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Sample records for discharge impulse image

  1. Micropower impulse radar imaging

    SciTech Connect

    Hall, M.S.

    1995-11-01

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

  2. Discharge current modes of high power impulse magnetron sputtering

    SciTech Connect

    Wu, Zhongzhen Xiao, Shu; Ma, Zhengyong; Cui, Suihan; Ji, Shunping; Pan, Feng; Tian, Xiubo; Fu, Ricky K. Y.; Chu, Paul K.

    2015-09-15

    Based on the production and disappearance of ions and electrons in the high power impulse magnetron sputtering plasma near the target, the expression of the discharge current is derived. Depending on the slope, six possible modes are deduced for the discharge current and the feasibility of each mode is discussed. The discharge parameters and target properties are simplified into the discharge voltage, sputtering yield, and ionization energy which mainly affect the discharge plasma. The relationship between these factors and the discharge current modes is also investigated.

  3. Effect of Lightning Impulse Discharge on PVC Thin Film

    NASA Astrophysics Data System (ADS)

    Takamura, Norimitsu; Matsumoto, Takao; Nerome, Hazuki; Mishima, Kenji; Izawa, Yasuji; Hanai, Masahiro; Nishijima, Kiyoto

    2015-09-01

    Lightning damage to blades of wind turbine generators has been increasing in parallel with the recent increase in the installation of the generators. According to a paper, it is said that a large current produced by a lightning penetrates into the blades, the air temperature and pressure inside the blades increase, which causes destruction of the blades. In order to solve this problem, preventing lightning penetration into the blades and passing lightning only on the surface of the blades are required. Therefore, we undertook a basic research for finding out the mechanism of lightning penetration into the blades. In this study, as our original research for clarifying the above mechanism, we investigated the effect of lightning impulse discharge on some polyvinyl chloride thin films. A high voltage electrode and a ground electrode were set with 1.0 m separation. Each film was set at the midpoint of the electrodes and approximately 750 kV of only one positive lightning impulse voltage was applied to the electrodes. After discharge, the hole-, deformed- and tarnished- diameters of the films, formed by discharge, were measured using a microscope. The results suggest that the thickness and/or the volume resistivity of the films are deeply tied to destruction of the films by discharge.

  4. Plasma potential mapping of high power impulse magnetron sputtering discharges

    SciTech Connect

    Rauch, Albert; Mendelsberg, Rueben J.; Sanders, Jason M.; Anders, Andre

    2011-12-20

    Pulsed emissive probe techniques have been used to determine the plasma potential distribution of high power impulse magnetron sputtering (HiPIMS) discharges. An unbalanced magnetron with a niobium target in argon was investigated for pulse length of 100 μs at a pulse repetition rate of 100 Hz, giving a peak current of 170 A. The probe data were taken with a time resolution of 20 ns and a spatial resolution of 1 mm. It is shown that the local plasma potential varies greatly in space and time. The lowest potential was found over the target’s racetrack, gradually reaching anode potential (ground) several centimeters away from the target. The magnetic pre-sheath exhibits a funnel-shaped plasma potential resulting in an electric field which accelerates ions toward the racetrack. In certain regions and times, the potential exhibits weak local maxima which allow for ion acceleration to the substrate. Knowledge of the local E and static B fields lets us derive the electrons’ E×B drift velocity, which is about 105 m/s and shows structures in space and time.

  5. Microscopic degradation mechanism of polyimide film caused by surface discharge under bipolar continuous square impulse voltage

    NASA Astrophysics Data System (ADS)

    Luo, Yang; Wu, Guang-Ning; Liu, Ji-Wu; Peng, Jia; Gao, Guo-Qiang; Zhu, Guang-Ya; Wang, Peng; Cao, Kai-Jiang

    2014-02-01

    Polyimide (PI) film is an important type of insulating material used in inverter-fed motors. Partial discharge (PD) under a sequence of high-frequency square impulses is one of the key factors that lead to premature failures in insulation systems of inverter-fed motors. In order to explore the damage mechanism of PI film caused by discharge, an aging system of surface discharge under bipolar continuous square impulse voltage (BCSIV) is designed based on the ASTM 2275 01 standard and the electrical aging tests of PI film samples are performed above the partial discharge inception voltage (PDIV). The chemical bonds of PI polymer chains are analyzed through Fourier transform infrared spectroscopy (FTIR) and the dielectric properties of unaged and aged PI samples are investigated by LCR testers HIOKI 3532-50. Finally, the micro-morphology and micro-structure changes of PI film samples are observed through scanning electron microscopy (SEM). The results show that the physical and chemical effects of discharge cut off the chemical bonds of PI polymer chains. The fractures of ether bond (C—O—C) and imide ring (C—N—C) on the backbone of a PI polymer chain leads to the decrease of molecular weight, which results in the degradation of PI polymers and the generation of new chemical groups and materials, like carboxylic acid, ketone, aldehydes, etc. The variation of microscopic structure of PI polymers can change the orientation ability of polarizable units when the samples are under an AC electric field, which would cause the dielectric constant ɛ to increase and dielectric loss tan δ to decrease. The SEM images show that the degradation path of PI film is initiated from the surface and then gradually extends to the interior with continuous aging. The injection charge could result in the PI macromolecular chain degradation and increase the trap density in the PI polymer bulk.

  6. Characterization of high power impulse magnetron sputtering discharges

    NASA Astrophysics Data System (ADS)

    Hala, Matej

    Paper I: In the first paper, we present a new approach in the characterization of the high power pulsed magnetron sputtering (HiPIMS) discharge evolution—time- and species-resolved plasma imaging—employing a set of band-pass optical interference filters suitable for the isolation of the emission originating from different species populating the plasma. We demonstrate that the introduction of such filters can be used to distinguish different phases of the discharge, and to visualize numerous plasma effects including background gas excitations during the discharge ignition, gas shock waves, and expansion of metal-rich plasmas. In particular, the application of this technique is shown on the diagnostics of the 200 µs long non-reactive HiPIMS discharges using a Cr target. Paper II: In order to gain further information about the dynamics of reactive HiPIMS discharges, both fast plasma imaging and time- and space-resolved optical emission spectroscopy (OES) are used for a systematic investigation of the 200 µs long HiPIMS pulses operated in Ar, N2 and N 2/Ar mixtures and at various pressures. It is observed that the dense metal plasma created next to the target propagates in the reactor at a speed ranging from 0.7 to 3.5 km s-1, depending on the working gas composition and the pressure. In fact, it increases with higher N 2 concentration and with lower pressure. The visible form of the propagating plasma wave changes from a hemispherical shape in Ar to a drop-like shape extending far from the target with increasing N2 concentration, owing to the significant emission from molecular N2. Interestingly, the evidence of the target self-sputtering is found for all investigated conditions, including pure N2 atmosphere. Paper III: Here, we report on the time- and species-resolved plasma imaging analysis of the dynamics of the 200 µs long HiPIMS discharges above a Cr target ignited in pure O2. It is shown that the discharge emission is dominated solely by neutral and

  7. Impulse Magnetic Fields Generated by Electrostatic Discharges in Protoplanetary Nebulae

    NASA Technical Reports Server (NTRS)

    Tunyi, I.; Guba, P.; Roth, L. E.; Timko, M.

    2002-01-01

    We examine quantitative aspects associated with the hypothesis of nebular lightnings as a source of impulse magnetic fields. Our findings support our previous accretion model in which a presence of impulse magnetic fields was of a key necessity. Additional information is contained in the original extended abstract.

  8. Investigation of high power impulse magnetron sputtering (HIPIMS) discharge using fast ICCD camera

    NASA Astrophysics Data System (ADS)

    Hecimovic, Ante

    2012-10-01

    High power impulse magnetron sputtering (HIPIMS) combines impulse glow discharges at power levels up to the MW range with conventional magnetron cathodes to achieve a highly ionised sputtered flux. The dynamics of the HIPIMS discharge was investigated using fast Intensified Charge Coupled Device (ICCD) camera. In the first experiment the HIPIMS plasma was recorded from the side with goal to analyse the plasma intensity using Abel inversion to obtain the emissivity maps of the plasma species. Resulting emissivity maps provide the information on the spatial distribution of Ar and sputtered material and evolution of the plasma chemistry above the cathode. In the second experiment the plasma emission was recorded with camera facing the target. The images show that the HIPIMS plasma develops drift wave type instabilities characterized by well defined regions of high and low plasma emissivity along the racetrack of the magnetron. The instabilities cause periodic shifts in the floating potential. The structures rotate in ExB direction at velocities of 10 kms-1 and frequencies up to 200 kHz. The high emissivity regions comprise Ar and metal ion emission with strong Ar and metal neutral emission depletion. A detailed analysis of the temporal evolution of the saturated instabilities using four consequently triggered fast ICCD cameras is presented. Furthermore working gas pressure and discharge current variation showed that the shape and the speed of the instability strongly depend on the working gas and target material combination. In order to better understand the mechanism of the instability, different optical interference band pass filters (of metal and gas atom, and ion lines) were used to observe the spatial distribution of each species within the instability.

  9. Transthoracic Cardiac Acoustic Radiation Force Impulse Imaging

    NASA Astrophysics Data System (ADS)

    Bradway, David Pierson

    This dissertation investigates the feasibility of a real-time transthoracic Acoustic Radiation Force Impulse (ARFI) imaging system to measure myocardial function non-invasively in clinical setting. Heart failure is an important cardiovascular disease and contributes to the leading cause of death for developed countries. Patients exhibiting heart failure with a low left ventricular ejection fraction (LVEF) can often be identified by clinicians, but patients with preserved LVEF might be undetected if they do not exhibit other signs and symptoms of heart failure. These cases motivate development of transthoracic ARFI imaging to aid the early diagnosis of the structural and functional heart abnormalities leading to heart failure. M-Mode ARFI imaging utilizes ultrasonic radiation force to displace tissue several micrometers in the direction of wave propagation. Conventional ultrasound tracks the response of the tissue to the force. This measurement is repeated rapidly at a location through the cardiac cycle, measuring timing and relative changes in myocardial stiffness. ARFI imaging was previously shown capable of measuring myocardial properties and function via invasive open-chest and intracardiac approaches. The prototype imaging system described in this dissertation is capable of rapid acquisition, processing, and display of ARFI images and shear wave elasticity imaging (SWEI) movies. Also presented is a rigorous safety analysis, including finite element method (FEM) simulations of tissue heating, hydrophone intensity and mechanical index (MI) measurements, and thermocouple transducer face heating measurements. For the pulse sequences used in later animal and clinical studies, results from the safety analysis indicates that transthoracic ARFI imaging can be safely applied at rates and levels realizable on the prototype ARFI imaging system. Preliminary data are presented from in vivo trials studying changes in myocardial stiffness occurring under normal and abnormal

  10. Measurement of the impulse produced by a pulsed surface discharge actuator in air

    NASA Astrophysics Data System (ADS)

    Elias, P. Q.; Castera, P.

    2013-09-01

    The pulsed surface discharge in atmospheric pressure air generates a shock wave, thereby transferring an impulse to the surrounding gas. The aim of this work is to measure this impulse, using implementation of a plasma actuator based on linear surface discharges of length up to 10 cm, and of linear energy in a range 0.1-0.5 J cm-1. The shock wave generated by the discharge is visualized using a pulsed schlieren system and the impulse is measured with a dedicated balance. These measurements are correlated with 1D numerical simulations of pulsed energy depositions in a perfect gas. Experiments show that the discharge generates a cylindrical shock wave that travels at sonic speed after a few tens of microseconds, and produces an impulse that varies from 1 to 4 mN s m-1 and scales linearly with the linear energy density. This linearity agrees with the numerical simulations when 9.5% of the energy dissipated in the discharge is assumed to heat the gas. Overall, to produce a time-averaged force similar to the one achieved by dielectric barrier discharge (DBD) actuators, 2 to 3 times more power is required. However, surface discharge actuators do not saturate, and thus can induce time-averaged forces one or two orders of magnitude above DBD when pulsed at several hundreds of hertz.

  11. On the electron energy in the high power impulse magnetron sputtering discharge

    SciTech Connect

    Gudmundsson, J. T.; Sigurjonsson, P.; Larsson, P.; Lundin, D.; Helmersson, U.

    2009-06-15

    The temporal variation of the electron energy distribution function (EEDF) was measured with a Langmuir probe in a high power impulse magnetron sputtering (HiPIMS) discharge at 3 and 20 mTorr pressures. In the HiPIMS discharge a high power pulse is applied to a planar magnetron giving a high electron density and highly ionized sputtered vapor. The measured EEDF is Maxwellian-like during the pulse; it is broader for lower discharge pressure and it becomes narrower as the pulse progresses. This indicates that the plasma cools as the pulse progresses, probably due to high metal content of the discharge.

  12. Discharge Physics of High Power Impulse Magnetron Sputtering

    SciTech Connect

    Anders, Andre

    2010-10-13

    High power impulse magnetron sputtering (HIPIMS) is pulsed sputtering where the peak power exceeds the time-averaged power by typically two orders of magnitude. The peak power density, averaged over the target area, can reach or exceed 107 W/m2, leading to plasma conditions that make ionization of the sputtered atoms very likely. A brief review of HIPIMS operation is given in a tutorial manner, illustrated by some original data related to the self-sputtering of niobium in argon and krypton. Emphasis is put on the current-voltage-time relationships near the threshold of self-sputtering runaway. The great variety of current pulse shapes delivers clues on the very strong gas rarefaction, self-sputtering runaway conditions, and the stopping of runaway due to the evolution of atom ionization and ion return probabilities as the gas plasma is replaced by metal plasma. The discussions are completed by considering instabilities and the special case of ?gasless? self-sputtering.

  13. Are the argon metastables important in high power impulse magnetron sputtering discharges?

    SciTech Connect

    Gudmundsson, J. T.; Lundin, D.; Minea, T. M.; Stancu, G. D.; Brenning, N.

    2015-11-15

    We use an ionization region model to explore the ionization processes in the high power impulse magnetron sputtering (HiPIMS) discharge in argon with a titanium target. In conventional dc magnetron sputtering (dcMS), stepwise ionization can be an important route for ionization of the argon gas. However, in the HiPIMS discharge stepwise ionization is found to be negligible during the breakdown phase of the HiPIMS pulse and becomes significant (but never dominating) only later in the pulse. For the sputtered species, Penning ionization can be a significant ionization mechanism in the dcMS discharges, while in the HiPIMS discharge Penning ionization is always negligible as compared to electron impact ionization. The main reasons for these differences are a higher plasma density in the HiPIMS discharge, and a higher electron temperature. Furthermore, we explore the ionization fraction and the ionized flux fraction of the sputtered vapor and compare with recent experimental work.

  14. Acoustic Radiation Force Impulse (ARFI) Imaging: a Review

    PubMed Central

    Nightingale, Kathy

    2012-01-01

    Acoustic radiation force based elasticity imaging methods are under investigation by many groups. These methods differ from traditional ultrasonic elasticity imaging methods in that they do not require compression of the transducer, and are thus expected to be less operator dependent. Methods have been developed that utilize impulsive (i.e. < 1 ms), harmonic (pulsed), and steady state radiation force excitations. The work discussed herein utilizes impulsive methods, for which two imaging approaches have been pursued: 1) monitoring the tissue response within the radiation force region of excitation (ROE) and generating images of relative differences in tissue stiffness (Acoustic Radiation Force Impulse (ARFI) imaging); and 2) monitoring the speed of shear wave propagation away from the ROE to quantify tissue stiffness (Shear Wave Elasticity Imaging (SWEI)). For these methods, a single ultrasound transducer on a commercial ultrasound system can be used to both generate acoustic radiation force in tissue, and to monitor the tissue displacement response. The response of tissue to this transient excitation is complicated and depends upon tissue geometry, radiation force field geometry, and tissue mechanical and acoustic properties. Higher shear wave speeds and smaller displacements are associated with stiffer tissues, and slower shear wave speeds and larger displacements occur with more compliant tissues. ARFI images have spatial resolution comparable to that of B-mode, often with greater contrast, providing matched, adjunctive information. SWEI images provide quantitative information about the tissue stiffness, typically with lower spatial resolution. A review these methods and examples of clinical applications are presented herein. PMID:22545033

  15. Quenching electron runaway in positive high-voltage-impulse discharges in air by laser filaments.

    PubMed

    Eto, S; Zhidkov, A; Oishi, Y; Miki, M; Fujii, T

    2012-03-15

    Strong hard (ε>100 keV) x rays being observed from impulse atmospheric discharges with maximal voltages from U=0.5 to 0.9 MV just before the breakdown were completely stopped with the use of femtosecond-laser-filament plasma. Runaway electrons generating such x rays and being estimated to achieve their maximal energy, ε~U, near the positive electrode disappear if a laser filament plasma is ignited perpendicularly to the runaway near the positive electrode. A preheating mechanism for formation of the electron runaway in air is proposed.

  16. Investigation of ionized metal flux in enhanced high power impulse magnetron sputtering discharges

    SciTech Connect

    Stranak, Vitezslav; Hubicka, Zdenek; Cada, Martin; Drache, Steffen; Hippler, Rainer; Tichy, Milan

    2014-04-21

    The metal ionized flux fraction and production of double charged metal ions Me{sup 2+} of different materials (Al, Cu, Fe, Ti) by High Power Impulse Magnetron Sputtering (HiPIMS) operated with and without a pre-ionization assistance is compared in the paper. The Electron Cyclotron Wave Resonance (ECWR) discharge was employed as the pre-ionization agent providing a seed of charge in the idle time of HiPIMS pulses. A modified grid-free biased quartz crystal microbalance was used to estimate the metal ionized flux fraction ξ. The energy-resolved mass spectrometry served as a complementary method to distinguish particular ion contributions to the total ionized flux onto the substrate. The ratio between densities of doubly Me{sup 2+} and singly Me{sup +} charged metal ions was determined. It is shown that ECWR assistance enhances Me{sup 2+} production with respect of absorbed rf-power. The ECWR discharge also increases the metal ionized flux fraction of about 30% especially in the region of lower pressures. Further, the suppression of the gas rarefaction effect due to enhanced secondary electron emission of Me{sup 2+} was observed.

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

    PubMed Central

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

    2011-01-01

    Ultrasound-guided needle placement is widely used in the clinical setting, particularly for central venous catheter placement, tissue biopsy and regional anesthesia. Difficulties with ultrasound guidance in these areas often result from steep needle insertion angles and spatial offsets between the imaging plane and the needle. Acoustic Radiation Force Impulse (ARFI) imaging leads to improved needle visualization because it uses a standard diagnostic scanner to perform radiation force based elasticity imaging, creating a displacement map that displays tissue stiffness variations. The needle visualization in ARFI images is independent of needle-insertion angle and also extends needle visibility out of plane. Although ARFI images portray needles well, they often do not contain the usual B-mode landmarks. Therefore, a three-step segmentation algorithm has been developed to identify a needle in an ARFI image and overlay the needle prediction on a coregistered B-mode image. The steps are: (1) contrast enhancement by median filtration and Laplacian operator filtration, (2) noise suppression through displacement estimate correlation coefficient thresholding and (3) smoothing by removal of outliers and best-fit line prediction. The algorithm was applied to data sets from horizontal 18, 21 and 25 gauge needles between 0–4 mm offset in elevation from the transducer imaging plane and to 18G needles on the transducer axis (in plane) between 10° and 35° from the horizontal. Needle tips were visualized within 2 mm of their actual position for both horizontal needle orientations up to 1.5 mm off set in elevation from the transducer imaging plane and on-axis angled needles between 10°–35° above the horizontal orientation. We conclude that segmented ARFI images overlaid on matched B-mode images hold promise for improved needle visibility in many clinical applications. PMID:21608445

  18. Landmine detection and imaging using Micropower Impulse Radar (MIR)

    SciTech Connect

    Azevedo, S.G.; Gravel, D.T.; Mast, J.E.; Warhus, J.P.

    1995-08-07

    The Lawrence Livermore National Laboratory (LLNL) has developed radar and imaging technologies with potential applications in mine detection by the armed forces and other agencies involved in determining efforts. These new technologies use a patented ultra-wideband (impulse) radar technology that is compact, low-cost, and low power. Designated as Micropower hnpulse Radar, these compact, self-contained radars can easily be assembled into arrays to form complete ground penetrating radar imaging systems. LLNL has also developed tomographic reconstruction and signal processing software capable of producing high-resolution 2-D and 3-D images of objects buried in materials like soil or concrete from radar data. Preliminary test results have shown that a radar imaging system using these technologies has the ability to image both metallic and plastic land mine surrogate targets buried in 5 to 10 cm of moist soil. In dry soil, the system can detect buried objects to a depth of 30 cm and more. This report describes our initial test results and plans for future work.

  19. Free segmentation in rendered 3D images through synthetic impulse response in integral imaging

    NASA Astrophysics Data System (ADS)

    Martínez-Corral, M.; Llavador, A.; Sánchez-Ortiga, E.; Saavedra, G.; Javidi, B.

    2016-06-01

    Integral Imaging is a technique that has the capability of providing not only the spatial, but also the angular information of three-dimensional (3D) scenes. Some important applications are the 3D display and digital post-processing as for example, depth-reconstruction from integral images. In this contribution we propose a new reconstruction method that takes into account the integral image and a simplified version of the impulse response function (IRF) of the integral imaging (InI) system to perform a two-dimensional (2D) deconvolution. The IRF of an InI system has a periodic structure that depends directly on the axial position of the object. Considering different periods of the IRFs we recover by deconvolution the depth information of the 3D scene. An advantage of our method is that it is possible to obtain nonconventional reconstructions by considering alternative synthetic impulse responses. Our experiments show the feasibility of the proposed method.

  20. Identifying Vulnerable Plaques with Acoustic Radiation Force Impulse Imaging

    NASA Astrophysics Data System (ADS)

    Doherty, Joshua Ryan

    The rupture of arterial plaques is the most common cause of ischemic complications including stroke, the fourth leading cause of death and number one cause of long term disability in the United States. Unfortunately, because conventional diagnostic tools fail to identify plaques that confer the highest risk, often a disabling stroke and/or sudden death is the first sign of disease. A diagnostic method capable of characterizing plaque vulnerability would likely enhance the predictive ability and ultimately the treatment of stroke before the onset of clinical events. This dissertation evaluates the hypothesis that Acoustic Radiation Force Impulse (ARFI) imaging can noninvasively identify lipid regions, that have been shown to increase a plaque's propensity to rupture, within carotid artery plaques in vivo. The work detailed herein describes development efforts and results from simulations and experiments that were performed to evaluate this hypothesis. To first demonstrate feasibility and evaluate potential safety concerns, finite- element method simulations are used to model the response of carotid artery plaques to an acoustic radiation force excitation. Lipid pool visualization is shown to vary as a function of lipid pool geometry and stiffness. A comparison of the resulting Von Mises stresses indicates that stresses induced by an ARFI excitation are three orders of magnitude lower than those induced by blood pressure. This thesis also presents the development of a novel pulse inversion harmonic tracking method to reduce clutter-imposed errors in ultrasound-based tissue displacement estimates. This method is validated in phantoms and was found to reduce bias and jitter displacement errors for a marked improvement in image quality in vivo. Lastly, this dissertation presents results from a preliminary in vivo study that compares ARFI imaging derived plaque stiffness with spatially registered composition determined by a Magnetic Resonance Imaging (MRI) gold standard

  1. Time-lag properties of corona streamer discharges between impulse sphere and dc needle electrodes under atmospheric air conditions

    NASA Astrophysics Data System (ADS)

    Okano, Daisuke

    2013-02-01

    In this study of corona streamer discharges from an impulse generator using a dc power supply, the relationship of the discharge time-lag with the dc bias voltage between the sphere-to-needle electrodes under atmospheric conditions is investigated. Devices utilizing corona discharges have been used to purify air or water, destroy bacteria, and to remove undesirable substances, and in order to achieve fast response times and high power efficiencies in such devices, it is important to minimize the time-lag of the corona discharge. Our experimental results show that (a) the discharge path of a negatively biased needle electrode will be straighter than that of a positively biased needle and (b) the discharge threshold voltage in both the positive and the negative needle electrodes is nearly equal to 33 kV. By expressing the discharge voltage as a power function of time-lag, the extent of corona generation can be quantitatively specified using the exponent of this power function. The observed behavior of a corona streamer discharge between the negative spherical and the positive needle electrodes indicates that the largest power exponent is associated with the shortest time-lag, owing to the reduction in the statistical time-lag in the absence of a formative time-lag.

  2. Impulse radar imaging system for concealed object detection

    NASA Astrophysics Data System (ADS)

    Podd, F. J. W.; David, M.; Iqbal, G.; Hussain, F.; Morris, D.; Osakue, E.; Yeow, Y.; Zahir, S.; Armitage, D. W.; Peyton, A. J.

    2013-10-01

    Electromagnetic systems for imaging concealed objects at checkpoints typically employ radiation at millimetre and terahertz frequencies. These systems have been shown to be effective and provide a sufficiently high resolution image. However there are difficulties and current electromagnetic systems have limitations particularly in accurately differentiating between threat and innocuous objects based on shape, surface emissivity or reflectivity, which are indicative parameters. In addition, water has a high absorption coefficient at millimetre wavelength and terahertz frequencies, which makes it more difficult for these frequencies to image through thick damp clothing. This paper considers the potential of using ultra wideband (UWB) in the low gigahertz range. The application of this frequency band to security screening appears to be a relatively new field. The business case for implementing the UWB system has been made financially viable by the recent availability of low-cost integrated circuits operating at these frequencies. Although designed for the communication sector, these devices can perform the required UWB radar measurements as well. This paper reports the implementation of a 2 to 5 GHz bandwidth linear array scanner. The paper describes the design and fabrication of transmitter and receiver antenna arrays whose individual elements are a type of antipodal Vivaldi antenna. The antenna's frequency and angular response were simulated in CST Microwave Studio and compared with laboratory measurements. The data pre-processing methods of background subtraction and deconvolution are implemented to improve the image quality. The background subtraction method uses a reference dataset to remove antenna crosstalk and room reflections from the dataset. The deconvolution method uses a Wiener filter to "sharpen" the returned echoes which improves the resolution of the reconstructed image. The filter uses an impulse response reference dataset and a signal

  3. Liver reserve function assessment by acoustic radiation force impulse imaging

    PubMed Central

    Sun, Xiao-Lan; Liang, Li-Wei; Cao, Hui; Men, Qiong; Hou, Ke-Zhu; Chen, Zhen; Zhao, Ya-E

    2015-01-01

    AIM: To evaluate the utility of liver reserve function by acoustic radiation force impulse (ARFI) imaging in patients with liver tumors. METHODS: Seventy-six patients with liver tumors were enrolled in this study. Serum biochemical indexes, such as aminotransferase (ALT), aspartate aminotransferase (AST), serum albumin (ALB), total bilirubin (T-Bil), and other indicators were observed. Liver stiffness (LS) was measured by ARFI imaging, measurements were repeated 10 times, and the average value of the results was taken as the final LS value. Indocyanine green (ICG) retention was performed, and ICG-K and ICG-R15 were recorded. Child-Pugh (CP) scores were carried out based on patient’s preoperative biochemical tests and physical condition. Correlations among CP scores, ICG-R15, ICG-K and LS values were observed and analyzed using either the Pearson correlation coefficient or the Spearman rank correlation coefficient. Kruskal-Wallis test was used to compare LS values of CP scores, and the receiver-operator characteristic (ROC) curve was used to analyze liver reserve function assessment accuracy. RESULTS: LS in the ICG-R15 10%-20% group was significantly higher than in the ICG-R15 < 10% group; and the difference was statistically significant (2.19 ± 0.27 vs 1.59 ± 0.32, P < 0.01). LS in the ICG-R15 > 20% group was significantly higher than in the ICG-R15 < 10% group; and the difference was statistically significant (2.92 ± 0.29 vs 1.59 ± 0.32, P < 0.01). The LS value in patients with CP class A was lower than in patients with CP class B (1.57 ± 0.34 vs 1.86 ± 0.27, P < 0.05), while the LS value in patients with CP class B was lower than in patients with CP class C (1.86 ± 0.27 vs 2.47 ± 0.33, P < 0.01). LS was positively correlated with ICG-R15 (r = 0.617, P < 0.01) and CP score (r = 0.772, P < 0.01). Meanwhile, LS was negatively correlated with ICG-K (r = -0.673, P < 0.01). AST, ALT and T-Bil were positively correlated with LS, while ALB was negatively

  4. Image modulation in corona discharge photography.

    PubMed

    Pehek, J O; Kyler, H J; Faust, D L

    1976-10-15

    Photographic images obtained by the Kirlian technique are principally a record of corona activity during an exposure interval. Most of the variations in the images of the corona of a living subject who is in contact with the photographic film can be accounted for by the presence of moisture on or within the subject's surface. During exposure, moisture is transferred from the subject to the emulsion surface of the photographic film and causes an alteration of the electric charge pattern on the film, hence the electric field at the surface of the subject. As a result, large variations in the density of corona images, corona streamer trajectories, and image coloration can be brought about. The radial extent of corona images--that is, the range of corona streamers--is an inverse function of the resistance in the circuit formed by the high-voltage supply, the subject, and the film-electrode configuration. This is because the voltage at which corona is initiated is dependent on the rate of rise of the voltage impressed between the subject and the electrode, and the rate of rise is governed by the applied voltage waveform and the voltage drop across the resistance. The range of streamers is proportional to the corona onset voltage. However, we have not seen any influence of large changes in skin resistance on streamer range. Presumably, this is due to the shunting effect of skin capacitance. In general, the photographic response to moisture suggests that corona discharge photography may be useful in the detection and quantification of moisture in animate and inanimate specimens through the orderly modulation of the image due to various levels of moisture. PMID:968480

  5. High power impulse magnetron sputtering discharges: Instabilities and plasma self-organization

    SciTech Connect

    Ehiasarian, A. P.; New, R.; Hecimovic, A.; Arcos, T. de los; Schulz-von der Gathen, V.; Boeke, M.; Winter, J.

    2012-03-12

    We report on instabilities in high power impulse magnetron sputtering plasmas which are likely to be of the generalized drift wave type. They are characterized by well defined regions of high and low plasma emissivity along the racetrack of the magnetron and cause periodic shifts in floating potential. The azimuthal mode number m depends on plasma current, plasma density, and gas pressure. The structures rotate in E-vectorxB-vector direction at velocities of {approx}10 km s{sup -1} and frequencies up to 200 kHz. Collisions with residual gas atoms slow down the rotating wave, whereas increasing ionization degree of the gas and plasma conductivity speeds it up.

  6. Alfven's critical ionization velocity observed in high power impulse magnetron sputtering discharges

    SciTech Connect

    Brenning, N.; Lundin, D.

    2012-09-15

    Azimuthally rotating dense plasma structures, spokes, have recently been detected in several high power impulse magnetron sputtering (HiPIMS) devices used for thin film deposition and surface treatment, and are thought to be important for plasma buildup, energizing of electrons, as well as cross-B transport of charged particles. In this work, the drift velocities of these spokes are shown to be strongly correlated with the critical ionization velocity, CIV, proposed by Alfven. It is proposed as the most promising approach in combining the CIV and HiPIMS research fields is to focus on the role of spokes in the process of electron energization.

  7. A new efficient approach for the removal of impulse noise from highly corrupted images.

    PubMed

    Abreu, E; Lightstone, M; Mitra, S K; Arakawa, K

    1996-01-01

    A new framework for removing impulse noise from images is presented in which the nature of the filtering operation is conditioned on a state variable defined as the output of a classifier that operates on the differences between the input pixel and the remaining rank-ordered pixels in a sliding window. As part of this framework, several algorithms are examined, each of which is applicable to fixed and random-valued impulse noise models. First, a simple two-state approach is described in which the algorithm switches between the output of an identity filter and a rank-ordered mean (ROM) filter. The technique achieves an excellent tradeoff between noise suppression and detail preservation with little increase in computational complexity over the simple median filter. For a small additional cost in memory, this simple strategy is easily generalized into a multistate approach using weighted combinations of the identity and ROM filter in which the weighting coefficients can be optimized using image training data. Extensive simulations indicate that these methods perform significantly better in terms of noise suppression and detail preservation than a number of existing nonlinear techniques with as much as 40% impulse noise corruption. Moreover, the method can effectively restore images corrupted with Gaussian noise and mixed Gaussian and impulse noise. Finally, the method is shown to be extremely robust with respect to the training data and the percentage of impulse noise. PMID:18285188

  8. A new efficient approach for the removal of impulse noise from highly corrupted images.

    PubMed

    Abreu, E; Lightstone, M; Mitra, S K; Arakawa, K

    1996-01-01

    A new framework for removing impulse noise from images is presented in which the nature of the filtering operation is conditioned on a state variable defined as the output of a classifier that operates on the differences between the input pixel and the remaining rank-ordered pixels in a sliding window. As part of this framework, several algorithms are examined, each of which is applicable to fixed and random-valued impulse noise models. First, a simple two-state approach is described in which the algorithm switches between the output of an identity filter and a rank-ordered mean (ROM) filter. The technique achieves an excellent tradeoff between noise suppression and detail preservation with little increase in computational complexity over the simple median filter. For a small additional cost in memory, this simple strategy is easily generalized into a multistate approach using weighted combinations of the identity and ROM filter in which the weighting coefficients can be optimized using image training data. Extensive simulations indicate that these methods perform significantly better in terms of noise suppression and detail preservation than a number of existing nonlinear techniques with as much as 40% impulse noise corruption. Moreover, the method can effectively restore images corrupted with Gaussian noise and mixed Gaussian and impulse noise. Finally, the method is shown to be extremely robust with respect to the training data and the percentage of impulse noise.

  9. Magnetic resonance imaging structural alterations in brain of alcohol abusers and its association with impulsivity.

    PubMed

    Asensio, Samuel; Morales, Julia L; Senabre, Isabel; Romero, Maria J; Beltran, Miguel A; Flores-Bellver, Miguel; Barcia, Jorge M; Romero, Francisco J

    2016-07-01

    Despite the suggestion that impulsivity plays a central role in the transfer from a recreational drug use to a substance use disorder, very few studies focused on neurobiological markers for addiction. This study aimed to identify volumetric alterations in a sample of patients with mild alcohol use disorder with a short history of alcohol use, compared with a control group, and also focused on its association with impulsivity levels. Most magnetic resonance imaging studies have focused on severe alcohol use disorder, formerly called alcohol-dependent patients, showing alcohol-related structural alterations and their association with alcohol use history variables but not with personality parameters like impulsivity. Our hypothesis is that our group of alcohol users may already display structural alterations especially in brain regions related to inhibitory control like medial-prefrontal regions, and that those structural alterations could be more associated to personality traits like impulsivity than to drug use variables. Our results clearly demonstrate that our population showed lower regional grey and white matter volumes in the medial-prefrontal and orbitofrontal cortices, as well as higher regional white matter volume in the ventral striatum and the internal capsule. Volumetric alterations were associated to the Barratt's impulsivity score: the more impulsive the subjects, the lower the medial-prefrontal cortex grey matter volume.

  10. The Image of Teachers: The Perception of Others as Impulses for the Professionalisation of Teaching

    ERIC Educational Resources Information Center

    Grunder, Hans-Ulrich

    2016-01-01

    This article describes the images of teachers as constructs of a public interest in education and schools. It uses the portrayals of teachers as a productive impulse to reflect on what the professionalisation of teaching practice in schools and classrooms could imply, in particular focusing on the characteristics of accomplished teachers and poor…

  11. Volume-surface barrier discharge in dried air in three-electrode system fed by impulse high voltage with nanosecond rise time

    NASA Astrophysics Data System (ADS)

    Malashin, Maxim; Rebrov, Igor; Nebogatkin, Sergey; Sokolova, Marina; Nikitin, Alexey; Voevodin, Vadim; Krivov, Sergey

    2016-08-01

    Results of experimental investigation of a volume-surface barrier discharge in a three-electrode system under periodic impulse voltage applied to the surface discharge (SD) electrodes and a d.c. potential applied to an additional third electrode are presented. It is shown that there is a strong influence of polarity and amplitude of the d.c. potential on the direct current "extracted" out of the surface discharge plasma layer by electric field of the third electrode. The amount of charged positive species that constitute the "extracted" current prevails under positive impulse voltage for low values of the negative d.c. potential of the third electrode. The amount of negative species prevails with higher values of the positive d.c. positive of the third electrode. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  12. Speckle reduction in optical coherence tomography images via dynamic infinite-impulse-response filtering

    NASA Astrophysics Data System (ADS)

    Lee, Jun; Park, Sangshik; Chung, Jung-Ho

    2014-03-01

    A temporal filtering method based on an infinite-impulse-response filter is presented to reduce speckle in optical coherence tomography (OCT) images. This method works in a recursive way, linearly combining the current B-scan image frame with a previously filtered one to generate a newly filtered image. Thus, it performs with less computational complexity and time, compared to the finite-impulse-response filter based approach that typically averages multiple stored frames. To achieve speckle noise reduction while avoiding image blurring caused by sample motion, the filter coefficient is dynamically determined, depending on the parameters related to motion detection and image quality. We used the mean-squared error (MSE) between two successive frames as a criterion to detect sample motion and changed the filter coefficient when the MSE exceeded a certain threshold to prevent image blurring. The optimal coefficient and motion detection threshold were chosen for achieving robust and unblurred images in our testbed configuration. In this study, we analyzed the algorithm with OCT images acquired by a swept-source OCT system we built and also examined that the method operated in real-time even via CPU processing. Results in our and conventional schemes are compared by using various image quality metrics and by observing images. We found that the performance of speckle reduction was quite promising and simultaneously the fine details of sample structures were preserved even with sample motion.

  13. Dielectric barrier discharge image processing by Photoshop

    NASA Astrophysics Data System (ADS)

    Dong, Lifang; Li, Xuechen; Yin, Zengqian; Zhang, Qingli

    2001-09-01

    In this paper, the filamentary pattern of dielectric barrier discharge has been processed by using Photoshop, the coordinates of each filament can also be obtained. By using Photoshop two different ways have been used to analyze the spatial order of the pattern formation in dielectric barrier discharge. The results show that the distance of the neighbor filaments at U equals 14 kV and d equals 0.9 mm is about 1.8 mm. In the scope of the experimental error, the results from the two different methods are similar.

  14. Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas

    SciTech Connect

    Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore; Andersson, Joakim; Ni, Pavel; Anders, Andre

    2013-07-17

    Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

  15. High-speed imaging system for observation of discharge phenomena

    NASA Astrophysics Data System (ADS)

    Tanabe, R.; Kusano, H.; Ito, Y.

    2008-11-01

    A thin metal electrode tip instantly changes its shape into a sphere or a needlelike shape in a single electrical discharge of high current. These changes occur within several hundred microseconds. To observe these high-speed phenomena in a single discharge, an imaging system using a high-speed video camera and a high repetition rate pulse laser was constructed. A nanosecond laser, the wavelength of which was 532 nm, was used as the illuminating source of a newly developed high-speed video camera, HPV-1. The time resolution of our system was determined by the laser pulse width and was about 80 nanoseconds. The system can take one hundred pictures at 16- or 64-microsecond intervals in a single discharge event. A band-pass filter at 532 nm was placed in front of the camera to block the emission of the discharge arc at other wavelengths. Therefore, clear images of the electrode were recorded even during the discharge. If the laser was not used, only images of plasma during discharge and thermal radiation from the electrode after discharge were observed. These results demonstrate that the combination of a high repetition rate and a short pulse laser with a high speed video camera provides a unique and powerful method for high speed imaging.

  16. Impulse Response Estimation for Spatial Resolution Enhancement in Ultrasonic NDE Imaging

    SciTech Connect

    Clark, G A

    2004-06-25

    This report describes a signal processing algorithm and MATLAB software for improving spatial resolution in ultrasonic nondestructive evaluation (NDE) imaging of materials. Given a measured reflection signal and an associated reference signal, the algorithm produces an optimal least-squares estimate of the impulse response of the material under test. This estimated impulse response, when used in place of the raw reflection signal, enhances the spatial resolution of the ultrasonic measurements by removing distortion caused by the limited-bandwidth transducers and the materials under test. The theory behind the processing algorithms is briefly presented, while the reader is referred to the bibliography for details. The main focus of the report is to describe how to use the MATLAB software. Two processing examples using actual ultrasonic measurements are provided for tutorial purposes.

  17. Statement of capabilities: Micropower Impulse Radar (MIR) technology applied to mine detection and imaging

    SciTech Connect

    Azevedo, S.G.; Gavel, D.T.; Mast, J.E.; Warhus, J.P.

    1995-03-13

    The Lawrence Livermore National Laboratory (LLNL) has developed radar and imaging technologies with potential applications in mine detection by the armed forces and other agencies involved in demining efforts. These new technologies use a patented ultra-wideband (impulse) radar technology that is compact, low-cost, and low power. Designated as Micropower Impulse Radar, these compact, self-contained radars can easily be assembled into arrays to form complete ground penetrating radar imaging systems. LLNL has also developed tomographic reconstruction and signal processing software capable of producing high-resolution 2-D and 3-D images of objects buried in materials like soil or concrete from radar data. Preliminary test results have shown that a radar imaging system using these technologies has the ability to image both metallic and plastic land mine surrogate targets buried in 5 to 10 cm of moist soil. In dry soil, the system can detect buried objects to a depth of 30 cm and more. This report describes LLNL`s unique capabilities and technologies that can be applied to the demining problem.

  18. Adaptive correction procedure for TVL1 image deblurring under impulse noise

    NASA Astrophysics Data System (ADS)

    Bai, Minru; Zhang, Xiongjun; Shao, Qianqian

    2016-08-01

    For the problem of image restoration of observed images corrupted by blur and impulse noise, the widely used TVL1 model may deviate from both the data-acquisition model and the prior model, especially for high noise levels. In order to seek a solution of high recovery quality beyond the reach of the TVL1 model, we propose an adaptive correction procedure for TVL1 image deblurring under impulse noise. Then, a proximal alternating direction method of multipliers (ADMM) is presented to solve the corrected TVL1 model and its convergence is also established under very mild conditions. It is verified by numerical experiments that our proposed approach outperforms the TVL1 model in terms of signal-to-noise ratio (SNR) values and visual quality, especially for high noise levels: it can handle salt-and-pepper noise as high as 90% and random-valued noise as high as 70%. In addition, a comparison with a state-of-the-art method, the two-phase method, demonstrates the superiority of the proposed approach.

  19. An efficient two-phase L(1)-TV method for restoring blurred images with impulse noise.

    PubMed

    Chan, Raymond H; Dong, Yiqiu; Hintermüller, Michael

    2010-07-01

    A two-phase image restoration method based upon total variation regularization combined with an L(1)-data-fitting term for impulse noise removal and deblurring is proposed. In the first phase, suitable noise detectors are used for identifying image pixels contaminated by noise. Then, in the second phase, based upon the information on the location of noise-free pixels, images are deblurred and denoised simultaneously. For efficiency reasons, in the second phase a superlinearly convergent algorithm based upon Fenchel-duality and inexact semismooth Newton techniques is utilized for solving the associated variational problem. Numerical results prove the new method to be a significantly advance over several state-of-the-art techniques with respect to restoration capability and computational efficiency.

  20. Evolution of THz impulse imaging radar to 1550nm photoconductive switches

    NASA Astrophysics Data System (ADS)

    Brown, E. R.; Zhang, W.-D.; Feldman, A.; Harvey, T.; Mirin, R. P.; Sung, S.; Grundfest, W. S.; Taylor, Z. D.

    2016-05-01

    We present measurements of sub-bandgap photoconductivity and photoconductive switches using GaAs doped heavily with Er such that nanoparticles of ErAs are formed. In addition to strong resonant absorption centered around 1550 nm, the material provides strong sub-bandgap photoconductivity and >> μW average power levels when fabricated into an efficient (square spiral) THz antenna and driven by a 1550- nm ultrafast fiber laser. Photo-Hall measurements prove that the predominant photocarrier is the electron and the linearity of the 1550-nm photocurrent (with laser power) suggests that the photoconductivity is "extrinsic", not other possible mechanisms, such as two-photon absorption. These results have immediate relevance to the use of GaAs:Er switches as the transmitter in 1550-nm-driven THz imaging systems such as the "impulse imager" that we have successfully used for biomedical imaging applications.

  1. Random impulse noise removal from image sequences based on fuzzy logic

    NASA Astrophysics Data System (ADS)

    Mélange, Tom; Nachtegael, Mike; Kerre, Etienne E.

    2011-01-01

    In this paper a new filter for image sequences corrupted with random impulse noise is presented. In order to preserve the image details as much as possible, the noise is removed in different successive filtering steps. In each step, only the pixels that are detected as being noisy are filtered, while the noise-free pixels remain unchanged. The noise detection is based on fuzzy set theory and fuzzy rules, which are very useful for the processing of human knowledge and linguistic values. To exploit the temporal information in image sequences as much as possible, detected pixels are finally filtered in a motion compensated way. From the experimental results it can be seen that the proposed method outperforms other state-of-the-art filters both in terms of the peak-signal-to-noise ratio, the mean absolute error, and visually.

  2. Impulse noise removal using 1-D switching median filter with adaptive scanning order based on structural context of image

    NASA Astrophysics Data System (ADS)

    Koga, Takanori; Suetake, Noriaki

    2015-02-01

    This paper describes the detail-preserving impulse noise removal performance of a one-dimensional (1-D) switching median filter (SMF) applied along an adaptive space-filling curve. Usually, a SMF with a two-dimensional (2-D) filter window is widely used for impulse noise removal while still preserving detailed parts in an input image. However, the noise detector of the 2-D filter does not always distinguish between the original pixels and the noise-corrupted ones perfectly. In particular, pixels constituting thin lines in an input image tend to be incorrectly detected as noise-corrupted pixels, and such pixels are filtered regardless of the necessity of the filtering. To cope with this problem, we propose a new impulse noise removal method based on a 1-D SMF and a space-filling curve which is adaptively drawn using a minimum spanning tree reflecting structural context of an input image.

  3. Fuzzy set and directional image processing techniques for impulsive noise reduction employing DSP

    NASA Astrophysics Data System (ADS)

    Ponomaryov, Volodymyr; Rosales-Silva, Alberto; Gallegos-Funes, Francisco

    2009-02-01

    In literature, numerous algorithms in image denoising in case of a noise of different nature were implemented. One of the principal noises is impulsive one companioning any transmission process. This paper presents novel approach unificating two most powerful techniques used during last years: directional processing and fuzzy-set techniques. Novel method permits the detection of noisy pixels and local movements (edges and fine details) in a static image or in an image sequence. The proposed algorithm realizes the noise suppression preserving fine details and edges, as so as color chromaticity properties in the multichannel image. We present applications of proposed algorithm in color imaging and in multichannel remote sensing from several bands. Finally, hardware requirements are evaluated permitting real time implementation on DSP of Texas Instruments using a Reference Framework defined as RF5. It was implemented on DSP the multichannel algorithms in a multitask process that permits to improve the performance of several tasks, and at the same time enhancing the time processing and reducing computational charge in a dedicated hardware. Numerous experimental results in the processing the color images/sequences and satellite remote sensing data show the superiority of proposed approach as in objective criteria (PSNR, MAE, NCD), as in visual subjective way. The needed processing times and visual characteristics are exposed in the paper demonstrating accepted performance of the approach.

  4. Acoustic radiation force impulse and supersonic shear imaging versus transient elastography for liver fibrosis assessment.

    PubMed

    Sporea, Ioan; Bota, Simona; Jurchis, Ana; Sirli, Roxana; Grădinaru-Tascău, Oana; Popescu, Alina; Ratiu, Iulia; Szilaski, Milana

    2013-11-01

    Our study compared three elastographic methods--transient elastography (TE), acoustic radiation force impulse (ARFI) imaging and supersonic shear imaging (SSI)--with respect to the feasibility of their use in liver fibrosis evaluation. We also compared the performance of ARFI imaging and SSI, with TE as the reference method. The study included 332 patients, with or without hepatopathies, in which liver stiffness was evaluated using TE, ARFI and SSI. Reliable measurements were defined as a median value of 10 (TE, ARFI imaging) or 5 (SSI) liver stiffness measurements with a success rate ≥60% and an interquartile range interval <30%. A significantly higher percentage of reliable measurements were obtained using ARFI than by using TE and SSI: 92.1% versus 72.2% (p < 0.0001) and 92.1% versus 71.3% (p < 0.0001). Higher body mass index and older age were significantly associated with inability to obtain reliable measurements of liver stiffness using TE and SSI. In 55.4% of patients, reliable liver stiffness measurements were obtained using all three elastographic methods, and ARFI imaging and TE were similarly accurate in diagnosing significant fibrosis and cirrhosis, with TE as the reference method.

  5. Intracardiac Acoustic Radiation Force Impulse Imaging: A Novel Imaging Method for Intraprocedural Evaluation of Radiofrequency Ablation Lesions

    PubMed Central

    Eyerly, Stephanie A.; Bahnson, Tristram D.; Koontz, Jason I.; Bradway, David P.; Dumont, Douglas M.; Trahey, Gregg E.; Wolf, Patrick D.

    2012-01-01

    Background Arrhythmia recurrence after cardiac radiofrequency ablation (RFA) for atrial fibrillation (AF) has been linked to conduction through discontinuous lesion lines. Intraprocedural visualization and corrective ablation of lesion line discontinuities could decrease post-procedure AF recurrence. Intracardiac acoustic radiation force impulse (ARFI) imaging is a new imaging technique that visualizes RFA lesions by mapping the relative elasticity contrast between compliant-unablated and stiff-RFA treated myocardium. Objective To determine if intraprocedure ARFI images can identify RFA treated myocardium in vivo. Methods In eight canines, an electroanatomical mapping (EAM) guided intracardiac echo catheter (ICE) was used to acquire 2D ARFI images along right atrial ablation lines before and after RFA. ARFI images were acquired during diastole with the myocardium positioned at the ARFI focus (1.5 cm) and parallel to the ICE transducer for maximal and uniform energy delivery to the tissue. Three reviewers categorized each ARFI image as depicting no lesion, non-contiguous, or contiguous lesion. For comparison, three separate reviewers confirmed RFA lesion presence and contiguity based on functional conduction block at the imaging plane location on EAM activation maps. Results Ten percent of ARFI images were discarded due to motion artifacts. Reviewers of the ARFI images detected RFA-treated sites with high sensitivity (95.7%) and specificity (91.5%). Reviewer identification of contiguous lesion had 75.3% specificity and 47.1% sensitivity. Conclusions Intracardiac ARFI imaging was successful in identifying endocardial RFA treatment when specific imaging conditions were maintained. Further advances in ARFI imaging technology would facilitate a wider range of imaging opportunities for clinical lesion evaluation. PMID:22772134

  6. Impulse radar imaging for dispersive concrete using inverse adaptive filtering techniques

    SciTech Connect

    Arellano, J.; Hernandez, J.M.; Brase, J.

    1993-05-01

    This publication addresses applications of a delayed inverse model adaptive filter for modeled data obtained from short-pulse radar reflectometry. To determine the integrity of concrete, a digital adaptive filter was used, which allows compensation of dispersion and clutter generated by the concrete. A standard set of weights produced by an adaptive filter are used on modeled data to obtain the inverse-impulse response of the concrete. The data for this report include: Multiple target, nondispersive data; single-target, variable-size dispersive data; single-target, variable-depth dispersive data; and single-target, variable transmitted-pulse-width dispersive data. Results of this simulation indicate that data generated by the weights of the adaptive filter, coupled with a two-dimensional, synthetic-aperture focusing technique, successfully generate two-dimensional images of targets within the concrete from modeled data.

  7. Acoustic radiation force impulse imaging of vulnerable plaques: a finite element method parametric analysis

    PubMed Central

    Doherty, Joshua R.; Dumont, Douglas M.; Trahey, Gregg E.; Palmeri, Mark L.

    2012-01-01

    Plaque rupture is the most common cause of complications such as stroke and coronary heart failure. Recent histopathological evidence suggests that several plaque features, including a large lipid core and a thin fibrous cap, are associated with plaques most at risk for rupture. Acoustic Radiation Force Impulse (ARFI) imaging, a recently developed ultrasound-based elasticity imaging technique, shows promise for imaging these features noninvasively. Clinically, this could be used to distinguish vulnerable plaques, for which surgical intervention may be required, from those less prone to rupture. In this study, a parametric analysis using Finite-Element Method (FEM) models was performed to simulate ARFI imaging of five different carotid artery plaques across a wide range of material properties. It was demonstrated that ARFI could resolve the softer lipid pool from the surrounding, stiffer media and fibrous cap and was most dependent upon the stiffness of the lipid pool component. Stress concentrations due to an ARFI excitation were located in the media and fibrous cap components. In all cases, the maximum Von Mises stress was < 1.2 kPa. In comparing these results with others investigating plaque rupture, it is concluded that while the mechanisms may be different, the Von Mises stresses imposed by ARFI are orders of magnitude lower than the stresses associated with blood pressure. PMID:23122224

  8. Intracardiac Acoustic Radiation Force Impulse (ARFI) and Shear Wave Imaging in Pigs with Focal Infarctions

    PubMed Central

    Hollender, Peter; Bradway, David; Wolf, Patrick; Goswami, Robi; Trahey, Gregg

    2013-01-01

    Four pigs, three with focal infarctions in the apical intraventricular septum (IVS) and/or left ventricular free wall (LVFW), were imaged with an intracardiac echocardiography (ICE) transducer. Custom beam sequences were used to excite the myocardium with focused acoustic radiation force (ARF) impulses and image the subsequent tissue response. Tissue displacement in response to the ARF excitation was calculated with a phase-based estimator, and transverse wave magnitude and velocity were each estimated at every depth. The excitation sequence was repeated rapidly, either in the same location to generate 40 Hz M-Modes at a single steering angle, or with a modulated steering angle to synthesize 2-D displacement magnitude and shear wave velocity images at 17 points in the cardiac cycle. Both types of images were acquired from various views in the right and left ventricles, in and out of infarcted regions. In all animals, ARFI and SWEI estimates indicated diastolic relaxation and systolic contraction in non-infarcted tissues. The M-Mode sequences showed high beat-to-beat spatio-temporal repeatability of the measurements for each imaging plane. In views of noninfarcted tissue in the diseased animals, no significant elastic remodeling was indicated when compared to the control. Where available, views of infarcted tissue were compared to similar views from the control animal. In views of the LVFW, the infarcted tissue presented as stiff and non-contractile compared to the control. In a view of the IVS, no significant difference was seen between infarcted and healthy tissue, while in another view, a heterogeneous infarction was seen presenting itself as non-contractile in systole. PMID:25004538

  9. The electric organ discharge of pulse gymnotiforms: the transformation of a simple impulse into a complex spatio-temporal electromotor pattern

    PubMed

    Caputi

    1999-05-01

    An understanding of how the nervous system processes an impulse-like input to yield a stereotyped, species-specific electromotor output is relevant for electric fish physiology, but also for understanding the general mechanisms of coordination of effector patterns. In pulse gymnotids, the electromotor system is repetitively activated by impulse-like signals generated by a pacemaker nucleus in the medulla. This nucleus activates a set of relay cells whose axons descend along the spinal cord and project to electromotor neurones which, in turn, project to electrocytes. Relay neurones, electromotor neurones and electrocytes may be considered as layers of a network arranged with a lattice hierarchy. This network is able to coordinate a spatio-temporal pattern of postsynaptic and action currents generated by the electrocyte membranes. Electrocytes may be innervated at their rostral face, at their caudal face or at both faces, depending on the site of the organ and the species. Thus, the species-specific electric organ discharge patterns depend on the electric organ innervation pattern and on the coordinated activation of the electrocyte faces. The activity of equally oriented faces is synchronised by a synergistic combination of delay lines. The activation of oppositely oriented faces is coordinated in a precise sequence resulting from the orderly recruitment of subsets of electromotor neurones according to the 'size principle' and to their position along the spinal cord. The body of the animal filters the electric organ output electrically, and the whole fish is transformed into a distributed electric source.

