking plantar impulse. We standardize the plantar impulse by defining a principal axis of plantar impulse. Based upon this standardized plantar impulse, two indexes are presented: plantar pressure record time series and plantar-impulse distribution along the principal axis of plantar impulse. These indexes are applied to analyze the plantar impulse collected by plantar pressure plates from three sources: Achilles tendon ruptures; elderly people (ages 62–71); and young people (ages 19–23). Our findings reveal that plantar impulse distribution curves for Achilles tendon ruptures change irregularly with subjects’ walking speed changes. When comparing distribution curves of the young, we see a significant difference in the elderly subjects’ phalanges plantar pressure record time series. This verifies our hypothesis that a plantar impulse can function as a means to assess and evaluate musculoskeletal system injuries and aging. PMID:24386288

The annoyance of impulsive helicopter noise

NASA Technical Reports Server (NTRS)

Karamcheti, K.

1981-01-01

A total of 96 impulsive and non-impulsive sounds were rated for annoyance by 10 subjects. The signals had the same amplitude spectrum with a maximum frequency of 4.75 kHz. By changing the phase of the spectral components different levels of impulsivity were obtained. The signals had coefficients of impulsivity of 10,8, 7,9, and -0.2 respectively. Further, signals had intensity levels 89 and 95 dBA, pulse repetition rates 10 and 20 Hz, and half the signals had pink noise added at a level 12 dBA lower than the level of the sound. The significant results were: The four females and six male subjects rated the impulsive sounds respectively 3.7 dB less annoying and 2.6 dB more annoying than the non-impulsive sounds. Overall, impulsivity had no effect. The hish pulse repetition rate increased annoyance by 2.2 dB. Addition of pink noise increased annoyance of the non-impulsive sounds 1.2 dB, but decreased the annoyance of the impulsive sounds 0.5 dB.

Second-to-fourth digit ratio and impulsivity: a comparison between offenders and nonoffenders.

PubMed

Hanoch, Yaniv; Gummerum, Michaela; Rolison, Jonathan

2012-01-01

Personality characteristics, particularly impulsive tendencies, have long been conceived as the primary culprit in delinquent behavior. One crucial question to emerge from this line of work is whether impulsivity has a biological basis. To test this possibility, 44 male offenders and 46 nonoffenders completed the Eysenck Impulsivity Questionnaire, and had their 2D∶4D ratio measured. Offenders exhibited smaller right hand digit ratio measurements compared to non-offenders, but higher impulsivity scores. Both impulsivity and 2D∶4D ratio measurements significantly predicted criminality (offenders vs. nonoffenders). Controlling for education level, the 2D∶4D ratio measurements had remained a significant predictor of criminality, while impulsivity scores no longer predicted criminality significantly. Our data, thus, indicates that impulsivity but not 2D∶4D ratio measurements relate to educational attainment. As offenders varied in their number of previous convictions and the nature of their individual crimes, we also tested for differences in 2D∶4D ratio and impulsivity among offenders. Number of previous convictions did not correlate significantly with the 2D∶4D ratio measurements or impulsivity scores. Our study established a link between a biological marker and impulsivity among offenders (and lack thereof among non-offenders), which emphasise the importance of studying the relationship between biological markers, impulsivity and criminal behavior.

Impulsive and non-impulsive suicide attempts in patients treated for alcohol dependence

PubMed Central

Wojnar, Marcin; Ilgen, Mark A.; Czyz, Ewa; Strobbe, Stephen; Klimkiewicz, Anna; Jakubczyk, Andrzej; Glass, Jennifer; Brower, Kirk J.

2009-01-01

Background Suicidal behavior has been recognized as an increasing problem among alcohol-dependent subjects. The aim of the study was to identify correlates of impulsive and non-impulsive suicide attempts among a treated population of alcohol-dependent patients. Methods A total of 154 patients with alcohol dependence consecutively admitted for addiction treatment participated in the study. Suicidal behavior was assessed together with severity of alcohol dependence, childhood abuse, impulsivity, and family history. A stop-signal procedure was used as a behavioral measure of impulsivity. Results and conclusions Lifetime suicide attempts were reported by 43% of patients in alcohol treatment; of which 62% were impulsive. Compared to patients without a suicide attempt, those with a non-impulsive attempt were more likely to have a history of sexual abuse (OR = 7.17), a family history of suicide (OR = 4.09), and higher scores on a personality measure of impulsiveness (OR = 2.27). The only significant factor that distinguished patients with impulsive suicide attempts from patients without a suicide attempt and from patients with a non-impulsive suicide attempt was a higher level of behavioral impulsivity (OR = 1.84 – 2.42). Limitations Retrospective self-report of suicide attempts and family history. Lack of diagnostic measure. PMID:18835498

Affordable Development and Demonstration of a Small Nuclear Thermal Rocket (NTR) Engine and Stage: How Small Is Big Enough?

NASA Technical Reports Server (NTRS)

Borowski, Stanley K.; Sefcik, Robert J.; Fittje, James E.; McCurdy, David R.; Qualls, Arthur L.; Schnitzler, Bruce G.; Werner, James E.; Weitzberg, Abraham; Joyner, Claude R.

2016-01-01

The Nuclear Thermal Rocket (NTR) derives its energy from fission of uranium-235 atoms contained within fuel elements that comprise the engine's reactor core. It generates high thrust and has a specific impulse potential of approximately 900 specific impulse - a 100 percent increase over today's best chemical rockets. The Nuclear Thermal Propulsion (NTP) project, funded by NASA's Advanced Exploration Systems (AES) program, includes five key task activities: (1) Recapture, demonstration, and validation of heritage graphite composite (GC) fuel (selected as the Lead Fuel option); (2) Engine Conceptual Design; (3) Operating Requirements Definition; (4) Identification of Affordable Options for Ground Testing; and (5) Formulation of an Affordable Development Strategy. During fiscal year (FY) 2014, a preliminary Design Development Test and Evaluation (DDT&E) plan and schedule for NTP development was outlined by the NASA Glenn Research Center (GRC), Department of Energy (DOE) and industry that involved significant system-level demonstration projects that included Ground Technology Demonstration (GTD) tests at the Nevada National Security Site (NNSS), followed by a Flight Technology Demonstration (FTD) mission. To reduce cost for the GTD tests and FTD mission, small NTR engines, in either the 7.5 or 16.5 kilopound-force thrust class, were considered. Both engine options used GC fuel and a common fuel element (FE) design. The small approximately 7.5 kilopound-force criticality-limited engine produces approximately157 thermal megawatts and its core is configured with parallel rows of hexagonal-shaped FEs and tie tubes (TTs) with a FE to TT ratio of approximately 1:1. The larger approximately 16.5 kilopound-force Small Nuclear Rocket Engine (SNRE), developed by Los Alamos National Laboratory (LANL) at the end of the Rover program, produces approximately 367 thermal megawatts and has a FE to TT ratio of approximately 2:1. Although both engines use a common 35-inch (approximately 89-centimeters) -long FE, the SNRE's larger diameter core contains approximately 300 more FEs needed to produce an additional 210 thermal megawatts of power. To reduce the cost of the FTD mission, a simple one-burn lunar flyby mission was considered to reduce the liquid hydrogen (LH2) propellant loading, the stage size and complexity. Use of existing and flight proven liquid rocket and stage hardware (e.g., from the RL10B-2 engine and Delta Cryogenic Second Stage) was also maximized to further aid affordability. This paper examines the pros and cons of using these two small engine options, including their potential to support future human exploration missions to the Moon, near Earth asteroids (NEA), and Mars, and recommends a preferred size. It also provides a preliminary assessment of the key activities, development options, and schedule required to affordably build, ground test and fly a small NTR engine and stage within a 10-year timeframe.

Interactive effects of cumulative stress and impulsivity on alcohol consumption.

PubMed

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

2010-08-01

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

On the Spur of the Moment: Intrinsic Predictors of Impulse Sports Betting.

PubMed

Hing, Nerilee; Li, En; Vitartas, Peter; Russell, Alex M T

2018-06-01

Betting on impulse, without thoughtful consideration, research or informed decision-making, may cause financial and other harms and lead to the development of gambling problems. Impulse betting undermines responsible consumption of gambling because it reflects self-regulatory failure, impaired control, unreflective decision-making and betting more than planned. In this paper we define impulse gambling and report on a study that aimed to understand more about the intrinsic characteristics of sports bettors who have a greater tendency to bet on impulse. Specifically, the study aimed to identify behavioural, psychological and socio-demographic predictors of impulse sports betting. A sample of 1816 Australian sports bettors completed an online survey that measured the proportion of their bets placed on impulse both before and during sporting events, as well as bets that were researched and planned in advance. Impulse betting was common, accounting for nearly one-half of all past-year sports bets by respondents. Over three-quarters of respondents had placed one or more impulse bets in the last year and one in seven respondents had made all of their sports bets on impulse. More impulsive sports bettors were characterised as having higher trait impulsiveness, higher problem gambling severity, more frequent sports betting and a shorter history of sports betting. They favoured betting on in-match contingencies instead of overall match outcomes. While health promotion strategies are needed to discourage impulse betting, research into contextual factors that arouse urges to bet would also provide direction for harm minimisation measures that help consumers to resist impulsive betting decisions.

Frontal dysfunctions of impulse control - a systematic review in borderline personality disorder and attention-deficit/hyperactivity disorder.

PubMed

Sebastian, Alexandra; Jung, Patrick; Krause-Utz, Annegret; Lieb, Klaus; Schmahl, Christian; Tüscher, Oliver

2014-01-01

Disorders such as borderline personality disorder (BPD) or attention-deficit/hyperactivity disorder (ADHD) are characterized by impulsive behaviors. Impulsivity as used in clinical terms is very broadly defined and entails different categories including personality traits as well as different cognitive functions such as emotion regulation or interference resolution and impulse control. Impulse control as an executive function, however, is neither cognitively nor neurobehaviorally a unitary function. Recent findings from behavioral and cognitive neuroscience studies suggest related but dissociable components of impulse control along functional domains like selective attention, response selection, motivational control, and behavioral inhibition. In addition, behavioral and neural dissociations are seen for proactive vs. reactive inhibitory motor control. The prefrontal cortex with its sub-regions is the central structure in executing these impulse control functions. Based on these concepts of impulse control, neurobehavioral findings of studies in BPD and ADHD were reviewed and systematically compared. Overall, patients with BPD exhibited prefrontal dysfunctions across impulse control components rather in orbitofrontal, dorsomedial, and dorsolateral prefrontal regions, whereas patients with ADHD displayed disturbed activity mainly in ventrolateral and medial prefrontal regions. Prefrontal dysfunctions, however, varied depending on the impulse control component and from disorder to disorder. This suggests a dissociation of impulse control related frontal dysfunctions in BPD and ADHD, although only few studies are hitherto available to assess frontal dysfunctions along different impulse control components in direct comparison of these disorders. Yet, these findings might serve as a hypothesis for the future systematic assessment of impulse control components to understand differences and commonalities of prefrontal cortex dysfunction in impulsive disorders.

Is impulsivity a common trait in bipolar and unipolar disorders?

PubMed

Henna, Elaine; Hatch, John P; Nicoletti, Mark; Swann, Alan C; Zunta-Soares, Giovana; Soares, Jair C

2013-03-01

  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.   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.   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.   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. © 2013 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

Using Dual Process Models to Examine Impulsivity Throughout Neural Maturation.

PubMed

Leshem, Rotem

2016-01-01

The multivariate construct of impulsivity is examined through neural systems and connections that comprise the executive functioning system. It is proposed that cognitive and behavioral components of impulsivity can be divided into two distinct groups, mediated by (1) the cognitive control system: deficits in top-down cognitive control processes referred to as action/cognitive impulsivity and (2) the socioemotional system: related to bottom-up affective/motivational processes referred to as affective impulsivity. Examination of impulsivity from a developmental viewpoint can guide future research, potentially enabling the selection of more effective interventions for impulsive individuals, based on the cognitive components requiring improvement.

Impulsive Behavior and Associated Clinical Variables in Parkinson's Disease

PubMed Central

Abosch, Aviva; Gupte, Akshay; Eberly, Lynn E.; Tuite, Paul J.; Nance, Martha; Grant, Jon E.

2011-01-01

Parkinson's disease (PD) is a degenerative brain disorder accompanied by the loss of dopaminergic neurons and the presence of motor and non-motor symptoms. We performed a cross-sectional, questionnaire-based analysis of impulsive behavior in our PD clinic population to assess prevalence and associated characteristics. We found a higher prevalence of impulsive behavior (29.7%) than previously reported, and found multiple, concurrent impulsive behaviors in 26% of subjects reporting impulsive behavior. Our findings contribute to the growing awareness of impulsive behavior in PD, and support the need for longitudinal studies to assess changes in impulsive behaviors in Parkinson's patients. PMID:21300194

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

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

Trait impulsivity in suicide attempters: preliminary study.

PubMed

Doihara, Chiho; Kawanishi, Chiaki; Ohyama, Nene; Yamada, Tomoki; Nakagawa, Makiko; Iwamoto, Yohko; Odawara, Toshinari; Hirayasu, Yoshio

2012-10-01

Suicide attempt is a risk factor for suicide. To investigate trait impulsivity among suicide attempters, 93 attempters admitted to an emergency department and 113 healthy controls were evaluated using the Japanese version of the Barratt Impulsiveness Scale (BIS-11J). Impulsivity was analyzed in relation to clinical data in the attempters. Total BIS-11J, attention impulsiveness, and motor impulsiveness scores were significantly higher in the attempters than in the controls. Both total BIS-11J and non-planning impulsiveness scores were significantly higher in attempters with schizophrenia and other psychotic disorders among the diagnostic groups. Control of impulsivity should be considered as one of the targets for suicide prevention. © 2012 The Authors. Psychiatry and Clinical Neurosciences © 2012 Japanese Society of Psychiatry and Neurology.

Noncoplanar minimum delta V two-impulse and three-impulse orbital transfer from a regressing oblate earth assembly parking ellipse onto a flyby trans-Mars asymptotic velocity vector.

NASA Technical Reports Server (NTRS)

Bean, W. C.

1971-01-01

Comparison of two-impulse and three-impulse orbital transfer, using data from a 63-case numerical study. For each case investigated for which coplanarity of the regressing assembly parking ellipse was attained with the target asymptotic velocity vector, a two-impulse maneuver (or a one-impulse equivalent) was found for which the velocity expenditure was within 1% of a reference absolute minimum lower bound. Therefore, for the coplanar cases, use of a minimum delta-V three-impulse maneuver afforded scant improvement in velocity penalty. However, as the noncoplanarity of the parking ellipse and the target asymptotic velocity vector increased, there was a significant increase in the superiority of minimum delta-V three-impulse maneuvers for slowing the growth of velocity expenditure. It is concluded that a multiple-impulse maneuver should be contemplated if nonnominal launch conditions could occur.

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

PubMed Central

Weiss, Nicole H.; Tull, Matthew T.; Viana, Andres G.; Anestis, Michael D.; Gratz, Kim L.

2012-01-01

Recent investigations have demonstrated that posttraumatic stress disorder (PTSD) is associated with a range of impulsive behaviors (e.g., risky sexual behavior and antisocial behavior). The purpose of the present study was to extend extant research by exploring whether emotion dysregulation explains the association between PTSD and impulsive behaviors. Participants were an ethnically diverse sample of 206 substance use disorder (SUD) patients in residential substance abuse treatment. Results demonstrated an association between PTSD and impulsive behaviors, with SUD patients with PTSD reporting significantly more impulsive behaviors than SUD patients without PTSD (in general and when controlling for relevant covariates). Further, emotion dysregulation was found to fully mediate the relationship between PTSD and impulsive behaviors. Results highlight the relevance of emotion dysregulation to impulsive behaviors and suggest that treatments targeting emotion dysregulation may be useful in reducing impulsive behaviors among SUD patients with PTSD. PMID:22366447

Recent Translational Findings on Impulsivity in Relation to Drug Abuse

PubMed Central

Weafer, Jessica; Mitchell, Suzanne H.

2015-01-01

Impulsive behavior is strongly implicated in drug abuse, as both a cause and a consequence of drug use. To understand how impulsive behaviors lead to and result from drug use, translational evidence from both human and non-human animal studies is needed. Here, we review recent (2009 or later) studies that have investigated two major components of impulsive behavior, inhibitory control and impulsive choice, across preclinical and clinical studies. We concentrate on the stop-signal task as the measure of inhibitory control and delay discounting as the measure of impulsive choice. Consistent with previous reports, recent studies show greater impulsive behavior in drug users compared with non-users. Additionally, new evidence supports the prospective role of impulsive behavior in drug abuse, and has begun to identify the neurobiological mechanisms underlying impulsive behavior. We focus on the commonalities and differences in findings between preclinical and clinical studies, and suggest future directions for translational research. PMID:25678985

Off-Axis and Angular Impulse Measurements on a Lightcraft Engine

NASA Astrophysics Data System (ADS)

Libeau, Michael; Myrabo, Leik

2005-04-01

A laser pulse into a Lightcraft engine applies three linear impulses and three angular impulses to the vehicle that depend on the engine's position and orientation with respect to the laser beam. The magnitudes on this impulsive reaction determine the vehicle's autonomous beam-riding characteristics. The impulsive reaction applied to the laser Lightcraft is examined and a device capable of measuring the reaction is designed and tested. Previous work has examined only the linear impulse acting in the thrust direction but the new apparatus, termed the Angular Impulse Measuring Device (AIMD), experimentally measures the dominant side impulse and dominant pitching angular impulse generated by the engine after a laser-strike. Recent tests of an 11/10 scale Model 200 Lightcraft were conducted using a 10KW Army laser at White Sands Missile Range. The resulting measurements are presented as a function of laser beam position.

Impulsivity, perceived self-regulatory success in dieting, and body mass in children and adolescents: A moderated mediation model.

PubMed

Meule, Adrian; Hofmann, Johannes; Weghuber, Daniel; Blechert, Jens

2016-12-01

Impulsivity has been suggested to contribute to overeating and obesity. However, findings are inconsistent and it appears that only specific facets of impulsivity are related to eating-related variables and to body mass. In the current study, relationships between self-reported impulsivity, perceived self-regulatory success in dieting, and objectively measured body mass were examined in N = 122 children and adolescents. Scores on attentional and motor impulsivity interactively predicted perceived self-regulatory success in dieting, but not body mass: Higher attentional impulsivity was associated with lower perceived self-regulatory success at high levels of motor impulsivity, but not at low levels of motor impulsivity. A moderated mediation model revealed an indirect effect of attentional and motor impulsivity on body mass, which was mediated by perceived self-regulatory success in dieting. Thus, results show that only specific facets of impulsivity are relevant in eating- and weight-regulation and interact with each other in the prediction of these variables. These facets of impulsivity, however, are not directly related to higher body mass, but indirectly via lower success in eating-related self-regulation in children and adolescents. Copyright © 2016 Elsevier Ltd. All rights reserved.

Functional and dysfunctional impulsivity and attempted suicide in rural China: A paired case-control study.

PubMed

Liu, Yang-Yang; Wang, Xin-Ting; Qiu, Hui-Min; Xu, Ai-Qiang; Jia, Cun-Xian

2017-07-01

This study aimed to clarify the relationship between functional and dysfunctional impulsivity and attempted suicide in rural China. Data of this study came from the investigation of 407 suicide attempters and their paired non-suicide attempters matched with the same gender, age (±3 years) and residence area in six counties in rural Shandong, China. Suicide attempters accounted for a lower proportion on high functional impulsivity, but a higher proportion on high dysfunctional impulsivity than non-suicide attempters. Dysfunctional impulsivity in the male denoted a significant risk factor for attempted suicide, even after adjustment for psychiatric disorder and demographic factors. Suicide attempters with high dysfunctional impulsivity had a higher percent of family suicide history than those with low dysfunctional impulsivity. High functional impulsivity was a significant protective factor for attempted suicide in the group aged 35-59 years, but a significant risk factor in the group aged 15-34 years. Suicide attempters with low functional impulsivity had poorer economic status and older age than those with high functional impulsivity. Our findings support the key roles of functional and dysfunctional impulsivity in attempted suicide among rural residents of China. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

The Latent Structure of Impulsivity: Impulsive Choice, Impulsive Action, and Impulsive Personality Traits

PubMed Central

MacKillop, James; Weafer, Jessica; Gray, Joshua; Oshri, Assaf; Palmer, Abraham; de Wit, Harriet

2016-01-01

Rationale Impulsivity has been strongly linked to addictive behaviors, but can be operationalized in a number of ways that vary considerably in overlap, suggesting multidimensionality. Objective This study tested the hypothesis that the latent structure among multiple measures of impulsivity would reflect three broad categories: impulsive choice, reflecting discounting of delayed rewards; impulsive action, reflecting ability to inhibit a prepotent motor response; and impulsive personality traits, reflecting self-reported attributions of self-regulatory capacity. Methods The study used a cross-sectional confirmatory factor analysis of multiple impulsivity assessments. Participants were 1252 young adults (62% female) with low levels of addictive behavior who were assessed in individual laboratory rooms at the University of Chicago and the University of Georgia. The battery comprised a delay discounting task, Monetary Choice Questionnaire, Conners Continuous Performance Test, Go/NoGo Task, Stop Signal Task, Barratt Impulsivity Scale, and the UPPS-P Impulsive Behavior Scale. Results The hypothesized three-factor model provided the best fit to the data, although Sensation Seeking was excluded from the final model. The three latent factors were largely unrelated to each other and were variably associated with substance use. Conclusions These findings support the hypothesis that diverse measures of impulsivity can broadly be organized into three categories that are largely distinct from one another. These findings warrant investigation among individuals with clinical levels of addictive behavior and may be applied to understanding the underlying biological mechanisms of these categories. PMID:27449350

Impulse control disorders are associated with multiple psychiatric symptoms in Parkinson's disease.

PubMed

Jaakkola, Elina; Kaasinen, Valtteri; Siri, Chiara; Martikainen, Kirsti; Cilia, Roberto; Niemelä, Solja; Joutsa, Juho

2014-01-01

Impulse control disorders can have serious adverse consequences to the life of a patient with Parkinson's disease. Although impulse control disorders are common, a possible psychiatric comorbidity has not been fully characterized. The aim of this study was to investigate the psychiatric symptoms exhibited by Parkinson's disease patients with impulse control disorders. The study was conducted as a postal survey to patients in the registry of the Finnish Parkinson Association. A total of 290 Parkinson's disease patients were evaluated for impulse control disorders using the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease. Psychiatric symptoms were systematically screened using the Symptom Checklist 90. We found that 108 of the evaluated patients had one or more impulse control disorders. Patients with impulse control disorders had markedly higher scores for symptoms of psychoticism (Bonferroni corrected p < 0.001), interpersonal sensitivity (p < 0.001), obsessive-compulsive disorder (p < 0.001), and depression (p = 0.01) when compared with patients without impulse control disorders. Impulse control disorders were shown to be independently associated with these symptoms. Patients with multiple impulse control disorders had higher scores for depression and obsessive-compulsive symptoms when compared with patients that exhibited only one impulse control disorder. COUNCLUSIONS: Our results confirm the previous observations that impulse control disorders in Parkinson's disease are linked with multiple psychiatric symptoms, including psychoticism, interpersonal sensitivity, obsessive-compulsive symptoms and depression. Clinicians treating these patients should acknowledge the concomitant psychiatric symptoms.

Performance evaluation of digital phase-locked loops for advanced deep space transponders

NASA Technical Reports Server (NTRS)

Nguyen, T. M.; Hinedi, S. M.; Yeh, H.-G.; Kyriacou, C.

1994-01-01

The performances of the digital phase-locked loops (DPLL's) for the advanced deep-space transponders (ADT's) are investigated. DPLL's considered in this article are derived from the analog phase-locked loop, which is currently employed by the NASA standard deep space transponder, using S-domain to Z-domain mapping techniques. Three mappings are used to develop digital approximations of the standard deep space analog phase-locked loop, namely the bilinear transformation (BT), impulse invariant transformation (IIT), and step invariant transformation (SIT) techniques. The performance in terms of the closed loop phase and magnitude responses, carrier tracking jitter, and response of the loop to the phase offset (the difference between in incoming phase and reference phase) is evaluated for each digital approximation. Theoretical results of the carrier tracking jitter for command-on and command-off cases are then validated by computer simulation. Both theoretical and computer simulation results show that at high sampling frequency, the DPLL's approximated by all three transformations have the same tracking jitter. However, at low sampling frequency, the digital approximation using BT outperforms the others. The minimum sampling frequency for adequate tracking performance is determined for each digital approximation of the analog loop. In addition, computer simulation shows that the DPLL developed by BT provides faster response to the phase offset than IIT and SIT.

Frontal Dysfunctions of Impulse Control – A Systematic Review in Borderline Personality Disorder and Attention-Deficit/Hyperactivity Disorder

PubMed Central

Sebastian, Alexandra; Jung, Patrick; Krause-Utz, Annegret; Lieb, Klaus; Schmahl, Christian; Tüscher, Oliver

2014-01-01

Disorders such as borderline personality disorder (BPD) or attention-deficit/hyperactivity disorder (ADHD) are characterized by impulsive behaviors. Impulsivity as used in clinical terms is very broadly defined and entails different categories including personality traits as well as different cognitive functions such as emotion regulation or interference resolution and impulse control. Impulse control as an executive function, however, is neither cognitively nor neurobehaviorally a unitary function. Recent findings from behavioral and cognitive neuroscience studies suggest related but dissociable components of impulse control along functional domains like selective attention, response selection, motivational control, and behavioral inhibition. In addition, behavioral and neural dissociations are seen for proactive vs. reactive inhibitory motor control. The prefrontal cortex with its sub-regions is the central structure in executing these impulse control functions. Based on these concepts of impulse control, neurobehavioral findings of studies in BPD and ADHD were reviewed and systematically compared. Overall, patients with BPD exhibited prefrontal dysfunctions across impulse control components rather in orbitofrontal, dorsomedial, and dorsolateral prefrontal regions, whereas patients with ADHD displayed disturbed activity mainly in ventrolateral and medial prefrontal regions. Prefrontal dysfunctions, however, varied depending on the impulse control component and from disorder to disorder. This suggests a dissociation of impulse control related frontal dysfunctions in BPD and ADHD, although only few studies are hitherto available to assess frontal dysfunctions along different impulse control components in direct comparison of these disorders. Yet, these findings might serve as a hypothesis for the future systematic assessment of impulse control components to understand differences and commonalities of prefrontal cortex dysfunction in impulsive disorders. PMID:25232313

Interactive Effects of Cumulative Stress and Impulsivity on Alcohol Consumption

PubMed Central

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

2013-01-01

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

Behind impulsive suicide attempts: indications from a community study.

PubMed

Wyder, Marianne; De Leo, Diego

2007-12-01

A considerable proportion of suicide attempts are made on impulse. However, knowledge of characteristics of impulsive attempters is still limited. The present study investigated some of these characteristics and aimed to identify the pattern (if any) of suicidal ideation before an impulsive attempt. Data from a randomized and stratified population of 5130 individuals from Brisbane, Australia, were analysed. Computer-assisted telephone interviews (CATI) were adopted to recruit subjects. Those reporting previous suicidal behaviour were sent a questionnaire by mail. One hundred and twelve subjects reported a suicide attempt. One quarter of these described a pattern consistent with an impulsive attempt. Most impulsive attempters experienced suicidal thoughts before their attempt. They were less likely to believe that their attempt would cause death, and less likely to experience depression. Impulsive attempters did not differ significantly from non-impulsive attempters in regards to age, gender, and motivations for the attempt. Surprisingly, no differences in mean scores of trait impulsivity between impulsive and non-impulsive attempters were found. In addition, the majority of suicide attempters (whether impulsive or not) experienced the suicidal process as fluctuating and not as developing along a continuum. The number of attempters who validly entered the study limited our ability to identify potential confounders. Due to the retrospective nature of the survey, the reliability of the information collected may have been affected by recall biases. In addition, as the surveys were administered by mail, it is possible that some questions may have been misinterpreted. The presence of suicidal feelings prior to an attempt constitutes an opportunity for intervention also in impulsive attempters. However, the identification of impulsiveness requires more research efforts.

Formation of Tidally Induced Bars in Galactic Flybys: Prograde versus Retrograde Encounters

NASA Astrophysics Data System (ADS)

Łokas, Ewa L.

2018-04-01

Bars in disk galaxies can be formed by interactions with other systems, including those of comparable mass. It has long been established that the effect of such interactions on galaxy morphology depends strongly on the orbital configuration, in particular the orientation of the intrinsic spin of the galactic disk with respect to its orbital angular momentum. Prograde encounters modify the morphology strongly, including the formation of tidally induced bars, while retrograde flybys should have little effect on morphology. Recent works on the subject reached conflicting conclusions, one using the impulse approximation and claiming no dependence on this angle in the properties of tidal bars. To resolve the controversy, we performed self-consistent N-body simulations of hyperbolic encounters between two identical Milky Way-like galaxies assuming different velocities and impact parameters, with one of the galaxies on a prograde and the other on a retrograde orbit. The galaxies were initially composed of an exponential stellar disk and an NFW dark halo, and they were stable against bar formation in isolation for 3 Gyr. We find that strong tidally induced bars form only in galaxies on prograde orbits. For smaller impact parameters and lower relative velocities, the bars are stronger and have lower pattern speeds. Stronger bars undergo extended periods of buckling instability that thicken their vertical structure. The encounters also lead to the formation of two-armed spirals with strength inversely proportional to the strength of the bars. We conclude that proper modeling of prograde and retrograde encounters cannot rely on the simplest impulse approximation.

Choice-impulsivity in children and adolescents with attention-deficit/hyperactivity disorder (ADHD): A meta-analytic review.

PubMed

Patros, Connor H G; Alderson, R Matt; Kasper, Lisa J; Tarle, Stephanie J; Lea, Sarah E; Hudec, Kristen L

2016-02-01

Impulsive behavior is a core DSM-5 diagnostic feature of attention-deficit/hyperactivity disorder (ADHD) that is associated with several pejorative outcomes. Impulsivity is multidimensional, consisting of two sub-constructs: rapid-response impulsivity and reward-delay impulsivity (i.e., choice-impulsivity). While previous research has extensively examined the presence and implications of rapid-response impulsivity in children with ADHD, reviews of choice-impulsive behavior have been both sparse and relatively circumscribed. This review used meta-analytic methods to comprehensively examine between-group differences in choice-impulsivity among children and adolescents with and without ADHD. Twenty-eight tasks (from 26 studies), consisting of 4320 total children (ADHD=2360, TD=1,960), provided sufficient information to compute an overall between-group effect size for choice-impulsivity performance. Results revealed a medium-magnitude between-group effect size (g=.47), suggesting that children and adolescents with ADHD exhibited moderately increased impulsive decision-making compared to TD children and adolescents. Further, relative to the TD group, children and adolescents with ADHD exhibited similar patterns of impulsive decision-making across delay discounting and delay of gratification tasks. However, the use of single-informant diagnostic procedures relative to multiple informants yielded larger between-group effects, and a similar pattern was observed across samples that excluded females relative to samples that included females. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

PubMed Central

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

2013-01-01

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

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

PubMed

Hamilton, Kristen R; Ansell, Emily B; Reynolds, Brady; Potenza, Marc N; Sinha, Rajita

2013-01-01

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

The Stomach-Derived Hormone Ghrelin Increases Impulsive Behavior

PubMed Central

Anderberg, Rozita H; Hansson, Caroline; Fenander, Maya; Richard, Jennifer E; Dickson, Suzanne L; Nissbrandt, Hans; Bergquist, Filip; Skibicka, Karolina P

2016-01-01

Impulsivity, defined as impaired decision making, is associated with many psychiatric and behavioral disorders, such as attention-deficit/hyperactivity disorder as well as eating disorders. Recent data indicate that there is a strong positive correlation between food reward behavior and impulsivity, but the mechanisms behind this relationship remain unknown. Here we hypothesize that ghrelin, an orexigenic hormone produced by the stomach and known to increase food reward behavior, also increases impulsivity. In order to assess the impact of ghrelin on impulsivity, rats were trained in three complementary tests of impulsive behavior and choice: differential reinforcement of low rate (DRL), go/no-go, and delay discounting. Ghrelin injection into the lateral ventricle increased impulsive behavior, as indicated by reduced efficiency of performance in the DRL test, and increased lever pressing during the no-go periods of the go/no-go test. Central ghrelin stimulation also increased impulsive choice, as evidenced by the reduced choice for large rewards when delivered with a delay in the delay discounting test. In order to determine whether signaling at the central ghrelin receptors is necessary for maintenance of normal levels of impulsive behavior, DRL performance was assessed following ghrelin receptor blockade with central infusion of a ghrelin receptor antagonist. Central ghrelin receptor blockade reduced impulsive behavior, as reflected by increased efficiency of performance in the DRL task. To further investigate the neurobiological substrate underlying the impulsivity effect of ghrelin, we microinjected ghrelin into the ventral tegmental area, an area harboring dopaminergic cell bodies. Ghrelin receptor stimulation within the VTA was sufficient to increase impulsive behavior. We further evaluated the impact of ghrelin on dopamine-related gene expression and dopamine turnover in brain areas key in impulsive behavior control. This study provides the first demonstration that the stomach-produced hormone ghrelin increases impulsivity and also indicates that ghrelin can change two major components of impulsivity—motor and choice impulsivity. PMID:26424164

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

PubMed Central

Janis, Irene Belle; Nock, Matthew K.

2009-01-01

Common clinical wisdom suggests that people who engage in self-injury are impulsive. However, virtually all prior work in this area has relied on individuals’ self-report of impulsiveness, despite evidence that people are limited in their ability to accurately report on cognitive processes that occur outside awareness. To address this knowledge gap, we used performance-based measures of several dimensions of impulsiveness to assess whether people engaging in non-suicidal self-injury (NSSI) demonstrate greater impulsiveness than non-injurers. In Study 1, we compared adolescent self-injurers (n=64) to age, sex, and race/ethnicity matched, non-injurious controls (n=30) on self-report impulsiveness (Schedule for Affective Disorders and Schizophrenia for School Age Children, Present and Lifetime Version, Kaufman et al., 1997), and on performance-based measures of two dimensions of impulsiveness: behavioral disinhibition (Conners’ Continuous Performance Test, Connors, 1995) and risky decision-making (Iowa Gambling Task, Bechara et al., 1994). In Study 2, we compared adult female self-injurers (n=20) to age and race/ethnicity matched, non-injurious controls (n=20) on self-report impulsiveness (Barratt Impulsiveness Scale-11, Patton et al., 1995), and performance-based measures of behavioral disinhibition, risky decision-making, and two measures of delay discounting (Kirby et al., 1999; Richards et al., 1999). In both studies, self-injurers reported greater impulsiveness; however, performance-based measures of impulsiveness failed to detect any between-group differences. We propose several potential explanations for the discrepancies observed between self-report and performance-based measures of impulsiveness and discuss directions for future research on impulsiveness and self-injury. PMID:19758706

Trait and state impulsivity in males with tendency towards Internet-pornography-use disorder.

PubMed

Antons, Stephanie; Brand, Matthias

2018-04-01

Impulsivity has been identified to be involved in the development and maintenance of specific Internet-use disorders (IUD). It can be differentiated between relatively stable trait impulsivity and state impulsivity which is dependent on environmental and affective factors such as craving. Following the I-PACE (Interaction of Person-Affect-Cognition-Execution) model, both trait and state impulsivity may play an interactive role in IUD. The present study aimed to investigate the relationship between trait and state impulsivity and symptom severity of Internet-pornography-use disorder (IPD) as one form of IUD. Fifty heterosexual males participated in this study. State impulsivity was measured with reaction times in a modified stop-signal task. Each participant conducted two blocks of this task which included neutral and pornographic pictures. Moreover, current subjective craving, trait impulsivity, and symptom severity of IPD were assessed using several questionnaires. Results indicate that trait impulsivity was associated with higher symptom severity of IPD. Especially those males with higher trait impulsivity and state impulsivity in the pornographic condition of the stop-signal task as well as those with high craving reactions showed severe symptoms of IPD. The results indicate that both trait and state impulsivity play a crucial role in the development of IPD. In accordance with dual-process models of addiction, the results may be indicative of an imbalance between the impulsive and reflective systems which might be triggered by pornographic material. This may result in loss of control over the Internet-pornography use albeit experiencing negative consequences. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dysfunctional, but not functional, impulsivity is associated with a history of seriously violent behaviour and reduced orbitofrontal and hippocampal volumes in schizophrenia.

PubMed

Kumari, Veena; Barkataki, Ian; Goswami, Sangeeta; Flora, Satinder; Das, Mrigendra; Taylor, Pamela

2009-07-15

Aggression and violent acts have been linked with impulsive responding. We investigated whether impulsive personality trait, especially suggestive of dysfunctional impulsivity (i.e. fast and inaccurate responding where this is non-optimal), is associated with a history of seriously violent behaviour and specific brain deficits in schizophrenia. Twenty-four male participants with schizophrenia, of whom 10 had a history of serious physical violence, and 14 healthy male participants were assessed on impulsiveness (dysfunctional impulsivity), venturesomeness (functional impulsivity), and empathy. All participants underwent magnetic resonance imaging. The results revealed that participants with schizophrenia and a history of violence showed elevated impulsiveness but had comparable scores on venturesomeness and empathy dimensions. Impulsiveness scores correlated negatively with reduced orbitofrontal grey matter volume in both the patient and healthy control groups, and with hippocampal volume in the patient group. Our findings suggest that dysfunctional, but not functional, impulsivity is elevated in patients with schizophrenia with a propensity for repetitive violence, and this in turn appears to be associated with reduce volumes of both the orbitofrontal cortex grey matter and the hippocampus. Violence risk prediction and management strategies in schizophrenia may benefit from including specific measures of dysfunctional impulsive traits.

Limbic striatal dopamine D2/3 receptor availability is associated with non-planning impulsivity in healthy adults after exclusion of potential dissimulators.

PubMed

Reeves, Suzanne J; Polling, Catherine; Stokes, Paul R A; Lappin, Julia M; Shotbolt, Paul P; Mehta, Mitul A; Howes, Oliver D; Egerton, Alice

2012-04-30

Positron emission tomography (PET) studies have reported an association between reduced striatal dopamine D2/3 receptor availability and higher scores on self-report measures of trait impulsivity in healthy adults. However, impulsivity is a multi-faceted construct, and it is unclear which aspect(s) of impulsivity might be driving these associations. The current study aimed to investigate the relationship between limbic (ventral) striatal D2/3 receptor availability and individual components of impulsivity (attentional, motor and non-planning) using the Barratt Impulsiveness Scale (BIS-11) and [(11)C]raclopride PET in 23 healthy volunteers. A partial correlational analysis showed a significant association between non-planning impulsiveness (lack of forethought or 'futuring') and limbic D2/3 receptor availability, which was only apparent after the exclusion of potential dissimulators (indexed by high scores on impression management). Our findings suggest that non-planning impulsiveness is associated with individual variation in limbic striatal D2/3 receptor availability and that different facets of impulsivity may have specific neurochemical correlates. Future studies that combine D2/3 receptor imaging with behavioral measures of impulsivity are required to further elucidate the precise relationship between individual components of trait impulsivity and brain dopaminergic function. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Spectral analysis of hearing protector impulsive insertion loss.

PubMed

Fackler, Cameron J; Berger, Elliott H; Murphy, William J; Stergar, Michael E

2017-01-01

To characterise the performance of hearing protection devices (HPDs) in impulsive-noise conditions and to compare various protection metrics between impulsive and steady-state noise sources with different characteristics. HPDs were measured per the impulsive test methods of ANSI/ASA S12.42- 2010 . Protectors were measured with impulses generated by both an acoustic shock tube and an AR-15 rifle. The measured data were analysed for impulse peak insertion loss (IPIL) and impulsive spectral insertion loss (ISIL). These impulsive measurements were compared to insertion loss measured with steady-state noise and with real-ear attenuation at threshold (REAT). Tested HPDs included a foam earplug, a level-dependent earplug and an electronic sound-restoration earmuff. IPIL for a given protector varied between measurements with the two impulse noise sources, but ISIL agreed between the two sources. The level-dependent earplug demonstrated level-dependent effects both in IPIL and ISIL. Steady-state insertion loss and REAT measurements tended to provide a conservative estimate of the impulsively-measured attenuation. Measurements of IPIL depend strongly on the source used to measure them, especially for HPDs with less attenuation at low frequencies. ISIL provides an alternative measurement of impulse protection and appears to be a more complete description of an HPD's performance.

Spectral analysis of hearing protector impulsive insertion loss

PubMed Central

Fackler, Cameron J.; Berger, Elliott H.; Murphy, William J.; Stergar, Michael E.

2017-01-01

Objective To characterize the performance of hearing protection devices in impulsive-noise conditions and to compare various protection metrics between impulsive and steady-state noise sources with different characteristics. Design Hearing protectors were measured per the impulsive test methods of ANSI/ASA S12.42-2010. Protectors were measured with impulses generated by both an acoustic shock tube and an AR-15 rifle. The measured data were analyzed for impulse peak insertion loss (IPIL) and impulsive spectral insertion loss (ISIL). These impulsive measurements were compared to insertion loss measured with steady-state noise and with real-ear attenuation at threshold (REAT). Study Sample Tested devices included a foam earplug, a level-dependent earplug, and an electronic sound-restoration earmuff. Results IPIL for a given protector varied between measurements with the two impulse noise sources, but ISIL agreed between the two sources. The level-dependent earplug demonstrated level-dependent effects both in IPIL and ISIL. Steady-state insertion loss and REAT measurements tended to provide a conservative estimate of the impulsively-measured attenuation. Conclusions Measurements of IPIL depend strongly on the source used to measure them, especially for hearing protectors with less attenuation at low frequencies. ISIL provides an alternative measurement of impulse protection and appears to be a more complete description of an HPD’s performance. PMID:27885881

[The relationship of attachment features and multi-impulsive symptoms in eating disorders].

PubMed

Szalai, Tamás Dömötör

2017-07-01

Attachment dysfunctions determine borderline personality disorder, which is a frequent background factor of multi-impulsivity; however, the relationship between attachment and multi-impulsive eating disorders is almost unexplored. To compare attachment features of multi-impulsive and classical eating disorder patients with individuals without eating disorders, and to test attachment as a predictor of multi-impulsivity. A cross-sectional survey (148 females, mean age: 30.9 years) investigated maternal, paternal and adult attachment, depression, anxiety, eating disorder and multi-impulsive symptoms in these groups. Altogether 41.3% of the individuals without eating disorders, 17.6% of classical and 11.8% of multi-impulsive eating disorder patients had secure attachment. Multi-impulsive patients had the most severe eating disorder symptoms (F (2) = 17.733) and the lowest paternal care (F (2) = 3.443). Preoccupied and fearful attachment explained 14.5% of multi-impulsive symptoms; however, with adjustment for depression only latter one remained the predictor of multi-impulsivity (t = 5.166, p<0.01). Multi-impulsives are a distinct subgroup of eating disorder patients from the aspects of both symptoms and attachment. Handling their negative moods may hold therapeutic potentials. Longitudinal studies are required to investigate the therapeutic value of paternal care, attachment preoccupation and fearfulness. Orv Hetil. 2017; 158(27): 1058-1066.

