Methods and apparatuses for self-generating fault-tolerant keys in spread-spectrum systems

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

Moradi, Hussein; Farhang, Behrouz; Subramanian, Vijayarangam

Self-generating fault-tolerant keys for use in spread-spectrum systems are disclosed. At a communication device, beacon signals are received from another communication device and impulse responses are determined from the beacon signals. The impulse responses are circularly shifted to place a largest sample at a predefined position. The impulse responses are converted to a set of frequency responses in a frequency domain. The frequency responses are shuffled with a predetermined shuffle scheme to develop a set of shuffled frequency responses. A set of phase differences is determined as a difference between an angle of the frequency response and an angle ofmore » the shuffled frequency response at each element of the corresponding sets. Each phase difference is quantized to develop a set of secret-key quantized phases and a set of spreading codes is developed wherein each spreading code includes a corresponding phase of the set of secret-key quantized phases.« less

Spatio-Temporal Dynamics of Impulse Responses to Figure Motion in Optic Flow Neurons

PubMed Central

Lee, Yu-Jen; Jönsson, H. Olof; Nordström, Karin

2015-01-01

White noise techniques have been used widely to investigate sensory systems in both vertebrates and invertebrates. White noise stimuli are powerful in their ability to rapidly generate data that help the experimenter decipher the spatio-temporal dynamics of neural and behavioral responses. One type of white noise stimuli, maximal length shift register sequences (m-sequences), have recently become particularly popular for extracting response kernels in insect motion vision. We here use such m-sequences to extract the impulse responses to figure motion in hoverfly lobula plate tangential cells (LPTCs). Figure motion is behaviorally important and many visually guided animals orient towards salient features in the surround. We show that LPTCs respond robustly to figure motion in the receptive field. The impulse response is scaled down in amplitude when the figure size is reduced, but its time course remains unaltered. However, a low contrast stimulus generates a slower response with a significantly longer time-to-peak and half-width. Impulse responses in females have a slower time-to-peak than males, but are otherwise similar. Finally we show that the shapes of the impulse response to a figure and a widefield stimulus are very similar, suggesting that the figure response could be coded by the same input as the widefield response. PMID:25955416

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.

Associations between regional brain physiology and trait impulsivity, motor inhibition, and impaired control over drinking

PubMed Central

Weafer, Jessica; Dzemidzic, Mario; Eiler, William; Oberlin, Brandon G.; Wang, Yang; Kareken, David A.

2015-01-01

Trait impulsivity and poor inhibitory control are well-established risk factors for alcohol misuse, yet little is known about the associated neurobiological endophenotypes. Here we examined correlations among brain physiology and self-reported trait impulsive behavior, impaired control over drinking, and a behavioral measure of response inhibition. A sample of healthy drinkers (n=117) completed a pulsed arterial spin labeling (PASL) scan to quantify resting regional cerebral blood flow (rCBF), and measures of self-reported impulsivity (Eysenck I7 Impulsivity scale) and impaired control over drinking. A subset of subjects (n=40) performed a stop signal task during blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging to assess brain regions involved in response inhibition. Eysenck I7 scores were inversely related to blood flow in the right precentral gyrus. Significant BOLD activation during response inhibition occurred in an overlapping right frontal motor/premotor region. Moreover, impaired control over drinking was associated with reduced BOLD response in the same region. These findings suggest that impulsive personality and impaired control over drinking are associated with brain physiology in areas implicated in response inhibition. This is consistent with the idea that difficulty controlling behavior is due in part to impairment in motor restraint systems. PMID:26065376

Correlation Filtering of Modal Dynamics using the Laplace Wavelet

NASA Technical Reports Server (NTRS)

Freudinger, Lawrence C.; Lind, Rick; Brenner, Martin J.

1997-01-01

Wavelet analysis allows processing of transient response data commonly encountered in vibration health monitoring tasks such as aircraft flutter testing. The Laplace wavelet is formulated as an impulse response of a single mode system to be similar to data features commonly encountered in these health monitoring tasks. A correlation filtering approach is introduced using the Laplace wavelet to decompose a signal into impulse responses of single mode subsystems. Applications using responses from flutter testing of aeroelastic systems demonstrate modal parameters and stability estimates can be estimated by correlation filtering free decay data with a set of Laplace wavelets.

Identification of Linear and Nonlinear Aerodynamic Impulse Responses Using Digital Filter Techniques

NASA Technical Reports Server (NTRS)

Silva, Walter A.

1997-01-01

This paper discusses the mathematical existence and the numerically-correct identification of linear and nonlinear aerodynamic impulse response functions. Differences between continuous-time and discrete-time system theories, which permit the identification and efficient use of these functions, will be detailed. Important input/output definitions and the concept of linear and nonlinear systems with memory will also be discussed. It will be shown that indicial (step or steady) responses (such as Wagner's function), forced harmonic responses (such as Theodorsen's function or those from doublet lattice theory), and responses to random inputs (such as gusts) can all be obtained from an aerodynamic impulse response function. This paper establishes the aerodynamic impulse response function as the most fundamental, and, therefore, the most computationally efficient, aerodynamic function that can be extracted from any given discrete-time, aerodynamic system. The results presented in this paper help to unify the understanding of classical two-dimensional continuous-time theories with modern three-dimensional, discrete-time theories. First, the method is applied to the nonlinear viscous Burger's equation as an example. Next the method is applied to a three-dimensional aeroelastic model using the CAP-TSD (Computational Aeroelasticity Program - Transonic Small Disturbance) code and then to a two-dimensional model using the CFL3D Navier-Stokes code. Comparisons of accuracy and computational cost savings are presented. Because of its mathematical generality, an important attribute of this methodology is that it is applicable to a wide range of nonlinear, discrete-time problems.

Identification of Linear and Nonlinear Aerodynamic Impulse Responses Using Digital Filter Techniques

NASA Technical Reports Server (NTRS)

Silva, Walter A.

1997-01-01

This paper discusses the mathematical existence and the numerically-correct identification of linear and nonlinear aerodynamic impulse response functions. Differences between continuous-time and discrete-time system theories, which permit the identification and efficient use of these functions, will be detailed. Important input/output definitions and the concept of linear and nonlinear systems with memory will also be discussed. It will be shown that indicial (step or steady) responses (such as Wagner's function), forced harmonic responses (such as Tbeodorsen's function or those from doublet lattice theory), and responses to random inputs (such as gusts) can all be obtained from an aerodynamic impulse response function. This paper establishes the aerodynamic impulse response function as the most fundamental, and, therefore, the most computationally efficient, aerodynamic function that can be extracted from any given discrete-time, aerodynamic system. The results presented in this paper help to unify the understanding of classical two-dimensional continuous-time theories with modem three-dimensional, discrete-time theories. First, the method is applied to the nonlinear viscous Burger's equation as an example. Next the method is applied to a three-dimensional aeroelastic model using the CAP-TSD (Computational Aeroelasticity Program - Transonic Small Disturbance) code and then to a two-dimensional model using the CFL3D Navier-Stokes code. Comparisons of accuracy and computational cost savings are presented. Because of its mathematical generality, an important attribute of this methodology is that it is applicable to a wide range of nonlinear, discrete-time problems.

Channel Modelling and Performance of Non-Line-of-Sight Ultraviolet Scattering Communications

DTIC Science & Technology

2012-01-01

Avalanche photodiode (APD) detectors are also rapidly being developed [6, 7]. These device advances have inspired recent research in LED-based short...response and path loss results for outdoor NLOS UV communication channels in Section 3. The impulse response modelling describes UV pulse broadening via...Both the impulse response and path loss are critical to communication system design and performance assessment. Although pulse broadening creates inter

Multi-channel spatialization systems for audio signals

NASA Technical Reports Server (NTRS)

Begault, Durand R. (Inventor)

1993-01-01

Synthetic head related transfer functions (HRTF's) for imposing reprogrammable spatial cues to a plurality of audio input signals included, for example, in multiple narrow-band audio communications signals received simultaneously are generated and stored in interchangeable programmable read only memories (PROM's) which store both head related transfer function impulse response data and source positional information for a plurality of desired virtual source locations. The analog inputs of the audio signals are filtered and converted to digital signals from which synthetic head related transfer functions are generated in the form of linear phase finite impulse response filters. The outputs of the impulse response filters are subsequently reconverted to analog signals, filtered, mixed, and fed to a pair of headphones.

Multi-channel spatialization system for audio signals

NASA Technical Reports Server (NTRS)

Begault, Durand R. (Inventor)

1995-01-01

Synthetic head related transfer functions (HRTF's) for imposing reprogramable spatial cues to a plurality of audio input signals included, for example, in multiple narrow-band audio communications signals received simultaneously are generated and stored in interchangeable programmable read only memories (PROM's) which store both head related transfer function impulse response data and source positional information for a plurality of desired virtual source locations. The analog inputs of the audio signals are filtered and converted to digital signals from which synthetic head related transfer functions are generated in the form of linear phase finite impulse response filters. The outputs of the impulse response filters are subsequently reconverted to analog signals, filtered, mixed and fed to a pair of headphones.

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.

Optimization and Comparison of Different Digital Mammographic Tomosynthesis Reconstruction Methods

DTIC Science & Technology

2008-04-01

physical measurements of impulse response analysis, modulation transfer function (MTF) and noise power spectrum (NPS). (Months 5- 12). This task has...and 2 impulse -added: projection images with simulated impulse and the I /r2 shading difference. Other system blur and noise issues are not...blur, and suppressed high frequency noise . Point-by-point BP rather than traditional SAA should be considered as the basis of further deblurring

Determination of acoustical transfer functions using an impulse method

NASA Astrophysics Data System (ADS)

MacPherson, J.

1985-02-01

The Transfer Function of a system may be defined as the relationship of the output response to the input of a system. Whilst recent advances in digital processing systems have enabled Impulse Transfer Functions to be determined by computation of the Fast Fourier Transform, there has been little work done in applying these techniques to room acoustics. Acoustical Transfer Functions have been determined for auditoria, using an impulse method. The technique is based on the computation of the Fast Fourier Transform (FFT) of a non-ideal impulsive source, both at the source and at the receiver point. The Impulse Transfer Function (ITF) is obtained by dividing the FFT at the receiver position by the FFT of the source. This quantity is presented both as linear frequency scale plots and also as synthesized one-third octave band data. The technique enables a considerable quantity of data to be obtained from a small number of impulsive signals recorded in the field, thereby minimizing the time and effort required on site. As the characteristics of the source are taken into account in the calculation, the choice of impulsive source is non-critical. The digital analysis equipment required for the analysis is readily available commercially.

Arbitrary magnetic field gradient waveform correction using an impulse response based pre-equalization technique.

PubMed

Goora, Frédéric G; Colpitts, Bruce G; Balcom, Bruce J

2014-01-01

The time-varying magnetic fields used in magnetic resonance applications result in the induction of eddy currents on conductive structures in the vicinity of both the sample under investigation and the gradient coils. These eddy currents typically result in undesired degradations of image quality for MRI applications. Their ubiquitous nature has resulted in the development of various approaches to characterize and minimize their impact on image quality. This paper outlines a method that utilizes the magnetic field gradient waveform monitor method to directly measure the temporal evolution of the magnetic field gradient from a step-like input function and extracts the system impulse response. With the basic assumption that the gradient system is sufficiently linear and time invariant to permit system theory analysis, the impulse response is used to determine a pre-equalized (optimized) input waveform that provides a desired gradient response at the output of the system. An algorithm has been developed that calculates a pre-equalized waveform that may be accurately reproduced by the amplifier (is physically realizable) and accounts for system limitations including system bandwidth, amplifier slew rate capabilities, and noise inherent in the initial measurement. Significant improvements in magnetic field gradient waveform fidelity after pre-equalization have been realized and are summarized. Copyright © 2013 Elsevier Inc. All rights reserved.

An improved algorithm for balanced POD through an analytic treatment of impulse response tails

NASA Astrophysics Data System (ADS)

Tu, Jonathan H.; Rowley, Clarence W.

2012-06-01

We present a modification of the balanced proper orthogonal decomposition (balanced POD) algorithm for systems with simple impulse response tails. In this new method, we use dynamic mode decomposition (DMD) to estimate the slowly decaying eigenvectors that dominate the long-time behavior of the direct and adjoint impulse responses. This is done using a new, low-memory variant of the DMD algorithm, appropriate for large datasets. We then formulate analytic expressions for the contribution of these eigenvectors to the controllability and observability Gramians. These contributions can be accounted for in the balanced POD algorithm by simply appending the impulse response snapshot matrices (direct and adjoint, respectively) with particular linear combinations of the slow eigenvectors. Aside from these additions to the snapshot matrices, the algorithm remains unchanged. By treating the tails analytically, we eliminate the need to run long impulse response simulations, lowering storage requirements and speeding up ensuing computations. To demonstrate its effectiveness, we apply this method to two examples: the linearized, complex Ginzburg-Landau equation, and the two-dimensional fluid flow past a cylinder. As expected, reduced-order models computed using an analytic tail match or exceed the accuracy of those computed using the standard balanced POD procedure, at a fraction of the cost.

THz impulse radar for biomedical sensing: nonlinear system behavior

NASA Astrophysics Data System (ADS)

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

2014-03-01

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

Impulsive-choice patterns for food in genetically lean and obese Zucker rats

PubMed Central

Boomhower, Steven R.; Rasmussen, Erin B.; Doherty, Tiffany S.

2012-01-01

Behavioral-economic studies have shown that differences between lean and obese Zuckers in food consumption depend on the response requirement for food. Since a response requirement inherently increases the delay to reinforcement, differences in sensitivity to delay may also be a relevant mechanism of food consumption in the obese Zucker rat. Furthermore, the endocannabinoid neurotransmitter system has been implicated in impulsivity, but studies that attempt to characterize the effects of cannabinoid drugs (e.g., rimonabant) on impulsive choice may be limited by floor effects. The present study aimed to characterize impulsive-choice patterns for sucrose using an adjusting-delay procedure in genetically lean and obese Zuckers. Ten lean and ten obese Zucker rats chose between one lever that resulted in one pellet after a standard delay (either 1 s or 5 s) and a second lever that resulted in two or three pellets after an adjusting delay. After behavior stabilized under baseline, rimonabant (0–10 mg/kg) was administered prior to some choice sessions in the two-pellet condition. Under baseline, obese Zuckers made more impulsive choices than leans in three of the four standard-delay/pellet conditions. Additionally, in the 2-pellet condition, rimonabant increased impulsive choice in lean rats in the 1-s standard-delay condition; however, rimonabant decreased impulsive choice in obese rats in the 1-s and 5-s standard-delay conditions. These data suggest that genetic factors that influence impulsive choice are stronger in some choice conditions than others, and that the endocannabinoid system may be a relevant neuromechanism. PMID:23261877

Impulsive-choice patterns for food in genetically lean and obese Zucker rats.

PubMed

Boomhower, Steven R; Rasmussen, Erin B; Doherty, Tiffany S

2013-03-15

Behavioral-economic studies have shown that differences between lean and obese Zuckers in food consumption depend on the response requirement for food. Since a response requirement inherently increases the delay to reinforcement, differences in sensitivity to delay may also be a relevant mechanism of food consumption in the obese Zucker rat. Furthermore, the endocannabinoid neurotransmitter system has been implicated in impulsivity, but studies that attempt to characterize the effects of cannabinoid drugs (e.g., rimonabant) on impulsive choice may be limited by floor effects. The present study aimed to characterize impulsive-choice patterns for sucrose using an adjusting-delay procedure in genetically lean and obese Zuckers. Ten lean and ten obese Zucker rats chose between one lever that resulted in one pellet after a standard delay (either 1 s or 5 s) and a second lever that resulted in two or three pellets after an adjusting delay. After behavior stabilized under baseline, rimonabant (0-10 mg/kg) was administered prior to some choice sessions in the two-pellet condition. Under baseline, obese Zuckers made more impulsive choices than leans in three of the four standard-delay/pellet conditions. Additionally, in the 2-pellet condition, rimonabant increased impulsive choice in lean rats in the 1-s standard-delay condition; however, rimonabant decreased impulsive choice in obese rats in the 1-s and 5-s standard-delay conditions. These data suggest that genetic factors that influence impulsive choice are stronger in some choice conditions than others, and that the endocannabinoid system may be a relevant neuromechanism. Copyright © 2012 Elsevier B.V. All rights reserved.

Three-dimensional FLASH Laser Radar Range Estimation via Blind Deconvolution

DTIC Science & Technology

2009-10-01

scene can result in errors due to several factors including the optical spatial impulse response, detector blurring, photon noise , timing jitter, and...estimation error include spatial blur, detector blurring, noise , timing jitter, and inter-sample targets. Unlike previous research, this paper ac- counts...for pixel coupling by defining the range image mathematical model as a 2D convolution between the system spatial impulse response and the object (target

Imaging through Scattering Media with Grating-Based Interferometers.

DTIC Science & Technology

1980-12-01

Theoretically, if the instantaneous impulse response nf the scat- tering medium can be measured and an inverse filter [7, 8] can be created in real time, it... impulse response of a time- varying volume scattering medium. Moreover, no modulator appears to possess the required temporal and spatial bandwidth for...or optical deblurring techniques. Thirdly, since the achromatic grating interferometric system discriminates by the directions of propa- gation, the

Kinetics of cycle length dependence of ventricular repolarization: effect of autonomic blockade

NASA Technical Reports Server (NTRS)

Raeder, E. A.; Albrecht, P.; Perrott, M.; Cohen, R. J.

1995-01-01

INTRODUCTION: Beat-to-beat adaptation of ventricular repolarization duration to cardiac cycle length and autonomic activity has not been previously characterized in the spontaneously beating human heart. METHODS AND RESULTS: The ECG of 14 healthy subjects was recorded from the supine and upright positions. Autonomic blockade was accomplished by atropine and propranolol. RR and RT intervals were measured by a computer algorithm, and the impulse response (h) from RR to RT computed. In the supine position the maximal adjustment of the RT interval occurred in the first beat following a change in cycle length (hpeak = 17.8 +/- 1.6 msec/sec), but continued to be detectable for 3.8 seconds (2.9-4.7 sec). Propranolol attenuated the peak impulse response to 15.8 +/- 4.0 msec/sec (P = NS). In the standing position the peak impulse response was increased to 25.2 +/- 5.0 msec/sec (P = 0.004 vs supine), and the impulse response duration (hdur) shortened to 1.4 seconds (1.3-1.6). This was reversed by beta blockade (hpeak = 10.7 +/- 3.6 [P = 0.005 vs standing]; hdur = 5.5 sec [4.8-6.1]). Parasympathetic and combined autonomic blockade resulted in too little residual heart rate variability to estimate the impulse response accurately. The slope of the regression of delta RT and delta RR in the supine position was 0.0177 +/- 0.0016, which was closely correlated with the peak impulse response (r = 0.91). CONCLUSIONS: System identification techniques can assist in characterizing the cycle dependence of ventricular repolarization and may provide new insights into conditions associated with abnormal repolarization.

Development and automation of a test of impulse control in zebrafish

PubMed Central

Parker, Matthew O.; Ife, Dennis; Ma, Jun; Pancholi, Mahesh; Smeraldi, Fabrizio; Straw, Chris; Brennan, Caroline H.

2013-01-01

Deficits in impulse control (difficulties in inhibition of a pre-potent response) are fundamental to a number of psychiatric disorders, but the molecular and cellular basis is poorly understood. Zebrafish offer a very useful model for exploring these mechanisms, but there is currently a lack of validated procedures for measuring impulsivity in fish. In mammals, impulsivity can be measured by examining rates of anticipatory responding in the 5-choice serial reaction time task (5-CSRTT), a continuous performance task where the subject is reinforced upon accurate detection of a briefly presented light in one of five distinct spatial locations. This paper describes the development of a fully-integrated automated system for testing impulsivity in adult zebrafish. We outline the development of our image analysis software and its integration with National Instruments drivers and actuators to produce the system. We also describe an initial validation of the system through a one-generation screen of chemically mutagenized zebrafish, where the testing parameters were optimized. PMID:24133417

Is impulsivity a link between childhood abuse and suicide?

PubMed

Braquehais, M Dolores; Oquendo, Maria A; Baca-García, Enrique; Sher, Leo

2010-01-01

Childhood abuse and neglect are known to affect psychological states through behavioral, emotional, and cognitive pathways. They increase the risk of having psychiatric diseases in adulthood and have been considered risk factors for suicidal behavior in all diagnostic categories. Early, prolonged, and severe trauma is also known to increase impulsivity, diminishing the capacity of the brain to inhibit negative actions and to control and modulate emotions. Many neurobiological studies hold that childhood maltreatment may lead to a persistent failure of the inhibitory processes ruled mainly by the frontal cortex over a fear-motivated hyperresponsive limbic system. Multiple neurotransmitters and hormones are involved in the stress response, but, to our knowledge, the two major biological consequences of the chronic exposure to trauma are the hypofunction of the serotonergic system and changes in the hypothalamic-pituitary-adrenal axis function. Some of these findings overlap with the neurobiological features of impulsivity and of suicidal behavior. Impulsivity has also been said to be both a consequence of trauma and a risk factor for the development of a pathological response to trauma. Thus, we suggest that impulsivity could be one of the links between childhood trauma and suicidal behavior. Prevention of childhood abuse could significantly reduce suicidal behavior in adolescents and adults, in part, through a decrease in the frequency of impulsive behaviors in the future. Copyright 2010 Elsevier Inc. All rights reserved.

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

Periodic components of hand acceleration/deceleration impulses during telemanipulation

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

Draper, J.V.; Handel, S.

1994-01-01

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

Impulsive response of an automatic transmission system with multiple clearances: Formulation, simulation and experiment

NASA Astrophysics Data System (ADS)

Crowther, Ashley R.; Singh, Rajendra; Zhang, Nong; Chapman, Chris

2007-10-01

Impulsive responses in geared systems with multiple clearances are studied when the mean torque excitation and system load change abruptly, with application to a vehicle driveline with an automatic transmission. First, torsional lumped-mass models of the planetary and differential gear sets are formulated using matrix elements. The model is then reduced to address tractable nonlinear problems while successfully retaining the main modes of interest. Second, numerical simulations for the nonlinear model are performed for transient conditions and a typical driving situation that induces an impulsive behaviour simulated. However, initial conditions and excitation and load profiles have to be carefully defined before the model can be numerically solved. It is shown that the impacts within the planetary or differential gears may occur under combinations of engine, braking and vehicle load transients. Our analysis shows that the shaping of the engine transient by the torque converter before reaching the clearance locations is more critical. Third, a free vibration experiment is developed for an analogous driveline with multiple clearances and three experiments that excite different response regimes have been carried out. Good correlations validate the proposed methodology.

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.

Impulse control and restrained eating among young women: Evidence for compensatory cortical activation during a chocolate-specific delayed discounting task.

PubMed

Dong, Debo; Wang, Yulin; Jackson, Todd; Chen, Shuaiyu; Wang, Yu; Zhou, Feng; Chen, Hong

2016-10-01

Theory and associated research indicate that people with elevated restrained eating (RE) scores have higher risk for binge eating, future bulimic symptom onset and weight gain. Previous imaging studies have suggested hyper-responsive reward brain area activation in response to food cues contributes to this risk but little is known about associated neural impulse control mechanisms, especially when considering links between depleted cognitive resources related to unsuccessful RE. Towards illuminating this issue, we used a chocolate-specific delayed discounting (DD) task to investigate relations between RE scores, behavior impulsivity, and corresponding neural impulse control correlates in a functional magnetic resonance imaging (fMRI) study of 27 young women. Specifically, participants were required to choose between more immediate, smaller versus delayed, larger hypothetical chocolate rewards following initial consumption of a chocolate. As predicted, RE scores were correlated positively with behavior impulse control levels. More critically, higher RE scores were associated with stronger activation in impulse control region, the dorsal-lateral prefrontal cortex (DLPFC) during the completion of difficult decision trials reflecting higher cognitive demands and resource depletion relative to easy decision trials. Exploratory analyses revealed a positive correlation between RE scores and activity in a reward system hub, the right striatum. Moreover, a positive correlation between left DLPFC and striatum activation was posited to reflect, in part, impulse control region compensation in response to stronger reward signal among women with RE elevations. Findings suggested impulse control lapses may contribute to difficulties in maintaining RE, particularly when cognitive demands are high. Copyright © 2016. Published by Elsevier Ltd.

Hazardous drinking and dimensions of impulsivity, behavioral approach, and inhibition in adult men and women.

PubMed

Hamilton, Kristen R; Sinha, Rajita; Potenza, Marc N

2012-06-01

Hazardous drinking is characterized by decisions to engage in excessive or risky patterns of alcohol consumption. Levels of impulsivity and behavioral approach and inhibition may differ in hazardous drinkers and nonhazardous drinkers. A comparison of the relative levels of dimensions of impulsivity and behavioral inhibition and approach in adult men and women hazardous and nonhazardous drinkers may inform treatment and prevention efforts. In the present research, 466 men and women from a community sample were administered the Alcohol Use Disorders Identification Test (AUDIT), the Behavioral Inhibition System/Behavioral Approach System (BIS/BAS) scale, and the Barratt Impulsiveness Scale, version 11 (BIS-11). Relations among the dimensions of these constructs were examined using multivariate analysis of covariance (MANCOVA), with age and race as covariates. There were main effects of hazardous drinking on all 3 dimensions of impulsivity, the behavioral inhibition system, and the behavioral activation system Reward Responsiveness, and Fun-Seeking components, with hazardous drinkers scoring higher than nonhazardous drinkers. This research provides a better understanding of the manner in which impulsivity and behavioral inhibition and approach tendencies relate to hazardous alcohol use in men and women. The present results have implications for alcohol-related prevention and treatment strategies for adult men and women. Copyright © 2012 by the Research Society on Alcoholism.

Characterization Of Improved Binary Phase-Only Filters In A Real-Time Coherent Optical Correlation System

NASA Astrophysics Data System (ADS)

Flannery, D.; Keller, P.; Cartwright, S.; Loomis, J.

1987-06-01

Attractive correlation system performance potential is possible using magneto-optic spatial light modulators (SLM) to implement binary phase-only reference filters at high rates, provided the correlation performance of such reduced-information-content filters is adequate for the application. In the case studied here, the desired filter impulse response is a rectangular shape, which cannot be achieved with the usual binary phase-only filter formulation. The correlation application problem is described and techniques for synthesizing improved filter impulse response are considered. A compromise solution involves the cascading of a fixed amplitude-only weighting mask with the binary phase-only SLM. Based on simulations presented, this approach provides improved impulse responses and good correlation performance, while retaining the critical feature of real-time variations of the size, shape, and orientation of the rectangle by electronic programming of the phase pattern in the SLM. Simulations indicate that, for at least one very challenging input scene clutter situation, these filters provide higher correlation signal-to-noise than does "ideal" correlation, i.e. using a perfect rectangle filter response.

FIR signature verification system characterizing dynamics of handwriting features

NASA Astrophysics Data System (ADS)

Thumwarin, Pitak; Pernwong, Jitawat; Matsuura, Takenobu

2013-12-01

This paper proposes an online signature verification method based on the finite impulse response (FIR) system characterizing time-frequency characteristics of dynamic handwriting features. First, the barycenter determined from both the center point of signature and two adjacent pen-point positions in the signing process, instead of one pen-point position, is used to reduce the fluctuation of handwriting motion. In this paper, among the available dynamic handwriting features, motion pressure and area pressure are employed to investigate handwriting behavior. Thus, the stable dynamic handwriting features can be described by the relation of the time-frequency characteristics of the dynamic handwriting features. In this study, the aforesaid relation can be represented by the FIR system with the wavelet coefficients of the dynamic handwriting features as both input and output of the system. The impulse response of the FIR system is used as the individual feature for a particular signature. In short, the signature can be verified by evaluating the difference between the impulse responses of the FIR systems for a reference signature and the signature to be verified. The signature verification experiments in this paper were conducted using the SUBCORPUS MCYT-100 signature database consisting of 5,000 signatures from 100 signers. The proposed method yielded equal error rate (EER) of 3.21% on skilled forgeries.

Time Delay Estimation

DTIC Science & Technology

1976-04-09

of the signal and noise remain HH ***^-^*--~ 53 h, to r(Mc) h2(r» r(we) Figure 3-2 Sy&toetric Impulse Response for Two FIR Linear Phase...Inputs x,y and Outputs x.j. , 15 2-2 Linear System with Impulse Response h("r) 23 2-3 Model of Error Resulting from Linearly Filtering x(t) to...Corrupted with Additive Noise 42 2-6 Model of Directional Signal Corrupted with Additive Noise and Processed .... 45 2-7 Source Driving Two

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.

High-frequency vibration energy harvesting from impulsive excitation utilizing intentional dynamic instability caused by strong nonlinearity

NASA Astrophysics Data System (ADS)

Remick, Kevin; Dane Quinn, D.; Michael McFarland, D.; Bergman, Lawrence; Vakakis, Alexander

2016-05-01

The authors investigate a vibration-based energy harvesting system utilizing essential (nonlinearizable) nonlinearities and electromagnetic coupling elements. The system consists of a grounded, weakly damped linear oscillator (primary system) subjected to a single impulsive load. This primary system is coupled to a lightweight, damped oscillating attachment (denoted as nonlinear energy sink, NES) via a neodymium magnet and an inductance coil, and a piano wire, which generates an essential geometric cubic stiffness nonlinearity. Under impulsive input, the transient damped dynamics of this system exhibit transient resonance captures (TRCs) causing intentional large-amplitude and high-frequency instabilities in the response of the NES. These TRCs result in strong energy transfer from the directly excited primary system to the light-weight attachment. The energy is harvested by the electromagnetic elements in the coupling and, in the present case, dissipated in a resistive element in the electrical circuit. The primary goal of this work is to numerically, analytically, and experimentally demonstrate the efficacy of employing this type of intentional high-frequency dynamic instability to achieve enhanced vibration energy harvesting under impulsive excitation.

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.

Impulse Response Shaping for Ultra Wide Band SAR in a Circular Flight Path

NASA Technical Reports Server (NTRS)

Jin, Michael Y.

1996-01-01

An ultra wide band SAR (synthetic aperture radar) has potential applications on imaging underground objects. Flying this SAR in a circular flight path is an efficient way to acquire high resolution images from a localized area. This paper characterizes the impulse response of sucha system. The results indicate that to achieve an image with a more uniformed resolution over the entire imaged area, proper weighting coeficients should be applied to both the principle aperture and the complimentary aperture.

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

Endocannabinoids and striatal function: implications for addiction-related behaviours

PubMed Central

Moreira, Fabricio A.; Jupp, Bianca; Belin, David

2015-01-01

Since the identification and cloning of the major cannabinoid receptor expressed in the brain almost 25 years ago research has highlighted the potential of drugs that target the endocannabinoid system for treating addiction. The endocannabinoids, anandamide and 2-arachidonoyl glycerol, are lipid-derived metabolites found in abundance in the basal ganglia and other brain areas innervated by the mesocorticolimbic dopamine systems. Cannabinoid CB1 receptor antagonists/inverse agonists reduce reinstatement of responding for cocaine, alcohol and opiates in rodents. However, compounds acting on the endocannabinoid system may have broader application in treating drug addiction by ameliorating associated traits and symptoms such as impulsivity and anxiety that perpetuate drug use and interfere with rehabilitation. As a trait, impulsivity is known to predispose to addiction and facilitate the emergence of addiction to stimulant drugs. In contrast, anxiety and elevated stress responses accompany extended drug use and may underlie the persistence of drug intake in dependent individuals. In this article we integrate and discuss recent findings in rodents showing selective pharmacological modulation of impulsivity and anxiety by cannabinoid agents. We highlight the potential of selective inhibitors of endocannabinoid metabolism, directed at fatty acid amide hydrolase and monoacylglycerol lipase, to reduce anxiety and stress responses, and discuss novel mechanisms underlying the modulation of the endocannabinoid system, including the attenuation of impulsivity, anxiety, and drug reward by selective CB2 receptor agonists. PMID:25369747

Acoustic impulse response method as a source of undergraduate research projects and advanced laboratory experiments.

PubMed

Robertson, W M; Parker, J M

2012-03-01

A straightforward and inexpensive implementation of acoustic impulse response measurement is described utilizing the signal processing technique of coherent averaging. The technique is capable of high signal-to-noise measurements with personal computer data acquisition equipment, an amplifier/speaker, and a high quality microphone. When coupled with simple waveguide test systems fabricated from commercial PVC plumbing pipe, impulse response measurement has proven to be ideal for undergraduate research projects-often of publishable quality-or for advanced laboratory experiments. The technique provides important learning objectives for science or engineering students in areas such as interfacing and computer control of experiments; analog-to-digital conversion and sampling; time and frequency analysis using Fourier transforms; signal processing; and insight into a variety of current research areas such as acoustic bandgap materials, acoustic metamaterials, and fast and slow wave manipulation. © 2012 Acoustical Society of America

Optimal spatial filtering and transfer function for SAR ocean wave spectra

NASA Technical Reports Server (NTRS)

Beal, R. C.; Tilley, D. G.

1981-01-01

The impulse response of the SAR system is not a delta function and the spectra represent the product of the underlying image spectrum with the transform of the impulse response which must be removed. A digitally computed spectrum of SEASAT imagery of the Atlantic Ocean east of Cape Hatteras was smoothed with a 5 x 5 convolution filter and the trend was sampled in a direction normal to the predominant wave direction. This yielded a transform of a noise-like process. The smoothed value of this trend is the transform of the impulse response. This trend is fit with either a second- or fourth-order polynomial which is then used to correct the entire spectrum. A 16 x 16 smoothing of the spectrum shows the presence of two distinct swells. Correction of the effects of speckle is effected by the subtraction of a bias from the spectrum.

Metacognitive Control of Categorial Neurobehavioral Decision Systems

PubMed Central

Foxall, Gordon R.

2016-01-01

The competing neuro-behavioral decision systems (CNDS) model proposes that the degree to which an individual discounts the future is a function of the relative hyperactivity of an impulsive system based on the limbic and paralimbic brain regions and the relative hypoactivity of an executive system based in prefrontal cortex (PFC). The model depicts the relationship between these categorial systems in terms of the antipodal neurophysiological, behavioral, and decision (cognitive) functions that engender normal and addictive responding. However, a case may be made for construing several components of the impulsive and executive systems depicted in the model as categories (elements) of additional systems that are concerned with the metacognitive control of behavior. Hence, this paper proposes a category-based structure for understanding the effects on behavior of CNDS, which includes not only the impulsive and executive systems of the basic model but a superordinate level of reflective or rational decision-making. Following recent developments in the modeling of cognitive control which contrasts Type 1 (rapid, autonomous, parallel) processing with Type 2 (slower, computationally demanding, sequential) processing, the proposed model incorporates an arena in which the potentially conflicting imperatives of impulsive and executive systems are examined and from which a more appropriate behavioral response than impulsive choice emerges. This configuration suggests a forum in which the interaction of picoeconomic interests, which provide a cognitive dimension for CNDS, can be conceptualized. This proposition is examined in light of the resolution of conflict by means of bundling. PMID:26925004

The use of the Wigner Distribution to analyze structural impulse responses

NASA Technical Reports Server (NTRS)

Wahl, T. J.; Bolton, J. S.

1990-01-01

In this paper it is argued that the time-frequency analysis of structural impulse responses may be used to reveal the wave types carrying significant energy through a structure. Since each wave type is characterized by its own dispersion relation, each wave type may be associated with particular features appearing in the time-frequency domain representation of an impulse response. Here the Wigner Distribution is introduced as a means for obtaining appropriate time-frequency representations of impulse responses. Practical aspects of the calculation of the Wigner Distribution are discussed and examples of its application to the analysis of structural impulse responses are given. These examples will show that the Wigner Distribution may be conveniently used to distinguish between the contributions of various waves types to a total structural response.

Influence of impulsiveness on emotional modulation of response inhibition: An ERP study.

PubMed

Messerotti Benvenuti, Simone; Sarlo, Michela; Buodo, Giulia; Mento, Giovanni; Palomba, Daniela

2015-10-01

To examine how impulsiveness influences the emotional modulation of behavioral and neural correlates of response inhibition. Twenty-nine healthy individuals scoring high (HI, N=16) or low (LI, N=13) on motor impulsiveness performed an emotional Go/Nogo task, including the presentation of pleasant, neutral and unpleasant pictures. Behavioral [reaction times (RTs), accuracy to Go and Nogo trials] and neural (Nogo-N2 and Nogo-P3) correlates of response inhibition were compared between HI and LI groups. Larger Nogo-P3 was found for emotional than neutral stimuli in HI relative to LI group. Faster RTs to Go stimuli and lower accuracy to Nogo stimuli were correlated with larger Nogo-P3 in HI, but not LI, group. No significant interactions between emotion content and impulsiveness for Nogo-N2 and behavioral measures were noted. Impulsiveness influences the emotional modulation of response inhibition by potentiating the response tendencies evoked by the emotional stimuli. Accordingly, high impulsive individuals may need an increased and/or more effortful response inhibition in order to counteract the prepotent tendency to respond elicited by the combination of high trait impulsiveness and high emotional arousal. The present study suggests the importance to examine how pathological impulsiveness may interact with emotional arousal in modulating response inhibition. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Deriving a dosage-response relationship for community response to high-energy impulsive noise

NASA Technical Reports Server (NTRS)

Fidell, Sanford; Pearsons, Karl S.

1994-01-01

The inability to systematically predict community response to exposure to sonic booms (and other high energy impulsive sounds) is a major impediment to credible analyses of the environmental effects of supersonic flight operations. Efforts to assess community response to high energy impulsive sounds are limited in at least two important ways. First, a paucity of appropriate empirical data makes it difficult to infer a dosage-response relationship by means similar to those used in the case of general transportation noise. Second, it is unclear how well the 'equal energy hypothesis' (the notion that duration, number, and level of individual events are directly interchangeable determinants of annoyance) applies to some forms of impulsive noise exposure. Some of the issues currently under consideration by a CHABA working group addressing these problems are discussed. These include means for applying information gained in controlled exposure studies about different rates of growth of annoyance with impulsive and non-impulsive sound exposure levels, and strategies for developing a dosage-response relationship in a data-poor area.

High speed cross-amplitude modulation in concatenated SOA-EAM-SOA.

PubMed

Cleary, Ciaran S; Manning, Robert J

2012-06-18

We observe a near-ideal high speed amplitude impulse response in an SOA-EAM-SOA configuration under optimum conditions. Full amplitude recovery times as low as 10 ps with modulation depths of 70% were observed in pump-probe measurements. System behavior could be controlled by the choice of signal wavelength, SOA current biases and EAM reverse bias voltages. Experimental data and impulse response modelling indicated that the slow tail in the gain response of first SOA was negated by a combination of cross-absorption modulation between pump and modulated CW probe, and self-gain modulation of the modulated CW probe in both the EAM and second SOA.

MATLAB/Simulink Pulse-Echo Ultrasound System Simulator Based on Experimentally Validated Models.

PubMed

Kim, Taehoon; Shin, Sangmin; Lee, Hyongmin; Lee, Hyunsook; Kim, Heewon; Shin, Eunhee; Kim, Suhwan

2016-02-01

A flexible clinical ultrasound system must operate with different transducers, which have characteristic impulse responses and widely varying impedances. The impulse response determines the shape of the high-voltage pulse that is transmitted and the specifications of the front-end electronics that receive the echo; the impedance determines the specification of the matching network through which the transducer is connected. System-level optimization of these subsystems requires accurate modeling of pulse-echo (two-way) response, which in turn demands a unified simulation of the ultrasonics and electronics. In this paper, this is realized by combining MATLAB/Simulink models of the high-voltage transmitter, the transmission interface, the acoustic subsystem which includes wave propagation and reflection, the receiving interface, and the front-end receiver. To demonstrate the effectiveness of our simulator, the models are experimentally validated by comparing the simulation results with the measured data from a commercial ultrasound system. This simulator could be used to quickly provide system-level feedback for an optimized tuning of electronic design parameters.

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

NASA Astrophysics Data System (ADS)

Pei, Yongzhen; Liu, Shaoying; Li, Changguo

2009-06-01

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

IMPULSE Highlights for recent experiments at the Advanced Photon Source (2/9-2/18 2014)

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

Jensen, Brian J.

2014-03-18

This report is a presentation, with slides noting, Over 40 experiments were completed during this run using X-ray imaging on the IMPULSE system at Sector 32 IDB; Summary of new experiments: Idealized sphere compaction – Capture progression of dynamic densification through an idealized system on 0.500 mm borosilicate glass spheres (Slide 1); Detonator and EBW Imaging Experiments on IMPULSE – First time HE was intentionally detonated at APS (Slide 2); Spall and high strain rate crack nucleation/propagation in PMMA – PCI data is providing new and unique insights for model validation (Slide 3); Fiber composite for armor applications was studiedmore » under ballistic impact of Dyneema (Collaboration with Army Research Laboratory) (Slide 4). Summary of on-going experiments; Crack propagation in vitreous carbon – observed crack motion and caustic; Jet formation experiments on large grain cerium to examine phase dependent strength; Ballistic impact of Comp-B and TNT to examine thermo-mechanical response in-situ with various penetrator geometries to vary shear concentration. Other efforts: IMPULSE system moved and installed in Sector 35 (DCS). This includes the 4-frame X-ray detection system, 4- channel PDV, and other gun diagnostics; New remotely operated mobile IMPULSE structure in fabrication – to be delivered to APS in April; 4 Mini-VISAR Systems and 4-channel PDV installed in DCS instrumentation room with all associated diagnostics.« less

Identification of Experimental Unsteady Aerodynamic Impulse Responses

NASA Technical Reports Server (NTRS)

Silva, Walter A.; Piatak, David J.; Scott, Robert C.

2003-01-01

The identification of experimental unsteady aerodynamic impulse responses using the Oscillating Turntable (OTT) at NASA Langley's Transonic Dynamics Tunnel (TDT) is described. Results are presented for two configurations: a Rigid Semispan Model (RSM) and a rectangular wing with a supercritical airfoil section. Both models were used to acquire unsteady pressure data due to pitching oscillations on the OTT. A deconvolution scheme involving a step input in pitch and the resultant step response in pressure, for several pressure transducers, is used to identify the pressure impulse responses. The identified impulse responses are then used to predict the pressure response due to pitching oscillations at several frequencies. Comparisons with the experimental data are presented.

A negative relationship between ventral striatal loss anticipation response and impulsivity in borderline personality disorder.

PubMed

Herbort, Maike C; Soch, Joram; Wüstenberg, Torsten; Krauel, Kerstin; Pujara, Maia; Koenigs, Michael; Gallinat, Jürgen; Walter, Henrik; Roepke, Stefan; Schott, Björn H

2016-01-01

Patients with borderline personality disorder (BPD) frequently exhibit impulsive behavior, and self-reported impulsivity is typically higher in BPD patients when compared to healthy controls. Previous functional neuroimaging studies have suggested a link between impulsivity, the ventral striatal response to reward anticipation, and prediction errors. Here we investigated the striatal neural response to monetary gain and loss anticipation and their relationship with impulsivity in 21 female BPD patients and 23 age-matched female healthy controls using functional magnetic resonance imaging (fMRI). Participants performed a delayed monetary incentive task in which three categories of objects predicted a potential gain, loss, or neutral outcome. Impulsivity was assessed using the Barratt Impulsiveness Scale (BIS-11). Compared to healthy controls, BPD patients exhibited significantly reduced fMRI responses of the ventral striatum/nucleus accumbens (VS/NAcc) to both reward-predicting and loss-predicting cues. BIS-11 scores showed a significant positive correlation with the VS/NAcc reward anticipation responses in healthy controls, and this correlation, while also nominally positive, failed to reach significance in BPD patients. BPD patients, on the other hand, exhibited a significantly negative correlation between ventral striatal loss anticipation responses and BIS-11 scores, whereas this correlation was significantly positive in healthy controls. Our results suggest that patients with BPD show attenuated anticipation responses in the VS/NAcc and, furthermore, that higher impulsivity in BPD patients might be related to impaired prediction of aversive outcomes.

Distinguishing between learning and motivation in behavioral tests of the reinforcement sensitivity theory of personality.

PubMed

Smillie, Luke D; Dalgleish, Len I; Jackson, Chris J

2007-04-01

According to Gray's (1973) Reinforcement Sensitivity Theory (RST), a Behavioral Inhibition System (BIS) and a Behavioral Activation System (BAS) mediate effects of goal conflict and reward on behavior. BIS functioning has been linked with individual differences in trait anxiety and BAS functioning with individual differences in trait impulsivity. In this article, it is argued that behavioral outputs of the BIS and BAS can be distinguished in terms of learning and motivation processes and that these can be operationalized using the Signal Detection Theory measures of response-sensitivity and response-bias. In Experiment 1, two measures of BIS-reactivity predicted increased response-sensitivity under goal conflict, whereas one measure of BAS-reactivity predicted increased response-sensitivity under reward. In Experiment 2, two measures of BIS-reactivity predicted response-bias under goal conflict, whereas a measure of BAS-reactivity predicted motivation response-bias under reward. In both experiments, impulsivity measures did not predict criteria for BAS-reactivity as traditionally predicted by RST.

Impulsive traits and unplanned suicide attempts predict exaggerated prefrontal response to angry faces in the elderly

PubMed Central

Vanyukov, Polina M.; Szanto, Katalin; Siegle, Greg J.; Hallquist, Michael N.; Reynolds, Charles F.; Aizenstein, Howard J.; Dombrovski, Alexandre Y.

2015-01-01

Objectives Abnormal responses to social stimuli are seen in people vulnerable to suicidal behavior, indicating possible disruptions in the neural circuitry mediating the interpretation of socio-emotional cues. These disruptions have not been empirically related to psychological and cognitive pathways to suicide. In the present study of older suicide attempters, we examined neural responses to emotional faces and their relationship to impulsivity, one of the components of the suicidal diathesis. Methods Using functional magnetic resonance imaging, we recorded neuro-hemodynamic responses to angry faces in a carefully-characterized sample of 18 depressed elderly with history of suicide attempts, 13 depressed non-suicidal patients, and 18 healthy individuals, all aged 60+. Impulsivity was assessed with the Social Problem Solving Inventory Impulsivity/Carelessness Style subscale and Barratt Impulsiveness Scale. The Suicide Intent Scale planning subscale was used to describe the degree of planning associated with the most lethal attempt. Results Depression and history of attempted suicide were not associated with neural responses to angry faces, failing to replicate earlier studies. Higher impulsivity, however, predicted exaggerated responses to angry faces in fronto-opercular and dorsomedial prefrontal cortex (pcorr < .05). Poorly planned suicide attempts also predicted increased fronto-opercular responses. Results were robust to effects of medication exposure, comorbid anxiety and addiction, severity of depression, burden of physical illness, and possible brain injury from suicide attempts. Conclusions Impulsive traits and history of unplanned suicide attempts partly explain the heterogeneity in neural responses to angry faces in depressed elderly. Displays of social emotion command excessive cortical processing in impulsive suicide attempters. PMID:25529800

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.

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.

Estimation of Instantaneous Gas Exchange in Flow-Through Respirometry Systems: A Modern Revision of Bartholomew's Z-Transform Method

PubMed Central

Pendar, Hodjat; Socha, John J.

2015-01-01

Flow-through respirometry systems provide accurate measurement of gas exchange over long periods of time. However, these systems have limitations in tracking rapid changes. When an animal infuses a metabolic gas into the respirometry chamber in a short burst, diffusion and airflow in the chamber gradually alter the original signal before it arrives at the gas analyzer. For single or multiple bursts, the recorded signal is smeared or mixed, which may result in dramatically altered recordings compared to the emitted signal. Recovering the original metabolic signal is a difficult task because of the inherent ill conditioning problem. Here, we present two new methods to recover the fast dynamics of metabolic patterns from recorded data. We first re-derive the equations of the well-known Z-transform method (ZT method) to show the source of imprecision in this method. Then, we develop a new model of analysis for respirometry systems based on the experimentally determined impulse response, which is the response of the system to a very short unit input. As a result, we present a major modification of the ZT method (dubbed the ‘EZT method’) by using a new model for the impulse response, enhancing its precision to recover the true metabolic signals. The second method, the generalized Z-transform (GZT) method, was then developed by generalizing the EZT method; it can be applied to any flow-through respirometry system with any arbitrary impulse response. Experiments verified that the accuracy of recovering the true metabolic signals is significantly improved by the new methods. These new methods can be used more broadly for input estimation in variety of physiological systems. PMID:26466361

The Role of Habituation and Sensitization in Understanding the Annoyance of Community Exposures to Impulsive Noise

DTIC Science & Technology

2009-05-15

an orienting re- sponse followed by a defense response at 64 dBA ( impulse ). The 80 dB ERDC/CERL TR-09-14 25 impulses produced by the small firearm...literature, shorter response latencies are generally attributed to a greater degree of arousal. With impulsive sounds repeated in rapid succession...ERDC–CERL, SERDP-funded project focusing on evaluating responses to military noise. The research team’s decision was based on time burden

Attentional impulsivity in binge eating disorder modulates response inhibition performance and frontal brain networks.

PubMed

Hege, M A; Stingl, K T; Kullmann, S; Schag, K; Giel, K E; Zipfel, S; Preissl, H

2015-02-01

A subgroup of overweight and obese people is characterized by binge eating disorder (BED). Increased impulsivity has been suggested to cause binge eating and subsequent weight gain. In the current study, neuronal correlates of increased impulsivity in binge eating disorder during behavioral response inhibition were investigated. Magnetic brain activity and behavioral responses of 37 overweight and obese individuals with and without diagnosed BED were recorded while performing a food-related visual go-nogo task. Trait impulsivity was assessed with the Barratt Impulsiveness Scale (BIS-11). Specifically, increased attentional impulsiveness (a subscale of the BIS-11) in BED was related to decreased response inhibition performance and hypoactivity in the prefrontal control network, which was activated when response inhibition was required. Furthermore, participants with BED showed a trend for a food-specific inhibition performance decline. This was possibly related to the absence of a food-specific activity increase in the prefrontal control network in BED, as observed in the control group. In addition, an increase in activity related to the actual button press during prepotent responses and alterations in visual processing were observed. Our results suggest an attentional impulsiveness-related attenuation in response inhibition performance in individuals with BED. This might have been related to increased reward responsiveness and limited resources to activate the prefrontal control network involved in response inhibition. Our results substantiate the importance of neuronal markers for investigating prevention and treatment of obesity, especially in specific subgroups at risk such as BED.

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.

Development of Aeroservoelastic Analytical Models and Gust Load Alleviation Control Laws of a SensorCraft Wind-Tunnel Model Using Measured Data

NASA Technical Reports Server (NTRS)

Silva, Walter A.; Vartio, Eric; Shimko, Anthony; Kvaternik, Raymond G.; Eure, Kenneth W.; Scott,Robert C.

2007-01-01

Aeroservoelastic (ASE) analytical models of a SensorCraft wind-tunnel model are generated using measured data. The data was acquired during the ASE wind-tunnel test of the HiLDA (High Lift-to-Drag Active) Wing model, tested in the NASA Langley Transonic Dynamics Tunnel (TDT) in late 2004. Two time-domain system identification techniques are applied to the development of the ASE analytical models: impulse response (IR) method and the Generalized Predictive Control (GPC) method. Using measured control surface inputs (frequency sweeps) and associated sensor responses, the IR method is used to extract corresponding input/output impulse response pairs. These impulse responses are then transformed into state-space models for use in ASE analyses. Similarly, the GPC method transforms measured random control surface inputs and associated sensor responses into an AutoRegressive with eXogenous input (ARX) model. The ARX model is then used to develop the gust load alleviation (GLA) control law. For the IR method, comparison of measured with simulated responses are presented to investigate the accuracy of the ASE analytical models developed. For the GPC method, comparison of simulated open-loop and closed-loop (GLA) time histories are presented.

Development of Aeroservoelastic Analytical Models and Gust Load Alleviation Control Laws of a SensorCraft Wind-Tunnel Model Using Measured Data

NASA Technical Reports Server (NTRS)

Silva, Walter A.; Shimko, Anthony; Kvaternik, Raymond G.; Eure, Kenneth W.; Scott, Robert C.

2006-01-01

Aeroservoelastic (ASE) analytical models of a SensorCraft wind-tunnel model are generated using measured data. The data was acquired during the ASE wind-tunnel test of the HiLDA (High Lift-to-Drag Active) Wing model, tested in the NASA Langley Transonic Dynamics Tunnel (TDT) in late 2004. Two time-domain system identification techniques are applied to the development of the ASE analytical models: impulse response (IR) method and the Generalized Predictive Control (GPC) method. Using measured control surface inputs (frequency sweeps) and associated sensor responses, the IR method is used to extract corresponding input/output impulse response pairs. These impulse responses are then transformed into state-space models for use in ASE analyses. Similarly, the GPC method transforms measured random control surface inputs and associated sensor responses into an AutoRegressive with eXogenous input (ARX) model. The ARX model is then used to develop the gust load alleviation (GLA) control law. For the IR method, comparison of measured with simulated responses are presented to investigate the accuracy of the ASE analytical models developed. For the GPC method, comparison of simulated open-loop and closed-loop (GLA) time histories are presented.

Reduced-Order Models Based on Linear and Nonlinear Aerodynamic Impulse Responses

NASA Technical Reports Server (NTRS)

Silva, Walter A.

1999-01-01

This paper discusses a method for the identification and application of reduced-order models based on linear and nonlinear aerodynamic impulse responses. The Volterra theory of nonlinear systems and an appropriate kernel identification technique are described. Insight into the nature of kernels is provided by applying the method to the nonlinear Riccati equation in a non-aerodynamic application. The method is then applied to a nonlinear aerodynamic model of RAE 2822 supercritical airfoil undergoing plunge motions using the CFL3D Navier-Stokes flow solver with the Spalart-Allmaras turbulence model. Results demonstrate the computational efficiency of the technique.

Reduced Order Models Based on Linear and Nonlinear Aerodynamic Impulse Responses

NASA Technical Reports Server (NTRS)

Silva, Walter A.

1999-01-01

This paper discusses a method for the identification and application of reduced-order models based on linear and nonlinear aerodynamic impulse responses. The Volterra theory of nonlinear systems and an appropriate kernel identification technique are described. Insight into the nature of kernels is provided by applying the method to the nonlinear Riccati equation in a non-aerodynamic application. The method is then applied to a nonlinear aerodynamic model of an RAE 2822 supercritical airfoil undergoing plunge motions using the CFL3D Navier-Stokes flow solver with the Spalart-Allmaras turbulence model. Results demonstrate the computational efficiency of the technique.

Linear ordinary differential equations with constant coefficients. Revisiting the impulsive response method using factorization

NASA Astrophysics Data System (ADS)

Camporesi, Roberto

2011-06-01

We present an approach to the impulsive response method for solving linear constant-coefficient ordinary differential equations based on the factorization of the differential operator. The approach is elementary, we only assume a basic knowledge of calculus and linear algebra. In particular, we avoid the use of distribution theory, as well as of the other more advanced approaches: Laplace transform, linear systems, the general theory of linear equations with variable coefficients and the variation of constants method. The approach presented here can be used in a first course on differential equations for science and engineering majors.

