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Sample records for temporal impulse response

  1. Spatio-temporal dynamics of impulse responses to figure motion in optic flow neurons.

    Directory of Open Access Journals (Sweden)

    Yu-Jen Lee

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

  2. A Temporal White Noise Analysis for Extracting the Impulse Response Function of the Human Electroretinogram.

    Science.gov (United States)

    Zele, Andrew J; Feigl, Beatrix; Kambhampati, Pradeep K; Aher, Avinash; McKeefry, Declan; Parry, Neil; Maguire, John; Murray, Ian; Kremers, Jan

    2017-11-01

    We introduce a method for determining the impulse response function (IRF) of the ERG derived from responses to temporal white noise (TWN) stimuli. This white noise ERG (wnERG) was recorded in participants with normal trichromatic vision to full-field (Ganzfeld) and 39.3° diameter focal stimuli at mesopic and photopic mean luminances and at different TWN contrasts. The IRF was obtained by cross-correlating the TWN stimulus with the wnERG. We show that wnERG recordings are highly repeatable, with good signal-to-noise ratio, and do not lead to blink artifacts. The wnERG resembles a flash ERG waveform with an initial negativity (N1) followed by a positivity (P1), with amplitudes that are linearly related to stimulus contrast. These N1 and N1-P1 components showed commonalties in implicit times with the a- and b-waves of flash ERGs. There was a clear transition from rod- to cone-driven wnERGs at ∼1 photopic cd.m -2 . We infer that oscillatory potentials found with the flash ERG, but not the wnERG, may reflect retinal nonlinearities due to the compression of energy into a short time period during a stimulus flash. The wnERG provides a new approach to study the physiology of the retina using a stimulation method with adaptation and contrast conditions similar to natural scenes to allow for independent variation of stimulus strength and mean luminance, which is not possible with the conventional flash ERG. The white noise ERG methodology will be of benefit for clinical studies and animal models in the evaluation of hypotheses related to cellular redundancy to understand the effects of disease on specific visual pathways.

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

    Science.gov (United States)

    Bhaumik, Swagata; Sengupta, Tapan K.

    2017-12-01

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

  4. ESTIMATION OF IMPULSE RESPONSE FUNCTION BY ...

    African Journals Online (AJOL)

    The method proves stable in both numerical and statistical sense. There was no instability observed up to 80 input variables. KEY WORDS: Iterative multiple regression, impulse response function, error square contribution, time series analysis, transfer function model. Global Jnl of Mathematical Sciences Vol. 3(1) 2004: 47- ...

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Jodi M Gilman

    Full Text Available 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.

  7. A new Calculation Procedure for Spatial Impulse Responses in Ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    1999-01-01

    A new procedure for the calculation of spatial impulse responses for linear sound fields is introduced. This calculation procedure uses the well known technique of calculating the spatial impulse response from the intersection of a circle emanating from the projected spherical wave...

  8. A new approach to calculating spatial impulse responses

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    1997-01-01

    Using linear acoustics the emitted and scattered ultrasound field can be found by using spatial impulse responses as developed by Tupholme (1969) and Stepanishen (1971). The impulse response is calculated by the Rayleigh integral by summing the spherical waves emitted from all of the aperture...... of the emitting aperture. Summing the angles of the arcs within the aperture readily yields the spatial impulse response for a point in space. The approach makes is possible to make very general calculation routines for arbitrary, flat apertures in which the outline of the aperture is either analytically...... be used for finding analytic solutions to the spatial impulse response for new geometries of, for example, ellipsoidal shape. The approach also makes it easy to incorporate any apodization function and the effect from different transducers baffle mountings. Examples of spatial impulse responses...

  9. Numerical analysis on acoustic impulse response for watermelon

    International Nuclear Information System (INIS)

    Kim, Yong Sul; Yang, Dong Hoon; Choi, Young Jae; Bae, Tas Joo; So, Chul Ho; Lee, Yun Ho

    2002-01-01

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

  10. Numerical analysis on acoustic impulse response for watermelon

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-11-15

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

  11. Spatial impulse response of a rectangular double curved transducer

    DEFF Research Database (Denmark)

    Bæk, David; Jensen, Jørgen Arendt; Willatzen, Morten

    2012-01-01

    Calculation of the pressure field from transducers having both a convex and a concave surface geometry is a complicated assignment that often is accomplished by subdividing the transducer surface into smaller flat elements of which the spatial impulse response is known. This method is often seen...... applied to curved transducers because an analytical solution is un-known. In this work a semi-analytical algorithm for the exact solution to a first order in diffraction effect of the spatial impulse response of rectangular shaped double curved transducers is presented. The algorithm and an approximation...... approximations ranging from 0.03 % to 0.8 % relative to a numerical solution for the spatial impulse response. It is shown that the presented algorithm gives consistent results with Field II for a linear flat, a linear focused, and a convex non-focused element. Best solution was found to be 0.01 % with a three...

  12. Impulse response method for characterization of echogenic liposomes

    NARCIS (Netherlands)

    Raymond, J.L.; Luan, Y.; van Rooij, T.; Kooiman, K.; Huang, S.L.; McPherson, D.D.; Versluis, Michel; de Jong, N.; Holland, C.K.

    2015-01-01

    An optical characterization method is presented based on the use of the impulse response to characterize the damping imparted by the shell of an air-filled ultrasound contrast agent (UCA). The interfacial shell viscosity was estimated based on the unforced decaying response of individual echogenic

  13. Subtypes of trait impulsivity differentially correlate with neural responses to food choices

    NARCIS (Netherlands)

    Laan, van der Laura N.; Barendse, Marjolein E.A.; Viergever, M.A.; Smeets, P.A.M.

    2016-01-01

    Impulsivity is a personality trait that is linked to unhealthy eating and overweight. A few studies assessed how impulsivity relates to neural responses to anticipating and tasting food, but it is unknown how impulsivity relates to neural responses during food choice. Although impulsivity is a

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

    Science.gov (United States)

    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.

  15. Model Predictive Control based on Finite Impulse Response Models

    DEFF Research Database (Denmark)

    Prasath, Guru; Jørgensen, John Bagterp

    2008-01-01

    We develop a regularized l2 finite impulse response (FIR) predictive controller with input and input-rate constraints. Feedback is based on a simple constant output disturbance filter. The performance of the predictive controller in the face of plant-model mismatch is investigated by simulations ...

  16. Understanding Computation of Impulse Response in Microwave Software Tools

    Science.gov (United States)

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

    2010-01-01

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

  17. Multichannel Room Impulse Response Generation With Coherence Control

    NARCIS (Netherlands)

    Kuster, M.

    2009-01-01

    A method is proposed by which an arbitrary number of room impulse responses (RIRs) is generated from one input RIR. The method works by convolving the input RIR with a multitude of filters, one for each desired output RIR. The filters are designed in such a way that the coherence between all

  18. Impulse and Frequency Response of a Moving Coil Galvanometer.

    Science.gov (United States)

    McNeill, D. J.

    1985-01-01

    Describes an undergraduate laboratory experiment in which a moving coil galvanometer is studied and the electromotive force generated by the swinging coil provides the impulse response information in a form suitable for digitizing and inputing to a microcomputer. Background information and analysis of typical data are included. (JN)

  19. Astrocytes promote myelination in response to electrical impulses.

    Science.gov (United States)

    Ishibashi, Tomoko; Dakin, Kelly A; Stevens, Beth; Lee, Philip R; Kozlov, Serguei V; Stewart, Colin L; Fields, R Douglas

    2006-03-16

    Myelin, the insulating layers of membrane wrapped around axons by oligodendrocytes, is essential for normal impulse conduction. It forms during late stages of fetal development but continues into early adult life. Myelination correlates with cognitive development and can be regulated by impulse activity through unknown molecular mechanisms. Astrocytes do not form myelin, but these nonneuronal cells can promote myelination in ways that are not understood. Here, we identify a link between myelination, astrocytes, and electrical impulse activity in axons that is mediated by the cytokine leukemia inhibitory factor (LIF). These findings show that LIF is released by astrocytes in response to ATP liberated from axons firing action potentials, and LIF promotes myelination by mature oligodendrocytes. This activity-dependent mechanism promoting myelination could regulate myelination according to functional activity or environmental experience and may offer new approaches to treating demyelinating diseases.

  20. Retrieving impulse response function amplitudes from the ambient seismic field

    Science.gov (United States)

    Viens, Loïc; Denolle, Marine; Miyake, Hiroe; Sakai, Shin'ichi; Nakagawa, Shigeki

    2017-07-01

    Seismic interferometry is now widely used to retrieve the impulse response function of the Earth between two distant seismometers. The phase information has been the focus of most passive imaging studies, as conventional seismic tomography uses traveltime measurements. The amplitude information, however, is harder to interpret because it strongly depends on the distribution of ambient seismic field sources and on the multitude of processing methods. Our study focuses on the latter by comparing the amplitudes of the impulse response functions calculated between seismic stations in the Kanto sedimentary basin, Japan, using several processing techniques. This region provides a unique natural laboratory to test the reliability of the amplitudes with complex wave propagation through the basin, and dense observations from the Metropolitan Seismic Observation network. We compute the impulse response functions using the cross correlation, coherency and deconvolution techniques of the raw ambient seismic field and the cross correlation of 1-bit normalized data. To validate the amplitudes of the impulse response functions, we use a shallow Mw 5.8 earthquake that occurred on the eastern edge of Kanto Basin and close to a station that is used as the virtual source. Both S and surface waves are retrieved in the causal part of the impulse response functions computed with all the different techniques. However, the amplitudes obtained from the deconvolution method agree better with those of the earthquake. Despite the expected wave attenuation due to the soft sediments of the Kanto Basin, seismic amplification caused by the basin geometry dominates the amplitudes of S and surface waves and is captured by the ambient seismic field. To test whether or not the anticausal part of the impulse response functions from deconvolution also contains reliable amplitude information, we use another virtual source located on the western edge of the basin. We show that the surface wave amplitudes

  1. Calculation of reactivity using a finite impulse response filter

    Energy Technology Data Exchange (ETDEWEB)

    Suescun Diaz, Daniel [COPPE/UFRJ, Programa de Engenharia Nuclear, Caixa Postal 68509, CEP 21941-914, RJ (Brazil); Senra Martinez, Aquilino [COPPE/UFRJ, Programa de Engenharia Nuclear, Caixa Postal 68509, CEP 21941-914, RJ (Brazil)], E-mail: aquilino@lmp.ufrj.br; Carvalho Da Silva, Fernando [COPPE/UFRJ, Programa de Engenharia Nuclear, Caixa Postal 68509, CEP 21941-914, RJ (Brazil)

    2008-03-15

    A new formulation is presented in this paper to solve the inverse kinetics equation. This method is based on the Laplace transform of the point kinetics equations, resulting in an expression equivalent to the inverse kinetics equation as a function of the power history. Reactivity can be written in terms of the summation of convolution with response to impulse, characteristic of a linear system. For its digital form the Z-transform is used, which is the discrete version of the Laplace transform. This new method of reactivity calculation has very special features, amongst which it can be pointed out that the linear part is characterized by a filter named finite impulse response (FIR). The FIR filter will always be, stable and non-varying in time, and, apart from this, it can be implemented in the non-recursive form. This type of implementation does not require feedback, allowing the calculation of reactivity in a continuous way.

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

    OpenAIRE

    Herbort, Maike C.; Soch, Joram; W?stenberg, Torsten; Krauel, Kerstin; Pujara, Maia; Koenigs, Michael; Gallinat, J?rgen; Walter, Henrik; Roepke, Stefan; Schott, Bj?rn H.

    2016-01-01

    Patients with borderline personality disorder (BPD) frequently exhibit impulsive behavior, and self-reported impulsivity is typically higher in BPD patients when compared to healthy controls. Previous functional neuroimaging studies have suggested a link between impulsivity, the ventral striatal response to reward anticipation, and prediction errors. Here we investigated the striatal neural response to monetary gain and loss anticipation and their relationship with impulsivity in 21 female BP...

  3. Identification of pulse echo impulse responses for multi source transmission

    DEFF Research Database (Denmark)

    Gran, Fredrik; Jensen, Jørgen Arendt

    2004-01-01

    is a mixture of the information corresponding to several transmitters. There is, thus, no direct way of determining which information corresponds to which transmitter, preventing proper focusing. In this paper we decode the received signal by estimating the pulse echo impulse responses between every....... The method is evaluated using the simulation tool Field II. Three point spread functions are simulated where axial movement of 1 m/s is present. The axial resolution for the moving scatterer is 0.249 mm (-3dB) and 0.291 mm (-6dB), which is compared to a standard STA transmission scheme with sequential...

  4. Direction Finding Using an Antenna with Direction Dependent Impulse Response

    Science.gov (United States)

    Foltz, Heinrich; Kegege, Obadiah

    2016-01-01

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

  5. Design and application of finite impulse response digital filters.

    Science.gov (United States)

    Miller, T R; Sampathkumaran, K S

    1982-01-01

    The finite impulse response (FIR) digital filter is a spatial domain filter with a frequency domain representation. The theory of the FIR filter is presented and techniques are described for designing FIR filters with known frequency response characteristics. Rational design principles are emphasized based on characterization of the imaging system using the modulation transfer function and physical properties of the imaged objects. Bandpass, Wiener, and low-pass filters were designed and applied to 201Tl myocardial images. The bandpass filter eliminates low-frequency image components that represent background activity and high-frequency components due to noise. The Wiener, or minimum mean square error filter 'sharpens' the image while also reducing noise. The Wiener filter illustrates the power of the FIR technique to design filters with any desired frequency response. The low-pass filter, while of relative limited use, is presented to compare it with a popular elementary 'smoothing' filter.

  6. Synthesis of Room Impulse Responses for Variable Source Characteristics

    Directory of Open Access Journals (Sweden)

    M. Kunkemoeller

    2011-01-01

    Full Text Available Every acoustic source, e.g. a speaker, a musical instrument or a loudspeaker, generally has a frequency dependent characteristic radiation pattern, which is preeminent at higher frequencies. Room acoustic measurements nowadays only account for omnidirectional source characteristics. This motivates a measurement method that is capable of obtaining room impulse responses for these specific radiation patterns by using a superposition approach of several measurements with technically well-defined sound sources. We propose a method based on measurements with a 12-channel independentlydriven dodecahedron loudspeaker array rotated by an automatically controlled turntable.Radiation patterns can be efficiently described with the use of spherical harmonics representation. We propose a method that uses this representation for the spherical loudspeaker array used for the measurements and the target radiation pattern to be used for the synthesis.We show validating results for a deterministic test sound source inside in a small lecture hall.

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

    Science.gov (United States)

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

    2010-01-01

    Dopaminergic medication-related impulse control disorders (ICDs) such as pathological gambling and compulsive shopping have been reported in Parkinson's disease (PD). 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). Fourteen PDI patients, 14 PD controls without ICDs, and 16 medication-free matched normal controls were tested on the Experiential Discounting Task (EDT), a feedback-based intertemporal choice task, spatial working memory, and attentional set shifting. The EDT was used to assess choice impulsivity (hyperbolic K value), reaction time (RT), and decision conflict RT (the RT difference between high conflict and low conflict choices). PDI patients and PD controls were tested on and off DA. 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). Greater impulsive choice, faster RT, faster decision conflict RT, and executive dysfunction may contribute to ICDs in PD.

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

    Science.gov (United States)

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

    2014-01-01

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

  9. Dynamic Characterization and Impulse Response Modeling of Amplitude and Phase Response of Silicon Nanowires

    DEFF Research Database (Denmark)

    Cleary, Ciaran S.; Ji, Hua; Dailey, James M.

    2013-01-01

    Amplitude and phase dynamics of silicon nanowires were measured using time-resolved spectroscopy. Time shifts of the maximum phase change and minimum amplitude as a function of pump power due to saturation of the free-carrier density were observed. A phenomenological impulse response model used...

  10. Adults with a family history of alcohol related problems are more impulsive on measures of response initiation and response inhibition.

    Science.gov (United States)

    Acheson, Ashley; Richard, Dawn M; Mathias, Charles W; Dougherty, Donald M

    2011-09-01

    Previous studies have found individuals with family histories of alcohol use disorders are more impulsive on some but not all laboratory behavioral measures, suggesting deficits on specific forms of impulse control. However, drawing conclusions is tenuous because these different measures have not been administered together in the same group of participants. In the present study, we compared healthy 21-35 year old adults with family histories of alcohol related problems (FHAP+) or without such histories (FHAP-) on behavioral measures of response inhibition, response initiation, and consequence sensitivity impulsivity. FHAP+ (n=36) and FHAP- (n=36) participants were compared on performance on the Immediate Memory Task (IMT, response initiation), GoStop Impulsivity Paradigm (GoStop, response inhibition), Two Choice Impulsivity Paradigm (TCIP, consequence sensitivity) and Single Key Impulsivity Paradigm (SKIP, consequence sensitivity). FHAP+ individuals were more impulsive on the IMT and GoStop but not on the TCIP or SKIP. These results suggest that response initiation and response inhibition impulsivity are increased in individuals with family histories of alcohol related problems despite not having alcohol or drug use disorders themselves. In contrast, increased consequence sensitivity impulsivity may be associated with additional risk factors such as more severe family histories of alcohol use disorders, or it may be increased as a consequence of heavy drug or alcohol use. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  11. CO2 impulse response curves for GWP calculations

    International Nuclear Information System (INIS)

    Jain, A.K.; Wuebbles, D.J.

    1993-01-01

    The primary purpose of Global Warming Potential (GWP) is to compare the effectiveness of emission strategies for various greenhouse gases to those for CO 2 , GWPs are quite sensitive to the amount of CO 2 . Unlike all other gases emitted in the atmosphere, CO 2 does not have a chemical or photochemical sink within the atmosphere. Removal of CO 2 is therefore dependent on exchanges with other carbon reservoirs, namely, ocean and terrestrial biosphere. The climatic-induced changes in ocean circulation or marine biological productivity could significantly alter the atmospheric CO 2 lifetime. Moreover, continuing forest destruction, nutrient limitations or temperature induced increases of respiration could also dramatically change the lifetime of CO 2 in the atmosphere. Determination of the current CO 2 sinks, and how these sinks are likely to change with increasing CO 2 emissions, is crucial to the calculations of GWPs. It is interesting to note that the impulse response function is sensitive to the initial state of the ocean-atmosphere system into which CO 2 is emitted. This is due to the fact that in our model the CO 2 flux from the atmosphere to the mixed layer is a nonlinear function of ocean surface total carbon

  12. Structural response of reinforced concrete slabs to impulsive loads

    International Nuclear Information System (INIS)

    Florence, A.L.

    1977-01-01

    The structure treated here is a clamped circular slab of reinforced concrete. The loading is a rectangular pulse uniformly distributed over a central area. The practical value of this problem is that it probably represents a most severe loading case for bending response among more realistic cases, because it replaces the local loaded area with a circular area at the slab center, and because it replaces the pulse with a rectangular pulse of the same peak pressure and impulse. In the theoretical treatment the pulse is assumed to produce plastic deformations large enough to neglect elastic deformation but small enough to neglect membrane action. Yielding of the reinforced concrete slab is assumed to be governed by the Johansen criterion and the associated flow rule. For simplicity, the analysis is restricted to isotropic slabs with top and bottom steel reinforcement arranged to provide the same yield moment magnitude for positive and negative curvature changes. A consequence of the assumed rigid-perfectly plastic behavior is that the deformation modes may be considered as simple mechanism governed by a yield circle. Moreover, the yield circle is stationary while the constant pressure is being applied and expands to the support once the pressure is removed. After the yield circle has arrived at the support, the remaining deformation occurs in the static collapse mode. The principal results are explicit simple formulas for permanent central deflection in terms of pressure, duration, loaded area radius, and plate properties (radius, density, yield moment)

  13. Increased multiaxial lumbar motion responses during multiple-impulse mechanical force manually assisted spinal manipulation

    Directory of Open Access Journals (Sweden)

    Gunzburg Robert

    2006-04-01

    Full Text Available Abstract Background Spinal manipulation has been found to create demonstrable segmental and intersegmental spinal motions thought to be biomechanically related to its mechanisms. In the case of impulsive-type instrument device comparisons, significant differences in the force-time characteristics and concomitant motion responses of spinal manipulative instruments have been reported, but studies investigating the response to multiple thrusts (multiple impulse trains have not been conducted. The purpose of this study was to determine multi-axial segmental and intersegmental motion responses of ovine lumbar vertebrae to single impulse and multiple impulse spinal manipulative thrusts (SMTs. Methods Fifteen adolescent Merino sheep were examined. Tri-axial accelerometers were attached to intraosseous pins rigidly fixed to the L1 and L2 lumbar spinous processes under fluoroscopic guidance while the animals were anesthetized. A hand-held electromechanical chiropractic adjusting instrument (Impulse was used to apply single and repeated force impulses (13 total over a 2.5 second time interval at three different force settings (low, medium, and high along the posteroanterior axis of the T12 spinous process. Axial (AX, posteroanterior (PA, and medial-lateral (ML acceleration responses in adjacent segments (L1, L2 were recorded at a rate of 5000 samples per second. Peak-peak segmental accelerations (L1, L2 and intersegmental acceleration transfer (L1–L2 for each axis and each force setting were computed from the acceleration-time recordings. The initial acceleration response for a single thrust and the maximum acceleration response observed during the 12 multiple impulse trains were compared using a paired observations t-test (POTT, alpha = .05. Results Segmental and intersegmental acceleration responses mirrored the peak force magnitude produced by the Impulse Adjusting Instrument. Accelerations were greatest for AX and PA measurement axes. Compared to

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

    Science.gov (United States)

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

    2015-08-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Maike C. Herbort

    2016-01-01

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

  17. Limitations caused by distortion in room impulse response measurements by swept sine technique

    DEFF Research Database (Denmark)

    Stojic, Branko; Ciric, Dejan; Markovic, Milos

    2011-01-01

    The significance of a room impulse response implies the requirement that its measurement should have a high level of accuracy in certain applications. One of the common problems in a measurement process is nonlinearity leading to the distortion of a room impulse response. Limitations caused...... by the distortion in room impulse response measurements by swept sine technique are analyzed here by the simulations and measurements. For the investigation, both linear and exponential swept sines are used as an excitation signal. In the simulations, this signal is modified by the nonlinearity model in the time...

  18. Kurtosis of room impulse responses as a diffuseness measure for reverberation chambers

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2016-01-01

    This study presents a kurtosis analysis of room impulse responses as a potential room diffuseness measure. The early part of an impulse response contains a direct sound and strong reflections. As these reflections are sparse and strong, the sound field is unlikely to be diffuse. Such deterministic...... significantly in a small room. A full scale reverberation chamber is tested with different diffuser settings, which shows that the kurtosis calculated from broadband impulse responses from 125 Hz to 4 kHz has a good correlation with the Sabine absorption coefficient according to ISO 354 (International...

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

    Science.gov (United States)

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

    2015-02-01

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

  20. Reliability of estimating the room volume from a single room impulse response

    OpenAIRE

    Kuster, M.

    2008-01-01

    The methods investigated for the room volume estimation are based on geometrical acoustics, eigenmode, and diffuse field models and no data other than the room impulse response are available. The measurements include several receiver positions in a total of 12 rooms of vastly different sizes and acoustic characteristics. The limitations in identifying the pivotal specular reflections of the geometrical acoustics model in measured room impulse responses are examined both theoretically and expe...

  1. Robust finite impulse response beamforming applied to medical ultrasound.

    Science.gov (United States)

    Guenther, Drake A; Walker, William F

    2009-06-01

    We previously described a beamformer architecture that replaces the single apodization weights on each receive channel with channel-unique finite impulse response (FIR) filters. The filter weights are designed to optimize the contrast resolution performance of the imaging system. Although the FIR beamformer offers significant gains in contrast resolution, the beamformer suffers from low sensitivity, and its performance rapidly degrades in the presence of noise. In this paper, a new method is presented to improve the robustness of the FIR beamformer to electronic noise as well as variation or uncertainty in the array response. A method is also described that controls the sidelobe levels of the FIR beamformer's spatial response by applying an arbitrary weighting function in the filter design algorithm. The robust FIR beamformer is analyzed using a generalized cystic resolution metric that quantifies a beamformer's clinical imaging performance as a function of cyst size and channel input SNR. Fundamental performance limits are compared between 2 robust FIR beamformers - the dynamic focus FIR (DF-FIR) beamformer and the group focus FIR (GF-FIR) beamformer - the conventional delay-and-sum (DAS) beamformer, and the spatial-matched filter (SMF) beamformer. Results from this study show that the new DF- and GF-FIR beamformers are more robust to electronic noise compared with the optimal contrast resolution FIR beamformer. Furthermore, the added robustness comes with only a slight loss in cystic resolution. Results from the generalized cystic resolution metric show that a 9-tap robust FIR beamformer outperforms the SMF and DAS beamformer until receive channel input SNR drops below -5 dB, whereas the 9-tap optimal contrast resolution beamformer's performance deteriorates around 50 dB SNR. The effects of moderate phase aberrations, characterized by an a priori root-mean-square strength of 28 ns and an a priori full-width at half-maximum correlation length of 3.6 mm, are

  2. Reflection impulsivity and response inhibition in first-episode psychosis: relationship to cannabis use.

    Science.gov (United States)

    Huddy, V C; Clark, L; Harrison, I; Ron, M A; Moutoussis, M; Barnes, T R E; Joyce, E M

    2013-10-01

    People with psychosis demonstrate impaired response inhibition on the Stop Signal Task (SST). It is less clear if this impairment extends to reflection impulsivity, a form of impulsivity that has been linked to substance use in non-psychotic samples. We compared 49 patients with first-episode psychosis (FEP) and 30 healthy control participants on two forms of impulsivity measured using the Information Sampling Test (IST) and the SST, along with clinical and IQ assessments. We also compared those patients who used cannabis with those who had either given up or never used. Patients with FEP had significantly greater impairment in response inhibition but not in reflection impulsivity compared with healthy controls. By contrast, patients who reported current cannabis use demonstrated greater reflection impulsivity than those that had either given up or never used, whereas there were no differences in response inhibition. These data suggest that abnormal reflection impulsivity is associated with substance use in psychosis but not psychosis itself ; the opposite relationship may hold for response inhibition.

  3. Impulsivity and Stress Response in Pathological Gamblers During the Trier Social Stress Test.

    Science.gov (United States)

    Maniaci, G; Goudriaan, A E; Cannizzaro, C; van Holst, R J

    2018-03-01

    Gambling has been associated with increased sympathetic nervous system output and stimulation of the hypothalamic-pituitary-adrenal axis. However it is unclear how these systems are affected in pathological gambling. This study aimed to investigate the effect of the Trier Social Stress Test (TSST) on cortisol and on cardiac interbeat intervals in relation to impulsivity, in a sample of male pathological gamblers compared to healthy controls. In addition, we investigated the correlation between the TSST, duration of the disorder and impulsivity. A total of 35 pathological gamblers and 30 healthy controls, ranging from 19 to 58 years old and all male, participated in this study. Stress response was measured during and after the TSST by salivary cortisol and cardiac interbeat intervals; impulsivity was assessed with the Barratt Impulsiveness Scale (BIS-11). Exposure to the TSST produced a significant increase in salivary cortisol and interbeat intervals in both groups, without differences between groups. We found a negative correlation between baseline cortisol and duration of pathological gambling indicating that the longer the duration of the disorder the lower the baseline cortisol levels. Additionally, we found a main effect of impulsivity across groups on interbeat interval during the TSST, indicating an association between impulsivity and the intensity of the neurovegetative stress response during the TSST. Involvement of the hypothalamic-pituitary-adrenal axis in pathological gambling was confirmed together with evidence of a correlation between length of the disorder and diminished baseline cortisol levels. Impulsivity emerged as a personality trait expressed by pathological gamblers; however the neurovegetative response to the TSST, although associated with impulsivity, appeared to be independent of the presence of pathological gambling.

  4. Impulse response identification with deterministic inputs using non-parametric methods

    International Nuclear Information System (INIS)

    Bhargava, U.K.; Kashyap, R.L.; Goodman, D.M.

    1985-01-01

    This paper addresses the problem of impulse response identification using non-parametric methods. Although the techniques developed herein apply to the truncated, untruncated, and the circulant models, we focus on the truncated model which is useful in certain applications. Two methods of impulse response identification will be presented. The first is based on the minimization of the C/sub L/ Statistic, which is an estimate of the mean-square prediction error; the second is a Bayesian approach. For both of these methods, we consider the effects of using both the identity matrix and the Laplacian matrix as weights on the energy in the impulse response. In addition, we present a method for estimating the effective length of the impulse response. Estimating the length is particularly important in the truncated case. Finally, we develop a method for estimating the noise variance at the output. Often, prior information on the noise variance is not available, and a good estimate is crucial to the success of estimating the impulse response with a nonparametric technique

  5. Impulse response measurements as dependent on crack depth. Delamination

    International Nuclear Information System (INIS)

    Ulriksen, Peter

    2011-02-01

    The purpose of the project is to investigate the impulse-response method's ability to detect delamination at different depths. This method is of particular interest, since some of it's realizations strongly resembles established methods like 'bomknackning' . Since the personnel that will be responsible for future measurements with new technology, should feel confidence in new methods, it is an advantage if the new methods connect to older, accepted methods. The project consists of three parts and a fourth is planned. The first part of the investigation is made with a vibrator connected to an impedance head which in turn is connected to the surface of the concrete test specimen with internal delaminations at different depths. The vibrator is controlled by a dynamic signal analyze, which also measures the force- and acceleration signals from the impedance head and convert them to impedance. Since the impedance head must be glued to the surface of the concrete this method is only of laboratory interest. This method gives a complete description of the behavior of the concrete for the frequencies investigated. Thus in following investigations the frequencies of interest are known. From the experiment it follows that delamination down to a depth of 80-100 mm can be detected through a clear and solitary resonance peak. This resonance frequency is a function of concrete slab thickness and extension, so if the extension can be measured it may be possible to calculate depth. The second part of the investigation is about using an instrumented hammer to hit the different delamination specimens. The hammer is equipped with a force transducer giving an opportunity to measure the force exerted by the strike against the concrete surface. When a hammer is struck against a concrete surface a spectrum of vibrations is created, dependent on the weight of the hammer and the elasticity of the concrete. A light hammer generates higher frequencies than a heavy one. Three different hammer

  6. An objective measure for the sensitivity of the room impulse response

    DEFF Research Database (Denmark)

    Prislan, Rok; Brunskog, Jonas; Jacobsen, Finn

    2013-01-01

    This study is relevant for a number of important acoustic measurements in reverberation rooms such as measurement of sound transmission and measurement of sound power levels of noise sources. From a pair of impulse responses measured in a room differing only in the position of the sound source......, it might be possible to quantify the sensitivity of the room due to changes in initial conditions. Such changes are linked to mixing. The proposed measure is the maximum of the absolute value of the cross-correlation between the time windowed sections of the two impulse responses. By integrating...... this quantity normalized by the energy of the impulse response of the room, a single number rating is obtained. The proposed measure is examined experimentally and the results are discussed. The results indicate that the number of absorbers and diffusers in the room influences the proposed measures...

  7. Impulse response of an S-cone pathway in the aging visual system

    Science.gov (United States)

    Shinomori, Keizo; Werner, John S.

    2006-07-01

    Age-related changes in the temporal properties of an S-cone pathway were characterized by the psychophysical impulse-response function (IRF). Participants included 49 color-normal observers ranging in age from 16.8 to 86.3 years. A double-pulse method was used to measure the IRF with S-cone modulation at constant luminance. Stimuli were presented as a Gaussian patch (±1SD=2.3°) in one of four quadrants around a central fixation cross on a CRT screen. The test stimulus was modulated from the equal-energy white of the background toward the short-wave spectrum locus. Each of the two pulses (6.67 ms) was separated by an interstimulus interval (ISI) from 20 to 720 ms. Chromatic detection thresholds were determined by a four-alternative forced-choice method with staircases for each ISI in one session. IRFs were calculated from the threshold data using a model with four parameters of an exponentially damped sine wave. S-cone IRFs have only an excitatory phase and a much longer time course compared with IRFs for luminance modulation measured with the same apparatus. The results demonstrated significant age-related losses in IRF amplitude, but the latency (time to peak) of the IRF was stable with age.

  8. Modeling transducer impulse responses for predicting calibrated pressure pulses with the ultrasound simulation program Field II

    DEFF Research Database (Denmark)

    Bæk, David; Jensen, Jørgen Arendt; Willatzen, Morten

    2010-01-01

    FIELD II is a simulation software capable of predicting the field pressure in front of transducers having any complicated geometry. A calibrated prediction with this program is, however, dependent on an exact voltage-to-surface acceleration impulse response of the transducer. Such impulse response...... is not calculated by FIELD II. This work investigates the usability of combining a one-dimensional multilayer transducer modeling principle with the FIELD II software. Multilayer here refers to a transducer composed of several material layers. Measurements of pressure and current from Pz27 piezoceramic disks...... transducer model and the FIELD II software in combination give good agreement with measurements....

  9. APPLICATION OF STIMULUS & RESPONSE MODEL TO IMPULSE BUYING BEHAVIOR OF ALGERIAN CONSUMERS

    Directory of Open Access Journals (Sweden)

    Amel Graa

    2012-02-01

    Full Text Available This paper investigates the influence of situational factors on the impulse buying behavior usinga Mehrabian and Russell's (1974 framework (Stimulus & response model. The results suggest thata consumer's emotions can be a mediating factor in the impulse purchase process. In this study, weidentify and explore how situational factors and emotional states may influence various dimensionsof impulse purchase behavior of Algerian shoppers. By tapping the responses of 687 consumers inthe area of Algeria’ west, we obtain that there is a positive relationship between independent anddependent variables.According to the results, pleasure was associated with design, whereas arousal was associatedwith perception of crowding, but dominance was linked to time spent in the store. Retailers can takethese findings to maintain trained their employees and provide adequate signs and best environmentwhenever some relocation of products took place.

  10. An Impulsive Three-Species Model with Square Root Functional Response and Mutual Interference of Predator

    Directory of Open Access Journals (Sweden)

    Zhen Wang

    2016-01-01

    Full Text Available An impulsive two-prey and one-predator model with square root functional responses, mutual interference, and integrated pest management is constructed. By using techniques of impulsive perturbations, comparison theorem, and Floquet theory, the existence and global asymptotic stability of prey-eradication periodic solution are investigated. We use some methods and sufficient conditions to prove the permanence of the system which involve multiple Lyapunov functions and differential comparison theorem. Numerical simulations are given to portray the complex behaviors of this system. Finally, we analyze the biological meanings of these results and give some suggestions for feasible control strategies.

  11. Impulsive response of nonuniform density liquid in a laterally excited tank

    International Nuclear Information System (INIS)

    Tang, Y.; Chang, Y.W.

    1994-04-01

    A study on the impulsive component of the dynamic response of a liquid of nonuniform density in a tank undergoing lateral base excitations is presented. The system considered is a circular cylindrical tank containing an incompressible and inviscid liquid whose density increases with the liquid depth. The density distribution along the depth can be of any arbitrary continuous or discontinuous function. In the analysis, the liquid field is divided into n layers. The thickness of the liquid layers can be different, but the density of each liquid layer is considered to be uniform and is equal to the value of the original liquid density at the mid-height of that layer. The problem is solved by the eigenfunction expansion in conjunction with the transfer matrix technique. The effect of the nonuniform liquid density on the impulsive component of the dynamic response is illustrated in a numerical example in which the linear and cosine distributions of the liquid density are assumed. The response quantities examined include the impulsive pressure, base shear and moments. The results are presented in tabular and graphical forms. It is found that the impulsive pressure distribution along the tank wall is not sensitive to the detailed distribution function of the density, and the base shear and moments for the nonuniform liquid can be estimated by assuming an equivalent uniform liquid density that preserves the total liquid weight. The effect of tank flexibility is assessed by a simple approach in which the response quantities for flexible tanks are evaluated by simplified equations

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

    Science.gov (United States)

    Camporesi, Roberto

    2011-01-01

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

  13. On the effects of nonlinearities in room impulse response measurements with exponential sweeps

    DEFF Research Database (Denmark)

    Ciric, Dejan; Markovic, Milos; Mijic, Miomir

    2013-01-01

    In room impulse response measurements, there are some common disturbances that affect the measured results. These disturbances include nonlinearity, noise and time variance. In this paper, the effects of nonlinearities in the measurements with exponential sweep-sine signals are analyzed from diff...

  14. Detection and Estimation of Arrivals in Room Impulse Responses by Greedy Sparse Approximation

    DEFF Research Database (Denmark)

    Sturm, Bob L.; Defrance, Guillaume

    2010-01-01

    We investigate the use of greedy sparse approximation for facilitating the time-domain analysis of room impulse responses (RIRs), specifically locating the times and amplitudes of arrivals to not long after the upper bound of the ``mixing time,'' i.e., the time after which there exists in theory...

  15. Computing level-impulse responses of log-specified VAR systems

    NARCIS (Netherlands)

    Wieringa, J.E.; Horvath, C.

    2005-01-01

    Impulse response functions (IRFs) are often used to analyze the dynamic behavior of a vector autoregressive (VAR) system. In many applications of VAR modelling, the variables are log-transformed before the model is estimated. If this is the case, the results of the IRFs do not have a direct

  16. Reliability of estimating the room volume from a single room impulse response

    NARCIS (Netherlands)

    Kuster, M.

    2008-01-01

    The methods investigated for the room volume estimation are based on geometrical acoustics, eigenmode, and diffuse field models and no data other than the room impulse response are available. The measurements include several receiver positions in a total of 12 rooms of vastly different sizes and

  17. Association between impulsivity, reward responsiveness and body mass index in children

    NARCIS (Netherlands)

    Van den Berg, L.; Pieterse, K.; Malik, J.A.; Luman, M.; Willems van Dijk, K.; Oosterlaan, J.; Delemarre-van de Waal, H.A.

    2011-01-01

    Background:Childhood obesity is a major health problem. An association between children's body mass index (BMI) and overeating has been established, but mechanisms leading to overeating are poorly understood. The personality characteristics impulsivity and reward responsiveness may be involved in

  18. A Reduced-Order Model for Evaluating the Dynamic Response of Multilayer Plates to Impulsive Loads

    Science.gov (United States)

    2016-04-12

    Analysis (SFEA) – by Numerical Analysis in Nastran • Dynamic Response Index (DRI) and the Screening Metric • Design Optimization Outline 2016-01-0307...elements method (SFEM) and numerical analysis in Nastran in the following examples. Reduced Order Model (ROM) 2016-01-0307 16UNCLASSIFIED: Distribution...Analysis (SFEA) 2. Validation by Numerical Analysis in Nastran • Applying an impulsive load • Comparing the forced response in frequency domain

  19. Derivation of a new parametric impulse response matrix utilized for nodal wind load identification by response measurement.

    Science.gov (United States)

    Kazemi Amiri, A; Bucher, C

    2015-05-26

    This paper provides new formulations to derive the impulse response matrix, which is then used in the problem of load identification with application to wind induced vibration. The applied loads are inversely identified based on the measured structural responses by solving the associated discrete ill-posed problem. To this end - based on an existing parametric structural model - the impulse response functions of acceleration, velocity and displacement have been computed. Time discretization of convolution integral has been implemented according to an existing and a newly proposed procedure, which differ in the numerical integration methods. The former was evaluated based on a constant rectangular approximation of the sampled data and impulse response function in a number of steps corresponding to the sampling rate, while the latter interpolates the sampled data in an arbitrary number of sub-steps and then integrates over the sub-steps and steps. The identification procedure was implemented for a simulation example as well as an experimental laboratory case. The ill-conditioning of the impulse response matrix made it necessary to use Tikhonov regularization to recover the applied force from noise polluted measured response. The optimal regularization parameter has been obtained by L-curve and GCV method. The results of simulation represent good agreement between identified and measured force. In the experiments the identification results based on the measured displacement as well as acceleration are provided. Further it is shown that the accuracy of experimentally identified load depends on the sensitivity of measurement instruments over the different frequency ranges.

  20. Impulse response measurement in the HgCdTe avalanche photodiode

    Science.gov (United States)

    Singh, Anand; Pal, Ravinder

    2018-04-01

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

  1. K-complexes, spindles, and ERPs as impulse responses: unification via neural field theory.

    Science.gov (United States)

    Zobaer, M S; Anderson, R M; Kerr, C C; Robinson, P A; Wong, K K H; D'Rozario, A L

    2017-04-01

    To interrelate K-complexes, spindles, evoked response potentials (ERPs), and spontaneous electroencephalography (EEG) using neural field theory (NFT), physiology-based NFT of the corticothalamic system is used to model cortical excitatory and inhibitory populations and thalamic relay and reticular nuclei. The impulse response function of the model is used to predict the responses to impulses, which are compared with transient waveforms in sleep studies. Fits to empirical data then allow underlying brain physiology to be inferred and compared with other waves. Spontaneous K-complexes, spindles, and other transient waveforms can be reproduced using NFT by treating them as evoked responses to impulsive stimuli with brain parameters appropriate to spontaneous EEG in sleep stage 2. Using this approach, spontaneous K-complexes and sleep spindles can be analyzed using the same single theory as previously been used to account for waking ERPs and other EEG phenomena. As a result, NFT can explain a wide variety of transient waveforms that have only been phenomenologically classified to date. This enables noninvasive fitting to be used to infer underlying physiological parameters. This physiology-based model reproduces the time series of different transient EEG waveforms; it has previously reproduced experimental EEG spectra, and waking ERPs, and many other observations, thereby unifying transient sleep waveforms with these phenomena.

  2. Quality of sound in large rooms: Alteration of room impulse responses

    Science.gov (United States)

    Linusson, Per

    1993-02-01

    Psychoacoustic testing of Room Impulse Responses (RIR), using editing techniques and listening tests with help of auralization is considered. Using these techniques the question of when the reverberation tail is subjectively diffuse was studied. This question is of great interest, for example for auralization techniques. Binaural Room Impulse Responses (BRIR's) were measured in two positions in a concert hall. Their respective reverberation tails were substituted by editing. Listening tests indicated that even with a connection time of 400 ms, some test persons could consistently detect differences with speech as source signal. With music (piano) as source signal the 'limit' of the diffuse part was somewhere between 200 to 400 ms. In the second listening test an individual reflection was substituted with a diffuse one by editing. Three types of diffuse reflections were used. The results indicated that it is possible to improve the subjective quality with a diffuse reflection. Furthermore the character of the diffuse reflection is significant.

  3. Validation of Infinite Impulse Response Multilayer Perceptron for Modelling Nuclear Dynamics

    Directory of Open Access Journals (Sweden)

    F. Cadini

    2008-01-01

    Full Text Available Artificial neural networks are powerful algorithms for constructing nonlinear empirical models from operational data. Their use is becoming increasingly popular in the complex modeling tasks required by diagnostic, safety, and control applications in complex technologies such as those employed in the nuclear industry. In this paper, the nonlinear modeling capabilities of an infinite impulse response multilayer perceptron (IIR-MLP for nuclear dynamics are considered in comparison to static modeling by a finite impulse response multilayer perceptron (FIR-MLP and a conventional static MLP. The comparison is made with respect to the nonlinear dynamics of a nuclear reactor as investigated by IIR-MLP in a previous paper. The superior performance of the locally recurrent scheme is demonstrated.

  4. Design of optical finite impulse response filter generating arbitrary spectrum output

    Science.gov (United States)

    Saha, Arijit; Bhattacharya, Kallol; Chakraborty, Ajoy Kumar

    2015-06-01

    In the present communication, a procedure for the synthesis of an optical finite impulse response (FIR) birefringent filter generating arbitrary spectral output is presented. The basic filter consists of a cascaded system of n identical retarders between two polarizers at the two ends. A mathematical model of the optical FIR filter is introduced using the FIR theory of digital filter design. The parameters determined by the synthesis procedure are the angles of the optic axes of the individual crystals and the angle of the output polarizer. Classical FIR filter design method along with the optical backward transfer technique has been used. Two different arbitrarily specified spectral output profiles have been studied. However, the method is equally applicable for any periodic transfer function whose corresponding impulse response is real and causal.

  5. A binaural advantage in the subjective modulation transfer function with simple impulse responses

    DEFF Research Database (Denmark)

    Thompson, Eric Robert; Dau, Torsten

    2008-01-01

    into account that humans listen with two ears. There can be large interaural phase differences in the modulation transfer functions, which can create detectable interaural level difference fluctuations. Measurements were made to determine whether these interaural modulation phase differences can be used......The speech transmission index (STI) has been a popular method for predicting speech intelligibility in rooms. It is based on the magnitude of the modulation transfer function, which can be derived from the impulse response of the room and the background noise levels. However, it does not take...... to enhance the detectability of sinusoidal intensity modulations imposed on a broadband noise carrier and then convolved with simple, dichotic impulse responses. The results show that there can be a significant advantage to listening with two ears over listening with just one. Some further investigations...

  6. Validation of Infinite Impulse Response Multilayer Perceptron for Modelling Nuclear Dynamics

    International Nuclear Information System (INIS)

    Cadini, F.; Zio, E.; Pedroni, N.

    2007-01-01

    Artificial neural networks are powerful algorithms for constructing nonlinear empirical models from operational data. Their use is becoming increasingly popular in the complex modeling tasks required by diagnostic, safety, and control applications in complex technologies such as those employed in the nuclear industry. In this paper, the nonlinear modeling capabilities of an infinite impulse response multilayer perceptron (IIR-MLP) for nuclear dynamics are considered in comparison to static modeling by a finite impulse response multilayer perceptron (FIR-MLP) and a conventional static MLP. The comparison is made with respect to the nonlinear dynamics of a nuclear reactor as investigated by IIR-MLP in a previous paper. The superior performance of the locally recurrent scheme is demonstrated

  7. An Efficient Channel Model for OFDM and Time Domain Single Carrier Transmission Using Impulse Responses

    Directory of Open Access Journals (Sweden)

    Tariq Jamil Saifullah Khanzada

    2012-01-01

    Full Text Available The OFDM (Orthogonal Frequency Division Multiplexing is well-known, most utilized wideband communication technique of the current era. SCT (Single Carrier Transmission provides equivalent performance in time domain while decision equalizer is implemented in frequency domain. SCT annihilates the ICT (Inter Carrier Interference and the PAPR (Peak to Average Power Ratio which is inherent to OFDM and degrades its performance in time varying channels. An efficient channel model is presented in this contribution, to implement OFDM and SCT in time domain using impulse responses. Both OFDM and SCT models are derived dialectically to model the channel impulse responses. Our model enhances the performance of time domain SCT compared with OFDM and subsides the PAPR and ICI problems of OFDM. SCT is implemented at symbol level contained in blocks. Simulation results implementing Digital Radio Monadiale (DRM assert the performance gain of SCT over OFDM.

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

    Science.gov (United States)

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

    1976-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Kathrin Schag

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

  10. Dose-response relationship of autonomic nervous system responses to individualized training impulse in marathon runners.

    Science.gov (United States)

    Manzi, Vincenzo; Castagna, Carlo; Padua, Elvira; Lombardo, Mauro; D'Ottavio, Stefano; Massaro, Michele; Volterrani, Maurizio; Iellamo, Ferdinando

    2009-06-01

    In athletes, exercise training induces autonomic nervous system (ANS) adaptations that could be used to monitor training status. However, the relationship between training and ANS in athletes has been investigated without regard for individual training loads. We tested the hypothesis that in long-distance athletes, changes in ANS parameters are dose-response related to individual volume/intensity training load and could predict athletic performance. A spectral analysis of heart rate (HR), systolic arterial pressure variability, and baroreflex sensitivity by the sequences technique was investigated in eight recreational athletes during a 6-mo training period culminating with a marathon. Individualized training load responses were monitored by a modified training impulse (TRIMP(i)) method, which was determined in each athlete using the individual HR and lactate profiling determined during a treadmill test. Monthly TRIMP(i) steadily increased during the training period. All the ANS parameters were significantly and very highly correlated to the dose of exercise with a second-order regression model (r(2) ranged from 0.90 to 0.99; P baroreflex sensitivity resembled a bell-shaped curve with a minimum at the highest TRIMP(i), whereas low-frequency oscillations of HR and systolic arterial pressure variability and the low frequency (LF)-to-high frequency ratio resembled an U-shaped curve with a maximum at the highest TRIMP(i). The LF component of HRV assessed at the last recording session was significantly and inversely correlated to the time needed to complete the nearing marathon. These results suggest that in recreational athletes, ANS adaptations to exercise training are dose related on an individual basis, showing a progressive shift toward a sympathetic predominance, and that LF oscillations in HRV at peak training load could predict athletic achievement in this athlete population.

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

    Science.gov (United States)

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

    2015-09-01

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

  12. Effect of delayed response in growth on the dynamics of a chemostat model with impulsive input

    International Nuclear Information System (INIS)

    Jiao Jianjun; Yang Xiaosong; Chen Lansun; Cai Shaohong

    2009-01-01

    In this paper, a chemostat model with delayed response in growth and impulsive perturbations on the substrate is considered. Using the discrete dynamical system determined by the stroboscopic map, we obtain a microorganism-extinction periodic solution, further, the globally attractive condition of the microorganism-extinction periodic solution is obtained. By the use of the theory on delay functional and impulsive differential equation, we also obtain the permanent condition of the investigated system. Our results indicate that the discrete time delay has influence to the dynamics behaviors of the investigated system, and provide tactical basis for the experimenters to control the outcome of the chemostat. Furthermore, numerical analysis is inserted to illuminate the dynamics of the system affected by the discrete time delay.

  13. Characterization of subscriber local loop by measures and analysis of frequency and impulse responses

    Science.gov (United States)

    Costa, João C. W. A.; Reis, Jacklyn; Negrão, Igor; Castro, Agostinho; de Souza, Lamartine V.; Ericson, Klas; Lindqvist, Fredrik; Rius I Riu, Jaume

    2006-10-01

    This paper presents methodologies that could be used for characterizing subscriber telephone loops that carry DSL services (ADSL and ADSL2+), by determination and analysis of frequency response, time domain reflectometry, and impulse response of the line. From this analysis, the subscriber loop length, identification and location of impairments such as bridged taps, gauge changes, and open ended termination across the line are carried out. To verify the methodologies presented, results obtained from measurements are drawn and compared to results obtained from computational simulations.

  14. Usage of measured reverberation tail in a binaural room impulse response synthesis

    DEFF Research Database (Denmark)

    Markovic, Milos; Olesen, Søren Krarup; Madsen, Esben

    2011-01-01

    The aim of the modern communication technologies is an immersive experience. One of the applications that should provide the feeling of being together and sharing the same environment during the communication process is BEAMING. The goal of this paper is to improve audible spatial impression...... utilizing correct acoustical properties of the specific environments. Binaural room impulse response (BRIR) synthesis represents one of the main tasks in the binaural auralization. When the BRIRs are simulated, high order reflections (reverberation tail) are usually modeled statistically because of the high...

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

    Science.gov (United States)

    Camporesi, Roberto

    2011-06-01

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

  16. Evidence for a common origin of the electrons responsible for the impulsive X-ray and type III radio bursts.

    Science.gov (United States)

    Kane, S. R.

    1972-01-01

    Observations of impulsive solar flare X-rays greater than or about equal to 10 keV made with the OGO-5 satellite are compared with ground-based measurements of type III solar radio bursts in 10- to 580-MHz range. It is shown that the times of maxima of these two emissions, when detectable, agree within about 18 sec. This maximum time difference is comparable to that between the maxima of the impulsive X-ray and impulsive microwave bursts. In view of the various observational uncertainties, it is argued that the observations are consistent with the impulsive X-ray, impulsive microwave, and type III radio bursts being essentially simultaneous. The observations are also consistent with 10- to 100-keV electron streams being reponsible for the type III emission. The observations indicate that the non-thermal electron groups responsible for the impulsive X-ray, impulsive microwave, and type III radio bursts are accelerated simultaneously in essentially the same region of the solar atmosphere.

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

    Science.gov (United States)

    Wang, H.; Cheng, J.

    2017-12-01

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

  18. Time series analysis of wind speed using VAR and the generalized impulse response technique

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, Bradley T. [Area of Information Systems and Quantitative Sciences, Rawls College of Business and Wind Science and Engineering Research Center, Texas Tech University, Lubbock, TX 79409-2101 (United States); Kruse, Jamie Brown [Center for Natural Hazard Research, East Carolina University, Greenville, NC (United States); Schroeder, John L. [Department of Geosciences and Wind Science and Engineering Research Center, Texas Tech University, Lubbock, TX (United States); Smith, Douglas A. [Department of Civil Engineering and Wind Science and Engineering Research Center, Texas Tech University, Lubbock, TX (United States)

    2007-03-15

    This research examines the interdependence in time series wind speed data measured in the same location at four different heights. A multiple-equation system known as a vector autoregression is proposed for characterizing the time series dynamics of wind. Additionally, the recently developed method of generalized impulse response analysis provides insight into the cross-effects of the wind series and their responses to shocks. Findings are based on analysis of contemporaneous wind speed time histories taken at 13, 33, 70 and 160 ft above ground level with a sampling rate of 10 Hz. The results indicate that wind speeds measured at 70 ft was the most variable. Further, the turbulence persisted longer at the 70-ft measurement than at the other heights. The greatest interdependence is observed at 13 ft. Gusts at 160 ft led to the greatest persistence to an 'own' shock and led to greatest persistence in the responses of the other wind series. (author)

  19. Single passband microwave photonic filter using continuous-time impulse response.

    Science.gov (United States)

    Huang, Thomas X H; Yi, Xiaoke; Minasian, Robert A

    2011-03-28

    A single passband microwave photonic signal processor based on continuous time impulse response that has high resolution, multiple-taps and baseband-free response as well as exhibiting a square-top passband and tunability, is presented. The design and synthesis of the frequency response are based on a full systematic model for single passband microwave photonic filters to account for arbitrary spectrum slice shapes, which for the first time investigates the combined effects from both the dispersion-induced carrier suppression effect and the RF decay effect due to the spectrum slice width, to enable the optimum design to be realized by utilizing the carrier suppression effect to improve the filter performance. Experimental results demonstrate a high order microwave filter showing high resolution single passband filtering as well as exhibiting reconfiguration, square-top passband and tunability, for the first time to our best knowledge.

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

    Science.gov (United States)

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

    2018-01-01

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

  1. Channel Impulse Response Estimation in IEEE 802.11p via Data Fusion and MMSE Estimator

    Directory of Open Access Journals (Sweden)

    Giulio Ministeri

    2015-01-01

    Full Text Available Tracking the channel impulse response in systems based on the IEEE 802.11p standard, the most widely accepted standard for the physical layer in vehicular area networks (VANETs, is still an open research topic. In this paper we aim to improve previously proposed channel estimators by utilizing data aided algorithm that includes the channel decoding to enhance the quality of the estimated data. Moreover we propose a novel technique that exploits information provided by external sensors like GPS or speedometer, usually present in vehicles. The algorithm proposed so far has been analyzed in non-line-of-sight link conditions; in this paper we present an analysis of performances in the line-of-sight condition as well. Simulations show that both proposals give considerable improvements in terms of packet error rate and channel estimation error in the highway scenario which is surely the most stressing environment for the channel response tracker.

  2. Frequency-modulated impulse response photothermal detection through optical reflectance. 2: Experimental.

    Science.gov (United States)

    Power, J F; Mandelis, A

    1988-08-15

    A fast thermoreflectance impulse response photothermal imager was assembled and tested with several solid materials [quartz, stainless steel, and polyvinylidene difluoride (PVDF)I. The instrument was found to yield quantitative data in agreement with Green's function theoretical models of time domain heat conduction. The FM chirp laser intensity modulation technique used in these experiments gave wide bandwidth photothermal signals and was found to be only limited by the FFT instrumentation frequency response (100 kHz). Thermal diffusivities were calculated, while thermal lensing and thermoelastic effects were further observed. The imager was thus shown to be capable of replacing pulsed laser devices for truly nondestructive applications with materials with low damage threshold to optical pulses.

  3. Highly reconfigurable microwave photonic single-bandpass filter with complex continuous-time impulse responses.

    Science.gov (United States)

    Xue, Xiaoxiao; Zheng, Xiaoping; Zhang, Hanyi; Zhou, Bingkun

    2012-11-19

    We propose a novel structure of complex-tap microwave photonic filter (MPF) employing an incoherent broadband optical source (BOS) and a programmable optical spectrum processor. By tailoring the optical spectral amplitude and phase, arbitrary complex continuous-time impulse responses of the MPF can be constructed. Frequency responses with a single flat-top, highly chirped, or arbitrary-shape passband are demonstrated, respectively. The passband center can also be tuned in a wide range only limited by the opto-electrical devices. To the best of our knowledge, it is the first demonstration of an incoherent-BOS-based MPF which is single-bandpass, widely tunable, and highly reconfigurable with complex taps.

  4. An objective measure for the sensitivity of room impulse response and its link to a diffuse sound field.

    Science.gov (United States)

    Prislan, Rok; Brunskog, Jonas; Jacobsen, Finn; Jeong, Cheol-Ho

    2014-10-01

    This study is relevant to acoustic measurements in reverberation rooms such as measurements of sound transmission, sound absorption, and sound power levels of noise sources. The study presents a quantitative measure for the diffuseness in a room, which is first introduced theoretically and subsequently examined experimentally. The sensitivity of a room due to changes in the initial conditions is quantified by measuring a pair of impulse responses in a room differing only in the sound source position. Such changes are linked to mixing and the diffuse sound field. The measure is based on the maximum of the absolute value of the cross-correlation between the time windowed sections of the two impulse responses. By integrating this quantity normalized by the energy of the impulse response of the room, a single number rating is obtained. Results based on three sets of experiments indicate that the diffusers and absorbers in the room influence the proposed sensitivity measures systematically.

  5. Implementasi Filter Finite Impulse Response (FIR Window Hamming dan Blackman menggunakan DSK TMS320C6713

    Directory of Open Access Journals (Sweden)

    LITA LIDYAWATI

    2016-02-01

    Full Text Available ABSTRAK Filter didefinisikan sebagai proses atau rangkaian yang melewatkan pita frekuensi tertentu yang diinginkan dan meredam pita frekuensi lainnya. Salah satu metode perancangan filter digital Finite Impulse Response (FIR adalah metode windowing. Dalam penelitian ini digunakan jenis window Hamming dan Blackman. Simulasi dilakukan dengan menggunakan software Matlab dengan memasukan frekuensi passband, frekuensi stopband, ripple passband, dan stopband attenuation. Dengan frekuensi sampling sebesar 15000 Hz, frekuensi passband sebesar 3000 Hz, frekuensi stopband sebesar 5000 Hz. Setelah simulasi dilakukan implementasi filter dengan parameter yang sama menggunakan DSK TMS 320C6713 dengan bantuan software CCS. Simulasi dan implementasi dilakukan pada semua band frekuensi. Hasil pengujian terhadap implementasi filter adalah respon magnitude, frekuensi cut-off, bandwidth, dan faktor kualitas dengan hasil simulasi tidak menunjukkan perbedaan yang signifikan. Kata kunci: filter digital, windowing, Hamming, Blackman, frekuensi cut-off . ABSTRACT Filter is defined as a process or series that skip certain desired frequency band and other frequency bands drown. One method of designing a digital filter Finite Impulse Response (FIR is a windowing method. This study used the type of window Hamming and Blackman. Simulations performed using Matlab software by inserting a frequency passband, stopband frequency, passband ripple, and stopband attenuation. With a sampling frequency of 15,000 Hz, a frequency of 3000 Hz passband, stopband frequency of 5000 Hz. After the simulation is completed, implementation of the filter with the same parameters using TMS 320C6713 DSK with the help of software CCS. Simulation and implmentasi performed on all frequency bands. The test results of the implementation of the filter is the Magnitude response, the cut-off frequency, bandwidth, and quality factor with simulation results showed no significant difference. Keywords: digital

  6. A note on errors and signal to noise ratio of binary cross-correlation measurements of system impulse response

    International Nuclear Information System (INIS)

    Cummins, J.D.

