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Sample records for shock 4degc evokes

  1. Scent-evoked nostalgia.

    Reid, Chelsea A; Green, Jeffrey D; Wildschut, Tim; Sedikides, Constantine

    2015-01-01

    Can scents evoke nostalgia; what might be the psychological implications of such an evocation? Participants sampled 12 scents and rated the extent to which each scent was familiar, arousing and autobiographically relevant, as well as the extent to which each scent elicited nostalgia. Participants who were high (compared to low) in nostalgia proneness reported more scent-evoked nostalgia, and scents elicited greater nostalgia to the extent that they were arousing, familiar and autobiographically relevant. Scent-evoked nostalgia predicted higher levels of positive affect, self-esteem, self-continuity, optimism, social connectedness and meaning in life. In addition, scent-evoked nostalgia was characterised by more positive emotions than either non-nostalgic autobiographical memories or non-nostalgic non-autobiographical memories. Finally, scent-evoked nostalgia predicted in-the-moment feelings of personal (general or object-specific) nostalgia. The findings represent a foray into understanding the triggers and affective signature of scent-evoked nostalgia.

  2. Proprioceptive evoked gamma oscillations

    Arnfred, S.M.; Hansen, Lars Kai; Parnas, J.

    2007-01-01

    A proprioceptive stimulus consisting of a weight change of a handheld load has recently been shown to elicit an evoked potential. Previously, somatosensory gamma oscillations have only been evoked by electrical stimuli. We conjectured that a natural proprioceptive stimulus also would be able...... to evoke gamma oscillations. EEG was recorded using 64 channels in 14 healthy subjects. In each of three runs a stimulus of 100 g load increment in each hand was presented in 120 trials. Data were wavelet transformed and runs collapsed. Inter-trial phase coherence (ITPC) was computed as the best measure...

  3. Adverse Weather Evokes Nostalgia.

    van Tilburg, Wijnand A P; Sedikides, Constantine; Wildschut, Tim

    2018-03-01

    Four studies examined the link between adverse weather and the palliative role of nostalgia. We proposed and tested that (a) adverse weather evokes nostalgia (Hypothesis 1); (b) adverse weather causes distress, which predicts elevated nostalgia (Hypothesis 2); (c) preventing nostalgia exacerbates weather-induced distress (Hypothesis 3); and (d) weather-evoked nostalgia confers psychological benefits (Hypothesis 4). In Study 1, participants listened to recordings of wind, thunder, rain, and neutral sounds. Adverse weather evoked nostalgia. In Study 2, participants kept a 10-day diary recording weather conditions, distress, and nostalgia. We also obtained meteorological data. Adverse weather perceptions were positively correlated with distress, which predicted higher nostalgia. Also, adverse natural weather was associated with corresponding weather perceptions, which predicted elevated nostalgia. (Results were mixed for rain.) In Study 3, preventing nostalgia (via cognitive load) increased weather-evoked distress. In Study 4, weather-evoked nostalgia was positively associated with psychological benefits. The findings pioneer the relevance of nostalgia as source of comfort in adverse weather.

  4. Evoked acoustic emission

    Elberling, C; Parbo, J; Johnsen, N J

    1985-01-01

    Stimulated acoustic emissions were recorded in response to tonal stimuli at 60 dB p.e. SPL in a small group of normal-hearing adults. Power spectral analysis reveals that the evoked activity from each ear contains energy in preferential frequency bands and the change of stimulus frequency has only...

  5. International Evoked Potentials Symposium

    1980-01-01

    The past decade has seen great progress in the measurement of evoked potentials in man; a steady increase in our understanding of their charac­ teristics, their origins and their usefulness; and a growing application in the field of clinical diagnosis. The topic is a truly multidisciplinary one. Important research contributions have been made by workers of many different backgrounds and clinical applications span the specialities. This book represents a revised and updated version of the work originally presented at the international evoked potential symposium held in Nottingham 4-6 1978. The Nottingham Symposium provided a forum for a state-of-the-art discussion amongst workers from many different disciplines and from many different countries. For each major topic in the field an expert review set the scene for discussion of current research presentations. This format is retained in the book: the chapters in Part A provide the context in which the research presented in Part B is set. The task of selecting m...

  6. Music evokes vivid autobiographical memories.

    Belfi, Amy M; Karlan, Brett; Tranel, Daniel

    2016-08-01

    Music is strongly intertwined with memories-for example, hearing a song from the past can transport you back in time, triggering the sights, sounds, and feelings of a specific event. This association between music and vivid autobiographical memory is intuitively apparent, but the idea that music is intimately tied with memories, seemingly more so than other potent memory cues (e.g., familiar faces), has not been empirically tested. Here, we compared memories evoked by music to those evoked by famous faces, predicting that music-evoked autobiographical memories (MEAMs) would be more vivid. Participants listened to 30 songs, viewed 30 faces, and reported on memories that were evoked. Memories were transcribed and coded for vividness as in Levine, B., Svoboda, E., Hay, J. F., Winocur, G., & Moscovitch, M. [2002. Aging and autobiographical memory: Dissociating episodic from semantic retrieval. Psychology and Aging, 17, 677-689]. In support of our hypothesis, MEAMs were more vivid than autobiographical memories evoked by faces. MEAMs contained a greater proportion of internal details and a greater number of perceptual details, while face-evoked memories contained a greater number of external details. Additionally, we identified sex differences in memory vividness: for both stimulus categories, women retrieved more vivid memories than men. The results show that music not only effectively evokes autobiographical memories, but that these memories are more vivid than those evoked by famous faces.

  7. Evoked emotions predict food choice.

    Dalenberg, Jelle R; Gutjar, Swetlana; Ter Horst, Gert J; de Graaf, Kees; Renken, Remco J; Jager, Gerry

    2014-01-01

    In the current study we show that non-verbal food-evoked emotion scores significantly improve food choice prediction over merely liking scores. Previous research has shown that liking measures correlate with choice. However, liking is no strong predictor for food choice in real life environments. Therefore, the focus within recent studies shifted towards using emotion-profiling methods that successfully can discriminate between products that are equally liked. However, it is unclear how well scores from emotion-profiling methods predict actual food choice and/or consumption. To test this, we proposed to decompose emotion scores into valence and arousal scores using Principal Component Analysis (PCA) and apply Multinomial Logit Models (MLM) to estimate food choice using liking, valence, and arousal as possible predictors. For this analysis, we used an existing data set comprised of liking and food-evoked emotions scores from 123 participants, who rated 7 unlabeled breakfast drinks. Liking scores were measured using a 100-mm visual analogue scale, while food-evoked emotions were measured using 2 existing emotion-profiling methods: a verbal and a non-verbal method (EsSense Profile and PrEmo, respectively). After 7 days, participants were asked to choose 1 breakfast drink from the experiment to consume during breakfast in a simulated restaurant environment. Cross validation showed that we were able to correctly predict individualized food choice (1 out of 7 products) for over 50% of the participants. This number increased to nearly 80% when looking at the top 2 candidates. Model comparisons showed that evoked emotions better predict food choice than perceived liking alone. However, the strongest predictive strength was achieved by the combination of evoked emotions and liking. Furthermore we showed that non-verbal food-evoked emotion scores more accurately predict food choice than verbal food-evoked emotions scores.

  8. Shock absorber

    Nemeth, J.D.

    1981-01-01

    A shock absorber for the support of piping and components in a nuclear power plant is described. It combines a high degree of stiffness under sudden shocks, e.g. seismic disturbances, with the ability to allow for thermal expansion without resistance when so required. (JIW)

  9. demystifying the shock of shocking

    (with a pulse), atrial fibrillation and atrial flutter. The energy dose in cardioversion is less (0.5. - 2 J/kg) than in defibrillation (2 - 4 J/kg). In cardioversion the shock is discharged synchronously with the native R wave of the patient. Without synchronisation,. VF can be induced if a shock is delivered during the refractory period ...

  10. Evoked Emotions Predict Food Choice

    Dalenberg, Jelle R.; Gutjar, Swetlana; ter Horst, Gert J.; de Graaf, Kees; Renken, Remco J.; Jager, Gerry

    2014-01-01

    In the current study we show that non-verbal food-evoked emotion scores significantly improve food choice prediction over merely liking scores. Previous research has shown that liking measures correlate with choice. However, liking is no strong predictor for food choice in real life environments.

  11. Hypovolemic shock

    ... the person's position unless they are in immediate danger. Do not give fluids by mouth. If person ... the patient with shock. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine . 25th ed. Philadelphia, PA: ...

  12. Shock absorber

    Housman, J.J.

    1978-01-01

    A shock absorber is described for use in a hostile environment at the end of a blind passage for absorbing impact loads. The shock absorber includes at least one element which occupies the passage and which is comprised of a porous brittle material which is substantially non-degradable in the hostile environment. A void volume is provided in the element to enable the element to absorb a predetermined level of energy upon being crushed due to impact loading

  13. Noise-evoked otoacoustic emissions in humans

    Maat, B; Wit, HP; van Dijk, P

    2000-01-01

    Click-evoked otoacoustic emissions (CEOAEs) and acoustical responses evoked by bandlimited Gaussian noise (noise-evoked otoacoustic emissions; NEOAEs) were measured in three normal-hearing subjects. For the NEOAEs the first- and second-order Wiener kernel and polynomial correlation functions up to

  14. Evoked Emotions Predict Food Choice

    Dalenberg, Jelle R.; Gutjar, Swetlana; ter Horst, Gert J.; de Graaf, Kees; Renken, Remco J.; Jager, Gerry

    2014-01-01

    In the current study we show that non-verbal food-evoked emotion scores significantly improve food choice prediction over merely liking scores. Previous research has shown that liking measures correlate with choice. However, liking is no strong predictor for food choice in real life environments. Therefore, the focus within recent studies shifted towards using emotion-profiling methods that successfully can discriminate between products that are equally liked. However, it is unclear how well ...

  15. Toxic shock syndrome

    Staphylococcal toxic shock syndrome; Toxic shock-like syndrome; TSLS ... Toxic shock syndrome is caused by a toxin produced by some types of staphylococcus bacteria. A similar problem, called toxic shock- ...

  16. Proprioceptive evoked potentials in man

    Arnfred, S; Chen, A C; Eder, Derek N

    2000-01-01

    We studied cerebral evoked potentials on the scalp to the stimulation of the right hand from a change in weight of 400-480 g in ten subjects. Rise-time was 20g/10 ms, Inter Stimulus Interval 2s and stimulus duration was 100 ms. The cerebral activations were a double positive contralateral C3'/P70......). Further studies of the PEP are needed to assess the influence of load manipulations and of muscle contraction and to explore the effect of attentional manipulation....

  17. Evoked Electromyographically Controlled Electrical Stimulation

    Mitsuhiro Hayashibe

    2016-07-01

    Full Text Available Time-variant muscle responses under electrical stimulation (ES are often problematic for all the applications of neuroprosthetic muscle control. This situation limits the range of ES usage in relevant areas, mainly due to muscle fatigue and also to changes in stimulation electrode contact conditions, especially in transcutaneous ES. Surface electrodes are still the most widely used in noninvasive applications.Electrical field variations caused by changes in the stimulation contact condition markedly affect the resulting total muscle activation levels. Fatigue phenomena under functional electrical stimulation (FES are also well known source of time-varying characteristics coming from muscle response under ES. Therefore it is essential to monitor the actual muscle state and assess the expected muscle response by ES so as to improve the current ES system in favour of adaptive muscle-response-aware FES control. To deal with this issue, we have been studying a novel control technique using evoked electromyography (eEMG signals to compensate for these muscle time-variances under ES for stable neuroprosthetic muscle control. In this perspective article, I overview the background of this topic and highlight important points to be aware of when using ES to induce the desired muscle activation regardless of the time-variance. I also demonstrate how to deal with the common critical problem of ES to move toward robust neuroprosthetic muscle control with the Evoked Electromyographically Controlled Electrical Stimulation paradigm.

  18. Shock Waves

    Jiang, Z

    2005-01-01

    The International Symposium on Shock Waves (ISSW) is a well established series of conferences held every two years in a different location. A unique feature of the ISSW is the emphasis on bridging the gap between physicists and engineers working in fields as different as gas dynamics, fluid mechanics and materials sciences. The main results presented at these meetings constitute valuable proceedings that offer anyone working in this field an authoritative and comprehensive source of reference.

  19. Running Reduces Uncontrollable Stress-Evoked Serotonin and Potentiates Stress-Evoked Dopamine Concentrations in the Rat Dorsal Striatum.

    Peter J Clark

    Full Text Available Accumulating evidence from both the human and animal literature indicates that exercise reduces the negative consequences of stress. The neurobiological etiology for this stress protection, however, is not completely understood. Our lab reported that voluntary wheel running protects rats from expressing depression-like instrumental learning deficits on the shuttle box escape task after exposure to unpredictable and inescapable tail shocks (uncontrollable stress. Impaired escape behavior is a result of stress-sensitized serotonin (5-HT neuron activity in the dorsal raphe (DRN and subsequent excessive release of 5-HT into the dorsal striatum following exposure to a comparatively mild stressor. However, the possible mechanisms by which exercise prevents stress-induced escape deficits are not well characterized. The purpose of this experiment was to test the hypothesis that exercise blunts the stress-evoked release of 5-HT in the dorsal striatum. Changes to dopamine (DA levels were also examined, since striatal DA signaling is critical for instrumental learning and can be influenced by changes to 5-HT activity. Adult male F344 rats, housed with or without running wheels for 6 weeks, were either exposed to tail shock or remained undisturbed in laboratory cages. Twenty-four hours later, microdialysis was performed in the medial (DMS and lateral (DLS dorsal striatum to collect extracellular 5-HT and DA before, during, and following 2 mild foot shocks. We report wheel running prevents foot shock-induced elevation of extracellular 5-HT and potentiates DA concentrations in both the DMS and DLS approximately 24 h following exposure to uncontrollable stress. These data may provide a possible mechanism by which exercise prevents depression-like instrumental learning deficits following exposure to acute stress.

  20. Shock Prevention

    1978-01-01

    The electrician pictured is installing a General Electric Ground Fault Interrupter (GFI), a device which provides protection against electrical shock in the home or in industrial facilities. Shocks due to defective wiring in home appliances or other electrical equipment can cause severe burns, even death. As a result, the National Electrical Code now requires GFIs in all new homes constructed. This particular type of GFI employs a sensing element which derives from technology acquired in space projects by SCI Systems, Inc., Huntsville, Alabama, producer of sensors for GE and other manufacturers of GFI equipment. The sensor is based on the company's experience in developing miniaturized circuitry for space telemetry and other spacecraft electrical systems; this experience enabled SCI to package interruptor circuitry in the extremely limited space available and to produce sensory devices at practicable cost. The tiny sensor measures the strength of the electrical current and detects current differentials that indicate a fault in the functioning of an electrical system. The sensing element then triggers a signal to a disconnect mechanism in the GFI, which cuts off the current in the faulty circuit.

  1. Collisionless electrostatic shocks

    Andersen, H.K.; Andersen, S.A.; Jensen, Vagn Orla

    1970-01-01

    An attempt was made in the laboratory to observe the standing collisionless electrostatic shocks in connection with the bow shock of the earth......An attempt was made in the laboratory to observe the standing collisionless electrostatic shocks in connection with the bow shock of the earth...

  2. Geometrical shock dynamics for magnetohydrodynamic fast shocks

    Mostert, W.; Pullin, D. I.; Samtaney, Ravi; Wheatley, V.

    2016-01-01

    We describe a formulation of two-dimensional geometrical shock dynamics (GSD) suitable for ideal magnetohydrodynamic (MHD) fast shocks under magnetic fields of general strength and orientation. The resulting area–Mach-number–shock-angle relation is then incorporated into a numerical method using pseudospectral differentiation. The MHD-GSD model is verified by comparison with results from nonlinear finite-volume solution of the complete ideal MHD equations applied to a shock implosion flow in the presence of an oblique and spatially varying magnetic field ahead of the shock. Results from application of the MHD-GSD equations to the stability of fast MHD shocks in two dimensions are presented. It is shown that the time to formation of triple points for both perturbed MHD and gas-dynamic shocks increases as (Formula presented.), where (Formula presented.) is a measure of the initial Mach-number perturbation. Symmetry breaking in the MHD case is demonstrated. In cylindrical converging geometry, in the presence of an azimuthal field produced by a line current, the MHD shock behaves in the mean as in Pullin et al. (Phys. Fluids, vol. 26, 2014, 097103), but suffers a greater relative pressure fluctuation along the shock than the gas-dynamic shock. © 2016 Cambridge University Press

  3. Geometrical shock dynamics for magnetohydrodynamic fast shocks

    Mostert, W.

    2016-12-12

    We describe a formulation of two-dimensional geometrical shock dynamics (GSD) suitable for ideal magnetohydrodynamic (MHD) fast shocks under magnetic fields of general strength and orientation. The resulting area–Mach-number–shock-angle relation is then incorporated into a numerical method using pseudospectral differentiation. The MHD-GSD model is verified by comparison with results from nonlinear finite-volume solution of the complete ideal MHD equations applied to a shock implosion flow in the presence of an oblique and spatially varying magnetic field ahead of the shock. Results from application of the MHD-GSD equations to the stability of fast MHD shocks in two dimensions are presented. It is shown that the time to formation of triple points for both perturbed MHD and gas-dynamic shocks increases as (Formula presented.), where (Formula presented.) is a measure of the initial Mach-number perturbation. Symmetry breaking in the MHD case is demonstrated. In cylindrical converging geometry, in the presence of an azimuthal field produced by a line current, the MHD shock behaves in the mean as in Pullin et al. (Phys. Fluids, vol. 26, 2014, 097103), but suffers a greater relative pressure fluctuation along the shock than the gas-dynamic shock. © 2016 Cambridge University Press

  4. Characterization of music-evoked autobiographical memories.

    Janata, Petr; Tomic, Stefan T; Rakowski, Sonja K

    2007-11-01

    Despite music's prominence in Western society and its importance to individuals in their daily lives, very little is known about the memories and emotions that are often evoked when hearing a piece of music from one's past. We examined the content of music-evoked autobiographical memories (MEAMs) using a novel approach for selecting stimuli from a large corpus of popular music, in both laboratory and online settings. A set of questionnaires probed the cognitive and affective properties of the evoked memories. On average, 30% of the song presentations evoked autobiographical memories, and the majority of songs also evoked various emotions, primarily positive, that were felt strongly. The third most common emotion was nostalgia. Analyses of written memory reports found both general and specific levels of autobiographical knowledge to be represented, and several social and situational contexts for memory formation were common across many memories. The findings indicate that excerpts of popular music serve as potent stimuli for studying the structure of autobiographical memories.

  5. Stress-evoked opioid release inhibits pain in major depressive disorder.

    Frew, Ashley K; Drummond, Peter D

    2008-10-15

    To determine whether stress-evoked release of endogenous opioids might account for hypoalgesia in major depressive disorder (MDD), the mu-opioid antagonist naltrexone (50mg) or placebo was administered double-blind to 24 participants with MDD and to 31 non-depressed controls. Eighty minutes later participants completed a painful foot cold pressor test and, after a 5-min interval, began a 25-min arithmetic task interspersed with painful electric shocks. Ten minutes later participants completed a second cold pressor test. Negative affect was greater in participants with MDD than in non-depressed controls throughout the experiment, and increased significantly in both groups during mental arithmetic. Before the math task, naltrexone unmasked direct linear relationships between severity of depression, negative affect while resting quietly, and cold-induced pain in participants with MDD. In contrast, facilitatory effects of naltrexone on cold- and shock-induced pain were greatest in controls with the lowest depression scores. Naltrexone strengthened the relationship between negative affect and shock-induced pain during the math task, particularly in the depressed group, and heightened anxiety in both groups toward the end of the task. Thus, mu-opioid activity apparently masked a positive association between negative affect and pain in the most distressed participants. These findings suggest that psychological distress inhibits pain via stress-evoked release of opioid peptides in severe cases of MDD. In addition, tonic endogenous opioid neurotransmission could inhibit depressive symptoms and pain in people with low depression scores.

  6. Brainstem evoked potentials in infantile spasms

    Miyazaki, Masahito; Hashimoto, Toshiaki; Murakawa, Kazuyoshi; Tayama, Masanobu; Kuroda, Yasuhiro

    1992-01-01

    In ten patients with infantile spasms, brainstem evoked potentials and MRI examinations were performed to evaluate the brainstem involvement. The result of short latency somatosensory evoked potentials (SSEP) following the right median nerve stimulation revealed abnormal findings including the absence or low amplitudes of the waves below wave P3 and delayed central conduction time in 7 of the ten patients. The result of auditory brainstem responses (ABR) revealed abnormal findings including low amplitudes of wave V, prolonged interpeak latency of waves I-V and absence of the waves below wave IV in 5 of the ten patients. The result of the MRI examinations revealed various degrees of the brainstem atrophy in 6 of the ten patients, all of whom showed abnormal brainstem evoked potentials. The result of this study demonstrates that patients with infantile spasms are frequently associated with brainstem dysfunction and raises the possibility that brainstem atrophy might be a cause of infantile spasms. (author)

  7. Slow cortical evoked potentials after noise exposure

    von Wedel, H; Opitz, H J

    1979-07-01

    Human cortical evoked potentials under conditions of stimuation are registrated in the post-stimulatory phase of a five minutes lasting equally masking white noise (90 dB HL). Changes of the evoked potentials during adaptation, possible analogy with high tone losses after noise representation and the origin of tinnitus are examined. Stimulation was started 3 sec after the off-effect of the noise. For five minutes periodically tone bursts were represented. Each train of stimulation consists of tone bursts of three frequencies: 2 kcs, 4 kcs, 8 kcs. The 0.5 sec lasting tones were separated by pauses of 2 sec. During the experiment stimulation and analysis were controlled by a computer. Changes in latency and amplitudes of the cortical evoked potentials were registered. Changes of the adaptation patterns as a function of the poststimulatory time are discussed.

  8. Evoking prescribed spike times in stochastic neurons

    Doose, Jens; Lindner, Benjamin

    2017-09-01

    Single cell stimulation in vivo is a powerful tool to investigate the properties of single neurons and their functionality in neural networks. We present a method to determine a cell-specific stimulus that reliably evokes a prescribed spike train with high temporal precision of action potentials. We test the performance of this stimulus in simulations for two different stochastic neuron models. For a broad range of parameters and a neuron firing with intermediate firing rates (20-40 Hz) the reliability in evoking the prescribed spike train is close to its theoretical maximum that is mainly determined by the level of intrinsic noise.

  9. Brain correlates of music-evoked emotions.

    Koelsch, Stefan

    2014-03-01

    Music is a universal feature of human societies, partly owing to its power to evoke strong emotions and influence moods. During the past decade, the investigation of the neural correlates of music-evoked emotions has been invaluable for the understanding of human emotion. Functional neuroimaging studies on music and emotion show that music can modulate activity in brain structures that are known to be crucially involved in emotion, such as the amygdala, nucleus accumbens, hypothalamus, hippocampus, insula, cingulate cortex and orbitofrontal cortex. The potential of music to modulate activity in these structures has important implications for the use of music in the treatment of psychiatric and neurological disorders.

  10. Miniature shock tube for laser driven shocks.

    Busquet, Michel; Barroso, Patrice; Melse, Thierry; Bauduin, Daniel

    2010-02-01

    We describe in this paper the design of a miniature shock tube (smaller than 1 cm(3)) that can be placed in a vacuum vessel and allows transverse optical probing and longitudinal backside extreme ultraviolet emission spectroscopy in the 100-500 A range. Typical application is the study of laser launched radiative shocks, in the framework of what is called "laboratory astrophysics."

  11. Are Credit Shocks Supply or Demand Shocks?

    Bijapur, Mohan

    2013-01-01

    This paper provides new insights into the relationship between the supply of credit and the macroeconomy. We present evidence that credit shocks constitute shocks to aggregate supply in that they have a permanent effect on output and cause inflation to rise in the short term. Our results also suggest that the effects on aggregate supply have grown stronger in recent decades.

  12. Shock absorbing structure

    Kojima, Naoki; Matsushita, Kazuo.

    1992-01-01

    Small pieces of shock absorbers are filled in a space of a shock absorbing vessel which is divided into a plurality of sections by partitioning members. These sections function to prevent excess deformation or replacement of the fillers upon occurrence of falling accident. Since the shock absorbing small pieces in the shock absorbing vessel are filled irregularly, shock absorbing characteristics such as compression strength is not varied depending on the direction, but they exhibit excellent shock absorbing performance. They surely absorb shocks exerted on a transportation vessel upon falling or the like. If existing artificial fillers such as pole rings made of metal or ceramic and cut pieces such as alumium extrusion molding products are used as the shock absorbing pieces, they have excellent fire-proofness and cold resistance since the small pieces are inflammable and do not contain water. (T.M.)

  13. Melting under shock compression

    Bennett, B.I.

    1980-10-01

    A simple model, using experimentally measured shock and particle velocities, is applied to the Lindemann melting formula to predict the density, temperature, and pressure at which a material will melt when shocked from room temperature and zero pressure initial conditions

  14. Evoked Brain Activity and Personnel Performance

    1987-10-01

    Shucard and Horn (1972), Galbraith, Gliddon, and Busk (1970), and Callaway (1975), the latter using Navy recruits. Callaway’s own work was reported at...G.C., Gliddon, J.B., & Busk , J. (1970). Visual evoked responses in mentally retarded and nonretarded subjects. American Journal of Mental Deficiency

  15. Is Urgent Evoke a Digital Ba?

    Wichmand, Mette

    2018-01-01

    of such a platform, the World Bank’s online game Urgent Evoke, which has been designed with the pur- pose of engaging citizens in developing innovative solutions for sociopolitical problems like poverty. The analysis is based on Nonaka’s concept of Ba, which means “place” and is described as a platform for advancing...

  16. Auditory and visual evoked potentials during hyperoxia

    Smith, D. B. D.; Strawbridge, P. J.

    1974-01-01

    Experimental study of the auditory and visual averaged evoked potentials (AEPs) recorded during hyperoxia, and investigation of the effect of hyperoxia on the so-called contingent negative variation (CNV). No effect of hyperoxia was found on the auditory AEP, the visual AEP, or the CNV. Comparisons with previous studies are discussed.

  17. Interhemispheric Asymmetries in Visual Evoked Potential Amplitude

    1980-06-12

    Layne, 1965) and of patients with Korsakoff’s syndrome (Malerstein and Callaway, 1969) . In the schizophrenics, the high variability is related to poor...communication. Malerstein, A. J., Callaway, E. Two-tone average evoked response in Korsakoff patients. J. Psychiatr. Res. 6: 253-260, 1969. Marsh, G

  18. Biomass shock pretreatment

    Holtzapple, Mark T.; Madison, Maxine Jones; Ramirez, Rocio Sierra; Deimund, Mark A.; Falls, Matthew; Dunkelman, John J.

    2014-07-01

    Methods and apparatus for treating biomass that may include introducing a biomass to a chamber; exposing the biomass in the chamber to a shock event to produce a shocked biomass; and transferring the shocked biomass from the chamber. In some aspects, the method may include pretreating the biomass with a chemical before introducing the biomass to the chamber and/or after transferring shocked biomass from the chamber.

  19. Relativistic Shock Acceleration

    Duffy, P.; Downes, T.P.; Gallant, Y.A.; Kirk, J.G.

    1999-01-01

    In this paper we briefly review the basic theory of shock waves in relativistic hydrodynamics and magneto-hydrodynamics, emphasising some astrophysically interesting cases. We then present an overview of the theory of particle acceleration at such shocks describing the methods used to calculate the spectral indices of energetic particles. Recent results on acceleration at ultra-relativistic shocks are discussed. (author)

  20. Normalization of auditory evoked potential and visual evoked potential in patients with idiot savant.

    Chen, X; Zhang, M; Wang, J; Lou, F; Liang, J

    1999-03-01

    To investigate the variations of auditory evoked potentials (AEP) and visual evoked potentials (VEP) of patients with idiot savant (IS) syndrome. Both AEP and VEP were recorded from 7 patients with IS syndrome, 21 mentally retarded (MR) children without the syndrome and 21 normally age-matched controls, using a Dantec concerto SEEG-16 BEAM instrument. Both AEP and VEP of MR group showed significantly longer latencies (P1 and P2 latencies of AEP, P savant syndrome presented normalized AEP and VEP.

  1. Genetic influence demonstrated for MEG-recorded somatosensory evoked responses

    van 't Ent, D.; van Soelen, I.L.C.; Stam, K.J.; de Geus, E.J.C.; Boomsma, D.I.

    2010-01-01

    We tested for a genetic influence on magnetoencephalogram (MEG)-recorded somatosensory evoked fields (SEFs) in 20 monozygotic (MZ) and 14 dizygotic (DZ) twin pairs. Previous electroencephalogram (EEG) studies that demonstrated a genetic contribution to evoked responses generally focused on

  2. Visually Evoked Spiking Evolves While Spontaneous Ongoing Dynamics Persist

    Huys, Raoul; Jirsa, Viktor K; Darokhan, Ziauddin

    2016-01-01

    attractor. Its existence guarantees that evoked spiking return to the spontaneous state. However, the spontaneous ongoing spiking state and the visual evoked spiking states are qualitatively different and are separated by a threshold (separatrix). The functional advantage of this organization...

  3. Alfven shock trains

    Malkov, M.A.; Kennel, C.F.; Wu, C.C.; Pellat, R.; Shapiro, V.D.

    1991-01-01

    The Cohen--Kulsrud--Burgers equation (CKB) is used to consider the nonlinear evolution of resistive, quasiparallel Alfven waves subject to a long-wavelength, plane-polarized, monochromatic instability. The instability saturates by nonlinear steepening, which proceeds until the periodic waveform develops an interior scale length comparable to the dissipation length; a fast or an intermediate shock then forms. The result is a periodic train of Alfven shocks of one or the other type. For propagation strictly parallel to the magnetic field, there will be two shocks per instability wavelength. Numerical integration of the time-dependent CKB equation shows that an initial, small-amplitude growing wave asymptotes to a stable, periodic stationary wave whose analytic solution specifies how the type of shock embedded in the shock train, and the amplitude and speed of the shock train, depend on the strength and phase of the instability. Waveforms observed upstream of the Earth's bowshock and cometary shocks resemble those calculated here

  4. Thought-evoking approaches in engineering problems

    2014-01-01

    In creating the value-added product in not distant future, it is necessary and inevitable to establish a holistic and though-evoking approach to the engineering problem, which should be at least associated with the inter-disciplinary knowledge and thought processes across the whole engineering spheres. It is furthermore desirable to integrate it with trans-disciplinary aspects ranging from manufacturing culture, through liberal-arts engineering, and industrial sociology.   The thought-evoking approach can be exemplified and typified by representative engineering problems: unveiling essential features in ‘Tangential Force Ratio and Interface Pressure’, prototype development for ‘Bio-mimetic Needle’ and application of ‘Water-jet Machining to Artificial Hip Joint’, product innovation in ‘Heat Sink for Computer’, application of ‘Graph Theory’ to similarity evaluation of production systems, leverage among reciprocity attributes in ‘Industrial and Engineering Designs for Machine Enclosure’,...

  5. System Shock: The Archetype of Operational Shock

    2017-05-25

    the battle space. They can also facilitate a much greater understanding of the variables involved in each party’s decision - making process. However...system shock nests within current US Army Unified Land Operations doctrine. In order to test the utility of system shock theory to Gray Zone...23 Neil E. Harrison, “Thinking about the World We Make ” in Chaos Theory in the Social Sciences: Foundations and Applications

  6. Associative learning in humans--conditioning of sensory-evoked brain activity.

    Skrandies, W; Jedynak, A

    2000-01-01

    A classical conditioning paradigm was employed in two experiments performed on 35 human volunteers. In nine subjects, the presentation of Landolt rings (conditioned stimuli, CS + ) was paired with an electric stimulus (unconditioned stimuli, UCS) applied to the left median nerve. Neutral visual control stimuli were full circles (CS -) that were not paired with the UCS. The skin conductance response (SCR) was determined in a time interval of 5 s after onset of the visual stimuli, and it was measured in the acquisition and test phase. Associative learning was reflected by a SCR occurring selectively with CS +. The same experiment was repeated with another group of 26 adults while electroencephalogram (EEG) was recorded from 30 electrodes. For each subject, mean evoked potentials were computed. In 13 of the subjects, a conditioning paradigm was followed while the other subjects served as the control group (non-contingent stimulation). There were somatosensory and visual brain activity evoked by the stimuli. Conditioned components were identified by computing cross-correlation between evoked somatosensory components and the averaged EEG. In the visual evoked brain activity, three components with mean latencies of 105.4, 183.2, and 360.3 ms were analyzed. Somatosensory stimuli were followed by major components that occurred at mean latencies of 48.8, 132.5, 219.7, 294.8, and 374.2 ms latency after the shock. All components were analyzed in terms of latency, field strength, and topographic characteristics, and were compared between groups and experimental conditions. Both visual and somatosensory brain activity was significantly affected by classical conditioning. Our data illustrate how associative learning affects the topography of brain electrical activity elicited by presentation of conditioned visual stimuli.

  7. Music-Evoked Emotions—Current Studies

    Schaefer, Hans-Eckhardt

    2017-01-01

    The present study is focused on a review of the current state of investigating music-evoked emotions experimentally, theoretically and with respect to their therapeutic potentials. After a concise historical overview and a schematic of the hearing mechanisms, experimental studies on music listeners and on music performers are discussed, starting with the presentation of characteristic musical stimuli and the basic features of tomographic imaging of emotional activation in the brain, such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), which offer high spatial resolution in the millimeter range. The progress in correlating activation imaging in the brain to the psychological understanding of music-evoked emotion is demonstrated and some prospects for future research are outlined. Research in psychoneuroendocrinology and molecular markers is reviewed in the context of music-evoked emotions and the results indicate that the research in this area should be intensified. An assessment of studies involving measuring techniques with high temporal resolution down to the 10 ms range, as, e.g., electroencephalography (EEG), event-related brain potentials (ERP), magnetoencephalography (MEG), skin conductance response (SCR), finger temperature, and goose bump development (piloerection) can yield information on the dynamics and kinetics of emotion. Genetic investigations reviewed suggest the heredity transmission of a predilection for music. Theoretical approaches to musical emotion are directed to a unified model for experimental neurological evidence and aesthetic judgment. Finally, the reports on musical therapy are briefly outlined. The study concludes with an outlook on emerging technologies and future research fields. PMID:29225563

  8. Do ambient urban odors evoke basic emotions?

    Sandra Theresia Weber-Glass

    2014-04-01

    Full Text Available Fragrances, such as plant odors, have been shown to evoke autonomic response patterns associated with Ekman’s (Ekman et al., 1983 basic emotions happiness, surprise, anger, fear, sadness and disgust. Inducing positive emotions by odors in highly frequented public spaces could serve to improve the quality of life in urban environments. Thus, the present study evaluated the potency of ambient odors connoted with an urban environment to evoke basic emotions on an autonomic and cognitive response level. Synthetic mixtures representing the odors of disinfectant, candles / bees wax, summer air, burnt smell, vomit and musty smell as well as odorless water as a control were presented five times in random order to 30 healthy, non-smoking human subjects with intact sense of smell. Skin temperature, skin conductance, breathing rate, forearm muscle activity, blink rate and heart rate were recorded simultaneously. Subjects rated the odors in terms of pleasantness, intensity and familiarity and gave verbal labels to each odor as well as cognitive associations with the basic emotions. The results showed that the amplitude of the skin conductance response varied as a function of odor presentation. Burnt smell and vomit elicited significantly higher electrodermal responses than summer air. Also, a negative correlation was revealed between the amplitude of the skin conductance response and hedonic odor valence indicating that the magnitude of the electrodermal response increased with odor unpleasantness. The analysis of the cognitive associations between odors and basic emotions showed that candles / bees wax and summer air were specifically associated with happiness whereas burnt smell and vomit were uniquely associated with disgust. Our findings suggest that city odors may evoke specific cognitive associations of basic emotions and that autonomic activity elicited by such odors is related to odor hedonics.

  9. Hydraulic shock absorbers

    Thatcher, G.; Davidson, D. F.

    1984-01-01

    A hydraulic shock absorber of the dash pot kind for use with electrically conducting liquid such as sodium, has magnet means for electro magnetically braking a stream of liquid discharged from the cylinder. The shock absorber finds use in a liquid metal cooled nuclear reactor for arresting control rods

  10. Our Favorite Film Shocks

    Willerslev, Rane; Suhr, Christian

    2014-01-01

    The modern medium of film has long been hailed for its capacity for producing shocks of an entertaining, thought-provoking, or even politically emancipative nature. But what is a shock, how and when does it occur, how long does it last, and are there particular techniques for producing cinematic...

  11. Climate shocks and conflict

    Papaioannou, Kostadis J.

    2016-01-01

    This paper offers a historical micro-level analysis of the impact of climate shocks on the incidence of civil conflict in colonial Nigeria (1912-1945). Primary historical sources on court cases, prisoners and homicides are used to capture conflict. To measure climate shocks we use the deviation

  12. Speech Evoked Auditory Brainstem Response in Stuttering

    Ali Akbar Tahaei

    2014-01-01

    Full Text Available Auditory processing deficits have been hypothesized as an underlying mechanism for stuttering. Previous studies have demonstrated abnormal responses in subjects with persistent developmental stuttering (PDS at the higher level of the central auditory system using speech stimuli. Recently, the potential usefulness of speech evoked auditory brainstem responses in central auditory processing disorders has been emphasized. The current study used the speech evoked ABR to investigate the hypothesis that subjects with PDS have specific auditory perceptual dysfunction. Objectives. To determine whether brainstem responses to speech stimuli differ between PDS subjects and normal fluent speakers. Methods. Twenty-five subjects with PDS participated in this study. The speech-ABRs were elicited by the 5-formant synthesized syllable/da/, with duration of 40 ms. Results. There were significant group differences for the onset and offset transient peaks. Subjects with PDS had longer latencies for the onset and offset peaks relative to the control group. Conclusions. Subjects with PDS showed a deficient neural timing in the early stages of the auditory pathway consistent with temporal processing deficits and their abnormal timing may underlie to their disfluency.

  13. Interaural difference values of vestibular evoked myogenic.

    Marziyeh Moallemi

    2015-01-01

    Full Text Available Migraine is a neurologic disease, which often is associated with a unilateral headache. Vestibular abnormalities are common in migraine. Vestibular evoked myogenic potentials (VEMPs assess otolith function in particular functional integrity of the saccule and the inferior vestibular nerve. We used VEMP to evaluate if the migraine headache can affect VEMP asymmetry parameters. A total of 25 patients with migraine (22 females and 3 males who were diagnosed according to the criteria of IHS-1988 were enrolled in this cross-sectional study. Control group consisted of 26 healthy participants (18 female and 8 male, without neurotological symptoms and history of migraine. The short tone burst (95 dB nHL, 500 Hz was presented to ears. VEMP was recorded with surface electromyography over the contracted ipsilateral sternocleidomastoid (SCM muscle. Although current results showed that the amplitude ratio is greater in migraine patients than normal group, there was no statistical difference between two groups in mean asymmetry parameters of VEMP. Asymmetry measurements in vestibular evoked myogenic potentials probably are not indicators of unilateral deficient in saccular pathways of migraine patients.

  14. Laser-evoked coloration in polymers

    Zheng, H.Y.; Rosseinsky, David; Lim, G.C.

    2005-01-01

    Laser-evoked coloration in polymers has long been a major aim of polymer technology for potential applications in product surface decoration, marking personalised images and logos. However, the coloration results reported so far were mostly attributed to laser-induced thermal-chemical reactions. The laser-irradiated areas are characterized with grooves due to material removal. Furthermore, only single color was laser-induced in any given polymer matrix. To induce multiple colors in a given polymer matrix with no apparent surface material removal is most desirable and challenging and may be achieved through laser-induced photo-chemical reactions. However, little public information is available at present. We report that two colors of red and green have been produced on an initially transparent CPV/PVA samples through UV laser-induced photo-chemical reactions. This is believed the first observation of laser-induced multiple-colors in the given polymer matrix. It is believed that the colorants underwent photo-effected electron transfer with suitable electron donors from the polymers to change from colorless bipyridilium Bipm 2+ to the colored Bipm + species. The discovery may lead to new approaches to the development of laser-evoked multiple coloration in polymers

  15. Brainstem auditory evoked potentials in horses

    Juliana Almeida Nogueira da Gama

    2016-04-01

    Full Text Available ABSTRACT: The brainstem auditory evoked potential (BAEP evaluates the integrity of the auditory pathways to the brainstem. The aim of this study was to evoke BAEPs in 21 clinically normal horses. The animals were sedated with detomidine hydrochloride (0.013mg.kg-1 BW. Earphones were inserted and rarefaction clicks at 90 dB and noise masking at 40 dB were used. After performing the test, the latencies of waves (I, II, III, IV, and V and interpeaks(I-III, III-V, and I-V were identified. The mean latencies of the waves were as follows: wave I, 2.4 ms; wave II, 2.24 ms; wave III, 3.61ms; wave IV, 4.61ms; and wave V, 5.49ms. The mean latencies of the interpeaks were as follows: I-III, 1.37ms; III-V, 1.88ms; and I-V, 3.26ms. This is the first study using BAEPs in horses in Brazil, and the observed latencies will be used as normative data for the interpretation of tests performed on horses with changes related to auditory system or neurologic abnormalities.

  16. Pattern visual evoked potentials in malingering.

    Nakamura, A; Akio, T; Matsuda, E; Wakami, Y

    2001-03-01

    We previously developed a new method for estimating objective visual acuity by means of pattern visual evoked potentials (PVEP). In this study, this method was applied to the diagnosis of malingering. Six patients ranging in age from 40 to 54 years (mean 47 years) with suspected malingering were evaluated by means of the visual evoked potential test, optokinetic nystagmus (OKN) inhibition test, and the visual field test. In the PVEP study, the stimulus consisted of black and white checkerboards (39', 26', 15', and 9') with a visual angle of 8 degrees, contrast level of 15%, and a frequency of 0.7 Hz. One hundred PVEP responses were averaged per session. Routine ophthalmic examinations were normal in all patients. Five patients had a tubularly constricted visual field, and the remaining patient had a normal visual field. The objective visual acuities of the six patients estimated from PVEP were better than their subjective visual acuities estimated with Landolt rings. Among a variety of psychophysical and electrophysiologic ancillary tests, we consider our PVEP method a useful method for objectively determining visual acuity in a patient with signs of ocular malingering.

  17. Evoked potentials in pediatric cerebral malaria

    Minal Bhanushali

    2011-12-01

    Full Text Available Cortical evoked potentials (EP provide localized data regarding brain function and may offer prognostic information and insights into the pathologic mechanisms of malariamediated cerebral injury. As part of a prospective cohort study, we obtained somatosensory evoked potentials (SSEPs and brainstem auditory EPs (AEPs within 24 hours of admission on 27 consecutive children admitted with cerebral malaria (CM. Children underwent follow-up for 12 months to determine if they had any long term neurologic sequelae. EPs were obtained in 27 pediatric CM admissions. Two children died. Among survivors followed an average of 514 days, 7/25 (28.0% had at least one adverse neurologic outcome. Only a single subject had absent cortical EPs on admission and this child had a good neurologic outcome. Among pediatric CM survivors, cortical EPs are generally intact and do not predict adverse neurologic outcomes. Further study is needed to determine if alterations in cortical EPs can be used to predict a fatal outcome in CM.

  18. Music-evoked emotions in schizophrenia.

    Abe, Daijyu; Arai, Makoto; Itokawa, Masanari

    2017-07-01

    Previous studies have reported that people with schizophrenia have impaired musical abilities. Here we developed a simple music-based assay to assess patient's ability to associate a minor chord with sadness. We further characterize correlations between impaired musical responses and psychiatric symptoms. We exposed participants sequentially to two sets of sound stimuli, first a C-major progression and chord, and second a C-minor progression and chord. Participants were asked which stimulus they associated with sadness, the first set, the second set, or neither. The severity of psychiatric symptoms was assessed using the Positive and Negative Syndrome Scale (PANSS). Study participants were 29 patients diagnosed with schizophrenia and 29 healthy volunteers matched in age, gender and musical background. 37.9% (95% confidence interval [CI]:19.1-56.7) of patients with schizophrenia associated the minor chord set as sad, compared with 97.9% (95%CI: 89.5-103.6) of controls. Four patients were diagnosed with treatment-resistant schizophrenia, and all four failed to associate the minor chord with sadness. Patients who did not recognize minor chords as sad had significantly higher scores on all PANSS subscales. A simple test allows music-evoked emotions to be assessed in schizophrenia patient, and may show potential relationships between music-evoked emotions and psychiatric symptoms. Copyright © 2016. Published by Elsevier B.V.

  19. Collisionless shock waves

    Sagdeev, R.Z.; Kennel, C.F.

    1991-01-01

    Collisionless shocks cannot occur naturally on the earth, because nearly all matter here consists of electrically neutral atoms and molecules. In space, however, high temperatures and ultraviolet radiation from hot stars decompose atoms into their constituent nuclei and electrons, producing a soup of electrically charged particles known as a plasma. Plasma physicists proposed that the collective electrical and magnetic properties of plasmas could produce interactions that take the place of collisions and permit shocks to form. In 1964 the theoretical work found its first experimental confirmation. Norman F. Ness and his colleagues at the Goddard Space Flight Center, using data collected from the iMP-1 spacecraft, detected clear signs that a collisionless shock exists where the solar wind encounters the earth's magnetic field. More recent research has demonstrated that collisionless shocks appear in a dazzling array of astronomical settings. For example, shocks have been found in the solar wind upstream (sunward) of all the planet and comets that have been visited by spacecraft. Violent flares on the sun generate shocks that propagate to the far reaches of the solar system; tremendous galactic outbursts create disruptions in the intergalactic medium that are trillions of times larger. In addition, many astrophysicists think that shocks from supernova explosions in our galaxy accelerate cosmic rays, a class of extraordinarily energetic elementary particles and atomic nuclei that rain down on the earth from all directions

  20. Pediatric Toxic Shock Syndrome

    Jennifer Yee

    2017-09-01

    Full Text Available Audience: This scenario was developed to educate emergency medicine residents on the diagnosis and management of a pediatric patient with toxic shock syndrome. The case is also appropriate for teaching of medical students and advanced practice providers, as well as a review of the principles of crisis resource management, teamwork, and communication. Introduction: Toxic shock syndrome is a low-frequency, high-acuity scenario requiring timely identification and aggressive management. If patients suffering from this condition are managed incorrectly, they may progress into multi-organ dysfunction and potentially death. Toxic shock syndrome has been associated with Streptococcus and Staphylococcus aureus (Staph. Approximately half of Staph cases are associated with menstruation, which was first described in the 1970s-1980s and was associated with the use of absorbent tampons.1 Group A Streptococcus may cause complications such as necrotizing fasciitis and gangrenous myositis.2 Pediatric patients may present critically ill from toxic shock syndrome. Providers need to perform a thorough history and physical exam to discern the source of infection. Management requires aggressive care with antibiotics and IV fluids. Objectives: By the end of this simulation session, the learner will be able to: 1 Recognize toxic shock syndrome. 2 Review the importance of a thorough physical exam. 3 Discuss management of toxic shock syndrome, including supportive care and the difference in antibiotic choices for streptococcal and staphylococcal toxic shock syndrome. 4 Appropriately disposition a patient suffering from toxic shock syndrome. 5 Communicate effectively with team members and nursing staff during a resuscitation of a critically ill patient. Method: This session was conducted using high-fidelity simulation, followed by a debriefing session and lecture on toxic shock syndrome.

  1. Shocks near Jamming

    Gómez, Leopoldo R.; Turner, Ari M.; van Hecke, Martin; Vitelli, Vincenzo

    2012-02-01

    Nonlinear sound is an extreme phenomenon typically observed in solids after violent explosions. But granular media are different. Right when they jam, these fragile and disordered solids exhibit a vanishing rigidity and sound speed, so that even tiny mechanical perturbations form supersonic shocks. Here, we perform simulations in which two-dimensional jammed granular packings are dynamically compressed and demonstrate that the elementary excitations are strongly nonlinear shocks, rather than ordinary phonons. We capture the full dependence of the shock speed on pressure and impact intensity by a surprisingly simple analytical model.

  2. Mechanical shock absorber

    Vrillon, Bernard.

    1973-01-01

    The mechanical shock absorber described is made of a constant thickness plate pierced with circular holes regularly distributed in such a manner that for all the directions along which the strain is applied during the shock, the same section of the substance forming the plate is achieved. The shock absorber is made in a metal standing up to extensive deformation before breaking, selected from a group comprising mild steels and austenitic stainless steels. This apparatus is used for handling pots of fast neutron reactor fuel elements [fr

  3. Shock formation of HCO+

    Elitzur, M.

    1983-01-01

    It is shown that shocks propagating in dense molecular regions will lead to a decrease in HCO + relative abundance, in agreement with previous results by Iglesias and Silk. The shock enhancement of HCO + detected in the supernova remnant IC 443 by Dickenson et al. is due to enhanced ionization in the shocked material. This is the result of the material penetrating the remnant cavity where it becomes exposed to the trapped cosmic rays. A similar enhancement appears to have been detected by Wootten in W28 and is explained by the same model

  4. Shock Isolation Elements Testing for High Input Loadings. Volume II. Foam Shock Isolation Elements.

    SHOCK ABSORBERS ), (*GUIDED MISSILE SILOS, SHOCK ABSORBERS ), (*EXPANDED PLASTICS, (*SHOCK(MECHANICS), REDUCTION), TEST METHODS, SHOCK WAVES, STRAIN(MECHANICS), LOADS(FORCES), MATHEMATICAL MODELS, NUCLEAR EXPLOSIONS, HARDENING.

  5. Music evokes vicarious emotions in listeners.

    Kawakami, Ai; Furukawa, Kiyoshi; Okanoya, Kazuo

    2014-01-01

    Why do we listen to sad music? We seek to answer this question using a psychological approach. It is possible to distinguish perceived emotions from those that are experienced. Therefore, we hypothesized that, although sad music is perceived as sad, listeners actually feel (experience) pleasant emotions concurrent with sadness. This hypothesis was supported, which led us to question whether sadness in the context of art is truly an unpleasant emotion. While experiencing sadness may be unpleasant, it may also be somewhat pleasant when experienced in the context of art, for example, when listening to sad music. We consider musically evoked emotion vicarious, as we are not threatened when we experience it, in the way that we can be during the course of experiencing emotion in daily life. When we listen to sad music, we experience vicarious sadness. In this review, we propose two sides to sadness by suggesting vicarious emotion.

  6. Counseling For Future Shock

    Morgan, Lewis B.

    1974-01-01

    In this article the author looks at some of the searing prophecies made by Alvin Toffler in his book Future Shock and relates them to the world of the professional counselor and the clientele the counselor attempts to serve. (Author)

  7. Life shocks and homelessness.

    Curtis, Marah A; Corman, Hope; Noonan, Kelly; Reichman, Nancy E

    2013-12-01

    We exploited an exogenous health shock-namely, the birth of a child with a severe health condition-to investigate the effect of a life shock on homelessness in large cities in the United States as well as the interactive effects of the shock with housing market characteristics. We considered a traditional measure of homelessness, two measures of housing instability thought to be precursors to homelessness, and a combined measure that approximates the broadened conceptualization of homelessness under the 2009 Homeless Emergency Assistance and Rapid Transition to Housing Act (2010). We found that the shock substantially increases the likelihood of family homelessness, particularly in cities with high housing costs. The findings are consistent with the economic theory of homelessness, which posits that homelessness results from a conjunction of adverse circumstances in which housing markets and individual characteristics collide.

  8. Unlimited Relativistic Shock Surfing Acceleration

    Ucer, D.; Shapiro, V. D.

    2001-01-01

    Nonrelativistic shock surfing acceleration at quasiperpendicular shocks is usually considered to be a preacceleration mechanism for slow pickup ions to initiate diffusive shock acceleration. In shock surfing, the particle accelerates along the shock front under the action of the convective electric field of the plasma flow. However, the particle also gains kinetic energy normal to the shock and eventually escapes downstream. We consider the case when ions are accelerated to relativistic velocities. In this case, the ions are likely to be trapped for infinitely long times, because the energy of bounce oscillations tends to decrease during acceleration. This suggests the possibility of unlimited acceleration by shock surfing

  9. Technology shocks matter

    Jonas D. M. Fisher

    2002-01-01

    This paper uses the neoclassical growth model to identify the effects of technological change on the US business cycle. In the model there are two sources of technological change: neutral, which effects the production of all goods homogeneously, and investment-specific. Investment-specific shocks are the unique source of the secular trend in the real price of investment goods, while shocks to both kinds of technology are the only factors which affect labor productivity in the long run. Consis...

  10. The Heliospheric Termination Shock

    Jokipii, J. R.

    2013-06-01

    The heliospheric termination shock is a vast, spheroidal shock wave marking the transition from the supersonic solar wind to the slower flow in the heliosheath, in response to the pressure of the interstellar medium. It is one of the most-important boundaries in the outer heliosphere. It affects energetic particles strongly and for this reason is a significant factor in the effects of the Sun on Galactic cosmic rays. This paper summarizes the general properties and overall large-scale structure and motions of the termination shock. Observations over the past several years, both in situ and remote, have dramatically revised our understanding of the shock. The consensus now is that the shock is quite blunt, is with the front, blunt side canted at an angle to the flow direction of the local interstellar plasma relative to the Sun, and is dynamical and turbulent. Much of this new understanding has come from remote observations of energetic charged particles interacting with the shock, radio waves and radiation backscattered from interstellar neutral atoms. The observations and the implications are discussed.

  11. Shocks in fragile matter

    Vitelli, Vincenzo

    2012-02-01

    Non-linear sound is an extreme phenomenon typically observed in solids after violent explosions. But granular media are different. Right when they unjam, these fragile and disordered solids exhibit vanishing elastic moduli and sound speed, so that even tiny mechanical perturbations form supersonic shocks. Here, we perform simulations in which two-dimensional jammed granular packings are continuously compressed, and demonstrate that the resulting excitations are strongly nonlinear shocks, rather than linear waves. We capture the full dependence of the shock speed on pressure and compression speed by a surprisingly simple analytical model. We also treat shear shocks within a simplified viscoelastic model of nearly-isostatic random networks comprised of harmonic springs. In this case, anharmonicity does not originate locally from nonlinear interactions between particles, as in granular media; instead, it emerges from the global architecture of the network. As a result, the diverging width of the shear shocks bears a nonlinear signature of the diverging isostatic length associated with the loss of rigidity in these floppy networks.

  12. Psychological and physiological responses to odor-evoked autobiographic memory.

    Matsunaga, Masahiro; Isowa, Tokiko; Yamakawa, Kaori; Kawanishi, Yoko; Tsuboi, Hirohito; Kaneko, Hiroshi; Sadato, Norihiro; Oshida, Akiko; Katayama, Atsushi; Kashiwagi, Mitsuyoshi; Ohira, Hideki

    2011-01-01

    The "Proust phenomenon" occurs when a certain smell evokes a specific memory. Recent studies have demonstrated that odor-evoked autobiographic memories are more emotional than those elicited by other sensory stimuli because of the direct neural communication between the olfactory system and the amygdala. The amygdala is known to regulate various physiological activities including the endocrine and immune systems; therefore, odor-evoked autobiographic memory may trigger various psychological and physiological responses; however, the responses elicited by this memory remains obscure. In this study, we aimed to investigate the psychological and physiological responses accompanying odor-evoked autobiographic memory. We recruited healthy male and female volunteers and investigated changes in their mood states and autonomic nervous, endocrine, and immune activities when autobiographic memory was evoked in the participants by asking them to smell an odor(s) that was nostalgic to them. The autobiographic memories associated with positive emotion resulted in increased positive mood states, such as comfort and happiness, and decreased negative mood states, such as anxiety. Furthermore, heart rate was decreased, skin-conductance level was increased, and peripheral interleukin-2 level was decreased after smelling the nostalgic odor. These psychological and physiological responses were significantly correlated. The present study suggests that odor-evoked autobiographic memory along with a positive feeling induce various physiological responses, including the autonomic nervous and immune activities. To the best of our knowledge, the present study is the first to observe an interaction between odor-evoked autobiographic memories and immune function.

  13. Visually Evoked Spiking Evolves While Spontaneous Ongoing Dynamics Persist

    Huys, Raoul; Jirsa, Viktor K.; Darokhan, Ziauddin; Valentiniene, Sonata; Roland, Per E.

    2016-01-01

    Neurons in the primary visual cortex spontaneously spike even when there are no visual stimuli. It is unknown whether the spiking evoked by visual stimuli is just a modification of the spontaneous ongoing cortical spiking dynamics or whether the spontaneous spiking state disappears and is replaced by evoked spiking. This study of laminar recordings of spontaneous spiking and visually evoked spiking of neurons in the ferret primary visual cortex shows that the spiking dynamics does not change: the spontaneous spiking as well as evoked spiking is controlled by a stable and persisting fixed point attractor. Its existence guarantees that evoked spiking return to the spontaneous state. However, the spontaneous ongoing spiking state and the visual evoked spiking states are qualitatively different and are separated by a threshold (separatrix). The functional advantage of this organization is that it avoids the need for a system reorganization following visual stimulation, and impedes the transition of spontaneous spiking to evoked spiking and the propagation of spontaneous spiking from layer 4 to layers 2–3. PMID:26778982

  14. Auditory evoked potential measurements in elasmobranchs

    Casper, Brandon; Mann, David

    2005-04-01

    Auditory evoked potentials (AEP) were first used to examine hearing in elasmobranchs by Corwin and Bullock in the late 1970s and early 1980s, marking the first time AEPs had been measured in fishes. Results of these experiments identified the regions of the ear and brain in which sound is processed, though no actual hearing thresholds were measured. Those initial experiments provided the ground work for future AEP experiments to measure fish hearing abilities in a manner that is much faster and more convenient than classical conditioning. Data will be presented on recent experiments in which AEPs were used to measure the hearing thresholds of two species of elasmobranchs: the nurse shark, Ginglymostoma cirratum, and the yellow stingray, Urobatis jamaicencis. Audiograms were analyzed and compared to previously published audiograms obtained using classical conditioning with results indicating that hearing thresholds were similar for the two methods. These data suggest that AEP testing is a viable option when measuring hearing in elasmobranchs and can increase the speed in which future hearing measurements can be obtained.