ACIRF user's guide: Theory and examples

NASA Astrophysics Data System (ADS)

Dana, Roger A.

1989-12-01

Design and evaluation of radio frequency systems that must operate through ionospheric disturbances resulting from high altitude nuclear detonations requires an accurate channel model. This model must include the effects of high gain antennas that may be used to receive the signals. Such a model can then be used to construct realizations of the received signal for use in digital simulations of trans-ionospheric links or for use in hardware channel simulators. The FORTRAN channel model ACIRF (Antenna Channel Impulse Response Function) generates random realizations of the impulse response function at the outputs of multiple antennas. This user's guide describes the FORTRAN program ACIRF (version 2.0) that generates realizations of channel impulse response functions at the outputs of multiple antennas with arbitrary beamwidths, pointing angles, and relatives positions. This channel model is valid under strong scattering conditions when Rayleigh fading statistics apply. Both frozen-in and turbulent models for the temporal fluctuations are included in this version of ACIRF. The theory of the channel model is described and several examples are given.

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

Electronic Imaging

DTIC Science & Technology

1991-11-01

Tilted Rough Disc," Donald J. Schertler and Nicholas George "Image Deblurring for Multiple-Point Impulse Responses," Bryan J. Stossel and Nicholas George...Rough Disc Donald J. Schertler Nicholas George Image Deblurring for Multiple-Point Impulse Bryan J. Stossel Responses Nicholas George z 0 zw V) w LU 0...number of impulses present in the degradation. IMAGE DEBLURRING FOR MULTIPLE-POINT IMPULSE RESPONSESt Bryan J. Stossel Nicholas George Institute of Optics

Real-Time Decision Making and Aggressive Behavior in Youth: A Heuristic Model of Response Evaluation and Decision (RED)

PubMed Central

Fontaine, Reid Griffith; Dodge, Kenneth A.

2009-01-01

Considerable scientific and intervention attention has been paid to judgment and decision-making systems associated with aggressive behavior in youth. However, most empirical studies have investigated social-cognitive correlates of stable child and adolescent aggressiveness, and less is known about real-time decision making to engage in aggressive behavior. A model of real-time decision making must incorporate both impulsive actions and rational thought. The present paper advances a process model (response evaluation and decision; RED) of real-time behavioral judgments and decision making in aggressive youths with mathematic representations that may be used to quantify response strength. These components are a heuristic to describe decision making, though it is doubtful that individuals always mentally complete these steps. RED represents an organization of social–cognitive operations believed to be active during the response decision step of social information processing. The model posits that RED processes can be circumvented through impulsive responding. This article provides a description and integration of thoughtful, rational decision making and nonrational impulsivity in aggressive behavioral interactions. PMID:20802851

Real-Time Decision Making and Aggressive Behavior in Youth: A Heuristic Model of Response Evaluation and Decision (RED).

PubMed

Fontaine, Reid Griffith; Dodge, Kenneth A

2006-11-01

Considerable scientific and intervention attention has been paid to judgment and decision-making systems associated with aggressive behavior in youth. However, most empirical studies have investigated social-cognitive correlates of stable child and adolescent aggressiveness, and less is known about real-time decision making to engage in aggressive behavior. A model of real-time decision making must incorporate both impulsive actions and rational thought. The present paper advances a process model (response evaluation and decision; RED) of real-time behavioral judgments and decision making in aggressive youths with mathematic representations that may be used to quantify response strength. These components are a heuristic to describe decision making, though it is doubtful that individuals always mentally complete these steps. RED represents an organization of social-cognitive operations believed to be active during the response decision step of social information processing. The model posits that RED processes can be circumvented through impulsive responding. This article provides a description and integration of thoughtful, rational decision making and nonrational impulsivity in aggressive behavioral interactions.

Impulsive traits and unplanned suicide attempts predict exaggerated prefrontal response to angry faces in the elderly.

PubMed

Vanyukov, Polina M; Szanto, Katalin; Siegle, Greg J; Hallquist, Michael N; Reynolds, Charles F; Aizenstein, Howard J; Dombrovski, Alexandre Y

2015-08-01

Abnormal responses to social stimuli are seen in people vulnerable to suicidal behavior, indicating possible disruptions in the neural circuitry mediating the interpretation of socioemotional cues. These disruptions have not been empirically related to psychological and cognitive pathways to suicide. In the present study of older suicide attempters, we examined neural responses to emotional faces and their relationship to impulsivity, one of the components of the suicidal diathesis. Using functional magnetic resonance imaging, we recorded neurohemodynamic responses to angry faces in a carefully characterized sample of 18 depressed elderly with history of suicide attempts, 13 depressed nonsuicidal patients, and 18 healthy individuals, all aged 60+. Impulsivity was assessed with the Social Problem Solving Inventory Impulsivity/Carelessness Style subscale and Barratt Impulsiveness Scale. The Suicide Intent Scale planning subscale was used to describe the degree of planning associated with the most lethal attempt. Depression and history of attempted suicide were not associated with neural responses to angry faces, failing to replicate earlier studies. Higher impulsivity, however, predicted exaggerated responses to angry faces in fronto-opercular and dorsomedial prefrontal cortex (pcorr <0.05). Poorly planned suicide attempts also predicted increased fronto-opercular responses. Results were robust to effects of medication exposure, comorbid anxiety and addiction, severity of depression, burden of physical illness, and possible brain injury from suicide attempts. Impulsive traits and history of unplanned suicide attempts partly explain the heterogeneity in neural responses to angry faces in depressed elderly. Displays of social emotion command excessive cortical processing in impulsive suicide attempters. Copyright © 2015 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.

Synthesis of Natural Electric and Magnetic Time Series Using Impulse Responses of Inter-station Transfer Functions and a Reference

NASA Astrophysics Data System (ADS)

Wang, H.; Cheng, J.

2017-12-01

A method to Synthesis natural electric and magnetic Time series is proposed whereby the time series of local site are derived using an Impulse Response and a reference (STIR). The method is based on the assumption that the external source of magnetic fields are uniform, and the electric and magnetic fields acquired at the surface satisfy a time-independent linear relation in frequency domain.According to the convolution theorem, we can synthesize natural electric and magnetic time series using the impulse responses of inter-station transfer functions with a reference. Applying this method, two impulse responses need to be estimated: the quasi-MT impulse response tensor and the horizontal magnetic impulse response tensor. These impulse response tensors relate the local horizontal electric and magnetic components with the horizontal magnetic components at a reference site, respectively. Some clean segments of times series are selected to estimate impulse responses by using least-square (LS) method. STIR is similar with STIN (Wang, 2017), but STIR does not need to estimate the inter-station transfer functions, and the synthesized data are more accurate in high frequency, where STIN fails when the inter-station transfer functions are contaminated severely. A test with good quality of MT data shows that synthetic time-series are similar to natural electric and magnetic time series. For contaminated AMT example, when this method is used to remove noise present at the local site, the scatter of MT sounding curves are clear reduced, and the data quality are improved. *This work is funded by National Key R&D Program of China(2017YFC0804105),National Natural Science Foundation of China (41604064, 51574250), State Key Laboratory of Coal Resources and Safe Mining ,China University of Mining & Technology,(SKLCRSM16DC09)

Ethanol induces impulsive-like responding in a delay-of-reward operant choice procedure: impulsivity predicts autoshaping.

PubMed

Tomie, A; Aguado, A S; Pohorecky, L A; Benjamin, D

1998-10-01

Autoshaping conditioned responses (CRs) are reflexive and targeted motor responses expressed as a result of experience with reward. To evaluate the hypothesis that autoshaping may be a form of impulsive responding, within-subjects correlations between performance on autoshaping and impulsivity tasks were assessed in 15 Long-Evans hooded rats. Autoshaping procedures [insertion of retractable lever conditioned stimulus (CS) followed by the response-independent delivery of food (US)] were followed by testing for impulsive-like responding in a two-choice lever-press operant delay-of-reward procedure (immediate small food reward versus delayed large food reward). Delay-of-reward functions revealed two distinct subject populations. Subjects in the Sensitive group (n=7) were more impulsive-like, increasing immediate reward choices at longer delays for large reward, while those in the Insensitive group (n=8) responded predominantly on only one lever. During the prior autoshaping phase, the Sensitive group had performed more autoshaping CRs, and correlations revealed that impulsive subjects acquired the autoshaping CR in fewer trials. In the Sensitive group, acute injections of ethanol (0, 0.25, 0.50, 1.00, 1.50 g/kg) given immediately before delay-of-reward sessions yielded an inverted U-shaped dose-response curve with increased impulsivity induced by the 0.25, 0.50, and 1.00 g/kg doses of ethanol, while choice strategy of the Insensitive group was not influenced by ethanol dose. Ethanol induced impulsive-like responding only in rats that were flexible in their response strategy (Sensitive group), and this group also performed more autoshaping CRs. Data support the hypothesis that autoshaping and impulsivity are linked.

Properties of Zero-Free Transfer Function Matrices

NASA Astrophysics Data System (ADS)

D. O. Anderson, Brian; Deistler, Manfred

Transfer functions of linear, time-invariant finite-dimensional systems with more outputs than inputs, as arise in factor analysis (for example in econometrics), have, for state-variable descriptions with generic entries in the relevant matrices, no finite zeros. This paper gives a number of characterizations of such systems (and indeed square discrete-time systems with no zeros), using state-variable, impulse response, and matrix-fraction descriptions. Key properties include the ability to recover the input values at any time from a bounded interval of output values, without any knowledge of an initial state, and an ability to verify the no-zero property in terms of a property of the impulse response coefficient matrices. Results are particularized to cases where the transfer function matrix in question may or may not have a zero at infinity or a zero at zero.

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.

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

PubMed

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

2012-08-01

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

An examination of the relationship between measures of impulsivity and risky simulated driving amongst young drivers.

PubMed

Hatfield, Julie; Williamson, Ann; Kehoe, E James; Prabhakharan, Prasannah

2017-06-01

The risky driving of young drivers may owe in part to youthful motivations (such as experience-seeking, authority rebellion, desire for peer approval) combined with incompletely developed impulse control. Although self-reported impulsiveness has been positively associated with self-reports of risky driving, results based on objective measures of response inhibition (e.g., Go/No-go tasks) have been inconclusive. The present study examined interrelationships between measures of response inhibition, self-report impulsiveness scales, and responses to events during a simulated drive that were designed to detect impulsive, unsafe behaviours (e.g., turning across on-coming traffic). Participants were 72 first-year Psychology students. More speeding and "Unsafe" responding to critical events during simulated driving were associated with poorer impulse control as assessed by commission errors during a Go/No-Go task. These results consolidate evidence for a relationship between impulse control and risky driving amongst young drivers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sensitivity of combustion and ignition characteristics of the solid-fuel charge of the microelectromechanical system of a microthruster to macrokinetic and design parameters

NASA Astrophysics Data System (ADS)

Futko, S. I.; Ermolaeva, E. M.; Dobrego, K. V.; Bondarenko, V. P.; Dolgii, L. N.

2012-07-01

We have developed a sensitivity analysis permitting effective estimation of the change in the impulse responses of a microthrusters and in the ignition characteristics of the solid-fuel charge caused by the variation of the basic macrokinetic parameters of the mixed fuel and the design parameters of the microthruster's combustion chamber. On the basis of the proposed sensitivity analysis, we have estimated the spread of both the propulsive force and impulse and the induction period and self-ignition temperature depending on the macrokinetic parameters of combustion (pre-exponential factor, activation energy, density, and heat content) of the solid-fuel charge of the microthruster. The obtained results can be used for rapid and effective estimation of the spread of goal functions to provide stable physicochemical characteristics and impulse responses of solid-fuel mixtures in making and using microthrusters.

Aurally-adequate time-frequency analysis for scattered sound in auditoria

NASA Astrophysics Data System (ADS)

Norris, Molly K.; Xiang, Ning; Kleiner, Mendel

2005-04-01

The goal of this work was to apply an aurally-adequate time-frequency analysis technique to the analysis of sound scattering effects in auditoria. Time-frequency representations were developed as a motivated effort that takes into account binaural hearing, with a specific implementation of interaural cross-correlation process. A model of the human auditory system was implemented in the MATLAB platform based on two previous models [A. Härmä and K. Palomäki, HUTear, Espoo, Finland; and M. A. Akeroyd, A. Binaural Cross-correlogram Toolbox for MATLAB (2001), University of Sussex, Brighton]. These stages include proper frequency selectivity, the conversion of the mechanical motion of the basilar membrane to neural impulses, and binaural hearing effects. The model was then used in the analysis of room impulse responses with varying scattering characteristics. This paper discusses the analysis results using simulated and measured room impulse responses. [Work supported by the Frank H. and Eva B. Buck Foundation.

Probing Thermomechanics at the Nanoscale: Impulsively Excited Pseudosurface Acoustic Waves in Hypersonic Phononic Crystals

PubMed Central

2011-01-01

High-frequency surface acoustic waves can be generated by ultrafast laser excitation of nanoscale patterned surfaces. Here we study this phenomenon in the hypersonic frequency limit. By modeling the thermomechanics from first-principles, we calculate the system’s initial heat-driven impulsive response and follow its time evolution. A scheme is introduced to quantitatively access frequencies and lifetimes of the composite system’s excited eigenmodes. A spectral decomposition of the calculated response on the eigemodes of the system reveals asymmetric resonances that result from the coupling between surface and bulk acoustic modes. This finding allows evaluation of impulsively excited pseudosurface acoustic wave frequencies and lifetimes and expands our understanding of the scattering of surface waves in mesoscale metamaterials. The model is successfully benchmarked against time-resolved optical diffraction measurements performed on one-dimensional and two-dimensional surface phononic crystals, probed using light at extreme ultraviolet and near-infrared wavelengths. PMID:21910426

Modeling the response of a monopulse radar to impulsive jamming signals using the Block Oriented System Simulator (BOSS)

NASA Astrophysics Data System (ADS)

Long, Jeffrey K.

1989-09-01

This theses developed computer models of two types of amplitude comparison monopulse processors using the Block Oriented System Simulation (BOSS) software package and to determine the response to these models to impulsive input signals. This study was an effort to determine the susceptibility of monopulse tracking radars to impulsing jamming signals. Two types of amplitude comparison monopulse receivers were modeled, one using logarithmic amplifiers and the other using automatic gain control for signal normalization. Simulations of both types of systems were run under various conditions of gain or frequency imbalance between the two receiver channels. The resulting errors from the imbalanced simulations were compared to the outputs of similar, baseline simulations which had no electrical imbalances. The accuracy of both types of processors was directly affected by gain or frequency imbalances in their receiver channels. In most cases, it was possible to generate both positive and negative angular errors, dependent upon the type and degree of mismatch between the channels. The system most susceptible to induced errors was a frequency imbalanced processor which used AGC circuitry. Any errors introduced will be a function of the degree of mismatch between the channels and therefore would be difficult to exploit reliably.

Can't stop the craving: the effect of impulsivity on cue-elicited craving for alcohol in heavy and light social drinkers.

PubMed

Papachristou, Harilaos; Nederkoorn, Chantal; Havermans, Remco; van der Horst, Martje; Jansen, Anita

2012-01-01

A robust finding in the alcohol literature is that heavy and alcohol-dependent drinkers show stronger reactions to alcohol-related cues than light drinkers. However, there are individual differences in the degree of cue-elicited craving. Personality factors appear to be involved in cue reactivity and impulsivity is a possible candidate. The aim of the present study was to examine the role of different aspects of impulsivity in heavy drinking and alcohol cue reactivity in social drinkers. Participants were heavy (n = 13) and light (n = 29) social drinkers who were exposed to neutral and alcohol-related stimuli during a single laboratory session. Trait impulsivity, response inhibition, and sensitivity to reward were assessed with the Barratt Impulsiveness Scale (BIS-11), the Stop Signal Task, and the Card-Arranging Reward Responsivity Objective Test, respectively. Heavy drinkers scored higher on trait impulsivity (BIS-11) than light drinkers. In addition, heavy drinkers reported elevated levels of craving for alcohol, but both in light and heavy drinkers, craving increased equally after exposure to alcohol cues. Impulsivity appeared to moderate this relation: heavy drinkers with ineffective response inhibition showed more craving to alcohol cues, compared to heavy drinkers with adequate response inhibition. In light drinkers, response inhibition did not influence craving to alcohol cues. Different aspects of impulsivity are involved in heavy drinking and perhaps motivate alcohol consumption in a variety of ways. Having a deficient response inhibition appears to be a risk factor for heavy drinkers because it is associated with increased craving to alcohol cues.

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.

Modeling Study of the Geospace System Response to the Solar Wind Dynamic Pressure Enhancement on 17 March 2015

NASA Astrophysics Data System (ADS)

Ozturk, D. S.; Zou, S.; Ridley, A. J.; Slavin, J. A.

2018-04-01

The global magnetosphere-ionosphere-thermosphere system is intrinsically coupled and susceptible to external drivers such as solar wind dynamic pressure enhancements. In order to understand the large-scale dynamic processes in the magnetosphere-ionosphere-thermosphere system due to the compression from the solar wind, the 17 March 2015 sudden commencement was studied in detail using global numerical models. This storm was one of the most geoeffective events of the solar cycle 24 with a minimum Dst of -222 nT. The Wind spacecraft recorded a 10-nPa increment in the solar wind dynamic pressure, while the interplanetary magnetic field BZ became further northward. The University of Michigan Block-Adaptive-Tree Solar wind Roe-type Upwind Scheme global magnetohydrodynamic code was utilized to study the generation and propagation of perturbations associated with the compression of the magnetosphere system. In addition, the high-resolution electric potential and auroral power output from the magnetohydrodynamic model was used to drive the global ionosphere-thermosphere model to investigate the ionosphere-thermosphere system response to pressure enhancement. During the compression, the electric potentials and convection patterns in the polar ionosphere were significantly altered when the preliminary impulse and main impulse field-aligned currents moved from dayside to nightside. As a result of enhanced frictional heating, plasma and neutral temperatures increased at the locations where the flow speeds were enhanced, whereas the electron density dropped at these locations. In particular, the region between the preliminary impulse and main impulse field-aligned currents experienced the most significant heating with 1000-K ion temperature increase and 20-K neutral temperature increase within 2 min. Comparison of the simulation results with the Poker Flat Incoherent Scatter Radar observations showed reasonable agreements despite underestimated magnitudes.

Volumetric Security Alarm Based on a Spherical Ultrasonic Transducer Array

NASA Astrophysics Data System (ADS)

Sayin, Umut; Scaini, Davide; Arteaga, Daniel

Most of the existent alarm systems depend on physical or visual contact. The detection area is often limited depending on the type of the transducer, creating blind spots. Our proposition is a truly volumetric alarm system that can detect any movement in the intrusion area, based on monitoring the change over time of the impulse response of the room, which acts as an acoustic footprint. The device depends on an omnidirectional ultrasonic transducer array emitting sweep signals to calculate the impulse response in short intervals. Any change in the room conditions is monitored through a correlation function. The sensitivity of the alarm to different objects and different environments depends on the sweep duration, sweep bandwidth, and sweep interval. Successful detection of intrusions also depends on the size of the monitoring area and requires an adjustment of emitted ultrasound power. Strong air flow affects the performance of the alarm. A method for separating moving objects from strong air flow is devised using an adaptive thresholding on the correlation function involving a series of impulse response measurements. The alarm system can be also used for fire detection since air flow sourced from heating objects differ from random nature of the present air flow. Several measurements are made to test the integrity of the alarm in rooms sizing from 834-2080m3 with irregular geometries and various objects. The proposed system can efficiently detect intrusion whilst adequate emitting power is provided.

Fundamental considerations in ski binding analysis.

PubMed

Mote, C D; Hull, M L

1976-01-01

1. The static adjustment of a ski binding by hand or by available machines is only an adjustment and is neither a static nor a dynamic evaluation of the binding design. Bindings of different design with identical static adjustments will perform differently in environments in which the forces are static or dynamic. 2. The concept of binding release force is a useful measure of binding adjustment, but it is inappropriate as a criterion for binding evaluation. First, it does not direct attention toward the injury causing mechanism, strain, or displacement in the leg. Second, it is only part of the evaluation in dynamic problems. 3. The binding release decision in present bindings is displacement controlled. The relative displacement of the boot and ski is the system variable. For any specified relative displacement the binding force can be any of an infinite number of possibilities determined by the loading path. 4. The response of the leg-ski system to external impulses applied to the ski is independent of the boot-ski relative motion as long as the boot recenters quickly in the binding. Response is dependent upon the external impulse plus system inertia, damping and stiffness. 5. When tested under half sinusoidal forces applied to a test ski, all bindings will demonstrate static and impulse loading regions. In the static region the force drives the binding to a relative release displacement. In the impulse region the initial velocity of the ski drives the binding to a release displacement. 6. The transition between the static and impulse loading regions is determined by the binding's capacity to store and dissipate energy along the principal loading path. Increased energy capacity necessitates larger external impulses to produce release. 7. In all bindings examined to date, the transmitted leg displacement or strain at release under static loading exceeds leg strain under dynamic or impact loading. Because static loading is responsible for many injuries, a skier should be able to release his bindings in every mode by simply pulling or twisting his foot outward. If that cannot be done without injury, the skier has identified for himself one type of fall that will result in injury. 8. And lastly, a little advice from Ben Franklin--"Carelessness does more harm than a want of knowledge."

VAR and generalized impulse response analysis of manufacturing unit labor costs

NASA Astrophysics Data System (ADS)

Ewing, Bradley T.; Thompson, Mark A.

2008-04-01

This paper examines the relationship among manufacturing unit labor costs in the United States, United Kingdom, and Canada. The analysis is conducted within the context of an economic system utilizing the recently developed method of generalized impulse response analysis to simulate the responses of the cost series to disturbances. The results indicate that, while unit labor costs do not share a common stochastic trend, there are significant responses in the unit labor costs of each country to shocks in the costs of other countries that are not captured by standard interpretation of the multiple-equation model results. The findings indicate the presence of significant linkages among unit labor costs in the countries studied. The results are consistent with the economic environment of manufacturing operations being characterized by a competitive, integrated marketplace.

(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

Systolic Signal Processor/High Frequency Direction Finding

DTIC Science & Technology

1990-10-01

MUSIC ) algorithm and the finite impulse response (FIR) filter onto the testbed hardware was supported by joint sponsorship of the block and major bid...computational throughput. The systolic implementations of a four-channel finite impulse response (FIR) filter and multiple signal classification ( MUSIC ... MUSIC ) algorithm was mated to a bank of finite impulse response (FIR) filters and a four-channel data acquisition subsystem. A complete description

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.

Digestive System

MedlinePlus

... think about eating. In response to this sensory stimulation, the brain sends impulses through the nerves that ... it based on symptoms, medical history, and a physical exam. Problems With the Pancreas, Liver, and Gallbladder ...

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 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.

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.

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

Direction Finding Using an Antenna with Direction Dependent Impulse Response

NASA Technical Reports Server (NTRS)

Foltz, Heinrich; Kegege, Obadiah

2016-01-01

Wideband antennas may be designed to have an impulse response that is direction dependent, not only in amplitude but also in waveform shape. This property can be used to perform direction finding using a single fixed antenna, without the need for an array or antenna rotation. In this paper direction finding is demonstrated using a simple candelabra-shaped monopole operating in the 1-3 GHz range. The method requires a known transmitted pulse shape and high signal-to-noise ratio, and is not as accurate or robust as conventional methods. However, it can add direction finding capability to a wideband communication system without the addition of any hardware.

A fresh look at linear ordinary differential equations with constant coefficients. Revisiting the impulsive response method using factorization

NASA Astrophysics Data System (ADS)

Camporesi, Roberto

2016-01-01

We present an approach to the impulsive response method for solving linear constant-coefficient ordinary differential equations of any order based on the factorization of the differential operator. The approach is elementary, we only assume a basic knowledge of calculus and linear algebra. In particular, we avoid the use of distribution theory, as well as of the other more advanced approaches: Laplace transform, linear systems, the general theory of linear equations with variable coefficients and variation of parameters. The approach presented here can be used in a first course on differential equations for science and engineering majors.

Phase-Locked Optical Generation of mmW/THz Signals

DTIC Science & Technology

2009-11-01

22 6.2. TIA (Trans-Impedance Amplifier ...24 6.3. Variable gain Amplifier ...loop architectures. Generate models including detector impulse response, feedback amplifier impulse response and laser current tuning response

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.

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.

Methylphenidate and Atomoxetine-Responsive Prefrontal Cortical Genetic Overlaps in "Impulsive" SHR/NCrl and Wistar Rats.

PubMed

Dela Peña, Ike; Dela Peña, Irene Joy; de la Peña, June Bryan; Kim, Hee Jin; Shin, Chan Young; Han, Doug Hyun; Kim, Bung-Nyun; Ryu, Jong Hoon; Cheong, Jae Hoon

2017-09-01

Impulsivity, the predisposition to act prematurely without foresight, is associated with a number of neuropsychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD). Identifying genetic underpinnings of impulsive behavior may help decipher the complex etiology and neurobiological factors of disorders marked by impulsivity. To identify potential genetic factors of impulsivity, we examined common differentially expressed genes (DEGs) in the prefrontal cortex (PFC) of adolescent SHR/NCrl and Wistar rats, which showed marked decrease in preference for the large but delayed reward, compared with WKY/NCrl rats, in the delay discounting task. Of these DEGs, we examined drug-responsive transcripts whose mRNA levels were altered following treatment (in SHR/NCrl and Wistar rats) with drugs that alleviate impulsivity, namely, the ADHD medications methylphenidate and atomoxetine. Prefrontal cortical genetic overlaps between SHR/NCrl and Wistar rats in comparison with WKY/NCrl included genes associated with transcription (e.g., Btg2, Fos, Nr4a2), synaptic plasticity (e.g., Arc, Homer2), and neuron apoptosis (Grik2, Nmnat1). Treatment with methylphenidate and/or atomoxetine increased choice of the large, delayed reward in SHR/NCrl and Wistar rats and changed, in varying degrees, mRNA levels of Nr4a2, Btg2, and Homer2, genes with previously described roles in neuropsychiatric disorders characterized by impulsivity. While further studies are required, we dissected potential genetic factors that may influence impulsivity by identifying genetic overlaps in the PFC of "impulsive" SHR/NCrl and Wistar rats. Notably, these are also drug-responsive transcripts which may be studied further as biomarkers to predict response to ADHD drugs, and as potential targets for the development of treatments to improve impulsivity.

A theoretical and experimental investigation of the linear and nonlinear impulse responses from a magnetoplasma column

NASA Technical Reports Server (NTRS)

Grody, N. C.

1973-01-01

Linear and nonlinear responses of a magnetoplasma resulting from inhomogeneity in the background plasma density are studied. The plasma response to an impulse electric field was measured and the results are compared with the theory of an inhomogeneous cold plasma. Impulse responses were recorded for the different plasma densities, static magnetic fields, and neutral pressures and generally appeared as modulated, damped oscillations. The frequency spectra of the waveforms consisted of two separated resonance peaks. For weak excitation, the results correlate with the linear theory of a cold, inhomogeneous, cylindrical magnetoplasma. The damping mechanism is identified with that of phase mixing due to inhomogeneity in plasma density. With increasing excitation voltage, the nonlinear impulse responses display stronger damping and a small increase in the frequency of oscillation.

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.

Neurogenetics and Epigenetics in Impulsive Behaviour: Impact on Reward Circuitry

PubMed Central

Archer, Trevor; Oscar-Berman, Marlene; Blum, Kenneth; Gold, Mark

2012-01-01

Adverse, unfavourable life conditions, particularly during early life stages and infancy, can lead to epigenetic regulation of genes involved in stress-response, behavioral disinhibition, and cognitive-emotional systems. Over time, the ultimate final outcome can be expressed through behaviors bedeviled by problems with impulse control, such as eating disorders, alcoholism, and indiscriminate social behavior. While many reward gene polymorphisms are involved in impulsive behaviors, a polymorphism by itself may not translate to the development of a particular behavioral disorder unless it is impacted by epigenetic effects. Brain-derived neurotrophic factor (BDNF) affects the development and integrity of the noradrenergic, dopaminergic, serotonergic, glutamatergic, and cholinergic neurotransmitter systems, and plasma levels of the neurotrophin are associated with both cognitive and aggressive impulsiveness. Epigenetic mechanisms associated with a multitude of environmental factors, including premature birth, low birth weight, prenatal tobacco exposure, non-intact family, young maternal age at birth of the target child, paternal history of antisocial behavior, and maternal depression, alter the developmental trajectories for several neuropsychiatric disorders. These mechanisms affect brain development and integrity at several levels that determine structure and function in resolving the final behavioral expressions. PMID:23264884

Evidence for impulsivity in the Spontaneously Hypertensive Rat drawn from complementary response-withholding tasks

PubMed Central

Sanabria, Federico; Killeen, Peter R

2008-01-01

Background The inability to inhibit reinforced responses is a defining feature of ADHD associated with impulsivity. The Spontaneously Hypertensive Rat (SHR) has been extolled as an animal model of ADHD, but there is no clear experimental evidence of inhibition deficits in SHR. Attempts to demonstrate these deficits may have suffered from methodological and analytical limitations. Methods We provide a rationale for using two complementary response-withholding tasks to doubly dissociate impulsivity from motivational and motor processes. In the lever-holding task (LHT), continual lever depression was required for a minimum interval. Under a differential reinforcement of low rates schedule (DRL), a minimum interval was required between lever presses. Both tasks were studied using SHR and two normotensive control strains, Wistar-Kyoto (WKY) and Long Evans (LE), over an overlapping range of intervals (1 – 5 s for LHT and 5 – 60 s for DRL). Lever-holding and DRL performance was characterized as the output of a mixture of two processes, timing and iterative random responding; we call this account of response inhibition the Temporal Regulation (TR) model. In the context of TR, impulsivity was defined as a bias toward premature termination of the timed intervals. Results The TR model provided an accurate description of LHT and DRL performance. On the basis of TR parameter estimates, SHRs were more impulsive than LE rats across tasks and target times. WKY rats produced substantially shorter timed responses in the lever-holding task than in DRL, suggesting a motivational or motor deficit. The precision of timing by SHR, as measured by the variance of their timed intervals, was excellent, flouting expectations from ADHD research. Conclusion This research validates the TR model of response inhibition and supports SHR as an animal model of ADHD-related impulsivity. It indicates, however, that SHR's impulse-control deficit is not caused by imprecise timing. The use of ad hoc impulsivity metrics and of WKY as control strain for SHR impulsivity are called into question. PMID:18261220

Identification of Computational and Experimental Reduced-Order Models

NASA Technical Reports Server (NTRS)

Silva, Walter A.; Hong, Moeljo S.; Bartels, Robert E.; Piatak, David J.; Scott, Robert C.

2003-01-01

The identification of computational and experimental reduced-order models (ROMs) for the analysis of unsteady aerodynamic responses and for efficient aeroelastic analyses is presented. For the identification of a computational aeroelastic ROM, the CFL3Dv6.0 computational fluid dynamics (CFD) code is used. Flutter results for the AGARD 445.6 Wing and for a Rigid Semispan Model (RSM) computed using CFL3Dv6.0 are presented, including discussion of associated computational costs. Modal impulse responses of the unsteady aerodynamic system are computed using the CFL3Dv6.0 code and transformed into state-space form. The unsteady aerodynamic state-space ROM is then combined with a state-space model of the structure to create an aeroelastic simulation using the MATLAB/SIMULINK environment. The MATLAB/SIMULINK ROM is then used to rapidly compute aeroelastic transients, including flutter. The ROM shows excellent agreement with the aeroelastic analyses computed using the CFL3Dv6.0 code directly. For the identification of experimental unsteady pressure ROMs, results are presented for two configurations: the RSM and a Benchmark Supercritical Wing (BSCW). Both models were used to acquire unsteady pressure data due to pitching oscillations on the Oscillating Turntable (OTT) system at the Transonic Dynamics Tunnel (TDT). A deconvolution scheme involving a step input in pitch and the resultant step response in pressure, for several pressure transducers, is used to identify the unsteady pressure impulse responses. The identified impulse responses are then used to predict the pressure responses due to pitching oscillations at several frequencies. Comparisons with the experimental data are then presented.

Effects of channel tap spacing on delay-lock tracking

NASA Astrophysics Data System (ADS)

Dana, Roger A.; Milner, Brian R.; Bogusch, Robert L.

1995-12-01

High fidelity simulations of communication links operating through frequency selective fading channels require both accurate channel models and faithful reproduction of the received signal. In modern radio receivers, processing beyond the analog-to-digital converter (A/D) is done digitally, so a high fidelity simulation is actually an emulation of this digital signal processing. The 'simulation' occurs in constructing the output of the A/D. One approach to constructing the A/D output is to convolve the channel impulse response function with the combined impulse response of the transmitted modulation and the A/D. For both link simulations and hardware channel simulators, the channel impulse response function is then generated with a finite number of samples per chip, and the convolution is implemented in a tapped delay line. In this paper we discuss the effects of the channel model tap spacing on the performance of delay locked loops (DLLs) in both direct sequence and frequency hopped spread spectrum systems. A frequency selective fading channel is considered, and the channel impulse response function is constructed with an integer number of taps per modulation symbol or chip. The tracking loop time delay is computed theoretically for this tapped delay line channel model and is compared to the results of high fidelity simulations of actual DLLs. A surprising result is obtained. The performance of the DLL depends strongly on the number of taps per chip. As this number increases the DLL delay approaches the theoretical limit.

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

Time-Reversal Based Range Extension Technique for Ultra-wideband (UWB) Sensors and Applications in Tactical Communications and Networking

DTIC Science & Technology

2009-04-16

the transmitted waveform, then spectral mask, notch line of Arbitrary Notch Filter , the designed waveforms and multipath impulse response represented...400 Frequence (MHz) Figure 5.4: Spectral mask, notch line of Arbitrary Notch Filter , the designed waveforms and multipath impulse response...600 Frequence (MHz) Figure 5.7: Spectral mask, notch line of Arbitrary Notch Filter , the designed waveforms and multipath impulse response

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.

Digital Image Deblurring by Nonlinear Homomorphic Filtering

DTIC Science & Technology

1974-08-01

Noise Film Grain Noise Impulse Noise Nois» and the ReVlection Scanner Page iv vii viii 1 1 2 4 5 7 8 11 11 12 IB 20 25...1. "^ bCx.y), n(x,y) Diagram 1 a(x,y) le the impulse response, or point-spread function, of the system, and la assumed to be unknown. All noise ... deblurring problem. This inadequacy results from the fact that the high frequency noise floor in the pouer spectrum of a blurred imaga U about 60 dbt

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.

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.

Description and Validation of a Dynamical Systems Model of Presynaptic Serotonin Function: Genetic Variation, Brain Activation and Impulsivity

PubMed Central

Stoltenberg, Scott F.; Nag, Parthasarathi

2010-01-01

Despite more than a decade of empirical work on the role of genetic polymorphisms in the serotonin system on behavior, the details across levels of analysis are not well understood. We describe a mathematical model of the genetic control of presynaptic serotonergic function that is based on control theory, implemented using systems of differential equations, and focused on better characterizing pathways from genes to behavior. We present the results of model validation tests that include the comparison of simulation outcomes with empirical data on genetic effects on brain response to affective stimuli and on impulsivity. Patterns of simulated neural firing were consistent with recent findings of additive effects of serotonin transporter and tryptophan hydroxylase-2 polymorphisms on brain activation. In addition, simulated levels of cerebral spinal fluid 5-hydroxyindoleacetic acid (CSF 5-HIAA) were negatively correlated with Barratt Impulsiveness Scale (Version 11) Total scores in college students (r = −.22, p = .002, N = 187), which is consistent with the well-established negative correlation between CSF 5-HIAA and impulsivity. The results of the validation tests suggest that the model captures important aspects of the genetic control of presynaptic serotonergic function and behavior via brain activation. The proposed model can be: (1) extended to include other system components, neurotransmitter systems, behaviors and environmental influences; (2) used to generate testable hypotheses. PMID:20111992

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.

Impulsivity and AMPA receptors: aniracetam ameliorates impulsive behavior induced by a blockade of AMPA receptors in rats.

PubMed

Nakamura, K; Kurasawa, M; Shirane, M

2000-04-17

The study aimed to ascertain the involvement of central AMPA receptors in impulsive behaviors of aged rats and to examine the effects of aniracetam. Premature response in the two-lever choice reaction task was assessed as an index of impulsivity. Intracerebroventricular injection of 2, 3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline (NBQX), an AMPA receptor antagonist, dose-dependently (10.1-1009 ng/rat) increased only premature response without altering responding speed and choice accuracy 30 min after the injection. Aniracetam (30 mg/kg p.o.), a positive allosteric modulator of AMPA receptors, or AMPA (55.9 ng/rat, co-injected with NBQX) completely restored the NBQX-induced increase in impulsivity. These results indicate that AMPA receptors are tonically involved in the regulation of impulsivity.

Oscillatory Activity in the Medial Prefrontal Cortex and Nucleus Accumbens Correlates with Impulsivity and Reward Outcome

PubMed Central

Rich, P. Dylan; Nevado-Holgado, Alejo J.; Fernando, Anushka B. P.; Van Dijck, Gert; Holzhammer, Tobias; Paul, Oliver; Ruther, Patrick; Paulsen, Ole; Robbins, Trevor W.; Dalley, Jeffrey W.

2014-01-01

Actions expressed prematurely without regard for their consequences are considered impulsive. Such behaviour is governed by a network of brain regions including the prefrontal cortex (PFC) and nucleus accumbens (NAcb) and is prevalent in disorders including attention deficit hyperactivity disorder (ADHD) and drug addiction. However, little is known of the relationship between neural activity in these regions and specific forms of impulsive behaviour. In the present study we investigated local field potential (LFP) oscillations in distinct sub-regions of the PFC and NAcb on a 5-choice serial reaction time task (5-CSRTT), which measures sustained, spatially-divided visual attention and action restraint. The main findings show that power in gamma frequency (50–60 Hz) LFP oscillations transiently increases in the PFC and NAcb during both the anticipation of a cue signalling the spatial location of a nose-poke response and again following correct responses. Gamma oscillations were coupled to low-frequency delta oscillations in both regions; this coupling strengthened specifically when an error response was made. Theta (7–9 Hz) LFP power in the PFC and NAcb increased during the waiting period and was also related to response outcome. Additionally, both gamma and theta power were significantly affected by upcoming premature responses as rats waited for the visual cue to respond. In a subgroup of rats showing persistently high levels of impulsivity we found that impulsivity was associated with increased error signals following a nose-poke response, as well as reduced signals of previous trial outcome during the waiting period. Collectively, these in-vivo neurophysiological findings further implicate the PFC and NAcb in anticipatory impulsive responses and provide evidence that abnormalities in the encoding of rewarding outcomes may underlie trait-like impulsive behaviour. PMID:25333512

Clarifying Relations Between Dispositional Aggression and Brain Potential Response: Overlapping and Distinct Contributions of Impulsivity and Stress Reactivity

PubMed Central

Venables, Noah C.; Patrick, Christopher J.; Hall, Jason R.; Bernat, Edward M.

2011-01-01

Impulsive-aggressive individuals exhibit deficits in amplitude of the P3 brain potential response, however, it remains unclear how separable dispositional traits account for this association. The current study sought to clarify the basis of this association by examining contributions of trait impulsiveness and stress reactivity to the observed relationship between dispositional aggression and amplitude of the P3 brain potential response in a visual novelty-oddball procedure. A significant negative association was found between aggressiveness and amplitude of P3 response to both target and novel stimuli over frontal-central scalp sites. Impulsivity showed a parallel inverse relationship with P3 amplitude, attributable to its overlap with dispositional aggression. In contrast, stress reactivity did not exhibit a zero-order association with P3 amplitude, but modestly predicted P3 in a positive direction after accounting for its overlap with aggression. Results are discussed in terms of their implications for individual difference variables and brain processes underlying impulsive-aggressive behavior. PMID:21262318

Post-error action control is neurobehaviorally modulated under conditions of constant speeded response.

PubMed

Soshi, Takahiro; Ando, Kumiko; Noda, Takamasa; Nakazawa, Kanako; Tsumura, Hideki; Okada, Takayuki

2014-01-01

Post-error slowing (PES) is an error recovery strategy that contributes to action control, and occurs after errors in order to prevent future behavioral flaws. Error recovery often malfunctions in clinical populations, but the relationship between behavioral traits and recovery from error is unclear in healthy populations. The present study investigated the relationship between impulsivity and error recovery by simulating a speeded response situation using a Go/No-go paradigm that forced the participants to constantly make accelerated responses prior to stimuli disappearance (stimulus duration: 250 ms). Neural correlates of post-error processing were examined using event-related potentials (ERPs). Impulsivity traits were measured with self-report questionnaires (BIS-11, BIS/BAS). Behavioral results demonstrated that the commission error for No-go trials was 15%, but PES did not take place immediately. Delayed PES was negatively correlated with error rates and impulsivity traits, showing that response slowing was associated with reduced error rates and changed with impulsivity. Response-locked error ERPs were clearly observed for the error trials. Contrary to previous studies, error ERPs were not significantly related to PES. Stimulus-locked N2 was negatively correlated with PES and positively correlated with impulsivity traits at the second post-error Go trial: larger N2 activity was associated with greater PES and less impulsivity. In summary, under constant speeded conditions, error monitoring was dissociated from post-error action control, and PES did not occur quickly. Furthermore, PES and its neural correlate (N2) were modulated by impulsivity traits. These findings suggest that there may be clinical and practical efficacy of maintaining cognitive control of actions during error recovery under common daily environments that frequently evoke impulsive behaviors.

Post-error action control is neurobehaviorally modulated under conditions of constant speeded response

PubMed Central

Soshi, Takahiro; Ando, Kumiko; Noda, Takamasa; Nakazawa, Kanako; Tsumura, Hideki; Okada, Takayuki

2015-01-01

Post-error slowing (PES) is an error recovery strategy that contributes to action control, and occurs after errors in order to prevent future behavioral flaws. Error recovery often malfunctions in clinical populations, but the relationship between behavioral traits and recovery from error is unclear in healthy populations. The present study investigated the relationship between impulsivity and error recovery by simulating a speeded response situation using a Go/No-go paradigm that forced the participants to constantly make accelerated responses prior to stimuli disappearance (stimulus duration: 250 ms). Neural correlates of post-error processing were examined using event-related potentials (ERPs). Impulsivity traits were measured with self-report questionnaires (BIS-11, BIS/BAS). Behavioral results demonstrated that the commission error for No-go trials was 15%, but PES did not take place immediately. Delayed PES was negatively correlated with error rates and impulsivity traits, showing that response slowing was associated with reduced error rates and changed with impulsivity. Response-locked error ERPs were clearly observed for the error trials. Contrary to previous studies, error ERPs were not significantly related to PES. Stimulus-locked N2 was negatively correlated with PES and positively correlated with impulsivity traits at the second post-error Go trial: larger N2 activity was associated with greater PES and less impulsivity. In summary, under constant speeded conditions, error monitoring was dissociated from post-error action control, and PES did not occur quickly. Furthermore, PES and its neural correlate (N2) were modulated by impulsivity traits. These findings suggest that there may be clinical and practical efficacy of maintaining cognitive control of actions during error recovery under common daily environments that frequently evoke impulsive behaviors. PMID:25674058

Response Inhibition Impairments Predict Alcohol-Induced Sedation

PubMed Central

Shannon, Erin E.; Staniforth, Elizabeth R.; McNamara, Juliette; Bernosky-Smith, Kimberly A.; Liguori, Anthony

2011-01-01

Aims: The aim of this study was to probe the relationship between the subjective effects of alcohol and impulsive behavior in social drinkers. Methods: Fifty social drinkers performed a response-inhibition task before consuming alcohol. A 0.8-g/kg dose of alcohol was administered in a binge-like fashion (0.2 g/kg every 30 min) to the participants over a 2-h time period. Participants then completed questionnaires measuring stimulation, sedation and mood following consumption of alcohol. Linear regression analyses were performed by examining the relationship between performance on the response inhibition impulsivity task and subjective responses to alcohol (i.e. stimulation, sedation and arousal). Results: There was a significant positive relationship found between impulsive responding and self-reported sedation following alcohol consumption. Additionally, there was a significant negative relationship between behavioral impulsivity and self-reported stimulation and arousal following alcohol consumption. Conclusion: These results suggest that higher levels of impulsivity are associated with experiencing greater sedating than stimulating effects of alcohol. Individuals with high levels of impulsivity may be less sensitive to the stimulating effects of a specified dose of alcohol, which could lead to these individuals consuming more alcohol to experience the stimulating effects of alcohol. PMID:21127353

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.

Dynamic Behaviour and Seismic Response of Ground Supported Cylindrical Water Tanks

NASA Astrophysics Data System (ADS)

Asha, Joseph; Glory, Joseph

2018-05-01

Liquid storage tank such as in water distribution systems, petroleum plants etc., constitute a vital component of life line systems. Reducing earthquake effects on liquid storage tanks, to minimize the environmental and economic impact of these effects, have always been an important engineering concern. In this paper, the dynamic behavior of cylindrical ground supported concrete water tanks with different aspect ratios is investigated using finite element software ANSYS. The natural frequencies and modal responses are obtained for impulsive and convective modes of vibration. The natural frequency of vibration of the tank is observed to be the lowest at maximum water depth. The fundamental impulsive frequency increases as water level reduces and for water level less than 1/3 of tank height, there is significantly no change in impulsive frequency. The effect of wall flexibility on dynamic behavior of the tank is investigated by performing the modal analysis of flexible and rigid tanks. For a partially filled tank, the results of the present study are of significant relevance. The response of the tank to the transient loading as horizontal ground motion of El Centro earthquake is studied for various water heights. As the height of water on the tank increases, the ultimate maximum seismic response parameters are also observed to be increased. The location of maximum hoop stress varies in accordance with the variations in input ground motion and water fill condition whereas shear and bending moment are maximum at the base.

From reactive to proactive and selective control: developing a richer model for stopping inappropriate responses

PubMed Central

Aron, Adam R

2010-01-01

A better understanding of the neural systems underlying impulse control is important for psychiatry. While most impulses are motivational or emotional rather than motoric per se, it is research into the neural architecture of motor response control that has made the greatest strides. This article reviews recent developments in the cognitive neuroscience of stopping responses. Most research of this kind has focused on reactive control – i.e. how subjects stop a response outright when instructed by a signal. It is argued that reactive paradigms are limited as models of control relevant to psychiatry. Instead, a set of paradigms is advocated that begins to model proactive inhibitory control – i.e. how a subject prepares to stop an upcoming response tendency. Proactive inhibitory control is generated according to the goals of the subject, rather than by an external signal, and it can be selectively targeted at a particular response tendency. This may have wider validity than reactive control as an experimental model for stopping inappropriate responses. PMID:20932513

Dynamic response and transfer function of social systems: A neuro-inspired model of collective human activity patterns.

PubMed

Lymperopoulos, Ilias N

2017-10-01

The interaction of social networks with the external environment gives rise to non-stationary activity patterns reflecting the temporal structure and strength of exogenous influences that drive social dynamical processes far from an equilibrium state. Following a neuro-inspired approach, based on the dynamics of a passive neuronal membrane, and the firing rate dynamics of single neurons and neuronal populations, we build a state-of-the-art model of the collective social response to exogenous interventions. In this regard, we analyze online activity patterns with a view to determining the transfer function of social systems, that is, the dynamic relationship between external influences and the resulting activity. To this end, first we estimate the impulse response (Green's function) of collective activity, and then we show that the convolution of the impulse response with a time-varying external influence field accurately reproduces empirical activity patterns. To capture the dynamics of collective activity when the generating process is in a state of statistical equilibrium, we incorporate into the model a noisy input convolved with the impulse response function, thus precisely reproducing the fluctuations of stationary collective activity around a resting value. The outstanding goodness-of-fit of the model results to empirical observations, indicates that the model explains human activity patterns generated by time-dependent external influences in various socio-economic contexts. The proposed model can be used for inferring the temporal structure and strength of external influences, as well as the inertia of collective social activity. Furthermore, it can potentially predict social activity patterns. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

Hydrograph separation for karst watersheds using a two-domain rainfall-discharge model

USGS Publications Warehouse

Long, Andrew J.

2009-01-01

Highly parameterized, physically based models may be no more effective at simulating the relations between rainfall and outflow from karst watersheds than are simpler models. Here an antecedent rainfall and convolution model was used to separate a karst watershed hydrograph into two outflow components: one originating from focused recharge in conduits and one originating from slow flow in a porous annex system. In convolution, parameters of a complex system are lumped together in the impulse-response function (IRF), which describes the response of the system to an impulse of effective precipitation. Two parametric functions in superposition approximate the two-domain IRF. The outflow hydrograph can be separated into flow components by forward modeling with isolated IRF components, which provides an objective criterion for separation. As an example, the model was applied to a karst watershed in the Madison aquifer, South Dakota, USA. Simulation results indicate that this watershed is characterized by a flashy response to storms, with a peak response time of 1 day, but that 89% of the flow results from the slow-flow domain, with a peak response time of more than 1 year. This long response time may be the result of perched areas that store water above the main water table. Simulation results indicated that some aspects of the system are stationary but that nonlinearities also exist.

Intruder detection system

NASA Technical Reports Server (NTRS)

Lee, R. D. (Inventor)

1973-01-01

An intruder detection system is described. The system contains a transmitter which sends a frequency modulated and amplitude modulated signal to a remote receiver in response to a geophone detector which responds to seismic impulses created by the intruder. The signal makes it possible for an operator to determine the number of intruders and the manner of movement.

Overweight in adolescent, psychiatric inpatients: A problem of general or food-specific impulsivity?

PubMed

Deux, Natalie; Schlarb, Angelika A; Martin, Franziska; Holtmann, Martin; Hebebrand, Johannes; Legenbauer, Tanja

2017-05-01

Adolescent psychiatric patients are vulnerable to weight problems and show an overrepresentation of overweight compared to the healthy population. One potential factor that can contribute to the etiology of overweight is higher impulsivity. As of yet, it is unclear whether it is a general impulse control deficit or weight-related aspects such as lower impulse control in response to food that have an impact on body weight. As this may have therapeutic implications, the current study investigated differences between overweight and non-overweight adolescent psychiatric inpatients (N = 98; aged 12-20) in relation to trait impulsivity and behavioral inhibition performance. The Barratt Impulsiveness Scale and two go/no-go paradigms with neutral and food-related stimulus materials were applied. Results indicated no significant differences concerning trait impulsivity, but revealed that overweight inpatients had significantly more difficulties in inhibition performance (i.e. they reacted more impulsively) in response to both food and neutral stimuli compared to non-overweight inpatients. Furthermore, no specific inhibition deficit for high-caloric vs. low-caloric food cues emerged in overweight inpatients, whereas non-overweight participants showed significantly lower inhibition skills in response to high-caloric than low-caloric food stimuli. The results highlight a rather general, non-food-specific reduced inhibition performance in an overweight adolescent psychiatric population. Further research is necessary to enhance the understanding of the role of impulsivity in terms of body weight status in this high-risk group of adolescent inpatients. Copyright © 2017 Elsevier Ltd. All rights reserved.

Weighted finite impulse response filter for chromatic dispersion equalization in coherent optical fiber communication systems

NASA Astrophysics Data System (ADS)

Zeng, Ziyi; Yang, Aiying; Guo, Peng; Feng, Lihui

2018-01-01

Time-domain CD equalization using finite impulse response (FIR) filter is now a common approach for coherent optical fiber communication systems. The complex weights of FIR taps are calculated from a truncated impulse response of the CD transfer function, and the modulus of the complex weights is constant. In our work, we take the limited bandwidth of a single channel signal into account and propose weighted FIRs to improve the performance of CD equalization. The key in weighted FIR filters is the selection and optimization of weighted functions. In order to present the performance of different types of weighted FIR filters, a square-root raised cosine FIR (SRRC-FIR) and a Gaussian FIR (GS-FIR) are investigated. The optimization of square-root raised cosine FIR and Gaussian FIR are made in term of the bit rate error (BER) of QPSK and 16QAM coherent detection signal. The results demonstrate that the optimized parameters of the weighted filters are independent of the modulation format, symbol rate and the length of transmission fiber. With the optimized weighted FIRs, the BER of CD equalization signal is decreased significantly. Although this paper has investigated two types of weighted FIR filters, i.e. SRRC-FIR filter and GS-FIR filter, the principle of weighted FIR can also be extended to other symmetric functions super Gaussian function, hyperbolic secant function and etc.

The Video Head Impulse Test (vHIT) of Semicircular Canal Function - Age-Dependent Normative Values of VOR Gain in Healthy Subjects.

PubMed

McGarvie, Leigh A; MacDougall, Hamish G; Halmagyi, G Michael; Burgess, Ann M; Weber, Konrad P; Curthoys, Ian S

2015-01-01

The video Head Impulse Test (vHIT) is now widely used to test the function of each of the six semicircular canals individually by measuring the eye rotation response to an abrupt head rotation in the plane of the canal. The main measure of canal adequacy is the ratio of the eye movement response to the head movement stimulus, i.e., the gain of the vestibulo-ocular reflex (VOR). However, there is a need for normative data about how VOR gain is affected by age and also by head velocity, to allow the response of any particular patient to be compared to the responses of healthy subjects in their age range. In this study, we determined for all six semicircular canals, normative values of VOR gain, for each canal across a range of head velocities, for healthy subjects in each decade of life. The VOR gain was measured for all canals across a range of head velocities for at least 10 healthy subjects in decade age bands: 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, 80-89. The compensatory eye movement response to a small, unpredictable, abrupt head rotation (head impulse) was measured by the ICS impulse prototype system. The same operator delivered every impulse to every subject. Vestibulo-ocular reflex gain decreased at high head velocities, but was largely unaffected by age into the 80- to 89-year age group. There were some small but systematic differences between the two directions of head rotation, which appear to be largely due to the fact that in this study only the right eye was measured. The results are considered in relation to recent evidence about the effect of age on VOR performance. These normative values allow the results of any particular patient to be compared to the values of healthy people in their age range and so allow, for example, detection of whether a patient has a bilateral vestibular loss. VOR gain, as measured directly by the eye movement response to head rotation, seems largely unaffected by aging.

Subthalamic nucleus stimulation influences expression and suppression of impulsive behaviour in Parkinson’s disease

PubMed Central

Ridderinkhof, K. Richard; Elias, William J.; Frysinger, Robert C.; Bashore, Theodore R.; Downs, Kara E.; van Wouwe, Nelleke C.; van den Wildenberg, Wery P. M.