  10. New Developments in Human Neurocognition: Clinical, Genetic and Brain Imaging Correlates of Impulsivity and Compulsivity

    PubMed Central

    Fineberg, Naomi A.; Chamberlain, Samuel R.; Goudriaan, Anna E.; Stein, Dan J.; Vanderschuren, Louk J.M.J.; Gillan, Claire M.; Shekar, Sameer; Gorwood, Philip A.P.M.; Voon, Valerie; Morein-Zamir, Sharon; Denys, Damiaan; Sahakian, Barbara J.; Moeller, F. Gerard; Robbins, Trevor W.; Potenza, Marc N.

    2014-01-01

    Impulsivity and compulsivity represent useful conceptualizations that involve dissociable cognitive functions, mediated by neuroanatomically and neurochemically distinct components of cortico-subcortical circuitry. The constructs were historically viewed as diametrically opposed, with impulsivity being associated with risk-seeking and compulsivity with harm-avoidance. However, they are increasingly recognized to be linked by shared neuropsychological mechanisms involving dysfunctional inhibition of thoughts and behaviors. In this paper, we selectively review new developments in the investigation of the neurocognition of impulsivity and compulsivity in humans, in order to advance our understanding of the pathophysiology of impulsive, compulsive and addictive disorders and indicate new directions for research. PMID:24512640

  11. High power impulse magnetron sputtering and related discharges: scalable plasma sources for plasma-based ion implantation and deposition

    SciTech Connect

    Anders, Andre

    2009-09-01

    High power impulse magnetron sputtering (HIPIMS) and related self-sputtering techniques are reviewed from a viewpoint of plasma-based ion implantation and deposition (PBII&D). HIPIMS combines the classical, scalable sputtering technology with pulsed power, which is an elegant way of ionizing the sputtered atoms. Related approaches, such as sustained self-sputtering, are also considered. The resulting intense flux of ions to the substrate consists of a mixture of metal and gas ions when using a process gas, or of metal ions only when using `gasless? or pure self-sputtering. In many respects, processing with HIPIMS plasmas is similar to processing with filtered cathodic arc plasmas, though the former is easier to scale to large areas. Both ion implantation and etching (high bias voltage, without deposition) and thin film deposition (low bias, or bias of low duty cycle) have been demonstrated.

  12. Electric organ discharges and electric images during electrolocation

    NASA Technical Reports Server (NTRS)

    Assad, C.; Rasnow, B.; Stoddard, P. K.

    1999-01-01

    Weakly electric fish use active electrolocation - the generation and detection of electric currents - to explore their surroundings. Although electrosensory systems include some of the most extensively understood circuits in the vertebrate central nervous system, relatively little is known quantitatively about how fish electrolocate objects. We believe a prerequisite to understanding electrolocation and its underlying neural substrates is to quantify and visualize the peripheral electrosensory information measured by the electroreceptors. We have therefore focused on reconstructing both the electric organ discharges (EODs) and the electric images resulting from nearby objects and the fish's exploratory behaviors. Here, we review results from a combination of techniques, including field measurements, numerical and semi-analytical simulations, and video imaging of behaviors. EOD maps are presented and interpreted for six gymnotiform species. They reveal diverse electric field patterns that have significant implications for both the electrosensory and electromotor systems. Our simulations generated predictions of the electric images from nearby objects as well as sequences of electric images during exploratory behaviors. These methods are leading to the identification of image features and computational algorithms that could reliably encode electrosensory information and may help guide electrophysiological experiments exploring the neural basis of electrolocation.

  13. Observation of a periodic runaway in the reactive Ar/O{sub 2} high power impulse magnetron sputtering discharge

    SciTech Connect

    Shayestehaminzadeh, Seyedmohammad E-mail: shayesteh@mch.rwth-aachen.de; Arnalds, Unnar B.; Magnusson, Rögnvaldur L.; Olafsson, Sveinn

    2015-11-15

    This paper reports the observation of a periodic runaway of plasma to a higher density for the reactive discharge of the target material (Ti) with moderate sputter yield. Variable emission of secondary electrons, for the alternating transition of the target from metal mode to oxide mode, is understood to be the main reason for the runaway occurring periodically. Increasing the pulsing frequency can bring the target back to a metal (or suboxide) mode, and eliminate the periodic transition of the target. Therefore, a pulsing frequency interval is defined for the reactive Ar/O{sub 2} discharge in order to sustain the plasma in a runaway-free mode without exceeding the maximum power that the magnetron can tolerate.

  14. Testicular microlithiasis and preliminary experience of acoustic radiation force impulse imaging

    PubMed Central

    Osther, Palle Jørn Sloth; Rafaelsen, Søren Rafael

    2016-01-01

    Background Elastography of the testis can be used as a part of multiparametric examination of the scrotum. Purpose To determine the testicular stiffness using acoustic radiation force impulse imaging (ARFI) technique in men with testicular microlithiasis (TML). Material and Methods In 2013, 12 patients with diagnosed testicular microlithiasis in 2008 (mean age, 51 years; age range, 25–76 years) underwent a 5-year follow-up B-mode ultrasonography with three ARFI elastography measurements of each testis. We used a Siemens Acuson S3000 machine. Results No malignancy was found at the 5-year follow-up B-mode and elastography in 2013. However, we found an increase in TML; in the previous ultrasonography in 2008, eight men had bilateral TML, whereas in 2013, 10 men were diagnosed with bilateral TML. The mean elasticity of testicles with TML was 0.82 m/s (interquartile range [IQR], 0.72–0.88 m/s; range, 65–1.08 m/s). Conclusion Elastography velocity of testis with TML seems to be in the same velocity range as in men with normal testis tissue. PMID:27504193

  15. Recent Insights into the Neurobiology of Impulsivity

    PubMed Central

    Mitchell, Marci R.; Potenza, Marc N.

    2014-01-01

    Impulsivity is associated with various psychopathologies, and elevated impulsivity is typically disadvantageous. This manuscript reviews recent investigations into the neurobiology of impulsivity using human imaging techniques and animal models. Both human imaging and preclinical pharmacological manipulations have yielded important insights into the neurobiological underpinnings of impulsivity. A more thorough understanding of the complex neurobiology underlying aspects of impulsivity may provide insight into new treatment options that target elevated impulsivity and psychopathologies such as addictions. PMID:25431750

  16. X-ray Diffraction and Multi-Frame Phase Contrast Imaging Diagnostics for IMPULSE at the Advanced Photon Source

    SciTech Connect

    Iverson, Adam; Carlson, Carl; Young, Jason; Curtis, Alden; Jensen, Brian; Ramos, Kyle; Yeager, John; Montgomery, David; Fezza, Kamel

    2013-07-08

    The diagnostic needs of any dynamic loading platform present unique technical challenges that must be addressed in order to accurately measure in situ material properties in an extreme environment. The IMPULSE platform (IMPact system for Ultrafast Synchrotron Experiments) at the Advanced Photon Source (APS) is no exception and, in fact, may be more challenging, as the imaging diagnostics must be synchronized to both the experiment and the 60 ps wide x-ray bunches produced at APS. The technical challenges of time-resolved x-ray diffraction imaging and high-resolution multi-frame phase contrast imaging (PCI) are described in this paper. Example data from recent IMPULSE experiments are shown to illustrate the advances and evolution of these diagnostics with a focus on comparing the performance of two intensified CCD cameras and their suitability for multi-frame PCI. The continued development of these diagnostics is fundamentally important to IMPULSE and many other loading platforms and will benefit future facilities such as the Dynamic Compression Sector at APS and MaRIE at Los Alamos National Laboratory.

  17. Comparison of ultrasound B-mode, strain imaging, acoustic radiation force impulse displacement and shear wave velocity imaging using real time clinical breast images

    NASA Astrophysics Data System (ADS)

    Manickam, Kavitha; Machireddy, Ramasubba Reddy; Raghavan, Bagyam

    2016-04-01

    It has been observed that many pathological process increase the elastic modulus of soft tissue compared to normal. In order to image tissue stiffness using ultrasound, a mechanical compression is applied to tissues of interest and local tissue deformation is measured. Based on the mechanical excitation, ultrasound stiffness imaging methods are classified as compression or strain imaging which is based on external compression and Acoustic Radiation Force Impulse (ARFI) imaging which is based on force generated by focused ultrasound. When ultrasound is focused on tissue, shear wave is generated in lateral direction and shear wave velocity is proportional to stiffness of tissues. The work presented in this paper investigates strain elastography and ARFI imaging in clinical cancer diagnostics using real time patient data. Ultrasound B-mode imaging, strain imaging, ARFI displacement and ARFI shear wave velocity imaging were conducted on 50 patients (31 Benign and 23 malignant categories) using Siemens S2000 machine. True modulus contrast values were calculated from the measured shear wave velocities. For ultrasound B-mode, ARFI displacement imaging and strain imaging, observed image contrast and Contrast to Noise Ratio were calculated for benign and malignant cancers. Observed contrast values were compared based on the true modulus contrast values calculated from shear wave velocity imaging. In addition to that, student unpaired t-test was conducted for all the four techniques and box plots are presented. Results show that, strain imaging is better for malignant cancers whereas ARFI imaging is superior than strain imaging and B-mode for benign lesions representations.

  18. Acoustic radiation force impulse imaging for assessing liver fibrosis in alcoholic liver disease

    PubMed Central

    Kiani, Anita; Brun, Vanessa; Lainé, Fabrice; Turlin, Bruno; Morcet, Jeff; Michalak, Sophie; Le Gruyer, Antonia; Legros, Ludivine; Bardou-Jacquet, Edouard; Gandon, Yves; Moirand, Romain

    2016-01-01

    AIM: To evaluate the performance of elastography by ultrasound with acoustic radiation force impulse (ARFI) in determining fibrosis stage in patients with alcoholic liver disease (ALD) undergoing alcoholic detoxification in relation to biopsy. METHODS: Eighty-three patients with ALD undergoing detoxification were prospectively enrolled. Each patient underwent ARFI imaging and a liver biopsy on the same day. Fibrosis was staged according to the METAVIR scoring system. The median of 10 valid ARFI measurements was calculated for each patient. RESULTS: Sixty-nine males and thirteen females (one patient excluded due to insufficient biopsy size) were assessed with a mean alcohol consumption of 132.4 ± 128.8 standard drinks per week and mean cumulative year duration of 17.6 ± 9.5 years. Sensitivity and specificity were respectively 82.4% (0.70-0.95) and 83.3% (0.73-0.94) (AUROC = 0.87) for F ≥ 2 with a cut-off value of 1.63m/s; 82.4% (0.64-1.00) and 78.5% (0.69-0.89) (AUROC = 0.86) for F ≥ 3 with a cut-off value of 1.84m/s; and 92.3% (0.78-1.00] and 81.6% (0.72-0.90) (AUROC = 0.89) for F = 4 with a cut-off value of 1.94 m/s. CONCLUSION: ARFI is an accurate, non-invasive and easy method for assessing liver fibrosis in patients with ALD undergoing alcoholic detoxification. PMID:27239119

  19. Management of nipple discharge and the associated imaging findings.

    PubMed

    Patel, Bhavika K; Falcon, Shannon; Drukteinis, Jennifer

    2015-04-01

    Nipple discharge is commonly encountered by health care providers, accounting for 2%-5% of medical visits by women. Because nipple discharge is the presenting symptom in 5% to 12% of breast cancers, it causes considerable anxiety for both patient and providers. Furthermore, the work-up and management of nipple discharge can be confusing. Fortunately, the cause of nipple discharge is usually benign, so the primary goal of evaluation and management is separation of patients with pathologic causes of discharge from those with benign or physiologic causes. The evaluation of nipple discharge requires a thorough history, careful physical examination, and an informed approach that selects the most suitable diagnostic modality. Primary care providers, working with their radiologists and surgeons, are well positioned to design appropriate diagnostic and management protocols to assess and treat nipple discharge. A thoughtful and prudent approach to nipple discharge should alleviate patient anxiety by efficiently and effectively defining the underlying etiology.

  20. Primary biliary cirrhosis degree assessment by acoustic radiation force impulse imaging and hepatic fibrosis indicators

    PubMed Central

    Zhang, Hai-Chun; Hu, Rong-Fei; Zhu, Ting; Tong, Ling; Zhang, Qiu-Qin

    2016-01-01

    AIM: To evaluate the assessment of primary biliary cirrhosis degree by acoustic radiation force impulse imaging (ARFI) and hepatic fibrosis indicators. METHODS: One hundred and twenty patients who developed liver cirrhosis secondary to primary biliary cirrhosis were selected as the observation group, with the degree of patient liver cirrhosis graded by Child-Pugh (CP) score. Sixty healthy individuals were selected as the control group. The four indicators of hepatic fibrosis were detected in all research objects, including hyaluronic acid (HA), laminin (LN), type III collagen (PC III), and type IV collagen (IV-C). The liver parenchyma hardness value (LS) was then measured by ARFI technique. LS and the four indicators of liver fibrosis (HA, LN, PC III, and IV-C) were observed in different grade CP scores. The diagnostic value of LS and the four indicators of liver fibrosis in determining liver cirrhosis degree with PBC, whether used alone or in combination, were analyzed by receiver operating characteristic (ROC) curve. RESULTS: LS and the four indicators of liver fibrosis within the three classes (A, B, and C) of CP scores in the observation group were higher than in the control group, with C class > B class > A class; the differences were statistically significant (P < 0.01). Although AUC values of LS within the three classes of CP scores were higher than in the four indicators of liver fibrosis, sensitivity and specificity were unstable. The ROC curves of LS combined with the four indicators of liver fibrosis revealed that: AUC and sensitivity in all indicators combined in the A class of CP score were higher than in LS alone, albeit with slightly decreased specificity; AUC and specificity in all indicators combined in the B class of CP score were higher than in LS alone, with unchanged sensitivity; AUC values (0.967), sensitivity (97.4%), and specificity (90%) of all indicators combined in the C class of CP score were higher than in LS alone (0.936, 92.1%, 83

  1. Instantaneous Impulses.

    ERIC Educational Resources Information Center

    Erlichson, Herman

    2000-01-01

    Describes an experiment that extends Newton's instantaneous-impulse method of orbital analysis to a graphical method of orbit determination. Discusses the experiment's usefulness for teaching both horizontal projectile motion and instantaneous impulse. (WRM)

  2. Television image of a large upward electrical discharge above a thunderstorm system

    NASA Technical Reports Server (NTRS)

    Franz, R. C.; Nemzek, R. J.; Winckler, J. R.

    1990-01-01

    A low light-level TV camera is used to obtain an unusual image of luminous electrical discharge over a thunderstorm 250 km from the observation site. The image is presented and the discharge in the image is described. It is suggested that the image is probably due to two localized electric charge concentrations at the cloud tops. The hazard of these discharges for aircraft and rocket launches is examined. Consideration is given to the possibility that these discharges may account for unexplained photometric observations of distant lightning events that show a low rise rate of the luminous pulse and no electromagnetic sferic pulse like that in cloud-to-earth lightning strokes. The photometric events of this type that occurred on September 22-23, 1989 during hurricane Hugo are noted.

  3. An improved peer group method to filter impulsive noise for color images

    NASA Astrophysics Data System (ADS)

    Zhu, Yuhong; Jiang, Huageng; Feng, Jinting

    2015-07-01

    This paper presents an improved filter method based on the lately proposed method of IFPGF[1] which is peer group-based. The IFPGF method improves the trade-off between computational efficiency and filtering quality of previous peer group-based methods and gains a good filtering quality at relatively low density of noisy pixels. But when the noisy density goes high(≥20%), the IFPGF method cannot work well. So in this paper, we propose an improved method to fix the drawbacks on filtering the salt-and-pepper impulsive noise. Experimental results suggest that the proposed method is able to outperform the classical vector filters and the recent proposed p eer group-based filters, including IFPGF.

  4. Employing partially coherent, compact gas-discharge sources for coherent diffractive imaging with extreme ultraviolet light

    NASA Astrophysics Data System (ADS)

    Bußmann, J.; Odstrčil, M.; Bresenitz, R.; Rudolf, D.; Miao, Jianwei; Brocklesby, W. S.; Grützmacher, D.; Juschkin, L.

    2015-09-01

    Coherent diffractive imaging (CDI) and related techniques enable a new type of diffraction-limited high-resolution extreme ultraviolet (EUV) microscopy. Here, we demonstrate CDI reconstruction of a complex valued object under illumination by a compact gas-discharge EUV light source emitting at 17.3 nm (O VI spectral line). The image reconstruction method accounts for the partial spatial coherence of the radiation and allows imaging even with residual background light. These results are a first step towards laboratory-scale CDI with a gas-discharge light source for applications including mask inspection for EUV lithography, metrology and astronomy.

  5. Optically measured explosive impulse

    NASA Astrophysics Data System (ADS)

    Biss, Matthew M.; McNesby, Kevin L.

    2014-06-01

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

  6. A theoretical study of inertial cavitation from acoustic radiation force impulse (ARFI) imaging and implications for the mechanical index

    PubMed Central

    Church, Charles C.; Labuda, Cecille; Nightingale, Kathryn

    2014-01-01

    The mechanical index (MI) attempts to quantify the likelihood that exposure to diagnostic ultrasound will produce an adverse biological effect by a nonthermal mechanism. The current formulation of the MI implicitly assumes that the acoustic field is generated using the short pulse durations appropriate to B-mode imaging. However, acoustic radiation force impulse (ARFI) imaging employs high-intensity pulses up to several hundred acoustic periods long. The effect of increased pulse durations on the thresholds for inertial cavitation was studied computationally in water, urine, blood, cardiac and skeletal muscle, brain, kidney, liver and skin. The results show that while the effect of pulse duration on cavitation thresholds in the three liquids can be considerable, reducing them by, e.g., 6% – 24% at 1 MHz, the effect in tissue is minor. More importantly, the frequency dependence of the MI appears to be unnecessarily conservative, i.e., that the magnitude of the exponent on frequency could be increased to 0.75. Comparison of these theoretical results with experimental measurements suggests that some tissues do not contain the pre-existing, optimally sized bubbles assumed for the MI. This means that in these tissues the MI is not necessarily a strong predictor of the probability for an adverse biological effect. PMID:25592457

  7. Evaluating the intensity of the acoustic radiation force impulse (ARFI) in intravascular ultrasound (IVUS) imaging: Preliminary in vitro results.

    PubMed

    Shih, Cho-Chiang; Lai, Ting-Yu; Huang, Chih-Chung

    2016-08-01

    The ability to measure the elastic properties of plaques and vessels is significant in clinical diagnosis, particularly for detecting a vulnerable plaque. A novel concept of combining intravascular ultrasound (IVUS) imaging and acoustic radiation force impulse (ARFI) imaging has recently been proposed. This method has potential in elastography for distinguishing between the stiffness of plaques and arterial vessel walls. However, the intensity of the acoustic radiation force requires calibration as a standard for the further development of an ARFI-IVUS imaging device that could be used in clinical applications. In this study, a dual-frequency transducer with 11MHz and 48MHz was used to measure the association between the biological tissue displacement and the applied acoustic radiation force. The output intensity of the acoustic radiation force generated by the pushing element ranged from 1.8 to 57.9mW/cm(2), as measured using a calibrated hydrophone. The results reveal that all of the acoustic intensities produced by the transducer in the experiments were within the limits specified by FDA regulations and could still displace the biological tissues. Furthermore, blood clots with different hematocrits, which have elastic properties similar to the lipid pool of plaques, with stiffness ranging from 0.5 to 1.9kPa could be displaced from 1 to 4μm, whereas the porcine arteries with stiffness ranging from 120 to 291kPa were displaced from 0.4 to 1.3μm when an acoustic intensity of 57.9mW/cm(2) was used. The in vitro ARFI images of the artery with a blood clot and artificial arteriosclerosis showed a clear distinction of the stiffness distributions of the vessel wall. All the results reveal that ARFI-IVUS imaging has the potential to distinguish the elastic properties of plaques and vessels. Moreover, the acoustic intensity used in ARFI imaging has been experimentally quantified. Although the size of this two-element transducer is unsuitable for IVUS imaging, the

  8. Acoustic Radiation Force Impulse Imaging for Noninvasive Evaluation of Renal Parenchyma Elasticity: Preliminary Findings

    PubMed Central

    Xu, Hui-Xiong; Peng, Ai; Zhang, Yi-Feng; Liu, Lin-Na

    2013-01-01

    Objective To evaluate the diagnostic value of acoustic radiation force impulse (ARFI) to test the elasticity of renal parenchyma by measuring the shear wave velocity (SWV) which might be used to detect chronic kidney disease (CKD). Methods 327 healthy volunteers and 64 CKD patients were enrolled in the study. The potential influencing factors and measurement reproducibility were evaluated in the healthy volunteers. Correlations between SWV and laboratory tests were analyzed in CKD patients.?Receiver-operating characteristic curve (ROC) analyses were performed to assess the diagnostic performance of ARFI. Results The SWV of healthy volunteers correlated significantly to age (r = −0.22, P<0.001, n = 327) and differed significantly between men and women (2.06±0.48 m/s vs. 2.2±0.52 m/s, P = 0.018, n = 327). However, it did not correlate significantly to height, weight, body mass index, waistline, kidney dimension and the depth for SWV measurement (n = 30). Inter- and intraobserver agreement expressed as intraclass coefficient correlation were 0.64 (95% CI: 0.13 to 0.82, P = 0.011) and 0.6 (95% CI: 0.31 to 0.81, P = 0.001) (n = 40). The mean SWV in healthy volunteers was 2.15±0.51 m/s, while was 1.81±0.43 m/s, 1.79±0.29 m/s, 1.81±0.44 m/s, 1.64±0.55 m/s, and 1.36±0.17 m/s for stage 1, 2, 3, 4 and 5 in CKD patients respectively. The SWV was significantly higher for healthy volunteers compared with each stage in CKD patients. ARFI could not predict the different stages of CKD except stage 5. In CKD patients, SWV correlated to e-GFR (r = 0.3, P = 0.018), to urea nitrogen (r =  −0.3, P = 0.016), and to creatinine (r =  −0.41, P = 0.001). ROC analyses indicated that the area under the ROC curve was 0.752 (95% CI: 0.704 to 0.797) (P<0.001). The cut-off value for predicting CKD was 1.88 m/s (sensitivity 71.87% and specificity 69.69%). Conclusion ARFI may be a potentially useful tool in detecting CKD. PMID

  9. Ground truth for SIR-B images obtained by SIR system 8 impulse radar

    NASA Technical Reports Server (NTRS)

    Ulriksen, P.; Ottersten, H.; Borg, C. G.; Axelsson, S.; Ekengren, B.

    1984-01-01

    Verification of suspected penetration by means of three dimensional information on the features in the SIR-B images will be investigated. The Great Alvar is a well documented area, especially in geology and ecology, and should provide a good opportunity to evaluate the data.

  10. Effect of liposomal local therapy on salivary glands in acoustic radiation force impulse imaging in Sjögren's syndrome.

    PubMed

    Hofauer, Benedikt; Mansour, Naglaa; Heiser, Clemens; Straßen, Ulrich; Bas, Murat; Knopf, Andreas

    2016-10-01

    The purpose of this study was to evaluate the utility of acoustic radiation force impulse (ARFI) imaging as a monitoring tool for the effect of a liposomal local therapy in patients with dry mouth symptoms due to primary Sjögren's syndrome (pSS). Fifty patients with pSS, diagnosed according to the American-European Consensus Group (AECG) criteria, were included. Clinical data were collected, and sonographic examination including ARFI imaging of the parotid and submandibular glands was performed. Subjective symptoms were evaluated via visual analogue scales (VAS), and the unstimulated whole salivary flow was measured. After a two-month period of liposomal local therapy, sonographic examination was repeated and both subjective and objective symptoms were re-evaluated. Before local treatment, the mean ARFI value of parotid glands was 2.96 m/s (SD 0.97). Mean ARFI value of the submandibular glands was 2.09 m/s (SD 0.71). After the two-month treatment period, a significant decline of ARFI values in the parotid glands to a value of 2.34 m/s (SD 0.70, p < 0.001) could be observed. The submandibular glands did not show any significant change. Further, a significant reduction of the subjective sensation of dry mouth symptoms could be observed (p = 0.0001). With the application of ARFI imaging, a decline in parotid gland stiffness could be observed in patients with primary Sjögren's Syndrome accompanied by a significant improvement of the subjective sensation of dry mouth symptoms. The seromucous submandibular glands did not show any changes compared to the serous parotid glands.

  11. Effect of liposomal local therapy on salivary glands in acoustic radiation force impulse imaging in Sjögren's syndrome.

    PubMed

    Hofauer, Benedikt; Mansour, Naglaa; Heiser, Clemens; Straßen, Ulrich; Bas, Murat; Knopf, Andreas

    2016-10-01

    The purpose of this study was to evaluate the utility of acoustic radiation force impulse (ARFI) imaging as a monitoring tool for the effect of a liposomal local therapy in patients with dry mouth symptoms due to primary Sjögren's syndrome (pSS). Fifty patients with pSS, diagnosed according to the American-European Consensus Group (AECG) criteria, were included. Clinical data were collected, and sonographic examination including ARFI imaging of the parotid and submandibular glands was performed. Subjective symptoms were evaluated via visual analogue scales (VAS), and the unstimulated whole salivary flow was measured. After a two-month period of liposomal local therapy, sonographic examination was repeated and both subjective and objective symptoms were re-evaluated. Before local treatment, the mean ARFI value of parotid glands was 2.96 m/s (SD 0.97). Mean ARFI value of the submandibular glands was 2.09 m/s (SD 0.71). After the two-month treatment period, a significant decline of ARFI values in the parotid glands to a value of 2.34 m/s (SD 0.70, p < 0.001) could be observed. The submandibular glands did not show any significant change. Further, a significant reduction of the subjective sensation of dry mouth symptoms could be observed (p = 0.0001). With the application of ARFI imaging, a decline in parotid gland stiffness could be observed in patients with primary Sjögren's Syndrome accompanied by a significant improvement of the subjective sensation of dry mouth symptoms. The seromucous submandibular glands did not show any changes compared to the serous parotid glands. PMID:27572326

  12. Assessment of liver fibrosis with 2-D shear wave elastography in comparison to transient elastography and acoustic radiation force impulse imaging in patients with chronic liver disease.

    PubMed

    Gerber, Ludmila; Kasper, Daniela; Fitting, Daniel; Knop, Viola; Vermehren, Annika; Sprinzl, Kathrin; Hansmann, Martin L; Herrmann, Eva; Bojunga, Joerg; Albert, Joerg; Sarrazin, Christoph; Zeuzem, Stefan; Friedrich-Rust, Mireen

    2015-09-01

    Two-dimensional shear wave elastography (2-D SWE) is an ultrasound-based elastography method integrated into a conventional ultrasound machine. It can evaluate larger regions of interest and, therefore, might be better at determining the overall fibrosis distribution. The aim of this prospective study was to compare 2-D SWE with the two best evaluated liver elastography methods, transient elastography and acoustic radiation force impulse (point SWE using acoustic radiation force impulse) imaging, in the same population group. The study included 132 patients with chronic hepatopathies, in which liver stiffness was evaluated using transient elastography, acoustic radiation force impulse imaging and 2-D SWE. The reference methods were liver biopsy for the assessment of liver fibrosis (n = 101) and magnetic resonance imaging/computed tomography for the diagnosis of liver cirrhosis (n = 31). No significant difference in diagnostic accuracy, assessed as the area under the receiver operating characteristic curve (AUROC), was found between the three elastography methods (2-D SWE, transient elastography, acoustic radiation force impulse imaging) for the diagnosis of significant and advanced fibrosis and liver cirrhosis in the "per protocol" (AUROCs for fibrosis stages ≥2: 0.90, 0.95 and 0.91; for fibrosis stage [F] ≥3: 0.93, 0.95 and 0.94; for F = 4: 0.92, 0.96 and 0.92) and "intention to diagnose" cohort (AUROCs for F ≥2: 0.87, 0.92 and 0.91; for F ≥3: 0.91, 0.93 and 0.94; for F = 4: 0.88, 0.90 and 0.89). Therefore, 2-D SWE, ARFI imaging and transient elastography seem to be comparably good methods for non-invasive assessment of liver fibrosis.

  13. Fast imaging of intermittent electrospraying of water with positive corona discharge

    NASA Astrophysics Data System (ADS)

    Pongrác, B.; Kim, H. H.; Janda, M.; Martišovitš, V.; Machala, Z.

    2014-08-01

    The effect of the electrospraying of water in combination with a positive direct current (dc) streamer corona discharge generated in air was investigated in this paper. We employed high-speed camera visualizations and oscilloscopic discharge current measurements in combination with an intensified charge-coupled device camera for fast time-resolved imaging. The repetitive process of Taylor cone formation and droplet formation from the mass fragments of water during the electrospray was visualized. Depending on the applied voltage, the following intermittent modes of electrospraying typical for water were observed: dripping mode, spindle mode, and oscillating-spindle mode. The observed electrospraying modes were repetitive with a frequency of a few hundreds of Hz, as measured from the fast image sequences. This frequency agreed well with the frequency of the measured streamer current pulses. The presence of filamentary streamer discharges at relatively low voltages probably prevented the establishment of a continuous electrospray in the cone-jet mode. After each streamer, a positive glow corona discharge was established on the water filament tip, and it propagated from the stressed electrode along with the water filament elongation. The results show a reciprocal character of intermittent electrospraying of water, and the presence of corona discharge, where both the electrospray and the discharge affect each other. The generation of a corona discharge from the water cone depended on the repetitive process of the cone formation. Also, the propagation and curvature of the water filament were influenced by the discharge and its resultant space charge. Furthermore, these phenomena were partially influenced by the water conductivity.

  14. Acoustic Radiation Force Impulse Imaging: A New Tool for the Diagnosis of Papillary Thyroid Microcarcinoma

    PubMed Central

    Zhang, Yi-Feng; Xu, Jun-Mei; Zhang, Jing; Liu, Lin-Na; Xu, Xiao-Hong

    2014-01-01

    Purpose. To evaluate the diagnostic performance of ARFI imaging in differentiating between benign and malignant thyroid nodules <1 cm. Materials and Methods. 173 pathologically proven thyroid nodules (77 benign, 96 malignant) in 157 patients were included in this study. Receiver-operating characteristic curve (ROC) analyses were performed to assess the diagnostic performance of conventional ultrasound (US) and ARFI imaging in papillary thyroid microcarcinoma (PTMC). The independent risk factors for predicting PTMC were evaluated. Results. The mean SWV value of benign and malignant thyroid nodules were 2.57 ± 0.79 m/s (range: 0.90–4.92 m/s) and 3.88 ± 2.24 m/s (range: 1.49–9.00 m/s) (P = 0.000). Az for VTI elastography score was higher than that for hypoechoic, absence of halo sign, and type III vascularity (P < 0.05). The optimal cut-offs for VTI elastography score and SWV were score 4 and 3.10 m/s. Gender, hypoechoic, taller than wide, VTI elastography score ≥ 4, and SWV > 3.10 m/s had been found to be independent risk factors for predicting PTMC. Conclusion. ARFI elastography can provide elasticity information of PTMC quantitatively (VTQ) and directly reflects the overall elastic properties (VTI). Gender, hypoechogenicity, taller than wide, VTI elastography score ≥ 4, and SWV > 3.10 m/s are independent risk factors for predicting PTMC. ARFI elastography seems to be a new tool for the diagnosis of PTMC. PMID:25045673

  15. A time-resolved imaging and electrical study on a high current atmospheric pressure spark discharge

    NASA Astrophysics Data System (ADS)

    Palomares, J. M.; Kohut, A.; Galbács, G.; Engeln, R.; Geretovszky, Zs.

    2015-12-01

    We present a time-resolved imaging and electrical study of an atmospheric pressure spark discharge. The conditions of the present study are those used for nanoparticle generation in spark discharge generator setups. The oscillatory bipolar spark discharge was generated between two identical Cu electrodes in different configurations (cylindrical flat-end or tipped-end geometries, electrode gap from 0.5 to 4 mm), in a controlled co-axial N2 flow, and was supplied by a high voltage capacitor. Imaging data with nanosecond time resolution were collected using an intensified CCD camera. This data were used to study the time evolution of plasma morphology, total light emission intensity, and the rate of plasma expansion. High voltage and high current probes were employed to collect electrical data about the discharge. The electrical data recorded allowed, among others, the calculation of the equivalent resistance and inductance of the circuit, estimations for the energy dissipated in the spark gap. By combining imaging and electrical data, observations could be made about the correlation of the evolution of total emitted light and the dissipated power. It was also observed that the distribution of light emission of the plasma in the spark gap is uneven, as it exhibits a "hot spot" with an oscillating position in the axial direction, in correlation with the high voltage waveform. The initial expansion rate of the cylindrical plasma front was found to be supersonic; thus, the discharge releases a strong shockwave. Finally, the results on equivalent resistance and channel expansion are comparable to those of unipolar arcs. This shows the spark discharge has a similar behavior to the arc regime during the conductive phase and until the current oscillations stop.

  16. B-Mode and Acoustic Radiation Force Impulse (ARFI) Imaging of Prostate Zonal Anatomy: Comparison with 3T T2-Weighted MR Imaging

    PubMed Central

    Palmeri, Mark L.; Miller, Zachary A.; Glass, Tyler J.; Garcia-Reyes, Kirema; Gupta, Rajan T.; Rosenzweig, Stephen J.; Kauffman, Christopher; Polascik, Thomas J.; Buck, Andrew; Kulbacki, Evan; Madden, John; Lipman, Samantha L.; Rouze, Ned C.; Nightingale, Kathryn R.

    2015-01-01

    Prostate cancer (PCa) is the most common non-cutaneous malignancy among men in the United States and the second leading cause of cancer-related death. Multi-parametric magnetic resonance imaging (mpMRI) has gained recent popularity to characterize PCa. Acoustic Radiation Force Impulse (ARFI) imaging has the potential to aid PCa diagnosis and management by using tissue stiffness to evaluate prostate zonal anatomy and lesions. MR and B-mode/ARFI in vivo imaging datasets were compared with one another and with gross pathology measurements made immediately after radical prostatectomy. Images were manually segmented in 3D Slicer to delineate the central gland (CG) and prostate capsule, and 3D models were rendered to evaluate zonal anatomy dimensions and volumes. Both imaging modalities showed good correlation between estimated organ volume and gross pathologic weights. Ultrasound and MR total prostate volumes were well correlated (R2 = 0.77), but B-mode images yielded prostate volumes that were larger (16.82% ± 22.45%) than MR images, due to overestimation of the lateral dimension (18.4% ± 13.9%), with less significant differences in the other dimensions (7.4% ± 17.6%, anterior-to-posterior, and −10.8% ± 13.9%, apex-to-base). ARFI and MR CG volumes were also well correlated (R2 = 0.85). CG volume differences were attributed to ARFI underestimation of the apex-to-base axis (−28.8% ± 9.4%) and ARFI overestimation of the lateral dimension (21.5% ± 14.3%). B-mode/ARFI imaging yielded prostate volumes and dimensions that were well correlated with MR T2-weighted image (T2WI) estimates, with biases in the lateral dimension due to poor contrast caused by extraprostatic fat. B-mode combined with ARFI imaging is a promising low-cost, portable, real-time modality that can complement mpMRI for PCa diagnosis, treatment planning, and management. PMID:25060914

  17. Response of electroexplosive devices to impulsive waveforms.

    NASA Technical Reports Server (NTRS)

    Rosenthal, L. A.; Menichelli, V. J.

    1971-01-01

    The firing characteristics of insensitive electroexplosive devices to certain impulsive waveforms have been investigated. For these waveforms, energy is delivered in a time short compared to the thermal time constant and therefore cooling plays a negligible role. One waveform is a terminated capacitor discharge wherein the regular discharge of a capacitor is terminated at a preset point. Another is a half-sine wave pulse. The theory, design, and application of both impulsive waveform generators are presented together with certain limited experimental observations.

  18. Toward global mapping of river discharge using satellite images and at-many-stations hydraulic geometry

    PubMed Central

    Gleason, Colin J.; Smith, Laurence C.

    2014-01-01

    Rivers provide critical water supply for many human societies and ecosystems, yet global knowledge of their flow rates is poor. We show that useful estimates of absolute river discharge (in cubic meters per second) may be derived solely from satellite images, with no ground-based or a priori information whatsoever. The approach works owing to discovery of a characteristic scaling law uniquely fundamental to natural rivers, here termed a river’s at-many-stations hydraulic geometry. A first demonstration using Landsat Thematic Mapper images over three rivers in the United States, Canada, and China yields absolute discharges agreeing to within 20–30% of traditional in situ gauging station measurements and good tracking of flow changes over time. Within such accuracies, the door appears open for quantifying river resources globally with repeat imaging, both retroactively and henceforth into the future, with strong implications for water resource management, food security, ecosystem studies, flood forecasting, and geopolitics. PMID:24639551

  19. Toward global mapping of river discharge using satellite images and at-many-stations hydraulic geometry.

    PubMed

    Gleason, Colin J; Smith, Laurence C

    2014-04-01

    Rivers provide critical water supply for many human societies and ecosystems, yet global knowledge of their flow rates is poor. We show that useful estimates of absolute river discharge (in cubic meters per second) may be derived solely from satellite images, with no ground-based or a priori information whatsoever. The approach works owing to discovery of a characteristic scaling law uniquely fundamental to natural rivers, here termed a river's at-many-stations hydraulic geometry. A first demonstration using Landsat Thematic Mapper images over three rivers in the United States, Canada, and China yields absolute discharges agreeing to within 20-30% of traditional in situ gauging station measurements and good tracking of flow changes over time. Within such accuracies, the door appears open for quantifying river resources globally with repeat imaging, both retroactively and henceforth into the future, with strong implications for water resource management, food security, ecosystem studies, flood forecasting, and geopolitics.

  20. Toward global mapping of river discharge using satellite images and at-many-stations hydraulic geometry.

    PubMed

    Gleason, Colin J; Smith, Laurence C

    2014-04-01

    Rivers provide critical water supply for many human societies and ecosystems, yet global knowledge of their flow rates is poor. We show that useful estimates of absolute river discharge (in cubic meters per second) may be derived solely from satellite images, with no ground-based or a priori information whatsoever. The approach works owing to discovery of a characteristic scaling law uniquely fundamental to natural rivers, here termed a river's at-many-stations hydraulic geometry. A first demonstration using Landsat Thematic Mapper images over three rivers in the United States, Canada, and China yields absolute discharges agreeing to within 20-30% of traditional in situ gauging station measurements and good tracking of flow changes over time. Within such accuracies, the door appears open for quantifying river resources globally with repeat imaging, both retroactively and henceforth into the future, with strong implications for water resource management, food security, ecosystem studies, flood forecasting, and geopolitics. PMID:24639551

  1. Low Pretreatment Acoustic Radiation Force Impulse Imaging (ARFI) Values Predict Sustained Virological Response in Antiviral Hepatitis C Virus (HCV) Therapy

    PubMed Central

    Zopf, Steffen; Rösch, Lara; Konturek, Peter C.; Goertz, Ruediger S.; Neurath, Markus F.; Strobel, Deike

    2016-01-01

    Background Non-invasive procedures such as acoustic radiation force impulse imaging (ARFI) shear-wave elastography are currently used for the assessment of liver fibrosis. In the course of chronic hepatitis C, significant liver fibrosis or cirrhosis develops in approximately 25% of patients, which is a negative predictor of antiviral treatment response. Cirrhosis can be prevented by successful virus elimination. In this prospective study, a pretreatment ARFI cutoff value of 1.5 m/s was evaluated in relation to sustained virological response to anti-HCV therapy. Material/Methods In 23 patients with chronic hepatitis C, liver stiffness was examined with ARFI at defined times before and under antiviral triple therapy (peginterferon, ribavirin in combination with a first-generation protease inhibitor, and telaprevir or boceprevir). Patients were stratified into 2 groups based on pretreatment ARFI values (<1.5 m/s and ≥1.5 m/s) for the assessment of virological response. Results The liver stiffness at baseline for all patients was 1.57±0.79 m/s (ARFI median ± standard deviation; margin: 0.81 m/s to 3.45 m/s). At week 4 of triple therapy, patients with low pretreatment ARFI values had higher rates of HCV-RNA negativity (69% vs. 43%), reflecting an early rapid virological response (eRVR). Sustained virological response (SVR) was found in 75% (12/16) of patients with an ARFI value <1.5 m/s and only 57% (4/7) of patients with ARFI value ≥1.5 m/s. Conclusions Patients with chronic hepatitis C and pretreatment ARFI <1.5 m/s showed earlier virus elimination and better response to treatment. PMID:27690214

  2. Three-Dimensional ISAR Imaging Method for High-Speed Targets in Short-Range Using Impulse Radar Based on SIMO Array

    PubMed Central

    Zhou, Xinpeng; Wei, Guohua; Wu, Siliang; Wang, Dawei

    2016-01-01

    This paper proposes a three-dimensional inverse synthetic aperture radar (ISAR) imaging method for high-speed targets in short-range using an impulse radar. According to the requirements for high-speed target measurement in short-range, this paper establishes the single-input multiple-output (SIMO) antenna array, and further proposes a missile motion parameter estimation method based on impulse radar. By analyzing the motion geometry relationship of the warhead scattering center after translational compensation, this paper derives the receiving antenna position and the time delay after translational compensation, and thus overcomes the shortcomings of conventional translational compensation methods. By analyzing the motion characteristics of the missile, this paper estimates the missile’s rotation angle and the rotation matrix by establishing a new coordinate system. Simulation results validate the performance of the proposed algorithm. PMID:26978372

  3. Three-Dimensional ISAR Imaging Method for High-Speed Targets in Short-Range Using Impulse Radar Based on SIMO Array.

    PubMed

    Zhou, Xinpeng; Wei, Guohua; Wu, Siliang; Wang, Dawei

    2016-03-11

    This paper proposes a three-dimensional inverse synthetic aperture radar (ISAR) imaging method for high-speed targets in short-range using an impulse radar. According to the requirements for high-speed target measurement in short-range, this paper establishes the single-input multiple-output (SIMO) antenna array, and further proposes a missile motion parameter estimation method based on impulse radar. By analyzing the motion geometry relationship of the warhead scattering center after translational compensation, this paper derives the receiving antenna position and the time delay after translational compensation, and thus overcomes the shortcomings of conventional translational compensation methods. By analyzing the motion characteristics of the missile, this paper estimates the missile's rotation angle and the rotation matrix by establishing a new coordinate system. Simulation results validate the performance of the proposed algorithm.

  4. Television image of a large upward electrical discharge above a thunderstorm system.

    PubMed

    Franz, R C; Nemzek, R J; Winckler, J R

    1990-07-01

    An image of an unusual luminous electrical discharge over a thunderstorm 250 kilometers from the observing site has been obtained with a low-light-level television camera. The discharge began at the cloud tops at 14 kilometers and extended into the clear air 20 kilometers higher. The image, which had a duration of less than 30 milliseconds,resembled two jets or fountains and was probably caused by two localizd electric charge concentrations at the cloud tops. Large upward discharges may create a hazard for aircraft and rocket launches and, by penetrating into the ionosphere, may initiate whistler waves and other effects on a magnetospheric scale. Such upward electrical discharges may account for unexplained photometric observations of distant lightning events that showed a low rise rate of the luminous pulse and no electromagnetic sferic pulse of the type that accompanies cloud-to-earth lightning strokes. An unusually high rate of such photometric events was recorded during the night of 22 to 23 September 1989 during a storm associated with hurricane Hugo.

  5. Particle visualization in high-power impulse magnetron sputtering. I. 2D density mapping

    SciTech Connect

    Britun, Nikolay Palmucci, Maria; Konstantinidis, Stephanos; Snyders, Rony

    2015-04-28

    Time-resolved characterization of an Ar-Ti high-power impulse magnetron sputtering discharge has been performed. This paper deals with two-dimensional density mapping in the discharge volume obtained by laser-induced fluorescence imaging. The time-resolved density evolution of Ti neutrals, singly ionized Ti atoms (Ti{sup +}), and Ar metastable atoms (Ar{sup met}) in the area above the sputtered cathode is mapped for the first time in this type of discharges. The energetic characteristics of the discharge species are additionally studied by Doppler-shift laser-induced fluorescence imaging. The questions related to the propagation of both the neutral and ionized discharge particles, as well as to their spatial density distributions, are discussed.

  6. Gas discharge visualization: an imaging and modeling tool for medical biometrics.

    PubMed

    Kostyuk, Nataliya; Cole, Phyadragren; Meghanathan, Natarajan; Isokpehi, Raphael D; Cohly, Hari H P

    2011-01-01

    The need for automated identification of a disease makes the issue of medical biometrics very current in our society. Not all biometric tools available provide real-time feedback. We introduce gas discharge visualization (GDV) technique as one of the biometric tools that have the potential to identify deviations from the normal functional state at early stages and in real time. GDV is a nonintrusive technique to capture the physiological and psychoemotional status of a person and the functional status of different organs and organ systems through the electrophotonic emissions of fingertips placed on the surface of an impulse analyzer. This paper first introduces biometrics and its different types and then specifically focuses on medical biometrics and the potential applications of GDV in medical biometrics. We also present our previous experience with GDV in the research regarding autism and the potential use of GDV in combination with computer science for the potential development of biological pattern/biomarker for different kinds of health abnormalities including cancer and mental diseases.

  7. Gas Discharge Visualization: An Imaging and Modeling Tool for Medical Biometrics

    PubMed Central

    Kostyuk, Nataliya; Cole, Phyadragren; Meghanathan, Natarajan; Isokpehi, Raphael D.; Cohly, Hari H. P.

    2011-01-01

    The need for automated identification of a disease makes the issue of medical biometrics very current in our society. Not all biometric tools available provide real-time feedback. We introduce gas discharge visualization (GDV) technique as one of the biometric tools that have the potential to identify deviations from the normal functional state at early stages and in real time. GDV is a nonintrusive technique to capture the physiological and psychoemotional status of a person and the functional status of different organs and organ systems through the electrophotonic emissions of fingertips placed on the surface of an impulse analyzer. This paper first introduces biometrics and its different types and then specifically focuses on medical biometrics and the potential applications of GDV in medical biometrics. We also present our previous experience with GDV in the research regarding autism and the potential use of GDV in combination with computer science for the potential development of biological pattern/biomarker for different kinds of health abnormalities including cancer and mental diseases. PMID:21747817

  8. Anatomy of a SAR impulse response.

    SciTech Connect

    Doerry, Armin Walter

    2007-08-01

    A principal measure of Synthetic Aperture Radar (SAR) image quality is the manifestation in the SAR image of a spatial impulse, that is, the SAR's Impulse Response (IPR). IPR requirements direct certain design decisions in a SAR. Anomalies in the IPR can point to specific anomalous behavior in the radar's hardware and/or software.

  9. A New Image Based Approach to Measure Discharge and Soil Saturation

    NASA Astrophysics Data System (ADS)

    Kaplan, Nils; Weiler, Markus; Blume, Theresa

    2016-04-01

    Discharge measurements are crucial for most hydrological studies. It is common to monitor discharge by recording water level and calculate the actual discharge using a rating curve that has been previously determined for varying flow conditions. Bubble and float gauges as well as radar based gauges are frequently used to measure water level. Recently particle image velocimetry (PIV) approaches have become more attractive due to continuous improvement of sensors and computing power. Standard cameras can be easily usable and cheap monitoring devices for discharge measurement. The combination of a camera and a staff gauge has been proved to be suitable for hydrological monitoring in several studies and is promoted as redundant backup as well as independent system. Our new image based system offers the possibility to measure water velocity and soil saturation in addition to water level. We use a commercial wildlife camera with sensors in the visible and infrared spectrum, allowing for day and night images. The system can be used for three purposes. (1) Water level measurement with a specifically built gauging plate. (2) A carbon fiber stick installed instream allows water velocity measurements. Water velocity can be derived from the bending of the carbon fiber under water pressure which is proportional to the water velocity and water level. Hence we can derive a rating curve between bending angle of the carbon fiber stick and the water velocity. Therefore we can constantly measure the water velocity and do not depend on traditional rating curves. (3) Soil water saturation is measured by perforated PVC bottles that enable water in- and outflow. Rising water level in the PVC-bottle will lift an integrated floating body that pushes up a detection marker visible for the camera above the ground. The measurement system is tested for monitoring intermittent streams in the Attert basin in Luxemburg linking the dynamics of the stream network extent to the surface connectivity

  10. Ptychographic imaging with a compact gas-discharge plasma extreme ultraviolet light source.

    PubMed

    Odstrcil, M; Bussmann, J; Rudolf, D; Bresenitz, R; Miao, Jianwei; Brocklesby, W S; Juschkin, L

    2015-12-01

    We report the demonstration of a scanning probe coherent diffractive imaging method (also known as ptychographic CDI) using a compact and partially coherent gas-discharge plasma source of extreme ultraviolet (EUV) radiation at a 17.3 nm wavelength. Until now, CDI has been mainly carried out with coherent, high-brightness light sources, such as third generation synchrotrons, x-ray free-electron lasers, and high harmonic generation. Here we performed ptychographic lensless imaging of an extended sample using a compact, lab-scale source. The CDI reconstructions were achieved by applying constraint relaxation to the CDI algorithm. Experimental results indicate that our method can handle the low spatial coherence and broadband nature of the EUV illumination, as well as the residual background due to visible light emitted by the gas-discharge source. The ability to conduct ptychographic imaging with lab-scale and partially coherent EUV sources is expected to significantly expand the applications of this powerful CDI method. PMID:26625054

  11. Pāhoehoe flow cooling, discharge, and coverage rates from thermal image chronometry

    USGS Publications Warehouse

    Dehn, Jonathan; Hamilton, Christopher M.; Harris, A. J. L.; Herd, Richard A.; James, M.R.; Lodato, Luigi; Steffke, Andrea

    2007-01-01

    Theoretically- and empirically-derived cooling rates for active pāhoehoe lava flows show that surface cooling is controlled by conductive heat loss through a crust that is thickening with the square root of time. The model is based on a linear relationship that links log(time) with surface cooling. This predictable cooling behavior can be used assess the age of recently emplaced sheet flows from their surface temperatures. Using a single thermal image, or image mosaic, this allows quantification of the variation in areal coverage rates and lava discharge rates over 48 hour periods prior to image capture. For pāhoehoe sheet flow at Kīlauea (Hawai`i) this gives coverage rates of 1–5 m2/min at discharge rates of 0.01–0.05 m3/s, increasing to ∼40 m2/min at 0.4–0.5 m3/s. Our thermal chronometry approach represents a quick and easy method of tracking flow advance over a three-day period using a single, thermal snap-shot.

  12. Ptychographic imaging with a compact gas-discharge plasma extreme ultraviolet light source.

    PubMed

    Odstrcil, M; Bussmann, J; Rudolf, D; Bresenitz, R; Miao, Jianwei; Brocklesby, W S; Juschkin, L

    2015-12-01

    We report the demonstration of a scanning probe coherent diffractive imaging method (also known as ptychographic CDI) using a compact and partially coherent gas-discharge plasma source of extreme ultraviolet (EUV) radiation at a 17.3 nm wavelength. Until now, CDI has been mainly carried out with coherent, high-brightness light sources, such as third generation synchrotrons, x-ray free-electron lasers, and high harmonic generation. Here we performed ptychographic lensless imaging of an extended sample using a compact, lab-scale source. The CDI reconstructions were achieved by applying constraint relaxation to the CDI algorithm. Experimental results indicate that our method can handle the low spatial coherence and broadband nature of the EUV illumination, as well as the residual background due to visible light emitted by the gas-discharge source. The ability to conduct ptychographic imaging with lab-scale and partially coherent EUV sources is expected to significantly expand the applications of this powerful CDI method.

  13. Schlieren imaging in a dielectric barrier discharge actuator for airflow control

    NASA Astrophysics Data System (ADS)

    Cristofolini, A.; Neretti, G.; Roveda, F.; Borghi, C. A.

    2012-02-01

    The operation of a surface dielectric barrier discharge actuator for airflow control has been experimentally investigated. The actuator is constituted by an electrode pair separated by a dielectric Teflon sheet. Several ac supply conditions have been utilized. An electrohydrodynamics interaction was induced in still air, and several fluid-dynamic regimes were obtained. Visualization of the plasma boundary layer during the discharge ignition phase and during the steady state regime was obtained by utilizing a Schlieren diagnostic technique. The vortex morphology and propagation velocities at all supply conditions utilized have been evaluated. Velocity profiles perpendicular to the actuator surface, obtained from Pitot tube measurements, and line intensity profiles, determined by means of Schlieren imaging, have been determined for the steady regime operation. The integral along a line perpendicular to the actuator surface of the light intensity of the Schlieren image has been calculated. The profile obtained is in good agreement with the Pitot velocity profile in all the supply conditions investigated. Numerical simulations were also performed. The calculations confirm the relation between the flow velocity distribution in the boundary layer and the gas density distribution, which is the cause of the Schlieren image.

  14. Association of ventral striatum monoamine oxidase-A binding and functional connectivity in antisocial personality disorder with high impulsivity: A positron emission tomography and functional magnetic resonance imaging study.

    PubMed

    Kolla, Nathan J; Dunlop, Katharine; Downar, Jonathan; Links, Paul; Bagby, R Michael; Wilson, Alan A; Houle, Sylvain; Rasquinha, Fawn; Simpson, Alexander I; Meyer, Jeffrey H

    2016-04-01

    Impulsivity is a core feature of antisocial personality disorder (ASPD) associated with abnormal brain function and neurochemical alterations. The ventral striatum (VS) is a key region of the neural circuitry mediating impulsive behavior, and low monoamine oxidase-A (MAO-A) level in the VS has shown a specific relationship to the impulsivity of ASPD. Because it is currently unknown whether phenotypic MAO-A markers can influence brain function in ASPD, we investigated VS MAO-A level and the functional connectivity (FC) of two seed regions, superior and inferior VS (VSs, VSi). Nineteen impulsive ASPD males underwent [(11)C] harmine positron emission tomography scanning to measure VS MAO-A VT, an index of MAO-A density, and resting-state functional magnetic resonance imaging that assessed the FC of bilateral seed regions in the VSi and VSs. Subjects also completed self-report impulsivity measures. Results revealed functional coupling of the VSs with bilateral dorsomedial prefrontal cortex (DMPFC) that was correlated with VS MAO-A VT (r=0.47, p=0.04), and functional coupling of the VSi with right hippocampus that was anti-correlated with VS MAO-A VT (r=-0.55, p=0.01). Additionally, VSs-DMPFC FC was negatively correlated with NEO Personality Inventory-Revised impulsivity (r=-0.49, p=0.03), as was VSi-hippocampus FC with Barratt Impulsiveness Scale-11 motor impulsiveness (r=-0.50, p=0.03). These preliminary results highlight an association of VS MAO-A level with the FC of striatal regions linked to impulsive behavior in ASPD and suggest that phenotype-based brain markers of ASPD have relevance to understanding brain function.