Effects of Acoustic Impulses on the Middle Ear

DTIC Science & Technology

2015-10-01

and civilian law enforcement weapon systems, civilian recreational hunting and shooting, and industrial high-level impulsive noises (impacts and...PERSON USAMRMC a. REPORT Unclassified b. ABSTRACT Unclassified c. THIS PAGE Unclassified 19b. TELEPHONE NUMBER (include area code) Standard Form...impulsive noises (impacts and impulses). Keywords: Noise exposure; hearing loss, noise -induced; impulsive noise ; reflex; conditioned response

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

PubMed

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

2015-06-01

Impulsivity has been linked to bulimic symptomatology in a number of studies; however, few have examined this relationship among Black women. We investigated the correlations between impulsivity and bulimic symptoms, and tested impulsivity as a moderator of the body shame/bulimic symptoms relationship among a sample of female undergraduates (N=276; 97 Blacks, 179 Whites). These participants provided data on body shame, impulsivity, and bulimic symptoms (EDE-Q binge eating frequency, BULIT-R, EDI-Bulimia). Among Blacks, impulsivity was significantly positively associated with all bulimic symptoms measures; among Whites, impulsivity was only positively correlated with binge eating frequency. Furthermore, among Blacks, the combination of high body shame and high impulsivity was associated with the highest levels of bulimic symptoms; these findings were not observed among Whites. This study highlights the importance of impulsivity and body shame in identifying bulimic symptomatology among Black women. Copyright © 2015 Elsevier Ltd. All rights reserved.

Relationship between anhedonia and impulsivity in schizophrenia, major depression and schizoaffective disorder.

PubMed

Amr, Mostafa; Volpe, Fernando Madalena

2013-12-01

Anhedonia and impulsivity are prominent symptoms of many psychiatric disorders and may indicate worse prognosis, notably in schizophrenia and major depression. Despite the convergence of negative outcomes from both dimensions, the relationship between anhedonia and impulsivity in psychiatric disorders has been seldom directly assessed. The objective of the present study is to examine the correlations between anhedonia and impulsivity in three diagnostic groups: major depression, schizophrenia and schizoaffective disorder. 121 outpatients (Mansoura University Hospital, Egypt) with major depressive disorder (N=29), schizophrenia (N=59), and schizoaffective disorder (N=33), were assessed and responded to the Beck Depression Inventory, Barrat's Impulsivity Scale-11, and Chapman's Social and Physical Anhedonia Scales. Physical and social anhedonia scores were negatively correlated to impulsivity scores in major depression patients. Conversely, higher scores in physical and social anhedonia predicted higher impulsivity scores in schizophrenia. No correlations between impulsivity and anhedonia were evidenced among schizoaffectives. The relationship between self-reported physical and social anhedonia and impulsivity is diagnosis-specific. Copyright © 2013 Elsevier B.V. All rights reserved.

Chronotype differences in suicidal behavior and impulsivity among suicide attempters.

PubMed

Selvi, Yavuz; Aydin, Adem; Atli, Abdullah; Boysan, Murat; Selvi, Fatih; Besiroglu, Lutfullah

2011-03-01

Morning- and evening-type individuals differ on a number of psychological and biological variables. There has been increasing interest in the relationship between chronotype and personality traits. The aim of this study was to investigate the relationship between impulsivity and chronotype in suicide attempters. Eighty-nine suicide attempters were included in the study, and systematic information on suicide attempts was recorded. The Morningness-Eveningness Questionnaire was applied to determine chronotype, and attempter impulsivity was measured by the total score of the Barratt Impulsiveness Scale. Significant differences between chronotype and impulsivity scores were found. Evening-type subjects reported significantly higher impulsivity scores than both neither- and morning-types. A significant association between chronotype and type of suicide attempt was detected. The largest proportion of violent suicide attempters were evening-type subjects. Violent suicide attempters also reported significantly higher impulsivity scores than nonviolent attempters. Previous studies have pointed out possible relations between eveningness and impulsivity. Current findings suggest that eveningness may be a risk factor for violent suicide attempts by increasing impulsivity.

Time-fixed rendezvous by impulse factoring with an intermediate timing constraint. [for transfer orbits

NASA Technical Reports Server (NTRS)

Green, R. N.; Kibler, J. F.; Young, G. R.

1974-01-01

A method is presented for factoring a two-impulse orbital transfer into a three- or four-impulse transfer which solves the rendezvous problem and satisfies an intermediate timing constraint. Both the time of rendezvous and the intermediate time of a alinement are formulated as any element of a finite sequence of times. These times are integer multiples of a constant plus an additive constant. The rendezvous condition is an equality constraint, whereas the intermediate alinement is an inequality constraint. The two timing constraints are satisfied by factoring the impulses into collinear parts that vectorially sum to the original impulse and by varying the resultant period differences and the number of revolutions in each orbit. Five different types of solutions arise by considering factoring either or both of the two impulses into two or three parts with a limit for four total impulses. The impulse-factoring technique may be applied to any two-impulse transfer which has distinct orbital periods.

Age and Impulsive Behavior in Drug Addiction: A Review of Past Research and Future Directions

PubMed Central

Argyriou, Evangelia; Um, Miji; Carron, Clair; Cyders, Melissa A.

2018-01-01

Impulsive behavior is implicated in the initiation, maintenance, and relapse of drug-seeking behaviors involved in drug addiction. Research shows that changes in impulsive behavior across the lifespan contribute to drug use and addiction. The goal of this review is to examine existing research on the relationship between impulsive behavior and drug use across the lifespan and to recommend directions for future research. Three domains of impulsive behavior are explored in this review: impulsive behavior-related personality traits, delay discounting, and prepotent response inhibition. First, we present previous research on these three domains of impulsive behavior and drug use across developmental stages. Then, we discuss how changes in impulsive behavior across the lifespan are implicated in the progression of drug use and addiction. Finally, we discuss the relatively limited attention given to middle-to-older adults in the current literature, consider the validity of the measures used to assess impulsive behavior in middle-to-older adulthood, and suggest recommendations for future research. PMID:28778737

A universal time scale for vortex ring formation

NASA Astrophysics Data System (ADS)

Gharib, Morteza; Rambod, Edmond; Shariff, Karim

1998-04-01

The formation of vortex rings generated through impulsively started jets is studied experimentally. Utilizing a piston/cylinder arrangement in a water tank, the velocity and vorticity fields of vortex rings are obtained using digital particle image velocimetry (DPIV) for a wide range of piston stroke to diameter (L/D) ratios. The results indicate that the flow field generated by large L/D consists of a leading vortex ring followed by a trailing jet. The vorticity field of the leading vortex ring formed is disconnected from that of the trailing jet. On the other hand, flow fields generated by small stroke ratios show only a single vortex ring. The transition between these two distinct states is observed to occur at a stroke ratio of approximately 4, which, in this paper, is referred to as the ‘formation number’. In all cases, the maximum circulation that a vortex ring can attain during its formation is reached at this non-dimensional time or formation number. The universality of this number was tested by generating vortex rings with different jet exit diameters and boundaries, as well as with various non-impulsive piston velocities. It is shown that the ‘formation number’ lies in the range of 3.6 4.5 for a broad range of flow conditions. An explanation is provided for the existence of the formation number based on the Kelvin Benjamin variational principle for steady axis-touching vortex rings. It is shown that based on the measured impulse, circulation and energy of the observed vortex rings, the Kelvin Benjamin principle correctly predicts the range of observed formation numbers.

Acute alcohol effects on impulsivity: associations with drinking and driving behavior.

PubMed

McCarthy, Denis M; Niculete, Maria E; Treloar, Hayley R; Morris, David H; Bartholow, Bruce D

2012-12-01

Although drink drivers exhibit higher levels of trait impulsivity, no studies have tested the hypothesis that drink drivers experience increased impulsivity while intoxicated. We tested this hypothesis for two impulsivity constructs: delay discounting and behavioral inhibition. A within-subjects study comparing performance of drink drivers and non-drink drivers on behavioral measures of impulsivity in alcohol and no-beverage sessions. A laboratory setting at the University of Missouri. Twenty-nine young adults who were at least moderate drinkers were recruited from the local community and the University of Missouri. Impulsivity was assessed using the Two Choice Impulsivity Paradigm (TCIP) and the Stop-Signal Task. Participants also completed self-report measures of binge drinking and trait impulsivity. In the no-beverage session, TCIP impulsive choices did not differ between drinking and driving groups (P = 0.93). In the alcohol session, drink drivers made more TCIP impulsive choices on both the ascending (P < 0.01) and descending limb (P < 0.01) of the blood alcohol concentration curve than their peers who did not drink and drive. Drinking and driving groups did not differ on the Stop-Signal Task. Supplementary analyses indicated that effects for the TCIP were not explained by individual differences in trait impulsivity. Individuals who report having three or more drinks before driving show greater impulsivity when under the influence of alcohol than those who do not report heavy drinking before driving. © 2012 The Authors, Addiction © 2012 Society for the Study of Addiction.

Acute alcohol effects on impulsivity: Associations with drinking and driving behavior

PubMed Central

McCarthy, Denis M.; Niculete, Maria E.; Treloar, Hayley R.; Morris, David H.; Bartholow, Bruce D.

2012-01-01

Aims Although drink drivers exhibit higher levels of trait impulsivity, no studies have tested the hypothesis that drink drivers experience increased impulsivity while intoxicated. We tested this hypothesis for two impulsivity constructs: delay discounting and behavioral inhibition. Design A within-subjects study comparing performance of drink drivers and non-drink drivers on behavioral measures of impulsivity in alcohol and no-beverage sessions. Setting A laboratory setting at the University of Missouri. Participants Twenty-nine young adults who were at least moderate drinkers were recruited from the local community and the University of Missouri. Measurements Impulsivity was assessed using the Two Choice Impulsivity Paradigm (TCIP) and the Stop-Signal Task. Participants also completed self-report measures of binge drinking and trait impulsivity. Findings In the no-beverage session, TCIP impulsive choices did not differ between drinking and driving groups (p = .93). In the alcohol session, drink drivers made more TCIP impulsive choices on both the ascending (p < .01) and descending limb (p < .01) of the blood alcohol concentration curve than their peers who did not drink and drive. Drinking and driving groups did not differ on the Stop-Signal Task. Supplementary analyses indicated that effects for the TCIP were not explained by individual differences in trait impulsivity. Conclusions Individuals who report having three or more drinks before driving show greater impulsivity when under the influence of alcohol than those who do not report heavy drinking before driving. PMID:22690907

Barratt Impulsivity and Neural Regulation of Physiological Arousal

PubMed Central

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

2015-01-01

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

Mood instability and impulsivity as trait predictors of suicidal thoughts.

PubMed

Peters, Evyn M; Balbuena, Lloyd; Marwaha, Steven; Baetz, Marilyn; Bowen, Rudy

2016-12-01

Impulsivity, the tendency to act quickly without adequate planning or concern for consequences, is a commonly cited risk factor for suicidal thoughts and behaviour. There are many definitions of impulsivity and how it relates to suicidality is not well understood. Mood instability, which describes frequent fluctuations of mood over time, is a concept related to impulsivity that may help explain this relationship. The purpose of this study was to determine whether impulsivity could predict suicidal thoughts after controlling for mood instability. This study utilized longitudinal data from the 2000 Adult Psychiatric Morbidity Survey (N = 2,406). There was a time interval of 18 months between the two waves of the study. Trait impulsivity and mood instability were measured with the Structured Clinical Interview for DSM-IV Axis II Personality Disorders. Logistic regression analyses were used to evaluate baseline impulsivity and mood instability as predictors of future suicidal thoughts. Impulsivity significantly predicted the presence of suicidal thoughts, but this effect became non-significant with mood instability included in the same model. Impulsivity may be a redundant concept when predicting future suicidal thoughts if mood instability is considered. The significance is that research and therapy focusing on mood instability along with impulsivity may be useful in treating the suicidal patient. Mood instability and impulsivity both predict future suicidal thoughts. Impulsivity does not predict suicidal thoughts after controlling for mood instability. Assessing and treating mood instability could be important aspects of suicide prevention and risk management. © 2015 The British Psychological Society.

"Impulsive" youth suicide attempters are not necessarily all that impulsive.

PubMed

Witte, Tracy K; Merrill, Katherine A; Stellrecht, Nadia E; Bernert, Rebecca A; Hollar, Daniel L; Schatschneider, Christopher; Joiner, Thomas E

2008-04-01

The relationship between impulsivity and suicide has been conceptualized in the literature as a direct one. In contrast, Joiner's [Joiner, T.E., 2005. Why people die by suicide. Harvard University Press, Cambridge, MA.] theory posits that this relationship is indirect in that impulsive individuals are more likely to engage in suicidal behavior because impulsivity makes one more likely to be exposed to painful and provocative stimuli. Adolescents were selected from the Youth Risk Behavior Survey (YRBS) sample between the years of 1993-2003 who had planned for a suicide attempt but did not actually attempt (n=5685), who did not plan but did attempt ("impulsive attempters;" n=1172), and who both planned and attempted (n=4807). Items were selected from the YRBS to assess demographic variables, suicidal behaviors, and impulsive behaviors. Participants who had planned suicide without attempting were significantly less impulsive than those who had attempted without planning and than those who had both planned and attempted. Crucially, participants who had made a suicide attempt without prior planning were less impulsive than those who had planned and attempted. We were unable to conduct a multi-method assessment (i.e., measures were self-report); the measure of impulsivity consisted of items pulled from the YRBS rather than a previously validated impulsivity measure. The notion that the most impulsive individuals are more likely to plan for suicide attempts is an important one for many reasons both theoretical and clinical, including that it may refine risk assessment and attendant clinical decision-making.

Relationship of impulsivity and depression during early methamphetamine withdrawal in Han Chinese population.

PubMed

Zhang, Jie; Su, Hang; Tao, Jingyan; Xie, Ying; Sun, Yeming; Li, Liren; Zhang, Xiang Yang; Hu, Zhenyu; He, Jincai

2015-04-01

High level of impulsivity as well as depression is thought to be involved in the maintenance and development of methamphetamine (METH) addiction. However, the relationship between impulsivity and depression has not been studied thoroughly in METH dependence subjects, especially in early METH abstinent subjects. In this study, our objective is to explore the interplay between the depressive symptoms and impulsivity in early METH abstinent subjects. A total of 182 early abstinent METH dependent subjects (abstinence for 1-7 days) were recruited and the level of impulsivity was measured by the Barratt Impulsiveness Scale (BIS-11). Depressive symptoms and anxiety symptoms were assessed by the short 13-item Beck Depression Inventory (BDI-13) and Beck Anxiety Inventory (BAI) respectively. Global impulsivity of BIS-11 was significantly correlated with depressive symptoms among early METH abstinent subjects (r=0.283, p=0.001). Moreover, all subscales of BIS-11 were also found to be correlated with depressive symptoms: correlation with attentional impulsivity (r=0.202, p=0.006); correlation with motor impulsivity (r=0.267, p=0.001); and correlation with non-planning impulsivity (r=0.177, p=0.017). This study showed a relationship between impulsivity and depression, which may further the comprehension of motivational elements contributing to the maintenance and development of METH use disorder. Future research would be dedicated to exploring underlying mechanisms of association between impulsivity and depression. Copyright © 2014 Elsevier Ltd. All rights reserved.

Does impulsivity predict outcome in treatment for binge eating disorder? A multimodal investigation.

PubMed

Manasse, Stephanie M; Espel, Hallie M; Schumacher, Leah M; Kerrigan, Stephanie G; Zhang, Fengqing; Forman, Evan M; Juarascio, Adrienne S

2016-10-01

Multiple dimensions of impulsivity (e.g., affect-driven impulsivity, impulsive inhibition - both general and food-specific, and impulsive decision-making) are associated with binge eating pathology cross-sectionally, yet the literature on whether impulsivity predicts treatment outcome is limited. The present pilot study explored impulsivity-related predictors of 20-week outcome in a small open trial (n = 17) of a novel treatment for binge eating disorder. Overall, dimensions of impulsivity related to emotions (i.e., negative urgency) and food cues emerged as predictors of treatment outcomes (i.e., binge eating frequency and global eating pathology as measured by the Eating Disorders Examination), while more general measures of impulsivity were statistically unrelated to global eating pathology or binge frequency. Specifically, those with higher levels of negative urgency at baseline experienced slower and less pronounced benefit from treatment, and those with higher food-specific impulsivity had more severe global eating pathology at baseline that was consistent at post-treatment and follow-up. These preliminary findings suggest that patients high in negative urgency and with poor response inhibition to food cues may benefit from augmentation of existing treatments to achieve optimal outcomes. Future research will benefit from replication with a larger sample, parsing out the role of different dimensions of impulsivity in treatment outcome for eating disorders, and identifying how treatment can be improved to accommodate higher levels of baseline impulsivity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Barratt Impulsivity and Neural Regulation of Physiological Arousal.

PubMed

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

2015-01-01

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

Normative data on angular vestibulo-ocular responses in the yaw axis measured using the video head impulse test.

PubMed

Matiño-Soler, Eusebi; Esteller-More, Eduard; Martin-Sanchez, Juan-Carlos; Martinez-Sanchez, Jose-M; Perez-Fernandez, Nicolas

2015-03-01

To analyze vestibulo-ocular responses using the video head impulse test in the yaw axis. Prospective. Tertiary and university hospital. Two hundred twelve healthy subjects with no history of vestibular or neurologic impairment. Video head impulse test in the lateral semicircular canal plane. Vestibulo-ocular reflex (VOR) gain and appearance of refixation saccades (RSs) considering sex, age, and head impulse velocity and direction. Mean gain was 1.06 ± 0.07, and there were no differences between sexes. For all the impulses (n = 9,654; 4,947 rightward and 4,707 leftward), VOR gain decreased as head impulse velocity increased. When gain was evaluated by age and head velocity, it was steady until age 70 years for higher-velocity impulses and until age 90 years for lower-velocity head impulses. RSs were detected in 52 subjects, occurring after impulses to both sides of the head in 22 of these subjects. The number of subjects with RSs was significantly higher after age 71 years, and velocity was correlated, not with age, but with head impulse velocity. VOR gain was stable until age 90 years and thereafter dropped. However, this decrease occurred progressively in younger subjects as head impulse velocity increased, with VOR gain for faster head impulses decreasing significantly in subjects older than 70 years. This finding, in addition to the appearance of RSs, can be explained by the effect of aging on the deterioration of the vestibular system in the semicircular canals.

Motor impulsivity differentiates between psychiatric inpatients with multiple versus single lifetime suicide attempts.

PubMed

Colborn, Victoria A; LaCroix, Jessica M; Neely, Laura L; Tucker, Jennifer; Perera, Kanchana; Daruwala, Samantha E; Grammer, Geoffrey; Weaver, Jennifer; Ghahramanlou-Holloway, Marjan

2017-07-01

A history of multiple suicide attempts conveys greater risk for suicide than a single attempt. Impulsivity may partially explain the association between multiple attempts and increased risk. We examined trait impulsivity, ability to engage in goal-directed behaviors, and impulse control among psychiatrically hospitalized United States military personnel and their dependents. Individuals with a history of multiple versus single attempts had significantly higher motor impulsivity, indicating spur of the moment action. Providers are encouraged to directly assess and treat motor impulsivity among suicidal individuals. Further research should explore whether motor impulsivity is a mechanism of change in psychosocial suicide prevention interventions. Copyright © 2017. Published by Elsevier B.V.

Razumikhin-Type Stability Criteria for Differential Equations with Delayed Impulses.

PubMed

Wang, Qing; Zhu, Quanxin

2013-01-01

This paper studies stability problems of general impulsive differential equations where time delays occur in both differential and difference equations. Based on the method of Lyapunov functions, Razumikhin technique and mathematical induction, several stability criteria are obtained for differential equations with delayed impulses. Our results show that some systems with delayed impulses may be exponentially stabilized by impulses even if the system matrices are unstable. Some less restrictive sufficient conditions are also given to keep the good stability property of systems subject to certain type of impulsive perturbations. Examples with numerical simulations are discussed to illustrate the theorems. Our results may be applied to complex problems where impulses depend on both current and past states.

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

ERIC Educational Resources Information Center

Cyders, Melissa A.

2013-01-01

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

Dissecting Impulsivity and its Relationships to Drug Addictions

PubMed Central

Ashenhurst, James R.; Cervantes, M. Catalina; James, Alexander S.; Groman, Stephanie M.; Pennington, Zachary T.

2015-01-01

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

Assessing personal financial management in patients with bipolar disorder and its relation to impulsivity and response inhibition.

PubMed

Cheema, Marvi K; MacQueen, Glenda M; Hassel, Stefanie

2015-01-01

Impulsivity and risk-taking behaviours are reported in bipolar disorder (BD). We examined whether financial management skills are related to impulsivity in patients with BD. We assessed financial management skills using the Executive Personal Finance Scale (EPFS), impulsivity using the Barratt Impulsiveness Scale (BIS) and response inhibition using an emotional go/no-go task in bipolar individuals (N = 21) and healthy controls (HC; N = 23). Patients had fewer financial management skills and higher levels of impulsivity than HC. In patients and controls, increased impulsivity was associated with poorer personal financial management. Patients and HC performed equally on the emotional go/no-go task. Higher BIS scores were associated with faster reaction times in HC. In patients, however, higher BIS scores were associated with slower reaction times, possibly indicating compensatory cognitive strategies to counter increased impulsivity. Patients with BD may have reduced abilities to manage personal finances, when compared against healthy participants. Difficulty with personal finance management may arise in part as a result of increased levels of impulsivity. Patients may learn to compensate for increased impulsivity by modulating response times in our experimental situations although whether such compensatory strategies generalize to real-world situations is unknown.

The short (S) allele of the serotonin transporter polymorphism and acute tryptophan depletion both increase impulsivity in men.

PubMed

Walderhaug, Espen; Herman, Aryeh Isaac; Magnusson, Andres; Morgan, Michael John; Landrø, Nils Inge

2010-04-12

Reduced serotonergic neurotransmission is implicated in impulsive behavior. We studied the triallelic system of the serotonin transporter gene linked polymorphic region (5-HTTLPR) and acute manipulation of serotonin together to further delineate the mechanisms by which serotonergic neurotransmission affects impulsivity. Fifty-two healthy participants (38 men and 14 women) underwent acute tryptophan depletion (ATD) or placebo in a randomized, double-blind, parallel group experiment. Impulsive response style was measured on two versions of the Continuous Performance Task (CPT), and calculated using signal detection theory. We observed a dose-dependent effect for the short (S') allele of the 5-HTTLPR on impulsive response style. Individuals who had the S'/S' genotype were more impulsive than individuals with the L/S' genotype. Participants with the L/S' genotype were more impulsive than those with the L/L genotype. ATD increased impulsivity in men, and decreased impulsivity in women. These data demonstrate for the first time that reduced serotonergic tone as a result of either 5-HTTLPR genotype, or experimental ATD, are both independently and additively, associated with elevated impulsive response style in Caucasian men. Copyright (c) 2010 Elsevier Ireland Ltd. All rights reserved.

Impulsive noise of printers: measurement metrics and their subjective correlation

NASA Astrophysics Data System (ADS)

Baird, Terrence; Otto, Norman; Bray, Wade; Stephan, Mike

2005-09-01

In the office and home computing environments, printer impulsive noise has become a significant contributor to user perceived quality or lack thereof, and can affect the user's comfort level and ability to concentrate. Understanding and quantifying meaningful metrics for printer impulsivity is becoming an increasingly important goal for printer manufacturers. Several methods exist in international standards for measuring the impulsivity of noise. For information technology equipment (ITE), the method for detection of impulsive noise is provided in ECMA-74 and ISO 7779. However, there is a general acknowledgement that the current standard method of determining impulsivity by simply measuring A-weighted sound pressure level (SPL) with the impulsive time weighting, I, applied is inadequate to characterize impulsive noise and ultimately to predict user satisfaction and acceptance. In recent years, there has been a variety of new measurement methods evaluated for impulsive noise for both environmental and machinery noise. This paper reviews several of the available metrics, applies the metrics to several printer impulsive noise sources, and makes an initial assessment of their correlation to the subjective impressions of users. It is a review and continuation of the work presented at InterNoise 2005 (Baird, Bray, and Otto).

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

PubMed

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

2013-05-01

Impulse control disorders are a psychiatric condition characterized by the failure to resist an impulsive act or behavior that may be harmful to self or others. In movement disorders, impulse control disorders are associated with dopaminergic treatment, notably dopamine agonists (DAs). Impulse control disorders have been studied extensively in Parkinson's disease, but are also recognized in restless leg syndrome and atypical Parkinsonian syndromes. Epidemiological studies suggest younger age, male sex, greater novelty seeking, impulsivity, depression and premorbid impulse control disorders as the most consistent risk factors. Such patients may warrant special monitoring after starting treatment with a DA. Various individual screening tools are available for people without Parkinson's disease. The Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease has been developed specifically for Parkinson's disease. The best treatment for impulse control disorders is prevention. However, after the development of impulse control disorders, the mainstay intervention is to reduce or discontinue the offending anti-Parkinsonian medication. In refractory cases, other pharmacological interventions are available, including neuroleptics, antiepileptics, amantadine, antiandrogens, lithium and opioid antagonists. Unfortunately, their use is only supported by case reports, small case series or open-label clinical studies. Prospective, controlled studies are warranted. Ongoing investigations include naltrexone and nicotine.

Impulsive behavior in adults with attention deficit/ hyperactivity disorder: characterization of attentional, motor and cognitive impulsiveness.

PubMed

Malloy-Diniz, L; Fuentes, D; Leite, W Borges; Correa, H; Bechara, A

2007-07-01

Attention-deficit/hyperactivity disorder (ADHD) is characterized by inattention and/or hyperactivity/impulsivity. Impulsivity persists in adults with ADHD and might be the basis of much of the impairment observed in the daily lives of such individuals. The objective of this study was to address the presence, and more importantly, the three dimensions of impulsivity: attentional, non-planning and motor, in how they may relate to neuropsychological mechanisms of impulse control. We studied a sample of 50 adults with ADHD and 51 healthy comparison controls using the Barratt Impulsivity Scale Version 11 (BIS), and neuropsychological tasks, namely the Continuous Performance Task (CPT-II) and the Iowa Gambling Task (IGT). The ADHD group showed more signs of impulsivity on the three dimensions of BIS, committed more errors of omission and commission on the CPT-II, and made more disadvantageous choices on the IGT. These results support the existence of deficits related to three components of impulsivity: motor, cognitive, and attentional among adults with ADHD. Most importantly, this study also highlights the complementary nature of self-report questionnaires and neuropsychological tasks in the assessment of impulsivity in ADHD adults.

Genetic association of impulsivity in young adults: a multivariate study

PubMed Central

Khadka, S; Narayanan, B; Meda, S A; Gelernter, J; Han, S; Sawyer, B; Aslanzadeh, F; Stevens, M C; Hawkins, K A; Anticevic, A; Potenza, M N; Pearlson, G D

2014-01-01

Impulsivity is a heritable, multifaceted construct with clinically relevant links to multiple psychopathologies. We assessed impulsivity in young adult (N~2100) participants in a longitudinal study, using self-report questionnaires and computer-based behavioral tasks. Analysis was restricted to the subset (N=426) who underwent genotyping. Multivariate association between impulsivity measures and single-nucleotide polymorphism data was implemented using parallel independent component analysis (Para-ICA). Pathways associated with multiple genes in components that correlated significantly with impulsivity phenotypes were then identified using a pathway enrichment analysis. Para-ICA revealed two significantly correlated genotype–phenotype component pairs. One impulsivity component included the reward responsiveness subscale and behavioral inhibition scale of the Behavioral-Inhibition System/Behavioral-Activation System scale, and the second impulsivity component included the non-planning subscale of the Barratt Impulsiveness Scale and the Experiential Discounting Task. Pathway analysis identified processes related to neurogenesis, nervous system signal generation/amplification, neurotransmission and immune response. We identified various genes and gene regulatory pathways associated with empirically derived impulsivity components. Our study suggests that gene networks implicated previously in brain development, neurotransmission and immune response are related to impulsive tendencies and behaviors. PMID:25268255

Neurocognitive and psychiatric dimensions of “hot” impulsivity, but not “cool” impulsivity, predict HIV sexual risk behaviors among drug users in protracted abstinence

PubMed Central

Wilson, Michael J.; Vassileva, Jasmin

2016-01-01

Background Impulsivity is an important risk factor for HIV risky drug and sexual behaviors. Research identifies “hot” (i.e., affectively-mediated, reward-based) and “cool” (motoric, attentional, independent of context) neurocognitive and psychiatric dimensions of impulsivity, though the impact of specific drugs of abuse on these varieties of impulsivity remains an open question. Objectives The present study examined the associations of neurocognitive and psychiatric varieties of “hot” and “cool” impulsivity with measures of lifetime and recent sexual risk behaviors among users of different classes of drugs. Methods The study sample was comprised drug users in protracted (>1yr) abstinence: heroin monodependent (n=61), amphetamine monodependent (n=44), and polysubstance dependent (n= 73). “Hot” impulsivity was operationalized via neurocognitive tasks of reward-based decision-making and symptoms of psychopathy. “Cool” impulsivity was operationalized via neurocognitive tasks of response inhibition and symptoms of ADHD. Results “Hot” impulsivity was associated with sexual risk behaviors among heroin and amphetamine users in protracted abstinence, whereas “cool” impulsivity was not associated with sexual risk behaviors among any drug-using group. Neurocognitive “hot” impulsivity was associated with recent (past 30-day) sexual risk behaviors, whereas psychopathy was associated with sexual risk behaviors during more remote time-periods (past 6 month and lifetime) and mediated the association between heroin dependence and past 6-month sexual risk behaviors. Conclusion Assessments and interventions aimed at reducing sexual risk behaviors among drug users should focus on “hot” neurocognitive and psychiatric dimensions of impulsivity, such as decision-making and psychopathy. “Cool” dimensions of impulsivity such as response inhibition and ADHD were not related to sexual risk behaviors among drug users in protracted abstinence. PMID:26837332

Being impulsive and obese increases susceptibility to speeded detection of high-calorie foods.

PubMed

Bongers, Peggy; van de Giessen, Elsmarieke; Roefs, Anne; Nederkoorn, Chantal; Booij, Jan; van den Brink, Wim; Jansen, Anita

2015-06-01

Overeating and obesity are associated with impulsivity. In studies among patients with a substance use disorder, impulsivity was found to be associated with substance-related attentional bias. This study examined whether obesity, impulsivity and food craving are associated with an attentional bias for high-calorie food. Obese (n = 185, mean BMI = 38.18 ± 6.17) and matched healthy-weight (n = 134, mean BMI = 22.35 ± 1.63) men (27.9%) and women (72.1%), aged 18-45 years, took part in the study. Participants were tested on several self-report and behavioral measures of impulsivity (i.e., response inhibition and reward sensitivity) and self-reported trait craving. In addition, they performed a visual search task to measure attentional bias for high- and low-caloric foods. Self-reported impulsivity influenced the relationship between weight status and detection speed of high- and low-caloric food items: High-impulsive participants with obesity were significantly faster than high-impulsive healthy-weight participants in detecting a high-caloric food item among neutral items, whereas no such difference was observed among low-impulsive participants. No significant effects were found on low-caloric food items, for trait craving or any of the behavioral measures of impulsivity. Self-reported impulsivity, but not trait craving or behavioral measures of impulsivity, is associated with an attentional bias for high-caloric foods, but only in people with obesity. It is in particular the speedy detection of high-caloric foods in the environment that characterizes the impulsive person with obesity, which in turn may cause risky eating patterns in a society were high-caloric food is overly present. (c) 2015 APA, all rights reserved).

Dopaminergic modulation of the orbitofrontal cortex affects attention, motivation and impulsive responding in rats performing the five-choice serial reaction time task.

PubMed

Winstanley, Catharine A; Zeeb, Fiona D; Bedard, Amanda; Fu, Kent; Lai, Barbara; Steele, Christina; Wong, Adeline C

2010-07-11

Understanding the neurobiological factors underlying individual differences in impulsivity may provide valuable insight into vulnerability to impulse control disorders. Recent data implicate both the orbitofrontal cortex (OFC) and the dopaminergic system in psychiatric disorders associated with high levels of impulsivity, including substance abuse, mania and obsessive-compulsive disorder. However, the consequences of modulating dopaminergic activity within the OFC on impulsive behaviour are largely unknown. The effects of direct intra-OFC infusions of agonists and antagonists at the dopamine D(1) and D(2) receptors were therefore assessed in rats performing the five-choice serial reaction time test (5CSRT) of attention and motor impulsivity. Intra-OFC administration of SCH23390, a D(1) receptor antagonist, decreased impulsive responding in highly impulsive (HI) rats, but did not affect behaviour in less impulsive (LI) animals. Furthermore, the D(2) agonist quinpirole caused significant deficits in task performance, impairing accuracy, increasing omissions and decreasing the number of trials completed, which resembled the effects of systemic administration. In contrast, the D(1) agonist SKF 81297 had little effect on behaviour. Neither agonist increased impulsivity. These data provide partial support for the suggestion that high levels of impulsivity are associated with increased dopamine levels within the OFC, but further indicate that simulating dopamine's actions selectively at the D(1) or D(2) receptor cannot reproduce a highly impulsive phenotype. Dopaminergic activity within the OFC may therefore modulate impulsivity indirectly, perhaps in conjunction with other neurotransmitter systems. Furthermore, D(2)-mediated neurotransmission within the OFC could make a more fundamental contribution to cognitive behaviour. Copyright 2010 Elsevier B.V. All rights reserved.

[Impulsiveness Among Short-Term Prisoners with Antisocial Personality Disorder].

PubMed

Lang, Fabian U; Otte, Stefanie; Vasic, Nenad; Jäger, Markus; Dudeck, Manuela

2015-07-01

The study aimed to investigate the correlation between impulsiveness and the antisocial personality disorder among short-term prisoners. The impulsiveness was diagnosed by the Barratt Impulsiveness Scale (BIS). Short-term prisoners with antisocial personality disorder scored significant higher marks on the BIS total scale than those without any personality disorder. In detail, they scored higher marks on each subscale regarding attentional, motor and nonplanning impulsiveness. Moderate and high effects were calculated. It is to be considered to regard impulsivity as a conceptual component of antisociality. © Georg Thieme Verlag KG Stuttgart · New York.

Optical Enhancement of Degraded Fingerprints.

DTIC Science & Technology

1986-05-01

system. The integral 00 g(x,y) = ff f ( Cn)h(x-C,y-n)d dn -00 is the convolution operation g(x,y)=f(x,y)*h(x,y) where h(x,y) is the impulse response...periodic ridges on the left (1-) and right (2--) sides of the fingerprint in Figure 3-1 as periodic impulse -sheets (an impulse -sheet is a one...transformation of uniformly spaced, parallel impulse -sheets is a string of impulses (an impulse is a two-dimensional Dirac delta function, i.e. f(x,y) = 6(x,y

Self-reported impulsivity in Huntington's disease patients and relationship to executive dysfunction and reward responsiveness.

PubMed

Johnson, Patricia L; Potts, Geoffrey F; Sanchez-Ramos, Juan; Cimino, Cynthia R

2017-09-01

Few studies have directly investigated impulsivity in Huntington's disease (HD) despite known changes in dopaminergic and frontal functioning, changes that have been associated with impulsivity in other disorders and in the normal population. This study sought to further categorize impulsivity in HD through examining differences in self-reported impulsivity between community controls and HD patients, the relationship between executive dysfunction and impulsivity, and the relationship of a reward/punishment behavioral inhibition task in relation to these self-report measures. It was expected that HD patients would report higher impulsivity and executive dysfunction and that these measures would relate to a reward/punishment behavioral inhibition task. The Barratt Impulsivity Scale (BIS-11) and Behavioral Inhibition/Behavioral Activation Scale (BIS/BAS) were completed, and the Mini-Mental State Examination (MMSE) and a reward-based flanker task with punishing and rewarding conditions were administered to 22 HD patients and 14 control participants. HD patients reported higher trait impulsivity (BIS-11) and executive dysfunction (Frontal Systems Behavior Scale, FrSBE) but not increased impulsivity on the BIS/BAS relative to controls. Higher BIS-11 scores were related to increased self-reported executive dysfunction and the attention/working memory factor of the MMSE. On a reward/punishment behavioral inhibition task, BAS was uniquely related to increased accuracy on rewarding trials of the flanker task, but was not related to punishing trials in HD patients. The relationships found suggest that trait impulsivity is reported higher in HD and may not be driven by altered reward evaluation and the appetitive nature of stimuli but rather by increased executive dysfunction and lack of sensitivity to punishment. Impulsivity in HD may represent a combination of trait impulsivity, altered dopaminergic circuitry, and executive dysfunction. Understanding impulsivity in HD is important as it is related to increased risk to the patient and difficult behaviors for the caregiver, and sheds light on the disease process.

Mechanisms of Individual Differences in Impulsive and Risky Choice in Rats

PubMed Central

Kirkpatrick, Kimberly; Marshall, Andrew T.; Smith, Aaron P.

2016-01-01

Individual differences in impulsive and risky choice are key risk factors for a variety of maladaptive behaviors such as drug abuse, gambling, and obesity. In our rat model, ordered individual differences are stable across choice parameters, months of testing, and span a broad spectrum, suggesting that rats, like humans, exhibit trait-level impulsive and risky choice behaviors. In addition, impulsive and risky choices are highly correlated, suggesting a degree of correlation between these two traits. An examination of the underlying cognitive mechanisms has suggested an important role for timing processes in impulsive choice. In addition, in an examination of genetic factors in impulsive choice, the Lewis rat strain emerged as a possible animal model for studying disordered impulsive choice, with this strain demonstrating deficient delay processing. Early rearing environment also affected impulsive behaviors, with rearing in an enriched environment promoting adaptable and more self-controlled choices. The combined results with impulsive choice suggest an important role for timing and reward sensitivity in moderating impulsive behaviors. Relative reward valuation also affects risky choice, with manipulation of objective reward value (relative to an alternative reference point) resulting in loss chasing behaviors that predicted overall risky choice behaviors. The combined results are discussed in relation to domain-specific versus domain-general subjective reward valuation processes and the potential neural substrates of impulsive and risky choice. PMID:27695580

Impulsive social influence increases impulsive choices on a temporal discounting task in young adults.

PubMed

Gilman, Jodi M; Curran, Max T; Calderon, Vanessa; Stoeckel, Luke E; Evins, A Eden

2014-01-01

Adolescents and young adults who affiliate with friends who engage in impulsive behavior are more likely to engage in impulsive behaviors themselves, and those who associate with prosocial (i.e. more prudent, future oriented) peers are more likely to engage in prosocial behavior. However, it is difficult to disentangle the contribution of peer influence vs. peer selection (i.e., whether individuals choose friends with similar traits) when interpreting social behaviors. In this study, we combined a novel social manipulation with a well-validated delay discounting task assessing impulsive behavior to create a social influence delay discounting task, in which participants were exposed to both impulsive (smaller, sooner or SS payment) and non-impulsive (larger, later or LL payment) choices from their peers. Young adults in this sample, n = 51, aged 18-25 had a higher rate of SS choices after exposure to impulsive peer influence than after exposure to non-impulsive peer influence. Interestingly, in highly susceptible individuals, the rate of non-impulsive choices did not increase after exposure to non-impulsive influence. There was a positive correlation between self-reported suggestibility and degree of peer influence on SS choices. These results suggest that, in young adults, SS choices appear to be influenced by the choices of same-aged peers, especially for individuals who are highly susceptible to influence.

Impulsive Social Influence Increases Impulsive Choices on a Temporal Discounting Task in Young Adults

PubMed Central

Gilman, Jodi M.; Curran, Max T.; Calderon, Vanessa; Stoeckel, Luke E.; Evins, A. Eden

2014-01-01

Adolescents and young adults who affiliate with friends who engage in impulsive behavior are more likely to engage in impulsive behaviors themselves, and those who associate with prosocial (i.e. more prudent, future oriented) peers are more likely to engage in prosocial behavior. However, it is difficult to disentangle the contribution of peer influence vs. peer selection (i.e., whether individuals choose friends with similar traits) when interpreting social behaviors. In this study, we combined a novel social manipulation with a well-validated delay discounting task assessing impulsive behavior to create a social influence delay discounting task, in which participants were exposed to both impulsive (smaller, sooner or SS payment) and non-impulsive (larger, later or LL payment) choices from their peers. Young adults in this sample, n = 51, aged 18–25 had a higher rate of SS choices after exposure to impulsive peer influence than after exposure to non-impulsive peer influence. Interestingly, in highly susceptible individuals, the rate of non-impulsive choices did not increase after exposure to non-impulsive influence. There was a positive correlation between self-reported suggestibility and degree of peer influence on SS choices. These results suggest that, in young adults, SS choices appear to be influenced by the choices of same-aged peers, especially for individuals who are highly susceptible to influence. PMID:24988440

Is the Relationship Between ADHD Symptoms and Binge Eating Mediated by Impulsivity?

PubMed

Steadman, Kylie M; Knouse, Laura E

2016-11-01

Individuals with ADHD may be at risk of developing binge eating disorder (BED). Impulsivity correlates with both BED and ADHD; however, more research is needed to explore whether impulsivity plays an underlying role in the observed relationship between ADHD and BED. Questionnaires were used to assess ADHD and BED symptoms. Multiple questionnaires and a behavioral task were used to assess impulsivity in undiagnosed undergraduate participants (n = 50). Expected correlations were found among ADHD symptoms, BED tendencies, and measures of impulsivity with the exception of impulsivity on the behavioral task and BED symptoms; however, none of the measures of impulsivity were found to be significant mediators between ADHD and BED symptoms. Although impulsivity may play an important role in the interrelationship of ADHD and binge eating, other factors may also be critical in the development of this comorbidity. Investigation of this research question in clinical samples is needed. © The Author(s) 2014.

Subjective field study of response to impulsive helicopter noise

NASA Technical Reports Server (NTRS)

Powell, C. A.

1981-01-01

Subjects, located outdoors and indoors, judged the noisiness and other subjective noise characteristics of flyovers of two helicopters and a propeller driven airplane as part of a study of the effects of impulsiveness on the subjective response to helicopter noise. In the first experiment, the impulsive characteristics of one helicopter was controlled by varying the main rotor speed while maintaining a constant airspeed in level flight. The second experiment which utilized only the helicopters, included descent and level flight operations. The more impulsive helicopter was consistently judged less noisy than the less impulsive helicopter at equal effective perceived noise levels (EPNL). The ability of EPNL to predict noisiness was not improved by the addition of either of two proposed impulse corrections. A subjective measure of impulsiveness, however, which was not significantly related to the proposed impulse corrections, was found to improve the predictive ability of EPNL.

The slant of the forehead as a craniofacial feature of impulsiveness.

PubMed

Guerrero-Apolo, J David; Navarro-Pastor, J Blas; Bulbena-Vilarrasa, Antonio; Gabarre-Mir, Julián

2018-03-12

Impulsiveness has been the subject of much research, but little is known about the possible relationship between craniofacial anatomy and impulsiveness. The present study was designed to investigate the relationship between one aspect of craniofacial structure (the angle of inclination of the forehead) and impulsiveness. Photographs in profile were obtained from 131 volunteers who had been fined for driving at high speed and were undergoing a court-mandated driving license point-recovery course. They completed the Barratt Impulsiveness Scale (BIS-11), the Impulsive Behavior Scale (UPPS-P), and Zuckerman's Sensation Seeking Scale (V). The angle of the slant of the forehead was measured with a photographic support and a protractor. High positive concordance was found between forehead inclination and 14 out of the 15 impulsiveness factors studied. The angle of inclination of the forehead was significantly associated with self-reported impulsiveness in this sample of traffic violators.

Sleep patterns and impulse control among Japanese junior high school students.

PubMed

Abe, Takeru; Hagihara, Akihito; Nobutomo, Koichi

2010-10-01

Adolescents with decreased impulse control exhibit behavioral problems. Lifestyles are related to impulse control. However, the relations of sleep patterns and impulse control among adolescents are unknown. Thus we examined how sleep patterns were associated with impulse control among Japanese junior high school students. Surveys were completed by a nationwide sample of 1934 students. A significant association between decreased impulse control and bedtimes after midnight was revealed. Specific lifestyle factors related to bedtimes after midnight were older age, greater numbers of hours spent watching television, lack of participation in an extracurricular activity, greater use of convenience stores, and increased attendance at cram schools. This study revealed that going to sleep after midnight was significantly related to decreased impulse control among adolescents. Data about specific lifestyle factors related to going to sleep after midnight should be useful in preventing those behaviors demonstrated by school children that derive from decreased impulse control.