  15. Transient evoked otoacoustic emissions in rock musicians.

    Høydal, Erik Harry; Lein Størmer, Carl Christian; Laukli, Einar; Stenklev, Niels Christian

    2017-09-01

    Our focus in this study was the assessment of transient evoked otoacoustic emissions (TEOAEs) in a large group of rock musicians. A further objective was to analyse tinnitus among rock musicians as related to TEOAEs. The study was a cross-sectional survey of rock musicians selected at random. A control group was included at random for comparison. We recruited 111 musicians and a control group of 40 non-musicians. Testing was conducted by using clinical examination, pure tone audiometry, TEOAEs and a questionnaire. TEOAE SNR in the half-octave frequency band centred on 4 kHz was significantly lower bilaterally in musicians than controls. This effect was strongly predicted by age and pure-tone hearing threshold levels in the 3-6 kHz range. Bilateral hearing thresholds were significantly higher at 6 kHz in musicians. Twenty percent of the musicians had permanent tinnitus. There was no association between the TEOAE parameters and permanent tinnitus. Our results suggest an incipient hearing loss at 6 kHz in rock musicians. Loss of TEOAE SNR in the 4 kHz half-octave frequency band was observed, but it was related to higher mean 3-6 kHz hearing thresholds and age. A large proportion of rock musicians have permanent tinnitus.

  16. Deconvolution of the vestibular evoked myogenic potential.

    Lütkenhöner, Bernd; Basel, Türker

    2012-02-07

    The vestibular evoked myogenic potential (VEMP) and the associated variance modulation can be understood by a convolution model. Two functions of time are incorporated into the model: the motor unit action potential (MUAP) of an average motor unit, and the temporal modulation of the MUAP rate of all contributing motor units, briefly called rate modulation. The latter is the function of interest, whereas the MUAP acts as a filter that distorts the information contained in the measured data. Here, it is shown how to recover the rate modulation by undoing the filtering using a deconvolution approach. The key aspects of our deconvolution algorithm are as follows: (1) the rate modulation is described in terms of just a few parameters; (2) the MUAP is calculated by Wiener deconvolution of the VEMP with the rate modulation; (3) the model parameters are optimized using a figure-of-merit function where the most important term quantifies the difference between measured and model-predicted variance modulation. The effectiveness of the algorithm is demonstrated with simulated data. An analysis of real data confirms the view that there are basically two components, which roughly correspond to the waves p13-n23 and n34-p44 of the VEMP. The rate modulation corresponding to the first, inhibitory component is much stronger than that corresponding to the second, excitatory component. But the latter is more extended so that the two modulations have almost the same equivalent rectangular duration. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Surface electrical stimulation to evoke referred sensation.

    Forst, Johanna C; Blok, Derek C; Slopsema, Julia P; Boss, John M; Heyboer, Lane A; Tobias, Carson M; Polasek, Katharine H

    2015-01-01

    Surface electrical stimulation (SES) is being investigated as a noninvasive method to evoke natural sensations distal to electrode location. This may improve treatment for phantom limb pain as well as provide an alternative method to deliver sensory feedback. The median and/or ulnar nerves of 35 subjects were stimulated at the elbow using surface electrodes. Strength-duration curves of hand sensation were found for each subject. All subjects experienced sensation in their hand, which was mostly described as a paresthesia-like sensation. The rheobase and chronaxie values were found to be lower for the median nerve than the ulnar nerve, with no significant difference between sexes. Repeated sessions with the same subject resulted in sufficient variability to suggest that recalculating the strength-duration curve for each electrode placement is necessary. Most of the recruitment curves in this study were generated with 28 to 36 data points. To quickly reproduce these curves with limited increase in error, we recommend 10 data points. Future studies will focus on obtaining different sensations using SES with the strength-duration curve defining the threshold of the effective parameter space.

  18. Physics of Collisionless Shocks Space Plasma Shock Waves

    Balogh, André

    2013-01-01

    The present book provides a contemporary systematic treatment of shock waves in high-temperature collisionless plasmas as are encountered in near Earth space and in Astrophysics. It consists of two parts. Part I develops the complete theory of shocks in dilute hot plasmas under the assumption of absence of collisions among the charged particles when the interaction is mediated solely by the self-consistent electromagnetic fields. Such shocks are naturally magnetised implying that the magnetic field plays an important role in their evolution and dynamics. This part treats both subcritical shocks, which dissipate flow energy by generating anomalous resistance or viscosity, and supercritical shocks. The main emphasis is, however, on super-critical shocks where the anomalous dissipation is insufficient to retard the upstream flow. These shocks, depending on the direction of the upstream magnetic field, are distinguished as quasi-perpendicular and quasi-parallel shocks which exhibit different behaviours, reflecti...

  19. Life Shocks and Homelessness

    Corman, Hope; Noonan, Kelly; Reichman, Nancy E.

    2014-01-01

    We exploited an exogenous health shock—namely, the birth of a child with a severe health condition—to investigate the effect of a life shock on homelessness in large cities in the United States as well as the interactive effects of the shock with housing market characteristics. We considered a traditional measure of homelessness, two measures of housing instability thought to be precursors to homelessness, and a combined measure that approximates the broadened conceptualization of homelessness under the 2009 Homeless Emergency Assistance and Rapid Transition to Housing Act (2010). We found that the shock substantially increases the likelihood of family homelessness, particularly in cities with high housing costs. The findings are consistent with the economic theory of homelessness, which posits that homelessness results from a conjunction of adverse circumstances in which housing markets and individual characteristics collide. PMID:23868747

  20. Health Shocks and Retirement:

    Datta Gupta, Nabanita; Larsen, Mona

    We investigate the effect of an acute health shock on retirement among elderly male workers in Denmark, 1991-1999, and in particular whether various welfare state programs and institutions impinge on the retirement effect. The results show that an acute health event increases the retirement chances...... significant. For the most part, the retirement effect following a health shock seems to be immune to the availability of a multitude of government programs for older workers in Denmark....... benefits in Denmark nor by the promotion of corporate social responsibility initiatives since the mid-1990s. In the late 1990s, however, the retirement rate following a health shock is reduced to 3% with the introduction of the subsidized employment program (fleksjob) but this effect is not strongly...

  1. The Shock Routine

    van Hooren, Franca; Kaasch, Alexandra; Starke, Peter

    2014-01-01

    in Australia, Belgium, the Netherlands and Sweden over the course of four global economic shocks, we ask whether the notion of critical junctures is useful in understanding the nature of change triggered by crisis. The main empirical finding is that fundamental change in the aftermath of an exogenous shock...... is the exception rather than the rule. Instead, incremental ‘crisis routines’ based on existing policy instruments are overwhelmingly used to deal with economic hardship. We discuss these findings in the light of the psychological ‘threat-rigidity’ effect and reflect on their consequences for theories...

  2. Shock absorber in Ignalina NPP

    Bulavas, A.; Muralis, J.

    1996-09-01

    Theoretical calculation and experimental analysis of models of shock absorber in Ignalina NPP is presented. The results obtained from the investigation with model of shock absorber coincide with the theoretical calculation. (author). 2 figs., 3 refs

  3. Shock Response of Boron Carbide

    Dandekar, D. P. (Dattatraya Purushottam)

    2001-01-01

    .... The present work was undertaken to determine tensile/spall strength of boron carbide under plane shock wave loading and to analyze all available shock compression data on boron carbide materials...

  4. Fascinating World of Shock Waves

    Srimath

    travelling at supersonic speeds (more than the sound speed at ... actual earth- quake, travel at supersonic speeds. .... The time scale of the shock wave is also important ..... real lithotripsy where a shock wave is used shatter the kidney stones!

  5. [Maturation of cerebral somatosensory evoked potentials].

    Cadilhac, J; Zhu, Y; Georgesco, M; Echenne, B; Rodiere, M

    1985-07-01

    Cerebral somatosensory evoked potentials (SEPs) were elicited by stimulation of the median nerve and/or posterior tibial nerve in 117 children of 1 day to 16 years old. A major negative wave (N) was consistently recorded from the parietal region of the scalp when the arm was stimulated. The peak latency, the onset latency, the rising time and the duration of H wave are closely correlated with age and body length. The latencies are shortest in the subjects of 1-3 years old. SEPs to lower extremity stimulation were inconstant in the infants before the age of one. The major positive wave (P) has a variable topographic distribution along the middle line, over the scalp. The latencies are also very variable in the different subjects of the same age as well as in the same subject with different locations of active electrode. Among the parameters studied as for N wave, only the rising time of P wave is significantly correlated with age. The latencies of P wave have the shortest value in the subjects of 1-3 years old. The comparison of SEPs to upper and to lower limb stimulations shows that there is no relationship between them in respect to their morphology and amplitude. The minimum value of the latencies of N and P waves was observed at the same age but the difference between the peak latencies of P and N waves in the same subject increases considerably after 2 years of age and reaches the adult value after 5 years of age. These resultats indicate that the maturation of the peripheral somatosensory pathways proceeds at a higher rate than that of the central somatosensory pathways, that the maturation of the somatosensory pathways of the upper limb precedes that of the lower limb, and that the rising time of N or P waves is a good index of cortical maturation. The clinical utility of these SEPs in pediatrics is discussed.

  6. Pudendal somatosensory evoked potentials in normal women

    Geraldo A. Cavalcanti

    2007-12-01

    Full Text Available OBJECTIVE: Somatosensory evoked potential (SSEP is an electrophysiological test used to evaluate sensory innervations in peripheral and central neuropathies. Pudendal SSEP has been studied in dysfunctions related to the lower urinary tract and pelvic floor. Although some authors have already described technical details pertaining to the method, the standardization and the influence of physiological variables in normative values have not yet been established, especially for women. The aim of the study was to describe normal values of the pudendal SSEP and to compare technical details with those described by other authors. MATERIALS AND METHODS: The clitoral sensory threshold and pudendal SSEP latency was accomplished in 38 normal volunteers. The results obtained from stimulation performed on each side of the clitoris were compared to ages, body mass index (BMI and number of pregnancies. RESULTS: The values of clitoral sensory threshold and P1 latency with clitoral left stimulation were respectively, 3.64 ± 1.01 mA and 37.68 ± 2.60 ms. Results obtained with clitoral right stimulation were 3.84 ± 1.53 mA and 37.42 ± 3.12 ms, respectively. There were no correlations between clitoral sensory threshold and P1 latency with age, BMI or height of the volunteers. A significant difference was found in P1 latency between nulliparous women and volunteers who had been previously submitted to cesarean section. CONCLUSIONS: The SSEP latency represents an accessible and reproducible method to investigate the afferent pathways from the genitourinary tract. These results could be used as normative values in studies involving genitourinary neuropathies in order to better clarify voiding and sexual dysfunctions in females.

  7. Visual Evoked Response in Children Subjected to Prenatal Maternal ...

    neural conduction, or arousal level. S. Afr. Med. J., 48 ... pression treatment in either development or IQ, whether ... children in brain function at an electrophysiological level, ..... Perry, N. W. and Childers, D. G. (1969): The Human Visual Evoked.

  8. Brainstem Auditory Evoked Potential in HIV-Positive Adults.

    Matas, Carla Gentile; Samelli, Alessandra Giannella; Angrisani, Rosanna Giaffredo; Magliaro, Fernanda Cristina Leite; Segurado, Aluísio C

    2015-10-20

    To characterize the findings of brainstem auditory evoked potential in HIV-positive individuals exposed and not exposed to antiretroviral treatment. This research was a cross-sectional, observational, and descriptive study. Forty-five HIV-positive individuals (18 not exposed and 27 exposed to the antiretroviral treatment - research groups I and II, respectively - and 30 control group individuals) were assessed through brainstem auditory evoked potential. There were no significant between-group differences regarding wave latencies. A higher percentage of altered brainstem auditory evoked potential was observed in the HIV-positive groups when compared to the control group. The most common alteration was in the low brainstem. HIV-positive individuals have a higher percentage of altered brainstem auditory evoked potential that suggests central auditory pathway impairment when compared to HIV-negative individuals. There was no significant difference between individuals exposed and not exposed to antiretroviral treatment.

  9. Can visual evoked potentials be used in biometric identification?

    Power, Alan J; Lalor, Edmund C; Reilly, Richard B

    2006-01-01

    Due to known differences in the anatomical structure of the visual pathways and generators in different individuals, the use of visual evoked potentials offers the possibility of an alternative to existing biometrics methods. A study based on visual evoked potentials from 13 individuals was carried out to assess the best combination of temporal, spectral and AR modeling features to realize a robust biometric. From the results it can be concluded that visual evoked potentials show considerable biometric qualities, with classification accuracies reaching a high of 86.54% and that a specific temporal and spectral combination was found to be optimal. Based on these results the visual evoked potential may be a useful tool in biometric identification when used in conjunction with more established biometric methods.

  10. Methodologic aspects of acetylcholine-evoked relaxation of rabbit aorta

    Larsen, Kirsten Vendelbo; Nedergaard, Ove A.

    1999-01-01

    The acetylcholine-evoked relaxation of rabbit isolated thoracic aorta precontracted by phenylephrine was studied. Phenylephrine caused a steady contraction that was maintained for 6 h. In the presence of calcium disodium ethylenediaminetetraacetate (EDTA) and ascorbic acid the contraction decreased...

  11. Towards a neural basis of music-evoked emotions.

    Koelsch, Stefan

    2010-03-01

    Music is capable of evoking exceptionally strong emotions and of reliably affecting the mood of individuals. Functional neuroimaging and lesion studies show that music-evoked emotions can modulate activity in virtually all limbic and paralimbic brain structures. These structures are crucially involved in the initiation, generation, detection, maintenance, regulation and termination of emotions that have survival value for the individual and the species. Therefore, at least some music-evoked emotions involve the very core of evolutionarily adaptive neuroaffective mechanisms. Because dysfunctions in these structures are related to emotional disorders, a better understanding of music-evoked emotions and their neural correlates can lead to a more systematic and effective use of music in therapy. Copyright 2010 Elsevier Ltd. All rights reserved.

  12. INTERFERENCE OF UNIDIRECTIONAL SHOCK WAVES

    P. V. Bulat

    2015-05-01

    Full Text Available Subject of study.We consider interference of unidirectional shock waves or, as they are called, catching up shock waves. The scope of work is to give a classification of the shock-wave structures that arise in this type of interaction of shock waves, and the area of their existence. Intersection of unidirectional shock waves results in arising of a shock-wave structure at the intersection point, which contains the main shock wave, tangential discontinuity and one more reflected gas-dynamic discontinuity of unknown beforehand type. The problem of determining the type of reflected discontinuity is the main problem that one has to solve in the study of catching shock waves interference. Main results.The paper presents the pictures of shock-wave structures arising at the interaction of catching up shock waves. The areas with a regular and irregular unidirectional interaction of shocks are described. Characteristic shock-wave structures are of greatest interest, where reflected gas-dynamic discontinuity degenerates into discontinuous characteristics. Such structures have a number of extreme properties. We have found the areas of existence for such shock-wave structures. There are also areas in which the steady-state solution is not available. The latter has determined revival of interest for the theoretical study of the problem, because the facts of sudden shock-wave structure destruction inside the air intake of supersonic aircrafts at high Mach numbers have been discovered. Practical significance.The theory of interference for unidirectional shock waves and design procedure are usable in the design of supersonic air intakes. It is also relevant for application possibility investigation of catching up oblique shock waves to create overcompressed detonation in perspective detonation air-jet and rocket engines.

  13. Shock tube Multiphase Experiments

    Middlebrooks, John; Allen, Roy; Paudel, Manoj; Young, Calvin; Musick, Ben; McFarland, Jacob

    2017-11-01

    Shock driven multiphase instabilities (SDMI) are unique physical phenomena that have far-reaching practical applications in engineering and science. The instability is present in high energy explosions, scramjet combustors, and supernovae events. The SDMI arises when a multiphase interface is impulsively accelerated by the passage of a shockwave. It is similar in development to the Richtmyer-Meshkov (RM) instability however, particle-to-gas coupling is the driving mechanism of the SDMI. As particle effects such as lag and phase change become more prominent, the SDMI's development begins to significantly deviate from the RM instability. We have developed an experiment for studying the SDMI in our shock tube facility. In our experiments, a multiphase interface is created using a laminar jet and flowed into the shock tube where it is accelerated by the passage of a planar shockwave. The interface development is captured using CCD cameras synchronized with planar laser illumination. This talk will give an overview of new experiments conducted to examine the development of a shocked cylindrical multiphase interface. The effects of Atwood number, particle size, and a second acceleration (reshock) of the interface will be discussed.

  14. Teleconnected food supply shocks

    Bren d'Amour, Christopher; Wenz, Leonie; Kalkuhl, Matthias; Steckel, Jan Christoph; Creutzig, Felix

    2016-03-01

    The 2008-2010 food crisis might have been a harbinger of fundamental climate-induced food crises with geopolitical implications. Heat-wave-induced yield losses in Russia and resulting export restrictions led to increases in market prices for wheat across the Middle East, likely contributing to the Arab Spring. With ongoing climate change, temperatures and temperature variability will rise, leading to higher uncertainty in yields for major nutritional crops. Here we investigate which countries are most vulnerable to teleconnected supply-shocks, i.e. where diets strongly rely on the import of wheat, maize, or rice, and where a large share of the population is living in poverty. We find that the Middle East is most sensitive to teleconnected supply shocks in wheat, Central America to supply shocks in maize, and Western Africa to supply shocks in rice. Weighing with poverty levels, Sub-Saharan Africa is most affected. Altogether, a simultaneous 10% reduction in exports of wheat, rice, and maize would reduce caloric intake of 55 million people living in poverty by about 5%. Export bans in major producing regions would put up to 200 million people below the poverty line at risk, 90% of which live in Sub-Saharan Africa. Our results suggest that a region-specific combination of national increases in agricultural productivity and diversification of trade partners and diets can effectively decrease future food security risks.

  15. A Telehealth System for Remote Auditory Evoked Potential Monitoring

    Millan, Jorge; Yunda, Leonardo

    2013-01-01

    A portable, Internet-based EEG/Auditory Evoked Potential (AEP) monitoring system was developed for remote electrophysiological studies during sleep. The system records EEG/AEP simultaneously at the subject?s home for increased comfort and flexibility. The system provides simultaneous recording and remote viewing of EEG, EMG and EOG waves and allows on-line averaging of auditory evoked potentials. The design allows the recording of all major AEP components (brainstem, middle and late latency E...

  16. Vibration and muscle contraction affect somatosensory evoked potentials

    Cohen, LG; Starr, A

    1985-01-01

    We recorded potentials evoked by specific somatosensory stimuli over peripheral nerve, spinal cord, and cerebral cortex. Vibration attenuated spinal and cerebral potentials evoked by mixed nerve and muscle spindle stimulation; in one subject that was tested, there was no effect on cutaneous input. Presynaptic inhibition of Ia input in the spinal cord and muscle spindle receptor occupancy are probably the responsible mechanisms. In contrast, muscle contraction attenuated cerebral potentials to...

  17. Brain-immune interaction accompanying odor-evoked autobiographic memory.

    Matsunaga, Masahiro; Bai, Yu; Yamakawa, Kaori; Toyama, Asako; Kashiwagi, Mitsuyoshi; Fukuda, Kazuyuki; Oshida, Akiko; Sanada, Kazue; Fukuyama, Seisuke; Shinoda, Jun; Yamada, Jitsuhiro; Sadato, Norihiro; Ohira, Hideki

    2013-01-01

    The phenomenon in which a certain smell evokes a specific memory is known as the Proust phenomenon. Odor-evoked autobiographic memories are more emotional than those elicited by other sensory stimuli. The results of our previous study indicated that odor-evoked autobiographic memory accompanied by positive emotions has remarkable effects on various psychological and physiological activities, including the secretion of cytokines, which are immune-signaling molecules that modulate systemic inflammation. In this study, we aimed to clarify the neural substrates associated with the interaction between odor-evoked autobiographic memory and peripheral circulating cytokines. We recruited healthy male and female volunteers and investigated the association between brain responses and the concentration of several cytokines in the plasma by using positron emission tomography (PET) recordings when an autographic memory was evoked in participants by asking them to smell an odor that was nostalgic to them. Participants experienced positive emotions and autobiographic memories when nostalgic odors were presented to them. The levels of peripheral proinflammatory cytokines, such as the tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), were significantly reduced after experiencing odor-evoked autobiographic memory. Subtraction analysis of PET images indicated that the medial orbitofrontal cortex (mOFC) and precuneus/posterior cingulate cortex (PCC) were significantly activated during experiences of odor-evoked autobiographic memory. Furthermore, a correlation analysis indicated that activities of the mOFC and precuneus/PCC were negatively correlated with IFN-γ concentration. These results indicate that the neural networks including the precuneus/PCC and mOFC might regulate the secretion of peripheral proinflammatory cytokines during the experience of odor-evoked autobiographic memories accompanied with positive emotions.

  18. Brain–Immune Interaction Accompanying Odor-Evoked Autobiographic Memory

    Matsunaga, Masahiro; Bai, Yu; Yamakawa, Kaori; Toyama, Asako; Kashiwagi, Mitsuyoshi; Fukuda, Kazuyuki; Oshida, Akiko; Sanada, Kazue; Fukuyama, Seisuke; Shinoda, Jun; Yamada, Jitsuhiro; Sadato, Norihiro; Ohira, Hideki

    2013-01-01

    The phenomenon in which a certain smell evokes a specific memory is known as the Proust phenomenon. Odor-evoked autobiographic memories are more emotional than those elicited by other sensory stimuli. The results of our previous study indicated that odor-evoked autobiographic memory accompanied by positive emotions has remarkable effects on various psychological and physiological activities, including the secretion of cytokines, which are immune-signaling molecules that modulate systemic inflammation. In this study, we aimed to clarify the neural substrates associated with the interaction between odor-evoked autobiographic memory and peripheral circulating cytokines. We recruited healthy male and female volunteers and investigated the association between brain responses and the concentration of several cytokines in the plasma by using positron emission tomography (PET) recordings when an autographic memory was evoked in participants by asking them to smell an odor that was nostalgic to them. Participants experienced positive emotions and autobiographic memories when nostalgic odors were presented to them. The levels of peripheral proinflammatory cytokines, such as the tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), were significantly reduced after experiencing odor-evoked autobiographic memory. Subtraction analysis of PET images indicated that the medial orbitofrontal cortex (mOFC) and precuneus/posterior cingulate cortex (PCC) were significantly activated during experiences of odor-evoked autobiographic memory. Furthermore, a correlation analysis indicated that activities of the mOFC and precuneus/PCC were negatively correlated with IFN-γ concentration. These results indicate that the neural networks including the precuneus/PCC and mOFC might regulate the secretion of peripheral proinflammatory cytokines during the experience of odor-evoked autobiographic memories accompanied with positive emotions. PMID:23977312

  19. Brain-immune interaction accompanying odor-evoked autobiographic memory.

    Masahiro Matsunaga

    Full Text Available The phenomenon in which a certain smell evokes a specific memory is known as the Proust phenomenon. Odor-evoked autobiographic memories are more emotional than those elicited by other sensory stimuli. The results of our previous study indicated that odor-evoked autobiographic memory accompanied by positive emotions has remarkable effects on various psychological and physiological activities, including the secretion of cytokines, which are immune-signaling molecules that modulate systemic inflammation. In this study, we aimed to clarify the neural substrates associated with the interaction between odor-evoked autobiographic memory and peripheral circulating cytokines. We recruited healthy male and female volunteers and investigated the association between brain responses and the concentration of several cytokines in the plasma by using positron emission tomography (PET recordings when an autographic memory was evoked in participants by asking them to smell an odor that was nostalgic to them. Participants experienced positive emotions and autobiographic memories when nostalgic odors were presented to them. The levels of peripheral proinflammatory cytokines, such as the tumor necrosis factor-α (TNF-α and interferon-γ (IFN-γ, were significantly reduced after experiencing odor-evoked autobiographic memory. Subtraction analysis of PET images indicated that the medial orbitofrontal cortex (mOFC and precuneus/posterior cingulate cortex (PCC were significantly activated during experiences of odor-evoked autobiographic memory. Furthermore, a correlation analysis indicated that activities of the mOFC and precuneus/PCC were negatively correlated with IFN-γ concentration. These results indicate that the neural networks including the precuneus/PCC and mOFC might regulate the secretion of peripheral proinflammatory cytokines during the experience of odor-evoked autobiographic memories accompanied with positive emotions.

  20. STEREO interplanetary shocks and foreshocks

    Blanco-Cano, X.; Kajdič, P.; Aguilar-Rodríguez, E.; Russell, C. T.; Jian, L. K.; Luhmann, J. G.

    2013-01-01

    We use STEREO data to study shocks driven by stream interactions and the waves associated with them. During the years of the extended solar minimum 2007-2010, stream interaction shocks have Mach numbers between 1.1-3.8 and θ Bn ∼20-86°. We find a variety of waves, including whistlers and low frequency fluctuations. Upstream whistler waves may be generated at the shock and upstream ultra low frequency (ULF) waves can be driven locally by ion instabilities. The downstream wave spectra can be formed by both, locally generated perturbations, and shock transmitted waves. We find that many quasiperpendicular shocks can be accompanied by ULF wave and ion foreshocks, which is in contrast to Earth's bow shock. Fluctuations downstream of quasi-parallel shocks tend to have larger amplitudes than waves downstream of quasi-perpendicular shocks. Proton foreshocks of shocks driven by stream interactions have extensions dr ≤0.05 AU. This is smaller than foreshock extensions for ICME driven shocks. The difference in foreshock extensions is related to the fact that ICME driven shocks are formed closer to the Sun and therefore begin to accelerate particles very early in their existence, while stream interaction shocks form at ∼1 AU and have been producing suprathermal particles for a shorter time.

  1. STEREO interplanetary shocks and foreshocks

    Blanco-Cano, X. [Instituto de Geofisica, UNAM, CU, Coyoacan 04510 DF (Mexico); Kajdic, P. [IRAP-University of Toulouse, CNRS, Toulouse (France); Aguilar-Rodriguez, E. [Instituto de Geofisica, UNAM, Morelia (Mexico); Russell, C. T. [ESS and IGPP, University of California, Los Angeles, 603 Charles Young Drive, Los Angeles, CA 90095 (United States); Jian, L. K. [NASA Goddard Space Flight Center, Greenbelt, MD and University of Maryland, College Park, MD (United States); Luhmann, J. G. [SSL, University of California Berkeley (United States)

    2013-06-13

    We use STEREO data to study shocks driven by stream interactions and the waves associated with them. During the years of the extended solar minimum 2007-2010, stream interaction shocks have Mach numbers between 1.1-3.8 and {theta}{sub Bn}{approx}20-86 Degree-Sign . We find a variety of waves, including whistlers and low frequency fluctuations. Upstream whistler waves may be generated at the shock and upstream ultra low frequency (ULF) waves can be driven locally by ion instabilities. The downstream wave spectra can be formed by both, locally generated perturbations, and shock transmitted waves. We find that many quasiperpendicular shocks can be accompanied by ULF wave and ion foreshocks, which is in contrast to Earth's bow shock. Fluctuations downstream of quasi-parallel shocks tend to have larger amplitudes than waves downstream of quasi-perpendicular shocks. Proton foreshocks of shocks driven by stream interactions have extensions dr {<=}0.05 AU. This is smaller than foreshock extensions for ICME driven shocks. The difference in foreshock extensions is related to the fact that ICME driven shocks are formed closer to the Sun and therefore begin to accelerate particles very early in their existence, while stream interaction shocks form at {approx}1 AU and have been producing suprathermal particles for a shorter time.

  2. Beyond the evoked/intrinsic neural process dichotomy

    Taylor Bolt

    2018-03-01

    Full Text Available Contemporary functional neuroimaging research has increasingly focused on characterization of intrinsic or “spontaneous” brain activity. Analysis of intrinsic activity is often contrasted with analysis of task-evoked activity that has traditionally been the focus of cognitive neuroscience. But does this evoked/intrinsic dichotomy adequately characterize human brain function? Based on empirical data demonstrating a close functional interdependence between intrinsic and task-evoked activity, we argue that the dichotomy between intrinsic and task-evoked activity as unobserved contributions to brain activity is artificial. We present an alternative picture of brain function in which the brain’s spatiotemporal dynamics do not consist of separable intrinsic and task-evoked components, but reflect the enaction of a system of mutual constraints to move the brain into and out of task-appropriate functional configurations. According to this alternative picture, cognitive neuroscientists are tasked with describing both the temporal trajectory of brain activity patterns across time, and the modulation of this trajectory by task states, without separating this process into intrinsic and task-evoked components. We argue that this alternative picture of brain function is best captured in a novel explanatory framework called enabling constraint. Overall, these insights call for a reconceptualization of functional brain activity, and should drive future methodological and empirical efforts.

  3. Muscle synergies evoked by microstimulation are preferentially encoded during behavior

    Simon Alexander Overduin

    2014-03-01

    Full Text Available Electrical microstimulation studies provide some of the most direct evidence for the neural representation of muscle synergies. These synergies, i.e. coordinated activations of groups of muscles, have been proposed as building blocks for the construction of motor behaviors by the nervous system. Intraspinal or intracortical microstimulation has been shown to evoke muscle patterns that can be resolved into a small set of synergies similar to those seen in natural behavior. However, questions remain about the validity of microstimulation as a probe of neural function, particularly given the relatively long trains of supratheshold stimuli used in these studies. Here, we examined whether muscle synergies evoked during intracortical microstimulation in two rhesus macaques were similarly encoded by nearby motor cortical units during a purely voluntary behavior involving object reach, grasp, and carry movements. At each microstimulation site we identified the synergy most strongly evoked among those extracted from muscle patterns evoked over all microstimulation sites. For each cortical unit recorded at the same microstimulation site, we then identified the synergy most strongly encoded among those extracted from muscle patterns recorded during the voluntary behavior. We found that the synergy most strongly evoked at an intracortical microstimulation site matched the synergy most strongly encoded by proximal units more often than expected by chance. These results suggest a common neural substrate for microstimulation-evoked motor responses and for the generation of muscle patterns during natural behaviors.

  4. Shock Dynamics in Stellar Outbursts. I. Shock Formation

    Ro, Stephen; Matzner, Christopher D., E-mail: ro@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada)

    2017-05-20

    Wave-driven outflows and non-disruptive explosions have been implicated in pre-supernova outbursts, supernova impostors, luminous blue variable eruptions, and some narrow-line and superluminous supernovae. To model these events, we investigate the dynamics of stars set in motion by strong acoustic pulses and wave trains, focusing on nonlinear wave propagation, shock formation, and an early phase of the development of a weak shock. We identify the shock formation radius, showing that a heuristic estimate based on crossing characteristics matches an exact expansion around the wave front and verifying both with numerical experiments. Our general analytical condition for shock formation applies to one-dimensional motions within any static environment, including both eruptions and implosions. We also consider the early phase of shock energy dissipation. We find that waves of super-Eddington acoustic luminosity always create shocks, rather than damping by radiative diffusion. Therefore, shock formation is integral to super-Eddington outbursts.

  5. Grain destruction in interstellar shocks

    Seab, C.G.; Shull, J.M.

    1984-01-01

    One of the principal methods for removing grains from the Interstellar Medium is to destroy them in shock waves. Previous theoretical studies of shock destruction have generally assumed only a single size and type of grain; most do not account for the effect of the grain destruction on the structure of the shock. Earlier calculations have been improved in three ways: first, by using a ''complete'' grain model including a distribution of sizes and types of grains; second, by using a self-consistent shock structure that incorporates the changing elemental depletions as the grains are destroyed; and third, by calculating the shock-processed ultraviolet extinction curves for comparison with observations. (author)

  6. Bubble Dynamics and Shock Waves

    2013-01-01

    This volume of the Shock Wave Science and Technology Reference Library is concerned with the interplay between bubble dynamics and shock waves. It is divided into four parts containing twelve chapters written by eminent scientists. Topics discussed include shock wave emission by laser generated bubbles (W Lauterborn, A Vogel), pulsating bubbles near boundaries (DM Leppinen, QX Wang, JR Blake), interaction of shock waves with bubble clouds (CD Ohl, SW Ohl), shock propagation in polydispersed bubbly liquids by model equations (K Ando, T Colonius, CE Brennen. T Yano, T Kanagawa,  M Watanabe, S Fujikawa) and by DNS (G Tryggvason, S Dabiri), shocks in cavitating flows (NA Adams, SJ Schmidt, CF Delale, GH Schnerr, S Pasinlioglu) together with applications involving encapsulated bubble dynamics in imaging (AA Doinikov, A Novell, JM Escoffre, A Bouakaz),  shock wave lithotripsy (P Zhong), sterilization of ships’ ballast water (A Abe, H Mimura) and bubbly flow model of volcano eruptions ((VK Kedrinskii, K Takayama...

  7. The paradox of music-evoked sadness: an online survey.

    Liila Taruffi

    Full Text Available This study explores listeners' experience of music-evoked sadness. Sadness is typically assumed to be undesirable and is therefore usually avoided in everyday life. Yet the question remains: Why do people seek and appreciate sadness in music? We present findings from an online survey with both Western and Eastern participants (N = 772. The survey investigates the rewarding aspects of music-evoked sadness, as well as the relative contribution of listener characteristics and situational factors to the appreciation of sad music. The survey also examines the different principles through which sadness is evoked by music, and their interaction with personality traits. Results show 4 different rewards of music-evoked sadness: reward of imagination, emotion regulation, empathy, and no "real-life" implications. Moreover, appreciation of sad music follows a mood-congruent fashion and is greater among individuals with high empathy and low emotional stability. Surprisingly, nostalgia rather than sadness is the most frequent emotion evoked by sad music. Correspondingly, memory was rated as the most important principle through which sadness is evoked. Finally, the trait empathy contributes to the evocation of sadness via contagion, appraisal, and by engaging social functions. The present findings indicate that emotional responses to sad music are multifaceted, are modulated by empathy, and are linked with a multidimensional experience of pleasure. These results were corroborated by a follow-up survey on happy music, which indicated differences between the emotional experiences resulting from listening to sad versus happy music. This is the first comprehensive survey of music-evoked sadness, revealing that listening to sad music can lead to beneficial emotional effects such as regulation of negative emotion and mood as well as consolation. Such beneficial emotional effects constitute the prime motivations for engaging with sad music in everyday life.

  8. The Paradox of Music-Evoked Sadness: An Online Survey

    Taruffi, Liila; Koelsch, Stefan

    2014-01-01

    This study explores listeners’ experience of music-evoked sadness. Sadness is typically assumed to be undesirable and is therefore usually avoided in everyday life. Yet the question remains: Why do people seek and appreciate sadness in music? We present findings from an online survey with both Western and Eastern participants (N = 772). The survey investigates the rewarding aspects of music-evoked sadness, as well as the relative contribution of listener characteristics and situational factors to the appreciation of sad music. The survey also examines the different principles through which sadness is evoked by music, and their interaction with personality traits. Results show 4 different rewards of music-evoked sadness: reward of imagination, emotion regulation, empathy, and no “real-life” implications. Moreover, appreciation of sad music follows a mood-congruent fashion and is greater among individuals with high empathy and low emotional stability. Surprisingly, nostalgia rather than sadness is the most frequent emotion evoked by sad music. Correspondingly, memory was rated as the most important principle through which sadness is evoked. Finally, the trait empathy contributes to the evocation of sadness via contagion, appraisal, and by engaging social functions. The present findings indicate that emotional responses to sad music are multifaceted, are modulated by empathy, and are linked with a multidimensional experience of pleasure. These results were corroborated by a follow-up survey on happy music, which indicated differences between the emotional experiences resulting from listening to sad versus happy music. This is the first comprehensive survey of music-evoked sadness, revealing that listening to sad music can lead to beneficial emotional effects such as regulation of negative emotion and mood as well as consolation. Such beneficial emotional effects constitute the prime motivations for engaging with sad music in everyday life. PMID:25330315

  9. The paradox of music-evoked sadness: an online survey.

    Taruffi, Liila; Koelsch, Stefan

    2014-01-01

    This study explores listeners' experience of music-evoked sadness. Sadness is typically assumed to be undesirable and is therefore usually avoided in everyday life. Yet the question remains: Why do people seek and appreciate sadness in music? We present findings from an online survey with both Western and Eastern participants (N = 772). The survey investigates the rewarding aspects of music-evoked sadness, as well as the relative contribution of listener characteristics and situational factors to the appreciation of sad music. The survey also examines the different principles through which sadness is evoked by music, and their interaction with personality traits. Results show 4 different rewards of music-evoked sadness: reward of imagination, emotion regulation, empathy, and no "real-life" implications. Moreover, appreciation of sad music follows a mood-congruent fashion and is greater among individuals with high empathy and low emotional stability. Surprisingly, nostalgia rather than sadness is the most frequent emotion evoked by sad music. Correspondingly, memory was rated as the most important principle through which sadness is evoked. Finally, the trait empathy contributes to the evocation of sadness via contagion, appraisal, and by engaging social functions. The present findings indicate that emotional responses to sad music are multifaceted, are modulated by empathy, and are linked with a multidimensional experience of pleasure. These results were corroborated by a follow-up survey on happy music, which indicated differences between the emotional experiences resulting from listening to sad versus happy music. This is the first comprehensive survey of music-evoked sadness, revealing that listening to sad music can lead to beneficial emotional effects such as regulation of negative emotion and mood as well as consolation. Such beneficial emotional effects constitute the prime motivations for engaging with sad music in everyday life.

  10. Cortical evoked potentials to an auditory illusion: binaural beats.

    Pratt, Hillel; Starr, Arnold; Michalewski, Henry J; Dimitrijevic, Andrew; Bleich, Naomi; Mittelman, Nomi

    2009-08-01

    To define brain activity corresponding to an auditory illusion of 3 and 6Hz binaural beats in 250Hz or 1000Hz base frequencies, and compare it to the sound onset response. Event-Related Potentials (ERPs) were recorded in response to unmodulated tones of 250 or 1000Hz to one ear and 3 or 6Hz higher to the other, creating an illusion of amplitude modulations (beats) of 3Hz and 6Hz, in base frequencies of 250Hz and 1000Hz. Tones were 2000ms in duration and presented with approximately 1s intervals. Latency, amplitude and source current density estimates of ERP components to tone onset and subsequent beats-evoked oscillations were determined and compared across beat frequencies with both base frequencies. All stimuli evoked tone-onset P(50), N(100) and P(200) components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude with the low base frequency and to the low beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left lateral and inferior temporal lobe areas in all stimulus conditions. Onset-evoked components were not different across stimulus conditions; P(50) had significantly different sources than the beats-evoked oscillations; and N(100) and P(200) sources located to the same temporal lobe regions as beats-evoked oscillations, but were bilateral and also included frontal and parietal contributions. Neural activity with slightly different volley frequencies from left and right ear converges and interacts in the central auditory brainstem pathways to generate beats of neural activity to modulate activities in the left temporal lobe, giving rise to the illusion of binaural beats. Cortical potentials recorded to binaural beats are distinct from onset responses. Brain activity corresponding to an auditory illusion of low frequency beats can be recorded from the scalp.

  11. Adjustable Shock Absorbers

    Adamiec, Radek

    2012-01-01

    Bakalářská práce obsahuje přehled používaných tlumičů osobních automobilů, závodních automobilů a motocyklů. Jsou zde popsány systémy t lumením, konstrukce tlumičů a vidlic používaných u motocyklů. Dále je zde přehled prvků používaných u podvozků automobilů. This bachelor´s thesis contains the survey of the shock absorbers of passenger cars, racing cars and motorcycles. Are described damping systems, the design used shock absorbers and forks for motorcycles. Then there is the list of the e...

  12. Radiative relativistic shock adiabate

    Tsintsadze, L.N.; Nishikawa, K.

    1997-01-01

    The influences of thermal radiation on the state equation of shock waves, derived in the previous paper [L. N. Tsintsadze, Phys. Plasmas 2, 4462 (1995)], are studied and a series of relations of thermodynamic quantities that hold for shock waves are derived. It is shown that the presence of radiation can strongly change the compressibility of the plasma. It is well known that for polytropic gases the compressibility cannot change more than four times the initial value in the case of nonrelativistic temperatures. The numerical calculations show that there are no such restrictions, when the radiation energy exceeds the kinetic energy of the plasma. The ultrarelativistic temperature range is also covered in our numerical calculations. Also studied are the influences of the radiation on the PT and the TV diagrams. A significant modification due to radiation is found in every case studied. copyright 1997 American Institute of Physics

  13. POSTURAL SHOCK IN PREGNANCY

    Wilkening, Ralph L.; Knauer, John; Larson, Roger K.

    1955-01-01

    Signs and symptoms of shock may be produced in some patients in late pregnancy by putting them in the dorsal recumbent posture. Change from this position will relieve the condition. The features of the supine hypotensive syndrome can be duplicated by applying pressure to the abdomen with the patient in a lateral position. The postural variations of venous pressure, blood pressure, and pulse appear to be due to obstruction of venous return from the lower portion of the body caused by the large uterus of late pregnancy compressing the vena cava. When shock is observed in a woman in late pregnancy, she should be turned to a lateral position before more active measures of treatment are begun. ImagesFigure 1. PMID:14351983

  14. Bow shock data analysis

    Zipf, Edward C.; Erdman, Peeter W.

    1994-08-01

    The University of Pittsburgh Space Physics Group in collaboration with the Army Research Office (ARO) modeling team has completed a systematic organization of the shock and plume spectral data and the electron temperature and density measurements obtained during the BowShock I and II rocket flights which have been submitted to the AEDC Data Center, has verified the presence of CO Cameron band emission during the Antares engine burn and for an extended period of time in the post-burn plume, and have adapted 3-D radiation entrapment codes developed by the University of Pittsburgh to study aurora and other atmospheric phenomena that involve significant spatial effects to investigate the vacuum ultraviolet (VUV) and extreme ultraviolet (EUV) envelope surrounding the re-entry that create an extensive plasma cloud by photoionization.

  15. Shock Isolation Elements Testing for High Input Loadings. Volume III. Mechanical Shock Isolation Elements.

    SHOCK ABSORBERS ), (*GUIDED MISSILE SILOS, SHOCK ABSORBERS ), (*SPRINGS, (*SHOCK(MECHANICS), REDUCTION), TORSION BARS, ELASTOMERS, DAMPING, EQUATIONS OF MOTION, MODEL TESTS, TEST METHODS, NUCLEAR EXPLOSIONS, HARDENING.

  16. Shock resistance testing

    Pouard, M.

    1984-03-01

    In the framework of mechanical tests and to answer the different requests for tests, the T.C.R (Transport Conditionnement et Retraitement) laboratory got test facilities. These installations allow to carry out tests of resistance to shocks, mainly at the safety level of components of nuclear power plants, mockups of transport casks for fuel elements and transport containers for radioactive materials. They include a tower and a catapult. This paper give a decription of the facilities and explain their operation way [fr

  17. On Modeling Risk Shocks

    Dorofeenko, Victor; Lee, Gabriel; Salyer, Kevin; Strobel, Johannes

    2016-01-01

    Within the context of a financial accelerator model, we model time-varying uncertainty (i.e. risk shocks) through the use of a mixture Normal model with time variation in the weights applied to the underlying distributions characterizing entrepreneur productivity. Specifically, we model capital producers (i.e. the entrepreneurs) as either low-risk (relatively small second moment for productivity) and high-risk (relatively large second moment for productivity) and the fraction of both types is...

  18. The Shock Doctrine

    Dionysios K. Solomos; Dimitrios N. Koumparoulis

    2011-01-01

    Naomi Klein attempts to redefine the economic history discovering the historical continuities and to reveal the neoliberal theory which functions via the utilization of specific “tools”. The state of shock is the key for the opponents of Chicago School and Milton Friedman in order for them to establish neoliberal policies and to promote the deregulated capitalism which includes less welfare state, less public sector, less regulation, weakened labor unions, privatizations and laissez-faire. Th...

  19. Characterization of shocked beryllium

    Papin P.A.

    2012-08-01

    Full Text Available While numerous studies have investigated the low-strain-rate constitutive response of beryllium, the combined influence of high strain rate and temperature on the mechanical behavior and microstructure of beryllium has received limited attention over the last 40 years. In the current work, high strain rate tests were conducted using both explosive drive and a gas gun to accelerate the material. Prior studies have focused on tensile loading behavior, or limited conditions of dynamic strain rate and/or temperature. Two constitutive strength (plasticity models, the Preston-Tonks-Wallace (PTW and Mechanical Threshold Stress (MTS models, were calibrated using common quasi-static and Hopkinson bar data. However, simulations with the two models give noticeably different results when compared with the measured experimental wave profiles. The experimental results indicate that, even if fractured by the initial shock loading, the Be remains sufficiently intact to support a shear stress following partial release and subsequent shock re-loading. Additional “arrested” drive shots were designed and tested to minimize the reflected tensile pulse in the sample. These tests were done to both validate the model and to put large shock induced compressive loads into the beryllium sample.

  20. Selfsimilar time dependent shock structures

    Beck, R.; Drury, L.O.

    1985-01-01

    Diffusive shock acceleration as an astrophysical mechanism for accelerating charged particles has the advantage of being highly efficient. This means however that the theory is of necessity nonlinear; the reaction of the accelerated particles on the shock structure and the acceleration process must be self-consistently included in any attempt to develop a complete theory of diffusive shock acceleration. Considerable effort has been invested in attempting, at least partially, to do this and it has become clear that in general either the maximum particle energy must be restricted by introducing additional loss processes into the problem or the acceleration must be treated as a time dependent problem (Drury, 1984). It is concluded that stationary modified shock structures can only exist for strong shocks if additional loss processes limit the maximum energy a particle can attain. This is certainly possible and if it occurs the energy loss from the shock will lead to much greater shock compressions. It is however equally possible that no such processes exist and we must then ask what sort of nonstationary shock structure develops. The same argument which excludes stationary structures also rules out periodic solutions and indeed any solution where the width of the shock remains bounded. It follows that the width of the shock must increase secularly with time and it is natural to examine the possibility of selfsimilar time dependent solutions

  1. Selfsimilar time dependent shock structures

    Beck, R.; Drury, L. O.

    1985-01-01

    Diffusive shock acceleration as an astrophysical mechanism for accelerating charged particles has the advantage of being highly efficient. This means however that the theory is of necessity nonlinear; the reaction of the accelerated particles on the shock structure and the acceleration process must be self-consistently included in any attempt to develop a complete theory of diffusive shock acceleration. Considerable effort has been invested in attempting, at least partially, to do this and it has become clear that in general either the maximum particle energy must be restricted by introducing additional loss processes into the problem or the acceleration must be treated as a time dependent problem (Drury, 1984). It is concluded that stationary modified shock structures can only exist for strong shocks if additional loss processes limit the maximum energy a particle can attain. This is certainly possible and if it occurs the energy loss from the shock will lead to much greater shock compressions. It is however equally possible that no such processes exist and we must then ask what sort of nonstationary shock structure develops. The ame argument which excludes stationary structures also rules out periodic solutions and indeed any solution where the width of the shock remains bounded. It follows that the width of the shock must increase secularly with time and it is natural to examine the possibility of selfsimilar time dependent solutions.

  2. The Presence of Turbulent and Ordered Local Structure within the ICME Shock-sheath and Its Contribution to Forbush Decrease

    Shaikh, Zubair; Bhaskar, Ankush [Indian Institute of Geomagnetism (IIG), New Panvel, Navi Mumbai-410218 (India); Raghav, Anil, E-mail: raghavanil1984@gmail.com [University Department of Physics, University of Mumbai, Vidyanagari, Santacruz (E), Mumbai-400098 (India)

    2017-08-01

    The transient interplanetary disturbances evoke short-time cosmic-ray flux decrease, which is known as Forbush decrease. The traditional model and understanding of Forbush decrease suggest that the sub-structure of an interplanetary counterpart of coronal mass ejection (ICME) independently contributes to cosmic-ray flux decrease. These sub-structures, shock-sheath, and magnetic cloud (MC) manifest as classical two-step Forbush decrease. The recent work by Raghav et al. has shown multi-step decreases and recoveries within the shock-sheath. However, this cannot be explained by the ideal shock-sheath barrier model. Furthermore, they suggested that local structures within the ICME’s sub-structure (MC and shock-sheath) could explain this deviation of the FD profile from the classical FD. Therefore, the present study attempts to investigate the cause of multi-step cosmic-ray flux decrease and respective recovery within the shock-sheath in detail. A 3D-hodogram method is utilized to obtain more details regarding the local structures within the shock-sheath. This method unambiguously suggests the formation of small-scale local structures within the ICME (shock-sheath and even in MC). Moreover, the method could differentiate the turbulent and ordered interplanetary magnetic field (IMF) regions within the sub-structures of ICME. The study explicitly suggests that the turbulent and ordered IMF regions within the shock-sheath do influence cosmic-ray variations differently.

  3. The effects of curiosity-evoking events on activity enjoyment.

    Isikman, Elif; MacInnis, Deborah J; Ülkümen, Gülden; Cavanaugh, Lisa A

    2016-09-01

    Whereas prior literature has studied the positive effects of curiosity-evoking events that are integral to focal activities, we explore whether and how a curiosity-evoking event that is incidental to a focal activity induces negative outcomes for enjoyment. Four experiments and 1 field study demonstrate that curiosity about an event that is incidental to an activity in which individuals are engaged, significantly affects enjoyment of a concurrent activity. The reason why is that curiosity diverts attention away from the concurrent activity and focuses attention on the curiosity-evoking event. Thus, curiosity regarding an incidental event decreases enjoyment of a positive focal activity but increases enjoyment of a negative focal activity. PsycINFO Database Record (c) 2016 APA, all rights reserved

  4. Do video games evoke specific types of epileptic seizures?

    Piccioli, Marta; Vigevano, Federico; Buttinelli, Carla; Kasteleijn-Nolst Trenité, Dorothée G A

    2005-11-01

    We determined whether epileptic clinical manifestations evoked by playing video games (VG) differ from those evoked by intermittent photic stimulation (IPS) or striped patterns (P). We exposed nine children who had TV- and VG-evoked seizures in daily life to 12 VG after standardized photic stimulation and pattern stimulation. Their EEGs were recorded continuously, analyzed, and then correlated with a video of their behavior. Similar types of clinical signs were seen during VG, P, and IPS, but the signs we observed were more subtle during the VG. Eight patients showed a clear lateralization. A new observation was the lowering of the eyelids to a state of half-closed. Our study suggests that the type of visual stimulus provoking a photoparoxysmal response or seizure is not particularly relevant. The children belonged to different epilepsy groups, and our findings add to the discussion on the boundaries of the epilepsy types.

  5. Stimulator with arbitrary waveform for auditory evoked potentials

    Martins, H R; Romao, M; Placido, D; Provenzano, F; Tierra-Criollo, C J

    2007-01-01

    The technological improvement helps many medical areas. The audiometric exams involving the auditory evoked potentials can make better diagnoses of auditory disorders. This paper proposes the development of a stimulator based on Digital Signal Processor. This stimulator is the first step of an auditory evoked potential system based on the ADSP-BF533 EZ KIT LITE (Analog Devices Company - USA). The stimulator can generate arbitrary waveform like Sine Waves, Modulated Amplitude, Pulses, Bursts and Pips. The waveforms are generated through a graphical interface programmed in C++ in which the user can define the parameters of the waveform. Furthermore, the user can set the exam parameters as number of stimuli, time with stimulation (Time ON) and time without stimulus (Time OFF). In future works will be implemented another parts of the system that includes the acquirement of electroencephalogram and signal processing to estimate and analyze the evoked potential

  6. Stimulator with arbitrary waveform for auditory evoked potentials

    Martins, H R; Romao, M; Placido, D; Provenzano, F; Tierra-Criollo, C J [Universidade Federal de Minas Gerais (UFMG), Departamento de Engenharia Eletrica (DEE), Nucleo de Estudos e Pesquisa em Engenharia Biomedica NEPEB, Av. Ant. Carlos, 6627, sala 2206, Pampulha, Belo Horizonte, MG, 31.270-901 (Brazil)

    2007-11-15

    The technological improvement helps many medical areas. The audiometric exams involving the auditory evoked potentials can make better diagnoses of auditory disorders. This paper proposes the development of a stimulator based on Digital Signal Processor. This stimulator is the first step of an auditory evoked potential system based on the ADSP-BF533 EZ KIT LITE (Analog Devices Company - USA). The stimulator can generate arbitrary waveform like Sine Waves, Modulated Amplitude, Pulses, Bursts and Pips. The waveforms are generated through a graphical interface programmed in C++ in which the user can define the parameters of the waveform. Furthermore, the user can set the exam parameters as number of stimuli, time with stimulation (Time ON) and time without stimulus (Time OFF). In future works will be implemented another parts of the system that includes the acquirement of electroencephalogram and signal processing to estimate and analyze the evoked potential.

  7. Risk shocks and housing markets

    Dorofeenko, Viktor; Lee, Gabriel S.; Salyer, Kevin D.

    2010-01-01

    Abstract: This paper analyzes the role of uncertainty in a multi-sector housing model with financial frictions. We include time varying uncertainty (i.e. risk shocks) in the technology shocks that affect housing production. The analysis demonstratesthat risk shocks to the housing production sector are a quantitatively important impulse mechanism for the business cycle. Also, we demonstrate that bankruptcy costs act as an endogenous markup factor in housing prices; as a consequence, the volati...

  8. Health shocks and risk aversion.

    Decker, Simon; Schmitz, Hendrik

    2016-12-01

    We empirically assess whether a health shock influences individual risk aversion. We use grip strength data to obtain an objective health shock indicator. In order to account for the non-random nature of our data regression-adjusted matching is employed. Risk preferences are traditionally assumed to be constant. However, we find that a health shock increases individual risk aversion. The finding is robust to a series of sensitivity analyses and persists for at least four years after the shock. Income changes do not seem to be the driving mechanism. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Shock in the emergency department

    Holler, Jon Gitz; Henriksen, Daniel Pilsgaard; Mikkelsen, Søren

    2016-01-01

    BACKGROUND: The knowledge of the frequency and associated mortality of shock in the emergency department (ED) is limited. The aim of this study was to describe the incidence, all-cause mortality and factors associated with death among patients suffering shock in the ED. METHODS: Population...... failures. Outcomes were annual incidence per 100,000 person-years at risk (pyar), all-cause mortality at 0-7, and 8-90 days and risk factors associated with death. RESULTS: We identified 1646 of 438,191 (0.4 %) ED patients with shock at arrival. Incidence of shock increased from 53.8 to 80.6 cases per 100...

  10. Shock compression of diamond crystal

    Kondo, Ken-ichi; Ahrens, Thomas J.

    1983-01-01

    Two shock wave experiments employing inclined mirrors have been carried out to determine the Hugoniot elastic limit (HEL), final shock state at 191 and 217 GPa, and the post-shock state of diamond crystal, which is shock-compressed along the intermediate direction between the and crystallographic axes. The HEL wave has a velocity of 19.9 ± 0.3 mm/µsec and an amplitude of 63 ± 28 GPa. An alternate interpretation of the inclined wedge mirror streak record suggests a ramp precursor wave and th...

  11. A Shocking Solar Nebula?

    Liffman, Kurt

    2009-01-01

    It has been suggested that shock waves in the solar nebula formed the high temperature materials observed in meteorites and comets. It is shown that the temperatures at the inner rim of the solar nebula could have been high enough over a sufficient length of time to produce chondrules, CAIs, refractory dust grains and other high-temperature materials observed in comets and meteorites. The solar bipolar jet flow may have produced an enrichment of 16O in the solar nebula over time and the chond...

  12. Myths of "shock therapy".

    Fink, M

    1977-09-01

    The author discusses the myths of the ECT process--that shock and the convulsion are essential, memory loss and brain damage are inescapable, and little is known of the process--and assesses the fallacies in these ideas. Present views of the ECT process suggest that its mode of action in depression may best be described as a prolonged form of diencephalic stimulation, particularly useful to affect the hypothalamic dysfunctions that characterize depressive illness. The author emphasizes the need for further study of this treatment modality and for self-regulation by the profession.

  13. Recording visual evoked potentials and auditory evoked P300 at 9.4T static magnetic field.

    Arrubla, Jorge; Neuner, Irene; Hahn, David; Boers, Frank; Shah, N Jon

    2013-01-01

    Simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has shown a number of advantages that make this multimodal technique superior to fMRI alone. The feasibility of recording EEG at ultra-high static magnetic field up to 9.4 T was recently demonstrated and promises to be implemented soon in fMRI studies at ultra high magnetic fields. Recording visual evoked potentials are expected to be amongst the most simple for simultaneous EEG/fMRI at ultra-high magnetic field due to the easy assessment of the visual cortex. Auditory evoked P300 measurements are of interest since it is believed that they represent the earliest stage of cognitive processing. In this study, we investigate the feasibility of recording visual evoked potentials and auditory evoked P300 in a 9.4 T static magnetic field. For this purpose, EEG data were recorded from 26 healthy volunteers inside a 9.4 T MR scanner using a 32-channel MR compatible EEG system. Visual stimulation and auditory oddball paradigm were presented in order to elicit evoked related potentials (ERP). Recordings made outside the scanner were performed using the same stimuli and EEG system for comparison purposes. We were able to retrieve visual P100 and auditory P300 evoked potentials at 9.4 T static magnetic field after correction of the ballistocardiogram artefact using independent component analysis. The latencies of the ERPs recorded at 9.4 T were not different from those recorded at 0 T. The amplitudes of ERPs were higher at 9.4 T when compared to recordings at 0 T. Nevertheless, it seems that the increased amplitudes of the ERPs are due to the effect of the ultra-high field on the EEG recording system rather than alteration in the intrinsic processes that generate the electrophysiological responses.