  15. Association of ventral striatum monoamine oxidase-A binding and functional connectivity in antisocial personality disorder with high impulsivity: A positron emission tomography and functional magnetic resonance imaging study.

    PubMed

    Kolla, Nathan J; Dunlop, Katharine; Downar, Jonathan; Links, Paul; Bagby, R Michael; Wilson, Alan A; Houle, Sylvain; Rasquinha, Fawn; Simpson, Alexander I; Meyer, Jeffrey H

    2016-04-01

    Impulsivity is a core feature of antisocial personality disorder (ASPD) associated with abnormal brain function and neurochemical alterations. The ventral striatum (VS) is a key region of the neural circuitry mediating impulsive behavior, and low monoamine oxidase-A (MAO-A) level in the VS has shown a specific relationship to the impulsivity of ASPD. Because it is currently unknown whether phenotypic MAO-A markers can influence brain function in ASPD, we investigated VS MAO-A level and the functional connectivity (FC) of two seed regions, superior and inferior VS (VSs, VSi). Nineteen impulsive ASPD males underwent [(11)C] harmine positron emission tomography scanning to measure VS MAO-A VT, an index of MAO-A density, and resting-state functional magnetic resonance imaging that assessed the FC of bilateral seed regions in the VSi and VSs. Subjects also completed self-report impulsivity measures. Results revealed functional coupling of the VSs with bilateral dorsomedial prefrontal cortex (DMPFC) that was correlated with VS MAO-A VT (r=0.47, p=0.04), and functional coupling of the VSi with right hippocampus that was anti-correlated with VS MAO-A VT (r=-0.55, p=0.01). Additionally, VSs-DMPFC FC was negatively correlated with NEO Personality Inventory-Revised impulsivity (r=-0.49, p=0.03), as was VSi-hippocampus FC with Barratt Impulsiveness Scale-11 motor impulsiveness (r=-0.50, p=0.03). These preliminary results highlight an association of VS MAO-A level with the FC of striatal regions linked to impulsive behavior in ASPD and suggest that phenotype-based brain markers of ASPD have relevance to understanding brain function. PMID:26908392

  16. The Rightful Role of MRI after Negative Conventional Imaging in the Management of Bloody Nipple Discharge.

    PubMed

    Sanders, Linda M; Daigle, Megan

    2016-01-01

    Nipple discharge is a frequent presenting complaint at breast clinics. Bloody nipple discharge (BND) has the highest risk of malignancy, albeit low. If mammogram and ultrasound are unrevealing, central duct excision (CDE) has been considered the gold standard in its management. Magnetic resonance imaging (MRI) has been widely confirmed as a highly sensitive test for detection of breast cancer, with an accompanying high negative predictive value. This article presents a retrospective review of patients with BND and negative conventional imaging, comparing outcome of patients who went directly to CDE without MRI to those patients who underwent preoperative MRI. Of 115 patients who underwent mammography and US alone prior to CDE, eight cancers were detected (seven ductal carcinoma in situ [DCIS] and 1 IDC, 7 mm [T1b]; incidence: 7%). Of 85 patients who underwent conventional imaging followed by MRI prior to surgery, eight cancers were detected (all DCIS; incidence: 9.4%), seven of which were identified by MRI. The one false-negative MRI had subtle findings which, in retrospect, were misinterpreted; however, a clinically apparent nipple lesion prompted surgical biopsy. Of 56 patients with a negative or benign MRI, CDE was negative for malignancy in all but that one patient. Sensitivity and specificity were 87.5%/71.4%. Positive predictive value and negative predictive value (NPV) were 24.1%/98.2%. MRI should be performed in all patients with BND and negative conventional imaging. The extremely high NPV of MRI suggests that a negative study could obviate CDE in most patients unless overriding clinical factors prevail. PMID:26684050

  17. Dopamine-Agonists and Impulsivity in Parkinson’s Disease: Impulsive Choices vs. Impulsive Actions

    PubMed Central

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

    2014-01-01

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

  18. High-speed imaging of traveling waves in a granular material during silo discharge.

    PubMed

    Börzsönyi, Tamás; Kovács, Zsolt

    2011-03-01

    We report experimental observations of sound waves in a granular material during resonant silo discharge called silo music. The grain motion was tracked by high-speed imaging while the resonance of the silo was detected by accelerometers and acoustic methods. The grains do not oscillate in phase at neighboring vertical locations, but information propagates upward in this system in the form of sound waves. We show that the wave velocity is not constant throughout the silo but considerably increases toward the lower end of the system, suggesting increased pressure in this region, where the flow changes from cylindrical to converging flow. In the upper part of the silo the wave velocity matches the sound velocity measured in the same material when standing (in the absence of flow). Grain oscillations show a stick-slip character only in the upper part of the silo.

  19. Identifying Clinically Significant Prostate Cancers using 3-D In Vivo Acoustic Radiation Force Impulse Imaging with Whole-Mount Histology Validation.

    PubMed

    Palmeri, Mark L; Glass, Tyler J; Miller, Zachary A; Rosenzweig, Stephen J; Buck, Andrew; Polascik, Thomas J; Gupta, Rajan T; Brown, Alison F; Madden, John; Nightingale, Kathryn R

    2016-06-01

    Overly aggressive prostate cancer (PCa) treatment adversely affects patients and places an unnecessary burden on our health care system. The inability to identify and grade clinically significant PCa lesions is a factor contributing to excessively aggressive PCa treatment, such as radical prostatectomy, instead of more focal, prostate-sparing procedures such as cryotherapy and high-dose radiation therapy. We have performed 3-D in vivo B-mode and acoustic radiation force impulse (ARFI) imaging using a mechanically rotated, side-fire endorectal imaging array to identify regions suspicious for PCa in 29 patients being treated with radical prostatectomies for biopsy-confirmed PCa. Whole-mount histopathology analyses were performed to identify regions of clinically significant/insignificant PCa lesions, atrophy and benign prostatic hyperplasia. Regions of suspicion for PCa were reader-identified in ARFI images based on boundary delineation, contrast, texture and location. These regions of suspicion were compared with histopathology identified lesions using a nearest-neighbor regional localization approach. Of all clinically significant lesions identified on histopathology, 71.4% were also identified using ARFI imaging, including 79.3% of posterior and 33.3% of anterior lesions. Among the ARFI-identified lesions, 79.3% corresponded to clinically significant PCa lesions, with these lesions having higher indices of suspicion than clinically insignificant PCa. ARFI imaging had greater sensitivity for posterior versus anterior lesions because of greater displacement signal-to-noise ratio and finer spatial sampling. Atrophy and benign prostatic hyperplasia can cause appreciable prostate anatomy distortion and heterogeneity that confounds ARFI PCa lesion identification; however, in general, ARFI regions of suspicion did not coincide with these benign pathologies. PMID:26947445

  20. Impulsive phase transport

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  1. Mastectomy - discharge

    MedlinePlus

    Breast removal surgery - discharge; Nipple-sparing mastectomy - discharge; Total mastectomy - discharge; Simple mastectomy - discharge; Modified radical mastectomy - discharge; Breast cancer - mastectomy -discharge

  2. [Affective disorders and impulsivity].

    PubMed

    Belzeaux, R; Correard, N; Mazzola-Pomietto, P; Adida, M; Cermolacce, M; Azorin, J-M

    2014-12-01

    Impulsivity is a complex and important phenomenon in mood disorders. Impulse control disorders, as defined in DSM, are more frequent in mood disorders especially in Bipolar Disorder type I, and are associated with a more severe course of illness. Dimensional studies demonstrate that impulsivity is a core manifestation of bipolar disorder both as state- and trait-dependent markers in patients. Comorbid substance use disorders are often associated with a higher level of impulsivity whereas the relation between suicidal behaviors and higher impulsivity remains uncertain. Moreover, neuropsychological tests were used to study correlation between clinical impulsivity and laboratory measurements of impulsivity. Level of correlation remains weak and several explanations are proposed in the literature.

  3. Genetics of impulsive behaviour

    PubMed Central

    Bevilacqua, Laura; Goldman, David

    2013-01-01

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

  4. Virtual touch tissue imaging on acoustic radiation force impulse elastography: a new technique for differential diagnosis between benign and malignant thyroid nodules.

    PubMed

    Zhang, Yi-Feng; He, Yong; Xu, Hui-Xiong; Xu, Xiao-Hong; Liu, Chang; Guo, Le-Hang; Liu, Lin-Na; Xu, Jun-Mei

    2014-04-01

    Objectives- Acoustic radiation force impulse elastography is a newly developed ultrasound elasticity imaging technique that included both Virtual Touch tissue quantification and Virtual Touch tissue imaging (VTI; Siemens Medical Solutions, Mountain View, CA). This study aimed to evaluate the usefulness of VTI in differentiating malignant from benign thyroid nodules. Methods- This study included 192 consecutive patients with thyroid nodules (n = 219) who underwent surgery for compressive symptoms or suspicion of malignancy. Tissue stiffness on VTI elastography was scored from 1 (soft) to 6 (hard). The VTI scores between malignant and benign thyroid nodules were compared. The intraobserver and interobserver agreement for VTI elastography was also assessed. Results- On VTI elastography: score 1 was found in 84 nodules (all benign); score 2 in 37 nodules (3 papillary carcinomas and 34 benign nodules); score 3 in 25 nodules (1 medullary carcinoma, 6 papillary carcinomas, and 18 benign nodules); score 4 in 53 nodules (50 papillary carcinomas and 3 benign nodules); score 5 in 17 nodules (14 papillary carcinomas and 3 benign nodules); and score 6 in 3 nodules (all papillary carcinomas). A VTI elasticity score of 4 or greater was highly predictive of malignancy (P< .01), and the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 87.0% (67 of 77), 95.8% (136 of 142), 91.8% (67 of 73), 93.1% (136 of 146), and 92.7% (203 of 219), respectively. The κ values were 0.69 for intraobserver agreement and 0.85 for interobserver agreement. Conclusions- Virtual Touch tissue elasticity imaging has great potential as an adjunctive tool combined with conventional sonography for differential diagnosis between benign and malignant thyroid nodules.

  5. Obstacle avoidance and concealed target detection using the Army Research Lab ultra-wideband synchronous impulse reconstruction (UWB SIRE) forward imaging radar

    NASA Astrophysics Data System (ADS)

    Nguyen, Lam; Wong, David; Ressler, Marc; Koenig, Francois; Stanton, Brian; Smith, Gregory; Sichina, Jeffrey; Kappra, Karl

    2007-04-01

    The U.S. Army Research Laboratory (ARL), as part of a mission and customer funded exploratory program, has developed a new low-frequency, ultra-wideband (UWB) synthetic aperture radar (SAR) for forward imaging to support the Army's vision of an autonomous navigation system for robotic ground vehicles. These unmanned vehicles, equipped with an array of imaging sensors, will be tasked to help detect man-made obstacles such as concealed targets, enemy minefields, and booby traps, as well as other natural obstacles such as ditches, and bodies of water. The ability of UWB radar technology to help detect concealed objects has been documented in the past and could provide an important obstacle avoidance capability for autonomous navigation systems, which would improve the speed and maneuverability of these vehicles and consequently increase the survivability of the U. S. forces on the battlefield. One of the primary features of the radar is the ability to collect and process data at combat pace in an affordable, compact, and lightweight package. To achieve this, the radar is based on the synchronous impulse reconstruction (SIRE) technique where several relatively slow and inexpensive analog-to-digital (A/D) converters are used to sample the wide bandwidth of the radar signals. We conducted an experiment this winter at Aberdeen Proving Ground (APG) to support the phenomenological studies of the backscatter from positive and negative obstacles for autonomous robotic vehicle navigation, as well as the detection of concealed targets of interest to the Army. In this paper, we briefly describe the UWB SIRE radar and the test setup in the experiment. We will also describe the signal processing and the forward imaging techniques used in the experiment. Finally, we will present imagery of man-made obstacles such as barriers, concertina wires, and mines.

  6. Impulsive action: emotional impulses and their control

    PubMed Central

    Frijda, Nico H.; Ridderinkhof, K. Richard; Rietveld, Erik

    2014-01-01

    This paper presents a novel theoretical view on impulsive action, integrating thus far separate perspectives on non-reflective action, motivation, emotion regulation, and impulse control. We frame impulsive action in terms of directedness of the individual organism toward, away, or against other givens – toward future states and away from one’s present state. First, appraisal of a perceived or thought-of event or object on occasion, rapidly and without premonition or conscious deliberation, triggers a motive to modify one’s relation to that event or object. Situational specifics of the event as perceived and appraised motivate and guide selection of readiness for a particular kind of purposive action. Second, perception of complex situations can give rise to multiple appraisals, multiple motives, and multiple simultaneous changes in action readiness. Multiple states of action readiness may interact in generating action, by reinforcing or attenuating each other, thereby yielding impulse control. We show how emotion control can itself result from a motive state or state of action readiness. Our view links impulsive action mechanistically to states of action readiness, which is the central feature of what distinguishes one kind of emotion from another. It thus provides a novel theoretical perspective to the somewhat fragmented literature on impulsive action. PMID:24917835

  7. Physical processes of image formation during gas-discharge visualization (the Kirlian effect) (Review)

    NASA Astrophysics Data System (ADS)

    Bankovskii, N. G.; Korotkov, K. G.; Petrov, N. N.

    1986-04-01

    A survey is made of previously published and original results on physical processes which determine Kirlian-effect visualization. Three types of gas-discharge visualization (GDV) are considered: (1) avalanche GDV, at atmospheric pressure and small discharge gaps; (2) surface GDV, at atmospheric pressure and a discharge sliding along the surface of a dielectric; and (3) 'vacuum' GDV, at reduced pressure and relatively large discharge gaps (of the order of a centimeter). The possibilities of the practical application of these techniques are assessed, and specific recommendations on their use are given.

  8. Acoustic radiation force impulse imaging with virtual touch tissue quantification: measurements of normal breast tissue and dependence on the degree of pre-compression.

    PubMed

    Wojcinski, Sebastian; Brandhorst, Kathrin; Sadigh, Gelareh; Hillemanns, Peter; Degenhardt, Friedrich

    2013-12-01

    Acoustic radiation force impulse imaging (ARFI) with Virtual Touch tissue quantification (VTTQ) enables the determination of shear wave velocity in meters per second (m/s). We investigated shear wave velocity in normal breast tissue and analyzed the influence of the degree of pre-compression on the measurements. In repeated measurements and with normal pre-compression, the mean shear wave velocity in breast parenchyma was significantly higher than that in breast adipose tissue (3.33 ± 1.18 m/s vs. 2.90 ± 1.10 m/s; p < 0.001; 712 measurements in 89 patients). Furthermore, we found a significant positive correlation between degree of pre-compression and velocity measurements. Shear wave velocities with low, moderate and high pre-compression were 1.89, 3.18 and 4.39 m/s in parenchyma, compared with 1.46, 2.55 and 3.64 m/s in adipose tissue, respectively (p < 0.001; 360 measurements in 60 patients). VTTQ of breast tissue is a feasible method with high accuracy; however, the degree of pre-compression applied may significantly influence the measurements.

  9. Evaluating the Feasibility of Acoustic Radiation Force Impulse Shear Wave Elasticity Imaging of the Uterine Cervix With an Intracavity Array: A Simulation Study

    PubMed Central

    Feltovich, Helen; Homyk, Andrew D.; Carlson, Lindsey C.; Hall, Timothy J.

    2015-01-01

    The uterine cervix softens, shortens, and dilates throughout pregnancy in response to progressive disorganization of its layered collagen microstructure. This process is an essential part of normal pregnancy, but premature changes are associated with preterm birth. Clinically, there are no reliable noninvasive methods to objectively measure cervical softening or assess cervical microstructure. The goal of these preliminary studies was to evaluate the feasibility of using an intracavity ultrasound array to generate acoustic radiation force impulse (ARFI) excitations in the uterine cervix through simulation, and to optimize the acoustic radiation force (ARF) excitation for shear wave elasticity imaging (SWEI) of the tissue stiffness. The cervix is a unique soft tissue target for SWEI because it has significantly greater acoustic attenuation (α = 1.3 to 2.0 dB·cm−1·MHz−1) than other soft tissues, and the pathology being studied tends to lead to an increase in tissue compliance, with healthy cervix being relatively stiff compared with other soft tissues (E ≈ 25 kPa). Additionally, the cervix can only be accessed in vivo using a transvaginal or catheter-based array, which places additional constraints on the excitation focal characteristics that can be used during SWEI. Finite element method (FEM) models of SWEI show that larger-aperture, catheter-based arrays can utilize excitation frequencies up to 7 MHz to generate adequate focal gain up to focal depths 10 to 15 mm deep, with higher frequencies suffering from excessive amounts of near-field acoustic attenuation. Using full-aperture excitations can yield ~40% increases in ARFI-induced displacements, but also restricts the depth of field of the excitation to ~0.5 mm, compared with 2 to 6 mm, which limits the range that can be used for shear wave characterization of the tissue. The center-frequency content of the shear wave particle velocity profiles ranges from 1.5 to 2.5 kHz, depending on the focal

  10. 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

  11. Imaging feedback for histotripsy by characterizing dynamics of acoustic radiation force impulse (ARFI)-induced shear waves excited in a treated volume.

    PubMed

    Wang, Tzu-Yin; Hall, Timothy L; Xu, Zhen; Fowlkes, J Brian; Cain, Charles A

    2014-07-01

    Our previous study indicated that shear waves decay and propagate at a lower speed as they propagate into a tissue volume mechanically fractionated by histotripsy. In this paper, we hypothesize that the change in the shear dynamics is related to the degree of tissue fractionation, and can be used to predict histotripsy treatment outcomes. To test this hypothesis, lesions with different degrees of tissue fractionation were created in agar-graphite tissue phantoms and ex vivo kidneys with increasing numbers of therapy pulses, from 0 to 2000 pulses per treatment location. The therapy pulses were 3-cycle 750-kHz focused ultrasound delivered at a peak negative/positive pressure of 17/108 MPa and a repetition rate of 50 Hz. The shear waves were excited by acoustic radiation force impulse (ARFI) focused at the center of the lesion. The spatial and temporal behavior of the propagating shear waves was measured with ultrasound plane wave imaging. The temporal displacement profile at a lateral location 10 mm offset to the shear excitation region was detected with M-mode imaging. The decay and delay of the shear waves were quantitatively characterized on the temporal displacement profile. Results showed significant changes in two characteristics on the temporal displacement profile: the peak-to-peak displacement decayed exponentially with increasing numbers of therapy pulses; the relative time-to-peak displacement increased with increasing numbers of therapy pulses, and appeared to saturate at higher numbers of pulses. Correspondingly, the degree of tissues fractionation, as indicated by the percentage of structurally intact cell nuclei, decreased exponentially with increasing numbers of therapy pulses. Strong linear correlations were found between the two characteristics and the degree of tissue fractionation. These results suggest that the characteristics of the shear temporal displacement profile may provide useful feedback information regarding the treatment outcomes.

  12. Nerve Impulses in Plants

    ERIC Educational Resources Information Center

    Blatt, F. J.

    1974-01-01

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

  13. Sensing through the wall imaging using the Army Research Lab ultra-wideband synchronous impulse reconstruction (UWB SIRE) radar

    NASA Astrophysics Data System (ADS)

    Nguyen, Lam; Ressler, Marc; Sichina, Jeffrey

    2008-04-01

    The U.S. Army Research Laboratory (ARL), as part of a mission and customer funded exploratory program, has developed a new low-frequency, ultra-wideband (UWB) synthetic aperture radar (SAR). The radar is capable of penetrating enclosed areas (buildings) and generating SAR imagery. This supports the U.S. Army's need for intelligence on the configuration, content, and human presence inside these enclosed areas. The radar system is mounted on a ground based vehicle traveling along the road and is configured with an array of antennas pointing toward the enclosed areas of interest. This paper will describe an experiment conducted recently at Aberdeen Proving Ground (APG), Maryland. In this paper we briefly describe the UWB SIRE radar and the test setup in the experiment. We will also describe the signal processing and the image techniques used to produce the SAR imagery. Finally, we will present SAR imagery of the building and its internal structure from different viewing directions.

  14. Uniform and non-uniform modes of nanosecond-pulsed dielectric barrier discharge in atmospheric air: fast imaging and spectroscopic measurements of electric field.

    PubMed

    Liu, Chong; Dobrynin, Danil; Fridman, Alexander

    2014-06-25

    In this study, we report experimental results on fast ICCD imaging of development of nanosecond-pulsed dielectric barrier discharge (DBD) in atmospheric air and spectroscopic measurements of electric field in the discharge. Uniformity of the discharge images obtained with nanosecond exposure times were analyzed using chi-square test. The results indicate that DBD uniformity strongly depends on applied (global) electric field in the discharge gap, and is a threshold phenomenon. We show that in the case of strong overvoltage on the discharge gap (provided by fast rise times), there is transition from filamentary to uniform DBD mode which correlates to the corresponding decrease of maximum local electric field in the discharge. PMID:25071294

  15. Uniform and non-uniform modes of nanosecond-pulsed dielectric barrier discharge in atmospheric air: fast imaging and spectroscopic measurements of electric field

    PubMed Central

    Liu, Chong; Dobrynin, Danil; Fridman, Alexander

    2014-01-01

    In this study, we report experimental results on fast ICCD imaging of development of nanosecond-pulsed dielectric barrier discharge (DBD) in atmospheric air and spectroscopic measurements of electric field in the discharge. Uniformity of the discharge images obtained with nanosecond exposure times were analyzed using chi-square test. The results indicate that DBD uniformity strongly depends on applied (global) electric field in the discharge gap, and is a threshold phenomenon. We show that in the case of strong overvoltage on the discharge gap (provided by fast rise times), there is transition from filamentary to uniform DBD mode which correlates to the corresponding decrease of maximum local electric field in the discharge. PMID:25071294

  16. A neurogenetic approach to impulsivity.

    PubMed

    Congdon, Eliza; Canli, Turhan

    2008-12-01

    Impulsivity is a complex and multidimensional trait that is of interest to both personality psychologists and to clinicians. For investigators seeking the biological basis of personality traits, the use of neuroimaging techniques such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) revolutionized personality psychology in less than a decade. Now, another revolution is under way, and it originates from molecular biology. Specifically, new findings in molecular genetics, the detailed mapping and the study of the function of genes, have shown that individual differences in personality traits can be related to individual differences within specific genes. In this article, we will review the current state of the field with respect to the neural and genetic basis of trait impulsivity.

  17. A Neurogenetic Approach to Impulsivity

    PubMed Central

    Congdon, Eliza; Canli, Turhan

    2008-01-01

    Impulsivity is a complex and multidimensional trait that is of interest to both personality psychologists and to clinicians. For investigators seeking the biological basis of personality traits, the use of neuroimaging techniques such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) revolutionized personality psychology in less than a decade. Now, another revolution is under way, and it originates from molecular biology. Specifically, new findings in molecular genetics, the detailed mapping and the study of the function of genes, have shown that individual differences in personality traits can be related to individual differences within specific genes. In this article, we will review the current state of the field with respect to the neural and genetic basis of trait impulsivity. PMID:19012655

  18. Impulsivity and Academic Cheating

    ERIC Educational Resources Information Center

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

    2009-01-01

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

  19. Rethinking Impulsivity in Suicide

    ERIC Educational Resources Information Center

    Klonsky, E. David; May, Alexis

    2010-01-01

    Elevated impulsivity is thought to facilitate the transition from suicidal thoughts to suicidal behavior. Therefore, impulsivity should distinguish those who have attempted suicide (attempters) from those who have only considered suicide (ideators-only). This hypothesis was examined in three large nonclinical samples: (1) 2,011 military recruits,…

  20. Rethinking impulsivity in suicide.

    PubMed

    Klonsky, E David; May, Alexis

    2010-12-01

    Elevated impulsivity is thought to facilitate the transition from suicidal thoughts to suicidal behavior. Therefore, impulsivity should distinguish those who have attempted suicide (attempters) from those who have only considered suicide (ideators-only). This hypothesis was examined in three large nonclinical samples: (1) 2,011 military recruits, (2) 1,296 college students, and (3) 399 high school students. In sample 1, contrary to traditional models of suicide risk, a unidimensional measure of impulsivity failed to distinguish attempters from ideators-only. In samples 2 and 3, which were administered a multidimensional measure of impulsivity (i.e., the UPPS impulsive behavior scale; Whiteside & Lynam, 2001), different impulsivity-related traits characterized attempters and ideators-only. Whereas both attempters and ideators-only exhibited high urgency (the tendency to act impulsive in the face of negative emotions), only attempters exhibited poor premeditation (a diminished ability to think through the consequences of one's actions). Neither attempters nor ideators-only exhibited high sensation seeking or lack of perseverance. Future research should continue to distinguish impulsivity-related traits that predict suicide ideation from those that predict suicide attempts, and models of suicide risk should be revised accordingly. PMID:21198330

  1. Impulsiveness in professional fighters.

    PubMed

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

    2014-01-01

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

  2. Evaluation of Acoustic Radiation Force Impulse Imaging (ARFI) for the Determination of Liver Stiffness Using Transient Elastography as a Reference in Children

    PubMed Central

    Sagir, A.; Ney, D.; Oh, J.; Pandey, S.; Kircheis, G.; Mayatepek, E.; Häussinger, D.

    2015-01-01

    Purpose: Transient elastography (Fibroscan©; (FS)) and acoustic radiation force impulse imaging (ARFI) represent noninvasive, user-friendly and quick methods providing an objective and reproducible measure of liver stiffness. The aim of the study was to evaluate cut-off values and performance of ARFI measurements in children using transient elastography as a reference. Methods/Patients: A total of 198 children were enrolled in this study. All patients underwent liver stiffness measurements with FS (FS-LS) as well as ARFI (with shear wave velocity quantification; ARFI-SWV) and the performance of ARFI in comparison to FS was studied. Results: Significantly higher rates of successful measurements were found for ARFI compared to FS (198/198 (100%) vs. 160/198 (80.8%); p<0.001). ARFI-SWV correlated significantly with FS-LS (r=0.751, p=0.001). ARFI-SWV increased significantly with the stage of fibrosis (1.19+0.15 m/s for patients with FS-LS<7.6 kPa); 1.34+0.22 m/s for patients with 7.613.0 kPa). ARFI-SWV cut-off values were identified for no significant fibrosis (1.31 m/s; sensitivity 61.8% and specificity 79.5%) and for liver cirrhosis (1.63 m/s; sensitivity 70.0% and specificity 97.4%). The median values of liver stiffness measured by FS were age-dependent in 90 children without liver diseases with 4.8, 5.6, and 5.7 kPa in children 0–5, 6–11, and 12–18 years, respectively.

  3. RAPID EVOLUTION OF THE SOLAR ATMOSPHERE DURING THE IMPULSIVE PHASE OF A MICROFLARE OBSERVED WITH THE EXTREME-ULTRAVIOLET IMAGING SPECTROMETER ABOARD HINODE: HINTS OF CHROMOSPHERIC MAGNETIC RECONNECTION

    SciTech Connect

    Brosius, Jeffrey W.

    2013-11-10

    We obtained rapid cadence (11.2 s) EUV stare spectra of a solar microflare with the Extreme-ultraviolet Imaging Spectrometer aboard Hinode. The intensities of lines formed at temperatures too cool to be found in the corona brightened by factors around 16 early during this event, indicating that we observed a site of energy deposition in the chromosphere. We derive the density evolution of the flare plasma at temperature around 2 MK from the intensity ratio of Fe XIV lines at 264.789 Å and 274.204 Å. From both lines we removed the bright pre-flare quiescent emission, and from 274.204 we removed the blended emission of Si VII λ274.180 based on the Si VII λ274.180/275.361 intensity ratio, which varies only slightly with density. In this way the flare electron density is derived with emission from only the flare plasma. The density increased by an order of magnitude from its pre-flare quiescent average of (3.43 ± 0.19) × 10{sup 9} cm{sup –3} to its maximum impulsive phase value of (3.04 ± 0.57) × 10{sup 10} cm{sup –3} in 2 minutes. The fact that this rapid increase in density is not accompanied by systematic, large upward velocities indicates that the density increase is not due to the filling of loops with evaporated chromospheric material, but rather due to material being directly heated in the chromosphere, likely by magnetic reconnection. The density increase may be due to a progression of reconnection sites to greater depths in the chromosphere, where it has access to larger densities, or it may be due to compression of 2 MK plasma by the 10 MK plasma as it attempts to expand against the high-density chromospheric plasma.

  4. Ion energies in high power impulse magnetron sputtering with and without localized ionization zones

    SciTech Connect

    Yang, Yuchen; Tanaka, Koichi; Liu, Jason; Anders, André

    2015-03-23

    High speed imaging of high power impulse magnetron sputtering discharges has revealed that ionization is localized in moving ionization zones but localization disappears at high currents for high yield targets. This offers an opportunity to study the effect ionization zones have on ion energies. We measure that ions have generally higher energies when ionization zones are present, supporting the concept that these zones are associated with moving potential humps. We propose that the disappearance of ionization zones is caused by an increased supply of atoms from the target which cools electrons and reduces depletion of atoms to be ionized.

  5. 2D Thermoluminescence imaging of dielectric surface long term charge memory of plasma surface interaction in DBD discharges

    NASA Astrophysics Data System (ADS)

    Ambrico, Paolo F.; Ambrico, Marianna; Schiavulli, Luigi; De Benedictis, Santolo

    2014-07-01

    The charge trapping effect due to the exposure of alumina surfaces to plasma has been studied in a volume dielectric barrier discharge (DBD) in Ar and He noble gases. The long lasting charge trapping of alumina dielectric plates, used as barriers in DBDs, is evidenced by an ex situ thermoluminescence (TL) experiment performed with a standard and a custom two-dimensional (2D)-TL apparatus. The spatial density of trapped surface charges is found to be strongly correlated to the plasma morphology, and the surface spatial memory lasted for several minutes to hours after plasma exposure. In the case of Ar, the plasma channel impact signature on the surface shows a higher equivalent radiation dose with respect to the surface plasma wave and the post-discharge species signature. As a consequence, for the development of discharges, inside the dielectric surface the availability of lower energy trapped electrons is larger in the first region of plasma impact. The reported spatial memory increases the likelihood of the occurrence of plasma filaments in the same position in different runs. In He plasmas, the dielectric barrier shows an almost uniform distribution of trapped charges, meaning that there is no preferred region for the development of the discharge. In all cases a slight asymmetry was shown in the direction of the gas flow. This can be interpreted as being due to the long-living species moving in the direction of the gas flow, corresponding with the TL side experiment on the sample exposed to the plasma afterglow. The maximum values and the integral of the 2D-TL images showed a linear relation with the total charge per ac cycle, corresponding with findings for the TL glow curve. In conclusion, 2D-TL images allow the retrieval of information regarding the plasma surface interaction such as the plasma morphology, trap sites and their activation temperature.

  6. Sub-wavelength resolution of MMW imaging systems using extremely inexpensive scanning Glow Discharge Detector (GDD) double row camera

    NASA Astrophysics Data System (ADS)

    Kopeika, N. S.; Abramovich, A.; Levanon, A.; Akram, A.; Rozban, D.; Yitzhaky, Y.; Yadid-Pecht, O.; Belenky, A.

    2012-06-01

    The properties of terahertz (THz) radiation are well known. They penetrate well most non-conducting media; there are no known biological hazards, and atmospheric attenuation and scattering is lower than visual and IR radiation. Thus THz imaging is very attractive for homeland security, biological, space, and industrial applications. In the other hand, the resolution of MMW images is lower comparing to IR and visual due to longer wavelength. Furthermore, the diffraction effects are more noticeable in THz and MMW imaging systems. Thus the MMW images are blurred and unclear and thus it is difficult to see the details and small objects. In recent experimental work with 8X8 Glow Discharge Detector (GDD) Focal Plane Array (FPA) we were able to improve the resolution of MMW images by using oversampling methods with basic DSP algorithms. In this work a super resolution method with basic DSP algorithms will be demonstrated using the 2X18 double row camera. MMW images with sub wavelength resolution will be shown using those methods and small details and small objects will be observed.

  7. Irresistible impulse: psychiatric viewpoint.

    PubMed

    Weil, F

    1989-01-01

    The responses of the psychiatric profession to the legal criteria applied to irresistible impulse in cases of psychotic offenders are examined. An illustrative case, and its legal consequences, support the desirability of the psychiatric approach.

  8. Impulsivity and methamphetamine use.

    PubMed

    Semple, Shirley J; Zians, Jim; Grant, Igor; Patterson, Thomas L

    2005-09-01

    The purpose of this study was to explore the relationship between methamphetamine (meth) use and impulsivity in a sample of 385 HIV-negative heterosexually identified meth users. Participants who scored highest on a self-report measure of impulsivity were compared with those who scored lower in terms of background characteristics, meth use patterns, use of alcohol and other illicit drugs, sexual risk behavior, and psychiatric health variables. Methamphetamine users in the high impulsivity group were younger, less educated, used larger quantities of meth, were more likely to be binge users, had a larger number of sexual partners, engaged in more unprotected vaginal and oral sex, and scored higher on the Beck Depression Inventory as compared with those in the low impulsivity group. In a logistic regression analysis, Beck depression was the factor that best distinguished between meth users who scored high and those who scored low on impulsivity. Neurophysiological pathways that may underlie the relationship between impulsivity and meth use are discussed. PMID:16135337

  9. Time-resolved imaging of electrical discharge development in underwater bubbles

    NASA Astrophysics Data System (ADS)

    Tu, Yalong; Xia, Hualei; Yang, Yong; Lu, Xinpei

    2016-01-01

    The formation and development of plasma in single air bubbles submerged in water were investigated. The difference in the discharge dynamics and the after-effects on the bubble were investigated using a 900 000 frame per second high-speed charge-coupled device camera. It was observed that depending on the position of the electrodes, the breakdown could be categorized into two modes: (1) direct discharge mode, where the high voltage and ground electrodes were in contact with the bubble, and the streamer would follow the shortest path and propagate along the axis of the bubble and (2) dielectric barrier mode, where the ground electrode was not in touch with the bubble surface, and the streamer would form along the inner surface of the bubble. The oscillation of the bubble and the development of instabilities on the bubble surface were also discussed.

  10. Neural substrates of time perception and impulsivity

    PubMed Central

    Wittmann, Marc; Simmons, Alan N.; Flagan, Taru; Lane, Scott D.; Wackermann, Jiří; Paulus, Martin P.

    2011-01-01

    Several studies provide empirical evidence for the association between impulsivity and time perception. However, little is known about the neural substrates underlying this function. This investigation examined the influence of impulsivity on neural activation patterns during the encoding and reproduction of intervals with durations of 3, 9 and 18 seconds using event-related functional magnetic resonance imaging (fMRI). Twenty-seven subjects participated in this study, including 15 high impulsive subjects that were classified based on their self-rating. FMRI activation during the duration reproduction task was correlated with measures of two self-report questionnaires related to the concept of impulsivity (Barratt Impulsiveness Scale, BIS; Zimbardo Time Perspective Inventory, ZTPI). Behaviorally, those individuals who under-reproduced temporal intervals also showed lower scores on the ZTPI future perspective subscale and higher scores on the BIS. FMRI activation revealed an accumulating pattern of neural activity peaking at the end of the 9- and 18-s interval within right posterior insula. Activations of brain regions during the reproduction phase of the timing task, such as those related to motor execution as well as to the ‘core control network’ – encompassing the inferior frontal and medial frontal cortex, the anterior insula as well as the inferior parietal cortex – were significantly correlated with reproduced duration, as well as with BIS and ZTPI subscales. In particular, the greater activation in these regions the shorter were the reproduced intervals, the more impulsive was an individual and the less pronounced the future perspective. Activation in the core control network, thus, may form a biological marker for cognitive time management and for impulsiveness. PMID:21763642

  11. Neural substrates of time perception and impulsivity.

    PubMed

    Wittmann, Marc; Simmons, Alan N; Flagan, Taru; Lane, Scott D; Wackermann, Jiří; Paulus, Martin P

    2011-08-11

    Several studies provide empirical evidence for the association between impulsivity and time perception. However, little is known about the neural substrates underlying this function. This investigation examined the influence of impulsivity on neural activation patterns during the encoding and reproduction of intervals with durations of 3, 9 and 18s using event-related functional magnetic resonance imaging (fMRI). Twenty-seven subjects participated in this study, including 15 high impulsive subjects that were classified based on their self-rating. FMRI activation during the duration reproduction task was correlated with measures of two self-report questionnaires related to the concept of impulsivity (Barratt Impulsiveness Scale, BIS; Zimbardo Time Perspective Inventory, ZTPI). Behaviorally, those individuals who under-reproduced temporal intervals also showed lower scores on the ZTPI future perspective subscale and higher scores on the BIS. FMRI activation revealed an accumulating pattern of neural activity peaking at the end of the 9- and 18-s intervals within right posterior insula. Activations of brain regions during the reproduction phase of the timing task, such as those related to motor execution as well as to the 'core control network' - encompassing the inferior frontal and medial frontal cortices, the anterior insula as well as the inferior parietal cortex - were significantly correlated with reproduced duration, as well as with BIS and ZTPI subscales. In particular, the greater activation in these regions the shorter were the reproduced intervals, the more impulsive was an individual and the less pronounced the future perspective. Activation in the core control network, thus, may form a biological marker for cognitive time management and for impulsiveness.

  12. Impulse-Momentum Diagrams

    NASA Astrophysics Data System (ADS)

    Rosengrant, David

    2011-01-01

    Multiple representations are a valuable tool to help students learn and understand physics concepts. Furthermore, representations help students learn how to think and act like real scientists.2 These representations include: pictures, free-body diagrams,3 energy bar charts,4 electrical circuits, and, more recently, computer simulations and animations.5 However, instructors have limited choices when they want to help their students understand impulse and momentum. One of the only available options is the impulse-momentum bar chart.6 The bar charts can effectively show the magnitude of the momentum as well as help students understand conservation of momentum, but they do not easily show the actual direction. This paper highlights a new representation instructors can use to help their students with momentum and impulse—the impulse-momentum diagram (IMD).

  13. Ballistic impulse gauge

    DOEpatents

    Ault, S.K.

    1993-12-21

    A gauge for detecting the impulse generated in sample materials by X-rays or other impulse producing mechanisms utilizes a pair of flat annular springs to support a plunger relative to a housing which may itself be supported by a pair of flat annular springs in a second housing. The plunger has a mounting plate mounted on one end and at the other, a position or velocity transducer is mounted. The annular springs consist of an outer ring and an inner ring with at least three arcuate members connecting the outer ring with the inner ring. 4 figures.

  14. Ballistic impulse gauge

    DOEpatents

    Ault, Stanley K.

    1993-01-01

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

  15. Draft tube discharge fluctuation during self-sustained pressure surge: fluorescent particle image velocimetry in two-phase flow

    NASA Astrophysics Data System (ADS)

    Müller, A.; Dreyer, M.; Andreini, N.; Avellan, F.

    2013-04-01

    Hydraulic machines play an increasingly important role in providing a secondary energy reserve for the integration of renewable energy sources in the existing power grid. This requires a significant extension of their usual operating range, involving the presence of cavitating flow regimes in the draft tube. At overload conditions, the self-sustained oscillation of a large cavity at the runner outlet, called vortex rope, generates violent periodic pressure pulsations. In an effort to better understand the nature of this unstable behavior and its interaction with the surrounding hydraulic and mechanical system, the flow leaving the runner is investigated by means of particle image velocimetry. The measurements are performed in the draft tube cone of a reduced scale model of a Francis turbine. A cost-effective method for the in-house production of fluorescent seeding material is developed and described, based on off-the-shelf polyamide particles and Rhodamine B dye. Velocity profiles are obtained at three streamwise positions in the draft tube cone, and the corresponding discharge variation in presence of the vortex rope is calculated. The results suggest that 5-10 % of the discharge in the draft tube cone is passing inside the vortex rope.

  16. Time-series observations of hydrothermal discharge using an acoustic imaging sonar: a NEPTUNE observatory case study

    NASA Astrophysics Data System (ADS)

    Xu, Guangyu; Bemis, Karen; Jackson, Darrell; Light, Russ

    2015-04-01

    One intriguing feature of a mid-ocean ridge hydrothermal system is the intimate interconnections among hydrothermal, geological, oceanic, and biological processes. The advent of the NEPTUNE observatory operated by Ocean Networks Canada at the Endeavour Segment, Juan de Fuca Ridge enables scientists to study these interconnections through multidisciplinary, continuous, real-time observations. In this study, we present the time-series observations of a seafloor hydrothermal vent made using the Cabled Observatory Vent Imaging Sonar (COVIS). COVIS is currently connected to the NEPTUNE observatory to monitor the hydrothermal discharge from the Grotto mound on the Endeavour Segment. Since its deployment in 2010, COVIS has recorded a 3-year long dataset of the shape and outflow fluxes of the buoyant plumes above Grotto along with the areal coverage of its diffuse flow discharge. The interpretation of these data in light of contemporaneous observations of ocean currents, venting temperature, and seismicity made using other NEPTUNE observatory instruments reveals significant impacts of ocean currents and geological events on hydrothermal venting. In this study, we summarize these findings in the hope of forming a more complete understanding of the intricate interconnections among oceanic, geological, and hydrothermal processes.

  17. Thin film eddy current impulse deicer

    NASA Technical Reports Server (NTRS)

    Smith, Samuel O.; Zieve, Peter B.

    1990-01-01

    Two new styles of electrical impulse deicers has been developed and tested in NASA's Icing Research Tunnel. With the Eddy Current Repulsion Deicing Boot (EDB), a thin and flexible spiral coil is encapsulated between two thicknesses of elastomer. The coil, made by an industrial printed circuit board manufacturer, is bonded to the aluminum aircraft leading edge. A capacitor bank is discharged through the coil. Induced eddy currents repel the coil from the aluminum aircraft structure and shed accumulated ice. A second configuration, the Eddy Current Repulsion Deicing-Strip (EDS) uses an outer metal erosion strip fastened over the coil. Opposite flowing eddy currents repel the strip and create the impulse deicing force. The outer strip serves as a surface for the collection and shedding of ice and does not require any structural properties. The EDS is suitable for composite aircraft structures. Both systems successfully dispelled over 95 percent of the accumulated ice from airfoils over the range of the FAA icing envelope.

  18. Quantification Approach of Gas Temperate Distribution in Atmospheric Positive DC Glow Discharge Measured by Spectroscopic Imaging

    NASA Astrophysics Data System (ADS)

    Sasamoto, Ryo; Orii, Hideaki; Matsumoto, Takao; Izawa, Yasuji; Nishijima, Kiyoto

    2015-09-01

    In our previous work, a two-dimensional (2D) gas temperature distribution in a positive DC steady-state glow corona was qualitatively measured by spectroscopic imaging. Spectral images of its glow corona were taken using ICCD camera with ultra-narrow band-pass filters, and they were corresponded to the head and tail of a second positive system bands of nitrogen (2PS N2 (0-2)). The qualitative gas temperature was obtained from the emission intensity ratio (I2 Ptail/I2 Phead) between the head and tail of 2PS N2 (0-2). This emission intensity ratio also equals the rotational temperature (TR) , and TR almost equals the gas temperature (TG) in atmospheric pressure. In this work, the qualitative 2D gas temperature distribution was derived from 2D I2 Ptail/I2 Phead plots, and the calibration date of I2 Ptail/I2 Phead for TR was accumulated by investigating the relationship between the spatially average absolute gas temperature (Tav) obtained by single-point spectroscopic measurement and the average value of I2 Ptail/I2 Phead plots. On the basis of the calibration date, a spectroscopically-imaged qualitative 2D I2 Ptail/I2 Phead distribution in a positive DC glow corona was converted to a quantitative 2D image of gas rotational temperature.

  19. Impulse radar studfinder

    DOEpatents

    McEwan, Thomas E.

    1995-01-01

    An impulse radar studfinder propagates electromagnetic pulses and detects reflected pulses from a fixed range. Unmodulated pulses, about 200 ps wide, are emitted. A large number of reflected pulses are sampled and averaged. Background reflections are subtracted. Reflections from wall studs or other hidden objects are detected and displayed using light emitting diodes.

  20. Impulse radar studfinder

    DOEpatents

    McEwan, T.E.

    1995-10-10

    An impulse radar studfinder propagates electromagnetic pulses and detects reflected pulses from a fixed range. Unmodulated pulses, about 200 ps wide, are emitted. A large number of reflected pulses are sampled and averaged. Background reflections are subtracted. Reflections from wall studs or other hidden objects are detected and displayed using light emitting diodes. 9 figs.

  1. Relativistic impulse dynamics.

    PubMed

    Swanson, Stanley M

    2011-08-01

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

  2. [Obsession-impulsion infanticide].

    PubMed

    Gourévitch, Michel

    2006-01-01

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

  3. Irresistible impulse: legal viewpoint.

    PubMed

    Borichansky, L

    1989-01-01

    The legal point of view concerning irresistible impulse as an exemption from criminal liability is discussed. A defendant who pleads that at the time of committing an illegal act he was suffering from a mental disease must prove to the court that his version is the most possible one.

  4. Pancreatitis - discharge

    MedlinePlus

    Chronic pancreatitis - discharge; Pancreatitis - chronic - discharge; Pancreatic insufficiency - discharge; Acute pancreatitis - discharge ... fluids through an intravenous (IV) tube in your vein and nutrition through a feeding tube or IV. ...

  5. Knee arthroscopy - discharge

    MedlinePlus

    ... retinacular release - discharge; Synovectomy - discharge; Patellar debridement - discharge; Meniscus repair - discharge; Lateral release - discharge; Collateral ligament repair - discharge; Knee surgery - ...

  6. A novel technique to monitor thermal discharges using thermal infrared imaging.

    PubMed

    Muthulakshmi, A L; Natesan, Usha; Ferrer, Vincent A; Deepthi, K; Venugopalan, V P; Narasimhan, S V

    2013-09-01

    Coastal temperature is an important indicator of water quality, particularly in regions where delicate ecosystems sensitive to water temperature are present. Remote sensing methods are highly reliable for assessing the thermal dispersion. The plume dispersion from the thermal outfall of the nuclear power plant at Kalpakkam, on the southeast coast of India, was investigated from March to December 2011 using thermal infrared images along with field measurements. The absolute temperature as provided by the thermal infrared (TIR) images is used in the Arc GIS environment for generating a spatial pattern of the plume movement. Good correlation of the temperature measured by the TIR camera with the field data (r(2) = 0.89) make it a reliable method for the thermal monitoring of the power plant effluents. The study portrays that the remote sensing technique provides an effective means of monitoring the thermal distribution pattern in coastal waters. PMID:23839171

  7. A novel technique to monitor thermal discharges using thermal infrared imaging.

    PubMed

    Muthulakshmi, A L; Natesan, Usha; Ferrer, Vincent A; Deepthi, K; Venugopalan, V P; Narasimhan, S V

    2013-09-01

    Coastal temperature is an important indicator of water quality, particularly in regions where delicate ecosystems sensitive to water temperature are present. Remote sensing methods are highly reliable for assessing the thermal dispersion. The plume dispersion from the thermal outfall of the nuclear power plant at Kalpakkam, on the southeast coast of India, was investigated from March to December 2011 using thermal infrared images along with field measurements. The absolute temperature as provided by the thermal infrared (TIR) images is used in the Arc GIS environment for generating a spatial pattern of the plume movement. Good correlation of the temperature measured by the TIR camera with the field data (r(2) = 0.89) make it a reliable method for the thermal monitoring of the power plant effluents. The study portrays that the remote sensing technique provides an effective means of monitoring the thermal distribution pattern in coastal waters.

  8. Full-Scale Schlieren Imaging of Firearms Discharge and Bullets in Flight

    NASA Astrophysics Data System (ADS)

    Grumstrup, Torben; Settles, Gary; Dodson-Dreibelbis, Lori

    2003-11-01

    A lens-and-grid-type schlieren system using a very large grid as a light source, thus having a 2x3m field-of-view, was described at previous APS/DFD meetings. The implementation of high-speed still imaging and cinematography of shock waves with this system has also been described. Schlieren methods and external ballistics have been closely related since Mach and Salcher first photographed shock waves about a bullet in 1887. The reason to revisit the topic here is that a large field of view allows imaging not only of the bullet and muzzle blast, but also of shock wave interactions with the surroundings and with the person firing the gun. Microsecond still images reveal various stages of these phenomena for both transonic and supersonic (pistol and rifle) bullets. High-speed movies at 30,000 frames/s are also presented. Some implications of these results for hearing protection while using firearms, the improvement of gun and ammunition design and safety, and forensic investigations of close-range bullet wounds are discussed.

  9. Stereotactic radiosurgery - discharge

    MedlinePlus

    Gamma knife - discharge; Cyberknife - discharge; Stereotactic radiotherapy - discharge; Fractionated stereotactic radiotherapy- discharge; Cyclotrons- discharge; Linear accelerator- discharge; Lineacs - discharge; Proton beam radiosurgery - discharge

  10. Temporally structured impulse activity in spontaneously discharging somatosensory cortical neurons in the awake cat: recognition and quantitative description of four different patterns of bursts, post-recording GFAP immunohistology and computer reconstruction of the studied cortical surface.

    PubMed

    Miasnikov, A A; Webster, H H; Dykes, R W

    1999-04-01

    We elaborated two methods used in two previous publications [J. Martinson, H.H. Webster, A.A. Myasnikov, R.W. Dykes, Recognition of temporally structured activity in spontaneously discharging neurons in the somatosensory cortex in waking cats, Brain Res. 750 (1997) 129-140 [16]; H.H. Webster, I. Salimi, A.A. Myasnikov, R.W. Dykes. The effects of peripheral deafferentation on spontaneously bursting neurons in the somatosensory cortex of waking cats, Brain Res. 750 (1997) 109-121 [21

  11. Fluvial Discharge Rates of Martian Gullies: Slope Measurements From Stereo HiRISE Images and Numerical Modeling of Sediment Transport

    NASA Astrophysics Data System (ADS)

    Parsons, R. A.; Nimmo, F.; Kreslavsky, M.

    2008-12-01

    Using a stereo pair of HiRISE images of a crater slope incised by fourteen gullies at -37.86 N, 217.92 E we calculate relative elevation changes between pairs of hand-selected points. Using the method of Kreslavsky [1]. The background slope on which the gullies are located has a slope of 22 degrees. Out of the five gullies we analyzed, all show a steadily decreasing slope from an average of 30 ± 4 degrees at the alcove to 16 ± 2 degrees at the apron. These measurements are in agreement with previous gully slope measurements done at MOLA resolution in a different region [2]. The slope beyond the base of the gully aprons is 4±1 degrees. The depth of alcove incision in nine of the gullies is 17±8.5~m. We take advantage of this slope and incision data to determine the evolution of a one-dimensional gully profile over time with a 1D sediment transport model [3]. The shear stress applied to the channel bed by flowing water is τ = ρ g h sinθ where h is the channel depth, g is gravity, and h is the channel depth. The rate of transport is non-linearly related to τ/τrg where the reference stress for a gravel bed is τrg = 0.035 ( (s-1)ρ g Dg ) where s is the ratio of sediment to water density, ρ is 1000~m3, and Dg is the sediment grainsize. The two significant unknowns in applying the theory to Martian gullies are the sediment grainsize and channel depth. We ran simulations for various channel depths and grainsizes to get a range of water discharges and simulation times that result in alcoves 25~m deep. Erosion is rapid due to the high slopes; incision rates decrease with decreasing channel depth and increasing grainsize. For grains 20~cm in diameter and a conservatively low channel depth of 20~cm, alcove incision occurs over a 5~h period, discharging a volume of 8500 m3 of water. These discharges assume a 1~m wide channel and a constant, bank-full discharge over the duration of the simulation. Gullies are spaced about every 500~m along the slope. If liquid water

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

    PubMed

    Grant, Jon E; Chamberlain, Samuel R

    2014-11-01

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

  13. Lung surgery - discharge

    MedlinePlus

    Thoracotomy - discharge; Lung tissue removal - discharge; Pneumonectomy - discharge; Lobectomy - discharge; Lung biopsy - discharge; Thoracoscopy - discharge; Video-assisted thoracoscopic surgery - discharge; VATS - ...

  14. Time-resolved pinhole camera imaging and extreme ultraviolet spectrometry on a hollow cathode discharge in xenon.

    PubMed

    Kieft, E R; van der Mullen, J J A M; Kroesen, G M W; Banine, V

    2003-11-01

    A pinhole camera, an extreme ultraviolet (EUV) spectrometer, a fast gatable multichannel plate EUV detector, and a digital camera have been installed on the ASML EUV laboratory setup to perform time-resolved pinhole imaging and EUV spectroscopy on a copy of the Philips EUV hollow cathode discharge plasma source. The main properties of the setup have been characterized. Time-resolved measurements within the plasma pulse in the EUV have been performed on this source. Specific features of the plasma, such as a ring shape in the initiation phase and a propagating sphere during the pinch phase, have either been discovered or confirmed experimentally. Relative populations of various ionization stages in the pinch plasma have been estimated on the basis of line intensities and calculated transition probabilities. The changes in relative line intensities of a single ionization stage can be explained by a combination of temperature and excitation/deexcitation balance effects. Experiments with argon dilution on a newer version of the source show considerable effect on the shape of the xenon EUV spectrum.

  15. Kidney stones - lithotripsy - discharge

    MedlinePlus

    Extracorporeal shock wave lithotripsy - discharge; Shock wave lithotripsy - discharge; Laser lithotripsy - discharge; Percutaneous lithotripsy - discharge; Endoscopic lithotripsy - discharge; ESWL - ...

  16. Radical prostatectomy - discharge

    MedlinePlus

    ... prostatectomy - discharge; Laparoscopic radical prostatectomy - discharge; LRP - discharge; Robotic-assisted laparoscopic prostatectomy - discharge ; RALP - discharge; Pelvic lymphadenectomy - ...