    1964-02-01

    The sources of error in the measurement of system impulse response using test signals of a discrete interval binary nature are considered. Methods of correcting for the errors due to theoretical imperfections are given and the variance of the estimate of the system impulse response due to random noise is determined. Several topics related to the main topic are considered e.g. determination of a theoretical model from experimental results. General conclusions about the magnitude of the errors due to the theoretical imperfections are made. (author)

  7. The generation of shared cryptographic keys through channel impulse response estimation at 60 GHz.

    Energy Technology Data Exchange (ETDEWEB)

    Young, Derek P.; Forman, Michael A.; Dowdle, Donald Ryan

    2010-09-01

    Methods to generate private keys based on wireless channel characteristics have been proposed as an alternative to standard key-management schemes. In this work, we discuss past work in the field and offer a generalized scheme for the generation of private keys using uncorrelated channels in multiple domains. Proposed cognitive enhancements measure channel characteristics, to dynamically change transmission and reception parameters as well as estimate private key randomness and expiration times. Finally, results are presented on the implementation of a system for the generation of private keys for cryptographic communications using channel impulse-response estimation at 60 GHz. The testbed is composed of commercial millimeter-wave VubIQ transceivers, laboratory equipment, and software implemented in MATLAB. Novel cognitive enhancements are demonstrated, using channel estimation to dynamically change system parameters and estimate cryptographic key strength. We show for a complex channel that secret key generation can be accomplished on the order of 100 kb/s.

  8. Axisymmetrical impulsive responses of an infinite circular cylindrical shell filled with liquid

    International Nuclear Information System (INIS)

    Ujihashi, Sadayuki; Matsumoto, Hiroyuki; Nakahara, Ichiro; Shigeta, Masayuki.

    1986-01-01

    In this paper, dynamic interaction phenomena on solid and liquid interfaces are discussed. Axisymmetrical responses of an infinite circular cylindrical shell perfectly filled with liquid are analyzed, based on Fluegge's theory for a circular cylindrical shell and the potential theory for the ideal fluid under conditions of the impulsive external band pressure given on the outer surface of the shell. The deflection and the moment of the shell and the pressure in the fluid are evaluated by using the numerical inversion of the Laplace transformation method. The approximate solution for the shell with an equivalent mass on it is analyzed and is evaluated, based on the solution for the solid and liquid interaction. (author)

  9. Volatility transmission and volatility impulse response functions in European electricity forward markets

    International Nuclear Information System (INIS)

    Le Pen, Yannick; Sevi, Benoit

    2008-01-01

    Using daily data from March 2001 to June 2005, we estimate a VAR-BEKK model and find evidence of return and volatility spillovers between the German, the Dutch and the British forward electricity markets. We apply Hafner and Herwartz [2006, Journal of International Money and Finance 25, 719-740] Volatility Impulse Response Function(VIRF) to quantify the impact of shock on expected conditional volatility. We observe that a shock has a high positive impact only if its size is large compared to the current level of volatility. The impact of shocks are usually not persistent, which may be an indication of market efficiency. Finally, we estimate the density of the VIRF at different forecast horizon. These fitted distributions are asymmetric and show that extreme events are possible even if their probability is low. These results have interesting implications for market participants whose risk management policy is based on option prices which themselves depend on the volatility level. (authors)

  10. Length Variation Effect of the Impulse Response Model of a Secondary Path in Embedded Control

    Directory of Open Access Journals (Sweden)

    Young-Sup Lee

    2016-01-01

    Full Text Available This study presents theoretical and experimental investigation on the length variation effect of the impulse response function (IRF for the secondary path model in active noise control using an embedded control board. A narrowband sweep noise was the disturbance for control in a duct with the length of 1800 mm. The IRF model incorporated into an adaptive feedforward filtered-x LMS (FxLMS algorithm was then analyzed in the variation of its length in terms of the mean square error, computation complexity, stability requirement, and attenuation performance before and after control. The FxLMS algorithm with various IRF lengths was implemented in a dSPACE DS1104 embedded control board for the real-time control. Finally the most reasonable IRF length, considering the computation complexity and performance, can be determined through the systematic investigation. The results in this study can be used for practical active noise control systems.

  11. An Exploratory Analysis of Sound Field Characteristics using the Impulse Response in a Car Cabin

    Directory of Open Access Journals (Sweden)

    Yoshiharu Soeta

    2018-03-01

    Full Text Available Sound environments in cars are becoming quieter and receiving attention because of the prevalence of low-noise engines such as hybrid and electric engines and the manifestation of automated driving. Although the car cabin has potential as a listening space, its acoustic quality has not been examined in detail. The present study investigated sound field characteristics in the car cabin using acoustic parameters obtained by impulse response analysis. In particular, effects of the passenger position, open windows and the use of an air conditioner on acoustic parameters were investigated. The passenger position affected the sound strength at low frequencies. Rear seats, except for the rear central seat, had lower interaural correlation than the front seats, suggesting that rear seats have more diffused sound fields. The opening of windows and use of air conditioners attenuated the ratio of early- and late-arriving energy at high frequencies, suggesting a loss of clarity for music.

  12. Low-complexity Wireless Monitoring of Respiratory Movements Using Ultra-wideband Impulse Response Estimation

    KAUST Repository

    Sana, Furrukh

    2014-03-01

    In this paper; we present a comprehensive scheme for wireless monitoring of the respiratory movements in humans. Our scheme overcomes the challenges low signal-to-noise ratio, background clutter and high sampling rates. It is based on the estimation of the ultra-wideband channel impulse response. We suggest techniques for dealing with background clutter in situations when it might be time variant. We also present a novel methodology for reducing the required sampling rate of the system significantly while achieving the accuracy offered by the Nyquist rate. Performance results from simulations conducted with pre-recorded respiratory signals demonstrate the robustness of our scheme for tackling the above challenges and providing a low-complexity solution for the monitoring of respiratory movements.

  13. The average impulse response of a rough surface and its applications. [in radar altimetry

    Science.gov (United States)

    Brown, G. S.

    1977-01-01

    This paper is concerned with the theoretical model for short pulse scattering from a statistically random planar surface with particular application to current state of the art radar altimetry. A short review of the assumptions inherent in the convolutional model is presented. Simplified expressions are obtained for both the impulse response and the average backscattered power for near normal incidence under the assumptions common to satellite radar altimetry systems. In particular, it is shown that the conventional two-dimensional surface integration can be reduced to a closed form solution. Two applications of these results are presented relative to radar altimetry, namely, radar antenna pointing angle determination and altitude bias correction for pointing angle and surface roughness effects. It is also shown that these results have direct application to the analysis of the two frequency system proposed by Weissman, and a possible combined long pulse altimeter and two frequency system is suggested.

  14. A new definition of boundary point between early reflections and late reverberation in room impulse responses.

    Science.gov (United States)

    Hidaka, Takayuki; Yamada, Yoshinari; Nakagawa, Takehiko

    2007-07-01

    The early reflections in the room impulse response are usually defined as those observed within the initial 80 ms after the arrival of the direct sound, after which time the sound field is called reverberant. This number was chosen from measurements of other functions in a limited number of halls. In order to give an objective foundation to this time separation and to establish a physical indicator for it, a new method is proposed that defines a "transition time t(L)," which is the time at which the energy correlation between the direct plus initial sound and the subsequent decaying sound first achieves a specified low value. For various halls this number is shown and its relevance as a new parameter is discussed.

  15. Impulse Response of a 36-Core Few-Mode Photonic Lantern Hybrid Spatial-Multiplexer

    DEFF Research Database (Denmark)

    Rommel, Simon; Mendinueta, José Manuel Delgado; Klaus, Werner

    2017-01-01

    of spatial multiplexers (SMUXs) are important. In this work, we characterize the impulse response of a 36-core three-mode photonic lantern SMUX, similar to [4], with no mode selectivity, coupled to 2.9m 36-core three-mode fiber including a splice, using a spatially diverse optical vector network analyzer......Space division multiplexing (SDM) using fibers with multiple cores and/or supporting multiple modes has become an essential technology to support Pbit/s transmissions in a single fiber [1,2]. Despite significant mode-mixing in few-mode fibers (FMF), the original signals can be recovered through...... multiple-input multiple-output (MIMO) equalization, provided mode-dependent loss (MDL) is small [3]. Furthermore, mode scrambling at the transmitter improves tolerance to MDL and maximizes system capacity if all supported modes are used to transmit information [3]. Thus, the MDL and mode mixing properties...

  16. Implementation of high-speed–low-power adaptive finite impulse response filter with novel architecture

    Directory of Open Access Journals (Sweden)

    Manish Jaiswal

    2015-03-01

    Full Text Available An energy efficient high-speed adaptive finite impulse response filter with novel architecture is developed. Synthesis results along with novel architecture on different complementary metal–oxide semiconductor (CMOS families are presented. Analysis is performed using Artix-7, Spartan-6 and Virtex-4 for most popular adaptive least mean square filter for different orders such as N = 8, 16, 32. The presented work is done using MATLAB (2013b and Xilinx (14.2. From the synthesis results, it can be found that CMOS (28 nm achieves the lowest power and critical path delay compared to others, and thus proves its efficiency in terms of energy. Different parameters are considered such as look up tables and input–output blocks, along with their optimised results.

  17. Evaluation of the autonomic neuropathy function immediately after a change to upright posture using the impulse response function; Impulse oto kansu wo mochiita shisei henkan katoki ni okeru jiritsu shinkei kino hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, K. [Nagoya City University, Nagoya (Japan); Moyoshi, M.; Takata, K. [Daido Institute of Technology, Nagoya (Japan); Watanabe, Y. [Toyota College of Technology, Aichi (Japan)

    1997-05-20

    Autonomic neuropathy function immediately after a change to upright posture has been evaluated by applying transient response function of the system to the blood regulation system. The impulse response function was determined from the change in heart rate before postural change to the upright posture, and was compared with the transient change immediately after a change to the upright posture. The time series of R-R interval of electrocardiogram was used as the time series of the change in heart rate. To determine the impulse response function, an autoregressive model was applied to the R-R interval time series. The impulse response function at the steady state is a transient reaction at the impulse stimulation added to the blood regulation system. The R-R interval decreases rapidly by the autonomic neuropathy reaction in which the blood is rapidly transferred into the legs immediately after a change to upright posture. There is a close correlation between the initial temporary decrease in R-R interval and the impulse response function derived from the change in heart rate immediately after a change to the upright posture. Accordingly, the blood regulation and autonomic neuropathy functions can be evaluated by the impulse response function without actual standing test and load of tested persons. 9 refs., 3 figs., 1 tab.

  18. Pulsed-laser-activated impulse response encoder: Sensitive detection of surface elastic waves on biomimetic microsized gel spheres

    Science.gov (United States)

    Yasukuni, Ryohei; Fukushima, Ryosuke; Iino, Takanori; Hosokawa, Yoichiroh

    2017-11-01

    A femtosecond-laser-induced impulsive force was applied to microsized calcium alginate (CaAlg) gel spheres as an external force to excite elastic waves. To evaluate elasticity, atomic force microscopy (AFM) was applied to detect vibration propagation. The sphere size dependence of the vibration was well reproduced by finite element method (FEM) simulation for pressure waves and surface acoustic waves. The obtained results indicate that the pulsed-laser-activated impulse response encoder (PLAIRE) enables the sensitive detection of elasticities, not only on inside but also on the surface.

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

    Science.gov (United States)

    Camporesi, Roberto

    2016-01-01

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

  20. Analysis of sensor impulse response effects on Cramèr–Rao lower bounds for signal parameter estimators

    Directory of Open Access Journals (Sweden)

    Ephraim S. Gower

    2014-12-01

    Full Text Available In this study, a generic analysis of sensor impulse response effects on linearly filtered channel noise is presented to illustrate the resulting variations to the Cramèr–Rao lower bounds (CRLBs of signal parameter estimators in signal processing and communication applications. The authors start by deriving the density function of a filtered signal, which is shown to be a mixture density, and hence the exact expressions for the mean and variance. Simulation results are used to confirm the derivations, which are then used to investigate the effects of impulse response length and variance, as well as channel noise length and variance effects on the resulting CRLBs. Results indicate that for non-zero-mean channel noise and impulse responses, the resulting mean of filtered noise can be relatively large causing adverse deviations to parameter estimations. The filtered noise variance is shown to be proportional to the impulse response energy, where for long duration of signal capture the CRLB is significantly increased.

  1. Impulse-response analysis of monetary policy – Visegád group countries case

    Directory of Open Access Journals (Sweden)

    Kateřina Myšková

    2013-01-01

    Full Text Available In this paper, we focus on comparability of monetary policies of Visegrád group countries (V4. Main objective of central banks function in V4 countries lies in maintaining price stability. For this purpose, inflation targeting regime is realized in a medium-term focus in V4, which means that there is a certain lag between monetary policy operation and its influence on an inflation target. Central bank does not have a direct impact on its ultimate goals. Therefore, any monetary policy analysis and assumption of its effectiveness comes out from an essential existence of a working transmission mechanism. Thus, changes in settings of monetary policy instruments have to be able to inflict causal changes on intermediary markets and via these markets on target markets. This situation can be modeled by the vector autoregressive (VAR model with suitable variables. Our main task is to compare a relationship between VAR model responses to predefined impulses for all V4 pairs. We use calibration technique for this purpose. Specifically, we will utilize one-dimensional calibration model with a linear calibration function for deriving unknown parameters. Moreover, we will test a significance of estimated parameters. We distinguish between model parameters for before-crisis- and during-crisis- data, because we suppose that financial crisis affects VAR model parameters significantly. Different responses in each country can mean the inability of the common monetary policy for V4 at present.

  2. An automatic model-building algorithm for sparse approximation of room impulse responses with orthonormal basis functions

    DEFF Research Database (Denmark)

    Vairetti, G.; van Waterschoot, T.; Moonen, M.

    2014-01-01

    include knowledge about the room resonances as a set of poles, which appear nonlinearly in the structure. A novel algorithm is pro-posed, that avoids this nonlinear problem by iteratively estimating the poles and building the model. Some of the properties of OBF models, such as orthogonality and linearity......Orthonormal Basis Function (OBF) models are used to define stable fixed-poles infinite impulse response filter structures that allow to incorporate knowledge about the resonant characteristics of a stable, causal and linear system. In the approximation of a room impulse response, OBF models can......-in-the-parameters, are exploited and the final model has the favorable property of being scalable. The OBF model provides a longer response than the all-zero model and is particularly suited in approximating the early response and the predominant resonances for relatively small model orders....

  3. Transcriptional and temporal response of Populus stems to gravi-stimulation.

    Science.gov (United States)

    Zinkgraf, Matthew; Gerttula, Suzanne; Zhao, Shutang; Filkov, Vladimir; Groover, AndrewLi

    2018-02-26

    Plants modify development in response to external stimuli, to produce new growth that is appropriate for environmental conditions. For example, gravi-stimulation of leaning branches in angiosperm trees results in modifications of wood development, to produce tension wood that pulls leaning stems upright. Here, we use gravi-stimulation and tension wood response to dissect the temporal changes in gene expression underlying wood formation in Populus stems. Using time-series analysis of 7 time points over a 14-day experiment, we identified 8919 genes that were differentially expressed between tension wood (upper) and opposite wood (lower) sides of leaning stems. Clustering of differentially expressed genes showed four major transcriptional responses, including gene clusters whose transcript levels were associated with two types of tissue-specific impulse responses that peaked at about 24 - 48 hours, and gene clusters with sustained changes in transcript levels that persisted until the end of the 14-day experiment. Functional enrichment analysis of those clusters suggests they reflect temporal changes in pathways associated with hormone regulation, protein localization, cell wall biosynthesis and epigenetic processes. Time-series analysis of gene expression is an underutilized approach for dissecting complex developmental responses in plants, and can reveal gene clusters and mechanisms influencing development. This article is protected by copyright. All rights reserved.

  4. Viscoelastic damped response of cross-ply laminated shallow spherical shells subjected to various impulsive loads

    Science.gov (United States)

    Şahan, Mehmet Fatih

    2017-11-01

    In this paper, the viscoelastic damped response of cross-ply laminated shallow spherical shells is investigated numerically in a transformed Laplace space. In the proposed approach, the governing differential equations of cross-ply laminated shallow spherical shell are derived using the dynamic version of the principle of virtual displacements. Following this, the Laplace transform is employed in the transient analysis of viscoelastic laminated shell problem. Also, damping can be incorporated with ease in the transformed domain. The transformed time-independent equations in spatial coordinate are solved numerically by Gauss elimination. Numerical inverse transformation of the results into the real domain are operated by the modified Durbin transform method. Verification of the presented method is carried out by comparing the results with those obtained by the Newmark method and ANSYS finite element software. Furthermore, the developed solution approach is applied to problems with several impulsive loads. The novelty of the present study lies in the fact that a combination of the Navier method and Laplace transform is employed in the analysis of cross-ply laminated shallow spherical viscoelastic shells. The numerical sample results have proved that the presented method constitutes a highly accurate and efficient solution, which can be easily applied to the laminated viscoelastic shell problems.

  5. Impulse-response analysis of planar computed tomography for nondestructive test

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae Cheon; Kim, Seung Ho; Kim, Ho Kyung [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    There have been reported that the use of radiation imaging such as digital radiography, computed tomography (CT), and digital tomosynthesis (DTS) for the nondestructive test (NDT) widely is spreading. These methods have merits and demerits of their own, in terms of image quality and inspection speed. Therefore, image for these methods for NDT should have acceptable image quality and high speed. In this study, we quantitatively evaluate impulse responses of reconstructed images from the filtered backprojection (FBP), which are most widely used in planar computed tomography (pCT) systems. We first evaluate image performance metrics due to the contrast, depth resolution, and then we design the figure of merit including image performance and system parameters, such as tube load and reconstruction speed. The final goal of this study is the application of these methods to the nondestructive test. In order to accomplish it, further study is needed. First of all, the results of the ASF from various numbers of views. Second, the analysis of modulation transfer function, noise power spectrum, and detective quantum efficiency from various angular range and numbers of views.

  6. Lagrangian and energy forms for retrieving the impulse response of the Earth due to random electromagnetic forcing.

    Science.gov (United States)

    Slob, Evert; Weiss, Chester J

    2011-08-01

    We distinguish between trivial and nontrivial differences in retrieving the real or imaginary parts of the Green's function. Trivial differences come from different Green's function definitions. The energy and lagrangian forms constitute nontrivial differences. Magnetic noise sources suffice to extract the quasistatic electromagnetic-field Earth impulse response in the lagrangian form. This is of interest for Earth subsurface imaging. A numerical example demonstrates that all source vector components are necessary to extract a single-field vector component.

  7. The Dynamics of an Impulsive Predator-Prey System with Stage Structure and Holling Type III Functional Response

    Directory of Open Access Journals (Sweden)

    Zhixiang Ju

    2015-01-01

    Full Text Available Based on the biological resource management of natural resources, a stage-structured predator-prey model with Holling type III functional response, birth pulse, and impulsive harvesting at different moments is proposed in this paper. By applying comparison theorem and some analysis techniques, the global attractivity of predator-extinction periodic solution and the permanence of this system are studied. At last, examples and numerical simulations are given to verify the validity of the main results.

  8. Temporal specificity of the initial adaptive response in motor adaptation.

    Directory of Open Access Journals (Sweden)

    Wilsaan M Joiner

    2017-07-01

    Full Text Available Repeated exposure to a novel physical environment eventually leads to a mature adaptive response whereby feedforward changes in motor output mirror both the amplitude and temporal structure of the environmental perturbations. However, adaptive responses at the earliest stages of learning have been found to be not only smaller, but systematically less specific in their temporal structure compared to later stages of learning. This observation has spawned a lively debate as to whether the temporal structure of the initial adaptive response is, in fact, stereotyped and non-specific. To settle this debate, we directly measured the adaptive responses to velocity-dependent and position-dependent force-field perturbations (vFFs and pFFs at the earliest possible stage of motor learning in humans-after just a single-movement exposure. In line with previous work, we found these earliest stage adaptive responses to be more similar than the perturbations that induced them. However, the single-trial adaptive responses for vFF and pFF perturbations were clearly distinct, and the disparity between them reflected the difference between the temporal structure of the perturbations that drove them. Critically, we observed these differences between single-trial adaptive responses when vFF and pFF perturbations were randomly intermingled from one trial to the next within the same block, indicating perturbation response specificity at the single trial level. These findings demonstrate that the initial adaptive responses to physical perturbations are not stereotyped. Instead, the neural plasticity in sensorimotor areas is sensitive to the temporal structure of a movement perturbation even at the earliest stage in learning. This insight has direct implications for the development of computational models of early-stage motor adaptation and the evolution of this adaptive response with continued training.

  9. Eysenck personality inventory: impulsivity/neuroticism and social desirability response set.

    Science.gov (United States)

    Kumari, V

    1996-02-01

    The Hindi version of the Eysenck Personality Inventory and the Trait scale of the Hindi version of the State-Trait Anxiety Inventory were administered to 945 female Indian students (M age = 20.4 yr., SD = 1.4) to study the personalities of those scoring low and high on the Lie scale, and the association of Lie scale scores in the intercorrelation between Impulsivity and Neuroticism under no motivation to fake good. The group with low scores on the Lie scale had lower scores on Impulsivity and higher scores on Neuroticism and Trait Anxiety than a group scoring high on the Lie scale. No association of Lie scale scores was observed with scores on Extraversion. Lie scale scores were differentially associated with scores on Impulsivity and Neuroticism. The need to consider the Lie scale in addition to other scales in studies of personality is emphasised.

  10. Measurement of the responses of polyurethane and CONFOR(TM) foams and the development of a system identification technique to estimate polyurethane foam parameters from experimental impulse responses

    Science.gov (United States)

    Sundaram, Vaidyanadan

    Flexible polyurethane foam is the main cushioning element used in car seats. Optimization of an occupied seat's static and dynamic behavior requires models of foam that are accurate over a wide range of excitation and pre-compression conditions. Experiments were conducted to measure the response of foam over a wide range of excitation which include slowly varying uniaxial compression tests on a 3 inch cube foam sample, base excitation and impulse excitation test on a foam-mass system. The foam used was the same in all of the experiments, thus obtaining all the responses on the same foam sample which helps eliminate the sample to sample variation. Similar efforts were taken to conduct impulse and base excitation tests on CONFOR(TM) foam to help in future modeling efforts of CONFOR(TM) foam. All the experimental protocols and data pre-processing protocols along with results are presented. Previous researcher developed a linear model for a single-degree of freedom foam-mass system subjected to an impulsive excitation. Free response data from impulse tests on a foam-mass system with different masses was used to identify model parameters at various pre-compression levels (settling points). The free response of the system was modeled as a Prony series (sum of exponentials) whose parameters can be related to the parameters in the foam-mass system model. Models identified from tests at one settling point performed poorly when used to predict the response at other settling points. In this research, a method is described to estimate the parameters of a global model of the foam behavior from data gathered in a series of impulse tests at different settling points. The global model structure includes a nonlinear elastic term and a hereditary viscoelastic term. The model can be used to predict the settling point for each mass used and, by expanding the model about that settling point, local linear models of the response to impulsive excitation can be derived. From this analysis

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

    Science.gov (United States)

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

    2010-10-01

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

  12. Temporal response of bone to unloading

    Energy Technology Data Exchange (ETDEWEB)

    Globus, R.K.; Bikle, D.D.; Morey-Holton, E.

    1986-02-01

    A model of weightlessness in which the hindlimbs of rats are elevated by their tails at a 40 degrees angle to unload the hindlimbs while maintaining normal weight bearing on the forelimbs has been used to simulate certain conditions of space flight. When we used this model in growing rats, we found that growth in bone weight ceased by 1 week in the hindlimbs and lumbar vertebrae, whereas growth in bone weight in the forelimbs and cervical vertebrae remained unaffected. Within 2 weeks, however, the accretion of bone weight in the hindlimbs and lumbar vertebrae returned to normal despite continued skeletal unloading. Since bone weight in the growing rat is primarily determined by bone formation (bone resorption is modest), we investigated the effects of selective skeletal unloading on bone formation during 2 weeks of hindlimb elevation using radioisotope incorporation (with /sup 45/Ca and (/sup 3/H)proline) and histomorphometry (with tetracycline labeling). The studies using radioisotope incorporation showed that bone formation was inhibited by the fifth day of skeletal unloading. By the 10th to 12th day, bone formation had returned toward normal. In comparison with cortical bone, cancellous bone (lumbar vertebrae and proximal tibiae) incorporated more /sup 45/Ca and (/sup 3/H)proline (indicating greater metabolic activity) and had a greater absolute response to skeletal unloading. The results of these studies were confirmed by histomorphometric measurements of bone formation using triple tetracycline labeling. We conclude that this model of simulated weightlessness results in an initial inhibition of bone formation in the unloaded bones. This temporary cessation of bone formation is followed by a cessation in the accretion of bone weight, which then resumes at a normal rate by 14 days despite continued skeletal unloading.

  13. Temporal response of laser power standards with natural convective cooling.

    Science.gov (United States)

    Xu, Tao; Gan, Haiyong; Yu, Jing; Zang, Erjun

    2016-01-25

    Laser power detectors with natural convective cooling are convenient to use and hence widely applicable in a power range below 150 W. However, the temporal response characteristics of the laser power detectors need to be studied in detail for accurate measurement. The temporal response based on the absolute laser power standards with natural convective cooling is studied through theoretical analysis, numerical simulations, and experimental verifications. Our results show that the response deviates from a single exponential function and that an ultimate response balance is difficult to achieve because the temperature rise of the heat sink leads to continuous increase of the response. To determine the measurement values, an equal time reading method is proposed and validated by the laser power calibrations.

  14. Integrated built-in-test false and missed alarms reduction based on forward infinite impulse response & recurrent finite impulse response dynamic neural networks

    Science.gov (United States)

    Cui, Yiqian; Shi, Junyou; Wang, Zili

    2017-11-01

    Built-in tests (BITs) are widely used in mechanical systems to perform state identification, whereas the BIT false and missed alarms cause trouble to the operators or beneficiaries to make correct judgments. Artificial neural networks (ANN) are previously used for false and missed alarms identification, which has the features such as self-organizing and self-study. However, these ANN models generally do not incorporate the temporal effect of the bottom-level threshold comparison outputs and the historical temporal features are not fully considered. To improve the situation, this paper proposes a new integrated BIT design methodology by incorporating a novel type of dynamic neural networks (DNN) model. The new DNN model is termed as Forward IIR & Recurrent FIR DNN (FIRF-DNN), where its component neurons, network structures, and input/output relationships are discussed. The condition monitoring false and missed alarms reduction implementation scheme based on FIRF-DNN model is also illustrated, which is composed of three stages including model training, false and missed alarms detection, and false and missed alarms suppression. Finally, the proposed methodology is demonstrated in the application study and the experimental results are analyzed.

  15. Dietary restraint and impulsivity modulate neural responses to food in adolescents with obesity and healthy adolescents.

    Science.gov (United States)

    Hofmann, Johannes; Ardelt-Gattinger, Elisabeth; Paulmichl, Katharina; Weghuber, Daniel; Blechert, Jens

    2015-11-01

    Despite alarming prevalence rates, surprisingly little is known about neural mechanisms underlying eating behavior in juveniles with obesity. To simulate reactivity to modern food environments, event-related potentials (ERP) to appetizing food images (relative to control images) were recorded in adolescents with obesity and healthy adolescents. Thirty-four adolescents with obesity (patients) and 24 matched healthy control adolescents watched and rated standardized food and object images during ERP recording. Personality (impulsivity) and eating styles (trait craving and dietary restraint) were assessed as potential moderators. Food relative to object images triggered larger early (P100) and late (P300) ERPs. More impulsive individuals had considerably larger food-specific P100 amplitudes in both groups. Controls with higher restraint scores showed reduced food-specific P300 amplitudes and subjective palatability ratings whereas patients with higher restraint scores showed increased P300 and palatability ratings. This first ERP study in adolescents with obesity and controls revealed impulsivity as a general risk factor in the current obesogenic environment by increasing food-cue salience. Dietary restraint showed paradoxical effects in patients, making them more vulnerable to visual food-cues. Salutogenic therapeutic approaches that deemphasize strict dietary restraint and foster healthy food choice might reduce such paradoxical effects. © 2015 The Obesity Society.

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

    Science.gov (United States)

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

    2018-03-01

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

  17. Periodic Solutions and Homoclinic Bifurcations of Two Predator-Prey Systems with Nonmonotonic Functional Response and Impulsive Harvesting

    Directory of Open Access Journals (Sweden)

    Mingzhan Huang

    2014-01-01

    Full Text Available Two predator-prey models with nonmonotonic functional response and state-dependent impulsive harvesting are formulated and analyzed. By using the geometry theory of semicontinuous dynamic system, we obtain the existence, uniqueness, and stability of the periodic solution and analyse the dynamic phenomenon of homoclinic bifurcation of the first system by choosing the harvesting rate β as control parameter. Besides, we also study the homoclinic bifurcation of the second system about parameter δ on the basis of the theory of rotated vector field. Finally, numerical simulations are presented to illustrate the results.

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

    Science.gov (United States)

    Camporesi, Roberto

    2016-01-01

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

  19. An objective measure for the sensitivity of room impulse response and its link to a diffuse sound field

    DEFF Research Database (Denmark)

    Prislan, Rok; Brunskog, Jonas; Jacobsen, Finn

    2014-01-01

    This study is relevant to acoustic measurements in reverberation rooms such as measurements of sound transmission, sound absorption, and sound power levels of noise sources. The study presents a quantitative measure for the diffuseness in a room, which is first introduced theoretically and sub......- sequently examined experimentally. The sensitivity of a room due to changes in the initial condi- tions is quantified by measuring a pair of impulse responses in a room differing only in the sound source position. Such changes are linked to mixing and the diffuse sound field. The measure is based...

  20. The effect of pulse pile-up on threshold crossing rates in a system with a known impulse response

    International Nuclear Information System (INIS)

    Nikitin, A.V.; Davidchack, R.L.; Armstrong, T.P.

    1998-01-01

    The problem of counting rates in a counting detection system is viewed as a stochastic problem of mean threshold crossing rates for a dynamic system driven by a stationary random force. We present a general formula for calculating the rates of such a system at an arbitrary threshold for all values of event occurrence rates, given that the amplitude distribution of the incoming events and the impulse response of the detection system are known. From a single general formula we derive asymptotic expressions for counting rates at both limits of high and low incoming rates. We give a simple expression for the saturation counting rate of a detection system and show that for a high-order pile-up the average intensity and variation of the incoming signal can be determined by measuring the counting rates at two thresholds. For low incoming rates, we show how the unknown incoming distribution can be computed from the measured pulse-height spectrum. Based on the asymptotic results, we demonstrate how to construct an approximation to the impulse response function of the detection system, which facilitates numerical evaluation of the general formula. In each case, we present a comparison with numerical experiments. Throughout the paper, we illustrate how well-known experimental facts can be deduced from a single general formula. (orig.)

  1. Analysis framework for systematically studying ionospheric response to impulsive events from below

    Science.gov (United States)

    Haaser, Robert A.; Lay, Erin H.; Junor, William

    2017-09-01

    Impulsive phenomena in the Earth's atmosphere produce acoustic and gravity waves which perturb the ionosphere. Such perturbations are often measured using total electron content fluctuations (TEC), derived from ground-based Global Positioning System data. Using TEC data from the Japanese GEONET ground network after the Tōhoku earthquake on 11 March 2011, we demonstrate capabilities of a new framework of methodologies for analyzing ionospheric perturbations. The framework consists of several new techniques: calculating velocity along a single direction to reduce error due to anisotropic propagation, producing normalized bidirectional band-pass spectra that preserve relative timing between various frequencies and allowing a more systematic determination of broadband pulses, and utilizing a wavelet-based technique that considers instantaneous wave phase changes, rather than best fit time differences, to evaluate wave characteristics (speed, direction, and wavelength) within spectral ranges of interest. Using these techniques together decreases subjectivity and reduces errors in attributing fluctuations to given sources. In validating this framework using the Tōhoku case, we consistently identify three kinds of waves: a broad-band pulse (speed: >2000 m/s, max range: >1400 km) arriving in the ionosphere 10-15 min after the quake, acoustic waves following the pulse (period: 3-5 min, speed: 700-1000 m/s, max range: 1400 km) propagating away from the epicenter, consistent with theory and demonstrated in previous studies. This framework also can be applied to other impulsive events in the atmosphere that are more difficult to detect and attribute to sources.

  2. The impact of temporal regularization on estimates of the BOLD hemodynamic response function: a comparative analysis.

    Science.gov (United States)

    Casanova, Ramon; Ryali, Srikanth; Serences, John; Yang, Lucie; Kraft, Robert; Laurienti, Paul J; Maldjian, Joseph A

    2008-05-01

    In fMRI data analysis it has been shown that for a wide range of situations the hemodynamic response function (HRF) can be reasonably characterized as the impulse response function of a linear and time invariant system. An accurate and robust extraction of the HRF is essential to infer quantitative information about the relative timing of the neuronal events in different brain regions. When no assumptions are made about the HRF shape, it is most commonly estimated using time windowed averaging or a least squares estimated general linear model based on either Fourier or delta basis functions. Recently, regularization methods have been employed to increase the estimation efficiency of the HRF; typically these methods produce more accurate HRF estimates than the least squares approach [Goutte, C., Nielsen, F.A., Hansen, L.K., 2000. Modeling the Haemodynamic Response in fMRI Using Smooth FIR Filters. IEEE Trans. Med. Imag. 19(12), 1188-1201.]. Here, we use simulations to clarify the relative merit of temporal regularization based methods compared to the least squares methods with respect to the accuracy of estimating certain characteristics of the HRF such as time to peak (TTP), height (HR) and width (W) of the response. We implemented a Bayesian approach proposed by Marrelec et al. [Marrelec, G., Benali, H., Ciuciu, P., Pelegrini-Issac, M., Poline, J.-B., 2003. Robust Estimation of the Hemodynamic Response Function in Event-Related BOLD fMRI Using Basic Physiological Information. Hum. Brain Mapp. 19, 1-17., Marrelec, G., Benali, H., Ciuciu, P., Poline, J.B. Bayesian estimation of the hemodynamic of the hemodynamic response function in functional MRI. In: R. F, editor; 2001; Melville. p 229-247.] and its deterministic counterpart based on a combination of Tikhonov regularization [Tikhonov, A.N., Arsenin, V.Y., 1977. Solution of ill-posed problems. Washington DC: W.H. Winston.] and generalized cross-validation (GCV) [Wahba, G., 1990. Spline Models for Observational Data

  3. Trait impulsivity and impaired prefrontal impulse inhibition function in adolescents with internet gaming addiction revealed by a Go/No-Go fMRI study.

    Science.gov (United States)

    Ding, Wei-na; Sun, Jin-hua; Sun, Ya-Wen; Chen, Xue; Zhou, Yan; Zhuang, Zhi-guo; Li, Lei; Zhang, Yong; Xu, Jian-rong; Du, Ya-song

    2014-05-30

    Recent studies suggest that Internet gaming addiction (IGA) is an impulse disorder, or is at least related to impulse control disorders. In the present study, we hypothesized that different facets of trait impulsivity may be specifically linked to the brain regions with impaired impulse inhibition function in IGA adolescents. Seventeen adolescents with IGA and seventeen healthy controls were scanned during performance of a response-inhibition Go/No-Go task using a 3.0 T MRI scanner. The Barratt Impulsiveness Scale (BIS)-11 was used to assess impulsivity. There were no differences in the behavioral performance on the Go/No-Go task between the groups. However, the IGA group was significantly hyperactive during No-Go trials in the left superior medial frontal gyrus, right anterior cingulate cortex, right superior/middle frontal gyrus, left inferior parietal lobule, left precentral gyrus, and left precuneus and cuneus. Further, the bilateral middle temporal gyrus, bilateral inferior temporal gyrus, and right superior parietal lobule were significantly hypoactive during No-Go trials. Activation of the left superior medial frontal gyrus was positively associated with BIS-11 and Chen Internet Addiction Scale (CIAS) total score across IGA participants. Our data suggest that the prefrontal cortex may be involved in the circuit modulating impulsivity, while its impaired function may relate to high impulsivity in adolescents with IGA, which may contribute directly to the Internet addiction process.

  4. Millennial scale system impulse response of polar climates - deconvolution results between δ 18O records from Greenland and Antarctica

    Science.gov (United States)

    Reischmann, E.; Yang, X.; Rial, J. A.

    2013-12-01

    Deconvolution has long been used in science to recover real input given a system's impulse response and output. In this study, we applied spectral division deconvolution to select, polar, δ 18O time series to investigate the possible relationship between the climates of the Polar Regions, i.e. the equivalent to a climate system's ';impulse response.' While the records may be the result of nonlinear processes, deconvolution remains an appropriate tool because the two polar climates are synchronized, forming a Hilbert transform pair. In order to compare records, the age models of three Greenland and four Antarctica records have been matched via a Monte Carlo method using the methane-matched pair GRIP and BYRD as a basis for the calculations. For all twelve polar pairs, various deconvolution schemes (Wiener, Damped Least Squares, Tikhonov, Kalman filter) give consistent, quasi-periodic, impulse responses of the system. Multitaper analysis reveals strong, millennia scale, quasi-periodic oscillations in these system responses with a range of 2,500 to 1,000 years. These are not symmetric, as the transfer function from north to south differs from that of south to north. However, the difference is systematic and occurs in the predominant period of the deconvolved signals. Specifically, the north to south transfer function is generally of longer period than the south to north transfer function. High amplitude power peaks at 5.0ky to 1.7ky characterize the former, while the latter contains peaks at mostly short periods, with a range of 2.5ky to 1.0ky. Consistent with many observations, the deconvolved, quasi-periodic, transfer functions share the predominant periodicities found in the data, some of which are likely related to solar forcing (2.5-1.0ky), while some are probably indicative of the internal oscillations of the climate system (1.6-1.4ky). The approximately 1.5 ky transfer function may represent the internal periodicity of the system, perhaps even related to the

  5. The Use of Hydrograph Analysis and Impulse Response Functions to Improve Understanding of Groundwater Flooding: A Case Study from the Chalk Aquifer, United Kingdom.

    Science.gov (United States)

    Ascott, M.; Bloomfield, J.; Macdonald, D.; Marchant, B.; McKenzie, A.

    2017-12-01

    The Cretaceous Chalk, the most important aquifer in the United Kingdom (UK) for public water supply, underlies many large cities in southern and eastern England including parts of London, however, it is prone to groundwater flooding. We have developed a new approach to analyse the spatio-temporal extent of groundwater flooding using statistical analysis of groundwater level hydrographs and impulse response functions (IRFs) applied to a major Chalk groundwater flooding event in the UK during winter 2013/14. Using monthly groundwater levels for 26 boreholes in the Chalk and a new standardised index for groundwater flooding, we have: estimated standardised series; grouped them using k-means cluster analysis; and, cross-correlated the cluster centroids with the Standardised Precipitation Index accumulated over time intervals between 1 and 60 months. This analysis reveals two spatially coherent groups of standardised hydrographs which respond to precipitation over different timescales. We estimate IRF models of the groundwater level response to effective precipitation for three boreholes in each group. The IRF models support the SPI analysis showing different response functions between the two groups. If we apply identical effective precipitation inputs to each of the IRF models we see differences between the hydrographs from each group. It is proposed that these differences are due to the intrinsic, hydrogeological properties of the Chalk and of overlying relatively low permeability superficial deposits. Consequently, it is concluded that the overarching controls on groundwater flood response are a complex combination of antecedent conditions, rainfall and catchment hydrogeological properties. These controls should be taken into consideration when anticipating and managing future groundwater flood events.

  6. Solution of an inverse thermal problem by an analytical and impulse response method. Application to the determination of parietal temperature fluctuations inside a pipe

    International Nuclear Information System (INIS)

    Morilhat, P.; Maye, J.-P.; Brendle, E.; Hay, B.

    1992-01-01

    The solution of an inverse heat conduction problem (estimation of parietal temperature fluctuations inside a pipe from external measurements) using transfer functions is proposed. An analytical method and impulse response technique are studied, compared and tested for a pressurized water reactor (PWR) pipe, in working conditions favourable to thermal striping. The study shows the advantages of thermal stress measurements in comparison with temperature measurements for greater efficiency in the inverse method and gives proof of the greater suitability of the impulse response technique for complex geometries. (author)

  7. Video head-impulse test (vHIT) in dizzy children with normal caloric responses.

    Science.gov (United States)

    Khater, Ahmed Mohammed; Afifi, Pretty O

    2016-08-01

    The caloric test and the video head-impulse test are diagnostic tools to examine dizzy patients through assessing the function of the semicircular canals. There are major differences between the two tests as regards stimulus characteristics, methodology, and function examined. The aim of this study is to evaluate the results of vHIT in children and adolescents with normal caloric test. This work was performed on 63 patients, but 14 were excluded because of technical problems in the caloric test. So, this is a prospective work in 49 patients (27 females and 22 males) with different types of vestibular disease seen because of vertigo in which both procedures were performed the same day. The caloric test was performed with air at two different temperatures in which both ears were irrigated alternately. Then, the video head-impulse test was carried out. Main outcome measures were the gain of vestibulo-ocular reflex, gain asymmetry, and refixation saccades in the vHIT. in all studied cases, caloric test was normal. The mean age of patients was 16 years. By vHIT, in 8 patients (16%) no abnormality was detected, while abnormal findings were found in 41 patients. Single canal affection was seen in 29 patients whereas 12 patients had combined canal affection. The right side was affected in 27 and left side in 22 patients. In single canal affection, isolated horizontal canals were affected in 4, anterior canals in 5 and posterior canals in 20 patients. While in combined canal affection, the affection is seen in the same ear. Moreover the most common pattern seen is affection of left anterior and left posterior canals. The caloric and vHIT is very important tests in diagnosis of dizzy patients. The information from both methods is redundant in some cases but complementary in most. vHIT is a "child friendly," relatively easy-to-use, and simple tool to evaluate each of the 6 semicircular canals. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  8. FPGA-based electrocardiography (ECG signal analysis system using least-square linear phase finite impulse response (FIR filter

    Directory of Open Access Journals (Sweden)

    Mohamed G. Egila

    2016-12-01

    Full Text Available This paper presents a proposed design for analyzing electrocardiography (ECG signals. This methodology employs highpass least-square linear phase Finite Impulse Response (FIR filtering technique to filter out the baseline wander noise embedded in the input ECG signal to the system. Discrete Wavelet Transform (DWT was utilized as a feature extraction methodology to extract the reduced feature set from the input ECG signal. The design uses back propagation neural network classifier to classify the input ECG signal. The system is implemented on Xilinx 3AN-XC3S700AN Field Programming Gate Array (FPGA board. A system simulation has been done. The design is compared with some other designs achieving total accuracy of 97.8%, and achieving reduction in utilizing resources on FPGA implementation.

  9. Filter design of eight order butterworth infinite impulse response for earthquake sign

    Science.gov (United States)

    Perdana, Yusuf Hadi; Marsono, Agus

    2017-07-01

    Filtering is an important procedure in modern seismology analysis to obtain the best quality result in advanced process. There are many programs of signal processing consisting of signal filtering features, for example Seismic Analysis Code (SAC). Unfortunately, the basic mathematical equations in signal processing are not explained in detail. This research has purposes to design a Butterworth filter and to examine the influence of increasing order on the arrival time, polarity, and first motion amplitude of seismic wave. Filter design was done by computing eight order lowpass analog transfer functions and transforming them into lowpass, highpass, and bandpass digital using bilinear transformation so we have recursive and causal filters. The designed filter was then validated by the result of SAC. Based on the research we have found that the method and algorithm of designed filter are consistent with SAC. Increasing filter order can clarify the phases of seismic wave positions. On the other hand, it can influence the phase delay and impulse attenuation of seismic waves. The implication of this effects are error on computation of earthquake parameter and source mechanism. Filter instability due to increasing order will quickly occur if the cutoff frequency range is short or the sampling frequency is high. An appropriate passband frequency at low filter order can optimally generate earthquake filtered waves.

  10. Asymmetric Price Transmission in Food Supply Chains: Impulse Response Analysis by Local Projections Applied to U.S. Broiler and Pork Prices

    NARCIS (Netherlands)

    Kuiper, W.E.; Oude Lansink, A.G.J.M.

    2013-01-01

    In this article, the author's set out Jordà's (2005) method of local projections by which nonlinear/ asymmetric impulse responses can be computed without the need to specify and estimate the underlying nonlinear/asymmetric dynamic system. The method is used to compute price-reaction functions that

  11. Generalized synchronization via impulsive control

    International Nuclear Information System (INIS)

    Zhang Rong; Xu Zhenyuan; Yang, Simon X.; He Xueming

    2008-01-01

    This paper demonstrates theoretically that two completely different systems can implement GS via impulsive control, moreover by using impulsive control, for a given manifold y = H(x) we construct a response system to achieve GS with drive system and the synchronization manifold is y = H(x). Our theoretical results are supported by numerical examples

  12. A Methodology for Rapid Prototyping Peak-Constrained Least-Squares Bit-Serial Finite Impulse Response Filters in FPGAs

    Directory of Open Access Journals (Sweden)

    Alex Carreira

    2003-05-01

    Full Text Available Area-efficient peak-constrained least-squares (PCLS bit-serial finite impulse response (FIR filter implementations can be rapidly prototyped in field programmable gate arrays (FPGA with the methodology presented in this paper. Faster generation of the FPGA configuration bitstream is possible with a new application-specific mapping and placement method that uses JBits to avoid conventional general-purpose mapping and placement tools. JBits is a set of Java classes that provide an interface into the Xilinx Virtex FPGA configuration bitstream, allowing the user to generate new configuration bitstreams. PCLS coefficient generation allows passband-to-stopband energy ratio (PSR performance to be traded for a reduction in the filter's hardware cost without altering the minimum stopband attenuation. Fixed-point coefficients that meet the frequency response and hardware cost specifications can be generated with the PCLS method. It is not possible to meet these specifications solely by the quantization of floating-point coefficients generated in other methods.

  13. In-plane impulse response of a curved bar with varying cross-section

    International Nuclear Information System (INIS)

    Suzuki, Katsuyoshi; Kosawada, Tadashi; Takahashi, Shin; Miyashita, Yasushi.

    1984-01-01

    The vibration problem of a curved bar, of which the center line is represented with a plane curve, is important for the aseismatic design of the piping system and structures in chemical and nuclear plants. The dynamic response problem of an in-plane curved bar has not been sufficiently examined. In this study, the in-plane impact response of an in-plane curved bar having varying cross section when impact load acts in the direction of the center of curvature was analyzed. First, the Lagrangian of a curved bar with varying cross section when general exciting distributed load acts in the direction of the center of curvature along the center line was determined by the classic theory, and from its stationary condition, the equations of motion and boundary conditions were derived. Next, the equations of motion were analyzed by eigen-function development method. In the example of numerical calculation, the variation of displacement and bending moment in course of time when stepwise concentrated impact load acts on a both ends fixed symmetric semi-elliptic arc bar was determined. Besides, the change of response due to the change of cross section and the change of the point of impact load application was clarified. Displacement and bending moment varied at a certain period with static value at the center. (Kako, I.)

  14. A sum-over-paths impulse-response moment-extraction algorithm for RLCM IC-interconnect networks

    Science.gov (United States)

    Le Coz, Y. L.; Krishna, D.; Petranovic, D. M.

    2007-08-01

    We have created a new impulse-response (IR) moment-extraction algorithm for RLCM circuit networks. It employs a Feynman sum-over-paths postulate. Our approach begins with generation of s-domain nodal-voltage equations. We then perform a Taylor-series expansion of the circuit transfer function. These expansions yield transition diagrams involving mathematical coupling constants, or weight factors, in integral powers of complex frequency s. Our sum-over-paths postulate supports stochastic evaluation of path sums within the circuit transition diagram to any desired order of s. The specific order of s in the sum corresponds, as well, to the order of IR moment we seek to extract. In developing the algorithm, importantly, we maintain computational efficiency and full parallelism. Initial verification studies of uncoupled and coupled RLCM lines furnished promising results: less than 10% 1- σ error for m1 or m2 moment, after 10 K sampled path-sum terms. In addition, we observed excellent convergence to exact, analytical moment values with increasing number of samples. Our sum-over-paths postulate, in fact, implies generality for arbitrary RLCM-interconnect network topologies, beyond those specific examples presented in this work. We believe, in conclusion, that this type of IR-moment extraction algorithm may find useful application in a massively coupled electrical system, such as a high-end digital-IC interconnect network.

  15. A sum-over-paths impulse-response moment-extraction algorithm for RLC IC-interconnect networks

    Science.gov (United States)

    Le Coz, Y. L.; Krishna, D.; Hariharan, G.; Petranovic, D. M.

    2005-10-01

    We have created a new impulse-response (IR) moment-extraction algorithm for RLC circuit networks. It employs a Feynman sum-over-paths postulate. Our approach begins with generation of s-domain nodal-voltage equations. We then perform a Taylor-series expansion of the circuit transfer function. These expansions yield transition diagrams involving mathematical coupling constants, or weight factors, in integral powers of complex frequency s. Our sum-over-paths postulate supports stochastic evaluation of path sums within the circuit transition diagram to any desired order of s. The specific order of s in the sum corresponds, as well, to the order of IR moment we seek to extract. In developing the algorithm, importantly, we maintain computational efficiency and full parallelism. Initial verification studies of uncoupled and coupled RLC lines furnished promising results: 5% and 10% approximate 1- σ error for first- and second-order IR moments, respectively, after only 100 sampled path-sum terms. In addition, we observed excellent convergence to exact, analytical moment values with increasing number of samples. Our sum-over-paths postulate, in fact, implies generality for arbitrary RLC-interconnect networks, beyond those specific examples presented in this work. We believe, in conclusion, that this type of IR-moment extraction algorithm may find useful application in a massively coupled electrical system, such as that encountered in high-end digital-IC interconnects.

  16. A sum-over-paths impulse-response moment-extraction algorithm for RC IC-interconnect networks

    Science.gov (United States)

    Le Coz, Y. L.; Krishna, D.; Petranovic, D. M.; Loh, W. M.; Bendix, P.

    2004-12-01

    We have created a new impulse-response (IR) moment-extraction algorithm for RC circuit networks. It employs a Feynman sum-over-paths postulate. Our approach begins with generation of s-domain nodal-voltage equations. We then perform a Taylor-series expansion of the circuit transfer function. These expansions yield transition diagrams involving mathematical coupling constants, or weight factors, in integral powers of complex frequency s. Our sum-over-paths postulate supports stochastic evaluation of path sums within the circuit transition diagram to any desired order of s. The specific order of s in the sum corresponds, as well, to the order of IR moment we seek to extract. In developing the algorithm, importantly, we maintain computational efficiency and full parallelism. Initial verification studies of uncoupled and coupled RC lines furnished promising results: 5% and 15% approximate 1-σ error for first- and second-order IR moments, respectively, after only 100 sampled path-sum terms. In addition, we observed excellent convergence to exact, analytical moment values with increasing number of samples. Our sum-over-paths postulate, in fact, implies generality for arbitrary RC-interconnect networks, beyond those specific examples presented in this work. We believe, in conclusion, that this type of IR moment-extraction algorithm may find useful application in a massively coupled electrical system, such as that encountered in high-end digital-IC interconnects.

  17. Validation of the calculation of the renal impulse response function. An analysis of errors and systematic biases

    International Nuclear Information System (INIS)

    Erbsman, F.; Ham, H.; Piepsz, A.; Struyven, J.

    1978-01-01

    The renal impulse response function (Renal IRF) is the time-activity curve measured over one kidney after injection of a radiopharmaceutical in the renal artery. If the tracer is injected intravenously it is possible to compute the renal IRF by deconvoluting the kidney curve by a blood curve. In previous work we demonstrated that the computed IRF is in good agreement with measurements made after injection in the renal artery. The goal of the present work is the analysis of the effect of sampling errors and the influence of extra-renal activity. The sampling error is only important for the first point of the plasma curve and yields an ill-conditioned function P -1 . The addition of 50 computed renal IRF's demonstrated that the three first points show a larger variability due to incomplete mixing of the tracer. These points should thus not be included in the smoothing process. Subtraction of non-renal activity does not modify appreciably the shape of the renal IRF. The mean transit time and the time to half value are almost independent of non-renal activity and seem to be the parameters of choice

  18. Hsp60 response in experimental and human temporal lobe epilepsy

    Science.gov (United States)

    Gammazza, Antonella Marino; Colangeli, Roberto; Orban, Gergely; Pierucci, Massimo; Di Gennaro, Giancarlo; Bello, Margherita Lo; D'Aniello, Alfredo; Bucchieri, Fabio; Pomara, Cristoforo; Valentino, Mario; Muscat, Richard; Benigno, Arcangelo; Zummo, Giovanni; de Macario, Everly Conway; Cappello, Francesco; Di Giovanni, Giuseppe; Macario, Alberto J. L.

    2015-01-01

    The mitochondrial chaperonin Hsp60 is a ubiquitous molecule with multiple roles, constitutively expressed and inducible by oxidative stress. In the brain, Hsp60 is widely distributed and has been implicated in neurological disorders, including epilepsy. A role for mitochondria and oxidative stress has been proposed in epileptogenesis of temporal lobe epilepsy (TLE). Here, we investigated the involvement of Hsp60 in TLE using animal and human samples. Hsp60 immunoreactivity in the hippocampus, measured by Western blotting and immunohistochemistry, was increased in a rat model of TLE. Hsp60 was also increased in the hippocampal dentate gyrus neurons somata and neuropil and hippocampus proper (CA3, CA1) of the epileptic rats. We also determined the circulating levels of Hsp60 in epileptic animals and TLE patients using ELISA. The epileptic rats showed circulating levels of Hsp60 higher than controls. Likewise, plasma post-seizure Hsp60 levels in patients were higher than before the seizure and those of controls. These results demonstrate that Hsp60 is increased in both animals and patients with TLE in affected tissues, and in plasma in response to epileptic seizures, and point to it as biomarker of hippocampal stress potentially useful for diagnosis and patient management. PMID:25801186

  19. Neuroanatomical and Neurochemical Basis of Impulsivity

    Directory of Open Access Journals (Sweden)

    Kemal Yazici

    2010-08-01

    Full Text Available The term ‘impulsivity’ encompasses a multitude of behaviours that are poorly conceived, premature, inappropriate, and that frequently result in unwanted or deleterious outcomes. Impulsivity manifests as impatience carelessness, risk-taking, sensation-seeking and pleasure-seeking, an underestimated sense of harm, and extroversion. Impulsivity is a core symptom of a broad spectrum of psychiatric disorders. Through focusing on different aspects of impulsive behavior, it has proved possible to devise a variety of behavioral paradigms to measure impulsivity in both human and non-human subjects. These can be broadly divided into two categories: those measuring impulsive action or motoric impulsivity, and those measuring impulsive choice or impulsive decision-making. Impulsive action can be broadly defined as the inability to withhold from making a response. Within the framework of behavioral neuroscience and cognitive psychology, impulse control has been described as an active inhibitory mechanism which modulates the internally or externally driven pre-potent desire for primary reinforcers such as food, sex or other highly desirable rewards. This inhibitory control mechanism may provide the substrate by which rapid conditioned responses and reflexes are transiently suppressed, so that slower cognitive mechanisms can guide behavior. This process is referred to as response inhibition. Two of the most common tests used to study inhibitory processes are the go/no-go and stop-signal reaction time tasks. Impulsivity is also evident in the making of impulsive decisions or choices as well as in impulsive actions. Here, there is no “pre-potent” response that is primed and then forcibly inhibited, but a decision-making processes. Impulsive decision making or impulsive choice is defined as initiating actions without adequately considering other possible choices or consequences. Impulsive choice is typically measured in the delay discounting paradigm. In

  20. Modeling the dynamics of the lead bismuth eutectic experimental accelerator driven system by an infinite impulse response locally recurrent neural network

    International Nuclear Information System (INIS)

    Zio, Enrico; Pedroni, Nicola; Broggi, Matteo; Golea, Lucia Roxana

    2009-01-01

    In this paper, an infinite impulse response locally recurrent neural network (IIR-LRNN) is employed for modelling the dynamics of the Lead Bismuth Eutectic eXperimental Accelerator Driven System (LBE-XADS). The network is trained by recursive back-propagation (RBP) and its ability in estimating transients is tested under various conditions. The results demonstrate the robustness of the locally recurrent scheme in the reconstruction of complex nonlinear dynamic relationships

  1. Temporal response methods for dynamic measurement of in-process inventory of dissolved nuclear materials

    International Nuclear Information System (INIS)

    Ziri, S.M.; Seefeldt, W.B.

    1977-08-01

    This analysis has demonstrated that a plant's temporal response to perturbation of feed isotope composition can be used to measure the in-process inventory, without suspending plant operations. The main advantages of the temporal response technique over the step-displacement method are (1) it (the temporal response method) obviates the need for large special feed batches, and (2) it obviates the requirement that all the in-process material have a uniform isotopic composition at the beginning of the measurement. The temporal response method holds promise for essentially continuous real-time determination of in-process SNM. However, the temporal response method requires the measurement of the isotopic composition of many samples, and it works best for a stationary random input time series of tracer perturbations. Both of these requirements appear amenable to satisfaction by practical equipment and procedures if the benefits are deemed sufficiently worthwhile

  2. The Neurobiology of Impulsive Aggression.

    Science.gov (United States)

    Blair, Robert J R

    2016-02-01

    This selective review provides a model of the neurobiology of impulsive aggression from a cognitive neuroscience perspective. It is argued that prototypical cases of impulsive aggression, those associated with anger, involve the recruitment of the acute threat response system structures; that is, the amygdala, hypothalamus, and periaqueductal gray. It is argued that whether the recruitment of these structures results in impulsive aggression or not reflects the functional roles of ventromedial frontal cortex and dorsomedial frontal and anterior insula cortex in response selection. It is also argued that impulsive aggression may occur because of impaired decision making. The aggression may not be accompanied by anger, but it will reflect disrupted evaluation of the rewards/benefits of the action.

  3. Apathy and impulsivity in frontotemporal lobar degeneration syndromes.

    Science.gov (United States)

    Lansdall, Claire J; Coyle-Gilchrist, Ian T S; Jones, P Simon; Vázquez Rodríguez, Patricia; Wilcox, Alicia; Wehmann, Eileen; Dick, Katrina M; Robbins, Trevor W; Rowe, James B

    2017-06-01

    alone. Measures of apathy and impulsivity frequently loaded onto the same components reflecting their overlapping relationship. However, measures from objective tasks, patient-rated questionnaires and carer-rated questionnaires loaded onto separate components and revealed distinct neurobiology. Corticospinal tracts correlated with patients' self-ratings. In contrast, carer ratings correlated with atrophy in established networks for goal-directed behaviour, social cognition, motor control and vegetative functions, including frontostriatal circuits, orbital and temporal polar cortex, and the brainstem. Components reflecting response inhibition deficits correlated with focal frontal cortical atrophy. The dimensional approach to complex behavioural changes arising from frontotemporal lobar degeneration provides new insights into apathy and impulsivity, and the need for a joint therapeutic strategy against them. The separation of objective tests from subjective questionnaires, and patient from carer ratings, has important implications for clinical trial design.awx101media15448041163001. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain.

  4. Spatial and temporal dynamics of land use pattern response to ...

    African Journals Online (AJOL)

    Urban settlements account for only two percent of the Earth's land surface. However, over half of the world's population resides in cities (United Nations, 2001). The quantitative evidences presented here showed that there were drastic changes in the temporal and spatial dynamics of land use/land cover. As an overall ...

  5. Buying impulses : a study on impulsive consumption

    OpenAIRE

    Herabadi, A.G.

    2003-01-01

    This dissertation's objectives were to validate impulse buying tendency as a genuinely distinctive construct related to impulse purchase behavior and attached to fundamental personality traits, and its relationships to a number of relevant factors. Studies reported were steps to a better understanding of the impulse buying phenomenon. In the first 2 studies (using Dutch and Indonesian samples), a reliable 20-item scale to measure impulse buying tendency was developed. The scale has 2 facets r...

  6. Optimal control of impulsive Volterra equations with variable impulse times

    OpenAIRE

    Belbas, S. A.; Schmidt, W. H.

    2008-01-01

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

  7. Be quick about it. Endogenous estradiol level, menstrual cycle phase and trait impulsiveness predict impulsive choice in the context of reward acquisition.