  14. Gravitational shock waves and extreme magnetomaterial shock waves

    Lichnerowicz, Andre.

    1975-01-01

    Within an astrophysical context corresponding to high densities, a self-gravitating model is studied, which is the set of an extreme material medium of infinite conductivity and of a magnetic field. Corresponding shock waves generate necessarily, in general, gravitational shock waves [fr

  15. Shock Producers and Shock Absorbers in the Crisis

    Sinn, Hans-Werner

    2009-01-01

    It is not surprising that the U.S. has been by far the world’s largest shock producer in this crisis. The big shock absorbers on the other hand were Japan, Russia and Germany, whose exports shrank more than their imports.

  16. Simulations of Converging Shock Collisions for Shock Ignition

    Sauppe, Joshua; Dodd, Evan; Loomis, Eric

    2016-10-01

    Shock ignition (SI) has been proposed as an alternative to achieving high gain in inertial confinement fusion (ICF) targets. A central hot spot below the ignition threshold is created by an initial compression pulse, and a second laser pulse drives a strong converging shock into the fuel. The collision between the rebounding shock from the compression pulse and the converging shock results in amplification of the converging shock and increases the hot spot pressure above the ignition threshold. We investigate shock collision in SI drive schemes for cylindrical targets with a polystyrene foam interior using radiation-hydrodynamics simulations with the RAGE code. The configuration is similar to previous targets fielded on the Omega laser. The CH interior results in a lower convergence ratio and the cylindrical geometry facilitates visualization of the shock transit using an axial X-ray backlighter, both of which are important for comparison to potential experimental measurements. One-dimensional simulations are used to determine shock timing, and the effects of low mode asymmetries in 2D computations are also quantified. LA-UR-16-24773.

  17. 30th International Symposium on Shock Waves

    Sadot, Oren; Igra, Ozer

    2017-01-01

    These proceedings collect the papers presented at the 30th International Symposium on Shock Waves (ISSW30), which was held in Tel-Aviv Israel from July 19 to July 24, 2015. The Symposium was organized by Ortra Ltd. The ISSW30 focused on the state of knowledge of the following areas: Nozzle Flow, Supersonic and Hypersonic Flows with Shocks, Supersonic Jets, Chemical Kinetics, Chemical Reacting Flows, Detonation, Combustion, Ignition, Shock Wave Reflection and Interaction, Shock Wave Interaction with Obstacles, Shock Wave Interaction with Porous Media, Shock Wave Interaction with Granular Media, Shock Wave Interaction with Dusty Media, Plasma, Magnetohyrdrodynamics, Re-entry to Earth Atmosphere, Shock Waves in Rarefied Gases, Shock Waves in Condensed Matter (Solids and Liquids), Shock Waves in Dense Gases, Shock Wave Focusing, Richtmyer-Meshkov Instability, Shock Boundary Layer Interaction, Multiphase Flow, Blast Waves, Facilities, Flow Visualization, and Numerical Methods. The two volumes serve as a reference ...

  18. High frequency oscillations evoked by peripheral magnetic stimulation.

    Biller, S; Simon, L; Fiedler, P; Strohmeier, D; Haueisen, J

    2011-01-01

    The analysis of somatosensory evoked potentials (SEP) and / or fields (SEF) is a well-established and important tool for investigating the functioning of the peripheral and central human nervous system. A standard technique to evoke SEPs / SEFs is the stimulation of the median nerve by using a bipolar electrical stimulus. We aim at an alternative stimulation technique enabling stimulation of deep nerve structures while reducing patient stress and error susceptibility. In the current study, we apply a commercial transcranial magnetic stimulation system for peripheral magnetic stimulation of the median nerve. We compare the results of simultaneously recorded EEG signals to prove applicability of our technique to evoke SEPs including low frequency components (LFC) as well as high frequency oscillations (HFO). Therefore, we compare amplitude, latency and time-frequency characteristics of the SEP of 14 healthy volunteers after electric and magnetic stimulation. Both low frequency components and high frequency oscillations were detected. The HFOs were superimposed onto the primary cortical response N20. Statistical analysis revealed significantly lower amplitudes and increased latencies for LFC and HFO components after magnetic stimulation. The differences indicate the inability of magnetic stimulation to elicit supramaximal responses. A psycho-perceptual evaluation showed that magnetic stimulation was less unpleasant for 12 out of the 14 volunteers. In conclusion, we showed that LFC and HFO components related to median nerve stimulation can be evoked by peripheral magnetic stimulation.

  19. Evoked responses to sinusoidally modulated sound in unanaesthetized dogs

    Tielen, A.M.; Kamp, A.; Lopes da Silva, F.H.; Reneau, J.P.; Storm van Leeuwen, W.

    1. 1. Responses evoked by sinusoidally amplitude-modulated sound in unanaesthetized dogs have been recorded from inferior colliculus and from auditory cortex structures by means of chronically indwelling stainless steel wire electrodes. 2. 2. Harmonic analysis of the average responses demonstrated

  20. Prior Expectations Evoke Stimulus Templates in the Primary Visual Cortex

    Kok, P.; Failing, F.M.; de Lange, F.P.

    2014-01-01

    Exposure to rhythmic stimulation results in facilitated responses to events that appear in-phase with the rhythm and modulation of anticipatory and target-evoked brain activity, presumably reflecting "exogenous," unintentional temporal expectations. However, the extent to which this effect is

  1. The role of Magnetic Resonance Imaging and Visual Evoked ...

    Introduction: To report our experience in management of patients with optic neuritis. The effects of brain magnetic resonance imaging and visual evoked potential on management were investigated. Methods: This is a four years clinical trial that included patients presenting with first attack of optic neuritis older than 16 years ...

  2. Molecular diagnostics of interstellar shocks

    Hartquist, T.W.; Oppenheimer, M.; Dalgarno, A.

    1980-01-01

    The chemistry of molecules in shocked regions of the interstellar gas is considered and calculations are carried out for a region subjected to a shock at a velocity of 8 km s -1 Substantial enhancements are predicted in the concentrations of the molecules H 2 S, SO, and SiO compared to those anticipated in cold interstellar clouds

  3. Molecular diagnostics of interstellar shocks

    Hartquist, T. W.; Dalgarno, A.; Oppenheimer, M.

    1980-02-01

    The chemistry of molecules in shocked regions of the interstellar gas is considered and calculations are carried out for a region subjected to a shock at a velocity of 8 km/sec. Substantial enhancements are predicted in the concentrations of the molecules H2S, SO, and SiO compared to those anticipated in cold interstellar clouds.

  4. How Culture Shock Affects Communication.

    Barna, LaRay M.

    The paper defines the term "culture shock" and discusses the changes that this state can make in a person's behavior. Culture shock refers to the emotional and physiological reaction of high activation that is brought about by sudden immersion in a new culture. Because one's own culture shields one from the unknown and reduces the need to make…

  5. Molecular diagnostics of interstellar shocks

    Hartquist, T. W.; Dalgarno, A.; Oppenheimer, M.

    1980-01-01

    The chemistry of molecules in shocked regions of the interstellar gas is considered and calculations are carried out for a region subjected to a shock at a velocity of 8 km/sec. Substantial enhancements are predicted in the concentrations of the molecules H2S, SO, and SiO compared to those anticipated in cold interstellar clouds.

  6. Shock wave treatment in medicine

    Home; Journals; Journal of Biosciences; Volume 30; Issue 2 ... In the present paper we discuss the basic theory and application of shock waves and its history in medicine. The idea behind using shock wave therapy for orthopedic diseases is the stimulation of healing in tendons, surrounding tissue and bones. This is a ...

  7. Shock wave treatment in medicine

    Unknown

    to open surgery, the cost of the ESWT is very reasonable. But nevertheless it is necessary to improve the basic un ... In second group, shock waves are used to measure distances because of the low energy loss over large distances ... pared to a piezoelectric hydrophone. The rise time of an electrohydraulic generated shock ...

  8. Numerical modeling of slow shocks

    Winske, D.

    1987-01-01

    This paper reviews previous attempt and the present status of efforts to understand the structure of slow shocks by means of time dependent numerical calculations. Studies carried out using MHD or hybrid-kinetic codes have demonstrated qualitative agreement with theory. A number of unresolved issues related to hybrid simulations of the internal shock structure are discussed in some detail. 43 refs., 8 figs

  9. Dynamic shock wave: hammer blow

    Lackme, Claude

    1978-01-01

    The general properties of shocks, their generation and the conditions of reflexion to an interface are dealt with in turn. By then applying these concepts to a liquid column and its environment (wall, free area, closing devices) the hammer blow is presented as being a relatively weak shock [fr

  10. Slow shocks and their transition to fast shocks in the inner solar wind

    Wang, Y.C.

    1987-01-01

    The jump conditions of MHD shocks may be directly calculated as functions of three upstream conditions: the shock Alfven number based on the normal component of the relative shock speed, the shock angle, and the plasma β value. The shock Alfven number is less than 1 for a slow shock and greater than 1 for a fast shock. A traveling, forward shock can be a slow shock in coronal space, where the Alfven speed is of the order of 1000 km/s. The surface of a forward slow shock has a bow-shaped geometry with its nose facing toward the sun. The decrease in the Alfven speed at increasing heliocentric distance causes the shock Alfven number of a forward slow shock to become greater than 1, and the shock eventually evolves from a slow shock into a fast shock. During the transition the shock system consists of a slow shock, a fast shock, and a rotational discontinuity. They intersect along a closed transition line. As the system moves outward from the sun, the area enclosed by the transition line expands, the fast shock grows stronger, and the slow shock becomes weaker. Eventually, the slow shock diminishes, and the entire shock system evolves into a forward fast shock. copyrightAmerican Geophysical Union 1987

  11. Visual evoked potentials in patients after methanol poisoning.

    Urban, Pavel; Zakharov, Sergey; Diblík, Pavel; Pelclová, Daniela; Ridzoň, Petr

    2016-01-01

    We report the results of the visual evoked potentials (VEP) examination in patients after severe poisoning by methanol. The group of 47 patients (38 males and 9 females) was assembled out of persons who survived an outbreak of poisoning by the methanol adulterated alcohol beverages, which happened in the Czech Republic in 2012-2013. The visual evoked potentials examination was performed using monocular checkerboard pattern-reversal stimulation. Two criteria of abnormality were chosen: missing evoked response, and wave P1 latency > 117 ms. Non-parametric statistical methods (median, range, and the median test) were used to analyze factors influencing the VEP abnormality. The visual evoked potential was abnormal in 20 patients (43%), 5 of them had normal visual acuity on the Snellen chart. The VEP abnormality did not correlate significantly with initial serum concentrations of methanol, formic acid or lactate; however, it showed statistically significant inverse relation to the initial serum pH: the subgroup with the abnormal VEP had significantly lower median pH in comparison with the subgroup with the normal VEP (7.16 vs. 7.34, p = 0.04). The abnormality was not related to chronic alcohol abuse. The visual evoked potentials examination appeared sensitive enough to detected even subclinical impairment of the optic system. Metabolic acidosis is likely to be the key factor related to the development of visual damage induced by methanol. The examination performed with a delay of 1-9 months after the poisoning documented the situation relatively early after the event. It is considered as a baseline for the planned long-term follow-up of the patients, which will make it possible to assess the dynamics of the observed changes, their reversibility, and the occurrence of potential late sequelae. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  12. Shocking matter to extreme conditions

    Gupta, Y.M.; Sharma, S.M.

    1997-01-01

    A good understanding of the thermodynamic response of matter at high compression and high energy densities is important to several areas of physics. Shock-wave experiments are uniquely suited for obtaining data at extreme conditions, and a shock-compressed matter can be viewed as a condensed system with or without dissociation or as a strongly coupled plasma. This article reviews work by Da Silva et al. in which irradiances ranging from 5x10 superscript 12 to 2x10 superscript 14 W/cm 2 were used to generate 8- to 10-ns square pulses in liquid deuterium. The authors demonstrated negligible pre-heating of the sample, steady propagation of the shock wave, and direct determination of the shock wave velocity along with particle velocity and density in the shocked state. Da Silva et al. results are compared with models and other experimental information, and the usefulness of the data in other areas is assessed. 11 refs., 1 fig

  13. Electron transport and shock ignition

    Bell, A R; Tzoufras, M, E-mail: t.bell1@physics.ox.ac.uk [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom)

    2011-04-15

    Inertial fusion energy (IFE) offers one possible route to commercial energy generation. In the proposed 'shock ignition' route to fusion, the target is compressed at a relatively low temperature and then ignited using high intensity laser irradiation which drives a strong converging shock into the centre of the fuel. With a series of idealized calculations we analyse the electron transport of energy into the target, which produces the pressure responsible for driving the shock. We show that transport in shock ignition lies near the boundary between ablative and heat front regimes. Moreover, simulations indicate that non-local effects are significant in the heat front regime and might lead to increased efficiency by driving the shock more effectively and reducing heat losses to the plasma corona.

  14. Oscillating nonlinear acoustic shock waves

    Gaididei, Yuri; Rasmussen, Anders Rønne; Christiansen, Peter Leth

    2016-01-01

    We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show that at resona......We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show...... polynomial in the space and time variables, we find analytical approximations to the observed single shock waves in an infinitely long tube. Using perturbation theory for the driven acoustic system approximative analytical solutions for the off resonant case are determined....

  15. Shock waves & explosions

    Sachdev, PL

    2004-01-01

    Understanding the causes and effects of explosions is important to experts in a broad range of disciplines, including the military, industrial and environmental research, aeronautic engineering, and applied mathematics. Offering an introductory review of historic research, Shock Waves and Explosions brings analytic and computational methods to a wide audience in a clear and thorough way. Beginning with an overview of the research on combustion and gas dynamics in the 1970s and 1980s, the author brings you up to date by covering modeling techniques and asymptotic and perturbative methods and ending with a chapter on computational methods.Most of the book deals with the mathematical analysis of explosions, but computational results are also included wherever they are available. Historical perspectives are provided on the advent of nonlinear science, as well as on the mathematical study of the blast wave phenomenon, both when visualized as a point explosion and when simulated as the expansion of a high-pressure ...

  16. Analysis of shock implosion

    Mishkin, E.A.; Alejaldre, C. (Polytechnic Inst. of New York, Brooklyn (USA))

    1984-06-01

    An imploding shock wave, coming from infinity, moves through an ideal gas with the adiabatic constant ..gamma... To define a single-valued self-similar coefficient over the whole classical interval 1<..gamma..

  17. Does extracorporeal shock wave lithotripsy cause hearing impairment?

    Tuncer, Murat; Erdogan, Banu A; Yazici, Ozgur; Sahin, Cahit; Altin, Gokhan; Faydaci, Gokhan; Eryildirim, Bilal; Sarica, Kemal

    2014-07-01

    To evaluate the possible effects of extracorporeal shock wave lithotripsy (ESWL) on the hearing status of the patients in this prospective controlled study. A total of 40 patients with normal hearing function were included to the study. We had 20 patients each in the study group and control group. The treatment parameters were standardized in all 3 sessions in which a total of 3000 shock waves with a rate of 90/min along with a total energy value of 126 J at the fourth energy level have been applied (Dornier Compact Sigma, Medtech, Germany). In addition to the testing of hearing functions and possible cochlear impairment by Transient Evoked Otoacoustic Emissions test at 1.0, 1.4, 2.0, 2.8, and 4.0 kHz frequencies, complications such as ear pain, tinnitus, and hearing loss have been well evaluated in each patient before the procedure and 2 hours and 1 month after the completion of the third session of ESWL in the study group. The same evaluation procedures were performed before the study and after 7-weeks in the control group. Regarding Transient Evoked Otoacoustic Emissions data obtained in study group and control group patients, there was no significant alteration in values obtained after ESWL when compared with the values before the procedure. A well-planned ESWL procedure is a safe and effective treatment in urinary stones and causes no detectable harmful effect on the hearing function of treated patients. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. The cosmic-ray shock structure problem for relativistic shocks

    Webb, G. M.

    1985-01-01

    The time asymptotic behaviour of a relativistic (parallel) shock wave significantly modified by the diffusive acceleration of cosmic-rays is investigated by means of relativistic hydrodynamical equations for both the cosmic-rays and thermal gas. The form of the shock structure equation and the dispersion relation for both long and short wavelength waves in the system are obtained. The dependence of the shock acceleration efficiency on the upstream fluid spped, long wavelength Mach number and the ratio N = P sub co/cP sub co+P sub go)(Psub co and P sub go are the upstream cosmic-ray and thermal gas pressures respectively) are studied.

  19. Cosmic-ray shock acceleration in oblique MHD shocks

    Webb, G. M.; Drury, L. OC.; Volk, H. J.

    1986-01-01

    A one-dimensional, steady-state hydrodynamical model of cosmic-ray acceleration at oblique MHD shocks is presented. Upstream of the shock the incoming thermal plasma is subject to the adverse pressure gradient of the accelerated particles, the J x B force, as well as the thermal gas pressure gradient. The efficiency of the acceleration of cosmic-rays at the shock as a function of the upstream magnetic field obliquity and upstream plasma beta is investigated. Astrophysical applications of the results are briefly discussed.

  20. Chondrule destruction in nebular shocks

    Jacquet, Emmanuel; Thompson, Christopher, E-mail: ejacquet@mnhn.fr [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St George Street, Toronto, ON M5S 3H8 (Canada)

    2014-12-10

    Chondrules are millimeter-sized silicate spherules ubiquitous in primitive meteorites, but whose origin remains mysterious. One of the main proposed mechanisms for producing them is melting of solids in shock waves in the gaseous protoplanetary disk. However, evidence is mounting that chondrule-forming regions were enriched in solids well above solar abundances. Given the high velocities involved in shock models, destructive collisions would be expected between differently sized grains after passage of the shock front as a result of differential drag. We investigate the probability and outcome of collisions of particles behind a one-dimensional shock using analytic methods as well as a full integration of the coupled mass, momentum, energy, and radiation equations. Destruction of protochondrules seems unavoidable for solid/gas ratios ε ≳ 0.1, and possibly even for solar abundances because of 'sandblasting' by finer dust. A flow with ε ≳ 10 requires much smaller shock velocities (∼2 versus 8 km s{sup –1}) in order to achieve chondrule-melting temperatures, and radiation trapping allows slow cooling of the shocked fragments. Initial destruction would still be extensive; although re-assembly of millimeter-sized particles would naturally occur by grain sticking afterward, the compositional heterogeneity of chondrules may be difficult to reproduce. We finally note that solids passing through small-scale bow shocks around few kilometer-sized planetesimals might experience partial melting and yet escape fragmentation.

  1. An inventory and update of jealousy-evoking partner behaviours in modern society.

    Dijkstra, Pieternel; Barelds, Dick P. H.; Groothof, Hinke A. K.

    2010-01-01

    The goal of the present study was to identify the most important jealousy-evoking partner behaviours and to examine the extent to which these behaviours evoke jealousy. Based on the literature, a questionnaire was constructed containing 42 jealousy-evoking partner behaviours, including a partner's

  2. Simulation of mechanical shock environments

    Lalanne, Christian.

    1975-07-01

    Shocks can produce a severe mechanical environment which must be taken into account when designing and developing new equipments. After some mathematical (Laplace and Fourier transforms) and mechanical recalls (response of a one degree freedom system to a sinusoidal excitation), different analysis methods are compared, these methods being the most used now to compare relative severities of tests and establish specifications. A few chapter deal with the different properties of simple, easy to produce, shock shapes. Then some now-in-use programmators or shock-machines specifications are shown. A final chapter concerns acceleration transducers [fr

  3. Particle acceleration in modified shocks

    Drury, L.O'C.; Axford, W.I.; Summers, D.

    1982-01-01

    Efficient particle acceleration in shocks must modify the shock structure with consequent changes in the particle acceleration. This effect is studied and analytic solutions are found describing the diffusive acceleration of particles with momentum independent diffusion coefficients in hyperbolic tangent type velocity transitions. If the input particle spectrum is a delta function, the shock smoothing replaces the truncated power-law downstream particle spectrum by a more complicated form, but one which has a power-law tail at high momenta. For a cold plasma this solution can be made completely self-consistent. Some problems associated with momentum dependent diffusion coefficients are discussed. (author)

  4. INTERFERENCE OF COUNTERPROPAGATING SHOCK WAVES

    P. V. Bulat

    2015-03-01

    Full Text Available The subject of study. We examined the interaction of counterpropagating shock waves. The necessity of counterpropagating shock waves studying occurs at designing of high Mach number modern internal compression air intakes, Ramjets with subsonic and supersonic combustion, in asymmetrical supersonic nozzles and in some other cases. In a sense, this problem is a generalization of the case of an oblique shock reflection from the wall or from the plane of symmetry. With the renewed vigor, the interest to this problem emerged at the end of the 90s. This was due to the start of the programs for flight study at hypersonic speeds. The first experiments performed with air intakes, which realized the interaction of counterpropagating shock waves have shown that the change in flow velocity is accompanied by abrupt alteration of shock-wave structure, the occurrence of nonstationary and oscillatory phenomena. With an increase of flow velocity these phenomena undesirable for aircraft structure became more marked. The reason is that there are two fundamentally different modes of interaction of counterpropagating shock waves: a four-wave regular and a five-wave irregular. The transition from one mode to another can be nonstationary abrupt or gradual, it can also be accompanied by hysteresis. Main results. Criteria for the transition from regular reflection of counterpropagating shock waves to irregular are described: the criterion of von Neumann and the stationary Mach configuration criterion. We described areas in which the transition from one reflection type to another is possible only in abrupt way, as well as areas of possible gradual transition. Intensity dependences of the reflected shock waves from the intensity of interacting counterpropagating shocks were given. Qualitative pictures of shock-wave structures arising from the interaction of counterpropagating shock waves were shown. Calculation results of the intensity of outgoing gas

  5. Particle acceleration in modified shocks

    Drury, L.O' C. (Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany, F.R.)); Axford, W.I. (Max-Planck-Institut fuer Aeronomie, Katlenburg-Lindau (Germany, F.R.)); Summers, D. (Memorial Univ. of Newfoundland, St. John' s (Canada))

    1982-03-01

    Efficient particle acceleration in shocks must modify the shock structure with consequent changes in the particle acceleration. This effect is studied and analytic solutions are found describing the diffusive acceleration of particles with momentum independent diffusion coefficients in hyperbolic tangent type velocity transitions. If the input particle spectrum is a delta function, the shock smoothing replaces the truncated power-law downstream particle spectrum by a more complicated form, but one which has a power-law tail at high momenta. For a cold plasma this solution can be made completely self-consistent. Some problems associated with momentum dependent diffusion coefficients are discussed.

  6. Shocks in the Early Universe.

    Pen, Ue-Li; Turok, Neil

    2016-09-23

    We point out a surprising consequence of the usually assumed initial conditions for cosmological perturbations. Namely, a spectrum of Gaussian, linear, adiabatic, scalar, growing mode perturbations not only creates acoustic oscillations of the kind observed on very large scales today, it also leads to the production of shocks in the radiation fluid of the very early Universe. Shocks cause departures from local thermal equilibrium as well as create vorticity and gravitational waves. For a scale-invariant spectrum and standard model physics, shocks form for temperatures 1  GeVUniverse as early as 10^{-30}  sec after the big bang.

  7. Abdominal acupuncture reduces laser-evoked potentials in healthy subjects

    Pazzaglia, C.; Liguori, S.; Minciotti, I.

    2015-01-01

    Objective: Acupuncture is known to reduce clinical pain, although the exact mechanism is unknown. The aim of the current study was to investigate the effect of acupuncture on laser-evoked potential amplitudes and laser pain perception. Methods: In order to evaluate whether abdominal acupuncture...... is able to modify pain perception, 10 healthy subjects underwent a protocol in which laser-evoked potentials (LEPs) and laser pain perception were collected before the test (baseline), during abdominal acupuncture, and 15. min after needle removal. The same subjects also underwent a similar protocol...... in which, however, sham acupuncture without any needle penetration was used. Results: During real acupuncture, both N1 and N2/P2 amplitudes were reduced, as compared to baseline (p . < 0.01). The reduction lasted up to 15. min after needle removal. Furthermore, laser pain perception was reduced during...

  8. Automatic classification of visual evoked potentials based on wavelet decomposition

    Stasiakiewicz, Paweł; Dobrowolski, Andrzej P.; Tomczykiewicz, Kazimierz

    2017-04-01

    Diagnosis of part of the visual system, that is responsible for conducting compound action potential, is generally based on visual evoked potentials generated as a result of stimulation of the eye by external light source. The condition of patient's visual path is assessed by set of parameters that describe the time domain characteristic extremes called waves. The decision process is compound therefore diagnosis significantly depends on experience of a doctor. The authors developed a procedure - based on wavelet decomposition and linear discriminant analysis - that ensures automatic classification of visual evoked potentials. The algorithm enables to assign individual case to normal or pathological class. The proposed classifier has a 96,4% sensitivity at 10,4% probability of false alarm in a group of 220 cases and area under curve ROC equals to 0,96 which, from the medical point of view, is a very good result.

  9. Single-sweep spectral analysis of contact heat evoked potentials

    Hansen, Tine M; Graversen, Carina; Frøkjaer, Jens B

    2015-01-01

    AIMS: The cortical response to nociceptive thermal stimuli recorded as contact heat evoked potentials (CHEPs) may be altered by morphine. However, previous studies have averaged CHEPs over multiple stimuli, which are confounded by jitter between sweeps. Thus, the aim was to assess single-sweep ch......AIMS: The cortical response to nociceptive thermal stimuli recorded as contact heat evoked potentials (CHEPs) may be altered by morphine. However, previous studies have averaged CHEPs over multiple stimuli, which are confounded by jitter between sweeps. Thus, the aim was to assess single...... by 13% (P = 0.04) and 9% (P = 0.007), while the beta and gamma bands were increased by 10% (P = 0.006) and 24% (P = 0.04). CONCLUSION: The decreases in the delta and theta band are suggested to represent a decrease in the pain specific morphology of the CHEPs, which indicates a diminished pain response...

  10. Shock parameter calculations at weak interplanetary shock waves

    J. M. Gloag

    2005-02-01

    Full Text Available A large set of interplanetary shock waves observed using the Ulysses spacecraft is analysed in order to determine their local parameters. For the first time a detailed analysis is extended to the thermodynamic properties of a large number of events. The intention is to relate the shock parameters to the requirements set by MHD shock theory. A uniform approach is adopted in the selection of up and downstream regions for this analysis and applied to all the shock waves. Initially, the general case of a 3 component adiabatic plasma is considered. However, the calculation of magnetosonic and Alfvénic Mach numbers and the ratio of downstream to upstream entropy produce some unexpected results. In some cases there is no clear increase in entropy across the shock and also the magnetosonic Mach number can be less than 1. It is found that a more discerning use of data along with an empirical value for the polytropic index can raise the distribution of downstream to upstream entropy ratios to a more acceptable level. However, it is also realised that many of these shocks are at the very weakest end of the spectrum and associated phenomena may also contribute to the explanation of these results.

  11. Quasilinear simulations of interplanetary shocks and Earth's bow shock

    Afanasiev, Alexandr; Battarbee, Markus; Ganse, Urs; Vainio, Rami; Palmroth, Minna; Pfau-Kempf, Yann; Hoilijoki, Sanni; von Alfthan, Sebastian

    2016-04-01

    We have developed a new self-consistent Monte Carlo simulation model for particle acceleration in shocks. The model includes a prescribed large-scale magnetic field and plasma density, temperature and velocity profiles and a self-consistently computed incompressible ULF foreshock under the quasilinear approximation. Unlike previous analytical treatments, our model is time dependent and takes full account of the anisotropic particle distributions and scattering in the wave-particle interaction process. We apply the model to the problem of particle acceleration at traveling interplanetary (IP) shocks and Earth's bow shock and compare the results with hybrid-Vlasov simulations and spacecraft observations. A qualitative agreement in terms of spectral shape of the magnetic fluctuations and the polarization of the unstable mode is found between the models and the observations. We will quantify the differences of the models and explore the region of validity of the quasilinear approach in terms of shock parameters. We will also compare the modeled IP shocks and the bow shock, identifying the similarities and differences in the spectrum of accelerated particles and waves in these scenarios. The work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324 (HESPERIA). The Academy of Finland is thanked for financial support. We acknowledge the computational resources provided by CSC - IT Centre for Science Ltd., Espoo.

  12. Diaphragmless shock wave generators for industrial applications of shock waves

    Hariharan, M. S.; Janardhanraj, S.; Saravanan, S.; Jagadeesh, G.

    2011-06-01

    The prime focus of this study is to design a 50 mm internal diameter diaphragmless shock tube that can be used in an industrial facility for repeated loading of shock waves. The instantaneous rise in pressure and temperature of a medium can be used in a variety of industrial applications. We designed, fabricated and tested three different shock wave generators of which one system employs a highly elastic rubber membrane and the other systems use a fast acting pneumatic valve instead of conventional metal diaphragms. The valve opening speed is obtained with the help of a high speed camera. For shock generation systems with a pneumatic cylinder, it ranges from 0.325 to 1.15 m/s while it is around 8.3 m/s for the rubber membrane. Experiments are conducted using the three diaphragmless systems and the results obtained are analyzed carefully to obtain a relation between the opening speed of the valve and the amount of gas that is actually utilized in the generation of the shock wave for each system. The rubber membrane is not suitable for industrial applications because it needs to be replaced regularly and cannot withstand high driver pressures. The maximum shock Mach number obtained using the new diaphragmless system that uses the pneumatic valve is 2.125 ± 0.2%. This system shows much promise for automation in an industrial environment.

  13. Pharmacology of Bradykinin-Evoked Coughing in Guinea Pigs

    Hewitt, Matthew M.; Adams, Gregory; Mazzone, Stuart B.; Mori, Nanako; Yu, Li; Canning, Brendan J.

    2016-01-01

    Bradykinin has been implicated as a mediator of the acute pathophysiological and inflammatory consequences of respiratory tract infections and in exacerbations of chronic diseases such as asthma. Bradykinin may also be a trigger for the coughing associated with these and other conditions. We have thus set out to evaluate the pharmacology of bradykinin-evoked coughing in guinea pigs. When inhaled, bradykinin induced paroxysmal coughing that was abolished by the bradykinin B2 receptor antagonis...

  14. Pharmacology of Bradykinin-Evoked Coughing in Guinea Pigs.

    Hewitt, Matthew M; Adams, Gregory; Mazzone, Stuart B; Mori, Nanako; Yu, Li; Canning, Brendan J

    2016-06-01

    Bradykinin has been implicated as a mediator of the acute pathophysiological and inflammatory consequences of respiratory tract infections and in exacerbations of chronic diseases such as asthma. Bradykinin may also be a trigger for the coughing associated with these and other conditions. We have thus set out to evaluate the pharmacology of bradykinin-evoked coughing in guinea pigs. When inhaled, bradykinin induced paroxysmal coughing that was abolished by the bradykinin B2 receptor antagonist HOE 140. These cough responses rapidly desensitized, consistent with reports of B2 receptor desensitization. Bradykinin-evoked cough was potentiated by inhibition of both neutral endopeptidase and angiotensin-converting enzyme (with thiorphan and captopril, respectively), but was largely unaffected by muscarinic or thromboxane receptor blockade (atropine and ICI 192605), cyclooxygenase, or nitric oxide synthase inhibition (meclofenamic acid and N(G)-nitro-L-arginine). Calcium influx studies in bronchopulmonary vagal afferent neurons dissociated from vagal sensory ganglia indicated that the tachykinin-containing C-fibers arising from the jugular ganglia mediate bradykinin-evoked coughing. Also implicating the jugular C-fibers was the observation that simultaneous blockade of neurokinin2 (NK2; SR48968) and NK3 (SR142801 or SB223412) receptors nearly abolished the bradykinin-evoked cough responses. The data suggest that bradykinin induces coughing in guinea pigs by activating B2 receptors on bronchopulmonary C-fibers. We speculate that therapeutics targeting the actions of bradykinin may prove useful in the treatment of cough. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

  15. Temporal suppression and augmentation of click-evoked otoacoustic emissions

    Verhulst, Sarah; Harte, James; Dau, Torsten

    2008-01-01

    This study investigates temporal suppression of click-evoked otoacoustic emissions (CEOAEs), occurring when a suppressor-click is presented close in time to a test-click (e.g. 0-8ms). Various temporal suppression methods for examining temporal changes in cochlear compression were evaluated and me...... under test. Temporal suppression was shown to be comparable for CEOAEs and SSOAEs, indicating similar underlying cochlear nonlinear mechanisms. This study contributes to a better understanding of the temporal properties of cochlear dynamics....

  16. Sympathetic skin response evoked by laser skin stimulation

    Rossi, P.; Truini, A.; Serrao, M.; Iannetti, G. D.; Parisi, L.; Pozzessere, G.; Cruccu, G.

    2002-01-01

    The objective of this study was to evoke sympathetic skin responses (SSRs) in healthy subjects using laser stimulation and to compare these responses with those induced by conventional electrical stimuli. Twenty healthy subjects were investigated. SSRs were obtained using electrical and laser stimuli delivered to the wrist controlateral to the recording site. The sympathetic sudomotor conduction velocity (SSFCV) was measured in 8 subjects by simultaneously recording the SSR from the hand and ...

  17. Brain stem auditory evoked responses in chronic alcoholics.

    Chan, Y W; McLeod, J G; Tuck, R R; Feary, P A

    1985-01-01

    Brain stem auditory evoked responses (BAERs) were performed on 25 alcoholic patients with Wernicke-Korsakoff syndrome, 56 alcoholic patients without Wernicke-Korsakoff syndrome, 24 of whom had cerebellar ataxia, and 37 control subjects. Abnormal BAERs were found in 48% of patients with Wernicke-Korsakoff syndrome, in 25% of alcoholic patients without Wernicke-Korsakoff syndrome but with cerebellar ataxia, and in 13% of alcoholic patients without Wernicke-Korsakoff syndrome or ataxia. The mean...

  18. Shock wave dynamics derivatives and related topics

    Emanuel, George

    2012-01-01

    "...this monograph develops an esoteric niche within shock wave theory. …treats shock waves from an analytical approach assuming perfect gas. Emanuel has made significant contributions to the theory of shock waves and has selected a number of topics that reflect those contributions."-Shock Waves, 2013.

  19. Comparison of the cardiovascular effects of meptazinol and naloxone following haemorrhagic shock in rats and cats.

    Chance, E.; Paciorek, P. M.; Todd, M. H.; Waterfall, J. F.

    1985-01-01

    The cardiovascular effects of the opioid mixed agonist-antagonist, meptazinol, and the opioid antagonist, naloxone, have been evaluated in conscious rats, anaesthetized rats and anaesthetized cats following the induction of haemorrhagic shock. The mean arterial pressure of conscious rats decreased by 17-29 mmHg following a haemorrhage of 20% of blood volume. Meptazinol (17 mg kg-1, i.m.) administered after haemorrhage evoked a rapid and sustained increase in mean arterial pressure to pre-haemorrhage levels. Naloxone (10 mg kg-1, i.v.) also increased mean arterial pressure to a level significantly higher than post-haemorrhage values. Neither haemorrhage nor subsequent drug treatments evoked significant changes in the heart rates of conscious rats. In anaesthetized rats, 20% haemorrhage evoked decreases in mean arterial pressure, heart rate and cardiac output. Blood flow to the heart, skin, skeletal muscle, kidneys, spleen and liver (arterial) was decreased. Meptazinol and naloxone increased blood pressure and total peripheral resistance, but did not significantly alter heart rate or cardiac output. Hepatic arterial flow decreased further in both drug and vehicle treated groups. In addition meptazinol slightly reduced skeletal muscle flow. In anaesthetized cats 40% haemorrhage decreased mean arterial pressure by 46 +/- 3 mmHg. An intravenous infusion of either meptazinol or naloxone (cumulative 2 mg kg-1, i.v.) partially restored blood pressure. In experimental animal models of haemorrhagic shock, meptazinol has a similar cardiovascular profile to naloxone. The established analgesic activity of meptazinol may confer an advantage in some shock states. PMID:4052729

  20. Index finger somatosensory evoked potentials in blind Braille readers.

    Giriyappa, Dayananda; Subrahmanyam, Roopakala Mysore; Rangashetty, Srinivasa; Sharma, Rajeev

    2009-01-01

    Traditionally, vision has been considered the dominant modality in our multi-sensory perception of the surrounding world. Sensory input via non-visual tracts becomes of greater behavioural relevance in totally blind individuals to enable effective interaction with the world around them. These include audition and tactile perceptions, leading to an augmentation in these perceptions when compared with normal sighted individuals. The objective of the present work was to study the index finger somatosensory evoked potentials (SEPs) in totally blind and normal sighted individuals. SEPs were recorded in 15 Braille reading totally blind females and compared with 15 age-matched normal sighted females. Latency and amplitudes of somatosensory evoked potential waveforms (N9, N13, and N20) were measured. Amplitude of N20 SEP (a cortical somatosensory evoked potential) was significantly larger in the totally blind than in normal sighted individuals (p Braille reading right index finger. Totally blind Braille readers have larger N20 amplitude, suggestive of greater somatosensory cortical representation of the Braille reading index finger.

  1. Neuronal Rac1 Is Required for Learning-Evoked Neurogenesis

    Anderson, Matthew P.; Freewoman, Julia; Cord, Branden; Babu, Harish; Brakebusch, Cord

    2013-01-01

    Hippocampus-dependent learning and memory relies on synaptic plasticity as well as network adaptations provided by the addition of adult-born neurons. We have previously shown that activity-induced intracellular signaling through the Rho family small GTPase Rac1 is necessary in forebrain projection neurons for normal synaptic plasticity in vivo, and here we show that selective loss of neuronal Rac1 also impairs the learning-evoked increase in neurogenesis in the adult mouse hippocampus. Earlier work has indicated that experience elevates the abundance of adult-born neurons in the hippocampus primarily by enhancing the survival of neurons produced just before the learning event. Loss of Rac1 in mature projection neurons did reduce learning-evoked neurogenesis but, contrary to our expectations, these effects were not mediated by altering the survival of young neurons in the hippocampus. Instead, loss of neuronal Rac1 activation selectively impaired a learning-evoked increase in the proliferation and accumulation of neural precursors generated during the learning event itself. This indicates that experience-induced alterations in neurogenesis can be mechanistically resolved into two effects: (1) the well documented but Rac1-independent signaling cascade that enhances the survival of young postmitotic neurons; and (2) a previously unrecognized Rac1-dependent signaling cascade that stimulates the proliferative production and retention of new neurons generated during learning itself. PMID:23884931

  2. Perceptual learning of acoustic noise generates memory-evoked potentials.

    Andrillon, Thomas; Kouider, Sid; Agus, Trevor; Pressnitzer, Daniel

    2015-11-02

    Experience continuously imprints on the brain at all stages of life. The traces it leaves behind can produce perceptual learning [1], which drives adaptive behavior to previously encountered stimuli. Recently, it has been shown that even random noise, a type of sound devoid of acoustic structure, can trigger fast and robust perceptual learning after repeated exposure [2]. Here, by combining psychophysics, electroencephalography (EEG), and modeling, we show that the perceptual learning of noise is associated with evoked potentials, without any salient physical discontinuity or obvious acoustic landmark in the sound. Rather, the potentials appeared whenever a memory trace was observed behaviorally. Such memory-evoked potentials were characterized by early latencies and auditory topographies, consistent with a sensory origin. Furthermore, they were generated even on conditions of diverted attention. The EEG waveforms could be modeled as standard evoked responses to auditory events (N1-P2) [3], triggered by idiosyncratic perceptual features acquired through learning. Thus, we argue that the learning of noise is accompanied by the rapid formation of sharp neural selectivity to arbitrary and complex acoustic patterns, within sensory regions. Such a mechanism bridges the gap between the short-term and longer-term plasticity observed in the learning of noise [2, 4-6]. It could also be key to the processing of natural sounds within auditory cortices [7], suggesting that the neural code for sound source identification will be shaped by experience as well as by acoustics. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Normalization reduces intersubject variability in cervical vestibular evoked myogenic potentials.

    van Tilburg, Mark J; Herrmann, Barbara S; Guinan, John J; Rauch, Steven D

    2014-09-01

    Cervical vestibular evoked myogenic potentials are used to assess saccular and inferior vestibular nerve function. Normalization of the VEMP waveform has been proposed to reduce the variability in vestibular evoked myogenic potentials by correcting for muscle activation. In this study, we test the hypothesis that normalization of the raw cervical VEMP waveform causes a significant decrease in the intersubject variability. Prospective cohort study. Large specialty hospital, department of otolaryngology. Twenty healthy subjects were used in this study. All subjects underwent cervical vestibular evoked myogenic potential testing using short tone bursts at 250, 500, 750, and 1,000 Hz. Both intersubject and intrasubject variability was assessed. Variability between raw and normalized peak-to-peak amplitudes was compared using the coefficient of variation. Intrasubject variability was assessed using the intraclass correlation coefficient and interaural asymmetry ratio. cVEMPs were present in most ears. Highest peak-to-peak amplitudes were recorded at 750 Hz. Normalization did not alter cVEMP tuning characteristics. Normalization of the cVEMP response caused a significant reduction in intersubject variability of the peak-to-peak amplitude. No significant change was seen in the intrasubject variability. Normalization significantly reduces cVEMP intersubject variability in healthy subjects without altering cVEMP characteristics. By reducing cVEMP amplitude variation due to nonsaccular, muscle-related factors, cVEMP normalization is expected to improve the ability to distinguish between healthy and pathologic responses in the clinical application of cVEMP testing.

  4. Nonlinearity, Conservation Law and Shocks

    Almost all natural phenomena, and social and economic changes, .... reference moving with velocity c also by the same symbol x and ... abstract as can be seen from the publication of the book Shock Waves and Reaction Diffusion Equation.

  5. Shock Thermodynamic Applied Research Facility

    Federal Laboratory Consortium — The Shock Thermodynamic Applied Research Facility (STAR) facility, within Sandia’s Solid Dynamic Physics Department, is one of a few institutions in the world with a...

  6. Target design for shock ignition

    Schurtz, G; Ribeyre, X; Lafon, M

    2010-01-01

    The conventional approach of laser driven inertial fusion involves the implosion of cryogenic shells of deuterium-tritium ice. At sufficiently high implosion velocities, the fuel ignites by itself from a central hot spot. In order to reduce the risks of hydrodynamic instabilities inherent to large implosion velocities, it was proposed to compress the fuel at low velocity, and ignite the compressed fuel by means of a convergent shock wave driven by an intense spike at the end of the laser pulse. This scheme, known as shock ignition, reduces the risks of shell break-up during the acceleration phase, but it may be impeded by a low coupling efficiency of the laser pulse with plasma at high intensities. This work provides a relationship between the implosion velocity and the laser intensity required to ignite the target by a shock. The operating domain of shock ignition at different energies is described.

  7. Undercuts by Laser Shock Forming

    Wielage, Hanna; Vollertsen, Frank

    2011-01-01

    In laser shock forming TEA-CO 2 -laser induced shock waves are used to form metal foils, such as aluminum or copper. The process utilizes an initiated plasma shock wave on the target surface, which leads to a forming of the foil. A challenge in forming technologies is the manufacturing of undercuts. By conventional forming methods these special forms are not feasible. In this article, it is presented that undercuts in the micro range can be produced by laser shock deep drawing. Different drawing die diameters, drawing die depths and the material aluminum in the thicknesses 20 and 50 μm were investigated. It will be presented that smaller die diameters facilitate undercuts compared to bigger die diameters. The phenomena can be explained by Barlow's formula. Furthermore, it is shown which maximum undercut depth at different die diameters can be reached. To this end, cross-sections of the different parameter combinations are displayed.

  8. Electric Shock Injuries in Children

    ... Issues Listen Español Text Size Email Print Share Electric Shock Injuries in Children Page Content ​When the ... comes into direct contact with a source of electricity, the current passes through it, producing what's called ...

  9. Relativistic shocks and particle acceleration

    Heavens, A.F.

    1988-01-01

    In this paper, we investigate the fluid dynamics of relativistic shock waves, and use the results to calculate the spectral index of particles accelerated by the Fermi process in such shocks. We have calculated the distributions of Fermi-accelerated particles at shocks propagating into cold proton-electron plasma and also cold electron-positron plasma. We have considered two different power spectra for the scattering waves, and find, in contrast to the non-relativistic case, that the spectral index of the accelerated particles depends on the wave power spectrum. On the assumption of thermal equilibrium both upstream and downstream, we present some useful fits for the compression ratio of shocks propagating at arbitrary speeds into gas of any temperature. (author)

  10. Shock wave interaction with turbulence: Pseudospectral simulations

    Buckingham, A.C.

    1986-01-01

    Shock waves amplify pre-existing turbulence. Shock tube and shock wave boundary layer interaction experiments provide qualitative confirmation. However, shock pressure, temperature, and rapid transit complicate direct measurement. Computational simulations supplement the experimental data base and help isolate the mechanisms responsible. Simulations and experiments, particularly under reflected shock wave conditions, significantly influence material mixing. In these pseudospectral Navier-Stokes simulations the shock wave is treated as either a moving (tracked or fitted) domain boundary. The simulations assist development of code mix models. Shock Mach number and pre-existing turbulence intensity initially emerge as key parameters. 20 refs., 8 figs

  11. Binaural interaction in auditory evoked potentials: Brainstem, middle- and long-latency components

    McPherson, DL; Starr, A

    1993-01-01

    Binaural interaction occurs in the auditory evoked potentials when the sum of the monaural auditory evoked potentials are not equivalent to the binaural evoked auditory potentials. Binaural interaction of the early- (0-10 ms), middle- (10-50 ms) and long-latency (50-200 ms) auditory evoked potentials was studied in 17 normal young adults. For the early components, binaural interaction was maximal at 7.35 ms accounting for a reduction of 21% of the amplitude of the binaural evoked potentials. ...

  12. The Efficacy of Cognitive Shock

    2015-05-21

    way, causing dissonance or cognitive conflict, so that the mental model has to be ‘accommodated’ to the new data. Categories and knowledge have to...The Efficacy of Cognitive Shock A Monograph by MAJ Anthony L. Marston United States Army School of Advanced Military Studies...DATES COVERED (From - To) JUN 2014 – MAY 2015 4. TITLE AND SUBTITLE The Efficacy of Cognitive Shock 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

  13. Pressurized Thermal Shock, Pts

    Boyd, C.

    2008-01-01

    Pressurized Thermal Shock (Pts) refers to a condition that challenges the integrity of the reactor pressure vessel. The root cause of this problem is the radiation embrittlement of the reactor vessel. This embrittlement leads to an increase in the reference temperature for nil ductility transition (RTNDT). RTNDT can increase to the point where the reactor vessel material can loose fracture toughness during overcooling events. The analysis of the risk of having a Pts for a specific plant is a multi-disciplinary problem involving probabilistic risk analysis (PRA), thermal-hydraulic analysis, and ultimately a structural and fracture analysis of the vessel wall. The PRA effort involves the postulation of overcooling events and ultimately leads to an integrated risk analysis. The thermal-hydraulic effort involves the difficult task of predicting the system behavior during a postulated overcooling scenario with a special emphasis on predicting the thermal and mechanic loadings on the reactor pressure vessel wall. The structural and fracture analysis of the reactor vessel wall relies on the thermal-hydraulic conditions as boundary conditions. The US experience has indicated that medium and large diameter primary system breaks dominate the risk of Pts along with scenarios that involve a stuck open valve (and associated system cooldown) that recloses resulting in system re-pressurization while the vessel wall is cool.

  14. Sepsis and septic shock

    Hotchkiss, Richard S.; Moldawer, Lyle L.; Opal, Steven M.; Reinhart, Konrad; Turnbull, Isaiah R.; Vincent, Jean-Louis

    2017-01-01

    For more than two decades, sepsis was defined as a microbial infection that produces fever (or hypothermia), tachycardia, tachypnoea and blood leukocyte changes. Sepsis is now increasingly being considered a dysregulated systemic inflammatory and immune response to microbial invasion that produces organ injury for which mortality rates are declining to 15–25%. Septic shock remains defined as sepsis with hyperlactataemia and concurrent hypotension requiring vasopressor therapy, with in-hospital mortality rates approaching 30–50%. With earlier recognition and more compliance to best practices, sepsis has become less of an immediate life-threatening disorder and more of a long-term chronic critical illness, often associated with prolonged inflammation, immune suppression, organ injury and lean tissue wasting. Furthermore, patients who survive sepsis have continuing risk of mortality after discharge, as well as long-term cognitive and functional deficits. Earlier recognition and improved implementation of best practices have reduced in-hospital mortality, but results from the use of immunomodulatory agents to date have been disappointing. Similarly, no biomarker can definitely diagnose sepsis or predict its clinical outcome. Because of its complexity, improvements in sepsis outcomes are likely to continue to be slow and incremental. PMID:28117397

  15. Focusing of Shear Shock Waves

    Giammarinaro, Bruno; Espíndola, David; Coulouvrat, François; Pinton, Gianmarco

    2018-01-01

    Focusing is a ubiquitous way to transform waves. Recently, a new type of shock wave has been observed experimentally with high-frame-rate ultrasound: shear shock waves in soft solids. These strongly nonlinear waves are characterized by a high Mach number, because the shear wave velocity is much slower, by 3 orders of magnitude, than the longitudinal wave velocity. Furthermore, these waves have a unique cubic nonlinearity which generates only odd harmonics. Unlike longitudinal waves for which only compressional shocks are possible, shear waves exhibit cubic nonlinearities which can generate positive and negative shocks. Here we present the experimental observation of shear shock wave focusing, generated by the vertical motion of a solid cylinder section embedded in a soft gelatin-graphite phantom to induce linearly vertically polarized motion. Raw ultrasound data from high-frame-rate (7692 images per second) acquisitions in combination with algorithms that are tuned to detect small displacements (approximately 1 μ m ) are used to generate quantitative movies of gel motion. The features of shear shock wave focusing are analyzed by comparing experimental observations with numerical simulations of a retarded-time elastodynamic equation with cubic nonlinearities and empirical attenuation laws for soft solids.

  16. Shock compression of synthetic opal

    Inoue, A; Okuno, M; Okudera, H; Mashimo, T; Omurzak, E; Katayama, S; Koyano, M

    2010-01-01

    Structural change of synthetic opal by shock-wave compression up to 38.1 GPa has been investigated by using SEM, X-ray diffraction method (XRD), Infrared (IR) and Raman spectroscopies. Obtained information may indicate that the dehydration and polymerization of surface silanole due to high shock and residual temperature are very important factors in the structural evolution of synthetic opal by shock compression. Synthetic opal loses opalescence by 10.9 and 18.4 GPa of shock pressures. At 18.4 GPa, dehydration and polymerization of surface silanole and transformation of network structure may occur simultaneously. The 4-membered ring of TO 4 tetrahedrons in as synthetic opal may be relaxed to larger ring such as 6-membered ring by high residual temperature. Therefore, the residual temperature may be significantly high at even 18.4 GPa of shock compression. At 23.9 GPa, opal sample recovered the opalescence. Origin of this opalescence may be its layer structure by shock compression. Finally, sample fuse by very high residual temperature at 38.1 GPa and the structure closes to that of fused SiO 2 glass. However, internal silanole groups still remain even at 38.1 GPa.

  17. Computations of slowly moving shocks

    Karni, S.; Canic, S.

    1997-01-01

    Computations of slowly moving shocks by shock capturing schemes may generate oscillations are generated already by first-order schemes, but become more pronounced in higher-order schemes which seem to exhibit different behaviors: (i) the first-order upwind (UW) scheme which generates strong oscillations and (ii) the Lax-Friedrichs scheme which appears not to generate any disturbances at all. A key observation is that in the UW case, the numerical viscosity in the shock family vanishes inside the slow shock layer. Simple scaling arguments show the third-order effects on the solution may no longer be neglected. We derive the third-order modified equation for the UW scheme and regard the oscillatory solution as a traveling wave solution of the parabolic modified equation for the perturbation. We then look at the governing equation for the perturbation, which points to a plausible mechanism by which postshock oscillations are generated. It contains a third-order source term that becomes significant inside the shock layer, and a nonlinear coupling term which projects the perturbation on all characteristic fields, including those not associated with the shock family. 5 refs., 8 figs

  18. Shock compression of synthetic opal

    Inoue, A.; Okuno, M.; Okudera, H.; Mashimo, T.; Omurzak, E.; Katayama, S.; Koyano, M.

    2010-03-01

    Structural change of synthetic opal by shock-wave compression up to 38.1 GPa has been investigated by using SEM, X-ray diffraction method (XRD), Infrared (IR) and Raman spectroscopies. Obtained information may indicate that the dehydration and polymerization of surface silanole due to high shock and residual temperature are very important factors in the structural evolution of synthetic opal by shock compression. Synthetic opal loses opalescence by 10.9 and 18.4 GPa of shock pressures. At 18.4 GPa, dehydration and polymerization of surface silanole and transformation of network structure may occur simultaneously. The 4-membered ring of TO4 tetrahedrons in as synthetic opal may be relaxed to larger ring such as 6-membered ring by high residual temperature. Therefore, the residual temperature may be significantly high at even 18.4 GPa of shock compression. At 23.9 GPa, opal sample recovered the opalescence. Origin of this opalescence may be its layer structure by shock compression. Finally, sample fuse by very high residual temperature at 38.1 GPa and the structure closes to that of fused SiO2 glass. However, internal silanole groups still remain even at 38.1 GPa.

  19. Shock compression of synthetic opal

    Inoue, A; Okuno, M; Okudera, H [Department of Earth Sciences, Kanazawa University Kanazawa, Ishikawa, 920-1192 (Japan); Mashimo, T; Omurzak, E [Shock Wave and Condensed Matter Research Center, Kumamoto University, Kumamoto, 860-8555 (Japan); Katayama, S; Koyano, M, E-mail: okuno@kenroku.kanazawa-u.ac.j [JAIST, Nomi, Ishikawa, 923-1297 (Japan)

    2010-03-01

    Structural change of synthetic opal by shock-wave compression up to 38.1 GPa has been investigated by using SEM, X-ray diffraction method (XRD), Infrared (IR) and Raman spectroscopies. Obtained information may indicate that the dehydration and polymerization of surface silanole due to high shock and residual temperature are very important factors in the structural evolution of synthetic opal by shock compression. Synthetic opal loses opalescence by 10.9 and 18.4 GPa of shock pressures. At 18.4 GPa, dehydration and polymerization of surface silanole and transformation of network structure may occur simultaneously. The 4-membered ring of TO{sub 4} tetrahedrons in as synthetic opal may be relaxed to larger ring such as 6-membered ring by high residual temperature. Therefore, the residual temperature may be significantly high at even 18.4 GPa of shock compression. At 23.9 GPa, opal sample recovered the opalescence. Origin of this opalescence may be its layer structure by shock compression. Finally, sample fuse by very high residual temperature at 38.1 GPa and the structure closes to that of fused SiO{sub 2} glass. However, internal silanole groups still remain even at 38.1 GPa.

  20. Electromagnetically driven radiative shocks and their measurements

    Kondo, K.; Watanabe, M.; Nakajima, M.; Kawamura, T.; Horioka, K.

    2005-01-01

    Experimental results on a generation of strong shocks in a compact pulse power device are reported. The characteristics of strong shocks are different from hydrodynamical shocks' because they depend on not only collisions but radiation processes. Radiative shocks are relevant to high energy density phenomena such as the explosions of supernovae. When initial pressure is lower than about 50 mtorr, an interesting structure is confirmed at the shock front, which might indicate a phenomenon proceeded by the radiative process. (author)

  1. Pressurized thermal shock (PTS)

    Rosso, Ricardo D.; Ventura, Mirta A.

    2006-01-01

    In the present work, a description of Thermal Shock in Pressurized conditions (PTS), and its influence in the treatment of the integrity of the pressure vessel (RPV) of a Pressurized Water Reactor (PWR) and/or of a Heavy water Pressurized water Reactor (PHWR) is made. Generally, the analysis of PTS involves a process of three stages: a-) Modeling with a System Code of relevant thermohydraulics transients in reference with the thermal shock; b-) The local distribution of temperatures in the downcomer and the heat transference coefficients from the RPV wall to the fluid, are determined; c-) The fracture mechanical analysis. These three stages are included in this work: Results with the thermohydraulics code Relap5/mod.3, are obtained, for a LOCA scenario in the hot leg of the cooling System of the Primary System of the CAN-I reactor. The method used in obtaining results is described. A study on the basis of lumped parameters of the local evolutions of the temperature of the flow is made, in the downcomer of the reactor pressure vessel. The purpose of this study is to determine how the intensification of the stress coefficient, varies in function of the emergency injected water during the thermohydraulic transients that take place under the imposed conditions in the postulated scene. Specially, it is considered a 50 cm 2 break, located in the neighborhoods of the pressurized with the corresponding hot leg connection. This size is considered like the most critical. The method used to obtain the results is described. The fracture mechanical analysis is made. From the obtained results we confirmed that we have a simple tool of easy application in order to analyze phenomena of the type PTS in the postulated scenes by break in the cold and hot legs of the primary system. This methodology of calculus is completely independent of the used ones by the Nucleoelectrica Argentina S.A. (NASA) in the analysis of the PTS phenomena in the CAN-I. The results obtained with the adopted

  2. Radiation- and pair-loaded shocks

    Lyutikov, Maxim

    2018-06-01

    We consider the structure of mildly relativistic shocks in dense media, taking into account the radiation and pair loading, and diffusive radiation energy transfer within the flow. For increasing shock velocity (increasing post-shock temperature), the first important effect is the efficient energy redistribution by radiation within the shock that leads to the appearance of an isothermal jump, whereby the flow reaches the final state through a discontinuous isothermal transition. The isothermal jump, on scales much smaller than the photon diffusion length, consists of a weak shock and a quick relaxation to the isothermal conditions. Highly radiation-dominated shocks do not form isothermal jump. Pair production can mildly increase the overall shock compression ratio to ≈10 (4 for matter-dominated shocks and 7 of the radiation-dominated shocks).