Impulsive Effects on Quasi-Synchronization of Neural Networks With Parameter Mismatches and Time-Varying Delay.

PubMed

Tang, Ze; Park, Ju H; Feng, Jianwen

2018-04-01

This paper is concerned with the exponential synchronization issue of nonidentically coupled neural networks with time-varying delay. Due to the parameter mismatch phenomena existed in neural networks, the problem of quasi-synchronization is thus discussed by applying some impulsive control strategies. Based on the definition of average impulsive interval and the extended comparison principle for impulsive systems, some criteria for achieving the quasi-synchronization of neural networks are derived. More extensive ranges of impulsive effects are discussed so that impulse could either play an effective role or play an adverse role in the final network synchronization. In addition, according to the extended formula for the variation of parameters with time-varying delay, precisely exponential convergence rates and quasi-synchronization errors are obtained, respectively, in view of different types impulsive effects. Finally, some numerical simulations with different types of impulsive effects are presented to illustrate the effectiveness of theoretical analysis.

The Effect of Implicit Preferences on Food Consumption: Moderating Role of Ego Depletion and Impulsivity

PubMed Central

Wang, Yan; Zhu, Jinglei; Hu, Yi; Fang, Yuan; Wang, Guosen; Cui, Xianghua; Wang, Lei

2016-01-01

Ego depletion has been found to moderate the effect of implicit preferences on food consumption, such that implicit preferences predict consumption only under a depleted state. The present study tested how trait impulsivity impacts the effect of implicit preferences on food consumption in a depleted condition. Trait impulsivity was measured by means of self-report and a stop signal task. Results showed that both self-reported impulsivity and behavioral impulsivity moderated the ‘depletion and then eating according to implicit preferences’ effect, albeit in different ways. Participants high in self-reported impulsivity and low in behavioral impulsivity were more vulnerable to the effect of depletion on eating. The implications of these results for extant theories are discussed. Future research is needed to verify whether or not trait impulsivity is associated with vulnerability to depletion across different self-control domains. PMID:27881966

Genetics of impulsive behaviour

PubMed Central

Bevilacqua, Laura; Goldman, David

2013-01-01

Impulsivity, defined as the tendency to act without foresight, comprises a multitude of constructs and is associated with a variety of psychiatric disorders. Dissecting different aspects of impulsive behaviour and relating these to specific neurobiological circuits would improve our understanding of the etiology of complex behaviours for which impulsivity is key, and advance genetic studies in this behavioural domain. In this review, we will discuss the heritability of some impulsivity constructs and their possible use as endophenotypes (heritable, disease-associated intermediate phenotypes). Several functional genetic variants associated with impulsive behaviour have been identified by the candidate gene approach and re-sequencing, and whole genome strategies can be implemented for discovery of novel rare and common alleles influencing impulsivity. Via deep sequencing an uncommon HTR2B stop codon, common in one population, was discovered, with implications for understanding impulsive behaviour in both humans and rodents and for future gene discovery. PMID:23440466

ImpulseDE: detection of differentially expressed genes in time series data using impulse models.

PubMed

Sander, Jil; Schultze, Joachim L; Yosef, Nir

2017-03-01

Perturbations in the environment lead to distinctive gene expression changes within a cell. Observed over time, those variations can be characterized by single impulse-like progression patterns. ImpulseDE is an R package suited to capture these patterns in high throughput time series datasets. By fitting a representative impulse model to each gene, it reports differentially expressed genes across time points from a single or between two time courses from two experiments. To optimize running time, the code uses clustering and multi-threading. By applying ImpulseDE , we demonstrate its power to represent underlying biology of gene expression in microarray and RNA-Seq data. ImpulseDE is available on Bioconductor ( https://bioconductor.org/packages/ImpulseDE/ ). niryosef@berkeley.edu. Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com

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

PubMed

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

2010-04-01

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

Impulsivity in self-mutilative behavior: psychometric and biological findings.

PubMed

Herpertz, S; Sass, H; Favazza, A

1997-01-01

This paper examines impulsivity as a central factor in moderate/superficial self-mutilation such as skin-cutting and burning. A sample of 165 subjects were divided into four groups, namely self-mutilators, patients with any modes of impulsive behavior other than self-mutilation, patients without any impulsive behavior, and normal probands. All were administered the 10th version of the Barratt Impulsiveness Scale, the State-Trait Anger Expression Inventory, and the Inventory for the Assessment of Factors of Aggressiveness. They also were interviewed carefully in regards to both impulsive and self-mutilative behavior. A d-fenfluramine challenge test was administered to 36 females and prolactin levels were measured. On the whole results implicate impulsive personality functioning as a major factor in subjects with moderate/superficial self-mutilative behavior whose trait pathology is similar to personality disordered patients with other modes of self-harming impulsive behavior.

A computational study of laser-supported detonation waves propagating up an oblique incident beam

NASA Astrophysics Data System (ADS)

Bohn, C. L.; Crawford, M. L.

1987-01-01

A series of numerical experiments was conducted to study the propagation of laser-supported detonation waves (LSDWs) in the case that a CO2 laser beam strikes an aluminum surface obliquely in air. A reflected shock formed at the aluminum surface was more prominent at higher angles of incidence theta of the beam, but otherwise the hydrodynamics of the plasma and the LSDW were insensitive to theta. Furthermore, the total impulse delivered to the aluminum varied approximately as 1/cos theta, a result that can be modeled with elementary blast-wave theory.

Experimental test of the mechanism of reaction for (e,e'p) coincidence experiment. [/sup 12/C(e,e'p): DWIA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernheim, M.; Bussiere, A.; Frullani, S.

1977-06-27

In order to test the validity of the distorted wave impulse approximation to describe (e,e'p) reactions and/or the suitability of the available optical potential parameters to calculate the distortion, the spectral function was measured for /sub 12/C(e,e'p)/sub 11/B in different kinematical configurations. Experimental results are shown together with the distributions computed with several values of the optical potential parameters. Data seem to indicate the necessity of using different parameters for p hole states and s hole states.

Geometry of the diffusive propagation region in the August 14, 1982 solar electron event

NASA Technical Reports Server (NTRS)

Evenson, P. A.

1985-01-01

On August 14, 1982, relativistic electrons arrived promptly after an impulsive gamma ray flare, indicating that very little scattering was taking place in interplanetary space. By ignoring anisotropy data the time profile of the event is well described by interplanetary diffusion except for the derived particle injection time. This discrepancy provides independent evidence that the particles are diffusing in a volume close to the Sun rather than in interplanetary space. The flux at maximum method of determining the number of particles produced is still a good approximation when appropriately applied.

Continuum analyzing power for 4He(p-->,p') at 100 MeV

NASA Astrophysics Data System (ADS)

Lawrie, J. J.; Whittal, D. M.; Cowley, A. A.

1990-08-01

Distorted-wave impulse approximation calculations of the continuum analyzing power for the inclusive reaction 4He(p-->,p') at an incident energy of 100 MeV are presented. In addition to the quasifree knockout of nucleons, contributions from the knockout of deuteron, triton, and helion clusters are taken into account, together with a breakup component. Whereas nucleon knockout by itself does not account for the experimentally observed analyzing power, the inclusion of clusters has a large effect. Thus a simple knockout model is able to provide a reasonable description of the experimental continuum analyzing power.

A fully programmable 100-spin coherent Ising machine with all-to-all connections

NASA Astrophysics Data System (ADS)

McMahon, Peter; Marandi, Alireza; Haribara, Yoshitaka; Hamerly, Ryan; Langrock, Carsten; Tamate, Shuhei; Inagaki, Takahiro; Takesue, Hiroki; Utsunomiya, Shoko; Aihara, Kazuyuki; Byer, Robert; Fejer, Martin; Mabuchi, Hideo; Yamamoto, Yoshihisa

We present a scalable optical processor with electronic feedback, based on networks of optical parametric oscillators. The design of our machine is inspired by adiabatic quantum computers, although it is not an AQC itself. Our prototype machine is able to find exact solutions of, or sample good approximate solutions to, a variety of hard instances of Ising problems with up to 100 spins and 10,000 spin-spin connections. This research was funded by the Impulsing Paradigm Change through Disruptive Technologies (ImPACT) Program of the Council of Science, Technology and Innovation (Cabinet Office, Government of Japan).

Multiobjective Optimization of Low-Energy Trajectories Using Optimal Control on Dynamical Channels

NASA Technical Reports Server (NTRS)

Coffee, Thomas M.; Anderson, Rodney L.; Lo, Martin W.

2011-01-01

We introduce a computational method to design efficient low-energy trajectories by extracting initial solutions from dynamical channels formed by invariant manifolds, and improving these solutions through variational optimal control. We consider trajectories connecting two unstable periodic orbits in the circular restricted 3-body problem (CR3BP). Our method leverages dynamical channels to generate a range of solutions, and approximates the areto front for impulse and time of flight through a multiobjective optimization of these solutions based on primer vector theory. We demonstrate the application of our method to a libration orbit transfer in the Earth-Moon system.

Neural pulse frequency modulation of an exponentially correlated Gaussian process

NASA Technical Reports Server (NTRS)

Hutchinson, C. E.; Chon, Y.-T.

1976-01-01

The effect of NPFM (Neural Pulse Frequency Modulation) on a stationary Gaussian input, namely an exponentially correlated Gaussian input, is investigated with special emphasis on the determination of the average number of pulses in unit time, known also as the average frequency of pulse occurrence. For some classes of stationary input processes where the formulation of the appropriate multidimensional Markov diffusion model of the input-plus-NPFM system is possible, the average impulse frequency may be obtained by a generalization of the approach adopted. The results are approximate and numerical, but are in close agreement with Monte Carlo computer simulation results.

Biophysical applications of neutron Compton scattering

NASA Astrophysics Data System (ADS)

Wanderlingh, U. N.; Albergamo, F.; Hayward, R. L.; Middendorf, H. D.

Neutron Compton scattering (NCS) can be applied to measuring nuclear momentum distributions and potential parameters in molecules of biophysical interest. We discuss the analysis of NCS spectra from peptide models, focusing on the characterisation of the amide proton dynamics in terms of the width of the H-bond potential well, its Laplacian, and the mean kinetic energy of the proton. The Sears expansion is used to quantify deviations from the high-Q limit (impulse approximation), and line-shape asymmetry parameters are evaluated in terms of Hermite polynomials. Results on NCS from selectively deuterated acetanilide are used to illustrate this approach.

Impulsivity Trajectories and Gambling in Adolescence among Urban Male Youth

PubMed Central

Liu, Weiwei; Lee, Grace P.; Goldweber, Asha; Petras, Hanno; Storr, Carla L.; Ialongo, Nicholas S.; Martins, Silvia S.

2012-01-01

Aim Building on the recent emerging literature on the impulsivity trajectory-gambling association, this study investigated the association between developmental trajectories of teacher-rated impulsivity in early adolescence (ages 11–15) and subsequent gambling and gambling problems (i.e. at-risk and problem gambling) by age 19. Design Prospective cohort design. Setting Urban communities in Baltimore, Maryland. Participants The sample consists of 310 predominately minority (87%) and low SES (70%) males followed from first grade to late adolescence. Measurements Impulsivity was measured using teacher ratings of classroom behavior. Self-reported gambling behavior was assessed using the South Oaks Gambling Screen-Revised for Adolescents (SOGS-RA). Findings Results from a conventional growth model suggest the intercept of the impulsivity development (as measured by the repeated assessments of impulsivity across the entire developmental period) was significantly associated with gambling. Results from a general growth mixture model evidenced two distinct trajectories: a high impulsivity trajectory (41% the sample) and a low impulsivity trajectory (59% of the sample). Despite its non-significant association with any gambling, heterogeneity in impulsivity development was significantly associated with gambling problems. Specifically, being in the high impulsivity trajectory doubled the odds of meeting criteria for at-risk or problem gambling (OR= 2.09[1.02, 4.27]) and tripled the odds of meeting criteria for problem gambling (OR=2.84[1.02, 7.91]) Conclusions Development in impulsivity is strongly associated with problem/at-risk gambling in adolescence among urban male youth. Findings highlight the importance of distinguishing gambling problems from any gambling when evaluating programs aimed at reducing youth gambling problems through reducing impulsivity. PMID:23130867

THE RELATIONSHIP BETWEEN MEASURES OF IMPULSIVITY AND ALCOHOL MISUSE: AN INTEGRATIVE STRUCTURAL EQUATION MODELING APPROACH

PubMed Central

Courtney, Kelly E.; Arellano, Ryan; Barkley-Levenson, Emily; Gálvan, Adriana; Poldrack, Russell A.; MacKillop, James; Jentsch, J. David; Ray, Lara A.

2011-01-01

Background Higher levels of impulsivity have been implicated in the development of alcohol use disorders. Recent findings suggest that impulsivity is not a unitary construct, highlighted by the diverse ways in which the various measures of impulsivity relate to alcohol use outcomes. This study simultaneously tested the following dimensions of impulsivity as determinants of alcohol use and alcohol problems: risky decision-making, self-reported risk attitudes, response inhibition, and impulsive decision-making. Method Participants were a community sample of non-treatment seeking problem drinkers (N = 158). Structural Equation Modeling (SEM) analyses employed behavioral measures of impulsive decision-making (Delay Discounting Task, DDT), response inhibition (Stop Signal Task, SST), and risky decision-making (Balloon Analogue Risk Task, BART), and a self-report measure of risk attitudes (Domain-specific Risk-attitude Scale, DOSPERT), as predictors of alcohol use and of alcohol-related problems in this sample. Results The model fit well, accounting for 38% of the variance in alcohol problems, and identified two impulsivity dimensions that significantly loaded onto alcohol outcomes: (1) impulsive decision-making, indexed by the DDT; and (2) risky decision-making, measured by the BART. Conclusions The impulsive decision-making dimension of impulsivity, indexed by the DDT, was the strongest predictor of alcohol use and alcohol pathology in this sample of problem drinkers. Unexpectedly, a negative relationship was found between risky decision-making and alcohol problems. The results highlight the importance of considering the distinct facets of impulsivity in order to elucidate their individual and combined effects on alcohol use initiation, escalation, and dependence. PMID:22091877

Latent class analysis of eating and impulsive behavioral symptoms in Taiwanese women with bulimia nervosa.

PubMed

Tseng, Mei-Chih Meg; Hu, Fu-Chang

2012-01-01

The implications of impulsivity in its relationship with binge-eating or purging behaviors remain unclear. This study examined the patterns of eating behaviors and co-morbid impulsive behaviors in individuals with bulimia nervosa n optimally homogeneous classes using latent class analysis (LCA). All participants (n=180) were asked to complete a series of self-reported inventories of impulsive behaviors and other psychological measures. Information regarding the lifetime presence of symptoms of eating disorder was assessed by clinical interviews. LCA was conducted using eating disorder symptoms, impulsive behaviors, and the number of purging methods. Three latent classes of bulimic women were identified. These were women who exhibited relatively higher rates of purging, symptoms of impulsive behavior, and multiple purging methods (17.8%), women who used no more than one purging method with a low occurrence of impulsive behavior (41.7%), and women who showed higher rates of purging behaviors and the use of multiple purging methods with a low rate of impulsive behavior (41.7%). The impulsive sub-group had comparable severity of eating-related measures, frequency of binge-eating, and higher levels of general psychopathology than that of the other two sub-groups. This study provides empirical support for the existence of an impulsive subgroup with distinctive features among a non-Western group of BN patients. This study also suggests that mechanisms other than impulse dysregulation may exist for the development of binge-eating and purging behaviors in bulimia nervosa patients, or the mechanisms contributing to binge-eating and impulsive behaviors may be different. Copyright © 2011 Elsevier Inc. All rights reserved.

Dark personality traits and impulsivity among adolescents: Differential links to problem behaviors and family relations.

PubMed

Dubas, Judith Semon; Baams, Laura; Doornwaard, Suzan M; van Aken, Marcel A G

2017-10-01

Research on how dark personality traits develop and relate to risky behaviors and family relations during adolescence is scarce. This study used a person-oriented approach to examine (a) whether distinct groups of adolescents could be identified based on their developmental profiles of callous-unemotional (CU), grandiose manipulative (GM), and dysfunctional impulsivity (DI) traits and (b) whether these groups differ in their problem behaviors and parent-adolescent relationship quality. Latent class growth analyses on 4-wave data of 1,131 Dutch adolescents revealed 3 personality profiles: (1) a dark impulsive group (13.9%), with high scores on all 3 traits (CU, GM, and DI) that were stable over time; (2) an impulsive group (26.1%), with high and increasing levels of impulsivity and relatively low scores on CU and GM; and (3) and a low risk group (60.0%), with relatively low levels on all 3 personality characteristics, with impulsivity decreasing over time. Compared with adolescents in the low risk group, adolescents in the dark impulsive and impulsive groups reported higher initial levels of substance use, sexual risk behaviors, permissive sexual attitudes, parent-adolescent conflict, and lower parent-adolescent satisfaction, as well as greater increases in sexual risk behavior over time. Compared with adolescents in the impulsive group, those in the dark impulsive group showed the highest levels of risk behaviors. Hence, dark personality traits coupled with impulsivity may be indicative of an earlier and more severe trajectory of problem behaviors that may differ from the trajectory of youth who are only impulsive. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Subscales of the Barratt Impulsiveness Scale differentially relate to the Big Five factors of personality.

PubMed

Lange, Florian; Wagner, Adina; Müller, Astrid; Eggert, Frank

2017-06-01

The place of impulsiveness in multidimensional personality frameworks is still unclear. In particular, no consensus has yet been reached with regard to the relation of impulsiveness to Neuroticism and Extraversion. We aim to contribute to a clearer understanding of these relationships by accounting for the multidimensional structure of impulsiveness. In three independent studies, we related the subscales of the Barratt Impulsiveness Scale (BIS) to the Big Five factors of personality. Study 1 investigated the associations between the BIS subscales and the Big Five factors as measured by the NEO Five-Factor Inventory (NEO-FFI) in a student sample (N = 113). Selective positive correlations emerged between motor impulsiveness and Extraversion and between attentional impulsiveness and Neuroticism. This pattern of results was replicated in Study 2 (N = 132) using a 10-item short version of the Big Five Inventory. In Study 3, we analyzed BIS and NEO-FFI data obtained from a sample of patients with pathological buying (N = 68). In these patients, the relationship between motor impulsiveness and Extraversion was significantly weakened when compared to the non-clinical samples. At the same time, the relationship between attentional impulsiveness and Neuroticism was substantially stronger in the clinical sample. Our studies highlight the utility of the BIS subscales for clarifying the relationship between impulsiveness and the Big Five personality factors. We conclude that impulsiveness might occupy multiple places in multidimensional personality frameworks, which need to be specified to improve the interpretability of impulsiveness scales. © 2017 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Multidimensional Assessment of Impulsivity in Relation to Obesity and Food Addiction

PubMed Central

VanderBroek-Stice, Lauren; Stojek, Monika K.; Beach, Steven R. H.; vanDellen, Michelle R.; MacKillop, James

2017-01-01

Based on similarities between overconsumption of food and addictive drugs, there is increasing interest in “food addiction,” a compulsive eating pattern defined using symptoms parallel to substance use disorders. Impulsivity, a multidimensional construct robustly linked to drug addiction, has been increasingly examined as an obesity determinant, but with mixed findings. This study sought to clarify relations between three major domains of impulsivity (i.e., impulsive personality traits, discounting of delayed rewards, and behavioral inhibition) in both obesity and food addiction. Based on the association between impulsivity and compulsive drug use, the general hypothesis was that the impulsivity-food addiction relation would be stronger than and responsible for the impulsivity-obesity relation. Using a cross-sectional dimensional design, participants (N = 181; 32% obese) completed a biometric assessment, the Yale Food Addiction Scale (YFAS), the UPPS-P Impulsive Behavior Scales, a Go/NoGo task, and measures of monetary delay discounting. Results revealed significantly higher prevalence of food addiction among obese participants and stronger zero-order associations between impulsivity indices and YFAS compared to obesity. Two aspects of impulsivity were independently significantly associated with food addiction: (a) a composite of Positive and Negative Urgency, reflecting proneness to act impulsively during intense mood states, and (b) steep discounting of delayed rewards. Furthermore, the results supported food addiction as a mediator connecting both urgency and delay discounting with obesity. These findings provide further evidence linking impulsivity to food addiction and obesity, and suggest that food addiction may be a candidate etiological pathway to obesity for individuals exhibiting elevations in these domains. PMID:28087369

Multidimensional assessment of impulsivity in relation to obesity and food addiction.

PubMed

VanderBroek-Stice, Lauren; Stojek, Monika K; Beach, Steven R H; vanDellen, Michelle R; MacKillop, James

2017-05-01

Based on similarities between overconsumption of food and addictive drugs, there is increasing interest in "food addiction," a compulsive eating pattern defined using symptoms parallel to substance use disorders. Impulsivity, a multidimensional construct robustly linked to drug addiction, has been increasingly examined as an obesity determinant, but with mixed findings. This study sought to clarify relations between three major domains of impulsivity (i.e., impulsive personality traits, discounting of delayed rewards, and behavioral inhibition) in both obesity and food addiction. Based on the association between impulsivity and compulsive drug use, the general hypothesis was that the impulsivity-food addiction relation would be stronger than and responsible for the impulsivity-obesity relation. Using a cross-sectional dimensional design, participants (N = 181; 32% obese) completed a biometric assessment, the Yale Food Addiction Scale (YFAS), the UPPS-P Impulsive Behavior Scales, a Go/NoGo task, and measures of monetary delay discounting. Results revealed significantly higher prevalence of food addiction among obese participants and stronger zero-order associations between impulsivity indices and YFAS compared to obesity. Two aspects of impulsivity were independently significantly associated with food addiction: (a) a composite of Positive and Negative Urgency, reflecting proneness to act impulsively during intense mood states, and (b) steep discounting of delayed rewards. Furthermore, the results supported food addiction as a mediator connecting both urgency and delay discounting with obesity. These findings provide further evidence linking impulsivity to food addiction and obesity, and suggest that food addiction may be a candidate etiological pathway to obesity for individuals exhibiting elevations in these domains. Copyright © 2017 Elsevier Ltd. All rights reserved.

A meta-analytic review of the relationship between adolescent risky sexual behavior and impulsivity across gender, age, and race.

PubMed

Dir, Allyson L; Coskunpinar, Ayca; Cyders, Melissa A

2014-11-01

Impulsivity is frequently included as a risk factor in models of adolescent sexual risk-taking; however, findings on the magnitude of association between impulsivity and risky sexual behavior are variable across studies. The aims of the current meta-analysis were to examine (1) how specific impulsivity traits relate to specific risky sexual behaviors in adolescents, and (2) how the impulsivity-risky sex relationship might differ across gender, age, and race. Eighty-one studies were meta-analyzed using a random effects model to examine the overall impulsivity-risky sex relationship and relationships among specific impulsivity traits and risky sexual behaviors. Overall, results revealed a significant, yet small, association between impulsivity and adolescent risky sexual behavior (r=0.19, p<0.001) that did not differ across impulsivity trait. A pattern of stronger effects was associated with risky sexual behaviors as compared to negative outcomes related to these behaviors. Gender moderated the overall relationship (β=0.22, p=0.04), such that effect sizes were significantly larger in samples with more females. Age, race, study design, and sample type did not moderate the relationship, although there was a pattern suggesting smaller effects for adolescents in juvenile detention settings. Adolescent samples with more females showed a larger impulsivity-risky sex relationship, suggesting that impulsivity may be a more important risk factor for risky sex among adolescent females. Research and treatment should consider gender differences when investigating the role of impulsivity in adolescent sexual risk-taking. Copyright © 2014 Elsevier Ltd. All rights reserved.

The 5-HTTLPR polymorphism, impulsivity and suicide behavior in euthymic bipolar patients.

PubMed

Malloy-Diniz, Leandro Fernandes; Neves, Fernando Silva; de Moraes, Paulo Henrique Paiva; De Marco, Luiz Armando; Romano-Silva, Marco Aurélio; Krebs, Marie-Odile; Corrêa, Humberto

2011-09-01

Suicide behavior is very frequent in Bipolar Disorder (BD) and they are both closely associated with impulsivity. Furthermore they are, impulsivity, BD and suicide behavior, associated with serotonergic function, at least partially, under genetic determinism and somewhat associated with the serotonin transporter gene polymorphism, the 5-HTTLPR. We aimed to assess different impulsivity components in BD sub-grouped by suicidal attempt and healthy controls. We hypothesized that the non-planning/cognitive impulsivity, could be more closely associated with suicidal behavior. We further associated 5-HTTLPR genotypes with neuropsychological results to test the hypothesis that this polymorphism is associated with cognitive impulsivity. We assessed 95 euthymic bipolar patients sub-grouped by suicidal attempt history in comparison with 94 healthy controls. All subjects underwent a laboratory assessment of impulsivity (Continuous Performance Test and Iowa Gambling Test). Furthermore the genotyping of 5-HTTLPR was performed in all subjects. We found that bipolar patients are more impulsive than healthy controls in all impulsivity dimensions we studied. Furthermore bipolar patients with a suicide attempt history have a greater cognitive impulsivity when compared to both bipolar patients without such a history as well when compared to healthy controls. No association was found between 5-HTTLPR genotypes and neuropsychological measures of impulsive behavior. The sample studied can be considered small and a potentially confounding variable - medication status - was not controlled. A lifetime suicide attempt seems associated with cognitive impulsivity independently of the socio-demographic and clinical variables studied as well with 5-HTTLPR genotype. Further studies in larger samples are necessary. Copyright © 2011 Elsevier B.V. All rights reserved.

Progesterone attenuates impulsive action in a Go/No-Go task for sucrose pellets in female and male rats

PubMed Central

Swalve, Natashia; Smethells, John R.; Carroll, Marilyn E.

2016-01-01

Impulsivity, or a tendency to act without anticipation of future consequences, is associated with drug abuse. Impulsivity is typically separated into two main measures, impulsive action and impulsive choice. Given the association of impulsivity and drug abuse, treatments that reduce impulsivity have been proposed as an effective method for countering drug addiction. Progesterone has emerged as a promising treatment, as it is associated with decreased addiction-related behaviors and impulsive action. The goal of the present study was to determine the effects of progesterone (PRO) on impulsive action for food: a Go/No-Go task. Female and male rats responded for sucrose pellets during a Go component when lever pressing was reinforced on a variable-interval 30-s schedule. During the alternate No-Go component, withholding a lever press was reinforced on a differential reinforcement of other (DRO) behavior 30-s schedule, where a lever press reset the DRO timer. Impulsive action was operationally defined as the inability to withhold a response during the No-Go component (i.e. the number of DRO resets). Once Go/No-Go behavior was stable, responding between rats treated with PRO (0.5 mg/kg) or vehicle was examined. Progesterone significantly decreased the total number of DRO resets in both males and females, but it did not affect VI responding for sucrose pellets. This suggests that PRO decreases motor impulsivity for sucrose pellets without affecting motivation for food. Thus, PRO may reduce motor impulsivity, a behavior underlying drug addiction. PMID:27497836

Effects of smoking abstinence on impulsive behavior among smokers high and low in ADHD-like symptoms

PubMed Central

Hawk, Larry W.

2011-01-01

Rationale Impulsivity, a multifaceted construct that includes inhibitory control and heightened preference for immediate reward, is central to models of drug use and abuse. Within a self-medication framework, abstinence from smoking may lead to an increase in impulsive behavior and the likelihood of relapse, particularly among persons with disorders (e.g., attention-deficit/hyperactivity disorder, ADHD) and personality traits (e.g., impulsivity) linked to impulsive behavior. Objectives This study aimed to examine the effects of smoking abstinence on multiple measures of impulsivity among a non-clinical sample of adult smokers selected for high and low levels of ADHD symptoms. Methods In a within-subjects design, participants selected for high or low levels of self-reported ADHD symptoms (N=56) completed sessions following overnight abstinence and when smoking as usual (order counterbalanced). Measures of impulsive behavior included response inhibition (i.e., stop signal task), interference control (i.e., attentional modification of prepulse inhibition (PPI) of startle), and impulsive choice (i.e., hypothetical delay discounting). Results As hypothesized, abstinence decreased response inhibition and PPI. Although ADHD symptoms moderated abstinence effects on impulsive choice and response inhibition, the pattern was opposite to our predictions: the low-ADHD group responded more impulsively when abstinent, whereas the high-ADHD group was relatively unaffected by abstinence. Conclusions These findings highlight the importance of utilizing multiple laboratory measures to examine a multifactorial construct such as impulsive behavior and raise questions about how best to assess symptoms of ADHD and impulsivity among non-abstinent smokers. PMID:21559802

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

PubMed

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

2015-03-01

Research indicates a significant relationship between posttraumatic stress disorder (PTSD) and anger (Olatunji, Ciesielski, & Tolin, 2010; Orth & Wieland, 2006). Individuals may seek urgent coping to deal with the distress of anger, which is a mobilizing and action-oriented emotion (Novaco & Chemtob, 2002); possibly in the form of impulsive actions consistent with impulsivity's association with anger (Milligan & Waller, 2001; Whiteside & Lynam, 2001). This could be 1 of the explanations for the relationship between PTSD and impulsivity (Kotler, Julian, Efront, & Amir, 2001; Ledgerwood & Petry, 2006). The present study assessed the mediating role of anger between PTSD (overall scores and subscales of arousal and negative alterations in mood/cognitions) and impulsivity, using gender as a covariate of impulsivity. The PTSD Checklist for Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5), Dimensions of Anger Reaction scale-5, and the UPPS Impulsivity Scale were administered to a sample of 244 undergraduate students with a trauma history. Results based on 1000 bootstrapped samples indicated significant direct effects of PTSD (overall and 2 subscales) on anger, of anger on impulsivity, and of PTSD (overall and 2 subscales) on impulsivity. Further, anger significantly mediated the relationship between PTSD (overall and 2 subscales) and impulsivity, consistent with the hypothesized models. Results suggest that impulsivity aims at coping with distressing anger, possibly explaining the presence of substance usage, and other impulsive behaviors in people with PTSD. Further, anger probably serves as a mobilizing and action-oriented emotion coupled with PTSD symptoms. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

Stability of uncertain impulsive complex-variable chaotic systems with time-varying delays.

PubMed

Zheng, Song

2015-09-01

In this paper, the robust exponential stabilization of uncertain impulsive complex-variable chaotic delayed systems is considered with parameters perturbation and delayed impulses. It is assumed that the considered complex-variable chaotic systems have bounded parametric uncertainties together with the state variables on the impulses related to the time-varying delays. Based on the theories of adaptive control and impulsive control, some less conservative and easily verified stability criteria are established for a class of complex-variable chaotic delayed systems with delayed impulses. Some numerical simulations are given to validate the effectiveness of the proposed criteria of impulsive stabilization for uncertain complex-variable chaotic delayed systems. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Impulsive EUV bursts observed in C IV with OSO-8. [UV solar spectra

NASA Technical Reports Server (NTRS)

Athay, R. G.; White, O. R.; Lites, B. W.; Bruner, E. C., Jr.

1980-01-01

Time sequences of profiles of the 1548 A line of C IV containing 51 EUV bursts observed in or near active regions are analyzed to determine the brightness, Doppler shift and line broadening characteristics of the bursts. The bursts have mean lifetimes of approximately 150 s, and mean increases in brightness at burst maximum of four-fold as observed with a field of view of 2 x 20 arc sec. Mean burst diameters are estimated to be 3 arc sec, or smaller. All but three of the bursts show Doppler shifts with velocities sometimes exceeding 75 km/s; 31 are dominated by red shifts and 17 are dominated by blue shifts. Approximately half of the latter group have red-shifted precursors. The bursts are interpreted as prominence material, such as surges and coronal rain, moving through the field of view of the spectrometer.

Limiting vibration in systems with constant amplitude actuators through command preshaping. M.S Thesis - MIT

NASA Technical Reports Server (NTRS)

Rogers, Keith Eric

1994-01-01

The basic concepts of command preshaping were taken and adapted to the framework of systems with constant amplitude (on-off) actuators. In this context, pulse sequences were developed which help to attenuate vibration in flexible systems with high robustness to errors in frequency identification. Sequences containing impulses of different magnitudes were approximated by sequences containing pulses of different durations. The effects of variation in pulse width on this approximation were examined. Sequences capable of minimizing loads induced in flexible systems during execution of commands were also investigated. The usefulness of these techniques in real-world situations was verified by application to a high fidelity simulation of the space shuttle. Results showed that constant amplitude preshaping techniques offer a substantial improvement in vibration reduction over both the standard and upgraded shuttle control methods and may be mission enabling for use of the shuttle with extremely massive payloads.

Prefrontal Cortex and Impulsive Decision Making

PubMed Central

Kim, Soyoun; Lee, Daeyeol

2010-01-01

Impulsivity refers to a set of heterogeneous behaviors that are tuned suboptimally along certain temporal dimensions. Impulsive inter-temporal choice refers to the tendency to forego a large but delayed reward and to seek an inferior but more immediate reward, whereas impulsive motor responses also result when the subjects fail to suppress inappropriate automatic behaviors. In addition, impulsive actions can be produced when too much emphasis is placed on speed rather than accuracy in a wide range of behaviors, including perceptual decision making. Despite this heterogeneous nature, the prefrontal cortex and its connected areas, such as the basal ganglia, play an important role in gating impulsive actions in a variety of behavioral tasks. Here, we describe key features of computations necessary for optimal decision making, and how their failures can lead to impulsive behaviors. We also review the recent findings from neuroimaging and single-neuron recording studies on the neural mechanisms related to impulsive behaviors. Converging approaches in economics, psychology, and neuroscience provide a unique vista for better understanding the nature of behavioral impairments associated with impulsivity. PMID:20728878

Rethinking impulsivity in suicide.

PubMed

Klonsky, E David; May, Alexis

2010-12-01

Elevated impulsivity is thought to facilitate the transition from suicidal thoughts to suicidal behavior. Therefore, impulsivity should distinguish those who have attempted suicide (attempters) from those who have only considered suicide (ideators-only). This hypothesis was examined in three large nonclinical samples: (1) 2,011 military recruits, (2) 1,296 college students, and (3) 399 high school students. In sample 1, contrary to traditional models of suicide risk, a unidimensional measure of impulsivity failed to distinguish attempters from ideators-only. In samples 2 and 3, which were administered a multidimensional measure of impulsivity (i.e., the UPPS impulsive behavior scale; Whiteside & Lynam, 2001), different impulsivity-related traits characterized attempters and ideators-only. Whereas both attempters and ideators-only exhibited high urgency (the tendency to act impulsive in the face of negative emotions), only attempters exhibited poor premeditation (a diminished ability to think through the consequences of one's actions). Neither attempters nor ideators-only exhibited high sensation seeking or lack of perseverance. Future research should continue to distinguish impulsivity-related traits that predict suicide ideation from those that predict suicide attempts, and models of suicide risk should be revised accordingly.

Impulsivity and the Modular Organization of Resting-State Neural Networks

PubMed Central

Davis, F. Caroline; Knodt, Annchen R.; Sporns, Olaf; Lahey, Benjamin B.; Zald, David H.; Brigidi, Bart D.; Hariri, Ahmad R.

2013-01-01

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. PMID:22645253

Posttraumatic Stress Disorder's Underlying Dimensions and Their Relation With Impulsivity Facets.

PubMed

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

2016-01-01

Research indicates a significant relationship between posttraumatic stress disorder (PTSD) and impulsivity (Kotler, Julian, Efront, and Amir, J Nerv Ment Dis 189:162-167, 2001; Ledgerwood and Petry, J Trauma Stress 19:411-416, 2006). The present study assessed relations between PTSD symptom clusters and impulsivity subscales in an effort to assess the specific impulsivity component most related to PTSD's alterations in arousal/reactivity and alterations in mood/cognitions symptoms. In the current study, the PTSD Checklist for Diagnostic and Statistical Manual of Mental Disorders, 5th Edition, and the UPPS Impulsivity Scale were administered to a sample of 412 nonclinical subjects with a trauma history. Results indicated that PTSD's alterations in arousal/reactivity and mood/cognition factors were most related to impulsivity's sensation-seeking tendency compared with other impulsivity components. Results highlight the importance of assessing and addressing (1) sensation-seeking tendencies and (2) urges to act impulsively when experiencing negative affect in trauma treatment. Furthermore, it is possible that sensation-seeking tendencies are primarily driving the comorbidity between PTSD and certain impulsive behaviors.

Age and impulsive behavior in drug addiction: A review of past research and future directions.

PubMed

Argyriou, Evangelia; Um, Miji; Carron, Claire; Cyders, Melissa A

2018-01-01

Impulsive behavior is implicated in the initiation, maintenance, and relapse of drug-seeking behaviors involved in drug addiction. Research shows that changes in impulsive behavior across the lifespan contribute to drug use and addiction. The goal of this review is to examine existing research on the relationship between impulsive behavior and drug use across the lifespan and to recommend directions for future research. Three domains of impulsive behavior are explored in this review: impulsive behavior-related personality traits, delay discounting, and prepotent response inhibition. First, we present previous research on these three domains of impulsive behavior and drug use across developmental stages. Then, we discuss how changes in impulsive behavior across the lifespan are implicated in the progression of drug use and addiction. Finally, we discuss the relatively limited attention given to middle-to-older adults in the current literature, consider the validity of the measures used to assess impulsive behavior in middle-to-older adulthood, and suggest recommendations for future research. Copyright © 2017 Elsevier Inc. All rights reserved.

On the flow generated by rotating flat plates of low aspect ratio

NASA Astrophysics Data System (ADS)

DeVoria, Adam C.

Low-aspect-ratio propulsors typically allow for high maneuverability at low-to-moderate speeds. This has made them the subject of much recent research aimed at employing such appendages on autonomous vehicles which are required to navigate tumultuous environments. This experimental investigation focuses on the fluid dynamic aspects associated with overly-simplified versions of such biologically-inspired propulsors. In doing so, fundamental contributions are made to the research area. The unsteady, three-dimensional flow of a low-aspect-ratio, trapezoidal flat plate undergoing rotation from rest at a 90° angle of attack and Reynolds numbers of O(103) is investigated experimentally. The objectives are to develop a straightforward protocol for vortex saturation, and to understand the effects of the root-to-tip flow for different velocity programs. The experiments are conducted in a glass-walled tank, and digital particle image velocimetry is used to obtain planar velocity measurements. A formation-parameter definition is investigated and is found to reasonably predict the state corresponding to the pinch-off of the initial tip vortex across the velocity programs tested. The flow in the region near the tip is relatively insensitive to Reynolds number over the range studied. The component normal to the plate is unaffected by total rotational amplitude while the tangential component has dependence on this angle. Also, an estimate of the first tip-vortex pinch-off time is obtained from the near-tip velocity data and agrees very well with values estimated using circulation. The angle of incidence of the bulk root-to-tip flow relative to the plate normal becomes more oblique with increasing rotational amplitude. Accordingly, the peak magnitude of the tangential velocity is also increased and as a result advects fluid momentum away from the plate at a higher rate. The more oblique impingement of the root-to-tip flow for increasing rotational amplitude is shown to have a distinct effect on the associated fluid dynamic force normal to the plate. For impulsive plate deceleration the time that a non-negligible force exists decreases, while for non-impulsive plate deceleration both this time and the relative force magnitude decrease for larger rotational amplitudes. In a separate set of experiments, force measurements are conducted on a similar plate that performs an advancing stroke from rest followed by a returning stroke. The parameters varied are the rotational amplitude of the motion and the rest time between the advancing and returning strokes. The unsteady normal forces track with the angular acceleration of the plate, with the added mass force peak in the returning stroke being larger than that in the advancing stroke. However, as the rest time is increased, the normal forces generated in each stroke become dynamically similar. The maximum total impulse is calculated from the force measurements and rapidly decays from its largest value at zero rest time and asymptotes to a constant with increased rest time. The direction of this impulse is also calculated and quickly approaches the direction about which the plate motion is symmetric. The largest additional impulse contribution obtained from executing a returning stroke within a finite time is approximately 18%. Increases in rotational amplitude initially increase the maximum total impulse, but it then plateaus at an amplitude of around 90 degrees. For non-zero rest times, any maxima of the impulse in a fixed direction are weak and necessarily reduced from the maximum possible impulse. For a nearly 100 degrees range of directions, the impulse is largest for rotational amplitudes between 75--90 degrees. The results are also applied to three types of propulsive configurations.

The effect of individual differences on adolescents' impulsive buying behavior.

PubMed

Lin, Chien-Huang; Chuang, Shin-Chieh

2005-01-01

This study posits a relationship between Emotional Intelligence (EI) and Impulsive Buying Tendency (IBT). A survey of 574 adolescents found that high-EI adolescents manifested less impulsive behavior than did low-EI adolescents, and high-IBT adolescents were more likely to engage in more impulsive buying behavior than were low-IBT adolescents. Finally, possible extensions of the research to the area of adolescents' impulsive buying are suggested.

[Assessment of functional and dysfunctional impulsivity in substance-addicted patients by means of Dickman's Inventory].

PubMed

Pedrero Pérez, Eduardo J

2009-11-01

Impulsivity is a dispositional trait consistently linked to addiction. Nevertheless, Dickman proposed two different types of impulsivity, a functional variant and another, dysfunctional one. Almost all studies in addiction have exclusively explored the dysfunctional facet of impulsivity. The main purpose of this study was to check the applicability of the Dickman Impulsivity Inventory to explore both types of impulsivity in addicted individuals. We applied a Spanish version of the inventory and studied its psychometric properties. We found adequate internal consistency, construct validity and convergence of measures with related instruments, both in non-clinical (N = 398) and in treated substance-addicted (diacetylmorphine, cocaine, alcohol and cannabis; N = 140) samples. Addicted individuals did not differ from the non-clinical population in their functional impulsivity, but we found a great effect size (eta2p = 0.35) in the differences when exploring the dysfunctional type, with higher scores in addicts. Dysfunctional impulsivity was related to dysexecutive symptoms (r2 = 0.39), and personality traits such as Novelty Seeking (r2 = 0.57), but not with the Exploratory Excitability subdimension (r2 = 0.01), this latter being more closely related to functional impulsivity (r2 = 0.16). Data support the usefulness of this inventory to estimate types of impulsivity related to the prevention and treatment of addictive behaviors.

Psychedelic symptoms of cannabis and cocaine use as a function of trait impulsivity.

PubMed

van Wel, J H P; Spronk, D B; Kuypers, K P C; Theunissen, E L; Toennes, S W; Verkes, R J; Ramaekers, J G

2015-03-01

Trait impulsivity has been linked to addiction in humans. It has been suggested that drug users with high trait impulsivity levels are more sensitive to subjective drug intoxication. This study assessed whether subjective response to drugs differs between drug users with normal or high levels of trait impulsivity. Regular drug users (N = 122) received doses of cocaine HCl, cannabis, and placebo in a three-way crossover study. Their mood, dissociative state, and psychedelic symptoms were measured with subjective rating scales (CADDS, Bowdle, POMS). Trait impulsivity was assessed with the Barratt Impulsiveness Scale. Cannabis increased dissociation and psychedelic state, as well as fatigue, confusion, depression and anxiety, and decreased arousal, positive mood, vigor, friendliness, and elation. Cocaine increased dissociation, psychedelic state, vigor, friendliness, elation, positive mood, anxiety and arousal, while decreasing fatigue. Only a few subjective items revealed a drug × trait impulsivity interaction, suggesting that psychedelic symptoms were most intense in high impulsivity subjects. Trait impulsiveness ratings were negatively correlated with ratings of vigor (r = -.197) and positively correlated with ratings of loss of thought control (r = .237) during cannabis intoxication. It is concluded that a broad association between trait impulsivity and psychedelic subjective drug experience appears to be absent. © The Author(s) 2015.