    Science.gov (United States)

    Diekhof, Esther K

    2015-08-01

    This article is part of a Special Issue "Estradiol and Cognition". Variations in the steroid hormone 17ß-estradiol (E2) may promote intra-individual differences in reward seeking behavior and temporal decision-making (Reimers et al., 2014; Front. Neurosci. 8: 401). Yet, in humans the exact role of E2 in impulsive choice still needs to be determined. The present study assessed the effect of a cycle-dependent rise in endogenous E2 on temporal response adaptation across the follicular phase (FP). For this purpose a reward acquisition paradigm was employed that is sensitive to hormone-induced changes in central dopamine (DA) level. The present data show that women acted more impulsively in the early as opposed to the late FP. Early follicular E2 further correlated with an increased capacity to speed up for reward maximization, while simultaneously the ability to wait for higher reward was compromised. This correlation was most pronounced in women with low trait impulsiveness. In contrast, E2 and optimized response speed failed to correlate in women with high trait impulsiveness and in the late FP, despite a generally higher E2 level. Collectively, these findings support the theory that E2 may act as an endogenous DA agonist. The fact that the hormone-behavior relationship was restricted to women with low trait impulsiveness and thus supposedly lower central DA level provides indirect support for this idea. Yet, choices became relatively less impulsive in the state of heightened E2 (i.e., in the late FP), suggesting that the relationship between E2 and impulsive choice may not be linear, but might resemble an inverted U-function. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Temporal response methods for dynamic measurement of in-process inventory of dissolved nuclear materials

    International Nuclear Information System (INIS)

    Zivi, S.M.; Seefeldt, W.B.

    1976-01-01

    This analysis demonstrated that a plant's temporal response to perturbations of feed isotope composition can be used to measure the in-process inventory, without suspending plant operations. The main advantage of the temporal response technique over the step-displacement method are (1) it obviates the need for large special feed batches and (2) it obviates the requirement that all the in-process material have a uniform isotopic composition at the beginning of the measurement. The temporal response method holds promise for essentially continuous real-time determination of in-process SNM. The main disadvantage or problem with the temporal response method is that it requires the measurement of the isotopic composition of a great many samples to moderately high accuracy. This requirement appears amenable to solution by a modest effort in instrument development

  9. Spatial and temporal fluctuations in bacteria, microfauna and mineral nitrogen in response to a nutrient impulse in soil

    NARCIS (Netherlands)

    Zelenev, V.V.

    2004-01-01

    Fluctuations of bacterial populations can be observed when frequent and sufficiently long series of samples are obtained for direct microscopic or plate counts of bacteria. Fluctuations in bacterial numbers are especially noticeable after some disturbance of soil such as substrate addition. However,

  10. Impaired decisional impulsivity in pathological videogamers.

    Directory of Open Access Journals (Sweden)

    Michael A Irvine

    Full Text Available 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.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.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.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.

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

    DEFF Research Database (Denmark)

    Jepsen, J. R.M.; Rydkjaer, J.; Fagerlund, B.

    2018-01-01

    Background: Schizophrenia and attention-deficit/hyperactivity disorder (ADHD) are developmental disorders with shared clinical characteristics such as cognitive impairments and impulsivity. Impulsivity is a core feature of ADHD and an important factor in aggression, violence, and substance use...

  12. Understanding consumer's responses to negative emotions related to crowding on satisfaction and impulse purchase in retail: the mediating role of coping

    Directory of Open Access Journals (Sweden)

    Marlette Cassia Oliveira Ferreira

    Full Text Available Abstract The perception of crowding, understood as an individual's response to crowds, can be observed in retail environments and influences positive and negative emotions. In this research we test the mediating effect of coping – rational strategies adopted to deal with negative emotions – in the relationship between negative emotions (resulting from crowding perception and consumer behavior (measured by impulse purchase and satisfaction. The findings related to coping explain to what extent there is a positive response to human density in the retail environment. For this, a theoretical model was developed which includes the relationships among perception of crowding, positive and negative emotions, and consumer behavior. The model enhances the understanding of the crowding phenomenon by including relationships mediated by an oppositional strategy (coping dimension between negative emotions and consumer behaviors. To test the theoretical model, a survey was conducted with 456 respondents and hypothesis tests using structural equation modeling. It was evidenced that crowding perception has more robust effects on negative emotions than positive emotions. It is emphasized that with the inclusion of opposition mediation, the weak direct relationship between negative emotions and behaviors, becomes a positive relationship between negative emotion and impulse purchase, and negative emotion and satisfaction. In addition to the theoretical contributions of the tested model, future research and managerial implications are proposed at the end of the article.

  13. Metabolic and transcriptomic response of the wine yeast Saccharomyces cerevisiae strain EC1118 after an oxygen impulse under carbon-sufficient, nitrogen-limited fermentative conditions.

    Science.gov (United States)

    Orellana, Marcelo; Aceituno, Felipe F; Slater, Alex W; Almonacid, Leonardo I; Melo, Francisco; Agosin, Eduardo

    2014-05-01

    During alcoholic fermentation, Saccharomyces cerevisiae is exposed to continuously changing environmental conditions, such as decreasing sugar and increasing ethanol concentrations. Oxygen, a critical nutrient to avoid stuck and sluggish fermentations, is only discretely available throughout the process after pump-over operation. In this work, we studied the physiological response of the wine yeast S. cerevisiae strain EC1118 to a sudden increase in dissolved oxygen, simulating pump-over operation. With this aim, an impulse of dissolved oxygen was added to carbon-sufficient, nitrogen-limited anaerobic continuous cultures. Results showed that genes related to mitochondrial respiration, ergosterol biosynthesis, and oxidative stress, among other metabolic pathways, were induced after the oxygen impulse. On the other hand, mannoprotein coding genes were repressed. The changes in the expression of these genes are coordinated responses that share common elements at the level of transcriptional regulation. Beneficial and detrimental effects of these physiological processes on wine quality highlight the dual role of oxygen in 'making or breaking wines'. These findings will facilitate the development of oxygen addition strategies to optimize yeast performance in industrial fermentations. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  14. Temporal response of positive and negative regulators in response to acute and chronic exercise training in mice.

    Science.gov (United States)

    Olenich, Sara A; Gutierrez-Reed, Navarre; Audet, Gerald N; Olfert, I Mark

    2013-10-15

    Angiogenesis is controlled by a balance between positive and negative angiogenic factors, but temporal protein expression of many key angiogenic regulators in response to exercise are still poorly defined. In C57BL/6 mice, we evaluated the temporal protein expression of several pro-angiogenic and anti-angiogenic factors in response to (1) a single acute bout of exercise and (2) chronic exercise training resulting from 3, 5, 7, 14 and 28 days of voluntary wheel running. Following acute exercise, protein levels of vascular endothelial growth factor-A (VEGF), endostatin and nucleolin were increased at 2-4 h (P responsiveness of VEGF to exercise in untrained mice (i.e. 161% increase, P angiogenesis is controlled by a balance between positive and negative mitogens, and reveals a complex, highly-coordinated, temporal scheme whereby these factors can differentially influence capillary growth in response to acute versus chronic exercise.

  15. Determination of Flaw Size and Depth From Temporal Evolution of Thermal Response

    Science.gov (United States)

    Winfree, William P.; Zalameda, Joseph N.; Cramer, Elliott; Howell, Patricia A.

    2015-01-01

    Simple methods for reducing the pulsed thermographic responses of flaws have tended to be based on either the spatial or temporal response. This independent assessment limits the accuracy of characterization. A variational approach is presented for reducing the thermographic data to produce an estimated size for a flaw that incorporates both the temporal and spatial response to improve the characterization. The size and depth are determined from both the temporal and spatial thermal response of the exterior surface above a flaw and constraints on the length of the contour surrounding the delamination. Examples of the application of the technique to simulation and experimental data acquired are presented to investigate the limitations of the technique.

  16. Buying Impulses: A Study on Impulsive Consumption

    NARCIS (Netherlands)

    Herabadi, A.G.

    2003-01-01

    This dissertation's objectives were to validate impulse buying tendency as a genuinely distinctive construct related to impulse purchase behavior and attached to fundamental personality traits, and its relationships to a number of relevant factors. Studies reported were steps to a better

  17. The loudness of decaying impulsive sounds

    Science.gov (United States)

    Namba, S.; Hashimoto, T.; Rice, C. G.

    1987-08-01

    In the case of short duration sounds it is well known that temporal loudness summation occurs within a certain time period (i.e., critical duration), and a trade-off relationship is established between the sound intensity and the duration of the sound. Therefore, for the estimation of the loudness of brief sounds such as impulsive noise the temporal loudness summation must be considered. This paper deals with artificial impulsive sounds with a relatively short rise time and a long decay, as usually observed for actual impulsive sounds, and whether the loudness of an impulsive sound is determined by the peak level of the sound or by the total energy of the sound including the decaying part. L AX in ISO 1996, which is the single event exposure level, is chosen as an energy index of the sound in this paper. It is probable, however, that the time varying pattern of the sound or auditory after effect has an effect on the loudness of impulsive sounds. Such effects, however, are not reflected either in L AX or in the peak level measurement. Accordingly additional experiments have been carried out to examine the temporal characteristics of the hearing mechanism in relation to the loudness of impulsive sounds. As a result, it seems that L AX is a good measure of the loudness of impulsive sounds which are not too short, but when the duration of the sound is less than 60 ms the contribution of the auditory after-effect on the loudness needs to be taken into consideration. No relation could be found between the peak level and the loudness of impulsive sounds.

  18. Event-related potentials in response to violations of content and temporal event knowledge.

    Science.gov (United States)

    Drummer, Janna; van der Meer, Elke; Schaadt, Gesa

    2016-01-08

    Scripts that store knowledge of everyday events are fundamentally important for managing daily routines. Content event knowledge (i.e., knowledge about which events belong to a script) and temporal event knowledge (i.e., knowledge about the chronological order of events in a script) constitute qualitatively different forms of knowledge. However, there is limited information about each distinct process and the time course involved in accessing content and temporal event knowledge. Therefore, we analyzed event-related potentials (ERPs) in response to either correctly presented event sequences or event sequences that contained a content or temporal error. We found an N400, which was followed by a posteriorly distributed P600 in response to content errors in event sequences. By contrast, we did not find an N400 but an anteriorly distributed P600 in response to temporal errors in event sequences. Thus, the N400 seems to be elicited as a response to a general mismatch between an event and the established event model. We assume that the expectancy violation of content event knowledge, as indicated by the N400, induces the collapse of the established event model, a process indicated by the posterior P600. The expectancy violation of temporal event knowledge is assumed to induce an attempt to reorganize the event model in working memory, a process indicated by the frontal P600. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Photoconductive Detectors with Fast Temporal Response for Laser Produced Plasma Experiments

    International Nuclear Information System (INIS)

    M. J. May; C. Halvorson; T. Perry; F. Weber; P. Young; C. Silbernagel

    2008-01-01

    Processes during laser plasma experiments typically have time scales that are less than 100 ps. The measurement of these processes requires X-ray detectors with fast temporal resolution. We have measured the temporal responses and linearity of several different X-ray sensitive Photoconductive Detectors (PCDs). The active elements of the detectors investigated include both diamond (natural and synthetic) and GaAs crystals. The typical time responses of the GaAs PCDs are approximately 60 ps, respectively. Some characterizations using X-ray light from a synchrotron light source are presented

  20. Campground marketing - the impulse camper

    Science.gov (United States)

    Wilbur F. LaPage; Dale P. Ragain

    1972-01-01

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

  1. Temporal variability of foliar nutrients: responses to nitrogen deposition and prescribed fire in a temperate steppe

    Science.gov (United States)

    Lü, Xiao-Tao; Reed, Sasha C.; Hou, Shuang-Li; Hu, Yan-Yu; Wei, Hai-Wei; Lü, Fu-Mei; Cui, Qiang; Han, Xing Guo

    2017-01-01

    Plant nutrient concentrations and stoichiometry drive fundamental ecosystem processes, with important implications for primary production, diversity, and ecosystem sustainability. While a range of evidence exists regarding how plant nutrients vary across spatial scales, our understanding of their temporal variation remains less well understood. Nevertheless, we know nutrients regulate plant function across time, and that important temporal controls could strongly interact with environmental change. Here, we report results from a 3-year assessment of inter-annual changes of foliar nitrogen (N) and phosphorus (P) concentrations and stoichiometry in three dominant grasses in response to N deposition and prescribed fire in a temperate steppe of northern China. Foliar N and P concentrations and their ratios varied greatly among years, with this temporal variation strongly related to inter-annual variation in precipitation. Nitrogen deposition significantly increased foliar N concentrations and N:P ratios in all species, while fire significantly altered foliar N and P concentrations but had no significant impacts on N:P ratios. Generally, N addition enhanced the temporal stability of foliar N and decreased that of foliar P and of N:P ratios. Our results indicate that plant nutrient status and response to environmental change are temporally dynamic and that there are differential effects on the interactions between environmental change drivers and timing for different nutrients. These responses have important implications for consideration of global change effects on plant community structure and function, management strategies, and the modeling of biogeochemical cycles under global change scenarios.

  2. Virtual photon impulse of bunch, beampipe response, coherent RF Beamstrahlung; and BEPC bunch length, BES jam, virtual acceleration

    International Nuclear Information System (INIS)

    Jing Shen

    1993-01-01

    A brief EEE view of signal QED is presented. The research has been concentrated on the virtual photon modes of ultra relativistic shock wave in a bunch-beampipe system, and real photon modes of Coherent RF Beamstrahlung CRFB. Physically, the virtual photons emitted by a bunch were treated as a travelling pseudo wave packet in a flight coaxial cavity constructed by bunch-wakefield core and beampipe. Mathematically, it is a boundary solution of shock wave excited by ultra relativistic impulse of bunch. The new modes of solution: VTA, VTEM, VTM, VLE are virtual photon packets and RTE, RTM, RTEM are real photon modes of CRFB. By these results the author measured and corrected BEPC bunch length from signals of : (1) TOF reference of BES, (2) BPM of BEPC, (3) Colliding CRFB of BEPC - BES coupling signal, as well as (4) the ordinary method of Synchrotron Radiation. All results of the measured bunch lengths are in accordance with the design length of BEPC, and were verified by the BES data of vertex reconstruction of hadron events. The author also found that CRFB is the unknown jam source of BES electronics. VLE virtual photons can accelerate particles

  3. Impulsivity and Cluster B Personality Disorders.

    Science.gov (United States)

    Turner, Daniel; Sebastian, Alexandra; Tüscher, Oliver

    2017-03-01

    Impulsivity is a multifaceted construct and an important personality trait in various mental health conditions. Among personality disorders (PDs), especially cluster B PDs are affected. The aims of this review are to summarize the relevant findings of the past 3 years concerning impulsivity in cluster B PDs and to identify those subcomponents of self-reported impulsivity and experimentally measured impulse control that are most affected in these disorders. All studies referred to antisocial (ASPD) or borderline PD (BPD), and none were found for narcissistic or histrionic PD. In ASPD as well as BPD, self-report scales primarily revealed heightened impulsivity compared to healthy controls. In experimental tasks, ASPD patients showed impairments in response inhibition, while fewer deficits were found in delay discounting. BPD patients showed specific impairments in delay discounting and proactive interference, while response inhibition was less affected. However, after inducing high levels of stress, deficits in response inhibition could also be observed in BPD patients. Furthermore, negative affect led to altered brain activation patterns in BPD patients during impulse control tasks, but no behavioral impairments were found. As proposed by the DSM-5 alternative model for personality disorders, heightened impulsivity is a core personality trait in BPD and ASPD, which is in line with current research findings. However, different components of experimentally measured impulse control are affected in BPD and ASPD, and impulsivity occurring in negative emotional states or increased distress seems to be specific for BPD. Future research could be focused on measures that assess impulsive behaviors on a momentary basis as this is a promising approach especially for further ecological validation and transfer into clinical practice.

  4. Multipoint observation of the response of the magnetosphere and ionosphere related to the sudden impulse event on 19 November 2007

    Directory of Open Access Journals (Sweden)

    Segarra Antoni

    2015-01-01

    Full Text Available The aim of this study is to provide a complete scope of a magnetic sudden impulse (SI event along its way through interplanetary space and the magnetosphere until its arrival to the ground. In our case, we chose the event of 19th November 2007 because of the availability of enough well-located spacecraft at that moment for our purpose. We have used a 16 spacecraft data set. We calculated the mass flux variation and the change in magnetic field components across the discontinuity. Thus, we identified the solar wind discontinuity as a shock. We also calculated the orientation of the solar wind shock front. Then, we examined the effects of the shock front propagation in detail. With this large data set, we obtained a global view of the travelling wave front and identified the effects of the compressional wave front. Thus, we determined in detail the shock front passing through the different parts of the magnetosphere. We described the compressional effects in the bow shock, the magnetosheath, and the magnetopause and we depicted the propagation inside the inner magnetosphere. Moreover, we used an extensive data set from magnetic observatories on the ground and so we studied the global distribution of the SI waveform. Finally, the comparison of the observational facts with those derived from the theoretical model showed a good consistency. On the basis of the waveforms and polarizations of this SI, we determined the location in latitude where ionospheric currents (ICs changed their sense. And also, we related polarization at ground to polarization measured by GOES spacecraft.

  5. Method of the response adjustment to the impulse of an autoregressive model for stability analysis; Metodo de ajuste de la respuesta al impulso de un modelo autorregresivo para analisis de estabilidad

    Energy Technology Data Exchange (ETDEWEB)

    Castillo D, R.; Ortiz V, J.; Ruiz E, J.A. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)

    2008-07-01

    The method of the response to the impulse of an autoregressive model for stability analysis of the nuclear boiling water reactors had one of the best behaviors in a range of stable operation conditions to quasi stables during the benchmark of stability of the Forsmark reactors. The method was developed in Mat lab and it uses the Gauss-Newton optimization method for to carry out the adjustment from the response to the impulse. In this work a program in Fortran of the response method to the impulse of an autoregressive model it was developed, which uses an adaptive optimization algorithm called NL2SOL, instead of the original method. This change is due that Gauss-Newton method doesn't converge in some cases to the best adjustment parameters for what the method has been substituted in the more recent Mat lab versions. Among the main obtained results it has that the programmed autoregressive model converges to a smaller order that the original method and while less stable is the reactor it is more big the difference in the order. Also was found an important difference in the first adjustment parameter being caused by the response magnitude to the impulse. As to for the decay ratio and oscillation frequency both programs presented acceptable results. (Author)

  6. Temporal Prediction Errors Affect Short-Term Memory Scanning Response Time.

    Science.gov (United States)

    Limongi, Roberto; Silva, Angélica M

    2016-11-01

    The Sternberg short-term memory scanning task has been used to unveil cognitive operations involved in time perception. Participants produce time intervals during the task, and the researcher explores how task performance affects interval production - where time estimation error is the dependent variable of interest. The perspective of predictive behavior regards time estimation error as a temporal prediction error (PE), an independent variable that controls cognition, behavior, and learning. Based on this perspective, we investigated whether temporal PEs affect short-term memory scanning. Participants performed temporal predictions while they maintained information in memory. Model inference revealed that PEs affected memory scanning response time independently of the memory-set size effect. We discuss the results within the context of formal and mechanistic models of short-term memory scanning and predictive coding, a Bayes-based theory of brain function. We state the hypothesis that our finding could be associated with weak frontostriatal connections and weak striatal activity.

  7. Temporal dynamics of bacterioplankton communities in response to excessive nitrate loading in oligotrophic coastal water.

    Science.gov (United States)

    Dong, Zhiying; Wang, Kai; Chen, Xinxin; Zhu, Jianlin; Hu, Changju; Zhang, Demin

    2017-01-30

    Coastal ecosystems are receiving elevated loads of nitrogen (N) from anthropogenic sources. Understanding how excessive N loading affects bacterioplankton communities is critical to predict the biodiversity of marine ecosystems under conditions of eutrophic disturbance. In this study, oligotrophic coastal water microcosms were perturbed with nitrate in two loading modes: 1) one-off loading at the beginning of the incubation period; and 2) periodic loading every two days for 16days. Turnover in the bacterioplankton community was investigated by 16S rDNA gene amplicon sequencing. The alpha diversity of the bacterioplankton community showed great temporal variability and similar responses to the different treatments. Bacterioplankton community composition was influenced remarkably by time and N loading mode. The effects of N loading on bacterioplankton community structure showed obvious temporal variation, probably because of the great temporal variation in environmental parameters. This study provides insights into the effects of N pollution in anthropogenically perturbed marine environments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Amygdala temporal dynamics: temperamental differences in the timing of amygdala response to familiar and novel faces

    Directory of Open Access Journals (Sweden)

    Shelton Richard C

    2009-12-01

    Full Text Available Abstract Background Inhibited temperament - the predisposition to respond to new people, places or things with wariness or avoidance behaviors - is associated with increased risk for social anxiety disorder and major depression. Although the magnitude of the amygdala's response to novelty has been identified as a neural substrate of inhibited temperament, there may also be differences in temporal dynamics (latency, duration, and peak. We hypothesized that persons with inhibited temperament would have faster responses to novel relative to familiar neutral faces compared to persons with uninhibited temperament. We used event-related functional magnetic resonance imaging to measure the temporal dynamics of the blood oxygen level dependent (BOLD response to both novel and familiar neutral faces in participants with inhibited or uninhibited temperament. Results Inhibited participants had faster amygdala responses to novel compared with familiar faces, and both longer and greater amygdala response to all faces. There were no differences in peak response. Conclusion Faster amygdala response to novelty may reflect a computational bias that leads to greater neophobic responses and represents a mechanism for the development of social anxiety.

  9. Disordered semantic representation in schizophrenic temporal cortex revealed by neuromagnetic response patterns

    Directory of Open Access Journals (Sweden)

    Silberman Yaron

    2006-05-01

    Full Text Available Abstract Background Loosening of associations and thought disruption are key features of schizophrenic psychopathology. Alterations in neural networks underlying this basic abnormality have not yet been sufficiently identified. Previously, we demonstrated that spatio-temporal clustering of magnetic brain responses to pictorial stimuli map categorical representations in temporal cortex. This result has opened the possibility to quantify associative strength within and across semantic categories in schizophrenic patients. We hypothesized that in contrast to controls, schizophrenic patients exhibit disordered representations of semantic categories. Methods The spatio-temporal clusters of brain magnetic activities elicited by object pictures related to super-ordinate (flowers, animals, furniture, clothes and base-level (e.g. tulip, rose, orchid, sunflower categories were analysed in the source space for the time epochs 170–210 and 210–450 ms following stimulus onset and were compared between 10 schizophrenic patients and 10 control subjects. Results Spatio-temporal correlations of responses elicited by base-level concepts and the difference of within vs. across super-ordinate categories were distinctly lower in patients than in controls. Additionally, in contrast to the well-defined categorical representation in control subjects, unsupervised clustering indicated poorly defined representation of semantic categories in patients. Within the patient group, distinctiveness of categorical representation in the temporal cortex was positively related to negative symptoms and tended to be inversely related to positive symptoms. Conclusion Schizophrenic patients show a less organized representation of semantic categories in clusters of magnetic brain responses than healthy adults. This atypical neural network architecture may be a correlate of loosening of associations, promoting positive symptoms.

  10. Cortical Auditory-Evoked Responses in Preterm Neonates: Revisited by Spectral and Temporal Analyses.

    Science.gov (United States)

    Kaminska, A; Delattre, V; Laschet, J; Dubois, J; Labidurie, M; Duval, A; Manresa, A; Magny, J-F; Hovhannisyan, S; Mokhtari, M; Ouss, L; Boissel, A; Hertz-Pannier, L; Sintsov, M; Minlebaev, M; Khazipov, R; Chiron, C

    2017-08-11

    Characteristic preterm EEG patterns of "Delta-brushes" (DBs) have been reported in the temporal cortex following auditory stimuli, but their spatio-temporal dynamics remains elusive. Using 32-electrode EEG recordings and co-registration of electrodes' position to 3D-MRI of age-matched neonates, we explored the cortical auditory-evoked responses (AERs) after 'click' stimuli in 30 healthy neonates aged 30-38 post-menstrual weeks (PMW). (1) We visually identified auditory-evoked DBs within AERs in all the babies between 30 and 33 PMW and a decreasing response rate afterwards. (2) The AERs showed an increase in EEG power from delta to gamma frequency bands over the middle and posterior temporal regions with higher values in quiet sleep and on the right. (3) Time-frequency and averaging analyses showed that the delta component of DBs, which negatively peaked around 550 and 750 ms over the middle and posterior temporal regions, respectively, was superimposed with fast (alpha-gamma) oscillations and corresponded to the late part of the cortical auditory-evoked potential (CAEP), a feature missed when using classical CAEP processing. As evoked DBs rate and AERs delta to alpha frequency power decreased until full term, auditory-evoked DBs are thus associated with the prenatal development of auditory processing and may suggest an early emerging hemispheric specialization. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

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

    Directory of Open Access Journals (Sweden)

    Constantine Saadeh

    2015-04-01

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

  12. Carbon dioxide and climate impulse response functions for the computation of greenhouse gas metrics: a multi-model analysis

    Directory of Open Access Journals (Sweden)

    F. Joos

    2013-03-01

    Full Text Available The responses of carbon dioxide (CO2 and other climate variables to an emission pulse of CO2 into the atmosphere are often used to compute the Global Warming Potential (GWP and Global Temperature change Potential (GTP, to characterize the response timescales of Earth System models, and to build reduced-form models. In this carbon cycle-climate model intercomparison project, which spans the full model hierarchy, we quantify responses to emission pulses of different magnitudes injected under different conditions. The CO2 response shows the known rapid decline in the first few decades followed by a millennium-scale tail. For a 100 Gt-C emission pulse added to a constant CO2 concentration of 389 ppm, 25 ± 9% is still found in the atmosphere after 1000 yr; the ocean has absorbed 59 ± 12% and the land the remainder (16 ± 14%. The response in global mean surface air temperature is an increase by 0.20 ± 0.12 °C within the first twenty years; thereafter and until year 1000, temperature decreases only slightly, whereas ocean heat content and sea level continue to rise. Our best estimate for the Absolute Global Warming Potential, given by the time-integrated response in CO2 at year 100 multiplied by its radiative efficiency, is 92.5 × 10−15 yr W m−2 per kg-CO2. This value very likely (5 to 95% confidence lies within the range of (68 to 117 × 10−15 yr W m−2 per kg-CO2. Estimates for time-integrated response in CO2 published in the IPCC First, Second, and Fourth Assessment and our multi-model best estimate all agree within 15% during the first 100 yr. The integrated CO2 response, normalized by the pulse size, is lower for pre-industrial conditions, compared to present day, and lower for smaller pulses than larger pulses. In contrast, the response in temperature, sea level and ocean heat content is less sensitive to these choices. Although, choices in pulse size, background concentration, and model lead to uncertainties, the most important and

  13. Continuous carryover of temporal context dissociates response bias from perceptual influence for duration.

    Directory of Open Access Journals (Sweden)

    Martin Wiener

    Full Text Available Recent experimental evidence suggests that the perception of temporal intervals is influenced by the temporal context in which they are presented. A longstanding example is the time-order-error, wherein the perception of two intervals relative to one another is influenced by the order in which they are presented. Here, we test whether the perception of temporal intervals in an absolute judgment task is influenced by the preceding temporal context. Human subjects participated in a temporal bisection task with no anchor durations (partition method. Intervals were demarcated by a Gaussian blob (visual condition or burst of white noise (auditory condition that persisted for one of seven logarithmically spaced sub-second intervals. Crucially, the order in which stimuli were presented was first-order counterbalanced, allowing us to measure the carryover effect of every successive combination of intervals. The results demonstrated a number of distinct findings. First, the perception of each interval was biased by the prior response, such that each interval was judged similarly to the preceding trial. Second, the perception of each interval was also influenced by the prior interval, such that perceived duration shifted away from the preceding interval. Additionally, the effect of decision bias was larger for visual intervals, whereas auditory intervals engendered greater perceptual carryover. We quantified these effects by designing a biologically-inspired computational model that measures noisy representations of time against an adaptive memory prior while simultaneously accounting for uncertainty, consistent with a Bayesian heuristic. We found that our model could account for all of the effects observed in human data. Additionally, our model could only accommodate both carryover effects when uncertainty and memory were calculated separately, suggesting separate neural representations for each. These findings demonstrate that time is susceptible to

  14. TargetingImpulsivity

    NARCIS (Netherlands)

    Bergh, Filip Sebastiaan van den

    2006-01-01

    Impulsivity, poorly conceived or prematurely executed behavior, is an important characteristic of human personality, but to some people, impulsivity is debilitating. They are unable to maintain jobs or friends. In this thesis, we study the differences and similarities of two different types of

  15. Modulation of Visual Responses in the Superior Temporal Sulcus by Audio-Visual Congruency

    OpenAIRE

    Dahl, Christoph D.; Logothetis, Nikos K.; Kayser, Christoph

    2010-01-01

    Our ability to identify or recognize visual objects is often enhanced by evidence provided by other sensory modalities. Yet, where and how visual object processing benefits from the information received by the other senses remains unclear. One candidate region is the temporal lobe, which features neural representations of visual objects, and in which previous studies have provided evidence for multisensory influences on neural responses. In the present study we directly tested whether visual ...

  16. Temporal characteristics of gustatory responses in rat parabrachial neurons vary by stimulus and chemosensitive neuron type.

    Science.gov (United States)

    Geran, Laura; Travers, Susan

    2013-01-01

    It has been demonstrated that temporal features of spike trains can increase the amount of information available for gustatory processing. However, the nature of these temporal characteristics and their relationship to different taste qualities and neuron types are not well-defined. The present study analyzed the time course of taste responses from parabrachial (PBN) neurons elicited by multiple applications of "sweet" (sucrose), "salty" (NaCl), "sour" (citric acid), and "bitter" (quinine and cycloheximide) stimuli in an acute preparation. Time course varied significantly by taste stimulus and best-stimulus classification. Across neurons, the ensemble code for the three electrolytes was similar initially but quinine diverged from NaCl and acid during the second 500 ms of stimulation and all four qualities became distinct just after 1s. This temporal evolution was reflected in significantly broader tuning during the initial response. Metric space analyses of quality discrimination by individual neurons showed that increases in information (H) afforded by temporal factors was usually explained by differences in rate envelope, which had a greater impact during the initial 2s (22.5% increase in H) compared to the later response (9.5%). Moreover, timing had a differential impact according to cell type, with between-quality discrimination in neurons activated maximally by NaCl or citric acid most affected. Timing was also found to dramatically improve within-quality discrimination (80% increase in H) in neurons that responded optimally to bitter stimuli (B-best). Spikes from B-best neurons were also more likely to occur in bursts. These findings suggest that among PBN taste neurons, time-dependent increases in mutual information can arise from stimulus- and neuron-specific differences in response envelope during the initial dynamic period. A stable rate code predominates in later epochs.

  17. High impulsivity predicting vulnerability to cocaine addiction in rats

    DEFF Research Database (Denmark)

    Molander, Anna C; Mar, Adam; Norbury, Agnes

    2011-01-01

    RATIONALE: Impulsivity is a vulnerability marker for drug addiction in which other behavioural traits such as anxiety and novelty seeking ('sensation seeking') are also widely present. However, inter-relationships between impulsivity, novelty seeking and anxiety traits are poorly understood...... increasing or decreasing impulsivity in SHI and SLI rats, did reduce the contrast in impulsivity between these two groups of animals. CONCLUSIONS: This investigation indicates that behavioural impulsivity in rats on the 5-CSRTT, which predicts vulnerability for cocaine addiction, is distinct from anxiety......, novelty reactivity and novelty-induced stress responses, and thus has relevance for the aetiology of drug addiction....

  18. Effects of deafness and cochlear implant use on temporal response characteristics in cat primary auditory cortex.

    Science.gov (United States)

    Fallon, James B; Shepherd, Robert K; Nayagam, David A X; Wise, Andrew K; Heffer, Leon F; Landry, Thomas G; Irvine, Dexter R F

    2014-09-01

    We have previously shown that neonatal deafness of 7-13 months duration leads to loss of cochleotopy in the primary auditory cortex (AI) that can be reversed by cochlear implant use. Here we describe the effects of a similar duration of deafness and cochlear implant use on temporal processing. Specifically, we compared the temporal resolution of neurons in AI of young adult normal-hearing cats that were acutely deafened and implanted immediately prior to recording with that in three groups of neonatally deafened cats. One group of neonatally deafened cats received no chronic stimulation. The other two groups received up to 8 months of either low- or high-rate (50 or 500 pulses per second per electrode, respectively) stimulation from a clinical cochlear implant, initiated at 10 weeks of age. Deafness of 7-13 months duration had no effect on the duration of post-onset response suppression, latency, latency jitter, or the stimulus repetition rate at which units responded maximally (best repetition rate), but resulted in a statistically significant reduction in the ability of units to respond to every stimulus in a train (maximum following rate). None of the temporal response characteristics of the low-rate group differed from those in acutely deafened controls. In contrast, high-rate stimulation had diverse effects: it resulted in decreased suppression duration, longer latency and greater jitter relative to all other groups, and an increase in best repetition rate and cut-off rate relative to acutely deafened controls. The minimal effects of moderate-duration deafness on temporal processing in the present study are in contrast to its previously-reported pronounced effects on cochleotopy. Much longer periods of deafness have been reported to result in significant changes in temporal processing, in accord with the fact that duration of deafness is a major factor influencing outcome in human cochlear implantees. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Dopa therapy and action impulsivity: subthreshold error activation and suppression in Parkinson's disease

    NARCIS (Netherlands)

    Fluchère, F.; Deveaux, M.; Burle, B.; Vidal, F.; van den Wildenberg, W.P.M.; Witjas, T.; Eusebio, A.; Azulay, J.-P.; Hasbroucq, T.

    2015-01-01

    Rationale: Impulsive actions entail (1) capture of the motor system by an action impulse, which is an urge to act and (2) failed suppression of that impulse in order to prevent a response error. Several studies indicate that dopaminergic treatment can induce action impulsivity in patients diagnosed

  20. Posterior superior temporal sulcus responses predict perceived pleasantness of skin stroking

    Directory of Open Access Journals (Sweden)

    Monika Davidovic

    2016-09-01

    Full Text Available Love and affection is expressed through a range of physically intimate gestures, including caresses. Recent studies suggest that posterior temporal lobe areas typically associated with visual processing of social cues also respond to interpersonal touch. Here, we asked whether these areas are selective to caress-like skin stroking. We collected functional magnetic resonance imaging (fMRI data from 23 healthy participants and compared brain responses to skin stroking and vibration. We did not find any significant differences between stroking and vibration in the posterior temporal lobe; however, right posterior superior temporal sulcus (pSTS responses predicted healthy participant's perceived pleasantness of skin stroking, but not vibration. These findings link right pSTS responses to individual variability in perceived pleasantness of caress-like tactile stimuli. We speculate that the right pSTS may play a role in the translation of tactile stimuli into positively valenced, socially relevant interpersonal touch and that this system may be affected in disorders associated with impaired attachment.

  1. Temporal thrombospondin-1 mRNA response in skeletal muscle exposed to acute and chronic exercise.

    Science.gov (United States)

    Olfert, I Mark; Breen, Ellen C; Gavin, Timothy P; Wagner, Peter D

    2006-12-01

    Thrombospondin-l (TSP-1) is believed to be an endogenous angiogenic inhibitor. In this study, we report that a single 1 h bout of treadmill running increases TSP-1 mRNA 3-4-fold (p response of TSP-1 mRNA to exercise was ablated after 3 days. Following long-term training (8 weeks, 1 h/day, 5 d/wk), in either normoxia or chronic hypoxia, the TSP-1 mRNA response to an acute bout of exercise was restored and increased 3-4-fold (p response to a single acute exercise bout, its temporal response to repetitive exercise bouts, and the putative role of TSP-1 in the angiogenic process, we speculate that TSP-1 may play a role in regulating the onset of skeletal muscle angiogenesis in response to exercise.

  2. Shock Tube as an Impulsive Application Device

    Directory of Open Access Journals (Sweden)

    Soumya Ranjan Nanda

    2017-01-01

    Full Text Available Current investigations solely focus on application of an impulse facility in diverse area of high-speed aerodynamics and structural mechanics. Shock tube, the fundamental impulse facility, is specially designed and calibrated for present objectives. Force measurement experiments are performed on a hemispherical test model integrated with the stress wave force balance. Similar test model is considered for heat transfer measurements using coaxial thermocouple. Force and heat transfer experiments demonstrated that the strain gauge and thermocouple have lag time of 11.5 and 9 microseconds, respectively. Response time of these sensors in measuring the peak load is also measured successfully using shock tube facility. As an outcome, these sensors are found to be suitable for impulse testing. Lastly, the response of aluminum plates subjected to impulsive loading is analyzed by measuring the in-plane strain produced during deformation. Thus, possibility of forming tests in shock is also confirmed.

  3. Non-inductive components of electromagnetic signals associated with L'Aquila earthquake sequences estimated by means of inter-station impulse response functions

    Directory of Open Access Journals (Sweden)

    C. Di Lorenzo

    2011-04-01

    Full Text Available On 6 April 2009 at 01:32:39 UT a strong earthquake occurred west of L'Aquila at the very shallow depth of 9 km. The main shock local magnitude was Ml = 5.8 (Mw = 6.3. Several powerful aftershocks occurred the following days. The epicentre of the main shock occurred 6 km away from the Geomagnetic Observatory of L'Aquila, on a fault 15 km long having a NW-SE strike, about 140°, and a SW dip of about 42°. For this reason, L'Aquila seismic events offered very favourable conditions to detect possible electromagnetic emissions related to the earthquake. The data used in this work come from the permanent geomagnetic Observatories of L'Aquila and Duronia. Here the results concerning the analysis of the residual magnetic field estimated by means of the inter-station impulse response functions in the frequency band from 0.3 Hz to 3 Hz are shown.

  4. Modulation of visual responses in the superior temporal sulcus by audio-visual congruency

    Directory of Open Access Journals (Sweden)

    Christoph Dahl

    2010-04-01

    Full Text Available Our ability to identify or recognize visual objects is often enhanced by evidence provided by other sensory modalities. Yet, where and how visual object processing benefits from the information received by the other senses remains unclear. One candidate region is the temporal lobe, which features neural representations of visual objects, and in which previous studies have provided evidence for multisensory influences on neural responses. In the present study we directly tested whether visual representations in the lower bank of the superior temporal sulcus (STS benefit from acoustic information. To this end, we recorded neural responses in alert monkeys passively watching audio-visual scenes, and quantified the impact of simultaneously presented sounds on responses elicited by the presentation of naturalistic visual scenes. Using methods of stimulus decoding and information theory, we then asked whether the responses of STS neurons become more reliable and informative in multisensory contexts. Our results demonstrate that STS neurons are indeed sensitive to the modality composition of the sensory stimulus. Importantly, information provided by STS neurons’ responses about the particular visual stimulus being presented was highest during congruent audio-visual and unimodal visual stimulation, but was reduced during incongruent bimodal stimulation. Together, these findings demonstrate that higher visual representations in the STS not only convey information about the visual input but also depend on the acoustic context of a visual scene.

  5. Modulation of visual responses in the superior temporal sulcus by audio-visual congruency.

    Science.gov (United States)

    Dahl, Christoph D; Logothetis, Nikos K; Kayser, Christoph

    2010-01-01

    Our ability to identify or recognize visual objects is often enhanced by evidence provided by other sensory modalities. Yet, where and how visual object processing benefits from the information received by the other senses remains unclear. One candidate region is the temporal lobe, which features neural representations of visual objects, and in which previous studies have provided evidence for multisensory influences on neural responses. In the present study we directly tested whether visual representations in the lower bank of the superior temporal sulcus (STS) benefit from acoustic information. To this end, we recorded neural responses in alert monkeys passively watching audio-visual scenes, and quantified the impact of simultaneously presented sounds on responses elicited by the presentation of naturalistic visual scenes. Using methods of stimulus decoding and information theory, we then asked whether the responses of STS neurons become more reliable and informative in multisensory contexts. Our results demonstrate that STS neurons are indeed sensitive to the modality composition of the sensory stimulus. Importantly, information provided by STS neurons' responses about the particular visual stimulus being presented was highest during congruent audio-visual and unimodal visual stimulation, but was reduced during incongruent bimodal stimulation. Together, these findings demonstrate that higher visual representations in the STS not only convey information about the visual input but also depend on the acoustic context of a visual scene.

  6. Echoic memory: investigation of its temporal resolution by auditory offset cortical responses.

    Science.gov (United States)

    Nishihara, Makoto; Inui, Koji; Morita, Tomoyo; Kodaira, Minori; Mochizuki, Hideki; Otsuru, Naofumi; Motomura, Eishi; Ushida, Takahiro; Kakigi, Ryusuke

    2014-01-01

    Previous studies showed that the amplitude and latency of the auditory offset cortical response depended on the history of the sound, which implicated the involvement of echoic memory in shaping a response. When a brief sound was repeated, the latency of the offset response depended precisely on the frequency of the repeat, indicating that the brain recognized the timing of the offset by using information on the repeat frequency stored in memory. In the present study, we investigated the temporal resolution of sensory storage by measuring auditory offset responses with magnetoencephalography (MEG). The offset of a train of clicks for 1 s elicited a clear magnetic response at approximately 60 ms (Off-P50m). The latency of Off-P50m depended on the inter-stimulus interval (ISI) of the click train, which was the longest at 40 ms (25 Hz) and became shorter with shorter ISIs (2.5∼20 ms). The correlation coefficient r2 for the peak latency and ISI was as high as 0.99, which suggested that sensory storage for the stimulation frequency accurately determined the Off-P50m latency. Statistical analysis revealed that the latency of all pairs, except for that between 200 and 400 Hz, was significantly different, indicating the very high temporal resolution of sensory storage at approximately 5 ms.

  7. Response errors explain the failure of independent-channels models of perception of temporal order

    Directory of Open Access Journals (Sweden)

    Miguel A García-Pérez

    2012-04-01

    Full Text Available Independent-channels models of perception of temporal order (also referred to as threshold models or perceptual latency models have been ruled out because two formal properties of these models (monotonicity and parallelism are not borne out by data from ternary tasks in which observers must judge whether stimulus A was presented before, after, or simultaneously with stimulus B. These models generally assume that observed responses are authentic indicators of unobservable judgments, but blinks, lapses of attention, or errors in pressing the response keys (maybe, but not only, motivated by time pressure when reaction times are being recorded may make observers misreport their judgments or simply guess a response. We present an extension of independent-channels models that considers response errors and we show that the model produces psychometric functions that do not satisfy monotonicity and parallelism. The model is illustrated by fitting it to data from a published study in which the ternary task was used. The fitted functions describe very accurately the absence of monotonicity and parallelism shown by the data. These characteristics of empirical data are thus consistent with independent-channels models when response errors are taken into consideration. The implications of these results for the analysis and interpretation of temporal-order judgment data are discussed.

  8. Response errors explain the failure of independent-channels models of perception of temporal order.

    Science.gov (United States)

    García-Pérez, Miguel A; Alcalá-Quintana, Rocío

    2012-01-01

    Independent-channels models of perception of temporal order (also referred to as threshold models or perceptual latency models) have been ruled out because two formal properties of these models (monotonicity and parallelism) are not borne out by data from ternary tasks in which observers must judge whether stimulus A was presented before, after, or simultaneously with stimulus B. These models generally assume that observed responses are authentic indicators of unobservable judgments, but blinks, lapses of attention, or errors in pressing the response keys (maybe, but not only, motivated by time pressure when reaction times are being recorded) may make observers misreport their judgments or simply guess a response. We present an extension of independent-channels models that considers response errors and we show that the model produces psychometric functions that do not satisfy monotonicity and parallelism. The model is illustrated by fitting it to data from a published study in which the ternary task was used. The fitted functions describe very accurately the absence of monotonicity and parallelism shown by the data. These characteristics of empirical data are thus consistent with independent-channels models when response errors are taken into consideration. The implications of these results for the analysis and interpretation of temporal order judgment data are discussed.

  9. Echoic memory: investigation of its temporal resolution by auditory offset cortical responses.

    Directory of Open Access Journals (Sweden)

    Makoto Nishihara

    Full Text Available Previous studies showed that the amplitude and latency of the auditory offset cortical response depended on the history of the sound, which implicated the involvement of echoic memory in shaping a response. When a brief sound was repeated, the latency of the offset response depended precisely on the frequency of the repeat, indicating that the brain recognized the timing of the offset by using information on the repeat frequency stored in memory. In the present study, we investigated the temporal resolution of sensory storage by measuring auditory offset responses with magnetoencephalography (MEG. The offset of a train of clicks for 1 s elicited a clear magnetic response at approximately 60 ms (Off-P50m. The latency of Off-P50m depended on the inter-stimulus interval (ISI of the click train, which was the longest at 40 ms (25 Hz and became shorter with shorter ISIs (2.5∼20 ms. The correlation coefficient r2 for the peak latency and ISI was as high as 0.99, which suggested that sensory storage for the stimulation frequency accurately determined the Off-P50m latency. Statistical analysis revealed that the latency of all pairs, except for that between 200 and 400 Hz, was significantly different, indicating the very high temporal resolution of sensory storage at approximately 5 ms.

  10. Echoic Memory: Investigation of Its Temporal Resolution by Auditory Offset Cortical Responses

    Science.gov (United States)

    Nishihara, Makoto; Inui, Koji; Morita, Tomoyo; Kodaira, Minori; Mochizuki, Hideki; Otsuru, Naofumi; Motomura, Eishi; Ushida, Takahiro; Kakigi, Ryusuke

    2014-01-01

    Previous studies showed that the amplitude and latency of the auditory offset cortical response depended on the history of the sound, which implicated the involvement of echoic memory in shaping a response. When a brief sound was repeated, the latency of the offset response depended precisely on the frequency of the repeat, indicating that the brain recognized the timing of the offset by using information on the repeat frequency stored in memory. In the present study, we investigated the temporal resolution of sensory storage by measuring auditory offset responses with magnetoencephalography (MEG). The offset of a train of clicks for 1 s elicited a clear magnetic response at approximately 60 ms (Off-P50m). The latency of Off-P50m depended on the inter-stimulus interval (ISI) of the click train, which was the longest at 40 ms (25 Hz) and became shorter with shorter ISIs (2.5∼20 ms). The correlation coefficient r2 for the peak latency and ISI was as high as 0.99, which suggested that sensory storage for the stimulation frequency accurately determined the Off-P50m latency. Statistical analysis revealed that the latency of all pairs, except for that between 200 and 400 Hz, was significantly different, indicating the very high temporal resolution of sensory storage at approximately 5 ms. PMID:25170608

  11. Effects of Temporal Framing on Response to Antismoking Messages: The Mediating Role of Perceived Relevance.

    Science.gov (United States)

    Zhao, Xiaoquan; Peterson, Emily

    2017-01-01

    This study tested the effect of temporal framing on young adult smokers' response to antismoking communication messages. In two studies using largely identical designs, young adult smokers recruited from a large university (n = 52) and Amazon Mechanical Turk (n = 210) were exposed to either no messages or messages featuring different temporal frames. Analysis of the combined data (N = 262) showed that framing the health consequences of smoking in a proximal (vs. distal) time frame led to greater perceived message relevance, less use of heuristic processing, greater use of systematic processing, greater positive affect, and more intense fear. Mediation analysis showed that perceived relevance was a significant mediator of the effect of temporal framing on message processing and emotional responses. In separate analysis of the Amazon Mechanical Turk data, the proximal frame also showed a consistent pattern of stronger impact on behavioral intentions compared to the distal frame, but the difference was only significant on the measure of intending to try to quit. Overall, findings of this study suggest that using proximal (vs. distal) frames may enhance receptivity to antismoking messages among young adult smokers, although the behavioral impact of this framing strategy still awaits further research.

  12. Long-Range Temporal Correlations Reflect Treatment Response in the Electroencephalogram of Patients with Infantile Spasms.

    Science.gov (United States)

    Smith, Rachel J; Sugijoto, Amanda; Rismanchi, Neggy; Hussain, Shaun A; Shrey, Daniel W; Lopour, Beth A

    2017-11-01

    Infantile spasms syndrome is an epileptic encephalopathy in which prompt diagnosis and treatment initiation are critical to therapeutic response. Diagnosis of the disease heavily depends on the identification of characteristic electroencephalographic (EEG) patterns, including hypsarrhythmia. However, visual assessment of the presence and characteristics of hypsarrhythmia is challenging because multiple variants of the pattern exist, leading to poor inter-rater reliability. We investigated whether a quantitative measurement of the control of neural synchrony in the EEGs of infantile spasms patients could be used to reliably distinguish the presence of hypsarrhythmia and indicate successful treatment outcomes. We used autocorrelation and Detrended Fluctuation Analysis (DFA) to measure the strength of long-range temporal correlations in 21 infantile spasms patients before and after treatment and 21 control subjects. The strength of long-range temporal correlations was significantly lower in patients with hypsarrhythmia than control patients, indicating decreased control of neural synchrony. There was no difference between patients without hypsarrhythmia and control patients. Further, the presence of hypsarrhythmia could be classified based on the DFA exponent and intercept with 92% accuracy using a support vector machine. Successful treatment was marked by a larger increase in the DFA exponent compared to those in which spasms persisted. These results suggest that the strength of long-range temporal correlations is a marker of pathological cortical activity that correlates with treatment response. Combined with current clinical measures, this quantitative tool has the potential to aid objective identification of hypsarrhythmia and assessment of treatment efficacy to inform clinical decision-making.

  13. Brain-responsive neurostimulation in patients with medically intractable mesial temporal lobe epilepsy.

    Science.gov (United States)

    Geller, Eric B; Skarpaas, Tara L; Gross, Robert E; Goodman, Robert R; Barkley, Gregory L; Bazil, Carl W; Berg, Michael J; Bergey, Gregory K; Cash, Sydney S; Cole, Andrew J; Duckrow, Robert B; Edwards, Jonathan C; Eisenschenk, Stephan; Fessler, James; Fountain, Nathan B; Goldman, Alicia M; Gwinn, Ryder P; Heck, Christianne; Herekar, Aamar; Hirsch, Lawrence J; Jobst, Barbara C; King-Stephens, David; Labar, Douglas R; Leiphart, James W; Marsh, W Richard; Meador, Kimford J; Mizrahi, Eli M; Murro, Anthony M; Nair, Dileep R; Noe, Katherine H; Park, Yong D; Rutecki, Paul A; Salanova, Vicenta; Sheth, Raj D; Shields, Donald C; Skidmore, Christopher; Smith, Michael C; Spencer, David C; Srinivasan, Shraddha; Tatum, William; Van Ness, Paul C; Vossler, David G; Wharen, Robert E; Worrell, Gregory A; Yoshor, Daniel; Zimmerman, Richard S; Cicora, Kathy; Sun, Felice T; Morrell, Martha J

    2017-06-01

    Evaluate the seizure-reduction response and safety of mesial temporal lobe (MTL) brain-responsive stimulation in adults with medically intractable partial-onset seizures of mesial temporal lobe origin. Subjects with mesial temporal lobe epilepsy (MTLE) were identified from prospective clinical trials of a brain-responsive neurostimulator (RNS System, NeuroPace). The seizure reduction over years 2-6 postimplantation was calculated by assessing the seizure frequency compared to a preimplantation baseline. Safety was assessed based on reported adverse events. There were 111 subjects with MTLE; 72% of subjects had bilateral MTL onsets and 28% had unilateral onsets. Subjects had one to four leads placed; only two leads could be connected to the device. Seventy-six subjects had depth leads only, 29 had both depth and strip leads, and 6 had only strip leads. The mean follow-up was 6.1 ± (standard deviation) 2.2 years. The median percent seizure reduction was 70% (last observation carried forward). Twenty-nine percent of subjects experienced at least one seizure-free period of 6 months or longer, and 15% experienced at least one seizure-free period of 1 year or longer. There was no difference in seizure reduction in subjects with and without mesial temporal sclerosis (MTS), bilateral MTL onsets, prior resection, prior intracranial monitoring, and prior vagus nerve stimulation. In addition, seizure reduction was not dependent on the location of depth leads relative to the hippocampus. The most frequent serious device-related adverse event was soft tissue implant-site infection (overall rate, including events categorized as device-related, uncertain, or not device-related: 0.03 per implant year, which is not greater than with other neurostimulation devices). Brain-responsive stimulation represents a safe and effective treatment option for patients with medically intractable epilepsy, including patients with unilateral or bilateral MTLE who are not candidates for

  14. Temporal dynamics of host molecular responses differentiate symptomatic and asymptomatic influenza a infection.

    Directory of Open Access Journals (Sweden)

    Yongsheng Huang

    2011-08-01

    Full Text Available Exposure to influenza viruses is necessary, but not sufficient, for healthy human hosts to develop symptomatic illness. The host response is an important determinant of disease progression. In order to delineate host molecular responses that differentiate symptomatic and asymptomatic Influenza A infection, we inoculated 17 healthy adults with live influenza (H3N2/Wisconsin and examined changes in host peripheral blood gene expression at 16 timepoints over 132 hours. Here we present distinct transcriptional dynamics of host responses unique to asymptomatic and symptomatic infections. We show that symptomatic hosts invoke, simultaneously, multiple pattern recognition receptors-mediated antiviral and inflammatory responses that may relate to virus-induced oxidative stress. In contrast, asymptomatic subjects tightly regulate these responses and exhibit elevated expression of genes that function in antioxidant responses and cell-mediated responses. We reveal an ab initio molecular signature that strongly correlates to symptomatic clinical disease and biomarkers whose expression patterns best discriminate early from late phases of infection. Our results establish a temporal pattern of host molecular responses that differentiates symptomatic from asymptomatic infections and reveals an asymptomatic host-unique non-passive response signature, suggesting novel putative molecular targets for both prognostic assessment and ameliorative therapeutic intervention in seasonal and pandemic influenza.

  15. Preliminary Validation of a New Measure of Negative Response Bias: The Temporal Memory Sequence Test.

    Science.gov (United States)

    Hegedish, Omer; Kivilis, Naama; Hoofien, Dan

    2015-01-01

    The Temporal Memory Sequence Test (TMST) is a new measure of negative response bias (NRB) that was developed to enrich the forced-choice paradigm. The TMST does not resemble the common structure of forced-choice tests and is presented as a temporal recall memory test. The validation sample consisted of 81 participants: 21 healthy control participants, 20 coached simulators, and 40 patients with acquired brain injury (ABI). The TMST had high reliability and significantly high positive correlations with the Test of Memory Malingering and Word Memory Test effort scales. Moreover, the TMST effort scales exhibited high negative correlations with the Glasgow Coma Scale, thus validating the previously reported association between probable malingering and mild traumatic brain injury. A suggested cutoff score yielded acceptable classification rates in the ABI group as well as in the simulator and control groups. The TMST appears to be a promising measure of NRB detection, with respectable rates of reliability and construct and criterion validity.

  16. Extended two-temperature model for ultrafast thermal response of band gap materials upon impulsive optical excitation

    International Nuclear Information System (INIS)

    Shin, Taeho; Teitelbaum, Samuel W.; Wolfson, Johanna; Nelson, Keith A.; Kandyla, Maria

    2015-01-01

    Thermal modeling and numerical simulations have been performed to describe the ultrafast thermal response of band gap materials upon optical excitation. A model was established by extending the conventional two-temperature model that is adequate for metals, but not for semiconductors. It considers the time- and space-dependent density of electrons photoexcited to the conduction band and accordingly allows a more accurate description of the transient thermal equilibration between the hot electrons and lattice. Ultrafast thermal behaviors of bismuth, as a model system, were demonstrated using the extended two-temperature model with a view to elucidating the thermal effects of excitation laser pulse fluence, electron diffusivity, electron-hole recombination kinetics, and electron-phonon interactions, focusing on high-density excitation

  17. Dimensions and disorder specificity of impulsivity in pathological gambling.

    Science.gov (United States)

    Kräplin, Anja; Bühringer, Gerhard; Oosterlaan, Jaap; van den Brink, Wim; Goschke, Thomas; Goudriaan, Anna E

    2014-11-01

    Impulsivity is a core characteristic of pathological gambling (PG), even though the underlying structure and disorder specificity is unclear. This study aimed to explore different dimensions of impulsivity in a clinical sample including PG. Furthermore, we aimed to test which alterations of the impulsivity-related dimensions are disorder specific for PG. Participants were individuals diagnosed with PG (n=51) and two groups also characterized by various impulsive behaviors: an alcohol dependence (AD; n=45) and a Gilles de la Tourette syndrome (GTS; n=49) group. A healthy control (HC; n=53) group was recruited as comparison group. A comprehensive assessment was used including impulsivity-related and antipodal parameters of the Stop Signal Task, Stroop Task, Tower of London Task, Card Playing Task, Iowa Gambling Task and the Barratt Impulsiveness Scale-11. Principal axis factor analysis revealed four impulsivity-related dimensions that were labeled 'self-reported impulsivity', 'prepotent response impulsivity', 'choice impulsivity' and 'motor impulsivity'. The PG group scored significantly higher on all four dimensions compared to the HC group. In contrast, the PG group did not differ on any of the dimensions from the AD or the GTS group, except for 'choice impulsivity' where the PG group exhibited higher factor scores compared to the GTS group. Altogether, PG is associated with generally heightened impulsivity profiles compared to a HC group, which may be further used for intervention strategies. However, heightened scores in the impulsivity dimensions are not disorder specific for PG. Further research on shared or different underlying mechanisms of these overlapping impulsivity impairments is necessary. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Maternal overreactive sympathetic nervous system responses to repeated infant crying predicts risk for impulsive harsh discipline of infants.

    Science.gov (United States)

    Joosen, Katharina J; Mesman, Judi; Bakermans-Kranenburg, Marian J; van Ijzendoorn, Marinus H

    2013-11-01

    Physiological reactivity to repeated infant crying was examined as a predictor of risk for harsh discipline use with 12-month-olds in a longitudinal study with 48 low-income mother-infant dyads. Physiological reactivity was measured while mothers listened to three blocks of infant cry sounds in a standard cry paradigm when their infants were 3 months old. Signs of harsh discipline use were observed during two tasks during a home visit when the infants were 12 months old. Mothers showing signs of harsh discipline (n = 10) with their 12-month-olds were compared to mothers who did not (n = 38) on their sympathetic (skin conductance levels [SCL]) and parasympathetic (respiratory sinus arrhythmia) reactivity to the cry sounds. Results showed a significant interaction effect for sympathetic reactivity only. Mean SCL of harsh-risk mothers showed a significant different response pattern from baseline to crying and onward into the recovery, suggesting that mean SCL of mothers who showed signs of harsh discipline continued to rise across the repeated bouts of cry sounds while, after an initial increase, mean SCL level of the other mothers showed a steady decline. We suggest that harsh parenting is reflected in physiological overreactivity to negative infant signals and discuss our findings from a polyvagal perspective.

  19. Non-parametric temporal modeling of the hemodynamic response function via a liquid state machine.

    Science.gov (United States)

    Avesani, Paolo; Hazan, Hananel; Koilis, Ester; Manevitz, Larry M; Sona, Diego

    2015-10-01

    Standard methods for the analysis of functional MRI data strongly rely on prior implicit and explicit hypotheses made to simplify the analysis. In this work the attention is focused on two such commonly accepted hypotheses: (i) the hemodynamic response function (HRF) to be searched in the BOLD signal can be described by a specific parametric model e.g., double-gamma; (ii) the effect of stimuli on the signal is taken to be linearly additive. While these assumptions have been empirically proven to generate high sensitivity for statistical methods, they also limit the identification of relevant voxels to what is already postulated in the signal, thus not allowing the discovery of unknown correlates in the data due to the presence of unexpected hemodynamics. This paper tries to overcome these limitations by proposing a method wherein the HRF is learned directly from data rather than induced from its basic form assumed in advance. This approach produces a set of voxel-wise models of HRF and, as a result, relevant voxels are filterable according to the accuracy of their prediction in a machine learning framework. This approach is instantiated using a temporal architecture based on the paradigm of Reservoir Computing wherein a Liquid State Machine is combined with a decoding Feed-Forward Neural Network. This splits the modeling into two parts: first a representation of the complex temporal reactivity of the hemodynamic response is determined by a universal global "reservoir" which is essentially temporal; second an interpretation of the encoded representation is determined by a standard feed-forward neural network, which is trained by the data. Thus the reservoir models the temporal state of information during and following temporal stimuli in a feed-back system, while the neural network "translates" this data to fit the specific HRF response as given, e.g. by BOLD signal measurements in fMRI. An empirical analysis on synthetic datasets shows that the learning process can

  20. Prepulse Inhibition of Auditory Cortical Responses in the Caudolateral Superior Temporal Gyrus in Macaca mulatta.

    Science.gov (United States)

    Chen, Zuyue; Parkkonen, Lauri; Wei, Jingkuan; Dong, Jin-Run; Ma, Yuanye; Carlson, Synnöve

    2018-04-01

    Prepulse inhibition (PPI) refers to a decreased response to a startling stimulus when another weaker stimulus precedes it. Most PPI studies have focused on the physiological startle reflex and fewer have reported the PPI of cortical responses. We recorded local field potentials (LFPs) in four monkeys and investigated whether the PPI of auditory cortical responses (alpha, beta, and gamma oscillations and evoked potentials) can be demonstrated in the caudolateral belt of the superior temporal gyrus (STGcb). We also investigated whether the presence of a conspecific, which draws attention away from the auditory stimuli, affects the PPI of auditory cortical responses. The PPI paradigm consisted of Pulse-only and Prepulse + Pulse trials that were presented randomly while the monkey was alone (ALONE) and while another monkey was present in the same room (ACCOMP). The LFPs to the Pulse were significantly suppressed by the Prepulse thus, demonstrating PPI of cortical responses in the STGcb. The PPI-related inhibition of the N1 amplitude of the evoked responses and cortical oscillations to the Pulse were not affected by the presence of a conspecific. In contrast, gamma oscillations and the amplitude of the N1 response to Pulse-only were suppressed in the ACCOMP condition compared to the ALONE condition. These findings demonstrate PPI in the monkey STGcb and suggest that the PPI of auditory cortical responses in the monkey STGcb is a pre-attentive inhibitory process that is independent of attentional modulation.