2010-01-01

Past studies show beneficial as well as detrimental effects of subthalamic nucleus deep-brain stimulation on impulsive behaviour. We address this paradox by investigating individuals with Parkinson’s disease treated with subthalamic nucleus stimulation (n = 17) and healthy controls without Parkinson’s disease (n = 17) on performance in a Simon task. In this reaction time task, conflict between premature response impulses and goal-directed action selection is manipulated. We applied distributional analytic methods to separate the strength of the initial response impulse from the proficiency of inhibitory control engaged subsequently to suppress the impulse. Patients with Parkinson’s disease were tested when stimulation was either turned on or off. Mean conflict interference effects did not differ between controls and patients, or within patients when stimulation was on versus off. In contrast, distributional analyses revealed two dissociable effects of subthalamic nucleus stimulation. Fast response errors indicated that stimulation increased impulsive, premature responding in high conflict situations. Later in the reaction process, however, stimulation improved the proficiency with which inhibitory control was engaged to suppress these impulses selectively, thereby facilitating selection of the correct action. This temporal dissociation supports a conceptual framework for resolving past paradoxical findings and further highlights that dynamic aspects of impulse and inhibitory control underlying goal-directed behaviour rely in part on neural circuitry inclusive of the subthalamic nucleus. PMID:20861152

Response inhibition and impulsive decision-making in sexual offenders against children.

PubMed

Turner, Daniel; Laier, Christian; Brand, Matthias; Bockshammer, Tamara; Welsch, Robin; Rettenberger, Martin

2018-05-31

Current theories view impulsivity as an important factor in the explanation of sexual offending. While impulsivity itself is a multidimensional construct, response inhibition and impulsive decision-making are frequently discussed subcomponents. Impulsivity in sexual offenders could be triggered by sexual cues with high emotional significance. The present study compared response inhibition abilities and the degree of impulsive decision-making between 63 child sexual abusers and 63 nonoffending controls. A Go/No-Go task was used to assess response inhibition, while the Iowa Gambling Task (IGT) and the Game of Dice Task (GDT) were used for the assessment of decision-making. In contrast to previous studies, modified versions of the Go/No-Go task and the IGT were used, including pictures of the Not Real People-Set depicting nude adults and children. Child sexual abusers showed more deficits in response inhibition in the Go/No-Go task. Furthermore, decision-making was especially impaired by the presence of child images in child sexual abusers with more intense pedophilic sexual interests. In contrast, in the nonoffending controls the presence of preferred sexual cues (pictures of women) improved decision-making performance. No differences in overall GDT performance were found between the groups; however, child sexual abusers chose the riskiest option more frequently than nonoffending controls. In line with theoretical assumptions about the processes underlying sexual offending, child sexual abusers show more deficits in neuropsychological functioning, which may be related to more impulsive behaviors. These impairments could be triggered by the presence of sexually relevant cues. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Suicidality in Bipolar Disorder: The Role of Emotion-Triggered Impulsivity

PubMed Central

Johnson, Sheri L.; Carver, Charles S.; Tharp, Jordan A.

2018-01-01

A growing body of research suggests that impulsive responses to emotion more robustly predict suicidality than do other forms of impulsivity. This issue has not yet been examined within bipolar disorder, however. Participants diagnosed with bipolar I disorder (n = 133) and control participants (n = 110) diagnosed with no mood or psychotic disorder completed self-report measures of emotion-triggered impulsivity (Negative and Positive Urgency Scales) and interviews concerning lifetime suicidality. Analyses examined the effects of emotion-triggered impulsivity alone and in combination with gender, age of onset, depression severity, comorbid anxiety, comorbid substance use, and medication. A history of suicide ideation and attempts, as well as self-harm, were significantly more common in the bipolar disorder group compared with the control group. Impulsive responses to positive emotions related to suicide ideation, attempts, and self-harm within the bipolar group. Findings extend research on the importance of emotion-triggered impulsivity to a broad range of key outcomes within bipolar disorder. The discussion focuses on limitations and potential clinical implications. PMID:27406282

Experimental Investigations on Two Potential Sound Diffuseness Measures in Enclosures

NASA Astrophysics Data System (ADS)

Bai, Xin

This study investigates two different approaches to measure sound field diffuseness in enclosures from monophonic room impulse responses. One approach quantifies sound field diffuseness in enclosures by calculating the kurtosis of the pressure samples of room impulse responses. Kurtosis is a statistical measure that is known to describe the peakedness or tailedness of the distribution of a set of data. High kurtosis indicates low diffuseness of the sound field of interest. The other one relies on multifractal detrended fluctuation analysis which is a way to evaluate the statistical self-affinity of a signal to measure diffuseness. To test these two approaches, room impulse responses are obtained under varied room-acoustic diffuseness configurations, achieved by using varied degrees of diffusely reflecting interior surfaces. This paper will analyze experimentally measured monophonic room impulse responses, and discuss results from these two approaches.

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

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.

PET Measures of Endogenous Opioid Neurotransmission Predict Impulsiveness Traits in Humans

PubMed Central

Love, Tiffany M.; Stohler, Christian S.; Zubieta, Jon-Kar

2011-01-01

Objective The endogenous opioid system and μ-opioid receptors are known to interface environmental events, both positive (e.g., relevant emotional stimuli) and negative (e.g., stressors) with pertinent behavioral responses, regulating motivated behavior. Here we examined the degree to which trait impulsiveness, the tendency to act on cravings and urges rather than delaying gratification, is predicted by either baseline μ-opioid receptor availability or the response of this system to a standardized, experientially-matched stressor. Method Nineteen (19) young healthy male volunteers completed a personality questionnaire (NEO PI-R) and positron emission tomography scans with the μ-opioid receptor selective radiotracer [11C]carfentanil. Measures of receptor concentrations were obtained at rest and during the receipt of an experimentally maintained pain stressor of matched intensity between subjects. Baseline receptor levels and stress-induced activation of μ-opioid neurotransmission were compared between subjects scoring above and below the population median of the NEO impulsiveness subscale and the orthogonal dimension, deliberation, expected to interact with it. Results High impulsiveness and low deliberation scores were associated with significantly higher regional μ-opioid receptor concentrations and greater stress-induced endogenous opioid system activation. Effects were obtained in regions involved in motivated behavior and the effects of drugs of abuse: prefrontal and orbitofrontal cortex, anterior cingulate, thalamus, nucleus accumbens and basolateral amygdala. Mu-opioid receptor availability, and the magnitude of stress-induced endogenous opioid activation in these regions accounted for 21 to 49% of the variance in these personality traits. Conclusions Our data demonstrate that individual differences in the function of the endogenous μ-opioid system predicts personality traits that confer vulnerability or resiliency for risky behaviors, such as the predisposition to develop substance use disorders. These personality traits are also implicated in psychopathological states (e.g., personality disorders), where variations in the function of this neurotransmitter system may play a role as well. PMID:19805703

Effects of amphetamine exposure in adolescence or young adulthood on inhibitory control in adult male and female rats

PubMed Central

Hammerslag, Lindsey R.; Waldman, Alex J.; Gulley, Joshua M.

2014-01-01

Heightened impulsivity is a feature of some psychiatric disorders, including addiction, that also have sex-specific patterns of expression. The relationship between addiction and impulsivity may be driven by drug-induced changes in behavior caused by long term adaptations in signaling within the medial prefrontal cortex (mPFC). Here, we used a response inhibition task that is sensitive to changes in mPFC function to examine the effects of sex and exposure to amphetamine (AMPH) on impulsive action and vigilance. We also examined drug-induced alterations in glutamatergic and dopaminergic signaling through challenge injections with the NMDA receptor antagonist MK-801 (dizocilpine) and AMPH. Male and female Sprague Dawley rats were injected (i.p.) with saline or 3 mg/kg AMPH every other day during adolescence (postnatal day (P) 27–45) or adulthood (P85–103). Starting on P125–135, rats were tested for their ability to lever press for a food reward during periods of signaled availability and withhold responding during a “premature response” phase. In experiment 1, rats received challenge injections (i.p.) of MK-801 and AMPH followed by tests of task performance and locomotor activity. In experiment 2, rats received intra-mPFC infusion of MK-801. We found that females had better inhibitory control and poorer vigilance than males and that AMPH exposure had both sex- and age-of-exposure dependent effects on impulsivity. Systemic drug challenges disrupted task performance, particularly in females, and increased impulsivity while intra-mPFC infusions had modest effects. AMPH exposure did not affect responses to drug challenges. Together, these results suggest that sex mediates both trait and drug-induced impulsivity. PMID:24462963

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.

Overlapping and disease specific trait, response, and reflection impulsivity in adolescents with first-episode schizophrenia spectrum disorders or attention-deficit/hyperactivity disorder.

PubMed

Jepsen, J R M; Rydkjaer, J; Fagerlund, B; Pagsberg, A K; Jespersen, R Av F; Glenthøj, B Y; Oranje, B

2018-03-01

Schizophrenia and attention-deficit/hyperactivity disorder (ADHD) are developmental disorders with shared clinical characteristics such as cognitive impairments and impulsivity. Impulsivity is a core feature of ADHD and an important factor in aggression, violence, and substance use in schizophrenia. Based on the hypothesis that schizophrenia and ADHD represent a continuum of neurodevelopmental impairments, the aim was to identify overlapping and disease specific forms of impulsivity. Adolescents between 12 and 17 years of age were assessed with the Schedule for Affective Disorders and Schizophrenia for School-aged Children - Present and Lifetime Version. Subjects with early-onset, first-episode schizophrenia spectrum disorders (EOS) (N = 29) or ADHD (N = 29) and healthy controls (N = 45) were compared on two performance measures (Information Sampling Task, Stop Signal Task) and a subjective personality trait measure of impulsivity (Barratt Impulsiveness Scale, Version 11 (BIS-11)). Significantly increased reflection impulsivity was observed in ADHD but not in the EOS group. No significant response inhibition deficits (stop signal reaction time) were found in the two clinical groups. The ADHD and the EOS group showed significantly increased motor, attentional, and non-planning subtraits of impulsivity. Impaired pre-decisional information gathering appeared to be specific for ADHD while the information gathering was not significantly reduced in subjects with EOS. Neither the ADHD nor EOS group showed impaired response inhibition but shared increased personality subtraits of attentional, non-planning, and motor impulsivity although the latter was significantly more pronounced in ADHD. These increased subtraits of impulsivity may reflect diagnostic non-specific neurodevelopmental impairments in ADHD and EOS in adolescence.

The video head impulse test during post-rotatory nystagmus: physiology and clinical implications.

PubMed

Mantokoudis, Georgios; Tehrani, Ali S Saber; Xie, Li; Eibenberger, Karin; Eibenberger, Bernhard; Roberts, Dale; Newman-Toker, David E; Zee, David S

2016-01-01

The aim of this study was to test the effects of a sustained nystagmus on the head impulse response of the vestibulo-ocular reflex (VOR) in healthy subjects. VOR gain (slow-phase eye velocity/head velocity) was measured using video head impulse test goggles. Acting as a surrogate for a spontaneous nystagmus (SN), a post-rotatory nystagmus (PRN) was elicited after a sustained, constant-velocity rotation, and then head impulses were applied. 'Raw' VOR gain, uncorrected for PRN, in healthy subjects in response to head impulses with peak velocities in the range of 150°/s-250°/s was significantly increased (as reflected in an increase in the slope of the gain versus head velocity relationship) after inducing PRN with slow phases of nystagmus of high intensity (>30°/s) in the same but not in the opposite direction as the slow-phase response induced by the head impulses. The values of VOR gain themselves, however, remained in the normal range with slow-phase velocities of PRN < 30°/s. Finally, quick phases of PRN were suppressed during the first 20-160 ms of a head impulse; the time frame of suppression depended on the direction of PRN but not on the duration of the head impulse. Our results in normal subjects suggest that VOR gains measured using head impulses may have to be corrected for any superimposed SN when the slow-phase velocity of nystagmus is relatively high and the peak velocity of the head movements is relatively low. The suppression of quick phases during head impulses may help to improve steady fixation during rapid head movements.

Motor Impulsivity in Parkinson Disease: Associations with COMT and DRD2 polymorphisms

PubMed Central

Ziegler, David A.; Ashourian, Paymon; Wonderlick, Julien S.; Sarokhan, Alison K.; Prelec, Drazen; Scherzer, Clemens R.; Corkin, Suzanne

2017-01-01

Parkinson disease (PD) is an age-related degenerative disease of the brain, characterized by motor, cognitive, and psychiatric symptoms. Neurologists and neuroscientists now understand that several symptoms of the disease, including hallucinations and impulse control behaviors, stem from the dopaminergic medications used to control the motor aspects of PD. Converging evidence from animals and humans suggests that individual differences in the genes that affect the dopamine system influence the response of PD patients to dopaminergic medication. In this study, we tested the hypothesis that patients taking dopamine replacement therapy who carry candidate alleles that increase dopamine signaling exhibit greater amounts of motor impulsivity. We examined the relation between inhibitory ability (measured by the Stop Signal Task) and polymorphisms of COMT Val158Met and DRD2 C957T in patients with idiopathic PD. On the Stop Signal Task, carriers of COMT Val/Met and Met/Met genotypes were more impulsive than Val/Val carriers, but we did not find a link between DRD2 polymorphisms and inhibitory ability. These results support the hypothesis that the Met allele of COMT confers an increased risk for behavioral impulsivity in PD patients, whereas DRD2 polymorphisms appear to be less important in determining whether PD patients exhibit a dopamine overdose in the form of motor impulsivity. PMID:24749760

Clarifying relations between dispositional aggression and brain potential response: overlapping and distinct contributions of impulsivity and stress reactivity.

PubMed

Venables, Noah C; Patrick, Christopher J; Hall, Jason R; Bernat, Edward M

2011-03-01

Impulsive-aggressive individuals exhibit deficits in amplitude of the P3 brain potential response, however, it remains unclear how separable dispositional traits account for this association. The current study sought to clarify the basis of this association by examining contributions of trait impulsiveness and stress reactivity to the observed relationship between dispositional aggression and amplitude of the P3 brain potential response in a visual novelty-oddball procedure. A significant negative association was found between aggressiveness and amplitude of P3 response to both target and novel stimuli over frontal-central scalp sites. Impulsivity showed a parallel inverse relationship with P3 amplitude, attributable to its overlap with dispositional aggression. In contrast, stress reactivity did not exhibit a zero-order association with P3 amplitude, but modestly predicted P3 in a positive direction after accounting for its overlap with aggression. Results are discussed in terms of their implications for individual difference variables and brain processes underlying impulsive-aggressive behavior. Copyright © 2011 Elsevier B.V. All rights reserved.

Body weight status, eating behavior, sensitivity to reward/punishment, and gender: relationships and interdependencies

PubMed Central

Dietrich, Anja; Federbusch, Martin; Grellmann, Claudia; Villringer, Arno; Horstmann, Annette

2014-01-01

Behavioral and personality characteristics are factors that may jointly regulate body weight. This study explored the relationship between body mass index (BMI) and self-reported behavioral and personality measures. These measures included eating behavior (based on the Three-Factor Eating Questionnaire; Stunkard and Messick, 1985), sensitivity to reward and punishment (based on the Behavioral Inhibition System/Behavioral Activation System (BIS/BAS) scales) (Carver and White, 1994) and self-reported impulsivity (based on the Barratt Impulsiveness Scale-11; Patton et al., 1995). We found an inverted U-shaped relationship between restrained eating and BMI. This relationship was moderated by the level of disinhibited eating. Independent of eating behavior, BIS and BAS responsiveness were associated with BMI in a gender-specific manner with negative relationships for men and positive relationships for women. Together, eating behavior and BIS/BAS responsiveness accounted for a substantial proportion of BMI variance (men: ∼25%, women: ∼32%). A direct relationship between self-reported impulsivity and BMI was not observed. In summary, our results demonstrate a system of linear and non-linear relationships between the investigated factors and BMI. Moreover, body weight status was not only associated with eating behavior (cognitive restraint and disinhibition), but also with personality factors not inherently related to an eating context (BIS/BAS). Importantly, these relationships differ between men and women. PMID:25368586

Impulse position control algorithms for nonlinear systems

NASA Astrophysics Data System (ADS)

Sesekin, A. N.; Nepp, A. N.

2015-11-01

The article is devoted to the formalization and description of impulse-sliding regime in nonlinear dynamical systems that arise in the application of impulse position controls of a special kind. The concept of trajectory impulse-sliding regime formalized as some limiting network element Euler polygons generated by a discrete approximation of the impulse position control This paper differs from the previously published papers in that it uses a definition of solutions of systems with impulse controls, it based on the closure of the set of smooth solutions in the space of functions of bounded variation. The need for the study of such regimes is the fact that they often arise when parry disturbances acting on technical or economic control system.

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.

Non-stationary pre-envelope covariances of non-classically damped systems

NASA Astrophysics Data System (ADS)

Muscolino, G.

1991-08-01

A new formulation is given to evaluate the stationary and non-stationary response of linear non-classically damped systems subjected to multi-correlated non-separable Gaussian input processes. This formulation is based on a new and more suitable definition of the impulse response function matrix for such systems. It is shown that, when using this definition, the stochastic response of non-classically damped systems involves the evaluation of quantities similar to those of classically damped ones. Furthermore, considerations about non-stationary cross-covariances, spectral moments and pre-envelope cross-covariances are presented for a monocorrelated input process.

Post-capture vibration suppression of spacecraft via a bio-inspired isolation system

NASA Astrophysics Data System (ADS)

Dai, Honghua; Jing, Xingjian; Wang, Yu; Yue, Xiaokui; Yuan, Jianping

2018-05-01

Inspired by the smooth motions of a running kangaroo, a bio-inspired quadrilateral shape (BIQS) structure is proposed to suppress the vibrations of a free-floating spacecraft subject to periodic or impulsive forces, which may be encountered during on-orbit servicing missions. In particular, the BIQS structure is installed between the satellite platform and the capture mechanism. The dynamical model of the BIQS isolation system, i.e. a BIQS structure connecting the platform and the capture mechanism at each side, is established by Lagrange's equations to simulate the post-capture dynamical responses. The BIQS system suffering an impulsive force is dealt with by means of a modified version of Lagrange's equations. Furthermore, the classical harmonic balance method is used to solve the nonlinear dynamical system subject to periodic forces, while for the case under impulsive forces the numerical integration method is adopted. Due to the weightless environment in space, the present BIQS system is essentially an under-constrained dynamical system with one of its natural frequencies being identical to zero. The effects of system parameters, such as the number of layers in BIQS, stiffness, assembly angle, rod length, damping coefficient, masses of satellite platform and capture mechanism, on the isolation performance of the present system are thoroughly investigated. In addition, comparisons between the isolation performances of the presently proposed BIQS isolator and the conventional spring-mass-damper (SMD) isolator are conducted to demonstrate the advantages of the present isolator. Numerical simulations show that the BIQS system has a much better performance than the SMD system under either periodic or impulsive forces. Overall, the present BIQS isolator offers a highly efficient passive way for vibration suppressions of free-floating spacecraft.

The use of linear programming techniques to design optimal digital filters for pulse shaping and channel equalization

NASA Technical Reports Server (NTRS)

Houts, R. C.; Burlage, D. W.

1972-01-01

A time domain technique is developed to design finite-duration impulse response digital filters using linear programming. Two related applications of this technique in data transmission systems are considered. The first is the design of pulse shaping digital filters to generate or detect signaling waveforms transmitted over bandlimited channels that are assumed to have ideal low pass or bandpass characteristics. The second is the design of digital filters to be used as preset equalizers in cascade with channels that have known impulse response characteristics. Example designs are presented which illustrate that excellent waveforms can be generated with frequency-sampling filters and the ease with which digital transversal filters can be designed for preset equalization.

Behavioral Impulsivity Does Not Predict Naturalistic Alcohol Consumption or Treatment Outcomes

PubMed Central

Mullen, Jillian; Mathias, Charles W.; Karns, Tara E.; Liang, Yuanyuan; Hill-Kapturczak, Nathalie; Roache, John D.; Lamb, Richard J.; Dougherty, Donald M.

2016-01-01

Objective The purpose of this study was to determine if behavioral impulsivity under multiple conditions (baseline, after alcohol consumption or after serotonin depletion) predicted naturalistic alcohol use or treatment outcomes from a moderation-based contingency management intervention. Method The current data analysis pulls information from three phases of a large study: 1) Phase 1 examined baseline and the effects of alcohol use and serotonin depletion on three types of behavioral impulsivity: response initiation (IMT task), response inhibition (GoStop task), and delay discounting (SKIP task); 2) Phase 2 involved 28 days of naturalistic drinking; and 3) Phase 3 involved 3 months of contingency management. During phases 2 and 3 alcohol use was measured objectively using transdermal alcohol monitors. The results of each individual phase has been previously published showing that at a group level the effects of alcohol consumption on impulsivity were dependent on the component of impulsivity being measured and the dose of alcohol consumed but serotonin depletion had no effect on impulsivity, and that a moderation-based contingency management intervention reduced heavy drinking. Results The current analysis combining data from those who completed all three phases (n = 67) showed that impulsivity measured at baseline, after alcohol consumption, or after serotonin depletion did not predict naturalistic drinking or treatment outcomes from a moderation-based CM treatment. Conclusions Contingency management interventions may prove to be an effective intervention for impulsive individuals, however, normal variations in measured impulsivity do not seem to relate to normal variations in drinking pattern or response to moderation-based contingency management. PMID:27746702

Dominant modal decomposition method

NASA Astrophysics Data System (ADS)

Dombovari, Zoltan

2017-03-01

The paper deals with the automatic decomposition of experimental frequency response functions (FRF's) of mechanical structures. The decomposition of FRF's is based on the Green function representation of free vibratory systems. After the determination of the impulse dynamic subspace, the system matrix is formulated and the poles are calculated directly. By means of the corresponding eigenvectors, the contribution of each element of the impulse dynamic subspace is determined and the sufficient decomposition of the corresponding FRF is carried out. With the presented dominant modal decomposition (DMD) method, the mode shapes, the modal participation vectors and the modal scaling factors are identified using the decomposed FRF's. Analytical example is presented along with experimental case studies taken from machine tool industry.

Characterization of long-range functional connectivity in epileptic networks by neuronal spike-triggered local field potentials

NASA Astrophysics Data System (ADS)

Lopour, Beth A.; Staba, Richard J.; Stern, John M.; Fried, Itzhak; Ringach, Dario L.

2016-04-01

Objective. Quantifying the relationship between microelectrode-recorded multi-unit activity (MUA) and local field potentials (LFPs) in distinct brain regions can provide detailed information on the extent of functional connectivity in spatially widespread networks. These methods are common in studies of cognition using non-human animal models, but are rare in humans. Here we applied a neuronal spike-triggered impulse response to electrophysiological recordings from the human epileptic brain for the first time, and we evaluate functional connectivity in relation to brain areas supporting the generation of seizures. Approach. Broadband interictal electrophysiological data were recorded from microwires adapted to clinical depth electrodes that were implanted bilaterally using stereotactic techniques in six presurgical patients with medically refractory epilepsy. MUA and LFPs were isolated in each microwire, and we calculated the impulse response between the MUA on one microwire and the LFPs on a second microwire for all possible MUA/LFP pairs. Results were compared to clinical seizure localization, including sites of seizure onset and interictal epileptiform discharges. Main results. We detected significant interictal long-range functional connections in each subject, in some cases across hemispheres. Results were consistent between two independent datasets, and the timing and location of significant impulse responses reflected anatomical connectivity. However, within individual subjects, the spatial distribution of impulse responses was unique. In two subjects with clear seizure localization and successful surgery, the epileptogenic zone was associated with significant impulse responses. Significance. The results suggest that the spike-triggered impulse response can provide valuable information about the neuronal networks that contribute to seizures using only interictal data. This technique will enable testing of specific hypotheses regarding functional connectivity in epilepsy and the relationship between functional properties and imaging findings. Beyond epilepsy, we expect that the impulse response could be more broadly applied as a measure of long-range functional connectivity in studies of cognition.

Characterization of long-range functional connectivity in epileptic networks by neuronal spike-triggered local field potentials

PubMed Central

Lopour, Beth A; Staba, Richard J; Stern, John M; Fried, Itzhak; Ringach, Dario L

2017-01-01

Objective Quantifying the relationship between microelectrode-recorded multi-unit activity (MUA) and local field potentials (LFPs) in distinct brain regions can provide detailed information on the extent of functional connectivity in spatially widespread networks. These methods are common in studies of cognition using non-human animal models, but are rare in humans. Here we applied a neuronal spike-triggered impulse response to electrophysiological recordings from the human epileptic brain for the first time, and we evaluate functional connectivity in relation to brain areas supporting the generation of seizures. Approach Broadband interictal electrophysiological data were recorded from microwires adapted to clinical depth electrodes that were implanted bilaterally using stereotactic techniques in six presurgical patients with medically refractory epilepsy. MUA and LFPs were isolated in each microwire, and we calculated the impulse response between the MUA on one microwire and the LFPs on a second microwire for all possible MUA/LFP pairs. Results were compared to clinical seizure localization, including sites of seizure onset and interictal epileptiform discharges. Main results We detected significant interictal long-range functional connections in each subject, in some cases across hemispheres. Results were consistent between two independent datasets, and the timing and location of significant impulse responses reflected anatomical connectivity. However, within individual subjects, the spatial distribution of impulse responses was unique. In two subjects with clear seizure localization and successful surgery, the epileptogenic zone was associated with significant impulse responses. Significance The results suggest that the spike-triggered impulse response can provide valuable information about the neuronal networks that contribute to seizures using only interictal data. This technique will enable testing of specific hypotheses regarding functional connectivity in epilepsy and the relationship between functional properties and imaging findings. Beyond epilepsy, we expect that the impulse response could be more broadly applied as a measure of long-range functional connectivity in studies of cognition. PMID:26975603

Alcohol-Preferring Rats Show Goal Oriented Behaviour to Food Incentives but Are Neither Sign-Trackers Nor Impulsive.

PubMed

Peña-Oliver, Yolanda; Giuliano, Chiara; Economidou, Daina; Goodlett, Charles R; Robbins, Trevor W; Dalley, Jeffrey W; Everitt, Barry J

2015-01-01

Drug addiction is often associated with impulsivity and altered behavioural responses to both primary and conditioned rewards. Here we investigated whether selectively bred alcohol-preferring (P) and alcohol-nonpreferring (NP) rats show differential levels of impulsivity and conditioned behavioural responses to food incentives. P and NP rats were assessed for impulsivity in the 5-choice serial reaction time task (5-CSRTT), a widely used translational task in humans and other animals, as well as Pavlovian conditioned approach to measure sign- and goal-tracking behaviour. Drug-naïve P and NP rats showed similar levels of impulsivity on the 5-CSRTT, assessed by the number of premature, anticipatory responses, even when the waiting interval to respond was increased. However, unlike NP rats, P rats were faster to enter the food magazine and spent more time in this area. In addition, P rats showed higher levels of goal-tracking responses than NP rats, as measured by the number of magazine nose-pokes during the presentation of a food conditioned stimulus. By contrast, NP showed higher levels of sign-tracking behaviour than P rats. Following a 4-week exposure to intermittent alcohol we confirmed that P rats had a marked preference for, and consumed more alcohol than, NP rats, but were not more impulsive when re-tested in the 5-CSRTT. These findings indicate that high alcohol preferring and drinking P rats are neither intrinsically impulsive nor do they exhibit impulsivity after exposure to alcohol. However, P rats do show increased goal-directed behaviour to food incentives and this may be associated with their strong preference for alcohol.

Differences in head impulse test results due to analysis techniques.

PubMed

Cleworth, Taylor W; Carpenter, Mark G; Honegger, Flurin; Allum, John H J

2017-01-01

Different analysis techniques are used to define vestibulo-ocular reflex (VOR) gain between eye and head angular velocity during the video head impulse test (vHIT). Comparisons would aid selection of gain techniques best related to head impulse characteristics and promote standardisation. Compare and contrast known methods of calculating vHIT VOR gain. We examined lateral canal vHIT responses recorded from 20 patients twice within 13 weeks of acute unilateral peripheral vestibular deficit onset. Ten patients were tested with an ICS Impulse system (GN Otometrics) and 10 with an EyeSeeCam (ESC) system (Interacoustics). Mean gain and variance were computed with area, average sample gain, and regression techniques over specific head angular velocity (HV) and acceleration (HA) intervals. Results for the same gain technique were not different between measurement systems. Area and average sample gain yielded equally lower variances than regression techniques. Gains computed over the whole impulse duration were larger than those computed for increasing HV. Gain over decreasing HV was associated with larger variances. Gains computed around peak HV were smaller than those computed around peak HA. The median gain over 50-70 ms was not different from gain around peak HV. However, depending on technique used, the gain over increasing HV was different from gain around peak HA. Conversion equations between gains obtained with standard ICS and ESC methods were computed. For low gains, the conversion was dominated by a constant that needed to be added to ESC gains to equal ICS gains. We recommend manufacturers standardize vHIT gain calculations using 2 techniques: area gain around peak HA and peak HV.

An advanced real-time digital signal processing system for linear systems emulation, with special emphasis on network and acoustic response characterization

NASA Astrophysics Data System (ADS)

Gaydecki, Patrick; Fernandes, Bosco

2003-11-01

A fast digital signal processing (DSP) system is described that can perform real-time emulation of a wide variety of linear audio-bandwidth systems and networks, such as reverberant spaces, musical instrument bodies and very high order filter networks. The hardware design is based upon a Motorola DSP56309 operating at 110 million multiplication-accumulations per second and a dual-channel 24 bit codec with a maximum sampling frequency of 192 kHz. High level software has been developed to express complex vector frequency responses as both infinite impulse response (IIR) and finite impulse response (FIR) coefficients, in a form suitable for real-time convolution by the firmware installed in the DSP system memory. An algorithm has also been devised to express IIR filters as equivalent FIR structures, thereby obviating the potential instabilities associated with recursive equations and negating the traditional deficiencies of FIR filters respecting equivalent analogue designs. The speed and dynamic range of the system is such that, when sampling at 48 kHz, the frequency response can be specified to a spectral precision of 22 Hz when sampling at 10 kHz, this resolution increases to 0.9 Hz. Moreover, it is also possible to control the phase of any frequency band with a theoretical precision of 10-5 degrees in all cases. The system has been applied in the study of analogue filter networks, real-time Hilbert transformation, phase-shift systems and musical instrument body emulation, where it is providing valuable new insights into the understanding of psychoacoustic mechanisms.

Reflective-impulsive style and conceptual tempo in a gross motor task.

PubMed

Keller, J; Ripoll, H

2001-06-01

The reflective-impulsive construct refers to responses made slowly or quickly in a situation with high uncertainty. Children who are labeled "reflective" take a longer time to respond and make few errors, whereas "impulsive" children are fast and inaccurate. Although the validity of the test and the definition of reflective-impulsive style are well accepted, whether such respond fast or slow to all tasks is questioned. Some children do not fit the dichotomy. Two other groups arise, the fast-accurate and the slow-inaccurate. The response styles of 86 boys, ages 5, 7, and 9 years performing a gross motor task, i.e., hitting a ball with a racquet, were studied. Analysis indicated that the slowest children on the Matching Familiar Figures Test can be faster than the fastest ones and remain more accurate. As the definition of the reflective-impulsive style is based on time, the reflective ones might better be viewed as children who can adapt the response time to the context and thus be more efficient at problem-solving.

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.

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

Neural Correlates and Connectivity underlying Stress-related Impulse Control Difficulties in Alcoholism

PubMed Central

Seo, Dongju; Lacadie, Cheryl M.; Sinha, Rajita

2016-01-01

BACKGROUND Stress triggers impulsive and addictive behaviors, and alcoholism has been frequently associated with increased stress sensitivity and impulse control problems. However, neural correlates underlying the link between alcoholism and impulsivity in the context of stress in patients with alcohol use disorders (AUD) have not been well studied. METHOD The current study investigated neural correlates and connectivity patterns associated with impulse control difficulties in abstinent AUD patients. Using functional magnetic resonance imaging, brain responses of 37 AUD inpatients and 37 demographically-matched healthy controls were examined during brief individualized imagery trials of stress, alcohol-cue and neutral-relaxing conditions. Stress-related impulsivity was measured using a subscale score of impulse control problems from Difficulties in Emotion Regulation Scale (DERS). RESULTS Impulse control difficulties in AUD patients were significantly associated with hypoactive response to stress in the ventromedial prefrontal cortex (VmPFC), right caudate, and left lateral PFC (LPFC) compared to the neutral condition (p<0.01, whole-brain corrected). These regions were used as seed regions to further examine the connectivity patterns with other brain regions. With the VmPFC seed, AUD patients showed reduced connectivity with the anterior cingulate cortex (ACC) compared to controls, which are core regions of emotion regulation, suggesting AUD patients’ decreased ability to modulate emotional response under distressed state. With the right caudate seed, patients showed increased connectivity with the right motor cortex, suggesting increased tendency toward habitually driven behaviors. With the left LPFC seed, decreased connectivity with the dorsomedial PFC (DmPFC), but increased connectivity with sensory and motor cortices were found in AUD patients compared to controls (p<0.05, whole-brain corrected). Reduced connectivity between the left LPFC and DmPFC was further associated with increased stress-induced anxiety in AUD patients (p<0.05, with adjusted Bonferroni correction). CONCLUSION Hypoactive response to stress and altered connectivity in key emotion regulatory regions may account for greater stress-related impulse control problems in alcoholism. PMID:27501356

Neural Correlates and Connectivity Underlying Stress-Related Impulse Control Difficulties in Alcoholism.

PubMed

Seo, Dongju; Lacadie, Cheryl M; Sinha, Rajita

2016-09-01

Stress triggers impulsive and addictive behaviors, and alcoholism has been frequently associated with increased stress sensitivity and impulse control problems. However, neural correlates underlying the link between alcoholism and impulsivity in the context of stress in patients with alcohol use disorders (AUD) have not been well studied. This study investigated neural correlates and connectivity patterns associated with impulse control difficulties in abstinent AUD patients. Using functional magnetic resonance imaging, brain responses of 37 AUD inpatients, and 37 demographically matched healthy controls were examined during brief individualized imagery trials of stress, alcohol cue, and neutral-relaxing conditions. Stress-related impulsivity was measured using a subscale score of impulse control problems from Difficulties in Emotion Regulation Scale. Impulse control difficulties in AUD patients were significantly associated with hypo-active response to stress in the ventromedial prefrontal cortex (VmPFC), right caudate, and left lateral PFC (LPFC) compared to the neutral condition (p < 0.01, whole-brain corrected). These regions were used as seed regions to further examine the connectivity patterns with other brain regions. With the VmPFC seed, AUD patients showed reduced connectivity with the anterior cingulate cortex compared to controls, which are core regions of emotion regulation, suggesting AUD patients' decreased ability to modulate emotional response under distressed state. With the right caudate seed, patients showed increased connectivity with the right motor cortex, suggesting increased tendency toward habitually driven behaviors. With the left LPFC seed, decreased connectivity with the dorsomedial PFC (DmPFC), but increased connectivity with sensory and motor cortices were found in AUD patients compared to controls (p < 0.05, whole-brain corrected). Reduced connectivity between the left LPFC and DmPFC was further associated with increased stress-induced anxiety in AUD patients (p < 0.05, with adjusted Bonferroni correction). Hypo-active response to stress and altered connectivity in key emotion regulatory regions may account for greater stress-related impulse control problems in alcoholism. Copyright © 2016 by the Research Society on Alcoholism.

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

Impulse position control algorithms for nonlinear systems

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

Sesekin, A. N., E-mail: sesekin@list.ru; Institute of Mathematics and Mechanics, Ural Division of Russian Academy of Sciences, 16 S. Kovalevskaya, Ekaterinburg, 620990; Nepp, A. N., E-mail: anepp@urfu.ru

2015-11-30

The article is devoted to the formalization and description of impulse-sliding regime in nonlinear dynamical systems that arise in the application of impulse position controls of a special kind. The concept of trajectory impulse-sliding regime formalized as some limiting network element Euler polygons generated by a discrete approximation of the impulse position control This paper differs from the previously published papers in that it uses a definition of solutions of systems with impulse controls, it based on the closure of the set of smooth solutions in the space of functions of bounded variation. The need for the study of suchmore » regimes is the fact that they often arise when parry disturbances acting on technical or economic control system.« less

The hearing threshold of a harbor porpoise (Phocoena phocoena) for impulsive sounds (L).

PubMed

Kastelein, Ronald A; Gransier, Robin; Hoek, Lean; de Jong, Christ A F

2012-08-01

The distance at which harbor porpoises can hear underwater detonation sounds is unknown, but depends, among other factors, on the hearing threshold of the species for impulsive sounds. Therefore, the underwater hearing threshold of a young harbor porpoise for an impulsive sound, designed to mimic a detonation pulse, was quantified by using a psychophysical technique. The synthetic exponential pulse with a 5 ms time constant was produced and transmitted by an underwater projector in a pool. The resulting underwater sound, though modified by the response of the projection system and by the pool, exhibited the characteristic features of detonation sounds: A zero to peak sound pressure level of at least 30 dB (re 1 s(-1)) higher than the sound exposure level, and a short duration (34 ms). The animal's 50% detection threshold for this impulsive sound occurred at a received unweighted broadband sound exposure level of 60 dB re 1 μPa(2)s. It is shown that the porpoise's audiogram for short-duration tonal signals [Kastelein et al., J. Acoust. Soc. Am. 128, 3211-3222 (2010)] can be used to estimate its hearing threshold for impulsive sounds.

Women with elevated food addiction symptoms show accelerated reactions, but no impaired inhibitory control, in response to pictures of high-calorie food-cues.

PubMed

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

2012-12-01

Addictive behaviors are accompanied by a lack of inhibitory control, specifically when individuals are confronted with substance-related cues. Thus, we expected women with symptoms of food addiction to be impaired in inhibitory control, when confronted with palatable, high-calorie food-cues. Female college students (N=50) were divided in low and high food addiction groups based on the symptom count of the Yale Food Addiction Scale. Participants performed a Go/No-go-task with high-calorie food-cues or neutral pictures presented behind the targets. Self-reported impulsivity was also assessed. The high food addiction group had faster reaction times in response to food-cues as compared to neutral cues and reported higher attentional impulsivity than the low food addiction group. Commission and omission errors did not differ between groups or picture types. Hence, women with food addiction symptoms reported higher attentional impulsivity and reacted faster in response to food-cues, although neither increased self-reported motor impulsivity nor impaired behavioral inhibition was found. Food addiction symptoms seem to be related to attentional aspects of impulsivity but not other facets of impulsivity. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

Obsessive-compulsive disorder, impulse control disorders and drug addiction: common features and potential treatments.

PubMed

Fontenelle, Leonardo F; Oostermeijer, Sanne; Harrison, Ben J; Pantelis, Christos; Yücel, Murat

2011-05-07

The basic concepts underlying compulsive, impulsive and addictive behaviours overlap, which may help explain why laymen use these expressions interchangeably. Although there has been a large research effort to better characterize and disentangle these behaviours, clinicians and scientists are still unable to clearly differentiate them. Accordingly, obsessive-compulsive disorder (OCD), impulse control disorders (ICD) and substance-related disorders (SUD) overlap on different levels, including phenomenology, co-morbidity, neurocircuitry, neurocognition, neurochemistry and family history. In this review we summarize these issues with particular emphasis on the role of the opioid system in the pathophysiology and treatment of OCD, ICD and SUD. We postulate that with progression and chronicity of OCD, the proportion of the OCD-related behaviours (e.g. checking, washing, ordering and hoarding, among others) that are driven by impulsive 'rash' processes increase as involvement of more ventral striatal circuits becomes prominent. In contrast, as SUD and ICD progress, the proportion of the SUD- and ICD-related behaviours that are driven by compulsive 'habitual' processes increase as involvement of more dorsal striatal circuits become prominent. We are not arguing that, with time, ICD becomes OCD or vice versa. Instead, we are proposing that these disorders may acquire qualities of the other with time. In other words, while patients with ICD/SUD may develop 'compulsive impulsions', patients with OCD may exhibit 'impulsive compulsions'. There are many potential implications of our model. Theoretically, OCD patients exhibiting impulsive or addictive features could be managed with drugs that address the quality of the underlying drives and the involvement of neural systems. For example, agents for the reduction or prevention of relapse of addiction (e.g. heavy drinking), which modulate the cortico-mesolimbic dopamine system through the opioid (e.g. buprenorphine and naltrexone), glutamate (e.g. topiramate), serotonin (e.g. ondansetron) or γ-aminobutyric acid (e.g. baclofen and topiramate) systems, may prove to show some benefit in certain forms of OCD. Based on the available evidence, we suggest that the treatment of patients with these disorders must account for alterations in the underlying motivations and neurobiology of the condition. We provide an initial guide to the specific treatments that future clinical trials might consider in patients with OCD. For example, it might be wise to test naltrexone in patients with co-morbid SUD and ICD, topiramate in patients with co-morbid ICD and eating disorders, and baclofen in patients with co-morbid Tourette's syndrome. These trials could also include scales aimed at assessing underlying impulsivity (e.g. Barratt Impulsiveness Scale) to check whether this construct might predict response to drugs acting on the reward system. © 2011 Adis Data Information BV. All rights reserved.

Suicidality in Bipolar Disorder: The Role of Emotion-Triggered Impulsivity.

PubMed

Johnson, Sheri L; Carver, Charles S; Tharp, Jordan A

2017-04-01

A growing body of research suggests that impulsive responses to emotion more robustly predict suicidality than do other forms of impulsivity. This issue has not yet been examined within bipolar disorder, however. Participants diagnosed with bipolar I disorder (n = 133) and control participants (n = 110) diagnosed with no mood or psychotic disorder completed self-report measures of emotion-triggered impulsivity (Negative and Positive Urgency Scales) and interviews concerning lifetime suicidality. Analyses examined the effects of emotion-triggered impulsivity alone and in combination with gender, age of onset, depression severity, comorbid anxiety, comorbid substance use, and medication. A history of suicide ideation and attempts, as well as self-harm, were significantly more common in the bipolar disorder group compared with the control group. Impulsive responses to positive emotions related to suicide ideation, attempts, and self-harm within the bipolar group. Findings extend research on the importance of emotion-triggered impulsivity to a broad range of key outcomes within bipolar disorder. The discussion focuses on limitations and potential clinical implications. © 2016 The American Association of Suicidology.

Heavy drinking, impulsivity and attentional narrowing following alcohol cue exposure.

PubMed

Hicks, Joshua A; Fields, Sherecce; Davis, William E; Gable, Philip A

2015-08-01

Research shows that alcohol-related stimuli have the propensity to capture attention among individuals motivated to consume alcohol. Research has further demonstrated that impulsive individuals are especially prone to this type of attentional bias. Recently, it is suggested that alcohol cue exposure can also produce a general narrowing of attention consistent with the activation of approach motivational states. Based on previous models of addiction and recent research on the activation of approach motivational states, we predicted that impulsive individuals would demonstrate a constriction of attentional focus in response to alcohol cue exposure. Participants (n = 392) completed a task assessing attentional breadth in response to alcohol and non-alcohol cues, followed by measures of alcohol use and impulsivity. The findings revealed that impulsivity scores predicted narrowing of attentional scope following the presentation of alcohol cues for heavier drinkers but not for light drinkers. These results suggest that impulsive individuals who drink more heavily demonstrate a narrowing of attention in the presence of alcohol-related incentive cues. Implications for how these findings might account for the link between impulsivity and alcohol use and misuse are discussed.

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.

Dopamine D1 and D3 Receptors Modulate Heroin-Induced Cognitive Impairment through Opponent Actions in Mice

PubMed Central

Zhu, Yongsheng; Wang, Yunpeng; Wei, Shuguang; Zhang, Hongbo; Yan, Peng; Li, Yunxiao; Qiao, Xiaomeng; Yin, Fangyuan

2017-01-01

Abstract Background: Chronic abuse of heroin leads to long-lasting and complicated cognitive impairment. Dopamine receptors are critically involved in the impulsive drug-driven behavior and the altered attention, processing speed, and mental flexibility that are associated with higher relapse rates. However, the effects of the different dopamine receptors and their possible involvement in heroin-induced cognitive impairment remain unclear. Methods: The 5-choice serial reaction time task was used to investigate the profiles of heroin-induced cognitive impairment in mice. The expression levels of dopamine D1- and D2-like receptors in the prefrontal cortex, nucleus accumbens, and caudate-putamen were determined. The effects of dopamine receptors on heroin-induced impulsivity in the 5-choice serial reaction time task were examined by agonist/antagonist treatment on D1 or D3 receptor mutant mice. Results: Systemic heroin administration influences several variables in the 5-choice serial reaction time task, most notably premature responses, a measure of motor impulsivity. These behavioral impairments are associated with increased D1 receptor and decreased D3 receptor mRNA and protein levels in 3 observed brain areas. The heroin-evoked increase in premature responses is mimicked by a D1 agonist and prevented by a D1 antagonist or genetic ablation of the D1 receptor gene. In contrast, a D3 agonist decreases both basal and heroin-evoked premature responses, while genetic ablation of the D3 receptor gene results in increased basal and heroin-evoked premature responses. Conclusions: Heroin-induced impulsive behavior in the 5-choice serial reaction time task is oppositely modulated by D1 and D3 receptor activation. The D1 receptors in the cortical-mesolimbic region play an indispensable role in modulating such behaviors. PMID:27815417

Ice Sheet Roughness Estimation Based on Impulse Responses Acquired in the Global Ice Sheet Mapping Orbiter Mission

NASA Astrophysics Data System (ADS)

Niamsuwan, N.; Johnson, J. T.; Jezek, K. C.; Gogineni, P.

2008-12-01

The Global Ice Sheet Mapping Orbiter (GISMO) mission was developed to address scientific needs to understand the polar ice subsurface structure. This NASA Instrument Incubator Program project is a collaboration between Ohio State University, the University of Kansas, Vexcel Corporation and NASA. The GISMO design utilizes an interferometric SAR (InSAR) strategy in which ice sheet reflected signals received by a dual-antenna system are used to produce an interference pattern. The resulting interferogram can be used to filter out surface clutter so as to reveal the signals scattered from the base of the ice sheet. These signals are further processed to produce 3D-images representing basal topography of the ice sheet. In the past three years, the GISMO airborne field campaigns that have been conducted provide a set of useful data for studying geophysical properties of the Greenland ice sheet. While topography information can be obtained using interferometric SAR processing techniques, ice sheet roughness statistics can also be derived by a relatively simple procedure that involves analyzing power levels and the shape of the radar impulse response waveforms. An electromagnetic scattering model describing GISMO impulse responses has previously been proposed and validated. This model suggested that rms-heights and correlation lengths of the upper surface profile can be determined from the peak power and the decay rate of the pulse return waveform, respectively. This presentation will demonstrate a procedure for estimating the roughness of ice surfaces by fitting the GISMO impulse response model to retrieved waveforms from selected GISMO flights. Furthermore, an extension of this procedure to estimate the scattering coefficient of the glacier bed will be addressed as well. Planned future applications involving the classification of glacier bed conditions based on the derived scattering coefficients will also be described.

[Neurobiological aspects of reactive and proactive violence in antisocial personality disorder and "psychopathy"].

PubMed

Roth, Gerhard; Strüber, Daniel

2009-01-01

Impulsive-reactive violent offenders show increased autonomic activity in response to negative emotional and threatening stimuli. A volume reduction and/or activity decrease of frontal brain structures associated with impulse control and the regulation of fear and anger are likewise found in combination with a fear-related hyperactivity of the amygdala. In addition, impulsive aggression is facilitated by variants of gene polymorphisms influencing the serotonergic system. Conversely, proactive-instrumental violent offender with psychopathy, who are characterized by a lack of empathy and remorse, demonstrate an autonomic hypo-responsivity as well as dysfunctions of the amygdala and of cortical regions related to empathic and social behavior. Developmentally, aggressive children exhibit temperamental differences from early childhood on that are characteristic of a developmental pathway towards either reactive or proactive violence later in life. Exposure to negative environmental factors like ineffective parenting or childhood maltreatment has been related to a heightened risk for developing reactive violence. A developmental trajectory of proactive violence, however, has been related to a mostly genetically determined callous unemotional temperament of the child that disrupts the parental socialization efforts during childhood.

Context influences decision-making in boys with attention-deficit/hyperactivity disorder: A comparison of traditional and novel choice-impulsivity paradigms.

PubMed

Patros, Connor H G; Alderson, R Matt; Lea, Sarah E; Tarle, Stephanie J

2017-02-01

Attention-deficit/hyperactivity disorder (ADHD) is characterized by an impaired ability to maintain attention and/or hyperactivity/impulsivity. Impulsivity is frequently defined as the preference for small, immediate rewards over larger, delayed rewards, and has been associated with a variety of negative outcomes such as risky behavior and academic difficulty. Extant studies have uniformly utilized the traditional paradigm of presenting two response choices, which limits the generalization of findings to scenarios in which children/adolescents are faced with dichotomous decisions. The current study is the first to examine the effect of manipulating the number of available response options on impulsive decision-making in boys with and without ADHD. A total of 39 boys (ADHD = 16, typically developing [TD] = 23) aged 8-12 years completed a traditional two-choice impulsivity task and a novel five-choice impulsivity task to examine the effect of manipulating the number of choice responses (two vs five) on impulsive decision-making. A five-choice task was utilized as it presents a more continuous array of choice options when compared to the typical two-choice task, and is comparable given its methodological similarity to the two-choice task. Results suggested that boys with ADHD were significantly more impulsive than TD boys during the two-choice task, but not during the five-choice task. Collectively, these findings suggest that ADHD-related impulsivity is not ubiquitous, but rather dependent on variation in demands and/or context. Further, these findings highlight the importance of examining ADHD-related decision-making within the context of alternative paradigms, as the exclusive utilization of two-choice tasks may promote inaccurate conceptualizations of the disorder.

Does oxygen delivery explain interindividual variation in forearm critical impulse?

PubMed

Kellawan, J Mikhail; Bentley, Robert F; Bravo, Michael F; Moynes, Jackie S; Tschakovsky, Michael E

2014-11-01

Within individuals, critical power appears sensitive to manipulations in O2 delivery. We asked whether interindividual differences in forearm O2 delivery might account for a majority of the interindividual differences in forearm critical force impulse (critical impulse), the force analog of critical power. Ten healthy men (24.6 ± 7.10 years) completed a maximal effort rhythmic handgrip exercise test (1 sec contraction-2 sec relaxation) for 10 min. The average of contraction impulses over the last 30 sec quantified critical impulse. Forearm brachial artery blood flow (FBF; echo and Doppler ultrasound) and mean arterial pressure (MAP; finger photoplethysmography) were measured continuously. O2 delivery (FBF arterial oxygen content (venous blood [hemoglobin] and oxygen saturation from pulse oximetry)) and forearm vascular conductance (FVC; FBF·MAP(-1)) were calculated. There was a wide range in O2 delivery (59.98-121.15 O2 mL·min(-1)) and critical impulse (381.5-584.8 N) across subjects. During maximal effort exercise, O2 delivery increased rapidly, plateauing well before the declining forearm impulse and explained most of the interindividual differences in critical impulse (r(2) = 0.85, P < 0.01). Both vasodilation (r(2) = 0.64, P < 0.001) and the exercise pressor response (r(2) = 0.33, P < 0.001) independently contributed to interindividual differences in FBF. In conclusion, interindividual differences in forearm O2 delivery account for most of the interindividual variation in critical impulse. Furthermore, individual differences in pressor response play an important role in determining differences in O2 delivery in addition to vasodilation. The mechanistic origins of this vasodilatory and pressor response heterogeneity across individuals remain to be determined. © 2014 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Does oxygen delivery explain interindividual variation in forearm critical impulse?

PubMed Central

Kellawan, J. Mikhail; Bentley, Robert F.; Bravo, Michael F.; Moynes, Jackie S.; Tschakovsky, Michael E.

2014-01-01

Abstract Within individuals, critical power appears sensitive to manipulations in O2 delivery. We asked whether interindividual differences in forearm O2 delivery might account for a majority of the interindividual differences in forearm critical force impulse (critical impulse), the force analog of critical power. Ten healthy men (24.6 ± 7.10 years) completed a maximal effort rhythmic handgrip exercise test (1 sec contraction‐2 sec relaxation) for 10 min. The average of contraction impulses over the last 30 sec quantified critical impulse. Forearm brachial artery blood flow (FBF; echo and Doppler ultrasound) and mean arterial pressure (MAP; finger photoplethysmography) were measured continuously. O2 delivery (FBF arterial oxygen content (venous blood [hemoglobin] and oxygen saturation from pulse oximetry)) and forearm vascular conductance (FVC; FBF·MAP−1) were calculated. There was a wide range in O2 delivery (59.98–121.15 O2 mL·min−1) and critical impulse (381.5–584.8 N) across subjects. During maximal effort exercise, O2 delivery increased rapidly, plateauing well before the declining forearm impulse and explained most of the interindividual differences in critical impulse (r2 = 0.85, P < 0.01). Both vasodilation (r2 = 0.64, P < 0.001) and the exercise pressor response (r2 = 0.33, P < 0.001) independently contributed to interindividual differences in FBF. In conclusion, interindividual differences in forearm O2 delivery account for most of the interindividual variation in critical impulse. Furthermore, individual differences in pressor response play an important role in determining differences in O2 delivery in addition to vasodilation. The mechanistic origins of this vasodilatory and pressor response heterogeneity across individuals remain to be determined. PMID:25413323

Personality differences in the susceptibility to stress-eating: The influence of emotional control and impulsivity.

PubMed

Van Blyderveen, Sherry; Lafrance, Adele; Emond, Michael; Kosmerly, Stacey; O'Connor, Megan; Chang, Felicia

2016-12-01

Stress has been associated with deviations from typical eating patterns, with respect to both food choice and overall caloric intake. Both increases and decreases in dietary intake have been previously noted in response to stress. The purpose of the present study was to determine whether the affect regulation strategies of emotional control and impulsivity predict susceptibility to eating in response to stress. Specifically, it was anticipated that emotional suppression would predict decreases in caloric intake, whereas impulsivity would predict increases in caloric intake, in response to a stressor. Participants were randomly assigned to view either a video designed to elicit stress or a control video. Food was provided during the video and the amount and type of food consumed was measured. Participants' nutritional intake was greater in the stress condition than in the control condition. One aspect of affect regulation, impulsivity, moderated this relationship, with a tendency for greater impulsivity to be associated with greater caloric intake in the stress condition. The degree of negative affect that participants experienced in the stress condition predicted food choice and overall caloric intake. Both emotional control and impulsivity moderated the relationship between negative affect and both food choice and caloric intake in the stress condition. The present study highlights the importance of considering the personality attributes of both impulsivity and emotional suppression in understanding stress eating. Copyright © 2016. Published by Elsevier Ltd.

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.

[Electrical response of inner membrane structures of corynebacteria during electrotransformation].

PubMed

Tiurin, M V; Voroshilova, E B; Rostova, Iu G; Oparina, N Iu; Gusiatiner, M M

1998-01-01

The efficiency of the electrotransformation of intact cells of corynebacteria by a solitary impulse with a complex shape amounted to 10(6) transformants/microgram of plasmid pNV1 DNA at an electric field strength of 14.2 kW/cm; the voltage-current curve of the cell samples was nonlinear. Under these conditions, the structure of the electric current impulse passing intact cells or protoplasts included oscillations characterized by increasing amplitude and a duration of 170 microseconds, which were not detected in the structure of the electric current impulses at field strengths insufficient for obtaining transformants. These changes in the impulse shape suggest the involvement of internal closed membrane structures in the electrical response of cells to the exogenous electric impulse. Most probably, under conditions of electrical treatment optimal for transformation, electropores are formed in the intracellular membranes of corynebacteria.