  3. Prediction of massive bleeding. Shock index and modified shock index.

    Terceros-Almanza, L J; García-Fuentes, C; Bermejo-Aznárez, S; Prieto-Del Portillo, I J; Mudarra-Reche, C; Sáez-de la Fuente, I; Chico-Fernández, M

    2017-12-01

    To determine the predictive value of the Shock Index and Modified Shock Index in patients with massive bleeding due to severe trauma. Retrospective cohort. Severe trauma patient's initial attention at the intensive care unit of a tertiary hospital. Patients older than 14 years that were admitted to the hospital with severe trauma (Injury Severity Score >15) form January 2014 to December 2015. We studied the sensitivity (Se), specificity (Sp), positive and negative predictive value (PV+ and PV-), positive and negative likelihood ratio (LR+ and LR-), ROC curves (Receiver Operating Characteristics) and the area under the same (AUROC) for prediction of massive hemorrhage. 287 patients were included, 76.31% (219) were male, mean age was 43,36 (±17.71) years and ISS was 26 (interquartile range [IQR]: 21-34). The overall frequency of massive bleeding was 8.71% (25). For Shock Index: AUROC was 0.89 (95% confidence intervals [CI] 0.84 to 0.94), with an optimal cutoff at 1.11, Se was 91.3% (95% CI: 73.2 to 97.58) and Sp was 79.69% (95% CI: 74.34 to 84.16). For the Modified Shock Index: AUROC was 0.90 (95% CI: 0.86 to 0.95), with an optimal cutoff at 1.46, Se was 95.65% (95% CI: 79.01 to 99.23) and Sp was 75.78% (95% CI: 70.18 to 80.62). Shock Index and Modified Shock Index are good predictors of massive bleeding and could be easily incorporated to the initial workup of patients with severe trauma. Copyright © 2017 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

  4. Shock diffraction in alumina powder

    Venz, G.; Killen, P.D.; Page, N.W.

    1996-01-01

    In order to produce complex shaped components by dynamic compaction of ceramic powders detailed knowledge of their response under shock loading conditions is required. This work attempts to provide data on release effects and shock attenuation in 1 μm and 5 μm α-alumina powders which were compacted to between 85 % and 95 % of the solid phase density by the impact of high velocity steel projectiles. As in previous work, the powder was loaded into large cylindrical dies with horizontal marker layers of a contrasting coloured powder to provide a record of powder displacement in the recovered specimens. After recovery and infiltration with a thermosetting resin the specimens were sectioned and polished to reveal the structure formed by the passage of the projectile and shock wave. Results indicate that the shock pressures generated were of the order of 0.5 to 1.4 GPa and higher, with shock velocities and sound speeds in the ranges 650 to 800 m/s and 350 to 400 m/s respectively

  5. Transient shocks beyond the heliopause

    Fermo, R L; Pogorelov, N V; Burlaga, L F

    2015-01-01

    The heliopause is a rich, dynamic surface affected by the time-dependent solar wind. Stream interactions due to coronal mass ejections (CMEs), corotating interaction regions (CIRs), and other transient phenomena are known to merge producing global merged interaction regions (GMIRs). Numerical simulations of the solar wind interaction with the local interstellar medium (LISM) show that GMIRs, as well other time-dependent structures in the solar wind, may produce compression/rarefaction waves and shocks in the LISM behind the heliopause. These shocks may initiate wave activity observed by the Voyager spacecraft. The magnetometer onboard Voyager 1 indeed observed a few structures that may be interpreted as shocks. We present numerical simulations of such shocks in the year of 2000, when both Voyager spacecraft were in the supersonic solar wind region, and in 2012, when Voyager 1 observed traveling shocks. In the former case, Voyager observations themselves provide time- dependent boundary conditions in the solar wind. In the latter case, we use OMNI data at 1 AU to analyze the plasma and magnetic field behavior after Voyager 1 crossed the heliospheric boundary. Numerical results are compared with spacecraft observations. (paper)

  6. Cortical modulation of short-latency TMS-evoked potentials

    Domenica eVeniero

    2013-01-01

    Full Text Available Transcranial magnetic stimulation - electroencephalogram (TMS-EEG co-registration offers the opportunity to test reactivity of brain areas across distinct conditions through TMS-evoked potentials (TEPs. Several TEPs have been described, their functional meaning being largely unknown. In particular, short-latency potentials peaking at 5 (P5 and 8 (N8 ms after the TMS pulse have been recently described, but because of their huge amplitude, the problem of whether their origin is cortical or not has been opened. To gain information about these components, we employed a protocol that modulates primary motor cortex excitability (MI through an exclusively cortical phenomena: low frequency stimulation of premotor area (PMC. TMS was applied simultaneously with EEG recording from 70 electrodes. Amplitude of TEPs evoked by 200 single-pulses TMS delivered over MI at 110% of resting motor threshold was measured before and after applying 900 TMS conditioning stimuli to left premotor cortex with 1 Hz repetition rate. Single subject analyses showed reduction in TEPs amplitude after PMC conditioning in a sample of participants and increase in TEPs amplitude in two subjects. No effects were found on corticospinal excitability as recorded by motor evoked potentials (MEPs. Furthermore, correlation analysis showed an inverse relation between the effects of the conditioning protocol on P5-N8 complex amplitude and MEPs amplitude. Because the effects of the used protocol have been ascribed to a cortical interaction between premotor area and MI, we suggest that despite the sign of P5-N8 amplitude modulation is not consistent across participant, this modulation could indicate, at least in part, their cortical origin. We conclude that with an accurate experimental procedure early-latency components can be used to evaluate the reactivity of the stimulated cortex.

  7. Temporal suppression and augmentation of click-evoked otoacoustic emissions

    Verhulst, Sarah; Harte, James; Dau, Torsten

    2008-01-01

    This study investigates and models temporal suppression of click-evoked otoacoustic emissions (CEOAEs). This suppression-effect is created when a suppressor-click is presented close in time to a test-click. The analysis was carried out for short time-frames of short- and long-latency CEOAEs...... suppression is present in all CEOAEs for inter-click intervals (ICIs) less than 8 ms. The long-latency CEOAEs showed augmentation (i.e., negative suppression) for ICIs of 6-7 ms which was not reported for the short-latency CEOAE at these ICIs. A phenomenological approach is adopted here to explain both...

  8. Temporary hyperthyroidism (hypertriiodothyroninemia) to be evoked by stress

    Ehni, A.; Kampmann, H.

    1982-01-01

    From patients of intensive care unit suffering from acute myocardial infarction, decompensated hypertension with left heart insufficiency, severe coronary heart disease, pulmonary infarction, cerebral ischemia 102 were selected with suspicion of hyperthyroidism because of clinical signs. 12 patients fulfilled the criteria of temporary hyperthyroidism, 6 patients revealed persistent hyperthyroidism. Excluding other causes for evoked hyperthyroidism as common etiological factor psychogenic stress is discussed. It is concluded, that increased thyroid hormone concentration in patients of intensive care units should be controlled within a short time in order to delineate temporary hyperthyroidism against permanent hyperthyroidism. (orig.) [de

  9. Temporary hyperthyroidism (hypertriiodothyroninemia) to be evoked by stress

    Ehni, A.; Kampmann, H.

    1982-10-01

    From patients of intensive care unit suffering from acute myocardial infarction, decompensated hypertension with left heart insufficiency, severe coronary heart disease, pulmonary infarction, cerebral ischemia 102 were selected with suspicion of hyperthyroidism because of clinical signs. 12 patients fulfilled the criteria of temporary hyperthyroidism, 6 patients revealed persistent hyperthyroidism. Excluding other causes for evoked hyperthyroidism as common etiological factor psychogenic stress is discussed. It is concluded, that increased thyroid hormone concentration in patients of intensive care units should be controlled within a short time in order to delineate temporary hyperthyroidism against permanent hyperthyroidism.

  10. Energetic ion acceleration at collisionless shocks

    Decker, R. B.; Vlahos, L.

    1985-01-01

    An example is presented from a test particle simulation designed to study ion acceleration at oblique turbulent shocks. For conditions appropriate at interplanetary shocks near 1 AU, it is found that a shock with theta sub B n = 60 deg is capable of producing an energy spectrum extending from 10 keV to approx. 1 MeV in approx 1 hour. In this case total energy gains result primarily from several separate episodes of shock drift acceleration, each of which occurs when particles are scattered back to the shock by magnetic fluctuations in the shock vicinity.

  11. Energetic ion acceleration at collisionless shocks

    Decker, R.B.; Vlahos, L.

    1985-01-01

    An example is presented from a test particle simulation designed to study ion acceleration at oblique turbulent shocks. For conditions appropriate at interplanetary shocks near 1 AU, it is found that a shock with theta sub B n = 60 deg is capable of producing an energy spectrum extending from 10 keV to approx 1 MeV in approx 1 hour. In this case total energy gains result primarily from several separate episodes of shock drift acceleration, each of which occurs when particles are scattered back to the shock by magnetic fluctuations in the shock vicinity

  12. Why the Nature of Oil Shocks Matters

    Archanskaia, Elizaveta; Hubert, Paul; Creel, Jerome

    2009-03-01

    This article studies the impact of oil shocks on the macro-economy in two ways insofar unexploited in the literature. The analysis is conducted at the global level, and it explicitly accounts for the potentially changing nature of oil shocks. Based on an original world GDP series and a grouping of oil shocks according to their nature, we find that oil supply shocks negatively impact world growth, contrary to oil demand shocks, pro-cyclical in their nature. This result is robust at the national level for the US. Furthermore, endogenous monetary policy is shown to have no counter-cyclical effects in the context of an oil demand shock. (authors)

  13. MHD intermediate shock discontinuities: Pt. 1

    Kennel, C.F.; Blandford, R.D.; Coppi, P.

    1989-01-01

    Recent numerical investigations have focused attention once more on the role of intermediate shocks in MHD. Four types of intermediate shock are identified using a graphical representation of the MHD Rankine-Hugoniot conditions. This same representation can be used to exhibit the close relationship of intermediate shocks to switch-on shocks and rotational discontinuities. The conditions under which intermediate discontinuities can be found are elucidated. The variations in velocity, pressure, entropy and magnetic-field jumps with upstream parameters in intermediate shocks are exhibited graphically. The evolutionary arguments traditionally advanced against intermediate shocks may fail because the equations of classical MHD are not strictly hyperbolic. (author)

  14. Shock waves in weakly compressed granular media.

    van den Wildenberg, Siet; van Loo, Rogier; van Hecke, Martin

    2013-11-22

    We experimentally probe nonlinear wave propagation in weakly compressed granular media and observe a crossover from quasilinear sound waves at low impact to shock waves at high impact. We show that this crossover impact grows with the confining pressure P0, whereas the shock wave speed is independent of P0-two hallmarks of granular shocks predicted recently. The shocks exhibit surprising power law attenuation, which we model with a logarithmic law implying that shock dissipation is weak and qualitatively different from other granular dissipation mechanisms. We show that elastic and potential energy balance in the leading part of the shocks.

  15. Shock, diaschisis and von Monakow

    Eliasz Engelhardt

    2013-07-01

    Full Text Available The concept of shock apparently emerged in the middle of the 18th century (Whyett as an occurrence observed experimentally after spinal cord transection, and identified as "shock" phenomenon one century later (Hall. The concept was extended (Brown-Séquard and it was suggested that brain lesions caused functional rupture in regions distant from the injured one ("action à distance". The term "diaschisis" (von Monakow, proposed as a new modality of shock, had its concept broadened, underpinned by observations of patients, aiming at distinguishing between symptoms of focal brain lesions and transitory effects they produced, attributable to depression of distant parts of the brain connected to the injured area. Presently, diaschisis is related mainly to cerebrovascular lesions and classified according to the connection fibers involved, as proposed by von Monakow. Depression of metabolism and blood flow in regions anatomically separated, but related by connections with the lesion, allows observing diaschisis with neuroimaging.

  16. Shock compression of geological materials

    Kirk, S; Braithwaite, C; Williamson, D; Jardine, A

    2014-01-01

    Understanding the shock compression of geological materials is important for many applications, and is particularly important to the mining industry. During blast mining the response to shock loading determines the wave propagation speed and resulting fragmentation of the rock. The present work has studied the Hugoniot of two geological materials; Lake Quarry Granite and Gosford Sandstone. For samples of these materials, the composition was characterised in detail. The Hugoniot of Lake Quarry Granite was predicted from this information as the material is fully dense and was found to be in good agreement with the measured Hugoniot. Gosford Sandstone is porous and undergoes compaction during shock loading. Such behaviour is similar to other granular material and we show how it can be described using a P-a compaction model.

  17. Shock compression of simulated adobe

    Braithwaite, C. H.; Church, P. D.; Gould, P. J.; Stewart, B.; Jardine, A. P.

    2017-01-01

    A series of plate impact experiments were conducted to investigate the shock response of a simulant for adobe, a traditional form of building material widely used around the world. Air dried bricks were sourced from the London brick company, dry machined and impacted at a range of velocities in a single stage gas gun. The shock Hugoniot was determined (Us =2.26up+0.37) as well as release information. The material was found to behave in a manner which was similar to that of loose sand and considerably less stiff than a weak porous sandstone. The effect of any cementing of the grains was examined by shocking powdered samples contained within a cell arrangement.

  18. Shock Initiation of Damaged Explosives

    Chidester, S K; Vandersall, K S; Tarver, C M

    2009-10-22

    Explosive and propellant charges are subjected to various mechanical and thermal insults that can increase their sensitivity over the course of their lifetimes. To quantify this effect, shock initiation experiments were performed on mechanically and thermally damaged LX-04 (85% HMX, 15% Viton by weight) and PBX 9502 (95% TATB, 5% Kel-F by weight) to obtain in-situ manganin pressure gauge data and run distances to detonation at various shock pressures. We report the behavior of the HMX-based explosive LX-04 that was damaged mechanically by applying a compressive load of 600 psi for 20,000 cycles, thus creating many small narrow cracks, or by cutting wedge shaped parts that were then loosely reassembled, thus creating a few large cracks. The thermally damaged LX-04 charges were heated to 190 C for long enough for the beta to delta solid - solid phase transition to occur, and then cooled to ambient temperature. Mechanically damaged LX-04 exhibited only slightly increased shock sensitivity, while thermally damaged LX-04 was much more shock sensitive. Similarly, the insensitive explosive PBX 9502 was mechanically damaged using the same two techniques. Since PBX 9502 does not undergo a solid - solid phase transition but does undergo irreversible or 'rachet' growth when thermally cycled, thermal damage to PBX 9502 was induced by this procedure. As for LX-04, the thermally damaged PBX 9502 demonstrated a greater shock sensitivity than mechanically damaged PBX 9502. The Ignition and Growth reactive flow model calculated the increased sensitivities by igniting more damaged LX-04 and PBX 9502 near the shock front based on the measured densities (porosities) of the damaged charges.

  19. Shock compaction of molybdenum powder

    Ahrens, T. J.; Kostka, D.; Vreeland, T., Jr.; Schwarz, R. B.; Kasiraj, P.

    1983-01-01

    Shock recovery experiments which were carried out in the 9 to 12 GPa range on 1.4 distension Mo and appear adequate to compact to full density ( 45 (SIGMA)m) powders were examined. The stress levels, however, are below those calculated to be from 100 to approx. 22 GPa which a frictional heating model predicts are required to consolidate approx. 10 to 50 (SIGMA)m particles. The model predicts that powders that have a distension of m=1.6 shock pressures of 14 to 72 GPa are required to consolidate Mo powders in the 50 to 10 (SIGMA)m range.

  20. Cation disorder in shocked orthopyroxene.

    Dundon, R. W.; Hafner, S. S.

    1971-01-01

    The study of cation distributions over nonequivalent lattice sites in minerals may reveal information on the history of temperature and pressure in rocks. Chemically homogeneous orthopyroxene specimens were shocked under well-controlled conditions in the laboratory in order to provide a basis for the interpretation of more complex natural materials. As a result of the investigation it is concluded that the distribution of magnesium and iron over the M1 and M2 positions in Bamle enstatite shocked at 1 megabar is highly disordered. It corresponds to an equilibrium distribution of at least 1000 C.

  1. Sepsis and Septic Shock Strategies.

    Armstrong, Bracken A; Betzold, Richard D; May, Addison K

    2017-12-01

    Three therapeutic principles most substantially improve organ dysfunction and survival in sepsis: early, appropriate antimicrobial therapy; restoration of adequate cellular perfusion; timely source control. The new definitions of sepsis and septic shock reflect the inadequate sensitivity, specify, and lack of prognostication of systemic inflammatory response syndrome criteria. Sequential (sepsis-related) organ failure assessment more effectively prognosticates in sepsis and critical illness. Inadequate cellular perfusion accelerates injury and reestablishing perfusion limits injury. Multiple organ systems are affected by sepsis and septic shock and an evidence-based multipronged approach to systems-based therapy in critical illness results in improve outcomes. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Shock/shock interactions between bodies and wings

    Gaoxiang XIANG

    2018-02-01

    Full Text Available This paper examines the Shock/Shock Interactions (SSI between the body and wing of aircraft in supersonic flows. The body is simplified to a flat wedge and the wing is assumed to be a sharp wing. The theoretical spatial dimension reduction method, which transforms the 3D problem into a 2D one, is used to analyze the SSI between the body and wing. The temperature and pressure behind the Mach stem induced by the wing and body are obtained, and the wave configurations in the corner are determined. Numerical validations are conducted by solving the inviscid Euler equations in 3D with a Non-oscillatory and Non-free-parameters Dissipative (NND finite difference scheme. Good agreements between the theoretical and numerical results are obtained. Additionally, the effects of the wedge angle and sweep angle on wave configurations and flow field are considered numerically and theoretically. The influences of wedge angle are significant, whereas the effects of sweep angle on wave configurations are negligible. This paper provides useful information for the design and thermal protection of aircraft in supersonic and hypersonic flows. Keywords: Body and wing, Flow field, Hypersonic flow, Shock/shock interaction, Wave configurations

  3. Nostalgia-Evoked Inspiration: Mediating Mechanisms and Motivational Implications.

    Stephan, Elena; Sedikides, Constantine; Wildschut, Tim; Cheung, Wing-Yee; Routledge, Clay; Arndt, Jamie

    2015-10-01

    Six studies examined the nostalgia-inspiration link and its motivational implications. In Study 1, nostalgia proneness was positively associated with inspiration frequency and intensity. In Studies 2 and 3, the recollection of nostalgic (vs. ordinary) experiences increased both general inspiration and specific inspiration to engage in exploratory activities. In Study 4, serial mediational analyses supported a model in which nostalgia increases social connectedness, which subsequently fosters self-esteem, which then boosts inspiration. In Study 5, a rigorous evaluation of this serial mediational model (with a novel nostalgia induction controlling for positive affect) reinforced the idea that nostalgia-elicited social connectedness increases self-esteem, which then heightens inspiration. Study 6 extended the serial mediational model by demonstrating that nostalgia-evoked inspiration predicts goal pursuit (intentions to pursue an important goal). Nostalgia spawns inspiration via social connectedness and attendant self-esteem. In turn, nostalgia-evoked inspiration bolsters motivation. © 2015 by the Society for Personality and Social Psychology, Inc.

  4. Synaptically evoked glutamate transporter currents in Spinal Dorsal Horn Astrocytes

    Dougherty Patrick M

    2009-07-01

    Full Text Available Abstract Background Removing and sequestering synaptically released glutamate from the extracellular space is carried out by specific plasma membrane transporters that are primarily located in astrocytes. Glial glutamate transporter function can be monitored by recording the currents that are produced by co-transportation of Na+ ions with the uptake of glutamate. The goal of this study was to characterize glutamate transporter function in astrocytes of the spinal cord dorsal horn in real time by recording synaptically evoked glutamate transporter currents. Results Whole-cell patch clamp recordings were obtained from astrocytes in the spinal substantia gelatinosa (SG area in spinal slices of young adult rats. Glutamate transporter currents were evoked in these cells by electrical stimulation at the spinal dorsal root entry zone in the presence of bicuculline, strychnine, DNQX and D-AP5. Transporter currents were abolished when synaptic transmission was blocked by TTX or Cd2+. Pharmacological studies identified two subtypes of glutamate transporters in spinal astrocytes, GLAST and GLT-1. Glutamate transporter currents were graded with stimulus intensity, reaching peak responses at 4 to 5 times activation threshold, but were reduced following low-frequency (0.1 – 1 Hz repetitive stimulation. Conclusion These results suggest that glutamate transporters of spinal astrocytes could be activated by synaptic activation, and recording glutamate transporter currents may provide a means of examining the real time physiological responses of glial cells in spinal sensory processing, sensitization, hyperalgesia and chronic pain.

  5. Analytical solutions of hypersonic type IV shock - shock interactions

    Frame, Michael John

    An analytical model has been developed to predict the effects of a type IV shock interaction at high Mach numbers. This interaction occurs when an impinging oblique shock wave intersects the most normal portion of a detached bow shock. The flowfield which develops is complicated and contains an embedded jet of supersonic flow, which may be unsteady. The jet impinges on the blunt body surface causing very high pressure and heating loads. Understanding this type of interaction is vital to the designers of cowl lips and leading edges on air- breathing hypersonic vehicles. This analytical model represents the first known attempt at predicting the geometry of the interaction explicitly, without knowing beforehand the jet dimensions, including the length of the transmitted shock where the jet originates. The model uses a hyperbolic equation for the bow shock and by matching mass continuity, flow directions and pressure throughout the flowfield, a prediction of the interaction geometry can be derived. The model has been shown to agree well with the flowfield patterns and properties of experiments and CFD, but the prediction for where the peak pressure is located, and its value, can be significantly in error due to a lack of sophistication in the model of the jet fluid stagnation region. Therefore it is recommended that this region of the flowfield be modeled in more detail and more accurate experimental and CFD measurements be used for validation. However, the analytical model has been shown to be a fast and economic prediction tool, suitable for preliminary design, or for understanding the interactions effects, including the basic physics of the interaction, such as the jet unsteadiness. The model has been used to examine a wide parametric space of possible interactions, including different Mach number, impinging shock strength and location, and cylinder radius. It has also been used to examine the interaction on power-law shaped blunt bodies, a possible candidate for

  6. Skin denervation does not alter cortical potentials to surface concentric electrode stimulation: A comparison with laser evoked potentials and contact heat evoked potentials.

    La Cesa, S; Di Stefano, G; Leone, C; Pepe, A; Galosi, E; Alu, F; Fasolino, A; Cruccu, G; Valeriani, M; Truini, A

    2018-01-01

    In the neurophysiological assessment of patients with neuropathic pain, laser evoked potentials (LEPs), contact heat evoked potentials (CHEPs) and the evoked potentials by the intraepidermal electrical stimulation via concentric needle electrode are widely agreed as nociceptive specific responses; conversely, the nociceptive specificity of evoked potentials by surface concentric electrode (SE-PREPs) is still debated. In this neurophysiological study we aimed at verifying the nociceptive specificity of SE-PREPs. We recorded LEPs, CHEPs and SE-PREPs in eleven healthy participants, before and after epidermal denervation produced by prolonged capsaicin application. We also used skin biopsy to verify the capsaicin-induced nociceptive nerve fibre loss in the epidermis. We found that whereas LEPs and CHEPs were suppressed after capsaicin-induced epidermal denervation, the surface concentric electrode stimulation of the same denervated skin area yielded unchanged SE-PREPs. The suppression of LEPs and CHEPs after nociceptive nerve fibre loss in the epidermis indicates that these techniques are selectively mediated by nociceptive system. Conversely, the lack of SE-PREP changes suggests that SE-PREPs do not provide selective information on nociceptive system function. Capsaicin-induced epidermal denervation abolishes laser evoked potentials (LEPs) and contact heat evoked potentials (CHEPs), but leaves unaffected pain-related evoked potentials by surface concentric electrode (SE-PREPs). These findings suggest that unlike LEPs and CHEPs, SE-PREPs are not selectively mediated by nociceptive system. © 2017 European Pain Federation - EFIC®.

  7. "Driverless" Shocks in the Interplanetary Medium

    Gopalswamy, N.; Kaiser, M. L.; Lara, A.

    1999-01-01

    Many interplanetary shocks have been detected without an obvious driver behind them. These shocks have been thought to be either blast waves from solar flares or shocks due to sudden increase in solar wind speed caused by interactions between large scale open and closed field lines of the Sun. We investigated this problem using a set of interplanetary shock detected {\\it in situ} by the Wind space craft and tracing their solar origins using low frequency radio data obtained by the Wind/WAVES experiment. For each of these "driverless shocks" we could find a unique coronal mass ejections (CME) event observed by the SOHO (Solar and Heliospheric Observatory) coronagraphs. We also found that these CMEs were ejected at large angles from the Sun-Earth line. It appears that the "driverless shocks" are actually driver shocks, but the drivers were not intercepted by the spacecraft. We conclude that the interplanetary shocks are much more extended than the driving CMEs.

  8. Shock and Vibration. Volume 1, Issue 1

    Pilkey, Walter D

    1994-01-01

    ..., and earthquake engineering. Among the specific areas to be covered are vibration testing and control, vibration condition monitoring and diagnostics, shock hardenings, modal technology, shock testing, data acquisition, fluid...

  9. Initial ISEE magnetometer results: shock observation

    Russell, C.T.

    1979-01-01

    ISEE-1 and -2 magnetic field profiles across 6 terrestrial bow shock and one interplanetary shock are examined. The inteplanetary shock illustrates the behavior of a low Mach number shock. Three examples of low or moderate β, high Mach number, quasi-perpendicular shocks are examined. These did not have upstream waves, but rather had waves growing in the field gradient. Two examples of high β shocks showed little coherence in field variation even though the two vehicles were only a few hundred kilometers apart. The authors present the joint behavior of wave, particle and field data across some of these shocks to show some of the myriad of shock features whose behavior they are now beginning to investigate. (Auth.)

  10. 29th International Symposium on Shock Waves

    Ranjan, Devesh

    2015-01-01

    This proceedings present the results of the 29th International Symposium on Shock Waves (ISSW29) which was held in Madison, Wisconsin, U.S.A., from July 14 to July 19, 2013. It was organized by the Wisconsin Shock Tube Laboratory, which is part of the College of Engineering of the University of Wisconsin-Madison. The ISSW29 focused on the following areas: Blast Waves, Chemically Reactive Flows, Detonation and Combustion,  Facilities, Flow Visualization, Hypersonic Flow, Ignition, Impact and Compaction, Industrial Applications, Magnetohydrodynamics, Medical and Biological Applications, Nozzle Flow, Numerical Methods, Plasmas, Propulsion, Richtmyer-Meshkov Instability, Shock-Boundary Layer Interaction, Shock Propagation and Reflection, Shock Vortex Interaction, Shock Waves in Condensed Matter, Shock Waves in Multiphase Flow, as well as Shock Waves in Rarefield Flow. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 29 and individuals interes...

  11. Inferior vena cava obstruction and shock

    Megri Mohammed

    2018-01-01

    Full Text Available Shock is one of the most challenging life-threatening conditions with high mortality and morbidity; the outcomes are highly dependent on the early detection and management of the condition. Septic shock is the most common type of shock in the Intensive Care Unit. While not as common as other subsets of shock, obstructive shock is a significant subtype due to well defined mechanical and pathological causes, including tension pneumothorax, massive pulmonary embolism, and cardiac tamponade. We are presenting a patient with obstructive shock due to inferior vena cava obstruction secondary to extensive deep venous thrombosis. Chance of survival from obstructive shock in our patient was small; however, there was complete and immediate recovery after treatment of the obstruction on recognizing the affected vessels. This case alerts the practicing intensivist and the emergency medicine physician to consider occlusion of the great vessels other than the pulmonary artery or aorta as causes of obstructive shock.

  12. Shock dynamics in layered periodic media

    Ketcheson, David I.

    2012-01-01

    Solutions of constant-coeffcient nonlinear hyperbolic PDEs generically develop shocks, even if the initial data is smooth. Solutions of hyperbolic PDEs with variable coeffcients can behave very differently. We investigate formation and stability of shock waves in a one-dimensional periodic layered medium by a computational study of time-reversibility and entropy evolution. We find that periodic layered media tend to inhibit shock formation. For small initial conditions and large impedance variation, no shock formation is detected even after times much greater than the time of shock formation in a homogeneous medium. Furthermore, weak shocks are observed to be dynamically unstable in the sense that they do not lead to significant long-term entropy decay. We propose a characteristic condition for admissibility of shocks in heterogeneous media that generalizes the classical Lax entropy condition and accurately predicts the formation or absence of shocks in these media.

  13. Converging cylindrical shocks in ideal magnetohydrodynamics

    Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.

    2014-01-01

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=√(μ 0 /p 0 ) I/(2 π) where I is the current, μ 0 is the permeability, and p 0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field

  14. Converging cylindrical shocks in ideal magnetohydrodynamics

    Pullin, D. I.

    2014-09-01

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R = √μ0/p0 I/(2π) where I is the current, μ0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field then

  15. Converging cylindrical shocks in ideal magnetohydrodynamics

    Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, Ravi

    2014-01-01

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R = √μ0/p0 I/(2π) where I is the current, μ0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field then

  16. Converging cylindrical shocks in ideal magnetohydrodynamics

    Pullin, D. I. [Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, California 91125 (United States); Mostert, W.; Wheatley, V. [School of Mechanical and Mining Engineering, University of Queensland, Queensland 4072 (Australia); Samtaney, R. [Mechanical Engineering, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)

    2014-09-15

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=√(μ{sub 0}/p{sub 0}) I/(2 π) where I is the current, μ{sub 0} is the permeability, and p{sub 0} is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The

  17. Entropy jump across an inviscid shock wave

    Salas, Manuel D.; Iollo, Angelo

    1995-01-01

    The shock jump conditions for the Euler equations in their primitive form are derived by using generalized functions. The shock profiles for specific volume, speed, and pressure are shown to be the same, however density has a different shock profile. Careful study of the equations that govern the entropy shows that the inviscid entropy profile has a local maximum within the shock layer. We demonstrate that because of this phenomenon, the entropy, propagation equation cannot be used as a conservation law.

  18. Collisionless Electrostatic Shock Modeling and Simulation

    2016-10-21

    equations with piston -like boundary conditions gives a solution for the shock behavior. • Assumes cold upstream ions, therefore neglecting shock...temperature ratio (>10) – Wave Train Wavelength – Shock-Front Mach Number – Reflected Ion Beam Velocity Gathering Experiment Data – Double Plasma Device...experimental shock data. • Inconsistencies in published 1969 double -plasma device data hampered validation. Future Work: Extension to Moderately

  19. Shock waves in gas and plasma

    Niu, K.

    1996-01-01

    A shock wave is a discontinuous surface that connects supersonic flow with subsonic flow. After a shock wave, flow velocity is reduced, and pressure and temperature increase; entropy especially increases across a shock wave. Therefore, flow is in nonequilibrium, and irreversible processes occur inside the shock layer. The thickness of a shock wave in neutral gas is of the order of the mean free path of the fluid particle. A shock wave also appears in magnetized plasma. Provided that when the plasma flow is parallel to the magnetic field, a shock wave appears if the governing equation for velocity potential is in hyperbolic type in relation with the Mach number and the Alfven number. When the flow is perpendicular to the magnetic field, the Maxwell stress, in addition to the pressure, plays a role in the shock wave in plasma. When the plasma temperature is so high, as the plasma becomes collision-free, another type of shock wave appears. In a collision-free shock wave, gyromotions of electrons around the magnetic field lines cause the shock formation instead of collisions in a collision-dominant plasma or neutral gas. Regardless of a collision-dominant or collision-free shock wave, the fluid that passes through the shock wave is heated in addition to being compressed. In inertial confinement fusion, the fuel must be compressed. Really, implosion motion performs fuel compression. A shock wave, appearing in the process of implosion, compresses the fuel. The shock wave, however, heats the fuel more intensively, and it makes it difficult to compress the fuel further because high temperatures invite high pressure. Adiabatic compression of the fuel is the desired result during the implosion, without the formation of a shock wave. (Author)

  20. Electric shock and electrical fire specialty

    2011-02-01

    This book deals with electric shock and electrical fire, which is made up seven chapters. It describes of special measurement for electric shock and electrical fire. It mentions concretely about electrical fire analysis and precautionary measurement, electrical shock analysis cases, occurrence of static electricity and measurement, gas accident, analysis of equipment accident and precautionary measurement. The book is published to educate the measurement on electric shock and electrical fire by electrical safety technology education center in Korea Electrical Safety Corporation.

  1. Prenatal temperature shocks reduce cooperation

    Duchoslav, Jan

    2017-01-01

    Climate change has not only led to a sustained rise in mean global temperature over the past decades, but also increased the frequency of extreme weather events. This paper explores the effect of temperature shocks in utero on later-life taste for cooperation. Using historical climate data combined

  2. Shock Incarceration: Rehabilitation or Retribution?

    MacKenzie, Doris Layton; And Others

    1989-01-01

    Reviews Louisiana's shock incarceration program used as alternative to standard prison incarceration. Program involves short period of imprisonment in a "boot camp" type atmosphere followed by three phases of intensive parole supervision. Examines the program in regard to its rehabilitative potential and compares program elements to…

  3. Shock Mounting for Heavy Machines

    Thompson, A. R.

    1984-01-01

    Elastomeric bearings eliminate extraneous forces. Rocket thrust transmitted from motor to load cells via support that absorbs extraneous forces so they do not affect accuracy of thrust measurements. Adapter spoked cone fits over forward end of rocket motor. Shock mounting developed for rocket engines under test used as support for heavy machines, bridges, or towers.

  4. 2-Shock layered tuning campaign

    Masse, Laurent; Dittrich, T.; Khan, S.; Kyrala, G.; Ma, T.; MacLaren, S.; Ralph, J.; Salmonson, J.; Tipton, R.; Los Alamos Natl Lab Team; Lawrence Livermore Natl Lab Team

    2016-10-01

    The 2-Shock platform has been developed to maintain shell sphericity throughout the compression phase of an indirect-drive target implosion and produce a stagnating hot spot in a quasi 1D-like manner. A sub-scale, 1700 _m outer diameter, and thick, 200 _m, uniformly Silicon doped, gas-filled plastic capsule is driven inside a nominal size 5750 _m diameter ignition hohlraum. The hohlraum fill is near vacuum to reduce back-scatter and improve laser/drive coupling. A two-shock pulse of about 1 MJ of laser energy drives the capsule. The thick capsule prevents ablation front feed-through to the imploded core. This platform has demonstrated its efficiency to tune a predictable and reproducible 1-D implosion with a nearly round shape. It has been shown that the high foot performance was dominated by the local defect growth due to the ablation front instability and by the hohlraum radiation asymmetries. The idea here is to take advantage of this 2-Shock platform to design a 1D-like layered implosion and eliminates the deleterious effects of radiation asymmetries and ablation front instability growth. We present the design work and our first experimental results of this near one-dimensional 2-Shock layered design. This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344.

  5. Interstellar turbulence and shock waves

    Bykov, A.M.

    1982-01-01

    Random deflections of shock fronts propagated through the turbulent interstellar medium can produce the strong electro-density fluctuations on scales l> or approx. =10 13 cm inferred from pulsar radio scintillations. The development of turbulence in the hot-phase ISM is discussed

  6. Nonlinearity, Conservation Law and Shocks

    However, genuine nonlinearity is always present in an ideal gas. The conservation form of the equation (25) brings in shocks which cut off the growing part of the amplitUde as shown in. Figure 15. Acknowledgements. The author sincerely thanks the two referees whose valuable comments led to an improvement of the ...

  7. Model for Shock Wave Chaos

    Kasimov, Aslan R.

    2013-03-08

    We propose the following model equation, ut+1/2(u2−uus)x=f(x,us) that predicts chaotic shock waves, similar to those in detonations in chemically reacting mixtures. The equation is given on the half line, x<0, and the shock is located at x=0 for any t≥0. Here, us(t) is the shock state and the source term f is taken to mimic the chemical energy release in detonations. This equation retains the essential physics needed to reproduce many properties of detonations in gaseous reactive mixtures: steady traveling wave solutions, instability of such solutions, and the onset of chaos. Our model is the first (to our knowledge) to describe chaos in shock waves by a scalar first-order partial differential equation. The chaos arises in the equation thanks to an interplay between the nonlinearity of the inviscid Burgers equation and a novel forcing term that is nonlocal in nature and has deep physical roots in reactive Euler equations.

  8. EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY AS ...

    Objective To evaluate extracorporeal shock wave lithotripsy (ESWL) as a monotherapy for urolithiasis in patients with solitary kidney and to determine the factors that may affect its results. Patients and Methods Using the Dornier MFL 5000 lithotriptor, 106 patients with solitary kidney (80 men and 26 women) were treated for ...

  9. Shock formation within sonoluminescence bubbles

    Vuong, V.Q.; Szeri, A.J.; Young, D.A.

    1999-01-01

    A strong case has been made by several authors that sharp, spherically symmetric shocks converging on the center of a spherical bubble driven by a strong acoustic field give rise to rapid compression and heating that produces the brief flash of light known as sonoluminescence. The formation of such shocks is considered. It is found that, although at the main collapse the bubble wall does indeed launch an inwardly-traveling compression wave, and although the subsequent reflection of the wave at the bubble center produces a very rapid temperature peak, the wave is prevented from steepening into a sharp shock by an adverse gradient in the sound speed caused by heat transfer. It is shown that the mathematical characteristics of the flow can be prevented from accumulating into a shock front by this adverse sound speed gradient. A range of results is presented for a variety of bubble ambient radii and sound field amplitudes suggested by experiments. The time scale of the peak temperature in the bubble is set by the dynamics of the compression wave: this is typically in the range 100 - 300 ps (FWHM) in concert with recent measurements of the sonoluminescence pulse width. copyright 1999 American Institute of Physics

  10. Model for Shock Wave Chaos

    Kasimov, Aslan R.; Faria, Luiz; Rosales, Rodolfo R.

    2013-01-01

    : steady traveling wave solutions, instability of such solutions, and the onset of chaos. Our model is the first (to our knowledge) to describe chaos in shock waves by a scalar first-order partial differential equation. The chaos arises in the equation

  11. Studying shocks in model astrophysical flows

    Chakrabarti, S.K.

    1989-01-01

    We briefly discuss some properties of the shocks in the existing models for quasi two-dimensional astrophysical flows. All of these models which allow the study of shock analytically have some unphysical characteristics due to inherent assumptions made. We propose a hybrid model for a thin flow which has fewer unpleasant features and is suitable for the study of shocks. (author). 5 refs

  12. Shock waves in relativistic nuclear matter, I

    Gleeson, A.M.; Raha, S.

    1979-02-01

    The relativistic Rankine-Hugoniot relations are developed for a 3-dimensional plane shock and a 3-dimensional oblique shock. Using these discontinuity relations together with various equations of state for nuclear matter, the temperatures and the compressibilities attainable by shock compression for a wide range of laboratory kinetic energy of the projectile are calculated. 12 references

  13. The microphysics of collisionless shock waves

    Marcowith, Alexandre; Bret, Antoine; Bykov, Andrei

    2016-01-01

    Collisionless shocks, that is shocks mediated by electromagnetic processes, are customary in space physics and in astrophysics. They are to be found in a great variety of objects and environments: magnetospheric and heliospheric shocks, supernova remnants, pulsar winds and their nebulæ, active ga...

  14. Permeability enhancement by shock cooling

    Griffiths, Luke; Heap, Michael; Reuschlé, Thierry; Baud, Patrick; Schmittbuhl, Jean

    2015-04-01

    The permeability of an efficient reservoir, e.g. a geothermal reservoir, should be sufficient to permit the circulation of fluids. Generally speaking, permeability decreases over the life cycle of the geothermal system. As a result, is usually necessary to artificially maintain and enhance the natural permeability of these systems. One of the methods of enhancement -- studied here -- is thermal stimulation (injecting cold water at low pressure). This goal of this method is to encourage new thermal cracks within the reservoir host rocks, thereby increasing reservoir permeability. To investigate the development of thermal microcracking in the laboratory we selected two granites: a fine-grained (Garibaldi Grey granite, grain size = 0.5 mm) and a course-grained granite (Lanhelin granite, grain size = 2 mm). Both granites have an initial porosity of about 1%. Our samples were heated to a range of temperatures (100-1000 °C) and were either cooled slowly (1 °C/min) or shock cooled (100 °C/s). A systematic microstructural (2D crack area density, using standard stereological techniques, and 3D BET specific surface area measurements) and rock physical property (porosity, P-wave velocity, uniaxial compressive strength, and permeability) analysis was undertaken to understand the influence of slow and shock cooling on our reservoir granites. Microstructurally, we observe that the 2D crack surface area per unit volume and the specific surface area increase as a result of thermal stressing, and, for the same maximum temperature, crack surface area is higher in the shock cooled samples. This observation is echoed by our rock physical property measurements: we see greater changes for the shock cooled samples. We can conclude that shock cooling is an extremely efficient method of generating thermal microcracks and modifying rock physical properties. Our study highlights that thermal treatments are likely to be an efficient method for the "matrix" permeability enhancement of

  15. Click-Evoked Auditory Efferent Activity: Rate and Level Effects.

    Boothalingam, Sriram; Kurke, Julianne; Dhar, Sumitrajit

    2018-05-07

    There currently are no standardized protocols to evaluate auditory efferent function in humans. Typical tests use broadband noise to activate the efferents, but only test the contralateral efferent pathway, risk activating the middle ear muscle reflex (MEMR), and are laborious for clinical use. In an attempt to develop a clinical test of bilateral auditory efferent function, we have designed a method that uses clicks to evoke efferent activity, obtain click-evoked otoacoustic emissions (CEOAEs), and monitor MEMR. This allows for near-simultaneous estimation of cochlear and efferent function. In the present study, we manipulated click level (60, 70, and 80 dB peak-equivalent sound pressure level [peSPL]) and rate (40, 50, and 62.5 Hz) to identify an optimal rate-level combination that evokes measurable efferent modulation of CEOAEs. Our findings (n = 58) demonstrate that almost all click levels and rates used caused significant inhibition of CEOAEs, with a significant interaction between level and rate effects. Predictably, bilateral activation produced greater inhibition compared to stimulating the efferents only in the ipsilateral or contralateral ear. In examining the click rate-level effects during bilateral activation in greater detail, we observed a 1-dB inhibition of CEOAE level for each 10-dB increase in click level, with rate held constant at 62.5 Hz. Similarly, a 10-Hz increase in rate produced a 0.74-dB reduction in CEOAE level, with click level held constant at 80 dB peSPL. The effect size (Cohen's d) was small for either monaural condition and medium for bilateral, faster-rate, and higher-level conditions. We were also able to reliably extract CEOAEs from efferent eliciting clicks. We conclude that clicks can indeed be profitably employed to simultaneously evaluate cochlear health using CEOAEs as well as their efferent modulation. Furthermore, using bilateral clicks allows the evaluation of both the crossed and uncrossed elements of the auditory

  16. Assessment of visual disability using visual evoked potentials.

    Jeon, Jihoon; Oh, Seiyul; Kyung, Sungeun

    2012-08-06

    The purpose of this study is to validate the use of visual evoked potential (VEP) to objectively quantify visual acuity in normal and amblyopic patients, and determine if it is possible to predict visual acuity in disability assessment to register visual pathway lesions. A retrospective chart review was conducted of patients diagnosed with normal vision, unilateral amblyopia, optic neuritis, and visual disability who visited the university medical center for registration from March 2007 to October 2009. The study included 20 normal subjects (20 right eyes: 10 females, 10 males, ages 9-42 years), 18 unilateral amblyopic patients (18 amblyopic eyes, ages 19-36 years), 19 optic neuritis patients (19 eyes: ages 9-71 years), and 10 patients with visual disability having visual pathway lesions. Amplitude and latencies were analyzed and correlations with visual acuity (logMAR) were derived from 20 normal and 18 amblyopic subjects. Correlation of VEP amplitude and visual acuity (logMAR) of 19 optic neuritis patients confirmed relationships between visual acuity and amplitude. We calculated the objective visual acuity (logMAR) of 16 eyes from 10 patients to diagnose the presence or absence of visual disability using relations derived from 20 normal and 18 amblyopic eyes. Linear regression analyses between amplitude of pattern visual evoked potentials and visual acuity (logMAR) of 38 eyes from normal (right eyes) and amblyopic (amblyopic eyes) subjects were significant [y = -0.072x + 1.22, x: VEP amplitude, y: visual acuity (logMAR)]. There were no significant differences between visual acuity prediction values, which substituted amplitude values of 19 eyes with optic neuritis into function. We calculated the objective visual acuity of 16 eyes of 10 patients to diagnose the presence or absence of visual disability using relations of y = -0.072x + 1.22 (-0.072). This resulted in a prediction reference of visual acuity associated with malingering vs. real

  17. SOMATOSENSORY EVOKED POTENTIALS IN DIABETES MELLITUS TYPE - 2

    Rekha

    2015-10-01

    Full Text Available Diabetes mellitus is the most common metabolic disorder affecting majority of population. It is estimated that over 400 million people throughout the world have diabetes. It has progressed to be a pandemic from an epidemic causing morbidity and mortality in the population. Among the many complications of diabetes, diabetic neuropathies contribute majorly to the morbidity associated with the disease. Axonal conduction is affected by elevated levels of protein kinase c causing neuronal ischemia; decreased ce llular myoinositol affecting sodium potassium ATPase pump leads to decreased nerve conduction; Somatosensory E voked P otentials (SSEPs reflect the activity of somatosensory pathways mediated through the dorsal columns of the spinal cord and the specific so matosensory cortex. Recording of Somatosensory Evoked Potentials in diabetics is done to assess the sensory involvement of spinal cord. Presence of SEPs provides clear evidence for axonal continuity and by using different stimulation sites, the rate of reg eneration can be determined. Both onset and peak latencies of all SEP components are prolonged in patients with diabetes. Present study is done to compare somatosensory evoked potentials in diabetics and normal subjects. MATERIALS AND METHOD S: The present study was undertaken at the Upgraded Department of Physiology, Osmania Medical College, Koti, Hyderabad. The study was conducted on subjects, both male and female in the age group of 45 to 55 years, suffering from type II diabetes excluding other neurologi cal disorders. Non - invasive method of estimation of nerve conduction studies using SFEMG/EP — Electromyography or evoked potential system (Nicolet systems — USA using surface electrodes with automated computerized monitor attached with printer is used. RESUL TS : ANOVA showed statistically significant N9 latency (right & left sides. Latencies of all the components of SSEPs were more significant than amplitudes in Diabetic

  18. Vestibular myogenic and acoustical brainstem evoked potentials in neurological practice

    O. S. Korepina

    2012-01-01

    Full Text Available Along with the inspection of acoustical cortex and brainstem EP in neurologic, otoneurologic and audiologic practice recently start to use so-called vestibular evoked myogenic potentials (VEMP. It is shown, that at ear stimulation by a loud sound and record of sterno-cleidomastoid contraction is possible to estimate function of the inferior vestibular nerve and vestibulospinal pathways, a sacculo-cervical reflex. In article some methodical and clinical questions of application of these kinds are presented. Combine research acoustic brainstem EP and VEMP allows to confirm effectively lesions of acoustical and vestibular ways at brainstem. The conclusion becomes, that this kind of inspection is important for revealing demielinisation and defeats in vestibulospinal tract, that quite often happens at MS, and at estimation of efficiency of treatment

  19. Auditory evoked field measurement using magneto-impedance sensors

    Wang, K., E-mail: o-kabou@echo.nuee.nagoya-u.ac.jp; Tajima, S.; Song, D.; Uchiyama, T. [Graduate School of Engineering, Nagoya University, Nagoya (Japan); Hamada, N.; Cai, C. [Aichi Steel Corporation, Tokai (Japan)

    2015-05-07

    The magnetic field of the human brain is extremely weak, and it is mostly measured and monitored in the magnetoencephalography method using superconducting quantum interference devices. In this study, in order to measure the weak magnetic field of the brain, we constructed a Magneto-Impedance sensor (MI sensor) system that can cancel out the background noise without any magnetic shield. Based on our previous studies of brain wave measurements, we used two MI sensors in this system for monitoring both cerebral hemispheres. In this study, we recorded and compared the auditory evoked field signals of the subject, including the N100 (or N1) and the P300 (or P3) brain waves. The results suggest that the MI sensor can be applied to brain activity measurement.

  20. Visual evoked potentials of mildly mentally retarded and control children.

    Gasser, T; Pietz, J; Schellberg, D; Köhler, W

    1988-10-01

    Visual evoked potentials (VEPs) were recorded from 25 10- to 13-year-old mildly mentally retarded children and compared with those from 31 control children of the same age-range. Correlations of VEPs with age were weak, but a relationship between VEPs and IQ was demonstrated for the control group. The retarded group had significantly longer latencies and higher amplitude peaks than the control group, with the differences occurring primarily over non-specific cortex and for secondary components. Analysis also showed that the retarded group were neurophysiologically heterogeneous. Since the same children had been analyzed earlier by quantitative EEG methods, comparisons are made with respect to these two methods of investigating brain function.

  1. Visual evoked potentials in neuromyelitis optica and its spectrum disorders.

    Ringelstein, Marius; Kleiter, Ingo; Ayzenberg, Ilya; Borisow, Nadja; Paul, Friedemann; Ruprecht, Klemens; Kraemer, Markus; Cohn, Eva; Wildemann, Brigitte; Jarius, Sven; Hartung, Hans-Peter; Aktas, Orhan; Albrecht, Philipp

    2014-04-01

    Optic neuritis (ON) is a key feature of neuromyelitis optica (NMO). Recently, NMO patients of predominantly Afro-Brazilian origin were evaluated by visual evoked potentials (VEPs) and showed marked amplitude reductions. Here, we analyzed VEPs in a predominantly Caucasian cohort, consisting of 43 patients with definite NMO, 18 with anti-aquaporin (AQP) 4 antibody-seropositive NMO spectrum disorders and 61 matched healthy controls. We found reduced amplitudes in only 12.3%, prolonged latencies in 41.9% and a lack of response in 14.0% of NMO eyes. Delayed P100 latencies in eyes without prior ON suggested this was a subclinical affection. The data indicate heterogenous patterns in NMO, warranting further investigation.

  2. Visual evoked potentials and selective attention to points in space

    Van Voorhis, S.; Hillyard, S. A.

    1977-01-01

    Visual evoked potentials (VEPs) were recorded to sequences of flashes delivered to the right and left visual fields while subjects responded promptly to designated stimuli in one field at a time (focused attention), in both fields at once (divided attention), or to neither field (passive). Three stimulus schedules were used: the first was a replication of a previous study (Eason, Harter, and White, 1969) where left- and right-field flashes were delivered quasi-independently, while in the other two the flashes were delivered to the two fields in random order (Bernoulli sequence). VEPs to attended-field stimuli were enhanced at both occipital (O2) and central (Cz) recording sites under all stimulus sequences, but different components were affected at the two scalp sites. It was suggested that the VEP at O2 may reflect modality-specific processing events, while the response at Cz, like its auditory homologue, may index more general aspects of selective attention.

  3. Conscious wireless electroretinogram and visual evoked potentials in rats.

    Jason Charng

    Full Text Available The electroretinogram (ERG, retina and visual evoked potential (VEP, brain are widely used in vivo tools assaying the integrity of the visual pathway. Current recordings in preclinical models are conducted under anesthesia, which alters neural physiology and contaminates responses. We describe a conscious wireless ERG and VEP recording platform in rats. Using a novel surgical technique to chronically implant electrodes subconjunctivally on the eye and epidurally over the visual cortex, we are able to record stable and repeatable conscious ERG and VEP signals over at least 1 month. We show that the use of anaesthetics, necessary for conventional ERG and VEP measurements, alters electrophysiology recordings. Conscious visual electrophysiology improves the viability of longitudinal studies by eliminating complications associated with repeated anaesthesia. It will also enable uncontaminated assessment of drug effects, allowing the eye to be used as an effective biomarker of the central nervous system.

  4. Suicide attempts, platelet monoamine oxidase and the average evoked response

    Buchsbaum, M.S.; Haier, R.J.; Murphy, D.L.

    1977-01-01

    The relationship between suicides and suicide attempts and two biological measures, platelet monoamine oxidase levels (MAO) and average evoked response (AER) augmenting was examined in 79 off-medication psychiatric patients and in 68 college student volunteers chosen from the upper and lower deciles of MAO activity levels. In the patient sample, male individuals with low MAO and AER augmenting, a pattern previously associated with bipolar affective disorders, showed a significantly increased incidence of suicide attempts in comparison with either non-augmenting low MAO or high MAO patients. Within the normal volunteer group, all male low MAO probands with a family history of suicide or suicide attempts were AER augmenters themselves. Four completed suicides were found among relatives of low MAO probands whereas no high MAO proband had a relative who committed suicide. These findings suggest that the combination of low platelet MAO activity and AER augmenting may be associated with a possible genetic vulnerability to psychiatric disorders. (author)

  5. Inappropriate shocks in the subcutaneous ICD

    Olde Nordkamp, Louise R A; Brouwer, Tom F; Barr, Craig

    2015-01-01

    shocks have been reported. METHODS: We analyzed the incidence, predictors and management of inappropriate shocks in the EFFORTLESS S-ICD Registry, which collects S-ICD implantation information and follow-up data from clinical centers in Europe and New Zealand. RESULTS: During a follow-up of 21 ± 13...... xyphoid to V6) reduced the risk. Reprogramming or optimization of SVT treatment after the first clinical event of inappropriate shock was successful in preventing further inappropriate shocks for cardiac oversensing and SVT events. CONCLUSIONS: Inappropriate shocks, mainly due to cardiac oversensing...

  6. Evoked bioelectrical brain activity following exposure to ionizing radiation.

    Loganovsky, K; Kuts, K

    2017-12-01

    The article provides an overview of modern physiological evidence to support the hypothesis on cortico limbic sys tem dysfunction due to the hippocampal neurogenesis impairment as a basis of the brain interhemispheric asym metry and neurocognitive deficit after radiation exposure. The importance of the research of both evoked poten tials and fields as a highly sensitive and informative method is emphasized.Particular attention is paid to cerebral sensor systems dysfunction as a typical effect of ionizing radiation. Changes in functioning of the central parts of sensory analyzers of different modalities as well as the violation of brain integrative information processes under the influence of small doses of ionizing radiation can be critical when determining the radiation risks of space flight. The possible long term prospects for manned flights into space, including to Mars, given the effects identified are discussed. Potential risks to the central nervous system during space travel comprise cognitive functions impairment, including the volume of short term memory short ening, impaired motor functions, behavioral changes that could affect human performance and health. The remote risks for CNS are considered to be the following possible neuropsychiatric disorders: accelerated brain aging, Alzheimer's disease and other types of dementia. The new radiocerebral dose dependent effect, when applied cog nitive auditory evoked potentials P300 technique with a possible threshold dose of 0.05 Gy, manifesting in a form of disruption of information processing in the Wernicke's area is under discussion. In order to identify neurophys iological biological markers of ionizing radiation further international researches with adequate dosimetry support are necessary. K. Loganovsky, K. Kuts.

  7. Perpendicular relativistic shocks in magnetized pair plasma

    Plotnikov, Illya; Grassi, Anna; Grech, Mickael

    2018-04-01

    Perpendicular relativistic (γ0 = 10) shocks in magnetized pair plasmas are investigated using two dimensional Particle-in-Cell simulations. A systematic survey, from unmagnetized to strongly magnetized shocks, is presented accurately capturing the transition from Weibel-mediated to magnetic-reflection-shaped shocks. This transition is found to occur for upstream flow magnetizations 10-3 10-2, it leaves place to a purely electromagnetic precursor following from the strong emission of electromagnetic waves at the shock front. Particle acceleration is found to be efficient in weakly magnetized perpendicular shocks in agreement with previous works, and is fully suppressed for σ > 10-2. Diffusive Shock Acceleration is observed only in weakly magnetized shocks, while a dominant contribution of Shock Drift Acceleration is evidenced at intermediate magnetizations. The spatial diffusion coefficients are extracted from the simulations allowing for a deeper insight into the self-consistent particle kinematics and scale with the square of the particle energy in weakly magnetized shocks. These results have implications for particle acceleration in the internal shocks of AGN jets and in the termination shocks of Pulsar Wind Nebulae.

  8. Initial conditions of radiative shock experiments

    Kuranz, C. C.; Drake, R. P.; Krauland, C. M.; Marion, D. C.; Grosskopf, M. J.; Rutter, E.; Torralva, B.; Holloway, J. P.; Bingham, D.; Goh, J.; Boehly, T. R.; Sorce, A. T.

    2013-01-01

    We performed experiments at the Omega Laser Facility to characterize the initial, laser-driven state of a radiative shock experiment. These experiments aimed to measure the shock breakout time from a thin, laser-irradiated Be disk. The data are then used to inform a range of valid model parameters, such as electron flux limiter and polytropic γ, used when simulating radiative shock experiments using radiation hydrodynamics codes. The characterization experiment and the radiative shock experiment use a laser irradiance of ∼7 × 10 14 W cm −2 to launch a shock in the Be disk. A velocity interferometer and a streaked optical pyrometer were used to infer the amount of time for the shock to move through the Be disk. The experimental results were compared with simulation results from the Hyades code, which can be used to model the initial conditions of a radiative shock system using the CRASH code

  9. Exploratory laser-driven shock wave studies

    Solem, J.C.; Veeser, L.R.