  1. White Matter Hyperintensities, Medial Temporal Lobe Atrophy, Cortical Atrophy, and Response to Electroconvulsive Therapy in Severely Depressed Elderly Patients

    NARCIS (Netherlands)

    Oudega, Mardien L.; van Exel, Eric; Wattjes, Mike P.; Comijs, Hannie C.; Scheltens, Philip; Barkhof, Frederik; Eikelenboom, Piet; de Craen, Anton J. M.; Beekman, Aartjan T. F.; Stek, Max L.

    2011-01-01

    Objective: Electroconvulsive therapy (ECT) is a valuable treatment option in severely depressed elderly patients. Structural abnormalities in the brain, such as white matter hyperintensities, medial temporal lobe atrophy (MTA), or global cortical atrophy, may influence therapeutic response. The

  2. Temporal envelope processing in the human auditory cortex: response and interconnections of auditory cortical areas.

    Science.gov (United States)

    Gourévitch, Boris; Le Bouquin Jeannès, Régine; Faucon, Gérard; Liégeois-Chauvel, Catherine

    2008-03-01

    Temporal envelope processing in the human auditory cortex has an important role in language analysis. In this paper, depth recordings of local field potentials in response to amplitude modulated white noises were used to design maps of activation in primary, secondary and associative auditory areas and to study the propagation of the cortical activity between them. The comparison of activations between auditory areas was based on a signal-to-noise ratio associated with the response to amplitude modulation (AM). The functional connectivity between cortical areas was quantified by the directed coherence (DCOH) applied to auditory evoked potentials. This study shows the following reproducible results on twenty subjects: (1) the primary auditory cortex (PAC), the secondary cortices (secondary auditory cortex (SAC) and planum temporale (PT)), the insular gyrus, the Brodmann area (BA) 22 and the posterior part of T1 gyrus (T1Post) respond to AM in both hemispheres. (2) A stronger response to AM was observed in SAC and T1Post of the left hemisphere independent of the modulation frequency (MF), and in the left BA22 for MFs 8 and 16Hz, compared to those in the right. (3) The activation and propagation features emphasized at least four different types of temporal processing. (4) A sequential activation of PAC, SAC and BA22 areas was clearly visible at all MFs, while other auditory areas may be more involved in parallel processing upon a stream originating from primary auditory area, which thus acts as a distribution hub. These results suggest that different psychological information is carried by the temporal envelope of sounds relative to the rate of amplitude modulation.

  3. Temporal partitioning of adaptive responses of the murine heart to fasting.

    Science.gov (United States)

    Brewer, Rachel A; Collins, Helen E; Berry, Ryan D; Brahma, Manoja K; Tirado, Brian A; Peliciari-Garcia, Rodrigo A; Stanley, Haley L; Wende, Adam R; Taegtmeyer, Heinrich; Rajasekaran, Namakkal Soorappan; Darley-Usmar, Victor; Zhang, Jianhua; Frank, Stuart J; Chatham, John C; Young, Martin E

    2018-03-15

    Recent studies suggest that the time of day at which food is consumed dramatically influences clinically-relevant cardiometabolic parameters (e.g., adiposity, insulin sensitivity, and cardiac function). Meal feeding benefits may be the result of daily periods of feeding and/or fasting, highlighting the need for improved understanding of the temporal adaptation of cardiometabolic tissues (e.g., heart) to fasting. Such studies may provide mechanistic insight regarding how time-of-day-dependent feeding/fasting cycles influence cardiac function. We hypothesized that fasting during the sleep period elicits beneficial adaptation of the heart at transcriptional, translational, and metabolic levels. To test this hypothesis, temporal adaptation was investigated in wild-type mice fasted for 24-h, or for either the 12-h light/sleep phase or the 12-h dark/awake phase. Fasting maximally induced fatty acid responsive genes (e.g., Pdk4) during the dark/active phase; transcriptional changes were mirrored at translational (e.g., PDK4) and metabolic flux (e.g., glucose/oleate oxidation) levels. Similarly, maximal repression of myocardial p-mTOR and protein synthesis rates occurred during the dark phase; both parameters remained elevated in the heart of fasted mice during the light phase. In contrast, markers of autophagy (e.g., LC3II) exhibited peak responses to fasting during the light phase. Collectively, these data show that responsiveness of the heart to fasting is temporally partitioned. Autophagy peaks during the light/sleep phase, while repression of glucose utilization and protein synthesis is maximized during the dark/active phase. We speculate that sleep phase fasting may benefit cardiac function through augmentation of protein/cellular constituent turnover. Copyright © 2018 Elsevier Inc. All rights reserved.

  4. Effects of temporally biased watering on the nitrogen response of Chenopodium album

    Science.gov (United States)

    Kinugasa, Toshihiko; Hozumi, Yumi

    2017-07-01

    Plant growth responses to an increasing N deposition are stimulated by an increase in annual precipitation, but such a stimulation has not always been found. We hypothesized that the effect of precipitation on plant N responses can change with temporally biased precipitation: a plant N response will be suppressed when precipitation is lower in the late growing period because larger plants are more susceptible to water limitations. We grew Chenopodium album under a high and low N application level with three watering patterns while maintaining the total supplied watering amount during the experimental period: constant watering, low watering in the first period and high watering in the latter period, and high watering in the first period and low watering in the latter period. The watering pattern did not affect plant dry mass under low N conditions. The plant dry mass under high N conditions was reduced by low watering in the first period, but the reduction was fully compensated in the subsequent high watering period by the stimulation of photosynthesis. Low watering following high watering under high N conditions did not suppress plant growth, but partial leaf wilting was observed at the end of the experimental period. Finally, at the end of the experiment, the response of plant dry mass to N was not different among the watering patterns. We concluded that a plant's response to increasing N deposition could be affected by temporally biased precipitation, depending on the scale of the precipitation bias and the ability of the plant to compensate or mitigate growth inhibition due to a water deficit. Precipitation deficits later in the growing period may be more detrimental to plant growth and can reduce plant responses to an increasing N deposition.

  5. Assessing signal-driven mechanism in neonates: brain responses to temporally and spectrally different sounds

    Directory of Open Access Journals (Sweden)

    Yasuyo eMinagawa-Kawai

    2011-06-01

    Full Text Available Past studies have found that in adults that acoustic properties of sound signals (such as fast vs. slow temporal features differentially activate the left and right hemispheres, and some have hypothesized that left-lateralization for speech processing may follow from left-lateralization to rapidly changing signals. Here, we tested whether newborns’ brains show some evidence of signal-specific lateralization responses using near-infrared spectroscopy (NIRS and auditory stimuli that elicits lateralized responses in adults, composed of segments that vary in duration and spectral diversity. We found significantly greater bilateral responses of oxygenated hemoglobin (oxy-Hb in the temporal areas for stimuli with a minimum segment duration of 21 ms, than stimuli with a minimum segment duration of 667 ms. However, we found no evidence for hemispheric asymmetries dependent on the stimulus characteristics. We hypothesize that acoustic-based functional brain asymmetries may develop throughout early infancy, and discuss their possible relationship with brain asymmetries for language.

  6. Temporal variation overshadows the response of leaf litter microbial communities to simulated global change.

    Science.gov (United States)

    Matulich, Kristin L; Weihe, Claudia; Allison, Steven D; Amend, Anthony S; Berlemont, Renaud; Goulden, Michael L; Kimball, Sarah; Martiny, Adam C; Martiny, Jennifer B H

    2015-11-01

    Bacteria and fungi drive the decomposition of dead plant biomass (litter), an important step in the terrestrial carbon cycle. Here we investigate the sensitivity of litter microbial communities to simulated global change (drought and nitrogen addition) in a California annual grassland. Using 16S and 28S rDNA amplicon pyrosequencing, we quantify the response of the bacterial and fungal communities to the treatments and compare these results to background, temporal (seasonal and interannual) variability of the communities. We found that the drought and nitrogen treatments both had significant effects on microbial community composition, explaining 2-6% of total compositional variation. However, microbial composition was even more strongly influenced by seasonal and annual variation (explaining 14-39%). The response of microbial composition to drought varied by season, while the effect of the nitrogen addition treatment was constant through time. These compositional responses were similar in magnitude to those seen in microbial enzyme activities and the surrounding plant community, but did not correspond to a consistent effect on leaf litter decomposition rate. Overall, these patterns indicate that, in this ecosystem, temporal variability in the composition of leaf litter microorganisms largely surpasses that expected in a short-term global change experiment. Thus, as for plant communities, future microbial communities will likely be determined by the interplay between rapid, local background variability and slower, global changes.

  7. Temporal response of endogenous neural progenitor cells following injury to the adult rat spinal cord

    Directory of Open Access Journals (Sweden)

    Yilin eMao

    2016-03-01

    Full Text Available A pool of endogenous neural progenitor cells found in the ependymal layer and the sub-ependymal area of the spinal cord are reported to upregulate nestin in response to traumatic spinal cord injury. These cells could potentially be manipulated within a critical time period offering one innovative approach to the repair of spinal cord injury. However, little is known about the temporal response of endogenous neural progenitor cells following spinal cord injury. This study used a mild contusion injury in rat spinal cord and immunohistochemistry to determine the temporal response of ependymal neural progenitor cells following injury and their correlation to astrocyte activation at the lesion site. The results from the study demonstrated that Nestin staining intensity at the central canal peaked at 24 hours post-injury and then gradually declined over time. Reactive astrocytes double labelled by Nestin and GFAP were found at the lesion edge and commenced to form the glial scar from 1 week after injury. We conclude that the critical time period for manipulating endogenous neural progenitor cells following a spinal cord injury in rats is between 24 hrs when nestin expression in ependymal cells is increased and 1 week when astrocytes are activated in large numbers.

  8. Temporal dynamics of hot desert microbial communities reveal structural and functional responses to water input

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Alacia; Valverde, Angel; Ramond, Jean-Baptiste; Makhalanyane, Thulani P.; Jansson, Janet K.; Hopkins, David W.; Aspray, Thomas J.; Seely, Mary; Trindade, Marla I.; Cowan, Don A.

    2016-09-29

    The temporal dynamics of desert soil microbial communities are poorly understood. Given the implications for ecosystem functioning under a global change scenario, a better understanding of desert microbial community stability is crucial. Here, we sampled soils in the central Namib Desert on sixteen different occasions over a one-year period. Using Illumina-based amplicon sequencing of the 16S rRNA gene, we found that α-diversity (richness) was more variable at a given sampling date (spatial variability) than over the course of one year (temporal variability). Community composition remained essentially unchanged across the first 10 months, indicating that spatial sampling might be more important than temporal sampling when assessing β-diversity patterns in desert soils. However, a major shift in microbial community composition was found following a single precipitation event. This shift in composition was associated with a rapid increase in CO2 respiration and productivity, supporting the view that desert soil microbial communities respond rapidly to re-wetting and that this response may be the result of both taxon-specific selection and changes in the availability or accessibility of organic substrates. Recovery to quasi pre-disturbance community composition was achieved within one month after rainfall.

  9. Amygdala and fusiform gyrus temporal dynamics: Responses to negative facial expressions

    Directory of Open Access Journals (Sweden)

    Rauch Scott L

    2008-05-01

    Full Text Available Abstract Background The amygdala habituates in response to repeated human facial expressions; however, it is unclear whether this brain region habituates to schematic faces (i.e., simple line drawings or caricatures of faces. Using an fMRI block design, 16 healthy participants passively viewed repeated presentations of schematic and human neutral and negative facial expressions. Percent signal changes within anatomic regions-of-interest (amygdala and fusiform gyrus were calculated to examine the temporal dynamics of neural response and any response differences based on face type. Results The amygdala and fusiform gyrus had a within-run "U" response pattern of activity to facial expression blocks. The initial block within each run elicited the greatest activation (relative to baseline and the final block elicited greater activation than the preceding block. No significant differences between schematic and human faces were detected in the amygdala or fusiform gyrus. Conclusion The "U" pattern of response in the amygdala and fusiform gyrus to facial expressions suggests an initial orienting, habituation, and activation recovery in these regions. Furthermore, this study is the first to directly compare brain responses to schematic and human facial expressions, and the similarity in brain responses suggest that schematic faces may be useful in studying amygdala activation.

  10. Clock-dependent temporal regulation of IL-33/ST2-mediated mast cell response.

    Science.gov (United States)

    Kawauchi, Takahiro; Ishimaru, Kayoko; Nakamura, Yuki; Nakano, Nobuhiro; Hara, Mutsuko; Ogawa, Hideoki; Okumura, Ko; Shibata, Shigenobu; Nakao, Atsuhito

    2017-07-01

    Interleukin-33 (IL-33) is an alarmin cytokine that binds to the interleukin 1 receptor-like 1 protein ST2. Clock is a key circadian gene that is essential for endogenous clockworks in mammals. This study investigated whether Clock temporally regulated IL-33-mediated responses in mast cells. The kinetics of IL-33-mediated IL-6, IL-13, and TNF-α productions were compared between bone marrow-derived mast cells (BMMCs) from wild-type and Clock-mutated mice (Clock Δ19/Δ19 mice). The kinetics of the neutrophil influx into the peritoneal cavity or expression of IL-13 and Gob-5 in the lung in response to IL-33 were compared between wild-type and Clock Δ19/Δ19 mice. We also examined the kinetics of ST2 expression in mast cells and its association with Clock expression. There was a time-of-day-dependent variation in IL-33-mediated IL-6, IL-13, and TNF-α production in wild-type BMMCs, which was absent in Clock-mutated BMMCs. IL-33-induced neutrophil infiltration into the peritoneal cavity also showed a time-of-day-dependent variation in wild-type mice, which was absent in Clock Δ19/Δ19 mice. Furthermore, IL-33-induced IL-13 and Gob-5 expression in the lung exhibited a time-of-day-dependent variation in wild-type mice. These temporal variations in IL-33-mediated mast cell responses were associated with temporal variations of ST2 expression in mast cells. In addition, CLOCK bound to the promoter region of ST2 and Clock deletion resulted in down-regulation of ST2 expression in mast cells. CLOCK temporally gates mast cell responses to IL-33 via regulation of ST2 expression. Our findings provide novel insights into IL-33/mast cell-associated physiology and pathologies. Copyright © 2017 Japanese Society of Allergology. Production and hosting by Elsevier B.V. All rights reserved.

  11. Ghosts of the past and dreams of the future: the impact of temporal focus on responses to contextual ingroup devaluation.

    Science.gov (United States)

    Rabinovich, Anna; Morton, Thomas A

    2012-03-01

    The authors investigated the impact of temporal focus on group members' responses to contextual ingroup devaluation. Four experimental studies demonstrated that following an induction of negative ingroup evaluation, participants primed with a past temporal focus reported behavioral intentions more consistent with this negative appraisal than participants primed with a future temporal focus. This effect was apparent only when a negative (but not a positive) evaluation was induced, and only among highly identified group members. Importantly, the interplay between temporal focus and group identification on relevant intentions was mediated by individual self-esteem, suggesting that focus on the future may be conducive to separating negative ingroup appraisals from individual self-evaluations. Taken together, the findings suggest that high identifiers' responses to ingroup evaluations may be predicated on their temporal focus: A focus on the past may lock such individuals within their group's history, whereas a vision of the future may open up opportunities for change.

  12. Middle components of the auditory evoked response in bilateral temporal lobe lesions. Report on a patient with auditory agnosia

    DEFF Research Database (Denmark)

    Parving, A; Salomon, G; Elberling, Claus

    1980-01-01

    An investigation of the middle components of the auditory evoked response (10--50 msec post-stimulus) in a patient with auditory agnosia is reported. Bilateral temporal lobe infarctions were proved by means of brain scintigraphy, CAT scanning, and regional cerebral blood flow measurements...... that the middle components cannot be generated exclusively, if at all, in the primary auditory cortex, located in the temporal lobe. Furthermore, the responses are found to be of neurogenic origin according to the methodological procedure applied....

  13. Contrasting spatial and temporal responses of bird communities to landscape changes.

    Science.gov (United States)

    Bonthoux, Sébastien; Barnagaud, Jean-Yves; Goulard, Michel; Balent, Gérard

    2013-06-01

    Quantifying the impact of land-use changes on biodiversity is a major challenge in conservation ecology. Static spatial relationships between bird communities and agricultural landscapes have been extensively studied. Yet, their ability to mirror the effects of temporal land-use dynamics remains to be demonstrated. Here, we test whether such space-for-time substitution approaches are relevant for explaining temporal variations in farmland bird communities. We surveyed 256 bird communities in an agricultural landscape in southwest France at the same locations in 1982 and 2007, and quantified the same seven landscape descriptors for each period. We compared the effects of spatial and temporal landscape changes over this 25-year period on bird species distributions and three community-level metrics: species richness and two community indices reflecting birds' specialisation regarding local vegetation structure (local CSI) and landscape composition (landscape CSI). Landscape heterogeneity decreased between 1982 and 2007 and crop area increased sharply at the expense of grassland as a result of agricultural intensification. We found that the correlations between temporal changes in bird distributions or community metrics and landscape components were less consistent than their spatial relationships in each year. This result advocates caution when using a space-for-time substitution approach to assess the effects of landscape changes on biodiversity. Additionally, community metrics showed contrasted responses to landscape changes. Species richness and local CSI for each period were negatively related to the area of crops and positively related to landscape heterogeneity. Conversely, the landscape CSI was positively related to the area of crop and negatively to landscape heterogeneity. To understand the ecological processes linked to changes in farm landscapes, our study underlines the need to develop long-term studies with bird and habitat data collected during several

  14. A sum-over-paths algorithm for third-order impulse-response moment extraction within RC IC-interconnect networks

    Science.gov (United States)

    Wojcik, E. A.; Ni, D.; Lam, T. M.; Le Coz, Y. L.

    2015-07-01

    We have created the first stochastic SoP (Sum-over-Paths) algorithm to extract third-order impulse-response (IR) moment within RC IC interconnects. It employs a newly discovered Feynman SoP Postulate. Importantly, our algorithm maintains computational efficiency and full parallelism. Our approach begins with generation of s-domain nodal-voltage equations. We then perform a Taylor-series expansion of the circuit transfer function. These expansions yield transition diagrams involving mathematical coupling constants, or weight factors, in integral powers of complex frequency s. Our SoP Postulate enables stochastic evaluation of path sums within the circuit transition diagram to order s3-corresponding to the order of IR moment (m3) we seek here. We furnish, for the first time, an informal algebraic proof independently validating our SoP Postulate and algorithm. We list, as well, detailed procedural steps, suitable for coding, that define an efficient stochastic algorithm for m3 IR extraction. Origins of the algorithm's statistical "capacitor-number cubed" correction and "double-counting" weight factors are explained, for completeness. Our algorithm was coded and successfully tested against exact analytical solutions for 3-, 5-, and 10-stage RC lines. We achieved better than 0.65% 1-σ error convergence, after only 10K statistical samples, in less than 1 s of 2-GHz Pentium® execution time. These results continue to suggest that stochastic SoP algorithms may find useful application in circuit analysis of massively coupled networks, such as those encountered in high-end digital IC-interconnect CAD.

  15. Trans-middle temporal gyrus selective amygdalohippocampectomy for medically intractable mesial temporal lobe epilepsy in adults: seizure response rates, complications, and neuropsychological outcomes.

    Science.gov (United States)

    Bandt, S Kathleen; Werner, Nicole; Dines, Jennifer; Rashid, Samiya; Eisenman, Lawrence N; Hogan, R Edward; Leuthardt, Eric C; Dowling, Joshua

    2013-07-01

    Selective amygdalohippocampectomy (AHC) has evolved to encompass a variety of techniques to resect the mesial temporal lobe. To date, there have been few large-scale evaluations of trans-middle temporal gyrus selective AHC. The authors examine a large series of patients who have undergone the trans-middle temporal gyrus AHC and assess its clinical and neuropsychological impact. A series of 76 adult patients underwent selective AHC via the trans-middle temporal gyrus approach over a 10-year period, 19 of whom underwent pre- and postoperative neuropsychological evaluations. Favorable seizure response rates were achieved (92% Engel class I or II), with very low surgical morbidity and no mortality. Postoperative neuropsychological assessment revealed a decline in verbal memory for the left AHC group. No postoperative memory decline was identified for the right AHC group, but rather some improvements were noted within this group. The trans-middle temporal gyrus selective AHC is a safe and effective choice for management of medically refractory epilepsy in adults. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. The relation between auditory-nerve temporal responses and perceptual rate integration in cochlear implants.

    Science.gov (United States)

    Hughes, Michelle L; Baudhuin, Jacquelyn L; Goehring, Jenny L

    2014-10-01

    The purpose of this study was to examine auditory-nerve temporal response properties and their relation to psychophysical threshold for electrical pulse trains of varying rates ("rate integration"). The primary hypothesis was that better rate integration (steeper slope) would be correlated with smaller decrements in ECAP amplitude as a function of stimulation rate (shallower slope of the amplitude-rate function), reflecting a larger percentage of the neural population contributing more synchronously to each pulse in the train. Data were obtained for 26 ears in 23 cochlear-implant recipients. Electrically evoked compound action potential (ECAP) amplitudes were measured in response to each of 21 pulses in a pulse train for the following rates: 900, 1200, 1800, 2400, and 3500 pps. Psychophysical thresholds were obtained using a 3-interval, forced-choice adaptive procedure for 300-ms pulse trains of the same rates as used for the ECAP measures, which formed the rate-integration function. For each electrode, the slope of the psychophysical rate-integration function was compared to the following ECAP measures: (1) slope of the function comparing average normalized ECAP amplitude across pulses versus stimulation rate ("adaptation"), (2) the rate that produced the maximum alternation depth across the pulse train, and (3) rate at which the alternating pattern ceased (stochastic rate). Results showed no significant relations between the slope of the rate-integration function and any of the ECAP measures when data were collapsed across subjects. However, group data showed that both threshold and average ECAP amplitude decreased with increased stimulus rate, and within-subject analyses showed significant positive correlations between psychophysical thresholds and mean ECAP response amplitudes across the pulse train. These data suggest that ECAP temporal response patterns are complex and further study is required to better understand the relative contributions of adaptation

  17. Transcriptomic analysis of the temporal host response to skin infestation with the ectoparasitic mite Psoroptes ovis

    Directory of Open Access Journals (Sweden)

    McNeilly Tom N

    2010-11-01

    Full Text Available Abstract Background Infestation of ovine skin with the ectoparasitic mite Psoroptes ovis results in a rapid cutaneous immune response, leading to the crusted skin lesions characteristic of sheep scab. Little is known regarding the mechanisms by which such a profound inflammatory response is instigated and to identify novel vaccine and drug targets a better understanding of the host-parasite relationship is essential. The main objective of this study was to perform a combined network and pathway analysis of the in vivo skin response to infestation with P. ovis to gain a clearer understanding of the mechanisms and signalling pathways involved. Results Infestation with P. ovis resulted in differential expression of 1,552 genes over a 24 hour time course. Clustering by peak gene expression enabled classification of genes into temporally related groupings. Network and pathway analysis of clusters identified key signalling pathways involved in the host response to infestation. The analysis implicated a number of genes with roles in allergy and inflammation, including pro-inflammatory cytokines (IL1A, IL1B, IL6, IL8 and TNF and factors involved in immune cell activation and recruitment (SELE, SELL, SELP, ICAM1, CSF2, CSF3, CCL2 and CXCL2. The analysis also highlighted the influence of the transcription factors NF-kB and AP-1 in the early pro-inflammatory response, and demonstrated a bias towards a Th2 type immune response. Conclusions This study has provided novel insights into the signalling mechanisms leading to the development of a pro-inflammatory response in sheep scab, whilst providing crucial information regarding the nature of mite factors that may trigger this response. It has enabled the elucidation of the temporal patterns by which the immune system is regulated following exposure to P. ovis, providing novel insights into the mechanisms underlying lesion development. This study has improved our existing knowledge of the host response to P

  18. Subclinical delusional thinking predicts lateral temporal cortex responses during social reflection.

    Science.gov (United States)

    Brent, Benjamin K; Coombs, Garth; Keshavan, Matcheri S; Seidman, Larry J; Moran, Joseph M; Holt, Daphne J

    2014-03-01

    Neuroimaging studies have demonstrated associations between delusions in psychotic disorders and abnormalities of brain areas involved in social cognition, including medial prefrontal cortex (MPFC), posterior cingulate cortex, and lateral temporal cortex (LTC). General population studies have linked subclinical delusional thinking to impaired social cognition, raising the question of whether a specific pattern of brain activity during social perception is associated with delusional beliefs. Here, we tested the hypothesis that subclinical delusional thinking is associated with changes in neural function, while subjects made judgments about themselves or others ['social reflection' (SR)]. Neural responses during SR and non-social tasks, as well as resting-state activity, were measured using functional magnetic resonance imaging in 22 healthy subjects. Delusional thinking was measured using the Peters et al. Delusions Inventory. Delusional thinking was negatively correlated with responses of the left LTC during SR (r = -0.61, P = 0.02, Bonferroni corrected), and connectivity between the left LTC and left ventral MPFC, and was positively correlated with connectivity between the left LTC and the right middle frontal and inferior temporal cortices. Thus, delusional thinking in the general population may be associated with reduced activity and aberrant functional connectivity of cortical areas involved in SR.

  19. Impulsive generalized function synchronization of complex dynamical networks

    International Nuclear Information System (INIS)

    Zhang, Qunjiao; Chen, Juan; Wan, Li

    2013-01-01

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

  20. Spatial Attention and Temporal Expectation Under Timed Uncertainty Predictably Modulate Neuronal Responses in Monkey V1

    Science.gov (United States)

    Sharma, Jitendra; Sugihara, Hiroki; Katz, Yarden; Schummers, James; Tenenbaum, Joshua; Sur, Mriganka

    2015-01-01

    The brain uses attention and expectation as flexible devices for optimizing behavioral responses associated with expected but unpredictably timed events. The neural bases of attention and expectation are thought to engage higher cognitive loci; however, their influence at the level of primary visual cortex (V1) remains unknown. Here, we asked whether single-neuron responses in monkey V1 were influenced by an attention task of unpredictable duration. Monkeys covertly attended to a spot that remained unchanged for a fixed period and then abruptly disappeared at variable times, prompting a lever release for reward. We show that monkeys responded progressively faster and performed better as the trial duration increased. Neural responses also followed monkey's task engagement—there was an early, but short duration, response facilitation, followed by a late but sustained increase during the time monkeys expected the attention spot to disappear. This late attentional modulation was significantly and negatively correlated with the reaction time and was well explained by a modified hazard function. Such bimodal, time-dependent changes were, however, absent in a task that did not require explicit attentional engagement. Thus, V1 neurons carry reliable signals of attention and temporal expectation that correlate with predictable influences on monkeys' behavioral responses. PMID:24836689

  1. Genetic association of impulsivity in young adults: a multivariate study.

    Science.gov (United States)

    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

    2014-09-30

    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.

  2. Investigation of thermal and temporal responses of ionization chambers in radiation dosimetry.

    Science.gov (United States)

    AlMasri, Hussein; Funyu, Akira; Kakinohana, Yasumasa; Murayama, Sadayuki

    2012-07-01

    The ionization chamber is a primary dosimeter that is used in radiation dosimetry. Generally, the ion chamber response requires temperature/pressure correction according to the ideal gas law. However, this correction does not consider the thermal volume effect of chambers. The temporal and thermal volume effects of various chambers (CC01, CC13, NACP parallel-plate, PTW) with different wall and electrode materials have been studied in a water phantom. Measurements were done after heating the water with a suitable heating system, and chambers were submerged for a sufficient time to allow for temperature equilibrium. Temporal results show that all chambers equilibrate quickly in water. The equilibration time was between 3 and 5 min for all chambers. Thermal results show that all chambers expanded in response to heating except for the PTW, which contracted. This might be explained by the differences in the volumes of all chambers and also by the difference in wall material composition of PTW from the other chambers. It was found that the smallest chamber, CC01, showed the greatest expansion. The magnitude of the expansion was ~1, 0.8, and 0.9% for CC01, CC13, and parallel-plate chambers, respectively, in the temperature range of 295-320 K. The magnitude of the detected contraction was <0.3% for PTW in the same temperature range. For absolute dosimetry, it is necessary to make corrections for the ion chamber response, especially for small ion chambers like the CC01. Otherwise, room and water phantom temperatures should remain within a close range.

  3. Retinal Vascular and Oxygen Temporal Dynamic Responses to Light Flicker in Humans.

    Science.gov (United States)

    Felder, Anthony E; Wanek, Justin; Blair, Norman P; Shahidi, Mahnaz

    2017-11-01

    To mathematically model the temporal dynamic responses of retinal vessel diameter (D), oxygen saturation (SO2), and inner retinal oxygen extraction fraction (OEF) to light flicker and to describe their responses to its cessation in humans. In 16 healthy subjects (age: 60 ± 12 years), retinal oximetry was performed before, during, and after light flicker stimulation. At each time point, five metrics were measured: retinal arterial and venous D (DA, DV) and SO2 (SO2A, SO2V), and OEF. Intra- and intersubject variability of metrics was assessed by coefficient of variation of measurements before flicker within and among subjects, respectively. Metrics during flicker were modeled by exponential functions to determine the flicker-induced steady state metric values and the time constants of changes. Metrics after the cessation of flicker were compared to those before flicker. Intra- and intersubject variability for all metrics were less than 6% and 16%, respectively. At the flicker-induced steady state, DA and DV increased by 5%, SO2V increased by 7%, and OEF decreased by 13%. The time constants of DA and DV (14, 15 seconds) were twofold smaller than those of SO2V and OEF (39, 34 seconds). Within 26 seconds after the cessation of flicker, all metrics were not significantly different from before flicker values (P ≥ 0.07). Mathematical modeling revealed considerable differences in the time courses of changes among metrics during flicker, indicating flicker duration should be considered separately for each metric. Future application of this method may be useful to elucidate alterations in temporal dynamic responses to light flicker due to retinal diseases.

  4. Relaxation response induces temporal transcriptome changes in energy metabolism, insulin secretion and inflammatory pathways.

    Directory of Open Access Journals (Sweden)

    Manoj K Bhasin

    Full Text Available The relaxation response (RR is the counterpart of the stress response. Millennia-old practices evoking the RR include meditation, yoga and repetitive prayer. Although RR elicitation is an effective therapeutic intervention that counteracts the adverse clinical effects of stress in disorders including hypertension, anxiety, insomnia and aging, the underlying molecular mechanisms that explain these clinical benefits remain undetermined. To assess rapid time-dependent (temporal genomic changes during one session of RR practice among healthy practitioners with years of RR practice and also in novices before and after 8 weeks of RR training, we measured the transcriptome in peripheral blood prior to, immediately after, and 15 minutes after listening to an RR-eliciting or a health education CD. Both short-term and long-term practitioners evoked significant temporal gene expression changes with greater significance in the latter as compared to novices. RR practice enhanced expression of genes associated with energy metabolism, mitochondrial function, insulin secretion and telomere maintenance, and reduced expression of genes linked to inflammatory response and stress-related pathways. Interactive network analyses of RR-affected pathways identified mitochondrial ATP synthase and insulin (INS as top upregulated critical molecules (focus hubs and NF-κB pathway genes as top downregulated focus hubs. Our results for the first time indicate that RR elicitation, particularly after long-term practice, may evoke its downstream health benefits by improving mitochondrial energy production and utilization and thus promoting mitochondrial resiliency through upregulation of ATPase and insulin function. Mitochondrial resiliency might also be promoted by RR-induced downregulation of NF-κB-associated upstream and downstream targets that mitigates stress.

  5. On the temporal dynamics of spatial stimulus-response transfer between spatial incompatibility and Simon tasks.

    Science.gov (United States)

    Ivanoff, Jason; Blagdon, Ryan; Feener, Stefanie; McNeil, Melanie; Muir, Paul H

    2014-01-01

    The Simon effect refers to the performance (response time and accuracy) advantage for responses that spatially correspond to the task-irrelevant location of a stimulus. It has been attributed to a natural tendency to respond toward the source of stimulation. When location is task-relevant, however, and responses are intentionally directed away (incompatible) or toward (compatible) the source of the stimulation, there is also an advantage for spatially compatible responses over spatially incompatible responses. Interestingly, a number of studies have demonstrated a reversed, or reduced, Simon effect following practice with a spatial incompatibility task. One interpretation of this finding is that practicing a spatial incompatibility task disables the natural tendency to respond toward stimuli. Here, the temporal dynamics of this stimulus-response (S-R) transfer were explored with speed-accuracy trade-offs (SATs). All experiments used the mixed-task paradigm in which Simon and spatial compatibility/incompatibility tasks were interleaved across blocks of trials. In general, bidirectional S-R transfer was observed: while the spatial incompatibility task had an influence on the Simon effect, the task-relevant S-R mapping of the Simon task also had a small impact on congruency effects within the spatial compatibility and incompatibility tasks. These effects were generally greater when the task contexts were similar. Moreover, the SAT analysis of performance in the Simon task demonstrated that the tendency to respond to the location of the stimulus was not eliminated because of the spatial incompatibility task. Rather, S-R transfer from the spatial incompatibility task appeared to partially mask the natural tendency to respond to the source of stimulation with a conflicting inclination to respond away from it. These findings support the use of SAT methodology to quantitatively describe rapid response tendencies.

  6. On the temporal dynamics of spatial stimulus-response transfer between spatial incompatibility and Simon tasks

    Science.gov (United States)

    Ivanoff, Jason; Blagdon, Ryan; Feener, Stefanie; McNeil, Melanie; Muir, Paul H.

    2014-01-01

    The Simon effect refers to the performance (response time and accuracy) advantage for responses that spatially correspond to the task-irrelevant location of a stimulus. It has been attributed to a natural tendency to respond toward the source of stimulation. When location is task-relevant, however, and responses are intentionally directed away (incompatible) or toward (compatible) the source of the stimulation, there is also an advantage for spatially compatible responses over spatially incompatible responses. Interestingly, a number of studies have demonstrated a reversed, or reduced, Simon effect following practice with a spatial incompatibility task. One interpretation of this finding is that practicing a spatial incompatibility task disables the natural tendency to respond toward stimuli. Here, the temporal dynamics of this stimulus-response (S-R) transfer were explored with speed-accuracy trade-offs (SATs). All experiments used the mixed-task paradigm in which Simon and spatial compatibility/incompatibility tasks were interleaved across blocks of trials. In general, bidirectional S-R transfer was observed: while the spatial incompatibility task had an influence on the Simon effect, the task-relevant S-R mapping of the Simon task also had a small impact on congruency effects within the spatial compatibility and incompatibility tasks. These effects were generally greater when the task contexts were similar. Moreover, the SAT analysis of performance in the Simon task demonstrated that the tendency to respond to the location of the stimulus was not eliminated because of the spatial incompatibility task. Rather, S-R transfer from the spatial incompatibility task appeared to partially mask the natural tendency to respond to the source of stimulation with a conflicting inclination to respond away from it. These findings support the use of SAT methodology to quantitatively describe rapid response tendencies. PMID:25191217

  7. Temporal Analyses of the Response of Intervertebral Disc Cells and Mesenchymal Stem Cells to Nutrient Deprivation

    Directory of Open Access Journals (Sweden)

    Sarah A. Turner

    2016-01-01

    Full Text Available Much emphasis has been placed recently on the repair of degenerate discs using implanted cells, such as disc cells or bone marrow derived mesenchymal stem cells (MSCs. This study examines the temporal response of bovine and human nucleus pulposus (NP cells and MSCs cultured in monolayer following exposure to altered levels of glucose (0, 3.15, and 4.5 g/L and foetal bovine serum (0, 10, and 20% using an automated time-lapse imaging system. NP cells were also exposed to the cell death inducers, hydrogen peroxide and staurosporine, in comparison to serum starvation. We have demonstrated that human NP cells show an initial “shock” response to reduced nutrition (glucose. However, as time progresses, NP cells supplemented with serum recover with minimal evidence of cell death. Human NP cells show no evidence of proliferation in response to nutrient supplementation, whereas MSCs showed greater response to increased nutrition. When specifically inducing NP cell death with hydrogen peroxide and staurosporine, as expected, the cell number declined. These results support the concept that implanted NP cells or MSCs may be capable of survival in the nutrient-poor environment of the degenerate human disc, which has important clinical implications for the development of IVD cell therapies.

  8. Applied impulsive mathematical models

    CERN Document Server

    Stamova, Ivanka

    2016-01-01

    Using the theory of impulsive differential equations, this book focuses on mathematical models which reflect current research in biology, population dynamics, neural networks and economics. The authors provide the basic background from the fundamental theory and give a systematic exposition of recent results related to the qualitative analysis of impulsive mathematical models. Consisting of six chapters, the book presents many applicable techniques, making them available in a single source easily accessible to researchers interested in mathematical models and their applications. Serving as a valuable reference, this text is addressed to a wide audience of professionals, including mathematicians, applied researchers and practitioners.

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

    Science.gov (United States)

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

    2014-01-01

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

  10. Visual cortex responses reflect temporal structure of continuous quasi-rhythmic sensory stimulation.

    Science.gov (United States)

    Keitel, Christian; Thut, Gregor; Gross, Joachim

    2017-02-01

    Neural processing of dynamic continuous visual input, and cognitive influences thereon, are frequently studied in paradigms employing strictly rhythmic stimulation. However, the temporal structure of natural stimuli is hardly ever fully rhythmic but possesses certain spectral bandwidths (e.g. lip movements in speech, gestures). Examining periodic brain responses elicited by strictly rhythmic stimulation might thus represent ideal, yet isolated cases. Here, we tested how the visual system reflects quasi-rhythmic stimulation with frequencies continuously varying within ranges of classical theta (4-7Hz), alpha (8-13Hz) and beta bands (14-20Hz) using EEG. Our findings substantiate a systematic and sustained neural phase-locking to stimulation in all three frequency ranges. Further, we found that allocation of spatial attention enhances EEG-stimulus locking to theta- and alpha-band stimulation. Our results bridge recent findings regarding phase locking ("entrainment") to quasi-rhythmic visual input and "frequency-tagging" experiments employing strictly rhythmic stimulation. We propose that sustained EEG-stimulus locking can be considered as a continuous neural signature of processing dynamic sensory input in early visual cortices. Accordingly, EEG-stimulus locking serves to trace the temporal evolution of rhythmic as well as quasi-rhythmic visual input and is subject to attentional bias. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  11. Right Fronto-Temporal EEG can Differentiate the Affective Responses to Award-Winning Advertisements.

    Science.gov (United States)

    Wang, Regina W Y; Huarng, Shy-Peih; Chuang, Shang-Wen

    2018-04-01

    Affective engineering aims to improve service/product design by translating the customer's psychological feelings. Award-winning advertisements (AAs) were selected on the basis of the professional standards that consider creativity as a prerequisite. However, it is unknown if AA is related to satisfactory advertising performance among customers or only to the experts' viewpoints towards the advertisements. This issue in the field of affective engineering and design merits in-depth evaluation. We recruited 30 subjects and performed an electroencephalography (EEG) experiment while watching AAs and non-AAs (NAAs). The event-related potential (ERP) data showed that AAs evoked larger positive potentials 250-1400 [Formula: see text]ms after stimulus onset, particularly in the right fronto-temporal regions. The behavioral results were consistent with the professional recognition given to AAs by experts. The perceived levels of creativity and "product-like" quality were higher for the AAs than for the NAAs. Event-related spectral perturbation (ERSP) analysis further revealed statistically significant differences in the theta, alpha, beta, and gamma band activity in the right fronto-temporal regions between the AAs and NAAs. Our results confirm that EEG features from the time/frequency domains can differentiate affective responses to AAs at a neural circuit level, and provide scientific evidence to support the identification of AAs.

  12. Flight response to spatial and temporal correlates informs risk from wind turbines to the California Condor

    Science.gov (United States)

    Poessel, Sharon; Brandt, Joseph; Mendenhall, Laura C.; Braham, Melissa A.; Lanzone, Michael J.; McGann, Andrew J.; Katzner, Todd

    2018-01-01

    Wind power is a fast-growing energy resource, but wind turbines can kill volant wildlife, and the flight behavior of obligate soaring birds can place them at risk of collision with these structures. We analyzed altitudinal data from GPS telemetry of critically endangered California Condors (Gymnogyps californianus) to assess the circumstances under which their flight behavior may place them at risk from collision with wind turbines. Condor flight behavior was strongly influenced by topography and land cover, and birds flew at lower altitudes and closer to the rotor-swept zone of wind turbines when over ridgelines and steep slopes and over forested and grassland cover types. Condor flight behavior was temporally predictable, and birds flew lower and closer to the rotor-swept zone during early morning and evening hours and during the winter months, when thermal updrafts were weakest. Although condors only occasionally flew at altitudes that placed them in the rotor-swept zone of turbines, they regularly flew near or within wind resource areas preferred by energy developers. Practitioners aiming to mitigate collision risk to this and other soaring bird species of conservation concern can consider the manner in which flight behavior varies temporally and in response to areas of high topographic relief and proximity to nocturnal roosting sites. By contrast, collision risk to large soaring birds from turbines should be relatively lower over flatter and less rugged areas and in habitat used during daytime soaring.

  13. A modified impulse-response representation of the global near-surface air temperature and atmospheric concentration response to carbon dioxide emissions

    Directory of Open Access Journals (Sweden)

    R. J. Millar

    2017-06-01

    Full Text Available Projections of the response to anthropogenic emission scenarios, evaluation of some greenhouse gas metrics, and estimates of the social cost of carbon often require a simple model that links emissions of carbon dioxide (CO2 to atmospheric concentrations and global temperature changes. An essential requirement of such a model is to reproduce typical global surface temperature and atmospheric CO2 responses displayed by more complex Earth system models (ESMs under a range of emission scenarios, as well as an ability to sample the range of ESM response in a transparent, accessible and reproducible form. Here we adapt the simple model of the Intergovernmental Panel on Climate Change 5th Assessment Report (IPCC AR5 to explicitly represent the state dependence of the CO2 airborne fraction. Our adapted model (FAIR reproduces the range of behaviour shown in full and intermediate complexity ESMs under several idealised carbon pulse and exponential concentration increase experiments. We find that the inclusion of a linear increase in 100-year integrated airborne fraction with cumulative carbon uptake and global temperature change substantially improves the representation of the response of the climate system to CO2 on a range of timescales and under a range of experimental designs.

  14. A qualitative investigation of the temporal patterning of the precompetitive anxiety response.

    Science.gov (United States)

    Hanton, Sheldon; Mellalieu, Stephen D; Young, Stuart G

    2002-11-01

    The aim of this study was to examine retrospective perceptions and causal beliefs about temporal experiences of competitive anxiety and related symptoms in the lead up to competition. Qualitative interviews were conducted with 9 elite performers to examine the interaction of intensity, frequency and direction of symptoms associated with competitive anxiety before competition. Data analysis identified six causal networks that supported theoretical predictions suggesting that intensity of cognitive anxiety symptoms remained relatively stable in the lead up to competition, whereas somatic anxiety peaked sharply at the onset of performance. Frequency of anxiety symptoms increased as the competition approached and changes in interpretation of anxiety symptoms were also reported, with self-confidence identified as a moderating variable. The findings highlight the dynamic properties of the stress response and emphasize the need to consider the idiosyncratic nature of the level, frequency and interpretation of performers' precompetitive experiences.

  15. Statistics of “Cold” Early Impulsive Solar Flares in X-Ray and Microwave Domains

    Science.gov (United States)

    Lysenko, Alexandra L.; Altyntsev, Alexander T.; Meshalkina, Natalia S.; Zhdanov, Dmitriy; Fleishman, Gregory D.

    2018-04-01

    Solar flares often happen after a preflare/preheating phase, which is almost or entirely thermal. In contrast, there are the so-called early impulsive flares that do not show a (significant) preflare heating, but instead often show the Neupert effect—a relationship where the impulsive phase is followed by a gradual, cumulative-like, thermal response. This has been interpreted as a dominance of nonthermal energy release at the impulsive phase, even though a similar phenomenology is expected if the thermal and nonthermal energies are released in comparable amounts at the impulsive phase. Nevertheless, some flares do show a good quantitative correspondence between the nonthermal electron energy input and plasma heating; in such cases, the thermal response was weak, which results in them being called “cold” flares. We undertook a systematic search for such events among early impulsive flares registered by the Konus-Wind instrument in the triggered mode from 11/1994 to 4/2017, and selected 27 cold flares based on relationships between hard X-ray (HXR) (Konus-Wind) and soft X-ray (Geostationary Operational Environmental Satellite) emission. For these events, we put together all available microwave data from different instruments. We obtained temporal and spectral parameters of HXR and microwave emissions of the events and examined correlations between them. We found that, compared to a “mean” flare, the cold flares: (i) are weaker, shorter, and harder in the X-ray domain; (ii) are harder and shorter, but not weaker in the microwaves; (iii) have a significantly higher spectral peak frequencies in the microwaves. We discuss the possible physical reasons for these distinctions and implication of the finding.

  16. The relationship between temporal variation of hypoxia, polarographic measurements and predictions of tumour response to radiation

    Science.gov (United States)

    Toma-Dasu, Iuliana; Dasu, Alexandru; Karlsson, Mikael

    2004-10-01

    The polarographic oxygen sensor is one of the most used devices for in vivo measurements of oxygen and many other measurement techniques for measuring tumour hypoxia are correlated with electrode measurements. Little is known however about the relationship between electrode measurements and the real tissue oxygenation. This paper investigates the influence of the temporal change of the hypoxic pattern on the electrode measurements and the tumour response. Electrode measurements and tumour response were simulated using a computer program that allows both the calculation of the tissue oxygenation with respect to the two types of hypoxia that might arise in tumours and the virtual insertion of the electrode into the tissue. It was therefore possible to control the amount of each type of hypoxia in order to investigate their influence on the measurement results. Tissues with several vascular architectures ranging from well oxygenated to poorly oxygenated were taken into consideration as might be seen in practice. The influence of the electrode measurements on the treatment outcome was estimated by calculating the tumour control probability for the tumours characterized either by the real or by the measured tumour oxygenation. We have simulated electrode oxygen measurements in different types of tissues, covering a wide range of tumour oxygenations. The results of the simulations showed that the measured distribution depends on the details of the vascular network and not on the type of hypoxia. We have also simulated the effects of the temporal change of the acute hypoxic pattern due to the opening and the closure of different blood vessels during a full fractionated treatment. The results of this simulation suggested that the temporal variation of the hypoxic pattern does not lead to significantly different results for the electrode measurements or the predicted tumour control probabilities. In conclusion, it was found that the averaging effect of the electrode leads

  17. Temporal dynamic responses of roots in contrasting tomato genotypes to cadmium tolerance.

    Science.gov (United States)

    Borges, Karina Lima Reis; Salvato, Fernanda; Alcântara, Berenice Kussumoto; Nalin, Rafael Storto; Piotto, Fernando Ângelo; Azevedo, Ricardo Antunes

    2018-04-01

    Despite numerous studies on cadmium (Cd) uptake and accumulation in crops, relatively little is available considering the temporal dynamic of Cd uptake and responses to stress focused on the root system. Here we highlighted the responses to Cd-induced stress in roots of two tomato genotypes contrasting in Cd-tolerance: the tolerant Pusa Ruby and the sensitive Calabash Rouge. Tomato genotypes growing in the presence of 35 μM CdCl 2 exhibited a similar trend of Cd accumulation in tissues, mainly in the root system and overall plants exhibited reduction in the dry matter weight. Both genotypes showed similar trends for malondialdehyde and hydrogen peroxide accumulation with increases when exposed to Cd, being this response more pronounced in the sensitive genotype. When the antioxidant machinery is concerned, in the presence of Cd the reduced glutathione content was decreased in roots while ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione S-transferase (GST) activities were increased in the presence of Cd in the tolerant genotype. Altogether these results suggest APX, GR and GST as the main players of the antioxidant machinery against Cd-induced oxidative stress.

  18. Negative temporal summation of the responses to pairs of tone bursts in albino mice inferior colliculus

    Science.gov (United States)

    Bibikov, Nikolay G.; Cai, Chen Qi; Jie, Tang

    2003-10-01

    The extracellular activities of single units in an inferior colliculus of narcotized albino mice have been studied. As a stimuli pairs of best frequency (BF) tone bursts with different duration have been used and forward masking has been studied. The test tone usually has a 40 ms duration at intensity 5 dB above threshold. The intensity and duration of the masker could be changed. It was shown that the forward masking essentially depends upon the duration of the first burst. In many cases, the negative temporal summation can be seen. The increase in the duration of first burst (or masker) leads to the decrease in the whole response. Moreover, the BF tone burst which did not evoke any spike response could inhibit the response to the second (test) tone in some cases. Therefore in many units the inhibitory threshold was lower than the excitatory threshold even at the best frequency. The local application of bicuculline through a multibarrel-electrode increased the pulse activity considerably. However, the effect of forward masking usually left even after an inhibitory antagonist (bicuculline) application. [Work supported by grants 39970251 from NSFC, T010360056 from the Foreign Expert Bureau of the State Council of China, and 02-04-3900 from RFBR-NSFC.

  19. Spectral and Temporal Acoustic Features Modulate Response Irregularities within Primary Auditory Cortex Columns.

    Directory of Open Access Journals (Sweden)

    Andres Carrasco

    Full Text Available Assemblies of vertically connected neurons in the cerebral cortex form information processing units (columns that participate in the distribution and segregation of sensory signals. Despite well-accepted models of columnar architecture, functional mechanisms of inter-laminar communication remain poorly understood. Hence, the purpose of the present investigation was to examine the effects of sensory information features on columnar response properties. Using acute recording techniques, extracellular response activity was collected from the right hemisphere of eight mature cats (felis catus. Recordings were conducted with multichannel electrodes that permitted the simultaneous acquisition of neuronal activity within primary auditory cortex columns. Neuronal responses to simple (pure tones, complex (noise burst and frequency modulated sweeps, and ecologically relevant (con-specific vocalizations acoustic signals were measured. Collectively, the present investigation demonstrates that despite consistencies in neuronal tuning (characteristic frequency, irregularities in discharge activity between neurons of individual A1 columns increase as a function of spectral (signal complexity and temporal (duration acoustic variations.

  20. Population responses in primary auditory cortex simultaneously represent the temporal envelope and periodicity features in natural speech.

    Science.gov (United States)

    Abrams, Daniel A; Nicol, Trent; White-Schwoch, Travis; Zecker, Steven; Kraus, Nina

    2017-05-01

    Speech perception relies on a listener's ability to simultaneously resolve multiple temporal features in the speech signal. Little is known regarding neural mechanisms that enable the simultaneous coding of concurrent temporal features in speech. Here we show that two categories of temporal features in speech, the low-frequency speech envelope and periodicity cues, are processed by distinct neural mechanisms within the same population of cortical neurons. We measured population activity in primary auditory cortex of anesthetized guinea pig in response to three variants of a naturally produced sentence. Results show that the envelope of population responses closely tracks the speech envelope, and this cortical activity more closely reflects wider bandwidths of the speech envelope compared to narrow bands. Additionally, neuronal populations represent the fundamental frequency of speech robustly with phase-locked responses. Importantly, these two temporal features of speech are simultaneously observed within neuronal ensembles in auditory cortex in response to clear, conversation, and compressed speech exemplars. Results show that auditory cortical neurons are adept at simultaneously resolving multiple temporal features in extended speech sentences using discrete coding mechanisms. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Dynamic Properties of Impulse Measuring Systems

    DEFF Research Database (Denmark)

    Pedersen, A.; Lausen, P.

    1971-01-01

    After some basic considerations the dynamic properties of the measuring system are subjected to a general examination based on a number of responses, characteristic of the system. It is demonstrated that an impulse circuit has an internal impedance different from zero, for which reason...

  2. Impulsive parametric damping in energy harvesting

    International Nuclear Information System (INIS)

    Tehrani, Maryam Ghandchi; Pumhoessel, Thomas

    2016-01-01

    In this paper, an electro-mechanical system with a time-varying damper, which is capable of changing the damping coefficient impulsively, is considered. The effect of the impulsive parametric damping to the modal energy content of the mechanical system is investigated analytically as well as numerically. First, the governing differential equation is presented and then the solution of the system's response is obtained through numerical integration. The energy dissipated by the damper is then calculated to investigate the amount of the energy that can be harvested, and the results are compared with the results from a system without parametric impulses. It is shown, that the amount of the harvested energy can be increased by introducing parametric impulses. Then, an analytical formulation is derived for the system using Dirac-Delta impulses and the analytical results are validated with numerical simulations. The device is subjected to an initial condition and therefore is vibrating freely without any base excitation. This could be used for applications such as harvesting energy from the passage of a train, where the train vibration can introduce an initial velocity to the harvester and the energy can then be extracted from the free vibration of the harvester. (paper)

  3. Temporal and ontogenetic variation in the escape response of Ameiva festiva (Squamata, Teiidae

    Directory of Open Access Journals (Sweden)

    Lattanzio

    2014-08-01

    Full Text Available Several factors have been shown to affect lizard escape behavior (flight initiation distance or FID, the distance between predator and prey when the prey initiates escape. Patterns of daily activity, such as foraging or movement behavior, vary with respect to time of day, supporting that escape responses may vary temporally as well. However, there remains scant information regarding the effects of time of day on FID. During peak activity, FID may decrease due to increased cost of giving up resources (e.g., prey or potential mates. An alternative hypothesis is that FID may increase because lizard activity in general may serve to alert a predator in advance of its approach. A lizard in this scenario may be favored to flee sooner rather than later. Moreover, juvenile and adult lizards of multiple species may differ in behavioral, ecological, and morphological traits that could influence escape decisions. I tested the effects of time of day (in 30-min intervals and age (juvenile or adult on the FID of a tropical whiptail lizard, Ameiva festiva in Costa Rica. I found that A. festiva escape responses varied with time of day such that in general, their FID decreased throughout the day. In addition, I observed a peak in FID from mid to late-morning that matches published estimates of peak activity times for A. festiva. Overall, juvenile A. festiva initiated an escape response sooner than adults, which may be related to differences in perceived risk associated with differences in size and predator experience between the two age groups. I conclude that escape responses may be contingent on both the activity level of the animal at the time of approach and its age.

  4. Is premature ejaculation an impulse control disorder?

    Science.gov (United States)

    Ozdemir, Özdemir

    2012-07-01

    Premature ejaculation (PE) is defined as persistent or recurrent ejaculation with minimal sexual stimulation that occurs before the participant wishes to ejaculate and is associated with marked distress or interpersonal difficulty. Impulse control disorders (ICDs) are grouped as a heterogeneous cluster of disorders linked by a "failure to resist" impulses to engage in harmful, disturbing or distressing behaviours. I hypothesise that premature ejaculation is an impulse control disorder. ICDs share features with PE aspects of impaired control, rapid responses to stimuli and hypersensitivity. These disorders often occur with subjective and social distress for patients. In addition to these features, the neurotransmitter systems have been similarly implicated in ICDs and PE. The same treatment options further support a relationship between ICDs and PE. The behaviours likely exist on a spectrum. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Population responses to environmental change in a tropical ant: the interaction of spatial and temporal dynamics.

    Directory of Open Access Journals (Sweden)

    Doug Jackson

    Full Text Available Spatial structure can have a profound, but often underappreciated, effect on the temporal dynamics of ecosystems. Here we report on a counterintuitive increase in the population of a tree-nesting ant, Azteca sericeasur, in response to a drastic reduction in the number of potential nesting sites. This surprising result is comprehensible when viewed in the context of the self-organized spatial dynamics of the ants and their effect on the ants' dispersal-limited natural enemies. Approximately 30% of the trees in the study site, a coffee agroecosystem in southern Mexico, were pruned or felled over a two-year period, and yet the abundance of the ant nests more than doubled over the seven-year study. Throughout the transition, the spatial distribution of the ants maintained a power-law distribution - a signal of spatial self organization - but the local clustering of the nests was reduced post-pruning. A cellular automata model incorporating the changed spatial structure of the ants and the resulting partial escape from antagonists reproduced the observed increase in abundance, highlighting how self-organized spatial dynamics can profoundly influence the responses of ecosystems to perturbations.

  6. Utilizing temporal variations in chemotherapeutic response to improve breast cancer treatment efficacy

    Directory of Open Access Journals (Sweden)

    Daniel J. McGrail

    2015-09-01

    Full Text Available Though survival rates for women with stage I breast cancer have radically improved, treatment options remain poor for the 40% of women diagnosed with later-stage disease. For these patients, improved chemotherapeutic treatment strategies are critical to eradicate any disseminated tumor cells. Despite many promising new drugs in vitro, most ultimately fail in the clinic. One aspect often lost during testing is in vivo circulation half-lives rarely exceed 24 hours, whereas in vitro studies involve drug exposure for 2-3 days. Here, we show how mimicking these exposure times alters efficacy. Next, using this model we show how drug response is highly time-dependent by extending analysis of cell viability out to two weeks. Variations in response both with feeding and time were dependent on drug mechanism of action. Finally, we show that by implementing this temporal knowledge of drug effects to optimize scheduling of drug administration we are able to regain chemosensitivity in a Carboplatin-resistant cell line.

  7. Anxious Individuals Are Impulsive Decision-Makers in the Delay Discounting Task: An ERP Study.

    Science.gov (United States)

    Xia, Lisheng; Gu, Ruolei; Zhang, Dandan; Luo, Yuejia

    2017-01-01

    Impulsivity, which is linked to a wide range of psychiatric disorders, is often characterized by a preference for immediate but smaller rewards over delayed but larger rewards. However, debate exists on the relationship between anxiety and impulsivity. Here we use event-related potential (ERP) components as biomarkers in the temporal discounting task to examine the effect of anxiety on inter-temporal decision-making. Our behavioral results indicated that the high trait anxiety (HTA) group made significantly more immediate choices than the low trait anxiety (LTA) group. Compared with the LTA group, shorter response time was associated with immediate rewards in the HTA group. Furthermore, previous studies have demonstrated three ERP components that are associated with impulsivity and/or delay discounting. First, the N1 is an early sensory component involved in selective attention and attention processing for goal-directed actions. Second, the reward positivity (RewP) reflects reward-related dopaminergic activity and encodes reward values. Third, the P3 is regarded as a measure of motivational significance in the decision-making literature. Accordingly, this study found in the immediate-option-evoked ERPs that the HTA group had a larger N1 than the LTA group did. For the delayed-option-evoked ERPs, the HTA group had larger N1 and RewP for the immediate choice than the LTA group did, while the LTA group had a larger P3 for the delayed choice than the HTA group did. These results support the notion that anxiety individuals are impulsive decision-makers in the Delay Discounting Task.