  17. Intelligent detection of impulse noise using multilayer neural network with multi-valued neurons

    NASA Astrophysics Data System (ADS)

    Aizenberg, Igor; Wallace, Glen

    2012-03-01

    In this paper, we solve the impulse noise detection problem using an intelligent approach. We use a multilayer neural network based on multi-valued neurons (MLMVN) as an intelligent impulse noise detector. MLMVN was already used for point spread function identification and intelligent edge enhancement. So it is very attractive to apply it for solving another image processing problem. The main result, which is presented in the paper, is the proven ability of MLMVN to detect impulse noise on different images after a learning session with the data taken just from a single noisy image. Hence MLMVN can be used as a robust impulse detector. It is especially efficient for salt and pepper noise detection and outperforms all competitive techniques. It also shows comparable results in detection of random impulse noise. Moreover, for random impulse noise detection, MLMVN with the output neuron with a periodic activation function is used for the first time.

  18. Neural correlates of choice behavior related to impulsivity and venturesomeness.

    PubMed

    Hinvest, Neal S; Elliott, R; McKie, S; Anderson, Ian M

    2011-07-01

    Impulsivity has been associated with several psychiatric disorders including drug addiction and gambling. Impulsive subjects typically have a preference for short-term over long-term rewards and make risky choices. This study used functional magnetic resonance imaging (fMRI) to investigate the neural correlates of self-rated impulsivity and venturesomeness during tasks involving delayed and risky choice. A broader sampling approach was taken by recruiting participants with behaviors that have been linked to impulsivity (gambling N=15, and recreational drug use N=10) and those without these behaviors (N=9). Selection between delayed or probabilistic rewards was associated with activation in fronto-parietal regions in line with previous research. When selecting between delayed rewards, activity within the pregenual anterior cingulate cortex and ventrolateral prefrontal cortex correlated positively with impulsivity scores while activity within the orbitofrontal cortex, subgenual anterior cingulate cortex and caudate correlated positively with venturesomeness scores. Selection between probabilistic rewards revealed no correlation between scores and regional activations. The results from this study provide targets for future research investigating the neural substrates of impulsivity. They also provide targets for the further investigation into the pathophysiology of addiction and impulse-control disorders.

  19. Comparison of acoustic radiation force impulse imaging and transient elastography for non-invasive assessment of liver fibrosis in patients with chronic hepatitis B.

    PubMed

    Zhang, Dakun; Chen, Min; Wang, Ruifang; Liu, Yang; Zhang, Dedong; Liu, Liping; Zhou, Guangde

    2015-01-01

    The aims of this study were to compare the performance of acoustic radiation force impulse (ARFI) elastography and transient elastography (TE) in the assessment of liver fibrosis in patients with chronic hepatitis B and to evaluate the impact of elevated alanine transaminase levels on liver stiffness assessment using ARFI elastography. One hundred eighty consecutive patients with chronic hepatitis B were enrolled in this study and evaluated with respect to histologic and biochemical features. All patients underwent ARFI elastography and TE. ARFI elastography and TE correlated significantly with histologically assessed fibrosis (r = 0.599, p < 0.001, for ARFI elastography; r = 0.628, p < 0.001, for TE) and necro-inflammatory activity (r = 0.591, p < 0.001, for ARFI elastography; r = 0.616, p < 0.001, for TE). Areas under the receiver operating characteristic curves for ARFI elastography and TE were 0.764 and 0.813 (p = 0.302, ≥stage 2), 0.852 and 0.852 (p = 1.000, ≥stage 3) and 0.825 and 0.799 (p = 0.655, S = 4), respectively. The optimum cutoff values for ARFI elastography were 1.63 m/s for stage ≥2, 1.74 m/s for stage ≥3 and 2.00 m/s for stage 4 in patients for whom alanine transaminase levels were evaluated. The cutoff values decreased to 1.24 m/s for ≥ stage 2, 1.32 m/s for ≥ stage 3 and 1.41 m/s for stage 4 in patients with normal alanine transaminase levels. ARFI elastography may be a reliable method for diagnosing the stage of liver fibrosis with diagnostic performance similar to that of TE in patients with chronic hepatitis B. In addition, liver stiffness values obtained with ARFI elastography, like those obtained with TE, may be influenced by alanine transaminase levels.

  20. Teaching about Impulse and Momentum

    ERIC Educational Resources Information Center

    Franklin, Bill

    2004-01-01

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

  1. Cigarette Cravings, Impulsivity, and the Brain

    PubMed Central

    Potvin, Stéphane; Tikàsz, Andràs; Dinh-Williams, Laurence Lê-Anh; Bourque, Josiane; Mendrek, Adrianna

    2015-01-01

    Craving is a core feature of tobacco use disorder as well as a significant predictor of smoking relapse. Studies have shown that appetitive smoking-related stimuli (e.g., someone smoking) trigger significant cravings in smokers impede their self-control capacities and promote drug seeking behavior. In this review, we begin by an overview of functional magnetic resonance imaging (fMRI) studies investigating the neural correlates of smokers to appetitive smoking cues. The literature reveals a complex and vastly distributed neuronal network underlying smokers’ craving response that recruits regions involved in self-referential processing, planning/regulatory processes, emotional responding, attentional biases, and automatic conducts. We then selectively review important factors contributing to the heterogeneity of results that significantly limit the implications of these findings, namely between- (abstinence, smoking expectancies, and self-regulation) and within-studies factors (severity of smoking dependence, sex-differences, motivation to quit, and genetic factors). Remarkably, we found that little to no attention has been devoted to examine the influence of personality traits on the neural correlates of cigarette cravings in fMRI studies. Impulsivity has been linked with craving and relapse in substance and tobacco use, which prompted our research team to examine the influence of impulsivity on cigarette cravings in an fMRI study. We found that the influence of impulsivity on cigarette cravings was mediated by fronto-cingulate mechanisms. Given the high prevalence of cigarette smoking in several psychiatric disorders that are characterized by significant levels of impulsivity, we conclude by identifying psychiatric patients as a target population whose tobacco-smoking habits deserve further behavioral and neuro-imaging investigation. PMID:26441686

  2. Impulse control in pigeons.

    PubMed

    Ainslie, G W

    1974-05-01

    Pigeons were given a small, immediate food reinforcement for pecking a key, and a larger, delayed reinforcement for not pecking this key. Most subjects pecked the key on more than 95% of trials. However, when pecking a differently colored key at an earlier time prevented this option from becoming available, three of 10 subjects consistently pecked it, thereby forcing themselves to wait for the larger reward. They did not peck the earlier key when it did not prevent this option. This is an experimental example of psychological impulse and a learnable device to control it. Although only a minority of the subjects learned it, the fact that such learning is possible at all argues for a theory of delayed reward that can predict change of preference as a function of elapsing time.

  3. Right ventromedial prefrontal cortex: a neuroanatomical correlate of impulse control in boys

    PubMed Central

    Bechara, Antoine; Tranel, Daniel; Anderson, Steve W.; Richman, Lynn; Nopoulos, Peg

    2009-01-01

    Emerging data on the neural mechanisms of impulse control highlight brain regions involved in emotion and decision making, including the ventromedial prefrontal cortex (vmPFC), anterior cingulate cortex (ACC) and amygdala. Variation in the development of these regions may influence one's propensity for impulsivity and, by extension, one's vulnerability to disorders involving low impulse control (e.g. substance abuse). Here we test the hypothesis that lower impulse control is associated with structural differences in these regions, particularly on the right side, in 61 normal healthy boys aged 7–17. We assessed parent- and teacher-reported behavioral ratings of impulse control (motor impulsivity and non-planning behavior) in relation to vmPFC, ACC and amygdala volume, measured using structural magnetic resonance imaging and FreeSurfer. A regression analysis showed that the right vmPFC was a significant predictor of impulse control ratings. Follow-up tests showed (i) a significant correlation between low impulse control and decreased right vmPFC volume, especially the medial sector of the vmPFC and (ii) significantly lower right vmPFC volume in a subgroup of 20 impulsive boys relative to 20 non-impulsive boys. These results are consistent with the notion that right vmPFC provides a neuroanatomical correlate of the normal variance in impulse control observed in boys. PMID:19015086

  4. Qualifying an impulse digitizer for measurements in HV impulse tests

    SciTech Connect

    McComb, T.R. ); Kuffel, J. . Research Div.); Malewski, R. ); Schon, K. )

    1990-07-01

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

  5. 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.

  6. On reactive high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gudmundsson, J. T.

    2016-01-01

    High power impulse magnetron sputtering (HiPIMS) is an ionized physical vapor deposition (IPVD) technique that is particularly promising for reactive sputtering applications. However, there are few issues that have to be resolved before the full potential of this technique can be realized. Here we give an overview of the key experimental findings for the reactive HiPIMS discharge. An increase in the discharge current is commonly observed with increased partial pressure of the reactive gas or decreased repetition pulse frequency. There are somewhat conflicting claims regarding the hysteresis effect in the reactive HiPIMS discharge as some report reduction or elimination of the hysteresis effect while others claim a feedback control is essential. The ion energy distribution of the metal ion and the atomic ion of the reactive gas are similar and extend to very high energies while the ion energy distribution of the working gas and the molecular ion of the reactive gas are similar and are much less energetic.

  7. Variable Specific Impulse Magnetoplasma Rocket Engine

    NASA Technical Reports Server (NTRS)

    Chang-Diaz, Franklin R. (Inventor)

    2002-01-01

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

  8. Vaginal Discharge

    MedlinePlus

    ... also be on the lookout for symptoms of yeast infections, bacterial vaginosis and trichomoniasis, 3 infections that ... cause changes in your vaginal discharge. Signs of yeast infections White, cottage cheese-like discharge Swelling and ...

  9. Non-destructive monitoring of charge-discharge cycles on lithium ion batteries using ⁷Li stray-field imaging.

    PubMed

    Tang, Joel A; Dugar, Sneha; Zhong, Guiming; Dalal, Naresh S; Zheng, Jim P; Yang, Yong; Fu, Riqiang

    2013-01-01

    Magnetic resonance imaging provides a noninvasive method for in situ monitoring of electrochemical processes involved in charge/discharge cycling of batteries. Determining how the electrochemical processes become irreversible, ultimately resulting in degraded battery performance, will aid in developing new battery materials and designing better batteries. Here we introduce the use of an alternative in situ diagnostic tool to monitor the electrochemical processes. Utilizing a very large field-gradient in the fringe field of a magnet, stray-field-imaging (STRAFI) technique significantly improves the image resolution. These STRAFI images enable the real time monitoring of the electrodes at a micron level. It is demonstrated by two prototype half-cells, graphite∥Li and LiFePO₄∥Li, that the high-resolution (7)Li STRAFI profiles allow one to visualize in situ Li-ions transfer between the electrodes during charge/discharge cyclings as well as the formation and changes of irreversible microstructures of the Li components, and particularly reveal a non-uniform Li-ion distribution in the graphite.

  10. Comparative study of thermal infrared imaging and fibre-optic distributed temperature sensing for detecting lacustrine groundwater discharge: a mesocosm experiment

    NASA Astrophysics Data System (ADS)

    Marruedo Arricibita, Amaia I.; Lewandowski, Jörg; Krause, Stefan; Hannah, David M.

    2016-04-01

    Detecting lacustrine groundwater discharge (LGD) still remains a challenge. The buoyancy of groundwater during winter and early spring can be used for identification of groundwater up-welling related hotspots on surface water by TIR imaging (TIR). TIR has been successfully used to image and fast screen relatively large surface areas of coastal zones, lakes, reservoirs and large rivers for groundwater contributions. Still, quantitative interpretations of groundwater fluxes are hampered by the lack of understanding how the groundwater up-welling signal propagates from the sediment-water interface through the water column to the water-air interface and what perturbations and signal losses occur along this pathway. In the present study, groundwater discharge to a surface water body was simulated in a mesocosm experiment. Under winter conditions water of 14° C to 16°C was discharged at the bottom of a 10x2.8 m mesocosm where surface water varied from 4°C -7.4°C. Four layers (20, 40, 60 and 80 cm above the sediment) of the 81 cm deep mesocosm were equipped with fibre-optic distributed temperature sensing (FO-DTS) for tracing thermal patterns in the mesocosm and TIR imaging was deployed to monitor temperature pattern at the water surface in order to: (1) analyze the propagation of the temperature signal through the water column by FO-DTS and (2) characterize the spatial distribution of groundwater upwelling at the pond surface by FO-DTS and TIR. Different LGD rates were simulated in order to establish the minimum rate of GW upwelling that can be reliably detected at the water surface by TIR imaging. The experiments also allow us to benchmark scale dependencies and adequacy of both methods, FO-DTS and TIR. They also reveal that weather conditions can have important impacts on the detection of LGD at surface water-atmosphere interfaces at larger scales.

  11. Reflection impulsivity in binge drinking: behavioural and volumetric correlates.

    PubMed

    Banca, Paula; Lange, Iris; Worbe, Yulia; Howell, Nicholas A; Irvine, Michael; Harrison, Neil A; Moutoussis, Michael; Voon, Valerie

    2016-03-01

    The degree to which an individual accumulates evidence prior to making a decision, also known as reflection impulsivity, can be affected in psychiatric disorders. Here, we study decisional impulsivity in binge drinkers, a group at elevated risk for developing alcohol use disorders, comparing two tasks assessing reflection impulsivity and a delay discounting task, hypothesizing impairments in both subtypes of impulsivity. We also assess volumetric correlates of reflection impulsivity focusing on regions previously implicated in functional magnetic resonance imaging studies. Sixty binge drinkers and healthy volunteers were tested using two different information-gathering paradigms: the beads task and the Information Sampling Task (IST). The beads task was analysed using a behavioural approach and a Bayesian model of decision making. Delay discounting was assessed using the Monetary Choice Questionnaire. Regression analyses of primary outcomes were conducted with voxel-based morphometry analyses. Binge drinkers sought less evidence prior to decision in the beads task compared with healthy volunteers in both the behavioural and computational modelling analysis. There were no group differences in the IST or delay discounting task. Greater impulsivity as indexed by lower evidence accumulation in the beads task was associated with smaller dorsolateral prefrontal cortex and inferior parietal volumes. In contrast, greater impulsivity as indexed by lower evidence accumulation in the IST was associated with greater dorsal cingulate and precuneus volumes. Binge drinking is characterized by impaired reflection impulsivity suggesting a deficit in deciding on the basis of future outcomes that are more difficult to represent. These findings emphasize the role of possible therapeutic interventions targeting decision-making deficits.

  12. Reflection impulsivity in binge drinking: behavioural and volumetric correlates

    PubMed Central

    Banca, Paula; Lange, Iris; Worbe, Yulia; Howell, Nicholas A.; Irvine, Michael; Harrison, Neil A.; Moutoussis, Michael

    2015-01-01

    Abstract The degree to which an individual accumulates evidence prior to making a decision, also known as reflection impulsivity, can be affected in psychiatric disorders. Here, we study decisional impulsivity in binge drinkers, a group at elevated risk for developing alcohol use disorders, comparing two tasks assessing reflection impulsivity and a delay discounting task, hypothesizing impairments in both subtypes of impulsivity. We also assess volumetric correlates of reflection impulsivity focusing on regions previously implicated in functional magnetic resonance imaging studies. Sixty binge drinkers and healthy volunteers were tested using two different information‐gathering paradigms: the beads task and the Information Sampling Task (IST). The beads task was analysed using a behavioural approach and a Bayesian model of decision making. Delay discounting was assessed using the Monetary Choice Questionnaire. Regression analyses of primary outcomes were conducted with voxel‐based morphometry analyses. Binge drinkers sought less evidence prior to decision in the beads task compared with healthy volunteers in both the behavioural and computational modelling analysis. There were no group differences in the IST or delay discounting task. Greater impulsivity as indexed by lower evidence accumulation in the beads task was associated with smaller dorsolateral prefrontal cortex and inferior parietal volumes. In contrast, greater impulsivity as indexed by lower evidence accumulation in the IST was associated with greater dorsal cingulate and precuneus volumes. Binge drinking is characterized by impaired reflection impulsivity suggesting a deficit in deciding on the basis of future outcomes that are more difficult to represent. These findings emphasize the role of possible therapeutic interventions targeting decision‐making deficits. PMID:25678093

  13. Impulsive and Compulsive Behaviours in Parkinson's disease

    PubMed Central

    Averbeck, BB; O’Sullivan, SS; Djamshidian, A

    2014-01-01

    Impulsive compulsive behaviours (ICBs) in Parkinson’s disease (PD) are a common and devastating side effect of dopamine replacement therapy. In this review we describe the phenomenology, prevalence and risk factors of these patients. Results of behavioural studies assessing the neuropsychological profile emphasize that the ICBs, which are behavioural addictions, are not hedonically motivated. Rather, other factors such as the inability to cope with uncertainty may be triggering ICBs. New insights from functional imaging studies, strengthening the incentive salience hypothesis are discussed and therapeutic guidelines for the management of ICBs in PD are given. PMID:24313567

  14. Laboratory behavioral measures of impulsivity.

    PubMed

    Dougherty, Donald M; Mathias, Charles W; Marsh, Dawn M; Jagar, Ashley A

    2005-02-01

    Previous research and theory have conceptualized impulsivity as a multifaceted construct that requires multiple modes of measurement for accurate assessment. This article describes a software package that includes four paradigms for measuring multiple and unique aspects of impulsivity. Specifically, four tasks are described: (1) the two choice impulsivity paradigm, (2) the single key impulsivity paradigm, (3) the GoStop impulsivity paradigm, and (4) the time paradigm. These tasks measure processes related to the capacity to tolerate delay for reward, to inhibit an already initiated response, and to estimate the passage of time. These processes have been found to be important to the understanding of impulsive behaviors. The programs are flexible and allow the experimenter to manipulate a number of parameters related to delay-reward contingencies, timing, performance feedback/payment, and data output variables. Manipulation of these parameters makes the paradigms scalable to a wide range of ability levels and appropriate for samples ranging from children to adults. The four paradigms in this software package are available at no cost and can be obtained by contacting the corresponding author.

  15. Impulsivity, Risk Taking, and Timing

    PubMed Central

    Baumann, Ana A.; Odum, Amy. L.

    2012-01-01

    This study examined the relations among measures of impulsivity and timing. Impulsivity was assessed using delay and probability discounting, and self-report impulsivity (as measured by the Barratt Impulsiveness Scale; BIS-11). Timing was assessed using temporal perception as measured on a temporal bisection task and time perspective (as measured by the Zimbardo Time Perspective Inventory). One hundred and forty three college students completed these measures in a computer laboratory. The degree of delay discounting was positively correlated with the mean and range of the temporal bisection procedure. The degree of delay and probability discounting were also positively correlated. Self-reported Motor impulsiveness on the BIS-11 was positively correlated with Present Hedonism and negatively correlated with Future orientation on the ZTPI. Self-reported Non-Planning on the BIS-11 was positively correlated with Fatalism on the ZTPI. These results show that people who overestimate the passage of time (perceive time as passing more quickly) hold less value in delayed rewards. They also confirm previous results regarding the relation between delay and probability discounting, as well as highlight similarities in self-report measures of impulsivity and time perspective. PMID:22542458

  16. Impulsivity, risk taking, and timing.

    PubMed

    Baumann, Ana A; Odum, Amy L

    2012-07-01

    This study examined the relations among measures of impulsivity and timing. Impulsivity was assessed using delay and probability discounting, and self-report impulsivity (as measured by the Barratt Impulsiveness Scale; BIS-11). Timing was assessed using temporal perception as measured on a temporal bisection task and time perspective (as measured by the Zimbardo Time Perspective Inventory). One hundred and forty three college students completed these measures in a computer laboratory. The degree of delay discounting was positively correlated with the mean and range of the temporal bisection procedure. The degree of delay and probability discounting were also positively correlated. Self-reported motor impulsiveness on the BIS-11 was positively correlated with present hedonism and negatively correlated with future orientation on the ZTPI. Self-reported non-planning on the BIS-11 was positively correlated with fatalism on the ZTPI. These results show that people who overestimate the passage of time (perceive time as passing more quickly) hold less value in delayed rewards. They also confirm previous results regarding the relation between delay and probability discounting, as well as highlight similarities in self-report measures of impulsivity and time perspective.

  17. Open-loop dereverberation of multichannel room impulse responses

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

    We are developing the audio display for a CAVE-type virtual reality theater, a 3-m cube with displays covering all six rigid faces. The user's headgear continuously reports ear positions so headphones would be possible, but we nevertheless prefer loudspeakers because this enhances the sense of total immersion. Because sounds produced at the loudspeakers are distorted by the room impulse responses, we therefore face the problem of controlling the sound at the listener's two ears. Our proposed solution consists of open-loop acoustic point control, i.e., dereverberation. The room impulse responses from each loudspeaker to each ear of the listener are inverted using multichannel inversion methods, to create exactly the desired sound field at the listener's ears. Because the actual room impulse responses cannot be measured in real time (as the listener walks around), instead the impulse responses simulated by the image-source method is used. A new evaluation criterion is proposed to quantitatively evaluate both the simulation and the open-loop dereverberation. The actual impulse responses used for this evaluation are measured with a starter pistol, since this best approximates the point source assumed by the image-source method.

  18. Solar flare impulsive phase emission observed with SDO/EVE

    SciTech Connect

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

    2013-12-10

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

  19. Bone marrow transplant - discharge

    MedlinePlus

    Transplant - bone marrow - discharge; Stem cell transplant - discharge; Hematopoietic stem cell transplant - discharge; Reduced intensity; Non-myeloablative transplant - discharge; Mini transplant - discharge; Allogenic bone marrow transplant - ...

  20. Pediatric heart surgery - discharge

    MedlinePlus

    Congenital heart surgery - discharge; Patent ductus arteriosus ligation - discharge; Hypoplastic left heart repair - discharge; Tetralogy of Fallot repair - discharge; Coarctation of the aorta repair - discharge; ...

  1. Deep vein thrombosis - discharge

    MedlinePlus

    DVT - discharge; Blood clot in the legs - discharge; Thromboembolism - discharge; Venous thromboembolism - deep vein thrombosis; Post-phlebitic syndrome - discharge; Post-thrombotic syndrome - discharge

  2. Dynamic Initiator Experiments using IMPULSE (Impact system for Ultrafast Synchrotron Experiments) at the Advanced Photon Source

    NASA Astrophysics Data System (ADS)

    Sanchez, Nathaniel; Jensen, Brian; Ramos, Kyle; Iverson, Adam; Martinez, Michael; Liechty, Gary; Fezzaa, Kamel; Clarke, Steven

    2015-06-01

    We have successfully imaged, for the first time, the operation of copper slapper initiators that are used to initiate high explosive detonators. These data will aid in model development and calibration in order to provide a robust predictive capability and as a design tool in future applications. The initiation system consists of a copper bridge fixed to a parylene flyer. The copper bridge functions when a capacitor is discharged causing current to flow through the narrow bridge. As this happens, a plasma forms due to the high current densities and ohmic heating, which launches the parylene flyer that impacts a high explosive pellet producing detonation. Unlike traditional measurements, x-ray phase contrast imaging can see ``inside'' the process providing unique information with nanosecond time resolution and micrometer spatial resolution. The team performed experiments on the IMPULSE system at the Advanced Photon Source to obtain high resolution, in situ images of this process in real-time. From these images, researchers can examine the formation of the plasma instabilities and their interaction with the flyer, determine the flyer velocity, and obtain crucial information on the spatial distribution of mass and density gradients in the plasma and flyer.

  3. Research on water discharge characteristics of PEM fuel cells by using neutron imaging technology at the NRF, HANARO.

    PubMed

    Kim, TaeJoo; Sim, CheulMuu; Kim, MooHwan

    2008-05-01

    An investigation into the water discharge characteristics of proton exchange membrane (PEM) fuel cells is carried out by using a feasibility test apparatus and the Neutron Radiography Facility (NRF) at HANARO. The feasibility test apparatus was composed of a distilled water supply line, a compressed air supply line, heating systems, and single PEM fuel cells, which were a 1-parallel serpentine type with a 100 cm(2) active area. Three kinds of methods were used: compressed air supply-only; heating-only; and a combination of the methods of a compressed air supply and heating, respectively. The resultant water discharge characteristics are different according to the applied methods. The compressed air supply only is suitable for removing the water at a flow field and a heating only is suitable for water at the MEA. Therefore, in order to remove all the water at PEM fuel cells, the combination method is needed at the moment.

  4. Non-uniform temperature distribution in Li-ion batteries during discharge - A combined thermal imaging, X-ray micro-tomography and electrochemical impedance approach

    NASA Astrophysics Data System (ADS)

    Robinson, James B.; Darr, Jawwad A.; Eastwood, David S.; Hinds, Gareth; Lee, Peter D.; Shearing, Paul R.; Taiwo, Oluwadamilola O.; Brett, Dan J. L.

    2014-04-01

    Thermal runaway is a major cause of failure in Li-ion batteries (LIBs), and of particular concern for high energy density transport applications, where safety concerns have hampered commercialisation. A clear understanding of electro-thermal properties and how these relate to structure and operation is vital to improving thermal management of LIBs. Here a combined thermal imaging, X-ray tomography and electrochemical impedance spectroscopy (EIS) approach was applied to commercially available 18650 cells to study their thermal characteristics. Thermal imaging was used to characterise heterogeneous temperature distributions during discharge above 0.75C; the complementary information provided by 3D X-ray tomography was utilised to evaluate the internal structure of the battery and identify the regions causing heating, specifically the components of the battery cap.

  5. Gated pinhole camera imaging of the high-energy ions emitted by a discharge produced Sn plasma for extreme ultraviolet generation

    SciTech Connect

    Gielissen, K.; Mullen, J. J. A. M. van den; Sidelnikov, Y.; Glushkov, D.; Banine, V.; Soer, W. A.

    2009-10-15

    The origin and nature of the high-energy ions emitted by a discharge produced plasma source are studied using gated pinhole camera imaging. Time-of-flight analysis in combination with Faraday cup measurements enables characterization of the high-velocity component of the ionic debris. The use of an optional magnetic field allows mass-to-charge analysis of the first part of the Faraday cup signal. It is shown that this consists mainly of oxygen ions emitted from a region near the cathode. Time-resolved images of Sn ions with a kinetic energy of 45 keV visualize the regions in between the electrodes where the high-energy ion generation takes place.

  6. 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.

  7. Neural mechanisms of impulse control in sexually risky adolescents

    PubMed Central

    Goldenberg, Diane; Telzer, Eva H.; Lieberman, Matthew D.; Fuligni, Andrew; Galván, Adriana

    2014-01-01

    The consequences of risky sexual behavior are of public concern. Adolescents contribute disproportionately to negative consequences of risky sexual behavior. However, no research has examined the neural correlates of impulse control and real-world engagement in risky sexual behavior in this population. The aim of the present study was to examine this question. Twenty sexually active adolescents performed an impulse control task during a functional magnetic resonance imaging (fMRI) scan and risky sexual behaviors were assessed through self-report. Sexual riskiness ratings were negatively associated with activation in the prefrontal cortex during response inhibition. These results suggest that diminished engagement of impulse control circuitry may contribute to sexual riskiness in adolescents. PMID:23835204

  8. Robust Lee local statistic filter for removal of mixed multiplicative and impulse noise

    NASA Astrophysics Data System (ADS)

    Ponomarenko, Nikolay N.; Lukin, Vladimir V.; Egiazarian, Karen O.; Astola, Jaakko T.

    2004-05-01

    A robust version of Lee local statistic filter able to effectively suppress the mixed multiplicative and impulse noise in images is proposed. The performance of the proposed modification is studied for a set of test images, several values of multiplicative noise variance, Gaussian and Rayleigh probability density functions of speckle, and different characteris-tics of impulse noise. The advantages of the designed filter in comparison to the conventional Lee local statistic filter and some other filters able to cope with mixed multiplicative+impulse noise are demonstrated.

  9. Commentary on Hyperkinetic Impulse Disorder

    ERIC Educational Resources Information Center

    Barkley, Russell A.

    2011-01-01

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

  10. Demonstrating Sound Impulses in Pipes.

    ERIC Educational Resources Information Center

    Raymer, M. G.; Micklavzina, Stan

    1995-01-01

    Describes a simple, direct method to demonstrate the effects of the boundary conditions on sound impulse reflections in pipes. A graphical display of the results can be made using a pipe, cork, small hammer, microphone, and fast recording electronics. Explains the principles involved. (LZ)

  11. Prostate resection - minimally invasive - discharge

    MedlinePlus

    Laser prostatectomy - discharge; Transurethral needle ablation - discharge; TUNA - discharge; Transurethral incision - discharge; TUIP - discharge; Holmium laser enucleation of the prostate - discharge; HoLep - discharge; Interstitial laser ...

  12. [Nipple discharge].

    PubMed

    Deodato, G; Consoli, A; Riggi, M; Longo, G; Finocchiaro, G B

    1981-02-01

    The Authors examine the various types of breast discharge concentrating in particular on the secretions due to inherent pathology. After having studied origin, they concentrate on the diagnostic significance and the limits of exfoliative cytology and contrast mammography. The Authors conclude by presenting an original protocol of treatment of the afflicted breast illustrating in addition, the various surgical techniques proposed for the cure of the sicknesses of intramammary origin that cause abnormal discharge. PMID:7261200

  13. Characteristics of Impulsive Suicide Attempts and Attempters.

    ERIC Educational Resources Information Center

    Simon, Thomas R.; Swann, Alan C.; Powell, Kenneth E.; Potter, Lloyd B.; Kresnow, Marcie-jo; O'Carroll, Patrick W.

    2002-01-01

    Examined impulsive suicide attempts within a population-based, case-control study of nearly lethal suicide attempts among adolescents and young adults. Impulsive attempts were more likely among those who had been in a physical fight and less likely among those who were depressed. Findings suggest inadequate control of aggressive impulses as a…

  14. Adolescent Impulsivity: Findings from a Community Sample

    ERIC Educational Resources Information Center

    d'Acremont, Mathieu; Van der Linden, Martial

    2005-01-01

    Impulsivity is central to several psychopathological states in adolescence. However, there is little consensus concerning the definition of impulsivity and its core dimensions. In response to this lack of consensus, Whiteside and Lynam (2001, "Pers. Individ. Differ." 30, 669-689) have developed the UPPS Impulsive Behavior Scale, which is able to…

  15. An impulse radar array for detecting land mines

    SciTech Connect

    Gavel, D.T.; Mast, J.E.; Warhus, J.; Azevedo, S.G.

    1995-04-03

    The Lawrence Livermore National Laboratory has developed radar and imaging technologies with potential application in demining efforts. A patented wideband (impulse) radar that is very compact, very low cost, and very low power, has been demonstrated in test fields to be able to detect and image nonmetallic land mines buried in 2-10 cm of soil. The scheme takes advantage of the very short radar impulses and the ability to form a large synthetic aperture with many small individual units, to generate high resolution 2-D or 3-D tomographic images of the mine and surrounding ground. Radar range calculations predict that a vehicle-mounted or man-carried system is quite feasible using this technology. This paper presents the results of field tests using a prototype unit and describes practical mine detection system concepts. Predicted capabilities in terms of stand-off range and radiated power requirements are discussed.

  16. Heart attack - discharge

    MedlinePlus

    Myocardial infarction - discharge; MI - discharge; Coronary event - discharge; Infarct - discharge ... patients with unstable angina/non-ST-Elevation myocardial infarction: a report of the American College of Cardiology/ ...

  17. 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

  18. Impulse-based methods for fluid flow

    SciTech Connect

    Cortez, R.

    1995-05-01

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

  19. SAR impulse response with residual chirps.

    SciTech Connect

    Doerry, Armin Walter

    2009-06-01

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

  20. Emotion Regulation and Impulsivity in Young Adults

    PubMed Central

    Schreiber, Liana R.N.; Grant, Jon E.; Odlaug, Brian L.

    2012-01-01

    Past research has linked both emotion regulation and impulsivity with the development and maintenance of addictions. However, no research has investigated the relationship between emotion regulation and impulsivity within young adults. In the present study, we analyzed 194 young adults (27.8% female; 21.3 ± 3.32 years old; 91.8% single; 85.1% Caucasian), grouping them as low, average, or high emotionally dysregulated, and compared self-reported impulsivity, impulsive behaviors (such as alcohol and substance use and gambling) and cognitive impulsivity. We hypothesized that those with high levels of emotion dysregulation would score higher on self-reported and cognitive impulsivity, and report more impulsive behaviors. Analysis indicated that compared to low, the high emotion dysregulation group scored significantly higher on two self-report measures of impulsivity, harm avoidance, and cognitive reasoning. No significant differences were found between groups in impulsive behaviors and cognitive impulsivity. Overall, this study highlights the relationship between emotion dysregulation and impulsivity, suggesting that emotion regulation may be an important factor to consider when assessing individuals at a higher risk for developing an addiction. PMID:22385661

  1. Neurophysiological markers of multiple facets of impulsivity.

    PubMed

    Neal, Lauren B; Gable, Philip A

    2016-03-01

    Human behavior is influenced by three core personality systems: approach, avoidance, and supervisory control. The supervisory control system is inversely related to impulsivity. Although past research has related some aspects of impulsivity to frontal hemispheric asymmetry, impulsivity as a multi-faceted construct has not been studied in relation with frontal asymmetry. In addition, past work has potentially confounded impulsivity with approach-motivation. In the current study, greater relative left frontal activity was related to multiple facets of impulsivity: negative urgency, lack of premeditation, lack of perseverance, and positive urgency. Regressing both positive and negative urgency on frontal asymmetry revealed that approach-related positive urgency related to greater left frontal activity, but withdrawal-related negative urgency marginally related to greater right frontal activity. These results suggest that impulsivity, independent of affective valence, relates to greater left frontal activity. When controlling for trait approach motivation, the relationship between impulsivity and left frontal activity is unchanged.

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

    PubMed

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

    2013-06-01

    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.

  3. 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

  4. Interactions between surface discharges induced by volume discharges in a dielectric barrier discharge system

    SciTech Connect

    Gao, Yenan; Dong, Lifang Zhao, Longhu; Wang, Yongjie; Pan, Yuyang; Li, Ben

    2014-10-15

    The interaction between micro-discharges involved in surface discharges (SDs) is studied in dielectric barrier discharge system. Instantaneous images taken by high speed cameras show that the SDs are induced by volume discharges (VDs). They cannot cross the midperpendicular of two neighbouring volume charges at low voltage while they stretch along it at high voltage, indicating that there is interaction between SDs. The differences of plasma parameters between SD and VD are studied by optical emission spectroscopy. The simulation of the electric fields of the wall charges accumulated by VD further confirms the existence of the interaction.

  5. What does See the Impulse Acoustic Microscopy inside Nanocomposites?

    NASA Astrophysics Data System (ADS)

    Levin, V. M.; Petronyuk, Y. S.; Morokov, E. S.; Celzard, A.; Bellucci, S.; Kuzhir, P. P.

    The paper presents results of studying bulk microstructure in carbon nanocomposites by impulse acoustic microscopy technique. Nanocomposite materials are in the focus of interest because of their outstanding properties in minimal nanofiller content. Large surface area and high superficial activity cause strong interaction between nanoparticles that can result in formation of fractal conglomerates. This paper involves results of the first direct observation of nanoparticle conglomerates inside the bulk of epoxy-carbon nanocomposites. Diverse types of carbon nanofiller have been under investigation. The impulse acoustic microscope SIAM-1 (Acoustic Microscopy Lab, IBCP RAS) has been employed for 3D imaging bulk microstructure and measuring elastic properties of the nanocomposite specimens. The range of 50-200 MHz allows observing microstructure inside the entire specimen bulk. Acoustic images are obtained in the ultramicroscopic regime; they are formed by the Rayleigh type scattered radiation. It has been found the high-resolution acoustic vision (impulse acoustic microscopy) is an efficient technique to observe mesostructure formed by fractal cluster inside nanocomposites. The clusterization takes its utmost form in nanocomposites with graphite nanoplatelets as nanofiller. The nanoparticles agglomerate into micron-sized conglomerates distributed randomly over the material. Mesostructure in nanocomposites filled with carbon nanotubes is alternation of regions with diverse density of nanotube packing. Regions with alternative density of CNT packing are clearly seen in acoustical images as neighboring pixels of various brightness.

  6. Impulsivity and clinical symptoms among adolescents with non-suicidal self-injury with or without attempted suicide.

    PubMed

    Dougherty, Donald M; Mathias, Charles W; Marsh-Richard, Dawn M; Prevette, Kristen N; Dawes, Michael A; Hatzis, Erin S; Palmes, Guy; Nouvion, Sylvain O

    2009-08-30

    This study examined clinical characteristics and laboratory-measured impulsive behavior of adolescents engaging in either non-suicidal self-injury with (NSSI+SA; n=25) or without (NSSI-Only; n=31) suicide attempts. We hypothesized that adolescent with NSSI+SI would exhibit more severe clinical symptoms and higher levels of behavioral impulsivity compared to adolescents with NSSI-Only. Adolescents were recruited from an inpatient psychiatric hospital unit and the two groups were compared on demographic characteristics, psychopathology, self-reported clinical ratings, methods of non-suicidal self-injury, and two laboratory impulsivity measures. Primary evaluations were conducted during psychiatric hospitalization, and a subset of those tested during hospitalization was retested 4-6 weeks after discharge. During hospitalization, NSSI+SA patients reported worse depression, hopelessness, and impulsivity on standard clinical measures, and demonstrated elevated impulsivity on a reward-directed laboratory measure compared to NSSI-Only patients. In the follow-up analyses, depression, hopelessness, suicidal ideation, and laboratory impulsivity were improved for both groups, but the NSSI+SA group still exhibited significantly more depressive symptoms, hopelessness, and impulsivity than the NSSI-Only group. Risk assessments for adolescents with NSSI+SA should include consideration not only of the severity of clinical symptoms but of the current level impulsivity as well.

  7. Interaction between pulsed discharge and radio frequency discharge burst at atmospheric pressure

    SciTech Connect

    Zhang, Jie; Guo, Ying; Shi, Yuncheng; Zhang, Jing; Shi, J. J.

    2015-08-15

    The atmospheric pressure glow discharges (APGD) with dual excitations in terms of pulsed voltage and pulse-modulation radio frequency (rf) power are studied experimentally between two parallel plates electrodes. Pulse-modulation applied in rf APGD temporally separates the discharge into repetitive discharge bursts, between which the high voltage pulses are introduced to ignite sub-microsecond pulsed discharge. The discharge characteristics and spatio-temporal evolution are investigated by means of current voltage characteristics and time resolved imaging, which suggests that the introduced pulsed discharge assists the ignition of rf discharge burst and reduces the maintain voltage of rf discharge burst. Furtherly, the time instant of pulsed discharge between rf discharge bursts is manipulated to study the ignition dynamics of rf discharge burst.

  8. Impulsivity and sexual assault in college men.

    PubMed

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

    2013-01-01

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

  9. Efficiency Analysis of a High-Specific Impulse Hall Thruster

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    Performance and plasma measurements of the high-specific impulse NASA-173Mv2 Hall thruster were analyzed using a phenomenological performance model that accounts for a partially-ionized plasma containing multiply-charged ions. Between discharge voltages of 300 to 900 V, the results showed that although the net decrease of efficiency due to multiply-charged ions was only 1.5 to 3.0 percent, the effects of multiply-charged ions on the ion and electron currents could not be neglected. Between 300 to 900 V, the increase of the discharge current was attributed to the increasing fraction of multiply-charged ions, while the maximum deviation of the electron current from its average value was only +5/-14 percent. These findings revealed how efficient operation at high-specific impulse was enabled through the regulation of the electron current with the applied magnetic field. Between 300 to 900 V, the voltage utilization ranged from 89 to 97 percent, the mass utilization from 86 to 90 percent, and the current utilization from 77 to 81 percent. Therefore, the anode efficiency was largely determined by the current utilization. The electron Hall parameter was nearly constant with voltage, decreasing from an average of 210 at 300 V to an average of 160 between 400 to 900 V. These results confirmed our claim that efficient operation can be achieved only over a limited range of Hall parameters.

  10. Cotton buds, momentum, and impulse

    NASA Astrophysics Data System (ADS)

    van den Berg, Ed; Nuñez, Jover; Guirit, Alfredo; van Huis, Cor

    2000-01-01

    Here is a simple experiment demonstrating impulse and momentum that was picked up from a Japanese presenter at a physics teacher conference held in Cebu City. We have not been able to trace the experiment farther and have never seen it in print. After student-author Nuñez demonstrated it during an exam on conducting demonstrations, we converted the qualitative idea into a quanitative experiment and even discovered some possibilities for student research. The lab is also suitable as homework, since it uses universally available "equipment" — cotton buds (swabs), drinking straws, and a ruler.

  11. Motor inhibition, reflection impulsivity, and trait impulsivity in pathological skin picking.

    PubMed

    Snorrason, Ívar; Smári, Jakob; Ólafsson, Ragnar P

    2011-09-01

    Pathological skin picking (PSP) is often recognized as an impulse control disorder. The current study sought to investigate the relationship between PSP and different forms of impulsivity. University students that met criteria for PSP (n = 55) and university students without history of PSP (n = 55) answered a multidimensional impulsivity questionnaire (the UPPS Impulsive Behavior Scale) and completed 2 neurocognitive tasks that assess impulsivity (the Stop Signal Task and the Information Sampling Task). The PSP group scored significantly higher than the control group on the negative and positive urgency subscales of the UPPS, but the groups did not differ on other subscales or the neurocognitive tasks. Logistic regression demonstrated that the urgency scales added to the prediction of PSP after negative affect and other forms of impulsivity were adjusted for. The results indicate that PSP sufferers are characterized by emotion-based impulsivity and do not appear to be impulsive in other ways. PMID:21658533

  12. Approximate controllability of nonlinear impulsive differential systems

    NASA Astrophysics Data System (ADS)

    Sakthivel, R.; Mahmudov, N. I.; Kim, J. H.

    2007-08-01

    Many practical systems in physical and biological sciences have impulsive dynamical be- haviours during the evolution process which can be modeled by impulsive differential equations. This paper studies the approximate controllability issue for nonlinear impulsive differential and neutral functional differential equations in Hilbert spaces. Based on the semigroup theory and fixed point approach, sufficient conditions for approximate controllability of impulsive differential and neutral functional differential equations are established. Finally, two examples are presented to illustrate the utility of the proposed result. The results improve some recent results.

  13. 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

  14. Experimental study on thermal characteristics of positive leader discharges using Mach-Zehnder interferometry

    SciTech Connect

    Zhou, X. Zeng, R.; Zhuang, C.; Chen, S.

    2015-06-15

    Leader discharge is one of the main phases in long air gap breakdown, which is characterized by high temperature and high conductivity. It is of great importance to determine thermal characteristics of leader discharges. In this paper, a long-optical-path Mach-Zehnder interferometer was set up to measure the thermal parameters (thermal diameter, gas density, and gas temperature) of positive leader discharges in atmospheric air. IEC standard positive switching impulse voltages were applied to a near-one-meter point-plane air gap. Filamentary channels with high gas temperature and low density corresponding to leader discharges were observed as significant distortions in the interference fringe images. Typical diameters of the entire heated channel range from 1.5 mm to 3.5 mm with an average expansion velocity of 6.7 m/s. In contrast, typical diameters of the intensely heated region with a sharp gas density reduction range from 0.4 mm to 1.1 mm, about one third of the entire heated channel. The radial distribution of the gas density is calculated from the fringe displacements by performing an Abel inverse transform. The typical calculated gas density reduction in the center of a propagating leader channel is 80% to 90%, corresponding to a gas temperature of 1500 K to 3000 K based on the ideal gas law. Leaders tend to terminate if the central temperature is below 1500 K.

  15. Experimental study on thermal characteristics of positive leader discharges using Mach-Zehnder interferometry

    NASA Astrophysics Data System (ADS)

    Zhou, X.; Zeng, R.; Zhuang, C.; Chen, S.

    2015-06-01

    Leader discharge is one of the main phases in long air gap breakdown, which is characterized by high temperature and high conductivity. It is of great importance to determine thermal characteristics of leader discharges. In this paper, a long-optical-path Mach-Zehnder interferometer was set up to measure the thermal parameters (thermal diameter, gas density, and gas temperature) of positive leader discharges in atmospheric air. IEC standard positive switching impulse voltages were applied to a near-one-meter point-plane air gap. Filamentary channels with high gas temperature and low density corresponding to leader discharges were observed as significant distortions in the interference fringe images. Typical diameters of the entire heated channel range from 1.5 mm to 3.5 mm with an average expansion velocity of 6.7 m/s. In contrast, typical diameters of the intensely heated region with a sharp gas density reduction range from 0.4 mm to 1.1 mm, about one third of the entire heated channel. The radial distribution of the gas density is calculated from the fringe displacements by performing an Abel inverse transform. The typical calculated gas density reduction in the center of a propagating leader channel is 80% to 90%, corresponding to a gas temperature of 1500 K to 3000 K based on the ideal gas law. Leaders tend to terminate if the central temperature is below 1500 K.

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

    ERIC Educational Resources Information Center

    Cyders, Melissa A.

    2013-01-01

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

  17. Multifractal analysis of visualized room impulse response for detecting early reflections.

    PubMed

    Pavlović, Milan; Ristić, Dragan M; Reljin, Irini; Mijić, Miomir

    2016-05-01

    This paper describes an improved method for detecting early reflections in the initial part of the room impulse response using multifractals. The proposed method uses the two-dimensional multifractal analysis. The room impulse response is visualized as a spectrogram image which is then subjected to the multifractal analysis. The algorithm is based on describing local regularity in the image using distribution of Hölder exponents. The time positions of the selected Hölder exponents in the image are utilized in detecting early reflections. The obtained results show better efficiency of the proposed algorithm compared to the previous one-dimensional multifractal analysis based algorithm. PMID:27250194

  18. Impulsive model for reactive collisions

    NASA Technical Reports Server (NTRS)

    Marron, M. T.; Bernstein, R. B.

    1972-01-01

    A simple classical mechanical model of the reactive scattering of a structureless atom A and a quasi-diatomic BC is developed which takes full advantage of energy, linear and angular momentum conservation relations but introduces a minimum of further assumptions. These are as follows: (1) the vibrational degree of freedom of the reactant (BC) and product (AB) molecules is suppressed, so the change in vibrational energy is simply a parameter; (2) straight-line trajectories are assumed outside of a reaction shell; (3) within this zone, momentum transfer occurs impulsively (essentially instantaneously) following mass transfer; (4) the impulse, which may be either positive or negative, is directed along the BC axis, which may, however, assume all orientations with respect to the incident relative velocity. The model yields differential and total cross sections and product rotational energy distributions for a given collision exoergicity Q, or for any known distribution over Q. Numerical results are presented for several prototype reactions whose dynamics have been well-studied.

  19. Ulcerative colitis - discharge

    MedlinePlus

    Inflammatory bowel disease - ulcerative colitis - discharge; Ulcerative proctitis - discharge; Colitis - discharge ... were in the hospital because you have ulcerative colitis. This is a swelling of the inner lining ...

  20. Trait impulsivity is related to ventral ACC and amygdala activity during primary reward anticipation.

    PubMed

    Kerr, Kara L; Avery, Jason A; Barcalow, Joel C; Moseman, Scott E; Bodurka, Jerzy; Bellgowan, Patrick S F; Simmons, W Kyle

    2015-01-01

    Trait impulsivity is characterized by behavioral disinhibition and rash decision-making that contribute to many maladaptive behaviors. Previous research demonstrates that trait impulsivity is related to the activity of brain regions underlying reward sensitivity and emotion regulation, but little is known about this relationship in the context of immediately available primary reward. This is unfortunate, as impulsivity in these contexts can lead to unhealthy behaviors, including poor food choices, dangerous drug use and risky sexual practices. In addition, little is known about the relationship between integration of reward and affective neurocircuitry, as measured by resting-state functional connectivity, and trait impulsivity in everyday life, as measured with a commonly used personality inventory. We therefore asked healthy adults to undergo a functional magnetic resonance imaging task in which they saw cues indicating the imminent oral administration of rewarding taste, as well as a resting-state scan. Trait impulsivity was associated with increased activation during anticipation of primary reward in the anterior cingulate cortex (ACC) and amygdala. Additionally, resting-state functional connectivity between the ACC and the right amygdala was negatively correlated with trait impulsivity. These findings demonstrate that trait impulsivity is related not only to ACC-amygdala activation but also to how tightly coupled these regions are to one another. PMID:24526181

  1. Trait impulsivity is related to ventral ACC and amygdala activity during primary reward anticipation

    PubMed Central

    Kerr, Kara L.; Avery, Jason A.; Barcalow, Joel C.; Moseman, Scott E.; Bodurka, Jerzy; Bellgowan, Patrick S. F.

    2015-01-01

    Trait impulsivity is characterized by behavioral disinhibition and rash decision-making that contribute to many maladaptive behaviors. Previous research demonstrates that trait impulsivity is related to the activity of brain regions underlying reward sensitivity and emotion regulation, but little is known about this relationship in the context of immediately available primary reward. This is unfortunate, as impulsivity in these contexts can lead to unhealthy behaviors, including poor food choices, dangerous drug use and risky sexual practices. In addition, little is known about the relationship between integration of reward and affective neurocircuitry, as measured by resting-state functional connectivity, and trait impulsivity in everyday life, as measured with a commonly used personality inventory. We therefore asked healthy adults to undergo a functional magnetic resonance imaging task in which they saw cues indicating the imminent oral administration of rewarding taste, as well as a resting-state scan. Trait impulsivity was associated with increased activation during anticipation of primary reward in the anterior cingulate cortex (ACC) and amygdala. Additionally, resting-state functional connectivity between the ACC and the right amygdala was negatively correlated with trait impulsivity. These findings demonstrate that trait impulsivity is related not only to ACC-amygdala activation but also to how tightly coupled these regions are to one another. PMID:24526181

  2. Self-reported impulsivity is negatively correlated with amygdalar volumes in cocaine dependence

    PubMed Central

    Mei, Songli; Xu, Jiansong; Carroll, Kathleen M.; Potenza, Marc N.

    2015-01-01

    Although impulsivity has been associated with cocaine dependence and other addictive behaviors, the biological factors underlying impulsivity have yet to be precisely determined. This study aimed to examine relationships between impulsivity and volumes of the amygdala and hippocampus in cocaine-dependent and healthy comparison individuals. The Barratt Impulsiveness Scale (BIS-11) was used to assess impulsivity. FreeSurfer was used to assess amygdalar and hippocampal volumes from high-resolution structural magnetic resonance images. Relative to healthy comparison subjects, cocaine-dependent individuals scored higher on all three subscales of BIS-11 but did not differ from healthy comparison subjects in amygdalar or hippocampal volumes. Cocaine-dependent individuals showed significant negative correlations between amygdalar volumes and scores on the BIS-11 Attentional subscale, and this relationship differed significantly from the non-significant relationship in healthy comparison subjects. As individual differences in amygdalar structure may contribute to the high impulsivity observed in cocaine-dependent individuals, the findings suggest that future studies should assess the extent to which therapies that target impulsivity in cocaine dependence may operate through the amygdala or alter its structure or function. PMID:26187551

  3. Analysis of impulse signals with Hylaty ELF station

    NASA Astrophysics Data System (ADS)

    Kulak, A.; Mlynarczyk, J.; Ostrowski, M.; Kubisz, J.; Michalec, A.

    2012-04-01

    Lighting discharges generate electromagnetic field pulses that propagate in the Earth-ionosphere waveguide. The attenuation in the ELF range is so small that the pulses originating from strong atmospheric discharges can be observed even several thousand kilometers away from the individual discharge. The recorded waveform depends on the discharge process, the Earth-ionosphere waveguide properties on the source-receiver path, and the transfer function of the receiver. If the distance from the source is known, an inverse method can be used for reconstructing the current moment waveform and the charge moment of the discharge. In order to reconstruct the source parameters from the recorded signal a reliable model of the radio wave propagation in the Earth-ionosphere waveguide as well as practical signal processing techniques are necessary. We present two methods, both based on analytical formulas. The first method allows for fast calculation of the charge moment of relatively short atmospheric discharges. It is based on peak amplitude measurement of the recorded magnetic component of the ELF EM field and it takes into account the receiver characteristics. The second method, called "inverse channel method" allows reconstructing the complete current moment waveform of strong atmospheric discharges that exhibit the continuing current phase, such as Gigantic Jets and Sprites. The method makes it possible to fully remove from the observed waveform the distortions related to the receiver's impulse response as well as the influence of the Earth-ionosphere propagation channel. Our ELF station is equipped with two magnetic antennas for Bx and By components measurement in the 0.03 to 55 Hz frequency range. ELF Data recording is carried out since 1993, with continuous data acquisition since 2005. The station features low noise level and precise timing. It is battery powered and located in the sparsely populated area, far from major electric power lines, which results in high

  4. Reliability and Validity of Measures of Impulsive Choice and Impulsive Action in Smokers Trying to Quit

    PubMed Central

    McCarthy, Danielle E.; Bold, Krysten W.; Minami, Haruka; Yeh, Vivian M.; Rutten, Emily; Nadkarni, Shruti G.; Chapman, Gretchen B.

    2016-01-01

    Cross-sectional research suggests that smokers are more impulsive than are non-smokers, but few studies have examined relations between impulsiveness and later success in quitting smoking. The purpose of this study was to investigate the reliability and predictive validity of facets of impulsiveness in adult smokers trying to quit. Baseline behavioral measures of impulsive choice (assessed with a delay discounting task) and impulsive action (assessed with a measure of behavioral disinhibition) were used as predictors of smoking cessation success over 12 weeks. The sample included 116 adult (18 years old or older) daily smokers from central New Jersey. Impulsive choice, impulsive action, and self-reported impulsiveness were not significantly related to one another at baseline. Impulsive choice had high test-retest reliability from pre- to post-quit, whereas impulsive action was less stable. Test-retest reliability from pre-quit to three weeks post-quit was moderated by achievement of seven-day abstinence. Baseline impulsive action was significantly negatively related to quitting for at least one day in the first two weeks of a quit attempt and of prolonged abstinence (no relapse over the next 10 weeks). Baseline impulsive choice was robustly associated with biochemically verified seven-day point-prevalence abstinence 12 weeks post-quit, such that those with lower delay discounting were more likely to achieve abstinence. Facets of impulsiveness appear to function largely independently in adult smokers, as indicated by their lack of inter-correlation, differential stability, and differential relations with abstinence. Impulsive action may impede initial quitting, whereas impulsive choice may be an obstacle to maintaining lasting abstinence. PMID:26751623

  5. Effect of management of patients with Anorexia and Bulimia nervosa on symptoms and impulsive behavior.

    PubMed

    Sernec, Karin; Tomori, Martina; Zalar, Bojan

    2010-12-01

    The aim of the study was to provide further and up to date information on the evaluation of the management of Anorexia and Bulimia nervosa at the Eating Disorders Unit (EDU) of the Ljubljana Psychiatric Clinic, based upon detailed assessment of the eating disorders specific and non specific symptoms of impulsive behaviors, highly correlated with these entities. 34 female patients with anorexia (restrictive or purgative type) and 38 female patients with Bulimia nervosa (purgative or non-purgative type) undergoing hospital treatment at the EDU were evaluated upon admission, as well as upon discharge and three and six months after discharge, using the Eating Disorder Questionnaire. Upon discharge a marked decrease in the overall symptoms was noted. The differences in symptoms incidences between the two groups were significantly specific for the individual form of eating disorder, especially upon admission, and were more pronounced in anorexia group. In later measurements, performed during the period of three and six months after discharge, a mild trend of increase in the disorder specific symptoms was detected in both groups, but was not statistically significant. In addition to binging on food, striking, quarreling and spending sprees are characteristics of patients with eating disorders, which in particular apply to the Bulimia nervosa group. Apart from the disorder specific symptoms, impulsive behavior was also reduced during study period, while the difference in its occurrence between the two groups gradually became non-significant. The management of patients with eating disorders at the EDU was successful in both groups, confirmed by an intense reduction of the disorder specific symptoms, impulsive behavior and increased stability recorded three and six months after discharge. The study strongly suggests that the effect of treatment regime for eating disorders can be predicted by careful assessment of the relevant symptoms and impulsive behavioral patterns.