    1977-11-01

    We show the results of a feasibility study for investigating shock structure and for measuring equation-of-state parameters using high-energy, short-pulse lasers. We discuss the temporal and spatial structure of the luminosity from laser-driven shock unloading in aluminum foils. We demonstrate that shock velocity can be measured by observing the time interval between shock emergence across two thicknesses and show data for shocks of 1.3 and 2.1 Mbar. The fact that we observe shock fronts cleanly breaking through steps as small as 3 μm indicates that the shock front thickness is very small in the few megabar region; this is the first experimental verification that these fronts are not more than a few micrometers thick. We present approximate measurements of free-surface velocity. Finally, we speculate on the use of these techniques to obtain detailed equation-of-state data

  10. Shock-induced chemistry in organic materials

    Dattelbaum, Dana M [Los Alamos National Laboratory; Sheffield, Steve [Los Alamos National Laboratory; Engelke, Ray [Los Alamos National Laboratory; Manner, Virginia [Los Alamos National Laboratory; Chellappa, Raja [Los Alamos National Laboratory; Yoo, Choong - Shik [WASHINGTON STATE UNIV

    2011-01-20

    The combined 'extreme' environments of high pressure, temperature, and strain rates, encountered under shock loading, offer enormous potential for the discovery of new paradigms in chemical reactivity not possible under more benign conditions. All organic materials are expected to react under these conditions, yet we currently understand very little about the first bond-breaking steps behind the shock front, such as in the shock initiation of explosives, or shock-induced reactivity of other relevant materials. Here, I will present recent experimental results of shock-induced chemistry in a variety of organic materials under sustained shock conditions. A comparison between the reactivity of different structures is given, and a perspective on the kinetics of reaction completion under shock drives.

  11. Experimental methods of shock wave research

    Seiler, Friedrich

    2016-01-01

    This comprehensive and carefully edited volume presents a variety of experimental methods used in Shock Waves research. In 14 self contained chapters this 9th volume of the “Shock Wave Science and Technology Reference Library” presents the experimental methods used in Shock Tubes, Shock Tunnels and Expansion Tubes facilities. Also described is their set-up and operation. The uses of an arc heated wind tunnel and a gun tunnel are also contained in this volume. Whenever possible, in addition to the technical description some typical scientific results obtained using such facilities are described. Additionally, this authoritative book includes techniques for measuring physical properties of blast waves and laser generated shock waves. Information about active shock wave laboratories at different locations around the world that are not described in the chapters herein is given in the Appendix, making this book useful for every researcher involved in shock/blast wave phenomena.

  12. Motion of shocks through interplanetary streams

    Burlaga, L.F.; Scudder, J.D.

    1975-01-01

    A model for the motion of flare-generated shocks through interplanetary streams is presented, illustrating the effects of a stream-shock interaction on the shock strength and geometry. It is a gas dynamic calculation based on Whitham's method and on an empirical approximation for the relevant characteristics of streams. The results show that the Mach number of a shock can decrease appreciably to near unity in the interaction region ahead of streams and that the interaction of a spherically symmetric shock with a spiral-shaped corotating stream can cause significant distortions of the initial shock front geometry. The geometry of the February 15--16, 1967, shock discussed by Lepping and Chao (1972) is qualitatively explained by this model

  13. Do oil shocks predict economic policy uncertainty?

    Rehman, Mobeen Ur

    2018-05-01

    Oil price fluctuations have influential role in global economic policies for developed as well as emerging countries. I investigate the role of international oil prices disintegrated into structural (i) oil supply shock, (ii) aggregate demand shock and (iii) oil market specific demand shocks, based on the work of Kilian (2009) using structural VAR framework on economic policies uncertainty of sampled markets. Economic policy uncertainty, due to its non-linear behavior is modeled in a regime switching framework with disintegrated structural oil shocks. Our results highlight that Indian, Spain and Japanese economic policy uncertainty responds to the global oil price shocks, however aggregate demand shocks fail to induce any change. Oil specific demand shocks are significant only for China and India in high volatility state.

  14. Shock Wave Dynamics in Weakly Ionized Plasmas

    Johnson, Joseph A., III

    1999-01-01

    An investigation of the dynamics of shock waves in weakly ionized argon plasmas has been performed using a pressure ruptured shock tube. The velocity of the shock is observed to increase when the shock traverses the plasma. The observed increases cannot be accounted for by thermal effects alone. Possible mechanisms that could explain the anomalous behavior include a vibrational/translational relaxation in the nonequilibrium plasma, electron diffusion across the shock front resulting from high electron mobility, and the propagation of ion-acoustic waves generated at the shock front. Using a turbulence model based on reduced kinetic theory, analysis of the observed results suggest a role for turbulence in anomalous shock dynamics in weakly ionized media and plasma-induced hypersonic drag reduction.

  15. Sex differences in the jealousy-evoking nature of a rival's body build

    Dijkstra, Pieternel; Buunk, Abraham (Bram)

    This study among 185 college students showed that potential rivals with a relatively low waist-to-hip ratio (WHR) evoked more jealousy in women than in men. In contrast, rivals with a relatively high shoulder-to-hip ratio (SHR) evoked more jealousy in men than in women, particularly when the rival

  16. Do Puzzle Pieces and Autism Puzzle Piece Logos Evoke Negative Associations?

    Gernsbacher, Morton Ann; Raimond, Adam R.; Stevenson, Jennifer L.; Boston, Jilana S.; Harp, Bev

    2018-01-01

    Puzzle pieces have become ubiquitous symbols for autism. However, puzzle-piece imagery stirs debate between those who support and those who object to its use because they believe puzzle-piece imagery evokes negative associations. Our study empirically investigated whether puzzle pieces evoke negative associations in the general public.…

  17. Gender differences in rival characteristics that evoke jealousy in response to emotional versus sexual infidelity

    Buunk, Abraham (Bram); Dijkstra, Pieternel

    2004-01-01

    Previous research has shown that in men jealousy is evoked more by a rival's status-related characteristics than in women, whereas in women jealousy is evoked more by a rival's physical attractiveness than in men. The present study examined whether the occurrence of this gender difference depends

  18. Conduction velocity of the human spinothalamic tract as assessed by laser evoked potentials

    Cruccu, G.; Iannetti, G. D.; Agostino, R.

    2000-01-01

    To study the conduction velocity of the spinothalamic tract (STT) we delivered CO2 laser pulses, evoking pinprick sensations, to the skin overlying the vertebral spinous processes at different spinal levels from C5 to T10 and recorded evoked potentials (LEPs) in 15 healthy human subjects...

  19. The Relationship of Visual Evoked Potential Asymmetries to the Performance of Sonar Operators

    1981-08-11

    also been related to EP variability. Schizophrenic adults and patients with Korsakoff’s Syndrome have shown higher evoked potential variability than...average evoked response in Korsakoff patients. J. Psychiatry Res. 6: 253-260, 1969. Santoro, T. and D. Fender. Rules for the perception of

  20. Study on Reflected Shock Wave/Boundary Layer Interaction in a Shock Tube

    Kim, Dong Wook; Kim, Tae Ho; Kim, Heuy Dong [Andong Nat’l Univ., Andong (Korea, Republic of)

    2017-07-15

    The interaction between a shock wave and a boundary layer causes boundary layer separation, shock train, and in some cases, strong unsteadiness in the flow field. Such a situation is also observed in a shock tube, where the reflected shock wave interacts with the unsteady boundary layer. However, only a few studies have been conducted to investigate the shock train phenomenon in a shock tube. In the present study, numerical studies were conducted using the two-dimensional axisymmetric domain of a shock tube, and compressible Navier-Stokes equations were solved to clarify the flow characteristics of shock train phenomenon inside a shock tube. A detailed wave diagram was developed based on the present computational results, which were validated with existing experimental data.

  1. [Intraoperative pain stimuli change somatosensory evoked potentials, but not auditory evoked potentials during isoflurane/nitrous oxide anesthesia].

    Rundshagen, I; Kochs, E; Bischoff, P; Schulte am Esch, J

    1997-10-01

    Evoked potentials are used for intraoperative monitoring to assess changes of cerebral function. This prospective randomised study assesses the influence of surgical stimulation on midlatency components of somatosensory (SEPs) and auditory evoked potentials (AEPs) in anaesthetised patients. After approval of the Ethics Committee and written informed consent 36 orthopaedic patients (34 +/- 15 y, 73 +/- 14 kg. 1.71 +/- 0.07 m, ASA I-II) were randomly included in the study. Anaesthesia was induced with 1.5 micrograms/kg fentanyl, 0.3 mg/kg etomidate and 0.1 mg/kg vecuronium. The lungs were intubated and patients normoventilated in steady state anaesthesia with isoflurane (end-tidal 0.6%) and 66% nitrous oxide. 18 patients (group 1) were assigned to the SEP group: median nerve stimulation, recording at Erb, C 6 and the contralateral somatosensory cortex (N20, P25, N35) vs Fz. AEPs were recorded in group 2 (n = 18): binaural stimulation, recording at Cz versus linked mastoid (V, Na, Pa, Nb). Recordings were performed during 30 min before the start of surgery (baseline: BL), at skin incision (SURG1) and at the preparation of the periost (SURG2). Heart rate, mean arterial blood pressure, oxygen saturation, endtidal pCO2 and isoflurane (PetISO) concentrations were registered simultaneously. Data were analysed by one-way analysis of variance. Post hoc comparison were made by Mann-Whitney U-Wilcoxon Rank Sum Test with p beats/min) to SURG2 (76 +/- 12 beats/min). Increases of amplitudes of midlatency SEP amplitudes indicate increased nociceptive signal transmission which is not blunted by isoflurane-nitrous oxide anaesthesia. In contrast, unchanged AEPs indicate adequate levels of the hypnotic components of anaesthesia.

  2. Insight into magnetorheological shock absorbers

    Gołdasz, Janusz

    2015-01-01

    This book deals with magnetorheological fluid theory, modeling and applications of automotive magnetorheological dampers. On the theoretical side a review of MR fluid compositions and key factors affecting the characteristics of these fluids is followed by a description of existing applications in the area of vibration isolation and flow-mode shock absorbers in particular. As a majority of existing magnetorheological devices operates in a so-called flow mode a critical review is carried out in that regard. Specifically, the authors highlight common configurations of flow-mode magnetorheological shock absorbers, or so-called MR dampers that have been considered by the automotive industry for controlled chassis applications. The authors focus on single-tube dampers utilizing a piston assembly with one coil or multiple coils and at least one annular flow channel in the piston.

  3. Magnetohydrodynamic shocks in molecular clouds

    Chernoff, D.F.

    1985-01-01

    Part one develops the mathematical and physical theory of one-dimensional, time-independent subalfvenic flow in partially ionized gas with magnetic fields, for application to shocks in molecular clouds. Unlike normal gas-dynamic shocks, the neutral flow may be continuous and cool if the gas radiates efficiently and does not self-ionize. Analytic solutions are given in the limit that the neutral gas is either adiabatic or isothermal (cold). Numerical techniques are developed and applied to find the neutral flow under general circumstances. Part two extends the theory and results of part one in three ways: (1) to faster, superalfvenic flow, (2) to complex gases containing heavy charged particles (grains) in addition to ions, containing heavy charged particles (grains) in addition to ions, electrons and neutrals, and (3) to the entire range in (Omega tau), the ratio of charged particle damping time to gyroperiod, expected in gas flows in molecular clouds

  4. Odor-evoked inhibition of olfactory sensory neurons drives olfactory perception in Drosophila.

    Cao, Li-Hui; Yang, Dong; Wu, Wei; Zeng, Xiankun; Jing, Bi-Yang; Li, Meng-Tong; Qin, Shanshan; Tang, Chao; Tu, Yuhai; Luo, Dong-Gen

    2017-11-07

    Inhibitory response occurs throughout the nervous system, including the peripheral olfactory system. While odor-evoked excitation in peripheral olfactory cells is known to encode odor information, the molecular mechanism and functional roles of odor-evoked inhibition remain largely unknown. Here, we examined Drosophila olfactory sensory neurons and found that inhibitory odors triggered outward receptor currents by reducing the constitutive activities of odorant receptors, inhibiting the basal spike firing in olfactory sensory neurons. Remarkably, this odor-evoked inhibition of olfactory sensory neurons elicited by itself a full range of olfactory behaviors from attraction to avoidance, as did odor-evoked olfactory sensory neuron excitation. These results indicated that peripheral inhibition is comparable to excitation in encoding sensory signals rather than merely regulating excitation. Furthermore, we demonstrated that a bidirectional code with both odor-evoked inhibition and excitation in single olfactory sensory neurons increases the odor-coding capacity, providing a means of efficient sensory encoding.

  5. Study on change of multi-modally evoked potentials in nasopharyngeal carcinoma patients after radiotherapy

    Qin Ling; Chen Jiaxin; Zhang Lixiang; Wang Tiejian; Han Min; Lu Xiaoling

    2001-01-01

    Objective: To investigate possible changes of multi-modally evoked potentials in nasopharyngeal carcinoma patients after radiotherapy. Methods: Altogether 48 nasopharyngeal carcinoma patients receiving primary conventional external beam irradiation were examined before and after radiotherapy to determine their brainstem auditory-evoked potential (BAEP), short-latency somatosensory-evoked potential (SLSEP) and pattern reversal visual-evoked potential (PRVEP). Results: In comparison with the conditions before radiotherapy, in different periods after radiotherapy abnormal peak latency and interval latency difference were found in BAEP, SLSEP and PRVEP. Conclusion: Nasopharyngeal carcinoma after radiotherapy may cause abnormal function of nerve conduction in early periods, which can be showed by BAEP, SLSEP, PRVEP, and injury can be timely detected if the three evoked potentials are used together. Thus authors suggest BAEP, SLSEP, PRVEP should be examined in nasopharyngeal carcinoma patients during and after the radiotherapy so as to find early damage in auditory somatosensory and visual conduction pathways

  6. The involuntary nature of music-evoked autobiographical memories in Alzheimer's disease.

    El Haj, Mohamad; Fasotti, Luciano; Allain, Philippe

    2012-03-01

    The main objective of this paper was to examine the involuntary nature of music-evoked autobiographical memories. For this purpose, young adults, older adults, and patients with a clinical diagnosis of probable Alzheimer's disease (AD) were asked to remember autobiographical events in two conditions: after being exposed to their own chosen music, and in silence. Compared to memories evoked in silence, memories evoked in the "Music" condition were found to be more specific, accompanied by more emotional content and impact on mood, and retrieved faster. In addition, these memories engaged less executive processes. Thus, with all these characteristics and the fact that they are activated by a perceptual cue (i.e., music), music-evoked autobiographic memories have all the features to be considered as involuntary memories. Our paper reveals several characteristics of music-evoked autobiographical memories in AD patients and offers a theoretical background for this phenomenon. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. MHD shocks in the ISM

    Chernoff, D. F.; Hollenbach, David J.; Mckee, Christopher F.

    1990-01-01

    Researchers survey shock solutions of a partially ionized gas with a magnetic field. The gas is modeled by interacting neutral, ion, electron and charged grain components. They employ a small neutral-ion chemical network to follow the dissociation and ionization of the major species. Cooling by molecular hydrogen (rotational, vibrational and dissociation), grains and dipole molecules is included. There are three basic types of solutions (C, C asterisk, and J) and some more complicated flows involving combinations of the basic types. The initial preshock conditions cover hydrogen nuclei densities of 1 less than n less than 10(exp 10) cm(-3) and shock velocities of 5 less than v(sub s) less than 60 km/s. The magnetic field is varied over 5 decades and the sensitivity of the results to grain parameters, UV and cosmic ray fluxes is ascertained. The parameter space is quite complicated, but there exist some simple divisions. When the initial ionization fraction is small (chi sub i less than 10(-5)), there is a sharp transition between fully C solutions at low velocity and strong J solutions at high velocity. When the initial ionization fraction is larger, C asterisk and/or very weak J shocks are present at low velocities in addition to the C solutions. The flow again changes to strong J shocks at high velocities. When the ionization fraction is large and the flow is only slightly greater than the bulk Alfven velocity, there is a complicated mixture of C, C asterisk and J solutions.

  8. Measuring resilience to energy shocks

    Molyneaux, Lynette; Brown, Colin; Foster, John; Wagner, Liam

    2015-01-01

    Measuring energy security or resilience in energy is, in the main, confined to indicators which are used for comparative purposes or to show trends rather than provide empirical evidence of resilience to unpredicted crises. In this paper, the electricity systems of the individual states within the United States of America are analysed for their response to the 1973-1982 and the 2003-2012 oil price shocks. Empirical evidence is sought for elements which are present in systems that experience r...

  9. Coronal mass ejection shock fronts containing the two types of intermediate shocks

    Steinolfson, R.S.; Hundhausen, A.J.

    1990-01-01

    Numerical solutions of the time-dependent, magnetohydrodynamic (MHD) equations in two dimensions are used to demonstrate the formation of both types of intermediate shocks in a single shock front for physical conditions that are an idealization of those expected to occur in some observed coronal mass ejections. The key to producing such a shock configuration in the simulations is the use of an initial atmosphere containing a magnetic field representative of that in a coronal streamer with open field lines overlying a region of closed field lines. Previous attempts using just open field lines (perpendicular to the surface) produced shock configurations containing just one of the two intermediate shock types. A schematic of such a shock front containing both intermediate shock types has been constructed previously based solely on the known properties of MHD shocks from the Rankine-Hugoniot equations and specific requirements placed on the shock solution at points along the front where the shock normal and upstream magnetic field are aligned. The shock front also contains, at various locations along the front, a hydrodynamic (nonmagnetic) shock, a switch-on shock, and a fast shock in addition to the intermediate shocks. This particular configuration occurs when the shock front speed exceeds the upstream (preshock) intermediate wave speed but is less than a critical speed defined in the paper (equation 1) along at least some portion of the shock front. A distinctive feature of the front is that it is concave upward (away from the surface) near the region where the field in the preshock plasma is normal to the front of near the central portion of the shock front

  10. Experimental investigation of shock wave - bubble interaction

    Alizadeh, Mohsen

    2010-04-09

    In this work, the dynamics of laser-generated single cavitation bubbles exposed to lithotripter shock waves has been investigated experimentally. The energy of the impinging shock wave is varied in several steps. High-speed photography and pressure field measurements simultaneously with image acquisition provide the possibility of capturing the fast bubble dynamics under the effect of the shock wave impact. The pressure measurement is performed using a fiber optic probe hydrophone (FOPH) which operates based on optical diagnostics of the shock wave propagating medium. After a short introduction in chapter 1 an overview of the previous studies in chapter 2 is presented. The reported literatures include theoretical and experimental investigations of several configurations of physical problems in the field of bubble dynamics. In chapter 3 a theoretical description of propagation of a shock wave in a liquid like water has been discussed. Different kinds of reflection of a shock wave at an interface are taken into account. Undisturbed bubble dynamics as well as interaction between a planar shock wave and an initially spherical bubble are explored theoretically. Some physical parameters which are important in this issue such as the velocity of the shock-induced liquid jet, Kelvin impulse and kinetic energy are explained. The shock waves are generated in a water filled container by a focusing piezoelectric generator. The shock wave profile has a positive part with pulse duration of ∼1 μs followed by a longer tension tail (i.e. ∼3 μs). In chapter 4 high-speed images depict the propagation of a shock wave in the water filled tank. The maximum pressure is also derived for different intensity levels of the shock wave generator. The measurement is performed in the free field (i.e. in the absence of laser-generated single bubbles). In chapter 5 the interaction between lithotripter shock waves and laserinduced single cavitation bubbles is investigated experimentally. An

  11. Gender differences in binaural speech-evoked auditory brainstem response: are they clinically significant?

    Jalaei, Bahram; Azmi, Mohd Hafiz Afifi Mohd; Zakaria, Mohd Normani

    2018-05-17

    Binaurally evoked auditory evoked potentials have good diagnostic values when testing subjects with central auditory deficits. The literature on speech-evoked auditory brainstem response evoked by binaural stimulation is in fact limited. Gender disparities in speech-evoked auditory brainstem response results have been consistently noted but the magnitude of gender difference has not been reported. The present study aimed to compare the magnitude of gender difference in speech-evoked auditory brainstem response results between monaural and binaural stimulations. A total of 34 healthy Asian adults aged 19-30 years participated in this comparative study. Eighteen of them were females (mean age=23.6±2.3 years) and the remaining sixteen were males (mean age=22.0±2.3 years). For each subject, speech-evoked auditory brainstem response was recorded with the synthesized syllable /da/ presented monaurally and binaurally. While latencies were not affected (p>0.05), the binaural stimulation produced statistically higher speech-evoked auditory brainstem response amplitudes than the monaural stimulation (p0.80), substantive gender differences were noted in most of speech-evoked auditory brainstem response peaks for both stimulation modes. The magnitude of gender difference between the two stimulation modes revealed some distinct patterns. Based on these clinically significant results, gender-specific normative data are highly recommended when using speech-evoked auditory brainstem response for clinical and future applications. The preliminary normative data provided in the present study can serve as the reference for future studies on this test among Asian adults. Copyright © 2018 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  12. Particle Acceleration in Two Converging Shocks

    Wang, Xin; Wang, Na; Shan, Hao [Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi 830011 (China); Giacalone, Joe [Lunar and Planetary Laboratory, University of Arizona, Tucson AZ 85721 (United States); Yan, Yihua [CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Beijing 100012 (China); Ding, Mingde, E-mail: wangxin@xao.ac.cn [Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) Ministry of Education, Nanjing 210093 (China)

    2017-06-20

    Observations by spacecraft such as ACE , STEREO , and others show that there are proton spectral “breaks” with energy E {sub br} at 1–10 MeV in some large CME-driven shocks. Generally, a single shock with the diffusive acceleration mechanism would not predict the “broken” energy spectrum. The present paper focuses on two converging shocks to identify this energy spectral feature. In this case, the converging shocks comprise one forward CME-driven shock on 2006 December 13 and another backward Earth bow shock. We simulate the detailed particle acceleration processes in the region of the converging shocks using the Monte Carlo method. As a result, we not only obtain an extended energy spectrum with an energy “tail” up to a few 10 MeV higher than that in previous single shock model, but also we find an energy spectral “break” occurring on ∼5.5 MeV. The predicted energy spectral shape is consistent with observations from multiple spacecraft. The spectral “break,” then, in this case is caused by the interaction between the CME shock and Earth’s bow shock, and otherwise would not be present if Earth were not in the path of the CME.

  13. Simulation of turbulent flows containing strong shocks

    Fryxell, Bruce; Menon, Suresh

    2008-01-01

    Simulation of turbulent flows with strong shocks is a computationally challenging problem. The requirements for a method to produce accurate results for turbulence are orthogonal to those needed to treat shocks properly. In order to prevent an unphysical rate of decay of turbulent structures, it is necessary to use a method with very low numerical dissipation. Because of this, central difference schemes are widely used. However, computing strong shocks with a central difference scheme can produce unphysical post-shock oscillations that corrupt the entire flow unless additional dissipation is added. This dissipation can be difficult to localize to the area near the shock and can lead to inaccurate treatment of the turbulence. Modern high-resolution shock-capturing methods usually use upwind algorithms to provide the dissipation necessary to stabilize shocks. However, this upwind dissipation can also lead to an unphysical rate of decay of the turbulence. This paper discusses a hybrid method for simulating turbulent flows with strong shocks that couples a high-order central difference scheme with a high-resolution shock-capturing method. The shock-capturing method is used only in the vicinity of discontinuities in the flow, whereas the central difference scheme is used in the remainder of the computational domain. Results of this new method will be shown for a variety of test problems. Preliminary results for a realistic application involving detonation in gas-particle flows will also be presented.

  14. Electron velocity distributions near collisionless shocks

    Feldman, W.C.

    1984-01-01

    Recent studies of the amount of electron heating and of the shapes of electron velocity distributions across shocks near the earth are reviewed. It is found that electron heating increases with increasing shock strength but is always less than the ion heating. The scale length of electron heating is also less than that for the ions. Electron velocity distributions show characteristic shapes which depend on the strength of the shocks. At the weaker shocks, electron heating is mostly perpendicular to the ambient magnetic field, bar B, and results in Gaussian-shaped velocity distributions at low-to-moderate energies. At the stronger shocks, parallel heating predominates resulting in flat-topped velocity distributions. A reasonable interpretation of these results indicates that at the weaker shocks electron heating is dominated by a tendency toward conservation of the magnetic moment. At the stronger fast-mode shocks, this heating is thought to be dominated by an acceleration parallel to bar B produced by the macroscopic shock electric field followed by beam driven plasma instabilities. Some contribution to the heating at the stronger shocks from conservation of the magnetic moment and cross-field current-driven instabilities cannot be ruled out. Although the heating at slow-mode shocks is also dominated by instabilities driven by magnetic field-aligned electron beams, their acceleration mechanism is not yet established

  15. Comparison of sensitivity of magnetic resonance imaging and evoked potentials in the detection of brainstem involvement in multiple sclerosis

    Comi, G.; Martinelli, V.; Medaglini, S.; Locatelli, T.; Magnani, G.; Poggi, A.; Triulzi, F.

    1988-01-01

    A comparison was made of the sensitivity of magnetic resonance imaging and the combined use of Brainstem Auditory Evoked Potential and Median Somatosensory Evoked Potential in the detection of brainstem dysfunction in 54 multiple sclerosis patients. 10 refs.; 2 tabs

  16. Influence of visual angle on pattern reversal visual evoked potentials

    Ruchi Kothari

    2014-01-01

    Full Text Available Purpose: The aim of this study was to find whether the visual evoked potential (VEP latencies and amplitude are altered with different visual angles in healthy adult volunteers or not and to determine the visual angle which is the optimum and most appropriate among a wide range of check sizes for the reliable interpretation of pattern reversal VEPs (PRVEPs. Materials and Methods: The present study was conducted on 40 healthy volunteers. The subjects were divided into two groups. One group consisted of 20 individuals (nine males and 11 females in the age range of 25-57 years and they were exposed to checks subtending a visual angle of 90, 120, and 180 minutes of arc. Another group comprised of 20 individuals (10 males and 10 females in the age range of 36-60 years and they were subjected to checks subtending a visual angle of 15, 30, and 120 minutes of arc. The stimulus configuration comprised of the transient pattern reversal method in which a black and white checker board is generated (full field on a VEP Monitor by an Evoked Potential Recorder (RMS EMG. EPMARK II. The statistical analysis was done by One Way Analysis of Variance (ANOVA using EPI INFO 6. Results: In Group I, the maximum (max. P100 latency of 98.8 ± 4.7 and the max. P100 amplitude of 10.05 ± 3.1 μV was obtained with checks of 90 minutes. In Group II, the max. P100 latency of 105.19 ± 4.75 msec as well as the max. P100 amplitude of 8.23 ± 3.30 μV was obtained with 15 minutes. The min. P100 latency in both the groups was obtained with checks of 120 minutes while the min. P100 amplitude was obtained with 180 minutes. A statistically significant difference was derived between means of P100 latency for 15 and 30 minutes with reference to its value for 120 minutes and between the mean value of P100 amplitude for 120 minutes and that of 90 and 180 minutes. Conclusion: Altering the size of stimulus (visual angle has an effect on the PRVEP parameters. Our study found that the 120

  17. Computer simulations of collisionless shock waves

    Leroy, M.M.

    1984-01-01

    A review of the contributions of particle computer simulations to the understanding of the physics of magnetic shock waves in collisionless plasmas is presented. The emphasis is on the relation between the computer simulation results, spacecraft observations of shocks in space, and related theories, rather than on technical aspects of the numerics. It is shown that much has been learned from the comparison of ISEE spacecraft observations of the terrestrial bow shock and particle computer simulations concerning the quasi-perpendicular, supercritical shock (ion scale structure, ion reflection mechanism and ultimate dissipation processes). Particle computer simulations have also had an appreciable prospective role in the investigation of the physics of quasi-parallel shocks, about which still little is known observationally. Moreover, these numerical techniques have helped to clarify the process of suprathermal ion rejection by the shock into the foreshock, and the subsequent evolution of the ions in the foreshock. 95 references

  18. Molecular dynamics simulation of laser shock phenomena

    Fukumoto, Ichirou [Japan Atomic Energy Research Inst., Kansai Research Establishment, Advanced Photon Research Center, Neyagawa, Osaka (Japan).

    2001-10-01

    Recently, ultrashort-pulse lasers with high peak power have been developed, and their application to materials processing is expected as a tool of precision microfabrication. When a high power laser irradiates, a shock wave propagates into the material and dislocations are generated. In this paper, laser shock phenomena of the metal were analyzed using the modified molecular dynamics method, which has been developed by Ohmura and Fukumoto. The main results obtained are summarized as follows: (1) The shock wave induced by the Gaussian beam irradiation propagates radially from the surface to the interior. (2) A lot of dislocations are generated at the solid-liquid interface by the propagation of a shock wave. (3) Some dislocations are moved instantaneously with the velocity of the longitudinal wave when the shock wave passes, and their velocity is not larger than the transverse velocity after the shock wave has passed. (author)

  19. Entropy Generation Across Earth's Bow Shock

    Parks, George K.; McCarthy, Michael; Fu, Suiyan; Lee E. s; Cao, Jinbin; Goldstein, Melvyn L.; Canu, Patrick; Dandouras, Iannis S.; Reme, Henri; Fazakerley, Andrew; hide

    2011-01-01

    Earth's bow shock is a transition layer that causes an irreversible change in the state of plasma that is stationary in time. Theories predict entropy increases across the bow shock but entropy has never been directly measured. Cluster and Double Star plasma experiments measure 3D plasma distributions upstream and downstream of the bow shock that allow calculation of Boltzmann's entropy function H and his famous H-theorem, dH/dt O. We present the first direct measurements of entropy density changes across Earth's bow shock. We will show that this entropy generation may be part of the processes that produce the non-thermal plasma distributions is consistent with a kinetic entropy flux model derived from the collisionless Boltzmann equation, giving strong support that solar wind's total entropy across the bow shock remains unchanged. As far as we know, our results are not explained by any existing shock models and should be of interests to theorists.

  20. Remote shock sensing and notification system

    Muralidharan, Govindarajan; Britton, Charles L.; Pearce, James; Jagadish, Usha; Sikka, Vinod K.

    2008-11-11

    A low-power shock sensing system includes at least one shock sensor physically coupled to a chemical storage tank to be monitored for impacts, and an RF transmitter which is in a low-power idle state in the absence of a triggering signal. The system includes interference circuitry including or activated by the shock sensor, wherein an output of the interface circuitry is coupled to an input of the RF transmitter. The interface circuitry triggers the RF transmitting with the triggering signal to transmit an alarm message to at least one remote location when the sensor senses a shock greater than a predetermined threshold. In one embodiment the shock sensor is a shock switch which provides an open and a closed state, the open state being a low power idle state.

  1. Auditory brainstem activity and development evoked by apical versus basal cochlear implant electrode stimulation in children.

    Gordon, K A; Papsin, B C; Harrison, R V

    2007-08-01

    The role of apical versus basal cochlear implant electrode stimulation on central auditory development was examined. We hypothesized that, in children with early onset deafness, auditory development evoked by basal electrode stimulation would differ from that evoked more apically. Responses of the auditory nerve and brainstem, evoked by an apical and a basal implant electrode, were measured over the first year of cochlear implant use in 50 children with early onset severe to profound deafness who used hearing aids prior to implantation. Responses at initial stimulation were of larger amplitude and shorter latency when evoked by the apical electrode. No significant effects of residual hearing or age were found on initial response amplitudes or latencies. With implant use, responses evoked by both electrodes showed decreases in wave and interwave latencies reflecting decreased neural conduction time through the brainstem. Apical versus basal differences persisted with implant experience with one exception; eIII-eV interlatency differences decreased with implant use. Acute stimulation shows prolongation of basally versus apically evoked auditory nerve and brainstem responses in children with severe to profound deafness. Interwave latencies reflecting neural conduction along the caudal and rostral portions of the brainstem decreased over the first year of implant use. Differences in neural conduction times evoked by apical versus basal electrode stimulation persisted in the caudal but not rostral brainstem. Activity-dependent changes of the auditory brainstem occur in response to both apical and basal cochlear implant electrode stimulation.

  2. Changes of Transient Visual Evoked Potentials in Dyslexic Children

    Ka Yan Leung

    2011-05-01

    Full Text Available Objectives: To investigate the characteristics of Visual Evoked Potentials (VEP in dyslexics. Methods: Fourteen children, 7 dyslexics and 7 control, aged 7 to 8 years were recruited. All dyslexic subjects were diagnosed by clinical psychologist. All subjects are from mainstream primary schools in Hong Kong, using Chinese and Cantonese as their primary written and spoken language, having normal visual acuity and IQ. Children with reported emotional or behavioral problems or binocular vision problem were excluded. All the subjects participated in pattern-reversal VEP measurements binocularly with 1000msec recording time. Four conditions of stimulations (checkersize: 180 min of arc were applied. (15-Hz at 15% contrast (25-Hz at 1% contrast (315-Hz at 15% contrast (415-Hz at 1% contrast Results: At 15% contrast stimulus, dyslexic subjects showed smaller amplitudes in both frequencies compared with the control group, especially in higher frequency. At 1% contrast stimulus, dyslexic subjects also showed smaller amplitudes in both frequencies and obvious reduction was observed at the later part of the recording period. No observable difference was showed in the latency of both contrast conditions. Conclusion: The attenuated VEP responses in higher frequency at low contrast condition in dyslexic group showed the changes of the transient visual response and this implies an abnormality in magnocellular pathway in dyslexia.

  3. Early event related fields during visually evoked pain anticipation.

    Gopalakrishnan, Raghavan; Burgess, Richard C; Plow, Ela B; Floden, Darlene P; Machado, Andre G

    2016-03-01

    Pain experience is not only a function of somatosensory inputs. Rather, it is strongly influenced by cognitive and affective pathways. Pain anticipatory phenomena, an important limitation to rehabilitative efforts in the chronic state, are processed by associative and limbic networks, along with primary sensory cortices. Characterization of neurophysiological correlates of pain anticipation, particularly during very early stages of neural processing is critical for development of therapeutic interventions. Here, we utilized magnetoencephalography to study early event-related fields (ERFs) in healthy subjects exposed to a 3 s visual countdown task that preceded a painful stimulus, a non-painful stimulus or no stimulus. We found that the first countdown cue, but not the last cue, evoked critical ERFs signaling anticipation, attention and alertness to the noxious stimuli. Further, we found that P2 and N2 components were significantly different in response to first-cues that signaled incoming painful stimuli when compared to non-painful or no stimuli. The findings indicate that early ERFs are relevant neural substrates of pain anticipatory phenomena and could be potentially serve as biomarkers. These measures could assist in the development of neurostimulation approaches aimed at curbing the negative effects of pain anticipation during rehabilitation. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  4. Brain-stem evoked potentials and noise effects in seagulls.

    Counter, S A

    1985-01-01

    Brain-stem auditory evoked potentials (BAEP) recorded from the seagull were large-amplitude, short-latency, vertex-positive deflections which originate in the eighth nerve and several brain-stem nuclei. BAEP waveforms were similar in latency and configurations to that reported for certain other lower vertebrates and some mammals. BAEP recorded at several pure tone frequencies throughout the seagull's auditory spectrum showed an area of heightened auditory sensitivity between 1 and 3 kHz. This range was also found to be the primary bandwidth of the vocalization output of young seagulls. Masking by white noise and pure tones had remarkable effects on several parameters of the BAEP. In general, the tone- and click-induced BAEP were either reduced or obliterated by both pure tone and white noise maskers of specific signal to noise ratios and high intensity levels. The masking effects observed in this study may be related to the manner in which seagulls respond to intense environmental noise. One possible conclusion is that intense environmental noise, such as aircraft engine noise, may severely alter the seagull's localization apparatus and induce sonogenic stress, both of which could cause collisions with low-flying aircraft.

  5. Ellagic acid radiosensitizes tumor cells by evoking apoptotic pathway

    Ahire, Vidhula R.; Mishra, K.P.

    2016-01-01

    Cancer causes millions of deaths each year globally. In most patients, the cause of treatment failure is found associated with the resistance to chemotherapy and radiotherapy. The development of tumor cell resistance evokes multiple intracellular molecular pathways. In addition, the limitation in treatment outcome arises due to unintended cytotoxic effects of the synthetic anticancer drugs to normal cells and tissues. Considerable focus of research is, therefore, devoted to examine plant-based herbal compounds which may prove potential anticancer drug for developing effective cancer therapy. Research results from our laboratory have shown that ellagic acid (EA), a natural flavonoid displays enhanced tumor toxicity in combination with gamma radiation to many types of cancers in vitro as well as in vivo. Studies on the underlying mechanisms of toxicity suggest that EA employs the cellular signaling pathways in producing the observed effects. This paper gives an account of molecular mechanisms of EA-induced apoptosis process in tumor cytotoxicity. It is suggested that EA acts as a novel radiosensitizer for tumors and a radioprotector for normal cells which may offer a novel protocol for cancer treatment. (author)

  6. Pattern reversal visual evoked potentials in migraine subjects without aura

    Pedro F. Moreira Filho

    1994-12-01

    Full Text Available Twenty seven patients with migraine without aura were investigated. The age was between 12 and 54 years; 5 were men and 22 women. The diagnosis of migraine was made according to the classification proposed by the International Headache Society. The method of visual evoked potential was performed with pattern reversal (VEP-PR, with monocular stimulation. The stimulation was performed with pattern reversal with 4x4 cm black and white and red and green squared screen placed 1 meter from the nasion at stimulus frequency 1/s; 128 individual trials were analysed. The VEP-PR with black/white and red/green study showed a significant increase of value of the P-100 latency in 10 migraine patients. In 8 cases the LP100 in VEP-PR black/white was normal but in VEP-PR red/green the LP100 showed increase. Specifically in 1 of our cases, LP100 were normal in VEP-PR black/white but in the red/green there were no reproductice waves. On basis of these observations we consider that the method of VEP-PR is an useful instrument for investigation of migraine patients without aura.

  7. Mapping human brain networks with cortico-cortical evoked potentials

    Keller, Corey J.; Honey, Christopher J.; Mégevand, Pierre; Entz, Laszlo; Ulbert, Istvan; Mehta, Ashesh D.

    2014-01-01

    The cerebral cortex forms a sheet of neurons organized into a network of interconnected modules that is highly expanded in humans and presumably enables our most refined sensory and cognitive abilities. The links of this network form a fundamental aspect of its organization, and a great deal of research is focusing on understanding how information flows within and between different regions. However, an often-overlooked element of this connectivity regards a causal, hierarchical structure of regions, whereby certain nodes of the cortical network may exert greater influence over the others. While this is difficult to ascertain non-invasively, patients undergoing invasive electrode monitoring for epilepsy provide a unique window into this aspect of cortical organization. In this review, we highlight the potential for cortico-cortical evoked potential (CCEP) mapping to directly measure neuronal propagation across large-scale brain networks with spatio-temporal resolution that is superior to traditional neuroimaging methods. We first introduce effective connectivity and discuss the mechanisms underlying CCEP generation. Next, we highlight how CCEP mapping has begun to provide insight into the neural basis of non-invasive imaging signals. Finally, we present a novel approach to perturbing and measuring brain network function during cognitive processing. The direct measurement of CCEPs in response to electrical stimulation represents a potentially powerful clinical and basic science tool for probing the large-scale networks of the human cerebral cortex. PMID:25180306

  8. From acoustic descriptors to evoked quality of car door sounds.

    Bezat, Marie-Céline; Kronland-Martinet, Richard; Roussarie, Vincent; Ystad, Sølvi

    2014-07-01

    This article describes the first part of a study aiming at adapting the mechanical car door construction to the drivers' expectancies in terms of perceived quality of cars deduced from car door sounds. A perceptual cartography of car door sounds is obtained from various listening tests aiming at revealing both ecological and analytical properties linked to evoked car quality. In the first test naive listeners performed absolute evaluations of five ecological properties (i.e., solidity, quality, weight, closure energy, and success of closure). Then experts in the area of automobile doors categorized the sounds according to organic constituents (lock, joints, door panel), in particular whether or not the lock mechanism could be perceived. Further, a sensory panel of naive listeners identified sensory descriptors such as classical descriptors or onomatopoeia that characterize the sounds, hereby providing an analytic description of the sounds. Finally, acoustic descriptors were calculated after decomposition of the signal into a lock and a closure component by the Empirical Mode Decomposition (EMD) method. A statistical relationship between the acoustic descriptors and the perceptual evaluations of the car door sounds could then be obtained through linear regression analysis.

  9. Pattern Visual Evoked Potentials Elicited by Organic Electroluminescence Screen

    Celso Soiti Matsumoto

    2014-01-01

    Full Text Available Purpose. To determine whether organic electroluminescence (OLED screens can be used as visual stimulators to elicit pattern-reversal visual evoked potentials (p-VEPs. Method. Checkerboard patterns were generated on a conventional cathode-ray tube (S710, Compaq Computer Co., USA screen and on an OLED (17 inches, 320 × 230 mm, PVM-1741, Sony, Tokyo, Japan screen. The time course of the luminance changes of each monitor was measured with a photodiode. The p-VEPs elicited by these two screens were recorded from 15 eyes of 9 healthy volunteers (22.0 ± 0.8 years. Results. The OLED screen had a constant time delay from the onset of the trigger signal to the start of the luminescence change. The delay during the reversal phase from black to white for the pattern was 1.0 msec on the cathode-ray tube (CRT screen and 0.5 msec on the OLED screen. No significant differences in the amplitudes of P100 and the implicit times of N75 and P100 were observed in the p-VEPs elicited by the CRT and the OLED screens. Conclusion. The OLED screen can be used as a visual stimulator to elicit p-VEPs; however the time delay and the specific properties in the luminance change must be taken into account.

  10. Humor drawings evoked temporal and spectral EEG processes

    Kuo, Hsien-Chu; Chuang, Shang-Wen

    2017-01-01

    Abstract The study aimed to explore the humor processing elicited through the manipulation of artistic drawings. Using the Comprehension–Elaboration Theory of humor as the main research background, the experiment manipulated the head portraits of celebrities based on the independent variables of facial deformation (large/small) and addition of affective features (positive/negative). A 64-channel electroencephalography was recorded in 30 participants while viewing the incongruous drawings of celebrities. The electroencephalography temporal and spectral responses were measured during the three stages of humor which included incongruity detection, incongruity comprehension and elaboration of humor. Analysis of event-related potentials indicated that for humorous vs non-humorous drawings, facial deformation and the addition of affective features significantly affected the degree of humor elicited, specifically: large > small deformation; negative > positive affective features. The N170, N270, N400, N600-800 and N900-1200 components showed significant differences, particularly in the right prefrontal and frontal regions. Analysis of event-related spectral perturbation showed significant differences in the theta band evoked in the anterior cingulate cortex, parietal region and posterior cingulate cortex; and in the alpha and beta bands in the motor areas. These regions are involved in emotional processing, memory retrieval, and laughter and feelings of amusement induced by elaboration of the situation. PMID:28402573

  11. Brainstem auditory evoked potential testing in Dalmatian dogs in Brazil

    M.I.P. Palumbo

    2014-04-01

    Full Text Available The brain stem auditory-evoked potential (BAEP is an electrophysiologic test that detects and records the electrical activity in the auditory system from cochlea to midbrain, generated after an acoustic stimulus applied to the external ear. The aim of this study is to obtain normative data for BAEP in Dalmatian dogs in order to apply this to the evaluation of deafness and other neurologic disorders. BAEP were recorded from 30 Dalmatian dogs for a normative Brazilian study. Mean latencies for waves I, III, and V were 1.14 (±0.09, 2.62 (±0.10, and 3.46 (±0.14 ms, respectively. Mean inter-peak latencies for I-III, III-V, and I-V intervals were 1.48 (±0.17, 0.84 (±0.12, and 2.31 (±0.18 ms, respectively. Unilateral abnormalities were found in 16.7% of animals and bilateral deafness was seen in one dog. The normative data obtained in this paper is compatible with other published data. As far as we know this is the first report of deafness occurrence in Dalmatian dogs in Brazil.

  12. Development of Brainstem-Evoked Responses in Congenital Auditory Deprivation

    J. Tillein

    2012-01-01

    Full Text Available To compare the development of the auditory system in hearing and completely acoustically deprived animals, naive congenitally deaf white cats (CDCs and hearing controls (HCs were investigated at different developmental stages from birth till adulthood. The CDCs had no hearing experience before the acute experiment. In both groups of animals, responses to cochlear implant stimulation were acutely assessed. Electrically evoked auditory brainstem responses (E-ABRs were recorded with monopolar stimulation at different current levels. CDCs demonstrated extensive development of E-ABRs, from first signs of responses at postnatal (p.n. day 3 through appearance of all waves of brainstem response at day 8 p.n. to mature responses around day 90 p.n.. Wave I of E-ABRs could not be distinguished from the artifact in majority of CDCs, whereas in HCs, it was clearly separated from the stimulus artifact. Waves II, III, and IV demonstrated higher thresholds in CDCs, whereas this difference was not found for wave V. Amplitudes of wave III were significantly higher in HCs, whereas wave V amplitudes were significantly higher in CDCs. No differences in latencies were observed between the animal groups. These data demonstrate significant postnatal subcortical development in absence of hearing, and also divergent effects of deafness on early waves II–IV and wave V of the E-ABR.

  13. Vestibular-Evoked Myogenic Potentials in Bilateral Vestibulopathy

    Sally M. Rosengren

    2018-04-01

    Full Text Available Bilateral vestibulopathy (BVP is a chronic condition in which patients have a reduction or absence of vestibular function in both ears. BVP is characterized by bilateral reduction of horizontal canal responses; however, there is increasing evidence that otolith function can also be affected. Cervical and ocular vestibular-evoked myogenic potentials (cVEMPs/oVEMPs are relatively new tests of otolith function that can be used to test the saccule and utricle of both ears independently. Studies to date show that cVEMPs and oVEMPs are often small or absent in BVP but are in the normal range in a significant proportion of patients. The variability in otolith function is partly due to the heterogeneous nature of BVP but is also due to false negative and positive responses that occur because of the large range of normal VEMP amplitudes. Due to their variability, VEMPs are not part of the diagnosis of BVP; however, they are helpful complementary tests that can provide information about the extent of disease within the labyrinth. This article is a review of the use of VEMPs in BVP, summarizing the available data on VEMP abnormalities in patients and discussing the limitations of VEMPs in diagnosing bilateral loss of otolith function.

  14. Optimization of visual evoked potential (VEP) recording systems.

    Karanjia, Rustum; Brunet, Donald G; ten Hove, Martin W

    2009-01-01

    To explore the influence of environmental conditions on pattern visual evoked potential (VEP) recordings. Fourteen subjects with no known ocular pathology were recruited for the study. In an attempt to optimize the recording conditions, VEP recordings were performed in both the seated and recumbent positions. Comparisons were made between recordings using either LCD or CRT displays and recordings obtained in silence or with quiet background music. Paired recordings (in which only one variable was changed) were analyzed for changes in P100 latency, RMS noise, and variability. Baseline RMS noise demonstrated a significant decrease in the variability during the first 50msec accompanied by a 73% decrease in recording time for recumbent position when compared to the seated position (pmusic did not affect the amount of RMS noise during the first 50msec of the recordings. This study demonstrates that the use of the recumbent position increases patient comfort and improves the signal to noise ratio. In contrast, the addition of background music to relax the patient did not improve the recording signal. Furthermore, the study illustrates the importance of avoiding low-contrast visual stimulation patterns obtained with LCD as they lead to higher latencies resulting in false positive recordings. These findings are important when establishing or modifying a pattern VEP recording protocol.

  15. Effect of practicing yoga on cervical vestibular evoked myogenic potential.

    Shambhu, Tejaswini; Kumar, Shubhaganga Dhrruva; Prabhu, Prashanth

    2017-10-01

    The present study attempted to determine the effect of practicing yoga on functioning of sacculo-collic pathway using cervical vestibular evoked myogenic potential (cVEMP). cVEMP was recorded from 40 participants (20 who practice yoga regularly and 20 who do not practice yoga regularly). The differences in amplitude of P1, N1, P1-N1 complex, asymmetry ratio and latencies of P1 and N1 of cVEMP were compared between both the groups. The results of the study showed that there was a significant increase (p yoga was significantly lower (Mean = 6.73) compared to the control group (Mean = 19.13). Multivariate regression analyses suggested that the number of years of yoga practice significantly predicted the amplitude of P1-N1 complex (β = 0.70, p yoga improves postural control and strengthens the muscles and vestibular system leading to enhanced cVEMP responses. The plastic changes in the vestibular system and increased muscular strength because of constant practicing of yoga could have led to changes in cVEMP responses. However, further studies on a larger group of individuals are essential for better clinical applicability of the results.

  16. Humor drawings evoked temporal and spectral EEG processes.

    Wang, Regina W Y; Kuo, Hsien-Chu; Chuang, Shang-Wen

    2017-08-01

    The study aimed to explore the humor processing elicited through the manipulation of artistic drawings. Using the Comprehension-Elaboration Theory of humor as the main research background, the experiment manipulated the head portraits of celebrities based on the independent variables of facial deformation (large/small) and addition of affective features (positive/negative). A 64-channel electroencephalography was recorded in 30 participants while viewing the incongruous drawings of celebrities. The electroencephalography temporal and spectral responses were measured during the three stages of humor which included incongruity detection, incongruity comprehension and elaboration of humor. Analysis of event-related potentials indicated that for humorous vs non-humorous drawings, facial deformation and the addition of affective features significantly affected the degree of humor elicited, specifically: large > small deformation; negative > positive affective features. The N170, N270, N400, N600-800 and N900-1200 components showed significant differences, particularly in the right prefrontal and frontal regions. Analysis of event-related spectral perturbation showed significant differences in the theta band evoked in the anterior cingulate cortex, parietal region and posterior cingulate cortex; and in the alpha and beta bands in the motor areas. These regions are involved in emotional processing, memory retrieval, and laughter and feelings of amusement induced by elaboration of the situation. © The Author (2017). Published by Oxford University Press.

  17. Pattern visual evoked potentials elicited by organic electroluminescence screen.

    Matsumoto, Celso Soiti; Shinoda, Kei; Matsumoto, Harue; Funada, Hideaki; Sasaki, Kakeru; Minoda, Haruka; Iwata, Takeshi; Mizota, Atsushi

    2014-01-01

    To determine whether organic electroluminescence (OLED) screens can be used as visual stimulators to elicit pattern-reversal visual evoked potentials (p-VEPs). Checkerboard patterns were generated on a conventional cathode-ray tube (S710, Compaq Computer Co., USA) screen and on an OLED (17 inches, 320 × 230 mm, PVM-1741, Sony, Tokyo, Japan) screen. The time course of the luminance changes of each monitor was measured with a photodiode. The p-VEPs elicited by these two screens were recorded from 15 eyes of 9 healthy volunteers (22.0 ± 0.8 years). The OLED screen had a constant time delay from the onset of the trigger signal to the start of the luminescence change. The delay during the reversal phase from black to white for the pattern was 1.0 msec on the cathode-ray tube (CRT) screen and 0.5 msec on the OLED screen. No significant differences in the amplitudes of P100 and the implicit times of N75 and P100 were observed in the p-VEPs elicited by the CRT and the OLED screens. The OLED screen can be used as a visual stimulator to elicit p-VEPs; however the time delay and the specific properties in the luminance change must be taken into account.

  18. Effect of word familiarity on visually evoked magnetic fields.

    Harada, N; Iwaki, S; Nakagawa, S; Yamaguchi, M; Tonoike, M

    2004-11-30

    This study investigated the effect of word familiarity of visual stimuli on the word recognizing function of the human brain. Word familiarity is an index of the relative ease of word perception, and is characterized by facilitation and accuracy on word recognition. We studied the effect of word familiarity, using "Hiragana" (phonetic characters in Japanese orthography) characters as visual stimuli, on the elicitation of visually evoked magnetic fields with a word-naming task. The words were selected from a database of lexical properties of Japanese. The four "Hiragana" characters used were grouped and presented in 4 classes of degree of familiarity. The three components were observed in averaged waveforms of the root mean square (RMS) value on latencies at about 100 ms, 150 ms and 220 ms. The RMS value of the 220 ms component showed a significant positive correlation (F=(3/36); 5.501; p=0.035) with the value of familiarity. ECDs of the 220 ms component were observed in the intraparietal sulcus (IPS). Increments in the RMS value of the 220 ms component, which might reflect ideographical word recognition, retrieving "as a whole" were enhanced with increments of the value of familiarity. The interaction of characters, which increased with the value of familiarity, might function "as a large symbol"; and enhance a "pop-out" function with an escaping character inhibiting other characters and enhancing the segmentation of the character (as a figure) from the ground.

  19. Changes in vestibular evoked myogenic potentials after Meniere attacks.

    Kuo, Shih-Wei; Yang, Ting-Hua; Young, Yi-Ho

    2005-09-01

    The aim of this study was to apply videonystagmography (VNG) and vestibular evoked myogenic potential (VEMP) tests to patients with Meniere attacks, to explore the mechanics of where saccular disorders may affect the semicircular canals. From January 2001 to December 2003, 12 consecutive patients with unilateral definite Meniere's disease with vertiginous attacks underwent VNG for recording spontaneous nystagmus, as well as VEMP tests. At the very beginning of the Meniere attack, the spontaneous nystagmus beat toward the lesion side in 5 patients (42%) and toward the healthy side in 7 patients (58%). Twenty-four hours later, only 6 patients (50%) showed spontaneous nystagmus beating toward the healthy side. Nevertheless, spontaneous nystagmus subsided in all patients within 48 hours. The VEMP test was performed within 24 hours of a Meniere attack; the VEMPs were normal in 4 patients and abnormal in 8 patients (67%). After 48 hours, 4 patients with initially abnormal VEMPs had resolution and return to normal VEMPs, and the other 4 patients still had absent VEMPs. Most patients (67%) with Meniere attacks revealed abnormal VEMPs, indicating that the saccule participates in a Meniere attack. This is an important idea that stimulates consideration of the mechanism of Meniere attacks.

  20. Pyrethroid insecticides evoke neurotransmitter release from rabbit striatal slices

    Eells, J.T.; Dubocovich, M.L.

    1988-01-01

    The effects of the synthetic pyrethroid insecticide fenvalerate ([R,S]-alpha-cyano-3-phenoxybenzyl[R,S]-2-(4-chlorophenyl)-3- methylbutyrate) on neurotransmitter release in rabbit brain slices were investigated. Fenvalerate evoked a calcium-dependent release of [ 3 H]dopamine and [ 3 H]acetylcholine from rabbit striatal slices that was concentration-dependent and specific for the toxic stereoisomer of the insecticide. The release of [ 3 H]dopamine and [ 3 H]acetylcholine by fenvalerate was modulated by D2 dopamine receptor activation and antagonized completely by the sodium channel blocker, tetrodotoxin. These findings are consistent with an action of fenvalerate on the voltage-dependent sodium channels of the presynaptic membrane resulting in membrane depolarization, and the release of dopamine and acetylcholine by a calcium-dependent exocytotic process. In contrast to results obtained in striatal slices, fenvalerate did not elicit the release of [ 3 H]norepinephrine or [ 3 H]acetylcholine from rabbit hippocampal slices indicative of regional differences in sensitivity to type II pyrethroid actions

  1. Role of echocardiography in reducing shock reversal time in pediatric septic shock: a randomized controlled trial

    Ahmed A. EL‐Nawawy

    2018-01-01

    Conclusion: Serial echocardiography provided crucial data for early recognition of septic myocardial dysfunction and hypovolemia that was not apparent on clinical assessment, allowing a timely management and resulting in shock reversal time reduction among children with septic shock.

  2. The earth's foreshock, bow shock, and magnetosheath

    Onsager, T. G.; Thomsen, M. F.

    1991-01-01

    Studies directly pertaining to the earth's foreshock, bow shock, and magnetosheath are reviewed, and some comparisons are made with data on other planets. Topics considered in detail include the electron foreshock, the ion foreshock, the quasi-parallel shock, the quasi-perpendicular shock, and the magnetosheath. Information discussed spans a broad range of disciplines, from large-scale macroscopic plasma phenomena to small-scale microphysical interactions.

  3. The earth's foreshock, bow shock, and magnetosheath

    Onsager, T.G.; Thomsen, M.F.

    1991-01-01

    Studies directly pertaining to the earth's foreshock, bow shock, and magnetosheath are reviewed, and some comparisons are made with data on other planets. Topics considered in detail include the electron foreshock, the ion foreshock, the quasi-parallel shock, the quasi-perpendicular shock, and the magnetosheath. Information discussed spans a broad range of disciplines, from large-scale macroscopic plasma phenomena to small-scale microphysical interactions. 184 refs

  4. Nonequilibrium chemistry in shocked molecular clouds

    Iglesias, E.R.; Silk, J.

    1978-01-01

    The gas phase chemistry is studied behind a 10 km s -1 shock propagating into a dense molecular cloud. Our principal conclusions are that the concentrations of certain molecules (CO, NH 3 , HCN, N 2 ) are unperturbed by the shock; other molecules (H 2 CO, CN, HCO + ) are greatly decreased in abundance; and substantial amounts of H 2 O, HCO, and CH 4 are produced. Approximately 10 6 yr (independent of the density) must elapse after shock passage before chemical equilibrium is attained

  5. Reaction effects in diffusive shock acceleration

    Drury, L.Oc.