  8. Temporal responses of coastal hypoxia to nutrient loading and physical controls

    Directory of Open Access Journals (Sweden)

    W. M. Kemp

    2009-12-01

    Full Text Available The incidence and intensity of hypoxic waters in coastal aquatic ecosystems has been expanding in recent decades coincident with eutrophication of the coastal zone. Worldwide, there is strong interest in reducing the size and duration of hypoxia in coastal waters, because hypoxia causes negative effects for many organisms and ecosystem processes. Although strategies to reduce hypoxia by decreasing nutrient loading are predicated on the assumption that this action would reverse eutrophication, recent analyses of historical data from European and North American coastal systems suggest little evidence for simple linear response trajectories. We review published parallel time-series data on hypoxia and loading rates for inorganic nutrients and labile organic matter to analyze trajectories of oxygen (O2 response to nutrient loading. We also assess existing knowledge of physical and ecological factors regulating O2 in coastal marine waters to facilitate analysis of hypoxia responses to reductions in nutrient (and/or organic matter inputs. Of the 24 systems identified where concurrent time series of loading and O2 were available, half displayed relatively clear and direct recoveries following remediation. We explored in detail 5 well-studied systems that have exhibited complex, non-linear responses to variations in loading, including apparent "regime shifts". A summary of these analyses suggests that O2 conditions improved rapidly and linearly in systems where remediation focused on organic inputs from sewage treatment plants, which were the primary drivers of hypoxia. In larger more open systems where diffuse nutrient loads are more important in fueling O2 depletion and where climatic influences are pronounced, responses to remediation tended to follow non-linear trends that may include hysteresis and time-lags. Improved understanding of hypoxia remediation requires that future studies use

  9. Observing painful events in others leads to a temporally extended general response facilitation in the self.

    Science.gov (United States)

    Galang, Carl Michael; Naish, Katherine R; Arbabi, Keon; Obhi, Sukhvinder S

    2017-11-01

    Excitability in the motor cortex is modulated when we observe other people receiving a painful stimulus (Avenanti et al., Nat Neurosci 8(7):955-960, 2005). However, the task dependency of this modulation is not well understood, as different paradigms have yielded seemingly different results. Previous neurophysiological work employing transcranial magnetic stimulation (TMS) suggests that watching another person's hand being pierced by a needle leads to a muscle specific inhibition, assessed via motor evoked potentials. Results from previous behavioural studies suggest that overt behavioural responses are facilitated due to pain observation (Morrison et al., Cereb Cortex 17:2214-2222, 2007b; Morrison et al., Cognition 104:407-416, 2007a). There are several paradigmatic differences both between typical TMS studies and behavioural studies, and within behavioural studies themselves, that limit our overall understanding of how pain observation affects the motor system. In the current study, we combine elements of typical TMS experimental designs in a behavioural assessment of how pain observation affects overt behavioural responding. Specifically, we examined the muscle specificity, timing, and direction of modulation of motor responses due to pain observation. To assess muscle specificity, we employed pain and non-pain videos from previous TMS studies in a Go/No-Go task in which participants responded by either pressing a key with their index finger or with their foot. To assess timing, we examined response times for Go signals presented at 0 or 500 ms after the video. Results indicate that observation of another individual receiving a painful stimulus leads to a non-effector specific, temporally extended response facilitation (e.g., finger and foot facilitation present at 0 and 500 ms delays), compared to observation of non-pain videos. This behavioural facilitation effect differs from the typical motor inhibition seen in TMS studies, and we argue that the effects of

  10. Temporal responses of coastal hypoxia to nutrient loading and physical controls

    Science.gov (United States)

    Kemp, W. M.; Testa, J. M.; Conley, D. J.; Gilbert, D.; Hagy, J. D.

    2009-12-01

    The incidence and intensity of hypoxic waters in coastal aquatic ecosystems has been expanding in recent decades coincident with eutrophication of the coastal zone. Worldwide, there is strong interest in reducing the size and duration of hypoxia in coastal waters, because hypoxia causes negative effects for many organisms and ecosystem processes. Although strategies to reduce hypoxia by decreasing nutrient loading are predicated on the assumption that this action would reverse eutrophication, recent analyses of historical data from European and North American coastal systems suggest little evidence for simple linear response trajectories. We review published parallel time-series data on hypoxia and loading rates for inorganic nutrients and labile organic matter to analyze trajectories of oxygen (O2) response to nutrient loading. We also assess existing knowledge of physical and ecological factors regulating O2 in coastal marine waters to facilitate analysis of hypoxia responses to reductions in nutrient (and/or organic matter) inputs. Of the 24 systems identified where concurrent time series of loading and O2 were available, half displayed relatively clear and direct recoveries following remediation. We explored in detail 5 well-studied systems that have exhibited complex, non-linear responses to variations in loading, including apparent "regime shifts". A summary of these analyses suggests that O2 conditions improved rapidly and linearly in systems where remediation focused on organic inputs from sewage treatment plants, which were the primary drivers of hypoxia. In larger more open systems where diffuse nutrient loads are more important in fueling O2 depletion and where climatic influences are pronounced, responses to remediation tended to follow non-linear trends that may include hysteresis and time-lags. Improved understanding of hypoxia remediation requires that future studies use comparative approaches and consider multiple regulating factors. These analyses

  11. Modulation of auditory evoked responses to spectral and temporal changes by behavioral discrimination training

    Directory of Open Access Journals (Sweden)

    Okamoto Hidehiko

    2009-12-01

    Full Text Available Abstract Background Due to auditory experience, musicians have better auditory expertise than non-musicians. An increased neocortical activity during auditory oddball stimulation was observed in different studies for musicians and for non-musicians after discrimination training. This suggests a modification of synaptic strength among simultaneously active neurons due to the training. We used amplitude-modulated tones (AM presented in an oddball sequence and manipulated their carrier or modulation frequencies. We investigated non-musicians in order to see if behavioral discrimination training could modify the neocortical activity generated by change detection of AM tone attributes (carrier or modulation frequency. Cortical evoked responses like N1 and mismatch negativity (MMN triggered by sound changes were recorded by a whole head magnetoencephalographic system (MEG. We investigated (i how the auditory cortex reacts to pitch difference (in carrier frequency and changes in temporal features (modulation frequency of AM tones and (ii how discrimination training modulates the neuronal activity reflecting the transient auditory responses generated in the auditory cortex. Results The results showed that, additionally to an improvement of the behavioral discrimination performance, discrimination training of carrier frequency changes significantly modulates the MMN and N1 response amplitudes after the training. This process was accompanied by an attention switch to the deviant stimulus after the training procedure identified by the occurrence of a P3a component. In contrast, the training in discrimination of modulation frequency was not sufficient to improve the behavioral discrimination performance and to alternate the cortical response (MMN to the modulation frequency change. The N1 amplitude, however, showed significant increase after and one week after the training. Similar to the training in carrier frequency discrimination, a long lasting

  12. Temporal dynamics of cortical and subcortical responses to apomorphine in Parkinson disease: an H2(15)O PET study

    NARCIS (Netherlands)

    Hosey, Lara A.; Thompson, Jennifer L. W.; Metman, Leonard Verhagen; van den Munckhof, Pepyn; Braun, Allen R.

    2005-01-01

    H2(15)O positron emission tomography (PET) was used to study the temporal course of central nervous system (CNS) responses to apomorphine in patients with idiopathic Parkinson disease (PD). Agonist-induced changes in regional cerebral blood flow (rCBF) were evaluated within

  13. The effects of incidentally learned temporal and spatial predictability on response times and visual fixations during target detection and discrimination.

    Science.gov (United States)

    Beck, Melissa R; Hong, S Lee; van Lamsweerde, Amanda E; Ericson, Justin M

    2014-01-01

    Responses are quicker to predictable stimuli than if the time and place of appearance is uncertain. Studies that manipulate target predictability often involve overt cues to speed up response times. However, less is known about whether individuals will exhibit faster response times when target predictability is embedded within the inter-trial relationships. The current research examined the combined effects of spatial and temporal target predictability on reaction time (RT) and allocation of overt attention in a sustained attention task. Participants responded as quickly as possible to stimuli while their RT and eye movements were measured. Target temporal and spatial predictability were manipulated by altering the number of: 1) different time intervals between a response and the next target; and 2) possible spatial locations of the target. The effects of target predictability on target detection (Experiment 1) and target discrimination (Experiment 2) were tested. For both experiments, shorter RTs as target predictability increased across both space and time were found. In addition, the influences of spatial and temporal target predictability on RT and the overt allocation of attention were task dependent; suggesting that effective orienting of attention relies on both spatial and temporal predictability. These results indicate that stimulus predictability can be increased without overt cues and detected purely through inter-trial relationships over the course of repeated stimulus presentations.

  14. Highly temporally resolved response to seasonal surface melt of the Zachariae and 79N outlet glaciers in Northeast Greenland

    DEFF Research Database (Denmark)

    Rathmann, N. M.; Hvidberg, C. S.; Solgaard, A. M.

    2017-01-01

    The seasonal response to surface melting of the Northeast Greenland Ice Stream outlets, Zachariae and 79N, is investigated using new highly temporally resolved surface velocity maps for 2016 combined with numerical modelling. The seasonal speed-up at 79N of 0.15km/yr is suggested to be driven by ...

  15. The effects of incidentally learned temporal and spatial predictability on response times and visual fixations during target detection and discrimination.

    Directory of Open Access Journals (Sweden)

    Melissa R Beck

    Full Text Available Responses are quicker to predictable stimuli than if the time and place of appearance is uncertain. Studies that manipulate target predictability often involve overt cues to speed up response times. However, less is known about whether individuals will exhibit faster response times when target predictability is embedded within the inter-trial relationships. The current research examined the combined effects of spatial and temporal target predictability on reaction time (RT and allocation of overt attention in a sustained attention task. Participants responded as quickly as possible to stimuli while their RT and eye movements were measured. Target temporal and spatial predictability were manipulated by altering the number of: 1 different time intervals between a response and the next target; and 2 possible spatial locations of the target. The effects of target predictability on target detection (Experiment 1 and target discrimination (Experiment 2 were tested. For both experiments, shorter RTs as target predictability increased across both space and time were found. In addition, the influences of spatial and temporal target predictability on RT and the overt allocation of attention were task dependent; suggesting that effective orienting of attention relies on both spatial and temporal predictability. These results indicate that stimulus predictability can be increased without overt cues and detected purely through inter-trial relationships over the course of repeated stimulus presentations.

  16. Investigation of the temporal humoral immune response in a murine model of actinomycetoma.

    Science.gov (United States)

    Rodríguez, M del C; Torres, J A; Zlotnik, H

    1996-06-01

    The murine model of actinomycetoma offers the potential of studying many unknown aspects of this infection. In this work, the model was used to investigate the temporal humoral immune response to actinomycetoma agents. Groups of 7- to 9-week-old female BALB/c mice were inoculated in one of the hind footpads with one of four different Nocardia strains. To mimic the constant exposure of infected humans to the virulent soil inhabiting agents, a second injection consisting of live nocardiae in incomplete Freund's adjuvant was administered five months after the first one. Murine serum samples were collected throughout the study and their IgM and IgM titers were determined by ELISA and the Western blot assay. The results obtained indicate that the ELISA titers increased as the infection progressed and this correlated with a greater number of antigen bands being recognized in the blots. Overall, however, the ELISA titers were lower for the N. brasiliensis infected mice than those of the N. asteroides ones. This observation may be indicative of an immunosuppressive state and is worthy of further investigation.

  17. Contributions of nonlinear fluxes to the temporal response of fluid plasma

    Science.gov (United States)

    Min, Byunghoon; An, Chan-Yong; Kim, Chang-Bae

    2015-09-01

    Nonlinear energy fluxes are known to redistribute energy according to detailed conservation laws. In addition, the temporal response of plasma is altered by the linear reaction due to the nonlinear fluxes that are not involved in the transport of the energy. Simulations for three cases of the adiabaticity parameter α =0.1 , 1.0 and 10.0 are performed in relation to the Hasegawa-Wakatani model and the frequency alterations are found to be notable for k{ρ\\text{s}}\\gt0.5 where k is the Fourier scale and {ρ\\text{s}} is the ion gyro-radius computed at the electron temperature. The levels of the density fluctuation {{n}{k}} and the potential {{\\varphi}{k}} get closer to each other as α increases and they are equal for α =10 . Yet, the frequencies are still discernible for α =10.0 . Non-transporting fluxes (NTFs) turned out to be anisotropic because the phase difference {δ{k}} between {{n}{k}} and {{\\varphi}{k}} has symmetry so that \\text{cos}{δ{k}} is isotropic in the Fourier space while \\text{sin}{δ{k}} is odd in k y . The NTF of the energy is approximated to be proportional to the gradient of the energy in the y direction of the Fourier space with the proportionality coefficient being dimensionally advecting velocity.

  18. Temporal responses of peak citrus flowering to climate change in Iran: 1960-2010

    Science.gov (United States)

    Fitchett, Jennifer; Grab, Stefan; Thompson, Dave; Roshan, GholamReza

    2014-05-01

    Recent studies investigating floral and faunal phenological responses to climate change have highlighted the extent to which these relationships are species and location specific. This study investigates temporal responses of citrus peak flowering to climate change in the cities of Kerman, Shiraz and Gorgan, Iran. Phenological data comprise peak flowering dates of five citrus types: orange (Citrus x sinensis), tangerine (Citrus x tangerine), sweet lemon (Citrus limetta), sour lemon (Citrus x limon) and sour orange (Citrus x aurantium). These were collected daily from government heritage gardens located within each of the three cities, and archived by a private Iranian company, for the period 1960-2010. For the same period, daily Tmax, Tmin, rainfall and sunshine hour data were acquired from the Iranian Meteorological Organization. Time trend analyses were undertaken for both the phenological and meteorological data, followed by linear regression to determine the nature and extent of any relationships between these variables. We find that the mean peak flowering dates, and their long-term trends over the 51-year period, are very similar amongst the five citrus types within each city, but demonstrate significant differences between cities. Flowering date advances of 0.12-0.17d/yr are recorded for Kerman, and more rapid advances of 0.56-0.65d/yr for Shiraz. Notable progressive delays in flowering dates occur in Gorgan (0.05-0.1d/yr). The peak flowering dates of citrus in the former two cities demonstrate strong relationships with mean annual Tmin, ranging from r = 0.46-0.61 (p = 0002; p international markets.

  19. Seedling establishment and physiological responses to temporal and spatial soil moisture changes

    Science.gov (United States)

    Jeremy Pinto; John D. Marshall; Kas Dumroese; Anthony S. Davis; Douglas R. Cobos

    2016-01-01

    In many forests of the world, the summer season (temporal element) brings drought conditions causing low soil moisture in the upper soil profile (spatial element) - a potentially large barrier to seedling establishment. We evaluated the relationship between initial seedling root depth, temporal and spatial changes in soil moisture during drought after...

  20. Functional impulsivity and reinforcement sensitivity theory.

    Science.gov (United States)

    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.

  1. Spatio-temporal changes of photosynthesis in carnivorous plants in response to prey capture, retention and digestion.

    Science.gov (United States)

    Pavlovič, Andrej

    2010-11-01

    Carnivorous plants have evolved modified leaves into the traps which assist in nutrient uptake from captured prey. It is known that the traps of carnivorous plants have usually lower photosynthetic rates than assimilation leaves as a result of adaptation to carnivory. However a few recent studies have indicated that photosynthesis and respiration undergo spatio-temporal changes during prey capture and retention, especially in the genera with active trapping mechanisms. This study describes the spatio-temporal changes of effective quantum yield of photochemical energy conversion in photosystem II (Ф PSII) in response to ant-derived formic acid during its capture and digestion.

  2. Temporal, but not Directional, Prior Knowledge Shortens Muscle Reflex Latency in Response to Sudden Transition of Support Surface During Walking

    Science.gov (United States)

    Shinya, Masahiro; Kawashima, Noritaka; Nakazawa, Kimitaka

    2016-01-01

    The central nervous system takes advantage of prior knowledge about potential upcoming perturbations for modulating postural reflexes. There are two distinct aspects of prior knowledge: spatial and temporal. This study investigated how each of spatial and temporal prior knowledge contributes to the shortening of muscle response latency. Eleven participants walked on a split-belt treadmill and perturbed by sudden acceleration or deceleration of the right belt at right foot contact. Spatial prior knowledge was given by instruction of possible direction (e.g., only acceleration) of upcoming perturbation at the beginning of an experimental session. Temporal prior knowledge was given to subjects by warning tones at foot contact during three consecutive strides before the perturbation. In response to acceleration perturbation, reflexive muscle activity was observed in soleus (SOL) and gastrocnemius (GAS) muscles. Onset latency of the GAS response was shorter (72 ms vs. 58 ms) when subjects knew the timing of the upcoming perturbation, whereas the latency was independent of directional prior knowledge. SOL onset latency (44 ms) was not influenced by directional nor temporal prior knowledge. Although spinal neural circuit that mediates short-latency reflex was not influenced by the prior knowledge, excitability in supra-spinal neural circuit that mediates medium- and long-latency reflex might be enhanced by knowing the timing of the upcoming perturbation. PMID:26903838

  3. Impulse pumping modelling and simulation

    International Nuclear Information System (INIS)

    Pierre, B; Gudmundsson, J S

    2010-01-01

    Impulse pumping is a new pumping method based on propagation of pressure waves. Of particular interest is the application of impulse pumping to artificial lift situations, where fluid is transported from wellbore to wellhead using pressure waves generated at wellhead. The motor driven element of an impulse pumping apparatus is therefore located at wellhead and can be separated from the flowline. Thus operation and maintenance of an impulse pump are facilitated. The paper describes the different elements of an impulse pumping apparatus, reviews the physical principles and details the modelling of the novel pumping method. Results from numerical simulations of propagation of pressure waves in water-filled pipelines are then presented for illustrating impulse pumping physical principles, and validating the described modelling with experimental data.

  4. Response of bacterioplankton communities to cadmium exposure in coastal water microcosms with high temporal variability.

    Science.gov (United States)

    Wang, Kai; Zhang, Demin; Xiong, Jinbo; Chen, Xinxin; Zheng, Jialai; Hu, Changju; Yang, Yina; Zhu, Jianlin

    2015-01-01

    Multiple anthropogenic disturbances to bacterial diversity have been investigated in coastal ecosystems, in which temporal variability in the bacterioplankton community has been considered a ubiquitous process. However, far less is known about the temporal dynamics of a bacterioplankton community responding to pollution disturbances such as toxic metals. We used coastal water microcosms perturbed with 0, 10, 100, and 1,000 μg liter(-1) of cadmium (Cd) for 2 weeks to investigate temporal variability, Cd-induced patterns, and their interaction in the coastal bacterioplankton community and to reveal whether the bacterial community structure would reflect the Cd gradient in a temporally varying system. Our results showed that the bacterioplankton community structure shifted along the Cd gradient consistently after a 4-day incubation, although it exhibited some resistance to Cd at low concentration (10 μg liter(-1)). A process akin to an arms race between temporal variability and Cd exposure was observed, and the temporal variability overwhelmed Cd-induced patterns in the bacterial community. The temporal succession of the bacterial community was correlated with pH, dissolved oxygen, NO3 (-)-N, NO2 (-)-N, PO4 (3-)-P, dissolved organic carbon, and chlorophyll a, and each of these parameters contributed more to community variance than Cd did. However, elevated Cd levels did decrease the temporal turnover rate of community. Furthermore, key taxa, affiliated to the families Flavobacteriaceae, Rhodobacteraceae, Erythrobacteraceae, Piscirickettsiaceae, and Alteromonadaceae, showed a high frequency of being associated with Cd levels during 2 weeks. This study provides direct evidence that specific Cd-induced patterns in bacterioplankton communities exist in highly varying manipulated coastal systems. Future investigations on an ecosystem scale across longer temporal scales are needed to validate the observed pattern. Copyright © 2015, American Society for Microbiology. All

  5. Anxious Individuals Are Impulsive Decision-Makers in the Delay Discounting Task: An ERP Study

    OpenAIRE

    Xia, Lisheng; Gu, Ruolei; Zhang, Dandan; Luo, Yuejia

    2017-01-01

    Impulsivity, which is linked to a wide range of psychiatric disorders, is often characterized by a preference for immediate but smaller rewards over delayed but larger rewards. However, debate exists on the relationship between anxiety and impulsivity. Here we use event-related potential (ERP) components as biomarkers in the temporal discounting task to examine the effect of anxiety on inter-temporal decision-making. Our behavioral results indicated that the high trait anxiety (HTA) group mad...

  6. Impulse and Movement Space-Time Variability.

    Science.gov (United States)

    Kim, Seonjin; Carlton, Les G.; Liu, Yeou-Teh; Newell, Karl M.

    1999-12-01

    In 3 experiments, the authors examined movement space-time variability as a function of the force-time properties of the initial impulse in a movement timing task. In the range of motion and movement time task conditions, peak force, initial rate of force, and force duration were manipulated either independently or in combination across a range of parameter values. The findings showed that (a) impulse variability is predicted well by the elaboration of the isometric force variability scaling functions of L. G. Carlton, K. H. Kim, Y. T. Liu, and K. M. Newell (1993) to movement, and (b) the movement spatial and temporal outcome variability are complementary and well predicted by an equation treating the variance of force and time in Newton's 2nd law as independent random variables. Collectively, the findings suggest that movement outcome variability is the product of a coherent space-time function that is driven by the nonlinear scaling of the force-time properties of the initial impulse.

  7. Temporal Feasibility of Rapid Joint Inversions in Response to Tsunamis Triggered by Megathrust Earthquakes

    Science.gov (United States)

    Williamson, A.; Newman, A. V.

    2014-12-01

    Joint inversions of sub-areal surface deformation and tsunami waves generated by seafloor ground motions, while still in their infancy, have the opportunity for realistic representations of megathrust earthquake slip responsible, which occurs primarily offshore. Such joint inversions, including Gusman, et al. [JGR, 2010] and Wei et al. [PAGEOPH, 2014], highlight fault slip unobservable with on land measurements alone. Careful detection of possible slip patterns can affect how nearby communities prepare for future events, therefore their discovery is important for hazard mitigation. Joint inversions could also prove invaluable during a large even through a rapid inversion of real time data. This study looks at the availability and accessibility of land-based GPS and deep-ocean pressure sensor data for rapid join inversions, and the latency between such solutions and both local and global tsunami wave arrivals. We consider GPS rather than other ground-based deformation techniques because of its ability to provide rapid and continuous translations of the ground surface. For tsunami observations, we focus on deep-ocean pressure sensors such as those used in DART systems, because of similarly rapid and continues data availability. Similarly tsunami waves traveling through the deep-ocean have negligible non-linear components, making them ideal for inversion methods. We create a source event in a zone with an elevated seismic risk and then track tsunami travel times to the coast and the nearest deep-ocean pressure sensors to determine a temporal limit to warnings that can be issued to nearby regions. By assessing this latency, focus can be given to areas where an inversion of this type has the potential to improve warning information. This study also identifies regions that lack necessary on and offshore instrumentation to warn coastal communities at risk for tsunamigenic earthquakes. By assessing the feasibility of joint inversions, it becomes easier to move forward with

  8. The metabolic and temporal basis of muscle hypertrophy in response to resistance exercise.

    Science.gov (United States)

    Brook, Matthew S; Wilkinson, Daniel J; Smith, Kenneth; Atherton, Philip J

    2016-09-01

    Constituting ∼40% of body mass, skeletal muscle has essential locomotory and metabolic functions. As such, an insight into the control of muscle mass is of great importance for maintaining health and quality-of-life into older age, under conditions of cachectic disease and with rehabilitation. In healthy weight-bearing individuals, muscle mass is maintained by the equilibrium between muscle protein synthesis (MPS) and muscle protein breakdown; when this balance tips in favour of MPS hypertrophy occurs. Despite considerable research into pharmacological/nutraceutical interventions, resistance exercise training (RE-T) remains the most potent stimulator of MPS and hypertrophy (in the majority of individuals). However, the mechanism(s) and time course of hypertrophic responses to RE-T remain poorly understood. We would suggest that available data are very much in favour of the notion that the majority of hypertrophy occurs in the early phases of RE-T (though still controversial to some) and that, for the most part, continued gains are hard to come by. Whilst the mechanisms of muscle hypertrophy represent the culmination of mechanical, auto/paracrine and endocrine events, the measurement of MPS remains a cornerstone for understanding the control of hypertrophy - mainly because it is the underlying driving force behind skeletal muscle hypertrophy. Development of sophisticated isotopic techniques (i.e. deuterium oxide) that lend to longer term insight into the control of hypertrophy by sustained RE-T will be paramount in providing insights into the metabolic and temporal regulation of hypertrophy. Such technologies will have broad application in muscle mass intervention for both athletes and for mitigating disease/age-related cachexia and sarcopenia, alike.

  9. Temporal and Spatial Evolution of Precipitation in Response to the Growth of Taiwan Topography

    Science.gov (United States)

    Insel, N.; Lee, S.

    2015-12-01

    Taiwan is known as one of the best field areas to study the interactions between tectonics, climate and surface processes. One of the main feedback components is the tendency of topography to increase orographically localized precipitation, but it is unclear how climate may have changed over time as Taiwan topography developed. We present results from two regional general circulation models (RegCM4, REMO) to evaluate dynamical and physical atmospheric changes associated with variations in the height of the Taiwanese Central Range. A series of experiments are conducted with topography systematically varying between 0 and 100% of the modern. To best reproduce the Taiwanese topography, our experiments are performed with a horizontal resolution of 10-20km. Our current simulations focus on the understanding of the temporal and spatial evolution of climate in response to surface uplift. Our first objective is to assess the ability of the regional models to simulate modern climate over Taiwan. An initial comparison between simulated and observed data indicates that the limited-domain models perform very well in capturing the spatial precipitation pattern over Taiwan. Simulated high precipitation occurs along the Central Range with maximum annual precipitation in the northeast. Decreasing precipitation rates towards to west and southwest can be observed in model and observational data. Models with spatial resolutions of 50km or more are not capable to reproduce the observed pattern. Our second objective is to investigate the effect of Pliocene growth of the Central Range on regional climate over Taiwan. Preliminary model results indicate that precipitation over Taiwan strongly correlates with topography. Reducing the topography in our model domain results in a significant decrease in precipitation across the entire island. Our goal is to evaluate the climate sensitivity to a range of mountain topographies and quantify threshold elevations needed to induce the modern

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

    Science.gov (United States)

    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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Spatial and temporal variability of rainfall and their effects on hydrological response in urban areas – a review

    Directory of Open Access Journals (Sweden)

    E. Cristiano

    2017-07-01

    Full Text Available In urban areas, hydrological processes are characterized by high variability in space and time, making them sensitive to small-scale temporal and spatial rainfall variability. In the last decades new instruments, techniques, and methods have been developed to capture rainfall and hydrological processes at high resolution. Weather radars have been introduced to estimate high spatial and temporal rainfall variability. At the same time, new models have been proposed to reproduce hydrological response, based on small-scale representation of urban catchment spatial variability. Despite these efforts, interactions between rainfall variability, catchment heterogeneity, and hydrological response remain poorly understood. This paper presents a review of our current understanding of hydrological processes in urban environments as reported in the literature, focusing on their spatial and temporal variability aspects. We review recent findings on the effects of rainfall variability on hydrological response and identify gaps where knowledge needs to be further developed to improve our understanding of and capability to predict urban hydrological response.

  12. Dopa therapy and action impulsivity: subthreshold error activation and suppression in Parkinson's disease.

    Science.gov (United States)

    Fluchère, Frédérique; Deveaux, Manon; Burle, Borís; Vidal, Franck; van den Wildenberg, Wery P M; Witjas, Tatiana; Eusebio, Alexandre; Azulay, Jean-Philippe; Hasbroucq, Thierry

    2015-05-01

    Impulsive actions entail (1) capture of the motor system by an action impulse, which is an urge to act and (2) failed suppression of that impulse in order to prevent a response error. Several studies indicate that dopaminergic treatment can induce action impulsivity in patients diagnosed with Parkinson's disease (PD). Whether this effect is due to increased impulse expression or to decreased impulse suppression remains to be deciphered. We used a novel approach based on electromyographic (EMG) analyses to decipher the effects of the patient's usual dopaminergic therapy on the expression and suppression of subliminal erroneous impulses. To this end, we used a within-subject design and took advantage of the Simon task, that elicits prepotent response tendencies. The patients (N = 15) performed the task on their usual dopaminergic medication and after complete medication withdrawal (for at least 12 h). The correction rate that measures the ability to suppress subthreshold impulsive muscle activity was lower when the patients were on medication as compared to their off medication state (p < 0.05). The incorrect activation rate that measures the capture of the motor system by action impulses was unaffected by medication. Dopa therapy affected action impulsivity. Although medication did not influence the incidence of fast action impulses, it significantly reduced patients' ability to abort and suppress muscle activation related to the incorrect response alternative.

  13. IMPULSIVITY PARAMETER FOR SOLAR FLARES

    Energy Technology Data Exchange (ETDEWEB)

    Fajardo-Mendieta, W. G.; Alvarado-Gómez, J. D.; Calvo-Mozo, B. [Observatorio Astronómico Nacional, Universidad Nacional de Colombia, Bogotá (Colombia); Martinez-Oliveros, J. C., E-mail: wgfajardom@unal.edu.co, E-mail: bcalvom@unal.edu.co, E-mail: oliveros@ssl.berkeley.edu, E-mail: jalvarad@eso.org [Space Sciences Laboratory, UC Berkeley, Berkeley, CA 94720 (United States)

    2016-02-10

    Three phases are typically observed during solar flares: the preflare, impulsive, and decay phases. During the impulsive phase, it is believed that the electrons and other particles are accelerated after the stored energy in the magnetic field is released by reconnection. The impulsivity of a solar flare is a quantifiable property that shows how quickly this initial energy release occurs. It is measured via the impulsivity parameter, which we define as the inverse of the overall duration of the impulsive phase. We take the latter as the raw width of the most prominent nonthermal emission of the flare. We computed this observable over a work sample of 48 M-class events that occurred during the current Solar Cycle 24 by using three different methods. The first method takes into account all of the nonthermal flare emission and gives very accurate results, while the other two just cover fixed energy intervals (30–40 keV and 25–50 keV) and are useful for fast calculations. We propose an alternative way to classify solar flares according to their impulsivity parameter values, defining three different types of impulsivity, namely, high, medium, and low. This system of classification is independent of the manner used to calculated the impulsivity parameter. Lastly, we show the relevance of this tool as a discriminator of different HXR generation processes.

  14. Understanding the Spatio-Temporal Response of Coral Reef Fish Communities to Natural Disturbances: Insights from Beta-Diversity Decomposition.

    Science.gov (United States)

    Lamy, Thomas; Legendre, Pierre; Chancerelle, Yannick; Siu, Gilles; Claudet, Joachim

    2015-01-01

    Understanding how communities respond to natural disturbances is fundamental to assess the mechanisms of ecosystem resistance and resilience. However, ecosystem responses to natural disturbances are rarely monitored both through space and time, while the factors promoting ecosystem stability act at various temporal and spatial scales. Hence, assessing both the spatial and temporal variations in species composition is important to comprehensively explore the effects of natural disturbances. Here, we suggest a framework to better scrutinize the mechanisms underlying community responses to disturbances through both time and space. Our analytical approach is based on beta diversity decomposition into two components, replacement and biomass difference. We illustrate this approach using a 9-year monitoring of coral reef fish communities off Moorea Island (French Polynesia), which encompassed two severe natural disturbances: a crown-of-thorns starfish outbreak and a hurricane. These disturbances triggered a fast logistic decline in coral cover, which suffered a 90% decrease on all reefs. However, we found that the coral reef fish composition remained largely stable through time and space whereas compensatory changes in biomass among species were responsible for most of the temporal fluctuations, as outlined by the overall high contribution of the replacement component to total beta diversity. This suggests that, despite the severity of the two disturbances, fish communities exhibited high resistance and the ability to reorganize their compositions to maintain the same level of total community biomass as before the disturbances. We further investigated the spatial congruence of this pattern and showed that temporal dynamics involved different species across sites; yet, herbivores controlling the proliferation of algae that compete with coral communities were consistently favored. These results suggest that compensatory changes in biomass among species and spatial

  15. [Kleptomania: an irresistible impulse].

    Science.gov (United States)

    Hatzigeorgiou, K

    2011-01-01

    This review presents the historical-epidemiological and clinical aspects of Kleptomania. The diagnostic criteria, on the basis of which it is categorized in the group of Impulse Control Disorders, are defined precisely. All the aspects of its causative pathogenesis are deeply analyzed, as they are projected through its phenomenological, psychoanalytical and psycho-biological approach. Particular emphasis is given on its differential diagnosis from other psycho-pathological conditions and especially from the co-morbidities that often accompany it. The frame of treatment is established and its course and the final outcome are analyzed. Finally, it is determined what should be the objectives of future research, which will contribute decisively to the ascertainment of the exact incidence of Kleptomania in the general population, to the clarification of its causative pathogenesis and especially to the most effective treatment of this serious mental disorder.

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

    Science.gov (United States)

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

    2017-09-01

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

  17. Recent Insights into the Neurobiology of Impulsivity

    Science.gov (United States)

    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

  18. Generation of ultra-intense and ultra-short laser pulses with high temporal contrast; Generation d'impulsions laser ultra-breves et ultra-intenses a contraste temporel eleve

    Energy Technology Data Exchange (ETDEWEB)

    Julien, A

    2006-03-15

    The topic of this thesis work concerns the design and the characterization of an efficient device devoted to the temporal contrast improvement for ultra-intense femtosecond laser pulses. The contrast is defined as the intensity ratio between the main femtosecond pulse and its nanosecond pedestal. This pedestal is the amplified spontaneous emission (ASE), inherent with laser amplification mechanism. The ASE background has dramatic effects for laser-matter interactions on a solid target. The presented work consists in the theoretical and experimental study of a temporal filter based on a third order nonlinear effect acting on the pulse polarization. We have studied several kinds of nonlinear filters. The selected device is based on the process of cross-polarized wave generation (XPW) in crystals with an anisotropic third-order nonlinear susceptibility. This nonlinear filter has been experimented on various femtosecond systems. It allows a contrast improvement of several orders of magnitude, as demonstrated by temporal profiles measurements on a large intensity dynamic. A device to improve the nonlinear process conversion efficiency, it means the filter transmission, has also been achieved. This method is based on constructive interferences between XPW signals generated in different crystals. This setup has made it possible to reach experimentally the maximum theoretical efficiency ( >20%) and in the same time ensures the system stability. At least, we have demonstrated that the filter preserves, or even improves, spectral and spatial qualities of the laser pulse. These results are thus particularly promising and allow contemplating the implementation of the filter in current femtosecond systems. (author)

  19. Response of human epileptic temporal lobe cortical blood flow to hyperventilation.

    Science.gov (United States)

    Weinand, M E; Carter, L P; Oommen, K J; Hutzler, R; Labiner, D M; Talwar, D; el-Saadany, W; Ahern, G L

    1995-07-01

    Bilateral long-term surface cortical cerebral blood flow (CBF) and electrocorticographic (ECoG) monitoring were performed in eight patients with complex partial seizures. In each patient, the epileptic temporal lobe was localized using ictal ECoG. Mean seizure interval (frequency-1) off anticonvulsant medication, a clinical measure of epileptogenicity, was 1.0 +/- 0.3 h (range: 0.4 to 2.5 h). During 13 interictal hyperventilation periods, 3.6 +/- 0.6 min in duration, the mean decrease in epileptic and nonepileptic temporal cortical CBF was 13.7 +/- 2.3 versus 6.4 +/- 1.9 ml/(100 g min) (t = 2.230, d.f. = 16, P e. frequency increased) with increasing magnitude of seizure focus CBF reduction during hyperventilation. Seizure interval was significantly correlated with epileptic temporal lobe CBF decrease during hyperventilation (R = 0.763, d.f. = 5, P < 0.05). The data suggest that, compared to nonepileptic brain, epileptic temporal lobe is particularly prone to hypoperfusion during hyperventilation. Epileptogenicity is a function of this seizure focus susceptibility to ischemia. The finding of abnormal seizure focus autoregulation during hyperventilation has implication for epileptic focus localization with cerebral blood flow analysis.

  20. BOLD Response to Motion Verbs in Left Posterior Middle Temporal Gyrus during Story Comprehension

    Science.gov (United States)

    Wallentin, Mikkel; Nielsen, Andreas Hojlund; Vuust, Peter; Dohn, Anders; Roepstorff, Andreas; Lund, Torben Ellegaard

    2011-01-01

    A primary focus within neuroimaging research on language comprehension is on the distribution of semantic knowledge in the brain. Studies have shown that the left posterior middle temporal gyrus (LPMT), a region just anterior to area MT/V5, is important for the processing of complex action knowledge. It has also been found that motion verbs cause…

  1. BOLD response to motion verbs in left posterior middle temporal gyrus during story comprehension

    DEFF Research Database (Denmark)

    Wallentin, Mikkel; Nielsen, Andreas Højlund; Vuust, Peter

    2011-01-01

    A primary focus within neuroimaging research on language comprehension is on the distribution of semantic knowledge in the brain. Studies have shown that the left posterior middle temporal gyrus (LPMT), a region just anterior to area MT/V5, is important for the processing of complex action...

  2. Superior Temporal Activation in Response to Dynamic Audio-Visual Emotional Cues

    Science.gov (United States)

    Robins, Diana L.; Hunyadi, Elinora; Schultz, Robert T.

    2009-01-01

    Perception of emotion is critical for successful social interaction, yet the neural mechanisms underlying the perception of dynamic, audio-visual emotional cues are poorly understood. Evidence from language and sensory paradigms suggests that the superior temporal sulcus and gyrus (STS/STG) play a key role in the integration of auditory and visual…

  3. Ultrasound Doppler but not temporal summation of pain predicts DAS28 response in rheumatoid arthritis

    DEFF Research Database (Denmark)

    Christensen, Anton Wulf; Rifbjerg-Madsen, Signe; Christensen, Robin

    2016-01-01

    OBJECTIVE: Previous studies have suggested a link between inflammation and central sensitization of pain in patients with RA. We conducted a prospective cohort study to determine whether US Doppler (USD), temporal summation (TS) of pain-assessed at baseline-and the potential interaction between...

  4. Negative emotion-driven impulsivity predicts substance dependence problems.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Nakamura, K; Kurasawa, M; Shirane, M

    2000-04-17

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

  6. Bifurcation Analysis and Application for Impulsive Systems with Delayed Impulses

    Science.gov (United States)

    Church, Kevin E. M.; Liu, Xinzhi

    In this article, we present a systematic approach to bifurcation analysis of impulsive systems with autonomous or periodic right-hand sides that may exhibit delayed impulse terms. Methods include Lyapunov-Schmidt reduction and center manifold reduction. Both methods are presented abstractly in the context of the stroboscopic map associated to a given impulsive system, and are illustrated by way of two in-depth examples: the analysis of a SIR model of disease transmission with seasonality and unevenly distributed moments of treatment, and a scalar logistic differential equation with a delayed census impulsive harvesting effort. It is proven that in some special cases, the logistic equation can exhibit a codimension two bifurcation at a 1:1 resonance point.

  7. Relations between perceptual measures of temporal processing, auditory-evoked brainstem responses and speech intelligibility in noise

    DEFF Research Database (Denmark)

    Papakonstantinou, Alexandra; Strelcyk, Olaf; Dau, Torsten

    2011-01-01

    This study investigates behavioural and objective measures of temporal auditory processing and their relation to the ability to understand speech in noise. The experiments were carried out on a homogeneous group of seven hearing-impaired listeners with normal sensitivity at low frequencies (up to 1...... kHz) and steeply sloping hearing losses above 1 kHz. For comparison, data were also collected for five normalhearing listeners. Temporal processing was addressed at low frequencies by means of psychoacoustical frequency discrimination, binaural masked detection and amplitude modulation (AM......) detection. In addition, auditory brainstem responses (ABRs) to clicks and broadband rising chirps were recorded. Furthermore, speech reception thresholds (SRTs) were determined for Danish sentences in speechshaped noise. The main findings were: (1) SRTs were neither correlated with hearing sensitivity...

  8. Opposing Subjective Temporal Experiences in Response to Unpredictable and Predictable Fear-Relevant Stimuli

    Directory of Open Access Journals (Sweden)

    Qian Cui

    2018-03-01

    Full Text Available Previous studies have found that the durations of fear-relevant stimuli were overestimated compared to those of neutral stimuli, even when the fear-relevant stimuli were only anticipated. The current study aimed to investigate the effect of the predictability of fear-relevant stimuli on sub-second temporal estimations. In Experiments 1a and 1b, a randomized design was employed to render the emotional valence of each trial unpredictable. In Experiments 2a and 2b, we incorporated a block design and a cueing paradigm, respectively, to render the emotional stimuli predictable. Compared with the neutral condition, the estimated blank interval was judged as being shorter under the unpredictable fear-relevant condition, while it was judged as being longer under the predictable fear-relevant condition. In other words, the unpredictable and predictable fear-relevant stimuli led to opposing temporal distortions. These results demonstrated that emotions modulate interval perception during different time processing stages.

  9. Temporal properties of network-mediated responses to repetitive stimuli are dependent upon retinal ganglion cell type

    Science.gov (United States)

    Im, Maesoon; Fried, Shelley I.

    2016-04-01

    Objective. To provide artificially-elicited vision that is temporally dynamic, retinal prosthetic devices will need to repeatedly stimulate retinal neurons. However, given the diversity of physiological types of retinal ganglion cells (RGCs) as well as the heterogeneity of their responses to electric stimulation, temporal properties of RGC responses have not been adequately investigated. Here, we explored the cell type dependence of network-mediated RGC responses to repetitive electric stimulation at various stimulation rates. Approach. We examined responses of ON and OFF types of RGCs in the rabbit retinal explant to five consecutive stimuli with varying inter-stimulus intervals (10-1000 ms). Each stimulus was a 4 ms long monophasic sinusoidal cathodal current, which was applied epiretinally via a conical electrode. Spiking activity of targeted RGCs was recorded using a cell-attached patch electrode. Main results. ON and OFF cells had distinct responses to repetitive stimuli. Consistent with earlier studies, OFF cells always generated reduced responses to subsequent stimuli compared to responses to the first stimulus. In contrast, a new stimulus to ON cells suppressed all pending/ongoing responses from previous stimuli and initiated its own response that was remarkably similar to the response from a single stimulus in isolation. This previously unreported ‘reset’ behavior was observed exclusively and consistently in ON cells. These contrasts between ON and OFF cells created a range of stimulation rates (4-7 Hz) that maximized the ratio of the responses arising in ON versus OFF cells. Significance. Previous clinical testing reported that subjects perceive bright phosphenes (ON responses) and also prefer stimulation rates of 5-7 Hz. Our results suggest that responses of ON cells are weak at high rates of stimulation (> ˜7 Hz) due to the reset while responses of OFF cells are strong at low rates (cells more closely match physiological patterns (Im and Fried 2015

  10. The effects of lighting conditions on responses of cells selective for face views in the macaque temporal cortex.

    Science.gov (United States)

    Hietanen, J K; Perrett, D I; Oram, M W; Benson, P J; Dittrich, W H

    1992-01-01

    Neural mechanisms underlying recognition of objects must overcome the changes in an object's appearance caused by inconsistent viewing conditions, particularly those that occur with changes in lighting. In humans, lesions to the posterior visual association cortex can impair the ability to recognize objects and faces across different lighting conditions. Inferotemporal lesions in monkey have been shown to produce a similar difficulty in object matching tasks. Here we report on the extent to which cell responses selective for the face and other views of the head in monkey temporal cortex tolerate changes in lighting. For each cell studied the (preferred) head view eliciting maximal response was first established under normal lighting. Cells were then tested with the preferred head view lit from different directions (i.e. front, above, below or from the side). Responses of some cells failed to show complete generalization across all lighting conditions but together as a "population" they responded equally strongly under all four lighting conditions. Further tests on sub-groups of cells revealed that stimulus selectivity was maintained despite unusual lighting. The cells discriminated between head and control stimuli and between different views of the head independent of the lighting direction. The results indicate that constancy of recognition across different lighting conditions is apparent in the responses of single cells in the temporal cortex. Lighting constancy appears to be established by matching the retinal image to view-specific descriptions of objects (i.e. neurons which compute object structure from a limited range of perspective views).

  11. The Adolescent Coping Process Interview: Measuring Temporal and Affective Components of Adolescent Responses to Peer Stress

    OpenAIRE

    Gould, Laura Feagans; Hussong, Andrea M.; Keeley, Mary L.

    2007-01-01

    The way in which adolescents cope with stressors in their lives has been established as an important correlate of adjustment. While most theoretical models of coping entail unfolding transactions between coping strategies and emotional arousal, the majority of coping measures tap only trait-level coping styles, ignoring both temporal and affective components of the coping process. The current study fills this gap by establishing the psychometric properties of a newly developed measure, the Ad...

  12. A Prediction Algorithm for Drug Response in Patients with Mesial Temporal Lobe Epilepsy Based on Clinical and Genetic Information.

    Science.gov (United States)

    Silva-Alves, Mariana S; Secolin, Rodrigo; Carvalho, Benilton S; Yasuda, Clarissa L; Bilevicius, Elizabeth; Alvim, Marina K M; Santos, Renato O; Maurer-Morelli, Claudia V; Cendes, Fernando; Lopes-Cendes, Iscia

    2017-01-01

    Mesial temporal lobe epilepsy is the most common form of adult epilepsy in surgical series. Currently, the only characteristic used to predict poor response to clinical treatment in this syndrome is the presence of hippocampal sclerosis. Single nucleotide polymorphisms (SNPs) located in genes encoding drug transporter and metabolism proteins could influence response to therapy. Therefore, we aimed to evaluate whether combining information from clinical variables as well as SNPs in candidate genes could improve the accuracy of predicting response to drug therapy in patients with mesial temporal lobe epilepsy. For this, we divided 237 patients into two groups: 75 responsive and 162 refractory to antiepileptic drug therapy. We genotyped 119 SNPs in ABCB1, ABCC2, CYP1A1, CYP1A2, CYP1B1, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4, and CYP3A5 genes. We used 98 additional SNPs to evaluate population stratification. We assessed a first scenario using only clinical variables and a second one including SNP information. The random forests algorithm combined with leave-one-out cross-validation was used to identify the best predictive model in each scenario and compared their accuracies using the area under the curve statistic. Additionally, we built a variable importance plot to present the set of most relevant predictors on the best model. The selected best model included the presence of hippocampal sclerosis and 56 SNPs. Furthermore, including SNPs in the model improved accuracy from 0.4568 to 0.8177. Our findings suggest that adding genetic information provided by SNPs, located on drug transport and metabolism genes, can improve the accuracy for predicting which patients with mesial temporal lobe epilepsy are likely to be refractory to drug treatment, making it possible to identify patients who may benefit from epilepsy surgery sooner.

  13. Atypical right hemisphere response to slow temporal modulations in children with developmental dyslexia.

    Science.gov (United States)

    Cutini, Simone; Szűcs, Dénes; Mead, Natasha; Huss, Martina; Goswami, Usha

    2016-12-01

    Phase entrainment of neuronal oscillations is thought to play a central role in encoding speech. Children with developmental dyslexia show impaired phonological processing of speech, proposed theoretically to be related to atypical phase entrainment to slower temporal modulations in speech (children with dyslexia have found atypical phase entrainment in the delta band (~2Hz), some studies of adults with developmental dyslexia have shown impaired entrainment in the low gamma band (~35-50Hz). Meanwhile, studies of neurotypical adults suggest asymmetric temporal sensitivity in auditory cortex, with preferential processing of slower modulations by right auditory cortex, and faster modulations processed bilaterally. Here we compared neural entrainment to slow (2Hz) versus faster (40Hz) amplitude-modulated noise using fNIRS to study possible hemispheric asymmetry effects in children with developmental dyslexia. We predicted atypical right hemisphere responding to 2Hz modulations for the children with dyslexia in comparison to control children, but equivalent responding to 40Hz modulations in both hemispheres. Analyses of HbO concentration revealed a right-lateralised region focused on the supra-marginal gyrus that was more active in children with dyslexia than in control children for 2Hz stimulation. We discuss possible links to linguistic prosodic processing, and interpret the data with respect to a neural 'temporal sampling' framework for conceptualizing the phonological deficits that characterise children with developmental dyslexia across languages. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  14. From indoor to outdoor: Behavioural response of fish to noise exposure of different temporal structures

    Directory of Open Access Journals (Sweden)

    Yik Yaw Neo

    2015-12-01

    Full Text Available Human activities, such as shipping and pile driving, produce substantial amounts of man-made noise underwater. The noise may negatively affect fish, causing physical injuries, hearing loss, physiological stress, acoustic masking and behavioural changes. Among these effects, behavioural changes are most problematic, but are understudied, especially under well-controlled field conditions. Moreover, man-made noise varies widely in terms of acoustic characteristics. The influence of temporal patterns of noise on the impacts is largely unknown. We exposed groups of European seabass to sound treatments of different temporal patterns, varying in intermittency, interval regularity and presence of amplitude 'ramp-up'. The study took place in a large octagonal floating pen (⌀ = ~12.5m in Oosterschelde, a marine inlet in the Netherlands. We tracked the fish swimming trajectories with an acoustic 3D telemetry system and looked into the behavioural changes and recovery. Upon noise exposure, the fish swam to greater depths in tighter shoals, similar to previous studies conducted in a basin. Moreover, the fish swam away from the noise source, suggesting avoidance behaviour. The different temporal patterns seemed to differ in their impact strengths although the results were not significant. These findings may carry important scientific and management implications.

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

    Science.gov (United States)

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

    2016-10-01

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

  16. Ocular-following responses to white noise stimuli in humans reveal a novel nonlinearity that results from temporal sampling.

    Science.gov (United States)

    Sheliga, Boris M; Quaia, Christian; FitzGibbon, Edmond J; Cumming, Bruce G

    2016-01-01

    White noise stimuli are frequently used to study the visual processing of broadband images in the laboratory. A common goal is to describe how responses are derived from Fourier components in the image. We investigated this issue by recording the ocular-following responses (OFRs) to white noise stimuli in human subjects. For a given speed we compared OFRs to unfiltered white noise with those to noise filtered with band-pass filters and notch filters. Removing components with low spatial frequency (SF) reduced OFR magnitudes, and the SF associated with the greatest reduction matched the SF that produced the maximal response when presented alone. This reduction declined rapidly with SF, compatible with a winner-take-all operation. Removing higher SF components increased OFR magnitudes. For higher speeds this effect became larger and propagated toward lower SFs. All of these effects were quantitatively well described by a model that combined two factors: (a) an excitatory drive that reflected the OFRs to individual Fourier components and (b) a suppression by higher SF channels where the temporal sampling of the display led to flicker. This nonlinear interaction has an important practical implication: Even with high refresh rates (150 Hz), the temporal sampling introduced by visual displays has a significant impact on visual processing. For instance, we show that this distorts speed tuning curves, shifting the peak to lower speeds. Careful attention to spectral content, in the light of this nonlinearity, is necessary to minimize the resulting artifact when using white noise patterns undergoing apparent motion.

  17. Quantifying the Temporal and Spatial Response of Channel Steepness to Changes in Rift Basin Architecture

    Science.gov (United States)

    Robinson, Scott M.

    Quantifying the temporal and spatial evolution of active continental rifts contributes to our understanding of fault system evolution and seismic hazards. Rift systems also preserve robust paleoenvironmental records and are often characterized by strong climatic gradients that can be used to examine feedbacks between climate and tectonics. In this thesis, I quantify the spatial and temporal history of rift flank uplift by analyzing bedrock river channel profiles along footwall escarpments in the Malawi segment of the East Africa Rift. This work addresses questions that are widely applicable to continental rift settings: (1) Is rift-flank uplift sufficiently described by theoretical elliptical along-fault displacement patterns? (2) Do orographic climate patterns induced by rift topography affect rift-flank uplift or morphology? (3) How do uplift patterns along rift flanks vary over geologic timescales? In Malawi, 100-km-long border faults of alternating polarity bound half-graben sedimentary basins containing up to 4km of basin fill and water depths up to 700m. Orographically driven precipitation produces climatic gradients along footwall escarpments resulting in mean annual rainfall that varies spatially from 800 to 2500 mm. Temporal oscillations in climate have also resulted in lake lowstands 500 m below the modern shoreline. I examine bedrock river profiles crossing the Livingstone and Usisya Border Faults in northern Malawi using the channel steepness index (Ksn) to assess importance of these conditions on rift flank evolution. River profiles reveal a consistent transient pattern that likely preserves a temporal record of slip and erosion along the entire border fault system. These profiles and other topographic observations, along with known modern and paleoenvironmental conditions, can be used to interpret a complete history of rift flank development from the onset of rifting to present. I interpret the morphology of the upland landscape to preserve the onset

  18. Leupeptin reduces impulse noise induced hearing loss

    Directory of Open Access Journals (Sweden)

    Gavriel Haim

    2011-12-01

    Full Text Available Abstract Background Exposure to continuous and impulse noise can induce a hearing loss. Leupeptin is an inhibitor of the calpains, a family of calcium-activated proteases which promote cell death. The objective of this study is to assess whether Leupeptin could reduce the hearing loss resulting from rifle impulse noise. Methods A polyethelene tube was implanted into middle ear cavities of eight fat sand rats (16 ears. Following determination of auditory nerve brainstem evoked response (ABR threshold in each ear, the animals were exposed to the noise of 10 M16 rifle shots. Immediately after the exposure, saline was then applied to one (control ear and non-toxic concentrations of leupeptin determined in the first phase of the study were applied to the other ear, for four consecutive days. Results Eight days after the exposure, the threshold shift (ABR in the control ears was significantly greater (44 dB than in the leupeptin ears (27 dB. Conclusion Leupeptin applied to the middle ear cavity can reduce the hearing loss resulting from exposure to impulse noise.

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

    Science.gov (United States)

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

    2015-10-01

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

  20. Force-Time Entropy of Isometric Impulse.

    Science.gov (United States)

    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.

  1. Cigarette cravings, impulsivity and the brain

    Directory of Open Access Journals (Sweden)

    Stéphane ePotvin

    2015-09-01

    Full Text Available 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 which impedes their self-control capacities and promotes 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, panning/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-cingular 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.

  2. Braking and propulsive impulses increase with speed during accelerated and decelerated walking.

    Science.gov (United States)

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

    2011-04-01

    The ability to accelerate and decelerate is important for daily activities and likely more demanding than maintaining a steady-state walking speed. Walking speed is modulated by anterior-posterior (AP) ground reaction force (GRF) impulses. The purpose of this study was to investigate AP impulses across a wide range of speeds during accelerated and decelerated walking. Kinematic and GRF data were collected from 10 healthy subjects walking on an instrumented treadmill. Subjects completed trials at steady-state speeds and at four rates of acceleration and deceleration across a speed range of 0-1.8 m/s. Mixed regression models were generated to predict AP impulses, step length and frequency from speed, and joint moment impulses from AP impulses during non-steady-state walking. Braking and propulsive impulses were positively related to speed. The braking impulse had a greater relationship with speed than the propulsive impulse, suggesting that subjects modulate the braking impulse more than the propulsive impulse to change speed. Hip and knee extensor, and ankle plantarflexor moment impulses were positively related to the braking impulse, and knee flexor and ankle plantarflexor moment impulses were positively related to the propulsive impulse. Step length and frequency increased with speed and were near the subjects' preferred combination at steady-state speeds, at which metabolic cost is minimized in nondisabled walking. Thus, these variables may be modulated to minimize metabolic cost while accelerating and decelerating. The outcomes of this work provide the foundation to investigate motor coordination in pathological subjects in response to the increased task demands of non-steady-state walking. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Echoic Memory: Investigation of Its Temporal Resolution by Auditory Offset Cortical Responses

    OpenAIRE

    Nishihara, Makoto; Inui, Koji; Morita, Tomoyo; Kodaira, Minori; Mochizuki, Hideki; Otsuru, Naofumi; Motomura, Eishi; Ushida, Takahiro; Kakigi, Ryusuke

    2014-01-01

    Previous studies showed that the amplitude and latency of the auditory offset cortical response depended on the history of the sound, which implicated the involvement of echoic memory in shaping a response. When a brief sound was repeated, the latency of the offset response depended precisely on the frequency of the repeat, indicating that the brain recognized the timing of the offset by using information on the repeat frequency stored in memory. In the present study, we investigated the temp...

  4. Determination of acoustical transfer functions using an impulse method

    Science.gov (United States)

    MacPherson, J.

    1985-02-01

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

  5. Brain Regions Related to Impulsivity Mediate the Effects of Early Adversity on Antisocial Behavior.

    Science.gov (United States)

    Mackey, Scott; Chaarani, Bader; Kan, Kees-Jan; Spechler, Philip A; Orr, Catherine; Banaschewski, Tobias; Barker, Gareth; Bokde, Arun L W; Bromberg, Uli; Büchel, Christian; Cattrell, Anna; Conrod, Patricia J; Desrivières, Sylvane; Flor, Herta; Frouin, Vincent; Gallinat, Jürgen; Gowland, Penny; Heinz, Andreas; Ittermann, Bernd; Paillère Martinot, Marie-Laure; Artiges, Eric; Nees, Frauke; Papadopoulos-Orfanos, Dimitri; Poustka, Luise; Smolka, Michael N; Jurk, Sarah; Walter, Henrik; Whelan, Robert; Schumann, Gunter; Althoff, Robert R; Garavan, Hugh

    2017-08-15

    Individual differences in impulsivity and early adversity are known to be strong predictors of adolescent antisocial behavior. However, the neurobiological bases of impulsivity and their relation to antisocial behavior and adversity are poorly understood. Impulsivity was estimated with a temporal discounting task. Voxel-based morphometry was used to determine the brain structural correlates of temporal discounting in a large cohort (n = 1830) of 14- to 15-year-old children. Mediation analysis was then used to determine whether the volumes of brain regions associated with temporal discounting mediate the relation between adverse life events (e.g., family conflict, serious accidents) and antisocial behaviors (e.g., precocious sexual activity, bullying, illicit substance use). Greater temporal discounting (more impulsivity) was associated with 1) lower volume in frontomedial cortex and bilateral insula and 2) greater volume in a subcortical region encompassing the ventral striatum, hypothalamus and anterior thalamus. The volume ratio between these cortical and subcortical regions was found to partially mediate the relation between adverse life events and antisocial behavior. Temporal discounting is related to regions of the brain involved in reward processing and interoception. The results support a developmental imbalance model of impulsivity and are consistent with the idea that negative environmental factors can alter the developing brain in ways that promote antisocial behavior. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  6. The Adolescent Coping Process Interview: measuring temporal and affective components of adolescent responses to peer stress.

    Science.gov (United States)

    Feagans Gould, Laura; Hussong, Andrea M; Keeley, Mary L

    2008-10-01

    The way in which adolescents cope with stressors in their lives has been established as an important correlate of adjustment. While most theoretical models of coping entail unfolding transactions between coping strategies and emotional arousal, the majority of coping measures tap only trait-level coping styles, ignoring both temporal and affective components of the coping process. The current study fills this gap by establishing the psychometric properties of a newly developed measure, the Adolescent Coping Process Interview (ACPI), that is more in line with transactional and developmental models of coping. Results indicate that the ACPI displays good psychometric properties, captures significant intra-individual variability in coping over the process, and points to emotional arousal as informing several coping-adjustment relationships. Moreover, the ACPI and similar approaches may help promote the development of more adaptive patterns of coping in adolescents by helping to identify specific points within the coping process at which to intervene.

  7. Bacterial metabolism in immediate response to nutritional perturbation with temporal and network view of metabolites.

    Science.gov (United States)

    Yukihira, Daichi; Fujimura, Yoshinori; Wariishi, Hiroyuki; Miura, Daisuke

    2015-09-01

    In this study, the initial propagation of metabolic perturbation in Escherichia coli was visualized to understand the dynamic characteristics of the metabolic pathways without the association of transcription alterations. E. coli cells were exposed to the sudden relief of glucose starvation, and time-dependent variances in metabolite balances were traced in the second scale. The acquired time-course data were represented by structural variations of the metabolite-metabolite correlation network. The initial correlation structure was altered immediately by the glucose pulse, followed by further structural variations within a few minutes. It was demonstrated that one metabolite temporally correlated with distinct metabolites with different timings, and such a behavior could imply a regulatory role for the metabolite in the metabolic network. Centrality analysis of the networks and partial correlation analysis indicated that preparation for growth and oxidative stress could be coupled as a structural property of the metabolic pathways.