  6. Hyperkinetic Impulse Disorder in Children's Behavior Problems

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  7. Solar Impulse's Solar-Powered Plane

    ScienceCinema

    Moniz, Ernest; Piccard, Bertrand; Reicher, Dan

    2016-07-12

    Solar Impulse lands in Washington, DC at Washington Dulles International Airport as part of its journey across the United States. Secretary Ernest Moniz speaks about how advancements like those at the Department of Energy are leading the way for innovations like the solar-powered plane. Footage of the solar-powered plane courtesy of Solar Impulse.

  8. Temporal Preparation, Response Inhibition and Impulsivity

    ERIC Educational Resources Information Center

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

    2010-01-01

    Temporal preparation and impulsivity involve overlapping neural structures (prefrontal cortex) and cognitive functions (response inhibition and time perception), however, their interrelations had not been investigated. We studied such interrelations by comparing the performance of groups with low vs. high non-clinical trait impulsivity during a…

  9. Semicontinuity of attractors for impulsive dynamical systems

    NASA Astrophysics Data System (ADS)

    Bonotto, E. M.; Bortolan, M. C.; Collegari, R.; Czaja, R.

    2016-10-01

    In this paper we introduce the concept of collective tube conditions which assures a suitable behaviour for a family of dynamical systems close to impulsive sets. Using the collective tube conditions, we develop the theory of upper and lower semicontinuity of global attractors for a family of impulsive dynamical systems.

  10. Covert Suicidal Impulses in Maternally Deprived Children.

    ERIC Educational Resources Information Center

    Kliman, Gilbert; Lubin, Harriet

    This paper discusses the development of suicidal impulses in children who have lost their mothers due to abandonment or death. The paper is based on two psychoanalytic case studies, in which the children were in therapy when the first suicidal impulses emerged. A pattern is described in which bereaved children's intense wishes to have their…

  11. Impulsivity, School Context, and School Misconduct

    ERIC Educational Resources Information Center

    Vogel, Matt; Barton, Michael S.

    2013-01-01

    Impulsivity holds a central place in the explanations of adolescent delinquency. Recent research suggests that neighborhood characteristics, particularly SES (socioeconomic status), perceived supervision, and collective efficacy, moderate the association between impulsivity and delinquency. However, findings to date have been equivocal, and the…

  12. Impulsivity and Psychoeducational Intervention in Hyperactive Children.

    ERIC Educational Resources Information Center

    Brown, Ronald T.

    1980-01-01

    Two psychoeducational procedures were investigated for their effects on impulsivity in 120 hyperactive children in two groups: those receiving stimulant drug therapy and those not receiving stimulant drug therapy. Results indicated that the use of psychoeducational treatment approaches are of value in altering the impulsive responses of…

  13. Impulsivity: Self-Report and Performance Measure

    ERIC Educational Resources Information Center

    Cairns, E.; Harbison, J. I.

    1975-01-01

    The present study assessed the relationship between impulsivity as measured by the Matching Familiar Figures test (MFF) and by the impulsivity (IMP) factor derived from the Junior Eysenck Personality Inventory (JEPI) items identified by S. N. Bennet in 1973. (Author/RK)

  14. Assessing impulsivity changes in Alzheimer disease.

    PubMed

    Rochat, Lucien; Delbeuck, Xavier; Billieux, Joël; d'Acremont, Mathieu; Van der Linden, Anne-Claude Juillerat; Van der Linden, Martial

    2008-01-01

    Impulsive behaviors are common in brain-damaged patients including those with neurodegenerative diseases such as Alzheimer disease (AD). The objective of this study was to develop and validate a short version of the UPPS Impulsive Behavior Scale assessing changes on 4 different dimensions of impulsivity, namely urgency, (lack of) premeditation, (lack of) perseverance, and sensation seeking, arising in the course of a neurodegenerative disease. To this end, caregivers of 83 probable AD patients completed a short questionnaire adapted from the UPPS Impulsive Behavior Scale. Exploratory and confirmatory factor analyses of the data were performed and revealed that a model with 4 distinct but related latent variables corresponding to 4 different dimensions of impulsivity fit the data best. Furthermore, the results showed that lack of perseverance, followed by lack of premeditation and urgency, increased after the onset of the disease, whereas sensation seeking decreased. Overall, the multifaceted nature of impulsivity was confirmed in a sample of AD patients, whose caregivers reported significant changes regarding each facet of impulsivity. Consequently, the short version of the UPPS Impulsive Behavior Scale opens up interesting prospects for a better comprehension of behavioral symptoms of dementia. PMID:18580596

  15. Solar Impulse's Solar-Powered Plane

    SciTech Connect

    Moniz, Ernest; Piccard, Bertrand; Reicher, Dan

    2013-07-08

    Solar Impulse lands in Washington, DC at Washington Dulles International Airport as part of its journey across the United States. Secretary Ernest Moniz speaks about how advancements like those at the Department of Energy are leading the way for innovations like the solar-powered plane. Footage of the solar-powered plane courtesy of Solar Impulse.

  16. Gastroesophageal reflux - discharge

    MedlinePlus

    Peptic esophagitis - discharge; Reflux esophagitis - discharge; GERD - discharge; Heartburn - chronic - discharge ... You have gastroesophageal reflux disease (GERD). This is a condition in which food or liquid travels backwards from the stomach to the ...

  17. Ventriculoperitoneal shunt - discharge

    MedlinePlus

    ... ventriculoperitoneal - discharge; VP shunt - discharge; Shunt revision - discharge; Hydrocephalus shunt placement - discharge ... Your child has hydrocephalus and needed a shunt placed to drain excess fluid and relieve pressure in the brain. This buildup of brain ...

  18. Gastric bypass surgery - discharge

    MedlinePlus

    ... bypass - discharge; Gastric bypass - Roux-en-Y - discharge; Obesity gastric bypass discharge; Weight loss - gastric bypass discharge ... al. Bariatric surgery versus non-surgical treatment for obesity: a systematic review and meta-analysis of randomised ...

  19. Effects of cannabis on impulsivity: a systematic review of neuroimaging findings.

    PubMed

    Wrege, Johannes; Schmidt, Andre; Walter, Anna; Smieskova, Renata; Bendfeldt, Kerstin; Radue, Ernst-Wilhelm; Lang, Undine E; Borgwardt, Stefan

    2014-01-01

    We conducted a systematic review to assess the evidence for specific effects of cannabis on impulsivity, disinhibition and motor control. The review had a specific focus on neuroimaging findings associated with acute and chronic use of the drug and covers literature published up until May 2012. Seventeen studies were identified, of which 13 met the inclusion criteria; three studies investigated acute effects of cannabis (1 fMRI, 2 PET), while six studies investigated non-acute functional effects (4 fMRI, 2 PET), and four studies investigated structural alterations. Functional imaging studies of impulsivity studies suggest that prefrontal blood flow is lower in chronic cannabis users than in controls. Studies of acute administration of THC or marijuana report increased brain metabolism in several brain regions during impulsivity tasks. Structural imaging studies of cannabis users found differences in reduced prefrontal volumes and white matter integrity that might mediate the abnormal impulsivity and mood observed in marijuana users. To address the question whether impulsivity as a trait precedes cannabis consumption or whether cannabis aggravates impulsivity and discontinuation of usage more longitudinal study designs are warranted.

  20. Effects of Cannabis on Impulsivity: A Systematic Review of Neuroimaging Findings

    PubMed Central

    Wrege, Johannes; Schmidt, André; Walter, Anna; Smieskova, Renata; Bendfeldt, Kerstin; Radue, Ernst-Wilhelm; Lang, Undine E.; Borgwardt, Stefan

    2014-01-01

    We conducted a systematic review to assess the evidence for specific effects of cannabis on impulsivity, disinhibition and motor control. The review had a specific focus on neuroimaging findings associated with acute and chronic use of the drug and covers literature published up until May 2012. Seventeen studies were identified, of which 13 met the inclusion criteria; three studies investigated acute effects of cannabis (1 fMRI, 2 PET), while six studies investigated non-acute functional effects (4 fMRI, 2 PET), and four studies investigated structural alterations. Functional imaging studies of impulsivity studies suggest that prefrontal blood flow is lower in chronic cannabis users than in controls. Studies of acute administration of THC or marijuana report increased brain metabolism in several brain regions during impulsivity tasks. Structural imaging studies of cannabis users found differences in reduced prefrontal volumes and white matter integrity that might mediate the abnormal impulsivity and mood observed in marijuana users. To address the question whether impulsivity as a trait precedes cannabis consumption or whether cannabis aggravates impulsivity and discontinuation of usage more longitudinal study designs are warranted. PMID:23829358

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

    PubMed

    Perry, J Christopher; Körner, Annett C

    2011-10-01

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

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

    PubMed

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

    2015-04-01

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

  3. Brain functional connectivity changes in children that differ in impulsivity temperamental trait

    PubMed Central

    Inuggi, Alberto; Sanz-Arigita, Ernesto; González-Salinas, Carmen; Valero-García, Ana V.; García-Santos, Jose M.; Fuentes, Luis J.

    2014-01-01

    Impulsivity is a core personality trait forming part of normal behavior and contributing to adaptive functioning. However, in typically developing children, altered patterns of impulsivity constitute a risk factor for the development of behavioral problems. Since both pathological and non-pathological states are commonly characterized by continuous transitions, we used a correlative approach to investigate the potential link between personality and brain dynamics. We related brain functional connectivity of typically developing children, measured with magnetic resonance imaging at rest, with their impulsivity scores obtained from a questionnaire completed by their parents. We first looked for areas within the default mode network (DMN) whose functional connectivity might be modulated by trait impulsivity. Then, we calculated the functional connectivity among these regions and the rest of the brain in order to assess if impulsivity trait altered their relationships. We found two DMN clusters located at the posterior cingulate cortex and the right angular gyrus which were negatively correlated with impulsivity scores. The whole-brain correlation analysis revealed the classic network of correlating and anti-correlating areas with respect to the DMN. The impulsivity trait modulated such pattern showing that the canonical anti-phasic relation between DMN and action-related network was reduced in high impulsive children. These results represent the first evidence that the impulsivity, measured as personality trait assessed through parents' report, exerts a modulatory influence over the functional connectivity of resting state brain networks in typically developing children. The present study goes further to connect developmental approaches, mainly based on data collected through the use of questionnaires, and behavioral neuroscience, interested in how differences in brain structure and functions reflect in differences in behavior. PMID:24834038

  4. Brain functional connectivity changes in children that differ in impulsivity temperamental trait.

    PubMed

    Inuggi, Alberto; Sanz-Arigita, Ernesto; González-Salinas, Carmen; Valero-García, Ana V; García-Santos, Jose M; Fuentes, Luis J

    2014-01-01

    Impulsivity is a core personality trait forming part of normal behavior and contributing to adaptive functioning. However, in typically developing children, altered patterns of impulsivity constitute a risk factor for the development of behavioral problems. Since both pathological and non-pathological states are commonly characterized by continuous transitions, we used a correlative approach to investigate the potential link between personality and brain dynamics. We related brain functional connectivity of typically developing children, measured with magnetic resonance imaging at rest, with their impulsivity scores obtained from a questionnaire completed by their parents. We first looked for areas within the default mode network (DMN) whose functional connectivity might be modulated by trait impulsivity. Then, we calculated the functional connectivity among these regions and the rest of the brain in order to assess if impulsivity trait altered their relationships. We found two DMN clusters located at the posterior cingulate cortex and the right angular gyrus which were negatively correlated with impulsivity scores. The whole-brain correlation analysis revealed the classic network of correlating and anti-correlating areas with respect to the DMN. The impulsivity trait modulated such pattern showing that the canonical anti-phasic relation between DMN and action-related network was reduced in high impulsive children. These results represent the first evidence that the impulsivity, measured as personality trait assessed through parents' report, exerts a modulatory influence over the functional connectivity of resting state brain networks in typically developing children. The present study goes further to connect developmental approaches, mainly based on data collected through the use of questionnaires, and behavioral neuroscience, interested in how differences in brain structure and functions reflect in differences in behavior.

  5. Impulsivity relates to striatal gray matter volumes in humans: evidence from a delay discounting paradigm.

    PubMed

    Tschernegg, Melanie; Pletzer, Belinda; Schwartenbeck, Philipp; Ludersdorfer, Philipp; Hoffmann, Uta; Kronbichler, Martin

    2015-01-01

    Time-stable personality traits, such as impulsivity and its relationship with functional and structural brain alterations, have gained much attention in the recent literature. Evidence from functional neuroimaging data implies an association between impulsivity and cortical as well as subcortical areas of the reward system. Discounting future rewards during impulsive decisions can be related to activation in the orbitofrontal cortex and striatum. Cortical structural changes in prefrontal regions have been found for introspective impulsivity measures. The present study focuses on brain regions associated with delay discounting to investigate structural manifestations of trait impulsivity. To test this, seventy subjects underwent structural magnetic resonance imaging (MRI) followed by a behavioral delay discounting task outside of the scanner to measure impulsivity with questions like: "Would you like to have 3€ immediately or 10€ in 5 days?". The amount of smaller-but-sooner decisions was calculated and used as a measure of behavioral impulsivity. Furthermore, we estimated subject's individual delay discounting parameter K reflecting the tendency to discount future rewards. Behaviorally, we found strong evidence in favor of a discounting utility model compared to a standard hyperbolic model of choice valuation. Neuronally, we focused on cortical and subcortical brain structure and investigated the association of behavioral impulsivity with delay discounting tendencies and gray matter volume. Voxel-based morphometric analyses showed positive correlations between delay discounting and gray matter volume in the striatum. Additional analyses using Freesurfer provided evidence for a positive correlation between delay discounting and gray matter volume of the caudate. Taken together, our study provides strong evidence for a structural manifestation of time-stable trait impulsivity in the human brain.

  6. Impulse position control algorithms for nonlinear systems

    SciTech Connect

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

    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 such regimes is the fact that they often arise when parry disturbances acting on technical or economic control system.

  7. Helicopter impulsive noise - Theoretical and experimental status

    NASA Technical Reports Server (NTRS)

    Schmitz, F. H.; Yu, Y. H.

    1986-01-01

    The theoretical and experimental status of helicopter impulsive noise is reviewed. The two major source mechanisms of helicopter impulsive noise are addressed: high-speed impulsive noise and blade-vortex interaction impulsive noise. A thorough physical explanation of both generating mechanism is presented together with model and full-scale measurements of the phenomena. Current theoretical prediction methods are compared with experimental findings of isolated rotor tests. The noise generating mechanism of high speed impulsive noise are fairly well understood - theory and experiment compare nicely over Mach number ranges typical of today's helicopters. For the case of blade-vortex interaction noise, understanding of noise generating mechanisms and theoretical comparison with experiment are less satisfactory. Several methods for improving theory-experiment are suggested.

  8. Helicopter impulsive noise: Theoretical and experimental status

    NASA Technical Reports Server (NTRS)

    Schmitz, F. H.; Yu, Y. H.

    1983-01-01

    The theoretical and experimental status of helicopter impulsive noise is reviewed. The two major source mechanisms of helicopter impulsive noise are addressed: high-speed impulsive noise and blade-vortex interaction impulsive noise. A thorough physical explanation of both generating mechanism is presented together with model and full-scale measurements of the phenomena. Current theoretical prediction methods are compared with experimental findings of isolated rotor tests. The noise generating mechanism of high speed impulsive noise are fairly well understood - theory and experiment compare nicely over Mach number ranges typical of today's helicopters. For the case of blade-vortex interaction noise, understanding of noise generating mechanisms and theoretical comparison with experiment are less satisfactory. Several methods for improving theory-experiment are suggested.

  9. Helicopter impulsive noise - Theoretical and experimental status

    NASA Technical Reports Server (NTRS)

    Schmitz, F. H.; Yu, Y. H.

    1986-01-01

    The theoretical and experimental status of helicopter impulsive noise is reviewed. The two major source mechanisms of helicopter impulsive noise are addressed: high-speed impulsive noise and blade-vortex interaction impulsive noise. A thorough physical explanation of both generating mechanisms is presented together with model and full-scale measurements of the phenomena. Current theoretical prediction methods are compared with experimental findings of isolated rotor tests. The noise generating mechanisms of high speed impulsive noise are fairly well understood - theory and experiment compare nicely over Mach number ranges typical of today's helicopters. For the case of blade-vortex interaction noise, understanding of noise generating mechanisms and theoretical comparison with experiment are less satisfactory. Several methods for improving theory/experiment are suggested.

  10. Successful restrained eating and trait impulsiveness.

    PubMed

    van Koningsbruggen, Guido M; Stroebe, Wolfgang; Aarts, Henk

    2013-01-01

    Restrained eaters with high scores on the Perceived Self-Regulatory Success in Dieting Scale (PSRS) are more successful than low scorers in regulating their food intake. According to the theory of temptation-elicited goal activation (Fishbach, Friedman, & Kruglanski, 2003), they have become successful because, due to earlier repeated instances of successful self-control, they formed an associative link between temptations and thoughts of dieting. It is unclear, however, why they should have been more successful in earlier attempts at self-control than their unsuccessful counterparts. We examined whether trait impulsiveness plays a role by investigating the associations between dietary restraint, trait impulsiveness, and PSRS. Results showed that the interaction between dietary restraint and impulsiveness predicted dieting success: A lower level of impulsiveness was associated with greater dieting success among restrained eaters. These results suggest that restrained eaters who are less impulsive are more likely to become successful restrained eaters as identified with the PSRS.

  11. Conversion of Impulse Voltage Generator Into Steep Wave Impulse Test-Equipment

    NASA Astrophysics Data System (ADS)

    Khan, Mohammed Zaid; Tanwar, Surender Singh; Dayama, Ravindra; Choudhary, Rahul Raj; Mangal, Ravindra

    This paper demonstrates the alternative measures to generate the Steep wave impulse by using Impulse Voltage Generator (IVG) for high voltage testing of porcelain insulators. The modification of IVG by incorporating compensation of resistor, inductor, and capacitor has been achieved and further performance of the modified system has been analyzed by applying the generated lightning impulse and analyzing the electrical characteristics of impulse waves under standard lightning and fast rise multiple lightning waveform to determine the effect to improve rise time. The advantageous results have been received and being reported such as increase in overshoot compensation, increase in capacitive and inductive load ranges. Such further reduces the duration of oscillations of standard impulse voltages. The reduction in oscillation duration of steep front impulse voltages may be utilized in up gradation of Impulse Voltage Generator System. Stray capacitance could further be added in order to get the minimized difference of measurement between simulation and the field establishment.

  12. Interstitial lung disease - adults - discharge

    MedlinePlus

    Diffuse parenchymal lung disease - discharge; Alveolitis - discharge; Idiopathic pulmonary pneumonitis - discharge; IPP - discharge; Chronic interstitial lung - discharge; Chronic respiratory interstitial lung - ...

  13. Solar impulsive energetic electron events

    NASA Astrophysics Data System (ADS)

    Wang, Linghua

    The Sun is capable of accelerating ions from ~ tens of keV up to tens of GeV and electrons from ~ tens of eV up to hundreds of MeVs in transient events such as flares and fast coronal mass ejections (CMEs). The energized particles escaping into the interplanetary medium are referred to as Solar Energetic Particle (SEP) events. The great majority of SEP events are impulsive SEP events that are dominated by ~1-100 keV electrons and ~MeV/nucleon ion emissions, with enhanced 3 He/ 4 He ratios up to 10 4 times the coronal values (also called electron/ 3 He-rich SEP events). This thesis is focused on solar impulsive energetic electron events, the electron part of impulsive SEP events, using electron observations from the 3-D Plasma and Energetic Particle instrument (3DP) on the WIND spacecraft near the Earth. First, I present the first comprehensive statistical study of solar energetic electron events over almost one solar cycle. I find that the occurrence rate of solar electron events shows a strong solar-cycle variation; after correction for the background effect, the estimated occurrence frequency exhibits a good power-law distribution, and the estimated occurrence rate near the Earth is ~1000/year at solar maximum and ~30/year at solar minimum for the instrumental sensitivity (~2.9×10^-4 (cm 2 s str eV) -1 for the 40 keV channel) of WIND/3DP, about one order of magnitude larger than the observed occurrence rate. Solar energetic electron events have a one-to-one association with type III radio bursts and a poor association with flares, but a close association with 3 He- rich ion emissions. These 3 He-rich electron events also have a poor association with flares but a close (~ 60%) association with west-limb CMEs. Then I present two case studies: one investigating the temporal relationship between solar impulsive electrons and type III radio emissions, and the second studying the temporal relationship between solar impulsive electrons and 3 He- rich ions. For both

  14. Role of secondary emission on discharge dynamics in an atmospheric pressure dielectric barrier discharge

    SciTech Connect

    Tay, W. H.; Kausik, S. S.; Yap, S. L.; Wong, C. S.

    2014-04-15

    The discharge dynamics in an atmospheric pressure dielectric barrier discharge (DBD) is studied in a DBD reactor consisting of a pair of stainless steel parallel plate electrodes. The DBD discharge has been generated by a 50 Hz ac high voltage power source. The high-speed intensified charge coupled device camera is used to capture the images of filaments occurring in the discharge gap. It is observed that frequent synchronous breakdown of micro discharges occurs across the discharge gap in the case of negative current pulse. The experimental results reveal that secondary emissions from the dielectric surface play a key role in the synchronous breakdown of plasma filaments.

  15. Behavioral Impulsivity in Obsessive-Compulsive Disorder.

    PubMed

    Abramovitch, Amitai; McKay, Dean

    2016-09-01

    Background Grassi et al. (2015) collected data to examine impulsivity in individuals with obsessive-compulsive disorder (OCD) compared to nonpsychiatric controls. Their aim was to examine whether OCD may be fully captured by the behavioral addiction model, using the prototypical mechanism underlying drug addiction as their framework. Based on their findings, Grassi et al. concluded that OCD shares behavioral components with addictions, particularly behavioral impulsivity and risky decision making. Furthermore, the authors suggested that this model may be superior to the prevailing psychological model of OCD. Findings We argue that based on the nature of their data as well as the current dominant conceptualization of OCD in the literature, this conclusion is untenable. The authors inferred behavioral impulsivity, whereas their main finding was concerning cognitive impulsivity or difficulties in planning. Such items on the Barratt impulsiveness scale have been shown in other research to overpredict behavioral impulsive tendencies in OCD, where the nature of the condition involves doubting of action and a conservative estimate of how one's cognitions may impact behavior. Conclusions We conclude that similar to drug addiction, compulsive rituals in OCD may be governed by a negative reinforcement mechanism; the available data indicate that OCD does not share the two main components seen in addiction, namely, behavioral impulsivity and risky decision making. PMID:27156379

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

    PubMed Central

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

    2009-01-01

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

  17. Psychosocial predictors of impulsivity in alcohol-dependent patients

    PubMed Central

    Jakubczyk, Andrzej; Klimkiewicz, Anna; Mika, Katarzyna; Bugaj, Marcin; Konopa, Aleksandra; Podgórska, Anna; Brower, Kirk J.; Wojnar, Marcin

    2012-01-01

    Impulsivity is an important risk factor of severe course of alcohol dependence. However, the significance of environmental determinants of impulsivity has been underestimated. The aim of the study was to identify psychosocial factors increasing the level of impulsivity in alcoholics. Levels of impulsivity were measured in 304 alcohol-dependent patients. Stop-signal task was used to assess behavioral impulsivity, and Barratt Impulsiveness Scale to measure global and cognitive impulsivity. Correlations between impulsivity and psychosocial variables were examined. A significant association between level of impulsivity and severity of psychopathological symptoms were observed. Patients who reported childhood sexual or physical abuse, lower social support, more severe course of alcohol dependence were more impulsive, especially in cognitive domain. When entered into a linear regression analysis model, severity of alcohol dependence, psychopathology and childhood physical abuse remained significant. These results suggest that psychosocial variables are important factors associated with high levels of impulsivity in alcohol-dependent patients. PMID:23274294

  18. Psychosocial predictors of impulsivity in alcohol-dependent patients.

    PubMed

    Jakubczyk, Andrzej; Klimkiewicz, Anna; Mika, Katarzyna; Bugaj, Marcin; Konopa, Aleksandra; Podgórska, Anna; Brower, Kirk J; Wojnar, Marcin

    2013-01-01

    Impulsivity is an important risk factor of severe course of alcohol dependence. However, the significance of environmental determinants of impulsivity has been underestimated. The aim of this study was to identify psychosocial factors increasing the level of impulsivity in alcoholics. Levels of impulsivity were measured in 304 alcohol-dependent patients. The stop-signal task was used to assess behavioral impulsivity, and the Barratt Impulsiveness Scale, to measure global and cognitive impulsivity. Correlations between impulsivity and psychosocial variables were examined. A significant association between level of impulsivity and severity of psychopathological symptoms was observed. Patients who reported childhood sexual or physical abuse, lower social support, and more severe course of alcohol dependence were more impulsive, especially in the cognitive domain. When entered into a linear regression analysis model, severity of alcohol dependence, psychopathology, and childhood physical abuse remained significant. These results suggest that psychosocial variables are important factors associated with high levels of impulsivity in alcohol-dependent patients.

  19. Psychosocial predictors of impulsivity in alcohol-dependent patients.

    PubMed

    Jakubczyk, Andrzej; Klimkiewicz, Anna; Mika, Katarzyna; Bugaj, Marcin; Konopa, Aleksandra; Podgórska, Anna; Brower, Kirk J; Wojnar, Marcin

    2013-01-01

    Impulsivity is an important risk factor of severe course of alcohol dependence. However, the significance of environmental determinants of impulsivity has been underestimated. The aim of this study was to identify psychosocial factors increasing the level of impulsivity in alcoholics. Levels of impulsivity were measured in 304 alcohol-dependent patients. The stop-signal task was used to assess behavioral impulsivity, and the Barratt Impulsiveness Scale, to measure global and cognitive impulsivity. Correlations between impulsivity and psychosocial variables were examined. A significant association between level of impulsivity and severity of psychopathological symptoms was observed. Patients who reported childhood sexual or physical abuse, lower social support, and more severe course of alcohol dependence were more impulsive, especially in the cognitive domain. When entered into a linear regression analysis model, severity of alcohol dependence, psychopathology, and childhood physical abuse remained significant. These results suggest that psychosocial variables are important factors associated with high levels of impulsivity in alcohol-dependent patients. PMID:23274294

  20. Transition Region and Chromospheric Signatures of Impulsive Heating Events

    NASA Astrophysics Data System (ADS)

    Warren, Harry; Reep, Jeffrey; Crump, Nicholas

    2016-05-01

    We exploit the high spatial resolution and high cadence of the Interface Region Imaging Spectrograph (IRIS) to investigate the response of the transition region and chromosphere to energy deposition during several small flares. We find that during the impulsive phase of these events the intensities of the C II 1334.535 and Si IV 1402.770 A emission lines are characterized by numerous, small-scale impulsive bursts typically lasting 60 s or less followed by a slower decay over several minutes. These variations in intensity are usually accompanied by impulsive redshifts of 20-40 km/s, although some blueshifted profiles are also observed. For one particularly well observed event we combine the IRIS observations with co-temporal measurements of hard X-ray emission from RHESSSI, transition region density from EIS, and high-temperature coronal loops with XRT and AIA to constrain 1D hydrodynamic models of loop evolution. Many aspects of the observations can be explained with simple heating scenarios, but some cannot. The simulated Doppler shifts, for example, show very short-duration redshifts during the initial phase of the heating while the observed redshifts persist over several minutes.

  1. The Subthalamic Nucleus, Limbic Function, and Impulse Control.

    PubMed

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

    2015-12-01

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

  2. An Injector for the Variable Specific Impulse Magnetoplasma Rocket

    NASA Astrophysics Data System (ADS)

    Glover, T. W.; Chang-Diaz, F. R.; Squire, J. P.; Chan, A. A.

    1997-11-01

    We present a summary of progress on the development of a plasma injector for NASA's VASIMR (Variable Specific Impulse Magnetoplasma Rocket) engine. The plasma rocket constrains a flowing plasma in an asymmetric magnetic bottle and exhausts it through a magnetic nozzle to produce thrust. The injector is a plasma source located on the axis of symmetry, forward of the series of coils forming the constraining magnetic field. The injector is intended to produce a well-collimated jet of highly ionized plasma which will enter the central cell of the machine through its forward mirror. The prototype design is based on that of a Lorentz Force Accelerator developed as a thruster by the electric propulsion research group at Princeton. Our investigation focuses on the effects of the rocket's magnetic field on the operation of the injector, the effect of a local magnetic field on the discharge behavior, and the effectiveness of discharge initiation by glow discharge versus initiation by ECRH. We evaluate the performance of this prototype injector by comparing the characteristics of the plasma it inserts into the central cell of the engine with the characteristics called for in the design of the plasma rocket.

  3. Spin Stabilized Impulsively Controlled Missile (SSICM)

    NASA Astrophysics Data System (ADS)

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

    1985-12-01

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

  4. [Impulse control disorders in Parkinson's disease].

    PubMed

    Joutsa, Juho; Kaasinen, Valtteri

    2013-01-01

    Of the patients having Parkinson's disease, up to third encounters some degree of impulse control problems and one out of seven suffers from true impulse control disorders such as pathological gambling, hypersexuality, compulsive shopping and binge eating. Dopaminergic drugs used in anti-Parkinson therapy, especially dopamine agonists, increase the risk of these disorders. Impulse control disorders are associated with a relatively more active dopamine-mediated neurotransmission of the mesolimbic and mesocortical system. Discontinuation of dopamine agonist medication can thus be considered as the first line treatment of these disorders. PMID:24397147

  5. Micropower impulse radar technology and applications

    SciTech Connect

    Mast, J., LLNL

    1998-04-15

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

  6. Reward drive and rash impulsiveness as dimensions of impulsivity: implications for substance misuse.

    PubMed

    Dawe, Sharon; Gullo, Matthew J; Loxton, Natalie J

    2004-09-01

    One of the primary personality dimensions or traits that has consistently been linked to substance abuse is impulsivity. However, impulsivity is not a homogenous construct and although many of the measures of impulsivity are correlated, the most recent review of published factor analytic studies has proposed two independent dimensions of impulsivity: reward sensitivity, reflecting one of the primary dimension of J. A. Gray's personality theory, and rash impulsiveness. These two facets of impulsivity derived from the field of personality research parallel recent developments in the neurosciences where changes in the incentive value of rewarding substances has been linked to alterations in neural substrates involved in reward seeking and with a diminished capacity to inhibit behavior due to chronic drug exposure. In this paper, we propose a model that integrates the findings from research into individual differences with recent models of neural substrates implicated in the development of substance misuse.

  7. Impulsively generated fast coronal pulsations

    NASA Technical Reports Server (NTRS)

    Edwin, P. M.; Roberts, B.

    1986-01-01

    Rapid oscillations in the corona are discussed from a theoretical standpoint, developing some previous work on ducted, fast magnetoacoustic waves in an inhomogeneous medium. In the theory, impulsively (e.g., flare) generated mhd (magnetohydrodynamic) waves are ducted by regions of low Alfven speed (high density) such as coronal loops. Wave propagation in such ducts is strongly dispersive and closely akin to the behavior of Love waves in seismology, Pekeris waves in oceanography and guided waves in fiber optics. Such flare-generated magnetoacoustic waves possess distinctive temporal signatures consisting of periodic, quasi-periodic and decay phases. The quasi-periodic phase possesses the strongest amplitudes and the shortest time scales. Time scales are typically of the order of a second for inhomogeneities (coronal loop width) of 1000 km and Alfven speeds of 1000/kms, and pulse duration times are of tens of seconds. Quasi-periodic signatures have been observed in radio wavelengths for over a decade and more recently by SMM. It is hoped that the theoretical ideas outlined may be successfully related to these observations and thus aid the interpretation of oscillatory signatures recorded by SMM. Such signatures may also provide a diagnostic of coronal conditions. New aspects of the ducted mhd waves, for example their behavior in smoothly varying as opposed to tube-like inhomogeneities, are currently under investigation. The theory is not restricted to loops but applied equally to open field regions.

  8. Specific Impulse Definition for Ablative Laser Propulsion

    NASA Astrophysics Data System (ADS)

    Gregory, Don A.; Herren, Kenneth A.

    2005-04-01

    The term "specific impulse" is so ingrained in the field of rocket propulsion that it is unlikely that any fundamental argument would be taken seriously for its removal. It is not an ideal measure but it does give an indication of the amount of mass flow (mass loss/time), as in fuel rate, required to produce a measured thrust over some time period. This investigation explores the implications of being able to accurately measure the ablation rate and how the language used to describe the specific impulse results may have to change slightly, and recasts the specific impulse as something that is not a time average. It is not currently possible to measure the ablation rate accurately in real time so it is generally just assumed that a constant amount of material will be removed for each laser pulse delivered. The specific impulse dependence on the ablation rate is determined here as a correction to the classical textbook definition.

  9. Behavioral Measures of Impulsivity and the Law

    PubMed Central

    Mathias, Charles W.; Marsh-Richard, Dawn M.; Dougherty, Donald M.

    2012-01-01

    The General Theory of Crime proposes that crime is explained by the combination of situational opportunity and lack of self-control. Impulsivity is one of the important components of self-control. Because behavioral measures of impulsivity are becoming more commonly utilized to assess forensic populations, this manuscript provides an overview of three current behavioral measures. In doing so, an example of their application is provided using a group of individuals likely to come into contact with the legal system: adolescents with Conduct Disorder. Earlier age of onset of Conduct Disorder symptoms has been shown to be an important predictor of the persistence of poor outcomes into adulthood including participation in criminal activities. This study found differential behavioral profiles across distinct measures of impulsivity by those with childhood- versus adolescent-onset Conduct Disorder. Legal implications for defining behavioral deficits using behavioral measures of impulsivity and their current limitations are discussed. PMID:19039792

  10. Specific Impulse Definition for Ablative Laser Propulsion

    NASA Technical Reports Server (NTRS)

    Herren, Kenneth A.; Gregory, Don A.

    2004-01-01

    The term "specific impulse" is so ingrained in the field of rocket propulsion that it is unlikely that any fundamental argument would be taken seriously for its removal. It is not an ideal measure but it does give an indication of the amount of mass flow (mass loss/time), as in fuel rate, required to produce a measured thrust over some time period This investigation explores the implications of being able to accurately measure the ablation rate and how the language used to describe the specific impulse results may have to change slightly, and recasts the specific impulse as something that is not a time average. It is not currently possible to measure the ablation rate accurately in real time so it is generally just assumed that a constant amount of material will be removed for each laser pulse delivered The specific impulse dependence on the ablation rate is determined here as a correction to the classical textbook definition.

  11. 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.

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

    PubMed Central

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

    2014-01-01

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

  13. Numerical vorticity creation based on impulse conservation.

    PubMed Central

    Summers, D M; Chorin, A J

    1996-01-01

    The problem of creating solenoidal vortex elements to satisfy no-slip boundary conditions in Lagrangian numerical vortex methods is solved through the use of impulse elements at walls and their subsequent conversion to vortex loops. The algorithm is not uniquely defined, due to the gauge freedom in the definition of impulse; the numerically optimal choice of gauge remains to be determined. Two different choices are discussed, and an application to flow past a sphere is sketched. PMID:11607636

  14. 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.

  15. Distinct facets of impulsivity exhibit differential associations with substance use disorder treatment processes: a cross-sectional and prospective investigation among military veterans.

    PubMed

    Heinz, Adrienne J; Bui, Leena; Thomas, Katherine M; Blonigen, Daniel M

    2015-08-01

    Impulsivity, a multi-faceted construct characterized by rash, unplanned actions and a disregard for long-term consequences, is associated with poor substance use disorder (SUD) treatment outcomes. Little is known though about the influence of impulsivity on treatment process variables critical for initiating and maintaining behavioral change. This knowledge gap is important as different aspects of impulsivity may be susceptible to diverse cognitive, behavioral and pharmacological influences. The present study examined two distinct facets of impulsivity (lack of planning and immoderation--a proxy of urgency) as predictors of processes that impact SUD treatment success (active coping, avoidant coping, self-efficacy, and interpersonal problems). Participants were 200 Veterans who completed impulsivity and treatment process assessments upon entering an SUD treatment program and treatment process assessments at treatment discharge. Results from multivariate models revealed that lack of planning was associated with lower active coping and higher avoidant coping and interpersonal problems at intake, though not with lower self-efficacy to abstain from substances. Immoderation was associated with higher avoidant coping and lower self-efficacy to abstain from substances at intake, but not with lower active coping or higher interpersonal problems. Higher immoderation, but not lack of planning, predicted lower self-efficacy to abstain from substances at treatment discharge. These findings suggest that different facets of impulsivity confer risk for different SUD treatment process indicators and that clinicians should consider the behavioral expression of patients' impulse control problems in treatment planning and delivery.

  16. Distinct Facets of Impulsivity Exhibit Differential Associations with Substance Use Disorder Treatment Processes: A Cross-Sectional and Prospective Investigation Among Military Veterans

    PubMed Central

    Heinz, Adrienne J.; Bui, Leena; Thomas, Katherine M.; Blonigen, Daniel M.

    2015-01-01

    Impulsivity, a multi-faceted construct characterized by rash, unplanned actions and a disregard for long-term consequences, is associated with poor substance use disorder (SUD) treatment outcomes. Little is known though about the influence of impulsivity on treatment process variables critical for initiating and maintaining behavioral change. This knowledge gap is important as different aspects of impulsivity may be susceptible to diverse cognitive, behavioral and pharmacological influences. The present study examined two distinct facets of impulsivity (lack of planning and immoderation - a proxy of urgency) as predictors of processes that impact SUD treatment success (active coping, avoidant coping, self-efficacy, and interpersonal problems). Participants were 200 Veterans who completed impulsivity and treatment process assessments upon entering a SUD treatment program and treatment process assessments at treatment discharge. Results from multivariate models revealed that lack of planning was associated with lower active coping and higher avoidant coping and interpersonal problems at intake, though not with lower self-efficacy to abstain from substances. Immoderation was associated with higher avoidant coping and lower self-efficacy to abstain from substances at intake, but not with lower active coping or higher interpersonal problems. Higher immoderation, but not lack of planning, predicted lower self-efficacy to abstain from substances at treatment discharge. These findings suggest that different facets of impulsivity confer risk for different SUD treatment process indicators and that clinicians should consider the behavioral expression of patients’ impulse control problems in treatment planning and delivery. PMID:25770869

  17. Generalized transfers and the nonoptimality of purely radial impulses

    NASA Astrophysics Data System (ADS)

    Lashkin, V. I.

    1985-07-01

    A system of variables is proposed that is convenient for the precise formulation of the problem of optimal multiple-impulse transfer between arbitrary nonrectilinear Kepler orbits. The existence of a universal two-impulse transfer with transverse impulses is demonstrated for such orbits. Calculation formulas for these impulses are obtained which generalize the corresponding formulas of two-impulse Hohmann transfer between circular orbits. In addition, a lower-bound estimate is obtained for the characteristic velocity of a one-impulse transfer between orbits having a common point, and the nonoptimality of an arbitrary radial impulse is demonstrated.

  18. Enhanced awakening probability of repetitive impulse sounds.

    PubMed

    Vos, Joos; Houben, Mark M J

    2013-09-01

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

  19. 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.

  20. 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. PMID:1842469

  1. Identifying Groundwater Discharge Sources and Associated Geochemical Influences Using Resistivity Imaging and Geochemical Tracers in a Semi-Arid Estuary in South Texas

    NASA Astrophysics Data System (ADS)

    Douglas, A. R.; Murgulet, D.; Spalt, N.

    2015-12-01

    The Nueces Bay (NB) system has been found to be ecologically unsound due to the loss/alteration of habitat and flow regimes required by indicator species and compromised nutrient cycling and sediment loading. The management practices of freshwater inflow regimes to NB concentrates on surface water flows and does not account for groundwater inflows, though submarine groundwater discharge (SGD) has been identified as a source of freshwater and limiting nutrients that could significantly impact bay salinities and nutrient loading. To encompass the range of spatio-temporal variabilities occurring between groundwater (GW) and surface-water (SW), multiple methods, including resistivity imaging, geochemical tracers, and radioisotopes, are applied in conjunction to identify SGD sources. Preliminary continuous resistivity profile surveys identified multiple possible GW upwelling paths from which thirteen stations were chosen in NB and two stations in Nueces River (NR). A Principal Component Analysis (PCA) of initial geochemical, nutrient and radioisotope data, shows that 76% of the variation in the data is explained by three factors: seasonality, freshwater inflows, and reducing environment. Significant seasonal variation is seen in average SW salinity (37psu in September 2014 to 4psu in June 2015), Ra-224 (359dpm/L in September to 636dpm/L in December), Ra-226 (268dpm/L in September to 570 dpm/L in December), ammonium (1.3μM in September to 5.5μM in April), and chlorophyll-α (3.99μg/L in December to 12.3 μg/L in April). Additionally, short-lived radioisotopes Rn-222 and Ra-224 are consistently elevated near the NR mouth, the inflow from Gum Hollow Creek, and a single station in the middle of the Bay indicating more localized, active SGD sources. However, only the stations in NR and at the NR mouth show consistently strong correlations to chlorophyll-α, phosphate, and silicate, with the river station closest to NB having the highest concentrations of nitrogen

  2. Refinement and application of acoustic impulse technique to study nozzle transmission characteristics

    NASA Technical Reports Server (NTRS)

    Salikuddin, M.; Brown, W. H.; Ramakrishnan, R.; Tanna, H. K.

    1983-01-01

    An improved acoustic impulse technique was developed and was used to study the transmission characteristics of duct/nozzle systems. To accomplish the above objective, various problems associated with the existing spark-discharge impulse technique were first studied. These included (1) the nonlinear behavior of high intensity pulses, (2) the contamination of the signal with flow noise, (3) low signal-to-noise ratio at high exhaust velocities, and (4) the inability to control or shape the signal generated by the source, specially when multiple spark points were used as the source. The first step to resolve these problems was the replacement of the spark-discharge source with electroacoustic driver(s). These included (1) synthesizing on acoustic impulse with acoustic driver(s) to control and shape the output signal, (2) time domain signal averaging to remove flow noise from the contaminated signal, (3) signal editing to remove unwanted portions of the time history, (4) spectral averaging, and (5) numerical smoothing. The acoustic power measurement technique was improved by taking multiple induct measurements and by a modal decomposition process to account for the contribution of higher order modes in the power computation. The improved acoustic impulse technique was then validated by comparing the results derived by an impedance tube method. The mechanism of acoustic power loss, that occurs when sound is transmitted through nozzle terminations, was investigated. Finally, the refined impulse technique was applied to obtain more accurate results for the acoustic transmission characteristics of a conical nozzle and a multi-lobe multi-tube supressor nozzle.

  3. Asthma - child - discharge

    MedlinePlus

    Pediatric asthma - discharge; Wheezing - discharge; Reactive airway disease - discharge ... Your child has asthma , which causes the airways of the lungs to swell and narrow. In the hospital, the doctors and nurses helped ...

  4. Tubal ligation - discharge

    MedlinePlus

    ... Tubal sterilization - discharge; Tube tying - discharge; Tying the tubes - discharge; Contraception - tubal ... You had tubal ligation (or tying the tubes) surgery to close your fallopian tubes. These tubes connect the ovaries to the uterus. After tubal ...

  5. Concussion - child - discharge

    MedlinePlus

    ... discharge; Mild traumatic brain injury - child - discharge; Closed head injury - child - discharge ... mild brain injury that can result when the head hits an object or a moving object strikes ...

  6. Laparoscopic gastric banding - discharge

    MedlinePlus

    ... laparoscopic gastric banding - discharge; Obesity gastric banding discharge; Weight loss - gastric banding discharge ... as your body gets used to your weight loss and your weight becomes stable. Weight loss may be slower after ...

  7. Tennis elbow surgery - discharge

    MedlinePlus

    Lateral epicondylitis surgery - discharge; Lateral tendinosis surgery - discharge; Lateral tennis elbow surgery - discharge ... Soon after surgery, severe pain will decrease, but you may have mild soreness for 3 to 6 months.

  8. Concussion - adults - discharge

    MedlinePlus

    Brain injury - concussion - discharge; Traumatic brain injury - concussion - discharge; Closed head injury - concussion - discharge ... Play contact sports, such as football, hockey, and soccer Ride a bicycle, motorcycle, or off-road vehicle ...

  9. A computational investigation of impulsive and pulsed starting annular jets

    NASA Astrophysics Data System (ADS)

    Abdel-Raouf, Emad Mohamed Refaat

    2011-12-01

    A computational study is carried out on low Reynolds number impulsive and pulsating annular jets. This work is inspired by the biological flow of marine life that uses jet propulsion for self maneuver. Marine life such as squids and jellyfish propel themselves by discharging a water jet followed by a refilling phase. The discharging portion is a starting jet, i.e. the releasing of a moving fluid into a quiescent fluid, while the refilling phase can be viewed as an inflow jet. The combined jets will be called fully oscillating jets. Although fully oscillating jets have been indirectly examined experimentally, they have never been studied computationally. This dissertation is divided into three investigations that examine the starting jet, inflow jet, and fully oscillating jet based on the resultant force (i.e. either thrust or suction force) at the annulus exit plane, jet efficiency, and vortex dynamics. Furthermore, each of the following three performance criterion is examined under various velocity imposed boundaries (i.e. impulsive, unit pulsed, and sinusoidal pulsed jets), ambient pressure, and blocking ratios. An axisymmetric, incompressible and unsteady Navier Stokes numerical model was used to implement the analysis. The model was validated against theoretical and experimental results, where both result types bounded the computational results of this endeavor. In addition, numerical verification was carried out on each of the three investigations ensuring grid and time independent results. Several substantial outcomes were drawn from the results of the three investigations. The numerical results confirmed previously published experimental data regarding the universal dimensionless time scale (i.e. vortex formation number) of optimal vortex ring development triggered by starting jets. Moreover, the computational results showed evidence that the vortex formation number was not affected by ambient pressure nor blocking ratio. The computational results also

  10. [Impulsivity and compulsivity in cocaine dependent individuals].

    PubMed

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

    2012-01-01

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

  11. Transition Region and Chromospheric Signatures of Impulsive Heating Events. I. Observations

    NASA Astrophysics Data System (ADS)

    Warren, Harry P.; Reep, Jeffrey W.; Crump, Nicholas A.; Simões, Paulo J. A.

    2016-09-01

    We exploit the high spatial resolution and high cadence of the Interface Region Imaging Spectrograph (IRIS) to investigate the response of the transition region and chromosphere to energy deposition during a small flare. Simultaneous observations from the Reuven Ramaty High Energy Solar Spectroscopic Imager provide constraints on the energetic electrons precipitating into the flare footpoints, while observations of the X-Ray Telescope, Atmospheric Imaging Assembly, and Extreme Ultraviolet Imaging Spectrometer (EIS) allow us to measure the temperatures and emission measures from the resulting flare loops. We find clear evidence for heating over an extended period on the spatial scale of a single IRIS pixel. During the impulsive phase of this event, the intensities in each pixel for the Si iv 1402.770 Å, C ii 1334.535 Å, Mg ii 2796.354 Å, and O i 1355.598 Å emission lines are characterized by numerous small-scale bursts typically lasting 60 s or less. Redshifts are observed in Si iv, C ii, and Mg ii during the impulsive phase. Mg ii shows redshifts during the bursts and stationary emission at other times. The Si iv and C ii profiles, in contrast, are observed to be redshifted at all times during the impulsive phase. These persistent redshifts are a challenge for one-dimensional hydrodynamic models, which predict only short-duration downflows in response to impulsive heating. We conjecture that energy is being released on many small-scale filaments with a power-law distribution of heating rates.

  12. Magnetic dipole discharges. I. Basic properties

    SciTech Connect

    Stenzel, R. L.; Urrutia, J. M.; Teodorescu-Soare, C. T.; Ionita, C.; Schrittwieser, R.

    2013-08-15

    A simple discharge is described which uses a permanent magnet as a cold cathode and the metallic chamber wall as an anode. The magnet's equator is biased strongly negative, which produces secondary electrons due to the impact of energetic ions. The emitted electrons are highly confined by the strong dipolar magnetic field and the negative potential in the equatorial plane of the magnet. The emitted electrons ionize near the sheath and produce further electrons, which drift across field lines to the anode while the nearly unmagnetized ions are accelerated back to the magnet. A steady state discharge is maintained at neutral pressures above 10{sup −3} mbar. This is the principle of magnetron discharges, which commonly use cylindrical and planar cathodes rather than magnetic dipoles as cathodes. The discharge properties have been investigated in steady state and pulsed mode. Different magnets and geometries have been employed. The role of a background plasma has been investigated. Various types of instabilities have been observed such as sheath oscillations, current-driven turbulence, relaxation instabilities due to ionization, and high frequency oscillations created by sputtering impulses, which are described in more detail in companion papers. The discharge has also been operated in reactive gases and shown to be useful for sputtering applications.

  13. A unified impulse response model for DCE-MRI.

    PubMed

    Schabel, Matthias C

    2012-11-01

    We describe the gamma capillary transit time model, a generalized impulse response model for DCE-MRI that mathematically unifies the Tofts-Kety, extended Tofts-Kety, adiabatic tissue homogeneity, and two-compartment exchange models. By including a parameter (α⁻¹) representing the width of the distribution of capillary transit times within a tissue voxel, the GCTT model discriminates tissues having relatively monodisperse transit time distributions from those having a large degree of heterogeneity. All five models were compared using in vivo data acquired in three brain tumors (one glioblastoma multiforme, one pleomorphic xanthoastrocytoma, and one anaplastic meningioma) and Monte Carlo simulations. Our principal findings are : (1) The four most commonly used models for dynamic contrast-enhanced magnetic resonance imaging can be unified within a single formalism. (2) Application of the GCTT model to in vivo data incurs only modest penalties in parameter uncertainty and computational cost. (3) Measured nonparametric impulse response functions in human brain tumors are well described by the GCTT model. (4) Estimation of α⁻¹ is feasible but achieving statistical significance requires higher SNR than is typically obtained in single voxel dynamic contrast-enhanced magnetic resonance imaging data. These results suggest that the GCTT model may be useful for extraction of information about tumor physiology beyond what is obtained using current modeling methodologies.

  14. Solar Flare Impulsive Phase Observations from SDO and Other Observatories

    NASA Technical Reports Server (NTRS)

    Chamberlin, Phillip C.; Woods, Thomas N.; Schrijver, Karel; Warren, Harry; Milligan, Ryan; Christe, Steven; Brosius, Jeffrey W.

    2010-01-01

    With the start of normal operations of the Solar Dynamics Observatory in May 2010, the Extreme ultraviolet Variability Experiment (EVE) and the Atmospheric Imaging Assembly (AIA) have been returning the most accurate solar XUV and EUV measurements every 10 and 12 seconds, respectively, at almost 100% duty cycle. The focus of the presentation will be the solar flare impulsive phase observations provided by EVE and AIA and what these observations can tell us about the evolution of the initial phase of solar flares. Also emphasized throughout is how simultaneous observations with other instruments, such as RHESSI, SOHO-CDS, and HINODE-EIS, will help provide a more complete characterization of the solar flares and the evolution and energetics during the impulsive phase. These co-temporal observations from the other solar instruments can provide information such as extending the high temperature range spectra and images beyond that provided by the EUV and XUV wavelengths, provide electron density input into the lower atmosphere at the footpoints, and provide plasma flows of chromospheric evaporation, among other characteristics.

  15. Effects of acoustic impulses on hearing

    NASA Astrophysics Data System (ADS)

    Fleischer, Gerald; Müller, Reinhard; Heppelmann, Guido; Bache, Thomas

    2002-05-01

    It is well known that acoustic impulses are especially dangerous to the ear. In order to understand the damaging mechanisms involved, cases of acute acoustic trauma in man were systematically collected and documented for many years. When possible, the damaging impulses were recreated and measured, to correlate the impulses with the auditory damage they caused. Detailed pure-tone audiometry up to 16 kHz was used to determine the effects on hearing. Together with epidemiological studies on various occupations, three different damaging mechanisms can be discerned. Relatively long and massive impulses (some explosions, some airbags) often lead to damage at low frequencies, from about 0.5 to 1.5 kHz. The typical notch at about 4 to 6 kHz typically is the result of strong peaks, lasting several milliseconds, or longer. There is another notch at 12 to 14 kHz, characteristic of very short, needle-like impulses that are caused by many hand weapons, toy pistols, and firecrackers. Probable mechanisms are discussed.

  16. Impulsivity, Frontal Lobes and Risk for Addiction

    PubMed Central

    Crews, Fulton Timm; Boettiger, Charlotte Ann

    2009-01-01

    Alcohol and substance abuse disorders involve continued use of substances despite negative consequences, i.e. loss of behavioral control of drug use. The frontal cortical areas of brain oversee behavioral control through executive functions. Executive functions include abstract thinking, motivation, planning, attention to tasks and inhibition of impulsive responses. Impulsiveness generally refers to premature, unduly risky, poorly conceived actions. Dysfunctional impulsivity includes deficits in attention, lack of reflection and/or insensitivity to consequences, all of which occur in addiction (Evenden, 1999; (de Wit, 2009). Binge drinking models indicate chronic alcohol damages corticolimbic brain regions (Crews et al., 2000) causing reversal learning deficits indicative of loss of executive function (Obernier et al., 2002b). Genetics and adolescent age are risk factors for alcoholism that coincide with sensitivity to alcohol induced neurotoxicity. Cortical degeneration from alcohol abuse may increase impulsivity contributing to the development, persistence and severity of alcohol use disorders. Interestingly, abstinence results in bursts of neurogenesis and brain regrowth (Crews and Nixon, 2009). Treatments for alcoholism, including naltrexone pharmacotherapy and psychotherapy may work through improving executive functions. This review will examine the relationships between impulsivity and executive function behaviors to changes in cortical structure during alcohol dependence and recovery. PMID:19410598

  17. Relationships Between Impulsivity, Anxiety, and Risk-Taking and the Neural Correlates of Attention in Adolescents.

    PubMed

    Elsey, James W B; Crowley, Michael J; Mencl, W Einar; Lacadie, Cheryl M; Mayes, Linda C; Potenza, Marc N

    2016-01-01

    Although impulsivity, anxiety, and risk-taking may relate to attentional processes, little research has directly investigated how each may be associated with specific facets of attentional processes and their underlying neural correlates. Nineteen adolescents performed a functional magnetic resonance imaging task involving simple, selective, and divided attention. Out-of-scanner-assessed impulsivity, anxiety, and risk-taking scores were not correlated with each other and showed task-phase-specific patterns of association. Results are discussed in light of research and theory suggesting a relationship between these domains and attention and may serve to focus future research aiming to understand these relationships. PMID:27135550

  18. Auto-programmable impulse neural circuits

    NASA Technical Reports Server (NTRS)

    Watula, D.; Meador, J.