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

PubMed Central

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

2013-01-01

Impulse control disorders are a psychiatric condition characterized by the failure to resist an impulsive act or behavior that may be harmful to self or others. In movement disorders, impulse control disorders are associated with dopaminergic treatment, notably dopamine agonists (DAs). Impulse control disorders have been studied extensively in Parkinson’s disease, but are also recognized in restless leg syndrome and atypical Parkinsonian syndromes. Epidemiological studies suggest younger age, male sex, greater novelty seeking, impulsivity, depression and premorbid impulse control disorders as the most consistent risk factors. Such patients may warrant special monitoring after starting treatment with a DA. Various individual screening tools are available for people without Parkinson’s disease. The Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease has been developed specifically for Parkinson’s disease. The best treatment for impulse control disorders is prevention. However, after the development of impulse control disorders, the mainstay intervention is to reduce or discontinue the offending anti-Parkinsonian medication. In refractory cases, other pharmacological interventions are available, including neuroleptics, antiepileptics, amantadine, antiandrogens, lithium and opioid antagonists. Unfortunately, their use is only supported by case reports, small case series or open-label clinical studies. Prospective, controlled studies are warranted. Ongoing investigations include naltrexone and nicotine. PMID:23634190

Modelling impulsive factors for electronics and restaurant coupons’ e-store display

NASA Astrophysics Data System (ADS)

Ariningsih, P. K.; Nainggolan, M.; Sandy, I. A.

2018-04-01

In many times, the increment of e-store visitors does not followed by sales increment. Most purchases through e-commerce are impulsive buying, however only small amount of study is available to understand impulsive factors of e-store display. This paper suggests a preliminary concept on understanding the impulsive factors in Electronics and Restaurant Coupons e-store display, which are two among few popular group products sold through e-commerce. By conducting literature study and survey, 31 attributes were identified as impulsive factors in electronics e-store display and 20 attributes were identified as impulsive factors for restaurant coupon e-store. The attributes were then grouped into comprehensive impulsive factors by factor analysis. Each group of impulsive attributes were generated into 3 factors. Accessibility Factors and Trust Factors appeared for each group products. The other factors are Internal Factors for electronics e-store and Marketing factors for restaurant coupons e-store. Structural Equation Model of the impulsive factors was developed for each type of e-store, which stated the covariance between Trust Factors and Accessibility Factors. Based on preliminary model, Internal Factor and Trust Factor are influencing impulsive buying in electronics store. Special factor for electronics e-store is Internal Factor, while for restaurant coupons e-store is Marketing Factor.

Neural Correlates of Impulsivity in Healthy Males and Females with Family Histories of Alcoholism

PubMed Central

DeVito, Elise E; Meda, Shashwath A; Jiantonio, Rachel; Potenza, Marc N; Krystal, John H; Pearlson, Godfrey D

2013-01-01

Individuals family-history positive (FHP) for alcoholism have increased risk for the disorder, which may be mediated by intermediate behavioral traits such as impulsivity. Given the sex differences in the risk for and clinical presentation of addictive disorders, risk for addiction may be differentially mediated by impulsivity within FHP males and females. FHP (N=28) and family-history negative (FHN, N=31) healthy, non-substance-abusing adults completed an fMRI Go/No-Go task and were assessed on impulsivity and alcohol use. Effects of family history and sex were investigated as were associations between neural correlates of impulse control and out-of-scanner measures of impulsivity and alcohol use. FHP individuals showed greater activation in the left anterior insula and inferior frontal gyrus during successful inhibitions, an effect that was driven primarily by FHP males. Higher self-reported impulsivity and behavioral discounting impulsivity, but not alcohol use measures, were associated with greater BOLD signal in the region that differentiated the FHP and FHN groups. Impulsivity factors were associated with alcohol use measures across the FHP and FHN groups. These findings are consistent with increased risk for addiction among FHP individuals being conferred through disrupted function within neural systems important for impulse control. PMID:23584260

Role of Serotonin and Dopamine System Interactions in the Neurobiology of Impulsive Aggression and its Comorbidity with other Clinical Disorders

PubMed Central

Seo, Dongju; Patrick, Christopher J.; Kennealy, Patrick J.

2008-01-01

Impulsive aggression is characterized by an inability to regulate affect as well as aggressive impulses, and is highly comorbid with other mental disorders including depression, suicidal behavior, and substance abuse. In an effort to elucidate the neurobiological underpinnings of impulsive aggression and to help account for its connections with these other disorders, this paper reviews relevant biochemical, brain imaging, and genetic studies. The review suggests that dysfunctional interactions between serotonin and dopamine systems in the prefrontal cortex may be an important mechanism underlying the link between impulsive aggression and its comorbid disorders. Specifically, serotonin hypofunction may represent a biochemical trait that predisposes individuals to impulsive aggression, with dopamine hyperfunction contributing in an additive fashion to the serotonergic deficit. The current paper proposes a modified diathesis-stress model of impulsive aggression in which the underlying biological diathesis may be deficient serotonergic function in the ventral prefrontal cortex. This underlying disposition can be manifested behaviorally as impulsive aggression towards oneself and others, and as depression under precipitating life stressors. Substance abuse associated with impulsive aggression is understood in the context of dopamine dysregulation resulting from serotonergic deficiency. Also discussed are future research directions in the neurobiology of impulsive aggression and its comorbid disorders. PMID:19802333

The error-related negativity (ERN) is an electrophysiological marker of motor impulsiveness on the Barratt Impulsiveness Scale (BIS-11) during adolescence.

PubMed

Taylor, Jasmine B; Visser, Troy A W; Fueggle, Simone N; Bellgrove, Mark A; Fox, Allison M

2018-04-01

Previous studies have postulated that the error-related negativity (ERN) may reflect individual differences in impulsivity; however, none have used a longitudinal framework or evaluated impulsivity as a multidimensional construct. The current study evaluated whether ERN amplitude, measured in childhood and adolescence, is predictive of impulsiveness during adolescence. Seventy-five children participated in this study, initially at ages 7-9 years and again at 12-18 years. The interval between testing sessions ranged from 5 to 9 years. The ERN was extracted in response to behavioural errors produced during a modified visual flanker task at both time points (i.e. childhood and adolescence). Participants also completed the Barratt Impulsiveness Scale - a measure that considers impulsiveness to comprise three core sub-traits - during adolescence. At adolescence, the ERN amplitude was significantly larger than during childhood. Additionally, ERN amplitude during adolescence significantly predicted motor impulsiveness at that time point, after controlling for age, gender, and the number of trials included in the ERN. In contrast, ERN amplitude during childhood did not uniquely predict impulsiveness during adolescence. These findings provide preliminary evidence that ERN amplitude is an electrophysiological marker of self-reported motor impulsiveness (i.e. acting without thinking) during adolescence. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Association between Impulsivity and Weight Status in a General Population.

PubMed

Bénard, Marc; Camilleri, Géraldine M; Etilé, Fabrice; Méjean, Caroline; Bellisle, France; Reach, Gérard; Hercberg, Serge; Péneau, Sandrine

2017-03-01

The objective of this study is to examine the association between impulsivity and weight status in a large sample of the adult general population in France, and the influence of gender on this relationship. A total of 11,929 men and 39,114 women participating in the NutriNet-Santé cohort were selected in this cross-sectional analysis. The Barratt Impulsiveness Scale (BIS-11) was used to assess impulsivity. Weight and height were self-reported. The association between impulsivity and BMI was estimated using logistic regressions adjusted for socio-demographic and lifestyle factors. Individuals with high impulsivity levels (BIS-11 total score >71) were more likely to be obese (Odds Ratio (OR) = 1.80, 95% Confidence Interval (CI): 1.39, 2.33 in men; OR = 1.30, 95% CI: 1.15, 1.48 in women) compared to individuals in the average range of impulsivity. The strongest associations between impulsivity and obesity were observed in men, where highly impulsive participants were more likely to be class III obese (BMI > 40 kg/m²) (OR = 3.57, 95% CI: 1.86, 6.85). This large sample analysis supports the existence of a relationship between impulsivity and weight status and the importance of psychological factors in the prevention of obesity.

Dissociable Frontostriatal White Matter Connectivity Underlies Reward and Motor Impulsivity

PubMed Central

Hampton, William H.; Alm, Kylie H.; Venkatraman, Vinod; Nugiel, Tehila; Olson, Ingrid R.

2017-01-01

Dysfunction of cognitive control often leads to impulsive decision-making in clinical and healthy populations. Some research suggests that a generalized cognitive control mechanism underlies the ability to modulate various types of impulsive behavior, while other evidence suggests different forms of impulsivity are dissociable, and rely on distinct neural circuitry. Past research consistently implicates several brain regions, such as the striatum and portions of the prefrontal cortex, in impulsive behavior. However the ventral and dorsal striatum are distinct in regards to function and connectivity. Nascent evidence points to the importance of frontostriatal white matter connectivity in impulsivity, yet it remains unclear whether particular tracts relate to different control behaviors. Here we used probabilistic tractography of diffusion imaging data to relate ventral and dorsal frontostriatal connectivity to reward and motor impulsivity measures. We found a double dissociation such that individual differences in white matter connectivity between the ventral striatum and the ventromedial prefrontal cortex and dorsolateral prefrontal cortex was associated with reward impulsivity, as measured by delay discounting, whereas connectivity between dorsal striatum and supplementary motor area was associated with motor impulsivity, but not vice versa. Our findings suggest that (a) structural connectivity can is associated with a large amount of behavioral variation; (b) different types of impulsivity are driven by dissociable frontostriatal neural circuitry. PMID:28189592

Impulsivity and the 5-HTTLPR Polymorphism in a Non-Clinical Sample

PubMed Central

Lage, Guilherme M.; Malloy-Diniz, Leandro F.; Matos, Lorena O.; Bastos, Marisa A. R.; Abrantes, Suzana S. C.; Corrêa, Humberto

2011-01-01

Background Impulsivity has been associated with serotonergic system functions. However, few researchers have investigated the relationship between a polymorphism in the promoter of the serotonin transporter gene (5-HTTLPR) and the different components of impulsivity in a non-clinical population. The aim of this study was to investigate the relationship between a polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) and the different components of impulsivity in a non-clinical population. Methodology/Principal Findings We administered two neuropsychological tests, the Continuous Performance Task and the Iowa Gambling Task, to 127 healthy participants to measure their levels of motor, attentional and non-planning impulsivity. Then, these participants were grouped by genotype and gender, and their scores on impulsivity measures were compared. There were no significant differences between group scores on attentional, motor and non-planning impulsivity. Conclusions/Significance Our results suggest that 5-HTTLPR genotype is not significantly associated with subsets of impulsive behavior in a non-clinical sample when measured by neuropsychological tests. These findings are discussed in terms of the sensitivity of neuropsychological tests to detect impulsivity in a non-clinical population and the role of gender and race in the relationship between the 5-HTTLPR and impulsivity. PMID:21386887

The Role of Different Aspects of Impulsivity as Independent Risk Factors for Substance Use Disorders in Patients with ADHD: A Review.

PubMed

Ortal, Slobodin; van de Glind, Geurt; Johan, Franck; Itai, Berger; Nir, Yachin; Iliyan, Ivanov; van den Brink, Wim

2015-01-01

High impulsivity in children with attention deficit/hyperactivity disorder (ADHD) plays a key role in their vulnerability to substance abuse disorders (SUDs). Although impulsivity is increasingly recognized as a multidimensional construct, efforts to describe the contribution of different impulsivity aspects to the development of SUD have been hindered by conceptual and experimental inconsistencies. This review seeks to map potential trajectories from childhood ADHD to SUD by examining the hypothesized mediating role of three different impulsivity-related constructs: disinhibition, impulsive choice, and sensation seeking. Integration of data from developmental, cognitive, and neurophysiological research suggests that childhood ADHD and SUD are both associated with behavioural and neurophysiological deficits in all three impulsivity-related constructs. Examination of brain mechanisms related to the three impulsivity-related constructs indicates that ADHD share neurophysiological deficits with SUD, such as abnormal brain activity in areas involved in inhibition and complex cognitive-emotional processes. We conclude that different impulsivity constructs operate independently and interact with each other to affect adult risk taking behaviour and SUD in patients with childhood ADHD. This review highlights the current theoretical and methodological challenges in the study of impulsivity and discusses clinical implications and directions for future research.

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

PubMed

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

2013-12-01

Behavioral measures of impulsivity are widely used in substance abuse research, yet relatively little attention has been devoted to establishing their psychometric properties, especially their reliability over repeated administration. The current study examined the test-retest reliability of a battery of standardized behavioral impulsivity tasks, including measures of impulsive choice (i.e., delay discounting, probability discounting, and the Balloon Analogue Risk Task), impulsive action (i.e., the stop signal task, the go/no-go task, and commission errors on the continuous performance task), and inattention (i.e., attention lapses on a simple reaction time task and omission errors on the continuous performance task). Healthy adults (n = 128) performed the battery on two separate occasions. Reliability estimates for the individual tasks ranged from moderate to high, with Pearson correlations within the specific impulsivity domains as follows: impulsive choice (r range: .76-.89, ps < .001); impulsive action (r range: .65-.73, ps < .001); and inattention (r range: .38-.42, ps < .001). Additionally, the influence of day-to-day fluctuations in mood, as measured by the Profile of Mood States, was assessed in relation to variability in performance on each of the behavioral tasks. Change in performance on the delay discounting task was significantly associated with change in positive mood and arousal. No other behavioral measures were significantly associated with mood. In sum, the current analysis demonstrates that behavioral measures of impulsivity are reliable measures and thus can be confidently used to assess various facets of impulsivity as intermediate phenotypes for drug abuse.

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

PubMed

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

2015-10-01

Overweight children appear to be more responsive to environmental, hedonic cues and easily overeat in the current obesogenic environment. They are also found to overeat in the absence of hunger, and this overeating seems related to impulsivity: impulsive participants are more prone to external eating. However, some studies showed that impulsive adults are also more prone to hunger cues: impulsive participants overate especially when feeling hungry. This would mean impulsive people are more reactive to both external and internal cues. The overeating was limited to palatable high energy-dense foods: hunger made them fancy a snack. In the current study, we wanted to test the interaction between impulsivity, hunger and consumption of food type in children. Impulsivity was measured in 88 children between the ages of 7 and 9. Next, half of the participants performed a taste test before their own regular lunch and half of the participants immediately after their lunch. During the taste test, low, medium and high energy-dense food items were presented. Results showed that impulsive children ate more high energy-dense foods than low impulsive children, both before and after their lunch. No differences were found on low or medium energy-dense foods. Impulsive children therefore showed normal sensitivity for internal hunger and satiety cues, but abnormal response to high energy-dense foods. This might render them vulnerable to tasty temptation in the environment and to weight gain in their future. Copyright © 2015 Elsevier Ltd. All rights reserved.

Latent Impulsivity Subtypes in Substance Use Disorders and Interactions with Internalizing and Externalizing Co-Occurring Disorders

PubMed Central

Marín-Navarrete, Rodrigo; Toledo-Fernández, Aldebarán; Villalobos-Gallegos, Luis; Roncero, Carlos; Szerman, Nestor; Medina-Mora, María Elena

2018-01-01

This study explored the clinical importance of latent impulsivity subtypes within a sample of individuals with substance use disorders (SUDs) and high rates of co-occurring disorders (CODs) receiving residential treatment, aiming to assess the heterogeneity of the associations between SUDs and CODs across such impulsivity subtypes. The abbreviated Barratt impulsiveness scale was used to assess motor and cognitive (attentional and nonplanning) impulsivity, a structured interview for diagnosis of SUD and CODs, and other clinimetric measures for severity of substance use. Latent class analysis was conducted to extract subgroups of impulsivity subtypes and Poisson regression to analyze effects of interactions of classes by CODs on severity of substance use. 568 participants were evaluated. Results featured a four-class model as the best-fitted solution: overall high impulsivity (OHI); overall low impulsivity; high cognitive-low motor impulsivity; and moderate cognitive-low motor impulsivity (MC-LMI). OHI and MC-LMI concentrated on most of the individuals with CODs, and individuals within OHI and MC-LMI showed more severity of substance use. The expression of this severity relative to the impulsivity subtypes was modified by their interaction with internalizing and externalizing CODs in very heterogeneous ways. Our findings suggest that knowing either the presence of trait-based subtypes or CODs in individuals with SUDs is not enough to characterize clinical outcomes, and that the analysis of interactions between psychiatric categories and behavioral traits is necessary to better understand the expressions of psychiatric disorders. PMID:29479323

Impulsivity, risky behaviors and accidents in alcohol-dependent patients

PubMed Central

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

2013-01-01

Impulsivity and alcohol drinking are both considered as important predictors of unintentional as well as intentional injuries. However, relationships of impulsivity with risky behaviors and a history of accidents have not been investigated in alcohol dependence. The aim of this study was to analyze relationships between the frequency of risky behaviors and level of behavioral as well as cognitive impulsivity in alcohol-dependent patients. By means of Barratt’s Impulsiveness Scale (BIS) and stop-signal task, the levels of cognitive and behavioral impulsivity among 304 alcohol-dependent patients were measured. Also, patients were asked to answer questions from the Short Inventory of Problems applying to risky behaviors and accidents after alcohol drinking. In addition participants completed a questionnaire to assess frequency of other behaviors from the analyzed spectrum (use of other drugs, driving or aggressive behavior after alcohol drinking). The statistical analysis revealed a significant association between impulsivity and frequency of risky behaviors in alcohol-dependent patients. Individuals with higher scores in BIS behaved more frequently in a risky way and had significantly more accidents after alcohol drinking. The association with risky behaviors was strongest for non-planning and attentional impulsivity subscales, whereas frequency of accidents was particularly associated with motor impulsivity. A multivariate analysis revealed that impulsivity was the most important predictor of risky behaviors, but did not significantly predict a history of accidents. Our study confirms that impulsivity is an important correlate of risky behaviors in alcohol-dependent individuals, along with global psychopathology and severity of alcohol dependence. PMID:23246707

Integrative Understanding of Familial Impulsivity, Early Adversity and Suicide Risk.

PubMed

Lima, Isabela M M; Malloy-Diniz, Leandro F; de Miranda, Débora M; Da Silva, Antônio G; Neves, Fernando S; Johnson, Sheri L

2017-01-01

Introduction: Impulsivity is a core characteristic of bipolar disorder and it was observed as elevated in individuals with the disorder and in their relatives. Both impulsivity and history of maltreatment are risk factors for suicide attempts, however, these two key variables may not be independent, given the fact that parental impulsivity and associated social context could increase the risk of child maltreatment. In this study it was examined the association between the impulsivity of relatives and child maltreatment taking into consideration the conjoint and unique effects of these two variables on the risk of suicide attempts among the patients. Materials and Methods: Participants of the study consisted of 117 patients diagnosed with bipolar disorder and 25 first-degree relatives. Linear regression model was conducted to describe associations between facets of impulsivity of relatives and levels of child maltreatment reported by patients. The independent associations of suicide attempt history with the dimensions of impulsivity of the patient and maltreatment were tested by multinomial logistic regression. Results: Impulsivity of relatives and, more specifically, inhibitory control can predict the maltreatment of the patient. Inhibitory control and emotional abuse were related, conjointly, to a greater likelihood of having a history of more than one suicide attempt. Discussion: Considering that the impulsivity of relatives predicts child maltreatment, it is possible that a genetically shared impulsivity is an underlying feature associated with the history of multiple suicide attempts. These findings highlight the importance of considering child maltreatment, impulsivity and suicide attempt history in integrative models.

Integrative Understanding of Familial Impulsivity, Early Adversity and Suicide Risk

PubMed Central

Lima, Isabela M. M.; Malloy-Diniz, Leandro F.; de Miranda, Débora M.; Da Silva, Antônio G.; Neves, Fernando S.; Johnson, Sheri L.

2017-01-01

Introduction: Impulsivity is a core characteristic of bipolar disorder and it was observed as elevated in individuals with the disorder and in their relatives. Both impulsivity and history of maltreatment are risk factors for suicide attempts, however, these two key variables may not be independent, given the fact that parental impulsivity and associated social context could increase the risk of child maltreatment. In this study it was examined the association between the impulsivity of relatives and child maltreatment taking into consideration the conjoint and unique effects of these two variables on the risk of suicide attempts among the patients. Materials and Methods: Participants of the study consisted of 117 patients diagnosed with bipolar disorder and 25 first-degree relatives. Linear regression model was conducted to describe associations between facets of impulsivity of relatives and levels of child maltreatment reported by patients. The independent associations of suicide attempt history with the dimensions of impulsivity of the patient and maltreatment were tested by multinomial logistic regression. Results: Impulsivity of relatives and, more specifically, inhibitory control can predict the maltreatment of the patient. Inhibitory control and emotional abuse were related, conjointly, to a greater likelihood of having a history of more than one suicide attempt. Discussion: Considering that the impulsivity of relatives predicts child maltreatment, it is possible that a genetically shared impulsivity is an underlying feature associated with the history of multiple suicide attempts. These findings highlight the importance of considering child maltreatment, impulsivity and suicide attempt history in integrative models. PMID:29312082

The temporal course and clinical correlates of subjective impulsivity in bipolar disorder as revealed through ecological momentary assessment.

PubMed

Depp, Colin A; Moore, Raeanne C; Dev, Sheena I; Mausbach, Brent T; Eyler, Lisa T; Granholm, Eric L

2016-03-15

Impulsivity is frequently linked with bipolar disorder and is associated with mania and negative outcomes. The temporal dynamics of subjective impulsivity are unclear, in particular whether impulsivity precedes or follows changes in positive or negative affect. A total of 41 outpatients with bipolar disorder (I or II) were provided with mobile devices for 11 weeks and completed twice-daily surveys about affective states and subjective impulsivity. We examined the association between aggregate subjective impulsivity with baseline global cognitive function, suicide risk ratings, and medication adherence, as well as concurrent and lagged associations with momentary positive and negative affect ratings. A total of 2902 ratings were available across study subjects. Higher aggregate mean ratings of impulsivity were associated with worse baseline global cognitive function, prior suicide attempts, and self-reported problems with medication adherence, as well as more severe manic (but not depressive) symptoms. Time-lagged models indicated that greater negative affect, but not positive affect, predicted subsequent increases in subjective impulsivity, which, in turn, predicted diminished positive affect. Other measures of impulsivity with which to validate subjective ratings were unavailable and the sample was restricted to generally clinically stable outpatients. Subjective impulsivity as measured by daily monitoring was associated with worse cognitive function and self-rated medication adherence, and higher suicide risk ratings. Impulsivity may be a maladaptive strategy to regulate negative affect in bipolar disorder. Copyright © 2016. Published by Elsevier B.V.

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

PubMed Central

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

2014-01-01

Behavioral measures of impulsivity are widely used in substance abuse research, yet relatively little attention has been devoted to establishing their psychometric properties, especially their reliability over repeated administration. The current study examined the test-retest reliability of a battery of standardized behavioral impulsivity tasks, including measures of impulsive choice (delay discounting, probability discounting, and the Balloon Analogue Risk Task), impulsive action (the stop signal task, the go/no-go task, and commission errors on the continuous performance task), and inattention (attention lapses on a simple reaction time task and omission errors on the continuous performance task). Healthy adults (n=128) performed the battery on two separate occasions. Reliability estimates for the individual tasks ranged from moderate to high, with Pearson correlations within the specific impulsivity domains as follows: impulsive choice (r = .76 - .89, ps < .001); impulsive action (r = .65 - .73, ps < .001); and inattention (r = .38-.42, ps < .001). Additionally, the influence of day-to-day fluctuations in mood as measured by the Profile of Mood States was assessed in relation to variability in performance on each of the behavioral tasks. Change in performance on the delay discounting task was significantly associated with change in positive mood and arousal. No other behavioral measures were significantly associated with mood. In sum, the current analysis demonstrates that behavioral measures of impulsivity are reliable measures and thus can be confidently used to assess various facets of impulsivity as intermediate phenotypes for drug abuse. PMID:24099351

Dopamine Gene Profiling to Predict Impulse Control and Effects of Dopamine Agonist Ropinirole.

PubMed

MacDonald, Hayley J; Stinear, Cathy M; Ren, April; Coxon, James P; Kao, Justin; Macdonald, Lorraine; Snow, Barry; Cramer, Steven C; Byblow, Winston D

2016-07-01

Dopamine agonists can impair inhibitory control and cause impulse control disorders for those with Parkinson disease (PD), although mechanistically this is not well understood. In this study, we hypothesized that the extent of such drug effects on impulse control is related to specific dopamine gene polymorphisms. This double-blind, placebo-controlled study aimed to examine the effect of single doses of 0.5 and 1.0 mg of the dopamine agonist ropinirole on impulse control in healthy adults of typical age for PD onset. Impulse control was measured by stop signal RT on a response inhibition task and by an index of impulsive decision-making on the Balloon Analogue Risk Task. A dopamine genetic risk score quantified basal dopamine neurotransmission from the influence of five genes: catechol-O-methyltransferase, dopamine transporter, and those encoding receptors D1, D2, and D3. With placebo, impulse control was better for the high versus low genetic risk score groups. Ropinirole modulated impulse control in a manner dependent on genetic risk score. For the lower score group, both doses improved response inhibition (decreased stop signal RT) whereas the lower dose reduced impulsiveness in decision-making. Conversely, the higher score group showed a trend for worsened response inhibition on the lower dose whereas both doses increased impulsiveness in decision-making. The implications of the present findings are that genotyping can be used to predict impulse control and whether it will improve or worsen with the administration of dopamine agonists.

Interacting Mechanisms of Impulsivity in Bipolar Disorder and Antisocial Personality Disorder

PubMed Central

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

2011-01-01

Background Bipolar disorder and antisocial personality disorder (ASPD) overlap in clinical characteristics and behavioral consequences. Impulsivity is prominent in both, but there is little information on how specific mechanisms of impulsivity differentiate, bridge, or underlie the disorders. Methods Subjects, all males, were controls (n=46), bipolar disorder without cluster B personality disorder (n=21), ASPD without bipolar disorder (n=50), and bipolar disorder with ASPD (n=16). Impulsivity measures were the Immediate Memory Task (IMT), a continuous performance test of response inhibition measuring ability to evaluate a stimulus before responding, and the Two Choice Impulsivity Paradigm (TCIP), a choice between smaller-sooner and larger-later reward. Data were analyzed using general linear models analysis. Results Subjects with bipolar disorder had fewer IMT correct detections and slower reaction times than controls. Reaction times were faster with combined diagnoses than in bipolar disorder alone. TCIP responding in either diagnosis alone resembled controls, but was more impulsive in combined disorders. These differences persisted after correction for age and education, which had significant independent effects. In combined ASPD and bipolar disorder, increased reaction speed, impulsive response bias, and reward-delay impulsivity occurred independent of substance-use disorder history. Conclusions Impulsivity was increased in the combined disorders over either disorder alone. Results were consistent with at least partially distinct mechanisms of impulsivity in ASPD and bipolar disorder. Compensatory mechanisms for impulsivity in uncomplicated ASPD or bipolar disorder appear to be compromised or lost when the disorders are combined. PMID:21719028

Impulsivity in Alcohol-Dependent Patients with and without ADHD: The Role of Atomoxetine.

PubMed

Coppola, Maurizio; Mondola, Raffaella

2018-06-07

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by symptoms of hyperactivity, inattention, and impulsivity. As shown in the literature, this disorder is frequently associated with alcohol and drug abuse. Patients affected by ADHD show high levels of impulsivity and sensation seeking. These characteristics can significantly increase the risk of alcohol abuse, which is itself a clinical condition associated with high levels of impulsivity. Clinical studies suggest that atomoxetine is effective and safe in patients affected by both ADHD and alcohol dependence; however, information focused specifically on impulsivity is very limited. In an open-label study, we evaluated the difference in impulsivity level between alcohol-dependent patients with and without a diagnosis of ADHD. Furthermore, we hypothesized that, in patients with ADHD, atomoxetine could reduce the impulsivity trait.

The moderating role of social support on the relationship between impulsivity and suicide risk.

PubMed

Kleiman, Evan M; Riskind, John H; Schaefer, Karen E; Weingarden, Hilary

2012-01-01

Suicide is the second leading cause of death among college students. There has been considerable research into risk factors for suicide, such as impulsivity, but considerably less research on protective factors. The present study examines the role that social support plays in the relationship between impulsivity and suicide risk. Participants were 169 undergraduates who completed self-report measures of impulsivity and social support. Suicide risk was assessed using an interview measure. Social support moderates the relationship between impulsivity and suicide risk, such that those who are highly impulsive are less likely to be at risk for suicide if they also have high levels of social support. Social support can be a useful buffer to suicide risk for at-risk individuals who are highly impulsive.

Impulsive responses to emotion as a transdiagnostic vulnerability to internalizing and externalizing symptoms.

PubMed

Johnson, Sheri L; Carver, Charles S; Joormann, Jutta

2013-09-25

This study explored the hypothesis that impulsive reactions to heightened emotion may reflect a transdiagnostic vulnerability to both externalizing and internalizing symptoms. A sample of undergraduates completed self-report measures of aggression, borderline personality disorder symptoms, anxiety symptoms, and alcohol problems, and a subset completed interviews that assessed suicidality. All participants also completed self-report measures relating to impulsivity. We predicted that emotion-reactive impulsivity, but not other aspects of impulsivity, would be related to the set of psychopathology symptoms. Multiple regression analyses found that emotion-reactive impulsivity was uniquely related to each of the psychopathology scales, whereas non-emotion-relevant impulsivity was uniquely related only to alcohol problems. Discussion focuses on limitations and clinical implications. © 2013 Elsevier B.V. All rights reserved.

(Dis)similarity in Impulsivity and Marital Satisfaction: A Comparison of Volatility, Compatibility, and Incompatibility Hypotheses

PubMed Central

Derrick, Jaye L.; Houston, Rebecca J.; Quigley, Brian M.; Testa, Maria; Kubiak, Audrey; Levitt, Ash; Homish, Gregory G.; Leonard, Kenneth E.

2016-01-01

Impulsivity is negatively associated with relationship satisfaction, but whether relationship functioning is harmed or helped when both partners are high in impulsivity is unclear. The influence of impulsivity might be exacerbated (the Volatility Hypothesis) or reversed (the Compatibility Hypothesis). Alternatively, discrepancies in impulsivity might be particularly problematic (the Incompatibility Hypothesis). Behavioral and self-report measures of impulsivity were collected from a community sample of couples. Mixed effect polynomial regressions with response surface analysis provide evidence in favor of both the Compatibility Hypothesis and the Incompatibility Hypothesis, but not the Volatility Hypothesis. Mediation analyses suggest results for satisfaction are driven by perceptions of the partner's negative behavior and responsiveness. Implications for the study of both impulsivity and relationship functioning are discussed. PMID:26949275

Impulsivity and sexual assault in college men.

PubMed

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

2013-01-01

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).

Attentional and motor impulsivity interactively predict 'food addiction' in obese individuals.

PubMed

Meule, Adrian; de Zwaan, Martina; Müller, Astrid

2017-01-01

Impulsivity is a multifaceted construct and constitutes a common risk factor for a range of behaviors associated with poor self-control (e.g., substance use or binge eating). The short form of the Barratt Impulsiveness Scale (BIS-15) measures impulsive behaviors related to attentional (inability to focus attention or concentrate), motor (acting without thinking), and non-planning (lack of future orientation or forethought) impulsivity. Eating-related measures appear to be particularly related to attentional and motor impulsivity and recent findings suggest that interactive effects between these two facets may play a role in eating- and weight-regulation. One-hundred thirty-three obese individuals presenting for bariatric surgery (77.4% female) completed the BIS-15 and the Yale Food Addiction Scale (YFAS) 2.0, which measures addiction-like eating based on the eleven symptoms of substance use disorder outlined in the fifth version of the Diagnostic and Statistical Manual of Mental Disorders. Sixty-three participants (47.4%) were classified as being 'food addicted'. Scores on attentional and motor impulsivity interactively predicted 'food addiction' status: higher attentional impulsivity was associated with a higher likelihood of receiving a YFAS 2.0 diagnosis only at high (+1 SD), but not at low (-1 SD) levels of motor impulsivity. Results support previous findings showing that non-planning impulsivity does not appear to play a role in eating-related self-regulation. Furthermore, this is the first study that shows interactive effects between different impulsivity facets when predicting 'food addiction' in obese individuals. Self-regulatory failure in eating-regulation (e.g., addiction-like overeating) may particularly emerge when both attentional and motor impulsivity levels are elevated. Copyright © 2016 Elsevier Inc. All rights reserved.

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

PubMed Central

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

2014-01-01

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, p < 0.01), as those who had higher educational attainment also reported lower rates of trait impulsivity. In addition, those over the age of 30 demonstrated lower impulsivity in decision-making (as measured by delay discounting) than those under 30 (t = 2.21, 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

Attention switching after dietary brain 5-HT challenge in high impulsive subjects.

PubMed

Markus, C Rob; Jonkman, Lisa M

2007-09-01

High levels of impulsivity have adverse effects on performance in cognitive tasks, particularLy in those tasks that require high attention investment. Furthermore, both animal and human research has indicated that reduced brain serotonin (5-HT) function is associated with increases in impulsive behaviour or decreased inhibition ability, but the effects of 5-HT challenge have not yet been investigated in subjects vulnerable to impulsivity. The present study aimed to investigate whether subjects with high trait impulsivity perform worse than low impulsive subjects in a task switching paradigm in which they have to rapidly shift their attention between two response rules, and to investigate the influence of a 5-HT enhancing diet. Healthy subjects with high ( n = 19) and low (n = 18) trait impulsivity scores participated in a double-blind placebo-controlled study. All subjects performed the attention switch task in the morning following breakfast containing either tryptophan-rich alpha-lactalbumin (4.8 g/100 g TRP) or placebo protein (1.4 g/100 g TRP). Whereas there were no baseline differences between high and low impulsive subjects in task switching abilities, high impulsive subjects made significantly more switch errors and responded slower after dietary 5-HT stimulation, whereas no dietary effects were found on task switching performance in low-impulsive subjects. The deterioration in task switching performance induced by the 5-HT enhancing diet in high impulsive subjects was suggested to be established by general arousal/attention-reducing effects of 5-HT, which might have a larger impact in high impulsive subjects due to either different brain circuitry involved in task switching in this group or lower baseline arousal levels.

Impulsive behaviour in rats induced by intracortical DOI infusions is antagonized by co-administration of an mGlu2/3 receptor agonist.

PubMed

Wischhof, Lena; Hollensteiner, Karl J; Koch, Michael

2011-12-01

The orbitofrontal cortex (OFC) and the medial prefrontal cortex (mPFC) modulate impulsive behaviours. Serotonin [5-hydroxytryptamine (5-HT)] 2A receptors have also been implicated in impulsivity and govern antagonistic interactions with metabotropic glutamate (mGlu)2/3 receptors. This study examined the interactions between 5-HT2A and mGlu2/3 receptors in the OFC and mPFC with relevance to impulsive choice and impulsive action. Impulsive choice was assessed in Lister Hooded rats, trained in a delay-discounting T-maze task, after bilateral intra-OFC infusions of the 5-HT2A/C receptor agonist DOI [(+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropan hydrochloride; 5 μg/0.5 μl] and the mGlu2/3 receptor agonist LY379268 (1 μg/0.5 μl). Impulsive action was assessed in a second group of rats trained in a five-choice serial reaction time task (5-CSRTT) and receiving bilateral intra-mPFC infusions of DOI (5 μg/0.5 μl) and LY379268 (1 μg/0.5 μl). Intra-OFC DOI increased impulsive choice, which was not seen when DOI was co-administered with LY379268. LY379268 itself had no effect on choice behaviour. Intra-mPFC DOI caused impulsive over-responding in the 5-CSRTT that was attenuated when DOI and LY379268 were co-injected. Local mPFC-infusions of LY379268 had no effect on 5-CSRTT performance. This study suggests a differential involvement of OFC and mPFC 5-HT2A receptors in impulsive choice and impulsive action. Moreover, compounds acting at mGlu2/3 receptors might have the potential to improve impulsivity-related impairments.

Neurocognitive and psychiatric dimensions of hot, but not cool, impulsivity predict HIV sexual risk behaviors among drug users in protracted abstinence.

PubMed

Wilson, Michael J; Vassileva, Jasmin

2016-03-01

Impulsivity is an important risk factor for HIV risky drug and sexual behaviors. Research identifies hot (i.e. affectively-mediated, reward-based) and cool (motoric, attentional, independent of context) neurocognitive and psychiatric dimensions of impulsivity, though the impact of specific drugs of abuse on these varieties of impulsivity remains an open question. The present study examined the associations of neurocognitive and psychiatric varieties of hot and cool impulsivity with measures of lifetime and recent sexual risk behaviors among users of different classes of drugs. The study sample was comprised of drug users in protracted (> 1 year) abstinence: heroin mono-dependent (n = 61), amphetamine mono-dependent (n = 44), and polysubstance dependent (n = 73). Hot impulsivity was operationalized via neurocognitive tasks of reward-based decision-making and symptoms of psychopathy. Cool impulsivity was operationalized via neurocognitive tasks of response inhibition and symptoms of attention deficit/hyperactivity disorder (ADHD). Hot impulsivity was associated with sexual risk behaviors among heroin and amphetamine users in protracted abstinence, whereas cool impulsivity was not associated with sexual risk behaviors among any drug-using group. Neurocognitive hot impulsivity was associated with recent (past 30-day) sexual risk behaviors, whereas psychopathy was associated with sexual risk behaviors during more remote time-periods (past 6 month and lifetime) and mediated the association between heroin dependence and past 6-month sexual risk behaviors. Assessments and interventions aimed at reducing sexual risk behaviors among drug users should focus on hot neurocognitive and psychiatric dimensions of impulsivity, such as decision-making and psychopathy. Cool dimensions of impulsivity such as response inhibition and ADHD were not related to sexual risk behaviors among drug users in protracted abstinence.

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

PubMed

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

2014-11-01

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

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

PubMed Central

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

2015-01-01

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

Muscle-Specific Effective Mechanical Advantage and Joint Impulse in Weightlifting.

PubMed

Kipp, Kristof; Harris, Chad

2017-07-01

Kipp, K, and Harris, C. Muscle-specific effective mechanical advantage and joint impulse in weightlifting. J Strength Cond Res 31(7): 1905-1910, 2017-Lifting greater loads during weightlifting exercises may theoretically be achieved through increasing the magnitudes of net joint impulses or manipulating the joints' effective mechanical advantage (EMA). The purpose of this study was to investigate muscle-specific EMA and joint impulse as well as impulse-momentum characteristics of the lifter-barbell system across a range of external loads during the execution of the clean. Collegiate-level weightlifters performed submaximal cleans at 65, 75, and 85% of their 1-repetition maximum (1-RM), whereas data from a motion analysis system and a force plate were used to calculate lifter-barbell system impulse and velocity, as well as net extensor impulse generated at the hip, knee, and ankle joints and the EMA of the gluteus maximus, hamstrings, quadriceps, and triceps surae muscles. The results indicated that the lifter-barbell system impulse did not change as load increased, whereas the velocity of the lifter-barbell system decreased with greater load. In addition, the net extensor impulse at all joints increased as load increased. The EMA of all muscles did not, however, change as load increased. The load-dependent effects on the impulse-velocity characteristics of the lifter-barbell system may reflect musculoskeletal force-velocity behaviors, and may further indicate that the weightlifting performance is limited by the magnitude of ground reaction force impulse. In turn, the load-dependent effects observed at the joint level indicated that lifting greater loads were due to greater net extensor impulses generated at the joints of the lower extremity and not greater EMAs of the respective extensor muscles. In combination, these results suggest that lifting greater external loads during the clean is due to the ability to generate large extensor joint impulses, rather than manipulate EMA.

Impulsivity facets’ predictive relations with DSM-5 PTSD symptom clusters

PubMed Central

Roley, Michelle E.; Contractor, Ateka A.; Weiss, Nicole H.; Armour, Cherie; Elhai, Jon D.

2017-01-01

Objective Posttraumatic Stress Disorder (PTSD) has a well-established theoretical and empirical relation with impulsivity. Prior research has not used a multidimensional approach for measuring both PTSD and impulsivity constructs when assessing their relationship. Method The current study assessed the unique relationship of impulsivity facets on PTSD symptom clusters among a non-clinical sample of 412 trauma-exposed adults. Results Linear regression analyses revealed that impulsivity facets best accounted for PTSD’s arousal symptoms. The negative urgency facet of impulsivity was most predictive, as it was associated with all of PTSD’s symptom clusters. Sensation seeking did not predict PTSD’s intrusion symptoms, but did predict the other symptom clusters of PTSD. Lack of perseverance only predicted intrusion symptoms, while lack of premeditation only predicted PTSD’s mood/cognition symptoms. Conclusions Results extend theoretical and empirical research on the impulsivity-PTSD relationship, suggesting that impulsivity facets may serve as both risk and protective factors for PTSD symptoms. PMID:27243571

Impulsivity facets' predictive relations with DSM-5 PTSD symptom clusters.

PubMed

Roley, Michelle E; Contractor, Ateka A; Weiss, Nicole H; Armour, Cherie; Elhai, Jon D

2017-01-01

Posttraumatic stress disorder (PTSD) has a well-established theoretical and empirical relation with impulsivity. Prior research has not used a multidimensional approach for measuring both PTSD and impulsivity constructs when assessing their relationship. The current study assessed the unique relationship of impulsivity facets on PTSD symptom clusters among a nonclinical sample of 412 trauma-exposed adults. Linear regression analyses revealed that impulsivity facets best accounted for PTSD's arousal symptoms. The negative urgency facet of impulsivity was most predictive, because it was associated with all of PTSD's symptom clusters. Sensation seeking did not predict PTSD's intrusion symptoms, but did predict the other symptom clusters of PTSD. Lack of perseverance only predicted intrusion symptoms, while lack of premeditation only predicted PTSD's mood/cognition symptoms. Results extend theoretical and empirical research on the impulsivity-PTSD relationship, suggesting that impulsivity facets may serve as both risk and protective factors for PTSD symptoms. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Aggressive Behavior Among Military Veterans in Substance Use Disorder Treatment: The Roles of Posttraumatic Stress and Impulsivity

PubMed Central

Heinz, Adrienne J.; Makin-Byrd, Kerry; Blonigen, Daniel M.; Reilly, Patrick; Timko, Christine

2015-01-01

This study examined posttraumatic stress disorder (PTSD) symptom severity and impulsivity as predictors of aggressive behavior among 133 male military Veterans entering substance abuse treatment who endorsed difficulty controlling anger in the past year. At treatment intake, participants completed measures assessing PTSD symptom severity, impulsivity and aggressive behavior. Perpetration of aggressive behavior was reassessed four months later. Results from multivariate models indicated that PTSD symptom severity and impulsivity explained unique variance in aggressive behavior at intake but not follow-up. Mediation models indicated that the association between PTSD symptom severity and aggressive behavior was accounted for by impulsivity. The identification of impulsivity as a key mediator between trauma symptoms and aggressive behavior has significant clinical and research implications. Based on these findings, clinicians are encouraged to consider a standard assessment of impulsivity and the selection of interventions that target impulsivity as a trans-diagnostic process among at-risk client populations. PMID:25468005

[Relationship among inattentive and hyperactive-impulsive behavior, aggression, and depression in Japanese elementary and junior high school students].

PubMed

Noda, Wataru; Okada, Ryo; Tani, Iori; Ohnishi, Masafumi; Naoto, Mochizuki; Nakajima, Syunji; Tsujii, Masatsugu

2013-06-01

The present study examines the relationship among inattentive, and hyperactive-impulsive behavior, aggression, and depression in elementary school and junior high school students. The participants were 3,885 children and their teachers and caregivers. Children's inattentive and hyperactive-impulsive behavior was rated by their teachers and caregivers (ADHD-RS). Children rated aggression (HAQ-C) and depression (DSRS-C) themselves. Inattentive and hyperactive-impulsive behavior rated by teachers and caregivers were positively related to aggression and depression. Inattention predicted higher levels of aggression and depression. Inattentive and hyperactive-impulsive behavior as rated by teachers was more highly related to depression than those behaviors as rated by caregivers. The relationships among inattentive, and hyperactive-impulsive behavior, aggression, and depression were almost the same for both elementary school and junior high school students. This study suggests the importance of assessing inattentive and hyperactive-impulsive behavior from multiple views to examine the relationship between inattentive and hyperactive-impulsive behavior and mental health problems.