  8. A collaborative large spatio-temporal data visual analytics architecture for emergence response

    International Nuclear Information System (INIS)

    Guo, D; Li, J; Zhou, Y; Cao, H

    2014-01-01

    The unconventional emergency, usually outbreaks more suddenly, and is diffused more quickly, but causes more secondary damage and derives more disaster than what it is usually expected. The data volume and urgency of emergency exceeds the capacity of current emergency management systems. In this paper, we propose a three-tier collaborative spatio-temporal visual analysis architecture to support emergency management. The prototype system, based on cloud computation environment, supports aggregation of massive unstructured and semi-structured data, integration of various computing model sand algorithms; collaborative visualization and visual analytics among users with a diversity of backgrounds. The distributed data in 100TB scale is integrated in a unified platform and shared with thousands of experts and government agencies by nearly 100 models. The users explore, visualize and analyse the big data and make a collaborative countermeasures to emergencies

  9. Impulsivity, Working Memory, and Impaired Control over Alcohol: A Latent Variable Analysis

    Science.gov (United States)

    Wardell, Jeffrey D.; Quilty, Lena C.; Hendershot, Christian S.

    2017-01-01

    Impaired control over alcohol is an important risk factor for heavy drinking among young adults and may mediate, in part, the association between personality risk and alcohol problems. Research suggests that trait impulsivity is associated with impaired control over alcohol; however, few studies of this association have included a range of impulsivity facets. The purpose of this study was to examine specific pathways from higher-order impulsivity factors to alcohol problems mediated via impaired control over alcohol. We also examined the moderating role of working memory in these associations. Young heavy drinkers (N=300) completed two multidimensional impulsivity measures (UPPS-P and BIS-11) along with self-report measures of impaired control over alcohol, alcohol use, and alcohol problems. Working memory was assessed using a computerized digit span task. Results showed that the impulsivity facets loaded onto two higher-order factors that were labeled response and reflection impulsivity. Response impulsivity predicted unique variance in self-reported impaired control and alcohol problems, whereas reflection impulsivity predicted unique variance in heavy drinking frequency only. Further, significant indirect associations were observed from response and reflection impulsivity to alcohol problems mediated via impaired control and heavy drinking frequency, respectively. Working memory and sensation seeking were not uniquely associated with the alcohol variables, and no support was found for the moderating role of working memory. The results help to clarify associations among impulsivity, impaired control, and alcohol problems, suggesting that impaired control may play a specific role in the pathway to alcohol problems from response impulsivity but not from reflection impulsivity. PMID:27269291

  10. Use of instant messaging predicts self-report but not performance measures of inattention, impulsiveness, and distractibility.

    Science.gov (United States)

    Levine, Laura E; Waite, Bradley M; Bowman, Laura L

    2013-12-01

    We examined how young adults' use of instant messaging, text messaging, and traditional reading related to their self-reported experience of distractibility and impulsiveness and to their performance on computerized tasks designed to assess inattention and impulsive responses to visual stimuli. Participants reported their media use and completed self-report measures of impulsiveness (i.e., the Barratt Impulsiveness Scale) and distractibility for academic reading. They also completed performance based measures of inattention and impulsiveness using the Tests of Variables of Attention (T.O.V.A.(®)). Results demonstrated that instant message use was significantly related to higher levels of attentional impulsiveness and distractibility on the self-report measures, while traditional reading consistently predicted lower levels of impulsiveness and distractibility. However, media use was not significantly related to the performance measures of inattention and behavioral impulsiveness.

  11. Temporal pattern and effect of sex on lipopolysaccharide-induced stress hormone and cytokine response in pigs.

    Science.gov (United States)

    Williams, P N; Collier, C T; Carroll, J A; Welsh, T H; Laurenz, J C

    2009-10-01

    The temporal pattern and sex effect of immune and stress hormone responses to a lipopolysaccharide (LPS) challenge were assessed using a pig model. Secretion of the pro-inflammatory cytokines tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6 increased in a time-dependent manner following LPS infusion. There was also a time-dependent increase in secretion of the stress-related hormones cortisol, epinephrine (E), and norepinephrine (NE) following LPS, with peak concentrations attained within 30 min. The magnitude of the TNF-alpha and IL-1beta responses were both positively associated (P immune cells in circulation was decreased (P immune cell counts increased (P gilts at 24h post-LPS (P immune- and stress-related hormones.

  12. Temporal change of photophobic step-up responses of Euglena gracilis investigated through motion analysis.

    Science.gov (United States)

    Ozasa, Kazunari; Won, June; Song, Simon; Tamaki, Shun; Ishikawa, Takahiro; Maeda, Mizuo

    2017-01-01

    The adaptation to a strong light is one of the essential characteristics of green algae, yet lacking relatively the information about the photophobic responses of Eukaryotic microalgae. We investigated the photophobic step-up responses of Euglena gracilis over a time course of several hours with alternated repetition of blue-light pulse illumination and spatially patterned blue-light illumination. Four distinctive photophobic motions in response to strong blue light were identified in a trace image analysis, namely on-site rotation, running and tumbling, continuous circular swimming, and unaffected straightforward swimming. The cells cultured in autotrophic conditions under weak light showed mainly the on-site rotation response at the beginning of blue-light illumination, but they acquired more blue-light tolerant responses of running and tumbling, circular swimming, or straightforward swimming. The efficiency of escaping from a blue-light illuminated area improved markedly with the development of these photophobic motions. Time constant of 3.0 h was deduced for the evolution of photophobic responses of E. gracilis. The nutrient-rich metabolic status of the cells resulting from photosynthesis during the experiments, i.e., the accumulation of photosynthesized nutrient products in balance between formation and consumption, was the main factor responsible for the development of photophobic responses. The reduction-oxidation status in and around E. gracilis cells did not affect their photophobic responses significantly, unlike the case of photophobic responses and phototaxis of Chlamydomonas reinhardtii cells. This study shows that the evolution of photophobic motion type of E. gracilis is dominated mainly by the nutrient metabolic status of the cells. The fact suggests that the nutrient-rich cells have a higher threshold for switching the flagellar motion from straightforward swimming to rotation under a strong light.

  13. Temporal change of photophobic step-up responses of Euglena gracilis investigated through motion analysis.

    Directory of Open Access Journals (Sweden)

    Kazunari Ozasa

    Full Text Available The adaptation to a strong light is one of the essential characteristics of green algae, yet lacking relatively the information about the photophobic responses of Eukaryotic microalgae. We investigated the photophobic step-up responses of Euglena gracilis over a time course of several hours with alternated repetition of blue-light pulse illumination and spatially patterned blue-light illumination. Four distinctive photophobic motions in response to strong blue light were identified in a trace image analysis, namely on-site rotation, running and tumbling, continuous circular swimming, and unaffected straightforward swimming. The cells cultured in autotrophic conditions under weak light showed mainly the on-site rotation response at the beginning of blue-light illumination, but they acquired more blue-light tolerant responses of running and tumbling, circular swimming, or straightforward swimming. The efficiency of escaping from a blue-light illuminated area improved markedly with the development of these photophobic motions. Time constant of 3.0 h was deduced for the evolution of photophobic responses of E. gracilis. The nutrient-rich metabolic status of the cells resulting from photosynthesis during the experiments, i.e., the accumulation of photosynthesized nutrient products in balance between formation and consumption, was the main factor responsible for the development of photophobic responses. The reduction-oxidation status in and around E. gracilis cells did not affect their photophobic responses significantly, unlike the case of photophobic responses and phototaxis of Chlamydomonas reinhardtii cells. This study shows that the evolution of photophobic motion type of E. gracilis is dominated mainly by the nutrient metabolic status of the cells. The fact suggests that the nutrient-rich cells have a higher threshold for switching the flagellar motion from straightforward swimming to rotation under a strong light.

  14. The ephemeral reward task: Pigeons and rats fail to learn unless discouraged from impulsive choice

    Directory of Open Access Journals (Sweden)

    Thomas R. Zentall

    2018-02-01

    Full Text Available The failure of certain species to learn a particular task while others learn it easily can help identify the learning mechanisms involved. In the ephemeral reward task, animals are given a choice between two distinctive stimuli, A and B, each containing an identical bit of food. If they choose A they get the food on A and the trial is over. If they choose B they get the food on B and they are allowed to get the food on A before the trial is over. Thus, it is optimal to choose B. Although cleaner fish (wrasse and parrots acquire the optimal response easily, several primate species do not. Furthermore, pigeons and rats also appear to be unable learn to choose optimally. The failure of primates, pigeons, and rats to learn this task and the ease with which cleaner fish and parrots learn it raises important questions about the learning mechanisms involved in those differences. To account for these paradoxical findings, we proposed that certain species may have difficulty with this task because they tend to respond impulsively to the initial choice which has similar immediate outcomes and they do not associate the choice and reinforcement with the second reinforcement. To test this hypothesis, we temporally separated the initial choice from the first reinforcement by imposing a 20-s delay between the choice and its outcome. Under these conditions both pigeons and rats gradually acquired the optimal choice response. We suggest that impulsive choice may make it difficult to acquire certain tasks and imposing a delay between choice and outcome may decrease impulsivity and allow for closer to optimal task performance.

  15. Impulse control disorders and depression.

    Science.gov (United States)

    Lejoyeux, Michel; Arbaretaz, Marie; McLoughlin, Mary; Adès, Jean

    2002-05-01

    This study assessed the frequency of impulse control disorders (ICDs) and their association with bulimia, compulsive buying, and suicide attempts in a population of depressed inpatients. We investigated ICDs using the Minnesota Impulsive Disorders Interview. Patients answered the Zuckerman Sensation-Seeking Scale and the Barratt Impulsivity Rating Scale. Among the 31 depressed patients who met criteria for ICD (ICD+ group), we found 18 cases of intermittent explosive disorder, three cases of pathological gambling, four cases of kleptomania, three cases of pyromania, and three cases of trichotillomania. Patients with co-occurring ICDs were significantly younger (mean age = 37.7 versus 42.8 years). Patients with kleptomania had a higher number of previous depressive episodes (5.7 versus 1.3), and patients with pyromania had a higher number of previous depressions (3.3 versus 1.3, p =.01). Bipolar disorders were more frequent in the ICD+ group than in the ICD- group (19% versus 1.3%, p =.002), whereas antisocial personality was not (3% versus 1%, p = ns). Bulimia (42% versus 10.5%, p =.005) and compulsive buying (51% versus 22%, p =.006) were significantly more frequent in the ICD+ group. Patients from the ICD+ group had higher scores of motor impulsivity assessed with the Barratt Impulsivity rating scale (p =.01).

  16. Olfaction in the Queensland fruit fly, Bactrocera tryoni. II: Response spectra and temporal encoding characteristics of the carbon dioxide receptors.

    Science.gov (United States)

    Hull, C D; Cribb, B W

    2001-05-01

    Single-unit electrophysiology was used to record the nerve impulses from the carbon dioxide receptors of female Queensland fruit flies, Bactroera tryoni. The receptors responded to stimulation in a phasic-tonic manner and also had a period of inhibition of the nerve impulses after the end of stimulation. at high stimulus intensities. The cell responding to carbon dioxide was presented with a range of environmental odorants and found to respond to methyl butyrate and 2-butanone. The coding characteristics of the carbon dioxide cell and the ability to detect other odorants are discussed, with particular reference to the known behavior of the fly.

  17. BOLD response to motion verbs in left posterior middle temporal gyrus during story comprehension.

    Science.gov (United States)

    Wallentin, Mikkel; Nielsen, Andreas Højlund; Vuust, Peter; Dohn, Anders; Roepstorff, Andreas; Lund, Torben Ellegaard

    2011-12-01

    A primary focus within neuroimaging research on language comprehension is on the distribution of semantic knowledge in the brain. Studies have shown that the left posterior middle temporal gyrus (LPMT), a region just anterior to area MT/V5, is important for the processing of complex action knowledge. It has also been found that motion verbs cause activation in LPMT. In this experiment we investigated whether this effect could be replicated in a setting resembling real life language comprehension, i.e. without any overt behavioral task during passive listening to a story. During fMRI participants listened to a recording of the story "The Ugly Duckling". We incorporated a nuisance elimination regression approach for factoring out known nuisance variables both in terms of physiological noise, sound intensity, linguistic variables and emotional content. Compared to the remaining text, clauses containing motion verbs were accompanied by a robust activation of LPMT with no other significant effects, consistent with the hypothesis that this brain region is important for processing motion knowledge, even during naturalistic language comprehension conditions. 2011 Elsevier Inc. All rights reserved.

  18. Temporal response of the tiger salamander (Ambystoma tigrinum to 3,000 years of climatic variation

    Directory of Open Access Journals (Sweden)

    Long Webb

    2005-09-01

    Full Text Available Abstract Background Amphibians are sensitive indicators of environmental conditions and show measurable responses, such as changes in phenology, abundance and range limits to local changes in precipitation and temperature regimes. Amphibians offer unique opportunities to study the important ecological and evolutionary implications of responses in life history characteristics to climatic change. We analyzed a late-Holocene fossil record of the Tiger Salamander (Ambystoma tigrinum for evidence of population-level changes in body size and paedomorphosis to climatic change over the last 3000 years. Results We found a significant difference in body size index between paedomorphic and metamorphic individuals during the time interval dominated by the Medieval Warm Period. There is a consistent ratio of paedomorphic to metamorphic specimens through the entire 3000 years, demonstrating that not all life history characteristics of the population were significantly altered by changes in climate on this timescale. Conclusion The fossil record of Ambystoma tigrinum we used spans an ecologically relevant timescale appropriate for understanding population and community response to projected climatic change. The population-level responses we documented are concordant with expectations based on modern environmental studies, and yield insight into population-level patterns across hundreds of generations, especially the independence of different life history characteristics. These conclusions lead us to offer general predictions about the future response of this species based on likely scenarios of climatic warming in the Rocky Mountain region.

  19. Temporal response of the tiger salamander (Ambystoma tigrinum) to 3,000 years of climatic variation.

    Science.gov (United States)

    Bruzgul, Judsen E; Long, Webb; Hadly, Elizabeth A

    2005-09-13

    Amphibians are sensitive indicators of environmental conditions and show measurable responses, such as changes in phenology, abundance and range limits to local changes in precipitation and temperature regimes. Amphibians offer unique opportunities to study the important ecological and evolutionary implications of responses in life history characteristics to climatic change. We analyzed a late-Holocene fossil record of the Tiger Salamander (Ambystoma tigrinum) for evidence of population-level changes in body size and paedomorphosis to climatic change over the last 3000 years. We found a significant difference in body size index between paedomorphic and metamorphic individuals during the time interval dominated by the Medieval Warm Period. There is a consistent ratio of paedomorphic to metamorphic specimens through the entire 3000 years, demonstrating that not all life history characteristics of the population were significantly altered by changes in climate on this timescale. The fossil record of Ambystoma tigrinum we used spans an ecologically relevant timescale appropriate for understanding population and community response to projected climatic change. The population-level responses we documented are concordant with expectations based on modern environmental studies, and yield insight into population-level patterns across hundreds of generations, especially the independence of different life history characteristics. These conclusions lead us to offer general predictions about the future response of this species based on likely scenarios of climatic warming in the Rocky Mountain region.

  20. Impulsivity, "advergames," and food intake.

    Science.gov (United States)

    Folkvord, Frans; Anschütz, Doeschka J; Nederkoorn, Chantal; Westerik, Henk; Buijzen, Moniek

    2014-06-01

    Previous studies have focused on the effect of food advertisements on the caloric intake of children. However, the role of individual susceptibility in this effect is unclear. The aim of this study was to examine the role of impulsivity in the effect of advergames that promote energy-dense snacks on children's snack intake. First, impulsivity scores were assessed with a computer task. Then a randomized between-subject design was conducted with 261 children aged 7 to 10 years who played an advergame promoting either energy-dense snacks or nonfood products. As an extra manipulation, half of the children in each condition were rewarded for refraining from eating, the other half were not. Children could eat freely while playing the game. Food intake was measured. The children then completed questionnaire measures, and were weighed and measured. Overall, playing an advergame containing food cues increased general caloric intake. Furthermore, rewarding children to refrain from eating decreased their caloric intake. Finally, rewarding impulsive children to refrain from eating had no influence when they were playing an advergame promoting energy-dense snacks, whereas it did lead to reduced intake among low impulsive children and children who played nonfood advergames. Playing an advergame promoting energy-dense snacks contributes to increased caloric intake in children. The advergame promoting energy-dense snacks overruled the inhibition task to refrain from eating among impulsive children, making it more difficult for them to refrain from eating. The findings suggest that impulsivity plays an important role in susceptibility to food advertisements. Copyright © 2014 by the American Academy of Pediatrics.

  1. NORMATIVE MODERATORS OF IMPULSE BUYING BEHAVIOR

    Directory of Open Access Journals (Sweden)

    Danes Jaya Negara

    2003-01-01

    Full Text Available Prior research has presented the moderating role of normative evaluations in the relationship between the impulsive buying trait and consumers’ buying behaviors. In this article the authors show that consumer tendency to buy something spontaneous, unreflectively and immediately can be perceived as a factor which describes buying impulsiveness. This article also shows conceptual and empirical evidence that there is some support for the moderating role of normative evaluations in the relationship between buying impulsiveness and impulse buying behaviors. Significance occurs when consumers believe that act on impulse is suitable. The result suggests that consumers’ normative evaluation can moderate the link between the trait and behavioral aspects of impulse buying.

  2. Large sensitivity in land carbon storage due to geographical and temporal variation in the thermal response of photosynthetic capacity.

    Science.gov (United States)

    Mercado, Lina M; Medlyn, Belinda E; Huntingford, Chris; Oliver, Rebecca J; Clark, Douglas B; Sitch, Stephen; Zelazowski, Przemyslaw; Kattge, Jens; Harper, Anna B; Cox, Peter M

    2018-04-10

    Plant temperature responses vary geographically, reflecting thermally contrasting habitats and long-term species adaptations to their climate of origin. Plants also can acclimate to fast temporal changes in temperature regime to mitigate stress. Although plant photosynthetic responses are known to acclimate to temperature, many global models used to predict future vegetation and climate-carbon interactions do not include this process. We quantify the global and regional impacts of biogeographical variability and thermal acclimation of temperature response of photosynthetic capacity on the terrestrial carbon (C) cycle between 1860 and 2100 within a coupled climate-carbon cycle model, that emulates 22 global climate models. Results indicate that inclusion of biogeographical variation in photosynthetic temperature response is most important for present-day and future C uptake, with increasing importance of thermal acclimation under future warming. Accounting for both effects narrows the range of predictions of the simulated global land C storage in 2100 across climate projections (29% and 43% globally and in the tropics, respectively). Contrary to earlier studies, our results suggest that thermal acclimation of photosynthetic capacity makes tropical and temperate C less vulnerable to warming, but reduces the warming-induced C uptake in the boreal region under elevated CO 2 . © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

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

    Science.gov (United States)

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

    2017-09-27

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

  4. Measuring and modeling spatio-temporal patterns of groundwater storage dynamics to better understand nonlinear streamflow response

    Science.gov (United States)

    Rinderer, Michael; van Meerveld, Ilja; McGlynn, Brian

    2017-04-01

    Information about the spatial and temporal variability in catchment scale groundwater storage is needed to identify runoff source area dynamics and better understand variability in streamflow. However, information on groundwater levels is typically only available at a limited number of monitoring sites and interpolation or upscaling is necessary to obtain information on catchment scale groundwater dynamics. Here we used data from 51 spatially distributed groundwater monitoring sites in a Swiss pre-alpine catchment and time series clustering to define six groundwater response clusters. Each of the clusters was distinct in terms of the groundwater rise and recession but also had distinctly different topographic site characteristics, which allowed us to assign a groundwater response cluster to all non-monitored locations. Each of them was then assigned the mean groundwater response of the monitored cluster members. A site was considered active (i.e., enabling lateral subsurface flow) when the groundwater levels rose above the groundwater response threshold which was defined based on the depth of the more transmissive soil layers (typically between 10 cm and 30 cm below the soil surface). This allowed us to create maps of the active areas across the catchment at 15 min time intervals. The mean fraction of agreement between modeled groundwater activation (based on the mean cluster member time series) and measured groundwater activation (based on the measured groundwater level time series at a monitoring site) was 0.91 (25th percentile: 0.88, median: 0.92, 75th percentile: 0.95). The fraction of agreement dropped by 10 to 15 % at the beginning of events but was never lower than 0.4. Connectivity between all active areas and the stream network was determined using a graph theory approach. During rainfall events, the simulated active and connected area extended mainly laterally and longitudinally along the channel network, which is in agreement with the variable source

  5. Chaos in periodically forced Holling type IV predator-prey system with impulsive perturbations

    International Nuclear Information System (INIS)

    Zhang Shuwen; Tan Dejun; Chen Lansun

    2006-01-01

    The effect of periodic forcing and impulsive perturbations on predator-prey model with Holling type IV functional response is investigated. The periodic forcing is affected by assuming a periodic variation in the intrinsic growth rate of the prey. The impulsive perturbations are affected by introducing periodic constant impulsive immigration of predator. The dynamical behavior of the system is simulated and bifurcation diagrams are obtained for different parameters. The results show that periodic forcing and impulsive perturbation can easily give rise to complex dynamics, including (1) quasi-periodic oscillating, (2) period doubling cascade, (3) chaos, (4) period halfing cascade

  6. Chaos in periodically forced Holling type II predator-prey system with impulsive perturbations

    International Nuclear Information System (INIS)

    Zhang Shuwen; Tan Dejun; Chen Lansun

    2006-01-01

    The effect of periodic forcing and impulsive perturbations on predator-prey model with Holling type II functional response is investigated. The periodic forcing is affected by assuming a periodic variation in the intrinsic growth rate of prey. The impulsive perturbation is affected by introducing periodic constant impulsive immigration of predator. The dynamical behavior of the system is simulated and bifurcation diagrams are obtained for different parameters. The results show that periodic forcing and impulsive perturbation can very easily give rise to complex dynamics, including (1) quasi-periodic oscillating, (2) period doubling cascade, (3) chaos, (4) period halfing cascade, (5) non-unique dynamics

  7. Exploiting temporal variability to understand tree recruitment response to climate change

    Science.gov (United States)

    Ines Ibanez; James S. Clark; Shannon LaDeau; Janneke Hill Ris Lambers

    2007-01-01

    Predicting vegetation shifts under climate change is a challenging endeavor, given the complex interactions between biotic and abiotic variables that influence demographic rates. To determine how current trends and variation in climate change affect seedling establishment, we analyzed demographic responses to spatiotemporal variation to temperature and soil moisture in...

  8. The use of antioxidant enzymes in freshwater biofilms: temporal variability vs. toxicological responses.

    Science.gov (United States)

    Bonnineau, Chloé; Tlili, Ahmed; Faggiano, Leslie; Montuelle, Bernard; Guasch, Helena

    2013-07-15

    This study aims to investigate the potential of antioxidant enzyme activities (AEA) as biomarkers of oxidative stress in freshwater biofilms. Therefore, biofilms were grown in channels for 38 days and then exposed to different concentrations (0-150 μg L(-1)) of the herbicide oxyfluorfen for 5 more weeks. Under control conditions, the AEA of biofilms were found to change throughout time with a significant increase in ascorbate peroxidase (APX) activity during the exponential growth and a more important role of catalase (CAT) and glutathione reductase (GR) activities during the slow growth phase. Chronic exposure to oxyfluorfen led to slight variations in AEA, however, the ranges of variability of AEA in controls and exposed communities were similar, highlighting the difficulty of a direct interpretation of AEA values. After 5 weeks of exposure to oxyfluorfen, no clear effects were observed on chl-a concentration or on the composition of other pigments suggesting that algal group composition was not affected. Eukaryotic communities were structured clearly by toxicant concentration and both eukaryotic and bacterial richness were reduced in communities exposed to the highest concentration. In addition, during acute exposure tests performed at the end of the chronic exposure, biofilms chronically exposed to 75 and 150 μg L(-1) oxyfluorfen showed a higher CAT activity than controls. Chronic exposure to oxyfluorfen provoked then structural changes but also functional changes in the capacity of biofilm CAT activity to respond to a sudden increase in concentration, suggesting a selection of species with higher antioxidant capacity. This study highlighted the difficulty of interpretation of AEA values due to their temporal variation and to the absence of absolute threshold value indicative of oxidative stress induced by contaminants. Nevertheless, the determination of AEA pattern throughout acute exposure test is of high interest to compare oxidative stress levels

  9. Temporal genetic stability in natural populations of the waterflea Daphnia magna in response to strong selection pressure.

    Science.gov (United States)

    Orsini, Luisa; Marshall, Hollie; Cuenca Cambronero, Maria; Chaturvedi, Anurag; Thomas, Kelley W; Pfrender, Michael E; Spanier, Katina I; De Meester, Luc

    2016-12-01

    Studies monitoring changes in genetic diversity and composition through time allow a unique understanding of evolutionary dynamics and persistence of natural populations. However, such studies are often limited to species with short generation times that can be propagated in the laboratory or few exceptional cases in the wild. Species that produce dormant stages provide powerful models for the reconstruction of evolutionary dynamics in the natural environment. A remaining open question is to what extent dormant egg banks are an unbiased representation of populations and hence of the species' evolutionary potential, especially in the presence of strong environmental selection. We address this key question using the water flea Daphnia magna, which produces dormant stages that accumulate in biological archives over time. We assess temporal genetic stability in three biological archives, previously used in resurrection ecology studies showing adaptive evolutionary responses to rapid environmental change. We show that neutral genetic diversity does not decline with the age of the population and it is maintained in the presence of strong selection. In addition, by comparing temporal genetic stability in hatched and unhatched populations from the same biological archive, we show that dormant egg banks can be consulted to obtain a reliable measure of genetic diversity over time, at least in the multidecadal time frame studied here. The stability of neutral genetic diversity through time is likely mediated by the buffering effect of the resting egg bank. © 2016 John Wiley & Sons Ltd.

  10. Modulating presence and impulsiveness by external stimulation of the brain

    Directory of Open Access Journals (Sweden)

    Baumgartner Thomas

    2008-08-01

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

  11. Antisaccadic training to improve impulsivity in binge eating disorder.

    Science.gov (United States)

    Giel, Katrin Elisabeth; Schag, Kathrin; Plewnia, Christian; Zipfel, Stephan

    2013-11-01

    Patients with binge eating disorder (BED) show generally increased impulsivity and especially increased food-related impulsivity. Both are closely linked to the core pathology of BED, which relates to regular binge eating episodes with experienced loss of control. The antisaccade task is an established paradigm assessing response inhibition as a pivotal component of impulsivity. It requires participants to execute antisaccades; that is, they are supposed to look in the opposite direction of a stimulus that automatically catches attention by appearing in the peripheral visual field. High rates of prosaccades to the peripheral stimuli are considered indicators of increased impulsivity. Presenting food pictures as peripheral stimuli, this task can be used to investigate food-related impulsivity. We propose modifications of this task in order to design it as an antisaccadic training in which BED patients practise the suppression of food-related responses, which should result in enhanced control over their eating behaviour. Copyright © 2013 John Wiley & Sons, Ltd and Eating Disorders Association.

  12. Depression and Impulsivity as Pathways to Violence: Implications for Antiaggressive Treatment

    Science.gov (United States)

    Krakowski, Menahem I.; Czobor, Pal

    2014-01-01

    Background: Difficulties with affect regulation and impulse control have a strong influence on violence. The objective of this study was to determine whether baseline depression and impulsivity predict aggression and whether they predict differential response to antiaggressive treatment. This is important, as we lack knowledge as to the selection of antipsychotics for the treatment of aggression. Methods: Physically aggressive inpatients with schizophrenia who received an evaluation of depression and impulsivity at baseline were randomly assigned in a double-blind, parallel group, 12-week trial to clozapine, olanzapine, or haloperidol. Trait impulsivity was measured by the Barratt Impulsiveness Scale; depression by the Positive and Negative Syndrome Scale Depression factor. The number and severity of aggressive events, as measured by the Modified Overt Aggression Scale (MOAS), were the outcome measures. Results: Baseline depression and impulsivity predicted higher levels of aggression, as measured by the MOAS total score, over the 12-week treatment period across all 3 medication groups. In addition, there was a strong interaction effect between baseline depression/impulsivity and medication grouping in predicting MOAS score. In particular, when higher depression and impulsivity were present at baseline, patients on haloperidol presented with more aggression than patients on the other 3 medications. Conclusions: Depression and impulsivity are important predictors of aggression and of differential response to antiaggressive treatment. This is most likely due to the medications’ dissimilar neurotransmitter profiles. By identifying patients who will respond better to a given medication, we will be able to develop individualized strategies for the treatment of violent behavior. PMID:23943412

  13. Subthalamic nucleus stimulation, dopaminergic treatment and impulsivity in Parkinson's disease.

    Science.gov (United States)

    Fluchère, Frédérique; Burle, Borís; Vidal, Franck; van den Wildenberg, Wery; Witjas, Tatiana; Eusebio, Alexandre; Azulay, Jean-Philippe; Hasbroucq, Thierry

    2018-02-16

    Deep brain stimulation of the subthalamic nucleus (STN DBS) is known to increase response speed and lower response accuracy in Parkinson's disease (PD) patients. It has been proposed that this speed-accuracy tradeoff is due to enhanced sensitivity of the motor system to sensory information. An alternative possibility is that this effect is due to weakened suppressive processes. The two alternative interpretations can be tested by analyzing the electromyographic activity (EMG) of the response agonists when the patients perform conflict reaction time tasks. In those tasks, fast subthreshold muscle impulses often occur in the agonist of the incorrect response. These impulses are partial errors that are suppressed before being behaviourally committed. Here we analyzed the EMG of the response agonists recorded while sixteen PD patients performed a Simon task that elicits prepotent response tendencies so as to decipher (i) whether STN DBS affects the expression and/or suppression of subthreshold muscle impulses that are critical for action control and (ii) the interaction between dopaminergic treatment and STN DBS. The patients were tested On and Off STN DBS and On and Off dopaminergic medication in a full factorial design. STN DBS not only impaired the proficiency to suppress subliminal action impulses (p = 0.01) but also favoured the muscular expression of fast incorrect impulses (p<0.001). Dopaminergic treatment only affected the action impulses suppression (p = 0.02) and did not change the effect of STN DBS on impulsive action control. Contrary to a recent proposal, STN DBS impaired rather than improved action control by weakening erroneous impulse suppression, whether the patients were On or Off their usual medication. These findings are discussed in light of a recent proposal (Servant M, White C, Montagnini A, Burle B, 2015) that reconciles partial errors with accumulation-to-bound models of decision making. Our results suggest that medication specifically lowers

  14. Temporally Diverse Excitation Generates Direction-Selective Responses in ON- and OFF-Type Retinal Starburst Amacrine Cells

    Directory of Open Access Journals (Sweden)

    James W. Fransen

    2017-02-01

    Full Text Available The complexity of sensory receptive fields increases from one synaptic stage to the next. In many cases, increased complexity is achieved through spatiotemporal interactions between convergent excitatory and inhibitory inputs. Here, we present evidence that direction selectivity (DS, a complex emergent receptive field property of retinal starburst amacrine cells (SACs, is generated by spatiotemporal interactions between functionally diverse excitatory inputs. Electrophysiological whole-cell recordings from ON and OFF SACs show distinct temporal differences in excitation following proximal compared with distal stimulation of their receptive fields. Distal excitation is both faster and more transient, ruling out passive filtering by the dendrites and indicating a task-specific specialization. Model simulations demonstrate that this specific organization of excitation generates robust DS responses in SACs, consistent with elementary motion detector models. These results indicate that selective integration of spatiotemporally patterned excitation is a computational mechanism for motion detection in the mammalian retina.

  15. Involuntary and voluntary recall of musical memories: A comparison of temporal accuracy and emotional responses.

    Science.gov (United States)

    Jakubowski, Kelly; Bashir, Zaariyah; Farrugia, Nicolas; Stewart, Lauren

    2018-01-29

    Comparisons between involuntarily and voluntarily retrieved autobiographical memories have revealed similarities in encoding and maintenance, with differences in terms of specificity and emotional responses. Our study extended this research area into the domain of musical memory, which afforded a unique opportunity to compare the same memory as accessed both involuntarily and voluntarily. Specifically, we compared instances of involuntary musical imagery (INMI, or "earworms")-the spontaneous mental recall and repetition of a tune-to deliberate recall of the same tune as voluntary musical imagery (VMI) in terms of recall accuracy and emotional responses. Twenty participants completed two 3-day tasks. In an INMI task, participants recorded information about INMI episodes as they occurred; in a VMI task, participants were prompted via text message to deliberately imagine each tune they had previously experienced as INMI. In both tasks, tempi of the imagined tunes were recorded by tapping to the musical beat while wearing an accelerometer and additional information (e.g., tune name, emotion ratings) was logged in a diary. Overall, INMI and VMI tempo measurements for the same tune were strongly correlated. Tempo recall for tunes that have definitive, recorded versions was relatively accurate, and tunes that were retrieved deliberately (VMI) were not recalled more accurately in terms of tempo than spontaneous and involuntary instances of imagined music (INMI). Some evidence that INMI elicited stronger emotional responses than VMI was also revealed. These results demonstrate several parallels to previous literature on involuntary memories and add new insights on the phenomenology of INMI.

  16. Temporal dissociation of salience and prediction error responses to appetitive and aversive taste.

    Science.gov (United States)

    Hird, E J; El-Deredy, W; Jones, A; Talmi, D

    2018-02-01

    The feedback-related negativity (FRN), a frontocentral ERP occurring 200-350 ms after emotionally valued outcomes, has been posited as the neural correlate of reward prediction error, a key component of associative learning. Recent evidence challenged this interpretation and has led to the suggestion that this ERP expresses salience instead. Here, we distinguish between utility prediction error and salience by delivering or withholding hedonistically matched appetitive and aversive tastes, and measure ERPs to cues signaling each taste. We observed a typical FRN (computed as the loss-minus-gain difference wave) to appetitive taste, but a reverse FRN to aversive taste. When tested axiomatically, frontocentral ERPs showed a salience response across tastes, with a particularly early response to outcome delivery, supporting recent propositions of a fast, unsigned, and unspecific response to salient stimuli. ERPs also expressed aversive prediction error peaking at 285 ms, which conformed to the logic of an axiomatic model of prediction error. With stimuli that most resemble those used in animal models, we did not detect any frontocentral ERP signal for utility prediction error, in contrast with dominant views of the functional role of the FRN ERP. We link the animal and human literature and present a challenge for current perspectives on associative learning research using ERPs. © 2017 Society for Psychophysiological Research.

  17. Temporal analysis of a dose-response relationship: leukemia mortality in atomic bomb survivors.

    Science.gov (United States)

    Brodsky, J B; Groer, P G; Liddell, R; Ishimaru, T; Ichimaru, M

    1984-09-01

    A data analysis that incorporates time dependencies is demonstrated for the dose response of leukemia mortality in the atomic bomb survivors. The time dependencies are initially left unspecified and the data on leukemia mortality--up to the end of 1978--are used to infer them. Several findings based on T65 revised doses (T65DR) are obtained. First, it is shown that the fits to the data of time-dependent L (linear in gamma dose)-Q (quadratic in gamma dose)-L (linear in neutron dose), L-L, and Q-L dose-response models are significantly improved (P less than 0.001) by using the corresponding time-dependent dose-response models. Second, it is shown that the increased risk of leukemia mortality due to gamma irradiation decreases in time while the increased risk due to neutron exposure decreases more slowly, if at all, in time. Consequently, relative biological effectiveness (RBE) of neutrons is shown to increase in time (P = 0.002) and the current definition of RBE as a time-independent quantity is therefore challenged. It is demonstrated with time-dependent models that the L-L model has a poor fit (P = 0.01) to the data for the first 7 years of study, but has an adequate fit for the remaining 21 years. In contrast the Q-L model has an adequate fit for the entire follow-up period (P greater than 0.30).

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

    Science.gov (United States)

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

    2015-01-01

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

  19. Dopaminergic influences on executive function and impulsive behaviour in impulse control disorders in Parkinson's disease.

    Science.gov (United States)

    Leroi, Iracema; Barraclough, Michelle; McKie, Shane; Hinvest, Neal; Evans, Jonathan; Elliott, Rebecca; McDonald, Kathryn

    2013-09-01

    The development of impulse control disorders (ICDs) in Parkinson's disease (PD) may arise from an interaction among cognitive impairment, impulsive responding and dopaminergic state. Dopaminergic state may be influenced by pharmacologic or genotypic (catechol-O-methyltransferase; COMT) factors. We sought to investigate this interaction further by comparing those with (n = 35) and without (n = 55) ICDs on delay-discounting in different pharmacologic conditions (ON or OFF dopaminergic medication) and on response inhibition as well as aspects of executive functioning in the ON state. We then undertook an exploratory sub-group analysis of these same tasks when the overall PD group was divided into different allelic variants of COMT (val/val vs. met/met). A healthy control group (HC; n = 20) was also included. We found that in those with PD and ICDs, 'cognitive flexibility' (set shifting, verbal fluency, and attention) in the ON medication state was not impaired compared with those without ICDs. In contrast, our working memory, or 'cognitive focus', task was impaired in both PD groups compared with the HC group when ON. During the delay-discounting task, the PD with ICDs group expressed greater impulsive choice compared with the PD group without ICDs, when in the ON, but not the OFF, medication state. However, no group difference on the response inhibition task was seen when ON. Finally, the met homozygous group performed differently on tests of executive function compared with the val homozygous group. We concluded that the disparity in levels of impairment among different domains of executive function and impulsive decision-making distinguishes those with ICD in PD from those without ICD, and may in part be affected by dopaminergic status. Both pharmacologic and genotypic influences on dopaminergic state may be important in ICD. © 2013 The British Psychological Society.

  20. Experiment on Impulsive Excitation, Resonance, and Fourier Analysis of a Harmonic Oscillator.

    Science.gov (United States)

    Macomber, Hilliard K.

    1981-01-01

    Describes an electric circuit permitting easy observation and measurement of the response of a damped harmonic oscillator to impulsive excitation. The impulse analysis is carried out and related to experimental observations. The phenomenon of resonance is then interpreted and demonstrated, and through it, contact is made with Fourier analysis.…

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

    NARCIS (Netherlands)

    Wel, J. van; Spronk, D.B.; Kuypers, K.; Theunissen, E.; Toennes, S.; Verkes, R.J.; Ramaekers, J.

    2015-01-01

    Trait impulsivity has been linked to addiction in humans. It has been suggested that drug users with high trait impulsivity levels are more sensitive to subjective drug intoxication. This study assessed whether subjective response to drugs differs between drug users with normal or high levels of

  2. The role of impulsivity in relapse vulnerability

    NARCIS (Netherlands)

    Pattij, T.; de Vries, T.J.

    2013-01-01

    Drug dependence in humans is often accompanied by behavioral disturbances such as maladaptive levels of impulsivity. In turn, there is accumulating evidence from preclinical laboratory animal and clinical studies indicating that impulsive behavior might be causally linked to several distinct

  3. Impulse: Memory System Support for Scientific Applications

    Directory of Open Access Journals (Sweden)

    John B. Carter

    1999-01-01

    Full Text Available Impulse is a new memory system architecture that adds two important features to a traditional memory controller. First, Impulse supports application‐specific optimizations through configurable physical address remapping. By remapping physical addresses, applications control how their data is accessed and cached, improving their cache and bus utilization. Second, Impulse supports prefetching at the memory controller, which can hide much of the latency of DRAM accesses. Because it requires no modification to processor, cache, or bus designs, Impulse can be adopted in conventional systems. In this paper we describe the design of the Impulse architecture, and show how an Impulse memory system can improve the performance of memory‐bound scientific applications. For instance, Impulse decreases the running time of the NAS conjugate gradient benchmark by 67%. We expect that Impulse will also benefit regularly strided, memory‐bound applications of commercial importance, such as database and multimedia programs.

  4. Seed dormancy responses to temperature relate to Nothofagus species distribution and determine temporal patterns of germination across altitudes in Patagonia.

    Science.gov (United States)

    Arana, María V; Gonzalez-Polo, Marina; Martinez-Meier, Alejandro; Gallo, Leonardo A; Benech-Arnold, Roberto L; Sánchez, Rodolfo A; Batlla, Diego

    2016-01-01

    Seeds integrate environmental cues that modulate their dormancy and germination. Although many mechanisms have been identified in laboratory experiments, their contribution to germination dynamics in existing communities and their involvement in defining species habitats remain elusive. By coupling mathematical models with ecological data we investigated the contribution of seed temperature responses to the dynamics of germination of three Nothofagus species that are sharply distributed across different altitudes in the Patagonian Andes. Seed responsiveness to temperature of the three Nothofagus species was linked to the thermal characteristics of their preferred ecological niche. In their natural distribution range, there was overlap in the timing of germination of the species, which was restricted to mid-spring. By contrast, outside their species distribution range, germination was temporally uncoupled with altitude. This phenomenon was described mathematically by the interplay between interspecific differences in seed population thermal parameters and the range in soil thermic environments across different altitudes. The observed interspecific variations in seed responsiveness to temperature and its environmental regulation, constitute a major determinant of the dynamics of Nothofagus germination across elevations. This phenomenon likely contributes to the maintenance of patterns of species abundance across altitude by placing germinated seeds in a favorable environment for plant growth. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  5. Impulse sales cooler. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, Per Henrik (DTI, Taastrup (Denmark))

    2010-11-15

    In the past years, the use of impulse coolers has increased considerably and it is estimated that at least 30.000 are installed in shops in Denmark. In addition, there are many small barrel-shaped can coolers. Most impulse coolers are open, which results in a large consumption of energy, and the refrigeration systems are often quite inefficient. A typical impulse cooler uses app. 5 - 8 kWh/day corresponding to a consumption of energy in the magnitude of 60 GWh/year. For several years, the Danish company Vestfrost A/S has produced an impulse sales cooler in the high-efficiency end and the energy consumption of the cooler is measured to be 4.15 kWh/day. The POS72 cooler formed the baseline of this project. At the start-up meeting in 2008, several ideas were discussed with the objective to reduce energy consumption and to use natural refrigerants. Among the ideas were better air curtains, removable lids, better condensers, use of R600a refrigeration system and better insulation. Three generations of prototypes were built and tested in a climate chamber at Danish Technological Institute and the third generation showed very good performance: the energy consumption was measured to 2.215 kWh/day, which is a 47% reduction compared to the baseline. That was achieved by: 1) Improving the cold air cycling system including the air curtain. 2) Using the natural refrigerant R600a (isobutane) and the Danfoss NLE9KTK compressor, which has better efficiency compared to the compressor in the baseline product. 3) Using a box type condenser without fins (preventing dust build-up) and with a relatively high surface area. 4) Improving the insulation value of the plastic cabinet by reducing turbulence in the air gap between the plastic walls and improving the insulation value of the EPS moulded insulation surrounding the refrigeration system at the bottom of the cooler. 5) Preventing short-circuit of warm air around the condenser. 6) The improvements are cost efficient and will not add

  6. Temporal response of protein-based artificial ganglion cell receptive field (Conference Presentation)

    Science.gov (United States)

    Okada-Shudo, Yoshiko

    2016-10-01

    We propose ganglion cell receptive-field-type filters with the use of the photoreceptor protein bacteriorhodopsin. Visual image processing is possible with the use of only one sensing element. We also demonstrate that our difference of Gaussians (DOG) filter, which mimics on-center off-suround ganglion cell receptive fields, has the function of a Laplacian filter and can act as an edge detecor. The X-type receptive field responses obtained by the filter, for a variety of stimuli, are compared with available electrophysiological recodings.

  7. Responses of woody species to spatial and temporal ground water changes in coastal sand dune systems

    Directory of Open Access Journals (Sweden)

    C. Máguas

    2011-12-01

    Full Text Available In spite of the relative importance of groundwater in costal dune systems, studies concerning the responses of vegetation to ground water (GW availability variations, particularly in Mediterranean regions, are scarce. Thus, the main purpose of this study is to compare the responses of co-occurring species possessing different functional traits, to changes in GW levels (i.e. the lowering of GW levels in a sand dune ecosystem. For that, five sites were established within a 1 km2 area in a meso-mediterranean sand dune ecosystem dominated by a Pinus pinaster forest. Due to natural topographic variability and anthropogenic GW exploitation, substantial variability in depth to GW between sites was found. Under these conditions it was possible to identify the degree of usage and dependence on GW of different plant species (two deep-rooted trees, a drought adapted shrub, a phreatophyte and a non-native woody invader and how GW dependence varied seasonally and between the heterogeneous sites. Results indicated that the plant species had differential responses to changes in GW depth according to specific functional traits (i.e. rooting depth, leaf morphology, and water use strategy. Species comparison revealed that variability in pre-dawn water potential (Ψpre and bulk leaf δ13C was related to site differences in GW use in the deep-rooted (Pinus pinaster, Myrica faya and phreatophyte (Salix repens species. However, such variation was more evident during spring than during summer drought. The exotic invader, Acacia longifolia, which does not possess a very deep root system, presented the largest seasonal variability in Ψpre and bulk leaf δ13C. In contrast, the response of Corema album, an endemic understory drought-adapted shrub, seemed to be independent of water availability across seasons and sites. Thus, the susceptibility to lowering of GW due to anthropogenic

  8. Temporal Regulation of Natural Killer T Cell Interferon Gamma Responses by β-Catenin-Dependent and -Independent Wnt Signaling.

    Science.gov (United States)

    Kling, Jessica C; Jordan, Margaret A; Pitt, Lauren A; Meiners, Jana; Thanh-Tran, Thao; Tran, Le Son; Nguyen, Tam T K; Mittal, Deepak; Villani, Rehan; Steptoe, Raymond J; Khosrotehrani, Kiarash; Berzins, Stuart P; Baxter, Alan G; Godfrey, Dale I; Blumenthal, Antje

    2018-01-01

    Natural killer T (NKT) cells are prominent innate-like lymphocytes in the liver with critical roles in immune responses during infection, cancer, and autoimmunity. Interferon gamma (IFN-γ) and IL-4 are key cytokines rapidly produced by NKT cells upon recognition of glycolipid antigens presented by antigen-presenting cells (APCs). It has previously been reported that the transcriptional coactivator β-catenin regulates NKT cell differentiation and functionally biases NKT cell responses toward IL-4, at the expense of IFN-γ production. β-Catenin is not only a central effector of Wnt signaling but also contributes to other signaling networks. It is currently unknown whether Wnt ligands regulate NKT cell functions. We thus investigated how Wnt ligands and β-catenin activity shape liver NKT cell functions in vivo in response to the glycolipid antigen, α-galactosylceramide (α-GalCer) using a mouse model. Pharmacologic targeting of β-catenin activity with ICG001, as well as myeloid-specific genetic ablation of Wntless (Wls) , to specifically target Wnt protein release by APCs, enhanced early IFN-γ responses. By contrast, within several hours of α-GalCer challenge, myeloid-specific Wls deficiency, as well as pharmacologic targeting of Wnt release using the small molecule inhibitor IWP-2 impaired α-GalCer-induced IFN-γ responses, independent of β-catenin activity. These data suggest that myeloid cell-derived Wnt ligands drive early Wnt/β-catenin signaling that curbs IFN-γ responses, but that, subsequently, Wnt ligands sustain IFN-γ expression independent of β-catenin activity. Our analyses in ICG001-treated mice confirmed a role for β-catenin activity in driving early IL-4 responses by liver NKT cells. However, neither pharmacologic nor genetic perturbation of Wnt production affected the IL-4 response, suggesting that IL-4 production by NKT cells in response to α-GalCer is not driven by released Wnt ligands. Collectively, these data reveal complex temporal

  9. Temporal Regulation of Natural Killer T Cell Interferon Gamma Responses by β-Catenin-Dependent and -Independent Wnt Signaling

    Directory of Open Access Journals (Sweden)

    Jessica C. Kling

    2018-03-01

    Full Text Available Natural killer T (NKT cells are prominent innate-like lymphocytes in the liver with critical roles in immune responses during infection, cancer, and autoimmunity. Interferon gamma (IFN-γ and IL-4 are key cytokines rapidly produced by NKT cells upon recognition of glycolipid antigens presented by antigen-presenting cells (APCs. It has previously been reported that the transcriptional coactivator β-catenin regulates NKT cell differentiation and functionally biases NKT cell responses toward IL-4, at the expense of IFN-γ production. β-Catenin is not only a central effector of Wnt signaling but also contributes to other signaling networks. It is currently unknown whether Wnt ligands regulate NKT cell functions. We thus investigated how Wnt ligands and β-catenin activity shape liver NKT cell functions in vivo in response to the glycolipid antigen, α-galactosylceramide (α-GalCer using a mouse model. Pharmacologic targeting of β-catenin activity with ICG001, as well as myeloid-specific genetic ablation of Wntless (Wls, to specifically target Wnt protein release by APCs, enhanced early IFN-γ responses. By contrast, within several hours of α-GalCer challenge, myeloid-specific Wls deficiency, as well as pharmacologic targeting of Wnt release using the small molecule inhibitor IWP-2 impaired α-GalCer-induced IFN-γ responses, independent of β-catenin activity. These data suggest that myeloid cell-derived Wnt ligands drive early Wnt/β-catenin signaling that curbs IFN-γ responses, but that, subsequently, Wnt ligands sustain IFN-γ expression independent of β-catenin activity. Our analyses in ICG001-treated mice confirmed a role for β-catenin activity in driving early IL-4 responses by liver NKT cells. However, neither pharmacologic nor genetic perturbation of Wnt production affected the IL-4 response, suggesting that IL-4 production by NKT cells in response to α-GalCer is not driven by released Wnt ligands. Collectively, these data reveal

  10. Analysis of Transcriptional Signatures in Response to Listeria monocytogenes Infection Reveals Temporal Changes That Result from Type I Interferon Signaling

    Science.gov (United States)

    Potempa, Krzysztof; Graham, Christine M.; Moreira-Teixeira, Lucia; McNab, Finlay W.; Howes, Ashleigh; Stavropoulos, Evangelos; Pascual, Virginia; Banchereau, Jacques; Chaussabel, Damien; O’Garra, Anne

    2016-01-01

    Analysis of the mouse transcriptional response to Listeria monocytogenes infection reveals that a large set of genes are perturbed in both blood and tissue and that these transcriptional responses are enriched for pathways of the immune response. Further we identified enrichment for both type I and type II interferon (IFN) signaling molecules in the blood and tissues upon infection. Since type I IFN signaling has been reported widely to impair bacterial clearance we examined gene expression from blood and tissues of wild type (WT) and type I IFNαβ receptor-deficient (Ifnar1-/-) mice at the basal level and upon infection with L. monocytogenes. Measurement of the fold change response upon infection in the absence of type I IFN signaling demonstrated an upregulation of specific genes at day 1 post infection. A less marked reduction of the global gene expression signature in blood or tissues from infected Ifnar1-/- as compared to WT mice was observed at days 2 and 3 after infection, with marked reduction in key genes such as Oasg1 and Stat2. Moreover, on in depth analysis, changes in gene expression in uninfected mice of key IFN regulatory genes including Irf9, Irf7, Stat1 and others were identified, and although induced by an equivalent degree upon infection this resulted in significantly lower final gene expression levels upon infection of Ifnar1-/- mice. These data highlight how dysregulation of this network in the steady state and temporally upon infection may determine the outcome of this bacterial infection and how basal levels of type I IFN-inducible genes may perturb an optimal host immune response to control intracellular bacterial infections such as L. monocytogenes. PMID:26918359

  11. Non-autonomous bifurcation in impulsive systems

    Directory of Open Access Journals (Sweden)

    Marat Akhmet

    2013-12-01

    Full Text Available This is the first paper which considers non-autonomous bifurcations in impulsive differential equations. Impulsive generalizations of the non-autonomous pitchfork and transcritical bifurcation are discussed. We consider scalar differential equation with fixed moments of impulses. It is illustrated by means of certain systems how the idea of pullback attracting sets remains a fruitful concept in the impulsive systems. Basics of the theory are provided.

  12. Temporal code in the vibrissal system - Part I: Vibrissa response to passive stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Farfan, F D [Departamento de BioingenierIa, FACET, Universidad Nacional de Tucuman, INSIBIO - CONICET, CC 327, Postal Code CP, 4000 (Argentina); AlbarracIn, A L [Catedra de Neurociencias, Facultad de Medicina, Universidad Nacional de Tucuman (Argentina); Felice, C J [Departamento de BioingenierIa, FACET, Universidad Nacional de Tucuman, INSIBIO - CONICET, CC 327, Postal Code CP, 4000 (Argentina)

    2007-11-15

    In this paper we analyzed the afferent discharges of two nerves: one innervating three vibrissae (N1) and another one innervating the DELTA vibrissa (N2). Sustained mechanical stimulations were applied to the hair shaft of a whisker innervated by N1 in three different directions. The vibrissa selected for stimulation was the one that produced the higher electrical activity in the N1. The vibrissa was bent 1, 2 and 3 mm in each direction. The manual stimulation was applied to DELTA vibrissa and its electrical activity was registered. A custom-made photoresistive sensor registered the vibrissa displacements. We analyzed the multifiber discharge with a spike detection algorithm using the continuous wavelet transform (CWT). Directional sensibility in afferent responses was observed. RMS values had higher sensibility to deflection intensity in direction 1, while the responses in direction 2 and 3 were different. Median and dispersion of the inter-event times were decreased during different levels of the bent (events of 0.2 msec). The statistical analysis of the inter-event times showed significant differences among different stimulation levels. The inter-event times are decreased during passive movement with bent quantity induced to DELTA vibrissa. In this case the events duration was 0.6 ms.

  13. Francisella tularensis subsp. tularensis induces a unique pulmonary inflammatory response: role of bacterial gene expression in temporal regulation of host defense responses.

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    Kathie-Anne Walters

    Full Text Available Pulmonary exposure to Francisella tularensis is associated with severe lung pathology and a high mortality rate. The lack of induction of classical inflammatory mediators, including IL1-β and TNF-α, during early infection has led to the suggestion that F. tularensis evades detection by host innate immune surveillance and/or actively suppresses inflammation. To gain more insight into the host response to Francisella infection during the acute stage, transcriptomic analysis was performed on lung tissue from mice exposed to virulent (Francisella tularensis ssp tularensis SchuS4. Despite an extensive transcriptional response in the lungs of animals as early as 4 hrs post-exposure, Francisella tularensis was associated with an almost complete lack of induction of immune-related genes during the initial 24 hrs post-exposure. This broad subversion of innate immune responses was particularly evident when compared to the pulmonary inflammatory response induced by other lethal (Yersinia pestis and non-lethal (Legionella pneumophila, Pseudomonas aeruginosa pulmonary infections. However, the unique induction of a subset of inflammation-related genes suggests a role for dysregulation of lymphocyte function and anti-inflammatory pathways in the extreme virulence of Francisella. Subsequent activation of a classical inflammatory response 48 hrs post-exposure was associated with altered abundance of Francisella-specific transcripts, including those associated with bacterial surface components. In summary, virulent Francisella induces a unique pulmonary inflammatory response characterized by temporal regulation of innate immune pathways correlating with altered bacterial gene expression patterns. This study represents the first simultaneous measurement of both host and Francisella transcriptome changes that occur during in vivo infection and identifies potential bacterial virulence factors responsible for regulation of host inflammatory pathways.

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

    Science.gov (United States)

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

    2016-07-01

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

  15. Full averaging of fuzzy impulsive differential inclusions

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    Natalia V. Skripnik

    2010-09-01

    Full Text Available In this paper the substantiation of the method of full averaging for fuzzy impulsive differential inclusions is studied. We extend the similar results for impulsive differential inclusions with Hukuhara derivative (Skripnik, 2007, for fuzzy impulsive differential equations (Plotnikov and Skripnik, 2009, and for fuzzy differential inclusions (Skripnik, 2009.

  16. Temporal specificity of training: intra-day effects on biochemical responses and Olympic-Weightlifting performances.

    Science.gov (United States)

    Ammar, Achraf; Chtourou, Hamdi; Trabelsi, Khaled; Padulo, Johnny; Turki, Mouna; El Abed, Kais; Hoekelmann, Anitta; Hakim, Ahmed

    2015-01-01

    The aim of this study was to investigate the performance of an Olympic-Weightlifting session training at three times of the day on the performance related to biochemical responses. Nine weightlifters (21 ± 0.5 years) performed, in randomised order, on three Olympic-Weightlifting training (snatch, clean and jerk) sessions (08:00 a.m., 02:00 p. m., 06:00 p. m.). Blood samples were collected: before, 3 min and 48 h after each training session. Haematological parameters and markers of muscle injury were assessed. Resting oral temperature and rating of perceived exertion (RPE) were also assessed during each session. ANOVA showed that the performance was better (P training sessions with lower values ​​in the evening compared to the morning. In conclusion, the afternoon training is more effective than morning or evening sessions for weightlifters. Therefore, coaches and weightlifters should be advised to schedule their training session in the afternoon hour.

  17. Disentangling woodland caribou movements in response to clearcuts and roads across temporal scales.

    Directory of Open Access Journals (Sweden)

    David Beauchesne

    Full Text Available Although prey species typically respond to the most limiting factors at coarse spatiotemporal scales while addressing biological requirements at finer scales, such behaviour may become challenging for species inhabiting human altered landscapes. We investigated how woodland caribou, a threatened species inhabiting North-American boreal forests, modified their fine-scale movements when confronted with forest management features (i.e. clearcuts and roads. We used GPS telemetry data collected between 2004 and 2010 on 49 female caribou in a managed area in Québec, Canada. Movements were studied using a use--availability design contrasting observed steps (i.e. line connecting two consecutive locations with random steps (i.e. proxy of immediate habitat availability. Although caribou mostly avoided disturbances, individuals nonetheless modulated their fine-scale response to disturbances on a daily and annual basis, potentially compromising between risk avoidance in periods of higher vulnerability (i.e. calving, early and late winter during the day and foraging activities in periods of higher energy requirements (i.e. spring, summer and rut during dusk/dawn and at night. The local context in which females moved was shown to influence their decision to cross clearcut edges and roads. Indeed, although females typically avoided crossing clearcut edges and roads at low densities, crossing rates were found to rapidly increase in greater disturbance densities. In some instance, however, females were less likely to cross edges and roads as densities increased. Females may then be trapped and forced to use disturbed habitats, known to be associated with higher predation risk. We believe that further increases in anthropogenic disturbances could exacerbate such behavioural responses and ultimately lead to population level consequences.

  18. Using temporal coherence to determine the response to climate change in Boreal Shield lakes.

    Science.gov (United States)

    Arnott, Shelley E; Keller, Bill; Dillon, Peter J; Yan, Norman; Paterson, Michael; Findlay, David

    2003-01-01

    Climate change is expected to have important impacts on aquatic ecosystems. On the Boreal Shield, mean annual air temperatures are expected to increase 2 to 4 degrees C over the next 50 years. An important challenge is to predict how changes in climate and climate variability will impact natural systems so that sustainable management policies can be implemented. To predict responses to complex ecosystem changes associated with climate change, we used long-term biotic databases to evaluate how important elements of the biota in Boreal Shield lakes have responded to past fluctuations in climate. Our long-term records span a two decade period where there have been unusually cold years and unusually warm years. We used coherence analyses to test for regionally operating controls on climate, water temperature, pH, and plankton richness and abundance in three regions across Ontario: the Experimental Lakes Area, Sudbury, and Dorset. Inter-annual variation in air temperature was similar among regions, but there was a weak relationship among regions for precipitation. While air temperature was closely related to lake surface temperatures in each of the regions, there were weak relationships between lake surface temperature and richness or abundance of the plankton. However, inter-annual changes in lake chemistry (i.e., pH) were correlated with some biotic variables. In some lakes in Sudbury and Dorset, pH was dependent on extreme events. For example, El Nino related droughts resulted in acidification pulses in some lakes that influenced phytoplankton and zooplankton richness. These results suggest that there can be strong heterogeneity in lake ecosystem responses within and across regions.

  19. Impulsivity and apathy in Parkinson’s disease

    Science.gov (United States)

    Sinha, Nihal; Manohar, Sanjay; Husain, Masud

    2013-01-01

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

  20. Comparison of impulsivity in non-problem, at-risk and problem gamblers.

    Science.gov (United States)

    Yan, Wan-Sen; Zhang, Ran-Ran; Lan, Yan; Li, Yong-Hui; Sui, Nan

    2016-12-15

    As a non-substance addiction, gambling disorder represents the model for studying the neurobiology of addiction without toxic consequences of chronic drug use. From a neuropsychological perspective, impulsivity is deemed as a potential construct responsible in the onset and development of drug addiction. The objective of this study was to investigate the associations between impulsivity and gambling status in young adults with varying severity of gambling. A sample of 1120 college students, equally divided into non-problem, at-risk and problem gamblers, were administered multiple measures of impulsivity including the UPPSP Impulsive Behaviors Scale (UPPSP), the Barratt Impulsiveness Scale-11 (BIS-11), and the Delay-discounting Test (DDT). Compared with non-problem gamblers, both at-risk gamblers and problem gamblers displayed elevated scores on Negative Urgency, Positive Urgency, Motor Impulsiveness, and Attentional Impulsiveness. Problem gamblers showed higher scores than at-risk gamblers on Positive Urgency. Logistic regression models revealed that only Negative Urgency positively predicted both at-risk gambling and problem gambling compared to non-problem gambling. These results suggest that dimensions of impulsivity may be differentially linked to gambling behavior in young adults, with Negative Urgency putatively identified as an important impulsivity-related marker for the development of gambling disorder, which may provide a better understanding of the pathogenesis.