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.

Endogenous Opioid Signaling in the Medial Prefrontal Cortex is Required for the Expression of Hunger-Induced Impulsive Action.

PubMed

Selleck, Ryan A; Lake, Curtis; Estrada, Viridiana; Riederer, Justin; Andrzejewski, Matthew; Sadeghian, Ken; Baldo, Brian A

2015-09-01

Opioid transmission and dysregulated prefrontal cortex (PFC) activity have both been implicated in the inhibitory-control deficits associated with addiction and binge-type eating disorders. What remains unknown, however, is whether endogenous opioid transmission within the PFC modulates inhibitory control. Here, we compared intra-PFC opioid manipulations with a monoamine manipulation (d-amphetamine), in two sucrose-reinforced tasks: progressive ratio (PR), which assays the motivational value of an incentive, and differential reinforcement of low response rates (DRLs), a test of inhibitory control. Intra-PFC methylnaloxonium (M-NX, a limited diffusion opioid antagonist) was given to rats in a 'low-drive' condition (2-h food deprivation), and also after a motivational shift to a 'high-drive' condition (18-h food deprivation). Intra-PFC DAMGO (D-[Ala2,N-MePhe4, Gly-ol]-enkephalin; a μ-opioid agonist) and d-amphetamine were also tested in both tasks, under the low-drive condition. Intra-PFC M-NX nearly eliminated impulsive action in DRL engendered by hunger, at a dose (1 μg) that significantly affected neither hunger-induced PR enhancement nor hyperactivity. At a higher dose (3 μg), M-NX eliminated impulsive action and returned PR breakpoint to low-drive levels. Conversely, intra-PFC DAMGO engendered 'high-drive-like' effects: enhancement of PR and impairment of DRL performance. Intra-PFC d-amphetamine failed to produce effects in either task. These results establish that endogenous PFC opioid transmission is both necessary and sufficient for the expression of impulsive action in a high-arousal, high-drive appetitive state, and that PFC-based opioid systems enact functionally unique effects on food impulsivity and motivation relative to PFC-based monoamine systems. Opioid antagonists may represent effective treatments for a range of psychiatric disorders with impulsivity features.

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.

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

Gambling behavior in Parkinson's Disease: Impulsivity, reward mechanism and cortical brain oscillations.

PubMed

Balconi, Michela; Angioletti, Laura; Siri, Chiara; Meucci, Nicoletta; Pezzoli, Gianni

2018-03-20

Psychopathological components, such as reward sensitivity and impulsivity, and dopaminergic treatment are crucial characteristics related to the development of Pathological Gambling (PG) in Parkinson's Disease (PD). The aim of the present study is to investigate the differences in decision-making in PD patients with or without PG considering both neurophysiological and behavioral aspects. The IOWA Gambling Task (IGT) and electroencephalographic (EEG) activity were considered to elucidate the decision and post-feedback processes in PG. The sample included fifty-two PD patients, divided in three groups: 17 PD patients with active gambling behavior (PD Gamblers, PDG); 15 PD patients who remitted from PG (PD Non-Gamblers, PDNG); and a Control Group (CG) composed by 20 patients with PD only. EEG and IGT performance were recorded during decision and post-feedback phase. Results showed worse performance and an increase of the low frequency bands in the frontal area for the PDG group compared to the other two groups. In addition, higher BAS (Behavioral Activation System) and BIS-11 (Barratt Impulsiveness Scale) personality components were correlated to groups' behavioral response. These results show an anomalous behavioral (IGT) and cortical response of PDG patients related to their inability to use adequate control mechanisms during a decision-making task where reward mechanisms (BAS) and impulsivity (BIS-11) are relevant. Copyright © 2018 Elsevier B.V. All rights reserved.

First Stage of a Highly Reliable Reusable Launch System

NASA Technical Reports Server (NTRS)

Kloesel, Kurt J.; Pickrel, Jonathan B.; Sayles, Emily L.; Wright, Michael; Marriott, Darin; Holland, Leo; Kuznetsov, Stephen

2009-01-01

Electromagnetic launch assist has the potential to provide a highly reliable reusable first stage to a space access system infrastructure at a lower overall cost. This paper explores the benefits of a smaller system that adds the advantages of a high specific impulse air-breathing stage and supersonic launch speeds. The method of virtual specific impulse is introduced as a tool to emphasize the gains afforded by launch assist. Analysis shows launch assist can provide a 278-s virtual specific impulse for a first-stage solid rocket. Additional trajectory analysis demonstrates that a system composed of a launch-assisted first-stage ramjet plus a bipropellant second stage can provide a 48-percent gross lift-off weight reduction versus an all-rocket system. The combination of high-speed linear induction motors and ramjets is identified, as the enabling technologies and benchtop prototypes are investigated. The high-speed response of a standard 60 Hz linear induction motor was tested with a pulse width modulated variable frequency drive to 150 Hz using a 10-lb load, achieving 150 mph. A 300-Hz stator-compensated linear induction motor was constructed and static-tested to 1900 lbf average. A matching ramjet design was developed for use on the 300-Hz linear induction motor.

On the limits of Kagan's impulsive reflective distinction.

PubMed

Jones, B; McIntyre, L

1976-05-01

A logical analysis is made of the Matching Familiar Figures (MFF) Test on the basis of which children have been classified as "impulsive" or "reflective." The reflective strategy is implicitly preferred to the impulsive because the reflective child makes fewer errors though generally taking longer to make his first response. We show that the test allows the choice of a number of "game plans" and speed-accuracy tradeoffs which in practice may not be very different. Error rates may not indicate perceptual sensitivity, in any case, since sensitivity and response factors may be confounded in the error rate. Using a visual running-memory-span task to avoid the inherent difficulties of the MFF test, we found that children previously classified on the basis of that test as impulsive or reflective did not differ in recognition accuracy but did differ in response bias and response latency. Accuracy and bias are estimated by way of Luce's choice theory (Luce, 1963), and the results are discussed in those terms.

The effect of spinal manipulation impulse duration on spine neuromechanical responses

PubMed Central

Pagé, Isabelle; Nougarou, François; Dugas, Claude; Descarreaux, Martin

2014-01-01

Introduction: Spinal manipulation therapy (SMT) is characterized by specific kinetic and kinematic parameters that can be modulated. The purpose of this study is to investigate fundamental aspects of SMT dose-physiological response relation in humans by varying SMT impulse duration. Methods: Twenty healthy adults were subjected to four different SMT force-time profiles delivered by a servo-controlled linear actuator motor and differing in their impulse duration. EMG responses of the left and right thoracic paraspinal muscles (T6 and T8 levels) and vertebral displacements of T7 and T8 were evaluated for all SMT phases. Results: Significant differences in paraspinal EMG were observed during the “Thrust phase” and immediately after (“Post-SMT1”) (all T8 ps < 0.01 and T6 during the thrust ps < 0.05). Sagittal vertebral displacements were similar across all conditions (p > 0.05). Conclusion: Decreasing SMT impulse duration leads to a linear increase in EMG response of thoracic paraspinal during and following the SMT thrust. PMID:24932018

Implementation and extension of the impulse transfer function method for future application to the space shuttle project. Volume 1: Analysis and correlation studies

NASA Technical Reports Server (NTRS)

Mantus, M.; Pardo, H.

1973-01-01

Computer programming, data processing, and a correlation study that employed data collected in the first phase test were used to demonstrate that standard test procedures and equipment could be used to collect a significant number of transfer functions from tests of the Lunar Module test article LTA-11. The testing consisted of suspending the vehicle from the apex fittings of the outrigger trusses through a set of air springs to simulate the free-free state. Impulsive loadings were delivered, one at a time, at each of the landing gear's attachment points, in three mutually perpendicular directions; thus a total of 36 impulses were applied to the vehicle. Time histories of each pulse were recorded on magnetic tape along with 40 channels of strain gage response and 28 channels of accelerometer response. Since an automated data processing system was not available, oscillograph playbacks were made of all 2400 time histories as a check on the validity of the data taken. In addition, one channel of instrumentation was processed to determine its response to a set of forcing functions from a prior LTA-11 drop test. This prediction was compared with drop test results as a first measure of accuracy.

Impulsive control of stochastic systems with applications in chaos control, chaos synchronization, and neural networks.

PubMed

Li, Chunguang; Chen, Luonan; Aihara, Kazuyuki

2008-06-01

Real systems are often subject to both noise perturbations and impulsive effects. In this paper, we study the stability and stabilization of systems with both noise perturbations and impulsive effects. In other words, we generalize the impulsive control theory from the deterministic case to the stochastic case. The method is based on extending the comparison method to the stochastic case. The method presented in this paper is general and easy to apply. Theoretical results on both stability in the pth mean and stability with disturbance attenuation are derived. To show the effectiveness of the basic theory, we apply it to the impulsive control and synchronization of chaotic systems with noise perturbations, and to the stability of impulsive stochastic neural networks. Several numerical examples are also presented to verify the theoretical results.

Linear response theory for annealing of radiation damage in semiconductor devices

NASA Technical Reports Server (NTRS)

Litovchenko, Vitaly

1988-01-01

A theoretical study of the radiation/annealing response of MOS ICs is described. Although many experiments have been performed in this field, no comprehensive theory dealing with radiation/annealing response has been proposed. Many attempts have been made to apply linear response theory, but no theoretical foundation has been presented. The linear response theory outlined here is capable of describing a broad area of radiation/annealing response phenomena in MOS ICs, in particular, both simultaneous irradiation and annealing, as well as short- and long-term annealing, including the case when annealing is nearing completion. For the first time, a simple procedure is devised to determine the response function from experimental radiation/annealing data. In addition, this procedure enables us to study the effect of variable temperature and dose rate, effects which are of interest in spaceflight. In the past, the shift in threshold potential due to radiation/annealing has usually been assumed to depend on one variable: the time lapse between an impulse dose and the time of observation. While such a suggestion of uniformity in time is certainly true for a broad range of radiation annealing phenomena, it may not hold for some ranges of the variables of interest (temperature, dose rate, etc.). A response function is projected which is dependent on two variables: the time of observation and the time of the impulse dose. This dependence on two variables allows us to extend the theory to the treatment of a variable dose rate. Finally, the linear theory is generalized to the case in which the response is nonlinear with impulse dose, but is proportional to some impulse function of dose. A method to determine both the impulse and response functions is presented.

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.

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.

Simple Climate Model Evaluation Using Impulse Response Tests

NASA Astrophysics Data System (ADS)

Schwarber, A.; Hartin, C.; Smith, S. J.

2017-12-01

Simple climate models (SCMs) are central tools used to incorporate climate responses into human-Earth system modeling. SCMs are computationally inexpensive, making them an ideal tool for a variety of analyses, including consideration of uncertainty. Despite their wide use, many SCMs lack rigorous testing of their fundamental responses to perturbations. Here, following recommendations of a recent National Academy of Sciences report, we compare several SCMs (Hector-deoclim, MAGICC 5.3, MAGICC 6.0, and the IPCC AR5 impulse response function) to diagnose model behavior and understand the fundamental system responses within each model. We conduct stylized perturbations (emissions and forcing/concentration) of three different chemical species: CO2, CH4, and BC. We find that all 4 models respond similarly in terms of overall shape, however, there are important differences in the timing and magnitude of the responses. For example, the response to a BC pulse differs over the first 20 years after the pulse among the models, a finding that is due to differences in model structure. Such perturbation experiments are difficult to conduct in complex models due to internal model noise, making a direct comparison with simple models challenging. We can, however, compare the simplified model response from a 4xCO2 step experiment to the same stylized experiment carried out by CMIP5 models, thereby testing the ability of SCMs to emulate complex model results. This work allows an assessment of how well current understanding of Earth system responses are incorporated into multi-model frameworks by way of simple climate models.

[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.

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

Quickbird Satellite in-orbit Modulation Transfer Function (MTF) Measurement Using Edge, Pulse and Impulse Methods for Summer 2003

NASA Technical Reports Server (NTRS)

Helder, Dennis; Choi, Taeyoung; Rangaswamy, Manjunath

2005-01-01

The spatial characteristics of an imaging system cannot be expressed by a single number or simple statement. However, the Modulation Transfer Function (MTF) is one approach to measure the spatial quality of an imaging system. Basically, MTF is the normalized spatial frequency response of an imaging system. The frequency response of the system can be evaluated by applying an impulse input. The resulting impulse response is termed the Point Spread function (PSF). This function is a measure of the amount of blurring present in the imaging system and is itself a useful measure of spatial quality. An underlying assumption is that the imaging system is linear and shift-independent. The Fourier transform of the PSF is called the Optical Transfer Function (OTF) and the normalized magnitude of the OTF is the MTF. In addition to using an impulse input, a knife-edge in technique has also been used in this project. The sharp edge exercises an imaging system at all spatial frequencies. The profile of an edge response from an imaging system is called an Edge Spread Function (ESF). Differentiation of the ESF results in a one-dimensional version of the Point Spread Function (PSF). Finally, MTF can be calculated through use of Fourier transform of the PSF as stated previously. Every image includes noise in some degree which makes MTF of PSF estimation more difficult. To avoid the noise effects, many MTF estimation approaches use smooth numerical models. Historically, Gaussian models and Fermi functions were applied to reduce the random noise in the output profiles. The pulse-input method was used to measure the MTF of the Landsat Thematic Mapper (TM) using 8th order even functions over the San Mateo Bridge in San Francisco, California. Because the bridge width was smaller than the 30-meter ground sample distance (GSD) of the TM, the Nyquist frequency was located before the first zero-crossing point of the sinc function from the Fourier transformation of the bridge pulse. To avoid the zero-crossing points in the frequency domain from a pulse, the pulse width should be less than the width of two pixels (or 2 GSD's), but the short extent of the pulse results in a poor signal-to-noise ratio. Similarly, for a high-resolution satellite imaging system such as Quickbird, the input pulse width was critical because of the zero crossing points and noise present in the background area. It is important, therefore, that the width of the input pulse be appropriately sized. Finally, the MTF was calculated by taking ratio between Fourier transform of output and Fourier transform of input. Regardless of whether the edge, pulse and impulse target method is used, the orientation of the targets is critical in order to obtain uniformly spaced sub-pixel data points. When the orientation is incorrect, sample data points tend to be located in clusters that result in poor reconstruction of the edge or pulse profiles. Thus, a compromise orientation must be selected so that all spectral bands can be accommodated. This report continues by outlining the objectives in Section 2, procedures followed in Section 3, descriptions of the field campaigns in Section 4, results in Section 5, and a brief summary in Section 6.

Effects of Displacement Damage on the Time-Resolved Gain and Bandwidth of a Low Breakdown Voltage Si Avalanche Photodiode

NASA Technical Reports Server (NTRS)

Laird, Jamie S.; Onoda, Shinobu; Hirao, Toshio; Becker, Heidi; Johnston, Allan; Laird, Jamie S.; Itoh, Hisayoshi

2006-01-01

Effects of displacement damage and ionization damage induced by gamma irradiation on the dark current and impulse response of a high-bandwidth low breakdown voltage Si Avalanche Photodiode has been investigated using picosecond laser microscopy. At doses as high as 10Mrad (Si) minimal alteration in the impulse response and bandwidth were observed. However, dark current measurements also performed with and without biased irradiation exhibit anomalously large damage factors for applied biases close to breakdown. The absence of any degradation in the impulse response is discussed as are possible mechanisms for higher dark current damage factors observed for biased irradiation.

Predictors of response to Systems Training for Emotional Predictability and Problem Solving (STEPPS) for borderline personality disorder: an exploratory study.

PubMed

Black, D W; Allen, J; St John, D; Pfohl, B; McCormick, B; Blum, N

2009-07-01

Few predictors of treatment outcome or early discontinuation have been identified in persons with borderline personality disorder (BPD). The aim of the study was to examine the relationship between baseline clinical variables and treatment response and early discontinuation in a randomized controlled trial of System Training for Emotional Predictability and Problem Solving, a new cognitive group treatment. Improvement was rated using the Zanarini Rating Scale for BPD, the Clinical Global Impression Scale, the Global Assessment Scale and the Beck Depression Inventory. Subjects were assessed during the 20 week trial and a 1-year follow-up. Higher baseline severity was associated with greater improvement in global functioning and BPD-related symptoms. Higher impulsivity was predictive of early discontinuation. Optimal improvement was associated with attending > or = 15 sessions. Subjects likely to improve have the more severe BPD symptoms at baseline, while high levels of impulsivity are associated with early discontinuation.

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

Adaptive Identification and Control of Flow-Induced Cavity Oscillations

NASA Technical Reports Server (NTRS)

Kegerise, M. A.; Cattafesta, L. N.; Ha, C.

2002-01-01

Progress towards an adaptive self-tuning regulator (STR) for the cavity tone problem is discussed in this paper. Adaptive system identification algorithms were applied to an experimental cavity-flow tested as a prerequisite to control. In addition, a simple digital controller and a piezoelectric bimorph actuator were used to demonstrate multiple tone suppression. The control tests at Mach numbers of 0.275, 0.40, and 0.60 indicated approx. = 7dB tone reductions at multiple frequencies. Several different adaptive system identification algorithms were applied at a single freestream Mach number of 0.275. Adaptive finite-impulse response (FIR) filters of orders up to N = 100 were found to be unsuitable for modeling the cavity flow dynamics. Adaptive infinite-impulse response (IIR) filters of comparable order better captured the system dynamics. Two recursive algorithms, the least-mean square (LMS) and the recursive-least square (RLS), were utilized to update the adaptive filter coefficients. Given the sample-time requirements imposed by the cavity flow dynamics, the computational simplicity of the least mean squares (LMS) algorithm is advantageous for real-time control.

Women with borderline personality disorder do not show altered BOLD responses during response inhibition.

PubMed

van Eijk, Julia; Sebastian, Alexandra; Krause-Utz, Annegret; Cackowski, Sylvia; Demirakca, Traute; Biedermann, Sarah V; Lieb, Klaus; Bohus, Martin; Schmahl, Christian; Ende, Gabriele; Tüscher, Oliver

2015-12-30

Impulsivity is central to borderline personality disorder (BPD). Response inhibition, addressing the ability to suppress or stop actions, is one aspect of behavioral impulse control which is frequently used to assess impulsivity. BPD patients display deficits in response inhibition under stress condition or negative emotions. We assessed whether response inhibition and its neural underpinnings are impaired in BPD when tested in an emotionally neutral setting and when co-morbid attention-deficit/hyperactivity disorder (ADHD) is excluded. To this end, we studied response inhibition in unmedicated BPD patients and healthy controls (HC) in two independent samples using functional magnetic resonance imaging during Simon-, Go/nogo-, and Stopsignal tasks. BPD patients and HC did not differ significantly in their performance in the Go/nogo and the Stopsignal tasks. Response interference in the Simon task was increased in BPD patients in one sample, but this could not be replicated in the second sample. In both samples, no significant differences in brain activation patterns during any of the tasks were present while the neural impulse control network was robustly activated during the inhibition tasks in both groups. Our results provide evidence that under emotionally neutral conditions response inhibition is not impaired in patients with BPD without co-occurring ADHD. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

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

Impulse response and spatio-temporal wave-packets: The common feature of rogue waves, tsunami, and transition to turbulence

NASA Astrophysics Data System (ADS)

Bhaumik, Swagata; Sengupta, Tapan K.

2017-12-01

Here, we present the impulse response of the canonical zero pressure gradient boundary layer from the dynamical system approach. The fundamental physical mechanism of the impulse response is in creation of a spatio-temporal wave-front (STWF) by a localized, time-impulsive wall excitation of the boundary layer. The present research is undertaken to explain the unit process of diverse phenomena in geophysical fluid flows and basic hydrodynamics. Creation of a tsunami has been attributed to localized events in the ocean-bed caused by earthquakes, landslides, or volcanic eruptions, whose manifestation is in the run up to the coast by surface waves of massive amplitude but of very finite fetch. Similarly rogue waves have often been noted; a coherent account of the same is yet to appear, although some explanations have been proposed. Our studies in both two- and three-dimensional frameworks in Sengupta and Bhaumik ["Onset of turbulence from the receptivity stage of fluid flows," Phys. Rev. Lett. 107(15), 154501 (2011)] and Bhaumik and Sengupta ["Precursor of transition to turbulence: Spatiotemporal wave front," Phys. Rev. E 89(4), 043018 (2014)] have shown that the STWF provides the central role for causing transition to turbulence by reproducing carefully conducted transition experiments. Here, we furthermore relax the condition of time behavior and use a Dirac-delta wall excitation for the impulse response. The present approach is not based on any simplification of the governing Navier-Stokes equation (NSE), which is unlike solving a nonlinear shallow water equation and/or nonlinear Schrödinger equation. The full nonlinear Navier-Stokes equation (NSE) is solved here using high accuracy dispersion relation preserving numerical schemes and using appropriate formulation of the NSE which minimizes error. The adopted numerical methods and formulation have been extensively validated with respect to various external and internal 2D and 3D flow problems. We also present results from the Orr-Sommerfeld equation to show that the origin of the STWF is via a linear mechanism. Nonlinearity and nonparallelism play the central role in causing these phenomena of geophysics and transition to turbulence.

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.

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

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.

Pulsed Electric Propulsion Thrust Stand Calibration Method

NASA Technical Reports Server (NTRS)

Wong, Andrea R.; Polzin, Kurt A.; Pearson, J. Boise

2011-01-01

The evaluation of the performance of any propulsion device requires the accurate measurement of thrust. While chemical rocket thrust is typically measured using a load cell, the low thrust levels associated with electric propulsion (EP) systems necessitate the use of much more sensitive measurement techniques. The design and development of electric propulsion thrust stands that employ a conventional hanging pendulum arm connected to a balance mechanism consisting of a secondary arm and variable linkage have been reported in recent publications by Polzin et al. These works focused on performing steady-state thrust measurements and employed a static analysis of the thrust stand response. In the present work, we present a calibration method and data that will permit pulsed thrust measurements using the Variable Amplitude Hanging Pendulum with Extended Range (VAHPER) thrust stand. Pulsed thrust measurements are challenging in general because the pulsed thrust (impulse bit) occurs over a short timescale (typically 1 micros to 1 millisecond) and cannot be resolved directly. Consequently, the imparted impulse bit must be inferred through observation of the change in thrust stand motion effected by the pulse. Pulsed thrust measurements have typically only consisted of single-shot operation. In the present work, we discuss repetition-rate pulsed thruster operation and describe a method to perform these measurements. The thrust stand response can be modeled as a spring-mass-damper system with a repetitive delta forcing function to represent the impulsive action of the thruster.

Modeling Attitude Dynamics in Simulink: A Study of the Rotational and Translational Motion of a Spacecraft Given Torques and Impulses Generated by RMS Hand Controllers

NASA Technical Reports Server (NTRS)

Mauldin, Rebecca H.

2010-01-01

In order to study and control the attitude of a spacecraft, it is necessary to understand the natural motion of a body in orbit. Assuming a spacecraft to be a rigid body, dynamics describes the complete motion of the vehicle by the translational and rotational motion of the body. The Simulink Attitude Analysis Model applies the equations of rigid body motion to the study of a spacecraft?s attitude in orbit. Using a TCP/IP connection, Matlab reads the values of the Remote Manipulator System (RMS) hand controllers and passes them to Simulink as specified torque and impulse profiles. Simulink then uses the governing kinematic and dynamic equations of a rigid body in low earth orbit (LE0) to plot the attitude response of a spacecraft for five seconds given known applied torques and impulses, and constant principal moments of inertia.

Monoamine Oxidase A (MAOA) Genotype Predicts Greater Aggression Through Impulsive Reactivity to Negative Affect

PubMed Central

Chester, David S.; DeWall, C. Nathan; Derefinko, Karen J.; Estus, Steven; Peters, Jessica R.; Lynam, Donald R.; Jiang, Yang

2015-01-01

Low functioning MAOA genotypes have been reliably linked to increased reactive aggression, yet the psychological mechanisms of this effect remain largely unknown. The low functioning MAOA genotype’s established link to diminished inhibition and greater reactivity to conditions of negative affect suggest that negative urgency, the tendency to act impulsively in the context of negative affect, may fill this mediating role. Such MAOA carriers may have higher negative urgency, which may in turn predict greater aggressive responses to provocation. To test these hypotheses, 277 female and male participants were genotyped for an MAOA SNP yet to be linked to aggression (rs1465108), and then reported their negative urgency and past aggressive behavior. We replicated the effect of the low functioning MAOA genotype on heightened aggression, which was mediated by greater negative urgency. These results suggest that disrupted serotonergic systems predispose individuals towards aggressive behavior by increasing impulsive reactivity to negative affect. PMID:25637908

A Lie algebraic condition for exponential stability of discrete hybrid systems and application to hybrid synchronization.

PubMed

Zhao, Shouwei

2011-06-01

A Lie algebraic condition for global exponential stability of linear discrete switched impulsive systems is presented in this paper. By considering a Lie algebra generated by all subsystem matrices and impulsive matrices, when not all of these matrices are Schur stable, we derive new criteria for global exponential stability of linear discrete switched impulsive systems. Moreover, simple sufficient conditions in terms of Lie algebra are established for the synchronization of nonlinear discrete systems using a hybrid switching and impulsive control. As an application, discrete chaotic system's synchronization is investigated by the proposed method.

Annoyance due to simulated blade-slap noise

NASA Technical Reports Server (NTRS)

Powell, C. A.

1978-01-01

The effects of several characteristics of blade slap noise on annoyance response were studied. These characteristics or parameters were the sound pressure level of the continuous noise used to simulate helicopter broadband noise, the ratio of impulse peak to broadband noise or crest factor, the number of pressure excursions comprising an impulse event, the rise and fall time of the individual impulses, and the repetition frequency of the impulses. Analyses were conducted to determine the correlation between subjective response and various physical measures for the range of parameters studied. A small but significant improvement in the predictive ability of PNL was provided by an A-weighted crest factor correlation. No significant improvement in predictive ability was provided by a rate correction.

Understanding Computation of Impulse Response in Microwave Software Tools

ERIC Educational Resources Information Center

Potrebic, Milka M.; Tosic, Dejan V.; Pejovic, Predrag V.

2010-01-01

In modern microwave engineering curricula, the introduction of the many new topics in microwave industrial development, or of software tools for design and simulation, sometimes results in students having an inadequate understanding of the fundamental theory. The terminology for and the explanation of algorithms for calculating impulse response in…

Specific cognitive-neurophysiological processes predict impulsivity in the childhood attention-deficit/hyperactivity disorder combined subtype.

PubMed

Bluschke, A; Roessner, V; Beste, C

2016-04-01

Attention-deficit/hyperactivity disorder (ADHD) is one of the most prevalent neuropsychiatric disorders in childhood. Besides inattention and hyperactivity, impulsivity is the third core symptom leading to diverse and serious problems. However, the neuronal mechanisms underlying impulsivity in ADHD are still not fully understood. This is all the more the case when patients with the ADHD combined subtype (ADHD-C) are considered who are characterized by both symptoms of inattention and hyperactivity/impulsivity. Combining high-density electroencephalography (EEG) recordings with source localization analyses, we examined what information processing stages are dysfunctional in ADHD-C (n = 20) compared with controls (n = 18). Patients with ADHD-C made more impulsive errors in a Go/No-go task than healthy controls. Neurophysiologically, different subprocesses from perceptual gating to attentional selection, resource allocation and response selection processes are altered in this patient group. Perceptual gating, stimulus-driven attention selection and resource allocation processes were more pronounced in ADHD-C, are related to activation differences in parieto-occipital networks and suggest attentional filtering deficits. However, only response selection processes, associated with medial prefrontal networks, predicted impulsive errors in ADHD-C. Although the clinical picture of ADHD-C is complex and a multitude of processing steps are altered, only a subset of processes seems to directly modulate impulsive behaviour. The present findings improve the understanding of mechanisms underlying impulsivity in patients with ADHD-C and might help to refine treatment algorithms focusing on impulsivity.

Detecting the Spectrum of the Atlantic's Thermo-haline Circulation: Deconvolved Climate Proxies Show How Polar Climates Communicate

NASA Astrophysics Data System (ADS)

Reischmann, Elizabeth; Yang, Xiao; Rial, José

2014-05-01

Deconvolution is widely used in a wide variety of scientific fields, including its significant use in seismology, as a tool to recover real input from a system's impulse response and output. Our research uses spectral division deconvolution in the context of studying the impulse response of the possible relationship between the nonlinear climates of the Polar Regions by using select δ18O ice cores from both poles. This is feasible in spite of the fact that the records may be the result of nonlinear processes because the two polar climates are synchronized for the period studied, forming a Hilbert transform pair. In order to perform this analysis, the age models of three Greenland and four Antarctica records have been matched using a Monte Carlo method with the methane-matched pair GRIP and BYRD as a basis of calculations. For all of the twelve resulting pairs, various deconvolutions schemes (Weiner, Damped Least Squares, Tikhonov, Truncated Singular Value Decomposition) give consistent, quasi-periodic, impulse responses of the system. Multitaper analysis then demonstrates strong, millennia scale, quasi-periodic oscillations in these system responses with a range of 2,500 to 1,000 years. However, these results are directionally dependent, with the transfer function from north to south differing from that of south north. High amplitude power peaks at 5,000 to 1,7000 years characterize the former, while the latter contains peaks at 2,500 to 1,700 years. These predominant periodicities are also found in the data, some of which have been identified as solar forcing, but others of which may indicate internal oscillations of the climate system (1.6-1.4ky). The approximately 1,500 year period transfer function, which does not have a corresponding solar forcing, may indicate one of these internal periodicities of the system, perhaps even indicating the long-term presence of the Deep Water circulation, also known as the thermo-haline circulation (THC). Simplified models of the polar climate fluctuations are shown to support these findings.

Generalized fluid impulse functions for oscillating marine structures

NASA Astrophysics Data System (ADS)

Janardhanan, K.; Price, W. G.; Wu, Y.

1992-03-01

A selection of generalized impulse response functions is presented for a variety of rigid and flexible marine structures (i.e. mono-hull, SWATH, floating drydock and twin dock, fixed flexible pile). These functions are determined from calculated and experimental frequency-dependent hydrodynamic data, and the characteristics of these data depend on the type of structure considered. This information is reflected in the shape and duration of the generalized impulse response functions which are pre-requisites for a generalized integro-differential mathematical model describing the dynamic behaviour of the structures to seaway excitation.

Error processing and response inhibition in excessive computer game players: an event-related potential study.

PubMed

Littel, Marianne; van den Berg, Ivo; Luijten, Maartje; van Rooij, Antonius J; Keemink, Lianne; Franken, Ingmar H A

2012-09-01

Excessive computer gaming has recently been proposed as a possible pathological illness. However, research on this topic is still in its infancy and underlying neurobiological mechanisms have not yet been identified. The determination of underlying mechanisms of excessive gaming might be useful for the identification of those at risk, a better understanding of the behavior and the development of interventions. Excessive gaming has been often compared with pathological gambling and substance use disorder. Both disorders are characterized by high levels of impulsivity, which incorporates deficits in error processing and response inhibition. The present study aimed to investigate error processing and response inhibition in excessive gamers and controls using a Go/NoGo paradigm combined with event-related potential recordings. Results indicated that excessive gamers show reduced error-related negativity amplitudes in response to incorrect trials relative to correct trials, implying poor error processing in this population. Furthermore, excessive gamers display higher levels of self-reported impulsivity as well as more impulsive responding as reflected by less behavioral inhibition on the Go/NoGo task. The present study indicates that excessive gaming partly parallels impulse control and substance use disorders regarding impulsivity measured on the self-reported, behavioral and electrophysiological level. Although the present study does not allow drawing firm conclusions on causality, it might be that trait impulsivity, poor error processing and diminished behavioral response inhibition underlie the excessive gaming patterns observed in certain individuals. They might be less sensitive to negative consequences of gaming and therefore continue their behavior despite adverse consequences. © 2012 The Authors, Addiction Biology © 2012 Society for the Study of Addiction.

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.

Waveform design for detection of weapons based on signature exploitation

NASA Astrophysics Data System (ADS)

Ahmad, Fauzia; Amin, Moeness G.; Dogaru, Traian

2010-04-01

We present waveform design based on signature exploitation techniques for improved detection of weapons in urban sensing applications. A single-antenna monostatic radar system is considered. Under the assumption of exact knowledge of the target orientation and, hence, known impulse response, matched illumination approach is used for optimal target detection. For the case of unknown target orientation, we analyze the target signatures as random processes and perform signal-to-noise-ratio based waveform optimization. Numerical electromagnetic modeling is used to provide the impulse responses of an AK-47 assault rifle for various target aspect angles relative to the radar. Simulation results depict an improvement in the signal-to-noise-ratio at the output of the matched filter receiver for both matched illumination and stochastic waveforms as compared to a chirp waveform of the same duration and energy.

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.

Efficient multidimensional regularization for Volterra series estimation

NASA Astrophysics Data System (ADS)

Birpoutsoukis, Georgios; Csurcsia, Péter Zoltán; Schoukens, Johan

2018-05-01

This paper presents an efficient nonparametric time domain nonlinear system identification method. It is shown how truncated Volterra series models can be efficiently estimated without the need of long, transient-free measurements. The method is a novel extension of the regularization methods that have been developed for impulse response estimates of linear time invariant systems. To avoid the excessive memory needs in case of long measurements or large number of estimated parameters, a practical gradient-based estimation method is also provided, leading to the same numerical results as the proposed Volterra estimation method. Moreover, the transient effects in the simulated output are removed by a special regularization method based on the novel ideas of transient removal for Linear Time-Varying (LTV) systems. Combining the proposed methodologies, the nonparametric Volterra models of the cascaded water tanks benchmark are presented in this paper. The results for different scenarios varying from a simple Finite Impulse Response (FIR) model to a 3rd degree Volterra series with and without transient removal are compared and studied. It is clear that the obtained models capture the system dynamics when tested on a validation dataset, and their performance is comparable with the white-box (physical) models.

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

Vibrational Responses Of Structures To Impulses

NASA Technical Reports Server (NTRS)

Zak, Michail A.

1990-01-01

Report discusses propagation of vibrations in structure in response to impulsive and/or concentrated loads. Effects of pulsed loads treated by analyzing propagation of characteristic vibrational waves explicitly through each member of structure. This wave-front analysis used in combination with usual finite-element modal analysis to obtain more accurate representation of overall vibrational behavior.

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.

A Brief Experimental Analysis of Reinforcer and Response Dimensions Related to Self-Control in an Outpatient Clinic

ERIC Educational Resources Information Center

Falcomata, Terry S.; Cooper-Brown, Linda J.; Wacker, David P.; Gardner, Andrew W.; Boelter, Eric W.

2010-01-01

We conducted an assessment of self-control and impulsivity with 9 children referred to an outpatient clinic for impulsive, inattentive, and hyperactive behaviors. Each condition of the assessment consisted of a choice between 2 concurrently presented math or writing tasks, with 1 alternative reflecting impulsive responding and 1 alternative…

MODEL SIMULATION STUDIES OF SCALE-DEPENDENT GAIN IN STREAM NUTRIENT ASSIMILATIVE CAPACITY RESULTING FROM IMPROVING NUTRIENT RETENTION METRICS

EPA Science Inventory

Considering the difficulty in measuring restoration success for nonpoint source pollutants, nutrient assimilative capacity (NAS) offers an attractive systems-based metric. Here NAS was defined using an impulse-response model of nitrate fate and transport. Eleven parameters were e...

Ten Ways To Provide a High-Quality Acoustical Environment in Schools.

ERIC Educational Resources Information Center

Siebein, Gary W.; Gold, Martin A.; Siebein, Glenn W.; Ermann, Michael G.

2000-01-01

A study used impulse response measures and observations in 10 Florida classrooms to develop 10 recommendations for improving the acoustical environment in schools. Recommendations include improving air-conditioning systems, limiting room volume, providing sound-absorbing surfaces, using carpeting, reducing distance between teachers and students,…

Impulse Response Operators for Structural Complexes

DTIC Science & Technology

1990-05-12

systems of the complex. The statistical energy analysis (SEA) is one such a device [ 13, 14]. The rendering of SEA from equation (21) and/or (25) lies...Propagation.] 13. L. Cremer, M. Heckl, and E.E. Ungar 1973 Structure-Borne Sound (Springer Verlag). 14. R. H. Lyon 1975 Statistical Energy Analysis of

Linear response to nonstationary random excitation.

NASA Technical Reports Server (NTRS)

Hasselman, T.

1972-01-01

Development of a method for computing the mean-square response of linear systems to nonstationary random excitation of the form given by y(t) = f(t) x(t), in which x(t) = a stationary process and f(t) is deterministic. The method is suitable for application to multidegree-of-freedom systems when the mean-square response at a point due to excitation applied at another point is desired. Both the stationary process, x(t), and the modulating function, f(t), may be arbitrary. The method utilizes a fundamental component of transient response dependent only on x(t) and the system, and independent of f(t) to synthesize the total response. The role played by this component is analogous to that played by the Green's function or impulse response function in the convolution integral.

How partial reinforcement of food cues affects the extinction and reacquisition of appetitive responses. A new model for dieting success?

PubMed

van den Akker, Karolien; Havermans, Remco C; Bouton, Mark E; Jansen, Anita

2014-10-01

Animals and humans can easily learn to associate an initially neutral cue with food intake through classical conditioning, but extinction of learned appetitive responses can be more difficult. Intermittent or partial reinforcement of food cues causes especially persistent behaviour in animals: after exposure to such learning schedules, the decline in responding that occurs during extinction is slow. After extinction, increases in responding with renewed reinforcement of food cues (reacquisition) might be less rapid after acquisition with partial reinforcement. In humans, it may be that the eating behaviour of some individuals resembles partial reinforcement schedules to a greater extent, possibly affecting dieting success by interacting with extinction and reacquisition. Furthermore, impulsivity has been associated with less successful dieting, and this association might be explained by impulsivity affecting the learning and extinction of appetitive responses. In the present two studies, the effects of different reinforcement schedules and impulsivity on the acquisition, extinction, and reacquisition of appetitive responses were investigated in a conditioning paradigm involving food rewards in healthy humans. Overall, the results indicate both partial reinforcement schedules and, possibly, impulsivity to be associated with worse extinction performance. A new model of dieting success is proposed: learning histories and, perhaps, certain personality traits (impulsivity) can interfere with the extinction and reacquisition of appetitive responses to food cues and they may be causally related to unsuccessful dieting. Copyright © 2014 Elsevier Ltd. All rights reserved.

Figure–ground discrimination behavior in Drosophila. I. Spatial organization of wing-steering responses

PubMed Central

Fox, Jessica L.; Aptekar, Jacob W.; Zolotova, Nadezhda M.; Shoemaker, Patrick A.; Frye, Mark A.

2014-01-01

The behavioral algorithms and neural subsystems for visual figure–ground discrimination are not sufficiently described in any model system. The fly visual system shares structural and functional similarity with that of vertebrates and, like vertebrates, flies robustly track visual figures in the face of ground motion. This computation is crucial for animals that pursue salient objects under the high performance requirements imposed by flight behavior. Flies smoothly track small objects and use wide-field optic flow to maintain flight-stabilizing optomotor reflexes. The spatial and temporal properties of visual figure tracking and wide-field stabilization have been characterized in flies, but how the two systems interact spatially to allow flies to actively track figures against a moving ground has not. We took a systems identification approach in flying Drosophila and measured wing-steering responses to velocity impulses of figure and ground motion independently. We constructed a spatiotemporal action field (STAF) – the behavioral analog of a spatiotemporal receptive field – revealing how the behavioral impulse responses to figure tracking and concurrent ground stabilization vary for figure motion centered at each location across the visual azimuth. The figure tracking and ground stabilization STAFs show distinct spatial tuning and temporal dynamics, confirming the independence of the two systems. When the figure tracking system is activated by a narrow vertical bar moving within the frontal field of view, ground motion is essentially ignored despite comprising over 90% of the total visual input. PMID:24198267

Regional Gray Matter Density Associated with Cognitive Reflectivity–Impulsivity: Evidence from Voxel-Based Morphometry

PubMed Central

Yokoyama, Ryoichi; Nozawa, Takayuki; Takeuchi, Hikaru; Taki, Yasuyuki; Sekiguchi, Atsushi; Nouchi, Rui; Kotozaki, Yuka; Nakagawa, Seishu; Miyauchi, Carlos Makoto; Iizuka, Kunio; Shinada, Takamitsu; Yamamoto, Yuki; Hanawa, Sugiko; Araki, Tsuyoshi; Hashizume, Hiroshi; Kunitoki, Keiko; Hanihara, Mayu; Sassa, Yuko; Kawashima, Ryuta

2015-01-01

When faced with a problem or choice, humans can use two different strategies: “cognitive reflectivity,” which involves slow responses and fewer mistakes, or “cognitive impulsivity,” which comprises of quick responses and more mistakes. Different individuals use these two strategies differently. To our knowledge, no study has directly investigated the brain regions involved in reflectivity–impulsivity; therefore, this study focused on associations between these cognitive strategies and the gray matter structure of several brain regions. In order to accomplish this, we enrolled 776 healthy, right-handed individuals (432 men and 344 women; 20.7 ± 1.8 years) and used voxel-based morphometry with administration of a cognitive reflectivity–impulsivity questionnaire. We found that high cognitive reflectivity was associated with greater regional gray matter density in the ventral medial prefrontal cortex. Our finding suggests that this area plays an important role in defining an individual’s trait associated with reflectivity and impulsivity. PMID:25803809

A Review of Research on Impulsive Loading of Marine Composites

NASA Astrophysics Data System (ADS)

Porfiri, Maurizio; Gupta, Nikhil

Impulsive loading conditions, such as those produced by blast waves, are being increasingly recognized as relevant in marine applications. Significant research efforts are directed towards understanding the impulsive loading response of traditional naval materials, such as aluminum and steel, and advanced composites, such as laminates and sandwich structures. Several analytical studies are directed towards establishing predictive models for structural response and failure of marine structures under blast loading. In addition, experimental research efforts are focused on characterizing structural response to blast loading. The aim of this review is to provide a general overview of the state of the art on analytical and experimental studies in this field that can serve as a guideline for future research directions. Reported studies cover the Office of Naval Research-Solid Mechanics Program sponsored research along with other worldwide research efforts of relevance to marine applications. These studies have contributed to developing a fundamental knowledge of the mechanics of advanced materials subjected to impulsive loading, which is of interest to all Department of Defense branches.

Neurophysiological correlates of altered response inhibition in internet gaming disorder and obsessive-compulsive disorder: Perspectives from impulsivity and compulsivity

PubMed Central

Kim, Minah; Lee, Tak Hyung; Choi, Jung-Seok; Kwak, Yoo Bin; Hwang, Wu Jeong; Kim, Taekwan; Lee, Ji Yoon; Lim, Jae-A; Park, Minkyung; Kim, Yeon Jin; Kim, Sung Nyun; Kim, Dai Jin; Kwon, Jun Soo

2017-01-01

Although internet gaming disorder (IGD) and obsessive-compulsive disorder (OCD) represent opposite ends of the impulsivity and compulsivity dimensions, the two disorders share common neurocognitive deficits in response inhibition. However, the similarities and differences in neurophysiological features of altered response inhibition between IGD and OCD have not been investigated sufficiently. In total, 27 patients with IGD, 24 patients with OCD, and 26 healthy control (HC) subjects participated in a Go/NoGo task with electroencephalographic recordings. N2-P3 complexes elicited during Go and NoGo condition were analyzed separately and compared among conditions and groups. NoGo-N2 latency at the central electrode site was delayed in IGD group versus the HC group and correlated positively with the severity of internet game addiction and impulsivity. NoGo-N2 amplitude at the frontal electrode site was smaller in OCD patients than in IGD patients. These findings suggest that prolonged NoGo-N2 latency may serve as a marker of trait impulsivity in IGD and reduced NoGo-N2 amplitude may be a differential neurophysiological feature between OCD from IGD with regard to compulsivity. We report the first differential neurophysiological correlate of the altered response inhibition in IGD and OCD, which may be a candidate biomarker for impulsivity and compulsivity. PMID:28134318

"Missing links" in borderline personality disorder: loss of neural synchrony relates to lack of emotion regulation and impulse control.

PubMed

Williams, Leanne M; Sidis, Anna; Gordon, Evian; Meares, Russell A

2006-05-01

Symptoms of borderline personality disorder (BPD) may reflect distinct breakdowns in the integration of posterior and frontal brain networks. We used a high temporal resolution measure (40-Hz gamma phase synchrony) of brain activity to examine the connectivity of brain function in BPD. Unmedicated patients with BPD (n = 15) and age-and sex-matched healthy control subjects (n = 15) undertook a task requiring discrimination of salient from background tones. In response to salient stimuli, the magnitude and latency of peak gamma phase synchrony for early (0-150 ms post stimulus) and late (250-500 ms post stimulus) phases were calculated for frontal and posterior regions and for left and right hemispheres. We recorded skin conductance responses (SCRs) and reaction time (RT) simultaneously to examine the contribution of arousal and performance. Compared with controls, patients with BPD had a significant delay in early posterior gamma synchrony and a reduction in right hemisphere late gamma synchrony in response to salient stimuli. Both SCR onset and RT were also delayed in BPD, but independently from differences in synchrony. The delay in posterior synchrony was associated with cognitive symptoms, and reduced right hemisphere synchrony was associated with impulsivity. These findings suggest that distinct impairments in the functional connectivity of neural systems for orienting to salient input underlie core dimensions of cognitive disturbance and poor impulse control in BPD.

Electronic Imaging: Rochester Imaging Consortium, Abstracts of Research Topics Reported at the Annual Meeting of the Optical Society of America Held in San Jose, California on 3-8 November 1991

DTIC Science & Technology

1991-11-01

Nicholas George "Image Deblurring for Multiple-Point Impulse Responses," Bryan J. Stossel and Nicholas George 14. SUBJECT TERMS 15. NUMBER OF PAGES...Keith B. Farr Nicholas George Backscatter from a Tilted Rough Disc Donald J. Schertler Nicholas George Image Deblurring for Multiple-Point Impulse ...correlation components. Uf) c)z 0 CL C/) Ix I- z 0 0 LL C,z -J a 0l IMAGE DEBLURRING FOR MULTIPLE-POINT IMPULSE RESPONSES Bryan J. Stossel and Nicholas George

Eyes wide shopped: shopping situations trigger arousal in impulsive buyers.

PubMed

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

2014-01-01

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

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

PubMed

Giesen, Janneke C A H; Havermans, Remco C; Nederkoorn, Chantal; Jansen, Anita

2012-02-01

The present study investigated the effect of taxing high-energy dense products and subsidizing low-energy dense products on changes in calorie consumption. More specifically, we hypothesized that 'more impulsive' individuals were less influenced by such pricing strategies compared to 'less impulsive' individuals. Contrary to our hypothesis, results showed that 'more impulsive' individuals adjusted their calorie consumption with regard to price changes whereas 'less impulsive' participants were less influenced by price changes. Furthermore, taxing high-energy dense products was more successful in reducing calorie consumption than subsidizing low-energy dense products. Copyright © 2011 Elsevier Ltd. All rights reserved.

A numerical study on the limitations of modal Iwan models for impulsive excitations

NASA Astrophysics Data System (ADS)

Lacayo, Robert M.; Deaner, Brandon J.; Allen, Matthew S.

2017-03-01

Structures with mechanical joints are difficult to model accurately. Even if the natural frequencies of the system remain essentially constant, the damping introduced by the joints is often observed to change dramatically with amplitude. Although models for individual joints have been employed with some success, accurately modeling a structure with many joints remains a significant obstacle. To this end, Segalman proposed a modal Iwan model, which simplifies the analysis by modeling a system with a linear superposition of weakly-nonlinear, uncoupled single degree-of-freedom systems or modes. Given a simulation model with discrete joints, one can identify the model for each mode by selectively exciting each mode one at a time and observing how the transient response decays. However, in the environment of interest several modes may be excited simultaneously, such as in an experiment when an impulse is applied at a discrete point. In this work, the modal Iwan model framework is assessed numerically to understand how well it captures the dynamic response of typical structures with joints when they are excited with impulsive forces applied at point locations. This is done by comparing the effective natural frequency and modal damping of the uncoupled modal models with those of truth models that include nonlinear modal coupling. These concepts are explored for two structures, a simple spring-mass system and a finite element model of a beam, both of which contain physical Iwan elements to model joint nonlinearity. The results show that modal Iwan models can effectively capture the variations in frequency and damping with amplitude, which, for damping, can increase by as much as two orders of magnitude in the microslip regime. However, even in the microslip regime the accuracy of a modal Iwan model is found to depend on whether the mode in question is dominant in the response; in some cases the effective damping that the uncoupled model predicts is found to be in error by tens of percent. Nonetheless, the modal model captures the response qualitatively and is still far superior to a linear model.

Influence of intertrial interval on basal and drug-induced impulsive action in the 5-choice serial reaction time task: Effects of d-amphetamine and (±)-2,5-dimethoxy-4-iodoamphetamine (DOI).

PubMed

Fitzpatrick, Ciaràn M; Maric, Vojislav S; Bate, Simon T; Andreasen, Jesper T

2018-01-01

Impulsivity is a characteristic of a number of neuropsychiatric disorders such as attention-deficit/hyperactivity disorder. The 5-choice serial reaction time task (5-CSRTT) is a rodent paradigm extensively used to assess attention and impulsivity. Notably, 5-CSRTT studies do not typically account for the reduction in premature responding, the measure of impulsive action, occurring upon repeated exposure to test sessions with long or variable intertrial intervals (ITIs). This present 5-CSRTT study investigated the use of variable ITIs (5, 10 or 15s) across 15 test days (4 training days followed by 1 drug test day per week for three weeks) as previous experience had shown that 4 training days would be sufficient to induce consistent premature response levels in male C57BL/6J mice. Once a steady state was achieved, the effects of dextroamphetamine (AMPH) and (±)-2,5-dimethoxy-4-iodoamphetamine (DOI) were then assessed using a Latin-square design to determine whether pharmacological-induced impulsive actions depended on ITI length. Mice habituated to the variable ITI schedule after only 3days and showed consistently lower premature response levels until the end of the study. AMPH (p<0.05) and DOI (p<0.05) increased the percentage of premature responses at 15s ITI trials, while only DOI (p<0.05) increased impulsive action at 10s ITI trials. Additionally, DOI increased omission rates (p<0.001), mean correct latency (p<0.01), reward collection latency (p<0.001), and reduced the total attempted trials (p<0.001). In summary, we demonstrated that mice habituate to the variable ITI schedule, suggesting that using the variable ITI schedule during training allowed premature response rates to stabilize before commencing pharmacological testing. Moreover, in these habituated mice AMPH and DOI significantly enhanced impulsive action at the long ITI trials only. We propose that experimental design considerations can improve the sensitivity of the 5-CSRTT to detect pharmacologicallyinduced impulsive action. Copyright © 2017 Elsevier B.V. All rights reserved.

Dopamine D1 and D3 Receptors Modulate Heroin-Induced Cognitive Impairment through Opponent Actions in Mice.

PubMed

Zhu, Yongsheng; Wang, Yunpeng; Lai, Jianghua; Wei, Shuguang; Zhang, Hongbo; Yan, Peng; Li, Yunxiao; Qiao, Xiaomeng; Yin, Fangyuan

2017-03-01

Chronic abuse of heroin leads to long-lasting and complicated cognitive impairment. Dopamine receptors are critically involved in the impulsive drug-driven behavior and the altered attention, processing speed, and mental flexibility that are associated with higher relapse rates. However, the effects of the different dopamine receptors and their possible involvement in heroin-induced cognitive impairment remain unclear. The 5-choice serial reaction time task was used to investigate the profiles of heroin-induced cognitive impairment in mice. The expression levels of dopamine D1- and D2-like receptors in the prefrontal cortex, nucleus accumbens, and caudate-putamen were determined. The effects of dopamine receptors on heroin-induced impulsivity in the 5-choice serial reaction time task were examined by agonist/antagonist treatment on D1 or D3 receptor mutant mice. Systemic heroin administration influences several variables in the 5-choice serial reaction time task, most notably premature responses, a measure of motor impulsivity. These behavioral impairments are associated with increased D1 receptor and decreased D3 receptor mRNA and protein levels in 3 observed brain areas. The heroin-evoked increase in premature responses is mimicked by a D1 agonist and prevented by a D1 antagonist or genetic ablation of the D1 receptor gene. In contrast, a D3 agonist decreases both basal and heroin-evoked premature responses, while genetic ablation of the D3 receptor gene results in increased basal and heroin-evoked premature responses. Heroin-induced impulsive behavior in the 5-choice serial reaction time task is oppositely modulated by D1 and D3 receptor activation. The D1 receptors in the cortical-mesolimbic region play an indispensable role in modulating such behaviors. © The Author 2016. Published by Oxford University Press on behalf of CINP.

Linear Ordinary Differential Equations with Constant Coefficients. Revisiting the Impulsive Response Method Using Factorization

ERIC Educational Resources Information Center

Camporesi, Roberto

2011-01-01

We present an approach to the impulsive response method for solving linear constant-coefficient ordinary differential equations based on the factorization of the differential operator. The approach is elementary, we only assume a basic knowledge of calculus and linear algebra. In particular, we avoid the use of distribution theory, as well as of…

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.

A family of variable step-size affine projection adaptive filter algorithms using statistics of channel impulse response

NASA Astrophysics Data System (ADS)

Shams Esfand Abadi, Mohammad; AbbasZadeh Arani, Seyed Ali Asghar

2011-12-01

This paper extends the recently introduced variable step-size (VSS) approach to the family of adaptive filter algorithms. This method uses prior knowledge of the channel impulse response statistic. Accordingly, optimal step-size vector is obtained by minimizing the mean-square deviation (MSD). The presented algorithms are the VSS affine projection algorithm (VSS-APA), the VSS selective partial update NLMS (VSS-SPU-NLMS), the VSS-SPU-APA, and the VSS selective regressor APA (VSS-SR-APA). In VSS-SPU adaptive algorithms the filter coefficients are partially updated which reduce the computational complexity. In VSS-SR-APA, the optimal selection of input regressors is performed during the adaptation. The presented algorithms have good convergence speed, low steady state mean square error (MSE), and low computational complexity features. We demonstrate the good performance of the proposed algorithms through several simulations in system identification scenario.

Separation Control in a Multistage Compressor Using Impulsive Surface Injection

NASA Technical Reports Server (NTRS)

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

2006-01-01

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

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.

Anger and Impulsivity Among Japanese Adolescents: A Nationwide Representative Survey.