Impulsivity in remitted depression: a meta-analytical review.

PubMed

Saddichha, Sahoo; Schuetz, Christian

2014-06-01

Depressive disorder and suicide have been associated with impulsivity in several studies. This paper aimed to review measures of trait impulsivity in remitted depressive disorder. We used keywords "impulsivity and depression"; "impulsivity and depressive disorder" to narrow down our search on Medline, EMBASE and Psychinfo to include those studies that had reported impulsivity scores using validated and reliable assessment measures in remitted depressive disorder. We searched all English language studies from 1990 to December 2012 with 9 reports meeting the inclusion criteria for depression, which were then reviewed by the two reviewers independently. We generated weighted mean differences (WMDs) for depression from the pooled data using RevManager 5.1 from Cochrane analysis. The Barratt Impulsivity Scale (BIS) 11 was the instrument commonly used in depression. 9 studies met inclusion criteria in depression, which yielded a WMD of 10.12 on BIS 11 total scores. There is a strong association of impulsivity and depression, which persists even in remission. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparison among various methods of assessment of impulsiveness.

PubMed

Carrillo-de-la-Peña, M T; Otero, J M; Romero, E

1993-10-01

The current confused status of the research on impulsivity may be attributed to the lack of precise definitions, the reliance of most operationalizations on a single index, and inconsistency among different measures of the construct. Empirical measurements of impulsivity by self-reports, rating scales, or performance tasks suggest that the instruments employed measure aspects that have very little in common, a finding that throws serious doubts on the validity of the construct and implies a need for further research. To clarify this topic, we applied four different measures of impulsivity to 46 7th-grade (12 to 13 years old) schoolchildren. The children were rated by their teachers on an impulsivity behavior scale and were administered Kagan's Matching Familiar Figures Test, Version MFF-20, and two self-report forms, the Eysenck Impulsiveness Questionnaire, and the Barratt Impulsiveness Scale. Although the results confirmed the lack of convergence among these measures, high latencies on matching were associated with the cognitive aspect of the self-report scales. Treating impulsivity as a multidimensional construct is discussed.

Periodicity and stability for variable-time impulsive neural networks.

PubMed

Li, Hongfei; Li, Chuandong; Huang, Tingwen

2017-10-01

The paper considers a general neural networks model with variable-time impulses. It is shown that each solution of the system intersects with every discontinuous surface exactly once via several new well-proposed assumptions. Moreover, based on the comparison principle, this paper shows that neural networks with variable-time impulse can be reduced to the corresponding neural network with fixed-time impulses under well-selected conditions. Meanwhile, the fixed-time impulsive systems can be regarded as the comparison system of the variable-time impulsive neural networks. Furthermore, a series of sufficient criteria are derived to ensure the existence and global exponential stability of periodic solution of variable-time impulsive neural networks, and to illustrate the same stability properties between variable-time impulsive neural networks and the fixed-time ones. The new criteria are established by applying Schaefer's fixed point theorem combined with the use of inequality technique. Finally, a numerical example is presented to show the effectiveness of the proposed results. Copyright © 2017 Elsevier Ltd. All rights reserved.

The overlooked relationship between motivational abilities and posttraumatic stress: a review

PubMed Central

Simmen-Janevska, Keti; Brandstätter, Veronika; Maercker, Andreas

2012-01-01

How does traumatic stress change the ability to motivate oneself to achieve certain goals? How do motivational abilities influence the development and course of trauma sequelae? Few studies have focused on motivational constructs within posttraumatic stress research. From a trauma research perspective, it can be hypothesized that traumatic stress may contribute to motivational dysfunction. The main goal of the present article is to fill this gap in research by reviewing and discussing the existing trauma literature in terms of motivation-related concepts, such as self-efficacy, locus of control, self-esteem, and self-control/impulsivity. Fifty-four studies were reviewed, 10 of which were longitudinal studies. Approximately 20% of the reviews assessed whether motivational concepts predict posttraumatic stress, whereas only 8% examined the reverse relationship. With the exception of a few studies, motivational constructs seem to predict posttraumatic stress over the life span. The strongest relationships were reported for self-efficacy, followed by locus of control and self-esteem and, lastly, impulsivity/self-control. Overall, the findings of this review indicate that there is a lack of research investigating motivational factors as outcome variables following traumatic experiences. Furthermore, the need for longitudinal studies and studies with older adults is noted. PMID:23125909

A 128-Tap Highly Tunable CMOS IF Finite Impulse Response Filter for Pulsed Radar Applications

DOE PAGES

Mincey, John Stephen; Su, Eric C.; Silva-Martinez, Jose; ...

2018-02-28

A configurable-bandwidth (BW) filter is presented in this paper for pulsed radar applications. Also, to eliminate dispersion effects in the received waveform, a finite impulse response (FIR) topology is proposed, which has a measured standard deviation of an in-band group delay of 11 ns that is primarily dominated by the inherent, fully predictable delay introduced by the sample-and-hold. The filter operates at an IF of 20 MHz, and is tunable in BW from 1.5 to 15 MHz, which makes it optimal to be used with varying pulse widths in the radar. Employing a total of 128 taps, the FIR filtermore » provides greater than 50-dB sharp attenuation in the stopband in order to minimize all out-of-band noise in the low signal-to-noise received radar signal. Fabricated in a 0.18-μm silicon on insulator CMOS process, the proposed filter consumes approximately 3.5 mW/tap with a 1.8-V supply. Finally, a 20-MHz two-tone measurement with 200-kHz tone separation shows IIP3 greater than 8.5 dBm.« less

Dynamic tunable notch filters for the Antarctic Impulsive Transient Antenna (ANITA)

NASA Astrophysics Data System (ADS)

Allison, P.; Banerjee, O.; Beatty, J. J.; Connolly, A.; Deaconu, C.; Gordon, J.; Gorham, P. W.; Kovacevich, M.; Miki, C.; Oberla, E.; Roberts, J.; Rotter, B.; Stafford, S.; Tatem, K.; Batten, L.; Belov, K.; Besson, D. Z.; Binns, W. R.; Bugaev, V.; Cao, P.; Chen, C.; Chen, P.; Chen, Y.; Clem, J. M.; Cremonesi, L.; Dailey, B.; Dowkontt, P. F.; Hsu, S.; Huang, J.; Hupe, R.; Israel, M. H.; Kowalski, J.; Lam, J.; Learned, J. G.; Liewer, K. M.; Liu, T. C.; Ludwig, A. B.; Matsuno, S.; Mulrey, K.; Nam, J.; Nichol, R. J.; Novikov, A.; Prohira, S.; Rauch, B. F.; Ripa, J.; Romero-Wolf, A.; Russell, J.; Saltzberg, D.; Seckel, D.; Shiao, J.; Stockham, J.; Stockham, M.; Strutt, B.; Varner, G. S.; Vieregg, A. G.; Wang, S.; Wissel, S. A.; Wu, F.; Young, R.

2018-06-01

The Antarctic Impulsive Transient Antenna (ANITA) is a NASA long-duration balloon experiment with the primary goal of detecting ultra-high-energy (> 1018eV) neutrinos via the Askaryan Effect. The fourth ANITA mission, ANITA-IV, recently flew from Dec 2 to Dec 29, 2016. For the first time, the Tunable Universal Filter Frontend (TUFF) boards were deployed for mitigation of narrow-band, anthropogenic noise with tunable, switchable notch filters. The TUFF boards also performed second-stage amplification by approximately 45 dB to boost the ∼ μV-level radio frequency (RF) signals to ∼ mV-level for digitization, and supplied power via bias tees to the first-stage, antenna-mounted amplifiers. The other major change in signal processing in ANITA-IV is the resurrection of the 90 ° hybrids deployed previously in ANITA-I, in the trigger system, although in this paper we focus on the TUFF boards. During the ANITA-IV mission, the TUFF boards were successfully operated throughout the flight. They contributed to a factor of 2.8 higher total instrument livetime on average in ANITA-IV compared to ANITA-III due to reduction of narrow-band, anthropogenic noise before a trigger decision is made.

A 128-Tap Highly Tunable CMOS IF Finite Impulse Response Filter for Pulsed Radar Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mincey, John Stephen; Su, Eric C.; Silva-Martinez, Jose

A configurable-bandwidth (BW) filter is presented in this paper for pulsed radar applications. Also, to eliminate dispersion effects in the received waveform, a finite impulse response (FIR) topology is proposed, which has a measured standard deviation of an in-band group delay of 11 ns that is primarily dominated by the inherent, fully predictable delay introduced by the sample-and-hold. The filter operates at an IF of 20 MHz, and is tunable in BW from 1.5 to 15 MHz, which makes it optimal to be used with varying pulse widths in the radar. Employing a total of 128 taps, the FIR filtermore » provides greater than 50-dB sharp attenuation in the stopband in order to minimize all out-of-band noise in the low signal-to-noise received radar signal. Fabricated in a 0.18-μm silicon on insulator CMOS process, the proposed filter consumes approximately 3.5 mW/tap with a 1.8-V supply. Finally, a 20-MHz two-tone measurement with 200-kHz tone separation shows IIP3 greater than 8.5 dBm.« less

Sex differences in dimensions of impulsivity in a non-clinical sample.

PubMed

Lage, Guilherme Menezes; Albuquerque, Maicon Rodrigues; Fuentes, Daniel; Corrêa, Humberto; Malloy-Diniz, Leandro Fernandes

2013-10-01

Impulsivity has been more closely associated with men than with women because men are more often involved in illegal behaviors. The few studies that have investigated sex differences in impulsivity have used self-report questionnaires and have obtained contradictory results. Two computerized behavioral tests were administered to 125 healthy undergraduate students (75 women, M age 23.8 yr.; 50 men, M age 25.0 yr.). Men exhibited higher scores on motor impulsivity, but there were no significant differences between men and women on attentional and non-planning impulsivity scores. These findings are discussed in terms of the relationship between impulsivity and low- and high-order control.

Differences in Trait Impulsivity Indicate Diversification of Dog Breeds into Working and Show Lines.

PubMed

Fadel, Fernanda Ruiz; Driscoll, Patricia; Pilot, Malgorzata; Wright, Hannah; Zulch, Helen; Mills, Daniel

2016-03-10

Impulsiveness describes the inability to inhibit behaviour in the presence of salient cues. Trait-level impulsivity exists on a continuum and individual differences can be adaptive in different contexts. While breed related differences in behavioural tendency in the domestic dog (Canis familiaris) are well established, the phenomenon within lines of a breed which have been selected more recently is not well studied, although it may challenge the popular notion of breed-typical behaviour. We describe differences in impulsivity between and within two dog breeds with working and show lines selected for different levels of impulsivity: Border Collies (herding work) and Labrador Retrievers (gun work). Recent show line selection might have lessened differences in impulsivity between breeds. We tested this hypothesis on a dataset of 1161 individuals assessed using a validated psychometric tool (Dog Impulsivity Assessment Scale--DIAS). Collies were more impulsive on average, consistent with the original purpose of breed selection. Regarding line, working Collies differed from working Labradors, but show lines from the two breeds were not significantly different. Altered or relaxed artificial selection for behavioural traits when appearance rather than behaviour become the primary focus for breeders may reduce average differences in impulsivity between breeds in show lines.

I can't wait: Methods for measuring and moderating individual differences in impulsive choice.

PubMed

Peterson, Jennifer R; Hill, Catherine C; Marshall, Andrew T; Stuebing, Sarah L; Kirkpatrick, Kimberly

2015-01-01

Impulsive choice behavior occurs when individuals make choices without regard for future consequences. This behavior is often maladaptive and is a common symptom in many disorders, including drug abuse, compulsive gambling, and obesity. Several proposed mechanisms may influence impulsive choice behavior. These mechanisms provide a variety of pathways that may provide the basis for individual differences that are often evident when measuring choice behavior. This review provides an overview of these different pathways to impulsive choice, and the behavioral intervention strategies being developed to moderate impulsive choice. Because of the compelling link between impulsive choice behavior and the near-epidemic pervasiveness of obesity in the United States, we focus on the relationship between impulsive choice behavior and obesity as a test case for application of the multiple pathways approach. Choosing immediate gratification over healthier long term food choices is a contributing factor to the obesity crisis. Behavioral interventions can lead to more self controlled choices in a rat pre-clinical model, suggesting a possible gateway for translation to human populations. Designing and implementing effective impulsive choice interventions is crucial to improving the overall health and well-being of impulsive individuals.

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

PubMed Central

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

2014-01-01

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

Impulsivity in abstinent early- and late-onset alcoholics: differences in self-report measures and a discounting task.

PubMed

Dom, G; D'haene, P; Hulstijn, W; Sabbe, B

2006-01-01

To test the hypothesis that early-onset alcoholics (EOAs) can be differentiated from late-onset alcoholics (LOAs) by more severe substance-related problems and higher levels of impulsivity and aggression. A cross-sectional patient survey with a community comparison group. The European Addiction Severity Index was used to assess substance-related problems and the Barratt Impulsiveness Scale, the Dutch version of the Zuckermann Sensation Seeking Scale and the Buss-Durkee Hostility Inventory were used to assess impulsive and aggressive traits. Impulsive decision making was assessed using a delay discounting task (DDT) with hypothetical monetary rewards. Participants were EOAs (n = 42) and LOAs (n = 46) recruited from an addiction treatment centre and an unmatched, non-substance-abusing comparison group (n = 54). Findings The EOAs had higher levels of impulsive decision making than both the LOAs and the comparison group. The EOAs had higher scores than the LOAs on measures of impulsiveness, aggressiveness and the severity of substance-related problems. This study provides evidence that EOAs are more impulsive and aggressive than LOAs. Further identification of alcoholism subtypes based on dimensions of impulsivity should be considered in the light of their relationship with pharmacological and behavioural treatment interventions.

Angular Impulse and Balance Regulation During the Golf Swing.

PubMed

Peterson, Travis J; Wilcox, Rand R; McNitt-Gray, Jill L

2016-08-01

Our aim was to determine how skilled players regulate linear and angular impulse while maintaining balance during the golf swing. Eleven highly-skilled golf players performed swings with a 6-iron and driver. Components contributing to linear and angular impulse generated by the rear and target legs (resultant horizontal reaction force [RFh], RFh-angle, and moment arm) were quantified and compared across the group and within a player (α = .05). Net angular impulse generated by both the rear and target legs was greater for the driver than the 6-iron. Mechanisms used to regulate angular impulse generation between clubs varied across players and required coordination between the legs. Increases in net angular impulse with a driver involved increases in target leg RFh. Rear leg RFh-angle was maintained between clubs whereas target leg RFh became more aligned with the target line. Net linear impulse perpendicular to the target line remained near zero, preserving balance, while net linear impulse along the target line decreased in magnitude. These results indicate that the net angular impulse was regulated between clubs by coordinating force generation of the rear and target legs while sustaining balance throughout the task.

Impulsivity in bipolar disorders in a Tunisian sample.

PubMed

Feki, Ines; Moalla, Mariem; Baati, Imen; Trigui, Dorsaf; Sellami, Rim; Masmoudi, Jaweher

2016-08-01

Impulsivity as a trait characteristic is increased in bipolar disorder and may be a core factor of the illness. The objectives of our work are to evaluate the level of impulsivity among patients with bipolar disorder and to study its relation with mood state, alcohol misuse, suicide attempts and other socio-demographic and clinical factors. We measured impulsivity in 60 subjects with bipolar disorder in relationship to socio-demographic and clinical variables. The subjects completed Data included socio-demographic details and clinical variables, the Barratt Impulsiveness Scale (BIS-11) in an Arabic version to assess impulsivity, The Mini International Neuropsychiatric Interview "MINI" version 05 to screen for alcohol abuse or dependence and mood graphic rate scale (MGRS) to evaluate mood state. Our results show that the mean score of BIS-11 was 71.5. Fifty-five per cent of the patients had a high level of impulsiveness. No differences were found relating to mood state. Impulsivity was related to Male gender, lower educational level, early age of onset, smoking, alcohol and drug misuse and prior suicide attempts. The treatment of patients with BD should consider to reduce impulsivity to improve morbidity. Copyright © 2016 Elsevier B.V. All rights reserved.

Psychometric properties of the Barratt Impulsiveness Scale in patients with gambling disorders, hypersexuality, and methamphetamine dependence.

PubMed

Reid, Rory C; Cyders, Melissa A; Moghaddam, Jacquelene F; Fong, Timothy W

2014-11-01

Although the Barratt Impulsiveness Scale (BIS; Patton, Stanford, & Barratt, 1995) is a widely-used self-report measure of impulsivity, there have been numerous questions about the invariance of the factor structure across clinical populations (Haden & Shiva, 2008, 2009; Ireland & Archer, 2008). The goal of this article is to examine the factor structure of the BIS among a sample consisting of three populations exhibiting addictive behaviors and impulsivity: pathological gamblers, hypersexual patients, and individuals seeking treatment for methamphetamine dependence to determine if modification to the existing factors might improve the psychometric properties of the BIS. The current study found that the factor structure of the BIS does not replicate in this sample and instead produces a 12-item three-factor solution consisting of motor-impulsiveness (5 items), non-planning impulsiveness (3 items), and immediacy impulsiveness (4 items). The clinical utility of the BIS in this population is questionable. The authors suggest future studies to investigate comparisons with this modified version of the BIS and other impulsivity scales such as the UPPS-P Impulsive Behavior Scale in clinical populations when assessing disposition toward rash action. Copyright © 2013. Published by Elsevier Ltd.

Gender differences in the relationship between impulsivity and disordered eating behaviors and attitudes.

PubMed

Lundahl, Alyssa; Wahlstrom, Laura C; Christ, Christa C; Stoltenberg, Scott F

2015-08-01

We investigated relationships among gender, impulsivity and disordered eating in healthy college students. Participants (N=1223) were healthy, undergraduate men (28.5%) and women (71.5%), who completed the Barratt Impulsiveness Scale - Version 11 (BIS-11) and a four-factor version of the Eating Attitudes Test (EAT-16). As predicted, mean scores on all four EAT-16 factors were significantly higher for women than for men. Attentional impulsivity was related to poorer self-perception of body shape, more dieting, and a greater preoccupation with food for the sample as a whole. Moreover, motor impulsivity was related to poorer self-perceptions of body shape and a greater preoccupation with food. However, no gender differences emerged in the relationship between impulsivity and disordered eating attitudes. This study elucidates the role of impulsivity in disordered eating behaviors among non-clinical college students. For both women and men, attentional and motor impulsivity were related to disordered eating attitudes and behaviors. Overall, these findings suggest that different facets of impulsivity are related to disordered eating attitudes and behaviors in a non-clinical college population. Copyright © 2015 Elsevier Ltd. All rights reserved.

I can't wait: Methods for measuring and moderating individual differences in impulsive choice

PubMed Central

Peterson, Jennifer R.; Hill, Catherine C.; Marshall, Andrew T.; Stuebing, Sarah L.; Kirkpatrick, Kimberly

2016-01-01

Impulsive choice behavior occurs when individuals make choices without regard for future consequences. This behavior is often maladaptive and is a common symptom in many disorders, including drug abuse, compulsive gambling, and obesity. Several proposed mechanisms may influence impulsive choice behavior. These mechanisms provide a variety of pathways that may provide the basis for individual differences that are often evident when measuring choice behavior. This review provides an overview of these different pathways to impulsive choice, and the behavioral intervention strategies being developed to moderate impulsive choice. Because of the compelling link between impulsive choice behavior and the near-epidemic pervasiveness of obesity in the United States, we focus on the relationship between impulsive choice behavior and obesity as a test case for application of the multiple pathways approach. Choosing immediate gratification over healthier long term food choices is a contributing factor to the obesity crisis. Behavioral interventions can lead to more self controlled choices in a rat pre-clinical model, suggesting a possible gateway for translation to human populations. Designing and implementing effective impulsive choice interventions is crucial to improving the overall health and well-being of impulsive individuals. PMID:27695664

Modification of Impulse Generation During Pirouette Turns With Increased Rotational Demands.

PubMed

Zaferiou, Antonia M; Wilcox, Rand R; McNitt-Gray, Jill L

2016-10-01

This study determined how dancers regulated angular and linear impulse during the initiation of pirouettes of increased rotation. Skilled dancers (n = 11) performed single and double pirouette turns with each foot supported by a force plate. Linear and angular impulses generated by each leg were quantified and compared between turn types using probability-based statistical methods. As rotational demands increased, dancers increased the net angular impulse generated. The contribution of each leg to net angular impulse in both single and double pirouettes was influenced by stance configuration strategies. Dancers who generated more angular impulse with the push leg than with the turn leg initiated the turn with the center of mass positioned closer to the turn leg than did other dancers. As rotational demands increased, dancers tended to increase the horizontal reaction force magnitude at one or both feet; however, they used subject-specific mechanisms. By coordinating the generation of reaction forces between legs, changes in net horizontal impulse remained minimal, despite impulse regulation at each leg used to achieve more rotations. Knowledge gained regarding how an individual coordinates the generation of linear and angular impulse between both legs as rotational demand increased can help design tools to improve that individual's performance.

Impulsiveness and venturesomeness in German smokers.

PubMed

Bernow, Nina; Kruck, Bernadette; Pfeifer, Philippe; Lieb, Klaus; Tüscher, Oliver; Fehr, Christoph

2011-08-01

Cigarette smoking is a behavior, which is influenced by genetic, demographic, and psychological factors. A large body of research has examined the association of cigarette smoking variables with individual differences in personality traits. The aim of the current study was to replicate the findings of higher self-reported impulsivity in smokers compared with never-smokers in a German sample using Eysenck´s construct of impulsivity. Furthermore, it was intended to further the knowledge about associations between different self-reported impulsivity components and different smoking variables. We used the Impulsiveness-Venturesomeness-Empathy questionnaire (I7) to measure self-reported impulsiveness and venturesomeness and the Temperament and Character Inventory (TCI) to measure novelty seeking (NS) in a sample of 82 nicotine-dependent smokers and 119 never-smokers. Smokers scored higher on impulsiveness, venturesomeness, and NS than never-smokers independent of age, gender, and years of education. We found a significant association between venturesomeness, impulsiveness and smoking status in daily smokers. In summary, this study provides evidence that impulsiveness and venturesomeness as well as the novelty-seeking subscale extravagance are significantly associated with smoking status in a German sample of female and male smokers compared with never-smokers.

A multidimensional approach of impulsivity in adult attention deficit hyperactivity disorder.

PubMed

Lopez, Régis; Dauvilliers, Yves; Jaussent, Isabelle; Billieux, Joël; Bayard, Sophie

2015-06-30

We aimed to compare adult patients with attention deficit hyperactivity disorder (ADHD) and matched controls on four dimensions of impulsivity (urgency, lack of premeditation, lack of perseverance, and sensation seeking) and to examine the association between impulsivity and ADHD symptoms. The study was conducted on 219 participants: 72 adult ADHD patients and 147 aged and gender matched controls. All participants completed questionnaires measuring the various facets of impulsivity (UPPS Impulsive Behavior Scale), ADHD and depressive symptoms severity. Patients were also assessed for ADHD subtypes, mood disorders, and addictive behaviors. ADHD patients exhibited higher urgency, lower premeditation and lower perseverance in comparison to controls. Lack of perseverance showed the strongest association with ADHD (area under curve=0.95). Patients with combined inattentive and hyperactive/impulsive subtypes reported more frequently substance abuse problems and had higher scores on urgency and sensation seeking dimensions of impulsivity than those with predominantly inattentive subtype. We report for the first time a multidimensional evaluation of impulsivity in adult ADHD patients. The UPPS Impulsive Behavior Scale may constitute a useful screening tool for ADHD in adults and may help to further understanding the psychological mechanisms underlying the differences between the ADHD subgroups. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Modulating terrestrial impacts from Oort cloud comets by the adiabatically changing galactic tides

NASA Astrophysics Data System (ADS)

Matese, J. J.; Whitman, P. G.; Innanen, K. A.; Valtonen, M. J.

Time modulation of the flux of new Jupiter-dominated Oort cloud comets is the subject of interest here. The major perturbation of these comets during the present epoch is due to the tidal field of the relatively smooth distribution of matter in the galactic disk. A secondary source of the near-parabolic comet flux are stars penetrating the inner Oort cloud and providing impulses that create brief comet showers. Substantial stellar-induced showers occur approximately every 100 m.y. Less frequent (but stronger) impulses due to giant molecular clouds can also perturb comets from the inner cloud. These occur on timescales of approximately equal to 500 m.y. In contrast to these infrequent stochastic shower phenomena is the continuously varying tidal-induced flux due to the galaxy. As the Sun orbits the galactic center it undergoes quasiharmonic motion about the galactic midplane, which is superimposed on the small eccentricity, near-Keplerian motion in the plane having epicycle period approximately equal to 150 m.y. In the process the galactic tidal field on the Sun/cloud system will vary causing a modulation of the observable Oort cloud flux. We have created a model of the galactic matter distribution as it affects the solar motion over a time interval ranging from 300 m.y. in the past to 100 m.y. into the future. As constraints on the disk's compact dark matter component we require consistency with the following: (1) the observed galactic rotation curve, (2) today's flux distribution of new comets, (3) the studies of K-giant distributions, and (4) the periodicity found in the terrestrial cratering record. The adiabatically varying galactic tidal torque is then determined and used to predict the time dependence of the flux. We find that a model in which approximately half the disk matter is compact is consistent with these constraints. Under such circumstances the peak-to-trough flux variation will be approx. equal to 5:1 with a full width of 9 m.y. This variability will manifest in the terrestrial cratering record and is consistent with the observed cratering periodicity, if over half of the impacts on Earth are caused by comets or asteroids that originate in the outer Oort cloud.

An Analysis of the Associations among Cognitive Impulsiveness, Reasoning Process, and Rational Decision Making

PubMed Central

Jelihovschi, Ana P. G.; Cardoso, Ricardo L.; Linhares, Alexandre

2018-01-01

Impulsivity may lead to several unfortunate consequences and maladaptive behaviors for both clinical and nonclinical people. It has a key role in many forms of psychopathology. Although literature has discussed the negative impact of impulsivity, few have emphasized the relationship between cognitive impulsiveness and decision making. The aim of this study is to investigate the effects of cognitive impulsiveness on decision making and explore the strategies used by participants to solve problems. For this purpose, we apply two measures of impulsivity: the self-report Barratt Impulsiveness Scale (BIS-11) and the performance based Cognitive Reflection Test (CRT). Moreover, we evaluate participants' reasoning processes employed to answer CRT questions based on the calculation expressions, data organization, and erasures they made while answering the CRT (note that we utilized the instruments using pen and paper). These reasoning processes are related to the role of executive functions in decision making, and its relationship with impulsiveness. The sample consists of 191 adults, who were either professionals or undergraduate students from the fields of business, management, or accounting. The results show that cognitive impulsiveness may negatively affect decision making, and that those who presented the calculation to answer the CRT questions made better decisions. Moreover, there was no difference in the strategies used by impulsive vs. nonimpulsive participants during decision making. Finally, people who inhibited their immediate answers to CRT questions performed better during decision making. PMID:29375440

Impaired Decisional Impulsivity in Pathological Videogamers

PubMed Central

Irvine, Michael A.; Worbe, Yulia; Bolton, Sorcha; Harrison, Neil A.; Bullmore, Edward T.; Voon, Valerie

2013-01-01

Background Pathological gaming is an emerging and poorly understood problem. Impulsivity is commonly impaired in disorders of behavioural and substance addiction, hence we sought to systematically investigate the different subtypes of decisional and motor impulsivity in a well-defined pathological gaming cohort. Methods Fifty-two pathological gaming subjects and age-, gender- and IQ-matched healthy volunteers were tested on decisional impulsivity (Information Sampling Task testing reflection impulsivity and delay discounting questionnaire testing impulsive choice), and motor impulsivity (Stop Signal Task testing motor response inhibition, and the premature responding task). We used stringent diagnostic criteria highlighting functional impairment. Results In the Information Sampling Task, pathological gaming participants sampled less evidence prior to making a decision and scored fewer points compared with healthy volunteers. Gaming severity was also negatively correlated with evidence gathered and positively correlated with sampling error and points acquired. In the delay discounting task, pathological gamers made more impulsive choices, preferring smaller immediate over larger delayed rewards. Pathological gamers made more premature responses related to comorbid nicotine use. Greater number of hours played also correlated with a Motivational Index. Greater frequency of role playing games was associated with impaired motor response inhibition and strategy games with faster Go reaction time. Conclusions We show that pathological gaming is associated with impaired decisional impulsivity with negative consequences in task performance. Decisional impulsivity may be a potential target in therapeutic management. PMID:24146789

Impulsivity as a mechanism linking child abuse and neglect with substance use in adolescence and adulthood.

PubMed

Oshri, Assaf; Kogan, Steve M; Kwon, Josephine A; Wickrama, K A S; Vanderbroek, Lauren; Palmer, Abraham A; MacKillop, James

2018-05-01

Emerging developmental perspectives suggest that adverse rearing environments promote neurocognitive adaptations that heighten impulsivity and increase vulnerability to risky behavior. Although studies document links between harsh rearing environments and impulsive behavior on substance use, the developmental hypothesis that impulsivity acts as mechanism linking adverse rearing environments to downstream substance use remains to be investigated. The present study investigated the role of impulsivity in linking child abuse and neglect with adult substance use using data from (a) a longitudinal sample of youth (Study 1, N = 9,421) and (b) a cross-sectional sample of adults (Study 2, N = 1,011). In Study 1, the links between child abuse and neglect and young adult smoking and marijuana use were mediated by increases in adolescent impulsivity. In Study 2, indirect links between child abuse and neglect and substance use were evidenced via delayed reward discounting and impulsivity traits. Among impulsivity subcomponents, robust indirect effects connecting childhood experiences to cigarette use emerged for negative urgency. Negative urgency, positive urgency, and sensation seeking mediated the effect of child abuse and neglect on cannabis and alcohol use. Results suggest that child abuse and neglect increases risk for substance use in part, due to effects on impulsivity. Individuals with adverse childhood experiences may benefit from substance use preventive intervention programs that target impulsive behaviors.

Mid-latency evoked potentials in self-reported impulsive aggression.

PubMed

Houston, R J; Stanford, M S

2001-02-01

The present study was conducted to examine psychophysiological differences in arousability among individuals who display impulsive aggressive outbursts. Amplitude and latency for the mid-latency evoked potentials (P1, N1 and P2) were obtained at scalp electrode sites. The evoking stimuli were three intensities (low, medium, high) of photic stimulation. Compared to non-aggressive controls, impulsive aggressive subjects showed significantly reduced P1 amplitude, which is indicative of an inefficient sensory gating mechanism. In addition, these subjects exhibited significantly larger N1 amplitude implying an enhanced orienting of attention to stimuli. Impulsive aggressive subjects also exhibited shorter P1, N1 and P2 peak latency. These results suggest that impulsive aggressive individuals may display quicker orienting and processing of stimuli in an attempt to compensate for low resting arousal levels. Finally, impulsive aggressive subjects augmented the P1-N1 component more frequently than controls, which is consistent with previous studies examining impulsivity and sensation seeking. Together, these findings extend previous work concerning the underlying physiology of impulsive aggression. It has been suggested that impulsive aggressive individuals may attempt to compensate for low resting arousal levels by engaging in stimulus seeking behaviors. Accordingly, the present findings imply similar physiological compensatory responses as demonstrated by heightened orienting of attention, processing and arousability. In addition, a compromised sensory gating system in impulsive aggressors may exacerbate such circumstances, and lead to later cognitive processing deficits.

Impulsivity Moderates Subjective Responses to Alcohol in Alcohol-Dependent Individuals.

PubMed

Westman, Jonathan G; Bujarski, Spencer; Ray, Lara A

2017-03-09

Studies of social drinkers indicate that subjective response (SR) to alcohol and impulsivity are risk factors for the development of alcohol use disorder which may be related. It is unclear, however, whether there are significant relationships between SR and impulsivity among individuals with alcohol dependence. Using data from an intravenous (IV) alcohol challenge study, the present study is the first to explore the relationship between impulsivity and SR during alcohol administration among alcohol-dependent individuals. Non-treatment-seeking, alcohol-dependent individuals (N = 42) completed the Delay Discounting Task to measure impulsivity and then completed two counterbalanced, placebo-controlled IV alcohol administration sessions, which included assessments of SR at breath alcohol concentration (BrAC) levels of 0.00, 0.02, 0.04 and 0.06 g/dl. Analyses revealed that more impulsive participants experienced higher subjective stimulation and positive mood in response to rising BrACs as compared to less impulsive individuals. More impulsive participants also experienced increased sedation over time regardless of condition (i.e. alcohol vs. saline). These findings suggest that among alcohol-dependent individuals, impulsivity is positively associated with the hedonic effects of alcohol as compared to placebo. High impulsivity may characterize a subset of alcohol-dependent individuals who drink to experience the rewarding effects of alcohol. © The Author 2016. Medical Council on Alcohol and Oxford University Press. All rights reserved.

Dissociable frontostriatal white matter connectivity underlies reward and motor impulsivity.

PubMed

Hampton, William H; Alm, Kylie H; Venkatraman, Vinod; Nugiel, Tehila; Olson, Ingrid R

2017-04-15

Dysfunction of cognitive control often leads to impulsive decision-making in clinical and healthy populations. Some research suggests that a generalized cognitive control mechanism underlies the ability to modulate various types of impulsive behavior, while other evidence suggests different forms of impulsivity are dissociable, and rely on distinct neural circuitry. Past research consistently implicates several brain regions, such as the striatum and portions of the prefrontal cortex, in impulsive behavior. However the ventral and dorsal striatum are distinct in regards to function and connectivity. Nascent evidence points to the importance of frontostriatal white matter connectivity in impulsivity, yet it remains unclear whether particular tracts relate to different control behaviors. Here we used probabilistic tractography of diffusion imaging data to relate ventral and dorsal frontostriatal connectivity to reward and motor impulsivity measures. We found a double dissociation such that individual differences in white matter connectivity between the ventral striatum and the ventromedial prefrontal cortex and dorsolateral prefrontal cortex was associated with reward impulsivity, as measured by delay discounting, whereas connectivity between dorsal striatum and supplementary motor area was associated with motor impulsivity, but not vice versa. Our findings suggest that (a) structural connectivity can is associated with a large amount of behavioral variation; (b) different types of impulsivity are driven by dissociable frontostriatal neural circuitry. Copyright © 2017 Elsevier Inc. All rights reserved.

Impulsivity, aggression and suicide risk among male schizophrenia patients.

PubMed

Iancu, Iulian; Bodner, Ehud; Roitman, Suzana; Piccone Sapir, Anna; Poreh, Amir; Kotler, Moshe

2010-01-01

Impulsivity has been shown to be a major variable in the etiology of suicide and aggression, but has not been researched as much in the schizophrenic population, which is characterized by serious suicide and aggression risks. 68 male schizophrenia patients responded to a battery of measures including the Positive and Negative Syndrome Scale (PANSS), the impulsivity control scale (IS), the Suicide Risk Scale (SRS) and the Overt Aggression Scale. We divided our subjects into those who received scores above and below the median on the IS. The high-impulsivity group had higher present and past rates of suicidal ideation and showed a trend for more lifetime suicidal attempts than the low-impulsivity group. The impulsivity score correlated positively with the SRS score and with some of the scores of the PANSS (the positive symptoms score, the general psychopathology score and the total score). A multiple regression analysis revealed that an older age, higher levels of aggression, high impulsivity and an elevated score on the general psychopathology subscale of the PANSS contributed positively and significantly to the explained variance of the SRS. Our study supports the contention that high impulsivity in schizophrenia patients is significant in the etiology of suicide in schizophrenia. However, the relationship between impulsivity and aggression in schizophrenia patients, and also the amelioration of impulsivity by pharmacological interventions, require further study. Copyright (c) 2010 S. Karger AG, Basel.

An Analysis of the Associations among Cognitive Impulsiveness, Reasoning Process, and Rational Decision Making.

PubMed

Jelihovschi, Ana P G; Cardoso, Ricardo L; Linhares, Alexandre

2017-01-01

Impulsivity may lead to several unfortunate consequences and maladaptive behaviors for both clinical and nonclinical people. It has a key role in many forms of psychopathology. Although literature has discussed the negative impact of impulsivity, few have emphasized the relationship between cognitive impulsiveness and decision making. The aim of this study is to investigate the effects of cognitive impulsiveness on decision making and explore the strategies used by participants to solve problems. For this purpose, we apply two measures of impulsivity: the self-report Barratt Impulsiveness Scale (BIS-11) and the performance based Cognitive Reflection Test (CRT). Moreover, we evaluate participants' reasoning processes employed to answer CRT questions based on the calculation expressions, data organization, and erasures they made while answering the CRT (note that we utilized the instruments using pen and paper). These reasoning processes are related to the role of executive functions in decision making, and its relationship with impulsiveness. The sample consists of 191 adults, who were either professionals or undergraduate students from the fields of business, management, or accounting. The results show that cognitive impulsiveness may negatively affect decision making, and that those who presented the calculation to answer the CRT questions made better decisions. Moreover, there was no difference in the strategies used by impulsive vs. nonimpulsive participants during decision making. Finally, people who inhibited their immediate answers to CRT questions performed better during decision making.

Migration of scattered teleseismic body waves

NASA Astrophysics Data System (ADS)

Bostock, M. G.; Rondenay, S.

1999-06-01

The retrieval of near-receiver mantle structure from scattered waves associated with teleseismic P and S and recorded on three-component, linear seismic arrays is considered in the context of inverse scattering theory. A Ray + Born formulation is proposed which admits linearization of the forward problem and economy in the computation of the elastic wave Green's function. The high-frequency approximation further simplifies the problem by enabling (1) the use of an earth-flattened, 1-D reference model, (2) a reduction in computations to 2-D through the assumption of 2.5-D experimental geometry, and (3) band-diagonalization of the Hessian matrix in the inverse formulation. The final expressions are in a form reminiscent of the classical diffraction stack of seismic migration. Implementation of this procedure demands an accurate estimate of the scattered wave contribution to the impulse response, and thus requires the removal of both the reference wavefield and the source time signature from the raw record sections. An approximate separation of direct and scattered waves is achieved through application of the inverse free-surface transfer operator to individual station records and a Karhunen-Loeve transform to the resulting record sections. This procedure takes the full displacement field to a wave vector space wherein the first principal component of the incident wave-type section is identified with the direct wave and is used as an estimate of the source time function. The scattered displacement field is reconstituted from the remaining principal components using the forward free-surface transfer operator, and may be reduced to a scattering impulse response upon deconvolution of the source estimate. An example employing pseudo-spectral synthetic seismograms demonstrates an application of the methodology.

Solar flare model atmospheres

NASA Technical Reports Server (NTRS)

Hawley, Suzanne L.; Fisher, George H.

1993-01-01

Solar flare model atmospheres computed under the assumption of energetic equilibrium in the chromosphere are presented. The models use a static, one-dimensional plane parallel geometry and are designed within a physically self-consistent coronal loop. Assumed flare heating mechanisms include collisions from a flux of non-thermal electrons and x-ray heating of the chromosphere by the corona. The heating by energetic electrons accounts explicitly for variations of the ionized fraction with depth in the atmosphere. X-ray heating of the chromosphere by the corona incorporates a flare loop geometry by approximating distant portions of the loop with a series of point sources, while treating the loop leg closest to the chromospheric footpoint in the plane-parallel approximation. Coronal flare heating leads to increased heat conduction, chromospheric evaporation and subsequent changes in coronal pressure; these effects are included self-consistently in the models. Cooling in the chromosphere is computed in detail for the important optically thick HI, CaII and MgII transitions using the non-LTE prescription in the program MULTI. Hydrogen ionization rates from x-ray photo-ionization and collisional ionization by non-thermal electrons are included explicitly in the rate equations. The models are computed in the 'impulsive' and 'equilibrium' limits, and in a set of intermediate 'evolving' states. The impulsive atmospheres have the density distribution frozen in pre-flare configuration, while the equilibrium models assume the entire atmosphere is in hydrostatic and energetic equilibrium. The evolving atmospheres represent intermediate stages where hydrostatic equilibrium has been established in the chromosphere and corona, but the corona is not yet in energetic equilibrium with the flare heating source. Thus, for example, chromospheric evaporation is still in the process of occurring.

The role of attention problems and impulsiveness in media violence effects on aggression.

PubMed

Swing, Edward L; Anderson, Craig A

2014-01-01

Previous research has established media violence as a causal risk factor for aggressive behavior. Several theoretical mechanisms have been identified to explain this effect. The present study assessed 422 undergraduate students to test the possibility that individual differences in attention problems and impulsiveness can help explain the link between violent media and aggression. Attention problems and impulsiveness proved to be a distinct construct from other processes believed to mediate aggression (aggressive beliefs, aggression related schemata, trait anger, and trait hostility). Attention problems and impulsiveness were uniquely related to both media exposure (total weekly hours and violent content) and aggression. Attention problems and impulsiveness were particularly related to impulsive (as opposed to premeditated) aggression. These results suggest that attention problems and impulsiveness may play an important role in violent media effects on aggression. © 2014 Wiley Periodicals, Inc.

Impulsive behavior and nicotinic acetylcholine receptors.

PubMed

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

2012-01-01

Higher impulsivity is thought to be a risk factor for drug addiction, criminal involvement, and suicide. Excessive levels of impulsivity are often observed in several psychiatric disorders including attention-deficit/hyperactivity disorder and schizophrenia. Previous studies have demonstrated that nicotinic acetylcholine receptors (nAChRs) are involved in impulsive behavior. Here, we introduce recent advances in this field and describe the role of the following nAChR-related brain mechanisms in modulating impulsive behavior: dopamine release in the ventral striatum; α4β2 nAChRs in the infralimbic cortex, which is a ventral part of the medial prefrontal cortex (mPFC); and dopamine release in the mPFC. We also suggest several potential therapeutic drugs to address these mechanisms in impulsivity-related disorders and explore future directions to further elucidate the roles of central nAChRs in impulsive behavior.

A cross-sectional examination of non-suicidal self-injury, disordered eating, impulsivity, and compulsivity in a sample of adult women.

PubMed

Black, Emma B; Mildred, Helen

2014-12-01

Non-suicidal self-injury has been classed as having both impulsive and compulsive characteristics (Simeon & Favazza, 2001). These constructs have been related to disordered eating behaviors such as vomiting (Favaro & Santonastaso, 1998). Utilizing an international sample of adult females, this paper further explored this model, aiming to identify whether all types of disordered eating could be classified as impulsive or compulsive, and whether the impulsive and compulsive groupings reflect underlying trait impulsivity and compulsivity. The hypothesized impulsive and compulsive dimensions did not emerge from the data. Notably however, all self-injurious and disordered eating behaviors were linked to Urgency (an impulsivity facet) to varying degrees; no relationship with trait compulsivity was found. These findings are discussed, study limitations are noted, and relevance for clinical practice is outlined.

Do aggressive driving and negative emotional driving mediate the link between impulsiveness and risky driving among young Italian drivers?

PubMed

Smorti, Martina; Guarnieri, Silvia

2016-01-01

The present study examined the contribution of impulsiveness and aggressive and negative emotional driving to the prediction of traffic violations and accidents taking into account potential mediation effects. Three hundred and four young drivers completed self-report measures assessing impulsiveness, aggressive and negative emotional driving, driving violations, and accidents. Structural equation modeling was used to assess the direct and indirect effects of impulsiveness on violations and accidents among young drivers through aggressive and negative emotional driving. Impulsiveness only indirectly influenced drivers' violations on the road via both the behavioral and emotional states of the driver. On the contrary, impulsiveness was neither directly nor indirectly associated with traffic accidents. Therefore, impulsiveness modulates young drivers' behavioral and emotional states while driving, which in turn influences risky driving.