  1. Eolian sediment responses to late Quaternary climate changes: Temporal and spatial patterns in the Sahara

    Science.gov (United States)

    Swezey, C.

    2001-01-01

    This paper presents a compilation of eolian-based records of late Quaternary climate changes in the Sahara. Although the data are relatively sparse, when viewed as a whole, they reveal a general pattern of widespread eolian sediment mobilization prior to 11,000 cal. years BP, eolian sediment stabilization from 11,000 to 5000 cal. years BP, and a return to widespread eolian sediment mobilization after 5000 cal. years BP. Furthermore, an eolian-based record from southern Tunisia reveals the existence of millennial-scale changes in eolian sediment behavior. These millennial-scale variations provide examples of eolian sediment responses to climate changes at a scale intermediate between seasonal and orbital ('Milankovitch') changes, and they are also coincident with abrupt atmospheric and oceanic changes. The general synchroneity of the eolian stratigraphic records and their coincidence with various oceanic and atmospheric changes suggest that global forcing mechanisms have influenced late Quaternary eolian sediment behavior in the Sahara. ?? 2001 Elsevier Science B.V.

  2. Stoichiometric homeostasis predicts plant species dominance, temporal stability, and responses to global change.

    Science.gov (United States)

    Yu, Qiang; Wilcox, Kevin; La Pierre, Kimberly; Knapp, Alan K; Han, Xingguo; Smith, Melinda D

    2015-09-01

    Why some species are consistently more abundant than others, and predicting how species will respond to global change, are fundamental questions in ecology. Long-term observations indicate that plant species with high stoichiometric homeostasis for nitrogen (HN), i.e., the ability to decouple foliar N levels from variation in soil N availability, were more common and stable through time than low-HN species in a central U.S. grassland. However, with nine years of nitrogen addition, species with high H(N) decreased in abundance, while those with low H(N) increased in abundance. In contrast, in climate change experiments simulating a range of forecast hydrologic changes, e.g., extreme drought (two years), increased rainfall variability (14 years), and chronic increases in rainfall (21 years), plant species with the highest H(N) were least responsive to changes in soil water availability. These results suggest that H(N) may be predictive of plant species success and stability, and how plant species and ecosystems will respond to global-change-driven alterations in resource availability.

  3. Temporal acclimation of Microchloropsis gaditana CCMP526 in response to hypersalinity.

    Science.gov (United States)

    Karthikaichamy, Anbarasu; Deore, Pranali; Srivastava, Sanjeeva; Coppel, Ross; Bulach, Dieter; Beardall, John; Noronha, Santosh

    2018-04-01

    Evaporation from culture ponds and raceways can subject algae to hypersalinity stress, and this is exacerbated by global warming. We investigated the effect of salinity on a marine microalga, Microchloropsis gaditana, which is of industrial significance because of its high lipid-accumulating capability. Both short-term (hours) and medium-term (days) effects of salinity were studied across various salinities (37.5, 55, 70 and 100 PSU). Salinity above 55 PSU suppressed cell growth and specific growth rate was significantly reduced at 100 PSU. Photosynthesis (F v /F m , rETR max and I k ) was severely affected at high salinity conditions. Total carbohydrate per cell increased ∼1.7-fold after 24 h, which is consistent with previous findings that salinity induces osmolyte production to counter osmotic shock. In addition, accumulation of lipid increased by ∼4.6-fold in response to salinity. Our findings indicate a possible mechanism of acclimation to salinity, opening up new frontiers for osmolytes in pharmacological and cosmetics applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. THz impulse radar for biomedical sensing: nonlinear system behavior

    Science.gov (United States)

    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.

  5. Temporal changes in the granulocytic responses to experimental infection of the skin of mice and sheep with Dermatophilus congolensis.

    Science.gov (United States)

    Lloyd, D H; Sasiak, A B; Kitson, S; McEwan Jenkinson, D; Elder, H Y

    1993-01-01

    The patterns of dermal inflammatory cell response to infection with Dermatophilosis congolensis were determined in mice and sheep from histological samples taken before and at intervals after topical application of infective zoospores to ether-swabbed skin. Neutrophils, eosinophils, basophils and mast cells were identified by histochemical staining. Temporal changes in the B cell, T cell, and MHC Class II+ dendritic cell populations form part of a separate report. The filamentous stages of the bacterium were observed in the stratum corneum of both species; in the sheep they were also found in the outer layers of the living epidermis. In both species, large numbers of neutrophils and some lymphocytes penetrated the epidermis and entered the infected surface region. Within the underlying dermis there was an accumulation of dendritic cells immediately below the infected epidermis and evidence of mast cell degranulation; the basophils and eosinophils did not appear to be actively involved. The striking difference between the two species was the duration of the infection and the associated response which, in the mouse, lasted about five days in comparison with over 21 days in the sheep. Neutrophil numbers in the mouse for example were elevated by 12 h and had peaked at 60 h after infection, while in the sheep they did not peak until about 120 h.

  6. Temporal response properties of retinal ganglion cells in rd1 mice evoked by amplitude-modulated electrical pulse trains.

    Science.gov (United States)

    Ryu, Sang Baek; Ye, Jang Hee; Goo, Yong Sook; Kim, Chi Hyun; Kim, Kyung Hwan

    2010-12-01

    The electrophysiological properties of degenerated retinas responding to amplitude-modulated electrical pulse trains were investigated to provide a guideline for the development of a stimulation strategy for retinal prostheses. The activities of retinal ganglion cells (RGCs) in response to amplitude-modulated pulse trains were recorded from an in vitro model of retinal prosthesis, which consisted of an rd1 mouse retinal patch attached to a planar multielectrode array. The ability of the population activities of RGCs to effectively represent, or encode, the information on the visual intensity time series, when the intensity of visual input is transformed to pulse amplitudes, was investigated. An optimal pulse amplitude range was selected so that RGC firing rates increased monotonically and linearly. An approximately 10-Hz rhythm was observed in the field potentials from degenerated retinas, which resulted in a rhythmic burst of spontaneous spikes. Multiple peaks were present in poststimulus time histograms, with interpeak intervals corresponding to the oscillation frequency of the field potentials. Phase resetting of the field potential oscillation by stimulation was consistently observed. Despite a prominent alteration of the properties of electrically evoked firing with respect to normal retinas, RGC response strengths could be modulated by pulse amplitude. Accordingly, the temporal information of stimulation could be faithfully represented in the RGC firing patterns by an amplitude-modulated pulse train. The results suggest that pulse amplitude modulation is a feasible means of implementing a stimulation strategy for retinal prostheses, despite the marked change in the physiological properties of RGCs in degenerated retinas.

  7. The insular cortex: relationship to skin conductance responses to facial expression of emotion in temporal lobe epilepsy.

    Science.gov (United States)

    Banks, Sarah J; Bellerose, Jenny; Douglas, Danielle; Jones-Gotman, Marilyn

    2014-03-01

    The insula plays an important role both in emotion processing and in the generation of epileptic seizures. In the current study we examined thickness of insular cortices and bilateral skin conductance responses (SCR) in healthy subjects in addition to a small number of patients with temporal lobe epilepsy. SCR measures arousal and is used to assess non-conscious responses to emotional stimuli. We used two emotion tasks, one explicitly about emotion and the other implicit. The explicit task required judgments about emotions being expressed in photographs of faces, while the implicit one required judgments about the age of the people in the photographs. Patients and healthy differed in labeling neutral faces, but not other emotions. They also differed in their SCR to emotions, though the profile depended on which hand the recordings were from. Finally, we found relationships between the thickness of the insula and SCR to each task: in the healthy group the thickness of the left insula was related to SCR to the emotion-labeling task; in the patient group it was between the thickness of the right insula and SCR in the age-labeling task. These patterns were evident only for the right hand recordings, thus underscoring the importance of bilateral recordings.

  8. Temporal water quality response in an urban river: a case study in peninsular Malaysia

    Science.gov (United States)

    VishnuRadhan, Renjith; Zainudin, Zaki; Sreekanth, G. B.; Dhiman, Ravinder; Salleh, Mohd. Noor; Vethamony, P.

    2017-05-01

    Ambient water quality is a prerequisite for the health and self-purification capacity of riverine ecosystems. To understand the general water quality situation, the time series data of selected water quality parameters were analyzed in an urban river in Peninsular Malaysia. In this regard, the stations were selected from the main stem of the river as well as from the side channel. The stations located at the main stem of the river are less polluted than that in the side channel. Water Quality Index scores indicated that the side channel station is the most polluted, breaching the Class IV water quality criteria threshold during the monitoring period, followed by stations at the river mouth and the main channel. The effect of immediate anthropogenic waste input is also evident at the side channel station. The Organic Pollution Index of side channel station is (14.99) 3 times higher than at stations at river mouth (4.11) and 6 times higher than at the main channel (2.57). The two-way ANOVA showed significant difference among different stations. Further, the factor analysis on water quality parameters yielded two significant factors. They discriminated the stations into two groups. The land-use land cover classification of the study area shows that the region near the sampling sites is dominated by urban settlements (33.23 %) and this can contribute significantly to the deterioration of ambient river water quality. The present study estimated the water quality condition and response in the river and the study can be an immediate yardstick for base lining river water quality, and a basis for future water quality modeling studies in the region.

  9. Temporal Response of Angiogenesis and Hypertrophy to Resistance Training in Young Men.

    Science.gov (United States)

    Holloway, Tanya M; Snijders, Tim; VAN Kranenburg, Janneau; VAN Loon, Luc J C; Verdijk, Lex B

    2018-01-01

    Although endurance exercise training promotes angiogenesis and improves metabolic health, the effect of resistance training on this process is less well defined. We hypothesized that capillarization would increase proportionally, and concurrently, with muscle fiber hypertrophy in response to resistance training in young men. In this double-blind, randomized control trial, 36 men (22 ± 1 yr) were randomized to placebo or protein supplementation, and participated in 12 wk of resistance training. Skeletal muscle biopsies were collected before and after 2, 4, 8, and 12 wk of training. Immunohistochemistry assessed fiber type-specific size and capillarization. Western blot and reverse transcription polymerase chain reaction assessed proteins involved in the molecular regulation of angiogenesis. Resistance training effectively increased Type I (15% ± 4%; P < 0.01) and Type II fiber cross-sectional area (28% ± 5%; P < 0.0001), an effect that tended to be further enhanced with protein supplementation in Type II fibers (P = 0.078). Capillary-to-fiber ratio significantly increased in Type I (P = 0.001) and II (P = 0.015) fibers after 12 wk of resistance exercise training and was evident after only 2 wk. Capillary-to-fiber perimeter exchange index increased in the Type I fibers only (P = 0.054) after 12 wk of training. Training resulted in a reduction in vascular endothelial growth factor mRNA. A (P = 0.008), while vascular endothelial growth factor receptor 2 (P = 0.016), hypoxia-inducible factor 1α (P = 0.016), and endothelial nitric oxide synthase (P = 0.01) increased in both groups. Hypoxia-inducible factor 1α protein content was higher in the protein group (main group effect, P = 0.02), and endothelial nitric oxide synthase content demonstrated a divergent relationship (time-group interaction, P = 0.049). This study presents novel evidence that microvascular adaptations and the molecular pathways involved are elevated after 2 wk of a 12-wk resistance training

  10. Imaging the Spatio-Temporal Dynamics of Supragranular Activity in the Rat Somatosensory Cortex in Response to Stimulation of the Paws

    Science.gov (United States)

    Morales-Botello, M. L.; Aguilar, J.; Foffani, G.

    2012-01-01

    We employed voltage-sensitive dye (VSD) imaging to investigate the spatio-temporal dynamics of the responses of the supragranular somatosensory cortex to stimulation of the four paws in urethane-anesthetized rats. We obtained the following main results. (1) Stimulation of the contralateral forepaw evoked VSD responses with greater amplitude and smaller latency than stimulation of the contralateral hindpaw, and ipsilateral VSD responses had a lower amplitude and greater latency than contralateral responses. (2) While the contralateral stimulation initially activated only one focus, the ipsilateral stimulation initially activated two foci: one focus was typically medial to the focus activated by contralateral stimulation and was stereotaxically localized in the motor cortex; the other focus was typically posterior to the focus activated by contralateral stimulation and was stereotaxically localized in the somatosensory cortex. (3) Forepaw and hindpaw somatosensory stimuli activated large areas of the sensorimotor cortex, well beyond the forepaw and hindpaw somatosensory areas of classical somatotopic maps, and forepaw stimuli activated larger cortical areas with greater activation velocity than hindpaw stimuli. (4) Stimulation of the forepaw and hindpaw evoked different cortical activation dynamics: forepaw responses displayed a clear medial directionality, whereas hindpaw responses were much more uniform in all directions. In conclusion, this work offers a complete spatio-temporal map of the supragranular VSD cortical activation in response to stimulation of the paws, showing important somatotopic differences between contralateral and ipsilateral maps as well as differences in the spatio-temporal activation dynamics in response to forepaw and hindpaw stimuli. PMID:22829873

  11. ESTIMATION OF IMPULSE RESPONSE FUNCTION BY ...

    African Journals Online (AJOL)

    Global Journal of Mathematical Sciences. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 3, No 1 (2004) >. Log in or Register to get access to full text downloads.

  12. Impulse Force Balance for Ultrashort Duration Hypersonic Test Facilities

    Directory of Open Access Journals (Sweden)

    P. Singh

    2015-01-01

    Full Text Available This paper presents the measurement of side force, pitching, and yawing moments on a model, using an accelerometer force balance, in a short duration hypersonic shock tunnel. The test model is a blunt-nosed, flapped delta wing, mounted on a support sting through a force balance. The flexible rubber bushes constituting the balance allow the model to float freely on the sting during the test. The accelerometers were located in the model to record accelerations in the directions of interest. The model was tested in shock tunnel at Mach 8 at different angles of incidence with the freestream. Dynamic calibration of the test assembly was carried out for the acquisition of impulse response functions for the above components of force and moments, using an impulse hammer. The convolution technique was applied to derive the impulse response functions. The accelerometer outputs from the model in the hypersonic freestream were processed using the respective impulse response functions to derive the unknown aerodynamic force and moments. The newly adopted convolution technique has been found very effective for data reduction from accelerometer force balances developed for shock tunnel applications.

  13. Internal and external generalizability of temporal dose-response relationships for xerostomia following IMRT for head and neck cancer.

    Science.gov (United States)

    Thor, Maria; Owosho, Adepitan A; Clark, Haley D; Oh, Jung Hun; Riaz, Nadeem; Hovan, Allan; Tsai, Jillian; Thomas, Steven D; Yom, Sae Hee K; Wu, Jonn S; Huryn, Joseph M; Moiseenko, Vitali; Lee, Nancy Y; Estilo, Cherry L; Deasy, Joseph O

    2017-02-01

    To study internal and external generalizability of temporal dose-response relationships for xerostomia after intensity-modulated radiotherapy (IMRT) for head and neck cancer, and to investigate potential amendments of the QUANTEC guidelines. Objective xerostomia was assessed in 121 patients (n Cohort1 =55; n Cohort2 =66) treated to 70Gy@2Gy in 2006-2015. Univariate and multivariate analyses (UVA, MVA with 1000 bootstrap populations) were conducted in Cohort1, and generalizability of the best-performing MVA model was investigated in Cohort2 (performance: AUC, p-values, and Hosmer-Lemeshow p-values (p HL )). Ultimately and for clinical guidance, minimum mean dose thresholds to the contralateral and the ipsilateral parotid glands (Dmean contra , Dmean ipsi ) were estimated from the generated dose-response curves. The observed xerostomia rate was 38%/47% (3months) and 19%/23% (11-12months) in Cohort1/Cohort2. Risk of xerostomia at 3months increased for higher Dmean contra and Dmean ipsi (Cohort1: 0.17·Dmean contra +0.11·Dmean ipsi -8.13; AUC=0.90±0.05; p=0.0002±0.002; p HL =0.22±0.23; Cohort2: AUC=0.81; pxerostomia following IMRT. Our results also suggest decreasing Dmean contra to below 20Gy, while keeping Dmean ipsi to around 25Gy. Long-term xerostomia was less frequent, and no dose-response relationship was established for this follow-up time. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  14. Course of multi-impulsive bulimia.

    Science.gov (United States)

    Fichter, M M; Quadflieg, N; Rief, W

    1994-08-01

    Thirty-two consecutively admitted females with bulimia nervosa (purging type) according to DSM-IV and additional impulsive behaviours (multi-impulsive bulimia (MIB)) and 32 age-matched female controls with DSM-IV bulimia nervosa (purging type) (uni-impulsive bulimia (UIB)) were assessed longitudinally on admission and at discharge following in-patient therapy and at a 2-year follow-up. Multi-impulsive bulimics were defined as presenting at least three of the six of the following impulsive behaviours in their life-time in addition to their bulimic symptoms at admission: (a) suicidal attempts, (b) severe autoaggression, (c) shop lifting (other than food), (d) alcohol abuse, (e) drug abuse, or (f) sexual promiscuity. Multi-impulsive bulimics were more frequently separated or divorced, had less schooling and held less-skilled jobs. Except for interoceptive awareness (EDI), which was more disturbed in multi-impulsive bulimics, there were no differences concerning scales measuring eating disturbances and related areas. Multi-impulsive bulimics showed more general psychopathology--anxiety, depression, anger and hostility, psychoticism--differed in several personality scales from uni-impulsive bulimics (e.g. increased excitability and anger/hostility) and had overall a less favourable course of illness. Multi-impulsive bulimics also received more in- and out-patient therapy previous to the index treatment and during the follow-up period. The data support the notion that 'multi-impulsive bulimia' or 'multi-impulsive disorder' should be classified as a distinct diagnostic group on axis I or that an 'Impulsive Personality Disorder' should be introduced on axis II. The development of more effective treatment for multi-impulsive bulimia is warranted.

  15. Optimal plant water use across temporal scales: bridging eco-hydrological theories and plant eco-physiological responses

    Science.gov (United States)

    Manzoni, S.; Vico, G.; Palmroth, S.; Katul, G. G.; Porporato, A. M.

    2013-12-01

    In terrestrial ecosystems, plant photosynthesis occurs at the expense of water losses through stomata, thus creating an inherent hydrologic constrain to carbon (C) gains and productivity. While such a constraint cannot be overcome, evolution has led to a number of adaptations that allow plants to thrive under highly variable and often limiting water availability. It may be hypothesized that these adaptations are optimal and allow maximum C gain for a given water availability. A corollary hypothesis is that these adaptations manifest themselves as coordination between the leaf photosynthetic machinery and the plant hydraulic system. This coordination leads to functional relations between the mean hydrologic state, plant hydraulic traits, and photosynthetic parameters that can be used as bridge across temporal scales. Here, optimality theories describing the behavior of stomata and plant morphological features in a fluctuating soil moisture environment are proposed. The overarching goal is to explain observed global patterns of plant water use and their ecological and biogeochemical consequences. The problem is initially framed as an optimal control problem of stomatal closure during drought of a given duration, where maximizing the total photosynthesis under limited and diminishing water availability is the objective function. Analytical solutions show that commonly used transpiration models (in which stomatal conductance is assumed to depend on soil moisture) are particular solutions emerging from the optimal control problem. Relations between stomatal conductance, vapor pressure deficit, and atmospheric CO2 are also obtained without any a priori assumptions under this framework. Second, the temporal scales of the model are expanded by explicitly considering the stochasticity of rainfall. In this context, the optimal control problem becomes a maximization problem for the mean photosynthetic rate. Results show that to achieve maximum C gains under these

  16. Mathematical modelling of the spatio-temporal response of cytotoxic T-lymphocytes to a solid tumour.

    Science.gov (United States)

    Matzavinos, Anastasios; Chaplain, Mark A J; Kuznetsov, Vladimir A

    2004-03-01

    In this paper a mathematical model describing the growth of a solid tumour in the presence of an immune system response is presented. In particular, attention is focused upon the attack of tumour cells by so-called tumour-infiltrating cytotoxic lymphocytes (TICLs), in a small, multicellular tumour, without necrosis and at some stage prior to (tumour-induced) angiogenesis. At this stage the immune cells and the tumour cells are considered to be in a state of dynamic equilibrium--cancer dormancy--a phenomenon which has been observed in primary tumours, micrometastases and residual disease after ablation of the primary tumour. Nonetheless, the precise biochemical and cellular mechanisms by which TICLs control cancer dormancy are still poorly understood from a biological and immunological point of view. Therefore we focus on the analysis of the spatio-temporal dynamics of tumour cells, immune cells and chemokines in an immunogenic tumour. The lymphocytes are assumed to migrate into the growing solid tumour and interact with the tumour cells in such a way that lymphocyte-tumour cell complexes are formed. These complexes result in either the death of the tumour cells (the normal situation) or the inactivation (sometimes even the death) of the lymphocytes. The migration of the TICLs is determined by a combination of random motility and chemotaxis in response to the presence of chemokines. The resulting system of four nonlinear partial differential equations (TICLs, tumour cells, complexes and chemokines) is analysed and numerical simulations are presented. We consider two different tumour geometries--multi-layered cell growth and multi-cellular spheroid growth. The numerical simulations demonstrate the existence of cell distributions that are quasi-stationary in time and heterogeneous in space. A linear stability analysis of the underlying (spatially homogeneous) ordinary differential equation (ODE) kinetics coupled with a numerical investigation of the ODE system reveals

  17. Spatial and Temporal Characterization of Indoor Millimeter Wave Propagation at 24 GHz

    OpenAIRE

    Seok-hwan Min; Hayeon Kim; Haengseon Lee; Woo Jin Byun; Minsoo Kang; Kwangseon Kim; Bong-su Kim; Myung-sun Song

    2016-01-01

    Indoor millimeter wave propagation at the frequency of 24 GHz is studied by experimental methods. Measurements are performed to obtain temporal and spatial channel model using a channel sounder and rotating antennas in a corridor. The measured impulse responses are processed to obtain compact channel model following Saleh-Valenzuela’s model. The responses are compared with those of 5.3 GHz for the same test sites. Angular spread of 24 GHz is found to be smaller than that of 5.3 GHz, while ech...

  18. Evaluating the impact of spatio-temporal smoothness constraints on the BOLD hemodynamic response function estimation: an analysis based on Tikhonov regularization

    International Nuclear Information System (INIS)

    Casanova, R; Yang, L; Hairston, W D; Laurienti, P J; Maldjian, J A

    2009-01-01

    Recently we have proposed the use of Tikhonov regularization with temporal smoothness constraints to estimate the BOLD fMRI hemodynamic response function (HRF). The temporal smoothness constraint was imposed on the estimates by using second derivative information while the regularization parameter was selected based on the generalized cross-validation function (GCV). Using one-dimensional simulations, we previously found this method to produce reliable estimates of the HRF time course, especially its time to peak (TTP), being at the same time fast and robust to over-sampling in the HRF estimation. Here, we extend the method to include simultaneous temporal and spatial smoothness constraints. This method does not need Gaussian smoothing as a pre-processing step as usually done in fMRI data analysis. We carried out two-dimensional simulations to compare the two methods: Tikhonov regularization with temporal (Tik-GCV-T) and spatio-temporal (Tik-GCV-ST) smoothness constraints on the estimated HRF. We focus our attention on quantifying the influence of the Gaussian data smoothing and the presence of edges on the performance of these techniques. Our results suggest that the spatial smoothing introduced by regularization is less severe than that produced by Gaussian smoothing. This allows more accurate estimates of the response amplitudes while producing similar estimates of the TTP. We illustrate these ideas using real data. (note)

  19. Temporal and Spatial Variations of Vegetation Cover in Xinjiang from 2002 to 2015 and Their Response to Climate

    Science.gov (United States)

    Liu, S. S.; Zhang, Q.; Li, X. C.; Song, W. J.; Yang, J. N.; Liu, X. J.

    2017-07-01

    In this paper, the dataset of normalized difference vegetation indexes (NDVIs) in the arid region in Xinjiang from 2002 to 2015 as well as the climate data from 52 meteorological stations are utilized and the temporal and spatial variations of NDVI in recent years and their response to temperature and precipitation are analyzed in combination with various methods such as the maximum value analysis, correlation analysis and spatial analysis. It is concluded that in the past 14 years, the annual maximum NDVIs of Xinjiang presented a moderate rising tendency; Under the influence of the global background, the temperature and precipitation also showed different degrees of increase, which showed a significant increase in temperature. The annual maximum NDVI had a significant correlation with the annual precipitation (correlation coefficient: 0.634), but no obvious correlation was identified between the annual maximum NDVI and the annual average temperature (correlation coefficient: 0.279). To this end, regarding to the climatic factors, the influence of precipitation on the vegetation cover is higher than that of temperature.

  20. Temporally Diverse Excitation Generates Direction-Selective Responses in ON- and OFF-Type Retinal Starburst Amacrine Cells.

    Science.gov (United States)

    Fransen, James W; Borghuis, Bart G

    2017-02-07

    The complexity of sensory receptive fields increases from one synaptic stage to the next. In many cases, increased complexity is achieved through spatiotemporal interactions between convergent excitatory and inhibitory inputs. Here, we present evidence that direction selectivity (DS), a complex emergent receptive field property of retinal starburst amacrine cells (SACs), is generated by spatiotemporal interactions between functionally diverse excitatory inputs. Electrophysiological whole-cell recordings from ON and OFF SACs show distinct temporal differences in excitation following proximal compared with distal stimulation of their receptive fields. Distal excitation is both faster and more transient, ruling out passive filtering by the dendrites and indicating a task-specific specialization. Model simulations demonstrate that this specific organization of excitation generates robust DS responses in SACs, consistent with elementary motion detector models. These results indicate that selective integration of spatiotemporally patterned excitation is a computational mechanism for motion detection in the mammalian retina. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  1. A Proposed Study Examining Individual Differences in Temporal Profiles of Cardiovascular Responses to Head Down Tilt During Fluid Loading

    Science.gov (United States)

    Cowings, Patricia; Toscano, William; Winther, Sean; Martinez, Jacqueline; Dominguez, Margaret

    2012-01-01

    Susceptibility of healthy astronauts to orthostatic hypotension and presyncope is exacerbated upon return from spaceflight. The effect of altered gravity during space flight and planetary transition on human cardiovascular function is of critical importance to maintenance of astronaut health and safety. Hypovolemia, reduced plasma volume, is suspected to play an important role in cardiovascular deconditioning following exposure to spaceflight, which may lead to increased peripheral resistance, attenuated arterial baroreflex, and changes in cardiac function. A promising countermeasure for post-flight orthostatic intolerance is fluid loading used to restore lost plasma volume by giving crew salt tablets and water prior to re-entry. The main purpose of the proposed study is to define the temporal profile of cardiac responses to simulated 0-G conditions before and following a fluid loading countermeasure. 8 men and 8 women will be tested during 4 hour exposures at 6o head down tilt (HDT). Each subject will be given two exposures to HDT on separate days, one with and one without fluid loading (one liter of 0.9% saline solution). Stand tests (orthostatic stress) will be done before and after each HDT. Cardiac measures will be obtained with both impedance cardiography and echo ultrasound

  2. Spatio-temporal brain dynamics in a combined stimulus-stimulus and stimulus-response conflict task.

    Science.gov (United States)

    Frühholz, Sascha; Godde, Ben; Finke, Mareike; Herrmann, Manfred

    2011-01-01

    It is yet not well known whether different types of conflicts share common or rely on distinct brain mechanisms of conflict processing. We used a combined Flanker (stimulus-stimulus; S-S) and Simon (stimulus-response; S-R) conflict paradigm both in an fMRI and an EEG study. S-S conflicts induced stronger behavioral interference effects compared to S-R conflicts and the latter decayed with increasing response latencies. Besides some similar medial frontal activity across all conflict trials, which was, however, not statically consistent across trials, we especially found distinct activations depending on the type of conflict. S-S conflicts activated the anterior cingulate cortex and modulated the N2 and early P3 component with underlying source activity in inferior frontal cortex. S-R conflicts produced distinct activations in the posterior cingulate cortex and modulated the late P3b component with underlying source activity in superior parietal cortex. Double conflict trials containing both S-S and S-R conflicts revealed, first, distinct anterior frontal activity representing a meta-processing unit and, second, a sequential modulation of the N2 and the P3b component. The N2 modulation during double conflict trials was accompanied by increased source activity in the medial frontal gyrus (MeFG). In summary, S-S and S-R conflict processing mostly rely on distinct mechanisms of conflict processing and these conflicts differentially modulate the temporal stages of stimulus processing. Copyright © 2010 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2017-05-01

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

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

    Science.gov (United States)

    Markus, C Rob; Jonkman, Lisa M

    2007-09-01

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

  5. Periodic components of hand acceleration/deceleration impulses during telemanipulation

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-01-01

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

  6. Periodic components of hand acceleration/deceleration impulses during telemanipulation

    International Nuclear Information System (INIS)

    Draper, J.V.; Handel, S.

    1994-01-01

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

  7. Temporal naturalism

    Science.gov (United States)

    Smolin, Lee

    2015-11-01

    Two people may claim both to be naturalists, but have divergent conceptions of basic elements of the natural world which lead them to mean different things when they talk about laws of nature, or states, or the role of mathematics in physics. These disagreements do not much affect the ordinary practice of science which is about small subsystems of the universe, described or explained against a background, idealized to be fixed. But these issues become crucial when we consider including the whole universe within our system, for then there is no fixed background to reference observables to. I argue here that the key issue responsible for divergent versions of naturalism and divergent approaches to cosmology is the conception of time. One version, which I call temporal naturalism, holds that time, in the sense of the succession of present moments, is real, and that laws of nature evolve in that time. This is contrasted with timeless naturalism, which holds that laws are immutable and the present moment and its passage are illusions. I argue that temporal naturalism is empirically more adequate than the alternatives, because it offers testable explanations for puzzles its rivals cannot address, and is likely a better basis for solving major puzzles that presently face cosmology and physics. This essay also addresses the problem of qualia and experience within naturalism and argues that only temporal naturalism can make a place for qualia as intrinsic qualities of matter.

  8. Characterisation of Hydrological Response to Rainfall at Multi Spatio-Temporal Scales in Savannas of Semi-Arid Australia

    Directory of Open Access Journals (Sweden)

    Ben Jarihani

    2017-07-01

    Full Text Available Rainfall is the main driver of hydrological processes in dryland environments and characterising the rainfall variability and processes of runoff generation are critical for understanding ecosystem function of catchments. Using remote sensing and in situ data sets, we assess the spatial and temporal variability of the rainfall, rainfall–runoff response, and effects on runoff coefficients of antecedent soil moisture and ground cover at different spatial scales. This analysis was undertaken in the Upper Burdekin catchment, northeast Australia, which is a major contributor of sediment and nutrients to the Great Barrier Reef. The high temporal and spatial variability of rainfall are found to exert significant controls on runoff generation processes. Rainfall amount and intensity are the primary runoff controls, and runoff coefficients for wet antecedent conditions were higher than for dry conditions. The majority of runoff occurred via surface runoff generation mechanisms, with subsurface runoff likely contributing little runoff due to the intense nature of rainfall events. MODIS monthly ground cover data showed better results in distinguishing effects of ground cover on runoff that Landsat-derived seasonal ground cover data. We conclude that in the range of moderate to large catchments (193–36,260 km2 runoff generation processes are sensitive to both antecedent soil moisture and ground cover. A higher runoff–ground cover correlation in drier months with sparse ground cover highlighted the critical role of cover at the onset of the wet season (driest period and how runoff generation is more sensitive to cover in drier months than in wetter months. The monthly water balance analysis indicates that runoff generation in wetter months (January and February is partially influenced by saturation overland flow, most likely confined to saturated soils in riparian corridors, swales, and areas of shallow soil. By March and continuing through October

  9. Optimal One Bit Time Reversal For UWB Impulse Radio In Multi-User Wireless Communications

    DEFF Research Database (Denmark)

    Nguyen, Hung Tuan

    2008-01-01

    In this paper, with the purpose of further reducing the complexity of the system, while keeping its temporal and spatial focusing performance, we investigate the possibility of using optimal one bit time reversal (TR) system for impulse radio ultra wideband multi-user wireless communications...

  10. Lateral Habenula Involvement in Impulsive Cocaine Seeking.

    Science.gov (United States)

    Zapata, Agustin; Hwang, Eun-Kyung; Lupica, Carl R

    2017-04-01

    The lateral habenula (LHb) is a brain structure receiving inputs from limbic forebrain areas and innervating major midbrain monoaminergic nuclei. Evidence indicates LHb involvement in sleep control, reward-based decision making, avoidance of punishment, and responses to stress. Additional work has established that the LHb mediates negative feedback in response to aversive events. As a hallmark of drug addiction is the inability to limit drug use despite negative consequences, we hypothesize that LHb dysfunction may have a role in the lack of control over drug seeking. Here we examine the effects of LHb inactivation in control over drug seeking in several cocaine self-administration (SA) paradigms in rats. We find that inhibition of the LHb with GABAergic agonists did not alter cocaine SA under progressive ratio or seeking/taking chained reinforcement schedules, or during punishment-induced suppression of cocaine-reinforced responding. In contrast, LHb inhibition increased cocaine seeking when the drug was not available in rats trained to discriminate its presence using an environmental cue. This effect of LHb inhibition was selective for cocaine, as it did not impair responding for sucrose reinforcement. The effect of LHb injection of GABA agonists was mimicked by intra-LHb muscarinic cholinergic (mACh) antagonist injection, and activation of mACh receptors excited a majority of LHb neurons in in vitro electrophysiology experiments. These results indicate that the LHb participates in the suppression of impulsive responding for cocaine through the activation of a cholinergic circuit, and they suggest that LHb dysfunction may contribute to impaired impulse control associated with drug addiction.

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

    Science.gov (United States)

    Yeomans, Martin R; Brace, Aaron

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Martin R Yeomans

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

  13. Three-dimensional whole-brain perfusion quantification using pseudo-continuous arterial spin labeling MRI at multiple post-labeling delays: accounting for both arterial transit time and impulse response function.

    Science.gov (United States)

    Qin, Qin; Huang, Alan J; Hua, Jun; Desmond, John E; Stevens, Robert D; van Zijl, Peter C M

    2014-02-01

    Measurement of the cerebral blood flow (CBF) with whole-brain coverage is challenging in terms of both acquisition and quantitative analysis. In order to fit arterial spin labeling-based perfusion kinetic curves, an empirical three-parameter model which characterizes the effective impulse response function (IRF) is introduced, which allows the determination of CBF, the arterial transit time (ATT) and T(1,eff). The accuracy and precision of the proposed model were compared with those of more complicated models with four or five parameters through Monte Carlo simulations. Pseudo-continuous arterial spin labeling images were acquired on a clinical 3-T scanner in 10 normal volunteers using a three-dimensional multi-shot gradient and spin echo scheme at multiple post-labeling delays to sample the kinetic curves. Voxel-wise fitting was performed using the three-parameter model and other models that contain two, four or five unknown parameters. For the two-parameter model, T(1,eff) values close to tissue and blood were assumed separately. Standard statistical analysis was conducted to compare these fitting models in various brain regions. The fitted results indicated that: (i) the estimated CBF values using the two-parameter model show appreciable dependence on the assumed T(1,eff) values; (ii) the proposed three-parameter model achieves the optimal balance between the goodness of fit and model complexity when compared among the models with explicit IRF fitting; (iii) both the two-parameter model using fixed blood T1 values for T(1,eff) and the three-parameter model provide reasonable fitting results. Using the proposed three-parameter model, the estimated CBF (46 ± 14 mL/100 g/min) and ATT (1.4 ± 0.3 s) values averaged from different brain regions are close to the literature reports; the estimated T(1,eff) values (1.9 ± 0.4 s) are higher than the tissue T1 values, possibly reflecting a contribution from the microvascular arterial blood compartment

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

    Science.gov (United States)

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

    2018-03-03

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

  15. Multidimensional impulsivity as a mediator of early life stress and alcohol dependence.

    Science.gov (United States)

    Kim, Shin Tae; Hwang, Syung Shick; Kim, Hae Won; Hwang, Eun Hee; Cho, Jaeil; Kang, Jee In; Kim, Se Joo

    2018-03-07

    Early life stress (ELS) leads to increased susceptibility to serious psychiatric problems such as alcohol dependence, but the mechanisms through which ELS affects alcohol dependence are unclear. We investigated the mediating role of multi-dimensional impulsivity in the associations between ELS and alcohol dependence. 330 male patients with alcohol dependence (mean age = 48.39) completed self-rating scales of ELS and several self-report measures of impulsivity as well as balloon analogue risk task (BART). After classifying different dimensions of impulsivity using factor analysis, structural equation modeling was conducted to test the mediation effects of impulsivity between ELS and alcohol dependence severity and social onset of hazardous drinking. Among the participants, 64.8%, 42.1% and 47.9% reported at least one episode of childhood maltreatment, sexual abuse and parental conflict, respectively. Response impulsivity-sensation seeking, reflection impulsivity and aggression partially mediated the association between ELS and severity of alcohol dependence (CFI = 0.902 and RMSEA = 0.079). Reflection impulsivity dimension partially mediated the association between ELS and social onset of hazardous drinking (CFI = 0.939, RMSEA = 0.091). These finding imply that stabilizing vulnerabilities such as reflection impulsivity via intervention programs that target young individuals with ELS may be helpful in delaying the onset of hazardous drinking and prevent alcohol dependence.

  16. Differential relationships between sub-traits of BIS-11 impulsivity and executive processes: an ERP study.

    Science.gov (United States)

    Kam, Julia W Y; Dominelli, Rachelle; Carlson, Scott R

    2012-08-01

    There is mixed evidence for a relationship between impulsivity and executive functions. Although impulsivity is heterogeneous, previous research did not examine partial relationships controlling for shared variance across sub-traits to evaluate the specificity of these associations. Eighty-five undergraduates completed the Barratt Impulsiveness Scale-11 (BIS-11) and the AX-expectancy version of the Continuous Performance Task (AX-CPT). This task engenders a conflict between two response tendencies by manipulating the frequency of specific trial types. We conducted mixed model analyses to determine the unique variance in behavioral and electrophysiological indices of relevant cognitive functions accounted for by the facets of BIS-11. Motor Impulsiveness was associated with smaller P3 across sites and conditions suggesting a general cognitive limitation not specific to the condition requiring the most inhibition, and larger N2 in some conditions indicating heightened conflict detection. Non-Planning Impulsiveness was related to smaller N2 when inhibiting a primed response and with greater P3 in some contexts. Attentional Impulsiveness appeared to be associated with an inefficient conflict detection system indicated by relatively normal engagement in trials involving the non-potent response, but relatively over engagement in the prepotent condition. Our findings suggest that sub-traits of impulsivity are differentially related to executive processes. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Impulsive differential inclusions a fixed point approach

    CERN Document Server

    Ouahab, Abdelghani; Henderson, Johnny

    2013-01-01

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

  18. Impulsive synchronization of Chen's hyperchaotic system

    International Nuclear Information System (INIS)

    Haeri, Mohammad; Dehghani, Mahsa

    2006-01-01

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

  19. [The acquisition in dogs of temporal regulation by differentiated reinforcement of the response duration using an exteroceptive component and the pharmacological modulation of this reflex (diazepam, clozapine)].

    Science.gov (United States)

    Bruviller, J; Chleid, E; Guer, H; Mersier, M

    1992-01-01

    Transformation of expectation phenomenon into the phenomenon of temporal regulation is usually achieved by the suppression of preliminary factors or by means of their physical modification. Our studies show that such transformation can be obtained in dogs using Kupalov paradigm with the presentation of additional stimuli. These stimuli strictly identical, from the physical point of view, to the signals which interrupt expectation are randomly introduced into the temporal limit. Absence of the reinforcement in response to the additional stimulus impels the animal to include temporal regulation in its behaviour, and an additional negative discriminative stimulus promotes an expression of active character of inhibition. These circumstances make our pattern closer to DRRD (differential reinforcement of response duration). In order to evaluate the merits of this procedure the influence was studied of anxiolytic (diazepam) and neuroleptic (closepine) on the stabilized reaction of experimental animals. The increase of responses duration by closepine and their shortening by diazepam as well as the influence of these pharmacological substances on the frequency of responses in dependence of dose, confirm the results of the previous studies of DRRD and DRL (differential reinforcement of low rate of responses) and prove differential sensitivity of our procedure to pharmacological substances.

  20. Mu and delta opioid receptors oppositely regulate motor impulsivity in the signaled nose poke task.

    Directory of Open Access Journals (Sweden)

    Mary C Olmstead

    Full Text Available Impulsivity is a primary feature of many psychiatric disorders, most notably attention deficit hyperactivity disorder and drug addiction. Impulsivity includes a number of processes such as the inability to delay gratification, the inability to withhold a motor response, or acting before all of the relevant information is available. These processes are mediated by neural systems that include dopamine, serotonin, norepinephrine, glutamate and cannabinoids. We examine, for the first time, the role of opioid systems in impulsivity by testing whether inactivation of the mu- (Oprm1 or delta- (Oprd1 opioid receptor gene alters motor impulsivity in mice. Wild-type and knockout mice were examined on either a pure C57BL6/J (BL6 or a hybrid 50% C57Bl/6J-50% 129Sv/pas (HYB background. Mice were trained to respond for sucrose in a signaled nose poke task that provides independent measures of associative learning (responses to the reward-paired cue and motor impulsivity (premature responses. Oprm1 knockout mice displayed a remarkable decrease in motor impulsivity. This was observed on the two genetic backgrounds and did not result from impaired associative learning, as responses to the cue signaling reward did not differ across genotypes. Furthermore, mutant mice were insensitive to the effects of ethanol, which increased disinhibition and decreased conditioned responding in wild-type mice. In sharp contrast, mice lacking the Oprd1 gene were more impulsive than controls. Again, mutant animals showed no deficit in associative learning. Ethanol completely disrupted performance in these animals. Together, our results suggest that mu-opioid receptors enhance, whereas delta-opioid receptors inhibit, motor impulsivity. This reveals an unanticipated contribution of endogenous opioid receptor activity to disinhibition. In a broader context, these data suggest that alterations in mu- or delta-opioid receptor function may contribute to impulse control disorders.

  1. Impulse control disorders in adult psychiatric inpatients.

    Science.gov (United States)

    Grant, Jon E; Levine, Laura; Kim, Daniel; Potenza, Marc N

    2005-11-01

    The authors' goal was to examine the prevalence of impulse control disorders in psychiatric inpatients. They used the Minnesota Impulsive Disorders Interview, a semistructured clinical interview assessing pathological gambling, trichotillomania, kleptomania, pyromania, intermittent explosive disorder, compulsive buying, and compulsive sexual behavior, to screen 204 consecutively admitted psychiatric inpatients. One hundred twelve of the inpatients were women (54.9%), and the mean age of the 204 inpatients was 40.5 years (SD=13.2, range=18-83). Patients whose screen was positive for an impulse control disorder were evaluated with structured clinical interviews. Sixty-three patients (30.9%) were diagnosed with at least one current impulse control disorder. The most common impulse control disorders were compulsive buying (N=19 [9.3%]), kleptomania (N=16 [7.8%]), and pathological gambling (N=14 [6.9%]). Patients with and without co-occurring impulse control disorders did not differ significantly from each other on demographic measures or number or type of psychiatric diagnoses other than impulse control disorders. Impulse control disorders appear common among psychiatric inpatients. Additional, larger studies are needed to examine the prevalence of impulse control disorders in the general population and specific psychiatric groups.

  2. Dissipative control for singular impulsive dynamical systems

    Directory of Open Access Journals (Sweden)

    Li Yang

    2012-04-01

    Full Text Available The aim of this work is to study the dissipative control problem for singular impulsive dynamical systems. We start by introducing the impulse to the singular systems, and give the definition of the dissipation for singular impulsive dynamical systems. Then we discuss the dissipation of singular impulsive dynamical systems, we obtain some sufficient and necessary conditions for dissipation of these systems by solving some linear matrix inequalities (LMIs. By using this method, we design a state feedback controller to make the closed-loop system dissipative. At last, we testify the feasibility of the method by a numerical example.

  3. High-Resolution Analysis of Seismic Air Gun Impulses and Their Reverberant Field as Contributors to an Acoustic Environment.

    Science.gov (United States)

    Guerra, Melania; Dugan, Peter J; Ponirakis, Dimitri W; Popescu, Marian; Shiu, Yu; Rice, Aaron N; Clark, Christopher W

    2016-01-01

    In September and October 2011, a seismic survey took place in Baffin Bay, Western Greenland, in close proximity to a marine protected area (MPA). As part of the mitigation effort, five bottom-mounted marine acoustic recording units (MARUs) collected data that were used for the purpose of measuring temporal and spectral features from each impulsive event, providing a high-resolution record of seismic reverberation persistent after the direct impulse. Results were compared with ambient-noise levels as computed after the seismic survey to evidence that as a consequence of a series of repeating seismic impulses, sustained elevated levels create the potential for masking.

  4. Spatio-temporal dynamics in global rice gene expression (Oryza sativa L.) in response to high ammonium stress.

    Science.gov (United States)

    Sun, Li; Di, Dongwei; Li, Guangjie; Kronzucker, Herbert J; Shi, Weiming

    2017-05-01

    Ammonium (NH 4 + ) is the predominant nitrogen (N) source in many natural and agricultural ecosystems, including flooded rice fields. While rice is known as an NH 4 + -tolerant species, it nevertheless suffers NH 4 + toxicity at elevated soil concentrations. NH 4 + excess rapidly leads to the disturbance of various physiological processes that ultimately inhibit shoot and root growth. However, the global transcriptomic response to NH 4 + stress in rice has not been examined. In this study, we mapped the spatio-temporal specificity of gene expression profiles in rice under excess NH 4 + and the changes in gene expression in root and shoot at various time points by RNA-Seq (Quantification) using Illumina HiSeqTM 2000. By comparative analysis, 307 and 675 genes were found to be up-regulated after 4h and 12h of NH 4 + exposure in the root, respectively. In the shoot, 167 genes were up-regulated at 4h, compared with 320 at 12h. According to KEGG analysis, up-regulated DEGs mainly participate in phenylpropanoid (such as flavonoid) and amino acid (such as proline, cysteine, and methionine) metabolism, which is believed to improve NH 4 + stress tolerance through adjustment of energy metabolism in the shoot, while defense and signaling pathways, guiding whole-plant acclimation, play the leading role in the root. We furthermore critically assessed the roles of key phytohormones, and found abscisic acid (ABA) and ethylene (ET) to be the major regulatory molecules responding to excess NH 4 + and activating the MAPK (mitogen-activated protein kinase) signal-transduction pathway. Moreover, we found up-regulated hormone-associated genes are involved in regulating flavonoid biosynthesis and are regulated by tissue flavonoid accumulation. Copyright © 2017 Elsevier GmbH. All rights reserved.

  5. Enhancer regions responsible for temporal and cell-type-specific expression of a spore coat gene in Dictyostelium.

    Science.gov (United States)

    Fosnaugh, K L; Loomis, W F

    1993-05-01

    The extracellular spore coat of Dictyostelium discoideum is composed of three major proteins, SP96, SP70, and SP60, encoded by the cotA, cotB, and cotC genes, respectively. The spore coat proteins are coordinately synthesized in prespore cells shortly after aggregation, stored in prespore vesicles during the slug stage, and secreted during encapsulation of spores. We have ligated various portions of the upstream region of cotB to lacZ such that a protein consisting of the first nine amino acids of SP70 fused to beta-galactosidase is synthesized in prespore cells. Individual cells that accumulate the enzyme can be observed in situ during early aggregation due to the sensitivity of the assay. We have found that prespore cells first appear in a random distribution throughout the aggregates with no indication of spatial localization. They subsequently sort out from prestalk cells that form a tip on the aggregates. The cotB regulatory region was subdivided into a proximal and a distal region, each of which could independently direct proper temporal and cell-type control. Transcriptional activity directed by these two regions appears to be additive in the full-length regulatory region. The proximal region was shown to be complex in that removal of certain portions partially reduced transcriptional activity while removal of other portions abolished all activity. Nevertheless, cells transformed with constructs showing attenuated activity expressed the fusion gene at the proper time in development and the activity was localized to prespore cells. The cis-acting regions responsible for all aspects of cotB regulation appear to be closely opposed within the minimal essential sequence of the proximal region.

  6. Structural Changes of Desertified and Managed Shrubland Landscapes in Response to Drought: Spectral, Spatial and Temporal Analyses

    Directory of Open Access Journals (Sweden)

    Tarin Paz-Kagan

    2014-08-01

    Full Text Available Drought events cause changes in ecosystem function and structure by reducing the shrub abundance and expanding the biological soil crusts (biocrusts. This change increases the leakage of nutrient resources and water into the river streams in semi-arid areas. A common management solution for decreasing this loss of resources is to create a runoff-harvesting system (RHS. The objective of the current research is to apply geo-information techniques, including remote sensing and geographic information systems (GIS, on the watershed scale, to monitor and analyze the spatial and temporal changes in response to drought of two source-sink systems, the natural shrubland and the human-made RHSs in the semi-arid area of the northern Negev Desert, Israel. This was done by evaluating the changes in soil, vegetation and landscape cover. The spatial changes were evaluated by three spectral indices: Normalized Difference Vegetation Index (NDVI, Crust Index (CI and landscape classification change between 2003 and 2010. In addition, we examined the effects of environmental factors on NDVI, CI and their clustering after successive drought years. The results show that vegetation cover indicates a negative ∆NDVI change due to a reduction in the abundance of woody vegetation. On the other hand, the soil cover change data indicate a positive ∆CI change due to the expansion of the biocrusts. These two trends are evidence for degradation processes in terms of resource conservation and bio-production. A considerable part of the changed area (39% represents transitions between redistribution processes of resources, such as water, sediments, nutrients and seeds, on the watershed scale. In the pre-drought period, resource redistribution mainly occurred on the slope scale, while in the post-drought period, resource redistribution occurred on the whole watershed scale. However, the RHS management is effective in reducing leakage, since these systems are located on the

  7. Spatial-Temporal Characteristics and Climatic Responses of Water Level Fluctuations of Global Major Lakes from 2002 to 2010

    Directory of Open Access Journals (Sweden)

    Chao Tan

    2017-02-01

    Full Text Available As one of the most important geographical units affected by global climate change, lakes are sensitive to climatic changes and are considered “indicators” of climate and the environment. In this study, changes in the spatial-temporal characteristics of the water levels of 204 global major lakes are systematically analyzed using satellite altimetry data (Hydroweb product from 2002 to 2010. Additionally, the responses of the major global lake levels to climatic fluctuations are analyzed using Global Land Surface Assimilation System (GLDAS data (temperature and precipitation. The results show that the change rates of most global lakes exceed 0, which means that the lake levels of these lakes are rising. The change rates of the lake levels are between −0.3~0.3 m/a, which indicates that the rate of change in the water-level of most lakes is not obvious. A few lakes have a particularly sharp change rate, between −5.84~−2 m/a or 0.7~1.87 m/a. Lakes with increasing levels are mainly located in the mountain and plateau regions, and the change rates in the coastal highlands are more evident. The global temperatures rise by a change rate of 0.0058 °C/a, while the global precipitation decreases by a change rate of −0.6697 mm/a. However, there are significant regional differences in both temperature and precipitation. In addition, the impact of precipitation on the water level of lakes is significant and straightforward, while the impact of temperature is more complex. A study of lake levels on a global scale would be quite useful for a better understanding of the impact which climate change has on surface water resources.

  8. Towards a General Model of Temporal Discounting

    Science.gov (United States)

    van den Bos, Wouter; McClure, Samuel M.

    2013-01-01

    Psychological models of temporal discounting have now successfully displaced classical economic theory due to the simple fact that many common behavior patterns, such as impulsivity, were unexplainable with classic models. However, the now dominant hyperbolic model of discounting is itself becoming increasingly strained. Numerous factors have…

  9. Time-domain multiplexed high resolution fiber optics strain sensor system based on temporal response of fiber Fabry-Perot interferometers.

    Science.gov (United States)

    Chen, Jiageng; Liu, Qingwen; He, Zuyuan

    2017-09-04

    We developed a multiplexed strain sensor system with high resolution using fiber Fabry-Perot interferometers (FFPI) as sensing elements. The temporal responses of the FFPIs excited by rectangular laser pulses are used to obtain the strain applied on each FFPI. The FFPIs are connected by cascaded couplers and delay fiber rolls for the time-domain multiplexing. A compact optoelectronic system performing closed-loop cyclic interrogation is employed to improve the sensing resolution and the frequency response. In the demonstration experiment, 3-channel strain sensing with resolutions better than 0.1 nε and frequency response higher than 100 Hz is realized.

  10. Effects of mood state on impulsivity in pathological buying.

    Science.gov (United States)

    Nicolai, Jennifer; Darancó, Stefaniá; Moshagen, Morten

    2016-10-30

    Pathological buying is characterized by irrepressible buying behaviour and its negative consequences. A possible mechanism contributing to its development and maintenance is that buying episodes act as a maladaptive strategy to cope with negative emotions. Accordingly, pathological buying has been repeatedly associated with impulsivity, in particular with the tendency to experience strong reactions under negative affect. Relying on an experimental mood induction procedure, the present study tested in a sample of 100 individuals (a) whether individuals with pathological buying symptoms respond more impulsively in the Go/No-Go Task (as a measure of the behavioural inhibition aspect of impulsivity) and (b) whether this association is more pronounced in a negative mood. While controlling for comorbidities, the results show that pathological buying is associated with faster responses and a larger number of commission errors. Moreover, a significant interaction indicated that the association between pathological buying and performance the Go/No-Go Task was stronger in the negative mood condition. The present study thus shows that pathological buying is associated with deficits in the behavioural inhibition component of impulsivity. These deficits are most pronounced when mood is negative; in turn, this provides an explanation for the occurrence of excessive buying episodes following negative affect. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  11. Alcohol use and drunk driving: the modifying effect of impulsivity.

    Science.gov (United States)

    Moan, Inger Synnøve; Norström, Thor; Storvoll, Elisabet E

    2013-01-01

    The aim of this study was twofold: (a) to examine how an increase in the frequency of heavy drinking episodes affects the incidence of drunk driving and (b) to examine whether the effect of alcohol use on drunk driving is contingent on impulsivity. Two waves of the Young in Norway Longitudinal Study were applied (N = 2,603; response rate: 67%), when the respondents were on average 17 (1994) and 28 (2005) years of age. Measurements consisted of self-reported heavy episodic drinking, drunk driving, and impulsivity. The first difference method was applied to estimate the association between heavy episodic drinking and drunk driving. This means that changes in the frequency of drunk driving were regressed on changes in the frequency of drinking. In this way, the effects of time-invariant confounders were eliminated. The results showed that every additional episode of heavy drinking was associated with a 2.6% increase in the frequency of drunk driving. The increase for males was significantly higher than among females. The analyses supported the hypothesis that impulsivity modifies the association between alcohol use and drunk driving. The association between drinking and drunk driving is significantly stronger among those with a high score on impulsivity compared with those who have a low score.

  12. Impulsive choice and impulsive action predict vulnerability to distinct stages of nicotine seeking in rats

    NARCIS (Netherlands)

    Diergaarde, L.; Pattij, T.; Poortvliet, I.; Hogenboom, F.; de Vries, W.; Schoffelmeer, A.N.M.; de Vries, T.J.

    2008-01-01

    Background: Although heavy smoking has been associated with impulsivity in humans, it is not clear whether poor impulse control represents a risk factor in the etiology of nicotine dependence. Methods: To address this issue, rats were selected on the basis of individual differences in impulsivity in

  13. Instantaneous and cumulative influences of competition on impulsive choices in domestic chicks.

    Directory of Open Access Journals (Sweden)

    Hidetoshi eAmita

    2011-09-01

    Full Text Available This study examined instantaneous and cumulative effects of competitive interactions on impulsiveness in the inter-temporal choices in domestic chicks. Chicks were trained to peck colored beads to gain delayed food rewards (1 or 6 grains of millet delivered after a delay ranging between 0–4.5 s, and were tested in binary choices between a small-short delay option (SS and a large-long delay alternative (LL. To examine whether competitive foraging instantaneously changes impulsiveness, we intraindividually compared choices between two consecutive tests in different contexts, one with competitors and another without. We found that (1 the number of the choice of LL was not influenced by competition in the tests, but (2 the operant peck latency was shortened by competition, suggesting a socially enhanced incentive for food. To further examine the lasting changes, two groups of chicks were consecutively trained and tested daily for 2 weeks according to a behavioral titration procedure, one with competitors and another without. Inter-group comparisons of the choices revealed that (3 choice impulsiveness gradually decreased along development, while (4 the chicks trained in competition maintained a higher level of impulsiveness. These results suggest that competitive foraging causes impulsive choices not by direct/contextual modification. Causal link between the instantaneous enhancement of incentive and the gradual effects on impulsivity remains to be examined. Some (yet unspecified factors may be indirectly involved.

  14. Diminished caudate and superior temporal gyrus responses to effort-based decision making in patients with first-episode major depressive disorder.

    Science.gov (United States)

    Yang, Xin-hua; Huang, Jia; Lan, Yong; Zhu, Cui-ying; Liu, Xiao-qun; Wang, Ye-fei; Cheung, Eric F C; Xie, Guang-rong; Chan, Raymond C K

    2016-01-04

    Anhedonia, the loss of interest or pleasure in reward processing, is a hallmark feature of major depressive disorder (MDD), but its underlying neurobiological mechanism is largely unknown. The present study aimed to examine the underlying neural mechanism of reward-related decision-making in patients with MDD. We examined behavioral and neural responses to rewards in patients with first-episode MDD (N=25) and healthy controls (N=25) using the Effort-Expenditure for Rewards Task (EEfRT). The task involved choices about possible rewards of varying magnitude and probability. We tested the hypothesis that individuals with MDD would exhibit a reduced neural response in reward-related brain structures involved in cost-benefit decision-making. Compared with healthy controls, patients with MDD showed significantly weaker responses in the left caudate nucleus when contrasting the 'high reward'-'low reward' condition, and blunted responses in the left superior temporal gyrus and the right caudate nucleus when contrasting high and low probabilities. In addition, hard tasks chosen during high probability trials were negatively correlated with superior temporal gyrus activity in MDD patients, while the same choices were negatively correlated with caudate nucleus activity in healthy controls. These results indicate that reduced caudate nucleus and superior temporal gyrus activation may underpin abnormal cost-benefit decision-making in MDD. Copyright © 2015 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2014-01-01

    Current cocaine treatments may be enhanced with a better understanding of the underlying mechanisms that contribute to the onset and maintenance of the disease, such as life stress and impulsivity. Life stress and impulsivity have previously been studied independently as contributors to drug use, and the current study expands upon past research by examining how these factors interact with one another. The aim of the current study was to evaluate the role of life stress in predicting impulsivity in a non-treatment seeking cocaine-dependent sample (N = 112). Analyses revealed that trait impulsivity (as measured by the Barratt Impulsiveness Scale) was associated with education (r = −3.09, p the age of 30 demonstrated lower impulsivity in decision-making (as measured by delay discounting) than those under 30 (t = 2.21, p = 0.03). Overall exposure to life stress was not significantly correlated to either aspect of impulsivity. However several specific life stressors were significantly related to greater impulsivity including having been put up for adoption or in foster care (t = −2.96, p < 0.01), and having a child taken away against their will (t = −2.68, p = 0.01). These findings suggest that age and education relate to impulsivity; and that while an overall compilation of life stress scores was not related to impulsivity, specific types of stress related to either being taken away from a parent or having a child taken away were. Future studies should assess these constructs longitudinally to restrict response bias. PMID:23796525

  18. Environmental contaminants and biomarker responses in fish from the Columbia River and its tributaries: spatial and temporal trends

    Science.gov (United States)

    Hinck, J.E.; Schmitt, C.J.; Blazer, V.S.; Denslow, N.D.; Bartish, T.M.; Anderson, P.J.; Coyle, J.J.; Dethloff, G.M.; Tillitt, D.E.