    1990-01-01

    Impulse neural networks use pulse trains to communicate neuron activation levels. Impulse neural circuits emulate natural neurons at a more detailed level than that typically employed by contemporary neural network implementation methods. An impulse neural circuit which realizes short term memory dynamics is presented. The operation of that circuit is then characterized in terms of pulse frequency modulated signals. Both fixed and programmable synapse circuits for realizing long term memory are also described. The implementation of a simple and useful unsupervised learning law is then presented. The implementation of a differential Hebbian learning rule for a specific mean-frequency signal interpretation is shown to have a straightforward implementation using digital combinational logic with a variation of a previously developed programmable synapse circuit. This circuit is expected to be exploited for simple and straightforward implementation of future auto-adaptive neural circuits.

  19. An Efficient Adaptive Weighted Switching Median Filter for Removing High Density Impulse Noise

    NASA Astrophysics Data System (ADS)

    Nair, Madhu S.; Ameera Mol, P. M.

    2014-09-01

    Restoration of images corrupted by impulse noise is a very active research area in image processing. In this paper, an Efficient Adaptive Weighted Switching Median filter for restoration of images that are corrupted by high density impulse noise is proposed. The filtering is performed as a two phase process—a detection phase followed by a filtering phase. In the proposed method, noise detection is done by HEIND algorithm proposed by Duan et al. The filtering algorithm is then applied to the pixels which are detected as noisy by the detection algorithm. All uncorrupted pixels in the image are left unchanged. The filtering window size is chosen adaptively depending on the local noise distribution around each corrupted pixels. Noisy pixels are replaced by a weighted median value of uncorrupted pixels in the filtering window. The weight value assigned to each uncorrupted pixels depends on its closeness to the central pixel.

  20. 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. PMID:27186976

  1. Disentangling impulsiveness, aggressiveness and impulsive aggression: an empirical approach using self-report measures.

    PubMed

    García-Forero, Carlos; Gallardo-Pujol, David; Maydeu-Olivares, Alberto; Andrés-Pueyo, Antonio

    2009-06-30

    There is confusion in the literature concerning the concept of impulsive aggression. Based on previous research, we hypothesize that impulsivity and aggression may be related, though not as closely as to consider them the same construct. So, our aim was to provide empirical evidence of the relationship between the impulsivity and aggressiveness constructs when considered as traits. Two widely used questionnaires [Barratt's Impulsiveness Scale (BIS) and Aggression Questionnaire-Refined (AQ-R)] were administered to 768 healthy respondents. Product-moment and canonical correlations were then calculated. In addition, a principal components analysis was conducted to explore whether impulsive aggression can be defined phenotypically as the expression of a single trait. The common variance between impulsivity and aggressiveness was never higher than 42%. The principal components analysis reveals that one component is not enough to represent all the variables. In conclusion, our results show that impulsivity and aggressiveness are two separate, although related constructs. This is particularly important in view of the misconceptions in the literature.

  2. Reaction of communities to impulse noise

    NASA Astrophysics Data System (ADS)

    Seshagiri, B. V.

    1981-01-01

    In order to assess the reaction of communities to impulse noise, a sociological survey was conducted in three communities in Ontario, Canada. The dominant industrial noise in these locations is due to drop forging operations. Nearly 600 completed interviews were recorded. Detailed sound level measurements were carried out in the areas surveyed. The results clearly indicate the extent of adverse reaction to the forging noise. This research has been compared with the reaction of the respondents to traffic noise prevailing in their communities. Regression lines are presented showing the relationship between the percent of people disturbed by the forging noise and the sound level of the impulses.

  3. Impulsive nonconformity in female chat room users.

    PubMed

    Fullwood, Chris; Galbraith, Niall; Morris, Neil

    2006-10-01

    Heavy chat room use has been associated with social isolation, introversion, impulse control problems, and risk taking. Such characteristics form part of the cluster of traits associated with schizotypy. This study used multiple regression to examine the relationship between age, sex, four dimensions of schizotypy, and frequency of reported chat room use. The only significant association with schizotypy was between frequency of chat room use and impulsive nonconformity (IN) in females. These findings may be explained by the increased risk associated with female chat room use.

  4. International comparison of HV impulse measuring systems

    SciTech Connect

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

    1989-04-01

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

  5. Optimal noncoplanar interorbital single-impulse flight

    NASA Astrophysics Data System (ADS)

    Kirpichnikov, S. N.

    1990-04-01

    The paper is concerned with the problem of finding minimum-fuel orbits for single-impulse transfers between specified noncoplanar boundary Keplerian orbits. In transfers between noncoplanar circular orbits, the Hohmann single-impulse transfer in the initial orbit plane is shown to be globally optimal from the energy standpoint. Approximate optimal solutions are obtained in the practically important case of weakly elliptical boundary orbits with a small angle between the planes. The optimal solutions obtained here can be used as initial approximations when determining real orbits for interorbital and interplanetary flights.

  6. Particle visualization in high-power impulse magnetron sputtering. II. Absolute density dynamics

    SciTech Connect

    Britun, Nikolay Palmucci, Maria; Konstantinidis, Stephanos; Snyders, Rony

    2015-04-28

    Time-resolved characterization of an Ar-Ti high-power impulse magnetron sputtering discharge has been performed. The present, second, paper of the study is related to the discharge characterization in terms of the absolute density of species using resonant absorption spectroscopy. The results on the time-resolved density evolution of the neutral and singly-ionized Ti ground state atoms as well as the metastable Ti and Ar atoms during the discharge on- and off-time are presented. Among the others, the questions related to the inversion of population of the Ti energy sublevels, as well as to re-normalization of the two-dimensional density maps in terms of the absolute density of species, are stressed.

  7. Microscopic mechanism of path-dependence on charge-discharge history in lithium iron phosphate cathode analysis using scanning transmission electron microscopy and electron energy-loss spectroscopy spectral imaging

    NASA Astrophysics Data System (ADS)

    Honda, Yoshitake; Muto, Shunsuke; Tatsumi, Kazuyoshi; Kondo, Hiroki; Horibuchi, Kayo; Kobayashi, Tetsuro; Sasaki, Tsuyoshi

    2015-09-01

    We revisited the "path-dependence" problem, i.e., the differing polarization observed in LiFePO4 cathode charge/discharge curves depending on the electrochemical treatment history of the material. The phase distributions of the active material particles with different charge/discharge histories in the LiFePO4 cathode were investigated through spectral imaging (SI) using scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). The STEM-EELS-SI experiments revealed that LiFePO4 (LFP) and FePO4 (FP) almost always coexist in the individual primary particles of Li0.5FePO4 (50% state of charge (SOC)) electrodes, forming core/shell structures. This is unlike the conventional domino-cascade model, in that LFP-inside/FP-outside is observed in the lithium-extracted Li0.5FePO4 particles, whereas FP-inside/LFP-outside is seen in the lithium-inserted Li0.5FePO4 particles. We examined the particle-size dependence of the core/total volume ratio of each Li0.5FePO4 particle, and the essential features of the path-dependent charge/discharge curves were semi-quantitatively reproduced by a simple static model that considered the ionic conductivity of the shell phase.

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

    PubMed

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

    2013-12-01

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

  9. 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

  10. Out of control: Evidence for anterior insula involvement in motor impulsivity and reactive aggression

    PubMed Central

    Sack, Alexander T.; Lobbestael, Jill; Arntz, Arnoud; Brugman, Suzanne; Schuhmann, Teresa

    2015-01-01

    Inhibiting impulsive reactions while still defending one’s vital resources is paramount to functional self-control and successful development in a social environment. However, this ability of successfully inhibiting, and thus controlling one’s impulsivity, often fails, leading to consequences ranging from motor impulsivity to aggressive reactions following provocation. Although inhibitory failure represents the underlying mechanism, the neurocognition of social aggression and motor response inhibition have traditionally been investigated in separation. Here, we aimed to directly investigate and compare the neural mechanisms underlying the failure of inhibition across those different modalities of self-control. We used functional imaging to reveal the overlap in neural correlates between failed motor response inhibition (measured by a go/no-go task) and reactive aggression (measured by the Taylor aggression paradigm) in healthy males. The core overlap of neural correlates was located in the anterior insula, suggesting common anterior insula involvement in motor impulsivity as well as reactive aggression. This evidence regarding an overarching role of the anterior insula across different modalities of self-control enables an integrative perspective on insula function and a better integration of cognitive, social and emotional factors into a comprehensive model of impulsivity. Furthermore, it can eventually lead to a better understanding of clinical syndromes involving inhibitory deficits. PMID:24837479

  11. The Temporal Impulse Response Function in Infantile Nystagmus

    PubMed Central

    Bedell, Harold E.; Ramamurthy, Mahalakshmi; Patel, Saumil S.; Subramaniam, Shobana; Vu-Yu, Lan-Phuong; Tong, Jianliang

    2008-01-01

    Despite rapid to-and-fro motion of the retinal image that results from their incessant involuntary eye movements, persons with infantile nystagmus (IN) rarely report the perception of motion smear. We performed two experiments to determine if the reduction of perceived motion smear in persons with IN is associated with an increase in the speed of the temporal impulse response. In Experiment 1, increment thresholds were determined for pairs of successively presented flashes of a long horizontal line, presented on a 65 cd/m2 background field. The stimulus-onset asynchrony (SOA) between the first and second flash varied from 5.9 to 234 ms. In experiment 2, temporal contrast sensitivity functions were determined for a 3 cpd horizontal square wave grating that underwent counterphase flicker at temporal frequencies between 1 and 40 Hz. Data were obtained for 2 subjects with predominantly pendular IN and 8 normal observers in Experiment 1 and for 3 subjects with IN and 4 normal observers in Experiment 2. Temporal impulse response functions (TIRFs) were estimated as the impulse response of a linear second-order system that provided the best fit to the increment threshold data in Experiment 1 and to the temporal contrast sensitivity functions in Experiment 2. Estimated TIRFs of the subjects with pendular IN have natural temporal frequencies that are significantly faster than those of normal observers (ca. 13 vs. 9 Hz), indicating an accelerated temporal response to visual stimuli. This increase in response speed is too small to account by itself for the virtual absence of perceived motion smear in subjects with IN, and additional neural mechanisms are considered. PMID:18550143

  12. fMRI investigation of response inhibition, emotion, impulsivity, and clinical high-risk behavior in adolescents

    PubMed Central

    Brown, Matthew R. G.; Benoit, James R. A.; Juhás, Michal; Dametto, Ericson; Tse, Tiffanie T.; MacKay, Marnie; Sen, Bhaskar; Carroll, Alan M.; Hodlevskyy, Oleksandr; Silverstone, Peter H.; Dolcos, Florin; Dursun, Serdar M.; Greenshaw, Andrew J.

    2015-01-01

    High-risk behavior in adolescents is associated with injury, mental health problems, and poor outcomes in later life. Improved understanding of the neurobiology of high-risk behavior and impulsivity shows promise for informing clinical treatment and prevention as well as policy to better address high-risk behavior. We recruited 21 adolescents (age 14–17) with a wide range of high-risk behavior tendencies, including medically high-risk participants recruited from psychiatric clinics. Risk tendencies were assessed using the Adolescent Risk Behavior Screen (ARBS). ARBS risk scores correlated highly (0.78) with impulsivity scores from the Barratt Impulsivity scale (BIS). Participants underwent 4.7 Tesla functional magnetic resonance imaging (fMRI) while performing an emotional Go/NoGo task. This task presented an aversive or neutral distractor image simultaneously with each Go or NoGo stimulus. Risk behavior and impulsivity tendencies exhibited similar but not identical associations with fMRI activation patterns in prefrontal brain regions. We interpret these results as reflecting differences in response inhibition, emotional stimulus processing, and emotion regulation in relation to participant risk behavior tendencies and impulsivity levels. The results are consistent with high impulsivity playing an important role in determining high risk tendencies in this sample containing clinically high-risk adolescents. PMID:26483645

  13. Bright and dark sides of impulsivity: performance of women with high and low trait impulsivity on neuropsychological tasks.

    PubMed

    Perales, Jose C; Verdejo-Garcia, Antonio; Moya, Maribel; Lozano, Oscar; Perez-Garcia, Miguel

    2009-11-01

    We administered a multidimensional measure of trait impulsivity (the UPPS-P impulsivity scale; Cyders et al., 2007) to a nonclinical sample of 155 individuals and selected 32 participants at the two ends of the trait impulsivity continuum: high (HI, n = 15) and low (LI, n = 17) impulsive women. We further tested these extreme groups on neuropsychological measures of motor impulsivity (go/no-go, d2), delay discounting (Now or Later Questionnaire), reflection impulsivity (Matching Familiar Figures Test), self-regulation (Revised-Strategy Application Test), and decision making (Iowa Gambling Task). High-trait-impulsivity women were found to commit more commission errors in the initial stage of the go/no-go task but also to make fewer omission errors in the d2 test than did low-trait-impulsivity women. Both effects can be accounted for by a lower response criterion in impulsive women. On the other hand, measures of delay discounting, reflection impulsivity, self-regulation, and decision making did not yield significant differences between the two groups. This pattern of results supports the idea that trait impulsivity in healthy women is linked to neurocognitive mechanisms involved in response monitoring and inhibition, but not to mechanisms involved in self-regulation or decision making. These findings temper the assumption that impulsivity is the core cause of dysfunctional risky and/or impulsive behavior in psychopathological or neuropsychological profiles. PMID:19358009

  14. Ultrahigh Specific Impulse Nuclear Thermal Propulsion

    SciTech Connect

    Anne Charmeau; Brandon Cunningham; Samim Anghaie

    2009-02-09

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

  15. Impulse noise trauma during army weapon firing.

    PubMed

    Munjal, K R; Singh, V P

    1997-04-01

    A 100 infanty personnel firing modern weapons such as the Anti Tank Guided Missile, 106mm Recoiless Gun (RCL), 84mm Rocket Launcher (RL) and 81mm Mortar were studied for the effect of impulse noise on the ear and the evolution of the Temporary Threshold Shift (TTS), Recovery Time (RT) and Permanent Threshold Shift (PTS) was traced. PMID:23119288

  16. Functional impulsivity and reinforcement sensitivity theory.

    PubMed

    Smillie, Luke D; Jackson, Chris J

    2006-02-01

    In this article, we attempt to integrate Dickman's (1990) descriptive concept of Functional Impulsivity (FI) with Gray's (1970, 1991) Reinforcement Sensitivity Theory (RST). Specifically, we consider that FI bears great conceptual similarity to Gray's concept of reward-reactivity, which is thought to be caused by the combined effects of a Behavioral Activation System (BAS) and Behavioral Inhibition System (BIS). In our first study, we examine the construct validity and structural correlates of FI. Results indicate that FI is related positively to measures of BAS and Extraversion, negatively to measures of BIS and Neuroticism, and is separate from Psychoticism and typical trait Impulsivity, which Dickman calls Dysfunctional Impulsivity (DI). In our second study, we use a go/no-go discrimination task to examine the relationship between FI and response bias under conditions of rewarding and punishing feedback. Results indicate that FI, along with two measures of BAS, predicted the development of a response bias for the rewarded alternative. In comparison, high DI appeared to reflect indifference toward either reward or punishment. We consider how these findings might reconcile the perspectives of Gray and Dickman and help clarify the broader understanding of Impulsivity.

  17. How Many Impulsivities? A Discounting Perspective

    ERIC Educational Resources Information Center

    Green, Leonard; Myerson, Joel

    2013-01-01

    People discount the value of delayed and uncertain outcomes, and how steeply individuals discount is thought to reflect how impulsive they are. From this perspective, steep discounting of delayed outcomes (which fails to maximize long-term welfare) and shallow discounting of probabilistic outcomes (which fails to adequately take risk into account)…

  18. Impulsive Behaviors in Patients With Pathological Buying.

    PubMed

    Zander, Heike; Claes, Laurence; Voth, Eva M; de Zwaan, Martina; Müller, Astrid

    2016-09-01

    Aim To investigate impulsive behaviors in pathological buying (PB). Methods The study included three groups matched for age and gender: treatment seeking outpatients with PB (PB+), treatment seeking psychiatric inpatients without PB (PB-), and a healthy control group (HC). PB was assessed by means of the Compulsive Buying Scale and by the impulse control disorder (ICD) module of the research version of the Structured Clinical Interview for DSM-IV (SCID-ICD). All participants answered questionnaires concerning symptoms of borderline personality disorder, self-harming behaviors, binge eating and symptoms of attention deficit and hyperactivity disorder (ADHD). In addition, comorbid ICDs were assessed using the SCID-ICD. Results The PB+ and PB- groups did not differ with regard to borderline personality disorder or ADHD symptoms, but both groups reported significantly more symptoms than the HC group. Frequencies of self-harming behaviors did not differ between the three groups. Patients with PB were more often diagnosed with any current ICD (excluding PB) compared to those without PB and the HC group (38.7% vs. 12.9% vs. 12.9%, respectively, p=.017). Discussion Our findings confirm prior research suggesting more impulsive behaviors in patients with and without PB compared to healthy controls. The results of the questionnaire-based assessment indicate that outpatients with PB perceive themselves equally impulsive and self-harm as frequently as inpatients without PB; but they seem to suffer more often from an ICD as assessed by means of an interview.

  19. Arbitration between controlled and impulsive choices.

    PubMed

    Economides, M; Guitart-Masip, M; Kurth-Nelson, Z; Dolan, R J

    2015-04-01

    The impulse to act for immediate reward often conflicts with more deliberate evaluations that support long-term benefit. The neural architecture that negotiates this conflict remains unclear. One account proposes a single neural circuit that evaluates both immediate and delayed outcomes, while another outlines separate impulsive and patient systems that compete for behavioral control. Here we designed a task in which a complex payout structure divorces the immediate value of acting from the overall long-term value, within the same outcome modality. Using model-based fMRI in humans, we demonstrate separate neural representations of immediate and long-term values, with the former tracked in the anterior caudate (AC) and the latter in the ventromedial prefrontal cortex (vmPFC). Crucially, when subjects' choices were compatible with long-run consequences, value signals in AC were down-weighted and those in vmPFC were enhanced, while the opposite occurred when choice was impulsive. Thus, our data implicate a trade-off in value representation between AC and vmPFC as underlying controlled versus impulsive choice.

  20. Impulsive Behaviors in Patients With Pathological Buying.

    PubMed

    Zander, Heike; Claes, Laurence; Voth, Eva M; de Zwaan, Martina; Müller, Astrid

    2016-09-01

    Aim To investigate impulsive behaviors in pathological buying (PB). Methods The study included three groups matched for age and gender: treatment seeking outpatients with PB (PB+), treatment seeking psychiatric inpatients without PB (PB-), and a healthy control group (HC). PB was assessed by means of the Compulsive Buying Scale and by the impulse control disorder (ICD) module of the research version of the Structured Clinical Interview for DSM-IV (SCID-ICD). All participants answered questionnaires concerning symptoms of borderline personality disorder, self-harming behaviors, binge eating and symptoms of attention deficit and hyperactivity disorder (ADHD). In addition, comorbid ICDs were assessed using the SCID-ICD. Results The PB+ and PB- groups did not differ with regard to borderline personality disorder or ADHD symptoms, but both groups reported significantly more symptoms than the HC group. Frequencies of self-harming behaviors did not differ between the three groups. Patients with PB were more often diagnosed with any current ICD (excluding PB) compared to those without PB and the HC group (38.7% vs. 12.9% vs. 12.9%, respectively, p=.017). Discussion Our findings confirm prior research suggesting more impulsive behaviors in patients with and without PB compared to healthy controls. The results of the questionnaire-based assessment indicate that outpatients with PB perceive themselves equally impulsive and self-harm as frequently as inpatients without PB; but they seem to suffer more often from an ICD as assessed by means of an interview. PMID:27415604

  1. Designing a Stochastic Adaptive Impulsive Observer for Stochastic Linear and Nonlinear Impulsive Systems

    SciTech Connect

    Ayati, Moosa; Alwan, Mohamad; Liu Xinzhi; Khaloozadeh, Hamid

    2011-11-30

    State observation (estimation) is a very important issue in system analysis and control. This paper develops a new observer called Stochastic Adaptive Impulsive Observer (SAIO) for the state estimation of impulsive systems. The proposed observer is applicable to linear and nonlinear stochastic impulsive systems. In addition, the effect of parametric uncertainty is considered and unknown parameters of the system are estimated by suitable adaptation laws. Impulsive system theory, particularly stochastic Lyapunov-like function, is used to analyze the stability and convergence of the state estimations. The main advantages of the proposed observer are: 1) it gives continuous estimation from discrete time measurements of the system output, and 2) it is useful for state estimation when continuous measurements are impossible or expensive. Simulation results show the effectiveness of the proposed observer and we believe that it has many applications in control and estimation theories.

  2. THE EMISSION MEASURE DISTRIBUTION OF IMPULSIVE PHASE FLARE FOOTPOINTS

    SciTech Connect

    Graham, D. R.; Hannah, I. G.; Fletcher, L.; Milligan, R. O.

    2013-04-10

    The temperature distribution of the emitting plasma is a crucial constraint when studying the heating of solar flare footpoints. However, determining this for impulsive phase footpoints has been difficult in the past due to insufficient spatial resolution to resolve the footpoints from the loop structures, and a lack of spectral and temporal coverage. We use the capabilities of Hinode/Extreme Ultraviolet Imaging Spectrometer to obtain the first emission measure distributions (EMDs) from impulsive phase footpoints in six flares. Observations with good spectral coverage were analyzed using a regularized inversion method to recover the EMDs. We find that the EMDs all share a peak temperature of around 8 MK, with lines formed around this temperature having emission measures (EMs) peaking between 10{sup 28} and 10{sup 29} cm{sup -5}, indicating a substantial presence of plasma at very high temperatures within the footpoints. An EMD gradient of EM(T) {approx} T is found in all events. Previous theoretical work on EM gradients shows this to be consistent with a scenario in which the deposited flare energy directly heats only the top layer of the flare chromosphere, while deeper layers are heated by conduction.

  3. Transition Region Abundance Measurements During Impulsive Heating Events

    NASA Astrophysics Data System (ADS)

    Warren, Harry P.; Brooks, David H.; Doschek, George A.; Feldman, Uri

    2016-06-01

    It is well established that elemental abundances vary in the solar atmosphere and that this variation is organized by first ionization potential (FIP). Previous studies have shown that in the solar corona, low-FIP elements such as Fe, Si, Mg, and Ca, are generally enriched relative to high-FIP elements such as C, N, O, Ar, and Ne. In this paper we report on measurements of plasma composition made during impulsive heating events observed at transition region temperatures with the Extreme Ultraviolet Imaging Spectrometer (EIS) on Hinode. During these events the intensities of O iv, v, and vi emission lines are enhanced relative to emission lines from Mg v, vi, and vii and Si vi and vii, and indicate a composition close to that of the photosphere. Long-lived coronal fan structures, in contrast, show an enrichment of low-FIP elements. We conjecture that the plasma composition is an important signature of the coronal heating process, with impulsive heating leading to the evaporation of unfractionated material from the lower layers of the solar atmosphere and higher-frequency heating leading to long-lived structures and the accumulation of low-FIP elements in the corona.

  4. Tomographic reconstruction of the pulse-echo spatiotemporal impulse response

    NASA Astrophysics Data System (ADS)

    Nguyen, Nghia Q.; Abbey, Craig K.; Yapp, Rebecca D.; Insana, Michael F.

    2010-03-01

    Virtually every area of ultrasonic imaging research requires accurate estimation of the spatiotemporal impulse response of the instrument, and yet accurate measurements are difficult to achieve. The impulse response can also be difficult to predict numerically for a specific device because small unknown perturbations in array properties can generate significant changes in predicted pulse-echo field patterns. A typical measurement for a 1-D array transducer employs a line scatterer oriented perpendicular to the scan plane. Echoes from line scatterers located throughout the field of view constitute estimates of shift-varying line response functions. We propose an inverse-problem approach to the reconstruction of point-spread functions from line-spread functions. A collection of echoes recorded for a range of line-scatterer rotation angles are treated as projections of sound pressure onto the transducer array surface. Although the reconstruction is mathematically equivalent to filtered backprojection, it provides significant advantages with respect to interpolation that confound straightforward implementations. Field II predictions used to model measurements made on commercial systems suggest the reconstruction accuracy is with 0.32% for noiseless echo data. Application of the method to data acquired from a commercial system are evaluated from the perspective of deconvolution.

  5. The flare kernel in the impulsive phase

    NASA Technical Reports Server (NTRS)

    Dejager, C.

    1986-01-01

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

  6. Measuring Impulsivity in Adolescents with Serious Substance and Conduct Problems

    ERIC Educational Resources Information Center

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

    2006-01-01

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

  7. Stability analysis of impulsive functional systems of fractional order

    NASA Astrophysics Data System (ADS)

    Stamova, Ivanka; Stamov, Gani

    2014-03-01

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

  8. Teaching Emotional Intelligence to Impulsive-Aggressive Youth.

    ERIC Educational Resources Information Center

    Henley, Martin; Long, Nicholas J.

    1999-01-01

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

  9. An Exploration of Taiwanese Adolescents' Impulsive Buying Tendency

    ERIC Educational Resources Information Center

    Lin, Chien-Huang; Lin, Hung-Ming

    2005-01-01

    The purpose of this study was to examine via a questionnaire the personal characteristics and impulsive buying tendencies of 15- to 19-year-old Taiwanese adolescents. Results indicated that the impulsive buying was significantly associated with gender, age, and amount of pocket money available. Females indicated more impulsive buying than did…

  10. The Effect of Individual Differences on Adolescents' Impulsive Buying Behavior

    ERIC Educational Resources Information Center

    Lin, Chien-Huang; Chuang, Shin-Chieh

    2005-01-01

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

  11. An enantiomorphic blumlein impulse generator

    SciTech Connect

    Rinehart, L.F.; Buttram, M.T.; Crowe, W.R.; Clark, R.S.; Lundstrom, J.M.; Patterson, P.E.

    1992-01-01

    Working designs exist for 1 GW, 1 kHz ultra-wideband (UWB) sources (e.g. SNIPER). As these generators are pressed to higher peak powers and repetition rates, insulation, energy loss due to stray capacitance, and system efficiency (including power supplies and modulators) become critical issues. The EnantioMorphic (mirror image) BLumlein (EMBL) is a new type of vector inversion transmission line pulser which is designed to alleviate some of these problems. The design goals for EMBL are : >500 kV, {approximately}1 kHz rep-rate and <100 ps risetime in a 50 ohm geometry. In addition to the pulse forming line (PFL), EMBL also requires a high rep-rate modulator, primary switch, and peaking switch which will be described. Empirical design equations for peaking switch performance are included.

  12. An enantiomorphic blumlein impulse generator

    SciTech Connect

    Rinehart, L.F.; Buttram, M.T.; Crowe, W.R.; Clark, R.S.; Lundstrom, J.M.; Patterson, P.E.

    1992-07-01

    Working designs exist for 1 GW, 1 kHz ultra-wideband (UWB) sources (e.g. SNIPER). As these generators are pressed to higher peak powers and repetition rates, insulation, energy loss due to stray capacitance, and system efficiency (including power supplies and modulators) become critical issues. The EnantioMorphic (mirror image) BLumlein (EMBL) is a new type of vector inversion transmission line pulser which is designed to alleviate some of these problems. The design goals for EMBL are : >500 kV, {approximately}1 kHz rep-rate and <100 ps risetime in a 50 ohm geometry. In addition to the pulse forming line (PFL), EMBL also requires a high rep-rate modulator, primary switch, and peaking switch which will be described. Empirical design equations for peaking switch performance are included.

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

    PubMed

    Cohen, Lisa J; Gans, Sniezyna Watras; McGeoch, Pamela G; Poznansky, Olga; Itskovich, Yelena; Murphy, Sean; Klein, Erik; Cullen, Ken; Galynker, Igor I

    2002-01-01

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

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

    PubMed Central

    Riemer, Stefanie; Mills, Daniel; Wright, Hannah

    2014-01-01

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

  15. Attentional blink and impulsiveness: evidence for higher functional impulsivity in non-blinkers compared to blinkers.

    PubMed

    Troche, Stefan J; Rammsayer, Thomas H

    2013-08-01

    The attentional blink (AB) represents a fundamental limit of information processing. About 5-10 % of all subjects, however, do not show the AB. Because of the low base rate of these so-called non-blinkers, studies on mechanisms underlying non-blinkers' absent AB are extremely scant. The few existent studies found non-blinkers to be faster and more efficient in information processing compared to blinkers. A personality trait that has been linked previously to speed and efficiency of information processing as well as to the magnitude of the AB is impulsivity. Therefore, the present study investigated whether 15 non-blinkers and 15 blinkers differed from each other in functional and/or dysfunctional impulsivity. To obtain a better understanding of the underlying processing mechanisms, the P300 component in the event-related potential was recorded during performance on the AB task. Our results indicated higher functional impulsivity in non-blinkers compared to blinkers but no differences between the two groups in dysfunctional impulsivity. As indicated by shorter P300 latency, non-blinkers processed information faster than blinkers after the AB period but slower during the AB period. These speed effects, however, were not associated with functional impulsivity. Thus, impulsivity and speed of information processing appear to represent two rather independent sources for non-blinkers' absent AB.

  16. Discharge analysis and electrical modeling for the development of efficient dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Pal, U. N.; Kumar, M.; Tyagi, M. S.; Meena, B. L.; Khatun, H.; Sharma, A. K.

    2010-02-01

    Dielectric-barrier discharges (DBDs) are characterized by the presence of at least one insulating layer in contact with the discharge between two planar or cylindrical electrodes connected to an AC/pulse power supply. The dielectric layers covering the electrodes act as current limiters and prevent the transition to an arc discharge. DBDs exist usually in filamentary mode, based on the streamer nature of the discharges. The main advantage of this type of electrical discharges is that nonequilibrium and non-thermal plasma conditions can be established at atmospheric pressure. VUV/UV sources based on DBDs are considered as promising alternatives of conventional mercury-based discharge plasmas, producing highly efficient VUV/UV radiation. The experiments have been performed using two coaxial quartz double barrier DBD tubes, which are filled with Xe/Ar at different pressures. A sinusoidal voltage up to 2.4 kV peak with frequencies from 20 to 100 kHz has been applied to the discharge electrodes for the generation of microdischarges. A stable and uniform discharge is produced in the gas gap between the dielectric barrier electrodes. By comparisons of visual images and electrical waveforms, the filamentary discharges for Ar tube while homogeneous discharge for Xe tube at the same conditions have been confirmed. The electrical modeling has been carried out to understand DBD phenomenon in variation of applied voltage waveforms. The simulated discharge characteristics have been validated by the experimental results.

  17. Discharge stabilization studies of CO laser gas mixtures in quasi-steady supersonic flow

    NASA Technical Reports Server (NTRS)

    Srinivasan, G.; Smith, J. A.

    1976-01-01

    Experiments were conducted to study the applicability of a double discharge stabilization scheme in conditions appropriate for high energy CO lasers in supersonic flows. A Ludwieg tube impulse flow facility and a ballasted capacitor bank provided essentially steady flow and discharge conditions (d.c.) for times longer than ten electrode length-flow transit times. Steady, arc-free, volume discharges were produced in a Mach 3 test cavity using an auxiliary discharge to stabilize the main discharge in N2 and He/CO mixture. A signigicant result is the lack of observed plasma E/N changes in response to auxiliary discharge current changes. Also, where glow discharges were obtained, the energy loading achieved was very much less than the threshold level required for laser operation.

  18. Visual perception and corollary discharge.

    PubMed

    Sommer, Marc A; Wurtz, Robert H

    2008-01-01

    Perception depends not only on sensory input but also on the state of the brain receiving that input. A classic example is perception of a stable visual world in spite of the saccadic eye movements that shift the images on the retina. A long-standing hypothesis is that the brain compensates for the disruption of visual input by using advance knowledge of the impending saccade, an internally generated corollary discharge. One possible neuronal mechanism for this compensation has been previously identified in parietal and frontal cortex of monkeys, but the origin of the necessary corollary discharge remained unknown. Here, we consider recent experiments that identified a pathway for a corollary discharge for saccades that extends from the superior colliculus in the midbrain to the frontal eye fields in the cerebral cortex with a relay in the medial dorsal nucleus of the thalamus. We first review the nature of the evidence used to identify a corollary discharge signal in the complexity of the primate brain and show its use for guiding a rapid sequence of eye movements. We then consider two experiments that show this same corollary signal may provide the input to the frontal cortex neurons that alters their activity with saccades in ways that could compensate for the displacements in the visual input produced by saccadic eye movements. The first experiment shows that the corollary discharge signal is spatially and temporally appropriate to produce the alterations in the frontal-cortex neurons. The second shows that this signal is necessary for this alteration because inactivation of the corollary reduces the compensation by frontal-cortex neurons. The identification of this relatively simple circuit specifies the organization of a corollary discharge in the primate brain for the first time and provides a specific example upon which consideration of the roles of corollary activity in other systems and for other functions can be evaluated.

  19. Voltage impulse induced bistable magnetization switching in multiferroic heterostructures

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  20. Alterations in Brain Structure and Functional Connectivity in Alcohol Dependent Patients and Possible Association with Impulsivity

    PubMed Central

    Dong, Yue; Ma, Mengying; Ma, Yi; Dong, Yuru; Niu, Yajuan; Jiang, Yin; Wang, Hong; Wang, Zhiyan; Wu, Liuzhen; Sun, Hongqiang; Cui, Cailian

    2016-01-01

    Background Previous studies have documented that heightened impulsivity likely contributes to the development and maintenance of alcohol use disorders. However, there is still a lack of studies that comprehensively detected the brain changes associated with abnormal impulsivity in alcohol addicts. This study was designed to investigate the alterations in brain structure and functional connectivity associated with abnormal impulsivity in alcohol dependent patients. Methods Brain structural and functional magnetic resonance imaging data as well as impulsive behavior data were collected from 20 alcohol dependent patients and 20 age- and sex-matched healthy controls respectively. Voxel-based morphometry was used to investigate the differences of grey matter volume, and tract-based spatial statistics was used to detect abnormal white matter regions between alcohol dependent patients and healthy controls. The alterations in resting-state functional connectivity in alcohol dependent patients were examined using selected brain areas with gray matter deficits as seed regions. Results Compared with healthy controls, alcohol dependent patients had significantly reduced gray matter volume in the mesocorticolimbic system including the dorsal posterior cingulate cortex, the dorsal anterior cingulate cortex, the medial prefrontal cortex, the orbitofrontal cortex and the putamen, decreased fractional anisotropy in the regions connecting the damaged grey matter areas driven by higher radial diffusivity value in the same areas and decreased resting-state functional connectivity within the reward network. Moreover, the gray matter volume of the left medial prefrontal cortex exhibited negative correlations with various impulse indices. Conclusions These findings suggest that chronic alcohol dependence could cause a complex neural changes linked to abnormal impulsivity. PMID:27575491

  1. Statistical Evidence Suggests that Inattention Drives Hyperactivity/Impulsivity in Attention Deficit-Hyperactivity Disorder

    PubMed Central

    Sokolova, Elena; Groot, Perry; Claassen, Tom; van Hulzen, Kimm J.; Glennon, Jeffrey C.; Franke, Barbara

    2016-01-01

    Background Numerous factor analytic studies consistently support a distinction between two symptom domains of attention-deficit/hyperactivity disorder (ADHD), inattention and hyperactivity/impulsivity. Both dimensions show high internal consistency and moderate to strong correlations with each other. However, it is not clear what drives this strong correlation. The aim of this paper is to address this issue. Method We applied a sophisticated approach for causal discovery on three independent data sets of scores of the two ADHD dimensions in NeuroIMAGE (total N = 675), ADHD-200 (N = 245), and IMpACT (N = 164), assessed by different raters and instruments, and further used information on gender or a genetic risk haplotype. Results In all data sets we found strong statistical evidence for the same pattern: the clear dependence between hyperactivity/impulsivity symptom level and an established genetic factor (either gender or risk haplotype) vanishes when one conditions upon inattention symptom level. Under reasonable assumptions, e.g., that phenotypes do not cause genotypes, a causal model that is consistent with this pattern contains a causal path from inattention to hyperactivity/impulsivity. Conclusions The robust dependency cancellation observed in three different data sets suggests that inattention is a driving factor for hyperactivity/impulsivity. This causal hypothesis can be further validated in intervention studies. Our model suggests that interventions that affect inattention will also have an effect on the level of hyperactivity/impulsivity. On the other hand, interventions that affect hyperactivity/impulsivity would not change the level of inattention. This causal model may explain earlier findings on heritable factors causing ADHD reported in the study of twins with learning difficulties. PMID:27768717

  2. Anti-reflux surgery - children - discharge

    MedlinePlus

    Fundoplication - children - discharge; Nissen fundoplication - children - discharge; Belsey (Mark IV) fundoplication - children - discharge; Toupet fundoplication - children - discharge; Thal fundoplication - ...

  3. Chronic obstructive pulmonary disease - adults - discharge

    MedlinePlus

    ... adults - discharge; Chronic obstructive airways disease - adults - discharge; Chronic obstructive lung disease - adults - discharge; Chronic bronchitis - adults - discharge; Emphysema - adults - ...

  4. A Discretized Method for Deriving Vortex Impulse from Volumetric Datasets

    NASA Astrophysics Data System (ADS)

    Buckman, Noam; Mendelson, Leah; Techet, Alexandra

    2015-11-01

    Many biological and mechanical systems transfer momentum through a fluid by creating vortical structures. To study this mechanism, we derive a method for extracting impulse and its time derivative from flow fields observed in experiments and simulations. We begin by discretizing a thin-cored vortex filament, and extend the model to account for finite vortex core thickness and asymmetric distributions of vorticity. By solely using velocity fields to extract vortex cores and calculate circulation, this method is applicable to 3D PIV datasets, even with low spatial resolution flow fields and measurement noise. To assess the performance of this analysis method, we simulate vortex rings and arbitrary vortex structures using OpenFOAM computational fluid dynamics software and analyze the wake momentum using this model in order to validate this method. We further examine a piston-vortex experiment, using 3D synthetic particle image velocimetry (SAPIV) to capture velocity fields. Strengths, limitations, and improvements to the framework are discussed.

  5. Plasma reactivity in high-power impulse magnetron sputtering through oxygen kinetics

    SciTech Connect

    Vitelaru, Catalin; Lundin, Daniel; Brenning, Nils; Minea, Tiberiu

    2013-09-02

    The atomic oxygen metastable dynamics in a Reactive High-Power Impulse Magnetron Sputtering (R-HiPIMS) discharge has been characterized using time-resolved diode laser absorption in an Ar/O{sub 2} gas mixture with a Ti target. Two plasma regions are identified: the ionization region (IR) close to the target and further out the diffusion region (DR), separated by a transition region. The μs temporal resolution allows identifying the main atomic oxygen production and destruction routes, which are found to be very different during the pulse as compared to the afterglow as deduced from their evolution in space and time.

  6. Different subtypes of impulsivity differentiate uncontrolled eating and dietary restraint.

    PubMed

    Leitch, Margaret A; Morgan, Michael J; Yeomans, Martin R

    2013-10-01

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

  7. Narcissism predicts impulsive buying: phenotypic and genetic evidence

    PubMed Central

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

    2015-01-01

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

  8. Narcissism predicts impulsive buying: phenotypic and genetic evidence.

    PubMed

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

    2015-01-01

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

  9. Narcissism predicts impulsive buying: phenotypic and genetic evidence.

    PubMed

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

    2015-01-01

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

  10. Relative rates of growth of annoyance of impulsive and non-impulsive noises.

    PubMed

    Fidell, Sanford; Silvati, Laura; Pearsons, Karl

    2002-01-01

    Twenty-nine people judged the relative annoyance of five variable level signals and 29 impulsive and non-impulsive fixed-level signals in an adaptive paired comparison study. Signals were presented for judgment as heard indoors in a facility capable of accurately reproducing the very low-frequency content of sonic booms. When the annoyance of sonic booms unaccompanied by rattle was compared with that of sounds containing more higher-frequency energy (an aircraft flyover and an octave band of noise centered at 1 kHz), the relative rate of growth of annoyance, as expressed in C-weighted SEL units, was nearly 2:1. In other words, to maintain subjective equality of annoyance, each increase in level of sonic booms had to be matched by nearly twice the increase in level of an aircraft flyover or an octave band of noise centered at 1 kHz. Relative rates of growth of annoyance of sonic booms accompanied by rattle and of non-impulsive sounds, including both low- (63-Hz octave band of noise) and high-frequency energy (1-kHz octave band of noise and an aircraft flyover), were closer to 1:1. Relative rates of growth of annoyance for sonic booms unaccompanied by rattle and low-frequency sounds (63 Hz) were also about 1:1. These differences in relative rates of growth of annoyance of impulsive and non-impulsive sounds are as plausibly attributed to their relative low-frequency content as to impulsiveness per se. It may therefore be more useful for some purposes to express the annoyance of impulsive signals and other environmental noises containing substantial low-frequency energy in terms of effective (duration-corrected) loudness level rather than commonplace ASEL or CSEL. PMID:11837963

  11. Multidimensional Examination of Impulsivity in Relation to Disordered Gambling

    PubMed Central

    MacKillop, James; Miller, Joshua D.; Fortune, Erica; Maples, Jessica; Lance, Charles E.; Campbell, W. Keith; Goodie, Adam S.

    2014-01-01

    Impulsivity has been consistently associated with pathological gambling (PG), but the diversity of definitions and measures of impulsivity has led to ambiguity with regard to which indices are independently relevant. Toward clarifying this relationship, the current study examined indices from an array of commonly-used impulsivity measures in relation to PG severity in an adult community sample of frequent gamblers (N = 353). These included both survey assessments and behavioral tasks. Using a factor analytic approach, four latent factors were identified among 19 indices and were designated reward sensitivity, punishment sensitivity, delay discounting, and cognitive impulsivity. All four latent variables were positively and independently related to PG severity, albeit at a trend level for cognitive impulsivity in a combined model. These findings reveal four generally independent domains of impulsivity that are related to PG severity, clarify which assessment measures aggregate in each domain, and illustrate the importance of measurement specificity in studying impulsivity in relation to PG and other psychiatric disorders. PMID:24708148

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

    PubMed

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

    2014-04-01

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

  13. 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.

  14. Adaptive impulsive cluster synchronization in community network with nonidentical nodes

    NASA Astrophysics Data System (ADS)

    Gong, Xiaoli; Gan, Luyining; Wu, Zhaoyan

    2016-07-01

    In this paper, cluster synchronization in community network with nonidentical nodes is investigated. Through introducing proper adaptive strategy into impulsive control scheme, adaptive impulsive controllers are designed for achieving the cluster synchronization. In this adaptive impulsive control scheme, for any given networks, the impulsive gains can adjust themselves to proper values according to the proposed adaptive strategy when the impulsive intervals are fixed. The impulsive instants can be estimated by solving a sequence of maximum value problems when the impulsive gains are fixed. Both community networks without and with coupling delay are considered. Based on the Lyapunov function method and mathematical analysis technique, two synchronization criteria are derived. Several numerical examples are performed to verify the effectiveness of the derived theoretical results.

  15. Impulsivity/sociability and reinforcement in verbal operant conditioning.

    PubMed

    Gupta, B S; Nagpal, M

    1978-05-01

    The present investigation was designed to study the relationship between impulsivity/sociability and modes of reinforcement in verbal operant conditioning. Two 2x3 randomized block designs, one each for impulsivity and sociability, were replicated ten times. One hundred and twenty undergraduate female students (60 for impulsivity and 60 for sociability) were individually subjected to Taffel's verbal conditioning procedure. When the conditioning scores of high and low scorers on the impulsivity and sociability scales were compared, it was found that under rewarding conditions ('good' and 'buzzer' in respect of sociability and 'good' in respect of impulsivity) the high scorers' score and under punishing conditions ('electric shock') the low scorers' score was the higher of the two. The study also revealed that the high scorers (on the impulsivity scale) conditioned more under rewarding conditions while the low scorers (both on the impulsivity and sociability scales) conditioned more under punishing ones.

  16. Characterisation of pulsed discharge in water

    NASA Astrophysics Data System (ADS)

    Kocik, Marek; Dors, Miroslaw; Podlinski, Janusz; Mizeraczyk, Jerzy; Kanazawa, Seiji; Ichiki, Ryuta; Sato, Takehiko

    2013-10-01

    In this paper, Schlieren photography technique has been applied for the visualization of the pressure field of a single-shot underwater pulsed discharge. A needle-to-plane electrode configuration submerged in distilled water was used. The detailed time- and space-resolved images of both streamers and pressure waves were captured. As a result, several phenomena, such as the phase change prior to the initiation of the discharge, primary and secondary streamers propagation, shock wave generation, and the bubble formation, were observed. From these observations, a scenario of multiple events from prebreakdown to post-discharge was proposed. The gas bubbles generated in discharge were used to visualize the electrohydrodynamic flow induced by the discharge. This work was presented on the occasion of the 13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII).

  17. Carburetor fuel discharge assembly

    SciTech Connect

    Yost, R.M.

    1993-06-29

    An improved carburetor for use on an internal combustion engine is described, the carburetor having an airflow passage and fuel discharge means for admitting fuel into the airflow passage for mixing the fuel with air flowing in the airflow passage to form a fuel/air mixture to be supplied to the combustion chamber(s) of the engine, the fuel discharge means including a fuel discharge assembly which comprises a hollow discharge tube and fuel supplying means connected to the discharge tube for admitting fuel into the interior of the discharge tube, wherein the discharge tube has a longitudinal internal bore in fluid communication with the fuel supplying means, wherein the internal bore extends between an inlet that is closest to the fuel supplying means and an outlet that is furthest from the fuel supplying means with the outlet of the bore being located within the airflow passage of the carburetor to supply fuel into this passage after the fuel passes from the fuel supplying means through the internal bore of the discharge tube, wherein the improvement relates to the fuel discharge assembly and comprises: a hollow fuel flow guide tube telescopically received inside the internal bore of the discharge tube, wherein the fuel flow guide tube extends from approximately the location of the inlet of the bore up at least a portion of the length of the bore towards the outlet of the bore to conduct fuel from the fuel supplying means into the bore of the discharge tube.

  18. A review of impulsive phase phenomena

    NASA Technical Reports Server (NTRS)

    Dejager, C.

    1986-01-01

    A brief review is given of impulsive phase phenomena in support of the models used to compute the energies of the different components of the flares under study. The observational characteristics of the impulsive phase are discussed as well as the evidence for multi-thermal or non-thermal phenomena. The significance of time delays between hard X-rays and microwaves is discussed in terms of electron beams and Alfven waves, two-step acceleration, and secondary bursts at large distances from the primary source. Observations indicating the occurrence of chromospheric evaporation, coronal explosions, and thermal conduction fronts are reviewed briefly, followed by the gamma ray and neutron results. Finally, a preferred flare scenario and energy source are presented involving the interactions in a complex of magnetic loops with the consequent reconnection and electron acceleration.

  19. A Class of Solvable Impulse Control Problems

    SciTech Connect

    Alvarez, Luis H. R.

    2004-05-15

    We consider a class of stochastic impulse control problems where the controlled process evolves according to a linear, regular, and time homogeneous diffusion. We state a set of easily verifiable sufficient conditions under which the problem is explicitly solvable. We also state an algebraic equation from which the optimal impulse boundary can be determined and, given this threshold, we present the value of the optimal policy interms of the minimal increasing r-excessive mapping for the controlled diffusion. We also consider the comparative static properties of the optimal policy and state a set of typically satisfied conditions under which increased volatility unambiguously increases the value of the optimal policy and expands the continuation region where exercising the irreversible policy is suboptimal. We also illustrate our results explicitly in two models based on geometric Brownian motion.

  20. Elegant impulser developed for flat beam injection

    SciTech Connect

    Wilson, M. J., LLNL

    1998-05-26

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

  1. Pinning impulsive control algorithms for complex network.

    PubMed

    Sun, Wen; Lü, Jinhu; Chen, Shihua; Yu, Xinghuo

    2014-03-01

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

  2. Pinning impulsive control algorithms for complex network

    SciTech Connect

    Sun, Wen; Lü, Jinhu; Chen, Shihua; Yu, Xinghuo

    2014-03-15

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

  3. Globally optimal impulsive transfers via Green's theorem

    NASA Astrophysics Data System (ADS)

    Hazelrigg, G. A., Jr.

    1984-08-01

    For certain classes of trajectories the cost function (characteristic velocity) can be written as a 'quasilinear' function of the change in state. In the case presented, impulsive transfers between coplanar, coaxial orbits with transfer time and angle unrestricted, Green's theorem can be used to determine the optimal transfer between given terminal states. This is done in a manner which places no restrictions on the number of impulses used and leads to globally optimal results. These results are used to show that the Hohmann transfer and the biparabolic transfer provide global minima in their respective regions. The regions in which monoelliptic and biparabolic trajectories are globally optimal are also defined for elliptic terminal states. The results are applicable to the case in which restrictions are placed on the radius of closest approach or greatest recession from the center of the force field.

  4. The Stomach-Derived Hormone Ghrelin Increases Impulsive Behavior

    PubMed Central

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

    2016-01-01

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

  5. The Hydraulic Ram (Or Impulse) Pump

    ERIC Educational Resources Information Center

    Mills, Allan

    2014-01-01

    The hydraulic impulse pump utilizes a fraction of the momentum of a flowing stream to lift a small portion of that water to a higher level. There it may be accumulated in an elevated cistern to provide sufficient water for several families, for the pump works 24 h a day with no additional source of energy. The operation of the pump is described,…

  6. The hydraulic ram (or impulse) pump

    NASA Astrophysics Data System (ADS)

    Mills, Allan

    2014-03-01

    The hydraulic impulse pump utilizes a fraction of the momentum of a flowing stream to lift a small portion of that water to a higher level. There it may be accumulated in an elevated cistern to provide sufficient water for several families, for the pump works 24 h a day with no additional source of energy. The operation of the pump is described, along with a working demonstration model constructed from plastic waste pipe and fittings.

  7. Discharge dynamics of pin-to-plate dielectric barrier discharge at atmospheric pressure

    SciTech Connect

    Sun Liqun; Huang, Xiaojiang; Zhang Jie; Zhang Jing; Shi, J. J.

    2010-11-15

    The discharge dynamics of pin-to-plate dielectric barrier discharge was studied in atmospheric helium at 20 kHz. The discharge was predominately ignited in positive half cycle of applied voltage with sinusoidal waveform. The temporal evolution of the discharge was investigated vertically along the discharge gap and radically on the dielectric surface by time resolved imaging. It is found that a discharge column with a diameter of 2 mm was ignited above the pin electrode and expanded toward a plate electrode. On the dielectric surface with space charge accumulation, plasma disk in terms of plasma ring was formed with radius up to 25 mm. The expansion velocity of plasma ring can reach a hypersonic speed of 3.0 km/s. The ionization wave due to electron diffusion is considered to be the mechanism for plasma ring formation and dynamics.

  8. Impulsivity, Stimulant Abuse, and Dopamine Receptor Signaling.

    PubMed

    London, E D

    2016-01-01

    The nonmedical use of amphetamine-type stimulants is a worldwide problem, with substantial medical and social consequences. Nonetheless, the identification of a pharmacological treatment for amphetamine use disorder remains elusive. Stimulant users exhibit neurochemical evidence of dopamine-system dysfunction as well as impulsive behaviors that may interfere with the success of treatments for their addiction. This review focuses on the potential role of dopaminergic neurotransmission in impulsivity, both in healthy individuals and chronic stimulant users who meet criteria for methamphetamine dependence. Presented are findings related to the potential contributions of signaling through dopamine D1- and D2-type receptors to self-control impulsivity in methamphetamine- dependent users. The information available points to signaling through striatal D2-type dopamine receptors as a potential therapeutic target for stimulant use disorders, but medications that target D2-type dopamine receptors have not been successful in treating stimulant-use disorders, possibly because D2-type receptors are downregulated. Other means to augment D2-type receptor signaling are therefore under consideration, and one promising approach is the addition of exercise training as an adjunct to behavioral treatment for addiction. PMID:27288074

  9. Impulsive Injection for Compressor Stator Separation Control

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    Flow control using impulsive injection from the suction surface of a stator vane has been applied in a low speed axial compressor. Impulsive injection is shown to significantly reduce separation relative to steady injection for vanes that were induced to separate by an increase in vane stagger angle of 4 degrees. Injected flow was applied to the airfoil suction surface using spanwise slots pitched in the streamwise direction. Injection was limited to the near-hub region, from 10 to 36 percent of span, to affect the dominant loss due to hub leakage flow. Actuation was provided externally using high-speed solenoid valves closely coupled to the vane tip. Variations in injected mass, frequency, and duty cycle are explored. The local corrected total pressure loss across the vane at the lower span region was reduced by over 20 percent. Additionally, low momentum fluid migrating from the hub region toward the tip was effectively suppressed resulting in an overall benefit which reduced corrected area averaged loss through the passage by 4 percent. The injection mass fraction used for impulsive actuation was typically less than 0.1 percent of the compressor through flow.

  10. Cognitive impulsivity in specific learning disabilities.

    PubMed

    Donfrancesco, Renato; Mugnaini, Daniele; Dell'Uomo, Andrea

    2005-08-01

    Many studies on cognitive impulsivity in learning disabled children have been criticized for their methodological limitations, and they have not dealt with the different types of learning disability. The aim of this study was to overcome these limitations and to assess if there was a significant cognitive impulsivity in reading disorder and/or spelling disorder by using the 20-item Matching Familiar Figures Test (MFF20). A total of 110 children (second through eighth grades) were recruited from a cohort of children assessed for the first time in a National Health clinic specialized in the study of specific learning disabilities. In all, 30 dyslexic children and 25 children with spelling disorder (all children without an ADHD comorbidity) were compared with 55 children of a control group on the MMF20 (accuracy and time latency). Results showed that the children with reading disorder were less accurate than the children with spelling disability (p<0.05). Both these groups performed less accurately than the control group. Subjects with dyslexia were faster than both the other groups in response time (p<0.05), clearly showing a significantly higher cognitive impulsivity than the other groups. Hence, data seem to confirm the idea that, similar to ADHD children, dyslexic children have impaired frontal/prefrontal functions. Clinical and treatment implications are discussed. PMID:15981139

  11. Impulsive Reconnection in the Sun's Atmosphere

    NASA Technical Reports Server (NTRS)

    Antiochos, Spiro K.