PubMed

Itani, Osamu; Kaneita, Yoshitaka; Munezawa, Takeshi; Ikeda, Maki; Osaki, Yoneatsu; Higuchi, Susumu; Kanda, Hideyuki; Nakagome, Sachi; Suzuki, Kenji; Ohida, Takashi

2016-07-01

This study aimed to clarify the prevalence of anger and impulsivity and its associated factors through a nationwide survey of junior and senior high school adolescent students in Japan. A self-administered questionnaire covering (1) personal data, (2) lifestyle, (3) mental health status, and (4) feelings of anger and impulsivity was distributed to junior and senior high school students in Japan. Among the total of 10,955 junior high schools and 5,115 senior high schools nationwide, 130 and 110 were randomly selected, respectively. Of those, 92 junior and 80 senior high schools participated in the survey. The survey period was from December 2008 to the end of January 2009. A total of 95,680 questionnaires were collected. After excluding invalid responses, the remaining 94,777 responses (response rate: 62.3%) were analyzed. From the questions regarding anger and impulsivity, 8.7% (95% CI, 8.5%-8.9%) and 7.5% (95% CI, 7.3%-7.7%) of the participants were considered to have experienced intense anger and impulsivity, respectively. Logistic regression analysis indicated that the odds ratios for experiencing intense feelings of anger were significantly higher (all P values < .05) among students who smoked, consumed alcohol, skipped breakfast, did not wish to go to university, had short sleep duration, had decreased positive feelings, had increased depressive feelings, or used mobile phones for longer hours. The odds ratios for experiencing intense impulsivity were significantly higher among students who smoked, consumed alcohol, skipped breakfast, did not participate in club activities, had short sleep duration, had decreased positive feelings, had increased depressive feelings, or used mobile phones for longer hours. The results suggest that healthy lifestyle habits, good sleep habits, and improved mental health are important for preventing intense feelings of anger and impulsivity among adolescents. © Copyright 2016 Physicians Postgraduate Press, Inc.

The Utility of Impulsive Bias and Altered Decision Making as Predictors of Drug Efficacy and Target Selection: Rethinking Behavioral Screening for Antidepressant Drugs.

PubMed

Marek, Gerard J; Day, Mark; Hudzik, Thomas J

2016-03-01

Cognitive dysfunction may be a core feature of major depressive disorder, including affective processing bias, abnormal response to negative feedback, changes in decision making, and increased impulsivity. Accordingly, a translational medicine paradigm predicts clinical action of novel antidepressants by examining drug-induced changes in affective processing bias. With some exceptions, these concepts have not been systematically applied to preclinical models to test new chemical entities. The purpose of this review is to examine whether an empirically derived behavioral screen for antidepressant drugs may screen for compounds, at least in part, by modulating an impulsive biasing of responding and altered decision making. The differential-reinforcement-of-low-rate (DRL) 72-second schedule is an operant schedule with a documented fidelity for discriminating antidepressant drugs from nonantidepressant drugs. However, a theoretical basis for this empirical relationship has been lacking. Therefore, this review will discuss whether response bias toward impulsive behavior may be a critical screening characteristic of DRL behavior requiring long inter-response times to obtain rewards. This review will compare and contrast DRL behavior with the five-choice serial reaction time task, a test specifically designed for assessing motoric impulsivity, with respect to psychopharmacological testing and the neural basis of distributed macrocircuits underlying these tasks. This comparison suggests that the existing empirical basis for the DRL 72-second schedule as a pharmacological screen for antidepressant drugs is complemented by a novel hypothesis that altering impulsive response bias for rodents trained on this operant schedule is a previously unrecognized theoretical cornerstone for this screening paradigm. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

Sex-specific attenuation of impulsive action by progesterone in a Go/No-go task for cocaine in rats

PubMed Central

Swalve, Natashia; Smethells, John R.; Younk, Rebecca; Mitchell, Jared; Dougen, Ben; Carroll, Marilyn E.

2018-01-01

Rationale Previous work indicated that progesterone (PRO) reduced impulsive choice for cocaine in female but not male rats (Smethells et al. 2016). Impulsive action, typically measured by responding for a reinforcer during a signaled period of nonavailability of natural reinforcers, predicts initiation and escalation of drug use in animals and humans. The present study examined impulsive action for cocaine using progesterone (PRO) in male and female rats trained on a Go/No-go task. Objective Rats were trained on a Go/No-go task to respond for cocaine infusions (0.4 mg/kg/inf). During the “Go” component, responding was reinforced on a VI 30-s schedule; whereas, during the “No-Go” component withholding a response was reinforced on a differential reinforcement of other behavior (DRO) 30-s schedule. A response during the No-go component reset the DRO timer and served as a measure of impulsive action. After baseline responding was established, rats were pretreated with vehicle (VEH) or PRO (0.5 mg/kg), and DRO resets and responding during the Go component for cocaine were compared in males vs. females. Results DRO resets were significantly lower following PRO treatment compared to VEH in female, but not male, rats. Response rates and overall infusions during the Go component were not significantly altered by PRO in either females or males. Conclusion Treatment with PRO resulted in a sex-specific reduction in impulsive action for cocaine, while not affecting cocaine self-administration. PMID:29018893

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

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.

Stopping at the sight of food - How gender and obesity impact on response inhibition.

PubMed

Mühlberg, Christoph; Mathar, David; Villringer, Arno; Horstmann, Annette; Neumann, Jane

2016-12-01

Recent research indicates that reduced inhibitory control is associated with higher body mass index (BMI), higher food craving and increased food intake. However, experimental evidence for the relationship between response inhibition and weight status is inconsistent and to date has been investigated predominantly in women. In the current study, 56 participants (26 obese, 30 lean; 27 female, 29 male) performed a Food Picture Rating Task followed by a Stop Signal Task where pictures of palatable high or low caloric food or non-food items were presented prior to the Go signal. We further assessed participants' self-reported eating behavior and trait impulsivity as potential factors influencing response inhibition, in particular within the food context. Independent of BMI, women showed significantly higher liking for low caloric food items than men. This was accompanied by shorter Stop Signal Reaction Times (SSRT) after high compared to low caloric food pictures for women, and shorter SSRT in women compared to men for high caloric food. No influence of gender on SSRT was observable outside of the food context. While SSRTs did not differ between obese and lean participants across the three picture categories, we found a moderating effect of trait impulsivity on the relationship between BMI and SSRT, specifically in the high caloric food context. Higher BMI was predictive of longer SSRT only for participants with low to normal trait impulsivity, pointing at a complex interplay between response inhibition, general impulsivity and weight status. Our results support the notion that individuals with obesity do not suffer from diminished response inhibition capacity per se. Rather, the ability to withhold a response depends on context and social norms, and strongly interacts with factors like gender and trait impulsivity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Changes in cocaine consumption are associated with fluctuations in self-reported impulsivity and gambling decision-making.

PubMed

Hulka, L M; Vonmoos, M; Preller, K H; Baumgartner, M R; Seifritz, E; Gamma, A; Quednow, B B

2015-10-01

In cross-sectional studies, cocaine users generally display elevated levels of self-reported and cognitive impulsivity. To what extent these impairments are stable v. variable markers of cocaine use disorder, and, thus, are pre-existing or drug-induced, has not yet been systematically investigated. We conducted a longitudinal study with cocaine users who changed or maintained their consumption intensity, measuring self-reported impulsivity with the Barratt Impulsiveness Scale (BIS-11), and cognitive impulsivity with the Rapid Visual Processing task (RVP), Iowa Gambling task (IGT), and Delay Discounting task (DD) at baseline and at 1-year follow-up. We assessed 48 psychostimulant-naive controls and 19 cocaine users with decreased, 19 users with increased, and 19 users with unchanged cocaine intake after 1 year as confirmed by hair analysis. Results of linear multilevel modelling showed significant group × time interactions for the BIS-11 total score and the IGT total card ratio. Increasers showed a trend for elevated scores, whereas decreasers exhibited reduced self-reported impulsivity scores within 1 year. Surprisingly, increasers' IGT performance was improved after 1 year, whereas decreasers' performance deteriorated. By contrast, neither RVP response bias B" nor DD total score showed substantial group × time interactions. Importantly, BIS-11 and DD revealed strong test-retest reliabilities. Self-reported impulsivity (BIS-11) and decision-making impulsivity (IGT) covary with changing cocaine use, whereas response bias and delay discounting remain largely unaffected. Thus, self-reported impulsivity and gambling decision-making were strongly state-dependent in a stimulant-using population and may be suitable to monitor treatment success, whereas delay of gratification was confirmed as a potential endophenotype of stimulant addiction.

The effects of physical activity on impulsive choice: Influence of sensitivity to reinforcement amount and delay

PubMed Central

Strickland, Justin C.; Feinstein, Max A.; Lacy, Ryan T.; Smith, Mark A.

2016-01-01

Impulsive choice is a diagnostic feature and/or complicating factor for several psychological disorders and may be examined in the laboratory using delay-discounting procedures. Recent investigators have proposed using quantitative measures of analysis to examine the behavioral processes contributing to impulsive choice. The purpose of this study was to examine the effects of physical activity (i.e., wheel running) on impulsive choice in a single-response, discrete-trial procedure using two quantitative methods of analysis. To this end, rats were assigned to physical activity or sedentary groups and trained to respond in a delay-discounting procedure. In this procedure, one lever always produced one food pellet immediately, whereas a second lever produced three food pellets after a 0, 10, 20, 40, or 80-second delay. Estimates of sensitivity to reinforcement amount and sensitivity to reinforcement delay were determined using (1) a simple linear analysis and (2) an analysis of logarithmically transformed response ratios. Both analyses revealed that physical activity decreased sensitivity to reinforcement amount and sensitivity to reinforcement delay. These findings indicate that (1) physical activity has significant but functionally opposing effects on the behavioral processes that contribute to impulsive choice and (2) both quantitative methods of analysis are appropriate for use in single-response, discrete-trial procedures. PMID:26964905

Impulse Response of the Ocean Floor Nonlinear Techniques for Measurement Enhancement

DTIC Science & Technology

1983-04-01

Although there is current interest in detection of broadband energy in the ocean, most ASW systems are designed for discrete frequency emissions from...M«U2CDZ«’TZ — n HHO I-" (- UJ*UJ0 uj.»>- Z-- 3^ II I/IO U OZ CL*Q.HH LOS-^+CN

Computerized design and generation of space-variant holographic filters. II - Applications of space-variant filters to optical computing

NASA Technical Reports Server (NTRS)

Ambs, P.; Fainman, Y.; Esener, S.; Lee, S. H.

1988-01-01

Holographic optical elements (HOEs) of space-variant impulse response have been designed and generated using a computerized optical system. HOEs made of dichromated gelatin have been produced and used for spatial light modulator defect removal and optical interconnects. Experimental performance and characteristics are presented.

A Process Dynamics and Control Experiment for the Undergraduate Laboratory

ERIC Educational Resources Information Center

Spencer, Jordan L.

2009-01-01

This paper describes a process control experiment. The apparatus includes a three-vessel glass flow system with a variable flow configuration, means for feeding dye solution controlled by a stepper-motor driven valve, and a flow spectrophotometer. Students use impulse response data and nonlinear regression to estimate three parameters of a model…

Efficient FIR Filter Implementations for Multichannel BCIs Using Xilinx System Generator.

PubMed

Ghani, Usman; Wasim, Muhammad; Khan, Umar Shahbaz; Mubasher Saleem, Muhammad; Hassan, Ali; Rashid, Nasir; Islam Tiwana, Mohsin; Hamza, Amir; Kashif, Amir

2018-01-01

Background . Brain computer interface (BCI) is a combination of software and hardware communication protocols that allow brain to control external devices. Main purpose of BCI controlled external devices is to provide communication medium for disabled persons. Now these devices are considered as a new way to rehabilitate patients with impunities. There are certain potentials present in electroencephalogram (EEG) that correspond to specific event. Main issue is to detect such event related potentials online in such a low signal to noise ratio (SNR). In this paper we propose a method that will facilitate the concept of online processing by providing an efficient filtering implementation in a hardware friendly environment by switching to finite impulse response (FIR). Main focus of this research is to minimize latency and computational delay of preprocessing related to any BCI application. Four different finite impulse response (FIR) implementations along with large Laplacian filter are implemented in Xilinx System Generator. Efficiency of 25% is achieved in terms of reduced number of coefficients and multiplications which in turn reduce computational delays accordingly.

Fixed-time stabilization of impulsive Cohen-Grossberg BAM neural networks.

PubMed

Li, Hongfei; Li, Chuandong; Huang, Tingwen; Zhang, Wanli

2018-02-01

This article is concerned with the fixed-time stabilization for impulsive Cohen-Grossberg BAM neural networks via two different controllers. By using a novel constructive approach based on some comparison techniques for differential inequalities, an improvement theorem of fixed-time stability for impulsive dynamical systems is established. In addition, based on the fixed-time stability theorem of impulsive dynamical systems, two different control protocols are designed to ensure the fixed-time stabilization of impulsive Cohen-Grossberg BAM neural networks, which include and extend the earlier works. Finally, two simulations examples are provided to illustrate the validity of the proposed theoretical results. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparison of Respiratory Resistance Measurements Made with an Airflow Perturbation Device with Those from Impulse Oscillometry

PubMed Central

Pan, J.; Saltos, A.; Smith, D.; Johnson, A.; Vossoughi, J.

2013-01-01

The airflow perturbation device (APD) has been developed as a portable, easy to use, and a rapid response instrument for measuring respiratory resistance in humans. However, the APD has limited data validating it against the established techniques. This study used a mechanical system to simulate the normal range of human breathing to validate the APD with the clinically accepted impulse oscillometry (IOS) technique. The validation system consisted of a sinusoidal flow generator with ten standardized resistance configurations that were shown to represent a total range of resistances from 0.12 to 0.95 kPa·L−1 ·s (1.2–9.7 cm H2O·L−1 ·s). Impulse oscillometry measurements and APD measurements of the mechanical system were recorded and compared at a constant airflow of 0.15 L·s−1. Both the IOS and APD measurments were accurate in assessing nominal resistance. In addition, a strong linear relationship was observed between APD measurements and IOS measurements (R 2 = 0.999). A second series of measurements was made on ten human volunteers with external resistors added in their respiratory flow paths. Once calibrated with the mechanical system, the APD gave respiratory resistance measurements within 5% of IOS measurements. Because of their comparability to IOS measurements, APD measurements are shown to be valid representations of respiratory resistance. PMID:27006908

High-Q microwave photonic filter with a tuned modulator.

PubMed

Capmany, J; Mora, J; Ortega, B; Pastor, D

2005-09-01

We propose the use of tuned electro-optic or electroabsorption external modulators to implement high-quality (high-Q) factor, single-bandpass photonic filters for microwave signals. Using this approach, we experimentally demonstrate a transversal finite impulse response with a Q factor of 237. This is to our knowledge the highest value ever reported for a passive finite impulse-response microwave photonic filter.

A Fresh Look at Linear Ordinary Differential Equations with Constant Coefficients. Revisiting the Impulsive Response Method Using Factorization

ERIC Educational Resources Information Center

Camporesi, Roberto

2016-01-01

We present an approach to the impulsive response method for solving linear constant-coefficient ordinary differential equations of any order based on the factorization of the differential operator. The approach is elementary, we only assume a basic knowledge of calculus and linear algebra. In particular, we avoid the use of distribution theory, as…

Eyes Wide Shopped: Shopping Situations Trigger Arousal in Impulsive Buyers

PubMed Central

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

2014-01-01

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

A Finite-Element Method Model of Soft Tissue Response to Impulsive Acoustic Radiation Force

PubMed Central

Palmeri, Mark L.; Sharma, Amy C.; Bouchard, Richard R.; Nightingale, Roger W.; Nightingale, Kathryn R

2010-01-01

Several groups are studying acoustic radiation force and its ability to image the mechanical properties of tissue. Acoustic radiation force impulse (ARFI) imaging is one modality using standard diagnostic ultrasound scanners to generate localized, impulsive, acoustic radiation forces in tissue. The dynamic response of tissue is measured via conventional ultrasonic speckle-tracking methods and provides information about the mechanical properties of tissue. A finite-element method (FEM) model has been developed that simulates the dynamic response of tissues, with and without spherical inclusions, to an impulsive acoustic radiation force excitation from a linear array transducer. These FEM models were validated with calibrated phantoms. Shear wave speed, and therefore elasticity, dictates tissue relaxation following ARFI excitation, but Poisson’s ratio and density do not significantly alter tissue relaxation rates. Increased acoustic attenuation in tissue increases the relative amount of tissue displacement in the near field compared with the focal depth, but relaxation rates are not altered. Applications of this model include improving image quality, and distilling material and structural information from tissue’s dynamic response to ARFI excitation. Future work on these models includes incorporation of viscous material properties and modeling the ultrasonic tracking of displaced scatterers. PMID:16382621

A model-independent comparison of the rates of uptake and short term retention of 47Ca and 85Sr by the skeleton.

PubMed

Reeve, J; Hesp, R

1976-12-22

1. A method has been devised for comparing the impulse response functions of the skeleton for two or more boneseeking tracers, and for estimating the contribution made by measurement errors to the differences between any pair of impulse response functions. 2. Comparisons were made between the calculated impulse response functions for 47Ca and 85Sr obtained in simultaneous double tracer studies in sixteen subjects. Collectively the differences between the 47Ca and 85Sr functions could be accounted for entirely by measurement errors. 3. Because the calculation of an impulse response function requires fewer a priori assumptions than other forms of mathematical analysis, and automatically corrects for differences induced by recycling of tracer and non-identical rates of excretory plasma clearance of tracer, it is concluded that differences shown in previous in vivo studies between the fluxes of Ca and Sr into bone can be fully accounted for by undetermined oversimplifications in the various mathematical models used to analyse the results of those studies. 85Sr is therefore an adequate tracer for bone calcium in most in vivo studies.

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

Merkel cells transduce and encode tactile stimuli to drive Aβ-afferent impulses

PubMed Central

Ikeda, Ryo; Cha, Myeounghoon; Ling, Jennifer; Jia, Zhanfeng; Coyle, Dennis; Gu, Jianguo G.

2014-01-01

SUMMARY Sensory systems for detecting tactile stimuli have evolved from touch-sensing nerves in invertebrates to complicated tactile end-organs in mammals. Merkel discs are tactile end-organs consisting of Merkel cells and Aβ-afferent nerve endings, and are localized in fingertips, whisker hair follicles and other touch-sensitive spots. Merkel discs transduce touch into slowly adapting impulses to enable tactile discrimination, but their transduction and encoding mechanisms remain unknown. Using rat whisker hair follicles, we show that Merkel cells rather than Aβ-afferent nerve endings are primary sites of tactile transduction, and identify the Piezo2 ion channel as the Merkel cell mechanical transducer. Piezo2 transduces tactile stimuli into Ca2+-action potentials in Merkel cells, which drive Aβ-afferent nerve endings to fire slowly adapting impulses. We further demonstrate that Piezo2 and Ca2+-action potentials in Merkel cells are required for behavioral tactile responses. Our findings provide insights into how tactile end-organs function and have clinical implications for tactile dysfunctions. PMID:24746027

Calculation of zero-offset vertical seismic profiles generated by a horizontal point force acting on the surface of an elastic half-space

USGS Publications Warehouse

Hsi-Ping, Liu

1990-01-01

Impulse responses including near-field terms have been obtained in closed form for the zero-offset vertical seismic profiles generated by a horizontal point force acting on the surface of an elastic half-space. The method is based on the correspondence principle. Through transformation of variables, the Fourier transform of the elastic impulse response is put in a form such that the Fourier transform of the corresponding anelastic impulse response can be expressed as elementary functions and their definite integrals involving distance angular frequency, phase velocities, and attenuation factors. These results are used for accurate calculation of shear-wave arrival rise times of synthetic seismograms needed for data interpretation of anelastic-attenuation measurements in near-surface sediment. -Author

Impulse response measurement in the HgCdTe avalanche photodiode

NASA Astrophysics Data System (ADS)

Singh, Anand; Pal, Ravinder

2018-04-01

HgCdTe based mid-wave infrared focal plane arrays (MWIR FPAs) are being developed for high resolution imaging and range determination of distant camouflaged targets. Effect of bandgap grading on the response time in the n+/ν/p+ HgCdTe electron avalanche photodiode (e-APD) is evaluated using impulse response measurement. Gain normalized dark current density of 2 × 10-9 A/cm2 at low reverse bias for passive mode and 2 × 10-4 A/cm2 at -8 V for active mode is measured in the fabricated APD device, yielding high gain bandwidth product of 2.4 THZ at the maximum gain. Diffusion of carriers is minimized to achieve transit time limited impulse response by introducing composition grading in the HgCdTe epilayer. The noise equivalent photon performance less than one is achievable in the FPA that is suitable for active cum passive imaging applications.

Delay discounting and response disinhibition under acute experimental stress in women with borderline personality disorder and adult attention deficit hyperactivity disorder.

PubMed

Krause-Utz, A; Cackowski, S; Daffner, S; Sobanski, Esther; Plichta, Michael M; Bohus, M; Ende, G; Schmahl, C

2016-11-01

Impulsivity is a core feature of borderline personality disorder (BPD) and attention deficit hyperactivity disorder (ADHD). In BPD, impulsive behavior primarily occurs under acute stress; impulse control deficits under non-stress conditions may be partly related to co-morbid ADHD. We aimed to investigate whether acute experimental stress has an impact on self-reported impulsivity, response inhibition (action withholding, action cancelation) and delay discounting in BPD compared to ADHD. Thirty female BPD patients, 28 female ADHD patients (excluding patients with co-morbid BPD and ADHD), and 30 female healthy controls (HC) completed self-reports and behavioral measures of impulsivity (IMT, assessing action withholding; GoStop, measuring action cancelation, Delay Discounting Task) under baseline conditions and after an experimental stress induction (Mannheim Multicomponent Stress Test). Both patient groups reported higher impulsivity than HC, ADHD reported higher trait impulsivity than BPD. On the IMT, ADHD showed significant action-withholding deficits under both conditions, while BPD performed significantly worse than HC under stress. In BPD but not ADHD and HC, action-withholding deficits (IMT) were significantly increased under stress compared to baseline, while no group/stress effects were found for action cancelation (GoStop). Delay discounting was significantly more pronounced in BPD than in HC (no stress effect was found). In BPD, behavioral deficits in action withholding (but not in action cancelation) appear to be influenced by acute experimental stress. Delay discounting seems to be a general feature of BPD, independent of co-morbid ADHD and acute stress, possibly underlying typical expressions of behavioral impulsivity in the disorder.

Image Processing for Cameras with Fiber Bundle Image Relay

DTIC Science & Technology

length. Optical fiber bundles have been used to couple between this focal surface and planar image sensors . However, such fiber-coupled imaging systems...coupled to six discrete CMOS focal planes. We characterize the locally space-variant system impulse response at various stages: monocentric lens image...vignetting, and stitch together the image data from discrete sensors into a single panorama. We compare processed images from the prototype to those taken with

Recent Applications of the Volterra Theory to Aeroelastic Phenomena

NASA Technical Reports Server (NTRS)

Silva, Walter A.; Haji, Muhammad R; Prazenica, Richard J.

2005-01-01

The identification of nonlinear aeroelastic systems based on the Volterra theory of nonlinear systems is presented. Recent applications of the theory to problems in experimental aeroelasticity are reviewed. These results include the identification of aerodynamic impulse responses, the application of higher-order spectra (HOS) to wind-tunnel flutter data, and the identification of nonlinear aeroelastic phenomena from flight flutter test data of the Active Aeroelastic Wing (AAW) aircraft.

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

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.

The Minimum Impulse Thruster

NASA Technical Reports Server (NTRS)

Parker, J. Morgan; Wilson, Michael J.

2005-01-01

The Minimum Impulse Thruster (MIT) was developed to improve the state-of-the-art minimum impulse capability of hydrazine monopropellant thrusters. Specifically, a new fast response solenoid valve was developed, capable of responding to a much shorter electrical pulse width, thereby reducing the propellant flow time and the minimum impulse bit. The new valve was combined with the Aerojet MR-103, 0.2 lbf (0.9 N) thruster and put through an extensive Delta-qualification test program, resulting in a factor of 5 reduction in the minimum impulse bit, from roughly 1.1 milli-lbf-seconds (5 milliNewton seconds) to - 0.22 milli-lbf-seconds (1 mN-s). To maintain it's extensive heritage, the thruster itself was left unchanged. The Minimum Impulse Thruster provides mission and spacecraft designers new design options for precision pointing and precision translation of spacecraft.

Annual Review of Research Under the Joint Services Electronics Program.

DTIC Science & Technology

1983-12-01

Total Number of Professionals: PI 2 RA 2 (1/2 time ) 6. Sunmmary: Our research into the theory of nonlinear control systems and appli- * cations to...known that all linear time -invariant controllable systems can be transformed to Brunovsky canonical form by a transformation consist- ing only of...estimating the impulse response ( = transfer matrix) of a discrete- time linear system x(t+l) = Fx(t) + Gu(t) y(t) = Hx(t) from a finite set of finite

Multi-disciplinary optimization of aeroservoelastic systems

NASA Technical Reports Server (NTRS)

Karpel, Mardechay

1992-01-01

The purpose of the research project was to continue the development of new methods for efficient aeroservoelastic analysis and optimization. The main targets were as follows: to complete the development of analytical tools for the investigation of flutter with large stiffness changes; to continue the work on efficient continuous gust response and sensitivity derivatives; and to advance the techniques of calculating dynamic loads with control and unsteady aerodynamic effects. An efficient and highly accurate mathematical model for time-domain analysis of flutter during which large structural changes occur was developed in cooperation with Carol D. Wieseman of NASA LaRC. The model was based on the second-year work 'Modal Coordinates for Aeroelastic Analysis with Large Local Structural Variations'. The work on continuous gust response was completed. An abstract of the paper 'Continuous Gust Response and Sensitivity Derivatives Using State-Space Models' was submitted for presentation in the 33rd Israel Annual Conference on Aviation and Astronautics, Feb. 1993. The abstract is given in Appendix A. The work extends the optimization model to deal with continuous gust objectives in a way that facilitates their inclusion in the efficient multi-disciplinary optimization scheme. Currently under development is a work designed to extend the analysis and optimization capabilities to loads and stress considerations. The work is on aircraft dynamic loads in response to impulsive and non-impulsive excitation. The work extends the formulations of the mode-displacement and summation-of-forces methods to include modes with significant local distortions, and load modes. An abstract of the paper,'Structural Dynamic Loads in Response to Impulsive Excitation' is given in appendix B. Another work performed this year under the Grant was 'Size-Reduction Techniques for the Determination of Efficient Aeroservoelastic Models' given in Appendix C.

Do Different Facets of Impulsivity Predict Different Types of Aggression?

PubMed Central

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

2011-01-01

The current study examined the relations between impulsivity-related traits (as assessed by the UPPS-P Impulsive Behavior Scale) and aggressive behaviors. Results indicated that UPPS-P Lack of Premeditation and Sensation Seeking were important in predicting general violence. In contrast, UPPS-P Urgency was most useful in predicting intimate partner violence. To further explore relations between intimate partner violence and Urgency, a measure of autonomic response to pleasant and aversive stimuli and facets of Neuroticism from the NEO PI-R were used as control variables. Autonomic responsivity was correlated with intimate partner violence at the zero-order level, and predicted significant variance in intimate partner violence in regression equations. However, UPPS-P Urgency was able to account for unique variance in intimate partner violence above and beyond measures of Neuroticism and arousal. Implications regarding the use of a multifaceted conceptualization of impulsivity in the prediction of different types of violent behavior are discussed. PMID:21259270

Hybrid rocket propulsion

NASA Technical Reports Server (NTRS)

Holzman, Allen L.

1993-01-01

Topics addressed are: (1) comparison of the theoretical impulses; (2) comparison of the density-specific impulses; (3) general propulsion system features comparison; (4) hybrid systems, booster applications; and (5) hybrid systems, upper stage propulsion applications.

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

Specific Impulse and Mass Flow Rate Error

NASA Technical Reports Server (NTRS)

Gregory, Don A.

2005-01-01

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

Anti-impulse-noise Edge Detection via Anisotropic Morphological Directional Derivatives.

PubMed

Shui, Peng-Lang; Wang, Fu-Ping

2017-07-13

Traditional differential-based edge detection suffers from abrupt degradation in performance when images are corrupted by impulse noises. The morphological operators such as the median filters and weighted median filters possess the intrinsic ability to counteract impulse noise. In this paper, by combining the biwindow configuration with weighted median filters, anisotropic morphological directional derivatives (AMDD) robust to impulse noise are proposed to measure the local grayscale variation around a pixel. For ideal step edges, the AMDD spatial response and directional representation are derived. The characteristics and edge resolution of two kinds of typical biwindows are analyzed thoroughly. In terms of the AMDD spatial response and directional representation of ideal step edges, the spatial matched filter is used to extract the edge strength map (ESM) from the AMDDs of an image. The spatial and directional matched filters are used to extract the edge direction map (EDM). Embedding the extracted ESM and EDM into the standard route of the differential-based edge detection, an anti-impulse-noise AMDD-based edge detector is constructed. It is compared with the existing state-of-the-art detectors on a recognized image dataset for edge detection evaluation. The results show that it attains competitive performance in noise-free and Gaussian noise cases and the best performance in impulse noise cases.

Auditorium acoustics evaluation based on simulated impulse response

NASA Astrophysics Data System (ADS)

Wu, Shuoxian; Wang, Hongwei; Zhao, Yuezhe

2004-05-01

The impulse responses and other acoustical parameters of Huangpu Teenager Palace in Guangzhou were measured. Meanwhile, the acoustical simulation and auralization based on software ODEON were also made. The comparison between the parameters based on computer simulation and measuring is given. This case study shows that auralization technique based on computer simulation can be used for predicting the acoustical quality of a hall at its design stage.

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.

Shock spectra applications to a class of multiple degree-of-freedom structures system

NASA Technical Reports Server (NTRS)

Hwang, Shoi Y.

1988-01-01

The demand on safety performance of launching structure and equipment system from impulsive excitations necessitates a study which predicts the maximum response of the system as well as the maximum stresses in the system. A method to extract higher modes and frequencies for a class of multiple degree-of-freedom (MDOF) Structure system is proposed. And, along with the shock spectra derived from a linear oscillator model, a procedure to obtain upper bound solutions for maximum displacement and maximum stresses in the MDOF system is presented.

Systems for measuring response statistics of gigahertz bandwidth photomultipliers

NASA Technical Reports Server (NTRS)

Abshire, J. B.; Rowe, H. E.

1977-01-01

New systems have been developed for measuring the average impulse response, the pulse-height spectrum, the transit-time statistics as a function of signal level, and the dark-count spectrum of gigahertz bandwidth photomultipliers. Measurements showed that the 0.53 microns pulse used as an optical test source had a 30 picoseconds and less than 70 ps pulse width. Calibration data showed the system resolution to be less than 20 ps for root mean square transit-time measurements. Test data for a static crossed-field photomultiplier showed 2-photoelectron resolution and less than 30-ps time jitter over the 1- to 100-photoelectron range.

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.

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.

Modulation of meso-limbic reward processing by motivational tendencies in young adolescents and adults

PubMed Central

Joseph, Jane E.; Zhu, Xun; Lynam, Donald; Kelly, Thomas H.

2015-01-01

Adolescence is a particularly vulnerable period for the onset of substance use disorders and other psychopathology. Individual variability in motivational tendencies and temperament and significant changes in functional brain organization during adolescence are important factors to consider in the development of substance use and dependence. Recent conceptualizations suggest that sensitivity to reward is heightened in adolescence and that this motivation tendency may precipitate subsequent substance abuse. The present study examined the role of personality traits in mesolimbic neurobehavioral response on a monetary incentive delay (MID) task in young adolescents (11–14 years) and emerging adults (18–25 years) using functional magnetic resonance imaging. As a group, adolescents were not more sensitive to gains than losses compared to adults during either anticipatory and feedback phases; instead, compared to adults they showed less sensitivity to incentive magnitude in mesolimbic circuitry during anticipation and feedback stages. However, personality modulated this response such that adolescents high in impulsivity or low in avoidance tendencies showed greater gain sensitivity and adolescents high in avoidance showed greater loss sensitivity during cue anticipation. In adults, mesolimbic response was modulated by the impulsivity construct such that high-impulsive adults showed reduced magnitude sensitivity during both anticipation and feedback compared to low impulsive adults. The present findings suggest that impulsive personality significantly modulates mesolimbic reward response during both adolescence and adulthood but avoidance and approach tendencies also modulate this response in adolescents. Moreover, personality modulated incentive valence in adolescents but incentive magnitude in adults. Collectively, these findings suggest that mesolimbic reward circuitry function is modulated by somewhat different parameters in adolescence than in adulthood. PMID:26690806

Time history solution program, L225 (TEV126). Volume 1: Engineering and usage

NASA Technical Reports Server (NTRS)

Kroll, R. I.; Tornallyay, A.; Clemmons, R. E.

1979-01-01

Volume 1 of a two volume document is presented. The usage of the convolution program L225 (TEV 126) is described. The program calculates the time response of a linear system by convoluting the impulsive response function with the time-dependent excitation function. The convolution is performed as a multiplication in the frequency domain. Fast Fourier transform techniques are used to transform the product back into the time domain to obtain response time histories. A brief description of the analysis used is presented.

Linking pulses of atmospheric deposition to DOC release in an upland peat-covered catchment

NASA Astrophysics Data System (ADS)

Worrall, F.; Burt, T. P.; Adamson, J. K.

2008-12-01

Changes in atmospheric deposition have been proposed as one possible explanation of the widespread increase in DOC concentration observed in many Northern Hemisphere catchments. This study uses detailed, long-term, monthly monitoring records of pH, conductivity SO4, and DOC in precipitation, soil water, and runoff chemistry from an upland peat-covered catchment in northern England. By deriving impulse transfer functions this study explores whether changes in deposition lead to significant changes in the occurrence of each component in the soil and runoff water; especially significant changes in DOC. The study shows that (1) impulses in the deposition of acidity have no significant effect upon pH or DOC in soil water or runoff. (2) DOC in soil water and runoff is responsive to impulses in SO4 and conductivity, but only when those impulses are changes in soil water chemistry and not when they are in atmospheric deposition. (3) The effects of changes in SO4 and/or conductivity can easily be overemphasized if memory effects are not accounted for, and their effect is limited to only 1 or 2 months after a severe drought. This study can support the view that changes in ionic strength can result in changes in DOC concentration in soil water or runoff, but the system studied is unresponsive to changes in atmospheric deposition. Impulses in soil water SO4 do not lead to increases in DOC concentrations, and so this mechanism does not provide an explanation for DOC increases.

Overlapping Neural Endophenotypes in Addiction and Obesity

PubMed Central

Michaud, Andréanne; Vainik, Uku; Garcia-Garcia, Isabel; Dagher, Alain

2017-01-01

Impulsivity refers to a tendency to act rapidly without full consideration of consequences. The trait is thought to result from the interaction between high arousal responses to potential rewards and poor self-control. Studies have suggested that impulsivity confers vulnerability to both addiction and obesity. However, results in this area are unclear, perhaps due to the high phenotypic complexity of addictions and obesity. Focusing on impulsivity, the aim of this review is to tackle the putative overlaps between addiction and obesity in four domains: (1) personality research, (2) neurocognitive tasks, (3) brain imaging, and (4) clinical evidence. We suggest that three impulsivity-related domains are particularly relevant for our understanding of similarities between addiction and obesity: lower self-control (high Disinhibition/low Conscientiousness), reward sensitivity (high Extraversion/Positive Emotionality), and negative affect (high Neuroticism/Negative Emotionality). Neurocognitive studies have shown that obesity and addiction are both associated with increased impulsive decision-making and attention bias in response to drug or food cues, respectively. Mirroring this, obesity and different forms of addiction seem to exhibit similar alterations in functional MRI brain activity in response to reward processing and during self-control tasks. Overall, our review provides an integrative approach to understand those facets of obesity that present similarities to addictive behaviors. In addition, we suggest that therapeutic interventions targeting inhibitory control may represent a promising approach for the prevention and/or treatment of obesity. PMID:28659866

An investigation of two dimensions of impulsivity as predictors of loss-of-control eating severity and frequency.

PubMed

Espel, Hallie M; Muratore, Alexandra F; Lowe, Michael R

2017-10-01

Loss-of-control (LOC) eating episodes represent one form of dysregulated eating common to full- and sub-threshold eating disorders. Extensive evidence suggests that impulsivity, particularly in the context of negative affect and/or depression, may play an important etiological role in the development and maintenance of LOC eating. However, most prior studies have considered LOC eating as a dichotomous rather than dimensional construct, and few studies have considered the interaction of multiple dimensions of impulsivity while also accounting for the role of depressive symptoms. The present study examined the independent and interacting effects of two facets of impulsivity-response inhibition and negative urgency-on LOC eating episode severity and frequency among college women (N = 102). Depressive symptom severity was included as a covariate. Results indicated that greater negative urgency was associated with greater LOC severity; this effect was moderated by response inhibition, such that the effect of urgency was particularly pronounced for individuals with higher response inhibition capacity. Negative urgency was the only significant predictor of LOC frequency. Depression had no significant effect on either LOC severity or frequency (ps ≥ 0.16). Results support the importance of considering multiple facets of impulsivity in predicting LOC eating behavior, and further indicate that factors influencing subjective severity and frequency of LOC may be distinct. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effects of physical activity on impulsive choice: Influence of sensitivity to reinforcement amount and delay.

PubMed

Strickland, Justin C; Feinstein, Max A; Lacy, Ryan T; Smith, Mark A

2016-05-01

Impulsive choice is a diagnostic feature and/or complicating factor for several psychological disorders and may be examined in the laboratory using delay-discounting procedures. Recent investigators have proposed using quantitative measures of analysis to examine the behavioral processes contributing to impulsive choice. The purpose of this study was to examine the effects of physical activity (i.e., wheel running) on impulsive choice in a single-response, discrete-trial procedure using two quantitative methods of analysis. To this end, rats were assigned to physical activity or sedentary groups and trained to respond in a delay-discounting procedure. In this procedure, one lever always produced one food pellet immediately, whereas a second lever produced three food pellets after a 0, 10, 20, 40, or 80-s delay. Estimates of sensitivity to reinforcement amount and sensitivity to reinforcement delay were determined using (1) a simple linear analysis and (2) an analysis of logarithmically transformed response ratios. Both analyses revealed that physical activity decreased sensitivity to reinforcement amount and sensitivity to reinforcement delay. These findings indicate that (1) physical activity has significant but functionally opposing effects on the behavioral processes that contribute to impulsive choice and (2) both quantitative methods of analysis are appropriate for use in single-response, discrete-trial procedures. Copyright © 2016 Elsevier B.V. All rights reserved.

Systemic administration of guanfacine improves food-motivated impulsive choice behavior primarily via direct stimulation of postsynaptic α2A-adrenergic receptors in rats.

PubMed

Nishitomi, Kouhei; Yano, Koji; Kobayashi, Mika; Jino, Kohei; Kano, Takuya; Horiguchi, Naotaka; Shinohara, Shunji; Hasegawa, Minoru

2018-06-01

Impulsive choice behavior, which can be assessed using the delay discounting task, is a characteristic of various psychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD). Guanfacine is a selective α 2A -adrenergic receptor agonist that is clinically effective in treating ADHD. However, there is no clear evidence that systemic guanfacine administration reduces impulsive choice behavior in the delay discounting task in rats. In the present study, we examined the effect of systemic guanfacine administration on food-motivated impulsive choice behavior in rats and the neuronal mechanism underlying this effect. Repeated administration of either guanfacine, methylphenidate, or atomoxetine significantly enhanced impulse control, increasing the number of times the rats chose a large but delayed reward in a dose-dependent manner. The effect of guanfacine was significantly blocked by pretreatment with an α 2A -adrenergic receptor antagonist. Furthermore, the effect of guanfacine remained unaffected in rats pretreated with a selective noradrenergic neurotoxin, consistent with a post-synaptic action. In contrast, the effect of atomoxetine on impulsive choice behavior was attenuated by pretreatment with the noradrenergic neurotoxin. These results provide the first evidence that systemically administered guanfacine reduces impulsive choice behavior in rats and that direct stimulation of postsynaptic, rather than presynaptic, α 2A -adrenergic receptors is involved in this effect. Copyright © 2018 Elsevier B.V. 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.

Significance of a Recurring Function in Energy Transfer

NASA Astrophysics Data System (ADS)

Mishra, Subodha

2017-05-01

The appearance of a unique function in the energy transfer from one system to the other in different physical situations such as electrical, mechanical, optical, and quantum mechanical processes is established in this work. Though the laws governing the energy transformation and its transfer from system to system are well known, here we notice a unity in diversity; a unique function appears in various cases of energy transfer whether it is a classical or a quantum mechanical process. We consider four examples, well known in elementary physics, from the fields of electricity, mechanics, optics, and quantum mechanics. We find that this unique function is in fact the transfer function corresponding to all these physical situations, and the interesting and intriguing finding is that the inverse Laplace transform of this transfer function, which is the impulse-response function of the systems when multiplied by a factor of -½, is the solution of a linear differential equation for an "instantly forced critically damped harmonic oscillator." It is important to note that though the physical phenomena considered are quite distinct, the underlying process in the language of impulse-response of the system in the time domain is a unique one. To the best of our knowledge we have not seen anywhere the above analysis of determining the unique function or its description as a transfer function in literature.

Validity of DSM-IV attention–deficit/hyperactivity disorder symptom dimensions and subtypes

PubMed Central

Willcutt, Erik G.; Nigg, Joel T.; Pennington, Bruce F.; Solanto, Mary V.; Rohde, Luis A.; Tannock, Rosemary; Loo, Sandra K.; Carlson, Caryn L.; McBurnett, Keith; Lahey, Benjamin B.

2013-01-01

DSM-IV criteria for ADHD specify two dimensions of inattention and hyperactivity-impulsivity symptoms that are used to define three nominal subtypes: predominantly hyperactive-impulsive type (ADHD-H), predominantly inattentive type (ADHD-I), and combined type (ADHD-C). To aid decision-making for DSM-5 and other future diagnostic systems, a comprehensive literature review and meta-analysis of 546 studies was completed to evaluate the validity of the DSM-IV model of ADHD. Results indicated that DSM-IV criteria identify individuals with significant and persistent impairment in social, academic, occupational, and adaptive functioning when intelligence, demographic factors, and concurrent psychopathology are controlled. Available data overwhelmingly support the concurrent, predictive, and discriminant validity of the distinction between inattention and hyperactivity-impulsivity symptoms, and indicate that nearly all differences among the nominal subtypes are consistent with the relative levels of inattention and hyperactivity-impulsivity symptoms that define the subtypes. In contrast, the validity of the DSM-IV subtype model is compromised by weak evidence for the validity of ADHD-H after first grade, minimal support for the distinction between ADHD-I and ADHD-C in studies of etiological influences, academic and cognitive functioning, and treatment response, and the marked longitudinal instability of all three subtypes. Overall, it is concluded that the DSM-IV ADHD subtypes provide a convenient clinical shorthand to describe the functional and behavioral correlates of current levels of inattention and hyperactivity-impulsivity symptoms, but do not identify discrete subgroups with sufficient long-term stability to justify the classification of distinct forms of the disorder. Empirical support is stronger for an alternative model that would replace the subtypes with dimensional modifiers that reflect the number of inattention and hyperactivity-impulsivity symptoms at the time of assessment. PMID:22612200

Comparison of methods of predicting community response to impulsive and nonimpulsive noise

NASA Technical Reports Server (NTRS)

Fidell, Sanford; Pearsons, Karl S.

1994-01-01

Several scientific, regulatory, and policy-coordinating bodies have developed methods for predicting community response to sonic booms. The best known of these is the dosage-response relationship of Working Group 84 of the National Academy of Science's Committee on Hearing, Bioacoustics and Biomechanics. This dosage-response relationship between C-weighted DayNight Average Sound Level and the prevalence of annoyance with high energy impulsive sounds was derived from limited amounts of information about community response to regular, prolonged, and expected exposure to artillery and sonic booms. U.S. Army Regulation 201 adapts this approach to predictions of the acceptability of impulsive noise exposure in communities. This regulation infers equivalent degrees of effect with respect to a well known dosage-response relationship for general (nonimpulsive) transportation noise. Differences in prevalence of annoyance predicted by various relationships lead to different predictions of the compatibility of land uses with sonic boom exposure. An examination of these differences makes apparent several unresolved issues in current practice for predicting and interpreting the prevalence of annoyance due to sonic boom exposure.

Influence of temperature conditions in outer space on the macrokinetic characteristics of ignition and combustion of the solid-fuel charge of the microthruster of a microelectromechanical system

NASA Astrophysics Data System (ADS)

Futko, S. I.; Bondarenko, V. P.; Dolgii, L. N.

2012-03-01

On the basis of macrokinetic calculations, the influence of the initial temperature on the impulse responses of the processes of ignition and combustion of the solid-fuel charge of the microelectromechanical system (MEMS) microthruster burning the solid fuel glycidyl azide polymer (GAP)/RDX has been investigated. It has been established that fuel heating/cooling in a wide range of temperature values from 150 to 450 K characteristic of the conditions of a satellite in orbital flight markedly affects both the thrust and the total impulse of the MEMS microthruster. In so doing, an increase in the initial temperature leads to a marked decrease in the induction period and an increase in the critical flux of fuel ignition. The influence of the change in the initial temperature on the self-ignition temperature of GAP can be neglected. To obtain stable characteristics of the microthruster, it seems expedient to use a thermostating system.

The impact of comorbid impulsive/compulsive disorders in problematic Internet use.

PubMed

Chamberlain, Samuel R; Ioannidis, Konstantinos; Grant, Jon E

2018-05-23

Background and aims Problematic Internet use (PIU) is commonplace but is not yet recognized as a formal mental disorder. Excessive Internet use could result from other conditions such as gambling disorder. The aim of the study was to assess the impact of impulsive-compulsive comorbidities on the presentation of PIU, defined using Young's Diagnostic Questionnaire. Methods A total of 123 adults aged 18-29 years were recruited using media advertisements, and attended the research center for a detailed psychiatric assessment, including interviews, completion of questionnaires, and neuropsychological testing. Participants were classified into three groups: PIU with no comorbid impulsive/compulsive disorders (n = 18), PIU with one or more comorbid impulsive/compulsive disorders (n = 37), and healthy controls who did not have any mental health diagnoses (n = 67). Differences between the three groups were characterized in terms of demographic, clinical, and cognitive variables. Effect sizes for overall effects of group were also reported. Results The three groups did not significantly differ on age, gender, levels of education, nicotine consumption, or alcohol use (small effect sizes). Quality of life was significantly impaired in PIU irrespective of whether or not individuals had comorbid impulsive/compulsive disorders (large effect size). However, impaired response inhibition and decision-making were only identified in PIU with impulsive/compulsive comorbidities (medium effect sizes). Discussion and conclusions Most people with PIU will have one or more other impulsive/compulsive disorders, but PIU can occur without such comorbidities and still present with impaired quality of life. Response inhibition and decision-making appear to be disproportionately impacted in the case of PIU comorbid with other impulsive/compulsive conditions, which may account for some of the inconsistencies in the existing literature. Large scale international collaborations are required to validate PIU and further assess its clinical, cognitive, and biological sequelae.

Coordination of fractional-order nonlinear multi-agent systems via distributed impulsive control

NASA Astrophysics Data System (ADS)

Ma, Tiedong; Li, Teng; Cui, Bing

2018-01-01

The coordination of fractional-order nonlinear multi-agent systems via distributed impulsive control method is studied in this paper. Based on the theory of impulsive differential equations, algebraic graph theory, Lyapunov stability theory and Mittag-Leffler function, two novel sufficient conditions for achieving the cooperative control of a class of fractional-order nonlinear multi-agent systems are derived. Finally, two numerical simulations are verified to illustrate the effectiveness and feasibility of the proposed method.

From Serpent to CEO: Improving First-Term Security Forces Airman Performance Through Neuroscience Education

DTIC Science & Technology

2017-06-09

full ability to inhibit ANS and limbic response are prone to be impulsive, 25 unintentional, or hesitant when faced with high -threat decisions...graduate degrees in Criminal Justice, a Graduate Certificate in Organizational Leadership, and a current American Society for Industrial Security...experience and full ability to inhibit ANS and limbic response are prone to be impulsive, unintentional, or hesitant when faced with high -threat

Input-output characterization of an ultrasonic testing system by digital signal analysis

NASA Technical Reports Server (NTRS)

Karaguelle, H.; Lee, S. S.; Williams, J., Jr.

1984-01-01

The input/output characteristics of an ultrasonic testing system used for stress wave factor measurements were studied. The fundamentals of digital signal processing are summarized. The inputs and outputs are digitized and processed in a microcomputer using digital signal processing techniques. The entire ultrasonic test system, including transducers and all electronic components, is modeled as a discrete-time linear shift-invariant system. Then the impulse response and frequency response of the continuous time ultrasonic test system are estimated by interpolating the defining points in the unit sample response and frequency response of the discrete time system. It is found that the ultrasonic test system behaves as a linear phase bandpass filter. Good results were obtained for rectangular pulse inputs of various amplitudes and durations and for tone burst inputs whose center frequencies are within the passband of the test system and for single cycle inputs of various amplitudes. The input/output limits on the linearity of the system are determined.

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

Egalisation adaptative et non invasive de la reponse temps-frequence d'une petite salle

NASA Astrophysics Data System (ADS)

Martin, Tristan

In this research, we are interested in sound, environment wherein it propagates, the interaction between the sound wave and a transmission channel, and the changes induced by the components of an audio chain. The specific context studied is that of listening to music on loudspeakers. For the environment in which sound wave propagates, like for any transmission channel, there are mathematical functions used to characterize the changes induced by a channel on the signal therethrough. An electric signal serves as a input for a system, in this case consisting of an amplifier, a loudspeaker, and the room where the listening takes place, which according to its characteristics, returns as an output at the listening position, an altered sound wave. Frequency response, impulse response, transfer function, the mathematics used are no different from those used commonly for the characterization of a transmission channel or the expression of the outputs of a linear system to its inputs. Naturally, there is a purpose to this modeling exercise: getting the frequency response of the amplifier/loundspeaker/room chain makes possible its equalization. It is common in many contexts of listening to find a filter inserted into the audio chain between the source (Eg CD player) and the amplifier/loudspeaker that converts the electrical signal to an acoustic signal propagated in the room. This filter, called "equalizer" is intended to compensate the frequency effect of the components of the audio chain and the room on the sound signal that will be transmitted. Properties for designing this filter are derived from those of the audio chain. Although analytically rigorous, physical approach, focusing on physical modeling of the loudspeaker and the propagation equation of the acoustic wave is ill-suited to rooms with complex geometry and changing over time. The second approach, experimental modeling, and therefore that addressed in this work, ignores physical properties. The system audio chain is rather seen as a "black box" including inputs and outputs. The problem studied is the characterization of an electro-acoustic system as having a single input signal transmitted through a speaker in a room, and a single output signal picked up by a microphone at the listening position. The originality of this work lies not only in the technique developed to arrive at this characterization, but especially in the constraints imposed in order to get there. The majority of technics documented to this date involve using excitation signals dedicated the measure; signals with favorable characteristics to simplify the calculation of the impulse response of the audio chain. Known signals are played through a loudspeaker and the room's response to excitation is captured with a microphone at the listening position. The measurement exercise itself poses problem, especially when there is an audience in the room. Also, the response of the room may change between the time of the measurement and time of listening. If the room is reconfigured for example, a curtain is pulled or the stage moved. In the case of a theater, the speaker used may vary depending on the context. A survey of work in which solutions to this problem are suggested was made. The main objective is to develop an innovative method to capture the impulse response of an audio chain without the knowledge of the audience. To do this, no signal dedicated to the measurement should be used. The developed method allows the capture of the electro-acoustic impulse response exploiting only the music signals when it comes to a concert hall or using a movie sound track when a movie is a movie theater. As a result, an algorithm for modeling dynamicly and continuously the response of a room. A finite impulse response filter acting as a digital equalizer must be designed and also able to dynamically adapt the behavior of the room, even when it varies over time. A multi spectral resolution method is used to build, for diffrent frequency bands, the filter response arising from the inversion of the room/speaker frequency response. The resulting dynamically adapting filter has properties similar to those of the human ear, a significant spectral-resolution in lower frequencies, and high time-resolution at high frequencies. The response corrected by the filter system tends approaching to a pure pulse. Techniques explored in the context of this research led to the publication of a scientific article in a peer reviewed journal and one conference paper in which similar methods were used for mining engineering applications. (Abstract shortened by UMI.).

Response of a piezoelectric pressure transducer to IR laser beam impingement

NASA Technical Reports Server (NTRS)

Smith, William C.; Leiweke, Robert J.; Beeson, Harold

1992-01-01

The non-pressure response of a PCB Model 113A transducer to a far infrared radiation impulse from a carbon dioxide laser was investigated. Incident radiation was applied both to the bare transducer diaphragm and to coated diaphragms. Coatings included two common ablative materials and a reflective gold coating. High-flux radiation impulses induced an immediate brief negative output followed by a longer-duration positive output. Both timing and amplitude of the responses will be discussed, and the effects of coatings will be compared. Bursts of blackbody radiation from a 1500 K source produced qualitatively similar responses.

Structural frequency functions for an impulsive, distributed forcing function

NASA Technical Reports Server (NTRS)

Bateman, Vesta I.

1987-01-01

The response of a penetrator structure to a spatially distributed mechanical impulse with a magnitude approaching field test force levels (1-2 Mlb) were measured. The frequency response function calculated from the response to this unique forcing function is compared to frequency response functions calculated from response to point forces of about 2000 pounds. The results show that the strain gages installed on the penetrator case respond similiarly to a point, axial force and to a spatially distributed, axial force. This result suggests that the distributed axial force generated in a penetration event may be reconstructed as a point axial force when the penetrator behaves in linear manner.

Obtaining high-energy responses of nonlinear piezoelectric energy harvester by voltage impulse perturbations

NASA Astrophysics Data System (ADS)

Lan, Chunbo; Tang, Lihua; Qin, Weiyang

2017-07-01

Nonlinear energy harvesters have attracted wide research attentions to achieve broadband performances in recent years. Nonlinear structures have multiple solutions in certain frequency region that contains high-energy and low-energy orbits. It is effectively the frequency region of capturing a high-energy orbit that determines the broadband performance. Thus, maintaining large-amplitude high-energy-orbit oscillations is highly desired. In this paper, a voltage impulse perturbation approach based on negative resistance is applied to trigger high-energy-orbit responses of piezoelectric nonlinear energy harvesters. First, the mechanism of the voltage impulse perturbation and the implementation of the synthetic negative resistance circuit are discussed in detail. Subsequently, numerical simulation and experiment are conducted and the results demonstrate that the high-energy-orbit oscillations can be triggered by the voltage impulse perturbation method for both monostable and bistable configurations given various scenarios. It is revealed that the perturbation levels required to trigger and maintain high-energy-orbit oscillations are different for various excitation frequencies in the region where multiple solutions exist. The higher gain in voltage output when high-energy-orbit oscillations are captured is accompanied with the demand of a higher voltage impulse perturbation level.

Persistent effects of chronic Δ9-THC exposure on motor impulsivity in rats.