    1984-01-01

    The effects of the reaction of accelerated particles back on the shock wave in the diffusive-shock-acceleration model of cosmic-ray generation are investigated theoretically. Effects examined include changes in the shock structure, modifications of the input and output spectra, scattering effects, and possible instabilities in the small-scale structure. It is pointed out that the latter two effects are applicable to any spatially localized acceleration mechanism. 14 references

  6. PIV tracer behavior on propagating shock fronts

    Glazyrin, Fyodor N; Mursenkova, Irina V; Znamenskaya, Irina A

    2016-01-01

    The present work was aimed at the quantitative particle image velocimetry (PIV) measurement of a velocity field near the front of a propagating shock wave and the study of the dynamics of liquid tracers crossing the shock front. For this goal, a shock tube with a rectangular cross-section (48  ×  24 mm) was used. The flat shock wave with Mach numbers M  =  1.4–2.0 propagating inside the tube channel was studied as well as an expanding shock wave propagating outside the channel with M  =  1.2–1.8 at its main axis. The PIV imaging of the shock fronts was carried out with an aerosol of dioctyl sebacate (DEHS) as tracer particles. The pressures of the gas in front of the shock waves studied ranged from 0.013 Mpa to 0.1 MPa in the series of experiments. The processed PIV data, compared to the 1D normal shock theory, yielded consistent values of wake velocity immediately behind the plain shock wave. Special attention was paid to the blurring of the velocity jump on the shock front due to the inertial particle lag and peculiarities of the PIV technique. A numerical algorithm was developed for analysis and correction of the PIV data on the shock fronts, based on equations of particle-flow interaction. By application of this algorithm, the effective particle diameter of the DEHS aerosol tracers was estimated as 1.03  ±  0.12 μm. A number of different formulations for particle drag were tested with this algorithm, with varying success. The results show consistency with previously reported experimental data obtained for cases of stationary shock waves. (paper)

  7. Condensed matter at high shock pressures

    Nellis, W.J.; Holmes, N.C.; Mitchell, A.C.; Radousky, H.B.; Hamilton, D.

    1985-01-01

    Experimental techniques are described for shock waves in liquids: Hugoniot equation-of-state, shock temperature and emission spectroscopy, electrical conductivity, and Raman spectroscopy. Experimental data are reviewed and presented in terms of phenomena that occur at high densities and temperatures in shocked He, Ar, N 2 , CO, SiO 2 -aerogel, H 2 O, and C 6 H 6 . The superconducting properties of Nb metal shocked to 100 GPa (1 Mbar) and recovered intact are discussed in terms of prospects for synthesizing novel, metastable materials. Ultrahigh pressure data for Cu is reviewed in the range 0.3 to 6TPa (3 to 60 Mbar). 56 refs., 9 figs., 1 tab

  8. Radio emission from coronal and interplanetary shocks

    Cane, H.V.

    1987-01-01

    Observational data on coronal and interplanetary (IP) type II burst events associated with shock-wave propagation are reviewed, with a focus on the past and potential future contributions of space-based observatories. The evidence presented by Cane (1983 and 1984) in support of the hypothesis that the coronal (metric) and IP (kilometric) bursts are due to different shocks is summarized, and the fast-drift kilometric events seen at the same time as metric type II bursts (and designated shock-accelerated or shock-associated events) are characterized. The need for further observations at 0.5-20 MHz is indicated. 20 references

  9. Advanced and Exploratory Shock Sensing Mechanisms.

    Nelsen, Nicholas H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kolb, James D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kulkarni, Akshay G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sorscher, Zachary [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Habing, Clayton D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mathis, Allen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Beller, Zachary J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    Mechanical component response to shock environments must be predictable in order to ensure reliability and safety. Whether the shock input results from accidental drops during transportation to projectile impact scenarios, the system must irreversibly transition into a safe state that is incapable of triggering the component . With this critical need in mind, the 2017 Nuclear Weapons Summer Product Realization Institute (NW SPRINT) program objective sought the design of a passive shock failsafe with emphasis on additively manufactured (AM) components. Team Advanced and Exploratory (A&E) responded to the challenge by designing and delivering multiple passive shock sensing mech anisms that activate within a prescribed mechanical shock threshold. These AM failsafe designs were tuned and validated using analytical and computational techniques including the shock response spectrum (SRS) and finite element analysis (FEA). After rapid prototyping, the devices experienced physical shock tests conducted on Sandia drop tables to experimentally verify performance. Keywords: Additive manufacturing, dynamic system, failsafe, finite element analysis, mechanical shock, NW SPRINT, shock respon se spectrum

  10. Irreversible thermodynamics of overdriven shocks in solids

    Wallace, D.C.

    1981-01-01

    An isotropic solid capable of transporting heat and of undergoing dissipative plastic flow, is treated. The shock is assumed to be a steady wave, and any phase changes or macroscopic inhomogeneities which might be induced by the shock are neglected. Under these conditions it is established that for an overdriven shock, no solution is possible without heat transport, and when the heat transport is governed by the steady conduction equation, no solution is possible without plastic dissipation as well. Upper and lower bounds are established for the thermodynamic variables, namely the shear stress, temperature, entropy, plastic strain, and heat flux, as functions of compression through the shock

  11. The Universal Role of Tubulence in the Propagation of Strong Shocks and Detonation Waves

    Lee, John H.

    2001-06-01

    direction of propagation) apply across the shock transition zone if the downstream equilibrium plane is taken far enough away to ensure the decay of the turbulent fluctuations. Thus, the Hugoniot properties of one-dimensional propagation of shock and detonation waves remain valid. However, the conservation laws do not describe the important propagation mechanisms (i.e., the physical and chemical processes that effect the transition from initial to the final state) in the wave structure. Since gaseous detonations enjoy the advantage of being able to be observed experimentally in great detail, its complex turbulent structure is now quite well established. Furthermore, the equation of state for perfect gases is well known and the chemistry of most gas phase reactions is also sufficiently understood quantitatively to permit detailed numerical simulation of the complex detonation structure. Thus, a good database of information exists for gaseous detonation, and in this paper we shall explore the turbulent structure of gaseous detonation with the aim of answering the question as to "why nature prefers to evoke such a complicated manner to effect its propagation." We will then attempt to generalize the discussion to the "terra incognita" of condensed phase materials where the structure is much less understood. 1. Meshcheryakov, Yu.I., and Atroshenko, S.A., Izv. Vyssh. Uchebn. Zaved. Fiz., 4, 105-123 (1992). 2. Glass, I.I, and Liu, W.S., J. Fluid Mech., 84(1), 55-77 (1978). 3. Griffiths, R.W., Sanderman, R.J., and Hornung, H.G., J. Phys. D., 8, 1681-1691 (1975). 4. Lee, J.H.S., Ann. Rev. Fluid Mech., 16, 311-336 (1984). 5. Mallory, H.D., J. Appl. Physics, 38, 5302-5306 (1967).

  12. The source of real and nominal exchange rate fluctuations in Thailand: Real shock or nominal shock

    Le Thanh, Binh

    2015-01-01

    This paper examines the source of exchange rate fluctuations in Thailand. We employed a structural vector auto-regression (SVAR) model with the long-run neutrality restriction of Blanchard and Quah (1989) to investigate the changes in real and nominal exchange rates from 1994 to 2015. In this paper, we assume that there are two types of shocks which related to exchange rate movements: real shocks and nominal shocks. The empirical analysis indicates that real shocks are the fundamental compon...

  13. Visual cortical somatosensory and brainstem auditory evoked potentials following incidental irradiation of the rhombencephalon

    Nightingale, S.; Schofield, I.S.; Dawes, P.J.D.K.

    1984-01-01

    Visual, cortical somatosensory and brainstem auditory evoked potentials were recorded before incidental irradiation of the rhombencephalon during radiotherapy in and around the middle ear, and at 11 weeks and eight months after completion of treatment. No patient experienced neurological symptoms during this period. No consistent changes in evoked potentials were found. The failure to demonstrate subclinical radiation-induced demyelination suggests either that the syndrome of early-delayed radiation rhombencephalopathy occurs in an idiosyncratic manner, or that any subclinical lesions are not detectable by serial evoked potential recordings. (author)

  14. Music-evoked emotions: principles, brain correlates, and implications for therapy.

    Koelsch, Stefan

    2015-03-01

    This paper describes principles underlying the evocation of emotion with music: evaluation, resonance, memory, expectancy/tension, imagination, understanding, and social functions. Each of these principles includes several subprinciples, and the framework on music-evoked emotions emerging from these principles and subprinciples is supposed to provide a starting point for a systematic, coherent, and comprehensive theory on music-evoked emotions that considers both reception and production of music, as well as the relevance of emotion-evoking principles for music therapy. © 2015 New York Academy of Sciences.

  15. Visual cortical somatosensory and brainstem auditory evoked potentials following incidental irradiation of the rhombencephalon

    Nightingale, S. (Royal Victoria Infirmary, Newcastle upon Tyne (UK)); Schofield, I.S.; Dawes, P.J.D.K. (Newcastle upon Tyne Univ. (UK). Newcastle General Hospital)

    1984-01-01

    Visual, cortical somatosensory and brainstem auditory evoked potentials were recorded before incidental irradiation of the rhombencephalon during radiotherapy in and around the middle ear, and at 11 weeks and eight months after completion of treatment. No patient experienced neurological symptoms during this period. No consistent changes in evoked potentials were found. The failure to demonstrate subclinical radiation-induced demyelination suggests either that the syndrome of early-delayed radiation rhombencephalopathy occurs in an idiosyncratic manner, or that any subclinical lesions are not detectable by serial evoked potential recordings.

  16. Model for shock wave chaos.

    Kasimov, Aslan R; Faria, Luiz M; Rosales, Rodolfo R

    2013-03-08

    We propose the following model equation, u(t) + 1/2(u(2)-uu(s))x = f(x,u(s)) that predicts chaotic shock waves, similar to those in detonations in chemically reacting mixtures. The equation is given on the half line, xorder partial differential equation. The chaos arises in the equation thanks to an interplay between the nonlinearity of the inviscid Burgers equation and a novel forcing term that is nonlocal in nature and has deep physical roots in reactive Euler equations.

  17. Adaptive inertial shock-absorber

    Faraj, Rami; Holnicki-Szulc, Jan; Knap, Lech; Seńko, Jarosław

    2016-01-01

    This paper introduces and discusses a new concept of impact absorption by means of impact energy management and storage in dedicated rotating inertial discs. The effectiveness of the concept is demonstrated in a selected case-study involving spinning management, a recently developed novel impact-absorber. A specific control technique performed on this device is demonstrated to be the main source of significant improvement in the overall efficiency of impact damping process. The influence of various parameters on the performance of the shock-absorber is investigated. Design and manufacturing challenges and directions of further research are formulated. (paper)

  18. Converging shocks in elastic-plastic solids.

    Ortega, A López; Lombardini, M; Hill, D J

    2011-11-01

    We present an approximate description of the behavior of an elastic-plastic material processed by a cylindrically or spherically symmetric converging shock, following Whitham's shock dynamics theory. Originally applied with success to various gas dynamics problems, this theory is presently derived for solid media, in both elastic and plastic regimes. The exact solutions of the shock dynamics equations obtained reproduce well the results obtained by high-resolution numerical simulations. The examined constitutive laws share a compressible neo-Hookean structure for the internal energy e=e(s)(I(1))+e(h)(ρ,ς), where e(s) accounts for shear through the first invariant of the Cauchy-Green tensor, and e(h) represents the hydrostatic contribution as a function of the density ρ and entropy ς. In the strong-shock limit, reached as the shock approaches the axis or origin r=0, we show that compression effects are dominant over shear deformations. For an isothermal constitutive law, i.e., e(h)=e(h)(ρ), with a power-law dependence e(h) is proportional to ρ(α), shock dynamics predicts that for a converging shock located at r=R(t) at time t, the Mach number increases as M is proportional to [log(1/R)](α), independently of the space index s, where s=2 in cylindrical geometry and 3 in spherical geometry. An alternative isothermal constitutive law with p(ρ) of the arctanh type, which enforces a finite density in the strong-shock limit, leads to M is proportional to R(-(s-1)) for strong shocks. A nonisothermal constitutive law, whose hydrostatic part e(h) is that of an ideal gas, is also tested, recovering the strong-shock limit M is proportional to R(-(s-1)/n(γ)) originally derived by Whitham for perfect gases, where γ is inherently related to the maximum compression ratio that the material can reach, (γ+1)/(γ-1). From these strong-shock limits, we also estimate analytically the density, radial velocity, pressure, and sound speed immediately behind the shock. While the

  19. Shock compression profiles in ceramics

    Grady, D.E.; Moody, R.L.

    1996-03-01

    An investigation of the shock compression properties of high-strength ceramics has been performed using controlled planar impact techniques. In a typical experimental configuration, a ceramic target disc is held stationary, and it is struck by plates of either a similar ceramic or by plates of a well-characterized metal. All tests were performed using either a single-stage propellant gun or a two-stage light-gas gun. Particle velocity histories were measured with laser velocity interferometry (VISAR) at the interface between the back of the target ceramic and a calibrated VISAR window material. Peak impact stresses achieved in these experiments range from about 3 to 70 GPa. Ceramics tested under shock impact loading include: Al{sub 2}O{sub 3}, AlN, B{sub 4}C, SiC, Si{sub 3}N{sub 4}, TiB{sub 2}, WC and ZrO{sub 2}. This report compiles the VISAR wave profiles and experimental impact parameters within a database-useful for response model development, computational model validation studies, and independent assessment of the physics of dynamic deformation on high-strength, brittle solids.

  20. Shock-resistant scintillation detector

    Novak, W.P.

    1979-01-01

    A unique scintillation detector unit is disclosed which employs a special light transfer and reflector means that encases and protects the scintillator crystal against high g forces. The light transfer means comprises a flexible silicon rubber optical material bonded between the crystal and the optical window and having an axial thickness sufficient to allow the scintillator to move axially inside the container under high g forces without destroying the bonds. The reflector means comprises a soft elastic silicone rubber sleeve having a multiplicity of closely arranged tapered protrusions radiating toward and engaging the periphery of the scintillator crystal to cushion shocks effectively and having a reflective material, such as aluminum oxide powder, in the spaces between the protrusions. The reflector means provides improved shock absorption because of the uniform support and cushioning action of the protrusions and also provides the detector with high efficiency. The silicon rubber composition is specially compounded to include a large amount of aluminum oxide which enables the rubber to function effectively as a light reflector

  1. Brainstem auditory-evoked potential in Boxer dogs

    Mariana Isa Poci Palumbo

    2014-10-01

    Full Text Available Brainstem auditory-evoked potential (BAEP has been widely used for different purposes in veterinary practice and is commonly used to identify inherited deafness and presbycusis. In this study, 43 Boxer dogs were evaluated using the BAEP. Deafness was diagnosed in 3 dogs (2 bilateral and 1 unilateral allowing the remaining 40 Boxers to be included for normative data analysis including an evaluation on the influence of age on the BAEP. The animals were divided into 2 groups of 20 Boxers each based on age. The mean age was 4.54 years (range, 1-8 in group I, and 9.83 years (range, 8.5-12 in group II. The mean latency for I, III, and V waves were 1.14 (±0.07, 2.64 (±0.11, and 3.48 (±0.10 ms in group I, and 1.20 (±0.12, 2.73 (±0.15, and 3.58 (±0.22 ms in group II, respectively. The mean inter-peak latencies for the I-III, III-V and I-V intervals were 1.50 (±0.15, 0.84 (±0.15, and 2.34 (±0.11 ms in group I, and 1.53 (±0.16, 0.85 (±0.15, and 2.38 (±0.19 ms in group II, respectively. Latencies of waves I and III were significant different between group I and II. For the I-III, III-V and I-V intervals, no significant differences were observed between the 2 groups. As far as we know, this is the first normative study of BAEP obtained from Boxer dogs.

  2. Collaborative Learning in Higher Education: Evoking Positive Interdependence.

    Scager, Karin; Boonstra, Johannes; Peeters, Ton; Vulperhorst, Jonne; Wiegant, Fred

    Collaborative learning is a widely used instructional method, but the learning potential of this instructional method is often underused in practice. Therefore, the importance of various factors underlying effective collaborative learning should be determined. In the current study, five different life sciences undergraduate courses with successful collaborative-learning results were selected. This study focuses on factors that increased the effectiveness of collaboration in these courses, according to the students. Nine focus group interviews were conducted and analyzed. Results show that factors evoking effective collaboration were student autonomy and self-regulatory behavior, combined with a challenging, open, and complex group task that required the students to create something new and original. The design factors of these courses fostered a sense of responsibility and of shared ownership of both the collaborative process and the end product of the group assignment. In addition, students reported the absence of any free riders in these group assignments. Interestingly, it was observed that students seemed to value their sense of achievement, their learning processes, and the products they were working on more than their grades. It is concluded that collaborative learning in higher education should be designed using challenging and relevant tasks that build shared ownership with students. © 2016 K. Scager et al. CBE—Life Sciences Education © 2016 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  3. Visual Evoked Potential to Assess Retinopathy in Gestational Diabetes Mellitus.

    Hari Kumar, K V S; Ahmad, F M H; Sood, Sandeep; Mansingh, Sudhir

    2016-04-01

    We evaluated for early retinopathy using the visual evoked potential (VEP) in patients with gestational diabetes mellitus (GDM) and type 2 diabetes mellitus during pregnancy. All patients with GDM and type 2 diabetes seen between June and October of 2014 were included in this cross-sectional, observational study. Patients with secondary diabetes, ocular or major illness were excluded from the study. VEP was recorded in both eyes to derive prominent positive peak latency (P100), amplitude and initial negative deflection (N75) latency. The data were compared with 10 gestational age-matched controls with normal glucose tolerance. Appropriate statistical methods were used for comparison among the 3 groups. The study participants (40 with GDM, 10 with type 2 diabetes, 10 with normal glucose tolerance) had a median (25th to 75th interquartile range) age of 26 (24.3, 30) years, a gestational age of 24.5 (21, 27) weeks and weights of 66.8 (63.4, 71.5) kg. The P100 latencies were comparable among the 3 groups (p=0.0577). However, patients with any diabetes (GDM and type 2 diabetes) had prolonged P100 latencies (p=0.0139) and low P100 amplitudes (p=0.0391) in comparison to controls. P100 latency showed a direct correlation with hyperglycemia (p=0.0118). Our data showed that VEP abnormalities are detectable even in the short-term hyperglycemia of GDM and type 2 diabetes. Copyright © 2016 Canadian Diabetes Association. Published by Elsevier Inc. All rights reserved.

  4. Neural correlates of heat-evoked pain memory in humans.

    Wang, Liping; Gui, Peng; Li, Lei; Ku, Yixuan; Bodner, Mark; Fan, Gaojie; Zhou, Yong-Di; Dong, Xiao-Wei

    2016-03-01

    The neural processes underlying pain memory are not well understood. To explore these processes, contact heat-evoked potentials (CHEPs) were recorded in humans with electroencephalography (EEG) technique during a delayed matching-to-sample task, a working memory task involving presentations of two successive painful heat stimuli (S-1 and S-2) with different intensities separated by a 2-s interval (the memorization period). At the end of the task, the subject was required to discriminate the stimuli by indicating which (S-1 or S-2) induced more pain. A control task was used, in which no active discrimination was required between stimuli. All event-related potential (ERP) analysis was aligned to the onset of S-1. EEG activity exhibited two successive CHEPs: an N2-P2 complex (∼400 ms after onset of S-1) and an ultralate component (ULC, ∼900 ms). The amplitude of the N2-P2 at vertex, but not the ULC, was significantly correlated with stimulus intensity in these two tasks, suggesting that the N2-P2 represents neural coding of pain intensity. A late negative component (LNC) in the frontal recording region was observed only in the memory task during a 500-ms period before onset of S-2. LNC amplitude differed between stimulus intensities and exhibited significant correlations with the N2-P2 complex. These indicate that the frontal LNC is involved in maintenance of intensity of pain in working memory. Furthermore, alpha-band oscillations observed in parietal recording regions during the late delay displayed significant power differences between tasks. This study provides in the temporal domain previously unidentified neural evidence showing the neural processes involved in working memory of painful stimuli. Copyright © 2016 the American Physiological Society.

  5. Sensory disturbance, CT, and somatosensory evoked potentials in thalamic hemorrhages

    Koga, Hisanobu; Miyazaki, Takayoshi; Miyazaki, Hisaya

    1985-01-01

    Thalamic hemorrhages often lead to sensory disturbances. However, no effective method for the evaluation of their prognoses has yet been clinically utilized. The somatosensory evoked potential (SEP) has been reported as an effective method, but it remains controversial. A CT scan is eminently suitable for determining the size and position of the hemorrhage. However, the correlation between the localization of the hematoma on the CT scan and the sensory distrubance has not been investigated fully. The authors selected 20 cases with the chronic stage of a thalamic hemorrhage. Each one was clinically evaluated as to sensory disturbance; they were then classified into the following five groups: Group 1: no sensory deficit (3 cases); Group 2: complete recovery from initial deficit (2 cases); Group 3: mild hypesthesia (5 cases); Group 4: severe hypesthesia (5 cases), and Group 5: paresthesia or dysesthesia (5 cases). Also, the CT scan was investigated with regard to the localization of the hematoma and the SEP. We could thus find a characteristic pattern in each group. The results may be summarized as follows. 1. The correlation between the degree of the sensory disturbance and the size and expansion of the hematoma was clearly detected. Especially, the most severe sensory disturbance was found in the hematoma extending to the lateral nuclear and ventral nuclear regions. 2. In Group 1 and 2, each SEP component (N 1 N 2 N 3 ) was shown to be normal. In Group 3, SEP components could be detected, but not completely. In Group 4, no components at all could be found. 3. In Group 5, all cases were small hematoma localized in the lateral nuclear region of the thalamus, while the N 3 components were prolonged on the SEP findings. The authors demonstrate the results and discuss the correlation between the sensory disturbance and the CT or SEP findings. (author)

  6. Paying attention to orthography: A visual evoked potential study

    Anthony Thomas Herdman

    2013-05-01

    Full Text Available In adult readers, letters and words are rapidly identified within visual networks to allow for efficient reading abilities. Neuroimaging studies of orthography have mostly used words and letter strings that recruit many hierarchical levels in reading. Understanding how single letters are processed could provide further insight into orthographic processing. The present study investigated orthographic processing using single letters and pseudoletters when adults were encouraged to pay attention to or away from orthographic features. We measured evoked potentials (EPs to single letters and pseudoletters from adults while they performed an orthographic-discrimination task (letters vs. pseudoletters, a colour-discrimination task (red vs. blue, and a target-detection task (respond to #1 and #2. Larger and later peaking N1 responses (~170ms and larger P2 responses (~250 ms occurred to pseudoletters as compared to letters. This reflected greater visual processing for pseudoletters. Dipole analyses localized this effect to bilateral fusiform and inferior temporal cortices. Moreover, this letter-pseudoletter difference was not modulated by task and thus indicates that directing attention to or away from orthographic features didn’t affect early visual processing of single letters or pseudoletters within extrastriate regions. Paying attention to orthography or colour as compared to disregarding the stimuli (target-detection task elicited selection negativities at about 175 ms, which were followed by a classical N2-P3 complexes. This indicated that the tasks sufficiently drew participant’s attention to and away from the stimuli. Together these findings revealed that visual processing of single letters and pseudoletters, in adults, appeared to be sensory-contingent and independent of paying attention to stimulus features (e.g., orthography or colour.

  7. Conditioning stimulation techniques for enhancement of transcranially elicited evoked motor responses

    Journee, H. -L.; Polak, H. E.; De Kleuver, M.

    2007-01-01

    Introduction. - In spite of the use of multipulse, transcranial electrical stimulation (TES) is still insufficient in a subgroup of patients to elicit motor-evoked potentials during intraoperative neurophysiological monitoring (IONM). Classic facilitation methods used in awake patients are precluded

  8. An inventory and update of jealousy-evoking partner behaviours in modern society.

    Dijkstra, Pieternel; Barelds, Dick P H; Groothof, Hinke A K

    2010-01-01

    The goal of the present study was to identify the most important jealousy-evoking partner behaviours and to examine the extent to which these behaviours evoke jealousy. Based on the literature, a questionnaire was constructed containing 42 jealousy-evoking partner behaviours, including a partner's extra-dyadic involvement with someone else by means of modern communication devices, such as the Internet. A second study examined the extent to which undergraduates and a community sample experienced jealousy in response to these partner behaviours. Results showed that explicit unfaithful behaviours evoked most feelings of jealousy, followed by a partner's emotional or romantic involvement with someone else by means of modern communication devices. In general, older individuals responded with less jealousy in response to a partner's unfaithful and suspicious behaviours. Clinical implications are discussed. (c) 2009 John Wiley & Sons, Ltd.

  9. The Role of Odor-Evoked Memory in Psychological and Physiological Health.

    Herz, Rachel S

    2016-07-19

    This article discusses the special features of odor-evoked memory and the current state-of-the-art in odor-evoked memory research to show how these unique experiences may be able to influence and benefit psychological and physiological health. A review of the literature leads to the conclusion that odors that evoke positive autobiographical memories have the potential to increase positive emotions, decrease negative mood states, disrupt cravings, and reduce physiological indices of stress, including systemic markers of inflammation. Olfactory perception factors and individual difference characteristics that would need to be considered in therapeutic applications of odor-evoked-memory are also discussed. This article illustrates how through the experimentally validated mechanisms of odor-associative learning and the privileged neuroanatomical relationship that exists between olfaction and the neural substrates of emotion, odors can be harnessed to induce emotional and physiological responses that can improve human health and wellbeing.

  10. Evidence that 5-hydroxytryptamine3 receptors mediate cytotoxic drug and radiation-evoked emesis

    Miner, W.D.; Sanger, G.J.; Turner, D.H.

    1987-01-01

    The involvement of 5-hydroxytryptamine (5-HT) 5-HT 3 receptors in the mechanisms of severe emesis evoked by cytotoxic drugs or by total body irradiation have been studied in ferrets. Anti-emetic compounds tested were domperidone (a dopamine antagonist), metoclopramide (a gastric motility stimulant and dopamine antagonist at conventional doses, a 5-HT 3 receptor antagonist at higher doses) and BRL 24924 (a potent gastric motility stimulant and a 5-HT 3 receptor antagonist). Domperidone or metoclopramide prevented apomorphine-evoked emesis, whereas BRL 24924 did not. Similar doses of domperidone did not prevent emesis evoked by cis-platin or by total body irradiation, whereas metoclopramide or BRL 24924 greatly reduced or prevented these types of emesis. Metoclopramide and BRL 24924 also prevented emesis evoked by a combination of doxorubicin and cyclophosphamide. These results are discussed in terms of a fundamental role for 5-HT 3 receptors in the mechanisms mediating severely emetogenic cancer treatment therapies. (author)

  11. Quantifying interhemispheric symmetry of somatosensory evoked potentials with the intraclass correlation coefficient

    van de Wassenberg, Wilma J. G.; van der Hoeven, Johannes H.; Leenders, Klaus L.; Maurits, Natasha M.

    Although large intersubject variability is reported for cortical somatosensory evoked potentials (SEPs), variability between hemispheres within one subject is thought to be small. Therefore, interhemispheric comparison of SEP waveforms might be clinically useful to detect unilateral abnormalities in

  12. The Role of Odor-Evoked Memory in Psychological and Physiological Health

    Rachel S. Herz

    2016-07-01

    Full Text Available This article discusses the special features of odor-evoked memory and the current state-of-the-art in odor-evoked memory research to show how these unique experiences may be able to influence and benefit psychological and physiological health. A review of the literature leads to the conclusion that odors that evoke positive autobiographical memories have the potential to increase positive emotions, decrease negative mood states, disrupt cravings, and reduce physiological indices of stress, including systemic markers of inflammation. Olfactory perception factors and individual difference characteristics that would need to be considered in therapeutic applications of odor-evoked-memory are also discussed. This article illustrates how through the experimentally validated mechanisms of odor-associative learning and the privileged neuroanatomical relationship that exists between olfaction and the neural substrates of emotion, odors can be harnessed to induce emotional and physiological responses that can improve human health and wellbeing.

  13. The ''injection problem'' for quasiparallel shocks

    Zank, G. P.; Rice, W. K. M.; le Roux, J. A.; Cairns, I. H.; Webb, G. M.

    2001-01-01

    For a particle to be accelerated diffusively at a shock by the first-order Fermi acceleration mechanism, the particle must be sufficiently energetic that it can scatter across all the micro- and macrostructure of the shock, experiencing compression between the converging upstream and downstream states. This is the well-known ''injection problem.'' Here the interaction of ions with the ramp of a quasiparallel shock is investigated. Some ions incident on the shock experience specular reflection, caused either by the cross-shock electrostatic potential or by mirroring as the magnetic field is bent and compressed through the ramp. Scattering of reflected ions by self-generated and pre-existing turbulence in the region upstream of the shock then acts to trap backstreaming ions and return them to the ramp, where some experience further reflections. Such repeated reflections and scattering energize a subpopulation of ions up to energies sufficiently large that they can be diffusively shock accelerated. Two ion distributions are considered: pickup ions which are assumed to be described by a shell distribution, are thermal solar wind ions which may be described by a kappa distribution. Injection efficiencies are found analytically to be very high for pickup ions and much lower for thermal solar wind ions, suggesting that this injection mechanism, stochastic reflected ion or SRI acceleration, is a natural precursor for the acceleration of the anomalous cosmic ray component at a quasiparallel shock. While significantly less efficient, SRI acceleration is also viable for thermal solar wind ions described by a kappa distribution

  14. PRECURSORS TO INTERSTELLAR SHOCKS OF SOLAR ORIGIN

    Gurnett, D. A.; Kurth, W. S. [University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242 (United States); Stone, E. C.; Cummings, A. C. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Krimigis, S. M.; Decker, R. B. [Applied Physics Laboratory/JHU, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Ness, N. F. [Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064 (United States); Burlaga, L. F., E-mail: donald-gurnett@uiowa.edu [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States)

    2015-08-20

    On or about 2012 August 25, the Voyager 1 spacecraft crossed the heliopause into the nearby interstellar plasma. In the nearly three years that the spacecraft has been in interstellar space, three notable particle and field disturbances have been observed, each apparently associated with a shock wave propagating outward from the Sun. Here, we present a detailed analysis of the third and most impressive of these disturbances, with brief comparisons to the two previous events, both of which have been previously reported. The shock responsible for the third event was first detected on 2014 February 17 by the onset of narrowband radio emissions from the approaching shock, followed on 2014 May 13 by the abrupt appearance of intense electron plasma oscillations generated by electrons streaming outward ahead of the shock. Finally, the shock arrived on 2014 August 25, as indicated by a jump in the magnetic field strength and the plasma density. Various disturbances in the intensity and anisotropy of galactic cosmic rays were also observed ahead of the shock, some of which are believed to be caused by the reflection and acceleration of cosmic rays by the magnetic field jump at the shock, and/or by interactions with upstream plasma waves. Comparisons to the two previous weaker events show somewhat similar precursor effects, although differing in certain details. Many of these effects are very similar to those observed in the region called the “foreshock” that occurs upstream of planetary bow shocks, only on a vastly larger spatial scale.

  15. Corporate Policies with Permanent and Transitory Shocks

    J-P. Decamps (Jean-Paul); S. Gryglewicz (Sebastian); E. Morellec (Erwan); S. Villeneuve (Stephane)

    2016-01-01

    textabstractWe model the financing, cash holdings, and hedging policies of a firm facing financing frictions and subject to permanent and transitory cash flow shocks. We show that permanent and transitory shocks generate distinct, sometimes opposite, effects on corporate policies and use the model

  16. Shock dynamics in layered periodic media

    Ketcheson, David I.; Leveque, Randall J.

    2012-01-01

    of shock waves in a one-dimensional periodic layered medium by a computational study of time-reversibility and entropy evolution. We find that periodic layered media tend to inhibit shock formation. For small initial conditions and large impedance variation

  17. Particle acceleration and shock wave structure

    DRURY, L.O'C.

    1989-01-01

    A significant determinant in the large-scale structure and evolution of strong collisionless shocks under astrophysical conditions is probably the acceleration of charged particles. The reaction of these particles on the dynamical structure of the shock wave is discussed both theoretically and in the light of recent numerical calculations. Astrophysical implications for the evolution of supernova remnants, are considered. (author). 15 refs

  18. Laser shock wave and its applications

    Yang, Chaojun; Zhang, Yongkang; Zhou, Jianzhong; Zhang, Fang; Feng, Aixin

    2007-12-01

    The technology of laser shock wave is used to not only surface modification but also metal forming. It can be divided into three parts: laser shock processing, laser shock forming (LSF) and laser peenforming(LPF). Laser shock processing as a surface treatment to metals can make engineering components have a residual compressive stress so that it obviously improves their fatigue strength and stress corrosion performances, while laser shock forming (LSF) is a novel technique that is used in plastic deformation of sheet metal recently and Laser peen forming (LPF) is another new sheet metal forming process presented in recent years. They all can be carried out by a high-power and repetition pulse Nd:Glass laser device made by Jiangsu University. Laser shock technology has characterized of ultrahigh pressure and high strain rate (10 6 - 10 7s -1). Now, for different materials, we are able to form different metals to contours and shapes and simultaneity leave their surfaces in crack-resistant compressive stress state. The results show that the technology of laser shock wave can strengthen surface property and prolong fatigue life and especially can deform metals to shapes that could not be adequately made using conventional methods. With the development of the technology of laser shock wave, the applied fields of laser will become greater and greater.

  19. Introduction to Shock Waves and Shock Wave Research

    Anderson, William Wyatt [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-02

    M-9 and a number of other organizations at LANL and elsewhere study materials in dynamic processes. Often, this is described as “shock wave research,” but in reality is broader than is implied by that term. Most of our work is focused on dynamic compression and associated phenomena, but you will find a wide variety of things we do that, while related, are not simple compression of materials, but involve a much richer variety of phenomena. This tutorial will introduce some of the underlying physics involved in this work, some of the more common types of phenomena we study, and common techniques. However, the list will not be exhaustive by any means.

  20. Role of Active Listening and Listening Effort on Contralateral Suppression of Transient Evoked Otoacousic Emissions

    Kalaiah, Mohan Kumar; Theruvan, Nikhitha B; Kumar, Kaushlendra; Bhat, Jayashree S

    2017-01-01

    Background and Objectives The present study aimed to investigate the effect of active listening and listening effort on the contralateral suppression of transient evoked otoacoustic emissions (CSTEOAEs). Subjects and Methods Twenty eight young adults participated in the study. Transient evoked otoacoustic emissions (TEOAEs) were recorded using ?linear? clicks at 60 dB peSPL, in three contralateral noise conditions. In condition 1, TEOAEs were obtained in the presence of white noise in the con...

  1. Awareness during anaesthesia for surgery requiring evoked potential monitoring: A pilot study

    Pritish J Korula

    2017-01-01

    Full Text Available Background: Evoked potential monitoring such as somatosensory-evoked potential (SSEP or motor-evoked potential (MEP monitoring during surgical procedures in proximity to the spinal cord requires minimising the minimum alveolar concentrations (MACs below the anaesthetic concentrations normally required (1 MAC to prevent interference in amplitude and latency of evoked potentials. This could result in awareness. Our primary objective was to determine the incidence of awareness while administering low MAC inhalational anaesthetics for these unique procedures. The secondary objective was to assess the adequacy of our anaesthetic technique from neurophysiologist′s perspective. Methods: In this prospective observational pilot study, 61 American Society of Anesthesiologists 1 and 2 patients undergoing spinal surgery for whom intraoperative evoked potential monitoring was performed were included; during the maintenance phase, 0.7-0.8 MAC of isoflurane was targeted. We evaluated the intraoperative depth of anaesthesia using a bispectral (BIS index monitor as well as the patients response to surgical stimulus (PRST scoring system. Post-operatively, a modified Bruce questionnaire was used to verify awareness. The adequacy of evoked potential readings was also assessed. Results: Of the 61 patients, no patient had explicit awareness. Intraoperatively, 19 of 61 patients had a BIS value of above sixty at least once, during surgery. There was no correlation with PRST scoring and BIS during surgery. Fifty-four out of 61 patient′s evoked potential readings were deemed ′good′ or ′fair′ for the conduct of electrophysiological monitoring. Conclusions: This pilot study demonstrates that administering low MAC inhalational anaesthetics to facilitate evoked potential monitoring does not result in explicit awareness. However, larger studies are needed to verify this. The conduct of SSEP electrophysiological monitoring was satisfactory with the use of this

  2. The effect of digital signage on shoppers’ behavior: the role of the evoked experience

    Dennis, Charles; Brakus, J. Joško; Gupta, Suraksha; Alamanos, Eleftherios

    2014-01-01

    This paper investigates the role of digital signage as experience provider in retail spaces. The findings of a survey-based field experiment demonstrate that digital signage content high on sensory cues evokes affective experience and strengthens customers' experiential processing route. In contrast, digital signage messages high on “features and benefits” information evoke intellectual experience and strengthen customers' deliberative processing route. The affective experience is more strong...

  3. Skinfold thickness affects the isometric knee extension torque evoked by Neuromuscular Electrical Stimulation.

    Medeiros, Flávia V A; Vieira, Amilton; Carregaro, Rodrigo L; Bottaro, Martim; Maffiuletti, Nicola A; Durigan, João L Q

    2015-01-01

    Subcutaneous adipose tissue may influence the transmission of electrical stimuli through to the skin, thus affecting both evoked torque and comfort perception associated with neuromuscular electrical stimulation (NMES). This could seriously affect the effectiveness of NMES for either rehabilitation or sports purposes. To investigate the effects of skinfold thickness (SFT) on maximal NMES current intensity, NMES-evoked torque, and NMES-induced discomfort. First, we compared NMES current intensity, NMES-induced discomfort, and NMES-evoked torque between two subgroups of subjects with thicker (n=10; 20.7 mm) vs. thinner (n=10; 29.4 mm) SFT. Second, we correlated SFT to NMES current intensity, NMES-induced discomfort, and NMES-evoked knee extension torque in 20 healthy women. The NMES-evoked torque was normalized to the maximal voluntary contraction (MVC) torque. The discomfort induced by NMES was assessed with a visual analog scale (VAS). NMES-evoked torque was 27.5% lower in subjects with thicker SFT (p=0.01) while maximal current intensity was 24.2% lower in subjects with thinner SFT (p=0.01). A positive correlation was found between current intensity and SFT (r=0.540, p=0.017). A negative correlation was found between NMES-evoked torque and SFT (r=-0.563, p=0.012). No significant correlation was observed between discomfort scores and SFT (rs=0.15, p=0.53). These results suggest that the amount of subcutaneous adipose tissue (as reflected by skinfold thickness) affected NMES current intensity and NMES-evoked torque, but had no effect on discomfort perception. Our findings may help physical therapists to better understand the impact of SFT on NMES and to design more rational stimulation strategies.

  4. Newborn hearing screening with transient evoked otoacoustic emissions and automatic auditory brainstem response

    Renata Mota Mamede de Carvallo; Carla Gentile Matas; Isabela de Souza Jardim

    2008-01-01

    Objective: The aim of the present investigation was to check Transient Evoked Otoacoustic Emissions and Automatic Auditory Brainstem Response tests applied together in regular nurseries and Newborn Intensive Care Units (NICU), as well as to describe and compare the results obtained in both groups. Methods: We tested 150 newborns from regular nurseries and 70 from NICU. Rresults: The newborn hearing screening results using Transient Evoked Otoacoustic Emissions and Automatic Auditory Brainstem...

  5. Shock loading predictions from application of indicial theory to shock-turbulence interactions

    Keefe, Laurence R.; Nixon, David

    1991-01-01

    A sequence of steps that permits prediction of some of the characteristics of the pressure field beneath a fluctuating shock wave from knowledge of the oncoming turbulent boundary layer is presented. The theory first predicts the power spectrum and pdf of the position and velocity of the shock wave, which are then used to obtain the shock frequency distribution, and the pdf of the pressure field, as a function of position within the interaction region. To test the validity of the crucial assumption of linearity, the indicial response of a normal shock is calculated from numerical simulation. This indicial response, after being fit by a simple relaxation model, is used to predict the shock position and velocity spectra, along with the shock passage frequency distribution. The low frequency portion of the shock spectra, where most of the energy is concentrated, is satisfactorily predicted by this method.

  6. Shock-induced devolatilization of calcite

    Boslough, M. B.; Ahrens, T. J.; Vizgirda, J.; Becker, R. H.; Epstein, S.

    1982-01-01

    Experimental measurements of the release adiabats by Vizgirda (1981) indicate that substantial vaporization takes place upon release from shock pressures of 37 GPa for calcite and 14 GPa for aragonite. The present investigation includes the first controlled partial vaporization experiments on calcite. The experiments were conducted to test the predictions of the release adiabat experiments. The quantities of the gaseous species produced from shocked calcite and their carbon and oxygen isotopic compositions were determined, and the shock-induced effect on the Mn(2+) electron spin resonance spectrum in the shock-recovered calcite was observed. On the basis of the obtained results, it is concluded that shock stresses at the 17-18 GPa level give rise to volatilization of 0.03-0.3 (mole) percent of calcite to CO2 and CO. The devolatilization of calcite occurs at low pressure at significantly lower entropy densities than predicted on the basis of thermodynamic continuum models.

  7. Shock waves in helium at low temperatures

    Liepmann, H.W.; Torczynski, J.R.

    1986-01-01

    Results are reported from studies of the properties of low temperature He-4 using shock waves as a probe. Ideal shock tube theory is used to show that sonic speeds of Mach 40 are attainable in He at 300 K. Viscosity reductions at lower temperatures minimize boundary layer effects at the side walls. A two-fluid model is described to account for the phase transition which He undergoes at temperatures below 2.2 K, after which the quantum fluid (He II) and the normal compressed superfluid (He I) coexist. Analytic models are provided for pressure-induced shocks in He I and temperature-induced shock waves (called second sound) which appear in He II. The vapor-fluid interface of He I is capable of reflecting second and gasdynamic sound shocks, which can therefore be used as probes for studying phase transitions between He I and He II. 17 references

  8. Analytical extension of curved shock theory

    Emanuel, G.

    2018-03-01

    Curved shock theory (CST) is limited to shock waves in a steady, two-dimensional or axisymmetric (2-Ax) flow of a perfect gas. A unique feature of CST is its use of intrinsic coordinates that result in an elegant and useful formulation for flow properties just downstream of a shock. For instance, the downstream effect of upstream vorticity, shock wave curvature, and the upstream pressure gradient along a streamline is established. There have been several attempts to extend CST, as mentioned in the text. Removal of the steady, 2-Ax, and perfect gas limitations, singly or in combination, requires an appropriate formulation of the shock wave's jump relations and the intrinsic coordinate Euler equations. Issues discussed include flow plane versus osculating plane, unsteady flow, vorticity, an imperfect gas, etc. The extension of CST utilizes concepts from differential geometry, such as the osculating plane, streamline torsion, and the Serret-Frenet equations.

  9. 28th International Symposium on Shock Waves

    2012-01-01

    The University of Manchester hosted the 28th International Symposium on Shock Waves between 17 and 22 July 2011. The International Symposium on Shock Waves first took place in 1957 in Boston and has since become an internationally acclaimed series of meetings for the wider Shock Wave Community. The ISSW28 focused on the following areas: Blast Waves, Chemically Reacting Flows, Dense Gases and Rarefied Flows, Detonation and Combustion, Diagnostics, Facilities, Flow Visualisation, Hypersonic Flow, Ignition, Impact and Compaction, Multiphase Flow, Nozzle Flow, Numerical Methods, Propulsion, Richtmyer-Meshkov, Shockwave Boundary Layer Interaction, Shock Propagation and Reflection, Shock Vortex Interaction, Shockwave Phenomena and Applications, as well as Medical and Biological Applications. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 28 and individuals interested in these fields.

  10. Barrier experiment: Shock initiation under complex loading

    Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-01-12

    The barrier experiments are a variant of the gap test; a detonation wave in a donor HE impacts a barrier and drives a shock wave into an acceptor HE. The question we ask is: What is the trade-off between the barrier material and threshold barrier thickness to prevent the acceptor from detonating. This can be viewed from the perspective of shock initiation of the acceptor subject to a complex pressure drive condition. Here we consider key factors which affect whether or not the acceptor undergoes a shock-to-detonation transition. These include the following: shock impedance matches for the donor detonation wave into the barrier and then the barrier shock into the acceptor, the pressure gradient behind the donor detonation wave, and the curvature of detonation front in the donor. Numerical simulations are used to illustrate how these factors affect the reaction in the acceptor.

  11. Right hemispheric dominance of visual phenomena evoked by intracerebral stimulation of the human visual cortex.

    Jonas, Jacques; Frismand, Solène; Vignal, Jean-Pierre; Colnat-Coulbois, Sophie; Koessler, Laurent; Vespignani, Hervé; Rossion, Bruno; Maillard, Louis

    2014-07-01

    Electrical brain stimulation can provide important information about the functional organization of the human visual cortex. Here, we report the visual phenomena evoked by a large number (562) of intracerebral electrical stimulations performed at low-intensity with depth electrodes implanted in the occipito-parieto-temporal cortex of 22 epileptic patients. Focal electrical stimulation evoked primarily visual hallucinations with various complexities: simple (spot or blob), intermediary (geometric forms), or complex meaningful shapes (faces); visual illusions and impairments of visual recognition were more rarely observed. With the exception of the most posterior cortical sites, the probability of evoking a visual phenomenon was significantly higher in the right than the left hemisphere. Intermediary and complex hallucinations, illusions, and visual recognition impairments were almost exclusively evoked by stimulation in the right hemisphere. The probability of evoking a visual phenomenon decreased substantially from the occipital pole to the most anterior sites of the temporal lobe, and this decrease was more pronounced in the left hemisphere. The greater sensitivity of the right occipito-parieto-temporal regions to intracerebral electrical stimulation to evoke visual phenomena supports a predominant role of right hemispheric visual areas from perception to recognition of visual forms, regardless of visuospatial and attentional factors. Copyright © 2013 Wiley Periodicals, Inc.

  12. Refractory episodic vertigo: role of intratympanic gentamicin and vestibular evoked myogenic potentials,

    Erika Celis-Aguilar

    Full Text Available Abstract Introduction: Even today, the treatment of intractable vertigo remains a challenge. Vestibular ablation with intratympanic gentamicin stands as a good alternative in the management of refractory vertigo patients. Objective: To control intractable vertigo through complete saccular and horizontal canal vestibular ablation with intratympanic gentamicin treatment. Methods: Patients with refractory episodic vertigo were included. The inclusion criteria were: unilateral ear disease, moderate to profound sensorineural hearing loss, and failure to other treatments. Included patients underwent 0.5-0.8 mL of gentamicin intratympanic application at a 30 mg/mL concentration. Vestibular ablation was confirmed by the absence of response on cervical vestibular evoked myogenic potentials and no response on caloric tests. Audiometry, electronystagmography with iced water, and vestibular evoked myogenic potentials were performed in all patients. Results: Ten patients were included; nine patients with Meniere's disease and one patient with (late onset delayed hydrops. Nine patients showed an absent response on vestibular evoked myogenic potentials and no response on caloric tests. The only patient with low amplitude on cervical vestibular evoked myogenic potentials had vertigo recurrence. Vertigo control was achieved in 90% of the patients. One patient developed hearing loss >30 dB. Conclusions: Cervical vestibular evoked myogenic potentials confirmed vestibular ablation in patients treated with intratympanic gentamicin. High-grade vertigo control was due to complete saccular and horizontal canal ablation (no response to iced water in electronystagmography and no response on cervical vestibular evoked myogenic potentials.

  13. Joint angle affects volitional and magnetically-evoked neuromuscular performance differentially.

    Minshull, C; Rees, D; Gleeson, N P

    2011-08-01

    This study examined the volitional and magnetically-evoked neuromuscular performance of the quadriceps femoris at functional knee joint angles adjacent to full extension. Indices of volitional and magnetically-evoked neuromuscular performance (N=15 healthy males, 23.5 ± 2.9 years, 71.5 ± 5.4 kg, 176.5 ± 5.5 cm) were obtained at 25°, 35° and 45° of knee flexion. Results showed that volitional and magnetically-evoked peak force (PF(V) and P(T)F(E), respectively) and electromechanical delay (EMD(V) and EMD(E), respectively) were enhanced by increased knee flexion. However, greater relative improvements in volitional compared to evoked indices of neuromuscular performance were observed with increasing flexion from 25° to 45° (e.g. EMD(V), EMD(E): 36% vs. 11% improvement, respectively; F([2,14])=6.8, pjoint positions. These findings suggest that the extent of the relative differential between volitional and evoked neuromuscular performance capabilities is joint angle-specific and not correlated with performance capabilities at adjacent angles, but tends to be smaller with increased flexion. As such, effective prediction of volitional from evoked performance capabilities at both analogous and adjacent knee joint positions would lack robustness. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Norepinephrine-evoked pain in fibromyalgia. A randomized pilot study [ISRCTN70707830

    Casanova Jose-Miguel

    2002-01-01

    Full Text Available Abstract Background Fibromyalgia syndrome displays sympathetically maintained pain features such as frequent post-traumatic onset and stimuli-independent pain accompanied by allodynia and paresthesias. Heart rate variability studies showed that fibromyalgia patients have changes consistent with ongoing sympathetic hyperactivity. Norepinephrine-evoked pain test is used to assess sympathetically maintained pain syndromes. Our objective was to define if fibromyalgia patients have norepinephrine-evoked pain. Methods Prospective double blind controlled study. Participants: Twenty FM patients, and two age/sex matched control groups; 20 rheumatoid arthritis patients and 20 healthy controls. Ten micrograms of norepinephrine diluted in 0.1 ml of saline solution were injected in a forearm. The contrasting substance, 0.1 ml of saline solution alone, was injected in the opposite forearm. Maximum local pain elicited during the 5 minutes post-injection was graded on a visual analog scale (VAS. Norepinephrine-evoked pain was diagnosed when norepinephrine injection induced greater pain than placebo injection. Intensity of norepinephrine-evoked pain was calculated as the difference between norepinephrine minus placebo-induced VAS scores. Results Norepinephrine-evoked pain was seen in 80 % of FM patients (95% confidence intervals 56.3 – 94.3%, in 30 % of rheumatoid arthritis patients and in 30 % of healthy controls (95% confidence intervals 11.9 – 54.3 (p Conclusions Fibromyalgia patients have norepinephrine-evoked pain. This finding supports the hypothesis that fibromyalgia may be a sympathetically maintained pain syndrome.

  15. Newborn hearing screening with transient evoked otoacoustic emissions and automatic auditory brainstem response

    Renata Mota Mamede de Carvallo

    2008-09-01

    Full Text Available Objective: The aim of the present investigation was to check Transient Evoked Otoacoustic Emissions and Automatic Auditory Brainstem Response tests applied together in regular nurseries and Newborn Intensive Care Units (NICU, as well as to describe and compare the results obtained in both groups. Methods: We tested 150 newborns from regular nurseries and 70 from NICU. Rresults: The newborn hearing screening results using Transient Evoked Otoacoustic Emissions and Automatic Auditory Brainstem Response tests could be applied to all babies. The “pass” result for the group of babies from the nursery was 94.7% using Transient Evoked Otoacoustic Emissions and 96% using Automatic Auditory Brainstem Response. The newborn intensive care unit group obtained 87.1% on Transient Evoked Otoacoustic Emissions and 80% on the Automatic Auditory Brainstem Response, and there was no statistical difference between the procedures when the groups were evaluated individually. However, comparing the groups, Transient Evoked Otoacoustic Emissions were presented in 94.7% of the nursery babies and in 87.1% in the group from the newborn intensive care unit. Considering the Automatic Auditory Brainstem Response, we found 96 and 87%, respectively. Cconclusions: Transient Evoked Otoacoustic Emissions and Automatic Auditory Brainstem Response had similar “pass” and “fail” results when the procedures were applied to neonates from the regular nursery, and the combined tests were more precise to detect hearing impairment in the newborn intensive care unit babies.

  16. Effect of peripherally and cortically evoked swallows on jaw reflex responses in anesthetized rabbits.

    Suzuki, Taku; Yoshihara, Midori; Sakai, Shogo; Tsuji, Kojun; Nagoya, Kouta; Magara, Jin; Tsujimura, Takanori; Inoue, Makoto

    2018-05-03

    This study aimed to investigate whether the jaw-opening (JOR) and jaw-closing reflexes (JCR) are modulated during not only peripherally, but also centrally, evoked swallowing. Experiments were carried out on 24 adult male Japanese white rabbits. JORs were evoked by trigeminal stimulation at 1 Hz for 30 sec. In the middle 10 sec, either the superior laryngeal nerve (SLN) or cortical swallowing area (Cx) was simultaneously stimulated to evoke swallowing. The peak-to-peak JOR amplitude was reduced during the middle and late 10-sec periods (i.e., during and after SLN or Cx stimulation), and the reduction was dependent on the current intensity of SLN/Cx stimulation: greater SLN/Cx stimulus current resulted in greater JOR inhibition. The reduction rate was significantly greater during Cx stimulation than during SLN stimulation. The amplitude returned to baseline 2 min after 10-sec SLN/Cx stimulation. The effect of co-stimulation of SLN and Cx was significantly greater than that of SLN stimulation alone. There were no significant differences in any parameters of the JCR between conditions. These results clearly showed that JOR responses were significantly suppressed, not only during peripherally evoked swallowing but also during centrally evoked swallowing, and that the inhibitory effect is likely to be larger during centrally compared with peripherally evoked swallowing. The functional implications of these results are discussed. Copyright © 2018. Published by Elsevier B.V.

  17. A comparison of auditory evoked potentials to acoustic beats and to binaural beats.

    Pratt, Hillel; Starr, Arnold; Michalewski, Henry J; Dimitrijevic, Andrew; Bleich, Naomi; Mittelman, Nomi

    2010-04-01

    The purpose of this study was to compare cortical brain responses evoked by amplitude modulated acoustic beats of 3 and 6 Hz in tones of 250 and 1000 Hz with those evoked by their binaural beats counterparts in unmodulated tones to indicate whether the cortical processes involved differ. Event-related potentials (ERPs) were recorded to 3- and 6-Hz acoustic and binaural beats in 2000 ms duration 250 and 1000 Hz tones presented with approximately 1 s intervals. Latency, amplitude and source current density estimates of ERP components to beats-evoked oscillations were determined and compared across beat types, beat frequencies and base (carrier) frequencies. All stimuli evoked tone-onset components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude in response to acoustic than to binaural beats, to 250 than to 1000 Hz base frequency and to 3 Hz than to 6 Hz beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left temporal lobe areas. Differences between estimated sources of potentials to acoustic and binaural beats were not significant. The perceptions of binaural beats involve cortical activity that is not different than acoustic beats in distribution and in the effects of beat- and base frequency, indicating similar cortical processing. Copyright 2010 Elsevier B.V. All rights reserved.

  18. Small-Scale Shock Testing of Propellants and Ingredients

    Dawley, S

    2004-01-01

    .... The use of small-scale gap testing to evaluate the shock sensitivity of individual propellant ingredients and propellant formulations is a valuable method for experimentally establishing shock...

  19. Surface instabilities in shock loaded granular media

    Kandan, K.; Khaderi, S. N.; Wadley, H. N. G.; Deshpande, V. S.

    2017-12-01

    The initiation and growth of instabilities in granular materials loaded by air shock waves are investigated via shock-tube experiments and numerical calculations. Three types of granular media, dry sand, water-saturated sand and a granular solid comprising PTFE spheres were experimentally investigated by air shock loading slugs of these materials in a transparent shock tube. Under all shock pressures considered here, the free-standing dry sand slugs remained stable while the shock loaded surface of the water-saturated sand slug became unstable resulting in mixing of the shocked air and the granular material. By contrast, the PTFE slugs were stable at low pressures but displayed instabilities similar to the water-saturated sand slugs at higher shock pressures. The distal surfaces of the slugs remained stable under all conditions considered here. Eulerian fluid/solid interaction calculations, with the granular material modelled as a Drucker-Prager solid, reproduced the onset of the instabilities as seen in the experiments to a high level of accuracy. These calculations showed that the shock pressures to initiate instabilities increased with increasing material friction and decreasing yield strain. Moreover, the high Atwood number for this problem implied that fluid/solid interaction effects were small, and the initiation of the instability is adequately captured by directly applying a pressure on the slug surface. Lagrangian calculations with the directly applied pressures demonstrated that the instability was caused by spatial pressure gradients created by initial surface perturbations. Surface instabilities are also shown to exist in shock loaded rear-supported granular slugs: these experiments and calculations are used to infer the velocity that free-standing slugs need to acquire to initiate instabilities on their front surfaces. The results presented here, while in an idealised one-dimensional setting, provide physical understanding of the conditions required to

  20. Economy. The Japanese shock wave

    Lecompte-Boinet, G.; Dupin, L.; Chandes, C.; Gateaud, P.; Guez, L.; Maillard, C.

    2011-01-01

    Several articles analyse and comment the consequences of the earthquake which occurred in Japan, not only for the Japanese industry and economy, but also for the French ones. In Japan, the most impacted sectors are the energy, the semiconductor and the automotive industries. Renewable energies and gas will at least temporarily replace nuclear energy. Other countries will be impacted, notably China and its automotive industry due to a lack of components. There will also be a lack of electronic components because Japan represents, directly or indirectly, about 40 per cent of world production in this field. In some regions of Japan, the whole production system is in danger because of the supply chain organisation. Other sectors are concerned for differing reasons: raw materials, aeronautic construction, luxury and cosmetics. An article evokes initiatives of French company chairmen, personnel and trade unions to help Japan and the Japanese. An article describes the development of robots and unmanned vehicles by French companies, which are able to intervene in radioactive environments. Another consequence is the inspection of the French and European nuclear plants in order to see whether they can withstand extreme risks. An article stresses that several French industrial sites are exposed to natural risks (earthquake, floods). Finally, Daniel Cohn-Bendit stresses that, after Fukushima, the unlikely is not impossible any longer

  1. [Visual evoked potentials in management of amblyopia in children].