    2009-01-01

    Recent high-resolution observations from the Hinode mission show dramatically that the Sun's atmosphere is filled with explosive activity ranging from chromospheric explosions that reach heights of Mm, to coronal jets that can extend to solar radii, to giant coronal mass ejections (CME) that reach the edge of the heliosphere. The driver for all this activity is believed to be 3D magnetic reconnection. From the large variation observed in the temporal behavior of solar activity, it is clear that reconnection in the corona must take on a variety of distinct forms. The explosive nature of jets and CMEs requires that the reconnection be impulsive in that it stays off until a substantial store of free energy has been accumulated, but then turns on abruptly and stays on until much of this free energy is released. The key question, therefore, is what determines whether the reconnection is impulsive or not. We present some of the latest observations and numerical models of explosive and non-explosive solar activity. We argue that, in order for the reconnection to be impulsive, it must be driven by a quasi-ideal instability. We discuss the generality of our results for understanding 31) reconnection in other contexts.

  12. Impulse noise generated by starter pistols

    PubMed Central

    Meinke, Deanna K.; Finan, Donald S.; Soendergaard, Jacob; Flamme, Gregory A.; Murphy, William J.; Lankford, James E.; Stewart, Michael

    2015-01-01

    Objective This study describes signals generated by .22 and .32 caliber starter pistols in the context of noise-induced hearing loss risk for sports officials and athletes. Design Acoustic comparison of impulses generated from typical .22 and .32 caliber starter pistols firing blanks were made to impulses generated from comparable firearms firing both blanks and live rounds. Acoustic characteristics are described in terms of directionality and distance from the shooter in a simulated outdoor running track. Metrics include peak sound pressure levels (SPL), A-weighted equivalent 8-hour level (LeqA8), and maximum permissible number of individual shots, or maximum permissible exposures (MPE) for the unprotected ear. Results Starter pistols produce peak SPLs above 140 dB. The numbers of MPEs are as few as five for the .22-caliber starter pistol, and somewhat higher (≤25) for the .32-caliber pistol. Conclusion The impulsive sounds produced by starter pistols correspond to MPE numbers that are unacceptably small for unprotected officials and others in the immediate vicinity of the shooter. At the distances included in this study, the risk to athletes appears to be low (when referencing exposure criteria for adults), but the sound associated with the starter pistol will contribute to the athlete’s overall noise exposure. PMID:23373743

  13. 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. PMID:27208593

  14. Analyses and tests for design of an electro-impulse de-icing system

    NASA Technical Reports Server (NTRS)

    Zumwalt, G. W.; Schrag, R. L.; Bernhart, W. D.; Friedberg, R. A.

    1985-01-01

    De-icing of aircraft by using the electro-magnetic impulse phenomenon was proposed and demonstrated in several European countries. However, it is not available as a developed system due to lack of research on the basic physical mechanisms and necessary design parameters. The de-icing is accomplished by rapidly discharging high voltage capacitors into a wire coil rigidly supported just inside the aircraft skin. Induced eddy currents in the skin create a repulsive force resulting in a hammer-like force which cracks, de-bonds, and expels ice on the skin surface. The promised advantages are very low energy, high reliability of de-icing, and low maintenance. Three years of Electo-Impulse De-icing (EIDI) research is summarized and the analytical studies and results of testing done in the laboratory, in the NASA Icing Research Tunnel, and in flight are presented. If properly designed, EIDI was demonstrated to be an effective and practical ice protection system for small aircraft, turbojet engine inlets, elements of transport aircraft, and shows promise for use on helicopter rotor blades. Included are practical techniques of fabrication of impulse coils and their mountings. The use of EIDI with nonmetallic surface materials is also described.

  15. Impulsivity and Cigarette Craving among Adolescent Daily and Occasional Smokers

    PubMed Central

    Mathew, Amanda R.; Burris, Jessica L.; Froeliger, Brett; Saladin, Michael E.; Carpenter, Matthew J.

    2015-01-01

    Introduction Impulsivity is a multi-dimensional construct that is robustly related to cigarette smoking. While underlying factors that account for this relation are not well understood, craving has been proposed as a central mechanism linking impulsivity to smoking. In order to further refine our understanding of associations between impulsivity and cigarette craving, the current study examined the association between impulsivity and tonic and cue-elicited craving among a sample of adolescent smokers. We expected trait impulsivity would be positively associated with both tonic and cue-elicited craving, and that this relationship would be stronger among daily vs. occasional smokers. Methods 106 smokers (ages 16–20) completed questionnaires and reported their cigarette craving prior to and immediately following presentation of each of three counterbalanced cue types: (a) in vivo smoking, (b) alcohol, and (c) neutral cue. Results Impulsivity was positively associated with tonic craving for daily smokers (β=.38; p=.005), but not occasional smokers (β=.01; p=.95), with a significant impulsivity x smoker group interaction (β=1.31; p=.03). Impulsivity was unrelated to craving following smoking or alcohol cue, regardless of smoker group (all p’s>.16). Conclusions Results suggest a moderated effect in which impulsivity is positively associated with tonic craving for daily smokers, but not occasional smokers. Tonic craving may serve as a mechanism linking impulsivity, smoking persistence, and nicotine dependence among daily smokers. PMID:25665916

  16. Impulsivity, risky behaviors and accidents in alcohol-dependent patients.

    PubMed

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

    2013-03-01

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

  17. Angioplasty and stent placement - peripheral arteries - discharge

    MedlinePlus

    Percutaneous transluminal angioplasty - peripheral artery - discharge; PTA - peripheral artery - discharge; Angioplasty - peripheral artery - discharge; Balloon angioplasty - peripheral artery- discharge; PAD - PTA discharge; PVD - ...

  18. Relationships of impulsiveness and depressive symptoms in alcohol dependence

    PubMed Central

    Jakubczyk, Andrzej; Klimkiewicz, Anna; Topolewska-Wochowska, Aleksandra; Serafin, Piotr; Sadowska-Mazuryk, Joanna; Pupek-Pyzioł, Julia; Brower, Kirk J.; Wojnar, Marcin

    2011-01-01

    Background Depressive symptoms as well as high levels of impulsivity are subjects of special interest in alcohol dependence, as these factors are considered to influence the course of this disorder. However, until now mutual relationships between impulsivity and depression have not been investigated thoroughly in alcohol-dependent patients. Methods By means of the Barratt Impulsiveness Scale (BIS-11) and stop-signal task, levels of impulsivity among 304 alcohol-dependent patients were measured. The stop-signal task was used as a manipulation-free method of estimating the level of behavioral impulsiveness, and the BIS-11 is a self report measure of global as well as cognitive impulsivity. Patients were also asked to complete the Beck Depression Inventory (BDI) and Hopelessness Scale (BHS). The results were analyzed in order to examine relationships between impulsiveness and depressive symptoms. Results Statistical analyses revealed significant associations between impulsiveness and severity of depressive symptoms. Individuals with higher scores on the BDI were more impulsive on the BIS-11, whereas patients with higher scores on the BHS were more impulsive on both the stop-signal task and BIS-11. The strongest correlations were found with the attention impulsivity subscale of BIS-11. Adjusting for other variables, a linear regression analysis revealed that cognitive impulsivity was the strongest predictor of depression severity. Limitations The main limitation of the study is a not fully representative sample, with exclusion of patients with active mood disorders Conclusions The results indicate a strong association between depressive symptoms and impulsivity in alcohol-dependent patients, and suggest an important distinction between hopelessness and other depressive symptoms. PMID:22030134

  19. Observation and numerical modeling of chromospheric evaporation during the impulsive phase of a solar flare

    NASA Astrophysics Data System (ADS)

    Imada, Shinsuke; Murakami, Izumi; Watanabe, Tetsuya

    2015-10-01

    We have studied the chromospheric evaporation flow during the impulsive phase of the flare by using the Hinode/EUV Imaging Spectrometer observation and 1D hydrodynamic numerical simulation coupled to the time-dependent ionization. The observation clearly shows that the strong redshift can be observed at the base of the flaring loop only during the impulsive phase. We performed two different numerical simulations to reproduce the strong downflows in FeXII and FeXV during the impulsive phase. By changing the thermal conduction coefficient, we carried out the numerical calculation of chromospheric evaporation in the thermal conduction dominant regime (conductivity coefficient κ0 = classical value) and the enthalpy flux dominant regime (κ0 = 0.1 × classical value). The chromospheric evaporation calculation in the enthalpy flux dominant regime could reproduce the strong redshift at the base of the flare during the impulsive phase. This result might indicate that the thermal conduction can be strongly suppressed in some cases of flare. We also find that time-dependent ionization effect is important to reproduce the strong downflows in Fe XII and Fe XV.

  20. 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

  1. Observation and numerical modeling of chromospheric evaporation during the impulsive phase of a solar flare

    SciTech Connect

    Imada, Shinsuke; Murakami, Izumi; Watanabe, Tetsuya

    2015-10-15

    We have studied the chromospheric evaporation flow during the impulsive phase of the flare by using the Hinode/EUV Imaging Spectrometer observation and 1D hydrodynamic numerical simulation coupled to the time-dependent ionization. The observation clearly shows that the strong redshift can be observed at the base of the flaring loop only during the impulsive phase. We performed two different numerical simulations to reproduce the strong downflows in FeXII and FeXV during the impulsive phase. By changing the thermal conduction coefficient, we carried out the numerical calculation of chromospheric evaporation in the thermal conduction dominant regime (conductivity coefficient κ{sub 0} = classical value) and the enthalpy flux dominant regime (κ{sub 0} = 0.1 × classical value). The chromospheric evaporation calculation in the enthalpy flux dominant regime could reproduce the strong redshift at the base of the flare during the impulsive phase. This result might indicate that the thermal conduction can be strongly suppressed in some cases of flare. We also find that time-dependent ionization effect is important to reproduce the strong downflows in Fe XII and Fe XV.

  2. The utility of rat models of impulsivity in developing pharmacotherapies for impulse control disorders

    PubMed Central

    Winstanley, Catharine A

    2011-01-01

    High levels of impulsive behaviours are a clinically significant symptom in a range of psychiatric disorders, such as attention deficit hyperactivity disorder, bipolar disorder, personality disorders, pathological gambling and substance abuse. Although often measured using questionnaire assessments, levels of different types of impulsivity can also be determined using behavioural tests. Rodent analogues of these paradigms have been developed, and similar neural circuitry has been implicated in their performance in both humans and rats. In the current review, the methodology underlying the measurement of different aspects of impulsive action and choice are considered from the viewpoint of drug development, with a focus on the continuous performance task (CPT), stop-signal task (SST), go/no-go and delay-discounting paradigms. Current issues impeding translation between animal and human studies are identified, and comparisons drawn between the acute effects of dopaminergic, noradrenergic and serotonergic compounds across species. Although the field could benefit from a more systematic determination of different pharmacological agents across paradigms, there are signs of strong concordance between the animal and human data. However, the type of impulsivity measured appears to play a significant role, with the SST and delay discounting providing more consistent effects for dopaminergic drugs, while the CPT and SST show better predictive validity so far for serotonergic and noradrenergic compounds. Based on the available data, it would appear that these impulsivity models could be used more widely to identify potential pharmacotherapies for impulse control disorders. Novel targets within the glutamatergic and serotonergic system are also suggested. LINKED ARTICLES This article is part of a themed issue on Translational Neuropharmacology. To view the other articles in this issue visit http://dx.doi.org/10.1111/bph.2011.164.issue-4 PMID:21410459

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

    PubMed Central

    Voon, Valerie; Reynolds, Brady; Brezing, Christina; Gallea, Cecile; Skaljic, Meliha; Ekanayake, Vindhya; Fernandez, Hubert; Potenza, Marc N; Dolan, Raymond J; Hallett, Mark

    2013-01-01

    Rationale Dopaminergic medication-related Impulse Control Disorders (ICDs) such as pathological gambling and compulsive shopping have been reported in Parkinson disease (PD). Hypothesis We hypothesized that dopamine agonists (DAs) would be associated with greater impulsive choice, or greater discounting of delayed rewards, in PD patients with ICDs (PDI). Methods Fourteen PDI patients, 14 PD controls without ICDs and 16 medication-free matched normal controls were tested on (i) the Experiential Discounting Task (EDT), a feedback-based intertemporal choice task, (ii) spatial working memory and (iii) attentional set shifting. The EDT was used to assess impulsivity choice (hyperbolic K-value), reaction time (RT) and decision conflict RT (the RT difference between high conflict and low conflict choices). PDI patients and PD controls were tested on and off DA. Results On the EDT, there was a group by medication interaction effect [F(1,26)=5.62; p=0.03] with pairwise analyses demonstrating that DA status was associated with increased impulsive choice in PDI patients (p=0.02) but not in PD controls (p=0.37). PDI patients also had faster RT compared to PD controls F(1,26)=7.51 p=0.01]. DA status was associated with shorter RT [F(3,24)=8.39, p=0.001] and decision conflict RT [F(1,26)=6.16, p=0.02] in PDI patients but not in PD controls. There were no correlations between different measures of impulsivity. PDI patients on DA had greater spatial working memory impairments compared to PD controls on DA (t=2.13, df=26, p=0.04). Conclusion Greater impulsive choice, faster RT, faster decision conflict RT and executive dysfunction may contribute to ICDs in PD. PMID:19838863

  4. Optoelectronic signal processing using finite impulse response neural networks

    NASA Astrophysics Data System (ADS)

    H. B. Xavier da Silveira, Paulo Eduardo

    2001-08-01

    This thesis investigates the use of finite impulse response neural network as the computational algorithm for efficient optoelectronic signal processing. The study begins with the analysis and development of different suitable algorithms, followed by the optoelectronic design of single-layer and multi-layer architectures, and it is concluded with the presentation of the results of a successful experimental implementation. First, finite impulse response adaptive filters and neural networks-the algorithmic building blocks-are introduced, followed by a description of finite impulse response neural networks. This introduction is followed by a historical background, describing early optoelectronic implementations of these algorithms. Next, different algorithms capable of temporal back-propagation are derived in detail, including a novel modification to the conventional algorithm, called delayed-feedback back- propagation. Based on these algorithms, different optoelectronic processors making use of adaptive volume holograms and three-dimensional optical processing are developed. Two single-layer architectures are presented: the input delay plane architecture and the output delay plane architecture. By combining them it is possible to implement both forward and backward propagation in two complementary multi-layer architectures: the first making use of the conventional temporal back-propagation and the second making use of delayed feedback back-propagation. Next, emphasis is given to a specific application: the processing of signals from adaptive antenna arrays. This research is initiated by computer simulations of different scenarios with multiple broadband signals and jammers, in planar and circular arrays, studying issues such as the effect of modulator non-linearities to the performance of the array, and the relation between the number of jammers and the final nulling depth. Two sets of simulations are presented: the first set applied to RF antenna arrays and the

  5. Pelvic radiation - discharge

    MedlinePlus

    Radiation of the pelvis - discharge; Cancer treatment - pelvic radiation; Prostate cancer - pelvic radiation; Ovarian cancer - pelvic radiation; Cervical cancer - pelvic radiation; Uterine cancer - pelvic radiation; Rectal cancer - ...

  6. 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.

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

    PubMed Central

    Lim, Meerae; Lee, Soojung

    2016-01-01

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

  8. Increased reflection impulsivity in patients with ephedrone induced Parkinsonism

    PubMed Central

    Djamshidian, Atbin; Sanotsky, Yanosh; Matviyenko, Yuriy; O’Sullivan, Sean S.; Sharman, Stephen; Selikhova, Marianna; Fedoryshyn, Ludmyla; Filts, Yuriy; Bearn, Jenny; Lees, Andrew J.; Averbeck, Bruno B.

    2012-01-01

    Aims To examine a syndrome of chronic manganism that occurs in drug addicts in Eastern Europe who use intravenous methcathinone (ephedrone) contaminated with potassium permanganate. The basal ganglia, especially the globus pallidus and the putamen, are damaged irreversibly in many cases. Routine neuropsychological assessment has revealed no cognitive deficits despite widespread abnormalities on brain imaging studies and severe extrapyramidal motor handicap on clinical examination. Design Case control study. Setting Ephedrone patients and patients with opioid dependence were recruited from Lviv, Ukraine. Participants We tested 15 patients with ephedrone induced toxicity, 13 opiate dependent patients, who were receiving opioid replacement therapy and 18 matched healthy volunteers. Measurements The ‘beads task’, an information gathering task to assess reflection impulsivity was used and feedback learning, working memory and risk taking were also assessed. Findings Opiate dependent patients differed from controls on three out of four tasks, whereas ephedrone patients differed from controls on only one task. More specifically both patient groups were more impulsive and made more irrational choices on the beads task than controls (p<0.001). However, ephedrone patients had no deficits in working memory (p>0.1) or risk taking (p>0.1) compared with controls. Opioid dependent patients had significantly worse working memory (p<0.001) and were significantly more risk prone than controls (p=0.002). Conclusions Ephedrone patients may have similar deficits in information gathering and decision making to opiate dependent patients, with preservation of working memory and risk taking. This may reflect specific damage to anterior cingulate- basal ganglia loops. PMID:23228208

  9. Energetic electrons in impulsive solar flares

    NASA Technical Reports Server (NTRS)

    Batchelor, D. A.

    1984-01-01

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

  10. Electron acceleration in impulsive solar flares

    SciTech Connect

    Kane, S.R.; Benz, A.O.; Treumann, R.A.

    1982-12-01

    Simultaneous observations of the hard X-ray, microwave, and type III and DCIM (decimetric)radio bursts associated with the 1978 December 4 solar flare have been used to study the physical parameters relevant to the acceleration and propagation of energetic electrons during the impulsive phase of a solar flare. The hard X-ray observations were made with the X-ray spectrometer aboard the ISEE 3 spacecraft. The radio spectra in metric and decimetric bands were recorded with the radiospectrograph located at Durnten, near Zurich, Switzerland. The microwave observations were made at the Sagamore Hill and Bern observatories. The three metric type III bursts coincided with the three most prominent hard X-ray peaks. This is the fist time a clear one-to-one association between single type III bursts and hard X-ray peaks has been established. The average delay of the type III bursts with respect to the X-ray peaks was 0.5 s. The harder the X-ray spectrum, the higher was the drift rate of the associated type III burst. The characteristic electron energies inferred from the drift rate are of the order of 70 keV. The observed increase in the high-frequency cutoff of the metric type III bursts during the impulsive phase has been examined in terms of the decreasing altitude of the electron acceleration/injection region, the increasing hardness of the electron spectrum, and the decreasing acceleration time. A pulsating decimetric continuum (DCIM) was also found to be present during and before the impulsive phase. The DCIM source seems to coincide spatially with the electron acceleration region and the (projected) origin of the associated type II shock.ction region.

  11. Proton hopping: a proposed mechanism for myelinated axon nerve impulses.

    PubMed

    Kier, Lemont B; Tombes, Robert M

    2013-04-01

    Myelinated axon nerve impulses travel 100 times more rapidly than impulses in non-myelinated axons. Increased speed is currently believed to be due to 'hopping' or 'saltatory propagation' along the axon, but the mechanism by which impulses flow has never been adequately explained. We have used modeling approaches to simulate a role for proton hopping in the space between the plasma membrane and myelin sheath as the mechanism of nerve action-potential flow.

  12. Stochastic Impulse Control of Non-Markovian Processes

    SciTech Connect

    Djehiche, Boualem; Hamadene, Said Hdhiri, Ibtissam

    2010-02-15

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

  13. Lyapunov Control of Quantum Systems with Impulsive Control Fields

    PubMed Central

    Yang, Wei; Sun, Jitao

    2013-01-01

    We investigate the Lyapunov control of finite-dimensional quantum systems with impulsive control fields, where the studied quantum systems are governed by the Schrödinger equation. By three different Lyapunov functions and the invariant principle of impulsive systems, we study the convergence of quantum systems with impulsive control fields and propose new results for the mentioned quantum systems in the form of sufficient conditions. Two numerical simulations are presented to illustrate the effectiveness of the proposed control method. PMID:23766712

  14. Nerve impulses increase glial intercellular permeability.

    PubMed

    Marrero, H; Orkand, R K

    1996-03-01

    Coordinating the activity of neurons and their satellite glial cells requires mechanisms by which glial cells detect neuronal activity and change their properties as a result. This study monitors the intercellular diffusion of the fluorescent dye Lucifer Yellow (LY), following its injection into glial cells of the frog optic nerve, and demonstrates that nerve impulses increase the permeability of interglial gap junctions. Consequently, the spatial buffer capacity of the neuroglial cell syncytium for potassium, other ions, and small molecules will be enhanced; this may facilitate glial function in maintaining homeostasis of the neuronal microenvironment. PMID:8833199

  15. Impulse absorption by horizontal magnetic granular chain

    NASA Astrophysics Data System (ADS)

    Leng, Dingxin; Wang, Xiaojie; Liu, Guijie; Sun, Lingyu

    2016-02-01

    The granular medium is known as a protecting material for shock mitigation. We study the impulse absorption of an alignment of magnetic spheres placed horizontally under a non-uniform magnetic field. The phenomenon of the wave dispersion is presented. This system can absorb 85% ˜ 95% (88% ˜ 98%) of the incident peak force (energy) under the applied magnetic field strength in 0.1 T ˜ 1.0 T. The shock attenuation capacities are enhanced by the increment of field strength. With an intelligent control system, it is conceivable that the magnetic granular chain may offer possibilities in developing adaptive shock protectors.

  16. The genetic correlation between procrastination and impulsivity.

    PubMed

    Loehlin, John C; Martin, Nicholas G

    2014-12-01

    The reported genetic correlation of 1.0 between the traits of procrastination and impulsivity (Gustavson, D. E., Miyake, A., Hewitt, J. K., & Friedman, N. P. (2014). Psychological Science), which was held to support an evolutionary origin of the relationship between the two traits, was tested in data from two large samples of twins from Australia. A genetic correlation of 0.299 was obtained. It was concluded that, although the presence of a genetic correlation between the two traits was supported, the modest magnitude of the correlation was such as to be consistent with many possible hypotheses, evolutionary and otherwise, about causal relationships between the traits in question. PMID:25431285

  17. The genetic correlation between procrastination and impulsivity.

    PubMed

    Loehlin, John C; Martin, Nicholas G

    2014-12-01

    The reported genetic correlation of 1.0 between the traits of procrastination and impulsivity (Gustavson, D. E., Miyake, A., Hewitt, J. K., & Friedman, N. P. (2014). Psychological Science), which was held to support an evolutionary origin of the relationship between the two traits, was tested in data from two large samples of twins from Australia. A genetic correlation of 0.299 was obtained. It was concluded that, although the presence of a genetic correlation between the two traits was supported, the modest magnitude of the correlation was such as to be consistent with many possible hypotheses, evolutionary and otherwise, about causal relationships between the traits in question.

  18. Diagnostics and Impulse Performance of Laser-Ablative Propulsion

    SciTech Connect

    Sasoh, Akihiro; Mori, Koichi; Anju, Kohei; Suzuki, Koji; Shimono, Masaya; Sawada, Keisuke

    2008-04-28

    Pressure time variations and associated flows induced by pulsed laser ablation were experimentally studied using the Velocity Interferometer System for Any Reflector (VISAR) and framing Schlieren visualization. The combination of either aluminum or polyacetal target and TEA CO{sub 2} laser pulse were examined. The VISAR measurement resolved that the pressure modulated from the laser power variation in the impulse generation processes. Integrated impulse induced by repetative CO{sub 2} laser pulses was measured using a torsion-type impulse balance. The effect of the ambient pressure was significant. The measured impulse characteristics were closely associated with target surface morphology and fluid dynamics.

  19. Minimum impulse transfers to rotate the line of apsides

    NASA Technical Reports Server (NTRS)

    Phong, Connie; Sweetser, Theodore H.

    2005-01-01

    Transfer between two coplanar orbits can be accomplished via a single impulse if the two orbits intersect. Optimization of a single-impulse transfer, however, is not possible since the transfer orbit is completely constrained by the initial and final orbits. On the other hand, two-impulse transfers are possible between any two terminal orbits. While optimal scenarios are not known for the general two-impulse case, there are various approximate solutions to many special cases. We consider the problem of an inplane rotation of the line of apsides, leaving the size and shape of the orbit unaffected.

  20. Minimum impulse transfers to rotate the line of apsides

    NASA Technical Reports Server (NTRS)

    Phong, Connie; Sweetser, Theodore H.

    2005-01-01

    While an optimal scenario for the general two-impulse transfer between coplanar orbits is not known, there are optimal scenarios for various special cases. We consider in-plane rotations of the line of apsides. Numerical comparisons with a trajectory optimization program support the claim that the optimal deltaV required by two impulses is about half that required by a single impulse, regardless of semi-major axes. We observe that this estimate becomes more conservative with larger angles of rotation and eccentricities, and thus also present a more accurate two-impulse rotation deltaV estimator.

  1. Dissecting Impulsivity and its Relationships to Drug Addictions

    PubMed Central

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

    2015-01-01

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

  2. Sleep and Impulsivity in Parkinson’s Disease

    PubMed Central

    Scullin, Michael K.; Sollinger, Ann B.; Land, Julia; Wood-Siverio, Cathy; Zanders, Lavezza; Lee, Raven; Freeman, Alan; Goldstein, Felicia C.; Bliwise, Donald L.; Factor, Stewart A.

    2013-01-01

    Background Impulsive behavior and poor sleep are important non-motor features of Parkinson’s disease (PD) that negatively impact the quality of life of patients and their families. Previous research suggests a higher level of sleep complaints in PD patients who demonstrate impulsive behaviors, but the nature of the sleep disturbances has yet to be comprehensively tested. Methods Consecutive idiopathic PD patients (N=143) completed the Minnesota Impulse Disorder Interview and a sleep questionnaire that assessed sleep efficiency, excessive daytime sleepiness, restless legs symptoms, snoring, dreams/nightmares, and nocturia. Patients were also given a Unified Parkinson’s Disease Rating Scale motor examination and they completed cognitive testing. Results Impulsive PD patients endorsed more sleep complaints than non-impulsive PD patients. The group difference was primarily attributable to poor sleep efficiency (e.g., greater nocturnal awakenings), p < .01, and greater daytime sleepiness, p < .01, in the impulsive PD patients. Interestingly, restless legs symptoms were also greater in the impulsive PD patients, p < .05. The results could not be explained by medications or disease severity. Conclusions Poor sleep efficiency, restless legs symptoms, and increased daytime sleepiness are associated with impulsivity in PD. Longitudinal studies are needed to determine whether sleep disturbances precede impulsivity in PD. PMID:23880026

  3. 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.

  4. Impulsive noise of printers: measurement metrics and their subjective correlation

    NASA Astrophysics Data System (ADS)

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

    2005-09-01

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

  5. Minimum-fuel multiple-impulse apsidal orbital transfers

    NASA Astrophysics Data System (ADS)

    Kirpichnikov, S. N.

    1990-01-01

    The paper is concerned with the problem of minimum-fuel impulse transfers between specified nonintersecting Keplerian boundary orbits. The qualitative criteria of optimal single-impulse transfer orbits are defined, and multiple-impulse minimum-fuel apsidal transfers are investigated for the case of orbits with a common line of apsides. For circular (coplanar and noncoplanar) boundary orbits, the global optimality of the single-impulse Hohmann transfer in the plane of the initial orbit is demonstrated in the case where the ratio of the initial orbit radius to the final orbit radius does not exceed 4.828.

  6. Genetic association of impulsivity in young adults: a multivariate study

    PubMed Central

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

    2014-01-01

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

  7. Impulse source versus dodecahedral loudspeaker for measuring parameters derived from the impulse response in room acoustics.

    PubMed

    San Martín, Ricardo; Arana, Miguel; Machín, Jorge; Arregui, Abel

    2013-07-01

    This study investigates the performance of dodecahedral and impulse sources when measuring acoustic parameters in enclosures according to ISO 3382-1 [Acoustics-Measurement of room acoustic parameters. Part 1: Performance spaces (International Organization for Standardization, Geneva, Switzerland, 2009)]. In general, methods using speakers as a sound source are limited by their frequency response and directivity. On the other hand, getting impulse responses from impulse sources typically involves a lack of repeatability, and it is usually necessary to average several measurements for each position. Through experiments in different auditoriums that recreate typical situations in which the measurement standard is applied, it is found that using impulse sources leads to greater variation in the results, especially at low frequencies. However, this prevents subsequent dispersions due to variables that this technique does not require, such as the orientation of the emitting source. These dispersions may be relevant at high frequencies exceeding the established tolerance criteria for certain parameters. Finally, a new descriptor for dodecahedral sources reflecting the influence their lack of omnidirectionality produces on measuring acoustic parameters is proposed.

  8. Impulsivity and the sexes: measurement and structural invariance of the UPPS-P Impulsive Behavior Scale.

    PubMed

    Cyders, Melissa A

    2013-02-01

    Before it is possible to test whether men and women differ in impulsivity, it is necessary to evaluate whether impulsivity measures are invariant across sex. The UPPS-P Impulsive Behavior Scale (negative urgency, lack of premeditation, lack of perseverance, and sensation seeking, with added subscale of positive urgency) is one measure of five dispositions toward rash action that has shown to have robust and clinically useful relationships among risk-taking outcomes. In the current research, the author examined (a) the psychometric measurement invariance of the UPPS-P across sex, (b) the scale's structural invariance across sex, and (c) whether the five impulsivity traits differentially relate to risk outcomes as a function of sex. In a sample of 1,372 undergraduates, the author found evidence for measurement and invariance across sex: Thus, comparisons of men and women on the UPPS-P can be considered valid. Additionally, although males tend to report higher levels of sensation seeking and positive urgency (and possibly lack of perseverance), the relationships between the UPPS-P traits and risk outcomes were generally invariant across sex. The UPPS-P appears to function comparably across males and females, and mean differences on this scale between the sexes can be thought to reflect trait-level differences. PMID:22096214

  9. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, B.E.; Miller, J.L.; Ault, E.R.

    1994-08-23

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window. 2 figs.

  10. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, Bruce E.; Miller, John L.; Ault, Earl R.

    1994-01-01

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window.

  11. Lithium battery discharge tests

    NASA Technical Reports Server (NTRS)

    Johnson, C. J.

    1980-01-01

    The long term discharge of a variety of lithium cells was characterized and the susceptibility of the cells to chemical variation during the slow discharge was tested. A shunt resistor was set across the terminals to monitor the voltage as a function of time. Failures were identified by premature voltage drops.

  12. Hollow Electrode Discharge Triodes

    NASA Astrophysics Data System (ADS)

    Schoenbach, K. H.; Peterkin, F. E.; Tessnow, T.

    1996-10-01

    The current through a direct current micro-hollow electrode (electrode hole diameter: 0.7 mm) discharge in argon was shown to be controllable by means of a third, external electrode placed close to the cathode opening. By increasing the potential of the positively biased control electrode from zero to 30 V the discharge current could be linearly reduced from 5 μA to 0.75 μA, at a discharge voltage of 300 V. The current-voltage characteristic of the micro-hollow electrode discharge was found to have a positive slope, allowing parallel discharge operation without ballast. By drilling holes through a metal-plated, dielectric film, an array of hollow electrode discharges could be generated. It was shown that each discharge responds individually to variations in the potential of the corresponding external control electrode. The simplicity of the electrode configuration and the possibility of linear, electrical control of the individual discharge currents offers the possibility to use these triode arrays in addressable flat panel displays (patent pending).

  13. Partial sleep deprivation impacts impulsive action but not impulsive decision-making.

    PubMed

    Demos, K E; Hart, C N; Sweet, L H; Mailloux, K A; Trautvetter, J; Williams, S E; Wing, R R; McCaffery, J M

    2016-10-01

    Sleep deprivation may lead to increased impulsivity, however, previous literature has focused on examining effects of total sleep deprivation (TSD) rather than the more common condition, partial sleep deprivation (PSD) or 'short sleep'. Moreover, it has been unclear whether PSD impacts impulse-related cognitive processes, and specifically if it differentially affects impulsive action versus impulsive decision-making. We sought to determine if short compared to long sleep (6 vs. 9h/night) impacts impulsive action via behavioral inhibition (Go/No-Go), and/or impulsive decision-making processes of risk taking (Balloon Analogue Risk Task [BART]) and preferences for immediate over delayed rewards (Delay Discounting). In a within-subject design, 34 participants (71% female, mean age=37.0years, SD=10.54) were assigned to four consecutive nights of 6h/night (short sleep) and 9h/night (long sleep) in their own home in random counterbalanced order. Sleep was measured via wrist-worn actigraphs to confirm adherence to the sleep schedules (mean short sleep=5.9h, SD=0.3; mean long sleep=8.6h, SD=0.3, p<0.001). The Go/No-Go, BART, and Delay Discounting tasks were completed following both sleep conditions. Participants had more inhibition errors on the Go/No-Go task after short (mean false alarms=19.79%, SD=14.51) versus long sleep (mean=15.97%, SD=9.51, p=0.039). This effect was strongest in participants reporting longer habitual time in bed (p=0.04). There were no differences in performance following long- versus short-sleep for either delay discounting or the BART (p's>0.4). Overall, these results indicate that four days of PSD diminishes behavioral inhibition abilities, but may not alter impulsive decision-making. These findings contribute to the emerging understanding of how partial sleep deprivation, currently an epidemic, impacts cognitive ability. Future research should continue to explore the connection between PSD and cognitive functions, and ways to minimize the

  14. Partial sleep deprivation impacts impulsive action but not impulsive decision-making.

    PubMed

    Demos, K E; Hart, C N; Sweet, L H; Mailloux, K A; Trautvetter, J; Williams, S E; Wing, R R; McCaffery, J M

    2016-10-01

    Sleep deprivation may lead to increased impulsivity, however, previous literature has focused on examining effects of total sleep deprivation (TSD) rather than the more common condition, partial sleep deprivation (PSD) or 'short sleep'. Moreover, it has been unclear whether PSD impacts impulse-related cognitive processes, and specifically if it differentially affects impulsive action versus impulsive decision-making. We sought to determine if short compared to long sleep (6 vs. 9h/night) impacts impulsive action via behavioral inhibition (Go/No-Go), and/or impulsive decision-making processes of risk taking (Balloon Analogue Risk Task [BART]) and preferences for immediate over delayed rewards (Delay Discounting). In a within-subject design, 34 participants (71% female, mean age=37.0years, SD=10.54) were assigned to four consecutive nights of 6h/night (short sleep) and 9h/night (long sleep) in their own home in random counterbalanced order. Sleep was measured via wrist-worn actigraphs to confirm adherence to the sleep schedules (mean short sleep=5.9h, SD=0.3; mean long sleep=8.6h, SD=0.3, p<0.001). The Go/No-Go, BART, and Delay Discounting tasks were completed following both sleep conditions. Participants had more inhibition errors on the Go/No-Go task after short (mean false alarms=19.79%, SD=14.51) versus long sleep (mean=15.97%, SD=9.51, p=0.039). This effect was strongest in participants reporting longer habitual time in bed (p=0.04). There were no differences in performance following long- versus short-sleep for either delay discounting or the BART (p's>0.4). Overall, these results indicate that four days of PSD diminishes behavioral inhibition abilities, but may not alter impulsive decision-making. These findings contribute to the emerging understanding of how partial sleep deprivation, currently an epidemic, impacts cognitive ability. Future research should continue to explore the connection between PSD and cognitive functions, and ways to minimize the

  15. Volume Diffuse Dielectric Barrier Discharge Plasma Produced by Nanosecond High Voltage Pulse in Airflow

    NASA Astrophysics Data System (ADS)

    Qi, Haicheng; Gao, Wei; Fan, Zhihui; Liu, Yidi; Ren, Chunsheng

    2016-05-01

    Volume diffuse dielectric barrier discharge (DBD) plasma is produced in subsonic airflow by nanosecond high-voltage pulse power supply with a plate-to-plate discharge cell at 6 mm air gap length. The discharge images, optical emission spectra (OES), the applied voltage and current waveforms of the discharge at the changed airflow rates are obtained. When airflow rate is increased, the transition of the discharge mode and the variations of discharge intensity, breakdown characteristics and the temperature of the discharge plasma are investigated. The results show that the discharge becomes more diffuse, discharge intensity is decreased accompanied by the increased breakdown voltage and time lag, and the temperature of the discharge plasma reduces when airflow of small velocity is introduced into the discharge gap. These phenomena are because that the airflow changes the spatial distribution of the heat and the space charge in the discharge gap. supported by National Natural Science Foundation of China (No. 51437002)

  16. HOLLOW CARBON ARC DISCHARGE

    DOEpatents

    Luce, J.S.

    1960-10-11

    A device is described for producing an energetic, direct current, hollow, carbon-arc discharge in an evacuated container and within a strong magnetic field. Such discharges are particularly useful not only in dissociation and ionization of high energy molecular ion beams, but also in acting as a shield or barrier against the instreaming of lowenergy neutral particles into a plasma formed within the hollow discharge when it is used as a dissociating mechanism for forming the plasma. There is maintained a predetermined ratio of gas particles to carbon particles released from the arc electrodes during operation of the discharge. The carbon particles absorb some of the gas particles and are pumped along and by the discharge out of the device, with the result that smaller diffusion pumps are required than would otherwise be necessary to dispose of the excess gas.

  17. GAS DISCHARGE DEVICES

    DOEpatents

    Jefferson, S.

    1958-11-11

    An apparatus utilized in introducing tritium gas into envelope of a gas discharge device for the purpose f maintaining the discharge path in ionized condition is described. ln addition to the cathode and anode, the ischarge device contains a zirconium or tantalum ilament arranged for external excitation and a metallic seed containing tritium, and also arranged to have a current passed through it. Initially, the zirconium or tantalum filament is vaporized to deposit its material adjacent the main discharge region. Then the tritium gas is released and, due to its affinity for the first released material, it deposits in the region of the main discharge where it is most effective in maintaining the discharge path in an ionized condition.

  18. Community nurses & discharge planning.

    PubMed

    Worth, A; Tierney, A; Lockerbie, L

    The role of community nurses in discharge planning for elderly patients leaving hospital is of increasing importance in the wake of the NHS and Community Care Act 1990. Community nurses can play a key role in contributing to pre-discharge assessments and in providing continuing post-discharge assessment and care. The Nursing Research Unit at the University of Edinburgh conducted a survey early in 1993, just prior to implementation of the Community Care Act in Scotland, to ascertain the views and experiences of a national 1 in 3 sample of community nurses relating to the discharge of elderly people from acute hospitals. This article presents the results of that survey and offers recommendations regarding the role of community nurses in discharge planning for elderly patients.

  19. CO-AXIAL DISCHARGES

    DOEpatents

    Luce, J.S.; Smith, L.P.

    1960-11-22

    A method and apparatus are given for producing coaxial arc discharges in an evacuated enclosure and within a strong, confining magnetic field. The arcs are maintained at a high potential difference. Electrons will diffuse to the more positive arc from the negative arc, and positive ions will diffuse from the more positive arc to the negative arc. Coaxial arc discharges have the advantage that ions which return to strike the positive arc discharge will lose no energy since they do not strike a solid wall or electrode. Those discharges are useful in confining an ionized plasma between the discharges, and have the advantage of preventing impurities from the walls of the enclosure from entering ihe plasma area because of the arc barrier set up bv the cylindrical outer arc.

  20. Co-axial discharges

    DOEpatents

    Luce, J. S.; Smith, L. P.

    1960-11-22

    An apparatus is described for producing coaxial arc discharges in an evacuated enclosure and within a strong, confining magnetic field. The arcs are maintained at a high potential difference. Electrons diffuse to the more positive arc from the negative arc, and positive ions diffuse from the more positive arc to the negative arc. Coaxial arc discharges have the advantuge that ions that return to strike the positive arc discharge will lose no energy since they do not strike a solid wall or electrode. These discharges are useful in confining an ionized plasma between the discharges and have the advantage of preventing impurities from the walls of the enclosure from entering the plasma area because of the arc barrier set up by the cylindrical outer arc. (auth)

  1. Trait Impulsivity and Anhedonia: Two Gateways for the Development of Impulse Control Disorders in Parkinson's Disease?

    PubMed

    Houeto, Jean-Luc; Magnard, Robin; Dalley, Jeffrey W; Belin, David; Carnicella, Sebastien

    2016-01-01

    Apathy and impulsivity are two major comorbid syndromes of Parkinson's disease (PD) that may represent two extremes of a behavioral spectrum modulated by dopamine-dependent processes. PD is characterized by a progressive loss of dopaminergic neurons in the substantia nigra pars compacta to which are attributed the cardinal motor symptoms of the disorder. Dopamine replacement therapy (DRT), used widely to treat these motor symptoms, is often associated with deficits in hedonic processing and motivation, including apathy and depression, as well as impulse control disorders (ICDs). ICDs comprise pathological gambling, hypersexuality, compulsive shopping, binge eating, compulsive overuse of dopaminergic medication, and punding. More frequently observed in males with early onset PD, ICDs are associated not only with comorbid affective symptoms, such as depression and anxiety, but also with behavioral traits, such as novelty seeking and impulsivity, as well as with personal or familial history of alcohol use. This constellation of associated risk factors highlights the importance of inter-individual differences in the vulnerability to develop comorbid psychiatric disorders in PD patients. Additionally, withdrawal from DRT in patients with ICDs frequently unmasks a severe apathetic state, suggesting that apathy and ICDs may be caused by overlapping neurobiological mechanisms within the cortico-striato-thalamo-cortical networks. We suggest that altered hedonic and impulse control processes represent distinct prodromal substrates for the development of these psychiatric symptoms, the etiopathogenic mechanisms of which remain unknown. Specifically, we argue that deficits in hedonic and motivational states and impulse control are mediated by overlapping, yet dissociable, neural mechanisms that differentially interact with DRT to promote the emergence of ICDs in vulnerable individuals. Thus, we provide a novel heuristic framework for basic and clinical research to better

  2. Improving Hospital Discharge Time

    PubMed Central

    El-Eid, Ghada R.; Kaddoum, Roland; Tamim, Hani; Hitti, Eveline A.

    2015-01-01

    Abstract Delays in discharging patients can impact hospital and emergency department (ED) throughput. The discharge process is complex and involves setting specific challenges that limit generalizability of solutions. The aim of this study was to assess the effectiveness of using Six Sigma methods to improve the patient discharge process. This is a quantitative pre and post-intervention study. Three hundred and eighty-six bed tertiary care hospital. A series of Six Sigma driven interventions over a 10-month period. The primary outcome was discharge time (time from discharge order to patient leaving the room). Secondary outcome measures included percent of patients whose discharge order was written before noon, percent of patients leaving the room by noon, hospital length of stay (LOS), and LOS of admitted ED patients. Discharge time decreased by 22.7% from 2.2 hours during the preintervention period to 1.7 hours post-intervention (P < 0.001). A greater proportion of patients left their room before noon in the postintervention period (P < 0.001), though there was no statistical difference in before noon discharge. Hospital LOS dropped from 3.4 to 3.1 days postintervention (P < 0.001). ED mean LOS of patients admitted to the hospital was significantly lower in the postintervention period (6.9 ± 7.8 vs 5.9 ± 7.7 hours; P < 0.001). Six Sigma methodology can be an effective change management tool to improve discharge time. The focus of institutions aspiring to tackle delays in the discharge process should be on adopting the core principles of Six Sigma rather than specific interventions that may be institution-specific. PMID:25816029

  3. A centre-triggered magnesium fuelled cathodic arc thruster uses sublimation to deliver a record high specific impulse

    NASA Astrophysics Data System (ADS)

    Neumann, Patrick R. C.; Bilek, Marcela; McKenzie, David R.

    2016-08-01

    The cathodic arc is a high current, low voltage discharge that operates in vacuum and provides a stream of highly ionised plasma from a solid conducting cathode. The high ion velocities, together with the high ionisation fraction and the quasineutrality of the exhaust stream, make the cathodic arc an attractive plasma source for spacecraft propulsion applications. The specific impulse of the cathodic arc thruster is substantially increased when the emission of neutral species is reduced. Here, we demonstrate a reduction of neutral emission by exploiting sublimation in cathode spots and enhanced ionisation of the plasma in short, high-current pulses. This, combined with the enhanced directionality due to the efficient erosion profiles created by centre-triggering, substantially increases the specific impulse. We present experimentally measured specific impulses and jet power efficiencies for titanium and magnesium fuels. Our Mg fuelled source provides the highest reported specific impulse for a gridless ion thruster and is competitive with all flight rated ion thrusters. We present a model based on cathode sublimation and melting at the cathodic arc spot explaining the outstanding performance of the Mg fuelled source. A further significant advantage of an Mg-fuelled thruster is the abundance of Mg in asteroidal material and in space junk, providing an opportunity for utilising these resources in space.

  4. Pulsed electrical discharge in conductive solution

    NASA Astrophysics Data System (ADS)

    Panov, V. A.; Vasilyak, L. M.; Vetchinin, S. P.; Pecherkin, V. Ya; Son, E. E.

    2016-09-01

    Electrical discharge in a conductive solution of isopropyl alcohol in tap water (330 μ S cm‑1) has been studied experimentally applying high voltage millisecond pulses (rise time  ∼0.4 μ \\text{s} , amplitude up to 15 kV, positive polarity) to a pin anode electrode. Dynamic current–voltage characteristics synchronized with high-speed images of the discharge were studied. The discharge was found to develop from high electric field region in the anode vicinity where initial conductive current with density  ∼100 A cm‑2 results in fast heating and massive nucleation of vapor bubbles. Discharges in nucleated bubbles then produce a highly conductive plasma region and facilitate overheating instability development with subsequent formation of a thermally ionized plasma channel. The measured plasma channel propagation speed was 3–15 m s‑1. A proposed thermal model of plasma channel development explains the low observed plasma channel propagation speed.

  5. Pulsed electrical discharge in conductive solution

    NASA Astrophysics Data System (ADS)

    Panov, V. A.; Vasilyak, L. M.; Vetchinin, S. P.; Pecherkin, V. Ya; Son, E. E.

    2016-09-01

    Electrical discharge in a conductive solution of isopropyl alcohol in tap water (330 μ S cm-1) has been studied experimentally applying high voltage millisecond pulses (rise time  ˜0.4 μ \\text{s} , amplitude up to 15 kV, positive polarity) to a pin anode electrode. Dynamic current-voltage characteristics synchronized with high-speed images of the discharge were studied. The discharge was found to develop from high electric field region in the anode vicinity where initial conductive current with density  ˜100 A cm-2 results in fast heating and massive nucleation of vapor bubbles. Discharges in nucleated bubbles then produce a highly conductive plasma region and facilitate overheating instability development with subsequent formation of a thermally ionized plasma channel. The measured plasma channel propagation speed was 3-15 m s-1. A proposed thermal model of plasma channel development explains the low observed plasma channel propagation speed.

  6. Low cost impulse compatible wideband antenna

    DOEpatents

    Rosenbury, Erwin T.; Burke, Gerald J.; Nelson, Scott D.; Stever, Robert D.; Governo, George K.; Mullenhoff, Donald J.

    2002-01-01

    An antenna apparatus and method for building the antenna is disclosed. Impulse signals travel through a feed point of the antenna with respect to a ground plane. A geometric fin structure is connected to the feed point, and through a termination resistance to the ground plane. A geometric ridge structure connected to the ground is positioned with respect to the fin in order to receive and radiate electromagnetic energy from the impulse signal at a predetermined impedance and over a predetermined set of frequencies. The fin and ridge can be either a wire or a planar surface. The fin and ridge may be disposed within a radiation cavity such as a horn. The radiation cavity is constructed of stamped and etched metal sheets bent and then soldered together. The fin and ridge are also formed from metal sheets or wires. The fin is attached to the feed point and then to the cavity through a termination resistance. The ridge is attached to the cavity and disposed with respect to the fin in order to achieve a particular set of antenna characteristics.

  7. Force-Time Entropy of Isometric Impulse.

    PubMed

    Hsieh, Tsung-Yu; Newell, Karl M

    2016-01-01

    The relation between force and temporal variability in discrete impulse production has been viewed as independent (R. A. Schmidt, H. Zelaznik, B. Hawkins, J. S. Frank, & J. T. Quinn, 1979 ) or dependent on the rate of force (L. G. Carlton & K. M. Newell, 1993 ). Two experiments in an isometric single finger force task investigated the joint force-time entropy with (a) fixed time to peak force and different percentages of force level and (b) fixed percentage of force level and different times to peak force. The results showed that the peak force variability increased either with the increment of force level or through a shorter time to peak force that also reduced timing error variability. The peak force entropy and entropy of time to peak force increased on the respective dimension as the parameter conditions approached either maximum force or a minimum rate of force production. The findings show that force error and timing error are dependent but complementary when considered in the same framework with the joint force-time entropy at a minimum in the middle parameter range of discrete impulse.

  8. Parameters Determination of Oscillatory Impulse Current Waveform

    NASA Astrophysics Data System (ADS)

    Sato, Shuji; Nishimura, Seisuke; Seki, Shingo

    This paper proposes numerical techniques to distil waveform parameters out of digitally measured data of oscillatory impulse current. The first method, to be used for liner circuit, based on a curve-fitting technique in which a smooth analytical curve is defined to fit the noise-superposed measured data. The waveform parameters are derived from the curve. The algorithm is examined its performance using a measured waveform data which is obtained from a circuit composed of linear elements only. It is not rare when impulse current is measured in a circuit with non-linear element, namely an arrester. After carefully observed behaviours of the circuit current when the non-linear element turns on and off, authors developed two algorithms capable to determine the parameters from the recorded data obtained from a circuit having a ZnO arrester. The developed algorithm processed the waveform data generated by TDG which is to be issued in 2009 as a part of IEC 61083-2. The details of the algorithm are to be demonstrated in the paper.

  9. Examining Impulse-Variability in Kicking.

    PubMed

    Chappell, Andrew; Molina, Sergio L; McKibben, Jonathon; Stodden, David F

    2016-07-01

    This study examined variability in kicking speed and spatial accuracy to test the impulse-variability theory prediction of an inverted-U function and the speed-accuracy trade-off. Twenty-eight 18- to 25-year-old adults kicked a playground ball at various percentages (50-100%) of their maximum speed at a wall target. Speed variability and spatial error were analyzed using repeated-measures ANOVA with built-in polynomial contrasts. Results indicated a significant inverse linear trajectory for speed variability (p < .001, η2= .345) where 50% and 60% maximum speed had significantly higher variability than the 100% condition. A significant quadratic fit was found for spatial error scores of mean radial error (p < .0001, η2 = .474) and subject-centroid radial error (p < .0001, η2 = .453). Findings suggest variability and accuracy of multijoint, ballistic skill performance may not follow the general principles of impulse-variability theory or the speed-accuracy trade-off.

  10. Different subtypes of impulsivity differentiate uncontrolled eating and dietary restraint.

    PubMed

    Leitch, Margaret A; Morgan, Michael J; Yeomans, Martin R

    2013-10-01

    The current study explored the relationship between three subtypes of impulsivity (Reflection Impulsivity, Impulsive Choice, and Impulsive Action) and measures of uncontrolled eating (TFEQ-D) and restraint (TFEQ-R). Eighty women classified as scoring higher or lower on TFEQ-D and TFEQ-R completed the Matching Familiar Figures Test (MFFT20), Delay Discounting Task (DDT), a Go No Go task, Balloon Analogue Risk Task (BART), and the Barrett Impulsivity Scale-11 (BIS-11). To test whether these relationships were affected by enforced controls overeating, half of the participants fasted the night before and ate breakfast in the laboratory before testing and half had no such control. Women scoring higher on the TFEQ-D were significantly more impulsive on the MFFT20 and BIS-11 overall but not on DDT, Go No Go or BART. Women scoring higher on TFEQ-R were significantly less impulsive on the Go No Go task but did not differ on other measures. The eating manipulation modulated responses on the BART and BIS-11 non-planning scale depending on TFEQ-D classification. These results confirm recent data that high scores on TFEQ-D are related to impulsivity, but imply this relates more to Reflection Impulsivity rather than Impulsive Choice or Action. In contrast restrained eating was associated with better inhibitory control. Taken together, these results suggest that subtypes of impulsivity further differentiate uncontrolled eating and restraint, and suggest that a poor ability to reflect on decisions may underlie some aspects of overeating. PMID:23702263

  11. The role of serotonin in impulsive aggression, suicide, and homicide in adolescents and adults: a literature review.

    PubMed

    Glick, Amy R

    2015-05-01

    This is a literature review discussing previous studies on the associations between impulsive aggression and the serotonergic system in adults, adolescents, and children. The review demonstrates that there is a clear association between low cerebrospinal fluid serotonin and impulsive aggression. However, studies on neurotransmitter receptor profiles, functional imaging, genetics, and epigenetics reviewed in this article suggest a more complicated picture that includes consideration of gene vs. environment in the evaluation of risk. Serotonin supplementation studies suggest that selective serotonin reuptake inhibitors may reduce impulsive aggression in some adults but are less effective in adults with pathological aggression and also in children and adolescents. Child and adolescent studies are less conclusive, in part due to the heterogeneous physiologic and psychosocial changes occurring over the course of development. The author thus concludes that psychiatrists can reduce risk in these special patient populations by creating safer environments in the form of changes in policy and increased support services. PMID:25924230

  12. The role of serotonin in impulsive aggression, suicide, and homicide in adolescents and adults: a literature review.

    PubMed

    Glick, Amy R

    2015-05-01

    This is a literature review discussing previous studies on the associations between impulsive aggression and the serotonergic system in adults, adolescents, and children. The review demonstrates that there is a clear association between low cerebrospinal fluid serotonin and impulsive aggression. However, studies on neurotransmitter receptor profiles, functional imaging, genetics, and epigenetics reviewed in this article suggest a more complicated picture that includes consideration of gene vs. environment in the evaluation of risk. Serotonin supplementation studies suggest that selective serotonin reuptake inhibitors may reduce impulsive aggression in some adults but are less effective in adults with pathological aggression and also in children and adolescents. Child and adolescent studies are less conclusive, in part due to the heterogeneous physiologic and psychosocial changes occurring over the course of development. The author thus concludes that psychiatrists can reduce risk in these special patient populations by creating safer environments in the form of changes in policy and increased support services.

  13. Micro hollow cathode discharges

    SciTech Connect

    Schoenbach, K.H.; Peterkin, F.E.; Verhappen, R.

    1995-12-31

    Hollow cathode discharges are glow discharges with the cathode fall and negative glow confined in a cavity in the cathode. For the discharge to develop, the cathode hole dimensions must be on the order of the mean free path. By reducing the cathode hole dimensions it is therefore possible to increase the pressure. Stable hollow cathode discharges in air have been observed at almost one atmosphere when the cathode diameter was reduced to 20 micrometers. In order to study the electrical parameters of a micro hollow cathode discharge, a set of experiments has been performed in argon at pressures in the torr range and a cathode hole diameter of 0.7 mm in molybdenum. The current-voltage characteristics and the appearance of the discharge plasma showed two distinct regions. At lower voltage or pressure the current varies linearly with voltage and the hollow cathode plasma is concentrated around the axis of the cathode hole (low glow mode). At higher values of voltage or pressure the current increases nonlinearly, up to a point where a transition into a low voltage hollow cathode arc was observed, and the plasma column expands and fills almost the entire cathode hole (high glow mode). Spectral measurements showed that the transition from the low glow mode into the high glow mode is related to an increased density of electrode vapor in the hollow cathode discharge. Up to the breakdown into a hollow cathode arc, the current voltage characteristic of the discharge has a positive slope. In this range, hollow cathode discharges can be operated in parallel without a ballast resistor.