PubMed

Irimia, Cristina; Polis, Ilham Y; Stouffer, David; Parsons, Loren H

2015-08-01

In humans, long-term marijuana use is associated with impaired impulse control and attentional capacity, though it has been difficult to distinguish pre-existing cognitive deficits from possible consequences of prolonged marijuana exposure. To evaluate the effects of long-term exposure to Δ9-Tetrahydrocannabinol (Δ9-THC), the primary psychoactive constituent in marijuana, on indices of impulse control and attentional capacity using the rat 5-Choice Serial Reaction Time Task (5-CSRTT). Ten 14-day cycles of Δ9-THC dosing and 5-CSRTT testing were employed, each comprised of 5-day Δ9-THC dosing (0.3 or 3 mg/kg b.i.d.) and 5-CSRTT testing during the 9 days of drug abstinence. Subsequent 5-CSRTT testing continued during 5 weeks of protracted abstinence. Dose-dependent increases in motor impulsivity (premature responses) and behavioral disinhibition (perseverative responses) emerged following 5 cycles of Δ9-THC exposure that persisted for the remaining dosing and testing cycles. Δ9-THC-related disruptions in motor impulsivity and behavioral inhibition were most pronounced during cognitively challenging 5-CSRTT sessions incorporating varying novel inter-trial intervals (ITIs), and these disruptions persisted for at least 5 weeks of Δ9-THC abstinence. Δ9-THC-related impairments in attentional capacity (response accuracy) were also evident during variable ITI challenge tests, though these attentional disruptions abated within 3 weeks of Δ9-THC abstinence. These observations demonstrate that long-term intermittent exposure to clinically meaningful Δ9-THC doses induces persistent impairments in impulse control and attentional function. If present in humans, these disruptions may impact academic and professional performance.

Characterizing Impulsivity in Mania

PubMed Central

Strakowski, Stephen M.; Fleck, David E.; DelBello, Melissa P.; Adler, Caleb M.; Shear, Paula K.; McElroy, Susan L.; Keck, Paul E.; Moss, Quinton; Cerullo, Michael A.; Kotwal, Renu; Arndt, Stephan

2008-01-01

Objective To determine whether specific aspects of impulsivity (response disinhibition, inability to delay gratification, inattention) differ between healthy and bipolar manic subjects, and whether these aspects of impulsivity were associated with each other and severity of affective symptoms. Methods Performance of 70 bipolar I manic or mixed patients was compared to that of 34 healthy subjects on three tasks specifically designed to study response inhibition, ability to delay gratification, and attention; namely a stop signal task, a delayed reward task, and a continuous performance task respectively. Correlations among tasks and with symptom ratings were also performed. Results Bipolar subjects demonstrated significant deficits on all three tasks as compared to healthy subjects. Performance on the three tasks was largely independent. Task performance was not significantly associated with the severity of affective symptom ratings. However, measures of response inhibition and attention were sensitive to medication effects. Differences in the delayed reward task were independent of medication effects or symptom ratings. During the delayed reward task, although bipolar patients made their choices more slowly than healthy subjects, they were significantly more likely to choose a smaller, but more quickly obtained reward. Moreover performance on this task was not associated with performance on the other impulsivity measures. Manic patients showed more impulsive responding than mixed patients. Conclusions Bipolar I manic patients demonstrate deficits on tests of various aspects of impulsivity as compared to healthy subjects. Some of these differences between groups may be mediated by medication effects. Findings suggested that inability to delay gratification (i.e., delayed reward task) was not simply a result of the speed of decision making or inattention, but rather that it reflected differences between bipolar and healthy subjects in the valuation of reward relative to delay. PMID:19133965

Pay attention to impulsivity: modelling low attentive and high impulsive subtypes of adult ADHD in the 5-choice continuous performance task (5C-CPT) in female rats.

PubMed

Tomlinson, Anneka; Grayson, Ben; Marsh, Samuel; Harte, Michael K; Barnes, Samuel A; Marshall, Kay M; Neill, Joanna C

2014-08-01

Varying levels of attention and impulsivity deficits are core features of the three subtypes of adult attention deficit-hyperactivity disorder (ADHD). To date, little is known about the neurobiological correlates of these subtypes. Development of a translational animal model is essential to improve our understanding and improve therapeutic strategies. The 5-choice continuous performance task (5C-CPT) in rats can be used to examine different forms of attention and impulsivity. Adult rats were trained to pre-set 5C-CPT criterion and subsequently separated into subgroups according to baseline levels of sustained attention, vigilance, premature responding and response disinhibition in the 5C-CPT. The behavioural subgroups were selected to represent the different subtypes of adult ADHD. Consequently, effects of the clinically used pharmacotherapies (methylphenidate and atomoxetine) were assessed in the different subgroups. Four subgroups were identified: low-attentive (LA), high-attentive (HA), high-impulsive (HI) and low-impulsive (LI). Methylphenidate and atomoxetine produced differential effects in the subgroups. Methylphenidate increased sustained attention and vigilance in LA animals, and reduced premature responding in HI animals. Atomoxetine also improved sustained attention and vigilance in LA animals, and reduced response disinhibition and premature responding in HI animals. This is the first study using adult rats to demonstrate the translational value of the 5C-CPT to select subgroups of rats, which may be used to model the subtypes observed in adult ADHD. Our findings suggest that this as an important paradigm to increase our understanding of the neurobiological underpinnings of adult ADHD-subtypes and their response to pharmacotherapy. Copyright © 2014 Elsevier B.V. and ECNP. All rights reserved.

Vibration transfer mobility measurements using maximum length sequences

NASA Astrophysics Data System (ADS)

Singleton, Herbert L.

2005-09-01

Vibration transfer mobility measurements are required under Federal Transit Administration guidelines when developing detailed predictions of ground-borne vibration for rail transit systems. These measurements typically use a large instrumented hammer to generate impulses in the soil. These impulses are measured by an array of accelerometers to characterize the transfer mobility of the ground in a localized area. While effective, these measurements often make use of heavy, custom-engineered equipment to produce the impulse signal. To obtain satisfactory signal-to-noise ratios, it is necessary to generate multiple impulses to generate an average value, but this process involves considerable physical labor in the field. To address these shortcomings, a transfer mobility measurement system utilizing a tactile transducer and maximum length sequences (MLS) was developed. This system uses lightweight off-the-shelf components to significantly reduce the weight and cost of the system. The use of MLS allows for adequate signal-to-noise ratio from the tactile transducer, while minimizing the length of the measurement. Tests of the MLS system show good agreement with the impulse-based method. The combination of the cost savings and reduced weight of this new system facilitates transfer mobility measurements that are less physically demanding, and more economical when compared with current methods.

Decision making, impulse control and loss of willpower to resist drugs: a neurocognitive perspective.

PubMed

Bechara, Antoine

2005-11-01

Here I argue that addicted people become unable to make drug-use choices on the basis of long-term outcome, and I propose a neural framework that explains this myopia for future consequences. I suggest that addiction is the product of an imbalance between two separate, but interacting, neural systems that control decision making: an impulsive, amygdala system for signaling pain or pleasure of immediate prospects, and a reflective, prefrontal cortex system for signaling pain or pleasure of future prospects. After an individual learns social rules, the reflective system controls the impulsive system via several mechanisms. However, this control is not absolute; hyperactivity within the impulsive system can override the reflective system. I propose that drugs can trigger bottom-up, involuntary signals originating from the amygdala that modulate, bias or even hijack the goal-driven cognitive resources that are needed for the normal operation of the reflective system and for exercising the willpower to resist drugs.

Effect of changing of the parameters of the cable network of monitoring systems of high-rise buildings on the basis of string converters on their operability

NASA Astrophysics Data System (ADS)

Gusev, Nikolay; Svatovskaya, Larisa; Kucherenko, Alexandr

2018-03-01

The article is devoted to the problem of improving the reliability of monitoring systems for the technical conditions of high-rise buildings. The improvement is based on string sensors with an impulsed excitation method ensuring the maximum signal-to-noise ratio at their output. The influence of the parameters of the monitoring system on the shape of the excitation impulses of the string, and, consequently, on the amplitude of the string vibration of the string converter is also considered in the article. It has been experimentally proved that the parameters of the excitation impulses of the string converters. The article presents the results of the experiments showing the effect of the fronts duration of the excitation impulses on the amplitude of the oscillations of the strings. The influence of the fronts duration of the excitation impulse with the frontal lengths up to 0.5 ms is studied at the excitation impulse duration not exceeding 0.5 times the duration of natural oscillation periods of the string. The experimental data are compared with the theoretical ones and hypotheses explaining their difference are advanced. The article suggests some methods of reducing the influence of the cable-switching equipment system parameters on the amplitude of string oscillations. The possibilities of improving the reliability of the systems developed on the basis of string sensors with an impulsed excitation method and used for monitoring the technical conditions of the high-rise buildings are proposed.

Optimization of valve opening process for the suppression of impulse exhaust noise

NASA Astrophysics Data System (ADS)

Li, Jingxiang; Zhao, Shengdun

2017-02-01

Impulse exhaust noise generated by the sudden impact of discharging flow of pneumatic systems has significant temporal characteristics including high sound pressure and rapid sound transient. The impulse noise exposures are more hazardous to hearing than the energy equivalent uniform noise exposures. This paper presents a novel approach to suppress the peak sound pressure as a major indicator of impulsiveness of the impulse exhaust noise by an optimization of the opening process of valve. Relationships between exhaust flow and impulse noise are described by thermodynamics and noise generating mechanism. Then an optimized approach by controlling the valve opening process is derived under a constraint of pre-setting exhaust time. A modified servo-direct-driven valve was designed and assembled in a typical pneumatic system for the verification experiments comparing with an original solenoid valve. Experimental results with groups of initial cylinder pressures and pre-setting exhaust times are shown to verify the effects of the proposed optimization. Some indicators of energy-equivalent and impulsiveness are introduced to discuss the effects of the noise suppressions. Relationship between noise reduction and exhaust time delay is also discussed.

HITCal: a software tool for analysis of video head impulse test responses.

PubMed

Rey-Martinez, Jorge; Batuecas-Caletrio, Angel; Matiño, Eusebi; Perez Fernandez, Nicolás

2015-09-01

The developed software (HITCal) may be a useful tool in the analysis and measurement of the saccadic video head impulse test (vHIT) responses and with the experience obtained during its use the authors suggest that HITCal is an excellent method for enhanced exploration of vHIT outputs. To develop a (software) method to analyze and explore the vHIT responses, mainly saccades. HITCal was written using a computational development program; the function to access a vHIT file was programmed; extended head impulse exploration and measurement tools were created and an automated saccade analysis was developed using an experimental algorithm. For pre-release HITCal laboratory tests, a database of head impulse tests (HITs) was created with the data collected retrospectively in three reference centers. This HITs database was evaluated by humans and was also computed with HITCal. The authors have successfully built HITCal and it has been released as open source software; the developed software was fully operative and all the proposed characteristics were incorporated in the released version. The automated saccades algorithm implemented in HITCal has good concordance with the assessment by human observers (Cohen's kappa coefficient = 0.7).

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.

Hyaluronan modulates TRPV1 channel opening, reducing peripheral nociceptor activity and pain

PubMed Central

Caires, Rebeca; Luis, Enoch; Taberner, Francisco J.; Fernandez-Ballester, Gregorio; Ferrer-Montiel, Antonio; Balazs, Endre A.; Gomis, Ana; Belmonte, Carlos; de la Peña, Elvira

2015-01-01

Hyaluronan (HA) is present in the extracellular matrix of all body tissues, including synovial fluid in joints, in which it behaves as a filter that buffers transmission of mechanical forces to nociceptor nerve endings thereby reducing pain. Using recombinant systems, mouse-cultured dorsal root ganglia (DRG) neurons and in vivo experiments, we found that HA also modulates polymodal transient receptor potential vanilloid subtype 1 (TRPV1) channels. HA diminishes heat, pH and capsaicin (CAP) responses, thus reducing the opening probability of the channel by stabilizing its closed state. Accordingly, in DRG neurons, HA decreases TRPV1-mediated impulse firing and channel sensitization by bradykinin. Moreover, subcutaneous HA injection in mice reduces heat and capsaicin nocifensive responses, whereas the intra-articular injection of HA in rats decreases capsaicin joint nociceptor fibres discharge. Collectively, these results indicate that extracellular HA reduces the excitability of the ubiquitous TRPV1 channel, thereby lowering impulse activity in the peripheral nociceptor endings underlying pain. PMID:26311398

Fronto-striatal circuits in response-inhibition: Relevance to addiction

PubMed Central

Morein-Zamir, Sharon; Robbins, Trevor W.

2015-01-01

Disruptions to inhibitory control are believed to contribute to multiple aspects of drug abuse, from preexisting vulnerability in at-risk individuals, through escalation to dependence, to promotion of relapse in chronic users. Paradigms investigating the suppression of actions have been investigated in animal and human research on drug addiction. Rodent research has focused largely on impulsive behaviors, often gauged by premature responding, as a viable model highlighting the relevant role of dopamine and other neurotransmitters primarily in the striatum. Human research on action inhibition in stimulant dependence has highlighted impaired performance and largely prefrontal cortical abnormalities as part of a broader pattern of cognitive abnormalities. Animal and human research implicate inhibitory difficulties mediated by fronto-striatal circuitry both preceding and as a result of excessive stimulus use. In this regard, response-inhibition has proven a useful cognitive function to gauge the integrity of fronto-striatal systems and their role in contributing to impulsive and compulsive features of drug dependence. This article is part of a Special Issue entitled SI:Addiction circuits. PMID:25218611

The influence of signal type on the internal auditory representation of a room

NASA Astrophysics Data System (ADS)

Teret, Elizabeth

Currently, architectural acousticians make no real distinction between a room impulse response and the auditory system's internal representation of a room. With this lack of a good model for the auditory representation of a room, it is indirectly assumed that our internal representation of a room is independent of the sound source needed to make the room characteristics audible. The extent to which this assumption holds true is examined with perceptual tests. Listeners are presented with various pairs of signals (music, speech, and noise) convolved with synthesized impulse responses of different reverberation times. They are asked to adjust the reverberation of one of the signals to match the other. Analysis of the data show that the source signal significantly influences perceived reverberance. Listeners are less accurate when matching reverberation times of varied signals than they are with identical signals. Additional testing shows that perception of reverberation can be linked to the existence of transients in the signal.

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).

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.

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

77 FR 33724 - Submission for OMB Review; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-07

... and OMB Number: Assessing Human Response to Military Impulse Noise; OMB Control Number 0710-TBD. Type... community annoyance and complaints, related to impulsive noise from military installations. The [[Page 33725... the need for training operations at military installations with public safety and welfare. Affected...

Anatomical and functional organization of the human substantia nigra and its connections

PubMed Central

Zhang, Yu; Larcher, Kevin Michel-Herve; Misic, Bratislav

2017-01-01

We investigated the anatomical and functional organization of the human substantia nigra (SN) using diffusion and functional MRI data from the Human Connectome Project. We identified a tripartite connectivity-based parcellation of SN with a limbic, cognitive, motor arrangement. The medial SN connects with limbic striatal and cortical regions and encodes value (greater response to monetary wins than losses during fMRI), while the ventral SN connects with associative regions of cortex and striatum and encodes salience (equal response to wins and losses). The lateral SN connects with somatomotor regions of striatum and cortex and also encodes salience. Behavioral measures from delay discounting and flanker tasks supported a role for the value-coding medial SN network in decisional impulsivity, while the salience-coding ventral SN network was associated with motor impulsivity. In sum, there is anatomical and functional heterogeneity of human SN, which underpins value versus salience coding, and impulsive choice versus impulsive action. PMID:28826495

BIS impulsivity and acute nicotine exposure are associated with discounting global consequences in the Harvard game.

PubMed

Hogarth, Lee; Stillwell, David J; Tunney, Richard J

2013-01-01

The Barratt Impulsivity Scale (BIS) provides a transdiagnostic marker for a number of psychiatric conditions and drug abuse, but the precise psychological trait(s) tapped by this questionnaire remain obscure. To address this, 51 smokers completed in counterbalanced order the BIS, a delay discounting task and a Harvard game that measured choice between a response that yielded a high immediate monetary payoff but decreased opportunity to earn money overall (local choice) versus a response that yielded a lower immediate payoff but afforded a greater opportunity to earn overall (global choice). Individual level of BIS impulsivity and self-elected smoking prior to the study were independently associated with increased preference for the local over the global choice in the Harvard game, but not delay discounting. BIS impulsivity and acute nicotine exposure reflect a bias in the governance of choice by immediate reward contingencies over global consequences, consistent with contemporary dual-process instrumental learning theories. Copyright © 2013 John Wiley & Sons, Ltd.

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).

Transcranial Magnetic Stimulation: Decomposing the Processes Underlying Action Preparation.

PubMed

Bestmann, Sven; Duque, Julie

2016-08-01

Preparing actions requires the operation of several cognitive control processes that influence the state of the motor system to ensure that the appropriate behavior is ultimately selected and executed. For example, some form of competition resolution ensures that the right action is chosen among alternatives, often in the presence of conflict; at the same time, impulse control ought to be deployed to prevent premature responses. Here we review how state-changes in the human motor system during action preparation can be studied through motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation over the contralateral primary motor cortex (M1). We discuss how the physiological fingerprints afforded by MEPs have helped to decompose some of the dynamic and effector-specific influences on the motor system during action preparation. We focus on competition resolution, conflict and impulse control, as well as on the influence of higher cognitive decision-related variables. The selected examples demonstrate the usefulness of MEPs as physiological readouts for decomposing the influence of distinct, but often overlapping, control processes on the human motor system during action preparation. © The Author(s) 2015.

Lp-stability (1 less than or equal to p less than or equal to infinity) of multivariable nonlinear time-varying feedback systems that are open-loop unstable. [noting unstable convolution subsystem forward control and time varying nonlinear feedback

NASA Technical Reports Server (NTRS)

Callier, F. M.; Desoer, C. A.

1973-01-01

A class of multivariable, nonlinear time-varying feedback systems with an unstable convolution subsystem as feedforward and a time-varying nonlinear gain as feedback was considered. The impulse response of the convolution subsystem is the sum of a finite number of increasing exponentials multiplied by nonnegative powers of the time t, a term that is absolutely integrable and an infinite series of delayed impulses. The main result is a theorem. It essentially states that if the unstable convolution subsystem can be stabilized by a constant feedback gain F and if incremental gain of the difference between the nonlinear gain function and F is sufficiently small, then the nonlinear system is L(p)-stable for any p between one and infinity. Furthermore, the solutions of the nonlinear system depend continuously on the inputs in any L(p)-norm. The fixed point theorem is crucial in deriving the above theorem.

Factors of psychopathy and electrocortical response to emotional pictures: Further evidence for a two-process theory.

PubMed

Venables, Noah C; Hall, Jason R; Yancey, James R; Patrick, Christopher J

2015-05-01

The Two-Process theory of psychopathy posits that distinct etiological mechanisms contribute to the condition: (a) a weakness in defensive (fear) reactivity related to affective-interpersonal features, and (b) impaired cognitive-executive functioning, marked by reductions in brain responses such as P3, related to impulsive-antisocial features. The current study examined relations between psychopathy factors and electrocortical response to emotional and neutral pictures in male offenders (N = 139) assessed using the Psychopathy Checklist-Revised (PCL-R). Impulsive-antisocial features of the PCL-R (Factor 2) were associated with reduced amplitude of earlier P3 brain response to pictures regardless of valence, whereas the affective-interpersonal dimension (Factor 1) was associated specifically with reductions in late positive potential response to aversive pictures. Findings provide further support for the Two-Process theory and add to a growing body of evidence linking the impulsive-antisocial facet of psychopathy to the broader construct of externalizing proneness. Findings are discussed in terms of current initiatives directed at incorporating neuroscientific concepts into psychopathology classification. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

Factors of Psychopathy and Electrocortical Response to Emotional Pictures: Further Evidence for a Two-Process Theory

PubMed Central

Venables, Noah C.; Hall, Jason R.; Yancey, James R.; Patrick, Christopher J.

2014-01-01

The Two-Process theory of psychopathy posits distinct etiological mechanisms contribute to the disorder: 1) a weakness in defensive (fear) reactivity related to affective-interpersonal features, and 2) impaired cognitive-executive functioning, marked by reductions in brain responses such as P3, related to impulsive-antisocial features. The current study examined relations between psychopathy factors and electrocortical response to emotional and neutral pictures in male offenders (N=139) assessed using the Psychopathy Checklist-Revised (PCL-R). Impulsive-antisocial features of the PCL-R (Factor 2) were associated with reduced amplitude of earlier P3 brain response to pictures regardless of valence, whereas the affective-interpersonal dimension (Factor 1) was associated specifically with reductions in late positive potential response to aversive pictures. Findings provide further support for the Two-Process theory and add to a growing body of evidence linking the impulsive-antisocial facet of psychopathy to the broader construct of externalizing proneness. Findings are discussed in terms of current initiatives directed at incorporating neuroscientific concepts into psychopathology classification. PMID:25603361

Topological phase transition measured in a dissipative metamaterial

NASA Astrophysics Data System (ADS)

Rosenthal, Eric I.; Ehrlich, Nicole K.; Rudner, Mark S.; Higginbotham, Andrew P.; Lehnert, K. W.

2018-06-01

We construct a metamaterial from radio-frequency harmonic oscillators, and find two topologically distinct phases resulting from dissipation engineered into the system. These phases are distinguished by a quantized value of bulk energy transport. The impulse response of our circuit is measured and used to reconstruct the band structure and winding number of circuit eigenfunctions around a dark mode. Our results demonstrate that dissipative topological transport can occur in a wider class of physical systems than considered before.

Enhanced inhibitory control by neuropeptide Y Y5 receptor blockade in rats.

PubMed

Bari, A; Dec, A; Lee, A W; Lee, J; Song, D; Dale, E; Peterson, J; Zorn, S; Huang, X; Campbell, B; Robbins, T W; West, A R

2015-03-01

The neuropeptide Y (NPY) system acts in synergy with the classic neurotransmitters to regulate a large variety of functions including autonomic, affective, and cognitive processes. Research on the effects of NPY in the central nervous system has focused on food intake control and affective processes, but growing evidence of NPY involvement in attention-deficit/hyperactivity disorder (ADHD) and other psychiatric conditions motivated the present study. We tested the effects of the novel and highly selective NPY Y5 receptor antagonist Lu AE00654 on impulsivity and the underlying cortico-striatal circuitry in rats to further explore the possible involvement of the NPY system in pathologies characterized by inattention and impulsive behavior. A low dose of Lu AE00654 (0.03 mg/kg) selectively facilitated response inhibition as measured by the stop-signal task, whereas no effects were found at higher doses (0.3 and 3 mg/kg). Systemic administration of Lu AE00654 also enhanced the inhibitory influence of the dorsal frontal cortex on neurons in the caudate-putamen, this fronto-striatal circuitry being implicated in the executive control of behavior. Finally, by locally injecting a Y5 agonist, we observed reciprocal activation between dorsal frontal cortex and caudate-putamen neurons. Importantly, the effects of the Y5 agonist were attenuated by pretreatment with Lu AE00654, confirming the presence of Y5 binding sites modulating functional interactions within frontal-subcortical circuits. These results suggest that the NPY system modulates inhibitory neurotransmission in brain areas important for impulse control, and may be relevant for the treatment of pathologies such as ADHD and drug abuse.

Rearing practices and impulsivity/hyperactivity symptoms in relation to inflated responsibility and obsessive-compulsive symptoms.

PubMed

Smári, Jakob; Martinsson, Davíð Rúrik; Einarsson, Hjalti

2010-10-01

The aim of the study was to investigate potential precursors of inflated responsibility (responsibility attitudes) and obsessive-compulsive (OCD) symptoms. It was argued that both parental overprotection and impulsivity, separately and in interaction with each other, contribute to inflated responsibility and OCD symptoms. In a large sample of young adults (N = 570), self-report measures of OCD symptoms (OCI-R), responsibility attitudes (RAS), anxiety/depression (HADS), rearing practices (EMBU), present and past impulsivity/hyperactivity symptoms (IMP/HY) were administered. Overprotection as well as IMP/HY were found to predict OCD symptoms as well as inflated responsibility. Finally, a significant interaction was found between IMP/HY and overprotection with regard to both OCD symptoms and inflated responsibility. This effect reflected that IMP/HY was more strongly related to OCD symptoms and responsibility in people who had not been overprotected than in people who had been. Conversely overprotection was related to OCD symptoms and responsibility in people low but not in people high in IMP/HY. The results seem to indicate that the inadequacy between offer and need for parental control may play a role in the development of OCD symptoms. © 2010 The Authors. Scandinavian Journal of Psychology © 2010 The Scandinavian Psychological Associations.

Targeted isometric force impulses in patients with traumatic brain injury reveal delayed motor programming and change of strategy.

PubMed

Cantagallo, Anna; Di Russo, Francesco; Favilla, Marco; Zoccolotti, Pierluigi

2015-04-15

The capability of quickly (as soon as possible) producing fast uncorrected and accurate isometric force impulses was examined to assess the motor efficiency of patients with moderate to severe traumatic brain injury (TBI) and good motor recovery at a clinical evaluation. Twenty male right-handed patients with moderate to severe TBI and 24 age-matched healthy male right-handed controls participated in the study. The experimental task required subjects to aim brief and uncorrected isometric force impulses to targets visually presented along with subjects' force displays. Both TBI patients and controls were able to produce force impulses whose mean peak amplitudes varied proportionally to the target load with no detectable group difference. Patients with TBI, however, were slower than controls in initiating their responses (reaction times [RTs] were longer by 125 msec) and were also slower during the execution of their motor responses, reaching the peak forces requested 23 msec later than controls (time to peak force: 35% delay). Further, their mean dF/dt (35 kg/sec) was slower than that of controls (53 kg/sec), again indicating a 34% impairment with respect to controls. Overall, patients with TBI showed accurate but delayed and slower isometric force impulses. Thus, an evaluation taking into account also response time features is more effective in picking up motor impairments than the standard clinical scales focusing on accuracy of movement only.

Binaural room simulation

NASA Technical Reports Server (NTRS)

Lehnert, H.; Blauert, Jens; Pompetzki, W.

1991-01-01

In every-day listening the auditory event perceived by a listener is determined not only by the sound signal that a sound emits but also by a variety of environmental parameters. These parameters are the position, orientation and directional characteristics of the sound source, the listener's position and orientation, the geometrical and acoustical properties of surfaces which affect the sound field and the sound propagation properties of the surrounding fluid. A complete set of these parameters can be called an Acoustic Environment. If the auditory event perceived by a listener is manipulated in such a way that the listener is shifted acoustically into a different acoustic environment without moving himself physically, a Virtual Acoustic Environment has been created. Here, we deal with a special technique to set up nearly arbitrary Virtual Acoustic Environments, the Binaural Room Simulation. The purpose of the Binaural Room Simulation is to compute the binaural impulse response related to a virtual acoustic environment taking into account all parameters mentioned above. One possible way to describe a Virtual Acoustic Environment is the concept of the virtual sound sources. Each of the virtual sources emits a certain signal which is correlated but not necessarily identical with the signal emitted by the direct sound source. If source and receiver are non moving, the acoustic environment becomes a linear time-invariant system. Then, the Binaural Impulse Response from the source to a listener' s eardrums contains all relevant auditory information related to the Virtual Acoustic Environment. Listening into the simulated environment can easily be achieved by convolving the Binaural Impulse Response with dry signals and representing the results via headphones.

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

PubMed

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

2015-03-01

Given the potential negative mental health consequences of pathological video gaming, understanding its etiology may lead to useful treatment developments. The purpose of the study was to examine the influence of impulsive and regulatory processes on pathological video gaming. Study 1 involved 2154 students from 6 primary and 4 secondary schools in Singapore. Study 2 involved 191 students from 2 secondary schools. The results of study 1 and study 2 supported the hypothesis that self-regulation is a mediator between impulsivity and pathological video gaming. Specifically, higher levels of impulsivity was related to lower levels of self-regulation, which in turn was related to higher levels of pathological video gaming. The use of impulsivity and self-regulation in predicting pathological video gaming supports the dual-system model of incorporating both impulsive and reflective systems in the prediction of self-control outcomes. The study highlights the development of self-regulatory resources as a possible avenue for future prevention and treatment research. © 2011 APJPH.

Electrostatic Plasma Accelerator (EPA)

NASA Technical Reports Server (NTRS)

Brophy, John R.; Aston, Graeme

1995-01-01

The application of electric propulsion to communications satellites, however, has been limited to the use of hydrazine thrusters with electric heaters for thrust and specific impulse augmentation. These electrothermal thrusters operate at specific impulse levels of approximately 300 s with heater powers of about 500 W. Low power arcjets (1-3 kW) are currently being investigated as a way to increase specific impulse levels to approximately 500 s. Ion propulsion systems can easily produce specific impulses of 3000 s or greater, but have yet to be applied to communications satellites. The reasons most often given for not using ion propulsion systems are their high level of overall complexity, low thrust with long burn times, and the difficulty of integrating the propulsion system into existing commercial spacecraft busses. The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass.

Suppression of radiating harmonics Electro-Impulse Deicing (EIDI) systems

NASA Astrophysics Data System (ADS)

Zieve, Peter; Ng, James; Fiedberg, Robert

1991-10-01

The electromagnetic compatibility (EMC) of two different configurations of electromagnetic deicing systems is discussed. Both Electro-Impulse Deicing (EIDI) and Eddy Current Repulsion Deicing Strip (EDS) are investigated. With EIDI, rigid coils are mounted behind the wing; while with EDS, the impulse coils are built thin and flexible with printed circuit board technology. An important consideration in the certification of electromagnetic impulse deicing systems is electromagnetic compatibility (EMC). When the capacitor bank discharges, a large current pulse travels down a transmission line to the coil. The coil is one source of radiation. Another source is the cabling and connections to the coil. In work conducted for the FAA in 1988, it was found that excessive electromagnetic emissions resulted from the operation of a Low Voltage Electro-Impulse Deicer (LVEID) in conjunction with a composite wing. The goal of this project was to investigate and develop techniques for controlling emissions without the benefit of shielding. In this study it was determined that both EIDI and EDS could be brought within the RTCA/DO-160B standards through proper shielding and termination of the pulse power cable. An alternative topology of EDS with the impulse coil on the wing exterior surface did not meet the standard.

The association of Internet addiction symptoms with impulsiveness, loneliness, novelty seeking and behavioral inhibition system among adults with attention-deficit/hyperactivity disorder (ADHD).

PubMed

Li, Wendi; Zhang, Wei; Xiao, Lin; Nie, Jia

2016-09-30

The aims of this study were to test the associations of the Internet addiction symptoms with impulsiveness, loneliness, novelty seeking and behavioral inhibition systems among adults with attention-deficit/hyperactivity disorder (ADHD) and adults with non-ADHD. A total of 146 adults aged between 19 and 33 years involved in this study. Participants were assessed with the Chinese version of the adult ADHD Self-report scale (ASRS), the Revised Chen Internet Addiction Scale (CIAS-R), the Barratt Impulsiveness Scale 11 (BIS-11), the Tridimensional Personality Questionnaire (TPQ), the UCLA loneliness scale, and the Behavioral Inhibition System and Behavioral Activation System Scale (BIS/BAS Scale). The results of hierarchical regression analysis indicated that impulsiveness, loneliness, and behavioral inhibition system were significant predictors of Internet addition among adults with ADHD. Higher loneliness was significantly associated with more severe Internet addition symptoms among the non-ADHD group. Adults with high impulsiveness, loneliness, and BIS should be treated with caution for preventing Internet addiction. In addition, adults with and without ADHD should be provided with different preventative strategies. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Executive functions, impulsivity, and inhibitory control in adolescents: A structural equation model

PubMed Central

Fino, Emanuele; Melogno, Sergio; Iliceto, Paolo; D’Aliesio, Sara; Pinto, Maria Antonietta; Candilera, Gabriella; Sabatello, Ugo

2014-01-01

Background. Adolescence represents a critical period for brain development, addressed by neurodevelopmental models to frontal, subcortical-limbic, and striatal activation, a pattern associated with rise of impulsivity and deficits in inhibitory control. The present study aimed at studying the association between self-report measures of impulsivity and inhibitory control with executive function in adolescents, employing structural equation modeling. Method. Tests were administered to 434 high school students. Acting without thinking was measured through the Barratt Impulsiveness Scale and the Dickman Impulsivity Inventory, reward sensitivity through the Behavioral Activation System, and sensation seeking through the Zuckerman–Kuhlman–Aluja Personali- ty Questionnaire. Inhibitory control was assessed through the Behavioral Inhibition System. The performance at the Wisconsin Card Sorting Task indicated executive function. Three models were specified using Sample Covariance Matrix, and the estimated parameters using Maximum Likelihood. Results. In the final model, impulsivity and inhibitory control predicted executive function, but sensation seeking did not. The fit of the model to data was excellent. Conclusions. The hypothesis that inhibitory control and impulsivity are predictors of executive function was supported. Our results appear informative of the validity of self-report measures to examine the relation between impulsivity traits rather than others to regulatory function of cognition and behavior. PMID:25157298

Signaling When (and When Not) to Be Cautious and Self-Protective: Impulsive and Reflective Trust in Close Relationships

PubMed Central

Murray, Sandra L.; Pinkus, Rebecca T.; Holmes, John G.; Harris, Brianna; Gomillion, Sarah; Aloni, Maya; Derrick, Jaye L.; Leder, Sadie

2011-01-01

A dual process model is proposed to explain how automatic evaluative associations to the partner (i.e., impulsive trust) and deliberative expectations of partner caring (i.e., reflective trust) interact to govern self-protection in romantic relationships. Experimental and correlational studies of dating and marital relationships supported the model. Subliminally conditioning more positive evaluative associations to the partner increased confidence in the partner’s caring, suggesting that trust has an impulsive basis. Being high on impulsive trust (i.e., more positive evaluative associations to the partner on the IAT) also reduced the automatic inclination to distance in response to doubts about the partner’s trustworthiness. It similarly reduced self-protective behavioral reactions to these reflective trust concerns. The studies further revealed that the effects of impulsive trust depend on working memory capacity: Being high on impulsive trust inoculated against reflective trust concerns for people low on working memory capacity. PMID:21443370

Impulse Testing of Corporate-Fed Patch Array Antennas

NASA Technical Reports Server (NTRS)

Chamberlain, Neil F.

2011-01-01

This paper discusses a novel method for detecting faults in antenna arrays. The method, termed Impulse Testing, was developed for corporate-fed patch arrays where the element is fed by a probe and is shorted at its center. Impulse Testing was devised to supplement conventional microwave measurements in order to quickly verify antenna integrity. The technique relies on exciting each antenna element in turn with a fast pulse (or impulse) that propagates through the feed network to the output port of the antenna. The resulting impulse response is characteristic of the path through the feed network. Using an oscilloscope, a simple amplitude measurement can be made to detect faults. A circuit model of the antenna elements and feed network was constructed to assess various fault scenarios and determine fault-detection thresholds. The experimental setup and impulse measurements for two patch array antennas are presented. Advantages and limitations of the technique are discussed along with applications to other antenna array topologies

Cognitive and behavioural dispositions in offspring at high risk for alcoholism.

PubMed

Kumar, Rajesh; Kumar, Keshav Janakiprasad; Benegal, Vivek

2018-06-01

Offspring with family history of alcoholism are considered to be at high risk for alcoholism. The present study sought to expand our understanding of cognitive and behavioural dispositions associated with executive control and self-regulation in alcohol naïve offspring with and without family history of alcoholism. Sample comprised of alcohol naive offspring in two groups: (i) at high risk (n = 34) and (ii) at low risk for alcoholism (n = 34). Both groups were matched on age (+/-1 year), education (+/-1 year) and gender. Measures used were: Mini-International Neuropsychiatric Interview, Family Interview for Genetic Studies, Socio-demographic Data Sheet, Annett's Handedness Questionnaire, Barratt's Impulsiveness Scale-version 11, Digit Span Test, Spatial Span Test, Tower of London, Wisconsin Card Sorting Test, Iowa Gambling Task (IGT) and Game of Dice Task (GDT). Results showed that alcohol naive offspring at high risk for alcoholism reported significantly high impulsivity and demonstrated significant differences on executive functions and decision making tasks. Correlation analysis revealed that high impulsivity was significantly associated with poor performance on explicit decision making task (GDT) and executive function task (WCST). There was no significant correlation between two decision making tasks (IGT and GDT) in both groups and performance on IGT was not significantly associated with impulsivity and executive functions. The present study indicates cognitive and behavioural dispositions in alcohol naive offspring at high risk for alcoholism and support the sub-optimal balance between reflective and impulsive system responsible for addiction. Furthermore, present study supports separability between two different types of decision making tasks. Copyright © 2018 Elsevier B.V. All rights reserved.

A-law/Mu-law Dynamic Range Compression Deconvolution (Preprint)

DTIC Science & Technology

2008-02-04

noise filtering via the spectrum proportionality filter, and second the signal deblurring via the inverse filter. In this process for regions when...is the joint image of motion impulse response and the noisy blurred image with signal to noise ratio 5, 6(A’) is the gray level recovered image...joint image of motion impulse response and the noisy blurred image with signal to noise ratio 5, (A’) the gray level recovered image using the A-law

Resonance of a fluid-driven crack: radiation properties and implications for the source of long-period events and harmonic tremor.

USGS Publications Warehouse

Chouet, B.

1988-01-01

A dynamic source model is presented, in which a 3-D crack containing a viscous compressible fluid is excited into resonance by an impulsive pressure transient applied over a small area DELTA S of the crack surface. The crack excitation depends critically on two dimensionless parameters called the crack stiffness and viscous damping loss. According to the model, the long-period event and harmonic tremor share the same source but differ in the boundary conditions for fluid flow and in the triggering mechanism setting up the resonance of the source, the former being viewed as the impulse response of the tremor generating system and the later representing the excitation due to more complex forcing functions.-from Author

Magnetospheric electric fields and currents

NASA Technical Reports Server (NTRS)

Mauk, B. H.; Zanetti, L. J.

1987-01-01

The progress made in the years 1983-1986 in understanding the character and operation of magnetospheric electric fields and electric currents is discussed, with emphasis placed on the connection with the interior regions. Special attention is given to determinations of global electric-field configurations, measurements of the response of magnetospheric particle populations to the electric-field configurations, and observations of the magnetospheric currents at high altitude and during northward IMF. Global simulations of current distributions are discussed, and the sources of global electric fields and currents are examined. The topics discussed in the area of impulsive and small-scale phenomena include substorm current systems, impulsive electric fields and associated currents, and field-aligned electrodynamics. A key finding of these studies is that the electric fields and currents are interrelated and cannot be viewed as separate entities.

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.

Variability in the control of head movements in seated humans: a link with whiplash injuries?

PubMed Central

Vibert, N; MacDougall, H G; de Waele, C; Gilchrist, D P D; Burgess, A M; Sidis, A; Migliaccio, A; Curthoys, I S; Vidal, P P

2001-01-01

The aim of this study was to determine how context and on-line sensory information are combined to control posture in seated subjects submitted to high-jerk, passive linear accelerations. Subjects were seated with eyes closed on a servo-controlled linear sled. They were asked to relax and received brief accelerations either sideways or in the fore-aft direction. The stimuli had an abrupt onset, comparable to the jerk experienced during a minor car collision. Rotation and translation of the head and body were measured using an Optotrak system. In some of the subjects, surface electromyographic (EMG) responses of selected neck and/or back muscles were recorded simultaneously. For each subject, responses were highly stereotyped from the first trial, and showed little sign of habituation or sensitisation. Comparable results were obtained with sideways and fore-aft accelerations. During each impulse, the head lagged behind the trunk for several tens of milliseconds. The subjects' head movement responses were distributed as a continuum in between two extreme categories. The ‘stiff’ subjects showed little rotation or translation of the head relative to the trunk for the whole duration of the impulse. In contrast, the ‘floppy’ subjects showed a large roll or pitch of the head relative to the trunk in the direction opposite to the sled movement. This response appeared as an exaggerated ‘inertial’ response to the impulse. Surface EMG recordings showed that most of the stiff subjects were not contracting their superficial neck or back muscles. We think they relied on bilateral contractions of their deep, axial musculature to keep the head-neck ensemble in line with the trunk during the movement. About half of the floppy subjects displayed reflex activation of the neck muscles on the side opposite to the direction of acceleration, which occurred before or during the head movement and tended to exaggerate it. The other floppy subjects seemed to rely on only the passive biomechanical properties of their head-neck ensemble to compensate for the perturbation. In our study, proprioception was the sole source of sensory information as long as the head did not move. We therefore presume that the EMG responses and head movements we observed were mainly triggered by the activation of stretch receptors in the hips, trunk and/or neck. The visualisation of an imaginary reference in space during sideways impulses significantly reduced the head roll exhibited by floppy subjects. This suggests that the adoption by the central nervous system of an extrinsic, ‘allocentric’ frame of reference instead of an intrinsic, ‘egocentric’ one may be instrumental for the selection of the stiff strategy. The response of floppy subjects appeared to be maladaptive and likely to increase the risk of whiplash injury during motor vehicle accidents. Evolution of postural control may not have taken into account the implications of passive, high-acceleration perturbations affecting seated subjects. PMID:11313451

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

Intercultural Education and the Crisis of Globalisation: Some Reflections

ERIC Educational Resources Information Center

Coulby, David

2011-01-01

In this essay I reflect on the role of intercultural education in an emerging global crisis. Education systems are characterised by both divergent and convergent impulses. Divergent impulses include tradition, nationalism and religion. Convergent impulses (isomorphism) include science and technology, culture (including the English language),…

Investigating Glutamatergic Mechanism in Attention and Impulse Control Using Rats in a Modified 5-Choice Serial Reaction Time Task

PubMed Central

Benn, Abigail; Robinson, Emma S. J.

2014-01-01

The 5-choice serial reaction time task (5CSRTT) has been widely used to study attention and impulse control in rodents. In order to mimic cognitive impairments in psychiatry, one approach has been to use acute administration of NMDA antagonists. This disruption in glutamatergic transmission leads to impairments in accuracy, omissions, and premature responses although findings have been inconsistent. In this study, we further investigated glutamatergic mechanisms using a novel version of the 5CSRTT, which we have previously shown to be more sensitive to cognitive enhancers. We first investigated the effects of systemic treatment with NMDA antagonists. We also carried out a preliminary investigation using targeted medial prefrontal cortex infusions of a NMDA antagonist (MK801), mGluR2/3 antagonist (LY341495), and mGluR7 negative allosteric modulator (MMPIP). Acute systemic administration of the different NMDA antagonists had no specific effects on accuracy. At higher doses PCP, ketamine, and memantine, increased omissions and affected other measures suggesting a general disruption in task performance. Only MK801 increased premature responses, and reduced omissions at lower doses suggesting stimulant like effects. None of the NMDA antagonists affected accuracy or any other measures when tested using a short stimulus challenge. Infusions of MK801 had no effect on accuracy but increased premature responses following infralimbic, but not prelimbic infusion. LY341495 had no effects in either brain region but a decrease in accuracy was observed following prelimbic infusion of MMPIP. Contrary to our hypothesis, disruptions to glutamate transmission using NMDA antagonists did not induce any clear deficits in accuracy in this modified version of the 5CSRTT. We also found that the profile of effects for MK801 differed from those observed with PCP, ketamine, and memantine. The effects of MK801 in the infralimbic cortex add to the literature indicating this brain region and glutamate play an important role in impulse control. PMID:25526617

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

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.

Current evaluation of the tripropellant concept

NASA Technical Reports Server (NTRS)

Zurawski, R. L.

1986-01-01

An analytical study was conducted to determine the specific-impulse advantages of adding metals to conventional liquid-bipropellant systems. These tripropellant systems theoretically offer higher specific impulse and increased propellant density compared with bipropellant systems. Metals considered were Be, Li, and Al. Bipropellant systems were H2/O2, N2H4/N2O4, RP-1/O2, and H2/F2. Thermochemical calculations were performed for sea-level expansion from 6.895-MN/sq. m. (1000-psia) chamber pressure over a wide range of mixture ratios and propellant compositions. Three-dimensional plots characterize the specific impulse of each tripropellant system. Technology issues pertinent to metallized propellant systems are discussed.

A spline-based approach for computing spatial impulse responses.

PubMed

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

2007-05-01

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

ELECTRICAL LOAD ANTICIPATOR AND RECORDER

DOEpatents

Werme, J.E.

1961-09-01

A system is described in which an indication of the prevailing energy consumption in an electrical power metering system and a projected power demand for one demand in terval is provided at selected increments of time within the demand interval. Each watt-hour meter in the system is provided with an impulse generator that generates two impulses for each revolution of the meter disc. In each demand interval, for example, one half-hour, of the metering system, the total impulses received from all of the meters are continuously totaled for each 5-minute interval and multiplied by a number from 6 to 1 depending upon which 5- minute interval the impulses were received. This value is added to the total pulses received in the intervals preceding the current 5-minute interval within the half-hour demand interval tc thereby provide an indication of the projected power demand every 5 minutes in the demand interval.

Impulsive aggression, delay discounting, and adolescent suicide attempts: effects of current psychotropic medication use and family history of suicidal behavior.

PubMed

Bridge, Jeffrey A; Reynolds, Brady; McBee-Strayer, Sandra M; Sheftall, Arielle H; Ackerman, John; Stevens, Jack; Mendoza, Kristen; Campo, John V; Brent, David A

2015-03-01

Impulsive-aggressive behaviors have been consistently implicated in the phenomenology, neurobiology, and familial aggregation of suicidal behavior. The purpose of this study was to extend previous work by examining laboratory behavioral measures of delayed reward impulsivity and impulsive aggression in adolescent suicide attempters and never-suicidal comparison subjects. Using the Point Subtraction Aggression Paradigm (PSAP) and the Delay Discounting Task (DDQ), the authors examined delay discounting and impulsive aggression in 40 adolescent suicide attempters, ages 13-18, and 40 never-suicidal, demographically matched psychiatric comparison subjects. Overall, suicide attempters and comparison subjects performed similarly on the PSAP and DDQ. There was a significant group by current psychotropic medication use interaction (p=0.013) for mean aggressive responses on the PSAP. Group comparisons revealed that attempters emitted more aggressive responses per provocation than comparison subjects, only in those not on psychotropic medication (p=0.049), whereas for those currently treated with psychotropic medication, there were no group differences (p>0.05). This interaction effect was specific to current antidepressant use. Among all subjects, family history of suicidal behavior (suicide or suicide attempt) in first degree relatives was significantly correlated with both delay discounting (r=-0.22, p=0.049), and aggressive responding (r=0.27, p=0.015). Family history of suicidal behavior was associated with delay discounting, but not with aggressive responding on the PSAP, after controlling for relevant covariates. In this study, impulsive-aggressive responding was associated with suicide attempt only in those not being treated with antidepressants. Future work to replicate and extend these findings could have important therapeutic implications for the treatment of depressed suicide attempters, many of whom are affected by impulsive aggression.

Mouse and Human Genetic Analyses Associate Kalirin with Ventral Striatal Activation during Impulsivity and with Alcohol Misuse

PubMed Central

Peña-Oliver, Yolanda; Carvalho, Fabiana M.; Sanchez-Roige, Sandra; Quinlan, Erin B.; Jia, Tianye; Walker-Tilley, Tom; Rulten, Stuart L.; Pearl, Frances M. G.; Banaschewski, Tobias; Barker, Gareth J.; Bokde, Arun L. W.; Büchel, Christian; Conrod, Patricia J.; Flor, Herta; Gallinat, Jürgen; Garavan, Hugh; Heinz, Andreas; Gowland, Penny; Paillere Martinot, Marie-Laure; Paus, Tomáš; Rietschel, Marcella; Robbins, Trevor W.; Smolka, Michael N.; Schumann, Gunter; Stephens, David N.

2016-01-01

Impulsivity is associated with a spectrum of psychiatric disorders including drug addiction. To investigate genetic associations with impulsivity and initiation of drug taking, we took a two-step approach. First, we identified genes whose expression level in prefrontal cortex, striatum and accumbens were associated with impulsive behavior in the 5-choice serial reaction time task across 10 BXD recombinant inbred (BXD RI) mouse strains and their progenitor C57BL/6J and DBA2/J strains. Behavioral data were correlated with regional gene expression using GeneNetwork (www.genenetwork.org), to identify 44 genes whose probability of association with impulsivity exceeded a false discovery rate of < 0.05. We then interrogated the IMAGEN database of 1423 adolescents for potential associations of SNPs in human homologs of those genes identified in the mouse study, with brain activation during impulsive performance in the Monetary Incentive Delay task, and with novelty seeking scores from the Temperament and Character Inventory, as well as alcohol experience. There was a significant overall association between the human homologs of impulsivity-related genes and percentage of premature responses in the MID task and with fMRI BOLD-response in ventral striatum (VS) during reward anticipation. In contrast, no significant association was found between the polygenic scores and anterior cingulate cortex activation. Univariate association analyses revealed that the G allele (major) of the intronic SNP rs6438839 in the KALRN gene was significantly associated with increased VS activation. Additionally, the A-allele (minor) of KALRN intronic SNP rs4634050, belonging to the same haplotype block, was associated with increased frequency of binge drinking. PMID:27092175

Impulsive Aggression, Delay Discounting, and Adolescent Suicide Attempts: Effects of Current Psychotropic Medication Use and Family History of Suicidal Behavior

PubMed Central

Reynolds, Brady; McBee-Strayer, Sandra M.; Sheftall, Arielle H.; Ackerman, John; Stevens, Jack; Mendoza, Kristen; Campo, John V.; Brent, David A.

2015-01-01

Abstract Objective: Impulsive-aggressive behaviors have been consistently implicated in the phenomenology, neurobiology, and familial aggregation of suicidal behavior. The purpose of this study was to extend previous work by examining laboratory behavioral measures of delayed reward impulsivity and impulsive aggression in adolescent suicide attempters and never-suicidal comparison subjects. Methods: Using the Point Subtraction Aggression Paradigm (PSAP) and the Delay Discounting Task (DDQ), the authors examined delay discounting and impulsive aggression in 40 adolescent suicide attempters, ages 13–18, and 40 never-suicidal, demographically matched psychiatric comparison subjects. Results: Overall, suicide attempters and comparison subjects performed similarly on the PSAP and DDQ. There was a significant group by current psychotropic medication use interaction (p=0.013) for mean aggressive responses on the PSAP. Group comparisons revealed that attempters emitted more aggressive responses per provocation than comparison subjects, only in those not on psychotropic medication (p=0.049), whereas for those currently treated with psychotropic medication, there were no group differences (p>0.05). This interaction effect was specific to current antidepressant use. Among all subjects, family history of suicidal behavior (suicide or suicide attempt) in first degree relatives was significantly correlated with both delay discounting (r=−0.22, p=0.049), and aggressive responding (r=0.27, p=0.015). Family history of suicidal behavior was associated with delay discounting, but not with aggressive responding on the PSAP, after controlling for relevant covariates. Conclusions: In this study, impulsive-aggressive responding was associated with suicide attempt only in those not being treated with antidepressants. Future work to replicate and extend these findings could have important therapeutic implications for the treatment of depressed suicide attempters, many of whom are affected by impulsive aggression. PMID:25745870

Self-reported impulsivity, but not behavioral approach or inhibition, mediates the relationship between stress and self-control

PubMed Central

Hamilton, Kristen R.; Sinha, Rajita; Potenza, Marc N.

2014-01-01

Stress has been associated with poor self-control. Individual differences in impulsivity and other behavioral tendencies may influence the relationship of stress with self-control, although this possibility has not been examined to date. The present research investigated whether cumulative stress is associated with poor self-control, and whether this relationship is mediated by impulsivity, behavioral approach, and behavioral inhibition in men and women. A community sample of 566 adults (319 women and 247 men) was assessed on the Cumulative Adversity Interview, Brief Self-control Scale, Barratt Impulsivity Scale, and Behavioral Activation System and Behavioral Inhibition System Scale (BIS/BAS). Data were analyzed using regression and bootstrapping techniques. In the total sample, the effects of cumulative stress on self-control were mediated by impulsivity. Neither behavioral inhibition nor behavioral approach mediated the association between cumulative stress and self-control in the total sample. Results were similar when men and women were considered separately, with impulsivity, but not behavioral inhibition or approach, mediating the association between cumulative stress and self-control. Impulsive individuals might benefit preferentially from interventions focusing on stress management and strategies for improving self-control. PMID:24508183

Self-reported impulsivity, but not behavioral approach or inhibition, mediates the relationship between stress and self-control.

PubMed

Hamilton, Kristen R; Sinha, Rajita; Potenza, Marc N

2014-11-01

Stress has been associated with poor self-control. Individual differences in impulsivity and other behavioral tendencies may influence the relationship of stress with self-control, although this possibility has not been examined to date. The present research investigated whether cumulative stress is associated with poor self-control, and whether this relationship is mediated by impulsivity, behavioral approach, and behavioral inhibition in men and women. A community sample of 566 adults (319 women and 247 men) was assessed on the Cumulative Adversity Interview, Brief Self-control Scale, Barratt Impulsivity Scale, and Behavioral Activation System and Behavioral Inhibition System Scale (BIS/BAS). Data were analyzed using regression and bootstrapping techniques. In the total sample, the effects of cumulative stress on self-control were mediated by impulsivity. Neither behavioral inhibition nor behavioral approach mediated the association between cumulative stress and self-control in the total sample. Results were similar when men and women were considered separately, with impulsivity, but not behavioral inhibition or approach, mediating the association between cumulative stress and self-control. Impulsive individuals might benefit preferentially from interventions focusing on stress management and strategies for improving self-control. Copyright © 2014 Elsevier Ltd. All rights reserved.

Blocking serotonin but not dopamine reuptake alters neural processing during perceptual decision making.

PubMed

Costa, Vincent D; Kakalios, Laura C; Averbeck, Bruno B

2016-10-01

Dopamine and serotonin have opponent interactions on aspects of impulsivity. Therefore we wanted to test the hypothesis that dopamine and serotonin would have opposing effects on speed-accuracy trade offs in a perceptual decision making task. Unlike other behavioral measures of impulsivity, perceptual decision making allows us to determine whether decreasing premature responses, often interpreted as decreased impulsivity, corresponds to increased behavioral performance. We administered GBR-12909 (a dopamine transporter blocker), escitalopram (a serotonin transporter blocker), or saline in separate sessions to 3 rhesus macaques. We found that animals had slower reaction times (RTs) on escitalopram than on GBR-12909 or saline. However, they were also least accurate on escitalopram. Animals were faster, although nonsignificantly, on GBR than saline and had equivalent accuracy. Administration of GBR-12909 did cause animals to be faster in error trials than correct trials. Therefore, from the point of view of RTs the animals were less impulsive on escitalopram. However, the decreased accuracy of the monkeys shows that they were not able to make use of their slower response times to make more accurate decisions. Therefore, impulsivity was reduced on escitalopram, but at the expense of a slower information-processing rate in the perceptual inference task. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Primary reaction control system/remote manipulator system interaction with loaded arm. Space shuttle engineering and operations support

NASA Technical Reports Server (NTRS)

Taylor, E. C.; Davis, J. D.