    Gromová, M; Gerinec, A

    2010-11-01

    The authors want to point out the possibility of using the visual evoked potentials (VEP) in the diagnostic process of amblyopia, especially in preverbal children. We also researched the possibility of screening for amblyopia with VEP in young patients with anisometropia without strabismus being present, especially those who come from affected families. The authors followed changes in the course of an occlusion therapy and suggest that VEP could be used to predict a success of the amblyopia therapy. We analyzed group of 45 pediatric patients ages 2-10 years who were investigated in years 2006-2009 at Pediatric Ophthalmology Department of Children University Hospital in Bratislava with amblyopia. This group was compared with a control group of 25 healthy children. The cause of amblyopia in a majority of children (29 patients) was hyperopic anisometropia, 13 children had hyperopic isometropia, 3 patients had myopia over -3D. These causes in 22 children were combined with strabismus. The monocular pattern of VEP was evaluated in all patients. In cooperative children (25) we also evaluated binocular pattern of VEP. 18 patients with amblyopia had a second VEP evaluation done during the occlusion therapy, among those were 23 amblyopic eyes. The time frame from the first VEP evaluation to the second VEP evaluation was 1-11 months, average 5,1 months. The material was statistically evaluated. Our study showed statistically significant prolongation of the latency of both P and N2 waves (p = 0.01) in children with amblyopia.This can be used in diagnostic process of amblyopia in preverbal children as well as in the screening for amblyopia. We also followed changes during the occlusion therapy and we discovered persistent prolongation of the latency of the P wave and also changes in the amplitudes (p = 0.05) During repeated measurements and with applied therapy one can follow the dynamics of amblyopia, course of therapy by VEP changes. Results of our research suggest a great

  2. Effects of Atwood number on shock focusing in shock-cylinder interaction

    Ou, Junfeng; Ding, Juchun; Luo, Xisheng; Zhai, Zhigang

    2018-02-01

    The evolution of shock-accelerated heavy-gas cylinder surrounded by the air with different Atwood numbers (A_t=0.28, 0.50, 0.63) is investigated, concentrating on shock focusing and jet formation. Experimentally, a soap film technique is used to generate an ideal two-dimensional discontinuous gas cylinder with a clear surface, which can guarantee the observation of shock wave movements inside the cylinder. Different Atwood numbers are realized by different mixing ratios of SF_6 and air inside the cylinder. A high-speed schlieren system is adopted to capture the shock motions and jet morphology. Numerical simulations are also performed to provide more information. The results indicate that an inward jet is formed for low Atwood numbers, while an outward jet is generated for high Atwood numbers. Different Atwood numbers will lead to the differences in the relative velocities between the incident shock and the refraction shock, which ultimately results in the differences in shock competition near the downstream pole. The morphology and feature of the jet are closely associated with the position and intensity of shock focusing. The pressure and vorticity contours indicate that the jet formation should be attributed to the pressure pulsation caused by shock focusing, and the jet development is ascribed to the vorticity induction. Finally, a time ratio proposed in the previous work for determining the shock-focusing type is verified by experiments.

  3. Shock Mechanism Analysis and Simulation of High-Power Hydraulic Shock Wave Simulator

    Xiaoqiu Xu

    2017-01-01

    Full Text Available The simulation of regular shock wave (e.g., half-sine can be achieved by the traditional rubber shock simulator, but the practical high-power shock wave characterized by steep prepeak and gentle postpeak is hard to be realized by the same. To tackle this disadvantage, a novel high-power hydraulic shock wave simulator based on the live firing muzzle shock principle was proposed in the current work. The influence of the typical shock characteristic parameters on the shock force wave was investigated via both theoretical deduction and software simulation. According to the obtained data compared with the results, in fact, it can be concluded that the developed hydraulic shock wave simulator can be applied to simulate the real condition of the shocking system. Further, the similarity evaluation of shock wave simulation was achieved based on the curvature distance, and the results stated that the simulation method was reasonable and the structural optimization based on software simulation is also beneficial to the increase of efficiency. Finally, the combination of theoretical analysis and simulation for the development of artillery recoil tester is a comprehensive approach in the design and structure optimization of the recoil system.

  4. A Prognostic Model for Development of Profound Shock among Children Presenting with Dengue Shock Syndrome.

    Phung Khanh Lam

    Full Text Available To identify risk factors and develop a prediction model for the development of profound and recurrent shock amongst children presenting with dengue shock syndrome (DSS.We analyzed data from a prospective cohort of children with DSS recruited at the Paediatric Intensive Care Unit of the Hospital for Tropical Disease in Ho Chi Minh City, Vietnam. The primary endpoint was "profound DSS", defined as ≥2 recurrent shock episodes (for subjects presenting in compensated shock, or ≥1 recurrent shock episodes (for subjects presenting initially with decompensated/hypotensive shock, and/or requirement for inotropic support. Recurrent shock was evaluated as a secondary endpoint. Risk factors were pre-defined clinical and laboratory variables collected at the time of presentation with shock. Prognostic model development was based on logistic regression and compared to several alternative approaches.The analysis population included 1207 children of whom 222 (18% progressed to "profound DSS" and 433 (36% had recurrent shock. Independent risk factors for both endpoints included younger age, earlier presentation, higher pulse rate, higher temperature, higher haematocrit and, for females, worse hemodynamic status at presentation. The final prognostic model for "profound DSS" showed acceptable discrimination (AUC=0.69 for internal validation and calibration and is presented as a simple score-chart.Several risk factors for development of profound or recurrent shock among children presenting with DSS were identified. The score-chart derived from the prognostic models should improve triage and management of children presenting with DSS in dengue-endemic areas.

  5. Heat shock proteins of higher plants

    Key, J.L.; Lin, C.Y.; Chen, Y.M.

    1981-01-01

    The pattern of protein synthesis changes rapidly and dramatically when the growth temperture of soybean seedling tissue is increased from 28 0 C (normal) to about 40 0 C (heat shock). The synthesis of normal proteins is greatly decreased and a new set of proteins, heat shock proteins, is induced. The heat shock proteins of soybean consist of 10 new bands on one-dimensional NaDodSO 4 gels; a more complex pattern is observed on two-dimensional gels. when the tissue is returned to 28 0 C after 4 hr at 40 0 C, there is progressive decline in the synthesis of heat shock proteins and reappearance of a normal pattern of synthesis by 3 or 4 hr. In vitro translation of poly(A) + RNAs isolated from tissued grown at 28 and 40 0 C shows that the heat shock proteins are translated from a ndw set of mRNAs induced at 40 0 C; furthermore, the abundant class mRNAs for many of the normal proteins persist even though they are translated weakly (or not at all) in vivo at 40 or 42.5 0 C. The heat shock response in soybean appears similar to the much-studied heat shock phenomenon in Drosophila

  6. Overview of shock waves in medicine

    Cleveland, Robin O.

    2003-10-01

    A brief overview of three applications of shock waves is presented. Shock wave lithotripsy (SWL) has been in clinical use for more than 20 years. In the United States it is used to treat more than 80% of kidney stone cases and has wide acceptance with patients because it is a noninvasive procedure. Despite SWLs enormous success there is no agreement on how shock waves comminute stones. There is also a general acceptance that shock waves lead to trauma to the soft tissue of the kidney. Yet there has been little forward progress in developing lithotripters which provide comminution with less side-effects, indeed the original machine is still considered the gold standard. The last decade has seen the advent of new shock wave devices for treating principally musculoskeletal indications, such as plantar fasciitis, tennis elbow, and bone fractures that do not heal. This is referred to as shock wave therapy (SWT). The mechanisms by which SWT works are even less well understood than SWL and the consequences of bioeffects have also not been studied in detail. Shock waves have also been shown to be effective at enhancing drug delivery into cells and assisting with gene transfection. [Work partially supported by NIH.

  7. Structure of Energetic Particle Mediated Shocks Revisited

    Mostafavi, P.; Zank, G. P.; Webb, G. M.

    2017-01-01

    The structure of collisionless shock waves is often modified by the presence of energetic particles that are not equilibrated with the thermal plasma (such as pickup ions [PUIs] and solar energetic particles [SEPs]). This is relevant to the inner and outer heliosphere and the Very Local Interstellar Medium (VLISM), where observations of shock waves (e.g., in the inner heliosphere) show that both the magnetic field and thermal gas pressure are less than the energetic particle component pressures. Voyager 2 observations revealed that the heliospheric termination shock (HTS) is very broad and mediated by energetic particles. PUIs and SEPs contribute both a collisionless heat flux and a higher-order viscosity. We show that the incorporation of both effects can completely determine the structure of collisionless shocks mediated by energetic ions. Since the reduced form of the PUI-mediated plasma model is structurally identical to the classical cosmic ray two-fluid model, we note that the presence of viscosity, at least formally, eliminates the need for a gas sub-shock in the classical two-fluid model, including in that regime where three are possible. By considering parameters upstream of the HTS, we show that the thermal gas remains relatively cold and the shock is mediated by PUIs. We determine the structure of the weak interstellar shock observed by Voyager 1 . We consider the inclusion of the thermal heat flux and viscosity to address the most general form of an energetic particle-thermal plasma two-fluid model.

  8. Impaired Fracture Healing after Hemorrhagic Shock

    Philipp Lichte

    2015-01-01

    Full Text Available Impaired fracture healing can occur in severely injured patients with hemorrhagic shock due to decreased soft tissue perfusion after trauma. We investigated the effects of fracture healing in a standardized pressure controlled hemorrhagic shock model in mice, to test the hypothesis that bleeding is relevant in the bone healing response. Male C57/BL6 mice were subjected to a closed femoral shaft fracture stabilized by intramedullary nailing. One group was additionally subjected to pressure controlled hemorrhagic shock (HS, mean arterial pressure (MAP of 35 mmHg for 90 minutes. Serum cytokines (IL-6, KC, MCP-1, and TNF-α were analyzed 6 hours after shock. Fracture healing was assessed 21 days after fracture. Hemorrhagic shock is associated with a significant increase in serum inflammatory cytokines in the early phase. Histologic analysis demonstrated a significantly decreased number of osteoclasts, a decrease in bone quality, and more cartilage islands after hemorrhagic shock. μCT analysis showed a trend towards decreased bone tissue mineral density in the HS group. Mechanical testing revealed no difference in tensile failure. Our results suggest a delay in fracture healing after hemorrhagic shock. This may be due to significantly diminished osteoclast recruitment. The exact mechanisms should be studied further, particularly during earlier stages of fracture healing.

  9. Structure of Energetic Particle Mediated Shocks Revisited

    Mostafavi, P.; Zank, G. P. [Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Webb, G. M. [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2017-05-20

    The structure of collisionless shock waves is often modified by the presence of energetic particles that are not equilibrated with the thermal plasma (such as pickup ions [PUIs] and solar energetic particles [SEPs]). This is relevant to the inner and outer heliosphere and the Very Local Interstellar Medium (VLISM), where observations of shock waves (e.g., in the inner heliosphere) show that both the magnetic field and thermal gas pressure are less than the energetic particle component pressures. Voyager 2 observations revealed that the heliospheric termination shock (HTS) is very broad and mediated by energetic particles. PUIs and SEPs contribute both a collisionless heat flux and a higher-order viscosity. We show that the incorporation of both effects can completely determine the structure of collisionless shocks mediated by energetic ions. Since the reduced form of the PUI-mediated plasma model is structurally identical to the classical cosmic ray two-fluid model, we note that the presence of viscosity, at least formally, eliminates the need for a gas sub-shock in the classical two-fluid model, including in that regime where three are possible. By considering parameters upstream of the HTS, we show that the thermal gas remains relatively cold and the shock is mediated by PUIs. We determine the structure of the weak interstellar shock observed by Voyager 1 . We consider the inclusion of the thermal heat flux and viscosity to address the most general form of an energetic particle-thermal plasma two-fluid model.

  10. Shock propagation in a heterogeneous medium

    Elbaz, D.

    2011-01-01

    In the frame of the inertial confinement fusion in direct drive, the use of foams as ablator allows the reduction of hydrodynamic instabilities created on the target by the direct laser irradiation. The foam is made up of carbon (CH) fibers impregnated of cryogenic deuterium-tritium (DT). In the past, studies have been carried out considering this foam to be a homogeneous medium. Yet, the foam presents heterogeneous features. We study the effects of this heterogeneity on the shock velocity when the laser irradiates the target. Thanks to experimental and numerical studies, we show that the shock propagates faster in the heterogeneous medium than in the homogeneous one with the same averaged density. This velocity gap depends on the presence rate of the CH fibers in the foam, the density ratio, the adiabatic coefficient and the foam geometry. We model the foam by different ways, more and more complex. The shock velocity modification is due to the baroclinicity which, during the interaction between the shock front and the interface, creates a vorticity deposition, responsible for the shock acceleration. Accordingly, an interface, which is plane and perpendicular to the front shock, maximizes the vorticity deposition and increases the velocity gaps between heterogeneous and homogeneous media. We found a correlation between the kinetic energy behind the shock front and the velocities relative difference. We compared our results with two analytical models. However, the system is not closed, so we can't for the moment develop a predictive model. (author) [fr

  11. Energetics of the terrestrial bow shock

    Hamrin, Maria; Gunell, Herbert; Norqvist, Patrik

    2017-04-01

    The solar wind is the primary energy source for the magnetospheric energy budget. Energy can enter through the magnetopause both as kinetic energy (plasma entering via e.g. magnetic reconnection and impulsive penetration) and as electromagnetic energy (e.g. by the conversion of solar wind kinetic energy into electromagnetic energy in magnetopause generators). However, energy is extracted from the solar wind already at the bow shock, before it encounters the terrestrial magnetopause. At the bow shock the supersonic solar wind is slowed down and heated, and the region near the bow shock is known to host many complex processes, including the accelerating of particles and the generation of waves. The processes at and near the bow shock can be discussed in terms of energetics: In a generator (load) process kinetic energy is converted to (from) electromagnetic energy. Bow shock regions where the solar wind is decelerated correspond to generators, while regions where particles are energized (accelerated and heated) correspond to loads. Recently, it has been suggested that currents from the bow shock generator should flow across the magnetosheath and connect to the magnetospause current systems [Siebert and Siscoe, 2002; Lopez et al., 2011]. In this study we use data from the Magnetospheric MultiScale (MMS) mission to investigate the energetics of the bow shock and the current closure, and we compare with the MHD simulations of Lopez et al., 2011.

  12. Radiative shocks with electron thermal conduction

    Borkowski, Kazimierz.

    1988-01-01

    The authors studies the influence of electron thermal conduction on radiative shock structure for both one- and two-temperature plasmas. The dimensionless ratio of the conductive length to the cooling length determines whether or not conduction is important, and shock jump conditions with conduction are established for a collisionless shock front. He obtains approximate solutions with the assumptions that the ionization state of the gas is constant and the cooling rate is a function of temperature alone. In the absence of magnetic fields, these solutions indicate that conduction noticeably influences normal-abundance interstellar shocks with velocities 50-100 km s -1 and dramatically affects metal-dominated shocks over a wide range of shock velocities. Magnetic fields inhibit conduction, but the conductive energy flux and the corresponding decrease in the post-shock electron temperature may still be appreciable. He calculates detailed steady-state radiative shock models in gas composed entirely of oxygen, with the purpose of explaining observations of fast-moving knots in Cas A and other oxygen-rich supernova remnants (SNRs). The O III ion, whose forbidden emission usually dominates the observed spectra, is present over a wide range of shock velocities, from 100 to 170 kms -1 . All models with conduction have extensive warm photoionization zones, which provides better agreement with observed optical (O I) line strengths. However, the temperatures in these zones could be lowered by (Si II) 34.8 μm and (Ne II) 12.8 μm cooling if Si and Ne are present in appreciable abundance relative to O. Such low temperatures would be inconsistent with the observed (O I) emission in oxygen-rich SNRs

  13. Clinical and evoked pain, personality traits, and emotional states: can familial confounding explain the associations?

    Strachan, Eric; Poeschla, Brian; Dansie, Elizabeth; Succop, Annemarie; Chopko, Laura; Afari, Niloofar

    2015-01-01

    Pain is a complex phenomenon influenced by context and person-specific factors. Affective dimensions of pain involve both enduring personality traits and fleeting emotional states. We examined how personality traits and emotional states are linked with clinical and evoked pain in a twin sample. 99 female twin pairs were evaluated for clinical and evoked pain using the McGill Pain Questionnaire (MPQ) and dolorimetry, and completed the 120-item International Personality Item Pool (IPIP), the Positive and Negative Affect Scale (PANAS), and ratings of stress and mood. Using a co-twin control design we examined a) the relationship of personality traits and emotional states with clinical and evoked pain and b) whether genetics and common environment (i.e. familial factors) may account for the associations. Neuroticism was associated with the sensory component of the MPQ; this relationship was not confounded by familial factors. None of the emotional state measures was associated with the MPQ. PANAS negative affect was associated with lower evoked pressure pain threshold and tolerance; these associations were confounded by familial factors. There were no associations between IPIP traits and evoked pain. A relationship exists between neuroticism and clinical pain that is not confounded by familial factors. There is no similar relationship between negative emotional states and clinical pain. In contrast, the relationship between negative emotional states and evoked pain is strong while the relationship with enduring personality traits is weak. The relationship between negative emotional states and evoked pain appears to be non-causal and due to familial factors. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. DSMC Computations for Regions of Shock/Shock and Shock/Boundary Layer Interaction

    Moss, James N.

    2001-01-01

    This paper presents the results of a numerical study of hypersonic interacting flows at flow conditions that include those for which experiments have been conducted in the Calspan-University of Buffalo Research Center (CUBRC) Large Energy National Shock (LENS) tunnel and the ONERA R5Ch low-density wind tunnel. The computations are made with the direct simulation Monte Carlo (DSMC) method of Bird. The focus is on Mach 9.3 to 11.4 flows about flared axisymmetric configurations, both hollow cylinder flares and double cones. The results presented highlight the sensitivity of the calculations to grid resolution, provide results concerning the conditions for incipient separation, and provide information concerning the flow structure and surface results for the extent of separation, heating, pressure, and skin friction.

  15. Temperature measurements of shock-compressed deuterium

    Holmes, N.C.; Ross, M.; Nellis, W.J.

    1994-11-01

    The authors measured the temperatures of single and double-shocked D 2 and H 2 up to 85 GPa (0.85 Mbar) and 5,200 K. While single shock temperatures, at pressures to 23 GPa, agree well with previous models, the double shock temperatures are as much as 40% lower than predicted. This is believed to be caused by molecular dissociation, and a new model of the hydrogen EOS at extreme conditions has been developed which correctly predicts their observations. These data and model have important implications for programs which use condensed-phase hydrogen in implosion systems

  16. Recent oil price shock and Tunisian economy

    Jbir, Rafik; Zouari-Ghorbel, Sonia

    2009-01-01

    The objective of this paper is to study the oil prices-macroeconomy relationship by the analysis of the role of subsidy policy. The vector autoregression (VAR) method was employed to analyze the data over the period 1993 Q1 - 2007 Q3. The results of the model using both linear and non-linear specifications indicate that there is no direct impact of oil price shock on the economic activity. The shock of oil prices affects economic activity indirectly. The most significant channel by which the effects of the shock are transmitted is the government's spending. (author)

  17. Delayed Failure in a Shock Loaded Alumina

    Cooper, G. A.; Millett, J. C. F.; Bourne, N. K.; Dandekar, D. P.

    2006-01-01

    Manganin stress gauges have been used to measure the lateral stress in a shock-loaded alumina. In combination with known longitudinal stresses, these have been used to determine the shear strength of this material, behind the shock front. The two-step nature of the lateral stress traces shows a slow moving front behind the main shock, behind which shear strength undergoes a significant decrease. Results also show that this front decreases markedly in velocity as the HEL is crossed, suggesting that limited plasticity occurs during inelastic deformation. Finally, comparison of measured shear strengths with other aluminas shows a high degree of agreement

  18. Turbulent energy generated by accelerations and shocks

    Mikaelian, K.O.

    1986-01-01

    The turbulent energy generated at the interface between two fluids undergoing a constant acceleration or a shock is calculated. Assuming linear density profiles in the mixed region we find E/sub turbulent//E/sub directed/ = 2.3A 2 % (constant acceleration) and 9.3A 2 % (shock), where A is the Atwood number. Diffusion models predict somewhat less turbulent energy and a density profile with a tail extending into the lower density fluid. Eddy sizes are approximately 27% (constant acceleration) and 17% (shock) of the mixing depth into the heavier fluid. 6 refs., 3 figs

  19. Underwater electrical wire explosion: Shock wave from melting being overtaken by shock wave from vaporization

    Li, Liuxia; Qian, Dun; Zou, Xiaobing; Wang, Xinxin

    2018-05-01

    The shock waves generated by an underwater electrical wire explosion were investigated. A microsecond time-scale pulsed current source was used to trigger the electrical explosion of copper wires with a length of 5 cm and a diameter of 200 μm. The energy-storage capacitor was charged to a relatively low energy so that the energy deposited onto the wire was not large enough to fully vaporize the whole wire. Two shock waves were recorded with a piezoelectric gauge that was located at a position of 100 mm from the exploding wire. The first and weak shock wave was confirmed to be the contribution from wire melting, while the second and stronger shock wave was the contribution from wire vaporization. The phenomenon whereby the first shock wave generated by melting being overtaken by the shock wave due to vaporization was observed.

  20. Multiple spacecraft observations of interplanetary shocks Four spacecraft determination of shock normals

    Russell, C. T.; Mellott, M. M.; Smith, E. J.; King, J. H.

    1983-01-01

    ISEE 1, 2, 3, IMP 8, and Prognoz 7 observations of interplanetary shocks in 1978 and 1979 provide five instances where a single shock is observed by four spacecraft. These observations are used to determine best-fit normals for these five shocks. In addition to providing well-documented shocks for future investigations these data allow the evaluation of the accuracy of several shock normal determination techniques. When the angle between upstream and downstream magnetic field is greater than 20 deg, magnetic coplanarity can be an accurate single spacecraft method. However, no technique based solely on the magnetic measurements at one or multiple sites was universally accurate. Thus, the use of overdetermined shock normal solutions, utilizing plasma measurements, separation vectors, and time delays together with magnetic constraints, is recommended whenever possible.

  1. Reliability assessment of competing risks with generalized mixed shock models

    Rafiee, Koosha; Feng, Qianmei; Coit, David W.

    2017-01-01

    This paper investigates reliability modeling for systems subject to dependent competing risks considering the impact from a new generalized mixed shock model. Two dependent competing risks are soft failure due to a degradation process, and hard failure due to random shocks. The shock process contains fatal shocks that can cause hard failure instantaneously, and nonfatal shocks that impact the system in three different ways: 1) damaging the unit by immediately increasing the degradation level, 2) speeding up the deterioration by accelerating the degradation rate, and 3) weakening the unit strength by reducing the hard failure threshold. While the first impact from nonfatal shocks comes from each individual shock, the other two impacts are realized when the condition for a new generalized mixed shock model is satisfied. Unlike most existing mixed shock models that consider a combination of two shock patterns, our new generalized mixed shock model includes three classic shock patterns. According to the proposed generalized mixed shock model, the degradation rate and the hard failure threshold can simultaneously shift multiple times, whenever the condition for one of these three shock patterns is satisfied. An example using micro-electro-mechanical systems devices illustrates the effectiveness of the proposed approach with sensitivity analysis. - Highlights: • A rich reliability model for systems subject to dependent failures is proposed. • The degradation rate and the hard failure threshold can shift simultaneously. • The shift is triggered by a new generalized mixed shock model. • The shift can occur multiple times under the generalized mixed shock model.

  2. Differential effect of ketamine and lidocaine on spontaneous and mechanical evoked pain in patients with nerve injury pain

    Gottrup, Hanne; Bach, Flemming Winther; Juhl, Gitte Irene

    2006-01-01

    ketamine, an N-methyl-D-aspartate receptor antagonist and lidocaine, a sodium channel blocker, on spontaneous pain, brush-evoked pain, and pinprick-evoked pain in patients with nerve injury pain. METHODS: Twenty patients participated in two randomized, double-blinded, placebo-controlled, crossover...... experiments in which they, on four different days, received a 30-minute intravenous infusion of ketamine (0.24 mg/kg), lidocaine (5 mg/kg), or saline. Ongoing pain, pain evoked by brush and repetitive pinprick stimuli, and acetone was measured before, during, and after infusion. RESULTS: Ketamine...... significantly reduced ongoing pain and evoked pain to brush and pinprick, whereas lidocaine only reduced evoked pain to repetitive pinprick stimuli. In individual patients, there was no correlation between the pain-relieving effect of lidocaine and ketamine on ongoing or mechanically evoked pains. CONCLUSIONS...

  3. Objective correlate of subjective pain perception by contact heat-evoked potentials.

    Granovsky, Yelena; Granot, Michal; Nir, Rony-Reuven; Yarnitsky, David

    2008-01-01

    The method of pain-evoked potentials has gained considerable acceptance over the last 3 decades regarding its objectivity, repeatability, and quantifiability. The present study explored whether the relationship between pain-evoked potentials and pain psychophysics obtained by contact heat stimuli is similar to those observed for the conventionally used laser stimulation. Evoked potentials (EPs) were recorded in response to contact heat stimuli at different body sites in 24 healthy volunteers. Stimuli at various temperatures were applied to the forearm (43 degrees C, 46 degrees C, 49 degrees C, and 52 degrees C) and leg (46 degrees C and 49 degrees C). The amplitudes of both components (N2 and P2) were strongly associated with the intensity of the applied stimuli and with subjective pain perception. Yet, regression analysis revealed pain perception and not stimulus intensity as the major contributing factor. A significant correlation was found between the forearm and the leg for both psychophysics and EPs amplitude. Contact heat can generate readily distinguishable evoked potentials on the scalp, consistent between upper and lower limbs. Although these potentials bear positive correlation with both stimulus intensity and pain magnitude, the latter is the main contributor to the evoked brain response.

  4. Speech-evoked auditory brainstem responses in children with hearing loss.

    Koravand, Amineh; Al Osman, Rida; Rivest, Véronique; Poulin, Catherine

    2017-08-01

    The main objective of the present study was to investigate subcortical auditory processing in children with sensorineural hearing loss. Auditory Brainstem Responses (ABRs) were recorded using click and speech/da/stimuli. Twenty-five children, aged 6-14 years old, participated in the study: 13 with normal hearing acuity and 12 with sensorineural hearing loss. No significant differences were observed for the click-evoked ABRs between normal hearing and hearing-impaired groups. For the speech-evoked ABRs, no significant differences were found for the latencies of the following responses between the two groups: onset (V and A), transition (C), one of the steady-state wave (F), and offset (O). However, the latency of the steady-state waves (D and E) was significantly longer for the hearing-impaired compared to the normal hearing group. Furthermore, the amplitude of the offset wave O and of the envelope frequency response (EFR) of the speech-evoked ABRs was significantly larger for the hearing-impaired compared to the normal hearing group. Results obtained from the speech-evoked ABRs suggest that children with a mild to moderately-severe sensorineural hearing loss have a specific pattern of subcortical auditory processing. Our results show differences for the speech-evoked ABRs in normal hearing children compared to hearing-impaired children. These results add to the body of the literature on how children with hearing loss process speech at the brainstem level. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. From Nose to Memory: The Involuntary Nature of Odor-evoked Autobiographical Memories in Alzheimer's Disease.

    El Haj, Mohamad; Gandolphe, Marie Charlotte; Gallouj, Karim; Kapogiannis, Dimitrios; Antoine, Pascal

    2017-12-25

    Research suggests that odors may serve as a potent cue for autobiographical retrieval. We tested this hypothesis in Alzheimer's disease (AD) and investigated whether odor-evoked autobiographical memory is an involuntary process that shares similarities with music-evoked autobiographical memory. Participants with mild AD and controls were asked to retrieve 2 personal memories after odor exposure, after music exposure, and in an odor-and music-free condition. AD participants showed better specificity, emotional experience, mental time travel, and retrieval time after odor and music exposure than in the control condition. Similar beneficial effects of odor and music exposure were observed for autobiographical characteristics (i.e., specificity, emotional experience, and mental time travel), except for retrieval time which was more improved after odor than after music exposure. Interestingly, regression analyses suggested executive involvement in memories evoked in the control condition but not in those evoked after music or odor exposure. These findings suggest the involuntary nature of odor-evoked autobiographical memory in AD. They also suggest that olfactory cuing could serve as a useful and ecologically valid tool to stimulate autobiographical memory, at least in the mild stage of the disease. © The Author(s) 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Behavioral analyses of wind-evoked escape of the cricket, Gryllodes sigillatus.

    Kanou, Masamichi; Konishi, Atsuko; Suenaga, Rie

    2006-04-01

    The wind-evoked escape behavior of the cricket Gryllodes sigillatus was investigated using an air puff stimulus. A high velocity air puff elicited the escape behavior in many crickets. The crickets tended to escape away from the stimulus source, but the direction was not accurately oriented 180 degrees from the stimulus. After bilateral cercal ablation, only a few crickets showed wind-evoked escape behavior, and their response rates did not increase even 19 days after ablation. Therefore, information on air motion detected by cercal filiform hairs is essential for triggering wind-evoked behavior. After unilateral cercal ablation, the 81.3% response rate of intact crickets decreased to 16.5%, that is, it decreased to almost 20% that of intact crickets. One week after unilateral cercal ablation, the response rate recovered to more than 60% that of intact crickets. However, the accuracy rate of the escape direction of G. sigillatus showed no change even immediately after the unilateral cercal ablation. Therefore, both cerci are not necessarily required to determine the escape direction. The behavioral characteristics of wind-evoked escape of G. sigillatus are compared with those of another species of cricket, Gryllus bimaculatus. The two species of cricket employ different strategies for wind-evoked escape.

  7. Dynamic properties of sensory stimulation evoked responses in mouse cerebellar granule cell layer and molecular layer.

    Bing, Yan-Hua; Zhang, Guang-Jian; Sun, Lei; Chu, Chun-Ping; Qiu, De-Lai

    2015-01-12

    Sensory information coming from climbing fiber and mossy fiber-granule cell pathways, generates motor-related outputs according to internal rules of integration and computation in the cerebellar cortex. However, the dynamic properties of sensory information processing in mouse cerebellar cortex are less understood. Here, we studied the dynamic properties of sensory stimulation-evoked responses in the cerebellar granule cell layer (GCL) and molecular layer (ML) by electrophysiological recordings method. Our data showed that air-puff stimulation (5-10 ms in duration) of the ipsilateral whisker pad evoked single-peak responses in the GCL and ML; whereas a duration of stimulation ≥30 ms in GCL and ≥60 ms in ML, evoked double-peak responses that corresponded with stimulation-on and -off responses via mossy fiber pathway. The highest frequency of stimulation train for evoking GCL responses was 33 Hz. In contrast, the highest frequency of stimulation train for evoking ML responses was 4 Hz. These results indicate that the cerebellar granule cells transfer the high-fidelity sensory information from mossy fibers, which is cut-off by molecular layer interneurons (MLIs). Our results suggest that the MLIs network acts as a low-pass filter during the processing of high-frequency sensory information. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  8. Phantom somatosensory evoked potentials following selective intraneural electrical stimulation in two amputees.

    Granata, Giuseppe; Di Iorio, Riccardo; Romanello, Roberto; Iodice, Francesco; Raspopovic, Stanisa; Petrini, Francesco; Strauss, Ivo; Valle, Giacomo; Stieglitz, Thomas; Čvančara, Paul; Andreu, David; Divoux, Jean-Louis; Guiraud, David; Wauters, Loic; Hiairrassary, Arthur; Jensen, Winnie; Micera, Silvestro; Rossini, Paolo Maria

    2018-06-01

    The aim of the paper is to objectively demonstrate that amputees implanted with intraneural interfaces are truly able to feel a sensation in the phantom hand by recording "phantom" somatosensory evoked potentials from the corresponding brain areas. We implanted four transverse intrafascicular multichannel electrodes, available with percutaneous connections to a multichannel electrical stimulator, in the median and ulnar nerves of two left trans-radial amputees. Two channels of the implants that were able to elicit sensations during intraneural nerve stimulation were chosen, in both patients, for recording somatosensory evoked potentials. We recorded reproducible evoked responses by stimulating the median and the ulnar nerves in both cases. Latencies were in accordance with the arrival of somatosensory information to the primary somatosensory cortex. Our results provide evidence that sensations generated by intraneural stimulation are truly perceived by amputees and located in the phantom hand. Moreover, our results strongly suggest that sensations perceived in different parts of the phantom hand result in different evoked responses. Somatosensory evoked potentials obtained by selective intraneural electrical stimulation in amputee patients are a useful tool to provide an objective demonstration of somatosensory feedback in new generation bidirectional prostheses. Copyright © 2018. Published by Elsevier B.V.

  9. Enhanced brainstem and cortical evoked response amplitudes: single-trial covariance analysis.

    Galbraith, G C

    2001-06-01

    The purpose of the present study was to develop analytic procedures that improve the definition of sensory evoked response components. Such procedures could benefit all recordings but would especially benefit difficult recordings where many trials are contaminated by muscle and movement artifacts. First, cross-correlation and latency adjustment analyses were applied to the human brainstem frequency-following response and cortical auditory evoked response recorded on the same trials. Lagged cross-correlation functions were computed, for each of 17 subjects, between single-trial data and templates consisting of the sinusoid stimulus waveform for the brainstem response and the subject's own smoothed averaged evoked response P2 component for the cortical response. Trials were considered in the analysis only if the maximum correlation-squared (r2) exceeded .5 (negatively correlated trials were thus included). Identical correlation coefficients may be based on signals with quite different amplitudes, but it is possible to assess amplitude by the nonnormalized covariance function. Next, an algorithm is applied in which each trial with negative covariance is matched to a trial with similar, but positive, covariance and these matched-trial pairs are deleted. When an evoked response signal is present in the data, the majority of trials positively correlate with the template. Thus, a residual of positively correlated trials remains after matched covariance trials are deleted. When these residual trials are averaged, the resulting brainstem and cortical responses show greatly enhanced amplitudes. This result supports the utility of this analysis technique in clarifying and assessing evoked response signals.

  10. Effects of single cycle binaural beat duration on auditory evoked potentials.

    Mihajloski, Todor; Bohorquez, Jorge; Özdamar, Özcan

    2014-01-01

    Binaural beat (BB) illusions are experienced as continuous central pulsations when two sounds with slightly different frequencies are delivered to each ear. It has been shown that steady-state auditory evoked potentials (AEPs) to BBs can be captured and investigated. The authors recently developed a new method of evoking transient AEPs to binaural beats using frequency modulated stimuli. This methodology was able to create single BBs in predetermined intervals with varying carrier frequencies. This study examines the effects of the BB duration and the frequency modulating component of the stimulus on the binaural beats and their evoked potentials. Normal hearing subjects were tested with a set of four durations (25, 50, 100, and 200 ms) with two stimulation configurations, binaural dichotic (binaural beats) and diotic (frequency modulation). The results obtained from the study showed that out of the given durations, the 100 ms beat, was capable of evoking the largest amplitude responses. The frequency modulation effect showed a decrease in peak amplitudes with increasing beat duration until their complete disappearance at 200 ms. Even though, at 200 ms, the frequency modulation effects were not present, the binaural beats were still perceived and captured as evoked potentials.

  11. Shock wave physics group (M-6)

    Morris, C.E.

    1981-01-01

    Experimental facilities and activities of the shock wave physics group at LASL are described. The facilities include a compressed gas gun, two-stage gas gun, high explosive facilities, and a pulsed megagauss field facility

  12. Integrated microelectromechanical gyroscope under shock loads

    Nesterenko, T. G.; Koleda, A. N.; Barbin, E. S.

    2018-01-01

    The paper presents a new design of a shock-proof two-axis microelectromechanical gyroscope. Without stoppers, the shock load enables the interaction between the silicon sensor elements. Stoppers were installed in the gyroscope to prevent the contact interaction between electrodes and spring elements with fixed part of the sensor. The contact of stoppers occurs along the plane, thereby preventing the system from serious contact stresses. The shock resistance of the gyroscope is improved by the increase in its eigenfrequency at which the contact interaction does not occur. It is shown that the shock load directed along one axis does not virtually cause the movement of sensing elements along the crosswise axes. Maximum stresses observed in the proposed gyroscope at any loading direction do not exceed the value allowable for silicon.

  13. Tribology Aspect of Rubber Shock Absorbers Development

    M. Banić

    2013-09-01

    Full Text Available Rubber is a very flexible material with many desirable properties Which enable its broad use in engineering practice. Rubber or rubber-metal springs are widely used as anti-vibration or anti-shock components in technical systems. Rubber-metal springs are usually realized as a bonded assembly, however especially in shock absorbers, it is possible to realize free contacts between rubber and metal parts. In previous research it authors was observed that friction between rubber and metal in such case have a significant influence on the damping characteristics of shock absorber. This paper analyzes the development process of rubber or rubber-metal shock absorbers realized free contacts between the constitutive parts, starting from the design, construction, testing and operation, with special emphasis on the development of rubber-metal springs for the buffing and draw gear of railway vehicles.

  14. Role of drifts in diffusive shock acceleration

    Decker, R.B.

    1988-01-01

    The role played by shock-associated drifts during the diffusive acceleration of charged particles at collisionless MHD shocks is evaluated. In the rest frame of the shock, the total energy gained by a particle is shown to result from two coupled acceleration mechanisms, the usual first-order Fermi mechanism and the drift mechanism. When averaged over a distribution of particles, the ratio of the drift-associated energy gain to the total energy is found to be independent of the total energy at a given theta1 (the angle between the shock normal and the unperturbed upstream magnetic field) in agreement with theoretical predictions. No evidence is found for drift-associated deceleration, suggesting that drifts always augment acceleration. 35 references

  15. Shock Thermodynamic Applied Research Facility (STAR)

    Federal Laboratory Consortium — The STAR facility, within Sandia's Solid Dynamic Physics Department, is one of a few institutions in the world with a major shock-physics program. This is the only...

  16. Nonequilibrium recombination after a curved shock wave

    Wen, Chihyung; Hornung, Hans

    2010-02-01

    The effect of nonequilibrium recombination after a curved two-dimensional shock wave in a hypervelocity dissociating flow of an inviscid Lighthill-Freeman gas is considered. An analytical solution is obtained with the effective shock values derived by Hornung (1976) [5] and the assumption that the flow is ‘quasi-frozen’ after a thin dissociating layer near the shock. The solution gives the expression of dissociation fraction as a function of temperature on a streamline. A rule of thumb can then be provided to check the validity of binary scaling for experimental conditions and a tool to determine the limiting streamline that delineates the validity zone of binary scaling. The effects on the nonequilibrium chemical reaction of the large difference in free stream temperature between free-piston shock tunnel and equivalent flight conditions are discussed. Numerical examples are presented and the results are compared with solutions obtained with two-dimensional Euler equations using the code of Candler (1988) [10].

  17. Critical point anomalies include expansion shock waves

    Nannan, N. R., E-mail: ryan.nannan@uvs.edu [Mechanical Engineering Discipline, Anton de Kom University of Suriname, Leysweg 86, PO Box 9212, Paramaribo, Suriname and Process and Energy Department, Delft University of Technology, Leeghwaterstraat 44, 2628 CA Delft (Netherlands); Guardone, A., E-mail: alberto.guardone@polimi.it [Department of Aerospace Science and Technology, Politecnico di Milano, Via La Masa 34, 20156 Milano (Italy); Colonna, P., E-mail: p.colonna@tudelft.nl [Propulsion and Power, Delft University of Technology, Kluyverweg 1, 2629 HS Delft (Netherlands)

    2014-02-15

    From first-principle fluid dynamics, complemented by a rigorous state equation accounting for critical anomalies, we discovered that expansion shock waves may occur in the vicinity of the liquid-vapor critical point in the two-phase region. Due to universality of near-critical thermodynamics, the result is valid for any common pure fluid in which molecular interactions are only short-range, namely, for so-called 3-dimensional Ising-like systems, and under the assumption of thermodynamic equilibrium. In addition to rarefaction shock waves, diverse non-classical effects are admissible, including composite compressive shock-fan-shock waves, due to the change of sign of the fundamental derivative of gasdynamics.

  18. Shock Wave Science and Technology Reference Library

    2007-01-01

    Shock waves in multiphase flows refers to a rich variety of phenomena of interest to physicists, chemists, and fluid dynamicists, as well as mechanical, biomedical and aeronautical engineers. This volume treats shock and expansion waves in (bullet) complex, bubbly liquids (L van Wijngaarden, Y Tomita, V Kedrinskii) and (bullet) cryogenic liquids (M Murakami) and examines the relationship of shock waves with (bullet) phase transitions (A Guha, CF Delale, G Schnerr, MEH van Dongen) (bullet) induced phase transitions (GEA Meier) as well as their interaction with (bullet) solid foams, textiles, porous and granular media (B Skews, DMJ Smeulders, MEH van Dongen, V Golub, O Mirova) All chapters are self-contained, so they can be read independently, although they are of course thematically interrelated. Taken together, they offer a timely reference on shock waves in multiphase flows, including new viewpoints and burgeoning developments. The book will appeal to beginners as well as professional scientists and engineer...

  19. Comments on ''Analysis of spherical imploding shocks''

    Lazarus, R.B.

    1980-01-01

    It is asserted that Fujimoto and Mishkin's article is incorrect in its claim for a pressure extremum at or behind the shock for all values of γ and in its claim for an analytical form for the similarity exponent

  20. Shock-induced modification of inorganic powders

    Graham, R.A.; Morosin, B.; Venturini, E.L.; Beauchamp, E.K.; Hammetter, W.F.

    1984-01-01

    The results of studies performed to quantify the characteristics of TiO2, ZrO2 and Si3N4 powders exposed to explosive loading and post-shock analysis are reported. The shocks were produced with plane wave generators and explosive pads impinging on steel disks, a copper recovery fixture, and then the samples. Peak pressures of 13 and 17 GPa were attained, along with 40 GPz at the center of the powder cavity. Data are provided on the changes occurring during the explosive densification and X-ray and paramagnetic studies of the products. Only fractured disks were obtained in the trials. The shock-treated materials were more free flowing than the original powders, which were fluffy. Post-shock annealing was a significant feature of the treated powders

  1. SPECIAL PURPOSE SHOCK TUBE for BLAST ASSESSMENT

    Federal Laboratory Consortium — This device is a specially designed shock tube for testing fabric samples in a controlled environment. The device determines the appropriate types of sensors to be...

  2. Collisions on relativistic nuclei: shock waves

    Gudima, K.K.; Toneev, V.D.

    1976-01-01

    Experiments are analysed which indicate the possible generation of shock waves in collisions of two nuclei. Another interpretation of these data is proposed and the concerned new experiments are discussed

  3. Analysis of Z Pinch Shock Wave Experiments

    Asay, James; Budge, Kent G.; Chandler, Gordon; Fleming, Kevin; Hall, Clint; Holland, Kathleen; Konrad, Carl; Lawrence, Jeffery; Trott, Wayne; Trucano, Timothy

    1999-01-01

    In this paper, we report details of our computational study of two shock wave physics experiments performed on the Sandia Z machine in 1998. The novelty of these particular experiments is that they represent the first successful application of VISAR interferometry to diagnose shock waves generated in experimental payloads by the primary X-ray pulse of the machine. We use the Sandia shock-wave physics code ALEGRA to perform the simulations reported in this study. Our simulations are found to be in fair agreement with the time-resolved VISAR experimental data. However, there are also interesting and important discrepancies. We speculate as to future use of time-resolved shock wave data to diagnose details of the Z machine X-ray pulse in the future

  4. Shock Tube Measurements for Liquid Fuels Combustion

    Hanson, Ronald K

    2006-01-01

    ...) fundamental studies of fuel spray evaporation rates and ignition times of low-vapor pressure fuels such as JP-8, diesel fuel and normal alkane surrogates in a new aerosol shock tube using state...

  5. Condensed matter at high shock pressures

    Nellis, W.J.; Holmes, N.C.; Mitchell, A.C.; Radousky, H.B.; Hamilton, D.

    1985-07-12

    Experimental techniques are described for shock waves in liquids: Hugoniot equation-of-state, shock temperature and emission spectroscopy, electrical conductivity, and Raman spectroscopy. Experimental data are reviewed and presented in terms of phenomena that occur at high densities and temperatures in shocked He, Ar, N/sub 2/, CO, SiO/sub 2/-aerogel, H/sub 2/O, and C/sub 6/H/sub 6/. The superconducting properties of Nb metal shocked to 100 GPa (1 Mbar) and recovered intact are discussed in terms of prospects for synthesizing novel, metastable materials. Ultrahigh pressure data for Cu is reviewed in the range 0.3 to 6TPa (3 to 60 Mbar). 56 refs., 9 figs., 1 tab.

  6. Shock wave science and technology reference library

    2009-01-01

    This book, as a volume of the Shock Wave Science and Technology Reference Library, is primarily concerned with detonation waves or compression shock waves in reactive heterogeneous media, including mixtures of solid, liquid and gas phases. The topics involve a variety of energy release and control processes in such media - a contemporary research field that has found wide applications in propulsion and power, hazard prevention as well as military engineering. The six extensive chapters contained in this volume are: - Spray Detonation (SB Murray and PA Thibault) - Detonation of Gas-Particle Flow (F Zhang) - Slurry Detonation (DL Frost and F Zhang) - Detonation of Metalized Composite Explosives (MF Gogulya and MA Brazhnikov) - Shock-Induced Solid-Solid Reactions and Detonations (YA Gordopolov, SS Batsanov, and VS Trofimov) - Shock Ignition of Particles (SM Frolov and AV Fedorov) Each chapter is self-contained and can be read independently of the others, though, they are thematically interrelated. They offer a t...

  7. Comparative review of bow shocks and magnetopauses

    Lepping, R.P.

    1984-04-01

    Bow shock and magnetopauses formation is discussed. Plasma and magnetic field environments of all the planets from Mercury to Saturn were measured. It was found that all the planets have bow shocks and almost all have a magnetopause. Venus is the only planet with no measurable intrinsic magnetic field and the solar wind interacts directly with Venus ionosphere. The bow shock characteristics depend on the changing solar wind conditions. The shape of a magnetopause or any obstacle to flow depends on the three dimensional pressure profile that it presents to the solar wind. Jupiter is unusual because of the considerable amount of plasma which is contained in its magnetosphere. Magentopause boundaries in ecliptic plane projection are modelled by segments of ellipses, matched to straight lines for the magnetotool boundaries or parabolas. Specific properties of known planetary bow shocks and magnetopauses are reviewed

  8. Medical and biomedical applications of shock waves

    Loske, Achim M

    2017-01-01

    This book provides current, comprehensive, and clear explanations of the physics behind medical and biomedical applications of shock waves. Extracorporeal shock wave lithotripsy is one of the greatest medical advances of our time, and its techniques and clinical devices are continuously evolving. Further research continues to improve the understanding of calculi fragmentation and tissue-damaging mechanisms. Shock waves are also used in orthopedics and traumatology. Possible applications in oncology, cardiology, dentistry, gene therapy, cell transfection, transformation of fungi and bacteria, as well as the inactivation of microorganisms are promising approaches for clinical treatment, industrial applications and research. Medical and Biomedical Applications of Shock Waves is useful as a guide for students, technicians and researchers working in universities and laboratories. Chemists, biologists, physicians and veterinarians, involved in research or clinical practice will find useful advice, but also engineer...

  9. Relative locations of the bow shocks of the terrestrial planets

    Russell, C.T.

    1977-01-01

    The observed bow shock encounters at Mercury, Venus and Mars are least square fit using the same technique so that their sizes and shapes can be intercompared. The shock front of Mercury most resembles the terrestrial shock in shape, and the shock stand off distance is consistent with the observed moment. The shapes of the Venus and Mars shock fronts more resemble each other than the earth's and the stand off distances are consistent with direct interaction of the solar wind with the ionosphere on the dayside. The Venus shock is closer to the planet than the Mars shock suggesting more absorption of the solar wind at Venus

  10. Orientation Dependence in Molecular Dynamics Simulations of Shocked Single Crystals

    Germann, Timothy C.; Holian, Brad Lee; Lomdahl, Peter S.; Ravelo, Ramon

    2000-01-01

    We use multimillion-atom molecular dynamics simulations to study shock wave propagation in fcc crystals. As shown recently, shock waves along the direction form intersecting stacking faults by slippage along {111} close-packed planes at sufficiently high shock strengths. We find even more interesting behavior of shocks propagating in other low-index directions: for the case, an elastic precursor separates the shock front from the slipped (plastic) region. Shock waves along the direction generate a leading solitary wave train, followed (at sufficiently high shock speeds) by an elastic precursor, and then a region of complex plastic deformation. (c) 2000 The American Physical Society

  11. The stress protein heat shock cognate 70 (Hsc70) inhibits the Transient Receptor Potential Vanilloid type 1 (TRPV1) channel.

    Iftinca, Mircea; Flynn, Robyn; Basso, Lilian; Melo, Helvira; Aboushousha, Reem; Taylor, Lauren; Altier, Christophe

    2016-01-01

    Specialized cellular defense mechanisms prevent damage from chemical, biological, and physical hazards. The heat shock proteins have been recognized as key chaperones that maintain cell survival against a variety of exogenous and endogenous stress signals including noxious temperature. However, the role of heat shock proteins in nociception remains poorly understood. We carried out an expression analysis of the constitutively expressed 70 kDa heat-shock cognate protein, a member of the stress-induced HSP70 family in lumbar dorsal root ganglia from a mouse model of Complete Freund's Adjuvant-induced chronic inflammatory pain. We used immunolabeling of dorsal root ganglion neurons, behavioral analysis and patch clamp electrophysiology in both dorsal root ganglion neurons and HEK cells transfected with Hsc70 and Transient Receptor Potential Channels to examine their functional interaction in heat shock stress condition. We report an increase in protein levels of Hsc70 in mouse dorsal root ganglia, 3 days post Complete Freund's Adjuvant injection in the hind paw. Immunostaining of Hsc70 was observed in most of the dorsal root ganglion neurons, including the small size nociceptors immunoreactive to the TRPV1 channel. Standard whole-cell patch-clamp technique was used to record Transient Receptor Potential Vanilloid type 1 current after exposure to heat shock. We found that capsaicin-evoked currents are inhibited by heat shock in dorsal root ganglion neurons and transfected HEK cells expressing Hsc70 and TRPV1. Blocking Hsc70 with matrine or spergualin compounds prevented heat shock-induced inhibition of the channel. We also found that, in contrast to TRPV1, both the cold sensor channels TRPA1 and TRPM8 were unresponsive to heat shock stress. Finally, we show that inhibition of TRPV1 depends on the ATPase activity of Hsc70 and involves the rho-associated protein kinase. Our work identified Hsc70 and its ATPase activity as a central cofactor of TRPV1 channel function

  12. THE EFFECTS OF AREA CONTRACTION ON SHOCK WAVE STRENGTH AND PEAK PRESSURE IN SHOCK TUBE

    A. M. Mohsen

    2012-06-01

    Full Text Available This paper presents an experimental investigation into the effects of area contraction on shock wave strength and peak pressure in a shock tube. The shock tube is an important component of the short duration, high speed fluid flow test facility, available at the Universiti Tenaga Nasional (UNITEN, Malaysia. The area contraction was facilitated by positioning a bush adjacent to the primary diaphragm section, which separates the driver and driven sections. Experimental measurements were performed with and without the presence of the bush, at various diaphragm pressure ratios, which is the ratio of air pressure between the driver (high pressure and driven (low pressure sections. The instantaneous static pressure variations were measured at two locations close to the driven tube end wall, using high sensitivity pressure sensors, which allow the shock wave strength, shock wave speed and peak pressure to be analysed. The results reveal that the area contraction significantly reduces the shock wave strength, shock wave speed and peak pressure. At a diaphragm pressure ratio of 10, the shock wave strength decreases by 18%, the peak pressure decreases by 30% and the shock wave speed decreases by 8%.

  13. Waves and Instabilities in Collisionless Shocks

    1984-04-01

    occur in the electron foreshock and are driven by suprathermal electrons escaping into the region upstream of the shock. Both the ion-acoustic and...ULF waves occur in the ion foreshock and are associated with ions streaming into the region upstream of 11 the shock. The region downstream of the...the discussion of these waves it is useful to distinguish two regions, called the electron foreshock and the ion foreshock . Because the particles

  14. The Dynamic Quasiperpendicular Shock: Cluster Discoveries

    Krasnoselskikh, V.; Balikhin, M.; Walker, S. N.; Schwartz, S.; Sundkvist, D.; Lobzin, V.; Gedalin, M.; Bale, S. D.; Mozer, F.; Souček, Jan; Hobara, Y.; Comisel, H.

    2013-01-01

    Roč. 178, 2-4 (2013), s. 535-598 ISSN 0038-6308 Institutional support: RVO:68378289 Keywords : collisionless shocks * waves in plasmas * nonstationarity * shock scales * plasma heating and acceleration * wave-particle interactions Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 5.874, year: 2013 http://link.springer.com/article/10.1007%2Fs11214-013-9972-y

  15. Flow control for oblique shock wave reflections

    Giepman, R.H.M.

    2016-01-01

    Shock wave-boundary layer interactions are prevalent in many aerospace applications that involve transonic or supersonic flows. Such interactions may lead to boundary layer separation, flow unsteadiness and substantial losses in the total pressure. Flow control techniques can help to mitigate these adverse effects and stabilize the interaction. This thesis focuses on passive flow control techniques for oblique shock wave reflections on flat plates and presents experimental results for both la...

  16. Public Investment, Revenue Shocks, and Borrowing Restrictions

    Büttner, Thiess; Wildasin, David E.

    2010-01-01

    This paper lays out a theory of taxation and public investment in an intertemporal setting under conditions of revenue shocks. Without borrowing restrictions, the optimal policy is characterized by smooth time paths of taxes and public investment. While the introduction of formal borrowing restrictions leads to some precautionary savings, it gives rise to fluctuations in public investment in response to adverse but also favorable revenue shocks. This theoretical result is tested empirically u...

  17. Optical Probes for Laser Induced Shocks

    1992-03-01

    target by the strong water. As the shock passes the material interface, it is pressure transients. only partially transmitted. The shock pressure is...T. Swimm , J. Appl. Phys. 61, evaporated, t1137(1987). vapor flow substantially. The coupling coefficient thus de- 3 v. A. Batanov and V. B. Fedorov...Waist-Surface Distance [mm] isurface on the drilling mechanismC Positive ( negative ) To roughly estimate the total recoil momentum positions

  18. Fast Electrocardiogram Amplifier Recovery after Defibrillation Shock

    Ivan Dotsinsky

    2005-04-01

    Full Text Available A procedure for fast ECG amplifier recovery after defibrillation shocks was developed and simulated in the MATLAB environment. Exponentially decaying post-shock voltages have been recorded. Signals from the AHA database are taken and mixed with the recorded exponential disturbances. The algorithm applies moving averaging (comb filter on the compound input signal, thereby obtaining the samples of the disturbance. They are currently subtracted from the input signal. The results obtained show that its recovery is practically instantaneous.

  19. Pressurized-thermal-shock experiments

    Whitman, G.D.; McCulloch, R.W.

    1982-01-01

    The primary objective of the ORNL pressurized-thermal-shock (PTS) experiments is to verify analytical methods that are used to predict the behavior of pressurized-water-reactor vessels under these accident conditions involving combined pressure and thermal loading. The criteria on which the experiments are based are: scale large enough to attain effective flaw border triaxial restraint and a temperature range sufficiently broad to produce a progression from frangible to ductile behavior through the wall at a given time; use of materials that can be completely characterized for analysis; stress states comparable to the actual vessel in zones of potential flaw extension; range of behavior to include cleavage initiation and arrest, cleavage initiation and arrest on the upper shelf, arrest in a high K/sub I/ gradient, warm prestressing, and entirely ductile behavior; long and short flaws with and without stainless steel cladding; and control of loads to prevent vessel burst, except as desired. A PTS test facility is under construction which will enable the establishment and control of wall temperature, cooling rate, and pressure on an intermediate test vessel (ITV) in order to simulate stress states representative of an actual reactor pressure vessel

  20. A FOCUSED TRANSPORT APPROACH TO THE TIME-DEPENDENT SHOCK ACCELERATION OF SOLAR ENERGETIC PARTICLES AT A FAST TRAVELING SHOCK

    Le Roux, J. A.; Webb, G. M.

    2012-01-01

    Some of the most sophisticated models for solar energetic particle (SEP) acceleration at coronal mass ejection driven shocks are based on standard diffusive shock acceleration theory. However, this theory, which only applies when SEP pitch-angle anisotropies are small, might have difficulty in describing first-order Fermi acceleration or the shock pre-heating and injection of SEPs into first-order Fermi acceleration accurately at lower SEP speeds where SEP pitch-angle anisotropies upstream near the shock can be large. To avoid this problem, we use a time-dependent focused transport model to reinvestigate first-order Fermi acceleration at planar parallel and quasi-parallel spherical traveling shocks between the Sun and Earth with high shock speeds associated with rare extreme gradual SEP events. The focused transport model is also used to investigate and compare three different shock pre-heating mechanisms associated with different aspects of the nonuniform cross-shock solar wind flow, namely, the convergence of the flow (adiabatic compression), the shear tensor of the flow, and the acceleration of the flow, and a fourth shock pre-heating mechanism associated with the cross-shock electric field, to determine which pre-heating mechanism contributes the most to injecting shock pre-heated source particles into the first-order Fermi acceleration process. The effects of variations in traveling shock conditions, such as increasing shock obliquity and shock slowdown, and variations in the SEP source with increasing shock distance from the Sun on the coupled processes of shock pre-heating, injection, and first-order Fermi acceleration are analyzed. Besides the finding that the cross-shock acceleration of the solar wind flow yields the dominant shock pre-heating mechanism at high shock speeds, we find that first-order Fermi acceleration at fast traveling shocks differs in a number of respects from the predictions and assumptions of standard steady-state diffusive shock

  1. Thermal shock investigation of silicon nitride

    Ziegler, G.; Leucht, R.