Dopaminergic Therapy Increases Go Timeouts in the Go/No-Go Task in Patients with Parkinson’s Disease

PubMed Central

Yang, Xue Q.; Lauzon, Brian; Seergobin, Ken N.; MacDonald, Penny A.

2018-01-01

Parkinson’s disease (PD) is characterized by resting tremor, rigidity and bradykinesia. Dopaminergic medications such as L-dopa treat these motor symptoms, but can have complex effects on cognition. Impulse control is an essential cognitive function. Impulsivity is multifaceted in nature. Motor impulsivity involves the inability to withhold pre-potent, automatic, erroneous responses. In contrast, cognitive impulsivity refers to improper risk-reward assessment guiding behavior. Informed by our previous research, we anticipated that dopaminergic therapy would decrease motor impulsivity though it is well known to enhance cognitive impulsivity. We employed the Go/No-go paradigm to assess motor impulsivity in PD. Patients with PD were tested using a Go/No-go task on and off their normal dopaminergic medication. Participants completed cognitive, mood, and physiological measures. PD patients on medication had a significantly higher proportion of Go trial Timeouts (i.e., trials in which Go responses were not completed prior to a deadline of 750 ms) compared to off medication (p = 0.01). No significant ON-OFF differences were found for Go trial or No-go trial response times (RTs), or for number of No-go errors. We interpret that dopaminergic therapy induces a more conservative response set, reflected in Go trial Timeouts in PD patients. In this way, dopaminergic therapy decreased motor impulsivity in PD patients. This is in contrast to the widely recognized effects of dopaminergic therapy on cognitive impulsivity leading in some patients to impulse control disorders. Understanding the nuanced effects of dopaminergic treatment in PD on cognitive functions such as impulse control will clarify therapeutic decisions. PMID:29354045

Increased impulsivity associated with severity of suicide attempt history in patients with bipolar disorder.

PubMed

Swann, Alan C; Dougherty, Donald M; Pazzaglia, Peggy J; Pham, Mary; Steinberg, Joel L; Moeller, F Gerard

2005-09-01

Impulsivity is a prominent and measurable characteristic of bipolar disorder that can contribute to risk for suicidal behavior. The purpose of this study was to investigate the relationship between impulsivity and severity of past suicidal behavior, a potential predictor of eventual suicide, in patients with bipolar disorder. In bipolar disorder subjects with either a definite history of attempted suicide or no such history, impulsivity was assessed with both a questionnaire (Barratt Impulsiveness Scale) and behavioral laboratory performance measures (immediate memory/delayed memory tasks). Diagnosis was determined with the Structured Clinical Interview for DSM-IV. Interviews of patients and review of records were used to determine the number of past suicide attempts and the medical severity of the most severe attempt. Subjects with a history of suicide attempts had more impulsive errors on the immediate memory task and had shorter response latencies, especially for impulsive responses. Impulsivity was highest in subjects with the most medically severe suicide attempts. Effects were not accounted for by presence of depression or mania at the time of testing. Barratt Impulsiveness Scale scores were numerically, but not significantly, higher in subjects with suicide attempts. A history of alcohol abuse was associated with greater probability of a suicide attempt. Multivariate analysis showed that ethanol abuse history and clinical state at the time of testing did not have a significant effect after impulsivity was taken into account. These results suggest that a history of severe suicidal behavior in patients with bipolar disorder is associated with impulsivity, manifested as a tendency toward rapid, unplanned responses.

Impulsivity in adolescents with major depressive disorder: A comparative tunisian study.

PubMed

Khemakhem, Khaoula; Boudabous, Jaweher; Cherif, Leila; Ayadi, Hela; Walha, Adel; Moalla, Yousr; Hadjkacem, Imen; Ghribi, Farhat

2017-08-01

The association between impulsivity and depressive disorders in adolescence has been little studied at the literature and in our country, yet impulsivity is a major risk factor for suicide. Thus we aimed on this study to evaluate impulsivity in 25 adolescents with Major Depressive Disorder MDD compared to a control sample and to analyze the correlations between impulsivity and clinical features of MDD. Employing a matched case-control design, participants included 25 adolescents with MDD and 75 controls. We have administered the Barratt Impulsivity Scale BIS-11 for the two groups to evaluate impulsivity. Semi structured interviews according DSM 5 criteria were conducted for adolescents with MDD. The Child Depressive Inventory CDI was used to measure depressive symptoms in the control sample. Adolescents with MDD were more impulsive compared to controls according to the BIS-11 in its three domains: motor (24.96±6.26 against 20.6±4.84; p=0.000), attentional (20.88±5.03 against 16.64±3.2; p=0.000) and non planning (28.2±7.26 against 24.44±4.32; p=0.02). Impulsivity was not correlated with clinical features of MDD (suicide attempts, psychiatric comorbidities, antidepressant medication …). Adolescents with MDD seem to be more impulsive than control subjects regardless their clinical features. Whether it is a specific characteristic or a symptom among others of MDD, impulsivity predicts health-related behaviors and associated damage that need to be detected and prevented in time. Copyright © 2017 Elsevier B.V. All rights reserved.

Serotonin Depletion Induces ‘Waiting Impulsivity' on the Human Four-Choice Serial Reaction Time Task: Cross-Species Translational Significance

PubMed Central

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

2014-01-01

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

Does the uptake of wagering inducements predict impulse betting on sport?

PubMed

Hing, Nerilee; Russell, Alex M T; Li, En; Vitartas, Peter

2018-03-01

Background and aims Marketing inducements for addictive products, such as wagering, can prompt impulse purchasing by triggering consumption reminders, urges, and cravings. Wagering inducements incentivize betting by providing bonus bets, money-back guarantees, deposits into betting accounts, and discounts. Their promotion during sporting events, push marketing efforts directed at consumers, and ease of uptake at the point-of-sale, may trigger betting on impulse. This study examined whether the uptake of wagering inducements predicted impulse betting on sport. Methods Australian sports bettors (N = 1,813) completed an online survey measuring their proportion of planned bets, impulse bets before match commencement, and impulse bets during play; frequency of using wagering inducements; and several psychological, behavioral, and demographic variables. Results More frequent users of wagering inducements had a greater tendency to place impulse in-play bets, which were also predicted by problem gambling, higher buying impulsiveness, higher frequency of watching sports, younger age, and higher educational status. Sports bettors with a greater tendency to place impulse bets before match commencement also tended to have higher buying impulsiveness and to be younger, but they used inducements less frequently, and tended to be female, less-educated and non-problem, moderate risk, or problem gamblers. Discussion and conclusions Uptake of wagering inducements appeared to be particularly effective in stimulating impulse in-play betting among problem gamblers and frequent sports viewers. These results suggest that a more cautious approach to the regulation of both in-play bets and wagering inducements may be required to better protect young adults from gambling problems and harm.

Effect of aging and direction of impulse in video head impulse test.

PubMed

Kim, Tae Hwan; Kim, Min-Beom

2017-09-12

The aim of this study was to identify the difference of gain value in the video head impulse test (vHIT) according to the age of the patient and the direction of the impulse. All participants were subjected to vHIT with horizontal semicircular canal (HSCC). vHIT with vertical canal (posterior and anterior semicircular canal [PSCC and ASCC]) additionally was performed in 434 participants. The mean vestibulo-ocular reflex (VOR) gain was maintained in patients in the HSCC at below 70 years (1.025 ± 0.08) and in the vertical canal at below 80 years (PSCC: 0.965 ± 0.12, ASCC: 0.975 ± 0.14). However, the decrease of VOR gain was significant in patients over 70 years in the HSCC (0.978 ± 0.35, P < .001) and in patients over 80 years in the vertical canal (PSCC: 0.828 ± 0.16, ASCC: 0.851 ± 0.13, P < .001). In addition, a VOR gain of rightward impulse was higher than the leftward impulse, but there was no difference based on the direction of impulse in the vertical impulse test. VOR gain declines with increasing age, over 70 years on the horizontal canal, and over 80 years on the vertical canal. Additionally, horizontal VOR gain of rightward impulse was higher than the leftward impulse in right-eye recordings only, but the vertical canal showed no difference of gain according to the direction of impulse. 2b. Laryngoscope, 2017. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

A STUDY OF METHODS OF CONTROLLING IMPULSES.

ERIC Educational Resources Information Center

WHITESIDE, RAY

THE PERSON LESS ABLE TO CONTROL HIS IMPULSES IS ALSO APT TO EXHIBIT SOCIALLY DISVALUED BEHAVIOR. VOCATIONAL AND ACADEMIC FAILURE IS A PARTIAL CONSEQUENCE OF IMPULSIVENESS AND LACK OF SELF-CONTROL. TO INVESTIGATE IMPULSE CONTROL, TWO INSTRUMENTS BELIEVED TO MEASURE ATTRIBUTES OF OPPOSITE POLES OF THIS CONCEPT (SEQUENTIAL TESTS OF EDUCATIONAL…

Measuring Impulsivity in Adolescents with Serious Substance and Conduct Problems

ERIC Educational Resources Information Center

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

2006-01-01

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

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

PubMed

Guan, Zhi-Hong; Liu, Na

2010-03-01

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

Ascent performance feasibility for next-generation spacecraft

NASA Astrophysics Data System (ADS)

Mancuso, Salvatore Massimo

This thesis deals with the optimization of the ascent trajectories for single-stage suborbital (SSSO), single-stage-to-orbit (SSTO), and two-stage-to-orbit (TSTO) rocket-powered spacecraft. The maximum payload weight problem has been solved using the sequential gradient-restoration algorithm. For the TSTO case, some modifications to the original version of the algorithm have been necessary in order to deal with discontinuities due to staging and the fact that the functional being minimized depends on interface conditions. The optimization problem is studied for different values of the initial thrust-to-weight ratio in the range 1.3 to 1.6, engine specific impulse in the range 400 to 500 sec, and spacecraft structural factor in the range 0.08 to 0.12. For the TSTO configuration, two subproblems are studied: uniform structural factor between stages and nonuniform structural factor between stages. Due to the regular behavior of the results obtained, engineering approximations have been developed which connect the maximum payload weight to the engine specific impulse and spacecraft structural factor; in turn, this leads to useful design considerations. Also, performance sensitivity to the scale of the aerodynamic drag is studied, and it is shown that its effect on payload weight is relatively small, even for drag changes approaching ± 50%. The main conclusions are that: the design of a SSSO configuration appears to be feasible; the design of a SSTO configuration might be comfortably feasible, marginally feasible, or unfeasible, depending on the parameter values assumed; the design of a TSTO configuration is not only feasible, but its payload appears to be considerably larger than that of a SSTO configuration. Improvements in engine specific impulse and spacecraft structural factor are desirable and crucial for SSTO feasibility; indeed, it appears that aerodynamic improvements do not yield significant improvements in payload weight.

Prevalence and Correlates of Direct Self-Injurious Behavior among Chinese Adolescents: Findings from a Multicenter and Multistage Survey.

PubMed

Xin, Xiuhong; Wang, Yuping; Fang, Jianqun; Ming, Qingsen; Yao, Shuqiao

2017-05-01

Direct self-injurious behavior (DSIB) has become an important focus due to its perniciousness and perplexity. Little is known about its prevalence and correlative factors in Chinese adolescents, including how data may differ according to gender. A multicenter, multistage stratified cluster random sampling was used to examine the previous 12-month prevalence of DSIB, as well as the possible correlates of demographics, risky behaviors, suicidality, and psychosocial factors associated with DSIB in a school-based sample of 11,880 students (49.5 % boys and 50.5 % girls). Approximately 30 % of the adolescents in the sample reported at least one incident of DSIB in the past 12-month period. After controlling for demographic variables, analyses of the independent relationships of DSIB with risky behaviors, suicidality, and psychosocial factors were conducted for each gender. Smoking, binge drinking, running away from home, suicide ideation, suicide plans, positive affect, and physical symptoms were identified as common factors associated with DSIB for both genders in the final model. In addition, truancy, fighting, physical inactivity, motor impulsiveness, and depressed affect were found to be related to DSIB in boys, whereas suicide attempts and somatic complaints were found to be related to DSIB in girls. Separation anxiety and social anxiety associated negatively with DSIB in boys and girls, respectively. DSIB was not found to independently relate to attention impulsiveness, non-planned impulsiveness, self-esteem, or harm avoidance in either genders. DSIB was prevalent in Chinese adolescents. Programs intended to promote physical and mental health in adolescents should take into account gender differences in DSIB-associated factors, including risky behaviors, suicidality, and psychosocial factors.

The influence of the aquatic environment on the center of pressure, impulses and upper and lower trunk accelerations during gait initiation.

PubMed

Marinho-Buzelli, Andresa R; Masani, Kei; Rouhani, Hossein; Barela, Ana M; Fernandes, Gustavo T B; Verrier, Mary C; Popovic, Milos R

2017-10-01

Gait initiation is defined as the transition from stationary standing to steady-state walking. Despite the frequent use of therapy pools for training walking in early stages of rehabilitation, none have been reported on the effects of immersion on gait initiation. We aimed to analyze the center of pressure (COP) trajectories, the vertical and anteroposterior impulses and upper and lower trunk accelerations during anticipatory (APA) and execution phases of gait initiation. In the COP trajectory, the execution (EXE) phase was further subdivided in two phases: predominantly mediolateral (EXE1), and predominantly anteroposterior (EXE2). Able-bodied participants initiated gait while standing on a force plate and walked approximately 4 steps following a visual cue. The participants were wearing three inertial sensors placed on the lower and upper trunk, and on the stance shank. Individuals performed 10 trials each on land and in water, in two consecutive days. The lengths and velocities of COP trajectories increased in water compared to land during APA, while the COP length increased and the COP velocity reduced in water during EXE2. The anteroposterior impulses increased in water during EXE. Lower trunk acceleration was smaller in water while the upper trunk acceleration did not differ, resulting in the larger ratio of upper to lower trunk acceleration in water during EXE. Overall, immersion in water increases COP length during gait initiation, and reduces COP velocity during EXE2, indicating a new postural strategy in water. The aquatic medium may be favorable for individuals who need weight support, gradual resistance and a longer time to execute gait initiation. Copyright © 2017 Elsevier B.V. All rights reserved.

Anticonvulsant medications attenuate amphetamine-induced deficits in behavioral inhibition but not decision making under risk on a rat gambling task.

PubMed

Tremblay, Melanie; Winstanley, Catharine A

2016-11-01

Impulsivity is a major component of mania in bipolar disorder (BD), and patients also show impairments in decision-making involving risk on the Iowa Gambling Task (IGT). Similar deficits are observed in some patients with temporal lobe epilepsy (TLE), and incidence of problem gambling is higher in both these populations. Anticonvulsant drugs are widely used in the treatment of epilepsy, but also as mood stabilizers and prophylaxis for the management of BD. Unfortunately, little is still known about the precise mechanisms of action underlying their efficacy, and the specific behavioral aspect targeted by these drugs. This project explored the effect of the three anticonvulsant drugs currently also used as mood stabilizers- carbamazepine, valproate and lamotrigine on aspects of decision-making using a rat analogue of the IGT, the rat Gambling Task (rGT). In this task, rats choose between four distinct, probabilistic reinforcement schedules. Sugar pellet profits are maximized by adopting a conservative strategy, avoiding tempting high-risk, high-reward options. Effects of the anticonvulsant agents were assessed on baseline performance and also in conjunction with amphetamine administration, in order to approximate a "mania-like" state. Carbamazepine appeared to slow processing speed, decreasing premature responses and increasing choice latency, whereas valproate and lamotrigine had no effect. When administered prior to amphetamine, lamotrigine was the only drug that failed to attenuate the pro-impulsive effect of the psychostimulant. Further studies looking at chronic administration of anticonvulsants may help us understand the impact of this medication class on decision-making and impulsivity in healthy rats and disease models. Copyright © 2016 Elsevier B.V. All rights reserved.

Bifurcation Analysis and Application for Impulsive Systems with Delayed Impulses

NASA Astrophysics Data System (ADS)

Church, Kevin E. M.; Liu, Xinzhi

In this article, we present a systematic approach to bifurcation analysis of impulsive systems with autonomous or periodic right-hand sides that may exhibit delayed impulse terms. Methods include Lyapunov-Schmidt reduction and center manifold reduction. Both methods are presented abstractly in the context of the stroboscopic map associated to a given impulsive system, and are illustrated by way of two in-depth examples: the analysis of a SIR model of disease transmission with seasonality and unevenly distributed moments of treatment, and a scalar logistic differential equation with a delayed census impulsive harvesting effort. It is proven that in some special cases, the logistic equation can exhibit a codimension two bifurcation at a 1:1 resonance point.

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

PubMed

Zhang, Jie; Lin, Lin

2015-07-01

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

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

NASA Technical Reports Server (NTRS)

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

1988-01-01

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maeno, Akihiro; Yamamoto, Naoji; Nakashima, Hideki

2011-08-15

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

Observations of the 3-D distribution of interplanetary electrons and ions from solar wind plasma to low energy cosmic rays

NASA Technical Reports Server (NTRS)

Lin, R. P.; Anderson, K. A.; Ashford, S.; Carlson, C.; Curtis, D.; Ergun, R.; Larson, D.; McFadden, J.; McCarthy, M.; Parks, G. K.

1995-01-01

The 3-D Plasma and Energetic Particle instrument on the GGS Wind spacecraft (launched November 1, 1994) is designed to make measurements of the full three-dimensional distribution of suprathermal electrons and ions from solar wind plasma to low energy cosmic rays, with high sensitivity, wide dynamic range, good energy and angular resolution, and high time resolution. Three pairs of double-ended telescopes, each with two or three closely sandwiched passivated ion implanted silicon detectors measure electrons and ions from approximately 20 keV to greater than or equal to 300 keV. Four top-hat symmetrical spherical section electrostatic analyzers with microchannel plate detectors, a large and a small geometric factor analyzer for electrons and a similar pair for ions, cover from approximately 3 eV to 30 keV. We present preliminary observations of the electron and ion distributions in the absence of obvious solar impulsive events and upstream particles. The quiet time electron energy spectrum shows a smooth approximately power law fall-off extending from the halo population at a few hundred eV to well above approximately 100 keV The quiet time ion energy spectrum also shows significant fluxes over this energy range. Detailed 3-D distributions and their temporal variations will be presented.

Are executive function and impulsivity antipodes? A conceptual reconstruction with special reference to addiction

PubMed Central

Bickel, Warren K.; Jarmolowicz, David P.; Mueller, E. Terry; Gatchalian, Kirstin M.; McClure, Samuel M.

2014-01-01

Rationale Although there is considerable interest in how either executive function (EF) or impulsivity relate to addiction, there is little apparent overlap between these research areas. Objectives The present paper aims to determine if components of these two constructs are conceptual antipodes—widely separated on a shared continuum. Methods EFs and impulsivities were compared and contrasted. Specifically, the definitions of the components of EF and impulsivity, the methods used to measure the various components, the populations of drug users that show deficits in these components, and the neural substrates of these components were compared and contrasted. Results Each component of impulsivity had an antipode in EF. EF, however, covered a wider range of phenomena, including compulsivity. Conclusions Impulsivity functions as an antipode of certain components of EF. Recognition of the relationship between EF and impulsivity may inform the scientific inquiry of behavioral problems such as addiction. Other theoretical implications are discussed. PMID:22441659

Impulsivity, self-control, and hypnotic suggestibility.

PubMed

Ludwig, V U; Stelzel, C; Krutiak, H; Prunkl, C E; Steimke, R; Paschke, L M; Kathmann, N; Walter, H

2013-06-01

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. Copyright © 2013 Elsevier Inc. All rights reserved.

Impulse noise generator--design and operation.

PubMed

Brinkmann, H

1991-01-01

In the seventies PFANDER (Pfander, 1975) proposed a screening test with an impulse noise simulator to check the particular responsivity of soldiers on vulnerability of the inner ear concerning the impulse noise-induced hearing loss. According to a system developed at the University of Oldenburg (Germany) (Klug & Radek, 1987), we have constructed an impulse noise generator designed for our specific requirements that will be presented. The simulator consists of an electrical ignited impulse noise spark gap which is supplied by a 3.5 kV high voltage source. At a distance of 1.10 m from the center of the impulse noise spark gap a peak pressure level of 155 dB with a C-Duration (Pfander, 1975) of .2 msec and with the main energy in the frequency range from 1 kHz to 2 kHz was good reproducible. It would be preferable to shift the impulse noise spectrum to lower frequencies but experimental effort has failed so far.

Reconsidering the link between impulsivity and suicidal behavior.

PubMed

Anestis, Michael D; Soberay, Kelly A; Gutierrez, Peter M; Hernández, Theresa D; Joiner, Thomas E

2014-11-01

It is widely accepted that suicidal behavior often occurs with little planning. We propose, however, that suicidal behavior is rarely if ever impulsive-that it is too frightening and physically distressing to engage in without forethought-and that suicidal behavior in impulsive individuals is accounted for by painful and fearsome behaviors capable of enhancing their capacity for suicide. We conducted a meta-analysis of the association between trait impulsivity and suicidal behavior and a critical review of research considering the impulsiveness of specific suicide attempts. Meta-analytic results suggest the relationship between trait impulsivity and suicidal behavior is small. Furthermore, studies examining a mediating role of painful and provocative behaviors have uniformly supported our model. Results from our review suggest that researchers have been unable to adequately measure impulsivity of attempts and that measures sensitive to episodic planning must be developed to further our understanding of this phenomenon. © 2014 by the Society for Personality and Social Psychology, Inc.

Impulsivity moderates the relationship between previous quit failure and cue-induced craving.

PubMed

Erblich, Joel; Michalowski, Alexandra

2015-12-01

Poor inhibitory control has been shown to be an important predictor of relapse to a number of drugs, including nicotine. Indeed, smokers who exhibit higher levels of impulsivity are thought to have impaired regulation of urges to smoke, and previous research has suggested that impulsivity may moderate cue-induced cigarette cravings. To that end, we conducted a study to evaluate the interplay between failed smoking cessation, cue-induced craving, and impulsivity. Current smokers (n=151) rated their cigarette cravings before and after laboratory to exposure to smoking cues, and completed questionnaires assessing impulsivity and previous failed quit attempts. Findings indicated that shorter duration of previous failed quit attempts was related to higher cue-induced cigarette craving, especially among smokers with higher levels of impulsivity. Results underscore the importance of considering trait impulsivity as a factor in better understanding the management of cue-induced cravings. Copyright © 2015 Elsevier Ltd. All rights reserved.

Impulsivity Moderates the Relationship between Previous Quit Failure and Cue-induced Craving

PubMed Central

Erblich, Joel; Michalowski, Alexandra

2015-01-01

Introduction Poor inhibitory control has been shown to be an important predictor of relapse to a number of drugs, including nicotine. Indeed, smokers who exhibit higher levels of impulsivity are thought to have impaired regulation of urges to smoke, and previous research has suggested that impulsivity may moderate cue-induced cigarette cravings. To that end, we conducted a study to evaluate the interplay between failed smoking cessation, cue-induced craving, and impulsivity. Methods Current smokers (n=151) rated their cigarette cravings before and after laboratory to exposure to smoking cues, and completed questionnaires assessing impulsivity and previous failed quit attempts. Results Findings indicated that shorter duration of previous failed quit attempts was related to higher cue-induced cigarette craving, especially among smokers with higher levels of impulsivity. Conclusions Results underscore the importance of considering trait impulsivity as a factor in better understanding the management of cue-induced cravings. PMID:26183443

Alcoholics Anonymous and Reduced Impulsivity: A Novel Mechanism of Change

PubMed Central

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

2012-01-01

Reduced impulsivity is a novel, yet plausible, mechanism of change associated with the salutary effects of Alcoholics Anonymous (AA). Here, we review our work on links between AA attendance and reduced impulsivity using a 16-year prospective study of men and women with alcohol use disorders (AUD) who were initially untreated for their drinking problems. Across the study period, there were significant mean-level decreases in impulsivity, and longer AA duration was associated with reductions in 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 AUD. PMID:23327499

Single cell manipulation utilizing femtosecond laser-induced shock and stress waves

NASA Astrophysics Data System (ADS)

Hosokawa, Yoichiroh

2017-02-01

When an intense femtosecond laser pulse is focused into a culture medium through an objective lens, an impulsive force is loaded on the cells with generations of the shock and stress waves at the laser focal point. The shock and stress waves were acted to single cells in the vicinity of the laser focal point as an impulsive force. We have applied the impulsive force to manipulate single cells. As the transient intensity of the impulsive force is over 1000 times stronger than the force due to optical tweezers, drastic single manipulation which is difficult by the optical tweezers can be realized. The generation process of the impulsive force and behavior of animal cell after loading the impulsive force were reviewed, and then our original quantification method of the impulsive force utilizing atomic force microscope (AFM) was introduced with its applications for evaluating adhesions between animal cells and between sub-organelles in plant cell.

The Effect of Individual Differences on Adolescents' Impulsive Buying Behavior

ERIC Educational Resources Information Center

Lin, Chien-Huang; Chuang, Shin-Chieh

2005-01-01

This study posits a relationship between Emotional Intelligence (EI) and Impulsive Buying Tendency (IBT). A survey of 574 adolescents found that high-EI adolescents manifested less impulsive behavior than did low-EI adolescents, and high-IBT adolescents were more likely to engage in more impulsive buying behavior than were low-IBT adolescents.…

46 CFR 160.040-4 - Equipment for impulse-projected rocket type line-throwing appliance.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 6 2013-10-01 2013-10-01 false Equipment for impulse-projected rocket type line...-Throwing Appliance, Impulse-Projected Rocket Type (and Equipment) § 160.040-4 Equipment for impulse-projected rocket type line-throwing appliance. (a) Four rocket projectiles, each complete with bridle and...

46 CFR 160.040-4 - Equipment for impulse-projected rocket type line-throwing appliance.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 6 2012-10-01 2012-10-01 false Equipment for impulse-projected rocket type line...-Throwing Appliance, Impulse-Projected Rocket Type (and Equipment) § 160.040-4 Equipment for impulse-projected rocket type line-throwing appliance. (a) Four rocket projectiles, each complete with bridle and...

46 CFR 160.040-4 - Equipment for impulse-projected rocket type line-throwing appliance.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 6 2014-10-01 2014-10-01 false Equipment for impulse-projected rocket type line...-Throwing Appliance, Impulse-Projected Rocket Type (and Equipment) § 160.040-4 Equipment for impulse-projected rocket type line-throwing appliance. (a) Four rocket projectiles, each complete with bridle and...

46 CFR 160.040-4 - Equipment for impulse-projected rocket type line-throwing appliance.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 6 2010-10-01 2010-10-01 false Equipment for impulse-projected rocket type line...-Throwing Appliance, Impulse-Projected Rocket Type (and Equipment) § 160.040-4 Equipment for impulse-projected rocket type line-throwing appliance. (a) Four rocket projectiles, each complete with bridle and...

46 CFR 160.040-4 - Equipment for impulse-projected rocket type line-throwing appliance.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 6 2011-10-01 2011-10-01 false Equipment for impulse-projected rocket type line...-Throwing Appliance, Impulse-Projected Rocket Type (and Equipment) § 160.040-4 Equipment for impulse-projected rocket type line-throwing appliance. (a) Four rocket projectiles, each complete with bridle and...

Bayesian Threshold Estimation

ERIC Educational Resources Information Center

Gustafson, S. C.; Costello, C. S.; Like, E. C.; Pierce, S. J.; Shenoy, K. N.

2009-01-01

Bayesian estimation of a threshold time (hereafter simply threshold) for the receipt of impulse signals is accomplished given the following: 1) data, consisting of the number of impulses received in a time interval from zero to one and the time of the largest time impulse; 2) a model, consisting of a uniform probability density of impulse time…

Allelic variation in dopamine D2 receptor gene is associated with attentional impulsiveness on the Barratt Impulsiveness Scale (BIS-11).

PubMed

Taylor, Jasmine B; Cummins, Tarrant D R; Fox, Allison M; Johnson, Beth P; Tong, Janette H; Visser, Troy A W; Hawi, Ziarih; Bellgrove, Mark A

2017-01-20

Previous studies have postulated that noradrenergic and/or dopaminergic gene variations are likely to underlie individual differences in impulsiveness, however, few have shown this. The current study examined the relationship between catecholamine gene variants and self-reported impulsivity, as measured by the Barratt Impulsiveness Scale (Version 11; BIS-11) Methods: Six hundred and seventy-seven non-clinical adults completed the Barratt Impulsiveness Scale (BIS-11). DNA was analysed for a set of 142 single-nucleotide polymorphisms (SNPs) across 20 autosomal catecholamine genes. Association was tested using an additive regression model with permutation testing used to control for the influence of multiple comparison. Analysis revealed an influence of rs4245146 of the dopamine D2 receptor (DRD2) gene on the BIS-11 attention first-order factor, such that self-reported attentional impulsiveness increased in an additive fashion with each copy of the T allele. These findings provide preliminary evidence that allelic variation in DRD2 may influence impulsiveness by increasing the propensity for attentional lapses.

Impulsivity and compulsive buying are associated in a non-clinical sample: an evidence for the compulsivity-impulsivity continuum?

PubMed

Paula, Jonas J de; Costa, Danielle de S; Oliveira, Flavianne; Alves, Joana O; Passos, Lídia R; Malloy-Diniz, Leandro F

2015-01-01

Compulsive buying is controversial in clinical psychiatry. Although it is defined as an obsessive-compulsive disorder, other personality aspects besides compulsivity are related to compulsive buying. Recent studies suggest that compulsivity and impulsivity might represent a continuum, with several psychiatric disorders lying between these two extremes. In this sense, and following the perspective of dimensional psychiatry, symptoms of impulsivity and compulsivity should correlate even in a non-clinical sample. The present study aims to investigate whether these two traits are associated in a healthy adult sample. We evaluated 100 adults, with no self-reported psychiatric disorders, using the Barratt Impulsiveness Scale-11 and two scales of compulsive buying. Using multiple linear regressions, we found that impulsivity accounted for about 15% of variance in the compulsive-buying measure. Our results suggest that an association between impulsivity and compulsive buying occurs even in non-clinical samples, evidence that compulsivity and impulsivity might form a continuum and that compulsive buying might be an intermediate condition between these two personality traits.

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

PubMed

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

2015-07-01

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

Frequency modulation television analysis: Threshold impulse analysis. [with computer program

NASA Technical Reports Server (NTRS)

Hodge, W. H.

1973-01-01

A computer program is developed to calculate the FM threshold impulse rates as a function of the carrier-to-noise ratio for a specified FM system. The system parameters and a vector of 1024 integers, representing the probability density of the modulating voltage, are required as input parameters. The computer program is utilized to calculate threshold impulse rates for twenty-four sets of measured probability data supplied by NASA and for sinusoidal and Gaussian modulating waveforms. As a result of the analysis several conclusions are drawn: (1) The use of preemphasis in an FM television system improves the threshold by reducing the impulse rate. (2) Sinusoidal modulation produces a total impulse rate which is a practical upper bound for the impulse rates of TV signals providing the same peak deviations. (3) As the moment of the FM spectrum about the center frequency of the predetection filter increases, the impulse rate tends to increase. (4) A spectrum having an expected frequency above (below) the center frequency of the predetection filter produces a higher negative (positive) than positive (negative) impulse rate.

Association between Internet gaming disorder and adult attention deficit and hyperactivity disorder and their correlates: Impulsivity and hostility.

PubMed

Yen, Ju-Yu; Liu, Tai-Ling; Wang, Peng-Wei; Chen, Cheng-Sheng; Yen, Cheng-Fang; Ko, Chih-Hung

2017-01-01

Internet gaming disorder (IGD) and attention deficit and hyperactivity disorder (ADHD) are associated with impulsivity and hostility. This study evaluated the associations among ADHD, impulsivity, hostility, and IGD. We recruited 87 individuals with IGD and 87 controls without a history of IGD. All participants underwent a diagnostic interview based on the DSM-5 IGD criteria and DSM-IV-TR ADHD criteria and completed a questionnaire regarding impulsivity and hostility. The information from the diagnostic interviews was assessed using the clinical global impression scale. The results suggested that IGD is associated with ADHD among young adults and that young adults with both IGD and ADHD have higher impulsivity and hostility. Furthermore, impulsivity and hostility mediate the association between ADHD and IGD. Thus, ADHD is a common comorbidity of IGD among young adults, and impulsivity and hostility are major factors involved in comorbid ADHD and IGD. Young adults with ADHD should be thoroughly assessed, particularly for their impulsivity and hostility, and interventions for IGD should be developed. Copyright © 2016. Published by Elsevier Ltd.

Individual Differences in Impulsivity Predict Anticipatory Eye Movements

PubMed Central

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

2011-01-01

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

Choice Impulsivity: Definitions, Measurement Issues, and Clinical Implications

PubMed Central

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

2015-01-01

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

An Impulse Based Substructuring approach for impact analysis and load case simulations

NASA Astrophysics Data System (ADS)

Rixen, Daniel J.; van der Valk, Paul L. C.

2013-12-01

In the present paper we outline the basic theory of assembling substructures for which the dynamics are described as Impulse Response Functions. The assembly procedure computes the time response of a system by evaluating per substructure the convolution product between the Impulse Response Functions and the applied forces, including the interface forces that are computed to satisfy the interface compatibility. We call this approach the Impulse Based Substructuring method since it transposes to the time domain the Frequency Based Substructuring approach. In the Impulse Based Substructuring technique the Impulse Response Functions of the substructures can be gathered either from experimental tests using a hammer impact or from time-integration of numerical submodels. In this paper the implementation of the method is outlined for the case when the impulse responses of the substructures are computed numerically. A simple bar example is shown in order to illustrate the concept. The Impulse Based Substructuring allows fast evaluation of impact response of a structure when the impulse response of its components is known. It can thus be used to efficiently optimize designs of consumer products by including impact behavior at the early stage of the design, but also for performing substructured simulations of complex structures such as offshore wind turbines.

Cognitive correlates in panic disorder as related to impulsivity - preliminary report.

PubMed

Jakuszkowiak-Wojten, Katarzyna; Gałuszko-Węgielnik, Maria; Raczak, Alicja; Cubała, Wiesław Jerzy; Wiglusz, Mariusz Stanisław; Herstowska, Marta; Landowski, Jerzy

2012-09-01

Impulsivity is the neurophysiologically based inability to confirm behaviour to its context or consequences. Overimpulsiveness characterizes many mental disorders and poses an important clinical dilemma. Although the relationship between mood disorders and impulsivity has been well studied the relationship between anxiety and impulsivity is controversial and not well explored. Some studies hypothesise that patients with the diagnosis of panic disorders are characterised by higher levels of impulsivity as a trait as compared to healthy individuals. The aim of this study was to assess cognitive correlates in panic disorder as related to impulsivity measures. Within the preliminary studies four patients diagnosed with panic disorder (DSM-IV-TR) were studied. The severity measure was the Panic and Agoraphobia Scale. The experimental group comprised of psychotropic drug naive patients. Impulsiveness was evaluated with the Barrat Impulsiveness Scale - 11th version (BIS-11). To asses cognitive functions we used CANTAB (Cambridge Neuropsychological Test Automated Battery). BIS-11 scores observed in the group of psychotropic drug naive patients with panic disorder were higher than the adjusted average for the population and correlated with the number of mistakes in CANTAB (Spatial Working Memory Test); rs=0.949; p=0.0513. The preliminary findings indicate a correlation between impulsivity and cognitive deficits in panic disorder in psychotropic drug naive patients.

The effects of heroin administration and drug cues on impulsivity.

PubMed

Jones, Jermaine D; Vadhan, Nehal P; Luba, Rachel R; Comer, Sandra D

2016-08-01

Drug addiction is a chronic relapsing disorder characterized by compulsive drug seeking and continued use despite negative consequences. Behavioral impulsivity is a strong predictor of the initiation and maintenance of drug addiction. Preclinical data suggest that heroin may exacerbate impulsive characteristics in an individual but this has yet to be assessed in clinical samples. The current secondary data analysis sought to investigate the effects of heroin on impulsivity along with the effects of exposure to drug cues. Using the current data set, we also tentatively assessed the etiological relationship between impulsivity and heroin abuse. Sixteen heroin-dependent participants were recruited to complete Immediate Memory Task/Delayed Memory Task (IMT/DMT) and GoStop tasks following repeated heroin administration, following acute heroin administration, and following a drug cue exposure session. Four preceding days of active heroin availability, compared to four preceding days of placebo drug availability, increased impulsivity assessed using the IMT and DMT. Presentation of drug cues similarly acted to increase impulsivity assessments on all three tasks. It also appears that heavier users were more susceptible to the influence of drug cues on impulsivity. The present study represents a step toward a more comprehensive understanding of the interaction between opioid abuse and impulsivity. A better understanding of these factors could provide critical insight into the maintenance of heroin use and relapse.

Does alcohol craving mediate the impulsivity-aggression relationship in recently detoxified alcohol-dependent patients?

PubMed

Roozen, H G; Wetering, B J M van de; Franken, I H A

2013-01-01

The relationship between the use of alcohol and aggression is complex and represents major public health issues. Delving into the nature of this association is vital, since various underlying factors may contribute to the expression of aggression. This study examined trait aggression by assessing correlates and, subsequently, the unique contribution of alcohol craving, and dysfunctional impulsivity, by means of correlational and mediational analyses. Forty inpatient detoxified alcohol-dependent patients were recruited. These participants completed the Desire for Alcohol Questionnaire (DAQ), Dickman Impulsivity Inventory (DII), and the Aggression Questionnaire (AQ). The findings indicated that aggression, dysfunctional impulsivity, and alcohol craving were all positively intercorrelated. The association between dysfunctional impulsivity and aggression was robust. The mediational analyses yielded that craving partially mediated this relationship, although not very substantial. It was shown that impulsivity, as a personality characteristic, is strongly associated with aggressive behaviors, whereby the impact of craving on the relationship between impulsivity and trait aggression in alcohol-dependent inpatients was weak. Since it has been posited that factors such as impulsivity and craving may contribute to the lucid association between substance use and aggression, these findings mirror previous research on stimulant users and, subsequently, substantiates that craving exerts only a minor weight on the strong impulsivity-aggression relationship.

Impulsivity and Clinical Symptoms among Adolescents with Non-Suicidal Self-Injury with or without Attempted Suicide

PubMed Central

Dougherty, Donald M.; Mathias, Charles W.; Marsh-Richard, Dawn M.; Prevette, Kristen N.; Dawes, Michael A.; Hatzis, Erin S.; Palmes, Guy; Nouvion, Sylvain O.

2011-01-01

This study examined clinical characteristics and laboratory-measured impulsive behavior of adolescents engaging in either non-suicidal self-injury with (NSSI+SA; n = 25) or without (NSSI-Only; n = 31) suicide attempts. We hypothesized that adolescent with NSSI+SI would exhibit more severe clinical symptoms and higher levels of behavioral impulsivity compared to adolescents with NSSI-Only. Adolescents were recruited from an inpatient psychiatric hospital unit and the two groups were compared on demographic characteristics, psychopathology, self-reported clinical ratings, methods of non-suicidal self-injury, and two laboratory impulsivity measures. Primary evaluations were conducted during psychiatric hospitalization, and a subset of those tested during hospitalization was retested 4-6 weeks after discharge. During hospitalization, NSSI+SA patients reported worse depression, hopelessness, and impulsivity on standard clinical measures, and demonstrated elevated impulsivity on a reward-directed laboratory measure compared to NSSI-Only patients. In the preliminary follow-up analyses, depression, hopelessness, suicidal ideation, and laboratory impulsivity were improved for both groups, but the NSSI+SA group still exhibited significantly more depressive symptoms, hopelessness, and impulsivity than the NSSI-Only group. Risk assessments for adolescents with NSSI+SA should include consideration not only of the severity of clinical symptoms but of the current level impulsivity as well. PMID:19631392

Testing the Relations Between Impulsivity-Related Traits, Suicidality, and Nonsuicidal Self-Injury: A Test of the Incremental Validity of the UPPS Model

PubMed Central

Lynam, Donald R.; Miller, Joshua D.; Miller, Drew J.; Bornovalova, Marina A.; Lejuez, C. W.

2011-01-01

Borderline personality disorder (BPD) has received significant attention as a predictor of suicidal behavior (SB) and nonsuicidal self-injury (NSSI). Despite significant promise, trait impulsivity has received less attention. Understanding the relations between impulsivity and SB and NSSI is confounded, unfortunately, by the heterogeneous nature of impulsivity. This study examined the relations among 4 personality pathways to impulsive behavior studied via the UPPS model of impulsivity and SB and NSSI in a residential sample of drug abusers (N = 76). In this study, we tested whether these 4 impulsivity-related traits (i.e., Negative Urgency, Sensation Seeking, Lack of Premeditation, and Lack of Perseverance) provide incremental validity in the statistical prediction of SB and NSSI above and beyond BPD; they do. We also tested whether BPD symptoms provide incremental validity in the prediction of SB and NSSI above and beyond these impulsivity-related traits; they do not. In addition to the main effects of Lack of Premeditation and Negative Urgency, we found evidence of a robust interaction between these 2 personality traits. The current results argue strongly for the consideration of these 2 impulsivity-related domains—alone and in interaction—when attempting to understand and predict SB and NSSI. PMID:21833346

The mediating role of non-suicidal self-injury in the relationship between impulsivity and suicidal behavior among inpatients receiving treatment for substance use disorders.

PubMed

Anestis, Michael D; Tull, Matthew T; Lavender, Jason M; Gratz, Kim L

2014-08-15

Several theories posit a direct role of impulsivity in suicidal behavior. The interpersonal-psychological theory of suicidal behavior (IPTS) argues that the relationship between impulsivity and suicidal behavior is explained by the painful and/or provocative experiences (PPEs) often encountered by impulsive individuals. It thus seems plausible that nonsuicidal self-injury (NSSI), itself associated with impulsivity, might account for the relationship between impulsivity and suicidal behavior. We examined data from 93 adult inpatients (54.8% male) seeking treatment for substance use disorders. Patients completed a structured interview assessing prior suicidal behavior and a series of self-report questionnaires examining impulsivity, NSSI, and psychopathology. Four impulsivity dimensions (negative urgency, positive urgency, lack of premeditation, lack of perseverance) were associated with lifetime number of suicide attempts and/or suicide potential. Furthermore, results supported our hypotheses, as all but one relation was better accounted for by NSSI and, in the one exception, the direct effect was non-significant. Findings are consistent with the IPTS and suggest that suicidal behavior may not be a direct manifestation of impulsivity, but facilitated through exposure to PPEs capable of altering an individual׳s relationship to pain and fear of death. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Nonsuicidal self-injury: relationship to behavioral and self-rating measures of impulsivity and self-aggression.

PubMed

McCloskey, Michael S; Look, Amy E; Chen, Eunice Y; Pajoumand, Golnaz; Berman, Mitchell E

2012-04-01

Previous research using self-report measures has shown an association between nonsuicidal self-injurious behavior (NSSI) and impulsive tendencies. However, self-injurers have not been shown to be different from comparison groups on laboratory tasks putatively assessing impulsive behavior. One explanation for these contradictory findings is that self-report and laboratory measures of impulsive behavior tap into distinct but related constructs. Moreover, performance on laboratory measures of impulsive behavior can be influenced by myriad contextual and affective factors not present during past self-reported NSSI events. Accordingly, a relationship between behavioral tasks of impulsivity and self-injurious behavior could emerge if both are assessed relatively close in time under controlled laboratory conditions. To test this possibility, both self-ratings and laboratory task measures of self-injurious and impulsive behavior were employed in the current study. This multi-modal assessment approach revealed that self-rated impulsivity was associated with both self-report and behavioral measures of self-injurious behavior. Moreover, behavioral measures of impulsivity were associated with self-injurious behavior, but not NSSI history. These results provide support for the notion that a multi-modal approach to assessing self-injurious behavior is important for better understanding the correlates of nonsuicidal self-injury. © 2012 The American Association of Suicidology.