1978-01-01

A study of the interaction between the orbiter primary reaction control system (PRCS) and the remote manipulator system (RMS) with a loaded arm is documented. This analysis was performed with the Payload Deployment and Retrieval Systems Simulation (PDRSS) program with the passive arm bending option. The passive-arm model simulates the arm as massless elastic links with locked joints. The study was divided into two parts. The first part was the evaluation of the response of the arm to step inputs (i.e. constant jet torques) about each of the orbiter body axes. The second part of the study was the evaluation of the response of the arm to minimum impulse primary RCS jet firings with both single pulse and pulse train inputs.

Cognitive control training for emotion-related impulsivity.

PubMed

Peckham, Andrew D; Johnson, Sheri L

2018-06-01

Many forms of psychopathology are tied to a heightened tendency to respond impulsively to strong emotions, and this tendency, in turn, is closely tied to problems with cognitive control. The goal of the present study was to test whether a two-week, six-session cognitive control training program is efficacious in reducing emotion-related impulsivity. Participants (N = 52) reporting elevated scores on an emotion-related impulsivity measure completed cognitive control training targeting working memory and response inhibition. A subset of participants were randomized to a waitlist control group. Impulsivity, emotion regulation, and performance on near and far-transfer cognitive tasks were assessed at baseline and after completion of training. Emotion-related impulsivity declined significantly from pre-training to post-training and at two-week follow-up; improvements were not observed in the waitlist control group. A decrease in brooding rumination and an increase in reappraisal were also observed. Participants showed significant improvements on trained versions of the working memory and inhibition tasks as well as improvements on an inhibition transfer task. In sum, these preliminary findings show that cognitive training appears to be well-tolerated for people with significant emotion-driven impulsivity. Results provide preliminary support for the efficacy of cognitive training interventions as a way to reduce emotion-related impulsivity. Copyright © 2018 Elsevier Ltd. All rights reserved.

Interrelationships among impulsive personality traits, food addiction, and Body Mass Index

PubMed Central

Murphy, Cara M.; Stojek, Monika K.; MacKillop, James

2016-01-01

Objective Impulsive personality traits have been robustly associated with alcohol and drug misuse, but have received little attention in the context of food addiction. The goal of the current study was to examine the interrelationships between impulsive personality traits, food addiction, and Body Mass Index (BMI), including indirect pathways of influence. Method Participants (N = 233) completed the Yale Food Addiction Scale (YFAS) to assess patterns of addictive consumption of food, the UPPS-P Impulsivity Scale to assess impulsive personality traits, and provided weight and height to generate BMI. Results Significant positive associations were found between facets of impulsivity, food addiction symptoms, and BMI. Impulsivity was found to be indirectly associated with BMI by way of associations with addictive consumption of food. In particular, an inclination toward behaving irrationally while experiencing negative mood states (Negative Urgency) and low levels of task persistence (lack of Perseverance) were significantly associated with food addiction directly and that relationship was responsible for their relationship to BMI. Conclusions Dispositional impulsivity, routinely associated with high-risk behaviors including addictive consumption of alcohol and drugs, may be an important risk factor when considering tendency to engage in addictive consumption of food. Monitoring food addiction symptoms early may help reduce the likelihood that compulsive food consumption patterns result in weight gain and obesity. Methodological considerations are discussed. PMID:24511618

Interrelationships among impulsive personality traits, food addiction, and Body Mass Index.

PubMed

Murphy, Cara M; Stojek, Monika K; MacKillop, James

2014-02-01

Impulsive personality traits have been robustly associated with alcohol and drug misuse, but have received little attention in the context of food addiction. The goal of the current study was to examine the interrelationships between impulsive personality traits, food addiction, and Body Mass Index (BMI), including indirect pathways of influence. Participants (N = 233) completed the Yale Food Addiction Scale (YFAS) to assess patterns of addictive consumption of food, the upps-p impulsivity scale to assess impulsive personality traits, and provided weight and height to generate BMI. Significant positive associations were found between facets of impulsivity, food addiction symptoms, and BMI. Impulsivity was found to be indirectly associated with BMI by way of associations with addictive consumption of food. In particular, an inclination toward behaving irrationally while experiencing negative mood states (Negative Urgency) and low levels of task persistence (lack of Perseverance) were significantly associated with food addiction directly and that relationship was responsible for their relationship to BMI. Dispositional impulsivity, routinely associated with high-risk behaviors including addictive consumption of alcohol and drugs, may be an important risk factor when considering tendency to engage in addictive consumption of food. Monitoring food addiction symptoms early may help reduce the likelihood that compulsive food consumption patterns result in weight gain and obesity. Methodological considerations are discussed.

The overlapping brain region accounting for the relationship between procrastination and impulsivity: A voxel-based morphometry study.

PubMed

Liu, Peiwei; Feng, Tingyong

2017-09-30

Procrastination is a prevalent problematic behavior that brings serious consequences, such as lower levels of health, wealth, and well-being. Previous research has verified that impulsivity is one of the traits most strongly correlated with procrastination. However, little is known about why there is a tight behavioral relationship between them. To address this question, we used voxel-based morphometry (VBM) to explore the common neural substrates between procrastination and impulsivity. In line with previous findings, the behavioral results showed a strong behavioral correlation between procrastination and impulsivity. Neuroimaging results showed impulsivity and procrastination shared the common neurobiological underpinnings in the dorsolateral prefrontal cortex (DLPFC) based on the data from 85 participants (sample 1). Furthermore, the mediation analysis revealed that impulsivity mediated the impact of gray matter (GM) volumes of this overlapping region in the DLPFC on procrastination on another independent 84 participants' data (sample 2). In conclusion, the overlapping brain region in the DLPFC would be responsible for the close relationship between procrastination and impulsivity. As a whole, the present study extends our knowledge on procrastination, and provides a novel perspective to explain the tight impulsivity - procrastination relationship. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Shift-variant linear system modeling for multispectral scanners

NASA Astrophysics Data System (ADS)

Amini, Abolfazl M.; Ioup, George E.; Ioup, Juliette W.

1995-07-01

Multispectral scanner data are affected both by the spatial impulse response of the sensor and the spectral response of each channel. To achieve a realistic representation for the output data for a given scene spectral input, both of these effects must be incorporated into a forward model. Each channel can have a different spatial response and each has its characteristic spectral response. A forward model is built which includes the shift invariant spatial broadening of the input for the channels and the shift variant spectral response across channels. The model is applied to the calibrated airborne multispectral scanner as well as the airborne terrestrial applications sensor developed at NASA Stennis Space Center.

JPRS Report Science & Technology Japan 16th International Congress of the International Society for Photogrammetry and Remote Sensing Volume 1

DTIC Science & Technology

1989-01-24

coherent noise . To overcome this disadvantages, a new holographic inverse filtering system has been developed by the authors. The inverse filter is...beam is blocked. The deblurred aerial image is formed in the image plane IP (the back focal plane of L2). The frequency of the grating used in this... impulse response of the optical system. For certain types of blurs, which include linear motion of the camera under the assumption that the picture

Operational calm and the optimum regulation of human working capacity

NASA Technical Reports Server (NTRS)

Ilin, Y. P.

1975-01-01

Muscle hardness measurements in a squeezing dynamometer test are interpreted for expressions of adjustment effects of the central nervous system in rapid response to a starting signal. It is shown that preliminary muscle tension leads to the transmission of inhibiting proprioceptive impulses to the nervous system centers and that the degree of pre-working changes depends on the individual's typological personality characteristics. Concentration of attention during the pre-working adjustment is considered the primary emotional factor that controls sensorimotor performance.

Impulsive control of a financial model [rapid communication

NASA Astrophysics Data System (ADS)

Sun, Jitao; Qiao, Fei; Wu, Qidi

2005-02-01

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

Identification of Scattering Mechanisms from Measured Impulse Response Signatures of Several Conducting Objects.

DTIC Science & Technology

1984-02-01

conducting sphere 35 compared to inverse transform of exact solution. 4-5. Measured impulse response of a conducting 2:1 right 37 circular cylinder with...frequency domain. This is equivalent to multiplication in the time domain by the inverse transform of w(n), which is shown in Figure 3-1 for N=15. The...equivalent pulse width from 0.066 T for the rectangular window to 0.10 T for the Hanning window. The inverse transform of the Hanning window is shown

Iterative design of one- and two-dimensional FIR digital filters. [Finite duration Impulse Response

NASA Technical Reports Server (NTRS)

Suk, M.; Choi, K.; Algazi, V. R.

1976-01-01

The paper describes a new iterative technique for designing FIR (finite duration impulse response) digital filters using a frequency weighted least squares approximation. The technique is as easy to implement (via FFT) and as effective in two dimensions as in one dimension, and there are virtually no limitations on the class of filter frequency spectra approximated. An adaptive adjustment of the frequency weight to achieve other types of design approximation such as Chebyshev type design is discussed.

Impulse oscillometry in the evaluation of diseases of the airways in children

PubMed Central

Komarow, Hirsh D.; Myles, Ian A.; Uzzaman, Ashraf; Metcalfe, Dean D.

2012-01-01

Objective To provide an overview of impulse oscillometry and its application to the evaluation of children with diseases of the airways. Data Sources Medline and PubMed search, limited to English language and human disease, with keywords forced oscillation, impulse oscillometry, and asthma. Study Selections The opinions of the authors were used to select studies for inclusion in this review. Results Impulse oscillometry is a noninvasive and rapid technique requiring only passive cooperation by the patient. Pressure oscillations are applied at the mouth to measure pulmonary resistance and reactance. It is employed by health care professionals to help diagnose pediatric pulmonary diseases such asthma and cystic fibrosis; assess therapeutic responses; and measure airway resistance during provocation testing. Conclusions Impulse oscillometry provides a rapid, noninvasive measure of airway impedance. It may be easily employed in the diagnosis and management of diseases of the airways in children. PMID:21354020

[Impulsivity-focused Group Intervention to reduce Binge Eating Episodes in Patients with Binge Eating Disorder - A Group Training Program].

PubMed

Schag, Kathrin; Leehr, Elisabeth J; Skoda, Eva-Maria; Becker, Sandra; Zipfel, Stephan; Giel, Katrin E

2016-11-01

Binge Eating Disorder (BED) is an eating disorder where cognitive behavioural therapy (CBT) could already show reliable efficacy. Relying on basic research, CBT interventions which especially focus on impulsivity could be effective, because binge eating episodes represent highly impulsive eating behaviour. For this reason, we developed a treatment concept about an impulsivity-focused behavioural group intervention for patients with BED, called IMPULS. The efficacy of IMPULS is currently investigated in a randomised controlled trial 1. IMPULS is drafted as a weekly group training programme with 5-6 participants per group. The essential interventions are food-related cue exposure with response prevention and the development of self-control strategies. These interventions are adapted onto the impulsivity concept from conventional treatment of addictive disorders and BED. © Georg Thieme Verlag KG Stuttgart · New York.

Theoretical analysis of the electrical aspects of the basic electro-impulse problem in aircraft de-icing applications

NASA Technical Reports Server (NTRS)

Henderson, R. A.; Schrag, R. L.

1986-01-01

A summary of modeling the electrical system aspects of a coil and metal target configuration resembling a practical electro-impulse deicing (EIDI) installation, and a simple circuit for providing energy to the coil, was presented. The model was developed in sufficient theoretical detail to allow the generation of computer algorithms for the current in the coil, the magnetic induction on both surfaces of the target, the force between the coil and target, and the impulse delivered to the target. These algorithms were applied to a specific prototype EIDI test system for which the current, magnetic fields near the target surfaces, and impulse were previously measured.

Adaptive infinite impulse response system identification using modified-interior search algorithm with Lèvy flight.

PubMed

Kumar, Manjeet; Rawat, Tarun Kumar; Aggarwal, Apoorva

2017-03-01

In this paper, a new meta-heuristic optimization technique, called interior search algorithm (ISA) with Lèvy flight is proposed and applied to determine the optimal parameters of an unknown infinite impulse response (IIR) system for the system identification problem. ISA is based on aesthetics, which is commonly used in interior design and decoration processes. In ISA, composition phase and mirror phase are applied for addressing the nonlinear and multimodal system identification problems. System identification using modified-ISA (M-ISA) based method involves faster convergence, single parameter tuning and does not require derivative information because it uses a stochastic random search using the concepts of Lèvy flight. A proper tuning of control parameter has been performed in order to achieve a balance between intensification and diversification phases. In order to evaluate the performance of the proposed method, mean square error (MSE), computation time and percentage improvement are considered as the performance measure. To validate the performance of M-ISA based method, simulations has been carried out for three benchmarked IIR systems using same order and reduced order system. Genetic algorithm (GA), particle swarm optimization (PSO), cat swarm optimization (CSO), cuckoo search algorithm (CSA), differential evolution using wavelet mutation (DEWM), firefly algorithm (FFA), craziness based particle swarm optimization (CRPSO), harmony search (HS) algorithm, opposition based harmony search (OHS) algorithm, hybrid particle swarm optimization-gravitational search algorithm (HPSO-GSA) and ISA are also used to model the same examples and simulation results are compared. Obtained results confirm the efficiency of the proposed method. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

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.

Improving control over the impulse for reward: sensitivity of harmful alcohol drinkers to delayed reward but not immediate punishment.

PubMed

Rossiter, Sarah; Thompson, Julian; Hester, Robert

2012-09-01

Cognitive control dysfunction has been identified in dependent alcohol users and implicated in the transition from abuse to dependence, although evidence of dyscontrol in chronic but non-dependent 'harmful' alcohol abusers is mixed. The current study examined harmful alcohol users response inhibition over rewarding stimuli in the presence of monetary reward and punishment, to determine whether changes in sensitivity to these factors, noted in imaging studies of dependent users, influences impulse control. Harmful (n=30) and non-hazardous (n=55) alcohol users were administered a Monetary Incentive Go/No-go task that required participants to inhibit a prepotent motor response associated with reward. Harmful alcohol users showed a significantly poorer ability to withhold their impulse for a rewarding stimulus in the presence of immediate monetary punishment for failure, while retaining equivalent response inhibition performance under neutral conditions (associated with neither monetary loss or gain), and significantly better performance under delayed reward conditions. The results of the present study suggest that non-dependent alcohol abusers have altered sensitivity to reward and punishment that influences their impulse control for reward, in the absence of gross dyscontrol that is consistent with past findings in which such performance contingencies were not used. The ability of delayed monetary reward, but not punishment, to increase sustained impulse control in this sample has implications for the mechanism that might underlie the transition from alcohol abuse to dependence, as well as intervention strategies aimed at preventing this transition. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Frequency Domain Analysis of Narx Neural Networks

NASA Astrophysics Data System (ADS)

Chance, J. E.; Worden, K.; Tomlinson, G. R.

1998-06-01

A method is proposed for interpreting the behaviour of NARX neural networks. The correspondence between time-delay neural networks and Volterra series is extended to the NARX class of networks. The Volterra kernels, or rather, their Fourier transforms, are obtained via harmonic probing. In the same way that the Volterra kernels generalize the impulse response to non-linear systems, the Volterra kernel transforms can be viewed as higher-order analogues of the Frequency Response Functions commonly used in Engineering dynamics; they can be interpreted in much the same way.

Behavioral Assessment of Impulsivity: A Comparison of Children with and without Attention Deficit Hyperactivity Disorder

ERIC Educational Resources Information Center

Neef, Nancy A.; Marckel, Julie; Ferreri, Summer J.; Bicard, David F.; Endo, Sayaka; Aman, Michael G.; Miller, Kelly M.; Jung, Sunhwa; Nist, Lindsay; Armstrong, Nancy

2005-01-01

We conducted a brief computer-based assessment involving choices of concurrently presented arithmetic problems associated with competing reinforcer dimensions to assess impulsivity (choices controlled primarily by reinforcer immediacy) as well as the relative influence of other dimensions (reinforcer rate, quality, and response effort), with 58…

An OFDM Receiver with Frequency Domain Diversity Combined Impulsive Noise Canceller for Underwater Network.

PubMed

Saotome, Rie; Hai, Tran Minh; Matsuda, Yasuto; Suzuki, Taisaku; Wada, Tomohisa

2015-01-01

In order to explore marine natural resources using remote robotic sensor or to enable rapid information exchange between ROV (remotely operated vehicles), AUV (autonomous underwater vehicle), divers, and ships, ultrasonic underwater communication systems are used. However, if the communication system is applied to rich living creature marine environment such as shallow sea, it suffers from generated Impulsive Noise so-called Shrimp Noise, which is randomly generated in time domain and seriously degrades communication performance in underwater acoustic network. With the purpose of supporting high performance underwater communication, a robust digital communication method for Impulsive Noise environments is necessary. In this paper, we propose OFDM ultrasonic communication system with diversity receiver. The main feature of the receiver is a newly proposed Frequency Domain Diversity Combined Impulsive Noise Canceller. The OFDM receiver utilizes 20-28 KHz ultrasonic channel and subcarrier spacing of 46.875 Hz (MODE3) and 93.750 Hz (MODE2) OFDM modulations. In addition, the paper shows Impulsive Noise distribution data measured at a fishing port in Okinawa and at a barge in Shizuoka prefectures and then proposed diversity OFDM transceivers architecture and experimental results are described. By the proposed Impulsive Noise Canceller, frame bit error rate has been decreased by 20-30%.

INDIVIDUAL DIFFERENCES IN IMPULSIVE CHOICE AND TIMING IN RATS

PubMed Central

Galtress, Tiffany; Garcia, Ana; Kirkpatrick, Kimberly

2012-01-01

Individual differences in impulsive choice behavior have been linked to a variety of behavioral problems including substance abuse, smoking, gambling, and poor financial decision-making. Given the potential importance of individual differences in impulsive choice as a predictor of behavioral problems, the present study sought to measure the extent of individual differences in a normal sample of hooded Lister rats. Three experiments utilized variations of a delay discounting task to measure the degree of variation in impulsive choice behavior across individual rats. The individual differences accounted for 22–55% of the variance in choice behavior across the three experiments. In Experiments 2 and 3, the individual differences were still apparent when behavior was measured across multiple choice points. Large individual differences in the rate of responding, and modest individual differences in timing of responding were also observed during occasional peak trials. The individual differences in timing and rate, however, did not correlate consistently with individual differences in choice behavior. This suggests that a variety of factors may affect choice behavior, response rate, and response timing. PMID:22851792

Minimal Time Problem with Impulsive Controls

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

Kunisch, Karl, E-mail: karl.kunisch@uni-graz.at; Rao, Zhiping, E-mail: zhiping.rao@ricam.oeaw.ac.at

Time optimal control problems for systems with impulsive controls are investigated. Sufficient conditions for the existence of time optimal controls are given. A dynamical programming principle is derived and Lipschitz continuity of an appropriately defined value functional is established. The value functional satisfies a Hamilton–Jacobi–Bellman equation in the viscosity sense. A numerical example for a rider-swing system is presented and it is shown that the reachable set is enlargered by allowing for impulsive controls, when compared to nonimpulsive controls.

Investigation of Blade Impulsive Noise on a Scaled Fully Articulated Rotor System

NASA Technical Reports Server (NTRS)

Scheiman, James; Hoad, Danny R.

1977-01-01

Helicopter impulsive noise tests were conducted in the Langley V/STOL tunnel with an articulated rotor system. The tests demonstrated that impulsive noise could be simulated for low-speed forward flight with low descent rates and also in the high-speed level flight. For the low forward speed condition, the noise level was highly sensitive to small changes in descent rate. For the high-speed condition, the noise level was increased with an increase in rotor thrust.

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.

Detecting Structural Failures Via Acoustic Impulse Responses

NASA Technical Reports Server (NTRS)

Bayard, David S.; Joshi, Sanjay S.

1995-01-01

Advanced method of acoustic pulse reflectivity testing developed for use in determining sizes and locations of failures within structures. Used to detect breaks in electrical transmission lines, detect faults in optical fibers, and determine mechanical properties of materials. In method, structure vibrationally excited with acoustic pulse (a "ping") at one location and acoustic response measured at same or different location. Measured acoustic response digitized, then processed by finite-impulse-response (FIR) filtering algorithm unique to method and based on acoustic-wave-propagation and -reflection properties of structure. Offers several advantages: does not require training, does not require prior knowledge of mathematical model of acoustic response of structure, enables detection and localization of multiple failures, and yields data on extent of damage at each location.

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.

Climatic and land-use driven change of runoff throughout Sweden

NASA Astrophysics Data System (ADS)

Worman, A. L. E.; Riml, J.; Lindstrom, G.

2015-12-01

Changes in runoff can be caused by climatic variations, land-use changes and water regulation. In this paper we propose a separation of the power spectral response of runoff in watersheds in terms of the product of the power spectra of precipitation and the impulse response function for the watershed. This allows a formal separation of the spectral response in climatic factors - the precipitation - from those of land-use change and regulation - the impulse response function. The latter function characterizes the surface water-groundwater interaction, stream network topology and open channel hydraulics. Based on daily data of digitalized hydro-climatological data from 1961, we constructed synthetic, but calibrated data of runoff from 1001 watersheds in Sweden. From spectral analysis of the data we found periodic fluctuations occurring on time scales of about a decade and a bi-annual peak. These multi-annual fluctuations could be statistically linked through the coherence spectra to climatic indices like the NAO, PDO, geostrophic wind velocity and sun spot numbers on common periods of 3,6 and 7,6 years. Such long-term fluctuations in runoff are not significantly affected by the land-use or regulation other than indirectly through impact on local hydro-climate. Based on a spectral separation of precipitation and impulse response function of the watersheds, we found that the intra-annual variation in runoff was primarily affected by the land-use change in 79 unregulated catchments with up to century-long time series of measured daily discharge. There is a statistically significant increasing slope of the catchments impulse response function for 63 of the 79 catchments and this suggest a significant hydrological effect of land-use practice in agriculture, urbanisation and forestry.

Reduced attention and increased impulsivity in mice lacking NPY Y2 receptors: relation to anxiolytic-like phenotype.

PubMed

Greco, Barbara; Carli, Mirjana

2006-05-15

Neuropeptide (NPY) Y2 receptors play an important role in some anxiety-related and stress-related behaviours in mice. Changes in the level of anxiety can affect some cognitive functions such as memory, attention and inhibitory response control. We investigated the effects of NPY Y2 receptor deletion (Y2(-/-)) in mice on visual attention and response control using the five-choice serial reaction time (5-CSRT) task in which accuracy of detection of a brief visual stimulus across five spatial locations may serve as a valid behavioural index of attentional functioning. Anticipatory and perseverative responses provide a measure of inhibitory response control. During training, the Y2(-/-) mice had lower accuracy (% correct), and made more anticipatory responses. At stimulus durations of 2 and 4s the Y2(-/-) were as accurate as the Y2(+/+) mice but still more impulsive than Y(+/+). At stimulus durations of 0.25 and 0.5s both groups performed worse but the Y2(-/-) mice made significantly fewer correct responses than the Y2(+/+) controls. The anxiolytic drug diazepam at 2mg/kg IP greatly increased the anticipatory responding of Y2(-/-) mice compared to Y2(+/+). The anxiogenic inverse benzodiazepine agonist, FG 7142, at 10mg/kg IP reduced the anticipatory responding of Y2(-/-) but not Y2(+/+) mice. These data suggest that NPY Y2 receptors make an important contribution to mechanisms controlling attentional functioning and "impulsivity". They also show that "impulsivity" of NPY Y2(-/-) mice may depend on their level of anxiety. These findings may help in understanding the pathophysiology of stress disorders and depression.

33 CFR 183.586 - Pressure impulse test.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.586 Pressure impulse test. A fuel... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Pressure impulse test. 183.586... pressure test under § 183.580. (b) If the tank is non-metallic, fill it to capacity with a gasoline that...

33 CFR 183.586 - Pressure impulse test.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.586 Pressure impulse test. A fuel... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Pressure impulse test. 183.586... pressure test under § 183.580. (b) If the tank is non-metallic, fill it to capacity with a gasoline that...

33 CFR 183.586 - Pressure impulse test.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.586 Pressure impulse test. A fuel... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Pressure impulse test. 183.586... pressure test under § 183.580. (b) If the tank is non-metallic, fill it to capacity with a gasoline that...

33 CFR 183.586 - Pressure impulse test.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.586 Pressure impulse test. A fuel... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Pressure impulse test. 183.586... pressure test under § 183.580. (b) If the tank is non-metallic, fill it to capacity with a gasoline that...

33 CFR 183.586 - Pressure impulse test.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.586 Pressure impulse test. A fuel... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Pressure impulse test. 183.586... pressure test under § 183.580. (b) If the tank is non-metallic, fill it to capacity with a gasoline that...

Decoupling analysis for a powertrain mounting system with a combination of hydraulic mounts

NASA Astrophysics Data System (ADS)

Hu, Jinfang; Chen, Wuwei; Huang, He

2013-07-01

The existing torque roll axis(TRA) decoupling theories for a powertrain mounting system assume that the stiffness and viscous damping properties are constant. However, real-life mounts exhibit considerable spectrally varying stiffness and damping characteristics, and the influence of the spectrally-varying properties of the hydraulic mounts on the powertrain system cannot be ignored. To overcome the deficiency, an analytical quasi-linear model of the hydraulic mount and the coupled properties of the powertrain and hydraulic mounts system are formulated. The influence of the hydraulic mounts on the TRA decoupling of a powertrain system is analytically examined in terms of eigensolutions, frequency, and impulse responses, and then a new analytical axiom is proposed based on the TRA decoupling indices. With the experimental setup of a fixed decoupler hydraulic mount in the context of non-resonant dynamic stiffness testing procedure, the quasi-linear model of the hydraulic mount is verified by comparing the predictions with the measurement. And the quasi-linear formulation of the coupled system is also verified by comparing the frequency responses with the numerical results obtained by the direct inversion method. Finally, the mounting system with a combination of hydraulic mounts is redesigned in terms of the stiffness, damping and mount locations by satisfying the new axiom. The frequency and time domain results of the redesigned system demonstrate that the torque roll axis of the redesigned powertrain mounting system is indeed decoupled in the presence of hydraulic mounts (given oscillating torque or impulsive torque excitation). The proposed research provides an important basis and method for the research on a powertrain system with spectrally-varying mount properties, especially for the TRA decoupling.

Method and system for training dynamic nonlinear adaptive filters which have embedded memory

NASA Technical Reports Server (NTRS)

Rabinowitz, Matthew (Inventor)

2002-01-01

Described herein is a method and system for training nonlinear adaptive filters (or neural networks) which have embedded memory. Such memory can arise in a multi-layer finite impulse response (FIR) architecture, or an infinite impulse response (IIR) architecture. We focus on filter architectures with separate linear dynamic components and static nonlinear components. Such filters can be structured so as to restrict their degrees of computational freedom based on a priori knowledge about the dynamic operation to be emulated. The method is detailed for an FIR architecture which consists of linear FIR filters together with nonlinear generalized single layer subnets. For the IIR case, we extend the methodology to a general nonlinear architecture which uses feedback. For these dynamic architectures, we describe how one can apply optimization techniques which make updates closer to the Newton direction than those of a steepest descent method, such as backpropagation. We detail a novel adaptive modified Gauss-Newton optimization technique, which uses an adaptive learning rate to determine both the magnitude and direction of update steps. For a wide range of adaptive filtering applications, the new training algorithm converges faster and to a smaller value of cost than both steepest-descent methods such as backpropagation-through-time, and standard quasi-Newton methods. We apply the algorithm to modeling the inverse of a nonlinear dynamic tracking system 5, as well as a nonlinear amplifier 6.

Bias effects on the electronic spectrum of a molecular bridge

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

Phillips, Heidi; Prociuk, Alexander; Dunietz, Barry D

2011-01-01

In this paper the effect of bias and geometric symmetry breaking on the electronic spectrum of a model molecular system is studied. Geometric symmetry breaking can either enhance the dissipative effect of the bias, where spectral peaks are disabled, or enable new excitations that are absent under zero bias conditions. The spectralanalysis is performed on a simple model system by solving for the electronic response to an instantaneously impulsive perturbation in the dipole approximation. The dynamical response is extracted from the electronic equations of motion as expressed by the Keldysh formalism. This expression provides for the accurate treatment of themore » electronic structure of a bulk-coupled system at the chosen model Hamiltonian electronic structure level.« less

Validity of DSM-IV attention deficit/hyperactivity disorder symptom dimensions and subtypes.

PubMed

Willcutt, Erik G; Nigg, Joel T; Pennington, Bruce F; Solanto, Mary V; Rohde, Luis A; Tannock, Rosemary; Loo, Sandra K; Carlson, Caryn L; McBurnett, Keith; Lahey, Benjamin B

2012-11-01

Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) criteria for attention deficit/hyperactivity disorder (ADHD) specify two dimensions of inattention and hyperactivity-impulsivity symptoms that are used to define three nominal subtypes: predominantly hyperactive-impulsive type (ADHD-H), predominantly inattentive type (ADHD-I), and combined type (ADHD-C). To aid decision making for DSM-5 and other future diagnostic systems, a comprehensive literature review and meta-analysis of 546 studies was completed to evaluate the validity of the DSM-IV model of ADHD. Results indicated that DSM-IV criteria identify individuals with significant and persistent impairment in social, academic, occupational, and adaptive functioning when intelligence, demographic factors, and concurrent psychopathology are controlled. Available data overwhelmingly support the concurrent, predictive, and discriminant validity of the distinction between inattention and hyperactivity-impulsivity symptoms, and indicate that nearly all differences among the nominal subtypes are consistent with the relative levels of inattention and hyperactivity-impulsivity symptoms that define the subtypes. In contrast, the DSM-IV subtype model is compromised by weak evidence for the validity of ADHD-H after first grade, minimal support for the distinction between ADHD-I and ADHD-C in studies of etiological influences, academic and cognitive functioning, and treatment response, and the marked longitudinal instability of all three subtypes. Overall, we conclude that the DSM-IV ADHD subtypes provide a convenient clinical shorthand to describe the functional and behavioral correlates of current levels of inattention and hyperactivity-impulsivity symptoms, but do not identify discrete subgroups with sufficient long-term stability to justify the classification of distinct forms of the disorder. Empirical support is stronger for an alternative model that would replace the subtypes with dimensional modifiers that reflect the number of inattention and hyperactivity-impulsivity symptoms at the time of assessment. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

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

Extension of a nonlinear systems theory to general-frequency unsteady transonic aerodynamic responses

NASA Technical Reports Server (NTRS)

Silva, Walter A.

1993-01-01

A methodology for modeling nonlinear unsteady aerodynamic responses, for subsequent use in aeroservoelastic analysis and design, using the Volterra-Wiener theory of nonlinear systems is presented. The methodology is extended to predict nonlinear unsteady aerodynamic responses of arbitrary frequency. The Volterra-Wiener theory uses multidimensional convolution integrals to predict the response of nonlinear systems to arbitrary inputs. The CAP-TSD (Computational Aeroelasticity Program - Transonic Small Disturbance) code is used to generate linear and nonlinear unit impulse responses that correspond to each of the integrals for a rectangular wing with a NACA 0012 section with pitch and plunge degrees of freedom. The computed kernels then are used to predict linear and nonlinear unsteady aerodynamic responses via convolution and compared to responses obtained using the CAP-TSD code directly. The results indicate that the approach can be used to predict linear unsteady aerodynamic responses exactly for any input amplitude or frequency at a significant cost savings. Convolution of the nonlinear terms results in nonlinear unsteady aerodynamic responses that compare reasonably well with those computed using the CAP-TSD code directly but at significant computational cost savings.

Global dynamics of a stochastic neuronal oscillator

NASA Astrophysics Data System (ADS)

Yamanobe, Takanobu

2013-11-01

Nonlinear oscillators have been used to model neurons that fire periodically in the absence of input. These oscillators, which are called neuronal oscillators, share some common response structures with other biological oscillations such as cardiac cells. In this study, we analyze the dependence of the global dynamics of an impulse-driven stochastic neuronal oscillator on the relaxation rate to the limit cycle, the strength of the intrinsic noise, and the impulsive input parameters. To do this, we use a Markov operator that both reflects the density evolution of the oscillator and is an extension of the phase transition curve, which describes the phase shift due to a single isolated impulse. Previously, we derived the Markov operator for the finite relaxation rate that describes the dynamics of the entire phase plane. Here, we construct a Markov operator for the infinite relaxation rate that describes the stochastic dynamics restricted to the limit cycle. In both cases, the response of the stochastic neuronal oscillator to time-varying impulses is described by a product of Markov operators. Furthermore, we calculate the number of spikes between two consecutive impulses to relate the dynamics of the oscillator to the number of spikes per unit time and the interspike interval density. Specifically, we analyze the dynamics of the number of spikes per unit time based on the properties of the Markov operators. Each Markov operator can be decomposed into stationary and transient components based on the properties of the eigenvalues and eigenfunctions. This allows us to evaluate the difference in the number of spikes per unit time between the stationary and transient responses of the oscillator, which we show to be based on the dependence of the oscillator on past activity. Our analysis shows how the duration of the past neuronal activity depends on the relaxation rate, the noise strength, and the impulsive input parameters.

Global dynamics of a stochastic neuronal oscillator.

PubMed

Yamanobe, Takanobu

2013-11-01

Nonlinear oscillators have been used to model neurons that fire periodically in the absence of input. These oscillators, which are called neuronal oscillators, share some common response structures with other biological oscillations such as cardiac cells. In this study, we analyze the dependence of the global dynamics of an impulse-driven stochastic neuronal oscillator on the relaxation rate to the limit cycle, the strength of the intrinsic noise, and the impulsive input parameters. To do this, we use a Markov operator that both reflects the density evolution of the oscillator and is an extension of the phase transition curve, which describes the phase shift due to a single isolated impulse. Previously, we derived the Markov operator for the finite relaxation rate that describes the dynamics of the entire phase plane. Here, we construct a Markov operator for the infinite relaxation rate that describes the stochastic dynamics restricted to the limit cycle. In both cases, the response of the stochastic neuronal oscillator to time-varying impulses is described by a product of Markov operators. Furthermore, we calculate the number of spikes between two consecutive impulses to relate the dynamics of the oscillator to the number of spikes per unit time and the interspike interval density. Specifically, we analyze the dynamics of the number of spikes per unit time based on the properties of the Markov operators. Each Markov operator can be decomposed into stationary and transient components based on the properties of the eigenvalues and eigenfunctions. This allows us to evaluate the difference in the number of spikes per unit time between the stationary and transient responses of the oscillator, which we show to be based on the dependence of the oscillator on past activity. Our analysis shows how the duration of the past neuronal activity depends on the relaxation rate, the noise strength, and the impulsive input parameters.

Frontal glutamate and reward processing in adolescence and adulthood.

PubMed

Gleich, Tobias; Lorenz, Robert C; Pöhland, Lydia; Raufelder, Diana; Deserno, Lorenz; Beck, Anne; Heinz, Andreas; Kühn, Simone; Gallinat, Jürgen

2015-11-01

The fronto-limbic network interaction, driven by glutamatergic and dopaminergic neurotransmission, represents a core mechanism of motivated behavior and personality traits. Reward seeking behavior undergoes tremendous changes in adolescence paralleled by neurobiological changes of this network including the prefrontal cortex, striatum and amygdala. Since fronto-limbic dysfunctions also underlie major psychiatric diseases beginning in adolescence, this investigation focuses on network characteristics separating adolescents from adults. To investigate differences in network interactions, the brain reward system activity (slot machine task) together with frontal glutamate concentration (anterior cingulate cortex, ACC) was measured in 28 adolescents and 26 adults employing functional magnetic resonance imaging and magnetic resonance spectroscopy, respectively. An inverse coupling of glutamate concentrations in the ACC and activation of the ventral striatum was observed in adolescents. Further, amygdala response in adolescents was negatively correlated with the personality trait impulsivity. For adults, no significant associations of network components or correlations with impulsivity were found. The inverse association between frontal glutamate concentration and striatal activation in adolescents is in line with the triadic model of motivated behavior stressing the important role of frontal top-down inhibition on limbic structures. Our data identified glutamate as the mediating neurotransmitter of this inhibitory process and demonstrates the relevance of glutamate on the reward system and related behavioral traits like impulsivity. This fronto-limbic coupling may represent a vulnerability factor for psychiatric disorders starting in adolescence but not in adulthood.

Impulse generation by detonation tubes

NASA Astrophysics Data System (ADS)

Cooper, Marcia Ann

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

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

Neuronal correlates of reward and loss in Cluster B personality disorders: a functional magnetic resonance imaging study.

PubMed

Völlm, Birgit; Richardson, Paul; McKie, Shane; Elliott, Rebecca; Dolan, Mairead; Deakin, Bill

2007-11-15

Decision making is guided by the likely consequences of behavioural choices. Neuronal correlates of financial reward have been described in a number of functional imaging studies in humans. Areas implicated in reward include ventral striatum, dopaminergic midbrain, amygdala and orbitofrontal cortex. Response to loss has not been as extensively studied but may involve prefrontal and medial temporal cortices. It has been proposed that increased sensitivity to reward and reduced sensitivity to punishment underlie some of the psychopathology in impulsive personality disordered individuals. However, few imaging studies using reinforcement tasks have been conducted in this group. In this fMRI study, we investigate the effects of positive (monetary reward) and negative (monetary loss) outcomes on BOLD responses in two target selection tasks. The experimental group comprised eight people with Cluster B (antisocial and borderline) personality disorder, whilst the control group contained fourteen healthy participants. A key finding was the absence of prefrontal responses and reduced BOLD signal in the subcortical reward system in the PD group during positive reinforcement. Impulsivity scores correlated negatively with prefrontal responses in the PD but not the control group during both, reward and loss. Our results suggest dysfunctional responses to rewarding and aversive stimuli in Cluster B personality disordered individuals but do not support the notion of hypersensitivity to reward and hyposensitivity to loss.

Impulsivity and Gambling Type Among Treatment-Seeking Disordered Gamblers: An Explorative Study.

PubMed

Lutri, Vittorio; Soldini, Emiliano; Ronzitti, Silvia; Smith, Neil; Clerici, Massimo; Blaszczynski, Alex; Bowden-Jones, Henrietta

2018-03-03

Several studies have found that certain traits of impulsivity are associated with gambling disorder, and influence its severity. Furthermore, it has been suggested that some forms of gambling, particularly electronic gambling machines, are particularly widespread among pathological gamblers. In the present, exploratory study, we aim to clarify the role played by impulsivity in influencing the choice of specific gambling activities, by examining the relation between individual dimensions of impulsivity, and the choice of specific gambling activities in a clinical population. 100 consecutively admitted pathological gamblers at the National Problem Gambling Clinic in London (UK) in 2014 were administered the UPPS-P and BIS-11 impulsivity questionnaires, the Problem Gambling Severity Index, and underwent a structured interview concerning their gambling activities in the month and year prior to assessment. The correlation between individual gambling activities and impulsivity dimensions was analyzed both at a bivariate level, and using logistic regression. We found a significant correlation between Negative Urgency, Motor impulsivity and low-stakes machine gambling on multivariate analysis. Negative urgency (i.e. the tendency to act impulsively in response to negative affect), and Motor impulsivity (a tendency to rash action and restlessness) might be mediating factors in the choice of electronic gambling machines, particularly among patients whose gambling is escape-oriented. Structural and situational characteristics of gambling machines, particularly the widespread availability of low-stakes-rather than high-stakes-gaming machines, might concur to the choice of this form of gambling among individuals who present higher negative urgency and restlessness.

Cued to Act on Impulse: More Impulsive Choice and Risky Decision Making by Women Susceptible to Overeating after Exposure to Food Stimuli.

PubMed

Yeomans, Martin R; Brace, Aaron

2015-01-01

There is increasing evidence that individual differences in tendency to overeat relate to impulsivity, possibly by increasing reactivity to food-related cues in the environment. This study tested whether acute exposure to food cues enhanced impulsive and risky responses in women classified on tendency to overeat, indexed by scores on the three factor eating questionnaire disinhibition (TFEQ-D), restraint (TFEQ-R) and hunger scales. Ninety six healthy women completed two measures of impulsive responding (delayed discounting, DDT and a Go No-Go, GNG, task) and a measure of risky decision making (the balloon analogue risk task, BART) as well as questionnaire measures of impulsive behaviour either after looking at a series of pictures of food or visually matched controls. Impulsivity (DDT) and risk-taking (BART) were both positively associated with TFEQ-D scores, but in both cases this effect was exacerbated by prior exposure to food cues. No effects of restraint were found. TFEQ-D scores were also related to more commission errors on the GNG, while restrained women were slower on the GNG, but neither effect was modified by cue exposure. Overall these data suggest that exposure to food cues act to enhance general impulsive responding in women at risk of overeating and tentatively suggest an important interaction between tendency for impulsive decision making and food cues that may help explain a key underlying risk factor for overeating.

Cued to Act on Impulse: More Impulsive Choice and Risky Decision Making by Women Susceptible to Overeating after Exposure to Food Stimuli

PubMed Central

Yeomans, Martin R.; Brace, Aaron

2015-01-01

There is increasing evidence that individual differences in tendency to overeat relate to impulsivity, possibly by increasing reactivity to food-related cues in the environment. This study tested whether acute exposure to food cues enhanced impulsive and risky responses in women classified on tendency to overeat, indexed by scores on the three factor eating questionnaire disinhibition (TFEQ-D), restraint (TFEQ-R) and hunger scales. Ninety six healthy women completed two measures of impulsive responding (delayed discounting, DDT and a Go No-Go, GNG, task) and a measure of risky decision making (the balloon analogue risk task, BART) as well as questionnaire measures of impulsive behaviour either after looking at a series of pictures of food or visually matched controls. Impulsivity (DDT) and risk-taking (BART) were both positively associated with TFEQ-D scores, but in both cases this effect was exacerbated by prior exposure to food cues. No effects of restraint were found. TFEQ-D scores were also related to more commission errors on the GNG, while restrained women were slower on the GNG, but neither effect was modified by cue exposure. Overall these data suggest that exposure to food cues act to enhance general impulsive responding in women at risk of overeating and tentatively suggest an important interaction between tendency for impulsive decision making and food cues that may help explain a key underlying risk factor for overeating. PMID:26378459

D4 receptor deficiency in mice has limited effects on impulsivity and novelty seeking.

PubMed

Helms, C M; Gubner, N R; Wilhelm, C J; Mitchell, S H; Grandy, D K

2008-09-01

Alleles of the human dopamine D(4) receptor (D(4)R) gene (DRD4.7) have repeatedly been found to correlate with novelty seeking, substance abuse, pathological gambling, and attention-deficit hyperactivity disorder (ADHD). If these various psychopathologies are a result of attenuated D(4)R-mediated signaling, mice lacking D(4)Rs (D(4)KO) should be more impulsive than wild-type (WT) mice and exhibit more novelty seeking. However, in our study, D(4)KO and WT mice showed similar levels of impulsivity as measured by delay discounting performance and response inhibition on a Go/No-go test, suggesting that D(4)R-mediated signaling may not affect impulsivity. D(4)KO mice were more active than WT mice in the first 5 min of a novel open field test, suggesting greater novelty seeking. For both genotypes, more impulsive mice habituated less in the novel open field. These data suggest that the absence of D(4)Rs is not sufficient to cause psychopathologies associated with heightened impulsivity and novelty seeking.

Preliminary evidence of altered neural response during intertemporal choice of losses in adult attention-deficit hyperactivity disorder.

PubMed

Tanaka, Saori C; Yahata, Noriaki; Todokoro, Ayako; Kawakubo, Yuki; Kano, Yukiko; Nishimura, Yukika; Ishii-Takahashi, Ayaka; Ohtake, Fumio; Kasai, Kiyoto

2018-04-30

Impulsive behaviours are common symptoms of attention-deficit hyperactivity disorder (ADHD). Although previous studies have suggested functional models of impulsive behaviour, a full explanation of impulsivity in ADHD remains elusive. To investigate the detailed mechanisms behind impulsive behaviour in ADHD, we applied an economic intertemporal choice task involving gains and losses to adults with ADHD and healthy controls and measured brain activity by functional magnetic resonance imaging. In the intertemporal choice of future gains, we observed no behavioural or neural difference between the two groups. In the intertemporal choice of future losses, adults with ADHD exhibited higher discount rates than the control participants. Furthermore, a comparison of brain activity representing the sensitivity of future loss in the two groups revealed significantly lower activity in the striatum and higher activity in the amygdala in adults with ADHD than in controls. Our preliminary findings suggest that an altered size sensitivity to future loss is involved in apparent impulsive choice behaviour in adults with ADHD and shed light on the multifaceted impulsivity underlying ADHD.

Robust exponential stability of uncertain delayed neural networks with stochastic perturbation and impulse effects.

PubMed

Huang, Tingwen; Li, Chuandong; Duan, Shukai; Starzyk, Janusz A

2012-06-01

This paper focuses on the hybrid effects of parameter uncertainty, stochastic perturbation, and impulses on global stability of delayed neural networks. By using the Ito formula, Lyapunov function, and Halanay inequality, we established several mean-square stability criteria from which we can estimate the feasible bounds of impulses, provided that parameter uncertainty and stochastic perturbations are well-constrained. Moreover, the present method can also be applied to general differential systems with stochastic perturbation and impulses.

Finite-time resilient decentralized control for interconnected impulsive switched systems with neutral delay.

PubMed

Ren, Hangli; Zong, Guangdeng; Hou, Linlin; Yang, Yi

2017-03-01

This paper is concerned with the problem of finite-time control for a class of interconnected impulsive switched systems with neutral delay in which the time-varying delay appears in both the state and the state derivative. The concepts of finite-time boundedness and finite-time stability are respectively extended to interconnected impulsive switched systems with neutral delay for the first time. By applying the average dwell time method, sufficient conditions are first derived to cope with the problem of finite-time boundedness and finite-time stability for interconnected impulsive switched systems with neutral delay. In addition, the purpose of finite-time resilient decentralized control is to construct a resilient decentralized state-feedback controller such that the closed-loop system is finite-time bounded and finite-time stable. All the conditions are formulated in terms of linear matrix inequalities to ensure finite-time boundedness and finite-time stability of the given system. Finally, an example is presented to illustrate the effectiveness of the proposed approach. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Probing Compulsive and Impulsive Behaviors, from Animal Models to Endophenotypes: A Narrative Review

PubMed Central

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

2010-01-01

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

Paralimbic and lateral prefrontal encoding of reward value during intertemporal choice in attempted suicide.

PubMed

Vanyukov, P M; Szanto, K; Hallquist, M N; Siegle, G J; Reynolds, C F; Forman, S D; Aizenstein, H J; Dombrovski, A Y

2016-01-01

Alongside impulsive suicide attempts, clinicians encounter highly premeditated suicidal acts, particularly in older adults. We have previously found that in contrast to the more impulsive suicide attempters' inability to delay gratification, serious and highly planned suicide attempts were associated with greater willingness to wait for larger rewards. This study examined neural underpinnings of intertemporal preference in suicide attempters. We expected that impulsivity and suicide attempts, particularly poorly planned ones, would predict altered paralimbic subjective value representations. We also examined lateral prefrontal and paralimbic correlates of premeditation in suicidal behavior. A total of 48 participants aged 46-90 years underwent extensive clinical and cognitive characterization and completed the delay discounting task in the scanner: 26 individuals with major depression (13 with and 13 without history of suicide attempts) and 22 healthy controls. More impulsive individuals displayed greater activation in the precuneus/posterior cingulate cortex (PCC) to value difference favoring the delayed option. Suicide attempts, particularly better-planned ones, were associated with deactivation of the lateral prefrontal cortex (lPFC) in response to value difference favoring the immediate option. Findings were robust to medication exposure, depression severity and possible brain damage from suicide attempts, among other confounders. Finally, in suicide attempters longer reward delays were associated with diminished parahippocampal responses. Impulsivity was associated with an altered paralimbic (precuneus/PCC) encoding of value difference during intertemporal choice. By contrast, better-planned suicidal acts were associated with altered lPFC representations of value difference. The study provides preliminary evidence of impaired decision processes in both impulsive and premeditated suicidal behavior.

Impulsivity in binge eating disorder: food cues elicit increased reward responses and disinhibition.

PubMed

Schag, Kathrin; Teufel, Martin; Junne, Florian; Preissl, Hubert; Hautzinger, Martin; Zipfel, Stephan; Giel, Katrin Elisabeth

2013-01-01

Binge eating disorder (BED) represents a distinct eating disorder diagnosis. Current approaches assume increased impulsivity to be one factor leading to binge eating and weight gain. We used eye tracking to investigate both components of impulsivity, namely reward sensitivity and rash-spontaneous behaviour towards food in BED for the first time. Overweight and obese people with BED (BED+; n = 25), without BED (BED-; n = 26) and healthy normal-weight controls (NWC; n = 25) performed a free exploration paradigm measuring reward sensitivity (experiment 1) and a modified antisaccade paradigm measuring disinhibited, rash-spontaneous behaviour (experiment 2) using food and nonfood stimuli. Additionally, trait impulsivity was assessed. In experiment 1, all participants located their initial fixations more often on food stimuli and BED+ participants gazed longer on food stimuli in comparison with BED- and NWC participants. In experiment 2, BED+ participants had more difficulties inhibiting saccades towards food and nonfood stimuli compared with both other groups in first saccades, and especially towards food stimuli in second saccades and concerning sequences of first and second saccades. BED- participants did not differ significantly from NWC participants in both experiments. Additionally, eye tracking performance was associated with self-reported reward responsiveness and self-control. According to these results, food-related reward sensitivity and rash-spontaneous behaviour, as the two components of impulsivity, are increased in BED in comparison with weight-matched and normal-weight controls. This indicates that BED represents a neurobehavioural phenotype of obesity that is characterised by increased impulsivity. Interventions for BED should target these special needs of affected patients.

The influence of cadence and power output on force application and in-shoe pressure distribution during cycling by competitive and recreational cyclists.

PubMed

Sanderson, D J; Hennig, E M; Black, A H

2000-03-01

The aim of this study was to determine the response of cyclists to manipulations of cadence and power output in terms of force application and plantar pressure distribution. Two groups of cyclists, 17 recreational and 12 competitive, rode at three nominal cadences (60, 80, 100 rev x min(-1)) and four power outputs (100, 200, 300, 400 W) while simultaneous force and in-shoe pressure data were collected. Two piezoelectric triaxial force transducers mounted in the right pedal measured components of the pedal force and orientation, and a discrete transducer system with 12 transducers recorded the in-shoe pressures. Force application was characterized by calculating peak resultant and peak effective pedal forces and positive and negative impulses. In-shoe pressures were analysed as peak pressures and as the percent relative load. The force data showed no significant group effect but there was a cadence and power main effect. The impulse data showed a significant three-way interaction. Increased cadence resulted in a decreased positive impulse, while increased power output resulted in an increased impulse. The competitive group produced less positive impulse but the difference became less at higher cadences. Few between-group differences were found in pressure, notable only in the pressure under the first metatarsal region. This showed a consistent pattern of in-shoe pressure distribution, where the primary loading structures were the first metatarsal and hallux. There was no indication that pressure at specific sites influenced the pedal force application. The absence of group differences indicated that pressure distribution was not the result of training, but reflected the intrinsic relationship between the foot, the shoe and the pedal.

Personality Factors Predicting Smartphone Addiction Predisposition: Behavioral Inhibition and Activation Systems, Impulsivity, and Self-Control

PubMed Central

Cho, Hyun; Jung, Dong-Jin; Kwak, Minjung; Rho, Mi Jung; Yu, Hwanjo; Kim, Dai-Jin; Choi, In Young

2016-01-01

The purpose of this study was to identify personality factor-associated predictors of smartphone addiction predisposition (SAP). Participants were 2,573 men and 2,281 women (n = 4,854) aged 20–49 years (Mean ± SD: 33.47 ± 7.52); participants completed the following questionnaires: the Korean Smartphone Addiction Proneness Scale (K-SAPS) for adults, the Behavioral Inhibition System/Behavioral Activation System questionnaire (BIS/BAS), the Dickman Dysfunctional Impulsivity Instrument (DDII), and the Brief Self-Control Scale (BSCS). In addition, participants reported their demographic information and smartphone usage pattern (weekday or weekend average usage hours and main use). We analyzed the data in three steps: (1) identifying predictors with logistic regression, (2) deriving causal relationships between SAP and its predictors using a Bayesian belief network (BN), and (3) computing optimal cut-off points for the identified predictors using the Youden index. Identified predictors of SAP were as follows: gender (female), weekend average usage hours, and scores on BAS-Drive, BAS-Reward Responsiveness, DDII, and BSCS. Female gender and scores on BAS-Drive and BSCS directly increased SAP. BAS-Reward Responsiveness and DDII indirectly increased SAP. We found that SAP was defined with maximal sensitivity as follows: weekend average usage hours > 4.45, BAS-Drive > 10.0, BAS-Reward Responsiveness > 13.8, DDII > 4.5, and BSCS > 37.4. This study raises the possibility that personality factors contribute to SAP. And, we calculated cut-off points for key predictors. These findings may assist clinicians screening for SAP using cut-off points, and further the understanding of SA risk factors. PMID:27533112

Personality Factors Predicting Smartphone Addiction Predisposition: Behavioral Inhibition and Activation Systems, Impulsivity, and Self-Control.

PubMed

Kim, Yejin; Jeong, Jo-Eun; Cho, Hyun; Jung, Dong-Jin; Kwak, Minjung; Rho, Mi Jung; Yu, Hwanjo; Kim, Dai-Jin; Choi, In Young

2016-01-01

The purpose of this study was to identify personality factor-associated predictors of smartphone addiction predisposition (SAP). Participants were 2,573 men and 2,281 women (n = 4,854) aged 20-49 years (Mean ± SD: 33.47 ± 7.52); participants completed the following questionnaires: the Korean Smartphone Addiction Proneness Scale (K-SAPS) for adults, the Behavioral Inhibition System/Behavioral Activation System questionnaire (BIS/BAS), the Dickman Dysfunctional Impulsivity Instrument (DDII), and the Brief Self-Control Scale (BSCS). In addition, participants reported their demographic information and smartphone usage pattern (weekday or weekend average usage hours and main use). We analyzed the data in three steps: (1) identifying predictors with logistic regression, (2) deriving causal relationships between SAP and its predictors using a Bayesian belief network (BN), and (3) computing optimal cut-off points for the identified predictors using the Youden index. Identified predictors of SAP were as follows: gender (female), weekend average usage hours, and scores on BAS-Drive, BAS-Reward Responsiveness, DDII, and BSCS. Female gender and scores on BAS-Drive and BSCS directly increased SAP. BAS-Reward Responsiveness and DDII indirectly increased SAP. We found that SAP was defined with maximal sensitivity as follows: weekend average usage hours > 4.45, BAS-Drive > 10.0, BAS-Reward Responsiveness > 13.8, DDII > 4.5, and BSCS > 37.4. This study raises the possibility that personality factors contribute to SAP. And, we calculated cut-off points for key predictors. These findings may assist clinicians screening for SAP using cut-off points, and further the understanding of SA risk factors.