    1977-01-01

    In this work, the thermal shock properties of commercial reaction-bonded Si 3 N 4 quality material (RBSN), of commercial hot-pressed Si 3 N 4 (HPSN) and of different laboratory grades of hot-pressed Si 3 N 4 were examined. The thermal shock properties of RBSN quality material differ according to the structure considerably: The critical temperature difference for sample crossections of 5 x 5 or 6 x 6 mm after quenching in oil lies between 730 0 C and over 1400 0 C. The best thermal shock properties are shown by high density RBSN quality material having very fine pores and high initial strength. The results indicate that for RBSN large pores and density inhomogenities are responsible for bad thermal shock properties. Resistance to fast temperature change is higher for hot-pressed Si 3 N 4 than for RBSN quality material. In HPSN, the thermal shock results show dependence on structure. High MgO content and the associated coarse rod-shaped configuration of the β phase and structural inhomogenities affect the thermal shock properties in an adverse way. (orig.) [de

  2. Mechanical Properties of Shock-Damaged Rocks

    He, Hongliang; Ahrens, T. J.

    1994-01-01

    Stress-strain tests were performed both on shock-damaged gabbro and limestone. The effective Young's modulus decreases with increasing initial damage parameter value, and an apparent work-softening process occurs prior to failure. To further characterize shock-induced microcracks, the longitudinal elastic wave velocity behavior of shock-damaged gabbro in the direction of compression up to failure was measured using an acoustic transmission technique under uniaxial loading. A dramatic increase in velocity was observed for the static compressive stress range of 0-50 MPa. Above that stress range, the velocity behavior of lightly damaged (D(sub 0) less than 0.1) gabbro is almost equal to unshocked gabbro. The failure strength of heavily-damaged (D(sub 0) greater than 0.1) gabbro is approx. 100-150 MPa, much lower than that of lightly damaged and unshocked gabbros (approx. 230-260 MPa). Following Nur's theory, the crack shape distribution was analyzed. The shock-induced cracks in gabbro appear to be largely thin penny-shaped cracks with c/a values below 5 x 10(exp -4). Moreover, the applicability of Ashby and Sammis's theory relating failure strength and damage parameter of shock-damaged rocks was examined and was found to yield a good estimate of the relation of shock-induced deficit in elastic modulus with the deficit in compressive strength.

  3. Emissive spectra of shock-heated argon

    Tang Jingyou; Gu Yan; Peng Qixian; Bai Yulin; Li Ping

    2003-01-01

    To study the radiant properties of argon under weak shock compression, an aluminum target filled with gaseous argon at ambient states was impacted by a tungsten alloy projectile which was launched from a two-stage light gun to 2.00 km/s. The radiant signals of single shock-compressed argon were recorded by a six-channel pyrometer and oscilloscopes, which varied with time linearly for the five channels from 405 nm to 700 nm and exponentially for the channel 800 nm, and the corresponding velocity of shock wave was determined to be 4.10 ± 0.09 km/s. By the present experiment, it has been shown that the absorbability of the shock-heated argon is low for visual light and the optical depths of argon gas turn from thin to thick as wavelengths gradually increase. The time-resolved spectra in the rising-front of the radiant signal in the re-shocked argon were recorded by means of an OMA, and strong emissive spectrum bands near 450 nm light-wave length but no linear spectrum were found. The emissive spectrum properties of shock-compression argon were qualitatively explained by the state parameters and ionization degree

  4. Pick-up ion energization at the termination shock

    Gary, S Peter [Los Alamos National Laboratory; Winske, Dan [Los Alamos National Laboratory; Wu, Pin [BOSTON UNIV.; Schwadron, N A [BOSTON UNIV.

    2009-01-01

    One-dimensional hybrid simulations are used to investigate how pickup ions are energized at the perpendicular termination shock. Contrary to previous models based on pickup ion energy gain by repeated crossings of the shock front (shock surfing) or due to a reforming shock front, the present simulations show that pickup ion energy gain involves a gyro-phasedependent interaction with the inhomogeneous motional electric field at the shock. The process operates at all relative concentrations of pickup ion density.

  5. Phasing out nuclear: shock statements by the EDF's CEO

    Benezet, E.; Mouchon, F.; Lomazzi, M.; Jeanne, M.

    2011-01-01

    While costs associated with phasing out nuclear or cancelling of nuclear programs are briefly evoked for different European countries (Belgium, Germany, Italy), the EDF Chairman, Mr Proglio, comments the decisions of these countries, outlines the various risks associated with such a decision in France (job losses, greenhouse gas emissions), also outlines EDF involvement in nuclear safety and evokes the issues of Fessenheim and of the EPR. Some French political aspects on that matter are also evoked

  6. Occipital lobe lesions result in a displacement of magnetoencephalography visual evoked field dipoles.

    Pang, Elizabeth W; Chu, Bill H W; Otsubo, Hiroshi

    2014-10-01

    The pattern-reversal visual evoked potential measured electrically from scalp electrodes is known to be decreased, or absent, in patients with occipital lobe lesions. We questioned whether the measurement and source analysis of the neuromagnetic visual evoked field (VEF) might offer additional information regarding visual cortex relative to the occipital lesion. We retrospectively examined 12 children (6-18 years) with occipital lesions on MRI, who underwent magnetoencephalography and ophthalmology as part of their presurgical assessment. Binocular half-field pattern-reversal VEFs were obtained in a 151-channel whole-head magnetoencephalography. Data were averaged and dipole source analyses were performed for each half-field stimulation. A significant lateral shift (P occipital lesions. Magnetoencephalography may be useful as a screening test of visual function in young patients. We discuss potential explanations for this lateral shift and emphasize the utility of adding the magnetoencephalography pattern-reversal visual evoked field protocol to the neurologic work-up.

  7. Effect of mechanical tactile noise on amplitude of visual evoked potentials: multisensory stochastic resonance.

    Méndez-Balbuena, Ignacio; Huidobro, Nayeli; Silva, Mayte; Flores, Amira; Trenado, Carlos; Quintanar, Luis; Arias-Carrión, Oscar; Kristeva, Rumyana; Manjarrez, Elias

    2015-10-01

    The present investigation documents the electrophysiological occurrence of multisensory stochastic resonance in the human visual pathway elicited by tactile noise. We define multisensory stochastic resonance of brain evoked potentials as the phenomenon in which an intermediate level of input noise of one sensory modality enhances the brain evoked response of another sensory modality. Here we examined this phenomenon in visual evoked potentials (VEPs) modulated by the addition of tactile noise. Specifically, we examined whether a particular level of mechanical Gaussian noise applied to the index finger can improve the amplitude of the VEP. We compared the amplitude of the positive P100 VEP component between zero noise (ZN), optimal noise (ON), and high mechanical noise (HN). The data disclosed an inverted U-like graph for all the subjects, thus demonstrating the occurrence of a multisensory stochastic resonance in the P100 VEP. Copyright © 2015 the American Physiological Society.

  8. Direct electrical stimulation of human cortex evokes high gamma activity that predicts conscious somatosensory perception

    Muller, Leah; Rolston, John D.; Fox, Neal P.; Knowlton, Robert; Rao, Vikram R.; Chang, Edward F.

    2018-04-01

    Objective. Direct electrical stimulation (DES) is a clinical gold standard for human brain mapping and readily evokes conscious percepts, yet the neurophysiological changes underlying these percepts are not well understood. Approach. To determine the neural correlates of DES, we stimulated the somatosensory cortex of ten human participants at frequency-amplitude combinations that both elicited and failed to elicit conscious percepts, meanwhile recording neural activity directly surrounding the stimulation site. We then compared the neural activity of perceived trials to that of non-perceived trials. Main results. We found that stimulation evokes distributed high gamma activity, which correlates with conscious perception better than stimulation parameters themselves. Significance. Our findings suggest that high gamma activity is a reliable biomarker for perception evoked by both natural and electrical stimuli.

  9. Controlling a stream of paranoia evoking events in a virtual reality environment.

    Isnanda, Reza Giga; Brinkman, Willem-Paul; Veling, Wim; van der Gaag, Mark; Neerincx, Mark

    2014-01-01

    Although virtual reality exposure has been reported as a method to induce paranoid thought, little is known about mechanisms to control specific virtual stressors. This paper reports on a study that examines the effect of controlling the stream of potential paranoia evoking events in a virtual restaurant world. A 2-by-2 experiment with a non-clinical group (n = 24) was conducted with as two within-subject factors: (1) the cycle time (short/long) for when the computer considers activation of a paranoia evoking event and (2) the probability that a paranoia-evoking event (low/high) would be triggered at the completion of a cycle. The results showed a significant main effect for the probability factor and two-way interaction effect with the cycle time factor on the number of paranoid comments participants made and their self-reported anxiety.

  10. Macroeconomic impacts of oil price shocks in Asian economies

    Cunado, Juncal; Jo, Soojin; Perez de Gracia, Fernando

    2015-01-01

    This paper analyzes the macroeconomic impact of structural oil shocks in four of the top oil-consuming Asian economies, using a VAR model. We identify three different structural oil shocks via sign restrictions: an oil supply shock, an oil demand shock driven by global economic activity and an oil-specific demand shock. The main results suggest that economic activity and prices respond very differently to oil price shocks depending on their types. In particular, an oil supply shock has a limited impact, while a demand shock driven by global economic activity has a significant positive effect in all four Asian countries examined. Our finding also includes that policy tools such as interest rates and exchange rates help mitigating the effects of supply shocks in Japan and Korea; however, they can be more actively used in response to demands shocks. - Highlights: • We analyze the effects of three structural oil price shocks on Asian economies. • Supply shocks have limited impact on the economic activity of Asian economies examined. • Demand shocks due to economic activity boosts GDP of all economies. • CPIs in India and Indonesia were only marginally affected by oil price shocks. • Monetary and exchange rate tools help mitigating supply shocks in Korea and Japan.

  11. Shock-wave induced mechanoluminescence: A new technique for studying effects of shock pressure on crystals

    Chandra, B.P.; Parganiha, S.; Sonwane, V.D. [School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur 492010, Chhattisgarh (India); Chandra, V.K. [Department of Electrical and Electronics Engineering, Chhatrapati Shivaji Institute of Technology, Shivaji Nagar, Kolihapuri, Durg 491001, Chhattisgarh (India); Jha, Piyush, E-mail: piyushjha22@rediffmail.com [Department of Applied Physics, Raipur Institute of Technology, Chhatauna, Mandir Hasuad, Raipur 492101, Chhattisgarh (India); Baghel, R.N. [School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur 492010, Chhattisgarh (India)

    2016-10-15

    The impact of a projectile propelled to velocities in the range of 0.5–2.5 km/s on to a target (X-cut quartz crystal) produces shock waves travelling at velocity of nearly 10 km/s in target, in which intense mechanoluminescence (ML) pulses of microsecond duration are produced, both in compression and post-compression conditions. The piezoelectric field produced due to surface charges of fractured target, causes band bending and subsequently, the free charge carriers are generated in the respective bands and the emission of ML occurs. The ML appears after a delay time t{sub th} whose value decreases with increasing value of the shock pressure. Initially, the ML intensity increases with the shock pressure because of the creation of more surfaces; however, for higher values of the shock pressure, the ML intensity tends to attain a saturation value because of the hardening of the crystals due to the creation of small crystallites in which the creation of new surfaces becomes difficult. The ratio between peak ML intensity in the uncompressed region and the maximum ML intensity in the compressed region decreases with increasing shock pressure because more defects produced at high pressure generate higher barrier for the relaxation of blocked cracks under compression. The expressions derived for characteristics of shock-induced ML are able to explain satisfactorily the experimental results. Shock-wave velocity, shock pressure, transit time, lifetime of electrons in conduction band, etc. can be determined by the shock-induced ML.As such, the shock-induced ML provides a new optical technique for the studies of materials under shock pressure.

  12. Refractory episodic vertigo: role of intratympanic gentamicin and vestibular evoked myogenic potentials.

    Celis-Aguilar, Erika; Hinojosa-González, Ramon; Vales-Hidalgo, Olivia; Coutinho-Toledo, Heloisa

    Even today, the treatment of intractable vertigo remains a challenge. Vestibular ablation with intratympanic gentamicin stands as a good alternative in the management of refractory vertigo patients. To control intractable vertigo through complete saccular and horizontal canal vestibular ablation with intratympanic gentamicin treatment. Patients with refractory episodic vertigo were included. The inclusion criteria were: unilateral ear disease, moderate to profound sensorineural hearing loss, and failure to other treatments. Included patients underwent 0.5-0.8mL of gentamicin intratympanic application at a 30mg/mL concentration. Vestibular ablation was confirmed by the absence of response on cervical vestibular evoked myogenic potentials and no response on caloric tests. Audiometry, electronystagmography with iced water, and vestibular evoked myogenic potentials were performed in all patients. Ten patients were included; nine patients with Meniere's disease and one patient with (late onset) delayed hydrops. Nine patients showed an absent response on vestibular evoked myogenic potentials and no response on caloric tests. The only patient with low amplitude on cervical vestibular evoked myogenic potentials had vertigo recurrence. Vertigo control was achieved in 90% of the patients. One patient developed hearing loss >30dB. Cervical vestibular evoked myogenic potentials confirmed vestibular ablation in patients treated with intratympanic gentamicin. High-grade vertigo control was due to complete saccular and horizontal canal ablation (no response to iced water in electronystagmography and no response on cervical vestibular evoked myogenic potentials). Copyright © 2016 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  13. A Reverse Shock in GRB 160509A

    Laskar, Tanmoy; Alexander, Kate D.; Berger, Edo; Fong, Wen-fai; Margutti, Raffaella; Shivvers, Isaac; Williams, Peter K. G.; Kopač, Drejc; Kobayashi, Shiho; Mundell, Carole; Gomboc, Andreja; Zheng, WeiKang; Menten, Karl M.; Graham, Melissa L.; Filippenko, Alexei V.

    2016-12-01

    We present the second multi-frequency radio detection of a reverse shock in a γ-ray burst. By combining our extensive radio observations of the Fermi-Large Area Telescope γ-ray burst 160509A at z = 1.17 up to 20 days after the burst with Swift X-ray observations and ground-based optical and near-infrared data, we show that the afterglow emission comprises distinct reverse shock and forward shock contributions: the reverse shock emission dominates in the radio band at ≲10 days, while the forward shock emission dominates in the X-ray, optical, and near-infrared bands. Through multi-wavelength modeling, we determine a circumburst density of {n}0≈ {10}-3 {{cm}}-3, supporting our previous suggestion that a low-density circumburst environment is conducive to the production of long-lasting reverse shock radiation in the radio band. We infer the presence of a large excess X-ray absorption column, N H ≈ 1.5 × 1022 {{cm}}-2, and a high rest-frame optical extinction, A V ≈ 3.4 mag. We identify a jet break in the X-ray light curve at {t}{jet}≈ 6 {days}, and thus derive a jet opening angle of {θ }{jet}≈ 4^\\circ , yielding a beaming-corrected kinetic energy and radiated γ-ray energy of {E}{{K}}≈ 4× {10}50 erg and {E}γ ≈ 1.3× {10}51 erg (1-104 keV, rest frame), respectively. Consistency arguments connecting the forward shocks and reverse shocks suggest a deceleration time of {t}{dec} ≈ 460 s ≈ T 90, a Lorentz factor of {{Γ }}({t}{dec})≈ 330, and a reverse-shock-to-forward-shock fractional magnetic energy density ratio of {R}{{B}}\\equiv {ɛ }{{B},{RS}}/{ɛ }{{B},{FS}}≈ 8. Our study highlights the power of rapid-response radio observations in the study of the properties and dynamics of γ-ray burst ejecta.

  14. Multimodal evoked potentials follow up in multiple sclerosis patients under fingolimod therapy

    Iodice, R; Carotenuto, A; Dubbioso, R

    2016-01-01

    related to EDSS at baseline (t=-1), while MEP and total EP sum score were related to EDSS at all time points. CONCLUSION: Fingolimod is able to improve visual and somatosensory evoked potential in RR-MS patients even if clinical disability scale remains stable. VEP and SEP could give eloquent information...... patients examined 12months prior to initiation of fingolimod (t=-1), at treatment initiation (t=0) and 1year later (t=+1) were compared. Each EP (VEP, MEP, SEP) and EP sum score, a global evoked potential score as the sum score of the each EP score was evaluated and correlated with Expanded Disability...

  15. Influence of detomidine and buprenorphine on motor-evoked potentials in horses.

    Nollet, H; Van Ham, L; Gasthuys, F; Dewulf, J; Vanderstraeten, G; Deprez, P

    2003-04-26

    Horses need to be sedated before they are investigated by transcranial magnetic stimulation because of the mild discomfort induced by the evoked muscle contraction and the noise of stimulation. This paper describes the influence of a combination of detomidine (10 microg/kg bodyweight) and a low dose of buprenorphine (2.4 microg/kg) on the onset latency and peak-to-peak amplitude of magnetic motor-evoked potentials in normal horses. There were no significant differences between measurements of these parameters made before the horses were sedated and measurements made 10 and 30 minutes after the drugs were administered.

  16. A comparison of auditory evoked potentials to acoustic beats and to binaural beats

    Pratt, H; Starr, A; Michalewski, HJ; Dimitrijevic, A; Bleich, N; Mittelman, N

    2010-01-01

    The purpose of this study was to compare cortical brain responses evoked by amplitude modulated acoustic beats of 3 and 6 Hz in tones of 250 and 1000 Hz with those evoked by their binaural beats counterparts in unmodulated tones to indicate whether the cortical processes involved differ. Event-related potentials (ERPs) were recorded to 3- and 6-Hz acoustic and binaural beats in 2000 ms duration 250 and 1000 Hz tones presented with approximately 1 s intervals. Latency, amplitude and source cur...

  17. Pressurized-thermal-shock technology

    Dickson, T.L.

    1991-01-01

    It was recognized at the time the original Issues on Pressurized Thermal Shock (IPTS) studies were conducted that distinct vertical plumes of cooling water form beneath the cold leg inlet nozzles during those particular transients that exhibit fluid/thermal stratification. The formation of these plumes (referred to as thermal streaming) induces a time-dependent circumferential temperature variation on the inner surface of the Reactor Pressure Vessel (RPV) wall that creates an axial stress component. This axial stress component is in addition to the axial stress components induced by time-dependent radial temperature variation through the wall thickness and the time-dependent pressure transient. This additional axial stress component will result in a larger axial stress resultant that results in a larger stress-intensity factor acting on circumferential flaws, thus reducing the fracture margin for circumferential flaws. Although this was recognized at the time of the original IPTS study, the contribution appeared to be relatively small; therefore, it was neglected. The original IPTS studies were performed with OCA-P, a computer program developed at ORNL to analyze the cleavage fracture response of a nuclear RPV subjected to PTS loading. OCA-P is a one-dimensional (1-D) finite-element code that analyzes the stresses and stress-intensity factors (axial and tangential) resulting from the pressure and the radial temperature variation through the wall thickness only. The HSST Program is investigating the potential effects of thermal-streaming-induced stresses in circumferential welds on the reactor vessel PTS analyses. The initial phase of this investigation focused on an evaluation of the available thermal-hydraulic data and analyses results. The objective for the initial phase of the investigation is to evaluate thermal-streaming behavior under conditions relevant to the operation of U.S. PWRs and chracterize any predicted thermal-streaming plumes

  18. Effects of response-shock interval and shock intensity on free-operant avoidance responding in the pigeon1

    Klein, Marty; Rilling, Mark

    1972-01-01

    Two experiments investigated free-operant avoidance responding with pigeons using a treadle-pressing response. In Experiment I, pigeons were initially trained on a free-operant avoidance schedule with a response-shock interval of 32 sec and a shock-shock interval of 10 sec, and were subsequently exposed to 10 values of the response-shock parameter ranging from 2.5 to 150 sec. The functions relating response rate to response-shock interval were similar to the ones reported by Sidman in his 1953 studies employing rats, and were independent of the order of presentation of the response-shock values. Shock rates decreased as response-shock duration increased. In Experiment II, a free-operant avoidance schedule with a response-shock interval of 20 sec and a shock-shock interval of 5 sec was used, and shock intensities were varied over five values ranging from 2 to 32 mA. Response rates increased markedly as shock intensity increased from 2 to 8 mA, but rates changed little with further increases in shock intensity. Shock rates decreased as intensity increased from 2 to 8 mA, and showed little change as intensity increased from 8 to 32 mA. PMID:4652617

  19. Role of echocardiography in reducing shock reversal time in pediatric septic shock: a randomized controlled trial

    Ahmed A. EL-Nawawy

    Full Text Available Abstract Objective: To evaluate the role of echocardiography in reducing shock reversal time in pediatric septic shock. Methods: A prospective study conducted in the pediatric intensive care unit of a tertiary care teaching hospital from September 2013 to May 2016. Ninety septic shock patients were randomized in a 1:1 ratio for comparing the serial echocardiography-guided therapy in the study group with the standard therapy in the control group regarding clinical course, timely treatment, and outcomes. Results: Shock reversal was significantly higher in the study group (89% vs. 67%, with significantly reduced shock reversal time (3.3 vs. 4.5 days. Pediatric intensive care unit stay in the study group was significantly shorter (8 ± 3 vs. 14 ± 10 days. Mortality due to unresolved shock was significantly lower in the study group. Fluid overload was significantly lower in the study group (11% vs. 44%. In the study group, inotropes were used more frequently (89% vs. 67% and initiated earlier (12[0.5-24] vs. 24[6-72] h with lower maximum vasopressor inotrope score (120[30-325] vs. 170[80-395], revealing predominant use of milrinone (62% vs. 22%. Conclusion: Serial echocardiography provided crucial data for early recognition of septic myocardial dysfunction and hypovolemia that was not apparent on clinical assessment, allowing a timely management and resulting in shock reversal time reduction among children with septic shock.

  20. Riboflavin protects mice against liposaccharide-induced shock through expression of heat shock protein 25

    Riboflavin (vitamin B2) is a water-soluble vitamin essential for normal cellular functions, growth and development. The study was aimed at investigating the effects of vitamin B2 on the survival rate, and expressions of tissue heat shock protein 25 (HSP25) and heat shock factor 1 (HSF1) in mice und...

  1. PARTICLE ACCELERATION AT THE HELIOSPHERIC TERMINATION SHOCK WITH A STOCHASTIC SHOCK OBLIQUITY APPROACH

    Arthur, Aaron D.; Le Roux, Jakobus A.

    2013-01-01

    Observations by the plasma and magnetic field instruments on board the Voyager 2 spacecraft suggest that the termination shock is weak with a compression ratio of ∼2. However, this is contrary to the observations of accelerated particle spectra at the termination shock, where standard diffusive shock acceleration theory predicts a compression ratio closer to ∼2.9. Using our focused transport model, we investigate pickup proton acceleration at a stationary spherical termination shock with a moderately strong compression ratio of 2.8 to include both the subshock and precursor. We show that for the particle energies observed by the Voyager 2 Low Energy Charged Particle (LECP) instrument, pickup protons will have effective length scales of diffusion that are larger than the combined subshock and precursor termination shock structure observed. As a result, the particles will experience a total effective termination shock compression ratio that is larger than values inferred by the plasma and magnetic field instruments for the subshock and similar to the value predicted by diffusive shock acceleration theory. Furthermore, using a stochastically varying magnetic field angle, we are able to qualitatively reproduce the multiple power-law structure observed for the LECP spectra downstream of the termination shock

  2. A shock surface geometry - The February 15-16, 1967, event. [solar flare associated interplanetary shock

    Lepping, R. P.; Chao, J. K.

    1976-01-01

    An estimated shape is presented for the surface of the flare-associated interplanetary shock of February 15-16, 1967, as seen in the ecliptic-plane cross section. The estimate is based on observations by Explorer 33 and Pioneers 6 and 7. The estimated shock normal at the Explorer 33 position is obtained by a least-squares shock parameter-fitting procedure for that satellite's data; the shock normal at the Pioneer 7 position is found by using the magnetic coplanarity theorem and magnetic-field data. The average shock speed from the sun to each spacecraft is determined along with the local speed at Explorer 33 and the relations between these speeds and the position of the initiating solar flare. The Explorer 33 shock normal is found to be severely inclined and not typical of interplanetary shocks. It is shown that the curvature of the shock surface in the ecliptic plane near the earth-Pioneer 7 region is consistent with a radius of not more than 0.4 AU.

  3. Culture Shock: Information Packet for Developing Stress/Culture Shock Programs for Students in Overseas Schools.

    Robinson, John

    This booklet, written for elementary teachers and counselors, provides information for a three-session stress and culture shock program for fifth and sixth grade students in overseas schools. Session 1 presents an introduction to the program, including discussion questions. Session 2 focuses on stress and culture shock through examples and…

  4. Holographic interferometric observation of shock wave focusing to extracorporeal shock wave lithotripsy

    Takayama, Kazuyoshi; Obara, Tetsuro; Onodera, Osamu

    1991-04-01

    Underwater shock wave focusing is successfully applied to disintegrate and remove kidney stones or gallbladder stones without using surgical operations. This treatment is one of the most peaceful applications ofshock waves and is named as the Extracorporeal Shock Wave Lithotripsy. Ajoint research project is going on between the Institute ofFluid Science, Tohoku University and the School ofMedicine, Tohoku University. The paper describes a result of the fundamental research on the underwater shock wave focusing applied to the ESWL. Quantitatively to visualize the underwater shock waves, various optical flow visualization techniques were successfully used such as holographic interferometry, and shadowgraphs combined with Ima-Con high speed camera. Double exposure holographic interferometric observation revealed the mechanism of generation, propagation and focusing of underwater shock waves. The result of the present research was already used to manufacture a prototype machine and it has already been applied successfully to ESWL crinical treatments. However, despite of success in the clinical treatments, important fundamental questions still remain unsolved, i.e., effects of underwater shock wave focusing on tissue damage during the treatment. Model experiments were conducted to clarify mechanism of the tissue damage associated with the ESWL. Shock-bubble interactions were found responsible to the tissue damage during the ESWL treatment. In order to interprete experimental findings and to predict shock wave behavior and high pressures, a numerical simulation was carried. The numerical results agreed with the experiments.

  5. Diffusive Shock Acceleration and Turbulent Reconnection

    Garrel, Christian; Vlahos, Loukas; Isliker, Heinz; Pisokas, Theophilos

    2018-05-01

    Diffusive Shock Acceleration (DSA) cannot efficiently accelerate particles without the presence of self-consistently generated or pre-existing strong turbulence (δB/B ˜ 1) in the vicinity of the shock. The problem we address in this article is: if large amplitude magnetic disturbances are present upstream and downstream of a shock then Turbulent Reconnection (TR) will set in and will participate not only in the elastic scattering of particles but also in their heating and acceleration. We demonstrate that large amplitude magnetic disturbances and Unstable Current Sheets (UCS), spontaneously formed in the strong turbulence in the vicinity of a shock, can accelerate particles as efficiently as DSA in large scale systems and on long time scales. We start our analysis with "elastic" scatterers upstream and downstream and estimate the energy distribution of particles escaping from the shock, recovering the well known results from the DSA theory. Next we analyze the additional interaction of the particles with active scatterers (magnetic disturbances and UCS) upstream and downstream of the shock. We show that the asymptotic energy distribution of the particles accelerated by DSA/TR has very similar characteristics with the one due to DSA alone, but the synergy of DSA with TR is much more efficient: The acceleration time is an order of magnitude shorter and the maximum energy reached two orders of magnitude higher. We claim that DSA is the dominant acceleration mechanism in a short period before TR is established, and then strong turbulence will dominate the heating and acceleration of the particles. In other words, the shock serves as the mechanism to set up a strongly turbulent environment, in which the acceleration mechanism will ultimately be the synergy of DSA and TR.

  6. On ion injection at quasiparallel shocks

    Scholer, M.; Kucharek, H.; Kato, C.

    2002-01-01

    A large number of numerical experiments has been performed in order to study the interaction of interstellar pickup protons and helium ions with quasiparallel collisionless shocks. The shocks are modeled by a one-dimensional hybrid simulation method which treats the ions as macroparticles and the electrons as a massless fluid. Solar wind alpha particles and pickup protons are included self-consistently. In addition, the particle splitting method is used for the solar wind ions so that the distribution function can be followed over more than 10 orders of magnitude. A large part of the pickup ion distribution is reflected; the reflection efficiency is very high, and can reach in cases where the pickup ion density is low as much as 50%-60%. The reflection efficiency is almost independent of magnetic field-shock normal angle. This indicates that magnetic mirroring is unimportant and does not lead to larger reflection efficiencies. The reflection efficiency of pickup protons rapidly decreases when the pickup ion density exceeds a few percent of the solar wind density. An addition of 25% pickup protons decreases the reflection coefficient for these ions to ∼10%. This represents the fact that a quasiparallel shock cannot be considered as being uncoupled from the upstream region: at high additions of pickup ions the shock structure is changed in such a way as to reflect less pickup ions. The intensity of diffuse ions upstream of a quasiparallel shock does not depend on the temperature of the core distribution. Within the framework of the present model even solar wind distributions with a hard power law tail do not produce higher intensities of diffuse ions. It is argued that this can be understood by the fact that the intrinsic self-consistency between the processes in the upstream region and at the shock transition determines the injection and reflection properties of the core solar wind distribution

  7. Is shock index associated with outcome in children with sepsis/septic shock?*.

    Yasaka, Yuki; Khemani, Robinder G; Markovitz, Barry P

    2013-10-01

    To investigate the association between PICU shock index (the ratio of heart rate to systolic blood pressure) and PICU mortality in children with sepsis/septic shock. To explore cutoff values for shock index for ICU mortality, how change in shock index over the first 6 hours of ICU admission is associated with outcome, and how the use of vasoactive therapy may affect shock index and its association with outcome. Retrospective cohort. Single-center tertiary PICU. Five hundred forty-four children with the diagnosis of sepsis/septic shock. None. From January 2003 to December 2009, 544 children met International Pediatric Sepsis Consensus Conference of 2005 criteria for sepsis/septic shock. Overall mortality was 23.7%. Among all patients, hourly shock index was associated with mortality: odds ratio of ICU mortality at 0 hour, 1.08, 95% CI (1.04-1.12); odds ratio at 1 hour, 1.09 (1.04-1.13); odds ratio at 2 hours, 1.09 (1.05-1.13); and odds ratio at 6 hours, 1.11 (1.06-1.15). When stratified by age, early shock index was associated with mortality only in children 1-3 and more than or equal to 12 years old. Area under the receiver operating characteristic curve in age 1-3 and more than or equal to 12 years old for shock index at admission was 0.69 (95% CI, 0.58-0.80) and 0.62 (95% CI, 0.52-0.72) respectively, indicating a fair predictive marker. Although higher shock index was associated with increased risk of mortality, there was no particular cutoff value with adequate positive or negative likelihood ratios to identify mortality in any age group of children. The improvement of shock index in the first 6 hours of ICU admission was not associated with outcome when analyzed in all patients. However, among patients whose shock index were above the 50th percentile at ICU admission for each age group, improvement of shock index was associated with lower ICU mortality in children between 1-3 and more than or equal to 12 years old (p = 0.02 and p = 0.03, respectively). When

  8. On possible structures of normal ionizing shock waves in electromagnetic shock tubes

    Liberman, M.A.; Synakh, V.S.; Zakajdakhov, V.V.; Velikovich, A.L.

    1982-01-01

    The problem of possible structures of normal ionizing shock waves is studied. On the basis of the general theory of ionizing shock waves in magnetic fields, a similarity solution of the piston problem for an impenetrable piston and a magnetic piston is described and a numerical solution of the non-stationary piston problem is obtained. It is shown that precursor photo-ionization of the neutral gas by the radiation of the shock-heated gas is the dominant factor in shaping normal ionizing shock structures. In particular, it is shown that the strong overheating of atoms and ions in shock fronts is due to the tensor form of Ohm's law in the precursor region. (author)

  9. Multiple spacecraft observations of interplanetary shocks: four spacecraft determination of shock normals

    Russell, C.T.; Mellott, M.M.; Smith, E.J.; King, J.H.

    1983-01-01

    ISEE 1,2,3 IMP8, and Prognoz 7 observations of interplanetary shocks in 1978 and 1979 provide five instances where a single shock is observed by four spacecraft. These observations are used to determine best-fit normals for these five shocks. In addition to providing well-documented shocks for furture techniques. When the angle between upstream and downstream magnetic field is greater than 20, magnetic coplanarity can be an accurate single spacecraft method. However, no technique based solely on the magnetic measurements at one or multiple sites was universally accurate. Thus, we recommend using overdetermined shock normal solutions whenever possible, utilizing plasma measurements, separation vectors, and time delays together with magnetic constraints

  10. The MHD intermediate shock interaction with an intermediate wave: Are intermediate shocks physical?

    Wu, C.C.

    1988-01-01

    Contrary to the usual belief that MHD intermediate shocks are extraneous, the authors have recently shown by numerical solutions of dissipative MHD equations that intermediate shocks are admissible and can be formed through nonlinear steepening from a continuous wave. In this paper, he clarifies the differences between the conventional view and the results by studying the interaction of an MHD intermediate shock with an intermediate wave. The study reaffirms his results. In addition, the study shows that there exists a larger class of shocklike solutions in the time-dependent dissiaptive MHD equations than are given by the MHD Rankine-Hugoniot relations. it also suggests a mechanism for forming rotational discontinuities through the interaction of an intermediate shock with an intermediate wave. The results are of importance not only to the MHD shock theory but also to studies such as magnetic field reconnection models

  11. Application of Underwater Shock Wave Focusing to the Development of Extracorporeal Shock Wave Lithotripsy

    Takayama, Kazuyoshi

    1993-05-01

    This paper describes a summary of a research project for the development of extracorporeal shock wave lithotripsy (ESWL), which has been carried out, under close collaboration between the Shock Wave Research Center of Tohoku University and the School of Medicine, Tohoku University. The ESWL is a noninvasive clinical treatment of disintegrating human calculi and one of the most peaceful applications of shock waves. Underwater spherical shock waves were generated by explosion of microexplosives. Characteristics of the underwater shock waves and of ultrasound focusing were studied by means of holographic interferometric flow visualization and polyvinyliden-difluoride (PVDF) pressure transducers. These focused pressures, when applied to clinical treatments, could effectively and noninvasively disintegrate urinary tract stones or gallbladder stones. However, despite clincal success, tissue damage occurs during ESWL treatments, and the possible mechanism of tissue damage is briefly described.

  12. Effects of Alfvénic Drift on Diffusive Shock Acceleration at Weak Cluster Shocks

    Kang, Hyesung; Ryu, Dongsu

    2018-03-01

    Non-detection of γ-ray emission from galaxy clusters has challenged diffusive shock acceleration (DSA) of cosmic-ray (CR) protons at weak collisionless shocks that are expected to form in the intracluster medium. As an effort to address this problem, we here explore possible roles of Alfvén waves self-excited via resonant streaming instability during the CR acceleration at parallel shocks. The mean drift of Alfvén waves may either increase or decrease the scattering center compression ratio, depending on the postshock cross-helicity, leading to either flatter or steeper CR spectra. We first examine such effects at planar shocks, based on the transport of Alfvén waves in the small amplitude limit. For the shock parameters relevant to cluster shocks, Alfvénic drift flattens the CR spectrum slightly, resulting in a small increase of the CR acceleration efficiency, η. We then consider two additional, physically motivated cases: (1) postshock waves are isotropized via MHD and plasma processes across the shock transition, and (2) postshock waves contain only forward waves propagating along with the flow due to a possible gradient of CR pressure behind the shock. In these cases, Alfvénic drift could reduce η by as much as a factor of five for weak cluster shocks. For the canonical parameters adopted here, we suggest η ∼ 10‑4–10‑2 for shocks with sonic Mach number M s ≈ 2–3. The possible reduction of η may help ease the tension between non-detection of γ-rays from galaxy clusters and DSA predictions.

  13. Shock interactions with heterogeneous energetic materials

    Yarrington, Cole D.; Wixom, Ryan R.; Damm, David L.

    2018-03-01

    The complex physical phenomenon of shock wave interaction with material heterogeneities has significant importance and nevertheless remains little understood. In many materials, the observed macroscale response to shock loading is governed by characteristics of the microstructure. Yet, the majority of computational studies aimed at predicting phenomena affected by these processes, such as the initiation and propagation of detonation waves in explosives or shock propagation in geological materials, employ continuum material and reactive burn model treatment. In an effort to highlight the grain-scale processes that underlie the observable effects in an energetic system, a grain-scale model for hexanitrostilbene (HNS) has been developed. The measured microstructures were used to produce synthetic computational representations of the pore structure, and a density functional theory molecular dynamics derived equation of state (EOS) was used for the fully dense HNS matrix. The explicit inclusion of the microstructure along with a fully dense EOS resulted in close agreement with historical shock compression experiments. More recent experiments on the dynamic reaction threshold were also reproduced by inclusion of a global kinetics model. The complete model was shown to reproduce accurately the expected response of this heterogeneous material to shock loading. Mesoscale simulations were shown to provide a clear insight into the nature of threshold behavior and are a way to understand complex physical phenomena.

  14. Constitutive modeling of shock response of PTFE

    Brown, Eric N [Los Alamos National Laboratory; Reanyansky, Anatoly D [DSTO, AUSTRALIA; Bourne, Neil K [AWE, UK; Millett, Jeremy C F [AWE, UK

    2009-01-01

    The PTFE (polytetrafluoroethylene) material is complex and attracts attention of the shock physics researchers because it has amorphous and crystalline components. In turn, the crystalline component has four known phases with the high pressure transition to phase III. At the same time, as has been recently studied using spectrometry, the crystalline region is growing with load. Stress and velocity shock-wave profiles acquired recently with embedded gauges demonstrate feature that may be related to impedance mismatches between the regions subjected to some transitions resulting in density and modulus variations. We consider the above mentioned amorphous-to-crystalline transition and the high pressure Phase II-to-III transitions as possible candidates for the analysis. The present work utilizes a multi-phase rate sensitive model to describe shock response of the PTFE material. One-dimensional experimental shock wave profiles are compared with calculated profiles with the kinetics describing the transitions. The objective of this study is to understand the role of the various transitions in the shock response of PTFE.

  15. Advances in NIF Shock Timing Experiments

    Robey, Harry

    2012-10-01

    Experiments are underway to tune the shock timing of capsule implosions on the National Ignition Facility (NIF). These experiments use a modified cryogenic hohlraum geometry designed to precisely match the performance of ignition hohlraums. The targets employ a re-entrant Au cone to provide optical access to multiple shocks as they propagate in the liquid deuterium-filled capsule interior. The strength and timing of all four shocks is diagnosed with VISAR (Velocity Interferometer System for Any Reflector). Experiments are now routinely conducted in a mirrored keyhole geometry, which allows for simultaneous diagnosis of the shock timing at both the hohlraum pole and equator. Further modifications are being made to improve the surrogacy to ignition hohlraums by replacing the standard liquid deuterium (D2) capsule fill with a deuterium-tritium (DT) ice layer. These experiments will remove any possible surrogacy difference between D2 and DT as well as incorporate the physics of shock release from the ice layer, which is absent in current experiments. Experimental results and comparisons with numerical simulation are presented.

  16. Energy shocks and detecting influential industries

    Kang, Dongsuk; Lee, Duk Hee

    2017-01-01

    An industry's relationship of supply and demand with the energy sector can be a critical factor in the stability of its economic performance. Furthermore, the patterns of industry dependence on energy industries can be a major characteristic of entire industrial structure. This research evaluates industries' impact scores for their overall influence on other industries and vulnerability to supply and demand shocks from the energy sector. The study utilizes a sample of Korea's industrial input–output tables from 2010 to 2012. Using a chain of complementary methodologies, this study finds that among four clusters, energy, services, and raw materials are key members that can spread energy shocks to other industries. Therefore, governments need to prepare effective energy efficiency policies for these target industries. - Highlights: • We analyze an industry's impact score of its vulnerability to energy shock and inter-industrial effects. • We utilize the sample of input-output tables in Korea from 2010 to 2012. • We implement simulation, PCA, TOPSIS, cluster analysis about energy shock and industrial trades. • Subsectors of energy, services, raw material are subject to energy shock and influential to others. • These bridge industries can be targets that require policies for effective energy efficiency.

  17. Dopamine versus noradrenaline in septic shock

    Bo Xu

    2011-10-01

    Full Text Available BackgroundThe ‘Surviving Sepsis’ Campaign guidelines recommend theuse of dopamine or noradrenaline as the first vasopressor inseptic shock. However, information that guides clinicians inchoosing between dopamine and noradrenaline as the firstvasopressor in patients with septic shock is limited.ObjectiveThis article presents a review of the literature regarding theuse of dopamine versus noradrenaline in patients with septicshock.ResultsTwo randomised controlled trials (RCT and two largeprospective cohort studies were analysed. RCT data showeddopamine was associated with increased arrhythmic events.One cohort study found dopamine was associated with higher30-day mortality. The other cohort study found noradrenalinewas associated with higher 28-day mortality.DiscussionData on the use of dopamine versus noradrenaline in patientswith septic shock is limited. Following the recent SOAP IIstudy, there is now strong evidence that the use of dopaminein septic shock is associated with significantly morecardiovascular adverse events, compared tonoradrenaline.ConclusionNoradrenaline should be used as the initial vasopressor inseptic shock to avoid the arrhythmic events associatedwith dopamine.

  18. Thermal shock cracking of GSO single crystal

    Miyazaki, Noriyuki; Yamamoto, Kazunari; Tamura, Takaharu; Kurashige, Kazuhisa; Ishibashi, Hiroyuki; Susa, Kenzo

    1998-01-01

    The quantitative estimation of the failure stress of a gadolinium orthosilicate (Gd 2 SiO 5 , hereafter abbreviated as GSO) single crystal due to thermal shock was investigated. A cylindrical test specimen was heated in a silicone oil bath, then subjected to thermal shock by pouring room temperature silicone oil. Cracking occurred during cooling. The heat conduction analysis was performed to obtain temperature distribution in a GSO single crystal at cracking, using the surface temperatures measured in the thermal shock cracking test. Then the thermal stress was calculated using temperature profile of the test specimen obtained from the heat conduction analysis. It is found from the results of the thermal stress analysis and the observation of the cracking in test specimens that the thermal shock cracking occurs in a cleavage plane due to the stress normal to the plane. Three-point bending tests were also performed to examine the relationship between the critical stress for thermal shock cracking and the three-point bending strength obtained from small-sized test specimens. (author)

  19. Analytical model for fast-shock ignition

    Ghasemi, S. A.; Farahbod, A. H.; Sobhanian, S.

    2014-01-01

    A model and its improvements are introduced for a recently proposed approach to inertial confinement fusion, called fast-shock ignition (FSI). The analysis is based upon the gain models of fast ignition, shock ignition and considerations for the fast electrons penetration into the pre-compressed fuel to examine the formation of an effective central hot spot. Calculations of fast electrons penetration into the dense fuel show that if the initial electron kinetic energy is of the order ∼4.5 MeV, the electrons effectively reach the central part of the fuel. To evaluate more realistically the performance of FSI approach, we have used a quasi-two temperature electron energy distribution function of Strozzi (2012) and fast ignitor energy formula of Bellei (2013) that are consistent with 3D PIC simulations for different values of fast ignitor laser wavelength and coupling efficiency. The general advantages of fast-shock ignition in comparison with the shock ignition can be estimated to be better than 1.3 and it is seen that the best results can be obtained for the fuel mass around 1.5 mg, fast ignitor laser wavelength ∼0.3  micron and the shock ignitor energy weight factor about 0.25

  20. Shock analysis: Three useful new relations

    Smith, E.J.; Burton, M.E.

    1988-01-01

    Over the years a variety of methods for analyzing hydromagnetic shocks have been developed. The Rankine-Hugoniot relations on which the analyses are based are sufficiently complex and involve sufficiently large numbers of variables that in specific instances a decision must be made on how to proceed. The authors analyses have tended to emphasize the magnetic field (B) and velocity (V) as the starting point since they are typically the most accurately determined measurables. They authors have also tended to carry out the analysis in a reference frame aligned, and moving, with the shock. Three new relations have been derived which are generally useful. (1) The shock speed can be calculated from the upstream and downstream values of B and V independent of the shock normal or its direction relative to the upstream field. (2) An explicit relation is derived relating the angles between the jump in velocity, the shock normal, and the upstream field. (3) From the magnetic field and two-dimensional velocity measurements, which are frequently all that are available, it is possible to infer the third component of the upstream-downstream velocity jump

  1. A comparison of myogenic motor evoked responses to electrical and magnetic transcranial stimulation during nitrous oxide/opioid anesthesia

    Ubags, L. H.; Kalkman, C. J.; Been, H. D.; Koelman, J. H.; Ongerboer de Visser, B. W.

    1999-01-01

    Transcranial motor evoked potentials (tc-MEPs) are used to monitor spinal cord integrity intraoperatively. We compared myogenic motor evoked responses with electrical and magnetic transcranial stimuli during nitrous oxide/opioid anesthesia. In 11 patients undergoing spinal surgery, anesthesia was

  2. Intrasexual competition at work : Sex differences in the jealousy-evoking effect of rival characteristics in work settings

    Buunk, Abraham P.; 't Goor, Joel Aan; Solano, Alejandro C.

    Sex differences in jealousy-evoking rival characteristics in the relationship with a supervisor at work were examined in a community sample of 188 individuals from Argentina. Among men, the rivals' social dominance and communal attributes evoked the most jealousy, followed by physical dominance.

  3. INFLUENCE OF DANCE TRAINING ON SACCULOCOLLIC PATHWAY: VESTIBULAR EVOKED MYOGENIC POTENTIALS (VEMP) AS AN OBJECTIVE TOOL

    Swathi; Sathish Kumar

    2013-01-01

    ABSTRACT : Auditory system is shaped by experience and training. Training (s ensory experience) induces neurophysiologic changes & plasticity in normal hearing individuals, hearing loss patients, hearing aid users and cochlear implanted subjects. Not only speech stimulus, but music also brings about functional and structural organi zation of the brain in musician compared to non - musicians. The Vestibular evoked myogenic potentials (VEMP) are a biphasic in...

  4. Predictability of painful stimulation modulates the somatosensory-evoked potential in the rat

    Schaap, M.W.H.; van Oostrom, H.; Doornenbal, A.; Baars, A.M.; Arndt, S.S.; Hellebrekers, L.J.

    2013-01-01

    Abstract Somatosensory-evoked potentials (SEPs) are used in humans and animals to increase knowledge about nociception and pain. Since the SEP in humans increases when noxious stimuli are administered unpredictably, predictability potentially influences the SEP in animals as well. To assess the

  5. Steady-state evoked potentials possibilities for mental-state estimation

    Junker, Andrew M.; Schnurer, John H.; Ingle, David F.; Downey, Craig W.

    1988-01-01

    The use of the human steady-state evoked potential (SSEP) as a possible measure of mental-state estimation is explored. A method for evoking a visual response to a sum-of-ten sine waves is presented. This approach provides simultaneous multiple frequency measurements of the human EEG to the evoking stimulus in terms of describing functions (gain and phase) and remnant spectra. Ways in which these quantities vary with the addition of performance tasks (manual tracking, grammatical reasoning, and decision making) are presented. Models of the describing function measures can be formulated using systems engineering technology. Relationships between model parameters and performance scores during manual tracking are discussed. Problems of unresponsiveness and lack of repeatability of subject responses are addressed in terms of a need for loop closure of the SSEP. A technique to achieve loop closure using a lock-in amplifier approach is presented. Results of a study designed to test the effectiveness of using feedback to consciously connect humans to their evoked response are presented. Findings indicate that conscious control of EEG is possible. Implications of these results in terms of secondary tasks for mental-state estimation and brain actuated control are addressed.

  6. Effect of extradural morphine on somatosensory evoked potentials to dermatomal stimulation

    Lund, C; Selmar, P; Hansen, O B

    1987-01-01

    The effect of the extradural (L2-3) administration of morphine 6 mg on early (less than 0.5 s) somatosensory evoked cortical potentials (SEP) to electrical stimulation of the L1- and S1-dermatomes was examined in eight patients. Extradural morphine did not influence SEP amplitude. SEP latency did...

  7. Effect of caffeine on vestibular evoked myogenic potential: a systematic review with meta-analysis.

    Souza, Maria Eduarda Di Cavalcanti Alves de; Costa, Klinger Vagner Teixeira da; Menezes, Pedro de Lemos

    2017-12-24

    Caffeine can be considered the most consumed drug by adults worldwide, and can be found in several foods, such as chocolate, coffee, tea, soda and others. Overall, caffeine in moderate doses, results in increased physical and intellectual productivity, increases the capacity of concentration and reduces the time of reaction to sensory stimuli. On the other hand, high doses can cause noticeable signs of mental confusion and error induction in intellectual tasks, anxiety, restlessness, muscle tremors, tachycardia, labyrinthine changes, and tinnitus. Considering that the vestibular evoked myogenic potential is a clinical test that evaluates the muscular response of high intensity auditory stimulation, the present systematic review aimed to analyze the effects of caffeine on vestibular evoked myogenic potential. This study consisted of the search of the following databases: MEDLINE, CENTRAL, ScienceDirect, Scopus, Web of Science, LILACS, SciELO and ClinicalTrials.gov. Additionally, the gray literature was also searched. The search strategy included terms related to intervention (caffeine or coffee consumption) and the primary outcome (vestibular evoked myogenic potential). Based on the 253 potentially relevant articles identified through the database search, only two full-text publications were retrieved for further evaluation, which were maintained for qualitative analysis. Analyzing the articles found, caffeine has no effect on vestibular evoked myogenic potential in normal individuals. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  8. The involuntary nature of music-evoked autobiographical memories in Alzheimer's disease

    El Haj, M.; Fasotti, L.; Allain, P.

    2012-01-01

    The main objective of this paper was to examine the involuntary nature of music-evoked autobiographical memories. For this purpose, young adults, older adults, and patients with a clinical diagnosis of probable Alzheimer’s disease (AD) were asked to remember autobiographical events in two

  9. Multi-channel motor evoked potential monitoring during anterior cervical discectomy and fusion

    Dong-Gun Kim

    Full Text Available Objectives: Anterior cervical discectomy and fusion (ACDF surgery is the most common surgical procedure for the cervical spine with low complication rate. Despite the potential prognostic benefit, intraoperative neurophysiological monitoring (IONM, a method for detecting impending neurological compromise, is not routinely used in ACDF surgery. The present study aimed to identify the potential benefits of monitoring multi-channel motor evoked potentials (MEPs during ACDF surgery. Methods: We retrospectively reviewed 200 consecutive patients who received IONM with multi-channel MEPs and somatosensory evoked potentials (SSEPs. On average, 9.2 muscles per patient were evaluated under MEP monitoring. Results: The rate of MEP change during surgery in the multi-level ACDF group was significantly higher than the single-level group. Two patients from the single-level ACDF group (1.7% and four patients from the multi-level ACDF group (4.9% experienced post-operative motor deficits. Multi-channel MEPs monitoring during single and multi-level ACDF surgery demonstrated higher sensitivity, specificity, positive predictive and negative predictive value than SSEP monitoring. Conclusions: Multi-channel MEP monitoring might be beneficial for the detection of segmental injury as well as long tract injury during single- and multi-level ACDF surgery. Significance: This is first large scale study to identify the usefulness of multi-channel MEPs in monitoring ACDF surgery. Keywords: Disc disease, Somatosensory evoked potentials, Intraoperative neurophysiological monitoring, Motor evoked potentials, Anterior cervical discectomy and fusion

  10. Exploring the methods of data analysis in multifocal visual evoked potentials

    Malmqvist, Lasse; Santiago de Abreu, Lucimar; Fraser, C.

    2016-01-01

    Purpose: The multifocal visual evoked potential (mfVEP) provides a topographical assessment of visual function, which has already shown potential for use in patients with glaucoma and multiple sclerosis. However, the variability in mfVEP measurements has limited its broader application. The purpo...

  11. Click-evoked otoacoustic emissions in children and adolescents with gender identity disorder

    Burke, Sarah M; Menks, Willeke M; Cohen-Kettenis, Peggy T; Klink, Daniel T; Bakker, J.

    2014-01-01

    Click-evoked otoacoustic emissions (CEOAEs) are echo-like sounds that are produced by the inner ear in response to click-stimuli. CEOAEs generally have a higher amplitude in women compared to men and neonates already show a similar sex difference in CEOAEs. Weaker responses in males are proposed to

  12. Click-Evoked Otoacoustic Emissions in Children and Adolescents with Gender Identity Disorder

    Burke, S.M.; Menks, W.M.; Cohen-Kettenis, P.T.; Klink, D.T.; Bakker, J.

    2014-01-01

    Click-evoked otoacoustic emissions (CEOAEs) are echo-like sounds that are produced by the inner ear in response to click-stimuli. CEOAEs generally have a higher amplitude in women compared to men and neonates already show a similar sex difference in CEOAEs. Weaker responses in males are proposed to

  13. Transmitter modulation of spike-evoked calcium transients in arousal related neurons

    Kohlmeier, Kristi Anne; Leonard, Christopher S

    2006-01-01

    Nitric oxide synthase (NOS)-containing cholinergic neurons in the laterodorsal tegmentum (LDT) influence behavioral and motivational states through their projections to the thalamus, ventral tegmental area and a brainstem 'rapid eye movement (REM)-induction' site. Action potential-evoked intracel......Nitric oxide synthase (NOS)-containing cholinergic neurons in the laterodorsal tegmentum (LDT) influence behavioral and motivational states through their projections to the thalamus, ventral tegmental area and a brainstem 'rapid eye movement (REM)-induction' site. Action potential......-evoked intracellular calcium transients dampen excitability and stimulate NO production in these neurons. In this study, we investigated the action of several arousal-related neurotransmitters and the role of specific calcium channels in these LDT Ca(2+)-transients by simultaneous whole-cell recording and calcium...... of cholinergic LDT neurons and that inhibition of spike-evoked Ca(2+)-transients is a common action of neurotransmitters that also activate GIRK channels in these neurons. Because spike-evoked calcium influx dampens excitability, our findings suggest that these 'inhibitory' transmitters could boost firing rate...

  14. Circulatory response evoked by a 3 s bout of dynamic leg exercise in humans

    Wieling, W.; Harms, M. P.; ten Harkel, A. D.; van Lieshout, J. J.; Sprangers, R. L.

    1996-01-01

    1. The mechanisms underlying the pronounced transient fall in arterial blood pressure evoked by a 3 s bout of bicycle exercise were investigated in twenty healthy young adults and four patients with hypoadrenergic orthostatic hypotension. 2. In healthy subjects a 3 s bout of upright cycling induced

  15. Evidence that 5-hydroxytryptamine/sub 3/ receptors mediate cytotoxic drug and radiation-evoked emesis

    Miner, W.D.; Sanger, G.J.; Turner, D.H.

    1987-08-01

    The involvement of 5-hydroxytryptamine (5-HT) 5-HT/sub 3/ receptors in the mechanisms of severe emesis evoked by cytotoxic drugs or by total body irradiation have been studied in ferrets. Anti-emetic compounds tested were domperidone (a dopamine antagonist), metoclopramide (a gastric motility stimulant and dopamine antagonist at conventional doses, a 5-HT/sub 3/ receptor antagonist at higher doses) and BRL 24924 (a potent gastric motility stimulant and a 5-HT/sub 3/ receptor antagonist). Domperidone or metoclopramide prevented apomorphine-evoked emesis, whereas BRL 24924 did not. Similar doses of domperidone did not prevent emesis evoked by cis-platin or by total body irradiation, whereas metoclopramide or BRL 24924 greatly reduced or prevented these types of emesis. Metoclopramide and BRL 24924 also prevented emesis evoked by a combination of doxorubicin and cyclophosphamide. These results are discussed in terms of a fundamental role for 5-HT/sub 3/ receptors in the mechanisms mediating severely emetogenic cancer treatment therapies.

  16. Effect of surgery on sensory threshold and somatosensory evoked potentials after skin stimulation

    Lund, C; Hansen, O B; Kehlet, H

    1990-01-01

    We have studied the effect of surgical injury on cutaneous sensitivity and somatosensory evoked potentials (SSEP) to dermatomal electrical stimulation in 10 patients undergoing hysterectomy. Forty-eight hours after surgery, sensory threshold increased from 2.2 (SEM 0.3) mA to 4.4 (1.1) mA (P less...

  17. "Passie, Hartstocht": Painting and Evoking Emotions in Rembrandt’s Studio

    Weststeijn, T.; Fritsche, C.; Leonhard, K.; Weber, G.J.M.

    2013-01-01

    Focusing on Rembrandt’s studio, this chapter explores the theory and practice in the depiction of the passions. It argues that the central importance alotted to portraying and evoking emotions in rhetorical theory inspired painterly experiments in the 1630s and theoretical ideals that were first

  18. What reported food-evoked emotions may add : A model to predict consumer food choice

    Gutjar, Swetlana; Dalenberg, Jelle R.; de Graaf, Cees; de Wijk, Rene A.; Palascha, Aikaterini; Renken, Remco J.; Jager, Gerry

    2015-01-01

    Food-evoked emotions provide information that goes beyond the information from traditional hedonic ratings. The objectives of our study were: (i) to investigate how intrinsic (sensory) and extrinsic (packaging) cues affect consumers' emotional responses to foods, and (ii) to explore whether

  19. What reported food-evoked emotions may add: A model to predict consumer food choice

    Gutjar, S.; Dalenberg, J.R.; Graaf, de C.; Wijk, de R.A.; Palascha, A.; Renken, Remco J.; Jager, G.

    2015-01-01

    Food-evoked emotions provide information that goes beyond the information from traditional hedonic ratings. The objectives of our study were: (i) to investigate how intrinsic (sensory) and extrinsic (packaging) cues affect consumers’ emotional responses to foods, and (ii) to explore whether

  20. Proprioceptive evoked potentials in man: cerebral responses to changing weight loads on the hand

    Arnfred, S; He, Chen; Eder, D

    2000-01-01

    We studied cerebral evoked potentials on the scalp to the stimulation of the right hand from a change in weight of 400-480 g in ten subjects. Rise-time was 20g/10 ms, Inter Stimulus Interval 2s and stimulus duration was 100 ms. The cerebral activations were a double positive contralateral C3'/P70...