Impulsivity and hopelessness as predictors of suicide-related ideation among older adults.

PubMed

Neufeld, Eva; O'Rourke, Norm

2009-10-01

Research has demonstrated that impulsivity is strongly associated with suicide-related ideation and behaviour among young adults. However, to date, the potential importance of impulsivity as a predictor of suicide-related ideation in later life has yet to be determined. Our study examined impulsivity, hopelessness, depressive symptomatology, and sociodemographic factors vis-à-vis suicide-related ideation among older adults at risk of self-harm. A sample (n = 117) of older adults was recruited from multiple sources for this study over a 1-year period. Suicide-related ideation was measured with the Geriatric Suicide Ideation Scale, a multidimensional measure of suicide-related ideation developed for use with older adults. Canonical correlation identified 2 pairings of linear composites in which impulsivity emerged along both as significantly associated with facets of suicide-related ideation. Of note, the greater proportion of variance in impulsivity was subsumed along the second set of vectors with somatic depressive symptoms. Our findings suggest that the impulse to self-harm may be even more pronounced among older adults less likely to present as typically depressed. It is further suggested that impulsivity is more broadly associated with suicide-related ideation than hopelessness, and that screening for impulsivity as well as hopelessness may increase clinicians' ability to identify older adults at greatest risk of self-harm.

The independent effects of child sexual abuse and impulsivity on lifetime suicide attempts among female patients.

PubMed

Daray, Federico M; Rojas, Sasha M; Bridges, Ana J; Badour, Christal L; Grendas, Leandro; Rodante, Demián; Puppo, Soledad; Rebok, Federico

2016-08-01

Child sexual abuse (CSA) is a causal agent in many negative adulthood outcomes, including the risk for life-threatening behaviors such as suicide ideation and suicide attempts. Traumatic events such as CSA may pose risk in the healthy development of cognitive and emotional functioning during childhood. In fact, high impulsivity, a risk factor for suicidal behavior, is characteristic of CSA victims. The current study aims to understand the relations among CSA, impulsivity, and frequency of lifetime suicide attempts among a female patient sample admitted for suicidal behavior. Participants included 177 female patients between the ages of 18 and 63 years admitted at two hospitals in Buenos Aires, Argentina. Number of previous suicide attempts and CSA were assessed via structured interviews, while impulsivity was assessed with the Barratt Impulsiveness Scale (BIS-11). A model of structural equations was employed to evaluate the role of impulsivity in the relation between CSA and suicide attempts. CSA (β=.18, p<.05) and impulsivity (β=.24, p<.05) were associated with the number of previous suicide attempts. However, impulsivity was not significantly associated with CSA (β=.09, p>.05). CSA and impulsivity are independently associated with lifetime suicide attempts among female patients with recent suicidal behavior. Copyright © 2016 Elsevier Ltd. All rights reserved.

Impulsivity and clinical symptoms among adolescents with non-suicidal self-injury with or without attempted suicide.

PubMed

Dougherty, Donald M; Mathias, Charles W; Marsh-Richard, Dawn M; Prevette, Kristen N; Dawes, Michael A; Hatzis, Erin S; Palmes, Guy; Nouvion, Sylvain O

2009-08-30

This study examined clinical characteristics and laboratory-measured impulsive behavior of adolescents engaging in either non-suicidal self-injury with (NSSI+SA; n=25) or without (NSSI-Only; n=31) suicide attempts. We hypothesized that adolescent with NSSI+SI would exhibit more severe clinical symptoms and higher levels of behavioral impulsivity compared to adolescents with NSSI-Only. Adolescents were recruited from an inpatient psychiatric hospital unit and the two groups were compared on demographic characteristics, psychopathology, self-reported clinical ratings, methods of non-suicidal self-injury, and two laboratory impulsivity measures. Primary evaluations were conducted during psychiatric hospitalization, and a subset of those tested during hospitalization was retested 4-6 weeks after discharge. During hospitalization, NSSI+SA patients reported worse depression, hopelessness, and impulsivity on standard clinical measures, and demonstrated elevated impulsivity on a reward-directed laboratory measure compared to NSSI-Only patients. In the follow-up analyses, depression, hopelessness, suicidal ideation, and laboratory impulsivity were improved for both groups, but the NSSI+SA group still exhibited significantly more depressive symptoms, hopelessness, and impulsivity than the NSSI-Only group. Risk assessments for adolescents with NSSI+SA should include consideration not only of the severity of clinical symptoms but of the current level impulsivity as well.

Testing the relations between impulsivity-related traits, suicidality, and nonsuicidal self-injury: a test of the incremental validity of the UPPS model.

PubMed

Lynam, Donald R; Miller, Joshua D; Miller, Drew J; Bornovalova, Marina A; Lejuez, C W

2011-04-01

Borderline personality disorder (BPD) has received significant attention as a predictor of suicidal behavior (SB) and nonsuicidal self-injury (NSSI). Despite significant promise, trait impulsivity has received less attention. Understanding the relations between impulsivity and SB and NSSI is confounded, unfortunately, by the heterogeneous nature of impulsivity. This study examined the relations among 4 personality pathways to impulsive behavior studied via the UPPS model of impulsivity and SB and NSSI in a residential sample of drug abusers (N = 76). In this study, we tested whether these 4 impulsivity-related traits (i.e., Negative Urgency, Sensation Seeking, Lack of Premeditation, and Lack of Perseverance) provide incremental validity in the statistical prediction of SB and NSSI above and beyond BPD; they do. We also tested whether BPD symptoms provide incremental validity in the prediction of SB and NSSI above and beyond these impulsivity-related traits; they do not. In addition to the main effects of Lack of Premeditation and Negative Urgency, we found evidence of a robust interaction between these 2 personality traits. The current results argue strongly for the consideration of these 2 impulsivity-related domains--alone and in interaction--when attempting to understand and predict SB and NSSI.

Cognitive impulsivity and the development of delinquency from late childhood to early adulthood: Moderating effects of parenting behavior and peer relationships.

PubMed

Menting, Barbara; Van Lier, Pol A C; Koot, Hans M; Pardini, Dustin; Loeber, Rolf

2016-02-01

Cognitive impulsivity may increase children's risk of developing delinquent behavior. However, the influence of cognitive impulsivity may depend on social environmental risk factors. This study examined the moderating effect of late childhood parenting behaviors and peer relations on the influence of children's cognitive impulsivity on delinquency development across adolescence and early adulthood, while taking possible interactions with intelligence also into account. Delinquent behavior of 412 boys from the Pittsburgh Youth Study was measured annually from ages 13 to 29 years with official arrest records. Cognitive impulsivity (neurocognitive test scores) and intelligence were assessed at age 12-13. Parenting behaviors (persistence of discipline, positive reinforcement, and parental knowledge), peer delinquency, and peer conventional activities were assessed between ages 10 and 13 years. Results showed that, while controlling for intelligence, the influence of youths' cognitive impulsivity on delinquency depended on their parents' behaviors. An interaction was found among cognitive impulsivity, intelligence, and peer delinquency, but instead of cognitive impulsivity, the effect of intelligence on delinquency was particularly moderated. Overall, findings suggest that when there was moderation, high cognitive impulsivity and low intelligence were associated with an increased probability for engaging in delinquency predominantly among boys in a good social environment, but not in a poor social environment.

Mechanisms of impulsive choice: II. Time-based interventions to improve self-control

PubMed Central

Smith, Aaron P.; Marshall, Andrew T.; Kirkpatrick, Kimberly

2014-01-01

Impulsive choice behavior has been proposed as a primary risk factor for other maladaptive behaviors (e.g., gambling, substance abuse). Recent research has suggested that timing processes may play a key role in impulsive choice behavior, and could provide an avenue for altering impulsive choice. Accordingly, the current experiments assessed a set of time-based behavioral interventions to increase self-control while simultaneously assessing effects on timing processes within the impulsive choice task. Three experiments assessed temporal interventions using a differential reinforcement of low rates task (Experiment 1) and exposure to either a variable or fixed interval schedule (Experiments 2–3). The efficacy of the interventions was assessed in Sprague-Dawley (Experiments 1–2) and Lewis (Experiment 3) rat strains. Impulsive choice behavior was assessed by measuring preferences of a smaller-sooner (SS) versus a larger-later (LL) reward, while timing of the SS and LL durations was measured during peak trials within the impulsive choice procedure. The rats showed an increased preference for the LL following all three time-based interventions and also displayed increased temporal precision. These results add to the increasing evidence that supports a possible role for temporal processing in impulsive choice behavior and supply novel behavioral interventions to decrease impulsive behavior. PMID:25444771

Causal impulse response for circular sources in viscous media

PubMed Central

Kelly, James F.; McGough, Robert J.

2008-01-01

The causal impulse response of the velocity potential for the Stokes wave equation is derived for calculations of transient velocity potential fields generated by circular pistons in viscous media. The causal Green’s function is numerically verified using the material impulse response function approach. The causal, lossy impulse response for a baffled circular piston is then calculated within the near field and the far field regions using expressions previously derived for the fast near field method. Transient velocity potential fields in viscous media are computed with the causal, lossy impulse response and compared to results obtained with the lossless impulse response. The numerical error in the computed velocity potential field is quantitatively analyzed for a range of viscous relaxation times and piston radii. Results show that the largest errors are generated in locations near the piston face and for large relaxation times, and errors are relatively small otherwise. Unlike previous frequency-domain methods that require numerical inverse Fourier transforms for the evaluation of the lossy impulse response, the present approach calculates the lossy impulse response directly in the time domain. The results indicate that this causal impulse response is ideal for time-domain calculations that simultaneously account for diffraction and quadratic frequency-dependent attenuation in viscous media. PMID:18397018

Increased severity of suicidal behavior in impulsive aggressive patients exposed to familial adversities.

PubMed

Lopez-Castroman, J; Jaussent, I; Beziat, S; Guillaume, S; Baca-Garcia, E; Genty, C; Olié, E; Courtet, P

2014-10-01

The mechanisms by which childhood abuse and family history of suicidal behavior (FHS) lead to an increased risk of suicidal behavior are still unknown. Impulsive aggression may play an intermediate role. We investigated whether greater scores for aggression and impulsivity might be associated with the effects of FHS and/or childhood abuse on the severity of suicidal behavior. We examined the scores of three scales measuring impulsive aggression in a sample of 696 suicide attempters. We compared the highest and lowest scores with regard to reports of childhood abuse and FHS using adjusted multinomial regression models. Genetic polymorphisms of the serotonergic system known to be associated with impulsive aggression were also analyzed. Patients with high impulsive aggressive scores showed significant differences in sociodemographic, clinical and suicidal features compared with patients with low impulsive aggressive scores. Adjusted results showed that combinations of some types of childhood abuse and FHS, particularly emotional abuse and emotional neglect, are associated with high impulsivity and hostility scores. The SS genotype of the serotonin transporter gene (5-HTTLPR) was associated with high levels of impulsivity when the subjects reported emotional abuse [odds ratio (OR) 5.55, 95% confidence interval (CI) 1.75-17.5] or physical abuse (OR 5.03, 95% CI 1.50-16.9) in their childhood. Our results support the role of impulsive aggression as one of the links that may connect childhood abuse and FHS with severity of suicidal behavior.

Characteristics of individuals who make impulsive suicide attempts.

PubMed

Spokas, Megan; Wenzel, Amy; Brown, Gregory K; Beck, Aaron T

2012-02-01

Previous research has identified only a few variables that have been associated with making an impulsive suicide attempt. The aim of the current study was to compare individuals who made an impulsive suicide attempt with those who made a premeditated attempt on both previously examined and novel characteristics. Participants were classified as making an impulsive or premeditated attempt based on the Suicide Intent Scale (Beck et al., 1974a) and were compared on a number of characteristics relevant to suicidality, psychiatric history, and demographics. Individuals who made an impulsive attempt expected that their attempts would be less lethal; yet the actual lethality of both groups' attempts was similar. Those who made an impulsive attempt were less depressed and hopeless than those who made a premeditated attempt. Participants who made an impulsive attempt were less likely to report a history of childhood sexual abuse and more likely to be diagnosed with an alcohol use disorder than those who made a premeditated attempt. Although the sample size was adequate for bivariate statistics, future studies using larger sample sizes will allow for multivariate analyses of characteristics that differentiate individuals who make impulsive and premeditated attempts. Clinicians should not minimize the significance of impulsive attempts, as they are associated with a similar level of lethality as premeditated attempts. Focusing mainly on depression and hopelessness as indicators of suicide risk has the potential to under-identify those who are at risk for making impulsive attempts. Copyright © 2011 Elsevier B.V. All rights reserved.

Different relations between schedule-induced polydipsia and impulsive behaviour in the Spontaneously Hypertensive Rat and in high impulsive Wistar rats: questioning the role of impulsivity in adjunctive behaviour.

PubMed

Ibias, Javier; Pellón, Ricardo

2014-09-01

Rats belonging to three different strains (15 Wistar, 8 Spontaneously Hypertensive - SHR- and 8 Wistar Kyoto - WKY-) were used to evaluate the possible relationship between different levels of impulsivity and development of schedule-induced polydipsia (SIP). We first measured the rats' levels of impulsivity by means of delay-discounting and indifference-point procedures. Secondly, development of SIP was studied under a series of fixed time 15, 30, 60 and 120s food schedules, which were counterbalanced by means of a Latin-square design. Finally, we re-assessed the rats' levels of impulsivity by replicating the delay-discounting test. The findings showed that, starting from equivalent levels of impulsivity, development of SIP differed among the groups of rats. In comparison with the rest of the animals, the SHRs were observed to attain elevated drinking rates under SIP. On the other hand, the Wistar rats which had initial high impulsivity levels similar to those of the SHRs, displayed the lowest rates of induced drinking. Moreover, low levels of impulsivity in Wistar rats prior to SIP acquisition were reflected into high drinking rates. Relation of SIP and impulsivity is questioned by present results, which gives ground to the understanding of the behavioural mechanisms involved in adjunctive behaviour and its usefulness as an animal model of excessive behaviour. Copyright © 2014 Elsevier B.V. All rights reserved.

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

PubMed

Ding, Wei-na; Sun, Jin-hua; Sun, Ya-Wen; Chen, Xue; Zhou, Yan; Zhuang, Zhi-guo; Li, Lei; Zhang, Yong; Xu, Jian-rong; Du, Ya-song

2014-05-30

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

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

PubMed Central

2014-01-01

Background Recent studies suggest that Internet gaming addiction (IGA) is an impulse disorder, or is at least related to impulse control disorders. In the present study, we hypothesized that different facets of trait impulsivity may be specifically linked to the brain regions with impaired impulse inhibition function in IGA adolescents. Methods Seventeen adolescents with IGA and seventeen healthy controls were scanned during performance of a response-inhibition Go/No-Go task using a 3.0 T MRI scanner. The Barratt Impulsiveness Scale (BIS)-11 was used to assess impulsivity. Results There were no differences in the behavioral performance on the Go/No-Go task between the groups. However, the IGA group was significantly hyperactive during No-Go trials in the left superior medial frontal gyrus, right anterior cingulate cortex, right superior/middle frontal gyrus, left inferior parietal lobule, left precentral gyrus, and left precuneus and cuneus. Further, the bilateral middle temporal gyrus, bilateral inferior temporal gyrus, and right superior parietal lobule were significantly hypoactive during No-Go trials. Activation of the left superior medial frontal gyrus was positively associated with BIS-11 and Chen Internet Addiction Scale (CIAS) total score across IGA participants. Conclusions Our data suggest that the prefrontal cortex may be involved in the circuit modulating impulsivity, while its impaired function may relate to high impulsivity in adolescents with IGA, which may contribute directly to the Internet addiction process. PMID:24885073

Impulsivity and self-harm in adolescence: a systematic review.

PubMed

Lockwood, Joanna; Daley, David; Townsend, Ellen; Sayal, Kapil

2017-04-01

Research supports an association between impulsivity and self-harm, yet inconsistencies in methodology across studies have complicated understanding of this relationship. This systematic review examines the association between impulsivity and self-harm in community-based adolescents aged 11-25 years and aims to integrate findings according to differing concepts and methods. Electronic searches of EMBASE, MEDLINE, PsychINFO, CINAHL, PubMed and The Cochrane Library, and manual searches of reference lists of relevant reviews identified 4496 articles published up to July 2015, of which 28 met inclusion criteria. Twenty-four of the studies reported an association between broadly specified impulsivity and self-harm. However, findings varied according to the conception and measurement of impulsivity and the precision with which self-harm behaviours were specified. Specifically, lifetime non-suicidal self-injury was most consistently associated with mood-based impulsivity-related traits. However, cognitive facets of impulsivity (relating to difficulties maintaining focus or acting without forethought) differentiated current self-harm from past self-harm. These facets also distinguished those with thoughts of self-harm (ideation) from those who acted on thoughts (enaction). The findings suggested that mood-based impulsivity is related to the initiation of self-harm, while cognitive facets of impulsivity are associated with the maintenance of self-harm. In addition, behavioural impulsivity is most relevant to self-harm under conditions of negative affect. Collectively, the findings indicate that distinct impulsivity facets confer unique risks across the life-course of self-harm. From a clinical perspective, the review suggests that interventions focusing on reducing rash reactivity to emotions or improving self-regulation and decision making may offer most benefit in supporting those who self-harm.

Evaluation of factors that affect hip moment impulse during gait: A systematic review.

PubMed

Inai, Takuma; Takabayashi, Tomoya; Edama, Mutsuaki; Kubo, Masayoshi

2018-03-01

Decreasing the daily cumulative hip moments in the frontal and sagittal planes may lower the risk of hip osteoarthritis. Therefore, it may be important to evaluate factors that affect hip moment impulse during gait. It is unclear what factors affect hip moment impulse during gait. This systematic review aimed to evaluate different factors that affect hip moment impulse during gait in healthy adults and patients with hip osteoarthritis. Four databases (Scopus, ScienceDirect, PubMed, and PEDro) were searched up to August 2017 to identify studies that examined hip moment impulse during gait. Data extracted for analysis included the sample size, age, height, body mass, type of intervention, and main findings. After screening, 10 of the 975 studies identified were included in our analysis. Several factors, including a rocker bottom shoe, FitFlop™ sandals, ankle push-off, posture, stride length, body-weight unloading, a rollator, walking poles, and a knee brace, were reviewed. The main findings were as follows: increasing ankle push-off decreased both the hip flexion and extension moment impulses; body-weight unloading decreased both the hip extension and adduction moment impulses; the FitFlop™ sandal increased the sum of the hip flexion and extension moment impulses; long strides increased the hip extension moment impulse; and the use of a knee brace increased hip flexion moment impulse. Of note, none of the eligible studies included patients with hip osteoarthritis. The hip moment impulses can be modified by person-specific factors (ankle push-off and long strides) and external factors (body-weight unloading and use of the FitFlop™ sandals and a knee brace). Effects on the progression of hip osteoarthritis remain to be evaluated. Copyright © 2018 Elsevier B.V. All rights reserved.

Ventral striatal D2/3 receptor availability is associated with impulsive choice behavior as well aslimbic corticostriatal connectivity.

PubMed

Barlow, Rebecca L; Gorges, Martin; Wearn, Alfie; Niessen, Heiko G; Kassubek, Jan; Dalley, Jeffrey W; Pekcec, Anton

2018-03-15

Low dopamine D2/3 receptor availability in the nucleus accumbens (NAcb) shell is associated with highly-impulsive behavior in rats, as measured by premature responses in a cued attentional task. However, it is unclear whether dopamine D2/3 receptor availability in the NAcb is equally linked to intolerance for delayed rewards, a related form of impulsivity. We investigated the relationship between D2/3 receptor availability in the NAcb and impulsivity in a delay-discounting task (DDT) where animals must choose between immediate small-magnitude rewards and delayed larger-magnitude rewards. Corticostriatal D2/3 receptor availability was measured in rats stratified for high-, and low-impulsivity using in-vivo [18F]fallypride positron emission tomography (PET) and ex-vivo [3H]raclopride autoradiography. Resting-state functional connectivity in limbic corticostriatal networks was also assessed using fMRI. DDT impulsivity was inversely related to D2/3 receptor availability in the NAcb core but not the dorsal striatum with higher D2/3 binding in the NAcb shell of high-impulsive rats compared with low-impulsive rats. D2/3 receptor availability was associated with stronger connectivity between the cingulate cortex and hippocampus of high versus low impulsive rats. We conclude that DDT impulsivity is associated with low D2/3 receptor binding in the NAcb core. Thus two related forms of waiting impulsivity - premature responding and delay intolerance in a delay-of-reward task - implicate an involvement of D2/3 receptor availability in the NAcb shell and core, respectively. This dissociation may be causal or consequential to enhanced functional connectivity of limbic brain circuitry and hold relevance for attention-deficit/hyperactivity disorder, drug addiction and other psychiatric disorders.

Extreme sensory processing patterns show a complex association with depression, and impulsivity, alexithymia, and hopelessness.

PubMed

Serafini, Gianluca; Gonda, Xenia; Canepa, Giovanna; Pompili, Maurizio; Rihmer, Zoltan; Amore, Mario; Engel-Yeger, Batya

2017-03-01

The involvement of extreme sensory processing patterns, impulsivity, alexithymia, and hopelessness was hypothesized to contribute to the complex pathophysiology of major depression and bipolar disorder. However, the nature of the relation between these variables has not been thoroughly investigated. This study aimed to explore the association between extreme sensory processing patterns, impulsivity, alexithymia, depression, and hopelessness. We recruited 281 euthymic participants (mean age=47.4±12.1) of which 62.3% with unipolar major depression and 37.7% with bipolar disorder. All participants completed the Adolescent/Adult Sensory Profile (AASP), Toronto Alexithymia Scale (TAS-20), second version of the Beck Depression Inventory (BDI-II), Barratt Impulsivity Scale (BIS), and Beck Hopelessness Scale (BHS). Lower registration of sensory input showed a significant correlation with depression, impulsivity, attentional/motor impulsivity, and alexithymia. It was significantly more frequent among participants with elevated hopelessness, and accounted for 22% of the variance in depression severity, 15% in greater impulsivity, 36% in alexithymia, and 3% in hopelessness. Elevated sensory seeking correlated with enhanced motor impulsivity and decreased non-planning impulsivity. Higher sensory sensitivity and sensory avoiding correlated with depression, impulsivity, and alexithymia. The study was limited by the relatively small sample size and cross-sectional nature of the study. Furthermore, only self-report measures that may be potentially biased by social desirability were used. Extreme sensory processing patterns, impulsivity, alexithymia, depression, and hopelessness may show a characteristic pattern in patients with major affective disorders. The careful assessment of sensory profiles may help in developing targeted interventions and improve functional/adaptive strategies. Copyright © 2016 Elsevier B.V. All rights reserved.

Pharmacologic dissociation between impulsivity and alcohol drinking in High Alcohol Preferring mice

PubMed Central

Oberlin, Brandon G.; Bristow, R. Evan; Heighton, Meredith E.; Grahame, Nicholas J.

2014-01-01

Background Impulsivity is genetically correlated with, and precedes addictive behaviors and alcoholism. If impulsivity or attention is causally related to addiction, certain pharmacological manipulations of impulsivity and/or attention may affect alcohol drinking, and vice versa. The current studies were designed to explore the relationship among impulsivity, drinking, and vigilance in selectively bred High Alcohol Preferring (HAP) mice, a line that has previously demonstrated both high impulsivity and high alcohol consumption. Amphetamine, naltrexone and memantine were tested in a delay discounting (DD) task for their effects on impulsivity and vigilance. The same drugs and doses were also assessed for effects on alcohol drinking in a two-bottle choice test. Methods HAP mice were subjected to a modified version of adjusting amount DD using 0.5 sec and 10 sec delays to detect decreases and increases, respectively, in impulsive responding. In 2 experiments, mice were given amphetamine (0.4, 0.8 or 1.2 mg/kg), naltrexone (3 and 10 mg/kg), and memantine (1 and 5 mg/kg) before DD testing. Another pair of studies used scheduled access, two-bottle choice drinking to assess effects of amphetamine (0.4, 1.2, or 3.0 mg/kg), naltrexone (3 and 10 mg/kg), and memantine (1 and 5 mg/kg) on alcohol consumption. Results Amphetamine dose-dependently reduced impulsivity and vigilance decrement in DD, but similar doses left alcohol drinking unaffected. Naltrexone and memantine decreased alcohol intake at doses that did not affect water drinking, but had no effects on impulsivity or vigilance decrement in the DD task. Conclusions Contrary to our hypothesis, none of the drugs tested here, while effective either on alcohol drinking or impulsivity, decreased both behaviors. These findings suggest that the genetic association between drinking and impulsivity observed in this population is mediated by mechanisms other than those targeted by the drugs tested in these studies. PMID:20491739

The development of a brief self-report questionnaire to measure 'recent' rash impulsivity: a preliminary investigation of its validity and association with recent alcohol consumption.

PubMed

Mayhew, Matthew J; Powell, Jane H

2014-11-01

Traditionally, impulsivity has been regarded as a stable trait. However, a series of longitudinal and behavioural laboratory studies has found that impulsivity can fluctuate within individuals, suggesting that it has a state as well as a trait manifestation. Whilst existing impulsivity questionnaires tap the former, there is no self-report instrument to assess recent fluctuations in impulsivity. Research aims and design The present study set out to develop and undertake preliminary validation of a measure of 'recent' impulsivity, focusing in particular on Rash Impulsivity. Part of the construct validation of the resulting Recent Rash Impulsivity Scale (RRIS) entailed examining its association with recent alcohol intake, since there are well-documented reciprocal relationships between alcohol consumption and inhibitory control. In developing the RRIS, items from existing trait impulsivity questionnaires were converted into a 'previous two weeks' format. The pilot RRIS was then administered, along with a parallel trait version (Trait Rash Impulsivity Scale; TRIS) and a well-established trait impulsivity measure (the BIS-11; Patton, Stanford & Barratt, 1995), to two cohorts of first-year undergraduates aged 17 to 25 (N=240), on two occasions one month apart. Information about habitual and recent alcohol intake was also gathered. Factor analyses on both the RRIS and TRIS identified two factors: 'Cognitive Impulsivity' (CogImp) and 'Motor Impulsivity' (MotImp). Consistent with the RRIS being sensitive to fluctuations in impulsivity, it was found that, as predicted: i) the RRIS was somewhat less strongly correlated than the TRIS with an established trait measure (the BIS-11; Patton et al., 1995); ii) the test-retest stability of 'Total' scores (CogImp and MotImp) was weaker for the RRIS than the TRIS; iii) there was evidence that the RRIS MotImp and Total scales were more strongly predicted by recent alcohol intake than were their trait equivalents; and iv) the RRIS CogImp and Total scales correlated more strongly with their trait equivalents in participants whose alcohol consumption had remained stable recently (relative to their habitual intake), compared to those whose consumption had recently changed. These data suggest that transient changes in impulsivity can be assessed via self-report, and that the RRIS is sensitive to recent changes in alcohol intake. Subject to a more intensive and detailed validation, it is thus promising as a tool for tapping and characterising fluctuations in behavioural control and for exploring a range of factors to which this might be associated. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

ERIC Educational Resources Information Center

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

2004-01-01

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

Cryogenic liquid resettlement activated by impulsive thrust in space-based propulsion system

NASA Technical Reports Server (NTRS)

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

1991-01-01

The purpose of present study is to investigate most efficient technique for propellant resettling through the minimization of propellant usage and weight penalties. Comparison between the constant reverse gravity acceleration and impulsive reverse gravity acceleration to be used for the activation of propellant resettlement, it shows that impulsive reverse gravity thrust is superior to constant reverse gravity thrust for liquid reorientation in a reduced gravity environment. Comparison among impulsive reverse gravity thrust with 0.1, 1.0 and 10 Hz frequencies for liquid filled level in the range between 30 to 80 percent, it shows that the selection of 1.0 Hz frequency impulsive thrust over the other frequency ranges of impulsive thrust is most proper based on the present study.

Cryogenic liquid resettlement activated by impulsive thrust in space-based propulsion system

NASA Technical Reports Server (NTRS)

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

1991-01-01

The purpose of present study is to investigate the most efficient technique for propellant resettling through the minimization of propellant usage and weight penalties. Comparison between the constant reverse gravity acceleration and impulsive reverse gravity acceleration to be used for the activation of propellant resettlement shows that impulsive reverse gravity thrust is superior to constant reverse gravity thrust for liquid reorientation in a reduced gravity environment. Comparison among impulsive reverse gravity thrust with 0.1, 1.0, and 10 Hz frequencies for liquid-filled level in the range between 30 to 80 percent shows that the selection of a medium frequency of 1.0 Hz impulsive thrust over the other frequency ranges of impulsive thrust is the most proper.

The horizontal computerized rotational impulse test.

PubMed

Furman, Joseph M; Shirey, Ian; Roxberg, Jillyn; Kiderman, Alexander

2016-01-01

Whole-body impulsive rotations were used to overcome several limitations associated with manual head impulse testing. A computer-controlled rotational chair delivered brief, whole-body, earth-vertical axis yaw impulsive rotations while eye movements were measured using video-oculography. Results from an unselected group of 20 patients with dizziness and a group of 22 control subjects indicated that the horizontal computerized rotational head impulse test (crHIT) is well-tolerated and provides an estimate of unidirectional vestibulo-ocular reflex gain comparable to results from caloric testing. This study demonstrates that the horizontal crHIT is a new assessment tool that overcomes many of the limitations of manual head impulse testing and provides a reliable laboratory-based measure of unilateral horizontal semicircular canal function.

Closed-Form and Numerically-Stable Solutions to Problems Related to the Optimal Two-Impulse Transfer Between Specified Terminal States of Keplerian Orbits

NASA Technical Reports Server (NTRS)

Senent, Juan

2011-01-01

The first part of the paper presents some closed-form solutions to the optimal two-impulse transfer between fixed position and velocity vectors on Keplerian orbits when some constraints are imposed on the magnitude of the initial and final impulses. Additionally, a numerically-stable gradient-free algorithm with guaranteed convergence is presented for the minimum delta-v two-impulse transfer. In the second part of the paper, cooperative bargaining theory is used to solve some two-impulse transfer problems when the initial and final impulses are carried by different vehicles or when the goal is to minimize the delta-v and the time-of-flight at the same time.

Factorization breaking of A d T for polarized deuteron targets in a relativistic framework

DOE PAGES

Jeschonnek, Sabine; Van Orden, J. W.

2017-04-17

We discuss the possible factorization of the tensor asymmetrymore » $$A^T_d$$ measured for polarized deuteron targets within a relativistic framework. We define a reduced asymmetry and find that factorization holds only in plane wave impulse approximation and if $p$-waves are neglected. Our numerical results show a strong factorization breaking once final state interactions are included. We also compare the $d$-wave content of the wave functions with the size of the factored, reduced asymmetry and find that there is no systematic relationship of this quantity to the d-wave probability of the various wave functions.« less

Flutter and forced response of mistuned rotors using standing wave analysis

NASA Technical Reports Server (NTRS)

Dugundji, J.; Bundas, D. J.

1983-01-01

A standing wave approach is applied to the analysis of the flutter and forced response of tuned and mistuned rotors. The traditional traveling wave cascade airforces are recast into standing wave arbitrary motion form using Pade approximants, and the resulting equations of motion are written in the matrix form. Applications for vibration modes, flutter, and forced response are discussed. It is noted that the standing wave methods may prove to be more versatile for dealing with certain applications, such as coupling flutter with forced response and dynamic shaft problems, transient impulses on the rotor, low-order engine excitation, bearing motions, and mistuning effects in rotors.

Flutter and forced response of mistuned rotors using standing wave analysis

NASA Technical Reports Server (NTRS)

Bundas, D. J.; Dungundji, J.

1983-01-01

A standing wave approach is applied to the analysis of the flutter and forced response of tuned and mistuned rotors. The traditional traveling wave cascade airforces are recast into standing wave arbitrary motion form using Pade approximants, and the resulting equations of motion are written in the matrix form. Applications for vibration modes, flutter, and forced response are discussed. It is noted that the standing wave methods may prove to be more versatile for dealing with certain applications, such as coupling flutter with forced response and dynamic shaft problems, transient impulses on the rotor, low-order engine excitation, bearing motion, and mistuning effects in rotors.

Experimental Study of Exclusive H2(e,e'p)n Reaction Mechanisms at High Q2

NASA Astrophysics Data System (ADS)

Egiyan, K. S.; Asryan, G.; Gevorgyan, N.; Griffioen, K. A.; Laget, J. M.; Kuhn, S. E.; Adams, G.; Amaryan, M. J.; Ambrozewicz, P.; Anghinolfi, M.; Audit, G.; Avakian, H.; Bagdasaryan, H.; Baillie, N.; Ball, J. P.; Baltzell, N. A.; Barrow, S.; Batourine, V.; Battaglieri, M.; Bedlinskiy, I.; Bektasoglu, M.; Bellis, M.; Benmouna, N.; Berman, B. L.; Biselli, A. S.; Blaszczyk, L.; Bouchigny, S.; Boiarinov, S.; Bradford, R.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Bültmann, S.; Burkert, V. D.; Butuceanu, C.; Calarco, J. R.; Careccia, S. L.; Carman, D. S.; Cazes, A.; Chen, S.; Cole, P. L.; Collins, P.; Coltharp, P.; Cords, D.; Corvisiero, P.; Crabb, D.; Crede, V.; Cummings, J. P.; Dashyan, N.; de Masi, R.; de Vita, R.; de Sanctis, E.; Degtyarenko, P. V.; Denizli, H.; Dennis, L.; Deur, A.; Dharmawardane, K. V.; Dickson, R.; Djalali, C.; Dodge, G. E.; Donnelly, J.; Doughty, D.; Dugger, M.; Dytman, S.; Dzyubak, O. P.; Egiyan, H.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fatemi, R.; Fedotov, G.; Feldman, G.; Feuerbach, R. J.; Fersch, R.; Garçon, M.; Gavalian, G.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gonenc, A.; Gordon, C. I. O.; Gothe, R. W.; Guidal, M.; Guillo, M.; Guler, N.; Guo, L.; Gyurjyan, V.; Hadjidakis, C.; Hafidi, K.; Hakobyan, H.; Hakobyan, R. S.; Hanretty, C.; Hardie, J.; Hersman, F. W.; Hicks, K.; Hleiqawi, I.; Holtrop, M.; Hyde-Wright, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Ito, M. M.; Jenkins, D.; Jo, H. S.; Joo, K.; Juengst, H. G.; Kalantarians, N.; Kellie, J. D.; Khandaker, M.; Kim, W.; Klein, A.; Klein, F. J.; Klimenko, A. V.; Kossov, M.; Krahn, Z.; Kramer, L. H.; Kubarovsky, V.; Kuhn, J.; Kuleshov, S. V.; Lachniet, J.; Langheinrich, J.; Lawrence, D.; Li, Ji; Livingston, K.; Lu, H. Y.; MacCormick, M.; Marchand, C.; Markov, N.; Mattione, P.; McAleer, S.; McKinnon, B.; McNabb, J. W. C.; Mecking, B. A.; Mehrabyan, S.; Melone, J. J.; Mestayer, M. D.; Meyer, C. A.; Mibe, T.; Mikhailov, K.; Minehart, R.; Mirazita, M.; Miskimen, R.; Mokeev, V.; Moriya, K.; Morrow, S. A.; Moteabbed, M.; Mueller, J.; Munevar, E.; Mutchler, G. S.; Nadel-Turonski, P.; Nasseripour, R.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Niczyporuk, B. B.; Niroula, M. R.; Niyazov, R. A.; Nozar, M.; O'Rielly, G. V.; Osipenko, M.; Ostrovidov, A. I.; Park, K.; Pasyuk, E.; Paterson, C.; Anefalos Pereira, S.; Pierce, J.; Pivnyuk, N.; Pocanic, D.; Pogorelko, O.; Pozdniakov, S.; Preedom, B. M.; Price, J. W.; Prok, Y.; Protopopescu, D.; Raue, B. A.; Riccardi, G.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Ronchetti, F.; Rosner, G.; Rossi, P.; Sabatié, F.; Salamanca, J.; Salgado, C.; Santoro, J. P.; Sapunenko, V.; Schumacher, R. A.; Serov, V. S.; Sharabian, Y. G.; Shvedunov, N. V.; Skabelin, A. V.; Smith, E. S.; Smith, L. C.; Sober, D. I.; Sokhan, D.; Stavinsky, A.; Stepanyan, S. S.; Stepanyan, S.; Stokes, B. E.; Stoler, P.; Strauch, S.; Taiuti, M.; Tedeschi, D. J.; Thoma, U.; Tkabladze, A.; Tkachenko, S.; Todor, L.; Tur, C.; Ungaro, M.; Vineyard, M. F.; Vlassov, A. V.; Watts, D. P.; Weinstein, L. B.; Weygand, D. P.; Williams, M.; Wolin, E.; Wood, M. H.; Yegneswaran, A.; Zana, L.; Zhang, J.; Zhao, B.; Zhao, Z. W.

2007-06-01

The reaction H2(e,e'p)n has been studied with full kinematic coverage for photon virtuality 1.75

Accuracy Improvement in Magnetic Field Modeling for an Axisymmetric Electromagnet

NASA Technical Reports Server (NTRS)

Ilin, Andrew V.; Chang-Diaz, Franklin R.; Gurieva, Yana L.; Il,in, Valery P.

2000-01-01

This paper examines the accuracy and calculation speed for the magnetic field computation in an axisymmetric electromagnet. Different numerical techniques, based on an adaptive nonuniform grid, high order finite difference approximations, and semi-analitical calculation of boundary conditions are considered. These techniques are being applied to the modeling of the Variable Specific Impulse Magnetoplasma Rocket. For high-accuracy calculations, a fourth-order scheme offers dramatic advantages over a second order scheme. For complex physical configurations of interest in plasma propulsion, a second-order scheme with nonuniform mesh gives the best results. Also, the relative advantages of various methods are described when the speed of computation is an important consideration.

Apollo 16, LM-11 descent propulsion system final flight evaluation

NASA Technical Reports Server (NTRS)

Avvenire, A. T.

1974-01-01

The performance of the LM-11 descent propulsion system during the Apollo 16 missions was evaluated and found satisfactory. The average engine effective specific impulse was 0.1 second higher than predicted, but well within the predicted one sigma uncertainty of 0.2 seconds. Several flight measurement discrepancies existed during the flight as follows: (1) the chamber pressure transducer had a noticeable drift, exhibiting a maximum error of about 1.5 psi at approximately 130 seconds after engine ignition, (2) the fuel and oxidizer interface pressure measurements appeared to be low during the entire flight, and (3) the fuel propellant quantity gaging system did not perform within expected accuracies.

A preliminary assessment of the impact of 2-D exhaust-nozzle geometry on the cruise range of a hypersonic aircraft with top-mounted ramjet propulsion

NASA Technical Reports Server (NTRS)

Vahl, W. A.; Weidner, J. P.

1980-01-01

A theoretical study of full length and shortened, two dimensional, isentropic, exhaust nozzles integrated with top mounted ramjet propulsion nacelles were conducted. Both symmetric and asymmetric contoured nozzles with a range of angular orientations were considered. Performance comparisons to determine optimum installations for a representative hypersonic vehicle at Mach 5 cruise conditions are presented on the basis of cruise range, propulsive specific impulse, inlet area requirements, and overall lift drag ratio. The effect of approximating the nozzle internal contours with planar surfaces and the determination of viscous and frozen flow effects are also presented.

Performance effects resulting from plugged liquid oxygen posts of the Space Shuttle Main Engine Injector

NASA Technical Reports Server (NTRS)

Kim, S.; Trinh, H. P.

1992-01-01

The paper discusses the performance effects resulting from plugged LOX posts of the Space Shuttle Main Engine Injector. The simulation was performed with the REFLEQS 2-D code. Analysis was performed axisymmetrically and injector surface was divided into several regions to account for the mixture ratio variation on the injector surface. The reduction of vaccum specific impulse was approximately 0.01 second per plugged LOX post. This reduction is an order of magnitude higher than the result of Space Shuttle flight reconstruction data. It is presumed that this overprediction is due to the axisymmetric simulation that smears local effects.

Dynamical evolution of globular-cluster systems in clusters of galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muzzio, J.C.

1987-04-01

The dynamical processes that affect globular-cluster systems in clusters of galaxies are analyzed. Two-body and impulsive approximations are utilized to study dynamical friction, drag force, tidal stripping, tidal radii, globular-cluster swapping, tidal accretion, and galactic cannibalism. The evolution of galaxies and the collision of galaxies are simulated numerically; the steps involved in the simulation are described. The simulated data are compared with observations. Consideration is given to the number of galaxies, halo extension, location of the galaxies, distribution of the missing mass, nonequilibrium initial conditions, mass dependence, massive central galaxies, globular-cluster distribution, and lost globular clusters. 116 references.

Bifurcations and chaos in a parametrically damped two-well Duffing oscillator subjected to symmetric periodic pulses.

PubMed

Chacón, R; Martínez García-Hoz, A

1999-06-01

We study a parametrically damped two-well Duffing oscillator, subjected to a periodic string of symmetric pulses. The order-chaos threshold when altering solely the width of the pulses is investigated theoretically through Melnikov analysis. We show analytically and numerically that most of the results appear independent of the particular wave form of the pulses provided that the transmitted impulse is the same. By using this property, the stability boundaries of the stationary solutions are determined to first approximation by means of an elliptic harmonic balance method. Finally, the bifurcation behavior at the stability boundaries is determined numerically.

Performance of 10-kW class xenon ion thrusters

NASA Technical Reports Server (NTRS)

Patterson, Michael J.; Rawlin, Vincent K.

1988-01-01

Presented are performance data for laboratory and engineering model 30 cm-diameter ion thrusters operated with xenon propellant over a range of input power levels from approximately 2 to 20 kW. Also presented are preliminary performance results obtained from laboratory model 50 cm-diameter cusp- and divergent-field ion thrusters operating with both 30 cm- amd 50 cm-diameter ion optics up to a 20 kW input power. These data include values of discharge chamber propellant and power efficiencies, as well as values of specific impulse, thruster efficiency, thrust and power. The operation of the 30 cm- and 50 cm-diameter ion optics are also discussed.

Multiple Scattering Effects on Pulse Propagation in Optically Turbid Media.

NASA Astrophysics Data System (ADS)

Joelson, Bradley David

The effects of multiple scattering in a optically turbid media is examined for an impulse solution to the radiative transfer equation for a variety of geometries and phase functions. In regions where the complexities of the phase function proved too cumbersome for analytic methods Monte Carlo techniques were developed to describe the entire scalar radiance distribution. The determination of a general spread function is strongly dependent on geometry and particular regions where limits can be placed on the variables of the problem. Hence, the general spread function is first simplified by considering optical regions which reduce the complexity of the variable dependence. First, in the small-angle limit we calculate some contracted spread functions along with their moments and then use Monte Carlo techniques to establish the limitations imposed by the small-angle approximation in planar geometry. The point spread function (PSF) for a spherical geometry is calculated for the full angular spread in the forward direction of ocean waters using Monte Carlo methods in the optically thin and moderate depths and analytic methods in the diffusion domain. The angular dependence of the PSF for various ocean waters is examined for a range of optical parameters. The analytic method used in the diffusion calculation is justified by examining the angular dependence of the radiance of a impulse solution in a planar geometry for a prolongated Henyey-Greenstein phase function of asymmetry factor approximately equal to that of the ocean phase functions. The Legendre moments of the radiance are examined in order to examine the viability of the diffusion approximation which assumes a linearly anisotropic angular distribution for the radiance. A realistic lidar calculation is performed for a variety of ocean waters to determine the effects of multiple scattering on the determination of the speed of sound by using the range gated frequency spectrum of the lidar signal. It is shown that the optical properties of the ocean help to ensure single scatter form for the frequency spectra of the lidar signal. This spectra can then be used to compute the speed of sound and backscatter probability.