    2006-01-01

    . Other organochlorine pesticides did not exceed toxicity thresholds in fish or were detected infrequently. Total polychlorinated biphenyls (PCBs; > 0.11 ??g/g) and TCDD-EQs (> 5 pg/g) exceeded wildlife guidelines in fish from the middle and lower CRB, and ethoxyresorufin O-deethylase (EROD) activity was also elevated at many of the same sites. Temporal trend analysis indicated decreasing or stable concentrations of Pb, Se, Hg, p,p???-DDE, and PCBs at most sites where historical data were available. Altered biomarkers were noted in fish throughout the CRB. Fish from some stations had responded to chronic contaminant exposure as indicated by fish health and reproductive biomarker results. Although most fish from some sites had grossly visible external or internal lesions, histopathological analysis determined these to be inflammatory responses associated with helminth or myxosporidian parasites. Many largescale sucker from the Columbia River at Northport and Grand Coulee, WA had external lesions and enlarged spleens, which were likely associated with infections. Intersex male smallmouth bass (Micropterus dolomieu) were found in the Snake River at Lewiston, ID and the Columbia River at Warrendale, OR. Male bass, carp, and largescale sucker containing low concentrations of vitellogenin were common in the CRB, and comparatively high concentrations (> 0.3 mg/mL) were measured in male fish from the Flathead River at Creston, Montana, the Snake River at Ice Harbor Dam, WA, and the Columbia River at Vernita Bridge, WA and Warrendale, OR. Results from our study and other investigations indicate that continued monitoring in the CRB is warranted to identify consistently degraded sites and those with emerging problems. ?? 2005 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    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

  20. Impulsive smoking in a patient with Parkinson's disease treated with dopamine agonists.

    Science.gov (United States)

    Bienfait, Karina L; Menza, Matthew; Mark, Margery H; Dobkin, Roseanne D

    2010-04-01

    Impulse control disorders, including pathological gambling, binge eating, compulsive shopping and hypersexual behaviors, have frequently been reported as a side effect of dopaminergic medications for Parkinson's disease (PD). Here we describe a patient with PD who developed an unusual manifestation of impulsive behaviors, including cigarette smoking, associated with an increase in dopamine agonist medication. We postulate this to be related to an overstimulation of mesolimbic dopamine receptors responsible for reward-seeking behaviors. Further research is needed to examine impulsive cigarette smoking in PD. (c) 2009 Elsevier Ltd. All rights reserved.

  1. The effects of acute tryptophan depletion on impulsivity and mood in adolescents engaging in non-suicidal self-injury.

    Science.gov (United States)

    Fikke, Linn T; Melinder, Annika; Landrø, Nils I

    2013-01-01

    Non-suicidal self-injury (NSSI) is associated with impaired emotion regulation and impulsivity. Low serotonin (5-hydroxytryptamine) function is associated with NSSI, impaired emotion regulation and impulsivity. We investigated the effects of experimentally lowered 5-hydroxytryptamine activity, via acute tryptophan depletion (ATD), on impulsive action, reflection impulsivity and mood in female adolescents engaging in NSSI. Thirty-two female adolescents engaging in NSSI participated in a parallel group ATD study. Following ATD, impulsive action was assessed using the Continuous Performance Test, Identical Pairs Version. Reflection impulsivity was assessed using the Matching Familiar Figures Test. Mood-lowering was examined using the Profile of Mood States. Following ATD, the participants showed an impulsive response style (as reflected in their low β) and increased attentional capacity (as reflected in their elevated d'). ATD did not affect reflection impulsivity or mood. Acute tryptophan depletion caused an impulsive response style and increased attentional capacity. Importantly, the findings suggest that low serotonin function is a vulnerability among female adolescents for engaging in NSSI when in emotional distress. Copyright © 2013 John Wiley & Sons, Ltd.

  2. On Some New Impulsive Integral Inequalities

    OpenAIRE

    Jianli Li

    2008-01-01

    We establish some new impulsive integral inequalities related to certain integral inequalities arising in the theory of differential equalities. The inequalities obtained here can be used as handy tools in the theory of some classes of impulsive differential and integral equations.

  3. Robust dissipativity for uncertain impulsive dynamical systems

    Directory of Open Access Journals (Sweden)

    Liu Bin

    2003-01-01

    Full Text Available We discuss the robust dissipativity with respect to the quadratic supply rate for uncertain impulsive dynamical systems. By employing the Hamilton-Jacobi inequality approach, some sufficient conditions of robust dissipativity for this kind of system are established. Finally, we specialize the obtained results to the case of uncertain linear impulsive dynamical systems.

  4. Impulsive Vaccination for an Epidemiology Model

    Science.gov (United States)

    De la Sen, M.; Garrido, A. J.

    2017-03-01

    This paper investigates sufficient conditions of almost periodic sand periodic solutions of an integral model under impulsive controls. Since the model is of generic epidemiological interest, such impulsive controls are either vaccination actions or abrupt variations of the infected population due to infected immigration or lost of infective numbers due to either vaccination or lost of infected population by out-migration.

  5. Non-instantaneous impulses in differential equations

    CERN Document Server

    Agarwal, Ravi; O'Regan, Donal

    2017-01-01

    This monograph is the first published book devoted to the theory of differential equations with non-instantaneous impulses. It aims to equip the reader with mathematical models and theory behind real life processes in physics, biology, population dynamics, ecology and pharmacokinetics. The authors examine a wide scope of differential equations with non-instantaneous impulses through three comprehensive chapters, providing an all-rounded and unique presentation on the topic, including: - Ordinary differential equations with non-instantaneous impulses (scalar and n-dimensional case) - Fractional differential equa tions with non-instantaneous impulses (with Caputo fractional derivatives of order q ϵ (0, 1)) - Ordinary differential equations with non-instantaneous impulses occurring at random moments (with exponential, Erlang, or Gamma distribution) Each chapter focuses on theory, proofs and examples, and contains numerous graphs to enrich the reader’s understanding. Additionally, a carefully selected bibliogr...

  6. Temporal framing and consideration of future consequences: effects on smokers' and at-risk nonsmokers' responses to cigarette health warnings.

    Science.gov (United States)

    Zhao, Xiaoquan; Nan, Xiaoli; Iles, Irina Alexandra; Yang, Bo

    2015-01-01

    This research examines the influence of temporal framing (long-term vs. short-term) and individual difference in consideration of future consequences (CFC) on the effectiveness of cigarette health warnings among smokers and at-risk nonsmokers in a college population. An online experiment (N = 395) revealed a three-way interaction among temporal framing, CFC, and smoking status. The results among at-risk nonsmokers supported the temporal fit hypothesis--those high in CFC responded more favorably to long-term framing, whereas those low in CFC responded more positively to short-term framing. The findings among smokers revealed a different pattern in which short-term framing was more effective among high-CFC smokers, whereas among low-CFC smokers the framing effect was not distinct. Theoretical and practical implications of the findings are discussed.

  7. Variable delay-to-signal: a fast paradigm for assessment of aspects of impulsivity in rats

    Directory of Open Access Journals (Sweden)

    Hugo eLeite-Almeida

    2013-10-01

    Full Text Available Testing impulsive behavior in rodents is challenging and labor-intensive. We developed a new behavioral paradigm – the Variable Delay-to-Signal (VDS test – that provides rapid and simultaneous assessment of response and decision impulsivity in rodents. Presentation of a light at variable delays signals the permission for action (nose poke contingent with a reward. Two blocks of 25 trials at 3s delay flank a block of 70 trials in which light is presented with randomly selected 6s or 12s delays. Exposure to such large delays boosts the rate of premature responses when the delay drops to 3s in the final block, an effect that is blunted by an acute methamphetamine challenge and that correlates with the delay-discounting paradigm (choice impulsivity. Finally, as expected, treatment with the NMDA antagonist MK-801 caused a generalized response increase in all VDS blocks. The pharmacological validation, particularly with methamphetamine which has a well established dual effect on response and decision impulsivity, and the correlations between the impulsive behavior in the delay-discounting and VDS paradigms, suggests that the later is able to provide, in a single session, a multi-dimensional assessment of impulsive behavior.

  8. Tourette-like behaviors in the normal population are associated with hyperactive/impulsive ADHD-like behaviors but do not relate to deficits in conditioned inhibition or response inhibition

    Directory of Open Access Journals (Sweden)

    Nadja eHeym

    2014-09-01

    Full Text Available Attention-Deficit Hyperactivity Disorder (ADHD and Tourette Syndrome (TS present as distinct conditions clinically; however, comorbidity and inhibitory control deficits have been proposed for both. Whilst such deficits have been studied widely within clinical populations, findings are mixed – partly due to comorbidity and/or medication effects - and studies have rarely distinguished between subtypes of the disorders. Studies in the general population are sparse. Using a continuity approach, the present study examined (i the relationships between inattentive and hyperactive/impulsive aspects of ADHD and TS-like behaviors in the general population, and (ii their unique associations with automatic and executive inhibitory control, as well as (iii yawning (a proposed behavioral model of TS. One hundred and thirty-eight participants completed self-report measures for ADHD and TS-like behaviors as well as yawning, and a conditioned inhibition task to assess automatic inhibition. A sub-sample of fifty-four participants completed three executive inhibition tasks. An exploratory factor analysis of the TS behavior checklist supported a distinction between phonic and motor like pure TS behaviors. Whilst hyperactive/impulsive aspects of ADHD were associated with increased pure and compulsive TS-like behaviors, inattention in isolation was related to reduced obsessive-compulsive TS-like behaviors. TS-like behaviors were associated with yawning during situations of inactivity, and specifically motor TS was related to yawning during stress. Phonic TS and inattention aspects of ADHD were associated with yawning during concentration/activity. Whilst executive interference control deficits were linked to hyperactive/impulsive ADHD-like behaviors, this was not the case for inattentive ADHD or TS-like behaviors, which instead related to increased performance on some measures. No associations were observed for automatic conditioned inhibition.

  9. Differential associations between impulsivity and risk-taking and brain activations underlying working memory in adolescents

    Science.gov (United States)

    Panwar, Karni; Rutherford, Helena J.V.; Mencl, W. Einar; Lacadie, Cheryl M.; Potenza, Marc N.; Mayes, Linda C.

    2014-01-01

    Increased impulsivity and risk-taking are common during adolescence and relate importantly to addictive behaviors. However, the extent to which impulsivity and risk-taking relate to brain activations that mediate cognitive processing is not well understood. Here we examined the relationships between impulsivity and risk-taking and the neural correlates of working memory. Neural activity was measured in 18 adolescents (13–18 years) while they engaged in a working memory task that included verbal and visuospatial components that each involved encoding, rehearsal and recognition stages. Risk-taking and impulsivity were assessed using the Balloon Analogue Risk Task (BART) and the adolescent version of the Barratt Impulsiveness Scale -11 (BIS-11A), respectively. We found overlapping as well as distinct regions subserving the different stages of verbal and visuospatial working memory. In terms of risk-taking, we found a positive correlation between BART scores and activity in subcortical regions (e.g., thalamus, dorsal striatum) recruited during verbal rehearsal, and an inverse correlation between BART scores and cortical regions (e.g., parietal and temporal regions) recruited during visuospatial rehearsal. The BIS-11A evidenced that motor impulsivity was associated with activity in regions recruited during all stages of working memory, while attention and non-planning impulsivity was only associated with activity in regions recruited during recognition. In considering working memory, impulsivity and risk-taking together, both impulsivity and risk-taking were associated with activity in regions recruited during rehearsal; however, during verbal rehearsal, differential correlations were found. Specifically, positive correlations were found between: (1) risk-taking and activity in subcortical regions, including the thalamus and dorsal striatum; and, (2) motor impulsivity and activity in the left inferior frontal gyrus, insula, dorsolateral and ventrolateral prefrontal

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

    Science.gov (United States)

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

    2014-02-01

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

  11. Differences in Inhibitory Control between Impulsive and Premeditated Aggression in Juvenile Inmates

    Directory of Open Access Journals (Sweden)

    Zhuo Zhang

    2017-07-01

    Full Text Available Inhibitory control dysfunction was considered a universal characteristic of violent offenders. The aim of this study was to examine differences in inhibitory control between two subtypes of violent youth; those displaying predominantly impulsive and those presenting predominantly premeditated aggression (PM. Forty-four juvenile offenders, defined on the basis of the Procedures for the Classification of Aggressive/Violent Acts (Stanford and Barratt, 2001 participated (N = 23: impulsive; N = 21 premeditated. A visual Go/NoGo task was used to compare behavioral responses and event-related potentials (ERPs between groups. The task contained two letters (W and M, W was the Go stimulus and M the NoGo stimulus. The impulsive youth showed a significantly greater decrease in N2 latency for Go relative to NoGo trials than the premeditated aggressive youth. The differentiation in N2 amplitude between Go and NoGo (N2d was negatively correlated with impulsivity of aggression. Both groups showed no significant central NoGo P3. Our findings suggest that impulsive violent youth show stronger prepotent responses and impaired conflict monitoring during early inhibitory control processing relative to premeditated aggressive youth. Both impulsive and premeditated violent youth may show impaired response inhibition at the late processing stage of inhibitory control.

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

    Science.gov (United States)

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

    2016-12-01

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

  13. Impulsivity predicts time to reach euthymia in adults with bipolar disorder.

    Science.gov (United States)

    Dawson, Erica L; Shear, Paula K; Howe, Steven R; Adler, Caleb M; DelBello, Melissa P; Fleck, David E; Strakowski, Stephen M

    2014-12-01

    Specific demographic and illness characteristics have been identified as predictors of overall morbidity and treatment course among individuals with bipolar disorder. However, the role of specific cognitive limitations on disease severity and treatment response is unclear. The present study evaluated whether impulsiveness during acute mania was a significant predictor of achieving euthymia within one year following psychiatric hospitalization. Participants were 94 adult inpatients (60 manic) with bipolar I disorder. Baseline symptom severity was assessed using the Young Mania Rating Scale and the Montgomery-Åsberg Depression Rating Scale. Impulsivity was measured with the Stop Signal Task, Degraded Stimulus Continuous Performance Task, Delayed Response Task, and Barratt Impulsiveness Scale-11. Individual predictors of time to reach euthymia included fewer depressive symptoms and better impulse control at baseline, later age at illness onset, shorter illness duration, and the absence of comorbid attention-deficit hyperactivity disorder. Self-reported impulsivity was a significant independent predictor of time to euthymia, even after accounting for relevant clinical variables. Better trait impulse control may be associated with better treatment responsiveness among adults with bipolar disorder. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. Risk Factors and Impulsivity in Obesity

    Directory of Open Access Journals (Sweden)

    Bilge Burcak Annagur

    2010-12-01

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

  15. From impulses to maladaptive actions: the insula is a neurobiological gate for the development of compulsive behavior.

    Science.gov (United States)

    Belin-Rauscent, A; Daniel, M-L; Puaud, M; Jupp, B; Sawiak, S; Howett, D; McKenzie, C; Caprioli, D; Besson, M; Robbins, T W; Everitt, B J; Dalley, J W; Belin, D

    2016-04-01

    Impulsivity is an endophenotype of vulnerability for compulsive behaviors. However, the neural mechanisms whereby impulsivity facilitates the development of compulsive disorders, such as addiction or obsessive compulsive disorder, remain unknown. We first investigated, in rats, anatomical and functional correlates of impulsivity in the anterior insular (AI) cortex by measuring both the thickness of, and cellular plasticity markers in, the AI with magnetic resonance imaging and in situ hybridization of the immediate early gene zif268, respectively. We then investigated the influence of bilateral AI cortex lesions on the high impulsivity trait, as measured in the five-choice serial reaction time task (5-CSRTT), and the associated propensity to develop compulsivity as measured by high drinking levels in a schedule-induced polydipsia procedure (SIP). We demonstrate that the AI cortex causally contributes to individual vulnerability to impulsive-compulsive behavior in rats. Motor impulsivity, as measured by premature responses in the 5-CSRTT, was shown to correlate with the thinness of the anterior region of the insular cortex, in which highly impulsive (HI) rats expressed lower zif268 mRNA levels. Lesions of AI reduced impulsive behavior in HI rats, which were also highly susceptible to develop compulsive behavior as measured in a SIP procedure. AI lesions also attenuated both the development and the expression of SIP. This study thus identifies the AI as a novel neural substrate of maladaptive impulse control mechanisms that may facilitate the development of compulsive disorders.

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

    Science.gov (United States)

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

    2017-05-01

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

  17. Optimal impulsive manoeuvres and aerodynamic braking

    Science.gov (United States)

    Jezewski, D. J.

    1985-01-01

    A method developed for obtaining solutions to the aerodynamic braking problem, using impulses in the exoatmospheric phases is discussed. The solution combines primer vector theory and the results of a suboptimal atmospheric guidance program. For a specified initial and final orbit, the solution determines: (1) the minimum impulsive cost using a maximum of four impulses, (2) the optimal atmospheric entry and exit-state vectors subject to equality and inequality constraints, and (3) the optimal coast times. Numerical solutions which illustrate the characteristics of the solution are presented.

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

    Science.gov (United States)

    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.

  19. Impulsive phase of solar flares: theory

    International Nuclear Information System (INIS)

    Mackinnon, A.L.

    1986-01-01

    The paper reviews the theoretical interpretation of impulsive phase phenomena in solar flares. The impulsive phase is defined to be that period of approx. 10 - 100s duration, during which the flare radiative output undergoes its most rapid, dramatic increase and decrease. The interpretation of the various impulsive phase radiation signatures are examined, including the i) hard x-ray emission, ii) radio emission, iii) UV, Hα and white light emissions and iv) gamma-ray emission. The acceleration mechanisms are discussed with respect to candidate acceleration mechanisms, and the synthesis of the theory and observations. (UK)

  20. Active control of repetitive impulsive noise in a non-minimum phase system using an optimal iterative learning control algorithm

    Science.gov (United States)

    Zhou, Y. L.; Yin, Y. X.; Zhang, Q. Z.

    2013-09-01

    In this paper, active control of repetitive impulsive noise is studied. An optimal iterative learning control (ILC) algorithm is developed for an active noise control (ANC) system with a non-minimum phase secondary path. A non-causal transversal finite impulse response (FIR) filter is used as the ILC learning filter, and the impulse response coefficients of the FIR filter are designed according to the asymptotically stable and monotonically convergent criterion in time domain. Computer simulations have been carried out to suggest that the proposed algorithm is effective for attenuating repetitive impulsive noise, and then the proposed algorithm has been implemented in an experimental ANC system. Experimental results show that the proposed scheme has good performance for repetitive impulsive noise attenuation in a non-minimum phase ANC system.

  1. Computation of long-distance propagation of impulses elicited by Poisson-process stimulation.

    Science.gov (United States)

    Moradmand, K; Goldfinger, M D

    1995-12-01

    1. The purpose of this work was to determine whether computed temporally coded axonal information generated by Poisson process stimulation were modified during long-distance propagation, as originally suggested by S. A. George. Propagated impulses were computed with the use of the Hodgkin-Huxley equations and cable theory to simulate excitation and current spread in 100-microns-diam unmyelinated axons, whose total length was 8.1 cm (25 lambda) or 101.4 cm (312.5 lambda). Differential equations were solved numerically, with the use of trapezoidal integration over small, constant electrotonic and temporal steps (0.125 lambda and 1.0 microsecond, respectively). 2. Using dual-pulse stimulation, we confirmed that for interstimulus intervals between 5 and 11 ms, the conduction velocity of the second of a short-interval pair of impulses was slower than that of the first impulse. Further, with sufficiently long propagation distance, the second impulse's conduction velocity increased steadily and eventually approached that of the first impulse. This effect caused a spatially varying interspike interval: as propagation proceeded, the interspike interval increased and eventually approached stabilization. 3. With Poisson stimulation, the peak amplitude of propagating action potentials varied with interspike interval durations between 5 and 11 ms. Such amplitude attenuation was caused by the incomplete relaxation of parameters n (macroscopic K-conductance activation) and h (macroscopic Na-conductance inactivation) during the interspike period. 4. The stochastic properties of the impulse train became less Poisson-like with propagation distance. In cases of propagation over 99.4 cm, the impulse trains developed marked periodicities in Interevent Interval Distribution and Expectation Density function because of the axially modulated transformation of interspike intervals. 5. Despite these changes in impulse train parameters, the arithmetic value of the mean interspike interval did

  2. fMRI brain response during sentence reading comprehension in children with benign epilepsy with centro-temporal spikes.

    Science.gov (United States)

    Malfait, D; Tucholka, A; Mendizabal, S; Tremblay, J; Poulin, C; Oskoui, M; Srour, M; Carmant, L; Major, P; Lippé, S

    2015-11-01

    Children with benign epilepsy with centro-temporal spikes (BECTS) often have language problems. Abnormal epileptic activity is found in central and temporal brain regions, which are involved in reading and semantic and syntactic comprehension. Using functional magnetic resonance imaging (fMRI), we examined reading networks in BECTS children with a new sentence reading comprehension task involving semantic and syntactic processing. Fifteen children with BECTS (age=11y 1m ± 16 m; 12 boys) and 18 healthy controls (age=11 y 8m ± 20 m; 11 boys) performed an fMRI reading comprehension task in which they read a pair of syntactically complex sentences and decided whether the target sentence (the second sentence in the pair) was true or false with respect to the first sentence. All children also underwent an exhaustive neuropsychological assessment. We demonstrated weaknesses in several cognitive domains in BECTS children. During the sentence reading fMRI task, left inferior frontal regions and bilateral temporal areas were activated in BECTS children and healthy controls. However, additional brain regions such as the left hippocampus and precuneus were activated in BECTS children. Moreover, specific activation was found in the left caudate and putamen in BECTS children but not in healthy controls. Cognitive results and accuracy during the fMRI task were associated with specific brain activation patterns. BECTS children recruited a wider network to perform the fMRI sentence reading comprehension task, with specific activation in the left dorsal striatum. BECTS cognitive performance differently predicted functional activation in frontal and temporal regions compared to controls, suggesting differences in brain network organisation that contribute to reading comprehension. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

  3. Spatial and Temporal Responses of Soil Erosion to Climate Change Impacts in a Transnational Watershed in Southeast Asia

    OpenAIRE

    Pham Quy Giang; Le Thi Giang; Kosuke Toshiki

    2017-01-01

    It has been widely predicted that Southeast Asia is among the regions facing the most severe climate change impacts. Despite this forecast, little research has been published on the potential impacts of climate change on soil erosion in this region. This study focused on the impact of climate change on spatial and temporal patterns of soil erosion in the Laos–Vietnam transnational Upper Ca River Watershed. The Soil and Water Assessment Tool (SWAT) coupled with downscaled global climate models...

  4. Historical and contemporary geographic data reveal complex spatial and temporal responses of vegetation to climate and land stewardship

    Science.gov (United States)

    Villarreal, Miguel L.; Norman, Laura M.; Webb, Robert H.; Turner, Raymond M.

    2013-01-01

    Vegetation and land-cover changes are not always directional but follow complex trajectories over space and time, driven by changing anthropogenic and abiotic conditions. We present a multi-observational approach to land-change analysis that addresses the complex geographic and temporal variability of vegetation changes related to climate and land use. Using land-ownership data as a proxy for land-use practices, multitemporal land-cover maps, and repeat photography dating to the late 19th century, we examine changing spatial and temporal distributions of two vegetation types with high conservation value in the southwestern United States: grasslands and riparian vegetation. In contrast to many reported vegetation changes, notably shrub encroachment in desert grasslands, we found an overall increase in grassland area and decline of xeroriparian and riparian vegetation. These observed change patterns were neither temporally directional nor spatially uniform over the landscape. Historical data suggest that long-term vegetation changes coincide with broad climate fluctuations while fine-scale patterns are determined by land-management practices. In some cases, restoration and active management appear to weaken the effects of climate on vegetation; therefore, if land managers in this region act in accord with on-going directional changes, the current drought and associated ecological reorganization may provide an opportunity to achieve desired restoration endpoints.

  5. Nucleus accumbens core lesions induce sub-optimal choice and reduce sensitivity to magnitude and delay in impulsive choice tasks

    Science.gov (United States)

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

    2017-01-01

    The nucleus accumbens core (NAc) has long been recognized as an important contributor to the computation of reward value that is critical for impulsive choice behavior. Impulsive choice refers to choosing a smaller-sooner (SS) over a larger-later (LL) reward when the LL is more optimal in terms of the rate of reward delivery. Two experiments examined the role of the NAc in impulsive choice and its component processes of delay and magnitude processing. Experiment 1 delivered an impulsive choice task with manipulations of LL reward magnitude, followed by a reward magnitude discrimination task. Experiment 2 tested impulsive choice under manipulations of LL delay, followed by temporal bisection and progressive interval tasks. NAc lesions, in comparison to sham control lesions, produced suboptimal preferences that resulted in lower reward earning rates, and led to reduced sensitivity to magnitude and delay within the impulsive choice task. The secondary tasks revealed intact reward magnitude and delay discrimination abilities, but the lesion rats persisted in responding more as the progressive interval increased during the session. The results suggest that the NAc is most critical for demonstrating good sensitivity to magnitude and delay, and adjusting behavior accordingly. Ultimately, the NAc lesions induced suboptimal choice behavior rather than simply promoting impulsive choice, suggesting that an intact NAc is necessary for optimal decision making. PMID:29146281

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

    Science.gov (United States)

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

    2010-04-01

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

  7. Association between self-reported impulsiveness and gray matter volume in healthy adults. An exploratory MRI study.

    Science.gov (United States)

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

    2018-03-19

    This exploratory study investigated the association between self-reported impulsiveness and cortical gray matter volume (GMV) of the entire cortex in healthy adults. As a secondary objective and based on preliminary findings concerning the positive association between self-reported impulsiveness and the slant of the forehead degrees (SFD), we analyzed associations between SFD, GMV and impulsiveness. We obtained 48 structural magnetic resonances. The participants also completed BIS 11 and profile pictures were obtained. SFD was measured by a photographic support and a protractor. The GMV of the whole cortex was obtained for each participant through Freesurfer. Firstly, we found negative and positive correlations between fronto-temporal and occipital areas respectively and BIS. Second, we found negative correlations between SFD and GMV in right postcentral gyrus, right caudal middle frontal gyrus, right transverse temporal cortex and positive correlation in left entorhinal cortex. Third, we observed a positive correlation between SFD and BIS in all impulsiveness scores. In conclusion, variations in fronto-temporal and posterior cerebral areas are crucial for BIS in healthy adults. Furthermore, SFD was associated with BIS and correlated with GMV areas involved in self-reported impulsiveness. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Impulsivity and eating behaviour: an examination of subtypes of impulsive behaviour and overeating in healthy females

    OpenAIRE

    Leitch, Margaret

    2011-01-01

    A wealth of support has shown higher levels of state and trait impulsivity can be found among those individuals prone to developing problematic eating behaviors and obesity. Thus, upon commencing the investigations in this thesis, it was hypothesized that impulsivity is an individual difference implicated in overeating behaviour.\\ud \\ud Increasing information indicates that there are divisions within impulsivity subtypes. Prior to this thesis, studies in the field of eating behaviour had not ...

  9. Active noise cancellation algorithms for impulsive noise.

    Science.gov (United States)

    Li, Peng; Yu, Xun

    2013-04-01

    Impulsive noise is an important challenge for the practical implementation of active noise control (ANC) systems. The advantages and disadvantages of popular filtered- X least mean square (FXLMS) ANC algorithm and nonlinear filtered-X least mean M-estimate (FXLMM) algorithm are discussed in this paper. A new modified FXLMM algorithm is also proposed to achieve better performance in controlling impulsive noise. Computer simulations and experiments are carried out for all three algorithms and the results are presented and analyzed. The results show that the FXLMM and modified FXLMM algorithms are more robust in suppressing the adverse effect of sudden large amplitude impulses than FXLMS algorithm, and in particular, the proposed modified FXLMM algorithm can achieve better stability without sacrificing the performance of residual noise when encountering impulses.

  10. Stability analysis of impulsive parabolic complex networks

    International Nuclear Information System (INIS)

    Wang Jinliang; Wu Huaining

    2011-01-01

    Highlights: → Two impulsive parabolic complex network models are proposed. → The global exponential stability of impulsive parabolic complex networks are considered. → The robust global exponential stability of impulsive parabolic complex networks are considered. - Abstract: In the present paper, two kinds of impulsive parabolic complex networks (IPCNs) are considered. In the first one, all nodes have the same time-varying delay. In the second one, different nodes have different time-varying delays. Using the Lyapunov functional method combined with the inequality techniques, some global exponential stability criteria are derived for the IPCNs. Furthermore, several robust global exponential stability conditions are proposed to take uncertainties in the parameters of the IPCNs into account. Finally, numerical simulations are presented to illustrate the effectiveness of the results obtained here.

  11. Impulsive fractional differential inclusions with infinite delay

    Directory of Open Access Journals (Sweden)

    Khalida Aissani

    2013-11-01

    Full Text Available In this article, we apply Bohnenblust-Karlin's fixed point theorem to prove the existence of mild solutions for a class of impulsive fractional equations inclusions with infinite delay. An example is given to illustrate the theory.

  12. Detecting Impulses in Mechanical Signals by Wavelets

    Directory of Open Access Journals (Sweden)

    Yang W-X

    2004-01-01

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

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

    Science.gov (United States)

    Bluschke, A; Roessner, V; Beste, C

    2016-04-01

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

  14. Distinct Circuits Underlie the Effects of 5-HT1B Receptors on Aggression and Impulsivity.

    Science.gov (United States)

    Nautiyal, Katherine M; Tanaka, Kenji F; Barr, Mary M; Tritschler, Laurent; Le Dantec, Yannick; David, Denis J; Gardier, Alain M; Blanco, Carlos; Hen, René; Ahmari, Susanne E

    2015-05-06

    Impulsive and aggressive behaviors are both modulated by serotonergic signaling, specifically through the serotonin 1B receptor (5-HT1BR). 5-HT1BR knockout mice show increased aggression and impulsivity, and 5-HT1BR polymorphisms are associated with aggression and drug addiction in humans. To dissect the mechanisms by which the 5-HT1BR affects these phenotypes, we developed a mouse model to spatially and temporally regulate 5-HT1BR expression. Our results demonstrate that forebrain 5-HT1B heteroreceptors expressed during an early postnatal period contribute to the development of the neural systems underlying adult aggression. However, distinct heteroreceptors acting during adulthood are involved in mediating impulsivity. Correlating with the impulsivity, dopamine in the nucleus accumbens is elevated in the absence of 5-HT1BRs and normalized following adult rescue of the receptor. Overall, these data show that while adolescent expression of 5-HT1BRs influences aggressive behavior, a distinct set of 5-HT1B receptors modulates impulsive behavior during adulthood. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Forensic Psychiatric Aspects of Impulse Control Disorders

    Directory of Open Access Journals (Sweden)

    Huseyin Soysal

    2015-03-01

    Full Text Available Impulse control disorders is an important psychiatric disorder group which draws attention in recent years. Attention deficit hyperactivity disorder and other classical disorders like pyromania, kleptomania, intermittent explosive disorder and compulsive buying could be evasuated under this topic. The aim of this article is to review forensic psychiatric aspects of impulse control disorders and evaluate the disorders in terms of their legal status. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2015; 7(1: 16-29

  16. Impulsive nature in collisional driven reconnection

    Energy Technology Data Exchange (ETDEWEB)

    Kitabata, Hideyuki; Hayashi, Takaya; Sato, Tetsuya

    1995-11-01

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

  17. Impulsive nature in collisional driven reconnection

    International Nuclear Information System (INIS)

    Kitabata, Hideyuki; Hayashi, Takaya; Sato, Tetsuya.

    1995-11-01

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

  18. ADHD-hyperactive/impulsive subtype in adults

    OpenAIRE

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

    2010-01-01

    This is the first study to evaluate ADHD-hyperactive/impulsive subtype in a large clinical sample of adults with ADHD. The Quality of Life, Effectiveness, Safety and Tolerability (QuEST) study included 725 adults who received clinician diagnoses of any ADHD subtype. Cross-sectional baseline data from 691 patients diagnosed with the hyperactive/impulsive (HI), inattentive (IA) and combined subtypes were used to compare the groups on the clinician administered ADHD-RS, clinical features and hea...

  19. Transient vibration analytical modeling and suppressing for vibration absorber system under impulse excitation

    Science.gov (United States)

    Wang, Xi; Yang, Bintang; Yu, Hu; Gao, Yulong

    2017-04-01

    The impulse excitation of mechanism causes transient vibration. In order to achieve adaptive transient vibration control, a method which can exactly model the response need to be proposed. This paper presents an analytical model to obtain the response of the primary system attached with dynamic vibration absorber (DVA) under impulse excitation. The impulse excitation which can be divided into single-impulse excitation and multi-impulse excitation is simplified as sinusoidal wave to establish the analytical model. To decouple the differential governing equations, a transform matrix is applied to convert the response from the physical coordinate to model coordinate. Therefore, the analytical response in the physical coordinate can be obtained by inverse transformation. The numerical Runge-Kutta method and experimental tests have demonstrated the effectiveness of the analytical model proposed. The wavelet of the response indicates that the transient vibration consists of components with multiple frequencies, and it shows that the modeling results coincide with the experiments. The optimizing simulations based on genetic algorithm and experimental tests demonstrate that the transient vibration of the primary system can be decreased by changing the stiffness of the DVA. The results presented in this paper are the foundations for us to develop the adaptive transient vibration absorber in the future.

  20. Cue-induced striatal dopamine release in Parkinson's disease-associated impulsive-compulsive behaviours.

    Science.gov (United States)

    O'Sullivan, Sean S; Wu, Kit; Politis, Marios; Lawrence, Andrew D; Evans, Andrew H; Bose, Subrata K; Djamshidian, Atbin; Lees, Andrew J; Piccini, Paola

    2011-04-01

    Impulsive-compulsive behaviours are a significant source of morbidity for patients with Parkinson's disease receiving dopaminergic therapy. The development of these behaviours may reflect sensitization of the neural response to non-drug rewards, similar to that proposed for sensitization to drug rewards in addiction. Here, by using (11)C-raclopride positron emission tomography imaging, we investigated the effects of reward-related cues and L-dopa challenge in patients with Parkinson's disease with and without impulsive-compulsive behaviours on striatal levels of synaptic dopamine. Eighteen patients (11 with and seven without impulsive-compulsive behaviours) underwent three (11)C-raclopride positron emission tomography scans. The impulsive-compulsive behaviours included hypersexuality, binge eating, punding, compulsive use of dopamine replacement therapy, compulsive buying and pathological gambling, with eight patients exhibiting more than one impulsive-compulsive behaviour. There were no significant differences in baseline dopamine D2 receptor availability between the Parkinson's disease groups. No differences were found when comparing the percentage change of raclopride binding potential between the two Parkinson's disease groups following L-dopa challenge with neutral cues. The group with Parkinson's disease with impulsive-compulsive behaviours had a greater reduction of ventral striatum (11)C-raclopride binding potential following reward-related cue exposure, relative to neutral cue exposure, following L-dopa challenge (16.3% compared with 5.8% in Parkinson's disease controls, P = 0.016). The heightened response of striatal reward circuitry to heterogeneous reward-related visual cues among a group of patients with different impulsive-compulsive behaviours is consistent with a global sensitization to appetitive behaviours with dopaminergic therapy in vulnerable individuals. Our findings are relevant for the broader debate on the relation between impulsive

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

    Science.gov (United States)

    Van den Heuvel, O A; Van der Werf, Y D; Groenewegen, H J; Foncke, E M J; Berendse, H W

    2011-01-01

    Parkinson's disease is characterised not only by the classic triad of bradykinesia, rigidity and tremor, but also by the frequent occurrence of various non-motor symptoms such as the impulse control disorders (pathological gambling, hypersexuality, compulsive buying, binge eating, punding and dopamine dependency). To increase insight into the clinical presentation, risk factors, treatment and the underlying pathophysiological mechanisms of impulse control disorders in Parkinson's disease. Relevant literature was reviewed. Impulse control disorders belong to an important group of neuropsychiatric disorders that occur at some point in 5-10% of patients with Parkinson's disease. They generally occur in conjunction with dopaminergic medication and can have a marked social, relational and/ or financial impact. Early recognition of impulse control disorders in Parkinson's disease is important and a close collaboration between the neurologist and the psychiatrist is essential in order to ensure correct diagnosis and the best possible treatment. Impulse control disorders in Parkinson's disease show considerable phenomenological overlap with other repetitive behaviours within the impulsive-compulsive spectrum of disorders to which the obsessive-compulsive disorders and addiction disorders belong. The overlap can possibly be explained by a shared pathophysiological mechanism involving an imbalance between the direct and indirect pathways of the dorsal and ventral frontal-striatal circuits.

  2. Divergent responses of the amygdala and ventral striatum predict stress-related problem drinking in young adults: Possible differential markers of affective and impulsive pathways of risk for alcohol use disorder

    Science.gov (United States)

    Nikolova, Yuliya S.; Knodt, Annchen R.; Radtke, Spenser R.; Hariri, Ahmad R.

    2015-01-01

    Prior work suggests there may be two distinct pathways of alcohol use disorder (AUD) risk: one associated with positive emotion enhancement and behavioral impulsivity, and one associated with negative emotion relief and coping. We sought to map these two pathways onto individual differences in neural reward and threat processing assessed using BOLD fMRI in a sample of 759 undergraduate students (426 women, mean age 19.65±1.24) participating in the Duke Neurogenetics Study. We demonstrate that problem drinking is highest in the context of stress and in those with one of two distinct neural phenotypes: 1) a combination of relatively low reward-related activity of the ventral striatum (VS) and high threat-related reactivity of the amygdala; or 2) a combination of relatively high VS activity and low amygdala reactivity. In addition, we demonstrate that the relationship between stress and problem alcohol use is mediated by impulsivity, as reflected in monetary delay discounting rates, for those with high VS-low amygdala reactivity, and by anxious/depressive symptomatology for those with the opposite neural risk phenotype. Across both neural phenotypes, we found that greater divergence between VS and amygdala reactivity predicted greater risk for problem drinking. Finally, for those individuals with the low VS-high amygdala risk phenotype we found that stress not only predicted the presence of a DSM-IV diagnosed AUD at the time of neuroimaging, but also subsequent problem drinking reported three months following study completion. These results offer new insight into the neural basis of AUD risk and suggest novel biological targets for early individualized treatment or prevention. PMID:26122584

  3. Impulsivity and Concussion in Juvenile Rats: Examining Molecular and Structural Aspects of the Frontostriatal Pathway.

    Directory of Open Access Journals (Sweden)

    Harleen Hehar

    Full Text Available Impulsivity and poor executive control have been implicated in the pathogenesis of many developmental and neuropsychiatric disorders. Similarly, concussions/mild traumatic brain injuries (mTBI have been associated with increased risk for neuropsychiatric disorders and the development of impulsivity and inattention. Researchers and epidemiologists have therefore considered whether or not concussions induce symptoms of attention-deficit/hyperactivity disorder (ADHD, or merely unmask impulsive tendencies that were already present. The purpose of this study was to determine if a single concussion in adolescence could induce ADHD-like impulsivity and impaired response inhibition, and subsequently determine if inherent impulsivity prior to a pediatric mTBI would exacerbate post-concussion symptomology with a specific emphasis on impulsive and inattentive behaviours. As these behaviours are believed to be associated with the frontostriatal circuit involving the nucleus accumbens (NAc and the prefrontal cortex (PFC, the expression patterns of 8 genes (Comt, Drd2, Drd3, Drd4, Maoa, Sert, Tph1, and Tph2 from these two regions were examined. In addition, Golgi-Cox staining of medium spiny neurons in the NAc provided a neuroanatomical examination of mTBI-induced structural changes. The study found that a single early brain injury could induce impulsivity and impairments in response inhibition that were more pronounced in males. Interestingly, when animals with inherent impulsivity experienced mTBI, injury-related deficits were exacerbated in female animals. The single concussion increased dendritic branching, but reduced synaptic density in the NAc, and these changes were likely associated with the increase in impulsivity. Finally, mTBI-induced impulsivity was associated with modifications to gene expression that differed dramatically from the gene expression pattern associated with inherent impulsivity, despite very similar behavioural phenotypes. Our

  4. Increased impulsivity as a vulnerability marker for bipolar disorder: evidence from self-report and experimental measures in two high-risk populations.

    Science.gov (United States)

    Wessa, Michèle; Kollmann, Bianca; Linke, Julia; Schönfelder, Sandra; Kanske, Philipp

    2015-06-01

    Heightened impulsivity has been suggested as a possible risk factor for bipolar disorder (BD). However, studies on high-risk populations are scarce and have mainly focused on individuals with a genetic risk. The present study investigated two high-risk samples for BD with regard to several aspects of the impulsivity construct. Unaffected relatives of BD patients (genetically defined high-risk group, N=29) and participants scoring high on the Hypomanic Personality Scale (psychometrically defined high-risk sample, N=25) were being compared to respective control groups (N=27 and N=25) using a multi-method approach. Participants were accessed on the Barratt Impulsiveness Scale-11 (BIS-11, trait impulsivity), the Stop Signal Task (response inhibition), and the Cambridge Gambling Task (impulsive behavior in decision-making processes). Both high-risk groups reported heightened impulsivity on the BIS-11, as well as impulsive decision-making, whereas no significant group differences in response inhibition were observed. Limitations were the lack in specificity of the results for BD and the cross-sectional study design, which does not allow conclusions about the influence of impulsivity on the development of or resilience for BD in risk groups. Our findings support the assumption that increased trait impulsivity and impulsive decision-making are a vulnerability marker for and an endophenotype of BD. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    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.

  6. Impulse control disorders in women with eating disorders.

    Science.gov (United States)

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

    2008-01-15

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

  7. Impulsivity and Behaviour Problems in Dogs: A Reinforcement Sensitivity Theory Perspective.

    Science.gov (United States)

    Piotti, Patrizia; Satchell, Liam Paul; Lockhart, Tom Steven

    2018-03-09

    Trait impulsivity is an increasingly relevant topic for human and non-human animal personality research. There are similarities in dog and human manifestations of trait impulsivity at the behavioural, genetic, and neurobiological level. We investigated a well-validated measure of dog impulsivity and responsivity (the Dog Impulsivity Assessment Scale, DIAS) and a neuropsychological theory of human trait approach and avoidance (the Reinforcement Sensitivity Theory of personality, RST). Owners reported their dogs' dispositional behaviour on the DIAS, an RST scale modified to describe dogs' behaviour, and a list of common dog behaviour problems. In a sample of 730 dogs, we observed convergence between the RST and the DIAS. There was a negative correlation between RST 'Behaviour Inhibition System' and DIAS impulsivity factor ('Behavioural Regulation'). RST 'Behavioural Approach System' correlated positively with DIAS 'Responsiveness'. The RST 'Fight-Flight-Freeze System' (FFFS) and the DIAS 'Aggression and response to novelty factor were both distinct from other factors. However, the DIAS 'Aggression and response to novelty' factor and the RST FFFS explained different aspects of dog behaviour problems. Importantly, whilst the DIAS factors indicated tendencies towards avoidant behaviours, the FFFS discriminated between active and passive avoidance. The findings suggest a partial overlapping between the DIAS and RST scales, and highlights the utility of personality models in investigating behaviour problems in dogs. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Relationship between size summation properties, contrast sensitivity and response latency in the dorsomedial and middle temporal areas of the primate extrastriate cortex.

    Directory of Open Access Journals (Sweden)

    Leo L Lui

    Full Text Available Analysis of the physiological properties of single neurons in visual cortex has demonstrated that both the extent of their receptive fields and the latency of their responses depend on stimulus contrast. Here, we explore the question of whether there are also systematic relationships between these response properties across different cells in a neuronal population. Single unit recordings were obtained from the middle temporal (MT and dorsomedial (DM extrastriate areas of anaesthetized marmoset monkeys. For each cell, spatial integration properties (length and width summation, as well as the presence of end- and side-inhibition within 15° of the receptive field centre were determined using gratings of optimal direction of motion and spatial and temporal frequencies, at 60% contrast. Following this, contrast sensitivity was assessed using gratings of near-optimal length and width. In both areas, we found a relationship between spatial integration and contrast sensitivity properties: cells that summated over smaller areas of the visual field, and cells that displayed response inhibition at larger stimulus sizes, tended to show higher contrast sensitivity. In a sample of MT neurons, we found that cells showing longer latency responses also tended to summate over larger expanses of visual space in comparison with neurons that had shorter latencies. In addition, longer-latency neurons also tended to show less obvious surround inhibition. Interestingly, all of these effects were stronger and more consistent with respect to the selectivity for stimulus width and strength of side-inhibition than for length selectivity and end-inhibition. The results are partially consistent with a hierarchical model whereby more extensive receptive fields require convergence of information from larger pools of "feedforward" afferent neurons to reach near-optimal responses. They also suggest that a common gain normalization mechanism within MT and DM is involved, the

  9. Breakdown in short rod-plane air gaps under positive lightning impulse stress

    OpenAIRE

    Hygen Meyer, Hans Kristian; Mauseth, Frank; Pedersen, Per Atle; Martine, Husøy

    2017-01-01

    Prediction of withstand voltages in air-insulated systems are made on the basis of empirical models that are not sufficiently accurate for complex geometries. Bet-ter understanding of the spatio temporal development of electrical discharges is necessary to improve the present models. Discharges in lightning impulse stressed 20–100 mmrod-plane gaps are examined using a high-speed camera, photo-multiplier tubes (PMTs) and a high-bandwidth current measurement syste...

  10. Oscillatory activity in the medial prefrontal cortex and nucleus accumbens correlates with impulsivity and reward outcome.

    Directory of Open Access Journals (Sweden)

    Nicholas A Donnelly

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

  11. An Assessment of the Spatial and Temporal Variability of Biological Responses to Municipal Wastewater Effluent in Rainbow Darter (Etheostoma caeruleum) Collected along an Urban Gradient

    Science.gov (United States)

    Bragg, Leslie M.; Tetreault, Gerald R.; Bahamonde, Paulina A.; Tanna, Rajiv N.; Bennett, Charles J.; McMaster, Mark E.; Servos, Mark R.

    2016-01-01

    Municipal wastewater effluent (MWWE) and its constituents, such as chemicals of emerging concern, pose a potential threat to the sustainability of fish populations by disrupting key endocrine functions in aquatic organisms. While studies have demonstrated changes in biological markers of exposure of aquatic organisms to groups of chemicals of emerging concern, the variability of these markers over time has not been sufficiently described in wild fish species. The aim of this study was to assess the spatial and temporal variability of biological markers in response to MWWE exposure and to test the consistency of these responses between seasons and among years. Rainbow darter (Etheostoma caeruleum) were collected in spring and fall seasons over a 5-year period in the Grand River, Ontario, Canada. In addition to surface water chemistry (nutrients and selected pharmaceuticals), measures were taken across levels of biological organization in rainbow darter. The measurements of hormone production, gonad development, and intersex severity were temporally consistent and suggested impaired reproduction in male fish collected downstream of MWWE outfalls. In contrast, ovarian development and hormone production in females appeared to be influenced more by urbanization than MWWE. Measures of gene expression and somatic indices were highly variable between sites and years, respectively, and were inconclusive in terms of the impacts of MWWE overall. Robust biomonitoring programs must consider these factors in both the design and interpretation of results, especially when spatial and temporal sampling of biological endpoints is limited. Assessing the effects of contaminants and other stressors on fish in watersheds would be greatly enhanced by an approach that considers natural variability in the endpoints being measured. PMID:27776151

  12. An Assessment of the Spatial and Temporal Variability of Biological Responses to Municipal Wastewater Effluent in Rainbow Darter (Etheostoma caeruleum Collected along an Urban Gradient.

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    Meghan L M Fuzzen

    Full Text Available Municipal wastewater effluent (MWWE and its constituents, such as chemicals of emerging concern, pose a potential threat to the sustainability of fish populations by disrupting key endocrine functions in aquatic organisms. While studies have demonstrated changes in biological markers of exposure of aquatic organisms to groups of chemicals of emerging concern, the variability of these markers over time has not been sufficiently described in wild fish species. The aim of this study was to assess the spatial and temporal variability of biological markers in response to MWWE exposure and to test the consistency of these responses between seasons and among years. Rainbow darter (Etheostoma caeruleum were collected in spring and fall seasons over a 5-year period in the Grand River, Ontario, Canada. In addition to surface water chemistry (nutrients and selected pharmaceuticals, measures were taken across levels of biological organization in rainbow darter. The measurements of hormone production, gonad development, and intersex severity were temporally consistent and suggested impaired reproduction in male fish collected downstream of MWWE outfalls. In contrast, ovarian development and hormone production in females appeared to be influenced more by urbanization than MWWE. Measures of gene expression and somatic indices were highly variable between sites and years, respectively, and were inconclusive in terms of the impacts of MWWE overall. Robust biomonitoring programs must consider these factors in both the design and interpretation of results, especially when spatial and temporal sampling of biological endpoints is limited. Assessing the effects of contaminants and other stressors on fish in watersheds would be greatly enhanced by an approach that considers natural variability in the endpoints being measured.

  13. Impulsivity and aggression in schizophrenia: a neural circuitry perspective with implications for treatment.

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    Hoptman, Matthew J

    2015-06-01

    Elevations of impulsive behavior have been observed in a number of serious mental illnesses. These phenomena can lead to harmful behaviors, including violence, and thus represent a serious public health concern. Such violence is often a reason for psychiatric hospitalization, and it often leads to prolonged hospital stays, suffering by patients and their victims, and increased stigmatization. Despite the attention paid to violence, little is understood about its neural basis in schizophrenia. On a psychological level, aggression in schizophrenia has been primarily attributed to psychotic symptoms, desires for instrumental gain, or impulsive responses to perceived personal slights. Often, multiple attributions can coexist during a single aggressive incident. In this review, I discuss the neural circuitry associated with impulsivity and aggression in schizophrenia, with an emphasis on implications for treatment. Impulsivity appears to account for a great deal of aggression in schizophrenia, especially in inpatient settings. Urgency, defined as impulsivity in the context of strong emotion, is the primary focus of this article. It is elevated in several psychiatric disorders, and in schizophrenia, it has been related to aggression. Many studies have implicated dysfunctional frontotemporal circuitry in impulsivity and aggression in schizophrenia, and pharmacological treatments may act via that circuitry to reduce urgency and aggressive behaviors; however, more mechanistic studies are critically needed. Recent studies point toward manipulable neurobehavioral targets and suggest that cognitive, pharmacological, neuromodulatory, and neurofeedback treatment approaches can be developed to ameliorate urgency and aggression in schizophrenia. It is hoped that these approaches will improve treatment efficacy.

  14. Endogenous acetylcholine modulates impulsive action via alpha4beta2 nicotinic acetylcholine receptors in rats.

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

    2010-09-01

    Nicotine has been well established as an impulsive action-inducing agent, but it remains unknown whether endogenous acetylcholine affects impulsive action via nicotinic acetylcholine receptors. In the present study, the 3-choice serial reaction time task (3-CSRTT), a simple and valid assessment of impulsive action, was employed. Male Wistar/ST rats were trained to detect and respond to 1-s flashes of light presented in one of three holes until stable performance was achieved. Following training on the 3-CSRTT, rats received intracerebroventricular injections of the preferential alpha4beta2 nicotinic acetylcholine receptor antagonist dihydro-beta-erythroidine (DHbetaE; 0, 3, 10, and 30 microg) or the selective alpha7 nicotinic acetylcholine receptor antagonist methyllycaconitine (MLA; 0, 3, 10, and 30 microg) 5 min before test sessions. Injection of 10 microg of DHbetaE significantly suppressed premature responses, an index of impulsive-like action, without changing other behavioral parameters. On the other hand, MLA infusions failed to affect impulsive-like action at any dose. These results suggest that the central alpha4beta2 nicotinic acetylcholine receptors that enable a provoking effect of endogenous acetylcholine play a critical role in impulsive action. Substances that modulate nicotinic acetylcholine receptors, especially the alpha4beta2 subtype, may be beneficial for the treatment of psychiatric disorders characterized by lack of inhibitory control. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  15. Neural connectivity moderates the association between sleep and impulsivity in adolescents

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    Sarah M. Tashjian

    2017-10-01

    Full Text Available Adolescence is characterized by chronic insufficient sleep and extensive brain development, but the relation between adolescent sleep and brain function remains unclear. We report the first functional magnetic resonance imaging study to investigate functional connectivity as a moderator between sleep and impulsivity, a problematic behavior during this developmental period. Naturalistic differences in sleep have not yet been explored as treatable contributors to adolescent impulsivity. Although public and scientific attention focuses on sleep duration, we report individual differences in sleep quality, not duration, in fifty-five adolescents (ages 14–18 yielded significant differences in functional connectivity between the prefrontal cortex and default mode network. Poor sleep quality was related to greater affect-related impulsivity among adolescents with low, but not high, connectivity, suggesting neural functioning relates to individual differences linking sleep quality and impulsivity. Response inhibition and cognitive impulsivity were not related to sleep quality, suggesting that sleep has a greater impact on affect-related impulsivity. Exploring environmental contributors of poor sleep quality, we demonstrated pillow comfort was uniquely related to sleep quality over age, sex, and income, a promising advance ripe for intervention.

  16. Examination of the heterogeneity in PTSD and impulsivity facets: A latent profile analysis.

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    Contractor, Ateka A; Caldas, Stephanie; Weiss, Nicole H; Armour, Cherie

    2018-04-15

    The experience of traumatizing events and resulting posttraumatic stress disorder (PTSD) symptomology relates to a range of impulsive behaviors. While both PTSD and impulsivity are heterogeneous and multidimensional constructs, no research has used person-centered approaches to examine subgroups of individuals based on these response endorsements. Hence, our study examined PTSD-impulsivity typologies and their construct validity in two samples: university students ( n = 412) and community participants recruited through Amazon's MTurk ( n = 346). Measures included the Stressful Life Events Screening Questionnaire (PTEs), PTSD Checklist for DSM-5 (PTSD severity), UPPS Impulsive Behavior Scale (negative urgency, lack of premeditation, lack of perseverance, sensation seeking). Dimensions of Anger Reaction Scale (anger), and the Patient Health Questionnaire-9 (depression). For both samples, results of latent profile analyses indicated a best-fitting 3-class solution: High, Moderate, and Low PTSD-Negative Urgency. Negative urgency was the most distinguishing impulsivity facet. Anger and depression severity significantly predicted membership in the more severe symptomatology classes. Thus, individuals can be meaningfully categorized into three subgroups based on PTSD and impulsivity item endorsements. We provide some preliminary evidence for a negative urgency subtype of PTSD characterized by greater depression and anger regulation difficulties; and underscore addressing emotional regulation skills for these subgroup members.

  17. Convergent pharmacological mechanisms in impulsivity and addiction: insights from rodent models.

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    Jupp, B; Dalley, J W

    2014-10-01

    Research over the last two decades has widely demonstrated that impulsivity, in its various forms, is antecedent to the development of drug addiction and an important behavioural trait underlying the inability of addicts to refrain from continued drug use. Impulsivity describes a variety of rapidly and prematurely expressed behaviours that span several domains from impaired response inhibition to an intolerance of delayed rewards, and is a core symptom of attention deficit hyperactivity disorder (ADHD) and other brain disorders. Various theories have been advanced to explain how impulsivity interacts with addiction both causally and as a consequence of chronic drug abuse; these acknowledge the strong overlaps in neural circuitry and mechanisms between impulsivity and addiction and the seemingly paradoxical treatment of ADHD with stimulant drugs with high abuse potential. Recent years have witnessed unprecedented progress in the elucidation of pharmacological mechanisms underpinning impulsivity. Collectively, this work has significantly improved the prospect for new therapies in ADHD as well as our understanding of the neural mechanisms underlying the shift from recreational drug use to addiction. In this review, we consider the extent to which pharmacological interventions that target impulsive behaviour are also effective in animal models of addiction. We highlight several promising examples of convergence based on empirical findings in rodent-based studies. © 2014 The British Pharmacological Society.

  18. The Effect of Visual Merchandising on Impulsive Buying with Impulsive Buying Tendency As Moderating Variable

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    Jessica Novia

    2015-03-01

    Full Text Available This research aims to classify the female consumer demographic segments linked by impulsive buying, to determine the effect of visual merchandising on impulsive buying, and to determine the effect of visual merchandising on impulsive buying with impulsive buying tendency as moderating variable on customers of Gaudi in Taman Anggrek Mall. This research is quantitative research with a total sample of 100 people. Data were obtained by distributing questionnaires to the respondents by cross sectional. Research used Cluster Analysis and Moderated Regression Analysis. Data processing was performed using SPSS software for Windows version 20. Research found that customers of Gaudi were divided into three groups: the way of the world, sufficient money, and promotions. Then, research found that visual merchandising affected impulsive buying. In addition, there visual merchandising had also an effect on impulsive buying with impulsive buying tendency as moderating variable. As a conclusion, moderating variable strengthens the effect of visual merchandising on impulse buying.

  19. The relationship between impulsivity and impulse control disorders in Parkinson's disease.

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    Isaias, Ioannis U; Siri, Chiara; Cilia, Roberto; De Gaspari, Danilo; Pezzoli, Gianni; Antonini, Angelo

    2008-02-15

    A range of behaviors presumed to be related to dopaminergic medications have been recently recognized in Parkinson's disease (PD). We evaluated 50 consecutive cognitively intact PD patients on stable dopamine agonist and levodopa therapy and 100 healthy controls for compulsive sexual behavior, compulsive buying, or intermittent explosive disorders assessed by the Minnesota Impulsive Disorders Interview (MIDI), pathological gambling (South Oaks Gambling Screen, SOGS), impulsivity (Barratt Impulsiveness Scale), compulsivity (Maudsley obsessional-compulsive inventory), and depression scores (Geriatric Depression Scale). Overall 28% PD (14/50) and 20% healthy controls (20/100) reported at least one abnormal behavior at MIDI or pathological SOGS score. PD patients had higher scores than controls for impulsivity (P = 0.006), compulsivity (P compulsivity, and depression scores in PD. Male gender and higher impulsivity score, but not dose and kind of dopaminergic medications, were associated in PD with increased probability of impulsive disorders at MIDI. Impulse control disorders are also common in the control population. Individual susceptibility factors, such as high impulsivity and depression, underline abnormal behaviors in PD patients treated with stable dopaminergic therapy. 2007 Movement Disorder Society

  20. Increased impulsivity retards the transition to dorsolateral striatal dopamine control of cocaine seeking.

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    Murray, Jennifer E; Dilleen, Ruth; Pelloux, Yann; Economidou, Daina; Dalley, Jeffrey W; Belin, David; Everitt, Barry J

    2014-07-01

    Development of maladaptive drug-seeking habits occurs in conjunction with a ventral-to-dorsal striatal shift in dopaminergic control over behavior. Although these habits readily develop as drug use continues, high impulsivity predicts loss of control over drug seeking and taking. However, whether impulsivity facilitates the transition to dorsolateral striatum (DLS) dopamine-dependent cocaine-seeking habits or whether impulsivity and cocaine-induced intrastriatal shifts are additive processes is unknown. High- and low-impulsive rats identified in the five-choice serial reaction-time task were trained to self-administer cocaine (.25 mg/infusion) with infusions occurring in the presence of a cue-light conditioned stimulus. Dopamine transmission was blocked in the DLS after three stages of training: early, transition, and late-stage, by bilateral intracranial infusions of α-flupenthixol (0, 5, 10, or 15 μg/side) during 15-min cocaine-seeking test sessions in which each response was reinforced by a cocaine-associated conditioned stimulus presentation. In early-stage tests, neither group was affected by DLS dopamine receptor blockade. In transition-stage tests, low-impulsive rats showed a significant dose-dependent reduction in cocaine seeking, whereas high-impulsive rats were still unaffected by α-flupenthixol infusions. In the final, late-stage seeking test, both groups showed dose-dependent sensitivity to dopamine receptor blockade. The results demonstrate that high impulsivity is associated with a delayed transition to DLS-dopamine-dependent control over cocaine seeking. This suggests that, if impulsivity confers an increased propensity to addiction, it is not simply through a more rapid development of habits but instead through interacting corticostriatal and striato-striatal processes that result ultimately in maladaptive drug-seeking habits. © 2013 Society of Biological Psychiatry Published by Society of Biological Psychiatry All rights reserved.