  14. A consistent approach to estimate the breakdown voltage of high voltage electrodes under positive switching impulses

    NASA Astrophysics Data System (ADS)

    Arevalo, L.; Wu, D.; Jacobson, B.

    2013-08-01

    The main propose of this paper is to present a physical model of long air gap electrical discharges under positive switching impulses. The development and progression of discharges in long air gaps are attributable to two intertwined physical phenomena, namely, the leader channel and the streamer zone. Experimental studies have been used to develop empirical and physical models capable to represent the streamer zone and the leader channel. The empirical ones have led to improvements in the electrical design of high voltage apparatus and insulation distances, but they cannot take into account factors associated with fundamental physics and/or the behavior of materials. The physical models have been used to describe and understand the discharge phenomena of laboratory and lightning discharges. However, because of the complex simulations necessary to reproduce real cases, they are not in widespread use in the engineering of practical applications. Hence, the aim of the work presented here is to develop a model based on physics of the discharge capable to validate and complement the existing engineering models. The model presented here proposes a new geometrical approximation for the representation of the streamer and the calculation of the accumulated electrical charge. The model considers a variable streamer region that changes with the temporal and spatial variations of the electric field. The leader channel is modeled using the non local thermo-equilibrium equations. Furthermore, statistical delays before the inception of the first corona, and random distributions to represent the tortuous nature of the path taken by the leader channel were included based on the behavior observed in experimental tests, with the intention of ensuring the discharge behaved in a realistic manner. For comparison purposes, two different gap configurations were simulated. A reasonable agreement was found between the physical model and the experimental test results.

  15. Striatal dopamine D₂/D₃ receptor binding in pathological gambling is correlated with mood-related impulsivity.

    PubMed

    Clark, Luke; Stokes, Paul R; Wu, Kit; Michalczuk, Rosanna; Benecke, Aaf; Watson, Ben J; Egerton, Alice; Piccini, Paola; Nutt, David J; Bowden-Jones, Henrietta; Lingford-Hughes, Anne R

    2012-10-15

    Pathological gambling (PG) is a behavioural addiction associated with elevated impulsivity and suspected dopamine dysregulation. Reduced striatal dopamine D(2)/D(3) receptor availability has been reported in drug addiction, and may constitute a premorbid vulnerability marker for addictive disorders. The aim of the present study was to assess striatal dopamine D(2)/D(3) receptor availability in PG, and its association with trait impulsivity. Males with PG (n=9) and male healthy controls (n=9) underwent [11C]-raclopride positron emission tomography imaging and completed the UPPS-P impulsivity scale. There was no significant difference between groups in striatal dopamine D(2)/D(3) receptor availability, in contrast to previous reports in drug addiction. However, mood-related impulsivity ('Urgency') was negatively correlated with [11C]-raclopride binding potentials in the PG group. The absence of a group difference in striatal dopamine binding implies a distinction between behavioural addictions and drug addictions. Nevertheless, our data indicate heterogeneity in dopamine receptor availability in disordered gambling, such that individuals with high mood-related impulsivity may show differential benefits from dopamine-based medications. PMID:22776462

  16. Dynamical relations for left ventricular ejection - Flow rate, momentum, force and impulse

    NASA Technical Reports Server (NTRS)

    Back, L. H.; Selzer, R. H.; Gordon, D. G.; Ledbetter, D. C.; Crawford, D. W.

    1984-01-01

    An investigation was carried out to quantitatively evaluate left ventricular volume flow rate, momentum, force and impulse derived from application of conservation principles for mass and momentum of blood within the ventricle during the ejection phase. An automated digital image processing system was developed and applied to left ventricular angiograms which are computer processed and analyzed frame by frame to determine the dynamical relations by numerical methods. The initial experience with force and impulse has indicated that neither quantity seemed to be a sensitive indicator of coronary artery disease as evaluated by qualitative angiography for the particular patient group studied. Utilization of the dynamical relations in evaluating human left ventricular performance requires improved means of measurement and interpretation of clinical studies.

  17. Glow discharge detector

    DOEpatents

    Koo, Jackson C.; Yu, Conrad M.

    2002-01-01

    A highly sensitive electronic ion cell for the measurement of trace elements in He carrier gas which involves glow discharge. A constant wave (CW) glow discharge detector which is controlled through a biased resistor, can detect the change of electron density caused by impurities in the He carrier gas by many orders of magnitude larger than that caused by direct ionization or electron capture. The glow discharge detector utilizes a floating pseudo-electrode to form a probe in or near the plasma. By using this probe, the large variation of electron density due to trace amounts of impurities can be directly measured.

  18. Discharge lamp technologies

    NASA Technical Reports Server (NTRS)

    Dakin, James

    1994-01-01

    This talk is an overview of discharge lamp technology commonly employed in general lighting, with emphasis on issues pertinent to lighting for plant growth. Since the audience is primarily from the plant growth community, and this begins the light source part of the program, we will start with a brief description of the discharge lamps. Challenges of economics and of thermal management make lamp efficiency a prime concern in controlled environment agriculture, so we will emphasize science considerations relating to discharge lamp efficiency. We will then look at the spectra and ratings of some representative lighting products, and conclude with a discussion of technological advances.

  19. INTENSE ENERGETIC GAS DISCHARGE

    DOEpatents

    Luce, J.S.

    1960-03-01

    A method and apparatus for initiating and sustaining an energetic gas arc discharge are described. A hollow cathode and a hollow anode are provided. By regulating the rate of gas flow into the interior of the cathode, the arc discharge is caused to run from the inner surface of the cathode with the result that adequate space-charge neutralization is provided inside the cathode but not in the main arc volume. Thus, the gas fed to the cathode is substantially completely ionized before it leaves the cathode, with the result that an energetic arc discharge can be maintained at lower operating pressures.

  20. 33 CFR 183.586 - Pressure impulse test.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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

  1. Choice Impulsivity: Definitions, Measurement Issues, and Clinical Implications

    PubMed Central

    Hamilton, Kristen R.; Mitchell, Marci R.; Wing, Victoria C.; Balodis, Iris M.; Bickel, Warren K.; Fillmore, Mark; Lane, Scott D.; Lejuez, C. W.; Littlefield, Andrew K.; Luijten, Maartje; Mathias, Charles W.; Mitchell, Suzanne H.; Napier, T. Celeste; Reynolds, Brady; Schütz, Christian G.; Setlow, Barry; Sher, Kenneth J.; Swann, Alan C.; Tedford, Stephanie E.; White, Melanie J.; Winstanley, Catharine A.; Yi, Richard; Potenza, Marc N.; Moeller, F. Gerard

    2015-01-01

    Background Impulsivity critically relates to many psychiatric disorders. Given the multi-faceted construct that impulsivity represents, defining core aspects of impulsivity is vital for the assessment and understanding of clinical conditions. Choice impulsivity (CI), involving the preferential selection of smaller sooner rewards over larger later rewards, represents one important type of impulsivity. Method The International Society for Research on Impulsivity (InSRI) convened to discuss the definition and assessment of CI and provide recommendations regarding measurement across species. Results Commonly used preclinical and clinical CI behavioral tasks are described, and considerations for each task are provided to guide CI task selection. Differences in assessment of CI (self-report, behavioral) and calculating CI indices (e.g., area-under-the-curve, indifference point, steepness of discounting curve) are discussed along with properties of specific behavioral tasks used in preclinical and clinical settings. Conclusions The InSRI group recommends inclusion of measures of CI in human studies examining impulsivity. Animal studies examining impulsivity should also include assessments of CI and these measures should be harmonized in accordance with human studies of the disorders being modeled in the preclinical investigations. The choice of specific CI measures to be included should be based on the goals of the study and existing preclinical and clinical literature using established CI measures. PMID:25867841

  2. Validity of proposed DSM-5 ADHD impulsivity symptoms in children.

    PubMed

    Ünsel Bolat, Gül; Ercan, Eyüp Sabri; Salum, Giovanni Abrahão; Bilaç, Öznur; Massuti, Rafael; Uysal Özaslan, Taciser; Bolat, Hilmi; Rohde, Luis Augusto

    2016-10-01

    The American Psychiatric Association (APA) working group on Attention-Deficit/Hyperactivity Disorder (ADHD) proposed the inclusion of four new impulsivity symptoms. However, they were not included in DSM-5 due to the lack of sufficient evidence. The aim of this study is to investigate the performance of the proposed four ADHD impulsivity symptoms with respect to: (a) ADHD factor structure; (b) performance in predicting clinical impairment; (c) specificity for ADHD diagnosis and (d) best symptomatic threshold to predict clinical impairment. The sample comprised 416 children (31 ADHD subjects according to both DSM-IV and proposed DSM-5, 20 ADHD subjects according to just one diagnostic system and 365 controls) from 12 schools. Diagnoses were derived using semi-structured interviews and ADHD rating scales. Results from confirmatory factor analysis indicate that addition of the four new impulsivity items provided a slightly better factor structure if compared to models including only 18 items. Regression analyses showed that only one of the new impulsivity symptoms (impatient) was part of the list of best predictors of impairment. None of the four new impulsivity items was specifically associated with ADHD diagnosis. The best cutoff point in the hyperactivity/impulsivity dimension for predicting impairment did not change significantly. Overall, our findings suggest that the determination on how to best capture impulsivity dimension as part of the ADHD construct needs more investigation and that there is not enough evidence to include these four assessed impulsivity symptoms as part of the ADHD criteria.

  3. Impulsivity in internet addiction: a comparison with pathological gambling.

    PubMed

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

    2012-07-01

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

  4. Impulsivity, Coping, Stress, and Problem Gambling among University Students

    ERIC Educational Resources Information Center

    Lightsey, Owen Richard, Jr.; Hulsey, C. Duncan

    2002-01-01

    The authors investigated whether coping styles moderated the relationship between (a) impulsivity and stress and (b) stress and gambling behavior and tested whether impulsive persons who use avoidant or emotion-focused coping under high-stress conditions are most likely to gamble. Among 202 university student volunteers, 33% of men but only 3% of…

  5. Temperament and Character Dimensions: Correlates of Impulsivity in Morphine Addicts

    PubMed Central

    Abassi, Moslem; Abolghasemi, Abbas

    2015-01-01

    Background: Given the role of temperament and character dimensions on impulsivity in addicts, the purpose of this study was to temperament and character dimensions: correlates of impulsivity in morphine addicts. Objectives: The aim of this study was to determine and verify the association of temperament and character dimensions with impulsivity in morphine addicts. Patients and Methods: The research method was descriptive and correlational. The study sample consisted of 120 morphine addicts referred to drug addiction treatment centers in Ardabil city in 2013. The participants were selected through convenience sampling method from 5 centers. We used impulsivity scale as well as temperament and character inventory to collect data. Results: The results showed that significant relationship existed between impulsivity and characteristics such as novelty seeking, harm avoidance, reward dependence, persistence, self-directedness, and cooperativeness, while no significant relationship between impulsivity and self-transcendence was observed. The results of the multiple regression analysis showed that 47% of the impulsivity variance was explained by temperament and character dimensions. Conclusions: These findings suggest that temperament and character dimensions are associated with impulsivity. The findings also have important implications for prevention, pathology, and treatment in the morphine addicts. PMID:26870706

  6. Angular Impulse and Balance Regulation During the Golf Swing.

    PubMed

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

    2016-08-01

    Our aim was to determine how skilled players regulate linear and angular impulse while maintaining balance during the golf swing. Eleven highly-skilled golf players performed swings with a 6-iron and driver. Components contributing to linear and angular impulse generated by the rear and target legs (resultant horizontal reaction force [RFh], RFh-angle, and moment arm) were quantified and compared across the group and within a player (α = .05). Net angular impulse generated by both the rear and target legs was greater for the driver than the 6-iron. Mechanisms used to regulate angular impulse generation between clubs varied across players and required coordination between the legs. Increases in net angular impulse with a driver involved increases in target leg RFh. Rear leg RFh-angle was maintained between clubs whereas target leg RFh became more aligned with the target line. Net linear impulse perpendicular to the target line remained near zero, preserving balance, while net linear impulse along the target line decreased in magnitude. These results indicate that the net angular impulse was regulated between clubs by coordinating force generation of the rear and target legs while sustaining balance throughout the task. PMID:26958870

  7. Sex Differences in Impulsivity: A Meta-Analysis

    ERIC Educational Resources Information Center

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

    2011-01-01

    Men are overrepresented in socially problematic behaviors, such as aggression and criminal behavior, which have been linked to impulsivity. Our review of impulsivity is organized around the tripartite theoretical distinction between reward hypersensitivity, punishment hyposensitivity, and inadequate effortful control. Drawing on evolutionary,…

  8. The effects of heroin administration and drug cues on impulsivity.

    PubMed

    Jones, Jermaine D; Vadhan, Nehal P; Luba, Rachel R; Comer, Sandra D

    2016-08-01

    Drug addiction is a chronic relapsing disorder characterized by compulsive drug seeking and continued use despite negative consequences. Behavioral impulsivity is a strong predictor of the initiation and maintenance of drug addiction. Preclinical data suggest that heroin may exacerbate impulsive characteristics in an individual but this has yet to be assessed in clinical samples. The current secondary data analysis sought to investigate the effects of heroin on impulsivity along with the effects of exposure to drug cues. Using the current data set, we also tentatively assessed the etiological relationship between impulsivity and heroin abuse. Sixteen heroin-dependent participants were recruited to complete Immediate Memory Task/Delayed Memory Task (IMT/DMT) and GoStop tasks following repeated heroin administration, following acute heroin administration, and following a drug cue exposure session. Four preceding days of active heroin availability, compared to four preceding days of placebo drug availability, increased impulsivity assessed using the IMT and DMT. Presentation of drug cues similarly acted to increase impulsivity assessments on all three tasks. It also appears that heavier users were more susceptible to the influence of drug cues on impulsivity. The present study represents a step toward a more comprehensive understanding of the interaction between opioid abuse and impulsivity. A better understanding of these factors could provide critical insight into the maintenance of heroin use and relapse. PMID:27062912

  9. Individual Differences in Impulsive Choice and Timing in Rats

    ERIC Educational Resources Information Center

    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…

  10. Spectral analysis of impulse noise for hearing conservation purposes

    SciTech Connect

    Stevin, G.O.

    1982-12-01

    Damage-risk criteria for impulse noise does not presently take the spectrum of the impulse into account; however, it is known that the human auditory system is spectrally tuned. The present paper advocates the extension to impulse noise of the noise dose concept which is widely used for continuous noise. This approach is based upon sound exposure instead of sound pressure. An A-weighting filter or an octave band analysis can then be used to take the spectral content of the impulses into account. The equipment needed for applying these procedures for impulse noise is an integrating sound level meter or a digital Fourier processor. Generalized spectral methods have been evaluated by means of an impulse simulation applied to a mathematical model of the human hearing mechanism. The results of this simulation agree with the most recent experiments on impulse noise and fully support the proposed rating methods. This conclusion must be emphasized as it leads the derivation of a uniform procedure for predicting loudness and damage risk for hearing which is applicable for continuous noise as well as for impulse noise.

  11. Spectral analysis of impulse noise for hearing conservation purposes.

    PubMed

    Stevin, G O

    1982-12-01

    Damage-risk criteria for impulse noise does not presently take the spectrum of the impulse into account; however, it is known that the human auditory system is spectrally tuned. The present paper advocates the extension to impulse noise of the noise dose concept which is widely used for continuous noise. This approach is based upon sound exposure instead of sound pressure. An A-weighting filter or an octave band analysis can then be used to take the spectral content of the impulses into account. The equipment needed for applying these procedures for impulse noise is an integrating sound level meter or a digital Fourier processor. Generalized spectral methods have been evaluated by means of an impulse simulation applied to a mathematical model of the human hearing mechanism. The results of this simulation agree with the most recent experiments on impulse noise and fully support the proposed rating methods. This conclusion must be emphasized as it leads the derivation of a uniform procedure for predicting loudness and damage risk for hearing which is applicable for continuous noise as well as for impulse noise.

  12. Two-meter laser material response impulse measurements

    NASA Astrophysics Data System (ADS)

    Robertson, Karin; Cates, Michael C.

    1988-02-01

    Impulse generated by Excimer Laser Target interactions has been extensively studied at Maxwell Labs. Inc. Results are presented of impulse measurements on aluminum targets using the SDIO/MLI Two Meter Laser operating with KrF as the lasing media. The results of previous MLI impulse measurements using XeF laser media are summarized. The work presented was motivated by earlier impulse measurements also taken on the Two Meter Laser. The data showed much higher impulse to energy ratios than predicted. Additionally, work done elsewhere gave lower I/E values than those found at MLI. The initial MLI impulse studies used a Fotonic gauge as a velocity sensor. As a check on its accuracy, impulse was measured using a simple pendulum; the results agreed with the Fotonic gauge data. A careful investigation of the pendulum experimental technique followed; no problem were found. The S-Cubed ZOOS code was also examined. It is a 1 and 1/2-D code, and only accounts for impulse delivered under the Laser footprint. Additional momentum, however, is provided outside the laser spot via the plasma cloud that results from the laser target interaction.

  13. Domain-Specific Impulsivity in School-Age Children

    ERIC Educational Resources Information Center

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

    2013-01-01

    Impulsivity is a salient individual difference in children with well-established predictive validity for life outcomes. The current investigation proposes that impulsive behaviors vary systematically by domain. In a series of studies with ethnically and socioeconomically diverse samples of middle school students, we find that schoolwork-related…

  14. Optimum Three Impulse Trajectory Generator with Patched Conic Trajectory Model

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

    Optimal multi-impulse trajectories were investigated as a nominal about which asymptotic expansion was used to obtain approximations of optimal low thrust trajectories. The work consisted of the analysis and description of an optimal 3-impulse trajectory program. A patched-conic trajectory model was specifically designed for compatibility with the subsequent addition of the low thrust expansion approximation.

  15. Individual differences in impulsivity predict anticipatory eye movements.

    PubMed

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

    2011-01-01

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

  16. Optimal impulsive trajectories for orbital rendezvous between elliptic orbits

    NASA Astrophysics Data System (ADS)

    Cheng, Ching-Wei

    1992-01-01

    This study uses and extends primer vector theory to obtain a minimum-fuel two or multiple impulse solution for co-planar and non co-planar elliptic-to-elliptic, time-fixed rendezvous. Lawden's conditions for an optimal impulsive trajectory and three additional methods to improve the non-optimal multiple impulse are introduced. To extend a 3-Impulse differential cost function provided by Jezewski and Rozendaal, the general differential cost function for an N-Impulse trajectory is developed. This approach defines the gradient vector for any set of boundary conditions. To determine the number of impulses, times, and locations for multiple-impulse optimal trajectories automatically, a computer program is developed. This software has been thoroughly tested in a wide variety of rendezvous situations. The singularity for a transfer angle of 180 degrees and the singular case of sin I = 0 are also accounted for in the program. Part of this work was accomplished using the Generalized Reduced Gradient method using its associated GRG2 computer code. The effects of inclination between the vehicle and target orbits, the initial positions of the vehicle and target, and the direction of the major axes are considered. Numerical results for several different orbit configurations are produced and discussed. The results are compared with the Hohmann/Hohmann type transfer and/or the optimal, finite, three-impulse transfer.

  17. The Impulse Energy of the TLE-associated Lightning

    NASA Astrophysics Data System (ADS)

    Chen, A. B.; Hsu, R.; Su, H.

    2013-12-01

    So far, the major types of the transient luminous events (TLEs) including sprites, halo and elves are believed to be directly triggered by cloud-to-ground lightning. Several models have been proposed to illustrate the detail physical process of these discharge phenomena. In general, the intense lightning with high peak current or charge moment change seems to have a higher production efficiency, but not statistically investigated yet. The ISUAL experiment has globally collected more than 20,000 TLEs since 2009, and they are all well classified and geographically located. We cross identified the ISUAL TLEs with the revised database of the World Wide Lightning Location Network (WWLLN) to find the impulse energies of the coincident TLEs. The median energies of the strokes for the elve, sprite, and halo are 12563.7 J, 6975.48 J and 11879.5 J respectively, significantly higher than the global median stroke energy of 629 J observed by WWLLN in 2010 [Hutchins et al., 2013]. Furthermore, the energy distributions of the oceanic and land elves are almost identical which is quite different with the energy distribution of lightning. These results directly confirm that the TLEs are triggered by the intense lightning at least above the average level. The global lightning density with different energies are also constructed to compare with the geolocation of ISUAL-recorded elves. The results show the elves congregate over the hot zones of the most energetic lightning and have the same latitudinal variation over different seasons. Elves are not captured in some regions with strong activity of energetic lightning, and these regions located behind the earth limb while ISUAL observes. Since they are revealed to be observable by ISUAL but faint and distant events are greatly blocked by the earth limb or the atmosphere. It implies the global occurrence rate reported by the previous studies may be lower at least a factor of 2 or 3.

  18. [MR-galactography: a new way to explore nipple discharges].

    PubMed

    Berment, H; Dolores, M; Genevois, A; Dacher, J-N

    2011-05-01

    Nipple discharge is a common breast complaint that justifies an etiologic check-up in order to identify and characterize the underlying intraductal lesion. The low sensitivity and specificity of the existing imaging exams led to the search of new, more efficient ways to explore nipple discharge. MR-Galactography is one of these emerging techniques. Recent literature tends to prove that MR-Galactography could be an interesting technique for localizing and characterizing lesions causing nipple discharge. PMID:21514201

  19. Diffusion cannot govern the discharge of neurotransmitter in fast synapses.

    PubMed Central

    Khanin, R; Parnas, H; Segel, L

    1994-01-01

    In the present work we show that diffusion cannot provide the observed fast discharge of neurotransmitter from a synaptic vesicle during neurotransmitter release, mainly because it is not sufficiently rapid nor is it sufficiently temperature-dependent. Modeling the discharge from the vesicle into the cleft as a continuous point source, we have determined that discharge should occur in 50-75 microseconds, to provide the observed high concentrations of transmitter at the critical zone. Images FIGURE 5 PMID:7811953

  20. [MR-galactography: a new way to explore nipple discharges].

    PubMed

    Berment, H; Dolores, M; Genevois, A; Dacher, J-N

    2011-05-01

    Nipple discharge is a common breast complaint that justifies an etiologic check-up in order to identify and characterize the underlying intraductal lesion. The low sensitivity and specificity of the existing imaging exams led to the search of new, more efficient ways to explore nipple discharge. MR-Galactography is one of these emerging techniques. Recent literature tends to prove that MR-Galactography could be an interesting technique for localizing and characterizing lesions causing nipple discharge.

  1. Impulsivity and Parkinson’s disease: More than just disinhibition☆

    PubMed Central

    Antonelli, Francesca; Ray, Nicola; Strafella, Antonio P.

    2012-01-01

    In the last few years it has become clear that impulsivity is a complex behaviour composed of different domains and dependent on different neural networks. The proposed pathogenetic mechanisms for the emergence of impulsivity disorders in Parkinson’s Disease (PD) can be broadly separated into three potentially interacting processes: the contribution of premorbid susceptibility to impulsivity, the contribution of the disease itself to the behaviour and the potential contribution of therapeutic agents. Growing evidence suggests that dopamine and the subthalamic nucleus are playing a certain role in the pathophysiology of different aspects of impulsivity. In this review, we summarise the main concepts defining various components of impulsivity both in healthy subjects and patients affected by PD. PMID:21683964

  2. Demonstration scheme for impulse response of various systems

    NASA Astrophysics Data System (ADS)

    Qadir, Abdul; Ali, Aamir

    2013-03-01

    In linear system theory impulse response of any system is of great significance. It is the impulse response which is helpful in determining the convolution in continuous time system (unit sample response in Digital Signal Processing). The impulse response of simple systems can be calculated from the system differential equation or from the transfer function of the system (by taking the inverse Fourier Transform of transfer function). To the best of author's knowledge there exists no such scheme in the literature so far showing any practical method that can demonstrate the impulse response of a system on the oscilloscope. In this paper the method of demonstrating the impulse response of any linear system to the undergraduate students is presented. The approach is simple and is developed with minimum component count.

  3. Impulsive Pressurization of Neuronal Cells for Traumatic Brain Injury Study

    PubMed Central

    Feng, Ruqiang; Lim, Jung Yul

    2011-01-01

    A novel impulsive cell pressurization experiment has been developed using a Kolsky bar device to investigate blast-induced traumatic brain injury (TBI). We demonstrate in this video article how blast TBI-relevant impulsive pressurization is applied to the neuronal cells in vitro. This is achieved by using well-controlled pressure pulse created by a specialized Kolsky bar device, with complete pressure history within the cell pressurization chamber recorded. Pressurized neuronal cells are inspected immediately after pressurization, or further incubated to examine the long-term effects of impulsive pressurization on neurite/axonal outgrowth, neuronal gene expression, apoptosis, etc. We observed that impulsive pressurization at about 2 MPa induces distinct neurite loss relative to unpressurized cells. Our technique provides a novel method to investigate the molecular/cellular mechanisms of blast TBI, via impulsive pressurization of brain cells at well-controlled pressure magnitude and duration. PMID:22005926

  4. A systematic review of impulsivity in eating disorders.

    PubMed

    Waxman, Samantha E

    2009-11-01

    The purpose of this paper is to conduct a systematic review of the current literature that examines impulsivity in individuals with eating disorders (ED). Studies were obtained from Embase, Pubmed and Psycinfo, and were included if they assessed impulsivity in individuals over 18 years of age with an ED diagnosis and published in the last 10 years. The methodological quality of the studies was rated. Twelve studies were included in this review, with methodological quality varying across studies. Findings suggest that impulsivity is best assessed multi-modally, with a combination of self-report, behavioural and physiological measures. In general, impulsivity was found to differentiate individuals with EDs from controls, as well as across diagnostic subtypes. The current findings have important clinical implications for our understanding and treatment of both impulsivity and eating disorders.

  5. 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

  6. Brain radiation - discharge

    MedlinePlus

    Radiation - brain - discharge; Cancer-brain radiation; Lymphoma - brain radiation; Leukemia - brain radiation ... Decadron) while you are getting radiation to the brain. It may make you hungrier, cause leg swelling ...

  7. Chest radiation - discharge

    MedlinePlus

    Radiation - chest - discharge; Cancer - chest radiation; Lymphoma - chest radiation ... When you have radiation treatment for cancer, your body goes through changes. About 2 weeks after your first treatment: It may be hard ...

  8. Eye muscle repair - discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000111.htm Eye muscle repair - discharge To use the sharing features on ... enable JavaScript. You or your child had eye muscle repair surgery to correct eye muscle problems that ...

  9. Capacitor discharge pulse analysis.

    SciTech Connect

    Baker, Michael Sean; Griffiths, Stewart K.; Tanner, Danelle Mary

    2013-08-01

    Capacitors used in firing sets and other high discharge current applications are discharge tested to verify performance of the capacitor against the application requirements. Parameters such as capacitance, inductance, rise time, pulse width, peak current and current reversal must be verified to ensure that the capacitor will meet the application needs. This report summarizes an analysis performed on the discharge current data to extract these parameters by fitting a second-order system model to the discharge data and using this fit to determine the resulting performance metrics. Details of the theory and implementation are presented. Using the best-fit second-order system model to extract these metrics results in less sensitivity to noise in the measured data and allows for direct extraction of the total series resistance, inductance, and capacitance.

  10. An experimental investigation of pulsed multichannel discharge across solid insulators

    NASA Technical Reports Server (NTRS)

    Lakdawala, V. K.; Ko, S. T.; Lee, J. H.

    1985-01-01

    An experimental study of pulsed surface flashover across a solid insulator in a vacuum is reported, with application of fast impulse voltages of a few tens of ns rise time and a few microsec tail time. Following the flashover voltage experiments, no visible degradation of the surface was found for the BaTiO3 sample, whereas for the TiO2 sample a distinct track mark could be seen where the flashover occurred. Three schemes for obtaining multichannel discharges were studied for plexiglass specimens, and results showed the number of shots to decrease as the number of channels increased.

  11. Discharges for lighting

    NASA Astrophysics Data System (ADS)

    Stoffels, W. W.; Nimalasuriya, T.; Flikweert, A. J.; Mulders, H. C. J.

    2007-12-01

    The most common man-made discharge is a lamp. Even though lamps are often considered a mature technology, the discharge physics is often poorly understood. Two recent initiatives discussed here show that plasma research can help to make significant improvements. First we discuss color separation in metal halide lamps, which is a problem that prevents these highly efficient lamps from being used in more applications. Secondly a novel lamp concept is presented that may replace the current mercury based fluorescent lamps.

  12. Impulse oscillometry: interpretation and practical applications.

    PubMed

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

    2014-09-01

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

  13. On coating adhesion during impulse plasma deposition

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    The impulse plasma deposition (IPD) technique is the only method of plasma surface engineering (among plasma-based technologies) that allows a synthesis of layers upon a cold unheated substrate and which ensures a good adhesion. This paper presents a study of plasma impacts upon a copper substrate surface during the IPD process. The substrate was exposed to pulsed N2/Al plasma streams during the synthesis of AlN layers. For plasma-material interaction diagnostics, the optical emission spectroscopy method was used. Our results show that interactions of plasma lead to sputtering of the substrate material. It seems that the obtained adhesion of the layers is the result of a complex surface mechanism combined with the effects of pulsed plasma energy impacts upon the unheated substrate. An example of such a result is the value of the critical load for the Al2O3 layer, which was measured by the scratch-test method to be above 40 N.

  14. Impulsive solar X-ray bursts

    NASA Technical Reports Server (NTRS)

    Crannell, C. J.; Frost, K. J.; Maetzler, C.; Ohki, K.; Saba, J. L.

    1977-01-01

    A set of 22 simple, impulsive solar flares, identified in the OSO-5 hard X-ray data, were analyzed together with coincident microwave and meterwave radio observations. The rise times and fall times of the X-ray bursts are found to be highly correlated and effectively equal, strongly suggesting a flare energizing mechanism that is reversible. The good time resolution available for these observations reveals that the microwave emission is influenced by an additional process, evident in the tendency of the microwave emission to peak later and decay more slowly than the symmetric X-ray bursts. Meterwave emission is observed in coincidence with the 5 events which show the strongest time correlation between the X-ray and microwave burst structure. This meterwave emission is characterized by U-burst radiation, indicating confinement of the flare source.

  15. Walking Through the Impulse-Momentum Theorem

    NASA Astrophysics Data System (ADS)

    Haugland, Ole Anton

    2013-02-01

    Modern force platforms are handy tools for investigating forces during human motion. Earlier they were very expensive and were mostly used in research laboratories. But now even platforms that can measure in two directions are quite affordable. In this work we used the PASCO 2-Axis Force Platform. The analysis of the data can serve as a nice illustration of qualitative or quantitative use of the impulse-momentum theorem p - p0 = ∫t0t Fdt = I. The most common use of force platforms is to study the force from the base during the push-off period of a vertical jump. I think this is an activity of great value, and I would recommend it. The use of force platforms in teaching is well documented in research literature.1-4

  16. Impulsivity, risky behaviors and accidents in alcohol-dependent patients

    PubMed Central

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

    2013-01-01

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

  17. Impulsivity and Attention Deficit-Hyperactivity Disorder: Subtype Classification Using the UPPS Impulsive Behavior Scale.

    PubMed

    Miller, Drew J; Derefinko, Karen J; Lynam, Donald R; Milich, Richard; Fillmore, Mark T

    2010-09-01

    This study examined the classification accuracy of the UPPS Impulsive Behavior Scale (UPPS) in discriminating several attention deficit/hyperactivity disorder (ADHD) subtypes, including predominantly inattentive type (ADHD/I), combined type (ADHD/C), and combined type with behavioral problems (ADHD/ODD), between each other and a non-ADHD control group using logistic regression analyses. The sample consisted of 88 children ranging in age from 9.0 years to 12.8 years, with a mean of 10.9 years. Children were predominantly male (74%) and Caucasian (86%) and in grades 3-7. Results indicated that the UPPS performed well in classifying ADHD subtypes relative to traditional diagnostic measures. In addition, analyses indicated that differences in symptoms between subtypes can be explained by specific pathways to impulsivity. Implications for the assessment of ADHD and conceptual issues are discussed. PMID:21765593

  18. Stimulation of the Subthalamic Nucleus and Impulsivity

    PubMed Central

    Ballanger, Benedicte; van Eimeren, Thilo; Moro, Elena; Lozano, Andres M.; Hamani, Clement; Boulinguez, Philippe; Pellecchia, Giovanna; Houle, Sylvain; Poon, Yu Yan; Lang, Anthony E.; Strafella, Antonio P.

    2010-01-01

    Objective In Parkinson disease (PD) patients, deep brain stimulation (DBS) of the subthalamic nucleus (STN) may contribute to certain impulsive behavior during high-conflict decisions. A neurocomputational model of the basal ganglia has recently been proposed that suggests this behavioral aspect may be related to the role played by the STN in relaying a “hold your horses” signal intended to allow more time to settle on the best option. The aim of the present study was 2-fold: 1) to extend these observations by providing evidence that the STN may influence and prevent the execution of any response even during low-conflict decisions; and 2) to identify the neural correlates of this effect. Methods We measured regional cerebral blood flow during a Go/NoGo and a control (Go) task to study the motor improvement and response inhibition deficits associated with STN-DBS in patients with PD. Results Although it improved Unified Parkinson Disease Rating Scale motor ratings and induced a global decrease in reaction time during task performance, STN-DBS impaired response inhibition, as revealed by an increase in commission errors in NoGo trials. These behavioral effects were accompanied by changes in synaptic activity consisting of a reduced activation in the cortical networks responsible for reactive and proactive response inhibition. Interpretation The present results suggest that although it improves motor functions in PD patients, modulation of STN hyperactivity with DBS may tend at the same time to favor the appearance of impulsive behavior by acting on the gating mechanism involved in response initiation. PMID:20035509

  19. Ionospheric current contribution to the main impulse of a negative sudden impulse

    NASA Astrophysics Data System (ADS)

    Vichare, Geeta; Rawat, Rahul; Bhaskar, Ankush; Pathan, Bashir M.

    2014-12-01

    The geomagnetic field response to a moderate-amplitude negative sudden impulse (SI-) that occurred on 14 May 2009 at 10:30 UT was examined at 97 geomagnetic observatories situated all over the globe. The response signature contains a contribution from magnetospheric as well as ionospheric currents. The main impulse (MI) is defined as the maximum depression in the observed geomagnetic field. It is observed that for low-to-high latitudes, the amplitude of the MI is larger in the afternoon to post-dusk sector than in the dawn-noon sector, indicating asymmetry in the MI amplitude. We estimated the contribution at various observatories due to the Chapman-Ferraro magnetopause currents using the Tsyganenko model (T01) and subtracted this from the observed MI amplitude to obtain the contribution due to ionospheric currents. It is found that the ionospheric currents contribute significantly to the MI amplitude of moderate SI- even at low-to-mid latitudes and that the contribution is in the same direction as that from the magnetopause currents near dusk and in the opposite direction near dawn. The equivalent current vectors reveal a clockwise (anticlockwise) ionospheric current loop in the afternoon (morning) sector during the MI of the negative pressure impulse. This evidences an ionospheric twin-cell-vortex current system (DP2) due to field-aligned currents (FACs) associated with the dusk-to-dawn convection electric field during the MI of an SI-. We also estimated the magnetic field variation due to prompt penetration electric fields, which is found to be very small at low latitudes in the present case. The studied SI- is not associated with shock, and hence no preliminary reverse impulse was evident. In addition, the summer hemisphere reveals larger MI amplitudes than the winter hemisphere, indicating once again the role of ionospheric currents.

  20. Relations Between Trait Impulsivity, Behavioral Impulsivity, Physiological Arousal, and Risky Sexual Behavior among Young Men

    PubMed Central

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

    2014-01-01

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

  1. Optical Emission Spectroscopy of Microplasma Discharge in Sea Water

    NASA Astrophysics Data System (ADS)

    Gamaleev, Vladislav; Hatta, Akimitsu; Furuta, Hiroshi; Oh, Jun-Seok; Okamura, Yo; Kitamura, Kensuke; Hashimoto, Yusuke

    2015-09-01

    We have been investigating microplasma discharge in sea water for optical emission spectroscopy. Microplasma discharge in artificial sea water (10ASW) was carried using needle-to-plane platinum electrode system. The gap, between electrodes, was ranged from 10 to 60 microns. The electricity source was impulse generatorwith MOSFET switch and variable capacitance and inductance. The maximum voltage and current for this scheme were respectively 1 kV and 10 A, pulse width 10 μs. It has been confirmed that, using the micro-gap configuration, spark discharges were ignited at the conventional breakdown voltages below 1kV, even in the conductive sea water. Was noted formation of small bubbles before of the plasma ignition process. The mechanism of formation of these bubbles is mostly Joule heating because of high currents. It has been speculated that plasma discharge initiates in bubbles. Optical emission spectroscopy of microplasma in sea water was carried. In the spectra, emission peaks for H, O, Na, Mg, Ca, Cl and Pt were clearly detected. Besides the main components of 10ASW, contaminants from the electrodes appeared in the spectra. The characteristics of microplasma discharge in sea water and analysis of the optical emission spectra will be presented. This work was supported by JSPS KAKENHI Grant Number 26600129. The ASW was provided from Prof. Kei Okamura of Kochi University.

  2. A BRIGHT IMPULSIVE SOLAR BURST DETECTED AT 30 THz

    SciTech Connect

    Kaufmann, P.; Fernandes, L. O. T.; Kudaka, A. S.; De Souza, R. V.; Valio, A.; Raulin, J.-P.; White, S. M.; Freeland, S. L.; Marcon, R.; Aballay, J. L.; Fernandez, G.; Godoy, R.; Marun, A.; Gimenez de Castro, C. G.

    2013-05-10

    Ground- and space-based observations of solar flares from radio wavelengths to gamma-rays have produced considerable insights but raised several unsolved controversies. The last unexplored wavelength frontier for solar flares is in the range of submillimeter and infrared wavelengths. Here we report the detection of an intense impulsive burst at 30 THz using a new imaging system. The 30 THz emission exhibited remarkable time coincidence with peaks observed at microwave, mm/submm, visible, EUV, and hard X-ray wavelengths. The emission location coincides with a very weak white-light feature, and is consistent with heating below the temperature minimum in the atmosphere. However, there are problems in attributing the heating to accelerated electrons. The peak 30 THz flux is several times larger than the usual microwave peak near 9 GHz, attributed to non-thermal electrons in the corona. The 30 THz emission could be consistent with an optically thick spectrum increasing from low to high frequencies. It might be part of the same spectral component found at sub-THz frequencies whose nature remains mysterious. Further observations at these wavelengths will provide a new window for flare studies.

  3. Causal Pathways Between Impulsiveness, Cocaine Use Consequences, and Depression

    PubMed Central

    Lister, Jamey J.; Ledgerwood, David M.; Lundahl, Leslie H.; Greenwald, Mark K.

    2014-01-01

    Aims The present study examined whether lifetime cocaine use consequences mediate the relationship between trait impulsiveness and current depression symptoms among regular cocaine users. Methods Regular cocaine users (N = 108) were assessed using: Barratt Impulsiveness Scale subscales (non-planning, attentional, motor sub-scales) to measure trait impulsiveness; a standardized Drug History and Use Questionnaire to measure cocaine use and related consequences; and Beck Depression Inventory to measure current depression symptoms. Results All impulsiveness subscales were positively associated with an earlier age of first cocaine use, a higher degree of current depression symptoms and a greater number of lifetime cocaine use consequences. In three separate simple mediation tests, lifetime cocaine use consequences partially mediated the relationship between each of the impulsiveness subscales (non-planning: R2 = .42; attentional: R2 = .40; motor: R2 = .24) and current depression symptoms. Separate moderated mediation analyses failed to demonstrate an interaction between lifetime cocaine use and cocaine-related consequences predicting depression symptoms for the mediation models. Conclusions Cocaine-related consequences function in a more nuanced manner than just an outcome of impulsiveness or cocaine use, but as a pathway between trait impulsiveness and current depression symptoms. PMID:25280245

  4. Method of reducing impulsive noise in electromagnetic geophysical data

    SciTech Connect

    Spies, B.R.

    1990-07-31

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

  5. Optimal N-impulse transfer between coplanar orbits

    NASA Astrophysics Data System (ADS)

    Broucke, Roger A.; Prado, Antonio F. B. A.

    1994-11-01

    In the present research we consider the problem of optimal (minimum delta V) time-free N-impulse transfers between any two coplanar orbits, for the cases where N is less than or equal to 4. For the two-impulse maneuver, we develop optimality conditions that lead to a non-linear system of three equations and three unknowns. The solution of this system gives us the bi-impulse transfer with minimum total delta V. For the three-impulse maneuver, we develop a new approach. We use two elliptic transfer orbits that are connected by a negligible impulse applied at an infinite distance from the main body. It is an extension of the bi-ellptic transfer, where the two orbits involved in the transfer are not co-axial. We study in detail and show regions of optimality for the most trivial cases of transfers: between two circular orbits; one circular and one elliptic orbit; two elliptic co-axial orbits. We complete the paper by developing a scheme to reduce the total delta V for some of those maneuvers, by adding a second impulse at infinity, and making it a four-impulse maneuver.

  6. Attenuation of high-level impulses by earmuffs.

    PubMed

    Zera, Jan; Mlynski, Rafal

    2007-10-01

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

  7. 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.

  8. Alexithymia, emotion dysregulation, impulsivity and aggression: A multiple mediation model.

    PubMed

    Velotti, Patrizia; Garofalo, Carlo; Petrocchi, Chiara; Cavallo, Francesca; Popolo, Raffaele; Dimaggio, Giancarlo

    2016-03-30

    There is a need to better understand the antecedent of aggressive behaviors in order to tailor treatments and reduce the associated damage to the others and the self. Possible mechanisms underlying aggression are poor emotional awareness and emotion dysregulation, as well as impulsivity. Here, we examined the relationships among alexithymia, emotion dysregulation, impulsivity and aggression, comparing a mixed psychiatric sample (N=257) and a community sample (N=617). The clinical sample reported greater levels of alexithymia, emotion dysregulation, trait impulsivity and aggression, than the community sample. Furthermore, in the community sample, emotion dysregulation and impulsivity mediated the relationship (i.e., accounted for the shared variance) between alexithymia and aggression. In the clinical sample, only emotion dysregulation explained the alexithymia-aggression link. In particular, specific dimensions of the emotion dysregulation (i.e., Negative Urgency) and impulsivity constructs (i.e., cognitive and motor impulsivity) played a unique role in explaining these associations. Finally, controlling for depressive symptoms reduced some of the findings involving impulsivity to nonsignificant results. Overall, our findings add to the extant literature attesting to the relevance of alexithymia and emotion dysregulation for understanding aggression, and providing concrete recommendation for the treatment and prevention of aggressive tendencies.

  9. 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.

  10. Negative emotion-driven impulsivity predicts substance dependence problems.

    PubMed

    Verdejo-García, Antonio; Bechara, Antoine; Recknor, Emily C; Pérez-García, Miguel

    2007-12-01

    Impulsivity is predominant among users of several drugs of abuse including alcohol, cocaine, and amphetamines, and it is considered a risk factor for later development of alcohol and substance abuse and dependence. However, there is little consensus on how impulsivity should be defined and measured, and there are few studies on the relationship between separate dimensions of impulsivity and substance dependence. We used a multidimensional measure of impulsivity (the UPPS scale) to examine differences between 36 individuals with substance dependence (ISD) and 36 drug-free controls on the dimensions of urgency, lack of premeditation, lack of perseverance, and sensation seeking. In addition, we examined which dimensions of impulsivity better predicted addiction-related problems as measured with the addiction severity index. Results revealed that ISD show high scores on dimensions of urgency, lack of perseverance, and lack of premeditation (effect sizes ranging from 1.10 to 1.96), but not on sensation seeking. Among the different impulsivity dimensions, urgency was the best predictor of severity of medical, employment, alcohol, drug, family/social, legal and psychiatric problems in ISD, explaining 13-48% of the total variance of these indices. Furthermore, urgency scores alone correctly classified 83% of the participants in the ISD group. Urgency is characterized by a tendency to act impulsively in response to negative emotional states. Thus, our results could have important implications for novel treatment approaches for substance dependence focused on emotional regulation. PMID:17629632

  11. Waiting Impulsivity: The Influence of Acute Methylphenidate and Feedback

    PubMed Central

    Chang-Webb, Yee Chien; Morris, Laurel S.; Cooper, Ella; Sethi, Arjun; Baek, Kwangyeol; Grant, Jon; Robbins, Trevor W.; Harrison, Neil A

    2016-01-01

    Background: The ability to wait and to weigh evidence is critical to behavioral regulation. These behaviors are known as waiting and reflection impulsivity. In Study 1, we examined the effects of methylphenidate, a dopamine and norepinephrine reuptake inhibitor, on waiting and reflection impulsivity in healthy young individuals. In study 2, we assessed the role of learning from feedback in disorders of addiction. Methods: We used the recently developed 4-Choice Serial Reaction Time task and the Beads task. Twenty-eight healthy volunteers were tested twice in a randomized, double-blind, placebo-controlled cross-over trial with 20mg methylphenidate. In the second study, we analyzed premature responses as a function of prior feedback in disorders of addiction. Results: Study 1: Methylphenidate was associated with greater waiting impulsivity to a cue predicting reward along with faster responding to target onset without a generalized effect on reaction time or attention. Methylphenidate influenced reflection impulsivity based on baseline impulsivity. Study 2: More premature responses occurred after premature responses in stimulant-dependent subjects. Conclusions: We show that methylphenidate has dissociable effects on waiting and reflection impulsivity. Chronic stimulant exposure impairs learning from prior premature responses, suggesting a failure to learn that premature responding is suboptimal. These findings provide a greater mechanistic understanding of waiting impulsivity. PMID:26136351

  12. Impulsivity and rapid decision-making for reward.

    PubMed

    Burnett Heyes, Stephanie; Adam, Robert J; Urner, Maren; van der Leer, Leslie; Bahrami, Bahador; Bays, Paul M; Husain, Masud

    2012-01-01

    Impulsivity is a feature of many brain disorders. Although often defined as the predisposition to act with an inadequate degree of deliberation, forethought, or control, it has proven difficult to measure. This may in part be due to the fact that it is a multifaceted construct, with impulsive decisions potentially arising as a result of a number of underlying mechanisms. Indeed, a "functional" degree of impulsivity may even promote effective behavior in healthy participants in a way that can be advantageous under certain circumstances. Although many tasks have been developed to study impulsivity, few examine decisions made rapidly, for time-sensitive rewards. In the current study we examine behavior in 59 adults on a manual "Traffic Light" task which requires participants to take risks under time pressure, if they are to maximize reward. We show that behavioral variables that index rapid anticipatory responding in this paradigm are correlated with one, specific self-report measure of impulsivity: "lack of premeditation" on the UPPS Impulsive Behavior Scale. Participants who scored more highly on this subscale performed better on the task. Moreover, anticipatory behavior reduced significantly with age (18-79 years), an effect that continued to be upheld after correction for potential age differences in the ability to judge the timing of responses. Based on these findings, we argue that the Traffic Light task provides a parametric method to study one aspect of impulsivity in health and disease: namely, rapid decision-making in pursuit of risky, time-sensitive rewards. PMID:22661960

  13. On the Feasibility of Quantifying Fibrous Cap Thickness With Acoustic Radiation Force Impulse (ARFI) Ultrasound.

    PubMed

    Czernuszewicz, Tomasz J; Gallippi, Caterina M

    2016-09-01

    Acute cerebrovascular accidents are associated with the rupture of vulnerable atherosclerotic plaques in the carotid arteries. Fibrous cap (FC) thickness has been shown to be an important predictor of plaque rupture but has been challenging to measure accurately with clinical noninvasive imaging modalities. The goals of this investigation were first, to evaluate the feasibility of using transcutaneous acoustic radiation force impulse (ARFI) ultrasound to quantify FC thickness and second, to optimize both imaging and motion-tracking parameters to support such measurements. FCs with varying thickness (0.1-1.0 mm) were simulated using a simple-layered geometry, and their mechanical response to an impulse of radiation force was solved using finite-element method (FEM) modeling. Ultrasound tracking of FEM displacements was performed in Field II utilizing three center frequencies (6, 9, and 12 MHz) and eight motion-tracking kernel lengths ( 0.5λ-4λ). Additionally, FC thickness in two carotid plaques imaged in vivo was measured with ARFI and compared to matched histology. The results of this study demonstrate that 1) tracking pulse frequencies around 12 MHz are necessary to resolve caps around 0.2 mm; 2) large motion-tracking kernel sizes introduce bias into thickness measurements and overestimate the true cap thickness; and 3) color saturation settings on ARFI peak displacement images can impact thickness measurement accuracy substantially. PMID:26955026

  14. Knee abduction angular impulses during prolonged running with wedged insoles.

    PubMed

    Lewinson, Ryan T; Worobets, Jay T; Stefanyshyn, Darren J

    2013-07-01

    Wedged insoles may produce immediate effects on knee abduction angular impulses during running; however, it is currently not known whether these knee abduction angular impulse magnitudes are maintained throughout a run when fatigue sets in. If changes occur, this could affect the clinical utility of wedged insoles in treating conditions such as patellofemoral pain. Thus, the purpose of this study was to determine whether knee abduction angular impulses are altered during a prolonged run with wedged insoles. It was hypothesized that knee abduction angular impulses would be reduced following a prolonged run with wedged insoles. Nine healthy runners participated. Runners were randomly assigned to either a 6-mm medial wedge condition or a 6-mm lateral wedge condition and then ran continuously overground for 30 min. Knee abduction angular impulses were quantified at 0 and 30 min using a gait analysis procedure. After 2 days, participants returned to perform the same test but with the other wedge type. Two-way repeated-measures analysis of variance was used to evaluate main effects of wedge condition and time and interactions between wedge condition and time (α = 0.05). Paired t-tests were used for post hoc analysis (α = 0.01). No interaction effects (p = 0.958) were found, and knee abduction angular impulses were not significantly different over time (p = 0.384). Lateral wedge conditions produced lesser knee abduction angular impulses than medial conditions at 0 min (difference of 2.79 N m s, p = 0.006) and at 30 min (difference of 2.76 N m s, p < 0.001). It is concluded that significant knee abduction angular impulse changes within wedge conditions do not occur during a 30-min run. Additionally, knee abduction angular impulse differences between wedge conditions are maintained during a 30-min run.

  15. Temperament and Impulsivity Predictors of Smoking Cessation Outcomes

    PubMed Central

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

    2014-01-01

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

  16. Impulsivity in disorders of food and drug misuse

    PubMed Central

    Mole, Tom B.; Irvine, Michael A.; Worbe, Yulia; Collins, Phoebe; Mitchell, Simon P.; Bolton, Sorcha; Harrison, Neil A.; Robbins, Trevor W.; Voon, Valerie

    2016-01-01

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

  17. Alcohol increases impulsivity and abuse liability in heavy drinking women.

    PubMed

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

    2012-12-01

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

  18. Greater Impulsivity is Associated with Decreased Brain Activation in Obese Women during a Delay Discounting Task

    PubMed Central

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

    2012-01-01

    Impulsivity and poor inhibitory control are associated with higher rates of delay discounting (DD) or a greater preference for smaller, more immediate rewards at the expense of larger, but delayed rewards. Of the many functional magnetic resonance imaging (fMRI) studies of DD, few have investigated the correlation between individual differences in DD rate and brain activation related to DD trial difficulty, with difficult DD trials expected to activate putative executive function brain areas involved in impulse control. In the current study, we correlated patterns of brain activation as measured by fMRI during difficult vs. easy trials of a DD task with DD rate (k) in obese women. Difficulty was defined by how much a reward choice deviated from an individual’s ‘indifference point’, or the point where the subjective preference for an immediate and a delayed reward was approximately equivalent. We found that greater delay discounting was correlated with less modulation of activation in putative executive function brain areas, such as the middle and superior frontal gyri and inferior parietal lobule, in response to difficult compared to easy DD trials. These results support the suggestion that increased impulsivity is associated with deficient functioning of executive function areas of the brain. PMID:22948956

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

    PubMed

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

    2014-01-01

    A well-characterized potential marker for addiction is impulsive choice, stably measured by delay discounting (DD) paradigms. While genetic influences partly account for inter-individual variance in impulsivity, environmental factors such as parenting practices may have an important role. The present study investigates how inconsistent fulfillment of delayed reward promises impacts on DD. A combined correlational and experimental functional magnetic resonance imaging (fMRI) design was performed in a sample of 48 healthy adolescents (13-15 years). More specifically, neural activation during a DD task was investigated at two assessment points (T0 and T1). Adolescents' self-reports of parenting and substance use were assessed at T0. Between assessment points, we experimentally varied the reliability of delayed reward promises, measuring the impact of this intervention on DD and neural value processing at T1. In the correlational part, same-sex parent reward inconsistency was associated with steeper DD and an attenuated subjective value (SV) representation in the nucleus accumbens (NAcc) and ventromedial prefrontal cortex (vmPFC). Steeper DD was in turn associated with alcohol use during the past year. In the experimental part, the reward inconsistency manipulation resulted in an attenuation of the NAcc SV representation, similar to the parental inconsistency effect. Together, our correlational and experimental findings raise new light on how parents may influence their children's degree of impulsivity, making parenting a potential target in addiction prevention. PMID:24736798

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

    PubMed Central

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

    2014-01-01

    A well-characterized potential marker for addiction is impulsive choice, stably measured by delay discounting (DD) paradigms. While genetic influences partly account for inter-individual variance in impulsivity, environmental factors such as parenting practices may have an important role. The present study investigates how inconsistent fulfillment of delayed reward promises impacts on DD. A combined correlational and experimental functional magnetic resonance imaging (fMRI) design was performed in a sample of 48 healthy adolescents (13–15 years). More specifically, neural activation during a DD task was investigated at two assessment points (T0 and T1). Adolescents' self-reports of parenting and substance use were assessed at T0. Between assessment points, we experimentally varied the reliability of delayed reward promises, measuring the impact of this intervention on DD and neural value processing at T1. In the correlational part, same-sex parent reward inconsistency was associated with steeper DD and an attenuated subjective value (SV) representation in the nucleus accumbens (NAcc) and ventromedial prefrontal cortex (vmPFC). Steeper DD was in turn associated with alcohol use during the past year. In the experimental part, the reward inconsistency manipulation resulted in an attenuation of the NAcc SV representation, similar to the parental inconsistency effect. Together, our correlational and experimental findings raise new light on how parents may influence their children's degree of impulsivity, making parenting a potential target in addiction prevention. PMID:24736798