Relationships between trait impulsivity and cognitive control: the effect of attention switching on response inhibition and conflict resolution.

PubMed

Leshem, Rotem

2016-02-01

This study examined the relationship between trait impulsivity and cognitive control, as measured by the Barratt Impulsiveness Scale (BIS) and a focused attention dichotic listening to words task, respectively. In the task, attention was manipulated in two attention conditions differing in their cognitive control demands: one in which attention was directed to one ear at a time for a whole block of trials (blocked condition) and another in which attention was switched pseudo-randomly between the two ears from trial to trial (mixed condition). Results showed that high impulsivity participants exhibited more false alarm and intrusion errors as well as a lesser ability to distinguish between stimuli in the mixed condition, as compared to low impulsivity participants. In the blocked condition, the performance levels of the two groups were comparable with respect to these measures. In addition, total BIS scores were correlated with intrusions and laterality index in the mixed but not the blocked condition. The findings suggest that high impulsivity individuals may be less prone to attentional difficulties when cognitive load is relatively low. In contrast, when attention switching is involved, high impulsivity is associated with greater difficulty in inhibiting responses and resolving cognitive conflict than is low impulsivity, as reflected in error-prone information processing. The conclusion is that trait impulsivity in a non-clinical population is manifested more strongly when attention switching is required than during maintained attention. This may have important implications for the conceptualization and treatment of impulsivity in both non-clinical and clinical populations.

Differential effects of the pharmacological stressor yohimbine on impulsive decision making and response inhibition.

PubMed

Schippers, M C; Schetters, D; De Vries, T J; Pattij, T

2016-07-01

High levels of impulsivity have been associated with psychiatric disorders such as attention-deficit/hyperactivity disorder (ADHD) and substance abuse. In addition, acute stress is known to exacerbate many psychiatric symptoms in impulse control disorders. The purpose of the current study was to investigate the acute effects of the pharmacological stressor yohimbine on response inhibition and impulsive choice. A group of male rats (n = 12) was trained in the delayed reward task (DRT) to assess impulsive choice. A separate group (n = 10) was trained in the stop-signal task (SST) to measure response inhibition. Upon stable responding, the effects of yohimbine (0, 1.25, 2.5, and 5 mg/kg i.p.) were tested in a Latin square design. Acute yohimbine significantly increased the preference for the large and delayed reinforcer in the DRT, indicating a decrease in impulsive choice. On the contrary, the effect size of 1.25 mg/kg yohimbine on stop-signal reaction times correlated negatively with baseline performance, suggesting a baseline-dependent effect on response inhibition as measured in the SST. The current data suggest that the effects of the pharmacological stressor yohimbine on impulse control strongly depend on the type of impulsive behavior. Pharmacological stress decreased impulsive decision making, an observation that is in line with previously published rodent studies. By contrast, the lowest dose of yohimbine revealed a baseline-dependent effect on response inhibition. As such, the effects of yohimbine are largely comparable to the effects of psychostimulants on impulsivity and may support the notion of cross sensitization of stress and psychostimulants.

The effects of oral d-amphetamine on impulsivity in smoked and intranasal cocaine users.

PubMed

Reed, Stephanie Collins; Evans, Suzette M

2016-06-01

Effective treatments for cocaine use disorders remain elusive. Two factors that may be related to treatment failures are route of cocaine used and impulsivity. Smoked cocaine users are more likely to have poorer treatment outcomes compared to intranasal cocaine users. Further, cocaine users are impulsive and impulsivity is associated with poor treatment outcomes. While stimulants are used to treat Attention Deficit Hyperactivity Disorder (ADHD) and attenuate certain cocaine-related behaviors, few studies have comprehensively examined whether stimulants can reduce behavioral impulsivity in cocaine users, and none examined route of cocaine use as a factor. The effects of immediate release oral d-amphetamine (AMPH) were examined in 34 cocaine users (13 intranasal, 21 smoked). Participants had three separate sessions where they were administered AMPH (0, 10, or 20mg) and completed behavioral measures of impulsivity and risk-taking and subjective measures of abuse liability. Smoked cocaine users were more impulsive on the Delayed Memory Task, the GoStop task and the Delay Discounting Task than intranasal cocaine users. Smoked cocaine users also reported more cocaine craving and negative mood than intranasal cocaine users. AMPH produced minimal increases on measures of abuse liability (e.g., Drug Liking). Smoked cocaine users were more impulsive than intranasal cocaine users on measures of impulsivity that had a delay component. Additionally, although AMPH failed to attenuate impulsive responding, there was minimal evidence of abuse liability in cocaine users. These preliminary findings need to be confirmed in larger samples that control for route and duration of cocaine use. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The Effects of Oral d-Amphetamine on Impulsivity in Smoked and Intranasal Cocaine Users

PubMed Central

Reed, Stephanie Collins; Evans, Suzette M.

2016-01-01

BACKGROUND Effective treatments for cocaine use disorders remain elusive. Two factors that may be related to treatment failures are route of cocaine used and impulsivity. Smoked cocaine users are more likely to have poorer treatment outcomes compared to intranasal cocaine users. Further, cocaine users are impulsive and impulsivity is associated with poor treatment outcomes. While stimulants are used to treat Attention Deficit Hyperactivity Disorder (ADHD) and attenuate certain cocaine-related behaviors, few studies have comprehensively examined whether stimulants can reduce behavioral impulsivity in cocaine users, and none examined route of cocaine use as a factor. METHODS The effects of immediate release oral d-amphetamine (AMPH) were examined in 34 cocaine users (13 intranasal, 21 smoked). Participants had three separate sessions where they were administered AMPH (0, 10, or 20 mg) and completed behavioral measures of impulsivity and risk-taking and subjective measures of abuse liability. RESULTS Smoked cocaine users were more impulsive on the Delayed Memory Task, the GoStop task and the Delay Discounting Task than intranasal cocaine users. Smoked cocaine users also reported more cocaine craving and negative mood than intranasal cocaine users. AMPH produced minimal increases on measures of abuse liability (e.g., Drug Liking). CONCLUSIONS Smoked cocaine users were more impulsive than intranasal cocaine users on measures of impulsivity that had a delay component. Additionally, although AMPH failed to attenuate impulsive responding, there was minimal evidence of abuse liability in cocaine users. These preliminary findings need to be confirmed in larger samples that control for route and duration of cocaine use. PMID:27114203

Differential effects of social and novelty enrichment on individual differences in impulsivity and behavioral flexibility.

PubMed

Wang, Maya Zhe; Marshall, Andrew T; Kirkpatrick, Kimberly

2017-06-01

Early life experience profoundly impacts behavior and cognitive functions in rats. The present study investigated how the presence of conspecifics and/or novel objects, could independently influence individual differences in impulsivity and behavioral flexibility. Twenty-four rats were reared in an isolated condition, an isolated condition with a novel object, a pair-housed social condition, or a pair-housed social condition with a novel object. The rats were then tested on an impulsive choice task, a behavioral flexibility task, and an impulsive action task. Novelty enrichment produced an overall increase in impulsive choice, while social enrichment decreased impulsive choice in the absence of novelty enrichment and also produced an overall increase in impulsive action. In the behavioral flexibility task, social enrichment increased regressive errors, whereas both social and novelty enrichment reduced never-reinforced errors. Individual differences analyses indicated a significant relationship between performance in the behavioral flexibility and impulsive action tasks, which may reflect a common psychological correlate of action inhibition. Moreover, there was a relationship between delay sensitivity in the impulsive choice task and performance on the DRL and behavioral flexibility tasks, suggesting a dual role for timing and inhibitory processes in driving the interrelationship between these tasks. Overall, these results indicate that social and novelty enrichment produce distinct effects on impulsivity and adaptability, suggesting the need to parse out the different elements of enrichment in future studies. Further research is warranted to better understand how individual differences in sensitivity to enrichment affect individuals' interactions with and the resulting consequences of the rearing environment. Copyright © 2017 Elsevier B.V. All rights reserved.

Differential effects of social and novelty enrichment on individual differences in impulsivity and behavioral flexibility

PubMed Central

Wang, Maya Zhe; Marshall, Andrew T.; Kirkpatrick, Kimberly

2017-01-01

Early life experience profoundly impacts behavior and cognitive functions in rats. The present study investigated how the presence of conspecifics and/or novel objects, could independently influence individual differences in impulsivity and behavioral flexibility. Twenty-four rats were reared in an isolated condition, an isolated condition with a novel object, a pair-housed social condition, or a pair-housed social condition with a novel object. The rats were then tested on an impulsive choice task, a behavioral flexibility task, and an impulsive action task. Novelty enrichment produced an overall increase in impulsive choice, while social enrichment decreased impulsive choice in the absence of novelty enrichment and also produced an overall increase in impulsive action. In the behavioral flexibility task, social enrichment increased regressive errors, whereas both social and novelty enrichment reduced never reinforced errors. Individual differences analyses indicated a significant relationship between performance in the behavioral flexibility and impulsive action tasks, which may reflect a common psychological correlate of action inhibition. Moreover, there was a relationship between delay sensitivity in the impulsive choice task and performance on the DRL and behavioral flexibility tasks, suggesting a dual role for timing and inhibitory processes in driving the interrelationship between these tasks. Overall, these results indicate that social and novelty enrichment produce distinct effects on impulsivity and adaptability, suggesting the need to parse out the different elements of enrichment in future studies. Further research is warranted to better understand how individual differences in sensitivity to enrichment affect individuals’ interactions with and the resulting consequences of the rearing environment. PMID:28341610

Norepinephrine and impulsivity: Effects of acute yohimbine

PubMed Central

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

2013-01-01

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 twenty-three 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; 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. PMID:23559222

The relationship of impulsivity and cortical thickness in depressed and non-depressed adolescents.

PubMed

Fradkin, Yuli; Khadka, Sabin; Bessette, Katie L; Stevens, Michael C

2017-10-01

Major Depressive Disorder (MDD) is recognized to be heterogeneous in terms of brain structure abnormality findings across studies, which might reflect previously unstudied traits that confer variability to neuroimaging measurements. The purpose of this study was to examine the relationships between different types of trait impulsivity and MDD diagnosis on adolescent brain structure. We predicted that adolescents with depression who were high on trait impulsivity would have more abnormal cortical structure than depressed patients or non-MDD who were low on impulsivity. We recruited 58 subjects, including 29 adolescents (ages 12-19) with a primary DSM-IV diagnosis of MDD and a history of suicide attempt and 29 demographically-matched healthy control participants. Our GLM-based analyses sought to describe differences in the linear relationships between cortical thickness and impulsivity trait levels. As hypothesized, we found significant moderation effects in rostral middle frontal gyrus and right paracentral lobule cortical thickness for different subscales of the Barratt Impulsiveness Scale. However, although these brain-behavior relationships differed between diagnostic study groups, they were not simple additive effects as we had predicted. For the middle frontal gyrus, non-MDD participants showed a strong positive association between cortical thickness and BIS-11 Motor scores, while MDD-diagnosed participants showed a negative association. For Non-Planning Impulsiveness, paracentral lobule cortical thickness was observed with greater impulsivity in MDD, but no association was found for controls. In conclusion, the findings confirm that dimensions of impulsivity have discrete neural correlates, and show that relationships between impulsivity and brain structure are expressed differently in adolescents with MDD compared to non-MDD.

Impulsivity modulates performance under response uncertainty in a reaching task.

PubMed

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

2013-03-01

We sought to explore the interaction of the impulsivity trait with response uncertainty. To this end, we used a reaching task (Pellizzer and Hedges 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.

Sex differences in the reduction of impulsive choice (delay discounting) for cocaine in rats with atomoxetine and progesterone

PubMed Central

Smethells, John R.; Swalve, Natashia L.; Eberly, Lynn E.; Carroll, Marilyn E.

2016-01-01

Rationale Impulsive choice, or an inability to delay immediate gratification, has been strongly linked to the development and persistence of drug abuse. Indeed, delaying drug use itself may underlie drug addiction and relapse. Thus, employing treatments that are efficacious in reducing impulsive choice (atomoxetine; ATO) or drug-seeking behavior (progesterone; PRO) may be an effective means of treating drug addiction. Objective The current study assessed sex differences in the effects of PRO, ATO and their combination in a delay discounting paradigm for cocaine and for sucrose pellets. Method Male and female rats chose between a small-immediate or a large-delayed (0, 7.5, 15, 30, 60 sec) outcome in an impulsive choice procedure for sucrose pellets (1 vs 3 pellets) or for iv cocaine infusions (0.3 vs 0.9 mg/kg). Following baseline assessment of impulsive choice, rats received daily treatment of vehicle (VEH), PRO (0.5 mg/kg), ATO (1.5 mg/kg) or a combination (PRO + ATO) until a second assessment of impulsive choice was determined. Results Compared to the VEH group, females were less impulsive for cocaine following PRO or the PRO + ATO combined treatment, whereas males were less impulsive for cocaine following ATO. No treatment effects were observed on impulsive choice for sucrose pellets. Conclusions The present results indicate that impulsive choice for cocaine is reduced by PRO in females and by ATO in males. These findings suggest both treatments may be an effective intervention in treating cocaine abuse, but that their effectiveness differs by sex. PMID:27325394

Role of depression severity and impulsivity in the relationship between hopelessness and suicidal ideation in patients with major depressive disorder.

PubMed

Wang, Yan-yu; Jiang, Neng-zhi; Cheung, Eric F C; Sun, Hong-wei; Chan, Raymond C K

2015-09-01

Hopelessness, depression and impulsivity all contribute to the development of suicidal ideation in patients with major depressive disorder, but the pathway of these factors to suicidal ideation is not clear. This study examined the meditating effect of depression severity on the relationship between hopelessness and suicidal ideation and explored how this mediating effect was moderated by impulsivity. A total of 162 patients with major depressive disorder (MDD) completed a structured clinical diagnostic interview and a battery of scales assessing depression severity, hopelessness, suicidal ideation, and impulsivity. Regression analyses with bootstrapping methods were used to examine the mediating and moderating effects of various risk factors. Mediation analysis revealed a significant indirect effect of hopelessness on suicidal ideation, and the effect was fully mediated through depression severity. On moderation analysis, the moderating effects of the relationship between depression severity and suicidal ideation were significant in both the medium and high impulsivity groups. The present study was limited by the assessment of trait impulsivity and observer-rated depression severity, which might not fully reflect momentary impulsivity and feeling of depression when suicidal ideation occurs. Depression severity plays a mediator role in the relationship between hopelessness and suicidal ideation and this mechanism is contingent on the levels of impulsivity. MDD patients with higher impulsivity appear to be more likely to have suicidal ideations even when they are less depressed. These findings highlight the importance of impulsivity assessment and alleviation of depressive symptoms to prevent suicidality in patients with MDD. Copyright © 2015 Elsevier B.V. All rights reserved.

Differential contributions of cortical thickness and surface area to trait impulsivity in healthy young adults.

PubMed

Kubera, Katharina M; Schmitgen, Mike M; Maier-Hein, Klaus H; Thomann, Philipp A; Hirjak, Dusan; Wolf, Robert C

2018-05-08

Impulsivity is an essential human personality trait and highly relevant for the development of several mental disorders. There is evidence that impulsivity is heritable, yet little is known about neural correlates reflecting early brain development. Here, we address the question whether motor, attentional and non-planning components, as reflected by the Barratt Impulsiveness Scale (BIS-11), are distinctly associated with cortical thickness and surface area variations in young healthy individuals. We investigated cortical thickness and surface area in 54 healthy volunteers (m/f = 30%/70%; age mean/SD = 24.9/4.02) using structural magnetic resonance imaging at 3 T together with surface-based analysis techniques. Impulsivity was examined on the Barratt impulsiveness scale (BIS-11) and related to the two distinct cortical measurements. Higher BIS-11 total scores were negatively associated with cortical thickness variations in the left lingual gyrus, left superior temporal gyrus, right cuneus, and right superior parietal gyrus (p<0.05 cluster-wise probability [CWP] corrected). Higher BIS-11 nonplanning scores were negatively associated with cortical thickness variations in bilateral pericalcarine gyrus (p<0.05 CWP corr.). In the orbitofrontal cortex motor impulsivity associated cortical thickness differs significantly between male and female. These data suggest distinct neurodevelopmental trajectories underlying impulsivity in healthy subjects. Impulsivity total scores appear to be specifically related to cortical thickness variations, in contrast to variations of cortical surface area. Furthermore, our findings underscores the importance of better characterizing gender-specific structural correlates of impulsivity. Copyright © 2018. Published by Elsevier B.V.

Delay discounting and impulsivity traits in young and older gambling disorder patients.

PubMed

Steward, Trevor; Mestre-Bach, Gemma; Fernández-Aranda, Fernando; Granero, Roser; Perales, José C; Navas, Juan Francisco; Soriano-Mas, Carles; Baño, Marta; Fernández-Formoso, Jose A; Martín-Romera, Virginia; Menchón, José M; Jiménez-Murcia, Susana

2017-08-01

Impulsivity is understood to be a multidimensional construct involving aspects such as impulsive choice and impulsive traits. Delay discounting, the tendency to place greater value in immediate rewards over larger, long-term rewards, has been associated with maladaptive choices in gambling disorder (GD). Delay discounting is known to evolve with age; though no study to date has evaluated the interactions between impulsivity, GD severity and age in treatment-seeking patients. We aimed to examine whether associations between delay discounting and impulsivity traits differed between younger and older-aged GD patients. Secondly, we sought to untangle the mediating role of impulsivity in determining gambling behavior in these two age groups. GD patients (N=335) were evaluated using the UPPS-P Impulsive Behavior Scale and a delay discounting task. Structural Equation Modeling (SEM) was used to explore associations between impulsivity measures and gambling severity in young (18-30years) and old (31-70) GD patients. No differences in delay discounting were found between young and old GD patients. Significant correlations between delay discounting and urgency levels (the tendency to act rashly under emotional states) were identified only in the young GD group. Path analyses also revealed both positive and negative urgency to be a mediator of GD severity levels in young GD patients. Significant associations between impulsive choice and positive urgency are only present in young gamblers, suggesting that positive urgency influence choice behavior to a greater degree at younger ages. Implications for targeted interventions are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Intrinsic Network Connectivity Patterns Underlying Specific Dimensions of Impulsiveness in Healthy Young Adults.

PubMed

Kubera, Katharina M; Hirjak, Dusan; Wolf, Nadine D; Sambataro, Fabio; Thomann, Philipp A; Wolf, R Christian

2018-05-01

Impulsiveness is a central human personality trait and of high relevance for the development of several mental disorders. Impulsiveness is a multidimensional construct, yet little is known about dimension-specific neural correlates. Here, we address the question whether motor, attentional and non-planning components, as measured by the Barratt Impulsiveness Scale (BIS-11), are associated with distinct or overlapping neural network activity. In this study, we investigated brain activity at rest and its relationship to distinct dimensions of impulsiveness in 30 healthy young adults (m/f = 13/17; age mean/SD = 26.4/2.6 years) using resting-state functional magnetic resonance imaging at 3T. A spatial independent component analysis and a multivariate model selection strategy were used to identify systems loading on distinct impulsivity domains. We first identified eight networks for which we had a-priori hypotheses. These networks included basal ganglia, cortical motor, cingulate and lateral prefrontal systems. From the eight networks, three were associated with impulsiveness measures (p < 0.05, FDR corrected). There were significant relationships between right frontoparietal network function and all three BIS domains. Striatal and midcingulate network activity was associated with motor impulsiveness only. Within the networks regionally confined effects of age and gender were found. These data suggest distinct and overlapping patterns of neural activity underlying specific dimensions of impulsiveness. Motor impulsiveness appears to be specifically related to striatal and midcingulate network activity, in contrast to a domain-unspecific right frontoparietal system. Effects of age and gender have to be considered in young healthy samples.

Reward Sensitivity and Waiting Impulsivity: Shift towards Reward Valuation away from Action Control

PubMed Central

Mechelmans, Daisy J; Strelchuk, Daniela; Doñamayor, Nuria; Banca, Paula; Robbins, Trevor W; Baek, Kwangyeol

2017-01-01

Abstract Background Impulsivity and reward expectancy are commonly interrelated. Waiting impulsivity, measured using the rodent 5-Choice Serial Reaction Time task, predicts compulsive cocaine seeking and sign (or cue) tracking. Here, we assess human waiting impulsivity using a novel translational task, the 4-Choice Serial Reaction Time task, and the relationship with reward cues. Methods Healthy volunteers (n=29) performed the monetary incentive delay task as a functional MRI study where subjects observe a cue predicting reward (cue) and wait to respond for high (£5), low (£1), or no reward. Waiting impulsivity was tested with the 4-Choice Serial Reaction Time task. Results For high reward prospects (£5, no reward), greater waiting impulsivity on the 4-CSRT correlated with greater medial orbitofrontal cortex and lower supplementary motor area activity to cues. In response to high reward cues, greater waiting impulsivity was associated with greater subthalamic nucleus connectivity with orbitofrontal cortex and greater subgenual cingulate connectivity with anterior insula, but decreased connectivity with regions implicated in action selection and preparation. Conclusion These findings highlight a shift towards regions implicated in reward valuation and a shift towards compulsivity away from higher level motor preparation and action selection and response. We highlight the role of reward sensitivity and impulsivity, mechanisms potentially linking human waiting impulsivity with incentive approach and compulsivity, theories highly relevant to disorders of addiction. PMID:29020291

Living in the Here and Now: Interrelationships between Impulsivity, Mindfulness, and Alcohol Misuse

PubMed Central

Murphy, Cara; MacKillop, James

2013-01-01

Rationale Impulsivity and mindfulness both emphasize orientation to the present, and both have been linked to alcohol misuse, but the relationship between the two is not clearly understood. Objectives To examine the relationships between elements of impulsivity and mindfulness, and to examine both variables in relation to alcohol misuse. Method Young adults (N = 116) were assessed for alcohol use, mindfulness, and impulsivity using psychometrically validated measures. Results Numerous significant associations were present among the facets of impulsivity and mindfulness. The variable most substantially associated with alcohol misuse was Negative Urgency (NU; i.e., proneness to act out under conditions of negative affect). After controlling for other variables, Negative Urgency (NU), Positive Urgency (PU), and delay discounting (DD) were significantly related to alcohol consumption. When examining drinking related consequences, only Lack of Premeditation (LoP) and Negative Urgency (NU) were significant associated. Conclusions There was considerable overlap between some elements of impulsivity and mindfulness while the overlap was negligible for other facets. The associations between mindfulness and alcohol misuse were entirely a function of impulsivity. In particular, acting on impulses while experiencing negative affect was significantly associated with level of alcohol consumption and level of alcohol-related risk. Steep discounting of future rewards was associated with alcohol consumption while poor premeditation was associated with adverse drinking consequences. These findings illustrate the importance of jointly studying impulsivity when examining purported effects of mindfulness traits. PMID:22169883

Impulsivity as a moderator of the associations between child maltreatment types and body mass index.

PubMed

Brown, Shaquanna; Mitchell, Tarrah B; Fite, Paula J; Bortolato, Marco

2017-05-01

Child maltreatment has emerged as an important risk factor for adult obesity (Danese & Tan, 2014; Hemmingsson et al., 2014). However, there is a need for research delineating the factors that play a role in this association. Impulsivity has been shown to be associated with both child maltreatment (Brodsky et al., 2001) and body mass index (BMI; Cortese et al., 2008; Thamotharan et al., 2013). Further, given previous research showing that adverse events interact with impulsivity to predict hazardous drinking behaviors (Fox et al., 2010), there is reason to hypothesize that child maltreatment might interact with impulsivity to predict other adverse health outcomes, such as elevated BMI. Accordingly, the current study examined whether impulsivity moderated the association between child maltreatment types (i.e., physical abuse, physical neglect, sexual abuse, emotional abuse, and emotional neglect) and BMI. The sample was comprised of 500 undergraduate students (49.6% male) between the ages of 18 and 25 years. Regression analyses suggested that maltreatment types and impulsivity were not uniquely associated with BMI. However, impulsivity moderated the association between childhood sexual abuse and adult BMI, such that BMI was highest at high levels of both sexual abuse and impulsivity. Impulsivity did not moderate the associations between the other child maltreatment types and BMI. Limitations, future directions, and clinical implications of this research are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Impulsivity as a moderator of the associations between child maltreatment types and body mass index

PubMed Central

Brown, Shaquanna; Mitchell, Tarrah B.; Fite, Paula J.; Bortolato, Marco

2017-01-01

Child maltreatment has emerged as an important risk factor for adult obesity (Danese & Tan, 2014; Hemmingsson, Johannsson, & Reynisdottir, 2014). However, there is a need for research delineating the factors that play a role in this association. Impulsivity has been shown to be associated with both child maltreatment (Ouyang, Fang, Mercy, Perou, & Grosse, 2008) and body mass index (BMI; Cortese et al., 2008; Thamotharan, Lange, Zale, Huffhines, & Fields, 2013). Further, given previous research showing that adverse events interact with impulsivity to predict hazardous drinking behaviors (Fox, Bergquist, Gu, & Sinha, 2010), there is reason to hypothesize that child maltreatment might interact with impulsivity to predict other adverse health outcomes, such as elevated BMI. Accordingly, the current study examined whether impulsivity moderated the association between child maltreatment types (i.e., physical abuse, physical neglect, sexual abuse, emotional abuse, and emotional neglect) and BMI. The sample was comprised of 500 undergraduate students (49.6% male) between the ages of 18 and 25 years. Regression analyses suggested that maltreatment types and impulsivity were not uniquely associated with BMI. However, impulsivity moderated the association between childhood sexual abuse and adult BMI, such that BMI was highest at high levels of both sexual abuse and impulsivity. Impulsivity did not moderate the associations between the other child maltreatment types and BMI. Limitations, future directions, and clinical implications of this research are discussed. PMID:28262605

Adolescent impulsivity and soft drink consumption: The role of parental regulation.

PubMed

Melbye, Elisabeth L; Bergh, Ingunn H; Hausken, Solveig E S; Sleddens, Ester F C; Glavin, Kari; Lien, Nanna; Bjelland, Mona

2016-01-01

The present study aimed to explore the process in which impulsivity might influence soft drink consumption in adolescents, addressing potential mediating effects of perceived parental regulation regarding unhealthy eating. A cross-sectional survey was performed among 440 13-15-year-olds in Eastern Norway. The survey questionnaire included measures of impulsivity, six types of maternal and paternal regulation (as perceived by the adolescents), and consumption of sugar-sweetened beverages (SSB). Parallel multiple-mediator analyses were performed to reveal potential mediating effects of perceived parental regulatory behaviors on the association between adolescent impulsivity and SSB consumption. Separate models were run for maternal and paternal regulation. Results from our model analyses (both maternal and paternal models) indicated that all the six measured parental regulatory behaviors jointly acted as mediators on the association between adolescent impulsivity and SSB consumption. However, only perceived maternal and paternal legitimacy of regulation showed a unique contribution to the mediated effect. This finding suggests that adolescents' perception of parental legitimate authority is of particular importance in explaining the relationship between impulsivity and unhealthy eating behaviors in adolescents. Future nutrition interventions targeting adolescents and their parents should take personal factors such as adolescents' level of impulsivity into account. Ultimately; what may be an appropriate approach to impulsive individuals and their parents may diverge from what may be an appropriate approach to less impulsive individuals and their parents. Copyright © 2015 Elsevier Ltd. All rights reserved.

Treatment, alcoholics anonymous, and 16-year changes in impulsivity and legal problems among men and women with alcohol use disorders.

PubMed

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

2009-09-01

The link between impulsive personality traits and alcohol use disorders (AUDs) is well established. No studies, however, have investigated whether receipt of help for AUDs predicts change in impulsivity or whether such change is associated with relevant outcomes such as legal problems. The present study examined predictive associations between the duration of help for AUDs (Alcoholics Anonymous [AA], professional treatment) and impulsivity and legal problems over 16 years in men and women with AUDs. Participants who were initially untreated for their AUDs (n(men) = 332, n(women) = 296) completed follow-up telephone interviews at 1 and 16 years after their baseline assessment. Impulsivity and legal problems declined between baseline and the 1-year and 16-year follow-ups among both women and men. A longer duration of participation in AA predicted a decline in impulsivity at both follow-up assessments, and, in turn, a decline in impulsivity predicted a decline in legal problems at Years 1 and 16. In addition, a longer duration of participation in AA predicted fewer legal problems at Year 1, and this association was moderated by gender (significant in men) and impulsivity (significant for individuals with higher baseline scores). The results highlight the potential for AA and professional treatment to reduce the expression of impulsivity and related disinhibitory traits and legal problems in individuals with AUDs.

Modification of impulse generation during piqué turns with increased rotational demands.

PubMed

Zaferiou, Antonia M; Wilcox, Rand R; McNitt-Gray, Jill L

2016-06-01

During initiation of a piqué turn, a dancer generates impulse to achieve the desired lateral translation and whole-body rotation. The goal of this study was to determine how individuals regulate impulse generation when initiating piqué turns with increased rotational demands. Skilled dancers (n=10) performed single (∼360°) and double (∼720°) piqué turns from a stationary position. Linear and angular impulse generated by the push and turn legs were quantified using ground reaction forces and compared across turn conditions as a group and within a dancer using probability-based statistical methods. The results indicate that as the rotation demands of the piqué turn increased, the net angular impulse generated increased whereas net lateral impulse decreased. Early during turn initiation, the free moment contributed to angular impulse generation. Later during turn initiation, horizontal reaction forces were controlled to generate angular impulse. As rotational demands increased, the moment applied increased primarily from redirection of the horizontal reaction force (RFh) at the push leg and a combination of RFh magnitude and moment arm increases at the turn leg. RFh at each leg were coordinated to limit unwanted net linear impulse. Knowledge of observed subject-specific mechanisms is important to inform the design of turning performance training tools. Copyright © 2016 Elsevier B.V. All rights reserved.

Differential effects of co-administration of oxotremorine with SCH 23390 on impulsive choice in high-impulsive rats and low-impulsive rats.

PubMed

Tian, Lin; Qin, Xingna; Sun, Jinling; Li, Xinwang; Wei, Li

2016-03-01

The effect of acetylcholine on impulsive choice is thought to be due to interactions between cholinergic and dopaminergic systems, but this hypothesis has not been proven. This study investigated whether D1-like receptors were involved in the effects of the muscarinic cholinergic agonist oxotremorine on impulsive choice in high-impulsive rats (HI rats, n=8) and low-impulsive rats (LI rats, n=8) characterized by basal levels of impulsive choice in a delay-discounting task. The results revealed that oxotremorine (0.05mg/kg) significantly increased the choice of the large reinforcer in HI rats, whereas decreased the choice of the large reinforcer in LI rats. The D1-like antagonist SCH 23390 produced significant reductions in the large-reinforcer choice in HI rats (0.01mg/kg) and LI rats (0.005, 0.0075, and 0.01mg/kg). SCH 23390 significantly inhibited the increase in the choice of the large reinforcer induced by oxotremorine (0.05mg/kg) in HI rats at doses of 0.005 and 0.0075mg/kg, but enhanced the effect of oxotremorine in LI rats only at the dose of 0.0075mg/kg. These findings suggested that D1-like receptors might be involved in the differential effects of oxotremorine on impulsive choice between HI rats and LI rats. Copyright © 2016 Elsevier Inc. All rights reserved.

Minnesota Impulse Disorders Interview (MIDI): Validation of a structured diagnostic clinical interview for impulse control disorders in an enriched community sample.

PubMed

Chamberlain, Samuel R; Grant, Jon E

2018-07-01

Disorders of impulsivity are common, functionally impairing, and highly relevant across different clinical and research settings. Few structured clinical interviews for the identification and diagnosis of impulse control disorders exist, and none have been validated in a community sample in terms of psychometric properties. The Minnesota Impulse control disorders Interview (MIDI v2.0) was administered to an enriched sample of 293 non-treatment seeking adults aged 18-35 years, recruited using media advertisements in two large US cities. In addition to the MIDI, participants undertook extended clinical interview for other mental disorders, the Barratt impulsiveness questionnaire, and the Padua obsessive-compulsive inventory. The psychometric properties of the MIDI were characterized. In logistic regression, the MIDI showed good concurrent validity against the reference measures (versus gambling disorder interview, p < 0.001; Barratt impulsiveness attentional and non-planning scores p < 0.05), and good discriminant validity versus primarily non-impulsive symptoms, including against anxiety, depression, and obsessive-compulsive symptoms (all p > 0.05). Test re-test reliability was excellent (0.95). The MIDI has good psychometric properties and thus may be a valuable interview tool for clinical and research studies involving impulse control disorders. Further research is needed to better understanding the optimal diagnostic classification and neurobiology of these neglected disorders. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

Instantaneous Impulses.

ERIC Educational Resources Information Center

Erlichson, Herman

2000-01-01

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

A Triadic Reflective-Impulsive-Interoceptive Awareness Model of General and Impulsive Information System Use: Behavioral Tests of Neuro-Cognitive Theory

PubMed Central

Turel, Ofir; Bechara, Antoine

2016-01-01

This study examines a behavioral tripartite model developed in the field of addiction, and applies it here to understanding general and impulsive information technology use. It suggests that technology use is driven by two information-processing brain systems: reflective and impulsive, and that their effects on use are modulated by interoceptive awareness processes. The resultant reflective-impulsive-interoceptive awareness model is tested in two behavioral studies. Both studies employ SEM techniques to time-lagged self-report data from n1 = 300 and n2 = 369 social networking site users. Study 1 demonstrated that temptations augment the effect of habit on technology use, and reduce the effect of satisfaction on use. Study 2 showed that temptations strengthen the effect of habit on impulsive technology use, and weaken the effect of behavioral expectations on impulsive technology use. Hence, the results consistently support the notion that information technology users' behaviors are influenced by reflective and impulsive information processing systems; and that the equilibrium of these systems is determined, at least in part, by one's temptations. These results can serve as a basis for understanding the etiology of modern day addictions. PMID:27199834

Lithium, but not Valproate, Reduces Impulsive Choice in the Delay-Discounting Task in Mice

PubMed Central

Halcomb, Meredith E; Gould, Todd D; Grahame, Nicholas J

2013-01-01

Both lithium and valproate are well-established treatments for bipolar disorder. Studies have also found that lithium is effective at reducing suicidal behaviors in patients with mood disorders. Impulsivity is a validated endophenotype of both bipolar disorder and suicidal behavior. We assessed effects of treatment with lithium or valproate on cognitive impulsivity in selectively bred mice previously shown to manifest relatively high levels of cognitive impulsivity. Mice were trained in the delay-discounting paradigm, a measure of cognitive impulsivity reflecting a behavioral bias towards immediacy, and then treated with lithium, valproate, or control chow. After 3 weeks of drug treatment, mice were tested at various delays to a large, delayed reward. Drug treatment continued during this time. Lithium reduced impulsivity, whereas valproate had no effect on choice behavior. Both drugs increased the number of choice trials and reinforcer intake, but effects on choice behavior did not depend on these motivational changes. To our knowledge, this is the first study demonstrating lithium's effects to reduce cognitive impulsivity. Future studies may focus on the ability of putative pharmacotherapies for patients at risk for bipolar disorder or suicide to modify the impulsive choice dimension of this diseases. PMID:23584261

A Triadic Reflective-Impulsive-Interoceptive Awareness Model of General and Impulsive Information System Use: Behavioral Tests of Neuro-Cognitive Theory.

PubMed

Turel, Ofir; Bechara, Antoine

2016-01-01

This study examines a behavioral tripartite model developed in the field of addiction, and applies it here to understanding general and impulsive information technology use. It suggests that technology use is driven by two information-processing brain systems: reflective and impulsive, and that their effects on use are modulated by interoceptive awareness processes. The resultant reflective-impulsive-interoceptive awareness model is tested in two behavioral studies. Both studies employ SEM techniques to time-lagged self-report data from n 1 = 300 and n 2 = 369 social networking site users. Study 1 demonstrated that temptations augment the effect of habit on technology use, and reduce the effect of satisfaction on use. Study 2 showed that temptations strengthen the effect of habit on impulsive technology use, and weaken the effect of behavioral expectations on impulsive technology use. Hence, the results consistently support the notion that information technology users' behaviors are influenced by reflective and impulsive information processing systems; and that the equilibrium of these systems is determined, at least in part, by one's temptations. These results can serve as a basis for understanding the etiology of modern day addictions.

Effects of cumulative stress and impulsivity on smoking status.

PubMed

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

2012-03-01

The stress-vulnerability model of addiction predicts that environmental factors, such as cumulative stress, will result in individual adaptations that decrease self-control, increase impulsivity, and increase risk for addiction. Impulsivity and cumulative stress are risk factors for tobacco smoking that are rarely examined simultaneously in research. We examined the indirect and direct effects of cumulative adversity in a community sample consisting of 291 men and women who participated in an assessment of cumulative stress, self-reported impulsivity, and smoking history. Data were analyzed using bootstrapping techniques to estimate indirect effects of stress on smoking via impulsivity. Cumulative adversity is associated with smoking status via direct effects and indirect effects through impulsivity scores. Additional models examining specific types of stress indicate contributions of traumatic stress and recent life events as well as chronic relationship stressors. Overall, cumulative stress is associated with increased risk of smoking via increased impulsivity and via pathways independent of impulsivity. These findings support the stress-vulnerability model and highlight the utility of mediation models in assessing how, and for whom, cumulative stress increases risk of current cigarette smoking. Increasing self-control is a target for interventions with individuals who have experienced cumulative adversity. Copyright © 2012 John Wiley & Sons, Ltd.

Effects of cumulative stress and impulsivity on smoking status

PubMed Central

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

2013-01-01

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

Transfers between libration-point orbits in the elliptic restricted problem

NASA Astrophysics Data System (ADS)

Hiday-Johnston, L. A.; Howell, K. C.

1994-04-01

A strategy is formulated to design optimal time-fixed impulsive transfers between three-dimensional libration-point orbits in the vicinity of the interior L1 libration point of the Sun-Earth/Moon barycenter system. The adjoint equation in terms of rotating coordinates in the elliptic restricted three-body problem is shown to be of a distinctly different form from that obtained in the analysis of trajectories in the two-body problem. Also, the necessary conditions for a time-fixed two-impulse transfer to be optimal are stated in terms of the primer vector. Primer vector theory is then extended to nonoptimal impulsive trajectories in order to establish a criterion whereby the addition of an interior impulse reduces total fuel expenditure. The necessary conditions for the local optimality of a transfer containing additional impulses are satisfied by requiring continuity of the Hamiltonian and the derivative of the primer vector at all interior impulses. Determination of location, orientation, and magnitude of each additional impulse is accomplished by the unconstrained minimization of the cost function using a multivariable search method. Results indicate that substantial savings in fuel can be achieved by the addition of interior impulsive maneuvers on transfers between libration-point orbits.

Training impulsive choices for healthy and sustainable food.

PubMed

Veling, Harm; Chen, Zhang; Tombrock, Merel C; Verpaalen, Iris A M; Schmitz, Laura I; Dijksterhuis, Ap; Holland, Rob W

2017-06-01

Many people find it hard to change their dietary choices. Food choice often occurs impulsively, without deliberation, and it has been unclear whether impulsive food choice can be experimentally created. Across 3 exploratory and 2 confirmatory preregistered experiments we examined whether impulsive food choice can be trained. Participants were cued to make motor responses upon the presentation of, among others, healthy and sustainable food items. They subsequently selected these food items more often for actual consumption when they needed to make their choices impulsively as a result of time pressure. This effect disappeared when participants were asked to think about their choices, merely received more time to make their choices, or when choosing required attention to alternatives. Participants preferred high to low valued food items under time pressure and without time pressure, suggesting that the impulsive choices reflect valid preferences. These findings demonstrate that it is possible to train impulsive choices for food items while leaving deliberative choices for these items unaffected, and connect research on attention training to dual-process theories of decision making. The present research suggests that attention training may lead to behavioral change only when people behave impulsively. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Impulsive action: emotional impulses and their control

PubMed Central

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

2014-01-01

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

The relationship between impulsivity and suicide among rural youths aged 15-35 years: a case-control psychological autopsy study.

PubMed

Lin, Lin; Zhang, Jie; Zhou, Li; Jiang, Chao

2016-01-01

In China, the gender ratio of suicide rates did not match the Western patterns, which was higher for females than males. However, the rural men were at relatively high risk of suicide in Liaoning province. Impulsivity was an important factor of suicide behaviors, but there was a lack of studies in China. This research aimed to study the relationship between impulsive personality traits and suicidal behavior among Chinese rural youths. Suicides were consecutively sampled from six randomly selected counties in Liaoning Province in China. Between 2005 and 2007, a total of 162 suicide victims were enrolled in the study along with 162 community controls matched for age, gender, and location. The psychological autopsy method was used to collect data from informants knowledgeable about the selected suicide victims and controls. The results showed the suicide victims in the study were more likely to demonstrate dysfunctional impulsivity and less likely to demonstrate functional impulsivity compared with the controls. Mental disorders, acute negative life events, and dysfunctional impulsivity contributed to the risk of suicide; educational and functional impulsivity were protective factors. Suicide prevention efforts in rural China may address impulsivity.

The Relationship between Impulsivity and Suicide Among Rural Youths Aged 15–35 Years: A Case-Control Psychological Autopsy Study1

PubMed Central

Lin, Lin; Zhang, Jie; Zhou, Li; Jiang, Chao

2015-01-01

In China, the gender ratio of suicide rates did not match the Western patterns, which was higher for females than males. However, the rural men were at relatively high risk of suicide in Liaoning province. Impulsivity was an important factor of suicide behaviors, but there was a lack of studies in China. This research aimed to study the relationship between impulsive personality traits and suicidal behavior among Chinese rural youths. Suicides were consecutively sampled from six randomly selected counties in Liaoning Province in China. Between 2005 and 2007, a total of 162 suicide victims were enrolled in the study along with 162 community controls matched for age, gender, and location. The psychological autopsy method was used to collect data from informants knowledgeable about the selected suicide victims and controls. The results showed the suicide victims in the study were more likely to demonstrate dysfunctional impulsivity and less likely to demonstrate functional impulsivity compared with the controls. Mental disorders, acute negative life events and dysfunctional impulsivity contributed to the risk of suicide; educational and functional impulsivity were protective factors. Suicide prevention efforts in rural China may address impulsivity. PMID:26110614

'Speedy action over goal orientation': cognitive impulsivity in male forensic patients with dyslexia.

PubMed

Dåderman, Anna M; Meurling, Ann Wirsén; Levander, Sten

2012-11-01

Previous neuropsychiatric studies suggest a relationship between reading disability and cognitive impulsivity. This relationship is not entirely explained by the high comorbidity between reading disability and attention deficit hyperactivity disorder (ADHD), as children with a co-occurrence of these disorders tend to be more impulsive than those with ADHD only. Other research has demonstrated that poor verbal skill (irrespective of the presence of dyslexia) deficits in executive functions and impulsivity are important risk factors for criminal behaviour. The present study bridges these two research traditions by examining whether patients undergoing forensic psychiatric investigation who also have dyslexia, have a cognitive style characterized by impulsivity. Male forensic patients (mean age 27 years, range 16-35) with (n = 9) and without (n = 13) dyslexia were evaluated on the computerized EuroCog test battery. The findings suggest that patients with dyslexia tend to use a cognitive impulsive style and suggest a more direct link between dyslexia and cognitive impulsivity that is not mediated by the presence of ADHD. In order to identify treatment needs and tailor treatment accordingly, forensic patients should be assessed with respect to poor verbal skill, dyslexia and impulsivity. Copyright © 2012 John Wiley & Sons, Ltd.