International Comparison Test in Asia-Pacific Region for Impulse Voltage Measurements

NASA Astrophysics Data System (ADS)

Wakimoto, Takayuki; Ishii, Masaru; Goshima, Hisashi; Hino, Etsuhiro; Shimizu, Hiroyuki; Li, Yi; Ik-Soo, Kim

The national standard class divider for the lightning impulse voltage measurements in Japan was developed in 1998. After three years, the standard impulse voltage calibrator was manufactured, too. These standard equipment are used as an industrial standard, and the performance had been evaluated annually supported by Ministry of Economy, Trade and Industry (METI). The standard impulse measuring system including the standard divider participated in the worldwide comparison test and its good performance was confirmed in 1999. Another international comparison test was carried out among three countries in the Asia-Pacific region in 2004 again and the standard measuring system participated in the test. In this paper, the details and the results of the international comparison tests in 2004 are described.

An expandable crosstalk reduction method for inline fiber Fabry-Pérot sensor array based on fiber Bragg gratings

NASA Astrophysics Data System (ADS)

Jiang, Peng; Ma, Lina; Hu, Zhengliang; Hu, Yongming

2016-07-01

The inline time division multiplexing (TDM) fiber Fabry-Pérot (FFP) sensor array based on fiber Bragg gratings (FBGs) is attractive for many applications. But the intrinsic multi-reflection (MR) induced crosstalk limits applications especially those needing high resolution. In this paper we proposed an expandable method for MR-induced crosstalk reduction. The method is based on complexing-exponent synthesis using the phase-generated carrier (PGC) scheme and the special common character of the impulse responses. The method could promote demodulation stability simultaneously with the reduction of MR-induced crosstalk. A polarization-maintaining 3-TDM experimental system with an FBG reflectivity of about 5 % was set up to validate the method. The experimental results showed that crosstalk reduction of 13 dB and 15 dB was achieved for sensor 2 and sensor 3 respectively when a signal was applied to the first sensor and crosstalk reduction of 8 dB was achieved for sensor 3 when a signal was applied to sensor 2. The demodulation stability of the applied signal was promoted as well. The standard deviations of the amplitude distributions of the demodulated signals were reduced from 0.0046 to 0.0021 for sensor 2 and from 0.0114 to 0.0044 for sensor 3. Because of the convenience of the linear operation of the complexing-exponent and according to the common character of the impulse response we found, the method can be effectively extended to the array with more TDM channels if the impulse response of the inline FFP sensor array with more TDM channels is derived. It offers potential to develop a low-crosstalk inline FFP sensor array using the PGC interrogation technique with relatively high reflectivity FBGs which can guarantee enough light power received by the photo-detector.

Phase Diversity and Polarization Augmented Techniques for Active Imaging

DTIC Science & Technology

2007-03-01

build up a system model for use in algorithm development. 32 IV. Conventional Imaging and Atmospheric Turbulence With an understanding of scalar...28, 59, 115 Cholesky Factorization, 14, 42 C2n, see Turbulence Coherent Image Model, 36 Complete Data, see EM Algorithm Complex Coherence...Data, see EM Algorithm Homotopic, 62 Impulse Response, 34, 44 Incoherent Image Model, 36 Incomplete Data, see EM Algorithm Lo- Turbulence Outer Scale

A general method to correct PET data for tissue metabolites using a dual-scan approach.

PubMed

Gunn, R N; Yap, J T; Wells, P; Osman, S; Price, P; Jones, T; Cunningham, V J

2000-04-01

This article presents and analyses a general method of correcting for the presence of radiolabeled metabolites from a parent radiotracer in tissue during PET scanning. The method is based on a dual-scan approach, i.e., parent scan together with an independent supplementary scan in which the radiolabeled metabolite of interest itself is administered. The method corrects for the presence of systemically derived radiolabeled metabolite delivered to the tissues of interest through the blood. Data from the supplementary scan are analyzed to obtain the tissue impulse response function for the metabolite. The time course of the radiolabeled metabolite in plasma in the parent scan is convolved with its tissue impulse response function to derive a correction term. This is not a simple subtraction technique but 1 that takes account of the different time-activity curves of the radiolabeled metabolite in the 2 scans. The method, its implications, and its limitations are discussed with respect to [11C]thymidine and its principal metabolite 11CO2. The general method, based on a dual-scan approach, can be used to correct for radiolabeled metabolites in tissues of interest during PET scanning. The correction accounts for radiolabeled metabolites that are derived systemically and delivered to the tissues of interest through the blood.

Respiratory sinus arrhythmia: time domain characterization using autoregressive moving average analysis

NASA Technical Reports Server (NTRS)

Triedman, J. K.; Perrott, M. H.; Cohen, R. J.; Saul, J. P.

1995-01-01

Fourier-based techniques are mathematically noncausal and are therefore limited in their application to feedback-containing systems, such as the cardiovascular system. In this study, a mathematically causal time domain technique, autoregressive moving average (ARMA) analysis, was used to parameterize the relations of respiration and arterial blood pressure to heart rate in eight humans before and during total cardiac autonomic blockade. Impulse-response curves thus generated showed the relation of respiration to heart rate to be characterized by an immediate increase in heart rate of 9.1 +/- 1.8 beats.min-1.l-1, followed by a transient mild decrease in heart rate to -1.2 +/- 0.5 beats.min-1.l-1 below baseline. The relation of blood pressure to heart rate was characterized by a slower decrease in heart rate of -0.5 +/- 0.1 beats.min-1.mmHg-1, followed by a gradual return to baseline. Both of these relations nearly disappeared after autonomic blockade, indicating autonomic mediation. Maximum values obtained from the respiration to heart rate impulse responses were also well correlated with frequency domain measures of high-frequency "vagal" heart rate control (r = 0.88). ARMA analysis may be useful as a time domain representation of autonomic heart rate control for cardiovascular modeling.

Response of end tidal CO2 pressure to impulse exercise.

PubMed

Yano, T; Afroundeh, R; Yamanak, R; Arimitsu, T; Lian, C-S; Shirkawa, K; Yunoki, T

2014-03-01

The purpose of the present study was to examine how end tidal CO(2) pressure (PETCO(2)) is controlled in impulse exercise. After pre-exercise at 25 watts for 5 min, impulse exercise for 10 sec with 200 watts followed by post exercise at 25 watts was performed. Ventilation (VE) significantly increased until the end of impulse exercise and significantly re-increased after a sudden decrease. Heart rate (HR) significantly increased until the end of impulse exercise and then decreased to the pre-exercise level. PETCO(2) remained constant during impulse exercise. PETCO(2) significantly increased momentarily after impulse exercise and then significantly decreased to the pre-exercise level. PETCO(2) showed oscillation. The average peak frequency of power spectral density in PETCO(2) appeared at 0.0078 Hz. Cross correlations were obtained after impulse exercise. The peak cross correlations between VE and PETCO(2), HR and PETCO(2), and VE and HR were 0.834 with a time delay of -7 sec, 0.813 with a time delay of 7 sec and 0.701 with a time delay of -15 sec, respectively. We demonstrated that PETCO(2) homeodynamics was interactively maintained by PETCO(2) itself, CO(2) transportation (product of cardiac output and mixed venous CO(2) content) into the lungs by heart pumping and CO(2) elimination by ventilation, and it oscillates as a result of their interactions.

Advantage of impulse oscillometry over spirometry to diagnose chronic obstructive pulmonary disease and monitor pulmonary responses to bronchodilators: An observational study.

PubMed

Saadeh, Constantine; Saadeh, Charles; Cross, Blake; Gaylor, Michael; Griffith, Melissa

2015-01-01

This retrospective study was a comparative analysis of sensitivity of impulse oscillometry and spirometry techniques for use in a mixed chronic obstructive pulmonary disease group for assessing disease severity and inhalation therapy. A total of 30 patients with mild-to-moderate chronic obstructive pulmonary disease were monitored by impulse oscillometry, followed by spirometry. Lung function was measured at baseline after bronchodilation and at follow-up (3-18 months). The impulse oscillometry parameters were resistance in the small and large airways at 5 Hz (R5), resistance in the large airways at 15 Hz (R15), and lung reactance (area under the curve X; AX). After the bronchodilator therapy, forced expiratory volume in 1 second (FEV1) readings evaluated by spirometry were unaffected at baseline and at follow-up, while impulse oscillometry detected an immediate improvement in lung function, in terms of AX (p = 0.043). All impulse oscillometry parameters significantly improved at follow-up, with a decrease in AX by 37% (p = 0.0008), R5 by 20% (p = 0.0011), and R15 by 12% (p = 0.0097). Impulse oscillometry parameters demonstrated greater sensitivity compared with spirometry for monitoring reversibility of airway obstruction and the effect of maintenance therapy. Impulse oscillometry may facilitate early treatment dose optimization and personalized medicine for chronic obstructive pulmonary disease patients.

Modelling and stability analysis of switching impulsive power systems with multiple equilibria

NASA Astrophysics Data System (ADS)

Zhu, Liying; Qiu, Jianbin; Chadli, Mohammed

2017-12-01

This paper tries to model power systems accompanied with a series of faults in the form of switched impulsive Hamiltonian systems (SIHSs) with multiple equilibria (ME) and unstable subsystems (US), and then analyze long-term stability issues of the power systems from the viewpoint of mathematics. According to the complex phenomena of switching actions of stages and generators, impulses of state, and existence of multiple equilibria, this paper first introduces an SIHS with ME and US to formulate a switching impulsive power system composed of an active generator, a standby generator, and an infinite load. Then, based on special system structures, a unique compact region containing all ME is determined, and novel stability concepts of region stability (RS), asymptotic region stability (ARS), and exponential region stability (ERS) are defined for such SIHS with respect to the region. Third, based on the introduced stability concepts, this paper proposes a necessary and sufficient condition of RS and ARS and a sufficient condition of ERS for the power system with respect to the region via the maximum energy function method. Finally, numerical simulations are carried out for a power system to show the effectiveness and practicality of the obained novel results.

The scattering of electromagnetic pulses by a slit in a conducting screen

NASA Technical Reports Server (NTRS)

Ackerknecht, W. E., III; Chen, C.-L.

1975-01-01

A direct method for calculating the impulse response of a slit in a conducting screen is presented which is derived specifically for the analysis of transient scattering by two-dimensional objects illuminated by a plane incident wave. The impulse response is obtained by assuming that the total response is composed of two sequences of diffracted waves. The solution is determined for the first two waves in one sequence by using Green's functions and the equivalence principle, for additional waves in the sequence by iteration, and for the other sequence by a transformation of coordinates. The cases of E-polarization and H-polarization are considered.

Impulse processing: A dynamical systems model of incremental eye movements in the visual world paradigm

PubMed Central

Kukona, Anuenue; Tabor, Whitney

2011-01-01

The visual world paradigm presents listeners with a challenging problem: they must integrate two disparate signals, the spoken language and the visual context, in support of action (e.g., complex movements of the eyes across a scene). We present Impulse Processing, a dynamical systems approach to incremental eye movements in the visual world that suggests a framework for integrating language, vision, and action generally. Our approach assumes that impulses driven by the language and the visual context impinge minutely on a dynamical landscape of attractors corresponding to the potential eye-movement behaviors of the system. We test three unique predictions of our approach in an empirical study in the visual world paradigm, and describe an implementation in an artificial neural network. We discuss the Impulse Processing framework in relation to other models of the visual world paradigm. PMID:21609355

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.

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.

Sensitivity of caloric test and video head impulse as screening test for chronic vestibular complaints.

PubMed

Mezzalira, Raquel; Bittar, Roseli Saraiva Moreira; do Carmo Bilécki-Stipsky, Marcia Maria; Brugnera, Cibele; Grasel, Signe Schuster

2017-08-01

This study compared the results of the caloric test with those of the video head impulse test obtained during the same session and evaluated whether the former can be used to screen for non-acute vestibular dysfunction. A total of 157 participants complaining of dizziness with vestibular characteristics of varying durations and clinical courses completed the caloric test and video head impulse test. Significantly more caloric test results than video head impulse test results were abnormal. The results of the caloric test and video head impulse test are distinct but complement each other. Within our sample, the caloric test was more sensitive for vestibular dysfunction. Therefore, the video head impulse test is not a suitable screening tool of the vestibular system in patients with chronic complaints.

Order reduction of z-transfer functions via multipoint Jordan continued-fraction expansion

NASA Technical Reports Server (NTRS)

Lee, Ying-Chin; Hwang, Chyi; Shieh, Leang S.

1992-01-01

The order reduction problem of z-transfer functions is solved by using the multipoint Jordan continued-fraction expansion (MJCFE) technique. An efficient algorithm that does not require the use of complex algebra is presented for obtaining an MJCFE from a stable z-transfer function with expansion points selected from the unit circle and/or the positive real axis of the z-plane. The reduced-order models are exactly the multipoint Pade approximants of the original system and, therefore, they match the (weighted) time-moments of the impulse response and preserve the frequency responses of the system at some characteristic frequencies, such as gain crossover frequency, phase crossover frequency, bandwidth, etc.

Tracking rainfall impulses through progressively larger drainage basins in steep forested terrain

Treesearch

R. R. Ziemer; R. M. Rice

1990-01-01

Abstract - The precision of timing devices in modern electronic data loggers makes it possible to study the routing of water through small drainage basins having rapid responses to hydrologic impulses. Storm hyetographs were measured using digital tipping bucket rain gauges and their routing was observed at headwater piezometers located mid-slope, above a swale, and...

X-ray transport and radiation response assessment (XTRRA) experiments at the National Ignition Facility.

PubMed

Fournier, K B; Brown, C G; Yeoman, M F; Fisher, J H; Seiler, S W; Hinshelwood, D; Compton, S; Holdener, F R; Kemp, G E; Newlander, C D; Gilliam, R P; Froula, N; Lilly, M; Davis, J F; Lerch, Maj A; Blue, B E

2016-11-01

Our team has developed an experimental platform to evaluate the x-ray-generated stress and impulse in materials. Experimental activities include x-ray source development, design of the sample mounting hardware and sensors interfaced to the National Ignition Facility's diagnostics insertion system, and system integration into the facility. This paper focuses on the X-ray Transport and Radiation Response Assessment (XTRRA) test cassettes built for these experiments. The test cassette is designed to position six samples at three predetermined distances from the source, each known to within ±1% accuracy. Built-in calorimeters give in situ measurements of the x-ray environment along the sample lines of sight. The measured accuracy of sample responses as well as planned modifications to the XTRRA cassette is discussed.

Alterations of Brain Functional Architecture Associated with Psychopathic Traits in Male Adolescents with Conduct Disorder.

PubMed

Pu, Weidan; Luo, Qiang; Jiang, Yali; Gao, Yidian; Ming, Qingsen; Yao, Shuqiao

2017-09-12

Psychopathic traits of conduct disorder (CD) have a core callous-unemotional (CU) component and an impulsive-antisocial component. Previous task-driven fMRI studies have suggested that psychopathic traits are associated with dysfunction of several brain areas involved in different cognitive functions (e.g., empathy, reward, and response inhibition etc.), but the relationship between psychopathic traits and intrinsic brain functional architecture has not yet been explored in CD. Using a holistic brain-wide functional connectivity analysis, this study delineated the alterations in brain functional networks in patients with conduct disorder. Compared with matched healthy controls, we found decreased anti-synchronization between the fronto-parietal network (FPN) and default mode network (DMN), and increased intra-network synchronization within the frontothalamic-basal ganglia, right frontoparietal, and temporal/limbic/visual networks in CD patients. Correlation analysis showed that the weakened FPN-DMN interaction was associated with CU traits, while the heightened intra-network functional connectivity was related to impulsivity traits in CD patients. Our findings suggest that decoupling of cognitive control (FPN) with social understanding of others (DMN) is associated with the CU traits, and hyper-functions of the reward and motor inhibition systems elevate impulsiveness in CD.

Controller reduction by preserving impulse response energy

NASA Technical Reports Server (NTRS)

Craig, Roy R., Jr.; Su, Tzu-Jeng

1989-01-01

A model order reduction algorithm based on a Krylov recurrence formulation is developed to reduce order of controllers. The reduced-order controller is obtained by projecting the full-order LQG controller onto a Krylov subspace in which either the controllability or the observability grammian is equal to the identity matrix. The reduced-order controller preserves the impulse response energy of the full-order controller and has a parameter-matching property. Two numerical examples drawn from other controller reduction literature are used to illustrate the efficacy of the proposed reduction algorithm.

Bubble mass center and fluid feedback force fluctuations activated by constant lateral impulse with variable thrust

NASA Technical Reports Server (NTRS)

Hung, R. J.; Long, Y. T.

1995-01-01

Sloshing dynamics within a partially filled rotating dewar of superfluid helium 2 are investigated in response to constant lateral impulse with variable thrust. The study, including how the rotating bubble of superfluid helium 2 reacts to the constant impulse with variable time period of thrust action in microgravity, how amplitudes of bubble mass center fluctuates with growth and decay of disturbances, and how fluid feedback forces fluctuates in activating on the rotating dewar through the dynamics of sloshing waves are investigated. The numerical computation of sloshing dynamics is based on the non-inertial frame spacecraft bound coordinate with lateral impulses actuating on the rotating dewar in both inertial and non-inertial frames of thrust. Results of the simulations are illustrated.

Dissociable effects of cocaine and yohimbine on impulsive action and relapse to cocaine seeking.

PubMed

Broos, Nienke; van Mourik, Yvar; Schetters, Dustin; De Vries, Taco J; Pattij, Tommy

2017-11-01

A strong association has been demonstrated between various forms of impulsivity and addiction-like behavior in both humans and rats. In this study, we investigated how impulsive action, as measured in the 5-choice serial reaction time task (5-CSRTT), is affected during various stages of cocaine taking and seeking and by relapse-provoking stimuli in animals that were trained both in an intravenous cocaine self-administration paradigm and in the 5-CSRTT. Rats were concurrently trained in the 5-CSRTT and cocaine self-administration protocol, and subsequently, the effects of cocaine (7.5 mg/kg) and the pharmacological stressor yohimbine (1.25 mg/kg) were tested in both paradigms. Cocaine self-administration (5 h/day) transiently altered impulsive action and increased errors of omission in the 5-CSRTT. Pharmacological challenges with cocaine and yohimbine induced increments in impulsive action and reinstated cocaine-seeking responses within the same animals. Further analyses revealed that the effects of cocaine and yohimbine on impulsive action did not correlate with their effects on reinstatement of cocaine seeking. These data suggest that although impulsive action and relapse can be pharmacologically modulated in the same direction within individuals, these effects appear not to be directly coupled.

Amygdala reactivity to fearful faces correlates positively with impulsive aggression.

PubMed

da Cunha-Bang, Sofi; Fisher, Patrick M; Hjordt, Liv V; Holst, Klaus; Knudsen, Gitte M

2018-01-07

Facial expressions robustly activate the amygdala, a brain structure playing a critical role in aggression. Whereas previous studies suggest that amygdala reactivity is related to various measures of impulsive aggression, we here estimate a composite measure of impulsive aggression and evaluate whether it is associated with amygdala reactivity to angry and fearful faces. We estimated amygdala reactivity with functional magnetic resonance imaging in 47 men with varying degree of aggressive traits (19 incarcerated violent offenders and 28 healthy controls). We modeled a composite "impulsive aggression" trait construct (LV agg ) using a linear structural equation model, with a single latent variable capturing the shared correlation between five self-report measures of trait aggression, anger and impulsivity. We tested for associations between amygdala reactivity and the LV agg , adjusting for age and group. The LV agg was significantly positively associated with amygdala reactivity to fearful (p = 0.001), but not angry faces (p = 0.9). We found no group difference in amygdala reactivity to fearful or angry faces. The findings suggest that that amygdala reactivity to fearful faces is represented by a composite index of impulsive aggression and provide evidence that impulsive aggression is associated with amygdala reactivity in response to submissive cues, i.e., fearful faces.

Examination of the heterogeneity in PTSD and impulsivity facets: A latent profile analysis.

PubMed

Contractor, Ateka A; Caldas, Stephanie; Weiss, Nicole H; Armour, Cherie

2018-04-15

The experience of traumatizing events and resulting posttraumatic stress disorder (PTSD) symptomology relates to a range of impulsive behaviors. While both PTSD and impulsivity are heterogeneous and multidimensional constructs, no research has used person-centered approaches to examine subgroups of individuals based on these response endorsements. Hence, our study examined PTSD-impulsivity typologies and their construct validity in two samples: university students ( n = 412) and community participants recruited through Amazon's MTurk ( n = 346). Measures included the Stressful Life Events Screening Questionnaire (PTEs), PTSD Checklist for DSM-5 (PTSD severity), UPPS Impulsive Behavior Scale (negative urgency, lack of premeditation, lack of perseverance, sensation seeking). Dimensions of Anger Reaction Scale (anger), and the Patient Health Questionnaire-9 (depression). For both samples, results of latent profile analyses indicated a best-fitting 3-class solution: High, Moderate, and Low PTSD-Negative Urgency. Negative urgency was the most distinguishing impulsivity facet. Anger and depression severity significantly predicted membership in the more severe symptomatology classes. Thus, individuals can be meaningfully categorized into three subgroups based on PTSD and impulsivity item endorsements. We provide some preliminary evidence for a negative urgency subtype of PTSD characterized by greater depression and anger regulation difficulties; and underscore addressing emotional regulation skills for these subgroup members.

Aggression, Suicidality, and Intermittent Explosive Disorder: Serotonergic Correlates in Personality Disorder and Healthy Control Subjects

PubMed Central

Coccaro, Emil F; Lee, Royce; Kavoussi, Richard J

2010-01-01

Central serotonergic (5-HT) activity has long been implicated in the regulation of impulsive aggressive behavior. This study was performed to use a highly selective agent for 5-HT (d-Fenfluramine, d-FEN) in a large group of human subjects to further explore this relationship dimensionally and categorically. One hundred and fifty healthy subjects (100 with personality disorder, PD and 50 healthy volunteer controls, HV) underwent d-FEN challenge studies. Residual peak delta prolactin (ΔPRL[d-FEN]-R; ie, after the removal of potentially confounding variables) was used as the primary 5-HT response variable. Composite measures of aggression and impulsivity were used as dimensional measures, and history of suicidal/self-injurious behavior as well as the presence of intermittent explosive disorder (IED) were used as categorical variables. ΔPRL[d-FEN]-R responses correlated inversely with composite aggression, but not composite impulsivity, in all subjects and in males and females examined separately. The correlation with composite aggression was strongest in male PD subjects. ΔPRL[d-FEN]-R values were reduced in PD subjects with a history of suicidal behavior but not, self-injurious behavior. ΔPRL[d-FEN]-R values were also reduced in patients meeting Research Criteria for IED. Physiologic responses to 5-HT stimulation are reduced as a function of aggression (but not generalized impulsivity) in human subjects. The same is true for personality disordered subjects with a history of suicidal, but not self-injurious, behavior and for subjects with a diagnosis of IED by research criteria. These data have particular relevance to the notion of impulsive aggression and the biological validity of IED. PMID:19776731

Sex differences in impulsivity and brain morphometry in methamphetamine users

PubMed Central

Kogachi, Shannon; Chang, Linda; Alicata, Daniel; Cunningham, Eric; Ernst, Thomas

2016-01-01

Methamphetamine (METH) is an addictive stimulant, and METH users have abnormal brain structures and function. The aims of this study were to investigate the relationships between impulsivity, brain structures, and possible sex-specific differences between METH users and non-drug using Controls. Structural MRI and the Barratt Impulsiveness Scale (BIS) questionnaire were completed in 124 subjects: 62 METH (ages 41.2 ± 1.4 years, 34 males) and 62 Controls (ages 43.3 ± 2.3 years, 36 males). Independent and interactive effects of METH use status and sex were evaluated. Relationships between METH usage characteristics, brain morphometry, and impulsivity scores were examined. METH users had higher impulsivity scores, on both the Cognitive and Behavioral Factors from the BIS (p < 0.0001–0.0001). Compared with same-sex Controls, male METH users had larger, while female METH users had smaller, right superior frontal cortex (interaction-p = 0.0005). The male METH users with larger frontal volumes and female METH users with smaller or thinner frontal cortices had greater Cognitive impulsivity (interaction-p ≤ 0.05). Only female METH users showed relatively larger nucleus accumbens (interaction-p = 0.03). Greater impulsivity and thinner frontal cortices in METH users are validated. Larger superior frontal cortex in male METH users with greater cognitive impulsivity suggest decreased dendritic pruning during adolescence might have contributed to their impulsive and drug use behaviors. In the female METH users, smaller frontal cortices and the associated greater impulsivity suggest greater neurotoxicity to these brain regions, while their relatively larger nucleus accumbens suggest an estrogen-mediated neuroprotective glial response. Men and women may be affected differently by METH use. PMID:27095357

Sex differences in impulsivity and brain morphometry in methamphetamine users.

PubMed

Kogachi, Shannon; Chang, Linda; Alicata, Daniel; Cunningham, Eric; Ernst, Thomas

2017-01-01

Methamphetamine (METH) is an addictive stimulant, and METH users have abnormal brain structures and function. The aims of this study were to investigate the relationships between impulsivity, brain structures, and possible sex-specific differences between METH users and non-drug using Controls. Structural MRI and the Barratt Impulsiveness Scale (BIS) questionnaire were completed in 124 subjects: 62 METH (ages 41.2 ± 1.4 years, 34 males) and 62 Controls (ages 43.3 ± 2.3 years, 36 males). Independent and interactive effects of METH use status and sex were evaluated. Relationships between METH usage characteristics, brain morphometry, and impulsivity scores were examined. METH users had higher impulsivity scores, on both the Cognitive and Behavioral Factors from the BIS (p < 0.0001-0.0001). Compared with same-sex Controls, male METH users had larger, while female METH users had smaller, right superior frontal cortex (interaction-p = 0.0005). The male METH users with larger frontal volumes and female METH users with smaller or thinner frontal cortices had greater Cognitive impulsivity (interaction-p ≤ 0.05). Only female METH users showed relatively larger nucleus accumbens (interaction-p = 0.03). Greater impulsivity and thinner frontal cortices in METH users are validated. Larger superior frontal cortex in male METH users with greater cognitive impulsivity suggest decreased dendritic pruning during adolescence might have contributed to their impulsive and drug use behaviors. In the female METH users, smaller frontal cortices and the associated greater impulsivity suggest greater neurotoxicity to these brain regions, while their relatively larger nucleus accumbens suggest an estrogen-mediated neuroprotective glial response. Men and women may be affected differently by METH use.

Lesions to the subthalamic nucleus decrease impulsive choice but impair autoshaping in rats: the importance of the basal ganglia in Pavlovian conditioning and impulse control.

PubMed

Winstanley, Catharine A; Baunez, Christelle; Theobald, David E H; Robbins, Trevor W

2005-06-01

Although the subthalamic nucleus (STN) is involved in regulating motor function, and inactivation of this structure relieves the motor symptoms in Parkinsonian patients, recent data indicate that corticosubthalamic connections are involved in both the regulation of attention and the ability to withhold from responding. Considerable evidence suggests that the neural circuitry underlying such behavioural disinhibition or impulsive action can be at least partially dissociated from that implicated in impulsive decision-making and it has been suggested that the tendency to choose impulsively is related to the ability to form and use Pavlovian associations. To explore these hypotheses further, STN-lesioned rats were tested on the delay-discounting model of impulsive choice, where impulsivity is defined as the selection of a small immediate over a larger delayed reward, as well as in a rodent autoshaping paradigm. In contrast to previous reports of increased impulsive action, STN lesions decreased impulsive choice but dramatically impaired the acquisition of the autoshaping response. When the STN was lesioned after the establishment of autoshaping behaviour, lesioned subjects were more sensitive to the omission of reward, indicative of a reduction in the use of Pavlovian associations to control autoshaping performance. These results emphasize the importance of the STN in permitting conditioned stimulus-unconditioned stimulus associations to regulate goal-seeking, a function which may relate to the alterations in impulsive choice observed in the delay-discounting task. These data bear a striking similarity to those observed after lesions of the orbitofrontal cortex and are suggestive of an important role for corticosubthalamic connections in complex cognitive behaviour.

Unleashing elastic energy: dynamics of energy release in rubber bands and impulsive biological systems

NASA Astrophysics Data System (ADS)

Ilton, Mark; Cox, Suzanne; Egelmeers, Thijs; Patek, S. N.; Crosby, Alfred J.

Impulsive biological systems - which include mantis shrimp, trap-jaw ants, and venus fly traps - can reach high speeds by using elastic elements to store and rapidly release energy. The material behavior and shape changes critical to achieving rapid energy release in these systems are largely unknown due to limitations of materials testing instruments operating at high speed and large displacement. In this work, we perform fundamental, proof-of-concept measurements on the tensile retraction of elastomers. Using high speed imaging, the kinematics of retraction are measured for elastomers with varying mechanical properties and geometry. Based on the kinematics, the rate of energy dissipation in the material is determined as a function of strain and strain-rate, along with a scaling relation which describes the dependence of maximum velocity on material properties. Understanding this scaling relation along with the material failure limits of the elastomer allows the prediction of material properties required for optimal performance. We demonstrate this concept experimentally by optimizing for maximum velocity in our synthetic model system, and achieve retraction velocities that exceed those in biological impulsive systems. This model system provides a foundation for future work connecting continuum performance to molecular architecture in impulsive systems.

Characterization of advanced electric propulsion systems

NASA Technical Reports Server (NTRS)

Ray, P. K.

1982-01-01

Characteristics of several advanced electric propulsion systems are evaluated and compared. The propulsion systems studied are mass driver, rail gun, MPD thruster, hydrogen free radical thruster and mercury electron bombardment ion engine. These are characterized by specific impulse, overall efficiency, input power, average thrust, power to average thrust ratio and average thrust to dry weight ratio. Several important physical characteristics such as dry system mass, accelerator length, bore size and current pulse requirement are also evaluated in appropriate cases. Only the ion engine can operate at a specific impulse beyond 2000 sec. Rail gun, MPD thruster and free radical thruster are currently characterized by low efficiencies. Mass drivers have the best performance characteristics in terms of overall efficiency, power to average thrust ratio and average thrust to dry weight ratio. But, they can only operate at low specific impulses due to large power requirements and are extremely long due to limitations of driving current. Mercury ion engines have the next best performance characteristics while operating at higher specific impulses. It is concluded that, overall, ion engines have somewhat better characteristics as compared to the other electric propulsion systems.

The effects of reinforcement and response-cost on a delayed response task in children with attention deficit hyperactivity disorder: a research note.

PubMed

Solanto, M V

1990-07-01

Children with attention deficit hyperactivity disorder are more inattentive, active, and impulsive than normal children. Some researchers have postulated that these symptoms can all be explained as a result of reduced sensitivity to reinforcement. In order to evaluate this hypothesis, we tested 20 ADD-H children and 18 matched normal controls, 4 1/2-11 years of age, on a delayed response task, a measure of impulsiveness, under conditions of positive reinforcement, and punishment in the form of response-cost. The contingencies each improved performance compared to baseline but did not differ significantly from each other. Neither contingency affected the groups differentially, thus failing to provide support for the reinforcement hypothesis.

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

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

Left-right asymmetry in firing rate of extra-retinal photosensitive neurons in the crayfish.

PubMed

Pacheco-Ortiz, José A; Sánchez-Hernández, Juan C; Rodríguez-Sosa, Leonardo; Calderón-Rosete, Gabina; Villagran-Vargas, Edgar

2018-01-01

The purpose of this paper is to explore the firing rate of the caudal photoreceptors (CPRs) from the sixth abdominal ganglion of the crayfish Cherax quadricarinatus. We use simultaneous extracellular recordings on left and right CPR in the isolated ganglion (n = 10). The CPRs showed an asymmetry in the spontaneous activity and light-induced response. In darkness, we observed one subgroup (70%) in which the left CPR (CPR-L) and right CPR (CPR-R) had spontaneous firing rates with a median of 18 impulses/s and 6 impulses/s, respectively. In another subgroup (20%), the CPR-R had a median of 15 impulses/s and the CPR-L had 8 impulses/s. In both groups, the differences were significant. Furthermore, the CPRs showed an asymmetrical photoresponse induced by a pulse of white light (700 Lux, 4 s). In one subgroup (30%), the CPR-L showed light-induced activity with a median of 73%, (interquartile range, IQR = 51), while the CPR-R had a median of 41%, (IQR = 47). In another subgroup (70%), the CPR-R showed a median of 56%, (IQR = 51) and the CPR-L had a median of 42%, (IQR = 46). In both groups, the differences were significant. Moreover, we observed a differential effect of temperature on CPR activity. These results suggest a functional asymmetry in both activities from left and right CPRs. These CPR activity fluctuations may modulate the processing of information by the nervous system.

Inflammation and lithium: clues to mechanisms contributing to suicide-linked traits

PubMed Central

Beurel, E; Jope, R S

2014-01-01

Suicide is one of the leading causes of death in the United States, yet it remains difficult to understand the mechanistic provocations and to intervene therapeutically. Stress is recognized as a frequent precursor to suicide. Psychological stress is well established to cause activation of the inflammatory response, including causing neuroinflammation, an increase of inflammatory molecules in the central nervous system (CNS). Neuroinflammation is increasingly recognized as affecting many aspects of CNS functions and behaviors. In particular, much evidence demonstrates that inflammatory markers are elevated in traits that have been linked to suicidal behavior, including aggression, impulsivity and depression. Lithium is recognized as significantly reducing suicidal behavior, is anti-inflammatory and diminishes aggression, impulsivity and depression traits, each of which is associated with elevated inflammation. The anti-inflammatory effects of lithium result from its inhibition of glycogen synthase kinase-3 (GSK3). GSK3 has been demonstrated to strongly promote inflammation, aggressive behavior in rodents and depression-like behaviors in rodents, whereas regulation of impulsivity by GSK3 has not yet been investigated. Altogether, evidence is building supporting the hypothesis that stress activates GSK3, which in turn promotes inflammation, and that inflammation is linked to behaviors associated with suicide, including particularly aggression, impulsivity and depression. Further investigation of these links may provide a clearer understanding of the causes of suicidal behavior and provide leads for the development of effective preventative interventions, which may include inhibitors of GSK3. PMID:25514751

Inflammation and lithium: clues to mechanisms contributing to suicide-linked traits.

PubMed

Beurel, E; Jope, R S

2014-12-16

Suicide is one of the leading causes of death in the United States, yet it remains difficult to understand the mechanistic provocations and to intervene therapeutically. Stress is recognized as a frequent precursor to suicide. Psychological stress is well established to cause activation of the inflammatory response, including causing neuroinflammation, an increase of inflammatory molecules in the central nervous system (CNS). Neuroinflammation is increasingly recognized as affecting many aspects of CNS functions and behaviors. In particular, much evidence demonstrates that inflammatory markers are elevated in traits that have been linked to suicidal behavior, including aggression, impulsivity and depression. Lithium is recognized as significantly reducing suicidal behavior, is anti-inflammatory and diminishes aggression, impulsivity and depression traits, each of which is associated with elevated inflammation. The anti-inflammatory effects of lithium result from its inhibition of glycogen synthase kinase-3 (GSK3). GSK3 has been demonstrated to strongly promote inflammation, aggressive behavior in rodents and depression-like behaviors in rodents, whereas regulation of impulsivity by GSK3 has not yet been investigated. Altogether, evidence is building supporting the hypothesis that stress activates GSK3, which in turn promotes inflammation, and that inflammation is linked to behaviors associated with suicide, including particularly aggression, impulsivity and depression. Further investigation of these links may provide a clearer understanding of the causes of suicidal behavior and provide leads for the development of effective preventative interventions, which may include inhibitors of GSK3.

Callous-unemotional, impulsive-irresponsible, and grandiose-manipulative traits: Distinct associations with heart rate, skin conductance, and startle responses to violent and erotic scenes.

PubMed

Fanti, Kostas A; Kyranides, Melina N; Georgiou, Giorgos; Petridou, Maria; Colins, Olivier F; Tuvblad, Catherine; Andershed, Henrik

2017-05-01

The present study aimed to examine whether callous-unemotional, grandiose-manipulative, and impulsive-irresponsible dimensions of psychopathy are differentially related to various affective and physiological measures, assessed at baseline and in response to violent and erotic movie scenes. Data were collected from young adults (N = 101) at differential risk for psychopathic traits. Findings from regression analyses revealed a unique predictive contribution of grandiose-manipulative traits in particular to higher ratings of positive valence for violent scenes. Callous-unemotional traits were uniquely associated with lower levels of sympathy toward victims and lower ratings of fear and sadness during violent scenes. All three psychopathy dimensions and the total psychopathy scale showed negative zero-order correlations with heart rate at baseline, but regression analyses revealed that only grandiose manipulation was uniquely predictive of lower baseline heart rate. Grandiose manipulation was also significantly associated with lower baseline skin conductance. Regarding autonomic activity, findings resulted in a unique negative association between grandiose manipulation and heart rate activity in response to violent scenes. In contrast, the impulsive-irresponsible dimension was positively related with heart rate activity to violent scenes. Finally, findings revealed that only callous-unemotional traits were negatively associated with startle potentiation in response to violent scenes. No associations during erotic scenes were identified. These findings point to unique associations between the three assessed dimensions of psychopathy with physiological measures, indicating that grandiose manipulation is associated with hypoarousal, impulsive irresponsibility with hyperarousal, and callous-unemotional traits with low emotional and fear responses to violent scenes. © 2017 Society for Psychophysiological Research.

Examination of trait impulsivity on the response to a brief mindfulness intervention among college student drinkers

PubMed Central

Vinci, Christine; Peltier, MacKenzie; Waldo, Krystal; Kinsaul, Jessica; Shah, Sonia; Coffey, Scott F.; Copeland, Amy L.

2016-01-01

Mindfulness-based strategies show promise for targeting the construct of impulsivity and associated variables among problematic alcohol users. This study examined the moderating role of intervention (mindfulness vs relaxation vs control) on trait impulsivity and three outcomes examined post-intervention (negative affect, positive affect, and urge to drink) among 207 college students with levels of at-risk drinking. Moderation analyses revealed that the relationship between baseline impulsivity and the primary outcomes significantly differed for participants who underwent the mindfulness versus relaxation interventions. Notably, simple slope analyses revealed that negative urgency was positively associated with urge to drink following the mindfulness intervention. Among participants who underwent the relaxation intervention, analysis of simple slopes revealed that negative urgency was negatively associated with urge to drink, while positive urgency was positively associated with positive affect following the relaxation intervention. Findings suggest that level (low vs high) and subscale of impulsivity matter with regard to how a participant will respond to a mindfulness versus relaxation intervention. PMID:27344030

Human factors in cybersecurity; examining the link between Internet addiction, impulsivity, attitudes towards cybersecurity, and risky cybersecurity behaviours.

PubMed

Hadlington, Lee

2017-07-01

The present study explored the relationship between risky cybersecurity behaviours, attitudes towards cybersecurity in a business environment, Internet addiction, and impulsivity. 538 participants in part-time or full-time employment in the UK completed an online questionnaire, with responses from 515 being used in the data analysis. The survey included an attitude towards cybercrime and cybersecurity in business scale, a measure of impulsivity, Internet addiction and a 'risky' cybersecurity behaviours scale. The results demonstrated that Internet addiction was a significant predictor for risky cybersecurity behaviours. A positive attitude towards cybersecurity in business was negatively related to risky cybersecurity behaviours. Finally, the measure of impulsivity revealed that both attentional and motor impulsivity were both significant positive predictors of risky cybersecurity behaviours, with non-planning being a significant negative predictor. The results present a further step in understanding the individual differences that may govern good cybersecurity practices, highlighting the need to focus directly on more effective training and awareness mechanisms.

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.

Sensation Seeking and Online Gaming Addiction in Adolescents: A Moderated Mediation Model of Positive Affective Associations and Impulsivity.

PubMed

Hu, Jianping; Zhen, Shuangju; Yu, Chengfu; Zhang, Qiuyan; Zhang, Wei

2017-01-01

Based on the Dual Systems Model (Somerville et al., 2010; Steinberg, 2010a) and the biosocial-affect model (Romer and Hennessy, 2007) of adolescent sensation seeking and problem behaviors, the present study examined how (affective associations with online games as a mediator) and when (impulsivity as a moderator) did sensation seeking influence online gaming addiction in adolescence. A total of 375 Chinese male adolescents (mean age = 16.02 years, SD = 0.85) from southern China completed anonymous questionnaires regarding sensation seeking, positive affective associations with online games, impulsivity, and online gaming addiction. Our findings revealed that sensation seeking, positive affective associations with online games and impulsivity were each significantly and positively associated with online gaming addiction in adolescents. Positive affective associations mediated the relationship between sensation seeking and online gaming addiction. Further, impulsivity moderated the relationship between positive affective associations and online gaming addiction, such that the association between positive affective association and online gaming addiction was stronger for high than for low impulsivity adolescents. These findings underscore the importance of integrating the biosocial-affect model and the Dual Systems Model to understand how and when sensation seeking impacts adolescent online gaming addiction.

Sensation Seeking and Online Gaming Addiction in Adolescents: A Moderated Mediation Model of Positive Affective Associations and Impulsivity

PubMed Central

Hu, Jianping; Zhen, Shuangju; Yu, Chengfu; Zhang, Qiuyan; Zhang, Wei

2017-01-01

Based on the Dual Systems Model (Somerville et al., 2010; Steinberg, 2010a) and the biosocial-affect model (Romer and Hennessy, 2007) of adolescent sensation seeking and problem behaviors, the present study examined how (affective associations with online games as a mediator) and when (impulsivity as a moderator) did sensation seeking influence online gaming addiction in adolescence. A total of 375 Chinese male adolescents (mean age = 16.02 years, SD = 0.85) from southern China completed anonymous questionnaires regarding sensation seeking, positive affective associations with online games, impulsivity, and online gaming addiction. Our findings revealed that sensation seeking, positive affective associations with online games and impulsivity were each significantly and positively associated with online gaming addiction in adolescents. Positive affective associations mediated the relationship between sensation seeking and online gaming addiction. Further, impulsivity moderated the relationship between positive affective associations and online gaming addiction, such that the association between positive affective association and online gaming addiction was stronger for high than for low impulsivity adolescents. These findings underscore the importance of integrating the biosocial-affect model and the Dual Systems Model to understand how and when sensation seeking impacts adolescent online gaming addiction. PMID:28529494

Individual in Context: The Role of Impulse Control on the Association between the Home, School, and Neighborhood Developmental Contexts and Adolescent Delinquency.

PubMed

Fine, Adam; Mahler, Alissa; Steinberg, Laurence; Frick, Paul J; Cauffman, Elizabeth

2017-07-01

Social ecological theories and decades of supporting research suggest that contexts exert a powerful influence on adolescent delinquency. Individual traits, such as impulse control, also pose a developmental disadvantage to adolescents through increasing risk of delinquency. However, such individual differences may also predispose some youth to struggle more in adverse environments, but also to excel in enriched environments. Despite the prominence of impulse control in both developmental and criminological literatures, researchers are only beginning to consider impulse control as an individual characteristic that may affect developmental outcomes in response to environmental input. Using a racially diverse (Latino 46 %; Black 37 %; White 15 %; other race 2 %) sample of 1,216 first-time, male, juvenile offenders from the longitudinal Crossroads Study, this study examined key interactions between baseline impulse control and the home, school, and neighborhood contexts in relation to delinquency within the following 6 months. The results indicated that even after accounting for prior delinquency, youth in more negative home, school, and neighborhood contexts engaged in the same amount of delinquency in the following 6 months regardless of their level of impulse control. However, the effects of positive home, school, and neighborhood contexts on delinquency were stronger for youth with moderate or high impulse control and minimally affected youth with low impulse control. The findings suggest two risk factors for delinquency: low impulse control as a dispositional vulnerability that operates independently of developmental context, and a second that results from a contextual vulnerability.

Microwave emission from lead zirconate titanate induced by impulsive mechanical load

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

Aman, A., E-mail: alexander.aman@ovgu.de; Packaging Group, Institute of Micro- and Sensorsytems, Otto-von-Guericke University, Universitätsplatz 2, 39106 Magdeburg; Majcherek, S.

2015-10-28

This paper focuses on microwave emission from Lead zirconate titanate Pb [Zr{sub x}Ti{sub 1−x}] O{sub 3} (PZT) induced by mechanical stressing. The mechanical stress was initiated by impact of a sharp tungsten indenter on the upper surface of PZT ceramic. The sequences of microwave and current impulses, which flew from indenter to electric ground, were detected simultaneously. The voltage between the upper and lower surface of ceramic was measured to obtain the behavior of mechanical force acting on ceramic during the impact. It was found that the amplitude, form, and frequency of measured microwave impulses were different by compression andmore » restitution phase of impact. Two different mechanisms of electron emission, responsible for microwave impulse generation, were proposed based on the dissimilar impulse behavior. The field emission from tungsten indenter is dominant during compression, whereas ferroemission dominates during restitution phase. Indeed, it was observed that the direction of the current flow, i.e., sign of current impulses is changed by transitions from compression to restitution phase of impact. The observed dissimilar behavior of microwave impulses, caused by increasing and decreasing applied force, can be used to calculate the contact time and behavior of mechanical force during mechanical impact on ceramic surface. It is shown that the generation of microwave impulses exhibits high reproducibility, impulse intensity, a low damping factor, and high mechanical failure resistance. Based on these microwave emission properties of PZT, the development of new type of stress sensor with spatial resolution of few microns becomes possible.« less

Out-of-band and adjacent-channel interference reduction by analog nonlinear filters

NASA Astrophysics Data System (ADS)

Nikitin, Alexei V.; Davidchack, Ruslan L.; Smith, Jeffrey E.

2015-12-01

In a perfect world, we would have `brick wall' filters, no-distortion amplifiers and mixers, and well-coordinated spectrum operations. The real world, however, is prone to various types of unintentional and intentional interference of technogenic (man-made) origin that can disrupt critical communication systems. In this paper, we introduce a methodology for mitigating technogenic interference in communication channels by analog nonlinear filters, with an emphasis on the mitigation of out-of-band and adjacent-channel interference. Interference induced in a communications receiver by external transmitters can be viewed as wide-band non-Gaussian noise affecting a narrower-band signal of interest. This noise may contain a strong component within the receiver passband, which may dominate over the thermal noise. While the total wide-band interference seen by the receiver may or may not be impulsive, we demonstrate that the interfering component due to power emitted by the transmitter into the receiver channel is likely to appear impulsive under a wide range of conditions. We give an example of mechanisms of impulsive interference in digital communication systems resulting from the nonsmooth nature of any physically realizable modulation scheme for transmission of a digital (discontinuous) message. We show that impulsive interference can be effectively mitigated by nonlinear differential limiters (NDLs). An NDL can be configured to behave linearly when the input signal does not contain outliers. When outliers are encountered, the nonlinear response of the NDL limits the magnitude of the respective outliers in the output signal. The signal quality is improved in excess of that achievable by the respective linear filter, increasing the capacity of a communications channel. The behavior of an NDL, and its degree of nonlinearity, is controlled by a single parameter in a manner that enables significantly better overall suppression of the noise-containing impulsive components compared to the respective linear filter. Adaptive configurations of NDLs are similarly controlled by a single parameter and are suitable for improving quality of nonstationary signals under time-varying noise conditions. NDLs are designed to be fully compatible with existing linear devices and systems and to be used as an enhancement, or as a low-cost alternative, to the state-of-art interference mitigation methods.

Non-contact quantification of laser micro-impulse in water by atomic force microscopy and its application for biomechanics

NASA Astrophysics Data System (ADS)

Hosokawa, Yoichiroh

2011-12-01

We developed a local force measurement system of a femtosecond laser-induced impulsive force, which is due to shock and stress waves generated by focusing an intense femtosecond laser into water with a highly numerical aperture objective lens. In this system, the force localized in micron-sized region was detected by bending movement of a cantilever of atomic force microscope (AFM). Here we calculated the bending movement of the AFM cantilever when the femtosecond laser is focused in water at the vicinity of the cantilever and the impulsive force is loaded on the cantilever. From the result, a method to estimate the total of the impulsive force at the laser focal point was suggested and applied to estimate intercellular adhesion strength.

Making Professional Decisions in Research: Measurement and Key Predictors

PubMed Central

Antes, Alison L.; Chibnall, John T.; Baldwin, Kari A.; Tait, Raymond C.; Vander Wal, Jillon S.; DuBois, James M.

2016-01-01

The professional decision-making in research (PDR) measure was administered to 400 NIH-funded and industry-funded investigators, along with measures of cynicism, moral disengagement, compliance disengagement, impulsivity, work stressors, knowledge of responsible conduct of research (RCR), and socially desirable response tendencies. Negative associations were found for the PDR and measures of cynicism, moral disengagement, and compliance disengagement, while positive associations were found for the PDR and RCR knowledge and positive urgency, an impulsivity subscale. PDR scores were not related to socially desirable responding, or to measures of work stressors and the remaining impulsivity subscales. In a multivariate logistic regression analysis, lower moral disengagement scores, higher RCR knowledge, and identifying the United States as one’s nation of origin emerged as key predictors of stronger performance on the PDR. The implications of these findings for understanding the measurement of decision-making in research and future directions for research and RCR education are discussed. PMID:27093003

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

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.

Stabilization of time domain acoustic boundary element method for the interior problem with impedance boundary conditions.

PubMed

Jang, Hae-Won; Ih, Jeong-Guon

2012-04-01

The time domain boundary element method (BEM) is associated with numerical instability that typically stems from the time marching scheme. In this work, a formulation of time domain BEM is derived to deal with all types of boundary conditions adopting a multi-input, multi-output, infinite impulse response structure. The fitted frequency domain impedance data are converted into a time domain expression as a form of an infinite impulse response filter, which can also invoke a modeling error. In the calculation, the response at each time step is projected onto the wave vector space of natural radiation modes, which can be obtained from the eigensolutions of the single iterative matrix. To stabilize the computation, unstable oscillatory modes are nullified, and the same decay rate is used for two nonoscillatory modes. As a test example, a transient sound field within a partially lined, parallelepiped box is used, within which a point source is excited by an octave band impulse. In comparison with the results of the inverse Fourier transform of a frequency domain BEM, the average of relative difference norm in the stabilized time response is found to be 4.4%.

Altered intrinsic hippocmapus declarative memory network and its association with impulsivity in abstinent heroin dependent subjects.

PubMed

Zhai, Tian-Ye; Shao, Yong-Cong; Xie, Chun-Ming; Ye, En-Mao; Zou, Feng; Fu, Li-Ping; Li, Wen-Jun; Chen, Gang; Chen, Guang-Yu; Zhang, Zheng-Guo; Li, Shi-Jiang; Yang, Zheng

2014-10-01

Converging evidence suggests that addiction can be considered a disease of aberrant learning and memory with impulsive decision-making. In the past decades, numerous studies have demonstrated that drug addiction is involved in multiple memory systems such as classical conditioned drug memory, instrumental learning memory and the habitual learning memory. However, most of these studies have focused on the contributions of non-declarative memory, and declarative memory has largely been neglected in the research of addiction. Based on a recent finding that hippocampus, as a core functioning region of declarative memory, was proved biased the decision-making process based on past experiences by spreading associated reward values throughout memory. Our present study focused on the hippocampus. By utilizing seed-based network analysis on the resting-state functional MRI datasets with the seed hippocampus we tested how the intrinsic hippocampal memory network altered toward drug addiction, and examined how the functional connectivity strength within the altered hippocampal network correlated with behavioral index 'impulsivity'. Our results demonstrated that HD group showed enhanced coherence between hippocampus which represents declarative memory system and non-declarative reward-guided learning memory system, and also showed attenuated intrinsic functional link between hippocampus and top-down control system, compared to the CN group. This alteration was furthered found to have behavioral significance over the behavioral index 'impulsivity' measured with Barratt Impulsiveness Scale (BIS). These results provide insights into the mechanism of declarative memory underlying the impulsive behavior in drug addiction. Copyright © 2014 Elsevier B.V. All rights reserved.

Rash impulsiveness and reward sensitivity in relation to risky drinking by university students: potential roles of frontal systems.

PubMed

Lyvers, Michael; Duff, Helen; Basch, Vanessa; Edwards, Mark S

2012-08-01

Two forms of impulsivity, rash impulsiveness and reward sensitivity, have been proposed to reflect aspects of frontal lobe functioning and promote substance use. The present study examined these two forms of impulsivity as well as frontal lobe symptoms in relation to risky drinking by university students. University undergraduates aged 18-26years completed the Alcohol Use Disorders Identification Test (AUDIT), Barratt Impulsiveness Scale (BIS-11), Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ), Frontal Systems Behavior Scale (FrSBe), and a demographics questionnaire assessing age, gender, and age of onset of weekly drinking (AOD). AUDIT-defined harmful drinkers reported earlier AOD and scored higher on BIS-11, the Sensitivity to Reward (SR) scale of the SPSRQ, and the Disinhibition and Executive Dysfunction scales of the FrSBe compared to lower risk groups. Differences remained significant after controlling for duration of alcohol exposure. Path analyses indicated that the influence of SR on AUDIT was mediated by FrSBe Disinhibition, whereas the influence of BIS-11 on AUDIT was mediated by both Disinhibition and Executive Dysfunction scales of the FrSBe. Findings tentatively suggest that the influence of rash impulsiveness on drinking may reflect dysfunction in dorsolateral prefrontal and orbitofrontal systems, whereas the influence of reward sensitivity on drinking may primarily reflect orbitofrontal dysfunction. Irrespective of the underlying functional brain systems involved, results appear to be more consistent with a pre-drinking trait interpretation than effects of alcohol exposure. Copyright © 2012 Elsevier Ltd. All rights reserved.

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.

Tethered swimming can be used to evaluate force contribution for short-distance swimming performance.

PubMed

Morouço, Pedro G; Marinho, Daniel A; Keskinen, Kari L; Badillo, Juan J; Marques, Mário C

2014-11-01

The purpose of this study was two-fold: (a) to compare stroke and the physiological responses between maximal tethered and free front crawl swimming and (b) to evaluate the contribution of force exertion for swimming performance over short distances. A total of 34 male swimmers, representing various levels of competitive performance, participated in this study. Each participant was tested in both a 30-second maximal tethered swimming test and a 50-m free swimming test. The tethered force parameters, the swimming speed, stroke (stroke rate [SR]), and the physiological responses (increase in blood lactate concentration [ΔBLa], heart rate, and rate of perceived exertion) were recorded and calculated. The results showed no differences in stroke and the physiological responses between tethered and free swimming, with a high level of agreement for the SR and ΔBLa. A strong correlation was obtained between the maximum impulse of force per stroke and the speed (r = 0.91; p < 0.001). Multiple regression analysis revealed that the maximum impulse and SR in the tethered condition explained 84% of the free swimming performance. The relationship between the swimming speed and maximum force tended to be nonlinear, whereas linear relationships were observed with the maximum impulse. This study demonstrates that tethered swimming does not significantly alter stroke and the physiological responses compared with free swimming, and that the maximum impulse per stroke should be used to evaluate the balance between force and the ability to effectively apply force during sprint swimming. Consequently, coaches can rely on tethered forces to identify strength deficits and improve swimming performance over short distances.